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Biomedical subjects

M Muller

Publications and source records attributed to M Muller.

At least 181 records · Page 10Linked to original sources
PubMed1996

The E6 variant proteins E6I-E6IV of human papillomavirus 16: expression in cell free systems and bacteria and study of their interaction with p53.

Several species of alternatively spliced mRNAs are transcribed from the E6 gene region of human papillomavirus (HPV) 16. These have the coding capacity for either the full length E6 of 151 amino acids (aa) or four truncated variants, E6I-E6IV, of 43-64 aa. As the first step to identify the putative E6 variants and their functions, we generated cDNAs corresponding to the various E6 open reading frames (ORF) and examined their expression employing in vitro transcription/translation systems and the bacterial pET system. In wheat germ extract, in vitro translation resulted in the production of all five proteins, E6 and E6I-E6IV. These proteins were also expressed as stable fusion proteins from the pET16b and pET17 x b vectors in Escherichia coli. Mobilites of the E6 variant proteins on SDS-acrylamide gels were consistent with their predicted sizes. The authenticity of the synthesized proteins was confirmed by immunoprecipitation with specific antibodies directed against epitopes in the N-terminal portion of E6 as well as antibodies raised against the individual variant proteins produced in E. coli. In rabbit reticulocyte lysate, however, only the full length E6 and the E6IV variant were synthesized. This could be due to inefficient translation as well as lower stability of the short variants. E6I-III, in reticulocyte lysate (RTL). The ability of the E6 variants to associate with p53 and target its proteolytic degradation in vitro, was examined in coimmunoprecipitation assays, using in vitro synthesized proteins and monoclonal antibodies to p53. Results of these assays indicated that only the full length E6 efficiently binds to and promotes the degradation of p53. The E6 variants E6I-E6IV, although able to associate with p53 at a low efficiency, were unable to target its degradation.

Amino Acid Sequence↗
PubMed1996

Correlation between P450 CYP1A1 inducibility, MspI genotype and lung cancer incidence.

The aim of this study was to verify a possible correlation between CYP1A1 induction, MspI genotype and lung cancer incidence. A case-control study was performed on 48 lung cancer patients and 81 healthy subjects to test the existence of a correlation, within a European population. The hyperinducible group exhibited a significantly higher risk of lung cancer (odds ratio = 3.41; P = 0.036), especially for adenocarcinoma (odds ratio = 5.29; P = 0.033). In contrast with the situation observed in Asian populations, the frequency of the M2 allele did not differ significantly in the total lung cancer population (7.82%) and the group of healthy subjects (10.71%). The median inducibility value was slightly higher among cancer patients with one or two M2 alleles than among patients homozygous for the wild-type allele (P = 0.09). However, the percentage of individuals possessing at least one mutated allele was not significantly higher among hyperinducible patients (37.5%) than among non-hyperinducible patients (16.0%). No significant correlation could be found between M2 allele and lung cancer or between M2 allele and CYP1A1 inducibility; the only positive correlation found was between CYP1A1 hyperinducibility and lung cancer incidence. Our observations do not support the view that the presence of the M2 allele at the MspI site of the CYP1A1 gene constitutes a significant lung cancer risk in Caucasians.

Age Factors↗
PubMed1996

Enhancement of nuclear receptor transcriptional signalling.

Glucocorticoids and thyroid hormones induce complex responses in about every mammalian tissue. These effects are mediated by the transcription factor function of the corresponding nuclear receptors, which in most cases achieve the observed regulatory strength in synergy with other factors. Here we describe the functional interaction of the glucocorticoid receptor (GR) with liver-specific transcription factors, the functional synergy of GR with the thyroid hormone receptor (TR), the synergizing sub-domains of the TR, and finally the direct interaction of the GR with other proteins.

Animals↗
PubMed1996

Colonic pseudo-obstruction in burns patients.

Acute pseudo-obstruction is a rare complication in burns patients. An awareness of the factors implicated in its pathogenesis such as prolonged bed rest, narcotic medications, hypokalaemia, sepsis and surgery (all commonly associated with burns patients) is essential if this condition is to be avoided. Early diagnosis, prokinetic and cathartic agents, and aggressive endoscopic intervention are essential to halt the progression of caecal dilatation. Excisional surgery and stoma formation are necessary for salvage of complicated colonic pseudo-obstruction.

