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Biomedical subjects

A Yamaguchi

Publications and source records attributed to A Yamaguchi.

At least 487 records · Page 27Linked to original sources
PubMed1992

[Comparative study of anticoagulant management after coronary artery bypass surgery--warfarin versus dipyridamole].

A prospective randomized study was performed in 137 coronary artery bypass surgery cases to determine if the administration of antiplatelet drugs would improve the patency of coronary artery bypass grafts. The warfarin group received warfarin and thrombotest was controlled to 20% or so. The dipyridamole group received both 300 mg of dipyridamole and 250 mg of aspirin orally each day. These two groups were compared for study in grafts patency. Results were analyzed by chi-square. In the warfarin group, 66 patients had three ITA-LAD grafts and 115 saphenous vein grafts (including 4 sequential grafts). In the dipyridamole group, 71 patients underwent 38 ITA grafts and 167 saphenous vein grafts (including 56 sequential grafts). Eighty-eight of the 107 grafts (82%) were patent in the warfarin group, and 190 of 205 grafts (95%) were patent in the dipyridamole group (p less than 0.01). Of the two ITA grafts in the warfarin group, no graft was occluded, a patency of 100%. In the dipyridamole group, 35 of 38 ITA grafts (92%) were patent. In the warfarin group, 86 of 105 saphenous vein grafts (82%) were patent. In the dipyridamole group, 155 of 167 saphenous vein grafts (95%) were patent (p less than 0.01). In the study of grafted coronary vessel, the patency of left anterior descending coronary artery, diagonal branch and right coronary artery was not significant between two groups. In the dipyridamole group, the patency of left circumflex coronary artery was 93%, and that of the warfarin group was 50% (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

[Surgical treatment of Candida endocarditis involving mitral valve--a case report].

A 53-year-old male with a low pulmonary function (FEV1.0 500 ml) and cachexia was admitted for a remittent fever. Blood culture along with echocardiography indicating vegetation on the anterior mitral leaflet confirmed Candida endocarditis involving mitral valve. Following anti-fungal drug therapy, mitral valve replacement was performed. Surgical specimen of mitral valve showed vegetation on the anterior mitral leaflet with Candida albicans. The post-operative course was uneventful, through the anti-fungal drug therapy was compelled to be discontinued owing to drug allergy. He was discharged on the 67th postoperative day. There was no evidence of recurrence without medication for 9 months after his discharge.

Candidiasis↗
PubMed1991

DNA deletion and its parental origin in Angelman syndrome patients.

DNA deletion studies using 5 DNA markers localized at 15q11-q12 were performed in 14 Angelman syndrome (AS) patients (9 sporadic and 5 familial cases). A one-copy density for one or more of the 5 loci was detected in 8 (57.1%) of the 14 patients. A deletion of only the D15S11 locus was detected in one sporadic patient, that involving only the D15S10 in 3 familial patients (sibs in a family), that spanning 3 loci (D15S11, D15S10, D15S12) in one sporadic patient, and that spanning 4 loci (D15S9, D15S11, D15S10, D15S12) in the other 3 sporadic patients. The deletion common to our patients as well as to the reported patients may be confined to a segment between D15S11 and D15S10, if the 5 loci are ordered as cen-D15S18-(D15S9-D15S11-D15S10)-D15S12-qt er. This site overlaps but is more distal to the common deletion site in Prader-Willi syndrome (PWS) patients. In the family of the 3 sibs, both of the phenotypically normal mother and maternal grandfather also have deletions of the D15S10 locus. These results were consistent with the genomic imprinting hypothesis for the occurrence of AS, i.e., the lack of a maternally derived locus leads to AS, but may not support a model that AS is the alternative phenotype of PWS at the identical locus.

Abnormalities, Multiple↗
PubMed1991

Expression of c-erbB-2 oncoprotein in gastric carcinoma. Immunoreactivity for c-erbB-2 protein is an independent indicator of poor short-term prognosis in patients with gastric carcinoma.

