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O Pedersen

Publications and source records attributed to O Pedersen.

At least 181 records · Page 10Linked to original sources
PubMed1994

Sequence of the human glycogen-associated regulatory subunit of type 1 protein phosphatase and analysis of its coding region and mRNA level in muscle from patients with NIDDM.

Impaired insulin-stimulated glycogen synthesis of peripheral tissues is a characteristic feature of many patients with non-insulin-dependent diabetes mellitus (NIDDM) and their first-degree relatives with normal glucose tolerance, suggesting putative inherited defects in this metabolic pathway. In previous studies, we have failed to reveal mutations in the coding regions of the muscle-specific glycogen synthase gene and the three genes that encode the catalytic subunits of protein phosphatase 1 (PP1) as frequent causes of insulin resistance. Because the glycogen-associated regulatory subunit of protein phosphatase 1 (PP1 G-subunit) plays a key role in the insulin stimulation of glycogen synthesis and the activity of PP1 is decreased in insulin-resistant subjects, we have now cloned the human G-subunit cDNA to search for abnormalities in the corresponding gene (designated PPP1R3 in the human genome nomenclature) in patients with NIDDM. The human cDNA was isolated from a skeletal muscle cDNA library and was found to encode a 126-kDa protein, which shows 73% amino acid identity to the rabbit PP1 G-subunit. The human G-subunit cDNA from 30 insulin-resistant NIDDM patients was analyzed for genetic variations in the G-subunit by using single-stranded conformation polymorphism (SSCP) scanning of reversely transcribed mRNA. One variant SSCP profile was detected in the region encoding the COOH-terminal part of the PP1 G-subunit in only one NIDDM patient, and subsequent nucleotide sequencing showed a C to A transversion on one allele at base position 2792. This change predicts an amino acid substitution from alanine to glutamic acid.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1994

Continuous reaction time after single dose, long-term oral and epidural opioid administration.

Auditory continuous reaction time was studied in three treatment groups. Twenty opioid naive patients received intramuscular morphine 0.15 mg kg-1 bodyweight for premedication. Thirty-one cancer patients were treated with oral opioids, 180 mg morphine per 24 h (median). Twenty-two cancer patients were treated with epidural morphine, 79 mg morphine per 24 h (median). The treatment groups were compared to a control group of 44 healthy persons taking no analgesics. The reaction time was measured using 152 auditory signals and summarized as 10%, 50% and 90% percentiles. Analysing reaction time distributions, the opioid naive patients showed the greatest difference to the control group in the shortest reaction times while chronic opioid users showed the greatest difference for the longest reaction times. There seems to be a qualitative difference in reaction time distribution, between opioid naive individuals treated with single dose morphine and cancer patients in long-term treatment.

Acoustic Stimulation↗
PubMed1993

Aminoacid polymorphisms of insulin receptor substrate-1 in non-insulin-dependent diabetes mellitus.

Since relative or absolute insulin deficiency and insulin insensitivity are involved in the aetiology of non-insulin-dependent diabetes mellitus (NIDDM), we examined whether patients with NIDDM exhibit genetic variability in the coding region of insulin receptor substrate-1 (IRS-1), a candidate gene that is ubiquitous in insulin-sensitive and insulin-like growth factor 1 (IGF1) sensitive tissues, including those that determine glucose production and clearance and those with regulatory effects on pancreatic beta-cell function. IRS-1 has a central role as an adaptor molecule that links the insulin-receptor and IGF1-receptor kinases with enzymes that regulate cellular metabolism and growth. Single-stranded conformation polymorphism analysis and direct nucleotide sequencing were applied to genomic DNA from 86 unrelated patients with NIDDM and 76 normoglycaemic controls. 10 of the patients with NIDDM and 3 of the controls were heterozygous at codon 972 for a polymorphism in which glycine was substituted with arginine. Moreover, at codon 513, 6 patients with NIDDM and 2 controls had a heterozygous polymorphism with a transition from alanine to proline. None of the polymorphism carriers had both aminoacid variants and the total allelic frequency of IRS-1 polymorphisms was about three times higher in patients with NIDDM than in controls (p = 0.02). Both aminoacid substitutions were located close to tyrosine phosphorylation motifs that are putative recognition sites for insulin and IGF1 signal transmission proteins. Analysis of the phenotypes showed that patients with NIDDM who had IRS-1 variants did not differ in their degree of insulin resistance compared with patients without known IRS-1 polymorphisms. However, carriers of the codon 972 variant had significantly lower plasma levels of fasting insulin and C-peptide. Our results suggest that aminoacid polymorphisms in IRS-1 may be involved in the aetiology of a subset of late-onset NIDDM.

