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Biomedical subjects

X Yao

Publications and source records attributed to X Yao.

At least 127 records · Page 7Linked to original sources
PubMed1997

[Light microscopic observation of bone interface of titanium-coated 317L plate screw].

The observational results of bone interface of titanium-coated 317L plate screw and 317L plate screw under light microscope are reported in the present paper. Osseointegration was formed in both kinds of screws after implanting. In the titanium-coated 317L plate screw group, the inflammatory reaction was slighter, the new bone formed earlier in the interface and the bone was combined with the metal tightly, whereas in the uncoated 317L plate screw group, the relationship between the bone and metal was only a state of contact. These indicate that the bone interface and tissue compatibility of titanium-coated 317L plate screw may be better than that of the 317L plate screw.

Animals↗
PubMed1997

[Toxic studies on various processed products of Fructus Psoraleae].

Toxic studies on Fructus Psoraleae (FP) and its processed products are carried on. LD50 is 37.7 +/- 0.54 g crude drug/kg in oral administration of raw FP in comparison with 43.25 +/- 6.1/kg in that of Salt-bake one in mice. When 5.0 g/kg is given by oral for 14 days, the wet weight of testicles, preputial galnds, prostate and semianl vesicle is decreased in raw FP and its stir-bake tested groups. The wet weight of preputial glends, prostate, seminal vesicle in Lei Gong's Procession group, or prostate, and seminal vesicle in salt-steam group is also decreased to a certain extent. But no significant change on the weight of those sex organs is found in liquor-bake or salt-bake procession group, The glomerulal cell hyperplasia and cloudy swelling of renal tubules are induced by administration of raw FP in pathological examination.

Animals↗
PubMed1997

Effects of methylprednisolone and cyclophosphamide pulse therapy on renal infiltrating cells in patients with crescentic glomerulonephritis.

OBJECTIVE: To investigate the effects of pulse methylprednisolone (MP) and monthly intravenous cyclophosphamide (CTX) therapy (MP + CTX) on renal infiltrating cells in patients with rapid progressive glomerular nephritis (RPGN). METHODS: Twelve patients with RPGN (> 50% crescents) were given MP + CTX therapy and received repeated renal biopsies within 4 to 12 weeks after MP + CTX treatment. Seven were diagnosed as type II RPGN, including one case of IgA nephropathy, 2 cases of idiopathic RPGN and 4 cases of lupus nephritis and five were diagnosed as type III RPGN, including 2 cases of idiopathic RPGN and 3 cases of vasculitis. The changes of infiltrating CD4+, CD8+, CD68+ and proliferating cell nuclear antigen-PCNA+ cell levels were determined by four PAP method in glomeruli and interstitium. RESULTS: In the patients before MP + CTX therapy, there were higher levels of infiltrating CD4+ and CD8+ cells (306 +/- 118 and 223 +/- 98.4Num/mm2) in renal interstitium, CD68+ cells (17.2 +/- 9.95 Num/G) in glomeruli and (1120 +/- 229 Num/mm2) in interstitium, and PCNA+ cells (7.56 +/- 3.57 Num/G) in glomeruli and (17.6 +/- 6.85 Num/mm2) in interstitium as compared with those in the patients after MP + CTX therapy (CD4+/CD8+ cells were 171 +/- 87.5/121 +/- 38.4 Num/mm2, CD68+ cells were 9.04 +/- 4.33 Num/G and 600 +/- 107 Num/mm2, and PCNA+ cells were 2.04 +/- 1.43 Num/G and 9.40 +/- 4.45 Num/mm2). These changes were associated with improving renal dysfunctions (the levels of serum creatinine and proteinuria decreased gradually from 766 +/- 356 to 284 +/- 192 mumol/L and 2.60 +/- 1.46 to 1.29 +/- 0.85 g/day). CONCLUSIONS: Our data indicate that the renal infiltrating cells may play an important role in renal injury in patients with RPGN. The effects of MP + CTX therapy on improving renal dysfunctions may partially contribute to its amelioration of infiltrating cells in renal tissues. The degrees of CD4+, CD68+, and PCNA+ cells in the kidney may be useful indicators of MP + CTX therapy for RPGN.

