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Biomedical subjects

H Tamura

Publications and source records attributed to H Tamura.

At least 127 records · Page 7Linked to original sources
PubMed1998

Effects of gonadal hormones on the zonal expression of rat hepatic phenol sulfotransferases.

Estradiol benzoate (EB) and testosterone propionate (TP) were administered to male and female Wistar rats, and their effects on the zonal expression of hepatic phenol sulfotransferase (P-ST) activities were determined at pH 5.5 and 7.4. Cytosolic fractions from periportal (PP) and perivenous (PV) hepatocytes were prepared by the dual-digitonin-pulse perfusion technique. In control rats, P-ST activities assayed at pH 5.5 and 7.4 were higher in males than in females, and were higher in the PV fraction than in the PP fraction in both sexes. P-ST activities were increased by the administration of TP in the PP and PV fractions of females, whereas the same treatment diminished the enzyme activities in both fractions of the males. EB administration gave reduced P-ST activity at pH 5.5 of both fractions, irrespective of sex, but not a marked difference at pH 7.4. Chromatofocusing of PP and PV fractions revealed the presence of P-ST isoforms eluted at approx. pH 8.0 (peak 1), 7.5 (peak 2), 7.0 (peak 3) and 6.0 (peak 4). In male rats, peak 3, which showed high enzyme activity at pH 5.5 in the PP and PV fractions, was markedly decreased by EB treatment, whereas in females, peak 3 was present only in the PV fraction and was not affected by EB administration. TP treatment did not show remarkable changes in P-ST peaks in the males, while peaks 2 and 3 were increased in the females. Immunoblot analysis revealed the presence of multiple P-ST isoforms which showed different immunoreactivity and electrochemical properties.

Animals↗
PubMed1998

Pinealectomy of melatonin implantation does not affect prolactin surge or luteal function in pseudopregnant rats.

The effects of melatonin on twice daily surges in PRL and luteal function were studied in pseudopregnant (PSP) rats. Cyclic rats received pinealectomy or sham operation under pentobarbital anesthesia on diestrus 1. Pinealectomized rats immediately received a melatonin capsule (the PINX+Mel group) or a blank capsule (the PINX group), and sham group of rats received a blank capsule (the control group). After operation, all rats were maintained under the same photoperiod conditions (14L: 10D), and estrous cyclicity was examined. At the 8th estrous cycle after operation, PSP was induced by mechanical stimulation of the uterine cervix. The last day on which the rat exhibited the estrous smear was designated as day 1 of PSP. Blood samples were obtained by jugular venipuncture under light ether anesthesia between 1200 and 1300 h on days 1, 3, 5, 7, 9 and 11, and between 0000 and 0100 h on day 13 of PSP. All rats were decapitated between 1200 and 1300 h on day 13 of PSP, and trunk blood was collected. A silicon catheter was inserted into the right jugular vein under ether anesthesia on day 4 of PSP. Blood samplings were performed every 2 h between 1000 h on day 5 and 1000 h on day 6 of PSP. Serum concentrations of melatonin, PRL and progesterone were measured by radioimmunoassay. Pinealectomy or melatonin installation did not disturb the estrous cyclicity or the induction of PSP. There were no differences among the three groups of rats during PSP in the pattern or serum PRL concentrations, and there were no significant differences among these three groups in the serum progesterone concentration or weight of the corpus luteum. The present results indicated that the continuously high or low melatonin in the physiological range did not affect the rhythm or strength of PRL surges or luteal function in PSP rats.

Animals↗
PubMed1998

Eradication of Helicobacter pylori restores elevation of serum gastrin concentrations in patients with end-stage renal disease.

In order to explore the role of Helicobacter pylori (H. pylori) infection in hypergastrinemia in patients on dialysis, the changes in serum gastrin concentration were examined before and after eradication treatment for H. pylori. Twenty-seven patients on dialysis were treated for the eradication of H. pylori. Fasting serum gastrin concentrations were measured by a radioimmunoassay which detects gastrin 17. Ammonia and pH levels of the gastric juice were also measured. The serum gastrin concentrations were significantly decreased following eradication of H. pylori, and the mean value reached the normal range. The restoration of hypergastrinemia was associated with marked reductions of gastric juice ammonia and pH levels. In contrast, patients in whom H. pylori was not eradicated showed no changes in these parameters. In conclusion, the elevation of the fasting serum gastrin 17 concentration seen in dialysis patients appeared to be attributable to H. pylori infection in the stomach.

