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K Tadokoro

Publications and source records attributed to K Tadokoro.

At least 145 records · Page 8Linked to original sources
PubMed1994

Degranulation from human eosinophils stimulated with C3a and C5a.

It is unclear what actually induces eosinophil degranulation in vivo. We examined eosinophil cationic protein (ECP) release from normal human eosinophils (Eos) in response to C3a and C5a. C3a and C5a induced remarkable ECP release when Eos were preincubated with cytochalasin B. ECP release induced by C3a or C5a was greater than that induced by PAF at a concentration of 10(-7) M. The ED50 for ECP release was 3 x 10(-8) M and 3 x 10(-9) M for C3a and C5a, respectively. C3a or C5a elicited a rapid and transient rise in [Ca2+]i. These results suggest that C3a and C5a may contribute to hypersensitivity diseases by inducing eosinophil degranulation.

Blood Proteins↗
PubMed1994

Molecular cloning of cDNA encoding the precursor for hamster hypothalamic growth hormone-releasing factor.

The structure of rat and mouse growth hormone-releasing factor (GRF) peptide and precursor shows considerable divergence from that of the human counterpart and also within rodents themselves. To study such structural divergence in another rodent, we cloned a cDNA encoding the GRF precursor from golden hamster. The hamster GRF (haGRF) cDNA clone had an open-reading frame that predicts a haGRF precursor protein with 107 amino acids. The haGRF precursor bore greater overall homology (82%) to the human than the same rodent homologue (58-64%) and contained two processing sites identical to the human sequence that would generate mature haGRF peptide. Furthermore, the haGRF peptide, like human but unlike rat or mouse GRF, consisted of 44 amino acids and also had greater homology to the human (89%) than the rodent sequence (64-75%), conserving a Tyr residue at the N-terminus and an amidated Leu residue at the C-terminus. Thus, both haGRF precursor and peptide are structurally more related to those of human than of other rodents, suggesting that rodent GRF precursor diverged from the human sequence at differential rates within the species.

Animals↗
PubMed1994

[Allergic characteristics of bronchial asthma in the elderly].

Allergic characteristics were investigated in asthma patients older than 60 years of age. Among these asthmatic patients: 1. About 37% showed negative immediate skin response to all antigen extracts tested. 2. The frequency of positive immediate skin response to house dust, house dust mite, Japanese cedar and Alternaria decreased with aging. 3. There was no difference in the frequency of positive immediate skin response to Candida antigen among patients in different age groups. Candida was the antigen that most frequently produced positive immediate skin response among the patients over 50 years old. 4. There was no difference between skin-positive elderly asthmatics and young asthmatics in the frequency of positive IgE antibody titer, bronchial response, conjunctival response and histamine release from peripheral leukocytes by specific antigens. These findings show that atopic asthmatics are less frequently found in elderly asthmatic patients than in young patients. Nevertheless, there is no difference in the characteristics of atopy, except in the response to Candida antigen.

Adult↗
PubMed1994

Protection against natural killer cells by interferon-gamma treatment of K562 cells cannot be explained by augmented major histocompatibility complex class I expression.

Prior study has revealed that the expression of certain major histocompatibility complex (MHC) class I molecules on the membranes of normal or transformed cells can prevent natural killer (NK)-cell-mediated killing. This has been explained by either (1) the target interference model, or (2) the effector inhibition model. In both cases, MHC class I molecules are concerned but the precise mechanisms are still unclear. The erythroleukaemia K562 cell is known as a NK-sensitive target. This sensitivity has been explained mostly as being due to lack of MHC class I antigens on the K562 membrane. However, several recent studies have indicated that the expression of MHC class I antigens on the cell does not solely explain the protection against NK cells. To elucidate the mechanism of NK-cell-mediated killing, we investigated the killing profiles of the K562 cells by NK cells. Previous studies indicated that the NK-sensitive K562 cells can express some MHC class I antigens on their surface, and become protective against NK-cell killing after treatment with human interferon-gamma (hIFN-gamma). In the present study, we show that this resistance is not rendered by MHC class I expression, because addition of anti-MHC class I monoclonal antibodies (mAb) in the killing assay of hIFN-gamma-treated K562 cells, which express MHC class I antigens as the target, did not restore the sensitivity to NK cells. Moreover, we show that spontaneously occurring K562 clones which could not express MHC class I antigens even after hIFN-gamma treatment, could be protected after treatment with the cytokine. Taken together, these results strongly suggest that the susceptibility of K562 cells to NK cell killing is due to some elements distinct from those related to MHC class I antigens.

Antibodies, Monoclonal↗
PubMed1993

Recognition of human insulin in the context of HLA-DRB1*0406 products by T cells of insulin autoimmune syndrome patients and healthy donors.

