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Biomedical subjects

L B Cohen

Publications and source records attributed to L B Cohen.

At least 73 records · Page 4Linked to original sources
PubMed1985

The superior mesenteric artery syndrome. The disease that isn't, or is it?

Intestinal obstruction of the duodenum by entrapment between the aorta and the superior mesenteric artery (SMA) is an uncommon cause of megaduodenum. Despite many case reports, acceptance of the SMA syndrome as a clinical entity has been controversial on account of its confusion with other causes of megaduodenum. We therefore report a case of SMA syndrome which sharply exemplifies its clinical and anatomic features. The clinical findings are proximal duodenal obstruction with an abrupt cutoff and active peristalsis. The anatomic features of this entity are a narrow angle between the aorta and the SMA, together with high fixation of the duodenum by the ligament of Treitz and/or an anomalous SMA crossing directly over the aorta at its intersection with the duodenum. The SMA syndrome may occur as an acute self-limited event due to a reversible precipitating factor, or as a chronic recurring disorder. The acute form subsides with correction of the specific initiating factor; the chronic form responds favorably to simple surgical mobilization of the duodenum.

Adolescent↗
PubMed1985

Role of plasmapheresis in primary biliary cirrhosis.

Five patients with primary biliary cirrhosis and prolonged cholestasis underwent intensive plasmapheresis. The indications for plasmapheresis included intractable pruritus or hypercholesterolemia and xanthomatous neuropathy. Patients noted a rapid improvement of pruritus and fatigue which was sustained as long as plasmapheresis was continued. Cholesterol levels were lowered an average of 10.3 mmol/l and xanthomata were reduced in three of four patients. Two patients with painful neuropathy caused by xanthomata experienced relief of this symptom. The liver and spleen size were not affected by plasmapheresis, and activities of aminotransferases, alkaline phosphatase and titres of mitochondrial antibody remained unchanged. We conclude that plasmapheresis has a role in the therapeutic management of patients with advanced primary biliary cirrhosis who are disabled by the complications of pruritus, xanthomatous neuropathy, or hypercholesterolemia with xanthoma formation.

Adult↗
PubMed1985

Optical mapping of electrical activity in rat somatosensory and visual cortex.

We have investigated the use of optical methods for monitoring neuron activity in mammalian cortex. The cortex was stained with a voltage-sensitive dye and fluorescence was simultaneously measured from 124 areas using a photodiode array. Optical signals were detected in rat somatosensory cortex in response to small whisker movements and in visual cortex in response to light flashes to the eye. Relatively large signals were obtained during focal interictal epileptiform discharges induced by bicuculline. The measuring system had a time resolution of milliseconds and a spatial resolution of a few hundred micrometers. Simultaneous, multi-site optical recordings of activity may provide a new and potentially powerful method for studying function and dysfunction in mammalian cortex.

Animals↗
PubMed1985

Villous polyposis of the ileum: report of a case.

Villous adenomas occur only rarely in the small intestine and are often associated with malignant changes. Multiple villous adenomas of the small intestine are usually seen only in patients with familial polyposis coli. This is a report of a patient with multiple villous adenomas of the ileum associated with a carcinoma of the cecum which originated from a villous adenoma near the ileocecal valve. There was no evidence of other colonic polyps and no history of familial polyposis coli. It appears that polyposis of the small intestine is a rare clinical entity which cannot often be diagnosed due to difficulty in visualizing this area.

Adenoma↗
PubMed1983

The number and size of neurons in the CNS of gastropod molluscs and their suitability for optical recording of activity.

Several factors that affect the suitability of opticaL methods for monitoring neuron activity were evaluated in several species of gastropod molluscs. The mean cell body diameter and the total number of cells in the central nervous system were determined In 6 preparations and qualitative evaluations were made for an additional 25 species. There was a factor of 10 difference in mean diameter between species with the smallest cells (prosobranchs) and those with the largest (certain opisthobranchs). Several opisthobranchs had about 5000 central neurons; we estimate that the prosobranchs and pulmonates had at least 5 times as many neurons. When the opacity to transmitted light was measured the percent transmissions of circumesophageal ganglia were between 4% and 40%. We attempted to measure optical signals associated with spike activity in 20 gastropod species; in most species signals were readily detected in single trials.

