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Biomedical subjects

K Wolf

Publications and source records attributed to K Wolf.

At least 19 recordsLinked to original sources
PubMed2006

Treatment of Chlamydia trachomatis with a small molecule inhibitor of the Yersinia type III secretion system disrupts progression of the chlamydial developmental cycle.

The obligate intracellular bacterium Chlamydia trachomatis possesses a biphasic developmental cycle that is manifested by differentiation of infectious, metabolically inert elementary bodies (EBs) to larger, metabolically active reticulate bodies (RBs). The cycle is completed by asynchronous differentiation of dividing RBs back to a population of dormant EBs that can initiate further rounds of infection upon lysis of the host cell. Chlamydiae express a type III secretion system (T3SS) that is presumably employed to establish and maintain the permissive intracellular niche by secretion of anti-host proteins. We hypothesize that T3SS activity is essential for chlamydial development and pathogenesis. However, the lack of a genetic system has confounded efforts to establish any role of the T3SS. We therefore employed the small molecule Yersinia T3SS inhibitor N'-(3,5-dibromo-2-hydroxybenzylidene)-4-nitrobenzohydrazide, designated compound 1 (C1), to examine the interdependence of the chlamydial T3SS and development. C1 treatment inhibited C. trachomatis but not T4SS-expressing Coxiella burnetii development in a dose-dependent manner. Although chlamydiae remained viable and metabolically active, they failed to divide significantly and RB to EB differentiation was inhibited. These effects occurred in the absence of host cell cytotoxicity and were reversible by washing out C1. We further demonstrate that secretion of T3S substrates is perturbed in C1-treated chlamydial cultures. We have therefore provided evidence that C1 can inhibit C. trachomatis development and T3SS activity and present a model in which progression of the C. trachomatis developmental cycle requires a fully functional T3SS.

Bacterial Proteins↗
PubMed2005

[Identification of possible cognizance parameters of "mimic disintegration" in schizophrenia using facial electromyography].

UNLABELLED: The aim of this study was to identify signs of "mimic disintegration" in schizophrenics using a facial electromyographic (EMG) method. We compared a group of 20 unmedicated schizophrenics with a group of 20 healthy subjects, measuring the activity of three joy-relevant facial muscles (zygomaticus major, orbicularis oculi, levator labii superioris) and two nonjoy-relevant facial muscles (frontalis, corrugator supercilii) as control muscles during two consecutive presentations of an erotic slide from the International Affective Picture System. RESULT: Schizophrenics show significantly less activity of joy-relevant facial muscles and a lower smile frequency than healthy subjects. Two signs of mimic disintegration" could be identified: 1. undefined mimic reactions and 2. lack of mimic consistency. CONCLUSION: Facial EMG is a state-of-the-art method for analyzing possible signs of mimic disintegration as described by Heimann and Spoerri. We suggest further examination of the two mimic disintegration signs regarding other emotions, necessarily including more facial muscles in the testing.

Adult↗
PubMed2004

[Role of bronchial epithelial cells in chronic obstructive pulmonary disease].

Chronic obstructive pulmonary disease (COPD) is characterized by increased numbers of neutrophils in the airway lumen and increased infiltration of CD8 positive T lymphocytes both in the airways and in the lung parenchyma. However, the underlying reasons for these changes have not been fully investigated. Differences in bronchoepithelial activation in COPD patients may contribute to COPD pathophysiology since the bronchial epithelium does not act as a passive barrier but has the potential to orchestrate local inflammatory reactions by releasing a variety of inflammatory mediators. The expressions of several CXC and CC chemokines were studied in primary bronchial epithelial cells derived from COPD patients and smokers without airflow limitation. In addition, cDNA array technology was used to investigate the differential bronchoepithelial expression of cytokine and cytokine-related genes in COPD patients and lifelong non-smokers without airflow obstruction. Bronchial epithelial cells from COPD patients are characterized by increased expressions of CXC chemokines but not CC chemokines. In addition, CD 146 was identified as a new adhesion molecule showing significant upregulation in primary bronchial epithelial cells derived from COPD patients, on both the steady-state mRNA and protein level. These results suggest that the bronchial epithelium plays an important role in COPD pathophysiology.

