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Biomedical subjects

A Oka

Publications and source records attributed to A Oka.

At least 19 recordsLinked to original sources

Identification of two new C4 alleles by DNA sequencing and evidence for a historical recombination of serologically defined C4A and C4B alleles.

Nucleotide polymorphisms of the C4 genes were investigated by direct sequencing of seven different homozygous typing cells from the 10IHW panels. Two novel sequences were identified within the C4d region of the C4 genes. Our sequencing analyses extend previous findings suggesting that a recombination hot spot is likely to have occurred between codon positions 1157 and 1186 within the C4d region. The classification of electrophoretically defined C4A and C4B alleles can be further subtyped by sequencing. Because the central major histocompatibility complex region that carries various copies of the C4 gene has been associated with a range of disorders; further analysis at the sequence level within the C4 locus may provide informative genetic markers for the investigation of disease-associated polymorphisms.

Alleles↗

Localization of a non-melanoma skin cancer susceptibility region within the major histocompatibility complex by association analysis using microsatellite markers.

The major histocompatibility complex (MHC) is known to have a role in the development of non-melanoma skin cancer (NMSC), although the genes and mechanisms involved have yet to be determined. To identify the susceptibility locus for NMSC within the MHC, we used a collection of well-defined polymorphic microsatellite markers from the Human leucocyte antigen (HLA) region for an association analysis of 150 cases with NMSC and 200 healthy controls selected from the Busselton population in Western Australia. High-resolution mapping was undertaken using a total of 40 highly polymorphic markers located at regular intervals across the HLA region (3.6Mb). Polymerase chain reaction (PCR) analysis was initially performed on pooled DNA markers to detect those markers that showed different allele profiles. Statistically significant differences in allelic frequencies (differentiating alleles) were found between cases and controls at three polymorphic microsatellite loci within a 470-kb genomic susceptibility region ranging between 6 kb centromeric of the HLA-B gene and intron 5 of the DDR gene. Interestingly, this genome region corresponded completely with the psoriasis-susceptibility locus. The three differentiating alleles and another four markers outside the susceptibility region were then PCR tested by individual genotyping of cases and controls. The newly identified susceptibility locus for NMSC within the MHC was found to be significantly different between the cases and controls by comparisons of allele frequencies at the three differentiating loci estimated from DNA pools and then confirmed by individual genotyping. This is the first study using high density microsatellite markers to localize a NMSC susceptibility region within the human genome.

Australia↗

Corneodesmosin gene: no evidence for PSORS 1 gene in North-eastern Thai psoriasis patients.

Psoriasis vulgaris, a common inflammatory skin disorder, is known to be associated with the HLA-Cw*06 allele. It has been recently suggested by microsatellite mapping that a real susceptible gene for psoriasis resides in the approximately 100-kb genomic region telomeric of the HLA-C gene. In this respect, the corneodesmosin (CDSN) gene 160-kb telomeric of HLA-C is a strong candidate because of its location and its functional role in corneocyte cohesion and desquamation. In fact, a significant association between CDSN polymorphism and psoriasis was recently recognized in Caucasian populations. However, this association has not been replicated in other studies, being still controversial. In this study, we investigated the genetic polymorphism of the CDSN gene in 139 psoriasis patients and 144 healthy controls in the North-eastern Thai population. By direct sequencing technique, a total of 28 polymorphic sites were found, consisting of 26 single nucleotide polymorphisms (SNPs) and two indels (insertion/deletion). Among them, six SNPs have not been previously reported. Through this analysis, as many as 28 different SNP/indel haplotypes within the CDSN gene were identified. Seven SNPs and one indel, namely 9C, 614 A, 722T, 971T, 1215G, 1243C, 1331G and 1606AAG (deletion), revealed significant deviation in the allelic frequencies of the patients from those of the healthy controls. However, none of them are likely to be responsible for controlling the susceptibility of psoriasis, but these associations can be explained by a linkage disequilibrium to a real pathogenic allele of a nearby gene. Further, the large variations between the CDSN SNP/indel haplotypes and the psoriatic major histocompatibility complex (MHC) haplotypes also make it unlikely that CDSN is a major psoriasis-susceptible gene.

