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Biomedical subjects

A Okada

Publications and source records attributed to A Okada.

At least 163 records · Page 9Linked to original sources
PubMed1998

Amino acid metabolism in pediatric patients.

As with energy requirements, protein requirements are relatively much greater in infants and decline progressively with age. Amino acid metabolism in pediatric patients is characterized by the following differences. The requirement for essential amino acids in neonates is larger than that in adults. Because of low activity of phenylalanine hydroxylase and cystathionase, hyperphenylalaninemia and hypermethioninemia tend to occur, whereas tyrosine and cysteine tend to be deficient. In addition to cysteine and tyrosine, histidine, lysine, arginine and taurine are considered as semiessential amino acids. Nowadays there are different kinds of amino acid formulas to satisfy these specific requirements, and most of these formulas are intended to normalize the plasma aminogram. However, the nutritional benefit of these formulas for growth and development is still not completely proven, and the pharmacological use for specific diseases is expected with some modification of these formulas.

Adult↗
PubMed1998

Expression of protooncogene c-kit and its ligand stem cell factor (SCF) in gastric carcinoma cell lines.

We examined 13 human gastric carcinoma cell lines for the expression of both c-kit and stem cell factor (SCF). Expression of mRNAs was detected by both Northern blot analysis and reverse transcriptase-polymerase chain reaction (RT-PCR), and expression of translated proteins was detected by western blotting. Using RT-PCR we confirmed the expression of c-kit in five (ECC12, TMK1, MKN7, GCIY, and HGC27) cell lines. Northern blot analysis showed coexpression of both c-kit and SCF in ECC12 and expression of SCF in five other (MKN74, MKN1 OKAJIMA, KATOIII, and TMK1) cell lines. SCF stimulated both tyrosine phosphorylation of c-kit and growth of ECC12, whereas it did not stimulate those of GCIY. The sizes of c-kit transcript and protein in GCIY were slightly smaller than those of the reported ones, suggesting the presence of a biologically inactive truncated form of c-kit in GCIY. The present study suggests that c-kit/SCF system might play an important role in the carcinogenesis and tumor growth of ECC12 and that the truncated form of c-kit in GCIY might not be associated with malignant transformation.

Blotting, Northern↗
PubMed1998

Expression and degeneration of tenascin-C in human lung cancers.

Tenascin-C is an extracellular matrix glycoprotein produced in response to epithelial-mesenchymal interactions during organogenesis and tissue remodelling. It has therefore been proposed as a stromal marker for epithelial malignancy. To test this hypothesis, 30 human lung cancers, presenting a variety of clinicopathological features, and six specimens of normal tissue were examined by Western and Northern blotting of tenascin-C protein and mRNA. The results obtained were: (1) elevated tenascin-C expression was detected in all 30 cases by Western blotting, with mRNA increase in 22 of them; (2) mRNA for a large isoform of tenascin-C, including an alternatively spliced sequence, was expressed in lung cancer tissues but not in normal lungs; and (3) metastasis to lymph nodes was frequently found in cases whose tenascin-C was degraded into small fragments. These results suggest that tenascin-C degradation can be used as a marker for metastatic potential of a tumour.

Adenocarcinoma↗
PubMed1998

Double-conditioning regimens consisting of thiotepa, melphalan and busulfan with stem cell rescue for the treatment of pediatric solid tumors.

Major dose-limiting factors of high-dose thiotepa (TEPA) and melphalan are life-threatening mucositis and neurotoxicity. To administer a maximum dose of these drugs safely and to obtain a maximum anti-cancer effect, a double-conditioning regimen with a single grafting, two cycles of administration of a combination of TEPA (300-600 mg/m2) plus melphalan (70-150 mg/m2) with a 1-week interval was attempted in 20 patients with pediatric advanced or chemotherapy-resistant solid tumors (seven rhabdomyosarcoma, four hepatoblastoma, three neuroblastoma and four other malignancy). Combinations of TEPA plus melphalan/busulfan (Bu) (8-10 mg/kg) and TEPA plus Bu were given to four and two patients with brain tumors, respectively. In an additional two patients, three cycles of drug administration were performed. According to the results of the dose-escalating study, the maximum tolerable doses of TEPA and melphalan for children aged 2 years old or older were 1000 mg/m2 and 280 mg/m2, respectively. Mucositis was dose-limiting. Renal toxicity was also dose-limiting in young children (<2 years old). There were two treatment-related deaths (7%) (fungal pneumonia and renal tubular acidosis). Among 13 patients who received high-dose chemotherapy during CR, 10 are alive with no evidence of disease (15-59 months, median: 35 months) and in 13 evaluable patients without CR, six are alive without regrowth of the disease (14-59 months, median: 39 months). Thus, these novel conditioning regimens allowed us to increase the dose intensity to nearly the maximum for each drug and seemed to reduce adverse effects compared to previously reported regimens with these drugs. With regard to the effect on outcome, the results of this study seem to be encouraging, but a further study on a larger number of patients is required.

