Biomedical subjects
Publications and source records attributed to M Schwarz.
Liposuction is an easy to learn technique that suits as an outpatient procedure. Tight budgets have led to a widespread and sometimes uncritical use. The possible mistakes and dangers in patient selection, informed consent, pre- and post-OP management are discussed. Other points are the monitoring and the proper use of compression bandages.
To date, the available therapies for the treatment of HIV infection are targeted against proteins encoded by the virus itself. Thus, combination drug therapies for HIV with reverse transciptase and protease inhibitors have resulted in spectacular reductions of viraemia, often leading to a remarkable improvement in symptoms and recovery from disease in infected people. There is still however, a great need for improved therapies since many patients are unable to take these drugs, either for reasons of intolerance, strain resistance, complexity of regimen or prohibitive cost. Multiple therapies aimed at different events in the HIV life cycle will ensure switching of treatments to combat resistant viruses, and also allow treatment flexibility if patients are unable to tolerate particular therapies. One event that could provide a key to reducing or even eliminating viral infection would be to prevent the virus from entering the host cell. Intense efforts are now underway to produce drugs that target chemokine receptors, one of the essential components for HIV cell entry. HIV needs two receptors on the host cell surface for efficient attachment and infection. The first is CD4 and the second, identified in 1996, is a member of the family of chemokine receptors, members of the G-protein coupled 7TM superfamily, which are involved in the trafficking of leukocytes in immune surveillance and inflammation. Many small, orally bioavailable molecules that block various 7TM receptors are used to treat a panoply of diseases including ulcers, allergies, migraines, and schizophrenia. These molecules are the cornerstone of the pharmaceutical industry's contribution to the fight against so many diseases. Small molecule inhibitors of the HIV-coreceptors are now entering the first stages of clinical trials as new therapeutics for the fight against AIDS.
Members of the nuclear receptor superfamily of ligand-regulated transcription factors play critical roles in multiple aspects of development, cellular differentiation and homeostasis. The ligand-dependent transcriptional effects of nuclear receptors are, in part, mediated by interactions with a group of proteins collectively known as transcriptional coactivators. Receptor agonists promote coactivator binding and receptor antagonists suppress coactivator binding. Recently, biochemical assays that detect ligand-binding based on coactivator recruitment have been developed for several 'orphan' nuclear receptors, i.e., receptors for which no bona fide endogenous ligands are known. We review how these assays have been used to identify naturally occurring and synthetic ligands for the liver X receptor, farnesoid X receptor and estrogen receptor-related receptor subfamilies of orphans, the use of these ligands in the discovery of novel biological signaling pathways and the potential clinical implications of these findings.
Connexin32 (Cx32) is the major gap junction forming protein in liver. We have recently shown that hepatocarcinogenesis is strongly enhanced in mice deficient in Cx32, demonstrating that lack of functional Cx32 accelerates liver tumorigenesis. Many tumor-promoting agents, including phenobarbital, block gap junctional intercellular communication in vitro, and it has been suggested that this effect is relevant for clonal expansion of neoplastic cells in vivo. We have now tested this hypothesis by analyzing the potency of phenobarbital as a liver tumor promoter in male Cx32-wild-type (Cx32(Y/+)) and Cx32-null (Cx32(Y/-)) mice. Preneoplastic and neoplastic liver lesions were induced in 6-week-old male mice by a single injection of 90 microg/g body weight of N-nitrosodiethylamine, and groups of mice were subsequently kept on phenobarbital-containing (0.05%) or control diet for 39 weeks. Frozen liver sections were prepared, and (pre)neoplastic lesions were identified by their deficiency in glucose-6-phosphatase staining. In addition, the number and size of macroscopically visible tumors were monitored. Phenobarbital led to a approximately 5-fold increase in the volume fraction occupied by glucose-6-phosphatase-deficient liver lesions in Cx32(Y/+) mice, whereas there was no such increase in Cx32(Y/-) mice. Even more pronounced differences were observed with respect to tumor response. Whereas phenobarbital clearly promoted the occurrence of numerous large hepatomas in Cx32(Y/+) mice, no such effect was seen in Cx32(Y/-) mice. These results demonstrate, for the first time, that functional Cx32 protein is required for tumor promotion by phenobarbital.