Amino Acids↗
PubMed1993

Glut 4 content in the plasma membrane of rat skeletal muscle: comparative studies of the subcellular fractionation method and the exofacial photolabelling technique using ATB-BMPA.

UNLABELLED: Employing subcellular membrane fractionation methods it has been shown that insulin induces a 2-fold increase in Glut 4 protein content in the plasma membrane of skeletal muscle from rats. Data based upon this technique are, however, impeded by poor plasma membrane recovery and cross-contamination with intracellular membrane vesicles. The present study was undertaken to compare the subcellular fractionation technique with the technique using [3H]ATB-BMPA exofacial photolabelling and immunoprecipitation of Glut 4 on soleus muscles from 3-week-old Wistar rats. Maximal insulin stimulation resulted in a 6-fold increase in 3-O-methylglucose uptake, and studies based on the subcellular fractionation method showed a 2-fold increase in Glut 4 content in the plasma membrane, whereas the exofacial photolabelling demonstrated a 6- to 7-fold rise in cell surface associated Glut 4 protein. Glucose transport activity was positively correlated with cell surface Glut 4 content as estimated by exofacial labelling. IN CONCLUSION: (1) the increase in glucose uptake in muscle after insulin exposure is caused by an augmented concentration of Glut 4 protein on the cell surface membrane, (2) at maximal insulin stimulation (20 mU/ml) approximately 40% of the muscle cell content of Glut 4 is at the cell surface, and (3) the exofacial labelling technique is more sensitive than the subcellular fractionation technique in measuring the amount of glucose transporters on muscle cell surface.

3-O-Methylglucose↗
PubMed1993

Centrifuge-blotting of proteins after separation by sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

A protein transfer method which allows elution and immobilization of polypeptides onto a polyvinylidene difluoride (PVDF) membrane has been developed. The protein band in a gel is eluted by centrifugation. The centrifuge-blotting procedure involves the following steps: (i) visualization of the protein in a sodium dodecyl sulfate (SDS)-polyacrylamide gel with 1 M KCl, (ii) excision of the protein band and equilibration for 15 min in a solution of 0.05% SDS/5% methanol/0.02% dithiothreitol in distilled water, (iii) placing the gel piece in direct contact with the PVDF membrane in the receptacle, (iv) centrifugation at 3000 g for 1 h. A 10 kDa cut-off dialysis membrane is placed beneath the PVDF membrane to retain nonimmobilized protein. The N-terminal sequence of the immobilized protein on the PVDF membrane was determined. For proteins with a molecular mass less than 30 kDa, an overall yield between 10%-30% has been obtained.

Centrifugation↗
PubMed1993

The effect of intensive insulin therapy on the insulin-regulatable glucose transporter (GLUT4) expression in skeletal muscle in type 1 diabetes.

