Retrospective studies in scleroderma: Effect of potassium para-aminobenzoate on survival

Demographic and survival data are presented for 390 patients with scleroderma. For the entire group An estimated, 81.4% survived 5 years from diagnosis and 69.4% survived 10 years. Life-table analyses revealed that adequate treatment with potassium para-aminobenzoate (Potaba(R) KPAB) was associated with improved survival (p per se as a prognostic indicator: the greater the extent of skin involvement the poorer prognosis. Time from first diagnosis to first University Hospital visit or admission when included as a covariate did not influence survival.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27502/1/0000546.pd

Large emissions from floodplain trees close the Amazon methane budget

Wetlands are the largest global source of atmospheric methane (CH4), a potent greenhouse gas. However, methane emission inventories from the Amazon floodplain, the largest natural geographic source of CH4 in the tropics, consistently underestimate the atmospheric burden of CH4 determined via remote sensing and inversion modelling, pointing to a major gap in our understanding of the contribution of these ecosystems to CH4 emissions. Here we report CH4 fluxes from the stems of 2,357 individual Amazonian floodplain trees from 13 locations across the central Amazon basin. We find that escape of soil gas through wetland trees is the dominant source of regional CH4 emissions. Methane fluxes from Amazon tree stems were up to 200 times larger than emissions reported for temperate wet forests6 and tropical peat swamp forests, representing the largest non-ebullitive wetland fluxes observed. Emissions from trees had an average stable carbon isotope value (δ13C) of −66.2 ± 6.4 per mil, consistent with a soil biogenic origin. We estimate that floodplain trees emit 15.1 ± 1.8 to 21.2 ± 2.5 teragrams of CH4 a year, in addition to the 20.5 ± 5.3 teragrams a year emitted regionally from other sources. Furthermore, we provide a ‘top-down’ regional estimate of CH4 emissions of 42.7 ± 5.6 teragrams of CH4 a year for the Amazon basin, based on regular vertical lower-troposphere CH4 profiles covering the period 2010–2013. We find close agreement between our ‘top-down’ and combined ‘bottom-up’ estimates, indicating that large CH4 emissions from trees adapted to permanent or seasonal inundation can account for the emission source that is required to close the Amazon CH4 budget. Our findings demonstrate the importance of tree stem surfaces in mediating approximately half of all wetland CH4 emissions in the Amazon floodplain, a region that represents up to one-third of the global wetland CH4 source when trees are combined with other emission sources

Sampling From The Risk Set In A Cox Survival Analysis: A Large Sample Study (martingales, Estimator, Counting Processes).

The survival times of n individuals (tau)(,1), ...,(tau)(,n) are assumed to be independent with unknown distributions. Associated with each is a time dependent covariate z(,t), which is observed on time t, t (ELEM) 0,(tau)(,i) . For modeling the stochastic relationship between survival time and the covariate, Cox suggested the proportional hazards model, (lamda)(t;z(,t)) = (lamda)(,o)(t)exp((beta)(,o)z(,t)), t (GREATERTHEQ) 0, where (lamda)(,o)(t) and (beta)(,o) are parameters. This dissertation investigates a method for estimating (beta)(,o) based on right censored data, (tau)(,1), ...,(tau)(,n), which are either survival times or lower bounds for the survival times. Associated with them are vari- ables (delta)(,1), ...,(delta)(,n),(delta)(,i) = 0 if (tau)(,i) is a censor time ((tau)(,i) < (tau)(,i)), and (delta)(,i) = 1 if (tau)(,i) is a survival time ((tau)(,i) = (tau)(,i)). A method for estimating (beta)(,o) based on censored data was sugges- ted by Cox. At a survival time (tau)(,i) ((delta)(,i) = 1), the observed event is the death of individual i from among those at risk, R((tau)(,i)) = j: (tau)(,j) (GREATERTHEQ) (tau)(,i) . Using the Cox hazard, (DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI) is the probability of such an event. The product of such factors over all survival times gives the Cox likelihood, and the value (beta)(,C) which maximizes it is the Cox regression estimate. In contrast, Thomas suggested that inference on (beta)(,o) be based on the function (DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI) where K((tau)(,i)) is a random sample of fixed size from the set R((tau)(,i))/(i). In comparison to the Cox likelihood, the denominator of the terms of L(,T) contains the case i and a random sample of the risk set at (tau)(,i), instead of the entire risk set. The argument for L(,T) to be considered as a likelihood is similar to that given by Cox. The value (beta)(,T) which maximizes L(,T) estimates (beta)(,o). In this thesis, an investigation is made of the large sample proper- ties of (beta)(,T). It is assumed that followup takes place during some fixed time interval and that the number of deaths increases, (DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI) It is not assumed that the size of the sampled risk set increases. Con- ditions are given which assure the weak consistency and asymptotic normality of (beta)(,T). The efficiency of (beta)(,T) relative to (beta)(,C) is investigated at the null hypothesis value (beta)(,o) = 0. The approach we take is an exten- sion of that taken by Naes and Andersen & Gill, namely modeling the survival experience of individual i as a counting process with intensity based on (lamda)(t;z(,t)('i)), t (GREATERTHEQ) 0. This approach relies heavily on basic martingale theory and U-statistic theory.Ph.D.Biological SciencesBiostatisticsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/127904/2/8621273.pd

