Biomedical subjects

M Johansson

Publications and source records attributed to M Johansson.

At least 127 records · Page 7Linked to original sources

PubMed1999

Peripheral and intracerebral T cell immune response in cats naturally infected with Borna disease virus.

Borna disease virus (BDV) is a neurotropic agent with capacity to cause encephalomyelitis in a wide range of animal species, including horses and cats. Recent studies also point to a link between BDV and human neuropsychiatric disorders. The pathogenesis of Borna disease (BD) has been proposed to be immune-mediated, mainly through the effects of cytotoxic T cells. We used flow cytometric analysis in order to characterize the peripheral and intracerebral T cell immune response in cats naturally infected with BDV. Our results show the presence of two different CD8+ cell populations (CD8+low and CD8+high) in the blood, spleen and brain of these cats. In the brain, CD8+low cells predominated over CD8+high cells. Since CD8+low cells have been suggested to represent a non-MHC-restricted T cell population, the recruitment of such cells to the brains of BDV-infected cats could possibly be of importance for the clearance of virus from neurones.

Animals↗

PubMed1999

A prototype computer network service for occupational therapists.

Due to recent reforms, the demands on the people working in community-oriented health care service are increasing. The individual providers need professional knowledge and skills to perform their tasks quickly and safely. The individuals are also confronted with new tasks and situations of which they lack experience. At the same time, the resources for education and development are decreasing. The aim of this paper is to describe the implementation of a prototype computer network service to support occupational therapists in their daily work. A customized Quality Function Deployment (QFD) model, including participatory design elements, was used for: (a) identification of the occupational therapists' needs; and (b) for the transformation of these needs to prioritized design attributes. The main purpose of the prototype was to improve the visualization of the design attributes that were found to support the occupational therapists. An additional purpose was to be able to evaluate the design attributes and further improve them. The specific aim of this article is to describe the initial prototype with respect both to the tools and the information content.

Humans↗

PubMed1999

Migration and atopic disorder in Swedish conscripts.

We have studied asthma and allergic rhinitis prevalence in Swedish conscripts born 1973-1977 according to the military service conscription register in relation to the socio-economic status and country of birth of the conscripts and their parents, and age when granted residency in Sweden. There was an increase in prevalence of asthma and allergic rhinitis over time in all groups irrespective of country of birth or ethnic origin. Conscripts who themselves were born in Africa, Asia, Latin America and the Mediterranean had a significantly lower risk for asthma and allergic rhinitis than Swedish-born conscripts. The risk of atopic disorder among the foreign-born conscripts increased with time of residency in Sweden. Conscripts with mothers from Latin America, Asia and Africa were identified as having the highest risk for atopic disorder among Swedish-born conscripts with high socio-economic status; the adjusted risk ratio (RR) for asthma was 2.6 (95% CI 1.7-4.0) and that for allergic rhinitis was 2.0 (1.5-2.6). The conscripts with mothers from the Mediterranean had the lowest risk for atopic disorders of the Swedish-born conscripts with low socio-economic status; the RR for asthma was 0.43 (0.34-0.56) and that for allergic rhinitis was 0.84 (0.76-0.93). This study demonstrates that factors related to migration and ethnicity are important determinants of atopic disorder among Swedish conscripts.

Adolescent↗

PubMed1999

Effects of radiotherapy and estramustine on the microvasculature in malignant glioma.

Tumour angiogenesis is essential for progression of solid tumours and constitutes an interesting target for therapy. However, impaired tumour blood supply may also be an important obstacle for treatment by radiotherapy and chemotherapy. Estramustine has been shown to increase tumour blood flow and potentiate the effect of radiotherapy in experimental glioma. This study investigated the effects of fractionated radiotherapy and estramustine on angiogenesis in malignant glioma. The intracerebral BT4C rat glioma model was used and the animals were given whole brain radiotherapy 4 Gy x 5 days alone or in combination with estramustine 20 mg kg(-1) i.p. daily. Tumour microvascular density (MVD) was assessed by manual and computerized morphometrical analysis. Expression of vascular endothelial growth factor (VEGF) was studied by in situ hybridization. Radiotherapy decreased MVD to 157 vessels per mm2 compared to 217 vessels per mm2 in controls. Estramustine counteracted this anti-angiogenic effect and potentiated the anti-tumoural effect of radiotherapy. In addition, vessel size increased after estramustine treatment. Five days after completion of radiotherapy the expression of VEGF was increased in the centre of the tumours. In conclusion, fractionated radiotherapy decreases microvascular density in experimental malignant glioma. This effect was abolished by estramustine. The anti-vascular effect of irradiation is important to recognize when combining radiotherapy with cytotoxic drugs.

