Search PubMed⌕ Search

Biomedical subjects

K Tokunaga

Publications and source records attributed to K Tokunaga.

At least 199 records · Page 11Linked to original sources
PubMed1997

YAC and cosmid contigs encompassing the Fukuyama-type congenital muscular dystrophy (FCMD) candidate region on 9q31.

Fukuyama-type congenital muscular dystrophy (FCMD), the second most common form of childhood muscular dystrophy in Japan, is an autosomal recessive severe muscular dystrophy associated with an anomaly of the brain. We had mapped the FCMD gene to an approximately 5-cM interval between D9S127 and D9S2111 on 9q31-q33 and had also found evidence for linkage disequilibrium between FCMD and D9S306 in this candidate region. Through further analysis, we have defined another marker, D9S172, which showed stronger linkage disequilibrium than D9S306. A yeast artificial chromosome (YAC) contig spanning 3,5 Mb, which includes this D9S306-D9S172 interval on 9q31, has been constructed by a combination of sequence-tagged site, Alu-PCR, and restriction mapping. Also, cosmid clones subcloned from the YAC were assembled into three contigs, one of which contains D9S2107, which showed the strongest linkage disequilibrium with FCMD. These contigs also allowed us to order the markers as follows: cen-D9S127-(approximately 800 kb)-D9S306 (identical to D9S53)-(approximately 700 kb)-A107XF9-(approximately 500 kb)-D9S172-(approximately 30 kb)-D9S299 (identical to D9S774)-(approximately 120 kb)-WI2269-tel. Thus, we have constructed the first high-resolution physical map of the FCMD candidate region. The YAC and cosmid contigs established here will be a crucial resource for identification of the FCMD gene and other genes in this region.

Chromosomes, Artificial, Yeast↗
PubMed1997

Large-scale comparative mapping of the MHC class I region of predominant haplotypes in Japanese.

In order to further our understanding of major histocompatibility complex (MHC) class I gene organization, we began a comparative analysis of the large scale organization of the class I region in diverse haplotypes. For these studies, the MHC in healthy Japanese donors who have the predominant MHC haplotypes and/or HLA-A or -B alleles was examined by pulsed field gel electrophoresis and Southern analysis using probes spanning the class I region. Hybridization with probes from the HLA-A to HLA-G region revealed that individuals expressing HLA-A30, -A31, or -A33 have an approximately 70 kilobase (kb) insertion near the HLA-A gene as compared with haplotypes containing the HLA-A11 or -A26 allele. Conversely, HLA-A24-containing haplotypes appear to have an approximately 50 kb deletion from the same region. Further, it appears that chromosomes carrying closely related alleles are similar to each other in this region, consistent with their presumed evolutionary relationship. While little is known about the gene content between the HLA-A and HLA-G region, it will be interesting to examine the prospect that functional genes do in fact reside within the inserted or deleted portions, thereby raising the possibility that distinct functional differences are conferred by different haplotypes. Overall, the results reported here should contribute to furthering our understanding of the association between diseases and HLA as well as provide new insights into the evolution of the MHC.

Alleles↗
PubMed1997

Sequence-based association analysis of HLA class I and II alleles in Japanese supports conservation of common haplotypes.

Alleles of HLA-A, B, C, DRB1, DQB1, and DPB1 loci were fully determined in 117 healthy Japanese. A*2402, A*3303, A*1101, A*0201, B*4403, B*5201, Cw*0102, Cw*1403, Cw*0304, Cw*0702, Cw*0801, and Cw*1202 showed frequencies of over 10%. Multi-locus haplotype frequencies were estimated by the maximum likelihood method. Strength of association between C and B loci was comparable with that between DRB1 and DQB1 loci. Alleles unidentified by a serological method and having very similar nucleotide sequences (A2: A*0201, A*0206, A*0207, B61: B*4002, B*4006) were carried by different haplotypes. Several frequent five-locus haplotypes were identified including A*3303-Cw*1403-B*4403-DRB1(*)1302-DQB1(*)0604, and A*2402-Cw*1202-B*5201-DRB1(*)1502-DQB1(*)0601. These sequence-based haplotypes corresponded to serology-based common haplotypes which have already been described in Japanese. These findings indicate that common HLA haplotypes consist of particular sets of HLA alleles and that these haplotypes have been conserved through recent human evolution.

