Biomedical subjects

S Asahi

Publications and source records attributed to S Asahi.

At least 19 recordsLinked to original sources

PubMed2002

Video-assisted parathyroidectomy.

A parathyroid tumor is not larger than other tumors, so minimally invasive surgery has long been a major focus of parathyroid surgeons. Improving endoscopic instruments has facilitated the recent changes in approaches to parathyroid surgery. Endoscopic parathyroidectomy is developed in a totally closed space with CO2 gas insufflation. This method has a risk of complications, such as extensive emphysema or hypercarbia. Minimally invasive video-assisted parathyroidectomy (MIVAP) has greater safety, low cost, easy procedure and flexibility in changing the working space including conversion to open method when compared with endoscopic parathyroidectomy. MIVAP can be performed with only a 1-1.5-cm small incision on the neck. MIVAP is indicated in the patient with parathyroid adenoma or renal hyperplasia that is defined preoperatively using ultrasonography and 99mTc-methoxyisobutylisonitrile (MIBI) scan. Furthermore, the radio-guided technique using nuclear navigation after preoperative administered MIBI is being developed. This method is so useful during MIVAP that we combined MIVAP and radio-guided surgery to develop minimally invasive radio-guided and video-assisted parathyroidectomy (MIRVAP). After injection of 600 MBq of MIBI, intraoperative nuclear mapping was performed using a hand-held gamma probe. Then we expected to find swollen parathyroid tumor at surgery when radioactivity at a level relatively higher than background was found. Following this mapping result, MIVAP was started and succeeded. The radio-guided technique is also indicated for open parathyroidectomy (radio-guided open parathyroidectomy, RGOP) in multiglandular disease (MGD) when it was not possible to identify those lesions completely, for instance in asymmetric hyperplasia, such as multiple endocrine neoplasia (MEN) 1. In conclusion, MIVAP is beneficial for minimal invasiveness and cosmesis. Furthermore, radio-guided parathyroidectomy (MIRVAP and RGOP) is more useful and feasible. Improvement of endoscopic instruments and modification of the dose of MIBI administered might facilitate treating more cases by MIRVAP instead of RGOP.

Animals↗

PubMed2001

Requirement of intact disulfide bonds in orexin-A-induced stimulation of gastric acid secretion that is mediated by OX1 receptor activation.

Orexin-A is a neuropeptide consisting of 33 amino acids with two intrachain disulfide bonds, namely Cys6-Cys12 and Cys7-Cys14, and is a potent stimulator of food consumption and gastric acid secretion. In contrast, orexin-B, a peptide containing 28 amino acids without disulfide bond, which has no stimulatory action of gastric acid. The objective of the present study was to characterize the receptor-mediated mechanism of orexin-A-induced stimulation of gastric acid secretion using orexin-A-related peptides with modification of disulfide bonds. Intracisternal injection of orexin-A, but not orexin-B or orexin-A (15-33), that does not contain both disulfide bonds stimulated gastric acid secretion in pylorus-ligated conscious rats. The ability of the stimulation of gastric acid output was less in three alanine-substituted orexin-A, [Ala(6,12)]orexin-A, [Ala(7,14)]orexin-A, and [Ala(6,7,12,14)]orexin-A, than orexin-A. Orexins-induced calcium increase was measured in CHO-K1 cells expressing OX1R or OX2R. Orexin-A induced a transient increase in [Ca(2+)]i in CHO-K1/OX1R cells in a dose-dependent manner. EC50 values for OX1R of orexin-A, orexin-B, or orexin-A (15-33) was 0.068, 0.69 or 4.1 nM, respectively, suggesting that peptides containing no disulfide bonds have lower potency for the receptor. Agonistic activity for OX1R of the three orexin-A analogues with modification of one or both disulfide bonds was significantly reduced as compared with that of orexin-A. EC50 values for OX2R of orexin-A and orexin-B was almost equal but potency for the receptor of orexin-A (15-33) and three alanine substituted orexin-A was less than that of orexin-A. A significant inverse relationship between gastric acid output and EC50 values for OX1R, but not OX2R, was observed. These results suggested that the orexin-A-induced acid stimulation requires OX1R activation and that disulfide bonds in orexin-A may have a key role in the receptor activation.

