Measurement and Utilization of In Vivo Blood-Pressure Transfer Functions of Dog and Chicken Aortas

A method for determining the essential parameters of the aorta, namely the geometric taper, area, hoop elasticity, and effective loss factor, from in vivo pressure measurements is presented. A nonuniform hybrid model, having both geometric and elastic taper and terminated in a reflectionless impedance at the femoral bifurcation, is utilized.     

Phosphorus limits phytoplankton growth on the Louisiana shelf during the period of hypoxia formation

The Louisiana shelf is the largest zone of seasonally oxygen-depleted coastal bottom water in the U.S. This condition results from the high freshwater and nutrient input from the Mississippi River and the resulting high primary productivity in the river plume. The hypoxic zone has doubled in area since regular measurements began in 1985. Identification of the nutrient(s) limiting phytoplankton growth on the shelf and their sources is important for developing hypoxia-reduction strategies; nitrogen (N) has been considered the most important to date. In this study, we measured multiple parameters addressing nutrient limitation or stress (nutrient concentrations and ratios, alkaline phosphatase activity, phosphorus (P)turnover times, and changes in chlorophyll a concentrations in nutrient enrichment bioassays) in the Mississippi River plume in March, May, July, and September of 2001. All results indicate that phytoplankton growth on the Louisiana shelf was limited by P in May and July of 2001. P limitation was weakly evident in March, but N was limiting in September. The observed P limitation in spring and summer probably results from the historical increases in riverine N due to excessive N loading and has potential implications for developing hypoxia reduction strategies.     

Quantitative assessment of IgM antibodies towards an immunodominant B-cell epitope within the preS2 domain of HBV in the natural course and during combined prednisone/interferon alpha 2b treatment of chronic hepatitis B virus infection

A direct binding enzyme-linked immunosorbent assay (ELISA) was established for quantitative determination of serum IgM antibodies towards a synthetic peptide corresponding to a selected segment (14-21) of the preS2-gene product containing an immunodominant linear B-cell epitope. The prevalence of IgM anti-preS2 (14-21) antibody titers > 1,000 for hepatitis B e antigen (HBeAg)-positive patients with chronic hepatitis B virus (HBV) infection was 38% (22/58) and 10% (2/21) for HBeAg-negative subjects (P < 0.005). IgM anti-preS2 (14-21) reactivity was detected during the clinical course of chronic HBV infection and IgM anti-peptide antibody titers declined and disappeared before spontaneous HBe/anti-HBe seroconversion. Recombinant interferon (IFN)-alpha 2b with an antecedent short course of corticosteroids was administered to eight Chinese patients with chronic HBV infection. The IgM anti-preS2 (14-21) reactivity was monitored consecutively during treatment and patients were followed for more than 1 year. A close association between the presence of pretreatment IgM anti-preS2 (14-21) in serum and the capacity to respond favorably to the combined prednisone/IFN-alpha 2b therapy was detected. The IgM anti-preS2 (14-21) titers decreased during treatment with subsequent loss of detectable antibodies 8-16 weeks after the initiation of therapy. This decrease was concomitant with an alanine aminotransferase (ALT) augmentation preceding the disappearance of HBV-DNA and anti-HBe seroconversion. Long-term remission was not observed in treated patients who lacked detectable levels of pretreatment IgM anti-preS2 (14-21) in the circulation.(ABSTRACT TRUNCATED AT 250 WORDS)