Biomedical subjects

T Koyama

Publications and source records attributed to T Koyama.

At least 37 records · Page 2Linked to original sources

PubMed2005

PMEA polymer-coated PVC tubing maintains anti-thrombogenic properties during in vitro whole blood circulation.

Poly(2-methoxyethylacrylate) (PMEA) is a new coating material that appears to reduce protein and platelet adsorption. However, the exact performance of PMEA coated circuit remains to be revealed in well-controlled experiments. Therefore, we compared its hemocompatibility with covalent-bound heparin-, and non-coated circuits during 6 hours of in vitro circulation, using donor blood from six volunteers. In our model, simple tubing circuits containing one-way ball valve were placed on the rotary table, which moved alternatively to generate pulsatile recirculation of heparinized human blood inside the tubing. Using this model, we expected fine assessment of the material surface, because we could reduce blood damage by avoiding air and a blood pump. Moreover, the small capacity of circuit allowed us to compare three kinds of circuits using a single unit of donor blood, eliminating effects by possible variations between blood donors. The anti-thrombin capacity of the PMEA-coated circuits was maintained even after six hours blood circulation, whereas surface thrombin generation increased markedly after use in non-coated circuits (P<0.05). Deposition of fibrin onto PMEA circuits was reduced more than 30% compared with heparin and non-coated circuits (P<0.05). However, the increase of plasma Factor XIIa was similar in all circuits. Increase of CD11b expression on circulating leukocytes and of plasma C3a was ameliorated in the heparin- and PMEA-coated circuits (P<0.05). PMEA-coated circuits appear to maintain their anti-thrombogenicity during use, otherwise PMEA-coated and heparin-coated circuits showed a similar character in hemocompatibility. This long-standing anti-thrombogenicity might be attributable to less adsorption of activated blood components onto the surface.

Acrylates↗

PubMed2004

Raised serum APRIL levels in patients with systemic lupus erythematosus.

OBJECTIVE: To determine whether serum levels of a proliferation-inducing ligand (APRIL) are raised in patients with systemic lupus erythematosus (SLE) and correlate with autoantibody titres or disease activity, or both. METHODS: Serum samples from 48 patients with SLE, 41 normal healthy subjects, and 21 patients with rheumatoid arthritis (RA) were assayed for APRIL by enzyme linked immunosorbent assay. Medical charts were retrospectively reviewed for autoantibody titres and immunoglobulin levels. Disease activity was assessed using the British Isles Lupus Assessment Group (BILAG) index. RESULTS: The APRIL levels in the serum samples from patients with SLE were significantly higher than in those from healthy controls and those from patients with RA. Serum APRIL levels did not correlate with serum IgG and IgM levels, but had a tendency to correlate with anti-double stranded DNA antibody titres. Moreover, serum APRIL levels correlated significantly with musculoskeletal manifestations among patients with SLE when assessed by the BILAG index. CONCLUSION: APRIL may be an important factor in raised autoantibody titres and musculoskeletal disease in patients with SLE. Patients with raised serum APRIL levels may be ideal candidates for therapeutic targeting of APRIL.

Adult↗

PubMed2004

Vertical transmission of Neospora caninum in BALB/c mice in both acute and chronic infection.

To examine the frequency of congenital infection by Neospora caninum, BALB/c mice were inoculated intraperitoneally with tachyzoites of N. caninum either during pregnancy (Group 1) or 4 weeks or more before pregnancy (Group 2). Further, the mice inoculated during pregnancy were bred at 4 weeks or more after delivery to form Group 3. Congenital transmission was observed in 76% of the neonates of the mice in Group 1 and in 50% of the neonates of the mice in Group 2. Interestingly, congenital transmission was observed in 86% of the neonates from Group 3. These results suggest that chronically-infected BALB/c mice efficiently transmit N. caninum infection to their offspring.

Animals↗

PubMed2004

Characteristics of postictal headache in patients with partial epilepsy.

