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Biomedical subjects

M Hakoda

Publications and source records attributed to M Hakoda.

At least 19 recordsLinked to original sources
PubMed2001

Activated human T cells directly induce osteoclastogenesis from human monocytes: possible role of T cells in bone destruction in rheumatoid arthritis patients.

OBJECTIVE: To elucidate the direct role of human T cells in the induction of osteoclastogenesis in rheumatoid arthritis (RA), by studying human monocytes and the pathogenetic roles of receptor activator of nuclear factor kappaB ligand (RANKL), RANK, and osteoprotegerin (OPG). METHODS: Synovial tissue obtained at total knee replacement was stained immunohistologically using anti-RANKL, CD3, and CD4 antibodies. Synovial fluid was obtained from patients with RA, osteoarthritis (OA), gout, or trauma. Concentrations of the soluble form of RANKL (sRANKL) and OPG in the synovial fluid were measured by enzyme-linked immunosorbent assay. Activated T cells from peripheral blood mononuclear cells (PBMC) of healthy volunteers were cultured with human monocytes from PBMC. RESULTS: Immunostaining of the synovial tissue of RA patients demonstrated that RANKL-positive cells were detected in a subset of fibroblast-like synoviocytes and infiltrating mononuclear cells. Double immunostaining revealed that RANKL-positive cells were detected in a subset of CD3+ cells and CD4+ cells. An increased concentration of sRANKL and a decreased concentration of OPG were detected in synovial fluid from RA patients. The ratio of the concentration of sRANKL to that of OPG was significantly higher in synovial fluid of RA patients than in synovial fluid of patients with OA or gout. The activated T cells expressing RANKL induced osteoclastogenesis from autologous peripheral monocytes. The role of RANKL in this osteoclastogenetic process was confirmed by dose-dependent inhibition by OPG. CONCLUSION: The present study is the first to demonstrate osteoclastogenesis using human-derived T cells and monocytes. In addition, the present findings suggest that excess production of RANKL by activated T cells increases the level of sRANKL in synovial fluid and may contribute to osteoclastic bone resorption in RA patients.

Antibodies↗
PubMed2001

T-cell responses to mitogens in atomic bomb survivors: a decreased capacity to produce interleukin 2 characterizes the T cells of heavily irradiated individuals.

Significant decreases in the fraction of lymphocytes that are CD4(+) and increases in serum levels of some classes of immunoglobulin have been reported to occur in atomic bomb (A-bomb) survivors and in victims of the Chernobyl nuclear plant accident. To investigate the long-term effects of nuclear radiation on cellular immunity in more detail, we used limiting dilution assays with peripheral blood mononuclear cell preparations to analyze the T-cell responses of 251 A-bomb survivors exposed to less than 0.005 Gy and 159 survivors exposed to more than 1.5 Gy. The percentages of CD2-positive cells that were capable of proliferating in response to phytohemagglutinin (PHA) in the presence of exogenous interleukin 2 (IL2) did not differ substantially between distally exposed and more heavily exposed survivors. The heavily exposed survivors appeared to possess fewer T cells that were capable of proliferating in response to concanavalin A (Con A) or of producing interleukin 2. Assuming that CD4 T cells were the ones primarily responsible for producing IL2 in response to Con A, we were able to estimate how many cells in any given CD4 T-cell population were actually producing IL2. The results indicated that peripheral blood samples from heavily exposed survivors contained significantly fewer IL2-producing CD4 T cells than did similar samples from distally exposed survivors, indicating that significant exposure to A-bomb radiation may have a long-lasting negative effect on the capacity of CD4 T-cell populations to produce IL2.

Adult↗
PubMed2000

KL-6 as a novel serum marker for interstitial pneumonia associated with collagen diseases.