Our recent study indicated that all the insulin autoimmune syndrome (IAS) patients had specific HLA class II alleles, the DRB1*0406, DQA1*0301, and DQB1*0302, which allowed T cells to proliferate when autologous APC were exposed to human insulin. The study implied that gene products of DRB1*0406, DQA1*0301, and/or DQB1*0302 may be involved in the presentation of human insulin to T cells. We therefore examined T cell response of healthy donors with different HLA phenotypes to human insulin using an autologous MLR system. The T cells from not only IAS patients but also healthy donors were able to proliferate after exposure of human insulin to autologous APC with DRB1*0406, DQA1*0301, and DQB1*0302 products. The class II molecules are considered to be involved in the recognition of human insulin by T cells. The proliferative response of T cells was completely blocked by anti-HLA-DR mAb and not by anti-HLA-DQ mAb or other mAb. Furthermore, human insulin-specific CD4-positive T cell clones were established from blast cells in autologous MLR of PBMC from two healthy donors with DRB1*0406 in the presence of human insulin. Using DRB1*0406-transfected L cells as APC, we confirmed that these T cells clones recognize human insulin in the context of gene products of DRB1*0406. These results provide the first evidence that HLA-DRB1*0406 products act as the dominant restriction element for the presentation of human insulin to T cells, and suggest that this particular class II gene, HLA-DRB1*0406, contributes to the development of IAS.

Antibodies, Monoclonal↗
PubMed1993

Structural organization of MYCN amplicons of neuroblastoma tumors, xenografts, and cell lines characterized by the sequences encompassing the MYCN amplicons in a human neuroblastoma cell line.

We characterized differences in the structural organization of the MYCN amplicons of a number of neuroblastomas by analyzing 8 contigs spanning 330 kb cloned from the MYCN amplicon of a neuroblastoma cell line. Some regions were amplified in almost all specimens, the conserved regions (CRs), and others were differentially amplified in some subsets, the non-conserved regions (NCRs). CRs constituted only 20% of the 330 kb region, with the remainder being NCRs. The regions that inevitably co-segregate with the MYCN gene make up the core, whereas flanking regions are retained at random. If a histogram of the frequency with which the amplified NCR sequences from one specimen match those of the cell line MC-NB-I shows a random distribution, the NCRs would co-segregate with MYCN as a result of random events. However, both the tumors and cell lines/xenografts showed a distribution with two distinct peaks; one from a group containing a small number of sequences with a fairly high degree of homology to the NCRs of MC-NB-I, and the other from a group containing a large number of sequences with little homology. These results indicate that the flanking segments are preferentially co-segregated with MYCN by a non-random mechanism.

Alleles↗
PubMed1993

Genotyping and association analysis of HLA-B61 in Japanese.

The distribution of HLA-B61-related alleles, B*4002-B*4006, was examined in the Japanese population by using PCR-SSO and PCR-RFLP methods. About half of the B61-positive individuals possessed B*4002 and the remaining half possessed B*4006. In addition, these two major B61 alleles were separately associated with different HLA-C alleles: B*4002 exhibited a strong linkage disequilibrium with Cw10, whereas B*4006 was strongly associated with C blank and DR9. Amino acid residues that contribute to the serologic epitopes of the B61 group and their relationships with other HLA-B locus antigens are discussed.

Alleles↗
PubMed1993

[Clinical usefulness of histamine release test in determining allergens in food hypersensitivity].

We examined the clinical usefulness of three diagnostic tests including the histamine release test, RAST and prick test in determining which of a total of 349 allergens were responsible for individual cases of food hypersensitivity. The subjects were 42 children (mean 3.3 years old). When compared with the results of the offending allergen confirmed by elimination and provocation test, each diagnostic test showed a fairly good correlation in percentage agreement and negative agreement, but there was poor correlation in positive agreement (histamine release test 58.1%, RAST 62.8%, prick test 48.8%). False positive results were more frequently observed in RAST (12.6%) as compared with the histamine release test (4.0%) and prick test (2.3%). McNemar's analysis demonstrated that the histamine release test, but not RAST or the prick test, was matched the diagnosis by elimination and provocation test (alpha = 0.30). These results suggest that the histamine release test is more clinically useful than RAST or the prick test in the diagnosis of food hypersensitivity.

Allergens↗
PubMed1992

[Clinical evaluation of hepatic scintigraphy using 99mTc-GSA].

