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Biomedical subjects

M Brunner

Publications and source records attributed to M Brunner.

At least 19 recordsLinked to original sources
PubMed2002

Autologous blood stem cell transplantation in refractory systemic lupus erythematosus with severe pulmonary impairment: a case report.

For patients with severe forms of autoimmunity, including systemic lupus erythematosus (SLE), purging autoreactive T cells from the immune repertoire by transplanting autologous hematopoietic stem cells (ASCT) is a therapeutic option. We describe an 18-year-old woman with SLE who had been treated with corticosteroids, azathioprine, cyclophosphamide (CYC), and immunopheresis for 4 years, during which time mechanical ventilation for lupus pneumonitis had been repeatedly required. After the patient was conditioned by administration of CYC and antithymocyte globulin, a total of 8.87 x 10(6) purified CD34+ cells per kg of body weight was infused. Hematopoietic regeneration was observed within 9 days. Twenty-one months after ASCT, the patient continues to be in complete clinical remission, with no signs of SLE-related disease activity and without any immunosuppressive medications. Her pulmonary function has returned to normal. Although a longer followup is required for assessment of the durability of response, the patient's course indicates that ASCT may be a way to reinduce tolerance in patients with SLE.

Adolescent↗
PubMed2002

Activation-induced T cell death, and aberrant T cell activation via TNFR1 and CD95-CD95 ligand pathway in stable cardiac transplant recipients.

Specific blockade by antibodies (Abs) utilized in induction therapy may cause activation-induced cell death (AICD) in lymphocytes of transplant recipients, preactivated via CD95 and tumour necrosis factor-alpha receptor type 1 (TNFR1), and reduce allograft rejection frequency. Amongst 618 heart transplant (HTX) patients receiving antithymocytes globulin (ATG) therapy, 14 recipients with IVUS-verified freedom of transplant vasculopathy were studied. The control group contained 14 patients awaiting transplantation, classified by the New York Hearth Association heart failure as class IV. From 618 HTX patients 89% were free of rejection grade ISHLT > or =2-3 within 3-month post transplantation and 86% after one year. The death inducing receptors (DIR) such as CD95, CD95L and soluble TNFR1 were significantly increased in HTX recipients versus controls, as demonstrated by FACS, immunoblotting or ELISA (P < 0.001). The presence of increased DIR and in vivo apoptosis in HTX recipients, indicated by annexin-V binding, was further confirmed by the presence of high concentration of histones in the sera of patients. ATG, anti-IL-2R and OKT-3 Abs inhibited cell proliferation in a dose-dependent manner. The induction of apoptosis and/or necrosis was demonstrated in cells cultured with these Abs by annexin-V and 7-aminoactinomycin staining, respectively. Our findings demonstrate that T cells from HTX recipients express high level of CD95, CD95L and soluble TNFR1, and undergo apoptosis and AICD. These cells recognizing donor alloantigens may be selectively eliminated in vivo, and should be responsible for the observed immunological unresponsiveness, indicated by low rejection rates in our patient cohort treated by conventional triple therapy.

Adult↗
PubMed2001

A PEST-like element in FREQUENCY determines the length of the circadian period in Neurospora crassa.

FREQUENCY (FRQ) is a crucial element of the circadian clock in Neurospora crassa. In the course of a circadian day FRQ is successively phosphorylated and degraded. Here we report that two PEST-like elements in FRQ, PEST-1 and PEST-2, are phosphorylated in vitro by recombinant CK-1a and CK-1b, two newly identified Neurospora homologs of casein kinase 1 epsilon. CK-1a is localized in the cytosol and the nuclei of Neurospora and it is in a complex with FRQ in vivo. Deletion of PEST-1 results in hypophosphorylation of FRQ and causes significantly increased protein stability. A strain harboring the mutant frq Delta PEST-1 gene shows no rhythmic conidiation. Despite the lack of overt rhythmicity, frq Delta PEST-1 RNA and FRQ Delta PEST-1 protein are rhythmically expressed and oscillate in constant darkness with a circadian period of 28 h. Thus, by deletion of PEST-1 the circadian period is lengthened and overt rhythmicity is dissociated from molecular oscillations of clock components.