Migraine-like features sometimes characterize the headache that follows epileptic seizure (postictal headache, PIH). We compared patients with different types of epilepsy to investigate the association between migraine-like PIH and seizure type. Subjects comprised 364 patients with partial epilepsy. Epilepsy types were temporal lobe epilepsy (TLE, n = 177), frontal lobe epilepsy (FLE, n = 116), and occipital lobe epilepsy (OLE, n = 71). Patients participated in a structured interview pertaining to PIH as well as interictal headache and family history of migraine. Headaches were classified according to the International Headache Society criteria, which was modified for this study. Forty percent had PIH and 26% of these patients had migraine-like PIH. Migraine-like PIH occurred significantly more often in cases of TLE and OLE than in cases of FLE. In addition, the incidence of interictal migraine headache was significantly higher in patients with migraine-like PIH. These results suggest that migraine-like PIH is related to particular regions of epileptogenic focus and that susceptibility to migraine headache predisposes to migraine-like PIH.

Adolescent↗

PubMed2004

[Oral sildenafil citrate as an effective alternate in the treatment of postoperative pulmonary hypertensive crisis after congenital heart surgery].

A five-month-old girl of Down syndrome underwent a corrective surgery for complete atrioventricular septal defect. Her postoperative course was complicated with pulmonary hypertensive (PH) crises despite nitroglycerin (NTG) infusion and inhaled nitric oxide (NO). Sildenafil citrate, a phosphodiesterase 5 inhibitor, was administered through a nasogastric tube at a starting dose of 0.3 mg/kg by stepwise increment to the maximum dose of 2 mg/kg 4 hourly. Sildenafil citrate dramatically lowered pulmonary arterial pressure and the patient was weaned from NTG and NO without PH crisis. There was no side effect after sildenafil citrate administration. Oral sildenafil citrate is a safe and potent adjunct to the existing therapies for postoperative PH in infants after open heart surgery.

Administration, Inhalation↗

PubMed2003

Effects of NRA0045, a novel potent antagonist at dopamine D4, 5-HT2A, and alpha1 adrenaline receptors, and NRA0160, a selective D4 receptor antagonist, on phencyclidine-induced behavior and glutamate release in rats.

RATIONALE: Administration of phencyclidine (PCP) to animals produces abnormal behavior such as hyperlocomotion, stereotyped behavior, and ataxia; this abnormal behavior is only weakly blocked by dopamine D(2) receptor antagonists. This study examined the effects of a novel thiazole derivative, NRA0045 which potently antagonizes not only dopamine D(4) receptors but also 5-HT(2A) and alpha(1) adrenaline receptors, and NRA0160, a selective dopamine D(4) receptor antagonist, on PCP-induced abnormal behavior, and accompanying increases in extracellular levels of glutamate in the medial prefrontal cortex. Furthermore, this study compared the effects of these drugs with those of clozapine and haloperidol. METHODS: To study the effects of NRA-drugs, atypical and typical antipsychotics, we measured locomotor activity with an infra-red sensor, and stereotypy and ataxia on a rating scale. Extracellular glutamate levels were measured by in vivo microdialysis. RESULTS: NRA0045 (1 or 3 mg/kg) or clozapine (1 mg/kg) attenuated hyperlocomotion, stereotypy, and ataxia induced by PCP (7.5 mg/kg) without affecting behavior after saline injection. Although haloperidol (0.1 or 1 mg/kg) attenuated or inhibited PCP-induced behavior, this drug also affected behavior after saline injection. NRA0160 (0.1, 1, or 3 mg/kg) had no effect on behavior induced by PCP or saline. NRA0045 (3 mg/kg), but not NRA0160, inhibited PCP-induced increases in glutamate levels in the medial prefrontal cortex. PCP-induced hyperlocomotion correlated with the PCP-induced increases in glutamate levels in this brain region. CONCLUSIONS: These results suggest that the effects of NRA0045 on PCP-induced abnormal behavior are similar to those of the atypical antipsychotic clozapine. NRA0045 probably attenuates PCP-induced abnormal behavior by inhibiting the PCP-induced increase in glutamate levels in the medial prefrontal cortex; this inhibition may be mediated via the blockade of 5-HT(2A) receptors.

Adrenergic alpha-1 Receptor Antagonists↗

PubMed2003

Mutations in the ST7/RAY1/HELG locus rarely occur in primary colorectal, gastric, and hepatocellular carcinomas.