Amino Acid Sequence↗

PubMed2001

Establishment of a human hepatocyte line (OUMS-29) having CYP 1A1 and 1A2 activities from fetal liver tissue by transfection of SV40 LT.

Immortalized human hepatocytes that can retain functions of drug-metabolizing enzymes would be useful for medical and pharmacological studies and for constructing an artificial liver. The aim of this study was to establish immortalized human hepatocyte lines having differentiated liver-specific functions. pSVneo deoxyribonucleic acid, which contains large and small T genes in the early region of simian virus 40, was introduced into hepatocytes that had been obtained from the liver of a 21-wk-old fetus. Neomycin-resistant immortalized colonies were cloned and expanded to mass cultures to examine hepatic functions. Cells were cultured in a chemically defined serum-free medium, ASF104, which contains no peptides other than recombinant human transferrin and insulin. As a result, an immortal human hepatocyte cell line (OUMS-29) having liver-specific functions was established from one of the 13 clones. Expression of CYP 1A1 and 1A2 messenger ribonucleic acid by the cells was induced by treatment with benz[a]pyrene, 3-methylcholanthrene, and benz[a]anthracene. OUMS-29 cells had both the polycyclic aromatic hydrocarbon receptor (AhR) and AhR nuclear translocator. Consequently 7-ethoxyresorufin deethylase activity of the cells was induced time- and dose-dependently by these polycyclic aromatic hydrocarbons. This cell line is expected to be instrumental as an alternative method in animal experiments for studying hepatocarcinogenesis, drug metabolisms of liver cells, and hepatic toxicology.

Cell Line↗

PubMed2001

Establishment of the transformants expressing human cytochrome P450 subtypes in HepG2, and their applications on drug metabolism and toxicology.

Transformants with stable expression of a series of human cytochrome P450 (CYP) subtypes in the human hepatic cell line, HepG2, were established. These transformants are designated Hepc/1A1.4, Hepc/1A2.9, Hepc/2A6L.14, Hepc/2B6.68, Hepc/2C8.46, Hepc/2C9.1, Hepc/2C19.12, Hepc/2D6.39, Hepc/2E1.3-8 and Hepc/3A4.2-30, which stably expressed human CYP1A1, CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1 and CYP3A4, respectively. The expression of the CYP subtypes in the transformants was confirmed by both determination of enzyme activities and the reverse transcriptase polymerase chain reaction (RT-PCR) procedure. The apparent K(m) values of the expressed CYP subtypes for their specific substrates were close to those of human liver microsomes. In addition to their CYP activities, these transformants retained glucuronide- and sulfate-conjugating activities. Furthermore, the activities of CYP2C9, CYP2D6 and CYP3A4 were inhibited by their specific inhibitors. The cytotoxicity of acetaminophen (APAP), cyclophosphamide (CPA) and benz[a]anthracene (BA) were analyzed by CYP-expressing transformants. The cytotoxicity depended on the expression of CYP subtypes and increased in a dose-dependent manner. These results show the metabolic activation of APAP, CPA and BA by the specific CYP subtypes expressed in the transformants and demonstrate the usefulness of these transformants for in vitro metabolic and toxicological studies in human liver.

Acetaminophen↗

PubMed2000

Pre- and postoperative bone metabolism of primary hyperparathyroidism.

