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Biomedical subjects

H Barth

Publications and source records attributed to H Barth.

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

L-tryptophan contaminant 'peak E' induces the release of IL-5 and IL-10 by peripheral blood mononuclear cells from patients with functional somatic syndromes.

In 1989, the development of eosinophilia myalgia syndrome (EMS) was observed in some patients after the intake of l-tryptophan containing several contaminants, including 1,1'-ethylidenebis[l-tryptophan] ('peak E'). Since l-tryptophan has been taken particularly by individuals suffering from functional somatic syndromes (FSS), such as fibromyalgia syndrome (FMS), we put forward the hypothesis that EMS may have developed preferentially in patients with FSS as an allergic reaction towards the contaminant peak E. We therefore studied the immunological reactivity towards l-tryptophan and peak E in these individuals (n = 12) and compared these data with those obtained in 12 healthy controls and 12 patients with other chronic disorders. Peripheral blood mononuclear cells (PBMC) were cultured for 7 days with pure l-tryptophan and peak E. Supernatant fluids were collected at day 7. The type 2 cytokines IL-4, IL-5 and IL-10, and the type 1 cytokines IL-2 and IFN-gamma, were determined by a double sandwich ELISA. PBMC from seven of the 12 FSS patients, but only three of the 24 controls, produced cytokines after incubation with peak E (P < 0.05). Interestingly, six of the seven FSS patients reacting with peak E produced IL-5 and/or IL-10. In contrast, PBMC from only one patient with other chronic disorders and one healthy control secreted type 2 cytokines in response to peak E. The observed heightened type 2 reactivity towards the more immunogenic contaminant 1,1'-ethylidenebis[l-tryptophan] in FSS patients may therefore be taken as an additional argument for our concept that EMS may have developed as a kind of drug-induced allergic disease.

Adult↗
PubMed2001

Fetal cardiac effects of doxorubicin therapy for carcinoma of the breast during pregnancy: case report and review of the literature.

Cardiotoxicity is a recognized complication of anthracycline drugs given as part of chemotherapy; however, the pre- and postnatal cardiac effects of in utero exposure are not well documented. In this report we present a case of gestational breast cancer with initiation of four cycles of doxorubicin/cyclophosphamide chemotherapy after modified radical mastectomy and axilla dissection during the early second trimester. Serial echocardiographic measurements of the ventricular shortening fraction and biometry of the ventricular cavities were performed. Allowing for the individual variability of these values in the fetus no myocardial dysfunction was observed. The literature was reviewed in an attempt to delineate the possible role of prenatal echocardiography in the diagnosis of doxorubicin-induced cardiotoxicity in the fetus.

Adult↗
PubMed2001

Characterization of the enzymatic component of the ADP-ribosyltransferase toxin CDTa from Clostridium difficile.

Certain strains of Clostridium difficile produce the ADP-ribosyltransferase CDT, which is a binary actin ADP-ribosylating toxin. The toxin consists of the binding component CDTb, which mediates receptor binding and cellular uptake, and the enzyme component CDTa. Here we studied the enzyme component (CDTa) of the toxin using the binding component of Clostridium perfringens iota toxin (Ib), which is interchangeable with CDTb as a transport component. Ib was used because CDTb was not expressed as a recombinant protein in Escherichia coli. Similar to iota toxin, CDTa ADP-ribosylates nonmuscle and skeletal muscle actin. The N-terminal part of CDTa (CDTa1-240) competes with full-length CDTa for binding to the iota toxin binding component. The C-terminal part (CDTa244-263) harbors the enzyme activity but was much less active than the full-length CDTa. Changes of Glu428 and Glu430 to glutamine, Ser388 to alanine, and Arg345 to lysine blocked ADP-ribosyltransferase activity. Comparison of CDTa with C. perfringens iota toxin and Clostridium botulinum C2 toxin revealed full enzyme activity of the fragment Ia208-413 but loss of activity of several N-terminally deleted C2I proteins including C2I103-431, C2I190-431, and C2I30-431. The data indicate that CDTa belongs to the iota toxin subfamily of binary actin ADP-ribosylating toxins with respect to interaction with the binding component and substrate specificity. It shares typical conserved amino acid residues with iota toxin and C2 toxin that are suggested to be involved in NAD-binding and/or catalytic activity. The enzyme components of CDT, iota toxin, and C2 toxin differ with respect to the minimal structural requirement for full enzyme activity.

