Search PubMed⌕ Search

Biomedical subjects

A Kato

Publications and source records attributed to A Kato.

At least 505 records · Page 28Linked to original sources
PubMed1992

Microvasculature of normal and hydropic labyrinth.

The microvasculature of the inner ear in guinea pigs and humans was observed with a scanning electron microscope using corrosion casting method. Alterations in the inner ear vasculature which occurred in association with experimental endolymphatic hydrops were also investigated. The results thus obtained are summarized as follows: 1. In the cochlea and vestibule, the arteries, coiled arterioles, and the veins are endowed with their respective characteristic morphologic features and play a role in the regulatory mechanisms of circulation. 2. The point in humans which is most different from guinea pigs was that coiled arterioles in the cochlea and the coil-like traveling of the anterior vestibular artery is not outstanding. 3. Arteriovenous anastomoses were demonstrated to exist in lateral wall of cochlea and utricular macula, a finding suggesting the existence of a regulatory mechanism for local blood flow. 4. Endolymphatic hydrops was noted to be preferentially associated with vascular abnormalities in the lateral wall of the cochlear duct and in the saccular macula, among other vestibular structures.

Animals↗
PubMed1992

[Laboratory tests in acute renal failure].

This review is focused on the roles of laboratory test in acute renal failure (ARF). The roles of the laboratory test changes along with the alterations in clinical features and with the advances of treatment. Recent acute renal failure is characterized by the following three features: most of the ARF develops in hospitals, the frequency of nonoliguric ARF is increasing, and the association of other organ failure such as heart failure, liver failure or respiratory failure, increases the mortality rate. Hemodialysis is instituted in the early phase of ARF to enable the supply of enough nutriments and drugs. These features of recent ARF increases the importance of the frequent analysis of plasma creatinine in patients, who are at risk for ARF, to diagnose ARF at the onset. After the development of ARF, laboratory tests for the evaluation of other organ function is repeated. The development of new drugs increases the incidence of interstitial nephritis, and the advances in the therapeutic approach on systemic diseases (such as SLE or PN), which frequently develop ARF, alter the prognosis of these diseases. Since the early diagnosis of these diseases is important, it is necessary to develop noninvasive and reliable tests for the diagnosis of these diseases.

Acute Kidney Injury↗
PubMed1992

[Electron-microscopic observations on rat lungs after long term inhalation of diesel emissions--non-neoplastic lesions].

Non-neoplastic lesions in the respiratory organs of rats (F344) were investigated after exposure to heavy and light duty diesel emissions for 30 months. Pathological examinations of the lungs after every 6 months of exposure were performed by light and electron microscopy. Anthracosis caused by the inhaled diesel soot was the main morphological change observed in the lung. Foci of alveoli filled with alveolar macrophages engorged with diesel particles were scattered in the lung parenchyma. Marked changes observed in these areas consisted of intake of diesel particles by type 1 epithelium, hypertrophy and glandular proliferation of type 2 epithelium with many extended microvilli and increased number and size of lamellar inclusion bodies, focal increase of collagen fibers in the interstitium, and infiltration of particle-laden macrophages, neutrophils, mast cells and plasma cells into the interstitium of alveolar septa. Within the alveolar lumina there was marked accumulation of particle-laden macrophages or neutrophils and their debris, as well as laminated or scrolled materials discharged from the type 2 epithelium. The most marked changes observed in the airways were focal shortening of cilia and protrusions of non-ciliated cells, which were attributable mainly to the effects of gaseous components in the diesel exhaust. These morphological changes appeared in all the groups exposed to particle concentrations greater than 1 mg/m3 after 6 months' exposure, and were more marked with increase in particle concentration and with time.

Animals↗
PubMed1992

Fluorometric enzyme immunoassay of basic fibroblast growth factor with monoclonal antibodies.

We compared three different strategies for measuring basic fibroblast growth factor (bFGF) by fluorometric enzyme immunoassay (EIA). After optimizing conditions, we found that a primary anti-bFGF MAb directly conjugated with peroxidase gave the best detection limit for recombinant bFGF (approximately 30 ng/L, 3 pg/assay tube) in a two-site sandwich assay. The detection limit of methods based on biotinylated primary MAbs or on secondary antibodies followed by streptavidin-conjugated peroxidase was slightly lower than that of the above method. Using the most sensitive EIA examined in this study, we made a preliminary measurement of immunoreactive bFGF in sera of apparently healthy people and found it to be 190 (SD 32) ng/L (n = 48), in agreement with an earlier reported value (30-206 ng/L). Also, the concentration of immunoreactive bFGF in sera was above normal in 19 of 31 patients with stomach cancer.

