Biomedical subjects

T Sakai

Publications and source records attributed to T Sakai.

At least 271 records · Page 15Linked to original sources

PubMed2000

Purification and characterization of thermostable pectate lyase with protopectinase activity from thermophilic Bacillus sp. TS 47.

A strain of thermophilic bacterium, Bacillus sp., with pectolytic activity has been isolated. It produced an extracellular endo-polygalacturonate trans-eliminase (PL, EC 4.2.2.1) when grown at 60 degrees C on a medium containing polygalacturonate (PGA). The PL was purified by hydrophobic, cation exchange, and size exclusion column chromatographies. The molecular mass of the enzyme was 50 kDa by SDS-PAGE. The isoelectric point of the enzyme was pH 5.3. The enzyme had a half-life of 13 and 1 h at 65 and 70 degrees C, respectively, and showed optimal activity around at 70 degrees C and pH 8.0. It had protopectinase activity, besides PL activity, on lemon protopectin and cotton fibers. The first 20 amino acids sequence of the enzyme had significant similarity with that of PL from methophilic Bacillus subtilis, with 50% identity.

Amino Acid Sequence↗

PubMed2000

Roles of renal dopamine and kallikrein-kinin systems in antihypertensive mechanisms of exercise in rats.

We have previously shown that both renal dopamine (DA) and kallikrein-kinin systems are activated by exercise in mild hypertensives. We aimed to confirm the effects of exercise on the renal DA system and the stimulatory effects of DA on the renal kallikrein-kinin system in rats. In experiment 1, 12 male Dahl salt-sensitive (DS) rats given a 4% salt diet were divided into two groups. Rats in the exercise group were forced to run at 8 m/min, 60 min/day, 5 days/week for 4 weeks. Daily urinary volume, urinary excretion of sodium, free DA, and kallikrein activity were measured weekly. Renal aromatic-L-amino-acid decarboxylase (AADC) activities were assayed at the end of the experiment. In experiment 2, 15 male Sprague-Dawley (SD) rats were randomly divided into 3 groups, a DA-5 (5 microg of DA/kg/min), a DA-10 (10 microg of DA/kg/min), and a control group. DA or vehicle was administered subcutaneously with an osmotic pump for 2 weeks. Daily urinary volume, urinary excretion of sodium, aldosterone, DA, and kallikrein activity were measured weekly. Plasma renin activity, aldosterone concentration, and renal kallikrein mRNA levels were determined at the end of the experiment. In experiment 1, urinary excretion of free DA and renal AADC activities in the exercise group were significantly higher than those in the non-exercise group at week 4. In experiment 2, renal kallikrein mRNA levels and urinary volume were significantly increased in the DA-10 group compared to the control group, although there were no differences in urinary kallikrein activities. Plasma aldosterone concentration was significantly decreased in the DA-10 group compared to that in the control group despite a lack of differences in plasma renin activities. In conclusion, exercise increased the urinary excretion of free DA, probably through increased renal AADC activity in DS rats. DA amplified renal kallikrein mRNA levels and decreased plasma aldosterone levels, probably through its suppression of aldosterone in the adrenal glands. Activation of the kallikrein-kinin system might be counteracted by post-transcriptional modification of aldosterone. These results suggest that exercise enhances renal dopamine production by activating renal AADC activity, which in turn stimulates the renal kallikrein-kinin system.

Aldosterone↗

PubMed2000

Four cases of lowered urethral pressure in canine ectopic ureter.

To evaluate the function of the constrictor urethrae of dogs that had urinary incontinence and were diagnosed as having ectopic ureter, the urethral pressure profile (UPP) was measured by means of a microchip catheter transducer. The UPPs (14.5 +/- 3.3 mmHg) of the four dogs suffering from ectopic ureter were much lower (p<0.001) than the UPPs of clinically healthy female dogs (35.3 +/- 5.7 mmHg). In the cases of ectopic ureter, it was shown that the UPP was lowered, and it was suggested that this would lead to the expression of urinary incontinence.

Animals↗

PubMed2000

Prevalence of Bartonella henselae, Bartonella clarridgeiae and the 16S rRNA gene types of Bartonella henselae among pet cats in Japan.

