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Biomedical subjects

Y Ohyama

Publications and source records attributed to Y Ohyama.

At least 91 records · Page 5Linked to original sources
PubMed1997

Quantitative evaluation of the hepatic functional reserve using technetium-99m DTPA-galactosyl human serum albumin before and after transjugular intrahepatic portosystemic shunt.

Transjugular intrahepatic portosystemic shunt (TIPS), a new therapeutic method, has been performed widely for the treatment of portal hypertension. TIPS produces a decrease in the portal blood flow to the hepatic parenchyma, which is considered to cause a reduction in hepatic functional reserve. To evaluate the changes in hepatic functional reserve after TIPS, we performed technetium-99m DTPA-galactosyl human serum algumin (99mTc-GSA) hepatic scintigraphy before and after TIPS in eight male patients, ranging in age from 54 to 72 years (mean 62.2 years). Two quantitative indices - blood clearance index (uptake ratio of the heart at 15 min to that at 3 min, HH15) and hepatic accumulation index (uptake ratio of the liver to the liver plus heart at 15 min, LHL15) - were calculated from the time-activity curves of the heart and liver. Early and late uptake constant indices (early and late KU) were also calculated from the time-activity curves of the heart and liver by means of Patlak plot. The values of HH15, LHL15 and late KU deteriorated after TIPS in all patients. Early KU (1-3 min) decreased by more than 55% in two patients who showed a poor prognosis and corresponded well with the status of the portosystemic shunt. It is concluded that 99mTc-GSA hepatic scintigraphy is a useful means of evaluating the degree to which hepatic function is compromised following TIPS. The post-TIPS alterations in HH15, LHL15 and late KU (5-10 min) reflect the changes in hepatic functional reserve, and early KU is a useful index for evaluating the degree of portosystemic shunt.

Humans↗
PubMed1997

Method for the simultaneous determination of Aconitum alkaloids and their hydrolysis products by gas chromatography-mass spectrometry in human serum.

This paper describes a newly developed method using gas chromatography-selected ion monitoring (GC-SIM) for the simultaneous determination of diester-diterpene type Aconitum alkaloids and their hydrolysis products in human serum. When the alkaloids were converted into their TMS derivatives, they produced a well defined peak on selected ion recording (SIR). Good linear response over the range of 100 pg to 7.5 ng was demonstrated for each alkaloid. When the alkaloids were spiked into human serum, good quantitative recovery was observed.

Aconitine↗
PubMed1997

Mouse beta-galactoside alpha 2,3-sialyltransferases: comparison of in vitro substrate specificities and tissue specific expression.

Four types of beta-galactoside alpha 2,3-sialyltransferase (ST3Gal I-IV) have been cloned from several animals, but some contradictory observations regarding their substrate specificities and expression have been reported. Therefore, it is necessary to concurrently analyze the substrate specificities of the four enzymes, of which the source should be one animal. Accordingly, the acceptor substrate specificities and gene expression of mST3Gal I-IV were analyzed. Since we had already cloned ST3Gal I and II, as previously reported (Lee, Y.-C. et al., Eur. J. Biochem., 216, 377-385 (1993); J. Biol. Chem., 269, 10028-10033 (1994)), the cDNAs of ST3Gal III and IV were cloned from mouse cDNA libraries. Each of the four enzymes was expressed in COS-7 cells as a recombinant enzyme fused with protein A, and applied on an IgG-Sepharose gel to eliminate endogenous sialyltransferase activity. ST3Gal I and II showed the highest activity toward Gal beta 1, 3 GalNAc (type III), very low activity toward Gal beta 1,3GlcNAc (type I), but none toward Gal beta 1,4GlcNAc (type II). ST3Gal III and IV exhibited high activity toward the type I and II disaccharides, but very low activity toward the type III one. On the other hand, asialo-GM1 (Gg4Cer) was as good a substrate for ST3Gal I and II as the type III disaccharide, though ST3Gal III and IV hardly utilized glycolipids as substrates, as indicated by in vitro experiments. Northern blot analysis revealed that enzymes of the ST3Gal-family are expressed mainly in a tissue-specific manner. The ST3Gal I gene was strongly expressed in spleen and salivary gland, and weakly in brain, liver, heart, kidney, and thymus. The ST3Gal II gene was strongly expressed in brain, and weakly in colon, thymus, salivary gland, and testis, and developmentally expressed in liver, heart, kidney, and spleen. The ST3Gal III and IV genes were expressed in a wide variety of tissues. These differences in tissue specific expression suggest the expression of each ST3Gal influences the distribution of sialyl-glycoconjugates in vivo.