Alleles↗
PubMed1997

Growth ability of auxiliary gene mutants of human immunodeficiency virus types 1 and 2 in unstimulated peripheral blood mononuclear cells.

Mutational studies on the Vif, Vpr, Vpu, Vpx, and Nef genes of human immunodeficiency virus types 1 and 2 (HIV-1 and HIV-2) were performed to evaluate their biological functions in natural target cells. For this purpose, replication properties of mutant viruses derived from HIV-1 NL strain and HIV-2 GH strain in unstimulated peripheral blood mononuclear cells were determined. Vif- viruses of both HIV-1 and HIV-2 did not grow at all in these cells. Similarly, no replication of HIV-2 Vpx- mutant was detected. In contrast, both of Vpr- and Nef- viruses of HIV-1 and HIV-2, and Vpu- virus of HIV-1 grew quite well in the cells. These results show, together with the data previously reported, that only Vif and Vpx are essential for HIV replication in primary blood cell cultures.

Cells, Cultured↗
PubMed1997

Increased serum remnant lipoproteins in patients with apolipoprotein E7 (apo E Suita).

Apolipoprotein (apo) E7 was originally identified by Yamamura et al. in subjects with atherosclerotic cardiovascular diseases (J. Clin. Invest. 1984;74:1229). However, the lipoprotein abnormalities associated with apo E7 phenotype have not been elucidated. In the current study, to clarify the physiological roles of apo E7, lipoprotein abnormalities were studied in 12 apo E7 heterozygotes. A total of seven subjects were hyperlipidemic and five subjects were normolipidemic. The apo E phenotype was apo E7/3 in 11 subjects and apo E7/4 in one subject. Polymerase chain reaction revealed that all of the subjects with apo E7 phenotype had the same mutation as that of apo E(Suita) as reported previously (J. Biochem. 1989;105:249). All the hyperlipidemic subjects were over 40 years of age and two of them also had and severe coronary heart disease. Ultracentrifugal analysis revealed that the cholesterol level both in very low density lipoprotein and in intermediate density lipoprotein (IDL) was substantially higher in hyperlipidemic apo E7 heterozygotes, compared with control subjects and that the IDL cholesterol was also increased even in normolipidemic apo E7 heterozygotes. Polyacrylamide gel electrophoresis of lipoproteins showed a midband, which implies the increase of remnant lipoproteins, in 11 subjects out of 12, irrespective of the presence or absence of hyperlipoproteinemia. In two cases, a broad beta pattern was observed similar to that seen in type III hyperlipoproteinemia. Dietary therapy was dramatically effective for the treatment of hyperlipidemia in patients with apo E7. These findings confirm that apo E is crucial for remnant lipoprotein metabolism and that apo E7 is related to the increase in serum remnant lipoproteins, which leads to hyperlipoproteinemia in association with obesity, aging and impaired glucose metabolism.

Adult↗
PubMed1997

Early morphologic changes of atherosclerosis induced by ventromedial hypothalamic lesion in the spontaneously diabetic Goto-Kakizaki rat.

