Biomedical subjects

H Takagi

Publications and source records attributed to H Takagi.

At least 307 records · Page 17Linked to original sources

PubMed1998

Establishment of a concordant xenogeneic splenocyte injection model for the dynamic study of the marginal zone in the spleen.

BACKGROUND: This study was undertaken to establish a simple technique with which we could investigate the relationship between the marginal zone (MZ) in the spleen and antispecies antibody production, as well as to estimate the efficacy of various immunosuppressive treatments in xenotransplantation. METHODS: With a concordant xenogeneic combination (hamster-to-rat), the early phase reaction of the MZ was studied by use of quantitative histologic analysis, and complement-dependent cytotoxic antibody titers were determined in both a heart transplantation model and the splenocyte injection model. Furthermore, changes in the MZ were examined with isogeneic and allogeneic combinations with the splenocyte injection model. Next, the effect of cyclophosphamide, a promising immunosuppressant for concordant xenotransplantation, was examined by use of the splenocyte injection model. RESULTS: With a concordant xenogeneic combination, the MZ enlarged, and antihamster immunoglobulin M antibody synthesis increased after immunization in both models. On the other hand, with an isogeneic combination, the MZ did not expand, and with an allogeneic combination the MZ enlargement was not as great as that with a concordant xenogeneic combination. Cyclophosphamide suppressed the MZ expansion in a dose-dependent manner and effectively diminished antibody production in the splenocyte injection model. CONCLUSION: Dynamic studies of the MZ in the spleen with the splenocyte injection model are useful for the elucidation of the mechanisms of reaction and for estimating the efficacy of various immunosuppressive treatments in concordant xenotransplantation.

Animals↗

PubMed1998

[Xenotransplantation research for clinical practice].

In Japan a very strict brain death transplant bill has been effective since October 1997. However, the number of potential heart donors will be very few. In the United States and Europe, where most organ transplants are carried out, the chronic donor organ shortage has increased interest in the possible use of xenogeneic organs for transplantation in humans. Pigs, which are possible donors, now appear to be incompatible with humans and their organs will be hyperacutely rejected. The mechanism of hyperacute rejection is now well elucidated with clarification of the roles of complement and xenogeneic antigen. The strategies for overcoming hyperacute rejection involve creating transgenic pigs with insertion of human anti-complement genes and modification of their xenoantigens. The Japanese Society for Xenotransplantation has recently been established, ant the 5th International Congress for Xenotransplantation will be held in Nagoya in October 1999.

ABO Blood-Group System↗

PubMed1998

[Pulmonary emphysematous changes associated with Pneumocystis carinii pneumonia in an AIDS patient].

A 60-year-old man was admitted to our hospital complaining of non-productive cough. He had worked in Africa and received a blood transfusion after a traffic accident in 1985. On admission, the patient had remarkable hypoxemia and a decreased CD4+ lymphocyte count. A serological test for human immuno-deficiency virus (HIV)-1 was positive. His chest radiographs showed diffuse reticular and linear opacities, and broncoalveolar lavage findings established a diagnosis of Pneumocystis carinii pneumonia (PCP). A high-resolution CT of the chest revealed peripheral infiltrates and low attenuation areas (LAA) consistent with severe emphysematous alterations. We administered high-dose methylprednisolone and trimethoprim-sulphamethoxazole (TMP-SMX). Because of marked eosinophilia, TMP-SMX was discontinued, and the patient was given inhaled pentamidine isothiocyanate. Although there was a striking clinical improvement, the emphysema-like lesion on chest CT remained unaltered. LAA on CT had been modest in 1994, but had markedly enlarged during the three years thereafter, leading us to speculate that most of the LAA lesions recognized on admission might have developed in association with PCP. Pulmonary function tests showed an obstructive ventilatory defect and impaired diffusing capacity. Although PCP classically presents with diffuse ground-glass or fine granular opacities, thin-walled cavities or other atypical findings have recently been reported, especially in AIDS patients. There have been several reports about emphysema-like lesions associated with PCP. It was suggested that these lesions might be due to lung parenchyma destruction induced by HIV itself or increased elastase release from HIV-infected macrophages. This is the first report of PCP with pulmonary emphysematous lesions in Japan.

