A gel electrophoresis method for detection of mitochondrial DNA mutation (3243 tRNA(Leu (UUR))) applied to a Norwegian family with diabetes mellitus and hearing loss.

Blood cells of selected patients from a large Norwegian family with maternally transmitted diabetes mellitus, hearing loss and muscular dysfunction were screened for possible A3243G mutation tRNA(Leu (UUR)) in mitochondrial DNA. We selected 7 patients from 3 of the 4 generations of the family and 10 unrelated healthy control subjects for mutation analysis using denaturing gradient gel electrophoresis (DGGE) and both manual and automated DNA sequencing. The A3243G mutation was found in peripheral blood cells of all 7 patients, but in none of the controls. The mutation was in the form of heteroplasmy and the amount of mutant DNA was found to be between 10% and 35% of total mtDNA in individual patients. This is the first report of a Norwegian family with maternally inherited diabetes and hearing loss carrying the A3243G mutation in mitochondrial DNA.

Disposition of homocysteine in subjects heterozygous for homocystinuria due to cystathionine beta-synthase deficiency: relationship between genotype and phenotype.

We have investigated 31 subjects from five unrelated families with one or more members with cystathionine beta-synthase (CBS) deficiency. On the basis of their CBS genotype, the subjects were grouped as normal (n = 11) or heterozygotes (n = 20). Based on pyridoxine effect in the probands, the heterozygotes were further classified as pyridoxine-responsive (n = 9) or non-responsive (n = 11). Heterozygous subjects had normal fasting total plasma homocysteine (tHcy), but median urinary tHcy excretion rate was significantly elevated compared to healthy controls (0.39 micromol/h vs 0.24 micromol/h, P < 0.05). An abnormal tHcy response after methionine loading identified 73% of the pyridoxine non-responsive heterozygotes, but only 33% of the pyridoxine responsive participants. The increase in cystathionine or the change in tHcy relative to cystathionine did not improve diagnostic accuracy of the methionine loading test. After Hcy loading, the maximal increase in tHcy was significantly elevated, whereas t(1/2) was normal in heterozygotes. In conclusion, a single biochemical test cannot discriminate CBS heterozygotes from controls. Abnormal tHcy response after methionine loading was the most sensitive test. Our data suggest that the urinary tHcy excretion rate is a simple, non-invasive approach for studying mild disturbances in Hcy metabolism.

[New diagnostic criteria for diabetes mellitus--why?]. / Nye diagnostiske kriterier for diabetes mellitus--hvorfor?

In 1997, the diagnostic criteria for diabetes mellitus were changed in the USA; the WHO has also proposed changes in its criteria. The main difference from the previous set of WHo criteria is a lowering of the cut-off level of fasting plasma glucose to > or = 7.0 mmol/l. This article discusses the implications of new diagnostic criteria and recommends that the level of fasting plasma glucose for diagnosing diabetes is decreased to > or = 7.0 mmol/l in Norway as well.

The effect of smoking on glucose homeostasis and fetal growth in pregnant women.

OBJECTIVE: To examine the relationship between maternal blood glucose levels, cigarette smoking in pregnancy and fetal growth. DESIGN: A prospective study of healthy parous women from early pregnancy and their infants. SETTING: Three Scandinavian university hospitals covering all deliveries from well defined geographical areas. SUBJECTS: Study groups of non-smoking (150), light smoking (131) and heavily smoking mothers (218), para 1 and 2 and with > 37 weeks of gestational length. MAIN OUTCOME MEASURES: Oral glucose tolerance test performed in pregnancy week 37, glycated hemoglobin measured the 3rd day post partum and neonatal anthropometric parameters including skinfold measurements. RESULTS: Among heavily smoking mothers 12.4% displayed a 2-hour glucose value in the range of gestational diabetes (> 8.5 mmol/l) compared to 9.2% among light smokers and 6.0% among nonsmokers (p < 0.05). Heavily smoking mothers also had significantly (p < 0.05) higher glycated hemoglobin compared to nonsmokers, 5.01 v.s. 4.86. These changes in glucose parameters in smokers were not associated with higher birthweights. CONCLUSIONS: Smoking in pregnancy affects parameters of glucose homeostasis in the direction of gestational diabetes. The retarding effect of smoking on fetal growth abolished any expected growth stimulation from the higher blood glucose levels seen in the smokers.

