Search PubMed⌕ Search

Biomedical subjects

T Katayama

Publications and source records attributed to T Katayama.

At least 109 records · Page 6Linked to original sources
PubMed1998

Characterization of fibronectin-related substances in normal and passive Heymann nephritis rats.

The excretion mechanism of fibronectin (FN)-related substances into the urine of normal and passive Heymann nephritis (PHN) rats was studied using enzyme immunoassay and immunoblot analysis. In normal rats, a small amount (0.20+/-0.067 microg/d) of FN-related substances, composed of 55- and 65-kDa FN fragments derived from the central cell-binding (Cell) domain of FN, were constitutively excreted into the urine. When PHN was induced in rats by the injection of an anti-Fx1A antibody, an increased excretion (4.96+/-3.51 microg/d) of intact FN and large (Mr > 100-kDa) FN fragments containing the Cell and the other functional domains were seen. The PHN induction also caused the appearance of a considerable amount of Cell domain-containing FN fragments in plasma. Both the renal cortex homogenates of normal and PHN rats were capable of degrading plasma FN to generate the Cell domain-containing large FN fragments. Degradation of FN by the renal cortex homogenate was shown to be due to metal and/or thiol proteinase(s). These results suggest that the PHN-induced urinary excretion of FN fragments may be due to the degradation of plasma FN by renal proteinases that may be leaked upon PHN induction.

Animals↗
PubMed1998

Q wave and non-Q wave myocarditis with special reference to clinical significance.

This study was designed to evaluate the differences in clinical findings between patients with and without Q waves in acute myocarditis. Among a total of 24 patients, eleven patients had Q waves and thirteen did not. Echocardiographic findings, in-hospital complications and follow-up results were compared between the two groups. In the acute stage, the Q wave group showed significantly higher creatine kinase (CK) values and a more impaired left ventricular ejection fraction than the non-Q wave group (40 +/- 11% vs 57 +/- 10%, p < 0.001). Transient left ventricular hypertrophy was also prominent in the Q wave group. The incidence of cardiogenic shock (55%) and conduction disturbances (64%) were higher in the Q wave group than in the non-Q wave group (0% and 15%, respectively). In-hospital mortality rate was 27% in the Q wave group and 8% in the non-Q wave group, respectively. Since rapid improvement occurred in survivors with Q waves, long-term prognosis was favorable for the two groups. In conclusion, Q waves might indicate a more severe course in early illness.

Adrenal Cortex Hormones↗
PubMed1998

Spontaneity in dementia: an analysis of 696 institutionalized elderly patients.

Activities of daily living (ADL), mental function, spontaneity, emotion and problematic behaviors were compared in elderly patients with hip fracture, hemiplegia, hemiparesis, senile dementia of Alzheimer type and multi-infarct dementia. Osteoarthropathy patients with normal intelligence served as a control group. ADL was most strongly affected by spontaneity, then, by intelligence. The contributions of emotion and problematic behaviors were not very marked.

Activities of Daily Living↗
PubMed1998

[Report of national survey on death due to tuberculosis in 1994 in national hospitals and the treatment and prognosis of tuberculous patients with mechanical ventilation].

