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Biomedical subjects

M Muller

Publications and source records attributed to M Muller.

At least 145 records · Page 8Linked to original sources
PubMed1997

The glucocorticoid receptor inhibits the human prolactin gene expression by interference with Pit-1 activity.

Glucocorticoids have been shown to inhibit the activity of the human prolactin (hPRL) promoter. Using transient expression experiments in rat pituitary cells, we located the sequence conferring glucocorticoid inhibition to a region which contains Pit-1 binding sites, responsible for pituitary-specific expression, but does not seem to contain a glucocorticoid receptor (GR) binding site. Co-transfection experiments in non-pituitary cell lines, using expression vectors for Pit-1 and different mutants of the human GR show that inhibition of the hPRL gene is seen only in the presence of Pit-1 and GR, and that the DNA binding function of the receptor is not required. Immunoprecipitation studies show that either anti-GR or anti-Pit-1 antibodies are able to co-precipitate GR and Pit-1, suggesting an interaction between these factors. We conclude that the activated GR functionally interferes with the pituitary specific factor Pit-1, thereby leading to the observed transcriptional repression.

Animals↗
PubMed1997

Pathological changes in pancreatic ducts from patients with chronic pancreatitis.

CONCLUSION: Chronic pancreatitis and restricted pancreatic outflow are accompanied by pathological changes in the ducts, including inflammation and alterations in the microvasculature. These changes and loss of epithelium provide a likely explanation for increased release of serum proteins, immunoglobulins, and lactoferrin into the juice, and the possibility of luminal contents entering the extracellular space and bloodstream. BACKGROUND: Enlargement of pancreatic ducts is a well-known phenomenon accompanying chronic pancreatitis and conditions restricting outflow of pancreatic juice. However, the relationship between ductal pathology and concomitant changes in the pancreatic juice is incompletely understood. METHODS: Segments of pancreatic ducts removed at surgery from patients with chronic pancreatitis and conditions restricting outflow were studied by light and electron microscopy to assess the pathological changes. RESULTS: Pathological changes in ducts from patients with chronic pancreatitis include chronic inflammation in the wall, enlarged and numerous capillaries packed with erythrocytes and leukocytes close to the lumen, and loss of epithelium and sometimes basement membrane. Plasma cells provide a source for increased immunoglobulins. Ducts from patients with diseases restricting outflow show significant pathology.

Case-Control Studies↗
PubMed1997

Oxidative stress and the mobilisation of arachidonic acid in stimulated human platelets: role of hydroxyl radical.

Platelet functions, including eicosanoid biosynthesis, can be significantly altered by exposure to reactive oxygen species. We utilised the redox properties of the phenazine derivative, pyocyanin, to generate low micromolar levels of reactive oxygen species in order to investigate the metabolism of arachidonic acid by human platelets under oxidative stress. Eicosanoid production by platelets, pre-labelled with [3H]arachidonic acid (AA) and stimulated with the calcium ionophore A23187, was inhibited in the presence of pyocyanin. In contrast, platelets pre-treated with pyocyanin and concurrently exposed to A23187 and AA showed no evidence of inhibition. Analysis of the free label content of labelled, pyocyanin-treated platelets after stimulation revealed diminished levels of total free label and a corresponding increase in labelled phospholipid. Prior treatment with the antioxidants, superoxide dismutase, catalase or the hydroxyl radical scavenger, mannitol, before the addition of pyocyanin afforded protection against loss of eicosanoid production and restored AA release. We conclude that hydroxyl radicals inhibit one or more steps in the cascade leading to phospholipase A2 activation and release of arachidonic acid from platelet phospholipid stores.

Antioxidants↗
PubMed1997

Self-inflicted burns.

