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M Brunner

Publications and source records attributed to M Brunner.

At least 91 records · Page 5Linked to original sources
PubMed1998

Direct assessment of peripheral pharmacokinetics in humans: comparison between cantharides blister fluid sampling, in vivo microdialysis and saliva sampling.

AIMS: Skin blister fluid sampling, in vivo microdialysis and saliva sampling are commonly employed as surrogates for the measurement of drug concentrations in peripheral compartments. Although expected to exhibit comparable results, data derived from these techniques have never been directly compared. Thus, the aim of the present study was to evaluate the comparability of these techniques. METHODS: Paracetamol, a model drug with low protein binding, was administered to seven healthy volunteers at an oral dose of 2000 mg. Subsequently, tissue kinetics were measured simultaneously in cantharides induced skin blisters, microdialysates of subcutaneous- and skeletal muscle-tissue and saliva and compared to serum concentrations. RESULTS: Mean ratio (AUCblister/AUCserum) was 0.88 (95% CI, 0.50-1.26), mean ratio (AUCmuscle/AUCserum) was 1.08 (0.67-1.49), mean ratio (AUCsubcutaneous/AUCserum) was 0.96 (0.41-1.51) and mean ratio (AUCsaliva/AUCserum) was 1.83 (1.39-2.27). In this study the concentration profiles after single oral administration differed among the three methods. The time course of the concentration (peripheral compartment)/concentration (serum)-ratios showed that cantharides blister and microdialysate concentrations closely paralleled serum levels. An equilibration period of less than 2 h had to be taken into account for blister measurements. In contrast, saliva concentrations were significantly higher than corresponding serum concentrations. CONCLUSIONS: Skin blister sampling and microdialysis closely mirrored corresponding serum concentrations and, thus, proved to be suitable techniques for the assessment of peripheral compartment pharmacokinetics. In contrast, saliva data overestimated the corresponding serum concentrations.

Acetaminophen↗
PubMed1998

Immunoglobulin M capture assay for serologic confirmation of early Lyme disease: analysis of immune complexes with biotinylated Borrelia burgdorferi sonicate enhanced with flagellin peptide epitope.

We previously reported on the efficacy of the enzyme-linked immunoglobulin M capture immune complex (IC) biotinylated antigen assay (EMIBA) for the seroconfirmation of early Lyme disease and active infection with Borrelia burgdorferi. In earlier work we identified non-cross-reacting epitopes of a number of B. burgdorferi proteins, including flagellin. We now report on an improvement in the performance of EMIBA with the addition of a biotinylated form of a synthetic non-cross-reacting immunodominant flagellin peptide to the biotinylated B. burgdorferi B31 sonicate antigen source with the avidin-biotinylated peroxidase complex detection system used in our recently developed indirect IgM-capture immune complex-based assay (EMIBA). As in our previous studies, the enzyme-linked immunosorbent assay (ELISA) reactivities of antibodies liberated from circulating ICs (by EMIBA) were compared with those of antibodies in unprocessed serum (antibodies found free in the serum, thus as an IgM-capture ELISA, but not EMIBA, because the antibodies were not liberated from ICs), the sample usually used in standard ELISAs and Western blot assays. The addition of the flagellin epitope enhanced the ELISA signal obtained with untreated sera from many Lyme disease patients but not from healthy controls. In tests with both free antibodies and ICs, with or without the addition of the flagellin epitope to the sonicate, we found the most advantageous combination was IC as the source of antibodies and sonicate plus the flagellin epitope as the antigen. In a blinded study of sera obtained from patients with early and later-phase Lyme disease, EMIBA with the enhanced antigenic preparation compared favorably with other serologic assays, especially for the confirmation of early disease.

Antibodies, Bacterial↗
PubMed1997

Functional cooperation and stoichiometry of protein translocases of the outer and inner membranes of mitochondria.

The qualitative relationship between preprotein translocases in the mitochondrial outer and inner membranes was determined by both a functional analysis and a determination of characteristic components of the translocases. Translocation contact sites of isolated mitochondria were saturated with intermediates of a matrix-targeted precursor of the beta-subunit of the F1-ATPase (pF1beta), and import of preproteins into the different mitochondrial subcompartments was monitored. A strong inhibition (75-95%) was observed for preproteins with an N-terminal matrix targeting signal, indicating that a significant portion of the contact sites was blocked by accumulated F1beta. Insertion of preproteins into the outer membrane and import into the intermembrane space of preproteins without matrix targeting signals was inhibited by about 45%, indicating that functional outer membrane translocases were available despite saturation of contact sites. Similarly, import of members of the mitochondrial carrier family into the inner membrane was only partly inhibited (40-50%), demonstrating that functional Tim22 translocases were available to cooperate with the Tom machinery in the import of carrier proteins. The stoichiometry of Tom40, Tim23, and Tim22 in mitochondria was determined to be 5:1:0.22. We conclude that translocases of the outer membrane are present in excess over translocases of the inner membrane.

