Biomedical subjects
Publications and source records attributed to R James.
A case report of fatal ingestion of mevinphos with several points of interest: There was a known ingested dosage of 28 g. Several observers witnessed events from ingestion to death. Death was rapid--apparently within 1 min and certainly within 14 min.
Cervical diastematomyelia is a very rare entity. We present a case in a 20-yr-old girl, associated with anomalous bone in the neck.
Envenoming by a number of species of snake may affect the myocardium or cause electrocardiographic changes; several different mechanisms have been proposed. In a prospective study of snake bite in Papua New Guinea, electrocardiographic changes were observed in 36 of 69 patients (52%) envenomed by the taipan (Oxyuranus scutellatus), 2 of 6 (33%) envenomed by death adders (Acanthophis sp.) and one envenomed by the brown snake (Pseudonaja textilis). Septal T wave inversion and bradycardias, including atrioventricular block, were the commonest abnormalities. There was no haemodynamic deterioration. The cause of these changes is uncertain; only 2 of 24 patients (8.3%) with electrocardiographic changes had markedly elevated plasma concentrations of cardiac troponin T, a sensitive and specific marker of myocardial damage. This suggests that myocardial damage is uncommon following bites by these species. Electrocardiographic abnormalities are most likely to have been caused by a direct toxic effect of a venom component upon cardiac myocyte function; in taipan bites, taicatoxin, a calcium channel blocker, might be responsible.
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Some DDT analogs are estrogenic, particularly o,p'-DDT, which comprises approximately 15-20% of the commercial DDT mixture. Whether this compound or its metabolites are active has not been established. In fact, the data obtained thus far are more confusing than enlightening. For example, CCl4 pretreatment of immature female rats has been reported to inhibit or enhance estrogenic activity of o,p'-DDT, and SKF-525A pretreatment has been reported to enhance or not alter the estrogenic effect. Although o,p'-DDT inhibits binding of estradiol to the estrogen receptor from rat or human at low levels (approximately 1-10 micrometer) in vitro, higher levels are required to inhibit nuclear binding of [3H] estradiol in incubated whole uteri. Futhermore, o,p'-DDT appears to be neither estrogenic nor antiestrogenic in an in vitro estrogen assay. Methoxychlor appears to be "activated" by metabolism, and it is probable that phenolic metabolites are responsible for its estrogenic activity. Since chlorinated hydrocarbons often enhance the metabolism of steroids and may reduce circulating levels of steroids, interactions of the exogenous hormonally active agents with steroid receptors may be self-potentiating in vivo.
Metallic objects are a well known source of artifact in magnetic resonance imaging. We report a case of artifacts created by metallic fibers woven into surgical scrub pants worn by a patient during the examination.
Water quality is one of the most important aspects of ensuring a safe and effective delivery of haemodialysis. An extensive microbiological survey of several water systems highlighted a contamination problem which routine sampling had failed to detect. Current guidelines suggest that samples for microbiological and endotoxin analysis should be taken from the outlet of water treatment plant and points expected to have the highest bacterial load, normally the end of the distribution loop and connections to the dialysis machines, where the flow is at its lowest. The survey extended sampling to include a large number of machine connection points. Four systems were investigated. The samples from routine test points generally returned results within our operational limits (<10 CFU/ml and <0.06 IU/ml). However, results from several machine connection points exceeded these limits by a large margin. Several disinfection cycles were required in order to achieve results in keeping with our operational limits. The conclusion is that sample results from the end of the distribution loop may give a false sense of security by not indicating a contamination problem at the machine connection points. Increasing the number and frequency of machine connection points tested should provide greater security in detecting contamination and allow for remedial action at an earlier stage.
Working within the multi-professional team, renal technicians play a greater part in the functioning of renal units than in other less technical areas of care. The role of the renal technician has been changing and, is now one that often combines technical, scientific and clinical knowledge in utilizing technology so that the long-term outcomes of the patient are optimised and complications reduced. Therefore a sound knowledge base is vital in ensuring patients' safety. Whilst still centered on the traditional engineering functions such as equipment repair and maintenance, the curriculum is structured to give a broad overview of renal related physiology, chemistry, treatment modalities and technology. The inclusion of these more clinical aspects in the curriculum reflects the change in the technician's role to a more science-based approach.
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In the face of public expectation of uniformly high standards of medical practice and of open accountability, we suggest that the public interest would be served by a system of transparent, informed and independent scrutiny of those deaths that follow medical treatment, either in hospital or in the community. We do not believe that such a system operates at present in England and Wales or, indeed, that best practice may be achieved within current financial or legislative constraints. However, we suggest that the existing law allows greater involvement of the coroner in the investigation of deaths following medical treatment, should there be the professional desire for self-scrutiny and the political will to release resources to support that desire.
We analyzed the MR findings of five patients with benign intracranial epithelial tumors, commonly called epidermoids. The neoplasms were categorized into two groups on the basis of T1-weighted MR signal intensity (relative to brain): high-signal-intensity masses (short T1) and low-signal-intensity masses (long T1). Surgical specimens were obtained and analyzed by means of 13C MR spectroscopy. Epidermoids with short T1 values (white epidermoids) had a high lipid content comprising mixed triglycerides containing unsaturated fatty acid residues. Epidermoids with long T1 values (black epidermoids) exhibited a much reduced lipid content with no triglycerides or fatty acids. There was evidence of trace amounts of cholesterol in the black epidermoids. Our data indicate that epidermoids are a heterogeneous group of neoplasms that behave differently with T1-weighted MR imaging and 13C MR spectroscopy. The combination of MR imaging and spectroscopy holds the potential of further elucidating the nature of epidermoids as well as of other forms of neoplasms.
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The influence of the S- and R-enantiomers of normephenytoin on various hepatic drug-metabolizing enzyme systems has been investigated in the rat. Both enantiomers proved to be potent enzyme inducers. In vivo, 14C-aminopyrine breath test half-life was decreased and 24-hr urine recovery of 14C after 14C-diphenylhydantoin administration was increased. In vitro, hepatic cytochrome P-450 concentration was increased and there were increases in activity of oxidative metabolism of aminopyrine, aniline, hexobarbital, and p-nitroanisole, and in activities of glucuronyltransferase and glutathionetransferase enzymes. There were differences in the disposition of R- and S-enantiomers indicating that (S)-normephenytoin was eliminated more rapidly. Taking this into consideration, the two enantiomers were equipotent enzyme-inducing agents.
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