Amino Acid Sequence↗
PubMed1997

Chronic blockade of nitric oxide synthesis increases urinary endothelin-1 excretion.

OBJECTIVES: Our objective was to determine the effect of nitric oxide (NO) inhibition on renal synthesis of endothelin-1 (ET-1) in vivo. DESIGN AND METHODS: Rats were administered 500 mg/l NG-nitro-L-arginine methyl ester (L-NAME) in their drinking water or its vehicle for 2 weeks (2W-L-NAME, n = 10; 2W-CONT, n = 10) or for 6 weeks (6W-L-NAME, n = 13; 6W-CONT, n = 11). We measured the levels of albumin, NO metabolites and ET-1 both in their blood and in 24 h urine samples, and determined the expression of preproET-1 messenger RNA in the renal cortex and the inner medulla. We also examined renal histology. RESULTS: L-NAME administration for 6 weeks reduced NO metabolites both in serum (21.5 versus 3.66 nmol/ml in 6W-CONT) and in urine (5.72 versus 22.53 nmol/24 h in 6W-CONT), raised the systolic blood pressure (228 versus 162 mmHg in 6W-CONT), and the increased urinary excretion of albumin (24.29 +/- 11.66 versus 0.60 +/- 0.08 mg/day in 6W-CONT) and of ET-1 (112.0 +/- 38.3 versus 35.8 +/- 4.4 pg/day in 6W-CONT). There were no significant differences between the plasma levels of ET-1 in the control and L-NAME groups. Expression of preproET-1 messenger RNA increased in the renal cortex but not in the inner medulla in the 6W-L-NAME group. Bleeding and marked arteriolar narrowing were observed in the renal cortex of the 6W-L-NAME group. CONCLUSIONS: Prolonged inhibition of NO synthesis increases urinary excretion of ET-1 and albumin without having any effect on plasma ET-1 levels. These results do not support the hypothesis that NO plays an inhibitory role in the regulation of ET-1 in the systemic circulation, although it is possible that such a role could exist in renal tissue. However, in view of the albuminuria, a more likely explanation is that increased urinary ET-1 is secondary to L-NAME-induced renal hyperfiltration injury.

Albuminuria↗
PubMed1997

16S rRNA gene sequence of Rubrobacter radiotolerans and its phylogenetic alignment with members of the genus Arthrobacter, gram-positive bacteria, and members of the family Deinococcaceae.

The nearly complete sequence of the 16S rRNA gene of an extremely highly radiotolerant bacterium, Rubrobacter radiotolerans (reclassified from Arthrobacter radiotolerans based on chemical characteristics), was determined by PCR amplification of the genomic DNA followed by cloning of the amplified gene and sequencing by the dideoxynucleotide method. The sequence was aligned with the sequences of members of the genus Arthrobacter and also with the sequences of representatives of the gram-positive bacteria having high G + C contents and the family Deinococcaceae (radioresistant micrococci and their relatives). The results of our phylogenetic analysis confirmed that R. radiotolerans is not a member of the Arthrobacter group and thus supported the previous reclassification. Moreover, although it is radioresistant and has a high G+C content, R. radiotolerans is more closely related to the gram-positive bacteria with high G+C contents than to the radioresistant members of the Deinococcaceae.

Arthrobacter↗
PubMed1997

An association between salivary gland disease and serological abnormalities in Sjögren's syndrome.

In the labial salivary glands (LSGs) of 16 primary and 18 secondary Sjögren's syndrome (SS) patients, infiltrating lymphocytes were histologically and immunohistochemically examined; also, the serum levels of rheumatoid factor, antinuclear antibodies, anti-DNA antibodies, anti-SS-A and anti-SS-B antibodies, and immunoglobulins (including IgG, IgM and IgA) were all assayed. An immunohistochemical analysis of the lymphocyte subsets in LSGs revealed that severe lymphocytic infiltration was frequently accompanied by marked B cell accumulation both in primary and secondary SS patients. Furthermore, local B cell accumulation was also closely associated with elevated levels of anti-SS-A and anti-SS-B antibodies and IgG, and this association was statistically significant in the group with primary SS but not in the group with secondary SS. Thus, local lymphocytic infiltration, especially B cell accumulation, in the salivary glands is suggested to be involved in serological abnormalities in primary SS, while complicated autoimmune diseases other than SS may also be involved in serological abnormalities in secondary SS.

