Biomedical subjects

Y Zhong

Publications and source records attributed to Y Zhong.

At least 55 records · Page 3Linked to original sources

PubMed2000

Pharmacological comparison of P2X receptors on rat coeliac, mouse coeliac and mouse pelvic ganglion neurons.

Characteristics of P2X receptors on neurons of the rat coeliac, mouse coeliac and mouse pelvic ganglia have been studied using the whole cell voltage-clamp technique. Fast application of ATP (100 microM) on to isolated neurons voltage clamped at -70 mV induced a slowly desensitising inward current in 96% of the cells tested. Concentration-response curves for ATP yielded EC50 values of 86 microM, 64 microM and 123 microM, for rat coeliac, mouse coeliac and mouse pelvic ganglion neurons, respectively, while alpha,beta-methylene ATP was inactive. The response to ATP was antagonised by suramin, Cibacron blue and pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS). The potency of ATP was increased by extracellular acidification and by co-application of micromolar concentrations of Zn2+, while raising pH decreased it. On rat coeliac ganglion neurons, the EC50 values for ATP were 35 microM and 253 microM at pH 6.8 and 8.0, respectively. On mouse coeliac and pelvic ganglion neurons, altering the pH produced comparable changes. In conclusion, our results indicate that, in contrast to the guinea-pig coeliac ganglion, the characteristics of the P2X receptors present on rat coeliac, mouse coeliac and mouse pelvic ganglia are all identical to those present on rat pelvic ganglion, i.e. they are homomeric P2X2 receptors, or heteromultimers with P2X2 being the dominant subunit.

Adenosine Triphosphate↗

PubMed2000

Genotoxicity of two novel pesticides for the earthworm, Eisenia fetida.

In this paper, several studies were conducted to evaluate the genotoxicity of two pesticides, Imidacloprid and RH-5849, for earthworm (Eisenia fetida). Earthworms were exposed in different exposure systems to evaluate their acute toxicity and the genotoxicity of the two pesticides was evaluated by using the method of sperm deformity assessment, micronucleus test of root tip cells in Vicia faba, a mouse bone-marrow micronucleus test, and comet assay. LC(50) (interpolated concentration at which 50% mortality of test population occurs) for earthworms varied in different exposure systems. The results indicated that Imidacloprid was consistently more toxic than RH-5849 in all exposure systems. In this study, sperm deformity test was used to detect the potential adverse influences of pesticides on the reproduction of earthworms. The results demonstrated that significant induction of sperm deformity (p<0.01) and a dose-effect relationship displayed at Imidacloprid concentrations higher than 0.5 mg/kg dry soil. However, the sperm deformity frequency of groups exposed to RH-5849 did not show significant difference (p>0.05) from the control until the dose reached 100 mg/kg dry soil. The results of the V. faba micronucleus tests showed that micronuclei frequency of the exposed group did not show significant difference (p>0.05) from the control until the concentration of Imidacloprid and RH-5849 reached 100 mg/ml. The results of the mouse bone-marrow micronuclei test also indicate that two pesticides did not show significant effects (p>0.05) on the micronuclei frequency in mice bone-marrow cells until the dose reached 100 mg/kg for Imidacloprid and 300 mg/kg for RH-5849 (2/3 LD(50)). Although no genotoxicity was detected by using the micronucleus tests, the results of the comet assay showed that the two pesticides induce significant DNA damage (p<0.01) in earthworms and dose-effect relationships were displayed. The 'earthworm comet assay' is a rapid and sensitive way to screen chemicals or terrestrial environments for their DNA-damaging properties.

Journal Article↗

PubMed2000

A cost-benefit analysis of mechanical ventilation. An examination of DRG 475.

OBJECTIVE: An economic evaluation of the resources used for mechanically ventilated patients using various measures for the benefits of extending life. METHODS: Regression analysis is applied to New York State discharge data for patients under DRG 475 during 1992-96 to predict age-specific survival rates and payments per life saved. Sensitivity analysis is used to compare benefits of extending life associated with different economic values of life with the payments per life saved at each age. RESULTS: Payments per life saved decreased over time, primarily due to reduced reimbursements. Payments exceeded the age-adjusted and the quality-of-life and age-adjusted benefits for all economic values of life at ages 90 and older. CONCLUSIONS: Since the benefits of extending life associated with DRG 475 exceed the payments per life saved at most ages, economic evaluations may be best applied with psychosocial evaluations to allocate resources more ethically.