UNLABELLED: Primary hyperparathyroidism (PHPT) is a well-known indicator of severe bone loss. However, the recovery process of bone mineral density after surgery in PHPT patients is not sufficiently clear. We examined postoperative bone metabolism in 24 PHPT patients. PATIENTS AND METHODS: Subjects were 24 patients with PHPT upon whom we performed parathyroidectomy in the Department of Surgery II, Fukushima Medical University. Mean age was 54.2 years and the male-to-female ratio was 10:14; mean time of follow-up was 27.3 months. Patients were divided histopathologically into 16 adenomas and eight hyperplasias, and classified by heredity into seven familial (six, MEN 1; one, MEN 2) and 17 sporadic types. Bone mineral density was measured by dual energy X-ray absorptometry (DXA) and digital image processing (DIP). Age-matched values of these parameters were obtained. Serum bone metabolic parameters; ionized calcium (CaF), phosphorus, intact PTH (iPTH), c-PTH, ALP, osteocalcin (OC) and PTHrP were measured. RESULTS: PHPT patient preoperative bone mineral densities were significantly lower than those of healthy controls. Those by DIP method were lower than those by DXA. High CaF, iPTH, OC and ALP levels were indicated before surgery, but all parameters immediately became normal. Longitudinal bone mineral density changes of asymptomatic cases increased more than those of patients with renal stone and/or ostitis fibrosa. In adenoma cases, tumor weights were significantly inversely, which correlated with preoperative DIP bone density measurements. CONCLUSION: Preoperative PHPT patients showed decreased bone density; bone loss in symptomatic cases was especially prominent compared to asymptomatic cases. Most PHPT patients had not completed the BMD recovery after surgery, so even asymptomatic and mild PHPT patients should undergo parathyroidectomy to minimize irreversible bone loss.

Absorptiometry, Photon↗

PubMed2000

Retrospective study of porcine circovirus 2 infection in Japan: seven cases in 1989.

Retrospectively, we demonstrated that seven pigs necropsied in 1989 had characteristic porcine circovirus 2 (PCV-2) lymphoid tissue lesions of severe lymphoid depletion, syncytial giant cell formation, and intracytoplasmic inclusion bodies in macrophages. Immunohistochemically, PCV-2 antigen was detected in these tissues and the distribution of positive staining corresponded to the distribution of inclusion bodies. Electron microscopy demonstrated viral particles compatible with porcine PCV-2. Therefore, the disease occurred in Japan as early as 1989.

Animals↗

PubMed2000

Formation of a dihydroxy metabolite of phenytoin in human liver microsomes/cytosol: roles of cytochromes P450 2C9, 2C19, and 3A4.

Formation of four oxidative metabolites from the anticonvulsant drug phenytoin (DPH) catalyzed by human liver microsomal cytochrome P450 (P450) enzymes was determined simultaneously. Under the conditions in which linearity for formation of 4'-hydroxylated DPH (4'-HPPH; main metabolite) was observed, human liver cytosol increased microsome-mediated DPH oxidation. 3',4'-Dihydroxylated product (3', 4'-diHPPH) formation was 10 to 40% of total DPH oxidation in the presence of liver cytosol. 3'-Hydroxy DPH formation was catalyzed by only one of the human liver microsomal samples examined and 3', 4'-dihydrodiol formation could not be detected in all samples. In the presence of liver cytosol, 3',4'-diHPPH formation activity from 100 microM 4'-HPPH was correlated with testosterone 6beta-hydroxylation activity and CYP3A4 content. However, 3', 4'-diHPPH formation using 1 or 10 microM 4'-HPPH as a substrate was not correlated with contents of any P450s or marker activities. Of 10 cDNA-expressed human P450 enzymes examined, CYP2C19, CYP2C9, and CYP3A4 catalyzed 3',4'-diHPPH formation from the primary hydroxylated metabolites (3'-hydroxy-DPH and 4'-HPPH). Fluvoxamine and anti-CYP2C antibody inhibited 3',4'-diHPPH formation from 10 microM 4'-HPPH in a human liver sample that contained relatively high levels of CYP2C, whereas ketoconazole and anti-CYP3A antibody showed inhibitory effects on the activities in liver microsomal samples in which CYP3A4 levels were relatively high. These results suggest that CYP2C9, CYP2C19, and CYP3A4 all have catalytic activities in 3',4'-diHPPH formation from primary hydroxylated metabolites in human liver and that the hepatic contents of these three P450 forms determine which P450 enzymes play major roles of DPH oxidation in individual humans.

Catalysis↗

PubMed1999

Bcl-2 protein expression and gut neurohormonal polypeptide/amine production in colorectal carcinomas and tumor-neighboring mucosa, which closely correlate to the occurrence of tumor.

