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L Groop

Publications and source records attributed to L Groop.

At least 91 records · Page 5Linked to original sources
PubMed1997

Characterization of the MODY3 phenotype. Early-onset diabetes caused by an insulin secretion defect.

Maturity-onset diabetes of the young (MODY) type 3 is a dominantly inherited form of diabetes, which is often misdiagnosed as non-insulin-dependent diabetes mellitus (NIDDM) or insulin-dependent diabetes mellitus (IDDM). Phenotypic analysis of members from four large Finnish MODY3 kindreds (linked to chromosome 12q with a maximum lod score of 15) revealed a severe impairment in insulin secretion, which was present also in those normoglycemic family members who had inherited the MODY3 gene. In contrast to patients with NIDDM, MODY3 patients did not show any features of the insulin resistance syndrome. They could be discriminated from patients with IDDM by lack of glutamic acid decarboxylase antibodies (GAD-Ab). Taken together with our recent findings of linkage between this region on chromosome 12 and an insulin-deficient form of NIDDM (NIDDM2), the data suggest that mutations at the MODY3/NIDDM2 gene(s) result in a reduced insulin secretory response, that subsequently progresses to diabetes and underlines the importance of subphenotypic classification in studies of diabetes.

Adult↗
PubMed1997

The effect of glycaemic control and the introduction of insulin therapy on retinopathy in non-insulin-dependent diabetes mellitus.

To study the progression of diabetic retinography in relation to diabetes treatment and glycaemic control in patients with non-insulin dependent (Type 2) diabetes mellitus (NIDDM), we performed a prospective study in a cohort of 1378 diabetic patients, aged > or = 40 years at diagnosis, of whom 333 were treated with insulin, and 1045 with oral antihyperglycaemic agents or diet alone. In the latter group 174 patients changed to insulin therapy during follow-up. We used the Wisconsin scale to grade retinopathy, recorded blindness (visual acuity < or = 0.1) and visual impairment (visual acuity 0.2-0.4), and measured the average HbA1c for each patient during a mean 3.1 year study period. In a multivariate analysis, patients who changed treatment from oral agents or diet alone to insulin therapy had a relative risk of 2.0 (95% confidence interval 1.7-2.3) for progression of retinopathy > or = 3 levels compared with all other patients in the study. The increase in risk remained even after controlling for mean HbA1c (relative risk 1.6; 95% confidence interval 1.3-1.9). Progression > or = 3 levels was significantly associated with a higher incidence of macular oedema and deterioration of visual acuity (p < 0.001). The relative risk for blindness/visual impairment due to retinopathy was 2.7 (95% confidence interval 1.8-4.0) in the group with changed treatment compared with all the other patients in the study. Poor glycaemic control (Hba1c%) before the start of insulin therapy and any retinopathy at baseline were significant risk factors for progression in the group with changed treatment (both p < 0.01). In the whole study group, poor glycaemic control was significantly associated with retinopathy progression > or = 3 levels; the relative risk for those having mean HbA1c above the median being 1.7 (95% confidence interval 1.4-2.1), compared to those with a HbA1c value below the median. Moderate non-proliferative diabetic retinopathy at baseline was also associated with progression (relative risk 2.5; 95% confidence interval 1.4-4.5). In contrast, insulin treatment at baseline was not associated with an increased risk of retinopathy progression. In conclusion, while hyperglycaemia was a risk factor for the progression of retinopathy in all patients, change of treatment from oral drugs to insulin was associated with a 100% increased risk of retinopathy progression and a 3-fold increased risk of blindness/visual impairment.

Administration, Oral↗
PubMed1997

Mortality in diabetic patients participating in an ophthalmological control and screening programme.