Ammonia↗
PubMed1998

Functional MR imaging of cortical activation of the cerebral hemispheres during motor tasks.

PURPOSE: We used functional MR imaging to evaluate cortical activation in the precentral, central, and postcentral regions of the contralateral and ipsilateral cerebral hemispheres during left- and right-handed motor tasks. METHODS: Ten healthy right-handed volunteers were studied with echo-planner MR imaging (1.5 T) while performing alternating finger apposition tasks with both hands. During the hand tasks, the areas of activated pixels were compared between subregions (precentral, central, and postcentral) of the contralateral and ipsilateral sensorimotor cortex. RESULTS: The activated area of the contralateral sensorimotor cortex was significantly larger than that of the ipsilateral cortex during tasks with either hand, whereas the ipsilateral activated area was significantly larger during the left-handed task than during the right-handed task. Ipsilateral activation was greatest in the precentral region, less in the central region, and least prominent in the postcentral region. CONCLUSIONS: Our results confirmed those of previous investigators that ipsilateral activation is more pronounced during left-sided movements than during right-sided movements. The variation in activation of the precentral, central, and postcentral subregions suggests different roles of the ipsilateral and contralateral hemispheres during motor tasks.

Adult↗
PubMed1998

[Effects of folic acid supplementation on hyperhomocysteinemia in CAPD patients: effects on unsaturated fatty acids].

Hyperhomocysteinemia has been recognized as one of the risk factors for atherosclerosis and premature vascular disease. Patients on dialysis and end-stage renal disease also manifest high plasma concentrations of homocysteine. We performed this study to evaluate the effects of folic acid supplementation on hyperhomocysteinemia in CAPD patients. Twenty-three CAPD patients (8 males, 15 females, 49.1 +/- 14.2-years-old) dialyzed for 22.7 +/- 19.2 months participated in the study. Daily 5-mg doses of folic acid supplementation for 4 weeks significantly reduced plasma concentrations of total homocysteine (p < 0.01) and serine (p < 0.001). This observation suggests that the reduction of plasma concentrations of total homocysteine results from activation of homocysteine remethylation to methionine. On the other hand, folic acid supplementation also revealed significant correlations between changes in serum concentrations of both dihomo-gamma-linolenic acid and arachidonic acid and changes in plasma concentrations of total homocysteine (r = -0.517, p < 0.05, r = -0.451, p < 0.05, respectively). In addition, serum concentrations of both dihomo-gamma-linolenic acid and arachidonic acid in 11 CAPD patients with hyperhomocysteinemia (> or = 35 micromol/litter) were significantly lower than those of 12 CAPD patients with normohomocysteinemia (< 35 micromol/litter) (p < 0.05, p < 0.05, respectively). Serum concentrations of both dihomo-gamma-linolenic acid and arachidonic acid in CAPD patients with hyperhomocysteinemia increased significantly (p < 0.01, p < 0.05, respectively) and reached similar levels of CAPD patients with normohomocysteinemia, while plasma concentrations of total homocysteine decreased after folic acid supplementation. These findings suggest that correction of hyperhomocysteinemia in patients on dialysis produces an increase in unsaturated fatty acids.

Administration, Oral↗
PubMed1998

Lymphoblastic lymphoma of natural killer cell origin, presenting as pancreatic tumour.

AIMS: We describe the first case of lymphoblastic lymphoma (LBL) of natural killer (NK) cell origin initially presenting as a pancreatic tumour, and review this type of lymphoma. METHODS AND RESULTS: A 38-year-old woman with abdominal pain was found to have a pancreatic mass. Twenty days later, she developed diffuse lung infiltrates and leucoerythroblastosis of the peripheral blood, and her bone marrow was diffusely infiltrated with blasts. The blasts were positive for CD56, CD16 and P-glycoprotein, but lacked cytoplasmic azurophilic granules, T. B and myeloid cell markers on the cell surface, rearrangement of the genes for T-cell receptor and immunoglobulin, and the Epstein-Barr virus (EBV) genome. The diagnosis was LBL of NK cell origin. She received aggressive therapy, but died of the lymphoma. In contrast to ordinary NK-cell lymphoma, this case and reported cases of LBL of NK-cell origin showed the following common characteristics. The tumour cells often lack cell surface CD2, cytoplasmic CD3, cytoplasmic azurophilic granules, and EBV genome. The prognosis was extremely poor. CONCLUSIONS: LBL of NK-cell origin should be included in the differential diagnosis of pancreatic tumours. To fully characterize this type of lymphoma, further cases must be evaluated.

