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Biomedical subjects

J Okada

Publications and source records attributed to J Okada.

At least 91 records · Page 5Linked to original sources
PubMed1994

Neuronal expression of Fos protein in the rat brain after baroreceptor stimulation.

The purpose of this study was to identify the CNS neurons that express Fos protein after repeated activation of the baroreceptor reflex. This was done in Wistar rats anesthetized with urethane and alpha-chloralose with careful physiological controls. The intact control rat showed few Fos-immunoreactive (ir) neurons, whereas the anesthetized control rat showed many Fos-ir neurons in the CNS from the medulla oblongata to the forebrain. After repeated stimulation of baroreceptors by pressor responses to phenylephrine (dose), we counted the amounts of Fos-ir neurons (response). The correlation coefficient of the dose-response relationship was high, and significant only in the medial part of the nucleus tractus solitarii (NTS) in the medulla and periaqueductal gray (PAG) in the midbrain, whereas it was comparatively high but insignificant in the commissure and lateral parts of the NTS, caudal and rostral ventrolateral medulla, periambiguus nucleus, dorsal and ventral medullary reticular nuclei, lateral parabrachial nucleus, paraventricular nucleus thalamus, and dorsomedial nucleus hypothalamus. No significant correlation was found in the humoral control nuclei in the preoptico-hypothalamic structure. Fos expression was never detected in the sensory neurons in the ganglia petrosum and nodosum, and in the sympathetic preganglionic neurons in the intermediolateral nucleus of the thoracic spinal cord. This study shows that Fos expression in the CNS neurons is induced not only by baroreceptor stimulation but also by anesthesia and/or sham-operation, and that Fos expression in the NTSm and PAG neurons faithfully responds to baroreceptor stimulation.

Animals↗
PubMed1994

Neuronal expression of Fos and Jun protein in the rat medulla and spinal cord after anoxic and hypercapnic stimulations.

After inhalation of 100% N2 (anoxia) or 8% CO2 (hypercapnia), neurons that express Fos protein (FOS) and/or Jun protein (JUN) were immunohistochemically identified in the CNS of rats anesthetized with urethane and alpha-chloralose. JUN-labeled cells were characteristically found in the respiration-related motor nuclei of the medulla and spinal cord, and in the central chemoreceptive area of the ventral medullary surface on which hypercapnia was more effective than anoxia, whereas FOS-labeled cells were dominant in the respiration-related sensory nuclei of the medulla on which anoxia was more effective than hypercapnia. The results suggest that the peripheral chemoreceptor and the central chemoreceptive pathways in the medulla and spinal cord may be traced by a combination of FOS and JUN expression methods.

Animals↗
PubMed1994

[Tumor blood flow measured by dynamic CT].

A method of measuring tumor blood flow by dynamic CT (DCT) was devised, and the reliability of data obtained by the new method was investigated. The subjects were 16 patients with superficial tumors who underwent measurement of tumor blood flow by both the new DCT-based method and 15O gas positron emission tomography (PET). The results showed that tumor blood flow as measured by the new DCT-based method was about 1.2 times greater than that measured by PET, and both data yielded a straight line passing almost through the origin (proportional relationships); the correlation coefficient was 0.836. On the basis of these studies, it was concluded that the newly devised DCT-based method yields reliable data in the measurement of tumor blood flow.

Adult↗
PubMed1994

Distribution of glutamate- and GABA-immunoreactive neurons projecting to the cardioacceleratory center of the intermediolateral nucleus of the thoracic cord of SHR and WKY rats: a double-labeling study.

We aimed at (1) determining the distribution of glutamate (Glu)- and gamma-aminobutyric acid (GABA)-containing neurons in the brainstem with projections to the cardioacceleratory sympathetic preganglionic neurons in the intermediolateral nucleus (IML) of the upper thoracic cord and (2) determining whether such afferent projections in spontaneously hypertensive rats (SHR) differ from those of control Wistar-Kyoto (WKY) rats. We used a combination of electrophysiological methods to determine the site of HRP injection in the spinal cord and double-labeling methods for plotting the distribution of Glu- and GABA-immunoreactive neurons with projections to this site. HRP/Glu-labeled neurons (possibly glutamatergic) and HRP/GABA-labeled neurons (possibly GABAergic) were detected in 27% and 7% of the total HRP-labeled neurons of the central autonomic nuclei of 3 SHR rats and 3 WKY rats. HRP/Glu-labeled neurons were distributed predominantly ipsilaterally in 20 nuclei of the medulla oblongata, pons and hypothalamus, while HRP/GABA-labeled neurons were distributed in 7 nuclei of the medulla oblongata. No significant differences were found between the average percentages of HRP/Glu-labeled and HRP/GABA-labeled neurons in SHR and WKY rats. These findings indicate that: (1) the Glu-containing neurons represent a greater proportion than the GABA-containing neurons, (2) the proportions of these neurons appear to be similar in WKY and SHR rats and (3) generation of inbred tachycardia and hypertension in SHR rats can not be attributed to the topological and quantitative differences in the distribution of the glutamatergic and GABAergic neurons in the central autonomic nuclei.

