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Biomedical subjects

A Schulman

Publications and source records attributed to A Schulman.

At least 37 records · Page 2Linked to original sources
PubMed1993

Unchanged [3H]MK-801 binding and increased [3H]flunitrazepam binding in turtle forebrain during anoxia.

In order to determine if functional changes in N-methyl-D-aspartate receptors and GABAA receptors play a role in the remarkable anoxia tolerance of freshwater turtle brain, we used autoradiographic techniques to assay [3H]MK-801 and [3H]flunitrazepam binding in turtle forebrain after turtles had been subjected to anoxia for 2 or 6 h. The effects of glutamate, glycine, competitive N-methyl-D-aspartate antagonists, glycine antagonists, polyamines, magnesium, and zinc on [3H]MK-801 binding were the same in anoxic and control turtle forebrains. These results indicate that NMDA receptor regulation plays no role in the adaptive responses to anoxia in turtle brain. In contrast, [3H]flunitrazepam binding was significantly increased in the anoxic dorsal cortex and striatum. The most parsimonious explanation for elevated benzodiazepine receptor binding is that the rise in extracellular GABA levels known to accompany anoxia enhances benzodiazepine receptor affinity. It is possible, however, that GABAA receptor upregulation during anoxia increases the effectiveness of the inhibitory action of released GABA and contributes to the anoxia tolerance of turtles.

Animals↗
PubMed1993

Intrahepatic biliary stones: imaging features and a possible relationship with ascaris lumbricoides.

Intrahepatic (IH) biliary stones are common in East Asia as part of a disease known as Oriental cholangiohepatitis (OCH). At a hospital serving non-Oriental communities, 40 patients were diagnosed on ultrasound (US) during an 8-year period as having IH stones. Follow-up showed that the diagnosis was false in three cases. In the 37 patients with IH stones, 33 conventional retrograde cholangiograms were done; 26 underestimated the IH abnormalities or missed them entirely. Computed tomography (CT) was done in 15 of these 37 patients; the attenuation of the stones was found to be only slightly above that of liver. The evidence that Ascaris lumbricoides was the cause of IH stones in our patients was that: they came mainly from communities in which A. lumbricoides infestation is virtually universal at some stage of childhood, and none from communities in which it is infrequent; their average age was younger than that of patients with conventional gall-stones, fitting with the fact that infestation is predominantly in childhood; A. lumbricoides is the only parasite in our region that invades the biliary system; the histories of the first 12 of the 37 patients had been investigated for intestinal infestation, and were all positive; and 12 of the 37 showed evidence at some time of roundworms or remnants in the biliary system, either within the US appearance of the stones ('bundles' and 'pipes') or separately on US, surgery or duodenoscopy. Biliary strictures, which occur in OCH, were not seen in our patients.

Adolescent↗
PubMed1991

A compressive strength study of complete ceramic crowns. Part II.

The original study by this group compared the crushing strength of Cerestore crowns with porcelain-fused-to-metal crowns and porcelain jackets. Since that time, two porcelains, Dicor and Renaissance, have become available. This study compares Cerestore, Dicor, and Renaissance crowns using a porcelain-fused-to-metal crown as a standard for the type of crown with maximum strength that is currently available and an all-porcelain crown to represent the porcelain with the least strength. All of the methods used in the first study were used again. The results demonstrated that these new porcelains have strengths that make them questionable for routine use in every posterior crown situation.

Aluminum Oxide↗
PubMed1991

Tarnish of dental alloys by oral microorganisms.

Five dental alloys, on exposure to blood and chocolate media with and without inoculated microorganisms, showed varying degrees of tarnish. The results indicated a composition-dependent tarnish behavior of alloys in microorganism-inoculated media, indicating a potential role for the oral microorganisms in inducing clinically observed tarnish of dental alloys. Actinomyces viscosus and periodontal pocket specimens show a similarity in their activity to induce tarnish in base metal-containing dental alloys.

Actinomyces viscosus↗
PubMed1990

Interactive effects of etching and pre-oxidation on porcelain adherence to non-precious alloys: a guided planar shear test study.

Interactive effects of etching and pre-oxidation on porcelain adherence to non-precious alloys were studied by a guided planar shear bond test under non-cantilever conditions. The results indicated that electrolytic etching decreases bond strength, but that oxidation of etched surfaces restores the bond strength level. The results are explained by a hypothesis that depletion of critical elemental species occurs during etching. Potential replenishment of the lost elements during subsequent oxidation, although not confirmed, may assist in improving bond strength.

Acid Etching, Dental↗
PubMed1990

Establishment of an implant selection protocol for predetermined success.

Previously, implant selection was confined to radiographs and to plastic implant templates for evaluation of existing bone. The aim of this study was to determine implant support areas in a compressive mode and to establish a standard via an implant selection protocol. Successful implant selection, regardless of the device design, is relevant to a patient's muscular efficiency and implant support values based on bone quality and size of prescribed bridge. The compressive areas of support, in mm2, of 15 implant designs were computer-analyzed and graph-evaluated. Major/minor diameters and the lengths of screws and cylindrical types of devices were calculated. In addition, the length, width, vents, and any lateral support areas of blade types were recorded. Average muscular force data, provided by clinical transducer studies, and literature reports of the mechanical properties of trabecular bone were correlated with computer bone analyses. These studies determined the quality of maxillary and mandibular bone to be 10 MPa and 15 MPa, respectively. Results indicated that four-unit bridges, at 50 lbs of applied force, require an area 31.14 mm2 of implant support in a compressive mode in the maxilla, and a support area of 20.76 mm2 in the mandible. Five-unit bridges require 40.84 mm2 in the maxilla and 27.23 mm2 for the mandible, because of the moment force, or torque, on the implant. Findings indicated that by determining: (1) the patient's muscular efficiency at implant sites (quantifying dynamic values of the forces and moments on implants supporting functioning bridges); (2) implant support values based on the compressive strength of the cancellous bone at implant sites; and (3) the size of the prescribed bridge, it is possible for the success (or failure) of a selected implant to be predetermined.

Alveolar Process↗
PubMed1987

The 'amputated right colon'--a diagnostic pitfall on barium enema examination. A report of 6 cases.

Six patients had strictures of the right colon not causing clinical obstruction. The strictures did not fill during barium enema tests resulting in the 'amputated' proximal right colon mimicking the caecum and/or terminal ileum. Positive caecal identification relies on terminal ileal and appendiceal filling. In 4 patients, a barium follow-through study, performed immediately after a barium enema allowed quick and safe identification of a proximal colonic stricture.

Adult↗