We use a stochastic model describing initiation and clonal growth of altered cells to analyze data from an initiation-promotion hepatocarcinogenesis experiment in female Wistar rats. Starting at 7 weeks of age, the animals were treated for 10 days with the initiating agent diethylnitrosamine (DEN, 10 mg/kg body wt per day). After a 10-week resting period, the animals were treated either with corn oil or with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) via biweekly sc injections of 1.4 microg/kg body wt of TCDD dissolved in corn oil. Groups of four or five animals were euthanized 3, 17, 31, 73, and 115 days after start of TCDD/corn oil treatment. The data analyzed consist of the number and sizes of GST-P-positive focal transections at various time points. By fitting the model to the data, we estimate the rates of initiation, cell division, and cell death during different time periods of the experiment. The model estimates of cell kinetic parameters are consistent with directly made experimental observations of cell division and cell death. The model predicts that DEN-induced initiation of GST-P-positive cells is highly protracted in controls and TCDD-treated animals alike. We also find that TCDD interferes with the normal rate at which cells with (DEN-inflicted) DNA damage are converted into cells expressing the GST-P-positive phenotype, suggesting a TCDD-mediated "acceleration" of the appearance of de novo GST-P-positive initiated cells from damaged precursor cells. Furthermore, the model predicts a significant reduction in the rate of apoptosis within the first 4 to 5 weeks of TCDD treatment, and after 10 weeks of TCDD treatment, but not in between.
We used functional magnetic resonance imaging to disentangle the functional anatomy of brain systems involved in the processing of auditory word form and meaning. Three monitoring tasks on auditory stimuli, aimed at phonetic, lexical and semantic processing, were used. We found no lateralization of temporal lobe activations, when word processing was contrasted versus the complex phonetic task. Bilateral middle temporal activations (Brodmann Area [BA] 21) were attributed to processing of word-form. Areas specific to semantic processing were restricted to the left hemisphere: the posterior middle frontal (BA 9) and posterior parietal (BA 7/40) cortex, as well as an inferior temporal area (BA 20/21). Our data suggest, that left hemispheric dominance for auditory word comprehension occurred at the level of semantic processing.
We cloned two beta subunits of large-conductance calcium-activated potassium (BK) channels, hKCNMB3 (BKbeta1) and hKCNMB4 (BKbeta4). Profiling mRNA expression showed that hKCNMB3 expression is enriched in testis and hKCNMB4 expression is very prominent in brain. We coexpressed BK channel alpha (BKalpha) and BKbeta4 subunits in vitro in CHO cells. We compared BKalpha/beta4 mediated currents with those of smooth muscle BKalpha/beta1 channels. BKbeta4 slowed activation kinetics more significantly, led to a steeper apparent calcium sensitivity, and shifted the voltage range of BK current activation to more negative potentials than BKbeta1. BKalpha/beta4 channels were not blocked by 100 nM charybdotoxin or iberiotoxin, and were activated by 17beta-estradiol.
A number of agonists of the aryl hydrocarbon or dioxin receptor (AhR) are potent tumor promoters in rodent liver. The prototype compound is 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Tumor promotion by TCDD is likely to be AhR-mediated. Tumor promoters may affect the rate of division, terminal differentiation or death (apoptosis) of tumor precursor cells. The present paper reviews some of the effects of TCDD on liver cell homeostasis that have been observed under diverse experimental settings and discusses some of the possible underlying mechanisms.
