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Biomedical subjects

J Bauer

Publications and source records attributed to J Bauer.

At least 181 records · Page 10Linked to original sources

Stability of insertion sequence IS1245, a marker for differentiation of Mycobacterium avium strains.

Recently a novel insertion element, IS1245, has been described and suggested for use as a probe in restriction fragment length polymorphism studies of Mycobacterium avium strains. An important issue in this context is the stability of the insertion element. We analyzed single colonies of M. avium cultures and found frequent small one- to two-band changes. However, following repeated in vitro passages over 1 year, similar one- to two-band changes were observed in the IS1245 patterns of only six M. avium strains investigated.

AIDS-Related Opportunistic Infections↗

Typing of clinical Mycobacterium avium complex strains cultured during a 2-year period in Denmark by using IS1245.

In the present study restriction fragment length polymorphism analyses with the recently described insertion sequence IS1245 as a probe was performed with clinical Mycobacterium avium complex strains cultured in Denmark during a 2-year period. The overall aim of the study was to disclose potential routes of transmission of these microorganisms. As a first step, the genetic diversity among isolates from AIDS patients and non-human immunodeficiency virus (HIV)-infected patients was described. In addition, a number of isolates from nonhuman sources cultured during the same period were analyzed and compared to the human isolates. A total of 203 isolates from AIDS patients (n = 90), non-HIV-infected patients (n = 91), and nonhuman sources (n = 22) were analyzed. The presence of IS1245 was restricted to Mycobacterium avium subsp. avium isolates. The majority of human isolates had large numbers of IS1245 copies, while nonhuman isolates could be divided into a high-copy-number group and a low-copy-number group. Groups of identical strains were found to be geographically widespread, comprising strains from AIDS patients as well as strains from non-HIV-infected patients. Samples of peat (to be used as potting soil) and veterinary samples were found to contain viable M. avium isolates belonging to genotypes also found in humans.

AIDS-Related Opportunistic Infections↗

Usefulness of spoligotyping To discriminate IS6110 low-copy-number Mycobacterium tuberculosis complex strains cultured in Denmark.

Mycobacterium tuberculosis complex strains cultured in Denmark have been analyzed by IS6110 restriction fragment length polymorphism (RFLP) on a routine basis from 1992 and onwards. Due to the influx of immigrants with tuberculosis, the number of strains harboring only one to five copies of IS6110 has increased steadily. Since the discriminatory power of IS6110 fingerprinting for such strains is poor, we have performed additional genotyping of all low-copy-number strains by the recently described PCR-based method known as spoligotyping. A total of 311 clinical strains were typed: 14 Mycobacterium bovis BCG, 48 M. bovis, and 249 M. tuberculosis strains. Spoligotyping correctly differentiated M. bovis and M. bovis BCG from M. tuberculosis strains, but it did not differentiate M. bovis from M. bovis BCG. All M. bovis BCG strains exhibited identical spoligotype patterns. The discriminatory power of spoligotyping of low-copy-number M. tuberculosis strains was higher than that of IS6110 fingerprinting. Based on RFLP typing solely, 83% of the low-copy-number M. tuberculosis strains were found to form part of a cluster, and 75% were found to form a cluster on the basis of spoligotyping. When the two techniques were combined, the amount of clustering decreased to 55%. The combination of these two techniques might be valuable in studying the epidemiology of M. tuberculosis strains harboring few copies of the IS6110 element.

DNA Fingerprinting↗

ANG II- and TxA(2)-induced mesenteric vasoconstriction in rats is mediated by separate cell signaling pathways.

