Biomedical subjects

K Saitoh

Publications and source records attributed to K Saitoh.

At least 55 records · Page 3Linked to original sources

PubMed2000

Quasi-unit-cell model for an Al-Ni-Co ideal quasicrystal based on clusters with broken tenfold symmetry

We present new evidence supporting the quasi-unit-cell description of the Al72Ni20Co8 decagonal quasicrystal which shows that the solid is composed of repeating, overlapping decagonal cluster columns with broken tenfold symmetry. We propose an atomic model which gives a significantly improved fit to electron microscopy experiments compared to a previous proposal by us and to alternative proposals with tenfold symmetric clusters.

Journal Article↗

PubMed2000

Survival-promoting activity of IL-7 on IL-2-dependent cytotoxic T lymphocyte clones: resultant induction of G1 arrest.

Interleukin-7 (IL-7) is essential for both T cell and B cell development. Recent studies have suggested that IL-7 also functions as a survival-promoting factor for resting and activated T cells. In this study we examined the effects of IL-7 on survival and cytotoxicity of tumor-specific CD8(+) cytotoxic T lymphocyte (CTL) clones established and maintained either with IL-2 alone or with a combination of IL-2 and IL-7. While the CTL clones cultured in IL-2 alone died around day 10, the CTL clones cultured in the presence of IL-2 and IL-7 survived for more than 4 weeks after seeding. The long-term survival of the latter was correlated with the presence of IL-7 in the medium. In addition, IL-7 alone prolonged survival of other IL-2-dependent CTL clones after the removal of IL-2. IL-7 maintained the CTLs in G1 arrest after a slight proliferation during the initial phase during which low-level but sustained DNA synthesis was observed. However, there was no direct correlation between DNA synthesis and enhancement of long-term survival by IL-7 as demonstrated by the inhibiting proliferation of the CTL clones with the protein kinase inhibitor genistein. During long-term survival in the presence of IL-7, the cytotoxic activities of the CTL clones decreased gradually to background levels although they were restored soon after the next passage. These results suggested that IL-7 had the ability to set machinery in motion against apoptosis in the IL-2-dependent CTL clones. Such an effect of IL-7 might play a role in vivo in the process leading activated T cells to the resting, that is, memory state.

Animals↗

PubMed2000

Mixed dust fibrosis and tuberculosis in comparison with silicosis and macular pneumoconiosis.

BACKGROUND: To assess the relationship between mixed dust fibrosis (MDF) and tuberculosis. METHODS: We performed a comparative analysis with MDF, silicosis, and macular pneumoconiosis (Mac), using autopsy records from 1975 to 1994. RESULTS: Prevalences of having tuberculosis among MDF, silicosis, and Mac were not significantly different, albeit a tendency of higher prevalence in silicosis. Cure rates of tuberculosis were, in order, silicosis < MDF < Mac (P=0. 085). Death rates associated with tuberculosis were, in order, silicosis > MDF=Mac (P=0.911). With respect to the two types of association with tuberculosis, i.e., combined type (tuberculopneumoconiosis) and complicated one (pneumoconiosis with tuberculosis); the former was significantly dominant in silicosis, the latter was significantly dominant in Mac, and intermediate in MDF. As a whole, the complicated type had a tendency of a higher cure rate than the combined type (P=0.071). Although the differences of profiles between the combined and complicated types were not statistically significant, the combined type had a tendency to have longer duration of exposure to dusts, earlier registration for treatment, higher profusion score, and earlier death compared with the complicated type. CONCLUSIONS: From our findings, MDF takes an intermediate position between silicosis and Mac regarding the relationship with tuberculosis. The type of association with tuberculosis rather than the kind of background pneumoconiosis seemed to be more important in light of responsiveness to the treatment.

Autopsy↗

PubMed2000

Quantitation by (1)H-NMR of dolichol, cholesterol and choline-containing lipids in extracts of normal and phathological thyroid tissue.

