Biomedical subjects

S Okada

Publications and source records attributed to S Okada.

At least 289 records · Page 16Linked to original sources

PubMed1999

Differential diagnosis of left ventricular mural thrombi by myocardial contrast echocardiography: a preliminary study.

Two-dimensional echocardiography has become the procedure of choice to diagnose left ventricular mural thrombi. However, small or flat thrombi may be difficult to distinguish from myocardium. The spatial distribution of the ventricular myocardial blood flow can be imaged with myocardial contrast echocardiography (MCE). The authors presumed that the absence of arterial supply to a fresh thrombus may allow MCE to distinguish between thrombus and myocardium. In the 2 cases presented here, MCE was performed with the same technique as that used for the purpose of visualization of myocardial perfusion; as a result, an apical mural thrombus, indistinct from myocardium before MCE, was visualized as a contrast defect during imaging. Conversely, myocardium that mimicked a thrombus was imaged by MCE as a contrast-opacified area. These findings suggest that MCE after reperfusion therapy is useful to distinguish mural thrombi from myocardium.

Aged↗

PubMed1999

Melatonin inhibits the central sympatho-adrenomedullary outflow in rats.

Central effects of melatonin on the sympatho-adrenomedullary outflow were investigated in urethane-anesthetized rats. In the intact animals, intracerebroventricularly (i.c.v.) administered interleukin-1beta (IL-1beta) (100 ng/animal) slightly, but significantly, elevated the plasma level of noradrenaline (NA), but not the level of adrenaline (Ad). Melatonin (100 microg/animal, i.c.v.) did not modulate the effects of IL-1beta on plasma levels of catecholamines. In the pinealectomized animals, however, the same dose of IL-1beta markedly elevated plasma levels of both Ad and NA, and the elevation of Ad was more potent than that of NA. In these pinealectomized animals, the serum level of melatonin was significantly lower than that in the sham-operated control animals. Furthermore, the IL-1beta-induced elevations of plasma catecholamines in these pinealectomized animals were attenuated by i.c.v. administered melatonin. These results suggest that melatonin plays an inhibitory role in the central regulation of sympatho-adrenomedullary outflow in rats.

Adrenal Medulla↗

PubMed1999

Mutation induction and RBE of low energy neutrons in V79 cells.

We have examined the neutron energy dependency of cell killing and mutation induction at the hprt locus in Chinese hamster V79 cells. Monoenergetic neutrons at 0.32, 0.57, and 1.2 MeV were generated at the Hiroshima University Radiobiological Research Accelerator (HIRRAC) Facility, and were used to irradiate cells. The variation in RBE with neutron energy for the end points of cell survival and hprt mutation induction was observed. When compared to 137Cs gamma-rays, all neutron energies were more effective at both cell killing and induction of mutation. Over the range of the neutron energies examined, we found that cytotoxicity increased as the energy decreased from 1.2 to 0.32 MeV. In comparison to gamma-rays, RBEs for cell lethality at 10% survival were 5.7, 6.7, and 7.6 for 1.2, 0.57, and 0.32 MeV, respectively. Mutation induction, on the other hand, was highest at 0.57 MeV with a gradual decrease at 1.2 and 0.32 MeV. RBEs for mutation induction were 9.7, 19.4, and 13.9 for 1.2, 0.57, and 0.32 MeV neutrons. We isolated independent V79 cell mutants at the hprt locus from untreated and neutron-exposed cells and determined the genetic changes underlying the mutation by multiplex polymerase chain reaction (PCR)-based exon deletion analysis. Preliminary results are suggestive of a specific relationship between deletion pattern and neutron energy.

Animals↗

PubMed1999

Enhancement of swimming endurance in mice by highly branched cyclic dextrin.