Studies in vitro have demonstrated that vasoconstrictor agents increase intracellular Ca(2+) and activate protein kinase C (PKC) to elevate vascular tone. The aim of the present study was to determine the importance of these signaling pathways for angiotensin II (ANG II) and thromboxane A(2) (TxA(2)) in regulating mesenteric blood flow (MBF) in vivo. In anesthetized rats increasing doses of ANG II or the TxA(2) agonist U-46619 were administered into the superior mesenteric artery to reduce MBF. Intra-arterial infusion of inhibitors served to examine the contribution of different pathways: 8-(diethylamino)octyl 3,4,5-trimethoxybenoate hydrochloride (TMB-8) to inhibit intracellular Ca(2+) release, nifedipine to block transmembrane Ca(2+) influx through the L-type Ca(2+) channel, and staurosporine to inhibit PKC. Each of the inhibitors attenuated ANG II-induced reductions in MBF, and all dose-response curves were shifted to the right to an approximately threefold higher ANG II dose. Combinations of the inhibitors revealed that their effects were additive; together they abolished the vasoconstrictor action of ANG II completely. In contrast, the dose-response curve for U-46619 was not affected by any of the inhibitors infused either separately or together. The results demonstrate that a rise in intracellular Ca(2+) and activation of PKC are major mediators of the vasoconstrictor effect of ANG II in mesenteric circulation, but they play a subordinate role, if any, for the effects of TxA(2). Because TxA(2) plays a major role only under pathological conditions, the uncontrolled vasoconstriction appears to be associated with the recruitment of novel signal transduction pathways.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗

Quantification of conversion and degradation of circulating angiotensin in rats.

The aim of the present study was to quantify with a uniform technique the rates of conversion of ANG I to ANG II in the lung and kidney and the degradation of both peptides to biologically inactive products in the pulmonary, renal, and systemic circulation. We infused the peptides intravenously, into the left ventricle, and into the left renal artery of rats and compared their effects on renal blood flow. The measured change in renal blood flow was used as a bioassay parameter to estimate the concentration of circulating ANG II. Mathematical analysis of our data allowed us to calculate conversion and degradation rates. Furthermore, the role of aminopeptidases A (EC 3.4.11.7) and N (EC 3.4.11.2) in the degradation of the peptides in the kidney was investigated by intrarenal infusion of the inhibitor amastatin. Our results show that the conversion rate of ANG I is 75% in the pulmonary and 21% in the renal circulation. Both peptides are degraded by 5% in the pulmonary, by 67% in the systemic, and by 93% in the renal circulation. Amastatin prevented 60% of the renal degradation of the peptides to inactive products, and this effect could be attributed to inhibition of aminopeptidase N. The results indicate that the converting capacity of the kidney is of minor importance for endocrine generation of ANG II but could be useful for the paracrine production.

Aminopeptidases↗

Phase II study of oral platinum drug JM216 as first-line treatment in patients with small-cell lung cancer.

PURPOSE: This multicenter phase II trial was performed to determine tumor efficacy and tolerance of the oral platinum drug JM216 in patients with small-cell lung cancer (SCLC). PATIENTS AND METHODS: Patients with SCLC limited disease unfit for intensive chemotherapy or those with extensive disease received JM216 120 mg/m(2)/d for 5 consecutive days every 3 weeks. Individual dose escalation to 140 mg/m(2)/d was allowed if toxicity was </= grade 2 according to the National Cancer Institute Common Toxicity Criteria. Tumor response was evaluated according to World Health Organization criteria. RESULTS: Twenty-seven patients were assessable for toxicity and 26 for tumor response. Eighty-eight cycles were administered. Common Toxicity Criteria grade 3 and 4 hematologic toxicities were neutropenia in 15.9% and 3.7%, lymphocytopenia in 47.6% and 17.1%, and thrombocytopenia in 19.5% and 10.3% of cycles, respectively. One patient suffered from neutropenic fever. Nausea, vomiting, and diarrhea were the most common nonhematologic toxicities. Except for grade 4 diarrhea in one patient, no grade 4 nonhematologic toxicity was observed. No severe neurotoxicity or nephrotoxicity was observed. Tumor response rate was 10 of 26 (38%; 95% confidence interval, 19% to 58%), excluding five unconfirmed partial responses. No complete responses were observed. Median overall time to progression was 110 days (range, 5 to 624 days). Median overall survival time was 210 days (range, 5 to 624 days). CONCLUSION: Oral JM216 is active in previously untreated patients with SCLC and shows mild toxicities.

Aged↗

[Goal-oriented outcome measurement in inpatient or day care orthopedic-rheumatologic rehabilitation of patients with back pain].

