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Biomedical subjects

H Okamoto

Publications and source records attributed to H Okamoto.

At least 109 records · Page 6Linked to original sources
PubMed2001

Operational modes for transient isotachophoretic preconcentration-capillary zone electrophoresis and detectable concentration of rare earth ions.

Operational modes for transient isotachophoretic preconcentration capillary zone electrophoresis (tr-ITP-CZE) were studied by using 5 microM and 0.5 microM rare earth mixtures as analytes in comparison with field-enhanced sample stacking. After examination of several operational modes for tr-ITP, it was found that tr-ITP effectively occured even if both the leading electrolyte and the terminating electrolyte were injected after the sample plug. This was explained as the result of a field-enhanced stacking for both sample components and the leading and terminating ions. The observed theoretical plate numbers were 4-20 times higher than those obtained by normal stacking; and the estimated low limit of detectable concentration of rare-earth elements (REE) was ca. 0.1 microM which was 2.5 times lower compared to normal stacking. For the 0.5 microM sample, a concentration factor of 20 000 could be achieved after only tr-ITP.

Electrolytes↗
PubMed2001

Luciferase expression 2 years after DNA injection in glass catfish (Kryptopterus bicirrhus).

Glass catfish (Kryptopterus bicirrhus) have transparent muscles and skin. Intramuscular injection of DNA encoding luciferase into these fish induced luciferase expression that was measurable in vivo with a low light video image analyser. Expression could be detected up to at least 2 years after DNA injection. Although luciferase is not representative of all types of antigen, this study stresses the need for future studies directed to limit the period of antigen expression after DNA vaccination.

Animals↗
PubMed2001

Complete suppression of insulitis and diabetes in NOD mice lacking interferon regulatory factor-1.

Interferon regulatory factor-1 (IRF-1), a transcriptional factor, regulates type I interferon and interferon-induced genes. It was reported that IRF-1 regulates important molecules required for inflammation and immune reactions. To investigate the role of IRF-1 in the development of autoimmune diabetes, we established IRF-1 deficient (IRF-1(-/-)) non-obese diabetic (NOD) mice. IRF-1-deficient C57BL/6J mice were out-crossed to NOD mice, and F1 were backcrossed to NOD mice. At the N8 generation, the heterozygote for IRF-1 mutation was intercrossed and N8F1 was obtained. Out of three NOD genotypes, IRF-1(+/+) and IRF-1(+/-) developed spontaneous diabetes with an incidence of 47% (9/19) and 50% (10/20) by 30 weeks of age, respectively; whereas IRF-1(-/-) did not develop diabetes (0/18, P< 0.01 vs. (+/+) and (+/-)). Histologically, IRF-1(+/+) and IRF-1(+/-) had various degrees of insulitis, but IRF-1(-/-) had no insulitis. In comparison with IRF-1(+/+), the percentage of CD4(+) and Mac-1(+) splenic cells significantly increased, whereas CD3(+), CD8(+) and B220(+) cells decreased in IRF-1(-/-). Furthermore, spleen cell proliferation in response to Con A or murine GAD65 peptide, a major autoantigen of the pancreatic beta-cell, significantly increased, and the IFN-gamma/IL-10 ratio in the culture supernatant significantly decreased in IRF-1(-/-), suggesting Th2 deviation in cytokine balance. These results indicate that IRF-1 plays a key role in developing insulitis and diabetes in NOD mice.

Animals↗
PubMed2001

Molecular diversity in zebrafish NCAM family: three members with different VASE usage and distinct localization.

NCAM in vertebrates and its related molecules, apCAM in Aplysia, fasciclin II in Drosophila, and OCAM in mammals, play key roles in various aspects of brain development and functions. In this study, we have identified and characterized three members of the NCAM gene family in zebrafish, designated as zNCAM, zOCAM, and zPCAM. Three molecules exhibit similar domain organization: an amino-terminal signal peptide, five immunoglobulin-like domains, two fibronectin type III-like domains, a transmembrane segment, and a carboxy-terminal cytoplasmic region. A novel molecule zPCAM is most closely related to zNCAM with 66% amino acid identity. Diversity in the extracellular region of zPCAM is generated by insertion of two different types of variable alternatively spliced exons. In situ hybridization analysis revealed that three molecules were specifically expressed by the central and peripheral nervous systems from early developmental stages in region-specific and cell-type-specific manners. For example, zPCAM showed a neuromere-specific segmental expression pattern, while zOCAM first appeared in specific clusters of secondary neurons in the forebrain. These results suggest that each member of the NCAM gene family plays distinct roles in the formation and maintenance of functional neuronal networks in the zebrafish nervous system.