Functional hepatic imaging was performed using 99mTc-DTPA-galactosyl human serum albumin (99mTc-GSA), a radiolabeled ligand that reacts specifically to the asialoglycoprotein receptor that resides at the plasma membrane of hepatocytes, in 21 patients: five with chronic active hepatitis (CAH), 14 with compensative liver cirrhosis (LC), one with chronic inactive hepatitis and one with acute hepatitis. The former two diseases were mainly investigated. Serial liver images were acquired at the rates of 10 sec/frame for 0-5 min and 2 min/frame for 6-30 min after the injection of 99mTc-GSA, and the images were compared with 99mTc-phytate images in 2 patients with CAH and 11 with LC, and those with portal scintigrams using 123I-iodoamphetamine (IMP) in 3 patients with LC. The images using 99mTc-GSA were in better agreement with hepatic function than those using 99mTc-phytate, and with the findings of portal scintigraphy using 123I-IMP. LHL15 (liver/liver and heart radioactivities at 15 min after the injection of 99mTc-GSA) correlated with the hepaplastin test (r = 0.978 in CAH, and r = 0.544 in LC), indicators of hepatic reserve. These results suggest that liver scintigraphy using 99mTc-GSA might be a useful method for evaluating liver function.

Adult↗
PubMed1992

Genomic organization of the human WT1 gene.

We have analyzed the genomic structure of the human WT1 gene, one of the recessive oncogenes for Wilms' tumor at chromosome 11p13. By analyses of three cosmids covering the WT1 gene as well as products generated by polymerase chain reaction, cleavage sites for 10 restriction enzymes were mapped in a region of about 80 kb, and the positions of 10 exons were defined. We also mapped two polymorphic sites for TaqI. Our genomic map will be useful to analyze DNA abnormalities sometimes found in the tumors, as well as loss of heterozygosity.

Base Sequence↗
PubMed1992

Intragenic homozygous deletion of the WT1 gene in Wilms' tumor.

One example of intragenic homozygous deletion of the WT1 gene on chromosome 11p13 was found after screening 42 samples of Wilms' tumor DNA from Japanese patients. After construction of a restriction map for the genomic sequence covering the 3' half of the gene, the deletion was analysed at the nucleotide sequence level. The deletion occurred in the patient's germline on his paternal chromosome, and most of the short arm of his maternal chromosome 11 was subsequently lost in the tumor. The size of the deletion was about 8 kb, removing exons 6 and 7 and resulting in premature termination. The deletion seemed to be created by recombination between short homologous sequences found in an Alu repeat, with a 16-bp duplication left at the junction. This case conforms to a two-hit model for the genesis of a certain group of tumors, and supports the hypothesis that WT1 is one of the recessive oncogenes responsible for Wilms' tumor.

Base Sequence↗
PubMed1992

[Evaluation of interstitial shadows by thin slice computed tomography].

We developed a method for evaluation of interstitial shadows by thin slice computed tomography (CT). We studied thirty-seven cases with interstitial shadows confirmed by thin slice CT, and 13 normal cases. Thin slice CT was scanned on 3 levels: 1) at the aortic arch, 2) about 2 cm below the carina, and 3) about 1 cm above the right diaphragm. Each level was scanned bilaterally to produce 6 regions of interest (ROI); CT numbers were recorded from each ROI. CT numbers ranging from -1000 to 100 Hounsfield units (H.U.) were classified into 4 different bands, -1000 - (-900) H.U. (low band), -900 - (-750) H.U. (medium low band), -750 - (-500) H.U. (medium high band), and -500 - 100 H.U. (high band), for cases with interstitial shadows and for normal cases. We calculated the prevalence of CT numbers in each band for both normals and subjects with interstitial shadows. Compared to the normals, subjects with interstitial shadows showed fewer pixels in the medium low band and more pixels in the medium high and high bands. Furthermore, the prevalence of CT numbers in each band correlated with %TLC, %VC, and pulmonary diffusing capacity. We conclude that thin slice CT is a useful method for evaluation of the extent and characteristics of interstitial shadows.

Alveolitis, Extrinsic Allergic↗
PubMed1991

Enzymatic dispersion of mast cells from human sinus mucosa: characterization of histamine release and its comparison with chopped fragments of the tissue.

Functional characteristics of mast cells in chopped fragments from sinus mucosa, which was dissected from patients with chronic sinusitis, were compared with those from dispersed cells prepared by enzymatic treatment. The results obtained in this study were the following. (1) Both chopped fragments and dispersed cells released histamine in a dose-dependent manner when incubated with anti-IgE. However, higher histamine release was always observed in dispersed cells. (2) Although no differences in the ability to reduce histamine release with salbutamol or forskolin could be observed between chopped fragments and dispersed cells, staurosporin and p-bromophenacyl bromide were more active on dispersed mast cells than chopped fragments. (3) Passive sensitization of dispersed cells with an allergic serum containing IgE to mite could be achieved only after elution of IgE on the cells with lactic acid.

Acetophenones↗