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Biomedical subjects

H Kawamura

Publications and source records attributed to H Kawamura.

At least 37 records · Page 2Linked to original sources
PubMed2004

Age-related bias in function of natural killer T cells and granulocytes after stress: reciprocal association of steroid hormones and sympathetic nerves.

Stress-associated immune responses were compared between young (8 weeks of age) and old (56 weeks) mice. Since stress suppresses the conventional immune system (i.e. T and B cells) but inversely activates the primordial immune system (i.e. extrathymic T cells, NKT cells, and granulocytes), these parameters were analysed after restraint stress for 24 h. The thymus became atrophic as a function of age, and an age-related increase in the number of lymphocytes was seen in the liver. Although the number of lymphocytes in both the thymus and liver decreased as the result of stress, the magnitude was much more prominent in the thymus. To determine stress-resistant lymphocyte subsets, two-colour immunofluorescence tests were conducted in the liver and spleen. NKT cells were found to be such cells in the liver of young mice. On the other hand, an infiltration of granulocytes due to stress was more prominent in the liver of old mice than in young mice. Liver injury as a result of stress was prominent in young mice. This age-related bias in the function of NKT cells and granulocytes seemed to be associated with a difference in the responses of catecholamines (high in old mice) and corticosterone (high in young mice) after stress. Indeed, an injection of adrenaline mainly induced the infiltration of granulocytes while that of cortisol activated NKT cells. The present results suggest the existence of age-related bias in the function of NKT cells and granulocytes after stress and that such bias might be produced by different responses of sympathetic nerves and steroid hormones between young and old mice.

Aging↗
PubMed2004

[Aortic valve papillary fibroelastoma; report of a case].

Papillary fibroelastoma is a rare cardiac tumor. We report a case of surgical treatment for aortic valve papillary fibroelastoma. The patient was a 64-year-old female. She admitted our hospital for the evaluation of cardiogenic cerebral infarction. The echocardiogram revealed a mobile rounded mass (10 x 6 mm) of the aortic valve and aortic regurgitation. On the basis of these echo findings, we performed operation. Under cardiopulmonary bypass, aortotomy was made and aortic valve was observed. A tumor was on the non-coronary-cusp of the aortic valve, which was successfully removed followed by aortic valve replacement with 21 A Carpentier-Edwards bio-prosthetic valve. The tumor was histologically diagnosed papillary fibroelastoma. Following uncomplicated postoperative course, the patient was discharged on twenty-first postoperative day.

Aortic Valve↗
PubMed2003

Long-term implantation of zinc-releasing calcium phosphate ceramics in rabbit femora.

Zinc is an essential trace element that has stimulatory effects on bone formation. Recently, we developed zinc-releasing calcium phosphate ceramics in order to add the pharmacologic effect of zinc to calcium phosphate ceramics. In our previous study, we showed that the optimum zinc content for promoting bone formation was 0.316 wt %. Therefore a zinc composite ceramic of zinc-containing beta-tricalcium phosphate and hydroxyapatite, with a zinc content of 0.316 wt %, was chosen for long-term implantation. Cylindrical rods of the zinc composite ceramic were implanted in rabbit femora for 2 to 60 weeks. Using computer-aided image analysis, a histomorphometric study was carried out to investigate bone formation and resorption around the implants. The control was a composite ceramic of beta-tricalcium phosphate and hydroxyapatite without zinc. The addition of zinc to the implant demonstrated both favorable and unfavorable effects on bone remodeling. The favorable effect was enhanced bone apposition to the implant surface, demonstrated by a significant increase in intramedullary bone apposition rate at 6 weeks and in cortical bone apposition rate at 24 and 60 weeks (p < 0.05). The unfavorable effect was increased bone resorption, demonstrated by a significant increase in medullary cavity area at 60 weeks (p < 0.05). In order to utilize the favorable effect and avoid the unfavorable effect of zinc, either a reduction in zinc content in the zinc composite ceramic or the selection of implantation sites that do not have excessive exposure to bone marrow are required.

Animals↗
PubMed2003

Intake and excretion of 99Tc in a common sea alga, hijiki (Hizikia fusiforme), as ingested in the daily diet--a measurement in an adult male.

