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Biomedical subjects

S Cohen

Publications and source records attributed to S Cohen.

At least 685 records · Page 38Linked to original sources
PubMed1986

Gastrointestinal tract focal mass lesions: role of CT and barium evaluations.

Fifty-eight patients with focal mass lesions involving the gastrointestinal tract were studied retrospectively. The diagnostic value of CT scans was seen by assessing the barium studies alone, then by combined review of radiographs and CT scans. Patient management decision making was similarly evaluated. CT scanning aided in diagnosis of the focal masses in 17 patients (29%), changing the differential diagnosis in eight (14%) and increasing diagnostic confidence significantly in nine (16%). In 21 (36%) additional cases, the diagnosis did not change, but CT scanning improved the understanding of disease extent. In the remaining 20 cases (34%), CT scanning did not help diagnostically. CT scanning altered patient management decisions in 19 of the 58 patients (33%). CT study was most helpful in cases of benign extrinsic cystic disease, lymphoma, and smooth-muscle tumors and less helpful for adenocarcinomas of the bowel. The value of the CT data increased as one moved from mucosal lesions to submucosal or extrinsic lesions.

Adenocarcinoma↗
PubMed1986

Selective effect of nortriptyline on smooth muscle as an anticholinergic drug: a pharmacological and clinical study.

The anticholinergic potency of nortriptyline was studied on muscle strips from human bladder and ileum. Concurrently the effect of nortriptyline low dosage therapy was studied in 21 women suffering from motor or sensory urgency and urge incontinence. Analysis of the results by the dose ratio method showed a significant difference in the affinity of the anticholinergic receptors to the antagonist. The Ki values were 0.298 microM for the bladder and 0.938 microM for the ileum. In the clinical study, the condition of 15 (71.4%) women treated with notriptyline improved considerably. The higher affinity of the drug to the receptors in the bladder than to those in the ileum may explain the positive therapeutic effect of a relatively low dose of nortriptyline in over 70% of the patients treated.

Bethanechol Compounds↗
PubMed1986

Interactions of bombesin and substance P at the feline lower esophageal sphincter.

The purpose of this study was to determine the interactions between bombesin and substance P at the feline lower esophageal sphincter (LES). Intraluminal pressures were recorded using a fixed, perfused catheter assembly. Myoelectrical activity was recorded using bipolar Ag-AgCl serosal electrodes. Bombesin, i.v., gave a dose-dependent increase in LES pressure and electronically counted spike activity. The threshold dose was 10(-7) g/kg, while the maximal dose, 10(-5) g/kg, increased LES pressure by 65.5 +/- 14.8 mmHg. The neuroantagonist, tetrodotoxin, decreased the LES response to bombesin by 74.1% +/- 7.9% (P less than 0.05), but had no significant effect on the LES response to substance P. The sphincteric response to bombesin was not inhibited by bilateral cervical vagotomy, atropine, propranolol, or phentolamine (P less than 0.10). Bombesin tachyphylaxis abolished the LES response to bombesin but had no effect on the response to substance P. Conversely, substance P tachyphylaxis completely abolished the LES response to bombesin (P less than 0.001). The substance P antagonist [D-Pro2, D-Trp7,9]substance P also significantly inhibited the LES response to bombesin (P less than 0.05). Acidification of the distal esophagus with 2.0 ml of 0.1 N HCl increased LES pressure by 32.5 +/- 5.2 mmHg (P less than 0.02). The LES response to acid was inhibited by bombesin tachyphylaxis (maximal pressure response, 4.7 +/- 2.1 mmHg, P less than 0.01 compared with control acid response). The tachyphylaxis techniques were specific for the peptides giving no effect on the LES responses to phenylephrine, bethanechol, or pentagastrin. We drew the following conclusions: (a) bombesin increased feline LES pressure via nonvagal neural pathways that were insensitive to adrenergic or cholinergic antagonists; (b) bombesin may be involved in the enteric pathways that mediate the feline LES response to distal esophageal acidification; and (c) substance P mediates the effect of bombesin at the LES and is a neurotransmitter in the LES response to acidification.

Action Potentials↗
PubMed1986

Impaired nuclear responsiveness to cytoplasmic signals in lymphocytes from elderly humans with depressed proliferative responses.

Lymphocytes from many elderly individuals exhibit depressed proliferative responses to the plant phytohemagglutinin (PHA). We have previously reported that this proliferative defect is not due to a failure to generate a cytoplasmic activator of DNA replication (ADR). In the present study, we tested the DNA synthetic response of nuclei derived from aged cells to an exogenous source of ADR. We found that nuclei from aged lymphocytes exhibiting low PHA responses were impaired in their ability to synthesize DNA in responses to ADR, compared with nuclei from younger adult donors. In contrast, those aged cells maintaining intact PHA responses provided nuclei that were also unimpaired in their response to ADR. The relationship between PHA responsiveness of the intact cells and ADR responsiveness of nuclei derived from these was a linear one. These results suggest that the depressed cellular reactivity of aged lymphocytes to PHA (when seen) may be due to a failure of these nuclei to respond to cytoplasmic stimulatory signals induced by the mitogen.

