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Biomedical subjects

N Kasai

Publications and source records attributed to N Kasai.

At least 73 records · Page 4Linked to original sources
PubMed1995

Idiopathic membranoproliferative glomerulonephritis in Japanese children.

The course of idiopathic membranoproliferative glomerulonephritis (MPGN) in 41 Japanese children (21 boys, 20 girls) is reported. The mean follow-up period was 8 years, 9 months; 29 children with MPGN (71%) were identified by school urinary screening; 32 patients had type I MPGN, 2 type II and 7 type III; 10 patients were treated with multiple low-dose cocktail therapy (MLD), 8 with MLD followed by high-dose alternate-day (ALD) prednisolone and 21 with high-dose ALD prednisolone alone. In 1 patient, MPGN progressed to end-stage renal failure. The serum creatinine level in all of the remaining 40 patients was < or = 1.3 mg/dl at the last follow-up. Urinalysis was normal in 24 (59%). Of the 17 patients who still had urinary abnormalities, 4 had nephrotic syndrome. The incidence of remission of urinary abnormalities was highest in the patients treated with high-dose ALD prednisolone. Rebiopsy was performed in 33 patients, and revealed slight histological improvement in 11 (33%) patients, moderate improvement in 8 (24%), marked improvement in 5 (15%) and deterioration or no improvement in 9 patients (27%). Relatively few side effects of treatment were observed. The superior outcome of the MPGN patients in this compared with other studies may be the result of earlier detection and treatment.

Adolescent↗
PubMed1995

Studies on feeding of Argas (Persicargas) miniatus larvae (Acari: Argasidae) on naive chicks.

The histology of skin responses to infestation with Argas (Persicargas) miniatus Koch, 1844, larvae was investigated on previously unexposed 1-mo-old chicks. An amorphous, acidophilic substance, referred to as cement, was observed from 24 h after infestation until the ticks had detached. The morphology of the lesions changed gradually during the time of infestation. Initially, dissociation of collagen fibers and a mild infiltration with heterophil and mononuclear cells (12-24 h) was observed. Then, fibroblastic cords, mononuclear cell focuses, erythrocytes, and some heterophils (48-72 h) could be observed. Finally, predominance of fibroblast proliferation was noted.

Animals↗
PubMed1995

Assignment of the bacterial agent of urinary calculus in young rats by the comparative sequence analysis of the 16S rRNA genes of corynebacteria.

Comparative 16S rRNA gene sequencing was used to assign four isolates of spontaneous urinary calculus in young laboratory rats. The phylogenetic relationships among the rat isolates and selected species of corynebacteria were also inferred. Based on the homology and evolutionary distance analysis, the 16S rRNA genes of the rat isolates were almost identical with that of Corynebacterium renale ATCC 19412. Also the results of the phylogenetic analysis showed a close relationship among the isolates and C. renale, but they were clearly different from C. pilosum, C. cystitidis, C. kutscheri and Rhodococcus equi. The results of the present study and previously published biochemical data demonstrate that the organism involving urinary infections in young rats is identified to be C. renale.

Animals↗
PubMed1994

Evidence that alpha-fetoprotein suppresses the immunological function in transgenic mice.

We examined the in vivo immunosuppressive effect of alpha-fetoprotein (AFP) by infection experiments with Listeria monocytogenes, a facultative intracellular pathogen, using transgenic mice that express and produce human AFP. The transgenic mice showed diminished ability to eliminate bacteria in the early stage of infection. In addition, the transgenic mice had significantly reduced production of IFN-gamma in their livers and sera and TNF in their spleens. These data indicate that AFP suppresses the production of the cytokines, IFN-gamma and TNF in NK cells and macrophages so that the mice could not eliminate the bacteria. This is the first report that AFP has an in vivo immunosuppressive effect on cytokine production related to the early host defense against infection by microorganisms.

Animals↗
PubMed1994

Structural similarity of cytochrome c2 from Rhodopseudomonas viridis to mitochondrial cytochromes c revealed by its crystal structure at 2.7 A resolution.

