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S Weis

Publications and source records attributed to S Weis.

At least 91 records · Page 5Linked to original sources
PubMed1994

Unusual ubiquitin-positive glial cells in the globus pallidus of normal elderly human brains.

Unusual glial cells, inconspicuous in routine histological sections, were demonstrated in the globus pallidus using immunohistochemistry for anti-ubiquitin and a modified NOR-silver impregnation technique. These cells were identified as astrocytes and showed the following unusual features: (i) presence of intracytoplasmic vacuoles; (ii) immunoreactivity for ubiquitin; (iii) positive staining with a modified NOR-silver impregnation technique; and (iv) topographical location restricted to the globus pallidus. Quantitative analyses showed the numerical density of these cells to be significantly increased with normal ageing, whereas the presence of the cells was not related to pathological ageing or any other disease process. The data suggest that, not only in neurons but also in glial cells, accumulations of altered proteins can be found, which is probably due to a decline in the proteolytic activity of the cell.

Adult↗
PubMed1993

Neuronal damage in the cerebral cortex of AIDS brains: a morphometric study.

Using stereological methods, two cerebral cortical areas from AIDS brains were investigated. Neuronal density, profile area of neurons, and perikaryon volume fraction were measured and compared to age-matched control brains. In the fronto-orbital cortex (area 11) of AIDS brains, a significant loss of neurons was seen. The perikaryon volume fraction was likewise decreased. The size of neurons did not differ between control and AIDS brains. In patients with clinical signs of progressive dementia and in brains with human immunodeficiency virus (HIV)-specific neuropathology (HIV-leukoencephalopathy and/or HIV-encephalitis) as compared to patients lacking these features, a small decrease in neuronal density was noted but this difference did not reach the level of statistical significance (P = 0.16). In the superior parietal lobule (area 7) of AIDS brains, no loss of nerve cells was noted. AIDS patients with progressive dementia and brains with HIV-specific neuropathology showed no difference in neuronal densities as compared to those without such features. We conclude that the fronto-orbital cortex, in contrast to the parietal cortex, is mainly damaged in AIDS brains. Neuronal loss was not significantly correlated with development of dementing symptoms and of HIV-specific neuropathology.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Astroglial changes in the cerebral cortex of AIDS brains: a morphometric and immunohistochemical investigation.

Astroglial changes in the cerebral cortex of AIDS brains were analysed by means of morphometry. Astrocytes with and without immunoreactivity for glial acidic protein (GFAP) were counted and their size was measured. In the two investigated cortical areas (frontal and parietal), a similar reaction pattern of astroglia was observed. The total number of astrocytes (i.e. GFAP-positive and GFAP-negative astrocytes) did not differ between control and AIDS brains. However, the number of GFAP-positive astrocytes was significantly increased in AIDS brains, while the number of GFAP-negative cells was significantly reduced. Nuclear size of GFAP-negative and GFAP-positive astrocytes was significantly increased. The reaction pattern of cortical astrocytes in AIDS seems to be characterized by GFAP production in protoplasmic astroglia as well as by hypertrophy of all astrocytes.

AIDS Dementia Complex↗
PubMed1992

The efficacy of gemfibrozil therapy for raising high density lipoprotein levels.

Thirty subjects, 5 normotriglyceridemic (NTG) with low HDL cholesterol (HDL-C < 35 mg/dl) and 25 hypertriglyceridemic (HTG) with low and high HDL-C (HDL-C > 35 mg/dl) were selected fo this study. They were treated with gemfibrozil (600 mg BID) for 12 weeks. In both groups, gemfibrozil significantly reduced serum TG levels (p < 0.005), yet HDL-C increased significantly only in HTG patients (p < 0.005). The changes in HDL-C levels were highly variable (-40 to 50%) and appeared to be dependent on the levels of serum TG achieved during treatment. Based on post-treatment serum TG, the HTG patients were divided into 2 groups. Group 1 with serum TG of < 100 mg/dL and Group 2 with serum TG levels > 100 mg/dl. Significant post treatment increases in HDL-C were seen only in Group 1 (p < 0.005). The two groups had similar pretreatment serum TG and HDL-C levels but the LDL-C was significantly higher in Group 1 (p < 0.025). Pretreatment serum LDL-C also correlated positively with the increases in HDL-C during treatment (r = 0.51, p < 0.01, n = 25). Consequently, the patients were divided into three groups based on their initial serum LDL-C levels (Group 1: LDL-C < 130 mg/dl. Group 2: LDL-C, 130-159 mg/dl and Group 3: LDL-C > 160 mg/dl). The HDL-C levels increased significantly upon treatment only in Group 3. Pretreatment levels of serum TG and HDL-C were not significantly different among the three groups. Initial body weight (r = -0.43 p < 0.025, n = 30) and percent change in body weight during treatment (r = -0.47, p < 0.025, n = 30) correlated negatively with the percent reduction in serum TG. The change in body weight also showed significant negative correlation with the changes in HDL cholesterol (r = -0.48, p < 0.25, n = 30). We conclude that gemfibrozil is most effective in reducing serum triglycerides, LDL-C and increasing serum HDL-cholesterol in HTG patients who also have comparatively high initial LDL cholesterol levels (Fredrickson's type IIb phenotype). For effective improvement of HDL-cholesterol in most HTG patients, serum TG levels need to be lowered below 100 mg/dl. Furthermore, the benefit of gemfibrozil therapy may be significantly enhanced by weight loss during treatment.

