Biomedical subjects

N Okamoto

Publications and source records attributed to N Okamoto.

At least 19 recordsLinked to original sources

PubMed2002

Cytotoxic T cell function in fish.

Fish possess immunoglobulins, major histocompatibility complex (MHC), T-cell receptors, and lymphocyte populations analogous to B and T cells and can evoke specific immune responses against a variety of antigens. However, T-cell subsets have yet to be demonstrated and the information on cell-mediated immunity is limited. Here we briefly review our recent studies on specific cell-mediated immunity, particularly on cytotoxic T-cell function employing isogeneic fish and cell lines. Analyses of the graft-versus host reaction (GVHR) and cell-mediated cytotoxicity (CMC) against allogeneic erythrocytes or cell lines show alloantigen-specific cytotoxicity in clonal ginbuna crucian carp. We also describe specific cytotoxicity against virus-infected cells using clonal ginbuna and a syngeneic cell line. Lastly, we report MHC-restriction in CMC against virus-infected cells using homozygous clonal rainbow trout and trout cell line which share the same MHC class I allele. These studies on CMC strongly suggest the presence of antigen specific cytotoxic T cells in teleosts and functional similarities between the immune systems of fish and higher vertebrates. Experimental model systems established in these studies can be applied to the investigation of protective antigens to induce cell-mediated immunity for the development of fish vaccines.

Animals↗

PubMed2001

B cell adaptor containing src homology 2 domain (BASH) links B cell receptor signaling to the activation of hematopoietic progenitor kinase 1.

The B cell adaptor containing src homology 2 domain (BASH; also termed BLNK or SLP-65), is crucial for B cell antigen receptor (BCR)-mediated activation, proliferation, and differentiation of B cells. BCR-mediated tyrosine-phosphorylation of BASH creates binding sites for signaling effectors such as phospholipase Cgamma (PLCgamma)2 and Vav, while the function of its COOH-terminal src homology 2 domain is unknown. We have now identified hematopoietic progenitor kinase (HPK)1, a STE20-related serine/threonine kinase, as a protein that inducibly interacts with the BASH SH2 domain. BCR ligation induced rapid tyrosine-phosphorylation of HPK1 mainly by Syk and Lyn, resulting in its association with BASH and catalytic activation. BCR-mediated activation of HPK1 was impaired in Syk- or BASH-deficient B cells. The functional SH2 domain of BASH and Tyr-379 within HPK1 which we identified as a Syk-phosphorylation site were both necessary for interaction of both proteins and efficient HPK1 activation after BCR stimulation. Furthermore, HPK1 augmented, whereas its kinase-dead mutant inhibited IkappaB kinase beta (IKKbeta) activation by BCR engagement. These results reveal a novel BCR signaling pathway leading to the activation of HPK1 and subsequently IKKbeta, in which BASH recruits tyrosine-phosphorylated HPK1 into the BCR signaling complex.

Adaptor Proteins, Signal Transducing↗

PubMed2001

Elucidation of the differences between the 430- and 455-nm absorbing forms of P450-isocyanide adducts by resonance Raman spectroscopy.

Alkylisocyanide adducts of microsomal P450 exist in two interconvertible forms, each giving the Soret maximum around 430 or 455 nm. This is demonstrated with a rabbit liver P450 2B4. Resonance Raman spectra of the 430- and 455-nm forms were examined for typical P450s of the two types as well as for P450 2B4 because the 430-nm form of P450 2B4 is liable to change into P420. P450cam and P450nor were selected as a model of the 430- and 455-nm forms, respectively. For the n-butyl isocyanide (CNBu) adduct, the Fe(II)-CNBu stretching band was observed for the first time at 480/467 cm(-1) for P450cam and at 471/459 cm(-1) for P450nor with their (12)CNBu/(13)CNBu derivatives. For P450cam, but not P450nor, other (13)C isotope-sensitive bands were observed at 412/402, 844/835, and 940/926 cm(-1). The C-N stretching mode was identified by Fourier transform IR spectroscopy at 2116/2080 cm(-1) for P450cam and at 2148/2108 cm(-1) for P450nor for the (12)C/(13)C derivatives. These findings suggest that the binding geometry of isocyanide differs between the two forms-bent and linear structures for P450cam-CNBu and P450nor-CNBu, respectively. In contrast, in the ferric state, the Raman (13)C isotopic frequency shifts, and the IR C-N stretching frequencies (2213/2170 and 2215/2172 cm(-1)) were similar between P450cam and P450nor, suggesting similar bent structures for both.