Gene Frequency↗

Vertebral artery dissection in an infant: ultrastructural aberrations in connective tissue components.

We report on a 14-month-old boy who had acute multiple infarcts in the posterior circulation due to an extremely early onset of spontaneous vertebral artery dissection. Despite the absence of clinical signs of connective tissue disorders, an ultrastructural change of collagen fibrils and elastic fibers indicated connective tissue abnormalities. Arterial dissection should be considered as a cause of stroke during infancy.

Elastic Tissue↗

Susceptibility locus for non-obstructive azoospermia is localized within the HLA-DR/DQ subregion: primary role of DQB1*0604.

Non-obstructive azoospermia is a male infertility characterized by no or little sperm in semen as a result of a congenital dysfunction in spermatogenesis. Previous studies have reported a higher prevalence of particular human leukocyte antigen (HLA) antigens in non-obstructive azoospermia. As the expression of the RING3 gene located in the HLA class II region was predominant in the testis, mainly around spermatids and pachytene spermatocytes, it is tempting to speculate that RING3 is one of the strong candidate genes responsible for the pathogenesis of the disease. In this study, the genetic polymorphism in the RING3 gene was investigated by the direct sequencing technique. As a result, a total of 14 single nucleotide polymorphisms were identified. Among them, six were localized in the coding region but none of them was accompanied by an amino-acid substitution. No significant difference in the allelic distribution at these 14 polymorphic sites was observed between the patients and healthy controls, suggesting that the susceptible gene for non-obstructive azoospermia is not the RING3 gene. Then, in order to map the susceptibility locus for non-obstructive azoospermia precisely within the HLA region, 11 polymorphic microsatellite markers distributed from the SACM2L gene just outside the HLA class II region (187 kb telomeric of the DPB1 gene) to the OTF3 gene in the HLA class I region were subjected to association analysis in the patients. Statistical analysis of distribution in the allelic frequency at each microsatellite locus demonstrated that the pathogenic gene for non-obstructive azoospermia is located within the HLA-DR/DQ subregion. In fact, DRB1*1302 and DQB1*0604 were found to be strongly associated with non-obstructive azoospermia by polymerase chain reaction-based DNA typing. Further, haplotype analysis suggested that the DQB1*0604 allele may play a decisive role in the pathogenesis of non-obstructive azoospermia.

Alleles↗

Corneodesmosin DNA polymorphisms in MHC haplotypes and Japanese patients with psoriasis.

In order to examine the relationship between corneodesmosin (CDSN) and psoriasis we have determined the presence of CDSN polymorphisms by DNA sequencing in (a) nine B-LCL cell lines of major histocompatibility complex ancestral haplotypes known to be associated with psoriasis vulgaris including 13.1AH, 46.1AH, 46.2 and 57.1AH, and in (b) a group of 267 unrelated individuals comprising Japanese psoriasis patients (n = 101) and Japanese subjects without the disease (n = 166). Three novel CDSN gene sequences were identified. In addition, we have classified the 18 alleles into seven main groups based on phylogeny of non-synonymous substitutions. However, we have found no statistically significant differences between the patients and the unaffected individuals in any of these groups. These findings indicate that CDSN is not a major psoriasis susceptibility gene.

Alleles↗

Genetic effects on fatty acid composition of carcass fat of Japanese Black Wagyu steers.