The aim of this follow-up study has been to assess retinopathy and change of treatment to insulin therapy as risk factors for mortality in diabetic patients participating in a control and screening programme for retinopathy. A total of 3220 diabetic patients, 483 with an age at diagnosis <30 years, and 2737 with an age at diagnosis > or = 30 years, were included. Retinopathy was graded on fundus photographs using the Wisconsin Scale, and the visual acuity was assessed. The average HbA1c value was calculated for each patient for the previous 8 years to estimate long-term glycaemic control. Mortality data were obtained from death certificates. Two hundred and sixty-three diabetic patients (8.2%) died during the mean follow-up time of 3.4 years, 13 (2.7%) of those with younger-onset (<30 years) and 250 (9.1%) of those with older-onset (> or = 30 years) diabetes. Of them, 148 (56.3%) died from cardiovascular and 23 (8.7%) from cerebrovascular disorders. After adjusting for differences in age and sex, more severe retinopathy and the use of antihypertensive drugs were associated with a decreased overall survival rate as well as an increased mortality from cardiovascular and cerebrovascular diseases. A statistically significant association between HbA1c values in the highest quartile, i.e. > or =8.4%, and cardiovascular and all cause mortality did not remain when retinopathy was entered into the multivariate analyses. Duration of diabetes, but not change of treatment to insulin therapy, was associated with higher cardiovascular mortality in patients whose diabetes was diagnosed after the age of 30 years. We conclude that severe retinopathy, use of antihypertensive drugs, and poor glycaemic control predicted death from cardiovascular disease in diabetic patients participating in an ophthalmological screening programme.

Adolescent↗
PubMed1997

Characterization of the prediabetic state.

First degree relatives of patients with non-insulin-dependent diabetes mellitus (NIDDM) have a 40% risk of developing NIDDM during their lifetime and the risk seems to be greater if the disease is inherited from the mother than from the father. It has also become clear that metabolic abnormalities are demonstrable long before the disease becomes manifest. The prediabetic state is associated with a predisposition to abdominal obesity, insulin resistance, lipid disorders, high blood pressure, and microalbuminuria, ie, the metabolic or insulin resistance syndrome. It is, however, not yet known whether treatment of these abnormalities is able to prevent progression to manifest NIDDM.

Diabetes Mellitus, Type 2↗
PubMed1996

The effect of (steroid) immunosuppression on skeletal muscle glycogen metabolism in patients after kidney transplantation.

To examine the mechanisms by which immunosuppression by steroids impairs glycogen synthesis in human skeletal muscle, we measured glycogen synthase protein content and activity in muscle samples from 14 patients receiving corticosteroid therapy after kidney transplantation and in 20 healthy control subjects. A percutaneous muscle sample was taken before and at the end of a euglycemic hyperinsulinemic insulin clamp. Insulin-stimulated glucose disposal was reduced by 33% in kidney transplant patients compared with healthy controls (33.8 +/- 4.2 vs. 50.5 +/- 2.7 mumol (kg LBM)-1 min-1; P<0.01), primarily due to a decrease in nonoxidative glucose metabolism (14.2 +/- 3.3 vs. 32.3 +/- 2.7 mumol (kg LBM)-1 min-1; P<0.001). Glycogen synthase activity measured at both 0.1 mmol/L (17.6 +/- 2.6 vs. 24.0 +/- 2.2 nmol min-1 mg protein-1; P<0.05), and at 10 mmol/L glucose 6-phosphate (24.1 +/- 3.5 vs. 33.7 +- 2.4 nmol min-1 mg protein-1; P<0.05) and glycogen synthase protein concentrations (8.8 +/- 1.8 vs. 18.9 +/- 1.9 relative units per ng DNA; P<0.01) were lower in kidney transplant patients compared with controls. Glycogen synthase protein correlated with nonoxidative glucose metabolism (r=0.42; P=0.04). Alpha-actinin (used as a control of general protein degradation) was lower in kidney transplant patients compared with controls (4.4 +/- 0.8 vs. 9.6 +/- 1.1 cpm/ng DNA; P<0.01). In conclusion, corticosteroids cause insulin resistance, which correlates with impaired activation of glycogen synthase and decreased enzyme protein content. The decrease in glycogen synthase protein may reflect increased degradation rather than a defect in translation.

Adult↗
PubMed1996

UKPDS 19: heterogeneity in NIDDM: separate contributions of IRS-1 and beta 3-adrenergic-receptor mutations to insulin resistance and obesity respectively with no evidence for glycogen synthase gene mutations. UK Prospective Diabetes Study.