Adult↗
PubMed1998

[Propofol-air-oxygen anesthesia reduces the incidence of sore throat after laryngeal mask anesthesia].

We investigated the effects of the presence or absence of N2O in propofol anesthesia using a laryngeal mask on the incidence of postoperative sore throat. In the N2O-combined anesthesia group (n = 25), score 0 (no sore throat) was observed in 11 patients; score 1 (slight pain and discomfort that improved on the next day of operation) in 9; and score 2 (persistent pain on the next day) in 5. In the non-N2O-combined anesthesia group (n = 25), score 0 was observed in 21 patients, score 1 in 3; and score 2 in 1, showing a significantly lower incidence of sore throat and milder sore throat than in the N2O-combined anesthesia group. These results suggest that propofol anesthesia using a laryngeal mask not combined with N2O reduces the incidence of postoperative sore throat.

Adult↗
PubMed1998

A clinical analysis of the recovery from sensory disturbance after sagittal splitting ramus osteotomy using a Semmes-Weinstein pressure aesthesiometer.

A number of studies of evaluation methods for sensory disturbance after sagittal splitting ramus osteotomy (SSRO) are known. To compare postoperative sensory disturbances among patients in different hospitals, a highly reproducible and standardized sensory test is required. In the present study, we measured the tactile threshold in the region innervated by the mental nerves in 45 patients (90 sides) after SSRO using a Semmes-Weinstein pressure aesthesiometer. The percentage of recovery to the normal level defined by Bell was 72.2% at one week, 82.2% at 4 weeks, and 90.0% at 8 weeks after SSRO. The recovery process was evaluated by classifying the postoperative sensory disturbance into 5 grade levels according to Bell's interpretation scale. The results showed that the SW sensory test is useful for evaluation of the recovery process from sensory disturbance after SSRO. Some improvements of this test were also discussed.

Adult↗
PubMed1997

The Co2+ Adsorption Properties of Al2O3, Fe2O3, Fe3O4, TiO2, and MnO2 Evaluated by Modeling with the Frumkin Isotherm

Adsorption of Co(II) ions on metal oxides is related to radioactive 60Co(II) (de)contamination of nuclear power plants, Co(II) ion retention in soils as a plant nutrient, concentration of Co(II) in deep-sea manganese nodules, and other applications. Here, the amount of adsorbed Co(II) on metal oxides was measured as a function of the pH and concentration of Co(II) ions, and the adsorption properties of metal oxides were evaluated with a model that considers simultaneous (1:1) and (1:2) exchange reactions between Co2+ aqua ions and surface hydroxyl protons obeying the Frumkin isotherm. The possibility of participation of mono- and polynuclear Co(II) hydroxo complexes in the adsorption was examined, and it was suggested that these species play no role under the conditions here. From the model parameters, it was found that the Co2+ adsorption ability of metal oxides increases in the order Al2O3 < Fe2O3 < TiO2 < Fe3O4 < MnO2, showing a good correlation to the electronegativity Xi of the lattice metal ions of the oxides. The Co2+ adsorption was divided into two processes: (1) deprotonation of surface hydroxyl sites and (2) bonding of Co2+ to the deprotonated sites with a negative charge. With increasing Xi, process 1 increases possibly due to the decrease in the donor electron density responsible for covalent bonds with protons, while process 2 changes only slightly. It was suggested that process 2 is due to ionic bond formation ("electrostatic contact adsorption"), which is independent of the donor electron density, and the correlation of the overall process to Xi found here was ascribed to process 1 above. Copyright 1997 Academic Press. Copyright 1997Academic Press

Journal Article↗
PubMed1997

Adsorption Affinity of Divalent Heavy Metal Ions for Metal Oxides Evaluated by Modeling with the Frumkin Isotherm

