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Biomedical subjects

J W Byron

Publications and source records attributed to J W Byron.

At least 19 recordsLinked to original sources
PubMed1997

Mucosal immune responses in four distinct compartments of women infected with human immunodeficiency virus type 1: a comparison by site and correlation with clinical information.

Because mucosal immune responses may be important in protection against human immunodeficiency virus type 1 (HIV-1), HIV-1-specific immune responses at mucosal sites in natural infection were compared. Total antibody concentrations and HIV-1-specific binding antibody responses in four distinct mucosal sites and serum were assessed in 41 HIV-infected and 19 HIV-seronegative women. HIV-1 gp160-specific IgG responses were detected in >99% of mucosal samples in infected subjects, with the highest titers in genital secretions. HIV-1-specific IgA was detected in the majority of endocervical secretions (94%) and nasal washes (95%) but less often in vaginal washes (51%) and parotid saliva (38%). There was no significant correlation between mucosal immune response and most clinical factors. Based on methodologic considerations, frequencies of detection, and HIV-1-specific responses, nasal washes and genital secretions may each provide important measures of HIV-1-specific mucosal immune responses in infected women.

Adult↗
PubMed1993

A randomized comparison of Verres needle and direct trocar insertion for laparoscopy.

Two hundred and fifty-two women scheduled to undergo laparoscopy were randomly assigned to a Verres needle or direct insertion group. The groups were similar with respect to incidence of obesity, prior surgical treatment, indication for operation and level of training of the surgeon performing the procedure. There were no major complications associated with either technique. Minor complications (preperitoneal insufflation, failed entry or more than three attempts necessary to enter the peritoneal cavity with the trocar) were significantly more frequent (p < 0.05) in the Verres needle technique group. One hundred and thirteen of these patients underwent sterilization procedures. The mean times for performance of the laparoscopic procedure using the direct insertion and Verres needle techniques was 15.3 and 19.6 minutes, respectively. The time saved using the direct insertion technique is explained by a significant (p < 0.01) reduction in the mean laparoscope insertion time, which was 2.2 minutes and 5.9 minutes for the direct insertion and Verres needle techniques, respectively. We prefer the direct insertion technique for trocar placement because it has fewer minor complications and requires less operating time.

Female↗
PubMed1989

Evaluation of the direct trocar insertion technique at laparoscopy.

A technique using direct trocar insertion for laparoscopy was introduced into the Tripler Army Medical Center Obstetrics and Gynecology training program in September 1982. From January 1, 1983 to December 31, 1985, a total of 1249 laparoscopic procedures were performed. Detailed records of 937 laparoscopic procedures performed using this technique were reviewed. The technique was used with increasing frequency: 40% in 1983, 85% in 1984, and 96% of all laparoscopies in 1985. There were no major complications. With increased departmental experience, the frequency of minor complications decreased: 5.3% in 1983, 5.0% in 1984, and 1.3% in 1985. Obesity was associated with a significantly increased risk of minor complications (P less than .001). A history of abdominal surgery was not associated with an increased risk of minor complications. Surgical skill level was not associated with the complication rate.

Cervix Uteri↗
PubMed1980

Pharmacodynamic basis for the interaction of cimetidine with the bone marrow stem cells (CFUS).

A histamine H2-receptor agonist, 4-methylhistamine, triggers the pluripotent stem cells of mouse bone marrow from a noncycling state into the DNA synthetic phase of the cell cycle. The histamine H2-receptor blocking agent cimetidine antagonized the action of 4-methylhistamine. The antagonism was reversed by increasing 4-methylhistamine concentrations. When compared at equimolar concentrations with another antagonist, metiamide, cimetidine was more effective than was metiamide at shifting the concentration-response curve of 4-methylhistamine to the right. The data give pharmacodynamic basis for the interaction of histamine-H2-receptor antagonists with bone marrow cells. They also question the hypothesis that the bone marrow toxicity of metiamide was related to the thiouridine group in its structure and that substitution of a cyanoguanidine group for the thiouridine moiety represents a structural modification that would avoid bone marrow effects of histamine-H2-receptor antagonists. Hence, interaction with progenitor cells, e.g., CFUS may be a property of all histamine-H2-receptor antagonists. Pathophysiologic conditions that increase demand for functional hematopoietic cells may represent situations that make bone marrow growth and differentiation susceptible to inhibition by histamine-H2-receptor antagonists.

