Biomedical subjects

M Moser

Publications and source records attributed to M Moser.

At least 91 records · Page 5Linked to original sources

PubMed1999

Crystal structure of GABA-aminotransferase, a target for antiepileptic drug therapy.

gamma-Aminobutyrate aminotransferase (GABA-AT), a pyridoxal phosphate-dependent enzyme, is responsible for the degradation of the inhibitory neurotransmitter GABA and is a target for antiepileptic drugs because its selective inhibition raises GABA concentrations in brain. The X-ray structure of pig GABA-AT has been determined to 3.0 A resolution by molecular replacement with the distantly related enzyme ornithine aminotransferase. Both omega-aminotransferases have the same fold, but exhibit side chain replacements in the closely packed binding site that explain their respective specificities. The aldimines of GABA and the antiepileptic drug vinyl-GABA have been modeled into the active site.

4-Aminobutyrate Transaminase↗

PubMed1999

Hypertension treatment and the prevention of coronary heart disease in the elderly.

Both isolated systolic hypertension (>140 mm Hg/<90 mm Hg) and systolic/diastolic hypertension (>140 mm Hg/>90 mm Hg) are major risk factors for cardiovascular disease in the elderly. Specific antihypertensive drug therapy is available if lifestyle interventions fail to reduce blood pressure to a normal level. Diuretics and beta blockers both reduce the occurrence of adverse events related to cerebrovascular disease; however, diuretics are more effective in reducing events related to coronary heart disease. Treated patients are less likely to develop severe hypertension or congestive heart failure. In most instances, low-dose diuretic therapy should be used as initial antihypertensive therapy in the elderly. A long-acting dihydropyridine calcium channel blocker may be used as alternative therapy in elderly patients with isolated systolic hypertension. Trials are being conducted to evaluate the long-term effects of angiotensin converting enzyme inhibitors and angiotensin-II receptor blockers in elderly patients with uncomplicated hypertension.

Aged↗

PubMed1999

Crystal structure of phosphoserine aminotransferase from Escherichia coli at 2.3 A resolution: comparison of the unligated enzyme and a complex with alpha-methyl-l-glutamate.

Phosphoserine aminotransferase (PSAT; EC 2.6.1.52), a member of subgroup IV of the aminotransferases, catalyses the conversion of 3-phosphohydroxypyruvate to l-phosphoserine. The crystal structure of PSAT from Escherichia coli has been solved in space group P212121 using MIRAS phases in combination with density modification and was refined to an R-factor of 17.5% (Rfree=20.1 %) at 2.3 A resolution. In addition, the structure of PSAT in complex with alpha-methyl-l-glutamate (AMG) has been refined to an R-factor of 18.5% (Rfree=25.1%) at 2.8 A resolution. Each subunit (361 residues) of the PSAT homodimer is composed of a large pyridoxal-5'-phosphate binding domain (residues 16-268), consisting of a seven-stranded mainly parallel beta-sheet, two additional beta-strands and seven alpha-helices, and a small C-terminal domain, which incorporates a five-stranded beta-sheet and two alpha-helices. A three-dimensional structural comparison to four other vitamin B6-dependent enzymes reveals that three alpha-helices of the large domain, as well as an N-terminal domain (subgroup II) or subdomain (subgroup I) are absent in PSAT. Its only 15 N-terminal residues form a single beta-strand, which participates in the beta-sheet of the C-terminal domain. The cofactor is bound through an aldimine linkage to Lys198 in the active site. In the PSAT-AMG complex Ser9 and Arg335 bind the AMG alpha-carboxylate group while His41, Arg42 and His328 are involved in binding the AMG side-chain. Arg77 binds the AMG side-chain indirectly through a solvent molecule and is expected to position itself during catalysis between the PLP phosphate group and the substrate side-chain. Comparison of the active sites of PSAT and aspartate aminotransferase suggests a similar catalytic mechanism, except for the transaldimination step, since in PSAT the Schiff base is protonated. Correlation of the PSAT crystal structure to a published profile sequence analysis of all subgroup IV members allows active site modelling of nifs and the proposal of a likely molecular reaction mechanism.

