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Biomedical subjects

Y Yamaguchi

Publications and source records attributed to Y Yamaguchi.

At least 847 records · Page 47Linked to original sources
PubMed1990

Effects of etoposide (VP-16) on the survival and progression of cultured HeLa S3 cells through the cell cycle.

The survival of cultured HeLa S3 cells and their progression through the cell cycle after exposure to Etoposide (VP-16) were studied. The dose survival curve of exponentially growing cells was of a biphasic nature; the curve had an exponential slope starting from a small shoulder, and finally attained a plateau against increasing concentrations of the drug. Throughout the cell cycle, VP-16 exerted its main killing activity on cells in the late S and G2 phases, whereas cells in the G1 phase were resistant to the drug. By using a low concentration of VP-16, which allowed 85% of the treated cells to survive, it was found that the inhibition of the cell progression by the drug was greatest in the late S and G2 phases.

Cell Cycle↗
PubMed1990

Induction and regulation of cytochrome P450 K-5 (lauric acid hydroxylase) in rat renal microsomes by starvation.

The effects of starvation on rat renal cytochrome P-450s were studied. The content of spectrally measured cytochrome P-450 in the renal microsomes of male rats increased 2-fold with 72 h starvation, but cytochrome b5 and NADPH-cytochrome P-450 reductase were not induced. 7-Ethoxycoumarin O-dealkylation and aniline hydroxylation activities of the renal microsomes of control male rats were very low but were induced 2.5-3-fold by 72 h starvation. Aminopyrine N-demethylation and lauric acid hydroxylation activities were induced 1.5-2-fold by 72 h starvation. The changes in catalytic activities suggested that the contents of individual cytochrome P-450s in the renal microsomes were altered by starvation. The contents of some cytochrome P-450s were measured by Western blotting. P450 DM (P450IIE1), a typical form of cytochrome P-450 induced by starvation in rat liver, was barely detected in rat kidney and was induced 2-fold by 72 h starvation. P450 K-5, a typical renal cytochrome P-450 and lauric acid hydroxylase, accounted for 81% of the spectrally measured cytochrome P-450 in the renal microsomes of control male rats and was induced 2-fold by 72 h starvation. P450 K-5 was not induced in rat kidney by treatment with chemicals such as acetone or clofibrate. The renal microsomes of male rats contained 6-times as much P450 K-5 as those of female rats. These results suggest that P450 K-5 is regulated by an endocrine factor.

Animals↗
PubMed1990

Role of IL-5 in IL-2-induced eosinophilia. In vivo and in vitro expression of IL-5 mRNA by IL-2.

We recently demonstrated in vivo that IL-5 was an important mediator of eosinophilia in mice with parasite infections. In this study, we examined whether or not IL-5 was actually responsible for the eosinophilia induced by injection of human rIL-2. Mice administered hIL-2 developed eosinophilia during the course of the series of injections. This eosinophilia could be suppressed by a single injection of mAb against murine IL-5. The number of eosinophilic precursors increased more in the spleen cells of the IL-2-treated mice in comparison to the control mice, although in bone marrow precursors showed little change. Similarly, the number of granulocytic precursors increased markedly in the spleen cells of IL-2-treated mice. In vitro polymerase chain reaction amplification of cDNA subfragments corresponding to IL-5 mRNA (reverse transcription-polymerase chain reaction), followed by Southern blot analysis, revealed enhancement of IL-5 mRNA expression in spleen cells 3 days after starting the human IL-2 injections. We also observed enhanced murine IL-5 mRNA expression in spleen cells stimulated with IL-2 in vitro. The level of murine IL-5 mRNA expression by IL-2-stimulated spleen cells from normal mice increased at 24 h, reached a plateau after 48 h, and decreased again within 72 h of starting culture. These results indicate that the eosinophilia induced by IL-2 in vivo is presumably mediated by IL-5 released from IL-2-stimulated lymphocytes.

Animals↗
PubMed1990

Negative regulation of transforming growth factor-beta by the proteoglycan decorin.

