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S Culbert

Publications and source records attributed to S Culbert.

22 records · Page 2Linked to original sources
PubMed1974

Cholinergic modification of glucose-induced biphasic insulin release in vitro.

An in vitro system for perifusion of rat pancreatic islets has been utilized to define the effects of cholinergic agents on the dynamics of insulin release. In the absence of glucose the effects of either acetylcholine or acetyl-beta-methylcholine were minimal at concentrations up to 10(-5) mM. In the presence of low glucose concentration (2.4 mM), both of the muscarinic agents produced dose-dependent biphasic insulin release. Under these conditions significant insulin release was observed over both phases at concentrations of the muscarinic agents as low as 10(-8) mM. Further, the dose response curves relating muscarinic concentration to the total amount of insulin released in each of the two phases showed lack of parallelism between the curves. Nicotinic acid in concentrations up to 10(-5) mM had no effect on insulin release in the presence of 2.4 mM glucose. When the glucose concentration was increased to 16.4 mM, the effects of the muscarinic agents were significantly less than those observed in the presence of 2.4 mM glucose. This held true whether the effect was defined as absolute increment due to the muscarinic agent or as percentage of enhancement. Atropine inhibited insulin release induced by both acetylcholine and by 16.4 mM glucose. These data indicate that cholinergic stimulation can play a significant role in modifying insulin release patterns.

Acetylcholine↗
PubMedDate not supplied

Antimicrobial therapy of febrile children with malignancies and possible sepsis.

A prospective study of 100 pediatric patients (2 months to 17 years of age) who had malignancies and fever was conducted. Gentamicin or netilmicin and a beta-lactam antibiotic were administered as initial empiric treatment. Before therapy profound granulocytopenia (fewer than 500 polymorphonuclear leukocytes/microliter) was present in 66% of children and persisted to the end of therapy in 42% of children. Of the 40 children with microbiologically documented infections, 38 (95%) responded to therapy. The aminoglycoside dosing regimen of 2 mg/kg/dose intravenously over 60 minutes every 6 hours produced antibiotic concentrations in serum of 5.8 +/- 0.3 microgram/ml at the end of the infusion in the netilmicin group and 1.5 +/- 0.1 microgram/ml 6 hours after the infusion and of 6.2 +/- 0.2 and 0.9 +/- 0.1 microgram/ml for the two time periods in the gentamicin group. The serum half-lives, volumes of distribution and the total body clearance rates were comparable for netilmicin and gentamicin. No accumulation of netilmicin or gentamicin was noted. Seven patients had renal compromise, five before institution of antibiotic therapy and two while on therapy. Four episodes of ototoxicity were not related to antibiotic therapy. Superinfection occurred in five children. The combination of either gentamicin or netilmicin with a beta-lactam antibiotic produced excellent results for episodes of fever in neutropenic children with cancer. In children with severe underlying disease and/or granulocytopenia, antibiotic combinations have achieved an optimal efficacy. Future emphasis should be placed on prevention, immunoregulation and nonbacterial pathogens.

Adolescent↗