AIDS-Related Opportunistic Infections↗

PubMed1998

[A case of systemic lupus erythematosus developed with intestinal perforation].

A case of intestinal perforation associated with SLE is presented. A 54-year-old woman was diagnosed as having SLE twenty-five years ago when she had facial erythema, photosensitivity, oral aphtha, polyarthraliga, leukopenia, positive LE cell and positive antinuclear antibody. She had been treated with prednisolone and admitted to Kushiro City General Hospital because of one month history of fever and anorexia in February 1996. Laboratory findings did not reveal activity of SLE, and a diagnosis of urinary tract infection was made based on the findings of urinalysis. After severe diarrhea, disseminated intravascular coagulation (DIC) developed. A rectal perforation was revealed by endoscopic and radiological examination. An emergency laparotomy revealed necrosis of the rectum and sigmoidostomy was performed. The biopsied specimen of the rectum were diagnosed as gangrene of ischemic colitis histologically. Because of a penetration to the urinary bladder, an ureterocutaneostomy was performed. She died of sepsis and DIC on the 127th day of admission. Only 11 cases of intestinal perforation associated with SLE have been reported in Japan, and the association of vasculitis has been considered. In the present case, the prolonged use of prednisolone might cause the necrotizing ischemic colitis.

Female↗

PubMed1998

Identifying mRNAs involved potentially in corticopontine projection by modified differential display.

The basilar pons plays an important role in the establishment of the corticopontine projection by releasing a diffusible molecule which induces and directs collateral branchings along the corticospinal axon shafts. To reveal the molecule which is involved in the developing process of the corticopontine projection, we attempted to modify the mRNA differential display to search for genes expressed differentially in the basilar pons during the formation of the corticopontine projection by introducing the RGD motif (arginine-glycine-asparate) in the primers of the polymerase chain reaction. With our modification, we were able to identify 99 mRNAs expressed in the basilar pons but not in the cerebral cortex where the apparent pontine-derived activity is not observed. Among these 99 gene fragments, 3 novel fragments could be selected as final candidates of the pontine-derived molecule based on their expression patterns. Modified differential display is thus a promising method for identification of these genes.

Animals↗

PubMed1997

Cardiac angiosarcoma responding to multidisciplinary treatment.

Early detection of cardiac angiosarcoma is usually difficult and the prognosis is very poor. We experienced a 32-year-old man with cardiac angiosarcoma who responded to multidisciplinary treatment with recombinant interleukin-2, postoperative chemotherapy (cyclophosphamide, vincristine, doxorubicin, Dacarbazine) and radiation. At 30 months after surgery, there was no evidence of recurrence or metastasis in spite of incomplete resection.

Adult↗

PubMed1997

Molecular cloning and characterization of a novel TBP-1 interacting protein (TBPIP):enhancement of TBP-1 action on Tat by TBPIP.

The human immunodeficiency virus-1 (HIV-1) protein Tat, encoded by one of the HIV regulatory genes, tat, is reported to be essential for HIV gene expression and replication in infected cells. Observations suggest that several cellular factors cooperate with Tat in this process. Tat binding protein-1 (TBP-1) is reported to be one such cellular factor that specifically suppresses Tat-mediated transactivation of HIV replication in vitro. Here we have cloned a novel factor, TBP-1 interacting protein (TBPIP) from the mouse, which interacts with mouse TBP-1. TBPIP contains several kinase phosphorylation sites and co-localizes with TBP-1 in vivo. The fact that Tat activity is altered synergistically by the TBP-1 and an additional TBP-1 binding protein has not been reported before. We provide evidence that expression of TBPIP enhances the inhibitory action of TBP-1 on Tat-mediated transactivation in vitro. Our results suggest that TBPIP may have a key role in suppressing the Tat-mediated transactivation.