It is generally thought that typical atherosclerotic lesions do not develop in the rodent. The Goto-Kakizaki (GK) rat is a nonobese strain in which a spontaneous type of non-insulin-dependent diabetes mellitus develops without apparent macroangiopathy. In our previous study, making ventromedial hypothalamic (VMH) lesions in GK rats induced hyperphagia and a further deterioration in glucose metabolism. In the current study, male GK rats in which VMH lesions were made were examined for vascular changes, with special reference to atherosclerotic lesions. Marked hyperglycemia in GK rats with VMH lesions (hereafter referred to as VMH lesion rats) was revealed over an observation period (plasma glucose levels 16 weeks after the operation: VMH lesion GK rats, 19.3 +/- 2.0 mmol/L, vs sham-operated GK rats, 10.1 +/- 1.3 mmol/L; p < 0.0001). Light microscopic observation of the descending aorta in VMH lesion GK rats 16 weeks after the surgery revealed that the intimal thickening and the number of infiltrating cells into the intima were significantly increased as compared with sham-operated GK rats (17531 +/- 3747 microm2 vs 3072 +/- 1192 microm2, p < 0.0001; 15.6 +/- 3.1 per one transverse section vs 6.8 +/- 2.5 per one transverse section, p < 0.0005). Electron microscopic observations demonstrated an increased number of microvilli and lysosomes in endothelial cells, infiltration of macrophages and lymphocytes into the intima, and migration of medial smooth muscle cells into the intima that are considered to be early events in atherosclerosis. These morphologic changes could be induced by a deterioration in glucose metabolism. This rat may thus be useful for studying the process of the initiation of atherosclerosis in diabetes mellitus.

Animals↗
PubMed1997

Japanese population does not manifest significant association between low NK activity and HLA-B(C) locus homozygosity.

It was reported previously that natural killer (NK) activity is controlled by the HLA-B(C) region and that individuals homozygous for HLA-B(C) or homozygous for the NKB complementation groups, which are mapped to the HLA-B(C) region, have fewer circulating NK cells and lower NK activity than do individuals heterozygous for these alleles. Those studies had used subjects in the United States. In the present study, we investigated the NK activity, NK subpopulation, and HLA types of 65 healthy Japanese individuals in Japan, most of whom have a quite different HLA-B(C) type than did subjects in the earlier study. Among 13 individuals having low NK activity, only two were HLA-B(C) homozygous and the rest were heterozygous. No obvious relation between low NK activity and specific HLA-B(C) allele was found. Seven of the nine HLA-B(C) homozygotes had medium or high NK activity. No significant differences were detected in either the NK activity or in the NK subset frequencies (circulating NK cell number) between HLA-B(C) homozygous and heterozygous individuals. These results indicate that HLA-B(C) homozygosity does not always induce low NK activity and that other factors also may influence NK activities.

Adult↗
PubMed1997

Modulation of apolipoprotein gene expression in fatty liver of obese rats: enhanced APOA-IV, but no APOB expression by a high sucrose diet.

OBJECTIVE: Hepatic lipoprotein production is important to the understanding of mechanisms involved in the development of fatty liver and hyperlipidemia. Previously, we have reported that hepatic fatty acid synthesis and apolipoproteinB transcription are increased in obese rats. Here, we describe the effects of a high sucrose diet on hepatic fatty acid synthesis and apolipoprotein gene expression in obese rats. DESIGN: Obese rats with ventromedial hypothalamic lesions were fed on a high sucrose diet (30.3% of cal) or lab chow for 11 weeks. RESULTS: Serum triglycerides and plasma immuno-reactive insulin concentrations were further increased in the obese rats fed a high sucrose diet. The experimental diet increased the activity of hepatic acetyl-CoA carboxylase, the rate limiting enzyme for hepatic fatty acid synthesis, and triglycerides content, concurrent with an increase abundance of apolipoproteinA-IC mRNA in the obese rats. Despite further accumulation of hepatic triglycerides there was no further increase in hepatic apolipoproteinB mRNA abundance in the obese rats fed the high sucrose diet. CONCLUSION: These data suggest that the synthesis of hepatic fatty acids but not of apolipoproteinB is further increased in obese rats fed the high sucrose diet, and that apolipoproteinA-IV gene expression may be modulated in response to alterations in hepatic triglycerides flux.

Acetyl-CoA Carboxylase↗
PubMed1997

Two decades of annual medical examinations in Japanese obese children: do obese children grow into obese adults?