We investigated the ergogenic effect in mice of administering highly branched cyclic dextrin (HBCD), a new type of glucose polymer, on the swimming endurance in an adjustable-current swimming pool. Male Std ddY mice were administered a HBCD, a glucose solution or water via a stomach sonde 10 min before, 10 min after or 30 min after beginning swimming exercise, and were then obliged to swim in the pool. The total swimming period until exhaustion, an index of the swimming endurance, was measured. An ergogenic effect of HBCD was observed at a dose of 500 mg/kg of body weight, whereas it had no effect at a dose of 166 mg/kg of body wt (p < 0.05). The mice administered with the HBCD solution 10 min after starting the exercise were able to swim significantly longer (p < 0.05) than the mice who had ingested water or the glucose solution. The rise in mean blood glucose level in the mice administered with HBCD, which was measured 20 min after starting swimming, was significantly lower (p < 0.05) than that in the mice administered with glucose, although it was significantly higher (p < 0.05) than that in the mice administered with water. The mean blood insulin rise in the mice given HBCD was significantly lower (p < 0.05) than that in the mice given glucose. The mice administered with HBCD 30 min after starting the exercise swam significantly longer (p < 0.05) than the mice who had ingested water, although the enhancement of swimming time was similar to that of the glucose-ingesting mice. The gastric emptying rate of the HBCD solution was significantly faster (p < 0.05) than that of the glucose solution. However, this glucose polymer must have spent more time being absorbed because it has to be hydrolyzed before absorption, reflecting a lower and possibly longer-lasting blood glucose level. We conclude that the prolongation of swimming endurance in mice administered with HBCD depended on its rapid and longer-lasting ability for supplying glucose with a lower postprandial blood insulin response, leading to a delayed onset of fatigue.

Animals↗

PubMed1999

Permeation of hesperidin glycosides across Caco-2 cell monolayers via the paracellular pathway.

The intestinal permeability to hesperidin glycosides was investigated by using a cultured monolayer of Caco-2 as a model for the small intestinal epithelium. Hesperidin glycosides were added to the apical side of the monolayer, and the substances that permeated to the basolateral side were determined by HPLC. Whereas hesperidin did not permeate across the Caco-2 monolayer, probably owing to its low solubility, the hesperidin glycosides did permeate. The transepithelial transport of hesperidin glycosides occurred in time- and dose-dependent manners. The transport was observed to be energy-independent, and was inversely correlated with the transepithelial electrical resistance (TEER) of the monolayer. These results suggest that hesperidin glycosides permeate across the Caco-2 cell monolayer via the paracellular pathway.

Caco-2 Cells↗

PubMed1999

Insulin and EGF receptors integrate the Ras and Rap signaling pathways.

Ras is a low molecular weight (Mr 21,000) GTP binding protein that plays an essential role in cell proliferation and differentiation. Mutations that result in constitutive activation of Ras are associated with several types of neoplastic tissue in mammals and expression of these alleles into cultured fibroblasts results in cellular transformation. Opposing the Ras activation pathway, the low molecular GTP binding protein Rap was originally observed to revert or suppress the transformed phenotype in Ki-Ras-transformed fibroblasts. This apparent antagonism between Ras and Rap function may reflect the ability of Rap and Ras to interact with the same downstream effectors, since these proteins share identical sequences within their respective effector domains. Although the precise molecular details remained to be established, there is a substantial similarity in the upstream signaling mechanisms that regulate both Ras and Rap activation. Ras GTP binding is stimulated upon the targeting of the Ras guanylnucleotide exchange factor SOS to the plasma membrane location of Ras. The carboxyl terminal domain of SOS contains a proline-rich regions that directs its association with the SH3 domains of the small adapter protein, Grb2. Similarly, the formation of active GTP-bound Rap results from the specific interaction with the Rap guanylnucleotide exchange factor C3G which specifically associates with the central SH3 domain of the small adapter protein, CrkII. Thus, efficient regulation of receptor tyrosine kinase downstream signaling events require the coordinate interplay of these two pathways.

Animals↗

PubMed1999

Regional left ventricular motion during early filling phase in patients with right ventricular pressure overload.

