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Biomedical subjects

M Sato

Publications and source records attributed to M Sato.

At least 469 records · Page 26Linked to original sources
PubMed2000

Reduction in bone formation and elevated bone resorption in ovariectomized rats with special reference to acute inflammation.

Changes in bone modeling and remodeling in the tibia of growing rats within 30 days of ovariectomy (ovx) were evaluated by histomorphometric, mechanical; and biochemical means. Three days after ovx, suppressed bone formation was seen. This was shown by reduced osteoid volume, osteoblast surface, and bone formation rate in the secondary spongiosa, and a reduced longitudinal growth rate in the growth plate. In addition, the alkaline phosphatase and tartrate-resistant acid phosphatase activity in bone marrow supernatants was suppressed in conjunction with elevated serum sialic acid levels, indicating inflammation. Although estrogen deprivation itself may provoke the inflammatory process, the serum sialic acid level in the ovx group returned to the baseline level within 5 days after surgery, while that of estradiol in the ovx group remained consistently lower. This suggests that surgical stress, not estrogen deprivation, is the primary cause of the inflammatory response shortly after ovx. A significant difference (p < 0.01) between the ovx and sham rats was seen in the osteoclast surface, which peaked on day 7 in the ovx rats. On day 14 postovariectomy, the bone formation rate peaked and remained constant until day 30. In the ovx rats, there was a sustained reduction in the serum albumin level until day 30. Estrogen deprivation may be the primary cause of these changes, because both surgical ovx and medical oophorectomy with gonadotropin-releasing hormone agonist (G(nRHa) reduce the serum albumin level. In numerous studies dealing with changes after ovx in rats, we have observed: 1) a transient reduction in bone formation in relation to inflammatory changes evoked by ovx surgery, and 2) a sustained reduction in the serum albumin level for at least 30 days after ovx that is possibly due to estrogen deprivation.

Alkaline Phosphatase↗
PubMed2000

An iso-integral mapping technique using magnetocardiogram, and its possible use for diagnosis of ischemic heart disease.

We have developed an iso-integral mapping technique that uses magneto-cardiogram (MCG) data to obtain a map as projected total current image on the torso from the heart. We have also investigated the applicability of iso-integral mapping to the diagnosis of ischemic heart disease. We simulated and measured the characteristics of two types of iso-integral maps: one using tangential (Bxy) components, and one using the normal component (Bz). Each vector component was measured by two types of superconducting quantum interference device (SQUID) system to determine the tangential and normal components. The tangential component of the magnetic field appeared to be equivalent to the current image in the myocardium projected on the observing plane, and we were able to obtain a projected total current image by integration of the tangential components during the depolarization and repolarization processes. And we found that the iso-integral maps of normal hearts showed similar pattern in both processes; however, those of ischemic hearts showed different patterns.

Action Potentials↗
PubMed2000

Potentiation of antitumor effect of NKT cell ligand, alpha-galactosylceramide by combination with IL-12 on lung metastasis of malignant melanoma cells.

The combined therapeutic effect of natural killer T (NKT) cell ligand alpha-galactosylceramide (alpha-GalCer) and IL-12 against highly metastatic B16-BL6-HM melanoma cells was investigated. In comparison with a single administration of alpha-GalCer or IL-12, the combined treatment of tumor-bearing mice with alpha-GalCer plus IL-12 caused a super-induction of serum IFN-gamma levels, though alpha-GalCer-induced IL-4 production was rather inhibited. In parallel with the augmented IFN-gamma production, the natural killing activity against YAC-1 cells and syngeneic B16-BL6-HM melanoma was greatly augmented by the combined therapy. The major effector cells responsible for natural killing activity induced by alpha-GalCer plus IL-12 were enriched in both NK1.1+ TCRalphabeta+ NKT cells and NK1.1+ TCRalphabeta- NK cells. The preventing effect of alpha-GalCer or IL-12 alone against lung metastasis of B16-BL6-HM was also enhanced by the combination therapy. The antitumor activity of alpha-GalCer was totally abolished in NKT-deficient mice. However, IL-12-induced antitumor activity was not eliminated in NKT-deficient mice though it was inhibited by anti-asialo GM1 Ab treatment. These findings suggested that alpha-GalCer synergistically act with IL-12 to activate both NKT cells and NK cells, which may play a critical role in the strong prevention of distant tumor metastasis at early stages of tumor-bearing. These data will provide a novel tool for the prevention of tumor metastasis using NKT-specific ligands alpha-GalCer and IL-12.

