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R Baumann

Publications and source records attributed to R Baumann.

At least 73 records · Page 4Linked to original sources
PubMed1996

Specific immunohistochemical detection of cardiac/fetal alpha-actin in human cardiomyocytes and regenerating skeletal muscle cells.

We describe three murine monoclonal antibodies (mAbs) raised against a synthetic decapeptide representing the aminoterminal sequence of the cardiac/ fetal isoform of sarcomeric alpha-actin. When used for immunoblotting or histological immunolocalization, these mAbs distinguish cardiac/fetal alpha-actin from skeletal muscle alpha-actin, and also from all other actin isoforms. We show, by immunofluorescence and immunoperoxidase microscopy of tissue sections, that cardiac/fetal alpha-actin can be localized not only in cardiomyocytes but also in skeletal muscles and their satellite cells during regeneration. These mAbs are potentially valuable in developmental biology, for the characterization of tissue and cultured myogenic cells, in pathology, and for serodiagnosis.

Actins↗
PubMed1996

Increased production of tumour necrosis factor-alpha interleukin-1 beta, and interleukin-6 by morphologically normal intestinal biopsies from patients with Crohn's disease.

BACKGROUND: Increasing evidence points to a important role for inflammatory cytokines for the pathogenesis of Crohn's disease. AIM: To compare the secretion rate of tumour necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta) and interleukin-6 (IL-6) by morphologically normal and inflamed intestinal mucosa from patients with Crohn's disease. RESULTS: Organ cultures of intestinal biopsy specimens taken from areas of affected mucosa from patients with Crohn's disease spontaneously produced increased amounts of TNF-alpha, IL-1 beta, and IL-6 compared with controls but also biopsy specimens taken in macroscopically and microscopically unaffected areas in the same patients. Concentrations of IL-1 beta and IL-6 measured in the supernatant fluid of biopsy cultures were positively correlated with the degree of tissue involvement measured by both endoscopic and histological grading. By contrast, TNF-alpha concentrations were not correlated to endoscopic and histological grading. CONCLUSIONS: These consistently raised TNF-alpha, IL-1 beta and IL-6 secretions by normal appearing mucosa from patients with Crohn's disease provide evidence for a sustained immune stimulation in Crohn's disease even in the absence of patent inflammation. The results shed a new light on the role of inflammatory cytokines in the onset of intestinal tissue damage in Crohn's disease and suggest that the range of intestinal lesions in Crohn's disease may be wider than suspected on the basis of regular endoscopic and histological examinations.

Adult↗
PubMed1996

Adenosine causes cAMP-dependent activation of chick embryo red cell carbonic anhydrase and 2,3-DPG synthesis.

In late chick embryos, coordinate activation of red cell carbonic anhydrase II (CAII) and 2,3-diphosphoglycerate (2,3-DPG) synthesis is initiated by hypoxia. The effects are mediated by unidentified hormonal effectors resident in chick plasma. In the present investigation, we have analyzed the effect of adenosine receptor stimulation on embryonic red cell CAII and 2,3-DPG synthesis. We find that primitive and definitive embryonic red blood cells from chick have an A2a adenosine receptor. Stimulation of the receptor with metabolically stable adenosine analogues causes a large increase of red cell adenosine 3',5'-cyclic monophosphate (cAMP) and subsequent activation of red cell CAII and 2,3-DPG production in definitive red blood cells and of CAII synthesis in primitive red blood cells. Direct stimulation of adenylyl cyclase with forskolin has the same effect. Analysis of red cell protein pattern after labeling with [35S]methionine shows that stimulation of red cell cAMP levels activates synthesis of several other proteins aside from CAII. Presence of actinomycin D inhibits cAMP-dependent changes of protein synthesis, indicating that cAMP-dependent transcriptional activation is required. In contrast to the stable adenosine receptor analogues, adenosine itself was a very weak agonist, unless its metabolism was significantly inhibited. Thus, besides adenosine, other effectors of the adenylyl cyclase system are likely to be involved in the O2 pressure-dependent regulation of red cell metabolism in late development of avian embryos.

2,3-Diphosphoglycerate↗
PubMed1996

Norepinephrine-mediated hypoxic stimulation of embryonic red cell carbonic anhydrase and 2,3-DPG synthesis.

Hypoxia is the stimulus for activation of red cell carbonic anhydrase II (CAII) and 2,3-diphosphoglycerate (2,3-DPG) synthesis of chick red blood cells during late embryonic development. We have tested whether plasma catecholamines are involved as hormonal mediators, because hypoxia is a well-known stimulus for catecholamine release in mammalian fetuses. Plasma catecholamines were measured in 8- to 16-day-old chick embryos. Plasma levels of norepinephrine (NE) were initially low, but its concentration increased rapidly from 2.7 nM (day 12) to 13.4 nM at day 13 and 25.5 nM at day 16. Epinephrine (E) was not detectable before day 13. Short-term hypoxic exposure of day 11 embryos (1-h incubation at 13.5% O2) increased plasma NE concentration fivefold compared with the controls but had no effect on E. During 15-h in vitro incubation of red blood cells from day 11, addition of 1 microM NE to the incubation medium increased the red cell 2,3-DPG concentration nearly threefold and CAII activity sixfold compared with the control. The CAII activity and 2,3-DPG concentration were also increased when cells were incubated with plasma from late chick embryos. The activation was induced by beta-adrenergic stimulation of adenylyl cyclase. Atenolol and propranolol blocked the effects of NE and embryonic chick plasma. Analysis of de novo protein synthesis ([35S]methionine incorporation) demonstrated that catecholamines stimulate the synthesis of several proteins besides CAII. The results indicate that developmental changes of plasma NE concentration are instrumental in the adenosine 3',5'-cyclic monophosphate-dependent activation of CAII and 2,3-DPG synthesis of red blood cells from late chick embryos.

