Studies have demonstrated that perceived health-related quality of life (HRQOL) of patients receiving hemodialysis is significantly impaired. Since HRQOL outcome data are often used to compare groups to determine health care effectiveness it is imperative that measures of HRQOL are valid. However, valid HRQOL comparisons between groups can only be made if instrument invariance is demonstrated. The Kidney Disease Quality of Life-Short Form (KDQOL-SF) is a widely used HRQOL measure for patients with chronic kidney disease (CKD) however, it has not been validated in the Veteran population. Therefore, the purpose of this study was to examine the measurement invariance of the KDQOL-SF across Veterans and non-Veterans with CKD.Data for this study were from two large prospective observational studies of patients receiving hemodialysis: 1) Veteran End-Stage Renal Disease Study (VETERAN) (N = 314) and 2) Dialysis Outcomes and Practice Patterns Study (DOPPS) . Health-related quality of life was measured with the KDQOL-SF, which consists of the SF-36 and the Kidney Disease Component Summary (KDCS). Single-group confirmatory factor analysis was used to evaluate the goodness-of-fit of the hypothesized measurement model for responses to the subscales of the KDCS and SF-36 instruments when analyzed together; and given acceptable goodness-of-fit in each group, multigroup CFA was used to compare the structure of this factor model in the two samples. Pattern of factor loadings , the magnitude of factor loadings (metric invariance), and the magnitude of item intercepts  were assessed as well as the degree to which factors have the same variances, covariances, and means across groups .CFA demonstrated that the hypothesized two-factor model (KDCS and SF-36) fit the data of both the Veteran and DOPPS samples well, supporting configural invariance. Multigroup CFA results concerning metric and scalar invariance suggested partial strict invariance for the SF-36, but only weak invariance for the KDCS. Structural invariance was not supported.Results suggest that Veterans may interpret the KDQOL-SF differently than non-Veterans. Further evaluation of measurement invariance of the KDQOL-SF between Veterans and non-Veterans is needed using large, randomly selected samples before comparisons between these two groups using the KDQOL-SF can be done reliably. The prevalence of chronic kidney disease (CKD) continues to grow each year with the incidence of patients receiving hemodialysis in the United States reaching 310 per million in 2004 . FurtherSince HRQOL outcome data are often used to compare groups to determine health care effectiveness, including medication and treatment procedural effects as well as resource allocation and policy development, it is imperative that HRQOL instruments measure the same latent traits across groups. However, valid HRQOL comparisons between groups can be made only if instrument invariance is demonstrated . In otheRecently, group differences in how to interpret HRQOL measures have been discussed as an issue potentially affecting the validity of comparisons between genders and different cultural groups -17. For Reflections on the Culture of Veterans [Previous studies have demonstrated that Veterans report lower HRQOL than non-Veterans with similar ages and diagnoses ,19. KaziVeterans :"More than enough evidence, from Veterans of every war, has established that combat is only the beginning of the journey. Soldiers come home, just days out of combat, and enter the purgatory that is being a Veteran. No longer true civilians, ex-soldiers enter the culture of veterans. Millions of members strong, Veterans have their own language, symbols, and gathering places where they talk about what Veterans talk about. Civilians are welcome, but it becomes apparent that they do not fit - they ask the wrong questions and say things that veterans leave unsaid. This is the way of cultures and those who belong to them." (p. 337).The culture of Veterans may influence how Veterans interpret HRQOL measures similar to the differences in interpretation of HRQOL items found among other cultures and ethnic groups . IdentifThe issue of measurement invariance concerns the degree to which the items that comprise a measurement instrument have the same meaning and measure the same constructs in the same ways across different groups of respondents. Although scores on measurement instruments are often used to compare levels of responses across different groups, such analyses of mean differences assume that the scores being contrasted are in fact comparable across groups. In this regard, several types of measurement invariance (or construct comparability) are relevant and are most often evaluated using confirmatory factor analysis (CFA) in a sequence of progressively more restrictive hypotheses about equality across groups concerning the pattern of factor loadings , the magnitude of factor loadings (metric invariance), and the magnitude of item intercepts . In assessing factorial differences across groups, it is also important to address issues of structural invariance, or the degree to which factors have the same variances, covariances, and means across groups . AlthougVarying degrees of measurement and structural invariance are possible across groups with respect to any or all of the invariance hypotheses, ranging from the complete absence of invariance to total invariance. Partial invariance exists when some but not all of the parameters being compared are equivalent across groups . Either An initial omnibus test of measurement invariance often entails a comparison of the covariance matrix of item variances and covariances between groups. However, numerous statistical analysts ,26 have configural invariance-that is, whether the same factors and patterns of loadings are appropriate for both groups [p values associated with inferential null-hypothesis testing, the test of configural invariance is merely descriptive.For this reason, focused tests of invariance typically begin by assessing the issue of equal factorial form or h groups ,27. Confh groups . Thus, wmetric invariance [Given configural invariance, more rigorous tests are conducted concerning first the hypothesis of equal factor loadings across groups, or variance ,27,29. Avariance ,31. Numevariance ,32,33 hascalar invariance, or the degree to which the items have the same predicted values across groups when the underlying factor mean is zero [Given some degree of metric invariance, a third form of measurement equivalence concerns  is zero ,27,29. D is zero ,31,34,35 is zero . Strong An additional test of structural invariance concerns the degree to which the underlying factors have the same amount of variance and covary to the same extent across groups. Although this form of invariance is unnecessary for interpretable between-group comparisons of factor means , the equA second test of structural invariance concerns the degree to which the underlying factors produce the same amount of unexplained variance in the items across groups. Although this form of invariance is not a technical requirement for valid between-group comparisons of factor means ,34, the t tests or ANOVAs, are that CFA allows researchers to: (a) operationalize constructs in ways that are appropriately invariant or noninvariant across groups; (b) correct mean levels of constructs for attenuation due to item unreliability; and (c) adjust between-group mean differences for differential item reliability across groups.A final test of structural invariance concerns whether the multiple groups have equivalent means on each underlying factor in the measurement model. The primary advantages of using CFA to compare latent variable means across groups, as opposed to comparing group means on composite indices of unit-weighted summary scores via Data for this study were from two large prospective observational studies of patients in the United States (U.S.) receiving hemodialysis: 1) Veteran End-Stage Renal Disease Study (VETERAN) sample  and 2) DThe VETERAN sample consisted of baseline data of 314 males between the ages of 28-85 years from a large prospective observational study of Veterans dialyzing at Department of Veterans Affairs (VA) facilities or in the private sector during 2001-2003 . VeteranParticipants were recruited from eight VA Medical Centers with outpatient dialysis facilities from 2001 to 2003 and followed for at least six months. Health-related quality of life questionnaires were completed via a phone interview. Institutional review board (IRB) approval was obtained from all VA sites. Coordinators at each site explained the study and obtained written informed consent from patients who were interested in participating.The non-Veteran data are from the first phase of the Dialysis Outcomes and Practice Patterns Study (DOPPS) ,38. The Table Demographic information such as patient age, gender, marital status, race, work status, and educational level were collected using an investigator developed questionnaire.Health-related quality of life was measured with the Kidney Disease Quality of Life Instrument -Short Form (KDQOL-SF). The KDQOL was developed as a self-report, health-related quality of life measurement tool designed specifically for patients with CKD . The 134Missing values occurred between 1% and 10% for all items except for sexual function which was missing greater than 50% of data. The Veteran data set contained less missing data than the DOPPS data set (between 0 to 5% for the Veterans versus 6% to 10% missing data for the DOPPS data set). This difference may have been attributed to the Veteran data being collected over the telephone whereas DOPPS data were collected via written questionnaire. Because of the large amounts of missing data from both the VETERANS and DOPPs samples for the sexual function subscale, sexual function was not included in the calculation of the KDCS. For all other items, missing data were replaced for the KDQOL-SF variables using the SAS 9.2  multiple imputation procedure . The mulN = 314) and DOPPS  samples. As a first step, we evaluated separately for each group the goodness-of-fit of a CFA model that specified two correlated factors consisting of the seven subscales of the KDCS and the eight subscales of the SF-36. The rationale for examining a two-factor, second-order structure considering generic HRQOL as one factor and disease-specific HRQOL as another factor is supported by the literature in which generic HRQOL and disease-specific HRQOL are considered to be distinct, yet complementary concepts [CFA. We used single-group confirmatory factor analysis (CFA) via LISREL 8  to evaluconcepts . In a seconcepts  describeconcepts . Other sconcepts -58.CFA models were analyzed via maximum-likelihood estimation