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M Wilke

Publications and source records attributed to M Wilke.

At least 37 records · Page 2Linked to original sources
PubMed2001

Gray matter-changes and correlates of disease severity in schizophrenia: a statistical parametric mapping study.

Voxel-based morphometry has recently been used successfully to detect gray matter volume reductions in schizophrenic patients. The aim of the present study was to confirm the findings on gray-matter changes and to complement these by applying the methodology to CSF-differences. Also, we wanted to determine whether a correlation exists between a clinically defined parameter of disease severity and brain morphology in schizophrenic patients. We investigated 48 schizophrenic patients and compared them with 48 strictly age- and sex-matched controls. High-resolution whole-brain MR-images were segmented and analyzed using SPM99. In a further analysis, the covariate effect of the global assessment of functioning-score (GAF) was calculated. Main findings were (i) left-dominant frontal, temporal, and insular GM-reductions and (ii) GM-increases in schizophrenic patients in the right basal ganglia and bilaterally in the superior cerebellum; (iii) CSF-space increases in patients complementary to some GM-reductions; (iv) a correlation between the GAF-score and local GM-volume in the left inferior frontal and inferior parietal lobe of schizophrenic patients. This study confirms and extends some earlier findings on GM-reduction and detected distinct GM-increases in schizophrenic patients. These changes were corroborated by complementary CSF-increases. Most importantly, a correlation could be established between two particular gray matter-regions and the overall disease severity, with more severely ill patients displaying a local GM-deficit. These findings may be of potentially large importance for both the future interpretation and design of neuroimaging studies in schizophrenia and the further elucidation of possible pathophysiological processes occurring in this disease.

Adult↗
PubMed2001

MR diffusion imaging and 1H spectroscopy in a child with medulloblastoma. A case report.

We report on a child with a metastasising medulloblastoma which was assessed by MR diffusion imaging and 1H MR spectroscopy (MRS). Reduced mean apparent diffusion coefficients and a high amount of taurine could be demonstrated. This is the first reported case of high taurine in medulloblastoma in vivo and confirms earlier in vitro findings. It is suggested that the changes on diffusion imaging, possibly reflecting the small-cell histology of the tumour and high taurine in MRS, are indicative of medulloblastoma.

Aspartic Acid↗
PubMed2001

Development of a technique for transcervical collection of uterine tissue in bitches.

Transcervical collection of endometrial tissue specimens is a valuable and well established tool for the diagnosis of reproductive disorders in cows, mares and women, but it is not used currently in bitches. Endometrial biopsy samples were collected by transcervical cannulation from the cranial uterine body at defined stages of the oestrous cycle using biopsy forceps. In study 1, the histology of 45 biopsy specimens taken from 23 Beagle bitches were compared with larger tissue samples collected post mortem. For further evaluation of representative biopsy specimens, the expression of oestrogen and progesterone receptors was determined. Only 31.1% of the biopsy samples taken from bitches could be evaluated and they showed stroma, capillaries, luminal epithelium, glandular ducts and apical glands; however, basal glands and myometrium were not observed. Biopsy findings were in agreement with the diagnosis of the uterine specimens concerning endometrial differentiation, inflammatory and degenerative lesions. The expression of oestrogen and progesterone receptors was slightly lower in the biopsy samples. In study 2, a total of 49 serial biopsy samples were taken from 12 Beagle bitches. In eight bitches, the manipulation resulted in a haemomucometra. Treatment with PGF2 alpha and antibiotics led to a clinical cure in five of these dogs, two of which were mated successfully during the next oestrus. Three animals had to undergo ovariohysterectomy. Owing to the small proportion of biopsy specimens that was suitable for analysis and the high risk of biopsy-related endometritis, transcervical biopsy collection cannot be recommended as a routine technique in bitches.

Animals↗
PubMed2000

Introduction and evaluation of a modular seminar system in gross anatomy teaching at the Hannover Medical School.

We present a new modular seminar system which has been introduced into the gross anatomy teaching at the Hannover Medical School. It consists of seven modules with a clinical emphasis. The new modular seminar system was evaluated by an anonymous questionnaire. The results showed that the seminar system as a whole, and the different modules with one exception were highly appreciated by the students. The evaluation also revealed that the main reason for the success of a module is the manner of the teaching and learning rather than the clinical relevance. Taking into account the results of this evaluation we describe the appropriate style of teaching for use in a seminar. The success of this new approach to small group instruction in Germany should encourage other teachers of anatomy and other undergraduate subjects to consider new methods of teaching.

