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Biomedical subjects

S Weis

Publications and source records attributed to S Weis.

At least 37 records · Page 2Linked to original sources

Primary meningeal sarcomas in two children.

Primary meningeal sarcomas are rare but highly aggressive tumors predominantly affecting children. The clinical course, imaging characteristics and histopathological features of meningeal sarcomas in two pediatric patients are presented. Furthermore, we critically discuss the new WHO classification of these entities comparing them to older descriptions. In a 6-year-old girl, a cranial computed tomography (CT) scan was performed, after a mild head trauma, showing a parieto-occipital hemorrhage. One month later, a circumscribed mass adhering to the meninges and with central areas of hemorrhage was evident on magnetic resonance imaging (MRI) scans. Brain biopsy revealed a polymorphocellular sarcoma originating from the leptomeninges and infiltrating the brain. In an 8-year-old girl, who presented with headaches and vomiting, several MRI-examinations were inconspicuous for nearly one year until the latest MR-scan revealed a diffuse contrast enhancement of the leptomeninges of the whole brain and spinal canal. After open biopsy, primary leptomeningeal sarcomatosis was diagnosed. Although CT and MRI did not allow a specific diagnosis in both cases the exact visualization of the extent of the tumor and/or meningeal involvement was possible. Since there are no specific imaging criteria to differentiate meningeal sarcoma from other solid brain tumors or from other tumoral or inflammatory meningioses brain biopsy is indispensable. In order to avoid misinterpretations and delays of therapy, early open brain biopsy or surgical resection of the lesion is necessary in cases of unclear brain masses, especially of unclear meningeal processes. Due to the low number of cases published so far, the biological behavior and clinical management of this tumor entity still awaits further investigation.

Child↗

Gliomatosis cerebri: post-mortem molecular and immunohistochemical analyses in a case treated with thalidomide.

Gliomatosis cerebri (GC) is a rare tumor of the central nervous system (CNS) characterized by widespread diffuse infiltration of the brain and spinal cord by neoplastic glial cells. We report the case of a 17-year-old boy with a bioptically diagnosed fibrillary astrocytoma. The administration of thalidomide, which was suggested to be beneficial in the treatment of human cancers, had no substantial clinical effect on our patient. Autopsy studies revealed a diffuse infiltration of the frontal and temporal lobes of the right hemisphere, brainstem, and the leptomeninges covering the whole spinal cord by an astrocytic tumor, which showed features both of low-grade astrocytoma and glioblastoma multiforme. No mutations in the p53 and PTEN tumor suppressor genes were found; immunoreactivities for p53, PTEN, and EGFR could not be detected.

Adolescent↗

Etomidate and thiopental inhibit platelet function in patients undergoing infrainguinal vascular surgery.

BACKGROUND: Postoperative platelet hyperaggregability following general anesthesia has been reported in patients undergoing major vascular surgery. In contrast, since anesthetic agents inhibited platelet function both in vitro and in vivo, an increased risk for postoperative bleedings due to prolonged platelet dysfunction has been discussed. Nevertheless, data describing platelet-affecting properties of induction agents such as etomidate and thiopental in patients undergoing major vascular surgery are lacking. METHODS: Platelet function was determined at 0, 2, 20, and 200 microg/ml thiopental and at 0, 0.2, 2, 20 microg/ml etomidate in vitro in blood samples drawn from 16 patients suffering from severe occlusive arterial disease. In addition, 30 patients undergoing vascular surgery were investigated before (PRE) and after anesthesia induction (T0) either with etomidate (ETO group, n=16) or thiopental (THIO group, n=14), and 2 h after the beginning of surgery (T2). Platelet function was determined according to platelet aggregation, in vitro bleeding time, and flow cytometric measurements. RESULTS: In vitro, P-selectin expression was inhibited by etomidate at 2 and 20 microg/ml (-28% and -38%, respectively) and also by thiopental at 200 microg/ml (-27%). In patients undergoing vascular surgery, anesthesia induction in the ETO group resulted in a 31% prolongation of the in vitro bleeding time and an inhibition of ADP- and collagen-induced platelet aggregation (-30% and -17%, respectively) and of P-selectin expression (-25%) at T0. In the THIO group, only ADP-induced platelet aggregation was affected (-16%). At T2, all parameters had reached PRE level again in both groups. Furthermore, in comparison with the THIO group, operation time was significantly prolonged and transfusion volume was significantly increased in the ETO group. In addition, platelet count and hematocrit significantly decreased at T2, whereas levels of tPA, PAI-1, fibrinogen and antithrombin III and partial thromboplastin time remained unchanged in both groups during the study period. CONCLUSIONS: In the present study, etomidate and, to a minor extent, thiopental offered significant platelet inhibitory properties. Anesthetic-induced platelet inhibition may lead to higher transfusion rates and prolonged operation times. Therefore, anesthetic-related platelet inhibitory properties should be considered when searching for the anesthetic agent of choice, especially in patients with compromised hemostasis and co-existing bleeding disorders.

