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Biomedical subjects

N Kasai

Publications and source records attributed to N Kasai.

At least 109 records · Page 6Linked to original sources
PubMed1991

Occurrence of autoimmune antibodies to liver microsomal proteins in association with fulminant hepatitis in the LEC strain of rats.

The Long Evans Cinnamon (LEC) rat, which has been established as a strain showing hereditary hepatitis and hepatic carcinoma, was found to possess autoimmune antibodies to liver microsomal proteins, particularly to a protein with the molecular weight of 56kD. The antibodies also recognized a protein(s) in liver microsomes from Long Evans Agouti and Sprague-Dawley rats. About 42 and 15 percent of respective female and male LEC rats died within a week after acute hepatitis; sera from all of the animals contained the antibodies. About 43 and 0 percent of the surviving female and male LEC rats possessed the antibodies, respectively. These results suggest that the autoantibodies occur in association with acute lethal hepatitis in the LEC rats.

Animals↗
PubMed1991

Preliminary crystallographic study of a pseudoazurin from methylotrophic bacterium, Methylobacterium extorquens AM1.

Single crystals of pseudoazurin, one of the blue copper proteins produced by methylotrophic bacterium Methylobacterium extorquens AM1, have been obtained by the method of vapor diffusion with ammonium sulfate as a precipitant at pH 8.0. Crystals belong to the orthorhombic system, space group P2(1)2(1)2(1), with unit cell dimensions of a = 52.619(4) A, b = 63.280(6) A, c = 35.133(4) A. The asymmetric unit includes one molecule of pseudoazurin (Vm = 2.18 A3/dalton). The crystals are so stable against X-ray irradiation that diffraction intensities of the native crystal up to 1.68 A resolution could be collected from only one crystal. Among the many heavy-metal reagents examined, uranyl acetate gave an effective isomorphous derivative.

Azurin↗
PubMed1991

Crystallization and main-chain structure of neutral protease from Streptomyces caespitosus.

A neutral protease, i.e., a zinc-containing metalloendoprotease from Streptomyces caespitosus, has been crystallized using acetone as a precipitating agent. The crystals diffract to better than 1.5 A resolution when a rotating anode X-ray generator is used as an X-ray source. Protein phase angles were calculated by the multiple isomorphous replacement method using two heavy-atom derivatives (HgCl2 and CH3HgCl). A 6 A resolution electron density map clearly showed molecular boundaries. Although its amino acid sequence is not known, the folding pattern of the polypeptide chain could be traced on a 2.5 A resolution electron density map. A large cleft, which is located on the molecular surface, was proved to be the active site of the enzyme by structure analyses of inhibitor-complex crystals. The highest electron density peak, which corresponds to the cleft, was assigned to a catalytically essential zinc atom on difference Fourier synthesis between native and EDTA-soaked crystals.

Binding Sites↗
PubMed1991

Crystallization and preliminary X-ray diffraction studies of a flavoprotein, FP390, from a luminescent bacterium, Photobacterium phosphoreum.

A flavoprotein, FP390, obtained from a luminescent bacterium, Photobacterium phosphoreum, in the purification of luciferase has been crystallized by the vapor-diffusion procedure. Crystals obtained from polyethylene glycol 4000 solutions, whose X-ray photographs show powder diffraction patterns, were unsuitable for further crystallographic work. However, tetragonal crystals grown from potassium phosphate solution well diffracted X-rays beyond 3 A resolution. The space group of this crystal is P4(1)22 or P4(3)22 with unit-cell dimensions of a = b = 76.8 and c = 241 A. Assuming two or three molecules in an asymmetric unit, the value for the crystal volume per unit molecular mass, Vm, is calculated as 3.3 or 2.2 A3/Da, respectively. A total of 13,555 independent reflections for the native crystal was collected up to 3 A resolution using a Weissenberg camera attached to the synchrotron radiation source, the merging R factor being 0.077 for 79,335 measurements.

Bacterial Proteins↗
PubMed1991

Neutralization of Shwartzman-inducing activity by antibodies recognizing the Re core or lipid A structures of lipopolysaccharide from Salmonella minnesota R595 and Pseudomonas vesicularis JCM1477.

