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Biomedical subjects

Y Tamura

Publications and source records attributed to Y Tamura.

At least 235 records · Page 13Linked to original sources
PubMed1997

Inhibition of aldose reductase and sorbitol accumulation by astilbin and taxifolin dihydroflavonols in Engelhardtia chrysolepis.

Dihydroflavonol taxifolin and its glycoside, astilbin, from Engelhardtia chrysolepis inhibited rat lens and recombinant human aldose reductase. Taxifolin also inhibited sorbitol accumulation in human red blood cells. Furthermore, this dihydroflavonol aglycone maintained the clarity of rat lens incubated with a high concentration of glucose. These dihydroflavonols may be effective for preventing osmotic stress in hyperglycemia.

Aldehyde Reductase↗
PubMed1997

Detection of Clostridium septicum hemolysin gene by polymerase chain reaction.

A polymerase chain reaction (PCR) was developed for the detection of the hemolysin (alpha toxin) gene of Clostridium septicum. The PCR primers were designed from the sequence of the hemolysin gene and synthesized. A DNA fragment of 270 bp was amplified from 10 strains of C. septicum, but was not from strains of C. chauvoei, C. perfringens, C. novyi, or C. haemolyticum. When the PCR product was digested with Sau3AI, two DNA fragments of the expected 148 bp and 122 bp were recognized. The lowest detectable threshold of PCR for the hemolysin gene was 3.8 x 10(3) cells/ml. The PCR technique may be useful for rapid detection or identification of C. septicum associated with malignant edema.

Animals↗
PubMed1997

Effects of intraluminal or extraluminal endothelin on perfused rabbit basilar arteries.

The authors investigated selective intra- and extraluminal effects of endothelin (ET) on perfused basilar and extracranial arteries and also studied the interaction between ET and extraluminal oxyhemoglobin (oxyHb). The basilar, mesenteric, and femoral arteries were isolated from 23 Japanese White rabbits. After isolation of the intra- and extraluminal sides of the preparation, 3 x 10(-10) to 3 x 10(-8) mol/L of ET was administered intra- or extraluminally. After extraluminal pretreatment with 10(-5) mol/L oxyHb, 10(-5) mol/L N(G)-monomethyl-L-arginine (L-NMMA), or 10(-6) mol/L indomethacin, 10(-10) to 10(-8) mol/L of ET was administered intra- or extraluminally. Arterial contraction was evaluated by measuring the increase in the perfusion pressure gradient with a differential pressure gauge. Both intra- and extraluminal ET (10(-9) to 3 x 10(-8) mol/L) showed potent and dose-dependent vasoconstricting effects on basilar arteries (p < 0.01). The effect of ET on the basilar arteries was significantly greater than on the femoral or mesenteric arteries (both p < 0.01). The effect of intraluminal ET was enhanced by extraluminal oxyHb (p < 0.05) and L-NMMA (p < 0.01), but not by extraluminal indomethacin. Extraluminal oxyHb did not potentiate the contraction induced by extraluminal ET. These results indicate that the sensitivity of the basilar artery to intraluminal ET is greater than that of the femoral or mesenteric artery. Endothelin may act as a potent vasoconstrictor intra- as well as extraluminally under conditions such as subarachnoid hemorrhage in which oxyHb is present in the extraluminal space and endothelium-derived relaxing factors are inhibited.

Animals↗
PubMed1997

[Relationship of pollen counts of Japanese cedar to weather factors in Isehara City, Kanagawa].

We investigated the relationship of pollen counts of Japanese cedar to 9 different weather factors including means of the highest, and lowest temperatures, variation in temperatures mean of the lowest humidity on a day, daily mean, maximum wind velocity and daily wind direction in 1991, 1992, 1993 and 1995 in Isehara City, Kanagawa Prefecture. The results were as follows: 1. In each year, the highest temperature and the mean humidity were statistically related to the maximum pollen counts of Japanese cedar in the air. 2. Mean pollen counts per day on the days that the wind from the southwest were much higher than on the days with wind from the south. 3. These wind directions coincided with the dense plantation areas of Japanese cedar trees around Isehara City. We concluded that in terms of accurate daily forecasting of pollen counts in the air in a certain area or city, it should be taken into consideration that the highest temperature, and mean humidity together with the wind direction from the area of dense population of Japanese cedar trees surrounding the area are closely related to the increased pollen count per day.