The authors investigated bacteriologically the prevalence of Bartonella infection among 690 pet cats derived from 10 private animal hospitals in six cities (Sapporo, Hokkaido Prefecture; Sendai, Miyagi Prefecture; Joetsu, Niigata Prefecture; Fujisawa, Kanagawa Prefecutre; Kyoto, Kyoto Prefecture; Sanda, Hyogo Prefecutre) and 4 counties (Mishima, Osaka Prefecture; Hikawa, Shimane Prefecture; Aira, Kagoshima Prefecture; Shimajiri, Okinawa Prefecture) located from the north to the south of Japan. Bartonella species were isolated from 7.2% (50/690) of all the cats examined. No Bartonella species were isolated from the cats in Sapporo or Sendai. The isolation rate varied from 2% in Joetsu and Sanda to 20% in Shimajiri. Bartonella clarridgeiae was isolated from two of 50 cats in Kyoto, three of 50 in Mishima and one of 50 in Shimajiri, but not in cats from the other cities or counties. Though the cats of Joetsu, Fujisawa, Kyoto, Sanda, Aira and Shimajiri were infected with either B. henselae or B. clarridgeiae, one of eight infected cats in Mishima was harboring both Bartonella species. Type I of 16S rRNA gene was the predominant type among the isolates of B. henselae, but only one isolate derived from Shimajiri was found to be of type II. Prevalence of B. clarridgeiae and the 16S rRNA gene type of B. henselae among cats in Japan was demonstrated for the first time in this investigation.

Animals↗

PubMed2000

Seroprevalence of Bartonella henselae and Toxoplasma gondii among healthy individuals in Thailand.

The seroprevalence of Bartonella henselae and Toxoplasma gondii among apparently healthy individuals, mainly blood donors, in Thailand was investigated by an indirect fluorescent antibody technique and by a latex agglutination test, respectively. Of 163 serum samples examined, 9 (5.5%) were found to be positive for B. henselae-IgG, 2 (1.2%) for B. henselae-IgM, and 5 (3.1%) for the T. gondii antibody. No significant difference was observed between male and female samples in the serological test with either B. henselae or T. gondii. The age of individuals with B. henselae-IgG was distributed from the 20s to the 70s, and B. henselae-IgM was found in the individuals of the 30s and 60s. The age of T. gondii positive samples ranged from the 20s to the 60s. In this study, the prevalence of B. henselae infection among healthy individuals in Thailand was serologically demonstrated for the first time.

Adolescent↗

PubMed2000

Double-chambered right ventricle in a dog.

A 32-month-old spayed female Pug was referred for an MRI study due to convulsions. The MRI examination indicated encephalitis. However, echocardiography and pathological examinations revealed that this case had a ventricular septal defect and double chambered right ventricle which is a rare congenital heart disease in the dog. An anomalous muscle bundle crossed the right ventricular outflow tract, dividing the right ventricle into 2 chambers.

Animals↗

PubMed2000

Effects of glucocorticoids on tumor necrosis factor alpha-dependent activation of nuclear factor kappaB and expression of the intercellular adhesion molecule 1 gene in osteoblast-like ROS17/2.8 cells.

Recently, we showed that tumor necrosis factor alpha (TNF-alpha) stimulates expression of the intercellular adhesion molecule 1 (ICAM-1) and interleukin-6 (IL-6) genes through activation of p65-p50 heterodimer nuclear factor KB (NF-kappaB) in rat osteoblast-like ROS17/2.8 cells. In the present study, we investigated effects of a synthetic glucocorticoid, dexamethasone (Dex), on TNF-alpha-dependent activation of NF-kappaB and expression of the ICAM-1 gene. ROS17/2.8 cells were pretreated with Dex for 6 h and then exposed to TNF-alpha. Electrophoretic mobility shift assay (EMSA) revealed that TNF-alpha-dependent activation of NF-kappaB was almost completely suppressed by Dex treatment. Increase in ICAM-1 messenger RNA (mRNA) level by TNF-alpha also was markedly suppressed by Dex. Western blot and immunocytochemical analyses showed that Dex attenuated the TNF-alpha-induced nuclear translocation of p65. Treatment with protein synthesis inhibitor cycloheximide (CHX) reversed the Dex effect, indicating that Dex requires de novo protein synthesis for its action. Northern blot analysis revealed that Dex increased IkappaB-alpha mRNA level synergistically with TNF-alpha, whereas it decreased p65 mRNA level. The p105 and IkappaB-beta mRNA levels were not altered by Dex. Consistent with the mRNA level, Dex increased the amount of IkappaB-alpha protein in the cytoplasm in either the presence or the absence of TNF-alpha. Considering a role of IkappaB to sequester NF-kappaB in the cytoplasm, it was suggested that an increase in IkappaB-alpha protein and the concomitant decrease in p65 synthesis account for the Dex-induced suppression of NF-kappaB activation in osteoblastic cells.

