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Biomedical subjects

K Kasai

Publications and source records attributed to K Kasai.

At least 199 records · Page 11Linked to original sources
PubMed1995

Prior enrichment of human immunodeficiency virus DNA with probe DNA particles for efficient PCR diagnosis.

We report here a novel method by which one can recover human immunodeficiency virus (HIV) DNA in a small volume (approximately 50 microliters) of solution from 8 ml of crude cell lysate which contains as few as several HIV DNA copies. The method uses the specific binding of HIV DNA to HIV probe DNA particles. The HIV DNA thus concentrated on the particles can be subjected to the PCR assay. The method also enables the examination of 100 individual blood specimens in a combined form.

Base Sequence↗
PubMed1995

Regulation of inducible nitric oxide production by cytokines in human thyrocytes in culture.

We now report on the induction and modulation of NO production by cytokines in primary cultures of human thyrocytes and the effect of NO on iodine organification by human open thyroid follicles in the process of thyroid hormone biosynthesis. Although unstimulated thyrocytes produced little NO (measured as nitrite), interleukin-1 alpha or beta (IL-1 alpha/beta) substantially increased NO formation. Interferon-gamma (IFN-gamma) by itself failed to stimulate NO formation but markedly increased the IL-1-stimulated NO production. Tumor necrosis factor-alpha alone did not induce NO production but did so slightly in the presence of IFN-gamma. Induction of NO formation by thyrocytes upon stimulation with IL-1 alpha + IFN-gamma was accompanied by the synthesis of tetrahydrobiopterin (BH4), an obligatory cofactor of NOS. Coinduction of NO and BH4 synthesis in thyrocytes was preceded by coexpression of messenger RNAs for NOS and GTP cyclohydrolase I (GTPCH), the rate-limiting enzyme for de novo synthesis of BH4. NO synthesis was prevented by an inhibitor of GTPCH, 2,4-diamino-6-hydroxypyrimidine, and this inhibition was completely reversed by administration of sepiapterin, a substrate for BH4 synthesis via pterin salvage pathway. In contrast to IFN-gamma, some cytokines such as interferon-alpha, IL-4, and transforming growth factor-beta 1 inhibited the IL-1-induced NO production. Finally, a possible role of NO on thyroid hormone synthesis was investigated. Iodine organification by human open thyroid follicles was inhibited by two kinds of NO donor but not by cell permeable cyclicGMP analog. Thus, cytokines such as IL-1, IL-1/IFN-gamma, and tumor necrosis factor-alpha/IFN-gamma stimulate human thyrocytes to produce NO; this process can be modulated by other cytokines and coregulated with a cofactor BH4 biosynthesis, and resulting NO may affect cell function including thyroid hormone synthesis.

Amino Acid Oxidoreductases↗
PubMed1995

[Treatment of secondary hyperparathyroidisms of predialysis chronic renal failure with low doses of 1.25(OH)2D3].

Although disorders of renal calcitriol synthesis play an important role in the pathogenesis of secondary hyperparathyroidism in the early and moderate phase of chronic renal failure, the treatment of secondary hyperparathyroidism with vitamin D metabolite has not attained consensus from the view point that is accelerates the progression of renal disease. The aim of this study was to evaluate the efficacy and adverse effect of low-dose daily oral treatment of 1.25 vitamin D for patients with mild to moderate renal failure. Fifteen chronic renal failure patients with serum creatinine ranging from 2.5 to 6.1 mg/dl and serum intact parathyroid hormone ranging from 100 to 450 pg/ml, were treated with oral 0.25-0.5 micrograms of 1.25 vitamin D for six months, after a six month control periods. In the six months control periods, serum intact parathyroid hormone, alkaline phosphatase activity, and bone gla protein increased significantly, however after the treatment of 1.25 vitamin D, serum intact parathyroid hormone, alkaline phosphatase activity, and bone gla protein decreased significantly. Serum calcium concentration increased significantly after the initiation of 1.25 vitamin D treatment, so it could not be ascertained whether or not 1.25 vitamin D directly suppressed parathyroid hormone synthesis. Bone mineral densities did not change within one year. Renal function was evaluated from the slopes of the reciprocal serum creatinine concentration versus time. The slopes did not change after the administration of 1.25 vitamin D. In conclusion, 1.25 vitamin D treatment of secondary hyperparathyroidism in patients with mild to moderate renal failure had beneficial therapeutic effect on humoral bone parameters, and did not show any adverse effect on renal function.

