PubMed Health⌕ Search

Biomedical subjects

Yasuyuki Okamoto

Publications and source records attributed to Yasuyuki Okamoto.

At least 19 recordsLinked to original sources
PubMed2006

TSH receptor antibody measurements and prediction of remission in Graves' disease patients treated with minimum maintenance doses of antithyroid drugs.

Prediction of remission is one of the main problems of antithyroid drug (ATD) therapy for Graves' disease especially in patients who are treated with a minimum maintenance dose of ATD. We evaluated the ability of new sensitive TSH receptor antibody (TRAb) assays to predict remission in Graves' patients using two commercially available kits (TRAb-CT from Cosmic Corporation and TRAb-Dyno from Yamasa Corporation), compared to the original PEG assay. When a euthyroid state was achieved for more than 6 months with methimazole 5 mg/day or propylthiouracil 50 mg/day and thereafter for three months with 5 mg every other day or 50 mg every other day, respectively, we discontinued ATD medication. One year of observation after discontinuation of ATD was completed in 71 patients (60 females, median age 43 years, range 18-71), and TRAb values from these patients were analyzed in relation to prognosis. Twenty-six (37%) of the 71 patients had relapse of thyrotoxicosis and 45 remained euthyroid. The median TRAb levels in the relapse group were significantly higher than those in the remission group (P < 0.05). Relapse occurred in 15/51 patients negative by TRAb-CT, in 11/20 patients positive by TRAb-CT (chi2 = 4.1; P < 0.05), in 11/42 patients negative by TRAb-Dyno and in 15/29 patients positive by TRAb-Dyno (chi2 = 4.8; P < 0.05). By contrast, relapse occurred in 23/64 patients with negative TRAb by PEG assay and in 3/7 patients with PEG assay positive values (n.s.). All patients with TRAb-CT values of 30% inhibition or greater, or TRAb-Dyno values of 3.0 U/L or greater relapsed during the observation period. Thus, measurement of TRAb by the new sensitive assays is useful for prediction of remission in our patients.

Adolescent↗
PubMed2006

Unusual gamma heavy chain disease protein in a patient with splenic marginal-zone lymphoma.

We conducted an electrophoretic analysis of monoclonal gamma-globulin found in the serum of a patient with splenic marginal-zone lymphoma. This monoclonal protein showed electrophoretic mobility to the gamma region and reacted with anti-immunoglobulin (IgG) antiserum but not with anti-kappa or anti-lambda light chain antisera. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting of the monoclonal protein-rich gamma-globulin fraction extracted from the sliced gel revealed the presence of two types of abnormal IgG molecule, low- and high-molecular-weight IgG, neither of which reacted with anti-kappa or anti-lambda light chain antisera. Additionally, an abnormal high-molecular-weight gamma heavy chain was identified by reducing SDS-PAGE. These findings suggest that this monoclonal protein is composed only of gamma heavy chains of normal and larger size. The presence of abnormal serum immunoglobulin composed of only gamma heavy chain has been known as a fundamental feature of gamma heavy chain disease (HCD). However, the unique composition of monoclonal gamma-globulin makes our case distinct from typical gammaHCD, which is characterized by an abnormal truncated low-molecular-weight gamma heavy chain. Thus, the unusual monoclonal protein may have been produced by a somatic mutation of IgH gene associated with splenic marginal-zone lymphoma.

Female↗
PubMed2006

[Genetic analysis of idiopathic renal hypouricemia: a case report and estimation of allelic frequency of the mutation].

Idiopathic renal hypouricemia is a hereditary disease characterized by abnormally increased renal excretion of urate. This disorder is primarily caused by a mutation of the SLC22A12 gene encoding human urate transporter 1 (URAT1). We recently encountered a case of severe hypouricemia (urate level: 0.5mg/dl in serum, 1.19g/l in urine), which was discovered when a 24-year-old male medical student was carrying out a practical examination of his own blood sample. The student was clinically healthy and showed no other abnormal laboratory findings, but his elder brother had a history of exercise-induced acute renal failure (ARF). DNA sequencing of the SLC22A12 gene demonstrated one nonsense mutation, W258X in this student. To confirm the genotype and for use in screening for W258X, we developed a polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) assay using a mismatched primer to introduce a new HinfI restriction site into the PCR products of exon 4. The genotype of our case was then confirmed as being heterozygous, with W258X and wild-type genes. We next used this PCR-RFLP assay to examine the frequency of W258X in 64 pairs of anonymous DNA and serum samples from various Japanese patients. Three patients were found to have W258X (all heterozygous). The allelic frequency of W258X was 2.34%. Considering that hypouricemia-related ARF is frequent in children and young adults, it may be worthwhile to screen for renal hypouricemia in these age groups. Our PCR-RFLP assay may be useful for this purpose.

