Search PubMed⌕ Search

Biomedical subjects

M Tamura

Publications and source records attributed to M Tamura.

At least 217 records · Page 12Linked to original sources
PubMed1999

Analysis of optical signals evoked by peripheral nerve stimulation in rat somatosensory cortex: dynamic changes in hemoglobin concentration and oxygenation.

The origins of reflected light changes associated with neuronal activity (optical signals) were investigated in rat somatosensory cortex with optical imaging, microspectrophotometry, and laser-Doppler flowmetry, and dynamic changes in local hemoglobin concentration and oxygenation were focused on. Functional activation was carried out by 2-second, 5-Hz electrical stimulation of the hind limb under chloralose anesthesia. These measurements were performed at the contralateral parietal cortex through a thinned skull. Regional cortical blood flow (rCBF) started to rise 1.5 seconds after the stimulus onset, peaked at 3.5 seconds (26.7% +/- 9.7% increase over baseline), and returned to near baseline by 10 seconds. Optical signal responses at 577, 586, and 805 nm showed a monophasic increase in absorbance coincident with the increase in rCBF; however, the signal responses at 605 and 760 nm were biphasic (an early increase and late decrease in absorbance) and microanatomically heterogeneous. The spectral changes of absorbance indicated that the concentrations of both total hemoglobin and oxyhemoglobin increased together with rCBF; deoxyhemoglobin, increased slightly but distinctly (P = 0.016 at 1.0 seconds, P = 0.00038 at 1.5 seconds) just before rCBF increases, then decreased. The authors conclude that activity-related optical signals are greatly associated with a moment-to-moment adjustment of rCBF and metabolism to neuronal activity.

Animals↗
PubMed1999

Transforming growth factor-beta isoforms and receptors in endometriotic cysts of the human ovary.

PROBLEM: The present study examined the presence and cellular distribution of transforming growth factor-beta1, 2, and 3 isoforms and their type I and II receptors in endometriotic cysts of the ovary, relative to their presence in normal endometrial tissue. METHOD OF STUDY: Thirteen control samples of normal endometrium in the proliferative phase and 11 ovarian endometriotic cysts were examined by immunohistochemistry for transforming growth factor-beta1, 2, and 3 isoforms and their type I and II receptors. RESULTS: Immunoreactivity for all ligands and receptors was detected in both normal endometrium and endometriotic cysts. Isoform-specific differences in immunostaining were not detected. Expression of all ligands and receptors was significantly increased in epithelial cells of endometriotic cysts compared with those of normal endometrium. On the other hand, stromal cells in normal endometrium and endometriotic cysts were only faintly immunostained. Inflammatory cells infiltrating among endometriotic stromal cells contained the highest immunostaining intensity for all ligands and receptors. We identified nearly all inflammatory cells as macrophages using a specific antibody. CONCLUSIONS: These findings suggest that macrophages in endometriotic tissue are a major source of transforming growth factor-beta, which may be an important regulator of cell proliferation in endometriotic cysts through paracrine and autocrine actions.

Activin Receptors, Type I↗
PubMed1999

Effects of guar gum and cellulose on cecal enzyme activity and cecal short-chain fatty acids in young and aged mice.

The effects of cellulose or guar gum on cecal enzyme activity and cecal short-chain fatty acids (SCFAs) in young and aged mice were studied. Male Crj:CD-1 (ICR) mice were fed an MF diet for 4 (young mice) or 23 months (aged mice). The MF diet was then replaced with a semisynthetic diet supplemented with 5% guar gum or 5% cellulose. The mice were fed the guar gum or cellulose diet for 3 weeks. There was no significant difference in cecal content between the two diet groups. There were no significant differences in total short-chain fatty acid production between the young mice fed the cellulose and those fed the guar gum diet, and between the aged mice fed the cellulose and guar gum diet. There were significant differences in cecal enzyme activity between the young mice fed the cellulose and those fed the guar gum diet. Beta-glucuronidase activity was significantly higher in the young mice fed the guar gum diet than in those fed the cellulose diet. There were also significant differences in cecal enzyme activity between the aged mice fed the cellulose diet and those fed the guar gum diet. Beta-glucuronidase activity was significantly higher in the aged mice fed the guar gum diet than in these fed the cellulose diet. Beta-glucosidase activity was significantly lower in the aged mice fed the guar gum diet than in those fed the cellulose diet. The effect of cellulose on the microflora between the young and aged mice might be different from the effect of guar gum. The degree of adaptation to the diet of microflora in young and aged mice fed the cellulose diet might differ from that in those fed the guar gum diet. The higher enzyme activities of microflora in aged animals compared to young animals, might have some relation with the incidence of colon cancer in aged animals.

