Browsing by Subject "History, 21st Century"
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Item Open Access A tale of two callings.(J Clin Invest, 2011-10) Lefkowitz, Robert JItem Open Access Global nitrogen budgets in cereals: A 50-year assessment for maize, rice, and wheat production systems.(Scientific reports, 2016-01-18) Ladha, JK; Tirol-Padre, A; Reddy, CK; Cassman, KG; Verma, Sudhir; Powlson, DS; van Kessel, C; de B Richter, Daniel; Chakraborty, Debashis; Pathak, HimanshuIndustrially produced N-fertilizer is essential to the production of cereals that supports current and projected human populations. We constructed a top-down global N budget for maize, rice, and wheat for a 50-year period (1961 to 2010). Cereals harvested a total of 1551 Tg of N, of which 48% was supplied through fertilizer-N and 4% came from net soil depletion. An estimated 48% (737 Tg) of crop N, equal to 29, 38, and 25 kg ha(-1) yr(-1) for maize, rice, and wheat, respectively, is contributed by sources other than fertilizer- or soil-N. Non-symbiotic N2 fixation appears to be the major source of this N, which is 370 Tg or 24% of total N in the crop, corresponding to 13, 22, and 13 kg ha(-1) yr(-1) for maize, rice, and wheat, respectively. Manure (217 Tg or 14%) and atmospheric deposition (96 Tg or 6%) are the other sources of N. Crop residues and seed contribute marginally. Our scaling-down approach to estimate the contribution of non-symbiotic N2 fixation is robust because it focuses on global quantities of N in sources and sinks that are easier to estimate, in contrast to estimating N losses per se, because losses are highly soil-, climate-, and crop-specific.Item Open Access 'One physical system': Tansley's ecosystem as Earth's critical zone.(The New phytologist, 2015-05) Richter, Daniel deB; Billings, Sharon AIntegrative concepts of the biosphere, ecosystem, biogeocenosis and, recently, Earth's critical zone embrace scientific disciplines that link matter, energy and organisms in a systems-level understanding of our remarkable planet. Here, we assert the congruence of Tansley's (1935) venerable ecosystem concept of 'one physical system' with Earth science's critical zone. Ecosystems and critical zones are congruent across spatial-temporal scales from vegetation-clad weathering profiles and hillslopes, small catchments, landscapes, river basins, continents, to Earth's whole terrestrial surface. What may be less obvious is congruence in the vertical dimension. We use ecosystem metabolism to argue that full accounting of photosynthetically fixed carbon includes respiratory CO₂ and carbonic acid that propagate to the base of the critical zone itself. Although a small fraction of respiration, the downward diffusion of CO₂ helps determine rates of soil formation and, ultimately, ecosystem evolution and resilience. Because life in the upper portions of terrestrial ecosystems significantly affects biogeochemistry throughout weathering profiles, the lower boundaries of most terrestrial ecosystems have been demarcated at depths too shallow to permit a complete understanding of ecosystem structure and function. Opportunities abound to explore connections between upper and lower components of critical-zone ecosystems, between soils and streams in watersheds, and between plant-derived CO₂ and deep microbial communities and mineral weathering.Item Open Access Q Fever, Scrub Typhus, and Rickettsial Diseases in Children, Kenya, 2011-2012.(Emerg Infect Dis, 2016-05) Maina, Alice N; Farris, Christina M; Odhiambo, Antony; Jiang, Ju; Laktabai, Jeremiah; Armstrong, Janice; Holland, Thomas; Richards, Allen L; O'Meara, Wendy PTo increase knowledge of undifferentiated fevers in Kenya, we tested paired serum samples from febrile children in western Kenya for antibodies against pathogens increasingly recognized to cause febrile illness in Africa. Of patients assessed, 8.9%, 22.4%, 1.1%, and 3.6% had enhanced seroreactivity to Coxiella burnetii, spotted fever group rickettsiae, typhus group rickettsiae, and scrub typhus group orientiae, respectively.Item Open Access Reduction in Mortality after Umbilical Cord Blood Transplantation in Children Over a 20-Year Period (1995-2014).(Biology of blood and marrow transplantation : journal of the American Society for Blood and Marrow Transplantation, 2019-04) Spees, Lisa P; Martin, Paul L; Kurtzberg, Joanne; Stokhuyzen, Andre; McGill, Lauren; Prasad, Vinod K; Driscoll, Timothy A; Parikh, Suhag H; Page, Kristin M; Vinesett, Richard; Severyn, Christopher; Sung, Anthony D; Proia, Alan D; Jenkins, Kirsten; Arshad, Mehreen; Steinbach, William J; Seed, Patrick C; Kelly, Matthew SInfections and graft-versus-host disease (GVHD) have historically resulted in high mortality among children undergoing umbilical cord blood transplantation (UCBT). However, recent advances in clinical practice have likely improved outcomes of these patients. We conducted a retrospective cohort study of children (<18years of age) undergoing UCBT at Duke University between January 1, 1995 and December 31, 2014. We compared 2-year all-cause and cause-specific mortality during 3 time periods based on year of transplantation (1995 to 2001, 2002 to 2007, and 2008 to 2014). We used multivariable Cox regression to identify demographic and UCBT characteristics that were associated with all-cause mortality, transplantation-related mortality, and death from invasive aspergillosis after adjustment for time period. During the 20-year study period 824 children underwent UCBT. Two-year all-cause mortality declined from 48% in 1995 to 2001 to 30% in 2008 to 2014 (P = .0002). White race and nonmalignant UCBT indications