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Biomedical subjects

I Johansson

Publications and source records attributed to I Johansson.

At least 109 records · Page 6Linked to original sources
PubMed1995

Ultrarapid hydroxylation of debrisoquine in a Swedish population. Analysis of the molecular genetic basis.

Hydroxylation of debrisoquine, catalyzed by the cytochrome P450 CYP2D6 exhibits genetic polymorphism, with large inter-individual differences in metabolic capacity. About 7% of Caucasians carry deficient CYP2D6 alleles and lack the CYP2D6 enzyme (poor metabolizers). We have shown in two Swedish families, individuals carrying duplicated or amplified functional CYP2D6L-genes (CYP2D6L2), causing the opposite phenomenon, ultrarapid metabolism of debrisoquine. In the present study, the occurrence of extra copies of CYP2D6L-alleles was studied in relation to debrisoquine metabolic ratio (MR) in 270 Swedish Caucasians including 64 selected subjects with very rapid metabolism (MR < or = 0.2). Thirteen of the 64 subjects carried a duplicated CYP2D6-gene as identified by EcoRI and XbaI restriction fragment length polymorphism and allele-specific polymerase chain reaction-amplification of genomic DNA. A new allele with three active CYP2D6L-genes was identified, characterized by an XbaI 54 kilobase fragment. This indicates a preference of the CYP2D6L-gene to be amplified compared to other CYP2D6 genes. Only one subject with an MR higher than 0.2 carried the duplicated CYP2D6L-allele, also being heterozygous for the defect CYP2D6B-allele. The overall frequency of the duplicated/amplified CYP2D6-allele was about 1%, and was present in 40% of subjects with MRs < or = 0.1. Thus, other variant CYP2D6-genes may exist that cause increased CYP2D6 activity. In conclusion, a haplotype with duplicated or amplified functional CYP2D6 genes predicts, with high accuracy, ultrarapid metabolism of debrisoquine. Genotyping for this CYP2D locus variant might be of value in patients not responding to generally recommended doses of CYP2D6 substrates, to distinguish between high metabolic capacity and noncompliance.

Cytochrome P-450 CYP2D6↗
PubMed1995

Transfection of TRK-A into human neuroblastoma cells restores their ability to differentiate in response to nerve growth factor.

Human neuroblastoma cell lines frequently express the TRK-A proto-oncogene and bind nerve growth factor (NGF) but do not differentiate when exposed to NGF. Transient transfection of an exogenous TRK-A gene into SH-SY5Y and LA-N-5 neuroblastoma cells restored the ability of these tumor cells to differentiate with NGF. Stable TRK-A-transfected SH-SY5Y cell clones were isolated, and they responded to NGF by autophosphorylation of p140trk-A, c-fos induction, morphological differentiation, and increased expression of two neuronal marker genes, neuropeptide tyrosine and GAP-43. In phorbol ester-induced differentiated wild-type cells, TRK-A expression was increased with no change in NGF responsiveness. Thus, the restoration of the NGF-induced differentiation pathway by exogenous TRK-A presents a system of NGF-responsive human cultured cells and focuses attention on the trk-A protein and its function or malfunction in neuroblastoma.

Cell Differentiation↗
PubMed1994

[Binswanger disease. A blood pressure-related dementia].

Interest in Binswanger's disease has increased during the past decade, owing to the possibility of detecting white matter changes with computerised and magnetic resonance tomography. This paper consists in a summary of clinical symptoms and signs and possible diagnostic criteria, discussion of differential diagnosis, and the presentation of two own cases. Both patients manifested mild dementia and gait disturbance, and one had frequent drop attacks. Severe supra- and infra-tentorial white matter changes were present in both cases. It is important to consider a possible diagnosis of Binswanger's disease, as treatment of the appropriate risk factors may prevent or delay the development of dementia.

Aged↗
PubMed1994

Protein synthesis and mRNA in isolated growth cones from differentiating SH-SY5Y neuroblastoma cells.

