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Biomedical subjects

Y Tamada

Publications and source records attributed to Y Tamada.

At least 19 recordsLinked to original sources
PubMed2006

Amelioration of retinal degeneration and proteolysis in acute ocular hypertensive rats by calpain inhibitor ((1S)-1-((((1S)-1-benzyl-3-cyclopropylamino-2,3-di-oxopropyl)amino)carbonyl)-3-methylbutyl)carbamic acid 5-methoxy-3-oxapentyl ester.

BACKGROUND: Our recent study suggested involvement of calpain-induced proteolysis in retinal degeneration and dysfunction in acute ocular hypertensive rats. The purpose of the present study was to determine if an orally available form of calpain inhibitor, ((1S)-1-((((1S)-1-benzyl-3-cyclopropylamino-2,3-di-oxopropyl)amino)carbonyl)-3-methylbutyl)carbamic acid 5-methoxy-3-oxapentyl ester (SNJ-1945), ameliorated retinal degeneration induced by acute hypertension in rats. To help extrapolate the effect of SNJ-1945 from the rat model to the human glaucomatous patient, in vitro inhibition of calpain-induced proteolysis by SNJ-1945 in monkey and human retinal proteins was compared with proteolysis in rat proteins. METHODS: Intraocular pressure (IOP) in rats was elevated to 110 mm Hg for 50 min. SNJ-1945 was administrated i.p. or orally before ocular hypertension. Retinal degeneration was evaluated by hematoxylin and eosin (H&E) staining and cell counting. Transcripts for calpains and calpastatin in rat, monkey, and human retinas were measured by quantitative RT-PCR. Calpain activities were determined by casein zymography. Soluble retinal proteins from rat, monkey, and humans were incubated with calcium to activate calpains, with or without SNJ-1945. Proteolysis of calpain substrate alpha-spectrin was analyzed by immunoblotting. RESULTS: Elevated IOP caused retinal degeneration and proteolysis of alpha-spectrin. Both i.p. and oral administration of SNJ-1945 inhibited proteolysis of alpha-spectrin and ameliorated retinal degeneration. Transcript levels for calpain 1 and calpastatin were similar in rat, monkey, and human retinas. Calpain 2 transcript levels were higher in rats compared with monkey and human. Appreciable caseinolytic activities due to calpains were observed in monkey and human retinas. Incubation of retinal soluble proteins with calcium led to proteolysis of alpha-spectrin due to calpains in rat, monkey, and human samples. SNJ-1945 similarly inhibited proteolysis in all species. CONCLUSION: Our results suggested that orally available calpain inhibitor SNJ-1945 might be a possible candidate drug for testing in preventing progression of glaucomatous retinal degeneration.

Animals↗
PubMed2006

Analysis of gene mutations in four cases of dermatofibrosarcoma protuberans.

Fusion of the collagen type I alpha 1 (COL1A1) gene with the platelet-derived growth factor B-chain (PDGFB) gene has been described in dermatofibrosarcoma protuberans (DFSP). Various exons of the COL1A1 gene have been shown to be involved in the fusion with exon 2 of the PDGFB gene. We examined the breakpoints of the COL1A1 gene using the tumour specimens from four patients with DFSP. The COL1A1-PDGFB fusion transcripts were detected from the cultured tumour cells by reverse transcriptase polymerase chain reaction. Sequence analysis revealed that the ends of exons 23, 25, 26 and 36 in the COL1A1 gene were fused with the start of exon 2 in the PDGFB. This study identified three novel COL1A1 breakpoints: exons 23, 26 and 36 of the COL1A1 gene. In one case, the tumour was composed of two areas that differed in cytological atypia, cellularity and mitotic activity, indicating the dedifferentiation of the tumour. In tumour cells from two different areas the same aberrant fusion transcripts were identified. These results suggest that the dedifferentiation of tumour cells has nothing to do with the specific breakpoints of the COL1A1 gene, but depends on other unknown factors.

Adult↗
PubMed2004

Model for paraaortic lymph node metastasis produced by orthotopic implantation of ovarian carcinoma cells in athymic nude mice.

Lymph node metastasis through the lymphatic vessels is a critical step in determining the outcome of ovarian cancer patients, and prognosis should be improved by preventing lymph node metastasis. However, experimental models for lymph node metastasis of ovarian carcinoma are not available. We developed an orthotopic transplantation model to study this process in nude mice using the human ovarian carcinoma cell lines, KF and MH. Highly metastatic sublines (KF-LN3 and MH-LN3) were selected in vivo in nude mice by repeated orthotopic transplantation, lymph node metastasis formation and culturing the tumour cells in vitro. Because this model seems to correspond to the advanced clinical stage of ovarian carcinomas, it should be useful in understanding the molecular biology of ovarian carcinomas and in the development of therapeutic modalities against lymph node metastasis.

