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Biomedical subjects

N Kato

Publications and source records attributed to N Kato.

At least 577 records · Page 32Linked to original sources
PubMed1994

Risk factors for SIDS in Japan: a record-linkage study based on vital statistics.

This study examines the effect of items as reported on birth certificates on sudden infant death. We linked infant death certificates with birth certificates for the infants born in 1989 to residents of the Tohoku, Tokai and Kyushu regions in Japan (n = 409,679), that is, about one-third of the infants born in Japan that year. The mortality rate from sudden infant death, including 88 deaths from sudden infant death syndrome (SIDS) and 17 deaths from instantaneous death, was 25.6 per 100,000 live births. Elevated risk of sudden infant death was associated with low birthweight, late birth order, illegitimacy, male gender and young maternal age. These results correspond to previous studies from Western countries, suggesting a similar pattern for SIDS in Japan.

Birth Weight↗
PubMed1994

Patients with methamphetamine psychosis admitted to a psychiatric hospital in Japan. A preliminary report.

To examine the clinical characteristics of methamphetamine (MAP) psychosis in Japan, we evaluated 104 patients with MAP psychosis (80 men and 24 women) admitted to the closed psychiatric units of Tokyo Metropolitan Matsuzawa Hospital between 1988 and 1991. There has recently been a steep increase in the number of admissions for MAP psychosis, reflecting the growth of the epidemic of MAP abuse in Japan. Although more than half of the patients were discharged within one month, 16 patients were hospitalized for more than 3 months. Most of the patients showed paranoid psychotic state similar to schizophrenia, consistent with previous reports. Despite the abstinence from MAP and antipsychotic medication, psychotic symptoms tended to persist in some of the patients. The etiological role of MAP psychosis in the development of long-lasting psychotic state was discussed.

Adolescent↗
PubMed1994

Molecular characterization of an enterobacterial metallo beta-lactamase found in a clinical isolate of Serratia marcescens that shows imipenem resistance.

A clinical isolate of Serratia marcescens (TN9106) produced a metallo beta-lactamase (IMP-1) which conferred resistance to imipenem and broad-spectrum beta-lactams. The blaIMP gene providing imipenem resistance was cloned and expressed in Escherichia coli HB101. The IMP-1 was purified from E. coli HB101 that harbors pSMBNU24 carrying blaIMP, and its apparent molecular mass was calculated to be about 30 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Kinetic studies of IMP-1 against various beta-lactams revealed that this enzyme hydrolyzes not only various broad-spectrum beta-lactams but also carbapenems. However, aztreonam was relatively stable against IMP-1. Although clavulanate or cloxacillin failed to inhibit IMP-1, Hg2+, Fe2+, or Cu2+ blocked the enzyme's activity. Moreover, the presence of EDTA in the reaction buffer resulted in a decrease in the enzyme's activity. Carbapenem resistance was not transferred from S. marcescens TN9106 to E. coli CSH2 by conjugation. A hybridization study confirmed that blaIMP was encoded on the chromosome of S. marcescens TN9106. By nucleotide sequencing analysis, blaIMP was found to encode a protein of 246 amino acid residues and was shown to have considerable homology to the metallo beta-lactamase genes of Bacillus cereus, Bacteroides fragilis, and Aeromonas hydrophila. The G+C content of blaIMP was 39.4%. Four consensus amino acid residues, His-95, His-97, Cys-176, and His-215, which form putative zinc ligands, were conserved in the deduced amino acid sequence of IMP-1. By determination of the amino acid sequence at the N terminus of purified mature IMP-1, 18 amino acid residues were found to be processed from the N terminus of the premature enzyme as a signal peptide. These results clearly show that IMP-1 is an enterobacterial metallo beta-lactamase, of which the primary structure has been completely determined, that confers resistance to carbapenems and other broad-spectrum beta-lactams.

Amino Acid Sequence↗
PubMed1994

Application of typing by pulsed-field gel electrophoresis to the study of Clostridium difficile in a neonatal intensive care unit.