Adult↗
PubMed1996

Dynamical Signature of the Mott-Hubbard Transition in Ni(S,Se)2

The transition metal chalcogenide Ni(S,Se)2 is one of the few highly correlated, Mott-Hubbard systems without a strong first-order structural distortion that normally cuts off the critical behavior at the metal-insulator transition. The zero-temperature (T) transition was tuned with pressure, and significant deviations were found near the quantum critical point from the usual T1/2 behavior of the conductivity characteristic of electron-electron interactions in the presence of disorder. The transport data for pressure and temperature below 1 kelvin could be collapsed onto a universal scaling curve.

Journal Article↗
PubMed1996

Molecular cloning of a glibenclamide-sensitive, voltage-gated potassium channel expressed in rabbit kidney.

Shaker genes encode voltage-gated potassium channels (Kv). We have shown previously that genes from Shaker subfamilies Kv1.1, 1.2, 1.4 are expressed in rabbit kidney. Recent functional and molecular evidence indicate that the predominant potassium conductance of the kidney medullary cell line GRB-PAP1 is composed of Shaker-like potassium channels. We now report the molecular cloning and functional expression of a new Shaker-related voltage-gated potassium channel, rabKv1.3, that is expressed in rabbit brain and kidney medulla. The protein, predicted to be 513 amino acids long, is most closely related to the Kv1.3 family although it differs significantly from other members of that family at the amino terminus. In Xenopus oocytes, rabKv1.3 cRNA expresses a voltage activated K current with kinetic characteristics similar to other members of the Kv1.3 family. However, unlike previously described Shaker channels, it is sensitive to glibenclamide and its single channel conductance saturates. This is the first report of the functional expression of a voltage-gated K channel clone expressed in kidney. We conclude that rabKv1.3 is a novel member of the Shaker superfamily that may play an important role in renal potassium transport.

Amino Acid Sequence↗
PubMed1996

Biochemical characterization of ezrin-actin interaction.

The highly related actin isoforms are thought to have different functions. We recently demonstrated a polarized distribution of actin isoforms in gastric parietal cells and association of gastric ezrin with the cytoplasmic beta-actin isoform (Yao, X., Chaponnier, C., Gabbiani, G., and Forte, J. G. (1995) Mol. Biol. Cell. 6, 541-557). Here we used ultrastructural immunocytochemistry to verify that beta-actin is located within canalicular microvilli and the apical cortex of parietal cells, similar to the localization reported for ezrin. Furthermore, we tested whether ezrin binds preferentially to cytoplasmic beta-actin compared with the skeletal muscle alpha-actin isoform. Purified cytoplasmic beta-actin (from erythrocytes) and skeletal alpha-actin were assembled with gastric ezrin. Co-sedimentation experiments showed that gastric ezrin selectively co-pelleted with the beta-actin isoform and only very poorly with alpha-actin. Binding of erythrocytic beta-actin to ezrin is saturable with a molar ratio of approximately 1:10 (ezrin:actin) and a dissociation constant approximately 4.6 x 10(-8) M. In addition, ezrin promoted pyrene-labeled actin assembly, with predominant effects on filament elongation and a distinct preference for beta-actin compared with alpha-actin. Given these isoform-selective associations, we speculate that actin isoforms might segregate into different functional domains and exert specificity by interacting with isoform-orientated binding proteins.

Actins↗
PubMed1996

Phenotyping of esterase D and acid phosphatase by rapid isoelectric focusing on PhastSystem.

