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Biomedical subjects

G Hunter

Publications and source records attributed to G Hunter.

At least 91 records · Page 5Linked to original sources
PubMed1977

An in vitro and in vivo analysis of anodized tantalum capacitive electrodes: corrosion response, physiology, and histology.

Oxidation-reduction reactions which can destroy high current-density metal-stimulating electrodes are avoided when using capacitive electrodes. The results of in vitro and in vivo testing of anodized, high surface area, sintered tantalum electrodes are presented. The corrosion response of the electrodes is excellent; there is no evidence of dissolution of the electrode. A deposit forms on the surface of the electrodes, but has little effect on the voltage response to constant current stimulation. The physiological and histopathological results indicate the capacitive tantalum electrode to be the safest yet tested.

Animals↗
PubMed1977

Cortical histopathology following stimulation with metallic and carbon electrodes.

Stimulation of the cat striate cortex with polished 1 mm2 gold, platinum, rhodium or carbon electrodes for 40h, at 50 Hz, and 0.5 msec duration, results in tissue damage at current densities of 0.6 A/cm2. At 0.1 A/cm2 rhodium and carbon were toxic to brain. In vitro gold and platinum corroded after 1,500-2,300 h of testing in simulated cerebrospinal fluid. The materials utilized are not suitable for long-term chronic electrodes for neural prosthetics.

Animals↗
PubMed1977

The natural history of the patient with an infected total hip replacement.

Deep infection, the most serious local complication of total hip replacement, prompted a study of the records of 135 patients (137 hips) thus afflicted in a nationwide survey of Canada. Particular attention has been paid to the natural history of the infection, and the problems of diagnosis are described. Twenty-one patients died after the insertion, or removal, of the prosthesis, and of the survivors of the original 135 patients only eighteen have been able to retain the prosthesis without further problems with the wound. The remaining patients had the prosthesis removed, and most dry wounds. Certain suggestions are made on management. The advice that a second total hip prosthesis should be inserted after a deep infection of the first implant is not supported.

Aged↗
PubMed1976

The results of prosthetic replacement in fracture-dislocations of the upper end of the humerus.

Eleven patients with fracture-dislocation of the upper end of the humerus treated by a Neer prosthesis are reviewed. The results of treatment are very disappointing. The complication rate is high. From these results in a small series, it would appear that prosthetic replacement of the humeral head does not offer the patient any significant advantage when compared with other reported methods. The possible cause of these poor results are discussed.

Aged↗
PubMed1976

Access to health care in a southern rural community.

This case study of utilization of health care services in a rural southern community is the first of a series of reports dealing with access to care in this community. The most striking findings were the low utilization of physician and dental services compared with national standards (particularly by the black population) and the infrequent use of private physicians by blacks. Possible explanations for these findings are the short time interval since integration of services after Medicare and Medicaid legislation, the short supply of primary care physicians, especially black, in this community, and the reluctance of white physicians to accept Medicaid patients. We postulate that while employment and social mobility have improved greatly for blacks, established methods of medical and dental practice have changed slowly.

Adolescent↗
PubMed1974

Nascent DNA synthesis in ultraviolet light-irradiated mouse, human and Chinese hamster cells.

The technique of alkaline sucrose gradient centrifugation was used to study newly synthesized DNA in control and ultraviolet light-irradiated mouse L, human HeLa, and Chinese hamster ovary cells. Nascent DNA molecular weight distributions did not appear to differ among the three cell lines for unirradiated cells. However, at short times after ultraviolet light irradiation, human HeLa cells appeared to synthesize more low molecular weight DNA than either mouse L or Chinese hamster ovary cells. Since this difference was not related to differences in either the rate of DNA synthesis or amount of ultraviolet damage in the irradiated cells it appeared to be a phenotypic characteristic of the cell lines tested. A parallel was noted for these three cell lines between an increase in the synthesis of low molecular weight DNA, detected on alkaline sucrose gradients, and cell killing as measured by the ability of irradiated cells to form colonies.

Animals↗
PubMed1974

Non-histone chromosomal proteins. Evidence for their role in mediating the binding of histones to deoxyribonucleic acid during the cell cycle.

By selective dissociation of histones with the ionic detergent sodium deoxycholate, we have demonstrated that these basic chromosomal polypeptides, which are effective inhibitors of transcription, are more tenaciously bound to DNA in mitotic than in S-phase chromatin. Evidence is presented which suggests that cell-cycle-stage-specific non-histone chromosomal proteins can account for such variations in the association of histones with DNA. When chromatin is reconstituted with DNA and histones are pooled from S-phase and mitotic cells and either S-phase or mitotic non-histone chromosomal proteins, a preferential extraction of histones with sodium deoxycholate from chromatin reconstituted with S-phase rather than mitotic non-histone chromosomal proteins is observed. In contrast, the extractability of histones with sodium deoxycholate from nucleohistone complexes reconstituted with DNA pooled from S-phase and mitotic cells and either S-phase or mitotic histones is identical. Since non-histone chromosomal proteins rather than histones are responsible for the differences in chromatin template activity during S-phase and mitosis, we propose that non-histone chromosomal proteins may modify gene expression during the cell cycle by mediating the binding of histones to DNA.

Binding Sites↗