Correlations of c-erbB-2 protein expression with clinical outcomes of gastric carcinomas were studied in 189 gastric carcinomas. There were 23 (12.2%) carcinomas with evidence of c-erbB-2 protein in which the reaction was localized to the cell membrane. There was no significant association between c-erbB-2 staining and the macroscopic or histologic type of the carcinomas. c-erbB-2-stained tumors were more likely to be associated with serosal invasion, nodal involvement, and peritoneal metastasis, than c-erbB-2-unstained ones. In addition, c-erbB-2 was stained in none of early gastric carcinomas. The 5-year survival rates of the c-erbB-2 protein-positive and the protein-negative group were 11% and 50%, respectively. When the c-erbB-2 tissue status and seven clinicopathologic variables as conventional prognostic factors were entered simultaneously into the Cox regression model, serosal invasion, hepatic metastasis, peritoneal metastasis, nodal status, and c-erbB-2 tissue status emerged as independent prognostic variables. The results suggested that c-erbB-2 protein expression might be enhanced in advanced stages during the progression of gastric carcinoma. In this particular group of patients, immunoreactivity for c-erbB-2 protein is an indicator of poor short-term prognosis.

Adult↗
PubMed1991

The expression of proliferative-associated nuclear antigen p105 in gastric carcinoma.

The expression of proliferation-associated nuclear antigen p105 of gastric carcinomas was studied by multiparameter flow cytometric and immunohistochemical technique. Multiparameter flow cytometric analysis revealed that p105 expression was rarely observed in the resting cells of normal gastric epithelium. On the contrary, the immunofluorescence (IF) intensity of cancer cells in G1 phase was approximately two-fold to three-fold greater than that of G0 phase of cancer cells or normal gastric epithelium. The p105 antigen content of cancer cells increased with cell cycle progression, and increased more rapidly in cells in late S-phase than in cells in G0 and early S-phase. Microphotometric study demonstrated that cells in M-phase exhibited a dramatic increase in the amount of the antigen, and the IF intensity of the mitotic cells were approximately five-fold to ten-fold greater than that of cells in G1 and S-phase. These results indicate that the antigen demonstrated by the p105 monoclonal antibody is present in the G1, S, G2, M-phases, but not in the G0 phase. Immunohistochemical technique demonstrated that patients with lymph node metastases are more likely to have high p105-positive rates than did node-negative patients. The mean p105-positive rates of aneuploid tumors was significantly higher than those of diploid tumors. From these results the authors speculate that the measurement of p105-positive rates may be a powerful prognostic indicator of gastric carcinoma.

Antigens, Neoplasm↗
PubMed1991

Stoichiometry of metal-tetracycline/H+ antiport mediated by transposon Tn10-encoded tetracycline resistance protein in Escherichia coli.

The tetracycline resistance protein (TetA) endoded by transposon Tn10 mediates the efflux of divalent cation-tetracycline chelating complexes [Yamaguchi, A., Udagawa, T. and Sawai, T. (1990) J. Biol. Chem. 265, 4809-4813]. It was confirmed that protons were antiported with the complexes through an electrically-neutral process because the antiport consumed delta pH but not delta psi. The quantitative relationship between delta pH and delta pTC determined by a flow-dialysis method clearly indicated a 1:1 stoichiometry of the monocationic metal-tetracycline/H+ exchange.

Cell-Free System↗
PubMed1991

Metal-tetracycline/H+ antiporter of Escherichia coli encoded by a transposon Tn10. Histidine 257 plays an essential role in H+ translocation.

The transposon Tn10-encoded tetA gene product is a metal-tetracycline/proton antiporter (Yamaguchi, A., Udagawa, T., and Sawai, T. (1990) J. Biol. Chem. 265, 4809-4813). Its tetracycline transport activity was inhibited by a histidine-specific reagent, diethyl pyrocarbonate. Among five histidine residues in this antiporter, only His257 is located in the putative transmembrane helices. Thus, His257 was replaced by Glu or Asp. Inverted vesicles containing the Glu257 and Asp257 mutant proteins showed only 20 and 10% of the tetracycline uptake of wild-type vesicles, respectively. In contrast to wild-type vesicles, the mutant vesicles showed no tetracycline-dependent proton translocation, indicating that the mutant proteins had lost the tetracycline/H+ antiport activity. The significant 60Co2+ uptake without proton translocation by the mutant vesicles also confirmed that the mutant carriers act as uniporters of a metal-tetracycline complex. The metal-tetracycline uniport by the mutant proteins was not inhibited by diethyl pyrocarbonate, indicating that His257 is the only histidine residue essential for proton translocation. These mutant proteins conferred about half-level resistance to tetracycline, probably due to their catalyzing downhill efflux of a metal-tetracycline complex out of the cells.