Animals↗

PubMed1999

A mechanism-based pharmacokinetic-enzyme model for cyclophosphamide autoinduction in breast cancer patients.

AIMS: This study investigated the pharmacokinetics of cyclophosphamide (CP) and its main metabolite 4-hydroxycyclophosphamide (4-OH-CP) in patients with breast cancer undergoing high dose chemotherapy prior to autologous stem cell transplantation. An enzyme turn-over model was also developed to study the time course of cyclophosphamide induction. METHODS: Fourteen patients received a combination of CP (6 g m-2 ), thiotepum (500 mg m-2 ) and carboplatin (800 mg m-2 ) as a 96 h infusion. Plasma concentrations of CP and 4-OH-CP were determined with h.p.l.c. and a pharmacokinetic and enzyme turn-over model applied to data using NONMEM. RESULTS: CP plasma concentrations were described by a two-compartment model with a noninducible and an inducible pathway, the latter forming 4-OH-CP. In the final enzyme model, CP affects the amount of enzymes by increasing the enzyme production rate. CP concentrations decreased during the infusion with no subsequent change in 4-OH-CP concentrations. CP inducible and noninducible clearance were estimated to 1.76 l h-1 (90% C.I. 0.92-2.58) and 1.14 l h-1 (0.31-1.85), respectively. The induction resulted in an approximately doubled CP clearance through the inducible pathway at the end of treatment. The model predicted the enzyme turn-over half-life to be 24 h. CONCLUSIONS: The presented mechanism-based enzyme induction model where the pharmacokinetics of the inducer and the enzyme pool counterbalance each other successfully described CP autoinduction. It is reasonable to believe that CP affects its own elimination by increasing the enzyme production rate and thereby increasing the amount of enzyme by which CP is eliminated.

Adult↗

PubMed1999

Identification of a novel human adenylate kinase. cDNA cloning, expression analysis, chromosome localization and characterization of the recombinant protein.

Adenylate kinases have an important role in the synthesis of adenine nucleotides that are required for cellular metabolism. We report the cDNA cloning of a novel 22-kDa human enzyme that is sequence related to the human adenylate kinases and to UMP/CMP kinase of several species. The enzyme was expressed in Escherichia coli and shown to catalyse phosphorylation of AMP and dAMP with ATP as phosphate donor. When GTP was used as phosphate donor, the enzyme phosphorylated AMP, CMP, and to a small extent dCMP. Expression as a fusion protein with the green fluorescent protein showed that the enzyme is located in the cytosol. Northern blot analysis with mRNA from eight different human tissues demonstrated that the enzyme was expressed exclusively in brain, with two mRNA isoforms of 2.4 and 4.0 kb. The gene that encoded the enzyme was localized to chromosome 1p31. Based on the substrate specificity and the sequence similarity with the previously identified human adenylate kinases, we have named this novel enzyme adenylate kinase 5.

Adenylate Kinase↗

PubMed1999

Human high-Km 5'-nucleotidase effects of overexpression of the cloned cDNA in cultured human cells.