The comparison of patient characteristics and effectiveness of inpatient rehabilitation (IPR) and outpatient rehabilitation (OPR) is of growing importance in terms of flexible and cost-effective structures in rehabilitation. The effectiveness of the treatment is measured applying a goaloriented approach based on the individual rehabilitation goals and the attainment of these goals at the end of the programme. The frequencies of rehabilitation goals chosen by patients in IPR and OPR are similar. Decrease of pain, improvement of muscular strength and improvement of the range of motion are the main goals of patients in IPR and OPR (92-56%). No relevant differences can be seen considering the effectiveness of IPR and OPR, except for the markedly higher improvement of vitality in IPR. Patients in need of rehabilitation whose primary rehabilitation goal is improvement of vitality should therefore preferentially be referred to an inpatient rehabilitation programme.

Adult↗

[In vitro evaluation of potentially effective gemcitabine combination therapy for exocrine pancreatic carcinoma].

The aim of the present study was to define potentially synergistic gemcitabine drug combinations for the treatment of pancreatic adenocarcinoma by using a tumour-specific in vitro screening system. The anticancer drug screening system used for these experiments consisted of four different established human pancreatic adenocarcinoma cell lines (BxPc-3, Panc-1, ASPC-1, Ca-pan-1) and the Microculture Tetrazolium (MTT) Assay for quantification of cytotoxic drug effects. To define single agent activities, dose-response curves, IC 50 values, and in order to validate the test system, in a first step gemcitabine and several conventional anticancer drugs including 5-FU, cisplatin, epirubicin, and mitomycin C were tested at 10 different concentrations ranging from 0.001 to 100 micrograms/ml. The effectiveness of various gemcitabine combinations was subsequently determined by using clinically relevant in vitro drug concentrations, and was rated as synergistic, additive or subadditive according to the criteria of Aapro. Overall, a heterogeneous chemosensitivity pattern was noted within the four tested cell lines. In agreement with the known chemotherapeutic refractoriness of pancreatic cancer, major cytotoxic effects were only seen with use of rather high drug concentrations. Investigation of various drug exposure times revealed a superior antiproliferative activity of gemcitabine and the other compounds in case of prolonged incubation. During subsequent drug combination experiments, gemcitabine + cisplatin and gemcitabine + epirubicin resulted in synergistic activity in 2/4 cell lines each. As opposed to the poor activity of single agents, a > 50% growth inhibition (in vitro response) was noted in 3 and 2 cell lines, respectively. Experimental data obtained with this pancreatic cancer specific in vitro screening system suggest that dose escalation or prolonged administration of gemcitabine, as well as the combination of this drug with cisplatin or epirubicin might result in improved therapeutic results. Encouraging preliminary results obtained in phase II studies seem to support the potential clinical relevance of the described disease-oriented screening system.

Adenocarcinoma↗

Prostate biopsy schemes: 3-D visualization-based evaluation.

We have developed a prostate needle biopsy visualization system for the evaluation and optimization of biopsy schemes. Three-dimensional (3-D) prostate surface models have been reconstructed from the digitized whole-mount radical prostetactomy specimens with localized cancers. We have conducted evaluation of five major biopsy schemes with a total of 201 3-D prostate models. These are sextant, 10-pattern, 12-pattern, 14-pattern, and the 5-region schemes. The 10- and 12-pattern biopsy schemes had a 99.0% detection rate, while the rate of traditional sextant biopsy scheme was only 72.6%. The 5-region biopsy scheme had a 90.5% detection rate and the 14-pattern, which includes all the biopsies used in the above schemes, added only one additional positive case (99.5%). Our results suggest that biopsy schemes that use laterally placed biopsies based on the five region anatomical model are superior to the routinely used sextant biopsy scheme. Significant correlation is found between the tumor volume and the positive needle core volume for each of these five schemes. The 10-pattern scheme is the best in cancer detection among these five biopsy schemes.

Biopsy, Needle↗

Interpreting DNA fingerprint clusters of Mycobacterium tuberculosis. European Concerted Action on Molecular Epidemiology and Control of Tuberculosis.