Evidence for dissociation of insulin- and weight-reducing effects of metformin in non-diabetic male patients with coronary heart disease.

Metformin effects on insulin resistance and insulin/glucose relationships during an oral glucose tolerance test (OGTT) were investigated in 60 non-diabetic male patients previously treated with coronary artery bypass surgery or angioplasty in an open, 12 week prospective study. During a 4 week run-in period, all patients were treated with diet and lifestyle advice and lovastatin 40 mg daily. Lovastatin treatment was continued in all the patient throughout the study. After randomization, the metformin group got additional treatment with metformin up to 2000 mg/day. Fasting plasma glucose levels and glucose area during OGTT remained unaffected by metformin treatment. Insulin resistance, assessed as the insulin area/glucose area ratio during OGTT decreased by 24% (P = 0.028) in the whole group and by 30% in obese subjects (P = 0.049). Notably, the reduction in body weight by metformin treatment did not correlate with amelioration of insulin resistance or changes in lipid levels. However, changes in insulin resistance correlated with changes in lipid levels. Hence, metformin effects on insulin resistance and body weight appear to be mediated, at least partly, by different mechanisms, while metformin effects on insulin resistance and lipid metabolism are associated in non-diabetic subjects.

[Non-insulin dependent diabetes in children and adolescents]. / Ikke-insulinkrevende diabetes hos barn og unge.

Maturity-onset diabetes of the young (MODY) is a clinically and genetically heterogenous disorder characterized by autosomal dominant inheritance with onset usually before 25 years of age, and a primary defect in glucose-stimulated insulin secretion. Genetic analyses have shown that mutations in at least five different genes can cause MODY. These are the genes encoding the glycolytic enzyme glucokinase, three liver-enriched transcription factors, hepatocyte nuclear factor (HNF)-1 alpha, HNF-1 beta and HNF-4 alpha, and the gene encoding the transcription factor, insulin promoter factor-1 (IPF-1). Patients with MODY3 run a considerable risk of developing diabetic eye disease. MODY2, related to glucokinase deficiency, is a relatively benign disorder which does not usually require insulin. Experiences with the three other MODY forms have so far been restricted to very few families. We present the first Norwegian family with MODY2. Furthermore, a previously published Norwegian family is shown to be MODY3. Subjects who fulfil the criteria of MODY can, by genetic testing, gain information important for prognosis and perhaps also for therapy.

Metformin increases circulating tumour necrosis factor-alpha levels in non-obese non-diabetic patients with coronary heart disease.

Metformin reduces insulin resistance and hyperinsulinaemia, as well as lipid levels and body weight. The mechanisms behind these effects are likely to involve intracellular insulin signalling. Recent evidence implicates tumour necrosis factor-alpha (TNF-alpha) as a modulatory factor on insulin resistance. The present investigation was undertaken to clarify whether metformin affects TNF-alpha and soluble TNF receptor levels. Sixty non-diabetic men with coronary heart disease were treated with diet and lifestyle advice and lovastatin 40 mg/day during a 4-week run-in period. During this period TNF-alpha and soluble TNF receptor p75 remained unchanged, whereas soluble TNF receptor p55 increased by 8% (P < 0.05). Twelve weeks of metformin treatment increased TNF-alpha by 33% (P < 0.05). This effect was restricted to non-obese patients in whom TNF-alpha increased by 68% (P < 0.01). Soluble TNF receptors p55 and p75 remained unchanged in the whole group, whereas soluble TNF receptor p55 increased by 11% (P < 0.05) in non-obese patients. Since metformin reduces insulin resistance both in obese and non-obese subjects but increases TNF-alpha levels only in the latter, it is concluded that the drug does not exert its effect on insulin resistance through regulation of circulating TNF-alpha levels.

Metformin increases total serum homocysteine levels in non-diabetic male patients with coronary heart disease.

