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Biomedical subjects

D Michel

Publications and source records attributed to D Michel.

At least 145 records · Page 8Linked to original sources
PubMed1991

[Organ protection and regression of hypertension by calcium antagonists].

Irrespective of the presence of hypertension, left ventricular hypertrophy, a cardiovascular risk factor in its own right, increases cardiac morbidity and mortality. In addition to ventricular hypertrophy, arteriole wall hypertrophy and its effects on endogenous vessel wall function are also important factors, in particular in hypertension. Calcium is involved in this process, the elevation of free intracellular calcium probably being of greater importance than calcium entering the cells via channels. Thus, effective drug-induced organ protection requires that the substance employed as an anti-hypertensive should lower blood pressure, reduce left-ventricular hypertrophy, and inhibit vascular changes. Animal experiments have shown that calcium antagonists meet these requirements.

Blood Pressure↗
PubMed1991

Pathology of roots, spinal cord and brainstem in syringomyelia-like syndrome of Tangier disease.

We report here a post-mortem examination of a 46-year-old patient who died after a 23-year-long syringomyelia-like syndrome of Tangier disease. The L5 dorsal root and the superficial peroneal nerve showed fiber loss and lipid vacuole accumulation in Schwann cell cytoplasm. The L5 ventral root had moderate fiber loss without lipid vacuoles. In the cervical roots, fiber loss was intense and there were no foamy Schwann cells. Motor neuron loss was severe in the cervical spinal cord and the facial nerve nucleus and slight at the lumbar level. Under electron microscopy, some neurons of the lower spinal cord showed atypical inclusions. These data suggest that an unknown metabolic defect is responsible for a primary neuronopathy. Lipid accumulation in Schwann cells, resulting from fiber degeneration is probably transient, accounting for the absence of foamy cells in regions with longstanding involvement.

Autopsy↗
PubMed1991

Unusual amyloid polyneuropathy with predominant lumbosacral nerve roots and plexus involvement.

We report a 25-year-old patient with a progressive asymmetric peripheral neuropathy of the distal lower limbs. Imaging studies showed enlargement of lumbosacral roots, plexus, and proximal sciatic nerve. Sacral plexus biopsy revealed amyloidosis associated with endoneurial edema. Immunohistochemistry with anti-prealbumin, serum amyloid A, and immunoglobulin light chain antisera failed to label the amyloid.

Adult↗
PubMed1991

[Different clinical types of degenerative aphasia].

The authors report 3 cases of slowly progressive aphasia with different language disturbances: anomia, pure word deafness and Broca's aphasia. All patients were independent in daily life activities. Insight, judgement and overall behaviour were intact. There was no major disturbance of other cognitive functions, but psychometric tests showed mild deficits suggesting widespread involvement. CT scans and magnetic resonance imaging showed focal dilatation of the left sylvian fissure. A positron emission tomographic study showed left perisylvian hypometabolism. A review of the literature yielded an increasing number of cases of this degenerative syndrome affecting dominant hemisphere language areas. Our cases confirm the clinical heterogeneity of degenerative aphasia. Postmortem neuropathological examinations are rare and many causes are found: Pick's disease, Alzheimer's disease or aspecific gliosis.

Aged↗
PubMed1990

[Medicamentous cardioprotection. 2: Hypertension].

Coronary heart diseases are three times more common in hypertensives older than 65 than in normotensive patients with comparable risk profiles. To be effective, cardioprotection must cover both elevated blood pressure and its consequences for the myocardium and coronary vessels (myocardial hypertrophy, microangiopathy and macroangiopathy), and should employ substances that have an effect on the underlying pathophysiological processes of hypertension and hypertensive cardiopathy. These preconditions are, at least in part, met by calcium antagonists, ACE-inhibitors and beta blockers. They have been proved to bring about a lasting decrease in blood pressure, and regression of cardiac enlargement. Regression of coronary sclerotic changes, however, is not yet certain. Overadditive effects have been described for the combination of calcium antagonists and ACE-inhibitors.

Antihypertensive Agents↗
PubMed1990

[Cardioprotection with drugs. 1: Coronary heart disease].

Drug-induced cardioprotection, that is, protection of the heart from injuries of all kinds, is of particular importance in coronary heart disease, especially in fresh myocardial infarction including unstable angina pectoris, within the framework of secondary prevention after infarction, and in chronic coronary insufficiency (stable angina pectoris, silent ischemia). In the case of fresh infarctions, functional myocardium can be protected or salvaged in particular by early thrombolysis, early administration of calcium antagonists or beta blockers (in particular the combination of calcium antagonists with beta blockers). In the area of secondary prevention, beta blockers predominate. In chronic coronary insufficiency, calcium antagonists, nitrates and beta blockers are the first-choice cardioprotective agents.

Adrenergic beta-Antagonists↗
PubMed1990

Fibrin seal in wound healing: effect of thrombin and [Ca2+] on human skin fibroblast growth and collagen production.

