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Biomedical subjects

M Hosokawa

Publications and source records attributed to M Hosokawa.

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

cDNA cloning and genomic organization of peroxisome proliferator-inducible long-chain acyl-CoA hydrolase from rat liver cytosol.

The cDNA for a peroxisome proliferator-inducible long-chain acyl-CoA hydrolase from rat liver cytosol, referred to as rLACH2, was isolated and its genomic structure was determined. The cDNA encoded a 419-amino-acid polypeptide with a calculated molecular weight of 46,011. Sequence analysis identified an active-site serine motif (Gly-x-Ser-x-Gly) common to carboxylesterases and lipases. When expressed in Escherichia coli, the cDNA directed expression of a protein immunoreactive to an anti-rLACH2 antibody with a molecular mass of 47 kDa, identical to that of purified rLACH2. Northern blot analysis showed marked induction of rLACH2 mRNA in the liver after feeding rats with di(2-ethylhexyl)phthalate, a peroxisome proliferator. The rLACH2 gene spanned about 19 kb and comprised 3 exons, the intron/exon boundaries of which were consistent with the donor/acceptor splice rule. A putative peroxisome proliferator response element (AGGTCATGGTTCA) was identified in the 5'-flanking region, suggesting the involvement of peroxisome proliferator-activated receptors in the regulation of rLACH2 gene expression.

Amino Acid Sequence↗
PubMed1998

Differential catalytic properties in metabolism of endogenous and exogenous substrates among CYP3A enzymes expressed in COS-7 cells.

The catalytic properties of CYP3A7 in the metabolism of endogenous and exogenous substrates were compared with those of CYP3A4 and CYP3A5 using COS-7 expressing enzymes. The highest activities of dehydroepiandrosterone (DHEA) and dehydroepiandrosterone 3-sulfate (DHEA-S) 16alpha-hydroxylase were observed in COS-7 cells expressing CYP3A7. In contrast, the activity of testosterone 6beta-hydroxylase of CYP3A7 expressed in COS-7 cells was much less than that of CYP3A4 expressed in COS-7 cells. The rate of carbamazepine 10, 11-epoxidation was the greatest in COS-7 cells expressing CYP3A4, followed by CYP3A5 and CYP3A7. On the other hand, the formation of reductive metabolite of zonisamide was the highest in COS-7 cells expressing CYP3A4, followed by CYP3A7 and CYP3A5. Furthermore, the addition of triazolam resulted in a decrease in 6beta-hydroxylation catalyzed by CYP3A7, but not by CYP3A4, whereas the pretreatment of microsomes with triacetyloleandomycin (TAO) resulted in a decrease in the reaction catalyzed by CYP3A4, but not by CYP3A7. Together with these results, it was suggested that CYP3A7 exerts differential catalytic properties not only in metabolism of endogenous substrates but also in drug metabolism compared to CYP3A4 and CYP3A5.

Adult↗
PubMed1998

Spontaneous and artificial lesions of magnocellular reticular formation of brainstem deteriorate avoidance learning in senescence-accelerated mouse SAM.