Adult↗

PubMed2000

Four new naphthylisoquinoline alkaloids from Ancistrocladus tectorius.

Four new naphthylisoquinoline alkaloids, ancistrotectoriline A (1), ancistrotectoriline B (2), 6-O-methyl-4'-O-demethylancistrocladine (3), and 6-O-methyl-4'-O-demethylhamatine (4), were isolated from the stems and leaves of Ancistrocladus tectorius, collected from Hainan Province, Southern China. Their structures were elucidated using MS and NMR methods.

Alkaloids↗

PubMed2000

Diinosine pentaphosphate: an antagonist which discriminates between recombinant P2X(3) and P2X(2/3) receptors and between two P2X receptors in rat sensory neurones.

1. We have compared the antagonist activity of trinitrophenyl-ATP (TNP-ATP) and diinosine pentaphosphate (Ip(5)I) on recombinant P2X receptors expressed in Xenopus oocytes with their actions at native P2X receptors in sensory neurones from dorsal root and nodose ganglia. 2. Slowly-desensitizing responses to alpha,beta-methylene ATP (alpha,beta-meATP) recorded from oocytes expressing P2X(2/3) receptors were inhibited by TNP-ATP at sub-micromolar concentrations. However, Ip(5)I at concentrations up to 30 microM was without effect. 3. Nodose ganglion neurones responded to alpha,beta-meATP with slowly-desensitizing inward currents. These were inhibited by TNP-ATP (IC(50), 20 nM), but not by Ip(5)I at concentrations up to 30 microM. 4. In DRG neurones that responded to ATP with a rapidly-desensitizing inward current, the response was inhibited by TNP-ATP with an IC(50) of 0.8 nM. These responses were also inhibited by Ip(5)I with an IC(50) of 0.1 microM. Both antagonists are known to inhibit homomeric P2X(3) receptors. 5. Some DRG neurones responded to alpha,beta-meATP with a biphasic inward current, consisting of transient and sustained components. While the transient current was abolished by 1 microM Ip(5)I, the sustained component remained unaffected. 6. In conclusion, Ip(5)I is a potent antagonist at homomeric P2X(3) receptors but not at heteromeric P2X(2/3) receptors, and therefore should be a useful tool for elucidating the subunit composition of native P2X receptors.

Adenosine Triphosphate↗

PubMed2000

Testing hybridization hypotheses based on incongruent gene trees.

Hybridization is an important evolutionary mechanism in plants and has been increasingly documented in animals. Difficulty in reconstruction of reticulate evolution, however, has been a long-standing problem in phylogenetics. Consequently, hybrid speciation may play a major role in causing topological incongruence between gene trees. The incongruence, in turn, offers an opportunity to detect hybrid speciation. Here we characterized certain distinctions between hybridization and other biological processes, including lineage sorting, paralogy, and lateral gene transfer, that are responsible for topological incongruence between gene trees. Consider two incongruent gene trees with three taxa, A, B, and C, where B is a sister group of A on gene tree 1 but a sister group of C on gene tree 2. With a theoretical model based on the molecular clock, we demonstrate that time of divergence of each gene between taxa A and C is nearly equal in the case of hybridization (B is a hybrid) or lateral gene transfer, but differs significantly in the case of lineage sorting or paralogy. After developing a bootstrap test to test these alternative hypotheses, we extended the model and test to account for incongruent gene trees with numerous taxa. Computer simulation studies supported the validity of the theoretical model and bootstrap test when each gene evolved at a constant rate. The computer simulation also suggested that the model remained valid as long as the rate heterogeneity was occurring proportionally in the same taxa for both genes. Although the model could not test hypotheses of hybridization versus lateral gene transfer as the cause of incongruence, these two processes may be distinguished by comparing phylogenies of multiple unlinked genes.

Biological Evolution↗

PubMed2000

ITS regions in diploids of Aegilops (Poaceae) and their phylogenetic implications.