Acute Kidney Injury↗
PubMed2006

Surveyor nuclease-based genotyping of SNPs.

Surveyor nuclease, a single-strand-specific endonuclease that cleaves DNA at the 3' side of a base-mismatch site in both DNA strands, can be used for genotyping of SNPs by preparing two different types of a heteroduplex: one from mutant DNA fragments and the other from a mixture of wild-type and mutant fragments. We show an example of this technique and propose that it can be used with some advantages instead of RFLP analysis.

DNA↗
PubMed2006

[TSH receptor antibody measurements--the progress and the point at issue].

A half century has passed since Adams and Purves discovered the long acting thyroid stimulator which is now known as TSH receptor antibody (TRAb). The progress and the point at issue in measurement of TRAb is reviewed. Second generation TRAb assays based on inhibition of labeled TSH binding to TSH receptors coated on tubes or plate wells are available in clinical use, and show sufficient sensitivity and specificity for the diagnosis of Graves' disease. A highly sensitive thyroid stimulating antibody assay based on stimulation of cAMP release from frozen porcine thyroid cells is also available, and is useful for the evaluation of Graves' ophthalmopathy. Third generation TRAb assays and automated TRAb assays are developing.

Animals↗
PubMed2005

Pancreatic endocrine neoplasm can mimic serous cystadenoma.

A 57-yr-old female patient was referred to our hospital with a cystic lesion of the head of the pancreas that had been noted on abdominal computed tomography (CT). Endoscopic ultrasonography (EUS) showed a 3.0 cm rounded mass in the head of the pancreas. EUS images showed that the tumor had a solid component consisting of multiple microcysts separated by septae and a cystic component consisting of a macrocystic lesion. Thus, the tumor was suspected of being a serous cystadenoma (SCA). However, the histopathological diagnosis based on endoscopic ultrasound- guided fine-needle-aspiration biopsy (EUS-FNAB) was that of a pancreatic endocrine neoplasm (PEN). Surgical resection was performed. Despite having very similar macroscopic findings to SCA, microscopic examination revealed that the patient's tumor was definitely a PEN. This case suggests that it is very difficult to distinguish PENs from SCAs based solely on imaging methods. EUS-FNAB is essential for determining the appropriate therapeutic strategy, as it provides the histopathological diagnosis.

Biopsy, Needle↗
PubMed2005

Molecular typing of methicillin-resistant Staphylococcus aureus by PCR-RFLP and its usefulness in an epidemiological study of an outbreak.

A new convenient molecular typing method, simultaneous polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) analysis, for three different genes of methicillin-resistant Staphylococcus aureus (MRSA) was evaluated using 35 isolates of MRSA and comparing results with those previously reported for sequencing-based spa typing. Twenty-nine isolates of the most frequent protein A (spa) type were discriminated into 6 different types by PCR-RFLP. In contrast, spa typing could discriminate only 1 of the 19 most frequent PCR-RFLP-type isolates. The discriminatory powers of the two methods were equal for the other isolates. These results suggest that PCR-RFLP has the advantages of both relative easiness and greater discriminatory power than spa typing. We also report the case of a suspected outbreak in which PCR-RFLP was sufficient for ruling out the possibility of an outbreak. Thus, PCR-RFLP is preferable as a preliminary screening method for epidemiological studies of nosocomial infection caused by MRSA.

Anti-Bacterial Agents↗
PubMed2004

Differential effects of interferon-gamma on production of trypanosome-derived lymphocyte-triggering factor by Trypanosoma brucei gambiense and Trypanosoma brucei brucei.