Amino Acid Sequence↗
PubMed2001

Application of the minimal trauma tissue biopsy to transdermal clinical pharmacokinetic studies.

Although the transdermal administration of drugs has gained considerable importance, reliable methods for the quantitative assessment of transdermal drug penetration are scarce. The aim of the present study was therefore to evaluate the scopes and limits of the minimal trauma tissue biopsy (MTTB) technique for the in vivo characterization of the transdermal penetration process and the assessment of dermal drug kinetics in humans following topical drug application. Nicotine TTS (21 mg/24 h) was administered transdermally to 13 healthy volunteers. Repeated minimally invasive dermal and subdermal tissue biopsies were obtained at defined time points from defined skin layers directly underlying the TTS. The position of the biopsy needle and depth of biopsate were determined by 2D ultrasound scanning. The biopsy procedure was well tolerated by all volunteers and up to six biopsies within a period of 10 h were easily accepted. Dermal pharmacokinetic profiles for nicotine were obtained in all experiments and corresponded well to the values measured in previous studies on transdermal nicotine penetration. Mean area under the nicotine concentration time curve (AUC) in subepidermal layers underneath the application site of the TTS was 70.0+/-55.1 microg/g per h. There was a correlation between the depth of biopsy sampling and dermal nicotine concentrations at steady state (r=0.7). The MTTB is a suitable, well tolerated technique for the detection of transdermally applied compounds in defined subepidermal tissue layers and could therefore become a valuable tool in the development and assessment of transdermal dosage forms.

Administration, Cutaneous↗
PubMed2001

Role of the deafness dystonia peptide 1 (DDP1) in import of human Tim23 into the inner membrane of mitochondria.

Tim8 and Tim13 of yeast belong to a family of evolutionary conserved zinc finger proteins that are organized in hetero-oligomeric complexes in the mitochondrial intermembrane space. Mutations in DDP1 (deafness dystonia peptide 1), the human homolog of Tim8, are associated with the Mohr-Tranebjaerg syndrome, a progressive neurodegenerative disorder. We show that DDP1 acts with human Tim13 in a complex in the intermembrane space. The DDP1.hTim13 complex is in direct contact with translocation intermediates of human Tim23 in mammalian mitochondria. The human DDP1.hTim13 complex complements the function of the TIM8.13 complex in yeast and facilitates import of yeast and human Tim23. Thus, the pathomechanism underlying the Mohr-Tranebjaerg syndrome may involve an impaired biogenesis of the human TIM23 complex causing severe pleiotropic mitochondrial dysfunction.

Animals↗
PubMed2001

Modular structure of the TIM23 preprotein translocase of mitochondria.

The TIM23 complex mediates import into mitochondria of nuclear encoded preproteins with a matrix-targeting signal. It is composed of the integral membrane proteins Tim17 and Tim23 and the peripheral membrane protein Tim44, which recruits mitochondrial Hsp70 to the sites of protein import. We have analyzed the functions of these constituents using a combined genetic and biochemical approach. Depletion of either Tim17 or Tim23 led to loss of import competence of mitochondria and to a reduction in the number of preprotein-conducting channels. Upon depletion of Tim44, mitochondria also lost their ability to import proteins but maintained normal numbers of import channels. In the absence of Tim44 precursor protein was specifically recognized. The presequence was translocated in a Delta psi-dependent manner across the inner membrane and cleaved by matrix-processing peptidase. However, the preprotein did not move further into the matrix but rather underwent retrograde sliding out of the TIM23 complex. Thus, the TIM23 complex is composed of functionally independent modules. Tim17 and Tim23 are necessary for initiating translocation, whereas Tim44 and mitochondrial Hsp70 are indispensable for complete transport of preproteins and for unfolding of folded domains of preproteins.

Carrier Proteins↗
PubMed2001

New method for detection of Borrelia burgdorferi antigen complexed to antibody in seronegative Lyme disease.