Two hundred ninety-three Japanese Black Wagyu steers derived from 34 sires were used to investigate genetic effects on the fatty acid composition of carcass fat. All steers were fed identical diets for 365 d and slaughtered at similar ages. If the percentage of genetic contribution of sire A, B, or C was not lower than 25%, steers were classified into groups A, B, and C, respectively. Fatty acid compositions differed depending on deposit sites. Mean percentage of monounsaturated fatty acids (MUFA) tended to be higher in the outer parts than in the inner parts of the body. Percentage of MUFA in carcass fat was negatively correlated with withers height and BW and positively correlated with meat quality score and marbling score. Fatty acid compositions of the 34 sire groups varied, and mean percentages of MUFA in i.m. fat ranged from 47.71 to 54.77%. Steers in the C group grew larger than those in the A or B group. Mean percentages of MUFA for i.m. fat in the A, B, and C groups (52.83, 51.88, and 50.33%, respectively) differed (P < 0.05) from each other. Steers in the C group had higher (P < 0.05) percentages of saturated fatty acids than those in the A or B groups. Percentages of genetic contribution of sires B (P < 0.05) and C (P < 0.001) were negatively correlated with percentage of MUFA in i.m. fat. These results suggested that genetic factors affected fatty acid composition of carcass fat in Japanese Black Wagyu cattle and that some sires had potent genetic factors affecting this composition.

Adipose Tissue↗

ARR1, a transcription factor for genes immediately responsive to cytokinins.

Cytokinins are a class of phytohormones involved in various physiological events of plants. The Arabidopsis sensor histidine kinase CRE1 was recently reported to be a cytokinin receptor. We used a steroid-inducible system to show that the transcription factor-type response regulator ARR1 directs transcriptional activation of the ARR6 gene, which responds to cytokinins without de novo protein synthesis. This fact, together with characteristics of ARR1-overexpressing plants and arr1 mutant plants, indicates that the phosphorelay to ARR1, probably from CRE1, constitutes an intracellular signal transduction occurring immediately after cytokinin perception.

Adenine↗

Distribution and development of CLN2 protein, the late-infantile neuronal ceroid lipofuscinosis gene product.

Expression of the late-infantile neuronal ceroid lipofuscinosis (LINCL) gene (CLN2) protein was investigated by immunoblotting and immunohistochemistry in human brains and visceral organs of control individuals and of patients with neuronal ceroid lipofuscinosis (NCL). Immunoblotting analyses showed reactivity in the cerebrum, liver, kidney, heart and colon of controls, whereas CLN2 protein was not detected in these organs in a LINCL patient. Immunohistochemistry showed that the reactivity of the protein was ubiquitous in extracerebral organs as well as within the CNS, apparently corresponding to widely distributed deposition of lipopigments in LINCL. The expression of CLN2 protein in the cerebral cortex increased with development, and reached adult level after the age of 2. This development of expression seemed to be related to the onset of LINCL at 2-4 years of age. We confirmed no immunoreactivity in two of three patients with LINCL, who were diagnosed clinicopathologically. One case showing combined ultrastructural morphology of fingerprint profiles and curvilinear bodies had intermediate reactivity, suggesting heterogeneity in clinical LINCL. Evaluation of the immunoreactivity of the CLN2 protein may be useful for characterization of a variant form.

Adolescent↗

A Japanese girl with leukoencephalopathy with vanishing white matter.

A Japanese girl with peculiar leukoencephalopathy was reported. Following normal development until 1 year of age, she showed progressive neurological deterioration with ataxia, epilepsy, pyramidal tract signs and choreic movement. Serial brain computed tomographies (CTs) revealed markedly low density and progressive volume loss in whole white matter. In extensive laboratory investigations, the level of glycine in the urine was elevated. She died at the age of 4 years, and the neuropathological findings were comprised of severe extensive changes in cerebral and cerebellar white matter, such as marked rarefaction or cystic degeneration with axonal loss. The pontine central tegmental tracts were also affected. Neuronal loss was seen in the cerebellar cortex. These features were compatible with leukoencephalopathy with vanishing white matter, which was recently established as a clinical entity. To our knowledge, this is the first report of a non-Caucasian patient with this new type of leukoencephalopathy.

Brain↗

An upstream region of the Arabidopsis thaliana CDKA;1 (CDC2aAt) gene directs transcription during trichome development.

