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Biomedical subjects

J Stewart

Publications and source records attributed to J Stewart.

At least 415 records · Page 23Linked to original sources
PubMed1987

Flow cytometric quantitation of the c-myc oncoprotein in archival neoplastic biopsies of the colon.

The c-myc oncogene encoded protein product, p62c-myc, was assayed simultaneously with DNA in populations of individual nuclei extracted from archival biopsies of colonic neoplasia. Both the protein and DNA were assayed fluorimetrically using flow cytometry with a synthetic peptide induced monoclonal antibody (MYC 1-6E10) for the protein and propidium iodide for DNA. The nuclear p62c-myc levels increased progressively from normal mucosa through polyps to carcinomas. However, there was a trend for the more poorly differentiated carcinomas to exhibit lower levels than moderately and well-differentiated tumours, p = 0.085. These results agree with those published previously with the same antibody using Western blotting for protein extracted from fresh frozen tissue and immunocytochemical assessment. Furthermore, flow cytometry is able to effect discriminations between subsets in heterogeneous populations using DNA as a second parameter which Western blot bulk studies cannot.

Biopsy↗
PubMed1987

Left ventricular full-thickness cardiomyoplasty with pericardial neoendocardium: experimental development of a surgical procedure.

Cardiomyoplasty, a surgical procedure using stimulated skeletal muscle graft to replace or repair damaged myocardium, has been successfully performed in experimental animals and clinical patients. Whenever feasible, endocardium of the damaged myocardial segment is retained and partial-thickness cardiomyoplasty should be carried out. However, if this procedure were to be applied to enlarge a hypoplastic ventricle or to maintain normal dimensions of the ventricular cavity in some repairs in adults, full-thickness replacement of the ventricular wall with contractile skeletal muscle mass would be required. To develop such a technique, several canine experiments were carried out. In 7 dogs, "simple full-thickness cardiomyoplasty" was performed by using a latissimus dorsi muscle graft to repair a full-thickness left ventricular wall defect. We found it was difficult to obtain adequate hemostasis between the nonscarred myocardial tissue and the skeletal muscle graft, and excessive suturing to obtain hemostasis resulted in strangulation of the muscle grafts. The skeletal muscle-blood interface in the left ventricle was found to be highly thrombogenic. The perioperative hemorrhage and the risk of muscle graft strangulation by excessive sutures were avoided by using a pericardial patch as neoendocardium in 5 dogs that underwent similar full-thickness cardiomyoplasty procedures. Although the pericardial neoendocardium was not fully antithrombogenic in this canine model, endothelialization of the endocardium occurred within several weeks after operation. Thus, when combined with an implantable synchronized burst stimulator, this technique may in the future provide an effective "full-thickness dynamic cardiomyoplasty" to enlarge the ventricles and augment myocardial function in select patients.

Animals↗
PubMed1987

Activation and expression of endogenous pain control mechanisms in rats given repeated nociceptive tests under the influence of naloxone.

In six experiments, it was found that animals administered the opiate receptor blocker naloxone prior to either hot-plate or tail-flick nociceptive tests developed reduced sensitivity to pain relative to animals tested under saline. The naloxone-induced analgesia was most pronounced following administration of 10 mg/kg naloxone, with weaker effects occurring at 0.5 and 2 mg/kg. The effect manifested itself in tests using mild (48.5 degrees hot-plate tests), but not more severe (52 degrees or 56 degrees hot-plate tests), intensities of nociceptive stimulation. The analgesia observed in animals tested under naloxone arose in part from the attenuation of the habituation of stress-induced analgesia produced by the novelty of the test apparatus, and in part from exposure to nociceptive stimulation. It appears to be mediated by a nonopiate mechanism; naloxone enhanced the analgesia produced by exposure to brief, continuous shock, but blocked the analgesia elicited by prolonged, intermittent shock (see Lewis, Cannon, & Liebeskind, 1980). We also found that administration of naloxone prior to nociceptive testing enhanced the development of conditioned autoanalgesia (as assessed by nociceptive tests conducted under saline), and that the enhanced conditioned autoanalgesia summated with the analgesic effect of morphine. The results are discussed in terms of the activation and expression of both opiate and nonopiate pain suppression mechanisms; their implications for models of situation specific morphine analgesic tolerance are discussed.

Animals↗
PubMed1987

Morphine attenuation of conditioned autoanalgesia: implications for theories of situation-specific tolerance to morphine analgesia.