Age Factors↗
PubMed2001

Alternate venous drainage and return of warmed blood combined with continuous hypothermic visceral perfusion. A new adjunct of thoracoabdominal aortic aneurysm repair.

OBJECTIVE: As a new adjunct to surgical repair for a thoracoabdominal aortic aneurysm, we have devised and used visceral perfusion in combination with alternate venous drainage and return of warmed blood in 4 patients. METHODS: Surgical repair of a thoracoabdominal aortic aneurysm of Crawford type III (n = 1) or type IV (n = 3) was performed. During visceral branch reconstruction, hypothermic blood (30-32 degrees C) was perfused continuously to each visceral and renal artery at a total flow rate of 300 ml/min, in combination with alternate venous drainage and return of warmed blood to the inferior vena cava. RESULTS: The visceral and renal perfusion time was 115 +/- 55 (with a range from 52 to 190) minutes. All 4 patients recovered uneventfully. CONCLUSIONS: Alternate venous drainage and return of warmed blood combined with continuous hypothermic visceral perfusion were a useful adjunct to thoracoabdominal aneurysm repair during reconstruction of visceral and renal arteries.

Aged↗
PubMed2001

Aortic valve replacement in a heavily calcified "porcelain" aorta.

Although a heavily-calcified so-called "porcelain" aorta is encountered infrequently, its association presents a formidable problem in cardiac surgery. Here we describe a case of severe aortic stenosis and coronary artery disease combined with the circumferentially calcified aorta. The patient was a 63-year-old man who successfully underwent double coronary artery bypass grafting and aortic valve replacement during hypothermic perfusion through the right axillary artery with endoaortic balloon occlusion, followed by minimal endarterectomy of the calcified plate along the aortotomy, and closure of the aorta buttressed with bovine pericardium under circulatory arrest.

Aortic Diseases↗
PubMed2001

Participation of cyclooxygenases in cutaneous thermal nociception under non-inflamed and inflamed conditions.

OBJECTIVE AND DESIGN: Effects of cyclooxygenase inhibitors on noxious thermal stimuli were investigated in non-inflamed and inflamed rats. MATERIALS: Male Sprague-Dawley rats were used in this study. TREATMENT: Cyclooxygenase inhibitors, indomethacin, mofezolac, NS-398, and JTE-522 were administered orally at a dose of 10 mg/kg 1 h prior to and 4 h after the intravenous injection of lipopolysaccharide (1 mg/kg). METHODS: The nociceptive response was evaluated from the escape latency of foot withdrawal to the thermal stimuli with a beam of light. Expression ofcyclooxygenase was examined by reverse transcription-polymerase chain reaction. RESULTS: In normal rat, administration of indomethacin, relatively cyclooxygenase-1-selective inhibitor, mofezolac, or cyclooxygenase-2-selective inhibitors, NS-398 and JTE-522 had no effects on the escape latency against thermal stimuli. Injection of lipopolysaccharide into rat induced the expression of mRNA for cyclooxygenase-2 in the subcutaneous tissue of foot pad. The escape latency at 8 h was significantly shortened by the injection. This hyperalgesia could be reversed by pretreatment of rat with NS-398 or JTE-522, but not with mofezolac. CONCLUSIONS: Cyclooxygenases may have little participation in peripheral skin thermal nociception in non-inflamed condition, although cyclooxygenase-2 could be responsible for the hyperalgesia during inflammation induced by lipopolysaccharide.

Animals↗
PubMed2001

Differential in vitro effects of IL-4, IL-10, and IL-13 on proinflammatory cytokine production and fibroblast proliferation in rheumatoid synovium.