Global left ventricular (LV) diastolic function has been reported to be disturbed under conditions of right ventricular pressure overload (RVPO). However, from the standpoint of regional wall motion, only a little information related to the mechanism of LV diastolic dysfunction is available. Eight patients with RVPO and 7 healthy volunteers were investigated using tagged cine magnetic resonance imaging. Regional diastolic fraction (RDF) was determined in 4 segments (anterior, lateral, inferior, and septal) in the mid-ventricular short axis section and in 2 segments (septal and lateral) in the 4-chamber section. A heterogeneity index was obtained from the RDFs of the short axis section. In the RVPO group, in both short axis and 4-chamber sections, the RDF of the septal segment was depressed, and it showed an inverse correlation with the right-to-left ventricular systolic pressure (RV/LV) ratio (r = -0.74, p < 0.05) in the short axis section. In the 4-chamber section, the RDF was lower in the septal segment than in the lateral segment (p < 0.05). The heterogeneity index in the RVPO group was greater than that in the control group (p < 0.01). The index correlated positively with the RV/LV ratio (r = 0.77, p < 0.05). The altered regional diastolic motion results in increased heterogeneity in regional diastolic motion.

Adolescent↗

PubMed1999

The significance of NSE and CEA as a differentiation marker for the cellular heterogeneity of small cell lung cancer.

Neuron-specific enolase (NSE) and carcinoembryonic antigen (CEA) levels in the culture supernatant of the 65 pulmonary carcinoma cell lines: Small cell lung cancer (SCLC) 18, large cell carcinoma 14, squamous cell carcinoma 14, adenocarcinoma 14 and adenosquamous cell carcinoma 5, were measured by a radioimmunoassay (RIA). The mean value of NSE was 30.8+/-22.4 ng/ml and 9.2+/-8.7 ng/ml in SCLC and non-SCLC, respectively. The mean value of CEA was 15.1+/-20.9 ng/ml and 26.6+/-72.3 ng/ml in SCLC and non-SCLC, respectively. A significant difference in NSE levels was obtained between SCLC cell lines and non-SCLC cell lines. In SCLC cell lines, a significant inverse proportional correlation was observed between NSE and CEA levels. The CEA production tended to be higher in cells with low levels of NSE than in those with high NSE production. With respect to correlation between marker production and growth characteristics of SCLC cells in vitro, significantly higher NSE and lower CEA levels were found in cells growing with floating colony or neurite like characteristics (classic cell type) than those in cells with epithelial or intermediate growth characteristics (variant cell type). A significant positive correlation between NSE levels and the survival periods was found in follow-up studies of 10 patients who underwent surgery with complete resection of the primary tumor. All of 4 long term survivors over 3 years after surgery had significantly high NSE and relatively low CEA producing tumors. The relationship of these markers to clinical status of the patient suggests that an analysis for correlation of NSE and CEA levels in SCLC patients may be useful to discriminate between a pure neuroendocrine SCLC tumor and a mixed small cell/large cell tumor, and in monitoring therapeutic effect and prognosis of each patient.

Adult↗

PubMed1999

Primary aldosteronism with aldosterone-producing adrenal adenoma in a pregnant woman.

A 30-year-old pregnant woman complained of muscle weakness at 29 weeks' gestation. She was hypertensive with severe hypokalemia. Lower plasma renin activity and higher aldosterone level than the normal values in pregnancy suggested primary aldosteronism. A cesarean delivery was performed at 31 weeks' gestation because of pulmonary congestion. The neonatal course was uncomplicated. The laparoscopic adrenalectomy for a 2.0-cm right adrenal adenoma resulted in normalizing of her blood pressure and serum potassium level. Although primary aldosteronism is rare, especially during pregnancy, it should be always considered as one of etiologies of hypertension in pregnancy.

Adrenal Cortex Neoplasms↗

PubMed1999

Single cell analysis of T cells infiltrating labial salivary glands from patients with Sjögren's syndrome.