The cell cycle of eukaryotes is tightly regulated through the activity of cyclin-dependent kinases. The Arabidopsis thaliana CDKA;1 (CDC2aAt) gene is thought to encode such a protein kinase, since it is actively transcribed in proliferating tissues and can complement defects in the Schizosaccharomyces pombe cdc2 gene. We analyzed the functional structure of the CDKA;1 promoter, using fusion genes between various upstream regions of CDKA;1 and the Escherichia coli beta-glucuronidase (GUS) gene. A 595 bp DNA fragment upstream from the transcription start site conferred GUS activity on developing trichomes, but not on proliferating tissues. On the other hand, another upstream fragment extending to the 5' non-coding transcribed region gave GUS activity to both proliferating tissues and developing trichomes. Against the gl2 mutant background, GUS activity directed by the 595 bp fragment was detected in single-stalk cells, but not in giant cells without obvious polar extension growth. These results revealed that the 595 bp fragment lacks cis element(s) essential for proliferating-cell-specific promoter activity, but can direct transcription in a specific period during trichome development, which does not include cell division. This suggests that CDKA;1 functions during cell morphogenesis as well as cell proliferation.

Arabidopsis↗

New polymorphic microsatellite markers in the human MHC class III region.

The human major histocompatibility complex (MHC) class III region spanning approximately 760 kb is characterized by a remarkably high gene density with 59 expressed genes (one gene every 12.9 kb). Recently, susceptibility loci to numerous diseases, such as Graves disease, Crohn disease, and SLE have been suggested to be localized to this region, as assessed by associations mainly with genetic polymorphisms of TNF and TNF-linked microsatellite loci. However, it has been difficult to precisely localize these susceptibility loci to a single gene due to a paucity to date of polymorphic markers in the HLA class III region. To facilitate disease mapping within this region, we have analyzed 2 approximately 5 bases short tandem repeats (microsatellites) in this region. A total of 297 microsatellites were identified from the genomic sequence, consisting of 69 di-, 62 tri-, 107 tetra-, and 59 penta-nucleotide repeats. It was noted that among them as many as 17 microsatellites were located within the coding sequence of expressed genes (NOTCH4, PBX2, RAGE, G16, LPAAT, PPT2, TNXB, P450-CYP21B, G9a, HSP70-2, HSP70-1, HSP-hom, MuTSH5 and BAT2). Eight microsatellite repeats were collected as polymorphic markers due to their high number of alleles (11.9 on average) as well as their high polymorphic content value (PIC) (0.63). By combining the 38 and the 22 polymorphic microsatellites we have previously collected in the HLA class I and class II regions, respectively, we have now established a total of 68 novel genetic markers which are uniformly interspersed with a high density of one every 63.3 kb throughout the HLA region. This collection of polymorphic microsatellites will enable us to search for the location of any disease susceptible loci within the HLA region by association analysis.

Chromosome Mapping↗

Negative autoregulation of the Arabidopsis homeobox gene ATHB-2.

The Arabidopsis homeobox gene ATHB-2 is tightly regulated by light signals, and is thought to direct morphological changes during shade avoidance responses. To understand how ATHB-2 mediates light signals in plant morphogenesis, we investigated its transcriptional network. We constructed a gene encoding a chimeric transcription factor (HD-Zip-2-V-G) that is expected to activate target genes of ATHB-2 in a glucocorticoid-dependent manner. In transgenic Arabidopsis plants expressing HD-Zip-2-V-G, glucocorticoid treatment activates the ATHB-2 gene itself, independent of de novo protein synthesis. An in vitro DNase I-footprinting experiment showed that recombinant ATHB-2 protein specifically bound to an ATHB-2 promoter region. These complementary results indicate that ATHB-2 recognizes its own promoter. Consistent with the fact that ATHB-2 itself has been shown to act as a repressor, expression of the endogenous ATHB-2 gene was repressed in transgenic plants overexpressing an ATHB-2 transgene. Moreover, target-gene analysis using the HD-Zip-2-V-G suggested that ATHB-2 recognizes other HD-Zip II subfamily genes. We conclude that ATHB-2 has a negative autoregulatory loop and may be involved in a complicated transcriptional network involving paralogous genes, as is the case with animal homeobox genes.

Arabidopsis↗

Type I Helicobacter pylori lipopolysaccharide stimulates toll-like receptor 4 and activates mitogen oxidase 1 in gastric pit cells.