Biological Transport↗
PubMed1997

Yeast mitochondrial F1F0-ATPase: the novel subunit e is identical to Tim11.

We report here the identification of the novel subunit of the mitochondrial F1F0-ATPase from Saccharomyces cerevisiae, ATPase subunit e. Yeast ATPase subunit e displays significant similarities in both amino acid sequence, properties (hydropathy and predicted coiled-coil structure) and orientation in the inner membrane, with previously identified mammalian ATPase subunit e proteins. Estimation of its native molecular mass and ability to be co-immunoprecipitated with a subunit of the F1-ATPase, demonstrate that subunit e is a subunit of the F1F0-ATPase. Stable expression of subunit e requires the presence of the mitochondrially encoded subunits of the F0-ATPase. Subunit e had been previously identified as Tim11 and was proposed to be involved in the process of sorting of proteins to the mitochondrial inner membrane.

Amino Acid Sequence↗
PubMed1997

Diclofenac concentrations in defined tissue layers after topical administration.

INTRODUCTION: To date it is unclear whether therapeutic concentrations are attained in target tissues after topical administration of nonsteroidal anti-inflammatory drugs. Therefore this study in healthy volunteers was undertaken to measure diclofenac concentrations attained in defined tissue layers directly underlying the site of topical diclofenac application by in vivo microdialysis. METHODS: In each experiment two microdialysis probes were inserted, one into a superficial (3.9 +/- 0.3 mm) and one into a deep (9.3 +/- 0.5 mm) tissue layer, in 20 healthy volunteers and calibrated in vivo. The distance between the surface of the skin and the tips of the microdialysis probes was measured by 7.5 MHz ultrasound. Diclofenac was administered topically as a single dose of approximately 300 mg/100 cm2. Concentration versus time profiles in tissue layers were monitored for 5 hours. RESULTS: Concentration versus time profiles were obtained in 11 of 20 experiments. However, there was no correlation between area under the concentration-time curve (AUC) in a defined layer and the depth of probe insertion. In those experiments where concentration versus time profiles were obtained for both probes mean AUC was 532 +/- 197 microg x min x ml(-1) for superficial layers, and 438 +/- 249 microg x min x ml(-1) for deep layers. CONCLUSION: We conclude that transdermal penetration of diclofenac, at least after single doses, is not predictable and may strongly be influenced by individual skin properties.

Administration, Cutaneous↗
PubMed1997

In vivo drug-response measurements in target tissues by microdialysis.

To study the suitability of the microdialysis technique for the measurement of target tissue pharmacodynamics in humans, the model compounds theophylline, milrinone, and compound 48/80 were administered locally by means of reversed microdialysis to the interstitial space of skeletal muscle or skin in 24 healthy volunteers. Simultaneously, interstitial concentrations of cyclic adenosine monophosphate (cAMP; as an indicator of phosphodiesterase activity) were measured in skeletal muscle, and interstitial concentrations of histamine (as an indicator of mast cell release) were measured in skin. In muscle, reversed microdialysis with milrinone led to a dose-dependent increase in interstitial cAMP concentrations (n = 8), whereas no significant effect on cAMP was observed for theophylline versus placebo (1.63 +/- 0.53 nmol/L; n = 6), even at local concentrations exceeding those attained after therapeutic doses. In skin, reversed microdialysis with compound 48/80 increased interstitial histamine concentration dose dependently versus placebo (5.99 +/- 2.74 nmol/L; n = 10). From our experiments in human skeletal muscle and skin, we concluded that microdialysis was a suitable technique for the characterization of in vivo drug response at the relevant target site. Extension of these measurements to several other human tissues is readily feasible.

Adult↗
PubMed1997

Increase by tri-iodothyronine of endothelin-1, fibronectin and von Willebrand factor in cultured endothelial cells.