The human neuroblastoma cell line, SH-SY5Y, differentiates into a neuronal, sympathetic phenotype in the presence of phorbol ester and serum. Growth cones prepared from differentiating SH-SY5Y cells have characteristics similar to those of growth cones from embryonic rat brain. In addition, SH-SY5Y growth cones contain ribosomes. In this study we show, by metabolic labeling of isolated growth cones, that local protein synthesis occurred in these structures. The pattern of labeled proteins was very similar to that of the corresponding cell body fraction. RNA was shown to be transported to the growth cone compartment, and by in situ hybridization. beta-actin mRNA could be visualized in intact neuritic growth cones. Comparison by Northern blot hybridizations of RNA prepared from growth cones and cell bodies, respectively, showed that mRNAs coding for growth-associated protein 43, microtubule-associated protein 2, actin, neuropeptide tyrosine, and glyceraldehyde-3-phosphate dehydrogenase were present in both fractions. In contrast, mRNAs coding for the nuclear proteins c-jun and N-myc were virtually absent in the growth cone, but readily detectable in the cell body preparation. The selective distribution of mRNAs to the growth cones was not restricted to stable, abundant mRNA species, since mRNA coding for the insulin-like growth factor I receptor was stable, but not present in growth cones. Thus, differentiating SH-SY5Y cells can sort and transport RNA to the growth cone compartment, suggesting that this system of clonal cells could be useful to unravel mechanisms involved in the compartmentalization of mRNA.

Blotting, Northern↗
PubMed1994

Genetic polymorphism of cytochrome P450. Functional consequences and possible relationship to disease and alcohol toxicity.

The hepatic cytochrome P450 system participates in the oxidative metabolism of numerous endogenous and exogenous compounds. In total several hundred different P450s have been cloned, but it appears that in humans only about 5-10 isoforms account for the major part of drug metabolism. Some of these are polymorphically distributed in the population. Cytochrome P450 2D6 catalyzes the oxidation of over 25 clinically important drugs, eg neuroleptics, antidepressants and lipophilic beta-blockers. Seven % of Caucasians and 1% of Orientals are defective in this enzyme and clearance of drugs metabolized by the enzyme may be substantially decreased in these individuals, with potentially increased risks for side effects caused by the drug treatment. Some individuals are ultrarapid metabolizers and do not achieve therapeutic drug levels at ordinary doses. The molecular genetic basis of these polymorphisms are presented. Methods for genotyping, which can be of predictive value for a more efficient drug therapy, are discussed. Ethanol-inducible cytochrome P450 2E1 (CYP2E1) oxidizes ethanol and acetaldehyde, in addition to over 80 toxicologically important xenobiotics. Furthermore, this isozyme produces reactive oxy radicals which are implicated in the aetiology of alcoholic liver disease. The gene is polymorphic and a mutation in a putative binding site for HNF1, described to affect gene expression, is more rare among subjects with lung cancer as compared to healthy controls. Further studies might give an answer as to whether any of the polymorphic CYP2E1 alleles is associated with the sensitivity to obtain alcoholic liver disease.

Animals↗
PubMed1994

Effect of iron-deficiency anaemia on saliva secretion rate and composition in the rat.

Iron-deficiency anaemia in man may be associated with dry mouth symptoms, such as atrophic glossitis and 'burning mouth', and a low serum iron concentration or iron-deficiency anaemia with aphthous stomatitis or non-ulcerative conditions of the oral mucosa. This study was made on one group of growing rats and another group of adult rats. The iron-deprived rats in both groups gained less weight than control rats. Saliva secretion rate was significantly lower in growing, but not in adult, iron-deprived rats than in the corresponding control groups. The activity of salivary peroxidase was significantly lower in both growing and adult rats with iron-deficiency anaemia than in their control groups. The conclusion is that iron-deficiency anaemia in the rat impairs the protection provided by the salivary peroxidase system, e.g. to hydrogen peroxide, and that saliva secretion rate may be reduced.

Anemia, Hypochromic↗
PubMed1994

A simple enzyme immunoassay for measurement of immune complex solubilization utilizing preformed peroxidase-antiperoxidase complexes.

