Biomedical subjects

N Kato

Publications and source records attributed to N Kato.

At least 289 records · Page 16Linked to original sources

PubMed1999

Use of PCR and sodium dodecyl sulfate-polyacrylamide gel electrophoresis techniques for differentiation of Prevotella intermedia sensu stricto and Prevotella nigrescens.

Primers were designed from 16S rRNA sequences of Prevotella intermedia sensu stricto and Prevotella nigrescens and were used to discriminate these two species by PCR. The results were compared with those from the PCR technique using primers designed from arbitrarily primed PCR products by Guillot and Mouton (E. Guillot and C. Mouton, J. Clin. Microbiol. 35:1876-1882, 1997). The specificities of both assays were studied by using P. intermedia ATCC 25611, P. nigrescens ATCC 33563, 174 clinical isolates of P. intermedia sensu lato, and 59 reference strains and 58 clinical isolates of other Prevotella species and/or common oral flora. In addition, the usefulness and reliability of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) in the differentiation of the two species were examined by comparing the results with those from PCR assays. The controversial lipase test for distinguishing these species was also carried out. Unambiguous differentiation was made by both PCR assays, and the results matched each other. The SDS-PAGE assay was found to misidentify a few strains tested, compared with the results of PCR assays. The lipase test was positive for both species, including the reference strains of P. intermedia and P. nigrescens. We conclude that both PCR assays are simple, rapid, reliable, and specific methods which could be used in clinical studies and that the lipase test is not valuable in the differentiation. The reliable discrimination of the two species by SDS-PAGE is questionable.

Bacterial Typing Techniques↗

PubMed1999

Identification of and hydrogen peroxide production by fecal and vaginal lactobacilli isolated from Japanese women and newborn infants.

We identified Lactobacillus isolates from Japanese women and newborn infants by a DNA-DNA hybridization method. The predominating lactobacilli were Lactobacillus crispatus and Lactobacillus gasseri in the women's vaginas and the newborns' intestines and L. gasseri and Lactobacillus fermentum in the women's intestines. All L. crispatus strains were exclusively strong H2O2 producers.

DNA, Bacterial↗

PubMed1999

Structure of cag pathogenicity island in Japanese Helicobacter pylori isolates.

BACKGROUND: cag pathogenicity island (PAI) is reported to be a major virulence factor of Helicobacter pylori. AIM: To characterise cagA and the cag PAI in Japanese H pylori strains. METHODS: H pylori isolates from Japanese patients were evaluated for CagA by immunoblot, for cagA transcription by northern blot, and for cagA and 13 other cag PAI genes by Southern blot. cagA negative strains from Western countries were also studied. Induction of interleukin-8 secretion from gastric epithelial cells was also investigated. RESULTS: All Japanese strains retained cagA. Fifty nine of 63 (94%) strains had all the cag PAI genes. In the remaining four, cag PAI was partially deleted, lacking cagA transcripts and not producing CagA protein. Details of the PAI of these strains were checked; three lacked cagB to cagQ (cagI) and continuously cagS to cag13 (cagII), and the remaining one lacked cagB to cag8. Western cagA negative strains completely lacked cag PAI including cagA. Nucleotide sequence analysis in one strain in which the cag PAI was partially deleted showed that the partial deletion contained 25 kb of cag PAI and the cagA promoter. Interleukin-8 induction was lower with the cag PAI partial deletion strains than with the intact ones. All Japanese cag PAI deleted strains were derived from patients with non-ulcer dyspepsia, whereas 41 of 59 (70%) CagA-producing strains were from patients with peptic ulcers or gastric cancer (p<0.05). CONCLUSIONS: Most Japanese H pylori strains had the intact cag PAI. However, some lacked most of the cag PAI in spite of the presence of cagA. Thus the presence of the cagA gene is not an invariable marker of cag PAI related virulence in Japanese strains.

Adult↗

PubMed1999

Action potential-induced dendritic calcium dynamics correlated with synaptic plasticity in developing hippocampal pyramidal cells.