The role of the magnocellular reticular formation (MGRF) of the brainstem on learning and memory was examined in memory-deficient mice with spontaneous spongy degeneration in the brainstem (senescence-accelerated mouse, SAMP8) and control mice (accelerated-senescence resistant mouse, SAMR 1). SAMP8 showed spontaneous age-related impairment of learning and memory, as determined by passive and active avoidance responses. The deficits of learning and memory function in passive avoidance performances began at two months of age and increased with ageing. In the brains of SAMP8 at one month of age and older, spongy degeneration was mainly observed in the brainstem, while no vacuoles were evident in SAMR1 control (normal ageing mouse) brains in the age range tested (up to 12 months). The vacuolization in SAMP8 was marked in the MGRF, especially in the dorsomedial MGRF. Quantitative analysis of the vacuolization showed that the total area and number of vacuoles in the MGRF increased with age, and they were affected by the degree of deficits in learning and memory. The latency 24 h after footshock in passive avoidance tests decreased with the increase in total area and number of vacuoles in MGRF. The number of shocks in active avoidance tests increased with the increase in total number and area of vacuoles. Thus, learning and memory ability in passive and active avoidance responses deteriorated with enlargement in the vacuolated area in MGRF, and it was assumed that MGRF (especially, the dorsomedial part) possesses functions related to learning and memory. To confirm this notion, behavior and memory tests (passive avoidance and active avoidance tests, open field tests and shock sensitivity measurements) were carried out in SAMR1 mice, whose bilateral dorsomedial MGRF was destroyed electrolytically (MGRF-lesioned mice). The MGRF-lesioned mice showed no difference from sham mice in sensory threshold or open field activity; however, there was severe deterioration in passive avoidance behavior and impairment in the active avoidance performances. From the results in SAMP8 and MGRF-lesioned mice, it was confirmed that MGRF (especially the dorsomedial part) has functions related to learning and memory, and is one part in the learning and memory system of the brain. Thus, SAMP8 can serve as a model of RF-lesioned mice with impaired learning and memory functions.

Aging↗
PubMed1998

Synthesis of a new class of camptothecin derivatives, the long-chain fatty acid esters of 10-hydroxycamptothecin, as a potent prodrug candidate, and their in vitro metabolic conversion by carboxylesterases.

Five (20S)-10-hydroxycamptothecin derivatives carrying the long-chain fatty acid esters were prepared for the development of a new class of prodrug-type agents. In vitro experiments using three kinds of purified carboxylesterase isozymes from the liver microsomes of rat, pig, and human demonstrated that these derivatives were efficiently metabolized by enzymes compared with CPT-11.

Animals↗
PubMed1998

[Clinical evaluation of Dumon stent for tracheobronchial stenosis due to advanced esophageal carcinoma].

We inserted Dumon stent to 13 patients with tracheobronchial stenosis due to advanced or recurrent esophageal carcinoma. Severe dyspnea was improved in 11 patients except for 2 patients with bilateral recurrent nerve palsy. 3 cases who had radiation therapy or chemotherapy lived over 150 days. We inserted esophageal stent in 4 cases. 2 patients died due to hemoptysis after 156 days and 35 days. We conclude that Dumon stent is one of the useful treatments in order to improve quality of life and prognosis of advanced or recurrent esophageal carcinoma.

Aged↗
PubMed1998

Polysaccharide K induces Mn superoxide dismutase (Mn-SOD) in tumor tissues and inhibits malignant progression of QR-32 tumor cells: possible roles of interferon alpha, tumor necrosis factor alpha and transforming growth factor beta in Mn-SOD induction by polysaccharide K.

Previously we reported the malignant progression of QR-32, a regressor-type tumor clone, following co-implantation with foreign bodies (gelatin sponge or plastic plate) in normal syngeneic C57BL/6 mice. We also reported that the progression of QR-32 cells by a gelatin sponge was significantly inhibited in the mice administered polysaccharide K (PSK) and that PSK induced an increase of radical scavengers, especially manganese superoxide dismutase (Mn-SOD), locally at the site of tumor tissues. In this study, to reveal the possible mechanism by which PSK induced Mn-SOD in the tumor tissues, we examined the mRNA expression and protein levels of inflammatory cytokines in the tissues. We found that mRNAs of tumor necrosis factor alpha (TNFalpha) and interleukin-1alpha (IL-1alpha) were considerably expressed in both PSK-treated and phosphate-buffered-saline-treated tumors, and that the mRNA expression and protein level of interferon gamma (IFNgamma) increased in the tumor tissues treated with PSK. In vitro treatment of QR-32 cells with IFNgamma did not significantly increase the production of Mn-SOD; however, the combination of IFNgamma with TNFalpha increased the Mn-SOD production more effectively than did any of the cytokines used singly. Furthermore, we observed the down-regulation of the mRNA expression and protein level of transforming growth factor beta (TGFbeta) in the tumor tissues treated with PSK, and that in vitro treatment of QR-32 cells with TGFbeta decreased the production of Mn-SOD. These results suggest that PSK suppresses the progression of QR-32 cells by increasing Mn-SOD via the modulation of inflammatory cytokines; that is, by decreasing TGF-beta and increasing IFN-gamma.