Anatomy↗
PubMed2000

Primarily chronic and cerebrovascular course of Lyme neuroborreliosis: case reports and literature review.

As part of an ongoing study aiming to define the clinical spectrum of neuroborreliosis in childhood, we have identified four patients with unusual clinical manifestations. Two patients suffered from a primarily chronic form of neuroborreliosis and displayed only non-specific symptoms. An 11 year old boy presented with long standing symptoms of severe weight loss and chronic headache, while the other patient had pre-existing mental and motor retardation and developed seizures and failure to thrive. Two further children who presented with acute hemiparesis as a result of cerebral ischaemic infarction had a cerebrovascular course of neuroborreliosis. One was a 15 year old girl; the other, a 5 year old boy, is to our knowledge the youngest patient described with this course of illness. Following adequate antibiotic treatment, all patients showed substantial improvement of their respective symptoms. Laboratory and magnetic resonance imaging findings as well as clinical course are discussed and the relevant literature is reviewed.

Adolescent↗
PubMed2000

[Guidelines of the Spanish Society of Cardiology for clinical practice in exercise testing].

Most exercise testing is performed in adults with known or suspected ischemic heart disease. In the last few years cardiac imaging techniques have been applied in this field, improving the information obtained with the procedure. However, the exceptions to this rule are emerging rapidly not only in healthy people (asymptomatic individuals, athletes, handicapped people) but also in cardiac patients (advanced congestive heart failure, hypertension, rhythm disorders, congenital heart disease, etc.). All the-se issues justify the need for a multidisciplinary consensus document in Spain. This paper reviews and updates the methodological aspects of the stress test, including those related to oxygen consumption measurements. The main aim of this review was to determine the role of exercise testing in the evaluation of ischemic heart disease as well as the applications of imaging stress testing. The usefulness of this test in other non-ischemic cardiac disorders and in selected subsets of healthy people is also reviewed.

Adult↗
PubMed1998

Genomic identification of the minor histocompatibility antigen HA-1 locus by allele-specific PCR.

Graft-versus-host disease (GvHD) can be a major complication of allogeneic bone marrow transplantation even in recipients of HLA genotype-identical transplants. Disparities in minor histocompatibility antigens (mHags) between donor and recipient are a potential risk for the development of GvHD. A mismatch for the mHag HA-1 can cause GvHD in adult recipients of allogeneic bone marrow from HLA-identical donors. The mHag HA-1, first identified by HLA-A*0201-restricted cytotoxic T cells (CTLs), was recently chemically characterized as a nonapeptide. On the cDNA level, the HA-1 locus has two alleles, HA-1H and HA-1R, which differ in two nucleotides, resulting in a single amino acid substitution. Here we report on the genomic structure of the HA-1 locus. Isolation and sequencing of cosmid DNA encoding the HA-1 peptide sequence revealed that the HA-1 alleles are encoded by two exons. Two different primer sets were designed, each consisting of allele-specific primers and a common primer, and both sets containing intronic sequences. We performed genomic DNA typing of three families consisting of 24 HLA-A*0201-positive individuals. The predicted allele-specific products correlated in all cases with the mHag classification by CTLs and by RT-PCR. We demonstrate for the first time the genomic identification of the mHag HA-1 locus. Prospective genomic typing for the HA-1 alleles will improve donor selection and identify HLA-A*0201-positive recipients with a high risk for HA-1-induced GvHD.

Adult↗
PubMed1997

Complementation of the genetic defect in Gunn rat hepatocytes in vitro by highly efficient gene transfer with cationic liposomes.

In this article, we report complementation of the genetic defect of isolated Gunn rat hepatocytes by a highly efficient method for lipofection. Transfections were performed 24 h after plating by using the cationic liposome DOTAP. On average, transfection efficiencies of 21% lacZ+ cells with Wag/Rij rat cells and 27% lacZ+ cells with Gunn rat cells could be obtained when the parenchymal cells were transfected in a hormone-defined, serum-free medium. LacZ expression vectors with the CMV promoter were more effective than constructs containing the RSV or the TK promoter. A linear relationship between the viability of hepatocytes after isolation and the percentage of lacZ+ cells was observed with both rat strains, with a maximum of 40% lacZ+ cells at a viability of 94%. The transfection efficiencies were significantly lower in the absence of growth factors, in dexamethasone-containing medium, or when serum was present during plating. Our data are consistent with the assumption that a mitotic event is required for efficient lipofection. Bilirubin conjugation activity could be detected in microsomes from Gunn rat hepatocytes after transfection with two different B-UDPGT expression constructs. Highest conjugation activity was achieved with a vector containing a terminal intron. With this construct on average 4% of the bilirubin conjugation activity of normal human liver microsomes could be achieved in total microsomes of transfected Gunn rat hepatocytes. The implications of our data for gene therapy of hepatic disease with nonviral vectors, in particular bilirubin conjugation deficiency (Crigler-Najjar disease) are discussed.