Aged↗

Sonography and neuropathology of a congenital brain tumor: report of a rare incident.

A rare case of a congenital brain tumor was diagnosed by sonography in a fetus at 33 weeks' gestation. The ultrasound examination showed a large area of both increased echogenicity and echolucency in one hemisphere suggestive of brain tumor or hemorrhage. The neuropathological examination revealed an undifferentiated glial tumor with large areas of necrosis.

Adult↗

Air Force/Texas Coronary Atherosclerosis Prevention Study (AFCAPS/TexCAPS): efficacy and tolerability of long-term treatment with lovastatin in women.

The Air Force/Texas Coronary Atherosclerosis Prevention Study (AFCAPS/TexCAPS) is the first coronary heart disease (CHD) primary prevention trial of the cholesterol-reducing agents called "statins" to include women. For 5608 men and 997 postmenopausal women without clinical evidence of cardiovascular disease (CVD) who had average low-density lipoprotein cholesterol (LDL-C) and below average high-density lipoprotein cholesterol (HDL-C), 20-40 mg/day lovastatin reduced first acute major coronary events (AMCEs) 37% (for those receiving placebo and lovastatin, respectively, 183 and 116 first AMCEs defined as fatal or nonfatal myocardial infarction [MI], unstable angina, or sudden cardiac death; relative risk [RR] 0.63; 95% confidence interval [95% CI] 0.50, 0.79; p < 0.001). Statistically significant reductions in prespecified secondary end points (coronary revascularizations, unstable angina, MI, cardiovascular end point events, and coronary end point events) were also associated with lovastatin treatment in the overall cohort. This paper provides results in women, a prespecified subgroup. Among women, 20-40 mg/day lovastatin reduced LDL-C 25% and increased HDLC 9% (p < 0.001). A prespecified analysis revealed consistency with the overall results regardless of gender (i.e., there were no statistical differences between men and women in risk reduction for first AMCEs with lovastatin). However, the number of women who had an AMCE was small, and there was insufficient power to detect a treatment group difference among women (7 of 499 vs. 13 of 498 first AMCEs in those receiving lovastatin and placebo, respectively; RR 0.54; 95% CI 0.22, 1.35; p = 0.183). Numerical reductions in all prespecified secondary end points were observed for women treated with lovastatin, but again, the numbers of events were small and the differences were not statistically significant. Chronic long-term treatment with lovastatin was well tolerated, with no treatment group differences in the frequency of cancer, muscle symptoms, and clinically important liver enzyme elevations. In AFCAPS/TexCAPS, a consistent pattern of numerical reductions in all prespecified primary and secondary cardiovascular end points was observed in women treated with lovastatin for primary prevention of CHD. However, because of the small number of events, there was insufficient power to detect significant treatment group differences. Lovastatin treatment was associated with statistically significant decreases in LDL-C and increases in HDL-C, and chronic long-term treatment with 20-40 mg/day lovastatin was well tolerated in women.

Aged↗

Defective mitochondrial oxidative phosphorylation in myopathies with tubular aggregates originating from sarcoplasmic reticulum.