Human cancers frequently show a loss of heterozygosity on chromosome 7q31, which indicates the existence of broad-range tumour-suppressor gene(s) at this locus. Truncating mutations in the ST7 gene at this locus are seen frequently in primary colon cancer and breast cancer cell lines. Therefore, the ST7 gene represents a novel candidate gene for the tumour suppressor at this locus. However, more recent studies have reported that ST7 mutations are infrequent or absent in primary cancer and cell lines. To ascertain the frequency of mutations of the ST7 gene in cancer cells, we examined mutations in the ST7 coding sequence in 48 colorectal, 48 gastric, and 48 hepatocellular carcinomas using polymerase chain reaction-single-strand conformational polymorphism and direct sequencing. We detected somatic mutations, which were located near the exon-intron junction in intron 8, in only three out of 144 cases. We conclude that mutations in the ST7 gene are rare in primary colorectal, gastric, and hepatocellular carcinomas.

Bacterial Proteins↗

PubMed2003

Increase of Th1 type cytokine mRNA expression in peripheral blood lymphocytes of calves experimentally infected with Cryptosporidium parvum.

The expression of the messenger RNA of interleukin-12 (IL-12), interferon-gamma, interleukin-4, interleukin-6, and interleukin-10 was examined by reverse-transcriptase polymerase chain reaction in peripheral blood lymphocytes of calves that were orally inoculated with Cryptosporidium parvum oocysts. In all of the calves, gene expression of interleukin-12, interleukin-6, and interferon-gamma was observed at delivery and this expression was repressed within the next 24h. In calves inoculated with C. parvum, mRNA expression of interleukin-12 and interferon-gamma was noticed on day 3 post-inoculation (p.i.) and increased in the convalescent phase of the infection, whereas in non-inoculated calves no mRNA expression was detectable up to the end of the experiment. No mRNA expression of interleukin-4 or 6 was detected during the experiment. Our observations suggest that systemic Th1 type immune responses are induced in calves infected with C. parvum and may be available for evaluation of the control of the infection.

Animals↗

PubMed2003

Molecular breeding of transgenic rice expressing a xylanase domain of the xynA gene from Clostridium thermocellum.

The gene encoding the catalytic domain of thermostable xylanase from Clostridium thermocellum F1 was expressed in rice plants under the control of a constitutive promoter. The gene encoding Xylanase A was modified to encode the catalytic domain of family 11 xylanase without the signal sequence (xynA1), and was introduced into rice plants and expressed under the control of a modified cauliflower mosaic virus 35S promoter. Zymogram analysis indicated that the recombinant xylanase was produced in rice plants. The xynA1 gene was stably expressed in rice straw and seed grains. No phenotypic effect of xylanase expression was noted. The enzyme was detected in the desiccated grain. High levels of enzyme activity were maintained in the cell-free extract during incubation at 60 degrees C for 24 h. The results indicated that high levels of xylanase can be produced in rice plants.

Bacterial Proteins↗

PubMed2003

A novel polymorphism of the human APRIL gene is associated with systemic lupus erythematosus.

OBJECTIVE: We investigated the association of gene polymorphisms in APRIL, a new member of the TNF family, with systemic lupus erythematosus. METHODS: To detect polymorphisms of the human APRIL gene by exon-specific polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) analysis, we first determined the structure of the human APRIL gene. We designed exon-specific oligonucleotide primers according to the genomic DNA sequence of APRIL. All of the coding regions in exons of the APRIL gene were analysed by exon-specific PCR-SSCP in 148 SLE patients and 146 unaffected controls, then the nucleotide sequences of exons that displayed aberrant bands were determined. RESULTS: The human APRIL gene comprised at least six exons with five introns, spanning approximately 2.8 kilobases of the genomic DNA. By exon-specific PCR-SSCP, we identified two novel polymorphisms at codons 67 and 96. Both had amino acid substitutions: G67R and N96S respectively. Only the 67G allele was associated with SLE in 148 Japanese SLE patients, with allele frequency 0.662 compared with 0.575 for 146 unaffected controls (P=0.0302). The frequency of the individuals who possessed at least one 67G allele in SLE patients (91.9%) was significantly higher than that in the unaffected controls (80.1%) (P=0.0036). CONCLUSION: The 67G allele of APRIL may be a contributing factor in the pathogenesis of SLE.

