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Biomedical subjects

Y Seyama

Publications and source records attributed to Y Seyama.

At least 91 records · Page 5Linked to original sources
PubMed1995

Sexual dimorphism of lipids in Harderian glands of golden hamsters.

The Harderian gland of golden hamsters excretes alkyldiacylglycerol (ADG), the fatty acid and alkyl compositions of which differ between males and females. ADG in males contains mostly straight chain fatty acids, even- and odd-numbered, the major one being 15:0, while ADG in females contains iso- and anteiso-branched chain acids (34.0%). Iso-branching was found in both even- and odd-numbered acids, but anteiso-branching was found mostly in odd-numbered acids. The presence of propionic acid at the 3 position of the glycerol moiety in male ADG, and of isovaleric and 2-methylbutyric acids at the same position in female ADG was demonstrated by NMR spectrometry. Alkyl portions also exhibited sexual dimorphism in these lipids. ADG from males consisted of straight aliphatic chains, but branched chain components occupied almost half (45%) in ADG from females, and the branching resided at the iso- and anteiso-positions. The ADGs in glands from the two sexes were separated by Iatrobeads column chromatography into three and two subfractions, respectively. The fatty acid and alkyl compositions of these subfractions coincided with the above-mentioned results and with the behavior of the ADGs on thin-layer plates. These findings suggest that a sex hormone affects the metabolism of valine, leucine and isoleucine, and sexual dimorphism of ADGs occurs in the Harderian gland.

Animals↗
PubMed1995

Modulation of elastin expression by heparin is dependent on the growth condition of vascular smooth muscle cells: up-regulation of elastin expression by heparin in the proliferating cells is mediated by the inhibition of protein kinase C activity.

The effect of heparin on elastin expression in the proliferating and quiescent phases of growth of smooth muscle cells was studied. Heparin stimulated elastin synthesis and its mRNA level 2-3 fold in the proliferating cells while it inhibited the cell proliferation. The inhibition of cell proliferation and the stimulation of elastin expression by heparin in the proliferating cells were mimicked by a potent protein kinase C antagonist, H-7, but not by H-89, W-7, and HA1004, suggesting that the effect of heparin is mediated by the inhibition of protein kinase C. In contrast, heparin inhibited elastin synthesis and its mRNA level slightly but exhibited no effect on cell proliferation in the growth-arrested cells. This result indicates that heparin reciprocally affects elastin expression depending on the growth state of smooth muscle cells. Heparin thus exerts a complex influence on elastin expression in smooth muscle cells.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1995

Changes in the level of 7 alpha-hydroxy-3-oxo-4-cholestenoic acid in cerebrospinal fluid after subarachnoid hemorrhage.

A high concentration of a type of cholic acid, 7 alpha-hydroxy-3-oxo-4-cholestenoic acid, is observed in the content of chronic subdural hematoma. To investigate the possible causes, the level of this compound was measured in the cerebrospinal fluid of patients who underwent surgery for aneurysmal subarachnoid hemorrhage or non-hemorrhagic diseases. The maximum level was significantly higher in the aneurysmal subarachnoid hemorrhage patients, indicating that surgical intervention did not cause the postoperative increase in the level of this compound in the cerebrospinal fluid. Monitoring of plasma levels showed no postoperative increase. In vitro culture of a mixture of arterial blood and cerebrospinal fluid failed to show the de novo production of this compound. These results strongly suggest extrahepatic intracranial production of this cholic acid occurs in subarachnoid hemorrhage. The high concentration of this compound in both chronic subdural hematoma and subarachnoid hemorrhage suggests a possible role for 7 alpha-hydroxy-3-oxo-4-cholestenoic acid in intracranial hemorrhagic disorders.

Adult↗
PubMed1994

Important contribution of the methylene part of LTB4 toward binding affinity to the LTB4 receptors and rise in intracellular-free calcium concentration.

