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Biomedical subjects

A S Gordon

Publications and source records attributed to A S Gordon.

At least 73 records · Page 4Linked to original sources
PubMed1987

Influence of Alginate on Attachment of Vibrio spp. to Stainless Steel Surfaces in Seawater.

The influence of alginate on the attachment of Vibrio alginolyticus and Vibrio pelagius biovar II to stainless steel was investigated. When the bacteria were in stationary phase, alginate decreased the number of attached bacteria in the case of each Vibrio sp. In contrast, when V. pelagius biovar II was grown on alginate and harvested in log phase, attachment was increased. This effect may be due to nutrient availability at the surface or to receptors on the bacterial surface which interact with alginate adsorbed to the metal.

Journal Article↗
PubMed1986

Phenylhydrazine-induced leukocytosis in the rat.

Rats were injected with phenylhydrazine (PHZ) for periods of up to 6 months, during which time a marked leukocytosis was induced. The highest leukocyte counts occurred within 4-5 days following injection. An initial injection of 4 mg/100 gm body weight evoked a mean total leukocyte count of 129 X 10(3) cells/microliter. Successive weekly injections of 2 mg/100 gm resulted in a mean total leukocyte count of 70 X 10(3) cells/microliter compared to a mean total leukocyte count of 12.5 X 10(3) cells/microliter in saline-injected rats. Lymphocytes and monocytes accounted for approximately 75% of the total cell counts in both the PHZ-treated and control rats. The presence of increased numbers of mononuclear cells was confirmed by Percoll gradient separation and by phase-contrast microscopy. Although a leukocytosis was evident when using the automated Coulter electronic cell counter, it was not discernible when blood samples were counted manually in a hemocytometer by light microscopy. Histological examination of the thymus, lymph nodes, and spleen of the PHZ-treated rats indicated that lymphocytes and monocytes were mobilized from these sites. Lymphocyte depletion was evident, and germinal centers were found in all these lymphoid organs, indicating that PHZ induced a lymphopoietic response. A possible autoimmune etiology for PHZ-induced red blood cell destruction is discussed.

Animals↗
PubMed1986

Surgery of snoring.

Habitual, loud snoring is common in the adult population, and may be the only symptom of the more serious Obstructive Sleep Apnoea syndrome. We report here our results of uvulo-palato-pharyngo-plasty (UPPP), with or without nasal surgery, for snoring. Quantitative grading of the severity of the snoring shows that all patients were cured of symptomatic snoring, but that snoring was not altogether abolished in all patients.

Adult↗
PubMed1986

nu 1, a Mr 43,000 component of postsynaptic membranes, is a protein kinase.

Acetylcholine receptor-enriched membranes from the electric organ of Torpedo californica show a major band at Mr 43,000 on NaDodSO4/polyacrylamide gels. This band is composed of three polypeptides: nu 1, nu 2, and nu 3. Polypeptide nu 1 has been found to be localized exclusively at the innervated face of the electrocyte and at the neuromuscular junction in rat muscle. We show here that monoclonal antibody to nu 1 precipitates a radioactive Mr 43,000 polypeptide from detergent-solubilized extracts of Torpedo membranes covalently labeled with periodate-oxidized [alpha-32P]ATP. The monoclonal antibody also precipitates protein kinase activity from neutralized pH 11 extracts of the acetylcholine receptor-rich membranes. These data suggest that nu 1 is a postsynaptic membrane protein kinase.

Adenosine Triphosphate↗
PubMed1986

Ethanol regulation of adenosine receptor-stimulated cAMP levels in a clonal neural cell line: an in vitro model of cellular tolerance to ethanol.

