Biomedical subjects
Publications and source records attributed to R Plante.
This note compares the substrate specificity of D-lactate dehydrogenase (D-LDH, EC 1.1.1.28) to that of L-lactate dehydrogenase (L-LDH, EC 1.1.1.27), illustrates three procedures that use D-LDH in synthesis and two methods for recycling NADH, and provides experimental details illustrating the use of D-LDH in organic synthesis.
This article details the problems related to occlusion of 13-14 year old Quebec students. The data was derived from a province wide probability sample of 1201 children in 1983-84 using Granger's Orthodontic Treatment Priority Index (TPI). The principal conclusion are: 32% of the children are in Angle's class II; 18% have an overjet of 5 mm and over; 50% have one or more teeth in minor or major displacement; treatment is mandatory or highly desirable for 13.7% and only 2.9% of the students are under treatment. The results are compared to 6 surveys of the same nature.
Reliability and ease of use are certainly the two major qualities of a screening test or medical surveillance in the workplace. The advantages of using a reliable urinary test thus are evident: the sampling is easy, rapid, noninvasive and, therefore, well accepted. Screening tests or medical surveillance can measure the toxic chemical itself, its metabolites or its consequences on metabolism. In this study the relation between blood lead levels--the most commonly used test for screening and surveillance of saturnism--and urinary excretion of delta-aminolevulinic acid (ALA-U) was measured. The original part of this study is that it takes into account the chronobiology of ALA-U excretion. The samples are collected in the afternoon when ALA urinary excretion is at its highest level. Using a 5 mg/g of creatinine level as a threshold to detect blood lead levels equal to or higher than 60 micrograms/dL the test has an 88% sensitivity, a 91% specificity and a 37% positive predictive value. No worker whose blood lead level is equal to or higher than 65 micrograms/dL has been missed. It is suggested that using 5 mg of ALA-U/g of creatinine as a threshold to prescreen workers who should have their blood lead level measured could be useful in workplaces where lead exposure is moderate or low.
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Seven drinking water treatment plants were sampled twice a month for 12 months to evaluate the removal of indicator bacteria and cytopathogenic enteric viruses. Samples were obtained at each level of treatment: raw water, postchlorination, postsedimentation, postfiltration, postozonation, and finished (tap) water. Raw water quality was usually poor, with total coliform counts exceeding 105 to 106 CFU/liter and the average virus count in raw water of 3.3 most probable number of cytopathogenic units (MPNCU)/liter; several samples contained more than 100 MPNCU/liter. All plants distributed finished water that was essentially free of indicator bacteria as judged by analysis of 1 liter for total coliforms, fecal coliforms, fecal streptococci, coagulase-positive staphylococci, and Pseudomonas aeruginosa. The total plate counts at 20 and 35 degrees C were also evaluated as a measure of the total microbial population and were usually very low. Viruses were detected in 7% (11 of 155) of the finished water samples (1,000 liters) at an average density of 0.0006 MPNCU/liter the highest virus density measured being 0.2 MPNCU/liter. The average cumulative virus reduction was 95.15% after sedimentation and 99.97% after filtration and did not significantly decrease after ozonation or final chlorination. The viruses isolated from treated waters were all enteroviruses: poliovirus types 1, 2, and 3, coxsackievirus types B3, B4, and B5, echovirus type 7, and untyped picornaviruses.
Carotid fibromuscular dysplasia (FMD-C), a stenosing angiopathy, is frequently associated with pulsatile tinnitus. This study reports two patients, initially presenting with pulsatile tinnitus, who proved to have FMD-C. Symptoms such as tinnitus, vertigo, hemicrania, and cervicofacial hypo-esthesia might bring such a patient under an otolaryngologist's management. The paper discusses the physiopathology of the symptoms encountered with FMD-C. It is suggested that the sympathetic plexus is implicated in the manifestations of the disorder. A surgical therapeutic approach is suggested to achieve satisfactory symptomatic control.
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We have used the paradoxical antigonadal effects of LHRH agonists as a chemical castration in advanced prostatic cancer. We report early results of a phase II study on the clinical efficacy of the LHRH agonist D-Ser (TBU)6, des-Gly-NH2(10) LHRH administered to patients with stage D prostatic carcinoma. Following dose-range finding studies using either intranasal (IN) (200 micrograms twice/day or 500 micrograms twice/day) or subcutaneous (SC) administration (50 micrograms once/day, we developed a sequential combination of SC (500 micrograms three times/day for seven days) and IN regimen that was administered for 3 to 16 months to a group of 23 patients with stage D prostatic carcinoma. Initiation of therapy was associated with a clinical flare in one patient during the first week of treatment. Mean serum testosterone levels were already decreasing at one week and remained inhibited to levels inferior to 1 ng/ml after the first four weeks of treatment. Overall assessment shows that within the first six months of treatment, 26% patients were improved, 39% were stabilized, and 35% were nonresponders. Fourteen patients were followed during the next six months: 29% continued to respond, 29% escaped, 21% remained stable, and 21% were nonresponders. Histologic studies from castrated patients showed changes in spermatogenesis correlating to the degree and duration of suppression of testicular steroidogenesis without signs of toxicity. Preliminary observations on the combination of the pure antiandrogen RU 23908 with Buserelin (n = 5) or castration (n = 3) suggest that the addition of an antiandrogen does not seem to improve the patients nonresponding to other hormonal suppressive therapy (Buserelin) administered before (n = 3) or concomitantly with the antiandrogen (n = 2). Three relapsing castrate patients responded to the antiandrogen, but the response was temporary in two (eight to nine months of therapy). No side effects other than hot flashes and decreased potency are related to LHRH agonist alone or to the low-dose antiandrogen. Multicenter trials will be necessary to delineate the place of LHRH agonist alone or LHRH agonist combined with an antiandrogen in the treatment of prostatic cancer.
Two juvenile size silicone testicular prostheses were analyzed following replacement by adult size devices after 72 and 99 months in situ. Scanning electron microscopy and electron microprobe studies were carried out on the explanted silicone prostheses and their attached tissue capsules. The material at the surface of the prostheses gave no evidence of biodeterioration. However, localized sites of calcification were observed. The adjacent tissue capsule consisted of two distinct concentric layers with different morphologies; the one adjacent to the prosthesis consisted of dense arrays of collagen fibres oriented parallel to the silicone surface and extending outward to a thickness of 100-120 microns. The outer layer was less dense, more disordered and was uneven in thickness. It contained numerous discrete particles of silicon-rich material. Technical and clinical implications of these results are discussed.
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