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U Müller

Publications and source records attributed to U Müller.

At least 145 records · Page 8Linked to original sources
PubMed1999

PGL3, a third, not maternally imprinted locus in autosomal dominant paraganglioma.

Paragangliomas (glomus tumors) are slowly growing, mostly benign tumors of the parasympathetic ganglia which most frequently occur in the head and neck region. Between 10% and 50% of cases are familial and follow an autosomal dominant mode of inheritance. The trait is maternally imprinted and exclusively transmitted through the paternal line. To date, two loci have been implicated in this disorder: one at 11q23 (PGL1), the other one at 11q13 (PGL2). We have analyzed a large German family with hereditary paraganglioma, but no evidence of maternal imprinting. By linkage analysis with markers flanking both PGL1 and PGL2, we demonstrate that the trait does not segregate with either of the loci at 11q. Our findings show that a third locus, PGL3, can be involved in hereditary paraganglioma.

Aged↗
PubMed1999

Ten years of gene targeting: targeted mouse mutants, from vector design to phenotype analysis.

Gene targeting, defined as the introduction of site-specific modifications into the genome by homologous recombination, has revolutionarized the field of mouse genetics and allowed the analysis of diverse aspects of gene function in vivo. It is now possible to engineer specific genetic alterations ranging from subtle mutations to chromosomal rearrangements and more recently, even tissue-specific inducible gene targeting with temporo-spatial control has become feasible. This review tries to recapitulate what we have learned in this extremely rapidly expanding field during the past decade. Diverse aspects of the technique will be discussed starting from basic construct design to the analysis of complex phenotypes, including recent advances on inducible expression system. Many examples from different areas of biomedical research are given to illustrate the purpose and limitations of the employed experimental approaches.

Animals↗
PubMed1999

p45SKP2 promotes p27Kip1 degradation and induces S phase in quiescent cells.

The F-box protein p45SKP2 is the substrate-targeting subunit of the ubiquitin-protein ligase SCFSKP2 and is frequently overexpressed in transformed cells. Here we report that expression of p45SKP2 in untransformed fibroblasts activates DNA synthesis in cells that would otherwise growth-arrest. Expression of p45SKP2 in quiescent fibroblasts promotes p27Kip1 degradation, allows the generation of cyclin-A-dependent kinase activity and induces S phase. Coexpression of a degradation-resistant p27Kip1 mutant suppresses p45SKP2-induced cyclin-A-kinase activation and S-phase entry. We propose that p45SKP2 is important in the progression from quiescence to S phase and that the ability of p45SKP2 to promote p27Kip1 degradation is a key aspect of its S-phase-inducing function. In transformed cells, p45SKP2 may contribute to deregulated initiation of DNA replication by interfering with p27Kip1 function.

Animals↗
PubMed1999

Alpha8 integrin in glomerular mesangial cells and in experimental glomerulonephritis.

