Biomedical subjects

Y Takagi

Publications and source records attributed to Y Takagi.

At least 91 records · Page 5Linked to original sources

PubMed2000

Theoretical analysis of right gastroepiploic artery grafting to right coronary artery.

BACKGROUND: The right gastroepiploic artery (GEA) has been used as the second reliable arterial graft for coronary artery bypass grafting (CABG). However, concern regarding the flow competition with the recipient coronary artery has remained. METHODS: An application of in situ GEA grafting to the right coronary artery (RCA) was studied by using a theoretical model. The theoretical model of CABG was given variables; ie, the diameters and the lengths of both in situ GEA and proximal segment of the RCA, and the degree of proximal stenosis in the RCA. According to the range of these variables obtained from clinical data, the ratio of the GEA flow to the flow of the RCA distal to the anastomosis was calculated. RESULTS: Main factors to determine the flows in the two parallel paths were the inner diameters of both vessels, and the degree of the proximal stenosis. When the inner diameters of the GEA were 0.5 mm larger than that of the RCA, the GEA carried more than 50% of the total flow of the RCA distal to the anastomosis despite a moderate stenosis in the RCA. When the inner diameter of the GEA was equal to, or 0.5 mm smaller than, that of the RCA, the GEA flow was dominated by the native RCA flow unless the proximal stenosis was critical. CONCLUSIONS: If the inner diameter of the GEA is 0.5 mm larger than that of the RCA, CABG with the GEA can be applied more widely. If not, the application would basically be limited.

Coronary Artery Bypass↗

PubMed2000

Autoradiographic investigation of the effect of 1-hydroxyethylidene-1, 1-bisphosphonate on matrix protein synthesis and secretion by secretory ameloblasts in rat incisors.

Seven daily subcutaneous injections of 1-hydroxyethylidene-1, 1-bisphosphonate (HEBP) can induce enamel hypoplasia. Several enamel-free zones were observed along the crown-analogue side of rat incisors during the secretory stage of amelogenesis. Ameloblasts related to the enamel-free zones lay directly on the abnormally non-mineralized mantle dentine, whereas the adjacent ameloblasts, which were forming the enamel matrix layer, were associated with the region where mineralization of dentine was proceeding. The further purpose of this study was to investigate the synthetic and secretory activity of these two groups of ameloblasts and to trace the fate of the radioactively labelled proteins. [(3)H]-proline was administered to Wistar rats 12 h after the last injection of HEBP. Light-microscopic autoradiography was performed. Quantitative analysis indicated that the ameloblasts of the enamel-forming zones in the drug-treated group showed a distribution pattern of silver grains similar to that of the controls. The ameloblasts of the enamel-free zones also demonstrated incorporation of [(3)H]-proline at the same level. There was some labelling over the non-mineralized mantle dentine, which was supposed to indicate the penetration of ameloblast products. From these results, it is concluded that HEBP does not affect the ameloblast activity in protein synthesis. The complete failure of enamel-layer formation in some specific regions is probably due to the failure in protein secretion and protein deposition. This study provides additional evidence that the mineralization of dentine is an essential factor in successful enamel matrix secretion and deposition.

Ameloblasts↗

PubMed2000

Gene expression and immunolocalization of amelogenin in enamel hypoplasia induced by successive injections of bisphosphonate in rat incisors.

Successive injections of 1-hydroxyethylidene-1, 1-bisphosphonate (HEBP) in rats induce enamel hypoplasia. To elucidate the pathogenesis of this hypoplasia, male Wistar rats were daily injected with HEBP or physiological saline for 7 days. After the last injection, they were killed under anaesthesia and their maxillary incisors were examined using an in situ hybridization technique and immunohistochemical staining to detect the gene expression and localization of amelogenin protein, respectively. In the HEBP-injected rats, several islets of partially mineralized enamel were present along crown-analogous surface of the incisor in the secretory stage of amelogenesis and enamel-free zones existed between these islets. In situ hybridization demonstrated amelogenin gene expression over the ameloblasts facing the islets of the matrix enamel as well as over those of the enamel-free zones. Immunohistochemical studies using rabbit antiamelogenin antibody revealed positive reaction both in the enamel matrix of the control group and in the islets of enamel matrix of the HEBP-injected group. Some small granules immunoreactive to amelogenin antibody were found in the distal portions of the ameloblasts in the HEBP-injected rats. The results indicate that HEBP does not alter amelogenin gene expression over ameloblasts, or the protein's existence in enamel matrix. There appeared to be some accumulation of amelogenin in the HEBP-treated ameloblasts. It is therefore suggested that the enamel hypoplasia in this experiment may not be due to a disturbance in amelogenin synthesis but to a disturbance in a later process, presumably of protein secretion.