Serologic tests for Lyme disease are problematic. Because of cross-reactive antigens Borrelia burgdorferi (Bb) shares with other organisms, Lyme disease can be overdiagnosed. However, in addition to specificity problems, serologic tests for early Lyme disease can be falsely negative due to lack of sensitivity of ELISAs and Western blots. Most routine antibody tests are designed to detect free antibodies, and in early, active disease, circulating antibodies may not be free in serum but sequestered in complexes with the antigens which originally triggered their production. This difficulty may be overcome by first isolating immune complexes (IC) from the serum and using this fraction for testing. Free Borrelia-specific antibodies can then be liberated from the immune complexes which may enhance test sensitivity in patients with active disease. We developed a technique that captures the antibody component of IC on immunobeads, and subsequently releases the antigen component of IC. Immunoblotting with monoclonal antibody detected at least one antigen to be OspA, thus definitively demonstrating a Borrelia-specific antigen in circulating IC in early Lyme disease. This test is also useful in demonstrating Bb antigen in otherwise seronegative Lyme disease patients.

Antibodies, Bacterial↗
PubMed2001

Circadian regulation of the light input pathway in Neurospora crassa.

FREQUENCY (FRQ) is a critical element of the circadian system of Neurospora. The white collar genes are important both for light reception and circadian function. We show that the responsiveness of the light input pathway is circadianly regulated. This circadian modulation extends to light-inducible components and functions that are not rhythmic themselves in constant conditions. FRQ interacts genetically and physically with WHITE COLLAR-1, and physically with WHITE COLLAR-2. These findings begin to address how components of the circadian system interact with basic cellular functions, in this case with sensory transduction.

Circadian Rhythm↗
PubMed2001

Phase behavior of two-dimensional colloidal systems in the presence of periodic light fields.

We investigate the phase behavior of a two-dimensional suspension of charge stabilized polystyrene spheres in the presence of a one-dimensional periodic light field. With increasing light intensity we observe a liquid-solid followed by a solid-liquid transition which are known as laser-induced freezing and melting, respectively. Here we report on measurements where, in addition to the light intensity, the single particle density was also systematically varied. As a result, we obtain for the first time the full thermodynamic information about the system which allows comparison with numerical predictions of other authors.

Journal Article↗
PubMed2001

Clusters of life-threatening ventricular arrhythmias in patients with implanted cardioverter-defibrillators: prevalence, characteristics, and risk stratification.

BACKGROUND: Series of discharges from an implanted defibrillator (ICD) to terminate life-threatening ventricular tachyarrhythmias are one particular aspect of energy use and success of ICD therapy. Little is known about prevalence. characteristics, and risk stratification of so-called "cluster arrhythmias." HYPOTHESIS: The objective of this study was to examine the frequency of cluster arrhythmias, to characterize the temporal relationship precisely, and to assess the accompanying circumstances of their occurrence, whereby risk stratification was to be made if appropriate. METHODS: In all, 63 consecutive patients were followed prospectively over 727 +/- 684 days to determine the presence and characteristics of cluster arrhythmias (45,801 patient days). In 30 patients, 374 ICD episodes of ventricular tachyarrhythmias were analyzed for their temporal relationship. After a first successfully terminated ventricular tachyarrhythmia, further ICD discharges within 3 h were observed during 145 of 374 (39%) episodes; mean time interval between these arrhythmias was 25 +/- 32 min. RESULTS: Arrhythmia clusters occurred in 19 of 30 (63%) patients. In multivariate analysis, only underlying heart disease was predictive for accumulation of ventricular tachyarrhythmias. Cluster arrhythmias were more frequent among patients with ischemic heart disease than among those with nonischemic heart disease (40.0 vs. 29.2%, p < 0.05). Ejection fraction, age, gender, and other parameters were not predictive for occurrence of arrhythmia clusters. In 4 of 19 patients, accumulation of ICD discharges was predictive for new onset of myocardial ischemia elicited by exercise test. CONCLUSIONS: Cluster arrhythmias are most common in patients with ICDs with coronary heart disease and may indicate disease progression and increasing instability, for example, due to new onset of myocardial ischemia.

Adult↗
PubMed2001

[Retrograde venous perfusion (RVP in ulcero-mutilating neuropathy].

