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Biomedical subjects

J Brown

Publications and source records attributed to J Brown.

At least 775 records · Page 43Linked to original sources
PubMed1988

Experience with potency preservation during radical prostatectomy. Significance of learning curve.

Potency preservation after radical prostatectomy is relatively new. The efficacy of this procedure has not been widely documented. Twenty-four patients with full potency underwent nerve-sparing radical prostatectomy. A total of 12 patients retained potency after surgery. Analysis of data reveals there is a learning curve in doing this procedure, and once the initial learning phase is over good results can be obtained in a select group of patients.

Aged↗
PubMed1988

Tumorigenic human squamous lung cancer cells have defined cell surface carbohydrates that are absent from nontumorigenic cells.

Cells of cloned lines derived from human squamous lung carcinomas spontaneously become heterogeneous with respect to several tumor-associated cell surface carbohydrates such as the sialosyl-Lea oligosaccharide antigen or the recently described oligosaccharide recognized by monoclonal antibody 43-9F. Subclones derived from these cultures are initially homogeneous with respect to the presence or absence of a specific cell surface carbohydrate but gradually revert back to a heterogeneous population. Cells of homogeneous subclones having both the sialosyl-LEa and 43-9F cell surface antigens and other subclones lacking them were injected subcutaneously in nude mice. All clones expressing these tumor-associated cell surface carbohydrates were found to be highly tumorigenic, whereas those lacking them were nontumorigenic or, at most, weakly tumorigenic. Clones having the tumor-associated cell surface carbohydrates were more resistant to cytotoxic attack by purified mouse natural killer cells than those clones lacking these carbohydrates, suggesting that the tumorigenicity of the former clones may be influenced by immunoprotective effects of these novel carbohydrates.

Animals↗
PubMed1988

The risk of leukemia in Seascale from radiation exposure.

An excess of leukemias in children has been observed between 1950 and 1980 in the village of Seascale (population about 3,000) which is situated approximately 3 km to the south of Sellafield nuclear fuel reprocessing plant in West Cumbria, England. Radiation doses from all the main sources of radiation exposure of the population and risks of radiation-induced leukemia have been calculated for children born and living in Seascale during the period of operation of the plant. For the Seascale study population of 1225 children and young persons, followed to age 20 y, or followed until 1980 for those born after 1960, 0.016 radiation-induced leukemias are predicted from the Sellafield discharges. This corresponds to an average risk to children in the population of about one in 75,000. For the four fatal leukemias observed in the study population (0.5 expected from United Kingdom statistics) to be attributed to the operations at Sellafield, the average risk would have to be increased by a factor of about 250, to one in 300. Although there is some uncertainty about the releases from the plant and concentrations of radionuclides in environmental materials in the Sellafield area, particularly for the early years of its operation, the possibility that the doses calculated and the risk coefficients used for radiation-induced leukemia could be so substantially wrong is very unlikely. The number of radiation-induced leukemias from all radiation sources is calculated to be 0.1, which corresponds to a risk of about one in 12,250 for the average child in the study population. About two-thirds of the risk is from natural radiation, 16% from the Sellafield discharges, and nuclear weapons fallout and medical exposure each contribute about 9%. The models used for calculating radiation doses from intakes of radionuclides were based upon those recommended by the International Commission on Radiological Protection (ICRP). This presented a number of difficulties in the assessment, which included the lack of any generally accepted age-related dosimetric models, particularly for bone-seeking radionuclides; limited information on gut transfer factors for radionuclides incorporated in foodstuffs; and no dosimetric models for the fetus. These and other problems identified in the analysis that require more information are discussed.

Air Pollutants, Radioactive↗
PubMed1988

The effect of lithium on the renal response to the dopamine prodrug gludopa in normal man.

1. The effect of oral lithium on the renal response to gamma-L-glutamyl-L-dopa (gludopa, 25 micrograms kg-1 min-1) was investigated in seven normal males. 2. Gludopa at this dose produced an 800-fold increase in urine dopamine excretion. It was natriuretic and suppressed plasma renin activity without altering blood pressure and pulse. 3. Lithium alone increased sodium excretion and stimulated plasma renin activity. However, it abolished the natriuresis produced by gludopa. 4. Gludopa did not significantly affect lithium clearance. 5. This study suggests that lithium interacts with dopamine at the proximal tubule and that the lithium clearance method is not suitable for investigating dopaminergic mechanisms in the kidney.

Adult↗
PubMed1988

Vascular responses to local atrial natriuretic peptide infusion in man.