Insulin receptor substrate-1 (IRS-1), beta 3-adrenergic-receptor (beta 3-AR) and glycogen synthase (GS) genes are candidate genes for non-insulin-dependent diabetes mellitus (NIDDM), insulin resistance, dyslipidaemia and obesity. We studied white Caucasian subjects with NIDDM, 227 being randomly selected, 49 NIDDM within the top two percentiles of insulin resistance; 54 with dyslipidaemia in the top quintile of triglyceride/insulin and the bottom quintile of HDL, and 166 non-diabetic control subjects. We examined the association of the simple tandem repeat DNA polymorphisms (STRPs) near the IRS-1 and GS genes, and the prevalence of mutations at codons of IRS-1 513 and 972, beta 3-AR 64 and GS 464 using restriction fragment length polymorphism (RFLP). The STRP alleles in IRS-1 were significantly different between NIDDM and control subjects (p = 0.015). The IRS-1 972 mutation was significantly different between the four groups with increased prevalence in the insulin resistant and dyslipidaemia subjects (18 and 26% compared with 11% in control subjects; p < 0.0005). Those with or without IRS-1 mutations had similar clinical characteristics and impaired insulin sensitivity. beta 3-AR 64 mutation was not significantly different between the four groups but those with the mutation were more obese, with a test for linear association between number of alleles and degree of obesity in an analysis of variance showing a significant association (p = 0.029). The GS 464 mutation was not detected in any of the diabetic or control subjects and the population association study using GS STRP showed no difference in allelic frequencies between NIDDM patients and control subjects. A mutation in lipoprotein lipase at codon 291, associated in the general population with low HDL cholesterol, was not at increased prevalence in the NIDDM patients with dyslipidaemia. In conclusion, IRS-1 972 had an increased prevalence in subjects with insulin resistance, with or without dyslipidaemia. beta 3-AR 64 was associated with increased obesity but not with insulin resistance or dyslipidaemia. These separate contributions to different features of NIDDM are an example of the polygenic inheritance of this heterogeneous disorder.

Adult↗
PubMed1996

Circulating TNF-alpha and leptin levels in offspring of NIDDM patients do not correlate to individual insulin sensitivity.

Obesity plays a central role in the development of skeletal muscle insulin resistance. The molecular mechanism causing skeletal muscle insulin resistance in obese people is still poorly understood. It has been speculated that circulating factors derived from adipose tissue impair insulin signalling in the skeletal muscle cell. TNF-alpha and leptin, which are overproduced in fat tissue of obese insulin resistant animal models and in obese humans, might mediate such an inhibitory effect on insulin signalling in skeletal muscle. The aim of the present study was to evaluate whether circulating TNF-alpha and leptin correlates to the individual skeletal muscle insulin sensitivity in individuals with different degrees of obesity and insulin resistance. We measured circulating TNF-alpha and leptin values in non diabetic offsprings of NIDDM patients. 36 German and 47 Finnish subjects participated in the study. The GDR of each participant was determined by the euglycemic hyperinsulinemic clamp technique, a range between 1.37 to 14.01 mg/kg LBM x min was observed. Percent of desirable body weight (PDW) covered also a wide range (87.58% to 197.06%). Although linear regression analysis suggested a dependence between TNF-alpha and GDR (Germany group: r = -0.37, p < 0.05, Finnish group: r = -0.32, p < 0.05) and a dependence between TNF and PDW (German group: r = 0.46, p < 0.05, Finnish group: r = 0.38, p < 0.05), in multiple linear regression analysis only the correlation with PDW was significant. Leptin levels were measured from 29 German and 36 Finnish subjects and a strong association was found between leptin and PDW (German group: r = 0.55, p < 0.05, Finnish group: r = 0.73, p < 0.05). In contrast, leptin levels did not correlate with GDR and TNF-alpha. In summary, even though, in a few insulin resistant subjects, higher circulating TNF-alpha or leptin levels with the individual insulin sensitivity can be demonstrated, the data suggest that the circulating pool of TNF-alpha and leptin in blood is unlikely to be a major contributing factor for obesity induced insulin resistance in the vast majority of individuals at high risk to develop NIDDM.