The ulcero-mutilating neuropathy is defined by the triad of painless ulcers of the feet, sensitive polyneuropathy of the lower legs and osteolysis in the forefoot area. The condition mainly affects middle-aged men suffering from diabetes mellitus, liver diseases, alcoholism, obesity and constitutional foot deformities. Systemic venous infusions of appropriate antibiotics can hardly reach effective target tissue levels because of the damaged microcirculation. Thus we used retrograde venous perfusion (RVP) of several drugs into the injured leg during short time blockade of arterial blood supply and achieved better therapeutic effects. Applying the RVP route, a solution containing 200 mg netilmycin, 120 mg gentamycin, 50 mg buflomedil, 2500 IU heparin and 4 mg dexamethasone in 100 ml 0.9% saline was injected as bolus into a dorsal foot vein and the blood supply was blocked for 20 minutes. The RVP was carried out daily over a period of 7 to 10 days. We treated 7 patients suffering from a ulcero-mutilating neuropathy with the RVP. Over an observation period of up to four weeks, in one patient the plantar ulcers healed completely, while in the other six cases the RVP lead to a regression of inflammatory signs and a reduction of ulcer size of up to 50 per cent.

Alcoholism↗
PubMed2001

Regulation of cyclosporin A sensitive mitochondrial permeability transition by the redox state of pyridine nucleotides.

The mechanisms involved in the induction of cyclosporine A sensitive mitochondrial swelling by oxidative stress were investigated in isolated guinea pig liver mitochondria. The aim of our study was to investigate, if swelling is inevitably associated with the oxidation of pyridine nucleotides, and if the oxidized pyridine nucleotides have to be hydrolysed for the induction of mitochondrial swelling. Quantitative measurement of oxidized pyridine nucleotides was performed with HPLC. Mitochondrial swelling was recorded by monitoring the decrease in light scattering of the mitochondrial suspension. Reduction and oxidation of pyridine nucleotides were followed by monitoring the changes of the autofluorescence signal of reduced pyridine nucleotides. Qualitative measurement of mitochondrial membrane potential was performed with the fluorescence indicator rhodamine 123. Neither t-butyl hydroperoxide nor the dissipation of the mitochondrial inner membrane potential with FCCP (carbonyl cyanide-p-trifluoromethoxyphenyl hydrazone) induced the opening of the membrane permeability transition pore, unless an extensive oxidation of mitochondrial pyridine nucleotides took place. Mitochondrial swelling induced by our experimental conditions was always sensitive to cyclosporine A and accompanied by a cyclosporine A sensitive release of inner mitochondrial pyridine nucleotides without pyridine nucleotide hydrolysis. Not the cycling of calcium across the mitochondrial inner membrane but the accumulation of calcium inside the mitochondria was a prerequisite for mitochondrial swelling. The mitochondrial membrane permeability transition is neither caused nor accompanied by the hydrolysis of mitochondrial pyridine nucleotides.

Animals↗
PubMed2001

Soft tissue concentrations of ciprofloxacin in obese and lean subjects following weight-adjusted dosing.

OBJECTIVE: To investigate whether weight adjusted ciprofloxacin dosing results in comparable target site concentrations in obese and lean subjects. DESIGN: Comparative study in two populations. SUBJECTS: Twelve obese subjects (mean weight 122+/-22.6 kg, 28-52 y, male&ratio;female ratio 4&ratio;8) and 12 age- and sex-matched lean controls (mean weight 59+/-8.6 kg). METHODS: Sampling of interstitial space fluid by means of calibrated in vivo microdialysis after a weight-adjusted intravenous bolus dose of 2.85 mg/kg ciprofloxacin. Analysis of drug concentration by high pressure liquid chromatography. RESULTS: We found significantly higher peak and trough levels of ciprofloxacin in plasma for obese subjects (9.97+/-5.64 and 0.44+/-0.10 microg/ml vs 2.59+/-1.06 and 0.19+/-0.09 microg/ml in lean subjects, P<0.05), while concentration-time curves of interstitial fluid of muscle and subcutaneous fat did not differ between the groups. Tissue penetration, expressed as AUC(tissue)/AUC(plasma) ratio was significantly lower in obese subjects (0.45+/-0.27 vs 0.82+/-0.36, P<0.01). CONCLUSION: We conclude that the penetration process into the interstitial space fluid is impaired in obese subjects. Therefore antibiotic doses need not be adjusted for an increase in fat/water ratio. Weight-adjusted dosing based on actual body weight will yield adequate tissue levels for ciprofloxacin.