Proton magnetic resonance spectroscopy at 1.9 T was used to quantify dolichols, cholesterols, choline-containing phospholipids and double bonds in unsaturated acyl chains in lipid extracts of four types of thyroid tissue [normal (n = 27), papillary cancer (n = 15), adenoma (n = 13) and Basedow disease (n = 6)]. In normal thyroid the mean concentrations of dolichol, cholesterol and phospholipids were 1.2, 3.6 and 2.1 micromol/g wet weight, respectively. The concentrations of these lipids exhibited positive mutual correlations and positive correlations with patient age. The increase in dolichol in elderly human thyroid may be due to the accumulation of lysosomes and may help to compensate for the decrease in the activity of lysosomal enzymes and in thyroid hormone production and release. Dolichol concentrations were significantly lower in papillary cancer (0.4 micromol/g) and Basedow disease (0.3 micromol/g) compared to normal thyroid (p < 0.01 and p < 0.05, respectively), while cholesterol was enhanced only in cancer tissue (10.7 micromol/g). Benign adenoma exhibited normal levels of both dolichol and cholesterol. These results suggest that the synthesis and accumulation of isoprenoids are normal in adenoma but not in cancer.

Carcinoma, Papillary↗

PubMed2000

Comparison of the effects of amrinone, milrinone and olprinone in reversing bupivacaine-induced cardiovascular depression.

BACKGROUND: Increasing evidence indicates that amrinone, a phosphodiesterase fraction III (PDE-III) inhibitor, has relative efficacy as an initial treatment for cardiovascular depression after bupivacaine in an experimental setting. This study was performed to compare the cardiovascular effects of the other new PDE-III inhibitors, milrinone and olprinone, with those of amrinone in reversing bupivacaine-induced cardiovascular depression. METHODS: In sevoflurane-anaesthetized dogs, bupivacaine was infused intravenously at 1 mg x kg(-1) x min(-1) until mean arterial pressure fell to 60 mmHg or less. The dogs received either amrinone (2 mg x kg(-1)), milrinone (0.2 mg x kg(-1)), olprinone (0.12 mg x kg(-1)) or 0.9% saline (0.5 ml x kg(-1)). RESULTS: Amrinone, milrinone and olprinone improved left ventricular systolic and diastolic function, resulting in an increase in cardiac index. The most significant difference observed among the three drugs was the change in heart rate (HR) after treatment. Milrinone significantly increased HR, but olprinone did not. CONCLUSION: Milrinone and olprinone are as effective as amrinone in reversing bupivacaine-induced cardiovascular depression.

Amrinone↗

PubMed2000

Involvement of natural killer cells in patients with myelodysplastic syndrome carrying monosomy 7 revealed by the application of fluorescence in situ hybridization to cells collected by means of fluorescence-activated cell sorting.

Monosomy 7 is the most frequent chromosome abnormality among patients with secondary myelodysplastic syndrome (MDS). We used fluorescence in situ hybridization (FISH) and fluorescence-activated cell sorting (FACS) in order to clarify the lineage involvement. Four patients, three with de novo MDS and one with secondary MDS, were enrolled in this study. Monosomy 7 was observed in pluripotent stem cells (CD34(+)Thy-1(+)), and in B (CD34(+)CD19(+)) and T/natural killer (NK) progenitors (CD34(+)CD7(+)). The number of abnormal cells of B (CD19(+)) and T (CD3(+)) cells was below the cut-off value, but approximately 60% of the NK cells (CD3-CD56(+)) contained monosomy 7 in three of the patients.

Aged↗

PubMed2000

Effect of intraportal adoptive immunotherapy on liver metastases after resection of pancreatic cancer.

BACKGROUND: The prognosis of patients with resected pancreatic cancer remains poor. This study evaluated the effect of adoptive immunotherapy (AIT) using intraportal infusion of lymphokine-activated killer (LAK) cells after curative resection and intraoperative radiation therapy (IORT) on advanced pancreatic cancer. METHODS: Twenty-nine consecutive patients with advanced pancreatic cancer (Japan Pancreas Society stage III or IV) were divided into two groups. The control group (n = 17) underwent tumour resection and IORT. The treatment group (n = 12) underwent resection, IORT and intraportal infusion of LAK cells combined with recombinant interleukin 2 (rIL-2). The incidence of liver metastasis and the survival rate of these two groups were compared. RESULTS: Although the overall survival between groups was not statistically different (P = 0.082), there were more patients (four) alive 3 years after operation in the test group (36 per cent versus zero), and the incidence of liver metastases in the treatment group was significantly lower (three of 12 versus ten of 15; P < 0.05). LAK therapy influenced survival positively in multivariate analysis. CONCLUSION: These preliminary observations suggest that AIT warrants further study as a possible adjuvant for patients undergoing curative resection and IORT for pancreatic cancer.

