Biomedical subjects
Publications and source records attributed to P Allain.
On the basis of two cases, the problem is raised of the pathogenesis of kerato-cysts. The possibility of some sort of "induction" by factors which are involved in provoking eruption of the teeth is suggested by the clinical cases described.
We used two methods of reversed-phase liquid chromatography with amperometric detection, one for assay of unconjugated norepinephrine, epinephrine, and dopamine in urine, the other for determination of unconjugated vanillylmandelic acid and homovanillic acid. The catecholamines were extracted from urine by passage through a weak-cation exchange resin, then through alumina. Vanillylmandelic acid and homovanillic acid were isolated from urine by a two-step solvent-extraction procedure. The between-day CV was 5% for norepinephrine, 3% for epinephrine, 3% for dopamine, 4.5% for vanillylmandelic acid, and 6.4% for homovanillic acid. Reference ranges for these analytes in 76 children, ages 3-16 years, are reported.
Thiopental was used in long-term infusion (3-4.5 mg . kg-1 . h-1 during 4-8 days) to protect the brain from injury following trauma. Thiopental plasma concentrations were measured during infusion (48 patients) and after infusion (14 patients) to determine the kinetics of the drug in continuous infusion. All mean values were mean +/- SD. Steady state concentrations (Css) were 31.8 +/- 10.7 mg/l for an infusion rate of 3.05 +/- 0.37 mg . kg-1 . h-1 and 48.9 +/- 14.6 mg/l for a rate of 4.2 +/- 0.3 mg . kg-1 . h-1. Corresponding steady state clearance decreased when Css increased, indicating possible saturation of the metabolic enzymatic system. Michaelis-Menten kinetics were confirmed by postinfusion data that give, for higher Css, a nonlinear decay of log C versus time. First-order kinetics were only obtained with Css below 30 mg/l. The maximum rate of elimination (Vm) was 1.76 +/- 1.15 mg . l-1 . h-1 (n = 11), and the Michaelis constant (Km) was 26.7 +/- 22.9 mg/l (n = 11). Hepatic enzyme saturation was between 35 and 85%. The volume of distribution at steady state was 4.35 +/- 1.83 l/kg (n = 11). Apparent half-lives of elimination were between 18 and 36 h at the end of infusion, and predicted terminal half-lives were 10.15 +/- 5.43 h (n = 11). Phases of burst-suppression were observed on electroencephalographic traces for concentrations greater than 40 mg/l. The authors' results suggest that a continuous infusion at a dose of 4 mg . kg-1 . h-1 induces EEG changes consistent with a near-maximum reduction in cerebral metabolism. Because of the thiopental Michaelis-Menten kinetics at doses above 4 mg . kg-1 . h-1, the authors suggest that thiopental plasma concentrations be measured and/or the drug effect be measured with the EEG to prevent excessive thiopental overdosage, causing a prolonged recovery time.
A clinical study was conducted during the postoperative period in adolescents to compare efficacy of two regimens by objective (temperature, edema) and subjective (pain) criteria. half had received preoperative immunotherapy and the other half conventional postoperative antibiotic treatment. Operations were germectomy of a wisdom tooth and maxillary osteotomy. Results were submitted to statistical analysis and data obtained from the objective and particularly subjective parameters studied led to the routine introduction of preoperative immunotherapy for these operations.
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In six anuric haemodialysed patients, aluminium and iron mass transfer were determined 48 hours after 40 and 80mg/kg body weight desferrioxamine intravenous infusion. All patients were aluminium overloaded (mean +/- SEM: 2.91 +/- 1.05 mumol/g wet tissue bone) and two had high plasma ferritin. Haemodialysis and haemofiltration were performed using a highly permeable membrane. The adequate dose of desferrioxamine for aluminium removal is 40mg/kg, since aluminium mass transfer induced by haemodialysis and haemofiltration (47.4 and 40 mumol/session) are not significantly different from that obtained with 80mg/kg. Iron removal is dose related in high plasma ferritin concentration patients: 50 and 100 mumol/session with haemodialysis and 29 and 175 mumol/session with haemofiltration after 40 and 80mg/kg body weight respectively.