using the covariance matrix of the KDCS and SF-36 subscales. Because HRQOL responses tend to be distributed nonnormally and because nonnormality inflates the goodness-of-fit chi-square, reduces standard errors, and exaggerates statistical significance, we also analyzed the KDCS and SF-36 data using robust maximum likelihood estimation, by analyzing the asymptotic covariance matrices to estimate the Satorra-Bentler scaled chi-square value . An idenTo define the units of variance for each factor in single-group CFA, we standardized the KDCS and SF-36 factors by fixing their variances at 1.0. To define the units of variance for the factors in the multigroup CFA models, we identified a single subscale for each factor that had a virtually identical loading for both groups and then fixed this loading to a value of 1.0 for each group ,60. For We used four different statistical criteria to judge the goodness-of-fit of the hypothesized two-factor CFA model. As measures of absolute fit, we examined the root mean square error of approximation (RMSEA) and the standardized root mean residual (SRMR). RMSEA reflects the size of the residuals that result when using the model to predict the data, adjusting for model complexity, with smaller values indicating better fit. According to Browne and Cudeck , RMSEA <We followed Vandenberg and Lance's  recommenw2, or the ratio of chi-square divided by N [R-squared  in multiple regression. Cohen [w2 ≤ 0.01 is small, w2 = 0.09 is medium, and w2 ≥ 0.25 is large.We used the difference in chi-square values and degrees of freedom, i.e., the likelihood ratio test , to testded by N , which in. Cohen  suggesteIn testing invariance hypotheses, there is disagreement in the literature about whether researchers should test invariance hypotheses globally across all relevant parameters simultaneously  versus test invariance hypotheses separately across relevant sets of parameters . Although omnibus tests of parameter equivalence reduce Type I errors by decreasing the number of statistical tests when the null hypothesis is true, Bontempo and Hofer  have sugp value for each statistical test [p < .05, correcting for the number of statistical comparisons made.To further reduce the likelihood of capitalizing on chance, we corrected the Type I error rate for probability-based tests of invariance (see Cribbie) , by impocal test . Specifical test ,72 to enp-value associated with the likelihood-ratio test; (b) the sequentially-rejective Bonferroni adjusted p-value associated with the likelihood-ratio test; (c) the difference in CFI values (ΔCFI); and (d) effect size (w2). Research comparing the likelihood-ratio test and ΔCFI as criteria for judging measurement invariance [p-values would more often support the rejection of invariance hypotheses relative to the other statistical criteria, given the large sample size for our multigroup analyses . Because the large number of anticipated invariance tests  will produce a more stringent adjusted p-value, we expected that using Bonferroni-adjusted p values would reduce the bias toward rejecting invariance hypotheses via the likelihood-ratio test.In drawing inferences from tests of measurement or structural invariance, we examined four different statistical criteria: (a) the unadjusted variance  suggestsvariance ,73,74, wχ2 = 331.632, RMSEA = .091, SRMR = .058, NNFI = .952, CFI = .959, and χ2 = 2464.593, RMSEA = .086, SRMR = .051, NNFI = .956, CFI = .963, respectively. Table R2 = .394, SF-36 median R2 = .484; DOPPS sample, KDCS median R2 = .398, SF-36 median R2 = .459.CFAs revealed that the hypothesized two-factor model fit the data of both the VETERAN and DOPPS samples reasonably well, 2 = 85% shared variance) and DOPPS (0.8792 = 77% shared variance) samples, they also indicate that roughly one-seventh of the variance in each instrument for the VETERAN sample, and one-quarter of the variance in each instrument for the DOPPS sample, has nothing to do with the other instrument. Furthermore, a one-factor model, representing overall HRQOL, fit the combined KDCS and SF-36 data significantly worse than did the two-factor model for both the VETERAN, Δχ2 = 20.287, p < .0001, and DOPPS samples, Δχ2 = 524.571, p < .0001; and a one-factor model did not yield an acceptable model fit with respect to RMSEA for either the VETERAN, χ2 = 352.459, RMSEA = .102, SRMR = .0589, NNFI = .946, CFI = .954, or DOPPS sample, χ2 = 2989.164, RMSEA = .107, SRMR = .0564, NNFI = .942, CFI = .951.In the completely standardized CFA solution, the KDCS and SF-36 factors correlated 0.924 in the VETERAN sample and 0.879 in the DOPPS sample. Although these factor intercorrelations reflect a high degree of overlap between the two HRQOL instruments in both the VETERAN , we next used multigroup CFA to assess a set of increasingly restrictive hypotheses concerning measurement invariance across the two samples. Analyzing the data for the VETERAN and DOPPS samples in a multigroup model with no cross-group invariance constraints provided the baseline model for subsequent tests of invariance,  and Bonferroni-adjusted (p = ns) criteria. In addition, the effect size of group differences in loadings on the SF-36 factor was modest (w2 = .05), and the change in CFI (ΔCFI = .0002) also suggested invariant SF-36 factor loadings. In contrast, the likelihood-ratio test revealed significant group differences in loadings for the KDCS factor (Model 2) according to both unadjusted (p < .00085) and Bonferroni-adjusted (p < .025) criteria. However, this effect approached only medium size (w2 = .08), and the change in CFI (ΔCFI = .0003) suggested that the VETERAN and DOPPS samples had equivalent loadings on the KDCS factor.In the next step, we examined the magnitude of factor loadings or metric invariance. As seen in Table p < .0069), but for only the Sleep subscale using the adjusted criterion , and all ΔCFIs were within the recommended 0.01 threshold for inferring invariance (ΔCFIs ≤ .0005).Tests of the invariance of factor loadings for each of the non-referent KDCS subscales revealed statistically significant differences in loadings for two subscales  using the unadjusted criterion , we thus sought to establish a partially metric invariant measurement model that constrained the factor loadings for all seven non-referent SFQ subscales and four of the six non-referent KDCS subscales  to be invariant across the VETERAN and DOPPS samples. This partially metric invariant model fit the data well and provided an equivalent goodness-of-fit compared to the initial unconstrained baseline model, Δ = 14.342, unadjusted p < .22, Bonferroni-adjusted p = ns, ΔCFI = .0003, w2 = .06 , an omnibus test of scalar invariance suggested that the five metric-invariant KDCS subscales  had different intercepts for the VETERAN and DOPPS samples (see Table w2 = .15), the difference in CFI again did not reach the 0.01 threshold (ΔCFI = .0019). As seen in Table p < .14, Bonferroni-adjusted p = ns), ΔCFI <0.01, and a small effect size (w2 = .03).As discussed, scalar invariance is the magnitude of item intercepts. According to the likelihood-ratio test . Although the size of this overall effect was relatively large (w2 = .21), the difference in CFI again did not reach the 0.01 threshold (ΔCFI = .004). As seen in Table w2s ≤ .05).Likewise, an omnibus test of scalar invariance suggested that the eight metric-invariant SF-36 subscales  had different intercepts for the VETERAN and DOPPS samples, according to the likelihood-ratio test , half of the eight SF-36 subscales, but only one of the seven KDCS subscales, showed evidence of scalar invariance for the VETERAN and DOPPS groups. These results suggest that strong invariance  exists in partial (50%) form for the SF-36, but only minimal form  for the KDCS. Inspection of CFA solutions revealed that subscales with nonequivalent intercepts had higher values for the VETERAN sample relative to the DOPPS sample.As seen in Table The finding of equal factor variances across groups is important for at least two reasons. First, the invariance of factor variances is a precondition for using the comparison of item unique variances as a test of equal subscale reliabilities across groups ,75. Secow2 = .12) was rejected according to the likelihood-ratio test , but not according to the difference in CFI values (ΔCFI = .0007). Individual follow-up tests (w2s ≤ .05) revealed that five of the KDCS subscales-Social Interaction, Cognitive Functioning, Symptoms, Effects, and Social Support-had invariant unique error variances according to the Bonferroni-adjusted likelihood-ratio test  and the difference in CFI . These results suggest that five (71%) of the seven KDCS subscales were equally reliable for the VETERAN and DOPPS samples. Both of the KDCS subscales (Burden and Sleep) that showed evidence of differential reliability had greater unique error variance for the VETERAN sample than for the DOPPS sample in the partially invariant CFA model.As seen in Table w2 = .09) was rejected according to the unadjusted likelihood-ratio test (p < .0025), but not according to the Bonferroni-adjusted likelihood-ratio test (p = ns) or the difference in CFI . Individual follow-up tests (w2s ≤ .05) revealed that five of the SF-36 subscales-PF, RP, BP, GH, and MH-had invariant unique error variances according to the likelihood-ratio test  and the difference in CFI . In addition, the RE subscale (w2 = .09) and SF subscale (w2 = .04) of the SF-36 had invariant unique error variances according to the Bonferroni-adjusted likelihood ratio test (ps = ns), but not according the unadjusted likelihood-ratio test (ps < .035) or the difference in CFI (ΔCFIs < .0012). And the VT subscale of the SF-36 had a different unique error variance for the two groups according to the likelihood-ratio test , but had a small ΔCFI (.0002) and a small effect size (w2 = .05). These results suggest that at least seven (88%) of the eight SF-36 subscales were equally reliable for the VETERAN and DOPPS samples. The one SF-36 subscale that showed evidence of differential reliability (VT) had greater unique error variance for the VETERAN sample than for the DOPPS sample.Also seen in Table As a final step in our invariance analyses, we tested for group differences in latent means for the KDCS and SF-36 factors, using a multigroup CFA model that specified partially invariant factor loadings , fully invariant factor variances and covariances, and partially invariant unique error variances . Because of problems of under-identification, item intercepts and factor means cannot both be estimated in the same model  nor can Z = 5.253, p < .000001, Cohen's d = 0.18) and SF-36  factors. Thus, given that higher scores reflect higher quality of life, the VETERAN sample reported higher overall levels of