It is known that the metabolism of homocysteine (Hcy) depends on the vitamins B6, B12 and folate, and furthermore that metformin reduces serum vitamin B12 levels. In order to investigate whether metformin treatment affects serum total Hcy (tHcy) levels we performed an open, prospective, randomised study in 60 non-diabetic male patients with cardiovascular disease. After a 4-week run-in period with lovastatin 40 mg day-1, and diet and lifestyle advice, patients were randomised into two groups, both continuing the run-in treatment. One group received metformin up to 2000 mg day-1, whereas the control group got no additional treatment. After 12 and 40 weeks of metformin treatment, tHcy levels increased moderately but significantly by 7.2% (p < 0.05) and 13.8% (p < 0.05) in the metformin group relative to the control group, whereas serum vitamin B12 levels decreased by 13.4% (p < 0.0005) and 17.7% (p < 0.0005), respectively. Serum folate levels did not change after 12 weeks, but decreased by 8.0% after 40 weeks (p = 0.061) relative to the control group. Serum levels of total cysteine and methylmalonic acid (MMA) did not change. In conclusion, metformin treatment increased tHcy levels and decreased levels of vitamin B12 and folate. Since MMA levels were unchanged, it remains an open question whether the increase in tHcy levels is secondary to reduced vitamin B12 levels, folate levels or a combination of both.

Functional modeling of vitamin responsiveness in yeast: a common pyridoxine-responsive cystathionine beta-synthase mutation in homocystinuria.

Cystathionine beta-synthase (CBS) deficiency is an autosomal recessive disorder which results in extremely elevated levels of total plasma homocysteine (tHcy) and high risk of thromboembolic events. About half of all patients diagnosed with CBS deficiency respond to pyridoxine treatment with a significant lowering of tHcy levels. We examined 12 CBS-deficient patients from 10 Norwegian families for mutations in the CBS gene and identified mutations in 18 of the 20 CBS alleles. Five of the seven patients classified as pyridoxine-responsive contain the newly identified point mutation, G797A (R266K). This point mutation is tightly linked with a previously identified 'benign' 68 bp duplication of the intron 7-exon 8 boundary within the CBS gene. We tested the effect of all of the mutations identified on human CBS function utilizing a yeast system. Five of the six mutations had a distinguishable phenotype in yeast, indicating that they were in fact pathogenic. Interestingly, the G797A allele had no phenotype when the yeast were grown in high concentrations of pyridoxine, but a severe phenotype when grown in low concentrations, thus mirroring the behavior in humans. These studies show that the G797A mutation is an important cause of pyridoxine-responsive CBS deficiency and demonstrate the utility of yeast functional assays in the analysis of human mutations.

TNF production from peripheral blood mononuclear cells in diabetic patients after stimulation with alginate and lipopolysaccharide.

Microencapsulated pancreatic Langerhans islets in calcium alginate gels have been used as an implantable bio-artificial pancreas in the treatment of diabetes mellitus, but with limited success due to overgrowth of the capsule with fibroblasts and phagocytes. The authors earlier demonstrated that alginates enriched in mannuronic acid stimulate human monocytes to produce high levels of cytokines such as tumour necrosis factor (TNF), IL-1 IL-6. In this study the authors have measured the TNF production from peripheral blood mononuclear cells (PBMC) in different groups of insulin-dependent diabetes mellitus (IDDM) patients after stimulation with different alginates and lipopolysaccharide (LPS). It was found that high G-alginate did not induce TNF production in any of the groups. High-M alginate and LPS induced a dose-dependent TNF production in all groups and the production was significantly different from unstimulated cells. The highest TNF response was found in newly diagnosed IDDM patients and the lowest was in the controls.

Metformin improves blood lipid pattern in nondiabetic patients with coronary heart disease.