Self-inflicted burns are a regular source of admissions to burns units world wide. This study examines the characteristics and outcomes of those who deliberately burn themselves. The medical records of all patients admitted to the Royal Brisbane Hospital Burns Unit and identified as having suffered a self-inflicted burn between 1990 and 1995 were reviewed. The records of patients who doused themselves with flammable liquid between 1984 and 1995 were examined as a separate group. Of 1072 admissions there were 44 cases (4.1 per cent) of deliberately self-inflicted burns. Average age was 30 yr with an average total burn surface area (TBSA) of 30 per cent (range 1-98 per cent). Schizophrenia, depression and personality disorder were diagnosed in 71 per cent. Alcohol intoxication was common in the rest. Suicide attempters were almost all male and the majority (60 per cent) were diagnosed with a major psychiatric illness. Self-mutilators suffered much less serious burns and none died. Self-inflicted burns accounted for 24 per cent of burns admitted to the intensive care unit. Self-immolation with flammable liquid resulted in severe burns with a 45 per cent mortality. A number of differences was demonstrated between those patients who had attempted suicide and those who had deliberately burnt themselves without suicidal attempt. Self-immolators constitute a considerable proportion of major burns admitted to this unit.

Adolescent↗
PubMed1997

Silvazine (silver sulfadiazine and chlorhexidine) activity against 200 clinical isolates.

The study was undertaken to examine the in vitro efficacy of Silvazine against micro-organisms commonly found in burn wounds. Two hundred non-replicative sequential clinical isolates were collected over a 2-month period. These comprised 50 Staphylococcus aureus (methicillin sensitive), 50 Staphylococcus aureus (methicillin resistant), 50 coagulase negative staphylococci and 50 Pseudomonas aeruginosa. As there is no standard test method, the method chosen was a pour plate overlay of micro-organisms placed on a Mueller Hinton base containing duplicate wells of 0.1 ml Silvazine. Plates were incubated at 35 degrees C for up to 48 h prior to examination. All organisms tested showed zones of growth inhibition. The mean diameters of the zones of growth inhibition were similar within genera. S. aureus 19.7 +/- 1.6 mm, MRSA 16.9 +/- 1.6 mm, P.aeruginosa 15.3 +/- 1.1 mm and coagulase negative staphylococci 20.8 +/- 2.1 mm. There was no bacterial regrowth within the zones of growth inhibition following long-term plate storage. In vitro testing of Silvazine has confirmed its efficiency against common burn wound isolates.

Anti-Infective Agents, Local↗
PubMed1997

Effect of neurological dysfunction on health-related quality of life in patients with high-grade glioma.

The purpose of the study was to assess health-related quality of life (HQL) in patients with high-grade malignant glioma of the brain. The EORTC core Quality of Life Questionnaire (QLQ-C30) and a Brain Cancer Module (BCM20) were administered at baseline and several weeks later (follow-up) to 105 patients with either recently-diagnosed (n = 41) or recurrent (n = 64) malignant glioma. In addition, the attending neurologists completed a standard neurological examination, a modified Barthel Activities of Daily Living Index (BADLI) and the Karnofsky Performance Scale (KPS). In a preliminary step, the QLQ-C30 was found to have acceptable reliability (internal consistency and test-retest reliability). Newly-diagnosed patients and those with a KPS of 80-100 had significantly better physical, role and cognitive functioning and global quality of life with less fatigue, visual disorder, motor dysfunction, communication deficit, weakness of both legs and trouble controlling the bladder than did those with recurrent disease and those with a KPS of 50-70. Similarly, those capable of independent activities of daily living, as reported on the BADLI, had higher functioning scores and less fatigue than did those who were not independent. Patients with dysphasia, mental confusion or motor deficit on neurological examination reported significantly lower levels of physical, role, cognitive, emotional and social functioning and global quality of life than did patients not having these difficulties. They also had significantly more symptoms. In patients with deteriorating neurological status between baseline and follow-up, there was a marked decline in cognitive, physical, role, emotional and social functioning and global quality of life and an increase in fatigue. Thus, there are significant differences in HQL between patients with newly-diagnosed and recurrent brain cancer and between patients with differing KPS and BADLI scores. In addition, the HQL scores provide details not provided by the KPS and the BADLI. Deterioration in neurological function is accompanied by significant deterioration in a range of HQL domains and in global quality of life.

Adolescent↗
PubMed1997

Resistance of TNF/LT alpha double deficient mice to bleomycin-induced fibrosis.