An enzyme immunoassay (EIA) was developed for measurement of complement-mediated solubilization of immune complexes. Preformed complexes consisting of horseradish peroxidase (Pe) and anti-Pe antibodies were incubated in diluted serum. After centrifugation the soluble complexes in the supernatant were quantitated by adding peroxidase substrate followed by measurement of absorbance. Kinetic analysis of revealed significant difference between normal and EDTA-treated serum similarly to a standard assay utilising immune complexes containing radiolabelled bovine serum albumin. The difference was most pronounced after incubation of immune complexes with serum for 40 minutes. Immune complex solubilization measured by EIA was reduced in sera from 10 patients with active systemic lupus erythematosus (SLE). In serially followed patients, flares of SLE were preceded by reduction of solubilization capacity. The EIA is a simple method for determining serum capacity to solubilize preformed immune complexes and might be considered as a routine test for assessment of complement function in diseases such as SLE.

Adult↗
PubMed1994

Changes of nursing organization in a surgical department: effects on work satisfaction and quality of care.

The aim of the study was to evaluate the effects of an organizational change programme in a surgical department in Sweden (the introduction of modular nursing) on the nursing staff's perception of job satisfaction and quality of care, and to identify factors which promote or hinder this organizational change. Planning and implementation of the change programme took about 1 year and comprised structural changes and staff training. Assessments of job satisfaction and quality of care were made immediately before, and 1 year after, implementation of the change programme. Data were collected from the staff of two wards. Virtually no statistically significant changes were found when looking at the department as a whole. However, considerable differences were noted between the two wards, particularly in the following areas: relationships with colleagues, identification and commitment, and perceived quality of care. The quality of the interpersonal relationships, and the leadership of the wards' head nurses, appeared to be crucial determinants of the outcome.

Adult↗
PubMed1994

Evaluation of the prognostic value of the health assessment form among patients clinically ready for discharge.

The aim of the study was to identify patterns of physical, psychological, and social conditions that may be of prognostic value when it comes to assessing continued care of patients clinically ready for discharge; a related aim was to evaluate instruments used for this identification, especially a Swedish version of the health assessment form. The sample consisted of 53 consecutive patients (mean age 82.8 years, SD = 6.6 years) All patients came from their own homes and were admitted to surgical and orthopaedic departments. Interviews were carried out on the day the patients were assessed as medically ready for discharge, and a second time 1 month later. The health assessment form measured the persons' social and environmental situation, health history, and functional health status, and another instrument measured the persons' sense of coherence. Few significant differences in functional health status were noted between persons who could return to their homes (n = 25) and persons who were referred to institutions after discharge (n = 17). However, the persons being referred to institutions showed less favourable scores within the areas of mood, sense of coherence, and worries about their home accommodation situation. When another sub-group was included (patients who died between the interview occasions; n = 8), significant differences were also noted in the health functions breathing, digestion, elimination, and body movement. Sense of coherence had a significant prognostic value for the continued care after discharge irrespective of whether the deceased patients were included or not.

Activities of Daily Living↗
PubMed1994

Dental status, diet and cardiovascular risk factors in middle-aged people in northern Sweden.

The aim of the present study was to compare the dietary intake and the levels of traditional cardiovascular (CVD) risk factors in edentulous middle-aged individuals and individuals of the same age and sex who still had natural teeth. The study was performed within the framework of the MONICA-project. Population registers were used to sample randomly 1287 men and 1330 women aged 25-64 yr. Data were collected from a mailed questionnaire, blood analyses, registrations of blood pressure and anthropometric measures. The estimated daily energy intake did not differ between the two groups, but edentulous men and women ate more sweet snacks compared to those who still had teeth. Edentulous men also ate less fruits, vegetables and fibre and edentulous women ate more fat than dentates. Edentulous men and women were more obese and had lower serum HDL-cholesterol concentrations than those with remaining teeth. Edentulous women also had significantly higher concentrations of total cholesterol and triglycerides in serum than dentate women. Edentulous men and women were more often regular smokers, but not snuff users, than dentates of the same age and sex. Thus, the presence of two or more cardiovascular risk factors was more common in edentulous individuals than in those who still had natural teeth. In summary, these results support the hypothesis that edentulous middle-aged individuals have a more unfavourable risk factor profile for CVD. Counselling on balanced dietary habits and non-smoking given by dental personnel to orally diseased patients--recommendations given to improve resistance to dental caries or periodontitis--might therefore improve general health and possibly also improve risk factors for CVD.