Animals↗
PubMed2000

Human scavenger receptor B1 is involved in recognition of apoptotic thymocytes by thymic nurse cells.

Recognition and uptake of apoptotic cells by neighboring phagocytes is essential for the clearance of dying cells without accompanying inflammation or tissue damage. In the thymus, many apoptotic cells are generated in the process of negative selection, and both thymic macrophages (professional phagocytes) and nursing thymic epithelial cells (nursing TEC; nonprofessional phagocytes) recognize and ingest them. However the receptors responsible for this recognition and uptake have not been identified. In the present study, we have established a human nursing TEC line and examined the expression of several genes of the scavenger receptor family considered to be potential receptors for apoptotic cells. Human scavenger receptor-B1 (hSR-B1)/CLA-1, previously shown to recognize apoptotic cells, was strongly expressed in nursing TEC, whereas there was little or no expression of the other scavenger receptors tested: scavenger receptor class A, CD36, or CD68. Suppression of hSR-B1/CLA-1 expression using antisense oligonucleotides decreased the binding of apoptotic thymocytes to nursing TEC by more than 40%. These results indicate that hSR-B1/CLA-1 may play a major role in the clearance of apoptotic cells in the thymus, mediating the recognition and ingestion of apoptotic thymocytes by nursing TEC.

Animals↗
PubMed2000

Over-expression of TSC-22 (TGF-beta stimulated clone-22) markedly enhances 5-fluorouracil-induced apoptosis in a human salivary gland cancer cell line.

We have recently isolated TSC-22 (transforming growth factor-beta-stimulated clone-22) cDNA as an anticancer, drug-inducible (with vesnarinone) gene in a human salivary gland cancer cell line, TYS. We have also reported that TSC-22 negatively regulates the growth of TYS cells and that down-regulation of TSC-22 in TYS cells plays a major role in salivary gland tumorigenesis (Nakashiro et al, 1998). In this study, we transfected TYS cells with an expression vector encoding the TSC-22-GFP (green fluorescent protein) fusion protein, and we established TSC-22-GFP-expressing TYS cell clones. Next, we examined (a) the subcellular localization of the fusion protein, (b) the sensitivity of the transfectants to several anticancer drugs (5-fluorouracil, cis-diaminedichloroplatinum, peplomycin), and (c) induction of apoptotic cell death in the transfectants by 5-fluorouracil treatment. The TSC-22-GFP fusion protein was clearly localized to the cytoplasm, but not to the nucleus. Over-expression of the TSC-22-GFP fusion protein did not affect cell growth, but significantly increased the sensitivity of the cells to the anticancer drugs (p < 0.01; one-way ANOVA). Furthermore, over-expression of the TSC-22-GFP fusion protein markedly enhanced 5-fluorouracil-induced apoptosis. These findings suggest that over-expression of TSC-22-GFP protein in TYS cells enhances the chemosensitivity of the cells via induction of apoptosis.

Antineoplastic Agents↗
PubMed2000

Assembly pathway of desmoglein 3 to desmosomes and its perturbation by pemphigus vulgaris-IgG in cultured keratinocytes, as revealed by time-lapsed labeling immunoelectron microscopy.

To determine the assembly pathway of desmoglein 3 (Dsg3) into desmosomes and the subsequent effects of pemphigus vulgaris immunoglobulin G (PV-IgG) on such, we employed a time-lapsed labeling for FITC/Rhodamine (Rod) double-stained immunofluorescence and 5-nm/10-nm gold double-stained immunoelectron microscopy by using PV-IgG, which was confirmed to react specifically Dsg3. Cells from a human squamous cell carcinoma cell line (DJM-1) were first treated briefly with PV-IgG (3 min), then incubated in either anti-human IgG-FITC or 5-nm gold antibody-containing medium (5 min), followed by a 60-minute chase in normal medium without antibodies. The same cells were reincubated with PV-IgG medium for 3 minutes, followed by either anti-human IgG-Rod or 10-nm gold antibodies for 5 minutes. Using this method, FITC and 5-nm gold particles show the fate of Dsg3-PV-IgG complexes during the following 60-minute chase. IgG-Rod or 10-nm gold particles, which are bound during the last 5 minutes of the chase, show Dsg3 molecules newly expressed on the cell surface during the 60-minute-chase period. Initially, Dsg3 formed two types of small clusters on the nondesmosomal plasma membrane, ie, either half-desmosome-like clusters with keratin intermediate filament (KIF) attachment or simple clusters without KIF attachment. The PV-IgG binding to Dsg3 caused the internalization of the simple clusters into endosomes, but not the half-desmosome-like clusters. After the 60-minute-chase period, both types of cell surface Dsg3 clusters were labeled with only 10-nm gold, suggesting that new Dsg3 molecules were being delivered to the cell surface. Desmosomes were labeled with both 5-nm gold and 10-nm gold, whereas the half-desmosome-like clusters were labeled with only 10-nm gold, suggesting that the desmosomes themselves were not split. These results suggest that Dsg3 first forms simple clusters, followed by KIF-attachment, and then becomes integrated into desmosomes, and that PV-IgG-induced internalization of the nondesmosomal simple clusters of Dsg3 may represent the primary effects of PV-IgG on keratinocytes.