Adolescent↗
PubMed1998

Thirty-eight years experience of malignant hepatic tumors in infants and childhood.

A description is given of therapeutic experiences with 39 cases of malignant liver tumors in infancy and childhood during the past 38 years. Of these patients, 9 not undergoing hepatic resection all died, while 18 (60%) of 30 patients treated by hepatic resection survived. When only patients with hepatoblastoma are considered, 14 of 24 patients are alive, although 3 of them had local recurrence and had lung metastasis. Among patients with other types of liver tumor, those with hepatocellular carcinomas (2 cases) and vascular neoplasms all died in a short period of time, whereas 2 with yolk sac tumor and one with metabolic pancreatic tumor are alive despite of tumor recurrence. In summary, the results of surgical treatment of malignant liver tumors in infancy and childhood, which formerly were poor, have been improved remarkably, which we owe mainly to: 1) advances in diagnostic imaging techniques (e.g., angiography, ultrasonography, CT and MRI) permitting early diagnosis, localization of tumor, visualization of the coursing of major vessels (particularly, hepatic artery & vein) and more accurate definition of resectability, 2) technical improvement of hepatic resection and 3) progress of chemotherapy mainly with cisplatin and adriamycin.

Adolescent↗
PubMed1998

Zinc deficiency enhances interleukin-1alpha-induced metallothionein-1 expression in rats.

This study investigated whether interleukin-1alpha-induced metallothionein gene expression is affected by zinc deficiency. Weaning male rats were fed a zinc-deficient (ZD) diet (2 mg zinc/kg) or a zinc-supplemented diet [50.8 mg zinc/kg; controls for the diet included pair-fed (PF) and ad libitum consumption groups (AL)] for 4 wk. All rats except those that served as controls for interleukin-1alpha administration, (injected with vehicle and killed at 0 h) were then injected subcutaneously with interleukin-1alpha (2 x 10(7) units/kg body wt) and killed at 3, 6, 12, 24 and 72 h after the injection. Compared with AL and/or PF rats, zinc depletion significantly reduced zinc concentrations in plasma and liver but not in kidney or intestine, and significantly reduced hepatic, renal, and intestinal metallothionein-1 mRNA levels analyzed by competitive reverse transcription-polymerase chain reaction (RT-PCR). Interleukin-1alpha injection reduced plasma zinc concentration and enhanced liver zinc concentration, but did not affect zinc levels in kidney or intestine. Metallothionein-1 mRNA was significantly elevated by interleukin-1alpha in liver, kidney and intestine of all groups; the levels in liver and kidney of ZD rats 6 h after the injection were significantly higher than those of AL or PF rats. Liver metallothionein protein levels were enhanced after interleukin-1alpha injection in both AL and ZD rats. Semiquantitative RT-PCR revealed significantly higher hepatic levels of interleukin-1 receptor type-I mRNA in ZD rats than in AL and PF rats but no differences in renal or intestinal tissues among groups before interleukin-1alpha challenge. In conclusion, zinc deficiency induces upregulation of metallothionein-1 gene expression in response to interleukin-1alpha challenge in rats.

Animals↗
PubMed1998

Geranylgeranylacetone, an anti-ulcer drug, stimulates hexosamine production in a rat gastric mucosal cell line through binding to a specific cytosolic protein.

An anti-ulcer drug, geranylgeranylacetone (GGA), stimulates hexosamine production in a rat gastric mucosal cell line (RGM-1). The aim of this study was to elucidate the mechanism of this action. The role of protein kinase A, inositol phospholipid turnover and tyrosine kinase in the stimulatory action of GGA on hexosamine production in RGM-1 was determined by observing cAMP production, [3H]-inositol phosphate turnover and western blotting of tyrosine phosphorylation, respectively. Any trophic effect of GGA on RGM-1 was also checked by [3H]-thymidine incorporation. Our experiments showed that GGA has no effect on cAMP production, inositol phospholipid turnover, tyrosine phosphorylation or DNA synthesis in RGM-1. Finally, a [14C]-GGA competitive receptor binding assay was performed on RGM-1 and we found that [14C]-GGA specifically bound to RGM-1 cytosolic protein. Although retinoic acid (RA), another polyisoprenoid compound significantly stimulated hexosamine production in RGM-1, we confirmed that the [14C]-GGA binding site in RGM-1 is different from the RA binding site. In summary, GGA stimulates hexosamine production in RGM-1 and this action is probably mediated through its binding to a specific cytosolic protein in RGM-1.

