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Biomedical subjects

S Cohen

Publications and source records attributed to S Cohen.

At least 955 records · Page 53Linked to original sources
PubMed1980

Cronkhite-Canada syndrome: report of an unusual case.

This report describes the findings in a 58-yr-old woman with multiple gastrointestinal polyps, associated with diarrhea, abdominal discomfort, hypoalbuminemia, alopecia, nail atrophy, and pigmentary changes. The patient met the criteria of the Cronkhite-Canada syndrome. Pathological evaluation of her polyps revealed regenerative (inflammatory) pseudopolyps, rather than true adenomatous polyps recorded in some earlier descriptions of patients with this syndrome. This is the first report of the association of Cronkhite-Canada syndrome with multiple myeloma.

Alopecia↗
PubMed1980

Colonic dysfunction in diabetes mellitus.

Colonic myoelectrical and motor activity were measured in 12 patients with diabetes mellitus. Diabetic patients with severe constipation were compared to diabetics with mild or no constipation. Gastric emptying and peripheral nerve conduction studies were performed in all patients. Normal subjects had a rapid increase in colonic spike and motor activity (P < 0.001) within the first 30-min postprandial period. Diabetic patients with mild constipation had a postprandial increase in colonic motility; however, the response was delayed to 60-90 min after eating. Diabetic patients with severe constipation had no postprandial increase in colonic motility. There was no correlation between colinic motility and gastric emptying of a liquid meal (r = 0.23) (P > 0.05) or peripheral nerve conduction (r = 0.36) (P > 0.05). Neostigmine (0.5 mg, intramuscularly) or metoclopramide (20 mg, intravenously) increased colonic spike (P < 0.005) and motor (P < 0.005) activity in all diabetic subjects regardless of their symptoms. These studies suggest that patients with diabetes mellitus and severe constipation may have an autonomic neuropathy which leads to an absent postprandial gastrocolonic response.

Action Potentials↗
PubMed1979

ColE1 DNA sequences interacting in cis, essential for mitomycin-C induced lethality.

Protein synthesis and survival of colicinogenic bacteria carrying different ColE1 deletion and insertion mutants, were followed in presence or absence of the inducing agent mitomycin-C. It is concluded that active colicin is not involved in the process leading to death of the induced colicinogenic cell. The region of ColE1, essential for cell induced lethality, is carried on the DNA between map positions 0.74 to 0.27. In this region the DNA sequences carried between 0.74 to 0.79 and 0.0 to 0.27 are essential, while those located between 0.79 to 0.0 are nonessential for commitment to death. A cis interaction of the ColE1 DNA sequences in the essential regions is probably necessary for cell induced lethality. Some possibilities for such a cis interaction are suggested and discussed.

Bacterial Proteins↗
PubMed1979

Human macrophage migration inhibition factor: evidence for subunit structure.

Macrophage migration inhibition factor (MIF) derived from human lymphoid cell lines was found to lose biologic activity on dialysis. Although activity was not recovered in the dialyzate, mixing experiments demonstrated that the components in the retentate and dialyzate could reassociate to restore activity. The fragment of larger molecular weight (less than 10,000) could inhibit the activity of intact MIF, whereas the smaller molecular weight fragment (5,000 to 10,000) could not. These findings suggest that human MIF is composed of at least two noncovalently linked subunits. In analogy to the situation for certain bacterial toxins, one of these may represent an attachment piece for a target cell membrane receptor.

Cell Line↗
PubMed1979

Rapid enhancement of protein phosphorylation in A-431 cell membrane preparations by epidermal growth factor.

Membranes prepared from A-431 human epidermoid carcinoma cells retained the ability to bind 125I-labeled epidermal growth factor (EGF) in a specific manner. In the presence of [gamma-32P]ATP and Mn2+ or Mg2+, this membrane preparation was capable of phosphorylating endogenous membrane components, including membrane-associated proteins; the major phosphorylated amino acid residue detected in partial acid hydrolysates was phosphothreonine. The binding of EGF to these membranes in vitro resulted in a severalfold stimulation of the phosphorylation reaction; again, the major phosphorylated amino acid residue detected in partial acid hydrolysates was phosphothreonine. Membrane-associated dephosphorylation reactions did not appear to be affected by EGF. The phosphorylation reaction was not stimulated by cyclic AMP or cyclic GMP in the absence or presence of EGF. The phosphorylation system of the membrane was able to utilize [gamma-32P]GTP in both the basal and EGF-stimulated reactions. The enhanced membrane phosphorylation was specific for EGF and its derivatives; a wide variety of other peptide hormones were ineffective. The A-431 membrane preparation also was capable of phosphorylating exogenous proteins, such as histone, phosvitin, and ribonuclease, by a process which was stimulated by EGF. These findings suggest that one of the biochemical consequences of the binding of EGF to membranes is a rapid activation of a cyclic AMP-independent phosphorylating system.

Carcinoma, Squamous Cell↗
PubMed1979

Offset rate of action of muscarinic antagonists depends on their structural flexibility.

