Showing papers by "University of Düsseldorf published in 1996"

Moderate expansion of a normally biallelic trinucleotide repeat in spinocerebellar ataxia type 2

Abstract: The gene for spinocerebellar ataxia type 2 (SCA2) has been mapped to 12q24.1. A 1.1-megabase contig in the candidate region was assembled in P1 artificial chromosome and bacterial artificial chromosome clones. Using this contig, we identified a CAG trinucleotide repeat with CAA interruptions that was expanded in patients with SCA2. In contrast to other unstable trinucleotide repeats, this CAG repeat was not highly polymorphic in normal individuals. In SCA2 patients, the repeat was perfect and expanded to 36-52 repeats. The most common disease allele contained (CAG)37, one of the shortest expansions seen in a CAG expansion syndrome. The repeat occurs in the 5'-coding region of SCA2 which is a member of a novel gene family.

Long-term follow-up of HBeAg-positive patients treated with interferon alfa for chronic hepatitis B.

Abstract: Background In patients with chronic hepatitis B, treatment with interferon alfa and the consequent loss of hepatitis B e antigen (HBeAg) from the blood leads to a reduction in inflammatory activity, but the clinical benefits of this treatment have not been established. We evaluated whether HBeAg seroconversion induced by interferon alfa improves clinical outcome. Methods We studied prospectively a cohort of 103 patients treated with interferon alfa for chronic hepatitis B; the mean (±SD) follow-up was 50.0±19.8 months. Fifty-three untreated patients served as controls. Results After treatment with interferon alfa, 53 of 103 patients no longer had detectable HBeAg or hepatitis B virus DNA, although only 10 patients became seronegative for hepatitis B surface antigen (HBsAg) (Kaplan–Meier estimates of cumulative clearance rates at five years, 56.0 percent for HBeAg and 11.6 percent for HBsAg). Of the 53 untreated patients, only 7 spontaneously eliminated HBeAg (28.1 percent at five years), and all remained ...

Two different areas within the primary motor cortex of man

Abstract: THE primary motor area (M1) of mammals has long been considered to be structurally and functionally homogeneous1–5. This area corresponds to Brodmann's cytoarchitectural area 4. A few reports showing that arm and hand are doubly represented in M1 of macaque monkeys6,7 and perhaps man8, and that each subarea has separate connections from somatosensory areas, have, with a few exceptions9–12, gone largely unnoticed. Here we show that area 4 in man can be subdivided into areas '4 anterior' (4a) and '4 posterior' (4p) on the basis of both quantitative cytoarchitecture and quantitative distributions of transmitter-binding sites. We also show by positron emission tomography that two representations of the fingers exist, one in area 4a and one in area 4p. Roughness discrimination activated area 4p significantly more than a control condition of self-generated movements. We therefore suggest that the primary motor area is subdivided on the basis of anatomy, neurochemistry and function.

The role of cellular hydration in the regulation of cell function.

Abstract: The cellular hydration state is dynamic and changes within minutes under the influence of aniso-osmolarity, hormones, nutrients and oxidative stress. This occurs despite the activity of potent mechanisms for cell volume regulation, which have been observed in virtually all cell types studied so far. These volumeregulatory mechanisms are apparently not designed to maintain absolute cell volume constancy; rather, they act as dampeners in order to prevent excessive cell volume deviations which would otherwise result from cumulative substrate uptake. On the other hand, these volume-regulatory mechanisms can even be activated in the resting state by hormones, and by this means changes in cell hydration are created. Most importantly, small fluctuations of cell hydration, i.e. of cell volume, act as a separate and potent signal for cellular metabolism and gene expression. Accordingly, a simple but elegant method is created for the adaptation of cell function to environmental challenges. In liver, cell swelling and shrinkage lead to certain opposite patterns of cellular metabolic function. Apparently, hormones and amino acids can trigger these patterns by altering cell volume. Thus cell volume homeostasis does not simply mean volume constancy, but rather the integration of events which allow cell hydration to play its physiological role as a regulator of cell function (for reviews see [1–4]). The interaction between cellular hydration and cell function has been most extensively studied in liver cells, but evidence is increasing that regulation of cell function through alterations of cell hydration also occurs in other cell types. This review will largely refer to hepatocytes, but when appropriate other cell types will also be considered. Regulation of mitochondrial function by hormone-induced changes of matrix volume has been established in the past (for reviews see [5,6]) ; this aspect will only be covered briefly. For further details, the reader is referred to recent surveys [2,4,7,8].

