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Biomedical subjects

B Jacobson

Publications and source records attributed to B Jacobson.

At least 73 records · Page 4Linked to original sources
PubMed1986

Blood serotonin concentrations and fenfluramine therapy in autistic children.

Whole-blood serotonin concentrations of 31 autistic children, aged 2 1/2 to 16 years, 10 non-autistic retarded children, and 18 children with Down syndrome were measured by a fluorometric method and compared with those of normal children of similar age range. No significant difference in the serotonin concentration per milliliter of whole blood or per 1000 platelets was found between groups for autistic, retarded, or normal children, but the values for those with Down syndrome were significantly lower. A double-blind cross-over study on the effect of fenfluramine versus placebo in seven autistic boys over a period of 8 months demonstrated a significant decrease in blood serotonin levels during the fenfluramine phase in all subjects. Slight improvements were found in short-term auditory memory and some measures of receptive language skills, particularly in children functioning at a high level. There was no significant change in global psychometric measurements of general intelligence during therapy. No adverse clinical effect was observed other than weight loss of 6% in one child. We conclude that fenfluramine may have some selective favorable effects on increasing attention in high-functioning autistic children. Blood serotonin concentration may be followed as an indication of drug compliance during fenfluramine therapy, but does not appear to reflect clinical efficacy.

Adolescent↗
PubMed1985

Pharmacokinetics and distribution of flucloxacillin in pacemaker patients.

The pharmacokinetics of flucloxacillin in plasma and tissue fluid after i.v. infusion of 1 g was analyzed according to an open two-compartment model in 19 patients with bradyarrhythmias (mean age 70.8 years) admitted for implantation or replacement of a permanent pacemaker system. After the first infusion of flucloxacillin (5 min), the distribution phase was rapid (t 1/2 alpha = 0.13 h). The plasma half-life of elimination (t 1/2 beta) was 1.51 h, which is almost twice as long as reported in healthy volunteers. Total plasma clearance (93.1 ml/min) was also lower than is usually found in healthy individuals, due to low renal clearance of flucloxacillin (60.2 ml/min). The total apparent volume of distribution during the beta-phase (Vdarea) was 0.172 l/kg and distribution in the central compartment (Vc) 0.064 1/kg. In each patient plasma protein binding and drug distribution to plasma water, proteins and blood cells in whole blood were determined. Binding in plasma to proteins was 91.0% and distribution to blood cells in whole blood 13.8%. The mean distribution volume of free flucloxacillin during the beta-phase (Vd beta free) was 2.18 1/kg, which exceeds total body water, suggesting possible intracellular distribution and substantial tissue binding. Plasma concentrations of flucloxacillin after the fourth dose (1 g t.i.d.) were very similar to those obtained after the first infusion and those predicted from the single dose kinetics. The concentration of flucloxacillin in fluid from the pacemaker pockets in 5 patients averaged 12.1 micrograms/ml and 9.5 micrograms/ml at 1 and 5 h, respectively, which was more than ten times the MIC-values for Staphylococcus aureus and S. epidermidis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Inhibition of vascular endothelial cell growth and trypsin activity by vitreous.

Vitreous from bovine, human and chick embryo has been found to contain a trypsin inhibitory activity. Chymotrypsin-inhibitory activity was also identified in bovine and chick embryo vitreous. Following either ultrafiltration or Bio Gel P-10 chromatography, these activities appear in fractions having a molecular weight greater than 10000 MW (ultrafiltration) or greater than 13000 MW (P-10 void volume), and are separable from low molecular weight aortic endothelial cell growth inhibitory activity present either in the ultrafiltrate or P-10 retarded volume. Treatment of the trypsin inhibitory fraction with hyaluronidase had no effect on trypsin inhibition, nor did addition of hyaluronic acid inhibit trypsin. Chick embryo vitreous and hyalocyte-conditioned medium were found to contain aortic endothelial cell growth inhibitory activity in both the void volume and retarded volume fractions following Bio Gel P-10 chromatography. Both the 6200 MW bovine vitreous endothelial cell growth inhibitor and the high molecular weight chick embryo vitreous endothelial cell growth inhibitor (greater than 13000 MW) were similar, in that most of the activity did not bind to heparin linked to Sepharose CL-6B.

Animals↗
PubMed1984

Vascular endothelial cell growth inhibitor of normal and pathologic human vitreous.

Normal and pathologic human vitreous have been analyzed for the presence of a low-molecular weight inhibitor of aortic endothelial cell proliferation. Vitreous was subjected to gel chromatography and the material appearing in the retarded volume (less than 13,000 daltons) was tested for its ability to inhibit tritiated thymidine incorporation into DNA by calf aortic endothelial cells. Depending on the sample of vitreous analyzed, one or more fractions showing inhibitory activity were identified in each case.

Adult↗
PubMed1984

Degradation of glycosaminoglycans by extracts of calf vitreous hyalocytes.

The ability of extracts of calf vitreous hyalocytes to catalyze the degradation of glycosaminoglycans was studied by incubation with radioactively labeled substrates. The degradation of the polymeric substrates to lower molecular weight products was assayed by three methods: (1) paper chromatographic separation of low molecular weight, mobile digestion products from undigested, high molecular weight material which remains at or near the origin; (2) loss of the ability of the glycosaminoglycan to be precipitated by cetylpyridinium chloride; (3) gel chromatography to separate low molecular weight digestion products, which appear in the retarded volume, from undegraded, high molecular weight material, which is eluted in the void volume. The acidic pH optimum of the reaction suggests a lysosomal origin of the enzyme activity.