Antibodies, Monoclonal↗
PubMed1992

[Coarctation of aorta with right aortic arch and anomalous left subclavian artery].

The occurrence of coarctation in patients with right aortic arch is extremely rare. We have encountered a 21-year-old man with anomalous left subclavian artery. He was diagnosed when he was 13. On angiography he exhibited a right aortic arch. The left common carotid artery, right common carotid artery and the right subclavian artery diverged from the proximal side of the coarctation. The left subclavian artery diverged from the distal side. The right brachial arterial pressures measured 158-72 mmHg, while the left brachial arterial pressures measured 98-80 mmHg. Clinical studies revealed no vascular ring and no other anomalies were found in this patient. An attempt at treatment was made with extra anatomical bypass grafting from the ascending aorta to the descending aorta. No pressure difference due to coarctation remained after operation.

Adult↗
PubMed1992

[Imbalance of amino acid metabolism in fulminant hepatitis and its management].

Fulminant hepatitis shows characteristic imbalance of amino acid levels; increased aromatic amino acid (AAA) and methionine. Elevated plasma AAA may cause hepatic encephalopathy and BCAA-enriched amino acids solution (BCAAs). Glucagon-Insulin (G-I) therapy and artificial liver support system have been proposed to correct the imbalance of amino acids. BCAAs and G-I therapy correct the aberrant amino acid patterns and artificial liver support system, including plasma pheresis, and charcoal haemoperfusion has also been used to reduce plasma amino acids levels. While imbalance of amino acids level in fulminant hepatitis is a result of acute necrosis of a large proportion of hepatocytes, careful and sufficient management of the disease is essential to normalize amino acid profiles.

Amino Acids, Branched-Chain↗
PubMed1992

Tumor dormancy and the effect of selected drugs on the tumor-dormant state.

An animal model for studying tumor dormancy was established by two-way selection of tumor-progressive and nonprogressive (tumor-dormant state) ddY mice in the same basal stock. In the tumor-progressive (prg) substrain of mice, Ehrlich ascites tumor cells (2 x 10(7)) subcutaneously inoculated into the dorsal skin formed a progressive solid tumor. In the tumor-dormant substrain (drm) of mice, the same tumor cells did not grow at all but formed a small caked nodule (1 to 3 mm in diameter) within 1 week. Some of the tumor cells persisted in the nodule at least 3 months without apparent mitotic figures. Such dormant tumor cells emerged and revealed outgrowth to overt solid tumors after they were transplanted into the dorsal skin of prg mice or into athymic mice (C57BL/6J nu/nu). To estimate the predisposition of drm mice to form tumors, the effect of certain drugs on the tumor-dormant state was examined. Estradiol, progesterone, dexamethasone, prostaglandin E2, Cyclosporin A, and collagenase all failed to promote the emergence of dormant tumor cells in drm mice.

Animals↗
PubMed1992

[Lymphomatoid granulomatosis (LYG) occurring in a patient with follicular lymphoma during remission].

A 49 years-old man presented with dry cough, low grade fever, and abnormal shadow on a chest X-ray. He had suffered from follicular lymphoma of the liver 5 years previously. He received irradiation therapy in combination with chemotherapy for approximately three years and had been in complete remission. Physical and radiological examination revealed pleural effusion and softly dense masses in the right lung. The laboratory data were within normal limits. He was diagnosed as having lymphomatoid granulomatosis (LYG) by open lung biopsy. The lung lesion was mainly infiltrated with T cells. The patient received prednisolone and the lung lesions disappeared. However, when a lung mass was noted two months later, he started to receive combination chemotherapy consisting of cyclophosphamide, adriamycin, vincristine, and prednisolone every three months. He has not shown relapse of LYG so far. To investigate the association between the preceding follicular lymphoma and subsequent LYG at this time, DNA analysis using the PCR technique was carried out. The LYG lesion did not show a rearranged band for the JH probe, while the paraffin-embedded specimen of the preceding follicular lymphoma had shown rearranged band for the JH band. Southern blot analysis of the LYG lesion, showed no rearrangement for TCR beta, gamma or JH probe. These findings indicate that the LYG was different from the preceding follicular lymphoma in terms of origin. LYG is considered to be induced in the immunosuppressive state due to lymphoma.