Adult↗
PubMed2004

Quantitative gene expression analysis of fractalkine using laser microdissection in biopsies from kidney allografts with acute rejection.

Percutaneous biopsy of the kidney remains the gold standard to establish a diagnosis in renal diseases. Only semiquantitative assessments of gene expression on biopsies have been possible so far. We studied gene expression of the chemokine fractalkine (FKN) in 12 biopsies from laser microdissected kidney allografts that showed histologic signs of acute rejection and 10 controls. As quantified by real-time PCR, the relative tubular FKN expression increased from 1.0 [0.81 to 2.95] (median [range]) in controls to 12.44 [0.90 to 191.0] in acute rejection (P < .01); glomerular FKN expression from 1.3 [0.07 to 27.44] to 12.22 [1.32 to 50.23] (P < .05); and vascular expression, from 0.72 [0.37 to 5.11] to 7.07 [1.19 to 73.49] (P < .01). Furthermore, there was a trend toward higher glomerular FKN expression among patients with more severe rejection. Our results suggest a role of FKN in acute renal allograft rejection.

Acute Disease↗
PubMed2004

Sodium transport across the isolated epithelium of sheep omasum is influenced by luminal ammonia.

Ammonia is a physiological fermentation product in the forestomachs and is absorbed from the rumen and omasum. Cellular uptake of ammonia affects the intracellular pH of polar and non-polar cells. The effect of the uptake on the pH of the cytosol depends on the predominant form of ammonia. NH(3) uptake and its intracellular protonation tend to alkalinize the cytoplasm, whereas the uptake of NH(4)(+) acidifies the cytoplasm by reversing this reaction. Consequently, the absorption of ammonia across the omasal epithelium could cause a change of the intracellular pH and pH-dependent transport mechanisms like Na/H exchange. Because no information is available about the form of ammonia absorbed in the omasum and, hence, possible modulation of Na transport by ammonia, the effect of increasing luminal ammonia concentrations (0, 5, 15 and 30 mmol/l) on Na transport were studied. In epithelia of hay-fed animals, ammonia linearly inhibited Na transport in a dose-dependent manner, at a luminal pH of 7.40, but not at a pH of 6.40. Ammonia did not influence Na transport in epithelia of concentrate-fed animals. Because luminal ammonia did not consistently change the short circuit current or tissue conductance absorption of ammonia as NH(4)(+) appears to be unlikely. The predominant form of ammonia absorbed in the omasum is probably NH(3), which is protonated in the cytosol. The reduced availability of protons may be the cause of inhibition of Na transport via Na/H exchange.

Ammonia↗
PubMed2003

Development of a bisphenol A-adsorbing yeast by surface display of the Kluyveromyces yellow enzyme on Pichia pastoris.

A novel surface-engineered strain of yeast Pichia pastoris was constructed that displays at its surface Kluyveromyces lactis Yellow Enzyme (KYE) fused to the C-terminal half of Saccharomyces cerevisiae alpha-agglutinin. The expression of the fusion protein was controlled by the AOX1-promoter. The new strain showed an increased sorption of the xenoestrogen Bisphenol A (BPA). It was shown that sorption of BPA depended on the presence of methanol in the growth medium and on the pH of the binding assays. The binding kinetics were typical for binding at a surface. The present results demonstrate that the alpha-agglutinin surface display system can be used in the yeast P. pastoris.

Adsorption↗
PubMed2003

The effect of short chain fatty acids on calcium flux rates across isolated rumen epithelium of hay-fed and concentrate-fed sheep.