Afferent Pathways↗
PubMed1994

FDG-PET for predicting the prognosis of malignant lymphoma.

To evaluate the usefulness of FDG-PET as a predictor of prognosis, 34 patients with untreated malignant lymphoma in the head and neck region were studied. After FDG-PET and treatment, they were observed from 15 to 50 months. Tumors which were aggressive and resistant to treatment tended to show high uptake of FDG. The survival rate of patients with high uptake of FDG, DAR > or = 8, was lower than the rate of the other patients. It is considered to be useful to add FDG uptake of the tumor to other prognostic factors for predicting the prognosis.

Adolescent↗
PubMed1994

FDG-PET for the evaluation of tumor viability after anticancer therapy.

To evaluate positron emission tomography with 18F-fluorodeoxyglucose (FDG-PET) as an diagnostic tool to determine tumor viability after anticancer therapy, fourteen patients were examined by FDG-PET after the end of the treatment. The lesions with residual viable tumor cells showed higher uptake of FDG than surrounding normal soft tissue. The lesions, in which tumor viability was lost or very low, showed higher uptake of FDG in four cases and similar uptake to normal soft tissue in three cases. The residual increased uptake of FDG was considered to be caused by remaining tumor cells and/or inflammatory reaction to anticancer treatment. FDG-PET after anticancer treatment should be interpreted by considering the reaction due to the treatment and the partial volume artifact of PET caused by the limited spatial resolution.

Adolescent↗
PubMed1994

Influence of humoral control peptides on medullary vasomotor control neurons: microstimulation and double-labeling studies using SHR and WKY rats.

To study the influence of humoral control peptides on medullary vasomotor control neurons, angiotensin II (AII), arginine vasopressin (AVP) and atrial natriuretic peptide (ANP) were microinjected into three vasomotor control areas, i.e., the area postrema (AP), the nucleus tractus solitarii (NTS) and the rostral ventrolateral medulla (RVLM), of spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto rats (WKY), and the evoked cardiovascular response was observed. Unlike the injection areas, the threshold dose of one peptide for the cardiovascular response was similar, but the threshold dose differed from peptide to peptide. The threshold dose was lower for AII (0.15-0.29 pmol), in-between for ANP (0.9-1.5 pmol) and higher for AVP (14-30 pmol). No significant difference in the threshold dose was observed between SHR and WKY, suggesting that hypertension in SHR may not be due to the abnormal sensitivity to the three peptides of the vasomotor control neurons in the AP, NTS, and RVLM. The structural basis of the results of the microstimulation experiment was supported by the double-labeling study. The NTS neurons were innervated by (1) the AII-immunoreactive (ir) neurons in both sides of the lateral hypothalamic area (LH), the RVLM and the caudal ventrolateral medulla, and (2) the ANP-ir neurons in both sides of the paraventricular nucleus (Pa) and the LH. The RVLM neurons were innervated by (1) the AII-ir neurons in both sides of the LH and ipsilateral side of the lateral parabrachial nucleus (Pbl) and (2) the ANP-ir neurons in the ipsilateral Pbl. There was no evidence that the AVP-ir neurons in the Pa and the supraoptic nucleus innervate the NTS and the RVLM neurons, or that the AII, ANP or AVP-ir neurons innervate the AP neurons. This study suggests that in common with SHR and WKY rats AII and ANP may influence both the NTS and RVLM not by the humoral pathway but by the neural pathway, and AVP may not influence the three vasomotor control areas by the neural pathway.

Angiotensin II↗
PubMed1994

Lymph node cell proliferation assay in guinea pigs for the assessment of sensitizing potentials of chemical compounds.