A rapid isoelectric focusing method on PhastSystem was applied to investigate the distribution of esterase D (ESD) and acid phosphatase (ACP) phenotypes in 152 and 112 unrelated healthy donors, respectively, from the Han population in Beijing. Laboratory-made gels with a pH range of 5.0-7.0 and 5.0-8.0 were used for analysis of ESD and ACP, respectively, with 1 microliter sample loading. The running time was 30-40 min. Gene frequencies for ESD were 0.6809 for ESD*1 and 0.3191 for ESD*2, (sigma chi 2 = 0.8586 and P > or = 0.50); gene frequencies of ACP were 0.2009 for ACP*A, 0.7991 for ACP*B, (sigma chi 2 = 1.7892 and P > 0.20), with good agreement between the observed and the expected values.

Acid Phosphatase↗
PubMed1996

Evolutionary stability in the n-person iterated prisoner's dilemma.

The iterated prisoner's dilemma game has been used extensively in the study of the evolution of cooperative behaviours in social and biological systems. The concept of evolutionary stability provides a useful tool to analyse strategies for playing the game. Most results on evolutionary stability, however, are based on the 2-person iterated prisoner's dilemma game. This paper extends the results in the 2-person game and shows that no finite mixture of pure strategies in the n-person iterated prisoner's dilemma game can be evolutionarily stable, where n > 2. The paper also shows that evolutionary stability can be achieved if mistakes are allowed in the n-person game.

Animals↗
PubMed1996

Detection and regulation of Cu/Zn-SOD and Mn-SOD in rat cochlear tissues.

Relative levels of copper/zinc-superoxide dismutase (Cu/Zn-SOD) and manganese-superoxide dismutase (Mn-SOD) in individual cochlear tissues were detected by the use of an enzyme-linked immunosorbent assay (ELISA). A heterogeneous distribution of Cu/Zn-SOD was observed in the individual tissues of control animals: high levels were measured in the stria vascularis (SV), intermediate levels of enzyme were measured in the spiral ligament (SL), and low levels were measured in the organ of Corti region (OC); collectively, these levels were not statistically significant (P = 0.0645). Levels of Mn-SOD in individual tissues of the control group were statistically significant (P < 0.05): high levels were measured in the SV, medium levels were detected in the SL, and low levels were identified in the OC. Following the administration of methylprednisolone (MP), a significant reduction of Cu/Zn-SOD in the SV (P < 0.05) and a non-significant, but noticeable, increase (> 30%) of Mn-SOD in the OC were observed. These results indicate that levels of SOD are tissue specific and that SOD is subject to glucorticoid regulation.

Analysis of Variance↗
PubMed1996

The membrane-recruitment-and-recycling hypothesis of gastric HCl secretion.

In the unstimulated oxyntic (or parietal) cell, the primary pump for gastric HCl secretion, the H+/K+-ATPase, is retained within the cytoplasm in a membranous compartment of tubulovesicles. Neural or hormonal stimulation of acid secretion induces extensive membrane transformations consistent with a fusion and recruitment of tubulovesicles to the apical plasma membrane. The consequent placement of H+/K+-ATPase in parallel with K(+) and Cl(-) channels provides the necessary ionic flow and ATP-driven exchange for net HCl secretion. Current evidence is consistent with a recruitment and recycling of membrane transporters, such as H+/K+-ATPase, through docking/fusion machinery analogous to that in many other systems.

Journal Article↗
PubMed1996

Involvement of mouse Mlh1 in DNA mismatch repair and meiotic crossing over.

Mice that are deficient in either the Pms2 or Msh2 DNA mismatch repair genes have microsatellite instability and a predisposition to tumours. Interestingly, Pms2-deficient males display sterility associated with abnormal chromosome pairing in meiosis. Here mice deficient in another mismatch repair gene, Mlh1, possess not only microsatellite instability but are also infertile (both males and females). Mlh1-deficient spermatocytes exhibit high levels of prematurely separated chromosomes and arrest in first division meiosis. We also show that Mlh1 appears to localize to sites of crossing over on meiotic chromosomes. Together these findings suggest that Mlh1 is involved in DNA mismatch repair and meiotic crossing over.

