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Biomedical subjects

B Persson

Publications and source records attributed to B Persson.

At least 199 records · Page 11Linked to original sources
PubMed1994

Blood pressure response to physical exercise in healthy adolescents and adolescents with insulin-dependent diabetes mellitus.

1. Reference values for systolic blood pressure during exercise are provided for 88 healthy adolescents (12-22 years of age) of both sexes. Data were related to oxygen uptake, heart rate, blood lactate concentration, rate of perceived exertion, age, sex, body size and physical fitness. 2. The same variables were measured in 55 adolescents of both sexes with insulin-dependent diabetes mellitus of about 12 years duration and were analysed with respect to the healthy control group, to degree of metabolic control and to late diabetic complications. 3. In healthy adolescents the pressure response was not related to sex or age. When compared with control subjects diabetic patients had a higher diastolic blood pressure at rest and a more marked blood pressure increase, 23 versus 19 mmHg W-1 kg-1 body weight, during exercise with no sex difference. The blood pressure rise was not related to metabolic control, glomerular hyperfiltration or physical fitness. 4. Prolonged exercise tests were no more informative regarding the blood pressure response to exercise than the stepwise increased load test. Analysing the blood pressure increase versus relative work load (W/kg body weight) during exercise reveals blood pressure differences otherwise not noted. A diabetic patient with blood pressure above the 97.5% confidence limit during exercise seems to have a higher risk of developing incipient nephropathy 5 years later.

Adolescent↗
PubMed1994

Hormonal, metabolic, and circulatory responses to insulin-induced hypoglycemia in pregnant and nonpregnant women with insulin-dependent diabetes.

Strict blood glucose control of pregnant women with insulin-dependent diabetes is associated with increased risk of hypoglycemia. The hormonal and circulatory responses to an acute episode of insulin-induced hypoglycemia were studied in eight pregestational and one gestational diabetic women during the last trimester of pregnancy and 8 to 12 weeks postpartum. Following an overnight fast, insulin was injected intravenously (0.1 to 0.2 IU insulin/kg). Blood samples were taken at -15, 0, 15, 30, 40, 60, 90, and 120 minutes for analyses of metabolites (glucose, nonesterified fatty acid (NEFA), glycerol, 3-hydroxybutyrate) and counterregulatory hormones (epinephrine, norepinephrine, glucagon, and cortisol). Placental scintigraphy (indium-113m) was performed in five pregnant patients before and during hypoglycemia. Both during pregnancy and postpartum, blood glucose decreased to the same low level (3.2 mmol/L) concomitantly with significant decreases in NEFA, glycerol, and 3-hydroxybutyrate. Epinephrine and norepinephrine showed significant and similar increases on both occasions in relation to hypoglycemia, although there was no response in glucagon and cortisol concentrations. Maternal heart rate was significantly higher in the pregnant compared with the nonpregnant state and increased significantly in both groups in response to hypoglycemia. Placental blood flow showed no consistent changes and was unrelated to the glucose and catecholamine responses. Fetal heart rate remained unchanged. Thus, it seems as if hormonal and circulatory responses to acute hypoglycemia are not altered in diabetic women during pregnancy.

3-Hydroxybutyric Acid↗
PubMed1994

The efficacy of multiple risk factor intervention in treated hypertensive men during long-term follow up. Risk Factor Intervention Study Group.

OBJECTIVE: To examine the feasibility and efficacy of a multifactorial intervention programme directed towards hypercholesterolaemia, smoking, and diabetes mellitus in treated hypertensive patients after more than 3 years' follow-up and to describe the incidence of cardiovascular complications. DESIGN: Open, randomized, parallel-group study with allocation either to a comprehensive multiple risk factor modification programme or to usual care. SETTING: Outpatient clinic in a city hospital. PATIENTS: A total of 508 male patients with treated hypertension, aged 50-72 years, with at least one of the following: serum cholesterol > or = 6.5 mmol L-1, smoking or diabetes mellitus. INTERVENTION: Individually given advice and group meetings based on nutritional advice and behavioral treatment principles. Drug therapy could be instituted to achieve the treatment goals in the intervention group: serum total cholesterol below 6.0 mmol L-1, no smoking, and HbA1c below 6.0%. Diastolic blood pressure below 90 mmHg was the treatment goal in both groups. MAIN OUTCOME MEASUREMENTS: Serum cholesterol, HbA1c, diastolic blood pressure, smoking. Cardiovascular end-points were recorded. RESULTS: The net changes were (change intervention--change usual care): serum cholesterol -5.0% (95% confidence interval, -7.6 to -2.3%), 17.6% more stopped smoking (P = 0.04); diastolic blood pressure and HbA1c remained unchanged. The incidence of stroke was lower in the intervention group compared with the usual-care group: 2.0 and 6.7%, respectively (P = 0.017). CONCLUSION: The intervention programme was comparatively successful with regards to the effects on hypercholesterolaemia and smoking habits. An unexpected decrease in the stroke incidence was observed in the intervention group compared with the usual-care group.