In order to examine a role of the C(16)-C(20) methylene part of leukotriene B4 (LTB4) toward the activation of leukocytes, we synthesized the LTB4-analogues in which the length of the C(16)-C(20) part of LTB4 is varied systematically while the two hydroxyl groups at C(5) and C(12) positions and the 6(Z), 8(E), 10(E) conjugated triene unit remained untouched. We examined their binding affinity to the LTB4 receptors present in the rat polymorphonuclear leukocytes (PMNLs) and their ability to raise intracellular-free calcium concentration ([Ca2+]i) in the rat PMNLs loaded with fura-2. As the length of the chain of LTB4 was increased or decreased one by one, the binding affinity to the LTB4 receptors diminished, and the analogues of more than three carbon atoms shorter chain were of about three log order less activity than LTB4. The biological potency as assessed in [Ca2+]i rises pararelled that of the binding affinity to the PMNL membrane. These results indicate that the C(16)-C(20) part of LTB4 plays important role for the activity. In a similar way we prepared the LTB4-analogues of a different chain length between C(2)-C(4) of LTB4 and tested their biological activity. We found that the C(2)-C(4) part of LTB4 also affects the activity.

Animals↗
PubMed1994

Distribution of cholinergic neuron-specific gangliosides (GT1a alpha and GQ1b alpha) in the rat central nervous system.

A newly developed mouse monoclonal antibody, GGR-41, was used to localize a novel species of gangliosides, GT1a alpha and GQ1b alpha, in the rat central nervous system. Intense immunoreactivity was found in the neuropil of the spinal cord dorsal horn, spinal trigeminal nucleus, solitary tract nucleus, superior colliculus, interpeduncular nucleus, hypothalamus and septal area. The results suggest that GT1a alpha and GQ1b alpha are expressed in the nerve terminals of a certain population of cholinergic fibers.

Animals↗
PubMed1994

Biosynthetic pathway for a new series of gangliosides, GT1a alpha and GQ1b alpha.

A new class of gangliosides, GT1a alpha and GQ1b alpha, were initially identified as cholinergic neuron-specific antigens in bovine brain. These gangliosides have in common alpha 2-6 NeuAc linked to the GalNAc residue in the gangliotetraose core structure. In this study, we have determined the biosynthetic pathways of GT1a alpha and GQ1b alpha using rat liver Golgi fraction. The results showed that GT1a alpha and GQ1b alpha were synthesized from GD1a and GT1b, respectively, by the action of a GalNAc alpha 2-6 sialyltransferase. It was also demonstrated that these two gangliosides were found to exist as extremely minor components in rat liver.

Animals↗
PubMed1994

Biochemical analyses of macromolecular matrix components in patients with pseudoxanthoma elasticum.

Two cases of pseudoxanthoma elasticum (PXE) were reported. Biochemical studies of collagen, glycosaminoglycan, and elastin content were performed using skin specimens from affected lesions. Hydroxyproline content was reduced approximately 46% and 24% in cases 1 and 2, respectively. The reduction in collagen content resulted from the reduction in the lower dermis, not from that in the upper dermis. Glycosaminoglycan content in PXE was also decreased, with a slight increase in the ratio of hyaluronic acid to dermatan sulfate. Isodesmosine content in PXE was increased 3.2- and 2.2-fold in cases 1 and 2, respectively. These results suggest that the major and primary biochemical changes in PXE are an increase in elastin content.

Adult↗
PubMed1994

Two species of antiganglioside antibodies in a patient with a pharyngeal-cervical-brachial variant of Guillain-Barré syndrome.

A patient with a pharyngeal-cervical-brachial variant of Guillain-Barré syndrome had anti-GT1a and anti-GD1a antibodies (IgG) in the serum. The activities of anti-GT1a antibodies were stronger than anti-GD1a antibodies and their activities declined later in the clinical course. These two different antibodies bound independently to each ganglioside in an absorption study with polystyrene beads coated with GT1a or GD1a.

Adult↗
PubMed1994

[Effect of traditional Chinese medicine (dai-saiko-to) on experimental calcinosis].

To clarify the anti-calcinosis actions of traditional Chinese medicine (Dai: Dai-saiko-to) and estradiol benzoate (E2), 7-week or retired (about 6-months-old) female rats were treated with Vit. D2 (1.75 x 10(5) I.U./kg b.w./day) for 4 days, and then were fed a basal diet containing Dai (at ten times the medical dose in humans) or were injected i.p. with E2 (at the medical dose in humans) for 6 weeks. The following results were obtained: 1) Dai did not improve Ca and P metabolism in experimental calcinosis of 7-week female rats; 2) in retired female rats, Dai decreased both P in the heart and the ratio of Ca to P in bone, similar to the treatment with E2. Dai, as well as E2, seemed to nomalize Ca and P metabolism disturbed by Vit. D2 treatment.

Animals↗
PubMed1994

Identification of new mutations in sterol 27-hydroxylase gene in Japanese patients with cerebrotendinous xanthomatosis (CTX).