Adjuvants, Immunologic↗
PubMed1998

Ultrastructural and permeability features of microvessels in the olfactory bulbs of SAM mice.

The ultrastructural features of microvessels showing increased permeability to intravenously injected horseradish peroxidase (HRP) were examined in the olfactory bulbs of senescence-accelerated prone mice (SAMP8), which showed age-related deficits in learning and memory, and senescence-accelerated resistant mice (SAMR1), which did not show the age-related deficits. HRP was visualized with tetramethyl benzidine (TMB) and diaminobenzidine (DAB) for light and electron microscopic examination, respectively. In the olfactory bulbs of 13-month-old SAMP8 mice, the staining reaction with TMB for HRP appeared in the neuropil of central area (granule cell layer and subependymal layer), in the pia mater and in the vascular wall. Some vessels located in the central area showed several changes observed at the ultrastructural level. The cytoplasm of the endothelial cells, especially in the arterioles, was segmentally thickened and contained numerous vesicles and vacuoles, some of which were HRP positive. The endothelial cell surface was occasionally undulated with microvillous protrusions. Membranous inclusions within the basal lamina, suggesting the cellular (presumably pericytal) degeneration, were frequently observed, especially in venules. The collagen deposits were occasionally observed in the subendothelial space of some vessels. Perivascular cells with vacuolated inclusions or lipid-like droplets were present around some vessels in the central area of the olfactory bulbs of aged SAMP8 mice. On the other hand, in the microvessels located in the areas negative for HRP-TMB reaction, except the vessel walls, the cytoplasm of the endothelial cells with smooth luminal surface was flattened and some vesicles located there contained HRP-DAB reaction product. Weak staining reaction with TMB for HRP appeared also in the central area of the olfactory bulbs of 3-month-old SAMP8 mice and 3- and 13-month-old SAMR1 mice. The cytoplasm of the endothelial cells in the olfactory bulbs of these mice was focally thickened and contained some cytoplasmic vesicles. Occasionally, the endothelial cell surface was moderately undulated with few microvillous protrusions. Membranous inclusions within the basal lamina were not observed in these animals. These findings indicate that the endothelial cells and pericytes in some vessels located in the central area of the olfactory bulb of aged SAMP8 mice, which show staining reaction with TMB for HRP, are ultrastructurally changed, suggesting their altered functions.

Age Factors↗
PubMed1998

Effect of adrenomedullin on ion transport and muscle contraction in rat distal colon.

We have investigated the effects of adrenomedullin (AM) on mucosal ion transport using the Ussing method and smooth muscle contraction using the Magnus method in rat. Our results indicate that AM increases Isc (short-circuit current) for Cl- secretion (100 nM:170.0 +/- 41.2%, 1 microM:193.8 +/- 45.5%, 100% Isc:28.2 +/- 3.1 microA/cm2) with an initial small decrease of Isc, inhibiting Na+ absorption. Tetrodotoxin (TTX) inhibits the Isc response elicited by AM (86%). In addition, AM relaxes potassium-induced contraction (10 nM:11.1 +/- 8.51%, 100 nM:33.4 +/- 12.7%, 100% contraction: 1.8 +/- 0.22 g), and TTX inhibits the response elicited by AM (90%). We conclude that AM modulates water and ion transport as well as bowel movement, mainly through the colonic nervous system.