Aged↗
PubMed1994

The role of diabetes mellitus and hypertriglyceridaemia as coronary risk factors in treated hypertension: 15 years of follow-up of antihypertensive treatment in middle-aged men in the Primary Prevention Trial in Göteborg, Sweden.

OBJECTIVE: To analyse the importance of diabetes mellitus and hypertriglyceridaemia as potential risk factors for coronary heart disease (CHD) in middle-aged, treated hypertensive men. DESIGN: A prospective, long-term observational study. SUBJECTS: Derived from a random population sample--686 hypertensive men aged 47-54 years at entry--followed for 15 years at a special out-patient hypertension clinic. INTERVENTION AND OUTCOME MEASURES: The patients were mainly treated with beta-adrenoceptor blockers and/or thiazide diuretics. Cardiovascular morbidity was closely monitored during follow-up. RESULTS: In all, 133 subjects suffered a CHD event during follow-up. The presence of diabetes mellitus at entry more than doubled the CHD risk and a 1 mmol l-1 increment of the serum triglyceride level at entry increased the CHD risk by 21%. In multivariate analyses, smoking, the presence of diabetes mellitus at entry, serum cholesterol and signs or symptoms of hypertensive end organ damage were found to be independent risk factors for CHD. In absolute terms the existence of cardiovascular damage was of much greater prognostic importance than were the presence of various metabolic abnormalities. Of the mean in-study variables, both the average serum cholesterol level and the achieved diastolic blood pressure were significantly associated with CHD. However, new diabetes mellitus which developed during follow-up as well as mean serum triglyceride levels were not associated with CHD. CONCLUSIONS: Diabetes mellitus and hypertriglyceridaemia present at the start of treatment have a prognostic impact in treated hypertensive men, whereas when such metabolic disorders develop during drug treatment they seem to be of much less importance. Smoking and already existing evidence of hypertensive end organ damage are of utmost importance for the prognosis in this type of patient.

Adrenergic beta-Antagonists↗
PubMed1994

Demonstration of voltage-dependent and TTX-sensitive Na(+)-channels in human melanocytes.

The electrophysiological properties of cultured human melanocytes were investigated using the whole-cell configuration of the patch-clamp technique. Depolarizations to membrane potentials more positive than -30 mV resulted in the rapid development ( < 1 ms to peak) of an inward current. The maximum peak current was observed at +10 mV and reached an average amplitude of about 270 pA. During the depolarizations, the current inactivated with a time constant of about 2 ms. The current was abolished by the addition of 0.3 microM tetrodotoxin, a blocker of voltage-gated Na(+)-channels, and disappeared when Na+ was omitted from the extracellular medium. In addition, the melanocytes contain at least two types of outward K(+)-current. The first type, observed in every cell, was highly sensitive (Ki 1 mM) to the K(+)-channel blocker TEA, required depolarizations beyond zero to be activated and did not inactivate. The second type was less regularly observed (10% of the cells). This current activated at more negative voltages (-20 mV), was resistant to TEA (20 mM) but was blocked by 2 mM 4-aminopyridine and inactivated rapidly during depolarizations. We conclude that human melanocytes are equipped with voltage-dependent Na(+)-channels, a delayed rectifying K(+)-current and a K(+)-current similar to the A-current in neurones.

4-Aminopyridine↗
PubMed1994

Lactate in fetal scalp blood and umbilical artery blood measured during normal labor with a test strip method.