Cerebrotendinous xanthomatosis (CTX) is a hereditary sterol storage disease associated with accumulation of cholesterol and cholestanol in various tissues, especially tendons and neural tissues. The biochemical defect that causes CTX is a deficiency of the mitochondrial sterol 27-hydroxylase which oxidizes the side chain of cholesterol in connection with formation of bile acids. Japan has a relatively high prevalence of CTX and more cases of the disease are found here than in any other country. In the present study two new different point mutations are described in the heme-ligand binding domain of the sterol 27-hydroxylase gene in three Japanese CTX patients and one CTX heterozygote. Two of the homozygotes as well as the heterozygote subject have a single base substitution of A for G at codon 441 [CGG (Arg) to CAG (Gln)]. Another homozygote has a transition of C to T at codon 441 [CGG (Arg) to TGG (Trp)]. These two different mutations result in two restriction fragment length polymorphisms (RFLPs) for the enzymes StuI or HpaII. We also assayed sterol 27-hydroxylase activity using skin fibroblasts derived from three CTX patients, one CTX heterozygote, and normal subjects. While two of the homozygous subjects have undetectable levels of the enzyme activity, one homozygous subject and one heterozygous subject have decreased levels of the enzyme activity, about 1.4% and 10% of normal, respectively. The results suggest that the newly identified point mutations in the sterol 27-hydroxylase gene could account for the sterol 27-hydroxylase deficiency in the Japanese CTX patients.

Adult↗
PubMed1993

Initiation of DNA synthesis in a high molecular weight fraction of Xenopus egg extract.

Xenopus egg extract was fractionated by gel-filtration column chromatography and DNA synthetic activity was examined using double-stranded DNA as a template. The major activity eluted had an apparent molecular mass of about 300 kDa. Product analyses showed that de novo DNA synthesis occurs with formation of replication bubbles, thereby suggesting that this fraction catalyzes the initiation of DNA replication. Activities of DNA polymerase alpha-primase and DNA helicase overlapped with the DNA synthetic activity, but the elution profiles of the enzymes differed from that of the DNA synthetic activity. Therefore, this 300-kDa fraction may contain a component which differs from the above enzymes yet is essential for initiation of DNA replication.

Animals↗
PubMed1993

Gallstone formation in cholestanol-fed mice.

We examined the effect of cholestanol (5 alpha-dihydrocholesterol) on cholesterol and bile acid metabolism in BALB/c mice. After feeding 1% cholestanol in the diet for 14 months, gallstones composed of 55% cholesterol and 45% cholestanol developed in 20% of the mice and were associated with mucosal inflammation and serosal vessel thickening of the gallbladder. Cholestanol concentrations increased 42-fold in the serum (0.17 versus 0.004 mg/ml) and 18-fold in the liver (0.55 versus 0.03 mg/g) as compared with control mice, whereas cholesterol declined 20 and 26% in serum and liver, respectively. Hepatic microsomal HMG-CoA reductase activity, reflecting cholesterol synthesis, rose 51% (from 7.2 to 10.9 pmol/mg/min). In contrast, hepatic microsomal cholesterol 7 alpha-hydroxylase activity, the rate-determining enzyme for bile acid synthesis, was severely depressed as compared with control mice (0.9 versus 2.2 pmol/mg/min). Discontinuing cholestanol from the diet for 1 month reduced the elevated serum and liver cholestanol concentrations and restored hepatic HMG-CoA reductase and cholesterol 7 alpha-hydroxylase activities to normal. These results demonstrate that cholestanol is absorbed, replaces cholesterol in serum and liver, causes increased cholesterol synthesis, but inhibits bile acid synthesis. The combination of increased cholesterol synthesis with decreased bile acid formation promotes gallstone formation in cholestanol-fed mice.

Animals↗
PubMed1993

1-Alkyl-2,3-diacylglycerol synthesis in primary culture cells of guinea pig harderian gland.

