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S Morikawa

Publications and source records attributed to S Morikawa.

At least 19 recordsLinked to original sources
PubMed1999

Identification of the canarypox virus thymidine kinase gene and insertion of foreign genes.

We mapped the canarypox virus (CaPV) thymidine kinase (TK) gene within a 5.8-kbp XbaI fragment of the genome by Southern blotting using the fowlpox virus (FPV) TK gene as a probe. Nucleotide sequence analysis of the fragment revealed seven open reading frames (ORFs) showing gene organization similar to that of FPV. The TK gene contained in this region had an ORF of 179 amino acids encoding a polypeptide with a putative molecular mass of 20.0 kDa. An A/T-rich region and a transcription termination signal, TTTTTAT, were found upstream and at the end of the ORF, which is consistent with poxvirus early gene regulation. The consensus sequence of the late promoter TAAAT also overlapped with the initiation codon of the ORF. The amino acid sequence similarity between the TK genes of CaPV and FPV, avipoxviruses, was 64.2%, which was lower than the similarities between vaccinia and variola orthopoxviruses (97.2%) and between Shope fibroma and myxoma leporipoxviruses (82.6%). However, the monophyly of avian clades of CaPV and FPV was supported by phylogenetic analysis. We then inserted the genes encoding lacZ, luciferase (luci), and envelope of human T-lymphotropic virus type 1 (HTLV-1 env) into the TK gene of CaPV to evaluate its suitability as an expression vector. The recombinant viruses obtained were unstable, although the foreign genes were expressed efficiently in the mammalian cells infected with the viruses.

Amino Acid Sequence↗
PubMed1999

Myocardial high-energy phosphates and hepatic redox state in jaundiced rats.

BACKGROUND: The mechanism underlying the fatal complications in jaundiced states after shock has not been fully clarified. The present study was designed to examine the effect of hemorrhagic shock on myocardial high-energy phosphate stores and the arterial ketone body ratio (AKBR:acetoacetate/beta-hydroxybutyrate), which reflects the redox state of the liver mitochondria, in normal and jaundiced rats. MATERIALS AND METHODS: At 1 week after ligation of the common bile duct, hemorrhagic shock was induced by exsanguination (mean arterial blood pressure = 40 mmHg) and maintained for 2 h. Serial changes in AKBR were measured. The myocardial adenine nucleotides phosphocreatine (PCr) and inorganic phosphate (Pi) were determined before and after hemorrhagic shock. RESULTS: Before shock, myocardial ATP in the jaundiced group was lower than that in the sham group. However, the myocardial PCr levels in the two groups did not differ. After reinfusion of the shed blood, ATP and PCr recovered to the preshock levels in the sham group. However, ATP and PCr were further increased in the jaundiced group. At 60 min after reinfusion, AKBR recovered to the normal level in the sham group, but decreased below 0.7 in the jaundiced group. Metabolic acidosis was more severe in the jaundiced group than in the sham group. CONCLUSIONS: The decrease in AKBR indicated irreversible metabolic acidosis. As a result, fatal circulatory failure occurred, although the phosphoenergetic level in the myocardium was sufficiently maintained.

Acidosis↗
PubMed1999

Renal ischemia/reperfusion remotely improves myocardial energy metabolism during myocardial ischemia via adenosine receptors in rabbits: effects of "remote preconditioning".