Combined Modality Therapy↗
PubMed1991

Interferon-inducible mouse Mx1 protein that confers resistance to influenza virus is GTPase.

The murine Mx1 protein is an interferon-inducible nuclear protein and confers resistance to influenza virus infection even though the resistance mechanism is yet unclear. The Mx1 protein contains a tripartite GTP-binding domain consisting of GXXXXGKS, DXXG, and T/NKXD motifs. In the GTPase gene superfamily such as p21ras protein, signal-transducing G protein, and translation elongation factor, the GTPase activity plays a key role in each protein function. Here we show that GTPase activity is indeed associated with the intact Mx1 protein purified from Escherichia coli expressing Mx1 cDNA. Amino acid substitution within the GTP-binding motif led to significant reduction in the GTPase activity. Yeast vacuolar protein sorting (VPS1) protein and the rat microtubule-associated mechanochemical enzyme dynamin were found to be homologous to Mx1 not only in the tripartite GTP-binding motif, but also in the amino-terminal region of approximately 300 amino acids in length. The function of Mx1 is discussed in comparison with these proteins.

Amino Acid Sequence↗
PubMed1991

Heme peptide as a model substance for halogenomethane activation and heme modification.

Octa-heme peptide (CHP) obtained from Candida krusei cytochrome c was tested for suicidal activation of halogenomethanes. Under anaerobic conditions, CHP was kept in the reduced state in the presence of NADPH and NADPH-cytochrome P-450 reductase. Addition of CBrCl3 to the reduced CHP caused spectral changes such as rapid disappearance of alpha and beta bands and gradual decrease in the gamma-peak height, accompanied by oxidation of NADPH. Heme content of the reaction mixture, determined as pyridine hemochrome, also decreased NADPH dependently. CCl4 was less effective than CBrCl3, while CHCl3 had almost no effect. N-tert-butyl-alpha-phenylnitrone (PBN) suppressed the CBrCl3-induced heme damage, and resulted in the formation of radical adduct .PBN-CCl3 as evidenced by ESR spectroscopy. Radical formation was also observed with CCl4. The CHP damage induced by CBrCl3 was also accompanied by the release of Br- about 11-12-times molar excess of CHP, whereas the release of CHCl3 was about 20% that of Br-.FD-MS assay of the product of CHP reaction suggested that 10 trichloromethyl radicals bonded with CHP. Thus, CBrCl3 undergoes single-electron reduction in the presence of reduced CHP to trichloromethyl radicals, which covalently bind to CHP molecules. Heme peptide may be a useful tool in the study of mechanisms involved in the destruction of cytochrome P-450 by halogenomethanes.

Amino Acid Sequence↗
PubMed1991

A novel recombinant tumor necrosis factor-alpha mutant with increased anti-tumor activity and lower toxicity.

We prepared a novel recombinant tumor necrosis factor-alpha (TNF) mutant (mutant 471), in which 7 N-terminal amino-acids were deleted and Pro8Ser9Asp10 was replaced by ArgLysArg, and compared its biological activity with that of wild-type recombinant TNF. Mutant 471 had a 7-fold higher anti-tumor activity against murine L-M cells in vitro, and a higher binding activity to TNF receptors on L-M cells, than wild-type TNF. Furthermore, mutant 471 showed a higher anti-tumor effect on murine Meth A-HM tumors transplanted into BALB/c mice, with complete regression of the tumors being observed in the animals. The possible cachectin activity of mutant 471 was almost the same as that of wild-type TNF. The acute lethal toxicity of mutant 471 in beta-D-galactosamine-sensitized C3H/HeJ mice was 18 times lower than that of wild-type TNF. These results suggest that mutant 471 might be a more promising anti-cancer agent than wild-type TNF.

Amino Acid Sequence↗
PubMed1991

Positive and negative regulations of plasmid CoLIb-P9 repZ gene expression at the translational level.

Expression of the repZ gene involved in DNA replication of the ColIb-P9 plasmid depends on translation of a transcribed repZ leader sequence (repY) and is negatively regulated by Inc RNA, the product of the inc gene and a countertranscript to RepZ mRNA. To further understand the regulatory loop of repZ expression, we isolated and characterized replication-defective ColIb-P9 mutants that affected the level of repZ expression. Here we report that mutations occurring in two complementary sequences, one (5'GGCG3') in the inc region and one in the repY region, reduce the level of repZ expression without affecting transcription. The mutations in one complementary sequence were suppressed by compensatory base changes in the other sequence, restoring the ability of repZ expression. These results indicated that interaction by base pairing between the two complementary sequences of RepZ mRNA was essential for repZ translation. The two sequences, separated by 107 bases from each other, have a potential to form a novel pseudoknot in the RepZ mRNA leader. We also found that some mutations in the 5'GGCG3' sequence altered the specificity of Inc RNA, thereby reducing significantly its regulatory activity. Thus, this single specific sequence is involved in both positive and negative regulations for repZ expression. Possible regulatory mechanisms of repZ expression are discussed.