Animals↗

PubMed2001

Differential expression of max and two types of c-myc genes in a tetraploid fish, the common carp (Cyprinus carpio).

We cloned the full-length cDNA of max gene from the common carp (Cyprinus carpio). The cDNA clone of carp max consists of 1209 bp and contained an ATG-initiated ORF consisting of 156 aa. The carp MAX share 76.7-93.8% aa identity with those of human, mouse, rat, chicken, Xenopus and zebrafish, respectively. The 15 bp alternative splicing was observed in the loop region of helix-loop-helix and is not previously described in mammalian max sequences. Transcripts of max gene were observed in all of the tissues of carp investigated in this study. The highest expression was found in the ovary, and the transcripts in hepatopancreas and heart were low. Two carp c-myc genes (CAM1 and CAM2) showed differential expression pattern. The expression of max was concomitant with CAM2 expression, but not with CAM1. It has been reported that MYC/MAX heterodimer as a regulator of gene expression has been maintained throughout vertebrate evolution, and the expression of c-myc has been concomitant with max expression. In addition, according to phylogenetic analysis, CAM1 is evolving faster than CAM2 after gene duplication. Therefore, this result suggests that CAM1 may evolve to obtain a new function different from c-myc.

Amino Acid Sequence↗

PubMed2001

cDNA sequence of human carbonic anhydrase-related protein, CA-RP X: mRNA expressions of CA-RP X and XI in human brain.

A full-length cDNA clone of human carbonic anhydrase-related protein (CA-RP) X was obtained and sequenced. The 2720 bp long cDNA sequence was predicted to encode a 328 amino acid polypeptide. The deduced amino acid sequence showed an overall similarity of 25-57% to other CA isozymes and the highest % similarity to a CA-RP XI. Similar to CA-RP XI, CA-RP X lacked two out of three zinc-liganded histidine residues, suggesting no biological activity of CA. Northern blot analysis demonstrated an approx. 2.8 kb transcript in the human brain and kidney. RNA dot blotting showed significant signals for CA-RP X and XI mRNA expressions in the adult total brain and almost all parts of the central nervous system, but no expression in the fetal brain. These results suggest that CA-RP X and XI play some role in human brain, especially in brain development.

Amino Acid Sequence↗

PubMed2001

Bernard-Soulier syndrome associated with 22q11.2 microdeletion.

We describe a Japanese girl with Bernard-Soulier syndrome and 22q11.2 microdeletion. She had viral infections and recurrent thrombocytopenia and hemorrhagic diathesis after cardiac surgery. As congenital heart defects and abnormal immunity are the most common clinical manifestations associated with 22q11.2 deletion, patients with this association may have a greater risk of developing a severe bleeding disorder.

Abnormalities, Multiple↗

PubMed2001

Risk factors for sudden unexpected death among workers: a nested case-control study in central Japan.

UNLABELLED: BACKGROUND; Few studies have focused on sudden death among apparently healthy workers, and the risk factors have not been fully discussed. METHODS: A nested case-control study was conducted among 164,017 male employees receiving annual medical checkups in Japan. Most recent medical checkup data of 242 sudden death victims (mean age, 48.0 years) were compared with corresponding data of 505 age-, workplace-, and job-type-matched male controls. Odds ratios (ORs) and their 95% confidence intervals (CIs) for each variable were calculated by logistic regression. RESULTS: OR (95% CI) significantly increased with advancing blood pressure, reaching 6.6 (3.4-13.1) for systolic blood pressure > or =160 mm Hg relative to that <120 mm Hg. Hypo-HDL-cholesterolemia, hyperuricemia, increased aminotransferases, and abnormal urinary findings were associated with the risk in a dose-dependent manner. The presence of arrhythmias and ST-T abnormalities as well as abnormal Q waves on electrocardiograms yielded a 3.5 to 4.8 times greater risk of sudden death. As for lifestyles, heavy smoking was a positive, and light drinking was a negative risk factor. Multivariate analysis revealed that hypertension, proteinuria, glucosuria, arrhythmias, ST-T abnormalities, and light drinking were independent predictors for sudden death. CONCLUSION: These findings suggest that periodic medical checkups can help to predict and prevent employee sudden death.

Blood Pressure↗

PubMed2001

Quantitative trait loci (QTLs) associated with resistance/susceptibility to infectious pancreatic necrosis virus (IPNV) in rainbow trout (Oncorhynchus mykiss).