subjective life quality on both the general and specific measures of QOL, when controlling for differences in the ways in which the two groups used the subscales to define QOL and for between-group differences in the reliabilities of the subscales.This final partially invariant multigroup CFA model fit the data of the two groups reasonably well. Inspection of the LISREL solution revealed that the latent means were significantly higher for the VETERAN sample, compared to the DOPPS sample, for both the KDCS  fit the data of both the VETERAN and DOPPS samples well, supporting configural invariance. We also tested a three-factor model using a single, second-order factor for the KDCS and two second-order factors for the SF-36  and found that although this three-factor model fit the data of both the DOPPS and VETERAN samples slightly better than our two-factor model, the SF-36 physical health component correlated very highly with the mental health component. These findings strongly suggest that a single second-order factor is a more appropriate way of modeling the SF-36 in the combined data analysis than is the two second-order SF-36 factors. In fact, when we attempted to model two second-order factors for the SF-36 in the combined analysis, it resulted in an inadmissible PHI matrix of factor correlations providing more evidence that only one second-order factor better represents the data. Our finding of a single second-order factor for the SF-36 data is consistent with other published studies. For example, in a study of 339 patients with Parkinson's disease, confirmatory factor analysis demonstrated evidence to support a single second-order factor for the SF-36 data but did not find evidence to support two second-order factors for physical and mental health components . EarlierAlthough the disease-specific HROQL (KDCS) and generic HRQOL (SF-36) components of the KDQOL-SF were highly correlated with one another, a one-factor model in which the KDCS and SF-36 represented overall HRQOL provided an unacceptable model fit, whereas a two-factor model fit the data reasonably well. These findings suggest that the KDCS and SF-36 measure two similar but distinct factors. It should be noted that the KDCS and HRQOL components were allowed, but not forced to correlate with one another. Our findings are consistent with several other studies demonstrating that generic measures of HRQOL and disease-specific measures make a unique contribution to the understanding of HRQOL ,80-82.As more than half of the data were missing for the sexual function scale of the KDCS, we did not include this subscale in our analysis. Other studies have also reported significant amounts of missing data for the KDCS sexual functioning subscale . A possiMultigroup CFA results concerning configural, metric, and scalar invariance suggested the partial strict invariance for the SF-36, but only weak invariance for the KDCS. Overall, these results support the conclusion that the SF-36 has more equivalent psychometric properties for the VETERAN and DOPPS samples than does the KDCS. Thus, the more general measure of HRQOL appears to provide greater measurement equivalence across samples than does the more specific measure of QOL related to kidney disease. The SF-36 has been more widely validated in different cultural groups than the more recently developed KDCS.The VETERAN sample tended to endorse higher scores on the same rating scales than the DOPPS sample, thus reporting higher overall HRQOL levels for both the generic (SF-36) and disease-specific (KDCS) factors. This finding is contrary to results of previous studies in which Veterans tend to report lower HRQOL than non-Veterans ,19. We sThe issue of how to interpret regression intercept differences between groups has been widely discussed in the literature -85. MillAn important question concerns whether observed group differences in item functioning reflect variation in "auxiliary" HRQOL factors or in unrelated "nuisance" factors -11. GiveOur study has several limitations. First, this study was restricted to males between the ages of 28 and 85 living in the United States. This restriction limits the generalizability of our findings to other CKD populations, including females. In addition, the exclusion criteria for the DOPPS and VETERAN data may have been different due to samples from different studies. Furthermore, data were collected from Veterans via telephone interview while data from non-Veterans were collected with a written questionnaire. It is possible that our findings are confounded by these different modes of data collection. Although there is no consensus in the literature related to comparability of data collected via written questionnaires and telephone interviews, several studies have demonstrated that mode of data collection has little to no effect on findings -89. In aVeterans make up a unique cultural group with life experiences in the military that may influence how they interpret HRQOL measures. These potential cultural differences must be considered when comparing perceived HRQOL ratings of Veterans to non-Veterans. Measurement invariance is an essential condition for valid comparisons of HRQOL rated by different cultural groups. Our data supported measurement invariance across Veterans and non-Veterans using the KDQOL-SF. However, structural invariance, a desirable but not necessary precondition for meaningful group comparisons, was not demonstrated, particularly with the KDCS, the disease-specific HRQOL component of the KDQOL-SF. Further evaluation of measurement invariance of the KDQOL-SF between Veterans and non-Veterans is needed using large, randomly selected samples before comparisons between Veterans and non-Veterans using the KDQOL-SF can be done reliablyCKD: Chronic Kidney Disease; DOPPS: Dialysis Outcomes and Practice Patterns Study; HRQOL: Health-Related Quality of Life; KDCS: Kidney Disease Component Summary; KDQOL-SF: Kidney Disease Quality of Life - Short Form.The authors declare that they have no competing interests.KLS-Conceptualized paper, contributed to data analyses, and wrote significant sections of manuscript, FBB-Performed data analyses and wrote significant portions of paper including Results section, DJR-Provided statistical consultation for primary study in which data for this paper was derived. Reviewed and commented on drafts of paper, KTS-Investigator for Veteran's study in which data for this study was derived. Reviewed and commented on drafts of paper.DMH-Senior author and Principal Investigator for the Veteran's study in which these data were derived. Reviewed and commented on drafts of paper.All authors have read and approved the manuscript.


Plastic is a broad name given to different polymers with high molecular weight, which can be degraded by various processes. However, considering their abundance in the environment and their specificity in attacking plastics, biodegradation of plastics by microorganisms and enzymes seems to be the most effective process. When plastics are used as substrates for microorganisms, evaluation of their biodegradability should not only be based on their chemical structure, but also on their physical properties . In this review, microbial and enzymatic biodegradation of plastics and some factors that affect their biodegradability are discussed. However, most conventional plastics such as polyethylene, polypropylene, polystyrene, poly(vinyl chloride) and poly, are non biodegradable, and their increasing accumulation in the environment has been a threat to the planet. To overcome all these problems, some steps have been undertaken. The first strategy involved production of plastics with high degree of degradability.i.e., plastics produced from fossil materials) or bio-based plastics . The inter-relationship between biodegradable plastics and bio-based plastics is shown in The word ‘bio-plastic’ is used confusingly. In our understanding, however, bio-plastics consist of either biodegradable plastics  and lactic acid  can be produced by fermentative biotechnological processes using agricultural products and microorganisms –3. BiodeThirdly, bold attempts are being made to recycle non-biodegradable plastics. For instance, polystyrene  can be recycled and used as filler for other plastics.Prior to the widespread applications of biodegradable plastics, it is important to evaluate and understand the mechanisms involved and the microorganisms that are associated with biodegradation. Regarding microbial and enzymatic degradation of plastics, we will discuss them from two sides: one aspect is based on microbial (enzyme) characteristics and the other is on characteristics of the plastics. Microbial (enzyme) characteristics imply distribution and kinds of microorganisms, as well as their growth conditions , and types of enzymes . An interesting question is, ‘what are the characteristics of plastics that can effectively promote the biodegradability of plastics?’ Usually our main focus has been on the chemical structure of polymers with respect to the biodegradability of water-soluble polymeric materials.When the biodegradability of solid polymers is assessed, aside from their chemical properties, we should also note their physical properties as polymer aggregates. In other words, we should consider not only the first order structures but also the high-order structures of polymers that play an important role in the biodegradation process. Furthermore, it is worth mention that surface conditions  of plastics also generally influence the biodegradation mechanism of plastics. In this review, we will be discuss the biodegradation of plastics by both microbial and enzymatic processes and several factors that govern their biodegradability.2.2 and H2O.Biodiversity and occurrence of polymer-degrading microorganisms vary depending on the environment, such as soil, sea, compost, activated sludge, etc. It is necessary to investigate the distribution and population of polymer-degrading microorganisms in various ecosystems. Generally, the adherence of microorganisms on the surface of plastics followed by the colonization of the exposed surface is the major mechanisms involved in the microbial degradation of plastics. The enzymatic degradation of plastics by hydrolysis is a two-step process: first, the enzyme binds to the polymer substrate then subsequently catalyzes a hydrolytic cleavage. Polymers are degraded into low molecular weight oligomers, dimers and monomers and finally mineralized to COStreptomyces and fungi n) is a pre-polymer of polyurethane. It is often blended with other polyesters to get specific desirable properties such as soft segments. PEA-degrading microorganisms were screened and isolated using PEA  as a sole source of carbon. Among the isolated PEA-degrading