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Biomedical subjects

C Stevens

Publications and source records attributed to C Stevens.

At least 145 records · Page 8Linked to original sources
PubMed1988

Diagnosis and clinical manifestations of bacterial vaginosis.

Among 640 randomly selected women who were attending a sexually transmitted disease clinic and did not have trichomoniasis, 33% had bacterial vaginosis as defined by a composite of four clinical criteria: (1) Vaginal discharge was homogeneous; (2) vaginal discharge had a pH greater than or equal to 4.7; (3) vaginal discharge had an amine-like odor when mixed with 10% potassium hydroxide; (4) vaginal discharge contained clue cells representing greater than or equal to 20% of vaginal epithelial cells. Previously published Gram stain criteria for bacterial vaginosis correlated better than results of semiquantitative cultures for Gardnerella vaginalis with presence or absence of clue cells and with composite clinical criteria. Of 293 women with bacterial vaginosis by Gram stain criteria, 65% had symptoms of increased vaginal discharge and/or vaginal malodor, while 74% had signs of characteristic homogeneous vaginal discharge or amine-like odor. Elevated vaginal pH was the least specific and amine-like odor the least sensitive sign of bacterial vaginosis. Gram stain criteria for bacterial vaginosis were not associated with the concentrations of endocervical or vaginal inflammatory cells but were significantly associated with a clinical diagnosis of pelvic inflammatory disease. After adjusting for coinfection, sexual behavior, and other variables, bacterial vaginosis remained associated with adnexal tenderness (odds ratio = 9.2, p = 0.04). Bacterial vaginosis, previously implicated as a risk factor for obstetric infections, may be a risk factor for pelvic inflammatory disease.

Bacterial Infections↗
PubMed1988

Hepatitis B vaccines in patients with chronic renal failure before dialysis.

Hepatitis B remains a significant risk to patients receiving chronic hemodialysis, but no certain method of prevention has been identified. We tested two vaccines, plasma-derived vaccine (40-micrograms dose) and recombinant-derived vaccine (40-micrograms and 20-micrograms doses), in 61 patients with chronic renal failure who were not yet dependent on dialysis. Patients were followed up clinically and with laboratory tests of kidney function and hepatitis B virus serology for one year. Significantly more recipients of plasma-derived vaccine responded to vaccination; they also achieved a higher titer of antibody to hepatitis B virus than did recipients of recombinant-derived vaccine when evaluated at 6, 7, 9, and 12 mo after vaccination. No serious side effects were observed with any vaccine preparation, nor were excessive adverse effects observed in any group. Compared with the dialysis patients previously studied, patients with renal failure who were not yet dependent on dialysis responded more favorably to the hepatitis B virus vaccine.

Adult↗
PubMed1987

Calcium antagonists and heat-induced hepatic injury.

Several laboratories have demonstrated the value of the isolated perfused rat liver as a suitable model for heat-induced hepatic injury in vivo. Membrane changes caused by perfusion of rat livers at 42 degrees C for 90 min were similar to those induced by toxic chemicals or hypoxia. In an evaluation of several categories of drugs reported to reduce cell injury, calcium antagonists (nifedipine, dantrolene, and verapamil), were evaluated for their therapeutic potential for heat injury. Isolated rat livers were perfused at 42 degrees C for 90 min with and without calcium antagonists. Livers were also perfused at 37 degrees C. Potassium and transaminase leakage, bile production and ultrastructure were used to evaluate their responses. Neither of the three calcium antagonists significantly improved any of the functional parameters measured. However, dantrolene produced dilated or vesicular rough endoplasmic reticulum in the heated livers. These changes suggest selective intracellular action on endoplasmic reticulum of heated livers. Ring-shaped mitochondria and vesicular endoplasmic reticulum were observed in the heated, verapamil-treated livers, but these could not be quantitatively distinguished from controls. Nifedipine did not appear to alter intracellular membranes, but did increase bile production.

Animals↗
PubMed1987

Studies on aorta during development. II. Differences in ontogeny of the key enzymes involved in cholesteryl ester synthesis and hydrolysis in rabbit aorta.