ADP Ribose Transferases↗
PubMed2001

Cellular uptake of the Clostridium perfringens binary iota-toxin.

The binary iota-toxin is produced by Clostridium perfringens type E strains and consists of two separate proteins, the binding component iota b (98 kDa) and an actin-ADP-ribosylating enzyme component iota a (47 kDa). Iota b binds to the cell surface receptor and mediates the translocation of iota a into the cytosol. Here we studied the cellular uptake of iota-toxin into Vero cells. Bafilomycin A1, but not brefeldin A or nocodazole, inhibited the cytotoxic effects of iota-toxin, indicating that toxin is translocated from an endosomal compartment into the cytoplasm. Acidification (pH < or = 5.0) of the extracellular medium enabled iota a to directly enter the cytosol in the presence of iota b. Activation by chymotrypsin induced oligomerization of iota b in solution. An average mass of 530 +/- 28 kDa for oligomers was determined by analytical ultracentrifugation, indicating heptamer formation. The entry of iota-toxin into polarized CaCo-2 cells was studied by measuring the decrease in transepithelial resistance after toxin treatment. Iota-toxin led to a significant decrease in resistance when it was applied to the basolateral surface of the cells but not following application to the apical surface, indicating a polarized localization of the iota-toxin receptor.

ADP Ribose Transferases↗
PubMed2001

Stroke pattern interpretation: the variability of hypertensive versus amyloid angiopathy hemorrhage.

INTRODUCTION: It is commonly felt that cerebral amyloid angiopathy (CAA) related intracerebral hemorrhage (ICH) can be distinguished from hypertension (HTN)-related ICH by certain typical features on computerized tomography (CT) and magnetic resonance imaging (MRI). The purpose of this study was to investigate the performance of clinicians who were asked to differentiate between CAA and HTN based on hemorrhage pattern interpretation and to assess the feasibility of such classification. METHODS: The admission scans from 83 patients who were admitted to our service with an acute ICH were presented to 5 clinicians in a randomized and blinded fashion (1 junior, and 1 senior neurosurgical resident, 1 attending neurosurgeon, and 2 neurosurgeon-neuroradiologists). There were no patients who received oral anticoagulants other than low-dose aspirin, or who suffered from vascular malformations or tumors. Scans from 41 patients with a histologically proven diagnosis of CAA and from 42 patients with a clear history of HTN were investigated. Hematoma evacuation was done in all CAA patients and in 59% of HTN patients (n = 25). RESULTS: The overall average classification accuracy was 66.8% (range: 62.7-69.9). For correct HTN classification it was 69.5% (range: 64.3-81), and 63.9% for CAA, respectively (range: 48.9-75.6). There were negligible differences in classification accuracy among all observers. Patients with a CAA-related ICH were significantly older than patients with a HTN-related ICH (74 vs. 66.5 years, p < 0.05). There was a significantly higher number of hematomas >30 ml in CAA (85.3%) when compared with HTN (59.5%). No basal ganglionic hemorrhage was seen in CAA, but in 40.5% in HTN. Intraventricular hemorrhage was seen in 24.4% in CAA, and in 26.2% in HTN. Two patients (4.9%) with CAA, and 7 patients with HTN (16.7%) presented with cerebellar hematomas. CONCLUSIONS: Three of 10 scans were not correctly diagnosed regardless of the examiner's level of training. This calls into question the reliability of classifying the underlying pathological condition based on hemorrhage pattern interpretation on CT or MRI. The definite diagnosis of CAA- versus HTN-related hemorrhage requires a histopathological confirmation and should not be based solely on hemorrhage pattern interpretation.

Adult↗
PubMed2000

Regulation of somatodendritic GABAA receptor channels in rat hippocampal neurons: evidence for a role of the small GTPase Rac1.