1. The effect on skin and muscle blood flow of arterial infusion of atrial natriuretic peptide (ANP) directly into the forearm circulation, and on venous tone of direct infusion into a dorsal hand vein, was studied in normal subjects. 2. ANP produced a dose-dependent increase in both skin and muscle blood flow, but at equivalent doses, produced no dilatation of noradrenaline-preconstricted dorsal hand veins. These findings indicate that ANP acting locally, is an arterioselective dilator in the upper limb circulation in normal man. 3. Measurements of ANP in venous plasma during arterial infusion suggest marked clearance of ANP across the forearm vascular bed. Such peripheral clearance may, at least in part, account for the short plasma half-life of this peptide. 4. The lowest dose of ANP infused was calculated to produce plasma levels similar to those found in patients with heart failure. The findings with this dose suggest that, in heart failure, circulating levels of ANP may be within a range capable of influencing peripheral vascular resistance directly.

Adult↗
PubMed1988

Methods used to improve gamete efficiency.

Male factor infertility accounts for a significant percentage of problems in infertile couples. With clinical utilization of the technologies for selection of good-quality spermatozoa from the ejaculate, our ability to successfully treat the severely affected male factor couple has improved. However, it must be remembered that even with current technologies, fertilization success is reduced in these patients but remains above a 50% level. Other factors that can be used in the future to improve on these statistics are being investigated in regard to the in vitro environment for gametes, that is, the type of culture medium, the methods of coincubation of the sperm and egg, and other methods of enhancement of sperm fertilizing potential. However, methods of sperm preparation will achieve improvement in a percentage of these males treated, and can be used to improve fertilization and pregnancy success. It is important to understand the limitations of the zona-free hamster test, but it is also important to use that test as a screening method for sperm handling. By utilizing the SPA to select out the optimal method of sperm preparation, the fertilization and pregnancy outcome can be improved. Overall, the live-birth rate in male factor infertile couples is lower than non-male-factor couples treated by IVF and GIFT. Until more is known about basic spermatozoal function, and the ability to improve that function in affected males, the live-birth rate should not be expected to change substantially.

Cell Separation↗
PubMed1988

Effects of interrupting the renin-angiotensin system on sodium excretion in man.

1. Twelve normal volunteers were studied on 2 separate days, having taken a range of diets providing 50-300 mmol sodium per day for 3 days and having been dehydrated overnight. Each volunteer received a background intravenous infusion of arginine vasopressin (5 x 10(-7) i.u. kg-1 min-1) on both days, and also received 6 mg captopril orally on one day and a placebo tablet on the other. The ensuing changes in arterial pressure, and in urinary solute and solute-free water excretion were recorded. 2. Captopril did not significantly alter arterial pressure. It increased the rate of excretion of sodium but not of potassium, and it did not significantly change urinary osmolality or creatinine clearance. 3. Captopril increased the rate of solute-free water reabsorption and did so in direct proportion to its effect of increasing sodium excretion. 4. A further twelve normal, dehydrated volunteers on free diets were studied on each of 2 days, after taking 500 mg lithium carbonate on the previous evening. On each day, they also received a loading dose and maintenance infusion of inulin. On one day they received 50 mg captopril orally, and, on the other, they received a placebo tablet. The arterial pressure, urinary excretion of electrolytes, and inulin clearance were recorded. 5. Captopril increased the rates of excretion of sodium, lithium and potassium, but there were no significant changes in inulin clearance or arterial pressure. 6. The natriuretic effect of captopril in either group of twelve volunteers was not significantly less in those volunteers who were already excreting more sodium, at least over the range of dietary sodium loading to which the volunteers were subjected. 7. Six normal volunteers were studied on a further 2 days, having taken a diet supplying 30 mmol sodium per day for 3 days and being dehydrated overnight. Each volunteer received a background intravenous infusion of arginine vasopressin (5 x 10(-7) i.u. kg-1 min-1) on both days and also received an intravenous infusion of saralasin acetate (50 ng kg-1 min-1) plus carrier on one day and carrier alone on the other. The ensuing changes in arterial pressure, and in urinary solute and solute-free water excretion were recorded. 8. There was a small but significant fall in systolic arterial pressure during the infusion of saralasin.(ABSTRACT TRUNCATED AT 400 WORDS)

Arginine Vasopressin↗
PubMed1988

Comparison of virulence factors and R plasmids of Salmonella spp. isolated from healthy and ill swine.

The antibiotic resistance and virulence profiles of Salmonella spp. isolated from healthy (group 1) and ill (group 2) swine were compared. Parameters studied included colicin and siderophore production; mannose-sensitive hemagglutination of erythrocytes; resistance to the lethal effect of serum complement; resistance to antibiotics; and the transmissibility of these characteristics to recipient organisms. Group 1 (19 isolates) had 14 serotypes, and group 2 (20 isolates) had 2 serotypes. Isolates from group 2 were resistant to more antibiotics and had a greater ability to hemagglutinate erythrocytes and transfer R plasmids to recipient organisms, but a lesser ability to produce siderophore than group 1. All 39 isolates resisted the lethal effects of serum complement. Colicin was produced by 1 of 19 from group 1 and 0 of 20 from group 2. A donor Escherichia coli isolated from a pig with enteritis transferred R plasmids to 62% of group 1 and 0% of group 2 Salmonella spp. when they were used as recipient organisms. A transconjugant from the mating of donor E. coli to a group 1 Salmonella spp. was further able to pass an R plasmid to recipient E. coli and salmonellae. Plasmid isolation from group 1 yielded 1 of 19 strains with a 56-megadalton plasmid, while 20 of 20 strains from group 2 contained three to five plasmids from 2.4 to 60 megadaltons in size.