The purpose of this study was to compare the potential of interleukin-4 (IL-4), IL-10, and IL-13 to interrupt two major inflammatory pathways in rheumatoid arthritis (RA), i.e., overexpression of proinflammatory cytokines and cytokine-mediated fibroblast growth. IL-4, IL-10, and IL-13 were all able to significantly inhibit the production of IL-1beta, tumor necrosis factor-alpha (TNF-alpha), IL-6, and IL-8 by freshly isolated RA synovial tissue cells, IL-10 was most effective in terms of IL-1beta and TNF-alpha reduction. The IL-1 receptor antagonist was enhanced by IL-4 and IL-13, but only slightly enhanced by IL-10. Spontaneous interferon-gamma secretion was diminished by IL-4 and IL-10 but not by IL-13. Addition of anti-IL-10 neutralizing antibody to RA synovial tissue cells resulted in a substantial increase in IL-1beta and TNF-alpha levels, whereas neither anti-IL-4 nor anti-IL-13 antibody had a significant effect. IL-1beta-stimulated proliferation of RA synovial fibroblast cell lines was inhibited by IL-4 and IL-13, but not by IL-10; IL-4 was over tenfold more effective than IL-13. These results suggest that IL-4, IL-10, and IL-13 all have the therapeutic potential to regulate the disease activity mediated by proinflammatory cytokines in RA, but each cytokine may have different potencies.

Arthritis, Rheumatoid↗
PubMed2001

Characteristics of recurrent hepatocellular carcinoma in Japan and our surgical experience.

A nationwide survey conducted by the Liver Cancer Study Group of Japan showed that approximately 85%-90% of recurrences of hepatocellular carcinoma (HCC) were in the remnant liver, and that the location of the intrahepatic recurrence was widely distributed throughout the entire liver, with 30%-40% of the recurrences on the side opposite the primary tumor, beyond Cantlie's line. In our experience, about 70% of the recurrences were seen within 2 years after surgery, and the survival rate tended to be lower as the period from the primary surgery to the recurrence was shorter. To achieve longer survival in patients with HCC, one of the most important issues is, therefore, how to prevent and control intrahepatic recurrence after surgery. Although, according to the nationwide survey, repeat hepatectomy has been performed in only 1.6% of all patients with intrahepatic recurrence, we have experienced 28 patients with repeat hepatic resection. The 1-, 3-, and 5-year survival rates from the time of re-resection were 93%, 59%, and 47%, respectively, and survival rates from the time of the initial surgery were 85% at 3 years, 62% at 5 years, and 53% at 8 years. In particular, in patients with a second primary cancer from multicentric carcinogenesis, the 5-year survival rate after the re-resection was approximately 80%. These results suggested that repeat hepatectomy should be recommended for selected patients.

Adult↗
PubMed2001

Molecular epidemiology of TT virus (TTV) and characterization of two novel TTV genotypes in Indonesia.

The prevalence of TT virus (TTV) DNA among 244 healthy individuals in 23 cities on 12 islands in Indonesia was determined by polymerase chain reaction (PCR) with primers derived from the coding region (N22), which can detect TTV DNA of genotypes 1-6. By N22 PCR, TTV DNA was detected in 102 (42%) individuals. The amplified PCR products were molecularly cloned and three clones each were subjected to sequence analysis. Three hundred one (98%) of the 306 TTV clones were classified into genotype 1, 2 or 3, and none into genotypes 4-6. The remaining five clones from two individuals (Kt-08 and Kt-10) on Kutai, Kalimantan Island, differed by >30% from known TTV isolates of all 21 genotypes and were tentatively classified into genotypes 22 and 23, respectively. Using primers specific for the new TTV genotype 22 or 23, TTV genotype 22 was detected significantly more frequently in Kutai than in the other 22 cities (41% vs. 5%, P < 0.001). TTV genotype 23 was restricted to Kutai (17% vs. 0%, P < 0.001), suggesting the indigenous nature of this genotype. Analysis of two TTV isolates (Kt-08F and Kt-10F) demonstrated the extreme diversity of TTV and the preservation of the genomic organization and transcription profile.

Adult↗
PubMed2001

Functional repression of Islet-2 by disruption of complex with Ldb impairs peripheral axonal outgrowth in embryonic zebrafish.