It is well known that cholesteryl ester accumulation is dramatically increased in the atherosclerotic artery. The enzymes acyl-CoA: cholesterol acyltransferase (ACAT), acid cholesteryl esterase (ACE) and neutral cholesteryl esterase (NCE) may play key roles in the accumulation of cholesteryl esters in the arterial wall. However, very little is known regarding the developmental pattern of the key enzymes involved in cholesteryl ester synthesis and hydrolysis. The total activities of ACAT, ACE and NCE were measured by radioassay using liposomal substrates in rabbit aortic homogenates. Our results indicate that ACAT activity decreases as a quadratic function with age (P less than 0.05). ACAT activity (pmol/100 mg protein/min) decreased from a high value in the fetus at term (63.3 +/- 7.4) to gradually lower values with increasing age. On the other hand, ACE activity (pmol/mg protein/min) was low in the fetus at term, and changed as a quadratic function with age (P less than 0.05) increasing gradually to higher activities with age up to a maximum at 12 weeks then decreased at 21 weeks. NCE activity (pmol/mg protein/min) increased dramatically from a low value in the fetus at term (3.34 +/- 0.48) to a maximum value at 1.5 weeks (14.65 +/- 2.73) then decreased as a linear function with increasing age up to 21 weeks (P less than 0.05). Plasma total cholesterol (mg/dl) also increased sharply from the fetal value at term of 98.5 +/- 5.2 to a maximum value at 1.5 weeks of 666.4 +/- 33.4, then decreased as a quadratic function with increasing age up to 21 weeks (40.8 +/- 6.7) (P less than 0.05). The free cholesterol content (microgram/mg protein) of the aortic tissue was initially high in the fetus (24.8 +/- 5.9) then increased with age. Examination of the ratio of synthesis to hydrolysis of cholesteryl esters as an index of enzyme activity units demonstrated a very high index in the fetus of 6.1 that rapidly decreased with increasing age in the young adult rabbit down to a value of 0.4 by 21 weeks of age. Correlation coefficients between enzyme activities, plasma cholesterol levels and aortic cholesterol levels indicated (a) a positive correlation of NCE activity with plasma cholesterol, (b) a negative correlation of NCE and ACE with aortic-cholesteryl ester content, and (c) no significant correlation of ACAT activity with either plasma cholesterol or aortic cholesterol content, indicating other factors are involved.(ABSTRACT TRUNCATED AT 400 WORDS)

Age Factors↗
PubMed1987

Analysis of human serum antibodies to human immunodeficiency virus (HIV) using recombinant ENV and GAG antigens.

Recombinant proteins representing gag and env amino acid sequences of the Human Immunodeficiency Virus (HIV) (HTLV-IIIb) were produced in Escherichia coli and used to analyze sera for the presence of antibodies to HIV. ENV-9 is a protein representing the carboxy terminus of gp120 and part of gp41 which is highly immunoreactive. GAG-1 represents 83% and GAG-55 100% of the amino acids of the gag open reading frame. The purified proteins allow sensitive detection by enzyme linked immunosorbent assay (ELISA) of antibodies directed against either env or gag of HIV. We have determined the reactivity of sera from several HIV exposed individuals, either form high risk populations or with clinically defined conditions, in the ENV-9, GAG-55, and GAG-1 assays and found that two major seropositive groups are observed. The quantitative analysis of sera with env and gag antigens by ELISA showed AIDS patients had very low gag reactivity while retaining high env reactivity. Results obtained with authentic p24 viral protein in both ELISA and radioimmunoassay correlated to those from the GAG-55 ELISA. This correlation and the analysis of sera with both the ENV and GAG ELISAs indicate that the antibodies reactive to gag are specifically affected relative to env reactivity and that different levels of antibodies to separate viral components in these sera may correlate with disease state.

Acquired Immunodeficiency Syndrome↗
PubMed1987

The isolation of spiroplasmas from mosquitoes in Macon County, Alabama.

During the summer months of 1985, 1,298 adult mosquitoes comprising 21 species and 7 genera were collected in Macon County, Alabama. Mosquitoes were collected from four sections of the county with CO2-baited light traps. Spiroplasma cultures were isolated from two pools of 24 and 25 Aedes fulvus pallens, one pool of 22 Anopheles punctipennis and one pool of 7 Culex nigripalpus. Electron microscopic studies of the isolates revealed helical, wall-less cells.

Alabama↗