ATPases Associated with Diverse Cellular Activitie↗

PubMed1997

Characterization of Ret-Shc-Grb2 complex induced by GDNF, MEN 2A, and MEN 2B mutations.

We analyzed the intracellular signalling pathway through Ret activated by glial-cell-line-derived neurotrophic factor (GDNF), multiple endocrine neoplasia (MEN) 2A and 2B mutations. The results showed that all of them induce a signal transducing complex consisting of Ret, Shc, and Grb2 proteins. In addition, GDNF clearly activated a Ras-MAPK pathway in human neuroblastoma cells. Rat is expressed mainly as two isoforms that differ in the carboxy-terminal sequence: a long isoform (1114 amino acids) and a short isoform (1072 amino acids). The long isoform contains the consensus sequence for binding of the Shc PTB domain but not of its SH2 domain, whereas the short isoform has the consensus sequences for binding of both domains. In vitro binding assay revealed that the long isoform of the MEN2A-Ret protein and both isoforms of the MEN2B-Ret protein bound preferentially to the Shc PTB domain. On the other hand, the short isoform of MEN2A-Ret bound to the PTB and SH2 domains. In neuroblastoma cells expressing both isoforms of Ret, its activation by GDNF also resulted in the binding of both domains. GDNF and MEN 2A mutations activate Ret by inducing its dimerization, whereas the MEN 2B mutation increases Ret catalytic activity without dimerization. Our results thus suggest that Ret dimerization might be required for binding of the Shc SH2 domain to the short isoform.

3T3 Cells↗

PubMed1997

Facilitation of Ca2+ action potential frequency by a small G protein Rab3A in rat pituitary GH3 cells.

GH3 pituitary cells have high tendency to exhibit spontaneous Ca2+ action potentials and their frequency (Ca2+ APF) is increased by treatment with thyrotropin-releasing hormone (TRH). Although spontaneous Ca2+ firing was thought to be significant for the induction of oscillations in cytosolic Ca2+ concentration ([Ca2+]i), little attempt to elucidate the mechanism has been done so far. We demonstrate here that spontaneous Ca2+ APF in GH3 cells was increased 1.5-3 fold, comparable to that for TRH, by injection of guanosine 5'-0-3-thiotriphosphate (GTPgammaS), rab3A effector domain peptide, and phorbol-dibutyrate (PDBu), whereas guanosine 5'-O-(2-thiodiphosphate) (GDPbetaS), H-rab5 peptide, ras peptide, and 4 alpha-phorbol did not. The enhancement of Ca2+ firing by rab3A effector domain peptide was blocked by a protein kinase C (PKC) inhibitor, PKC(19-36). The present study suggests that the spontaneous Ca2+APF may be controlled by small G protein phosphorylated by PKC.

Action Potentials↗

PubMed1997

Altered mRNA expression of specific molecular species of fucosyl- and sialyl-transferases in human colorectal cancer tissues.

Human colorectal cancers express various cancer-associated carbohydrate determinants such as Lewis Y or sialyl Lewis A, suggesting a considerable alteration in glycosyltransferase activities occurring upon malignant transformation. We investigated the mRNA amounts of fucosyltransferase (Fuc-T) and sialyltransferase (ST) isoenzymes, including Fuc-T III, IV, V, VI and VII and ST-3N, ST-30 and ST-4, in human colorectal cancer tissues by Northern blotting and RT-PCR. Regarding fucosyltransferases, mRNA of Fuc-T III and VI was not significantly altered, and only Fuc-T IV mRNA showed a moderate increase in cancer tissues when compared with adjacent non-malignant colonic epithelia taken from the same patient (273 +/- 96%; p < 0.001). The moderate increase of Fuc-T IV message may be related to an enhanced expression of Lewis Y in colon cancer tissues. In the ST isoenzymes, mRNA for ST-3N remained unchanged, whereas that for ST-4 decreased significantly in cancer tissues, to 32 +/- 29%, (p < 0.005). The most remarkable finding was that the message of ST-30 was prominently increased in cancer tissues compared with non-malignant colorectal mucosa. When further investigated by quantitative RT-PCR assays on a larger series of patients with colorectal cancers, the average increase in mRNA for ST-30 was 459 +/- 200% compared with that in adjacent non-malignant epithelium (significant at p < 0.0001). The increase of ST-30 message was more prominent in the cancer tissues strongly expressing sialyl Lewis A than in the cancer tissues expressing sialyl Lewis A only weakly or moderately (significant at p < 0.05). The marked increase in the message of ST-30 is suggested to be related to an enhanced expression of sialylated carbohydrate determinants in colon cancer tissues including sialyl Lewis A, since the enzyme exhibited a significant activity against the type 1 chain carbohydrate substrate and produced the precursors for sialyl Lewis A synthesis, when its cDNA was expressed in Cos-7 cells.