In hippocampal CA1 pyramidal cells, intracellular calcium increases are required for induction of long-term potentiation (LTP), an activity-dependent synaptic plasticity. LTP is known to develop in magnitude during the second and third postnatal weeks in the rats. Little is known, however, about development of intracellular calcium dynamics during the same postnatal weeks. We investigated postnatal development of intracellular calcium dynamics in the proximal apical dendrites of CA1 pyramidal cells by whole cell patch-clamp recordings and calcium imaging with the Ca(2+) indicator fura-2. Dendritic calcium increases induced by intrasomatically evoked action potentials were slight during the first postnatal week but gradually became robust 3 to 6-fold during the second and third postnatal weeks. These calcium increases were blocked by application of 250 microM CdCl(2), a nonspecific blocker for high-threshold voltage-dependent calcium channels (VDCCs). Under the voltage-clamp condition, both calcium currents and dendritic calcium accumulations induced by depolarization were larger at the late developmental stage (P15-18) than the early stage (P4-7), indicating developmental enhancement of calcium influx mediated by high-threshold VDCCs. Moreover, theta-burst stimulation (TBS), a protocol for LTP induction, induced large intracellular calcium increases at the late developmental stage, in synchrony with maturation of TBS-induced LTP. These results suggest that developmental enhancement of intracellular calcium increases induced by action potentials may underlie maturation of calcium-dependent functions such as synaptic plasticity in hippocampal neurons.

Action Potentials↗

PubMed1999

Relationship of energy metabolism detected by 31P-MRS in the human brain with mental fatigue.

To search for a possible relationship between brain energy metabolism and mental fatiguability, 10 normal volunteers were examined by 31P-MRS (phosphorus-31 magnetic resonance spectroscopy) in the occipital cortex during photic stimulation (PS), and Uchida-Kraepelin test (UKT), a standardized serial calculation task, was used for measurement of intraindividual characteristics of mental fatigue in these subjects. More decrease of phosphocreatine measured by 31P-MRS during the PS was significantly associated with more effects of rest assessed by UKT (r = -0.86, p <0.005). More decrease in pH after PS was associated with steeper decline of performance (r = 0.78, p <0.01). These findings suggest that characteristics of brain energy metabolism in an individual may relate to intrinsic patterns of mental fatigability.

Adult↗

PubMed1999

Lack of evidence for association between the endothelial nitric oxide synthase gene and hypertension.

Significant association between a Glu298Asp polymorphism of the endothelial nitric oxide synthase (eNOS) gene and essential hypertension was recently reported in Japanese populations, with the 298Asp variant showing a higher prevalence in hypertensive patients (10.3% to 12.0%) than in normotensive subjects (5.0% to 5.8%). In contrast, another study demonstrated that the 298Glu variant was significantly associated with hypertension in a Caucasian population. We therefore undertook an extensive association study in Japanese to resolve these contradictory claims. A total of 1165 individuals were selected from clinic outpatients and hospital staff in a single institution. The relevance of the Glu298Asp polymorphism to hypertension in this population was tested in 2 ways. First, a case-control study was conducted in 549 hypertensive and 513 normotensive subjects within the study population, with the chi2 statistic used to test the significance of an association between eNOS genotype and the presence of hypertension. Second, an ANOVA was used to test the significance of an association between eNOS genotype and the level of blood pressure within the entire population except for 167 hypertensive subjects who had been under treatment for hypertension. No significant association was observed in either of the statistics tested. Allele frequencies of 298Asp were concordant across the panels: 8.4% in hypertensive subjects, 8. 2% in normotensive subjects, and 7.9% and 9.5% in 2 additional sample populations used as reference panels. Taken together, our results do not support the previous observation that the molecular variant of the eNOS gene may confer principal susceptibility for essential hypertension but rather suggest the existence of sampling variation.

Adult↗

PubMed1999

Susceptibility of lamivudine-resistant hepatitis B virus to other reverse transcriptase inhibitors.

The emergence of resistant hepatitis B virus (HBV), with mutations in the YMDD motif of the polymerase gene after treatment with lamivudine, is becoming an important clinical problem. In this study, susceptibility of wild-type and lamivudine-resistant HBV M552I, M552V, and L528M/M552V mutants to other reverse transcriptase inhibitors was investigated by transient transfection of full-length HBV DNA into human hepatoma cells. HBV DNA replication was monitored by Southern blot hybridization, which showed the presence of a single-stranded band (representative of the HBV replicative intermediates) in the drug-free, wild-type HBV-transfected cells. This band was diminished in the samples of wild-type HBV DNA treated with either lamivudine, adefovir, or lobucavir. The band intensities from the lamivudine-resistant mutants were not decreased by treatment with lamivudine, but were decreased by the treatments with adefovir or lobucavir. In contrast, penciclovir and nevirapine did not diminish the intensity of the single-stranded band of wild-type HBV or the lamivudine-resistant mutants. These results demonstrate that lamivudine-resistant HBV is susceptible to adefovir and lobucavir. Lamivudine-resistant HBV should be treated with adefovir or lobucavir, and combination therapy with lamivudine and adefovir/lobucavir may prevent the emergence of lamivudine-resistant HBV.