Action Potentials↗
PubMed1983

Bacteremia after endoscopic injection sclerosis.

Endoscopic injection sclerosis is a therapeutic alternative in the management of esophageal varices. Complications of sclerotherapy have been minor, including fever, bacteremia, and abnormal chest x-ray. We performed a prospective study to evaluate the frequency of postsclerosis bacteremia. Bacteremia was detected in 14 procedures (50%). There were no cases of bacteremia in a group of control patients with esophageal varices undergoing upper gastrointestinal endoscopy without sclerosis (p less than 0.05). Bacteremia was transient and unrelated to the presence of fever or other clinical complications. The organism most commonly cultured from blood, alpha-hemolytic streptococcus, probably represents a contaminant from the oropharynx, introduced into the bloodstream during sclerosis. We conclude that injection sclerotherapy of esophageal varices is associated with a higher incidence of bacteremia than routine upper endoscopy and that selected patients may require antibiotic prophylaxis when undergoing this procedure.

Esophageal and Gastric Varices↗
PubMed1983

Infant perception of correlations among attributes.

Infants' sensitivity to correlations or co-occurrences among attributes may play a role in abilities ranging from pattern or object recognition to category formation. The present set of experiments investigated 4-, 7-, and 10-month-old infants' ability to perceive and base novelty responses on correlations among perceptual attributes in a category-like context (i.e., with the correlation embedded in a set of discriminable stimuli). In a habituation-dishabituation paradigm, 10-month-old infants clearly responded on the basis of the correlation among attributes. In contrast, 4- and 7-month-old infants responded primarily on the basis of specific featural information, but did not respond reliably to the correlation. It is suggested that the sensitivity to correlated attributes demonstrated by 10-month-old infants may have implications for the processes underlying the infants' categorization abilities.

Child Development↗
PubMed1983

Optical monitoring of activity from many areas of the in vitro and in vivo salamander olfactory bulb: a new method for studying functional organization in the vertebrate central nervous system.

We have investigated the use of voltage-sensitive dyes to monitor neuronal activity in the intact salamander olfactory bulb. After a 10- to 20-min staining period, a magnified image of an in vitro or an in vivo preparation was formed on a 124-element photodiode array. The array was used to simultaneously record absorption or fluorescence changes from 124 adjacent areas of the bulb. At the magnifications used, each detector received light from 100 to 1000 neurons. Relatively large absorption and fluorescence signals were found in response to olfactory nerve stimulation; all of the results presented were from single trials. Because of the large signal size, measurements on in vivo preparations using epi-illumination also had good signal-to-noise ratios. There were significant differences in signal time course between adjacent detectors which suggested a spatial resolution on the order of 200 microns. Tentative assignments of the cellular origins of some signals could be made from the results of paired volley experiments. The results suggest that optical monitoring of membrane potential could provide a useful method for studying neuronal organization in the intact vertebrate central nervous system.

Ambystoma↗
PubMed1981

Improvements in optical methods for measuring rapid changes in membrane potential.

In an effort to increase the utility of optical methods for measuring membrane potential in excitable cells, an additional 369 dyes were tested on giant axons from the squid. Several promising dyes with relatively large absorption and fluorescence signals are described. In addition, a simple modification of the apparatus led to a sixfold increase in the size of dye-related birefringence signals. In preparations with a suitable geometry, these signals are as large as absorption signals but photodynamic damage and bleaching are eliminated when wavelengths longer than the absorption band are used.

Animals↗
PubMed1979

Response of patients to participation in psychiatry board examinations.

The patient who volunteers to be a subject for Part II of the certifying examination in psychiatry and neurology is an indispensable but surprisingly invisible participant in a highly controversial process. A survey of the attitudes of 78 patients toward this experience revealed that although they experienced a significant degree of stress, the overwhelming majority viewed their participation in strongly positive terms. The patient's loyalty to the host institution and the manner in which the patient is prepared for the experience appear to be the major factors in determining a positive outcome.

Adult↗
PubMed1979

Concept acquisition in the human infant.

The ability of 18-, 24-, and 30-week-old infants to learn conceptual categories regarding adult female faces was examined using a habituation paradigm. Little evidence for conceptual categorization occurred at 18 or 24 weeks, but at 30 weeks infants learned to respond to "a specific female face regardless of orientation" and to "female faces in general."

Concept Formation↗