Animals↗
PubMed1980

Nature of the erythropoietin-independent response of CFU-S to steroids.

Testosterone given in vivo or in vitro triggers the pluripotent stem cell of bone marrow (CFU-S) into S-phase of the cell cycle. This action of testosterone raises many questions with regard to the cellular mechanisms utilized by testosterone for its cell-cycle effect. The extent to which triggering is coupled to the androgenic activity of this steroid or to the presence of erythropoietin is also of importance. In vitro studies in a system free of serum or plasma, steroid structure activity studies, use of the Tfm mutant system and the application of a unique steroid (batrachotoxin) and one of its antagonists (tetrodotoxin) to the CFU-S system have served to answer some of these questions. Results suggest that the cell cycle action of many steroids is erythropoietin independent, does not utilize androgen binding receptors, and does not utilize cyclase systems. Studies with batrachotoxin suggest that steroids may trigger CFU-S into S-phase by an effect upon ion conductance mechanisms at the level of the cell membrane.

Animals↗
PubMed1977

Mechanism for histamine H2-receptor induced cell-cycle changes in the bone marrow stem cell.

The treatment in vitro of mouse bone marrow cells with 4-methylhistamine triggered the hematopoietic stem cell (CFU-S) from the G0 state into the S-phase of the cell cycle. In contrast, 2-methylhistamine had no such effect. Metiamide antagonized the effects of low concentrations of 4-methylhistamine. Antagonism by metiamide was reversed by high concentrations of 4-methylhistamine. Imidazole, and activator of phosphodiesterase, also suppressed the cell-cycle effects of 4-methylhistamine. The latter findings suggests that cyclic nucleotides may mediate in the stem cell response to 4-methylhistamine. Blocking the metabolism of endogenous histamine with a combination of aminoguanidine and chloroquine also initiated DNA synthesis in the bone marrow stem cell. Metiamide antagonized the effects of the aminoguanidine/chloroquine combination. These experiments associate a histamine H2-receptor with the hematopoietic stem cell. They also suggest that, if available, endogenous histamine can initiate cell-cycle changes in the pluripotent bone marrow stem cell.

Animals↗
PubMed1977

Analysis of receptor mechanisms involved in the hemopoietic effects of androgens: use of the Tfm mutant.

The insensitivity of Tfm mutant mice to androgens is due to a greatly diminished ability to bind 5alpha-dihydrotestosterone to androgen-binding receptors in the cytoplasm of target tissues. Testosterone stimulates hemopoiesis through several mechanisms. The Tfm mutant mouse was used in an attempt to delineate hemopoietic effects of androgens that are mediated by androgen-binding receptors from those that require other cellular mechanisms. Mice of the Tfm mutant and related (androgen-binding) genotypes were treated with multiple doses of 5alpha-dihydrotestosterone (5alpha-DHT). The Tfm mutant was not stimulated to incorporate 59Fe, suggesting that androgen-binding receptors mediate this hemopoietic action of 5alpha-DHT. In contrast, the mutation did not block the ability of a single dose of 5alpha-DHT to increase the absolute number of committed granulocyte/macrophage precursors (CFU-C) in the femurs of mutant mice. The latter finding suggests that androgen-binding receptors are not involved in the mechanisms that lead to amplification of the CFU-C population by 5alpha-DHT. Tfm mutant mice respond to nonandrogenic stimuli of erythropoiesis. These findings emphasize the specificity of the diminished ability of the Tfm mutant mouse to respond erythropoietically to androgen. Accordingly, the Tfm mutant mouse appears to be a useful analytical tool for studying mechanisms underlying the hematopoietic effects of testosterone and related steroids.

Animals↗