Infectious pancreatic necrosis (IPN) is a well-known acute viral disease of salmonid species. We have identified quantitative trait loci (QTLs) associated with resistance to this disease in rainbow trout. We searched for linkage among 51 microsatellite markers used to construct a framework linkage map in backcross families of rainbow trout (Oncorhynchus mykiss), produced by crossing IPN-resistant (YN-RT201) and -susceptible (YK-RT101) strains. Two putative QTLs affecting disease resistance were detected on chromosomes A (IPN R S-1) and C (IPN R/S-2), respectively, suggesting that this is a polygenic trait in rainbow trout. These markers have great potential for use in marker-assisted selection (MAS) for IPN resistance and provide the basis for cloning of IPN resistance genes. Clarification of the genetic bases of complex traits has broad implications for fundamental research, but will also be of practical benefit to fish breeding.

Animals↗

PubMed2001

Genetic mapping of the dominant albino locus in rainbow trout (Oncorhynchus mykiss).

Albinism in animals is generally a recessive trait, but in Japan a dominant oculocutaneous albino (OCA) mutant strain has been isolated in rainbow trout (Oncorhyncus mykiss). After confirming that this trait is not due to a tyrosinase gene mutation that causes OCA1 (tyrosinase-negative OCA), we combined the amplified fragment length polymorphism (AFLP) technique with bulked segregant analysis (BSA) to map the gene involved in dominant oculocutaneous albinism. Four AFLP markers tightly linked to the dominant albino locus were identified. One of these markers was codominant and we have it converted into a GGAGT-repeat microsatellite marker, OmyD-AlbnTUF. Using this pentanucleotide-repeat DNA marker, the dominant albino locus has been mapped on linkage group G of a reference linkage map of rainbow trout. The markers identified here will facilitate cloning of the dominant albino gene in rainbow trout and contribute to a better understanding of tyrosinase-negative OCA in animals.

Albinism, Oculocutaneous↗

PubMed2001

Selective insolubility of alpha-synuclein in human Lewy body diseases is recapitulated in a transgenic mouse model.

alpha-Synuclein (alpha-SYN) is deposited in intraneuronal cytoplasmic inclusions (Lewy bodies, LBs) characteristic for Parkinson's disease (PD) and LB dementias. alpha-SYN forms LB-like fibrils in vitro, in contrast to its homologue beta-SYN. Here we have investigated the solubility of SYNs in human LB diseases and in transgenic mice expressing human wild-type and PD-associated mutant [A30P]alpha-SYN driven by the brain neuron-specific promoter, Thy1. Distinct alpha-SYN species were detected in the detergent-insoluble fractions from brains of patients with PD, dementia with LBs, and neurodegeneration with brain iron accumulation type 1 (formerly known as Hallervorden-Spatz disease). Using the same extraction method, detergent-insolubility of human alpha-SYN was observed in brains of transgenic mice. In contrast, neither endogenous mouse alpha-SYN nor beta-SYN were detected in detergent-insoluble fractions from transgenic mouse brains. The nonamyloidogenic beta-SYN was incapable of forming insoluble fibrils because amino acids 73 to 83 in the central region of alpha-SYN are absent in beta-SYN. In conclusion, the specific accumulation of detergent-insoluble alpha-SYN in transgenic mice recapitulates a pivotal feature of human LB diseases.

Amino Acids↗

PubMed2001

Improved fish lymphocyte culture for chromosome preparation.

Cytogenetic methodology is still underdeveloped in fishes compared with mammals. Culture condition for fish lymphocytes was optimized to improve chromosome preparation using the rainbow trout (Oncorhynchus mykiss) as a model after changing the combination of parameters such as mitogens, incubation periods, media, cell components, and freshness of blood. The optimized culture condition included isolation of lymphocytes from fresh blood by a stirring method, their culture in medium 199 supplemented with 10% FBS, 18 microg/ml of phytohemagglutinin (PHA-W) and 100 microg/ml of lipopolysaccharide (LPS) as mitogens, and harvested at 6 days after culture. This condition provided a notably increased mitotic index (MI) of 4.3-10.0% in rainbow trout lymphocytes. In addition, the condition was highly reproducible as shown by the similar level of MI in cultured lymphocytes from 181 individuals without failure. Applicability of this method in a wide range of fish groups was also proven with Ml of 1.1-13.3% in cultured lymphocytes from other 16 freshwater species of Acipenseridae, Anguillidae, Solmonidae, Cyprinidae, and Centrarchidae, and five marine species of Sparidae, Kyphosidae, Paralichthyidae, and Scorpaenidae. Chromosome preparations of improved quality by the present method were successfully applied for the replication R-banding with incorporation of 5-bromo-2'-deoxyuridine and direct R-banding fluorescence in situ hybridization.