Loss of disgust. Perception of faces and emotions in Huntington's disease.

Abstract: Face perception and emotion recognition were investigated in a group of people with Huntington's disease and matched controls. In conventional tasks intended to explore the perception of age, sex, unfamiliar face identity (Benton test) and gaze direction from the face, the Huntington's disease group showed a borderline impairment of gaze direction perception and were significantly impaired on unfamiliar face matching. With a separate set of tasks using computerinterpolated ('morphed') facial images, people with Huntington's disease were markedly impaired at discriminating anger from fear, but experienced less difficulty with continua varying from male to female, between familiar identities, and from happiness to sadness. In a further test of recognition of facial expressions of basic emotions from the Ekman and Friesen (1976) series, interpolated images were created for six continua that lay around the perimeter of an emotion hexagon (happiness-surprise; surprise-fear; fear-sadness; sadness-disgust; disgust-anger; anger-happiness). In deciding which emotion these morphed images were most like, people with Huntington's disease again showed deficits in the recognition of anger and fear, and an especially severe problem with disgust, which was recognized only at chance level. A follow-up study with tests of facially and vocally expressed emotions confirmed that the recognition of disgust was markedly poor for the Huntington's disease group, still being no better than chance level. Questionnaires were also used to examine self-assessed emotion, but did not show such striking problems. Taken together, these data reveal severe impairments of emotion recognition in Huntington's disease, and show that the recognition of some emotions is more impaired than others. The possibility that certain basic emotions may have dedicated neural substrates needs to be seriously considered: among these, disgust is a prime candidate.

Altered Expression of hMSH2 and hMLH1 in Tumors with Microsatellite Instability and Genetic Alterations in Mismatch Repair Genes

Abstract: To date, at least four genes involved in DNA mismatch repair (MMR) have been demonstrated to be altered in the germline of patients with hereditary nonpolyposis colon cancer: hMSH2, hMLH1, hPMS1, and hPMS2. Additionally, loss of MMR function has been demonstrated to lead to the phenomenon of microsatellite instability (MIN) in tumors from these patients. In this study, we have examined the protein expression pattern of hMSH2 and hMLH1 by immunohistochemistry in paraffin-embedded tumors from 7 patients with MIN+ sporadic cancer, 13 patients with familial colorectal cancer, and 12 patients meeting the strict Amsterdam criteria for hereditary nonpolyposis colon cancer. The relationship between the expression of these two gene products, the presence of germline or somatic mutations, and the presence of tumor MIN was examined. Nineteen of the 28 tumors studied demonstrated MIN, whereas mutations in hMLH1 and hMSH2 were detected in 6 and 2 patients, respectively. Of the eight MIN+/mutation+ cases, the absence of protein expression was observed for the corresponding gene product in all but one case (missense mutation in hMLH1). However, seven MIN+/mutation- cases also showed no expression of either hMLH1 (n = 5), hMSH2 (n = 1), or both (n = 1), whereas four MIN+/mutation- cases demonstrated normal expression for both. None of the MIN-/mutation- cases (n = 9) demonstrated an altered expression pattern for either protein. These data suggest that examination of protein expression by immunohistochemistry may be a rapid method for prescreening tumors for mutations in the MMR genes.

Stable nuclear transformation of the diatom Phaeodactylum tricornutum.

Abstract: A nuclear transformation system has been developed for the diatomPhaeodactylum tricornutum using microparticle bombardment to introduce thesh ble gene fromStreptoalloteichus hindustanus into cells. Thesh ble gene encodes a protein that confers resistance to the antibiotics Zeocin and phleomycin. Chimeric genes containing promoter and terminator sequences from theP. tricornutum fcp genes were used to drive expression ofsh ble. Between 10–100 transformants were recovered/108 cells. Transformants were able to grow on at least 500 µg/ml of Zeocin, which is 10 times the amount necessary to kill wild-type cells. Based on Southern hybridizations thesh ble gene was present in 1–3 copies/transformant. Relative levels of correctly processed transcripts were correlated with the abundance of the Sh ble protein (present at 0.1–2.0 µg/mg total protein). Thecat reporter gene fused to afcp promoter could also be introduced by microparticle bombardment and was found to be highly expressed (average of 7.1 U/mg total protein). This work demonstrates that heterologous genes can be readily expressed inP. tricornutum. The development of selectable marker and reporter gene constructs provides the tools necessary for dissecting gene structure and regulation, and introducing novel functions into diatoms.