Time course measurements of the action of muscarinic antagonists were performed in the spontaneously beating carp atrium. Several high affinity drugs, which embody the quinuclidine structure were examined. The structural flexibility of these molecules was reflected in the dissociation of the drugs from the muscarinic receptor. The dissociation of rigid drugs was very much prolonged as compared to flexible drugs of the same affinity.

Acetylcholine↗
PubMed1979

Modification by SQ 14225 of blood pressure and adrenal catecholamine response to hemorrhage.

SQ 14225 infusion to cats exposed to hemorrhage suppressed adrenomedullary catecholamine release. The immediate compensatory blood pressure response was unaffected, while the later compensatory response was of a higher magnitude in intact cats that in SQ 14225-treated animals. Adrenal gland blood flow was better preserved in SQ 14225-treated hemorrhaged cats than in cats exposed to hemorrhage only. These data emphasize the role of angiotensin II in adrenal catecholamine and blood pressure responses to hemorrhage.

Adrenal Glands↗
PubMed1979

Immunity to malaria.

Malaria remains prevalent throughout tropical and subtropical regions and almost a third of the World's population is exposed to the risk of infection. There is currently a serious resurgence of the disease in Asia and Central America. The failure of global eradication measures based upon the use of insecticides and chemotherapy has resulted from difficulties of practical implementation compounded by the spread of insecticide and drug resistance. Repeated natural infection does not produce detectable resistance to the exo-erythrocytic cycle of malaria in man. Irradiated sporzoite vaccines do, however, induce stage specific immunity in murine malaria and in a proportion of human subjects. Vaccinated individuals remain susceptible to blood stage infection which causes clinical malaria. In addition the vaccine is unstable and must be administered by intravenous inoculation. Since neither sporogonic nor exo-erythrocytic parasite development is cyclical in human malarias, there is little prospect for vaccine production through cultivation of these stages. The inhabitants of hyperendaemic areas become increasingly resistant to malaria during childhood and adolescence, through the slow development of specific, acquired immunity to asexual blood stage parasites. Immunity is mediated by antibody, which blocks merozoite invasion of red cells, as well as by cell mediated mechanisms and non-specific cytotoxic agents. Vaccination with merozoites induces long lasting immunity of broad serological specificity active against the blood-stage of the parasite. Merozoite vaccines can be preserved by freeze drying and harvested from continuous cultures of blood stage parasites. The major problem in development of a human merozoite vaccine concerns the requirement for Freund's complete adjuvant which is not acceptable for man. The effective immunity induced by vaccination contrasts with the slow development of incomplete resistance which follows repeated natural infection. The latter is associated with the generation of immune suppressor cells, lymphoid cell mitogens and soluble antigens, and in some species by the occurrence of antigenic variation--all of which may favour parasite survival. It is probable that vaccination with non-viable antigen of appropriate composition, induces immune effector processes without activating mechanisms which allow parasites to escape the consequences of immunity. Many effective vaccines such as those against measles, poliomyelitis, tetanus and rabies are commercially available but barely used in the developing world. The affected nations cannot afford their purchase, nor do the means exist for their distribution. It follows that if a safe and effective malaria vaccine were to be developed, its bulk manufacture and administration would require massive international support and cooperation.

Animals↗
PubMed1979

Laser iridotomy in closed-angle glaucoma.

An argon laser iridotomy was performed on 53 eyes of 34 patients with closed-angle glaucoma. Technically, all of the iridotomies were successful. Blue irides were more resistant to treatment than brown irides. The iridotomies were performed with high energy of 2 W and a very short exposure time of 0.01 to 0.04 s, thus minimizing thermal damage to adjacent tissues. Patients with narrow angles who underwent preventive laser irodotomy benefited most from the procedure, and all the eyes of this group maintained a normal intraocular pressure (IOP) after the iridotomy. Of the 20 eyes with acute angle-closure glaucoma, 17 maintained a normal IOP after iridotomy, and only three were resistant to this treatment, calling for filtering operations later. The IOP of eyes with chronic closed-angle glaucoma did not change after the procedure, and the iridocorneal angles remained practically the same. Argon laser iridotomy by this technique is highly recommended as the procedure of choice for eyes with acute angle-closure glaucoma and for preventive iridotomy in the fellow eye. The procedure is simple, is performed in the outpatient clinic, and engenders no major complications.

Follow-Up Studies↗
PubMed1979

Clinical and manometric findings in benign peptic strictures of the esophagus.

To determine the possible factors that may contribute to the development of peptic stricture of the esophagus, clinical and manometric features were compared in patients with symptomatic gastroesophageal reflux and those with peptic strictures of the esophagus. Patients with stricture were older and had a longer duration of heartburn than patients without a stricture. Most importantly, patients with stricture had a more marked decrease in lower esophageal sphincter (LES) pressure, 4.9 +/- 0.5 mm Hg, than patients without a stricture, 7.5 +/- 0.6 mm Hg, P less than 0.01. The LES pressure in all patients with stricture was below 8 mm Hg, and did not overlap with normal values. Patients with stricture had either a nonspecific motor abnormality of aperistalsis (64%), compared to patients with symptomatic reflux (32%), P less than 0.05. Thus, peptic stricture of the esophagus is commonly associated with a long duration of reflux symptoms in patients with a very low LES pressure and esophageal motor disorder.

Age Factors↗