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Biomedical subjects

L Cohen

Publications and source records attributed to L Cohen.

At least 523 records · Page 29Linked to original sources
PubMed1980

HCO3-Cl exchange transport in the adaptive response to alkalosis by turtle bladder.

The isolated turtle urinary bladder acidifies its mucosal (M) solution, and the rate of acidification (JH) is equivalent to the short-circuit current after Na+ transport is abolished by ouabain. When HCO3(-) is present in the serosal solution it is secreted into M in an electroneutral exchange for absorbed Cl-. The rate of HCO3(-) secretion (JHCO3(-)) can be measured by pH stat titration after JH is nullified by an opposing pH gradient. With use of these methods JH and JHCO3 were measured sequentially in bladdes from control animals and animals fed NaHCO3 (alkalosis) or NH4Cl (acidosis). JH in alkalosis (57 +/- 6 micro A) was ot different from control values (53 +/- 7 micro A). JHCO3, however, was nearly 40% higher in alkalosis (1.63 +/- 0.11 vs. 1.17 +/- 0.14 mu mol x h-1 x 8 cm-2). In contrast, JHCO3 in acidosis was similar to control values (0.89 +/- 0.15 mu mol x h-1 x 8 cm-2) but JH was increased. As judged from Cl- fluxes, neither alkalosis nor acidosis altered the electroneutral coupling between HCO3(-) secretion and Cl- absorption. JH and JHCO3 appear to be independent processes in the turtle bladder that are capable of responding independently to physiologic changes in the acid-base status of the intact animal.

Absorption↗
PubMed1980

Intramuscular sedation technique.

A sedative technique with meperidine hydrochloride and promethazine hydrochloride via an intramuscular injection is presented. We believe this is an excellent technique because of the safety to the patient and the ease of administration. Like any technique using potentially dangerous medications, practitioners and their staff must be familiar with and prepared for possible complications. When the technique is mastered, it will be a valuable addition for treatment of certain mentally and physically handicapped patients.

Anesthesia, Dental↗
PubMed1980

Differences in enzyme efflux from dystrophic mouse skeletal muscle and heart.

The efflux of the enzymes, creatine kinase (CK) and lactate dehydrogenase (LDH) from isolated normal and dystrophic mouse (C57BL/6J-dy) skeletal muscle and heart has been studied. Older (5-9 months) dystrophic mouse triceps contained only 63% of normal CK. At 3.5-10 weeks, dystrophic gastrocnemii had 72% and 61% of normal for males and females, respectively. By 5-7 months, the levels dropped to only 26% and 15% of normal. When skeletal muscle efflux was normalized to enzyme content, dystrophic muscle was not significantly different from normal for the first three hours, and was lower than normal in the 3-5 hour period. This was true for both triceps and gastrocnemius. Similarly, no difference in LDH efflux from gastrocnemius was seen between control and dystrophic mice. In contrast, there was no difference in enzyme concentration of normal and dystrophic hearts. Despite this, hearts from dystrophic mice had a higher efflux of both CK and LDH in the first three hours, but not beyond. The results indicate that under the conditions of these studies, dystrophic skeletal muscle was not, but heart was, more permeable to muscle enzymes than normal muscle.

Animals↗
PubMed1979

Physical properties of DNA and chromatin isolated from G1- and S-phase HeLa S-3 cells. Effects of histone H1 phosphorylation and stage-specific nonhistone chromosomal proteins on the molar ellipticity of native and reconstituted nucleoproteins during thermal denaturation.

To help delineate how changes in chromatin organization are related to DNA replication and transcription during the HeLa S-3 cell cycle, we have extended previous studies of the composition and structure of chromatin in synchronized G1- and S-HASE CELLS. By analyzing changes in molar ellipticity at 276 nm ([theta 276]) during thermal denaturation, it was found that double-helical DNA molecules in native chromatin have different optical activities and thermal stabilities at these two stages of the cell cycle. Furthermore, profiles of d[theta 276]/dT vs. T indicate that native G1- and S-phase chromatins contain different families of DNA superstructures. To help determine the causes and functional significance of these chromatin reorganizations during the cell cycle, we compared the optical activities and thermal stabilities of DNA in native chromatin with protein-free DNA and DNA in nucleoproteins reconstituted in vitro by NaCl-urea gradient dialysis. In addition, we examined levels of histone phosphorylation, histone acetylation, and types of histone and nonhistone chromosomal proteins (NHCP) found in G1- and S-phase cells and in purified hydroxylapatite, (HAP) fractions of these nuclear proteins which were used for in vitro reconstitution. The results of the present studies indicate that changes in H1-DNA-NHCP interactions occur in vivo, are associated with the phosphorylation of histone 1 molecules, and appear to be responsible for the relaxation of compact G1-phase chromatin superstructures into more open S-phase configurations during the HeLa S-3 cell cycle.