Adaptor Proteins, Signal Transducing↗
PubMed1996

New furostanol glycosides, chinenoside IV and V, from Allium chinense.

Further studies on water-soluble components in the bulbs of Allium chinense G. Don have led to the isolation of two new furostanol saponins, chinenoside IV (1) and V (2). On the basis of chemical evidence and spectral analyses [1H-, 13C-NMR (DEPT), 1H-1H COSY (COSY45 and p-type), 1H-1H relay-COSY, 1H-13C COSY, HMBC, and FAB-MS], the structure of 1 was established as 26-O-beta-glucopyranosyl-3 beta,26-dihydroxy-23-hydroxymethyl-25(R)- 5 alpha-furost-20(22)-en-6-one 3-O-beta-xylopyranosyl(1-->4)-[alpha- arabinopyranosyl(1-->6)]-beta-glucopyranoside and that of 2 to be 26-O-beta-glucopyranosyl-3 beta, 26-dihydroxy-23-hydroxymethyl-25-(R)-5 alpha-furost-20(22)-en-6-one 3-O-alpha-arabinopyranosyl (1-->6)-beta- glucopyranoside, respectively.

Allium↗
PubMed1996

Antineoplastic agents; I. Three spirostanol glycosides from rhizomes of Dioscorea collettii var. hypoglauca.

By activity-guided fractionation, three known steroidal saponins, prosapogenin A of dioscin, dioscin and gracillin, were isolated from the total saponin fraction of Dioscorea coiletti var. hypoglauca as active compounds causing morphological abnormality of Pyricularia oryzae mycelia. The compounds also exhibited cytotoxic activity against the cancer cell line K562 in vitro. The structures of the compounds were elucidated on the basis of chemical evidence and IR, FAB-MS, 1H-NMR, 13C-NMR, and two-dimensional NMR (2D-NMR) analysis.

Antineoplastic Agents↗
PubMed1996

Inhibition of topoisomerase II by ICRF-193 prevents efficient replication of herpes simplex virus type 1.

Cellular topoisomerase II is specifically inactivated by the drug ICRF-193. This compound turns topoisomerase II into a closed clamp that is unable to cleave DNA. We have investigated the effects of this inhibitor on the replication of herpes simplex virus type 1. We show that ICRF-193 at low multiplicities of infection dramatically inhibits viral DNA synthesis and the production of infectious virus. The inhibition is less efficient at high multiplicities of infection. In addition, inhibition of viral DNA synthesis was observed only when ICRF-193 was present during the first 4 h of the infectious cycle. The transient replication of plasmids containing a herpes simplex virus type 1 origin of DNA replication, oriS, was affected by ICRF-193 in the same way. In contrast, neither cellular DNA synthesis nor replication of plasmids containing a simian virus 40 origin of DNA replication was inhibited. The observed effect on herpes simplex virus DNA replication was not caused by a decreased transcription of replication genes inasmuch as the levels of UL8, UL9, UL29, and UL30 rmRNAs were unaffected by the drug. These results suggest that topoisomerase II plays a vital role during the replication of herpes simplex virus type 1 DNA. We speculate that topoisomerase II is involved in the decatenation of newly synthesized daughter molecules.

Animals↗
PubMed1996

Stimulation of gastric acid secretion by cAMP in a novel alpha-toxin-permeabilized gland model.