microorganisms, Penicillium sp. strain 14-3 exhibited the strongest activity. PEA was degraded in 120 h at high cell concentrations. This strain can degrade not only PEA but also aliphatic polyesters such as poly(ethylene succinate) (PES), PBS and poly(butylene adipate) (PBA) n) is a biodegradable synthetic partially-crystalline polyester with low melting point (60 °C) and a glass transition temperature (Tg) of −60 °C. It is prepared by ring-opening polymerization of ɛ-caprolactone. PCL has been shown to be degraded by the action of aerobic and anaerobic microorganisms that are widely distributed in various ecosystems. Furthermore, the degradation of high molecular weight PCL was investigated using Penicillium sp. strain 26-1 (ATCC 36507) isolated from soil. PCL was almost completely degraded in 12 days. This strain can also assimilate unsaturated aliphatic and alicyclic polyesters but not aromatic polyesters n) is a chemosynthetic biodegradable aliphatic polyester with good mechanical properties. The structural units of this polyester are similar to PHB and PCL, thus, it can be degraded both by PHB depolymerase and lipase n) and PES ([-O(CH2)2OOC(CH2)2CO-]n) are aliphatic synthetic polyesters with high melting points of 112–114 °C and 103–106 °C, respectively. They are synthesized from dicarboxylic acids  and glycols  n) is a natural polymer produced by many bacteria as a means to store carbon and energy. This polymer has attracted research and commercial interest worldwide because it can be synthesized from renewable low-cost feedstocks and the polymerizations are operated under mild process conditions with minimal environmental impact. Furthermore, it can be biodegraded in both aerobic and anaerobic environments, without forming any toxic products. Chowdhury reported for the first time the PHB-degrading microorganisms from Bacillus, Pseudomonas and Streptomyces species (PBS/C). This actinomycete has higher PHB-degrading activity than thermotolerant and thermophilic Streptomyces strains from culture collections n) is a biodegradable and biocompatible thermoplastic which can be produced by fermentation from renewable resources. It can also be synthesized either by condensation polymerization of lactic acid or by ring opening polymerization of lactide in the presence of a catalyst. This polymer exists in the form of three stereoisomers: poly(l-lactide) (l-PLA), poly(d-lactide) (d-PLA) and poly(dl-lactide) (dl-PLA). The manufacture of PLA from lactic acid was pioneered by Carothers in 1932 [PLA , thus, the PLA degrading microorganisms may probably identify the l-lactate unit as an analogue of l-alanine unit in silk fibroin. Several proteinous materials such as silk fibroin, elastin, gelatin and some peptides and amino acids were found to stimulate the production of enzymes from PLA-degrading microorganisms [Microbial degradation of PLA using a et al. . Since ta et al. . Many strganisms –54.Tritirachium album was the most effective for PLA degradation. Proteinase K and other serine proteases are capable of degrading l-PLA and dl-PLA but not d-PLA. Furthermore, proteinase K preferentially hydrolyzes the amorphous part of l-PLA and the rate of degradation decreases with an increase in the crystalline part [et al. reported that the degradation of PLA oligomers was accelerated by several esterase-type enzymes, especially Rhizopus delemar lipase [Amycolatopsis sp. was also capable of degrading casein, silk fibroin, Suc-(Ala)3-pNA but not PCL, PHB and Suc-(Gly)3-pNA [Williams  investigine part ,57. Fukur lipase . The purly)3-pNA . Their sl-PLA [It was reported that α-chymotrypsin can degrade PLA and PEA with lower activity on poly(butylene succinate-co-adipate) (PBS/A). Moreover, several serine proteases such as trypsin, elastase, subtilisin were able to hydrolyze l-PLA .6.6.1.The blending of biodegradable polymers is one approach of reducing the overall cost of the material and modifying the desired properties and degradation rates. Compared to copolymerization method, blending may be a much easier and faster way to achieve the desired properties. More importantly, through blending, other less expensive polymers could be incorporated with one another. Miscibility of the blends is one of the most important factors affecting the final polymer properties. Some of the advantages of producing miscible blends are: single phase morphology and reproducibility of the mechanical properties. However formation of miscible blends especially with non-biodegradable polymers can slow down or even inhibit the degradation of the biodegradable components.et al. developed blend plastics by combining PCL with conventional plastics such as low density polyethylene (LDPE), polypropylene (PP), polystyrene (PS), nylon 6 (NY), poly (PET) and PHB, and evaluated their enzymatic degradabilities. The blends of PCL and LDPE, PCL and PP retained the high biodegradability of PCL. In contrast, the degradability of the PCL part in the blends of PCL and PS, PCL and PET, PCL and PHB dropped off remarkably. In case of blends of PCL and NY or PS, the biodegradability of PCL did not change so much. In general, it seems that the higher the miscibility of PCL and conventional plastics, the harder the degradation of PCL on their blends by R. arrhizus lipase [Iwamoto s lipase . Furthers lipase  and PCL/s lipase  blends bAlcaligenes feacalis T1. Results showed that the weight loss of the blends decreased linearly with increase in the amount of PBA, PVAc or PCL [Different blends of PHB have been performed with biodegradable and non-biodegradable polymers and polysaccharides. The miscibility, morphology and biodegradability of PHB blends with PCL, PBA, and poly(vinyl acetate) (PVAc) were investigated. PHB/PCL and PHB/PBA blends were immiscible in the amorphous state while PHB/PVAc are miscible. Enzymatic degradation of these blends was carried out using PHB depolymerase from c or PCL .Koyama and Doi studied the miscibility, morphology and biodegradability of PHB/PLA blend. The spherulites of the blends decreased with an increase in the content of the PLA and the rate of enzymatic surface erosion also decreased with increasing PLA content in the blend. It was evident that polymer blends containing PHB usually showed improved properties and biodegradability when compared with pure PHB .l-PLA/PCL  were prepared and enzymatic degradation was observed using proteinase K or Pseudomonas lipase. Proteinase K was able to degrade the amorphous domain of PLA but not the crystalline part of l-PLA or PCL. On the contrary, Pseudomonas lipase can degrade both the amorphous and crystalline part of PCL, but not l-PLA [Different blends of ot l-PLA .6.2.Blends of synthetic polymers and starch offer cost performance benefits because starch is renewable, cheap and available year-round. In this case the starch blended can be in the form of granules or gelatinized starch or even starch which has been modified chemically to a thermoplastic. It is generally known that blends of PCL and granular starch exhibit a high degree of biodegradation .et al. developed PCL/gelatinized starch blends using corn starch acetates and evaluated their biodegradabilities by an enzyme, α-amylase. Their biodegradabilities rapidly decreased with an increase in PCL content [Takagi  content .et al. Both tensile strength and elongation of the blends decreased as the starch content increased. The blends were not good in tensile strength but were relatively good in elongation. Continuous phase dispersion of the starch in the PCL was observed in the films using SEM. Degradation of PCL/starch blends showed that as the starch content increased, the polymer blends became more biodegradable using lipase. This could be attributed to the increase in the surface area of PCL after blending with starch, thereby rendering it more susceptible to biodegradation [The feasibility of producing PCL/granular starch blends using different starch from cassava, sago and corn was reported by Pranamuda radation .et al. developed PCL/tapioca starch (granular and gelatinized) blends using poly(dioxolane), a poly, as compatibilizer. Their biodegradabilities by α-amylase increased as the starch content increased, but were independent of the dispersion of starch in the PCL matrix [Noomhorm L matrix .et al. investigated the interfacial adhesion between PLA and starch using MA and maleated thermoplastic starch (MATPS). Scanning electron microscopy (SEM) showed that MA is a good compatibilizer and PLA/starch blends had increased crystallinity. On the other hand, MATPS is not effective for PLA/starch blends. PLA/starch blends which were compatibilized with MA showed higher biodegradability than ordinary PLA/starch blends at the same PLA ratio [PLA and starch are good candidates for polymer blends because both are biodegradable and derivable from renewable resources. Starch can improve the biodegradability and lower the cost while PLA can control the mechanical properties of the blend. However, starch is a hydrophilic material, which does not interact well with hydrophobic polyesters resulting to unfavorable qualities of the blends. In line with this, several approaches have been proposed and developed to overcome the problem of incompatibility of starch and synthetic polymer blends ,70. VeryLA ratio .et al. Results showed that the tensile strength decreased with increase in starch content. Soil burial test showed that the rate of biodegradation increased significantly when the starch content was increased to 20%. It was confirmed that the molecular weight of PBS/A decreased after soil burial indicating that biodegradation was enhanced by the presence of starch [The properties and biodegradability of PBS/A and corn starch (5%–30% w/w) blends were investigated by Ratto f starch .7.et al. first reported the biodegradation of poly(ethylene carbonate) (PEC) implanted in dog tissue and suggested that pronase treatment might be effective in diminishing the PEC mass [et al. reported that PEC was degraded enzymatically in the peritoneal cavity of rats, but not with poly(propylene carbonate) (PPC) [Aliphatic polycarbonates are known to have greater resistance to hydrolysis than aliphatic polyesters. Imai PEC mass . Kawaguce) (PPC) .The distribution of PEC -degrading microorganisms seems to be limited, although PPC  appears to be non-biodegradable. The percentage of PEC-degrading microorganisms among total colonies ranged from 0.2% to 5.7% .et al. isolated poly(hexamethylene carbonate) -degrading microorganisms which were phylogenetically diverse. Roseateles depolymerans 61A formed di(6-hydroxyhexyl) carbonate and adipic acid from PHC, and di(4-hydroxybutyl)-carbonate and succinic acid from poly(butylene carbonate)  [et al. found that Amycolatopsis sp. HT-6 degraded