5'-Nucleotidases participate, together with nucleoside kinases, in substrate cycles involved in the regulation of deoxyribonucleotide metabolism. Three major classes of nucleotidases are known, one on the plasma membrane and two in the cytosol. The two cytosolic classes have been named high-Km nucleotidases and 5'(3')-nucleotidases. Starting from two plasmids with partial sequences (Oka, J., Matsumoto, A., Hosokawa, Y. & Inoue, S. (1994) Biochem. Biophys. Res. Commun. 205, 917-922) we cloned the complete cDNA of the human high-Km nucleotidase into vectors suitable for transfection of Escherichia coli or mammalian cells. After transfection, E. coli overproduced large amounts of the enzyme. Most of the enzyme was present in inclusion bodies that also contained many partially degraded products of the protein. Part of the enzyme, corresponding to approximately 2% of the soluble proteins, was in a soluble active form. Stably transfected human 293 cells were obtained with a vector where the 3'-end of the nucleotidase coding sequence is linked to the 5'-end of the green fluorescent protein coding sequence. Several green clones overproduced both mRNA and fusion protein. Two clones with 10-fold higher enzyme activity were analyzed further. The nucleotidase activity of cell extracts showed the same substrate specificity and allosteric regulation as the high-Km enzyme. The growth rate of the two clones did not differ from the controls. The cells were not resistant to deoxyguanosine or deoxyadenosine, and did not show an increased ability to phosphorylate dideoxyinosine. Both ribonucleoside and deoxyribonucleoside triphosphate pools were decreased slightly, suggesting participation of the enzyme in their regulation.

5'-Nucleotidase↗

PubMed1999

Trends in overweight and obesity among 18-year-old males in Sweden between 1971 and 1995.

The aims of the study are to analyse Swedish trends in overweight and obesity-as measured by body mass index (BMI)-between 1971 and 1995, and to examine socioeconomic and geographic differences between groups of individuals on the basis of information on 18-y-old military conscripts. The study population comprises all males born in 1953, 1958, 1963, 1968, and between 1973 and 1977, reported to be living in Sweden at 17 y of age according to nationwide population registers (RTPs). Utilizing the unique personal ID number, sociodemographic data in the RTPs and in Population and Housing censuses were linked to data on BMI in the national Military Service Conscription Registry for the years 1971 to 1995. These data were obtained from compulsory medical examinations held at military induction at 18 y of age. BMI data were available for 448 732 (89%) of a total of 503 689 subjects. Mean BMI increased by 6.6% over the study period-from 21.1 kg/m2 in 1971 to 22.4 kg/m2 in 1995. Unadjusted trend analyses showed a 2.4 times increase in the prevalence of overweight among 18-y-old males over the period-from 6.9% in 1971 to 16.3% in 1995. Over the same years, the prevalence of obesity increased 3.5 times-from 0.9% to 3.2%. After adjustment for muscle power, demographic factors, and living area, the prevalence of overweight was found to have increased 1.4 times, and obesity 1.7 times between 1971 and 1993. The prevalence of overweight was considerably higher among 18-y-old males from low-educated families than among those from high-educated families in both 1971 and 1995. The prevalence of overweight was also found to be higher in both 1971 and 1995 among young men from rural and/or sparsely populated areas than among those living in Sweden's largest cities. Mean BMI, and the prevalence of overweight and obesity have increased among 18-y-old males in Sweden over the last 24 y. The increased risk of overweight among young men from low-educated families and those from rural and/or sparsely populated areas detected in 1971 was still evident in 1995.

Adolescent↗

PubMed1999

Mutations and impaired function of LKB1 in familial and non-familial Peutz-Jeghers syndrome and a sporadic testicular cancer.

Germline mutations in LKB1 have been reported to underlie familial Peutz-Jeghers syndrome (PJS) with intestinal hamartomatous polyps and an elevated risk of various neoplasms. To investigate the prevalence of LKB1 germline mutations in PJS more generally, we studied samples from 33 unrelated PJS patients including eight non-familial sporadic patients, 20 familial patients and five patients with unknown family history. Nineteen germline mutations were identified, 12 (60%) in familial and four (50%) in sporadic cases. LKB1 mutations were not detected in 14 (42%) patients, indicating that the existence of additional minor PJS loci cannot be excluded. LKB1 is predicted to encode a serine/threonine kinase. To demonstrate the putative Lkb1 kinase function and to study the consequences of LKB1 mutations in PJS and sporadic tumors, we have analyzed the kinase activity of wild-type and mutant Lkb1 proteins. Interestingly, while most of the small deletions or missense mutations resulted in loss-of-function alleles, one missense mutation (G163D) previously identified in a sporadic testicular tumor demonstrated severely impaired but detectable kinase activity.