Humidity↗
PubMed1997

Protective effects of methylcobalamin, a vitamin B12 analog, against glutamate-induced neurotoxicity in retinal cell culture.

PURPOSE: To examine the effects of methylcobalamin on glutamate-induced neurotoxicity in the cultured retinal neurons. METHODS: Primary cultures obtained from the fetal rat retina (gestation days 16 to 19) were used for the experiment. The neurotoxicity was assessed quantitatively using the trypan blue exclusion method. RESULTS: Glutamate neurotoxicity was prevented by chronic exposure to methylcobalamin and S-adenosylmethionine (SAM), which is formed in the metabolic pathway of methylcobalamin. Chronic exposure to methylcobalamin and SAM also inhibited the neurotoxicity induced by sodium nitroprusside that release nitric oxide. By contrast, acute exposure to methylcobalamin did not protect retinal neurons against glutamate neurotoxicity. CONCLUSIONS: Chronic administration of methylcobalamin protects cultured retinal neurons against N-methyl-D-aspartate-receptor-mediated glutamate neurotoxicity, probably by altering the membrane properties through SAM-mediated methylation.

Animals↗
PubMed1997

Tricuspid inflow and regurgitant flow dynamics after mitral valve replacement: differences relating to surgical repair of the tricuspid valve.

BACKGROUND AND AIMS OF THE STUDY: Changes in tricuspid inflow and regurgitant flow dynamics were evaluated in patients with functional tricuspid regurgitation (TR) who underwent mitral valve replacement (MVR) with and without tricuspid annuloplasty (TAP). METHODS: In a group of 30 patients, all with atrial fibrillation, 15 underwent TAP performed according to the modified De Vega technique; the remaining 15 did not undergo TAP. Patients were studied before and serially after surgery, using pulsed and color Doppler echocardiography. The mean follow up was 4.7 years in the TAP group and 5.1 years in the non-TAP group. RESULTS: In the TAP group, immediately after surgery, the area of the TR jet decreased markedly, and the deceleration time of the tricuspid inflow velocity wave was significantly prolonged compared with that before surgery. By contrast, in the non-TAP group, both the area of the TR jet and deceleration time of tricuspid inflow velocity were virtually unchanged. The area of the TR jet remained small for a long period in the TAP group, but in non-TAP patients was increased in four cases over seven years, with two patients developing right-sided heart failure. Recent data showed the area of the TR jet to be significantly smaller, with maximum tricuspid inflow velocity significantly increased, and deceleration time of the tricuspid inflow velocity wave significantly prolonged in the TAP group compared with the non-TAP group. CONCLUSIONS: In patients with functional tricuspid regurgitation undergoing MVR, concomitant TAP may cause mild tricuspid stenosis, but produces sustained preventive effects against TR. Careful follow up is needed in patients who have not undergone TAP, as TR is not markedly decreased and may even be exacerbated. Aggressive TAP is recommended in patients showing dilatation of the tricuspid annulus, even if TR is mild.

Adult↗
PubMed1997

[Two cases of advanced gastric cancer effectively treated with chemotherapy of 5-fluorouracil, cisplatin and cytarabine].

We reported two cases of advanced gastric cancer effectively treated with chemotherapy of 5-fluorouracil (5-FU), cisplatin (CDDP) and cytarabine (Ara-C), 5-FU (300-350 mg/body) was given by continuous intravenous infusion. Ara-C (20-40 mg/body) by continuous infusion and CDDP (15-20 mg/body) were added intravenously for 3-6 days. For case 1, epirubicin (30 mg/body) was also given on the first day of each therapy course. Case 1 was a 62-year-old female who had gastric cancer with liver metastasis, ovarian metastasis and peritonitis carcinomatosa. After 3 courses of the chemotherapy, reduction of ovarian metastasis greater than 75% was observed. The value of CA125 decreased from 6,800 U/ml to 527 U/ml and ascites disappeared. Case 2 was a 54-year-old male who had type 3 advanced gastric cancer with multiple liver metastases. He received 6 courses of the therapy. Both primary and metastatic tumors showed over 50% reduction in tumor size. These suggested that this combination therapy was effective for inoperable advanced gastric cancers.