Acyclovir↗

PubMed1999

Blood flow velocity in the middle cerebral artery response to tourniquet release.

This study was undertaken to examine the effects of tourniquet release on middle cerebral arterial (MCA) blood flow velocity in patients undergoing general anaesthesia for orthopaedic surgery. In 30 patients (ASA physical status 1 or 2) undergoing orthopaedic procedures on the upper (Group U, n = 15) and lower (Group L, n = 15) extremities, MCA blood flow velocity was measured before and after tourniquet deflation using transcranial Doppler sonography. The MCA blood flow velocity increased after release of the intraoperative tourniquet and remained elevated for two minutes in Group U (P < 0.05) and for four minutes in Group L (P < 0.05). The increase in MCA blood flow velocity was greater in Group L than in Group U (P < 0.05). A positive linear correlation between MCA blood flow velocity and PETCO2 after tourniquet deflation was observed in both groups (P < 0.001).

Adult↗

PubMed1999

Muscle hypertrophy in rats fed on a buckwheat protein extract.

Growing rats were examined for the influence of a buckwheat protein diet on muscle weight and protein. In experiment 1, the rats were fed on a diet containing either casein or a buckwheat protein extract (BWPE) as the protein source (10%, 20% or 30%) for 5 wk. The relative weights (g per kg of body wt) of the gastrocnemius, plantaris and soleus muscles were higher in the BWPE-fed animals than in the casein-fed ones, but were unaffected by the dietary level of protein. These differences were not associated with growth. In experiment 2, the rats were fed on either a casein or BWPE diet at the 20% protein level for 5 wk. BWPE intake significantly elevated the gastrocnemius muscle weight, carcass protein and water, and reduced carcass fat. These results demonstrate that BWPE consumption causes muscle hypertrophy, elevates carcass protein and water, and reduces body fat.

Amino Acids↗

PubMed1999

Hypertriglyceridemia in rats induced by consumption of a food-derived carcinogen, 2-amino-1-methyl-phenylimidazo[4,5b]pyridine (PhIP).

2-Amino-1-methyl-phenylimidazo[4,5b]pyridine (PhIP), the most abundant mutagenic heterocyclic amine produced in cooked meat and fish, is known to be a carcinogen for rats and mice. This study provides the first evidence for hypertriglyceridemia in rats exposed to PhIP, suggesting its potential risk to induce not only carcinogenesis, but also atherosclerosis, and highlighting the potential importance of PhIP for humans.

Animals↗

PubMed1999

Consumption of a buckwheat protein extract retards 7,12-dimethylbenz[alpha]anthracene-induced mammary carcinogenesis in rats.

Female rats were examined for the effects of feeding buckwheat protein extract (BWPE) on the development of mammary tumor caused by administration of 7,12-dimethylbenz[alpha]anthracene. The percentage of rats with palpable mammary tumors and serum estradiol were lower in the BWPE-fed animals than the casein-fed ones, implying that BWPE intake retarded the mammary carcinogenesis by lowering serum estradiol.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1999

A new carboxylesterase from Brevibacterium linens IFO 12171 responsible for the conversion of 1,4-butanediol diacrylate to 4-hydroxybutyl acrylate: purification, characterization, gene cloning, and gene expression in Escherichia coli.

A carboxylesterase that is responsible for conversion of 1,4-butanediol diacrylate (BDA) to 4-hydroxybutyl acrylate (4HBA) was found in Brevibacterium lines IFO 12171, and purified to homogeneity. The purified enzyme was active toward a variety of diesters of ethylene glycol, 1,4-butanediol, and 1,6-hexanediol. The K(m) and kcat of the enzyme for BDA were 3.04 mM and 203,000 s-1, respectively. The reaction with the purified enzyme gave 98 mM 4HBA from 100 mM BDA for 60 min. The enzyme gene was cloned from the chromosomal DNA of the bacterium. The open reading frame encoding the enzyme was 1176 bp long, corresponding to a protein of 393 amino acid residues (molecular mass = 42,569 Da). The deduced amino acid sequence contained the tetra peptide motif sequence, STTK, and the serine residue was confirmed to be the catalytic center of BDA esterase by site-directed mutagenesis for several amino acid residues. The gene was expressed in Escherichia coli under the control of the lac promoter, and the gene product (a fusion protein with 6 amino acid residues from beta-galactosidase) showed the same catalytic properties as the enzyme from the parent strain.