high molecular-weight poly(butylene carbonate) . In a liquid culture containing 150 mg of PBC film, 83 mg of film was degraded after seven days cultivation [Suyama n 2,000) . Pranamutivation .Candida cylindracea, lipoprotein lipase from Pseudomonas sp., and lipase from C. cylindracea, Chromobacterium viscosus, porcine pancreas, Pseudomonas sp., and R. arrhizus degraded PBC (Mn 2000). Lipase and lipoprotein lipase from Pseudomonas sp. could also degrade high molecular-weight PBC . Lipoprotein lipase from Pseudomonas sp produced 1,4-butanediol, CO2 and di(4-hydroxybutyl) carbonate from PBC [Suyama and Tokiwa reported that a cholesterol esterase from from PBC .8.e.g., PCL-diol, polyethylene glycol, poly-tetramethylene glycol, and hard segments from the diisocyanate, e.g., 1,6-hexamethylene-diisocyanate (HDI), diphenylmethane-4,4’-diisocyanate (MDI), tolylene-2,4-diisocyanate (TDI), and diols such as ethylene glycol and butanediol.PU have various applications such as in the manufacture of plastic foams, cushions, rubber goods, synthetic leathers, adhesives, paints and fibers. There are two types of polyurethanes, that is, the ester type and the ether type. Most commercial polyurethane products are composed of soft segments derived from the polymer-diol, et al. found that R. delemar lipase and hog pancreatic lipase can hydrolyze the ES-PU composed of MDI, PCL-diol  and 1,4-tetramethylenediol (molar ratio 2:1:1). The amount of degradation products obtained from the ES-PU film with hog pancreatic lipase was approximately half of that produced by R. delemar lipase  after 24 h reaction. Hydrolysis rates of ES-PU containing either MDI or TDI were lower than that of ES-PU containing HDI. Thus, it was suggested that the rigidity of ES-PU molecules based on the aromatic rings, rather than the hydrogen bonds among the ES-PU chains, would influence their biodegradability by R. delemar lipase [Darby and Kaplan reported that polyester-type polyurethanes (ES-PU) were more susceptible to fungal attack than polyether-type polyurethanes (ET-PU) . Tokiwa r lipase .et al. reported on the degradation of an ES-PU and the secretion of an enzyme-like factor with esterase properties, by Curvularia senegalensis, a fungus isolated from soil [et al. showed that Comamonas acidovorans strain TB-35 was able to degrade ES-PU made from poly(diethylene adipate)  and TDI. A purified ES-PU-degrading enzyme from C. acidovorans TB-35, a type of esterase, hydrolyzed the ES-PU and released diethylene glycol and adipic acid [Crabbe rom soil . Subsequpic acid .et al. [et al. [Santerre et al.  and Wang [et al.  reportedHowever, it seems that no microbe can degrade polyurethane completely, and therefore, it is difficult to clarify the fate of residues after degradation of ES-PU by both microorganisms and enzymes. Furthermore, it is difficult to determine whether ET-PU itself was degraded by microbes to any significant extent.9.9.1.Flavobacterium sp. [Pseudomonas sp. (NK87) [Polyamide (nylon) has excellent mechanical and thermal properties, good chemical resistance and low permeability to gases, but it is known to be resistant to degradation in the natural environment. The poor biodegradability of nylon in comparison with aliphatic polyesters is probably due to its strong interchain interactions caused by the hydrogen bonds between molecular chains of nylon. Some microorganisms such as rium sp.  and Pseu. NK87)  have bee  have be9.2.et al. was able to isolate polyamide 4 degrading microorganisms (ND-10 and ND-11) from activated sludge. The strains were identified as Pseudomonas sp. The supernatant from the culture broth of strain ND-11 degraded completely the emulsified nylon 4 in 24 h and produced γ-aminobutyric acid (GABA) as degradation product [It has been reported that nylon 4 was degraded in the soil  and in t product .Generally speaking, degradation of polyamides is still unclear. Thus further investigations on the pathways of degradation are necessary.9.3.R. delemar lipase decreased with shortening of the nylon blocks in CPAE chains and with increasing nylon content. The simple blends of PCL and nylon retained high biodegradability of PCL. Thus it was assumed that the amount and distribution of hydrogen bonds, based on the amide bonds, in the CPAE chains influenced their biodegradability by this lipase [In order to improve the properties of biodegradable aliphatic polyesters for various fields of applications and to find the reason why industrialized aliphatic polyamides (nylon) are not biodegradable, CPAE were synthesized by the amide-ester interchange reaction between PCL and various nylons. The susceptibility of CPEA to hydrolysis by s lipase .et al. synthesized CPAE from ɛ-caprolactam with ɛ-caprolactone or δ-valerolactone by ring-opening copolymerization using Na catalyst under reduced pressure, and examined their degradation by R. arrhizus lipase. Most CPAEs were degraded by the lipase. The biodegradability decreased with an increase in Tm of CPAEs as a result of an increase in the amide bond contents [Komatsu contents .It would be very important that various types of interaction among macromolecular chains, which are related to Tm and storage modulus, are taken into consideration when designing the biodegradable solid polymers.10.Acinetobacter sp. 351 upon dispersion, while high molecular weight PE could not be degraded [PE is a stable polymer, and consists of long chains of ethylene monomers. PE cannot be easily degraded with microorganisms. However, it was reported that lower molecular weight PE oligomers (MW = 600–800) was partially degraded by degraded .Furthermore, the biodegradability of low density PE/starch blends was enhanced with compatibilizer . Biodegri.e., microorganisms). When PE is subjected to thermo- and photo-oxidization, various products such as alkanes, alkenes, ketones, aldehydes, alcohols, carboxylic acid, keto-acids, dicarboxylic acids, lactones and esters are released. Blending of PE with additives generally enhances auto-oxidation, reduces the molecular weight of the polymer and then makes it easier for microorganisms to degrade the low molecular weight materials. It is worthy to note that despite all these attempts to enhance the biodegradation of PE blends, the biodegradability with microorganisms on the PE part of the blends is still very low.Environmental degradation of PE proceeds by synergistic action of photo-and thermo-oxidative degradation and biological activity  among macromolecular chains affect not only the formation of polymer aggregates, but also the structure and physical properties and function (reactivity) of the polymer aggregates. The biodegradation mechanisms of plastics as shown in this review can be applied to biomass that are composed of polymeric materials .Biodegradable plastic is an innovative means of solving the plastic disposal problem from the standpoint of development of new materials. In general, plastics are water-insoluble, thermo-elastic polymeric materials. Biodegradability of plastics is affected by both their chemical and physical properties. Beside the covalent forces of polymer molecules, various kinds of weak forces  can be used as a model for abnormal protein, because it is easy to change their high order structures by quenching and elongation, etc. and to evaluate their rate of enzymatic degradation.Furthermore, knowledge about the biodegradation mechanisms of plastics would be useful for studies on protein conformational diseases that are associated with aggregation, deposition and crystallization of abnormal proteins such as Alzheimer’s disease and bovine spongiform encephalopathy (BSE). Proteinase K and Lipolytic enzymes such as lipase and esterase can hydrolyze not only fatty acid esters and triglycerides, but also aliphatic polyesters. We can understand that lipolytic enzyme has an important role in the degradation of natural aliphatic polyesters such as cutin, suberin and esteroid in the natural environment and animal digestive tract. However, it is not certain whether human body produces any aliphatic polyesters or not.


Early diagnosis of dengue virus (DENV) infection is important for patient management and control of dengue outbreaks. The objective of this study was to analyze the usefulness of urine and saliva samples for early diagnosis of DENV infection by real time RT-PCR. Two febrile patients, who have been attended at the General Hospital of the School of Medicine of Ribeirao Preto, Sao Paulo University were included in the study. Serum, urine and saliva samples collected from both patients were subjected to real time RT-PCR for DENV detection and quantification. Dengue RNA was detected in serum, urine and saliva samples of both patients. Patient 1 was infected with DENV-2 and patient 2 with DENV-3. Data presented in this study suggest that urine and saliva could be used as alternative samples for early diagnosis of dengue virus infection when blood samples are difficult to obtain, e.g., in newborns and patients with hemorrhagic syndromes. Infection with any of the four dengue virus serotypes can lead to a broad clinical spectrum, ranging from sub-clinical infection or an influenza-like disease known as dengue fever (DF) to a severe, sometimes fatal, disease characterized by hemorrhage and plasma leakage that can lead to shock, known as dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS),2. Labor2 flask containing a monolayer of C6/36 cells and seven days after inoculation, the supernatant was subjected to the real time RT-PCR to confirm virus isolation. Dengue virus was isolated from the serum samples collected two days after the onset of symptoms from both patients  and 13 (patient 2) years old, and presented symptoms suggestive of DF with high fever, frontal headache, arthralgia, myalgia and retro-ocular pain. The patients received supportive treatment including bedrest, antipyretics, analgesics and oral fluid replacement, and had a good outcome without any complication. Serum, urine and saliva samples were collected, two and nine days after the onset of symptoms, from both patients, and subjected to a quantitative real time RT-PCR for dengue as described earlier . Dengue  and 13 : Dengue virus; (DF): Dengue fever; (DHF/DSS): Dengue hemorrhagic fever/dengue shock syndrome; (RT-PCR): Reverse transcription-polymerase chain reaction; (NJ): Neighbor-joining; (hLTR): Hierarchical likelihood ratio test.The authors declare that they have no competing interests.TP and AO carried out the real time RT-PCR.HA and AA carried out the phylogenetic analysis.LG carried out the serological work.DP conducted the medical attention.TP and LF co-wrote and edited the manuscript.VA organized the overall project and helped edit the manuscript.All authors read and approved the final manuscript.