Amelogenin↗

PubMed2000

High galactosylation of oligosaccharides in umbilical cord blood IgG, and its relationship to placental function.

N-linked oligosaccharides on human serum IgGs have been reported to modulate IgG function. We studied umbilical cord blood to determine whether neonatal IgGs have characteristic structures related to developmental and pathological status. Oligosaccharide patterns of serum IgG from 45 umbilical cord blood samples were characterized by HPLC, and compared with those of serum IgG from 11 normal adults. Oligosaccharyl amines from purified IgG were released by recombinant N-glycanase, labeled with fluorescence reagent FMOC (9-fluorenylmethyl chloroformate), and analyzed quantitatively by high-pressure liquid chromatography (HPLC). Increased galactosylation was observed in cord blood. The ratio of galactosylated to non-galactosylated oligosaccharides on IgG was 7.90+/-3.92 (mean+/-S.D.) in cord blood, significantly higher than the ratio in adults (1.60+/-0.62, P<0.0001). There were weak but not significant correlations between the ratio and birth weight, gestation period, mother's age, and no correlation with serum IgG concentration. The ratio was lower for premature or intra-uterine growth retarded neonates. Our results, in conjunction with previous reports that galactosylated IgG stimulates Fc-mediated phagocytosis of monocytes, suggest that increased galactosylation of IgG enhances neonatal immunity.

Adult↗

PubMed2000

Molecular cloning and expression of an otolith matrix protein cDNA from the rainbow trout, Oncorhynchus mykiss.

The fish otolith is a hard tissue consisting of calcium carbonate and organic matrices. The matrix proteins play important roles in otolith formation, but little is known about the nature of these proteins. In this study, matrix proteins were extracted from the otoliths of rainbow trout, Oncorhynchus mykiss, and chum salmon, Oncorhynchus keta. EDTA-soluble matrix proteins were separated by SDS-PAGE, revealing two major components in the otoliths of both species with apparent molecular masses of 55 and 43 kDa. N-terminal and some internal amino acid sequences of the 55-kDa otolith matrix protein were determined. A cDNA fragment encoding this protein of O. mykiss was amplified by reverse transcription PCR using two degenerate primers designed from the amino acid sequences. A cDNA encoding this protein was obtained by screening a saccular cDNA library using the amplified cDNA fragment as a probe. Nucleotide sequence analysis revealed that the cDNA clone has a sequence of 2.5 kb and the open reading frame encoding 344 amino acid residues. Northern blot analysis showed that mRNA of this protein is expressed specifically in the sacculus, and consistently during the day.

Amino Acid Sequence↗

PubMed2000

Nitric oxide synthase inhibitor attenuates inflammatory lesions in the skin of zinc-deficient rats.

Skin lesions are common manifestations of zinc deficiency in humans and animals, but the pathogenic mechanisms have not been fully clarified. In the present study, a nitric oxide synthase inhibitor, NG-nitro-L-arginine methyl ester (L-NAME), was given to zinc-deficient (ZD) rats to see whether it prevents or delays the occurrence of skin lesions. Weanling male rats were given free access to a ZD diet (2 mg zinc/kg) for 4 wk to induce zinc deficiency. Control rats, including pair-fed (PF) and ad libitum (AL) groups, were given a diet supplemented with zinc (50.8 mg zinc/kg. L-NAME (0.3 g/L in drinking water) was given to some ZD rats for 3 wk, starting at the second week of their ZD dieting. Dermatitis of the extremities, balanitis, stomatitis, and alopecia appeared in ZD but not in AL and PF rats. Administration of L-NAME significantly reduced the frequency of cutaneous and mucocutaneous inflammatory lesions but did not prevent alopecia in the ZD rats. Reverse transcription polymerase chain reaction showed that inducible nitric oxide synthase mRNA was expressed in the paw skin of ZD but not of AL and PF rats. Evaluation of skin microvascular permeability by the Evans blue leakage technique indicated that L-NAME administration significantly attenuated extravasation of Evans blue in the paw skin of ZD rats. Furthermore, stains positive for terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling were condensed and diffusely distributed over the epidermis, dermis, and subcutaneous tissue of paws in ZD rats. ZD rats had intense cell infiltration and parakeratosis in the paw skin. L-NAME administration effectively prevented these morphologic changes. These results demonstrate that nitric oxide synthase inhibitor ameliorates inflammatory lesions of the skin in ZD rats.

