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Biomedical subjects

D S Feldman

Publications and source records attributed to D S Feldman.

At least 55 records · Page 3Linked to original sources
PubMed1986

Temporal lobectomy for partial complex seizures: evaluation, results, and 1-year follow-up.

Twenty-six patients were evaluated for temporal lobectomy. Fourteen underwent initial monitoring with electrodes in the amygdala and hippocampus bilaterally. Twelve had initial monitoring with scalp and sphenoidal electrodes. Four had conclusive localization without depth electrodes. Twenty-three patients underwent lobectomy. At 1-year minimum follow-up, 15 were seizure free. Five had greater than 90% reduction in seizure frequency. Complications of depth electrodes were one hemorrhage and one abscess. One patient developed impaired memory following surgery. Temporal lobectomy is effective in well-selected patients. Depth electrodes localize seizure onset from mesial temporal structures. Scalp and sphenoidal recording may be sufficient in some cases.

Adolescent↗
PubMed1985

Non-epidermally induced failure modes of percutaneous devices.

Biological spacers were used to prevent epidermally induced failure modes of percutaneous devices in dogs. The implants, however, can still fail due to infection or mechanical trauma (avulsion). The pathophysiology of these failure modes, using Dacron velour covered Silastic implants, was investigated. In view of species differences between dogs and humans, further investigations are needed before the relevance of these findings can be extended to possible clinical (human) applications.

Animals↗
PubMed1984

Construction of the annual meeting program of the Academy.

Six hundred of 912 papers submitted were accepted for presentation at the 1983 Annual Meeting of the AAN. A statistical study of scoring by individual members of the Committee showed significant mean score differences. A normalization procedure for scoring was compared with the actual meeting scores and selections. A substantial difference in 3 of 19 program categories and lesser changes in 14 others occurred. It is no longer feasible for each submission to be evaluated by all committee members. Four readers per paper and normalization of scores will result in a program reflecting the broad interests of the Academy membership.

Abstracting and Indexing↗
PubMed1983

Electron microscope investigation of soft tissue ingrowth into Dacron velour with dogs.

Electron microscopic and light microscopic analyses were performed on Dacron velour covered percutaneous devices implanted in the dorsum of canines for periods between 1 week and 9 months. The results indicated that although the capsular region around the implant was mature collagen after the 1st week of implantation, the tissue ingrowth region remained mostly immature collagen through 9 months of implantation. It appears that increasing the diameter of the fibres, which would decrease the chronic inflammatory response, and increasing the average distance between fibres should increase the amount of mature collagen between the velour fibres. In view of species differences between canines and humans, further investigations are needed before the relevancy of these findings can be extended to possible clinical applications with humans.

Animals↗
PubMed1981

The 2.5 A crystal structure of a dimeric phospholipase A2 from the venom of Crotalus atrox.

The crystal structure of the dimeric (alpha 2) phospholipase A2 from Crotalus atrox has been determined by multiple isomorphous replacement to 2.5 A resolution. A skeletal model was fit to the electron density, and the stereochemistry of the backbone was idealized. The dimeric molecule is a well defined oblate ellipsoid composed of two covalently identical subunits related by a local dyad axis which is essentially "exact" except for deviations at the periphery induced by ionic lattice contacts with neighboring dimers. As expected, the basic architecture of the individual protomers is similar to the structure of the homologous monomeric bovine enzyme (Dijkstra, B. W., Drenth, J., Kalk, K., and Vandermaalen, P. J. (1978) J. Mol. Biol. 124, 53-60). The intramolecular contact surface between the protomers is extensive and involves the catalytic and calcium-binding sites. Access to an internal cavity formed by the enclosed and abutting active center regions is quite restricted. The putative interfacial recognition surfaces of each protomer are exposed to the solvent but are on opposing surfaces of the ellipsoid, suggesting that both of these regions cannot interact with the same membrane surface simultaneously unless the membrane is distorted from planarity and/or the dimer is significantly modified.

Amino Acid Sequence↗
PubMed1977

Conjugated dihydroxy bile salt inhibition of glucose influx in rat jejunum in vitro.

Effects of bile salts on intestinal transfer differ in diverse animal preparations exposed to various bile acids. Radiolabeled glucose influx into rat jejunum in vitro was studied in buffer and compared to taurodeoxycholate, taurochenodeoxycholate, taurocholate, and deoxycholate. Jejunum was obtained from intact, bile-diverted, and colestipol-treated rats and in similar categories after abdominal x-irradiation. Taurodeoxycholate but not taurocholate inhibited glucose influx only in bile-fistula and colestipol-treated rats. Bile diversion increased and colestipol decreased glucose uptake from buffer. Added inhibitory effects of irradiation and bile salts were seen in bile-fistula animals. These data suggest that normal exposure to bile is chronically inhibiting jejunal glucose transport and that dihydroxy bile salts are responsible for this effect. They do not provide an explanation for the role of bile in the intestinal radiation syndrome.

Abdomen↗
PubMed1976

Bile salts and bioelectric properties of rat jejunum.

Addition of conjugated bile salts increased transmural- and transserosal-potential differences of sheets of rat jejunum. Removal of Cl- from buffer solutions minimized the bile-sale induced bioelectric changes. Bile-salt induced doubling of tissue resistance was not explained by an observed increase in net Cl- serosa leads to mucosa flux. Electrical effects were unrelated to concentration and were observed only when bile-salt solutions perfused the jejunal mucosa. The molecular events associated with bile-salt interactions with the plasma membrane affecting ion fluxes may relate to their unique effects on sterol absorption.

Animals↗
PubMed1975

Surfactants and bioelectric properties of rat jejunum.

The effects of surfactants on bioelectric properties of rat jejunum were determined. Tween 80 (nonionic) and sodium dodecylsulfate (anionic) increased transmural potential differences 20-34% over values in Krebs-Ringer bicarbonate buffer. Short-circuit currents increased 66-112% and net tissue resistance decreased 19-30%. The cationic surfactant cetrimide decreased transmural potential 23%; short-circuit current decreased 32%, and resistance increased 22%. When sulfate replaced chloride in buffer, surfactant effects were minimized or reversed suggesting a role of Cl- flux in the bioelectric effects. Cationic surfactant effects on current and resistance were in the same direction as, but of greater and lesser magnitude, respectively, than alterations observed with bile salts. The current increase was of greater magnitude and resistance decrease less marked. Surfactant molecules may interact specifically with membranes in a more complex manner than simple "detergency".

Animals↗
PubMed1971

Presynaptic neuromuscular inhibition by porphobilinogen and porphobilin.

The rat hemidiaphragm was studied in vitro as a test system to evaluate the effects of heme precursors and the uroporphyrins upon neuromuscular excitability. Porphobilinogen and porphobilin had no effect on the resting miniature end-plate potential frequency, but the K(+)-augmented frequency was significantly reduced. Porphobilin and porphobilinogen gave 50% of their maximal effect at concentrations of 0.008 and 0.6 mug/ml, respectively; the effect increased with concentration. Uroporphyrin I at 0.05-1.0 mug/ml caused a 25% decrease in frequency, but the effect did not increase with concentration. At similar concentrations, uroporphyrin III was without effect. The concentrations of porphobilin and porphobilinogen effective in inhibiting the K(+) stimulation, which are several orders of magnitude lower than the effective concentrations of simple amino acids, are those which might reasonably be expected in the sera of patients with acute intermittent porphyria.

Animals↗