Many studies of tuberculosis have defined clusters of patients on the basis of shared DNA fingerprint patterns of their Mycobacterium tuberculosis isolates. Clustering has been equated with recent transmission, and factors associated with clustering have been sought as a guide to population subgroups with high rates of ongoing transmission of M. tuberculosis. Considerable caution should be exercised in conducting and interpreting these studies. Groups of strains may be identical for reasons other than recent transmission, depending, for example, on the stability of the marker and the number of strains in the population over time. Cases actually due to recent transmission may not be seen as clustered if they are new immigrants to the population or if not all cases in the population are included in the study. The amount of clustering seen will depend on the duration of the study. Studies should give precise information on the study setting, the proportion of cases included, the recruitment period and the definition of clustering used. The data on clustering should be disaggregated at least by age, sex and immigration status. To be maximally informative, studies should involve a high proportion of all cases in a population, be conducted in conjunction with conventional epidemiological investigations of contacts (if possible), and should provide information on tuberculosis incidence in the population and on patients' age, sex, human immunodeficiency virus status, drug resistance and social and ethnic group.

Cluster Analysis↗

Simultaneous myocardial revascularization and aortic valve replacement: stentless versus stented bioprostheses.

Implantation of stentless aortic valve prostheses is more time-consuming than implantation of conventional stented bioprostheses. Simultaneous myocardial revascularization can result in a considerably prolonged operation time. We reviewed our patients with regard to surgical aspects in the specific patient cohorts. From April 1996 to April 1999, 303 patients were operated for aortic valve disease with or without concomitant coronary artery revascularization. Mean age was 75 years, ranging between 36 and 90 years. Using the Medtronic Freestyle valve, the following techniques of implantation were used: subcoronary technique, 163 patients, 61.5%; root inclusion technique, 7 patients, 3.5%; total root replacement, 30 patients, 15%. Total hospital mortality rate was 5.6%, reflecting age and concomitant disease of these patients. For isolated aortic valve replacement, the mortality rate was 4.7% and 6.7% for combined procedures. Coronary artery patients who are not suitable for stentless valve implantation owing to extensive aortic root calcification have a higher perioperative mortality rate. Compared with the isolated valve replacement and despite more extensive surgery and prolonged operative time, simultaneous myocardial revascularization in patients with stentless prostheses implantation can be performed without an increased risk.

Adult↗

Electrophoresis in space.

Programs for free flow electrophoresis in microgravity over the past 25 years are reviewed. Several studies accomplished during 20 spaceflight missions have demonstrated that sample throughput is significantly higher in microgravity than on the ground. Some studies have shown that resolution is also increased. However, many cell separation trials have fallen victim to difficulties associated with experimenting in the microgravity environment such as microbial contamination, air bubbles in electrophoresis chambers, and inadequate facilities for maintaining cells before and after separation. Recent studies suggest that the charge density of cells at their surface may also be modified in microgravity. If this result is confirmed, a further cellular mechanism of "sensing" the low gravity environment will have been found. Several free fluid electrophoresis devices are now available. Most have been tried at least once in microgravity. Newer units not yet tested in spaceflight have been designed to accommodate problems associated with space processing. The USCEPS device and the Japanese FFEU device are specifically designed for sterile operations, whereas the Octopus device is designed to reduce electroosmotic and electrohydrodynamic effects, which become dominant and detrimental in microgravity. Some of these devices will also separate proteins by zone electrophoresis, isotachophoresis, or isoelectric focusing in a single unit. Separation experiments with standard test particles are useful and necessary for testing and optimizing new space hardware. A cohesive free fluid electrophoresis program in the future will obviously require (1) flight opportunities and funding, (2) identification of suitable cellular and macromolecular candidate samples, and (3) provision of a proper interface of electrophoresis processing equipment with biotechnological facilities--equipment like bioreactors and protein crystal growth chambers. The authors feel that such capabilities will lead to the production of commercially useful quantities of target products and to an accumulation of new knowledge relating to the complexities of electrostatic phenomena at the cell surface.

Animals↗

Huntington's disease: the relationship between clinical signs, CAG repeats and the atrophy of the caudate nucleus in CT scans.