Animals↗

PubMed2001

A case of submandibular malignant rhabdoid tumor transformed from papillary thyroid carcinoma.

Malignant rhabdoid tumor (MRT) in the neck region is very rare. We report a case of MRT in a 60-year-old woman who had a history of papillary carcinoma of the thyroid gland 7 years previously. One year before admission, in 1995, thyroid carcinoma recurred, and the tumor contained a small undifferentiated region with rhabdoid features. The tumor in 1996 consisted of round to oval rhabdoid cells with abundant cytoplasm, and the growth pattern was diffuse and infiltrative, with no papillary structures. We therefore concluded that the lesion was MRT, transformed from papillary thyroid carcinoma.

Aged↗

PubMed2001

Non-optically probing near-field microscopy with illumination of total internal reflection.

We have developed a non-optically probing near-field microscope with illumination of total internal reflection. Because the illumination light does not pass through the specimens, it is possible to observe thick specimens or highly absorptive materials. It reduces the background noise because the decay length of the evanescent wave is a few hundred nanometres. We found that although in the total internal reflection illumination system the light passed through the photosensitive film and illuminated the specimen, it did not affect the photosensitive film severely and did not limit the resolution. The imaging properties of reflection illumination and transmission illumination are analysed using a finite-differential time domain method.

Journal Article↗

PubMed2001

Liposomal prostaglandin E1 enhances optic nerve head blood flow in cats.

We investigated the effects of intravenous administration of prostaglandin E1 (PGE1) and lipo-prostaglandin E1 (lipo-PGE1), on optic nerve head blood flow (ONHBF) using ten anesthetized cats. Changes in relative ONHBF were noninvasively and continuously measured with fundus camera-based laser Doppler flowmetry. The blood pressure (BP) decreased significantly by 6 +/- 5 (mean +/- SD)% and 8 +/- 4%, respectively, after PGE1 (30, 100 ng/kg/min) administration, but at either of these concentrations there were no significant changes in ONHBF. On the other hand, with lipo-PGE1 (10 ng/kg/min), the BP remained unchanged, but ONHBF increased significantly by 61 +/- 49%. A larger dose of lipo-PGE1 (30 ng/kg/min) had opposite effects because the BP decreased significantly by 14 +/- 4% after administration, and the ONHBF remained unchanged (i.e., 67 +/- 102%). In all cases, there were no changes in IOP. With 10 ng lipo-PGE1, the large increase in ONHBF can be accounted for by vasodilation since perfusion pressure was unchanged. The inability of 30 ng lipo-PGE1 to affect ONHBF could be ascribed to the decrease in BP resulting in decreased ocular circulation. These results suggest that, in humans, lipo-PGE1 may also increase ONHBF provided that it is used at doses that do not produce large decreases in BP.

Alprostadil↗

PubMed2001

TIMP-1 promotes VEGF-induced neovascularization in the retina.

Proteolysis of vascular basement membranes and surrounding extracellular matrix is a critical early step in neovascularization. It requires alteration of the balance between matrix metalloproteinases (MMPs) and proteins that bind to and inactivate MMPs, tissue inhibitors of metalloproteinases (TIMPs). TIMP-1 has been demonstrated to inhibit neovascularization in chick chorioallantoic membranes. However, TIMP-1 has also been shown to either promote or inhibit cell proliferation and migration in different settings. To determine whether genetic alteration of the MMP/TIMP-1 ratio would alter retinal neovascularization, we crossed mice that express vascular endothelial growth factor (VEGF) in photoreceptors with TIMP-1-deficient mice or mice that overexpress TIMP-1. Compared to VEGF transgene-positive/TIMP-1-sufficient mice, VEGF transgene-positive/TIMP-1-deficient mice showed smaller neovascular lesions. There was also no difference between the two groups of mice in the appearance of the neovascularization by light or electron microscopy. Compound VEGF/TIMP-1 transgenic mice had increased expression of both VEGF and TIMP-1 in the retina, and had more neovascularization than mice that had increased expression of VEGF alone. These gain- and loss-of-function data suggest that alteration of the TIMP-1/MMP ratio modulates retinal neovascularization in a complex manner and not simply by altering the proteolytic activity and thereby invasiveness of endothelial cells.

