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Biomedical subjects

C Michel

Publications and source records attributed to C Michel.

At least 253 records · Page 14Linked to original sources
PubMed1990

Use of the biochemical analysis of muscle proteins to help the classification of polychromic individuals of the genus Symphodus.

Among Labrid fishes (Wrasses), polychromy is very frequent. Indeed, a few species of Symphodus show individuals with a peculiar colouration. On one hand, electrophoretic analysis of muscular proteins (myosin and parvalbumins) reveals no differences between the normal individuals and the coloured morphs of the three species. On the other hand, these analyses display disparities between fishes of the two subgenus (Crenilabrus and Symphodus). Biochemical characters seem to have evolved in the same way that morphological and behavioural ones: the subspecies based only on differences in colouration are not confirmed but the differences between subgenus are revealed.

Animals↗
PubMed1990

Characterization of Cat-2t, a radiation-induced dominant cataract mutation in mice.

A dominant cataract mutation was detected recently among the offspring of x-ray-irradiated male mice. The mutation, which causes total lens opacity, has provisionally been designated by the gene symbol Cat-2t. In the lenses of heterozygous and homozygous Cat-2t mutants, the epithelial and fiber cells were swollen and the lens capsule was ruptured. The histologic analysis demonstrated a complete destruction of the cellular organization of the lens, which might be caused by its altered developmental processes. The data derived from biochemical investigations indicate that biochemistry of the cataractous Cat-2t lenses is affected: the osmotic state as indicated by the increased water content and increased Na(+)-K(+)-adenosinetriphosphatase (ATPase) activity; the energy state as indicated by the decreased adenosine triphosphate (ATP) concentration; and the redox state as indicated by the enhanced content of oxidized glutathione. Additionally, the lenticular protein composition is altered because of the presence of vimentin in the water-soluble fraction. This cannot be explained by the enhanced crosslinking activity of transglutaminase. The changes of the osmotic, energy, and redox states are considered to be secondary in relation to the altered lenticular development. In contrast, the variations concerning vimentin and transglutaminase might be a biochemical indication of the changed development. Possible similarities to other dominantly expressed murine cataract mutants are discussed.

Adenosine Triphosphate↗
PubMed1990

[Is peritoneal dialysis adequate in the treatment of terminal uremia in aged patients].

In Europe and in the United States, the elderly comprise an increasing segment of the end-stage renal disease population on chronic dialysis. Based on our own experience (84 patients over 75 years treated by PD between 1983 and 1990), the aim of the study was to analyze the advantages and disadvantages of peritoneal dialysis (PD). There are many benefits of PD for elderly patients including less hemodynamic stress than hemodialysis, no need for a vascular access, increased mobility and sense of control over illness, maintenance of residual diuresis. Increasing experience in geriatric PD leads to a better control of problems which may affect the outcome of PD (inability to perform self-dialysis, nutritional abnormalities, peritonitis, bowel dysfunction). PD appears to be an acceptable form of renal replacement therapy in the elderly.

Aged↗
PubMed1990

[Circumscribed spinal myositis ossificans of infections origin].

A case of paravertebral, non-traumatic myositis ossificans in a 4.5 year-old boy is reported. Infectious spondylitis and osteosarcoma were considered before the diagnosis was established on the basis of histological examinations of a biopsy performed during excision. A group G beta hemolytic streptococcus was isolated from the biopsy, suggesting an infectious etiology which has rarely been reported. The child appears to be completely cured one year after excision.

Child, Preschool↗
PubMed1990

A concurrent increasing of natural antibodies and enhancement of resistance to furunculosis in rainbow trout.

