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Biomedical subjects

S Abraham

Publications and source records attributed to S Abraham.

At least 127 records · Page 7Linked to original sources
PubMed1992

Extracellular matrix in aged human ciliary body: an immunoelectron microscope study.

Tissue from nine human eyes (ages 52-78 yr) was used to investigate the fine structural distribution of collagens I-VI and laminin in the ciliary body using the immunogold antibody labeling technique. The anterior segments of the specimens were normal, and the eyes were removed in treatment of choroidal melanoma. The basement membranes of the ciliary epithelium contained collagens I, III, and IV. Laminin was in greater concentration in the outer part of the nonpigmented epithelial basement membrane, and the distribution suggested a washout effect. The zonular apparatus labeled intensely with laminin. In contrast, laminin was not present in the basement membrane of the myocytes in the ciliary body. These cells were sheathed in a basement membrane that contained types I, III, and IV collagen. Plaque-like structures of slightly different morphology (a, filamentous; b, granular; c, amorphous) were found in the tendinous insertions, and subtypes a and b were strongly labeled with laminin. The basement membranes of the vessels contained types I and IV collagen, but laminin labeling was inconclusive. The major finding was that the lamina densa in the basement membranes of various sites labeled for collagens I, III, and IV. Striated collagen fibrils in the stroma were labeled for types I and III. Collagen subtypes V and VI were not identified in significant quantity in any of the regions examined.

Aged↗
PubMed1991

Metabolism of meadowfoam oil fatty acids in mice.

Meadowfoam oil is unusual because over 95% of the fatty acids are 20- and 22-carbon aliphatic acids with cis double bonds located principally at the 5- and/or 13-position. Since little information is available on the metabolism of the 5c-20:1 and 5c,13c-22:2 fatty acids, an exploratory study in mice was conducted to investigate the metabolism of purified samples of the free fatty acids isolated from meadowfoam oil, and to determine the effect of meadowfoam oil on weight gain and tissue lipid composition. Mice fed diets containing 5% by wt of the purified 5c-20:1 or 5c,13c-22:2 for 6 days exhibited no apparent physiological problems. Total liver lipids from mice fed the purified fatty acid diets contained mean values of 2.0% 5c-20:1 and 2.1% 5c,13c-22:2; total heart lipids contained 1.7% 5c-20:1 and 10.7% 5c,13c-22:2. Liver total phospholipids from mice fed a 5% meadowfoam oil diet for 19 wk contained 1.4% 5c-20:1 and 1.9% 5c,13c-22:2. There was no evidence of desaturation, elongation or retroconversion. Weight gain for mice fed the meadowfoam oil diet for 19 wk was similar to mice fed corn oil, and was higher than for mice fed hydrogenated cottonseed oil. Considering the high 5c-20:1 and 5c,13c-22:2 content of the diets, the percentages of these fatty acids in mouse tissue lipids from both the short- and long-term studies were low. Weight gain was surprisingly good since the meadowfoam oil diet was essential fatty acid-deficient. Results of this initial investigation suggest that the 5c-20:1 and 5c,13c-22:2 fatty acids were utilized primarily for energy.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Antiarrhythmic properties of tedisamil (KC8857), a putative transient outward K+ current blocker.

1. Rats were used to evaluate the antiarrhythmic properties of tedisamil, a novel agent with the electrophysiological properties of a Class III antiarrhythmic drug. Tedisamil was tested against coronary artery occlusion-induced arrhythmias in conscious animals. 2. The actions of tedisamil on the ECG, as well as responses to electrical stimulation, were compared with those on the configuration of epicardial intracellular action potentials recorded in vivo. 3. Tedisamil (1-4 mg kg-1, i.v.) caused bradycardia, elevated blood pressure and dose-dependently reduced ventricular fibrillation (VF) induced by occlusion of the left anterior descending coronary artery. Other ischaemia-associated arrhythmias were not so well suppressed. Antiarrhythmic activity was greatest when the tedisamil-induced bradycardia was prevented by electrically-pacing the left ventricle. 4. Tedisamil dose-dependently lengthened the effective refractory period and prevented electrically-induced VF. In vivo, tedisamil (0.5-4 mg kg-1, i.v.) prolonged the duration of epicardial intracellular action potentials by up to 400%. 5. Results showed that tedisamil possessed antifibrillatory actions in rats that were related to Class III electrophysiological actions as revealed by electrical stimulation and electrophysiological analyses.

Action Potentials↗
PubMed1991

Attenuation of mammary duct development by menhaden oil in BALB/c mice.