Abnormalities of the sarcotubular system presenting as tubular aggregates (TAs) have been described in a variety of neuromuscular disorders. Here, we report on immunohistochemical and biochemical findings in 7 patients (2 familial and 5 sporadic cases) suffering from myopathies with TAs. In muscle biopsy specimens from 5 of the 7 patients, TAs were immunopositive for the ryanodine receptor (RYR 1) of the sarcoplasmic reticulum (SR), the SR Ca2+ pump (SERCA2-ATPase), and the intraluminal SR Ca2+ binding protein calsequestrin, indicating an SR origin of these aggregates. Furthermore, these 5 cases showed decreased respiratory chain enzyme activities (NADH:CoQ oxidoreductase. complex I and cytochrome c oxidase [COX], complex IV), while the remaining 2 patients exhibited normal values. Our findings indicate a functional link between mitochondrial dysfunction and the presence of TAs originating from the sarcoplasmic reticulum.

Adult↗

Heterogeneous tissue distribution of a mitochondrial DNA polymorphism in heteroplasmic subjects without mitochondrial disorders.

CONTEXT: Several maternally inherited point mutations of the mitochondrial genome cause mitochondrial disorders, but the correlation between genotype and phenotype remains obscure in many cases. The same mutation may cause various diseases, probably because of a different tissue distribution. OBJECTIVE: To assess the role of random somatic segregation in generating interperson differences by analysis of an apparently neutral polymorphism. DESIGN: Screening of 81 brain samples from subjects without mitochondrial disorders and selection of five necropsy cases showing a high level of heteroplasmy for the polymorphism. MAIN OUTCOME MEASURES: A proportion of various distinct genotypes in the mtDNA pool of the tissues, identified by fluorescent PCR products, representing a short polycytosine tract of variable length in the mitochondrial displacement loop. RESULTS: Differences were found between organs or groups of organs within subjects, pointing towards somatic segregation of mtDNA. In addition, marked differences of this organ distribution occurred between subjects, which cannot be explained by tissue specific selection. CONCLUSIONS: The observed interperson differences can be explained by somatic segregation, which occurs randomly at various developmental stages. Besides tissue specific selection, this process might participate in the distribution of pathogenic mtDNA mutations.

Adolescent↗

Effect of lovastatin on cardiovascular resource utilization and costs in the Air Force/Texas Coronary Atherosclerosis Prevention Study (AFCAPS/TexCAPS). AFCAPS/TexCAPS Research Group.

This cost-consequences analysis of the Air Force/Texas Coronary Atherosclerosis Prevention Study compares the costs of lovastatin treatment with the costs of cardiovascular hospitalizations and procedures. The cost of lovastatin treatment was defined as the average retail price and the cost of drug safety monitoring and adverse experiences. Costs were determined by actual rates of hospitalizations and procedures. Within a trial, lovastatin treatment cost approximately $4,654/patient. Lovastatin treatment significantly reduced the cumulative rate of cardiovascular hospitalizations and procedures (p = 0.002). Over the duration of the study, the cumulative number of cardiovascular hospitalizations and related therapeutic procedures was significantly reduced by 29%. The time to first cardiovascular-related hospitalization or procedure was significantly extended by lovastatin (p = 0.002). Lovastatin reduced the frequency of cardiovascular hospitalization (28%), and cardiovascular therapeutic (32%) and diagnostic procedures (23%). Among therapeutic procedures, treatment reduced coronary artery bypass graft surgery by 19% and percutaneous transluminal coronary angioplasty by 37%. Total cardiovascular-related hospital days were reduced by 26% (p = 0.025). The between-group offset in direct medical costs was $524, which resulted in a 11% cost offset of lovastatin therapy over the mean study duration of 5.2 years. Lovastatin provides meaningful reductions in cardiovascular-related resource utilization and reductions in direct cardiovascular-related costs associated with the onset of coronary disease.

Aged↗

The neuropathology of heroin abuse.

A broad spectrum of neuropathologic changes are encountered in the brains of heroin abusers. The main findings are due to infections, either due to bacterial spread from bacterial endocarditis, mycoses, or from HIV-1 infection. Other complications include hypoxic-ischemic changes with cerebral edema, ischemic neuronal damage and neuronal loss, which are assumed to occur under conditions of prolonged heroin-induced respiratory depression, stroke due to, for example, thromboembolism, vasculitis, septic emboli, hypotension, and positional vascular compression. Myelopathy is believed to be the result of an isolated vascular accident within the spinal cord due to an as yet unknown mechanism. A distinct entity, spongiform leukoencephalopathy, has been described mainly after inhalation of pre-heated heroin. A lipophilic toxin-induced process was considered to be due to contaminants and to be induced or enhanced by cerebral hypoxia, but a definite toxin could not be identified. At the cellular level, abnormalities in signal transduction systems and changes of various receptor densities have been reported. The exact etiology of the different neuropathological alterations associated with heroin abuse is still unclear, but may also be related to additional substances used as adulterants.