In order to compare the respective roles of specific response and non-specific mechanisms in the enhancement of resistance to furunculosis, 2 groups of rainbow trout (Oncorhynchus mykiss) were immunized with supernatants of Aeromonas salmonicida or Escherichia coli cultures. The fish received 4 weekly intraperitoneal injections (70 micrograms of crude proteins). One control group was injected with phosphate-buffered saline, while another was untreated. Specific agglutinins were produced only in the fish immunized with A salmonicida supernatant. Polyspecific natural antibodies were measured using different antigens in an enzyme immunoassay. A significant rise (up to 3 times the mean titer of untreated controls) was observed in the 3 injected groups (even with PBS), which also displayed significant protection against experimental furunculosis (32 to 42% mortality versus 72% in controls). Thus, although the exact significance of natural antibodies still has to be confirmed, the importance of natural defenses and the difficulty in clearly inducing specific protection against furunculosis are confirmed.

Aeromonas↗
PubMed1990

[Exudative enteropathy and interstitial cystitis due to systemic lupus erythematosus].

A 33-year-old woman presented with chronic diarrhea, vomiting and anasarca due to systemic lupus erythematosus with protein-losing enteropathy, interstitial cystitis and glomerulonephritis. Methylprednisolone could not prevent aggravation of diarrhea, obstructive uropathy, and nephrotic syndrome, and prolonged intestinal ileus developed. Because of this steroid-resistance, bolus injections of cyclophosphamide (1 g i.v. monthly) were decided. Protein-losing enteropathy and ileus both disappeared rapidly following the first injection. Protein-losing enteropathy, intestinal ileus and interstitial cystitis are exceptional manifestations of systemic lupus erythematosus; steroid-resistance of the digestive manifestations has only been reported in one case and our observation is the first reporting the efficacy of cyclophosphamide.

Adult↗
PubMed1990

Brain glucose utilization under high sensory activation: hypoactivation of prefrontal cortex.

Brain glucose metabolism was studied, using positron emission tomography and [F-18]-2-deoxy-2-fluoro-D-glucose, in 13 healthy young adult men, at rest and under conditions of high visual and auditory stimulation with minor motor involvement. Despite high individual variations, the mean cerebral metabolic rate for glucose was highly increased during stimulation. Furthermore, the regional pattern of cerebral glucose utilization showed consistent differences between resting and activated states. Several brain areas, including temporal, motor-premotor and parieto-occipital cortices, and striatum, thalamus, and cerebellum showed a level of activation statistically comparable to that of mean gray. Significant preferential activation was found only in the visual cortex. By contrast, prefrontal and mesial cortical areas were relatively hypoactivated by the task. Inasmuch as prefrontal cortex is known to receive visual associative afferents, these observations are tentatively interpreted in terms of the "parallel" mode of information processing, along specific routes according to the environmental state.

Adult↗
PubMed1989

Assay and purification of the adenosylcobalamin-dependent 2-methyleneglutarate mutase from Clostridium barkeri.

A continuous spectrophotometric assay was developed for the adenosylcobalamin-dependent 2-methyleneglutarate mutase from Clostridium barkeri. Thereby the product (R)-3-methylitaconate is converted by the delta-isomerase from the same organism to 2,3-dimethylmaleate which absorbs at 240 nm, much higher than both parent compounds (delta epsilon = 3.7 mM-1.cm-1). In addition a discontinuous assay using the facile formation of 2,3-dimethylmaleic anhydride in aqueous solution at pH 0-1 (delta epsilon = 4.0 mM-1.cm-1 at 256 nm) was established. The mutase and the isomerase were purified together by chromatography on quaternary-amine-Sepharose (Q-Sepharose) and on cyanocobalamin-agarose. The enzymes were separated and obtained in homogenous forms by preparative PAGE in non-denaturing buffer. Both enzymes appear to be homotetramers with subunits of 70 kDa (mutase) and 50 kDa (isomerase). The equilibrium constants for both reactions were determined at I = 0.1 M and 25 degrees C: K1, app = [(R)-3-methylitaconate].[2-methyleneglutarate]-1 = 0.26 +/- 0.04, K2,app = [2,3-dimethylmaleate].[(R)-3-methylitaconate]-1 = 7.40 +/- 0.21.

Carbon-Carbon Double Bond Isomerases↗
PubMed1989

Radiation embryology.

