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Biomedical subjects

V Meininger

Publications and source records attributed to V Meininger.

At least 91 records · Page 5Linked to original sources
PubMed1984

A quantitative Golgi analysis of the postnatal maturation of dendrites in the central nucleus of the inferior colliculus of the rat.

In this work, we used Golgi impregnation and computer assistance to analyze the quantitative development of the dendrites of neurons in the central nucleus of the inferior colliculus in the rat from 8 (P8) to 20 (P20) days of age, i.e., during the period of functional maturation of the auditory system. The number and length of the dendritic segments and the number of spines of a total of 516 impregnated cells were studied. The variations of both the mean number of peripheral dendritic segments and the mean dendritic domain area suggest that the dendritic tree of these cells is orientated preferentially in the sagittal plane before the onset of functional maturation, but undergoes a reorientation in the frontal plane during this critical period. The length of dendritic segments varies as a function of both the stage of the period of functional maturation and the order of magnitude of these segments. During the first stage, from P8 to P16, only proximal and intermediate segments lengthen, the distal segments increasing their length later from P16 to P20. The lengthening of the dendritic segments is associated with dramatic reabsorption of the dendritic spines on all dendritic segments and seems closely related to the functional maturation of the auditory pathways.

Animals↗
PubMed1984

[Methylation of erythrocyte membrane phospholipids: correlation with membrane viscosity. Study of normal and parkinsonian subjects].

Plasma membranes from erythrocytes were used to study various parameters: phospholipid methylation, viscosity and fragility. These parameters were analysed in 57 normal subjects (52 +/- 3 years old) and 14 patients with idiopathic Parkinson's disease without previous treatment (71 +/- 2 years old). No significant correlations were observed between the various parameters and sex or age in the normal group. No correlation was observed between fragility and methylation or viscosity. A statistically significant correlation was found between viscosity and phospholipid methylation. In the patients with Parkinson's disease, fragility is identical to the normal group but the viscosity is increased by 25 p. 100. The increase of viscosity is more obvious among the patients with a pure or predominantly akinetic form of the disease. These results favour the previously described correlation between phospholipid methylation and viscosity of the plasma membrane and suggest a modification of these parameters in Parkinson's disease. They also suggest that the increased viscosity observed in Parkinson patients could render the receptors inaccessible to their endogenous ligands.

Adolescent↗
PubMed1983

The loss of motorneurons corresponding to specific muscles in the wobbler mutant mouse.

The spinal motorneuronal pools specific to a peripheral muscular territory were studied in the wobbler mutant mouse, with the use of retrograde transport of horseradish peroxidase, which was injected into the musculo-cutaneous nerve and into the distal part of the sciatic nerve. Counts of labeled cells showed that the mean percentage of surviving motorneurons was 48.4% in the case of the musculo-cutaneous nerve and 83.6% in the case of the sciatic nerve. The cell loss was not found to be different in old compared to young mutants, suggesting that motorneuron degeneration is an early event in the course of the disease.

Animals↗
PubMed1983

Postnatal development and cell death in the sciatic motor nucleus of the mouse.

Motoneurons of the sciatic nerve were studied in the lumbar cord of the mouse, at various postnatal stages, 1-3 days, 6-7 days, three weeks, and 2-3 months. Horseradish peroxidase (HRP) was applied at the cut end of the distal sciatic nerve, and, after retrograde transport, transversal and longitudinal histological sections of the cord were made in order to compare various features of the motor pool such as cell grouping, position in gray matter, cell number, cell size, and gross dendritic patterns. As early as birth, sciatic nerve motoneurons were grouped in a longitudinal column in the homolateral gray matter. No labelled cells were found outside the column either ipsilaterally or contralaterally. The location of the column was constant throughout postnatal development, encompassing the same spinal root levels and occupying the same position in the gray matter, the lateral portion of the ventral horn. Cell volume showed a 4-5 fold increase. Dendrites were not visible at the early stages and became labelled at 2-3 months. The neuropil also displayed a 4-5 fold increase, causing considerable spacing of the motoneurons. Histograms of cell body volume showed the progressive differentiation of the initially uniform motoneuronal pool in different sub-populations. In each experimental animal, labelled cells were counted in all histological sections and, for statistical comparison, the value was corrected for mean cell size. A 31% decrease in the number of labelled cells was observed between birth and 2-3 months. The rate of cell death was not constant, since 17% disappeared during the first week and 14% thereafter. The 31% decrease was lower than that observed in previous studies in the rat, 50-80%. The difference in species may explain this discrepancy, however, technical differences must also be invoked. In these studies, HRP was injected into the biceps brachii muscle. An overestimation of cell death is possible with this technique because postnatal changes of the axonal endings permit easier HRP uptake in immature muscles than in mature muscles. The cut nerve technique however by-passes the axonal endings.