The role of the cytoskeleton in the activity of GABA(A) receptors was investigated in cultured hippocampal neurons. Receptor currents were measured with the whole-cell patch-clamp technique during repetitive stimulation with 1 microm muscimol. After destruction of the microtubular system with nocodazol, muscimol-induced currents showed a rundown by 78%. A similar rundown was observed when actin fibers were destroyed with latrunculin B or C2 toxin of Clostridium botulinum. Because the small GTPases of the Rho family RhoA, Rac1, and Cdc42 are known to control the organization of actin fibers, we investigated their possible involvement. Inactivation of the GTPases with clostridial toxins, as well as intracellular application of recombinant Rho GTPases, indicated that active Rac1 was necessary for full GABA(A) receptor activity. Immunocytochemical labeling of the receptors showed that the disappearance of receptor clusters in the somatic membrane as induced by muscimol stimulation was enhanced by Rac1 inactivation. It is suggested that Rac1 participates in the regulation of GABA(A) receptor clustering and/or recycling.

Actin Cytoskeleton↗
PubMed2000

Cellular uptake of Clostridium botulinum C2 toxin requires oligomerization and acidification.

The actin-ADP-ribosylating binary Clostridium botulinum C2 toxin consists of two individual proteins, the binding/translocation component C2II and the enzyme component C2I. To elicit its cytotoxic action, C2II binds to a receptor on the cell surface and mediates cell entry of C2I via receptor-mediated endocytosis. Here we report that binding of C2II to the surface of target cells requires cleavage of C2II by trypsin. Trypsin cleavage causes oligomerization of the activated C2II (C2IIa) to give SDS-stable heptameric structures, which exhibit a characteristic annular or horseshoe shape and form channels in lipid bilayer membranes. Cytosolic delivery of the enzyme component C2I is blocked by bafilomycin but not by brefeldin A or nocodazole, indicating uptake from an endosomal compartment and requirement of endosomal acidification for cell entry. In the presence of C2IIa and C2I, short term acidification of the extracellular medium (pH 5.4) allows C2I to enter the cytosol directly. Our data indicate that entry of C2 toxin into cells involves (i) activation of C2II by trypsin-cleavage, (ii) oligomerization of cleaved C2IIa to heptamers, (iii) binding of the C2IIa oligomers to the carbohydrate receptor on the cell surface and assembly with C2I, (iv) receptor-mediated endocytosis of both C2 components into endosomes, and finally (v) translocation and release of C2I into the cytosol after acidification of the endosomal compartment.

Acids↗
PubMed2000

Ephrin-A5 induces collapse of growth cones by activating Rho and Rho kinase.

The ephrins, ligands of Eph receptor tyrosine kinases, have been shown to act as repulsive guidance molecules and to induce collapse of neuronal growth cones. For the first time, we show that the ephrin-A5 collapse is mediated by activation of the small GTPase Rho and its downstream effector Rho kinase. In ephrin-A5-treated retinal ganglion cell cultures, Rho was activated and Rac was downregulated. Pretreatment of ganglion cell axons with C3-transferase, a specific inhibitor of the Rho GTPase, or with Y-27632, a specific inhibitor of the Rho kinase, strongly reduced the collapse rate of retinal growth cones. These results suggest that activation of Rho and its downstream effector Rho kinase are important elements of the ephrin-A5 signal transduction pathway.

ADP Ribose Transferases↗
PubMed2000

The golgi-associated COPI-coated buds and vesicles contain beta/gamma -actin.

It has been shown previously that the morphology and subcellular positioning of the Golgi complex is controlled by actin microfilaments. To further characterize the association between actin microfilaments and the Golgi complex, we have used the Clostridium botulinum toxins C2 and C3, which specifically inhibit actin polymerization and cause depolymerization of F-actin in intact cells by the ADP ribosylation of G-actin monomers and the Rho small GTP-binding protein, respectively. Normal rat kidney cells treated with C2 showed that disruption of the actin and the collapse of the Golgi complex occurred concomitantly. However, when cells were treated with C3, the actin disassembly was observed without any change in the organization of the Golgi complex. The absence of the involvement of Rho was further confirmed by the treatment with lysophosphatidic acid or microinjection with the constitutively activated form of RhoA, both of which induced the stress fiber formation without affecting the Golgi complex. Immunogold electron microscopy in normal rat kidney cells revealed that beta- and gamma-actin isoforms were found in Golgi-associated COPI-coated buds and vesicles. Taken together, the results suggest that the Rho signaling pathway does not directly regulate Golgi-associated actin microfilaments, and that beta- and gamma-actins might be involved in the formation and/or transport of Golgi-derived vesicular or tubular intermediates.