Decorin is a small chondroitin-dermatan sulphate proteoglycan consisting of a core protein and a single glycosaminoglycan chain. Eighty per cent of the core protein consists of 10 repeats of a leucin-rich sequence of 24 amino acids. Similar repeats have been found in two other proteoglycans, biglycan and fibromodulin, and in several other proteins including Drosophila morphogenetic proteins. Expression of high levels of decorin in Chinese hamster ovary cells has a dramatic effect on their morphology and growth properties. We now report that this effect is due at least in part to the ability of decorin to bind transforming growth factor-beta, an autocrine factor that stimulates the growth of Chinese hamster ovary cells. As transforming growth factor-beta induces synthesis of decorin in many cell types, our results suggest that decorin may be a component of a feedback system regulating cell growth.

Animals↗
PubMed1990

Identification of the polyamine-induced protein as a periplasmic oligopeptide binding protein.

The physiological function of the polyamine-induced protein (PI protein), whose synthesis is stimulated at an early stage after the addition of putrescine to growing cells of a polyamine-requiring mutant of Escherichia coli (Mitsui, K., Igarashi, K., Kakegawa, T., and Hirose, S. (1984) Biochemistry 23, 2679-2683), has been studied. The following findings clearly show that the PI protein is a binding protein of an oligopeptide transport system. (a) PI protein was found in a periplasmic fraction. (b) When the restriction map of a clone for the PI protein gene was compared with Kohara's physical map (Kohara, Y., Akiyama, K., and Isono, K. (1987) Cell 50, 495-508), the gene was found at 27 min of the E. coli chromosome, where genes for an oligopeptide transport system were located. (c) The clone contained a 1,629-nucleotide open reading frame encoding a 543-amino acid protein whose calculated Mr was 60,901, and the predicted amino acid sequence from this open reading frame was quite similar to that of an oligopeptide binding protein of Salmonella typhimurium. (d) When the transport activity of a tripeptide, Gly-Leu-125I-Tyr, was measured in a polyamine-requiring mutant of E. coli growing both in the presence and absence of putrescine, the activity was higher in the cells growing in its presence. (e) Polyamine stimulation of cell growth was greater when an oligopeptide rather than corresponding amino acids was added to the medium. These results suggest that the polyamine stimulation of PI protein synthesis at the early stage after the addition of putrescine contributes to the polyamine stimulation of cell growth through the supply of nutrients.

Amino Acid Sequence↗
PubMed1990

IL1 induces proliferation and IL6 mRNA expression in a human astrocytoma cell line: positive and negative modulation by chorela toxin and cAMP.

A human astrocytoma cell line, U373, and its subclones showed a high proliferative response to IL1 alpha or IL1 beta with concomitant IL6 production and IL6 mRNA accumulation. IL1 itself raised neither the cAMP level nor the intracellular Ca2+ level nor did it induce phosphatidylinositol (PI) breakdown. Chorela toxin (CT) and pertussis toxin (PT)-pretreatment markedly inhibited IL1-induced proliferation, while CT enhanced IL1-induced IL6 mRNA expression significantly. Drugs raising cellular cAMP level or cAMP analogues augmented IL1-mediated IL6 mRNA expression but much less. Although cAMP is not directly involved in the IL1 action, cAMP thus has a modulatory effect on IL1-mediated IL6 gene activation.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1990

Analysis of glycosaminoglycan substitution in decorin by site-directed mutagenesis.

Posttranslational glycosaminoglycan attachment to decorin, a chondroitin/dermatan sulfate proteoglycan, was studied by expression of a wild-type decorin cDNA and several mutagenized forms in two types of mammalian cells. Transfection of the wild-type cDNA resulted in the synthesis of an authentic chondroitin/dermatan sulfate proteoglycan similar to the decorin molecule synthesized by cultured human fibroblasts. Conversion of the serine residue that serves as the attachment site for the sole glycosaminoglycan chain in decorin to a threonine residue greatly reduced the efficiency of the glycosaminoglycan substitution. Less than 10% of the threonine-mutated core protein acquired a glycosaminoglycan chain, whereas most of the core protein was secreted without such substitution. Expression of cDNA in which an alanine residue had been introduced into the substituted serine position resulted in the secretion of core protein with no detectable glycosaminoglycan. Conversion to alanine of either one of the glycine residues that are adjacent to the substituted serine yielded the proteoglycan form of decorin. These results show that the xylosyltransferase responsible for the initiation of the glycosaminoglycan chain on the core protein can use a threonine residue for this substitution instead of a serine residue, but that such substitution is only partial, creating a "part-time" proteoglycan. Moreover, variations are possible in the sequence context of a glycosaminoglycan-substituted serine residue without loss of glycosaminoglycan substitution. The conformation of the substitution site may therefore be important for xylosyltransferase recognition.