Ingestion and excretion of environmental 99Tc was measured in an adult male who ingested 'hijiki' food in his diet that contained a sub-bequerel activity per kg, and which was prepared from a marine alga, Hizikia fusiforme, or hijiki in Japanese, traditionally eaten in the Japanese diet. Harvested hijiki was boiled, dried and cooked. This was eaten at each meal five times over 2 d. All faeces and 24-h urine samples were collected during the 3 d before and subsequent 11 d starting from the day when the intake began. The ingestion intake was measured by analysing the dried hijiki material. 99Tc was determined by using liquid-liquid extraction and low-background beta ray spectrometry. The excreta were also analysed for minerals by atomic absorption spectrometry. The apparent absorption rate in the gastrointestinal tract for 99Tc under these conditions was calculated to be approximately 0.5. The present result from a single subject indicates the need for further studies.

Administration, Oral↗
PubMed2003

Thorium concentration in Pakistani diet.

To evaluate radiation doses due to ingestion of thorium activity by members of the public, baseline analytical data on thorium concentration in a typical Pakistani diet was generated. Food samples were collected from major districts/ cities of the country using the market basket method, and typical daily diets were prepared. Thorium concentration was determined by instrumental neutron activation analysis. It was found to vary from 1.6 ng g(-1) to 12 ng g(-1). The median value was 4.6 ng g(-1). This leads to median daily thorium intake of 2.7 microg d(-1). The geometric mean was 2.6 microg d(-1), which was 13% less than the ICRP value. Based on these measurements the average intake of 232Th activity was 10 mBq d(-1), and the average annual and committed effective doses for adults were estimated to be 8.8 x 10(-7) Sv y(-1) and 4.4 x 10(-5) Sv, respectively.

Diet↗
PubMed2002

Infantile gliosarcoma: a case and a review of the literature.

INTRODUCTION: Gliosarcoma in infant is a very rare entity. CASE REPORT: The authors present a case of gliosarcoma in a 23-month-old boy. The patient was admitted to our hospital with persistent headache and frequent vomiting. MR imaging demonstrated a large frontal well-circumscribed lesion with a heterogeneous gadolinium enhancement. Although macroscopically the tumor was totally extirpated, the boy died of rapid tumor regrowth 2 months after surgery. The surgical specimens obtained from the tumor showed an admixture of two distinctive neoplastic tissues. One was a malignant mesenchymal feature. Its fibrosarcomatous nature was characterized by spindle-shaped cells with fine fibers that were deeply stained in silver preparations for reticulin. The other was gliomatous tissue forming islands surrounded by the sarcomatous tissues. Its glioblastomatous nature was obvious, as it was characterized by endothelial proliferation and perinecrotic pseudopalisading. Both tissues were histologically malignant, as evidenced by mitotic figure, high cellularity, atypical features, and variability. DISCUSSION: The literature concerning gliosarcomatous tumors is reviewed, and pathological and clinical features of the tumor are briefly discussed.

Brain Neoplasms↗
PubMed2002

Intercomparison of INAA and ICP-MS results for thorium determination in Pakistani diet.

A pilot study on ingestion and organ content of trace elements of importance in radiological protection was to be carried out in Pakistan. Baseline analytical data on daily dietary intake of thorium was to be measured using Instrumental Neutron Activation Analysis (INAA) technique. To determine the accuracy and reliability of our technique, some samples were measured in Pakistan using INAA and in Japan using Inductively Coupled Plasma-Mass Spectrometry. For intercomparison of results overall mean Z-scores were calculated. The results showed validity of our technique. Mean value of 232Th concentration in Pakistani diet samples using INAA technique is 0.0062 +/- 0.0028 microg/g and with ICP-MS technique is 0.0069 +/- 0.0032 microg/g.

Diet↗
PubMed2002

Intramucosal naevus with pseudoepitheliomatous hyperplasia in the gingiva: a case report.

This article describes the unusual case of an intraoral pigmented naevus with pseudoepitheliomatous hyperplasia of the gingiva. A 62-year-old man presented with an almost coal-black pigmented and partly white, spotted, dome-shaped swelling on the lingual gingiva of the mandible. Histologically, the lesion consisted of clusters of round-shaped naevus cells containing melanin granules, reactive with both S-100 immunohistochemical stain and Masson-Fontana silver stain, and pseudoinvasive squamous nests, reactive with cytokeratin. The pathogenesis of the present lesion and problems encountered in its differential diagnosis are discussed.

Basal Cell Carcinoma↗
PubMed2002

Feeding behaviour of infants with cleft lip and palate.