2,3-Diphosphoglycerate↗
PubMed1996

Unusual presentation of Takayasu arteritis with cardiac involvement and imitation of juvenile arteriosclerosis. A case report.

A twenty-five-year-old Caucasian man with Takayasu arteritis, who was formerly diagnosed as suffering from premature arteriosclerosis, is described. Necropsy disclosed involvement of the entire aorta and its major branches, the pulmonary arteries, the coronary arteries, the intramyocardial arteries, and the heart valves, a combination hitherto not described. Literature concerning heart involvement in Takayasu arteritis is reviewed, and the differential diagnosis is discussed.

Adult↗
PubMed1996

Force feedback for virtual reality based minimally invasive surgery simulator.

This paper presents ongoing research towards an endoscopic surgery simulation system. Our specific application of interest is laparoscopic surgery. The goal is to conceive an endoscopic surgical training tool which allows to realistically simulate the interactions between one or several surgical instruments and the gastrointestinal organs in a virtual reality based environment. An artificial patient is being developed into which endoscopic surgical instruments can be inserted to operate upon virtual organs displayed on a video monitor. In order to achieve a faithful and precise simulation, not only a realistic graphical representation of the organic tissue and its behavior is needed, but also the forces and moments on the surgical instruments encountered during an operation are required to be simulated. The laparoscopic surgery simulator must therefore provide force feedback through the endoscopic instruments manipulated by the surgeon. This paper details the mechanical design of the force feedback mechanisms and addresses some of the technical challenges of this project.

Computer Simulation↗
PubMed1996

Interleukin-6 and soluble interleukin-6 receptor in peritoneal fluid and serum of patients with endometriosis.

OBJECTIVE: Interleukin-6 (IL-6) and soluble Interleukin-6-receptor (sIL-6R) concentrations were investigated in patients with endometriosis and other benign gynecologic diseases. METHODS: During laparoscopy or laparotomy peritoneal fluid and serum were collected from 29 patients with endometriosis, 31 patients with benign ovarian masses and 4 patients with chronic inflammation or adhesions. Interleukin-6 (IL-6) concentrations were determined by Elisa-technique. RESULTS: Patients with endometriosis stage IV revealed slightly higher IL-6 concentrations in peritoneal fluid when compared to patients with stage I to II disease and ovarian masses/ chronic inflammation. IL-6 serum concentrations were higher in case of stage I and II when compared to stage III and IV and ovarian masses/chronic inflammation. Patients with endometriosis revealed significantly higher sIL-6 receptor concentrations in peritoneal fluid and serum as compared to patients with ovarian cysts and chronic inflammation. CONCLUSION: IL-6 and soluble IL-6 receptor may be considered to be involved in endometriosis. However, the patho-physiologic mechanism must be the subject of further investigation.

Adolescent↗
PubMed1995

Invasiveness of endometriotic cells in vitro.

The pathogenesis of endometriosis is not known. The currently favoured theory is that viable endometrial cells, shed from the endometrium into the pelvic cavity by retrograde menstruation, reattach and invade other tissues. We used a collagen gel invasion assay to assess invasive potential of endometriotic cells. The invasion indices of cells from peritoneal endometriotic lesions and a metastatic bladder carcinoma cell line (EJ28) were similar (2.2-15.6 vs 8.4-11.6) whereas cells from normal endometrium and non-metastatic carcinoma cells (RT112) were non-invasive (indices < 1). Invasiveness of endometriotic cells might contribute to the pathogenesis of endometriosis.

Endometriosis↗
PubMed1995

Restoration of the Epstein-Barr virus ZEBRA protein's capacity to disrupt latency by the addition of heterologous activation regions.

The ZEBRA protein has a unique biological function among herpesviral proteins. It is responsible for the disruption of Epstein-Barr virus (EBV) latency and the induction of the lytic cycle. ZEBRA is a bZIP transcriptional activator which binds as a dimer to 7-bp response elements within EBV promoters and is directly involved in the stimulation of virus replication at the EBV lytic origin. We have employed the ZEBRA/EBV biological system to test whether a heterologous activation domain can substitute for another activation domain (the ZEBRA domain). The ZEBRA activation region was replaced with the potent acid activation region from the herpes simplex virus VP16 protein or with the activation region of the EBV R protein. Both chimeras were found to transactivate model and native promoters at equivalent or better levels than ZEBRA itself. Activation was not target- or cell-type dependent, nor was it dependent on the presence of virus. These activation domains restored ZEBRA's ability to induce early antigen and to stimulate origin replication to levels that were equal to or greater than those of wild type. These studies suggest that the specificities of some of the known biological functions of ZEBRA are not dependent upon the nature of the activation domain present within ZEBRA.

