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Biomedical subjects

M J Stewart

Publications and source records attributed to M J Stewart.

At least 109 records · Page 6Linked to original sources
PubMed1992

Gene transfer in vivo with DNA-liposome complexes: safety and acute toxicity in mice.

DNA can be introduced into a variety of cell types after formation of liposomal complexes with cationic lipids. In this report, conditions have been established to optimize the production of DNA-liposome complexes that efficiently transfect cells. The safety and toxicity of this method of gene delivery have been assessed after in vivo administration, either by intravenous or direct intratumor injection. Nine to eleven days after intravenous injection, DNA was found primarily in heart and lung tissue by PCR analysis. No abnormalities were evident from histologic examination of tissue, examination of tissue-specific serum enzymes, routine biochemical parameters, or electrocardiographic monitoring. DNA-liposome complexes can therefore be used for the delivery of recombinant genes in vivo with minimal toxicity.

Animals↗
PubMed1992

Dilated cardiomyopathy associated with chronic overuse of an adrenaline inhaler.

Endogenous catecholamines in excess are known to cause dilated cardiomyopathy. A patient presented with dilated cardiomyopathy after many years of overusing an adrenaline inhaler. Pathological features and a considerable improvement in myocardial function after withdrawal implicated the exogenous catecholamine excess in the pathogenesis of the cardiomyopathy.

Adult↗
PubMed1992

Laxative induced diarrhoea--a neglected diagnosis.

A laxative screening service was established and offered to gastroenterologists in hospitals covering the West and Central belt of Scotland. The prevalence of laxative induced diarrhoea was assessed in two populations and was found to be 4% in new patients presenting to a gastroenterology clinic with diarrhoea and 20% in patients already under investigation of chronic idiopathic diarrhoea. A high rate of missed diagnosis of laxative induced diarrhoea (71%) and a low request rate (eight per annum) confirm the low clinical awareness of this diagnosis. We found potential savings of 80% of the cost of investigations subsequently ordered which could have been avoided by performing laxative screens on all patients presenting with diarrhoea. The introduction of such a screening policy is recommended as a cost-effective measure.

Cathartics↗
PubMed1992

Measurement of faecal ammonia.

A modified end-point enzymatic method for the measurement of ammonia in stool water is presented. A protein precipitation step was included in order to inactivate urease and faecal enzymes, which oxidise NADH. The modified method is reliable, with acceptable precision and accuracy, and is linear up to a concentration of 1.5 mmol/l.

Ammonia↗
PubMed1991

The role of CCAAT/enhancer-binding protein in the differential transcriptional regulation of a family of human liver alcohol dehydrogenase genes.

The transcription factor CCAAT/enhancer-binding protein (C/EBP) was found to selectively trans-activate one member of the human class I alcohol dehydrogenase (ADH) gene family. A comparison of the promoters for the three human class I ADH genes ADH1, ADH2, and ADH3 indicated a very similar pattern of binding sites (sites A-F) for rat liver nuclear proteins located between -10 and -210 base pairs (bp). In all three promoters site A consisted of two binding sites for the transcription factor C/EBP closely flanking both sides of the TATA box, but C/EBP bound with much greater affinity to site A of ADH2. C/EBP also bound at two locations which coincide with site D (-120 bp) and site E (-160 bp) of all three promoters. Cotransfection studies of human hepatoma cells using ADH-cat fusions and a C/EBP expression plasmid indicated that the human ADH2 promoter responded well to C/EBP trans-activation whereas the human ADH1 and ADH3 promoters, which bind C/EBP weakly, responded poorly. Individual mutations in several ADH2 nuclear factor-binding sites allowed the identification of four functional C/EBP-binding sites, i.e. two in site A as well as one each in sites D and E. Also, the ADH2 TATA box was found to be dispensable for C/EBP induction. Compared to ADH2 and ADH3, site A in ADH1 contains four extra base pairs between the two C/EBP motifs, and deletion of these nucleotides increased the C/EBP responsiveness of ADH1 presumably by changing the spacing of the two C/EBP motifs. Thus, sequence divergence of human class I ADH gene family members has led to forms which vary in their responsiveness to C/EBP. We suggest that C/EBP contributes to liver-specific expression of the human class I ADH gene family by selectively inducing the ADH2 gene via a TATA-independent mechanism during liver development.

Alcohol Dehydrogenase↗
PubMed1991

Retinoic acid response element in the human alcohol dehydrogenase gene ADH3: implications for regulation of retinoic acid synthesis.