The acute and chronic neurologic effects of ethanol appear to be due to its interaction with neural cell membranes. Chronic exposure to ethanol induces changes in the membrane that lead to tolerance to the effects of ethanol. However, the actual membrane changes that account for tolerance to ethanol are not understood. We have developed a model cell culture system, using NG108-15 neuroblastoma-glioma hybrid cells, to study cellular tolerance to ethanol. We have found that adenosine receptor-stimulated cAMP levels increased markedly upon acute exposure to ethanol. However, the cells became tolerant to ethanol, since chronically treated cells required ethanol to maintain normal adenosine-stimulated cAMP levels. Moreover, the cells appeared to be dependent on ethanol, as evidenced by reduced adenosine-stimulated cAMP levels in the absence of ethanol. Recovery occurred after ethanol was withdrawn. These cellular changes appear to parallel the clinical events of acute ethanol intoxication, tolerance, and dependence.

Animals↗
PubMed1986

Denitrification in marl and peat sediments in the Florida everglades.

The potential for denitrification in marl and peat sediments in the Shark River Slough in the Everglades National Park was determined by the acetylene blockage assay. The influence of nitrate concentration on denitrification rate and N(2)O yield from added nitrate was examined. The effects of added glucose and phosphate and of temperature on the denitrification potential were determined. The sediments readily denitrified added nitrate. N(2)O was released from the sediments both with and without added acetylene. The marl sediments had higher rates than the peat on every date sampled. Denitrification was nitrate limited; however, the yields of N(2)O amounted to only 10 to 34% of the added nitrate when 100 muM nitrate was added. On the basis of measured increases in ammonium concentration, it appears that the balance of added nitrate may be converted to ammonium in the marl sediment. The sediment temperature at the time of sampling greatly influenced the denitrification potential (15-fold rate change) at the marl site, indicating that either the number or the specific activity of the denitrifiers changed in response to temperature fluctuations (9 to 25 degrees C) in the sediment. It is apparent from this study that denitrification in Everglades sediments is not an effective means of removing excess nitrogen which may be introduced as nitrate into the ecosystem with supply water from the South Florida watershed and that sporadic addition of nitrate-rich water may lead to nitrous oxide release from these wetlands.

Journal Article↗
PubMed1986

Onset of adolescent drinking: a longitudinal study of intrapersonal and interpersonal antecedents.

This study investigated several models for exploring the interrelationships of domains of personality, peer, and family factors and their effect on initiation into alcohol use. Three hundred eighteen black and white high school students were administered questionnaires when they were in the ninth and tenth grades (T1) and again two years later when the students were in the eleventh and twelfth grades (T2). Only those students who had never used alcohol at T1 were included in this study. The results supported an independent model: Each of the domains of T1 personality, peer, and family factors, with control on the other domains, had a direct effect on T2 initiation into alcohol use. The interactions of peer variables with personality and family variables were examined. The findings indicated that risk factors stemming from the peer group were ameliorated by protective personality and family factors.

Adolescent↗
PubMed1986

Effects of the hormone erythropoietin in milk on erythropoiesis in neonatal rats.

Erythropoiesis was stimulated in 2- to 5-day-old normal neonatal rats nursed by phlebotomized mothers, and in 12-day-old hypertransfused neonatal suckled for 4 days by a twice-bled mother. Erythropoietic stimulation was evidenced as increases in hemoglobin levels and numbers of peripheral reticulocytes in the 2- to 5-day-olds, and by a higher 48-hour RBC-59Fe incorporation in the hypertransfused than in control 12-day-olds. The reticulocyte maturation curve was shifted to the left in 14-day-old transfused rats suckled by an anemic mother, in 14-day-old normal rats suckled by an anemic mother, and in 12-day-old transfused neonates fed cow milk to which erythropoietin (Ep) had been added. The oral administration of cow milk containing Ep to 10-day-old normal neonates induced a reticulocytosis. One-day-old rats suckled by mothers bled 72 h prior to delivery exhibited significant amounts of Ep in their plasma as compared to nondetectable levels in 1-day-old control rats of normal mothers. Decreases in relative percentages of nucleated erythrocytes were noted in spleens of hypertransfused 12-day-old neonates nursed by anemic mothers, in spleens of hypertransfused 12-day-old injected with Ep, and in spleens of 14-day-old normal rats suckled by an anemic mother. Nucleated erythrocyte numbers were reduced in both spleen and marrow of 12-day-old anemic neonates. The data suggest that: Ep is transmitted to neonatal rats via maternal milk, and in the process of gastrointestinal tract absorption, escapes inactivation, thereby stimulating erythropoiesis in these animals; Ep acts on already differentiated erythroid cells by influencing their rate of maturation.