Adenocarcinoma↗
PubMed1997

Cause and repair of flap necrosis over cochlear implant.

OBJECTIVE: The aim of this report was to study the cause and treatment of flap-related complications over cochlear implant. SETTING: The study was performed in an academic tertiary referral center. PATIENT: A 53-year-old Japanese male patient had had two retro-auricular skin incisions for tympanomastoidectomy in the postauricular region before implantation of a cochlear implant. He also had worn a helmet daily during work in his factory. INTERVENTIONS: Corrective surgery was performed for reformation of the local blood supply to the overlying skin flap and reinforcement of the tissue overlying the implant by use of a superiorly based temporal muscle and fascia flap that were sutured with an inferiorly based muscle and fascia flap. RESULTS: We successfully transposed the flap covering the implant without explantation of the implant. CONCLUSIONS: The delayed development of flap necrosis was thought to be due to pressure necrosis produced by the band in the patient's helmet lying on the skin over the implant and to poor local blood supply in the postauricular area stemming from the two previous skin incisions for mastoid surgery performed for cholesteatoma. In those patients who wear helmets, it is important to position the cochlear implant sufficiently behind the ear and to avoid the use of a helmet.

Cochlear Implants↗
PubMed1997

[An adult case of purulent meningitis secondary to retropharyngeal and deep neck abscess after treatment of odontogenic infection].

Retropharyngeal and deep neck abscess, which may follow odontogenic infection, is uncommon in adults, but can be fatal. Furthermore, bacterial meningitis secondary to this disorder is extremely rare. A 67-year-old man was brought to our hospital because he had developed neck pain, trismus, and disturbance of consciousness over several days. A few days prior to the appearance of neck pain, he had the periodontitis treated. Based on CSF, cervical X-ray and CT findings, he was diagnosed as having bacterial meningitis secondary to deep neck abscess. Culture of the CSF yielded gram-positive cocci, later identified as Gemella species, that is a rare organism for bacterial meningitis. Although the administration of antibiotics and drainage of the abscess resulted in gradual improvement of the infectious process, neurologically he remained with apallic syndrome. We would like to stress the importance of odontogenic and pharyngolaryngogenic sources as potential foci of purulent meningitis.

Abscess↗
PubMed1996

Pituitary adenylate cyclase-activating polypeptide protects rat-cultured cortical neurons from glutamate-induced cytotoxicity.

We have investigated the effects of pituitary adenylate cyclase-activating polypeptide with 38 residues (PACAP38) on glutamate-induced neuronal cell death in rat-cultured cortical neurons. The rat-cultured neurons were obtained from E17 day-old embryos and cultured in a chemically defined medium without serum for 10 days, after which more than 95% of the cells were stained by a specific antibody against MAP-2, a specific marker for neurons. The number of viable neurons was identified by the mitochondrial conversion of 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) to formazan, which was detected by the associated change in optical density at 570 nm. Glutamate-induced neuronal cell death was suppressed by PACAP38 at concentrations as low as 10(-13) M, and at 10(-11) M maximally suppressed half of the amount of glutamate-induced cell death seen in a control situation (no PACAP38). The dose-response curve was bell-shaped. Dibutyryl cAMP (dbcAMP) also increased the number of neurons that were protected from damage with a bell-shaped dose-response curve suggesting that PACAP exerts its neuroprotective effect through the activation of a cAMP signal transduction system. However, cAMP accumulation in the media of neurons was stimulated by PACAP38 at concentrations as low as 10(-11) M, a much higher concentration than the minimal effective dose of PACAP38 required for protection against glutamate-induced neuronal cell death. Among the three neuropeptides of PACAP38, arginine vasopressin (AVP) and C-type natriuretic peptide (CNP), only PACAP38 exhibited a neurotrophic effect in the glutamate-induced neuronal cell death at the indicated concentrations. These data indicate that PACAP38 is one of the more important neuroprotective factors. The kind of intracellular signal transduction system involved in the neuroprotective effect of PACAP38 still remains to be established.

Animals↗
PubMed1996

Molecular epidemiology of breast cancers in northern and southern Japan: the frequency, clustering, and patterns of p53 gene mutations differ among these two low-risk populations.

