His-bundle pacing (HBP) constitutes an excellent alternative to right ventricular pacing. Recently, several studies have reported on the success and efficacy of HBP in patients with left bundle branch block requiring cardiac resynchronization therapy. Nonetheless, HBP may not always be feasible due to high capture thresholds or disease in the distal His bundle. The present report discusses the utility and feasibility of pacing in the left bundle branch area located distal to the site of conduction block. Recently, several studies have reported on the feasibility and efficacy of HBP in patients requiring cardiac resynchronization therapy (CRT) and HBP has emerged as a viable alternative to biventricular pacing (BVP).5 However, while HBP is feasible in the majority of patients requiring ventricular pacing, it may be more challenging to implement in some individuals due to the existence of high His-bundle capture thresholds or an inability to correct underlying His-Purkinje conduction disease. In the present report, the case of a patient in whom distal conduction system pacing was implemented to overcome the challenges associated with permanent HBP is discussed.His-bundle pacing (HBP) is an excellent physiologic alternative to right ventricular (RV) pacing in patients requiring ventricular pacing. HBP has been shown to be associated with a significant reduction in the combined endpoint of mortality, heart failure hospitalization, and upgrade to biventricular pacing in comparison with RV pacing in patients with bradycardia and indications for permanent pacemakers.. Before her CRT operation, the patient had been on stable medical therapy, taking metoprolol 50 mg twice daily, lisinopril 20 mg daily, and furosemide 40 mg twice daily. Over the next two years, her LVEF had improved to 55% and remained stable, with an improvement in her NYHA functional status to class I. Her furosemide was subsequently discontinued. During the initial implantation, the LV lead  was implanted in a small- to medium-size lateral venous branch (excellent QLV), but with a capture threshold of 2 V at 0.5 ms. During follow-up, her LV capture threshold had steadily increased, likely as a result of proximal migration of the spiral-shaped lead. She underwent a generator change in 2012 due to battery depletion, at which time her LV capture threshold was 3.5 V at 1 ms. In 2018, she developed symptoms of exertional dyspnea, intermittent loss of LV capture at 6 V at 1.5 ms, and battery depletion and was referred for possible HBP.A 71-year-old female with longstanding dilated cardiomyopathy, a left ventricular (LV) ejection fraction (LVEF) of less than 20%, New York Heart Association (NYHA) functional class III status, and left bundle branch (LBB) block (LBBB) with a QRS duration of 190 ms had undergone CRT utilizing BVP about 10 years prior to presenting for the current case . However, following lead fixation, the pacing threshold to correct the LBBB was noted to be high at 2.5 V at 1 ms. Using the fluoroscopic HBP location as a reference, the sheath and lead were moved about 1 cm toward the RV apex, slightly posteriorly (inferiorly) . Unipolar pacing at this location resulted in the QRS morphology of a “W” pattern in lead V1, where a notch was noted at the nadir of the QS complex . The lead was rotated passively, while monitoring the unipolar pacing impedance and QRS morphology in leads V1 and V2. The pacing impedance progressively increased from 450 Ω to 780 Ω and the notch in the nadir of the QS complex in lead V1 moved up and toward the end of the QRS, resulting in a right bundle branch block (RBBB) morphology . Contrast injection through the sheath in a left anterior oblique 30° projection revealed the depth of the lead to be about 5 mm in the septum . The lead was advanced a few millimeters deeper by two additional rotations. At the final site, the paced QRS duration decreased from 155 ms at baseline to 118 ms . Pacing threshold at this site was 0.5 V at 0.5 ms, R-wave amplitude was 14 mV, and pacing impedance was 750 Ω. This site was accepted, the sheath was removed, and the lead was anchored to the pectoral fascia. The previously implanted coronary sinus lead was capped and the deep septal LBB area pacing (LBBAP) lead was connected to the LV port of a new biventricular implantable cardioverter-defibrillator.Following explantation of the defibrillator, left axillary venous access was obtained and a 7-French sheath was placed. A C315 His sheath  was advanced over a guidewire and placed in the tricuspid annular region. Using the SelectSecure 3830 pacing lead  and unipolar mapping, the distal His-bundle location was identified. The His–ventricular (HV) interval was 40 ms at this location. During pacing at an output of 5 V at 1 ms, there was significant narrowing of the QRS duration to 130 ms. Of note, there was also a significant decrease in the His to LV timing as measured in the coronary sinus pacing lead of from 174 ms to 99 ms, corresponding to a change in QLV  During follow-up, the patient felt significantly improved and her functional status returned to NYHA class I. A repeat echocardiogram performed at three months later revealed normal LV size and systolic function and an LVEF of 60% with no ventricular dyssynchrony. Her LBBAP lead threshold remained stable at 0.4 V at 0.5 ms.6 The patient described in this report was a classic super-responder to BVP with normalization of LV function along with significant structural  and electrical remodeling. Prior to BVP, her QRS duration in LBBB was 190 ms, which had decreased to 155 ms at the time of lead revision 10 years later. Review of her initial procedural report described a posterior venous branch with high capture thresholds and phrenic nerve stimulation, limiting her options for coronary sinus lead placement. Traditional alternative options for BVP include epicardial LV lead placement via thoracotomy or a video-assisted thoracoscopic procedure. Other approaches include placing the lead across the interatrial or interventricular septum into the LV endocardium or using the novel WiSE-CRT system  incorporating an LV endocardial microelectrode powered by ultrasound energy.8 Of course, these options are associated with technical challenges and additional procedural risks as well as a potential need for long-term antithrombotic therapy.CRT utilizing BVP has become a well-established option for the management of patients with cardiomyopathy, reduced LVEF, and LBBB. Super-response to CRT can occur in up to 30% of patients, especially in women with nonischemic cardiomyopathy.9 However, in about 25% of patients with LBBB, HBP may not be able to correct the conduction abnormalities with an acceptable capture threshold. In the current patient, HBP resulted in the correction of LBBB, albeit at high capture thresholds, so it was not accepted as a feasible treatment option. It has recently been demonstrated that pacing the LBB distal to the site of conduction block in the His bundle is feasible and associated with excellent pacing thresholds.10 This is not technically challenging or associated with high morbidity as compared with the alternative approaches discussed above. In patients with complete LBBB, Purkinje potentials may not be recorded despite the lead being placed at the LBB area. However, if HBP results in the correction of LBBB, then potentials may be recorded, confirming the lead to be in the LBB area. Vijayaraman et al. recently demonstrated that it is possible to record the LBB potentials in patients with LBBB when conduction occurs through the LBB  or if an escape beat originates from the LBB.11Recent reports have demonstrated that the application of HBP in patients with typical LBBB and nonischemic cardiomyopathy can result in normalization of the LVEF in more than 80% of patients.. Early experiences with LBBAP in patients with dilated cardiomyopathy and LBBB suggest remarkable electrical resynchronization associated with excellent clinical and echocardiographic response.12 LBBAP is correlated with excellent capture thresholds as compared with HBP or LV pacing via coronary sinus branches. In addition to being able to achieve a low and stable capture threshold, LBBAP is also an attractive option for pacing in patients with infranodal conduction disease while still maintaining LV synchrony.11 The long-term implications of LBBAP need to be carefully studied for a better understanding of both clinical outcomes and safety concerns. Nonetheless, LBBAP represents a natural evolution of His-Purkinje conduction system pacing to overcome the challenges posed by the current limitations of HBP.LBBAP was easily achieved in the present patient using the same delivery sheath and lead employed for HBP. While an LBB potential was not recorded in this case, pacing from this site resulted in a significant narrowing of QRS duration from 155 ms to 118 ms, suggesting engagement of the conduction system. More importantly, the local activation in the previously implanted LV lead as measured by the QLV interval served as an excellent surrogate for LV activation. During LBBAP, the stimulus-to-LV interval decreased significantly to 84 ms versus the baseline QLV of 134 ms, confirming the existence of electrical resynchronization by rapid activation through the Purkinje network


