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Biomedical subjects

S M Carter

Publications and source records attributed to S M Carter.

35 records · Page 2Linked to original sources
PubMed1996

Placental echolucencies: does their presence influence outcome following genetic amniocentesis?

Women undergoing genetic amniocentesis procedures were evaluated for the presence of ultrasonographic echolucencies within the placenta. Non-calcified sonolucencies < 4 to 5 cm were classified as subchorionic hematomas (SH). Of the 1,000 pregnancies evaluated, 153 (15%) pregnancies manifested SH prior to amniocentesis (study group). The indications for referral were similar in the study and control groups. There were 13 (1.3%) losses: 3 and 10 in the study and control groups, respectively, with no statistical difference in fetal losses between the groups: RR 1.52 (95% confidence interval 0.56-4.14; p = 0.32). Placental sonolucencies < 4 to 5 cm in diameter appear to be incidental ultrasound findings not associated with increased fetal loss following genetic amniocentesis. Complications following invasive prenatal diagnosis cannot be attributed to the presence of these common ultrasound findings.

Adult↗
PubMed1995

Effect of prolonged catecholamine infusion on immunoregulatory function: implications in congestive heart failure.

OBJECTIVES: This study sought to characterize the effects of prolonged catecholamine infusion on immunoregulatory cell traffic and activation. BACKGROUND: Immunoregulation has been shown to be partially controlled by the sympathetic nervous system. Although short-term elevation of catecholamine levels is known to alter immunoregulatory cell traffic and activation, the effects of prolonged heightened sympathetic nervous system activity have not adequately been studied. We believe that the alterations in immune function seen in patients with congestive heart failure are linked to a prolonged elevation of circulating catecholamine levels. METHODS: To characterize the effects of prolonged elevation of catecholamine levels, rats received 4 weeks of constant infusion of epinephrine or norepinephrine through implanted osmotic minipumps. Peripheral and splenic leukocyte subsets, T cell proliferation and interleukin-2 receptor expression were quantified. Antibody production to the novel antigen keyhole limpet hemocyanin was assessed over the 4-week treatment period. RESULTS: Both epinephrine and norepinephrine caused significant splenic atrophy and cardiac hypertrophy; both were blocked by propranolol. Epinephrine induced lymphocytosis; both catecholamines caused an increase in natural killer cells. In the spleen, both epinephrine and norepinephrine led to a dose-dependent decrease in total T cells, suppressor/cytotoxic T cells and natural killer cells and a significant increase in B cells. Epinephrine at the low dose enhanced mitogen-induced proliferation and interleukin-2 receptor expression. Norepinephrine at the low dose appeared to diminish proliferation. Epinephrine tended to inhibit IgG antibody production, whereas norepinephrine had no effect. CONCLUSIONS: The results of our study indicate that prolonged elevation of catecholamine levels alters immune cell proliferation and differentiation. These alterations differ greatly from those induced by short-term stimulation but, for the most part, parallel those found in patients with congestive heart failure. We postulate that the shifts in immunoregulatory cell type and function seen in patients with congestive heart failure are due, in part, to longstanding increases in circulating catecholamine levels and may play an important role in the pathogenesis and progression of disease.

Animals↗
PubMed1993

Gender differentiated receptivity to sexuality education curricula by adolescents.

Teenagers comprise a substantial proportion of the 'at risk' population for sexually transmissible diseases (STDs) and AIDS. They are, also, potentially amenable to the curriculum influences of the high school, suggesting that a high profile needs to be accorded to sexuality education curricula. The variable of receptivity along gender lines to sexuality education programs is explored and reported in this study. An instrument was constructed to measure key constitutive variables in the dimensions of meaning and attitude, and administered to a sample of Western Australian high school students (N = 533). Data were subjected to a two-way ANOVA with sex and school as the dependent variables. It was found that there are differences in receptivity to sexuality education curricula between male and female high school students; that receptivity, irrespective of gender, rises with increasing curriculum provision and with males showing higher gains when compared with females. The findings have implications for policy makers and administrators in providing access to extensive school-based sexuality education curricula.

Adolescent↗
PubMed1991

Measurement of urinary medium chain acyl glycines by gas chromatography--negative ion chemical ionization mass spectrometry.

