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S Cohen

Publications and source records attributed to S Cohen.

At least 865 records · Page 48Linked to original sources
PubMed1982

Gentamicin-resistant staphylococci as hospital flora: epidemiology and resistance plasmids.

In 1979, gentamicin-resistant (Gmr) Staphylococcus aureus was recovered from the clinical specimens of 22 epidemiologically unrelated hospitalized patients; 78% of the patients evaluated were also colonized with Gmr coagulase-negative staphylococci. Endonuclease fingerprinting was used to compare the Gmr plasmids within pairs of isolates of S. aureus and coagulase-negative staphylococci recovered from nine patients. Plasmids differed between pairs but were concordant within four pairs. Thus, in vivo interspecific plasmid transfer, although infrequent, may be important in the sporadic occurrence of Gmr S. aureus. To define the epidemiology of endemic Gmr coagulase-negative staphylococci, culture surveys were performed over two years. Gmr coagulase-negative staphylococci were acquired by 80% of the infants in a special-care nursery that previously had an outbreak of Gmr S. aureus. Among adult inpatients, a 48% colonization rate was related to prior exposure to antibiotics. In contrast, no colonization was found in outpatients or antepartum mothers.

Adult↗
PubMed1982

Treatment of neovascular senile maculopathy at the foveal capillary free zone with red krypton laser.

Sixty-eight eyes with neovascular senile maculopathy involving the capillary free zone that were assigned randomly for red krypton laser photocoagulation were followed for two years and compared to 55 eyes with the same disease that were not treated. In the majority of the studied eyes there was a decline of visual acuity during the follow-up period. However, an increase in visual acuity was encountered in one third of treated eyes, but no increase in the untreated eyes. The extent of visual acuity deterioration was greater in the nontreated than in the treated eyes. Eyes that were treated when visual acuity was between 6/9-6/60 generally belonged to a better final visual acuity group than those eyes that were treated when visual acuity was less than 6/60. The technique of red krypton laser photocoagulation is described, the rationale for this treatment is discussed, and the results of the treatment are evaluated.

Aged↗
PubMed1982

Structural and phenotypic varieties of gentamicin resistance plasmids in hospital strains of Staphylococcus aureus and coagulase-negative staphylococci.

We previously described a neonatal nursery epidemic of infections caused by a single strain of Staphylococcus aureus bearing a gentamicin resistance plasmid (Vogel et al., Antimicrob. Agents Chemother. 13:466-472, 1978). The same plasmid was present in two isolates of Staphylococcus epidermidis from the patients in this nursery and was transferable interspecifically from either S. aureus or S. epidermidis. During the ensuing 3 years, in the absence of further epidemics, we collected 162 gentamicin-resistant strains of S. aureus and coagulase-negative staphylococci from patients distributed throughout our hospital. Gentamicin resistance plasmids obtained from 41 representative S. aureus and coagulase-negative staphylococcal strains differed as determined by phenotypic and molecular analyses from the plasmid in the neonatal nursery epidemic. Nevertheless, these plasmids were structurally related to each other and to the plasmid of the original epidemic. Our results suggest an evolutionary relationship among these plasmids and support the hypothesis of a genetic reservoir of gentamicin resistance in coagulase-negative staphylococci transferable to S. aureus.

Coagulase↗
PubMed1982

Electrically coupled intrinsic responses of feline lower esophageal sphincter.

Intraluminal pressures and serosal myoelectric activity were recorded simultaneously from the esophagus, lower esophageal sphincter (LES), and stomach of chloralose-anesthetized cats. The LES demonstrated intermittent spike activity basally without slow waves and was distinct from esophagus and fundus. LES spike activity was not correlated with basal sphincter pressure. Dose-dependent increases in both spikes and pressure occurred with bethanechol, phenylephrine, or pentagastrin. Increased spike activity preceded the onset of the pressure rise and peaked during the rise in pressure. Changes in LES pressure and spike activity following these agents were correlated closely (r = 0.92, P less than 0.01). Atropine and isoproterenol inhibited pressure and spike activity similarly. Intrinsic reflexes to endogenous stimuli gave parallel spike and pressure changes. Distal esophageal acidification produced an increase in LES pressure that was correlated with increased spike activity. LES spike activity and pressure were inhibited similarly by antral distension or gastric acidification. Dissection of the distal esophagus from the diaphragm or bilateral cervical vagotomy had no effect on either LES spike activity or pressure. These studies indicate that a) LES myoelectric activity consists of spike discharges that are not correlated to resting pressure, b) abrupt changes in sphincter pressure following either intrinsic reflexes or neurohormonal agents are closely associated with similar changes in spike activity, and c) spike activity and sphincter pressure are intrinsic to the LES.

Animals↗
PubMed1982

Characterization of opiate-mediated responses of the feline ileum and ileocecal sphincter.