Background: The utility of ANCA testing as an indicator of disease activity in ANCA-associated vasculitis (AAV) remains controversial. This study aimed to determine the association of ANCA testing by various methods and subsequent remission and examine the utility of a widely used automated addressable laser-bead immunoassay (ALBIA) to predict disease relapses.Methods: Data from the Rituximab vs. Cyclophosphamide for ANCA-Associated Vasculitis (RAVE) trial were used. ANCA testing was performed by direct ELISA, capture ELISA, and ALBIA. Cox proportional hazards regression models were used to evaluate the association of PR3-ANCA level and subsequent remission or relapse. The ALBIA results are routinely reported as >8 when the value is high. For this study, samples were further titrated. A decrease and increase in PR3-ANCA were defined as a halving or doubling in value, respectively.Results: A decrease in ANCA by ALBIA at 2 months was associated with shorter time to sustained remission . A decrease in ANCA by direct ELISA at 4 months was associated with decreased time to sustained remission . There were no other associations between ANCA decreases or negativity and time to remission. An increase in PR3-ANCA by ALBIA was found in 78 of 93 subjects (84%). Eleven (14%) had a PR3-ANCA value which required titration for detection of an increase. An increase of ANCA by ALBIA was associated with severe relapse across various subgroups.Conclusions: A decrease in ANCA by ALBIA at 2 months and by direct ELISA at 4 months may be predictive of subsequent remission. These results should be confirmed in a separate cohort with similarly protocolized sample and clinical data collection. A routinely used automated ALBIA for PR3-ANCA measurement is comparable to direct ELISA in predicting relapse in PR3-AAV. Without titration, 14% of the increases detected by ALBIA would have been missed. Titration is recommended when this assay is used for disease monitoring. The association of an increase in PR3-ANCA with the risk of subsequent relapse remains complex and is affected by disease phenotype and remission induction agent. The antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAV) are characterized by necrotizing inflammation affecting predominantly small vessels . Three cHistorically, the course of AAV was inevitably fatal. The advent of treatment with immunosuppressive regimens such as cyclophosphamide (CYC) or rituximab (RTX), in combinationwith glucocorticoids (GCS), changed this course to one of a chronic relapsing disease. Remission is achievable with induction therapy in 70–90% of patients but more than half of patients in remission are at risk for relapse, particularly if they have ANCA reacting with proteinase 3 (PR3-ANCA) –10.Ever since the discovery of ANCA, the utility of ANCA testing as an indicator of disease activity or prediction tool of relapse has been investigated with conflicting results –34. To dSerum samples and clinical data from the Rituximab vs. Cyclophosphamide for ANCA-Associated Vasculitis (RAVE) trial were used . All pat2 or oral CYC of 2 mg/kg/day for 3–6 months followed by Azathioprine (AZA) to month 18. All patients received GCS consisting of intravenous methylprednisolone followed by a prednisone taper. The follow-up protocol consisted of visits at baseline; then weekly for 4 weeks, then monthly until 6 months, then every 3 months until month 18. Subsequently, patients were seen every 6 months until trial closeout which occurred 18 months after the last patient was enrolled. Additional study visits occurred at the patients' and providers' discretion, usually in the case of disease relapse or serious adverse event  for PR3-ANCA and MPO-ANCA (supplied by Euroimmun) on all baseline serum samples . If founA PR3-ANCA test result obtained by ALBIA is considered equivocal if a value of 0.4–0.9. In this study, if a value was within the equivocal range the presence of a cANCA pattern was confirmed by immunofluorescence. This method increases the sensitivity of the ALBIA assay without compromising specificity. Results of the ALBIA assay are routinely reported to a value of 8 units, after which it is reported as >8 units. For this study, samples were additionally titrated 1:1, 1:4, 1:10, and 1:100 with the highest value recorded. If a value was not titrated, then the first titrated value was used. An increased PR3-ANCA level was defined as doubling in value compared to the lowest visit in the last 6 months. A decreased ANCA level was defined as halving of value compared to the highest visit in the last 6 months. All changes were outside the intra-assay and inter-assay coefficients of variation.Statistical analyses were completed using SAS, version 9.3 (SAS Institute). Descriptive data are reported as mean (SD), median and percentages.n = 108) whether achieved on originally assigned treatment or after cross-over. Cox proportional hazards models were used to assess whether ANCA level decreases were associated with subsequent remission. Analysis was completed looking at ANCA decrease for the event of interest of complete remission or sustained remission. To examine whether a decrease in ANCA was associated with remission, the times of interest were 2 and 4 months after enrollment in the study (time 0). Patients were classified according to their ANCA as “decrease” or “no decrease” Patients classified as “no decrease” included all patients that did not meet criteria for a decrease as defined as halving of ANCA value including those who had an increase in ANCA, had stable ANCA levels and had a decrease in ANCA that did not meet criteria. Time to complete remission and sustained remission were then estimated by using the Kaplan-Meier method.This analysis was based on all patients who achieved complete remission following remission induction therapy . Cox proportional hazards models were also used to assess whether PR3-ANCA level increases were associated with subsequent relapse. This analysis was completed looking at a rise in PR3-ANCA for the event of interest of “any” relapse and “severe” relapse. Hazard ratios with corresponding 95% confidence intervals were used to quantify the increase in risk of relapse within 12 months after a PR3-ANCA increase. In order to determine the accuracy of the model to discriminate patients at increased risk of relapse, c-indices were calculated as was completed in a previous study ; therefore, with an increase in one an increase in the other is expected, and the opposite is true   . In patiA decrease in PR3-ANCA at 4 months occurred in 101 (77%), 68 (52%), and 121 (92%) of patients by direct ELISA, capture ELISA, and ALBIA, respectively. A decrease in PR3-ANCA by direct ELISA at 4 months was associated with decreased time to sustained remission   with a mPR3-ANCA negativity occurred at 4 months in 74 (56%), 41 (31%), and 55 (42%) patients by direct ELISA, capture ELISA and ALBIA, respectively. There was no association between PR3-ANCA negativity at 4 months by any PR3-ANCA assay and time to complete or sustained remission .When stratified by treatment group there was an association between a decrease in PR3-ANCA by ALBIA at 2 and 4 months and time to sustained remission in patients treated with CYC/AZA .A decrease in PR3-ANCA by direct or capture ELISA at 4 months was associated with decreased time to complete remission in patients with granulomatous disease . There wThe baseline characteristics of the 93 PR3-ANCA positive patients who achieved complete remission have been reported elsewhere . RelapseOf the 15 patients who did not experience an increase in PR3-ANCA, 8 (53%) developed a subsequent relapse . Additiop = 0.002). This association was true for the subgroups of patients with renal involvement, capillaritis, diffuse alveolar hemorrhage, and those treated with RTX  did not experience a severe relapse during follow-up.This study reconfirms that different ANCA detection assays perform differently when applied in clinical practice. This is why it is important for clinicians to know how each assay performs. The differences between assays are most likely the result of the PR3 antigen being presented differently in the solid phase in the different assays. Since ANCA are polyclonal antibodies it is not surprising that these antibodies recognizing different epitopes bind differently in the various assays which present the antigen in different fashions. This is why it is important to know what assays can be used clinically. The current findings expand the acceptable PR3-ANCA testing methods for disease monitoring to include the more convenient, routinely used automated ALBIA technology. It is important to note that without titration of the ALBIA values, 14% of the increases detected would have been missed. It is therefore strongly suggested that the serum samples be titrated when the automated ALBIA is used for AAV disease monitoring. In this study values considered equivocal in the ALBIA assay (0.4–0.9) had the cANCA pattern confirmed by immunofluorescence. Confirmation by immunofluorescence or another ANCA assay should be completed for equivocal values if using the ALBIA assay as a high-volume screening assay to increase the sensitivity without compromising specificity.There are several limitations to this study. Classifications of disease phenotype and severity of relapse were based on BVAS/WG forms completed during the RAVE trial by expert clinicians. This data was unable to be verified at the time of this study. Disease phenotype was classified based on disease activity at baseline and not adjusted for changes in phenotype at relapse. The intervals of ANCA measurement were in accordance with the RAVE study protocol . For theA PR3-ANCA decrease by ALBIA at 2 months was associated with decreased time to sustained remission and may be predictive of refractory disease. Measurement of PR3-ANCA by ALBIA at 2 months may help clinicians identify those patients who will not respond to the current therapy. Clinicians should consider changing to an alternative therapy or close monitoring of patients without a decrease in PR3-ANCA by ALBIA at 2 months. ALBIA for PR3-ANCA measurement is comparable to direct ELISA in predicting relapse in PR3-AAV. Therefore, ALBIA which is a widely used ANCA assay in many high-volume laboratories can be used for serial ANCA testing for disease monitoring with no need to change to direct ELISA for disease monitoring. It is important to note without titration, 14% of the increases detected by ALBIA would have been missed. Consequently, titration is recommended when this assay is used for disease monitoring in AAV. Our study has limitations, and the results should be confirmed in a separate cohort. The association of an increase in PR3-ANCA with the risk of subsequent relapse remains complex and is affected by disease phenotype and remission induction agent. Individual patient factors need to be considered when applying this information clinically.The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.The studies involving human participants were reviewed and approved by Institutional Review Board, Mayo Clinic, Rochester, MN. The patients/participants provided their written informed consent to participate in this study.GT completed data organization and analysis, writing of manuscript. AH, FS, and MS generated the ANCA data. DS completed statistical analysis, generation of tables. LF, CL, PMe, PMo, PS, RS, ES, JS, and US were involved in the RAVE trial design and completed the clinical data collection. US designed the present project, completed data collection, writing of manuscript. All authors were involved with editing the manuscript and approved the final version.The authors declare that this study received funding from Genentech, Inc. and Biogen IDEC, Inc. The funders were not involved in the study design, collection, analysis, interpretation of data, the writing of this article or the decision to submit it for publication.