OBJECTIVES: This study examined the changes in myocardial energy metabolism during myocardial ischemia after "remote preconditioning" and investigated the involvement of adenosine receptors in the mechanisms of this effect. BACKGROUND: Recent studies have indicated that a brief period of ischemia and reperfusion (ischemic preconditioning, PC) in a remote organ reduces myocardial infarct size (IS) protecting against subsequent sustained myocardial ischemia. However, the mechanisms of "remote PC" remain unclear. We assessed myocardial energy metabolism during sustained myocardial ischemia and reperfusion after renal PC (RPC), in comparison with that after myocardial PC (MPC) in open-chest rabbits. It has been established that adenosine receptors are involved in the mechanisms of MPC. METHODS: Rabbits that had been anesthetized with halothane were divided into six groups. The control (CNT) group underwent 40-min coronary occlusion followed by 120 min reperfusion. Before the procedure, the MPC group underwent an additional protocol of 5 min coronary artery occlusion and 20 min reperfusion, and the RPC group received a 10 min episode of renal artery occlusion and 20 min reperfusion. In additional experimental groups, 8 sulfophenyl-theophylline (SPT, 10 mg/kg), an adenosine receptor inhibitor, was intravenously injected before the 40 min myocardial ischemia (SPT, MPC + SPT and RPC + SPT groups, respectively). Myocardial levels of phosphocreatine (PCr), ATP and intracellular pH (pHi) were measured by 31P-NMR spectroscopy. RESULTS: RPC and MPC delayed the decreases in ATP levels, preserved pHi during 40-min myocardial ischemia and resulted in better recovery of ATP and PCr during 120 min reperfusion compared with the controls. SPT abolished the improvement in myocardial energy metabolism and the reduction in myocardial IS caused by MPC or RPC. Myocardial IS in the CNT (n = 8), MPC (n = 9), RPC (n = 9), SPT (n = 6), MPC + SPT (n = 8) and RPC + SPT (n = 8) groups averaged 42.8+/-3.5%, 18.2+/-1.8%*, 19.6+/-1.3%*, 44.9+/-5.0%, 35.6+/-2.7% and 34.8+/-3.6% of the area at risk (*p < 0.05 vs. CNT), respectively. CONCLUSIONS: PC in a remote organ, similar to MPC, improved myocardial energy metabolism during ischemia and reperfusion and reduced IS in vivo by an adenosine-dependent mechanism in rabbits.

Adenosine Triphosphate↗
PubMed1998

Distribution of myenteric NO neurons along the guinea-pig esophagus.

Intrinsic nitrergic (NO) neurons of the guinea-pig esophagus were histologically studied to elucidate the physiological significance of the myenteric plexus located in the esophageal striated muscle and smooth muscle of the lower esophageal sphincter. Double staining for PGP 9.5 immunohistochemistry and NADPH-diaphorase histochemistry, which depicts whole neuronal elements and nitrergic NO neurons, respectively, revealed that the plexus had different network patterns along the entire course of the esophagus, and that NADPH-diaphorase positive neurons made up on average 69% of the total number of myenteric neurons. Motor endplates of the esophageal striated muscles that were stained by acetylcholinesterase histochemistry, were often observed in association with NADPH-diaphorase positive varicose fibers that were traced to the myenteric ganglia, though their direct continuity with the neuronal cell bodies could not be ascertained. We conclude that the myenteric NADPH-diaphorase positive neurons in the guinea-pig esophagus contribute to the innervation of the striated muscles as well as the smooth muscles of the lower esophageal sphincter.

Animals↗
PubMed1998

Measurement of local cerebral blood flow by magnetic resonance imaging: in vivo autoradiographic strategy using 17O-labeled water.

Local cerebral blood flow (LCBF) was measured in cats by magnetic resonance imaging (MRI), using 17O-labeled water (H[2]17O) as a tracer. Cat brain images were obtained using a 256 x 240 matrix fast spin-echo sequence with a total acquisition time of 124 seconds per image. Intravenous injection of H(2)17O and sampling of arterial blood were simultaneously performed during the MRI scan. Injection of H(2)17O over 40 seconds caused a transient decrease in brain signal intensity, from which the changes in H(2)17O concentration of brain tissue were calculated. The concentration of H(2)17O in arterial blood was measured directly by 17O nuclear magnetic resonance (NMR) spectroscopy, and used as an input function for the calculation of LCBF. LCBF was successfully determined using an in vivo autoradiographic strategy in a total of three cats. In one, LCBF measurements were also performed under hypercapnic conditions, and LCBF maps of the cat brain during normocapnia and hypercapnia were constructed. These LCBF maps reflected well the changes in LCBF induced by hypercapnia, which indicated the validity of the used method.