The present in vitro experiment was conducted to study the effect of two concentrations of short chain fatty acids [SCFA: 0 (control), 40 and 100 mmol/l in the buffer solution on mucosal side] on calcium ion (Ca2+) transport across the isolated rumen epithelium of two groups of sheep. One group was subjected to hay ad libitum, whereas the other to concentrate feed (800 g per day in equal portion at 7.00 and 15.00 hours and hay ad lib). The conventional Ussing chamber method was used for measuring the Ca2+ transport rates (45Ca), short-circuit current (Isc) and tissue conductance (GT) of isolated rumen epithelium. The SCFA significantly increased Isc of the epithelia of concentrate-fed sheep. In both hay- and concentrate-fed animals, 45Ca flux rates showed an almost linear increase in net flux rate () with rising concentrations of SCFA, as a result of a combined effect of a large increase in mucosal-to-serosal flux rates () and an almost linear, but small, decrease in serosal-to-mucosal flux rate (). In concentrate-fed sheep and were significantly higher in tissues incubated with SCFA compared with hay-fed animals. The well-known adaptable morphological and functional changes in the rumen epithelium attributable to concentrate feeding obviously include Ca2+ transport; such feeding therefore may be considered as a possible prophylactic measure in the prevention of milk fever.

Adaptation, Physiological↗
PubMed2003

Modulation of Na+ transport across isolated rumen epithelium by short-chain fatty acids in hay- and concentrate-fed sheep.

The effect of increasing concentrations of short-chain fatty acids [SCFA; mixture of the Na+ salts of acetic acid (62.5%), propionic acid (25.0%) and of butyric acid (12.5%)] on Na+ transport of sheep rumen epithelium was studied in vitro. The conventional Ussing chamber method was used for measuring Na+ transport rates (22Na+), short-circuit current (Isc) and tissue conductance (GT) of isolated rumen epithelium. SCFA in the buffer solution on the mucosal side caused a linear increase of Jnet Na+ from 1.14, to 1.22, 1.78 and 2.50 microeq/cm2/h in hay-fed sheep at 0, 15, 40 and 80 mmol/l SCFA, respectively. In a second study, the effect of higher SCFA concentrations [0 (control), 80, 100 and 120 mmol/l] was investigated with epithelia from two groups of sheep. One group was subjected to hay ad libitum, whereas the other received concentrate feed (800 g/day in equal portions at 7.00 am and 3.00 pm) and hay ad libitum. Epithelia from concentrate-fed sheep again showed a significant (p < 0.05) and linear increase in Jnet Na+ at 80, 100 and 120 mmol/l. However, in hay-fed sheep, the difference in increase among 80, 100 and 120 mmol/l SCFA was not significant, indicating that, above 80 mmol/l SCFA Jms and Jnet exhibit saturation. Moreover, Na+ fluxes (Jms and Jnet) were generally higher in concentrate-fed than in hay-fed sheep at all SCFA concentrations and significant differences were observed at 100 and 120 mmol/l SCFA. The obtained results confirm the effect of SCFA on Na+ transport and are in agreement with studies regarding feeding regimes and electrolyte transport in the rumen. The important new observation is the increase of Na+ transport in concentrate-fed sheep even at high concentrations of SCFA (100 and 120 mmol/l). The enhanced activity of the Na+/H+ exchanger at these SCFA concentrations supports the assumption that the capacity for regulating the intracellular pH by extrusion of protons is increased, suggesting an adaptation in concentrate-fed sheep. This adaptation could prevent possible disturbances of epithelial functions (transport and barrier) under conditions of increased SCFA absorption.

Absorption↗
PubMed2003

Upregulation of MCAM in primary bronchial epithelial cells from patients with COPD.

An increasing body of evidence indicates that the bronchial epithelium plays a crucial role in the pathophysiology of chronic obstructive pulmonary disease (COPD). The aim of this study was to identify new genes whose bronchoepithelial expression is specifically altered in COPD patients. Primary bronchial epithelial cell (PBEC) cultures were established from exsmokers with stable airflow limitation and never smokers. Complementary deoxyribonucleic acid array technology was used to investigate the differential expression of 847 cytokine and cytokine-related genes between the two groups. Statistical analysis was performed by means of significance analysis of microarrays and Bonferroni-corrected analysis of variance on ranks. Discriminant analysis and light cycler measurements as well as flow cytometry and Western blotting were used to confirm the significance of the array results at both the messenger ribonucleic acid (mRNA) and protein expression levels. With respect to array experiments, melanoma cell adhesion molecule (MCAM) was identified as the sole gene showing highly significant upregulation in PBECs from COPD patients compared to never smokers. Light cycler measurements confirmed these results, revealing a 2.9-fold and 2.0-fold increase in MCAM mRNA expression in COPD patients compared to nonsmokers and smokers, respectively. In addition, these differences are associated with higher median protein expression levels. These results strongly suggest involvement of melanoma cell adhesion molecule in the pathophysiology of the chronic airway inflammation seen in patients with chronic obstructive pulmonary disease.