Amino Acid Sequence↗
PubMed1991

Evaluation of immunoreactivity for erbB-2 protein as a marker of poor short term prognosis in gastric cancer.

Using a polyclonal antibody that is monospecific for the erbB-2 oncogene product, an immunohistochemical study of the expression of erbB-2 protein was performed in formalin-fixed paraffin-embedded tissue sections from 260 primary gastric cancers. erbB-2 protein expression in which the reaction was localized to the cell membranes was observed in 31 (11.9%) cancers. All nontumor cells and normal gastric epithelium were negative for membrane staining. There was not a significant association between erbB-2 staining and histological type or venous invasion. erbB-2 protein expression was associated with serosal invasion, lymph node metastasis, and lymphatic invasion. In addition, erbB-2 protein expression correlated with a high number of lymph node metastases. Furthermore, the risk of recurrence in lymph node was over 3 times higher in patients with erbB-2 protein-positive tumors than in those with erbB-2 protein-negative ones. When erbB-2 protein expression and the clinical parameters were entered simultaneously into the Cox regression model, erbB-2 protein expression emerged as an independent prognostic indicator. Patients with erbB-2 protein-positive tumors had 5-fold greater relative risk of death, as compared with those with erbB-2 protein-negative tumors. These results indicate that erbB-2 protein expression is an important independent prognostic indicator in gastric cancer. The high malignant potential of erbB-2 protein-positive tumors may be associated with the very high potential for lymph node metastasis.

Biomarkers, Tumor↗
PubMed1991

Role of prostaglandins in interleukin-1-induced bone resorption in mice in vitro.

The mechanism of bone resorption induced by interleukin 1 (IL-1) was examined in mice using three different in vitro assay systems: a fetal long bone organ culture system, a bone marrow culture system, and a coculture system of primary osteoblastic cell populations and spleen cells. In the organ culture system, recombinant human IL-1 alpha (rhIL-1 alpha) increased both bone resorption and osteoclast number. Both were partially suppressed in the presence of indomethacin. In the marrow culture, both rhIL-1 alpha and rhIL-1 beta stimulated osteoclastlike cell formation, which was completely inhibited by adding indomethacin concurrently. Furthermore, there was a good correlation between the number of osteoclastlike cells formed and the amount of prostaglandin E2 (PGE2) released into the culture media. This indicates that PGE2 is involved in the mechanism of IL-1-mediated osteoclastlike cell formation. In the coculture of primary osteoblastic cell populations and spleen cells, rhIL-1 again stimulated osteoclastlike cell formation, which was inhibited by adding indomethacin. In the cocultures in which direct interaction between osteoblastic cells and spleen cells was inhibited, PGE2 synthesis was similarly increased but no osteoclastlike cells were formed. These results indicate that IL-1 induces osteoclast formation by a mechanism involving PG (most likely PGE2). Furthermore, direct interaction between osteoclast progenitors and osteoblastic cells is required in the osteoclast recruitment induced by IL-1.

Acid Phosphatase↗
PubMed1991

cDNA and deduced amino acid sequence of mouse matrix gla protein: one of five glutamic acid residues potentially modified to gla is not conserved in the mouse sequence.

A cDNA library was constructed using the mouse osteoblastic cell line MC3T3-E1 treated with 1 alpha,25-dihydroxyvitamin D3, based on the finding that the treatment increased ninefold the expression of 0.7 kb matrix gla protein (MGP) mRNA. cDNA clones encoding mouse MGP were isolated from the library. The nucleotide sequence showed an open reading frame of 312 nucleotides encoding 104 amino acids. Murine MGP shared 84-89% amino acid sequence homology with bovine, rat, and human MGP. However, there are five glutamic acid residues potentially modified to gamma-carboxyglutamic acid (gla) in those species; in murine MGP, lysine replaced glutamic acid 37. Also, an extra tyrosine was added at the carboxyl terminus. The significance of the substitution is discussed in relation to the gamma-carboxylation sites in MGP protein.

Amino Acid Sequence↗
PubMed1991

Clinical significance of tumor marker NCC-ST 439 in large bowel cancers.