To clarify whether advanced colorectal carcinomas and tumor-neighboring mucosa simultaneously produce both Bcl-2 protein and gut neurohormonal polypeptides and/or amines, and the interrelationship of these phenomenon, we studied retrospective analysis of Bcl-2 protein production and neuroendocrine characteristics in 52 cases of advanced colorectal carcinoma and surrounding mucosa. All of the tumor-neighboring mucosa presented hyperplasia. The rates of enhanced immunoreactivity of the tumor-neighboring mucosa and of positive immunoreactivity of the carcinomas against human Bcl-2 protein and against human vasoactive intestinal polypeptide, pancreatic polypeptide and somatostatin were 78.8% and 94.2%, 82.7% and 59.6%, 78.8% and 67.3%, and 88.5% and 84.6% respectively. Double immunostaining for Bcl-2 protein and each peptide hormone revealed simultaneous expression. In contrast, that of tumor-neighboring mucosa and carcinomas to serotonin and chromogranin-A and to argyrophilia were 11.5% and 1.9%, 32.7% and 17.3%, and 26.9% and 21.2%, respectively. We concluded that tumor-neighboring crypt cells displayed not only hyperplasia but also neuroendocrine characteristics and that enhanced Bcl-2 protein immunoreactivity correlated with tumor occurrence in the wall of the colorectum. The production of Bcl-2 protein by tumor cells and tumor-neighboring crypt cells indicates that the bcl-2 protooncogene may act not only as an inhibitor of apoptosis but also as an inducer of neuroendocrine differentiation from the latent characteristics of the endodermal stem cell.

Adult↗

PubMed1999

Enhancement of cytochrome P-450 3A4 catalytic activities by cytochrome b(5) in bacterial membranes.

Activities of testosterone, nifedipine, and midazolam oxidation by recombinant cytochrome P-450 (P-450) 3A4 coexpressed with human NADPH-P-450 reductase (NPR) in bacterial membranes (CYP3A4/NPR membranes) were determined in comparison with those of other recombinant systems and of human liver microsomes with high contents of CYP3A4. Growth conditions for Escherichia coli transformed with the bicistronic construct affected expression levels of CYP3A4 and NPR; an excess of NPR over P-450 in membrane preparations enhanced CYP3A4-dependent testosterone 6beta-hydroxylation activities of the CYP3A4/NPR membranes. Cytochrome b(5) (b(5)) and apolipoprotein b(5) further enhanced the testosterone 6beta-hydroxylation activities of CYP3A4/NPR membranes after addition to either bacterial membranes or purified enzymes. NPR was observed to enhance catalytic activity when added to the CYP3A4/NPR membranes, either in the form of bacterial membranes or as purified NPR (in combination with cholate and b(5)). Apparent maximal activities of testosterone 6beta-hydroxylation in CYP3A4/NPR membranes were obtained when the molar ratio of CYP3A4/NPR/b(5) was adjusted to 1:2:1 by mixing membranes containing each protein. Testosterone 6beta-hydroxylation, nifedipine oxidation, and midazolam 4- and 1'-hydroxylation activities in CYP3A4/NPR membranes plus b(5) systems were similar to those measured with microsomes of insect cells coexpressing CYP3A4 with NPR and/or of human liver microsomes, based on equivalent CYP3A4 contents. These results suggest that CYP3A4/NPR membrane systems containing b(5) are very useful models for prediction of the rates for liver microsomal CYP3A4-dependent drug oxidations.

Anesthetics, Intravenous↗

PubMed1997

Biosynthesis of archaeosine, a novel derivative of 7-deazaguanosine specific to archaeal tRNA, proceeds via a pathway involving base replacement on the tRNA polynucleotide chain.