A new test strip method was used to determine the lactate concentration in fetal scalp blood during normal labor. Sixty-six fetal scalp blood samples were collected at cervical dilatations between 4 cm and 10 cm. The mean lactate value was 1.7 +/- 0.8 mmol/l simultaneously (IS.D.) and the mean pH sampled simultaneously was 7.36 +/- 0.04 (IS.D.). The corresponding values for base deficit was 2.1 (+/- 1.9) and for pCO2 5.8 (+/- 0.8). No difference was seen in lactate concentrations or pH values in early compared to late first stage of labor. The mean lactate concentration in the umbilical artery immediately after delivery was 3.7 mmol/l +/- 1.2 (IS.D.). The method was easy to handle and gave the result within 60 seconds.

Female↗
PubMed1994

Comparison of information sources for case-referent data.

OBJECTIVES: Exposure assessment and the ascertainment of cases are topics of main concern in epidemiologic research. To investigate validity aspects of this kind practically, a comparative evaluation was performed of information sources for case-referent data. METHODS: Cases of Hodgkin's disease and non-Hodgkin's lymphoma diagnosed in 1975-1984 were collected from the Regional Cancer Register in Linköping. The study population was restricted to men 20-80 years of age at diagnosis. Living cases included in a previous case-referent study and the complementary cases from the register were compared with regard to the exposures indicated by job title and industrial branch, as given in the National Population Census in 1975. Furthermore, questionnaire-based exposure information from the case-referent study was compared with exposures derived from census information. RESULTS: Only 21% of all of the cases in the study base had been included in the questionnaire-based case-referent study. No major differences in the distribution of exposure were found for the two case series, except that fewer subjects were economically inactive in the previous case-referent study. No clear relations appeared between survival and particular exposures. Risk estimates derived from the present cancer register study were compared with corresponding estimates from the previous case-referent study. With restriction to only economically active cases, the risk estimates approached those of the case-referent study. CONCLUSIONS: This comparison showed that incomplete ascertainment of cases in a case-referent study was not an important source of bias, at least not in relation to what could be achieved by more complete case ascertainment through register linkage.

Adult↗
PubMed1994

Diabetes mellitus in treated hypertension: incidence, predictive factors and the impact of non-selective beta-blockers and thiazide diuretics during 15 years treatment of middle-aged hypertensive men in the Primary Prevention Trial Göteborg, Sweden.

The objective of this study was to analyse predictive factors for the development of diabetes mellitus during long-term treatment of hypertension and to compare the diabetogenic potential of thiazide diuretics and non-selective beta-adrenoceptor blockers. The study population comprised 686 hypertensive men, aged 47-54 years, who were followed for 15 years. Patients were treated with either thiazide diuretics or beta-adrenoceptor blockers as monotherapy or in combination with one another or alternative other antihypertensive drugs. During the first part of the study, i.e. during the 1970s, only non-selective beta-adrenoceptor blockers were used. The average yearly incidence of the development of diabetes mellitus during follow-up was 1.3%. In univariate analysis body mass index, serum triglyceride level, radiographic heart enlargement and beta-blocker therapy were significantly associated with the development of diabetes mellitus. Predictors selected by stepwise Cox regression were body mass index, radiological heart enlargement and beta-blocker therapy. Two subgroups with patients treated with nonselective beta-adrenoceptor blockers but not with thiazide diuretics during the first five years of follow-up (the beta-blocker group; n = 93) or with thiazide diuretics but not with nonselective beta-adrenoceptor blockers during the first five years of follow-up (the thiazide-group; n = 96) were identified. The relative risk for developing diabetes mellitus was significantly higher in the beta-blocker group being 6.1 after 10 years and 3.5 after 15 years treatment in comparison with the thiazide group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗
PubMed1993

Variability patterns of dehydrogenases versus peptide hormones and proteases/antiproteases.

Comparisons of human/rat species variants of 23 dehydrogenases versus 41 entries for peptide hormones and 41 for proteases/antiproteases reveal characteristic patterns. Dehydrogenases are 'constant' (2-8% residue differences between homologues) or 'variable' (12-40% differences). Peptide hormones exhibit a wider range, with many 'strictly conserved' and others spreading upscale, while proteases/antiproteases are overall shifted upscale, with few 'constant' and many 'variable'. Overall, the influence of polypeptide size and function is confirmed, while for the dehydrogenases, the data highlight the 'constant' pattern as the one with high frequency values and suggest for classic liver alcohol dehydrogenase the 'variable' pattern to correlate with emerging functions.