Islet-2 is a LIM/homeodomain-type transcription factor of the Islet-1 family expressed in embryonic zebrafish. Two Islet-2 molecules bind to the LIM domain binding protein (Ldb) dimers. Overexpression of the LIM domains of Islet-2 or the LIM-interacting domain of Ldb proteins prevented binding of Islet-2 to Ldb proteins in vitro and caused similar in vivo defects in positioning, peripheral axonal outgrowth, and neurotransmitter expression by the Islet-2-positive primary sensory and motor neurons as the defects induced by injection of Islet-2-specific antisense morpholino oligonucleotide. These and other experiments, i.e., mosaic analysis, coexpression of full-length Islet-2, and overexpression of the chimeric LIM domains derived from two different Islet-1 family members, demonstrated that Islet-2 regulates neuronal differentiation by forming a complex with Ldb dimers and possibly with some other Islet-2-specific cofactors.

Animals↗
PubMed2001

Identification of ephrin-A3 and novel genes specific to the midbrain-MHB in embryonic zebrafish by ordered differential display.

Development of the tectum and the cerebellum is induced by a reciprocal inductive signaling between their respective primordia, the midbrain and the midbrain/hindbrain boundary (MHB). We set out to identify molecules that function in and downstream of this reciprocal signaling. Overexpression of LIM domain of the transcription factor Islet-3 (LIM(Isl-3)) leads to inhibition of this reciprocal signaling and to resultant defects in tectal and cerebellar development. We therefore searched for genes that may be either up- or down-regulated by overexpression of LIM(Isl-3) by comparing the gene expression profiles in the midbrain and the MHB of normal embryos and embryos in which Islet-3 function was repressed, using a combination of ordered differential display and whole-mount in situ hybridization. Among genes identified in this search, two cDNA fragments encoded Wnt1 and FGF8, which are already known to be essential for the reciprocal signaling between the midbrain and the MHB, confirming the effectiveness of our strategy. We identified four other partial cDNA clones that were specifically expressed around the MHB, ten cDNAs specifically expressed in the tectum, and three cDNAs expressed in neural crest cells including those derived from the midbrain level. The ephrin-A3 gene was specifically expressed in posterior tectum in a gradient that decreased anteriorly. Although ephrin-A2 and ephrin-A5 have been reported to be expressed in the corresponding region in mouse embryos, the superior/inferior colliculi, mouse ephrin-A3 is not expressed prominently in this region, suggesting that the role of ephrin-A3 in brain development may have been altered in the process of brain evolution.

Amino Acid Sequence↗
PubMed2001

Silencing of transposable elements in plants.

Plant genomes contain many transposable elements, most of which are inactivated or 'silenced'. Recent studies have brought significant new insights into the regulation of transposable elements. In Caenorhabditis elegans, they are silenced post-transcriptionally, whereas transposable elements in Arabidopsis are silenced by a chromatin-remodelling factor, one of the components of transcriptional gene silencing. These observations provide the functional correlation between gene silencing and the suppression of transposable elements, and have major implications for our understanding of the maintenance of genomic integrity.

Animals↗
PubMed2001

Influence of TT virus on the clinical course of alcoholic liver disease.

The sera of 43 patients with alcoholic liver disease (ALD) who abstained from alcohol for 4 weeks, were tested for TT virus (TTV) DNA by polymerase chain reaction (PCR) using three different primer pairs (UTR PCR, N22 PCR and genotype-1 PCR). The clinical course of the TTV DNA-positive and -negative groups was compared. By UTR PCR which detects all TTV genotypes, TTV DNA was detected in 40 patients (93%). N22 PCR which detects primarily TTV genotypes 1-6, detected TTV DNA in 17 patients (40%). The alanine aminotransferase (ALT) level 4 weeks after the start of abstinence was significantly higher and the rate of change in ALT {[(ALT on admission-ALT 4 weeks after abstinence)/(ALT on admission)]x100} was lower in the patients who were positive by N22 PCR, than in those who were negative by N22 PCR. Twelve patients (28%) were positive for TTV genotype 1. In the TTV genotype 1-positive group, the ALT 4 weeks after the start of abstinence was significantly higher, and the improvement rates of ALT, gamma-glutamyl transpeptidase and alkaline phosphatase levels were lower than those in the TTV genotype 1-negative group. These results suggest that certain genotypes of TTV may interfere with the improvement of liver function following the start of abstinence in ALD patients.

Journal Article↗
PubMed2001

Influence of TT virus infection on the thrombocytopenia of patients with chronic liver disease.