Antigens, CD↗
PubMed2002

Disappearance of an intracerebral arteriovenous malformation in an HIV-infected patient after initiation of HAART.

HIV infection or complications of HIV-induced immunodeficiency may affect the central nervous system (CNS). However, vascular cerebral pathologies are very rare, in particular intracerebral arteriovenous malformations (AVM). We report the case of an HIV-infected patient who had a cerebral AVM leading to symptoms such as recurring focal seizures. Only after initiation of potent antiretroviral combination therapy, but not antiretroviral monotherapy or bitherapy, could the viral load be suppressed and immunodeficiency resolved. Two years after the start of highly active antiretroviraL therapy (HAART) total occlusion of the AVM could be demonstrated. Taken together, this case report may demonstrate the potent angiogenic activity of HIV for AVM. Also, this case report might show that inhibition of such a cofactor may lead to resolution of an AVM.

Antiretroviral Therapy, Highly Active↗
PubMed2002

Involvement of plasma atrial natriuretic peptide in protracted alcohol withdrawal.

OBJECTIVE: Atrial natriuretic peptide (ANP) has been shown to inhibit the effects of corticotrophin releasing hormone, corticotrophin and cortisol, and to influence affective and anxiety symptoms in man. We tested the hypothesis of whether ANP is associated with endocrine and psychopathological disturbances during acute alcohol withdrawal. METHOD: ANP and cortisol plasma concentrations were studied in alcoholics during in-patient detoxification and in healthy controls. Additionally, craving, depressive mood and anxiety were assessed. RESULTS: Although mean ANP levels increased significantly in alcoholics between days 1 and 14, they remained diminished compared to controls. Separating a subgroup of alcoholics with a decrease of ANP levels during withdrawal, these individuals revealed significantly elevated scores for mean and maximum craving and a trend to an elevated self-rated anxiety on day 14. CONCLUSION: We suggest that a dysregulation of ANP plasma levels during alcohol withdrawal may contribute to symptoms of protracted withdrawal such as craving and anxiety.

Adult↗
PubMed2002

Differences in LPS-induced activation of bronchial epithelial cells (BEAS-2B) and type II-like pneumocytes (A-549).

Lipopolysaccharide (LPS) as a major component of the outer membrane of gram-negative bacteria stimulates various cells to initiate a signalling cascade which ultimately leads to cell activation and expression of immunoregulatory or inflammatory cytokines. The human respiratory epithelium is an important environmental interface, but differences in LPS-induced cell activation between bronchial and alveolar epithelial cells have not yet been investigated in detail. First, the expression of Toll-like receptors (TLRs), as pattern-recognition receptors, was investigated for the bronchial epithelial cells and type II-like pneumocytes, demonstrating that they fulfil the prerequisites for LPS signalling. Thereafter, the effects of LPS, soluble CD14 (sCD14) and LPS-binding protein (LBP) on the release of interleukin-6 (IL-6) and IL-8 were studied. In the presence of LPS, sCD14 induced a significant and concentration-dependent cytokine release in type II-like pneumocytes, whereas the response of bronchial epithelial cells to sCD14 stimulation was low, implicating sCD14-independent activation mechanisms. Furthermore, LBP revealed inhibitory effects on the activation of alveolar epithelial cells, which may represent a novel local defence mechanism during gram-negative infection. We conclude that distinct pathways exist for LPS-induced activation of bronchial and alveolar epithelial cells.

Acute-Phase Proteins↗
PubMed2002

Tumour necrosis factor-alpha induced CD70 and interleukin-7R mRNA expression in BEAS-2B cells.