OBJECTIVES: To study whether the addition of metformin further improves the blood lipid pattern in non-diabetic patients with coronary heart disease already treated with lovastatin, diet and lifestyle advice. DESIGN: An open, prospective, randomized study in a university hospital setting. SUBJECTS: Sixty non-diabetic male patients previously treated with coronary artery bypass surgery or angioplasty and with serum cholesterol > or = 6.0 mmol L-1 and/or HDL-cholesterol < or = 1.2 mmol L-1. INTERVENTIONS: After a 4-week run-in period with lovastatin (40 mg day-1), and diet and lifestyle advice, patients were randomized into two groups, both continuing the run in treatment. One group received metformin up to 2000 mg day-1; the control group got no additional treatment. MAIN OUTCOME MEASURES: Fasting serum lipids, glucose and weight were registered at entrance (= week-4), and at weeks 0, 4 and 12. Changes from week 0 to week 4 and from week 0 to week 12 were compared. Side-effects of the treatment were also registered. RESULTS: Metformin lowered the LDL/HDL-cholesterol ratio by 12 and 6% at weeks 4 and 12, respectively, and reduced body weight by 1.8 kg at week 12. There was also a transient lowering effect on LDL-cholesterol and apolipoprotein B. In the normal weight subgroup of patients (body mass index < 27 kg m-2), metformin induced a decrease in total cholesterol (-9%). LDL-cholesterol (-12%). LDL/HDL-cholesterol ratio (-10%) and apolipoprotein B (-7%), as compared to the control group. In this subgroup, body weight and fasting glucose were unaffected by metformin. Thus, the lipid lowering effect in normal weight patients was not secondary to changes in body weight or fasting glucose. In overweight patients (body mass index > 27 kg m-2), metformin had no significant effects on blood lipids, but induced a weight loss of -3.0 kg and a transient reduction of fasting glucose. No side-effects were registered apart from those expected from each individual drug. CONCLUSIONS: Metformin given for 12 weeks as a supplement to lovastatin, diet and lifestyle advice to non-diabetic male patients with coronary heart disease further improves the lipid pattern in normal weight patients, and reduces weight in the overweight patients. Because metformin is cheap and other lipid lowering drugs are expensive, the potential of metformin as a lipid lowering agent should be further investigated.

Pharmacokinetics of transperitoneal insulin transport.

Seven type I insulin-dependent diabetic patients on continuous ambulatory peritoneal dialysis treatment were selected for this study. Each patient participated in three different 6-hour 'single-dwell' studies on 3 consecutive days. A mean dose of 33 +/- 1.3 U Insulin Actrapid Human was given intraperitoneally each day. The procedures for intraperitoneal insulin administration were: (1) with 1,000 ml Ringer lactate; (2) with 1,000 ml 3.86% glucose-containing dialysate, and (3) into an empty peritoneal cavity. The calculation of the intraperitoneal volume was done with a single injection indicator dilution technique in which 100 kBq radioiodinated serum albumin (RISA) was added into the fluid prior to instillation. Free insulin and glucose were analyzed at 16 time intervals in blood and in dialysate during each dwell. After drainage the peritoneal cavity was rinsed with 1,000 ml Ringer lactate followed by two consecutive 5-hour exchanges with 2,000 ml glucose-containing dialysate. Recovery of insulin and RISA was measured in rinsing fluid and in sampled dialysate during the 6-hour dwell. The kinetic calculations made for insulin were disappearance rate (mU/min) from the peritoneal cavity, and appearance rate in circulating blood. After drainage and rinsing, 66.0 +/- 10 and 71.8 +/- 9.8% of the insulin instilled had disappeared after 6 h from the glucose fluid and from the Ringer solution respectively and did not differ significantly. However, the estimated disappearance rate from the peritoneal cavity was significantly higher in Ringer than in glucose from the time interval 120 to 360 min. A high and peak-shaped insulin concentration in the plasma was found following insulin injection into an empty peritoneal cavity, and was significantly higher than when insulin was dissolved in a 1,000-ml fluid volume. However, a higher blood concentration was also found when Ringer was instilled than when a hyperosmolal glucose solution was instilled. A high first-pass elimination in the liver is suggested. In conclusion, fluid volume and also the osmolality of the solution in the peritoneal cavity decreases the transport rate, but not the bioavailability of insulin given intraperitoneally. Both a high peak shape and a continuous insulin appearance in blood can be achieved. It is suggested that there is a high first-pass elimination of insulin during absorption from the peritoneal cavity. However, the values are uncertain and extended investigations must be done.

The discovery of phenylketonuria.

