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Biomedical subjects

R St John

Publications and source records attributed to R St John.

27 records · Page 2Linked to original sources
PubMed1981

Sensitivity deficits consistent with aberrant crossed visual pathways in human albinos.

There is both anatomical and electrophysiological evidence that human albinos have abnormally crossed visual pathways. The present study examined some perceptual consequences of such pathways on the visual abilities of 12 oculocutaneous albinos and one ocular albino. Measurements were made of visual fields in all subjects. For seven subjects, contrast sensitivity functions were obtained for the central, nasal, and temporal retinas. There was a wide variation in the dimensions of the visual fields, but there was no evidence for a loss corresponding to the origin of the aberrant projections. On the basis of their contrast sensitivity functions, however, it was possible to classify the albinos into two groups. One group, with higher overall sensitivity, showed no differences between central, nasal, and temporal retina. The other group showed a marked depression in sensitivity for the temporal retina, indicating that in some albinos, information from the retinal region corresponding to the aberrant pathway is degraded.

Adult↗
PubMedDate not supplied

The prevention of venous thromboembolism: a statewide evaluation of practices in Massachusetts.

The objective of this study was to determine the proportion of Massachusetts Medicare patients who received prophylaxis for venous thromboembolism following colectomy, hysterectomy or total hip arthroplasty. The sample frame was all 90 Massachusetts acute care hospitals, and the time frame was 1 April to 30 September 1994. The patients discharged with an International Classification of Disease (ICD-9-CM) discharge diagnostic code (recorded in the Massachusetts Medicare Claims Database) for colectomy, hysterectomy or total hip arthroplasty were used to identify the target patient population. The sample population comprised 1397 patients randomly selected from the target population, including 467 total hip arthroplasties, 474 colectomies, and 456 hysterectomies. Medical records were reviewed by trained nurse abstractors who collected information on the use of prophylaxis for venous thromboembolism. Prophylaxis for venous thromboembolism was employed by surgeons practicing in Massachusetts hospitals in 93 per cent of total hip arthroplasty cases (regional variation 85-98 per cent), 84 per cent of colectomies (regional variation 57-93 per cent), 66 per cent of hysterectomies (regional variation 35-71 per cent), and in 87 per cent of the subset of 111 hysterectomies with malignancy (regional variation 25-100 per cent). The results of this statewide study demonstrated significant regional and hospital-to-hospital variation in use of prophylaxis for venous thromboembolism following major surgery. A lower rate of prophylaxis use was observed in hospitals with fewer than 200 beds and in hospitals that did not have teaching programmes. Hospitals with below-average rates of prophylaxis were targeted for intensive quality improvement interventions.

Anticoagulants↗