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Biomedical subjects

R Feinstein

Publications and source records attributed to R Feinstein.

At least 19 recordsLinked to original sources
PubMed1992

Anesthesia for laparoscopic cholecystectomy. Is nitrous oxide contraindicated?

Since it has been suggested that the use of nitrous oxide (N2O) may contribute to bowel distention, we evaluated the effects of N2O on operating conditions during laparoscopic cholecystectomy in 50 healthy patients using a double-blind protocol design. All patients received the same preanesthetic medication (midazolam, 2 mg intravenously) and induction of anesthesia consisted of intravenously administered fentanyl 1.5 micrograms.kg-1, thiopental 4-6 mg.kg-1, and a nondepolarizing muscle relaxant. For maintenance of anesthesia, patients were randomly assigned to one of two treatment groups: group 1 (n = 26) received isoflurane with 70% N2O in oxygen (O2), whereas group 2 (n = 24) received isoflurane in an air/O2 mixture. The surgeon (blinded to the anesthetic technique) estimated the degree of technical difficulty before beginning the operation using a five-point scale. At 15-min intervals throughout the operation, the surgeon was asked to evaluate both "overall operating conditions" and degree of "bowel distension" using independent five-point scales. At the end of the operation, the surgeon was asked whether or not N2O had been used as part of the anesthetic technique. There were no significant intraoperative differences between the two groups with respect to operating conditions or bowel distension. More importantly, there was no time-related change in either variable during the course of the operation. Finally, the incidence of postoperative nausea and vomiting was similar in both treatment groups. The surgeon was able to correctly determine that N2O had been administered only 44% of the time. Thus, N2O had no clinically apparent deleterious effects during laparoscopic cholecystectomy.

Adult↗
PubMed1991

A simple height-specific and rate-specific step test for children.

Recently an anatomic model was reported for adults that standardized the platform height for step tests using an individual's stature and a specified hip angle. In order to determine if the model could be used to predict the platform height for children, platform heights were calculated and hip angles were measured in 146 boys and 140 girls ages 6 to 18 years who were divided into four age groups (6 to 8, 9 to 11, 12 to 15, and 16 to 18 years old). There were no statistical differences between measured and calculated hip angles in any of the age groups. In order to determine the validity for predicting maximal oxygen consumption from stepping using a calculated platform height, three step tests were employed using one platform height and stepping frequencies of 22, 26, or 30 ascents/min. Each of the tests was administered to 93 6- to 18-year-olds. Correlation coefficients between the 15-second recovery heart rate after stepping and maximal oxygen consumption measured on a treadmill were .80 at 30 ascents/min, .79 at 26 ascents/min, and .81 at 22 ascents/min. Each of the correlation coefficients was significant at the P less than .01 level. It can be concluded that the model is valid for standardizing the platform height for children for use with a single stage step test for estimating maximal oxygen consumption.

Adolescent↗
PubMed1991

Heat illness in football players in Alabama.

Fall football practice in Alabama generally begins during the later months of summer during some of the hottest periods of the year. Exercise during these periods significantly exposes young athletes to risks of heat illness and possible death and is made even more dangerous while training in full football uniform. In order to delineate specific guidelines to reduce the risk of heat illness, optimal practice times and fluid replacement schedules were studied for the state of Alabama. A review of five-year climatological data (1984-1988) for the months of August and September were conducted for four geographic regions of the state. A study of the data revealed that there were no environmental combinations at any time periods during the month of August for any locale in the state that would be considered safe for outdoors practice in full uniform. Similar results were recorded for September for cities in the south-central portion of the state. There were only two time periods during which players could practice outdoor with extreme caution. The periods were at 0900 and 1800 hrs in the north-central and northern portions of the state. If practice is conducted outdoors in Alabama during August and September, copious amounts of water should be consumed prior to practice; frequent water breaks should be scheduled throughout practice at which time each player should consume 150 - 200 ml; and the player should be carefully monitored for signs of heat illness.

Football↗
PubMed1989

Occurrence of intracytoplasmic inclusion bodies in the digestive epithelium of fallow deer (Dama dama L).