To assess the effect of lockdown during the 2020 COVID-19 pandemic on daily all-cause admissions, and by age and diagnosis subgroups, and the odds of all-cause mortality in a hospital in rural KwaZulu-Natal (KZN).Observational cohort.Referral hospital for 17 primary care clinics in uMkhanyakude District.5848 patients contributed to 6173 admissions.Data collected by the Africa Health Research Institute on all admissions from 1 January to 20 October: Five levels of national lockdown in South Africa from 27 March 2020, with restrictions decreasing from levels 5 to 1, respectively.Changes and trends in daily all-cause admissions and risk of in-hospital mortality before and at each stage of lockdown, estimated by Poisson and logistic interrupted time series regression, with stratification for age, sex and diagnosis.Daily admissions decreased during level 5 lockdown for infants (incidence rate ratio (IRR) compared with prelockdown 0.63, 95% CI 0.44 to 0.90), children aged 1–5 years old  and respiratory diagnoses . From level 4 to level 3, total admissions increased , as well as for men >19 years  and respiratory diagnoses . Among patients admitted to hospital, the odds of death decreased during level 5 compared with prelockdown  and then increased in later stages.Level 5 lockdown is likely to have prevented the most vulnerable population, children under 5 years and those more severely ill from accessing hospital care in rural KZN, as reflected by the drop in admissions and odds of mortality. Subsequent increases in admissions and in odds of death in the hospital could be due to improved and delayed access to hospital as restrictions were eased. Interrupted time series regression provides original insight into the impact of COVID-19 lockdown on hospital admissions and mortality in South Africa.This paper complements recently published evidence from the same catchment to give a fuller picture of access to multiple levels of healthcare in one population.Hospital data provide only indirect evidence of access to hospital care and reasons for changes in access.Using data from one hospital in a rural, low-middle-income setting in South Africa limits generalisability to other settings.Small sample limits statistical power to detect changes in subgroups.The COVID-19 global pandemic has caused huge disruption to health systems worldwide. As the number of cases of the novel coronavirus rose throughout 2020, health systems focused resources on to COVID-19. This led to global reductions in resources for non-COVID-19 services.5–7The effects of these measures on progress to reach universal health coverage globally are largely unknown, but it is likely that progress in low-income and middle-income countries was adversely affected due to weak and under-resourced health systems serving populations with high burden of both communicable and non-communicable diseases, as well as social and economic deprivation.9–11A potential consequence of lockdowns is reduced utilisation for non-COVID-19 conditions. Excess mortality during the pandemic that is not explained by direct mortality from COVID-19 supports this concern.14–17South Africa implemented a level 5 lockdown order at midnight of 26 March 2020.Lockdown restrictions applied nationwide, including the KwaZulu-Natal province, despite COVID-19 cases and deaths only increasing after the end of MayIn this study we investigated the effects of the lockdown measures during the COVID-19 pandemic on admissions to and deaths in the referral hospital serving the same clinics and population as the latter study. We focused particularly on admissions in subgroups stratified by age, sex and diagnosis as indicators of access to hospital care. We also compared the risk of in-hospital mortality before and after lockdown as an indicator of the severity of presenting illnesses. We hypothesised that lockdown measures would lead to reduced hospital admissions due to reduced mobility and would increase as lockdown restrictions were eased. We also hypothesised that risk of in-hospital mortality would increase if people with less severe illness were selectively deterred from going to hospitals or would decrease if those with more severe illness were selectively deterred.We performed secondary analysis of data collected by the Africa Health Research Institute (AHRI), located in a subdistrict of northern KwaZulu-Natal, uMkhanyakude District in South Africa. It is a largely rural district which is socioeconomically deprived, falling in the bottom 10 of all districts in South Africa in terms of education levels, employment, access to piped water and sanitation at home.25Data for each admission were captured prospectively by AHRI clinical research workers based in the hospital. These include demographic data of each patient, as well as admission, discharge and death diagnoses, coded according to the International Classification of Diseases (ICD-10) by trained nurses and recorded on an electronic database.Total admissions for the study period were stratified by age, sex and discharge diagnosis to demonstrate the typical case-mix at the hospital. To identify suitable regression models for estimating the effects of lockdown, we first graphically plotted the number of daily admissions and probability of death over time with locally weighted scatterplot smoothing (LOWESS).We used interrupted time series linear regression to estimate the effects of lockdown on the number of daily admissions to hospital. We first calculated the number of admissions each day then analysed the aggregated data at day level. These analyses were carried out for all admissions and for subgroups defined by age, sex and diagnosis. We used two sets of regression models to estimate the effect of lockdown on hospital utilisation, one estimating step changes in daily admissions or odds of death during each level of lockdown compared with prelockdown, and the other estimating linear time trends over the entire lockdown period.To estimate absolute changes in the mean number of daily admissions between each level of lockdown, compared with the prelockdown period, we used the following model:5, L4, L3, L2 and L1L are binary dummy variables indicating each stage of lockdown, and their coefficients  of daily admissions between each level of lockdown are shown in However, there were statistically significant changes among subgroups of patients. Daily admissions decreased significantly during level 5 lockdown for infants , children aged 1–5 years old  and respiratory diagnoses . In infants this represents a reduction in the incidence rate from 1.46 to 0.91 admissions per day, which did not recover by the end of the study, with 0.42 admissions per day during level 1 lockdown. The same trend was seen in children aged 1–5 years old, with an incidence rate before lockdown of 1.07 per day, reducing to 0.43 admissions per day during level 5, and not recovering by level 1 with an incidence rate of 0.61 per day. The most common reasons for admission in infants were neonatal conditions (42.6%), gastroenteritis (18.6%) and pneumonia (9.5%). In children aged 1–5 years old they were injuries (32.1%), gastroenteritis (15.0%) and pneumonia (10.6%).From level 4 to level 3, admissions increased significantly for men aged over 19 , individuals 20–45 years old  and respiratory diagnoses .From level 2 to level 1, admissions decreased significantly for maternal and neonatal diagnoses , NCDs  and injuries . As a sensitivity analysis, admissions from 1 October onwards were excluded to test if this finding was due to data collection or upload delays in ICD-10 coding. The decrease seen in NCDs persisted but became non-significant . Maternal and neonatal admissions no longer decreased . Admissions for injuries continued to decrease . There were no statistically significant changes in these subgroups during the earlier stages of lockdown. Daily number of admissions in individuals aged 6–19, 45–65 and over 65 years old and for adult women and CDs did not change significantly at any stage of lockdown.Linear regression models of these step changes produced similar results . Residua10.1136/bmjopen-2020-047961.supp2Supplementary dataAmong patients admitted to hospital, the odds of death decreased substantially and significantly during level 5 lockdown compared with prelockdown , then increased from level 5 to level 4 , did not change from level 4 to level 3 , increased from level 3 to level 2 , and then did not change during level 1 . These cSensitivity analysis with adjustment for calendar month, including admissions from the start of 2019, did not substantially alter the direction of changes in daily admissions or effect size seen during lockdown. For example, admissions in children aged 1–5 still decreased significantly at level 5 lockdown  when data from 2019 were included in analysis. However, these results are not included as LOWESS plots identified an overall decrease in admissions since the start of 2019 and this may have exaggerated the effect size seen during lockdown.In this analysis of hospital admission and hospital mortality in a mostly rural South African setting, national lockdown was not associated with reductions in all-cause daily admissions. Total admissions, and of adult men, increased from level 4 to level 3. Numbers of admissions in adult women, individuals over 45 years old and 6–19 years old, and for CDs were mostly unchanged after lockdown. However, admissions for children under 5 fell sharply during level 5 lockdown and remained low. During the final level 1 lockdown, admissions for maternal and neonatal conditions, NCDs and injuries dropped significantly compared with level 2, despite no significant changes during the earlier levels of lockdown. Risk of in-hospital mortality halved during level 5 lockdown then increased to prelockdown rates.These observed changes could be due to changes in the health of the local population, or to lockdown restrictions, or both. However, the magnitude of changes over a relatively short period and the small number of reported COVID-19 admissions suggest that changes in access to hospital care are likely to have been influential. Reduced access to hospital during lockdown could be due to a combination of factors including mandatory restrictions on movement, fear of being infected and inability to pay for transport due to lost income . Availability of ambulance transport from home to hospital is limited. Expense of transport and travel time are known barriers to care in this population and are likely to have been exacerbated by restrictions on public transport during lockdown.27 28Our findings that all-cause hospital admissions did not fall but that admissions of children under 5 years old decreased were consistent with findings of Siedner and colleaguesSimilar reductions in paediatric admissions for respiratory disease were reported during the early pandemic in China, and decreased emergency department attendance was reported in Victoria, Australia.These results suggest that admissions for individuals over 45 years old, CDs and injuries remained stable despite the significant restrictions during lockdown. This is unlike other regions in South Africa which saw reductions in surgical admissions in the North West Province and prenatal antiretroviral pre-exposure prophylaxis visits in the Western Cape.35 36The KwaZulu-Natal provincial health department reported that by 11 April the cumulative incidence of COVID-19 in uMkhanyakude District was 21, with no deaths.A possible explanation for the increase during level 3 could be migration into the area, if urban workers moved back to their rural homes when transport restrictions eased during level 3 lockdown.36 40A major finding of this study is the large reduction in all-cause mortality during level 5 lockdown, despite resilience in admission numbers overall. This supports our hypothesis that the sickest people may have been disproportionately unable to access hospital care as needed and died at home as opposed to hospital, or presented late to hospital, resulting in increasing mortality from level 4 onwards. Reductions in numbers of admissions in the sickest may have been offset by the observed increases in admissions of younger, healthier adults. The South African Medical Research Council reported 7729 excess deaths in KwaZulu-Natal from 6 May to 10 November 2020, compared with the same dates during previous years, which was much more than the number of COVID-19 cases reported.Limitations of this study include only analysing admissions up until 20 October 2020, before the pandemic had resolved globally and the second waves of COVID-19 cases were beginning.Further work should focus on the impact of COVID-19 on access to children’s health services. They appear to have a lower risk of acquiring and suffering from severe COVID-19,


The coronavirus disease 2019 (COVID-19) pandemic has caused major disruption to medical education for student doctors in the United Kingdom (UK). This has led to widespread cancellations and postponement of clinical placements, electives and examinations.On March 24, 2020, the UK Government announced that 5500 final-year medical students would have the option of joining the National Health Service (NHS) workforce early to offer additional support and help relieve the increasing strain put on clinical services by the spread of COVID-19 .We sought to determine the thoughts of UK medical students regarding their willingness to be placed in clinical environments during the COVID-19 outbreak. Medical students across the UK were invited in the period between March 13 and March 26, 2020, via social media, to participate in an online survey; 206 students completed the survey (Appendix S1 of the 62.6% (n = 129) of students said they would be willing to attend clinical placements during the COVID-19 outbreak. 58.1% (n = 75) of this group said they were willing to be on the wards despite feeling it would be an unsafe environment for them.With regards to mitigating risks for medical students, 69% (n = 144) felt that their medical school had taken adequate measures to reduce their exposure to COVID-19. The remaining 31.1% (n = 64) highlighted frustrations surrounding a delayed response in offering specific advice regarding working in clinical environments and reducing the risk of exposure to the virus. Multiple responses demanded clearer guidelines from their medical schools and instructions for the appropriate use ofPPE. The majority  agreed there have been measures put in place by the medical school to reduce their risk of exposure to the virus (This survey suggests that despite concerns surrounding safety and risk of exposure to COVID-19, most UK medical students were willing to work in clinical environments. This may have translated into a significant number of final-year medical students taking up the opportunity to support the NHS during the pandemic.