Autopsy↗

Relation between baseline and on-treatment lipid parameters and first acute major coronary events in the Air Force/Texas Coronary Atherosclerosis Prevention Study (AFCAPS/TexCAPS).

BACKGROUND: The Air Force/Texas Coronary Atherosclerosis Prevention Study (AFCAPS/TexCAPS) is the first primary-prevention study in a cohort with average total cholesterol (TC) and LDL cholesterol (LDL-C) and below-average HDL cholesterol (HDL-C). Treatment with lovastatin (20 to 40 mg/d) resulted in a 25% reduction in LDL-C and a 6% increase in HDL-C, as well as a 37% reduction in risk for first acute major coronary event (AMCE), defined as fatal or nonfatal myocardial infarction, unstable angina, or sudden cardiac death. This article describes the relation between baseline and on-treatment lipid and apolipoprotein (apo) parameters and subsequent risk for AMCEs. METHODS AND RESULTS: With all available data from the entire 6605-patient cohort, a prespecified Cox backward stepwise regression model identified outcome predictors, and logistic regression models examined the relation between lipid variables and AMCE risk. Baseline LDL-C, HDL-C, and apoB were significant predictors of AMCE; only on-treatment apoB and the ratio of apoB to apoAI were predictive of subsequent risk; on-treatment LDL-C was not. When event rates were examined across tertiles of baseline lipids, a consistent benefit of treatment with lovastatin was observed. CONCLUSIONS: Persons with average TC and LDL-C levels and below-average HDL-C may obtain significant clinical benefit from primary-prevention lipid modification. On-treatment apoB, especially when combined with apoAI to form the apoB/AI ratio, may be a more accurate predictor than LDL-C of risk for first AMCE.

Acute Disease↗

Neuronal damage of the substantia nigra in HIV-1 infected brains.

Extrapyramidal motor disorders are frequently noted in HIV-1-infected patients. In the present study, the substantia nigra was analyzed morphometrically to detect neuronal changes which might contribute to the pathogenetic mechanisms causing extrapyramidal motor dysfunction in HIV-1-infected patients. The numerical density and the size of pigmented, non-pigmented small, and non-pigmented large neurons in four nuclei of the substantia nigra pars compacta (antero-medial, antero-intermediolateral, postero-lateral, and postero-medial nuclei) in HIV-1-infected patients and in age-matched normal controls were determined. In HIV-1-infected brains, the numerical density of total neurons (i.e., pigmented and non-pigmented) as well as of pigmented neurons was significantly decreased, whereas that of non-pigmented neurons was not significantly changed in all investigated nuclei of the substantia nigra as compared to normal controls. A specific pattern of increase and decrease of nonpigmented large and non-pigmented small neurons was observed. The size of total neurons (pigmented and nonpigmented neurons) and of pigmented neurons was significantly reduced in all investigated nuclei of HIV-1-infected brains. The results suggest that neuronal degeneration in the substantia nigra commonly occurs and may be related to extrapyramidal symptoms in HIV-1-infected patients.

AIDS Dementia Complex↗

Amplification of a long terminal repeat-like element on the Y chromosome of the platyfish, Xiphophorus maculatus.

The platyfish (Xiphophorus maculatus), in which sex chromosomes are evident from stable and predictable inheritance of sex, is one of the best-studied lower vertebrates with respect to sex determination. In order to identify the structural equivalent for this in the karyotype, which does not contain heteromorphic pairs of chromosomes, two sex-linked molecular probes were used for fluorescent in situ hybridization analysis. One probe, derived from the melanoma oncogene locus ONC-Xmrk, stained both the X and the Y chromosome. This cytogenetic analysis mapped the sex-determining locus to the subtelomeric region of a medium-sized telocentric chromosome. Another probe, a repetitive element (XIR), specifically labeled the Y chromosome in metaphase spreads and in interphase nuclei. The sex chromosomes of X. maculatus can be considered to be at an early stage of evolution of gonosomes. Expansion of the XIR repeat is obviously one of the earliest of the molecular events that lead to divergence of the Y chromosome and recombinational isolation of the sex-determining locus.