Aged↗
PubMed1995

Pentamethyl-hydroxychromane, vitamin E derivative, inhibits induction of nitric oxide synthase by bacterial lipopolysaccharide.

Vitamin E, a lipophilic antioxidant, has effectively inhibited the activation of cytokine-induced nuclear factor kB (NFkB). Since NFkB plays a critical role in the induction of an isoform of nitric oxide synthase (iNOS) gene by lipopolysaccharide (LPS), we investigated the effect of a vitamin E derivative, pentamethyl-hydroxychromane (PMC), which is an extremely potent inhibitor of NFkB activation, on the induction of nitric oxide (NO) synthesis and iNOS mRNA by LPS. PMC inhibited the LPS-stimulated induction of NO production in a concentration-dependent fashion in cultured J774 macrophages and rat vascular smooth muscle cells without evidence of cytotoxicity. However, the addition of PMC to J774 macrophages after the induction of iNOS did not inhibit NO production. Treatment of J774 macrophages with LPS resulted in a significant expression of iNOS mRNA, which was profoundly reduced by PMC. Data suggest that PMC inhibits the induction of iNOS by preventing iNOS gene expression through inhibition of NFkB activation.

Amino Acid Oxidoreductases↗
PubMed1995

Vesnarinone inhibits induction of nitric oxide synthase in J774 macrophages and rat cardiac myocytes in culture.

OBJECTIVE: We investigated whether vesnarinone alters the induction of nitric oxide (NO) synthesis by bacterial lipopolysaccharide (LPS) or in combination with interferon-gamma in cultured J774 macrophages and rat cardiac myocytes. METHODS: The induction of NO synthesis was determined by measuring the stable end-product nitrite. The cytotoxic effect of vesnarinone was assessed by measuring cell respiration. Any change in mRNA levels for NO synthase (NOS) was determined by RT-PCR. RESULTS: Stimulation by LPS or in combination with interferon-gamma increased the accumulation of nitrite in the supernatant of J774 macrophages or cardiac myocytes. NOS induction accounted for this accumulation of nitrite, as dexamethasone, NG-methyl-L-arginine, and cycloheximide each reduced the production of nitrite in both types of cells. Vesnarinone produced a significant decline in the cumulative production of nitrite in both types of cells without evidence of cytotoxicity. However, the addition of vesnarinone after induction of NOS did not inhibit nitrite production. Treatment with LPS or in combination with interferon-gamma led to a significant expression of NOS mRNA in both types of cells that was significantly reduced by vesnarinone. CONCLUSIONS: Vesnarinone inhibited NO synthesis by inhibiting the induction of NOS in J774 macrophages and cardiac myocytes. This drug may exert a beneficial effect in patients with heart failure, in part, by attenuating the production of NO.

Animals↗
PubMed1994

Deficiency in fertilization by morphologically abnormal sperm produced by azh mutant mice.

Male mice homozygous for the azh mutation produce spermatozoa with abnormal head shapes and have significantly reduced fecundity, to between 5% and 10% that of wild-type or heterozygous mice. Several possible causes of this infertility were investigated. No gross endocrine disorders in azh/azh male mice were observed, and they exhibited apparently normal mating behavior. In addition, their sperm were motile, were capable of hyperactivated motility, and did not show premature acrosome reactions. However, quantitative analysis revealed slight but significant reductions in several motility parameters. Analysis of embryos following mating of azh/azh males with superovulated females indicated a reduction in the number of fertilized eggs compared to control matings. In vitro, spermatozoa from azh/azh mice failed to fertilize cumulus-intact/zona-intact and cumulus-free/zona-intact ova, although they successfully fertilized zona-free ova. These results indicate that the primary defect in fertility of azh/azh male mice is a result of sperm quality, likely, in sperm morphology, and is manifest at the level of interaction with the zona pellucida.