Animals↗
PubMed1990

Effects of hyperglycaemia on sorbitol and myo-inositol contents of cultured embryos: treatment with aldose reductase inhibitor and myo-inositol supplementation.

To demonstrate the myo-inositol depletion hypothesis in hyperglycaemia-induced embryopathy, rat conceptuses of 9.5 days of gestation in the early head-fold stage were grown in vitro during neural tube formation for 48 h with increasing amounts of glucose. The effects of an aldose reductase inhibitor and the myo-inositol supplementation were also investigated. Sorbitol and myo-inositol contents were measured in separated embryos and extra-embryonic membranes including yolk sac and amnion at the end of culture. After addition of 33.3 mmol/l and 66.7 mmol/l glucose to the culture media, the myo-inositol content of the embryos was significantly decreased by 43.1% (p less than 0.05) and 64.6% (p less than 0.01) of the control group, while a marked accumulation of sorbitol was observed (25 and 41 times that of the control). Although the addition of an aldose reductase inhibitor (0.7 mmol/l) to the hyperglycaemic culture media containing an additional 66.7 mmol/l glucose significantly reduced the sorbitol content of embryos to approximately one-eighth, the myo-inositol content of embryos remained decreased and the frequency of neural lesions was unchanged (23.1% vs 23.9%, NS). Supplementation of the myo-inositol (0.28 mmol/l) completely restored the myo-inositol content of the embryos and resulted in a significant decrease in the frequency of neural lesions (7.1% vs 23.9%, p less than 0.01) and a significant increase in crown-rump length and somite numbers. Much less significantly, sorbitol accumulation was also observed in the extra-embryonic membrane in response to hyperglycaemia, neither hyperglycaemia nor the myo-inositol supplementation modified the myo-inositol contents of the extra-embryonic membrane.(ABSTRACT TRUNCATED AT 250 WORDS)

Aldehyde Reductase↗
PubMed1990

An electron microscopic study of glomerular lesions in hereditary nephrotic mice (ICGN strain).

Glomerular lesions in hereditary nephrotic mice (ICGN strain) were investigated by electron microscopy. The glomeruli of unaffected animals, which appeared normal by light microscopy, had developed an ultrastructural change in the glomerular capillary basement membrane (GCBM). There was a partial thickening of the GCBM with bilaminar splitting of the lamina densa and an electron-dense fibrillar material exhibiting cross-striations. In affected animals, light microscopy revealed a marked thickening of GCBM and an increase of mesangial matrix without cellular proliferation. By electron microscopy, multilaminar splitting of the lamina densa in the thickened GCBMs and fusion of the epithelial foot processes were observed. In some severely affected animals, immune complex deposition was found in GCBM, but little if any was observed in other animals. In the end, the glomeruli were globally sclerosed. Our findings suggest that initial structural abnormalities in GCBM may play an important role in the onset and development of the disease, though subsequent events such as immune complex deposition would modify the disease.

Animals↗
PubMed1990

The analysis of lymphocyte surface receptors recognized by wheat germ agglutinin for negative regulation of immune responses in cancer patients.

The population of peripheral blood lymphocytes expressing surface receptors for a lectin, wheat germ agglutinin (WGA), which has been shown to recognize the same receptors as the soluble immune suppressor factor (SISF) elaborated from suppressor cells on the lymphocyte surface, was analyzed by using fluorescein isothiocyanate-conjugated WGA on flow cytometry in cancer patients. It was found that the populations of WGA+ lymphocytes in cancer patients were significantly higher than those in either normal volunteers or patients with benign disease and increased with progress of the tumor. The populations decreased after treatment in patients who underwent curative resection of the tumor and in responders of immunochemotherapy but not in those who received non-curative surgery or in non-responders. It was suggested that the increase of receptors for SISF on the lymphocyte surface might play an important role in the negative regulation of immune responses in cancer patients and that WGA might be a useful parameter for immunosuppression.