Alanine Transaminase↗

PubMed1999

Influence of age on the parasympatholytic property of tricyclic antidepressants.

Clinical evidence indicates that parasympatholytic effects of tricyclic antidepressants increase with age. The aim of the present study was to determine the possible physiological reason for this phenomenon. Subjects included 23 patients (14 female) with major depression, melancholic type, and 23 age- and sex-matched healthy control subjects. Cardiac vagal tone was measured at rest using both spectral analysis and a time domain beat-to-beat method. Results of the spectral and time domain methods for the estimation of vagal tone used in this study were highly correlated in control subjects as well as in medicated depressed subjects. Both patients and control subjects showed an age-related decline in cardiac vagal tone. Tricyclic antidepressants decreased vagal tone significantly by 25-49% depending on age (20-60 years), although the age difference was not significant. The greater effect of tricyclic antidepressants on parasympathetic activity typically seen in older age groups may reflect the fact that predrug levels of vagal tone are already low in older patients. Measurement of vagal tone prior to drug administration may therefore be of prognostic value for anticholinergic side effects.

Adult↗

PubMed1999

CD8alpha+ and CD8alpha- subclasses of dendritic cells direct the development of distinct T helper cells in vivo.

Cells of the dendritic family display some unique properties that confer to them the capacity to sensitize naive T cells in vitro and in vivo. In the mouse, two subclasses of dendritic cells (DCs) have been described that differ by their CD8alpha expression and their localization in lymphoid organs. The physiologic function of both cell populations remains obscure. Studies conducted in vitro have suggested that CD8alpha+ DCs could play a role in the regulation of immune responses, whereas conventional CD8alpha- DCs would be more stimulatory. We report here that both subclasses of DCs efficiently prime antigen-specific T cells in vivo, and direct the development of distinct T helper (Th) populations. Antigen-pulsed CD8alpha+ and CD8alpha- DCs are separated after overnight culture in recombinant granulocyte/macrophage colony-stimulating factor and injected into the footpads of syngeneic mice. Administration of CD8alpha- DCs induces a Th2-type response, whereas injection of CD8alpha+ DCs leads to Th1 differentiation. We further show that interleukin 12 plays a critical role in Th1 development by CD8alpha+ DCs. These findings suggest that the nature of the DC that presents the antigen to naive T cells may dictate the class selection of the adaptative immune response.

Animals↗

PubMed1999

Retrovirally transduced bone marrow-derived dendritic cells require CD4+ T cell help to elicit protective and therapeutic antitumor immunity.

It has been extensively documented that murine dendritic cells loaded with tumor-associated Ag (TAA)-derived peptides or protein can prime Ag-specific CD8+ cytotoxic T cells in vivo and can elicit Ag-specific immunity. Optimal presentation of TAA might be achieved by retroviral transduction of DCs allowing long term and stable expression of the TAA-peptides as well as the presentation of multiple epitopes in the context of MHC class I and/or class II molecules. Here we show that retroviral transduction of bone marrow-derived dendritic cells (DCs) with chicken OVA cDNA or the reporter gene green fluorescent protein retained their potent stimulatory capacity and that the transduced DCs could process and present the endogenously expressed OVA protein. The DCs transduced with cDNA encoding native OVA protein presented OVA-derived peptides in the context of MHC class I as well as MHC class II and induced a strong Ag-specific CTL response. DCs expressing a cytosolic form of OVA presented OVA peptides only in the context of MHC class I and failed to induce an OVA-specific CTL response in vivo when they had been cultured in the absence of exogenous protein. Immunization with retrovirally transduced DCs resulted in an Ag-specific immunity and rejection of a tumor cell challenge and a significant survival advantage in tumor-bearing mice. These results obtained in this rapidly lethal tumor model suggest that DCs transduced with TAA may be useful for tumor immunotherapy and underscore the importance of the simultaneous delivery of T cell help in the development of Ag-specific cytotoxic T-cells.

Animals↗

PubMed1999

In situ expression patterns of melanoma-inhibiting activity (MIA) in melanomas and breast cancers.