Pulsed-field gel electrophoresis (PFGE) analysis of restriction pattern polymorphism was applied to type Clostridium difficile isolated from neonates hospitalized in a neonatal intensive care unit, and the results were compared with those of immunoblot analysis. C. difficile was isolated from fecal specimens of 41 (61%) of 67 neonates during a 5-month investigation. All of these neonates were asymptomatic. Fifty-five C. difficile isolates from 32 patients were analyzed by PFGE after digestion with SmaI and SacII endonucleases and by immunoblotting with 10 different antisera. Fifty-three of 55 isolates from 30 patients were identical by PFGE analysis after SmaI and SacII digestion and immunoblot analysis. Two isolates were different from each other and from the epidemic group by both PFGE and immunoblot analysis. All 53 epidemic isolates were nontoxigenic, while the two remaining isolates were toxigenic. These results suggest that nosocomial spread of nontoxigenic C. difficile infection in the neonatal intensive care unit and suggest that both PFGE and immunoblot are powerful typing tools for the epidemiological study of C. difficile.

Antibodies, Bacterial↗
PubMed1994

Genetic drift in hypervariable region 1 of the viral genome in persistent hepatitis C virus infection.

The hypervariable region 1 (HVR1) of the putative second envelope glycoprotein (gp70) of hepatitis C virus (HCV) contains a sequence-specific immunological B-cell epitope that induces the production of antibodies restricted to the specific viral isolate, and anti-HVR1 antibodies are involved in the genetic drift of HVR1 driven by immunoselection (N. Kato, H. Sekiya, Y. Ootsuyama, T. Nakazawa, M. Hijikata, S. Ohkoshi, and K. Shimotohno, J. Virol. 67:3923-3930, 1993). We further investigated the sequence variability of the HCV genomic region that entirely encodes the envelope proteins (gp35 and gp70); these sequences were derived from virus isolated during the acute and chronic phases of hepatitis in one patient, and we found that HVR1 was a major site for genetic mutations in HCV after the onset of hepatitis. We carried out epitope-mapping experiments using the HVR1 sequence derived from the acute phase of hepatitis and identified two overlapping epitopes which are each composed of 11 amino acids (positions 394 to 404 and 397 to 407). The presence of two epitopes within HVR1 suggested that epitope shift happened during the course of hepatitis. Four of six amino acid substitutions detected in HVR1 were located within the two epitopes. We further examined the reactivities of anti-HVR1 antibodies to the substituted amino acid sequences within the two epitopes. HVR1 variants in both epitopes within the HVR1 escaped from anti-HVR1 antibodies that were preexisting in the patient's serum.

Adult↗
PubMed1994

Hepatocellular carcinoma: treatment with a combination of transcatheter arterial chemoembolization and transportal ethanol injection.

PURPOSE: To evaluate the efficacy and complications of transportal ethanol injection (TPEI) combined with transcatheter arterial chemoembolization to achieve complete tumor necrosis and prevent intrahepatic metastases in patients with hepatocellular carcinoma (HCC). MATERIALS AND METHODS: In 13 patients with HCC, chemoembolization was performed with injection of a mixture of iodized oil and doxorubicin hydrochloride followed by administration of gelatin sponge; 1-4 weeks later, TPEI was performed with percutaneous transhepatic portography. Ethanol (15-65 mL) was injected in the portal veins around the tumor until occlusion. RESULTS: TPEI was successfully performed in all patients. Two patients subsequently underwent surgery; their tumors were resected completely. Two died of hepatic failure. Seven of the nine other patients showed no recurrence or intrahepatic metastasis during follow-up (7-42 months). Histologic examination, performed in nine patients, showed complete necrosis of tumor and scattered or severe necrosis of surrounding tissues. CONCLUSION: This treatment has a strong anticancerous effect and is expected to be used in treatment of properly selected patients with HCC.

Aged↗
PubMed1994

Characterization of nicotinamide methyltransferase in livers of mice bearing Ehrlich ascites tumors: preferential increase of activity.

There was a 2- to 7-fold increase in nicotinamide methyltransferase activity in the livers of mice and rats bearing seven different kinds of tumors compared with the respective control normal livers, while activity in the tumors themselves was hardly detectable. The activity in the liver started to increase markedly 3-7 days after i.p. transplantation of Ehrlich ascites tumors into the mice, maintaining a plateau up to death. Metabolic conversion of 14C-nicotinamide to 14C-N1-methylnicotinamide was 3-fold higher in the slices of the ascites tumor host liver than in the normal liver, but the conversion to other radioactive metabolites was not significantly different. Nicotinamide methyltransferase was finally purified 20,000-fold with a yield of 4% from the cytosolic fraction of the ascites tumor host liver by means of five purification steps. At every purification step, only one enzyme fraction was detected. The enzyme finally isolated exhibited a single protein band in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, with a molecular weight of 26,000. As for the compounds investigated, including the substrates for methyltransferases other than nicotinamide methyltransferase, only quinoline could be the substrate for enzyme activity. It is suggested that the increase in enzyme activity in the tumor host liver probably derived from the endogenous enzyme preexisting in the liver before tumor transplantation.

