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Biomedical subjects

H Mehnert

Publications and source records attributed to H Mehnert.

At least 19 recordsLinked to original sources
PubMed1992

What is the clinical significance of insulin resistance?

Insulin resistance is a frequent phenomenon and a marker of increased risk for non-insulin-dependent diabetes mellitus (NIDDM) and atherosclerosis. According to recent estimations, not only individuals with obesity, NIDDM, and impaired glucose tolerance (IGT) but also one fourth of the "healthy" glucose tolerant and the majority of the hypertensive population are insulin resistant. Insulin resistance describes a tissue- and pathway-specific defect of glucose metabolism that is compensated for by hyperinsulinemia, leading to a cluster of undesirable hypertensiogenic, diabetogenic, and atherogenic processes. The initial defect can be directly measured by glucose clamp and other sophisticated techniques; the clinical syndrome may be derived from a network of related variables known to be associated with reduced insulin action. Because neither clamps nor serum insulin screenings will be available on a widespread basis, early diagnosis based on clinical criteria is crucial. A new interpretation of the "thrifty" genotype hypothesis may explain why insulin resistance, which formerly apparently represented an advantage in the evolutionary selection process, is such a frequent phenomenon. Improvement of impaired insulin action as a therapeutic principle may play a future central role in an integrated lifestyle approach of primary prevention of noncommunicable diseases such as NIDDM, hypertension, and atherosclerosis.

Coronary Disease↗
PubMed1991

HLA-associated insulin autoantibody formation in newly diagnosed type I diabetic patients.

To assess a possible HLA association with anti-insulin autoantibodies (IAAs) in human insulin-dependent (type I) diabetes, 51 newly diagnosed type I diabetic patients (mean age 22 +/- 8 yr) were typed for HLA-DR and HLA-DQ and studied for IAAs before exogenous insulin therapy with a competitive radioimmunoassay (normal range less than or equal to 49 nU/ml). The level of IAAs in 16 patients exceeded our upper limit of normal, and 18 had high-titer islet cell antibodies (ICAs; greater than or equal to 40 Juvenile Diabetes Foundation U). A striking association with HLA-DR4 (DQw3) in both the prevalence and the level of IAAs was found (IAA positivity in patients with DR4/4 vs. DR4 heterozygous vs. non-DR4: 90 vs. 29%, corrected [c] P less than 0.01, vs. 5%, Pc less than 0.0001; IAA positivity in patients with DR4 vs. non-DR4: 50 vs. 5%, Pc less than 0.005; IAA level in patients with DR4/4 vs. DR4 heterozygous vs. non-DR4: 111 vs. 17 nU/ml, Pc less than 0.01, vs. 20 nU/ml, Pc less than 0.0001; IAA level in patients with DR4 vs. non-DR4: 45 vs. 20 nU/ml, Pc less than 0.01). In contrast, none of the DR3+ subjects had IAAs above normal range, except in conjunction with DR4 (DR3 vs. non-DR3: 12 vs. 42%, Pc less than 0.05). However, there was no significant relationship between DR3 and IAAs after correcting for the number of DR4 alleles. No relationship was seen between age of onset, IAA level, and HLA typing in our population, and no relationship was found between ICA positivity and HLA antigens.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Incidence and symptomatology of lung embolism in relation to the site of deep venous thrombosis].

The uncertainty about the true incidence of pulmonary embolism (PE) in connection with deep venous thrombosis (DVT) becomes evident when comparing the results of autopsy--vs. clinical studies, with the former showing a three-fold elevated rate of embolisation. In order to evaluate the percentage of clinically inapparent PE, all patients (65 females, 54 males, mean age 61.3 years) hospitalized between April 1989 and March 1990 with suspected DVT and/or PE underwent duplex-sonography and pulmonary scintigraphy. In 108 cases, DVT could be ascertained, whereas 11 patients only suffered from PE. In 57.4% of all DVT, PE was diagnosed. Of the 73 cases with PE, only 53.4% of the patient stated typical symptoms primarily. In more than 1/4 of the patients with primary symptoms of PE, no DVT could be diagnosed. There was no significant difference between the occurrence of PE in relation to the localisation of DVT, with 1/3 to 1/2 being asymptomatic. 1/4 of the patients with leg-thrombosis and 1/7 with thrombosis of the iliac vein did not complain of typical symptoms of thrombosis. Furthermore, an increased PE-rate seems to occur with an elevated ultrasound echogenity of the thrombus. As a result of the study pulmonary szintigrams seem to be indicated in all cases of DVT in order to evaluate the total PE risk.

Adult↗
PubMed1990

[Results of local thrombolysis with special reference to diabetic metabolism].

The influence of diabetes on the primary and long-term success rate after 145 local thrombolyses in peripheral arterial disease stages III and IV was evaluated. 75 patients suffered from thrombotic, 62 patients from embolic occlusions, with eight patients suffering from thrombangitis obliterans. Regarding the localisation of vascular occlusion 0.6% suffered under an occlusion of the iliacal artery, 21% of the femoral artery, 16% of the popliteal artery, 7% of the vessel of the lower limb and 55.4% showed a combined occlusion of the femoral- and popliteal artery and the artery of the lower limb. In cases of embolic occlusions only marginal differences could be observed, while the primary success-rate of thrombotic occlusions showed greater differences between both groups (75% vs. 91%). During the follow-up, no differences between both groups could be established (patency-rate of 79% for both groups). The same applies to the prognostic factors: peripheral run off, length, duration of occlusion and the clinical stage (Fontaine IIb to IV). The remarkable differences between diabetic and non-diabetic patients in cases of occlusions of more than 16 cm (66% vs. 88% in primary and 55% vs. 77% in long-term success) can be explained by the high percentage of diabetic patients with poor run-off and microangiopathy. Regarding the above parameters, primary and long-term results seemed to be less in diabetic patients, even though a long-term patency could be observed in 2/3 of diabetic patients in stages IIb and IV with primary success.