Psychological distress reported by healthcare workers in Saudi Arabia during the COVID-19 pandemic: A cross-sectional study

INTRODUCTION: Few studies have considered the impact of COVID-19 on the mental health of healthcare workers (HCWs) in the Kingdom of Saudi Arabia (KSA). We estimated the prevalence and severity of psychological distress and characterized predisposing risk factors among HCWs in KSA during the COVID-19 pandemic. METHODS: We conducted a cross-sectional online survey of 1,985 HCWs from 6 hospitals across the country designated with caring for COVID-19 patients between April 16 and June 21, 2020. Our data analysis was performed using logistic regressions. Ordered logistic regressions were also performed using forward stepwise model selection to explore the effects of risk factors on psychological distress. RESULTS: The prevalence of psychological distress reported by HCWs in KSA was high, ranging from mild-moderate to severe in severity. Younger HCWs, women, those in contact with COVID-19 patients, and those who either had loved ones affected or who were themselves affected by COVID-19 were the most at-risk of psychological distress. Risk factors such as insomnia, loneliness, fear of transmission, and separation from loved ones most significantly predicted elevated levels of distress among HCWs. CONCLUSIONS: Increasing psychological distress was commonly reported by HCWs during the early months of COVID-19 pandemic in KSA. Public health policy makers and mental health professionals must give special attention to risk factors that predispose HCWs in KSA to psychological distress

Trees are major conduits for methane egress from tropical forested wetlands

Wetlands are the largest source of methane to the atmosphere, with tropical wetlands comprising the most significant global wetland source component. The stems of some wetlandadapted tree species are known to facilitate egress of methane from anoxic soil, but current ground-based flux chamber methods for determining methane inventories in forested wetlands neglect this emission pathway, and consequently, the contribution of tree-mediated emissions to total ecosystem methane flux remains unknown. In this study, we quantify in situ methane emissions from tree stems, peatland surfaces (ponded hollows and hummocks) and root-aerating pneumatophores in a tropical forested peatland in Southeast Asia. We show that tree stems emit substantially more methane than peat surfaces, accounting for 62–87% of total ecosystem methane flux. Tree stem flux strength was controlled by the stem diameter, wood specific density and the amount of methane dissolved in pore water. Our findings highlight the need to integrate this emission pathway in both field studies and models if wetland methane fluxes are to be characterized accurately in global methane budgets, and the discrepancies that exist between field-based flux inventories and top-down estimates of methane emissions from tropical areas are to be reconciled

Epidemiology and Clinical Characteristics of People with Confirmed SARS-CoV-2 Infection during the Early COVID-19 Pandemic in Saudi Arabia

This study provides epidemiologic and clinical characteristics of 492 consecutive patients diagnosed with SARS-CoV-2 infection at King Faisal Specialist Hospital and Research Centre in Saudi Arabia between March and September 2020. Data were collected from electronic case reports. The cohort was 54% male, with 20.4% aged >60 years, 19.9% aged 31–40 years, and 17% aged 41–50 years. The median incubation period was 16 days, with upper and lower 95% quartiles of 27 and 10 days, respectively. Most patients (79.2%) were symptomatic. Variables significantly different between symptomatic and asymptomatic patients were age, blood oxygen saturation percentage, hemoglobin level, lymphocyte count, neutrophil to lymphocyte (NTL) ratio, and alanine aminotransferase (ALT) and aspartate aminotransferase (AST) level. Asymptomatic patients were mostly younger, with lower body mass index and ALT and AST levels but higher lymphocyte counts, NTL ratio, and CD4, CD8, natural killer cell, IgG, and IgM levels. Factors associated with increased risk of mortality were age (>42 years) and comorbidities, particularly diabetes mellitus and hypertension. Patients who were not given an antiviral regimen were associated with better prognosis than patients who received an antiviral regimen (HR, 0.07; 95% CI, 0.011–0.25). These findings will help clinicians and policymakers adopt best management and treatment options for SARS-CoV-2 infection