Search PubMed⌕ Search

Biomedical subjects

B Shen

Publications and source records attributed to B Shen.

204 records · Page 12Linked to original sources
PubMed1984

In vitro effect of Triton WR-1339 on canine plasma high density lipoproteins.

We studied the effect in vitro of various concentrations of Triton WR-1339 on normolipidemic canine plasma and on the high density lipoproteins (HDL) isolated from this plasma by ultracentrifugation. As a preamble to this study, we established that Triton WR-1339 has a unimer molecular weight of 4,500, a micellar molecular weight of 180,000, and a critical micellar concentration (CMC) of 0.018 mM or 0.008 g/dl. Above its CMC, Triton WR-1339 in concentrations between 2 and 10 mg/ml induced concentration-dependent structural changes in HDL which were characterized by a progressive displacement of apoA-I from the HDL surface without loss of lipids. The addition of Triton WR-1339 to the HDL particles modified their electrophoresis mobility and caused an increase in size (95 +/- 5 A to 114 +/- 7 A). At the extreme Triton WR-1339 concentrations utilized in these studies (10 mg/ml) disruption of the HDL particles occurred; at this stage, the original, relatively homogeneous, spherical HDL particles were replaced by a heterogeneous population ranging in size between 50 and 250 A, representing complexes of Triton WR-1339 with lipids essentially free of apoA-I which could be sedimented by ultracentrifugation. The effects of Triton WR-1339 on whole plasma or isolated HDL were comparable. These studies indicate that Triton WR-1339 in vitro alters HDL in a concentration-dependent manner and that these changes vary from a displacement of apoA-I from the HDL surface to a state where all lipids are solubilized into the Triton WR-1339 micellar phase and are driven away from the protein moiety.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Post-preparedness medical disaster response in Costa Rica.

INTRODUCTION: The 1991 earthquake in the Limón area of Costa Rica presented the opportunity to examine the effectiveness of a decade of disaster preparedness. HYPOTHESIS: Costa Rica's concentrated work in disaster preparedness would result in significantly better management of the disaster response than was evident in earlier disasters in Guatemala and Nicaragua, where disaster preparedness largely was absent. METHODS: Structured interviews with disaster responders in and outside of government, and with victims and victims' neighbors. Clinical and epidemiologic data were collected through provider agencies and the coroner's office. RESULTS: Medical aspects of the disaster response were effective and well-managed through a network of clinic-based radio communications. Nonmedical aspects showed confusion resulting from: 1) poor government understanding of the roles and responsibilities of the central disaster coordinating agency; and 2) poor extension of disaster preparedness activities to the rural area that was affected by the earthquake. CONCLUSION: To be effective, disaster preparedness activities need to include all levels of government and rural, as well as urban, populations.

Costa Rica↗
PubMedDate not supplied

An analysis of prehospital mortality in an earthquake. Disaster Reanimatology Study Group.

INTRODUCTION: Anecdotal observations about prehospital emergency medical care in major natural and human-made disasters, such as earthquakes, have suggested that some injured victims survive the initial impact, but eventually die because of a delay in the application of life-saving medical therapy. METHODS: A multidisciplinary, retrospective structured interview methodology to investigate injury risk factors, and causes and circumstances of prehospital death after major disasters was developed. In this study, a team of United States researchers and Costa Rican health officials conducted a survey of lay survivors and health care professionals who participated in the emergency medical response to the earthquake in Costa Rica on 22 April 1991. RESULTS: Fifty-four deaths occurred prior to hospitalization (crude death rate = 0.4/1,000 population). Seventeen percent of these deaths (9/54) were of casualties who survived the initial impact but died at the scene or during transport. Twenty-two percent (2/9) were judged preventable if earlier emergency medical care had been available. Most injuries and deaths occurred in victims who were inside wooden buildings (p < .01) as opposed to other building types or were pinned by rubble from building collapse. Autopsies performed on a sample of victims showed crush injury to be the predominant cause of death. CONCLUSIONS: A substantial proportion of earthquake mortality in Costa Rica was protracted. Crush injury was the principal mechanism of injury and cause of death. The rapid institution of enhanced prehospital emergency medical services may be associated with a significant life-saving potential in these events.

Adolescent↗
PubMedDate not supplied

In vitro and in vivo interactions of Triton 1339 with plasma lipoproteins of normolipidemic rhesus monkeys. Preferential effects on high density lipoproteins.

Triton WR-1339 was incubated in vitro in various proportions with plasma from normolipidemic rhesus monkeys or with ultracentrifugally purified lipoproteins, and the products were examined by isopycnic density gradient ultracentrifugation, agarose column chromatography, electrophoretic and immunochemical techniques, and electron microscopy. Some experiments used apo A-I, apo A-II, or Triton labeled with either 125I or 131I. At concentrations of less than 10 mg/ml plasma, Triton interacted preferentially with HDL, changing lipoprotein size and density; Triton was progressively incorporated into the HDL particles, displacing apo E, apo A-I, and apo A-II. At concentrations above 10 mg/ml plasma, Triton displaced all apo A-I from the particle, and much lipid was dissolved into the Triton micelles. When Triton-treated HDL particles were used as a substrate for the enzyme LCAT, enzyme activity decreased in parallel to the displacement of apo A-I. There was no displacement of apo B from LDL nor any loss of lipids; but the particles became deformed and formed rouleaux. A single intravenous dose of Triton WR-1339 administered to a normolipidemic monkey (N) and to a hypercholesterolemic monkey (H) resulted in concentration-dependent HDL changes similar to those observed in vitro. LDL was less affected by Triton, with changes occurring only at high doses. After these structural changes, intravenously injected 131I apo A-I disappeared rapidly from the circulation; 125I apo A-II disappeared less rapidly. These increased clearances were accompanied by a drop in apo A-I plasma levels and the disappearance of HDL particles from plasma. The lipoprotein and apolipoprotein patterns returned to normal 14 days after Triton. We conclude that Triton WR-1339, when exposed to rhesus plasma in vitro or in vivo, interacts preferentially with HDL in a dose-dependent manner. At low concentrations, Triton acts on surface components of the HDL particle; at higher concentrations, Triton penetrates the particle, causing structural disruption. Because of its high affinity for HDL, Triton WR-1339 is a useful reagent for study of HDL structure-function relationships.

Animals↗
PubMedDate not supplied

Isolation and identification of chicken infectious anemia virus in China.

A chicken infectious anemia virus (CIAV) isolate was obtained from broiler flocks aged 25-40 days with anemia and poor performance and was designated SR43. The CIAV isolate was resistant to treatment with chloroform and induced thymus atrophy, bone marrow aplasia, and low hematocrit values when inoculated into 1-day-old, susceptible, specific-pathogen-free chicks. CIAV-specific antigens could be demonstrated in SR43-infected MDCC-MSB-1 cells, a cell line derived from a Marek's disease lymphoma, with the use of a monoclonal antibody specific for CIAV. CIAV DNA in infected MDCC-MSB-1 cell cultures was detected by using a polymerase chain reaction assay. These findings demonstrate that CIAV is present in China.

Animals↗