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Y Kajimoto

Publications and source records attributed to Y Kajimoto.

107 records · Page 6Linked to original sources
PubMed1991

Structure of the chicken insulin-like growth factor I gene reveals conserved promoter elements.

Insulin-like growth factor I plays a major role in cellular growth by mediating many of the actions of growth hormone. In mammals, IGF-I gene expression is complicated, as the single-copy gene is transcribed and processed into multiple mRNAs that encode at least two peptide precursors. Recent cDNA cloning studies have suggested that in chickens the organization of the gene might be simpler, and that comparative mapping might define essential features of IGF-I that are common to vertebrates. To achieve this goal, we have cloned and characterized the chicken IGF-I gene. The chicken gene is more compact than its mammalian homologues. It is composed of 4 exons which are distributed over 50 kilobases (kb) of chromosomal DNA and are transcribed and processed into mRNAs of 1.9 and 2.6 kb. As in the rat and human genes, the mature 70-amino acid IGF-I molecule is encoded within exons 2 and 3, while exons 1 and 4 contain NH2- and COOH-terminal extension peptides, respectively, and untranslated sequences. Both ends of the chicken gene are structurally heterogeneous. IGF-I mRNAs were found to have two regions of polyadenylation which mapped to exon 4 and were separated by approximately 0.7 kb. At the 5' end, several transcription initiation sites were identified within a 74-nucleotide portion of exon 1 that was found to be highly conserved between chicken and mammalian IGF-I genes. To test promotor function, chimeric genes were constructed linking fragments of chicken IGF-I 5'-flanking DNA to a promoterless reporter plasmid. Hybrid genes containing at least 0.6 kb of IGF-I enhanced expression of luciferase after transfection into SK-N-MC cells, a human line that synthesizes IGF-I mRNA. These observations represent the first thorough characterization of an IGF-I gene and provide an impetus for discerning the mechanisms by which IGF-I expression is regulated during growth, development, and differentiation.

Amino Acid Sequence↗
PubMed1991

Expression of insulin-like growth factor-I during chicken development.

We have investigated the expression of insulin-like growth factor-I (IGF-I) during ontogeny in the chick. IGF-I mRNA was first detectable in whole embryos on day 6, while serum IGF-I could be measured on day 9, the earliest time point examined. Serum IGF-I values rose 10-fold from about 3 ng/ml on day 10 to a prehatch peak of 30-35 ng/ml during days 15-17, and then declined to about 10 ng/ml at the time of hatching. On days 17 and 20 of incubation, IGF-I mRNA was detected in eye, skeletal muscle, and brain, but could not be found in liver or heart until after hatching. During the posthatch period, serum IGF-I rose from 10 ng/ml in the first week to 35-40 ng/ml during weeks 3-6, and liver IGF-I mRNA increased nearly 5-fold from weeks 1-7. The increases observed during weeks 1-3 correlated with a posthatch rise in serum GH from 21 to 37 ng/ml, although GH levels declined over the subsequent 4 weeks without an appreciable change in serum IGF-I values. By contrast, before embryonic day 12 no GH could be detected in the circulation, while IGF-I was 19 ng/ml on day 11. These observations suggest that there is both GH-dependent and GH-independent regulation of IGF-I gene expression in the chick, as has been found in mammals, and support the idea that IGF-I plays a role in chicken embryonic development.

Animals↗
PubMed1991

Prevention of posttransfusional non-A, non-B hepatitis by a screening test for hepatitis C virus antibody of donor bloods.