Accidents, Occupational↗
PubMed1996

Antitumor activity of a phosphorothioate antisense oligodeoxynucleotide targeted against C-raf kinase.

Substantial evidence exists supporting a direct role for raf kinases in the development and maintenance of certain human malignancies. Here we test the potential of phosphorothioate antisense oligodeoxynucleotides targeted against human C-raf-1 kinase to specifically inhibit C-raf-1 kinase gene expression and tumor progression in cell culture and in vivo, using human tumor xenograft mouse models. Treatment of human tumor cells with appropriate phosphorothioate antisense oligodeoxynucleotides led to specific inhibition of C-raf kinase gene expression in cell culture and in vivo at well-tolerated doses. Moreover, oligodeoxynucleotide treatment resulted in potent antiproliferative effects in cell culture and potent antitumor effects in vivo against a variety of tumor types that were highly consistent with an antisense mechanism of action for these compounds. These studies strongly suggest that antisense inhibitors targeted against C-raf-1 kinase may be of considerable value as antineoplastic agents that display activity against a wide spectrum of tumor types at well-tolerated doses.

Animals↗
PubMed1996

The tilapia prolactin I gene: evolutionary conservation of the regulatory elements directing pituitary-specific expression.

To study the elements involved in the pituitary specific transcriptional regulation of the tilapia prolactin I gene (tiPRL I), we have cloned and entirely sequenced a 3.4-kb genomic fragment immediately upstream from the first exon. In footprinting experiments, three tilapia sequences are protected from DNase I digestion by rat pituitary extracts (base pair coordinates -643 to -593, -160 to -111, and -73 to -46). Computer analysis of the nucleotide sequence reveals significant homology to mammalian binding sites for Pit-1, a transcription factor that is known to mediate pituitary-specific expression of the PRL genes in mammals. The tiPRL I 5'-flanking sequences can direct transient expression of a linked luciferase reporter gene in transfected rat pituitary cell lines and tilapia pituitary primary cell cultures. Transient expression experiments with 5'-deletion mutants reveal three regulatory regions. Two have a stimulatory effect on transcription and one an inhibitory effect. Electrophoretic mobility-shift assays (EMSA) demonstrate that the rat Pit-1 factor specifically binds to tilapia DNA sequences. Several such tilapia Pit-1 binding sites mediate activation of a linked heterologous promoter in transfected rat and tilapia pituitary cells. As evidenced by EMSA, a Pit-1-like protein is present in tilapia pituitary extracts. All these data point to a high conservation of the molecular mechanisms involved in pituitary-specific expression of the PRL genes in vertebrates.

Animals↗
PubMed1996

The enhancers of the human placental lactogen B, A, and L genes: progressive activation during in vitro trophoblast differentiation and importance of the DF-3 element in determining their respective activities.

The hCS-A and hCS-B genes encoding human chorionic somatomammotropin and the related hCS-L gene are very similar in their coding and flanking sequences. For each of these genes, downstream enhancers, varying in strength, have been identified with the help of cytotrophoblast-derived JEG-3 cells, which do not express the hCS genes. Here we study the activity of the hCS enhancers in human syncytiotrophoblast in primary culture, which naturally expresses the hCS genes. We show that the activity of the hCS-B gene enhancer is mediated by two elements, DF-3 and DF-4, whereas the hCS-L and hCS-A gene enhancers display weaker activity due to mutations in their respective DF-3 sites. Replacement of the hCS-B DF-3 site with the homologous hCS-A sequence causes hCS-B enhancer activity to decrease. Primary cytotrophoblasts differentiate in culture to form the syncytiotrophoblast. We show that during this process the production of hCS progressively increases and that concomitantly all three hCS enhancers are progressively activated. A targeted mutation in the 3' part of the DF-4 element abolishes the binding of a protein present only in syncytiotrophoblast extracts and inactivates the DF-4 element. Thus, a direct correlation exists between the appearance of this syncytiotrophoblast-specific protein and hCS enhancer activity. This primary culture model proves useful in studying the regulation of the hCS genes.

Base Sequence↗
PubMed1996

Multiple immune abnormalities in tumor necrosis factor and lymphotoxin-alpha double-deficient mice.