Combined Modality Therapy↗

PubMed2000

Application of efficient and specific gene transfer systems and organ culture techniques for the elucidation of mechanisms of epithelial-mesenchymal interaction in the developing gut.

Epithelial-mesenchymal interactions are very important in the development of the vertebrate gut. In the avian embryonic stomach (proventriculus), expression of embryonic chick pepsinogen (ECPg) gene, which is specific to developing glandular cells in stomach epithelium, is regulated by mesenchymal influence. Molecular mechanisms of tissue-specific transcriptional regulation of the ECPg gene and the molecular nature of the mesenchymal signals were analyzed using a combination of the classic organ culture system and gene transfer strategies. In the present review, three methods for the introduction of DNA into tissues are described: lipofection, electroporation and retroviral infection, and characteristics of each system are discussed.

Animals↗

PubMed2000

Analysis of cartilage maturation using micromass cultures of primary chondrocytes.

A micromass culture (MM-C) system of primary immature chondrocytes for functional analysis of soluble factors involved in the maturation step of cartilage was previously developed. Ectopically expressed BMP-2 was shown to induce the expression of the Ihh and Noggin genes. Here it is demonstrated that, upon longer culture, secreted bone morphogenetic protein-2 (BMP-2) further promotes the maturation step as judged by the induction of type X collagen and BMP-6 expression, which are known to be detectable in the later phase of cartilage maturation. Induction of all of these genes by secreted BMP-2 was not inhibited by ectopic expression of parathyroid hormone-related peptide (PTHrP) induced by retrovirus vector infection, although the same virus vector showed strong inhibitory effects on the expression of type X collagen gene or alkaline phosphatase activity in mature chondrocytes. These results suggest that the maturation-promoting activity exhibited by BMP-2 is dominant over the suppressive effect of PTHrP in immature chondrocytes. When the BMP-6 gene was introduced into the same virus vector as that used for BMP-2, it induced the same sets of genes (Ihh, Noggin, type X collagen and endogenous BMP-6) as BMP-2 did. These results also suggest that BMP-6 would autonomously maintain and/or promote a later stage of chondrocytic maturation.

Animals↗

PubMed2000

Expression of cytokeratin 1, 5, 14, 19 and transforming growth factors-beta1, beta2, beta3 in osteofibrous dysplasia and adamantinoma: A possible association of transforming growth factor-beta with basal cell phenotype promotion.

To elucidate the precise origin and characteristics of the epithelial components of osteofibrous dysplasia (OF) and adamantinoma (AD), the expression of transforming growth factor (TGF)-beta1, beta2 and beta3 and cytokeratin (CK) subtypes were studied in five cases of AD and 18 cases of OF by immunohistochemistry. CK1 was expressed in 10 out of 18 OF cases; CK5 was expressed in one OF case; CK14 was positively stained in 10 cases of OF; CK19 was positively stained in 16 OF cases; CK1 was expressed in three out of five AD cases; CK5 was expressed in one case of AD; CK14 was positively stained in four AD cases; and CK19 was positively stained in five AD cases. In OF, TGF-beta1, beta2 and beta3 were expressed in both fibroblasts and osteoblasts. In AD, TGF-beta1, beta2 and beta3 were expressed in both epithelial and fibrous components. These results suggest that epithelial components of AD and OF share epidermal characteristics, CK1, express basal cell phenotype and cytokeratins 5, 14 and 19. In addition to these epithelial characteristics, strong immunoreactivity for TGF-beta poses the possibility of TGF-beta promotion of basal cell phenotype expression for the epithelial components in OF and AD.

Adolescent↗

PubMed2000

The fiberscopic findings of the epidural space in pregnant women.