Comparison of acquired mutations in the p53 tumor suppressor gene can illuminate factors contributing to carcinogenesis among cancer cohorts. Japan has an ethnically homogeneous population with a low incidence of breast cancer. Previously we reported an unusual frequency, allelic status, and clustering of mutations in breast cancers from the northern part of the main Japanese island. To extend these findings, exons 2-11 and adjacent intronic sequences were analysed in tumors of women from northern (Hokkaido) and southern (Tokushima) Japan. The frequency of breast cancers with p53 gene mutations in the Hokkaido group is the highest reported (81%) while that in Tokushima (28%) is similar to most other populations. Thirteen of the 19 mutations (68.4%) in the Hokkaido cohort were heterozygous, an unusually high frequency for p53 mutations in any tumor type. There were three missense mutations at codon 175, a known hotspot for alterations in the p53 gene, and three missense mutations at codon 179, a rare site for p53 changes. In addition, the patterns of p53 gene mutation differed between the two Japanese cohorts (P=0.04). The multiple differences in acquired p53 mutations suggest unsuspected biological differences among breast cancers in northern and southern Japan. In addition, the high frequency of p53 mutations in breast cancers from Hokkaido predicted a poorer prognosis for this population which was confirmed on examination of mortality data.

Adult↗
PubMed1996

Involvement of peptide antigens in the cytotoxicity between 70-kDa heat shock cognate protein-like molecule and CD3+, CD4-, CD8-, TCR-alpha beta- killer T cells.

We previously reported that the 70-kDa heat shock cognate protein-like molecule (hsc70) is expressed on the cell surface along with the neoplastic transformation of rat fibroblast and that this molecule is recognized by CD3+, CD4-, CD8-, NKR-P1-, and TCR-alphabeta- T (DNT) killer cells in an MHC class I-unrestricted fashion. We investigated the mechanism of interaction between hsc70 and DNT cells. H-ras oncogene-transformed rat fibrosarcoma W31 cells expressed hsc70 on the cell surface in almost the same density when the cells were growing in a conventional 5% FCS (5% W31) as when the cell growth was inhibited in the cultivation with 1% FCS (1% W31). However, DNT cells lysed only 5% W31, but not 1% W31. Since these observations suggest that certain peptide Ags of the fast growing W31 cells may play a role in the interaction between hsc70 and DNT cells, we pulsed 1% W31 cells with trifluoroacetic acid (TFA)-extracted fast growing W31 tumor Ags of less than 3000 Da in molecular size. We also pulsed 1% W31 with TFA-extracted Ags from moderate growing W14 tumors and whole fetus tissues. Our data indicated that DNT cells were clearly cytotoxic to 1% W31 pulsed only with TFA-extracted Ags from W31 tumors. Anti-rat hsc70 mAb completely blocked this cytotoxicity. In addition, pronase K treatment of Ags clearly inhibited the cytotoxicity by DNT cells. Taken together, these data suggest that the complex of peptide Ag and hsc70 is involved in the cytotoxic mechanism between hsc70 and DNT cells.

Animals↗
PubMed1996

Induction of Graves-like disease in mice by immunization with fibroblasts transfected with the thyrotropin receptor and a class II molecule.

Graves disease is an autoimmune thyroid disease characterized by the presence of antibodies against the thyrotropin receptor (TSHR), which stimulate the thyroid to cause hyperthyroidism and/or goiter. By immunizing mice with fibroblasts transfected with both the human TSHR and a major histocompatibility complex class II molecule, but not by either alone, we have induced immune hyperthyroidism that has the major humoral and histological features of Graves disease: stimulating TSHR antibodies, thyrotropin binding inhibiting immunoglobulins, which are different from the stimulating TSHR antibodies, increased thyroid hormone levels, thyroid enlargement, thyrocyte hypercellularity, and thyrocyte intrusion into the follicular lumen. The results suggest that the aberrant expression of major histocompatibility complex class II molecules on cells that express a native form of the TSHR can result in the induction of functional anti-TSHR antibodies that stimulate the thyroid. They additionally suggest that the acquisition of antigen-presenting ability on a target cell containing the TSHR can activate T and B cells normally present in an animal and induce a disease with the major features of autoimmune Graves.

Animals↗