OBJECTIVE: To investigate trends in frequency of obese children in Japan over two decades, the frequency of obese children who grow into obese adults and predictive factors for adult obesity. DESIGN: Annual cross-sectional studies for 22 y (1974-1995) with a follow-up study. SUBJECTS: Cross-sectional: Cumulatively 13,186 obese (% of standard body weight (SBW): > or = 120%) schoolchildren including 3158 extremely obese (> or = 140% of SBW) children out of 203,088 schoolchildren (age: 6-14 y) in Izumiohtsu City, Osaka, Japan. FOLLOW-UP: 151 initially obese children (initial age: 6-14 y and age at follow-up: 20-35 y) who lived in Izumiohtsu City. CONTROL: 3552 Japanese men and 4631 Japanese women (age: 20-35 y). MEASUREMENTS: Cross-sectional: height, weight, trunk circumference, skin-fold thickness, blood pressure and blood biochemicals. FOLLOW-UP: height, weight, trunk circumference, skin-fold thickness during childhood, and body height and weight at follow-up. Adulthood obesity: > or = 120% of the average body mass indices (BMI) of the controls. RESULTS: Frequency of obese children increased from 5% to more than 10%, and that of extremely obese children increased from 1% to more than 2% during these 22 y. These increases were most prominent in the schoolboys aged 9-11 y. Prevalence of hyperglycemia and hyperlipidemia in the extremely obese children did not change, and that of hypertension and abnormal liver function gradually decreased during these two decades. After coming of age, 32.2% of the initially obese boys (relative risk: 5.3) and 41.0% of the initially obese girls (relative risk: 6.7) remained obese. BMI, percentage of the SBW and skin-fold thickness at the biceps during childhood were significantly larger in currently-obese girls. Positive correlations were demonstrated between these variables and percentage SBW at follow-up. CONCLUSIONS: Childhood obesity is increasing in Japan, especially in boys aged 9-11 y. Approximately 32% of the obese boys and 41% of the obese girls grow into obese adults, and the degree of obesity is a predictive factor for adult obesity.

Adolescent↗
PubMed1997

Identification of HLA-C alleles using PCR-single-strand-conformation polymorphism and direct sequencing.

Alleles encoding HLA-C antigens in Japanese were identified by polymerase chain reaction followed by single strand conformation polymorphism (PCR-SSCP) and nucleotide sequencing analyses. The results showed that at least sixteen different alleles code for eight serologically detectable antigen groups and undetectable blanks. Cw1 was mainly encoded by Cw*0102, whereas two split antigens of Cw3, Cw9 and Cw10, were encoded by Cw*0303 and Cw*0304, respectively. Cw4 and Cw6 were encoded by Cw*0401 and Cw*0602, respectively. Seven alleles, Cw*0801, Cw*0803, Cw*1202, Cw*1203, Cw*1402, Cw*1403 and Cw*1502, were found to encode serological HLA-C "blanks" in Japanese. Moreover, errors in the published nucleotide sequences of Cw*0501 and Cw*1201 were corrected. Twenty-one HLA-C alleles were distinguished from each other by means of group-specific PCR amplification followed by the SSCP method developed in the present study. The system using genomic DNAs can be used effectively for identification of new HLA-C alleles.

Alleles↗
PubMed1997

Five HLA-B22 group alleles in Japanese.

HLA-B22-group alleles in Japanese were identified using PCR-single-strand conformation polymorphism (SSCP) and sequence analyses. We analyzed genomic DNAs obtained from Japanese individuals positive for HLA-B22 group antigens (HLA-B54, B55, B56) including two locally proposed splits (B55.2, and B22N). In the SSCP analysis of both exons 2 and 3, we discriminated five different B22-group alleles. Each allelic pattern corresponded to each serological split antigen. Direct sequencing analysis of exon 2 and exon 3 showed that alleles encoding B54, B55.1 and B56 antigens in Japanese are encoded by B*5401, B*5502 and B*5601, respectively, and those encoding B55.2 and B22N antigens are previously unidentified alleles, B*5504 and B*5603, respectively. Full-length cDNA sequencing showed that the B*5603 sequence is identical to those of B*5501, B*5502, B*5601, and B*5602 in exons 1 to 2 except for a synonymous substitution at nucleotide position 165 in exon 2. On the other hand, the sequence of exons 3 to 7 was identical to those of some B15 and B46 alleles, suggesting that B*5603 was generated by a recombination event between one of the B55 and B56 alleles and one of the B15 and B46 alleles in intron 2. As for B*5504, the entire exon 1 to 7 sequence is identical to that of B*5502 except that the 5'-half of the exon 3 sequence is identical to those of some B7, B27, B40 and B48 alleles, suggesting that an event such as gene conversion, segmental exchange, or double recombination occurred in this region.