Hyperthyroidism is associated with elevated plasma levels of endothelium-derived proteins such as von Willebrand factor (vWF), fibronectin (FN) and endothelin-1 (ET-1). This study was designed to characterize the mechanisms involved in this phenomenon at the cellular level. vWF, FN and ET-1 secretion and mRNA expression were measured in human umbilical vein endothelial cells (HUVECs) exposed to tri-iodothyronine (T3) for 13 +/- 1 days, using ELISA, Western blot, RIA and Northern blot analysis respectively. Exposure of HUVECs to T3 significantly increased vWF secretion (50 ng T3/ml: 117 +/- 5%, P < 0.01; 100 ng T3/ml: 127 +/- 26%, P < 0.01) as well as vWF mRNA expression (50 ng/ml: 116 +/- 13%, P < 0.001; 100 ng/ml: 136 +/- 30%, P < 0.002) (results are means +/- S.D. analysed by the Wilcoxon signed rank test). FN secretion was significantly affected by 50 (145 +/- 42% of control, P < 0.05) and 100 (116.8 +/- 16% of control, P < 0.05) ng T3/ml, and FN mRNA expression by 50 ng T3/ml (123 +/- 20%, P < 0.05). Long-term incubation with T3 increased both ET-1 secretion (25 ng/ml: 124 +/- 25%, P < 0.001; 50 ng/ml: 165 +/- 53%, P < 0.05; 100 ng/ml: 116 +/- 17%, P < 0.05) and prepro-ET-1 mRNA expression (25 ng/ml: 112 +/- 16%, P < 0.05; 50 ng/ml: 134 +/- 43%, P < 0.02; 100 ng/ml: 120 +/- 20%, P < 0.02). Protein kinase C (PKC) isoforms epsilon and beta II were not significantly affected by T3, whereas PKC alpha was increased in whole cell lysates and in membrane fractions of cells incubated with 100 but not 50 ng T3/ml. Prepro-ET-1 mRNA stability, cell numbers and proliferation, measured by [3H]thymidine assays, remained unaffected in HUVECs after exposure to T3. These data indicate thyroid hormone-induced upregulation of mRNA expression and protein synthesis of vWF, FN and ET-1, by PKC alpha-, beta II- and epsilon-independent pathways, explaining, at least in part, increased plasma concentrations of endothelial proteins and peptides in the hyperthyroid state.

Blotting, Northern↗
PubMed1997

[Ultrasound-guided transvaginal puncture of ovarian cysts].

Ultrasound-guided transvaginal aspiration of ovarian cysts offers a simple outpatient strategy for immediate pain relief and effective treatment but bears the risk of an iatrogenic spread of malignant cells. This study evaluated the cellular composition of the cyst fluids in a group of 26 sterility patients, in all of whom one or more ovarian cysts had been diagnosed and punctured. None of the patients had complications or evidence of malignant cells on cytological examination after the puncture. Only in one case dyskariotic cells were diagnosed causing an operative exploration that revealed a benign tumour. In 9 patients the ovarian cysts recurred and therefore 2 patients finally underwent an exploratory operation. In our opinion transvaginal ultrasound aspiration of functional cysts is an easy and safe procedure and may be undertaken in sterility patients in the context of specific criteria.

Adult↗
PubMed1996

Import of carrier proteins into the mitochondrial inner membrane mediated by Tim22.

Translocation of mitochondrial preproteins across the inner membrane is facilitated by the TIM machinery. Tim23 binds to matrix targeting signals and initiates membrane potential-dependent import. Tim23 and Tim17 are constituents of a translocation channel across the inner membrane. Tim44 is associated with this channel at the matrix side, and Tim44 recruits mitochondrial Hsp70 and its co-chaperone Mgel, which drive protein translocation into the matrix using ATP as an energy source. Tim22 is a new component of the import machinery of mitochondria, which shares sequence similarity with both Tim23 and Tim17. Here we report that Tim22 is required for the import of proteins of the mitochondrial ADP/ATP carrier (AAC) family into the inner membrane. Members of the yeast AAC family are synthesized without matrix targeting signals. Tim22 is in an assembly of high relative molecular mass that is distinct from the Tim23-Tim17 complex. Import of proteins of the AAC family is independent of Tim23, and import of matrix targeting signals containing preproteins is independent of Tim22.

Amino Acid Sequence↗
PubMed1996

The nucleotide exchange factor MGE exerts a key function in the ATP-dependent cycle of mt-Hsp70-Tim44 interaction driving mitochondrial protein import.