ADP Ribose Transferases↗
PubMed2000

Binding of Clostridium botulinum C2 toxin to asparagine-linked complex and hybrid carbohydrates.

Clostridium botulinum C2 toxin is a binary toxin composed of an enzymatic subunit (C2I) capable of ADP-ribosylating actin and a binding subunit (C2II) that is responsible for interaction with receptors on eukaryotic cells. Here we show that binding of C2 toxin depends on the presence of asparagine-linked carbohydrates. A recently identified Chinese hamster ovary cell mutant (Fritz, G., Schroeder, P., and Aktories, K. (1995) Infect. Immun. 63, 2334-2340) was found to be deficient in N-acetylglucosaminyltransferase I. C2 sensitivity of this mutant was restored by transfection of an N-acetylglucosaminyltransferase I cDNA. C2 toxin sensitivity was reduced after inhibition of alpha-mannosidase II. In contrast, Chinese hamster ovary cell mutants deficient in sialylated (Lec2) or galactosylated (Lec8) glycoconjugates showed an increase in toxin sensitivity compared with wild-type cells. Our results show that the GlcNAc residue linked beta-1,2 to the alpha-1,3-mannose of the asparagine-linked core structure is essential for C2II binding to Chinese hamster ovary cells.

Animals↗
PubMed2000

Giant cystic craniopharyngiomas with extension into the posterior fossa.

Between 1991 and 1998, 24 patients underwent surgery for a craniopharyngioma in our department. This group included two patients who had tumors with extensive growth along the midline, and along the posterior fossa in particular. In both cases suprasellar calcifications were typical features on magnetic resonance imaging (MRI) and computed tomography (CT). A 7-year-old boy presented with a 6-month history of headache, nausea, and progressive unilateral hearing loss. With a suboccipital approach it was possible to remove the main part of the tumor. In a 13-year-old boy headache and visual deterioration led to the diagnosis of a craniopharyngioma, which was removed with a pterional approach. For the neuroimaging work-up in such cases of atypically growing craniopharyngiomas MRI is the method of choice. Additional CT scanning is recommended, which provides valuable information about bony changes at the skull base due to space-occupying growth. CT substantiates the differential diagnosis if typical calcifications are seen.

Adolescent↗
PubMed2000

Spontaneous intracranial haematomas caused by neoplasms.

We report about 50 patients with spontaneous intracerebral haematomas (ICH) caused by intracranial neoplasms to assess the underlying histological condition, their presentation on admission, diagnostic work-up, treatment, histological diagnosis, and clinical outcome. These patients were identified in a prospective series of 2041 patients with intracranial neoplasms and 692 patients with spontaneous ICH, which were both consecutively collected over a nine-year-period. The frequency of ICH in patients with intracranial neoplasms was 2.4%. The frequency of tumour related ICH in the ICH group was 7.2%. The leading cause of tumour related ICH were metastases of extracranial origin (n = 18; 36%), followed by glioblastoma multiforme (n = 15; 30%). Nine patients (18%) had benign primary intracranial neoplasms. On admission 18 patients were somnolent (36%) and 14 patients (28%) were comatose. In 29 cases (58%) ICH was the first clinical sign of neoplastic disease, while in 21 patients (42%) a malignant tumour was already known. We operated on 45 patients (90%), four patients (8%) were not operated on because of poor clinical condition and died, one patient refused surgical treatment. Six patients (12%) died despite surgery. This series confirms the importance of a proper neuroradiological and clinical work-up of patients with suspected tumour related ICH followed by operative treatment and histological confirmation of the diagnosis. This is supported by the fact that 18% of patients had prognostically favourable intracranial tumours which would not otherwise have been adequately treated.