Animals↗
PubMed1998

Gluconeogenesis and phosphoenergetics in rat liver during endotoxemia.

BACKGROUND: During endotoxemia, glucose and energy metabolism varies depending on the stage, severity, and other conditions. In this study, gluconeogenesis from 13C-labeled alanine and phosphoenergetic state in rat liver during the acute phase of endotoxemia were concurrently observed by in vivo 13C and 31P NMR spectroscopy in a noninvasive manner. MATERIALS AND METHODS: Lipopolysaccharide from Escherichia coli (10 mg/kg) was injected intravenously followed by infusion of [3-13C]alanine. In vivo 13C and 31P NMR spectra were alternately collected for 90 min with a 2.0 Tesla CSI Omega System. RESULTS: In our experimental model, endotoxin increased the pulse rate without decreasing the blood pressure and elevated the blood sugar level, which suggests the so-called hyperdynamic state. Even under such conditions, a slight, but significant, impairment of the phosphoenergetic state in the liver (a decrease in ATP and an increase in Pi) was detected with 31P NMR spectroscopy. The 13C peaks of glucose C6 and Glu/Gln C2 of the liver in endotoxemia were significantly lower than those of the control, despite hyperglycemia in endotoxemia. CONCLUSIONS: NMR spectroscopic studies suggest that the endotoxin caused the inhibition of gluconeogenic activity from the infused [3-13C]alanine and the TCA cycle accompanied by a deterioration in the phosphoenergetic state even in the hyperglycemic phase. Since the blood sugar level might be influenced by the systemic utilization of glucose, such direct measurements should prove important in the in vivo evaluation of glucose and energy metabolism in the liver.

Adenosine Triphosphate↗
PubMed1998

HIV-1 Nef binding protein expressed on the surface of murine blood cells.

The Nef protein of HIV-1 binds to and induces apoptotic cytolysis of a broad spectrum of uninfected blood cells of humans and mice independently of CD95 (Fas). A 24-kDa glycoprotein responsible for Nef binding and the Nef-induced apoptosis has been identified on the surface of human CD4+ T cells. Using mouse monoclonal antibodies (mAbs) against the human Nef-binding protein and flow cytometry, we analyzed the expression of a corresponding protein on murine cells. The mAbs were shown to bind to the surface of various murine cell lines including T and B lymphocytes and macrophages, in a fashion similar to the binding by soluble Nef protein. The mAbs competed with the Nef protein in binding to the cell surfaces. Immunoprecipitation of cell membranes revealed a 25-kDa protein recognized by the mAbs. Treatment of the soluble Nef protein with anti-Nef (C terminus) mAb, but not anti-Nef (N terminus) mAb, deprived the Nef of the cell binding activity, indicating that binding site is located in the C-terminal domain. Cross-linking of the cell-bound mAbs with secondary antibodies induced apoptotic cytolysis, which occurred independently of CD95 (Fas). On the other hand, neither the mAbs nor the soluble Nef protein reacted with primary lymphocytes in a resting stage obtained from lymph nodes, thymus and spleen of 5-week-old mice. However, some of the cells, predominantly comprising CD4+ T cells, became positive for the both reactions after mitogenic stimulation with phytohemagglutinin, concanavalin A or lipopolysaccharide of Escherichia coli. These results suggest that the 25-kDa protein on murine cell surfaces corresponds to the human Nef binding protein and is responsible for the Nef-induced apoptosis, and that its expression on the cell surface depends on cellular activation.

Animals↗
PubMed1998

Estimation of volume doubling time and cell loss in an experimental rat glioma model in vivo.