1. National survey on died patients with active tuberculosis (tbc) or tbc sequelae had been held in national hospitals every five year from 1959 (3433 cases) to 1994 (688 cases). In 1994, 330 patients died due to pulmonary tbc. Recent study revealed the decreased rate of death due to operation, or far advanced cavitary cases, and the increased rate of nontuberculous death, aged people (> 60 yrs), and nontuberculous complications. Main causes of death in pulmonary tbc were lung insufficiency (about half) and general weakness (almost one fifth) in any survey. Rapid progression of pulmonary tbc had been increased cause of death (20.9% in 1994). Main attributable factors of death in 1994 in pulmonary tbc cases were severe condition on admission (38.4%), disturbed lung function (31.2%) and old age (33.2%). Delayed treatment (13.9%) and complications (12.1%) were increasing factors. Early death within 3 months from onset in 1994 was seen in patients < 60 yrs as well as in patients > 80 yrs. Severity due to delayed treatment and rapid progression were supposed to the causes of early death. 2. During 1994 to 1997, mechanical ventilation (MV; > 24 hours) was applied to 18 patients with active pulmonary tuberculosis; 10 acute respiratory failure (ARF), 5 chronic respiratory failure (CRF), 2 central nervous system tbc and 1 hemoptysis. Only one ARF case and three CRF ones survived. ARF cases had low PaO2/FIO2 (about 100), low albuminemia, short MV period (7 cases: < 7 days) and steroid therapy (9 cases). CRF cases had higher PaO2/FIO2 (294), longer MV period (4 cases: > 30 days) and all CO2 narcosis. 3. Noninvasive positive pressure ventilation (NIPPV) was applied to 23 patients with pulmonary tbc sequelae. In 13 patients with stable chronic respiratory failure (mean PaO2 91 mmHg, PaCO2 82 mmHg) 10 continued NIPPV and started home mechanical ventilation (HMV). In 10 patients with acute on chronic respiratory failure (mean PaO2 61 mmHg, PaCO2 92 mmHg) 2 patients fell into tracheal intermittent positive pressure ventilation (TIPPV). Eight patients recovered with NIPPV and 5 started HMV. NIPPV is supposed to be very effective to treat severe chronic hypercapmic respiratory failure.

Adult↗
PubMed1998

In vivo characterization of T-794, a novel reversible inhibitor of monoamine oxidase-A, as an antidepressant with a wide safety margin.

T-794 is a new reversible inhibitor of MAO type A. In order to predict its clinical utility as an antidepressant, we examined its pharmacological profile (i.e., MAO inhibitory activity, antidepressant-like activity and safety) in vivo in rodents. The p.o. administration of T-794 potentiated L-5-hydroxytryptophan-induced symptoms with ED50 = 1.01 mg/kg (mice) or 1.15 mg/kg (rats), and L-dopa-induced behavior with ED50 = 5.90 mg/kg (mice), whereas it did not alter the effect of beta-phenylethylamine even at 100 mg/kg (mice). In the L-5-hydroxytryptophan test in rats, the activity of T-794 (at twice the dose of ED50) disappeared by 8 h; the duration of action was similar to that of moclobemide. These results confirm the previous biochemical results that MAO-A inhibition by T-794 is highly selective and of short duration. T-794 was effective in three animal models of depression: reserpine reversal (mice, rats), behavioral despair test (mice) and learned helplessness (rats). In these tests, it had potency similar to or greater than moclobemide, tranylcypromine or imipramine. The p.o. administration of T-794 (30 mg/kg) did not affect the pressor effect of tyramine in anesthetized rats, whereas moclobemide (30 mg/kg) and tranylcypromine (6 mg/kg) potentiated the effect. Acute toxicity of T-794 proved to be very low (maximal tolerated dose > 2 g/kg p.o.) in contrast to brofaromine (maximal tolerated dose = 150 mg/kg p.o.). Unlike tricyclic antidepressants, T-794 did not prevent the oxotremorine-induced tremor even at 100 mg/kg p.o.; in this it demonstrated a lack of the anticholinergic activity. These results suggest that T-794 is an effective and particularly safe antidepressant and that it may make an important contribution in the treatment of depressive disorders.

Animals↗
PubMed1998

[A case of spastic paraparesis with mental deterioration and markedly thin corpus callosum--callosal dysfunction demonstrated by magnetic stimulation].