Animals↗

PubMed2000

Changes in trace element concentrations in hair of growing children.

Head hair concentrations of zinc, copper, manganese, alid iron from a total of 418 subjects (154 male and 264 female) aged between 6 mo and 20 yr were measured mainly with flameless atomic absorption spectrophotometry. Only zinc analysis of a part of the female samples (n = 140) were analyzed with inductively coupled plasmaatomic emission spectrometry. The two analytical methods showed close agreement. The mean concentration of copper and manganese were significantly higher in male subjects than in female subjects. The trace element concentrations in hair varied with the subject's age. Zinc concentration in hair decreased from 6 mo to 14 yr in the male subjects and decreased from 6 mo to 12 yr in the female subjects. Then, the concentrations increased gradually to 20 yr in the both sexes. Age-dependent variations of copper and manganese concentrations in hair showed similar trends to those of zinc. The results of this study suggest that a higher concentration in the diet of these trace elements may be required for growing children, especially in the period of adolescence.

Adolescent↗

PubMed2000

Rapid, sensitive and simple detection of candida deep mycosis by amplification of 18S ribosomal RNA gene; comparison with assay of serum beta-D-glucan level in clinical samples.

We evaluated the clinical usefulness of a polymerase chain reaction (PCR) assay amplifying the 18S ribosomal RNA gene of fungi for the diagnosis of deep candidiasis, compared with that of the beta-glucan test or Cand-Tec test. Thirty critically ill patients who had received prolonged care with intravenous hyperalimentation and endotracheal intubation in the intensive care unit and were suspected of having deep fungal infections were examined. Twenty-one were fungi positive in the PCR assay (70%). Among 24 samples in which the PCR assay, beta-glucan test and Cand-Tec test were performed simultaneously, 75% of the samples (18/24) were fungi positive in the PCR assay, whereas only 54% (13/24) had positive reactions in the beta-glucan test and 21% (5/24) in the Cand-Tec test. The results of the Cand-Tec test showed no relationship with those of the PCR or beta-glucan test. The lower limit of detection in the PCR assay was 4-5 CFU/ml of C. albicans in blood. No fungal organism was amplified from the serum of 20 healthy individuals. The results of the PCR assay and beta-glucan test showed a significant correlation in this study, but the PCR assay proved to be more sensitive than the beta-glucan test (p < 0.05), and to be more useful for the clinical diagnosis and monitoring of deep Candidiasis.

Candida↗

PubMed2000

The vasocontractive action of norepinephrine and serotonin in deep arterioles of rat cerebral gray matter.

To examine the direct effects of norepinephrine (NE) and serotonin (5-HT) on the contractility of arterioles in the gray matter of the rat cerebrum, we micro-perfused arterioles in vitro and observed the changes in luminal diameter under the stop-flow condition with constant intraluminal pressure. While the average diameter of the lumen of arterioles was 39.9 +/- 9.7 microm (n=7) in Hepes-buffered saline, the average in 10(-7) M NE in the extraluminal solution changed into smaller in saline by 21.1 +/- 5.4% (n=7). The contractile effect of NE shows a dose-dependent curve between the 10(-7) and 10(-5) M. The contractile response to 10(-6) M NE was significantly reduced by yohinbin, an alpha2 blocker. 10(-6) M NE applied to the lumen also caused contraction of arterioles by 12.4 +/- 5.3% in diameter (n=5). 5-HT at 10(-7) M in the extraluminal solution caused contraction of arterioles by 10.9 +/- 4.4% in diameter (n=7). 5-HT in the extraluminal solution caused contraction of arterioles in a dose dependent manner between 10(-10) and 10(-6) M. The contractile effect of 5-HT at 10(-6) M was strongly reduced by 10(-6) M ketanserin, a 5-HT2 receptor antagonist. 5-HT applied to the lumen had no effect at all (n=6), however NE applied to the lumen caused contraction. These results strongly suggest that 5-HT plays a significant role in arteriolar contractility only from the cerebrospinal fluid (CSF) side, while NE is an important regulator of arteriolar contractility from both the CSF and blood circulation sides.

Adrenergic alpha-Antagonists↗

PubMed2000

Identification of a novel calcitonin-response element in the promoter of the human p21WAF1/CIP1 gene.