Adult↗
PubMed1986

Combined effect of glucose and verapamil in experimental cardioplegia.

In this study, we determined whether pre-ischemic enhancement of the ATP level and the addition of verapamil (a calcium blocker) to the cardioplegic solution could improve myocardial protection during cardiac arrest. Using the Langendorff preparation of the isolated rat heart plus different cardioplegic solutions, five groups of normal rat hearts and five groups of hypertrophied rat hearts were subjected to 90-minute ischemic periods at 28 degrees +/- 1 and reperfusion of 30 minutes at 37 degrees C. Group A received no cardioplegic solution; Group B received KCl, 30 mEq/L; Group C received type B perfusion with verapamil; and Group D received 15 minutes of pre-ischemic oxygenated enhancement perfusion containing KCl, 30 mEq/L, and glucose as substrate at 37 degrees C. Group E received the same perfusion as Group D, with the addition of verapamil to the enhancement perfusion. Light and E/M microscopy was performed on representative samples of left ventricular muscle. We found that pre-ischemic enhancement with KCl, glucose, and verapamil was only protective in the normal hearts after 90 minutes of ischemia. In hypertrophied hearts, the addition of verapamil to the enhancement solution was harmful. The use of pre-ischemic enhancement solution without verapamil provided the best myocardial protection after 90 minutes of ischemia in the hypertrophied hearts.

Journal Article↗
PubMed1986

Papilledema in traumatic lesion of optic nerve with amaurosis.

A patient with subdural hematoma and right amaurosis resulting from traumatic injury to the optic nerve developed papilledema in both eyes a few days after the trauma. This was interpreted as supplementary proof of the existence of axonal flow in the first weeks after occurrence of the optic axon lesion. In the amaurotic eye, the papilledema was less pronounced and disappeared more rapidly (after 3 weeks, as opposed to 6 weeks for the other eye). The nerve fiber layer disappeared between 4 and 6 weeks after the trauma.

Adult↗
PubMed1986

The elaboration of a small molecular weight cytostatic factor by lymphoblastoid lines and activated lymphocytes.

In this study, it was observed that the B lymphoid cell line RPMI 8392 produced a tumor cell cytostatic factor that is of lower molecular weight than previously described cytostatic proteins but of greater molecular weight than arachidonate metabolites. This low molecular weight factor was also found to be produced by normal murine lymphocytes upon mitogenic stimulation. Gel filtration chromatography revealed that the molecular weight of this molecule is approximately 6,500 daltons. This is the approximate molecular weight of another tumor cell directed lymphokine which we have previously described, Tumor Migration Inhibition Factor (TMIF). This lymphokine is defined by its ability to inhibit the in vitro migration of a variety of tumor cell types. It was not determined in this study whether or not the proliferation inhibitory activity and the migration inhibitory activity are due to separate molecules. However, experiments presented here demonstrate that these two activities are functionally distinct. In addition, it was found that the cytostatic factor described here, unlike higher molecular weight cytostatic factors, was not associated with cytotoxicity.

Animals↗
PubMed1986

Feedback regulation of the secretion of a thymic hormone (thymulin) by human thymic epithelial cells in culture.

The production of the thymic hormone, thymulin (FTS), was studied in primary cultures of human thymic epithelium by immunofluorescence using monoclonal anti-thymulin antibodies. The number of thymulin-containing cells and the thymulin level in the culture supernatant increased gradually during the culture. Addition of synthetic thymulin to the culture medium reduced significantly the increase of thymulin-containing cells. Conversely, addition of monoclonal anti-thymulin antibody from the beginning of the culture exacerbated the spontaneous increase of thymulin-containing cells and abrogated the effects of thymulin. Combined with similar data previously reported in vivo, these results demonstrate that thymulin is actively produced by cultured thymic epithelial cells and that its synthesis can be down-regulated by the hormone itself.

Antibodies, Monoclonal↗
PubMed1985

Antihistaminic properties of AF-14, an experimental quinuclidine derivative: discrimination between two histaminergic sites in both guinea-pig ileum and bladder.

AF-14 (1-aza-4-phenyltricyclo[6.2.2.0(2,7)]dodecan-5-one), a selective antimuscarinic agent, was shown to block the histamine-induced contractile response in Krebs solution in guinea-pig ileum and bladder. Careful linear regression analyses of the concentration-response relationship revealed that AF-14 antagonism consisted of two sequential and distinct phases, corresponding to an early phase and a late phase of the contractile response to histamine. In the late phase, the action of AF-14 was consistent with competitive antagonism, its pA2 (95% confidence limits) being 5.80-6.06 (ileum) and 5.66-5.80 (bladder). In the early phase, AF-14 almost completely blocked the contractile response at a concentration of 100-300 nM, which was much less than required to block the late phase or cholinergic contractions of the ileum or bladder. It is concluded that AF-14 discriminates between two histamine-sensitive sites that mediate muscle contraction in each of the two organs.

Animals↗