Congenital bradycardia-tachycardia syndrome is a rare disorder. Its association with multiple congenital anomalies/mental retardation (MCA/MR) syndrome is exceptional.2, SPO2, airway pressure) is essential as these patients are prone to develop pulmonary artery hypertension secondary to sleep apnea syndrome.We report a case of a new association of MCA/MR with bradycardia-tachycardia syndrome in an 18-year-old Indian man. This syndrome is characterized by mental retardation with delayed development of milestones, progressive scoliosis, cryptorchidism, asymmetrical limbs involving both the upper and lower limbs, sleep apnea syndrome, bradycardia-tachycardia syndrome and Dandy-Walker syndrome. Our patient was admitted for septoplasty with adenoidectomy. Patients with MCA/MR with bradycardia-tachycardia syndrome pose a unique challenge to the anesthesiologist. Establishing a good rapport with these patients is imperative. In addition to that, the anesthesiologist should anticipate the difficulty in intubation and rhythm abnormalities during the peri-operative period. Bradycardia or sinus arrest is a well-known complication during the induction and maintenance of anesthesia. Lignocaine should be used with caution in patients with bradycardia-tachycardia syndrome. Monitoring of ventilation parameters (end-tidal COBased on our clinical experience in detailed pre-operative evaluation and planning, we would emphasize peri-operative anticipation and monitoring for dysrhythmias in patients with MCA/MR and bradycardia-tachycardia syndrome undergoing any surgical procedure. Congenital bradycardia-tachycardia syndrome is a rare disorder . Its assAn 18-year-old Indian man was admitted for septoplasty with adenoidectomy. He was diagnosed as having MCA/MR syndrome, characterized by mental retardation with delayed development of milestones, progressive scoliosis, cryptorchidism, asymmetrical limbs that involve both the upper and lower limbs, supernumerary nipples (five), progressive myopia, obesity, sleep apnea syndrome, bradycardia-tachycardia syndrome and Dandy-Walker syndrome. His chromosomal study performed at the age of 5 was unremarkable  monitoring revealed bradycardia-tachycardia syndrome with sinus pauses  and isoflurane (1%). Standard intra-operative monitoring was adopted which included 5-lead ECG, non-invasive blood pressure, ETCO2, SPO2 and airway pressure. A 5.0 F sheath was inserted into the right internal jugular vein following induction of the anesthesia enabling insertion of the transvenous-pacing catheter in the event of bradycardia. Hemodynamic parameters were maintained within normal limits during the intra-operative period. Recovery from anesthesia was uneventful and his trachea was extubated at the end of the procedure. Postoperatively, the patient was intensively monitored for rhythm abnormalities. In the intensive care unit, he developed a fall in heart rate to 78/minute with sinus pauses, which was effectively treated with intravenous atropine. However, he did not require the temporary pacing during the peri-operative period. He was discharged from hospital 2 days later. During the follow-up period 1 month after the operation, the patient showed symptomatic improvement in upper airway obstruction.The patient was categorized as American Society of Anesthesiology (ASA) class 3, and general anesthesia was administered for the proposed surgery. Non-invasive transcutaneous pacemaker (NTP) paddles  were attached to his chest wall. Anesthesia was induced with propofol and fentanyl; tracheal intubation was achieved with rocuronium. A 7.0 mm cuffed endotracheal tube was inserted into his trachea without any difficulty. Anesthesia was maintained with an inhalational mixture of OBradycardia-tachycardia syndrome usually reflects the presence of sinoatrial disease, where episodes of supraventricular tachycardia complicate sinus bradycardia with or without periods of sinus arrest or sinoatrial block. Dizziness, syncope or convulsions may result from cerebral ischemia secondary to bradycardia, and tachycardia may cause palpitation, dyspnea and chest pain. The etiology of this syndrome is not known, but associations with coronary artery disease, thyrotoxicosis, cardiomyopathy, amyloidosis, diabetes and cardiac surgery have been reported . HoweverWe report the case of a patient with MCA/MR syndrome with bradycardia-tachycardia syndrome  scheduled for septoplasty with adenoidectomy. Patients with MCA/MR with bradycardia-tachycardia syndrome pose a unique challenge to the anesthesiologist. Establishing a good rapport with these patients is imperative. Anesthetic considerations include a) anticipation of difficulties in intubation due to restricted neck movements, short neck, and tracheal deviation; b) rhythm abnormalities during the peri-operative period; and c) adequate attention towards skeletal abnormalities, for example, scoliosis, as evident in this patient.Bradycardia or sinus arrest is a well-known complication during the induction and maintenance of anesthesia . This isOur patient had been diagnosed previously as having SAS. Patients with SAS are sensitive to all central depressant drugs, with upper airway obstruction or respiratory arrest occurring even with a minimal dose of sedatives, hypnotics or narcotics . Anesthe2, SPO2, airway pressure) is essential as these patients are prone to develop pulmonary artery hypertension secondary to SAS [Monitoring of ventilation parameters (ETCOy to SAS  or scoliBased on our clinical experience, we emphasize the importance of detailed pre-operative evaluation and planning, and peri-operative anticipation and monitoring for dysrhythmias in patients with MCA/MR and bradycardia-tachycardia syndrome undergoing any surgical procedure.MCA/MR: multiple congenital anomalies/mental retardation; ECG: electrocardiogram; SAS: sleep apnea syndrome; ASA: American Society of Anesthesiology; NTP: non-invasive transcutaneous pacemaker.Written informed consent was obtained from the patient's parents for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.The authors declare that they have no competing interests.CM provided patient care, acquisition of data and literature review. KM was involved in drafting the manuscript. PK was involved in patient care and interpretation of data.


Carpal tunnel syndrome (CTS) is a socially relevant condition associated with biomechanical risk factors. We evaluated age-sex-specific incidence rates of in-hospital cases of CTS in central/northern Italy and explored relations with marital status.score test) age-sex-specific rates between married, unmarried, divorced and widowed subsets of the general population. We calculated standardized incidence ratios (SIRs) for married/unmarried men and women.Seven regions were considered  over 3–6-year periods between 1997 and 2002 . Incidence rates of in-hospital cases of CTS were estimated based on 1) codified demographic, diagnostic and intervention data in obligatory discharge records from all Italian public/private hospitals, archived (according to residence) on regional databases; 2) demographic general population data for each region. We compared  of in-hospital cases of CTS were 166 in women and 44 in men . Married subjects of both sexes showed higher age-specific rates with respect to unmarried men/women. SIRs were calculated comparing married vs unmarried rates of both sexes: 1.59  in women, and 1.42  in men. As compared with married women/men, widows/widowers both showed 2–3-fold higher incidence peaks during the fourth decade of life .This large population-based study illustrates distinct age-related trends in men and women, and also raises the question whether marital status could be associated with CTS in the general population. Carpal tunnel syndrome (CTS) is a socially relevant work-related disabling condition ,2, with We evaluated age-sex-specific incidence rates of in-hospital cases of CTS in seven administrative regions of central/northern Italy. Based on data availability considerations and our interest in the possible role of household chores as a biomechanically plausible risk factor for CTS , we alsode jure marital status at the time of admission was available in terms of 'unmarried' (including cohabitant subjects), 'married' (including separated partners), 'widowed', or 'divorced' . Demographic general population data in each region (for each relevant year) were obtained from ISTAT  [In Italy, both public and private hospitals obligatorily provide individual discharge records–even for surgically treated day patients–containing codified demographic information  transcribed from identity cards that all residents are obliged to obtain from their local Municipalities, who in turn collate and regularly communicate their anagraphic data to The National Institute of Statistics (ISTAT). The information on each hospital discharge record is registered in databases of the patients' region of residence, irrespective of hospital location. During the periods under consideration, carpal tunnel release operations in Italy were almost invariably conducted on public/private hospital premises after severe chronic symptoms and positive nerve conduction studies. We reviewed the records of all patients with a principal diagnosis of CTS (ICD-9 code 354.0) in seven administrative areas Figure : Piemontalities) .score test [Zona Senese) considered in a previous study [We calculated age-sex-specific rates and standardized rates (age-adjusted by the Standard European Population proposed by the WHO) . Age-sexore test  was usedore test : standarus study  in correExcluding repeated admissions, 86,641 in-hospital cases of CTS were identified, 79% of whom  were women. At least 96%  of the patients received specific surgical treatment .The overall age-standardized incidence rate of in-hospital cases of CTS was 106.09 per 100,000 person-years , ranging from 49.64  in Alto-Adige/Südtirol to 132.47  in Umbria. The age-standardized incidence rate for women was 3.8-fold that for men: 166.27 per 100,000 person-years  vs 44.11 . Analogous sex-related differences were recorded in each region (data not shown). Figure Figure Comparison of clinically/electrodiagnostically diagnosed CTS rates in Siena  with theThis large population-based study of rates of in-hospital CTS in central/northern Italy reinforces our knowledge of age- and sex-related trends, and suggests that marital status might be associated with clinically/socially relevant chronic CTS.The overall age-standardized incidence rate of 106 in-hospital cases of CTS per 100,000 person-years is lower than the rate of 144 surgically treated cases per 100,000 reported for the state of Maine in 1993 ,16. Age-Analysis of data regarding Siena  suggestsAs regards marital status, married women and men in all age groups turned out to have higher SIRs as compared with their unmarried counterparts . Since married status has been associated with favourable levels of general health   are also intriguing. It will be interesting to see whether some or any of these trends are reproduced in different national settings.de jure marital status at the time of hospital admission. However, we are unable to think of any motive for inexact self-reporting .The ecological study design precluded analysis at an individual level. Elevated rates of CTS might also be attributed to general hospitalization trends related to marital status. We therefore examined the hospital discharge records of all patients hospitalized in Emilia-Romagna during the study period (excluding repeated admissions) with any principal diagnosis except delivery, complications of pregnancy or abortion (data not shown). Apart from the elderly (≥ 65 years) age group  showed only minor differences in distribution of white-collar workers versus blue-collar workers or housewives in the 'married' and 'unmarried' subsets of patients, which would not be sufficient to explain the differences in hospitalization rates (data not shown).Although the compulsory hospital discharge records are institutionally standardized, their reliability could be compromised by errors or omissions . However, there was a 96% concordance rate between the disease identification code (ICD-9) and the DRG code for carpal tunnel release . Since ISTAT does not provide information regarding 'separated' or 'cohabitant' marital status, it was not possible to take these factors into account in the analysis . Furthermore, the registration of patients' marital status only at the time of admission to hospital  could have led to a non-differential misclassification of exposure among patients who had recently changed status. These factors may have led to underestimates in the observed differences between rates associated with 'married' and 'unmarried' status. Due to number limitations, some of the age-sex-specific estimates for marital status showed wide 95% CI  rather than incidence of all clinically relevant cases of CTS. Knowledge of Italian practice during the period suggests that the hospital discharge records mainly correspond to highly symptomatic patients who eventually elected to undergo surgical treatment after several years of discomfort and positive nerve conduction study findings . This obIn summary, this large population-based study provides important confirmation of distinct age-related trends in men and women. Our findings also raise the question as to whether marital status could be associated with CTS in the general population. Studies in other national settings could explore this possibility. In the meantime, it should be underlined that our findings regarding marital status must be considered preliminary and merely hypothesis generating, especially given the absence in the present work of data regarding individual/occupational factors  and the lack of information about those cases of CTS which do not reach hospital treatment.The authors declare that they have no competing interests.SM, ABa and GC designed the study with SC, ABe, GdG, MdO, PFM, CM and MB.SM, ABa, ABe, GdG, MdO, PFM and CM were responsible for supervising data collection in the different centers. SM, SC and GC were responsible for data analysis. SM, SC and RMTC drafted the manuscript and contributed to interpretation, together with ABa, MB, EB, FZ and FSV. FSV supervised the entire work. All authors critically revised the manuscript. All authors read and approved the final manuscript.The pre-publication history for this paper can be accessed here:


High-sensitivity C-reactive protein (hs-CRP) is an easily measured inflammatory biomarker. This study compared the association of percent body fat mass (%FM), body mass index (BMI), waist circumference (WC), and waist-to-hip ratio (WHR) with hs-CRP in a Taiwanese population.A total of 1669 subjects aged 40-88 years were recruited in 2004 in a metropolitan city in Taiwan. The relationships between obesity indicators and a high level of hs-CRP were examined using multivariate logistic regression analysis. The upper quartile of the hs-CRP distributions was defined as the high category group. The areas under the curve (AUCs) of the receiver operating characteristic curves were calculated for all obesity indicators to compare their relative ability to correctly classify subjects with a high level of hs-CRP.After multivariate adjustment, the odds ratio for %FM was the only significant indicator that was associated with a high level of hs-CRP in men . All indicators were associated with a high level of hs-CRP in women. In men, the AUCs for %FM were significantly higher than those for BMI, WHR, and WC, when demographic and lifestyle behaviors were considered , but they were not significantly different in females.Our study demonstrates that %FM is the only obesity indicator that is strongly associated with a high level of hs-CRP after adjusting for sociodemographic factors, lifestyle behaviors and components of metabolic syndrome in both genders in a Taiwanese population aged forty years and over. In men, %FM had the greatest ability to classify subjects with a high level of hs-CRP when only demographic and lifestyle behaviors were considered. Our study finding has important implications for the screening of obesity in community settings. Obesity is a major public health problem in the world, affecting people in both developed and developing countries -4. AccorHigh-sensitivity C-reactive protein (hs-CRP), the main acute phase protein in humans, is a sensitive marker for systemic inflammation. Previous cross-sectional studies have shown that elevated hs-CRP levels correlate significantly with features of metabolic abnormality, including adiposity, hyperinsulinemia, insulin resistance, hypertriglyceridemia, and low high-density lipoprotein cholesterol (HDL-C) -13. AlthBody mass index (BMI) is an indicator of heaviness rather than fatness, and cannot distinguish body fat from fat-free mass. Waist-to-hip ratio (WHR) is a measure of regional fat distribution, whereas waist circumference (WC) is a measure of central obesity. Bio-electrical impedance analysis (BIA) produces a close estimate of fat-free mass throughout a wide range of body composition . BIA is This was a community-based cross-sectional study based on data from the Taichung Community Health Study. The detailed methodology has been described elsewhere -25. A to2 (m2). With the participant standing, WC was measured midway between the superior iliac crest and the costal margin, and hip circumference at its maximum protrusion point of the buttocks around the pelvis, and then the WHR was calculated as a measure of regional fat distribution. %FM was assessed by a body composition analyzer . The measurements were performed with the subjects stepping onto the measuring platform without shoes and after wiping the soles of their feet. The amount of body fat was expressed as a percentage of total weight. Previous studies have confirmed the validity of BIA in estimating body composition compared to dual energy X-ray absorptiometry (DEXA) [Anthropometric measurements and blood samples were obtained from the complete physical examination. Weight and height were measured on an auto-anthropometer , with the subjects shoeless and wearing light clothing. BMI was derived from the formula, weight (kg) ÷ (height)y (DEXA) ,26. The y (DEXA) . The pri® SST™ tube are the clot activator. Initial activation occurs when blood enters the tube and contacts the particles on the tube wall. Triglyceride levels were determined using an enzymatic colorimetric method. The interassay and intra-assay CVs for triglyceride were 6.8% and 5%, respectively. The HDL-C level was measured by a direct HDL-C method and the interassay and intra-assay CVs were 4.5% and 4.5%, respectively. The low-density lipoprotein cholesterol (LDL-C) level was also measured using a direct LDL-C method, and interassay and intra-assay CVs were 4.5% and 3%, respectively. The serum insulin level was measured by a commercial enzyme-linked immunosorbent assay kit . The interassay CV for insulin was 8.7% and the intra-assay CV was 3.4%. Insulin sensitivity was estimated with a Homeostasis Model Assessment (HOMA-IR) equation. The HOMA-IR equals fasting serum insulin (μU/ml) times fasting plasma glucose (mmol/l) divided by 22.5 [Blood pressure was measured by an electronic device  three times after the subjects had rested for 20 minutes. The lowest systolic and diastolic blood pressure was recorded. Blood was drawn from an antecubital vein in the morning after a 12-hour overnight fasting and was sent for analysis within four hours of blood collection. Hs-CRP levels were measured by nephelometry, a latex particle-enhanced immunoassay . The interassay and intra-assay CVs were <2.0% and <1.9%, respectively. The lower detection limit of the assay was 0.1 mg/L. Biochemical markers such as fasting plasma glucose, HDL-C, and triglyceride were analyzed by a biochemical autoanalyzer  at the Clinical Laboratory Department of China Medical University Hospital. Fasting plasma glucose was measured in blood obtained by use of NAF TUBE. NAF TUBE contains 5 mg sodium fluoride to inhibit glucose metabolism and 4 mg potassium oxalate to chelate calcium and prevent coagulation. The interassay and intra-assay CVs for fasting plasma glucose were 4% and 4%, respectively. We measured cholesterol and triglyceride in serum mode. A SST tube was used. The SST™ tube refers to the Serum Separator Tube containing clot activator and serum separator gel. The silica particles that coat the walls of the BD Vacutainer by 22.5 . The cut by 22.5 : elevateData regarding smoking, alcohol drinking, physical activity, betel nut chewing and family history of cardiovascular-related diseases were collected by questionnaire when the participants underwent a complete physical examination. Subjects who self-reported any of these characteristics  were placed into groups based on the specific characteristic. Those in the non-smoking group had never smoked or had smoked less than 100 cigarettes during their lifetime, whereas those in smoking group smoked currently or had smoked more than or equal to 100 cigarettes during their lifetime. Individuals who self-reported alcohol drinking, betel nut chewing or exercise were classified into the group with this specific characteristic. Those whose parents or siblings had a specific cardiovascular-related disease were classified as having a family history of the disease.Continuous variables were reported as means, whereas categorical variables were reported as numbers (percentage). The cutoff points for WC  were 90 A total of 1669 subjects (807 men and 862 women) were analyzed in the final model. The sociodemographic and anthropometric characteristics and biomarkers of the obese participants, as defined by %FM, BMI, WHR, and WC, and stratified by gender, are summarized in Tables Table 2 for overall test = 14.77, p = 0.002, the p values for pair-wise comparisons were all <0.001, Figure 2 = 5.55, p = 0.1355, Figure The AUCs and 95% CIs of four obesity indicators stratified by gender are shown in Table In this community-based study, we demonstrated that all obesity indicators, except WHR in men, were strongly associated with a high CRP level in Taiwanese men and women when sociodemographic factors and lifestyle behaviors were considered. Only the association for %FM remained significant in women after further considering individual abnormalities in the four components of MetS.Hs-CRP is an easily measured inflammatory biomarker and is released by the liver under the stimulation of cytokines, including interleukin-6, interleukin-1, and tumor necrosis factor-alpha. It has been shown hs-CRP has associations with endothelial dysfunction and insulin resistance syndrome . AlthougWHR has been the traditional anthropometric index for assessing central adiposity; however, the use of WC is gaining support -37 and pThe limitations of this study must be considered. The principal limitation relevant to the interpretation of our results is the use of cross-sectional data; thus, causal pathways underlying the observed relationships cannot be inferred. Second, these analyses were restricted to the first 1669 subjects entering the current study, indicating that potential selection bias might exist. To assess this possibility, we examined the demographic characteristics of the individuals with and without hs-CRP measurement by comparing age, sex, and administrative unit, and similar distributions were found. The non-differential distributions in age, sex, and administrative unit indicate this kind of selection error might be random, thus, the biased results in the effect may be toward the null, a lesser threat to validity.In summary, this study demonstrates that %FM is strongly associated with a high level of hs-CRP in both genders in a Taiwanese population aged forty years and over. The novelty of the study is that %FM is the only significant indicator related to hs-CRP among various anthrometric indexes in men when demographic and lifestyle behaviors, and the individual components of MetS are considered. This finding highlights the importance of %FM in screening obese individuals who have a higher likelihood of chronic inflammation, especially when no blood sample is drawn. BIA measurement offers a convenient and practical approach to body composition assessment and may be useful and valuable in community settings. Our study finding has important implications for the screening of obesity.hs-CRP: high-sensitivity C-reactive protein; HDL-C: high-density lipoprotein cholesterol; BMI: body mass index; WHR: waist-to-hip ratio; WC: waist circumference; BIA: bio-electrical impedance analysis; %FM: percent body fat mass; DEXA: dual energy X-ray absorptiometry; MetS: metabolic syndrome; ORs: odds ratios; AUCs: receiver operating characteristics curve.The authors declare that they have no competing interests.CCL, SLRK and TCL contributed equally to the design of the study and the direction of its implementation, including supervision of the field activities, quality assurance and control. CIL, CSL, WYL, MML, CCC, TL, CYH, WC and PCC supervised the field activities. CSL and YDL helped conduct the literature review and prepare the Methods and the Discussion sections of the text. TCL, SLRK, CIL, CSL, CCL, CHL and CWY designed the study's analytic strategy and conducted the data analysis. All authors read and approved the final manuscript.The pre-publication history for this paper can be accessed here:http://www.biomedcentral.com/1471-2458/10/579/prepub


We have compared the levels of creatine kinase (CK) activity and the distribution of CK isoenzymes determined by agarose gel electrophoresis in normal colon, liver and lung tissues, and in colon, liver and lung adenocarcinomas, lung squamous cell carcinomas and lung carcinoids. Colon and lung adenocarcinomas, and squamous cell carcinomas presented lower CK activity than the normal tissues and no differences were found between hepatocarcinoma and normal liver tissue. In contrast, lung carcinoids had higher CK activity than normal lung tissue. Type BB-CK was the predominant isoenzyme in normal lung, colon and liver tissues. Type MM isoenzyme was detected in normal lung and type MB-CK was found in normal colon. In most lung tumours the CK isoenzyme electrophoretic pattern did not change. However, no type BB-CK was detected in some hepatocarcinomas, type MM-CK decreased in lung carcinoids and type MB isoenzyme was not observed in colon adenocarcinomas. It is concluded that in most tumours there is a decrease in the expression of type B- and type M-CK subunits, whereas in lung carcinoid the expression of type B-CK activity increases. Thus, the increase in type BB-CK observed in the serum of patients with lung and colon adenocarcinomas is probably due mainly to enhanced enzyme release as a result of tumour cell necrosis.