The nucleotide sequences of the internal transcribed spacer (ITS) of nuclear ribosomal DNA in nine diploid species representing six sections of Aegilops were determined by direct sequencing of PCR-amplified DNA fragments. These sequences were aligned with two ITS sequences of additional species from Genbank. Sequence divergences were estimated using Kimura two-parameter model, and the phylogenetic analyses were performed using the maximum parsimony (MP) and the neighbor-joining (NJ) methods with PAUP and PHYLIP, respectively. The sequence divergences between the diploid species varied from 0.5% to 4.68%. The resulting MP tree and NJ tree showed relatively congruent phylogenetic relationships among these species, except Ae. caudata. Particularly, Ae. speltoides was basal within the two trees. The paraphyletic relationships between Ae. speltoides and two species of Sect. Sitopsis, and between Ae. uniaristata and two species of Sect. Comopyrum were supported strongly. The ITS data suggest that currently recognized sections within Aegilops should be reconsidered.

Base Composition↗

PubMed2000

Evolution of parental ITS regions of nuclear rDNA in allopolyploid Aegilops (Poaceae) species.

The genus Aegilops comprises approximately 25 diploid, tetraploid and hexaploid species, in which the genome types of all allopolyploids involve either U or D genome, or both of them. The internal transcribed spacer (ITS) region of 18S-26S nuclear ribosomal DNA (rDNA) from 11 allopolyploid species and 7 related diploid species in the genus were directly sequenced by pooled PCR products. Phylogenetic analyses for tracing evolutionary patterns of parental rDNA in allopolyploid species were performed using the neighbor-joining method. The D genome involved tree included three clades (CC-DDCC, DDMM-DDMMSS-DDMMUU, and MM-MhMh-DDNN), but did not include Ae. squarrosa (DD). It indicated that the rDNA of ancestral D genome had been somewhat differentiated in allopolyploids. The U genome involved tree showed that the allopolyploids and their common ancestor, Ae. umbellulata, formed a clade, suggesting that rDNA in UUMM and UUSS genomes has been homogenizing toward that of ancestral U genome. The phylogenetic pattern of U genome based on ITS sequences also supported the "pivotal-differential" hypothesis.

DNA, Plant↗

PubMed2000

Effects of photoinduced membrane rigidification on the lysosomal permeability to potassium ions.

Mechanism for the photoinduced increase in the lysosomal K+ permeability is still unknown. In this study, we investigated the effect of photodamage-induced membrane rigidification on the lysosomal K+ permeability by measuring the membrane potential with bis(3-propyl-5-oxoisoxazol-4-yl)pentamethine oxonol and by monitoring proton leakage with p-nitrophenol. Membrane fluidity was measured by the steady-state fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene. Methylene blue-mediated photodamage to lysosomes decreased their membrane fluidity and increased their K+ permeability. The photoinduced increase in the K+ permeability can be reversed by fluidizing the rigidified lysosomal membranes with benzyl alcohol. The results suggest that the membrane rigidification induced by photodamage may increase lysosomal K+ permeability. This conclusion is supported by the observation that rigidifying lysosomal membranes by the treatment with membrane rigidifier cholesteryl hemisuccinate also enhanced the lysosomal K+ permeability.

Animals↗

PubMed2000

[Cloning and sequence analysis of human genomic DNA of augmenter of liver regeneration hepatitis].

OBJECTIVE: To clone the human genomic DNA of augmenter of liver regeneration (ALR) and specify the intron-exon structure. METHODS: Using human ALR cDNA sequence as a reference and BLAST path as a nucleotide homology search tool, GenBank has been searched for ALR homologous genomic DNA sequence. The intron-exon sequences were defined by the Breathnath-Chambon rule. RESULTS: The coding sequence of human ALR consists of 3 exons, and is similar to murine ALR genomic DNA structure. The human ALR genomic DNA is 1813 nt long and codes a protein of 125 amino acid residues. CONCLUSION: Human genomic DNA of ALR consists of 3 exons and 2 introns.

Base Sequence↗

PubMed2000

Expression of human single-chain variable fragment antibody against non-structural protein 3 of hepatitis C virus antigen in e.coli.