Animals↗
PubMed1994

Autoimmune myocarditis induced in mice by cardiac C-protein. Cloning of complementary DNA encoding murine cardiac C-protein and partial characterization of the antigenic peptides.

Autoimmune myocarditis is considered to play a major role in the pathogenesis of dilated cardiomyopathy. A new autoimmune myocarditis model was attained by repeated immunization using murine cardiac C-protein with the immunological adjuvant, Klebsiella pneumoniae O3 lipopolysaccharide. For further analysis of a pathological epitope, the cDNA encoding C-protein was isolated; a fusion protein encoded by part of this cDNA induced myocarditis in SMA mice as well as in three other strains: DBA/1J (H-2q), O20/A (H-2pz1), and SJL (H-2s). The nucleotide sequence and its deduced amino acid analysis revealed that this protein had immunoglobulin-like and fibronectin-like repeats. This study provides a new animal model of autoimmune myocarditis which may shed light on the pathogenesis of dilated cardiomyopathy.

Adult↗
PubMed1994

tsJT16, a cell cycle ts mutant of rat fibroblast defective in early G0/G1 transition, fails to induce G1-cyclin and cdk2 genes after serum stimulation at the nonpermissive temperature.

tsJT16 is a cell-cycle temperature-sensitive (ts) mutant derived from rat fibroblasts whose functional defect appears soon after the growth stimulation from G0 phase. In addition to c-fos, c-myc and ornithine decarboxylase gene, 7 primarily inducible genes, c-jun, KC, JE, 2F1, 2A9, egr-1, and egr-2, were further shown to be expressed after serum stimulation at both permissive and nonpermissive temperatures. However, expression of secondarily inducible genes, cyclin D1 and D3 and cdk2, was ts and was cycloheximide sensitive. Expression of cyclin C was not inhibited by cycloheximide but it was ts. Failure in expression of G1 cyclins and Cdk2 is suggested to be a causal event for inability of growth induction of tsJT16 at the nonpermissive temperature.

Animals↗
PubMed1994

Influence of endotoxin and lipid A on the renal handling and accumulation of gentamicin in rats.

The contribution of lipid A, an active component of endotoxin (LPS), to changes in the pharmacokinetics, renal handling and intrarenal accumulation of gentamicin induced by Klebsiella pneumoniae LPS was investigated in rats. Either LPS (250 micrograms/kg) or lipid A (equivalent to dose of LPS) was infused 2 h before the administration of gentamicin (10 mg/kg). The effects of LPS and lipid A on the intrarenal accumulation of gentamicin were also evaluated. Significant increases in the levels of plasma creatinine and blood urea nitrogen were observed in both the LPS and lipid A groups. Both LPS and lipid A induced significant decreases in the glomerular filtration rate (by approximately 30%) and systemic clearance of gentamicin (by approximately 25%). No changes in the fraction of urinary excretion (> 0.9) or steady-state volume of distribution of gentamicin were observed between either the control, LPS or lipid A groups. There were no significant differences among the three groups in the tubular reabsorption or intrarenal accumulation of gentamicin. The degree of effect of lipid A on the pharmacokinetics of gentamicin observed in this study was nearly equal to that of LPS. These results suggest that lipid A plays a major role in changes in the pharmacokinetics and renal handling of gentamicin induced by LPS.

Animals↗
PubMed1994

Uptake of remnant like particles (RLP) in diabetic patients from mouse peritoneal macrophages.

To investigate whether the remnant like particles (RLP), separated from serum by an immunoaffinity gel mixture of anti-apo B-100 and apo A-I monoclonal antibodies, are relevant to the initiation or progression of atherosclerosis, the incorporation of RLP into mouse macrophages was studied using histochemical and biochemical techniques. Remnant lipoproteins such as RLP are reported to contain a large quantity of chyloniron and very low density lipoprotein (VLDL) remnants, especially in diabetic patients. The RLP separated from the sera of 32 diabetic patients were found to be predominantly taken up into macrophages harvested from mouse abdominal cavities by the staining method applying oil red O. Furthermore, using 14C-oleate to prove the uptake of lipoproteins by macrophages, the uptake of RLP-VLDL, a VLDL fraction of RLP by ultracentrifugation, was the next highest to that of the oxidized LDL, which suggests that RLP-VLDL is also aggressively taken up by macrophages. The degree of uptake of RLP-VLDL by macrophages was positively correlated with HbA1c of these diabetic patients (r = 0.556, p < 0.01), irrespective of the ways of the treatment of diabetes. In conclusion, RLP can contribute to the foaming of macrophages, which in turn may explain the acceleration of atherosclerosis in diabetic patients.