Adolescent↗
PubMed1997

The mechanisms of transient hypothyroxinemia in infants born to mothers with Graves' disease.

Transient hypothyroxinemia in infants born to mothers with Graves' disease is a unique disorder first reported by us in 1988. Most mothers of these infants have had no treatment, are diagnosed as having thyrotoxicosis during the last trimester, or were not well controlled during pregnancy. These infants are believed to have transient central hypothyroidism, the mechanisms of which have not been elucidated. We measured TSH-receptor antibody activities in maternal serum and blood thyroxine (T4) (free thyroxine, FT4) and TSH levels in blood dried on filter paper at 1, 3, and 5 d of age in 114 infants born to mothers with Graves' disease. The 114 infants were retrospectively divided into three groups according to the clinical course and thyroid function data: group G, neonatal thyrotoxicosis; group T, transient hypothyroxinemia; and group E, euthyroid. In group T, the dried blood T4 (FT4) level from cord blood and/or 1 d of age blood was 6.0 +/- 2.3 microg/dL (0.92 +/- 0.52 ng/dL), a value significantly higher than that at 5 d of age (3.6 +/- 1.0 microg/dL; 0.38 +/- 0.18 ng/dL) (p = 0.025 in T4, p = 0.042 in FT4). In contrast, these levels were significantly lower at birth relative to 5 d in group G (p = 0.0001 in T4) and not significantly changed in group E. The TSH level of cord blood and/or 1-d-old blood in group T was significantly lower than that of group E (p = 0.0006). Moreover, the TSH levels in response to thyrotropin-releasing hormone were blunted in most infants in group T. Bone maturation was not delayed in group T, compared with euthyroid infants. The higher blood T4 (FT4) levels at birth, relative to 5 d in group T, suggested that the fetal T4 level was higher than that of the newborn period. The fetal T4 level might have been elevated owing to transfer of T4 from mother to fetus during the last trimester when the mother's thyroid function was elevated and consequently the fetal pituitary-thyroid axis was suppressed. Although the serum T4 (FT4) levels were decreased after birth, TSH levels were not elevated, probably because the pituitary-thyroid axis was suppressed. This may be the reason for the transient hypothyroxinemia with a normal TSH level in infants born to mothers with poorly controlled Graves' disease. Weak maternal thyroid-stimulating antibody activities and differences in sensitivity of the thyroid gland to TSH-receptor antibodies may contribute to this unique disorder.

Bone Development↗
PubMed1997

3D analysis of nystagmus during peripheral vertiginous attacks.

In order to localize the site of lesion of peripheral vertigo, 3D analysis of nystagmus during peripheral vertiginous attacks was carried out. In comparison between the three components, the horizontal component had the largest ratio in each disease. Spontaneous nystagmus was directed toward the affected side in 3 cases and to the opposite side in 15. In patients with Menière's disease (MD), all subjects had horizontal and torsional components and had almost the same slow phase velocity in these two components. In patients with vestibular neuritis (VN) and Hunt's syndrome (HS), nystagmus was directed toward the opposite side. Furthermore, in VN, all subjects had an upward component, in addition to horizontal and torsional components. Inferring the focus from the character of nystagmus, it is speculated that the pathological changes are located in the entire inner ear in MD, whereas in VN the lesion is located in the horizontal and anterior semicircular canal or the superior vestibular nerve.

Adult↗
PubMed1997

[Scatter correction with an off-peak triple energy window method in thallium-201 imaging].

For scatter correction using the triple energy window (TEW) acquisition in 201Tl imaging, we propose an off-peak TEW (OFPTEW) method. This OFPTEW method employs a wide main energy window of 34 keV centered at 73 keV and two 5.1 keV sub-energy windows and uses the scatter correction factor of 0.55. To assess scatter correction using the OFPTEW method in 201Tl imaging, phantom studies for planar and SPECT imaging were performed and the data with the OFPTEW method were compared with those by the conventional TEW method using the trapezoidal formula with the 20% main energy window centered at 70 keV and two 4.9 keV sub-energy windows. The planar images corrected by both methods were visually similar. The OFPTEW method, however, estimated the true primary counts and the contrast value in the cold lesion accurately, while the conventional TEW method underestimated the primary counts by 30% and gave wrong contrast values. For the myocardial SPECT imaging, the short-axis images by both methods were very similar, but the images by the OFPTEW method had 1.46 times more counts than those corrected by the conventional TEW method. In conclusion, the OFPTEW method can correct scatter in 201Tl imaging accurately and increase the primary counts effectively compared with the conventional TEW method.