Adult↗
PubMed1990

[Effect of prostaglandin E1 on amino acid metabolism of human skeletal muscle].

The influence of an intraarterial infusion of PGE1 on the amino acid metabolism of human skeletal muscle was examined in healthy volunteers using the forearm technique. A continuous increase of perfusion from 2.9 +/- 0.1 ml/100 g x min to 5.4 +/- 1.5 after 60 min could be observed. Muscular amino acid balances were not changed after 30 min but significantly after 60 min of PGE1 infusion. Muscular release of most of the amino acids was reduced or shifted to an uptake. The accumulated balance of the amino acids showed a significant increase from -21.9 to +33.2 nmol/100 g x min after 60 min. Thus the infusion of PGE1 led to an inhibition of muscular proteolysis and/or to a stimulation of proteosynthesis. In view of the fact that kinines are released during exercise and are partially effective via prostaglandine liberation, the protein-anabolic effect of exercise might be explained by action of prostaglandins.

Adult↗
PubMed1990

[Essential hypertension and diabetes mellitus].

While the incidence of essential hypertension is not increased in type 1 diabetics, it is about three times as high in type 2 diabetics. Since in 50% of the cases, hypertension is present before the metabolic disorder becomes manifest, an association between the etiologies of the two disturbances was suspected as long as 65 years ago. A new understanding of the significance of insulin resistance and hyperinsulinemia suggests that the two conditions are part of a single metabolic disorder. This is supported by the fact that normal-weight hypertensives can also manifest insulin resistance, and they more often develop a type 2 diabetes mellitus. These facts urge us to re-think our therapeutic approach to hypertension, and to employ, as far as possible, only those substances that have no negative influence on the incidence of the metabolic disorder. With the introduction of ACE-inhibitors capable of improving insulin sensitivity, we now have, for the first time, the possibility of improving the prognosis of the metabolic syndrome. Moreover, their molecular mechanism of action provides initial clues as to the possible etiology of the syndrome.

Diabetes Mellitus, Type 1↗
PubMed1990

[ACE-inhibitors and glucose metabolism].

ACE-inhibitors exhibit their blood pressure-lowering activity not only via a reduction of angiotensin II but also via on increase of kinin levels. The latter are known to improve insulin action and hence carbohydrate metabolism in normal volunteers and diabetics. Accordingly, ACE-inhibitors display the same effects. As clinical trials show they are especially useful for the treatment of hypertension in diabetes mellitus.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1990

Risk of progression to diabetes of low titer ICA-positive first-degree relatives of type I diabetics in southern Germany.

In a prospective study to evaluate the prevalence and predictive potential of circulating cytoplasmatic islet cell antibodies (ICA) and competitive insulin autoantibodies (CIAA), we screened 406 non-diabetic first-degree relatives of patients with Type I diabetes mellitus (n = 154 for CIAA). The prevalence of ICA was 2.5% (10/406) and of CIAA 0.6% (1/154) in ICA- and 10% (1/10) in ICA+ relatives at initial screening. The titer of ICA positivity in all relatives varied between 1:1 and 1:4. Values of elevated CIAA were 256 nU/ml of the CIAA+/ICA+, and 97 nU/ml of the CIAA+/ICA- relatives (normal range less than or equal to 39 nU/ml). Sera for repeat ICA and CIAA determination was obtained, and 70% of relatives were found to be again ICA+ after 1.5 years, 40% after 3 years, and 10% after 5.7 years. Both CIAA+ relatives were found to be again CIAA+ on follow-up. Intravenous glucose tolerance tests (IVGTT) were performed in all antibody-positive relatives. No decrease in first-phase insulin secretion (1 + 3 min) below the 1st percentile was observed in any of the ICA+ relatives during follow-up. No ICA+, but one CIAA+/ICA- relative had developed Type I diabetes after 5.6 years of follow-up. In summary, these results indicate that low titer ICA (less than 40 JDF units) are often transient and relatives with low titer ICA rarely progress to Type I diabetes. Elevated CIAA appear to be constant over time and associated with increased progression to overt diabetes.

Adolescent↗
PubMed1990

Effects of beta-blocking agents on insulin secretion and glucose disposal.

Non-selective and to a lesser extent selective beta-blockers are known to slightly deteriorate glucose metabolism. This may be of clinical relevance, since patients with essential hypertension suffer from reduced insulin-sensitivity and some studies showed an increased incidence of diabetes type II with beta-blocker-treated hypertensive patients. However, it is not clear whether this effect is due to hypertension per se or in addition by antihypertensive treatment. The possible mechanisms by which beta-blockers influence carbohydrate metabolism are discussed. Insulin secretion is inhibited by beta-blockers in vitro. However, no effect is seen in vivo in man. Hepatic glucose production in theory may be influenced, but no effect is demonstrable. Muscular glucose uptake could be reduced; some data exist showing reduced peripheral insulin sensitivity, although there are controversial results. In conclusion, a deterioration of carbohydrate metabolism by beta-blockers is established, the mechanism whereby remains obscure.

Adrenergic beta-Antagonists↗