Trypanosome-derived lymphocyte-triggering factor (TLTF) produced by Trypanosoma brucei brucei stimulates production of interferon-gamma (IFN-gamma) by CD8+ T cells, and it is reported that, in turn, IFN-gamma stimulates proliferation of T. b. brucei. We studied the role of TLTF in trypanosome proliferation using the Wellcome strain (WS) of Trypanosoma brucei gambiense and the ILtat 1.4 strain (IL) of T. b. brucei. Increase in the number of WS in infected rats is more rapid than IL and corresponds with comparatively higher levels of IFN-gamma. Production of IFN-gamma, as measured by protein and messenger RNA (mRNA) levels, was maintained by splenocytes from WS-infected rats, whereas levels decreased in IL-infected rats, accompanied by prolongation of infection. Expression of TLTF mRNA by in vitro-cultured WS was promoted in a dose-dependent fashion by addition of recombinant rat IFN-gamma at all concentrations tested. The addition of lower concentrations of IFN-gamma to cultured IL increased expression of TLTF mRNA, whereas, in contrast to WS, addition of 100 and 1,000 U/ml IFN-gamma decreased expression of TLTF by IL. These results show that unlike WS, elevated IFN-gamma concentrations lead to decreased TLTF production by IL. It is believed that decreased TLTF production in IL-infected rats leads to lowered IFN-gamma production, thereby slowing IL proliferation.

Animals↗
PubMed2004

The discrepancy between electrophoretic and nephelometric determinations of serum gamma-globulin level.

We studied the significance of discrepancies in correlation between serum gamma-globulin levels electrophoretically estimated and immunoglobulin levels nephelometrically determined. Discrepancies appeared in cases with IgA myeloma, macroglobulinemia, and rare types of dysgammaglobulinemia frequently overlooked in serum electrophoresis, IgD myeloma and gamma-heavy chain disease. It is suggested that comparison of the gamma-globulin levels by the different methods is a simple and useful method of detecting these dysgammaglobulinemias.

Dysgammaglobulinemia↗
PubMed2003

[Laboratory medicine in the obligatory postgraduate clinical training system--common clinical training program in the department of laboratory medicine in our prefectural medical university hospital].

I propose a postgraduate common clinical training program to be provided by the department of laboratory medicine in our prefectural medical university hospital. The program has three purposes: first, mastering basic laboratory tests; second, developing the skills necessary to accurately interpret laboratory data; third, learning specific techniques in the field of laboratory medicine. For the first purpose, it is important that medical trainees perform testing of their own patients at bedside or in the central clinical laboratory. When testing at the central clinical laboratory, instruction by expert laboratory technicians is helpful. The teaching doctors in the department of laboratory medicine are asked to advise the trainees on the interpretation of data. Consultation will be received via interview or e-mail. In addition, the trainees can participate in various conferences, seminars, and meetings held at the central clinical laboratory. Finally, in order to learn specific techniques in the field of laboratory medicine, several special courses lasting a few months will be prepared. I think this program should be closely linked to the training program in internal medicine.

Education, Medical, Graduate↗
PubMed2003

Determination of the components in erythrocytes using an automated analyzer.

Determination of the biochemical components in erythrocytes should provide unique pathophysiological information. We optimized a simple alcohol binding method for the selective removal of hemoglobins from hemolysates, and enabled simultaneous determination of several components in erythrocytes using commercially available assay kits in an automated analyzer. Venous blood was collected in a vacutainer containing lithium heparin. The washed cells were hemolyzed with distilled water, frozen, and then thawed. Nine volumes of the hemolysates were mixed with one volume of Tris-HCl buffer. One volume of n-butanol was then added to nine volumes of the buffered hemolysates. After vigorous mixing, the mixture of n-butanol and hemolysates was left to stand. The butanol-bound hemoglobins were precipitated by centrifugation, and the clear supernatant below the butanol layer was applied directly to an automated analyzer. Using sera, we determined the effects of the hemoglobin removal procedures on the chemical analytes. Sufficient recovery was noted in most analytes, except for several enzyme activities and lipids. Accordingly, we determined five components present in erythrocytes: creatine, potassium, magnesium, and aspartate aminotransferase as well as superoxide dismutase activities in healthy subjects. We suggest that our simple method is applicable to the simultaneous determination of erythrocyte components in routine laboratory tests.

Adult↗