To form a diffusible interface large enough to conduct respiratory gas exchange with the circulation, the lung endoderm undergoes extensive branching morphogenesis and alveolization, coupled with angiogenesis and vasculogenesis. It is becoming clear that many of the key factors determining the process of branching morphogenesis, particularly of the respiratory organs, are highly conserved through evolution. Synthesis of information from null mutations in Drosophila and mouse indicates that members of the sonic hedgehog/patched/smoothened/Gli/FGF/FGFR/sprouty pathway are functionally conserved and extremely important in determining respiratory organogenesis through mesenchymal-epithelial inductive signaling, which induces epithelial proliferation, chemotaxis and organ-specific gene expression. Transcriptional factors including Nkx2.1, HNF family forkhead homologues, GATA family zinc finger factors, pou and hox, helix-loop-helix (HLH) factors, Id factors, glucocorticoid and retinoic acid receptors mediate and integrate the developmental genetic instruction of lung morphogenesis and cell lineage determination. Signaling by the IGF, EGF and TGF-beta/BMP pathways, extracellular matrix components and integrin signaling pathways also directs lung morphogenesis as well as proximo-distal lung epithelial cell lineage differentiation. Soluble factors secreted by lung mesenchyme comprise a 'compleat' inducer of lung morphogenesis. In general, peptide growth factors signaling through cognate receptors with tyrosine kinase intracellular signaling domains such as FGFR, EGFR, IGFR, PDGFR and c-met stimulate lung morphogenesis. On the other hand, cognate receptors with serine/threonine kinase intracellular signaling domains, such as the TGF-beta receptor family are inhibitory, although BMP4 and BMPR also play key inductive roles. Pulmonary neuroendocrine cells differentiate earliest in gestation from among multipotential lung epithelial cells. MASH1 null mutant mice do not develop PNE cells. Proximal and distal airway epithelial phenotypes differentiate under distinct transcriptional control mechanisms. It is becoming clear that angiogenesis and vasculogenesis of the pulmonary circulation and capillary network are closely linked with and may be necessary for lung epithelial morphogenesis. Like epithelial morphogenesis, pulmonary vascularization is subject to a fine balance between positive and negative factors. Angiogenic and vasculogenic factors include VEGF, which signals through cognate receptors flk and flt, while novel anti-angiogenic factors include EMAP II.
The LQT1 locus (KCNQ1) has been correlated with the most common form of inherited long QT (LQT) syndrome. LQT patients suffer from syncopal episodes and high risk of sudden death. The KCNQ1 gene encodes KvLQT1 alpha-subunits, which together with auxiliary IsK (KCNE1, minK) subunits form IK(s) K(+) channels. Mutant KvLQT1 subunits may be associated either with an autosomal dominant form of inherited LQT, Romano-Ward syndrome, or an autosomal recessive form, Jervell and Lange-Nielsen syndrome (JLNS). We have identified a small domain between residues 589 and 620 in the KvLQT1 C-terminus, which may function as an assembly domain for KvLQT1 subunits. KvLQT1 C-termini do not assemble and KvLQT1 subunits do not express functional K(+) channels without this domain. We showed that a JLN deletion-insertion mutation at KvLQT1 residue 544 eliminates important parts of the C-terminal assembly domain. Therefore, JLN mutants may be defective in KvLQT1 subunit assembly. The results provide a molecular basis for the clinical observation that heterozygous JLN carriers show slight cardiac dysfunctions and that the severe JLNS phenotype is characterized by the absence of KvLQT1 channel.
BACKGROUND: Bacterial translocation through the gastrointestinal tract is the crucial step in the pathogenesis of intraabdominal infections. We assessed whether aggregation substance (AS), a bacterial adhesin and virulence factor of Enterococcus faecalis, promotes bacterial translocation and colonic mucosal invasion in an ex vivo experiment. METHODS: Colonic mucosa of male Wistar rats was placed in a modified Ussing system. The mucosal side of the chamber was filled with a suspension of E. faecalis OG1X:pAM721 (AS-positive) or E. faecalis OG1X (AS-negative). The serosal side was filled with sterile Dulbecco's modified Eagle's medium. For assessment of colonic mucosal invasion the mucosal side was incubated for 2.5 h with a suspension of AS-positive or AS-negative enterococci. After being washed, a solution of gentamicin and penicillin G in tissue culture medium was added on both sides in order to kill extracellular bacteria. Subsequently, the mucosa was removed from the system, washed, lysed with Triton X-100, and homogenized. Viable intramural bacteria were quantified by plating serial dilutions of the homogenate on Todd-Hewitt broth agar plates. To quantify bacterial translocation samples which were taken at various time points from the serosal side were plated on Todd-Hewitt broth agar plates and colony forming units (CFU) were determined. RESULTS: Invasion of the AS-positive E. faecalis strain OG1X:pAM721 into the colonic mucosa was significantly higher than invasion rates of the AS-negative strain OG1X (2.88 log(10) CFU/ml vs 1.73 log(10) CFU/ml; P = 0.02). However, none of the tested strains was found to translocate from the mucosal to the serosal side within the incubation time of 4 h. CONCLUSIONS: The aggregation substance promotes invasion of E. faecalis into colonic mucosa.