Amino Acid Sequence↗
PubMed1993

Analysis of active antibody concentration. Separation of affinity and concentration parameters.

Antibody binding to surfaces with differing amounts of immobilised antigen was measured in a biosensor system using surface plasmon resonance detection. Binding rates obtained during the initial binding phase on high density antigen surfaces were proportional to antibody concentration and independent of antigen-antibody affinity. One antibody calibration curve covering the range from 0.5 to 160 nM (0.08-25 micrograms/ml) antibody was valid for IgG antibodies with different antigen specificities. To illustrate the use of this methodology active antibody concentrations were analysed in culture media and in rabbit serum.

Animals↗
PubMed1993

Some occupational exposures as risk factors for malignant lymphomas.

BACKGROUND: Malignant lymphomas (Hodgkin disease [HD] and non-Hodgkin lymphoma [NHL]) have been subject to several epidemiologic studies and found to be associated with various environmental exposures, especially solvents, wood, and phenoxy herbicides. METHODS: Various determinants for HD and NHL were evaluated in a case-referent study encompassing 31 cases of HD, 93 cases of NHL, and 204 referents, all alive. Information on these determinants, mainly occupational exposures, was obtained by mailed questionnaires. RESULTS: Crude odds ratios were increased for various occupational exposures, i.e., exposures to solvents, pesticides, metal fumes, welding, and fresh wood, and nursing. Further analyses based on logistic regression indicated exposure to phenoxy herbicides and fresh wood among sawmill workers, lumberjacks, and paper pulp workers to be significant risk factors for HD. Welding, working as a lumberjack, nursing, and ex-smoking were associated with a significantly increased risk for NHL. Radiographic examinations were negatively associated with HD, as was office work for NHL. CONCLUSIONS: The results were mainly in agreement with the findings of earlier studies, but diverging associations also appeared.

Adult↗
PubMed1993

Mapping of the antibody- and receptor-binding domains of granulocyte colony-stimulating factor using an optical biosensor. Comparison with enzyme-linked immunosorbent assay competition studies.

An automated optical biosensor instrument for measuring molecular interactions (Pharmacia BIAcore) has been used to characterise the epitopes recognised by 15 monoclonal antibodies raised against recombinant human granulocyte colony-stimulating factor (G-CSF). The BIAcore combines an autosampler and integrated microfluidic cartridge for the introduction and transportation of samples to the sensor chip surface, with surface plasmon resonance to detect binding events. A rabbit anti-mouse Fc antibody, coupled to the sensor surface in situ using conventional protein chemistry techniques, was used to capture an anti-G-CSF monoclonal antibody. G-CSF was bound to this antibody by injection over the sensor surface. Multi-site binding experiments were then performed in which other anti-G-CSF monoclonal antibodies were injected sequentially over the surface, and their ability to bind to the G-CSF in a multimolecular complex monitored in real time. Results obtained using the biosensor have been compared with data obtained by cross competition studies using biotinylated antibodies or antibody binding studies using chemically or enzymatically derived G-CSF peptide fragments or synthetic peptides. The results of these studies are in excellent agreement with the data from the BIAcore, although modification of the antibody or G-CSF occasionally altered the epitope affinity.

Animals↗
PubMed1993

Basic features of class-I alcohol dehydrogenase: variable and constant segments coordinated by inter-class and intra-class variability. Conclusions from characterization of the alligator enzyme.