We have studied function of the corpus callosum in a patient with spastic paraparesis with mental deterioration and markedly thin corpus callosum using magnetic stimulation methods. In a 21-year-old woman with slowly progressive gait disturbance, neurological examination showed mental deterioration, euphoria, spastic paraparesis, bilateral Babinski's sign, and hyperesthesia caudal to the eighth thoracic level. No abnormalities were observed in electroencephalograms. Magnetic resonance imaging (MRI) studies of the brain showed cerebral cortical atrophy, markedly thin corpus callosum, and dilated cavum septum pellucidum and cavum Vergae, but spinal cord MRIs showed no abnormalities. The lysosomal enzyme activities, whose reduction was known to cause leukodystrophy, were all normal. Very long chain fatty acid was not increased in her blood, which is against adrenoleukodystrophy. She had no anti-HTLV-1 virus antibody. Based on these clinical features and the results of biochemical analyses, we diagnosed this patient as having spastic paraplegia associated with hypoplasia of the corpus callosum (Nojima and Iwabuchi). We performed three studies on the central motor pathways in this patient. The latencies of responses recorded from upper or lower limb muscles were all within the normal range, despite that the thresholds were slightly increased. This suggests that axonal degeneration occurs in the central motor pathways, which is consistent with the autopsy findings of a patient with hereditary spastic paraplegia associated with hypoplasia of the corpus callosum. Connection between the bilateral motor cortices was investigated by magnetic stimulation of both motor cortices. The suppression of the motor cortex evoked by stimulation of the contralateral motor cortex through the corpus callosum was absent in this patient. Intracortical inhibition within the motor cortex was demonstrated to be normal by a paired-magnetic stimulation technique. Based on the results of these results of these two experiments, we conclude that the function of the corpus callosum was disturbed in the present patient. This report first shows the functional abnormality of the extremely thin corpus callosum in a patient with hereditary spastic paraplegia associated with hypoplasia of the corpus callosum.

Adult↗
PubMed1998

Description and valuation of health-related quality of life among the general public in Japan by the EuroQol.

OBJECTIVE: Health-related quality of life plays an important role in assessing the effectiveness of health care. The EuroQol is a generic instrument for describing and valuing health-related quality of life. To elicit health state descriptions and their preferences among the general public in Japan and compare them with cross-national data, a feasibility study for applying the EuroQol to the general public in Japan was carried out. SUBJECTS AND METHODS: The subjects were 120 people aged 40s-60s randomly selected in a suburban area at Aichi Prefecture in Japan. In assessing health states and their preferences, the EuroQol valuation instrument (version 12, 1991) translated into Japanese was used. The questionnaires were distributed and collected by public health nurses. The valid responses (rate) were 89 (74%). RESULTS: The mean scores (raw scores) using the visual analogue scale (VAS) for one's own health was 89.2. No statistically significant difference in VAS scores was observed for both sex and age. The contribution ratio of own health status, sex and age was 0.326 (p < 0.0001). The main independent variables were three dimensions of health status. Valuations for core health states varied from 96.3 (no problem in each health status) to 6.8 (dead). These VAS scores in Japan were correlated with those from other countries (p < 0.001). A multivariate analysis indicated that bias from own health status on preference valuations for core health states was not observed. CONCLUSION: The health states and their preferences among the general public in Japan were estimated by using the EuroQol. The results show the feasibility of evaluation for health states quantitatively. Moreover, this study suggested cross-national and cross-cultural applicability of the EuroQol.

Adult↗
PubMed1997

Expression of zinc transporter gene, ZnT-1, is induced after transient forebrain ischemia in the gerbil.

To elucidate the molecular mechanisms underlying neuronal death after transient forebrain ischemia, we cloned genes expressed after transient forebrain ischemia in the Mongolian gerbil by a differential display method. A gerbil homolog of rat zinc transporter, ZnT-1, which transports intracellular Zn2+ out of cells, was isolated. Its expression became detectable exclusively in pyramidal neurons of the CA1 region 12 hr after ischemia and reached a maximum from day 1 to day 2 as shown by in situ hybridization. By day 7, expression had disappeared entirely from the cells in the CA1 region, because the neurons had died. No other brain regions exhibited such a significant level of ZnT-1 mRNA expression during this period. Zn2+ was shown to accumulate in CA1 pyramidal neurons expressing ZnT-1 mRNA after the ischemia by using zinquin, a zinc-specific fluorescent dye. When primary hippocampal neurons were exposed to a high dose of Zn2+, ZnT-1 mRNA accumulated. These results suggest that the induction of ZnT-1 mRNA observed in CA1 neurons was caused by an increase in the intracellular Zn2+ concentration. It was reported recently that Zn2+ chelator blocked neuronal death after ischemia and that the influx of Zn2+ might be a key mechanism underlying neuronal death. The induction of ZnT-1 mRNA in CA1 pyramidal neurons fated to die after transient ischemia is of interest to the study of postischemic events and the molecular mechanisms underlying delayed neuronal death.