Archaeosine is a novel derivative of 7-deazaguanosine found in transfer RNAs of most organisms exclusively in the archaeal phylogenetic lineage and is present in the D-loop at position 15. We show that this modification is formed by a posttranscriptional base replacement reaction, catalyzed by a new tRNA-guanine transglycosylase (TGT), which has been isolated from Haloferax volcanii and purified nearly to homogeneity. The molecular weight of the enzyme was estimated to be 78 kDa by SDS-gel electrophoresis. The enzyme can insert free 7-cyano-7-deazaguanine (preQ0 base) in vitro at position 15 of an H. volcanii tRNA T7 transcript, replacing the guanine originally located at that position without breakage of the phosphodiester backbone. Since archaeosine base and 7-aminomethyl-7-deazaguanine (preQ1 base) were not incorporated into tRNA by this enzyme, preQ0 base appears to be the actual substrate for the TGT of H. volcanii, a conclusion supported by characterization of preQ0 base in an acid-soluble extract of H. volcanii cells. Thus, this novel TGT in H. volcanii is a key enzyme for the biosynthetic pathway leading to archaeosine in archaeal tRNAs.

Amino Acid Sequence↗

PubMed1997

Impaired left ventricular diastolic filling occurs in diabetic patients without atherosclerotic coronary artery disease.

Using left ventriculography, left ventricular diastolic function was studied in 24 diabetic patients who had angina pectoris without atherosclerotic large-vessel coronary artery diseases (group A, 14 patients with exercise-induced ischemic ST-T changes as seen during electrocardiogram; group B, 10 patients without such changes). In groups A and B, the global peak filling rate was significantly less than that in control patients without diabetes or cardiac diseases. The ratio of the global time to the peak filling rate to the diastolic time was higher in both groups A and B than in the control groups. However, the total of time differences, defined as the sum of the time differences between global time to the peak filling rate and each of the three regional time to the peak filling rate, was greater in group A than in either group B or the control patients. Total time difference was similar in group B and the controls. Left ventricular diastolic filling was impaired in diabetic patients without large-vessel coronary artery disease. Impaired diastolic filling was present regionally in patients with ischemic ST-T change but globally in those without such change.

Adult↗

PubMed1997

Higher prevalence of Borna disease virus infection in blood donors living near thoroughbred horse farms.

It is believed that Borna disease virus (BDV), an etiological agent of progressive polioencephalomyelitis in horses and sheep, is closely associated with psychiatric disorders in humans since the prevalence of BDV is higher in psychiatric patients than in blood donors. We investigated whether or not BDVs in humans are derived from infected domestic animals, by characterizing the BDVs in blood donors and horses derived from the same region of Hokkaido island, Japan. The seroprevalences (2.6 to 14.8%) of BDV were significantly higher in the blood donors from four regions where most horse farms are concentrated, compared with only 1% in the blood donors from Sapporo, the largest city in Hokkaido.BDV RNA was also detected in peripheral blood mononuclear cells from most of the seropositive horses and blood donors by nested reverse transcriptase-polymerase chain reaction. These findings support that BDV may be horizontally transmitted, at least in part, from infected horses to humans.

Animals↗

PubMed1996

Demonstration of Borna disease virus RNA in peripheral blood mononuclear cells derived from Japanese patients with chronic fatigue syndrome.

CFS, a recently named heterogeneous disorder, is an illness of unknown etiology. The association of CFS with viral infections has been suggested. A common association between CFS and several viruses examined has not been confirmed. Here, we centered on the possible link between CFS and BDV infection. By nested RT-PCR followed by hybridization, BDV RNA was demonstrated as a clear signal in PBMCs in 3 out of 25 CFS patients. The amplified cDNA fragments were cloned and sequenced. A total of 16 clones were studied. Intra-patients divergencies of the p24 were 2-9%, 3-20%, and 3-11% in the deduced amino acids. Inter-patient divergencies among the 16 clones were 3-24%. Antibodies to recombinant BDV p24 protein were detected in 6 CFS patients including one carrying BDV RNA. Overall, these gave the prevalence of 32% (8/25) in Japanese CFS patients, suggesting that Japanese CFS is highly associated with active infection of BDV, or a related agent.

Adult↗

PubMed1996

Borna disease virus RNA in peripheral blood mononuclear cells obtained from healthy dairy cattle.

We examined natural infection of Borna disease virus (BDV) in 74 healthy dairy cattle in Japan. The seroprevalence determined using recombinant BDV p24 protein was 20.3%. The prevalence of BDV RNA in peripheral blood mononuclear cells (PBMCs) determined by polymerase chain reaction for p24 was 10.8%. Cell fraction of the PBMCs revealed the presence of BDV RNA in the T cell-enriched fraction. Thus, BDV infection is widespread even among healthy cattle.