Sjögren's syndrome (SS) is an autoimmune disease characterized by lymphocytic infiltration into the lacrimal and salivary glands leading to symptomatic dry eyes and mouth. To analyze the function of T cells infiltrating the labial salivary glands, we analyzed T cell receptor (TCR) beta and alpha chains, the expression of various cytokine mRNAs, and apoptosis associated genes in predominant TCR BV2+ T cells in the labial salivary glands of patients with SS at the single cell level. TCR BV2+ T cells in the labial salivary glands were sorted as single cells by flow-cytometry, and then examined by a single cell polymerase chain reaction (PCR). We isolated 18 TCR BV2+ T cell clones from three patients with SS. In six clones, there were highly conserved amino acid motifs (RDxG, GNT, QGxxQETQ) in the CDR3 region of the TCR beta chain. Three of the six clones showed conserved amino acids (EDxTG, or ExxTG) in the CDR3 region of the TCR alpha chain, suggesting restricted T cell epitopes. All TCR BV2+ clones expressed IL-2 mRNA, and six clones were able to produce IL-4, indicating that the cells were Th0 type T cells. All TCR BV2+ clones in the labial salivary glands were CD4+ T cells, and ten clones overexpressed Fas antigen at the mRNA level. In contrast, only one clone expressed Fas-ligand (Fas-L) mRNA, and neither perforin nor granzyme A/B was expressed. In conclusion, these findings support the notion that TCR BV2+ T cells that infiltrate labial salivary glands recognize restricted epitopes and function as CD4+ Th0 type T cells in the induction phase of autoimmunity.

Amino Acid Sequence↗

PubMed1999

[Connatal type of Pelizaeus-Merzbacher disease: a case report].

Pelizaeus-Merzbacher disease (PMD) is a hereditary disorder with myelin dysplasia in the central nervous system. The connatal type is a more severe form compared to the classical type and shows developmental arrest or deterioration, nystagmus, spasticity, and/or convulsions in the neonatal period. A 1 1/4-year-old Japanese boy diagnosed as connatal type PMD is reported here. Soon after his birth, he demonstrated horizontal and rotatory nystagmus and opisthotonic posture. At the age of 10 months, he had difficulty in feeding. At the age of 1 year, he presented more severe opisthotonic posture and frequent vomiting. He showed deterioration in gross motor development. His chromosome analysis showed a normal male karyotype. Electroencephalogram did not show a sleep spindle. Auditory evoked brainstem responses (ABR) showed only wave I on both sides. Visual evoked potentials (VEP) showed prolongation of latencies. These results were compatible with PMD. Nuclear magnetic resonance imaging (MRI) demonstrated in the white matter of cerebrum and brainstem no high intensities on T1-weighted images and diffuse high intensities on T2-weighted images. Such absence of myelination including the brainstem was characteristic to the connatal type PMD. The diffuse disturbance of myelination appeared to correlate with the severity of clinical symptoms.

Brain↗

PubMed1999

[A case of hypocomplementemic mesangial proliferative glomerulonephritis progressing to focal membranoproliferation without aggravation of urinalysis].

We reported a 14-year-old boy with hypocomplementemic mesangial proliferative glomerulonephritis progressing to focal membranoproliferation without aggravation of urinalysis. He was pointed out as having asymptomatic hematuria by a school urinalysis screening, and revealed mild hematuria and proteinuria (not nephrotic). The laboratory data showed severe hypocomplementemia and high titers of antistreptolysin O (ASO) and antistreptokinase (ASK). A renal biopsy specimen obtained 2 months after the onset showed diffuse mesangial proliferation, and did not display any characteristic changes in membranoproliferative glomerulonephritis by either light or electron microscopy. After eight months of observation, a second renal biopsy was performed in order to examine morphological changes, because severe hypocomplementemia, mild hematuria and proteinuria had persisted. The second biopsy specimen showed C3 deposition with a mesangiocapillary pattern detected by immunofluorescence microscopy and diffuse mesangial proliferation by light microscopy. In some glomeruli, electron microscopy showed focal mesangial interposition, which was considered to be a histological feature of focal membranoproliferative glomerulonephritis. Intravenous methylprednisolone pulse therapy and subsequent glucocorticoid administration (60 mg of prednisolone every other day) was performed. The serum complement level was elevated just after the methylprednisolone pulse therapy, but fell to the previous value within 2 months. The hypocomplementemia, even if proteinuria and hematuria were mild, indicated the existence of glomerular change in this case.

Adolescent↗

PubMed1999

[Susceptibilities of bacteria isolated from patients with lower respiratory infectious diseases to antibiotics (1997)].