Brainstem dysfunction was evaluated in 67 patients with myelomeningocele and Chiari II malformation using brainstem auditory evoked potentials (BAEP), blink reflex (BR) and masseter reflex (MR). Signs and symptoms related to Chiari II malformation were observed in 18 patients while 49 patients had normal brainstem findings. BAEP and BR showed a higher sensitivity of brainstem involvement than MR (BAEP=1.0, BR=0.83, MR=0.50). BR, and in particular, MR were of higher accuracy (BR=0.52, MR=0.72) than BAEP (0.39) in separating patients with brainstem signs and symptoms related to Chiari II malformation. We feel that this is due to anatomic and physiologic peculiarities of the brainstem structures mediating BR and MR. Our results suggest that brainstem reflexes can support the decision of further treatment.
These recommendations for quality improvement of cystic fibrosis genetic diagnostic testing provide general guidelines for the molecular genetic testing of cystic fibrosis in patients/individuals. General strategies for testing as well as guidelines for laboratory procedures, internal and external quality assurance, and for reporting the results, including the requirements of minimal services in mutation testing, the nomenclature for describing mutations, procedures to control false-positive amplification reactions and to validate tests, and guidelines to implement a quality system in a molecular diagnostic laboratory are reviewed.
Mice deficient for connexin32 (Cx32), the major gap junction forming protein in liver, are highly susceptible to hepatocarcinogenesis. Because the Cx32 gene is located on the X-chromosome, heterozygous females show mosaicism with respect to Cx32 expression; this enables their use in studying the effect of Cx32-deficiency in a mixed Cx32-plus/Cx32-minus environment in vivo. Female C3H/He mice (Cx32(+/+)) were crossed with Cx32-deficient C57BL/129Sv males (Cx32(Y/-)) to yield F1 females heterozygous with respect to Cx32 (Cx32(+/-)). Patches of hepatocytes were observed in normal liver that either expressed Cx32 or failed to express the protein. The mean fraction of Cx32-negative tissue in liver was about 60% and did not change significantly with age of mice. Neoplastic liver lesions, induced in weanling mice, were identified in serial liver sections by their deficiency in glucose-6-phosphatase staining. Parallel sections were used for immunohistochemical demonstration of Cx32 protein. Smaller lesions were either homogenously Cx32-negative or showed unchanged to slightly elevated levels of Cx32 protein. There were no major differences in number and size distribution between lesions of these 2 phenotypes. In addition, larger lesions were mostly Cx32-negative but often contained embedded patches of Cx32-positive cells. Staining for the proliferation-associated nuclear antigen Ki-67 did not reveal significant differences between Cx32-negative and Cx32-positive hepatocytes in Cx32-mosaic tumors. This suggests that expression of Cx32 within a subpopulation of tumor cells does not negatively regulate their growth nor does it seem to affect the proliferation of their directly neighboring Cx32-negative counterparts.
Endoscopic treatment of chronic pancreatitis using pancreatic duct stents was first described 15 years ago. Considering our own experience and the data of the literature we describe indications, contraindications, risks and limitations of the procedure and on the other hand its therapeutic effects. According to the actual experience an indication for pancreatic duct stenting can be seen in patients with a solitary prepapillary stenosis without stenosis of side branches or as success control for a planned surgical intervention. Contraindications are suspected malignancy, multiple pancreatic duct stenosis in the main duct or stenosis in small ducts and chronic calcifying pancreatitis with pancreatic duct stones. From 6/92 until 5/97 189 patients were operated for chronic pancreatitis in the Ulm University Hospital. Of these patients 35 (18.7%) were unsuccessfully treated preoperatively in other hospitals by pancreatic duct stent. Because of frequent complications like stent dislocation and stent occlusion repeated ERCPs (4.5/patient) and stent exchanges (3.7/patient) were performed. A therapeutical long-term benefit of pancreatic duct stenting is questionable, a definitive therapy can only be achieved in a small group of patients. However stent-induced changes of the pancreatic duct similar to chronic pancreatitis can be observed in up to 80% of all patients. Long-term observations of the reversibility of these stent-induced changes are missing, persisting chronic pancreatitis in the stented region is reported in animal models and in humans. The rates in the literature for stent dislocation and stent occlusion rate are 10-18% and 39-100% respectively. Induction of acute pancreatitis (up to 10%), duodenal reflux into the pancreatic duct, and bacterial infection with abscess formation are further severe and frequent complications of pancreatic duct stenting (1, 2). Lethal courses are reported (3, 4). Endoscopic pancreatic duct stenting in chronic pancreatitis at present is not indicated because of low success rate and a substantial risk of complications.