Adult↗
PubMed2001

Differential activation of cytokine secretion in primary human colonic fibroblast/myofibroblast cultures.

BACKGROUND: Fibroblasts and myofibroblasts are known to secrete a wide spectrum of cytokines, but the individual spectrum is tissue-specific. We investigated the effect of cell activation on cytokine secretion of isolated human colonic fibroblasts/myofibroblasts from control patients and patients with mucosal inflammation. METHODS: Primary cultures of human colonic submucosal fibroblasts/myofibroblasts were incubated with IL-1alpha (100 U/ml), IL-Ibeta (10 ng/ml), IL-10 (10 ng/ml), TNF (10 ng/ml), PMA (10 ng/ml), LPS (50 ng/ml), IL-4 (10 ng/ml), or a combination of IL-1 and TNF. Secreted cytokines were determined by ELISA. NF-kappaB activation was demonstrated by electrophoretic mobility-shift assays (EMSA). RESULTS: Incubation of colonic fibroblasts/myofibroblasts with IL-1, LPS, TNF and PMA induced secretion of IL-6, IL-8, M-CSF and GM-CSF. IL-8 and IL-6 secretion could be stimulated by IL-1alpha, IL-1beta, TNF, PMA and LPS within 6 h of incubation. IL-6 secretion was stimulated from 0.5 +/- 0.01 pg/h x microg fibroblast protein to 18.5 +/- 2.6 pg/h x microg fibroblast protein with IL-1beta (P < 0.01). IL-8 secretion was stimulated from 1.0 +/- 0.1 pg/h x microg fibroblast protein to 41.1 +/- 3.6 pg/h x microg (P < 0.005). IL-4 and IL-10 did not change cytokine secretion significantly. No significant differences between cultures from normal and inflamed mucosa were observed. TNF and IL-1 induced NF-kappaB activation. ALLN, a proteasome and NF-kappaB activation inhibitor, reduced TNF-mediated IL-8, GM-CSF and M-CSF induction significantly, whereas induction of IL-6 secretion remained unchanged. CONCLUSION: Human colonic myofibroblasts can secrete large amounts of IL-6, IL-8, M-CSF and GM-CSF upon stimulation. The induction of IL-8, M-CSF and GM-CSF, but not of IL-6 secretion, is mediated mainly by NF-kappaB activation. The cytokine profile and the total amounts of cytokines released suggest that colonic myofibroblasts can play a role in leukocyte recruitment and during mucosal inflammation. They therefore have to be regarded as an important part of the mucosal immune system.

Adult↗
PubMed2001

Impaired target site penetration of beta-lactams may account for therapeutic failure in patients with septic shock.

OBJECTIVE: Current guidelines for adjusting antimicrobial therapy regimens commonly are based on drug concentrations measured in plasma. In septic patients, however, the interstitial space of soft tissues in addition to the central compartment represents the target site of infection. We thus hypothesized that one explanation for therapeutic failure during antibiotic treatment might be the inability to achieve effective antimicrobial concentrations in the interstitial space fluid of soft tissues. This is corroborated by the fact that piperacillin, a frequently administered beta-lactam antibiotic, often fails to be effective despite documented susceptibility of the causative pathogen in vitro. DESIGN: Prospective comparative study of two groups. SETTING: The intensive care unit and research ward of an university hospital. SUBJECTS: Six patients with septic shock and a control group of six gender- and age-matched healthy volunteers. INTERVENTIONS: To measure piperacillin penetration into the interstitial space fluid of skeletal muscle and subcutaneous adipose tissue, we employed microdialysis after a single intravenous administration of 4.0 g of piperacillin to patients and healthy volunteers. Piperacillin concentrations were assayed by using reversed-phase high-pressure liquid chromatography. MEASUREMENTS AND MAIN RESULTS: In septic shock patients, interstitial piperacillin concentrations in skeletal muscle and subcutaneous adipose tissue were five- to ten-fold lower than corresponding free plasma concentrations (p <.03). Mean piperacillin concentrations in subcutaneous adipose tissue never exceeded 11 microg/mL, which is below the minimal inhibitory concentration for a range of relevant pathogens in patients with septic shock. CONCLUSION: The results of the present study demonstrate that in septic shock patients, piperacillin concentrations in the interstitial space may be subinhibitory, even though effective concentrations are attained in plasma. The lack of success of antimicrobial therapy in these patients thus might be attributable to inadequate target site penetration of antibiotics.