Alleles↗
PubMed1997

The HLA system in the population of Mongolia.

The frequencies of HLA-A, B, C and DRB1 alleles and haplotype frequencies for HLA-A, B, C and A, B, DR loci were studied in 201 healthy unrelated Khalkha-Mongolians. The most common class I antigens were A24 (25.8%), A2 (23.4%), B61 (12.6%), B51 (8.5%), Cw10 (14.2%), Cw9 (14.1%), Cw7 (13.3%), Cw1 (11.8%) and Cw6 (10.2%). A total of 35 DRB1 alleles were identified in this group of samples. The most frequent DRB1 allele was DRB1*0301 (11.1%), followed by DRB1*0701 (9.7%) and DRB1*1101 (8.5%). One novel DRB1 allele (14MV) and three rare types, DRB1*1111, DRB1*1504 and DRB1*1412, recently described in Jews, the Dai minority of China and Japanese, respectively, were identified in Mongolians. The phylogenetic tree constructed by UPG method put Mongolians in the Northeast Asian cluster. A comparison of three locus haplotype distributions with world populations, revealed that Mongolians share several characteristics in common with other Mongoloids as well as with Caucasoids and Amerindians. The most common A, B and DR haplotype in Mongolians, A33-B58-DR3, was shared with Thai, Thai Chinese and Singapore Chinese. These data support that unique genetic background of Mongolians played a major role in ethnic formation and differentiation of Mongoloid populations.

Alleles↗
PubMed1997

An HLA-B null allele (B*1526N) with a stop codon in exon 3 generated by a point mutation.

An HLA-B null allele was identified in a Japanese family during histocompatibility testing for bone marrow transplantation. The propositus was a healthy Japanese woman with three children, and her parents were cousins. Serological HLA typing of the family members indicated that the propositus was homozygous for the A24-Cw4-B blank (B null)-DR4.2-DQ3 haplotype. Total RNA was extracted from peripheral blood of the propositus was converted to first-strand cDNA using reverse transcriptase. The cDNA was amplified by the polymerase chain reaction (PCR) using HLA-B locus-specific primers. The PCR product showed no change in size upon polyacrylamide gel electrophoresis (PAGE) compared to that of normal controls, suggesting that HLA-B gene mRNA was normally expressed. The nucleotide sequence of the cDNA was the same as that of B*1501 except at nucleotide 369 or codon 123, where C was replaced with A; TAC encodes Tyr whereas TAA is a stop codon. This point mutation may have truncated the HLA-B molecule of the propositus, resulting in the negative results we obtained with anti-HLA-B sera.

Adult↗
PubMed1997

A high-resolution genotyping method for HLA-C alleles and possible shared HLA-C-B haplotypes between Japanese and Caucasians.

A genotyping system for HLA-Cw alleles using methods of PCR-single-strand conformation polymorphism (SSCP) and PCR-sequence-specific primers (SSP) was developed. Genomic DNA from 167 random healthy Japanese individuals were investigated to determine HLA-C allele frequencies and their associations with HLA-A and -B loci. Nine alleles were frequently detected: Cw*0102 (18.3%), Cw*0304 (12.0%), Cw*1202 (11.4%), Cw*0303 (10.5%), Cw*1403 (10.5%), Cw*0801 (10.2%), Cw*0702 (9.0%), Cw*1402 (6.0%) and Cw*0401 (5.1%). Several HLA-C-B haplotypes such as Cw*0303-B62, Cw*0304-B60, Cw*0501-B44, Cw*0602-B13, Cw*0602-B37, Cw*0702-B7, Cw*1202-B52, Cw*1402-B51 and Cw*1502-B51 were found to be shared by Japanese and Caucasians. With the PCR-SSCP method we could detect differences in each exon of HLA-C alleles, at a low cost and simply. This method is suitable for sequence-level matching with a relatively small number of samples.

Alleles↗