Animals↗
PubMed2004

Cyclooxygenase-2 is a possible target of treatment approach in conjunction with photodynamic therapy for various disorders in skin and oral cavity.

BACKGROUND: Anti-cancer effects of cyclooxygenase (COX)-2 inhibitors have been reported, but not fully investigated in skin and oral diseases. 5-aminolaevulinic acid (ALA)-based photodynamic therapy (PDT) for treating those patients with skin and oral lesions is a highly sophisticated procedure, but the incidence of disease recurrence after treatment is rather significant. OBJECTIVE: To confirm that COX-2 could be a molecular target in adjunctive therapy to ALA-based PDT, we investigated (i) COX-2 expression in various skin and oral diseases, and (ii) the inhibitory effects on cellular growth of COX-2 selective inhibitor (nimesulide), ALA-based PDT and their combination on human oral squamous cell carcinoma (SCC) cell lines. METHODS: A total of 129 biopsy samples from the skin and oral mucosal lesions were tested immunohistochemically for COX-2 expression. Then the in vitro effects of nimesulide, ALA-based PDT, and their combination were determined on two SCC cell lines, HSC-2 and HSC-4. Three different methods (MTT assay, double-staining for annexin V and propidium iodide, caspase-3/CPP32 fluorometric protease assay) were applied for evaluation of their inhibitory effects on these two cell lines. RESULTS: Among the skin diseases, a considerable number of COX-2 high expressers were found in actinic keratosis (15 of 25, 60%), Bowen's disease (13 of 17, 76%) and extramammary Paget's disease (15 of 15, 100%). In contrast, only one of 33 (3%) basal cell carcinoma tumours was a COX-2 high expresser. Among the oral mucosal biopsies, the proportion of COX-2 high expressers increased gradually from hyperplasia (one of six, 17%) through mild dysplasia (five of eight, 63%) and moderate dysplasia (20 of 23, 87%) to severe dysplasia (two of two, 100%). Nimesulide had an inhibitory effect in vitro on HSC-2 (proven to be a COX-2 high expresser), but not on HSC-4 (a COX-2 non-expresser). While ALA-based PDT showed an inhibitory effect on both HSC-2 and HSC-4, most importantly the combination of nimesulide and ALA-based PDT demonstrated a significant synergistic effect on the cellular growth inhibition of only HSC-2, but not of HSC-4. CONCLUSIONS: Our study strongly suggests that COX-2 can be one of the molecular targets in treating various skin and oral diseases. The results from our in vitro experiments also prompt us to develop a new protocol with a combination of COX-2 selective inhibitor and ALA-based PDT for more effective treatment of those diseases.

Aminolevulinic Acid↗
PubMed2003

Histological changes and involvement of apoptosis after photodynamic therapy for actinic keratoses.

BACKGROUND: Photodynamic therapy (PDT), which employs a combination of a tumour-localizing photosensitizer and visible light, has been used to treat superficial malignancies in the epidermis. OBJECTIVES: To examine histological changes and the role of apoptosis in lesions of actinic keratosis (AK) after PDT using 5-aminolaevulinic acid (ALA) and excimer dye laser. METHODS: After topical ALA-PDT, biopsy specimens were collected from 18 skin lesions in 15 patients with AK. Paraffin-embedded sections of the skin specimens were stained with haematoxylin and eosin. The detection of apoptosis was performed using a terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labelling (TUNEL) method, antiactivated caspase-3 antibody and anti-Fas antibody. RESULTS: One hour after PDT, cells with eosinophilic cytoplasm and markedly stained nuclei were found, and vacuolation of some tumour cells was noted in the lower layer of the epidermis. An infiltrate of lymphocytes and neutrophils was observed in the upper layer of the dermis. One day after PDT, all layers of the epidermis exhibited slightly degenerative necrosis, with shadow cell formation and chromatin condensation around the nuclear membrane in the lower layer of the epidermis. Necrosis in all layers of the epidermis and lymphocyte infiltration in the dermis were found 3 days after PDT. Tumour cells had disappeared and regenerative thickening of the epidermis was observed 7 days after PDT. TUNEL staining revealed apoptosis-positive cells in the epidermis in 8 of 11 specimens obtained 1 day after PDT. Activated caspase-3 expression was noted in the lower layer of the epidermis in four of these eight TUNEL-positive specimens. CONCLUSIONS: Results suggested that apoptosis is involved in tumour cell death after PDT in patients with AK, and that it occurs within 1 day after PDT.

