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Biomedical subjects

A Cohen

Publications and source records attributed to A Cohen.

At least 739 records · Page 41Linked to original sources
PubMed1985

Role of anaerobic spore-forming bacteria in the acidogenesis of glucose: changes induced by discontinuous or low-rate feed supply.

A mineral salts medium containing 1% (w/v) glucose providing carbon-limited growth conditions was subjected to anaerobic acidogenesis by mixed populations of bacteria in chemostat cultures. The formation of butyrate was shown to be dependent on the presence of saccharolytic anaerobic sporeformers in the acid-forming population. By the use of pasteurized activated sludge as an inoculum a culture was obtained consisting solely of anaerobic sporeformers that gave rise to the formation of butyrate, acetate, hydrogen and carbon dioxide as the main fermentation products. No formation of propionate could be detected. In this culture, the role of sporulation was investigated by applying periods of starvation and a single-step lowering of dilution rate (shift-down). In an experiment using a mineral salts medium supplemented with 1% (w/v) glucose and 0.5% (w/v) casein hydrolysate formation of refractile forespores as well as cell lysis could be demonstrated after 6 h starvation. In mixed cultures, initially inoculated with non-pasteurized activated sludge, a regular interruption of feed supply for 1 h per day resulted in selection of non-sporulating anaerobes. The fermentation pattern changed to a production of propionate and acetate, with a concomitant reduction of gas production. Similar results were obtained with shift-down in dilution rate. A relative increase of propionate-forming bacteria was accomplished in a continuous culture experiment with regular two times 2-h periods of starvation per day. The propionate-forming microbial population consisted predominantly of curved rods, tentatively identified as Selenomonas sp.

Acetates↗
PubMed1985

The integrated and free states of Streptomyces griseus plasmid pSG1.

A 16.6-kb plasmid-pSG1-was isolated from Streptomyces griseus following transformation of protoplasts with unrelated plasmids. Southern hybridization experiments with radioactive probes prepared from pSG1 fragments and immobilized S. griseus DNA fragments indicated that the plasmid was present in the progenitor strain, in an integrated state. In the pSG1+ isolates plasmid sequences existed both as integrated sequences and as free plasmids. The integrated state of maintenance persisted in strains which have been cured of the free plasmid. The junction site on the plasmid was located on a 0.5-kb EcoRI-SalI fragment. The chromosomal integration site was demonstrated to be the same in all strains derived from S. griseus NRRL3851. The occurrence of both states of plasmid maintenance in the same clones indicates that an integrated pSG1 sequence does not interfere with free plasmid replication and partition. It suggests that the establishment of the free state may involve a replicative excision of pSG1 from the S. griseus chromosome.

Base Sequence↗
PubMed1985

A microbiological comparison of a povidone-iodine lubricating gel and a control as catheter lubricants.

A randomized, controlled study tested the value of a povidone-iodine (PVP-I) lubricant ('Betadine' lubricating gel), in preventing microbial contamination of bladder urine during catheterization. Urine samples, for culture, were obtained by suprapubic aspiration both before passage, and after removal 15 min later, of a no. 16 Foley catheter coated with the test lubricant or with a control preparation ('K-Y' lubricating jelly). Each treatment group included 10 men and five women. Swab cultures of the anterior urethra, taken immediately before catheterization, demonstrated substantial urethral contamination. Thirteen test subjects and 15 controls qualified for the efficacy analysis and all 30 took part in the safety evaluation. Before catheterization, mean colony counts per 5 ml urine numbered 0.3 in the (PVP-I) treated group and 0.4 among controls. After catheter passage, the mean counts were respectively, 3.6 and 69.6 per 5 ml. Thus, catheters coated with PVP-I lubricating gel transported significantly fewer (P less than 0.03) viable contaminants to bladder urine than those covered with 'K-Y' jelly. The organisms most frequently identified in urethral swabs and pre-study midstream clean-catch specimens also predominated in post-catheterization urine, but their incidence was considerably lower among the PVP-I treated subjects than among controls. Lubricity, cohesiveness and adhesiveness were more satisfactory in the test group than in the control series. No adverse reactions occurred and both preparations, as well as the mechanical procedures, were well tolerated. The findings demonstrated the efficacy of the PVP-I lubricant in preventing transfer of viable urethral organisms to the bladder during catheterization.

Adult↗
PubMed1985

Psychology in health risk messages for workers.

The content, style, and mode of company communications directed to workers regarding job hazards and health risks are frequently based only on concerns for technical accuracy and legal liability. These considerations as shaping factors in informational messages do not ensure worker understanding and responsiveness. Moreover, the uncertainty of health threats posed by many workplace chemical and physical agents, and the delayed, insidious disorders they may portend, present formidable obstacles in this regard. This report describes guidelines that attempt to overcome these difficulties, with specific reference to printed forms of informational material. The guidelines are based on concepts from the cognitive and social psychology literature, with additional input from experts in those fields as well as representatives from management and labor who have responsibilities for worker health education in their respective organizations. Selected guidelines are presented and critiques are offered of samples of hazard information materials directed to workers in light of the guidelines' prescriptions. Field trials are planned as a follow-up.

Accident Prevention↗
PubMed1985

Disordered drinking in developing spontaneously hypertensive rats.