Retinoic acid regulation of one member of the human class I alcohol dehydrogenase (ADH) gene family was demonstrated, suggesting that the retinol dehydrogenase function of ADH may play a regulatory role in the biosynthetic pathway for retinoic acid. Promoter activity of human ADH3, but not ADH1 or ADH2, was shown to be activated by retinoic acid in transient transfection assays of Hep3B human hepatoma cells. Deletion mapping experiments identified a region in the ADH3 promoter located between -328 and -272 bp which confers retinoic acid activation. This region was also demonstrated to confer retinoic acid responsiveness on the ADH1 and ADH2 genes in heterologous promoter fusions. Within a 34-bp stretch, the ADH3 retinoic acid response element (RARE) contains two TGACC motifs and one TGAAC motif, both of which exist in RAREs controlling other genes. A block mutation of the TGACC sequence located at -289 to -285 bp eliminated the retinoic acid response. As assayed by gel shift DNA binding studies, the RARE region (-328 to -272 bp) of ADH3 bound the human retinoic acid receptor beta (RAR beta) and was competed for by DNA containing a RARE present in the gene encoding RAR beta. Since ADH catalyzes the conversion of retinol to retinal, which can be further converted to retinoic acid by aldehyde dehydrogenase, these results suggest that retinoic acid activation of ADH3 constitutes a positive feedback loop regulating retinoic acid synthesis.

Base Sequence↗
PubMed1991

Assessment of theophylline compliance in general practice using a 'compliance index' based on apparent drug clearance.

The monitoring of compliance in outpatients using serum drug levels suffers from the difficulty of relating concentrations to changes in dosage. Clearance is independent of dose for most drugs, and may be predicted using a Bayesian based forecasting program. This paper describes how the apparent clearance obtained following a single drug analysis can be compared with the Bayesian population value to derive a Compliance Index. In compliant individuals with stable hepatic and renal function this index should remain constant. We evaluated the usefulness of the Compliance Index in general practice with patients prescribed theophylline. Of 54 patients examined on up to five occasions, only 12% were deemed to be fully compliant at all times. Compliance improved during the study, but worsened again once regular consultation ceased. The results indicate that such a Compliance Index is a viable method of assessing compliance with the aid of concentration measurements.

Adolescent↗
PubMed1991

Diagnosis of the abuse of magnesium and stimulant laxatives.

A reliable diagnosis of laxative abuse can only be reached by chemical analysis. We report a modified thin layer chromatography approach for the detection and confirmation of over-the-counter colonic stimulant laxatives. Potential interference by dietary and drug components chemically similar to anthraquinones was investigated and the method was found to be specific in this respect. The diagnosis of magnesium laxative abuse is more difficult since magnesium is a component of body fluids. By inducing diarrhoea with magnesium salts in volunteers we have established that the diagnosis can be made by measuring magnesium concentrations in stool water, with 30 mmol/L being an appropriate cut-off concentration.

Cathartics↗
PubMed1991

Ambulatory blood pressure monitoring in secondary hypertension.

The term 'secondary hypertension' includes a variety of aetiological processes with no obvious common feature apart, perhaps, from the loss of normal blood pressure regulatory factors. It has been suggested that all forms of secondary hypertension, including renal/renovascular, accelerated phase, glucocorticoid and mineralocorticoid excess, phaeochromocytoma and toxaemia in pregnancy are associated with the loss of the normal nocturnal fall in blood pressure. The evidence for this view appears strongest for glucocorticoid-induced hypertension, but for most other forms the available data are conflicting and are mostly based on small numbers of patients without adequate control populations. Sleep is a powerful determinant of the nocturnal fall in blood pressure but few studies have addressed the quality of sleep in groups of patients who are often sick and/or hospitalized. Abnormalities in sympathetic drive (e.g. autonomic neuropathy and phaeochromocytoma) can abolish the nocturnal blood pressure reductions, and activation of the sympathetic nervous system may be a critical factor in determining the normal diurnal changes in blood pressure. As approximately 20% of patients with 'essential hypertension' have a blunted fall in nocturnal blood pressure it seems unlikely that ambulatory blood pressure could ever be useful in screening for secondary hypertension.

Adrenal Gland Neoplasms↗
PubMed1990

The effect of doxorubicin on the glutathione content and viability of cultured human lung cancer cell lines A549 and GLC4 210.

Glutathione was measured in doxorubicin-sensitive cells from small cell carcinoma of lung (GLC4 210), and the levels compared with those of cells with acquired resistance and a line of resistant non-small-cell adenocarcinoma A549 (Alveolar type 2). The effect of different doxorubicin concentrations on glutathione were measured by HPLC. The effect of doxorubicin on the viability of the cell lines was studied using thiazole blue dye reduction. An increase in A549 sensitivity to doxorubicin was produced using buthionine-S,R-sulfoximine at a non-toxic dose.

Adenocarcinoma↗
PubMed1990

A hormone response element upstream from the human alcohol dehydrogenase gene ADH2 consists of three tandem glucocorticoid receptor binding sites.