Studies in normal man and rodents have demonstrated that the expression of the dominant glucose transporter in skeletal muscle, GLUT4, is regulated by insulin at supraphysiological circulating levels. The present study was designed to determine whether intensified insulin replacement therapy for 24 h given to patients with Type 1 diabetes in poor metabolic control was associated with an adaptive regulation of GLUT4 mRNA and protein levels in vastus lateralis muscle. Nine Type 1 diabetic patients with a mean HbA1c of 10.3% were included in the protocol. After intensified treatment with soluble insulin for 24 h the fasting plasma glucose concentration decreased from 20.8 +/- 2.3 (SD) to 8.7 +/- 2.3 mmol 1-1, whereas the fasting serum insulin level increased from 0.06 +/- 0.02 to 0.17 +/- 0.09 nmol 1-1. However, despite a 2.8-fold increase in serum insulin levels and more than a halving of the plasma glucose concentration for at least 15 h no significant alterations occurred in the amount of GLUT4 protein (0.138 +/- 0.056, poor control vs 0.113 +/- 0.026 arb. units, improved control, p = 0.16) or GLUT4 mRNA (96432 +/- 44985, poor control vs 81395 +/- 25461 arb. units, improved control, p = 0.54). These results suggest, that in spite of evidence that high insulin levels affect GLUT4 expression in muscle, changes in serum insulin within the physiological range do not play a major role in the short-term regulation of GLUT4 expression in Type 1 diabetic patients.

Adult↗
PubMed1993

Increased insulin-stimulated glucose uptake in athletes: the importance of GLUT4 mRNA, GLUT4 protein and fibre type composition of skeletal muscle.

In the present study the expression of GLUT4 and fibre type composition were examined in biopsies from skeletal muscle in seven male athletes and eight male sedentary subjects. Estimated maximal oxygen uptake was increased in the trained group when compared with the sedentary group (74.0 +/- 3.9 vs. 42.9 +/- 5.1 ml kg-1 min-1; P < 0.01). A biopsy of vastus lateralis muscle was taken in the fasting state, 36 h after the last bout of exercise. A second muscle biopsy was obtained following 4 h of a hyperinsulinaemic (2 mU kg-1 min-1), euglycaemic clamp. The rate of insulin-stimulated glucose uptake was increased in the trained subjects (17.34 +/- 0.53 vs. 13.53 +/- 0.79 mg kg-1 min-1, P < 0.01). In parallel, the steady state levels of GLUT4 protein and mRNA per DNA were higher in muscle biopsies obtained in the basal state from athletes than in sedentary controls, 21 and 71% respectively (P < 0.05). In the total group of participants, GLUT4 protein per DNA in the basal state and insulin-stimulated glucose uptake rate correlated positively, (r = 0.51, P = 0.05). In the insulin-stimulated state we did not find any significant correlation between GLUT4 protein per DNA and glucose uptake rate (r = 0.13, n.s.). No significant relationships between GLUT4 protein abundance per DNA and muscle fibre type distribution were observed. A significantly negative correlation was found between type 2B fibre area and insulin-stimulated glucose uptake (r = -0.63, P < 0.05). In conclusion, the abundance of GLUT4 protein and mRNA, respectively, is increased in skeletal muscle from endurance trained subjects compared to sedentary subjects. However, factors other than GLUT4 immunoreactive protein abundance seem to be determinant for the increased insulin-stimulated whole body glucose uptake in endurance trained subjects.

Adult↗
PubMed1993

Effect of physical training on glucose transporter protein and mRNA levels in rat adipocytes.

Physical training increases insulin-stimulated glucose transport and the number of glucose transporters in adipocytes measured by cytochalasin B binding. In the present study we used immunoblotting to measure the abundance of two glucose transporters (GLUT-4, GLUT-1) in white adipocytes from trained rats. Furthermore, the abundance of the mRNAs for these proteins and glucose transport was measured. Rats were swim-trained for 10 wk, and adipocytes were isolated from epididymal fat pads. The amount of GLUT-4/adipocyte volume unit was significantly higher in trained animals compared with both age- and cell size-matched animals. The amount of GLUT-4 mRNA was also increased by training and it decreased with increasing age. Furthermore, young age as well as training was accompanied by relatively low GLUT-4 protein/mRNA and relatively high overall GLUT-4 efficiency (recruitability and/or intrinsic activity). GLUT-1 protein and mRNA levels/adipocyte volume did not change with age or training.

3-O-Methylglucose↗
PubMed1993

GLUT-4 content in plasma membrane of muscle from patients with non-insulin-dependent diabetes mellitus.

