Biomedical subjects

Y Okada

Publications and source records attributed to Y Okada.

At least 469 records · Page 26Linked to original sources

PubMed1998

Circulating vascular endothelial growth factor (VEGF) is a possible tumor marker for metastasis in human hepatocellular carcinoma.

Vascular endothelial growth factor (VEGF) is closely related to angiogenesis in various human cancers. However, little is known of its circulating levels in hepatocellular carcinoma (HCC). We examined circulating VEGF levels in chronic liver disease to assess their clinical significance. Plasma VEGF concentrations were determined, by enzyme immunoassay, in patients with chronic hepatitis (CH; n = 36), liver cirrhosis (LC; n = 77), and HCC (n = 86) for a cross-sectional study. Plasma VEGF levels in healthy controls (n = 20) and CH, LC, and HCC patients were 17.7 +/- 5.4 (mean +/- SD), 30.6 +/- 22.8, 34.4 +/- 27.0, and 51.1 +/- 71.9 pg/ml, respectively. The levels were significantly elevated in the HCC group, compared with the control, CH, and LC groups. Plasma VEGF levels in stage I, II, III, IVA, and IVB HCC patients were 27.6 +/- 16.1, 26.5 +/- 13.7, 35.8 +/- 15.3, 45.4 +/- 39.4, and 103.1 +/- 123.2 pg/ml, respectively. The stage IVB patients with remote metastasis showed significantly marked elevation compared with the patients at the other stages. Platelet numbers were weakly correlated with plasma VEGF levels in the HCC group. Plasma VEGF level was highly elevated in patients with HCC, particularly those with metastatic disease. We consider that plasma VEGF is a possible tumor marker for metastasis of HCC. Circulating VEGF may be derived mainly from the large burden of tumor cells, and partly from platelets activated by the vascular invasion of HCC cells.

Adult↗

PubMed1998

Expression of telomerase activity in human endometrium is localized to epithelial glandular cells and regulated in a menstrual phase-dependent manner correlated with cell proliferation.

Telomerase activity is observed in most malignant tumors and germ cells, whereas normal somatic cells usually do not express it. Human endometrium is composed of glandular and stromal components and exhibits dramatic changes in proliferative activity during the menstrual cycle, which is exquisitely regulated by estrogen function. We previously reported that normal human endometrium expresses telomerase activity. However, it remains unclear which of the above components are the major sources of telomerase activity and how levels of telomerase activity are regulated over the menstrual cycle. Quantitative analysis of telomerase activity revealed that it changes dramatically over the course of the menstrual cycle and is strictly regulated in a menstrual-phase-dependent manner. Maximal activity equivalent to that in endometrial cancer was present in late proliferative phase, and minimal activity in late secretory phase. Postmenopausal endometrium and endometrium treated with anti-estrogen drugs exhibited decreased telomerase activity. Testing isolated epithelial glandular cells and stromal cells, we found that telomerase activity was localized to epithelial glandular cells. In situ RNA hybridization analysis also revealed epithelial-specific expression of human telomerase RNA. In vitro analysis of cultured epithelial cells demonstrated that telomerase activity is correlated with epithelial proliferation but not affected by estrogen treatment. These findings suggest that expression of telomerase activity is specific to epithelial cells and linked to cell proliferative status. The involvement of estrogen in telomerase regulation remains to be elucidated.

Cell Division↗

PubMed1998

Three-graft technique for ascending aorta and total aortic arch replacement.

We have developed a procedure for total aortic arch replacement using three separate Hemashield grafts and establishing deep hypothermic circulatory arrest and continuous retrograde cerebral perfusion followed by antegrade cerebral perfusion. This method is technically simple and yields secure anastomoses.

Aorta↗

PubMed1998

Isolation and structural analyses of positional isomers of 6(1),6m-di-O-alpha-D-mannopyranosyl-cyclomaltooctaose (m = 2-5) and 6-O-alpha-(n-O-alpha-D-mannopyranosyl)-alpha-D-mannopyranosyl- cyclomaltooctaose (n = 2, 3, 4, and 6).

Eight positional isomers of 6(1),6m-di-O-alpha-D-mannopyranosyl-cyclomaltooctaose (gamma CD) (m = 2-5) and 6-O-alpha-(n-O-alpha-D-mannopyranosyl)-D-mannopyranosyl-gamma CD (n = 2, 3, 4, and 6) in a mixture of products from gamma CD and D-mannose by condensation reaction of alpha-mannosidase from jack bean were isolated by HPLC. The structures of four isomers of 6-O-alpha-(n-O-alpha-D-mannopyranosyl)-D-mannopyranosyl-gamma CD were elucidated by NMR spectroscopy. On the other hand, four positional isomers of 6(1),6m-di-O-alpha-D-mannopyranosyl-gamma CD were determined by LC-MS analysis of degree of polymerization of the branched oligosaccharides produced by enzymatic degradation with bacterial saccharifying alpha-amylase (BSA), and combination of BSA and glucoamylase. Similarly cyclomaltodextrin glucanotransferase also digested these isomers.

