Biomedical subjects
Publications and source records attributed to A Malcolm.
Inflammatory, symmetrical peripheral polyarthritis is observed in a small proportion of patients following a variety of parasitic, viral and microbial infections. The development of such a post-infective arthritis disorder may depend on a sequence of events, which need not be confined to one extrinsic pathogenic organism.
Ribosomal proteins from Escherichia coli have been isolated by a mild purification procedure. Their tertiary structure has been explored by two techniques, proton magnetic resonance and limited proteolysis. A number of proteins when subjected to limited proteolysis produce resistant fragments in good yields. In most cases this does not depend on the specificity of the enzyme used. The proteins S15, S16, S17 and L30 are not degraded at all, whereas a few proteins are very susceptible to proteolysis. 1H-NMR experiments show that the majority of the ribosomal proteins have a uniquely folded tertiary structure. This is particularly pronounced in the four proteins mentioned above which resist proteolysis. In general, a good agreement is observed between the degree of proteolytic resistance and the amount of folding indicated by NMR spectroscopy. Similar studies on a few ribosomal proteins purified under denaturing conditions show that, in contrast, these protein preparations are not structurally homogeneous and that they contain a mixture of denatured and renatured molecules. The results are interpreted in terms of a compactly folded tertiary structure for the four proteinase-resistant proteins while the majority of the other proteins appear to have two domains, one compactly folded and resistant to proteinase and the other flexible and susceptible to proteolysis. A few proteins seem to have a completely flexible structure and can therefore be easily degraded.
The purpose of this present investigation was to determine if the presence of exogenous nutrients constitutes a prerequisite for acid modification of thermal damage and to determine if thermal cytotoxicity is affected by nutrient availability under acid conditions. To this end, Chinese hamster ovary cells (CHO) were heated (42 degrees or 43 degrees C) and/or irradiated in either McCoy's medium containing 10% fetal bovine serum or glucose free Hanks Balanced Salt Solution (HBSS). Both thermal sensitivity and thermal radiosensitization were increased when CHO cells were treated under acid conditions (e.g., pH 6.8) compared to alkaline conditions (e.g., pH 7.2), independent of the media used. Furthermore, decreasing nutrient availability increased thermal cytotoxicity, but the increase was greatest at pH 7.2 compared to pH 6.8. This study indicates that thermal sensitivity is more dependent upon pH than upon nutrient availability.
A chemotherapy combination of cyclophosphamide, doxorubicin, and cisplatin (CAP) was administered to 30 patients with stage III M0 or M1 (supraclavicular nodes) unresectable non-small cell lung cancer before and after radiotherapy. All patients had mediastinal metastases and most had T2 or T3 primary lesions. The response rate (complete plus partial) after two cycles of CAP was 47%, which increased to 66% (24% complete response rate) following radiotherapy. The overall median survival from initiation of chemotherapy was 9 months. CNS relapse occurred in five (26%) of 19 responding patients who did not receive prophylactic cranial irradiation in the early part of the study.
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Seventeen patients with advanced ovarian carcinoma who had minimal residual intraabdominal disease after six months of combination chemotherapy were treated with abdominopelvic irradiation. All 17 patients had residual intraabdominal tumor nodules with a cross-sectional diameter of less than 2 cm. Eleven had only microscopic residual disease at the time of irradiation. Fourteen have relapsed at a median of eight months after the completion of radiotherapy. All but two had intraabdominal recurrences. Myelosuppression was common and severe, causing marked delays or discontinuation of radiotherapy in ten of 17 patients. Patients receiving the entire planned dose of radiotherapy had longer disease-free survival (14 months median) than did patients receiving only partial doses (seven months median). However, six of seven patients receiving full dose irradiation have relapsed. Abdominopelvic irradiation in the schedule employed here is poorly tolerated and is not an effective salvage treatment in patients with limited or microscopic residual tumor following initial combination chemotherapy.