Cell Cycle↗
PubMed1979

Supine pedal venous measurement in patients with venous disease.

The measurement of supine pedal venous pressure as a screening test for deep venous thrombosis is re-evaluated. In 83 extremities studied in 50 patients, the false-positive rate was 62%, the false-negative rate 8%. Chronic venous disease, whatever its etiology but particularly in association with the post-phlebitis syndrome, can be a source of error in relying upon this measurement.

Chronic Disease↗
PubMed1979

Complications related to the administration of general anesthesia in 600 developmentally disabled dental patients.

A total of 600 handicapped patients had dental rehabilitation under general anesthesia during an eight-year period. Handicaps included mental retardation, cerebral palsy, Down syndrome, seizure disorders, autism, cystic fibrosis, osteogenesis imperfecta, and muscular dystrophy. No significant complications developed in the majority of patients. This is attributed to thorough preoperative evaluation, appropriate anesthetic management, and vigilant postoperative observation.

Adolescent↗
PubMed1979

Detection, prediction, and significance of perioperative myocardial infarction following aorta-coronary bypass.

One hundred consecutive patients undergoing aorta-coronary bypass grafting (ACBG) alone, without ventricular venting, were prospectively studied to determine the incidence and consequence of perioperative myocardial infarction (PMI) and the clinical variables that were predictive of PMI. Incidence was determined by serial electrocardiography (ECG) 100 patients; serum CK, GOT, and LDH (100 patients). CK isoenzymes (qualitative 100 patients, quantitated 50 patients); vectorcardiography (VCG) (78 patients); and 99mtechnetium pyrophosphate scintigraphy (TcPyp) (52 patients). The incidence of PMI by ECG was 9%; an additional 8% of cases was diagnosed by enzymes alone. The incidence of diagnostic change by VCG was 19% and by scintigraphy, 25%. Using at least one changed variable of the remaining three as the reference standard, the relative sensitivity and relative specificity of given variables in the diagnosis of PMI were as follows: ECG 67% and 100%, respectively; VCG 85% and 94%; scintigraphy 92% and 97%; and serum enzymes 86% and 96%. By univariate analysis, unstable angina was the only significant predictor of PMI. The operative mortality rate was 2% and the mortality rate at 12 months was 5%. There was a significantly greater mortality rate in patients with PMI diagnosed by ECG (p less than 0.01), in patients with unstable angina pectoris before operation (p less than 0.05), and in women (p less than 0.05).

Analysis of Variance↗
PubMed1979

Factors influencing mouse heart creatine kinase efflux and ultrastructure.

An isolated mouse heart model has been developed to study the extracellular factors which influence the loss of myocardial enzymes. When added to a tris-HCl buffer/salt mixture at 25 degrees C, glucose, phosphate ion, increased osmolarity, oxygen exclusion and calcium reduced enzyme leakage. Of these, calcium effects on enzyme leakage and ultrastructure were assessed in detail. Concentrations less than or equal to 10(-4) M had no significant effect on enzyme efflux over a 5 hour period. At higher concentrations (10(-3) and 10(-2) M Ca2+), creatine kinase (CK) efflux was significantly altered in a time dependent fashion. In the first hour, 10(-3) and 10(-2) M Ca2+ reduced CK leakage to 33% and 25% of the control values, respectively; and to about 50% of the control values in the second and third hours. This protective effect was lost between the third and fifth hours, when an enzyme efflux 80% greater than control was observed. These studies indicated that CK leakage from mouse heart can be retarded for up to 3 hours by appropriate Ca2+ concentrations. The initial ultrastructural change, in the absence of Ca2+, was a dilatation of the transverse tubules, which gradually enlarged by coalescence. This was followed by a gradual disintegration and ultimate condensation of the myofibrils leaving altered mitochondria floating freely in an apparently intact sarcolemmal bag. These changes appeared to be delayed by Ca2+ for 3 hours, after which no protective effect was evident. Thus, CK leakage is a measure of myocardial autolysis, and numerous simple measures can retard this autolysis for several hours. This raises the possibility of prolonging the preservation of the normal heart in vitro.

Animals↗
PubMed1979

A preliminary report of the efficacy of Debrisan (dextranomer) in the debridement of cutaneous ulcers.

A randomized trial involving 50 patients has demonstrated that a new type of debriding agent, cross-linked dextran beads with the trade name Debrisan (dextranomer, Pharmacia, Inc.), will produce rapid healing of cutaneous ulcers which have been resistant to conventional therapy over the long-term. Evaluation in terms of a number of therapeutic parameters, including rate of healing, dehydration, sterilization, loss of symptoms, and improvement in physiology, is included in this preliminary study.

Administration, Topical↗