Adult↗
PubMed1996

Prevalence of diabetic retinopathy in relation to age at onset of the diabetes, treatment, duration and glycemic control.

To study the frequency of diabetic retinopathy in relation to age at diagnosis, treatment, duration of diabetes and glycemic control as measured by means of HbA1c levels, we performed a cross-sectional, registered-based study in the Helsingborg area of southern Sweden, comprising 2232 diabetic patients. Of the known diabetic population < 75 years old, approximately 70% were estimated to be included. We graded retinopathy according to the alternative classification of the Wisconsin study. With an age at diagnosis < 30 years (19% of patients) the prevalence of retinopathy was 64%, whereas with an age at diagnosis > or = 30 years the prevalence of retinopathy was 57% in insulin-treated, and 26% in non-insulin treated patients. Levels of glycated hemoglobin and duration of diabetes were associated with retinopathy in the group with younger onset. In the older-onset group, there was a relationship between retinopathy and duration of diabetes and insulin treatment; glycated hemoglobin had a relationship which was of borderline significance with any retinopathy, but clearly significant with the pooled group: severe non-proliferative, proliferative retinopathy and/or macular edema. Hyperglycemia and duration of diabetes were thus associated with retinopathy in both younger- and older-onset diabetes, but hyperglycemia less so in the older-onset group.

Adult↗
PubMed1996

Progression of retinopathy is related to glycaemic control even in patients with mild diabetes mellitus.

To study the progression of retinopathy in patients with mild diabetes mellitus, we examined, in a cohort study, 347 patients treated with diet alone at baseline. The patients participated in an ophthalmological screening and control programme, and diet-treated patients who were examined between January 1990 and July 1992 were included in the study and followed until October 1995. Mean follow-up was 3.4 +/- 1.1 years. The alternative classification of the Wisconsin study was used to classify retinopathy, and the mean HbA1c values for the study period, to estimate the level of glycaemic control. At baseline, 314 of the patients (90.5%) had no retinopathy, and 33 (9.5%) had mild non-proliferative diabetic retinopathy. In 296 patients there was no retinopathy progression, in 27 patients there was progression by 1 level in the retinopathy scale, and in 24 patients by 2 levels or more. In 2 patients there was progression to proliferative diabetic retinopathy. The mean HbA1c (%) was 6.5 +/- 1.3. Higher HbA1c correlated to increased progression (r = 0.16; p = 0.005), and in a multivariate analysis, HbA1c remained associated with a progression of retinopathy by 2 levels or more, with a relative risk of 1.4 per percent increase in HbA1c (95% CI 1.1-2.0; p = 0.02). Furthermore, the presence of any retinopathy at baseline was associated with progression with a relative risk of 1.7 (95% confidence interval 1.1-2.8; (p = 0.02). These data indicate that even slightly elevated levels of HbA1c might be associated with a risk of retinopathy progression.

Adult↗
PubMed1996

Metabolic consequences of a family history of NIDDM (the Botnia study): evidence for sex-specific parental effects.

Although a strong genetic susceptibility has been established for NIDDM and a maternal transmission of the disease predominates in some populations, a relationship between parental diabetes status and metabolic abnormalities in nondiabetic offspring has not been shown in humans. To address this question, we studied 2,152 first-degree relatives of patients with NIDDM (FH+) and 528 age- and weight-matched spouses without a family history of NIDDM (FH-) in Western Finland (the Botnia study). A subset of the subjects underwent a euglycemic insulin clamp combined with indirect calorimetry to measure insulin sensitivity and energy expenditure. Despite similar amounts of total body fat, persons with a family history of NIDDM had a greater waist-to-hip ratio (WHR) than spouses without a family history of diabetes (P < 0.003). They also had a decreased resting metabolic rate (P = 0.005), but this difference disappeared when adjusted for the difference in WHR. Insulin-stimulated glucose metabolism (P = 0.002), particularly nonoxidative glucose metabolism (P = 0.009), was reduced in FH+ compared with FH- subjects, and this difference remained after adjustment for WHR. A parental history of NIDDM influenced the insulin response to the oral glucose load, with male offspring of diabetic mothers showing the lowest insulin values (P = 0.011). Moreover, a parental effect was also observed on HDL and HDL2 cholesterol concentrations with female offspring of diabetic mothers showing lower values than female offspring of diabetic fathers (both P < 0.002). We conclude that abdominal obesity, insulin resistance, and decreased resting metabolic rate are characteristic features of first-degree relatives of patients with NIDDM and that the decrease in resting metabolic rate is partially related to the degree of abdominal obesity. A sex-specific paternal effect was observed on insulin and HDL cholesterol concentrations. Therefore, one has to consider the possibility of unprecedented maternal or paternal inheritance of different NIDDM phenotypes.