The enzymatic and structural properties of alligator liver alcohol dehydrogenase have been determined. Aliphatic and alicyclic alcohols serve as substrates for this first reptilian form of the enzyme characterized, with Km values decreasing rapidly from methanol to hexanol, as for the human class I enzymes, and a Km of 1.2 mM for ethanol at pH 9.9. The N-terminus of the 374-residue protein chain is acetyl-blocked. The enzyme is related in descending order to class I > III > V > II of the structurally characterized mammalian alcohol dehydrogenases. This observation is compatible with the presence of a I/III ancestral line. Differences of the enzyme classes exceed those of the species, suggesting an early origin of the classes. Within its enzyme class, the reptilian protein is most closely related to the avian form (82% residue identities), and is closer to the human than to the amphibian form (76%, versus 69%, respectively). This establishes class I alcohol dehydrogenase as an enzyme having fairly constant rate of change during much of vertebrate evolution, approximately 10% residue differences/100 million years of separation between pairs compared. Residues interacting with the substrate and coenzyme are largely conserved. In the alligator enzyme, there are only four replacements in the substrate pocket compared with the human class I gamma subunit, and those are not known to have functional roles. These properties account for the kinetic parameters, and suggest distinct metabolic functions for the class I enzyme in vertebrates. Comparisons of the enzymes of the different vertebrate lines reveal that segment patterns are characteristic features of the class I enzymes. Three segments are 'variable', while two are 'constant', and both these types of segment are identical with those of the classes. There is extensive variability in close proximity to the active site of the enzyme and this appears to constitute a fundamental property of class I liver alcohol dehydrogenases in general.

Alcohol Dehydrogenase↗
PubMed1993

Dual relationships of xylitol and alcohol dehydrogenases in families of two protein types.

Xylitol dehydrogenase encoded by gene XYL2 from Pichia stipitis is a member of the medium-chain alcohol dehydrogenase family, as evidenced by the domain organization and a distant homology (24% residue identity with the human class I gamma 1 alcohol dehydrogenase). Much of a loop structure is missing, like in mammalian sorbitol and prokaryotic threonine dehydrogenases, many additional differences occur, and relationships are closest with the sorbitol dehydrogenase, the equivalence of which in P. stipitis may actually be the xylitol dehydrogenase. A second P. stipitis gene, also cloned and corresponding to a xylitol dehydrogenase, is highly different from XYL2, but encodes an enzyme with structural properties typical of the short-chain dehydrogenase family, which also contains an alcohol dehydrogenase (from Drosophila). Thus, yeast xylitol dehydrogenases, like alcohol and polyol dehydrogenases from other sources, have dual derivations, combining similar enzyme activities in separate protein families. In contrast to the situation with the other enzymes, both forms of xylitol dehydrogenase are present in one organism.

Alcohol Dehydrogenase↗
PubMed1993

Zeta-crystallin versus other members of the alcohol dehydrogenase super-family. Variability as a functional characteristic.

Species variability of the lens protein zeta-crystallin was correlated with those of alcohol dehydrogenases of classes I and III and sorbitol dehydrogenase in the same protein family. The extent of overall variability, nature of residues conserved, and patterns of segment variability, all fall within the limits typical of the 'variable' group of medium-chain alcohol dehydrogenases. This shows that zeta-crystallin is subject to restrictions similar to those of classical liver alcohol dehydrogenase and therefore derived from a metabolically active enzyme like other enzyme crystallins. Special residues at the active site, however, differ substantially, including an apparent lack of a zinc-binding site. This is compatible with altered functional properties and makes the spread within this medium-chain dehydrogenase family resemble the wide spread within the short-chain dehydrogenases. Schematic plotting is useful for illustrating the differences between 'variable' and 'constant' enzymes.

Alcohol Dehydrogenase↗
PubMed1993

Glucose-6-phosphate dehydrogenase. Structure-function relationships and the Pichia jadinii enzyme structure.

The primary structure of glucose-6-phosphate dehydrogenase from the yeast Pichia jadinii (formerly Candida utilis) has been determined. It consists of a 495-residue, N-terminally acetylated protein chain. The structure shows extensive differences from those of the corresponding mammalian, fruit fly, and bacterial enzymes (52-68% residue non-identities), but also from that of another yeast, Saccharomyces cerevisiae (38%). A eubacterial type and a yeast type of glucose-6-phosphate dehydrogenase are discerned, in addition to the known mammalian type. They are distinguished from each other, from the mammalian type, and the insect enzyme, on the basis of both specific residues and pattern differences. The distribution of residues conserved in all forms locates short segments in which identities are closely grouped. Approximately 50% of these segments correspond to predicted turns and appear to mark the principal folds characteristic of the enzyme's tertiary structure. A region in the N-terminal part of the protein chain has characteristics suggestive of a coenzyme-binding site, while, in the middle third, another functionally important segment may be related to glucose-6-phosphate binding and catalysis.

Amino Acid Sequence↗