Adsorption of divalent heavy metal ions, M(II), on metal oxides is important to determine the behavior of ions in waters and soils. The amount of adsorbed Pb(II), Cu(II), Zn(II), Co(II), Ni(II), and Mn(II) ions on the two oxides MnO2 and Fe2O3 was measured as a function of the pH and concentration of the ions under the conditions where no mono- and polynuclear hydroxo complexes play a role in the adsorption. The adsorption affinity of these ions for the oxides was evaluated with a model that considers simultaneous (1:1) and (1:2) exchange reactions between M2+ aqua ions and surface hydroxyl protons (surface complexation) obeying the Frumkin isotherm. From the model parameters, it was found that the affinity order for (1:1) complex formation is Cu2+ > Mn2+ > Zn2+ > Co2+ > Ni2+ for MnO2 and Pb2+ > Cu2+ > Zn2+ > Co2+ for Fe2O3. A large affinity of Mn2+ for MnO2 was ascribed to the oxidation of this ion by MnO2. A good correlation between the stability constants of (1:1) surface complexes and those of (1:1) hydroxo complexes in solution was obtained. The adsorption affinities of ions here are the affinities for deprotonated hydroxyl sites with negative charge, since for all the ions the oxides are common and the deprotonation properties of hydroxyl sites are the same. The good correlation suggests that the two reactions are similar: From electrostatic theory including crystal field corrections, the both reactions could be regarded as due to ionic bond formation between the positive charge of metal ions and the negative charge of deprotonated sites on oxides or hydroxide ions in solution, as we have suggested previously. Copyright 1997 Academic Press. Copyright 1997Academic Press

Journal Article↗
PubMed1997

Construction and expression of chimeric rat liver hydroxysteroid sulfotransferase isozymes.

The St-20 and ST-40 cDNAs encode rat liver hydroxysteroid sulfotransferases (HS-ST) that are 90% identical in amino acid sequence but exhibit different substrate preferences for dehydroepiandrosterone (DHEA), androsterone (AD), and cortisol (CS). ST-40 is active for all three substrates, whereas ST-20 is mainly active for cortisol. To determine the domain responsible for the substrate preferences of the HS-STs, 20 chimeric HS-STs were constructed by reciprocal exchanges of DNA fragments derived from the cDNAs and were expressed in Escherichia coli. Some chimeric enzymes were enzymatically active for all three substrates, and some displayed reduced or lost CS-ST activity, with retention of DHEA- and AD-ST activities. Others lost all HS-ST activity. Analysis revealed that a central region (region III spanning amino acids 102-164 with five amino acid differences between ST-20 and ST-40) is essential for HS-ST activity, whereas regions II (amino acids 65-101) and IV (amino acids 165-219) are unimportant with regard to substrate preference. It was also shown that the parental combination of regions I (amino acids 1-64) and V (amino acids 220-284) is essential for CS-ST activity. Photoaffinity labeling with [35S]3'-phosphoadenosine 5'-phosphosulfate (PAPS) revealed that some inactive chimeras lost affinity for PAPS. These results suggested that an ordered structure formed by regions I, III, and V is required for HS-ST activity, especially for substrate preference and PAPS binding.

Androsterone↗
PubMed1997

High sulfotransferase activity for phenolic aromatic odorants present in the mouse olfactory organ.

Mouse nasal cytosols show high sulfotransferase (ST) activities toward phenolic aromatic odorants, but have little activities for most alcoholic aromatic odorants. Most ST activities toward the phenolic odorants preferred slightly acidic pH (6.4) and were sensitive to 2,6-dichloro-4-nitrophenol, a specific inhibitor for phenol ST (P-ST) but were not inhibited by triethylamine and tetra-n-butylammonium chloride, which are specific inhibitors for hydroxysteroid ST (HS-ST). These results suggested that P-ST activities are responsible for sulfation of the phenolic odorants. The spectra of the ST activities for these odorants were similar in mouse nasal and liver cytosols, however, nasal cytosols showed much higher ST activity toward cinnamyl alcohol than liver cytosols. This activity preferred higher pH (7.4) compared to the phenolic odorant-ST activities and was inhibited by both types of inhibitors, specific for P-ST and HS-ST. These results appear to indicate the participation of multiple ST isoforms for the sulfation of odorants in mouse nasal cytosols. The existence of P-ST(s) active for the phenolic odorants in olfactory cytosols suggests a role in odorant perception, in particular, in the signal termination process.