Aging↗
PubMed1999

Adrenomedullin inhibits transmural pressure induced mesangial cell proliferation through activation of protein kinase A.

Adrenomedullin (AM), a hypotensive peptide isolated from human pheochromocytoma, inhibits the proliferation of mesangial cells (MC) induced by mitogens such as platelet-derived growth factor. Quite recently, we have demonstrated that transmural pressure applied to cultured MC increased DNA synthesis and cell proliferation through protein kinase C and tyrosine kinase pathways. However, the modulatory effect of AM on pressure-induced cell proliferation is as yet unknown. In the present study, we examined the effect of AM on transmural pressure-induced DNA synthesis in cultured rat MC. Pressure was applied to cells placed in a sealed chamber using compressed helium. Application of pressure resulted in an increase in [(3)H]thymidine incorporation (approximately 2.0-fold). AM clearly inhibited pressure-induced DNA synthesis in a concentration-dependent manner. This inhibition was paralleled by an increase in cellular cAMP levels evoked by AM. Forskolin and dibutyryl cAMP mimicked the inhibitory effect of AM. The protein kinase A inhibitor H-89 significantly attenuated the effect of AM. Human AM(22-52)-NH(2), a putative AM receptor antagonist, reversed the inhibitory effects of AM more potently than did human CGRP(8-37), a calcitonin gene related peptide receptor antagonist. Our results suggest that AM, by acting mainly on AM-sensitive receptors, inhibits pressure-induced DNA synthesis in cultured rat MC through activation of protein kinase A. AM may play a protective role against MC proliferation in certain pathological conditions.

Adrenomedullin↗
PubMed1999

Intracellular sodium modulates the expression of angiotensin II subtype 2 receptor in PC12W cells.

Although the angiotensin II subtype 2 receptor (AT2-R) is expressed abundantly in the adrenal medulla, its physiological significance has not yet been determined. To obtain fundamental knowledge of the regulation of AT2-R expression in the adrenal medulla, we investigated the effects of modulating several ion channels on AT2-R expression in PC12W cells. Experiments were performed after 24 hours of serum depletion under subconfluent conditions. After 48 hours of treatment with various agonists or antagonists, the receptor density and mRNA level of AT2-Rs were quantified by 125I-[Sar1, Ile8]angiotensin II binding and Northern blot analysis. Ouabain (10 to 100 nmol/L) and insulin (10 to 100 nmol/L) dose-dependently increased receptor density and mRNA level. Analysis of the binding characteristics revealed that the ouabain-dependent increase in AT2-R levels was due to an increase in binding capacity without a change in the Kd value. These increases were blocked by lowering the Na+ concentration in the medium. A low concentration of the sodium ionophore monensin (10 nmol/L), the K+-channel blocker quinidine (10 micromol/L), and the ATP-sensitive K+-channel blockers tolbutamide (100 micromol/L) and glybenclamide (10 micromol/L) also significantly increased receptor density, but the ATP-sensitive K+-channel agonist cromakalim (100 micromol/L) decreased receptor density significantly (P<0.01). Nifedipine (10 micromol/L) decreased basal receptor density and completely blocked the increase in receptor density caused by these agents. The increase in receptor density caused by an increase in intracellular Na+ was accompanied by an increase in mRNA level, whereas the ATP-sensitive K+-channel blockers did not change mRNA level. Nifedipine slightly decreased mRNA level. These results suggest that AT2-R expression is sensitively regulated by intracellular cation levels. The change in intracellular Na+ level transcriptionally regulates AT2-R expression, whereas the K+-channel blocker-dependent upregulation appears to be at least in part posttranslational.

Angiotensin II↗
PubMed1999

Elderly Japanese people living in small towns reflect on end-of-life issues.