We compared clinical data from 45 patients with Huntington's Disease (HD) with CAG triplet repeats and the planimetric measurement of the caudate nucleus head area (CNHA) in CT scans. The mean age of patients was 50.4 yrs (SD +/- 10.2), the mean duration of HD 7.4 yrs (4.6), the mean age at the onset of HD 43.1 yrs (11.1). HD started with motor symptoms in 28 patients, with psychiatric symptoms in 14 patients, the history was unknown in 3 patients. The paternal transmission was observed in 29 patients, the maternal one in 12 patients, unknown in 4 patients. The mean number of CAG repeats was 46.6 (6.1). The mean CNHA was 0.4 cm2 (0.1). We found statistically significant reversed correlation between CAG repeats and the age at the onset of HD (p < 0.0001, r -0.6). The earlier onset of HD in patients with the paternal transmission compared to the maternal one was found statistically significant (p < 0.05). This phenomenon was not related to the larger number of CAG triplets in patients with the paternal transmission. No differences either of the age at the onset of HD or numbers of CAG repeats were found between subgroups of HD patients starting with motor or psychiatric symptoms. We also observed the significant reversed correlation between the duration of HD and CNHA measurement (p < 0.001, r -0.5). Even in the earliest stage of HD patients showed the marked atrophy of CNHA.

Atrophy↗

The low density lipoprotein receptor gene family. Differential expression of two alpha2-macroglobulin receptors in the brain.

LR7/8B is a member of the low density lipoprotein receptor gene family that is specifically synthesized in the brain. Here we have functionally expressed in 293 cells the splice variant harboring eight ligand binding repeats (LR8B). As assessed by confocal microscopy, the expressed receptor is localized to the plasma membrane. Importantly, in cell binding experiments, we demonstrate that this protein is a receptor for activated alpha2-macroglobulin. Because to date low density lipoprotein receptor-related protein (LRP) has been shown to be the only alpha2-macroglobulin receptor in brain, we became interested in the expression pattern of both proteins at the cellular level in the brain. LR7/8B is expressed in large neurons and Purkinje cells of the cerebellum and in cells constituting brain barrier systems such as the epithelial cells of the choroid plexus, the arachnoidea, and the endothelium of penetrating blood vessels. Anti-LR7/8B antibody stains the plasma membrane, dendrites, and vesicular structures close to the cell membrane of neurons, especially of Purkinje cells. In contrast, LRP is present in patchy regions around large neurons and most prominently in the glomeruli of the stratum granulare of the cerebellum. This suggests that, contrary to LR7/8B, LRP is expressed in synaptic regions of the neurons; furthermore, there is a striking difference in the expression patterns of LR7/8B and LRP in the choroid plexus. Whereas LRP shows baso-lateral and apical localization in the epithelial cells, LR7/8B is restricted to the apical cell aspect facing the cerebrospinal fluid. Finally, these studies were extended to cultured primary rat neurons, where double immunofluorescence labeling with anti-LR7/8B and anti-microtubuli-associated protein 2 (MAP2) confirmed the somatodendritic expression of the receptor. Based upon these data, we propose that LR7/8B is involved in the clearance of alpha2-macroglobulin.proteinase complexes and/or of other substrates bound to alpha2-macroglobulin from the cerebrospinal fluid and from the surface of neurons.

Alternative Splicing↗

Insulin-mimetic signalling of synthetic phosphoinositolglycans in isolated rat adipocytes.

A set of synthetic phosphoinositolglycan (PIG) compounds has been demonstrated to exert insulin-mimetic activity on glucose and lipid metabolism in rat adipocytes differing considerably in potency [compound 41>37>45>>7>1; W. Frick, A. Bauer, J. Bauer, S. Wied and G. Müller, G. (1998) Biochemistry 37, 13421-13436]. In the present study we examine whether these differences are based on the capability of the PIG compounds to stimulate signalling components which are thought to mediate metabolic insulin action. Studies using a tyrosine kinase inhibitor and introduction into adipocytes of anti-phosphotyrosine or inhibitory anti-insulin receptor beta-subunit antibodies demonstrated dependence on tyrosine phosphorylation but independence of insulin receptor kinase activation of the insulin-mimetic signalling and metabolic activity of the PIG compounds. The five compounds elicited in rat adipocytes a significant increase in tyrosine phosphorylation of both insulin receptor substrate 1 (IRS-1) and IRS-3 and, to a minor degree, IRS-2, in IRS-1/3-associated phosphatidylinositol 3-kinase (PI 3-K) protein as well as activity, and in protein kinase B (PKB) activity as well as phosphorylation. This was most pronounced for compound 41, approaching 65-95% of the maximal insulin response (MIR) at 20 microM, and declined in the order of compounds 37, 45, 7 and 1. The same ranking was true for the maximal inhibition of glycogen synthase kinase 3 activity (GSK-3) (41, 75% of MIR; compound 37, 65%; compound 7, 25%; compound 1, 10%) and GSK-3 autophosphorylation. The half-maximal concentrations effective for signalling (compound 41, 2-5 microM; compound 37, 10-20 microM) corresponded well to those stimulating glucose and lipid metabolism. Interestingly, compounds 37 and 41 stimulated mitogen-activated protein kinase (MAPK) and protein synthesis in rat adipocytes to only about 20-30% (at 50 microM) of MIR. We conclude that in rat adipocytes: (i) the potency of PIG compounds to regulate glucose/lipid metabolism depends on the activation of PI 3-K and PKB and inhibition of GSK-3; (ii) initiation of tyrosine phosphorylation of IRS-1/3 is sufficient and activation of the PI 3-K cascade is required for insulin-mimetic metabolic signalling; and (iii) PIG compounds are quite selective for the PI 3-K compared to the MAPK cascade, (iv) PIG compounds seem to use the same signalling components downstream of PI 3-K (including Rab4) for stimulation of glucose transport as does insulin. Thus the early signalling step(s) used by PIG, but not by insulin, may represent a target for the treatment of insulin-resistant states.