Adenocarcinoma↗

PubMed1997

Purification and characterization of rabbit small intestinal cytochromes P450 belonging to CYP2J and CYP4A subfamilies.

A new form of P450 designated P450ib2 was purified from rabbit small intestine microsomes. This P450 had properties very similar, to P450ib (CYP2J1), and showed 88% identity with CYP2J1 in its first 20 NH2-terminal amino acid sequence, excluding 3 undetermined residues. Both P450ib and P450ib2 were immunohistochemically detected in the mucosal epitherial cells of the duodenum, jejunum, and ileum in the small intestine, whereas no immunoreactivity was observed in other tissues including liver, kidney, lung, colon, and stomach. The results support that the two closely related P450s are specifically localized in the rabbit small intestine. Another small intestinal P450, P450ia, was found to hydroxylate a wide variety of fatty acids including straight-chain, branched-chain, unsaturated, or hydroxy fatty acids, and prostaglandin A at the omega and (omega-1) positions. P450ia was identical with a rabbit kidney fatty acid omega-hydroxylase, CYP4A7, in its 25 NH2-terminal amino acid sequence, excluding 2 undetermined residues. The results identify P450ia as CYP4A7.

Amino Acid Sequence↗

PubMed1997

alpha-Galactosyl oligosaccharides conjugated with polyethylene glycol as potential inhibitors of hyperacute rejection upon xenotransplantation.

Antibodies to an alpha-galactosyl saccharide structure are mainly responsible for hyperacute rejection after pig-to-primate xenotransplantation. The beneficial effect of alpha-galactosyl oligosaccharides has been shown on the inhibition of anti-pig natural antibodies. We synthesized polyethylene glycol (PEG)-conjugates of alpha-galactosyl disaccharide (Di) and trisaccharide (Tri) as potential inhibitors of the rejection reaction. The half lives of Di, Tri, PEG-conjugated Di (Di-PEG) and PEG-conjugated Tri (Tri-PEG) were 18.1 +/- 2.3 min, 20.2 +/- 0.9 min, 38.7 +/- 2.8 min and 35.8 +/- 1.6 min, respectively. Furthermore, Di-PEG and Tri-PEG showed biphasic clearance, and their half lives at the second phase were longer than 10 hours. PEG-conjugated oligosaccharides (Di-PEG, Tri-PEG) markedly inhibited cytotoxic action of human sera to pig kidney cell line (PK15) compared to unconjugated oligosaccharides (Di, Tri). The binding of IgM antibodies to PK15 cells, however, was more strongly blocked by unconjugated oligosaccharides than PEG-conjugated oligosaccharides. This phenomenon can be explained by the finding that PEG has anti-complement activity and masks antigenic sites of oligosaccharides. In conclusion, conjugation of PEG to oligosaccharides provided two beneficial effects; prolonged intravascular retention time and anti-complement activity, upon systemic application of the oligosaccharides. The present findings opened a new approach to treatment of hyperacute rejection after xenotransplantation.

Animals↗

PubMed1997

Direct recognition of rat MHC antigens on rat antigen-presenting cells by mouse CD4+ and CD8+ T cells and establishment of T cell clones exhibiting a direct recognition pathway.