Phantoms, Imaging↗
PubMed1997

[Experimental study on the location of energy windows for scatter correction by the TEW method in 201Tl imaging].

To investigate validity of scatter correction by the TEW method in 201Tl imaging, we performed an experimental study using the gamma camera with the capability to perform the TEW method and a plate source with a defect. Images were acquired with the triple energy window which is recommended by the gamma camera manufacturer. The result of the energy spectrum showed that backscattered photons were included within the lower sub-energy window and main energy window, and the spectral shapes in the upper half region of the photopeak (70 keV) were not changed greatly by the source shape and the thickness of scattering materials. The scatter fraction calculated using energy spectra and, visual observation and the contrast values measured at the defect using planar images also showed that substantial primary photons were included in the upper sub-energy window. In TEW method (for scatter correction), two sub-energy windows are expected to be defined on the part of energy region in which total counts mainly consist of scattered photons. Therefore, it is necessary to investigate the use of the upper sub-energy window on scatter correction by the TEW method in 201Tl imaging.

Phantoms, Imaging↗
PubMed1997

Immunosuppressive drugs inhibit the production of interleukin-6 and interleukin-8 in cultured cardiac myxoma cells.

Cardiac myxoma cells produce large amounts of interleukin (IL)-6 and IL-8. To determine whether immunosuppressive agents could be used to treat cardiac myxoma, we tested the effects of dexamethasone and three of the newer second-generation immunosuppressive drugs, cyclosporin A, tacrolimus, and deoxyspergualin, on the production of IL-6 and IL-8 in these cells. Cultured cardiac myxoma cells were used as in vitro model of cardiac myxoma. Cells were tested for 24 hours with 10(-7) M dexamethasone, 10(-6) M cyclosporin A, 10(-8) M tacrolimus, and 10(-6) M 15-deoxyspergualin, with aliquots of conditioned medium being assayed for cytokine levels at 0, 6, 12, and 24 hours. Cardiac myxoma cells isolated from 4 patients all produced quantities of IL-6 and IL-8. The concentrations of IL-6 in the medium after 7 days in culture ranged from 79,000 to 2,740,000 pg/ml, and the concentrations of IL-8 ranged from 40,000 to 1,000,000 pg/ml. Exposure of cyclosporin A and dexamethasone almost completely inhibited the production of IL-6 and IL-8 after 24 hours of treatment. Tacrolimus inhibited the production of both cytokines by 55%, while 15-deoxyspergualin reduced IL-6 levels by 24% and IL-8 levels by 48% after separate 24 hour treatments. These results suggest that these newer immunosuppressive agents may be useful in reducing the production of IL-6 and IL-8 in patients with cardiac myxoma.

Aged↗
PubMed1997

High-salt effects on the structure and damage of chromosomal DNA in Halobacterium salinarium, an extremely halophilic bacterium.

High concentration salt effects on the structure and radiation-induced damages of DNA were studied to elucidate the biochemical mechanism of the resistance of halophilic H. salinarium against DNA damaging agents. High concentration of KCl did not induce significant conformational changes in H. salinarium chromosomal DNA, but exhibited an extensive protective effect on the radiation-induced single-strand breaks of plasmid DNA.

Chromosomes, Bacterial↗
PubMed1997

Mechanisms of the genotoxic effects associated with 5-formyluracil: effect of exogenous 5'-formyl-2'-deoxyuridine.

E. coli HB101 harboring plasmid pUC19 was grown in the presence of 5-formyl-2'-deoxyuridine (fdU) to evaluate the genotoxic and cytotoxic potentials associated with this DNA lesion. Cell growth was inhibited by fdU in a concentration-dependent manner, but increased mutation was not observed in the lacZ(alpha) gene of pUC19. The lack of the mutagenic effect was attributed to poor utilization of fdU as a substrate by thymidine kinase, which converts exogenous thymidine analogs to the corresponding 5'-monophosphates in the salvage pathway.

Cell Division↗
PubMed1996

Functional assessment of two vitamin D-responsive elements in the rat 25-hydroxyvitamin D3 24-hydroxylase gene.