Apolipoproteins↗
PubMed1996

Hyperinsulinemia and insulin resistance are associated with multiple abnormalities of lipoprotein subclasses in glucose-tolerant relatives of NIDDM patients. Botnia Study Group.

We studied the subclasses of plasma lipoproteins in normolipidemic, glucose-tolerant male relatives of noninsulin dependent diabetic patients (NIDDM), who represented either the lowest (n = 14) or the highest (n = 18) quintiles of fasting plasma insulin. The higher plasma triglyceride level in the high insulin group (1.61 mmol/l vs. 0.87 mmol/l, P < 0.001) was due to multiple differences in triglyceride-rich lipoproteins. The concentrations of larger VLDL1, smaller VLDL2 particles, and IDL particles were 3.8-fold, 2.5-fold, and 1.5-fold higher, respectively, in the high insulin group than in the low insulin group (P < 0.01 or less). In addition, hyperinsulinemic subjects had VLDL1, VLDL2, and IDL particles enriched in lipids and poor in protein. The lower plasma HDL cholesterol level in the high insulin group (1.20 mmol/l vs. 1.44 mmol/l, P < 0.01) compared to the low insulin group was a consequence of a 27% reduction of HDL2a concentration (P < 0.05) and a significantly reduced percentage of cholesterol in HDL3a, HDL3b, and HDL3c subclasses. On the other hand, the percentages of triglycerides in HDL2b, HDL2a, HDL3a, and HDL3b subclasses were 76%, 79%, 61%, and 50% higher, respectively, in the high insulin group than in the low insulin group (P < 0.01 or less). In the combined group, the concentration of VLDL1 and VLDL2 correlated positively with the concentrations of LDL2 and LDL3 and negatively with HDL2b and HDL2a subclasses (P < 0.05 or less). In conclusion, normolipidemic, glucose-tolerant but hyperinsulinemic relatives of NIDDM patients have qualitatively similar lipoprotein abnormalities as NIDDM patients. These abnormalities are not observed in insulin-sensitive relatives, suggesting that they develop in concert with insulin resistance.

Adult↗
PubMed1995

Human hexokinase II gene: exon-intron organization, mutation screening in NIDDM, and its relationship to muscle hexokinase activity.

In muscle, hexokinase II (HK2) regulates phosphorylation of glucose to glucose 6-phosphate, which has been reported to be impaired in patients with non-insulin-dependent diabetes mellitus (NIDDM). Here we report decreased HK2 enzyme activity in skeletal muscle biopsies from patients with impaired glucose tolerance compared with healthy control subjects (2.7 +/- 0.9 vs 4.9 +/- 1.1 nmol.min-1.mg protein-1). Therefore, mutations in the HK2 gene could contribute to skeletal muscle insulin resistance in NIDDM. To address this question, we first determined the exon-intron structure of the human HK2 gene and using this information, we screened all 18 exons with single-strand conformation polymorphism technique in 80 Finnish NIDDM patients. Nine nucleotide substitutions were found, one of which was a missense mutation (Gln142-His142) in exon 4. In human muscle, a single HK2 mRNA transcript with a size of approximately 5500 nucleotides was detected with Northern blot analysis. We also describe an HK2 pseudogene (HK2P1), which was mapped to chromosome 4, band q26, by fluorescence in situ hybridization to metaphase chromosomes. The clinical characteristics and HK2 enzyme activities of the subjects with either Gln or His at residue 142 did not differ from each other. Instead, HK2 activity correlated inversely with fasting blood glucose levels, suggesting that changes in HK2 activity could be secondary to other metabolic abnormalities (r = 0.55; p < 0.0003; n = 39). In conclusion; the data suggest that impaired HK2 activity in prediabetic individuals is a consequence of impaired glucose tolerance rather than of a genetic abnormality. The data thus seem to rule out mutations in the HK2 gene as a major cause of inherited insulin resistance in NIDDM.