OBJECTIVE: To express human single-chain variable fragment (ScFv) antibody against non-structural protein 3 (NS(3)) of hepatitis C virus in E.coli. METHODS: The recombinant phages were panned by NS(3) antigen which was coated in a microtiter plate. After five rounds of biopanning, 66 clones were identified specific to NS(3) antigen. E.coli host XL(1)-Blue was transformed and induced by IPTG. The specificity of ScFv was evaluated by ELISA and dot blot hybridization. RESULTS: ScFv-NS(3) DNA digestion and sequencing data showed that the ScFv gene was composed of 750bp. ELISA and dot blot hybridization demonstrated that the soluble human single-chain Fv antibody to hepatitis C virus NS(3) antigen could combine different origins of NS(3) antigen. CONCLUSION: NS(3)-ScFv antibody expressed by E.coli host XL(1)-Blue has the activity and specificity to combine different origins of HCV NS(3) antigen.

Escherichia coli↗

PubMed2000

[Recognition of multiple information of human auricular points by linear model].

The three variables of the electric characteristic of human auricular points can be regarded as observed targets that reflect the physiologic or pathologic changes. Medical principle design follows the theory of the channels and collaterals and the viscera-state doctrine of traditional Chinese medicine and that of the pattern recognition. The linear integration model can be established by drawing the characteristic variables of the correlation groups of the auricular points and applying the multi-variable normalization. With this model, the recognition of the three variations of the auricular points can be of use for differential diagnosis. In this paper, the test to identify the cases of Upper-Digestive tract achieves good result. This research, based on the integration of modern science with traditional Chinese medicine, provides a method for building the specialist system of the auricular point diagnosis, and probably has some prospect in clinical application.

Acupuncture Points↗

PubMed2000

Gender difference in letrozole pharmacokinetics in rats.

AIM: To study gender difference in letrozole (Letr) pharmacokinetics in rats. METHODS: Letr concentrations in plasma and tissues were determined after ig administration of Letr 2 mg/kg. Recoveries of Letr in urine and feces were also analyzed. RESULTS: Marked gender differences were found 6 h after ig Letr 2 mg/kg, the plasma concentrations of Letr in male rats were significantly (P < 0.01) lower than those in female rats. For example, at 24, 36, 48, and 72 h after administration, plasma concentrations in female rats were about 3.3, 5.6, 10.5, and 7.4-fold of that of male rats, respectively. AUC value of Letr in male was only about one-third of that in female rats. Estimated terminal phase half-lives (T1/2) were 10.5 and 40.4 h, respectively. In female rats, cumulative excreted fractions of Letr in urine and feces were 5.8% +/- 1.4% and 6.6% +/- 1.1% within 120 h after administration, respectively, but in male rats, the excreted fractions of Letr in urine and feces were only 1.30% +/- 0.59% and 0.87% +/- 0.31%. Letr concentrations in female rat tissues were significantly (P < 0.01) higher than those in male rat tissues 24 h after administration. CONCLUSION: There are marked gender differences in Letr pharmacokinetics in rats.

Animals↗

PubMed2000

[Preparation of galactosyl-insulin with double saccharide density and a study of its hepatic targeting property].

This study was intended to improve the technical procedure so as to increase the saccharide density of galactosyl-recombinant insulin and elevate its liver targeting property. Using a branched compound 3,5-dihydroxy benzoic acid as the base of a conjugating bridge, the authors prepared a new double galactosyl-recombinant insulin, whose saccharide density being two times as high as that of galactosyl-recombinant insulin. The double gal-insulin conjugate, gal-insulin conjugate and original insulin were labeled with 131I, and then the three kinds of 131I labeled compounds were tested in rabbit whole body imaging to measure their properties of liver targeting. The peak values of rabbit liver concentration for double gal-insulin, gal-insulin and original insulin were 59.5%, 43.8% and 21.5%, respectively. These results demonstrate that for elevating the liver targeting property of galactosyl-recombinant compounds, a branched agent like 3,5-dihydroxyl benzoic acid can be adopted as an effective medium.

Animals↗

PubMed2000

[Purification and properties of degrading enzyme of organophosphorus pesticides from Aspergillus ornatus Z58].