TT virus (TTV) can replicate not only in the liver but also in hematopoietic cells. To investigate the possible influence of TTV infection on the hematological parameters of patients with chronic liver disease, serum samples from 581 patients with chronic, viral or non-viral liver disease were tested for TTV DNA by polymerase chain reaction (PCR). PCR was performed by two distinct methods using N22 primer pairs (N22 PCR), which detect primarily the four major TTV genotypes (1-4), and using genotype 1-specific primers (Genotype 1-PCR). Thirteen hematological parameters measured in routine laboratory tests were compared among the patients who were positive or negative for TTV infection. The platelet count was significantly lower in the N22 PCR-positive group than in the N22 PCR-negative group among the 189 patients with chronic hepatitis C (CH-C) and among the 40 patients with chronic hepatitis without serological markers of ongoing hepatitis B virus or hepatitis C virus infection (CH-NBNC) (P<0.0001, P<0.005, respectively). Similarly, among the patients with CH-C or CH-NBNC, the platelet count was significantly lower in the TTV genotype 1-positive group than in the TTV genotype 1-negative group (P<0.001, P<0.05, respectively). The reduced platelet count of the TTV DNA-positive group was observed in every fibrotic stage of chronic hepatitis (F0-F3). These results suggest that infection of TTV of certain genotypes including genotype 1 may worsen the thrombocytopenia of patients with CH-C or CH-NBNC, irrespective of the degree of hepatic fibrosis.

Journal Article↗
PubMed2001

TT virus infection in cases of fulminant hepatic failure-evaluation by clonality based on amino acid sequence of hypervariable regions.

The significance of TT virus (TTV) infection in the pathogenesis of acute liver disease is uncertain. Serum TTV-DNA was determined by polymarase-chain reaction (PCR) methods using both hemi-nested (NG059/NG063 and NG061/NG063) and single-step (T801/T935) primers in four patients with fulminant hepatic failure and one patient with late onset hepatic failure in whom hepatitis A virus (HAV) and hepatitis B virus (HBV) markers were negative. Of these five patients, the TTV-DNA was positive in two patients with fulminant hepatic failure by both PCRs before receiving blood transfusion and/or blood-products infusion. Therapies including plasma exchange with blood hemodiafiltration was performed in both patients, and one survived. The non-survivor was an 18-year-old woman with TTV genotype 2 infection. In this patient, the TTV-DNA by PCRs with both primers was positive transiently when serum ALT levels were elevated. The survivor was a 78-year-old woman with infections of TTV genotype 1b and hepatitis C virus (HCV), in whom serum ALT levels returned to normal at 3 weeks after the start of the therapies, but fluctuated after 10 weeks. TTV-DNA measured by hemi-nested primers and HCV-RNA were negative when serum ALT levels decreased, but became positive later. Semi-quantitative PCR using single-step primers revealed that serum TTV-DNA levels changed in correlation with both serum ALT and HCV-RNA levels. Amino acid sequences of hypervariable regions were identical in six out of nine clones isolated from the sera before the therapies and sequence divergence was minimal even in the other three clones, suggesting that TTV proliferated with clonality in the process of fulminant hepatic failure. We conclude that clonally proliferating TTV may contribute to fulminant hepatic failure as a solitary infectious agent or a co-infectious agent with HCV.

Journal Article↗
PubMed2001

Long-wavelength red light emission from TV and photosensitive siezures.

PURPOSE: We investigated a role of long-wavelength red light emission from TV in the induction of photosensitive seizures by an animated TV program called "Pocket Monsters". METHODS: The luminance energy of recorded color bar was measured by a spectroradiometer in cathode-ray tubes (CRTs) of photosensitive patients with and without seizures on the program (induced patients and photosensitive controls). RESULTS: The mean ratio of long-wavelength red light to total visible range was significantly higher in the CRTs of induced patients than in the CRTs of photosensitive controls. The ratio of luminance energy between at turn-on and at 60 min after turn-on of the CRTs indicated that luminance energy in long-wavelength red range from the CRTs of induced patients increased significantly after turn-on of CRTs. CONCLUSIONS: High amounts of long-wavelength red light emitted from CRTs might play an important role in induction of photosensitive seizures in "Pokemon" incident.

Adolescent↗