Eating and drinking in spontaneously hypertensive (SHR) and Wistar-Kyoto (WKY) rats were measured at 5-17 wk of life. The SHR drank significantly more water in 24 h than WKY as early as wk 9, spilled more dry food than did WKY, and exhibited an inverse relation between 24-h water intake and dry food spilled. When eating a meal of dry food after 12 h food deprivation, SHR drank earlier and drank more in a 1-h test than WKY rats. Moreover, SHR exhibited (as early as wk 7) a striking pattern of interrupting eating to drink. This pattern was not present when SHR ate liquid food, and it was attenuated by infusion of water through a cheek fistula. Adult SHR (22 wk) salivated less than WKY in response to intraperitoneal 3.25 mg/kg pilocarpine nitrate. When developing SHR and WKY were maintained on liquid and solid food, SHR gained disproportionately more weight than WKY during development. When young SHR were permitted to drink no more water than WKY rats, the development of hypertension was retarded, and body weight gain was slowed. Because restricted access to food, which produced an equivalent slowing of body weight gain as did restricted access to water, also retarded development of hypertension, it appears that restricted access to water retards development of hypertension due to delayed growth. These results demonstrate that hyperdipsia, apparently caused by deficient salivary function, is not necessary for the development of hypertension in SHR.

Animals↗
PubMed1985

Effect of fetal decapitation on unbound rat plasma corticosterone concentration at the end of pregnancy.

In normal fetuses from day 16 to 21 of pregnancy, unbound plasma corticosterone concentration increases slowly from day 16 to 17, and rapidly from day 17 to 19, remaining high until birth. Fetal decapitation on day 18 produces a fall in unbound plasma corticosterone only when the mother is adrenalectomized. The ability of corticosterone to cross the placental barrier from mother to fetus or inversely is discussed.

Adrenalectomy↗
PubMed1985

Median horizontal split tip.

One of the most difficult problems encountered in rhinoplasty is lack of nasal tip projection. An innovative technique is described that utilizes the removal of a median horizontal strip of lower lateral cartilage to enhance projection, while maintaining a natural highlight and tip support without the use of grafts. The indications are limited to noses that have a widened dome requiring removal of a central strip, and tip rotation. Alternate techniques are discussed; cases and results are discussed.

Humans↗
PubMed1985

Obstructive and perforative colonic carcinoma: patterns of failure.

Carcinoma of the colon complicated by obstruction or perforation has been recognized as having a poorer prognosis than tumors without obstruction or perforation. To clarify the natural history, failure patterns, and implications for adjuvant treatment after resection with curative intent, a review of the recent Massachusetts General Hospital (MGH) experience was undertaken. From 1970 to 1977, 77 patients with obstructive colonic carcinoma and 34 patients with localized perforation at the tumor site were identified and compared with a control group of 400 patients without obstruction or perforation undergoing curative resection. All patients were observed for a minimum of five years or until the patient's death. The actuarial five-year survival and disease-free survival rates in patients with obstruction was 31% and 44%, respectively, in contrast to 59% and 75% in control patients. For patients with localized perforation, the five-year actuarial survival and disease-free survival rates were 44% and 35%, respectively. Of the 77 patients with obstructing tumors, 32 patients (42%) developed local failure--nine with local failure only and 23 patients with local failure and distant metastases. Thirty-four patients (44%) developed distant metastases. Fifteen (44%) patients of 34 with perforative colonic carcinoma had local failure. Distant metastases occurred in 15 patients (44%). The incidence of local failure and distant metastases in the control group was 14% and 21%, respectively. The rate of local failure and distant metastases increased with stage and was generally higher stage for stage than in the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma↗
PubMed1985

AIDS alert.

Explore the source record for details and available documents.

Acquired Immunodeficiency Syndrome↗
PubMed1985

The prevalence of schizophrenia in a refuge for homeless men.

The prevalence of schizophrenia in a large hostel for homeless men in an inner city area was found to be in the order of 15%. Concern is expressed that this figure represents a recent increase in the number of mentally ill among homeless men and may be related to changes in the management of chronic mental illness. Literature relating mental illness and homelessness is reviewed.

Adult↗
PubMed1985

Catabolic pathways of purine ribonucleotides and deoxyribonucleotides in lymphocytes.

Deficiency of either one of the subsequent purine catabolic enzymes adenosine deaminase or purine nucleoside phosphorylase results in immunodeficiency disease in humans. However, the mechanism by which impairment of purine metabolism may cause immunodeficiency is unclear. In the present work we have studied the catabolism of purine ribonucleotides and deoxyribonucleotides in T lymphocytes to better understand the role of purine nucleoside phosphorylase and adenosine deaminase in the immune function. It was found that purine deoxyribonucleotides are degraded via catabolic pathways distinctly different from those used for purine ribonucleotide degradation. Thus both adenine and guanine ribonucleotides are deaminated to IMP whereas purine deoxyribonucleotides are exclusively dephosphorylated to the corresponding deoxyribonucleosides. These findings may explain the relatively higher degradation rates of purine deoxyribonucleotides in mammalian cells as compared to purine ribonucleotides. The catabolism of purine nucleotides is tightly linked to the active purine nucleoside cycles which consist of the phosphorolysis of purine nucleosides and deoxyribonucleosides to their corresponding bases, their salvage to monophosphates and back to the corresponding ribonucleosides. The above observations also imply that a possible role of the purine nucleoside cycles is to convert purine deoxyribonucleotides into their corresponding ribonucleotide derivatives. Deficiencies of purine nucleoside phosphorylase or of adenosine deaminase activities, enzymes which participate or lead to the purine nucleoside cycles, thus result in a selective impaired deoxyribonucleotide catabolism and immunodeficiency.

Adenosine Deaminase Inhibitors↗