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Biomedical subjects

J Snow

Publications and source records attributed to J Snow.

At least 37 records · Page 2Linked to original sources
PubMed1993

Effects of stair-climbing vs run training on treadmill and track running performance.

Physically active college age women were evaluated to determine the effects of 9 wk of stair-climbing (Stairmaster Gauntlet) vs run training on 2414-m run time and treadmill measured aerobic capacity (VO2max) and submaximal physiological parameters. Subjects were randomly assigned to a stair-climbing (STAIR N = 11) (43.8 +/- 1.5 ml.kg-1.min-1) (mean +/- SEM) or run training (RUN N = 12) (44.2 +/- 1.8) group, training 4 d.wk-1 at 70-80% of maximum heart rate (MHR) for 30 min progressing to 85-90% MHR for 45 min. The STAIR group significantly increased (P < 0.01) their VO2max by 12% and decreased (P < 0.01) their 2414-m run time of 12.8 min by 8%. The RUN group increased (P < 0.01) their VO2max 16% and decreased run time (P < 0.01) 11% from 13.1 min. Submaximal treadmill runs at the same speed and grade demonstrated significant decreases in %VO2max and % MHR (P < 0.01) for both groups. The data support the use of stair-climbing exercise as an alternative mode to running with similar treadmill and running performance results subsequent to 9 wk of training.

Adult↗
PubMed1992

Soliciting hospital newsletter articles.

I keep my newsletter fairly brief and publish it quarterly, so I have plenty of time to practice my author-finding techniques between editions. This also gives me more time to come up with something on my own, if necessary. Although this article is presented in jest, I am not above anything that works to get contributions for my newsletter. Sometimes we editors are just that desperate.

Nursing Service, Hospital↗
PubMed1991

beta-NGF-endopeptidase: structure and activity of a kallikrein encoded by the gene mGK-22.

Mouse nerve growth factor (NGF) is cleaved at a histidine-methionine bond to release an NH2-terminal octapeptide (NGF1-8). The enzyme responsible, beta-NGF-endopeptidase, is structurally and functionally similar to gamma-NGF and epidermal growth factor-binding protein (EGF-BP) and cleaves mouse low molecular weight kininogen to produce bradykinin-like activity. These data have suggested that, like gamma-NGF and EGF-BP, beta-NGF-endopeptidase is a mouse glandular kallikrein. Evidence for a physiological role for NGF1-8 encouraged studies to further characterize the structure and function of this enzyme. Purified beta-NGF-endopeptidase migrated as a single band on isoelectric focusing and reducing SDS-polyacrylamide gels. As was expected, it removed NGF1-8 from NGF. Interestingly, enzymatic activity on an artificial substrate, and on NGF, was inhibited by NGF1-8 and by bradykinin. These studies further supported the view that beta-NGF-endopeptidase acts on both NGF and kininogen. The first 30 NH2-terminal amino acids of beta-NGF-endopeptidase were sequenced. This analysis demonstrated that the enzyme is encoded by the gene designated mGK-22 (Evans et al., 1987). The sequence of this gene corresponds to that of EGF-BP type A (Anundi et al., 1982; Drinkwater et al., 1987), and so studies were performed to determine whether or not beta-NGF-endopeptidase participates in EGF complex formation. Chromatographic and kinetic data gave no evidence that beta-NGF-endopeptidase is an EGF-binding protein. Our studies suggest that contamination of high molecular weight (HMW) EGF preparations with beta-NGF-endopeptidase erroneously led to earlier designation of the product of mGK-22 as an EGF-BP.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1990

Phase behavior of cholesteryl ester dispersions which model the inclusions of foam cells.

In order to understand the phase behavior of the approximately 1-micron-diameter droplets which occur in the cytoplasm of cholesterol-enriched cells, differential scanning calorimetry has been utilized to elucidate the factors controlling the rate of crystallization of cholesteryl esters. The kinetics of the thermotropic transitions between liquid, liquid-crystal, and crystal states which occur in mixtures of cholesteryl oleate and cholesteryl palmitate present in monodisperse, phospholipid-stabilized, emulsion droplets have been determined and are compared to the characteristics of these transitions in bulk mixtures. Cholesteryl palmitate is observed to crystallize in undercooled phospholipid-stabilized dispersions of cholesteryl palmitate/cholesteryl oleate (50/50 w/w) at temperatures up to 50 degrees C lower than it does in bulk mixtures of the same cholesteryl ester composition. It is postulated that this difference between crystallization temperatures is due primarily to the presence of impurities present in bulk mixtures which act as catalysts that promote crystallization. It is suggested that phospholipid-stabilized dispersions of cholesteryl palmitate/cholesteryl oleate are more appropriate models than bulk mixtures of these cholesteryl esters for studying the kinetic and thermodynamic basis of the phase behavior in cholesteryl ester rich inclusions characteristic of foam cells and atherosclerotic plaque. The thermotropic phase behavior of these dispersions can be satisfactorily analyzed by using the equations of homogeneous nucleation theory. The interfacial tension between the crystal nucleus and the surrounding fluid cholesteryl ester is about 10 erg/cm2.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Graded increases in brain GABA: differential effects on feeding and other behaviours in rats.