Many parasitic organisms, eukaryotes as well as bacteria, possess surface antigens with amino acid repeats. Making up the interface between host and pathogen such repetitive proteins may be virulence factors involved in immune evasion or cytoadherence. They find immunological applications in serodiagnostics and vaccine development. Here we use proteins which contain perfect repeats as a basis for comparative genomics between parasitic and free-living organisms., a program for proteome-wide probabilistic description of perfect repeats in proteins. Parasite proteomes exhibited a large variance regarding the proportion of repeat-containing proteins. Interestingly, there was a good correlation between the percentage of highly repetitive proteins and mean protein length in parasite proteomes, but not at all in the proteomes of free-living eukaryotes. Reptile combined with programs for the prediction of transmembrane domains and GPI-anchoring resulted in an effective tool for in silico identification of potential surface antigens and virulence factors from parasites.We have developed Reptile .Systemic surveys for perfect amino acid repeats allowed basic comparisons between free-living and parasitic organisms that were directly applicable to predict proteins of serological and parasitological importance. An on-line tool is available at  Repetitive amino acid subsequences in polypeptides are of interest regarding the function as well as the evolution of proteins. At least 14% of all proteins contain internal repeats, the proportion being somewhat lower in prokaryote and higher in eukaryote proteomes . TypicalTrypanosoma brucei with over twenty Glu-Pro (EP-type), respectively five Gly-Pro-Glu-Glu-Thr (GPEET-type) repeats [Plasmodium falciparum with around forty Asn-Ala-Asn-Pro (NANP) repeats [Staphylococcus aureus, a determinant of staphylococcal sepsis with 83 Ser-Glu (SE) repeats [P. falciparum, T. brucei, Leishmania major, and other parasites now permits systemic approaches to repeat-containing proteins. Here we identify all proteins from pathogens that contain repeats and use them for comparative genomics between parasitic and non-parasitic species. All data and programs are freely accessible via the world-wide web.Pathogenic bacteria as well as eukaryotic parasites often possess surface proteins of repetitive nature, presumably to protect themselves against their hosts' defence responses ,23. Exam repeats ,25, the  repeats , or SdrE repeats . Such sh repeats , a malar repeats . Further repeats -35. The r) equals the number of possible sequences that contain the desired repeat, divided by the total number of possible sequences (20L).In order to scan whole proteomes for repeat-containing proteins, we created the tool Reptile. It uses a "brute-force" algorithm that detects all perfect repeats and enables direct calculation of a P-value. For each input sequence, Reptile generates all possible substrings from length 2 to a user-defined maximum (the default is 20) and counts their occurrences. After removing redundant repeats that are contained within longer ones, the repeated sequences are returned by ascending P-value. The probability P to find at least n repeats of length r in a random sequence of length L , switching signs with every increment according to the inclusion-exclusion principle [-5, corresponding to an expectancy of one false positive in 100'000 sequences). Direct repeats are marked. The P-value being independent of the actual sequence of a repeat, Reptile also returns a measure of whether a detected repeat consists of rare or frequent amino acids. This "Amino acid abundance measure" (AM) was defined as follows:Where rinciple . For prafi is the frequency in the corresponding proteome – respectively set of sequences submitted by the user – of the amino acid at position i of the repeat. AM is symmetric to zero, negative values indicating that a repeat predominantly consists of rare amino acids (and vice versa). Reptile is running on-line [Where r is the length of the repeat and  on-line  and acceCompared to other repeat-prediction programs Table  the main-10. Reptile was used to screen for such proteins in predicted proteomes from fully sequenced genomes. The median proportion of highly repetitive proteins was 2.7% in eukaryote proteomes and 0.43% in prokaryotes, confirming the notion [S = 0.51, p = 0.011). When distinguishing free-living from (endo)parasitic eukaryotes  while free-living eukaryotes showed no correlation at all , M. tuberculosis (2.9%) and Parachlamydia sp. (2.7%), and the lowest ones by Bacillus anthracis  and Streptococcus pyogenes  – however, it must be noted that with bacteria, the available genome sequences are biased towards pathogenic species. The most repetitive protein from eukaryotes was a hypothetical protein from the sleeping sickness parasite T. brucei, followed by the 11-1 gene product from P. falciparum, a known malaria antigen of more than 1 MD size [Streptococcus pneumoniae, the leading cause of pneumonia. Table Leishmania [Mycobacterium, an antituberculosis vaccine candidate [The eukaryote with the largest proportion of highly repetitive proteins,  MD size . The mosum bovis .0%, M. tishmania  or PGRS andidate . The preum bovis .0%, M. tandidate .-10 compared to the rest of the respective proteome. Overall, the amino acid composition of the repeats was more biased in eukaryotes than in bacteria , invariant surface glycoproteins (ISG) and even the variable surface glycoproteins (VSG), which contain a significant number of dipeptide repeats . In addition to these known proteins there was a large number of uncharacterized ones, particularly from P. falciparum which possesses hundreds of extremely repetitive transmembrane proteins .In order to predict which of the repeat-containing proteins are at the cell surface, Reptile was combined with Phobius , a progrei Table  indeed rNew specific and robust tests are urgently needed for the diagnosis of sleeping sickness, malaria, tuberculosis, and other neglected diseases ,46. PCR -10) proteins. Furthermore, the proportion of highly repetitive proteins correlates with mean protein length in parasites but not in the proteomes of free-living eukaryotes, illustrating the importance of amino acid repeats for parasites.Reptile's simple algorithm allows large-scale and quantitative description of perfect amino acid repeats. Originally designed to scan parasite proteomes for potential antigens and virulence factors, Reptile detects any protein of repetitive nature and thereby complements existing tools which work by self-alignment. Parasite proteomes vary considerably regarding the proportion of repetitive proteins, in contrast to those of free-living eukaryotes which all contain around 3% highly repetitive . Since the percentages of repeats in proteomes as well as the frequencies of amino acids were not normally distributed, non-parametric tests were used: Mann-Whitney test , WilcoxoThe repeat detection algorithm is described under Results. The program is written in C++ and the web-interface in Perl-CGI. Reptile uses sreformat from the HMMer package  to conveProject name: ReptileProject home page: Operating systems: Linux, UnixProgramming language: C++Licence: GNU GPLA Python script periodically runs Reptile, GPI-SOM, and Phobius over all new or updated proteome files of Integr8. The results are stored in a MySQL database. For sake of simplicity, for each protein only the repeat with the lowest P-value is stored. A Perl script is used to interconvert Fasta format and SQL. The web interface of Dora is written in PhP. The database and all the programs run on the vmware server of the Informatics Services of the University of Bern.The author(s) declare that they have no competing interests.NF developed all software and generated all the data. TN designed the MySQL database and created the user interface of Dora. JA derived the formula for the calculation of the P-value. NF and PM conceived the study, wrote the manuscript, and designed the figures. All authors read and approved the final manuscript.-10 of the same proteomes.Amino acid frequencies. Additional file Click here for file