BACKGROUND: Mesangial cell (MC) proliferation and extracellular matrix accumulation are typical responses of renal glomeruli to injury. Extracellular matrix components are known to affect MC behavior, which is mediated primarily via integrin receptors of the beta1 family. In addition to alpha1, alpha3, alpha5, and alpha6 chains of beta1 integrins, recent studies have shown the alpha8 chain to be expressed in glomeruli and renal vasculature. alpha8beta1 can serve as a receptor for fibronectin, which is abundant in the mesangium. We investigated the glomerular expression pattern of the alpha8 chain in renal tissues of mouse, rat, and humans as well as in cultured MCs. In addition, the regulation of alpha8 expression in MCs was studied in culture and in nephritic rats. METHODS: The expression of alpha8 protein in kidney tissue and cultured MCs was investigated by immunohistochemistry, immunocytochemistry, and Western blotting. The effects of TGF-beta1 on alpha8 mRNA levels in MCs were studied by Northern blot analysis. In addition, time course studies of glomerular abundance and localization of alpha8 were performed in rats with mesangioproliferative anti-Thy1.1 nephritis. RESULTS: In tissue sections of normal human, rat, and mouse kidney, we found strong immunohistochemical staining for alpha8 in the mesangium and in the media of renal arterioles. Double staining for alpha8 and Thy1.1, a surface antigen of rat MCs, showed alpha8 to be specifically expressed in MCs but not in glomerular endothelial and epithelial cells. In anti-Thy1.1 nephritis of rats, the glomerular abundance of alpha8 protein was reduced in the early mesangiolytic phase but was increased greatly with subsequent MC proliferation, peaking at day 6 of disease. At later stages of this reversible form of nephritis, the number of MCs and the extent mesangial alpha8 staining declined to control levels. Cell culture experiments revealed that freshly plated MCs organize alpha8 into focal contacts within one hour after attachment to fibronectin and vitronectin substrata, showing colocalization with focal contact proteins vinculin and talin. Stimulation of MCs with transforming growth factor-beta1 led to increases of alpha8 mRNA and protein levels. CONCLUSIONS: These results show that in human, rat, and mouse glomeruli, alpha8 integrin is strongly and exclusively expressed in MCs. Gene expression of alpha8 is regulated in cultured MCs, and alpha8 protein abundance is regulated in vivo and in MC culture. It is currently unclear what functional properties this integrin receptor protein has with regard to MC anchorage to extracellular matrix and modulation of the MC phenotype in normal and diseased glomeruli. However, in view of its abundance in the mesangium, alpha8beta1 integrin could be an important MC receptor of matrix ligands and may play a role in the embryology, physiology, and pathophysiology of the glomerular capillary tuft.

Animals↗
PubMed1999

Paroxetine versus citalopram treatment of pathological crying after brain injury.

Selective serotonin reuptake inhibitors (SSRIs) are the treatment of choice for pathological crying after brain injury, independent of accompanying depression. In a series of 26 consecutive patients with acquired brain damage and episodes of involuntary crying, the efficacy and tolerability of paroxetine and citalopram were compared. The severity of pathological crying or laughing was rated based on clinical interviews with symptom provocation. The first 13 patients were treated with paroxetine and another 13 patients received citalopram in single daily doses of 10 to 40 mg. Rapid onset (within 1-3 days) and highly significant (p < 0.001) improvements of emotionalism were observed after both paroxetine and citalopram. There were no efficacy differences, despite the longer symptom duration in the citalopram group. The only adverse effect after paroxetine was nausea, which was reversible, in two patients, and nausea with vomiting in another two patients, who were switched to citalopram. Citalopram was tolerated without adverse effects.

Adult↗
PubMed1999

Molecular diagnosis of bilateral coronal synostosis.

The authors performed a prospective study evaluating molecular diagnosis in patients with bilateral coronal synostosis. The patients were divided into two groups: (1) those clinically classified as having Apert, Crouzon, or Pfeiffer syndrome and (2) those clinically unclassified and labeled as having brachycephaly. Blood samples were drawn for genomic DNA analysis from 57 patients from 1995 to 1997. Polymerase chain reactions were performed using primers flanking exons in FGFR 1, 2, and 3. Each exon was screened for mutations using single-strand confirmation polymorphism, and mutations were identified by DNA sequencing. Mutations in FGFR2 or FGFR3 were found in all patients (n = 38) assigned a phenotypic (eponymous) diagnosis. All Apert syndrome patients (n = 13) carried one of the two known point mutations in exon 7 of FGFR2 (Ser252Trp and Pro253Arg). Twenty-five patients were diagnosed as having either Crouzon or Pfeiffer syndrome. Five patients with Crouzon syndrome of variable severity had mutations in exon 7 of FGFR2. Fifteen patients (12 with Crouzon, 3 with Pfeiffer) had a mutation in exon 9 of FGFR2, many of which involved loss or gain of a cysteine residue. A wide phenotypic range was observed in patients with identical mutations, including those involving cysteine. Two patients labeled as having Crouzon syndrome had the Pro250Arg mutation in exon 7 of FGFR3. All three patients with the crouzonoid phenotype and acanthosis nigricans had the same mutation in exon 10 of FGFR3 (Ala391Glu). This is a distinct disorder, characterized by jugular foraminal stenosis, Chiari I anomaly, and intracranial venous hypertension. Mutations were found in 14 of 19 clinically unclassifiable patients. Three mutations were in exon 9, and one was in the donor splice site of intron 9 on FGFR2. The most common mutation discovered in this group was Pro250Arg in exon 7 of FGFR3. These patients (n = 10) had either bilateral or unilateral coronal synostosis, minimal midfacial hypoplasia with class I or class II occlusion, and minor brachysyndactyly. No mutations in FGFR 1, 2, or 3 were detected in five patients with nonspecific brachycephaly. In conclusion, a molecular diagnosis was possible in all patients (n = 38) given a phenotypic (eponymous) diagnosis. Different phenotypes observed with identical mutations probably resulted from modulation by their genetic background. A molecular diagnosis was made in 74 percent of the 19 unclassified patients in this series; all mutations were in FGFR2 or FGFR3. Our data and those of other investigators suggest that we should begin integrating molecular diagnosis with phenotypic diagnosis of craniosynostoses in studies of natural history and dysmorphology and in analyses of surgical results.