This article, reporting on selected data from a larger study, discusses some responses to end-of-life questions that elderly Japanese people who were living in small towns gave in a questionnaire survey. Japan is now the country with the largest number of elderly people in the world and confronts numerous social and economic questions concerning how best to cope with its older population. Although it is a highly urbanized society, Japan also has large semirural areas. The focus here is on the questions in the survey that sought responses to ethical dimensions of end-of-life issues. The findings demonstrate the strength of traditional values that still exist throughout small towns in Japan.

Advance Care Planning↗
PubMed1999

Dendritic cells produce interleukin-12 in hyperthyroid mice.

We previously reported that serum interleukin-12 (IL-12) levels were significantly increased in patients with hyperthyroid Graves' disease and in normal subjects after administration of thyroid hormone. In the present study, we investigated which cells produce IL-12 and the interactions between IL-12 and thyroid hormones, using a hyperthyroid mouse model. Thyroid hormones induced IL-12 production, and IL-12 was mainly produced by dendritic cells outside the thyroid glands in a hyperthyroid state.

Animals↗
PubMed1999

Morphological adaptation of the cardiovascular system in fetal rats during late gestation.

The aim of this study was to evaluate morphological changes of the cardiovascular system in fetal rats during late gestation. We used the rapid whole-body freezing technique for rats of day 17 through 21 of gestation. The right and left ventricular volumes increased markedly and significantly during this period by about 11- and 24-fold, respectively. Although the right ventricular volume was 108% larger with statistical significance than the left ventricular volume on day 17, they were almost equal after day 19. The length of the primum septum of the atrium significantly increased by 92% within 4 days, but the opening distance of foramen ovale significantly decreased by 14%. The ratio of the inner diameter (the sum of right and left pulmonary arteries to ductus arteriosus) significantly increased from 0.72+/-0.03 on day 17 to 1.17+/-0.07 on day 21. There was also a significant increase in the ratio of the inner diameters of the ascending to descending aorta. These observations suggest that the reduction of the opening distance of foramen ovale reflect the growth of pulmonary arteries.

Adaptation, Physiological↗
PubMed1999

A clinicopathological study of lung cancer patients with occupational exposure to chrysotile asbestos fibers.

OBJECTIVE: To summarize the features of asbestos-related lung cancer. PATIENTS: Thirty-one lung cancer patients with occupational exposure to chrysotile asbestos fibers. They worked or had worked in one asbestos factory or its subcontracters. RESULT: All patients were male with mean age of 60.6 when diagnosed, and all except one were current or ex-'heavy' smokers. Histological types were fairly evenly divided into adeno-, squamous and small cell carcinoma and 24 (78%) of patients showed 'peripheral type' lung cancers. Regarding clinical stages, 20 patients (65%) were classified as III or IV (advanced stage). Tumor shadow(s) was detected on chest X-ray in 22 patients (71%), and in 5 patients with 'negative' chest X-ray, chest CT was necessary to recognize a primary tumor. Seventeen patients (55%) did not undergo periodical check-ups. CONCLUSION: Occupational asbestos exposure is interpreted as one of the important risks for lung cancer and frequent and accurate observation is necessary.

Adult↗
PubMed1999

The phenomenon of salivary protein adsorption onto Streptococcus mitis ATCC 903 cells.

It is thought that salivary proteins on bacterial cells have some influence on the adhesion of oral bacteria onto the surface of oral tissues and on bacterial aggregation. Initially, this study sought to examine the phenomenon of salivary protein adsorption to the surface of Streptococcus mitis ATCC 903 using 3H-labeled salivary proteins. We investigated the effects of hydrophobic level and lectin-ligand binding on adsorption of salivary proteins, and also the influence of cell surface components on adsorption. The results showed that the adsorption of salivary proteins was clearly reduced by the presence of Tween 20, LiCl, NaSCN, Hexadecane and some sugars. The adsorption was also affected by the pH level, and protease treatment or heat treatment of cells also decreased the volume of adsorbed proteins. Although the adsorption of proteins onto heat-treated cells was dramatically reduced by the presence of LiCl and NaSCN, the presence of sugars had little influence on this adsorption. These findings suggest that the main adsorption of salivary proteins is due to hydrophobic factors, and the heat-sensitive surface components of the cells had some relation to lectin-ligand binding. Therefore, it appears important to study the adsorption of salivary proteins onto cells since the salivary proteins on bacterial cells play an important role in their adherence to the saliva-coated oral tissues and bacterial aggregation.