Alloantigens are recognized by T cells either through a direct pathway, which involves recognition of alloantigens expressed on allogeneic antigen-presenting cells (APC), or through an indirect pathway, which involves recognition of processed alloantigens presented by self APC. We investigated whether rat xenoantigens are also recognized by direct (xenogeneic APC-restricted) and/or indirect (self APC-restricted) pathways. C57BL/6 (B6) mouse anti-F344 or WKAH rat mixed lymphocyte reactions (MLRs) were partially inhibited by addition of either anti-mouse CD4 or CD8 monoclonal antibody (mAb) and almost completely blocked in the presence of both mAbs. These xenogeneic MLRs were almost completely inhibited by simultaneous depletion of both self and xeno APCs and only partially suppressed by the elimination of either type of APC, indicating that freshly prepared splenic mouse T cells can recognize rat xenoantigens through both direct and indirect pathways. Anti-F334 T cell lines were generated from B6 anti-F344 MLR cultures, and four CD4+ and four CD8+ T cell clones were isolated from these parental lines. The parental lines and those derived T cell clones were tested for their ability to proliferate depending on the presence of F344 APC. Proliferation of CD8 clones by stimulation with F344 APC was inhibited by the addition of anti-rat class I MHC mAb but not of anti-class II MHC mAbs. Conversely, proliferation of CD4 clones was reduced by addition of anti-class II MHC mAbs. Thus, these results indicate that xeno (rat)-reactive mouse T cells recognize xenoantigens via both indirect (self APC-restricted) and direct (xeno APC-restricted) pathways and that both CD4 and CD8 subsets of T cells participate in a direct pathway of xenoantigen recognition.

Animals↗

PubMed1997

Adhesion molecules and TGF-beta1 are involved in the peritoneal dissemination of NUGC-4 human gastric cancer cells.

Peritoneal dissemination frequently occurs after surgery in patients with gastric cancer. The presence of peritoneal metastasis after surgery affects prognosis. Very little is known about the biochemical processes involved in the initial attachment of gastric cancer cells to peritoneal mesothelial cells. We conducted in vitro and in vivo studies to assess the role of adhesion molecules and TGF-beta1 in this process, using 4 cell lines derived from human gastric cancers. NUGC-4 cells, which disseminate early after inoculation into the abdominal cavity of nude mice, predominantly express CD44H and beta1 integrin. We found that NUGC-4 cells adhered to monolayers of mesothelial cells more firmly than to other cell lines. Adhesion of NUGC-4 cells to mesothelial cells was partially inhibited by antibodies against CD44H or the beta1 subunit of integrin and was completely blocked by a combination of these 2 antibodies. Treatment with ligands for CD44H and beta1 integrin also inhibited adhesion. In the NUGC-4 cell culture medium, larger amounts of TGF-beta1 were detected in relation to the increase in cancer cells than in the other cell lines. TGF-beta1 increased the expression of CD44H in NUGC-4 cells and in mesothelial cells and augmented adhesion and implantation of NUGC-4 cells to mesothelial cells accompanied by accumulation of extracellular matrix (ECM) components. Treatment with antibodies against both CD44H and beta1 integrin inhibited the dissemination of NUGC-4 cells in the peritoneal cavity of nude mice and prolonged their survival time. Our findings suggest that CD44H and integrins mediate the initial attachment of gastric cancer cells to mesothelial cells and that TGF-beta1 participates in the promotion of the disease. Increased expression of CD44H and of the amount of ligands for CD44H and integrins induced by TGF-beta1 promotes early development of peritoneal dissemination.

Animals↗

PubMed1997

Effect of gene therapy with the herpes simplex virus-thymidine kinase gene on hepatic metastasis in murine colon cancer.

Hepatic metastasis of colon cancer is an important prognostic factor for survival. In this study, we examined the effect of gene therapy using the herpes simplex virus-thymidine kinase (HS-tk) gene with short-course ganciclovir (GCV) treatment for multiple hepatic metastases of murine colon cancer. Colon26 cells transfected with the HS-tk gene were found to be sensitive to GCV in a concentration-dependent way. On the other hand, induction of the HS-tk gene in the cells had no influence on cell growth in vitro. However, multiple hepatic metastases of Colon26 cells transfected with HS-tk gene were significantly suppressed by the GCV treatment. These results thus suggest that HS-tk gene therapy is useful for the treatment of hepatic metastasis in colon cancer.