Adrenomedullin↗
PubMed1998

Characterization of the progressive sublines derived from a weakly malignant cloned cell line, ER-1, co-inoculated subcutaneously with a foreign body.

We previously established an experimental model of tumor progression using a weakly malignant rat mammary carcinoma cell line, ER-1. Using this model, we demonstrated that ER-1 cells converted into highly tumorigenic and metastatic cells, ERpP, by s.c. co-inoculation with plastic plates. We here compared in vitro biological properties associated with malignancy of ER-1 cells with those of ERpP cells which were highly malignant when inoculated into syngeneic rats. In vitro growth rate of ERpP cells was higher than that of ER-1 cells under a low nutrient condition. Invasion capacity of ERpP cells to rat lung endothelial cell monolayer or reconstituted basement membrane, Matrigel, was higher than that of ER-1 cells. Migration of ERpP cells toward fibronectin or laminin was also significantly higher than that of ER-1 cells. There was no difference in gelatinolytic or plasminogen activator activity detected in conditioned media between ER-1 and ERpP cells. Furthermore, we found that ER-1 cells communicated better among themselves and with normal fibroblasts through gap junctions compared to ERpP cells. These results suggest that growth advantage in a poor nutrient condition, enhancement of cell motility, and loss or decrease of junctional communication may be associated with tumor progression of ER-1 cells.

Animals↗
PubMed1998

Effects of okadaic acid on rat colon.

Effects of okadaic acid (OA) on mucosal damage were examined in rat colon. OA was sprinkled on rat colon mucosa under observation with an electronic-endoscopic system, and OA was also applied to the in vivo microscopic field. The OA-induced changes in transepithelial conductance (Gt) were measured by the Ussing voltage clamp technique. By endoscopic observation, the luminal sprinkling of OA (60 nmol/kg) evoked transient microthrombi in the submucosal venule, which was followed by mucosal edema. Histological study after endoscopic observation showed submucosal fluid retention, suggesting an increase of vascular permeability. The microthrombi were also detected by in vivo microscopy. By electrophysiological study after endoscopic observation with and without OA addition, the basal Gt values were 54+/-6.2 and 36.2+/-4.2 mS/cm2, respectively (P < 0.01). Furthermore in control rats, the serosal addition of OA evoked an increase in Gt in a concentration-dependent manner without increasing lactate dehydrogenase release. 2,4,6-Triaminopyrimidinium inhibited OA-induced Gt change by 60%. These results indicate that OA evokes an increase in paracellular permeability of epithelium. We conclude that the developed microthrombi are the first key event of OA-induced mucosal damage, followed by an increase in permeability in the submucosal venule and in the paracellular pathway of the epithelium.

Animals↗
PubMed1998

Inhibitory effects of malotilate on invasion and metastasis of rat mammary carcinoma cells by modifying the functions of vascular endothelial cells.

Malotilate (diisopropyl,1,3-dithiol-2-ylidenemalonate, MT) is clinically used as a hepatoprotective agent. Because we noticed that MT induced the differentiation of cultured vascular endothelial cells, we have examined its effects on lung metastasis of the highly metastatic rat mammary carcinoma c-SST-2. MT was orally administered to syngeneic SHR rats from 7 days before or after s.c. inoculation of c-SST-2 cells to the end of the experiments. In the MT-treated rats, pulmonary metastasis was markedly suppressed compared with the non-treated rats. In the rats treated with MT for 19 days after i.v. inoculation of c-SST-2 cells, lung metastasis was also significantly suppressed. An in vitro invasion assay using a rat lung endothelial (RLE) cell monolayer revealed that pretreatment of the RLE cells with MT, but not c-SST-2 cells, significantly reduced the invasion of the RLE monolayer by c-SST-2 cells. An in vitro vascular permeability assay demonstrated that MT prevented the increase in permeability of the RLE monolayer by serum starvation. On the other hand, in vivo and in vitro growth, gelatinase production and adhesion to the RLE cell monolayer of c-SST-2 cells were not affected by MT treatment. These findings suggest that MT suppressed tumour metastasis by intensifying the cell-to-cell contact of endothelial cells, thus preventing tumour cells from invading vascular endothelium.