Antigens, Surface↗
PubMed1990

Morphological rejection phases and cytotoxic activity in peripheral blood lymphocytes in canine lung allo-transplantation.

The relationship between the morphological changes in allografted lungs and the cytotoxicity of recipient peripheral blood lymphocytes was studied. Left lung allotransplantations were performed in 14 adult mongrel dogs. Four dogs were treated with cyclosporin A (20 mg/kg/day po.) and four were treated with FK-506 (0.1 mg/kg/day im.) for 10 days. Six dogs were not given any immunosuppressive drugs. Cytotoxicity was measured with the 51Cr release assay in which the donor skin fibroblasts were used as target cells. The histological changes of the grafted lungs were classified into three grades: grade 0; no abnormal findings, grade I; perivascular and peribronchial mononuclear cell infiltration, and grade II; edema, hemorrhage and a fibrin-like substance in the alveolar space in addition to the findings of grade I. The grafted lungs of the dogs with elevated cytotoxicity showed the histological findings of grade II (8 of the 14 dogs) and significantly higher cytotoxicity (44.1 +/- 25.7 per cent) were seen in these dogs than in those with grade 0 (2.0 +/- 3.9 per cent) or grade I (2.6 +/- 1.9 per cent). It is therefore considered that the cytotoxicity against donor skin fibroblasts in recipient peripheral blood lymphocytes is associated with morphological rejection phases in allografted lungs.

Animals↗
PubMed1990

Nd:YAG laser irradiation to intraluminal mass lesions of the superior vena cava under laser balloon angioscopy in an experimental canine model.

A laser balloon angioscopic procedure was developed in a canine model for intraluminal mass lesions in the superior vena cava, using an endoscope bearing a very thin balloon through which Nd:YAG laser could penetrate. The balloon was made from artificially modified natural latex rubber and well expanded with saline infused through a biopsy channel. The endoscopic image of the object obtained through direct contact of the balloon expanded with saline was clear enough to observe the internal surface or branches in not only normal, but also pathological conditions of the canine SVC. The Nd:YAG laser was able to be successfully irradiated through the balloon using this procedure which, although still in its preliminary stage, may be a useful clinical, diagnostic and therapeutic tool of the future.

Angioplasty, Balloon↗
PubMed1990

Endoscopic Nd:YAG laser surgery on malignant and benign lesions of the trachea and carina.

A total of 47 patients with malignant and benign lesions in the trachea and carina were used to demonstrate the effectiveness of endoscopic Nd:YAG laser surgery. The histology consisted of 37 malignant and 10 benign lesions, and 23 of the patients had severe symptoms with laser surgery being performed as a lifesaving emergency. Endoscopic Nd:YAG laser treatment was able to dilate the tracheal calibers from 2.6 +/- 0.9 mm to 6.1 +/- 1.4 mm in the emergency cases with a remarkable effect and brought relief from wheezing and dyspnea, with an objective improvement of more than 25 per cent in peak expiratory flow rate being demonstrated. Furthermore, the tracheal diameters were able to be dilated from about 7 mm to 10 mm in the non-emergency cases. A remarkable effect was achieved in patients with intraluminal or mixed types of tumors among both the emergency and non-emergency cases. The survival rates of the emergency patients in whom a remarkable effect was achieved were definitely better than those in whom only fair or poor effects were achieved and, in the non-emergency cases, similar results were demonstrated. In conclusion, the application of endoscopic Nd:YAG laser surgery to tracheal stenotic diseases has an instantaneous and definite effect on luminal dilatation and shows significance as a lifesaving procedure. Moreover, the resultant improvement in the patients' general condition could make it possible for them to undergo other combined therapy and prolong their life span. Endoscopic Nd:YAG laser surgery is thus considered to be a very effective and established procedure for the treatment of tracheal stenotic lesions.

Bronchoscopy↗
PubMed1990

Structural comparison of murine T-cell (B151K12)-derived T-cell-replacing factor (IL-5) with rIL-5: dimer formation is essential for the expression of biological activity.

