Large acceleration of alpha-chymotrypsin-catalyzed dipeptide formation by 18-crown-6 in organic solvents

The effects of 18-crown-6 on the synthesis of peptides catalyzed by alpha-chymotrypsin are reported. Lyophilization of the enzyme in the presence of 50 equivalents of 18-crown-6 results in a 425-fold enhanced activity when the reaction between the 2-chloroethylester of N-acetyl-L-phenylalanine and L-phenylalaninamide is carried out in acetonitrile. Addition of crown ether renders the dipeptide synthesis in nonaqueous solvents catalyzed by alpha-chymotrypsin possible on a preparative scale. The acceleration is observed in different solvents and for various peptide precursors. Copyright 1998 John Wiley & Sons, Inc.     

Regular exercise enhances insulin activation of IRS-1-associated PI3-kinase in human skeletal muscle.

Insulin action in skeletal muscle is enhanced by regular exercise. Whether insulin signaling in human skeletal muscle is affected by habitual exercise is not well understood. Phosphatidylinositol 3-kinase (PI3-kinase) activation is an important step in the insulin-signaling pathway and appears to regulate glucose metabolism via GLUT-4 translocation in skeletal muscle. To examine the effects of regular exercise on PI3-kinase activation, 2-h hyperinsulinemic (40 mU. m(-2). min(-1))-euglycemic (5.0 mM) clamps were performed on eight healthy exercise-trained [24 +/- 1 yr, 71.8 +/- 2.0 kg, maximal O(2) uptake (VO(2 max)) of 56.1 +/- 2.5 ml. kg(-1). min(-1)] and eight healthy sedentary men and women (24 +/- 1 yr, 64.7 +/- 4.4 kg, VO(2 max) of 44.4 +/- 2.7 ml. kg(-1). min(-1)). A [6, 6-(2)H]glucose tracer was used to measure hepatic glucose output. A muscle biopsy was obtained from the vastus lateralis muscle at basal and at 2 h of hyperinsulinemia to measure insulin receptor substrate-1(IRS-1)-associated PI3-kinase activation. Insulin concentrations during hyperinsulinemia were similar for both groups (293 +/- 22 and 311 +/- 22 pM for trained and sedentary, respectively). Insulin-mediated glucose disposal rates (GDR) were greater (P < 0.05) in the exercise-trained compared with the sedentary control group (9.22 +/- 0.95 vs. 6.36 +/- 0.57 mg. kg fat-free mass(-1). min(-1)). Insulin-stimulated PI3-kinase activation was also greater (P < 0.004) in the trained compared with the sedentary group (3.8 +/- 0.5- vs. 1.8 +/- 0.2-fold increase from basal). Endurance capacity (VO(2 max)) was positively correlated with PI3-kinase activation (r = 0.53, P < 0.04). There was no correlation between PI3-kinase and muscle morphology. However, increases in GDR were positively related to PI3-kinase activation (r = 0.60, P < 0.02). We conclude that regular exercise leads to greater insulin-stimulated IRS-1-associated PI3-kinase activation in human skeletal muscle, thus facilitating enhanced insulin-mediated glucose uptake.     

Differential cytokine response from dendritic cells to commensal and pathogenic bacteria in different lymphoid compartments in humans

Resident host microflora condition and prime the immune system. However, systemic and mucosal immune responses to bacteria may be divergent. Our aim was to compare, in vitro, cytokine production by human mononuclear and dendritic cells (DCs) from mesenteric lymph nodes (MLNs) and peripheral blood mononuclear cells (PBMCs) to defined microbial stimuli. Mononuclear cells and DCs isolated from the MLN (n = 10) and peripheral blood (n = 12) of patients with active colitis were incubated in vitro with the probiotic bacteria Lactobacillus salivarius UCC118 or Bifidobacterium infantis 35624 or the pathogenic organism Salmonella typhimurium UK1. Interleukin (IL)-12, tumor necrosis factor (TNF)-alpha, transforming growth factor (TGF)-beta, and IL-10 cytokine levels were quantified by ELISA. PBMCs and PBMC-derived DCs secreted TNF-alpha in response to the Lactobacillus, Bifidobacteria, and Salmonella strains, whereas MLN cells and MLN-derived DCs secreted TNF-alpha only in response to Salmonella challenge. Cells from the systemic compartment secreted IL-12 after coincubation with Salmonella or Lactobacilli, whereas MLN-derived cells produced IL-12 only in response to Salmonella. PBMCs secreted IL-10 in response to the Bifidobacterium strain but not in response to the Lactobacillus or Salmonella strain. However, MLN cells secreted IL-10 in response to Bifidobacteria and Lactobacilli but not in response to Salmonella. In conclusion, commensal bacteria induced regulatory cytokine production by MLN cells, whereas pathogenic bacteria induce T cell helper 1-polarizing cytokines. Commensal-pathogen divergence in cytokine responses is more marked in cells isolated from the mucosal immune system compared with PBMCs.     

Contributions of the hippocampus and medial prefrontal cortex to energy and body weight regulation

The effects of selective ibotenate lesions of the complete hippocampus (CHip), the hippocampal ventral pole (VP), or the medial prefrontal cortex (mPFC) in male rats were assessed on several measures related to energy regulation (i.e., body weight gain, food intake, body adiposity, metabolic activity, general behavioral activity, conditioned appetitive responding). The testing conditions were designed to minimize the nonspecific debilitating effects of these surgeries on intake and body weight. Rats with CHip and VP lesions exhibited significantly greater weight gain and food intake compared with controls. Furthermore, CHip-lesioned rats, but not rats with VP lesions, showed elevated metabolic activity, general activity in the dark phase of the light-dark cycle, and greater conditioned appetitive behavior, compared with control rats without these brain lesions. In contrast, rats with mPFC lesions were not different from controls on any of these measures. These results indicate that hippocampal damage interferes with energy and body weight regulation, perhaps by disrupting higher-order learning and memory processes that contribute to the control of appetitive and consummatory behavior.     