OBJECTIVE: To investigate the diagnostic value of the serum concentrations of KL-6, a mucinous glycoprotein expressed on type II pneumocytes, for interstitial pneumonia (IP) in various collagen diseases. METHODS: Serum KL-6 levels were measured by ELISA. RESULTS: The mean values and the positive rates of serum KL-6 levels for patients with rheumatoid arthritis, systemic sclerosis, or polymyositis/dermatomyositis with IP were significantly higher than those without IP. Sensitivity, specificity, positive and negative predictive values of serum KL-6 level for IP associated with collagen diseases were 60.7, 98.9, 97.4, and 77.1%, respectively. The mean serum KL-6 level of patients with active IP was significantly (p = 0.0001) higher than that of patients with inactive IP. Serum KL-6 levels increased with the deterioration of IP, while the successful treatment of IP resulted in a significant decrease of these levels. CONCLUSION: Serum KL-6 concentration levels are a useful marker for diagnosis and evaluation of the disease activity of IP associated with collagen diseases.

Adult↗
PubMed1998

Optimal range of serum urate concentrations to minimize risk of gouty attacks during anti-hyperuricemic treatment.

To find an optimal range of urate concentrations wherein the risk of attacks during the initial 6 months of treatment is minimized, data from 350 gouty patients treated with anti-hyperuricemic drugs were retrospectively analyzed. We determined the optimal range of urate concentrations to be 4.6-6.6 mg/dl. If urate concentrations were within this range, the risk ratio of an attack as opposed to outside of the range was 0.705 (95% confidence interval, 0.629-0.791). The increase (or decrease) in urate concentration in one month associated with minimal risk of gouty attacks was also determined. The lowest risk ratio of attack (0.451) occurred at a range of -0.1 to 0.6 mg/dl/month increase in urate concentrations (95% confidence interval, 0.310-0.655). In conclusion, we propose that urate concentrations during the initial 6 months of anti-hyperuricemic therapy should be maintained within a range of 4.6-6.6 mg/dl, and reduction in the urate concentrations during treatment should be as slow as possible.

Biomarkers↗
PubMed1998

A germline mutation abolishing the original stop codon of the human adenine phosphoribosyltransferase (APRT) gene leads to complete loss of the enzyme protein.

Adenine phosphoribosyltransferase (APRT) is a purine metabolic enzyme and a homozygous deficiency in this enzyme causes 2,8-dihydroxyadenine urolithiasis. Various germline abnormalities have been described, but we report here a unique type of germline mutation in a homozygous individual (SY) who had excreted 2,8-dihydroxyadenine crystals. In SY, TCA was substituted for the physiological stop codon TGA. This base substitution generates a new HinfI restriction site, and, using the polymerase chain reaction and subsequent digestion by this enzyme, it was confirmed that SY is homozygous for the base substitution. This base change is unique in that it generates an open reading frame that extends to the poly(A) addition site. The amount of mRNA in transformed B cells from SY was approximately a quarter of that in control subjects and no APRT proteins were detected. In eukaryotes, unlike in prokaryotes, no rescue systems for defective polypeptide termination caused by a missing stop codon have been found. Therefore, the outcome of the defect of SY is unclear from present knowledge about termination of polypeptide synthesis. Investigations into the mechanisms of the absence of protein in the cells of SY may lead to a better understanding of the physiological and nonphysiological termination of polypeptide synthesis in eukaryotic cells.

Adenine Phosphoribosyltransferase↗
PubMed1998

Association of HLA class I and class II alleles with myositis in Japanese patients.