B-Lymphocytes↗
PubMed1995

Prothrombin fragment 1 + 2 and thrombin-antithrombin III complex as markers of activation of blood coagulation in inflammatory bowel diseases.

OBJECTIVES AND METHODS: The aims of the present work were to assess the presence of thrombin generation in Crohn's disease and in ulcerative colitis by using the prothrombin fragment 1 + 2 and the thrombin-antithrombin III complex assays and to study the possible relationships between these markers and disease activity. RESULTS: Prothrombin fragment 1 + 2 and thrombin-antithrombin III complex were significantly raised in patients with Crohn's disease (n = 69) and with ulcerative colitis (n = 25) as compared with healthy controls (n = 50). In Crohn's disease these two markers of thrombin generation were correlated with the Van Hees index (P < 0.05 and P < 0.001, respectively); values were significantly different from controls even in the patient group displaying the lowest disease activity (P < 0.001). No correlation was found with tumour necrosis factor alpha and C-reactive protein; nevertheless patients with C-reactive protein less than or equal to 10 mg/l had significant lower values of prothrombin fragment 1 + 2 (P < 0.03). In ulcerative colitis prothrombin fragment 1 + 2 and thrombin-antithrombin III complex were significantly increased by comparison with controls, were higher in patients with pancolitis and correlated with C-reactive protein (P < 0.002 and P < 0.009, respectively). CONCLUSION: These data show that prothrombin fragment 1 + 2 and thrombin-antithrombin III complex are increased in inflammatory bowel diseases and suggest that thrombin generation might be an early event in their pathogenesis.

Adolescent↗
PubMed1994

Delta-opioid receptor agonists inhibit neuromuscular transmission in human colon.

The present study was undertaken to investigate the possible role of delta-opioid receptors in the neuroregulation of human colonic motility by using a superfusion model. Spontaneous mechanical activity and responses to electrical transmural nerve stimulation of both longitudinal and circular muscle strips from the human sigmoid colon were studied. Exogenously added delta-opioid receptor agonists did not modify spontaneous contractile activities of either type of strip. Nerve stimulation induced a triphasic response composed of an initial contraction followed by a relaxation and an off-contraction. This response was mediated by cholinergic excitatory nerves and non-adrenergic, non-cholinergic excitatory and inhibitory nerves. [Met5]Enkephalin and the synthetic delta-opioid receptor agonist [D-Pen2,D-Pen5]enkephalin (DPDPE) significantly decreased the amplitude of the initial contraction and of the off-contraction. The effects of both delta-opioid receptor agonists were reduced in the presence of either the delta-opioid receptor antagonist, ICI 174864, or another delta-opioid receptor antagonist, naltrindole. ICI 174864 prevented neither the effects of a natural kappa-opioid receptor agonist, dynorphin-(1-13) nor those of the mu-opioid receptor agonist, PL017. Therefore, these data suggest that delta-opioid receptors might be involved in the neuroregulation of smooth muscle of human colon and may mediate inhibition of cholinergic and non-cholinergic excitatory transmission within the myenteric plexus.

Analgesics↗
PubMed1994

Chloride and bicarbonate transport in chick embryonic red blood cells.

1. Unidirectional efflux of 36Cl- and H14CO3- from erythrocytes of 4- to 16-day-old chick embryos was measured under steady-state conditions at 37 degrees C and pH 7.7. The efflux rates were high, > 3 s-1, and were, therefore, measured by means of the continuous flow tube method. 2. At day 4 of development the range of permeability coefficients for bicarbonate and chloride (PHCO3 and PCl was 1-30 x 10(-4) cm s-1, with average values of respectively 10 x 10(-4) and 8 x 10(-4) cm s-1. However, the results can be divided into two groups, one with PHCO3 and PCl above 12 x 10(-4) cm s-1, and one with values below 5 x 10(-4) cm s-1. The same range of values was also obtained for day 6 erythrocytes, but the overlap is more conspicuous. At day 16, PHCO3 and PCl were respectively 9 x 10(-4) and 6 x 10(-4) cm s-1 (37 degrees C, pH 7.7). In adult chicken red blood cells PHCO3 and PCl were respectively 7 x 10(-4) and 4 x 10(-4) cm s-1, and in human red blood cells the respective values were 5.6 x 10(-4) and 4 x 10(-4) cm s-1. 3. Chloride self-exchange, measured at 0 degrees C, was almost completely inhibited by addition of 1 mM 4,4'-diisothiocyanostilbene-2,2'-disulphonate (DIDS) at both days 6 and 16 of embryonic development, supporting the finding that the embryonic chick erythrocytes also have a transmembrane anion exchanger similar to that of other red cells.(ABSTRACT TRUNCATED AT 250 WORDS)

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