Intracytoplasmic inclusion bodies were observed in the digestive epithelium of fallow deer (Dama dama L) suffering from bovine virus diarrhea/mucosal disease. Similar inclusion bodies were also found in the ruminal epithelium of fallow deer subjected to overfeeding by supplementary food. Inclusion bodies were not found in the upper alimentary mucosa of clinically healthy deer but were frequently found when these tissues were subjected to autolysis. At electron microscopical studies the inclusion bodies were found to consist of granular protein-like material encircled by a single membrane. Such inclusion bodies may constitute a non-specific degenerative cell response which could be elicited by diverse factors including autolysis.

Animals↗
PubMed1988

[Characteristics of hereditary colorectal carcinoma without pre-existing polyposis].

The report presents two families with inherited predisposition to colorectal carcinoma without preexisting polyposis coli. In these families the disease is characterized by early onset and tumor localization in the right side colon. Screening colonoscopy should be started early. Families of this kind are of greatest value for genetic marker studies.

Adenocarcinoma↗
PubMed1979

Monitoring of cortical excitability during induced hypotension in aneurysm operations.

The electrical excitability of the cortex was monitored during craniotomy in 10 patients with ruptured aneurysms, to test their ability to tolerate hypotensive anesthesia. Excitability was assessed by measuring the direct cortical response, a response evoked and recorded from the surface of the brain. Previous animal experiments had shown that this response can be used as an index of cerebral blood flow. In the 10 patients the response progressively declined as the blood pressure was lowered and increased when the pressure was restored. Observation of the direct cortical response during aneurysm operations is a practical method for evaluating the electrophysiological responsiveness of the cortex during hypotension, and the authors suggest that decreases in the amplitude of the response are related to decreased in local cerebral blood flow.

Adult↗
PubMed1977

A new limulus assay for the detection of endotoxin.

The limulus amebocyte lysate (LAL) assay has proven to be a highly sensitive and reliable indicator of endotoxin in most biological fluids; however, it has not been a reliable indicator when used with blood because of different inhibitors present in the blood. To avoid these problems, investigators have used difficult extraction procedures, but but even with these, results were oftentimes not uniform. It was found that a recently developed inert polymer (PSI-HAP 100) has a specific affinity for endotoxin, so that is was possible to develop a simple, reliable, reproducible method for the detection of endotoxin in blood. In the assay procedure, the polymer, compressed into a 3-mm diameter bead, is incubated with 0.2 cc of heparinized whole blood. The bead is then removed from the blood, washed in pyrogen-free saline to remove any inhibitors of the LAL, and placed in a tube containing LAL. The LAL and bead are incubated together; after incubation the LAL is examined for gellation. Using this new method, it was possible to predict Gram-negative septic episodes in burn patients several days before sepsis evolved clinically.

Arthropods↗
PubMed1976

Anatomical basis for an apparent paradox concerning conduction velocities of two identified axons in Aplysia.

Larger axons usually have faster conduction velocities, lower thresholds, and larger extracellular action potentials than smaller axons. However, it has been shown that the largest fiber, R2, in the right pleurovisceral connective of the marine mollusc, Aplysia, has a higher threshold and a slower conduction velocity than does the smaller axon of cell RI, even though the amplitude of R2's spike is larger than R1's spike. One explanation of this apparent parodox is that the two axons have different "intrinsic membrane and axoplasmic constants" (Goldman, L. (1961), J. Cell Comp. Physiol. 57: 185-191). However, the deep infolding of R2's axonal membrane suggested that differences in the shape of the two axons might also account for the paradox. Accordingly, we measured the conduction velocities of the two axons and then examined the same axons in the electron microscope in order to measure their volumes and surface areas. Our morphological observations indicate that the extensive infolding of surface membrane causes R2 to have a smaller volume to surface area ratio than R1. Thus, since conduction velocity is proportional to the square root of the volume to surface area ratio (Hodgkin, A.L. (1954), J. Physiol. 125: 221-224), it is predictable that the smaller axon would have a faster conduction velocity. The results suggest that the paradoxical conduction velocities can be explained largely as resulting from differences in the shapes of the two axons. However, certain discrepancies between the measured and the predicted values suggest that other factors are contributing as well.

Animals↗