The bacteria isolated from the patients with lower respiratory tract infections were collected by institutions located throughout Japan, since 1981. Ikemoto et al. have been investigating susceptibilities of these isolates to various antibacterial agents and antibiotics, and analyzed some characteristics of the patients and isolates from them each year. Results obtained from these investigations are discussed. In these 17 institutions around the entire Japan, 512 strains of presumably etiological bacteria were isolated mainly from the sputa of 440 patients with lower respiratory tract infections during the period from October in 1997 to September in 1998. MICs of various antibacterial agents and antibiotics were determined against 100 strains of Staphylococcus aureus, 81 strains of Streptococcus pneumoniae, 85 strains of Haemophilus influenzae. 71 strains of Pseudomonas aeruginosa (non-mucoid strains), 27 strains of Pseudomonas aeruginosa (mucoid strains), 33 strains of Moraxella subgenus Branhamella catarrhalis, 17 strains of Klebsiella pneumoniae etc., and the susceptibilities of these strains were assessed except for those strains that died during transportation. S. aureus strains for which MICs of oxacillin (MPIPC) were higher than 4 micrograms/ml (methicillin-resistant S. aureus: MRSA) accounted for 55.0%. The frequency of the drug resistant bacteria decreased comparing to the previous year's 67.3%. Arbekacin (ABK) and vancomycin (VCM) showed the most potent activities against MRSA. Imipenem (IPM) and panipenem (PAPM) of carbapenems showed the most potent activities with MIC80S of 0.063 microgram/ml against S. pneumoniae. The frequency of penicillin (PC)-intermediate S. pneumoniae (PISP)+PC-resistant S. pneumoniae (PRSP) had decreased gradually, that is, in 1995 the frequency of it was 40.3%, but that was 30.9% in 1997. Against H. influenzae and M.(B.) catarrhalis, all the drugs showed good activities. But the sensitive strains of them against ceftazidime (CAZ) had decreased in 1997, compared those in 1995 and 1996. Meropenem (MEPM), IPM and tobramycin (TOB) showed the most potent activity against P. aeruginosa (mucoid strains). And TOB and ciprofloxacin (CPFX) showed the most potent activities against P. aeruginosa (non-mucoid strains). All drugs except ampicillin (ABPC) were more active against K. pneumoniae in 1997 than that in 1996. Also, we investigated year to year changes in the characteristics of patients, their respiratory infectious diseases, and the etiology. The examination of age distribution indicated that the proportion of patients with ages over 70 years was 45.5% of all the patients showing a slight increase year by year. About the proportion of diagnosed diseases, not so particular changes were recognized as follows: Bacterial pneumonia and chronic bronchitis were the most frequent with 33.6% and 29.1%, respectively. Number of strains isolated from patients before administration of antibiotics were more than those after administration of them in chronic bronchitis, but these had reversed in bacterial pneumonia. The tendency in bacterial pneumonia had been acknowledged since 1995. The increase of S. aureus and P. aeruginosa (both mucoid and non-mucoid strains) isolated after administration of antibiotics, has suggested the decrease of the susceptibility of these strains against antibiotics. Administration of antibiotics has changed the results of the frequency of isolation of bacterial species. Bacterial isolations before administration of antibiotics were as follows: S. pneumoniae 24.5%, H. influenzae 21.4%, S. aureus 18.4% and P. aeruginosa 12.2%. The frequencies of S. aureus decreased after antibiotics administration over 15 days, but the frequencies of P. aeruginosa was not affected. The frequencies of P. aeruginosa was 47.8% after administration over 15 days. From patients administered antibiotics of penicillins and cephems. S. aureus was mainly detected with 31.7-58.3%, and from patients administere

Adult↗

PubMed1999

A single cell analysis of TCR AV24AJ18+ DN T cells.

