Effects of various compounds on histidine decarboxylase activity: Active site mapping

The effect of about one hundred compounds on the activity of histidine decarboxylase partially purified from whole bodies of fetal rats was determined. Most of them at their 10 mM concentration had little effect on the enzyme activity; but 12 compounds inhibited the enzyme to a greater extent than 30%. Among these, except for -methylhistidine that has been known to be a strong and specific inhibitor, DOPA, homocysteine, cysteine, methionine and urocanic acid were the best inhibitors; -phenyllactic acid, phenylpyruvic acid and carnosine were less strong inhibitors; valine, oxaloacetic acid andN -methylimidazole acetic acid were weak inhibitors. Histamine had no inhibitory action. Thus, the substrate binding site of histidine decarboxylase is very rigid and specific forl-histidine.     

A peculiar immunoglobulin M (IgM) identified in eggs of chum salmon (Oncorhynchus keta).

A protein reacting with antibody against chum salmon serum IgM was found in salmon egg yolk. The protein tentatively named IgM-like protein was partially purified from egg yolk extract by removal of euglobulin from the extract by dialysis against a low ionic strength buffer following DEAE ion-exchange chromatography. The IgM-like protein was antigenically identical with serum IgM, showing a complete fusion of precipitin line of the IgM-like protein with that of serum IgM on double immunodiffusion with antiserum IgM. The molecular weight of intact IgM-like protein was assessed by 3% SDS-PAGE to be 495 kDa, smaller than that of serum IgM (750 kDa). Upon 10% SDS-PAGE with mercaptane and subsequent Western blotting with antiserum IgM, the IgM-like protein separated into three components with molecular weights of 68 kDa, 51.5 kDa, and 23 kDa. The 68 kDa, the most minor component, and the 23 kDa, the smallest molecular weight component, were identified, respectively, as H and L chain in view of their molecular weights identical to those of serum IgM. The 51.5 kDa, the main component, was also identified as H chain, since it reacted with antiserum IgM absorbed with purified L chain. From these results, it was concluded that the IgM-like protein in egg yolk, having a lower molecular weight than that of serum IgM, consists of H chain of smaller molecular weight as well as H and L chain of ordinary molecular weight.     

Hepatoblastoma in an 82-year-old man. An autopsy case report

An autopsy case of adult hepatoblastoma is presented. The patient was an 82-year-old male with chronic hepatitis of 7 years' duration. The liver tumor was detected 6 months before death. Autopsy revealed a large hepatic tumor occupying about 80% of the entire liver. Histologically, the tumor showed typical features of mixed epithelial- and mesenchymal-type hepatoblastoma. The epithelial component consisted of fetal and embryonal cell types. The mesenchymal component showed primitive spindle-shaped cells with various degrees of cellularity. Chondroid areas and a few foci of osteoid formation were also present.     

Virus-associated hemophagocytic syndrome: the diagnostic usefulness of immature histiocytes with benign features in the bone marrow

A 2-year-old girl developed fever, hepatosplenomegaly, jaundice, lymphadenopathy and pancytopenia. Bone marrow examination revealed increased immature histiocytes (5.5%) and mature histiocytes with hemophagocytosis. All the abnormalities were normalized in one month without any chemotherapy. It was suggested that the presence of immature histiocytes with benign features, even if their number exceeds that of mature histiocytes, does not favor the diagnosis of malignant histiocytosis.     

Fine structure of hepatic sinusoids and their development in human embryos and fetuses

The fine structure of the hepatic sinusoids of 81 human embryos and fetuses and their development from 5 to 12 weeks gestation were studied. At 5 weeks gestation, sinusoid-like structures and Kupffer-like cells were observed between liver cell cords. Between 6 and 8 weeks gestation the sinusoids were completely developed. Definite Kupffer cells appear at this developmental stage, when the bone marrow has not yet formed. Floating macrophages form cell aggregates in the sinusoids which contact endothelial cells and settle as Kupffer cells. Erythroblastophagia is observed in Kupffer cells and macrophages. The endothelial linings are closed, with the attenuated cell processes and intercellular junctions between the adjoining endothelial cells. No transition was observed between Kupffer cells and endothelial cells. The findings suggest that Kupffer cells in the human embryo are extrahepatic in origin and that they reach the sinusoids via the circulatory system. Ito cells, which store fat, originate from mesenchymal cells in the septum transversum.     

Adrenomedullin and proadrenomudullin N-terminal 20 peptide (PAMP) are present in human colonic epithelia and exert an antimicrobial effect

The hypotensive and vasorelaxing peptides adrenomedullin (AM) and its gene-related peptide, proadrenomedullin N-terminal 20 peptide (PAMP), were found to be distributed on the surface of the colonic mucosa. AM and PAMP showed dose-dependent antimicrobial activity against E. coli. The results suggest that the novel vasoactive peptides AM and PAMP play an important role in mucosal defence.     

The Serum Factor from Patients with Ulcerative Colitis that Induces T Cell Proliferation in the Mouse Thymus Is Interleukin-7

The disturbance of immune regulatory T cells is related to the pathogenesis of ulcerative colitis. Here we demonstrated and characterized the serum factor from ulcerative colitis patients that induced proliferation of intrathymic T cells. The factor isolated from the patient sera by a combination of gel filtration and anion-exchange chromatography induced proliferation of CD4⁺CD8^– intrathymic T cells in the organ-cultured embryonic mouse thymus. Purification and amino acid sequence analysis of the serum factor demonstrated that the N-terminal 12 sequence was homologous to that of interleukin-7. SDS-PAGE and Western blot confirmed that purified serum factor was interleukin-7. Enzyme immunoassay demonstrated that the serum interleukin-7 concentration was significantly increased in the patients. PCR and Southern blot hybridization demonstrated that interleukin-7 mRNA expression was increased in the thymus tissues from patients but decreased in the colonic mucosa. Since interleukin-7 is a crucial cytokine for proliferation and differentiation of T cells in the thymus, the present study indicates that interleukin-7 may contribute to the disturbance of immune regulatory T cells in ulcerative colitis.