The preventive effect on posttransfusional non-A, non-B hepatitis (PTH) of screening out HCV-Ab positive blood and the prevalence of HCV-Ab-positive donor blood were examined. The incidence of HCV-Ab-positivity in donor blood A was 0.9% and that in donor blood B was 1.35%. The mean ALT and guanase levels were 11.5 +/- 5.8 and 0.58 +/- 0.24 IU/l in HCV-Ab negative blood and 17.3 +/- 7.9 and 0.84 +/- 0.23 IU/l in HCV-Ab-positive blood. Both levels were significantly higher in HCV-Ab-positive blood. These differences were considered to be nonspecific, but there may be some relationship between the levels of ALT and guanase in donor blood and the HCV carrier status. After adoption the screening test for HCV-Ab positive blood, there was no case of a definite diagnosis of PTH, although 4 patients (6.6%) suspected of developing PTH. So, the incidence of PTH was clearly lower than the lowest incidence before adoption of this test. Therefore, we conclude that screening for HCV-Ab in donor blood should be routinely used for prevention of PTH.

Blood Donors↗
PubMed1991

Dephosphorylation of the insulin receptor partially restores the decreased autophosphorylation in streptozotocin induced diabetic rats.

The insulin resistance seen in diabetes mellitus has been attributed partly to impaired autophosphorylation of the insulin receptor. It has been suggested that the phosphorylation of serine and/or threonine residues of the insulin receptor may reduce tyrosine autophosphorylation in streptozotocin-induced diabetic rats (STZ-D rats). To elucidate the mechanisms of decreased autophosphorylation of the insulin receptor in diabetic rats, we have investigated the effect of dephosphorylation of the insulin receptor by alkaline phosphatase on the insulin- and protein kinase-stimulating incorporation of 32P into the receptor of the liver from STZ-D rats. Both basal and insulin-stimulated autophosphorylations of the insulin receptor from STZ-D rats were significantly impaired to those from normal rats. Dephosphorylation of the insulin receptor by alkaline phosphatase resulted in an increase in insulin-stimulated autophosphorylation of the insulin receptor from STZ-D rats (43 +/- 13% to 66 +/- 14%, P less than 0.05), but not from normal rats (100% to 109 +/- 12%, NS). Although maximal autophosphorylation of the dephosphorylated insulin receptor was still lower in STZ-D rats than in normal rats, the increase in insulin-stimulated autophosphorylation of the insulin receptor from STZ-D rats by dephosphorylation was higher than that from normal (159.2 +/- 27.2% vs 108.0 +/- 12.4%, p less than 0.01), supporting the idea that the residues of the insulin receptor of STZ-D rats was highly phosphorylated.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaline Phosphatase↗
PubMed1990

Evolution of insulin-like growth factor I (IGF-I): structure and expression of an IGF-I precursor from Xenopus laevis.

By means of a cloning strategy employing the polymerase chain reaction, we have isolated and characterized cDNAs for Xenopus laevis insulin-like growth factor I (IGF-I). These cDNAs encode a primary IGF-I translation product of 153 residues that demonstrates considerable amino acid sequence similarity with IGF-IA peptides from other species. Fifty-seven of 70 residues of the mature protein are identical among human, rat, chicken, and Xenopus IGF-I, while less amino acid conservation is found at the COOH-terminus (25/35 identities) or at the NH2-terminus (24/48 identities) of the precursor protein. Despite the lower degree of structural similarity at the NH2-terminus, in vitro studies of IGF-I biosynthesis and proteolytic processing support a conserved function for the atypically long 48 residue NH2-terminal signal sequence in directing the nascent IGF-I peptide through the secretory pathway. The 5'-untranslated region of Xenopus IGF-I mRNA matches the human, rat, and chicken sequences in greater than 90% of 279 nucleotides. IGF-I mRNAs from all four species encode a conserved upstream open reading frame of 14 amino acids starting 240-250 nucleotides 5' to the translation start site, suggesting a possible role for this region in modulating IGF-I gene expression. The X. laevis IGF-I gene is transcribed and processed into three mRNAs of 1.6, 2.1, and 3.0 kilobases in liver, and IGF-I mRNAs can be detected in liver, lung, heart, kidney, and peritoneal fat of adult animals. These studies demonstrate that both the IGF-I protein precursor and potential regulatory regions of IGF-I mRNA have been conserved during vertebrate evolution, and indicate that like several other polypeptide growth factors, IGF-I may be of fundamental importance in regulating specific aspects of growth and development in all vertebrates.