The crystal structure of cytochrome c2 from Rhodopseudomonas viridis has been refined using molecular dynamics and restrained least-squares methods to a crystallographic R-factor of 0.216 at 2.7 A resolution. A structural comparison between Rps. viridis cytochrome c2 and the other bacterial cytochromes c2 or mitochondrial cytochromes c indicates that the overall protein foldings are very similar to each other with the exception of the surface loop and terminal region of the polypeptide chain. However, the position and hydrogen-bond pattern of the evolutionarily conserved water molecule buried within the heme binding pocket in Rps. viridis cytochrome c2 are common to those in the mitochondrial cytochromes c. This fact indicates that Rps. viridis cytochrome c2 is structurally more similar to mitochondrial cytochromes c than to the other bacterial cytochromes c2.

Crystallography, X-Ray↗
PubMed1994

Application of an automatic molecular-replacement procedure to crystal structure analysis of cytochrome c2 from Rhodopseudomonas viridis.

An automatic molecular-replacement procedure has been applied to solve the crystal structure of cytochrome c(2) from Rhodopseudomonas viridis. The structure was solved on the basis of the structure of tuna cytochrome c as a search model using an automatic processing program system, AUTOMR. The refinements by molecular dynamics and restrained least-squares methods result in a current crystallographic R factor of 0.219 for diffraction data at 3 A resolution.

Journal Article↗
PubMed1994

Refined crystal structure of pseudoazurin from Methylobacterium extorquens AM1 at 1.5 A resolution.

The crystal structure of pseudoazurin from Methylobacterium extorquens AM1 (PAZAM1) has been solved by the molecular replacement method using copper-copper distances as translation parameters, which were obtained from difference Patterson maps calculated with the synchrotron radiation data containing the multiwavelength anomalous-dispersion effect. The structure refinement was carried out by the use of molecular dynamics optimization and the restrained least-squares method. The final crystallographic R factor was 19.9% for the 14 365 reflections greater than 3sigma between 1.5 and 8.0 A resolution. This report describes the characteristic features of the structure of PAZAM 1 as well as the effectiveness of synchrotron radiation for structure analysis of metalloproteins. The environment of the metal active site and the structural differences among blue-copper proteins are discussed.

Journal Article↗
PubMed1994

Crystallization and preliminary X-ray diffraction studies of curculin. A new type of sweet protein having taste-modifying action.

A taste-modifying protein, curculin, has been crystallized by the vapor diffusion method using polyethylene glycol 400 as a precipitant. The crystals belong to orthorhombic space group P2(1)2(1)2(1) with unit cell dimensions: a = 105 A, b = 271 A, c = 48.7 A. The crystals diffract X-rays to at least a resolution of 3.0 A and are suitable for X-ray crystallographic studies.

Crystallization↗
PubMed1994

Increase of UDP-glucuronosyltransferase activities toward xenobiotics during the development of hereditary hepatitis in LEC rats.

UDP-glucuronosyltransferase activities were induced spontaneously during the development of hepatitis in LEC (Long Evans Cinnamon-like coat color) rats. Transition of hepatic microsomal UDP-glucuronosyltransferase activities was observed during the development of the LEC rat, which displayed spontaneous fulminant hepatitis with severe jaundice at about 12-16 weeks after birth. UDP-glucuronosyltransferase activities toward various substrates in 8-week-old LEC and LEA (Long Evans Agouti coat color; control) rats were similar. After 8 weeks of age, the transferase activities of LEA rats towards all substrates tested, except for bilirubin, decreased slightly during the next 24 weeks. In LEC rats, the transferase activities towards serotonin and several phenolic xenobiotics, such as 4-nitrophenol, 1-naphthol and 4-methylumbelliferone, but not 4-hydroxybiphenyl, increased about 2-fold at 16 weeks of age. During the 24 weeks following the first 8 weeks of age, the high level activities towards the xenobiotics continued, with the exception of bilirubin transferase activity which decreased gradually. These results suggest that a form of UDP-glucuronosyltransferase, which catalyzes the glucuronidations of serotonin and these xenobiotics except for 4-hydroxybiphenyl, is induced during the development of hepatitis in the LEC rat.

Animals↗
PubMed1994

A high frequency of induction of chromosome aberrations in the bone marrow cells of LEC strain rats by X-irradiation.