Acute Disease↗
PubMed2000

Three-dimensional (3-D) ultrasonography for obtaining the four and five-chamber view: comparison with cross-sectional (2-D) fetal sonographic screening.

OBJECTIVES: To assess the ability of Doppler-gated 3-D fetal echocardiography to reconstruct and display specific cardiac structures routinely visualized during antenatal ultrasound in a population at low risk for cardiac anomalies. To determine whether any advantage is offered by 3-D sonographic cardiac examination over conventional sonographic fetal screening techniques. DESIGN: After routine two-dimensional sonographic examination, 3-D cardiac data were collected prospectively in 30 fetuses with gestational ages between 19 and 23 weeks from a low risk patient population. Basic echocardiographic key views were derived from 3-D data and selected for reconstruction and analysis. Four- and five-chamber views were rated and only those views judged to be well visualized were considered as positive results. RESULTS: The four- and five-chamber views were well visualized in all but one fetus using conventional 2-D imaging. Gated 3-D volume data sets enabled visualization of these structures in only 19 of 30 fetuses but provided additional structural depth and allowed a dynamic 3-D perspective of valvar morphology and ventricular wall motion. The right ventricular outflow tract was available from the 3-D volumes in 16 subjects. CONCLUSIONS: Considering the versatility of gated 3-D fetal cardiac imaging we believe that it may soon become an important component of fetal screening thus helping to retrieve standard cardiac cross sections when 2-D imaging is limited by lack of sonographer experience or sonographic windows. Diagnostically acceptable echocardiographic views were obtained more consistently with 2-D ultrasound than with 3-D volume data.

Echocardiography, Doppler↗
PubMed2000

Hypereosinophilia induced by high-dose intratumoral and peritumoral mistletoe application to a patient with pancreatic carcinoma.

UNLABELLED: A patient with inoperable adenocarcinoma of the pancreas was treated with intraperitumoral and peritumoral injections of a Viscum album L. extract containing 5,700 ng/mL mistletoe lectin, mainly mistletoe lectin 1 (Abnobaviscum Quercus 2) for 5 weeks (1 injection per week). After the third injection (day 22), a marked eosinophilia was observed (1,800 per microliter) that rose to 3,268 per microliter after the fifth injection (day 42). Furthermore, histology performed on day 28 revealed accumulation of eosinophils in ductal lesions and adjacent stroma in addition to the features of ductal adenocarcinoma. In order to investigate whether eosinophilia correlated with immunological features, we analyzed cytokine production of peripheral blood mononuclear cells (PBMC) from this patient after stimulation with antigens known to "unmask" an individual's predisposition for defined immunoreactions, namely purified protein derivative (PPD) as a stimulator of T-helper (TH1)1-cells and tetanus toxoid (TT) as an activator of TH2-cells. PBMC of the patient showed a strong proliferation and production of interleukin (IL)-5 and IL-10 after incubation with TT indicating a type-2 response. Simultaneously, PBMC were induced to proliferate and produce interferon gamma (IFN-gamma) by incubation with PPD suggesting also a type-1 response. These data would readily explain the eosinophilia because eosinophils are effector cells of type-2 reaction but also require type-1 cytokines. Although the overall clinical course of the patient was rapidly progressive, temporary stabilization of the patient's general condition during mistletoe treatment was observed. It is, however, still an open question whether this transient benefit was due to the induction of eosinophilia by a type-2 response. CONCLUSION: Before high-dose intratumoral and peritumoral treatment with a Viscum album L. extract containing mistletoe, lectin 1 can be associated with hypereosinophilia and strong production of TH1 as TH2 cytokines as well.

Adenocarcinoma↗
PubMed2000

The C terminus of component C2II of Clostridium botulinum C2 toxin is essential for receptor binding.