Adult↗
PubMed1994

Saliva composition in Indian children with chronic protein-energy malnutrition.

The composition of paraffin-stimulated and unstimulated whole saliva was compared between two groups of 8-12-year-old Indian children-one group with severe to moderate chronic protein-energy malnutrition (PEM group) and an age- and sex-matched control group with normal protein status or mild PEM. The classification of PEM was based on anthropometric measurements compared with Indian standards. Stimulated saliva was analyzed for the following variables: electrolytes (Na+, K+, Ca2+, Cl-, and PO4(3-)), total protein, hexosamines, fucose, sialic acid, and amylase. Unstimulated saliva samples were analyzed for total protein, salivary and myeloperoxidase, thiocyanate, lactoferrin, lysozyme, a bacteria-agglutinating protein (BAGP), total IgG, total IgA, and specific anti-S. mutans IgA. The results show that the PEM group had a reduced secretion rate of stimulated but not unstimulated saliva. Further, the Ca2+ and Cl- concentrations in stimulated saliva were significantly lower in the PEM group compared with the control group, but the other electrolyte levels were similar. No differences were found in total protein concentration or glycoprotein bound carbohydrates in stimulated saliva between the two groups, but the quantity of total protein secreted per min was reduced by 20% in the PEM group. Significantly lower levels of lactoferrin, BAGP, and anti-S mutans IgA were found in unstimulated saliva from children in the PEM group, but significantly higher levels of total IgG. We conclude that children with severe or moderate PEM, who have reduced secretion rate, buffer capacity, lower Ca2+, and protein secretion in stimulated saliva, also have impaired immunological and agglutinating defense factors in unstimulated saliva.

Analysis of Variance↗
PubMed1994

Genetic analysis of the Chinese cytochrome P4502D locus: characterization of variant CYP2D6 genes present in subjects with diminished capacity for debrisoquine hydroxylation.

Cytochrome P4502D6 (CYP2D6) catalyzes the oxidative metabolism of several clinically important classes of drugs. Many of these have lower metabolic clearance rates among Chinese, compared with Caucasians, and are prescribed at lower doses for Asian patients. We have now evaluated the molecular genetic basis for this interethnic difference in drug metabolism. The CYP2D loci from two Chinese subjects, one homozygous for the XbaI 44-kilobase haplotype and one homozygous for the XbaI 29-kilobase haplotype, were cloned and characterized. Sequence analysis revealed two variant CYP2D6 genes, CYP2D6Ch1 and CYP2D6Ch2, having mutations yielding two and eight amino acid substitutions, respectively. Exon 9 of the CYP2D6Ch2 gene contained a sequence of 49 bases originating from the pseudogene CYP2D7P. In addition, mutations in the 5' flanking region common to both CYP2D6Ch genes were found. To evaluate the origin of the detrimental mutation in the genes, parts of the 5' flanking regions were introduced into a Hep G2/simian virus 40 expression system with chloramphenicol acetyltransferase as a reporter gene, and transfected cells were analyzed for activity. The ability of the upstream regions to bind nuclear factors was also evaluated using gel-shift analysis. Furthermore, several chimeric constructs of the CYP2D6wt and CYP2D6Ch genes were made, inserted into pCMV2 vectors, and expressed in COS-1 cells. A part of the upstream region of base pairs -1407 to -1068 was found to constitute an enhancer element, but the CYP2D6Ch-specific mutations did not influence the chloramphenicol acetyltransferase activity in the expression system. In contrast, expression of the chimeric genes revealed that the detrimental mutation of the CYP2D6Ch genes was C188-->T, causing a Pro34-->Ser amino acid substitution in a region that is a highly conserved in cytochromes P450 belonging to gene families 1 and 2. This substitution caused expression of a more unstable gene product, as evident from comparison of the relative levels of CYP2D6 mRNA, CYP2D6 protein, and bufuralol 1'-hydroxylase activities in pCMV2-CYP2D6-transfected COS-1 cells. Allele-specific polymerase chain reaction analysis of genomic DNA from 90 Chinese individuals revealed that the CYP2D6Ch1 allele was the most common one and its distribution correlated well with a higher metabolic ratio for debrisoquine. These data demonstrate that important interethnic differences exist in the structure of the CYP2D locus, and they suggest that the frequent distribution of the C188-->T mutation among the CYP2D6Ch genes explains the lower capacity among Chinese to metabolize drugs that are substrates of CYP2D6, such as antidepressants and neuroleptic agents.