Animals↗

PubMed1997

Secondary hyperparathyroidism: pathophysiology, histopathology, and medical and surgical management.

It is generally accepted that morphological changes of the parathyroid glands appear early in renal failure. When diffuse hyperplasia develops into a nodular type, the cells grow monoclonally and proliferate aggressively, with abnormal suppression of parathyroid hormone (PTH) secretion under high extracellular calcium. Based on histopathological and pathophysiological findings, patients with nodular hyperplasia in renal hyperparathyroidism might be refractory to medical treatment, including calcitriol pulse therapy. Thus, parathyroid surgery is indicated for individuals developing hypercalcemia, elevated PTH levels, and/or bone disease, who cannot be effectively treated medically. The detection of enlarged parathyroid glands by image diagnosis is another criterion for surgery. In our experience, parathyroidectomy is an effective treatment; however, the timing of the operation is important, because skeletal deformity and vessel calcification cannot be expected to diminish even after successful surgery. Technically, it is important to identify all parathyroid glands and, in autotransplantation, to use an adequate amount of suitable tissue, namely, a diffuse type of hyperplastic tissue, to guarantee satisfactory postoperative function.

Humans↗

PubMed1997

(1-->3)-beta-D-glucan determination in rat organs with limulus coagulation factor G.

One cause of a false positive limulus test after surgery or hemodialysis has been identified as extrinsic (1-->3)-beta-D-glucan which was derived from surgical gauze or cellulose dialyzer. However, there have been no investigations concerning intrinsic factors and the presence of (1-->3)-beta-D-glucan in mammalian organs. In this study, (1-->3)-beta-D-glucan in homogenate of various rat organs and stool was measured by a Gluspecy test (G test) using factor G, which specifically reacts with (1-->3)-beta-D-glucan. In small intestine and lung, large amounts of factor G-activating substance were observed and identified as (1-->3)-beta-D-glucan by a digestion study using end-(1-->3)-beta-D-glucanase. However, only very small amounts of (1-->3)-beta-D-glucan were found in the kidney, spleen, vena cava, aorta, thymus, heart and liver. In serum and plasma, no (1-->3)-beta-D-glucan was observed. On the other hand, extremely large amounts of (1-->3)-beta-D-glucan were found in stool. Minute amounts of (1-->3)-beta-D-glucan were observed in a variety organs except for the small intestine and lung. High levels of (1-->3)-beta-D-glucan found in the small intestine might be traced to contamination by stool in the small intestine, and such levels in the lung might derive from macrophages which have trapped (1-->3)-beta-D-glucan in the air.

Animals↗

PubMed1997

Steroid hormone-dependent overexpression of cytochromes P450 2A in liver tumors of TGF alpha transgenic male mice.

To clarify the mechanism underlying the male preference of liver tumor in transforming growth factor (TGF) alpha transgenic mice, we analyzed the sexually dimorphic expression of two P450s, i.e., female-specific mouse 15 alpha hydroxylase P450 (2A4) and coumarin 7-hydroxylase P450 (2A5). The expression of 2A4 mRNA in the livers of both transgenic and nontransgenic males was low compared with that in females. P450 2A5 mRNA in the transgenic males was slightly elevated in the adjacent non-tumorous tissues and dramatically elevated in the tumor compared with that in nontransgenic male liver. The activity of P450 2A5 was higher in females than in males in control and transgenic mice but the difference was smaller in the transgenic mice. The activity of P450 2A5 was exceptionally high in liver tumors of transgenic males, as indicated by mRNA expression. These results suggest that female-specific P450 2A5 is induced in the livers of TGF alpha transgenic male mice, particularly in liver tumors of transgenic male mice overexpressing TGF alpha, and may be useful as a marker for mouse hepatocarcinogenesis.

Animals↗