Animals↗
PubMed1997

Characterization of a large transferrin-binding protein from Actinobacillus pleuropneumoniae serotype 7.

The binding of transferrin at the surface of Actinobacillus pleuropneumoniae (A. pp.) is mediated by two proteins of approximately 60 and 100 kDa. The 60 kDa protein has been shown to be highly divergent among different serotypes and to induce a serotype-specific protective immune response. In this study we have characterized the 100 kDa transferrin-binding protein of A. pp. serotype 7 and designated it as TfbB. The tfbB gene was found to be located immediately downstream of the tfbA gene. It was cloned and sequenced, and antibodies raised against the isolated recombinant protein detected, with a constant intensity, a 100 kDa protein in A. pp. serotypes 2, 4, 6, 7, 8, 9, 10 and 11, and a polypeptide of approximately 103 kDa in serotypes 1, 3, 5A and 12. In addition, comparative analysis of the deduced amino acid sequence showed more than 40% identity with the large transferrin-binding proteins of Neisseria meningitidis and Haemophilus influenzae. The TfbB protein was expressed in E. coli outer membranes in a conformation eliciting porcine transferrin-specific binding activity. Sera of pigs immunized with these TfbB-containing E. coli membranes recognized functional membrane-associated TfbB protein whereas no such reaction was observed upon immunization with isolated recombinant TfbB protein. A preliminary animal experiment showed that TfbB-containing outer membrane preparations from recombinant E. coli can reduce significantly the mortality of an A.pp. infection with the homologous strain.

Actinobacillus pleuropneumoniae↗
PubMed1996

Efficacy of a peptide-based gene delivery system depends on mitotic activity.

We have developed and tested a transfection compound based on synthetic peptides. It consists of a 12 amino acid DNA binding peptide (P2) with an alkyl group added to the aminoterminus (P2lip) and a peptide derived from the hemagglutinin protein (HA). The components aggregate spontaneously to particles that proved to be an efficient, easy to use and chemically stable transfection compound. With this system we found a marked correlation between transfection efficiency and mitotic activity. Cells that are allowed to perform a mitosis after exposure to either DNA-P2lip/HA or DNA-cationic liposome complexes are transfected much more efficiently than cells arrested in the cell cycle. In search of an explanation for this phenomenon we studied transport of plasmid DNA across the nuclear membrane. Plasmid DNA injected into the cytoplasm of quiescent human fibroblasts is not expressed, in contrast to DNA injected into the nucleus. FISH analysis showed that the plasmid DNA is not transported into the nucleus efficiently. Similarly, DNA-P2lip/HA complexes are readily taken up by both proliferating and nonproliferating cells, but do not readily penetrate the nuclear membrane. We conclude that delivery of plasmid DNA to the cytoplasm is not sufficient for transfection of eukaryotic cells. The nuclear membrane is apparently an important barrier. This explains why a mitotic event is required for efficient transfection with the currently available transfection systems. The implications for the further development of transfection compounds for use in vivo, where nonproliferating cells are often the target, are discussed.

Biological Transport↗
PubMed1995

Positional mapping of loci in the DiGeorge critical region at chromosome 22q11 using a new marker (D22S183).

