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Biomedical subjects

M Osaki

Publications and source records attributed to M Osaki.

71 records · Page 4Linked to original sources
PubMed1996

Parathyroid hormone-related protein (PTHrP) action in rat articular chondrocytes: comparison of PTH(1-34), PTHrP(1-34), PTHrP(1-141), PTHrP(100-114) and antisense oligonucleotides against PTHrP.

Parathyroid hormone-related protein (PTHrP) is thought to be an important autocrine/paracrine factor for chondrocyte metabolism since mice lacking the PTHrP gene exhibit abnormal cartilage development. To determine the biological role of PTHrP in chondrocytes, we first compared the agonist potency of human (h) PTHrP(1-34) with hPTH(1-34) in cultured rat articular chondrocytes. Neither hPTHrP(1-34) nor hPTH(1-34) altered basal DNA synthesis, but attenuated the stimulatory effect of transforming growth factor beta (TGF-beta). Both agents suppressed the expression of alpha(1) type II collagen mRNA in a dose-response fashion with the same potency. In addition, the action of exogenously added hPTHrP(1-34) and hPTH(1-34) on intracellular cAMP and [Ca2+]i levels was similar. We next compared the effect of PTHrP within its entire amino acid sequence (1-141). With regard to thymidine incorporation, alpha(1) type II collagen gene expression and accumulation of cAMP and [Ca2+]i level, there was no significant difference between hPTHrP(1-34) and hPTHrP(1-141). PTHrP C-terminal (100-114) did not show any function. To further investigate PTHrP function, intracellular PTHrP translation was inhibited by a transgene of antisense oligonucleotides against PTHrP. Antisense oligonucleotides decreased PTHrP mRNA translation, specifically inhibited DNA synthesis in control as well as TGF-beta-treated chondrocytes and enhanced alpha(1) type II collagen mRNA expression in TGF-beta-treated chondrocytes. These results suggest that there is no significant difference between exogenously added hPTH(1-34), hPTHrP(1-34) and PTHrP(1-141) with regard to the biological action of these agents, including cell growth, differentiation and second messenger pathway. However, the result of DNA synthesis in the antisense PTHrP-inhibition study suggests that intracellular PTHrP may have an as yet unknown biological role, in addition to a classical PTH/PTHrP receptor-mediated function in the rat articular chondrocyte.

Animals↗
PubMed1995

Apoptosis in the human allografted kidney. Analysis by terminal deoxynucleotidyl transferase-mediated DUTP-botin nick end labeling.

Apoptosis is a distinct form of cell death and occurs under a variety of physiological and pathological conditions. This study was conducted to examine the occurrence of apoptotic cell death in 44 formalin-fixed, paraffin-embedded biopsy specimens from allografted kidneys by the terminal deoxynucleiotidyl transferase (TdT)-mediated D-UTP-biotin nick end labeling (TUNEL) method. Careful observation of routine hematoxylin and eosin sections revealed a few apoptotic cells in cortical tubules. TUNEL signal was detected variably in tubular epithelia, and occasionally in lymphocytic cells and endothelium. The number of tubular epithelia demonstrating TUNEL signals was highest for cyclosporine tubulopathy, followed by acute rejection of very mild or mild grade, and then by chronic allograft nephropathy. Protocol biopsies from normally functioning grafts showed the least apoptotic cells, with the number being significantly lower than that of both cyclosporine tubulopathy (P < 0.01) and acute rejection (P < 0.05). Two specimens of acute accelerated rejection with diffuse hemorrhagic necrosis showed nonspecific signals in a few epithelia. These findings suggest that acute rejection or cyclosporine nephropathy not infrequently induces apoptosis of tubular epithelia, which might lead to tubular atrophy or loss, resulting in chronic transplant nephropathy.

Adolescent↗
PubMed1989

Na+/H+ exchange modulates the production of leukotriene B4 by human neutrophils.

Human neutrophils produce various compounds of the 5-lipoxygenase pathway, including (5S)-hydroxyeicosatetraenoic acid, leukotriene B4, its 6-trans isomers and omega-oxidation metabolites of LTB4, when the cells are stimulated with the Ca2+ ionophore A23187. The elevation in the extracellular pH (pHo) facilitated the cytoplasmic alkalinization induced by the ionophore as determined fluorometrically using 2',7'-bis(carboxyethyl)carboxyfluorescein and enhanced the production of all the 5-lipoxygenase metabolites. The production decreased when the alkalinization was blocked by the decrease in the pHo, the removal of the extracellular Na+ or the addition of specific inhibitors of the Na+/H+ exchange, such as 5-(NN-hexamethylene)amiloride, 5-(N-methyl-N-isobutyl)amiloride and 5-(N-ethyl-N-isopropyl)amiloride. The alkalinization of the cytoplasm with methylamine completely restored the production suppressed by the removal of Na+ from the medium. These findings suggest that the change in the cytoplasmic pH (pHi) mediated by the Na+/H+ exchange regulates the production of the lipoxygenase metabolites. The site of the metabolism controlled by the pHi change seemed to be the 5-lipoxygenase, because the production of all the metabolites decreased in parallel and the release of [3H]arachidonic acid from the neutrophils in response to the ionophore was not affected by the pHi change. Furthermore, the production of the 5-lipoxygenase metabolites stimulated by A23187 with or without exogenous arachidonic acid showed a similar pHo-dependence and the production induced by N-formylmethionyl-leucylphenylalanine (chemotactic peptide) with exogenous arachidonic acid also decreased when the cytoplasmic alkalinization was inhibited.