Autoantigens↗
PubMed2000

Biological control of an insect pest by gut-colonizing Enterobacter cloacae transformed with ice nucleation gene.

The ice nucleation (IN) gene inaA of epiphytic Erwinia (Pantoea) ananas IN10 was transformed into Enterobacter cloacae WBMH-3-CMr originated from the faeces of silkworms. The transformant designated as Ent. cloacae WBMH-3-CMr(pICE6S13) exhibited IN activity, unlike the parent strain. The transgenic strain was ingested by mulberry pyralid larvae, fed on detached mulberry leaves, and the supercooling capacity and cold hardiness of these larvae were examined. The mean supercooling point (SCP) of the larvae ingesting the transgenic strain was - 3.3 degrees C, 8 degrees C higher than that of larvae treated with distilled water (control) and 1.5 C higher than an ice nucleation active (INA) strain of Erw. ananas. The SCPs of the larvae were stably maintained over the 9 d after ingestion. The maintenance of these high SCPs was due to transgenic Ent. cloacae having a more stable and efficient gut colonization than Erw. ananas, which is identified by the distribution of a narrower range of SCPs (-2 to -5 degrees C) in larvae treated with the transgenic stain. Furthermore, most of the larvae ingesting the transgenic strain froze and died when they were exposed to cold conditions of -5 degrees C for 18 h, 3 or 7 d after ingestion. In contrast, most of the larvae ingesting no bacterium did not die under similar conditions. On the other hand, the growth ability of Ent. cloacae WBMH-3-CMr on mulberry leaves tended to be lower than that of epiphytic Erw. ananas, as assayed by pot tests. These findings would expand the possibility of biological control using INA bacteria since Ent. cloacae would harbour a broader host (insect) range for gut colonization and a smaller affinity to plants to benefit from prevention of plant frost injury.

Animals↗
PubMed2000

Development of clover yellow vein virus as an efficient, stable gene-expression system for legume species.

A highly infectious cDNA clone of clover yellow vein virus (pClYVV) was tested as a viral vector, especially for legume species. The genes for green fluorescent protein (GFP) and soybean glutamine synthetase (GS) were inserted between the genes for P1 and HC-Pro on pClYVV to create three recombinant plasmids: pClYVV-GFP, pClYVV-GFP-GS, and pClYVV-GFP:GS. In the former two constructs all the junctions between the inserted proteins contained the sequences of protease cleavage recognition sites, whereas the third construct expressed a fusion of GFP and GS. Western blot analyses showed that GFP and GS appeared to have been precisely excised from the viral polyprotein with the viral proteases (P1 and NIa). Under UV irradiation, green fluorescence was detected in infected broad bean, kidney bean, and soybean plants. The stability of the constructs in the symptomatic tissues was confirmed by RT-PCR and Western blot analyses. The plants expressing GS together with GFP became tolerant to the herbicide glufosinate, and flowered early. As the GS gene, one of the nodulin genes for nitrogen fixation, is expressed in legume species, this system will be useful for examining the function of genes important to legume plants.

Blotting, Western↗
PubMed2000

Transforming growth factor beta induction of insulin gene expression is mediated by pancreatic and duodenal homeobox gene-1 in rat insulinoma cells.