To investigate the roles of tumor necrosis factor (TNF) and lymphotoxin (LT)-alpha in the development and function of the immune system, the Tnf and Ltalpha genes were simultaneously inactivated in mice by homologous recombination. These mutant mice are highly susceptible to Listeria monocytogenes infection and resistant to endotoxic shock induced by the combined administration of D-galactosamine (D-GaIN) and lipopolysaccharide (LPS). Their splenic microarchitecture is disorganized, characterized by the loss of the clearly defined marginal zone, ill defined T and B cell areas, and absence of MAdCAM-1 and reduced ICAM-1, VCAM-1 and Mac-1 expression. They are devoid of peripheral lymph nodes and Peyer's patches, and show a strong reduction of IgA+ plasma cells in the intestinal lamina propria. The alymphoplasia is accompanied by a marked B lymphocytosis and reduced basal lg levels. Ig depositions in the renal glomerulus and a strong up-regulation of MHC class I antigen expression on endothelial cells of different tissues are observed. The primary humoral immune response towards sheep red blood cells reveals a defective IgG isotype switch, while that against vesicular stomatitis virus is normal. The cytotoxic T cell responses are attenuated, although still effective, against vaccinia, lymphocytic choriomeningitis virus (LCMV-ARM) and LCMV-WE. In conclusion, the combined inactivation of Tnf and Ltalpha confirms their essential role in the normal development and function of the immune system.

Animals↗
PubMed1996

Influence of different volume therapies and pentoxifylline infusion on circulating soluble adhesion molecules in critically ill patients.

OBJECTIVE: To study the influence of long-term volume therapy with different solutions and continuous administration of pentoxifylline on plasma concentrations of circulating adhesion molecules. DESIGN: Prospective, randomized study. SETTING: A surgical intensive care unit (ICU) of a university hospital. PATIENTS: Forty-two patients with sepsis secondary to major surgery were included. INTERVENTIONS: The patients were randomly separated into three groups. In group 1 (n=14), volume therapy was exclusively carried out with 10% low-molecular-weight hydroxyethyl starch solution. In group 2 (n=14), patients exclusively received 20% human albumin for volume therapy. In group 3 (n=14), volume therapy was not defined and pentoxifylline was continuously given (1.4 mg/kg/hr iv). MEASUREMENTS AND MAIN RESULTS: From arterial blood samples, plasma concentrations of soluble adhesion molecules (endothelial leukocyte adhesion molecule-1 [soluble ELAM-1], intercellular adhesion molecule-1 [soluble ICAM-1], vascular cell adhesion molecule-1 [soluble VCAM-1], and soluble granule membrane protein-140) were serially measured on the day of admission to the ICU ("baseline" value) and during the next 5 days at noon. No significant differences between the three groups were found for macrohemodynamics. Soluble ELAM-1, soluble ICAM-1 and soluble VCAM-1 plasma concentrations were markedly higher than normal values at baseline in all groups. In the hydroxyethyl starch group, soluble ELAM-1 plasma concentration decreased to the normal range, whereas it further increased in the human albumin group and was almost unchanged in the pentoxifylline group. During the study period, soluble ICAM-1 and soluble VCAM-1 plasma concentrations remained unchanged in the hydroxyethyl starch group. However, these concentrations increased in the other groups. Soluble granule membrane protein-140 increased significantly only in the human albumin group (483 +/- 103 to 683 +/- 94 ng/mL). In the hydroxyethal starch-treated patients, Acute Physiology and Chronic Health Evaluation II score decreased significantly (from 24.3 +/- 3.4 at baseline to 17.0 +/- 3.3 at the end the study period). Only PaO2/FIO2 was correlated to plasma concentrations of adhesion molecules. CONCLUSIONS: Sepsis is associated with markedly increased plasma concentrations of adhesion molecules, indicating endothelial activation or damage. By long-term volume therapy with hydroxyethal starch solution, these concentrations remained unchanged or even decreased, whereas in patients in whom human albumin was infused or pentoxifylline was given continuously, plasma concentration of soluble adhesion molecules further increased.

Aged↗
PubMed1996

The European Organization for Research and Treatment of Cancer breast cancer-specific quality-of-life questionnaire module: first results from a three-country field study.