Anemia↗
PubMed1985

The effects of interferon on murine erythropoiesis.

The effects of interferon (IF) on erythropoietin (Ep) action and production were studied in mice. In comparison to control animals, Ep action in exhypoxic, polycythemic mice was significantly decreased (p less than 0.05) following two low dose injections of IF (2.9-3.5 X 10(4) units). In addition, renal Ep production in normal intact mice was also significantly decreased (p less than 0.01) following a single injection of IF (5.4-6.3 X 10(4) units) and hypoxic exposure.

Animals↗
PubMed1985

Evidence for a hepatic-renal antagonism in the production of hepatic erythropoietin in a phenylhydrazine-induced compensated hemolytic state in the rat.

A compensated hemolytic state was induced in rats by injection of phenylhydrazine (PHZ) over a 6-week period. The liver and kidney were perfused to determine the levels and time of appearance of a hepatic erythropoietic factor (HEF) which induces the production of hepatic erythropoietin (Ep) and its antagonist, a renal inhibitory factor (RIF). Erythropoietin assays on the perfusates have been previously reported. The amount of HEF in perfusates recovered from the livers of the PHZ-treated rats was significantly higher during the 4th to 5th weeks of treatment, coinciding with the time of increased liver production of Ep. During the 6th week of PHZ treatment, the titer of RIF in perfusates recovered from the kidney was markedly increased and the HEF titer was decreased to near the control level, suggesting inhibitory action of RIF on HEF synthesis and/or effect. These findings indicate that an HEF/RIF control mechanism regulates hepatic Ep production in this compensated hemolytic condition.

Animals↗
PubMed1985

Erythropoietin production by macrophages in the regenerating liver.

The site of erythropoietin (Ep) production and/or storage in the rat liver was determined. A guinea pig anti-Ep was produced against purified rat Ep (64,096 +/- 4j064 IU/mg). This antibody was found to be highly specific using rocket immunoelectrophoresis, Ouchterlony gel diffusion methods, and immunoprecipitin reactions as well as Ep neutralization tests (capable of completely neutralizing up to 2,000 IU Ep/mg). This anti-Ep was labeled with either fluorescein for light microscopic study or ferritin for electron microscopy. Kupffer cells showed varying degrees of labeling after hepatectomy alone or hepatectomy combined with nephrectomy and/or hypoxia. Greatest labeling was seen in Kupffer cells of rats that were nephrectomized 48 hr posthepatectomy and kept at ambient pressure. No labeling of hepatocytes or vascular and bile duct endothelium was noted.

Animals↗
PubMed1985

Atypical facial pain: a retrospective study.

Among the most challenging patients seen for evaluation by a health care practitioner are those suffering from the atypical facial pain syndrome. They have almost inevitably been subjected to extensive treatment which either has had no effect on the symptoms or has aggravated them. This article reports a retrospective study of thirty-four randomly selected cases of atypical facial pain that have been seen by a multidisciplinary pain group.

Adult↗
PubMed1985

Stability of personality during adolescence and its relationship to stage of drug use.

The purpose of this study was to examine how stability of personality, measured at two points during adolescence, relates to adolescents' stage of drug use, measured at the second point in time. The subjects were 704 black and white high school freshmen and sophomores who participated again two years later. Results indicated that the earlier measures of personality were significantly associated with the later measures of personality, which in turn were associated with the adolescents' stage of drug use. In addition, the adolescents' personality attributes showed a fair amount of stability over the two-year span of the study.