Adolescent↗

PubMed2003

Friedel oscillation in charge profile and position dependent screening around a superconducting vortex core.

We calculate microscopically the charge distribution around a vortex in type II superconductors by solving the Bogoliubov-de Gennes equation and the Poisson equation simultaneously. Our calculations show that the charge density depletion occurs in the vortex center and the Friedel oscillation appears over the coherence length when k(F)xi is small. We also calculate the density-density correlation function K(r,r(')) as a function of two spatial variables, r and r('), and find that K(r,r(')) is strongly dependent on the distance from the vortex center. We clarify the spatial dependent screening properties on the basis of the correlation function in the core region.

Journal Article↗

PubMed2003

Changes in salivary cortisol concentrations during a 24-hour period in dogs.

The purpose of this investigation was to clarify whether salivary cortisol secretion in dogs had a circadian rhythm. Saliva sampling during a 24-hour period was performed in 4 non-consecutive days. Eight adult beagle dogs (4 males and 4 females) were divided into 4 groups, and 2 dogs (1 male and 1 female) were used for each repetition. Saliva samples were taken at 1 h intervals from 9:00 a. m. to 9:00 a. m. of the following day. Salivary cortisol concentrations were determined using enzyme-linked immunosorbent assay. No circadian rhythm was detected for salivary cortisol, and the differences among salivary cortisol concentrations measured every hour were not demonstrated during a 24-hour period in dogs.

Animals↗

PubMed2003

Eimeria stiedai merozoite 49-kDa soluble antigen induces protection against infection.

A soluble antigen isolated from Eimeria stiedai merozoites with a molecular mass of 49 kDa was detected in the bile of infected rabbits. Rabbits immunized with the antigen shed a lower number of oocysts than did nonimmunized rabbits postchallenge (p.c.). The immunized rabbits showed a marked and transient increase of alanine-aminotransferase (ALT) activity on day 8 p.c. The blood indocyanine green (ICG) clearance and r-glutamyltransferase (GGT) activity showed no change throughout the experiment However, nonimmunized rabbits showed a gradual increase of ALT and GGT in the plasma and a delay of ICG p.c. Many merozoites were observed in the biliary ducts of the nonimmunized rabbits on day 8 p.c. using standard histology. In contrast, in the immunized rabbits, many inflammatory cells were observed around the biliary ducts, but there were few parasites in the tissue. These results suggest that the 49-kDa soluble protein antigen detected in the bile of the infected rabbits was a merozoite-specific antigen, and the immune reaction to the antigen may induce protective effects against the infection.

Alanine Transaminase↗

PubMed2002

Expression of mRNA of chemokine receptor CXCR4 in feline mammary adenocarcinoma.

The expression of mRNA of the chemokine receptor CXCR4 in 65 surgically resected mammary adenocarcinomas from cats was investigated by in situ hybridisation. No expression of the receptor's mRNA was detectable in the mammary tissue of healthy cats, but it was expressed in areas adjacent to necrosis, surrounding blood vessels and cells infiltrating the lymphatics of 47 (72.3 per cent) of the 65 samples. There was a significant relationship between lymphatic infiltration by neoplastic cells and the expression of the receptor's mRNA (P < 0.005), but there was no significant relationship between its expression and the one-year survival of the cats.

Adenocarcinoma↗

PubMed2002

Effect of MS-153 on the development of behavioral sensitization to locomotion- and ataxia-inducing effects of phencyclidine.