Two vitamin D-responsive elements (VDRE-1 and VDRE-2) were recently identified in the 5'-upstream region of the rat 25-hydroxyvitamin D3 24-hydroxylase gene at -151/-137 and -259/-245, respectively. We studied the transcriptional regulation of this gene by vitamin D by means of mutational analysis. Introducing mutations into VDRE-1 and VDRE-2 in the native promoter -291/+9 reduced vitamin D-dependent chloramphenicol acetyltransferase activity by 86 and 41%, respectively. Mutation of the direct repeat -169/-155 located at 3 base pairs upstream of VDRE-1 also caused 50% decrease of chloramphenicol acetyltransferase activity. Connection of the element -169/-155 to VDRE-1 enhanced the vitamin D responsiveness of VDRE-1 5-fold through the heterologous beta-globin promoter. The fragment -291/-102 containing the two VDREs showed two shifted bands in the presence of the vitamin D receptor and retinoid X receptor in gel retardation analysis, and the appearance of the slower migrating band indicates that two sets of receptor complexes bind to this fragment simultaneously. These results demonstrate that VDRE-1 is a stronger mediator of vitamin D function than VDRE-2 due to the presence of the accessory element -169/-155 located adjacent to VDRE-1, although VDRE-2 exhibits a smaller dissociation constant for the vitamin D receptor-retinoid X receptor complex than VDRE-1.

Animals↗
PubMed1996

Cytokine messenger RNA expression in the labial salivary glands of patients with Sjögren's syndrome.

OBJECTIVE: To characterize the initiation and progress of localized autoimmune damage in Sjögren's syndrome (SS), an autoimmune disease that is also considered to be a lymphoaggressive disorder, by examining the pattern of cytokine production at the site of autoimmune damage. METHODS: Using a polymerase chain reaction-based method, cytokine messenger RNA (mRNA) expression in the labial salivary glands of 15 patients with SS was investigated. In addition, the infiltrating lymphocytes in the labial salivary glands were examined immunohistochemically. RESULTS: Messenger RNAs of Th1 cytokines, such as interleukin-2 (IL-2) and interferon-gamma, were consistently detected in all patients, while Th2 cytokine mRNAs, such as IL-4 and IL-5, were detected in some cases, in association with strong B cell accumulation in the labial salivary glands. Other cytokine mRNAs produced by a variety of cell types, including IL-10, IL-6, and transforming growth factor beta (TGF beta), were also consistently detected in all patients, while IL-12 mRNA was detected in some of the patients. CONCLUSION: These results suggest that Th1 cytokines, as well as IL-10, IL-6, and TGF beta, are essential in the induction and/or maintenance of SS, while Th2 cytokines are involved in the progression of the disease process, especially local B cell activation.

Adult↗
PubMed1996

T cell receptor V alpha and V beta gene usage by tumour-infiltrating lymphocytes in oral squamous cell carcinoma.

Oral squamous cell carcinomas (SCC) are often infiltrated by a large number of T lymphocytes. To clarify the nature of the tumour-infiltrating lymphocytes (TIL), we examined T cell receptor (TCR) V alpha and V beta gene usage by TIL and peripheral blood mononuclear cells (PBMC) obtained from 10 patients with oral SCC. We obtained RNA from TIL and PBMC, synthesized complementary DNA, and used the polymerase chain reaction (PCR) method with a panel of primers specific for the V gene segment subfamily (V alpha 1-18/V beta 1-20). We thus found that TIL showed more restricted usage of V beta gene families in contrast to PBMC of the same patients while two unique V beta gene (V beta 6 and V beta 5.2) segment transcripts were overexpressed in the TIL of more than half of the patients. On the other hand, no major difference was observed in the V alpha gene usage between the TIL and PBMC of most patients. To characterize these T cell subpopulations with unique V beta gene segment transcripts further, we sequenced the complementarity-determining region 3 in V beta 6-C beta and V beta 5.2-C beta PCR products derived from TIL and PBMC of two selected patients in each case. Although no usage of the conserved amino acid sequence by TIL was detected, the frequent use of V beta 6/J beta 1.1 in one patient and the V beta 6/J beta 2.7 gene segments in another patient was observed. Regarding the V beta 5.2 transcripts, obtained from the other two patients, no preferential usage of specific J beta gene segments by TIL was observed. These results suggest that the unique T cell populations are amplified in patients with oral SCC, possibly as a consequence of an in situ immune reaction.

Adult↗