Animals↗
PubMed1998

Relationship between severity and symptoms of reflux oesophagitis in elderly patients in Japan.

Since information concerning reflux oesophagitis in the elderly is limited, particularly in Japan, the severity and symptomatic profiles of reflux oesophagitis in elderly patients were investigated. One hundred and nineteen patients with reflux oesophagitis found among 2278 endoscopy cases between 1993 and 1996 were investigated in this study. The patients were divided into two groups, elderly and non-elderly. The severity of reflux oesophagitis was estimated by the Los Angeles classification. The presence or absence of typical symptoms (heartburn and regurgitation) was determined by interview. Reflux oesophagitis was not only more frequently found in the elderly group, but was more severe than in the non-elderly. Although the degree of manifestation of typical symptoms was similar between the elderly and the non-elderly with high-grade oesophagitis, the elderly patients with mild reflux oesophagitis were less symptomatic than the non-elderly. Mild reflux oesophagitis in the elderly may be missed due to its rarity of typical reflux symptoms and a substantial number of elderly persons might have subclinical reflux oesophagitis.

Adult↗
PubMed1998

Accessibility control of variable region gene assembly during T-cell development.

T-cell development is a complex and ordered process that is regulated in part by the progressive assembly and expression of antigen receptor genes. T cells can be divided into two lineages based on expression of either an alpha beta or gamma delta T-cell antigen receptor (TCR). The genes that encode the TCR beta and gamma chains lie in distinct loci, whereas the genes that encode the TCR alpha and delta chains lie in a single locus (TCR alpha/delta locus). Assembly of TCR variable region genes is mediated by a site-specific recombination process that is common among all lymphocytes. Despite the common nature of this process, recombination of TCR genes is tightly regulated within the context of the developing T cell. TCR beta, gamma and delta variable region genes are assembled prior to TCR alpha variable region genes. Furthermore, assembly of TCR beta variable region genes is regulated within the context of allelic exclusion. The regulation of rearrangement and expression of genes within the TCR alpha/delta locus presents a complicated problem. TCR alpha and delta variable region genes are assembled at different stages of T-cell development, and fully assembled TCR alpha and delta variable region genes must be expressed in distinct lineages of T cells, alpha beta and gamma delta, respectively. We have developed several experimental approaches to assess the role of cis-acting elements in regulating recombination and expression of TCR genes. Here we describe these approaches and discuss our analyses of the regulation of accessibility of the TCR beta and TCR alpha/delta loci during T-cell development.

Animals↗
PubMed1998

Increased hepatocyte growth factor content in rat stomach during omeprazole treatment.

BACKGROUND AND AIMS: Hepatocyte growth factor (HGF) is a potent mitogen of gastric epithelial cells, and its production is stimulated during the healing of gastric mucosal lesions. In this study, the effect of a proton pump inhibitor, omeprazole, on the production and degradation of HGF in the stomach was examined to elucidate the mechanism of the omeprazole-induced acceleration of gastric mucosal healing. METHODS: Indomethacin-induced gastric mucosal lesions were induced in rats with or without omeprazole pretreatment. HGF gene expression and the content of HGF was investigated in the rat stomach. HGF degradation by gastric juice was also tested. RESULTS: In omeprazole-treated rats, the healing of gastric mucosal lesions was accelerated in comparison with those of untreated rats. Although omeprazole treatment did not enhance the indomethacin-induced increase in HGF gene expression, it significantly augmented the gastric HGF content. Furthermore, omeprazole increased the gastric content not only of the inactive but also of the active heterodimeric form of HGF, and this appeared to be due to the inhibition of the HGF degradation by gastric juice. CONCLUSION: Omeprazole-induced acceleration of gastric mucosal healing may be mediated at least in part by the reduced degradation of HGF in the stomach.

Animals↗
PubMed1998

[Molecular basis of Hirschsprung disease].

Hirschsprung disease (HSCR) is a congenital malformation caused by the absence of ganglion cells in the myenteric and submucosal plexuses of the gut. Recent studies have shown that mutations in the RET, glial-cell-derived neurotrophic factor (GDNF), endothelin-B receptor (EDNRB), endothelin-3 genes are responsible for the occurrence of aganglionosis. Those genes are involved in the development of neural crest derivatives. The RET gene mutation are found in 50% of familial cases and 15% of sporadic cases. The mutations in other genes were found under 10%. In addition to such a low detection rate of the mutations, incomplete penetrance of the mutation was found in all four genes. Those results support multifactorial or polygenic feature of Hirschsprung disease. The additional candidate genes responsible for this disease will be identified along the signaling pathway through RET and EDNRB.