Animals↗

PubMed2000

Differences among mechanisms of ribozyme-catalyzed reactions.

The catalytic properties of ribozymes depend on the sophisticated structures of the respective ribozyme-substrate complexes. Although it has been suggested that ribozyme-mediated cleavage of RNA occurs via a rather strictly defined mechanism, recent findings have clearly demonstrated the diversity of reaction mechanisms.

Acids↗

PubMed2000

Clinical results of implantation of an endovascular covered stent-graft via midsternotomy for distal aortic arch aneurysm.

UNLABELLED: We have been implanting endovascular stent grafts (EVG) via midsternotomy for distal aortic arch surgery since February 1997. The early clinical results are evaluated. METHODS: There were 11 true aneurysms (8 fusiform, 3 saccular) and one chronic type B dissection. The average age was 68 yr (63-81). EVGs were PTFE-covered two-8 bend Z stents in the first eight cases and made with the same stents and ultrathin woven Dacron grafts in the last four cases. RESULTS: Total arch replacement and aortocoronary bypass grafting were combined in one and two patients, respectively. The average retrograde cerebral perfusion time was 42+/-8 min. The cardiopulmonary bypass time averaged 211+/-26 min. All patients awoke early after operation (4.5+/-1.2 h). All but one case was extubated within 24h. There was no operative mortality, but paraplegia and cerebral infarction were complicated in one case each. Their maximum diameter (73.9+/-21.2mm) decreased significantly after operation (68.7+/-20.1mm) and one year thereafter (63.1+/-16.0 mm). True aneurysms were thrombosed completely. A chronic type B dissection revealed impending rupture due to false lumen infection one year after operation. The whole descending aorta replacement was performed but the patient died 6 months thereafter due to cerebro-vascular complication. CONCLUSION: Implantation of EVGs reduces operative invasion for distal arch surgery. This procedure should improve mortality, while long-term results have not been clarified.

Aged↗

PubMed2000

Regulation of cellular functions by nucleoside diphosphate kinases in mammals.

The role of nucleoside diphosphate (NDP) kinases in cell growth, differentiation, and tumor metastasis in relation to signal transduction was investigated. The essential role of NDP kinase in cell growth was validated by coupling between reduced NDP kinase levels, induced by antisense oligonucleotides, and the suppression of proliferative activity of a cultured cell line. In addition, because NDP kinase levels are often enhanced with development and differentiation, as has been demonstrated in postmitotic cells and tissues, such as the heart and brain, we further examined this possibility using the bone tissue (osteoblasts) and a cultured cell line PC12D. The enhanced NDP kinase accumulation was demonstrated in the matured osteoblasts in vivo and in vitro by immunohistochemistry. In PC12D cells, neurite outgrowth took place in NDP kinase beta-transfected clones without differentiation inducers, which was accompanied by prolongation of doubling time. Neurite outgrowth, triggered by nerve growth factor and a cyclic AMP analog, was down-regulated upon forced expression of inactive mutant NDP kinase by virtue of a dominant negative effect. NDP kinase alpha-transfected rat mammary adenocarcinoma cells (MTLn3) and nm23-H2-transfected human oral squamous cell carcinoma cells (LMF4) manifested reduced metastatic potential and were associated with an altered sensitivity to environmental factors, such as motility and growth factors. NDP kinase alpha, compared to NDP kinase beta, was involved in a wide variety of the cellular phenomena examined. Taken together, NDP kinase isoforms appear to elicit both their own respective and common effects. They may have an ability to lead cells to both proliferative and differentiated states by modulating responsiveness to environmental factors, but their fate seems to depend on their surrounding milieu.