PURPOSE: To construct a breast cancer-specific quality-of-life questionnaire (QLQ) module to be used in conjunction with the European Organization for Research and Treatment of Cancer (EORTC) QLQ-C30 and to test its reliability and validity cross-culturally. PATIENTS AND METHODS: Module construction took place after the EORTC guidelines for module development. The module--the QLQ-BR23--consists of 23 items covering symptoms and side effects related to different treatment modalities, body image, sexuality, and future perspective. This module was tested in 170 Dutch, 168 Spanish, and 158 American cancer patients at two points in time. The timing for the Dutch and Spanish patients was before and during treatment with radiotherapy or chemotherapy. For the American patients, the questionnaire was administered at admission at the breast clinic and 3 months after the first assessment. RESULTS: Multitrait scaling analysis confirmed the hypothesized structure of four of the five scales. Cronbach's alpha coefficients were, in general, lowest in Spain (range; .46 to .94) and highest in the United States (range; .70 to .91). On the basis of known-groups comparisons, selective scales distinguished clearly between patients differing in disease stage, previous surgery, performance status, and treatment modality, according to expectation. Additionally, selective scales detected change over time as a function of changes in performance status and treatment-induced change. CONCLUSION: These results lend support to the clinical and cross-cultural validity of the QLQ-BR23 as a supplementary questionnaire for assessing specific quality-of-life issues relevant to patients with breast cancer.

Adult↗
PubMed1996

Standards for the management of swabs, needles and instruments in the operating theatre.

The management of swabs, needles and instruments in the operating theatre is a high-risk and problem-prone area for the operating theatre nurse. The purpose of this research is to formulate specific standards on the management of swabs, needles and instruments in the operating theatre to ensure the safety of the patient. An exploratory and descriptive research design was used and executed in 3 hospitals of a private hospital group in Gauteng. A structured two phase process was followed, i.e. the development phase and the validation phase. This last phase was done by means of deliberate debate. It is recommended that these standards be implemented, tested and validated on a national basis and a monitoring and evaluation system should be developed to ensure nursing compliance with these standards.

Humans↗
PubMed1996

Materiel management reengineering: value creation through innovation.

By reengineering their department's core processes, materiel managers can expand their role in the health care setting while realizing significant cost savings. Using a team model, Inova Health System materiel management staff integrated their processes for vendor selection, purchasing, inventory reduction, and utilization across three hospitals and ancillary services. An integrated approach at all levels of the organization gained buy-in from administrators and staff systemwide.

Contract Services↗
PubMed1996

[Participative management in nursing service].

The management style of the nursing service manager influences the facilitation of health, quality nursing care and quality work life of the nurses. No evidence of any research in this regard-within the context of nursing service-in South Africa could be found. The concept participative management, as well as the process (with applicable guidelines) therefore requires investigation. The purpose with this article is to isolate (identify and define) the central concepts pertaining to participative management in a nursing service, as well as the exploration and description of the process of participative management (with applicable guidelines). An exploratory, descriptive and qualitative research design was followed. Individual interviews with management experts were conducted. Content analysis of these interviews were done, as well as a literature control. A conceptual definition was formulated by inference of data, as well as the description of the process of participative management, with applicable guidelines. It is recommended that this definition be submitted to further refinement to form the foundation of a model for participative management in a nursing service. It will also be meaningful to research the costs and other implications related to participative management in a nursing service.

Decision Making, Organizational↗
PubMed1996

[Dimensions of leadership practice by nursing service managers].

Leadership development is an important component of the nursing service manager's personal and professional development. Competent leadership is required to lead the nursing service in the right direction within the context of dynamic political and social changes. Various internal and external environmental variables have a significant influence on leadership behaviour and practice. The purpose with this study is to explore and describe the characteristics or dimensions of leadership excellence by the nursing service manager. An exploratory and descriptive research design was followed and data collection was done by means of focus group interviews. The results do not show a significant difference between the knowledge already generated by research, or described in the literature, but is utilised as the basis of leadership development of nursing service managers. A leadership development programme for nursing service managers, based on the results of this study, is recommended.

Focus Groups↗
PubMed1995

Scavenging of neutrophil-derived superoxide anion by 1-hydroxyphenazine, a phenazine derivative associated with chronic Pseudomonas aeruginosa infection: relevance to cystic fibrosis.