Animals↗
PubMed1998

Protein kinase C mediates the signal for interferon-gamma mRNA expression in cytotoxic T cells after their adhesion to laminin.

A cytotoxic T-cell line, CTLL-2 cells, showed spreading after adhering to extracellular matrix proteins such as fibronectin (FN), laminin (LN) and hyarulonic acid (HA). The adhesion of CTLL-2 cells to LN was mediated by very late activation antigen-6 (VLA-6). Expression of interferon-gamma (IFN-gamma) mRNA was enhanced in CTLL-2 cells, also when they adhered to extracellular matrix proteins; and the enhanced IFN-gamma mRNA expression by adhering to LN was blocked by anti-alpha 6 antibody. Calphostin C, a protein kinase C (PKC) inhibitor, markedly inhibited the enhancement of IFN-gamma mRNA expression in a dose-dependent manner, which suggested that PKC acted as a second messenger in the IFN-gamma mRNA expression mediated by the interaction of VLA-6 with LN in CTLL-2 cells. Furthermore, confocal laser-microscopic analysis and Western blot analysis revealed that PKC-alpha was activated after CTLL-2 cells adhered to LN. PKC activity translocated from the cytosol fraction to the particulate fraction, after CTLL-2 cells adhered to LN. Altogether, we suggest that PKC plays an important role in the signal transduction for IFN-gamma mRNA expression after cytotoxic T cells adhere to LN.

Animals↗
PubMed1998

Accelerated aging of dermal fibroblast-like cells from the senescence-accelerated mouse (SAM): acceleration of changes in DNA ploidy associated with in vitro cellular aging.

Accelerated changes in the DNA ploidy associated with in vitro aging were examined in fibroblast-like cells isolated from the dorsal dermis of newborn SAMP11 (accelerated senescence-prone, short-lived) mice, and were compared to changes observed in cell lines from SAMR1 (accelerated senescence-resistant, long-lived) mice. Flow cytometric analysis of the DNA content in confluent cells and chromosome analysis in mitoses revealed that the diploid cells were being replaced with tetraploid cells until a growth crisis; thereafter, hypotetraploid cells became predominant, accompanied by immortalization. The number of mitoses decreased as the crisis ensued, then increased. Although these changes were observed in the cell lines from both strains of mice, the changes occurred more rapidly and at earlier population doublings in the cell lines from the SAMP11 mice. These results suggest that the cell lines from SAMP11 mice might have higher susceptibility to factors that cause polyploidization, including oxidative stress.

Aging↗
PubMed1998

A new anti-metastatic drug, ND-2001, inhibits lung metastases in rat hepatoma cells by suppressing haptotaxis of tumor cells toward laminin.

We examined the effects of ex vivo treatment of tumor cells with sodium D-glucaro-delta-lactam (sodium 5-amino-5-deoxy-D-glucosaccharic acid-delta-lactam; ND-2001). The ex vivo treatment of rat hepatoma cKDH-8/11 cells with this new synthetic product of the antibiotic nojirimycin, ND-2001 (50 microg/ml), inhibited the experimentally induced lung metastases of the tumor cells significantly at an inhibition rate of 69.2% (one of 10 animals remained metastasis free). Also, it was elucidated in in vitro tumor cell invasion assays that ND-2001 (50 microg/ml) suppressed the invasion activities of cKDH-8/11 cells to Matrigel Matrix at an inhibition rate of 69.3%. However, phagokinetic track assays revealed that ND-2001 did not suppress the random motility of cKDH-8/11 cells. However, ND-2001 (50 microg/ml) suppressed the haptotaxis, another important role in tumor invasion, of cKDH-8/11 cells toward laminin (inhibition rate of 77.0%). These results suggest that ND-2001 suppressed the haptotaxis of tumor cells toward laminin directly at the step of invading the basement membrane and brought about the inhibition of lung metastases.