Elevated levels of melanoma-inhibiting activity (MIA) were measured previously in the serum of patients with metastasized melanomas and in a subgroup of patients with advanced-stage breast cancers. This study aimed therefore to visualize in situ expression patterns of MIA protein and mRNA in melanomas and breast cancers by means of immunohistochemistry, reverse transcription-polymerase chain reaction (RT-PCR), and in situ hybridization. Analysis of a panel of seven common melanocytic naevi, ten cutaneous melanomas, and 12 melanoma metastases detected high levels of both mRNA and protein in all melanomas and metastases, but only very low mRNA levels in three of seven naevi. Compared with the expression of pMel (HMB-45), tyrosine, and S-100 in these tumours, these results show that MIA provides a novel and sensitive marker for neoplastic melanocytes. Expression was not detected in other skin tumours including basal cell cancers and squamous cell cancers, nor in normal melanocytes and keratinocytes. MIA expression in adenocarcinomas was further studied in a panel of 20 specimens obtained from 16 advanced-stage breast cancers and four metastases. Significant levels of mRNA were detected in 17 of the 20 specimens and low levels in the other three tumours. Immunostaining visualized specific protein expression in the tumour cells of all 20 cancer specimens. These investigations define for the first time in situ expression patterns of MIA in melanomas and breast cancers and suggest a much broader expression in malignant epithelial neoplasms than previously determined by serum studies.

Adenocarcinoma↗

PubMed1999

Role of CD8alpha+ and CD8alpha- dendritic cells in the induction of primary immune responses in vivo.

Data from adoptive transfer of mature dendritic cells (DC) indicate that they are responsible for the induction of primary immunity. Two subclasses of DC have been recently identified in spleen that differ in their phenotype and in certain regulatory features. In vitro, both subsets have the capacity to activate naive T cells, although CD8a+ DC have been shown to induce T cell apoptosis and to stimulate lower levels of cytokines compared with CD8alpha- DC. The objective of this study was to analyze the function of these distinct DC types in vivo. Our results show that both subsets, pulsed extracorporeally with antigen and injected in the footpads of syngeneic mice, sensitize an antigen-specific T cell primary response. However, CD8alpha+ cells trigger the development of Thl-type cells, whereas CD8alpha- DC induce a Th2-type response. These observations suggest that the Th1/Th2 balance in vivo is regulated by the antigen-presenting-cells of the primary immune responses.

Adjuvants, Immunologic↗

PubMed1999

Validation of a western immunoblotting procedure for bovine PrP(Sc) detection and its use as a rapid surveillance method for the diagnosis of bovine spongiform encephalopathy (BSE).

In this report we document the results of several independent studies testing the sensitivity, specificity and reliability of the Prionics Western blotting (PWB) procedure to detect bovine and ovine disease-specific, protease-resistant prion protein (PrP(Sc)). Validation of the technique was obtained by blind analysis of samples from cattle affected with bovine spongiform encephalopathy (BSE), clinically normal animals or cattle with neurological diseases unrelated to BSE. Overall, very high sensitivity, specificity and reliability was observed. It became clear that sampling of the correct brain region and the method used for protein extraction are important factors for correct diagnosis. Furthermore, we tested the usefulness of the PWB technique as an instrument for surveillance purposes. We analyzed animals from a culling scheme as well as older animals from abattoirs to determine the number of subclinical BSE cases detectable by histopathological examination, immunohistochemistry for PrP(Sc) and PWB. In both studies, BSE-affected animals with no overt clinical symptoms were detected. These results demonstrate the usefulness of the PWB procedure in surveillance systems serving as a rapid diagnostic tool to identify animals subclinically infected with BSE.

Animals↗

PubMed1999

Elective transfer of embryos selected on the basis of first polar body morphology is associated with increased rates of implantation and pregnancy.