Adipocytes↗

Cytokine-induced transcription of protein-tyrosine-phosphatases in human astrocytoma cells.

Interleukin-1 (IL-1) and Tumor Necrosis Factor-a (TNFalpha) are potent mediators of inflammatory reactions in the brain. Although much is known about the effects of IL-1 on expression of secretory proteins, few studies have addressed the question of a selective, IL-1-dependent expression of genes involved in neuromodulatory effects of inflammation. Protein-tyrosine-phosphatases (PTP's) have been shown to regulate signal transduction and adhesion processes in the developing nervous system. They are candidates for inflammation-induced neuromodulation. Therefore, we investigated if IL-1 regulates expression of PTP's. We applied a DNA-fingerprinting method based on the PCR-amplification of conserved domains of gene families and observed IL-1-dependent induction of two PTP's, cytoplasmic PTPvarepsilon and receptor-PTPgamma, RPTPgamma, in human U373-MG astrocytoma cells. Using Northern blot analysis, we confirmed this result and also show that in addition to IL-1, TNFalpha but not IL-6 induces the transcription of cytoplasmic PTPvarepsilon and RPTPgamma in human astrocytoma cells. Given the important role for PTP's in neuromodulatory aspects such as axonal guidance and neurite outgrowth, cytokine-induced induction of PTP's may play an important pathenogenic role in the development of chronic inflammatory diseases in the brain.

Astrocytoma↗

Proteins of newly isolated mutants and the amino-terminal proline are essential for ubiquitin-proteasome-catalyzed catabolite degradation of fructose-1,6-bisphosphatase of Saccharomyces cerevisiae.

Addition of glucose to cells of the yeast Saccharomyces cerevisiae growing on a non-fermentable carbon source leads to selective and rapid degradation of fructose-1,6-bisphosphatase. This so called catabolite inactivation of the enzyme is brought about by the ubiquitin-proteasome system. To identify additional components of the catabolite inactivation machinery, we isolated three mutant strains, gid1, gid2, and gid3, defective in glucose-induced degradation of fructose-1,6-bisphospha-tase. All mutant strains show in addition a defect in catabolite inactivation of three other gluconeogenic enzymes: cytosolic malate dehydrogenase, isocitrate lyase, and phosphoenolpyruvate carboxykinase. These findings indicate a common mechanism for the inactivation of all four enzymes. The mutants were also impaired in degradation of short-lived N-end rule substrates, which are degraded via the ubiquitin-proteasome system. Site-directed mutagenesis of the amino-terminal proline residue yielded fructose-1,6-bisphosphatase forms that were no longer degraded via the ubiquitin-proteasome pathway. All amino termini other than proline made fructose-1,6-bisphosphatase inaccessible to degradation. However, the exchange of the amino-terminal proline had no effect on the phosphorylation of the mutated enzyme. Our findings suggest an essential function of the amino-terminal proline residue for the degradation process of fructose-1,6-bisphosphatase. Phosphorylation of the enzyme was not necessary for degradation to occur.

Amino Acid Sequence↗