Animals↗
PubMed1994

Incidence of latent infection of Epstein-Barr virus in lung cancers--an analysis of EBER1 expression in lung cancers by in situ hybridization.

To evaluate the presence of Epstein-Barr virus (EBV) in lung cancers of Japanese patients, 81 lung cancers were examined using a highly sensitive in situ hybridization (ISH) method, employing an antisense oligonucleotide probe for EBV-encoded small nuclear RNA-1 (EBER). EBER1 expression was demonstrated in one poorly differentiated squamous cell carcinoma associated with marked lymphoid stroma (PDSCC-LS), two well differentiated adenocarcinomas, and two moderately differentiated squamous cell carcinomas, but was not detectable in other lung cancers, including small cell carcinomas. Unlike lymphoepithelioma-like undifferentiated carcinoma (LELC) of the lung, the PDSCC-LS consisted of poorly differentiated cells with distinct cell borders and nuclei with a coarse chromatin pattern and some prominent nucleoli. Most of the cancer cells expressed intense EBER1 signals. Although small to moderate numbers of cells positive for EBER1 were present in two adenocarcinomas and two squamous cell carcinomas, EBER1 signals varied in intensity and number in these four cases. Although polymerase chain reaction (PCR) and Southern blot hybridization with a 32P-labelled probe internal to the primers were conducted to detect the EBV genome in 24 lung cancers, including five EBER1-positive cases, the genome was found to be positive in the five cases with EBER1-positive staining, including the PDSCC-LS, two adenocarcinomas and two squamous cell carcinomas, but not in the other cases. This study indicates that the morphological features of EBV-associated lung cancers are not restricted to the typical LELC type.

Adenocarcinoma↗
PubMed1994

Immunohistochemical localization of a beta-D-galactoside-binding lectin at the human maternofetal interface.

The 14 kD S-type lectin from human placenta may have a role in regulating the maternal immune response to fetal antigens. In this study, an immunoperoxidase technique was used to determine the distribution of the lectin at the human maternofetal interface. Tissue obtained during the first trimester of pregnancy and at term was used. The lectin was not detectable in either the villous syncytiotrophoblast or the underlying cytotrophoblast in first-trimester tissue, although some cells of the cytotrophoblast columns were reactive. It was also not detectable in villous or extravillous trophoblast populations at term. In contrast, strong reactivity was found in decidual stromal cells throughout gestation, and endometrial stromal cells were also positive. The lectin is, therefore, not a component of the immunosuppressive factors associated with syncytiotrophoblast membranes, but may have a role in either the decidual control of trophoblast migration or some functions unrelated to pregnancy, or both.

Chorionic Villi↗
PubMed1994

The immunocytochemical localization of tumour necrosis factor and leukotriene in the rat heart and lung during endotoxin shock.

After the intravenous administration of lipopolysaccharide at a dose of 3.0 mg/100 g to rats, immunoreactive sites for tumour necrosis factor (TNF) and peptide leukotrienes (LTs) were examined in the heart and lung. Immunoreaction for TNF is preferentially localized on the apical endothelial cell surface of the vessels and in lysosomes of inflammatory and interstitial cells. Lysosomes of cardiac muscle cells which undergo degeneration are also reactive. Peptide LTs in inflammatory cells give almost the same reactions as those for TNF. However, the production of peptide LTs occurs uniquely in cardiac muscle cells in the media of the pulmonary vein, although lysosomes of intracardiac muscle cells which undergo degeneration do not show immunoreactivity. These results suggest that the degeneration of cardiac muscle cells may be induced not only by endogenous TNF but also by peptide LTs which are produced in muscle cells of the venous media and are transported to the myocardium via the coronary circulation.

Animals↗
PubMed1994

Further evidence by site-directed mutagenesis that conserved hydrophilic residues form a carbohydrate-binding site of human galectin-1.