The effect of morphine administration on the development of conditioned autoanalgesia was investigated in four experiments. Animals were administered either morphine or saline and then either exposed or not exposed to nociceptive stimulation. In Experiments 1, 2, and 4 the nociceptive stimulus to which animals were exposed was electric footshock, and in Experiment 3 it was thermal stimulation produced by exposure to a hot plate. It was found that morphine administration attenuated the development of conditioned autoanalgesia produced by exposure to 1-mA shock for 45 s when tests for conditioned autoanalgesia were conducted when animals were under the influence of saline or morphine (Experiments 1 and 2). Morphine also attenuated the conditioned autoanalgesia arising from exposure to 1-mA shock for 15 s, but only when the conditions for the development and expression of conditioned autoanalgesia were made optimal (Experiment 4). Morphine failed to block conditioning when animals were exposed to 2.5-mA shock for 180 s (Experiment 1). Morphine also attenuated conditioned autoanalgesia when animals were exposed to thermal stimulation (Experiment 3), with the degree of attenuation increasing as a function of the intensity of the nociceptive stimulus. The results are discussed in terms of their implications for theories of situation-specific tolerance to the analgesic effect of morphine.

Analgesia↗
PubMed1987

The diets of pregnant and post-pregnant women in different social groups in London and Edinburgh: energy, protein, fat and fibre.

1. Dietary records were obtained twice in pregnancy and once post-partum from 265 women from all social classes in London and Edinburgh. 2. The London women always had higher mean energy, protein, fat and fibre intakes. Significant between-region differences emerged. 3. Some between-social classes differences occurred, but were not consistently significant. 4. All mean energy and fibre intakes were lower, and protein and fat intakes were higher, than current recommendations. 5. Of lactating women 15% claimed to be dieting. 6. The percentage dietary energy derived from fat varied from 36 (in a dieting group) to 42.

Adolescent↗
PubMed1987

HLA class I and II, interferon, interleukin 2, and the interleukin 2 receptor expression on labial biopsy specimens from patients with Sjögren's syndrome.

Labial biopsy specimens from eight patients with primary Sjögren's syndrome (SS), 10 patients with secondary SS, and three healthy controls were studied with monoclonal antibodies identifying HLA class I and class II antigens; interferon-alpha, beta, and gamma; interleukin 2 (IL2); and the IL2 receptor (Tac) among others. In the normal biopsy specimens there was evidence of HLA class I and, to a lesser extent, class II antigens in both ducts and acini, though this was much less marked than in the Sjögren's biopsy specimens. Interferon-gamma staining, but not interferon-alpha or beta, was also considerably enhanced in the biopsy specimens from the patients with Sjögren's syndrome. These data support the view that in Sjögren's syndrome the release of interferon-gamma may be involved in the induction of class II determinants. Our observations were broadly similar in both primary and secondary Sjögren's syndrome except that patients with primary Sjögren's syndrome tended to have more diffusely scattered T lymphocytes.

Aged↗
PubMed1987

Expression of c-myc oncogene in coeliac disease.

A monoclonal antibody, produced by peptide immunisation was used to detect the distribution of p62c/myc by immunohistology in normal and coeliac small intestinal mucosa. The effect of gluten in four treated coeliac patients was investigated by taking serial jejunal biopsy specimens for six hours after a 10 g oral gluten challenge. There was a progressive increase in p62c/myc staining intensity in the villus enterocytes extending to the crypts, which accompanied the classical morphological changes occurring in the mucosa.

Antibodies, Monoclonal↗
PubMed1987

Life-threatening dysrhythmias in varicella myocarditis.

Varicella myocarditis is an unusual complication of a common childhood disease. Two patients with life-threatening dysrhythmias and circulatory failure are reported. One patient required permanent pacemaker implantation for acquired complete heart block, not previously described with varicella infection. Previously reported cases of varicella myocarditis are reviewed.

Arrhythmias, Cardiac↗
PubMed1987

Effect of pretreatment with 3-methylcholanthrene and several phenolic antioxidants on glutathione S-transferase activity in various tissues of female Sprague-Dawley rats.

1. Treatment of female Sprague-Dawley rats with 3-methylcholanthrene, butylated hydroxyanisole, ethoxyquin, propyl gallate or methylcholanthrene plus butylated hydroxyanisole was undertaken to determine the effects on glutathione S-transferase activity in liver, small intestine, lung and kidney. 2. A significant increase in hepatic transferase activity was found following all treatments, except after propyl gallate, when 1-chloro-2,4-dinitrobenzene was used as substrate. 3. When 1,2-dichloro-4-nitrobenzene was the substrate, only butylated hydroxyanisole and the combination of butylated hydroxyanisole and methylcholanthrene resulted in a significant increase. 4. In the extra-hepatic tissues using 1-chloro-2,4-dinitrobenzene as a substrate, all treatments caused an increase in transferase activity in the lung; ethoxyquin and combined methylcholanthrene plus butylated hydroxyanisole increased this activity in the kidney, whereas only the combined methylcholanthrene plus butylated hydroxyanisole increased activity in the small intestine. 5. All treatments caused a notable decrease in the composite Km and had varying effects on the composite Vmax of hepatic transferase activity.

Animals↗
PubMed1987

Comparison of the glucuronidation ability of liver microsomes from rats treated with 3-methylcholanthrene or phenolic antioxidants.