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Rubidium concentrations were measured by flame emission spectrophotometry in whole blood, plasma and red cells from male and female controls and from dialyzed and non-dialyzed patients of both sexes with chronic renal failure. Rubidium concentrations (mumol/l) in male and female controls respectively were: 2.29 +/- 0.29 and 1.96 +/- 0.46 in plasma: 36..79 +/- 5.90 and 30.19 +/- 6.11 in whole blood; 74.57 +/- 10.37 and 72.22 +/- 12.76 in erythrocytes. The red cell rubidium/plasma rubidium ratios were 32.6 in males and 38.3 in females. Compared with controls, dialyzed male and female patients showed, before dialysis, a decrease in rubidium concentrations of respectively -30% and -17% in plasma, -64% and -61% in whole blood, -40% and -33% in erythrocytes. A further decrease of 25% in rubidium plasma concentrations was observed after dialysis. Non dialyzed patients had an increase in plasma concentrations (+14% in males, +23% in females) and a decrease in erythrocyte concentrations (-16% in males, -20% in females) as compared with controls. Our data show that plasma and red cell rubidium concentrations are fairly constant and probably regulated in healthy subjects but vary considerably in patients with renal failure.
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A comparative study of the Cu2+ effects, binding and reduction, has been performed on rat liver mitochondria. In the first minutes, Cu2+ (less than or equal to 50 micron) is massively bound and reduced to the extent of 70%-80% while a simultaneous activation of respiration takes place. Then the remaining 20% or so of Cu2+ are progressively bound and reduced while respiratory inhibition, Ca2+ and Mg2+ effluxes, and swelling are observed. EDTA, used as a copper chelator, prevents or reduces the copper effects and removes part of the bound copper, according to the time of introduction in the incubation medium after Cu2+. The results suggest that the two steps of the copper binding and the effects following involve mainly first the outer (cytosol side) proteins of the inner membrane and then those of the inner membrane. 100 microM dithiothreitol and 100 microM glutathione used as antioxidant thiol reagents prevent, as does EDTA, but do not reverse the 25 microM copper effects. They also decrease the copper binding; however, no relationship between binding and preventive action is observed. It is shown that glutathione and dithiothreitol have a specific potent ability to reduce Cu2+, which explains that in presence of these reagents copper may react with mitochondria partly or entirely in the form of Cu+. These findings suggest that Cu2+ in its Cu+ form has no mitochondrial effect. A mechanism of copper action involving oxidation of some membrane thiol groups is discussed.
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Plasma noradrenaline (NA) and adrenaline (A) concentrations were measured by high liquid pressure chromatography in five untrained subjects and in five well-trained rowers during an exercise test on bicycle ergometer. Blood samples were collected, via a venous catheter, at rest, after standing 5 minutes, at maximal work level and at 5, 10, 20 minutes of post-exercise. Plasma NA and A concentrations at rest and after 5 minutes of standing were similar in the two groups. At maximal work load (340 +/- 38 for rowers and 220 +/- 11 W for untrained subjects), for a same pulse rate (178.0 +/- 7.6 for rowers and 176.6 +/- 4.7 beats/minutes-1 for untrained subjects), NA and A concentrations were higher in athletes (NA: 5.57 +/- 1.32 microgram/l; A: 0.95 +/- 0.31 microgram/l) than in untrained subjects (NA: 2.13 +/- 0.80 microgram/l; A: 0.40 +/- 0,34 microgram/l). During recovery, no significant difference was observed between the two groups.
A method for the plasma noradrenaline (NA) analysis by reversed-phase liquid chromatography with electrochemical detection is described. The plasma sample preparation includes two-steps: ion-exchange and alumina adsorption. The use of a data system and an automatic sampler enables the injection of samples in series. Using this technique, determination of plasma NA concentration in 34 healthy subjects (27.4 +/- 7.2 years) gave the following results: 0.28 +/- 0.10 micrograms/l after 30 min of resting in the supine position and 0.52 +/- 0.17 micrograms/l after 5 min of upright position.
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Stomatologists well know that phenotype can reproduce a lot of abnormal genotype aspects, in facial growth. These vitiations are bound to abnormal behaviours during such functions as: deglutition, breathing, oral expression. It is important to know if "wrong para-functions" adopted in such praxies are psychologically significant. Very often, the psychiatrist only, will be able to confirm or oppose contra-indication about the surgical treatment of facial abnormalities in such special cases, known or unknown.