Neuronal hyperexcitability and reduction of GABAA-receptor expression in the surround of cerebral photothrombosis.

Abstract: Changes of neuronal excitability and γ-aminobutyric acid (GABAA)-receptor expression were studied in the surround of photothrombotic infarcts, which were produced in the sensorimotor cortex of the rat by using the rose bengal technique. In a first series of experiments, multiunit recordings were performed on anesthetized animals 2–3 mm lateral from the lesion. Mean discharge frequency was considerably higher in recordings from lesioned animals (>100 Hz in the first postlesional week) compared with control animals (mean, 15 Hz). These alterations were already present after 1 day but were most pronounced 3 to 7 days after lesion induction. Thereafter the hyperexcitability declined again, although it remained visible up to 4 months. In a second series of experiments, the GABAA-receptor expression was studied autoradiographically. This revealed a reduction of GABAA receptors in widespread brain areas ipsilateral to the lesion. The reduction was most pronounced in the first days after lesion induction and decl...

Averaged pulse dynamics in a cascaded transmission system with passive dispersion compensation

Abstract: A theory of optical pulse propagation in cascaded transmission systems that are based on the dispersion-compensating fiber technique is developed. The existence of two scales associated with fiber dispersion and system residual dispersion leads to a simple model for the averaged pulse dynamics. In the particular case of practical importance, the averaged pulse dynamics is governed by the nonlinear Schrodinger equation. The pulse transmission stability is examined.

Thalamic metabolism and corticospinal tract integrity determine motor recovery in stroke

Abstract: We studied the role of remote metabolic depressions and pyramidal tract involvement regarding motor recovery following a first hemiparetic ischemic stroke. In 23 patients the regional cerebral glucose metabolism (rCMRGlu) was measured with positron emission tomography and the location and spatial extent of the stroke lesions were assessed by magnetic resonance imaging. Motor impairment during the acute and chronic stages (4 weeks after stroke) was determined by a motor score and recordings of magnetic evoked motor potentials. Twelve patients recovered significantly, whereas 11 patients retained a disabling hemiparesis. In contrast to patients with good motor recovery, rCMRGlu was severely depressed in the thalamus on the lesion side in patients with poor motor recovery. This patient group also showed more severe damage to the pyramidal tract on magnetic resonance images and a more pronounced reduction of the magnetic evoked motor potential amplitude. Neither the size of the stroke lesions nor the spatial extent of the lesional and remote rCMRGlu depressions outside the thalamus correlated with the thalamic hypometabolism and the improvement of the motor score. We conclude that preservation both of parts of the pyramidal tract and of the thalamic circuitry is a major determinant for the quality of hand motor recovery following acute brain ischemia in the adult.

Atypical X-Linked Severe Combined Immunodeficiency Due to Possible Spontaneous Reversion of the Genetic Defect in T Cells

Abstract: X-linked severe combined immunodeficiency is a recessive hereditary disease characterized by severe and persistent infections starting in the first months of life and associated with diarrhea and failure to thrive.1 Affected infants almost invariably present with an absence of T cells and natural killer cells, normal or elevated B-cell counts, and hypogammaglobulinemia. This disease is rapidly fatal without bone marrow transplantation.2 The disease locus has been mapped to Xq12–13,3 and the genetic defect identified as a mutation of the γ chain of the interleukin-2 receptor,4 which has been cloned and was recently renamed the common γ (γc) chain because of . . .