Medium chain acyl-CoA dehydrogenase (MCAD) deficiency is an inborn error of fatty acid metabolism, which is difficult to diagnose, partly because of its unpredictable clinical presentation. A specific diagnostic marker is an increased excretion of certain medium chain acyl glycines. A sensitive and specific method has been developed for the extraction, derivatization, identification and quantitation of urinary medium chain acyl glycines by gas chromatography-negative ion chemical ionization mass spectrometry (GC-NICIMS). The following series of standard acyl glycines has been synthesized and characterized: hexanoyl, octanoyl, 3-phenylpropionyl and suberyl and their respective isotopomers (using 13C2-glycine; for use as internal standards). The range of excretion of these compounds in normal subjects has been established using this method and increased excretion of acyl glycines, particularly hexanoyl, 3-phenylpropionyl and suberyl was successfully demonstrated in three MCAD deficient subjects from one family.

Acyl-CoA Dehydrogenases↗
PubMed1989

Tachyphylaxis with amrinone therapy: association with sequestration and down-regulation of lymphocyte beta-adrenergic receptors.

STUDY OBJECTIVE: To determine whether intravenous therapy with amrinone changes number, location or function of the beta-adrenergic receptors on lymphocytes. DESIGN: Case series. SETTING: Veterans hospital coronary care unit. PATIENTS: Eleven patients with decompensated class III or IV heart failure. INTERVENTIONS: A bolus of intravenous amrinone followed by a continuous infusion at 10 micrograms/kg.min for 72 hours. MEASUREMENTS AND MAIN RESULTS: At 24 to 36 hours there was a reduction in pulmonary capillary wedge pressure (35%), right atrial pressure (20%), and systemic vascular resistance (25%) with an increase in cardiac output (30%). By 72 hours all these parameters had returned nearly to baseline levels. This partial cardiovascular tolerance to amrinone was accompanied by a 126% increase in the plasma epinephrine, a 182% increase in norepinephrine, a 31% decrease in the number of beta-adrenergic receptors on lymphocytes, and a 36% decrease in isoproterenol-stimulated cyclicadenosine monophosphate on lymphocytes. The number of sequestered receptors doubled during the treatment, and the extent of sequestration correlated well with the extent of receptor down-regulation. CONCLUSIONS: The hemodynamic responses to amrinone had virtually returned to baseline by 72 hours. This tolerance was accompanied by increased plasma catecholamines, and a down-regulation, desensitization, and sequestration of beta-adrenergic receptors on lymphocytes. We suggest that these receptor changes also occur in cardiovascular tissues and may in part account for the tolerance to amrinone.

Aged↗
PubMed1989

Regulation of cardiac beta-adrenergic receptors by captopril. Implications for congestive heart failure.

The interaction of the renin-angiotensin system and the sympathetic nervous system in patients with congestive heart failure is not well understood. We tested the hypothesis that angiotensin-converting enzyme inhibitors can resensitize the beta-adrenergic receptor system. Guinea pigs were given captopril, isoproterenol, or both for 2 weeks. At death, cardiac sarcolemmal and light vesicle fractions and intact mononuclear leukocytes were prepared. Captopril treatment led to an up-regulation of cardiac beta 1- but not mononuclear leukocyte beta 2-adrenergic receptors and an increase in isoproterenol-stimulated adenylate cyclase activity in the heart. Animals treated with isoproterenol developed cardiac hypertrophy, had increased plasma norepinephrine levels, and had a decreased number and responsiveness of both cardiac and mononuclear leukocyte beta-adrenergic receptors. Concomitant treatment with captopril attenuated alterations of heart weight, plasma norepinephrine levels, and cardiac beta-receptor density and function. In contrast to its cardiac effects, captopril treatment did not diminish the down-regulation of mononuclear leukocyte beta 2-adrenergic receptors by isoproterenol. Our data suggest that captopril may resensitize the cardiac but not the mononuclear leukocyte beta-adrenergic receptor-adenylate cyclase system after long-term catecholamine exposure.

Adenylyl Cyclases↗
PubMed1982

Tumor marker production in human bronchial carcinoma xenografts.