Aged↗
PubMed2003

Intrasplicing--analysis of long intron sequences.

We propose a new model for the splicing of long introns, which we call intrasplicing. The basic idea of this model is that the splicing of long introns may be facilitated by the splicing of inner parts of the intron prior to the splicing of the long intron itself. Since long introns have up to about 100,000 bases, this model seems to be a likely explanation of their splicing. To investigate the possibility of this model, we develop a new computational method for the analysis of DNA sequences with respect to splicing. We analyze the genomic sequence of four species with our method and derive several results indicating that intrasplicing may be an appropriate model for the splicing of at least part of the long intron sequences.

Animals↗
PubMed2001

RET tyrosine kinase enhances hair growth in association with promotion of melanogenesis.

We first demonstrated that c-Ret protein is transiently expressed mainly in the inner and outer root sheaths of hair follicles soon after birth in the skin of normal C57BL/6 and BALB/c mice. A longer-lasting expression of activated RET protein overlapped the c-Ret expression with some preferential expression in the outer root sheath in close association with increase in the number of S-100 protein-containing cells in the area and excess melanogenesis in and around hair bulbs in the skin of RFP-RET-transgenic mice on a C57BL/6 background (RFP-RET/B6). Hair follicles in the skin of the transgenic mice continuously showed histology of the anagen phase, and the recovery period for the hair of the transgenic mice after shaving was shortened. Such growth promotion was not observed in the case of white hairs of RFP-RET-transgenic mice on a BALB/c background. These results suggest that RET works to extend the anagen phase in association with upregulation of melanin production.

Aged↗
PubMed2001

Serotonin modulates expression of VIP and GRP mRNA via the 5-HT(1B) receptor in the suprachiasmatic nucleus of the rat.

The expression of vasoactive intestinal peptide (VIP) and gastrin-releasing peptide (GRP) in the suprachiasmatic nucleus (SCN) changes depending on light. VIP mRNA increases and GRP mRNA decreases in the light phase, while they do not show change without light. In the present study we investigated the involvement of serotonin (5-HT) in the expression of VIP and GRP messenger RNA in the SCN of the rat. The decrease in VIP mRNA and the increase in GRP mRNA in the light phase were amplified by 5-HT depletion using 5,6-dihydroxytryptamine injected into the lateral ventricle. These enhancements due to 5-HT depletion were reversed to control levels by applying 5-HT(1B) agonists TFMPP and CGS12066A, but not a 5-HT(1A)/5-HT(7) agonist, 8-OH-DPAT. The 5-HT(1B) receptor is known to exist on the terminals of the retinohypothalamic tract (RHT). Therefore, next we investigated the morphological relationship of RHT and 5-HT terminals by double-labeling immunocytochemistry and demonstrated that 5-HT-immunoreactive fibers and cholera toxin B subunit-labeled RHT terminals were intermingled in the ventrolateral SCN, and 5-HT axon processes had close contact with RHT terminals. Collectively, these pharmacological and morphological results suggest that 5-HT afferents from raphe nuclei modulate VIP and GRP expression in neurons of the ventrolateral SCN by activating the 5-HT(1B) receptor in the RHT.

5,6-Dihydroxytryptamine↗
PubMed2001

Calpain inhibitor, SJA6017, reduces the rate of formation of selenite cataract in rats.

PURPOSE: 1) To measure the amount of calpain inhibitor SJA6017 taken up by lenses of young rats after administration; and 2) To test efficacy of SJA6017 against selenite cataract in regard to amelioration of proteolysis of lens protein and prevention of lens nuclear opacity. METHODS: Selenite nuclear cataracts were produced by subcutaneous injection of an overdose of sodium selenite to 16-day-old rats. SJA6017 was administered daily using intraperitoneal injections at 100 mg/kg body weight/day for 4 days. Lenses were observed and photographed by slit lamp biomicroscopy, and scored into one of three stages. Enucleated lenses were also scored into one of four stages and lens opacities in the nuclear region were quantified by image analysis. Proteolysis of crystallins was detected by SDS-PAGE. The amount of SJA6017 taken up by the lens was detected with a column switching HPLC system. RESULTS: Nuclear cataracts were visible in 31% of the animals receiving only selenite, while the frequency of nuclear cataract in the Se+SJA6017 group was reduced to only 16%. This effect of SJA6017 was confirmed by densitometric analysis as a reduction in the density of the nucleus. Similar proteolytic changes of crystallins occurred at all stages of selenite cataract formation. The amount of SJA6017 in the lens was detected at the level of 0.03 microM. CONCLUSIONS: Systemic SJA6017 was taken up by the lens, and SJA6017 ameliorated in vivo selenite cataract formation. These studies are important because they partially validate the biochemical rationale for developing non-surgical, drug treatments for cataract prevention in man.