Although opioid peptides have been demonstrated immunohistochemically in the feline intestine, the action of these peptides is unknown. The aims of this study were: (a) to determine the distal ileal and ileocecal sphincter (ICS) responses to morphine sulfate (MS), methionine enkephalin (ME) and leucine enkephalin (LE); (b) to determine the mechanism by which exogenous opiates mediate these responses; (c) to determine the type of receptor involved in mediating these responses and (d) to ascertain whether endogenous opiate-mediated responses may be vagally induced. The ICS responded to all three opiate agonists with tonic and phasic contractions, the latter being associated with increased spike activity. The ED(max) for ICS pressure response was 1 mug/kg for ME, 5 mug/kg for LE, and 150 mug/kg for MS. The distal ileum responded with increased spike activity and phasic contractions. The ED(max) for the ileal motility index response was 1.0 x 10(-1) mug/kg for ME, 1 mug/kg for LE, and 150 mug/kg for MS. Thus, both sites demonstrated similar dose-response relationships, both responding to at least 100 times lower doses of enkephalins than MS. The ICS contraction preceded ileal contractions. The ileal and ICS response was not antagonized by atropine, hexamethonium, phentolamine, propranolol, cinanserin, or tetrodotoxin. Naloxone, 600 mug/kg, antagonized the response to the enkephalins while 10 mug/kg antagonized the response to MS. Higher doses of the specific-receptor agonist SKF 10047 and kappa-receptor agonist ketocyclazocine were required before a contractile response was elicited. Electrical stimulation of the cervical vagus induced ICS contraction and a fall in blood pressure. The ICS contractile response but not the blood pressure response was inhibited by naloxone 1 mg/kg. These data indicate: (a) tonic and phasic ICS contraction followed by ileal contraction may be mediated through delta-type opiate receptors located in the muscle membrane and (b) opiate-mediated ICS contraction may be induced during vagal stimulation.

Animals↗
PubMed1982

Steroid production in testicular tissue of the European eel.

Testicular tissue of normal and hCG-stimulated European eels was incubated in vitro with tritiated progesterone or androstenedione as substrates. The following compounds were isolated and identified: 5 beta-androstane-3,17-dione; 17 beta-hydroxy-5 beta-androstan-3-one; androst-4-ene-3,11,17-trione (adrenosterone); 11 beta-hydroxyandrost-4-ene-3,17-dione; 11 beta-hydroxytestosterone; 3 alpha,11 beta-dihydroxy-5 beta-androstan-17-one, and an additional steroid for which the oxidation product was identified as 5 beta-androstene-3,11,17-trione. Four of these steroids have not been hitherto identified in gonadal tissue of any vertebrate. The pattern of steroid production in this tissue is unique for its 5 beta-reduction, for the appearance of adrenosterone as a major metabolite, and for the lack of production of 11-ketotestosterone, which is a regular metabolite of gonadal tissue of teleosts. Thus, it appears that steroid metabolism in the eel testis deviates considerably from the known pattern of steroid production in gonads of other vertebrates.

Androgens↗
PubMed1982

The role of opiate receptors and cholinergic neurons in the gastrocolonic response.

The aim of this study was to characterize the mechanism of the gastrocolonic response to eating in healthy human volunteers. A bipolar clip electrode recorded spike activity from the distal colon. A rapid increase in colonic spike activity occurred after eating a 1000-cal meal (16.1 +/- 2.8 spike potentials/10 min, p less than 0.001). The intravenous infusion of atropine inhibited the increase in postprandial colonic motility. Intragastric administration of procaine, a local anesthetic also inhibited the gastrocolonic response to eating. After sham feeding a modified 1000-cal meal, there was no increase in the gastrocolonic response. Morphine stimulated colonic spike activity (55.3 +/- 15.1 spike potentials/10 min, p less than 0.001). Naloxone (40 microgram/kg . h) completely inhibited morphine stimulation of the colon. Naloxone also inhibited the postprandial gastrocolonic response, but did not inhibit neostigmine stimulation of colonic motility. These data suggest: (1) the gastrocolonic response is mediated by afferent neural receptors in the gastroduodenal mucosa, (2) there is no cephalic phase in the gastrocolonic response to eating, and (3) efferent cholinergic neurons and opiate receptors are both necessary for the gastrocolonic response.

Adult↗
PubMed1982

Clinical aspects of autonomic nerve dysfunction of the gut.

Autonomic dysfunction leads to a variety of clinical disorders involving all parts of the gut. These neural disorders are distinct from the four other recognised categories of disorders involving myogenic function, myoelectric activity, hormonal regulation and abnormal humoral factors. Criteria for establishing that a disorder has a neurogenic aetiology vary in different diseases. Absence of a neural mediated response with intact muscle function has been the major criterion used in most studies. Neural mediated responses of peristalsis, sphincteric relaxation and intestinal contraction following distension or feeding are the major parameters of assessment. Abnormalities in neural function have been demonstrated in achalasia, symptomatic diffuse oesophageal spasm, diabetes mellitus, amyloidosis, scleroderma and chronic idiopathic intestinal pseudoobstruction. The anatomical site and type of gut neurological disorder varies in each condition. Morphological studies have been helpful in demonstrating specific intranuclear inclusion bodies in some pseudoobstruction patients, and vagal and ganglionic lesions in achalasia. Intact muscle ad myoelectric function as well as normal responsiveness to drugs acting directly upon muscle may be established by morphological study. Advancement in basic technology should provide a rewarding area for future study of the pathogenesis and treatment of the gut neurological disorders.

Amyloidosis↗
PubMed1982

Circulating immune complexes in Plasmodium knowlesi infected Kra, and merozoite vaccinated Rhesus monkeys.

The presence of circulating soluble immune complexes that bind the C1q component of complement has been determined in the sera of two monkey species showing different degrees of clinical immunity to Plasmodium knowlesi infection. Material binding C1q was found in the serum of both primarily infected Kra monkeys and post-vaccinated immune Rhesus monkeys following the onset of parasitaemia. The complexes then disappeared from the circulation of Kra monkeys despite continuing low-grade parasitaemia, but in Rhesus monkeys C1q binding material remained detectable for up to 3 weeks after apparent elimination of parasites. The ability of complexes to bind C1q was removed by reduction and alkylation and binding material was absorbed by staphylococcal protein A suggesting the presence of Ig. Further analysis of the binding material is required to fully establish its constitution and possible immunoregulatory function at different stages of infection in the two monkey species.

Animals↗