OBJECTIVE: To determine the relationship between first polar body morphology and implantation rate and pregnancy rate (PR), to facilitate decision making concerning elective ET. DESIGN: Prospective, randomized study. SETTING: Fertility center. PATIENT(S): One hundred fifty-eight consecutive patients (173 intracytoplasmic sperm injection cycles) resulting in embryo transfers. INTERVENTION(S): In our study group, priority in ET was given to embryos derived from well-shaped first polar bodies, whereas selection of embryos for transfer in the control group was based exclusively on the degree of embryo fragmentation. MAIN OUTCOME MEASURE(S): Total numbers of implantations and pregnancies, PR and implantation rate, and rates of multiple pregnancy and miscarriage. RESULT(S): In the study cohort, 212 embryos were transferred. In the control group, 313 embryos were transferred. The implantation rate and PR were significantly lower in the control group than in the study cohort. In addition, the rate of multiple pregnancy was significantly higher in the study group. CONCLUSION(S): Elective transfer of embryos selected on the basis of first polar body morphology results in higher implantation and pregnancy rates. Multiple pregnancy can be avoided by transferring a reduced number of embryos selected on the basis of first polar body morphology.

Adult↗

PubMed1999

Reproducibility of transvaginal three-dimensional endometrial volume measurements during ovarian stimulation.

Before estimating the clinical role of a method, the reproducibility has to be evaluated precisely. This study aimed to document the reproducibility of the endometrial volume measurement by three-dimensional (3D)-ultrasound. The volume measurements were done on 57 consecutive in-vitro fertilization (IVF) patients with either the full planar (contour) or the three distance method. A paired t-test provided no statistically significant difference between the two methods. Linear regression analysis, using the full planar method as independent and the other as dependent variables, yielded the following results: intercept = 0.348, not statistically different from 0; slope = 0.962, statistically different from 1 (P < 0.01). Interobserver reliability for the three distance method was 0.6667 and for the full planar method was 0.9565. Intra-observer reliability for the three distance method was 0.8426 and for the full planar method 0.9394. The correspondence between and within observers seemed to be good. Both methods are reliable, but the full planar method seems to provide slightly better reproducibility in regard to endometrium volume measurement.

Adult↗

PubMed1999

Role and regulation of IL-12 in the in vivo response to staphylococcal enterotoxin B.

Injection of a staphylococcal superantigen (SAg) such as staphylococcal enterotoxin B (SEB) in adult mice results in cytokine production and cell proliferation which can lead to septic shock. The aim of the present work was to identify the cytokines and co-stimulatory molecules regulating the in vivo systemic release of IFN-gamma, a cytokine known to play an important role in the pathophysiology associated with bacterial infections. We demonstrate in this study that (i) in contrast to lipopolysaccharide (LPS), SEB administration induces high levels of the p70, bioactive form, of IL-12; (ii) IL-12 production in response to SEB requires both CD40-dependent signals and IFN-gamma secretion; (iii) the early systemic release of IFN-gamma (3 h post-treatment) in response to SEB is IL-12 independent, while the sustained, late response (6-9 h post-treatment) requires endogenous IL-12 production; (iv) IL-12 produced during the primary SEB response (day 0) is responsible for priming cells in vivo to high IFN-gamma production upon secondary challenge (day 2); (v) the priming effect of IL-12 is TCR unrelated, as SEB-primed animals secrete high levels of IFN-gamma in response to both staphylococcal enterotoxin A and LPS administered 48 h later. The ability of bacterial SAg to induce septic shock and to modulate the immune response to unrelated antigens may therefore be related to their unique capacity to induce systemic IL-12 production in vivo. These observations also help to explain why SEB-primed animals, known to express an anergic phenotype 48 h post-treatment (as judged by defective IL-2 production and proliferation), nevertheless display an increased capacity to secrete the inflammatory cytokine IFN-gamma.

Animals↗

PubMed1999

Susceptibility of bovine antigen-presenting cells to infection by bovine herpesvirus 1 and in vitro presentation to T cells: two independent events.