Animals↗
PubMed1998

ONO-4007 induces specific anti-tumor immunity mediated by tumor necrosis factor-alpha.

We investigated the therapeutic effects of ONO-4007, a novel synthetic lipid A derivative with low toxic activities, on transplanted hepatocellular carcinoma KDH-8 in WKAH rats. ONO-4007 brought about complete cures in about 60% of rats bearing tumor necrosis factor (TNF)-alpha-sensitive KDH-8 cells, whereas no complete cure was observed in rats bearing cKDH-8/11 which is identical to KDH-8 but a TNF-alpha-resistant cell line, KMT-17 and KEG-1. Then we examined the influence of rabbit anti-TNF-alpha antibody on the therapeutic effects of ONO-4007 against the TNF-alpha-sensitive KDH-8. The concomitant administration of the rabbit anti-TNF-alpha antibody completely abrogated the therapeutic effects of ONO-4007. On the other hand, rechallenged tumor cells of both KDH-8 and cKDH-8/11 were completely rejected in the rats cured of KDH-8 tumor, although no rejection of KEG-1 was observed. Moreover, Winn assay, i.e. the tumor cell neutralizing assay, indicated that CD4+ T cells were involved in the antigen-specific transplantation resistance. These findings suggest that antigen-specific T cell responses are involved in the complete cure of tumors after the treatment with ONO-4007, although its therapeutic effect is initiated by TNF-alpha.

Animals↗
PubMed1998

Combination therapy of active hexose correlated compound plus UFT significantly reduces the metastasis of rat mammary adenocarcinoma.

Synergistic effects of active hexose correlated compound (AHCC) extracted from mushroom on the treatment with UFT against mammary adenocarcinoma, SST-2 cells, in congenitally T cell-depressed spontaneously hypertensive rats (SHR) were observed. AHCC plus UFT had slight but significant effects on the growth of primary tumors. Pulmonary metastases were not inhibited by the treatment with AHCC plus UFT, whereas metastases to axillary lymph nodes (LN) were obviously inhibited. Combination of AHCC plus UFT showed similar synergistic anti-metastatic effects in SHR rats with accelerated pulmonary metastases following the surgical removal of the primary tumors. In vitro studies demonstrated that AHCC plus UFT enhanced the NK cell activity in tumor-bearing rats, whereas UFT alone depressed the NK cell activity. AHCC plus UFT also enhanced the NO production and cytotoxicity of peritoneal macrophages. In addition, AHCC restored the suppressed mRNA expression of interleukin-1alpha and tumor necrosis factor-alpha induced by the chemotherapy. Taken together, the combination of AHCC plus UFT brought about good therapeutic effects not only on primary tumor growth but also on reducing metastasis and these effects were mediated by host immunity which was restored or activated by AHCC. AHCC may be a good candidate for a biological response modifier.

Adenocarcinoma↗
PubMed1998

ND-2001 suppresses lung metastasis of human renal cancer cells in athymic mice.

Explants of highly metastatic human renal cell carcinoma SN12Cpm6 cells in athymic mice were treated with sodium D-glucaro-delta-lactam (sodium 5-amino-5-deoxy-D-glucosaccharic acid-delta-lactam; ND-2001). ND-2001 (50 micrograms/ml) caused 78% inhibition of lung metastasis of SN12Cpm6 cells (two of five animals remaining metastasis free). The in vitro tumor cell invasion assay showed that ND-2001 (100 micrograms/ml) suppressed the invasive activity of SN12Cpm6 cells to Matrigel matrix at an inhibition rate of 72%. These results suggest that ND-2001 may be a new anti-metastatic drug against human cancer cells.

Animals↗