Antibodies recognizing the Re core or lipid A structures of lipopolysaccharide (LPS) derived from Salmonella minnesota R595 and Pseudomonas vesicularis JCM1477 were tested for the ability to neutralize the preparatory activity of endotoxin using the local Shwartzman reaction. Shwartzman-inducing activity of R595 LPS (Re-form) was strongly suppressed when the LPS was incubated with the rabbit anti-R595 antiserum or the purified IgG antibody which recognizes core region of the LPS. The antiserum also suppressed the preparatory activity of LPS from S. typhimurium SL1102 (Re) and Escherichia coli F515 (Re), but not that of either S. typhimurium LT-2 (S) LPS or R595 lipid A. Moreover, it was found that the murine monoclonal antibody (MAb), SmRe100G (IgG2a) which recognizes the core region of R595 LPS, significantly suppressed the preparatory activity of R595 LPS. Both conventional antibodies specific to R595 lipid A, which contains a 1,4'-bisphosphorylated beta-D-glucosaminyl-alpha-D-glucosamine disaccharide structure, and JCM1477 lipid A, which contains a monophosphorylated 3-amino-D-glucosamine disaccharide structure, neutralized the preparatory activity of homologous and a closely related lipid A, but not that of LPS. In addition, it was observed that MAb Sm5G (IgG2b) specific to enterobacterial lipid A preparations (especially R595 lipid A) neutralized the preparatory activity of R595 lipid A, although the effect was somewhat weak as compared with that of rabbit antiserum. These results suggest that anti-Re LPS antibody binding to the core of Re LPS is involved in suppressing the endotoxic activity of Re LPS, and that the direct binding of anti-lipid A antibody to some specific epitopes of lipid A is important in neutralizing the endotoxic activity.

Animals↗
PubMed1991

[Morphobiology and pathogenicity of Eimeria falciformis var. pragensis Cerna, Seraud, Mehlhorn & Scholtyseck, 1974 in mouse (Mus musculus)].

The life cycle of a species of murine Eimeria, isolated from a commercial source of mice is described using experimental infections. A pure strain was established starting from a single oocyst administered to Eimeria-free Swiss white mice. The prepatent period was 6 1/2 to 7 days, and the patent period lasted 6 to 10 days. Oocysts were subspherical or ovoid, with a smooth double-layered colourless membrane. Micropila was absent. The sporulated oocysts measured 15.7-25.1 x 14.1-22.0 microns (X780 = 21.3 x 16.9 microns). One to 4 polar granules were present. The oocyst residuum was absent. Sporocysts were ellipsoid, measured 11.5 x 6.3 microns (n = 780), with Stieda body and a compact subspherical sporocyst residuum. The sporozoites were elongated, 17.7 x 3.2 microns (n = 100), partially curled around each other. The endogenous stages were found only in the large intestine, with at least 4 generations of schizonts. Mature 1st generation schizonts, first seen 24 hr post-infection (HPI) measured 10.3 x 10.6 microns and had 8 to 25 merozoites 5.0-10.0 x 1.0-3.0 microns. Mature 2nd generation schizonts were first seen 48 HPI, measured 14.4 x 8.1 microns and had 8 to 20 merozoites 11.0-16.0 x 2.0-3.0 microns. Two forms of presumably 3rd generation schizonts appeared between 72 and 96 HPI: one measuring 13.9 x 8.5 microns, containing large merozoites (17.0-19.0 x 2.0-4.0 microns) and the other measuring 7.3 x 10.4 microns, where 6 to 10 merozoites (8.0-13.0 x 1.0-3.0 microns) were found. Fourth generation schizonts measuring 10.4 x 11.9 microns, with 26 a 48 or more merozoites (8.0-13.0 x 2.0-3.0 microns) were first seen at 132 HPI. Mature macro and microgamonts were first observed at 144 HPI. The sporulation of 72.0% of the oocysts in 2.0% (w/v) potassium dichromate at 23-24 degrees C occurred in 9 days. Usually the infected mice showed depression, anorexia, weight loss, diarrhea or dysentery, and dehydration. The clinical picture w as more pronounced at 6 to 10 days post-infection (DPI). Mortality was highest between the 8th and 13th DPI, with a peak at 9 DPI in groups which received 1.1 x 10(4) to 4.4 x 10(4) oocysts. Groups infected with 5.5 x 10(3), 8.8 x 10(4) or 1.76 x 10(5) oocysts showed different results. Epithelial destruction, edema, inflammation, necrotizing enteritis followed by glandular regeneration and realing were observed restricted to the large intestine. The isolated Eimeria was named E. falciformis var. pragensis based on its morphobiological characteristics.