The predominant polyunsaturated fatty acids of the n-6 family found in corn oil (CO) are crucial for normal mammary duct formation when fed to animals. However, as shown here, not all polyunsaturated fatty acids are equally effective in stimulating mammary gland development. The n-3 fatty acids in a 10% menhaden oil (MO) diet fed to mice effectively reduced both the diameter and the length of the growing mammary ducts. Previously, we demonstrated a similar reduction in duct growth by feeding a 10% fat diet high in those saturated fats found in hydrogenated cotton seed oil. The inhibited rate of duct maturation caused by hydrogenated cotton seed oil was reversed when the mice were allowed to mature on a diet containing n-6 fatty acids prior to feeding the saturated fat diet. The addition of 1% CO to a 9% hydrogenated cotton seed oil diet fed to immature mice was also sufficient to restore duct growth. Mice fed menhaden oil diets, on the other hand, continued to show impaired ductal growth well into adulthood. Examination of the ovaries from MO-fed mice as compared with CO-fed mice revealed significantly fewer corpora lutea. When exogenous progesterone was given to MO-fed mice, ductal growth was partially restored, but not to the extent seen in mice fed corn oil diets. Investigation of the fatty acid contents of livers of these mice revealed reduced amounts of arachidonate (20:4) in MO-fed mice when compared with CO-fed animals. The addition of 1% CO to the 9% MO diets did not alter the arachidonate content, indicating a block in the conversion of linoleate (18:2) to 20:4 by the n-3 fatty acids. Hence, dietary n-6 fatty acids are essential for normal mammary ductal development when fed prior to maturation. Although saturated rats are ineffective, n-3 fatty acids can partially substitute for the required n-6 fatty acids in both ductal and ovarian development.

Animals↗
PubMed1990

Recovery after childbirth: a preliminary prospective study.

This prospective study examined the time for 93 women to cease to feel discomfort in their perineal areas after the births of their first babies. Sixty-two of the women had experienced a spontaneous delivery that did not require forceps assistance. In 58 patients, an episiotomy was performed. Of the 35 women in whom an episiotomy was not performed, 24 women required sutures and only four women did not suffer any perineal damage. The median time for perineal comfort in general (including walking and sitting) was one month (range, zero to six months); 20% of women took more than two months to achieve general perineal comfort. For comfort during sexual intercourse, the median time was three months (range, one to more than 12 months); 20% of women took longer than six months to achieve comfort during sexual intercourse. Factors that were associated with discomfort for longer than the median time were delivery by forceps; spontaneous vaginal (not perineal) tears; and, in the three to four days after the birth, oedema and the breakdown of muscle or skin sutures. There was no significant difference in these times between patients who did not undergo an episiotomy and those who underwent an episiotomy without a forceps delivery.

Adolescent↗
PubMed1990

Deduced sequence of the bovine coronavirus spike protein and identification of the internal proteolytic cleavage site.

The sequence of the spike (also called peplomer or E2) protein gene of the Mebus strain of bovine coronavirus (BCV) was obtained from cDNA clones of genomic RNA. The gene sequence predicts a 150,825 mol wt apoprotein of 1363 amino acids having an N-terminal hydrophobic signal sequence of 17 amino acids, 19 potential N-linked glycosylation sites, a hydrophobic anchor sequence of approximately 17 amino acids near the C terminus, and a hydrophilic cysteine-rich C terminus of 35 amino acids. An internal Lys-Arg-Arg-Ser-Arg-Arg sequence predicts a protease cleavage site between amino acids 768 and 769 that would separate the S apoprotein into S1 and S2 segments of 85690 and 65153 mol wt, respectively. Amino terminal amino acid sequencing of the virion-derived gp 100 spike subunit confirmed the location of the predicted cleavage site, and established that gp 120 and gp 100 are the glycosylated virion forms of the S1 and S2 subunits, respectively. Sequence comparisons between BCV and the antigenically related mouse hepatitis coronavirus revealed more sequence divergence in the putative knob region of the spike protein (S1) than in the stem region (S2).

Amino Acid Sequence↗
PubMed1990

Sequence and expression analysis of potential nonstructural proteins of 4.9, 4.8, 12.7, and 9.5 kDa encoded between the spike and membrane protein genes of the bovine coronavirus.