Child↗
PubMed1999

Crystallization and X-ray diffraction data of a tRNASec acceptor-stem helix.

tRNASec is a UGA suppressor tRNA which co-translationally inserts selenocysteine into proteins. Its eight-base-pair tRNASec acceptor stem, which contains key recognition elements, was synthesized using solid-phase phosphoramidite RNA chemistry. High-resolution X-ray diffraction data were collected using synchrotron radiation under cryogenic cooling conditions. The crystals diffract to a maximal resolution of 1.8 A. X-ray diffraction data were processed to 2.4 A. tRNASec microhelix crystallizes in space group R32, with cell constants a = 47.02, b = 47.02, c = 373.03 A, alpha = beta = 90, gamma = 120 degrees. The crystals contain three RNA molecules per asymmetric unit.

Crystallization↗
PubMed1999

Drug-induced linear IgA bullous dermatosis associated with ceftriaxone- and metronidazole-specific T cells.

BACKGROUND: Previous reports indicate that various drugs may induce linear IgA bullous dermatosis (LABD). The role of T cells and T-cell-derived cytokines in the pathomechanism of such skin lesions, however, has remained unclear. OBJECTIVE: To describe a case of LABD induced by ceftriaxone and metronidazole in an 80-year-old female suffering from cholelithiasis with concomitant cholecystitis and provide evidence that drug-specific T cells and their cytokines may contribute to the development of LABD lesions. METHODS: We performed flow cytometry analysis of peripheral blood T cells during LABD, epicutaneous testing (scratch-patch) and lymphocyte proliferation analysis (LTT) with the suspected drugs, routine histological and immunohistochemical examination of the acute skin lesions during LABD as well as of the positive epicutaneous test reactions and measurement of cytokines (IL-4, IL-5, IL-10, TNF-alpha, IFN-gamma) in the supernatant of the LTT cultures. RESULTS: An increased number mainly of activated CD8+ cells was detected in the peripheral blood during LABD. T cell sensitization to ceftriaxone and metronidazole was confirmed by epicutaneous testing and LTT, indicating that these methods may be useful in identifying the causative drugs. Enhanced cytokine levels, particularly of IL-5, were found in the supernatant of the LTT stimulated with ceftriaxone and metronidazole. Furthermore, in situ expression of IL-5 was confirmed in the patient's skin lesions by immunohistochemistry. CONCLUSION: Our findings suggest that in addition to IgA antibodies drug-specific T cells and their subsequent release of cytokines may play an important role in the pathogenesis of drug-induced LABD.

Aged↗
PubMed1999

Nocturnal hormone secretion and the sleep EEG in patients several months after traumatic brain injury.

After severe traumatic brain injury (TBI), sleep disturbances and changes in hormone secretion are frequently observed. Similarly, in depression, abnormalities of sleep and neuroendocrine regulation are common. To test the hypothesis that the changes in brain-injured patients several months after injury are similar to those seen in patients with depression, the authors investigated simultaneously the sleep EEG and nocturnal hormone secretion in 13 young male nondepressed patients after TBI and 13 age-matched control subjects. The resulting data show a pattern of sleep-endocrine changes in patients after TBI, which has some similarities to that of patients with remitted depression.