A total of 37 human bronchial carcinomas (15 small cell, 10 squamous, six large cell and six adenocarcinomas) have been successfully heterotransplanted into immune-suppressed mice. Monolayer tissue cultures have been established from 23 of the xenograft lines. After contact with tumour cells, supernatant culture medium was analysed by radioimmunoassay for adrenocorticotrophin (ACTH), calcitonin, human chorionic gonadotropin beta subunit (beta HCG) and carcinoembryonic antigen (CEA). Calcitonin production was associated with three (13%) xenograft lines (two small cell, one adenocarcinoma). beta HCG was found in three (13%) lines (one small cell, two large cell anaplastic). CEA was produced in 13 (56.5%) lines (seven small cell, two squamous, one large cell, three adenocarcinomas). ACTH was present in 18 (78.2%) lines (11 small cell, two squamous, two large cell, three adenocarcinomas), but evidence indicates that this hormone is not in all cases produced and secreted by the tumour.

Adenocarcinoma↗
PubMed1981

Human platelet phenolsulphotransferase: separate control of the two forms and activity range in depressive illness.

Human phenolsulphotransferase exists in two forms, one specific for dopamine and tyramine, termed "M" and one for phenol, termed "P". In this study we have shown that these two forms are under separate control by correlating their activities in different individuals using different substrates. There was a highly significant correlation between the activities with dopamine, p-tyramine and 4-hydroxy-3-methoxyphenylglycol, but no significant correlation between the activities with any of these three substrates and that with phenol. Neither age nor sex had any effect on platelet phenolsulphotransferase "M" or "P" activities. Nor was there any significant correlation between platelet monoamine oxidase activity and phenolsulphotransferase "M" or "P" activities. Human platelet phenolsulphotransferase "M" was found to be unstable at temperatures above 35 degree C and it lost substantial activity when stored deep frozen in isotonic saline. However it was stable for up to four months when stored in isotonic sucrose or 10 mmol/l phosphate buffer (pH 7.4). Phenolsulphotransferase "M" amd "P" activities were measured in platelets from depressed patients of a diagnostic type characterized by low output of tyramine-O-sulphate after oral tyramine loading but their enzyme activities were not different from those in two control groups.

Arylsulfotransferase↗
PubMed1980

Decreased urinary output of conjugated tyramine is associated with lifetime vulnerability to depressive illness.

In a group of normal pregnant women whose psychiatric histories were unknown, those with the lowest output of urinary tyramine (free plus conjugated) after an oral tyramine load had a significantly higher lifetime incidence of depressive illness compared with those with the highest output. as none of the women were suffering from depression at the time of tyramine loading, it seems likely that this decreased excretion of tyramine is associated in some way with vulnerability to depressive illness, whether puerperal or nonpuerperal.

Chronic Disease↗
PubMedDate not supplied

Chemotherapy of human tumors in T-lymphocyte-deficient mice.

Human lung, ovarian, colonic, and renal carcinomas have been grown in mice artificially deprived of T-lymphocytes. All grew slowly and were shown to have a human karyotype even after several transplant generations. Their responses to chemotherapy were similar to the expected clinical response with the important exception of hexamethylmelamine which caused complete regression of two lung carcinomas (even when weighing up to 2.5 g at the start of treatment) and a renal carcinoma, while completely inhibiting the growth of an ovarian carcinoma and another lung carcinoma. Measurement of plasma carcinoembryonic antigen levels proved to be of value in assessing drug efficacy.

Altretamine↗
PubMedDate not supplied

The effect of die-spacing on crown retention.

Ten extracted molar teeth were prepared to a standardised complete crown preparation. Five stone dies were constructed for each tooth and coated with zero, two, four, six, and eight layers of a paint-on die-spacer. Crowns were fabricated on each die and the force required for removal from each tooth was measured prior to cementation. The crown elevation and force required for removal were measured after luting with zinc phosphate cement. The force required to remove the crowns before cementation decreased with increasing layers of die-spacer. Following cementation, the mean crown elevation decreased from 547 micrometers (zero layers) to 38 micrometers (eight layers); while the mean removal force increased from 250 N (zero layers) to 375 N (eight layers).

Analysis of Variance↗