Mutations in the hepatocyte nuclear factor-1alpha gene in MODY and early-onset NIDDM: evidence for a mutational hotspot in exon 4

We have recently shown that mutations in the gene encoding the transcription factor hepatocyte nuclear factor (HNF)-1alpha are the cause of one form of maturity-onset diabetes of the young (MODY3). Here, we report the exon-intron organization and partial sequence of the human HNF-1alpha gene. In addition, we have screened the ten exons and flanking introns of this gene for mutations in a group of 25 unrelated white subjects from Germany who presented with NIDDM before 35 years of age and had a first-degree relative with NIDDM. Mutations were identified in nine of these individuals, suggesting that mutations in the HNF-1alpha gene are a common cause of diabetes in German subjects with early-onset NIDDM and a family history of diabetes. Thus, screening for mutations in this gene may be indicated in subjects with early-onset NIDDM. Interestingly, three of the nine mutations occurred at the same site in exon 4 with insertion of a C in a polyC tract, centered around codon 290 (designated Pro291fsinsC), thereby resulting in a frameshift during translation and premature termination. Analyses of linked DNA polymorphisms in the HNF-1alpha gene indicated that the Pro291fsinsC mutation was present on a different haplotype in each subject, implying that the polyC tract represents a mutational hot spot. We have also identified the mutation in the HNF-1alpha gene in the Jutland pedigree, one of the original MODY pedigrees reported in the literature, as being a T-->G substitution in codon 241, resulting in the replacement of a conserved Cys by Gly (C241G). The information on the sequence of the HNF-1alpha gene and its promoter region will facilitate the search for mutations in other subjects and studies of the role of the gene in determining normal beta-cell functions.

[Differential therapy with oral antidiabetic drugs]

The more than 3 million type II diabetics in Germany constitute a true therapeutic challenge. Type II diabetes mellitus is part of the so-called metabolic syndrome characterized by the problem of insulin resistance/hyperinsulinemia. Treatment of type II diabetes aims at reducing insulin resistance. Oral antidiabetic management must be based on diabetic diet, in conjunction--if needed--with monotherapy with acarbose or metformin. Only after exhausting these principles of management, acarbose or metformin may be combined with sulfonylurea. Primary monotherapy with insulinotropically acting sulfonylureas is, in most cases, no longer appropriate as we are learning more about the pathophysiology of metabolic syndrome.

Secretion of antileucoprotease from a human lung tumor cell line

Two human tumor cell lines were analyzed for the production of human antileucoprotease (ALP). One of them, a human squamous lung carcinoma cell line (HS-24) synthesized, as confirmed by Western blot analysis, high amounts of ALP in serum-free medium. The supernatant inhibited elastase, chymotrypsin and trypsin. Northern blot analysis with an 18-mer radiolabelled oligonucleotide, derived from an ALP specific cDNA clone, revealed a specific mRNA of about 700-800 nucleotides in HS-24 tumor cells. In contrast, a secondary human lung tumor cell line (SB-3), derived from the adrenal cortex, did not synthesize ALP when assayed under identical conditions. The supernatant inhibited only trypsin and chymotrypsin.

[Long-term therapy with human insulin. Clinical experiences]

During in-patient admission after metabolic stabilisation insulin treatment of 32 type-1-diabetics was changed from bovine insulin (Depot-Insulin Hoechst CR) to semisynthetic human insulin of the intermediary type (Depot-H-Insulin Hoechst). Out-patient follow-up over a period of 12 months showed constant satisfactory mean day blood sugar values and morning postprandial blood sugar. 14 patients, however, showed significantly increased fasting blood sugar values which could be adjusted after change of evening insulin injections to the longer acting NPH insulin without normal insulin admixture (Basal-H-insulin Hoechst). In addition, a slight but not significant reduction of daily insulin requirements could be noted. There was no change of the relation between morning and evening insulin dosage. Hypoglycaemias did not occur significantly more frequently and hypoglycaemic symptoms showed no alterations.

[Combination therapy with insulin and sulfonylurea in secondary failure of sulfonylurea therapy]

Among 16 type II diabetics who were secondary failures on sulphonylurea treatment alone, eight (group A) were changed to a combined regimen of insulin and sulphonylurea (glibenclamide), the other eight (group B) received insulin alone. Patients in group A were on the combined schedule for ten days, followed by ten days of insulin alone, followed by six months of combined treatment. In the first ten days those on combined treatment in group A required on average 30% less insulin that those of group B, with a comparable metabolic state, while insulin requirements significantly rose after ten days on insulin alone. After renewed combined treatment the insulin dose could once again be reduced, but after eight weeks there was a rise in the insulin requirement, as for group B patients. During the further observation period of three months there were no significant differences in the insulin requirement between the two groups. Combination treatment with sulphonylurea and insulin in secondary failures thus, in the short term, reduces insulin requirement; but in the long term it is not significantly different from insulin treatment alone.

[Des-phe-insulin-containing intermediary insulin compared with usual commercial preparations (author's transl)]

In 20 type I diabetics comparison were made between Optisulin -depot CS (25% dissolved porcine Des-Phe-insulin/insulin and 75% crystalline porcine insulin), an intermediary insulin without depot additives, and two depot-additive containing insulins (Depot Insulin Hoechst CS and insulin Leo Mixtard) during a period of hospitalization. Des-Phe-insulins are insulins in which phenylalanine has been split off from the B chain of insulin. Since mixtures of Des-Phe-insulins with crystalline insulins are stable, there is the possibility of manufacturing monospecies-intermediary insulins without depot additives. Continued surveillance of blood sugar during application of Optisulin depot CS showed good control of the diabetic metabolism when compared with the commercially available insulins. Optisulin depot CS in its action is comparable to the two commercially available depot insulins. Side effects and allergic skin changes did not occur. Thus Optisulin depot SC adds to the at present available range of Des-Phe-insulin-containing insulins.

[Are des-Phe-insulin-containing insulin combinations preferable to regular trade preparations?]

Des-phe-insulins are modified insulins in which phenylalanin is eliminated from the b-chain of the normal insulin. Preparations containing des-phe-insulin and cristalline insulin have a good stability and one can produce insulins with different profiles. 50 diabetics were treated with different des-phe-insulin containing preparations. The carbohydrate metabolism was well controlled during the application of the new preparations. There were no side effects nor skin allergies. Des-phe-insulin containing insulins present a new interesting aspect in the treatment of insulin dependent diabetes mellitus.