Adsorption↗
PubMed1999

[Extravasation into a renal sinus cyst due to ureteral calculus: a case report].

A 71-year-old man who had been treated conservatively for advanced prostate cancer with hormonal therapy presented with complaint of left flank pain. Intravenous urography demonstrated obstruction caused by a left upper ureteral calculus and leakage of contrast medium outside the renal pelvis and calyces. Left percutaneous nephrostomy was performed, and subsequent nephrostography showed extravasation into a parapelvic renal sinus cyst previously recognized on follow-up computed tomography (CT). The left ureteral calculus was treated with extracorporeal shock wave lithotripsy (ESWL), after which obstruction and extravasation disappeared. One month later, abdominal CT demonstrated no left renal nor ureteral calculi, as well as a reduction in the left renal sinus cyst. Urinary extravasation sometimes occurs as a complication of acute urinary obstruction. However, extravasation into a cyst is very rare. We have found only one case reported in the literature, so far.

Aged↗
PubMed1999

[Cranial fasciitis of a neonatal case with massive intra- and extracranial extension].

We report a neonatal male case of cranial fasciitis in childhood. He was born with a large skull tumor in his left fronto-parietal region. The day after his birth, he was admitted to our hospital. On inspection, the mass was firm, non mobile, and had two humped peaks. The size of the mass was 7 x 5 x 4 cm, and it was located on the left coronal suture and fontanelle. The overlying skin was normal. Skull X-rays revealed osteolytic defect and linear bone remnant skirted the outer rim of the tumor. CT scan showed a slightly high-density large frontal mass with a low density area in the center of it and marked enhancement. MR images revealed a large mass with massive intra- and extracranial extension. Cerebral angiography showed the remarkable vascularization of the tumor. Preoperatively, the branches of the external carotid artery were partly embolized. On surgery, the profusely bleeding, elastic hard, yellowish-white mass arising from the dura was partially removed with the surrounding bone. A small mass remained subdurally. The boundary of the mass and the dura was not well demarcated. After the operation, no neurological deficits were seen. 16 months after the surgery, MRI revealed the unfolded brain with no evidence of tumor. Histological examination showed characteristic proliferation of spindle-shaped fibroblasts embedded in a collagenous stroma. Inflammatory lymphocytes and acidophils were also noted. Electron micrograph revealed a tumor cell rich in rough endoplasmic reticulum and nuclei with numerous indentations. Immunostaining confirmed that these cells were positive for vimentin but negative for smooth muscle actin, GFAP, S-100 protein, and desmin. No recurrence of this tumor has been detected at four years of follow-up.

Actins↗
PubMed1999

[Analysis of 209 PCB congeners by high separation gas chromatography/low resolution mass spectrometer].

All PCB congeners were analyzed by high separation gas chromatography/low resolution mass spectrometer, using 209 PCB congeners as standards. They were separated into 169 peaks, including 28 peaks containing 2 PCBs and 8 peaks containing 3 PCBs. The rice oil samples of Fukuoka and Taiwan Poisonings were analyzed for PCB congeners. They showed 115 separated peaks of PCB congeners. Total PCB concentrations were 879 and 769 ppm in 2 samples of Fukuoka rice oil and 57 and 83 ppm in 2 samples of Taiwan rice oil.

Environmental Pollutants↗
PubMed1999

[Analysis of all PCB congeners in breast milk and blood of Yusho patients].

Breast milk and blood of Yusho patients were analyzed for polychlorinated biphenyl (PCB) congeners by High separation gas chromatography/Low resolution mass spectrometer. Seventy-one and forty-nine PCB congeners were identified and quantified in the breast milk and blood, respectively. Total PCB concentrations (Whole base) in breast milk of 2 Yusho patients were 69.9 and 15.1 ppb, respectively, being 11.6 and 2.5 times higher than those of 4 control breast milk. Average total PCB concentration of 5.0 ppb in whole blood of 13 Yusho patients was 3.6 times higher than those of control persons. Fourteen PCB congeners, such as 99, 117, 130, 137, 138, 156, 157, 164, 170, 171, 172, 189, 191 and 195, were particularly higher concentration in breast milk and blood of Yusho patients than in those of control persons. Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) and coplanar PCBs were also analyzed in the breast milk of Yusho patients and control persons. Large portions, 83 and 74%, of Dioxin toxic equivalency (TEQ) in the 2 Yusho breast milk were consisted of TEQ of 2,3,4,7,8-pentaCDF only, while total TEQ in the breast milk of control persons was consisted of PCDFs 48%. PCDDs 29% and coplanar PCBs 23%.