The efficacy of a lymph node cell proliferation assay in the guinea pig as a first stage screening method of predicting sensitizing potentials of chemicals was studied by using several haptens. Animals were sensitized by a single 24-hr occlusive patch (24 cp), intradermal injection (id) and a combination of id and 24 cp, at a concentration used for guinea pig conventional contact hypersensitivity assay methods. Control animals were treated with vehicle(s) only. Suspensions of the lymph node cells (LNC) were individually prepared and cultured with [3H]methyl thymidine ([3H]TdR). [3H]TdR incorporation was measured and a stimulation index (SI) was calculated as a ratio of the mean [3H]TdR incorporation in sensitized animals and the mean [3H]TdR incorporation in control animals. LNC sensitized by 24 cp with 2,4-dinitrochlorobenzene proliferated maximally and significantly at day 5, whereas this occurred at day 7 after id sensitization. Significant LNC proliferation and high SI values were obtained successively by a combination of 24 cp and id. Moreover, strongly sensitizing chemicals increased significant LNC proliferation (SI > 2.0); weakly to moderately sensitizing chemicals also induced significant LNC proliferation (SI = 1.3-1.7). On the other hand, a primary irritant, sodium dodecyl sulfate, failed to encourage LNC proliferation (SI approximately 1.0).

Acrolein↗
PubMed1994

Tumor blood flow measured using dynamic computed tomography.

RATIONALE AND OBJECTIVES: A method for measuring the tumor blood flow (TBF) by means of dynamic computed tomography (DCT) was devised and investigated. METHODS: Twenty-seven patients with superficial tumors underwent measurement of TBF by the new DCT method. For all of the 27 patients, the thermal clearance method was employed to measure the relative tumor blood flow (RTBF). For 16 patients, TBF was measured by oxygen-15-gas positron-emission tomography (PET). The TBF values measured by DCT were compared with the RTBF by the thermal clearance method and the TBF by PET. RESULTS: The results demonstrated a linear relationship. CONCLUSIONS: The newly devised DCT method yields reliable data in measuring TBF.

Blood Volume↗
PubMed1994

Renal thrombotic microangiopathy in a patient with rheumatoid arthritis and antiphospholipid syndrome: successful treatment with cyclophosphamide pulse therapy and anticoagulant.

A female patient with a history of migraines and chorea developed polyarthralgia at age 24 and was diagnosed with rheumatoid arthritis. In 1991 she was hospitalized because of impaired renal function and hypertension. Examination revealed thrombocytopenia and the presence of lupus anticoagulant. Antinuclear antibody was weakly positive, but anti-DNA antibody was negative, and no decrease in leukocyte count or complement level was observed. Rheumatoid arthritis with antiphospholipid syndrome was diagnosed. Renal biopsy showed renal thrombotic microangiopathy. This renal lesion was considered to be associated with antiphospholipid syndrome. Cyclophosphamide pulse therapy and anticoagulation therapy decreased proteinuria and improved renal function.

Adult↗
PubMed1994

Current fever of unknown origin 1982-1992.

Since its first rigid definition in 1961 by Petersdorf and Beeson, fever of unknown origin (FUO) has been a major clinical challenge. In this clinical investigation, a retrospective study was conducted on 153 patients meeting the classic criteria of FUO. Collagen-vascular disease was found to be the most common cause of FUO, a change since our last study conducted from 1971 to 1982, replacing infection as the most common disease category of FUO. FUO in elderly patients was also analyzed. By comparing previously documented studies, we observed a new variation in the diseases that are possible causes of FUO. This report will define the present status of FUO in Japan, as well as a comparison with our previous study and other documented studies to determine the shift in the spectrum of diseases causing FUO.

Adolescent↗
PubMed1994

[Clinical microbiology].

The basic purpose of postgraduate education programs in clinical microbiology for the Board of Clinical Laboratory Physicians are mainly to bring up a specialist who can give microbiological laboratory diagnosis. The most important duties of clinical laboratory physicians are to determine causative agents and to select appropriate therapeutic drugs. The guideline for educational curriculum (tentative GIOs) was demonstrated, and the evaluation of education program was discussed.

Clinical Laboratory Techniques↗
PubMed1994

[Association of antiphospholipid antibodies with valvular heart disease in patients with systemic lupus erythematosus].