Asian People↗
PubMed1994

Chlormethiazole as an efficient inhibitor of cytochrome P450 2E1 expression in rat liver.

Ethanol-inducible cytochrome P450 (CYP) 2E1 (CYP2E1) is responsible for the metabolism of many xenobiotics which exert toxic effects in humans. Specific inhibitors might constitute valuable tools in the elucidation of the pharmacological and toxicological roles of this isozyme in vivo. In the present investigation we have evaluated the effects of a drug used for treatment of ethanol withdrawal states, chloromethiazole (CMZ), on CYP2E1 expression in rat liver. A 4-fold induction of CYP2E1 was observed after 3 days of starvation, accompanied by a similar increase in the level of the corresponding mRNA. CMZ specifically inhibited the elevation of CYP2E1 mRNA and protein, but did not prevent CYP2B1 and CYP3A1 or CYP1A1 induction caused by treatment with phenobarbital or beta-naphthoflavone, respectively. From nuclear run-off experiments it was apparent that the rate of the CYP2E1 gene transcription was inhibited greatly by CMZ treatment. Rats treated with ethanol in a total enteral nutrition model had higher CYP2E1-dependent hepatic microsomal activities of p-nitrophenol hydroxylase and carbon tetrachloride-induced lipid peroxidation than controls, and simultaneous CMZ treatment abolished the ethanol-dependent induction. In vitro experiments with rat liver microsomes showed that CMZ did not act as an inhibitor of CYP2E1-dependent catalytic activities or as an inhibitor of microsomal NADPH and CYP2E1-dependent lipid peroxidation. In conclusion, we suggest that CMZ might constitute an efficient and specific inhibitor of CYP2E1 expression suitable for in vivo experiments.

Animals↗
PubMed1994

Activation of the human NPY gene during neuroblastoma cell differentiation: induced transcriptional activities of AP-1 and AP-2.

During functional neuronal differentiation of human SH-SY5Y neuroblastoma cells, induced by 12-O-tetradecanoylphorbol-13-acetate (TPA), the mRNA expression of c-fos and c-jun displayed a synchronous and biphasic type of induction for both mRNAs, with an early transient (30 to 120 min) and a later (> 8 h) more persistent increase. This was coupled to increased in vitro DNA binding activity of cFos/cJun AP-1 heterodimers in SH-SY5Y nuclear extracts using the electrophoretic mobility shift assay. Functional AP-1 activity was demonstrated in differentiating SH-SY5Y cells by transient transfection assays using a TPA-responsive reporter plasmid. The second expression phase of these protooncogenes was paralleled by a sustained induction of neuronal differentiation markers, as exemplified by growth-associated protein 43 and neuropeptide tyrosine (NPY) mRNAs. DNA-protein interaction between an evolutionarily conserved region (-73 to -45) of the human NPY promoter, containing potential binding sites for AP-1, AP-2, and Sp1, and nuclear extracts prepared from untreated and TPA-treated SH-SY5Y cells revealed one complex (CI) that was unaffected and three complexes (CII to CIV) that were induced by TPA treatment. Competition for DNA binding using AP-1, AP-2, and Sp1 consensus sequences and an anti-cJun antibody, respectively, revealed cooperative interactions between AP-1, AP-2, and Sp1 transcription factors and the NPY promoter. In addition, TPA-mediated induction of AP-2 DNA binding activity to the NPY promoter was not dependent on increased AP-2 mRNA expression. This high degree of complexity presumably involved in NPY gene expression during neuronal differentiation of SH-SY5Y cells suggests productive cooperative interactions between multiple transcription factors.