It is generally believed that histamine-stimulated gastric acid secretion involves a transient elevation of intracellular Ca2+ and the adenosine 3',5'-cyclic monophosphate (cAMP)-dependent protein kinase (PKA) cascade through phosphorylation, whose actions ultimately effect the fusion of H(+)-K(+)-adenosinetriphosphatase (ATPase)-containing vesicles to the apical plasma membrane of parietal cells. To dissect the signaling events underlying gastric acid secretion, we have developed a permeabilized gastric gland model using Staphylococcus alpha-toxin. The advantage of this model is its ability to retain cytosolic components that are required for the secretory machinery. Here we show that acid secretion in alpha-toxin-permeabilized glands is a cAMP-dependent process, reaching a maximal stimulation at 100 microM cAMP. The cAMP-elicited acid secretion, as monitored by the accumulation of the weak base aminopyrine (AP), required functional mitochondria or exogenously supplied ATP. Maximal stimulation elicited by cAMP for AP uptake by permeabilized glands was 51-85% of intact glands. Moreover, secretory activity was potentiated by 0.1 mM ATP. The recruitment of H(+)-K(+)-ATPase-rich tubulovesicles into the apical plasma membrane was measured using biochemical and morphological assays, thus validating the cell activation processes in response to cAMP. From this permeabilized model, [gamma-32P]ATP was used to directly phosphorylate target proteins. A number of proteins whose phosphorylation-dephosphorylation is specifically modulated by cAMP were found. These studies establish the first permeabilized gland model in which the resting-to-secreting transition can be triggered and show that cAMP-mediated phosphorylation is correlated with secretory activity.

Aminopyrine↗
PubMed1996

Genomic structure and regulation of Kcn1, a cGMP-gated potassium channel.

We recently cloned a novel rabbit gene that encodes a 725-amino acid protein (Kcn1) (Y. Yao, A. S. Segal, P. Welling, X. Zhang, C. M. McNicholas, D. Engel, E. L. Boulpaep, and G. Desir. Proc. Natl. Acad. Sci. USA 92: 11711-11715, 1995). Kcn1 RNA injected in Xenopus oocytes leads to the expression of potassium channels that are specifically activated by guanosine 3',5'-cyclic monophosphate (cGMP). Northern blot and ribonuclease (RNase) protection analysis show that Kcn1 is differentially expressed in kidney, aorta, brain, and heart. The purpose of present study is to determine the structure of Kcn1 gene, analyze the promoter region, and identify cis-regulatory elements responsible for transcription. We find that the coding region of Kcn is intronless. The major transcription initiation site was identified by primer extension. Sequence analysis of the 5'-flanking region indicates that, although the gene lacks a typical TATA box, it does have a TATA-box-like region (-TAT-). Using luciferase reporter constructs transfected in the porcine kidney cell line (LLC-PK1), the promoter region and a 5' enhancer element were identified by deletion analysis. Phorbol esters (12-O-tetradecanoylphorbol-13-acetate) and forskolin stimulated Kcn1 gene expression 2.5- and 3.5-fold, respectively. In conclusion, we have identified the region of the novel potassium channel gene, Kcn1, that contains the promoter, a 5' enhancer, and several cis-regulatory elements and shown that gene transcription is stimulated by cAMP and phorbol esters.

Animals↗
PubMed1996

Pharmacological properties of traditional medicines. XXII. Pharmacokinetic study of mulberroside A and its metabolites in rat.

To identify the active components in Mori Cortex (Chinese medicine), Mori Cortex extracts were administered orally to rats, and then blood plasma, urine, and bile were analyzed. The results showed only a few remaining metabolites of mulberroside A. Consequently, to clarify the transitional properties of mulberroside A derivatives to tissues and the in vivo abundance ratio of mulberroside A compounds, the pharmacokinetics of mulberroside A derivatives were investigated in this study. When Mori Cortex extracts were administered orally, mulberroside A was only detected in small quantities in the plasma, and its bioavailability was about 1%. This is due to the first pass effect, by which most mulberroside A was converted into oxyresveratrol and transported into the circulating blood, and its absorption ratio was estimated at about 50%. Oxyresveratrol was found to be transported to tissues at high rates. As a result, when analyzing the pharmacological activity of the Mori Cortex in vitro, it is more useful to study oxyresveratrol than mulberroside A.

Animals↗