Animals↗
PubMed1988

Immunoneutralization of somatostatin and neurotensin: effect on gastric acid secretion.

Cell lines producing monoclonal antibodies to somatostatin and neurotensin, designated S-10 and NT-C5, respectively, have recently been generated. The purpose of the present immunoneutralization study in urethan-anesthetized gastric fistula rats is 1) to examine the ability of these antibodies to block the inhibitory effect of their target peptides on meal-stimulated gastric acid secretion and 2) to use these antibodies as probes to determine whether somatostatin and/or neurotensin are involved in the inhibition of gastric acid secretion produced by intraduodenal, intra-ileal, and intracolonic fat infusions. The results demonstrate that both S-10 and NT-C5 successfully bound exogenous somatostatin and neurotensin in vivo. S-10 but not NT-C5 prevented the inhibition of gastric acid secretion produced by intraduodenal fat. NT-C5 but not S-10 prevented the inhibition of gastric acid secretion produced by intra-ileal fat. Neither S-10 nor NT-C5 prevented the inhibition of gastric acid secretion produced by intracolonic fat. We conclude that somatostatin is associated with proximal and neurotensin with distal small bowel intestinal fat-induced inhibition of gastric acid secretion.

Animals↗
PubMed1988

A preliminary report of long-term elimination of detectable mutans streptococci in man.

Application of an antimicrobial varnish to the teeth of 33 adult volunteers resulted in the elimination of detectable mutans streptococci from the saliva of 21 of them for a mean period of 34.6 weeks (range, 4 to 89 weeks) without additional treatment. The mean number of applications of varnish required for elimination was 3.14 (range, 1 to 5). Extensive examination of 10 subjects made free of mutans streptococci on the basis of saliva examination revealed no detectable mutans streptococci in their dental plaque. In 14 of the subjects in whom mutans streptococci were eliminated, they subsequently re-appeared after a mean period of 22.7 weeks (range, 4 to 71 weeks). Four out of the five recurrences that were treated were eliminated with only one additional varnish application. The treatment failed to provide long-term elimination of detectable mutans streptococci in 12 of the 33 treated subjects. No serious adverse reactions were observed in any of the treated subjects. The results indicate that it is possible to eliminate mutans streptococci from man in a safe and effective manner.

Adult↗
PubMed1988

Menstrual migraine: a double-blind trial of percutaneous estradiol.

The present study investigated whether administration of percutaneous estradiol for the 7 days encompassing menstruation (the paramenstruum) would be effective in alleviating menstrual migraine. The study was a double-blind cross-over placebo comparison of percutaneous estradiol in gel form. Twenty-two women who suffered from regular recurring menstrual migraine were studied during 2 assessment menstrual cycles, 4 treatment cycles (2 of estradiol gel, 2 of placebo gel), and 1 follow-up (no treatment) cycle. Women completed daily records of the occurrence and severity of migraine and medication used. Eighteen women completed the study. There was a significant reduction in the frequency of migraine in the paramenstruum and in the amount of medication taken during use of percutaneous estradiol. Women expressed a significant preference for continuation of therapy with percutaneous estradiol.

Administration, Cutaneous↗
PubMed1988

Respiratory cryptosporidiosis in chickens.

In order to better characterize spontaneous respiratory cryptosporidiosis in chickens, a retrospective examination of histopathology reports from the Georgia Poultry Laboratories for an 18-mo period (4/1/86 to 9/30/87) was made; 12 cases were found. Collected data were analyzed and certain epidemiologic and histologic features were identified. Eleven of the 12 cases involved broiler type chickens. The ages of chickens with respiratory cryptosporidiosis were evenly distributed between 17 and 52 days of age. The infected birds were always clinically ill. Viruses or bacteria or both often accompanied respiratory Cryptosporidium sp. infections. Histologic lesions (including those of ciliary-adherent bacteria) are described. As the inflammatory response in infected organs became progressively nonpurulent (lymphocytes and plasma cells predominate), numbers of Cryptosporidium diminished. Cytologic preparations were useful for making diagnoses of respiratory cryptosporidiosis in chickens. Identification of epidemiologic features of respiratory cryptosporidiosis, and improved ability to make accurate and prompt diagnoses of Cryptosporidium sp. infection, are vital for a more complete understanding of the impact of this disease on poultry health.

Animals↗