OBJECTIVE: To investigate the correlation of HLA class I and class II antigens and alleles with various forms of myositis in Japanese patients. METHODS: Eighty-four Japanese patients with myositis [22 with polymyositis (PM), 46 with dermatomyositis (DM), 16 with myositis overlapping with other collagen vascular diseases] were typed serologically for HLA-A, B, C antigens. HLA-DRB1, DQA1, and DQB1 alleles were determined by polymerase chain reaction dependent DNA typing methods. Fifty-eight Japanese controls were typed serologically while HLA-DRB1, DQA1, and DQB1 allele typing was carried out in 175, 95, and 104 controls, respectively. RESULTS: HLA-B7 was higher in patients than controls [20.2 vs 6.9% in controls: p=0.02, odds ratio (OR)=3.4]. The increase of HLA-B7 was largely dependent on the increase in overlap patients (37.5%; p=0.005, OR=8.1). HLA-A24 and B52 were significantly decreased in PM as compared to DM, while CW3 was significantly increased in PM versus DM. DRB1*08 alleles were significantly increased in patients (36.9 vs 20.5% in controls; p=0.004, OR=2.3), especially in PM and DM. DQA1*0501 and DQB1*0301 were significantly decreased in patients [4.8 vs 13.7% in controls; p=0.04, OR=0.32, and 8.3 vs 20.2% in controls; p=0.02, OR=0.36, respectively]. CONCLUSION: HLA-class I and class II alleles associated with Japanese patients with myositis may be different from those associated with Caucasian patients.

Alleles↗
PubMed1997

Lack of association of HLA-DRB1 genotype with radiologic progression in Japanese patients with early rheumatoid arthritis.

OBJECTIVE: To evaluate the role of HLA-DRB1 genotypes in the development and progression of the rheumatoid arthritis (RA) disease process. METHODS: Patients with polyarthritis of < 1 year in duration were consecutively enrolled in the study. Other inclusion criteria were no diagnosis of inflammatory diseases other than RA, and no history of taking disease-modifying antirheumatic drugs or steroids. Patients were evaluated every 4 weeks, and radiographs of the hands/wrists and feet were taken at presentation and 1 year later. HLA-DRB1 genotypes were determined by polymerase chain reaction and restriction fragment length polymorphism methods. RESULTS: We enrolled 198 patients (median disease duration 5.0 months) and 150 controls. The frequency of individuals with DRB1*0405 and *0410 was significantly higher in the patients than in the controls. Homozygous states for DRB1 alleles with the RA-related shared epitope (SE) were associated with increased susceptibility for the development of polyarthritis (odds ratio 3.4, 95% confidence interval 1.5-7.7). None of the DRB1 alleles or SE genotypes correlated with the presence of bone erosion at presentation or 1 year later. CONCLUSION: DRB1 alleles with SEs were associated with the development of polyarthritis but not with early radiographic progression of the disease process.

Adolescent↗
PubMed1997

An asymptomatic germline missense base substitution in the hypoxanthine phosphoribosyltransferase (HPRT) gene that reduces the amount of enzyme in humans.

A 40-year-old normouricemic (5.5 mg/dl) male showed 46% hemolysate and 37% lymphoblast hypoxanthine phosphoribosyltransferase (HPRT) activities but was otherwise completely free of symptoms. His genomic DNA and cDNA had a missense base substitution (CAT-to-CGT in codon 60) leading to the amino-acid substitution His-to-Arg. Western blot analysis revealed that the amount of HPRT protein in lymphoblasts from this individual was 25%-50% of normal cells, suggesting that the decrease in the amount of enzyme protein was responsible for the partial deficiency. This provides the first clear evidence that a genomic missense mutation at the HPRT locus leads to a decrease in the amount of the enzyme protein but that otherwise it has no evident adverse effects in the hemizygote (asymptomatic mutation).

Adult↗
PubMed1997

Intervention of somatic mutational events in vivo by a germline defect at the adenine phosphoribosyltransferase locus.