Environmental Pollutants↗
PubMed1999

[Surgical results on N2 lung cancer with special reference to correlation between tumor size and extension of lymph node metastases].

Systematic lymph node dissection was performed for every patients undergoing surgical intervention. Since 1981, there were 218 stage IIIA-N2 patients who underwent resection with two operative mortality. The five-year survival rate of whole cases was 22.6%, and that of 152 completely resected cases was 30.0%. Favorable factors on long-term survival of pN2 patients were cN0, T1-2 N2M0, single mediastinal node involvement, and tumor less than 20 mm or less. The five-year survival rates of stage IIIA-N2 patients with tumor diameter of < or = 20 mm, 21-30 mm, 31-50 mm, and > or = 51 mm were 48.1%, 27.7%, 31.2%, and 16.7%, respectively. When micrometastases to lymph node in the p-stage I patients (diagnosed by H-E staining) were examined by immunohistochemical staining, 36 patients (27%) out of 132 verified micrometastases in the lymph nodes.

Humans↗
PubMed1999

[The clinical features of cervical spondylosis with boule musculaire].

To clarify the pathophysiology of boule musculaire associated with cervical spondylosis, we investigated the 13 patients (11 males and 2 females) with cervical radiculopathy caused by cervical spondylosis. None of the patients had any subjective symptoms such as sensory disturbance, weakness in the boule musculaire, and muscle atrophy of the insurround region near the boule musculaire. Among 21 tendon reflexes of the biceps muscle of the arm, 9 were normal, 8 were decreased and 4 were increased. Among the 13 patients there was only 2 clinical cases of cervical myelopathy. MRI obtained from 3 patients demonstrated a compressed cervical cord. Electromyography obtained from 7 patients demonstrated mild neurogenic changes such as polyphasic or prolonged motor unit potential (MUP) in the boule musculaire and in the atrophic regions. However, there was no giant MUP, fasciculation, fibrillation, nor positive sharp waves suggesting denervating lesions below the anterior horn in any patient. It was considered that the boule musculaire observed in cervical spondylosis gradually developed from a relatively mild disturbance of the ventral root. Moreover, the boule musculaire developed more often in the male patients, and predominantly on the right side. Cervical spondylosis accompanying boule musculaire may be a prodromal stage or a mild type of cervical spondylotic amyotrophy.

Aged↗
PubMed1999

A cystatin-related gene, testatin/cresp, shows male-specific expression in germ and somatic cells from the initial stage of murine gonadal sex-differentiation.

Sex-differentiation in mammals initiates at mid-gestation when the differentiation of Sertoli cells is triggered by the expression of the testis-determining gene, Sry. However, little is known about the succeeding germ-soma interaction that directs the sex-differentiation of germ cells. We carried out subtraction and differential screening between male and female gonads at 13.5 dpc (days post coitum). A novel cystatin-related gene was identified and named cresp (cystatin-related expressed in Sertoli and spermatogonia), and has recently been reported independently under the name testatin (Töhönen et al., 1998). The presumed amino acid sequence of testatin/cresp showed considerable homology to the cystatin family, but it lacked a few critical amino acid residues for the cysteine-protease inhibitory activity. A 0.7 kb RNA was detected by northern blotting specifically in the fetal and adult testes from 11.5 dpc and expression increased between 11.5 dpc and 12.5 dpc. Using RT-PCR analysis, the testatin/cresp mRNA was first detectable at 9.5 dpc in both male and female embryos but it was maintained only in the male. In females, the expression became weaker at 11.5 dpc and was undetectable after 12.0 dpc. In situ hybridization and immunohistochemical analyses, as well as single cell RT-PCR analysis, showed that the testatin/cresp mRNA was localized specifically in both the (pro)spermatogonia and Sertoli cells in the testis from 12.5 dpc to adult. Thus, expression of the testatin/cresp gene is upregulated in male gonads but downregulated in females immediately after the initiation of sex-differentiation, suggesting roles in the early developmental cascade of testis such as the germ-soma interaction.

Amino Acid Sequence↗