Alleles↗

Histologically repeatedly confirmed gliosarcoma with long survival: review of the literature and report of a case.

OBJECTIVE AND IMPORTANCE: A rare case of gliosarcoma in a 61-year-old woman is presented with a stable situation over 22 years with an excellent quality of life. CLINICAL PRESENTATION: The patient was initially symptomatic and was operated on in 1975 for a deep-seated left parietal gliosarcoma. During the following 20 years, she was clinically asymptomatic until she complained of increasing headache in 1995. Neuroradiological imaging showed a sharply demarcated lesion on MRI at the former operative site, which was operated on again. Four months later, the residual tumour did grow again. INTERVENTION: As radiation therapy could not stop tumour progression and the neurological status worsened, the patient was operated on again for a massive tumour mass in the left parieto-occipital region, filling out nearly all of the previous resection cavity. Despite radio-immunotherapy, the patient finally died 22 years after the first discovery of the tumour. CONCLUSION: The present case shows that, in rare instances, gliosarcomas may show prolonged survival, although the underlying pathogenetic mechanisms for this clinical behaviour are not understood.

Brain Neoplasms↗

Application of the National Cholesterol Education Program and joint European treatment criteria and clinical benefit in the Air Force/Texas Coronary Atherosclerosis Prevention Study (AFCAPS/TexCAPS).

AIMS: The Air Force/Texas Coronary Atherosclerosis Prevention Study reported that diet with lovastatin, 20-40 mg daily, reduced the risk for a first coronary event by 37%. Because only 17% of this cohort would have qualified for drug therapy according to current U.S. guidelines, we assessed clinical benefit by risk categories. METHODS AND RESULTS: The main outcome measures were event rates of first acute major coronary events stratified by National Cholesterol Education Program and European criteria and target goal. Both those who would and would not be eligible for drug therapy, according to National Cholesterol Education Program guidelines, benefited from intervention. As expected, drug-eligible participants (event rate: lovastatin 1%/year, placebo 1.87%/year [relative risk 0.53, 95% confidence interval: 0.33, 0.84]) were at greater absolute risk for acute major coronary events than non-eligible participants (lovastatin 0.62%/year, placebo 0.93%/year [relative risk 0.67, 95% confidence interval: 0.51, 0.88]). Similar results were found using European guidelines for coronary risk management. Treatment to a target goal suggested a non-significant trend to greater benefit. CONCLUSIONS: The consistent relative benefit across risk categories suggests that it may be possible to improve identification of at-risk persons who would benefit from primary prevention, and to recommend appropriate goals of such treatment.

Aged↗

Reduction of benzodiazepine receptor binding is related to the seizure onset zone in extratemporal focal cortical dysplasia.

PURPOSE: Comparison of regional reduction of GABA receptor binding and seizure onset zone in patients with extratemporal epilepsy due to focal cortical dysplasia. METHODS: Two patients with frontal lobe epilepsy who remained seizure free after partial frontal lobe resection were investigated with magnetic resonance imaging, positron emission tomography (PET) with 18F-fluoro-deoxy-glucose (FDG) and 11C-flumazenil, subdural EEG-video recordings, and postoperative benzodiazepine (BDZ)-receptor autoradiography. RESULTS: The area of reduced BDZ-receptor binding as documented by preoperative flumazenil-PET and postoperative BDZ-receptor autoradiography corresponded to the seizure onset zone and was smaller than the interictal hypometabolism documented by FDG-PET. CONCLUSION: Flumazenil-PET is a useful tool for localization of the epileptogenic zone in patients with extratemporal epilepsy caused by focal cortical dysplasia. Neuronal distribution of BDZ-receptor density confirms in vivo flumazenil-PET findings. The regional reduction of BDZ-receptor binding in focal cortical dysplasia seems to be confined to the seizure onset zone and not to the extent of dysplastic cortex.