Low Increase in cGMP Induced by Organic Nitrates and Nitrovasodilators Improves Contractile Response of Rat Ventricular Myocytes

Abstract: Whether organic nitrates are bioactivated to NO in cardiac muscle cells and may thus directly affect cardiac contractile function has remained an open question. Therefore, we determined the effects of the organic nitrates glyceryl trinitrate (100 μmol/L), pentaerythritol tetranitrate (10 μmol/L), and isosorbide-5-mononitrate on electrically stimulated contractile response (CR) and cAMP and cGMP content of isolated adult rat ventricular cardiomyocytes compared with different concentrations of the spontaneous NO donors S -nitroso- N -acetyl-d,l-penicillamine (SNAP) and 2,2-diethyl-1-hydroxy-1-nitroso-hydrazine (DEA/NO). A high concentration of spontaneous NO donors (100 μmol/L) caused a large increase in cGMP content that was accompanied by a decrease in CR to 73.8±6.7% (SNAP) and 80.9±6.1% (DEA/NO) of the control values. Inhibition of cGMP-dependent protein kinase by 10 μmol/L KT 5822 converted this effect into a pronounced improvement of CR (163.5±14.0%). By contrast, the organic nitrates caused a small but significant increase in cGMP, which was accompanied by an increase in cAMP and CR identical to that induced by 10 nmol/L isoprenaline (141.6±6.4%). A similar effect was observed with a low concentration (1 μmol/L) of SNAP and DEA/NO. All increases in CR induced by nitrates were abolished after inhibition of cAMP-dependent protein kinase by Rp-cAMPS (10 μmol/L). The positive contractile effect of isoprenaline was enhanced by 1 μmol/L SNAP. This effect was also demonstrated in isolated rat papillary muscles. These results indicate that in cardiac muscle (1) organic nitrates are bioactivated to NO; (2) this results in a moderate increase in cGMP, which causes an improved CR by increasing cAMP and activating cAMP-dependent protein kinase; and (3) a large increase in cGMP, produced by high doses of NO donors, reduces CR because of the activation of cGMP-dependent protein kinase.

Microsatellite Instability and Mutation Analysis of hMSH2 and hMLH1 in Patients with Sporadic, Familial and Hereditary Colorectal Cancer

Abstract: To date, at least four genes involved in DNA mismatch repair, hMSH2, hMLH1, hPMS1 and hPMS2, have been demonstrated to be altered in the germline of patients with hereditary nonpolyposis colorectal cancer (HNPCC). Additionally, defective mismatch repair is thought to account for the observation of microsatellite instability (MIN) in tumors from these patients. The genetic defect responsible for the MIN+ phenotype in sporadic colorectal cancer, however, has yet to be clearly delineated. In order to better understand the role of somatic and germline alterations within hMSH2 and hMLH1 in the process of colorectal tumorigenesis, we examined the entire coding regions of both of these genes in seven patients with MIN+ sporadic colorectal cancer, 19 patients with familial colorectal cancer, and 20 patients meeting the strict Amsterdam criteria for HNPCC. Thirteen germline, two somatic, and four neutral alterations were identified. The two somatic mutations occurred in patients having familial cancer, while the germline mutations were distributed among one sporadic (14%), three familial (16%), and nine HNPCC (45%) cases. All patients with identified mutations in the mismatch repair genes, whose tumors were available for analysis, demonstrated MIN. On the other hand, we could not identify mutations in the subset of clinically defined HNPCC patients with MIN negative tumors nor in the majority (6/7) of MIN+ sporadic tumors.

Difference in leptin mRNA levels between omental and subcutaneous abdominal adipose tissue from obese humans.

Abstract: Differences in fat cell size and function among adipose tissue depots are well known and may be important in the pathophysiology of the metabolic and cardiovascular complications of obesity. Since the newly discovered adipocyte hormone leptin is thought to be a central factor in the regulation of energy homeostasis, it may be interesting to know if there are regional differences in leptin production. The aim of this study was to compare the level of leptin expression in the omental and subcutaneous abdominal adipose tissue from obese humans. Adipose tissue samples were collected from 25 severely obese adults (mean BMI: 48.9 +/- 9.7 kg/m2) undergoing vertical gastric banding. Semi-quantitative determination of leptin mRNA by the RT-PCR technique showed significantly lower leptin expression in omental compared to subcutaneous abdominal adipose tissue (leptin/Sp1 ratio in omental vs. subcutaneous fat: 1.53 +/- 0.89 vs. 3.02 +/- 1.58, p < 0.01). Identical results were obtained when Northern blotting was applied in a subgroup. Leptin expression increased with age in omental adipose tissue (r = 0.42, p < 0.05), but not in subcutaneous tissue. No correlation was found between BMI or waist/hip ratio (WHR) and leptin expression in omental or subcutaneous adipose tissue. The regional difference in leptin expression was similar in the patients with impaired glucose tolerance/type-2 diabetes and those with normal glucose tolerance. In conclusion, the results of this study indicate that leptin expression is lower in omental than subcutaneous adipose tissue, possibly due to differences in fat cell size and/or sympathetic innervation.