BACKGROUND: Contradictory reports exist concerning the role of the angiotensin II type 1 receptor A1166C polymorphism as a coronary risk factor. Moreover, it is unknown whether the A1166C polymorphism is associated with thrombotic complications after coronary catheter interventions. METHODS: We investigated the role of the A1166C polymorphism as a risk factor in 1000 patients with coronary artery disease (CAD) and in 1000 age- and sex-matched controls. A total of 649 patients receiving interventions (270 coronary angioplasty, 102 atherectomy, and 277 stenting) were investigated for a 30-day composite end point including target vessel revascularization, myocardial infarction, or death. RESULTS: The composite end point was reached by 42 patients (6.5%) without evidence that the C allele was associated with excess procedural risk (odds ratio 0.93; 95% confidence interval 0.79-1.75; P =.82). Further analyses by device failed to show linkage with adverse events complicating coronary angioplasty, atherectomy, and stenting. Moreover, in the entire CAD group (n = 1000), the polymorphism even showed a trend to underrepresentation (odds ratio 0.83; 95% confidence interval 0.69-1. 004, P =.054). CONCLUSIONS: These results indicate that the A1166C polymorphism neither represents a risk factor for adverse events complicating coronary interventions nor seems to have significant impact on further long-term processes such as development and severity of CAD.
BACKGROUND: Infectious complications in severe pancreatitis are the main factors determining clinical course and outcome. The taurocholate model for acute necrotizing pancreatitis was evaluated for frequency and time course of pancreatic and extrapancreatic bacterial infection. METHODS: Sixty-five male Wistar rats were divided into 5 groups of 13 animals each. Specimens for bacteriologic examination were taken, and pancreatitis was induced by intraductal infusion of 3% taurocholate under sterile conditions. Animals were killed 8, 16, 24, or 32 hours thereafter, and bacteriologic examination was performed. A control group of animals with intraductal infusion of 0.9% saline solution were killed after 32 hours. RESULTS: There was no significant pancreatic infection in the control group and in the 8-hour group (1 of 13 rats). Sixteen and 24 hours after induction of pancreatitis, infection and inflammation of the pancreas were found in 77% (10 of 13 rats), and after 32 hours pancreatic infection occurred in 69% (9 of 13 rats). Extrapancreatic bacterial infection after 16 hours occurred in the liver (62%), spleen (62%), and mesenteric lymph nodes (46%). Bacteria infecting the pancreas reflected the bacterial spectrum of the large bowel and terminal ileum before induction of pancreatitis (Escherichia coli [77%], Proteus [43%], Enterococcus [37%], and Staphylococcus [23%]). CONCLUSIONS: Pancreatic infection is an early and frequent finding in the taurocholate model of acute necrotizing pancreatitis. Infection occurs between 8 and 16 hours after induction of pancreatitis. The source of infecting bacteria seems to be the large bowel or the terminal ileum. We present a useful model of severe pancreatitis in which to study bacterial translocation, the further route of spread, and therapeutic approaches.
Liver tumors were induced in male C3H mice by a single injection of N-nitrosodiethylamine and characterized with respect to the presence of base substitutions in the hot-spot position at codon 61 of the Ha-ras proto-oncogene. An increase in Ha-ras mutation prevalence was found with time after induction of tumors, suggesting that the activated ras gene provides a selective growth advantage. However, no significant differences in 5-bromodeoxyuridine labeling indices were evident between ras mutated and ras wild-type tumors, demonstrating that cell division rates in the two tumor populations were very similar. Apoptotic indices were determined by counting eosinophilic apoptotic bodies. The frequency of occurrence of apoptotic bodies was found to be approximately five times lower in tumors with Ha-ras mutations when compared with tumors not showing the mutation. This demonstrates that the activated p21(Ras) protein has anti-apoptotic activity in transformed mouse hepatocytes in vivo and suggests that the preferential outgrowth of Ha-ras-mutated hepatoma cells is mediated by suppression of apoptosis rather than by stimulation of cell division.