Acrylates↗

PubMed1999

Elevated body fat in rats by the dietary nitric oxide synthase inhibitor, L-N omega nitroarginine.

The influence of the dietary nitric oxide (NO) synthase inhibitor, L-N omega nitroarginine (L-NNA) on body fat was examined in rats. In experiment 1, all rats were fed with the same amount of diet with or without 0.02% L-NNA for 8 wk. L-NNA intake caused elevations in serum triglyceride and body fat, and reduction in serum nitrate (a metabolite of nitric oxide). The activity of hepatic carnitine palmitoyltransferase was reduced by L-NNA. In experiment 2, rats were fed for 8 wk with the same amount of diets with or without 0.02% L-NNA supplemented or not with 4% L-arginine. The elevation in body fat, and the reductions in serum nitrate and in the activity of hepatic carnitine palmitoyltransferase by L-NNA were all suppressed by supplemental L-arginine. The results suggest that lower NO generation elevated not only serum triglyceride, but also body fat by reduced fatty acid oxidation.

Adipose Tissue↗

PubMed1999

Lack of sex-specific effects on the association between angiotensin-converting enzyme gene polymorphism and hypertension in Japanese.

Although several studies of molecular genetics have investigated the relevance of the ACE gene to essential hypertension, the relationship remains controversial. Some studies have recently implicated sex-specificity of this candidate gene in hypertension genetics; that is, significant linkage and association were observed in men but not in women in Caucasian populations. In particular, a male-specific association was seen between the ACE insertion/deletion (I/D) polymorphism and hypertension. This could partially explain the negative results for such an association in a number of previous studies in which the subjects were not stratified according to sex. To determine whether the ACE I/D polymorphism is related to essential hypertension in Japanese subjects, we conducted a case-control study in 701 men (387 hypertensive and 314 normotensive subjects) and 542 women (324 hypertensive and 218 normotensive subjects). The genotype distribution (or allele frequencies) and hypertension status were compared between the case and control subjects with the chi2 test statistic. We found no significant association between I/D genotype and hypertension when men and women were analyzed separately or together. The results did not change appreciably when the case group of each sex was subdivided according to more stringent criteria. The odds ratio for D-allele vs. I-allele was estimated to be 0.90 (95% CI; 0.73-1.12) in men and 0.90 (95% CI; 0.70-1.16) in women. Taken together, our data do not support the existence of a sex-specific association between the ACE I/D polymorphism and essential hypertension in the Japanese population.

Aged↗

PubMed1999

[Clinical studies on inverted papilloma of the urinary tract].

BACKGROUND: Inverted papilloma of the urinary tract is believed to be a benign neoplasm based on its histologic morphology and clinical behavior. In recent years, however, several investigators have warned against too optimistic an approach, emphasizing the possibility of malignant cellular transformation within the lesion, or its eventual association with other urothelial tumors such as transitional cell carcinoma or carcinoma in situ. We here report on 35 clinicopathologically diagnosed cases of inverted papilloma, and present the clinical significance attributed to these lesions in view of the current literature. PATIENTS AND METHODS: From 1976 to 1997, 35 cases of inverted papilloma of the urinary tract were treated at our hospital. This report presents the clinical features of these cases, the results of prognosis research, an investigation of the cases in which inverted papilloma and transitional cell carcinoma were found to co-exist, and a discussion of the recurrent cases of inverted papilloma found in previous literature. RESULTS: The patients ranged from 24 to 77 years of age, with a mean of 54 years, and included 4 women and 31 men. The most frequently occurring symptom was grosshematuria, and more than 90% of the 35 cases occurred in the bladder. In 2 of the 35 cases, transitional cell carcinoma coexisted with the inverted papilloma, at a different location in the bladder in one case and within the same neoplasm in the ureter in the other case. Clinical courses after treatment were followed in 29 of the 35 cases, with a follow-up period of from 8 months to 19 years (mean follow-up, 5 years and 4 months). Of these 29 cases, 2 showed recurrence, one at 16 and one at 30 months after the initial resection. Many previous reports show that the association of inverted papilloma and transitional cell carcinoma is stronger in the upper urinary tract and recurrence of inverted papilloma almost always happens with 2 years. CONCLUSION: This study suggests that some cases of urinary inverted papilloma show recurrence or malignant potential. Our results indicate that all cases of urinary inverted papilloma should be treated and followed as cases of low-grade transitional cell carcinomas. Consequently, all cases must be followed for two years or more after the initial operation.