The aim of the present study was to develop an in vitro system for presentation of bovine herpesvirus 1 (BHV-1) antigens to bovine T lymphocytes and to characterize the antigen-presenting cells (APC) which efficiently activate CD4(+) T cells. Two approaches were used to monitor the infection of APC by BHV-1 as follows: (i) detection of viral glycoproteins at the cell surface by immunofluorescence staining and (ii) detection of UL26 transcripts by reverse transcription-PCR. The monocytes were infected, while dendritic cells (DC) did not demonstrate any detectable viral expression. These data suggest that monocytes are one site of replication, while DC are not. The capacities of monocytes and DC to present BHV-1 viral antigens in vitro were compared. T lymphocytes (CD2(+) or CD4(+)) from BHV-1 immune cattle were stimulated in the presence of APC previously incubated with live or inactivated wild-type BHV-1. DC stimulated strong proliferation of Ag-specific T cells, while monocytes were poor stimulators of T-cell proliferation. When viral attachment to the surface of the APC was inhibited by virus pretreatment with soluble heparin, T-cell proliferation was dramatically decreased. Unexpectedly, incubation of DC and monocytes with the deletion mutant BHV-1 gD-/-, which displays impaired fusion capacity, resulted in strong activation of T lymphocytes by both APC types. Collectively, these results indicate that presentation of BHV-1 antigens to immune T cells is effective in the absence of productive infection and suggest that BHV-1 gD-/- mutant virus could be used to induce virus-specific immune responses in cattle.

Animals↗

PubMed1999

Transcriptional regulation of the AP-2alpha promoter by BTEB-1 and AP-2rep, a novel wt-1/egr-related zinc finger repressor.

AP-2 transcription factors have been suggested to exert key regulatory functions in vertebrate embryonic development, in tumorigenicity of various cancer cell types, and in controlling cell cycle and apoptotic effector genes. In this study, we investigated transcriptional regulation of the AP-2alpha gene promoter mediated by an autoregulatory element (referred to as A32) with a core consensus AP-2 binding site at position -336 relative to the mRNA initiation site. AP-2 and multiple different nuclear proteins in HeLa and Neuro2A cell extracts form specific bandshifts with the A32 element. By screening a mouse brain cDNA expression library, we isolated two different cDNAs encoding the transcription factor BTEB-1 and a novel zinc finger protein, AP-2rep. AP-2rep reveals a modular structure with homology to transcription factors of the wt-1/egr-1-family. AP-2rep, BTEB-1, and AP-2 interact in a mutually exclusive manner with overlapping binding sites in the A32 element. Transfection studies revealed that BTEB-1 is a strong activator of AP-2alpha promoter activity, whereas cotransfected AP-2alpha resulted in moderate autoactivation of promoter activity. In contrast, AP-2rep confers strong transcriptional repression to the AP-2alpha gene, and we observed an excellent correlation between induction of AP-2rep mRNA expression and downregulation of AP-2alpha mRNA during development of the kidney. In summary, we have identified multiple transcription factors and cloned from an expression library a novel zinc finger silencing factor, AP-2rep, mediating positive and negative regulation of AP-2alpha expression through a set of overlapping cis-regulatory promoter elements.

Amino Acid Sequence↗

PubMed1999

Activation of somatostatin receptor II expression by transcription factors MIBP1 and SEF-2 in the murine brain.

Somatostatin receptor type II expression in the mammalian brain displays a spatially and temporally very restricted pattern. In an investigation of the molecular mechanisms controlling these patterns, we have recently shown that binding of the transcription factor SEF-2 to a novel initiator element in the SSTR-2 promoter is essential for SSTR-2 gene expression. Further characterization of the promoter identified a species-conserved TC-rich enhancer element. By screening a mouse brain cDNA expression library, we cloned a cDNA encoding the transcription factor MIBP1. MIBP1 interacts specifically with both the TC box in the SSTR-2 promoter and with the SEF-2 initiator-binding protein to enhance transcription from the basal SSTR-2 promoter. We then investigated SSTR-2, SEF-2, and MIBP1 mRNA expression patterns in the developing and adult murine brain by Northern blotting and in situ hybridization. While SEF-2 is widely expressed in many neuronal and nonneuronal tissues, MIBP1 expression overlapped precisely with expression of SSTR-2 in the frontal cortex and hippocampus. In summary, our data for the first time define a regulatory role for the transcription factor MIBP1 in mediating spatially and temporally regulated SSTR-2 expression in the brain.

