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Biomedical subjects

A Cohen

Publications and source records attributed to A Cohen.

At least 811 records · Page 45Linked to original sources
PubMed1983

Preoperative irradiation for unresectable rectal and rectosigmoid carcinomas.

The records of 25 patients with unresectable carcinoma of the rectum and rectosigmoid who received preoperative radiation therapy (RT) were reviewed. Twenty patients were considered to be resectable following RT (80%). Sixteen patients (64%) underwent curative resections. All patients with unresectable tumors following RT died with tumor within two and one half years (median survival, 11 months). For patients undergoing curative resection, the probability of two- and five-year survival was 56% and 43%, respectively. In this latter group, five of seven patients with treatment failures (71%) had a pelvic component of disease. The incidence of pelvic recurrence was correlated with the pathologic stage, extent of resection and preoperative radiation dose. The need for more aggressive treatment for patients with these advanced tumors is emphasized. Future treatment alternatives are discussed.

Aged↗
PubMed1983

Plasmidic recombination in Escherichia coli K-12: the role of recF gene function.

Interplasmidic and intraplasmidic recombination proficiencies were determined in E. coli bacterial strains carrying rec mutations. Our results defined the role of recF gene function, recB, recC, and sbcB gene products (exonuclease V and exonuclease I) in plasmidic recombination in wild-type E. coli cells and in cells in which the recE recombination pathway is activated. RecF gene function is required for interplasmidic recombination regardless of the recB recC genotype. Intraplasmidic recombination is recF dependent in cells having a functional exonuclease V, but not in recB recC mutants. Exonuclease V activity inhibits both interplasmidic and intraplasmidic recombination via the recE pathway.

Bacterial Proteins↗
PubMed1983

The determination of maternal and foetal rat plasma corticosterone concentration in late pregnancy by competitive protein binding analysis.

A procedure for the determination of corticosterone in 20 microliters of rat plasma, in maternal and foetal late pregnancy with a protein binding radioassay, is described. The method is suitable in a range of 0.5-3 ng of corticosterone. An amount of 0.5 ng can be detected with a coefficient of variation for duplicate of 13%. This procedure seems to be specific for glucocorticosteroids. The comparison of the results obtained with fluorimetry and the competitive protein binding radioassay show the reliability of both methods although the protein binding radioassay is much more sensitive.

Animals↗
PubMed1983

A model for the temperature distribution in skin noxiously stimulated by a brief pulse of CO2 laser radiation.

The application of localized noxious heat stimuli to the skin, generated by brief infrared radiation pulses emitted by a CO2 laser, is a relatively new experimental technique for the thermal induction of pain in humans and in experimental animals. This study proposes a model for the spatial (3-dimensional) and temporal distribution of the skin temperature during and following a radiation pulse. The heat equation is written and solved, using thermal and optical constants of human skin reported in the literature. The solution is approximated, with a very small error, by a closed form expression, having a simple physical interpretation. This model is applied to analyze a typical set-up currently in use in our laboratory. The results show a significant difference between the temperature of the surface of the skin and that of the border between the epidermis and the dermis, which is the location of the most superficial receptive nerve ends. It is shown that, for the set-up examined, these nerve ends reach a temperature of 45 degrees C, known to be the human pain threshold, 30-40 ms after pulse onset. Moreover, it is also shown that they may remain above threshold temperature for up to a few hundreds of milliseconds (considerably outlasting pulse cessation). In addition, it is shown that the area in which nerve ends reach this threshold is a circle with a very small radius (1-2.5 mm). The implications of the results on the double sensation experienced by humans, and on the extremely powerful EEG correlates, are discussed.

Humans↗
PubMed1983

Valvular heart disease in adults. When to call in the surgeon.

Valvular heart disease is now amenable to surgical intervention. Valve surgery needs to be considered at the appropriate time so that patients are not denied the benefit of operation. Patients with indications for surgery should be operated on before progressive left ventricular dysfunction or the complications attendant to valvular heart disease develop. Delay of indicated surgery may increase the operative risk. This does not mean that patients should be referred for surgery before the appropriate indications appear. It does mean, however, that patients with valvular heart disease should be followed for evidence of progressive signs and symptoms attendant to the disease. Clinical and laboratory evidence of valvular and/or ventricular dysfunction determines when surgical intervention is necessary. Once indications for valve surgery appear, prompt referral is indicated.

Adult↗
PubMed1983

Effect of diclofenac-sodium (Voltaren) on the electrical charge of human platelet membrane.

Platelets incubated with prostaglandin synthetase inhibitors, i.e. aspirin (ASA) and diclofenac-sodium (Voltaren) show a decreased capability to aggregate. While ASA induces the complete loss of platelet pseudopodia, Voltaren causes the appearance of long, needle-shaped pseudopodia, a finding which may suggest a rather increased tendency to aggregate. Platelets labeled with ferritin hydrazide and examined with a transmission electron microscope and by X-ray analysis show a greater deposition of ferritin hydrazide after incubation with Voltaren in comparison to those incubated with ASA and to the controls. This finding suggests an increased negative charge of the stretched platelet membrane after incubation with Voltaren with a subsequent increase in the repulsive forces between platelets.

Aspirin↗
PubMed1983

Late pregnancy maternal and fetal time-course of plasma ACTH and corticosterone after continuous ether inhalation by pregnant rats. Cytoimmunological study of fetal hypophyseal cells.