Aged↗
PubMed1994

Bidirectional regulation of smooth muscle cell proliferation by IFN-gamma.

We studied the effects of interferon gamma (IFN-gamma), a T-cell lymphokine, on the proliferation and chemotaxis of vascular smooth muscle cells (SMC). Recombinant human IFN-gamma dose-dependently inhibited the proliferation of SMC cultured in the presence of 20% fetal calf-serum. It also inhibited PDGF-induced chemotaxis of SMC. Similar concentrations of IFN-gamma induced DNA-synthesis of SMC cultured in mitogen-depleted medium for 5 days. The inhibition and the stimulation of SMC proliferation were accompanied by concomitant decrease and increase in the number of PDGF receptors. Our study indicated that IFN-gamma is a bidirectional regulator of SMC proliferation.

Cell Division↗
PubMed1994

[Laparoscopic pelvic lymphadenectomy in prostate cancer].

We described the clinical results and efficacy of laparoscopic pelvic lymphadenectomy for localized prostate cancer. This procedure was followed by radical prostatectomy, if metastasis was not found in frozen section. In the presence of positive nodes, optional treatment, such as TUR or castration, other than radical prostatectomy was performed. We performed laparoscopic lymphadenectomy on twenty seven patients between April 1992 and September 1993. They range from 52 to 78 years in age and consist of 4 patients with stage A2, 17 with stage B, and 6 with stage C. We dissected the obturator lymph nodes on bilateral sides. The average operating time was 162 minutes (range 86 to 320 minutes). The average number of nodes removed from the right side was 7.1 +/- 5.9 and 6.1 +/- 4.5 from the left side, which was comparable to the number of lymph nodes obtained by open dissection. Colon injury occurred in one patient, which was managed by laparotomy procedure. Nodal metastases were found in 6 patients by frozen section, and in 10 patients by permanent section. This discrepancy suggested that two-staged operation might be preferable for the localized prostate cancer. Six patients were given suitable therapies besides radical prostatectomy. Laparoscopic pelvic lymphadenectomy is a safe and useful procedure for prostate cancer, especially for the patients who are likely to have nodal metastasis.

Aged↗
PubMed1994

Epidemics of aseptic meningitis due to echovirus 30 in Japan. A report of the National Epidemiological Surveillance of Infectious Agents in Japan.

Two rages of epidemic of aseptic meningitis (AM) due to echovirus 30 (E30) in Japan were analyzed with respect to two sources of information, AM incidence and E30 isolation, both gathered through the National Epidemiological Surveillance of Infectious Diseases. The first E30 epidemic spread throughout Japan in 1983 and ceased within the year. The second epidemic, starting in 1989, continued for the three successive years, and in the last year, 1991, the total E30 reports numbered 4,061, the largest number of a single virus type ever reported. Although the epidemic showed temporal and geographical shift and lasted for one or two years in some areas, most laboratories reported the largest number of E30 isolation in 1991. Among E30-yielding cases with clinical information during 1982-1992, the associating frequency with AM was as high as 82.5%. Other central nervous system involvements such as encephalitis, myelitis, encephalomyelitis and/or paralysis were reported in 36 E30-yielding cases and their monthly and age distributions were different from those of AM cases. The proportion of such disease among E30-yielding cases (0.60%) was close to that of other enteroviruses (0.56%). During the epidemics, E30 was isolated more frequently from cerebrospinal fluid than was E4 or E9 which prevailed coincidentally. E30 was most frequently isolated from cases of 4-7 years of age, sharing the common characteristic pattern of age distribution with other enteroviral meningitis. E30-yielding cases, however, involved a large number of older age groups than those of other enterovirus infections, and this tendency was the most pronounced in the first epidemic year, 1983. The contribution of these E30 epidemics on the yearly trend of clinically reported AM incidence and on the shift of its age distribution was also analyzed.