Guinea pig gastric pit cells express an isozyme of gp91-phox, mitogen oxidase 1 (Mox1), and essential components for the phagocyte NADPH oxidase (p67-, p47-, p40-, and p22-phox). Helicobacter pylori lipopolysaccharide (LPS) and Escherichia coli LPS have been shown to function as potent activators for the Mox1 oxidase. These cells spontaneously secreted about 10 nmol of superoxide anion (O(2)(-))/mg of protein/h under LPS-free conditions. They expressed the mRNA and protein of Toll-like receptor 4 (TLR4) but not those of TLR2. LPS from type I H. pylori at 2.1 endotoxin units/ml or higher stimulated TLR4-mediated phosphorylations of transforming growth factor beta-activated kinase 1 and its binding protein 1 induced TLR4 and p67-phox and up-regulated O(2)(-) production 10-fold. In contrast, none of these events occurred with H. pylori LPS from complete or partial deletion mutants of the cag pathogenicity island. Lipid A was confirmed to be a bioactive component for the priming effects, while removal of bisphosphates from lipid A completely eliminated the effects, suggesting the importance of the phosphorylation pattern besides the acylation pattern for the bioactivity. H. pylori LPS is generally accepted as having low toxicity; however, our results suggest that type I H. pylori lipid A may be a potent stimulator for innate immune responses of gastric mucosa by stimulating the TLR4 cascade and Mox1 oxidase in pit cells.

Adaptor Proteins, Signal Transducing↗

Helicobacter pylori lipopolysaccharide induces apoptosis of cultured guinea pig gastric mucosal cells.

Helicobacter pylori lipopolysaccharide (LPS) is generally accepted as a low-toxicity virulence. Primary cultures of guinea pig gastric mucosal cells expressed the Toll-like receptor 4 and were sensitive to H. pylori LPS as well as Escherichia coli LPS. H. pylori LPS stimulated phosphorylation of transforming growth factor-beta-activated kinase 1 (TAK1), TAK1-binding protein 1 (TAB1), and c-Jun NH(2)-terminal kinase (JNK) 2. H. pylori LPS at >2.1 endotoxin unit/ml (>1 ng/ml) activated caspase-8, stimulated cytochrome c release from mitochondria, and subsequently activated caspases-9 and -3, leading to apoptosis. Epidermal growth factor blocked all of these apoptotic processes and inhibited apoptosis, whereas it did not modify the phosphorylation of TAK1, TAB1, and JNK2. A comparatively specific inhibitor of caspase-8 or -9 blocked apoptosis, whereas cytochrome c release was prevented only with a caspase-8-like inhibitor. Our results suggest that caspase-8 and mitochondria may play crucial roles in H. pylori LPS-induced apoptosis and that this accelerated apoptosis may be involved in abnormal cell turnover of H. pylori-infected gastric mucosa.

Animals↗

Relaxing and contracting activities of heartworm extract on isolated canine abdominal aorta.

Effect of adult heartworm (HW) crude extract on isolated canine abdominal aortic strips precontracted with noradrenaline was examined by recording isometric changes in tension. HW extract caused contraction of the aortic strip at a low concentration (LC) and its relaxation at a high concentration (HC). In aortic strips without endothelium, LC extract elicited a contraction similar to that in the strips with endothelium, whereas HC extract failed to produce any relaxation but instead produced a contraction. The relaxing effect of HC extract was blocked after treatment with 300 microM NG-nitro-L-arginine methyl ester hydrochloride, with reversal by additional treatment with 3 mM L-arginine. It was also markedly reduced or abolished after treatment with 3 microM oxyhemoglobin or 1 microM methylene blue. Fractionation of HW extract by high-performance liquid chromatography revealed that the relaxing and contracting activities are due to different substances in the extract. The results indicate that HW extract contains 2 different vasoactive substances, 1 causing contraction of canine abdominal aorta via a direct action on the smooth muscle, and the other its relaxation indirectly by releasing nitric oxide from endothelial cells. These vasoactive substances might play a role in HW extract-induced shock in dogs, and in the pathogenesis of HW infection.

Animals↗