AMP-Activated Protein Kinase Kinases↗

PubMed1999

Increased cardiovascular mortality in hypertensive patients with renal artery stenosis. Relation to sympathetic activation, renal function and treatment regimens.

BACKGROUND: Previous studies in hypertensive patients with renovascular disease have shown both elevated sympathetic nerve activity and increased cardiovascular mortality. OBJECTIVE: The aim of the present study was to assess long-term survival in hypertensive patients with renal artery stenosis in relation to sympathetic activation, renal function and treatment regimens. SUBJECTS AND METHODS: A total of 169 consecutive patients aged 54 +/- 1 years with hypertension underwent a clinical investigation for renovascular hypertension including renal angiography and measurement of bilateral renal renin secretion. In 107 of these patients, arterial plasma concentrations of noradrenaline were measured. The mean follow-up time was 7.1 +/- 0.3 years and survival data were available in all patients up to May 1997. For comparison, healthy age-matched normotensive controls were examined. RESULTS: Arterial noradrenaline concentrations were threefold elevated in hypertensive patients with renal artery stenosis compared to healthy controls (P < 0.01). During the follow-up time, 44 patients died. Cardiovascular mortality accounted for 75% of all deaths. The risk ratio for overall mortality in hypertensive patients with renal artery stenosis compared to the normal population of Sweden, matched for age, was 3.3 (2.4-4.4), whereas the risk ratio for cardiovascular mortality was 5.7 (3.9-8.0). The arterial plasma concentration of noradrenaline was 3.11 +/- 0.30 pmol/ml in patients who died compared to 3.84 +/- 0.26 pmol/ml in survivors. Reduced renal function and age were independent predictors of death. Survival did not differ between patients undergoing intervention with either renal angioplasty or surgical reconstruction for renal artery stenosis and patients not undergoing intervention. CONCLUSIONS: Although sympathetic nerve activity is elevated in hypertensive patients with renal artery stenosis, our results do not suggest that this adrenergic over-activity is directly linked to the observed high cardiovascular mortality. Mortality in hypertensive patients with renovascular disease remains high whether an interventional treatment is performed or not, possibly due to the concomitant coronary disease.

Angiography↗

PubMed1999

Phosphorylation of deoxycytidine analog monophosphates by UMP-CMP kinase: molecular characterization of the human enzyme.

Phosphorylation of deoxycytidine analogs by cellular enzymes is a prerequisite for the activity of these compounds. We have investigated the kinetic parameters for the phosphorylation of 1-beta-D-arabinofuranosylcytosine (araC) and 2', 2'-difluorodeoxycytidine (dFdC) to their diphosphate forms catalyzed by human UMP-CMP kinase. We cloned the cDNA of this enzyme to enable characterization of the recombinant protein, determine its expression in different tissues, and determine the chromosome location of the gene. We showed that the recombinant UMP-CMP kinase phosphorylated CMP, dCMP, and UMP with highest efficiency and dUMP, AMP, and dAMP with lower efficiency. The monophosphates of araC and dFdC were shown to be phosphorylated with similar efficiency as dCMP and CMP. We further showed, in a combined enzymatic assay, that human deoxycytidine kinase and UMP-CMP kinase together phosphorylated araC, dFdC, and 2',3'-dideoxycytidine to their diphosphate forms. Northern blot analysis showed that the UMP-CMP kinase mRNA was ubiquitously present in human tissues as a 3.9-kb transcript with highest levels in pancreas, skeletal muscle, and liver. The human UMP-CMP kinase gene was localized to chromosome 1p34.1-1p33 by radiation hybrid analysis. We further expressed the UMP-CMP kinase as a fusion protein to the green fluorescent protein in Chinese hamster ovary cells, and showed that the fusion protein was located in the cytosol and nucleus.

Amino Acid Sequence↗

PubMed1999

Purification of P(II) and P(II)-UMP and in vitro studies of regulation of glutamine synthetase in Rhodospirillum rubrum.