Alcohols↗
PubMed1997

Transgenic rescue from embryonic lethality and renal carcinogenesis in the Eker rat model by introduction of a wild-type Tsc2 gene.

We recently reported that a germ-line insertion in the rat homologue of the human tuberous sclerosis gene (TSC2) gives rise to dominantly inherited cancer in the Eker rat model. In this study, we constructed transgenic Eker rats with introduction of a wild-type Tsc2 gene to ascertain whether suppression of the Eker phenotype is possible. Rescue from embryonic lethality of mutant homozygotes (Eker/Eker) and suppression of N-ethyl-N-nitrosourea-induced renal carcinogenesis in heterozygotes (Eker/+) were both observed, defining the germ-line Tsc2 mutation in the Eker rat as embryonal lethal and tumor predisposing mutation. To the best of our knowledge, this is the first report of rescue from a naturally occurring dominantly inherited cancer. This transgenic rescue system will be useful to analyze Tsc2 gene function, its relation to tumorigenesis in vivo, and genetic-environmental interactions in carcinogenesis.

Animals↗
PubMed1997

Second primary carcinoma in the residual cervical esophagus after thoracic esophagectomy: report of five cases.

BACKGROUND AND OBJECTIVES: Development of second primary carcinomas after thoracic esophagectomy has become of much concern, because recently the prognosis of thoracic esophageal carcinoma after esophagectomy with extended lymph node dissection has been improving. We report our experience of diagnosing and treatment second primary carcinomas arising in the remaining esophagus after thoracic esophagectomy. METHODS: Among 253 patients who underwent esophagectomy for thoracic esophageal carcinoma more than 2 years previously, second primary esophageal carcinomas developed in five (2.0%), and these five patients were examined. RESULTS: All second primary carcinomas were found by endoscopy, and were diagnosed as superficial carcinoma (Tis or T1) of the residual cervical esophagus. One patient underwent laser irradiation, another endoscopic mucosal resection, two had surgical mucosectomy, and one segmental resection of the esophagus. After the second treatment, three patients were disease free for 37-38 months, one died of recurrent disease of the first carcinoma 36 months later, and one died of distant metastases of the second carcinoma 8 months later. There have been no local recurrences after treatments for the second primaries. CONCLUSIONS: A variety of low-trauma treatments were employed for the second carcinomas because they were found at an early stage. Endoscopic follow-up is proposed to detect second lesions at an early stage.

Carcinoma, Squamous Cell↗
PubMed1997

Natural killer cells in the late decades of human life.

We examined the lymphocyte subsets and indices of natural killer (NK) cell activity (lytic unit (LU), index of absolute NK cell activity in vivo (ALU), and NK cell activity on a per-cell basis (PCNK)) in 82 people (age, 30-99 years) who were immunologically normal. Although the number of NK cells was maintained throughout the examined age range, the ALU and PCNK values correlated negatively with age. We then examined whether any of the various immunologic parameters, including the function and cell counts of NK cells, T cells, and neutrophils, related to past infectious episodes and death in the follow-up period in 44 elderly subjects (age, 63-98 years). Only low ALU and PCNK values correlated with a past history of severe infection, while low LU, ALU, and PCNK values were the only parameters which correlated with death due to infection during the follow-up period. We propose that human NK cells do not escape the aging process and that a low NK cell function relates to the development of severe infections, which may be fatal, in elderly subjects.

Adult↗
PubMed1997

The spread of methicillin-resistant Staphylococcus aureus in a rural community: will it become a common microorganism colonizing among the general population?

At Fujiwara Memorial Hospital (FMH), a community hospital with 140 beds located near a large agricultural area in Akita prefecture, the annual number of patients colonized with methicillin-resistant Staphylococcus aureus (MRSA) has been increasing in recent years. To elucidate the current status of MRSA spread, the frequency of its isolation among a total of 10598 bacteriological specimens obtained from patients treated at FMH between July 1989 and December 1994 was evaluated. The frequency increased from 3.8% in 1990 to 9.6% in 1994, and of all the patients colonized with MRSA, outpatients accounted for 4.5% in 1990 and 34.9% in 1994. These outpatients included patients from long-term care facilities, those cared for at home with chronic diseases, and those who had been hospitalized in tertiary general hospitals. This remarkable increase in the percentage of outpatients colonized with MRSA may suggest the spread of MRSA in our community.

Ambulatory Care↗