We estimated the volume doubling time (Vd) of the ethyl-nitrosourea-induced rat glioma by serial magnetic resonance imaging, and the results were compared with potential doubling time (Tp) determined immunohistochemically. Vd ranged from 3.3 to 29.2 days (11.3 +/- 7.74) and Tp ranged from 2.3 to 13.3 days (6.81 +/- 3.33). Each tumour showed a wide range of bromodeoxyuridine (BUdR) labelling indices (LI), however, Vd and Tp correlated well with BUdR-LI. Vd was estimated as 17.6 x BUdR-LI-0.63 (R = -0.76, P < 0.001, n = 13) and Tp was estimated as 22.6 x BUdR-LI-1.02 (R = -0.92, P < 0.0001, n = 12). In addition, we compared the apoptotic indices (AI), determined by terminal deoxynucleotidyltransferase (Tdt)-mediated biotinylated dUTP-biotin nick-end labelling (TUNEL) techniques, with BUdR-LI and mitoses indices (MI). The results were: AI = 0.23 + 0.25Ln(BUdR-LI) (R = 0.971, n = 8, P < 0.0001) and AI = 1.05 + 0.29Ln(MI) (R = 0.937, n = 8, P < 0.001). Cell loss factors (CLF) also correlated well with BUdR-LI and MI. However, CLF calculated from Tp and Vd were lower than the values previously presumed, probably because of shorter Vd than true doubling time for tumour cell population. These results suggest that even malignant tumours retain a mechanism of adjusting their growth at least partly.

Animals↗
PubMed1998

Hepatocyte growth factor in human amniotic fluid promotes the migration of fetal small intestinal epithelial cells.

OBJECTIVE: Previously we reported on the abundant existence of hepatocyte growth factor in amniotic fluid. This study was conducted to clarify the effects of hepatocyte growth factor in amniotic fluid on fetal intestinal epithelial cells. STUDY DESIGN: Amniotic fluid samples were obtained from 22 cases at various gestational ages. The effects of amniotic fluid and recombinant human hepatocyte growth factor on proliferation, migration, and morphogenesis of intestine 407 cells (a cell line derived from fetal intestinal epithelial cells) were investigated. RESULTS: The mobility of intestine 407 cells was stimulated by amniotic fluid in proportion to the concentration of hepatocyte growth factor in amniotic fluid with the same effect observed with recombinant human hepatocyte growth factor. This activity was neutralized by addition of antihuman hepatocyte growth factor antibody. Neither increased deoxyribonucleic acid synthesis nor morphogenesis in response to amniotic fluid was identified under the conditions used. CONCLUSION: Amniotic fluid stimulates intestinal epithelial cell migration by way of hepatocyte growth factor in amniotic fluid during development of the fetal intestine.

Amniotic Fluid↗
PubMed1998

Estrogen protects against while testosterone exacerbates vulnerability of the lateral striatal artery to chemical hypoxia by 3-nitropropionic acid.

Gender differences in the vulnerability of the lateral striatal artery (1STR artery) to systemic intoxication with 3-nitropropionic acid (3-NPA, succinate dehydrogenase inhibitor) were studied. Subcutaneous injection of 3-NPA (20 mg/kg once a day for 2 days) induced striatal selective lesions in half of male rats associated with motor symptoms (rolling, paddling, recumbency, etc) while female rats were resistant. Lesions were located in the lateral striata and characterized by astroglial necrotic cell death, enhanced immunoreaction to factor VIII-related antigen, edema, extravasation of IgG and sometimes bleeding. The motor and histological disturbances were highly sex-dependent and modulated by changes in hormonal levels. Males were more susceptible than females. Castration had little effect but ovariectomy enhanced the vulnerability. Replacement therapy with testosterone increased while estradiol or tamoxifen suppressed the vulnerability in ovariectomized females. Investigation of the arterial architecture of the brain often revealed rectangular and acute angled branchings in the centrolateral striatum where the ISTR artery feeds. A parallel in vitro toxicity study demonstrated that an extreme Ca++ overload and a strong cellular swelling resulted in astrocytic cell death. Data suggest that 1STR artery and astrocytes are highly vulnerable to 3-NPA intoxication in males. The greater vulnerability of the ISTR artery may contribute to the pathogenesis of neurodegenerative diseases, striatal bleeding, etc. Protective effects of estrogen and tamoxifen may mediate gender differences often observed in these disorders and suggest their potential use as therapeutic agents for these disorders.