Amino Acid Sequence↗
PubMed1989

Structure and expression of a chicken insulin-like growth factor I precursor.

Insulin-like growth factor I (IGF-I) is a 70 amino acid growth-promoting polypeptide whose sequence and functions have been highly conserved among mammals. As an initial step in defining the role of IGF-I in other vertebrate species, we have isolated and characterized an IGF-I cDNA from the chicken. This cDNA encodes a 153 amino acid primary translation product which resembles in structure and sequence the IGF-IA protein of mammals. There is strong amino acid conservation between chicken and mammalian IGF-I throughout the entire protein. Sixty of 70 amino acids are identical in mature IGF-I among the chicken, rat, and human peptides, with five differences being localized to the C domain, and two to the D region. A comparable degree of amino acid identity is found in the COOH-terminal extension peptide (28/35 residues). At the NH2-terminus, where there is more amino acid divergence (32/48 identities), the most 5'-AUG codon is the only methionine residue conserved among all three species, suggesting that it functions as the authentic translation initiation site, an observation supported by cell-free studies of biosynthesis and cotranslational proteolytic processing. The pattern of IGF-I gene expression appears to be simpler in chickens than in mammals, since a single predominant mRNA of 2.6 kilobases can be detected in liver polyadenylated RNA on Northern blots. In the chicken, as in rats and humans, IGF-I mRNA is synthesized in multiple tissues, including liver, brain, skeletal muscle, and heart.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1987

Effect of dexamethasone on the synthesis and degradation of insulin receptor mRNA in cultured IM-9 cells.

The effect of glucocorticoid (dexamethasone) on insulin receptor mRNA was examined in the IM-9 cell line by dot hybridization analysis using insulin receptor c-DNA probe (phINSR 13-1). Insulin receptor mRNA was found in a dose- and time-dependent manner, to increase during a 24-h culture with glucocorticoid. Although there has been some dispute about the effect of glucocorticoid on degradation of the insulin receptor itself, we have found glucocorticoid had no significant effect on the degradation rate of insulin receptor mRNA. These results suggest that glucocorticoid has the effect of increasing de novo synthesis of insulin receptor mRNA. But the molecular mechanism of glucocorticoid's effect still needs to be investigated.

Cell Line↗
PubMed1985

The effects of volume loading during epidural analgesia.

We have determined the effects of volume loading on the cardiovascular changes during epidural analgesia in 37 patients, who underwent various kinds of surgery. The patients were placed in 4 groups, depending upon the level of analgesia and utilization of volume loading with colloidal solutions. If the analgesia extended above Th4 we grouped them as "high epidural" and lower than Th5 level they were grouped as "low epidural". The cardiac output was measured through a Swan-Ganz catheter with thermo-dilution methods and cardiovascular variables were calculated by standard formulas. Under epidural block the most significant changes were a fall in blood pressure with decrease in cardiac output which were more pronounced during high epidural analgesia. Volume loading during the induction period with colloidal solutions would prevent the marked fall of blood pressure in half of cases studied, but in the other half the infusion was not effective for the prevention of fall in blood pressure. On every occasion over-loading effects on the right side of the heart were observed with the infusion of colloidal solutions. Also, a marked fall in systemic vascular resistance was observed with the infusion. In consequence the volume loading did not prevent the fall in arterial pressure. To manage the latter which was observed during epidural block, some sympathomimetic agents would be necessary with the volume loading. This approach would be much more important in patients with dehydration and high level of epidural analgesia.

Adult↗
PubMed1984

Metaraminol and dobutamine for the treatment of hypotension associated with epidural block.