Amino Acid Sequence↗

PubMed2000

A hypothesis to explain the occurence of inner myometrial laceration causing massive postpartum hemorrhage.

BACKGROUND: Inner myometrial lacerations were found in three patients who developed uncontrollable postpartum massive bleeding despite the usual treatment for uterine atony. Because all the patients suffered from hemorrhage shock and their medical status deteriorated, their uteri were surgically removed to stop bleeding. After removal, one of them died. Postpartum hemorrhage was caused by inner myometrial laceration. We hypothesized a cause of inner myometrial laceration, using the three resected uteri, an assumed model of the uterine body, and 34 women. METHODS: The subjects were 37 women, of whom three were patients with inner myometrial laceration, 23 were women without inner myometrial laceration who underwent cesarean section, and 11 were women in the first stage of labor. The three resected uteri were examined both macroscopically and microscopically. We measured the thickness of the wall of the uterine muscle at the widest point of the uterine corpus and the thickness of the myometrial wall at a transverse section of the uterine cervix, as well as the radius of the inner lumen at the widest point of the uterus in 23 women during cesarean section. We also measured the thickness of the myometrial wall at the widest point of the uterine corpus in 11 women at the end of the first stage of labor during ultrasonic examination. The data were then used to estimate the stress on the uterine muscle. RESULTS: The stress on the uterine cervix was stronger than that on the uterine corpus during labor. When the stress on the uterine muscle is stronger than a specific value, inner myometrial lacerations develop on the right and/or left side of the uterine cervix. These lacerations may involve large vessels. CONCLUSIONS: We have discovered another cause of postpartum hemorrhage which we have named inner myometrial laceration. These lacerations appeared to result from a strong stress on the uterine cervix caused by an abnormal rise in intrauterine pressure during labor.

Abruptio Placentae↗

PubMed2000

Distribution of non-collagenous dentin matrix proteins and proteoglycans, and their relation to calcium accumulation in bisphosphonate-affected rat incisors.

It has been reported that multiple injections of 1-hydroxyethylidene- 1,1-bisphosphonate (HEBP) to rats prevent mineralization of incisor dentin, thereby revealing high concentrations of calcium in the non-mineralized matrix of circumpulpal dentin. To identify the molecules responsible for calcium accumulation in circumpulpal dentin matrix, rats were injected daily with HEBP (8 mg P/kg) for 7 d, and the incisors processed for various histochemical and immunohistochemical staining of non-collagenous matrices of dentin. Cuprolinic blue reactions for proteoglycans (PGs) were equally distributed in non-mineralized matrix of mantle and circumpulpal dentin layers. Dentin sialoprotein (DSP) and osteopontin (OPN) immunoreactions were found in non-mineralized circumpulpal dentin matrix, but not in mantle dentin. In normal incisors, however, predentin matrix showing significant DSP immunoreactivity was negative for Ca-GBHA reactions. HEBP-affected, non-mineralized OPN immunopositive bone matrix was also non-reactive for calcium. From these observations, neither PGs, OPN nor DSP appear to be responsible for calcium accumulation in HEBP-affected circumpulpal dentin. Stains-all reactive component, possibly dentin phosphoprotein (DPP), only showed the same distribution as that of Ca-GBHA in both HEBP-affected and normal dentin matrix, implicating a possible contribution of DPP to calcium accumulation in circumpulpal dentin and, hence, to appositional mineralization of dentin.

Animals↗

PubMed2000

Coexistence of psoriasis and linear IgA bullous dermatosis.

Linear IgA bullous dermatosis (LABD) is characterized by IgA autoantibodies against components of the basement membrane zone (BMZ). A 97-kDa protein is one of the major autoantigens associated with this disease. We report a 68-year-old man who developed LABD after a 3-year history of psoriasis and in the context of active hepatitis C virus infection. He had been treated with cyclosporin for psoriasis for about 9 months. Histologically, there was a subepidermal blister containing neutrophils and eosinophils with lymphocytes infiltrating predominantly in the dermis. Direct immunofluorescent staining showed linear IgA deposition at the BMZ. The patient's IgA autoantibodies bound exclusively to the epidermal side of 1 mol/L salt-split normal human skin. Immunoblot analysis identified a 97-kDa autoantigen in epidermal extracts. This appears to be the first case of LABD with IgA autoantibodies against a 97-kDa autoantigen, associated with psoriasis and hepatitis C virus infection.