The cyclin-dependent kinase inhibitor p21/WAF1/CIP1 is induced in many cell types in response to a variety of extracellular signals and causes cell cycle arrest in both the G1 and G2/M phases of the cell cycle. We reported previously that calcitonin (CT) receptor (CTR)-mediated growth inhibition of HEK-293 cells stably transfected with the human CTR is accompanied by a rapid and sustained induction of p21 and cell cycle arrest in G2. In the present study we have shown that CT stimulates transcription from a p21 promoter-luciferase construct. Using deletion and mutation analysis of the p21 promoter we have demonstrated that transcriptional activation of p21 by CT is p53-independent and is mediated through specific activation of Sp1-binding sites in a region of the promoter between -82 and -69, relative to the transcription start site. CTR-mediated transcriptional activation of p21 was specific for the insert-negative isoform of the human CTR. Butyrate, which was shown previously to activate the same Sp1 site, synergised with CT to increase further p21 promoter activity. These results provide the first demonstration that CTR can induce gene transcription through the constitutively expressed transcription factor Sp1, and define a mechanism of cell growth suppression that may have implications for other members of the seven-transmembrane domain G protein-coupled receptor superfamily.

Butyrates↗

PubMed2000

Collaborative work to evaluate toxicity on male reproductive organs by repeated dose studies in rats--overview of the studies.

The National Institute of Health Sciences and 28 member companies of the Japan Pharmaceutical Manufacturers Association (JPMA) have conducted a validation study intended to examine whether or not lesions in the male reproductive organs noted in 4-week treatment studies can also be detected after 2-week treatment. In this study, lesions in the male reproductive organs after 2-week treatment were, therefore, compared with those after 4-week treatment. A total of 24 test substances was evaluated, these being nucleic acid modulators, cell division inhibitors, central hormonal modulators, hormonal drugs and their antagonists, other drugs and general chemicals. Among these substances, theophylline did not cause any appreciable lesions in the male reproductive organs even after 4-week treatment in the preliminary studies. With busulfan, data reported in the literature was not reproduced in the preliminary study and all animals died. Therefore, detailed examinations were not conducted for busulfan and theophylline. The remaining 22 test substances, when given to animals for 2 weeks at doses equal to or higher than for 4-week treatment, caused lesions similar to those noted after 4 weeks. It is evident from these findings that effects of pharmaceuticals on the male reproductive organs can be detected in most cases with 2-week treatment.

Animals↗

PubMed2000

Collaborative work to evaluate toxicity on male reproductive organs by repeated dose studies in rats 20). Testicular toxicity of nitrofurazone after 2 and 4 weeks.

Nitrofurazone (NF) has been previously demonstrated to induce testicular toxicity with 4 weeks of oral administration in rats. In the present study, rats were administered NF to assess whether testicular toxicity becomes evident with a 2-week administration period. Male Sprague-Dawley rats were administered oral doses of NF at 50 mg/kg for 2 or 4 weeks. Another group was administered NF at 100 mg/kg for 2 weeks. The control animals received the vehicle (0.5% methylcellulose) for 4 weeks. Organ weights of the testis and epididymis were significantly decreased in all NF-administered animals, and seminiferous tubules were severely atrophied, due to a total absence of spermatids and degeneration and desquamation of spermatocytes. In the epididymis, decreased numbers of spermatozoa were evident in the ducts. In rats that were administered NF at 50 mg/kg, the changes in the epididymis in the 2-week group were less prominent than those in the 4-week group. In the testis, however, the changes were similar in both groups. Thus it was demonstrated that NF-induced testicular toxicity comparable to that observed after 4 weeks of administration is also detectable after 2 weeks.

Administration, Oral↗

PubMed2000

Slowly progressive insulin-dependent diabetes mellitus in an elderly patient with Graves' disease.

We report a case of slowly progressive insulin-dependent diabetes mellitus in an elderly patient with Graves' disease. A 69-year-old man presented with apathetic thyrotoxicosis and weight loss. Laboratory findings indicated insulin-dependent diabetes mellitus (IDDM) with Graves' disease. Human leukocyte antigens DR4 and DR9, which are recognized as markers for IDDM with autoimmune thyroid disease, were detected. The clinical course of the IDDM was compatible with the slowly progressive type. Onset of this disease during old age is rare, and such cases should be analyzed with a thyroid function test because the symptom of thyrotoxicosis may be masked in the elderly.

Age Factors↗

PubMed2000

Relationship between suicide and holidays.