Base Sequence↗
PubMed1993

Inherited amplification of an active gene in the cytochrome P450 CYP2D locus as a cause of ultrarapid metabolism of debrisoquine.

Deficient hydroxylation of debrisoquine is an autosomal recessive trait that affects approximately 7% of the Caucasian population. These individuals (poor metabolizers) carry deficient CYP2D6 gene variants and have an impaired metabolism of severely commonly used drugs. The opposite phenomenon also exists, and certain individuals metabolize the drugs very rapidly, resulting in subtherapeutic plasma concentrations at normal doses. In the present study, we have investigated the molecular genetic basis for ultrarapid metabolism of debrisoquine. Restriction fragment length polymorphism analysis of the CYP2D locus in two families with very rapid metabolism of debrisoquine [metabolic ratio (MR) for debrisoquine = 0.01-0.1] revealed the variant CYP2D6 gene CYP2D6L. Eco RI RFLP and Xba I pulsed-field gel electrophoresis analyses showed that this gene had been amplified 12-fold in three members (father and his two children) of one of the families, and two copies were present among members of the other family. The CYP2D6L gene had an open reading frame and carried two mutations causing amino acid substitutions: one in exon 6, yielding an Arg-296-->Cys exchange and one in exon 9 causing Ser-486-->Thr. The MR of subjects carrying one copy of the CYP2D6L gene did not significantly differ from that of those with the wild-type gene, indicating that the structural alterations were not of importance of the catalytic properties of the gene product. Examination of the MR among subjects carrying wild-type CYP2D6, CYP2D6L, or deficient alleles revealed a relationship between the number of active genes and MR. The data show the principle of inherited amplification of an active gene. Furthermore, the finding of a specific haplotype with two or more active CYP2D6 genes allows genotyping for ultrarapid drug metabolizers. This genotyping could be of predictive value for individualized and more efficient drug therapy.

Alleles↗
PubMed1993

Genetic polymorphism of cytochrome P4502E1 in a Swedish population. Relationship to incidence of lung cancer.

Genetic polymorphism of CYP2E1 was investigated among 195 Swedish patients with lung cancer and 206 controls. Three different polymorphic sites were found, all in introns, using RFLP and the restriction enzymes DraI, RsaI and TaqI. The frequencies of the rare alleles were 0.08-0.18 and much lower than previously described among Japanese. No significant difference in distribution of the polymorphic alleles between controls and lung cancer patients was evident, in contrast to results of a previous Japanese study. However, examination of a polymorphic site in the 5'-flanking region, within a putative binding motif for the hepatic transcription factor HNF-1, revealed a significantly less frequent distribution of the mutated allele (c2) among the lung cancer patients as compared to controls. It is concluded that major interethnic differences exist in the genetic polymorphism of CYP2E1 and that people carrying the c2 allele might be at lower risk for developing lung cancer.

Base Sequence↗
PubMed1993

Polymorphic 2-hydroxylation of desipramine. A population and family study.

We have studied desipramine hydroxylation capacity, determined as the metabolic ratio of desipramine to 2-hydroxydesipramine in the urine after a single oral dose of 10 mg of desipramine, in 340 Swedish Caucasians, including the members of 45 two-generation families. Desipramine metabolic ratios were bimodally distributed among 237 unrelated subjects and 8% were poor metabolizers. There was a strong correlation between the metabolic ratios for desipramine and debrisoquine in 337 subjects phenotyped with both drugs and there was no dissociation between their capacities to hydroxylate desipramine and debrisoquine. Complex segregation analysis in the 45 families gave evidence for a major locus with incomplete recessivity (d = 0.14) controlling the 2-hydroxylation of desipramine. Similar results were obtained in segregation analysis for debrisoquine. There was evidence for linkage between the CYP2D6 gene and the gene regulating the hydroxylation of desipramine and debrisoquine. This study has provided unequivocal evidence that the capacity to 2-hydroxylate desipramine is polymorphic and under similar genetic control to the hydroxylation of debrisoquine.

Adolescent↗