Adult↗

PubMed1999

[Evaluation of clinical usefulness of MR urography].

BACKGROUND: MR urography (MRU) is an image diagnostic method which provides us with the image of urinary retention under non-invasive procedures. This time, MRU was conducted in the patients who were suspected to have urinary passage disorder, and its clinical usefulness was compared with that of drip infusion pyelography (DIP) or retrograde pyelography (RP). METHODS: The study was conducted in 65 patients who were suspected to have obstructive uropathy based on the ultrasonographic findings. MRU was conducted by means of fast SE method to obtain heavy T2-weighted image. The urogram was reconstructed by means of MIP (maximum intensity projection) method. As imaging examinations, MRU, DIP and RP were conducted respectively in 65, 47 and 27 patients. Evaluation of clinical usefulness of MRU and its indications were conducted with respect to (1) the degree of urinary retention which is identifiable by MRU by (2) comparing performance of MRU and that of other image diagnostic methods based on the scores given to MRU and other methods according to the following scale: Urinary tract is not identifiable 0 point Urinary tract is slightly identifiable 1 point The obstructive region is almost clearly identifiable 2 points The lesion causative for obstruction is identifiable 3 points. RESULTS: 1) Mild urinary retention for which overall image of urinary tract was barely identifiable by DIP was identifiable by MRU. 2) In the comparison between DIP and MRU, 24 patients whose urinary tracts were totally unidentifiable by DIP was given was 2.4 points in the average for the identifiability of urinary retention by MRU. Conversely, only poor images were attainable by MRU in the patients whose urinary flow was clearly seen in DIP. The patients whose urinary flow was clearly seen in RP was give 1.9 points in the average for the identifiability of urinary retention by MRU, indicating that relatively poor images were attainable by MRU in those patients. CONCLUSION: Mild urinary retention for which overall image of urinary tract was barely identifiable by DIP was identifiable by MRU. Therefore, it is suggested that MRU is more useful in the case that only poor images were attainable by DIP. MRU is not the one which can replace RP including urinary cytodiagnosis but is useful to identify the location of the urinary tract tumor which is unidentifiable by RP or to monitor the progress of the urinary obstruction caused by benign diseases.

Adolescent↗

PubMed1999

[Treatments for post-pneumonectomy pyothorax without broncho-pleural fistula: irrigation of the post-pneumonectomy space].

Between January 1986 and December 1997 pneumonectomy was performed in 58 patients. Of the 58 patients, four had pyothorax without broncho-pleural fistula. Four patients underwent chest tube drainage and irrigation of the post-pneumonectomy space, and one of which died of lung cancer during treatment for pyothorax. Two had no evidence of recurrent infection, and one had a chest wall fistula after about one year and a fistulectomy was performed. These observations suggest that draining and irrigating of the post-pneumonectomy space are effective and non-invasive methods for treating post-pneumonectomy pyothorax without broncho-pleural fistula. However we were not able to investigate specific methods, fluid types, or irrigation time frames.

Empyema, Pleural↗

PubMed1999

[Evaluation of child-rearing environmental factors that affect the occurrence of sudden infant death syndrome: interview conducted by public health nurses].

PURPOSE: We examined the child-rearing environmental factors that affect the occurrence of sudden infant death syndrome (SIDS) by using a nation-wide survey. METHOD: Infants who died due to SIDS between January 1996 and June 1997 in Japan were identified from death certificates. Controls of the same sex, birthplace, and birth months as the corresponding SIDS were chosen from birth certificates. Interviews of both cases and controls were undergone in January and February 1998 by public health nurses. RESULTS: The following Child-rearing factors exhibited a significant relationship with the occurrence of SIDS: 1. Concerning the sleeping position, the prone position was associated with increased risk compared to the supine position, with an odds ratio of 3.02 (95% c.i. 2.07-4.65). 2. Regarding the feeding method, artificial feeding only demonstrated a higher risk than breast feeding only, with an odds ratio of 4.92 (95% c.i. 2.78-9.63). 3. With regard to smoking, infants with both parents who smoked exhibited a higher risk than infants where neither parents smoked, with an odds ratio of 3.50 (95% c.i. 1.74-8.32).

Child Rearing↗