Import of preproteins into the mitochondrial matrix is driven by the ATP-dependent interaction of mt-Hsp70 with the peripheral inner membrane import protein Tim44 and the preprotein in transit. We show that Mge1p, a co-chaperone of mt-Hsp70, plays a key role in the ATP-dependent import reaction cycle in yeast. Our data suggest a cycle in which the mt-Hsp70-Tim44 complex forms with ATP: Mge1p promotes assembly of the complex in the presence of ATP. Hydrolysis of ATP by mt-Hsp70 occurs in complex with Tim44. Mge1p is then required for the dissociation of the ADP form of mt-Hsp70 from Tim44 after release of inorganic phosphate but before release of ADP. ATP hydrolysis and complex dissociation are accompanied by tight binding of mt-Hsp70 to the preprotein in transit. Subsequently, the release of mt-Hsp70 from the polypeptide chain is triggered by Mge1p which promotes release of ADP from mt-Hsp70. Rebinding of ATP to mt-Hsp70 completes the reaction cycle.

Adenosine Triphosphate↗
PubMed1996

Role of Tim23 as voltage sensor and presequence receptor in protein import into mitochondria.

Tim23, an essential component of the protein import machinery of the inner membrane of mitochondria (TIM complex), forms dimers that display a dynamic behavior. Dimer formation is promoted by the membrane potential delta psi. Binding of a matrix targeting sequence to Tim23 triggers dimer dissociation. Monomeric Tim23 is present when a preprotein chain is in transit across the TIM complex. Dimerization of Tim23 is dependent on the second half of its N-terminal hydrophilic domain, which is exposed to the intermembrane space. This segment contains a heptad leucine repeat motif with a predicted capacity for dimer formation. We propose that Tim23 exerts a key function in protein import: Tim23 dimers formed in response to delta psi act as receptors for matrix targeting sequences on the surface of the inner membrane. The ensuring dissociation of Tim23 dimer triggers opening of the TIM channel and insertion of the preprotein.

Amino Acid Sequence↗
PubMed1996

Sending and receiving the hedgehog signal: control by the Drosophila Gli protein Cubitus interruptus.

Drosophila limb development is organized by interactions between anterior and posterior compartment cells. Posterior cells continuously express and require engrailed (en) and secrete Hedgehog (Hh) protein. Anterior cells express the zinc-finger protein Cubitus interruptus (Ci). It is now shown that anterior cells lacking ci express hh and adopt posterior properties without expressing en. Increased levels of Ci can induce the expression of the Hh target gene decapentaplegic (dpp) in a Hh-independent manner. Thus, expression of Ci in anterior cells controls limb development (i) by restricting hh secretion to posterior cells and (ii) by conferring competence to respond to Hh by mediating the transduction of this signal.

Animals↗
PubMed1996

Creatine kinase and creatine kinase-MB release after nontraumatic cardiac arrest.

The aim of the study was to describe the course of serum creatine kinase (CK) and its MB fraction (CK-MB) in patients surviving cardiac arrest, and to identify factors influencing CK and CK-MB release. The study was set in the community of Vienna, Austria. Data concerning cardiopulmonary resuscitation, collected within a period of 33 months, were evaluated retrospectively and compared with laboratory blood investigations collected prospectively (on admission and after 6, 12, and 24 hours) in 107 adult patients surviving a witnessed cardiac arrest for 24 hours. CK and CK-MB were elevated in >75% of the patients within 24 hours. Release of CK and CK-MB was mainly associated with electrocardiographic evidence of acute myocardial infarction (AMI) cumulative energy administered during defibrillation, and duration of chest trauma by compression. The CK-MB/CK ratio was elevated in 32% of the patients. Of patients with electrocardiographic evidence of AMI, only 49% had an elevated CK-MB/CK ratio. In conclusion, the elevation in serum CK and CK-MB fraction in patients after nontraumatic cardiac arrest is a frequent finding, and is associated with ischemic myocardial injury, as well as physical trauma to the chest. This should be considered when interpreting the course of CK and CK-MB fraction for the diagnosis of AMI.

Adult↗
PubMed1996

Determinants in the presequence of cytochrome b2 for import into mitochondria and for proteolytic processing.

Determinants in a mitochondrial targeting signal for import and processing were analyzed by introducing deletions into the presequence of cytochrome b2. The matrix targeting signal and the signal recognized by the mitochondrial processing peptidase were found to be separate. The signal for import into the matrix is located at the N-terminus within a stretch of 20 amino acid residues that has the potential to form a positively charged, amphipathic alpha-helix. The mitochondrial processing peptidase cleaves after residue 31 and recognizes a short sequence motif around the scissile bond. In the context of a presequence, the cleavage site is accessible for the processing peptidase. At a different location or in a different context, the cleavage site motif is still specifically recognized but processed with lower efficiency. The matrix targeting signal may help to present the cleavage site motif to the mitochondrial processing peptidase.