In order to evaluate the role and mode of action of TNF in bleomycin-induced lung fibrosis, mice deficient for TNF and LT alpha (delta TNF/LT alpha) were examined at 2 months of age and after 3 weekly i.v. injections of bleomycin. The body weight of the delta TNF/LT alpha mice was 88 +/- 11% of that of the wild type littermates. Lung collagen, evaluated by its hydroxyproline content, was also lower (81 +/- 9%) in mutant than in wild type littermates. Bleomycin induced a diffuse alveolitis with focal areas of alveolar remodelling in wild type but not in delta TNF/LT alpha, mice. Lymphoid infiltration was also prominent in wild type, but absent from delta TNF/LT alpha, mice. Bleomycin injections increased collagen deposition, as evaluated by the lung hydroxyproline content, more markedly in wild type, than in delta TNF/LT alpha, mice. Cell trapping in the alveolar capillaries was evaluated by semi-quantitative electron microscopy. Bleomycin markedly increased platelet trapping in the alveolar capillaries of wild type, but not of delta TNF/LT alpha, mice. This study indicates that the expression of TNF/LT alpha genes increases the deposition of collagen in both untreated and inflamed lung and that these genes may act, at least in part, by promoting platelet trapping.

Animals↗
PubMed1997

A Polycomb and GAGA dependent silencer adjoins the Fab-7 boundary in the Drosophila bithorax complex.

The homeotic genes of the Drosophila bithorax complex are controlled by a large cis-regulatory region that ensures their segmentally restricted pattern of expression. A deletion that removes the Frontabdominal-7 cis-regulatory region (Fab-7') dominantly transforms parasegment 11 into parasegment 12. Previous studies suggested that removal of a domain boundary element on the proximal side of Fab-7' is responsible for this gain-of-function phenotype. In this article we demonstrate that the Fab-7' deletion also removes a silencer element, the iab-7 PRE, which maps to a different DNA segment and plays a different role in regulating parasegment-specific expression patterns of the Abd-B gene. The iab-7 PRE mediates pairing-sensitive silencing of mini-white, and can maintain the segmentally restricted expression pattern of a BXD, Ubx/lacZ reporter transgene. Both silencing activities depend upon Polycomb Group proteins. Pairing-sensitive silencing is relieved by removing the transvection protein Zeste, but is enhanced in a novel pairing-independent manner by the zeste' allele. The iab-7 PRE silencer is contained within a 0.8-kb fragment that spans a nuclease hypersensitive site, and silencing appears to depend on the chromatin remodeling protein, the GAGA factor.

Alleles↗
PubMed1997

Phospholipase activity in Cryptococcus neoformans: a new virulence factor?

Fifty isolates of Cryptococcus neoformans were examined for extracellular phospholipase production after inoculation onto egg yolk agar; 49 produced a pericolonial precipitate indicative of phospholipase activity. Phospholipase B (PLB), lysophospholipase, and lysophospholipase-transacylase activities were identified by radiometric analysis in supernatants from 4 clinical isolates. The ratio of colony diameter to colony plus precipitate on agar (Pz) correlated with PLB activity. Phospholipase production was similar in 12 environmental and 13 clinical isolates of C. neoformans var. gattii. Environmental strains of C. neoformans var. neoformans (n = 8) produced more phospholipase at 72 h than did 17 clinical isolates (mean Pz, 0.57 vs. 0.72; P < .01); however, Pz values were similar at 96 h. Quantitation of cryptococci in the lungs and brains of BALB/c mice inoculated intravenously with 4 strains expressing high, intermediate, or low phospholipase activity revealed a correlation between phospholipase activity and virulence. Phospholipases secreted by C. neoformans may be implicated in virulence.

Acyltransferases↗
PubMed1997

Identification of extracellular phospholipase B, lysophospholipase, and acyltransferase produced by Cryptococcus neoformans.