Aged↗

PubMed2000

Assessment of disease activity and extent by magnetic resonance imaging in ulcerative colitis.

BACKGROUND: We determined whether magnetic resonance imaging (MRI) could determine the activity and site of involvement in ulcerative colitis. METHODS: Colonoscopy, double-contrast barium enema and gadodiamide-enhanced MRI were performed prospectively in six patients with ulcerative colitis, including three females aged 10-22 years, both in the active and the remission stages. RESULTS: Characteristic findings of MRI in the active stage of ulcerative colitis were loss of haustral markings and thickening and contrast enhancement of the colonic wall. In five of six patients, the site of disease distribution determined by MRI was in accordance with that determined by colonoscopy. CONCLUSIONS: Gadodiamide-enhanced MRI is a safe and useful method of determining disease activity and extent in patients with ulcerative colitis.

Adolescent↗

PubMed2000

Immunohistochemical demonstration of cyclin D1 in bladder cancers as an inverse indicator of invasiveness but not an independent prognostic factor.

BACKGROUND: Cyclin D1 is essential for G1 progression through the cell cycle phase. It is a possible proto-oncogene whose aberrant expression may be responsible for the occurrence of some types of human neoplasms. The objective of the present study was to demonstrate immunohistochemically cyclin D1 expression in bladder cancer tissues and establish any relationship with the histologic findings and the clinical course. METHODS: Tissue from 102 patients with bladder cancers and bladder tissue from five normal subjects were used for an immunohistochemical study of cyclin D1 using the avidin-biotin complex method. RESULTS: Nuclear staining of cyclin D1 was found in 79 (77%) out of the 102 cases of bladder cancer. The five cases of normal epithelium had no immunostaining for cyclin D1. All grade 1 tumors were positive for cyclin D1. With the advance of tumor grade the incidence of cyclin D1 decreased. All pTa tumors stained positively for cyclin D1, whereas the positive staining rates of invasive tumors were 47% in pT1, 73% in pT2, 31% in pT3 and 0% in pT4 tumors. Although a univariate analysis revealed patients with lesions positive to cyclin D1 had more favorable survival rates than those with negative findings, a multivariate analysis showed that positivity for cyclin D1 is not an independent prognostic factor. No relationship was discovered between positivity for cyclin D1 and tumor recurrence in patients with superficial bladder cancers. CONCLUSIONS: These findings suggest that cyclin D1 demonstrated immunohistochemically could be used as an inverse indicator for the level of invasiveness of bladder cancer, but not as an independent prognostic factor.

Adult↗

PubMed2000

Maintenance of blood heparin concentration rather than activated clotting time better preserves the coagulation system in hypothermic cardiopulmonary bypass.

In cardiopulmonary bypass (CPB), despite heparin regimens in which the activated clotting time (ACT) is kept at more than 400 s, there is biochemical evidence of thrombin generation indicating activation of the coagulation system and increased fibrinolytic activity. Therefore, to reduce the coagulant activation has been one of the main issues in the improvement of CPB. The purpose of this study was to compare the heparin concentration with the ACT and to evaluate the effect of keeping higher heparin concentration on the coagulation and fibrinolytic systems during hypothermic CPB, employing moderate hypothermia (MHT) or deep hypothermic circulatory arrest (DHT). Heparin was either administered to maintain an ACT >400 s (ACT group) or to maintain a whole blood heparin concentration of 3 mg/kg (heparin group). At the lowest core temperature during CPB, the ACT and the heparinase ACT (unrelated to heparin concentration) were increased the most whereas the whole blood heparin concentration was less than half the initial concentration in both ACT groups of MHT and DHT. The thrombin-antithrombin III (TAT) content just after CPB in both MHT and DHT was significantly lower in the heparin group than in the ACT group. In conclusion, ACT does not reflect the whole blood heparin concentration during hypothermic CPB. Furthermore, maintenance of the higher heparin concentration during hypothermic CPB may suppress the activation of the coagulation system via thrombin inhibition. That effect was more remarkable in deep hypothermic CPB. Therefore, we believe that anticoagulation management during hypothermic CPB should be based on the maintenance of the higher blood heparin concentration.