Carbohydrate Conformation↗

PubMed1998

Bronchiolar-alveolar carcinoma in a cow.

Bronchiolar-alveolar carcinoma was observed in the lung of an 8-year-old Holstein cow. Grossly, the lung contained multiple tumour masses, which were solid, yellowish-white in colour, and firm in consistency. These tumours also occurred in the liver, pancreas, uterus and lymph nodes in the thoracic, abdominal and pelvic cavities. Histologically, the masses were composed of abundant fibrous stroma and proliferating atypical cuboidal epithelial cells, occasionally forming glandular structures. Electron microscopy revealed that the neoplastic cells had microvilli and lamellar bodies in the cytoplasm, suggesting that they originated from immature respiratory epithelial cells differentiating towards either Clara cells or type II pneumocytes.

Adenocarcinoma, Bronchiolo-Alveolar↗

PubMed1998

Small volumes of enteral feedings normalise immune function in infants receiving parenteral nutrition.

BACKGROUND/PURPOSE: Parenteral nutrition (PN) is associated with a risk of septicaemia. This may be caused by impairment of immune function related to PN. The authors investigated the effects of the addition of enteral feedings to PN on the immune status of human newborn infants. METHODS: Ten surgical infants (age less than 6 months) requiring PN were studied in two consecutive phases: (A) after 31.1+/-6.0 days (mean +/- SEM) of PN with no enteral feeding (total PN); and (B) after 4.7+/-1.1 days from the addition of small volumes of enteral feeding to PN. Full blood count and liver function tests were not significantly different between phases A and B. A control group (n = 9) of infants receiving a normal enteral diet was also studied. Host bactericidal activity against coagulase-negative staphylococci (CNS) was measured by an in vitro whole blood model. Bacterial killing was measured after a 45-minute bacterial challenge using the Miles-Misra technique. Tumour necrosis factor-alpha (TNF-alpha) was measured by enzyme-linked immunosorbent assay (ELISA) after 2 hours of bacterial challenge. RESULTS: The lowest level of CNS killing (37.7+/-5.2%), was observed in patients receiving total PN. This increased significantly after the addition of small enteral feeds (52.0+/-4.6%, P < .005) approaching the levels measured in controls (65.1+/-3.4%). TNF-alpha production was low during total PN (1467+/-297 pg/mL) and rose significantly after the addition of minimal enteral feeds (4,661+/-1,311 pg/mL, P < .05). The increase in CNS killing after the addition of small enteral feeds in patients on PN was significantly correlated with the duration of enteral feeding (r = 0.8, P = .006). CONCLUSIONS: These results indicate that the introduction of small volumes of enteral feed improve the impaired killing of CNS and the abnormal cytokine response observed during total PN. This implies that stimulation of the gastrointestinal tract may modulate immune function in neonates and prevent bacterial infection.

Bacteremia↗

PubMed1998

Role of the pons in hypoxic respiratory depression in the neonatal rat.

The main purpose of this study was to evaluate the role of the pons in hypoxic respiratory depression (HRD) of the neonatal rat. Experiments were conducted using the isolated brainstem-spinal cord preparation of the neonatal rat (1-3 days old). The brainstem was transected at various levels. We found that ablation of the diencephalon decreased respiratory frequency (fR), and conversely, that ablation of the midbrain or pons increased fR. In the preparation with the pons intact (without the midbrain), hypoxia (superfusate PO2 = 56 mmHg) caused strong depression of respiratory activity, which was characterized by a steady decrease in fR and in integrated inspiratory burst amplitude (integral of Phr). In the preparation with the intact ventral pons (without midbrain and dorsal pons) we observed similar, though weaker, HRD. When the entire pons was ablated, integral of Phr was little depressed by hypoxia and thus, HRD was further attenuated. We conclude that the pons contributes importantly to the induction of hypoxic respiratory depression in the neonatal rat. Both the ventral and dorsal portions of the pons are involved in the control of hypoxic respiratory depression. In addition, we show that the respiratory modulatory functions of the diencephalon (facilitating) and midbrain (inhibitory) are already expressed at the time of birth.

Animals↗

PubMed1998