A transition of G to A at nucleotide position 279 in exon 1 ofthe vasopressin gene has been identified in patients with familial central diabetes insipidus. The mutation predicts an amino acid substitution of Thr (ACG) for Ala (GCG) at the COOH terminus of the signal peptide in preprovasopressin (preproVP). Translation in vitro of wild-type and mutant mRNAs produced 19-kD preproVPs. When translated in the presence of canine pancreatic rough microsomes, wild-type preproVP was converted to a 21-kD protein, whereas the mutant mRNA produced proteins of 21 kD and 23 kD. NH2-terminal amino acid sequence analysis revealed that the 21-kD proteins from the wild-type and the mutant were proVPs generated by the proteolytic cleavage of the 19-residue signal peptide and the addition of carbohydrate. Accordingly, mutant preproVP was cleaved at the correct site after Thr-19, but the efficiency of cleavage by signal peptidase was < 25% that observed for the wild-type preproVP, resulting in the formation of a predominant glycosylated but uncleaved 23-kD product. These data suggest that inefficient processing of preproVP produced by the mutant allele is possibly involved in the pathogenesis of diabetes insipidus in the affected individuals. (J. Clin. Invest. 1993. 91:2565-2571

The efficacy of a noninvasive hemoglobin monitoring device (Astrin, Sysmex, Kobe, Japan) was evaluated for healthy volunteers and for patients with hematologic disorders. At the same time, the effects of WBC counts on noninvasive monitoring were studied by clinical evaluation and in ex vivo experiments. The hemoglobin levels determined by the device (Ast-Hb) and a conventional analyzer (T-Hb) were compared. The coefficient of correlation between findings with the Ast-Hb and the T-Hb for healthy volunteers was r = 0.626, whereas that for patients with hematologic disorders was r = 0.762. A comparison of the ratios of measurement errors in hemoglobin levels by Ast-Hb and T-Hb indicated that the number of WBCs had no effect on hemoglobin monitoring. Moreover, ex vivo studies using isolated WBCs and an optical model that imitates blood vessels and tissue in human fingers confirmed these results. Therefore, this new hemoglobin monitoring device can be expected to be useful for continuous hemoglobin monitoring.

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Dermatomyositis (DM)has not yet been reported as a complication of myelodysplastic syndrome (MDS). A 50-year-old man was diagnosed as having MDS because of the presence of anemia, the appearance of immature cells in peripheral blood, and the abnormal cellular morphology. A few months later, high fever, myalgia and erythema developed. Although DM symptoms were resistant to high-dose corticosteroid administration, methotrexate (MTX) therapy improved not only the symptoms of DM but also hematologic findings related to MDS. This indicates that immunosuppressive therapy including MTX administration can be useful for patients with MDS with autoimmune symptoms. Am.

A 61-year-old woman, who was diagnosed in 1982 as having polycythemia vera, was admitted to our hospital in July 1998 because of a splenic tumor in an enlarged spleen due to myelofibrosis. As it was difficult to identify the etiology of the splenic tumor, partial splenectomy was carried out. The resected tumor proved to be an extremely proliferative lesion as the result of extramedullary hematopoiesis. Since it is difficult to diagnose the etiology of splenic tumor, the collection and analysis of reports of relevant cases may well facilitate diagnosis. (Internal Medicine 39: 416-418, 2000)