Both germline and somatic mutations are known to affect phenotypes of human cells in vivo. In previous studies, we cloned mutant peripheral blood T cells from germline heterozygous humans for adenine phosphoribosyltransferase (APRT) (EC 2.4.2.7) deficiency and found that approximately 1.3 x 10-4 peripheral T cells had undergone in vivo somatic mutations. Loss of heterozygosity (LOH) was the major cause of the mutations at the APRT locus since approximately 80% of the mutant T cell clones exhibited loss of normal alleles. In the present study, we identified three heterozygous individuals for APRT deficiency (representing two separate families), in whom none of the somatic mutant cells exhibited LOH at the APRT locus. The germline mutant APRT alleles of these heterozygotes from two unrelated families had the same gross DNA abnormalities detectable by Southern blotting. None of the germline mutant APRT alleles so far reported had such gross DNA abnormalities. The data suggest that the germline mutation unique to these heterozygous individuals is associated with the abrogation of LOH in somatic cells. The absence of LOH at a different locus has already been reported in vitro in an established cell line but the present study describes the first such event in vivo in human individuals.

Adenine Phosphoribosyltransferase↗
PubMed1997

Generation and molecular characterisation of monoclonal IgG4 rheumatoid factor from a patient with rheumatoid arthritis.

OBJECTIVE: To characterise IgG4 rheumatoid factor (RF) at the molecular level from a patient with rheumatoid arthritis. METHODS: B cells were cloned from the peripheral blood of a patient with rheumatoid arthritis, using EB virus transformation. The supernatants of the clones were screened for IgG RF activity by ELISA. Nucleotide sequences of the expressed immunoglobulin heavy and light chain genes of one IgG RF producing clone were determined by direct sequencing of the products of a polymerase chain reaction. RESULTS: One clone producing monospecific IgG4 RF was obtained. Sequence analysis of the heavy and light chain genes suggested the accumulation of somatic mutations resulting in amino acid replacement in complementarity determining regions. CONCLUSIONS: The results may suggest an antigen driven response in the generation of IgG4 RF in rheumatoid arthritis disease processes.

Amino Acid Sequence↗
PubMed1997

Inactivation of food microorganisms by high-pressure carbon dioxide treatment with or without explosive decompression.

In order to elucidate the sterilization mechanism underlying the explosive decompression system, baker's yeast was pressurized with CO2, N2O, N2, or Ar gas at 40 atm and 40 degrees C for 4h, and then explosively discharged. The survival ratio was markedly decreased only by the treatments with CO2 and N2O, which are relatively soluble gases in water, suggesting that the microorganisms' death may be highly correlated with gas absorption by the cells. Lower decompression rates to atmospheric pressure, however, led to neither any lower reduction of remaining cells nor any smaller release of total cellular proteins. Furthermore, operating with a longer treatment time and smaller number of repetitions was usually more lethal than with a shorter time and more frequent repetition. From these results, most of the yeast cells appear to have been sterilized during the pressurization process. The spore cells of B. megaterium are considered to have been killed in a somewhat different manner, because of their distinct sensitivity to the applied gases.

Argon↗
PubMed1997

[APRT deficiency].

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Adenine Phosphoribosyltransferase↗
PubMed1996

Similarity of in vivo somatic mutations at an autosomal adenine phosphoribosyltransferase locus between T- and B-cells in human peripheral blood.

In vivo somatic mutations have been detected at several human loci by using clonal cultures of peripheral blood T-cells. It has not been fully understood whether or not the somatic mutations in T-cells are similar to those of other cell types. To address this issue, we cloned, from human peripheral blood, T- and B-cells with mutations at an autosomal adenine phosphoribosyltransferase (APRT) locus. For the efficient detection of somatic mutations at the APRT locus, a blood sample from a human individual heterozygous for germline APRT deficiency was used. T- and B-cells deficient in APRT enzyme activity were cloned from peripheral blood mononuclear cells using a selecting agent, 2,6-diaminopurine. The APRT-deficient mutant frequencies were on the order of 10(-4) in both T- and B-cells. The single-strand conformation polymorphism analysis of the APRT DNA of mutant B-cell clones suggested that the molecular mechanisms leading to the APRT deficiency in B-cells were similar to those in T-cells. Our observations suggest that both the frequency and the mode of in vivo somatic mutations occurring spontaneously at general autosomal loci in B-cells are similar to those in T-cells.

Adenine Phosphoribosyltransferase↗