We recently identified phospholipase activity as a potential virulence factor of Cryptococcus neoformans. We have now defined the nature of the phospholipase activity produced by a clinical isolate of C. neoformans var. neoformans, under native conditions, by 1H and 31P nuclear magnetic resonance (NMR) spectroscopy and thin-layer chromatography (TLC) of radiolabelled substrates. Glycerophosphocholine was identified by NMR spectroscopy as the sole phospholipid degradation product of the reaction between substrate phosphatidylcholine (PC) and cryptococcal culture supernatants indicating the presence of phospholipase B (PLB). No lysophosphatidylcholine (lyso-PC) or products indicative of phospholipase C, phospholipase D, or other lipase activity were identified. Use of PC and lyso-PC containing radiolabelled acyl chains and separation of products by TLC confirmed the PLB and lysophospholipase (LPL) activities. Lysophospholipase transacylase (LPTA) activity was identified by the formation of radioactive PC from lyso-PC. Extracellular enzyme production was maximal after 6 to 10 h in fresh medium. Assay conditions were optimized for pH, linearity with time, enzyme concentration, and saturation by substrates to allow comparison with phospholipases from other organisms. LPL activity was 10- to 20-fold greater than PLB activity, with mean (+/- standard deviation) specific activities of 34.9 +/- 7.9 and 3.18 +/- 0.2 micromol of substrate hydrolyzed per min per mg of protein, respectively. The response of PLB to increasing substrate concentrations was bimodal, whereas inhibition of LPL and LPTA activities occurred at concentrations of substrate lyso-PC greater than 200 microM. Enzyme activities were stable at acid pH (3.8), with pH optima of 3.5 to 4.5. Activities were unchanged in the presence of exogenous serine protease inhibitors, divalent cations, and EDTA. We conclude that C. neoformans produces highly active extracellular PLB, LPL, and LPTA under native conditions.

Acyltransferases↗
PubMed1997

Modulation of neutrophil superoxide response and intracellular diacylglyceride levels by the bacterial pigment pyocyanin.

Low concentrations of pyocyanin are reported to enhance superoxide production by human neutrophils exposed to various stimuli, yet the mechanism remains unknown. Using lucigenin-enhanced chemiluminescence, we examined the kinetics of the neutrophil superoxide response in the presence of pyocyanin. At all concentrations (12.5 to 200 microM), pyocyanin decreased the peak superoxide response while prolonging the duration of the response. The prolonged response may be associated with an observed increase in intracellular diacylglyceride levels due to pyocyanin exposure.

Diglycerides↗
PubMed1997

At least three subdomains of v-erbA are involved in its silencing function.

Several members of the thyroid hormone receptor (TR) family are able to switch from a transcriptional repressor to a transcriptional activator upon binding of their ligand. The oncogene v-erbA is a variant form of the TR unable to bind hormone and thus acts as a constitutive repressor. We demonstrate, using fusion proteins between the DNA-binding domain of the yeast factor GAL4 and the silencing domains of v-erbA and TR beta, that point mutations in three different regions severely affect their repression function. Furthermore, the three regions, each as an inactive fusion protein with the GAL4 DNA-binding domain, restore silencing activity when assembled on the same promoter. These observations define at least three silencing subdomains, SSD1-SSD3, which are involved in the silencing function of v-erbA. We propose a model in which full silencing activity is brought about by the combined interaction of each silencing subdomain with corepressors and/or basal transcription factors.

Amino Acid Sequence↗
PubMed1997

Thyroid hormone inhibits the human prolactin gene promoter by interfering with activating protein-1 and estrogen stimulations.

Transcription of the human PRL (hPRL) gene in the pituitary is subject to tissue-specific and multihormonal regulation involving two main regulatory regions, a proximal promoter and a distal enhancer. In this report we show that thyroid hormone inhibits the expression of the hPRL gene in rat pituitary cells. Transient expression experiments show that thyroid hormone regulation involves a strong inhibitory element, located in the proximal (-164/-35) promoter, which is modulated by a more distal stimulatory response control region. Gel retardation experiments reveal that the thyroid hormone receptor does not bind to the proximal negative element. We show the existence of an activating protein-1 (AP-1) response element located at positions -61 to -54 of the proximal promoter, conferring AP-1 stimulation to the hPRL promoter. This AP-1 induction is abolished when hormone-bound thyroid hormone receptor is present, indicating that there is an interference between the thyroid hormone receptor and AP-1 regulatory pathways. Furthermore, using the complete hPRL upstream region, we show that estrogen induction is abolished by simultaneous thyroid hormone treatment.

Animals↗
PubMed1997

A one-nucleotide difference in a cAMP and phorbol ester response element leads to differential regulation of the human chorionic somatomammotropin A and B gene transcription.