Elevations of brain gamma-aminobutyric acid (GABA) induced by inhibitors of GABA transaminase (GABA-T) are known to induce a number of functional effects including depression of food intake. The aim of the present study was to determine the brain GABA elevation threshold for changes in feeding and several other behaviours, in an effort to clarify whether feeding changes might be secondary to other functional deficits. To this end, various doses of the GABA-T inhibitors ethanolamine-o-sulfate (EOS) and gamma-vinyl GABA (GVG) were injected intracisternally and effects on whole brain GABA, food and water intake, open field activity, catalepsy indices, pain sensitivity, and core temperature were assessed 24 h later. Progressive increases in brain GABA levels were found to differentially affect the responses studied. At the low end of the continuum, significant decreases in feeding behaviour were associated with relatively modest increases in brain GABA (40-60%). At higher levels of GABA elevation (greater than 100%), changes in motoric functions and rectal temperature became apparent. At still higher levels (greater than 200% increases in brain GABA), significant antinociceptive effects were detected. These results support the notion that feeding decreases induced by low doses of GABA-T inhibitors may reflect a fairly specific effect on appetite mechanisms, but also indicate that with increasingly higher doses several other deficits are likely to contribute to the overall decrease in food intake.

4-Aminobutyrate Transaminase↗
PubMed1988

Variability of the pattern electroretinogram.

Conflicting results have been obtained concerning the parametric properties of the pattern electroretinogram. These discrepancies may be due to the large amount of variability inherent in recording amplitudes. We have found the variability within a single stimulus condition to be so large (ranging from 30% to 67% of the mean value) that it could mask any underlying spatial frequency tuning. Changing the stimulus conditions failed to significantly reduce the observed variability, although changing recording conditions produced some reduction. The use of a narrower rejection band, a greater number of sweeps, and placement of the reference electrode on the ipsilateral ear (as opposed to the ipsilateral temple) combined to decrease variability of the pattern electroretinogram within a single recording session; however, intersession variability remained high. Therefore one must be careful in evaluating data from this technique, and caution is advised in its clinical use.

Electroretinography↗
PubMed1986

Isolation and amino acid sequence of bovine platelet factor 4.

Bovine platelet factor 4 was isolated by affinity chromatography using dextran sulfate Sepharose and purified by subsequent gel filtration. The complete amino acid sequence of this 88-residue, 9505-Da protein was determined by isolation and analysis of the overlapping peptides from tryptic and Staphylococcus aureus hydrolysates of reduced, carboxymethylated, and reductive methylated protein. Primary structure comparison was made between bovine platelet factor 4, human platelet factor 4, and human beta-thromboglobulin. The bovine platelet factor 4 amino-terminal region, which contains two unique phenylalanine residues, is extended by 15 residues relative to human platelet factor 4. The bovine carboxy-terminal region is extended by three residues relative to human platelet factor 4 and differed from beta-thromboglobulin in the absence of two additional terminal residues. Bovine platelet factor 4 shares sequence similarities proportionately with both human platelet factor 4 and beta-thromboglobulin. The sequences of the lysine-rich carboxy-terminal putative heparin binding domains are essentially identical for all three proteins. The heparin neutralizing potencies of bovine and human platelet factor 4 are similar: 40 USP units of heparin neutralized per milligram protein, as measured by a modified chromogenic substrate assay. Heparin neutralization was lost by reduction of the disulfide bonds, but only attenuated by tryptic digestion of the intact protein.

Amino Acid Sequence↗
PubMed1986

Visual-spatial orientation, gaze direction and dichotic listening asymmetries.

The effects of visual-spatial orientation on dichotic listening performance were investigated in a sample of right-handed male and female adults. The 30 pairs of dichotic stimuli (/ba/ka/da/ga/ta/pa) were presented under three conditions: eye gaze fixed toward center, eye gaze directed 20 degrees to the right, and eye gaze directed 20 degrees to the left of center. Although no effect for gender or order was evident, a significant right ear advantage was found under all conditions. However, over all dichotic listening accuracy was significantly increased when visual-spatial orientation was directed to the right or left side of space.

Adult↗