Aged↗

PubMed2000

Significant detection of circulating cancer cells in the blood by reverse transcriptase-polymerase chain reaction during colorectal cancer resection.

OBJECTIVE: To analyze the clinical value of reverse transcriptase-polymerase chain reaction (RT-PCR) recognition of mRNA coding for carcinoembryonic antigen (CEA) and cytokeratin 20 in blood obtained from patients with colorectal carcinoma. SUMMARY BACKGROUND DATA: RT-PCR has been applied to identify very small numbers of tumor cells. Molecular detection is thought to provide useful information for the clinical management of perioperative prophylaxis of tumor cell implantation or postoperative adjuvant therapy regimens. METHODS: From 52 patients with colorectal cancer, peripheral blood specimens were obtained before and after surgical manipulation; also, a specimen of mesenteric venous blood draining the colorectal tumor was obtained just before tumor resection. Using cDNA primers specific for CEA and cytokeratin 20, RT-PCR was performed to detect tumor cells. Subsequently, the 52 patients were divided into two groups, a group positive for both CEA and cytokeratin 20 and a group negative for CEA, cytokeratin 20, or both. RESULTS: On the basis of 450 days of follow-up data, the PCR-positive group had a significantly shorter overall survival than the PCR-negative group only with the mesenteric venous blood specimens. Multivariate analysis indicated that detection of the simultaneous presence of CEA and cytokeratin 20 mRNA in mesenteric venous blood is a potent prognostic factor independent of the traditional pathologic parameters. Of the eight peripheral blood specimens found to be PCR-positive, five showed a change of PCR from negative to positive during surgery, and liver metastases developed 11 months later in one of these five patients. CONCLUSIONS: Molecular detection of both CEA and cytokeratin 20 mRNA in mesenteric venous blood may be of prognostic value for patients with colorectal carcinoma. Molecular detection in the peripheral blood at surgery suggests that hematogenic tumor cell dissemination is a common and early event and that surgical manipulation enhances this release of tumor cells into the circulation.

Adult↗

PubMed2000

Immunohistochemical detection of the Wilms' tumor gene (WT1) in epithelial ovarian tumors.

The Wilms' tumor gene WT1 plays multiple roles in the development of the genitourinary organs and Wilms' tumors. The aims of this study were to immunohistochemically evaluate WT1 expression in normal female genital tissues and in epithelial ovarian tumors and to look for correlations between WT1 expression and histologic subtypes and cell proliferation in epithelial ovarian tumors. In normal female genital organs, WT1 expression was recognized in ovarian surface epithelium, the lining of inclusion cysts, and tubal epithelium, but not in the cervical or endometrial epithelium. In epithelial ovarian tumors, serous tumors generally revealed a high WT1 expression. Among adenocarcinomas, serous carcinoma revealed a significantly higher WT1 expression than the other histologic subtypes. There were no significant correlations between the WT1 labeling index and the Ki-67 labeling index, and no significant difference in survival between those showing high and low WT1 expression among the malignant cases. These results suggest that WT1 expression may be related to cell differentiation, and that the histologic subtypes of epithelial ovarian carcinomas may differ considerably in their biological characteristics.

Adenocarcinoma↗

PubMed2000

Excitotoxic hippocampal injury is attenuated in thioredoxin transgenic mice.

Thioredoxin is a small, multifunctional protein with a redox-active disulfide/dithiol in the active site. Thioredoxin plays several important biologic roles both in intracellular and extracellular compartments with its redox-regulating and reactive oxygen intermediates scavenging activities. We assayed the seizure response and the excitotoxic hippocampal injury in thioredoxin transgenic and wild-type C57BL/6 mice. Seizure score after kainic acid treatment was significantly lower in thioredoxin transgenic mice. Seven days after kainic acid administration, the damage in the hippocampal CA1 and CA3 regions was significantly attenuated in thioredoxin transgenic mice. Thioredoxin and redox regulation play an important role in excitotoxic brain damage.

Animals↗