Actins↗

PubMed2001

Validity and reliability of single-item questions about physical activity.

The Japan Collaborative Cohort Study for Evaluation of Cancer Risk Sponsored by Monbusho (JACC Study) included in its self-administered questionnaires some single-item questions concerning physical activity. We examined the validity of the questions among 1,730 Japanese adults and the reliability of the questions among 1,075 Japanese adults. The validity of the sports and physical exercise questions was estimated by comparing the self-administered questionnaire responses with the time spent on the activity and the energy expenditure index for the previous 12-month period, elicited by the interviewing method used in the Japan Lifestyle Monitoring Study with a minor modification. The Spearman's rank correlation coefficients ranged from 0.43 to 0.60, showing moderate correlations. On the other hand, test-retest reliability was estimated by comparing the responses from two separate surveys conducted roughly one year apart. Weighted kappa coefficients of sports and physical exercise questions, classified according to sex and age, ranged from 0.39 to 0.56, showing moderate reliability; and those of a question about walking ranged from 0.25 to 0.39, showing fair reliability. We suggest that measuring physical activity level with these single-item questions may be appropriate for establishing baseline data that reflects long-term physical activity in a large-scale cohort study targeting lifestyle-related diseases.

Adult↗

PubMed2001

Induction of specific cytotoxic T-cell activity against xenogeneic target cells in carp (Cyprinus carpio).

OBJECTIVE: To investigate the induction of cytotoxic T cells in carp (Cyprinus carpio) after inoculation of fish with 2 xenogeneic line cells and to examine specificity of the cytotoxic activity. ANIMALS: 22 carp. PROCEDURE: Fish were inoculated with mouse myeloma line cells P3.NS-1/1Ag4.1 (NS-1) or chicken Marek's disease tumor-derived lymphoma line cells (MDCC MSB-1). Cytotoxic activity of immune lymphocytes was evaluated by incubating effector cells with homologous and heterologous target cells. Populations of effector cells were identified by blocking T-lymphocytes from effector cells, using anti-carp T-cell monoclonal antibody and complement. RESULTS: Lymphocytes in blood, spleen, and head kidney of carp inoculated with NS-1 cells or MDCC MSB-1 cells had dose-dependent cytotoxic effects against homologous target cells but not against heterologous target cells. Lymphocytes from noninoculated carp did not have cytotoxic effects. Depletion of T-lymphocytes in spleen cells from NS-1-inoculated carp resulted in a decrease of cytotoxic activity against NS-1 cells. Cytotoxic activity of spleen lymphocytes from NS-1-inoculated or noninoculated carp was not evident when cytotoxic tests were performed after addition of anti-NS-1 carp serum. CONCLUSIONS AND CLINICAL RELEVANCE: Inoculation with xenogeneic target cells induces a specific cytotoxic T-cell response in carp. Thus, cell-mediated immunity plays a role in defense against infection of parasitic organisms such as protozoa and helminths.

Animals↗

PubMed2001

[The formation and involution of the optociliary vein during the course of central retinal vein occlusion].

BACKGROUND: Formation of collateral pathways by veins on the optic nerve head is sometimes observed during the resolution of a central retinal vein occlusion (CRVO). However, no cases have been reported which documented the formation and involution of these collateral pathways during the resolution of a CRVO. CASE: A 56-year-old man with a non-ischemic CRVO was followed over a 10-year period by ophthalmoscopy, fluorescein angiography (FA), and indocyanine green angiography (IA). Initial examination revealed only mild arteriosclerosis and absence of the optociliary vein (OCV) in the right eye. Approximately 9 years later, the patient returned with non-ishemic CRVO, and FA demonstrated a prolongation of the retinal circulation time to 12.1 seconds (normal < 11.0 seconds). Monitoring of this patient during treatment disclosed development of an OCV on the optic nerve head and gradual decrease in the retinal hemorrhage. In FA, the retinal circulation time was shortened and returned to normal. IA verified an outflow through the OCV into choroidal veins. Later, ophthalmoscopy showed a narrowing of the diameter of the OCV. CONCLUSION: We suggest that the OCV developed to drain blood from retinal veins to the vortex veins through choroidal veins to compensate for the slowing of retinal blood outflow. The reperfusion of the central retinal vein was accompanied by the narrowing of the OCV.

Collateral Circulation↗