The abundance of GLUT-4 protein in both total crude membrane and plasma membrane fractions of vastus lateralis muscle from 13 obese non-insulin-dependent diabetes mellitus (NIDDM) patients and 14 healthy subjects were examined in the fasting state and after supraphysiological hyperinsulinemia. In the basal state the immunoreactive mass of GLUT-4 protein both in the crude membrane preparation and in the plasma membrane fraction was similar in NIDDM patients and control subjects. Moreover, in vivo insulin exposure neither for 30 min nor for 4 h had any impact on the content of GLUT-4 protein in plasma membranes. With the use of the same methodology, antibody, and achieving the same degree of plasma membrane purification and recovery, we found, however, that intraperitoneal administration of insulin to 7-wk-old rats within 30 min increased the content of GLUT-4 protein more than twofold (P < 0.01) in the plasma membrane from red gastrocnemius and soleus muscle. In conclusion, when the subcellular fractionation method was applied to human muscle biopsies taken in the basal state, no difference could be found in the plasma membrane content of immunoreactive GLUT-4 protein between NIDDM patients and normal subjects. With this technique, we were unable to show evidence for a regulatory effect of insulin on the plasma membrane level of GLUT-4 protein in human muscle.

4-Nitrophenylphosphatase↗
PubMed1993

Glycogen synthase and phosphofructokinase protein and mRNA levels in skeletal muscle from insulin-resistant patients with non-insulin-dependent diabetes mellitus.

In patients with non-insulin-dependent diabetes mellitus (NIDDM) and matched control subjects we examined the interrelationships between in vivo nonoxidative glucose metabolism and glucose oxidation and the muscle activities, as well as the immunoreactive protein and mRNA levels of the rate-limiting enzymes in glycogen synthesis and glycolysis, glycogen synthase (GS) and phosphofructokinase (PFK), respectively. Analysis of biopsies of quadriceps muscle from 19 NIDDM patients and 19 control subjects showed in the basal state a 30% decrease (P < 0.005) in total GS activity and a 38% decrease (P < 0.001) in GS mRNA/microgram DNA in NIDDM patients, whereas the GS protein level was normal. The enzymatic activity and protein and mRNA levels of PFK were all normal in diabetic patients. In subgroups of NIDDM patients and control subjects an insulin-glucose clamp in combination with indirect calorimetry was performed. The rate of insulin-stimulated nonoxidative glucose metabolism was decreased by 47% (P < 0.005) in NIDDM patients, whereas the glucose oxidation rate was normal. The PFK activity, protein level, and mRNA/microgram DNA remained unchanged. The relative activation of GS by glucose-6-phosphate was 33% lower (P < 0.02), whereas GS mRNA/micrograms DNA was 37% lower (P < 0.05) in the diabetic patients after 4 h of hyperinsulinemia. Total GS immunoreactive mass remained normal. In conclusion, qualitative but not quantitative posttranslational abnormalities of the GS protein in muscle determine the reduced insulin-stimulated nonoxidative glucose metabolism in NIDDM.

Adult↗
PubMed1993

Suppression of GLUT4 expression in skeletal muscle of rats that are obese from high fat feeding but not from high carbohydrate feeding or genetic obesity.