Adolescent↗
PubMed1994

Functional organization of corticocortical projections from area 17 to area 18 in the cat's visual cortex.

We used anatomical and physiological methods to study the functional organization of the association projection from area 17 to area 18 in the cat's visual cortex. Neurons in area 17 projecting to area 18 (revealed by retrograde transport of fluorescent tracer) tend to be clustered over regions of layer 4 receiving input from the ipsilateral eye (visualized by anterograde transneuronal tracing). Since the contralateral input overlaps these ipsilateral patches, the association cells lie preferentially in regions that are likely to be binocularly innervated. Indeed, almost all cells recorded electrophysiologically within the association clusters were strongly binocular, whereas between the clusters, many neurons were dominated by the contralateral eye. There is sufficient jitter in the retinotopic organization of area 17 for the discontinuous distribution of association cells to provide a continuous representation of the visual field. Cells in each association cluster in the rostral part of area 17 project divergently to innervate a zone extending up to 3 mm wide, anteroposteriorly, in the superficial layers of area 18. The receptive fields of cells at any point in area 18 are larger than for the corresponding point in area 17. Neurons recorded at two points in area 18, separated by a distance equal to the limit of anatomical divergence of the projection from area 17, have receptive fields that overlap by an amount similar to the region of visual field covered by the receptive fields of cells in a single association cluster in area 17 at a similar retinotopic position. Thus, area 18 receives a full and strongly binocular representation of the visual field not only from the lateral geniculate nucleus but also from area 17. The divergence of the area 17 to 18 projection compensates for the difference in receptive field size by ensuring that the receptive fields of each cluster of projecting neurons overlap fairly precisely those of the recipient neurons in area 18.

Amidines↗
PubMed1994

Postnatal development and plasticity of corticocortical projections from area 17 to area 18 in the cat's visual cortex.

We used retrogradely transported fluorescent tracers to study the development of projections from area 17 to area 18 in normal and monocularly deprived kittens. In newborn animals, cells in area 17 that were labeled from small, discrete injections in area 18 were concentrated around the retinotopically corresponding zone, but distributed with lower density over a very wide surrounding area. Hence, the total convergence and divergence of the projection were initially enormous, but they decreased dramatically, mainly during the first postnatal month, through elimination of the sparse, widespread distribution of projections. Injections of two different tracers close together in area 18 produced very few double-labeled cells in area 17 at any age, implying that most individual axons arborize over very small territories even at birth. In normal kittens the peak density of association cells in the upper layers, corrected for the overall expansion of the cortex, doubled over the first postnatal month and then declined gradually over the following several months, presumably because of continuing selection and elimination. As shown in previous work (Price and Blakemore, 1985a), area 17 to 18 cells in newborn kittens were distributed in two continuous bands in supragranular and infragranular layers. During normal maturation, elimination of projections results in the formation of distinct clusters; these lie preferentially in the upper layers above patches of ipsilateral eye input to layer 4 (Price et al., 1994). Monocular deprivation, which causes the terminal patches representing the deprived eye to become much smaller than normal, did not stop the normal decrease in overall convergence/divergence or the appearance of clusters of association cells, but the clusters were distinctly larger than normal in both hemispheres. Monocular deprivation also prevented the normal reduction in density of association cells within clusters after 1 month of age. Comparison with results from binocularly deprived animals, where clusters also form but association cell density is low, suggests that the size of clusters and the density of association cells retained depend on the overall level of cortical activity.

Aging↗
PubMed1994

[Concentrations of new quinolone agents in serum and prostate tissue].

Twenty five patients with benign prostate hypertrophy were administered ofloxacin (OFLX) simultaneously with norfloxacin (NFLX) in 6 patients, ciprofloxacin (CPFX) in 10, tosfloxacin (TFLX) in 5 and enoxacin (ENX) in 4 patients. The dose of these new quinolones was 100 mg (except 150 mg of TFLX). Their concentrations in the serum and the prostate tissue were measured by high performance liquid chromatography (HPLC). The serum concentration of OFLX was significantly higher than that of NFLX, CPFX, TFLX or ENX. The prostate tissue concentration of OFLX was significantly higher than that of CPFX or TFLX. The ratio of tissue versus serum concentration of each new quinolone agent was not significantly different. The high OFLX tissue concentration appeared to be caused by the high serum concentration.

4-Quinolones↗