LEC strain rats, which have been known to develop hereditarily spontaneous fulminant hepatitis 4 to 5 months after birth, are highly sensitive to whole-body X-irradiation when compared to WKAH strain rats. The present results showed that the frequencies of all types of chromosome aberrations induced by X-irradiation in the bone marrow cells of LEC rats were approximately 2- to 3-fold higher than those of WKAH rats, though no significant difference was observed in the frequency of spontaneous chromosome aberrations between LEC and WKAH rats.

Animals↗
PubMed1994

Targeted pituitary tumorigenesis using the human thyrotropin beta-subunit chain promoter in transgenic mice.

We have generated transgenic mice that express the simian virus 40 (SV40) large T antigen under the control of a 1109 bp 5'-flanking sequence of the human thyrotropin beta-subunit (TSH beta) gene. The hybrid gene, termed TTP-1, was microinjected into fertilized mouse eggs and 11 transgenic mice were obtained. One of the transgenic mice, a female, a phenotypical dwarf, developed a pituitary tumor and wasted away from 7 to 9 weeks after birth. To establish the transgenic mouse line, her ovaries were transferred to a normal female, whose ovaries were removed beforehand. To examine the tissue specificity of transgene expression, mRNA of SV40 large T antigen was monitored in various tissues from the transgenic mice by the reverse transcriptase-polymerase chain reaction analysis, and was detected only in the pituitary. Histological and immunohistochemical analyses showed that the pituitary tumors of the transgenic mice were composed of poorly differentiated pituitary cells expressing SV40 large T antigen. These results indicated that the 1109 bp sequence of the human TSH beta 5'-flanking region is essential for pituitary-specific expression of SV40 large T antigen in transgenic mice, which exhibited a dwarf phenotype and developed pituitary tumors. The tumors were composed of undifferentiated cells and did not produce thyrotropin. These transgenic mice should provide a valuable animal model for studying the pathogenesis of anterior pituitary tumors.

Animals↗
PubMed1994

Radiation hypersensitivity of LEC strain rats controlled by a single autosomal recessive gene.

LEC strain rats (LEC rats), which are known to develop hereditarily spontaneous fulminant hepatitis 4-5 months after birth, were highly sensitive to whole-body X-irradiation when compared to WKAH strain rats. The radiosensitivity of F1 hybrids of LEC and WKAH rats was similar to that of WKAH rats and significantly lower than that of LEC rats. Segregation data of backcross hybrids (F1 x LEC and LEC x F1) suggested that the hypersensitivity of LEC rats to whole-body irradiation is controlled by a single autosomal recessive gene. The radiosensitivity of fibroblasts from LEC rats was higher than that of fibroblasts from WKAH rats. The repair process of DNA double-strand breaks in LEC cells was slower than that in WKAH cells. LEC rats could provide a useful animal model to assist in understanding the mechanism of radiation-induced DNA damage and repair.

Animals↗
PubMed1994

Spontaneous urinary calculus in young LEW rats caused by Corynebacterium renale.

Spontaneous urinary calculus was observed in only 27% of female LEW rats among nine inbred strains maintained in the Institute for Animal Experimentation. The condition occurred between 3 and 9 weeks of age with loss of weight, enlargement of the os urethral externum, anuria and general marasmus. All of the affected rats died from anuria 3 to 4 days after the onset. The affected rats had one to ten infected stones or many fine crystals of sand, which consisted of magnesium ammonium phosphate, in the urinary bladder and/or urethra. Analysis of microorganisms revealed that Corynebacterium renale, known as a causative agent of bovine pyelonephritis, was the most probable candidate for producing infection stones. This is the first report that the rat is spontaneously infected with C. renale. This could be a useful animal model for human urinary calculus and also for C. renale infection in the field of veterinary science.

Animals↗
PubMed1994

Structure of azurin from Achromobacter xylosoxidans NCIB11015 at 2.5 A resolution.