The majority of patients with DiGeorge syndrome (DGS) and velo-cardio-facial syndrome (VCFS) and a minority of patients with non-syndromic conotruncal heart defects are hemizygous for a region of chromosome 22q11. The chromosomal region that is commonly deleted is larger than 2 Mb. It has not been possible to narrow the smallest region of overlap (SRO) of the deletions to less than ca 500 kb, which suggests that DGS/VCFS might be a contiguous gene syndrome. The saturation cloning of the SRO is being carried out, and one gene (TUPLE1) has been identified. By using a cosmid probe (M51) and fluorescence in situ hybridization, we show here that the anonymous DNA marker locus D22S183 is within the SRO, between TUPLE1 and D22S75 (probe N25). A second locus with weak homology to D22S183, recognized by cosmid M56, lies immediately outside the common SRO of the DGS and VCFS deletions, but inside the SRO of the DGS deletions. D22S183 sequences are strongly conserved in primates and weaker hybridizing signals are found in DNA of other mammalian species; no transcripts are however detected in polyA+ RNA from various adult human organs. Probe M51 allows fast reliable screening for 22q11 deletions using fluorescence in situ hybridization. A deletion was found in 11 out of 12 DGS patients and in 3 out of 7 VCFS patients. Two patients inherited the deletion from a parent with mild (atypical) symptoms.

Abnormalities, Multiple↗
PubMed1993

Low-conductance chloride channels in IEC-6 and CF nasal cells expressing CFTR.

The properties of the cystic fibrosis gene product (CFTR) were studied by expression of cloned cDNA in different cell systems. Infection of both simian fibroblast (Vero) cells and immortalized CF nasal polyp cells (NCF3A) with a vaccinia virus encoding CFTR induced forskolin-induced Cl- permeability and low-conductance (8 pS) Cl- channels. By stable transfection of the rat intestinal crypt-derived cell line IEC-6 we have isolated a clone, IEC-CF7, which expresses CFTR mRNA and antigen. IEC-CF7 cells, but not IEC-6, display forskolin-induced Cl- permeability and multiple linear low-conductance (+/- 8 pS) Cl- channels in cell-attached membrane patches. In excised patches of IEC-CF7 cells, low-conductance Cl- channels could be activated by addition of the catalytic subunit of the adenosine 3',5'-cyclic monophosphate-dependent protein kinase A (PKA) plus ATP. During bath fluid replacement studies, the activated low-conductance channel remained active in the absence of ATP at room temperature and showed saturation kinetics. Rectifying (32 pS) Cl- channels were not observed in either IEC-6 cells or IEC-CF7 cells, indicating that there is no relation between CFTR expression and the incidence of this channel. Our data strongly support the conclusion that CFTR can act as a low-conductance Cl- channel, gated by PKA. The IEC-6-derived cell line IEC-CF7 may prove to be a useful model in the study of CFTR function because of the absence of 32-pS Cl- channel activity and its potential for differentiation.

Adenosine Triphosphate↗
PubMed1992

Amphotropic retroviruses with a hybrid long terminal repeat as a tool for gene therapy of cystic fibrosis.

We have made two retroviral vectors encoding the bacterial beta-galactosidase (lacZ) as a marker gene and a long terminal repeat (LTR) containing an enhancer of the polyoma F101 virus [symbol: see text]. One vector, [symbol: see text], can be used as a test vector in grafting, lineage analysis and gene therapy studies. The other, [symbol: see text] carries an additional unique cloning site in which a gene of interest can be cloned. Titration experiments showed that in human epithelial cell lines, [symbol: see text] produces a transcriptionally active integration more often than the commonly used BAG vector with the wild type LTR. Human epithelial cells in primary culture could be successfully infected. Our data suggest that gene therapy protocols requiring infection in situ, such as in the case of cystic fibrosis, will be hampered by the relatively low local titres that can be achieved at present.

Cell Line↗
PubMed1992

Quantitative expression patterns of multidrug-resistance P-glycoprotein (MDR1) and differentially spliced cystic-fibrosis transmembrane-conductance regulator mRNA transcripts in human epithelia.