Amino Acid Sequence↗

PubMed1999

Pharmacology and clinical trial results of saruplase (scuPA) in acute myocardial infarction.

Saruplase is the non-glycosylated form of single chain urokinase-type plasminogen activator; it is produced by recombinant technique in Escherichia coli. Saruplase has plasminogen activating properties; it can also be cleaved to the potent plasminogen activator, double chain urokinase, resulting in the generation of plasmin. By means of a positive feedback mechanism, plasmin itself is able to cleave saruplase. At present, a bolus of 20 mg followed by an infusion of 60 mg over 1 h and preceded by a heparin bolus of 5000 U, represents the standard saruplase regimen. The PRIMI trial showed that this standard saruplase regimen achieves higher early patency rates than streptokinase. In the COMPASS trial, saruplase has been shown to be at least as effective as streptokinase, in terms of 30 day mortality. A comparative trial with urokinase (SUTAMI) resulted in similar late coronary patency. Saruplase has been tested against alteplase (100 mg over 180 min) in the SESAM trial. The early coronary patency and safety of both regimens were comparable. In a recent study, three bolus applications of saruplase have been investigated. A double bolus of 40 mg each given 30 min apart, is suggested to be more effective than standard saruplase, but concerns about safety remain. Further studies are required to assess safety of the double bolus regimen, and to compare saruplase with the gold-standard of frontloaded alteplase, or the equivalent double bolus reteplase regimen.

Journal Article↗

PubMed1999

Evaluating marrow margins for resection of osteosarcoma. A modern approach.

Intraoperative evaluation of bone marrow margins by frozen section analysis is a common practice in the surgical treatment of osteogenic sarcoma. The purpose of this study was to assess the clinical use of intraoperative marrow margin evaluation to rule out occult intramedullary tumor extension in osteosarcoma surgery. One hundred twenty-eight consecutive patients with high grade osteosarcoma diagnosed between 1988 and 1996 (Group 1) were reviewed retrospectively and compared with 92 consecutive patients treated from 1979 to 1984 (Group 2). Eighty-five patients in Group 1 met the inclusion criteria of having high grade intramedullary lesions of the long bones observed on preoperative magnetic resonance imaging evaluation of the lesion and intraoperative frozen section analysis of the bone marrow margin. Thirty-three patients in Group 2 met the same inclusion criteria with the exception of having preoperative magnetic resonance imaging. Ninety-two marrow margins in Group 1 and 33 marrow margins in Group 2 were evaluated by frozen section. All 92 marrow margins in patients in Group 1 were negative by frozen section analysis and permanent histologic analysis. Of the 33 marrow margins in patients in Group 2, three (9.1%) were reported positive for tumor. Of these, one was found to be a false positive result on permanent pathologic examination. In addition, one false negative frozen section result was found, which was positive for tumor on permanent pathologic examination. The difference in true positive results of marrow margins between Group 1 and Group 2 was statistically significant. Intraoperative marrow margin evaluation by frozen section is not mandatory with modern imaging techniques. Preoperative evaluation of tumor extent using magnetic resonance imaging and intraoperative evaluation of the specimen by the pathologist (done by bivalving the specimen) are reliable methods to ensure adequate surgical margins in most cases of conventional osteosarcoma of the long bones.

Adolescent↗

PubMed1999

Pharmacokinetics and pharmacodynamics of lanoteplase (n-PA).

In acute myocardial infarction rapid, complete, and sustained reperfusion of the infarct-related coronary artery is the most important therapeutic principle. Lanoteplase or n-PA, a third-generation plasminogen activator consisting of a deletion and point mutant of tissue-type plasminogen activator (t-PA), is a promising agent to approach this therapeutic goal. The molecule exhibits an increased plasma half-life allowing single-bolus administration. In this article, after characterizing the n-PA molecule, the currently available pharmacokinetic and pharmacodynamic data including the results of the InTIME study are reviewed.

Animals↗