Aged↗
PubMed1995

Changes of lipolytic enzymes cluster with insulin resistance syndrome. Botnia Study Group.

The activities of hepatic and lipoprotein lipase and the levels of lipo- and apoproteins were compared in two groups of normoglycaemic men representing the highest (n = 18) and lowest (n = 15) fasting insulin quintiles of first degree male relatives of non-insulin-dependent diabetic patients. The high insulin group representing insulin-resistant individuals had significantly lower post-heparin plasma lipoprotein lipase activity than the low insulin group (14.2 +/- 4.0 vs 20 +/- 5.8 mumol NEFA.ml-1.h-1, p < 0.001); hepatic lipase activity did not differ between the two groups (24.2 +/- 11 vs 18.0 +/- 5.3 mumol NEFA.ml-1.h-1, NS). The lipoprotein lipase/hepatic lipase ratio in the high insulin group was decreased by 66% as compared to the low insulin group (0.75 +/- 0.57 vs 1.25 +/- 0.65, p < 0.01). In the high insulin group both total and VLDL triglycerides were higher than in the low insulin group (1.61 +/- 0.57 vs 0.86 +/- 0.26 mmol/l, p < 0.001 and 1.00 +/- 0.47 vs 0.36 +/- 0.16 mmol/l, p < 0.001, respectively) whereas HDL cholesterol and HDL2 cholesterol were lower (1.20 +/- 0.30 vs 1.43 +/- 0.22 mmol/l, p < 0.05 and 0.49 +/- 0.21 vs 0.71 +/- 0.17 mmol/l, p < 0.05, respectively). Total cholesterol, LDL cholesterol or HDL3 cholesterol did not differ between the two groups. The mean particle size of LDL was smaller in the high insulin group than in the low insulin group (258 +/- 7 vs 265 +/- 6 A, p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1995

Lack of association between the Gly40Ser polymorphism in the glucagon receptor gene and NIDDM in Finland.

A heterozygous polymorphism changing GGT40 (Gly) to AGT40 (Ser) (Gly40Ser) in the glucagon receptor gene was reported to be associated with non-insulin-dependent diabetes mellitus (NIDDM). A possible involvement of this polymorphism in impaired glucose tolerance was also suggested in a French population. To replicate this finding we screened 311 unrelated NIDDM patients, 101 unrelated individuals with impaired glucose tolerance and 306 control subjects for the presence of the Gly40Ser polymorphism by use of polymerase chain reaction-restriction fragment length polymorphism in a Finnish population. None of the NIDDM or impaired glucose tolerant patients had this polymorphism. Instead, four of the control subjects (1.3%) were heterozygous carriers of the polymorphism (NS). The age, body mass index, 2-h blood glucose level, 2-h insulin level, and incremental insulin are of the four subjects with this polymorphism were similar to those of the control subjects homozygous for the wild type. Taken together, the data do not support the suggested involvement of the Gly40Ser polymorphism in impaired glucose tolerance and the hypothesis of an association between NIDDM and the glucagon receptor gene in this population.

Alleles↗
PubMed1995

A novel mechanism of glipizide sulfonylurea action: decreased metabolic clearance rate of insulin.