Animals↗
PubMed1984

Identification of sialyl and galactosyl transferase activities in calf vitreous hyalocytes.

Sialyl and galactosyl transferase activities are demonstrated in calf vitreous hyalocytes. For study of sialyl transferase activity, a partially purified vitreous preparation (collagen and hyaluronic acid removed), and bovine submaxillary mucin were treated with an insolubilized neuraminidase before use acceptor of radioactivity from CMP-[3H]-N-acetylneuraminic acid (CMP-[3H]-NAN). For study of galactosyl transferase activity the vitreous preparation was treated first with insolubilized neuraminidase and then with an insolubilized beta-galactosidase before use as acceptor of radioactivity from UDP-[3H]-galactose (UDP-[3H]-gal). Galactosyl transferase requires a divalent metal ion for optimal activity, and the reactions catalyzed by each enzyme are dependent upon pH, time of incubation and concentration of enzyme and/or acceptor.

Animals↗
PubMed1984

Antibiotic prophylaxis in pacemaker surgery--a prospective study.

To evaluate the effect of antibiotic prophylaxis in pacemaker surgery, 100 patients were randomly assigned to a prophylaxis group receiving cloxacillin or to a control group with no antibiotics. Cloxacillin was given intravenously (2 g) 2 hours before operation, followed by 1 g every 6 hours for 2 days and the same dose perorally for 8 more days postoperatively. Adequate plasma concentrations were obtained in all patients. The follow-up time was 1-43 months. The infection rate was 2% (1/50) in the prophylaxis group and 14% (7/50) in the control group (p less than 0.05). The interval from operation to manifest infection was 9-35 days. In the control group the causal microorganism was Staphylococcus aureus in two patients, Staphylococcus epidermidis in two and unknown in three patients. In the only patient with infection in the prophylaxis group, a methicillin-resistant S. epidermidis was isolated. Infection was initially localized to the pacemaker pocket in seven patients, but septicemia developed in one of them and endocarditis in another. In one patient septicemia appeared initially, without local signs of infection. This study suggests that cloxacillin prophylaxis is of value in routine pacemaker surgery.

Aged↗
PubMed1984

Factors influencing the oxidation of cysteamine and other thiols: implications for hyperthermic sensitization and radiation protection.

Some of the factors influencing the oxygen uptake and peroxide formation for cysteamine (MEA) and other thiols in serum-supplemented modified McCoy's 5A, a well-known medium used to cultivate a variety of cells in vitro, have been studied. The oxidation of MEA and cysteine in modified McCoy's 5A has been compared with that in Ham's F-12, MEM, and phosphate-buffered saline. All of the growth media were supplemented with 10% calf serum and 5% fetal calf serum. The rate of oxygen uptake for all of the studied thiols was greatest in McCoy's 5A. The data indicate that this medium may contain more copper than the other preparations. MEA and cysteine were found to be more effective at 0.4 mM at producing peroxide than dithiothreitol (DTT). N-acetylcysteine was the least reactive. The ability to produce peroxide is dependent upon the temperature, the concentration of thiol, the presence of copper ions, and pH of the medium. MEA and other thiol oxidation is inhibited by the copper chelator diethyldithiocarbamate. Catalase also reduces the oxygen uptake for all thiols. This inhibition involves the recycling of peroxide to oxygen. Superoxide dismutase (SOD) was found to stimulate the oxygen uptake in the case of MEA and cysteine, but had little or no effect with DTT and glutathione. The combined presence of SOD and catalase resulted in less inhibition of oxygen uptake than that obtained by catalase alone. Alkaline pH was found to enhance the oxidation of cysteine and MEA. An important observation was the inhibition of MEA oxidation at 0 degrees C and the stimulation at 42 degrees C. The results indicate that many problems may arise when thiols are added to various media. A major consideration is concerned with the production of peroxide, superoxide, and reduced trace metal intermediates. The presence of these intermediates may result in the production of hydroxyl radical intermediates as well as the eventual oxygen depletion from the medium. Oxygen depletion may alter the results of radiation sterilization and carcinogen activation. Radical production will cause cell damage that is temperature dependent. Therefore, careful consideration must be given to changes in oxygen tension when thiols are added to cells growing in complicated growth medium to protect against either chemical or radiation damage.

Catalase↗
PubMed1983

Fast and efficient purification of yeast plasma membranes using cationic silica microbeads.

A fast and efficient procedure for the purification of plasma membranes of Saccharomyces cerevisiae is described. Protoplasts served as starting material. They were coated with cationic silica microbeads. After lysis, the plasma membranes were washed free from debris and cell organelles. This procedure resulted in a high yield (about 85%) of plasma membranes, as judged by measuring vanadate-sensitive ATPase as a plasma membrane marker. The enzyme was enriched 12-fold relative to the homogenate after lysis. Its specific activity was 1.5--2.0 micromol/min per mg protein, the pH optimum was 6.5, and 10 microM vanadate was sufficient to obtain maximum inhibition. Based on the assay of internal markers and electron microscopic studies, we found our preparation essentially free of contamination from other cell organelles.

Adenosine Triphosphatases↗