Aging↗
PubMed1983

Ultrastructural localization of tubulin and actin in polyethylene glycol-embedded rat seminiferous epithelium by immunogold staining.

The polyethylene glycol (PEG) method for immunofluorescence localization of cytoskeletal antigens has been extended to the ultrastructural level using glutaraldehyde-fixed tissues and immunogold staining. Semithin sections of fixed tissue embedded in polyethylene glycol are divested of the PEG, exposed to purified antibodies (e.g., antiactin, antitubulin) and anti-IgG-colloidal gold. The sections may be processed by dehydration and critical-point drying, or reembedment in hydrophilic substances. Tubulin is demonstrated in the mitotic spindles of dividing spermatogonia, manchettes, axonemes and centrioles of developing spermatids, and in the Sertoli cell cytoplasm; actin localization is demonstrated in the myoid cells of the tunica propria, and smooth muscle cells of arterioles in the interstitial tissue. The results demonstrate the applicability and versatility of PEG embedding for immunocytochemistry.

Actins↗
PubMed1983

[Crossed cerebellar atrophy following hemispheric lesions occurring in adulthood].

Crossed cerebellar atrophy generally results from a large contralateral hemispheric lesion involving the cortico-spinal tract in neonates or infants. Two cases of crossed cerebellar atrophy which were particular from two points of view are reported: 1) the cerebellar alterations resulted from cerebral lesions which had occurred in adult life, after complete maturation of the central nervous system. One was observed in a 78 years old hypertensive woman who had presented 24 years before a right lenticular haemorrage, the other in a 73 years old woman who when aged 18 had presented a left cortical frontal traumatic lesion. The clinical and pathological data are compared to 13 similar cases reported in the literature. The retrograde or anterograde route of this transneuronal degeneration is discussed. The pathological features of those 2 cases lead the authors to favor the anterograde route; 2) the cerebral lesion was small and strictly limited to F2 in 1 case, the secondary lesions involving then, only the medial pontine nuclei and the quadrangular cerebellar lobule. This allows a clear demonstration, in man, of a systematisation of the cortico-pontine and ponto-cerebellar fibers similar to what has been described in the animal (Brodal, 1980).

Age Factors↗
PubMed1982

[L-Methionine treatment of Parkinson's disease: preliminary results].

Eleven patients with previously untreated Parkinson's disease were treated with L-Methionine for periods from 2 weeks to 6 months. The treatment was well supported and good improvement in clinical signs, particularly akinesia and rigidity, appeared within approximately three weeks, the effect on tremor being less marked. Therapeutic effects were similar to those observed with L-dopa treatment. Correlation of clinical effects with a marked increase in the number of 3H-Spiroperidol binding sites (Bmax) to lymphocytes was noted. This therapeutic effect suggests the role played by modifications of membrane fluidity on dopaminergic receptors, both lymphocytic and striatal, in the etiology of Parkinson's disease, and opens up new therapeutic possibilities in this disease.

Aged↗
PubMed1981

Postnatal modifications of the dendritic tree of cells in the inferior colliculus of the cat. A quantitative Golgi analysis.

Postnatal modifications of dendrites have been quantitatively studied by network analysis of the dendritic tree in the two central nuclei of the inferior colliculus in the cat. This analysis revealed cells with two types of branching patterns suggesting two different modes of growth. The predominant pattern is characterized by dichotomous branching on random segments (DR cells). However, a purely collateral branching pattern is particular to certain cells (CB cells). These two branching patterns were found in both nuclei of the IC in adult and young cats, but the exact significance of these two cell types remains unclear. The dendritic trees of cells in kittens differed from those of the adult cat. Also, the types of modification were different in the two functionally distinct nuclei of the inferior colliculus that we studied. The most dramatic modifications were observed in the dendritic tree of DR cells in the central nucleus, which receives fibers from the auditory nuclei in the brainstem. Two parameters were modified: the mean number of terminal segments and the mean total length of segments. Both parameters increased in the sagittal plane and decreased in the frontal plane. These modifications indicate a reorientation of the dendritic tree in the sagittal plane, along the incoming axons from the auditory nuclei. As these afferents become functionally mature only after birth, this spatial remodeling of the dendrites seems closely related to functional maturation of secondary auditory axons. In the dorsomedial nucleus that receives fibers from the auditory cortices, the dendritic tree of DR cells also undergoes spatial reorientation. This is more evident in the horizontal plane and with respect to the incoming axons. Our results suggest that the characteristic orientation of the dendritic tree of cells observed in the inferior colliculus of the adult cat is established only after the first postnatal weeks. This orientation seems to result from an active process of remodeling concomitant with the functional maturation of afferents, a fact already established for various cell types in the nervous system.