Amino Acid Sequence↗
PubMed1991

Quantitative determination of N-glycolylneuraminic acid expression in human cancerous tissues and avian lymphoma cell lines as a tumor-associated sialic acid by gas chromatography-mass spectrometry.

N-Glycolylneuraminic acid (NeuGc) is distributed in most animals except humans and chickens. However, human and chicken cancerous tissues often synthesize this heterophilic sialic acid as a tumor-associated Hanganutziu-Deicher antigen [M. Naiki and H. Higashi, Adv. Exp. Med. Biol., 152: 445-456, 1982; H. Higashi et al., Cancer Res., 45: 3796-3802, 1985]. In this paper, NeuGc in human cancerous tissues and chicken Marek's disease lymphoma cell lines was determined quantitatively with gas chromatography-mass spectrometry analysis using mass fragmentography. The detectable limit of NeuGc was 40 pg (0.12 pmol) in each injection using 5 ng of trideuteriomethyl ester trideuteriomethyl glycoside of the sialic acid as an internal standard sample when a pair of ions at m/e 386 and 389 was chosen for ion monitoring. NeuGc was detected in ganglioside-rich fractions of various human cancerous tissues from 5 of 8 patients examined but was not detected in glycosphingolipids of normal human tissues. The contents of NeuGc in these cancerous tissues ranged from 0.02 to 0.5% of the total sialic acid content. NeuGc was also detected in freeze-dried samples of 5 different cell lines from chicken Marek's disease lymphomas but was not detected in a cell line from chicken lymphoid leukosis lymphoma and normal chicken skeletal muscle tissue. The contents of NeuGc in the positive cell lines ranged from 0.03 to 0.11% of the total sialic acid content. These results indicate that NeuGc can be synthesized in both humans and chickens in some cancers.

Animals↗
PubMed1991

Analysis of the 5' flanking region responsible for the endosperm-specific expression of a rice glutelin chimeric gene in transgenic tobacco.

The 5' upstream region of the rice storage protein type II glutelin gene was examined for its regulatory function in transgenic tobacco. Chimeric genes containing 5' flanking regions of the glutelin gene transcriptionally fused to the beta-glucuronidase (GUS) reporter gene were introduced into the tobacco genome by Agrobacterium tumefaciens-mediated gene transfer. The chimeric genes were expressed specifically in developing seeds, as opposed to leaves and stems, of the transgenic tobacco. Histochemical analysis revealed that the GUS activity was restricted to the endosperm tissue. A deletion series of the 5' flanking region was created from position -1329 to -74 relative to the transcriptional initiation site and similarly examined in transgenic tobacco. Measurement of GUS activity of the seeds from the transgenic plants bearing the chimeric genes indicated that the region between positions -441 and -237 was required for the temporal and endosperm-specific expression of the GUS activity in tobacco. RNA analysis by northern blotting confirmed the importance of the -441 to -237 region. Addition of up to 888 bp to the -441 deletion resulted in little increase in GUS activity, although all constructs expressing the GUS gene showed a similar tissue and temporal regulation pattern.

Base Sequence↗
PubMed1991

Sequence of three members and expression of a new major subfamily of glutelin genes from rice.

Three members have been isolated of an additional glutelin gene subfamily, named subfamily B, consisting of about five members per haploid rice genome. Restriction fragment length polymorphism analysis showed major differences between Japonica and Indica lines, indicating the divergence of the subfamily since the split between the two varieties. While corresponding exons of the subfamily B showed 80 to 88% nucleotide sequence homology, those exons were only 60-65% homologous to those of the glutelin A subfamily, distinguishing them from the subfamily A. Intron position and derived polypeptide structure, in addition to the nucleotide sequence, confirm the subfamily B members as glutelins. Analysis of RNA from seeds of different stages of development showed that the subfamily B members were expressed at the same time as those of subfamily A, demonstrating coordinated regulation of the two subfamilies.

Amino Acid Sequence↗