Adult↗
PubMed1991

Morphometry and magnetic resonance imaging of the human brain in normal controls and Down's syndrome.

A new powerful stereological tool for exact quantification of brain structures on magnetic resonance imaging (MRI) scans was used. Applying Cavalieri's principle, unbiased estimation of volume can be obtained. The method was applied to estimate the volume of different brain structures from normal controls. Data were used for comparison with data obtained by analyzing the brains of persons with Down's syndrome. A normalization procedure based on volume of cranial cavity is introduced and its advantages discussed, as is the coefficient of error as an indicator for the precision of the measurement.

Adult↗
PubMed1991

Morphometry of the corpus callosum in normal aging and Alzheimer's disease.

Changes of the human corpus callosum in normal aging and Alzheimer's disease were analysed by means of morphometry. A standardized computerized evaluation program was implemented allowing objective, quantitative and reproducible data. The various parts of the corpus callosum showed a different pattern of changes in normal aging as compared to Alzheimer's disease. In conclusion, in normal aging affects mostly the front-temporal interhemispheric fiber systems, whereas in Alzheimer's disease the parietotemporal commissural fibers are altered.

Aging↗
PubMed1990

Loss of neurons in the frontal cortex in AIDS brains.

Neurons of Area 11 in the fronto-orbital cortex of 18 unselected AIDS brains are analyzed by means of stereology. Neurological abnormalities including dementing symptoms were described in eight patients. Neuropathology diagnosed human immunodeficiency virus (HIV)-specific changes in four, and diffuse poliodystrophy in eight brains. The majority (71.4%) of these brains was immunoreactive for HIV antigens when tested by immunocytochemistry. A significant loss of neurons is found as compared to normal controls. Neuronal density in AIDS brains is reduced by 18%, and the perikaryon volume fractions is reduced by 31%. Although only speculation on pathogenesis of this neuronal loss is possible at present, it may represent a part of the pathomorphological substrate of AIDS-related dementia. Moreover, it confirms by quantitative means damage to the cerebral cortex in AIDS which has been described only qualitatively as diffuse poliodystrophy.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Collagen dysplasia in idiopathic carpal tunnel syndrome.

Surgical biopsies of dissected transverse carpal ligaments of patients with idiopathic carpal tunnel syndrome were examined with an electron microscope revealing collagen fibrils with extremely varying diameters. Morphometric analysis was performed on electron micrographs exhibiting fibrils with a small diameter comparable to that in control tissue as well as fibrils with a far larger diameter than could be observed in control tissue. Morphometric parameters were evaluated in order to analyse the relation between the number of and the area covered by collagen fibrils in the electron micrographs. In control tissue the numerical density per image area was twice the numerical density in carpal tunnel syndrome. However, the area fraction of the electron micrographs occupied by collagen fibrils in carpal tunnel syndrome and controls were equal.

Biopsy↗
PubMed1989

The cerebral dominances: quantitative morphology of the human cerebral cortex.

The aim of the present investigation was to detect differences between the left and right hemispheres at a macroscopical level using morphometric procedures. The volume fraction and the surface area of the different brain structures have been calculated from the profile area by stereological procedures. The volume, the relative volume fraction, the folded surface area as well as the mean cortical thickness were evaluated by stereology. Although some constant differences in the arrangement of sulci and their depth can be observed at a descriptive level, the quantitative morphological comparison between both hemispheres however only showed slight differences. The results are discussed with regard to the differences published up to the present. The morphometric methods will be discussed in detail.

Adult↗
PubMed1989

The controversy about a sexual dimorphism of the human corpus callosum.

A sexual dimorphism of the splenium corporis callosi in man was reported in 1982. The authors described the posterior part of the female corpus callosum to be larger and more bulbous than its male counterpart. From the lateralization research, it has previously been stated that the female brain is less well lateralized for visuospatial functions than the male. The authors postulated that a larger splenium implies a larger number of fibers and that the number of interhemispheric fibers correlates inversely with lateralization of function. However, their sample was very small and not adequately matched for sex. Therefore, we reinvestigated this question. A standardized computer assisted program will be presented. With this program the "classical" parameters have been evaluated and the "rotatory diameter measurement" was performed. No differences between the sexes were seen either for the splenium corporis callosi or for the other parts of the corpus callosum.

Adult↗
PubMed1988

Ultrastructural and autoradiographic investigations of cell cultures derived from tendons or ligamentous material from patients with fibromatous disorders.