The airways of cystic fibrosis patients colonised by Pseudomonas aeruginosa contain the redox active phenazine derivative, 1-hydroxyphenazine (OHP). As the presence of reactive oxygen species is of importance to tissue damage in cystic fibrosis, OHP was investigated for its ability to reduce molecular oxygen to superoxide. In the presence of NADPH, OHP reduced cytochrome c in a dose-dependent manner. This effect was not inhibited by superoxide dismutase and demonstrates an electron transport role for OHP. The OHP/NADPH system was unable to reduce molecular oxygen to superoxide as judged by an inability to oxidase epinephrine to adrenochrome. However, using lucigenin-enhanced chemiluminescence to detect superoxide, it was found that pathophysiologically relevant concentrations of OHP (5-25 microM) effectively scavenged superoxide from a xanthine/xanthine oxidase system. Similarly, in the presence of OHP, superoxide availability from contact-activated neutrophils was substantially reduced. It is concluded that OHP is an efficient scavenger of superoxide and that electron transfer from superoxide to OHP represents a major mechanism for reduction of OHP in vivo. Reduced OHP has the potential to alter cellular function by participating in the reduction of iron-containing proteins and in this manner contribute to the pathogenesis of P. aeruginosa infection in cystic fibrosis.

Acridines↗
PubMed1995

Expression of interleukin 8 and CD54 by human gastric epithelium after Helicobacter pylori infection in vitro.

BACKGROUND/AIMS: Helicobacter pylori is associated with neutrophil infiltrates, although the mechanism of their recruitment is only partially defined. The aim of the study was to determine if Kato III, a human gastric epithelial cell line, expressed cytokines and the intercellular adhesion molecule 1 (ICAM-1), which could contribute to the initiation of inflammation during infection with H. pylori. METHODS: Kato III cells were stimulated with H. pylori and were examined for evidence of infection, cytokine production, and the expression of ICAM-1. RESULTS: The expression of interleukin 8 messenger RNA and immunoreactive protein by Kato III cells was significantly increased over constitutive levels within 3 hours of infection with H. pylori. Infected Kato III supernatants activated neutrophils as evidenced by increased CD11b/CD18 and decreased L-selectin that could be blocked by anti-interleukin 8. In contrast, Campylobacter jejuni, lipopolysaccharide, killed H. pylori, and supernatants from cultures of H. pylori did not increase interleukin 8. Interleukins 2 and 6; interferons alfa, beta, and gamma; and tumor necrosis factor were not produced by resting or H. pylori-stimulated Kato III cells. In addition to producing interleukin 8, Kato III constitutively expressed surface ICAM-1, which acts as an intercellular adhesion molecule for neutrophils. CONCLUSIONS: Our results indicate that H. pylori stimulates the gastric epithelium to initiate inflammation and neutrophil recruitment and activation.

Base Sequence↗
PubMed1995

Characterization of a pineal region malignant rhabdoid tumor. Towards understanding brain tumor cell invasion.

The malignant rhabdoid tumor (MRT) of the central nervous system is a highly aggressive neoplasm of early infancy which is characterized by brain invasion and widespread dissemination along cerebrospinal fluid pathways. As the process of tumor invasion is mediated in part by the elaboration of proteases and protease inhibitors by tumor cells, we sought to determine the expression of the type-IV collagenases and their inhibitors (tissue inhibitors of metalloproteases, TIMPs) in an MRT from the pineal region of a 9-month-old male. In addition, as only a few reports exist concerning the cytogenetic abnormalities in MRTs, the cytogenetic features of this MRT were examined. When placed into tissue culture, the MRT grew vigorously in early passages. The cytogenetic analysis of the cells in passage one revealed a near diploid karyotype with some metaphases demonstrating monosomy 22. Northern analysis of type-IV collagenase transcripts revealed that the MRT expressed the highest levels of the 72- and 92-kD type-IV collagenase transcripts of any pediatric brain tumor examined. However, the MRT did not express any significant amounts of the TIMP-1 or TIMP-2 transcripts. By in situ hybridization analysis, the MRT demonstrated marked intratumoral expression of the type-IV collagenase but not TIMP transcripts. The results from this study suggest that this particular MRT may be a highly invasive brain tumor, at least in part on the basis of overexpression of the type-IV collagenases relative to the TIMPs.

Biomarkers, Tumor↗