The P(II) protein from Rhodospirillum rubrum was fused with a histidine tag, overexpressed in Escherichia coli, and purified by Ni(2+)-chelating chromatography. The uridylylated form of the P(II) protein could be generated in E. coli. The effects on the regulation of glutamine synthetase by P(II), P(II)-UMP, glutamine, and alpha-ketoglutarate were studied in extracts from R. rubrum grown under different conditions. P(II) and glutamine were shown to stimulate the ATP-dependent inactivation (adenylylation) of glutamine synthetase, which could be totally inhibited by alpha-ketoglutarate. Deadenylylation (activation) of glutamine synthetase required phosphate, but none of the effectors studied had any major effect, which is different from their role in the E. coli system. In addition, deadenylylation was found to be much slower than adenylylation under the conditions investigated.

Adenosine Monophosphate↗

PubMed1999

Expression of P(II) and glutamine synthetase is regulated by P(II), the ntrBC products, and processing of the glnBA mRNA in Rhodospirillum rubrum.

We have studied the transcription of the glnB and glnA genes in Rhodospirillum rubrum with firefly luciferase as a reporter enzyme. Under NH(4)(+) and N(2) conditions, glnBA was cotranscribed from a weak and a strong promoter. In nitrogen-fixing cultures, activity of the latter was highly enhanced by NtrC, but transcription from both promoters occurred under both conditions. There is no promoter controlling transcription of glnA alone, supporting our proposal that the glnA mRNA is produced by processing.

Bacterial Proteins↗

PubMed1998

Positively and negatively charged residues have different effects on the position in the membrane of a model transmembrane helix.

We have studied the effects of single charged residues on the position of a model transmembrane helix in the endoplasmic reticulum membrane using the glycosylation mapping technique. Asp and Glu residues cause a re-positioning of the C-terminal end of the transmembrane helix when placed in the one to two C-terminal turns but not when placed more centrally. Arg and Lys residues, in contrast, have little effect when placed in the two C-terminal turn but give rise to a more substantial shift in position when placed 9-11 residues from the helix end. We suggest that this difference between the effects of positively and negatively charged residues can be explained by the so-called snorkel effect, i.e. that the very long side-chains of Arg and Lys can reach up along the transmembrane helix to allow the terminal, charged moiety to reside in the lipid headgroup region while the Calpha of the residue is positioned well below the membrane/water interface.

Amino Acid Sequence↗

PubMed1998

Phosphorylation of anticancer nucleoside analogs by human mitochondrial deoxyguanosine kinase.

The kinetic properties of recombinant human mitochondrial deoxyguanosine kinase (dGK, EC 2.7.1.113) for 2'-deoxyguanosine and the clinically important nucleoside analogs 2-chloro-2'-deoxyadenosine (CdA), 9-beta-D-arabinofuranosylguanine (araG) and 2',2',-difluorodeoxyguanosine (dFdG) were determined. The Michaelis-Menten kinetic parameters, comparing ATP and UTP as phosphate donors, demonstrated a marked increase in phosphorylation efficiency (VmaxKm) with UTP in comparison with ATP for both CdA and araG. The difluoro analog dFdG was an efficient substrate for recombinant dGK with an apparent Km of 16 microM with ATP as phosphate donor. We compared the kinetic properties of dGK with those of the related enzyme deoxycytidine kinase (dCK, EC 2.7.1.74). Although the purines 2'-deoxyguanosine (dGuo) and 2'-deoxyadenosine are substrates for both dGK and dCK, only CdA among the purine nucleoside analogs tested was an efficient substrate for both dCK and dGK. In competition with dGuo, the most efficient analog for phosphorylation by dGK was araG, as indicated by a lower Ki value than for CdA and dFdG. Of the purine analogs tested as substrates for dCK, only CdA could compete with 2'-deoxycytidine (dCyd). No inhibition of dCK-mediated dCyd phosphorylation was found by either araG or dFdG. In crude cell extract of HeLa and Capan 2 cells, the major CdA phosphorylation was contributed by dCK, while most araG phosphorylation was a result of dGK activity. Our study with pure recombinant enzymes confirms that dGK is mainly responsible for araG and dFdG phosphorylation, whereas dCK is the most important enzyme for activation of CdA and 2',2'-difluorodeoxycytidine (dFdC).

Antineoplastic Agents↗

PubMed1998

Enhanced cytotoxicity of nucleoside analogs by overexpression of mitochondrial deoxyguanosine kinase in cancer cell lines.