Degrading enzyme of organophosophorus pesticides was purified from Aspergillus oryzeZ58 by (NH4)2SO4 precipitation, Sephadex G-100 gel filtration, DEAE-cellulose chromatography with 34.2-fold purification, 17.8% recovery and 76.2 U/mg specific activity. The purified enzyme was homogeneous on polyacrylamide gel electrophoresis. The molecular weight of the enzyme estimated with Sephadex G-100 was 67000. The optimal conditions for activity were pH 7.2, temperature 45 degrees C. The enzyme was stable over the range of pH 6-10 and below 40 degrees C, the activity was inhibited by SDS and stimulated by Cu2+, the substrate ranges were nonspecific to organophosophorus pesticides.

Aspergillus↗

PubMed2000

Measurement of episcleral venous pressure in normal Chinese people.

PURPOSE: To measure episcleral venous pressure (EVP) in normal Chinese people. METHODS: EVP was measured in 110 eyes of 74 subjects distributed in seven age groups from 10 to 80 years using episcleral venomanometer (EV-310). The differences in EVP values were analyzed with age and either eye. RESULTS: EVP values of the 110 eyes appeared as normal distribution. The value mean +/- SD was (9.11 +/- 1.22) mmHg, and the 95% normal value range was 6.73 mmHg -11.50 mmHg. No statistically significant difference of EVP was found in the seven age groups. And there was no statistically significant difference of EVP between the right and left eyes. CONCLUSIONS: The value mean +/- SD of EVP in Chinese normal eyes in 9.11 mmHg +/- 1.22 mmHg. The normal value of EVP does not vary with age and either eye.

Adolescent↗

PubMed2000

The changes of TGF-alpha, TGF-beta 1 and basic FGF messenger RNA expression in rabbit cornea after photorefractive keratectomy.

OBJECTIVE: To study the mechanism of haze formation and investigate the expression changes of transforming growth factor-alpha (TGF-alpha), transforming growth factor-beta 1(TGF-beta 1) and basic fibroblast growth factor (bFGF) mRNA in corneal epithelium and stroma after photorefractive keratectomy (PRK). METHODS: Sixteen white rabbits were randomly divided into 4 groups, and PRK was performed on each eye of 12 rabbits. The haze formation was examined under a slit-lamp microscope at the 1st, 2nd and 3rd month after PRK, and the expressions of TGF-alpha, TGF-beta 1 and bFGF mRNA were detected with in situ hybridization. RESULTS: The corneal haze formed at the 1st month after PRK. The most prominent haze formation was observed at the 2nd month, and declined gradually at the 3rd month after ablation. TGF-alpha mRNA expression was presented on the normal corneal epithelium and not on the corneal stroma. TGF-beta 1 and bGFG mRNA were expressed by both corneal epithelium and stroma. The capacities for cornea tissue expression of three growth factors mRNA increased after PRK, and the peaks appeared on the 1st, 2nd month. The extent for expressions of three growth factors related proportionally to the haze formation. CONCLUSION: Three growth factors took part in promoting corneal wound healing after PRK, and might contribute to corneal haze formation and development.

Animals↗

PubMed2000

[Effect of amniotic membrane on expressions of TGF-beta 1, collagens I, III and fibronectin in rabbit corneal healing after photorefractive keratectomy].

OBJECTIVE: To observed the effect of amniotic membrane transplantation (AMT) on expressions of transforming growth factor-beta 1(TGF-beta 1), collagens I, III and fibronectin (FN) in rabbit corneal healing after photorefractive keratectomy (PRK), and investigate the anti-scarring formation mechanism of AMT. METHODS: Ten rabbits underwent bilateral PRK to correct 8 diopters of myopia. One eye was randomly transplanted with preserved human amniotic membrane, and the other eye served as the control. The expressions of TGF-beta 1, collagens I, III and FN were studied by immunohistochemistry at 4 weeks after operation. RESULTS: The expression of TGF-beta 1 in corneal epithelium and keratocytes and collegans in anterior stroma was significantly less in AMT group than in the control group. The expressions of collagens III and FN in anterior stroma of ablation area were also significantly less in AMT group than in the control group. The staining of collagen I had no significant difference between the AMT group and the control group. CONCLUSION: The expressions of TGF-beta 1, collagens III and FN can be suppressed by amniotic membrane after PRK. These data suggest that part of the anti-scarring effect of AMT may be mediated through the suppression of TGF-beta 1, collagens III and FN expression.

Amnion↗