The crystal structure of azurin from a denitrifying bacterium, Achromobacter xylosoxidans NCIB11015, has been refined at 2.5 A resolution using diffraction data obtained by means of synchrotron radiation at KEK. Crystals suitable for X-ray experiment were obtained by the macro-seeding method and an intensity data were obtained on imaging plates mounted on a Weissenberg camera (Rmerge = 0.09). The initial model was obtained by the molecular replacement method using the structure of azurin from Alcaligenes denitrificans NCTC8582 as a starting model. The structure was refined by molecular dynamics optimization and the restrained least-squares method to a crystallographic R-value of 0.205. However, the current model gave an electron-density of the side-chain regions of several residues close to the N-terminus quite different from those expected from the amino acid sequences reported. Very recently, two kinds of azurins (Az-I and Az-II) were isolated from this bacterium by a slightly modified purification method and have been characterized and found to have different CD spectra. On analysis of amino acid sequences around the N-terminus, the second azurin (Az-II) was proved to be a new type of azurin in this bacterium. It was consequently revealed that the current model corresponds to a new type of azurin because of the complete agreement between the electron-density and the amino acid sequence of the newly determined 20 residues from the N-terminus. Determination of the whole amino acid sequence of this azurin and further refinement are in progress.

Alcaligenes↗
PubMed1994

Legionella pneumophila growth restriction and cytokine production by murine macrophages activated by a novel Pseudomonas lipid A.

Peritoneal exudate macrophages from A/J mice activated by purified lipid A preparations from Pseudomonas vesicularis, which contain 2,3-diamino-2,3-dideoxy-D-glucose disaccharide phosphomonoester as the lipid A backbone, restricted the growth of Legionella pneumophila, an intracellular opportunistic bacteria which readily grows in otherwise permissive macrophages from susceptible A/J mice and induced production of the proinflammatory cytokines interleukin 1 and tumor necrosis factor alpha. Activation of the macrophages was similar to that which occurred after stimulation with more conventional lipid A from other bacteria such as salmonellae. A purified fraction A3 preparation from the Pseudomonas lipid A, which lacked only 1 mol of amide-linked fatty acid, in comparison with another fraction (A2), which contained the fatty acid, also markedly activated the usually permissive macrophages from susceptible A/J mice to resist growth of the legionellae. The fraction A3 also induced both interleukin and tumor necrosis factor alpha. These results show that this novel lipid A from P. vesicularis can activate macrophages to resist infection with an opportunistic bacterium in a manner similar to that induced by conventional enterobacterial lipid A and that the hydrophobic portion of this Pseudomonas molecule may have an important role in activation of macrophages.

Animals↗
PubMed1994

Magnetic resonance imaging of young and aged rat brains under a magnetic field of 7.05 T.

Using a homemade MR imaging probe (Helmoholtz coil), MR images of brains of 5-week-old and 23- or 24-month-old Wistar rats were taken under a magnetic field of 7.05 T (Tesla). The probe was designed to fit the rat head and made by winding thin copper film round an acrylic tube with a 5-cm i.d., 10-cm length and 2-mm thickness. This was adjusted to resonate with the 300 MHz radiofrequency corresponding to the resonance frequency of 1H under a magnetic field of 7.05 T. MR images were obtained by T1-weighted and two-dimensional Fourier transformation techniques. The sagittal and coronal sections were imaged in 1-mm-thick slices. The size of the data matrix was 128 phase-encoded steps. Each image was obtained through eight acquisitions. A comparison of the MR images with those semi-microscopically taken at the same position of the coronal section revealed that the cerebral cortex, hippocampus, hypothalamus and thalamus were clearly imaged by this probe. With aging, MR images of cerebral cortices were observed with decreased signal intensities. Enlargement of the third ventricles and hypertrophy of cranical parietal bones were also recognized in sagittal MR images of aged rats. These observations were more marked in males than in females. From these observations it was concluded that this probe was applicable for MR imaging of rat brains under a magnetic field of 7.05 T.

Aging↗
PubMed1994

Meningioma associated with intratumoral abscess formation--case report.

A rare case of meningioma associated with intratumoral abscess formation occurred in a 64-year-old female presenting with septic meningitis and a right frontal mass lesion after a gynecological operation under spinal anesthesia. The mass lesion was totally removed and revealed as an incidental meningioma with an intratumoral abscess. Hematogenous infection of Bacteroides oralis was thought to be the cause of the intratumoral abscess formation.

Brain↗