The T-cell receptor (TCR) BV gene of human TCR AV24+ double-negative (DN) T cells, a novel subset of natural killer (NK) T cells, was investigated by single-cell sorting and single-cell polymerase chain reaction (PCR) methods. Seven of eleven TCR AV24+ DN T-cell clones utilized TCR BV8, three BV9, and one BV6. Six of seven TCR AV24/BV8+ DN T-cell clones had identical TCR beta and alpha chains, indicating that they were the same clone. All three TCR AV24/BV9+ DN T-cell clones also demonstrated the same amino acids in the CDR3 region. These findings strongly suggest that the usage of TCR beta and alpha chains on TCR AV24+ DN T cells is extremely restricted, supporting the notion that these cells recognize highly limited T-cell epitopes on antigens. All TCR AV24+ clones expressed the NKR-P1A mRNA, and so were true NK T cells. IL-2 and IL-4 mRNAs were detected in all clones, suggesting that the majority of these cells were Th0-type T cells. Six clones overexpressed Fas-ligand (Fas-L) mRNA and Fas antigen was detected on all clones at the mRNA level. In conclusion, TCR AV24+ DN T cells might recognize restricted T-cell epitopes on antigens and function as Th0-type T cells, inducer cells to Th1- or Th2-type T cells (regulatory T cells), and as Fas-L-positive cytolytic T cells.

Amino Acid Sequence↗

PubMed1999

Proton MR spectroscopy of Sjögren-Larsson's syndrome.

We performed single-voxel proton MR spectroscopy (1H-MRS) in two children with Sjögren-Larsson's syndrome (SLS). Both patients showed two abnormal spectral peaks at 1.3 ppm and 0.9 ppm that were obtained with short echo times. These two abnormal spectral peaks were seen in high-intensity areas on T2-weighted images and also in basal ganglia of normal intensities. 1H-MRS may be useful for establishing the diagnosis and investigating the natural history of SLS, and for evaluating the efficacy of therapeutic approaches to SLS.

Aldehyde Oxidoreductases↗

PubMed1999

[Evaluation of molecular weight of hyaluronate preparations by size-exclusion chromatography].

Hyaluronate (HA), a glycosaminoglycan polysaccharide, has been used as a biomedical polymer to treat osteoarthritis by intra-articular injections and in ophthalmic surgery, such as anterior segment surgery. In this study, the molecular weight (MW) of HA preparations was estimated by size-exclusion chromatography (SEC), using HA and pullulan fractions as molecular weight standards, and the MW values obtained were compared to those obtained with a low angle laser light scattering detector (LALLS). The results showed that the universal calibration with pullulan as the standard is useful for HA preparations. The conditions of SEC for HA were also investigated, and the results suggested that a high ionic strength and low flow rate of the eluent were preferable for high molecular weight HA preparations.

Chromatography↗

PubMed1999

[Triamcinolone Acetonide Reference Standard (Control 981) of National Institute of Health Sciences].

The raw material of triamcinolone acetonide was examined for preparation of the "Triamcinolone Acetonide Reference Standard (Control 981)". The analytical data obtained were: melting point, 289 degrees C (decomposition); UV spectrum, lambda max of 238 nm; IR spectrum, same as that of the Triamcinolone Acetonide Reference Standard (Control 834); optical rotation, [alpha]D20 = +106.8 degrees; thin-layer chromatography, no impurities detected; high-performance liquid chromatography, total amount of impurities less than 0.4%; loss on drying, 1.3%; assay by HPLC, 100.1%. Based on the above results, the raw material was authorized as the Triamcinolone Acetonide Reference Standard (Control 981) of the National Institute of Health Sciences.

Government Agencies↗

PubMed1999

[Triamcinolone Reference Standard (Control 981) of National Institute of Health Sciences].

The raw material of triamcinolone was examined for preparation of the "Triamcinolone Reference Standard (Control 981)". The analytical data obtained were: melting point, 246 degrees C (decomposition); UV spectrum, lambda max of 239 nm and specific absorbance in methanol at 289 nm of 394; IR spectrum, specific absorptions at 3462, 1716, 1659, 1615, 1604, 1132 and 1061 cm-1; optical rotation, [alpha]D20 = +69.7 degrees; high-performance liquid chromatography, five impurities detected and amount of each impurity estimated to be less than 0.6% and total amount of impurities less than 1.4%; loss on drying, 0.24%. Based on the above results, the raw material was authorized as the Triamcinolone Reference Standard (Control 981) of the National Institute of Health Sciences.

Government Agencies↗