In order to compare the time-course and the amplitude of the hypophyseal-adrenal response to stress in both the mother and the fetus, female rats on day 20 of pregnancy were subjected to continuous ether inhalation and killed at different time intervals after the onset of stress (5, 10, 20, 30, 40 and 60 min). Plasma ACTH was determined by radioimmunoassay and plasma corticosterone by a competitive binding radioassay. In normal pregnant rats subjected to ether stress, the release of ACTH is tenfold higher than in the fetus, but the amplitude of maternal and fetal corticosterone release after this stimulus is very similar; the response occurs faster in the mother than in the fetus. In pregnant rats adrenalectomized 4 h before ether stress procedure, the ACTH release is smaller than in normal mothers and the plasma corticosterone values, despite the adrenalectomy, are close to those observed in resting rats at the same time of day. The fetal corticosterone release is still elevated under this stimulus and occurs faster than in fetuses from normal mothers. The cytoimmunological study of fetal hypophysis revealed both hypertrophy and hyperplasy of ACTH-containing cells during the first minutes of ether anesthesia.

Adrenalectomy↗
PubMed1983

Muscle relaxing agent in cutaneous leiomyoma.

The management of pain in cutaneous leiomyoma involving large areas of the body surface is problematic. The surgical approach is not practical and the pain in these cases is refractory almost to all analgesic agents. This is a description of a case in which a muscle relaxing agent proved to be the only effective therapeutic approach.

Adult↗
PubMed1983

Hypoglycemia in patients receiving disopyramide phosphate.

Postmarketing drug surveillance revealed the occurrence of hypoglycemia associated with the use of disopyramide phosphate (Norpace) for the control of ventricular arrhythmias. The data obtained suggest that elderly patients or those with impaired hepatic or renal function may be more at risk of developing hypoglycemia while taking disopyramide. In a clinical study, nine healthy male volunteers were dosed with disopyramide to steady-state concentration. Comparison of the glucose levels during periods of fast, when the presence of food did not present a confounding factor, suggested that disopyramide may have a glucoregulatory effect in humans. A placebo-controlled clinical study, conducted in 11 healthy, male subjects, demonstrated that disopyramide evoked a small, but statistically significant, decrease in glucose levels during both the fed and fasted state. None of the classical signs or symptoms associated with hypoglycemia were noted during either of these clinical studies.

Aged↗
PubMed1983

The diagnostic value of serum copper/zinc ratio in gynecological tumors.

Serum copper levels (SCu) and serum zinc levels (SZn) were determined on admission in 73 women hospitalized for suspected gynecological tumor. Twenty-five of the women were subsequently found to have malignant tumor, while 48 had benign growths. The serum Cu/Zn ratio of the malignant group (2.13 +/- 0.53) was significantly (p less than 0.001) higher than that of the benign group (1.45 +/- 0.25). A good correlation was established between the Cu/Zn ratio and the stage of the malignant tumor. Serum copper level showed a linear correlation (R = 0.878) with serum ceruloplasmin values. These results indicate that the serum Cu/Zn ratio may be used as a valuable predictor of the presence of malignant gynecological tumor and its stage.

Ceruloplasmin↗
PubMed1983

Haemin affects platelet aggregation and lymphocyte mitogenicity in whole blood incubations.

The effect of haemin on platelet aggregation induced by epinephrine, ADP, collagen and arachidonic acid was examined, as well as on lymphocyte mitogenicity induced by phytohaemagglutinin (PHA). The receptor mediated platelet inducers, such as epinephrine and ADP were enhanced to maximal aggregation capacity by exogenous haemin, whereas non-receptor inducers, i.e. collagen and arachidonic acid, showed a marked decrease of platelet aggregation. The results indicate the involvement of haemin in receptor mediated platelet activation. PHA-induced lymphocytes treated with haemin showed a reduced rate of 3H-thymidine incorporation. Inhibition of lymphocyte mitogenic activity was dose-dependent on haemin concentration. Ultrastructural localization of haemin binding sites was performed by the osmiophilic reaction of benzidine. Haemin was shown to bind to the cell membrane and to the granule membrane of the platelets. The lymphocyte membrane was in practice masked by a layer of haemin.

Adenosine Diphosphate↗
PubMed1983

Selective toxicity of deoxyguanosine and arabinosyl guanine for T-leukemic cells.

Deoxyguanosine is selectively cytotoxic to leukemic cells from patients with T-acute lymphoblastic leukemia (T-ALL), whereas all other leukemic cell types were significantly less sensitive. Arabinosylguanine, a deoxyguanosine analog resistant to cleavage by purine nucleoside phosphorylase, is a more potent inhibitor of DNA synthesis in T-leukemic cells than deoxyguanosine and retains a selective cytotoxic activity for T-leukemic cells. Deoxyguanosine and arabinosylguanine are phosphorylated to deoxyGTP and arabinosylGTP, respectively, by T cells but not by other cell types. The phosphorylation and the cytotoxicity of arabinosylguanine are prevented by deoxycytidine. The selectivity of arabinosylguanine for malignant T cells, the exquisite sensitivity of these cells to the drug, and the failure of PNP to cleave the nucleoside indicate its potential in the treatment of T-ALL.

Arabinonucleosides↗