The 5'-flanking region of the human gene encoding beta-alcohol dehydrogenase (ADH2) was shown by DNase I footprinting to contain three tandem binding sites for purified glucocorticoid receptor. The three binding sites lie very close together between nucleotide (nt) positions -245 and -171 with respect to the transcription start point. DNase I footprinting using a rat liver nuclear extract indicated a lack of protection of the glucocorticoid receptor binding sites, but protection of a sequence between nt -209 and -191 which partially overlaps the glucocorticoid receptor binding sites I and II. This site has homology with the known binding site for hepatocyte nuclear factor 1 (HNF1). ADH2 promoter DNA fragments containing various lengths of 5'-flanking sequences were fused upstream from the gene encoding chloramphenicol acetyltransferase (cat) and transfected into the HepG2 human hepatoma cell line. The resulting cat expression was subject to induction by dexamethasone in constructions containing ADH2 DNA between nt -272 and -171. This indicates that the glucocorticoid receptor binding sites identified by footprint analysis function as a glucocorticoid response element (GRE) in a liver cell line. Heterologous ADH-cat fusions, in which the ADH2-GRE was fused to the adenovirus major late promoter, exhibited glucocorticoid induction of cat expression in CV-1B cells when cotransfected with a glucocorticoid receptor expression vector. Glucocorticoid regulation in CV-1B was observed when either all three glucocorticoid receptor binding sites (sites 0, I, II) or the two distal sites (sites 0, I) were present. Overall, these results indicate that the ADH2 gene possesses a functional GRE which can potentially regulate expression transcriptionally.(ABSTRACT TRUNCATED AT 250 WORDS)

Alcohol Dehydrogenase↗
PubMed1990

Promoters for the human alcohol dehydrogenase genes ADH1, ADH2, and ADH3: interaction of CCAAT/enhancer-binding protein with elements flanking the ADH2 TATA box.

The human ADH1, ADH2, and ADH3 genes are closely related members of a gene family which are differentially expressed during liver development. To begin examining the mechanism of this tissue-specific and stage-specific expression, the 5'-flanking nucleotide (nt) sequences of the three genes were determined and the transcription start point (tsp) were identified. Sequences of all three genes indicated a high degree of homology (greater than 80% nt sequence identity) from the AUG translation start codon to about nt -780 relative to the tsp. Transient transfection assays of a set of plasmids containing various lengths of ADH 5'-flanking DNA fused to cat were performed in the HepG2 and Hep3B human hepatoma cell lines. The results indicated that the ADH2 promoter-proximal region was transcriptionally active in the absence of upstream sequences. To identify potential cis-acting elements in the ADH2 promoter-proximal region, a DNase I footprinting assay using a rat liver nuclear extract was used. Protection occurred in several locations including one, between nt -51 and -10, which shares homology with known binding sites for a previously identified rat-liver transcription factor called CCAAT/enhancer binding protein (C/EBP). Purified C/EBP was shown by footprint analysis to bind at two distinct sites in the ADH2 promoter located at nt -51 to -31 and -21 to -10. The TATA-box promoter element at nt -30 to -22 was not protected by C/EBP, but was partially protected by a factor in the rat liver nuclear extract. Thus, it is possible that the flanking C/EBP molecules may create a novel binding pocket for TFIID, the TATA-binding general transcription factor for RNA polymerase II. Alternatively, the C/EBP molecules may block access to the TATA box, and stimulate transcription of ADH2 by interacting with some component(s) other than TFIID.

Alcohol Dehydrogenase↗
PubMed1990

Toxic risks of inappropriate therapy.

Drug therapy may produce toxicity. Patient individuality or drug interactions account for many cases of poisoning, but other factors such as genetic predisposition, drug contamination or human error are also known causes. Examples of various types of drug poisoning are given, illustrating the role of the clinical chemist in minimizing or studying drug toxicity.

Drug Interactions↗
PubMed1990

Expanding theoretical conceptualizations of self-help groups.

Self-help groups, a prevalent and significant source of social support, manifest the public-participation premise of primary health care. Yet, self-help studies have typically lacked theoretical grounding. Psychoneuroimmunological and social-learning theories could contribute to the theoretical understanding of self-help groups. As self-help groups can mitigate the impact of natural social-network losses, they could help prevent health disorders via an immunocompetence-maintenance function. Health professionals could consider this possibility in assessment, planning, intervention and evaluation. Furthermore, health professionals could take steps to enhance self-efficacy and collective efficacy, derivative concepts of social-learning theory germane to self-help groups. Therefore, pertinent concepts and creative linkages are proposed in a preliminary attempt to initiate a self-help group theoretical framework for health professionals.

Humans↗