The cytotoxic anti-cancer purine nucleoside analogs 2-chloro-2'-deoxyadenosine (CdA), 9-beta-D-arabinofuranosylguanine (araG), and 2',2'-difluorodeoxyguanosine (dFdG) are phosphorylated by human mitochondrial deoxyguanosine kinase (dGK) in vitro. We overexpressed dGK as a fusion protein to the green fluorescent protein in the human pancreatic cancer cell lines PanC-1 and MIA PaCa-2 to determine the importance of dGK-mediated nucleoside analog phosphorylation. The transfected cells showed mitochondrial fluorescence patterns, and the mitochondrial locations of endogenous and overexpressed dGK were verified by Western blot analysis of cell extracts with polyclonal anti-dGK antibodies. The increase of dGK activity in the overexpressing cells was approximately 4-fold. These cell lines exhibited increased sensitivity to CdA, araG, and dFdG as compared with the untransfected parent cell lines. This is, to our knowledge, the first demonstration of a correlation between the activity of a mitochondrial deoxyribonucleoside kinase and the cytotoxicity of nucleoside analogs. Our data imply that the dGK activity is rate-limiting for the efficacy of nucleoside analogs in the cell lines investigated.

Antineoplastic Agents↗

PubMed1998

Artemisinin pharmacokinetics in healthy adults after 250, 500 and 1000 mg single oral doses.

Eight healthy male, Vietnamese subjects were administered 1 x 250, 2 x 250, and 4 x 250 mg artemisinin capsules in a cross-over design with randomized sequence with a 7-day washout period between administrations. The inter-individual variability in artemisinin pharmacokinetics was large with parameter coefficient of variation (CV) typically between 50-70%. The parameter with the smallest variability was the elimination half-life (CV approximately equal to 30-40%). Analysis of variance indicated also a large intra-subject variability. (CV, or = 24%) for the dose-normalized area under the plasma concentration-time curve (AUC/dose). The pharmacokinetic results suggested artemisinin to be subject to high pre-systemic extraction. Artemisinin half-life could not predict the extent of in vivo exposure to the drug, there being no correlation between half-life and oral clearance. Artemisinin oral plasma clearance was about 400 L h-1 exhibiting a slight decrease with dose, although the effect was weak. Thus results from studies using different artemisinin doses may, within the studied dose range, be compared without the complication of disproportionate changes in drug exposure with varying dose levels. Half-lives appeared to increase with dose. An observed period effect in the analysis of variance was tentatively associated with time-dependency in artemisinin pharmacokinetics. There was a high correlation between artemisinin plasma concentrations determined at various time-points after drug administration and the AUCs after the 500 and 1000 mg doses, but less so after the 250 mg dose. This may show a tentative approach to assess the systemic exposure of the patients to artemisinin from the determination of artemisinin plasma concentrations in one or two plasma samples only. Artemisinin was well tolerated with no apparent dose or time dependent effects on blood pressure, heart rate or body temperature.

Administration, Oral↗

PubMed1998

Cloning, sequencing and overexpression of a Rhodothermus marinus gene encoding a thermostable cellulase of glycosyl hydrolase family 12.

A gene library from the thermophilic eubacterium Rhodothermus marinus, strain ITI 378, was constructed in pUC18 and transformed into Escherichia coli. Of 5400 transformants, 3 were active on carboxymethylcellulose. Three plasmids conferring cellulase activity were purified and were all found to contain the same cellulase gene, celA. The open reading frame for the celA gene is 780 base pairs and encodes a protein of 260 amino acids with a calculated molecular mass of 28.8 kDa. The amino acid sequence shows homology with cellulases in glycosyl hydrolase family 12. The celA gene was overexpressed in E. coli when the pET23, T7 phage RNA polymerase system was used. The enzyme showed activity on carboxymethylcellulose and lichenan, but not on birch xylan or laminarin. The expressed enzyme had six terminal histidine residues and was purified by using a nickel nitrilotriacetate column. The enzyme had a pH optimum of 6-7 and its highest measured initial activity at 100 degrees C. The heat stability of the enzyme was increased by removal of the histidine residues. It then retained 75% of its activity after 8 h at 90 degrees C.

Bacterial Proteins↗