The evaluation shows significant improvement over the base model without bidirectional ammonia flux. Comparisons to monthly average satellite retrievals show similar spatial distribution with the highest ammonia concentrations in the Central Valley of California (CA), the Snake River valley in Idaho, and the western High Plains. In most areas the model underestimates, but in the Central Valley of CA, it generally overestimates ammonia concentration. Case study analyses indicate that modeled high fluxes of ammonia in CA are often caused by anomalous high soil ammonia loading from EPIC for particular crop types. While further improvements to parameterizations in EPIC and CMAQ are recommended, this system is a significant advance over previous ammonia bidirectional surface flux models.Ammonia surface flux is bidirectional; that is, net flux can be either upward or downward. In fertilized agricultural croplands and grasslands there is usually more emission than deposition especially in midday during warmer seasons. In North America, most of the ammonia emissions are from agriculture with a significant fraction of that coming from fertilizer. A new bidirectional ammonia flux modeling system has been developed in the Community Multiscale Air Quality (CMAQ) model, which has close linkages with the Environmental Policy Integrated Climate (EPIC) agricultural ecosystem model. Daily inputs from EPIC are used to calculate soil ammonia concentrations that are combined with air concentrations in CMAQ to calculate bidirectional surface flux. The model is evaluated against surface measurements of NH Ammonia is one of many pollutants that are added to the air by human activities. Ammonia contributes to degraded air quality mainly because it adds to the concentration of very fine particles suspended in the air that are called aerosols. Hazy conditions with poor visibility are often the result of high concentrations of aerosols. Also, breathing air with high amounts of aerosols is bad for human health. Ammonia can get into water bodies where it contributes to algae growth and fish kills due to low oxygen. Much of the ammonia that gets into the air comes from fertilizer in agricultural fields. This paper is about improved methods for modeling the ammonia from agricultural fertilizer by linking together an air quality computer model with an agricultural management model. The agricultural model predicts the amount and types of fertilizer that farmers use and the amount of ammonia in the soil. The air quality model then uses information from the agriculture model to predict how much ammonia gets into the air. The study describes these models and shows how well they predict the amount of ammonia in the air compared to ground-based and satellite measurements. While this approach captures spatial variations due to land use, the Γg and Γst values are constant so they do not respond to timing and rate of fertilization. Γst and Γg associated with fertilizer application followed by an exponential decay back to background levels. While this approach adds parameterized dynamics for response to fertilization, it requires additional input for fertilizer application amount, type, and timing.Ammonia bidirectional flux models have recently been applied in several regional and global atmospheric chemistry models. For example, 3 compensation concentration is computed from the total ammoniacal nitrogen pool in the soil. For timing of fertilizer application, the CLM uses the spring planting date for corn from the CLM4.5 internal crop model  since the early 1980s. The system is a comprehensive terrestrial model with key physical and biogeochemical processes simulating plant growth, water and carbon balance, soil erosion, and nutrient cycling  under the influence of soil, landscape, weather, climate, and management conditions  consistent with air quality simulations. As N fertilization varies by type, rate, and timing, depending on production types and geographical area, the agricultural model can resolve soil physical and chemical properties on managed land much more realistically in time and space with different soil and micrometeorology conditions. Simulated soil ammonia concentration along with soil physical properties from the agricultural model can be directly input to bidirectional NH., DSSAT , DNDC  developnditions . The EPInditions .3 flux from managed agricultural soils can be reasonably estimated using a resistance and compensation point flux approach  modeling system  Center (https://www.cmascenter.org/) with the support from U.S. EPA. The released package is developed for Linux system applications and comes with a Java-based interface, an adapted implementation of EPIC for WRF-CMAQ regional grid domain applications, the required data sets, and built-in tools  in two soil layers (1 and 5 cm) according to After an extensive model spin-up period of typically 25 years (100 years for potatoes) using climatological meteorology data, the EPIC model is run for the specific year to be modeled by CMAQ with the same WRF meteorology as used to drive CMAQ on the same spatial grid. FEST-C EPIC also uses CMAQ N deposition input. If WRF-CMAQ is run in two-way coupled mode, then the EPIC model simulation uses a previously run WRF-CMAQ simulation to define the meteorological and N deposition inputs. Daily values of all soil parameters needed to compute the available soil ammonia concentrations for each of 21 agricultural production types that are either rainfed or irrigated  are input to CMAQ. In CMAQ, the ratio of NHue of 20 , for eacχg is in μg/m3, 15) and B  are constants derived from the equilibria constants, and the factor Favail accounts for the fraction of total ammonia in the soil that is available for volatilization. The concentrations of NH4+ and H+ are derived from EPIC inputs for each of 42 agricultural types. The molar concentrations of H+ are specified by each type on an annual basis from pH values with the assumption that there is little daily variation in soil pH for managed agricultural soils. The molar concentrations of NH4+ are computed from daily EPIC estimates of the ammonia pool in the 1- and 5-cm soil layers and the soil moisture content of these layers aswhere 3 is total NH3 in soil layer 1, d1 is soil layer thickness of layer 1 (1 cm), and w1 is soil moisture. The factor Favail in 4+ sorption to soil particles with CEC was also found by where L1_NHSince strong correlation of available fraction with CEC has been shown, we decided to implement a simple parameterization following the EPIC model  as(3)FaFavail is used in the parameterization of volatilization in EPIC and CEC is in cmol/kg. This parameterization results in values for Favail that range from 0.3 to 1. Favail values in soil layer 1 for the 12-km grid resolution CMAQ modeling domain. Clearly, this factor is a significant source of uncertainty in the bidirectional flux model that warrants more study.where 2.3.2.3 concentrations in the soil pore air space or the stomatal cavity in Henry’s law equilibrium with aqueous ammonium ion and hydrogen ion in solution (in the soil water or in the apoplast leaf tissue) computed as Γg values, which are computed from EPIC inputs as described above, and stomatal concentrations are computed from Γst values specified by land use category adapted from Γlitter, but also that the values are highly dynamic and poorly understood . Much of the NH3 flux from the soil is removed by deposition to the leaves both through stomata and the leaf cuticles. 3 emissions in a corn field in mid-July were deposited to the canopy. Estimates of 73% canopy uptake for the same field study derived from in-canopy measurements by Complete description of the bidirectional resistance model is presented by Rw, is parameterized as a function of both relative humidity (RH) and the in-canopy NH3 concentration following laboratory experiments described by The cuticle resistance, Heff is the effective Henry’s law constant that includes effects of aqueous dissociation, χc is the concentration in the canopy (μg/m3), RH is in percent (%), and the empirical constants are Rwo = 125,000 s/m, χref = 1.0 μg/m3, and Rwmin = 20 s/m.where LAI is the leaf area index, Rsoil, is parameterized asSoil resistance is another key resistance for bidirectional ammonia flux because it is a critical regulator of flux from the soil where ammonia is often highly concentrated in the soil water in fertilized agriculture lands. Ldry, the characteristic length scale accounting for tortuosity through the soil surface dry layer, is a function of soil moisture relative to saturation, and Dp, which is the gas diffusivity through the soil pores, is computed from soil characteristics such as porosity, residual moisture content, and the slope of the retention curve. Detailed descriptions of Ldry and Dp are given by where 3.3 flux modeling system are evaluated through comparisons to ambient air concentrations from ground measurements and satellite retrievals, and wet deposition measurements. Evaluation of the FEST-C and EPIC components of the system will be presented in a forthcoming publication.The WRF-CMAQ-EPIC system was run for the entire year of 2016 over the CMAQ CONUS 12-km grid domain. The impacts on air quality of the bidirectional NH3.1.2 level in atmosphere is set to be 404 ppm, which represents the average background concentrations for 2016 estimated from measurements at Mauna Loa, HI (https://www.esrl.noaa.gov/gmd/ccgg/trends/). Consistent with WRF-CMAQ simulations, 2011 National Land Cover Database  equation for water erosion, Hargreaves method for daily evapotranspiration, curve number estimate for infiltration, 4-mm slug flow method for percolation and subsurface flow computation, and Armen Kemanian method for denitrification . The agrse NLCD;  and corrThe WRF model version 3.8.1 was run for the CONUS domain starting on 22 December 2015 and running continuously through 31 December 2016. WRF model physics includes RRTMG shortwave