Adipose Tissue↗
PubMed2001

Use of serum immune complexes in a new test that accurately confirms early Lyme disease and active infection with Borrelia burgdorferi.

The present recommendation for serologic confirmation of Lyme disease (LD) calls for immunoblotting in support of positive or equivocal ELISA. Borrelia burgdorferi releases large quantities of proteins, suggesting that specific antibodies in serum might be trapped in immune complexes (ICs), rendering the antibodies undetectable by standard assays using unmodified serum. Production of ICs requires ongoing antigen production, so persistence of IC might be a marker of ongoing or persisting infection. We developed an immunoglobulin M (IgM) capture assay (EMIBA) measuring IC-derived IgM antibodies and tested it using three well-defined LD populations (from an academic LD referral center, a well-described Centers for Disease Control and Prevention (CDC) serum bank, and a group of erythema migrans patients from whose skin lesions B. burgdorferi was grown) and controls (non-Lyme arthritis inflammatory joint disease, syphilis, multiple sclerosis, and nondisease subjects from a region where LD is endemic, perhaps the most relevant comparison group of all). Previous studies demonstrated that specific antigen-antibody complexes in the sera of patients with LD could be precipitated by polyethylene glycol and could then be disrupted with maintenance of the immunoreactivity of the released antibodies, that specific anti-B. burgdorferi IgM was concentrated in ICs, and that occasionally IgM to specific B. burgdorferi antigens was found in the IC but not in unprocessed serum. EMIBA compared favorably with commercial and CDC flagellin-enhanced enzyme-linked immunosorbent assays and other assays in confirming the diagnosis of LD. EMIBA confirmed early B. burgdorferi infection more accurately than the comparator assays. In addition, EMIBA more accurately differentiated seropositivity in patients with active ongoing infection from seroreactivity persisting long after clinically successful antibiotic therapy; i.e., EMIBA identified seroreactivity indicating a clinical circumstance requiring antibiotic therapy. Thus, EMIBA is a promising new assay for accurate serologic confirmation of early and/or active LD.

Antibodies, Bacterial↗
PubMed2001

Characterization of mice with a combined suppression of I(to) and I(K,slow).

Cardiac-specific expression of a truncated Kv1.1 polypeptide (Kv1DN) attenuates the slow inactivating outward K(+) current (I(K,slow)), increases action potential duration (APD) and Q-T intervals, and induces spontaneous ventricular arrhythmias. Expression of the pore mutant of Kv4.2 (Kv4DN) eliminates the fast component of the transient outward current (I(to)) and prolongs APDs and Q-T intervals markedly; however, no arrhythmias are seen in Kv4DN mice, suggesting that APD and Q-T prolongation are not per se proarrhythmic. To test this hypothesis, the Kv1DN and Kv4DN lines were crossbred to produce animals (Kv1/Kv4DN) expressing both transgenes in an identical genetic background. Whole cell voltage-clamp recordings from left ventricular apex cells confirmed that in Kv1/Kv4DN left ventricular apex cells, both components (fast and slow) of I(to) and the 4-aminopyridine-sensitive component of I(K,slow) are eliminated, resulting in marked APD prolongation compared with wild-type, Kv1DN, or Kv4DN cells. Telemetric electrocardiogram monitoring (n = 10 mice/group) revealed a significant prolongation of Q-Tc and P-R intervals in Kv1/Kv4DN animals compared with Kv1DN or Kv4DN animals. Spontaneous arrhythmias were observed mainly in Kv1DN mice. Thus the attenuation of fast I(to) in addition to I(K,slow) in Kv1/Kv4DN mice causes significant prolongation of APD and Q-T intervals and attenuation of spontaneous arrhythmias.

4-Aminopyridine↗