Animals↗
PubMed1990

Magnetic detection of sleep spindles in normal subjects.

The magnetoencephalogram (MEG) and electroencephalogram (EEG) were recorded simultaneously from 3 normal subjects during light sleep. The extracranial magnetic field patterns associated with the ionic currents within the brain (MEG) were measured using a SQUID magnetometer in a magnetically shielded room. Although a previous report indicated that there are few sleep spindles in MEG records, we observed many in all 3 subjects. We believe this is because measurements were made vertically at the vertex region.

Adult↗
PubMed1990

Crystallization and preliminary X-ray diffraction studies of C-phycocyanin from a red alga, Porphyra tenera.

C-Phycocyanin from a red alga, Porphyra tenera, has been crystallized by the vapor-diffusion procedure. Both orthorhombic and hexagonal forms were obtained from ammonium sulfate solutions, whereas only the orthohombic form was selectively grown from sodium citrate solutions. The orthorhombic crystals are more suitable for further crystallographic work; their space group is P2(1)2(1)2(1), with unit-cell dimensions of a = 105, b = 121, and c = 184 A. The asymmetric unit comprises two (alpha beta)3 trimer molecules of C-phycocyanin. These crystals diffract X-rays up to about 3 A resolution.

Diffusion↗
PubMed1990

Tumor necrosis factor changes sensitivity of differentiation of mouse leukemia M1 cells by lipopolysaccharide.

A clone of mouse leukemia M1 cells was induced to differentiate by lipopolysaccharide (LPS) (LPS-sensitive clone) while another clone of the same cells was resistant (LPS-resistant clone). LPS and lipid A preparations from Pseudomonas diminuta and Pseudomonas vesicularis were as active as Escherichia coli LPS in the induction of differentiation of the LPS-sensitive clone. Synthetic lipid A precursor Ia (compound 406), which has no interleukin 1 (IL-1)-inducing activity toward monocytes, had strong differentiation-inducing activity toward the LPS-sensitive clone. The combined treatment of the LPS-sensitive clone with LPS and recombinant tumor necrosis factor (rTNF) did not further increase the degree of differentiation induced by LPS alone. By contrast, the LPS-resistant clone was markedly induced to differentiate by LPS in the presence of rTNF. Combined treatment of the LPS-resistant clone with LPS and other cytokines such as recombinant IL-1 alpha, recombinant granulocyte colony-stimulating factor, and interferon-gamma was not effective in inducing marked synergistic differentiation. These results raise the possibility that rTNF changes the sensitivity of M1 cells to induction of differentiation by LPS.

Animals↗
PubMed1990

Interconversion of aflatoxin B1 and aflatoxicol by several fungi.

Four fungal strains, namely, Aspergillus niger, Eurotium herbariorum, a Rhizopus sp., and non-aflatoxin (AF)-producing Aspergillus flavus, which could convert AF-B1 to aflatoxicol (AFL), could also reconvert AFL to AF-B1. The interconversion of AF-B1 to AFL and of AFL to AF-B1 was ascertained to occur during proliferation of the fungi. These reactions were distinctly observed in cell-free systems obtained from disrupted mycelia of A. flavus and the Rhizopus sp., but they were not observed in culture filtrates from intact (nondisrupted) mycelia of the same strains. The interconversion activities of AF-B1 and AFL were not observed when the cell-free systems were preheated at 100 degrees C. These findings strongly suggest that the interconversion of AF-B1 and AFL is mediated by intracellular enzymes of A. flavus and the Rhizopus sp. In addition, the isomerization of AFL-A to AFL-B observed in culture medium was also found to occur by the lowering of the culture pH.

Aflatoxin B1↗
PubMed1990

[Heat and ozone resistance of Bacillus spores isolated from laboratory animals].