Arachidonate 5-Lipoxygenase↗
PubMedDate not supplied

An outbreak of human Leishmania (Viannia) braziliensis infection.

The occurrence of acute cutaneous leishmaniasis among inhabitants of 10 farms within 10 Km of the hamlet of Corte de Pedra, Bahia, Brazil was studied prospectively from 1984-1989. A mean population of 1,056 inhabitants living in 146 houses were visited every 6 months and the number of skin ulcers recorded. A leishmanin skin test survey was done people with suggestive skin scars or active disease in 1984. The incidence of skin ulcers due to Leishmania (Viannia) braziliensis (Lvb) reached 83/1,000 inhabitants but declined sharply in the subsequent 2 years. Retrospective data shows that leishmaniasis is a sporadic endemic disease. Although the reasons for this epidemic are unclear some possible aetiological factors are discussed.

Adolescent↗
PubMedDate not supplied

Wild-type p53 gene transfection in human cultured sarcomas: effect of CDDP.

We examined the susceptibility of five human bone and soft tissue sarcoma cell lines to transfection with recombinant p53 adenovirus vector (AxCA-p53). Transfection efficiency was more than 90% at 72 h with AxCA-lacZ at a multiplicity of infection (MOI) of 50 in all the cell lines, except for MG-63 (p53 gene mutated) cells. Western blot analysis showed overexpression of both P21/Waf1 and Bax protein in all the cell lines, implying sufficient and successful p53 gene transfection. AxCA-p53 transfection at MOI of 50 resulted in a significant decline of viable cells at 72 h, due to apoptosis, in NY (mutated) and Saos-2 (deletion), but not in the other three lines. The two apoptosis-induced cell lines showed a gradual increase in Bax expression up to 72 h and non-detectable expression of Bcl-XL from 48 h, suggesting the involvement of an apoptosis-inducing mechanism. Pre-treatment with cis-diamminedichloroplatinum (II) (CDDP) at 0.1 microg/ml significantly suppressed tumor cell viability in NY and HuO-3N1 (mutated), but not in the other three lines including HT-1080 carrying the wild-type p53 gene, implying the existence of different mechanisms for the tumor suppressive effect of p53 gene transfection and CDDP. These results indicate that wild-type p53 gene transfection with CDDP is a promising therapy for some, but not all, non-resectable bone-and soft tissue sarcomas, regardless of intrinsic p53 gene status.

Adenoviruses, Human↗
PubMedDate not supplied

Expression of growth factors and their receptors in human early colorectal carcinomas: immunohistochemical study.

Human colorectal carcinomas have been demonstrated to express a variety of growth factors and their cognate receptors, forming multi-autocrine, juxtacrine and/or paracrine loops. Little information, however, is available on their expression in early colorectal carcinomas in which two genetic pathways exist, i.e. adenoma-carcinoma sequence and de novo carcinoma. This study was conducted in a total of 68 early colorectal carcinomas invading the submucosa, which were subdivided into two categories by the presence of adenomatous components, namely (a) 38 carcinomas with an adenomatous component and (b) 30 carcinoma without an adenomatous component. The tumous were also classified as polypoid, flat elevated and flat depressed type. Formalin-fixed, paraffinembedded specimens were immunostained for epidermal growth factor (EGF), transforming growth factor alpha(TGFalpha), cripto, EGF-receptor(EGFR) and c-ERBB2 gene product. Of the 68 early colorectal carcinomas, EGF, TGF-alpha, cripto, EGFR and c-ERBB2 products were detected at various degrees 24(35%), 50(74%), 31(46%), 11(16%), and 34(50%), respectively. The expression was compared between 35 polypoid carcinomas with an adenoma component (suitable for adenoma-carcinoma sequence), 14 flat carcinomas without an adenoma component (possible de novo carcinomas). A significantly higher incidence (P < 0.05) of expression of the following was noted; TGF-alpha in the polypoid carcinomas with an adenoma component, and EGF and c-ERBB2 gene product in the carcinomas without an adenoma component. There was no significant difference in the incidence of cripto and EGFR, implying common events between two categories. These results indicate that two pathways exist in tumourigenesis, in which the growth factors and their receptors are expressed in different manners. TGF-alpha might play a crucial role in carcinomas arising from adenoma, while EGF and c-ERBB2 gene products are strongly indicative of de novo carcinomas.

Adenoma↗
PubMedDate not supplied

Lack of rearranged Tpr-met mRNA expression in human gastric cancer cell lines and gastric mucosa and carcinoma.

The met protooncogene was activated by a rearrangement involving the fusion of tpr (1q25) and met (7q21-31) gene sequence in a human osteosarcoma cell line (HOS) incubated in vitro with N-methyl-N-nitro-N-nitrosoguanidine (MNNG). We examined the expression of tpr-met mRNA by means of the reverse transcription-nested polymerase chain reaction (RT-nested PCR) in human two gastric cell lines (MKN-1 and MKN-45), T-cell acute lymphocytic leukemia cell line (MOLT-4), and in gastric tissue samples including normal mucosa, intestinal metaplasia and carcinoma from three surgical specimens. A DNA fragment of 88-bp was amplified in MKN-1 and MOLT-4, 96-bp in MKN-45 and of 58-bp in all nine tissue samples including gastric carcinomas. The amplified DNA sequences were not homologous with the rearranged tpr-met gene. Our study indicated that rearranged tpr-met mRNA is not expressed either in human gastric carcinoma cell lines or in gastric mucosa and carcinoma.

Adenocarcinoma↗