Animals↗
PubMed1998

Radioimmunoassay for TA-0910, a new stable thyrotropin releasing hormone analogue and its metabolite, TA-0910 acid-type, in human plasma and urine.

Radioimmunoassay (RIA) was investigated for the determination of TA-0910 and its main metabolite, TA-0910 acid-type, in human plasma and urine. TA-0910 is a new metabolically stable analogue of thyrotropin releasing hormone (TRH). Antiserum was raised in the rabbit against the 1-fluoro-2,4-dinitrophenyl derivative of TA-0910 or TA-0910 acid-type conjugated to keyhole limpet hemocyanin (KLH). The radioligand was prepared by iodination with 125I of the histidine imidazole ring of TA-0910 or TA-0910 acid-type. Cross-reactivities of anti-TA-0910 or TA-0910 acid-type antiserum for TA-0910, its metabolite and related compounds were low. The calibration range was 0.02-5 ng ml-1 using 100 microliters human plasma or urine. Inter-day variations of TA-0910 and TA-0910 acid-type assay in plasma were 3.5-15.5 and 1.8-9.4%, respectively. The variations of the assay in urine were the same as those in plasma. The recovery of TA-0910 and TA-0910 acid-type spiked in plasma or urine samples was approximately 100%. Furthermore, this method was applied to the determination of TA-0910 and TA-0910 acid-type in human plasma and urine samples, for the evaluation of the pharmacokinetics of TA-0910 in humans. From the results it was demonstrated that he developed RIA was useful for the determination of TA-0910 and TA-0910 acid-type in human plasma and urine, and was applicable to pharmacokinetic studies in humans.

Administration, Oral↗
PubMed1998

Deoxyspergualin preferentially inhibits the growth and maturation of anti-CD40-activated surface IgD+ B lymphocytes.

Deoxyspergualin (DSG), an analogue of spermidin, is a potent immunosuppressive drug with an action quite distinct from that of cyclosporin, rapamycin, or FK506. In this study we investigated the effect of DSG and methyldeoxyspergualin (MeDSG) on the proliferation and differentiation of human B cells stimulated with anti-CD40 MoAb. Highly purified B cells obtained from tonsillar samples were used as target cells. Both agents inhibited the proliferative response of anti-CD40-stimulated B cells in the absence and presence of IL-4, IL-2 or IL-10 in a dose-dependent manner. This inhibitory effect differed markedly among cell populations based on surface IgD expression: strong inhibition of sIgD+ B cells but little inhibition of sIgD- B cells. The drugs also suppressed the production of IgG, IgM and IgA by unfractionated B cells, which suggests that DSG acts against post-switch (sIgD-) B cells. Although the drugs suppressed immunoglobulin synthesis by both sIgD+ and sIgD- B cells, the effect was more marked in the sIgD+ B cells. Analysis of the subclass of IgG secreted by sIgD+ B cells revealed a decline in IgG1 and IgG3 in the presence of DSG. These results suggest that DSG preferentially inhibits the growth and maturation of sIgD+ naive B cells.

Antibodies, Monoclonal↗
PubMed1998

Two major antigenic polypeptides of molluscum contagiosum virus.

A library of molluscum contagiosum virus (MCV) transferred into the cowpox vector expression system was screened with 12 sera from molluscum patients. Two recombinant proteins of 70 and 34 kDa were detected by immunoblotting and mapped to the open-reading frames MC133L and MC084L, respectively. Consensus sites were found between the C-terminus of the 70-kDa MCV protein and the 14-kDa fusion protein of vaccinia and variola virus, and between the 34-kDa MCV protein and the 37.5-kDa viral membrane-associated protein of vaccinia and variola virus. Rabbit antisera against these two proteins were prepared. An immunofluorescence study demonstrated that the 70- and 34-kDa proteins were predominantly expressed on the surface of recombinant virus-infected HeLa cells, indicating the potential to be inserted into the membrane. On immunoelectron microscopy, antiserum against 70-kDa protein showed significant labeling of the MCV membrane, while the antiserum against 34-kDa protein failed to do so.