Adult↗
PubMed1999

Cell adhesion molecules and extracellular-matrix constituents in kidney development and disease.

Functional analyses of cell-matrix interactions during kidney organogenesis have provided compelling evidence that extracellular-matrix glycoproteins and their receptors play instructive roles during kidney development. Two concepts are worthy of emphasis. First, matrix molecules appear to regulate signal transduction pathways, either by activating cell-surface receptors such as integrins directly or by modulating the activity of signaling molecules such as WNTs. Second, basement membranes are highly organized structures and have distinct molecular compositions, which are optimized for their diverse functions. The importance of these findings is highlighted by the fact that mutations affecting basement-membrane components lead to inherited forms of kidney disease.

Animals↗
PubMed1999

[Gastrointestinal complications of adult patients with cystic fibrosis].

Cystic fibrosis (CF) is the most common autosomal recessive disease in the Caucasian population. The primary cellular defect, the reduced expression of the cystic fibrosis transmembrane conductance regulator (CFTR), leading to a chloride secretory defect, is present in all epithelial cells of endodermal and mesodermal origin and has been described in sweat glands, the airway epithelium and the small intestine, the colon and rectum, including the pancreas. In the upper GI-tract the most troublesome complaints and symptoms originating from the esophagus are peptic esophagitis or esophageal varices. In the small intestinal wall, the clinical expression of CF largely depends on the decreased secretion of fluid and chloride ions and the sticky mucous covering the enterocytes. Although CFTR expression in the colon is lower, the large intestine may be the site of several serious complications such as rectal prolapse, distal intestinal obstruction (DIOS), and intussusception. In recent years an increase in colonic strictures after the use of high-dose pancreatic enzymes, has been increasingly reported. CF has also been reported to be increasingly associated with a number of hepatic and/or biliary abnormalities, of which chronic cholestatic liver disease is by far the most relevant. Plugging of intrahepatic bile ducts with inspissated secretions is thought to play a major role in the pathogenesis. It has been estimated that about 15% of cystic fibrosis patients reveal serum liver enzyme abnormalities, but prevalence of liver involvement is likely to be higher. Oral bile acid therapy is promising, but its long-term benefits in terms of survival and prevention of major complications by liver cirrhosis remain to be established. Pancreatic dysfunction in cystic fibrosis (CF) is characterized by an insufficient pancreatic exocrine function. However, 10-15% of CF patients have pancreatic sufficiency and this status is genetically determined by one or two "mild" mutations in the CFTR.

Adult↗
PubMed1998

Moderate dose escalation for advanced stage Hodgkin's disease using the bleomycin, etoposide, adriamycin, cyclophosphamide, vincristine, procarbazine, and prednisone scheme and adjuvant radiotherapy: a study of the German Hodgkin's Lymphoma Study Group.

The BEACOPP (bleomycin, etoposide, adriamycin, cyclophosphamide, vincristine, procarbazine, and prednisone) regimen, a rearranged and accelerated version of the standard COPP/adriamycin, bleomycin, vinblastine, and dacarbazine (ABVD) chemotherapy, has been shown to be effective and safe in a previous pilot study for advanced stage Hodgkin's disease (HD). The present study aimed to determine a maximum practicable dose of three drugs, ie, etoposide, adriamycin, and cyclophosphamide, for which acute toxicities were acceptable and to assess the feasibility of the escalated scheme. Sixty untreated patients with advanced stage HD were enrolled in this study. Radiotherapy was given in 44 patients (73%) after chemotherapy to initial bulk lesions and residual disease. Granulocyte-colony stimulating factor (G-CSF) was given from day 8 to prevent prolonged neutrocytopenia and severe infections. The intended doses of adriamycin, etoposide, and cyclophosphamide in the BEACOPP schedule could be substantially escalated: adriamycin from 25 to 35, cyclophosphamide from 650 to 1,200, and etoposide from 100 to 200 mg/m2. The major toxicities were leukocytopenia and thrombocytopenia with considerable heterogeneity between individual patients. Of 60 patients, 56 (93%) achieved a complete remission (CR). At a median observation of 32 months, the rates of survival and freedom from treatment failure (FFTF) were estimated to be 91% (95% confidence interval 83% to 99%) and 90% (82% to 98%). These results show that a moderate dose escalation of adriamycin, cyclophosphamide, and etoposide of the baseline BEACOPP regimen is feasible. The escalated BEACOPP regimen shows very encouraging results in advanced stage HD and is now being compared in a randomized phase III study with BEACOPP at baseline dose level.