Although transforming growth factor-beta (TGF-beta) stimulates pancreatic islet cells to synthesize and secret insulin, the mechanism underlying this effect is not known. To investigate this question, we examined the insulin promoter activity focusing on a transcription factor, pancreatic and duodenal homeobox gene-1 (PDX-1) that binds to the A3 element of the rat insulin promoter. Studies performed using the rat insulinoma cell line, INS-1 showed that TGF-beta stimulation of endogenous insulin mRNA expression correlated with increased activity of a reporter construct containing the insulin promoter. A potential mechanism for this increase arose from, electrophoretic mobility shift assay showing that the nuclear extract from TGF-beta treated cells contained higher levels of A3 binding activity. Western blot analysis confirmed that PDX-1 was increased in the nuclear extract from INS-1 cells treated with TGF-beta. As expected, a mutant insulin promoter that lacked the PDX-1 binding site was not stimulated by TGF-beta. In summary, the results of these studies show that TGF-beta stimulates the transcription of insulin gene and this action is mediated by the transcription factor, PDX-1.

Animals↗
PubMed2000

Review article: acute inorganic mercury vapor inhalation poisoning.

Mercury contamination is a serious environmental problem worldwide. Two primary sources of contamination are dumping of large quantities of inorganic mercury and exposure in the mining industry. Although the actual fatal level of mercury vapor is not known, exposure to more than 1-2 mg/m3 of elemental mercury vapor (Hg0) for a few hours causes acute chemical bronchiolitis and pneumonitis. Two hours after exposure, lung injury appears as hyaline membrane formation, and finally, extensive pulmonary fibrosis occurs. Clinical findings correlate with the duration of exposure, the concentration of mercury, and the survival time after exposure. There is no correlation between pathological findings and the concentration of mercury in the tissues. Necrosis of proximal convoluted tubules may be attributed to the disruption of the enzyme systems of Hg2+-sulfhydryl compounds. Metallothionein protein (MT), induced by the accumulation of Hg2+ in the kidneys, may play an important role in detoxication after it forms a non-toxic Hg2+-MT compound. Despite the deposition of mercury in the brain, compared with organic mercury, inorganic mercury did not seem to damage the neurons. Drugs such as chelating agents and corticosteroids appear to effectively decrease the inflammation and delay pulmonary fibrosis.

Environmental Exposure↗
PubMed2000

Analysis of the immunoglobulin heavy chain gene of secondary diffuse large B-cell lymphoma that subsequently developed in four cases with B-cell chronic lymphocytic leukemia or lymphoplasmacytoid lymphoma (Richter syndrome).

The immunoglobulin heavy chain gene (IgH gene) was analysed in four cases of B-cell Richter syndrome, in order to determine whether a secondary diffuse large B-cell lymphoma (DLBCL) could arise from the same clone as the initial B-cell chronic lymphocytic leukemia (B-CLL) and lymphoplasmacytoid lymphoma (LPL) or be a de novo event, and whether secondary DLBCL shows an intraclonal microheterogeneity. Both the initial B-CLL and secondary DLBCL in two cases expressed CD5 antigen. Both samples of the initial B-CLL or LPL and the secondary DLBCL in three cases were examined for comparison. The polymerase chain reaction-amplified IgH gene of secondary DLBCL in two cases (CD5+ case and CD5- case) were different from those of the initial B-CLL, revealing a new malignant clone. The other case (CD5-) showed that secondary DLBCL had a sequence identical to the initial LPL, indicating the same clonal origin. The variable region of the IgH gene of secondary DLBCL (CD5+ two cases and CD5- two cases) exhibited a 0.5-9.0% somatic mutation range and no intraclonal microheterogeneity.

Aged↗
PubMed2000

Significance of simultaneous determination of serum human chorionic gonadotropin (hCG) and hCG-beta in testicular tumor patients.

BACKGROUND: Simultaneous determinations of human chorionic gonadotropin hormone (hCG) and hCG-beta frequently produce discrepancies, that is when hCG or hCG-beta is normal, the other is elevated. Accordingly, we examined the significance of simultaneous determination of serum hCG and hCG-beta in testicular tumors. METHODS: Simultaneous determination of hCG and hCG-beta was performed in 54 patients with testicular seminoma and 74 with non-seminomatous testicular tumors. RESULTS: For detection of seminoma patients, hCG-beta was more effective than hCG because hCG-beta was positive in 83% (45/54) of the patients and hCG was positive in 50% (27/54). In non-seminomatous testicular tumor cases, hCG-beta was positive in 74% (55/74) and hCG was positive in 82% (61/74). The cases of hCG<1.0 mIU/mL and HCG-beta>0.1 ng/mL were significantly more frequently seen in patients with seminoma than in those with non-seminomatous testicular tumor (P < 0.001). Fourteen patients had recurrent tumor. At recurrence, only hCG was elevated in nine cases, only hCG-beta was elevated in two cases and both in one case. For diagnosis of falsely positive hCG, testosterone administration was effective because after testosterone administration, serum hCG levels became undetectable (< 1.0 mIU/mL) within one week in three examined cases. CONCLUSION: Human chorionic gonadotropin-beta was a better marker of seminoma than hCG. For earlier detection of recurrence, both markers should be examined. For diagnosis of falsely positive hCG, testosterone administration was effective.