AIM: To determine whether the feeding behaviour of infants with cleft lip and palate is improved with a type-P teat, which is widely used in Japan by such infants, compared with a standard teat. The difference in intra-oral movements between the type-P teat, modified for the evaluation of feeding behaviour, and an unmodified type-P teat was also compared using ultrasonography. METHODS: In part 1 of the study, 15 infants aged 2 to 3 mo and 7 infants aged 2 wk were evaluated for sucking pressure, expression pressure, frequency and duration of sucking. All the infants had a complete unilateral cleft lip and palate without any other abnormalities. In part 2, an ultrasonographic analysis of intra-oral movement was done for 5 infants enrolled in part 1 of the study. RESULTS: Sucking pressure did not occur in all infants. It was found that feeding efficiency improved with the type-P teat compared with the standard teat. The expression pressure with the type-P teat was significantly higher than that with the standard teat, and the feeding frequency with the type-P teat was lower than that with the standard teat. CONCLUSION: A type-P teat is suitable for infants with cleft lip and palate who have sucking difficulties. However, a type-P nipple with a squeezable bottle does not fully solve the feeding problems of infants with cleft lip and palate. New artificial teats that allow a higher expression pressure are desirable, and the measurement of the expression pressure may be helpful in the evaluation of artificial nipples.

Cleft Lip↗
PubMed2001

New delta (distorted-bcc) titanium to 220 GPa.

Structural phase transitions of a 3d transition element, titanium, have been investigated at pressures up to 220 GPa at room temperature using a monochromatic synchrotron x-ray diffraction technique. At 140 GPa, the hexagonal (omega) phase was transformed into an orthorhombic (delta) phase with a distorted bcc structure via an intermediate (gamma) phase, which has recently been proposed by Vohra and Spencer [Phys. Rev. Lett. 86, 3068 (2001)]. Both the delta and the gamma phases had a unique zigzag-chain-like structure, which resulted from an orthorhombic distortion. The delta-gamma transition could be explained as a rearrangement of the packing between the zigzag chains.

Journal Article↗
PubMed2001

Ordering of the three-dimensional Heisenberg spin glass in magnetic fields.

Spin and chirality orderings of the three-dimensional Heisenberg spin glass are studied under magnetic fields in light of the recently developed spin-chirality decoupling-recoupling scenario. It is found by Monte Carlo simulations that the chiral-glass transition and the chiral-glass ordered state, which are essentially of the same character as their zero-field counterparts, occur under magnetic fields. The implication to the experimental phase diagram is discussed.

Journal Article↗
PubMed2001

Aging effect in ceramic superconductors.

A three-dimensional lattice of the Josephson junctions with a finite self-conductance is employed to model ceramic superconductors. By using Monte Carlo simulations it is shown that the aging disappears in the strong screening limit. In the weak screening regime, aging is present even at low temperatures. For intermediate values of the self-inductance, aging occurs in an intermediate temperature interval but is suppressed entirely at high and low temperatures. Our results are in good agreement with experiments.

Journal Article↗
PubMed2001

Association of intermediate T cell receptor cells, mainly their NK1.1(-) subset, with protection from malaria.

Mice were infected with Plasmodium (P.) yoelii blood-stage parasites. Both the liver and spleen were the sites of inflammation during malarial infection at the beginning of day 7. The major expanding cells were found to be NK1.1(-) intermediate alphabetaTCR (alphabetaTCR(int)) in the liver and spleen, although the population of NK1.1(+) alphabetaTCR(int) cells remained constant or slightly increased. These TCR(int) cells are of extrathymic origin or are generated by an alternative intrathymic pathway and are distinguished from conventional T cells of thymic origin. During malarial infection, the population of conventional T cells did not increase at all. TCR(int) cells purified from the liver of mice which had recovered from P. yoelii infection protected mice from malaria when they were transferred into 6.5-Gy-irradiated mice. Interestingly, the immunity against malaria seemed to disappear as a function of time after recovery, namely, mice which had recovered from malaria 1 year previously again became susceptible to malarial infection. The present results suggest that TCR(int) cells are intimately associated with protection against malarial infection and, therefore, that mice which had recovered from malaria 1 year previously lost such immunity.

Animals↗
PubMed2001

Abundance of unconventional CD8(+) natural killer T cells in the large intestine.

