Biomedical subjects

Noboru Saito

Publications and source records attributed to Noboru Saito.

9 recordsLinked to original sources

PubMed2005

Effect of water deprivation on aquaporin 4 (AQP4) mRNA expression in chickens (Gallus domesticus).

Aquaporin (AQP) 4 is a member of the AQP gene family of water-selective transport proteins. We studied the effect of water deprivation on AQP4 gene expression in chickens. The nucleotide sequence of a chicken aquaporin 4 (AQP4) cDNA that encodes a protein of 335 amino acids showed high homology to mammalian AQP4. Using Northern blotting analysis, AQP4 mRNA in chickens was observed as a band of approximately 5.5 kb in several tissues in addition to the hypothalamus, proventriculus, kidney, and breast muscle. Quantitative analysis by real-time RT-PCR analysis showed that the mRNA expression of AQP4 in the hypothalamus significantly increased after dehydration. On the other hand, the mRNA expression of AQP4 in the kidney significantly decreased after dehydration. This suggests that AQP4 may play a pivotal role in osmoregulation in the chicken brain.

Amino Acid Sequence↗

PubMed2005

Mechanisms of rolipram-induced increase in the incidence of mammary adenocarcinoma: histopathological study of a 104-week oral carcinogenicity study in female Sprague-Dawley rats.

The present study was carried out to elucidate the mechanisms behind an increase in the incidence of malignant or multiple mammary tumors as a result of oral administration of rolipram in a 104-week carcinogenicity study. The organs and tissues of Sprague-Dawley (SD) rats of both sexes, which had been subjected to a 104-week oral carcinogenicity study at doses of 0.2, 0.6 and 2.0 mg/kg, were examined. No treatment-related effects were seen in males; however, in females, there was a significant increase in the number of malignant or multiple mammary tumor bearers at a dose of 2.0 mg/kg. No other target organs were identified and the incidence of other tumor types were within the female control range. To clarify the mechanisms behind a rolipram-induced increase in the incidence of mammary adenocarcinoma at time points earlier than 104 weeks, the hormonal changes associated with pituitary adenoma were identified, and estrous cycling in the ovary, uterus, and vagina were examined in female rats treated with rolipram for 52 weeks. The plasma prolactin (PRL) concentration in all female groups exceeded the control value at Week 52, and all these differences were statistically significant. There was also a dose-dependent relationship with PRL-producing pituitary adenomas. Changes in estrous cycling in the uterus and vagina and a decrease in the size and number of corpora lutea in the ovaries of female rats treated with rolipram at 2.0 mg/kg for 52 weeks indicated that an increase in the estrus phase of the cycle corresponded to a marked decrease in the diestrus phase, which might result from the increased plasma estrogen concentration. Together, all of the above mentioned data suggest that rolipram not only stimulates an increase in the number and size of PRL adenomas in the pituitary gland but also in the estrus phase of the estrous cycle. These events might cause progression of the mammary gland tissues from hyperplasia to carcinoma.

Adenocarcinoma↗

PubMed2005

[Aging and magnesium].

The aim of this article is to clarify the relationships between aging or age-related diseases and magnesium (Mg). The mutation of mitochondrial DNA can occur in both aging and Mg deficiency, resulting in peroxidation, intracellular Ca(2+) accumulation and apoptosis. The capability against peroxidation decreases in aging and Mg deficiency. DNA polymerase I, RNA polimerase and DNA helicase require Mg for their activities. Under Mg deficiency the replication, transcription and translation of DNA become erroneous. The dysfunctions of vascular endothelial cell occur in aging and Mg deficiency. In comparison between adult and old rats using the rings of rat thoracic aortae, vasorelaxation by acetylcholine and isoproterenol is lower in old rats, but can be improved through high Mg concentration. Although women with menopause are suffered from osteoporosis due to estrogen deficiency, bone fragility increases with additive Mg deficiency. High Ca intake is recommended for women with menopause, but adequate Mg intake is necessary to lower dietary Ca/Mg ratio, because the high ratio prompts blood coagulation. About lipid metabolism Mg can play a statin-like activity. Mg deficiency is complicated with lifestyle-related diseases, osteoporosis, bone fragility, depression and elderly dementia.

Adult↗

PubMed2004

Serum laminin is an independent prognostic factor in colorectal cancer.

PURPOSE: We investigated laminin, an important extracellular matrix component, to elucidate mechanisms of invasion and metastasis in colorectal cancer, and whether preoperative serum laminin is a predictive marker of high-risk groups. METHODS: We measured preoperative serum laminin levels using a two-step sandwich enzymeimmunassay (EIA) method in 205 patients with colorectal cancer, 109 with colon cancer and 96 with rectal cancer, 52 with hepatic metastases, and 153 with no hepatic metastases. RESULTS: Mean serum laminin in patients with colon cancer was 606.3+/-260.2 ng/ml, significantly higher than that of 258.0+/-92.0 ng/ml in normal controls (P<0.0001). The positive rate was higher at 89.3% for laminin vs. 38.0% for carcinoembryonic antigen (CEA) and 19.5% for CA19-9. Mean serum laminin in patients with hepatic metastases was 668.0+/-274.7 ng/ml, significantly higher than that of 585.2+/-252.5 ng/ml in patients without hepatic metastases (P=0.0472). Survival rates were significantly lower in the high (> or = 520 ng/ml) than in the low laminin group (<350 ng/ml; P=0.0451). Univariate and multivariate analysis, using Cox's proportional hazard regression model, showed serum laminin is an independent prognostic factor in colorectal cancer, along with hepatic, pulmonary and peritoneal metastases. CONCLUSION: Preoperative serum laminin levels are a useful predictive marker of high-risk groups in colorectal cancer.