and longwave radiation , Pleim-X3 flux model. The run with the bidirectional model is referred to as the bidi run, while the run without the bidirectional model is referred to as base. The base simulation uses agricultural fertilizer emissions using monthly county level emission factors based on early versions of FEST-C and CMAQ with the bidirectional ammonia flux model as described in CMAQ model version 5.3 was initialized on 22 December 2015 and run continuously through 31 December 2016. The model was configured to use the CB6 gas-phase chemical mechanism and AE7 aerosol model. Anthropogenic emissions were provided from the 2016beta Emissions Modeling Platform . The CMA3.2.4+) depends on the concentrations of anions in the air, typically sulfate, nitrate, and chloride, which can combine with ammonium to form ammonium sulfate ((NH4)2SO4), ammonium bisulfate (NH4HSO4), ammonium nitrate (NH4NO3), and ammonium chloride (NH4Cl). Ideally, an evaluation of ammonia fluxes would include comparisons of model predictions to ambient concentration of NHx that would include both gas and aerosol forms (NHx = NH3 + NH4+). Unfortunately, NHx is not currently measured at national networks in the U.S.. Therefore, evaluation of CMAQ entails a combination of gas, aerosol, and wet deposition measurements. The CMAQ model with the bidirectional NH3 surface flux is evaluated for surface level NH3 concentration through comparison to surface site measurements at the National Atmospheric Deposition Program (NADP) Ammonia Monitoring Network (AMoN) and surface NH3 concentration retrievals from the Cross-Track Infrared Sounder (CrIS) satellite sensor. Wet deposition of NH4+ is evaluated through comparison to the NADP National Trends Network (NTN). Ammonium and sulfate aerosol components are evaluated through comparisons to the Chemical Speciation Network (CSN), the Clean Air Status and Trends Network (CASTNET), and Southeastern Aerosol Research and Characterization  greatly underpredicts NH3 concentrations compared to AMoN, particularly for the warm season , when the monthly median model values are biased low by about 75%. The simulation with the bidirectional fluxes (labeled bidi in subsequent figures and discussion) predicts much greater NH3 concentrations that compare more favorably with the AMoN measurements particularly during the growing season. The median values from the bidi run are within 20% of the observed median values for the warm season (May–September), although the modeled interquartile ranges (length of bars) are smaller than the observations. For winter months, December through March, the bidi model underpredicts at the AMoN sites by an average of 62%. However, since NH3 volatilization is an exponential function of temperature 3 from managed agriculture soils is likely to be a much smaller fraction of total ammonia emissions in the winter than during the growing season, which suggests that other sources of ammonia emission are underestimated by the model.The AMoN measures ambient gas-phase ammonia on a 2-week accumulated average basis at 66 sites across the CONUS . Only th3 concentrations occur in the Central Valley of CA (only one site), the Central Plains as represented by only four sites clustered in southeast Nebraska and northeast Kansas, and the Corn Belt of Illinois, Indiana, Ohio, Wisconsin, and Michigan. Note that the high concentrations in southeastern NC shown in the measurements and model are in an area of concentrated hog facilities.Measured ammonia concentrations averaged over the warm season (May–September) at each AMoN site where at least 75% of the data were valid, and comparable modeled (bidi) concentrations are shown in The scatterplot of measured and modeled concentrations at AMoN sites for May through September  shows co3.4.3 and HNO3 and aerosol-phase ammonium, nitrate, sulfate, calcium, potassium, magnesium, sodium, and chloride. The thermodynamic equilibrium among these species, which depends strongly on temperature and humidity, is computed by the ISORROPIA v2.1  into gas-phase and aerosol-phase ammonia depends on concentrations of the gas-phase NHPIA v2.1 . Note th4+ aerosol components, CSN and CASTNET, in addition to the SEARCH regional network. CSN and SEARCH measure speciated aerosols from 24-hr average filter samples every 3 days and CASTNET uses weekly filter pack measurements. 2.5 NH4+ concentrations averaged over the warm season (May–September). At most CSN sites (other than CA) the model overestimates the reported measured concentrations while the model generally underestimates concentrations at CASTNET and SEARCH sites. At locations where CSN sites are close to CASTNET and SEARCH sites the model bias is often of opposite sign. Part of this discrepancy may be that CSN is designed to represent urban sites, while CASTNET is designed to characterize background rural locations. However, discrepancies between CSN and SEARCH may be more indicative of measurement artifacts. 4+ concentrations, while SEARCH measurements agree well with the thermodynamic models and the SOAS Monitor for AeRosols and Gases in Ambient air (MARGA) measurements. Although 4+ measurements from CASTNet, 4+ are likely more realistic than CSN. Considering the likely greater fidelity of CASTNet and SEARCH than CSN, 4+ .There are two national networks that measure NH4+ on SO42−, comparison to ambient sulfate measurements is also relevant to ammonia model evaluation. 2.5 SO42− concentrations averaged over the warm season (May–September) compared to measured SO42− concentrations from the Interagency Monitoring of PROtected Environments (IMPROVE), CSN, CASTNet, and SEARCH networks. With the exceptions of the northwest and a few sites around the Great Lakes and New England, the model generally underestimates SO42− compared to all four networks. These results suggest that the model’s tendency to underestimate NH4+ may be in part related to underestimation of SO42−. Modeled and measured PM2.5 NH4+ and PM2.5 SO42− concentrations have very similar spatial patterns (not shown) with peak concentrations along the Ohio River where SO2 emissions are greatest.Given the strong dependence of NH3.5.4+ wet deposition in kg/ha per week from the NTN measurements compared to CMAQ. During the summer months (June–September), the CMAQ bidi run agrees well with NTN for both the median values and the 25–75% distributions, while the base is much lower. Observed seasonality, however, is not well replicated by either model simulation. The NTN data show peak wet NH4+ deposition in April and May, while CMAQ results peak in June and July. A possible reason for under prediction of wet deposition in the springtime months could be underprediction of the precipitation. However, The NADP NTN wet deposition network measures precipitation chemistry on an accumulated weekly basis. Since precipitation amount is also measured, chemical wet deposition flux is determined. An advantage of wet deposition measurements is that both gas and aerosol phase NHx should be nearly equally scavenged by precipitation since ammonia gas will be almost entirely dissolved in cloud water , which m4+ wet deposition for the warm season (May–September) are shown in 3 emissions from hog operations are underestimated or the wet scavenging of gas and/or aerosol ammonia is underestimated.Spatial plots of NADP NTN measured and CMAQ bidi modeled NH3.6.3 is obtained from CrIS radiance measurements by applying the CrIS Fast Physical Retrieval (CFPR) algorithm, which provides ammonia volume mixing ratio profiles; the peak sensitivity of the CFPR retrieval is in the boundary layer, typically around 850–750 hPa, but it can be close to the surface under ideal conditions  instruments from the Network for the Detection of Atmospheric Composition Change  retrievals are re-gridded to the CMAQ 12-km grid cells. The CrIS values are presented in 3 concentrations averaged over each month from daily 13:30 values. Note that there is not an exact correspondence between observed and modeled monthly averages because CrIS, due to clouds, does not return valid data every day of the month, although there are usually 20–30 valid observations per grid cell.The Cross-Track Infrared Sounder Satellite (CrIS) instrument is deployed aboard polar orbiting Suomi NPOESS Preparatory Project (SNPP) satellite in a Sun-synchronous orbit with overpass times of ~01:30 and ~13:30 local time. NHnditions . CrIS NHe NDACC; ; CrIS NH3 concentrations do not correspond to the areas with greatest crop and pasture coverage, which indicates that simple schemes that scale emissions by crop area or specify Γg values by land-use categories, are not adequate. Factors such as fertilizer amount and type, soil type, soil moisture, and soil pH are all critical factors that influence NH3 flux.The CrIS monthly average concentration maps reveal far more information on the spatial distribution of ammonia concentrations than can be discerned from the AMoN network. An obvious difference between the CrIS maps and the model maps is in very low concentration conditions, especially in the colder months, where the background color is different. Since the detection limit for the CrIS retrievals is about ~0.5 to 1 ppb , and non3 concentrations from the bidi model compared to the CrIS data show general similarity of spatial distributions with highest concentrations in June and July over the United States. Compared to CrIS, the model underpredicts NH3 concentrations in the spring (March–May) over most of the modeled region but overpredicts in the CA Central Valley all year round. Another significant difference is that modeled NH3 is much greater than CrIS NH3 in Iowa and southeastern NC, which are both hot spots for intensive hog production. This is an opposite result from the NH4+ wet deposition comparisons at NADP NTN sites in these areas, where the model underestimates NH4+ wet deposition . This suggests that net surface fluxes from agricultural soils plus other NH3 emissions may be underestimated. Comparison