P-glycoprotein (MDR1), that confers multidrug resistance in cancer, and the cystic-fibrosis transmembrane-conductance regulator (CFTR), that is causative defective in cystic fibrosis, belong to the family of ATP-binding transport proteins. The expression of MDR1 and CFTR in human epithelial tissues and the cell lines T84 and HT29 was estimated by primer-directed reverse transcription (RT) and subsequent monitoring of the kinetics of cDNA product formation during the polymerase chain reaction (PCR). MDR1 mRNA was found in high levels, 15-50 amol mRNA/microgram RNA, in the intestine, kidney, liver and placenta, and in low levels, 0.2 amol/microgram RNA, in respiratory epithelium. Large amounts of CFTR mRNA were measured in the gastrointestinal tract, whereas the kidney, as the phenotypically normal organ, and the lung, as the most severely affected organ in cystic fibrosis, both contained low amounts, 3 amol CFTR/microgram RNA. CFTR transcript levels of 1-5 amol/microgram RNA were determined in lymphocytes and lymphoblast cell lines, suggesting that lymphoblasts are an accessible source for the study of the molecular pathogenesis of cystic fibrosis. When transcripts were scanned by overlapping RT/PCR analyses, only transcript of expected size was detected for MDR1 mRNA, where variable in-frame deletions of either exon 4, 9 or 12 were observed in CFTR mRNA. The complete loss of single exons was seen at proportions of 1-40% in all investigated tissues and cell lines with large donor-to-donor variation. Exons 9 and 12 of the CFTR gene encode parts of the evolutionarily well-conserved first nucleotide-binding fold including the two Walker motifs. Alternative splicing may give rise to various CFTR forms of different function and localization.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1992

Complex pattern of the myelo-monocytic differentiation antigens MRP8 and MRP14 during chronic airway inflammation.

One of the characteristics of cystic fibrosis is the presence of the so-called cystic fibrosis antigen in the plasma of patients. The CF-antigen has been shown to consist of the two calcium-binding proteins MRP8 and MRP14. In the present study we investigate first whether elevated plasma titers of MRP8 and MRP14 are linked to the primary defect of CF or are rather a result of chronic airway inflammation; and second, whether the known complexes of these proteins may have in vivo relevance during inflammation. By employing the ELISA technique we measured MRP8 and MRP14 levels in the plasma of patients suffering from CF or nonspecific chronic bronchitis (CB) and of healthy controls, in sputum of CF and CB patients, and in saliva of CF patients and healthy controls, respectively. We found elevated plasma concentrations of both proteins in CF and CB patients compared to healthy controls. Levels correlated significantly with systemic and local signs of disease activity (i.e. c-reactive protein (CRP), daily sputum production). MRP8 and MRP14 both were found in high amounts at similar concentrations in sputum of CF and CB patients and, to a lesser extent, in saliva of CF patients and healthy donors. After covalent cross-linking at least three different complexes composed of MRP8 and MRP14 with approximate molecular weights of about 25, 35 and 48 kDa were detected in all samples. From this we conclude that the elevated plasma levels of MRP8 and MRP14 in CF and CB are the result of inflammatory processes. Further, possible biological functions of these proteins seem to be associated with complexed forms of MRP8 and MRP14 rather than with individual proteins.

Blotting, Western↗
PubMed1989

Selective expression of an amiloride-inhibitable Na+ conductance from mRNA of respiratory epithelium in Xenopus laevis oocytes.

Poly(A)+RNA was prepared from primary cultures of human nasal polyp epithelia and from native bovine tracheal epithelia. Six to fifty nanograms mRNA were injected into prophase-arrested immature Xenopus laevis oocytes. One to four days later the oocytes were probed with electrophysiological techniques for induction of novel ion conductances. Oocytes injected with mRNA had lower membrane potentials (Vm) and resistances (Rm) than controls. By use of step changes in extracellular Na+ concentration and applying amiloride, a Na+ conductance could be identified in mRNA-injected oocytes, which was inhibited by submicromolar concentrations of amiloride with the same kinetics (Ki = 1.3 X 10(-7) mol/l) as in the original tissue. After complete inhibition of this conductance by 10(-5) mol/l amiloride, Vm and Rm approached the respective values of controls. The data indicate that oocytes express functional epithelial Na+ channels but apparently no other epithelial ion conductances from injected mRNA of respiratory epithelium.

Amiloride↗
PubMed1986

Crystallization of the gastric H,K-ATPase.

Crystalline arrays of the gastric H,K-ATPase were obtained in membrane preparations from hog and rabbit gastric mucosa. The lattice was formed rapidly in a medium containing K+, vanadate, Mg2+, and dimethyl sulfoxide at pH 6.0-6.9 in imidazole buffer from 4 to 22 degrees C. The crystal lattice exhibited P2 symmetry, and the unit cell dimension (a = 5.6, b = 11, and c = 10 nm) could accommodate 2 polypeptides of mass 116-129 kDa. In addition, the isolated preparation contained previously undescribed long cylindrical structures 16 nm thick. These structures consisted of a central core 6-7 nm wide from which particles spaced 5.5 nm apart protruded symmetrically.

Adenosine Triphosphatases↗