Cell cultures were derived from tendons or ligamentous material from patients with carpal tunnel syndrome (CTS), Dupuytren's contracture (DP), tendopathia nodosa (TN) and hallux valgus (HV). The ultrastructure of the operation specimens as well as of the cell monolayers was investigated, using a floating sheet method in order to preserve both cell-to-cell contacts and the orientation of the monolayers. The histologic features of the tissues obtained in the operations were correlated with the ultrastructure of the cells in culture derived from these specimens. In DP, above all in the nodules, an activation of the capillary endothelium in the vicinity of myofibroblasts and mast cells was observed. In CTS the collagen fibrils varied extremely in diameter. In DP and TN biopsies a splicing process of helicoidly arranged fibrils could be seen. A disintegration of elastic fibers in the fibrillar and amorphous components was found in DP nodules, HV and TN tissues. Transitional forms between fibroblasts and myofibroblasts were observed not only in DP but also-though in a smaller percentage--in the cultures derived from the other patients. The cells showed organelles for active protein synthesis and transport. Autophagocytosis and the formation of multilamellated bodies took place in TN and HV cultures. In CTS, DP and TN cultures cells were connected via gap junctions. In some cultures, above all in those derived from CTS, monocilia were found. In CTS cultures the formation of intracellular collagen occurred. Growth parameters were rather low in HV cultures. PLmax (maximal pulse labelling index) values were higher in TN cultures than in DP and HV cultures. Plating efficiency (PE) values were higher in cultures derived from cell-rich and capillarized tissues than in biopsies with few cells.

Adult↗
PubMed1987

Morphometric analysis of collagen fibrils in idiopathic carpal tunnel syndrome.

Surgical biopsies of dissected transverse carpal ligaments of patients with idiopathic carpal tunnel syndrome were examined with an electron microscope revealing collagen fibrils with varying diameters. Morphometric analysis of transversely cut collagen fibrils was performed on photomicrographs exhibiting fibrils with a small diameter comparable to that in normal tissue as well as fibrils with a large diameter that could not be observed in normal tissue.

Carpal Tunnel Syndrome↗
PubMed1987

Morphometric analysis of collagen fibrils in idiopathic carpal tunnel syndrome: Part 2.

Morphometric parameters were evaluated in order to analyze the relation between number and covered area of collagen fibrils in normal and carpal tunnel syndrome tissue. This analysis revealed that in normal tissue twice as many collagen fibrils as in pathological tissue occupy an equal area. Taking these facts into account, some hypotheses are advanced.

Biopsy↗
PubMed1986

Angiotensin II control of the renal microcirculation: effect of blockade by saralasin.

The hydronephrotic rat kidney with intact circulation and innervation was split and spread out as a thin sheet in a tissue bath. The microvasculature was observed in vivo via television microscopy. We quantitated the effects of increasing concentrations (10(-9) to 10(-5) M) of saralasin (angiotensin II antagonist) applied locally in the tissue bath on microvascular diameters and on relative glomerular blood flow (measured using fluorescent labeled RBCs). Saralasin produced an increase in preglomerular diameters which was largest (37 +/- 11%) in the interlobular artery (there was no dilation in the afferent arteriole near the glomerulus), an increase in postglomerular diameters which was largest (17 +/- 4%) in the efferent arteriole near the glomerulus, and an increase in blood flow (19 +/- 4%). If these types of findings would hold for the normal kidney, it would suggest a role for angiotensin II in the control of total renal blood flow, in the regional distribution of flow, and in the control of filtration fraction. We also made control micropressure measurements using the servo-nulling approach. Pressures measured were: afferent arteriole, 65 +/- 5 mm Hg; intraglomerulus, 50 +/- 5 mm Hg; and efferent arteriole, 19 +/- 3 mm Hg. These data indicate that there is major vascular resistance near the glomerulus, especially in the efferent arteriole.

Angiotensin II↗
PubMed1986

Responses of in vivo renal microvessels to dopamine.

The split hydronephrotic kidney preparation was used to directly observe the effects of locally applied dopamine on the in vivo diameters of renal vessels. Dopamine (1 X 10(-6) to 3 X 10(-5) M) produced a concentration-dependent dilation of the arcuate and interlobular arteries and afferent arterioles. Efferent arterioles near the glomeruli also dilated to dopamine but the dilation was less than that of the preglomerular vessels. Higher dopamine concentrations (3 X 10(-4) and 1 X 10(-3) M) produced more variable effects, with a tendency for the arcuate and interlobular arteries and the afferent and efferent arterioles away from the glomeruli to decrease in diameter. After pretreatment with haloperidol, dopamine (1 X 10(-6) to 1 X 10(-4) M) did not dilate any pre- or postglomerular vascular segment, but the tendency for pre- and postglomerular constrictions with higher dopamine concentrations were not abolished. Pretreatment with phentolamine and propranolol enhanced the dilator response of the pre- and postglomerular vessels (except the afferent arterioles near glomeruli and efferent arterioles near welling points) to dopamine (3 X 10(-5) and 1 X 10(-4) M), and abolished the reductions in diameter produced by the high dopamine levels. These data indicate that the dilator effect of dopamine is mediated by interactions with specific dopaminergic receptors, while alpha and beta adrenergic receptors appear to mediate a constrictor influence observed with high dopamine concentrations. The overall effect of dopamine on the renal vessel diameters thus appears to depend on the balance of dilator and constrictor stimuli mediated by multiple receptors.

Animals↗