Animals↗
PubMed2001

Intraocular pressure-lowering efficacy of latanoprost in patients with normal-tension glaucoma or primary open-angle glaucoma.

We investigated the intraocular pressure (IOP)-lowering potential of latanoprost in patients with normal-tension glaucoma (NTG) or primary open-angle glaucoma (POAG). This prospective study included 59 NTG and 20 POAG patients treated with the following four dosing regimens of latanoprost: patients on no previous medication received latanoprost as initial therapy (Group 1, n=31), patients on beta-blocker therapy received latanoprost as adjunctive therapy (Group II, n=9), patients on unoprostone monotherapy were switched to latanoprost monotherapy (Group III, n=14), and patients previously on dual therapy with isopropyl unoprostone and beta-blocker were switched to a combined treatment of latanoprost and beta-blocker (Group IV, n=25). IOP significantly decreased 8 weeks after initiation of latanoprost therapy by 19.9% in Group I, 20.5% in Group II, 16.6% in Group III, and 12.2% in Group IV. In Groups I and II, there was a significant positive correlation between the magnitude of IOP reduction induced by latanoprost and the IOP level before latanoprost therapy. The IOP level before latanoprost therapy is a contributing factor in the IOP-lowering efficacy of latanoprost. Latanoprost is more effective in lowering IOP than isopropyl unoprostone.

Adrenergic beta-Antagonists↗
PubMed2001

Molecular typing and epidemiological study of Salmonella enterica serotype Typhimurium isolates from cattle by fluorescent amplified-fragment length polymorphism fingerprinting and pulsed-field gel electrophoresis.

One hundred twenty Salmonella enterica serotype Typhimurium strains, including 103 isolates from cattle gathered between 1977 and 1999 in the prefecture located on the northern-most island of Japan, were analyzed by using fluorescent amplified-fragment length polymorphism (FAFLP) and pulsed-field gel electrophoresis (PFGE) to examine the genotypic basis of the epidemic. Among these strains, there were 17 FAFLP profiles that formed four distinct clusters (A, B, C, and D). Isolates that belonged to cluster A have become increasingly common since 1992 with the increase of bovine salmonellosis caused by serotype Typhimurium. PFGE resolved 25 banding patterns that formed three distinct clusters (I, II, and III). All the isolates that belonged to FAFLP cluster A, in which all the strains of definitive phage type 104 examined were included, were grouped into PFGE cluster I. Taken together, these results indicate that clonal exchange of serotype Typhimurium has taken place since 1992, and they show a remarkable degree of homogeneity at a molecular level among contemporary isolates from cattle in this region. Moreover, we have sequenced two kinds of FAFLP markers, 142-bp and 132-bp fragments, which were identified as a polymorphic marker of strains that belonged to clusters A and C, respectively. The sequence of the 142-bp fragment shows homology with a segment of P22 phage, and that of the 132-bp fragment shows homology with a segment of traG, which is an F plasmid conjugation gene. FAFLP is apparently as well suited for epidemiological typing of serotype Typhimurium as is PFGE, and FAFLP can provide a source of molecular markers useful for studies of genetic variation in natural populations of serotype Typhimurium.

Animals↗
PubMed2001

Impaired distensibility of the left ventricle after stiffening of the right ventricle.

Acute and chronic alterations of right ventricular (RV) wall properties can change left ventricular (LV) performance. We investigated whether and how stiffening of the RV free wall alters LV diastolic distensibility. We used cross-circulated isolated hearts, in which the LV and RV were independently controllable. Stiffness of the RV free wall was altered by intramuscular injections of glutaraldehyde into the RV free wall after right coronary artery ligation. We measured circumferential and longitudinal regional lengths in the septum and LV free wall. During data acquisition, RV volume was held constant. After the RV free wall was stiffened by glutaraldehyde, the LV diastolic pressure-volume relation shifted upward and became steeper. Importantly, stiffening of the RV free wall increased the diastolic regional area in the septum and LV free wall under constant LV volume. The augmented regional dimensions may result in enhanced regional tension under constant LV volume and may be related to the observed increase in LV diastolic intracavitary pressure. The impaired LV diastolic distensibility by stiffening of the RV free wall may be at least partly explained by myocardial stretch, probably due to LV deformation.