The binary Clostridium botulinum C2 toxin consists of two separate proteins, the binding component C2II (80.5 kDa) and the actin-ADP-ribosylating enzyme component C2I (49.4 kDa). For its cytotoxic action, C2II binds to a cell membrane receptor and induces cell entry of C2I via receptor-mediated endocytosis. Here we studied the structure-function relationship of C2II by constructing truncated C2II proteins and producing polyclonal antisera against selective regions of C2II. An antibody raised against the C terminus (amino acids 592 to 721) of C2II inhibited binding of C2II to cells. The antibody prevented pore formation by C2II oligomers in artificial membranes but did not influence the properties of existing channels. To further define the region responsible for receptor binding, we constructed proteins with deletions in C2II; specifically, they lacked amino acid residues 592 to 721 and the 7 C-terminal amino acid residues. The truncated proteins still formed sodium dodecyl sulfate-stable oligomers but were unable to bind to cells. Our data indicate that the C terminus of C2II mediates binding of the protein to cells and that the 7 C-terminal amino acids are structurally important for receptor binding.

Binding Sites↗
PubMed2000

Regulated von Willebrand factor secretion is associated with agonist-specific patterns of cytoskeletal remodeling in cultured endothelial cells.

von Willebrand factor (vWF), an adhesive glycoprotein involved in primary hemostasis, is stored and released from endothelial secretory granules called Weibel-Palade bodies. Regulated secretion occurs in reaction either to [Ca(2+)](i)-raising agents (histamine or thrombin) or to cAMP-raising agents (epinephrine, adenosine, or forskolin). We investigated the pattern of release and the cytoskeletal requirements for secretion in response to these 2 classes of agonists. Secretion induced by [Ca(2+)](i)-raising agents involves peripheral and central granules and is inhibited by colchicine-induced microtubule disruption. It is accompanied by Rho-dependent stress fiber formation and cell retraction. Secretion and remodeling occur in the same individual cells. However, secretion is potentiated by cytochalasin E and C3 toxin, indicating that stress fiber formation antagonizes vWF secretion. In contrast, vWF secretion induced by cAMP-raising agents involves the release of only peripheral granules (implying less vWF release on a per cell basis) and is not inhibited by microtubule disruption. cAMP-mediated secretion is accompanied by disruption of stress fibers, strengthening of the cortical actin rim, and preservation of cell-cell contacts. It is unaffected by cytochalasins or C3 toxin. In contrast to [Ca(2+)](i)-raising agents, cAMP-raising agents induce secretion without cell retraction/intercellular gap formation. Thus, they are likely to play a physiological role in the regulation of endothelial vWF secretion and, therefore, of plasma vWF levels.

ADP Ribose Transferases↗
PubMed1999

Neosynthesis and activation of Rho by Escherichia coli cytotoxic necrotizing factor (CNF1) reverse cytopathic effects of ADP-ribosylated Rho.

Clostridium botulinum exoenzyme C3 inactivates the small GTPase Rho by ADP-ribosylation. We used a C3 fusion toxin (C2IN-C3) with high cell accessibility to study the kinetics of Rho inactivation by ADP-ribosylation. In primary cultures of rat astroglial cells and Chinese hamster ovary cells, C2IN-C3 induced the complete ADP-ribosylation of RhoA and concomitantly the disassembly of stress fibers within 3 h. Removal of C2IN-C3 from the medium caused the recovery of stress fibers and normal cell morphology within 4 h. The regeneration was preceded by the appearance of non-ADP-ribosylated RhoA. Recovery of cell morphology was blocked by the proteasome inhibitor lactacystin and by the translation inhibitors cycloheximide and puromycin, indicating that intracellular degradation of the C3 fusion toxin and the neosynthesis of Rho were required for reversal of cell morphology. Escherichia coli cytotoxic necrotizing factor CNF1, which activates Rho by deamidation of Gln(63), caused reconstitution of stress fibers and cell morphology in C2IN-C3-treated cells within 30-60 min. The effect of CNF1 was independent of RhoA neosynthesis and occurred in the presence of completely ADP-ribosylated RhoA. The data show three novel findings; 1) the cytopathic effects of ADP-ribosylation of Rho are rapidly reversed by neosynthesis of Rho, 2) CNF1-induced deamidation activates ADP-ribosylated Rho, and 3) inhibition of Rho activation but not inhibition of Rho-effector interaction is a major mechanism underlying inhibition of cellular functions of Rho by ADP-ribosylation.

Adenosine Diphosphate Ribose↗