We examined serum NCC-ST 439 for its significance as a tumor marker of large bowel cancer in 121 patients with primary and 36 with recurrent large bowel cancer. Serum NCC-ST 439 was positive in 27.3 percent of the former and 66.7 percent of the latter. It was false-positive in only 5.6 percent of patients with benign diseases. Positive serum NCC-ST 439 correlated with lymph node and liver metastases. The combination assay for NCC-ST 439, CEA, and CA19-9 was positive in 49.6 percent of the patients with primary tumors and 88.9 percent of those with recurrent tumors; in other words, the diagnostic accuracy improved. The results demonstrated that the determination of serum NCC-ST 439 in large bowel cancer might be useful in cancer staging and that NCC-ST 439, if used in combination with CEA, is particularly useful in diagnosing recurrences because of its improved diagnostic accuracy.

Antibodies, Monoclonal↗
PubMed1991

Investigation of colonic prostaglandins in carcinogenesis in the rat colon.

Large bowel carcinoma was induced in rats by injecting MNNG intrarectally, and changes in the large bowel mucosa prostaglandin (PG) with time were determined. The PGE2 levels of the colonic mucosa in a control group were 20.9 +/- 9.7 (pg/mg total protein) at 5 weeks, 25.5 +/- 9.7 at 10 weeks, 26.5 +/- 18.1 at 20 weeks, and 34.8 +/- 12.7 at 40 weeks. The PGE2 levels in the MNNG-treated group were 44.7 +/- 6.2 at 5 weeks, 43.1 +/- 14.9 at 10 weeks, 70.1 +/- 23.4 at 20 weeks, and 79.7 +/- 54.1 at 40 weeks. The intrinsic PGE2 levels of the noncancerous mucosa were thus significantly higher for the MNNG group than for the control group at all weeks. At 40 weeks, the PGE2 levels of cancer lesions were significantly high compared with those of the noncancerous area. In the cancerous lesions, 6-keto-PGF1 alpha and PGF2 alpha decreased and TXB2 increased significantly at 40 weeks. The observations demonstrated that PGE2 was implicated as a promoter in the development and proliferation of carcinoma in MNNG-induced large bowel carcinogenesis in rats.

Animals↗
PubMed1991

Detection by CT during arterial portography of colorectal cancer metastases to liver.

A prospective evaluation of the accuracy of real-time ultrasonography (US), computed tomography (CT), infusion hepatic angiography (IHA), and computed tomography during arterial portography (CT-AP) was performed on 65 resected liver metastases of colorectal cancers. The total detection rate was 58.5 percent for US, 56.3 percent for CT, 55.4 percent for IHA, and 86.2 percent for CT-AP. The sensitivity of 29 lesions with diameters of smaller than 1 cm was 65.5 percent for CT-AP, CT found only two, and both US and IHA localized no more than three. The smallest lesions detectable by CT-AP were as small as 0.4 cm in diameter. CT-AP proved most useful in detecting the liver metastases, and the use of this technique is recommended for preoperative planning of hepatectomy on patients with liver metastases.

Angiography↗
PubMed1991

Clonal osteogenic cell lines express myogenic and adipocytic developmental potential.

Clonal osteoblastic cell lines were isolated from neonatal rat calvariae and characterized with regard to a number of features associated with authentic osteoblasts. These included elevated alkaline phosphatase activity (relative to fibroblasts), PTH and PGE2-stimulated increases in cAMP, the predominant synthesis of type 1 collagen, and the production of a mineralized matrix in vitro. By these criteria, five clones with osteoblast-like phenotypes were identified (ROB-C8a, C11, C20, C23, and C26) which varied somewhat in shape, levels of alkaline phosphatase activity, and in responsiveness to PTH and PGE2. C11, C20, and C23 responded to both effector substances, whereas C8a only responded to PTH and C26 only responded strongly to PGE2. Upon further examination, two of the clones (C23 and C26) were also found to exhibit significant muscle myotube formation after reaching confluence, and three of the clones (C8a, C11, and C26) showed marked adipocyte differentiation after treatment with dexamethasone. Overall, these data add further supporting documentation to (1) the suspected ontogenetic relationships of osteoblasts to other connective tissue cells, and (2) the concept that osteoblastic cells associated with neonatal rat calvariae are in various stable stages of differentiation and developmental commitment.