To assess the interaction of a fibrin sealant with wound healing, an in vitro study using human skin fibroblasts was carried out. The effect of thrombin and calcium concentrations in the sealant on the growth parameters and collagen synthesis by normal human skin fibroblasts was examined. The fibroblast proliferation was increased 3 times for 50 and 25 IU of thrombin/ml. However for 20 mM [Ca2+], this stimulating effect of thrombin was observed after an 8 day incubation period, whereas it was observed as soon as the 2nd day in the presence of 2 mM [Ca2+]. The high rate of [Ca2+] (20 mM) partly inhibited DNA synthesis: for 2 mM [Ca2+], the incorporation of [3H]-Thymidine was 4 times greater than for 20 mM [Ca2+]. Further experiments demonstrated that human skin fibroblasts in the presence of 50 IU of thrombin/ml and 2 mM [Ca2+] in fibrin seal could increase the type I and III collagen synthesis while increasing the ratio of type III to type I. Thus, our results suggest that in vivo wound healing which required fibroblast growth and collagen synthesis can be stimulated in the presence of fibrin glue which is in good accordance with previous clinical observations.

Calcium↗
PubMed1990

Mortality trends among refugees in Honduras, 1984-1987.

Mortality data collected from 1984 to 1987 through a routine standardized health information system in the five main refugee populations of Honduras were reviewed. The direct standardized mean annual death rate for all refugees was 5.5 per 1000 population (Honduras population as reference; Honduras mortality rate: 10.1 per 1000). Mortality decreased or remained stable among Salvadoran refugees from 1984 to 1987, but increased among Nicaraguan refugees after 1985. The highest neonatal (56.1 per 1000 livebirths), infant (126.1 per 1000 livebirths) and under-five-year-olds (35.7 per 1000 child less than five years of age) mortality rates were observed in the two Nicaraguan camps. These two camps had the highest rate of newly arriving refugees. Deaths in infants and under-five-year-olds accounted for 42 and 54.1% of all deaths respectively. Of all deaths under five years of age, respiratory infections, diarrhoeal diseases and measles accounted for 21.4%, 22.1% and 4.7%, respectively. Mortality rates, particularly among under-five-year-olds and infants increased when the rate of newly arriving refugees was higher. The importance of adapted health surveillance in refugee settlements is discussed.

Adolescent↗
PubMed1990

Down regulation by p60v-src of genes specifically expressed and developmentally regulated in postmitotic quail neuroretina cells.

The avian neuroretina (NR) is composed of photoreceptors and different neurons that are derived from proliferating precursor cells. Neuronal differentiation takes place after terminal mitosis. We have previously shown that differentiating NR cells can be induced to proliferate by infection with Rous sarcoma virus (RSV) and that cell multiplication requires expression of a functional v-src gene. We speculated that the quiescence of NR cells could be determined by specific genes. Cell proliferation could then result from the negative regulation of these genes by the v-src protein. By differential hybridization of a cDNA library, we isolated eight clones corresponding to genes expressed in postmitotic NR cells from 13-day-old quail embryos, transcriptional levels of which are significantly reduced in NR cells induced to proliferate by tsNY68, an RSV mutant with temperature-sensitive mitogenic activity. Partial sequencing analysis indicated that one RNA encoded the calmodulin gene, whereas the other seven showed no similarity to known sequences. By using v-src mutants that induce NR cell proliferation in the absence of transformation, we showed that transcription of six genes was negatively regulated by the v-src protein and that of four genes was correlated with NR cell quiescence. We also report that a subset of genes are specifically transcribed in neural cells and developmentally regulated in the NR. These results indicate that the v-src protein regulates expression of genes likely to play a role in the control of neural cell growth or differentiation.

Animals↗
PubMed1990

Pure agraphia after deep left hemisphere haematoma.

Pure agraphia is reported following haematoma in the left centrum semiovale sparing both parietal and frontal cortices. There was total inability to produce graphemes in the absence of limb apraxia. The lesion is assumed to have prevented linguistic and graphemic systems from gaining access to the frontal motor programme.

Adult↗
PubMed1990

[Primarily unilateral herpes encephalitis. Long-term neuropsychological study of 9 cases].

Nine cases of post-herpetic encephalitis with predominant involvement of one temporal lobe at CT scan or MRI (6 on the left and 3 on the right sides) were studied 1 to 6 years after onset with repeated language and memory testing. The neuropsychological findings were well correlated with the lateralization and size of the lesions, as previously observed in unilateral temporal lobectomy. Compared with the usual bilateral form, the sequelae were mild, and all the patients, especially those with right hemisphere involvement, resumed a subnormal family life or social activity. In patients with left predominant lesions the anterograde amnesia concerned verbal information, especially logical and abstract, without visual amnesia. In some cases, the episodic verbal amnesia was associated with a semantic deficit which included the knowledge of some words. In one patient the colour, use and mental imagery of some objects corresponding to forgotten words were involved only for some specific groups (natural objects, whereas man-made objects fared better). Testing of verbal memory is proposed to determine the role of the preserved minor hemisphere in learning the context of word presentation, and words with concrete and visual connections which are better recalled than those with abstract or logical link. Disorders of behaviour or mood are usual in the 2 groups of lesions. Thus, herpes encephalitis in these asymmetrical and benign forms in an attractive model to study the role played by the temporal lobe and lateralization in memory.

Adult↗