Adolescent↗
PubMed1998

Structure of the gene encoding the ubiquitin-conjugating enzyme Ubcm4, characterization of its promoter, and chromosomal location.

Ubiquitin-conjugating enzymes (E2 or Ubc) play a key role in the post-translational modification of proteins by ubiquitylation. They are encoded by a large family of genes that are closely related to each other. In this paper we present the first complete structural analysis, including the promoter and the chromosomal location, of a member of this family, the mouse Ubcm4 gene. At the genomic level the Ubcm4 gene spans approx. 50kb and is composed of four exons. Only about 1% of the total gene codes for amino acids. The four different Ubcm4 specific RNAs encode the same protein and differ only in the length of the 3' untranslated region. The polyadenylation signals used by the four different RNAs are all within the 3' terminal exon. At the 5' end of the gene, multiple transcriptional start sites were mapped within a region of 25bp. The region proximal to the initiation sites does not contain a TATA box and is not GC-rich. Transient chloramphenicol acetyltransferase assays, however, showed that this region can promote the expression of a reporter gene and that 15bp upstream of the first initiation site were sufficient for basal expression. The Ubcm4 gene was mapped by interspecific backcross analysis to the proximal region of mouse chromosome 16.

Amino Acid Sequence↗
PubMed1998

[Implantable event recorder: a new aid for the diagnosis of arrhythmogenic syncope].

HISTORY AND CLINICAL FINDINGS: A 52-year-old woman had for 31 years been experiencing occasional episodes of dizziness and syncope, as well as sudden attacks of "shaking" in the chest associated with cramp-like pain, nausea and weak spells, each lasting for up to 45 min. She had since childhood been suffering from atopy, with bronchial asthma and polyvalent allergies. On examination, which was otherwise unremarkable, her blood pressure was 140/100 mm Hg with a sinus tachycardia of 110/min. She was admitted for implantation of an event recorder to establish the etiology of the described symptoms. INVESTIGATIONS: The results of routine laboratory tests, including those of thyroid function, were within normal limits. The ECG showed sinus rhythm and minor left precordinal abnormalities of repolarization. The echocardiogram was normal and coronary angiography excluded coronary heart disease. TREATMENT AND COURSE: 3 weeks after ambulatory implantation of an event recorder (Reveal, Medtronic) she again had an attack. The recorded ECG indicated a supraventricular tachycardia (190/min), preceded by an atrial extrasystole, lasting 3 min 14 s. She was treated with digitalis and verapamil, her asthma contraindicating solatol. She had refused further invasive diagnostic measures. The appearance of an allergic rash required a change of drugs to propafenon. But as this, too, was poorly tolerated, electrophysiological testing was undertaken. It revealed an AV nodal reentry tachycardia which was treated with local ablation: supraventricular extrasystoles continued to occur frequently, but there were no further episodes of reentry tachycardia. CONCLUSION: In patients with recurrent syncopes, but otherwise unremarkable clinical findings, an implantable event recorder may provide important diagnostic information, especially relating to a possible arrhythmogenic cause.

Anti-Arrhythmia Agents↗
PubMed1998

Positive selection through a motif in the alphabeta T cell receptor.

The two lineages of T cells, alphabeta and gammadelta, differ in their developmental requirements: only alphabeta T cells require major histocompatibility complex recognition, a process known as positive selection. The alphabeta T cell receptor (TCR), but not its gammadelta counterpart, contains a motif within the alpha-chain connecting peptide domain (alpha-CPM) that has been conserved over the last 500 million years. In transgenic mice expressing an alphabeta TCR lacking the alpha-CPM, thymocytes were blocked in positive selection but could undergo negative selection. Thus, the alpha-CPM seems to participate in the generation of signals required for positive selection.

Amino Acid Sequence↗