Animals↗
PubMed1998

[Three-dimensional gadolinium-enhanced dynamic MRI of whole liver using spectrally selected enhanced fast gradient recall sequence].

Three-dimensional gadolinium-enhanced dynamic MRI of whole liver using the spectrally selected enhanced fast gradient recall sequence (spec IR-efgre3d) was performed in five patients with HCC. Ten HCC nodules were confirmed by CTA, CTAP and Lipiodol CT, and all of them were detected with dynamic MRI. MIP images reconstructed from 3D gadolinium-enhanced dynamic MR studies clearly showed the main portal vein and its branches in all cases. Portal vein thrombosis was also demonstrated with the MIP images.

Carcinoma, Hepatocellular↗
PubMed1998

[History of progress in nutritional assessment].

Progress in nutritional assessment is reviewed. 1) Initial period (1930-1959): The first nutritional assessment procedures were surveys designed to describe the nutritional status of populations on a national basis. The important relationship between nutritional status and health was well documented and awareness among surgeons and physicians of the importance of nutritional assessment increasing during the 1950s. Enteral nutrition techniques were established and research on parenteral nutrition started. 2) Established period (1960-1979): With the development of enteral and parenteral nutrition techniques, the determination of the nutritional status of individual patients took on new importance. New concepts and methods were devised and used in developing regions of the world and for the assessment of the nutritional status of hospitalized patients during the 1970s. 4) Developing period (after 1980): After 1980, investigators began to examine functional indices and combinations of parameters that would have prognostic value in order to determine the indications for clinical outcome. Many types of sophisticated equipment for assessing nutritional status became available and encouraged the development of a new concept of body composition. Despite the development of such new technologies, experienced clinicians were able to obtain a remarkable degree of agreement. Further education of all staff is essential in the clinical art of detecting the early and subtle changes of malnutrition.

History, 20th Century↗
PubMed1998

[Gd-DTPA enhanced multi-shot echo-planar MRI: improvement of contrast between metastatic liver cancer and liver parenchyma].

In six patients with metastatic liver cancer, spin-echo multi-shot echo-planar MR imaging 8/2000/80/1 (shot/TR/TE/excitation) of the liver was performed before and 30, 60, 90 and 120 sec after the intravenous injection of Gd-DTPA. Signal-to-noise ratios (SNR) of the liver tumor and liver parenchyma were measured in each phase. The contrast-to-noise ratios (CNR) between the tumor and liver parenchyma were also calculated. While the SNR of the tumor did not change after the injection of Gd-DTPA, the SNR of the liver parenchyma decreased and the CNR between the tumor and liver parenchyma increased.

Adult↗
PubMed1998

[Endothelin B receptor system and Hirschsprung disease].

Hirschsprung disease is a congenital malformation caused by the absence of ganglion cells in the myenteric and submucosal neural plexuses of gut. Mutations in the endothelin-Beta receptor (EDNRB) and endothelin-3(EDN3) genes as well as in the RET, glial-cell-derived neurotrophic factor and sox 10 genes have been shown to be responsible for this disease. These genes are involved in the development of intestinal neural crest derivatives. Recent studies have shown that EDNRB is expressed in neural crest cells before and through their migration into gut, whilst EDN3 is expressed in the mesenchymal cells. EDN3 acts as both a proliferative and also a differentiation factor in the development of neural crest cells. These reports support the hypothesis that EDN3 is an environmental factor which influences the migrating neural crest cells which express EDNRB.

Animals↗
PubMed1997

Pepsinogen C gene product is a possible growth factor during gastric mucosal healing.

We isolated, by the subtraction cloning method, a pepsinogen C (PGC) gene fragment (the sequence between the 968th and 1179th base pairs) from a rat gastric mucosal cDNA library as a cDNA clone encoding a substance that promotes growth of the normal rat gastric mucosal cell line RGM1. Northern blot analysis revealed that PGC gene expression was enhanced not only in acetic acid-induced chronic gastric ulcers but also in indomethacin-induced gastric mucosal lesions. PGC gene expression was also increased in the Helicobacter felis-infected stomachs. Thus, the PGC gene may play a role in gastric epithelial cell growth during gastric mucosal healing.

Acetic Acid↗