of monthly averaged concentrations to CrIS retrievals shows that during the warmer months, the modeled NH3 concentrations are less than CrIS in most of the predominantly agricultural regions. However, a few areas stand out where the model concentrations are consistently greater than CrIS over many months. Two areas overpredicted compared to CrIS are the northern half of Iowa into southern Minnesota and southeastern NC, which are the two biggest hog producing areas in the country. The Central Valley of CA is also persistently overpredicted compared to CrIS. Since peak sensitivity in the Central Valley for CrIS retrievals is at about 900–800 hPa, and the PBL mixed layer is often quite shallow, especially in the cooler months, uncertainty at the surface is much greater with substantial high and low biases. The Central Valley includes intensive agricultural production, much of which is irrigated, and other significant sources of ammonia emissions such as animal feeding operations and mobile sources. While analysis of other (nonfertilizer) NH3 emission sources such as from animal feeding operations is beyond the scope of this paper, it is interesting to investigate episodes of high NH3 concentration associated with very large upward surface fluxes from the NH3 bidirectional model.Overall the bidi model seems to underpredict ammonia gas and ammonium aerosol concentrations but to a far lesser degree than the base model. For example, the model shows a low bias in NH3 on June 24 at 20 UTC where positive values indicate upward evasive fluxes and negative values are downward dry deposition fluxes. The white areas indicate either nearly zero flux  or negative (deposition) fluxes. In the colored areas the flux is upward from the surface to the air. While the areas with the greatest upward flux varies day to day depending on meteorology, soil chemistry, crop type, and growth stage, the same areas in the Central Valley of CA, the Snake River Valley in Idaho, and the western High Plains in northern Texas, western Kansas, Eastern Colorado, and South Dakota often stand out with high upward fluxes. The relatively high soil pH in these areas as shown in Γg as shown in Γg is the ratio of ammonium ion to the hydronium ion, one unit difference in pH translates to a factor of 10 difference in Γg.3 concentration on 30 June of 233 ppb occurred at 03 UTC (8 p.m. PDT) in the San Joaquin Valley about halfway between Fresno and Bakersfield. As is typical of most areas in the Central Valley, this particular 12- × 12-km grid cell is mostly agriculture with 65% coverage by crops and 15% coverage by fertilized grasslands. Although there are four dominant crop types and four main grass types, the high value of Γg is mainly the result of irrigated cotton even though it only accounts for 8.8% areal coverage. The reason for the dominance of irrigated cotton in this cell is a combination of high pH (7.75), relatively dry soil (0.08 by volume) and very high amount of ammonia loading in the surface soil layer (29.6 kg/ha). These values result in a calculation for Γg of 15,000,000, which, when weighted by the 8.8% area, contributes 1,300,000 to the grid cell average of 1.9 million. The ammonia loading in this instance is anomalous compared to the other main crop types in this cell which range from 0.26 kg/ha for irrigated other crops to 2.8 for irrigated alfalfa. Other areas with significant coverage by irrigated cotton such as in the Mississippi River Valley do not result in such high Γg values and fluxes even though there are occasionally similar large amounts of soil ammonia because of lower pH and wetter soil conditions.To better understand the very high concentrations in the Central Valley of CA simulated by the CMAQ bidi compared to CrIS –14, we i3 concentration of 214 ppb. While the largest crop fraction in this cell is classified as irrigated other crops (38%), which is mostly almond groves, the NH3 fluxes are dominated by extremely high Γg values for irrigated corn silage, which only accounts for 12% of the area. Again, the main reason for the high calculation of Γg is the anomalously high soil ammonia loading from FEST-C EPIC (28.3 kg/ha). Thus, it is not a single crop type responsible for the episodes of very high fluxes that result in extreme NH3 concentrations in the Central Valley but rather sporadic unrealistically high soil ammonia loading for different crop types. The application of the EPIC model, which was designed as a field scale model, to the gridded domain over the entire CONUS requires regional and county level parameterizations and soil data  the model simulated NHoil data . Further5.The new implementation of ammonia bidirectional surface flux in the WRF-CMAQ modeling system is closely linked with the EPIC agricultural model through the FEST-C interface. The daily EPIC model simulated parameters including soil ammonia content, soil pH, soil moisture, and other soil characteristics  are critical for calculating the soil emission potential, which defines the soil compensation concentration that is the primary source for the surface-to-air flux. EPIC is a comprehensive process-based agro-ecosystem model that has been successfully used worldwide e.g., . The modThe key components of the ammonia bidirectional flux model include the various resistance parameters that define the flux pathways to and from the soil and plant stomata and cuticle through the canopy. Many of these resistances are inherited from the dry deposition model in CMAQ M3DRY; ; some of3 fluxes over the CONUS domain are not available, evaluation of the model must be inferred from measurements of ambient concentrations of gas and aerosol concentrations and wet deposition. The combined analysis shows that the CMAQ bidi model well represents all three forms of ammonia with a relatively small negative bias. Given the uncertainties in many model parameters, these biases could easily switch to overestimation or larger underestimation with small adjustments to a few key parameters. Future research could investigate parameter sensitivities through combined parameter uncertainty experiments like sensitivities studies performed for PBL models  with improved land use, soil, and management representations at finer scales such errors will likely be reduced.Analysis of the 2016 WRF-CMAQ-EPIC simulations reveals some issues that cause unrealistically high fluxes and NH


DBP5 lead to stop codon readthrough, because the eRF1 and eRF3 interaction is not controlled and occurs prematurely. This identifies Dbp5/DDX19 as a possible potent drug target for nonsense suppression therapy. Neurodegenerative diseases and cancer are caused in many cases by the loss of a gene product, because its mRNA contained a premature termination codon (PTC) and is thus eliminated through the nonsense mediated decay (NMD) pathway, which is described in the second half of this review. We discuss translation termination and NMD in the light of Dbp5/DDX19 and subsequently speculate on reducing Dbp5/DDX19 activity to allow readthrough of the PTC and production of a full-length protein to detract the RNA from NMD as a possible treatment for diseases.The DEAD-box protein Dbp5 (human DDX19) remodels RNA-protein complexes. Dbp5 functions in ribonucleoprotein export and translation termination. Termination occurs, when the ribosome has reached a stop codon through the Dbp5 mediated delivery of the eukaryotic termination factor eRF1. eRF1 contacts eRF3 upon dissociation of Dbp5, resulting in polypeptide chain release and subsequent ribosomal subunit splitting. Mutations in  Translational control is an organized and adaptable mechanism, which is vital for all organisms in life. The expression level and the quality of the protein expressed from a protein-coding gene depend both on the stability and on the quality of the expressed mRNA. Eukaryotic cells have evolved nuclear and cytoplasmic mRNA surveillance systems. Nuclear quality control captures transcripts that experience problems in 5′-capping, 3′ polyadenylation and/or intron splicing, prevents their nuclear export and initiates their degradation ,2,3. In In this review we will summarize the process of translation termination with a focus on Dbp5/DDX19. We will then introduce the principles of NMD and explain the role of Dbp5/DDX19 between these two events. Finally, we will discuss why we think that Dbp5/DDX19 might be an interesting drug target to manipulate these processes and use this for potential treatments of diseases.SUP45 in yeast) binds to the ribosomal A-site. eRF1 interacts with the GTPase eRF3 (encoded by SUP35 in yeast), leading to polypeptide chain release and ribosome recycling 16]. Althfor Dbp5 ,46.DBP5, in which eRF1 does not bind and is therefore not delivered to the ribosome by the helicase. The scenario at the ribosome after Dbp5 has delivered eRF1 and has left the termination complex continues with the interaction of eRF1 and eRF3 . Their iWhen Dbp5 is not functional, as shown in several mutants, eRF1 approaches the ribosome on its own and contacts eRF3 before it is properly positioned for termination, resulting in the immediate dissociation of both release factors and translational readthrough . InefficIn most cases, general readthrough might be problematic for cells, however, tuning readthrough also holds the possibility for regulation. Such a potential regulation is still unclear and not much is known for a possible role of Dbp5. However, for example during stress, Dbp5 localizes to the nuclei of cells  and is tFor more than 25 years, one major goal has been to understand the mechanisms underlying NMD. Although at first only considered as a cytoplasmic mRNA quality control system, current research has clearly identified its power in regulating the RNA-transcriptome beyond RNA surveillance, e.g., in biological contexts such as development ,50. TherS. cerevisiae phosphorylation of Upf1 was also described, but there the relevance is not clear [Generally, in mRNA