In this study we determined whether alterations in the expression of GLUT4, the major insulin-regulatable glucose transporter, in skeletal muscle could explain the insulin-resistant glucose uptake characteristic of both dietary-induced and genetic obesity. GLUT1 expression was measured for comparison. To assess glucose transporter protein levels in dietary-induced obesity, postnuclear membranes were prepared from hindlimb muscle of Sprague-Dawley rats fed chow ad libitum (control), a high calorie/carbohydrate diet, or a high fat (80%) diet for 7 weeks. Immunoblotting revealed that GLUT4 protein levels decreased 34% in high fat-fed rats, but were unaltered in high calorie/carbohydrate-fed obese rats compared to control values. GLUT4 mRNA per DNA decreased 47% in muscle of high fat-fed rats compared to that in control or high calorie-fed rats; GLUT1 mRNA was reduced 31%, and actin mRNA tended to decrease (29%). To assess GLUT4 and GLUT1 expression in genetic obesity, similar studies were carried out in 5- and 20-week-old lean and obese Zucker rats as well as in 20-week-old obese Zucker rats 36 h after streptozotocin injection to lower insulin levels. GLUT4 protein and mRNA levels were unaltered in hindlimb muscle of obese Zucker rats at either age or in the acutely diabetic state, whereas GLUT1 protein and mRNA levels decreased 40-45%. Comparison of these results with recent data in adipocytes demonstrates tissue-specific regulation of expression of GLUT4 and GLUT1. Thus, obesity due to high fat feeding, but not that due to high calorie/carbohydrate feeding or genetics, is associated with pretranslational suppression of GLUT4 expression in skeletal muscle. In at least some forms of obesity, the level of GLUT4 expression in muscle appears to be only one factor in, or may even be unrelated to, the degree of insulin-responsive glucose transport in vivo.

Actins↗
PubMed1993

Expression of the major insulin regulatable glucose transporter (GLUT4) in skeletal muscle of noninsulin-dependent diabetic patients and healthy subjects before and after insulin infusion.

In a cross-sectional study we have examined the regulatory effect of insulin in vivo on the major insulin regulatable glucose transporter (GLUT4) in vastus lateralis muscle from 12 noninsulin-dependent diabetes mellitus (NIDDM) patients and 8 healthy control subjects. Insulin-stimulated glucose uptake rate in peripheral tissue was decreased by 41% (P < 0.01) in NIDDM patients compared to healthy subjects, whereas no significant differences could be shown in the abundance of total GLUT4 protein per DNA or GLUT4 messenger RNA (mRNA) per DNA among the 2 groups in muscle biopsies obtained in the basal state. In healthy subjects, 4 h of insulin infusion (2 mU/kg/min) induced a 31% reduction (P < 0.05) in the total GLUT4 protein content per DNA and a 35% increase (P < 0.05) in GLUT4 mRNA per DNA, whereas the GLUT4 mRNA and protein responses to insulin were heterogenous and statistically unaltered in the NIDDM patients. The GLUT4 protein per DNA of muscle obtained in the basal state correlated positively with the in vivo insulin-stimulated glucose uptake rate in the control group (r = 0.82, P < 0.05), whereas there was no comparable correlation in the NIDDM group (r = 0.05, P = 0.88). Furthermore, GLUT4 protein content in skeletal muscle after 4 h of insulin infusion did not correlate with insulin-stimulated glucose uptake in any of the groups. In conclusion, 4 h of insulin infusion causing supraphysiological serum insulin levels modulates the expression of GLUT4 in skeletal muscle from healthy subjects, with divergent effects at protein and mRNA levels. The physiological significance of these observations will have to be elucidated in future studies. Factors other than total GLUT4 protein content of muscle play a role in determining insulin-stimulated glucose uptake in human skeletal muscle.

Actins↗
PubMed1993

Expression of insulin receptor spliced variants and their functional correlates in muscle from patients with non-insulin-dependent diabetes mellitus.

Due to alternative splicing of exon 11 of the receptor gene, the human insulin receptor exists in two forms, that have distinct tissue-specific expression and are functionally different. Needle biopsies obtained from vastus lateralis muscle from 20 patients with noninsulin-dependent diabetes mellitus (NIDDM) and 20 normal control subjects were analyzed for the relative expression of insulin receptor mRNA variants in a novel assay using fluorescence-labeled primers and subsequent analysis on an automated DNA sequencer. In subgroups of patients and control subjects, insulin binding and tyrosine kinase activity were examined in wheat germ agglutinin-purified insulin receptors isolated from muscle biopsies. Moreover, insulin-stimulated glucose disposal was studied by means of the euglycemic hyperinsulinemic clamp technique. No difference in the relative expression of spliced variants of the insulin receptor mRNA was observed (control subjects, 71.4 +/- 1.3% insulin receptor mRNA with exon 11; NIDDM patients, 71.5 +/- 1.3% insulin receptor mRNA with exon 11). No significant interrelationships were demonstrated among the relative expression of insulin receptor mRNA variants, insulin binding, and tyrosine kinase activity toward the exogenous substrate poly(Glu-Tyr(4:1)). Furthermore, no significant relationship was demonstrated between the glucose disposal rate and the relative expression of insulin receptor splice variants. In conclusion, in skeletal muscle from both normal control subjects and NIDDM patients, the proportion of insulin receptor mRNA with exon 11 is about 70%. In addition, no significant correlations exist among insulin binding, insulin receptor tyrosine kinase activity, glucose disposal rate, and expression of alternative spliced insulin receptors in human skeletal muscle.