RATIONALE: Repeated administration of phencyclidine (PCP) produces behavioral sensitization to PCP. Although the precise mechanism is unknown, glutamatergic neurotransmission seems to play an important role in the development of sensitization. OBJECTIVES: The present study examined whether a novel compound, MS-153 (( R)-(-)-5-methyl-1-nicotinyl-2-pyrazoline), which has an ability to enhance glutamate uptake and inhibit glutamate release, would block the development of behavioral sensitization to PCP. METHODS: For studying effects of MS-153, locomotor activity was measured by an infrared sensor and ataxia was measured by a rating scale. RESULTS: MS-153 (10 and 100 mg/kg) enhanced locomotion and ataxia induced by a single injection of PCP (7.5 mg/kg). Repeated administration of PCP (20 mg/kg, once in every day, for 5 days) developed sensitization to locomotion- and ataxia-inducing effects of PCP (7.5 mg/kg). MS-153 given 60 min and 120 min later of every PCP treatment blocked the development of behavioral sensitization to both locomotion- and ataxia-inducing effects of PCP. Co-administration of MS-153 with repeated saline treatment did not produce hypersensitivity to PCP. CONCLUSIONS: These results suggest that the attenuation of glutamatergic neural transmission enhances acute effects of PCP, in contrast, blocks the behavioral sensitization developed by repeated PCP treatment. Therefore, glutamatergic neural transmission plays an important role in the development of behavioral sensitization to PCP.

Animals↗

PubMed2002

Pupal commitment and its hormonal control in wing imaginal discs.

The timing of pupal commitment of the forewing imaginal discs of the silkworm, Bombyx mori, was determined by a transplantation assay using fourth instar larvae. The wing discs were not pupally committed at the time of ecdysis to the fifth instar. Pupal commitment began shortly after the ecdysis and was completed in 14 h. When the discs of newly molted larvae (0-h discs) were cultured in medium containing no hormone, they were pupally committed in 26 h. In vitro exposure of 0-h discs to 20-hydroxyecdysone accelerated the progression of pupal commitment. Methoprene, a juvenile hormone analog (JHA), did not suppress the change in commitment in vitro at physiological concentrations. Thus the wing discs at the time of the molt have lost their sensitivity to JH, and 20E is not a prerequisite for completion of pupal commitment. These results suggest that the change in commitment in the forewing discs may begin before the last larval molt.

Journal Article↗

PubMed2002

A case of idiopathic spinal epidural lipomatosis presented with radicular pain caused by compression with enlarged veins surrounding nerve roots.

OBJECTIVE: To report a case of idiopathic spinal epidural lipomatosis (SEDL) presented with unique radicular pain most likely caused by enlarged veins surrounding nerve roots. PATIENT: A 26-year-old male presented with radicular pain of the right T6-T7 area. He also showed Becker's nevus in the corresponding area. CT myelography and magnetic resonance imaging revealed epidural lipomatosis posterior to T4-T8 of the spinal cord. Surgical removal of adipose tissue and a hemilaminectomy of T4-T7 were performed and resulted in relief of the radicular pain. CONCLUSIONS: Lipomatosis was histologically confirmed and surrounded by enlarged veins. These abnormally enlarged veins compressed the nerve roots and were thought to cause radicular pain. Also, Becker's nevus of this case seems to have some relationship with SEDL.

Adult↗

PubMed2002

Effects of diltiazem on in vitro cardiovascular actions of crude venom obtained from Okinawan box-jellyfish (Habu-kurage), Chiropsalmus quadrigatus.

The venom obtained from Okinawan box-jellyfish (Habu-kurage), Chiropsalmus quadrigatus, produced increases in contractions of isolated rat right atrial preparations in a concentration-dependent manner without changes in a spontaneous beating rate. These increases in contractions were significantly inhibited by diltiazem and did not show tachyphylaxis. The venom also produced increases in contractions of isolated rat aortic ring preparations (endothelium-intact) in a concentration-dependent fashion, which were reproducible with repeated application and were significantly inhibited by diltiazem or heating. These increases in vascular contractions were weakened in endothelium-denuded preparations, and almost abolished in a calcium-free medium. On the other hand, the venom at higher concentrations diminished contractions of both myocardial and vascular preparations and did not show reproducibility. These results suggest that the Habu-kurage venom is heat-labile and may increase contractions of cardiac muscle and aortic smooth muscle by increasing calcium influx into muscle cells, and that the venom at higher concentrations may produce dysfunction of muscle contractile systems due to calcium overload.

Animals↗