Amino Acid Sequence↗
PubMed1997

Negative control of DNA replication by hydrolysis of ATP bound to DnaA protein, the initiator of chromosomal DNA replication in Escherichia coli.

DnaA protein, the initiation factor for chromosomal DNA replication in Escherichia coli, is activated by ATP. ATP bound to DnaA protein is slowly hydrolyzed to ADP, but the physiological role of ATP hydrolysis is unclear. We constructed, by site-directed mutagenesis, mutated DnaA protein with lower ATPase activity, and we examined its function in vitro and in vivo. The ATPase activity of purified mutated DnaA protein (Glu204-->Gln) decreased to one-third that of the wild-type DnaA protein. The mutation did not significantly affect the affinity of DnaA protein for ATP or ADP. The mutant dnaA gene showed lethality in wild-type cells but not in cells growing independently of the function of oriC. Induction of the mutated DnaA protein in wild-type cells caused an overinitiation of DNA replication. Our results lead to the thesis that the intrinsic ATPase activity of DnaA protein negatively regulates chromosomal DNA replication in E. coli cells.

Adenosine Diphosphate↗
PubMed1997

Purification, cDNA cloning, and characterization of a new serpin with megakaryocyte maturation activity.

A new member of the serine protease inhibitor (serpin) superfamily with megakaryocyte maturation activity was purified, and its cDNA was cloned and characterized. The predicted amino acid sequence consisting of 380 residues was unique and was 38% identical to the serpin plasminogen activator inhibitor type 2 (PAI-2). The recombinant factor expressed in Chinese hamster ovary cells showed species-specific activity on the induction of megakaryocyte maturation in vitro. When injected into mice, the factor indeed elicited an increase in the number of platelets in plasma. The sequence alignment indicated that the factor possessed a lysine residue at the P1 position, suggesting that it might function as an inhibitor of Lys-specific proteases. Although we could not show any inhibitory activities toward several known Lys-specific proteases, we detected the activity toward protease activity present in the culture supernatant of COLO 201 cells. These results suggested that the protein might influence the maturation of megakaryocytes via action as a serpin.

Amino Acid Sequence↗
PubMed1997

Amounts of proteins altered by mutations in the dnaA gene of Escherichia coli.

We identified proteins whose amounts were altered in a temperature-sensitive dnaA46 mutant of Escherichia coli. Proteins whose amounts were increased in the mutant were serine hydroxymethyltransferase, beta-ketoacyl [acyl carrier protein] synthase II, long-chain fatty acid transport protein, and UDP-glucose 4-epimerase, while the decreased ones were flagellin and D-ribose-binding protein. Transformation of the mutant with a plasmid containing the wild type dnaA gene complemented the phenotype. As pulse-labeling experiments revealed that the rates of synthesis of the proteins were altered in the mutant, DnaA protein may be involved in expression of these proteins.

Amino Acid Sequence↗
PubMed1997

Conformational transition of DnaA protein by ATP: structural analysis of DnaA protein, the initiator of Escherichia coli chromosome replication.

DnaA protein binds to the chromosomal origin (oriC) to initiate DNA replication. We developed an efficient system for purification of DnaA protein which will facilitate physicochemical analysis of the protein. The yield of DnaA protein was increased at least 6-fold compared to an available method being used, and over 22 mg of the protein were obtained from only 100 g of cells. DnaA protein purified by this procedure showed an indistinguishable affinity for ATP, and activity for in vitro replication of oriC plasmid. The process of denaturation of DnaA protein, which was blocked by ATP, was monitored by intrinsic fluorescence and circular dichroism. Analysis of circular dichroism revealed that DnaA protein is rich in alpha-helices, and that ATP-binding leads to a significant transition of protein conformation in that the content of alpha-helices is decreased. This is the first evidence indicating that ATP-binding profoundly affects conformation of DnaA protein.

Adenosine Triphosphate↗