Adult↗
PubMed1993

Influence of short-term dexfenfluramine therapy on glucose and lipid metabolism in obese non-diabetic patients.

In a short-term (eight days) double-blind crossover study involving 10 obese patients, the effects of dexfenfluramine on glucose and lipid metabolism were examined. The protocol comprised whole body in vivo measurements (hyperinsulinemic euglycemic clamp in combination with indirect calorimetry) and in vitro studies of isolated adipocytes (lipolysis and glucose transport). All study participants were weight stable during the study period (103.1 +/- 3.2, placebo vs 103.3 +/- 3.1 kg, dexfenfluramine, NS). The following parameters were significantly reduced after dexfenfluramine treatment: fasting levels of plasma glucose (6.2 +/- 0.2 vs 5.7 +/- 0.2 mmol/l, p < 0.01), serum insulin (168.0 +/- 14.5 vs 138.9 +/- 7.9 pmol/l, p < 0.05), serum C-peptide (0.68 +/- 0.03 vs 0.58 +/- 0.02 nmol/l, p < 0.05) and total serum cholesterol (6.07 +/- 0.41 vs 5.48 +/- 0.38 mmol/l, p < 0.01). In the basal state glucose oxidation rate was significantly reduced by 36% (p < 0.001), whereas non-oxidative glucose disposal was significantly increased by 41% (p < 0.01), following dexfenfluramine treatment. Insulin-stimulated (2 mU.kg-1 x min-1) glucose disposal rate tended to be increased (18%, p = 0.10) after dexfenfluramine. In conclusion, dexfenfluramine possesses beneficial regulatory effects on glucose and lipid metabolism in non-diabetic obese patients, independently of weight loss.

Adipose Tissue↗
PubMed1992

[Insulin resistance--a physiopathological condition with numerous sequelae: non-insulin-dependent diabetes mellitus (NIDDM), android obesity, essential hypertension, dyslipidemia and atherosclerosis].

Recent research has demonstrated that reduced insulin-stimulated glucose metabolism in skeletal muscle (insulin resistance) and hyperinsulinism are common features in widespread diseases such as essential hypertension, android obesity, non-insulin dependent diabetes mellitus, dyslipidemia (in the form of raised serum triglyceride and reduced serum high-density lipoprotein (HDL) cholesterol) and arteriosclerosis. Simultaneously, investigations in a comprehensive group of healthy middle-aged men have revealed insulin resistance in one fourth. On the basis of these observations, a working hypothesis is suggested which postulates that genetic abnormalities in one or more of the candidate genes in the modes of action of insulin occur in a great proportion of the population. These may result in insulin resistance (primary genetic insulin resistance). Primary insulin resistance may be potentiated by a series of circumstances such as ageing, high-fat diet, lack of physical activity, hormonal and metabolic abnormalities or drugs (secondary insulin resistance). As a consequence of the reduced effect of insulin on muscle tissue, compensatory hyperinsulinism develops. Depending on the remaining vulnerability of the individual the hyperinsulinism is presumed to result in development of one or more phenotypes. For example if the beta-cells of the pancreas are unable to secrete sufficient insulin to compensate the insulin resistance on account of genetic defects, glucose intolerance will develop. In a similar manner, hyperinsulinism in insulin-resistant individuals who are predisposed to essential hypertension is presumed to reveal genetic defects in the blood pressure regulating mechanisms and thus contribute to development of the disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