The Alzheimer's disease-associated presenilins are differentially phosphorylated proteins located predominantly within the endoplasmic reticulum.

Abstract: Alzheimer’s disease (AD) is a progressive neurodegenerative disorder characterized by the deposition of extracellular senile plaques composed of amyloid β-peptide (Aβ). Whereas most cases of AD occur sporadically, about 10% of AD cases are inherited as a fully penetrant autosomal dominant trait. Mutations in the recently cloned Presenilin genes (PS-1 and PS-2) are by far the most common cause of early onset familial AD. Cellular expression of endogenous and overexpressed PS proteins was analyzed by immunocytochemistry and metabolic labeling followed by immunoprecipitation. In vivo phosphorylation sites of PS proteins were analyzed by extensive mutagenesis. PS-1 as well as PS-2 proteins were localized predominantly within the endoplasmic reticulum (ER). However, small amounts of the PS proteins were detected within the Golgi compartment, where they colocalize with the β-amyloid precursor protein (βAPP). The PS-2 protein was found to be highly phosphorylated. whereas very little phosphorylation was observed for PS-1. The selective phosphorylation of PS-2 occurs exclusively on serine residues. In vivo phosphorylation of PS-2 was mapped to serine residues 7, 9, and 19 within an acidic stretch at the N terminus, which is absent in PS-1. Casein kinase (CK)-l and CK-2 were shown to phosphorylate the N terminus of PS-2 in vitro. The majority of PS proteins were detected in the ER where little if any proteolytic processing of βAPP was reported. ER retention of PS proteins might occur by intramolecular aggregation. Small amounts of PS proteins were also detected in the Golgi where they colocalized with βAPP. This might suggest that potential interactions between PS proteins and βAPP could occur within the Golgi. Selective phosphorylation of PS-2 proteins within the acidic domain missing in PS-1 indicates differences in the biological functions and regulation of the two highly homologous proteins.

Electrophysiological Transcortical Diaschisis After Cortical Photothrombosis in Rat Brain

Abstract: Background and Purpose The severity of functional deficits after a cortical infarction often does not correlate with lesion size. The stroke may affect pathways connecting to distant brain regions and therefore may also alter the function of remote parts of the cortex. Remote changes in electric activity, blood flow, and metabolism are called diaschisis. In the present study we addressed the question of whether in brain areas contralateral to a photochemically induced cortical infarction alteration of excitability can be observed as an indication of the effects of diaschisis. Methods We induced focal lesions in the sensory area at the border of the motor and occipital cortices by injecting the photosensitizing dye rose bengal and illuminating the skull stereotaxically. Seven days after induction of photothrombosis, electrophysiological recordings were obtained with standard methods from 400-μm-thick neocortical coronal slices. As an indication of inhibition we used a paired-pulse stimulus protocol and cal...

Intrinsic optical signals in rat neocortical slices measured with near- infrared dark-field microscopy reveal changes in extracellular space

Abstract: In the last decade, the measurement of activity-dependent intrinsic optical signals (IOSs) in excitable tissues has become a useful tool for collecting data about spatial patterns of information processing in mammalian brain and spread of excitation. Although the extent of the IOS correlates well with the extent of electrical excitation, its time course is much slower, suggesting that it does not directly monitor the electrical activity. The aim of this study was to investigate the mechanisms responsible for generation of IOSs. Coronal neocortical brain slices of juvenile rats were electrically stimulated at the border of layer VI and the white matter. The induced columnar-shaped IOSs were recorded using dark-field video microscopy. At corresponding locations, alterations in extracellular K+ concentration and extracellular space (ECS) volume were registered using ion-selective microelectrodes. After stimulation, a transient increase of extracellular K+ concentration up to 10 mM and a transient decrease of ECS volume by approximately 4% could be observed. The comparison of the time courses of these parameters yielded considerable differences between extracellular K+ concentration increase and IOS, but obvious similarities between alterations in ECS volume and IOS. To test the hypothesis that changes in IOS reflect changes in ECS, but not extracellular K+ concentration, we recorded under conditions that are known to prevent activity-induced changes in ECS, i.e., in low Cl- solutions and in the presence of furosemide. Both treatments similarly decreased stimulation-induced IOSs and alterations of ECS. However, the effect of these treatments on changes of extracellular K+ was different and did not correspond to the changes of IOS. We conclude that activity-dependent IOSs in rat neocortical slices measured by near-infrared video microscopy reveal changes in ECS. Furthermore, the pharmacological and ion substitutional experiments make it likely that activity-induced IOSs are attributable to cell swelling via a net KCI uptake and a concomitant water influx.