1. UDP-glucuronyltransferase activity was studied in hepatic microsomal preparations isolated from female Sprague-Dawley rats treated with either 3-methylcholanthrene, butylated hydroxyanisole, propyl gallate, ethoxyquin or a combination of 3-methylcholanthrene and butylated hydroxyanisole. 2. The substrates p-nitrophenol, 1-naphthol and phenolphthalein were used. With p-nitrophenol all treatments, except propyl gallate, caused a significant increase in activity over the control value; the combined treatment of 3-methylcholanthrene and butylated hydroxyanisole gave an additive response when compared to each treatment used singly. With 1-naphthol as substrate, 3-methylcholanthrene and 3-methylcholanthrene + butylated hydroxyanisole caused 8-fold increases in activity compared to the 2-3 fold increased caused by the other treatments. When phenolphthalein was used, all treatments increased activity to the same extent. 3. When the assays were repeated with various concentrations of each substrate, the results revealed that, except where phenolphthalein was used, distinguishable differences in the activity of each microsomal preparation were discernible, the most significant being the bimodal response of each preparation to low and high concentrations of p-nitrophenol.

Animals↗
PubMed1987

Identification of pre- and postsynaptic bradykinin receptor sites in the vas deferens: evidence for different structural prerequisites.

The effect of bradykinin on the neuroeffector junction of the isolated rat vas deferens was studied in tissues stimulated transmurally at a frequency of 0.15 Hz. Bradykinin caused two distinct and independent actions: it potentiated the magnitude of the muscular response to the electrically driven twitches and, in addition, contracted the smooth muscle generating an increased muscular tone. The former action is referred to as the neurogenic or presynaptic effect, whereas the latter effect is called the musculotropic or postjunctional action. The neurogenic effect was abolished by tetrodotoxin or tissue denervation either by cold storage or chemical sympathectomy after 6-hydroxydopamine administration. However, these procedures did not significantly modify the musculotropic potency of bradykinin. Both actions of the peptide are receptor-mediated, as minor structural modifications in the amino acid sequence caused significant changes in biological potency. In addition, the peptide analog, [Thi5,8-D-Phe7]-bradykinin, behaved as an agonist at the presynaptic site but as an antagonist at the muscular site. The most potent peptide analog to produce the neurogenic effect was Met-Lys-bradykinin followed by Lys-bradykinin and [Tyr8]-bradykinin. In contrast, the potency of these peptide analogs acting at the postsynaptic site was about the same. des Arg9 bradykinin and des Arg9-[Leu8]-bradykinin were inactive at the pre- and postjunctional site. The neurogenic action of bradykinin was not mimicked by angiotensin II, neurotensin, substance P or vasopressin.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

In Nigeria. A study to identify the knowledge and misconceptions of primary school pupils about tropical diseases.

"Since health knowledge is a prerequisite of any health action, health education is seen as an essential component of any disease control programme. However for health education to be effective and relevant the prior knowledge held by the learners must be assessed and information so obtained used in the planning and implementation of the health education programme."

Attitude to Health↗
PubMed1986

Pseudo-obstruction.

Explore the source record for details and available documents.

Colonic Diseases↗
PubMed1986

Digital averaging to facilitate two-dimensional echocardiographic measurements.

A problem in quantitative two-dimensional echocardiography is myocardial dropout of still frame images. This study was designed to evaluate the ability of digital averaging to overcome myocardial dropout without distorting quantitative measurements. Forty-one percent of 80 digitally averaged images were thought to be improved by five independent observers, whereas 7% showed some deterioration. Measurements obtained from processed images were statistically identical (r greater than or equal to 0.9) to those from three arithmetically averaged, unprocessed images in 60 patients. Digital averaging can improve image quality without measurement distortion and should facilitate two-dimensional echocardiographic quantitation.

Analog-Digital Conversion↗
PubMed1986

Detection of sister chromatid exchanges induced by volatile genotoxicants.

To test the recently developed method of exposing cells to volatile compounds, phytohemagglutinin-stimulated human peripheral lymphocyte cultures were exposed to gaseous methyl bromide, ethylene oxide, and propylene oxide, as well as diesel exhaust. The cultures were placed in sterile dialysis tubing and inserted into enclosed flasks containing additional culture medium. The test compounds (in gaseous state) were diluted with air and bubbled through the flasks for various lengths of time. The cells were then washed and incubated for a total of 75 h. The harvest was performed according to established procedures, and second-division cells were scored for induction of sister chromatid exchanges (SCEs). The SCE frequency was more than doubled in the cultures treated with ethylene oxide and propylene oxide; methyl bromide also induced SCEs. Cultures treated with diesel exhaust showed an increase in the SCE frequency in cells from two of four donors tested. These results further substantiate the use of this method for detecting the induction of SCEs by airborne genotoxins.

Cells, Cultured↗