Animals↗

PubMed1996

Possible correlation between Borna disease virus infection and Japanese patients with chronic fatigue syndrome.

Borna disease virus (BDV) is a neurotropic, as yet unclassified, non-segmented, negative-sense, single-strand RNA virus. Natural infection with this virus has been reported to occur in horses and sheep. In addition, antibodies to BDV in plasma or BDV RNA in peripheral blood mononuclear cells (PBMCs) were also found in patients with neuropsychiatric diseases. We describe here the possible link between the patients with chronic fatigue syndrome (CFS) and infection with BDV.

Adult↗

PubMed1996

Demonstration of borna disease virus RNA in peripheral blood mononuclear cells derived from domestic cats in Japan.

Borna disease virus (BDV) naturally infects horses, sheep, and several other species, including humans, and it is believed to be related to neurological disorders. BDV infection in domestic cats has also been demonstrated by serological assays. We demonstrated for the first time BDV RNA in peripheral blood mononuclear cells from 11 of 83 (13.3%) randomly selected domestic cats in Japan by nested reverse transcriptase-PCR. The BDVs from cats were similar to but slightly different from those from horses and humans, as shown by sequencing the reverse transcriptase-PCR products. None of the cats was positive for both BDV RNA and anti-BDV antibodies.

Amino Acid Sequence↗

PubMed1996

Potent neuropeptide Y Y1 receptor antagonist, 1229U91: blockade of neuropeptide Y-induced and physiological food intake.

Neuropeptide Y (NPY) is thought to increase food intake through the action of Y1 (-like) receptors in the hypothalamus. To confirm the involvement of Y1 receptors in feeding behavior, selective and potent antagonists for Y1 receptors are required. In the present study, we showed that a peptide, 1229U91 [(Ile,Glu,Pro,Dpr,Tyr,Arg,Leu,Arg, Tyr-NH2)2 cyclic (2,4'),(2',4)-diamide], is a potent and selective antagonist for Y1 receptors. 1229U91 displaced [125I]peptide YY (PYY) binding to membranes of human neuroblastoma-derived SK-N-MC cells that predominantly express Y1 receptors with a K1 value 0.10 nM and inhibited the NPY-induced increase in intracellular calcium levels(IC50 = 0.27 nM). In contrast, the K1 values for [125I]PYY binding to Y2 receptors in membranes of human neuroblastoma-derived SK-N-BE2 cells and rat hypothalamus were 700 nM and more than 1 microM, respectively. Although [125I]PYY could not detect Y1 receptors in the rat hypothalamic membranes, [125I]1229U91 revealed binding sites with a high affinity (Kd = 18 pM), indicating the presence of Y1 receptors in the hypothalamus. Intracerebroventricular injection of 1229U91 (30 micrograms) into male Sprague-Dawley rats completely inhibited NPY (5 micrograms)-induced food intake without any other behavioral change. Furthermore, intracerebroventricular injection of 1229U91 significantly suppressed physiological feeding behavior after overnight fasting. These results indicate that Y1 receptors in the rat hypothalamus mediate NPY-induced food intake, and that physiological feeding behavior after overnight fasting may be largely regulated by NPY via Y1 receptors. 1229U91 may be useful for further elucidating the pathophysiological roles of NPY in feeding behavior.

Animals↗

PubMed1996

Detection of turkey rhinotracheitis virus from chickens with swollen head syndrome by reverse transcriptase-polymerase chain reaction (RT-PCR).

We developed a sensitive and specific method, reverse transcriptase-polymerase chain reaction (RT-PCR) method, for detection of turkey rhinotracheitis virus (TRTV). Two sets of primers were designed from F protein gene sequence of TRTV 3B strain. Sensitivity of detection by nested PCR with the primers corresponded to 0.4 TCID50. Applying this method to a field case of swollen head syndrome (SHS), TRTV could be detected directly from chicken trachea and turbinates. It was identified that this method was very useful to examine the relation of TRTV and SHS.

Animals↗