BACKGROUND: The spread of epidural analgesia is facilitated by pregnancy. Changes in the epidural structure during pregnancy may affect the spread of analgesia in pregnant women. To investigate the changes in the epidural space produced by pregnancy, the authors performed epiduroscopy in pregnant women. METHODS: Using a flexible fiberscope, the authors evaluated the epidural space in 73 women undergoing lumbar epidural anesthesia. Patients were classified into three groups: a nonpregnant group (n = 21), a first trimester pregnant group (8-13 weeks, n = 23), and a third-trimester pregnant group (27-39 weeks, n = 29). A 17-gauge Tuohy needle was inserted using the paramedian technique and the loss-of-resistance method with 5 ml air. The epiduroscope was introduced into the lumbar epidural space via the Tuohy needle and was advanced approximately 10 cm in a cephalad direction from the needle tip within the epidural space. The differences in the epidural space among the three groups then was evaluated. RESULTS: The epiduroscopy showed that the epidural pneumatic space, after injection of a given amount of air, was narrower and the density of the vascular network greater in the third-trimester group than in the other two groups. The amount of engorged blood vessels was greater in the third and first trimester groups than in the nonpregnant group. The amount of bleeding at the needle tip and the amount of fatty and fibrous connective tissue did not differ among the three groups. CONCLUSIONS: Epidural blood vessels become engorged in the first trimester; the density of the vascular networks increase in the third trimester. These changes in the epidural space during pregnancy may affect the spread of epidural analgesia in pregnant women.

Adult↗

PubMed2000

Distinction of space groups (I23 and I2(1)3) and (I222 and I2(1)2(1)2(1)) using coherent convergent-beam electron diffraction

Convergent-beam electron diffraction (CBED) is well known as a powerful tool to determine space groups of crystals. However, it cannot distinguish several sets of space groups. It is shown theoretically that the coherent CBED method can distinguish between space groups (I23 and I2(1)3) and between (I222 and I2(1)2(1)2(1)), which belong to indistinguishable sets. It is demonstrated by computer simulations that the relative arrangement of 2-fold-rotation and 2(1)-screw axes can be distinguished by examining the relative phases of specific reflections through the interference fringes of coherent CBED patterns. This fact implies that these space groups can be distinguished by the coherent CBED method.

Journal Article↗

PubMed2000

BMPs are necessary for stomach gland formation in the chicken embryo: a study using virally induced BMP-2 and Noggin expression.

Epithelial-mesenchymal interactions are necessary for the normal development of various digestive organs. In chicken proventriculus (glandular stomach), morphogenesis and differentiation of the epithelium depend upon the inductive signals coming from underlying mesenchyme. However, the nature of such signals is still unclear despite extensive analyses carried out using experimental tissue recombinations. In this study we have examined the possible involvement of bone morphogenetic proteins (BMPs) in the formation of stomach glands in the chicken embryo. Analysis of the expression patterns of BMP-2, -4 and -7 showed that these BMPs were present in the proventricular mesenchyme prior to the initiation of the proventricular gland formation. BMP-2 expression, in particular, was restricted to the proventriculus among anterior digestive organs. Virus-mediated BMP-2 overexpression resulted in an increase in the number of glands formed. Moreover, ectopic expression of Noggin, which antagonizes the effect of BMPs, in the proventricular mesenchyme or epithelium, led to the complete inhibition of gland formation, indicating that BMP signals are necessary for the proventricular gland formation. These findings suggest that BMPs are of prime importance as mesenchymal signals for inducing proventricular glands.

Animals↗

PubMed2000

The concentric structure of the developing gut is regulated by Sonic hedgehog derived from endodermal epithelium.

The embryonic gut of vertebrates consists of endodermal epithelium, surrounding mesenchyme derived from splanchnic mesoderm and enteric neuronal components derived from neural crest cells. During gut organogenesis, the mesenchyme differentiates into distinct concentric layers around the endodermal epithelium forming the lamina propria, muscularis mucosae, submucosa and lamina muscularis (the smooth muscle layer). The smooth muscle layer and enteric plexus are formed at the outermost part of the gut, always some distance away from the epithelium. How this topographical organization of gut mesenchyme is established is largely unknown. Here we show the following: (1) Endodermal epithelium inhibits differentiation of smooth muscle and enteric neurons in adjacent mesenchyme. (2) Endodermal epithelium activates expression of patched and BMP4 in adjacent non-smooth muscle mesenchyme, which later differentiates into the lamina propria and submucosa. (3) Sonic hedgehog (Shh) is expressed in endodermal epithelium and disruption of Shh-signaling by cyclopamine induces differentiation of smooth muscle and a large number of neurons even in the area adjacent to epithelium. (4) Shh can mimic the effect of endodermal epithelium on the concentric stratification of the gut. Taken together, these data suggest that endoderm-derived Shh is responsible for the patterning across the radial axis of the gut through induction of inner components and inhibition of outer components, such as smooth muscle and enteric neurons.

Animals↗

PubMed2000

Highly repetitive elements from Chinese bitterlings (genus Rhodeus, Cyprinidae).