In 14 patients undergoing major abdominal surgery, epidural analgesia was performed and cardiovascular changes were examined by insertion of Swan-Ganz catheters. To counteract the hypotensive episodes associated with epidural block, Dobutamine (1-3 micrograms/kg body wt min-1) and Metaraminol (0.5-1.5 micrograms/kg body wt min-1) in various doses were infused and the effects of these vasoactive agents were examined. Epidural analgesia decreased arterial pressure, pulmonary arterial pressure, pulmonary capillary wedge pressure and central venous pressure associated with marked decrease in cardiac index, stroke volume index, left ventricular and right ventricular stroke work without changes in systematic vascular resistance, pulmonary vascular resistance or heart rate. The infusion of Metaraminol caused a marked increase in arterial pressure, pulmonary arterial pressure, wedge pressure and central venous pressure. Calculated variables of stroke volume, systemic vascular resistance, left and right stroke work and cardiac work increased significantly. The infusion of Dobutamine caused a marked increase in arterial and pulmonary arterial pressure, wedge pressure, central venous pressure and cardiac index associated with those calculated changes of left and right stroke work and cardiac work, which were increased markedly. On the other hand, heart rate, stroke volume and pulmonary vascular resistance did not show any remarkable changes. Our study indicates that the fall in arterial blood pressure associated with epidural block may be due to marked decrease in cardiac output, and the infusion of Dobutamine is one of the desirable methods to counteract the hypotensive episode.

Adult↗
PubMed1976

Inhibition of multiple ovulation in hypophysectomized hens treated with gonadotrophins.

Administration of PMSG or FSH to hypophysectomized hens prevented the multiple ovulation (2-3 ova) induced by an OIH. Inhibition of multiple ovulation did not occur when FSH was injected 1/2-2 hr before the OIH injection. The results are believed to support the theory that withdrawal of FSH stimulation sensitizes a follicle to the OIH in the normal hen.

Animals↗
PubMed1975

Effects of gentamicin on the intestinal bacterial flora of rats.

1) Normal intestinal microbial flora (NF) in feces of rats were examined before and after administration of gentamicin (GM). Although GM caused no influence on NF after 6 hours, the number of NF decreased markedly 24 hours after GM, viz., the count of coliforms, enterococci and lactobacilli was reduced to 1/10-1/100 of the control value while proteus and fusobacteria declines in number down to 1/100-1/1,000 times as low as the control value. 2) The decreased count of NF tended to recover to some degree at the end of the 1st therapeutic week and the considerably recovered count continued thereafter indicating about 1/10 times as low as the control value until a 12-week experimental period, except that the count of lactobacilli returned to almost normal. 3) Susceptibility of coliforms isolated from GM-treated rats to GM was nearly equal to that of the bacteria isolated from the untreated control rats, which revealed no development of drug resistance to GM. 4) The increasing rate of body weight was higher in GM-treated rats than in the control, and the feed intake was consequently great in the former.

Animals↗
PubMed1975

Effects of gentamicin on the thyroid function of rats.

The effect of gentamicin (GM) on the thyroid function was investigated in relation with its stimulating action to the growth of rats at a very small dose level. The results may be summarized as follows: (1) Changes in 131-I-uptake of the thyroid after administration of GM were unremarkable. The change in wet weight of the thyroid was also unremarkable. Therefore, GM may not affect the thyroid itself. (2) GM-treated rats clearly showed a decrease in 131-I-triiodothyronine resine sponge uptake (trisorb test) as compared with the control animals, viz.,GM-treated rats indicated hypofunction of the thyroid. (3) Thyroxin (t4) levels in theserum, determined by 125-I-T4 resine sponge uptake (tetrasorb test), were apparentlylower in the GM-treated rats than in the control. (4) The thyroid function test for synthesis of the hormones revealed an increase in diiodotyrosine (DIT) value and decreases in 3, 5, 3'-triiodothyronine (T3) and T4 values in the GM-treated groups as compared with the values in the control. (5) In view of the above results iit was obvious that GM does not cause abnormalities on iodine-uptake, iodine oxidation, organic conversion to iodinated tyrosines, deiodination and thyroglobulin. In contrast, GM may induce abnormality on coupling reaction from DIT to T3 and T4 because the increase in DIT value and decreases in T3 and T4 values are seen following administration of GM. The whole of these facts seems to play an important role in stimulation to growth of rats after administration of the drug.

Adrenal Glands↗