Prenatal development, characterized by intensive cell proliferation, cell differentiation and cell migration, shows a high radiosensitivity. Therefore, radiation exposure of embryos and fetuses is of great concern for radiological protection and human health. Irradiation during gestation can cause death, growth disorders, malformations, functional impairment and malignant diseases in childhood. These effects are strongly dependent on the developmental stage at exposure and on the radiation dose. The first trimester of pregnancy is regarded as the period with the highest risk for malformation and cancer induction. The developing nervous system shows a special susceptibility to ionizing radiation over a long period and is therefore of great significance for risk estimation. Knowledge about radiation effects on prenatal development has been derived from animal experimentation and from the exposure of human embryos. There is evidence that doses between 1 and 10 cGy may lead to developmental anomalies and that the radiation response can be modified by additional factors.

Abnormalities, Radiation-Induced↗
PubMed1989

Positron tomography demonstrates frontal lobe hypometabolism in progressive supranuclear palsy.

A regional analysis of cerebral glucose metabolism was carried out in 9 patients with progressive supranuclear palsy by using positron emission tomography with fluorodeoxyglucose as the tracer. A consistent metabolic map of frontal hypometabolism was found in 7 patients. Brain metabolism was normal in 1 subject and diffusely decreased in another. In the 7 patients with selective hypofrontality, motor and premotor areas were severely hypometabolic, while heteromodal association cortex and paralimbic regions were comparatively less affected. Although this pattern of frontal alterations, probably due to disconnection, appeared consistent with the clinical features of the disease, it proved difficult to correlate the metabolic maps with neuropsychological disturbances.

Aged↗
PubMed1989

Decreased glucose utilization in the striatum and frontal lobe in probable striatonigral degeneration.

Nine positron emission tomography studies of regional cerebral glucose metabolism were performed in 7 patients with probable striatonigral degeneration, a disorder characterized by parkinsonian features and absent or poor response to L-dopa. When compared with values obtained in normal volunteers, mean cerebral glucose metabolism was slightly reduced in subjects with striatonigral degeneration who, in addition, had a marked (20.5%, +/- 3 SD) relative hypometabolism in putaminal and caudate nuclei. Significant hypometabolism was also found in motor/premotor as well as in prefrontal cortex. In 2 subjects who were studied twice a deterioration of relative striatal metabolism paralleled clinical evolution. Magnetic resonance imaging disclosed the presence of abnormal iron deposits in the putamen in all cases but showed no cortical anomalies. These results suggest that positron emission tomography with [18F]fluorodeoxyglucose may provide an index of cell and processes degeneration in the striatum in striatonigral degeneration and is able to detect functional deficits in frontal cortex. The presence of striatal hypometabolism might be a predictor of a poor response to L-dopa.

Aged↗
PubMed1989

Can smoking increase attention in rapid information processing during noise? Electrocortical, physiological and behavioral effects.

This study investigated the effects of smoking on subject-paced visual rapid information processing performance (RIP) under the influence of disturbing noise. The RIP task required the subjects to detect triads of even or odd digits within a pseudorandom sequence of single digits presented on a screen. Two groups of 12 female habitual smokers who were not allowed to smoke during the last 10 h preceding the test sessions underwent two test sessions each consisting of two RIP trials separated by a smoking period (habitual cigarette) for one group and by a relaxation period without smoking for the second group. Noise disturbance was presented during the second RIP trial of one of the two sessions only. Smoking increased RIP performance, but noise failed to show any measurable effect. EEG analyzed during RIP revealed the expected noise-induced decrease in alpha power. ERP analyses showed a smoking-induced decrease in the CNV-related negativity but no noise effects. The late positive wave (LP) increased after smoking, but to a lesser extent under the noise condition. The analyses of peripheral physiological measures revealed smoking- and noise-induced heart rate acceleration and cutaneous vasoconstriction. Plasma cortisol, prolactin and HGH were also increased after the noise session. The results indicate therefore that smoking increased RIP, whereas noise failed to affect mental performance, although it produced measurable vegetative stress effects.

Adult↗