University of California, San Diego

About: University of California, San Diego is a education organization based out in San Diego, California, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 83317 authors who have published 204524 publications receiving 12315489 citations. The organization is also known as: UCSD & UC San Diego.

Atmospheric brown clouds: impacts on South Asian climate and hydrological cycle.

Abstract: South Asian emissions of fossil fuel SO2 and black carbon increased≈6-fold since 1930, resulting in large atmospheric concentrations of black carbon and other aerosols. This period also witnessed strong negative trends of surface solar radiation, surface evaporation, and summer monsoon rainfall. These changes over India were accompanied by an increase in atmospheric stability and a decrease in sea surface temperature gradients in the Northern Indian Ocean. We conducted an ensemble of coupled ocean-atmosphere simulations from 1930 to 2000 to understand the role of atmospheric brown clouds in the observed trends. The simulations adopt the aerosol radiative forcing from the Indian Ocean experiment observations and also account for global increases in greenhouse gases and sulfate aerosols. The simulated decreases in surface solar radiation, changes in surface and atmospheric temperatures over land and sea, and decreases in monsoon rainfall are similar to the observed trends. We also show that greenhouse gases and sulfates, by themselves, do not account for the magnitude or even the sign in many instances, of the observed trends. Thus, our simulations suggest that absorbing aerosols in atmospheric brown clouds may have played a major role in the observed regional climate and hydrological cycle changes and have masked as much as 50% of the surface warming due to the global increase in greenhouse gases. The simulations also raise the possibility that, if current trends in emissions continue, the subcontinent may experience a doubling of the drought frequency in the coming decades.

Prevalence of Fatty Liver in Children and Adolescents

Abstract: OBJECTIVE.Fatty liver disease is diagnosed increasingly in children, but the prevalence remains unknown. We sought to determine the prevalence of pediatric fatty liver as diagnosed by histology in a population-based sample. METHODS.We conducted a retrospective review of 742 children between the ages of 2 and 19 years who had an autopsy performed by a county medical examiner from 1993 to 2003. Fatty liver was defined as 5% of hepatocytes containing macrovesicular fat. RESULTS.Fatty liver was present in 13% of subjects. For children and adolescents age 2 to 19 years, the prevalence of fatty liver adjusted for age, gender, race, and ethnicity is estimated to be 9.6%. Fatty liver prevalence increases with age, ranging from 0.7% for ages 2 to 4 up to 17.3% for ages 15 to 19 years. Fatty liver prevalence differs significantly by race and ethnicity (Asian: 10.2%; black: 1.5%; Hispanic: 11.8%; white: 8.6%). The highest rate of fatty liver was seen in obese children (38%). CONCLUSIONS.Fatty liver is the most common liver abnormality in children age 2 to 19 years. The presence of macrovesicular hepatic steatosis in 1 of every 10 children has important ramifications for the long-term health of children and young adults. The influence of the risk factors identified should be taken into consideration in the development of protocols designed to screen at-risk children and adolescents.

Ocean Deoxygenation in a Warming World

Abstract: Ocean warming and increased stratification of the upper ocean caused by global climate change will likely lead to declines in dissolved O2 in the ocean interior (ocean deoxygenation) with implications for ocean productivity, nutrient cycling, carbon cycling, and marine habitat. Ocean models predict declines of 1 to 7% in the global ocean O2 inventory over the next century, with declines continuing for a thousand years or more into the future. An important consequence may be an expansion in the area and volume of so-called oxygen minimum zones, where O2 levels are too low to support many macrofauna and profound changes in biogeochemical cycling occur. Significant deoxygenation has occurred over the past 50 years in the North Pacific and tropical oceans, suggesting larger changes are looming. The potential for larger O2 declines in the future suggests the need for an improved observing system for tracking ocean O2 changes.

IL-4 directs the development of Th2-like helper effectors.

Abstract: Our studies show that the presence of IL-4 during the response of naive Th cells causes precursors to develop into a population comprised largely of "Th2-like" effectors that secrete IL-4 and IL-5, but little IL-2 or IFN-gamma We find that the levels of IL-4 and IL-2 determine both the level of effectors developed in response to mitogen or Ag and the patterns of lymphokines they secrete when restimulated IL-2 is required for optimum generation of effectors, and increasing levels of IL-2, augments the expansion of effectors secreting both IL-4/IL-5 and IFN-gamma In contrast, IL-4 is required for the development of IL-4/IL-5 secreting effectors but suppresses the development of IL-2 and at higher doses IFN-gamma-secreting effectors detected after 4 days Also dramatic are the effects of the presence or absence of IL-4 evaluated after an additional 1 to 2 wk When cultures with or without initial IL-4 are cultured in IL-2 alone from days 4 to 11, they retain their distinct patterns of lymphokine production Those cells that developed in cultures without IL-4 progressively secrete more IL-2 and can be maintained and expanded in IL-2 They continue to produce IFN-gamma, though the levels decrease somewhat with time, but they do not acquire the ability to produce IL-4 or IL-5 These cells thus increasingly resemble Th1 cell lines In contrast, those cells in cultures initially exposed to IL-4, generate effectors which secrete high levels of IL-4/IL-5 (plus variable levels of IFN-gamma) at days 4 to 5, but the populations of cells developed, are not maintained well on IL-2 alone Those cells that do survive continue to secrete IL-4 and IL-5 but not IL-2 In addition, IFN-gamma production, if present, falls off with time Thus the cells in these cultures take on an increasingly Th2-like phenotype It appears that the effects of low levels of IL-4 in suppressing IL-2 production by day 4 effectors appear to be transient whereas the higher levels appear to drive the development along a distinct pathway which is irreversible These studies support the concept that different subsets of helper cells, which correspond roughly to Th1 and Th2 subsets, can develop rapidly in short term culture with respectively low vs high levels of IL-4 They support the concept that such distinct phenotypes arise from alternate pathways of differentiation that can be expected to reflect pathways available for helper T cell differentiation in the animal