The purpose of this study was to evaluate the association of antiphospholipid antibodies with the valvular lesions in patients with systemic lupus erythematosus (SLE). Two-dimensional and color Doppler echocardiographic studies were performed in 65 patients with SLE. Antiphospholipid antibodies were assayed in each patient using two methods: anticardiolipin antibody and lupus anticoagulant. Valvular lesions were observed in 43 patients (66.2%). Mitral or aortic regurgitation (MR or AR) were recognized in 37 patients (56.9%). Moderate or severe MR were significantly associated with antiphospholipid antibodies (20.0%, p < 0.01) compared with patients without antiphospholipid antibodies (2%). Four of nine patients with moderate to severe AR or MR developed cerebral infarctions or digital infarctions. It is suggested that there may be a causal link between antiphospholipid antibodies and moderate to severe valvular lesions in SLE.

Adolescent↗
PubMed1994

[123I-OIH renoscintigraphy in children with chronic disorder of glomerulus].

To evaluate the usefulness of 123I-orthoiodohippurate (OIH) renography, 31 patients with chronic disorder of glomerulus, from 5 years to 15 years old, were studied. In chronic glomerulonephritis and nephrotic syndrome with resistance to steroid therapy, Tmax and T 1/2 of the time-activity curve were statistically prolonged. Most of the renograms (time-activity curves) of the patients showed the hypofunction pattern. In most of the patients, other laboratory data, including BUN, PSP test and creatine clearance, didn't show abnormal values. 123I-OIH scan was considered to be a sensitive and useful method to evaluate the renal function in pediatric patients with chronic glomerulonephritis.

Adolescent↗
PubMed1993

Endoscopic incision of persistent ureteral infoldings.

We report 2 cases of persistent ureteral infolding in a four-month-old infant and an eight-year-old boy, both presenting with hydronephrosis. Initial diagnostic evaluation showed multiple pleats in the upper ureter. Endoscopic incision of the pleats relieved hydronephrosis. The concept of persistent ureteral infolding seems to apply to these cases.

Child↗
PubMed1993

Challenge assay in vitro using lymphocyte blastogenesis for the contact hypersensitivity assay.

To confirm positivity in routine guinea pig studies, contact allergenicity was investigated by a challenge assay in vitro using a co-culture of autologous lymphocytes passed through a nylon-wool column and antigen-presenting cells (APCs) modified with or without antigen. Proliferation of the lymphocytes primed with ovalbumin and/or 2,4-dinitrochlorobenzene was antigen specific and dependent on the presence of APCs (peripheral blood monocytes, splenic macrophages and macrophages induced by liquid paraffin). For another nine haptens, primed lymphocytes proliferated significantly more than control lymphocytes; the stimulation index (SI; ratio between [3H]methylthymidine ([3H]TdR) incorporation of lymphocytes with antigen-modified APCs and [3H]TdR incorporation of lymphocytes with APCs not modified by antigen) was 1.6-4.8 in sensitized animals whereas it was about 1.0 in control animals. Sodium dodecyl sulfate did not cause lymphocyte proliferation. The SI value in vitro was correlated with both the positive rate in vivo (r = 0.736) and the mean response score in vivo (r = 0.645). Thus, it was possible to confirm that positivity in routine experiments was a true sign of allergy. A combination of this assay and short-term animal studies would provide an efficient assessment of the allergic potential of chemicals.

Animals↗
PubMed1993

Solitary infantile myofibromatosis of bone. An immunohistochemical and ultrastructural study.

A rare case of solitary infantile myofibromatosis of bone in an 11-month-old boy is reported. Radiographically the lesion of parietal bone was round, well-circumscribed, and osteolytic with a sclerotic rim. Histologically the tumor was made up of nodules that were hyalinized or cellular and containing plump, spindle-shaped cells that were intermediate in appearance between fibroblasts and smooth-muscle cells, arranged in short bundles or whorls. Another typical feature was the presence of distended, cleft-shaped vascular spaces around the nodules. The microscopic features of this tumor were consistent with those of infantile myofibromatosis of other sites, such as the skin and deep soft tissue. The tumor cells showed immunoreactivities for vimentin and alpha-smooth muscle actin. Microfilaments with dense bodies were observed in the fibroblast-like tumor cells. In addition, many tumor cells stained for collagen type IV and were covered by incomplete external laminae, indicating infantile myofibromatosis has more advanced smooth-muscle differentiation than conventional fibromatosis.

Actins↗