Adult↗

PubMed2004

Changes in mRNA expression of MMP-2 in the Müllerian duct of chicken embryo.

Although asymmetric development of the ovary and the oviduct is a unique characteristic in birds, the mechanism of asymmetric development still remains unclear. Recently, degradation of extracellular matrix has been suggested as an important factor related to the regression of the Müllerian duct in mammals. The present study was conducted to examine a possible role of metalloproteinase-2 (MMP-2) in the regression of the right Müllerian duct in the developing chicken embryo. Morphological changes in the Müllerian ducts were studied on day 15 of incubation and mRNA expresseion of MMP-2 was studied on days 12, 15, and 18 of incubation. Morphological observation demonstrated the disappearance of basement membrane in the right Müllerian duct which undergoes the regression. RT-PCR analysis showed that MMP-2 mRNA expression of the right Müllerian duct increased on days 15 and 18 of incubation coincidently with the time of regression. In the right Müllerian duct, regression was prevented by diethylstilbestrol treatment on day 4 of incubation and a coincident decrease in MMP-2 expression was observed when compared to the control group. These results suggest that MMP-2 may be involved in the regression of the right Müllerian duct in the female embryos of the chicken.

Animals↗

PubMed2004

Increased expression of elastolytic cysteine proteases, cathepsins S and K, in the neointima of balloon-injured rat carotid arteries.

The matrix-degrading activity of several proteases are involved in the accelerated breakdown of extracellular matrix associated with vascular remodeling during the development of atherosclerosis and vascular injury-induced neointimal formation. Previous studies have shown that the potent elastolytic cysteine proteases, cathepsins S and K, are overexpressed in atherosclerotic lesions in human and animal models. However, the role of these cathepsins in vascular remodeling remains unclear. In the present study, the expressions of cathepsin S and K and their inhibitor cystatin C were examined during arterial remodeling using a rat carotid artery balloon-injury model. The increase in both cathepsin S and K mRNA levels was observed from day 1 and day 3 through day 14 following the induction of balloon injury, respectively. Western blotting analysis revealed that both cathepsin S and K protein levels also increased in the carotid arteries during neointima formation, coinciding with an increase elastolytic activity assayed using Elastin-Congo red, whereas, no significant change in the expressions of cystatin C mRNA and protein was observed during follow-up periods after injury. Immunohistochemistry, Western blot, and in situ hybridization showed that the increase of cathepins S and K and the decrease of cystatin C occurred preferentially in the developing neointima. These findings suggest that cathepsin S and K may participate in the pathological arterial remodeling associated with restenosis.

Angioplasty, Balloon↗

PubMed2004

Bone mineral density, serum albumin and serum magnesium.

OBJECTIVES: This study explores clinical and laboratory abnormalities that contribute to the prevalence of bone fractures in frail and control elderly patients, to ascertain factors that relate to bone strength and fragility. METHODS: Patients were selected as free from renal failure and not taking supplements or medications that affect their magnesium status, and categorized according to their underlying diseases, sex and age, and evaluated by tests of bone strength. RESULTS: Findings, differentiating elderly patients on the basis of their magnesium, calcium, serum albumin, body mass, bone mineral density and their fracture occurrence were tabulated. CONCLUSION: Evidence is presented of low magnesium and albumin serum levels, especially in women with low bone density, as well as of low calcium and trace minerals.

Aged↗

PubMed2004

Differential alternative splicing expressions of telomerase reverse transcriptase in gastrointestinal cell lines.

Telomerase is a cellular RNA-dependent DNA polymerase that serves to maintain the tandem arrays of telomeric TTAGGG repeats at eukaryotic chromosome ends. One of the human telomerase components is hTERT, which has three alternative spliced sites that introduce eight isoforms of hTERT mRNA. The expression of these isoforms in gastrointestinal cell lines is unknown. We developed a PCR-based assay for detecting these splicing variants. In gastric and hepatocellular carcinoma cell lines, the gamma deletion variant and its combination variants, alpha- and gamma-, beta- and gamma-, and alpha-, beta- and gamma-deletion variants were frequently detected, while they were not detected in colorectal carcinoma cell lines. Our results provide important information of use for more detailed studies on the regulation of telomerase activity.

Alternative Splicing↗

PubMed2002

cDNA cloning and mRNA expression of Transformer 2 (Tra 2) in chicken embryo.

We report the cloning of a chicken Transformer 2 (Tra 2) cDNA that encodes a protein of 289 amino acids which are 97.9% identical to those of mammalian splicing factor, Tra 2. Tra 2 mRNA was expressed in chicken embryonic tissues and was observed as a band of 1.5 kb by Northern blot analysis. Whole mount in situ hybridization showed an mRNA expression of Tra 2 in telencephalon, mandible, hyoid arch, wing and leg buds as early as day 3.5 of incubation. These results suggest that the Tra 2 gene may play a role in organogenesis in the chicken embryo.

Amino Acid Sequence↗