The nucleotide sequence between the spike and membrane protein genes in the bovine coronavirus (BCV) genome was determined by sequencing cDNA clones of the genome, and open reading frames potentially encoding proteins of 4.9, 4.8, 12.7, and 9.5 kDa, in that order, were identified. The 4.9- and 4.8-kDa proteins appear to be vestiges of an 11-kDa protein for which a single nucleotide deletion event in the central part of the gene gave rise to a stop codon. The consensus CYAAAC sequence precedes the 4.9-, 12.7-, and 9.5-kDa ORFs and predicts that transcription will start from each of these sites. Northern analyses using sequence-specific probes and oligo(dT)-selected RNA demonstrated that the predicted transcripts are made, and that these correspond to mRNAs 4, 5, and 5-1. BCV mRNA 4 appears to be a counterpart to mouse hepatitis virus (MHV) mRNA 4 which, in the MHV JHM strain, encodes the putative 15.2-kDa nonstructural protein. BCV mRNAs 5 and 5-1 appear to be used for the synthesis of the 12.7- and 9.5-kDa proteins, respectively, which demonstrates a pattern of expression strikingly different from that utilized by MHV. MHV makes its homologs of the 12.7- and 9.5-kDa proteins from the single mRNA 5. In vitro translation analyses demonstrated that the BCV 9.5-kDa protein, unlike its MHV counterpart, is poorly made from downstream initiation of translation. Thus, from a comparison between BCV and MHV we find evolutionary evidence for the importance of the CYAAAC sequence in regulating coronavirus transcription.

Amino Acid Sequence↗
PubMed1990

Should ovulation be induced in women recovering from an eating disorder or who are compulsive exercisers?

The eating and exercise history of women with secondary amenorrhea and failure of ovulation using CC was studied in 14 consecutive women on a GnRH-a program. All had a history of an eating or exercise disorder. At the time of the interview, 7 women continued to have an eating or exercise disorder. There were 15 pregnancies (12 women) with 12 live births, of which 4 weighed less than 2,500 g. Infertility specialists should inquire routinely about a woman's body weight and eating and exercise behaviors, and consider treatment for these before prescribing drugs to induce ovulation.

Adult↗
PubMed1990

Teaching nutrition to medical students: a community-based problem-solving approach.

This paper presents a community-based problem-solving educational programme which aims at teaching medical and other health science students the importance of nutrition and its application. Through community surveys students assess the nutritional status of children under five using different anthropometric methods. They understand the cultural beliefs and customs related to food fads and the reasons for them. They also acquire the skill to educate the community using the information gathered. They use epidemiological methods such as case control study to find associations between malnutrition and other causative factors. Feedback from students has been positive and evaluation of students' knowledge before and after the programme has shown significant improvement.

Community Medicine↗
PubMed1990

Structure and orientation of expressed bovine coronavirus hemagglutinin-esterase protein.

The sequence of the hemagglutinin-esterase (HE) gene for the Mebus strain of bovine coronavirus was obtained from cDNA clones, and its deduced product is a 47,700-kilodalton apoprotein of 424 amino acids. Expression of the HE protein in vitro in the presence of microsomes revealed N-terminal signal peptide cleavage and C-terminal anchorage but not disulfide-linked dimerization. Dimerization was observed only after expression in vivo, during which HE was also transported to the cell surface.

Amino Acid Sequence↗
PubMed1990

Interactions between peripheral-type benzodiazepine receptor ligands and an activator of voltage-operated calcium channels.

The effects of the peripheral-type benzodiapine receptor (PBR) ligands Ro 5-4864 and PK 11195 were studied in the spontaneously beating guinea pig atrium and in a model for myocardial ischemia in the rat. In the former, Bay K 8644 produced positive chronotropic and inotropic responses; intracarotid administration of this agonist (5 or 10 micrograms kg-1) to anesthetized rats elicited a transient increase in mean arterial blood pressure accompanied by alterations in the ECG pattern. Ro 5-4864 and PK 11195 (10 microM) completely blocked the positive chronotropic effect of Bay K 8644 in the atrium, PK 11209, a structural analog of PK 11195 with a low affinity for PBR, was inactive, and the central benzodiazepine receptor ligand clonazepam had a marginal effect. Ro 5-4864 potentiated whereas PK 11195 inhibited the myocardial ischemia produced by Bay K 8644 in the rat. Furthermore, PK 11195 blocked the combined response to Bay K 8644 and Ro 5-4864. Addition of Ro 5-4864 (10 microM) to the organ bath potentiated the inotropic effect of Bay K 8644 in the atria; PK 11195 at the same concentration inhibited this effect. Clonazepam and PK 11209 were both inactive in this regard. Nifedipine, a potent calcium channel antagonist, completely blocked the inotropic and chronotropic responses to Bay K 8644. PK 11195 and Ro 5-4864 did not affect this action. These findings strongly suggest that there is a functional association between PBR and voltage-operated calcium channels in the guinea pig atrium and rat cardiovascular system.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