Achievement↗
PubMed1985

An evaluation of factors associated with proliferative diabetic retinopathy.

Many individual factors have been related to development of proliferative diabetic retinopathy. To evaluate possible interactions among these, a constellation of variables were studied in 22 patients with long duration of insulin-dependent diabetes mellitus for greater than 25 years, with minimal background diabetic retinopathy, and compared to 27 patients with insulin-dependent diabetes mellitus for a variable duration, but with bilateral proliferative retinopathy. The patients were compatible in age at onset of diabetes (12 +/- 2 in proliferative retinopathy group vs 12 +/- 1 yr in the background retinopathy group). Following initial standard statistical analyses, data were further analysed using Logistic Regression Analysis. In the proliferative retinopathy group males were more prevalent (2.9:1), and patients were treated with larger insulin doses (0.86 +/- 0.07 vs 0.59 +/- 0.04 U/Kg B.W., p less than 0.001). Systemic hypertension and neuropathy were more prevalent (p less than 0.02 and less than 0.004 respectively), and diastolic blood pressure was higher (87 +/- 3 vs 75 +/- 2, p less than 0.01). In the same group diet was higher in carbohydrate and the ratio of polyunsaturated to saturated fats was lower (p less than 0.03, less than 0.05 respectively). HbA1 was higher (0.127 +/- 0.004 vs 0.110 +/- 0.004%, p less than 0.004), but the mean of all available plasma glucose values was not different. Impaired renal function expressed by higher BUN, serum creatinine, and urinary protein and lower creatinine clearance was observed. Nerve conduction parameters were more significantly impaired and plasma triglycerides were higher (1.74 +/- 0.2 vs 0.85 +/- 0.1 mmol/l, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Interaction of ethanol with neural cells in culture: a model of intoxication, tolerance and withdrawal.

The interaction of ethanol with the nervous system produces acute intoxication, tolerance and withdrawal phenomena. Additionally, there are several alcohol-related neurological disorders which develop in alcoholic patients. Current evidence suggests that ethanol produces some of these changes by altering the structure and function of neural membranes. Therefore, neurotransmitter receptors and receptor-dependent molecular events in the nervous system may be highly sensitive to ethanol. The murine neuroblastoma X glioma hybrid cell line NG108-15 was used to study the acute and chronic interactions of ethanol with intact cells. Ethanol acutely inhibited opiate receptor binding, but after chronic exposure the cells exhibited an apparent adaptive increase in the number of opiate binding sites; this was reversible when ethanol was withdrawn. High levels of ethanol (200 mM) increased opiate binding after 18-24 hours; lower concentrations (25-50 mM) produced similar changes after two weeks. This model system has great potential for exploring the cellular and molecular mechanisms which underlie ethanol intoxication, tolerance and withdrawal.

Adaptation, Physiological↗
PubMed1984

Irreversible inhibition of phospholipid methylation and protein carboxymethylation does not alter acetylcholine receptor function in muscle cells.

The role of methyltransferase (MT) reactions in acetylcholine (ACh)-evoked depolarization and contraction in primary chick myotubes was determined by using a mixture of erythro-9-(2-hydroxy-3-nonyl) adenine, homocysteine thiolactone, and adenosine which together inhibit the activity of MT. Carboxy-MT and lipid-MT activities were inhibited irreversibly by 91 and 100%, respectively. ACh-induced muscle contraction was also inhibited within 10 min after application of the inhibitor mixture. However, in contrast to permanent inhibition of MT activities, inhibition of acetylcholine receptor (AChR)-dependent muscle contraction was reversible. Moreover, physiological studies showed that the inhibitor mixture had no effect on resting membrane potential or ACh-induced depolarization or desensitization. These results suggest that AChR function is not altered by methylation inhibitors and that changes in AChR-mediated contraction are not due to inhibition of MT activities.

Acetylcholine↗