To examine whether sulfonylureas inhibit the metabolic clearance rate (MCR) of insulin, 19 healthy young subjects participated in two experiments. In the first protocol (n = 10), a 3-h oral glucose load was performed with and without 2 mg of glipizide given 30 min before glucose ingestion. The total insulin response was 60% greater with than without glipizide (5.9 +/- 0.6 vs 3.7 +/- 0.5 microU/ml; P < 0.001). However, the total C-peptide responses were virtually identical (4.7 +/- 0.5 vs 4.8 +/- 0.4 nmol/l) in both studies. In the second protocol (n = 9), the MCR of insulin was measured during 4-h euglycemic insulin clamps performed with and without glipizide. In the study with glipizide, the subjects ingested 5 mg of glipizide at 120 min. The steady-state plasma insulin concentration during the 4th h, i.e., 1-2 h after glipizide ingestion, was significantly higher than during the 2nd h, i.e., before glipizide ingestion (99 +/- 22 vs 78 +/- 17 microU/ml; P < 0.01). In addition, glucose uptake during the 4th h was greater (8.0 +/- 1.6 vs 6.4 +/- 1.5 mg/kg.min) and the MCR of insulin was reduced (503 +/- 126 vs 621 +/- 176 ml/m2.min; P < 0.01). We conclude that glipizide augments plasma insulin levels both by enhancing its secretion and by decreasing the MCR of insulin.

Adult↗
PubMed1995

Increased concentrations of glycogen synthase protein in skeletal muscle of patients with NIDDM.

To examine whether changes in the glycogen synthase protein concentration contribute to impaired insulin-stimulated glycogen metabolism in patients with noninsulin-dependent diabetes mellitus (NIDDM), muscle biopsies were taken before and after a 4-h euglycemic hyperinsulinemic clamp to measure glycogen synthase activity and glycogen synthase protein concentrations in 14 patients with NIDDM and in 17 control subjects. Nonoxidative glucose metabolism was reduced by 64% in patients with NIDDM compared with control subjects and correlated with insulin-stimulated glycogen synthase activity (r = 0.55, P < 0.05). The concentration of glycogen synthase protein in skeletal muscle was higher in patients with NIDDM than in control subjects (6.75 +/- 0.88 vs. 4.41 +/- 0.50 counts.min-1.micrograms protein-1, P < 0.05), whereas there was no significant difference in glycogen synthase mRNA concentration between the two groups. The glycogen synthase protein concentration correlated inversely with the rate of nonoxidative glucose metabolism (r = -0.63, P < 0.05). These findings indicate that the amount of glycogen synthase protein is increased in skeletal muscle of patients with NIDDM. The increase in the glycogen synthase protein may serve to compensate for a functional defect in the activation of the enzyme by insulin.

Blood Glucose↗
PubMed1995

A recurring dominant negative mutation causes autosomal dominant growth hormone deficiency--a clinical research center study.

Familial isolated GH deficiency type II (IGHD-II) is an autosomal dominant disorder that has been previously shown in some patients to be caused by heterogeneous GH gene defects that affect GH messenger RNA (mRNA) splicing. We report here our finding of multiple G-->A transitions of the first base of the donor splice site of IVS 3 (+ 1G-->A) in IGHD II subjects from three nonrelated kindreds from Sweden, North America, and South Africa. This + 1G-->A substitution creates an NlaIII site that was used to demonstrate that all affected individuals in all three families were heterozygous for the mutation. To determine the effect of this mutation on GH mRNA processing, HeLa cells were transfected with expression plasmids containing normal or mutant + 1G-->A alleles, and complementary DNAs from the resulting GH mRNAs were sequenced. The mutation was found to destroy the GH IVS 3 donor splice site, causing skipping of exon 3 and loss of the codons for amino acids 32-71 of the mature GH peptide from the mutant GH mRNA. Our finding of exon 3 skipping in transcripts of the + 1G-->A mutant allele is identical to our previous report of a different sixth base transition (+6T-->C) mutation of the IVS 3 donor splice site that also causes IGHD II. Microsatellite analysis of an affected subjects' DNA from each of the three nonrelated kindreds indicates that the + 1G-->A mutation arose independently in each family. Finding that neither grandparent has the mutation in the first family suggests that it arose de novo in that family. Our data indicate that 1) + 1G-->A IVS 3 mutations perturb GH mRNA splicing and cause IGHD II; and 2) these mutations can present as de novo GHD cases.

Adult↗