were associated with lower mortality. Black children tended to have a higher risk of death for which GVHD (18% versus 11%; P = .06) or graft failure (9% versus 3%; P = .01) were contributory than white children. Comparing 2008 to 2014 with 1995 to 2001, more than half (59%) of the reduced mortality was attributable to a reduction in infectious mortality, with 45% specifically related to reduced mortality from invasive aspergillosis. Antifungal prophylaxis with voriconazole was associated with lower mortality from invasive aspergillosis than low-dose amphotericin B lipid complex (hazard ratio, .09; 95% confidence interval, .01 to .76). With the decline in mortality from invasive aspergillosis, adenovirus and cytomegalovirus have become the most frequentinfectious causes of death in children after UCBT. Advances in clinical practice over the past 20years improved survival of children after UCBT. Reduced mortality from infections, particularly invasive aspergillosis, accounted for the largest improvement in survival and was associated with use of voriconazole for antifungal prophylaxis.Item Open Access Steep increase in best-practice cohort life expectancy.(Popul Dev Rev, 2011) Shkolnikov, Vladimir M; Jdanov, Dmitri A; Andreev, Evgeny M; Vaupel, James WWe analyze trends in best-practice life expectancy among female cohorts born from 1870 to 1950. Cohorts experience declining rather than constant death rates, and cohort life expectancy usually exceeds period life expectancy. Unobserved mortality rates in non-extinct cohorts are estimated using the Lee-Carter model for mortality in 1960–2008. Best-practice cohort and period life expectancies increased nearly linearly. Across cohorts born from 1870 to 1920 the annual increase in cohort length of life was 0.43 years. Across calendar years from 1870 to 2008, the annual increase was 0.28 years. Cohort life expectancy increased from 53.7 years in the 1870 cohort to 83.8 years in the 1950 cohort. The corresponding cohort/period longevity gap increased from 1.2 to 10.3 years. Among younger cohorts, survival to advanced ages is substantially higher than could have been anticipated by period mortality regimes when these cohorts were young or middle-aged. A large proportion of the additional expected years of life are being lived at ages 65 and older. This substantially changes the balance between the stages of the life cycle.Item Open Access The annual ASCI meeting: does nostalgia have a future?(J Clin Invest, 2008-04) Lefkowitz, Robert JFor many academic physician-scientists, the yearly Tri-Societies meeting of the ASCI, AAP, and AFCR during the 1960s, '70s, and '80s was an annual rite of spring and the focal point of the academic year. In this brief essay, I set down some miscellaneous recollections of these meetings and some thoughts about why they were of such central importance in the careers of those of my generation.Item Open Access The State of Infectious Diseases Clinical Trials: A Systematic Review of ClinicalTrials.gov(PLoS ONE, 2013-10-16) Goswami, ND; Pfeiffer, CD; Horton, JR; Chiswell, K; Tasneem, A; Tsalik, ELBackgroundThere is a paucity of clinical trials informing specific questions faced by infectious diseases (ID) specialists. The ClinicalTrials.gov registry offers an opportunity to evaluate the ID clinical trials portfolio.
MethodsWe examined 40,970 interventional trials registered with ClinicalTrials.gov from 2007–2010, focusing on study conditions and interventions to identify ID-related trials. Relevance to ID was manually confirmed for each programmatically identified trial, yielding 3570 ID trials and 37,400 non-ID trials for analysis.
ResultsThe number of ID trials was similar to the number of trials identified as belonging to cardiovascular medicine (n = 3437) or mental health (n = 3695) specialties. Slightly over half of ID trials were treatment-oriented trials (53%, vs. 77% for non-ID trials) followed by prevention (38%, vs. 8% in non-ID trials). ID trials tended to be larger than those of other specialties, with a median enrollment of 125 subjects (interquartile range [IQR], 45–400) vs. 60 (IQR, 30–160) for non-ID trials. Most ID studies are randomized (73%) but nonblinded (56%). Industry was the funding source in 51% of ID trials vs. 10% that were primarily NIH-funded. HIV-AIDS trials constitute the largest subset of ID trials (n = 815 [23%]), followed by influenza vaccine (n = 375 [11%]), and hepatitis C (n = 339 [9%]) trials. Relative to U.S. and global mortality rates, HIV-AIDS and hepatitis C virus trials are over-represented, whereas lower respiratory tract infection trials are under-represented in this large sample of ID clinical trials.
ConclusionsThis work is the first to characterize ID clinical trials registered in ClinicalTrials.gov, providing a framework to discuss prioritization, methodology, and policy.
Item Open Access The Wesselhoefts: A medical dynasty from the age of Goethe to the era of nuclear medicine.(Journal of medical biography, 2017-11) Davidson, Jonathan RtFor six generations, members of the Wesselhoeft family have practiced medicine in Germany, Denmark, Switzerland, Canada and/or the USA. In the early decades of the 19th century, two Wesselhoeft brothers left Europe to eventually settle in New England, where they and their progeny gave rise to a regional medical dynasty. The Wesselhoeft doctors became well-known practitioners of homeopathy, hydropathy, conventional medicine and surgery, in academic and general clinical settings. An additional connection was established to the literary worlds of Germany and the USA, either through friendships or as personal physicians.