We have isolated and characterized several highly repetitive DNA elements from two species of Chinese bitterlings, Rhodeus atremius suigensis and R. ocellatus ocellatus. They comprise a partly interspersed and partly tandem repetitive family of about 1.0 to 1.3 kb in length. Individual elements showed considerable length variation, but genomic Southern blotting revealed two major length groups. Their restricted presence of these elements among related species and relative copy number differences indicated rapid change of genome structure in this group of fish. The isolated elements may be useful landmarks for further chromosomal studies.

Animals↗

PubMed2000

Effects of hard tissue-related hormones on the intracellular calcium ion of the rat odontoblasts.

We examined the effects of PTH, calcitonin (CT) and parotin subunit on the intracellular Ca2+ of odontoblasts using a chelate reagent, FURA2-AM. Rat CT (rCT), at a final concentration of 0.01 microM, induced a gradual lowering of Ca2+, and addition of ATP, in the presence of CT, resulted in a partial and short-lasting recovery of Ca2+. At higher concentrations, it caused a rapid decrease of Ca2+. CTs of other animal species showed similar effects. Human PTH (hPTH) added at concentrations of 0.01, 0.1 and 1 microM, caused no significant changes in intracellular Ca2+. Parotin subunit caused a rapid lowering of Ca2+ which was seen already at 0.01 microM. rCT added after treatment with hPTH caused an immediate decrease of Ca2+ to zero level, showing that CT action was enhanced by pretreatment with hPTH. This enhancement was also confirmed by addition of hPTH after rCT, where at 1 microM, it caused further acute decrease in Ca2+. After intracellular Ca2+ was lowered by CT pretreatment, parotin, at 0.1 microM, induced a further but gradual decrease of Ca2+. The present results, together with our previous study indicating that hPTH increased cAMP production and that CT inhibited the PTH action, made it clear that all the hormones affect odontoblasts, and that CT and parotin act via Ca-related signal transduction system, while PTH acts via cAMP-PKA-related cascade. Possible crosstalk of both systems was also suggested.

Adenosine Triphosphate↗

PubMed2000

[Evaluation of varicocele by ultrasonography through a water bag in the supine position].

Recently, ultrasonography has been widely used to evaluate varicocele. However, it is difficult to obtain reproducible scrotal images with a hand probe in the standing position. We, therefore, applied the water bag technique during ultrasonographic examination of the scrotal contents in the supine position. The ultrasonographic images thus obtained were compared with physical findings and scrotal scintigraphic findings. Forty-five varicocele patients diagnosed by palpation and ultrasonography were enrolled in this study. An ultrasonographic examination through a water bag in the supine position has the following advantages 1) it is easy to perform and stable images are obtained, 2) varicoceles that are not palpable can be detected and 3) examinations can be repeated both pre- and postoperatively. Of the 45 patients, 39 and 41 had positive findings on the ultrasonographic images and physical examinations, respectively. Four patients had negative findings on physical examination but positive findings on the ultrasonographic images. Thus, ultrasonographic images through a water bag in the supine position proved to be a useful method of confirming the hemodynamics in varicoceles.

Adolescent↗

PubMed2000

[Combined effect of S-1 and CDDP as a modulator for colon 26 liver metastasis].

S-1 is a novel oral anticancer drug, composed of tegafur (FT), gimestat (CDHP) and otastat potassium (Oxo) in a molar ratio of 1:0.4:1, based on the biochemical modulation of 5-fluorouracil (5-FU). In this study the combined effect of S-1 and low-dose CDDP as a modulator for colon 26 liver metastasis in mice was evaluated. In an experiment with S-1 (5 mg/kg/day: po) and CDDP (0.25 mg/kg/day: i.p.) for 14 days, the combined effects for both liver metastasis and tumor of spleen were not superior to those with S-1 or CDDP alone group. Body weight loss was not greater in the S-1 + CDDP group than in the control group. In an experiment with S-1 (5 mg x 2/kg/day: po) and CDDP (0.25 mg/kg/day: i.p.) for 7 days, the inhibitory effects of S-1 + CDDP of liver metastasis and tumor of the spleen were remarkable compared with the S-1 alone group. However a greater loss of body weight was seen in the S-1 + CDDP group than in other groups. This study suggests that low-dose CDDP might be a modulator of S-1 for colon 26 liver metastasis. Further study is needed to determine the optimum dose and duration of treatment.

Animals↗