Afferent Pathways↗
PubMed1981

[Dopaminergic receptors on lymphocytes in idiopathic Parkinson's disease (author's transl)].

(3H) spiroperidol binding has been measured in lymphocytes from patients with Parkinson's disease and age matched healthy volunteers. A dramatic decrease (73 p. 100) in the number of binding sites Bmax without any variation of the affinity KD has been observed in untreated Parkinsonian patients. This decrease in Bmax is linearly correlated with the degree of disability of the Parkinsonian patients (r = 0.891, p less than 0.001). This decrease appeared to be relatively selective since no variation was observed with patients suffering of other neurological disorders. The possible relationships with the number of striatal dopamine receptors are discussed. With levodopa therapy, Bmax had the same mean value as in control subjects. This result means that levodopa induces an increase in lymphocyte binding sites and in five patients this increase could be observed by study before and during drug administration. In some severely disabled patients who had received levodopa for several years, Bmax was found much lower or higher than the mean value, which may suggest different interpretations of drug unefficiency.

Adult↗
PubMed1981

[Organization of pectoral muscle motor neurons in the rat. Contribution to the study of the axillary arch (Achselbogen)].

In spite of their role of the forelimb activity, the organization of the mammalian pectoral muscles remains unclear. In order to get more information, we have studied, qualitatively and quantitatively, the motor pools of the various pectoral muscles in the rat (musculus pectoralis major, musculus pectoralis minor and musculus panniculus carnosus). The method applied was the retrograde transport of horseradish peroxidase by the peripheral nerves supplying the various muscles. The results provided the precise localization within the ventral horn of the motor neurons from the pectoral muscles which were all in the most ventral part of the gray matter. Three distinct motor pools were observed, which confirms the functional identity of each muscle. The motor neurons of m. panniculus carnosus exhibited some particularities. They were 4 times more numerous than those from m. pectoralis major, they occupied the whole ventral edge of the ventral horn, from its medial part to its lateral tip. The cell size was different from that of the other muscles. These results were discussed, according to the role of this muscle, which links the forelimb to the whole trunk. In mammals, m. panniculus carnosus constitutes, with musculus latissimus dorsi, the axillary arch (Achselbogen). A small area of overlapping between the motor pools of these two muscles was observed. It was suggested that the muscular fibers from the axillary arch were innervated by the same, well-defined spinal area, independent of the muscle from which they originate.

Animals↗
PubMed1980

[Neuropathological study of adult intracranial hemorrhage. III. Analysis of 107 meningeal hemorrhages due to rupture of arterial aneurysms].

The findings in 107 pathological studies of meningeal hemorrhages due to rupture of arterial saccular aneurysms are reported. There were 62 women (58 p. 100) and 45 men (42 p. 100). Mean age was 56, lower in men (53) than in women (58). 45 aneurysms of the Anterior Communicating Artery, 26 of the Middle Cerebral Artery, 15 of the Internal Carotid Artery, 10 of the Anterior Cerebral Artery, 1 of the Anterior Choroidal Artery and 10 of the Posterior System were studied. These ruptured aneurysms were compared to 31 non ruptured ones. Mean size of the ruptured aneurysms was 10, 62 mm, not statistically different from that of non ruptured aneurysms (9, 05 mm). Multiple aneurysms represent 10 p. 100 of the whole ruptured aneurysms population. They affected mostly the Middle Cerebral Artery. High blood pressure had been present in 56/107 cases of ruptured aneurysms (52 p. 100). The prevalence of high blood pressure in patients with ruptured aneurysms (men: 60 p. 100 between 35 and 49, 63 p. 100 between 50 and 64; women: 31 p. 100 between 35 and 49, 54 p. 100 between 50 and 64) was statistically higher than in the same age and sex ranges of the general French population. The other causes of bleeding were rare: 4 liver cirrhosis (2 of the patients were also hypertensive) and 5 anticoagulant therapies (2 of which were also associated with high blood pressure). Intracerebral hematomas were found in 43 cases (40 p. 100): 39 lobar, more frequent in the frontal (26) than in the temporal (13) lobes, due mainly to Anterior Communicating Artery and Anterior Cerebral Artery aneurysms; very few were in the basal ganglia (3) or brainstem (I). Intraventricular hemorrhage was found in 39 cases (36 p. 100). Forty (37 p. 100) cerebral infarcts had occurred. They were located in the territory of the same artery in 20 cases (19 p. 100), in a different territory in 11 cases (10 p. 100), in both in 9 cases (8. p. 100).

Adult↗