Pandemics are catalysts of scientific novelty: Evidence from COVID-19.

Scientific novelty drives the efforts to invent new vaccines and solutions during the pandemic. First-time collaboration and international collaboration are two pivotal channels to expand teams' search activities for a broader scope of resources required to address the global challenge, which might facilitate the generation of novel ideas. Our analysis of 98,981 coronavirus papers suggests that scientific novelty measured by the BioBERT model that is pretrained on 29 million PubMed articles, and first-time collaboration increased after the outbreak of COVID-19, and international collaboration witnessed a sudden decrease. During COVID-19, papers with more first-time collaboration were found to be more novel and international collaboration did not hamper novelty as it had done in the normal periods. The findings suggest the necessity of reaching out for distant resources and the importance of maintaining a collaborative scientific community beyond nationalism during a pandemic.

From Child-Pugh to MELD score and beyond: Taking a walk down memory lane.

The Child-Turcotte-Pugh (CTP) and the MELD (Model for End-Stage Liver Disease) scores were designed to predict the outcome of decompressive therapy for portal hypertension. They were prospectively validated to predict mortality risk in patients with a wide spectrum of liver disease etiology and severity. Unlike the CTP score, the MELD score was derived from prospectively gathered data. Its calculation was based on serum bilirubin, serum creatinine, international normalized ratio (INR) and etiology of liver disease. Instituting a continuous disease severity score that de-emphasizes waiting time resulted in better categorization of waiting patients and enhanced transparency. The US instituted the MELD system in 2002 and soon thereafter, MELD-based liver allocation was adopted throughout the world including Latin America. The most significant impact of MELD-based policies has been the reduction of waiting-list mortality. In the years after implementation of the MELD system, several options have been proposed to improve the MELD score's accuracy. Adding serum sodium (MELD-Na) increased the accuracy of the score in predicting waiting list mortality, thus completing the original MELD score as a prognostic model in liver allocation. On the 20th anniversary of the creation of MELD score we present a brief account of its development, its use to stratify patients on the waiting list for liver transplantation as well as its adoption as liver allocation system .

The impact of air filtration units on primary school students' indoor exposure to particulate matter in China.

The air quality in classrooms is a critical factor that affects students' daily exposure. Although air filtration units (AFUs) are often used to reduce exposure to air pollution in China, the effectiveness of installing AFUs in Chinese classrooms have not been quantitatively studied. Hence, we carried out concurrent air quality experiments in two identical classrooms where one room was equipped with commercial AFUs and the other one relied on the natural introduction of outside air. Measurements were taken during regular school days in the winter at a primary school in Hangzhou, China. Three AFU ventilation modes, i.e., fresh air, mixed air and recirculation mode were evaluated, respectively. We found that classrooms equipped with AFU showed significant PM2.5 reductions, but this was accompanied by CO2 build-ups. In classroom with AFUs on internal recirculation, nearly 70% of the PM2.5 concentration at the beginning of the class was reduced by the end of a 40-min class. However, the CO2 concentration was observed to reach levels that were six times greater than that of the ambient due to inadequate air change rate (<1 h-1). To mitigate the issue of excessive in-classroom CO2 accumulation when using AFUs, filtered outside air must be brought in during their operation. In comparison with the internal recirculation mode, we demonstrated that the fresh air mode that draws the supply air from outdoor can considerably lower CO2 build-ups in the classroom with a moderate increase in PM2.5 concentration of 15 ± 10 µg/m3. The findings from this study helps policy makers especially in developing countries with serious air pollution issues to determine whether or not to install AFU in primary schools and what ventilation mode is effective in reducing negative health effects.

Making a national donor research program a reality: Concepts for operationalizing a system.

Deceased donor research remains an elusive goal for improving organ utilization and function. Many working in this field have cited the barriers that impede the conduct of such trials. Recent reports from the Academy of Medicine and individual authors provide a general framework on which a National Donor Research Program could be built. This paper provides one observer's viewpoint on how such a program could be operationalized.

Share capitalism and worker wellbeing.

We show that worker wellbeing is determined not only by the amount of compensation workers receive but also by how compensation is determined. While previous theoretical and empirical work has often been preoccupied with individual performance-related pay, we find that the receipt of a range of group-performance schemes (profit shares, group bonuses and share ownership) is associated with higher job satisfaction. This holds conditional on wage levels, so that pay methods are associated with greater job satisfaction in addition to that coming from higher wages. We use a variety of methods to control for unobserved individual and job-specific characteristics. We suggest that half of the share-capitalism effect is accounted for by employees reciprocating for the "gift"; we also show that share capitalism helps dampen the negative wellbeing effects of what we typically think of as "bad" aspects of job quality.

Characteristics and outcomes of neutropenia after orthotopic liver transplantation.