Heat resistance of free-spores of 78 Bacillus strains isolated from laboratory animals was examined. Spores of 41 out of 78 strains survived for 320 minutes at 70 degrees C, 27 for 160 min, at 100 degrees C, only one for 20 min. at 110 degrees C by autoclaving, and none for 5 min. at 120 degrees C. D-values at 100 degrees C of 9 strains determined were between 5.03 and 30.06 min. Spores of 9 strains from stock cultures were exposed to ozone gas at various conditions. Ozone resistance of spores was closely dependent upon relative humidity. D-values of the spores tested by treatment with 200 ppm ozone at 60% RH were over 200 min., especially over 1,000 min. in 4 strains, indicating that exposure to ozone at a moderate humidity for 6 hours could not sterilize Bacillus spores. At 90% RH, however, treatment with 200 ppm ozone for 6 hr. might be effective for a routine sterilization in laboratory animal facilities.

Animals↗
PubMed1990

Clinico-pathological studies of LEC rats with hereditary hepatitis and hepatoma in the acute phase of hepatitis.

The LEC rat, which suffers from hereditary hepatitis, was examined for elucidation of its clinicopathological characteristics during development of the acute phase of hepatitis by quantitative analyses of histological observations of the liver in combination with laboratory data on various serum enzymes. The progression of acute hepatitis in the LEC rat was observed to begin insidiously early in life, i.e., a few enlarged hepatocytes and Councilman bodies appeared at around 8 weeks of age without clinical signs. Furthermore, it was revealed that the acute phase of hepatitis started with a remarkable increase of Councilman bodies, large nuclei and hepatocytes in mitosis in the liver 3 to 4 weeks before the onset of fulminant hepatitis, which is characterized by the elevation of serum enzyme activities such as GOT, GPT and gamma-GTP, and the onset of jaundice. From those observations, three stages were proposed for the progression of acute hepatitis in the LEC rat.

Acute Disease↗
PubMed1990

Psammoma bodies in metastatic carcinoma to the thyroid.

In a review of the 427 cases of thyroid with malignant neoplasm that were surgically resected at the Cancer Institute Hospital during the 10-yr period from 1978 to 1987, five cases of metastatic carcinoma to the thyroid were found. Psammoma bodies were histologically observed in three of the five cases. Primary thyroid carcinoma was highly suspected in the three cases, because psammoma bodies were detected during preoperative examinations that included image diagnosis and aspiration biopsy cytology. Thus, the presence of psammoma bodies in any kind of thyroid tumor should be carefully evaluated, both clinically and histologically, to ensure that the possibility of metastatic origin is not overlooked.

Adenocarcinoma↗
PubMed1989

First crystallization of a phosphoenolpyruvate carboxylase from Escherichia coli.

Two different forms of crystal for a phosphoenolpyruvate carboxylase from Escherichia coli were obtained by the hanging-drop vapor diffusion technique, using polyethylene glycol 4000 as precipitant. The hexagonal crystal in space group P6(2)22 (or P6(4)22) has cell dimensions of a = 131 A and c = 325 A, whereas the orthorhombic crystal in space group I222 has a = 119 A, b = 252 A and c = 83 A. A tetrameric molecule (396,244 Mr), a subunit of which contains 883 amino residues, has a crystallographic 2 symmetry in the hexagonal crystal or 222 symmetry in the orthorhombic crystal, respectively.

Carboxy-Lyases↗
PubMed1989

Isolation of 9-hydroxy-delta-tetradecalactone from lipid A of Pseudomonas diminuta and Pseudomonas vesicularis.

A lipid component was isolated from the fatty acid fraction of acid hydrolysates of lipid A derived from Pseudomonas diminuta JCM 2788 and Pseudomonas vesicularis JCM 1477 lipopolysaccharides. By structural analysis of the lipid and its trimethylsilyl and acetyl derivatives by thin-layer chromatography, gas chromatography-mass spectrometry, mass spectrometry, infrared spectrometry and 13C-NMR, it was identified as 9-hydroxy-delta-tetradecalactone.

Lactones↗
PubMed1989

Epitope analysis of lipid A preparations from Pseudomonas diminuta and Pseudomonas vesicularis.

In vitro antigenic reactivity of lipid A from Pseudomonas diminuta and Pseudomonas vesicularis with homologous and heterologous lipid A antibodies including monoclonal antibodies was studied by inhibition test of enzyme-linked immunosorbent assay (ELISA). The results suggest that both Pseudomonas lipid As have very similar epitopes, including species-specific and cross-reactive epitopes as compared with enterobacterial lipid A.

Cross Reactions↗