Amino Acid Sequence↗
PubMed1996

Evaluation of 11 enzyme immunoassays for the detection of immunoglobulin M antibodies to Epstein-Barr virus.

Laboratory diagnosis of Epstein-Barr virus (EBV) infection is based mainly on serological tests. The analysis of the pattern of class-specific immunoglobulin response against defined viral antigens, i.e. virus capsid antigen (VCA), early antigen (EA) and Epstein-Barr nuclear antigen (EBNA), permits the differentiation between primary, latent and secondary (reactivated) EBV infection. In recent months, numerous test kits for the detection of VCA specific IgM antibody have been introduced on the international market. With a panel of well defined sera, the sensitivity and specificity of eleven different commercially available IgM ELISAs was evaluated. A well established, commercially available, indirect immunofluorescence assay (IFA) served as the reference test. Compared to the IFA, the Biotest and Sigma Diagnostic assays had the highest sensitivity for the detection of IgM antibody to VCA or EA. A variable number of false positive results (n = 0-9) was obtained with the EBV-IgM assays by testing potentially cross-reactive serum samples. Up to 19 serum samples from immunocompromised organ transplant recipients were found positive with the Sigma Diagnostics assay. The results of this study show that there are great differences in quality of current EBV-IgM-ELISA test kits. Depending on the clinical setting, it may be important to use a test kit which detects immunoglobulin M reactivity to EA in order to warrant an optimal sensitivity for the serological diagnosis of EBV reactivation in immunocompromised patients. However, since most immunosuppressed patients have serological reactivations, and in most cases these are asymptomatic, the clinical relevance of the detection of EA-IgM is very low.

Antibodies, Viral↗
PubMed1996

Feasibility of using a swine portal vein containing a metallic stent for creating a portacaval shunt.

RATIONALE AND OBJECTIVES: We evaluated the feasibility of using a metallic stented portal vein as a conduit for portacaval shunt in pigs. METHODS: A metallic self-expanding stent was placed in the portal vein of five pigs under combined ultrasound and fluoroscopic guidance via a percutaneous transhepatic approach. After 6 weeks, a portacaval shunt was performed using the stented portal vein as a conduit. A single angiogram followed immediately by sacrifice and histologic examination was performed on each pig at a varying time interval postshunt. RESULTS: One pig died 3 days after the shunt procedure because of a presumed surgical technical failure and a consequent thrombosed portal vein. Angiographic patency of the portacaval shunt was confirmed in the four remaining pigs. Postmortem histologic evaluation showed more complete endothelialization and subintimal organization in the more chronic stents. Thrombus occurred only in the stent of the pig that died. There was no significant luminal obstruction in the other four stents. CONCLUSION: Our results suggest that a stented portal vein can be used successfully as a conduit for portacaval shunt in pigs.

Angiography↗
PubMed1996

Preclinical management of thromboembolic disorders.

Preclinical management faces considerable diagnostic and therapeutic limitations. Patient history, physical examination, and few technical means (electrocardiogram [ECG], blood glucose measurement) must suffice to arrive at a suspected or definite diagnosis. Emergency treatment of most medical conditions inside the hospital differs from the preclinical setting. Critically ill patients must be transported to the hospital in emergency units with standardized equipment. Diagnosis of acute myocardial infarction relies on patient history, present symptoms, and a 12-lead ECG, and can be made with relative certainty. Therapeutic management focuses on reduction of myocardial oxygen consumption and optimizing oxygen availability. Monitoring for possible arrhythmias is essential. Few exceptional situations justify preclinical thrombolytic therapy. After a neurologic deficit has been diagnosed, the management of patients with stroke includes support of vital functions and admission to a hospital where computed tomography or magnetic resonance imaging is available. Pulmonary thromboembolism is frequently misdiagnosed even in the hospital. Preclinical physical examination, patient history, ECG, and pulse oximetry allow a positive diagnosis only in massive embolization. Anticoagulation with heparin is essential. If cardiopulmonary resuscitation is necessary, preclinical thrombolysis may be an option. Although deep vein thrombosis is difficult to recognize, classical symptoms of acute arterial occlusion are rarely missed. Treatment consists of general measures and anticoagulation.

Arterial Occlusive Diseases↗