surveillance, a premature termination codon (PTC) is distinguished from a normal one as the trigger for NMD. NMD can only be initiated during translation termination as it requires the decoding of a stop codon by eRF1 and eRF3 . At a PTot clear ,64. AfteOf course, the NMD pathway should only be initiated when translation termination occurs prematurely. Several models have been proposed to describe the differentiation of a normal stop codon and a PTC. The two main models are the exon junction complex (EJC) induced NMD and the long 3′UTR model . The forAlthough there is growing insight into the mechanisms by which NMD is initiated and degrades transcripts, there are still many open questions. It is for instance unknown how PTC-detection is signaled to the ends of the transcript, where degradation is initiated. In this context, the mRNP conformation during NMD is presumably important but not yet understood. For the EJC induced NMD in humans, it was described that Upf1 interacts with the cap binding complex (CBC) in a process where the mRNA might fold back so that the Upf1 complex at the PTC can reach the 5′ end ,81. In yIn the EJC independent initiation of NMD, it is unclear how Upf2 and Upf3 join Upf1. In yeast, it is assumed that they must be specifically recruited to NMD targets, due to their low cellular abundance. However, their association with translated mRNPs is Upf1 independent , suggestNMD of different targets presumably requires a different subset of proteins; even the co-factor Upf2 is not required for all NMD ,67. WhicAnother aspect is important in this regard. Many inherited human diseases and cancer types are caused by the loss of a specific protein due to the elimination of its transcripts that contained a premature termination codon (PTC) ,86,87. IIt was observed that overexpressing Upf1 alleviates the negative effects in a TDP-43 induced rat model of the neurodegenerative disease ALS . Thus, pAttempts were started to downregulate NMD, allowing the production of some of the full-length protein as treatment for diseases. Such drugs could act as nonsense suppressors . These compounds can be natural or synthetic aminoglycosides and nonaminoglycosides ,105,106.Further, different NMD targets do not respond similarly to one nonsense suppressor. Ataluren , a therapeutic for Duchenne muscular dystrophy, was not approved for Cystic Fibrosis, as clinical trials did not show sufficient improvement ,109. ThiStrategies to repress NMD for correct protein production are one hope for therapy. Understanding the full mechanistic details of translation termination and NMD in the cellular context will be important and necessary to develop more sophisticated therapies for PTC-caused diseases.


Triple-negative breast(TNBC) cancer is a molecular subtype of breast cancer with poor prognosis and did not get approved targeted therapy till now. In the last years, metronomic chemotherapy (mCTH) was investigated to improve treatment outcomes in TNBC patients both in early and metastatic setting due to its anti-angiogenic and immune-stimulatory mechanisms. The aim of this study is to evaluate the efficacy and safety of extended adjuvant chemotherapy with metronomic docetaxel for patients with operable TNBC. 2 in weekly bases for 4 weeks then the dose was escalated to 20 mg/m2 once per week if there were no side effects. 31 women with clinically and pathologically proved operable TNBC, either node-negative or node-positive with tumor size ≥ 0,5 cm were enrolled after finishing the primary standard of care treatment. The patients were subjected to extended adjuvant therapy for 6 months with metronomic low dose docetaxel with starting dose of 15mg/mAfter a median follow up of 36 months (range 6-52), 24 patients (77.4%) were still alive. During the period of follow-up, 12 patients (38.7%) showed disease relapse and 19(61.3%) cases remain free of the disease. The estimated mean of DFS in our study was 38.26 months  with 2 and 3 years DFS rate of 70.5 % and 56.4% respectively while the estimated mean of OS was 43.75 months  with 2 and 3 years OS rates 83.3% and 78.1% respectively, Generally the treatment was tolerated with mild to moderate hematological and non hematological adverse events, all are grade 1,2 and treatment-related deaths were not observed. Extended adjuvant treatment for 6 months with metronomic docetaxel after the primary standard of care therapy was tolerated and has an encouraging survival benefit in patients with operable TNBC and these results need further evaluation in randomized control studies. Generally, breast cancer (BC) is a highly heterogeneous disease at both clinical and molecular settings, Triple-negative breast cancer (TNBC) accounts for around 20% of the all BC molecular subtypes and has a very worse prognosis with short overall survival . After the primary treatment of TNBC, the median time for tumor relapse is approximately 18-20 months with subsequent less than 2 years overall survival after relapse . In comparison to other BC subtypes, TNBC cases are prone to develop visceral metastases more common than bone metastases and occur in younger age groups. Although there is a relative value of chemotherapy in these cases and a large number of clinical studies, no optimal neo/adjuvant chemotherapy regimen has been identified . A novel approach to improve disease-free survival and subsequent overall survival of TNBC patients is the use of extended adjuvant treatment with metronomic chemotherapy (mCTH). In (mCTH), the chemotherapeutic drug can cause modulation in the cancer cell microenvironment and disruption of the tumor angiogenesis, this could be achieved by administering chemotherapeutic agent in low doses on weekly or even daily bases without a prolonged interval . Various preclinical and clinical studies have shown metronomic chemotherapy might show alternative anti-neoplastic effects of the drugs in addition to its direct cytotoxic effect . The main objective of mCTH is to achieve a comparable or good efficacy along with tolerability and safety compared to standard conventional chemotherapy, Also, it is considered by some authors as an attractive novel approaches with additional anti-angiogenic effects with lesser toxicities compared to the standard chemotherapy . In TNBC, there are many clinical trials investigating the role of extended adjuvant therapy with metronomic chemotherapy after the primary standard treatment . In the preclinical setting, Di Desidero and colleagues investigated the potential effect of combination of metronomic low dose of topotecan with pazopanib in primary or metastatic triple-negative breast cancer cell lines, and their conclusion was that combination needs further evaluation being a potential therapeutic option for that type of breast cancer . In clinical studies, there are many studies investigated the role of mCTH in patients with non-metastatic TNBC and will be mentioned in the discussion section . Docetaxel has been recognized both in vivo and in vitro studies as an active agent that can exhibit a metronomic activitiy . The efficacy of taxanes both neoadjuvant and adjuvant settings in TNBC was established and still part of the standard of care in the management of this aggressive subtype of breast cancer. Therefore, we hypothesized that patients with TNBC might achieve a survival benefit from mCTH with docetaxel. In this study, we evaluated the efficacy and toxicity of a novel metronomic extended adjuvant regimen in patients with early TNBC. As far as the authors know, this is the first study of a true weekly metronomic regimen with docetaxel in TNBC.Patients EligibilityThis study was conducted at the department of clinical oncology and nuclear medicine, Zagazig university hospitals from April 2015 to February 2018 where 31 women with clinically and pathologically proved operable triple-negative breast cancer, either node-negative or node-positive with tumor size≥0.5cm were eligible for entry of this study, all patients were followed till August 2019. Other inclusion criteria are: age 18-70 years, adequate bone marrow and organ functions, and ECOG performance status (PS) 1-2. Patient was excluded if there is distant metastasis or other active malignancy in the body elsewhere, previous docetaxel in the primary adjuvant treatment, other, also, patient who did not wish to continue on the treatment plan had permission to be excluded. Informed written consent from all patients.Study design and Ttreatment plan2 in weekly bases for 4 weeks then the dose was escalated to 20 mg/m2 once per week if there was no neutropenia. Before docetaxel administration, antiemetic, H1-blocker, and 4mg dexamethasone were given as a pre-medications to prevent vomiting and hypersensitivity reaction, then docetaxel administrated as an intravenous infusion in 250 ml dextrose 5% over 60 minutes. The treatment was continued for 6 months if there was intractable toxicity or development of local or distant metastasis.This is a prospective, single-institution, phase II single-arm study. The protocol of the study was approved by the ethical committee in the department of clinical oncology. The patients met above inclusion criteria and had received standard adjuvant treatment either anthracycline or taxane based chemotherapy with adjuvant radiotherapy if indicated were subjected to extended adjuvant therapy with metronomic low dose docetaxel with starting dose of 15mg/mPatients assessment and Treatment follow-upDuring the treatment, patients were monitored weekly by general and laboratory examinations for bone marrow and organ function reserves to confirm the tolerability of the treatment. Detection of disease progression was monitored every 3 months during and after the treatment by general physical examination, chest x-ray, abdominopelvic ultrasound, and mammography. Computed tomography (CT) was ordered if there were any suspicious lesions in ultrasound or x-ray, isotopic bone scan ordered only if there were symptoms suggestive of bone