Adolescent↗

Air Force/Texas Coronary Atherosclerosis Prevention Study (AFCAPS/TexCAPS): baseline characteristics and comparison with USA population.

BACKGROUND: Results of the Air Force/Texas Coronary Atherosclerosis Prevention Study (AFCAPS/TexCAPS) demonstrated that treatment with lovastatin, in addition to modifications of diet and lifestyle, reduced the rate of first acute major coronary events compared with placebo in a cohort that included participants with average to mildly elevated total levels of cholesterol, and below average levels of high-density lipoprotein cholesterol, women, and elderly subjects. OBJECTIVE: To describe the baseline characteristics of the study's cohort. DESIGN: This was a double-blind, placebo-controlled, primary-prevention trial in which Americans with average to mildly elevated total levels of cholesterol [4.65-6.83 mmol/l (180-264 mg/dl)] and no clinical evidence of atherosclerotic cardiovascular disease were randomly allocated either 20-40 mg/day lovastatin or placebo in addition to a low-saturated fat, low-cholesterol diet. Baseline characteristics of the study cohort are described, and the characteristics of a USA reference population based upon NHANES III data are provided for comparison. RESULTS: The study includes 5608 men (85%) and 997 women (15%) with mean total cholesterol level 5.71 +/- 0.54 mmol/l (221 +/- 21 mg/dl), low-density lipoprotein cholesterol level 3.88 +/- 0.44 mmol/l (150 +/- 17 mg/dl), high-density lipoprotein cholesterol 0.96 +/- 0.15 mmol/l (37 +/- 6 mg/dl), and median triglyceride level 1.78 +/- 0.86 mmol/l (158 +/- 76 mg/dl). The mean age is 58 years (ranges 45-73 years for men and 55- 73 years for women). The participants are 89% white, 7% Hispanic, and 3% black. CONCLUSION: Results from AFCAPS/TexCAPS will be applicable to large segments of populations; in the USA alone, eight million share the demographic and baseline-lipid-level characteristics of the study cohort.

Aged↗

Expression of metabotropic glutamate receptor subtype mRNA (mGluR1-8) in human cerebellum.

The expression of metabotropic glutamate receptor (mGluR) mRNAs in the human cerebellar neocortex was investigated using in situ hybridization. mGluR1, 3 and 4 mRNAs were most abundant and widely distributed, whereas mGluR2, 5 and 7 mRNA expression was circumscript. mRNAs coding for mGluR1, 3, 4 and 7 were expressed in Purkinje cells. mGluR1 and 4 mRNAs detectable in granule cells and mGluR1, 2, 3, 4 and 7 mRNAs in Golgi cells. mGluR5 mRNA was detectable in putative Bergmann glia as well as mGluR3 mRNA, which was widely expressed in glial cells. mGluR8 mRNA expression was very low in a subset of stellate/basket cells of the molecular layer whereas mGluR6 mRNA was not detectable in the cerebellar cortex.

Aged↗

Streptolysin O: inhibition of the conformational change during membrane binding of the monomer prevents oligomerization and pore formation.

Streptolysin O is a four-domain protein toxin that permeabilizes animal cell membranes. The toxin first binds as a monomer to membrane cholesterol and subsequently assembles into oligomeric transmembrane pores. Binding is mediated by a C-terminally located tryptophan-rich motif. In a previous study, conformational effects of membrane binding were characterized by introducing single mutant cysteine residues that were then thiol-specifically derivatized with the environmentally sensitive fluorophoracrylodan. Membrane binding of the labeled proteins was accompanied by spectral shifts of the probe fluorescence, suggesting that the toxin molecule had undergone a conformational change. Here we provide evidence that this change corresponds to an allosteric transition of the toxin monomer that is required for the subsequent oligomerization and pore formation. The conformational change is reversible with reversal of binding, and it is related to temperature in a fashion that closely parallels the temperature-dependency of oligomerization. Furthermore, we describe a point mutation (N402E) that, while compatible with membrane binding, abrogates the accompanying conformational change. At the same time, the N402E mutation also abolishes oligomerization. These findings corroborate the contention that the target membrane acts as an allosteric effector to activate the oligomerizing and pore-forming capability of streptolysin O.

Alanine↗