Over the past few years, evidence has emerged for the potential role of the human bronchial epithelial cell in the initiation and progress of inflammation of the airway. Thus, the aim of this study was to investigate the expression pattern of cytokines and immunomodulatory factors in the human bronchial epithelial cell. To elucidate this highly complex expression and regulation pattern, the simian virus-40 transformed human bronchial-epithelial cell line BEAS-2B was stimulated with human recombinant tumour necrosis factor (hrTNF)-alpha (10 ng x mL(-1) (specific activity, 2.86 x 10(7) U x mg(-1))) and messenger ribonucleic acid (mRNA) expression pattern was analysed by complementary deoxyribonucleic acid (cDNA) array analysis. Among 375 arrayed cDNA clones, 173 (46%) were detected in BEAS-2B cells. The levels of expression of 17 genes, including those of monocyte chemoattractant protein (MCP)-1, intercellular adhesion molecule (ICAM)-1, growth-related oncogene (GRO) alpha, beta, gamma, interleukin (IL)-7 receptor, CD70, IL-6, IL-8, granulocyte-macrophage colony-stimulating factor (GM-CSF) and regulated in activation, normal T-cell expressed and secreted (RANTES) were elevated after TNF-alpha stimulation. The differential character of 12 clones was further characterised and verified by real time polymerase chain reaction (PCR) analysis of total ribonucleic acid (RNA) isolated from BEAS-2B cells after 4 or 16 h incubation with increasing TNF-alpha concentrations (1 pg-10 ng x mL(-1)). The authors semiquantified concentration-dependent mRNA upregulation of cytokines and immunology factors identified in the array and could determine threshold values of mRNA increases at 10 pg x mL(-1)-1 ng x mL(-1) TNF-alpha by real-time PCR. For CD70 (CD27 ligand) and interleukin-7 receptor, which to the best of the author's knowledge have not yet been described in the human bronchial epithelial cell, a rapid and continuous messenger ribonucleic acid increase induced by 100 pg x mL(-1) tumour necrosis factor-alpha after only 60-90 min was shown. A potential role for these genes in the inflammatory process in the human bronchial epithelial cell is proposed.

Antigens, CD↗
PubMed2001

Dielectric spectroscopy of Schizosaccharomyces pombe using electrorotation and electroorientation.

Two complementary AC electrokinetic techniques electrorotation (ER) and electroorientation (EO) enabled the dielectric characterization of the rod-shaped fission yeast Schizosaccharomyces pombe. The use of microstructured electrodes allowed both ER and EO measurements to be performed over wide ranges of field frequency and medium conductivity. Due to their layered structure, living S. pombe cells exhibited up to three well resolved peaks in their ER spectra and also two distinct orientations, i.e., parallel or perpendicular to the imposed linear field. Heat treatment and enzymatic protoplast isolation led to dramatic changes in the electrokinetic behavior of fission yeast. Application of the theoretical models linking the ER and EO spectra yielded the dielectric parameters of the major structural units of S. pombe cells (cell wall, plasma membrane and cytosol). The dielectric characterization of yeasts has an enormous impact in biotechnology and biomedicine, because electric field pulse techniques (electrofusion and electropermeabilization) are widely used for production of transgenic yeast strains of economic importance. The present study also showed that combined ER and EO measurements can be employed as a powerful diagnostic tool for analyzing changes in yeast structure and physiology upon exposure to various stress conditions.

Electric Conductivity↗
PubMed2001

[Anemia, neutropenia and thrombocytopenia: hematological findings and HIV].

Hematologic pathologies like anemia, neutropenia and thrombocytopenia are frequently seen in HIV-infected patients. Etiologies of cytopenias are diverse, affect all three cell lines and cause considerable and sometimes even live threatening clinical problems. Opportunistic infections may cause bone marrow suppression or specific cytopenias but also adverse events of antiretroviral drugs and drugs against opportunistic infections frequently cause marrow suppression. Morphological changes in the bone marrow of HIV-infected patients are generally unspecific. Frequently, dysplasia, dyserythropoesis, lymphocyte infiltration or plasmocytosis are seen. In the following article, relevant practical points of pathogenesis and therapy options should be discussed with three case studies.

Adult↗