T-cell-replacing factor (TRF)/IL-5 is a T-cell-derived glycoprotein which has pleiotropic activity on lymphoid and myeloid cells. IL-5 polypeptide translated into Xenopus oocytes are heterogeneous in molecular size (40,000 to 60,000 under nonreducing conditions) and yields a monomeric form (Mr of 25,000 to 30,000) under reducing conditions (J. Immun., 140, 1175-1181, 1988). We purified T-cell-derived TRF and rIL-5 using anti-TRF/IL-5 antibody-coupled affinity column from supernatants of a T-cell hybridoma B151K12 and supernatants of HeLa cells, respectively, which had been transfected with murine IL-5 cDNA, and determined their partial N-terminal amino acid sequence (27 residues for B151-TRF and 13 residues for rIL-5). A single amino acid sequence of each sample obtained beginning from methionine that was identical to that predicted from IL-5 cDNA. This finding supports the notion that secreted B151-TRF polypeptide consists of 113 amino acids. Purified B151-TRF supported eosinophilopoiesis of human bone marrow cells as effective as mouse rIL-5 and human rIL-5. B151-TRF competitively inhibited 35S-labeled rIL-5 binding to target cells to the same extent at rIL-5. Treatment of purified rIL-5 and B151-TRF with reducing reagents such as 2-ME, sodium borohydride or dithiothreitol produced a monomeric form of IL-5 which did not exert a biological activity. Reduction and alkylation of rIL-5 caused the loss of binding to its target cells. These results strongly suggest that B151-TRF exists as a homodimer and its primary structure and secondary structures are identical to those of rIL-5. Moreover, the formation of inter-molecular disulfide bond(s) linked by two pairs of cystein residues is essential for the expression of the biological activity of mouse IL-5.

Amino Acid Sequence↗
PubMed1990

Irradiation for xenogeneic transplantation.

Xenogeneic transplantation (XT) is the transplantation of organs or tissues from a member of one species to a member of another. Mammalian species frequently have circulating antibody which is directed against the foreign organ irrespective of known prior antigen exposure. This antibody may lead to hyperacute rejection. There is no reliable means to avert hyperacute rejection once it ensues so efforts must be directed towards eliminating the pre-existing antibody. In those species in which hyperacute rejection of xenografts does not occur, cell-mediated rejection, similar to allograft rejection, may occur. It is in the prevention of this latter form of rejection that radiation is most likely to be beneficial in XT. Both total lymphoid irradiation (TLI) and selective lymphoid irradiation (SLI) have been investigated for use in conjunction with XT. TLI has contributed to the prolongation of pancreatic islet-cell xenografts from hamsters to rats. TLI has also markedly prolonged the survival of cardiac transplants from hamsters to rats. A more modest prolongation of graft survival has been seen with the use of TLI in rabbit-to-rat exchanges. Therapy with TLI, cyclosporine, and splenectomy has markedly prolonged the survival of liver transplants from hamsters to rats, and preliminary data suggest that TLI may contribute to the prolongation of graft survival in the transplantation of hearts from monkeys to baboons. SLI appears to have prolonged graft survival, when used in conjunction with anti-lymphocyte globulin, in hamster-to-rat cardiac graft exchanges. The current state of knowledge of the use of irradiation in experimental XT is reviewed.

Animals↗
PubMed1990

Comparison of islet cell antibodies, islet cell surface antibodies and anti-bovine serum albumin antibodies in type 1 diabetes.

The present study was undertaken to compare the changes in islet cell antibodies (ICA), islet cell surface antibodies using rat insulinoma cells (RINr-ICSA), and anti-bovine serum albumin antibodies (BSA-Ab) in the clinical course of type 1 (insulin-dependent) diabetes. Sera were obtained from 57 patients with type 1 diabetes and 47 normal controls. ICA, RINr-ICSA and BSA-Ab were detected by an enzymatic immunohistochemical method, an indirect immunofluorescence method and an enzyme-linked immunosorbent assay, respectively. The incidence of ICA significantly decreased with the duration of diabetes: less than 1 year: 5/6 (83%); 1-2 years: 3/6 (50%); 2-3 years; 2/6 (33%); greater than 3 years 6/39 (15%). There was a significant positive correlation between RINr-ICSA and BSA-Ab (P less than 0.05). These findings suggest that RINr-ICSA or BSA-Ab may be produced by some similar immune mechanism which is, however, different from ICA, and that they have no direct relation to the clinical course of diabetes.

Adolescent↗