Combined chemokine and cytokine gene transfer enhances antitumor immunity.

Abstract: The probability of producing a specific antitumor response should be increased by multiplying the number of T lymphocytes that encounter the malignant cells. We tested this prediction in a murine model, using a recently discovered T-cell chemokine, lymphotactin (Lptn). This chemokine increased tumor cell infiltration with CD4+ lymphocytes but generated little antitumor activity. Coexpression of the T-cell growth factor interleukin-2, however, greatly expanded the T lymphocytes attracted by Lptn, affording protection from the growth of established tumor in a CD4+ and CD8+ T cell-dependent manner. Lesser synergy was seen with GM-CSF. Hence coexpression of a T-cell chemokine and T-cell growth factor potentiates antitumor responses in vivo, suggesting a general strategy to improve cancer immunotherapy.

Isolation of high-chlorophyll-fluorescence mutants of Arabidopsis thaliana and their characterisation by spectroscopy, immunoblotting and northern hybridisation

Abstract: Thirty-four recessive photosynthetic mutants of the high-chlorophyll-fluorescence (hcf) phenotype have been isolated by screening 7700 M2 progenies of ethyl methane sulfonate-treated seeds ofArabidopsis thaliana. Most of the mutants isolated were found to be seedlinglethal, but could be grown on sucrose-supplemented media. Chlorophyll (Chl) fluorescence induction, absorption changes in the reaction-centre chlorophyll of PS I (P700) at 830 nm and Chla/Chlb ratios were recorded in order to probe the photosynthetic functions and to define the mutational lesion. These studies were complemented by immunoblot and Northern analyses which finally led to the classification of the mutants into six different groups. Four classes of mutants were affected in PS I, PS II (two different classes) or the intersystem electron-transport chain, respectively. A fifth mutant class was of pleiotropic nature and the sixth class comprised a Chlb-deficient mutant. Several of the mutants showed severe deficiencies in the levels of subunits of PS I, PS II or the cytochromeb 6/f complex. Thus the mutational lesions could be located precisely. Only one mutant was defective in the transcript patterns of some plastid-encoded photosynthesis genes. Hence most of the mutants isolated appear to be affected in translational and post-translational regulatory processes of thylakoid membrane biogenesis or in structural genes encoding constituent subunits of the thylakoid protein complexes.

Assessing the „humorous temperament“: Construction of the facet and standard trait forms of the State-Trait-Cheerfulness-Inventory — STCI

Abstract: The present paper outlines the relevance of cheerfulness, seriousness, and bad mood for humor research. A state-trait model of exhtiaratability is presented which incorporates the three concepts as both states and traits. Definitions of the concepts are undertaken utilizing a facet approach and the relationships among the three concepts are outlined. The construction strategy for the various forms of the German Version of the State-Trait- Cheerfulness-Inventory (STCI) is outlined and the following versions of the trait form will be elaborated: (a) the pilot form with 122 items (STCI-T ); (b) a component (or long) form with 106 items (STCI-T ); (c) the Standard form with 60 items (STCI-T ) and (d) the international form with 106 items (STCI-T ). The development ofthe twoforms, the replication ofthepsychometric character- istics, and the evaluation of the facet model utilized samples of German and American adults comprising more that 1,300 subjects altogether. The hypothesized facet structure emerged and appeared to be highly generaliz- able across the samples. The psychometric characteristics ofthe facets and scales appeared to be satisfactory. While there were no sex differences in any of the scales, seriousness increased steadily ofter age 40. Correspondence between seif· and peer-evaluation was examinedand turned out to be sufficiently high. The construction seemed to have been successful in promding a reliable Instrument for the assessment ofthe temperamental basis ofthe sense of humor.