Natural killer T (NKT) cells are mainly present in the liver and thymus, and the majority of these T cells express either a CD4(+) or a double-negative (DN) CD4(-)8(-) phenotype. In the present study, we examined whether such NKT cells were present in the intestine. NKT cells were rare in all sites of the small intestine, including an intraepithelial site. However, a considerable number of NKT cells were found at an intraepithelial site in the large intestine. This result was confirmed by both immunofluorescence and immunohistochemistry. In contrast to conventional NKT cells, NKT cells in the large intestine were CD8(+) or DN CD4(-)8(-). In the case of conventional NKT cells, their existence is known to depend on non-classical MHC class I-like antigens (i. e. CD1d) but not on classical MHC class I antigens. However, the NKT cells in the large intestine were independent of the presence of both CD1d and classical MHC class I antigens. These results were obtained using knockout mice lacking the corresponding genes and molecules. NKT cells in the large intestine were mainly alpha betaTCR(+) (> 75 %) but did not use an invariant chain of Valpha14Jalpha281, which is preferentially used by conventional NKT cells. These NKT cells did not bias the TCR-Vbeta usage toward Vbeta8. These findings suggest that the large intestine is a site in which unconventional NKT cells carrying the CD8(+) phenotype (or DN CD4(-)8(-)) are abundant and that these cells are independent of MHC and MHC-like antigens.

Animals↗
PubMed2001

Nitric oxide/cGMP-induced inhibition of calcium and chloride currents in retinal pericytes.

In the CNS, contractile pericytes positioned on endothelium-lined lumens appear to play a role in regulating capillary blood flow. This function may be particularly important in the retina where pericytes are more numerous than in other tissues. Despite the importance of pericytes, knowledge of the effects of vasoactive molecules, such as nitric oxide (NO), on the physiology of these cells is limited. Since it is likely that ion channels play a role in the response of pericytes to signaling molecules from other cells, we used the perforated-patch configuration of the patch-clamp technique to record the whole-cell currents of pericytes located on microvessels freshly isolated from the rat retina. We found that voltage-gated calcium currents and calcium-activated chloride currents were inhibited during exposure to the NO donor, sodium nitroprusside (SNP). 8-Bromo-cyclic guanosine monophosphate (cGMP) mimicked these effects. In contrast, neither SNP nor the cGMP analog significantly affected the potassium or nonspecific cation conductances, which establish the resting membrane potential of retinal pericytes. Consistent with endogenous NO suppressing pericyte channel activity, exposure of isolated microvessels to an inhibitor of NO synthase increased the calcium and chloride currents. Since our experiments indicate that chloride channel activity is dependent, in part, upon the function of voltage-gated calcium channels, we postulate that a NO/cGMP-mediated inhibition of calcium channels reduces calcium influx and, thereby, lessens the opening of the calcium-activated chloride channels. This may be one mechanism by which NO decreases the contractile tone of pericytes.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed2001

A clinicopathologic study of mucinous adenocarcinoma of the stomach.

BACKGROUND: Mucinous adenocarcinoma of the stomach is a rare histologic type of gastric adenocarcinoma and its features are still controversial. We attempted to clarify the clinicopathologic characteristics of this histologic type. METHODS: We reviewed the records of 112 patients with mucinous adenocarcinoma of the stomach (MUC) and 4160 patients with nonmucinous gastric adenocarcinoma (NMUC) for factors including age; sex; tumor location, size, and depth; lymph node metastasis; lymphatic or venous permeation; peritoneal dissemination; liver metastasis; and survival rate. We also investigated the relationship between cancer depth and lymph node metastasis. Statistical analysis included chi 2 and Student's t-tests. Survival rates were calculated by the Kaplan-Meier method and analyzed by the log rank test. RESULTS: MUC was found mostly in younger patients, in the lower part of the stomach and was of larger size, invading to or beyond the muscularis propria, positive for lymph node involvement, and associated with peritoneal dissemination. The overall 5-year survival rate in patients with MUC was lower than that in NMUC patients, because the MUC patients more frequently had advanced stage disease; however, the survival rates in the two groups did not differ significantly. As for the relationship between cancer depth and lymph node involvement, the frequency of lymph node metastasis increased when invasion reached the submucosa in patients with MUC compared with those with NMUC while the frequency of lymph node metastasis increased in the muscularis propria in patients with NMUC compared with those with NMUC. CONCLUSION: MUC was characteristically found in younger patients, at lower sites, at an advanced stage, and with peritoneal dissemination; MUC had a poor prognosis. Lymph node metastasis should be suspected when MUC invades to the submucosa or deeper.

Adenocarcinoma, Mucinous↗