General and hybrid correlation nuclear magnetic resonance analysis of phosphorus in Phytophthora palmivora

As a specific tumor marker, prostate-specific antigen (PSA) is widely used for the early diagnosis of prostate cancer. Sensitive and specific methods are required to improve the diagnostic accuracy of PSA detection. In the current study, we compared the immuno-polymerase chain reaction (immuno-PCR) method with the solid-phase proximity ligation assay (SP-PLA) with respect to the detection of PSA. Using oligonucleotide-labeled antibody probes, we used both immuno-PCR and SP-PLA to detect trace levels of PSA. The nucleic acid sequences can be monitored using real-time PCR. SP-PLA, however, was found to be superior in terms of both the detection limit and the dynamic range. To detect even lower levels of PSA, we used the loop-mediated isothermal amplification (LAMP) method to measure the levels of reporter DNA molecules in SP-PLA. The sensitivity of the LAMP method is 0.001 pM, which is approximately 100-fold higher than the sensitivities of the other assays. The results suggest that an SP-PLA- and LAMP-based protocol with oligonucleotide-labeled antibody probes may have great application in detecting PSA or other proteins present at trace levels.     

On the Relationship Between Sea Level and Spartina alterniflora Production

A positive relationship between interannual sea level and plant growth is thought to stabilize many coastal landforms responding to accelerating rates of sea level rise. Numerical models of delta growth, tidal channel network evolution, and ecosystem resilience incorporate a hump-shaped relationship between inundation and plant primary production, where vegetation growth increases with sea level up to an optimum water depth or inundation frequency. In contrast, we use decade-long measurements of Spartina alterniflora biomass in seven coastal Virginia (USA) marshes to demonstrate that interannual sea level is rarely a primary determinant of vegetation growth. Although we find tepid support for a hump-shaped relationship between aboveground production and inundation when marshes of different elevation are considered, our results suggest that marshes high in the intertidal zone and low in relief are unresponsive to sea level fluctuations. We suggest existing models are unable to capture the behavior of wetlands in these portions of the landscape, and may underestimate their vulnerability to sea level rise because sea level rise will not be accompanied by enhanced plant growth and resultant sediment accumulation.     

Modelling the Impact of Condom Distribution on the Incidence and Prevalence of Sexually Transmitted Infections in an Adult Male Prison System

Aims

To determine the effects of 1) a condom distribution program and 2) a condom distribution program combined with opt-out sexually transmitted infection (STI) screening on the transmission and prevalence of STIs in a prison system.

Methods

Using data from an implementation evaluation of a state-wide prison condom program and parameter estimates from available literature, a deterministic model was developed to quantify the incidence and prevalence of sexually transmitted HIV, hepatitis B, chlamydia, syphilis and gonorrhoea across 14 Victorian prisons. The model included individual prison populations (by longer (>2 years) or shorter sentence lengths) and monthly prisoner transfers. For each STI, simulations were compared: without any intervention; with a condom distribution program; and with a combined condom and opt-out STI screening at prison reception intervention program.

Results

Condoms reduced the annual incidence of syphilis by 99% (N = 66 averted cases); gonorrhoea by 98% (N = 113 cases); hepatitis B by 71% (N = 5 cases); chlamydia by 27% (N = 196 cases); and HIV by 50% (N = 2 cases every 10 years). Condom availability changed the in-prison epidemiology of gonorrhoea and syphilis from self-sustaining to levels unlikely to result in infection outbreaks; however, condoms did not reduce chlamydia prevalence below a self-sustaining level due to its high infectiousness, high prevalence and low detection rate. When combined with a screening intervention program, condoms reduced chlamydia prevalence further, but not below a self-sustaining level. The low prevalence of HIV and hepatitis B in Australian prisons meant the effects of condoms were predicted to be small.

Conclusion

Condoms are predicted to effectively reduce the incidence of STIs in prison and are predicted to control syphilis and gonorrhoea transmission, however even combined with a screening on arrival program may be insufficient to reduce chlamydia prevalence below self-sustaining levels. To control chlamydia transmission additional screening of the existing prison population would be required.     

Immunochemical detection and characterization of pregnancy-associated endometrial alpha 1- and alpha 2-globulins secreted by human endometrium and decidua

Antisera raised against the soluble antigens of the endometrium of early pregnancy detected two antigenic proteins of alpha 1 and alpha 2 mobility in extracts of this tissue and were termed antigens A and B. Neither antigen was detected in pregnancy sera or extracts of proliferative endometrium, but antigen B was detected in extracts of secretory endometrium and both were present in amniotic fluid and medium from in-vitro incubations of pregnancy endometrium. Fractionation of radiolabelled medium on ion-exchange chromatography demonstrated that antigens A and B co-eluted with the proteins from which EP14 and EP15 were derived and which were the major secretory polypeptides of pregnancy endometrium in vitro. Further biochemical purification revealed that EP14 (Mr 32 000) was derived from a protein of native molecular weight 36 000 which existed in two forms, whereas EP15 (Mr 28 000) was derived from a dimeric glycoprotein of native molecular weight 56 000. Immunochemical studies demonstrated that antigens A and B are identical to these two secretory proteins and have been termed pregnancy-associated endometrial alpha 1- and alpha 2-globulins (alpha 1- and alpha 2-PEG).