Neutropenia after orthotopic liver transplantation (LT) is relatively common, but the factors associated with its development remain elusive. We assessed possible predictors of neutropenia (absolute neutrophil count [ANC] ≤ 1000/mm(3) ) within the first year of LT in a cohort of 304 patients at a tertiary medical center between 1999 and 2009 using time-dependent survival analysis to identify risk factors for neutropenia. In addition, we analyzed neutropenia as a predictor of the clinical outcomes of death, bloodstream infection (BSI), invasive fungal infection, cytomegalovirus (CMV) disease, and graft rejection within the first year of LT. Of the 304 LT recipients, 73 (24%) developed neutropenia, 5 (7%) of whom had grade 4 neutropenia (ANC < 500/mm(3) ). The following were independent predictors for neutropenia: Child-Turcotte-Pugh score (hazard ratio [HR] 1.15; 95% confidence interval [CI], 1.03-1.30; P = 0.02), BSI (HR, 2.89; 95% CI, 1.63-5.11; P < 0.001), CMV disease (HR, 4.28; 95% CI, 1.55-11.81; P = 0.005), baseline tacrolimus trough level (HR, 1.02; 95% CI, 1.01-1.03; P = 0.007), and later era LT (2004-2009 versus 1999-2003; HR, 2.28; 95% CI, 1.43-3.65; P < 0.001). Moreover, neutropenia was found to be an independent predictor for mortality within the first year of LT (HR, 3.76; 95% CI, 1.84-7.68; P < 0.001). In conclusion, our data suggest that neutropenia within a year after LT is not unusual and is an important predictor of mortality.

Pretransplant lymphopenia is a novel prognostic factor in cytomegalovirus and noncytomegalovirus invasive infections after liver transplantation.

Infection after liver transplantation (LT) remains a leading cause of morbidity and mortality. The risk of infection after LT is highest in those who are most immunosuppressed, but to date, no standard blood marker of one's degree of immunosuppression or risk index has been established. The purpose of this study was to determine whether pretransplant lymphopenia (absolute lymphocyte count < 500 cells/mm3 within 24 hours before LT) is a candidate marker of immunosuppression and could be useful in predicting the risk of cytomegalovirus (CMV) disease and non-CMV invasive infections after LT. Data were extracted from medical records for all primary, solitary LT procedures performed at Tufts Medical Center from 1999 to 2009. Two hundred seventy-six patients had sufficient data to be included in the analysis. Among these patients, 52% developed CMV or non-CMV invasive infections within 5 years of LT. Within 2 years, 23 (8%) had CMV disease, and 103 (37%) at least 1 non-CMV invasive infection. More lymphopenic patients than nonlymphopenic patients developed CMV (21% versus 4%, P < 0.001) and non-CMV invasive infections (50% versus 33%, P = 0.02). In a multivariate survival analysis, pretransplant lymphopenia was the strongest independent predictor of CMV disease [hazard ratio (HR) = 5.52, 95% confidence interval (CI) = 2.31-13.1, P = 0.001] after adjustments for known risk factors, including CMV serostatus (HR = 4.72, 95% CI = 2.01-11.1, P < 0.001). Both pretransplant lymphopenia (HR = 1.64, 95% CI = 1.14-2.53, P = 0.03) and CMV (HR = 2.93, 95% CI = 1.23-6.92, P = 0.02) independently predicted non-CMV infections. Our results suggest that pretransplant lymphopenia is a novel independent predictor of both CMV disease and non-CMV invasive infections after LT and is a candidate marker of immunosuppression in LT recipients.

Deceased donor risk factors influencing liver transplant outcome.

As the pressure for providing liver transplantation to more and more candidates increases, transplant programs have begun to consider deceased donor characteristics that were previously considered unacceptable. With this trend, attention has focused on better defining those donor factors that can impact the outcome of liver transplantation. This review examines deceased donor factors that have been associated with patient or graft survival as well as delayed graft function and other liver transplant results.

Ethical issues in organ transplantation.

We discuss ethical issues of organ transplantation including the stewardship tension between physicians' duty to do everything possible for their patients and their duty to serve society by encouraging organ donation. We emphasize consideration of the role of the principles of justice, utility and equity in the just distribution of transplantable organ as scarce resources. We then consider ethical issues of determining death of the organ donor including the remaining controversies in brain death determination and the new controversies raised by circulatory death determination. We need uniformity in standards of death determination, agreement on the duration of asystole before death is declared, and consensus on the allowable circulatory interventions on the newly declared organ donor that are intended to improve organ function. We discuss the importance of maintaining the dead donor rule, despite the argument of some scholars to abandon it.

A decade of model for end-stage liver disease: lessons learned and need for re-evaluation of allocation policies.

PURPOSE OF REVIEW: The model for end-stage liver disease (MELD) driven liver allocation system has been in place for 10 years now. Understanding what the driving forces were, what principles were developed and employed, and assessing how these have stood the test of time will help future policy makers further refine the system. RECENT FINDINGS: Prior to development of the MELD system, policymakers had limited data and organ allocation policy development was rarely systematic or evidence-based and was not necessarily centered on the patient. The MELD process focused on patient-specific variables and validation of the risk prediction models to be sure the system would function reasonably well across the spectrum of potential candidates and that it did not impose artificial categorizations of patients. In addition, the transplant community focused on assessing the effects of this policy change which was also something new. SUMMARY: Numerous publications since have reported outcomes for MELD-based liver allocation here in the United States and in many other areas around the world. Some of these reports have suggested changes to the MELD equation or other ways to adapt the system to more accurately reflect the need for transplant. The transparency that this type of system brings allows for much more rigorous assessment of results and for highlighting areas for improvement toward a more fair, equitable, and utilitarian system.