Adipose Tissue↗
PubMed1991

Putrescine is involved in the vitamin D action in chick intestine.

We have reported that a single injection of 1 alpha,25-dihydroxyvitamin D3 into vitamin D-deficient chicks produces a marked increase of putrescine accumulation in the duodenum from two different sources, ornithine and spermidine. In the present study, the effects of putrescine depletion and its supplementation on duodenal villus length and calcium absorption were examined in newborn and 5-week-old chicks. Administering either alpha-difluoromethylornithine, a specific inhibitor of ornithine decarboxylase, or N1,N4-bis(2,3-butadienyl)-1,4-butanediamine, a specific inhibitor of polyamine oxidase, to newborn chicks significantly decreased the duodenal content of putrescine and calcium transport activity. The putrescine depletion also induced shortening of the duodenal villus length. The inhibition of calcium absorption and villus length in the putrescine-depleted chicks was almost completely restored by administering putrescine to the birds. The effect of the putrescine depletion and its supplementation on the duodenal villus length and the calcium absorption was reproduced in 5-week-old vitamin D-deficient chicks given vitamin D3 or 1 alpha,25-dihydroxyvitamin D3. These results clearly indicate that putrescine is somehow involved in the vitamin D action in maintaining the morphological and functional development of the intestinal villus mucosa.

Acetyltransferases↗
PubMed1991

Two flavonol glycosides from seeds of Camellia sinensis.

Two novel flavonol triglycosides, camelliaside A and B, have been isolated from seeds of Camellia sinensis. The structures were determined to be kaempferol 3-O-[2-O-beta-D- galactopyranosyl-6-O-alpha-L-rhamnopyranosyl]-beta-D-glucopyranoside and kaempferol 3-O-[2-O-beta- D-xylopyranosyl-6-O-alpha-L-rhamnopyranosyl]-beta-D-glucopyranoside on the basis of spectroscopic, chemical and enzymatic studies. These types of interglycosidic linkages, Gal(1----2)[Rha(1----6)]Glc and Xyl(1----2)[Rha(1----6)]Glc, have not been reported previously in flavone and flavonol glycosides.

Carbohydrate Sequence↗
PubMed1991

Recombinant human bone morphogenetic protein-2 stimulates osteoblastic maturation and inhibits myogenic differentiation in vitro.

The in vitro effect of recombinant human bone morphogenetic protein-2 (rhBMP-2) on osteogenic and myogenic differentiation was examined in two clonal cell lines of rat osteoblast-like cells at different differentiation stages, ROB-C26 (C26) and ROB-C20 (C20). The C26 is a potential osteoblast precursor cell line that is also capable of differentiating into muscle cells and adipocytes; the C20 is a more differentiated osteoblastic cell line. Proliferation was stimulated by rhBMP-2 in C26 cells, but inhibited in C20 cells. rhBMP-2 greatly increased alkaline phosphate (ALP) activity in C26 cells, but not in C20 cells. The steady-state level of ALP mRNA was also increased by rhBMP-2 in C26 cells, but not in C20 cells. Production of 3',5'-cAMP in response to parathyroid hormone (PTH) was dose-dependently enhanced by adding rhBMP-2 in both C26 and C20 cells, though the stimulatory effect was much greater in the former. There was neither basal expression of osteocalcin mRNA nor its protein synthesis in C26 cells, but they were strikingly induced by rhBMP-2 in the presence of 1 alpha,25-dihydroxyvitamin D3. rhBMP-2 induced no appreciable changes in procollagen mRNA levels of type I and type III in the two cell lines. Differentiation of C26 cells into myotubes was greatly inhibited by adding rhBMP-2. The inhibitory effect of rhBMP-2 on myogenic differentiation was also observed in clonal rat skeletal myoblasts (L6). Like BMP-2, TGF-beta 1 inhibited myogenic differentiation. However, unlike BMP-2, TGF-beta 1 decreased ALP activity in both C26 and C20 cells. TGF-beta 1 induced neither PTH responsiveness nor osteocalcin production in C26 cells, but it increased PTH responsiveness in C20 cells. These results clearly indicate that rhBMP-2 is involved, at least in vitro, not only in inducing differentiation of osteoblast precursor cells into more mature osteoblast-like cells, but also in inhibiting myogenic differentiation.

Alkaline Phosphatase↗