In 1934, two severely mentally retarded children were examined by Dr Asbjørn Følling. He proved, by classical organic chemistry, that they excreted phenylpyruvic acid in their urine. The substance was also found in the urine of eight additional mentally retarded patients. Based on these observations, oligophrenia phenylpyrouvica (later termed phenylketonuria) was described as a new inborn error of metabolism. Følling later showed the pattern of an autosomal recessive genetic disease, probably caused by a block in phenylalanine metabolism, and that asymptomatic heterozygote carriers of the trait could be detected by phenylalanine loading. The stepwise elucidation and the line of reasoning are described. Phenylketonuria was the first inborn error of metabolism shown to affect the mind, and its importance as a model disease is emphasized. The article finally gives some insight into aspects of the personality of the discoverer.

[Metformin reevaluated--time for rehabilitation?]. / Metformin revurdert--tid for rehabilitering?

The consumption of metformin in Norway is low. Most probably this is caused by poorly based impressions of small effects and frequent and serious side effects. A review of the literature shows that metformin and sulfonylurea lower average blood glucose values equally well, both in obese and non-obese type 2 diabetic patients. In sulfonylurea failure, addition of metformin lowers the glucose values to the same extent as a shift to insulin monotherapy does. Metformin is anti-hyperglycaemic only, and therefore does not cause hypoglycaemia. The risk of drug-related deaths is no higher with metformin than with sulfonylurea. Metformin improves the lipid profile, and has other effects which could lower risk of cardiovascular complications. The place of metformin in the treatment of type 2 diabetic patients should be reconsidered.

Increased magnesium in aqueous humour from patients with senile cataract.

A previous observation of increased aqueous magnesium in eyes with senile cataract has been re-examined in a totally different material. The serum and aqueous level of calcium and magnesium from 34 patients with senile cataract were tested against comparable values from 4 patients with choroidal melanoma. In contrast to calcium, the magnesium aqueous/serum ratio was significantly higher in the cataract group. Possible explanations are suggested.

Hormonal and biochemical disturbances in Down's syndrome.

Clinical and laboratory endocrine variables in 29 adult institutionalized patients with Down's syndrome were compared with those of matched controls consisting of other mentally retarded patients from the same institution. Of the clinical variables, testes volume and body height were significantly lower in patients with Down's syndrome than in control patients. The thyroid function tests documented a higher average TSH level in Down's syndrome than in other mentally retarded patients. However, there was no clear-cut correlation between TSH and thyroid hormone levels. The data indicate that there is a tendency towards primary thyroid dysfunction in Down's syndrome. In addition, there is some evidence indicating a relative failure of TSH secretion. In male patients, estradiol was elevated compared to controls. FSH and LH also seemed slightly higher in the study group, but the differences only reached statistical significance when patients on chronic medication were omitted. Prolactin was significantly greater in the Down's syndrome patients than in the controls, both over the entire sample and in the subgroup of men with Down's syndrome, with P-values of around 0.001. The elevation of prolactin was not due to medication and did not correlate to thyroid function or difficulties during blood sampling. In females, the difference was not statistically significant. Laboratory tests that may be associated with endocrine disease or might indicate disease which could influence the endocrine status, were also included in this study. Compared with the controls, ESR, creatinine and uric acid levels were higher in Down's syndrome patients, while albumin was lower, all with P-values lower than 0.001. Vitamin B12 was moderately lower in Down's syndrome patients than in controls (P less than 0.05).

Somatomedin C (insulin-like growth factor 1) in adults with Down's syndrome.

In a Norwegian institution for the mentally retarded, 29 adults with chromosomally verified Down's syndrome were compared to other mentally retarded patients with respect to serum somatomedin C (SmC) (insulin-like growth factor 1 [IGF-1]). Contrary to what has been observed in children, no shortage of SmC could be demonstrated in the adults with Down's syndrome. The results were within the normal range, and there was no difference between those with Down's syndrome and the other mentally retarded patients. Human growth hormone (HGH) and body height were studied in a previous work. Some correlations with these data are, nevertheless, included herein because they are of relevance. SmC correlated with body height in Down's syndrome, while there was no correlation between SmC and HGH or between HGH and body height.