Adult↗
PubMed2000

A2-Pancortins (Pancortin-3 and -4) are the dominant pancortins during neocortical development.

We have identified a novel mouse gene named pancortin that is expressed dominantly in the mature cerebral cortex. This gene produces four different species of proteins, Pancortin-1-4, sharing a common region in the middle of their structure with two variations at the N-terminal (A1 or A2 part) and C-terminal (C1 or C2 part) sides, respectively. In the present study, we showed that expression of mRNAs for A2-Pancortins (Pancortin species that contain the A2 part, i.e., Pancortin-3 and -4) is more dominant than that of mRNAs for A1-Pancortins (Pancortin species that contain the A1 part, i.e., Pancortin-1 and -2) in the prenatal mouse cerebral neocortex. Using western blot analysis, we found that substantial amounts of both A2-Pancortins were present in the prenatal cerebral neocortex and P19 cells after inducing neuronal differentiation. A2-Pancortins were still present in the cerebral neocortex of the adult, although their mRNAs were hardly detected. In contrast, the amount of A1-Pancortins did not increase after the third postnatal week in spite of their intense gene expression. Furthermore, we showed that recombinant Pancortin-3, one of the A2-Pancortins, was a secreted protein, in contrast to Pancortin-1 (one of the A1-Pancortins). These results suggest that A2-Pancortins are extracellular proteins essential for neuronal differentiation and that their molecular behavior is distinct from that of A1-Pancortins.

Alkaline Phosphatase↗
PubMed2000

Sensorless controlling method for a continuous flow left ventricular assist device.

We originated a novel control strategy for a continuous flow left ventricular assist device (LVAD). We examined our method by acute animal experiments to change the left ventricular (LV) contractility or LV end-diastolic pressure (LVEDP). To estimate the pump pulsatility without any specific sensor, we calculated the index of current amplitude (ICA) from motor current waveform. The ICA had a peak point (t-i point) that corresponded closely with the turning point from partial to total assistance, and a trough (s-i point) that corresponded with the beginning point of ventricular collapse. The pump flow at the t-i point (Qt-i) had no component of flow regurgitation. In the evaluation of the effects of preload LVEDP, afterload (mAoP), and contractility (max LV dp/dt), we found that preload was the only parameter that significantly influenced Qt-i. We concluded that our method could well control continuous flow LVAD by preventing reversed flow and ventricular collapse.

Animals↗
PubMed2000

Enlarged entry space for the transpetrosal approach.

This report describes the removal of the roof of the external auditory meatus in approaching the tentorial edge, the cerebropontine angle, hippocampal brainstem lesions, and upper clival lesions. This procedure not only provides more space in approaching the tentorial edge or upper brainstem, it also provides a wider entry space for approaching posterior fossa lesions. This approach is also for lesions located lower than the tentorium or in the upper clivus. There is still some confusion about the method for removing the roof of the external auditory canal. We describe the clinical experience and comprehensive surgical procedures used on cadavers. Our extended temporal craniotomy technique using the removal of the roof of the external auditory meatus is a simple, safe, and useful method for obtaining a wider entry space to approach deep perimesencephalic lesions and the posterior fossa.

Journal Article↗
PubMed2000

Isolated heterotopic pancreas causing intussusception.

Pediatric intussusception is usually idiopathic in origin, and a pathological lesion at the leadpoint is identified in only a small proportion of cases. Meckel's diverticulum is the most common location when such a lesion is found. Heterotopic pancreas has been seen most frequently in the stomach or duodenum; however, ileal lesions are rare. In the ileum, heterotopic pancreas is usually associated with Meckel's diverticulum and may cause intestinal obstruction by intussusception. However, isolated heterotopic pancreas in the ileum is distinctly rare and usually discovered incidentally during surgery for other conditions. In a review of English language literature, there were only a few pediatric cases of isolated ileal heterotopic pancreas causing intussusception. We report three additional pediatric cases and discuss the clinical significance of this unexpected rare entity.

Choristoma↗