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Biomedical subjects

Yasuyuki Okamoto

Publications and source records attributed to Yasuyuki Okamoto.

18 recordsLinked to original sources
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↗
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↗
PubMed2002

Enhanced GLUT2 gene expression in an oleic acid-induced in vitro fatty liver model.

Previous reports have shown that the liver-type glucose transporter GLUT2 gene expression is upregulated in the liver of obese and diabetic animals and in human subjects. This phenomenon is correlated with an increased glucose output from the liver; however, the regulatory mechanism is not clear. To investigate the relationship between hepatic steatosis, frequently found in obese and diabetic patients, and GLUT2 gene expression, we developed an oleic acid-induced in vitro fatty liver model. Lipid-accumulated cells morphologically mimicking hepatic steatosis were successfully induced in the human HepG2 cell line by 24-h culture with oleic acid at 1 mM. The cells with steatosis showed increased levels of intracellular triglycerides and apolipoprotein B, which were reduced in the presence of bezafibrate at 100 &mgr;g/ml. GLUT2 mRNA expression estimated by semi-quantitative reverse transcription polymerase chain reaction was increased in the cells with steatosis. Bezafibrate inhibited GLUT2 mRNA expression in the cells with and without steatosis. These results suggest that hepatic steatosis causes the enhancement of hepatic GLUT2 mRNA expression, which may be associated with gluconeogenesis and insulin resistance.

Journal Article↗
PubMed2002

Gamma heavy chain disease screening showing a discrepancy between electrophoretic and nephelometric determinations of serum gamma globulin concentration.

A 75-year-old woman with rheumatoid arthritis showed a discrepancy between the reduced level of serum gamma globulin on cellulose acetate electrophoresis and the normal level of serum IgG determined by laser nephelometry. Although no M-peak was detectable on cellulose acetate electrophoresis, immunoelectrophoresis of the patient's serum revealed a monoclonal protein reacting with anti-IgG antiserum but not with anti-kappa or anti-lambda light chain antiserum. Western blotting of the patient's serum showed abnormal low-molecular-weight gamma chains. Thus, the patient was diagnosed with gamma heavy chain disease. A comparison of gamma globulin levels determined by different methods may be useful when screening for this disease.

Aged↗
PubMed2002

[Determination of fractal dimension using digital nuclear image of lymphocyte].

Microscopic morphological findings in smeared and stained blood cells are difficult to be characterized quantitatively. However, a recent progress in digital image processing has been enabled to express some of these findings quantitatively. In this report, we propose the usefulness to determine "box" fractal dimension of nuclear image of lymphocyte. Fractal dimension was determined in digital 256-grayscale images of normal, atypical and leukemic lymphocytes by a box-counting method after extracting a nuclear image out of a cellular image, binalyzing and thinning it. The results suggest that fractal dimensions of nuclear images are mainly correlated with changes in chromatin appearance. Fractal dimension could be a useful quantitative parameter for cytological differentiation between normal and atypical lymphocytes.

Cell Nucleus↗
PubMed2002

[Elimination of electrocardiogram artifacts from electroencephalogram records by using the simultaneously recorded electrocardiograph data].

We developed a simple method to eliminate electrocardiogram (ECG) artifacts from electroencephalogram (EEG) records by using simultaneously recorded ECG data. The raw EEG data, the real EEG data and the ECG data were regarded as multi-dimensional vectors Ea, Er and C, respectively. Also, the ECG data, with reduced amplitude whose coefficient was denoted as 'k', were assumed to be overlapped on the real EEG. These assumptions introduced the equations [Ea = Er + k.C], [Er.C = 0] and finally [k = Ea. C/C.C]. This calculation method was implemented by a Macintosh computer using data exported from digital EEG recordings (sampled at 200 Hz with 16-bit resolution). In several subjects, sampling intervals of 5 or 10 seconds for calculation succeeded in eliminating ECG artifacts. However, regardless of the sampling interval, this elimination condition was not always efficient in several other subjects, including a brain-dead patient. It was suggested that the ECG data used were insufficient for the calculation, because only one hand-to-hand reference was used for simultaneous recording, as usual. This one ECG reference was able to express only one ECG projection. Then two other hand-to-foot references of ECG were added to the recordings, and the elimination procedure was performed using all of the simultaneously recorded ECG data at the three references. Consequently, elimination was much improved in most subjects, including the brain-dead patient. Our method may be useful for eliminating ECG artifacts without changing reference electrodes.

Artifacts↗