Employing the vital statistics from January 1, 1979 to December 31, 1994 in Hokkaido Prefecture, Japan, we investigated the relationship between suicide (ICD 9 code, El15) and days of the week. In one day 1.97 males and 0.98 females committed suicide on average. On Saturdays the number of suicides per day was the smallest. On Mondays it was the highest. When the days were classified into (1) a holiday, (2) the day before a holiday, (3) the day after a holiday (4) the day both before and after a holiday and (5) others, the rate of suicide was the lowest in the days before a holiday. In the days after a holiday, however, the rate was the highest. The same tendency was also noted when the subjects were classified into several subgroups from the viewpoint of ages, seasons or calendar years. The time relation of holidays seemed to have something to do with the intention to commit suicide.

Chi-Square Distribution↗

PubMed2000

Biomarkers of lead exposure.

Biomarkers of exposure, effect, and susceptibility are reviewed in relation to lead exposure. Of the biomarkers of lead exposure, blood lead (Pb-B), mainly red cell lead, is a representative of soft tissue lead, and most widely used as measures of body burden and absorbed (internal) doses of lead. Urine lead (Pb-U) as well as plasma lead (Pb-P) increases exponentially with increasing Pb-B under a steady-state situation and is a reflection of recent exposure. The amount of lead in plasma and urine (MPb-P and MPb-U) after administration of a chelating agent (e.g. CaEDTA) can be useful for biomarkers of internal exposure of lead, reflecting the mobilizable pool of lead which consists of mainly blood and soft tissue lead with only a small fraction derived from bones. The critical effects in bone marrow arise mainly from the interaction of lead with some enzymatic process responsible for heme synthesis. The effects can be used for the biomarkers of effects. They are the inhibition of delta-aminolevulinic acid dehydratase (ALAD) and the variation in some metabolite concentrations (e.g. delta-aminolevulinic acid in urine (ALA-U), blood (ALA-B) or plasma (ALA-P), coproporphyrin in urine (CP), zinc protoporphyrin (ZP) in blood). The activities of pyrimidine nucleotidase (P5'N) and nicotinamide adenine dinucleotide synthetase (NADS) in blood are also decreased in lead exposure, and nucleotide contents in blood is altered in lead exposure. These effects of lead on human can be also useful biomarkers of effect. The differences in levels of heme precursors between two types of ALAD genotypes might be attributable to those in the affinity of different ALAD isozymes to lead. ALAD1 homozygotes have higher levels of ZP and ALA in comparison with ALAD2 carriers at the high lead exposure, suggesting that ALAD1 homozygotes might be more susceptible for disturbance in heme biosynthesis by lead than ALAD2 carriers.

Biomarkers↗

PubMed2000

Decrease of glucose utilization rate in the spinal cord of experimental 2,5-hexanedione poisoning rats: application of microdetermination technique.

To examine the effects of 2,5-hexanedione (HD) on the glucose metabolism in the spinal cord, glucose utilization rate (GUR) and distribution volume of glucose (DV) were measured in the white matter and anterior horn of the spinal cord in 8 rats exposed to HD for 4 weeks and in 10 control rats. The GUR and DV were determined by the quantitative microdetermination method using non-tracer 2-deoxyglucose based on the three-compartments model of Sokoloff. GURs in the white matter and anterior horn and DV in the anterior horn in the HD-exposed rats were significantly lower than those in the control rats. In the multiple regression analysis, GUR in the white matter of HD-exposed rats was significantly related to blood HD concentration. It is suggested that the decrease of GUR in the white matter is a major effect of HD in the spinal cord.

Administration, Oral↗

PubMed2000

Alteration of glucose metabolism in the spinal cord of experimental lead poisoning rats: microdetermination of glucose utilization rate and distribution volume.

To examine the effects of lead on glucose metabolism in the spinal cord, glucose utilization rate (GUR) and distribution volume of glucose (DV) in the anterior horn and white matter were determined in 9 rats exposed to lead for 4 weeks and 10 control rats. The GUR and DV were determined by the quantitative microdetermination method using non-tracer amount of 2-deoxyglucose based on the three-compartments model of Sokoloff. The GUR and DV in the anterior horn in the lead-exposed rats were significantly lower than those in the controls. It is thus suggested that glucose metabolism, as measured by the GUR and DV, in the anterior horn is inhibited by lead; the anterior horn cells seem sensitive to lead neurotoxicity.

Animals↗