Thyroid lymphocytes from Graves' and Hashimoto patients have been investigated and compared with lymphocytes from the peripheral blood. Considerably more lymphocytes (20-30 X 10(6)/g) could be isolated from Hashimoto thyroids than from Graves' tissue (1-5 X 10(6)/g) but the cell suspensions extracted from Hashimoto and Graves' glands were similar in terms of cell surface markers and the ability to synthesize immunoglobulin. Thyroid lymphocytes contained a lower proportion of T cells (OKT3+ cells) and in some cases more B cells than the peripheral blood but the ratio of helper to suppressor T cells (OKT4+:OKT8+ cells) was similar to the values obtained for blood lymphocytes. Further, thyroid lymphocytes (unlike blood lymphocytes) synthesized relatively large amounts of microsomal and/or thyroglobulin antibody when cultured in medium only and these levels were significantly decreased by the addition of pokeweed mitogen. The results of this study provide further evidence for the role of the thyroid as a major site of thyroid autoantibody synthesis and emphasize the importance of characterizing the cells infiltrating the gland in autoimmune thyroid disease.
To examine the effect of platelet-active drugs on the spread of blood-borne tumour cells, two murine tumours, sarcoma 180 (S-180) and TLX-5 lymphoma, were selected. Following intravenous (IV) injection into CBA mice the former elicited thrombocytopenia and formed discrete pulmonary tumours, whereas the latter failed to elicit thrombocytopenia and formed discrete tumours in all visceral organs examined except the lungs. S-180 cells were injected IV into mice pre-treated with RA233 (known to prevent thrombocytopenia and thrombus formation) and TLX-5 cells were injected IV into mice pre-treated with Corynebacterium parvum (known to induce thrombocytopenia and thrombus formation). RA233 pre-treatment did not change survival time or incidence of S-180 pulmonary tumours but did result in a higher incidence of extrapulmonary tumours and a lower tumour cell burden immediately after injection. Pre-treatment with C. parvum resulted in a higher TLX-5 tumour cell burden but not discrete tumours in the lungs. On the basis of known drug activities it is proposed that thrombocytopenia induced in these experiments is in part a reflection of thrombus formation in the lungs which influences the speed of passage of tumour cells through capillaries. In some cases this may lead to a changed anatomical distribution of tumour lesions.
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Sixteen patients with metastatic disease to the liver (12 colorectal and four unknown primary tumors) were treated in a pilot study of hepatic irradiation (2500-3000 rads in 10-12 fractions) delivered concomitantly with continuous short-term intraarterial infusion of 5-fluorouracil (1 g/d) or FUDR (0.5 mg/kg/d) via a percutaneously placed hepatic artery catheter. Abnormal liver function tests, including SGOT, LDH, and alkaline phosphatase, decreased in all patients by day 7-10 of treatment, and other metabolic factors, including serum cholesterol, calcium, albumin, phosphorous, and uric acid, also decreased, often to subnormal levels by termination of treatment (day 15-20). These chemical alterations did not correlate with tumor response in that the identical pattern was observed in responders (ten patients) as well as nonresponders (six patients). Objective determinants of response were assessed by serial monitoring of the plasma carcinoembryonic antigen (CEA) and liver scan. In 14 patients with elevated CEA levels, tumor response (nine patients), nonresponse (four patients), and relapse (five patients) was predicted and confirmed by sequential monitoring of CEA. In one patient, a paradoxical decrease in plasma CEA was associated with progressive disease. The liver scan identified all responding patients but was difficult to quantitate and was delayed for months following subjective clinical response and changes in plasma CEA levels.
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Debate continues as to whether the differing shapes of the acromion are congenital or acquired. This has been investigated by neonatal cadaver study, adult cadaver study, radiographic study, magnetic resonance imaging study, or various other means. No one, to our knowledge, has investigated this by histologic study. A macroscopic and histologic study of 22 cadaveric shoulder joints was carried out to establish what, if any, developmental changes occur in the differing patterns of acromion. The cadaveric shoulders were dissected and examined macroscopically. All of the acromion processes were transected and photographed, and the histology of the anterior and inferior surfaces was studied. In all of the curved and hooked types of acromion, a common pattern of degeneration of collagen, fibrocartilage, and bone was observed, consistent with a traction phenomenon. None of the flat acromions exhibited these changes. Extensive histologic changes were noted on the anterior surface of acromion as compared to the inferior surface in curved or hooked acromion. We conclude that the different shapes of acromion are, therefore, acquired as a response to traction forces applied via the coracoacromial ligament and are not congenital in origin.