Using a primary culture system of guinea pig Harderian gland cells, we investigated the metabolism of a unique lipid: 1-alkyl-2,3-diacylglycerol containing methyl-branched fatty acids. The cells were obtained by collagenase digestion, and cells with lipid-droplets were collected by two-step centrifugation. We cultured these cells, and examined their lipid and fatty acid compositions. The de novo synthesis of lipids in these cells was studied as to the incorporation of [1(2)-14C]acetate and [U-14C]glucose. The major lipid proved to be 1-alkyl-2,3-diacylglycerol, as in tissue, and it contained a large amount of methylbranched fatty acids specific to this gland. The incorporation of [14C]acetate and [14C]glucose into 1-alkyl-2,3-diacylglycerol in the cultured cells amounted to 79.7 and 88.2% of the total incorporation into the lipid fraction, respectively. The incorporation of [14C]acetate into fatty acids in the cultured cells was detected for the chain lengths of C14 to C25. The activities of glycerol-3-phosphate dehydrogenase in the cultured cells and Harderian gland were lower than that in adipose tissue. These results confirm that cultured cells reflect the lipid metabolism originating in the Harderian gland and show that this culture system can serve as one part of the armamentarium for further study of this unique lipid metabolism.

Acetates↗
PubMed1992

Three types of Gi alpha protein of the guinea-pig lung: cDNA cloning and analysis of their tissue distribution.

cDNA clones encoding three types of Gi alpha, the alpha subunit of GTP-binding protein (Gi1 alpha, Gi2 alpha, and Gi3 alpha), were isolated from a cDNA library of the guinea-pig lung. Nucleotide sequence analysis revealed a high degree of homology with other mammalian Gi alpha cDNAs. By RNA blot analysis, the expression pattern of Gi1 alpha was more tissue-specific than those of other types of Gi alphas in the guinea-pig tissues examined. While Gi2 alpha and Gi3 alpha mRNAs were ubiquitously expressed in all tissues examined, Gi1 alpha mRNA was mainly expressed in the brain, lung and kidney. These results suggest that each Gi alpha protein may have a different role.

Amino Acid Sequence↗
PubMed1992

Identification of 7 alpha-hydroxy-3-oxo-4-cholestenoic acid in chronic subdural hematoma.

We detected a novel kind of bile acid in the content of chronic subdural hematoma. This substance was specifically found in chronic subdural hematoma, and not in subdural hygroma, which is pathologically similar except for the lack of capsular membrane. The compound was identified as 7 alpha-hydroxy-3-oxo-4-cholestenoic acid by high performance liquid chromatography, gas chromatography-mass spectrometry, and nuclear magnetic resonance spectrometry. The structure was confirmed by the comparison with the chemically synthesized compound. The average contents in chronic subdural hematoma were 658.09 +/- 137.53 ng/ml, while those in normal human plasma were 126.27 +/- 17.73 ng/ml. It was not detected in normal cerebrospinal fluid. The higher level in chronic subdural hematoma than human plasma strongly suggests the local, extrahepatic production of this type of C27 bile acids.

Bile Acids and Salts↗
PubMed1992

Platelet-activating factor (PAF) receptor in rat brain: PAF mobilizes intracellular Ca2+ in hippocampal neurons.

Platelet-activating factor (PAF), an alkylether phospholipid, is produced in the brain when it is subjected to various stimuli. Using a Xenopus oocyte expression system, we obtained evidence for functional PAF receptor mRNA expression in rat brain. The presence of the PAF receptor was confirmed and shown to be quite ubiquitous in the CNS by RNA blot and radioligand binding studies. To investigate the neuronal functions of PAF, intracellular Ca2+ increase elicited by nanomolar PAF application was analyzed in cultured rat hippocampal cells. Fractions of NMDA-responsive cells and non-NMDA-responsive cells were shown to respond to PAF, suggesting a potential role for PAF in the Ca2+ signaling pathway in the hippocampus.

Animals↗
PubMed1992

Effect of Harderian gland-derived growth factor on the growth of cornea stromal cells.

To investigate the physiological role of Harderian gland-derived growth factor (HGDGF), the effects of HGDGF and various other growth factors on the growth of cultured guinea pig cornea stromal cells were examined. HGDGF increased the incorporation of [3H]thymidine to 150% of the control (5% fetal calf serum). The combination of HGDGF with fibroblast growth factors (FGFs) or platelet-derived growth factor enhanced the cell growth over that of either growth factor alone, increasing the incorporation of [3H]thymidine to 180 and 190% of the control, respectively. The combination of HGDGF with transforming growth factor (TGF-beta) decreased the growth to 60% of the control, and epidermal growth factor had no effect on the activity of HGDGF. The growth-stimulating activity of HGDGF was inhibited by suramin in a different manner from that of FGFs. These findings suggest that HGDGF binds a specific cell-surface receptor and plays a role in the repair of injured parts of the cornea and in the maintenance of the cornea stromal cells.

Animals↗