Amino Acid Sequence↗
PubMed1998

Hepatic energy metabolism during ketamine and isoflurane anaesthesia in haemorrhagic shock.

The effects of ketamine and isoflurane on the phosphoenergetic state of the liver during haemorrhage were investigated using 31P nuclear magnetic resonance (NMR) spectroscopy. Male Wistar rats were anaesthetized with ketamine (1.0 mg kg-1 min-1 i.v., Ket 1.0 group, or 1.5 mg kg-1 min-1 i.v., Ket 1.5 group), or isoflurane 1.4% (Iso group). Haemorrhage was induced by withdrawing blood until the mean arterial pressure was reduced to 40 mm Hg, and this pressure level was then maintained for 45 min. Hepatic energy metabolism was evaluated from the changes in adenosine triphosphate (ATP) and inorganic phosphate (Pi). The beta-ATP decrease and the Pi increase were more marked in the two Ket groups than in the Iso group. At 20 min after haemorrhage, the beta-ATP peak areas were 34%, 32% and 76%, and the Pi peak areas were 257%, 260% and 160% of their initial values in the Ket 1.0, Ket 1.5 and Iso groups, respectively. NMR data were supported by chemical assessments. These results demonstrated that, in terms of phosphoenergetic levels, a continuous administration of 1.0 or 1.5 mg kg-1 min-1 ketamine markedly decreased hepatic metabolism during haemorrhagic shock, whereas inhalation of 1.4% isoflurane mitigates the metabolic damage.

Adenosine Triphosphate↗
PubMed1998

Evaluation of focal cerebral ischemia in rats by magnetic resonance imaging and immunohistochemical analyses.

Correlation of focal ischemia-induced brain damage evidenced by magnetic resonance imaging (MRI) and by staining with microtubule-associated protein 2 (MAP2) was studied in rats. Ischemia was produced by transient occlusion of the middle cerebral artery (MCAO). The damage was assessed at 6 to 8 hours after MCAO and 1 week later. The area of damage assessed by MRI agreed with that by MAP2 staining at 6 to 8 hours after MCAO, which was smaller (P < 0.001) than that defined by MAP2 staining 1 week after MCAO. Glial staining indicated that glial infiltration affected the signal intensity of MRI in the area of damage.

Animals↗
PubMed1998

[Recent clinical aspect of tuberculin reaction].

The tuberculin reaction is the best known and most widely studied form of delayed hypersensitivity and is a clinically acceptable measure of cell mediated immunity. The reaction is characterized by a delayed response to antigenic challenge which is mediated by Th1 cells. This sort of reaction has been thought to form part of the body defenses against a number of infections and infestations. Currently, however, evidence is more favour of a dissociation between allergy and resistance. On the other band it is also evidence that the ability to respond to antimicrobacterial therapy parallel the strength of cell-mediated immune reactivity. Tuberculin test still possess the value as the diagnostic and prognostic parameters for tuberculosis.

Humans↗
PubMed1997

Involvement of hepatocyte growth factor in formation of bronchoalveolar structures in embryonic rat lung in primary culture.

To clarify the role of hepatocyte growth factor (HGF) in embryonic lung development, organoids from fetal rat lung were cultured in collagen gels with or without HGF antisense oligonucleotides. Cyst-like structures formed within 24 h in organoids isolated from fetuses after 14 days' gestation, but this was abolished by the oligonucleotide addition, apparently by interference with the endogenous expression of HGF. Electron microscopy revealed two types of structure: an alveolar type characterized by osmiophilic lamellar bodies in the cytoplasm and lumen, and a bronchial type consisting of epithelial cells bearing microvilli on their apical surfaces. HGF mRNA was detectable from day 14 in fetal lung by RT-PCR. Our results suggest that HGF plays, coordinately with its expression, a crucial role in the morphogenesis of both alveolar and bronchial epithelia in the rat fetal lung.

Animals↗