Human chorionic somatomammotropin (hCS) is encoded by two highly related genes, hCS-A and hCS-B, located in the hGH/hCS gene locus. Both genes are expressed in the syncytiotrophoblast layer of the placenta and hCS release from trophoblast cells is known to be increased by cAMP and phorbol esters. However, it remains unclear whether this regulation acts at the level of hCS gene expression or secretion and whether both genes are affected. We examined the effects of cAMP and phorbol 12-myristate 13-acetate (PMA) on the transcription of the hCS-A and hCS-B genes. Transient expression experiments revealed a 7 bp cAMP- and PMA-responsive element (CRElhCS-A) spanning nucleotides-1102 to -1096 upstream of the hCS-A gene. In contrast, the homologous sequence upstream of hCS-B (CRElhCS-B), differing from CRElhCS-A by a single substitution, shows little or no response to cAMP. In band-shift assays, the CRElhCS-A oligonucleotide was shown to bind two factors related to CREBP and AP-1, whereas CRElhCS-B only competes for one of these complexes. Finally, Southwestern analysis revealed that the CRElhCS-A element binds two ubiquitous proteins of 100 kDa and 47 kDa respectively, whereas CRElhCS-B interacts only with the 47 kDa protein. Taken together, these results suggest that a 47 kDa protein binding to the CRElhCS-A and CRElhCS-B elements is involved in the PMA response of the hCS-A and hCS-B genes, and a 100 kDa protein plays a crucial role in cAMP regulation of the hCS-A gene.

Cell Line↗
PubMed1997

Valsartan, a new angiotensin II antagonist; blood pressure reduction in essential hypertension compared with an angiotensin converting enzyme inhibitor, enalapril.

OBJECTIVE: To compare the blood pressure reduction induced by valsartan, a new angiotensin II receptor antagonist, with that induced by enalapril, an angiotensin converting enzyme (ACE) inhibitor in essential hypertension. METHODS: In total 189 adult outpatients with uncomplicated essential hypertension participated in this double-blind study. Patients were allocated randomly in equal numbers to be administered 80 mg valsartan or 20 mg enalapril daily for 12 weeks. Patients whose blood pressure had not been controlled adequately despite 8 weeks of monotherapy were administered additional therapy with 12.5 mg hydroclorothiazide (HCTZ) daily thereafter. Patients were assessed aftger 4, 8 and 12 weeks of therapy. The primary efficacy variable was the change from baseline in mean sitting diastolic blood pressure (SDBP) after 8 weeks of therapy. Other variables analyzed included the change in sitting systolic blood pressure and percentage responses after 8 weeks of therapy. RESULTS: Valsartan and enalapril were both effective at lowering the blood pressure. Similar falls were induced in the two groups with a similar time course of blood pressure reduction. The mean decreases in SDBP after 8 weeks of therapy were 13.2 mmHg for valsartan and 12.0 mmHg for enalapril. There was no significant difference between the treatments [P = 0.475, 95% confidence interval of the estimated difference (SBP after therapy - SDBP before therapy) -3.5 to 1.6 mmHg]. After 8 weeks of therapy 60.6% had responded to valsartan and 52.6% to enalapril (P = 0.267). Both treatments were tolerated well. Three patients administered enalapril and one patient administered valsartan discontinued their treatment because it made them cough. CONCLUSION: The data show that 80 mg valsartan is as effective as 20 mg enalapril in the treatment of moderate hypertension and that it is tolerated well.

Journal Article↗
PubMed1997

[Development of leadership in a nursing college].

This study is conducted within the context of nursing colleges and focuses on the empowerment of educational staff in a nursing college to facilitate excellence in leadership practice. A qualitative exploratory and descriptive study was conducted in different phases: the views and expectations of educational staff as leaders, as well as the views and expectations of the fourth year students as followers and potential professional leaders were explored and described by means of focus group interviews. A provisional conceptual framework for leadership development in a nursing college was compiled, exposed to a literature control and a final conceptual framework was refined, together with guidelines for leadership development in a nursing college. This article focuses on the final conceptual framework as well as the programme for leadership development in a nursing college. It is recommended that this programme be implemented and exposed to purposeful evaluation.

Curriculum↗