Animals↗
PubMed2001

A novel function of prolactin-releasing peptide in the control of growth hormone via secretion of somatostatin from the hypothalamus.

The present study examined a novel function of PRL-releasing peptide (PrRP) on the neuroendocrine. PrRP-immunoreactive nerve fibers and nerve terminals were located in the vicinity of the somatostatin (SOM)-neurons in the hypothalamic periventricular nucleus (PerVN). Immuno-electron microscopy revealed that PrRP-immunoreactive nerve terminals made synaptic contacts with nonimmunoreactive neuronal elements in the PerVN. Intracerebroventricular (icv) administration of PrRP induced immediate early gene, NGFI-A, in SOM-neurons in the PerVN. Double-labeling in situ hybridization showed that some parts of SOM-neurons in the PerVN expressed PrRP receptor messenger RNA. Therefore, some parts of SOM-neurons in the PerVN are considered to be directly innervated by PrRP via PrRP receptor. In addition to the above morphological characteristics, icv administration of PrRP decreased plasma GH levels. Such inhibitory effects of PrRP on the secretion of GH from the anterior pituitary were diminished by depletion or neutralization of SOM. From these findings it was strongly suggested that SOM-neurons respond to PrRP and secrete SOM into the portal vessels and thus inhibit GH secretion from the anterior pituitary.

Animals↗
PubMed2001

Alteration of apoptosis in cleft palate formation and ectomesenchymal stem cells influenced by retinoic acid.

It has been shown that apoptosis is involved in normal embryonic development. The aim of the present study was to elucidate the role and alteration of apoptosis in the pathogenesis of cleft palate induced by retinoic acid (RA) and the ectomesenchymal stem (EMS) cells influenced by RA. RA was administered by gavage to pregnant C57BL/6N strain mice in the experimental group, and the control group received oil alone. Pregnant mice were killed at set periods of time thereafter and histologically analyzed. EMS cells explanted from the palatal shelves of embryonic mice were cultured and characterized by immunohistochemistry, growth curves and population-doubling time. The alterations of apoptosis of EMS cells and developing palatal shelves influenced by RA were evaluated by the terminal deoxynucleotidyl transferase-mediated UTP-biotin nick end-labeling (TUNEL) method. RA-treated mice showed formation of cleft palates resulted from the small size of the palatal shelves and their failure to lift. TUNEL staining showed that the number of apoptotic mesenchymal cells in palatal shelves in the RA-treated mice was increased significantly when compared with the control group. The primary culture of EMS cells proceeded successfully. The population-doubling time of RA-treated cells was much longer compared with non-treated EMS cells. RA also dramatically increased the number of apoptotic cells in EMS cells in vitro. We concluded that EMS cells are the crucial cells in palate development. RA could inhibit the proliferation and induced the apoptosis of EMS cells. The inhibition of growth and excess apoptosis of EMS cells may contribute to the formation of cleft palate and other orofacial congenital malformations.

Animals↗
PubMed2000

Evidence for apoptosis in the selenite rat model of cataract.

The purposes of this experiment were (1) to determine if apoptosis was accelerated during formation of selenite cataract, and (2) to determine the role of calpains and caspases in lens apoptosis. Evidence for apoptosis in selenite-injected rats included: approximately 7-8% of epithelial cells in germinative zone were positive, disappearance of the nuclear membrane, condensation of the chromatin, and breakdown of PARP. Activation of calpains was indicated by characteristic limited proteolysis of crystallins, breakdown of alpha-spectrin to 150/145 kDa fragments, hydrolysis of vimentin, and autolytic breakdown of m-calpain. Selenite cataract did not have an appreciable effect on the mRNA levels for caspase-3, calpains, and calpastatin. This indicated the increased enzyme activity of m-calpain and caspase-3 in selenite cataract occurred at the enzyme level rather than by upregulation of mRNAs. Increased calpain and caspase activity may be linked to the selenite-induced apoptosis. Such data are important because they indicate that apoptosis may be a fairly early event in selenite cataract.

Animals↗