Biomedical subjects
Publications and source records attributed to G A Taylor.
In reply to Krueger, we address the issues of lowercase versus uppercase letter strings, words versus pseudowords, repeated letters in the test string, descriptions of orthographic structure, similarity effects, apples and oranges, and interactions of age with other variables.
Subcutaneous insertion of a gel-filled Silastic prosthesis to reconstruct a congenitally absent right breast was complicated by deterioration in skin circulation that necessitated removal of the implant approximately three hours postoperatively. No complications ensued when the same procedure was carried out three months later. Attention is drawn to the risk of interfering with skin circulation in patients with the rare anomaly of congenital absence of breast and nipple. The literature on this subject is reviewed. The author suggests that subpectoral implant may be a safer alternative in such cases.
Previous research has demonstrated that familiarity with the orthographic structure within a letter string can facilitate the processing of the component letters. The current research was directed at discovering the psychologically relevant properties of this structure. Two fundamental descriptions were independently varied in the construction of six-letter nonword strings. A probabilistic description based on the frequency of occurrence of letters in each position was factorially combined with a rule-governed description defined in terms of graphemic and phonological constraints. College sophomores and sixth-grade readers were asked to indicate whether or not a predesignated target letter was present in these strings. For both groups of readers, orthographic regularity and summed positional frequency were found to have only a small facilitative effect on reaction time (RT). In contrast, RTs to say "no" increased dramatically with increases in the number of letters in the catch string that were physically similar to the target letter. In another experiment, the letter string was presented for a short duration, followed immediately by masking stimulus and then the target letter. College students indicated whether or not the target was present in the test string. Accuracy of performance was critically dependent on the orthographic regularity and summed positional frequencies of the letters in the test string. No effect of letter similarity was observed. The large differences that were observed between these two tasks were accounted for in terms of the stages of processing that are critical for performance in the tasks.
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MMPI and 16 PF patterns of a group of drug abusers who were participating in a voluntary VA Drug Abuse Program were investigated. The MMPI profiles of 91 male veterans who ranged in age from 18-45 years were classified according to two-point code types. A comparison was made of the most frequently occurring code types among drug abusers, medical patients, and psychiatric patients. The two modal profile types among drug abusers were the 4-9/9-4 and the 2-4/4-2, which accounted for 32% of the sample. An additional comparison between the two modal types and responses to the 16 PF was made. Results indicate a closer resemblance to psychiatric patients than to medical patients, and the variety of high point code types is discussed. The similarity between the present sample of modal code types with research on drug abusers undertaken 20 years previously also is discussed.
Mice can be protected against the toxicity arising from lethal doses of methotrexate with purine and pyrimidine combinations, but not with pyrimidine alone. Furthermore, methotrexate treatment of tumour-bearing mice, conjunction with purine/pyrimidine protection, can be more effective than conventional metotrexate/folinic acid treatment.
Thymidine, in the absence of hypoxanthine, failed to protect normal mice from the acute toxicity of methotrexate, though tumor-bearing animals could be protected with thymidine alone, probably as a result of the availability of DNA degradation products released from drug-sensitive tumor cells. Although metrotrexate induced an early purine deficiency in gut cells, this effect was not detected in bone marrow. Later, purine deficiency became apparent in the gut and bone marrow of methotrexate-treated animals.
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Different grades of glass fibre filter paper have been compared for harvesting cells labelled with tritium using a semi-automatic harvester. Grade GF/C (Whatman Ltd) was selected for routine use although GF/B was found to be useful for whole blood cultures. The factors affecting the choice of thymidine concentration and activity are discussed and 1 mjCi or [3H]thymidine (5 Ci/mMol)/0.2 ml culture is shown to give a linear relationship with total DNA synthesis for up to 22 h.
Cytembena has been shown to undergo a rapid addition reaction with a number of thiol compounds, including glutathione and cysteine, resulting in alkylation of the sulphur. Administration of Cytembena to Yoshida sarcoma cells and to L1210 leukemia cells resulted in a loss of titratable thiol groups within the cells, though the loss of thiol groups caused by pharmacologically active doses of the drug was not sufficient to account, in itself, for the observed toxicity. The addition product of Cytembena and glutathione was isolated and tested for cytotoxicity; it was much less effective than free Cytembena. It is concluded that this reaction acts as a route of detoxification of Cytembena.
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Reconstruction for losses of the highly specialized skin on the weight-bearing and friction-resistant areas of the foot remains a challenge to the ingenuity of reconstructive surgeons. Although the use of skin from a plantar non-weight-bearing area was described by Mir y Mir 20 years ago, no other reports using the method and emphasizing its advantages have appeared in the literature. On the basis of two cases, both being failures after the use of other methods, we commend the use of a cross-instep flap.
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Citrated canine platelet rich plasma stimulated with ADP, thrombin, collagen and E. coli endotoxin demonstrated platelet aggregation when measured with Payton aggregometer. Following incubation with hydrocortisone sodium succinate (Solu-Cortef) the same platelet rich plasma did not undergo platelet aggregation when stimulated by these agents. Solu-Cortef added to platelet rich plasma during ATP, thrombin, collagen and endotoxin stimulated platelet aggregation resulted in a reversal of the optical density suggesting deaggregation. These in vitro observations support the beneficial effects observed when steroids are administered in vivo to experimental or clinical shock.
Cytembena, at low concentrations, caused an inhibition of the in vitro growth of L1210 mouse leukaemia cells which could not be reversed by reduced folates, purines, amino acids or deoxyribonucleosides. Invitro experiments with a number of enzymes of folate metabolism produced no evidence that this drug acts as an anti-folate in mammalian tumor colls. However, Cytembena, in therapeutic doses, caused a rapid and extensive inhibition of DNA biosynthesis. There was no inhibition of RNA biosynthesis, but at high doses some inhibition of protein biosynthesis was observed. Deoxyribonucleoside triphosphates accumulated in the presence of Cytembena, suggesting that the inhibition of DNA biosynthesis was at the polymerization stage. However, in vitro experiments failed to demonstrate any direct interaction of Cytmebena with either DNA or DNA polymerase.
Among fourteen patients with disruption of the thoracic esophagus, the overall mortality rate was 36%. The mortality was greatly reduced in a group of five of these patients who were treated by closed-chest tube drainage and intravenous hyperalimentation. The cause of death in most cases was sepsis and malnutrition. Although the ideal treatment in early cases of eosphageal disruption is thoracotomy and direct suture, it is believed that in patients presenting late, in old and debilitated patients, and in cases of a leaking thoracic anastomosis, the mortality will be greatly improved by the use, primarily, of conservative measures,, with the addition of intravenous hyperlimentation.