To identify critical amino acid residues for carbohydrate binding of galectins (soluble beta-galactoside-binding lectins found in the animal kingdom). site-directed mutagenesis was performed on human galectin-1. On the basis of the previous results (Hirabayashi and Kasai (1992) J Biol Chem 266:23648-53), more systematic mutagenesis experiments were performed in order to confirm the concept that conserved hydrophilic residues play a central role. When a homologous substitution was made for highly conserved His44, Arg48 or Asn61, the resultant mutant (H44Q, R48H or N61D, respectively) almost completely lacked carbohydrate-binding ability, as found previously for Asn46, Glu71 and Arg73 mutants. This suggests these six hydrophilic residues are essential. On the other hand, when less conserved Lys63, Arg111 or Asp125 were substituted, the resultant mutant (K63H, R111H or D125E, respectively) retained almost the same affinities to asialofetuin and lactose as the wild-type galectin. Therefore, none of these residues is directly involved in the binding. These results, together with the previous observation that the above six essential residues are all encoded in the largest exon of the gene and are located close to each other in the central, most hydrophilic region of the protein, suggest that the residues form a carbohydrate-binding site of galectin.

Amino Acid Sequence↗
PubMed1994

Expression of P0 protein in sural nerve of a patient with hereditary motor and sensory neuropathy type III.

We present expression of Po protein and Po mRNA on the sural nerve of a patient with hereditary motor and sensory neuropathy type III. This patient was identified with a point mutation in Po gene, which resulted in the substitution of glycine for arginine in transmembrane domain of P0 protein. An electron microscopic examination revealed very thin myelinated fibers surrounded by multilamellated onion bulbs composed with greatly proliferated Schwann cells. An immunocytochemical and immunoblot analysis is showed P0 protein normally expressed in myelin on the sural nerve. By in situ hybridization, mRNA of P0 protein was detected at normal levels in Schwann cell cytoplasm. Those observations indicated that there was no truncated myelin P0 protein in peripheral nerve of this patient.

Adolescent↗
PubMed1994

Anti-shock effect of pituitary adenylate cyclase activating polypeptide (PACAP) on experimental endotoxin shock in dogs.

Effects of pituitary adenylate cyclase activating polypeptide with 38 amino acid residues (PACAP-38) on both cardiovascular functions and plasma hormone levels during endotoxin shock were studied in anesthetized dogs. When PACAP-38 (a bolus 420 pmol/kg injection or a bolus 420 pmol/kg injection followed by a continuous 30 pmol/kg/min infusion for 60 min) was administered intravenously 5 min after application of endotoxin, both mean arterial pressure and cardiac output were restored at 10 min. The continuous administration of PACAP-38 was more effective in improving the symptoms of shock. Plasma adrenalin and cortisol levels were significantly increased by both regimens. These results clearly indicate that the anti-shock properties of PACAP-38 may be attributed to its abilities to increase plasma cortisol and adrenalin levels and to stimulate cardiac function.

Animals↗
PubMed1994

Glycogenolytic activity of pituitary adenylate cyclase activating polypeptide (PACAP) in vivo and in vitro.

When pituitary adenylate cyclase activating polypeptide (PACAP-38, 420 pmol/kg) was injected to anesthetized dogs, hyperglycemia associated with elevation in plasma glucagon and adrenalin levels was observed. In dogs undergone adrenalectomy, the same dose of it stimulated insulin, but not glucagon, release and hyperglycemia was not observed. Much higher dose was needed to evoke hyperglycemia in such dogs. Next, direct glycogenolytic activities of PACAP, glucagon and adrenalin were studied on cultured rat hepatocytes. PACAP38 stimulated glucose output via cAMP production by the cells, but the potency was far less than that of glucagon. Adrenalin, however, could not exert the activity with physiological concentrations. These results indicate that hyperglycemic effect of PACAP can be attributed mainly to indirect effects resulting from glucagon and adrenalin release and possibly in part to a direct action on hepatocytes.

Adrenalectomy↗