metastasis or increased serum alkaline phosphatase, otherwise annually. Treatment-related adverse effects were graded according to the common terminology criteria of adverse events (NCI-CTC v3).EndpointsThe primary endpoints of this study were treatment tolerability and disease-free survival while the secondary endpoint was overall survival.Statistical analysisAll statistics were performed using SPSS 22.0 for windows  and MedCalc windows . Disease-Free Survival (DFS) was calculated as the time from date of surgery to date of 1st disease relapse or the most recent follow-up that patient was known as free from the disease while Overall Survival (OS) was calculated as the time from diagnosis of the disease to the death of the patient or for the most recent follow-up (censored).Basic characteristics 31 patients with clinically and histologically confirmed operable triple-negative breast cancer were enrolled in this research. Treatment outcomeTreatment outcome of extended adjuvant treatment with docetaxel for 31 patients with operable triple-negative breast cancer was shown in Regarding the treatment-related toxicities, generally the treatment was tolerated with mild to moderate hematological side effects but there are non-hematological adverse events, all are grade 1, 2 and treatment-related deaths were not observed. Grade 1, 2 anemia is the most common hematological toxicity while pleural effusion is the most frequent non-hematological side effects, Grade 3 neutropenia observed only in 3 (1%) while Grade 3, 4 anemia was observed in 8 (25%) and 2 (0.6%) respectively. For both hematological and non hematological toxicities no dose reduction or interruption required and all side effects were easily manageable. Summary of all treatment-related adverse effects are presented in DiscussionTNBC is a heterogeneous subtype of breast cancer characterized by several molecular variants differed in their natural history and may need different options of treatment. Till now, taxanes and anthracyclines-based therapy is the standard of care regimens if chemotherapy is indicated . Compared to hormone receptor-positive breast cancer, the duration of adjuvant treatment in TNBC is still an unanswered question, therefore, there are several studies investigating different regimens with different treatment duration .In the last decade, mCTH showed a promising activity through its anti-angiogenic and immune-stimulatory mechanisms and so, researchers considered TNBC as a very good candidate for this novel regimen  . To improve the treatment outcome in TNBC, the researchers tried to investigate the role of extended adjuvant therapy after the primary standard chemotherapy . Several drugs were investigated in this era of research in both phase II and phase III trials, capecitabine was one of the most investigated drugs in maintenance therapy in TNBC. The largest phase III trials that investigated the extended adjuvant mCTH in TNBC are CIBOMA 2004-01/GEICAM 2003-11 and SYSCBS-001 trials. In CIBOMA trial, the efficacy and safety of maintenance therapy of capecitabine were evaluated after primary treatment in patients with early stages TNBC , while in SYSCBS-001, capecitabine was evaluated as in CIBOMA studies but with different dose and duration Zhong-yu., NCT01112826). Also, the efficacy of extended therapy with capecitabine was evaluated in a famous phase III trial, the CREATE-X trial that showed a significant improvement in survival in patients with TNBC with a residual disease after neoadjuvant therapy . Docetaxel exhibit significant activity in management of TNBC in both neoadjuvant and adjuvant settings either alone or in combination with other drugs . In this study, extended adjuvant treatment with a metronomic low dose of docetaxel was used for patients with operable TNBC after the primary standard adjuvant therapy. To our Knowledge, this is the first study that evaluated the safety and efficacy of extended adjuvant chemotherapy with metronomic docetaxel in TNBC. Our hypothesis based on the results of the studies that demonstrated good efficacy and tolerability of metronomic docetaxel in other solid tumors. In lung cancer, Yokoi et al underwent a pilot study to evaluate the toxicity and efficacy of low-dose docetaxel for patient with previously treated non-small cell lung and their conclusion that metronomic regimen was well tolerated and active, but they recommended further investigations . In breast cancer, Young et al investigated the role of metronomic docetaxel combined with capecitabine in patients with metastatic breast cancer and they concluded that metronomic docetaxel combined with capecitabine chemotherapy can produce a significant anticancer effect, with predictable toxicity . The preliminary results of our study demonstrated encouraging effects with acceptable toxicities, the estimated mean of DFS in our study was 38.26 months  with 2 and 3 years DFS rate 70.5 % and 56.4% respectively but the median rate was not reached and the estimated mean of OS was 43.75 months  with 2 and 3 years OS rates 83.3% and 78.1% respectively, the median OS was not reached also.2, twice every day) for one year after finishing the standard adjuvant treatment , in their results, the mean DFS was 41.7 months  and The 2 and 3 years DFS rates were 88.8% and 82.05%, respectively, that was at some extent the same as that obtained in our study, although the median follow-up period and number of patients is less than that in our research. Also, Alagizy et al underwent another study as that of Shawky study for the same purpose but with different dose and duration schedule, they used 6 mounhs of metronomic capecitabine 500 mg two times by per-day after recieving 6 cycles of adjuvant chemotherapy with FEC100 with or without adjuvant radiotherapy, the mean DFS and mean OS were was 42.4 months  and 44.34 months (95% CI 41.9–46.9) respectively, while both median DFS and OS were not reached, and their conclusion that metronomictherapy with low dose capecitabine was safe and the results need to be compared with control arm in the future studies . Compared to the obtained results of other studies conducted in our country that evaluated the extended adjuvant therapy in TNBC, Nasr and colleagues investigated the safety and efficac of metronomic methotrexate and Cyclophosphamide given for 1 year after the standard adjuvant therapy for cases with TNBC in an attempt to improve the disease-free survival of such patients , the median DFS and OS in their results were 28 and 37 months respectively that appeared less than that obtained in our study and his conclusion was that metronomic therapy was well tolerated and achieved significant improvement in both DFS and OS. In another study conducted by Shawky and Galal, 19 patients with operable TNBC were subjected to receive metronomic capecitabine therapy  where 724 patients with TNBC were subjected to receive metronomic cyclophosphamide 50 mg/day orally and oral methotrexate 2.5 mg/twice days 1 and 2 weekly for 1 year or placebo after finishing the standard adjuvant chemotherapy, they found no significant reduction of DFS in maintenance therapy in the general group, however, they noticed that cases with TNBC with node-positive had better 5 year DFS rate in maintenance group (72.5%) than that non-maintenance group (64.6%)  . As a part of (IBCSG 22-00) trial also, Pruneri et al found that patients with so-called lymphocyte-predominant TNBC showed a greeter even statistically insignificant benefit from metronomic schedule . The last update of CIBOMA trial presented in the ASCO post by DR Martin about the role of adjuvant capecitabine in TNBCi n the phase III CIBOMA/GEICAM trial, he showed that, in the overall study population, extending adjuvant capecitabine did not improve survival but in a subgroup of non–basal-like TNBC, extending capecitabine treatment demonstrated improvement in both disease-free and overall survival and he suggest that more in-depth characterization of TNBC might help in treatment selection and he said that their study not finished and they will plan to look at the genomic characteristics of disease to identify which molecular subgroups will benefit from the addition of capecitabine . Unfortunately, the data of the survival results of SYSCBS-001 trial not published till now.Data from previous studies supported the use of extended adjuvant treatment in TNBC specially the metronomic schedule, although capecitabine was heavily investigated in this researches, its efficacy not truly determined to has a survival benefit. Our results compared to the results of the previous studies showed promising efficacy, however, there were some limitations in our study, the most important one was small sample size and there was no control arm, also, the study lacked the cases subjected to neo-adjuvant therapy. Regarding the tolerability, metronomic docetaxel with the dosing schedule used in our study was tolerable and compliant for patients, however, there is no adequate data in the literature regarding the treatment-related adverse effects of this regimen to be compared with our results.Summary and RecommendationIn the last years, efforts had been done to improve the treatment outcome in TNBC due to the lack of targeted therapy. One of the explored methods is using extended adjuvant chemotherapy especially with mCTH after finishing the primary standard of care treatment. We used in our study a novel approach of metronomic docetaxel as an extended adjuvant approach after the standard adjuvant treatment for patients with early TNBC. The results of our study showed that, extended adjuvant treatment with metronomic docetaxel for patients with operable TNBC has a survival benefits with acceptable treatment-related adverse effects. However, due to the small sample size and lack of control arm, further researches are needed to detect the actual benefit from this novel regimen and this need multicentre randomized control studies with a large number sample size.