Biomedical subjects

Y Zou

Publications and source records attributed to Y Zou.

At least 73 records · Page 4Linked to original sources

PubMed2001

The preliminary clinical observation of array multifocal intraocular lens implantation.

PURPOSE: To evaluate the clinical effects of implantation of Array multifocal intraocular lenses. METHODS: Thirty-one cases (37 eyes) of cataract patients, including 15 males (19 eyes) and 16 females (18 eyes), were involved in this study. All patients underwent standard phacoemulsification with Array multifocal intraocular lens implantation. The complications during operation, postoperative distant visual acuity, near visual acuity, corneal curvature and visual symptoms were observed. RESULTS: The mean value of best postoperative visual acuity was recorded as follows: uncorrected distant visual acuity was 0.8, the best-corrected distant visual acuity was 0.9, uncorrected near visual acuity was 0.5, near visual acuity with distant-corrected was 0.6, the best-corrected near visual acuity was 0.9. The astigmatism of cornea was less than 1.5 D pre-operatively and post-operatively. One patient complained of glare. CONCLUSION: Array multifocal intraocular lens can provide good distant and near visual acuity. With observation of more cases and follow-up of longer time, we can draw a further conclusion.

Aged↗

PubMed2001

Comparison of trans-scleral fixation of PMMA and foldable intraocular lens in children.

PURPOSE: To observe the difference of the effects of PMMA and foldable intraocular lenses (IOLs) trans-sclerally fixed in pediatric eyes. METHODS: Thirty-two children (43 eyes) who had undergone trans-scleral fixation of IOL were retrospected, of whom 5 children were implanted PMMA IOL in both eyes, 6 children were implanted PMMA IOL in one eye and foldable IOL in the other eye, 12 children were implanted foldable IOL in one eye and 9 children were implanted PMMA IOL in one eye. Mean age was 5.3 years (range 2.5-12 years). Twelve children had traumatic cataract and the others congenital cataract before lens extraction. RESULTS: Foldable group (18 eyes): Mean follow-up was 12.1 months. Visual acuity (VA): compared with the best corrected VA before IOL fixation, postoperative best corrected VA improved in 16 eyes, remained unchanged in 2 eyes. In 14 eyes, one or two stitches were needed to seal the incision. COMPLICATIONS: Severe anterior chamber reaction was seen in 3 eyes. Intraocular bleeding was found in 3 eyes. IOL decentration was detected in 1 eye. Iris capture of IOL was seen in one eye. PMMA group (25 eyes): Mean follow-up was 20.3 months. Visual acuity (VA): compared with the best corrected VA before IOL fixation, postoperative best corrected VA improved in 19 eyes, remained unchanged in 5 eyes and got worse in one eye. In 24 eyes, one to three stitches were needed to seal the incision. COMPLICATIONS: Severe anterior chamber reaction was seen in 5 eyes. Intraocular bleeding was found in 4 eyes. IOL decentration was seen in one eye. Iris capture of IOL was seen in 3 eyes. Intraocular pressure elevated in one eye. CONCLUSION: Our study shows that trans-scleral fixation of IOL is a safe procedure in pediatric eyes. Foldable IOL showed similar effect compared with PMMA IOL in pediatric trans-scleral fixation.

Anterior Chamber↗

PubMed2001

[Hard nucleus chopping technique for non-phacoemulsification in small-incision cataract surgery: two-knife chopping].

PURPOSE: To search for a practical nuclear chopping technique for non-phacoemulsification in small-incision cataract surgery. METHODS: We designed two choppers for dividing nucleus in cataract surgery. We used them in our clinical practice of hard nuclear cataract surgery and thus improved the choppers constantly. RESULTS: Two hundred and forty-six cases (246 eyes) of cataract with their nuclei being Grade III or harder were involved in our observation. Nucleus had been divide into two halves at one chopping and the nuclear halves were delivered through a 4.5 mm incision safely in all cases. Visual acuity was 0.5 or better in 189 eyes (73.8%), 232 eyes (94.9%) and 241 eyes (97.9%) one day, seven days and three months respectively after surgery. Complications included corneal edema near the incision in 12% eyes and folding of the Descemet membrane in 25% eyes. CONCLUSION: Two-knife chopping technique has the advantages of reasonable design, small incision, little injury, no limitation by hard nucleus and easy manipulation. It is a practical and ideal chopping technique in non-phacoemulsification small-incision cataract surgery.

Aged↗

PubMed2001

[Synthesis of benzodihydropyran derivatives and evaluation of their preliminary biological activities on bone and vascular tissues].

AIM: To screen optimal drugs against postmenopausal osteoporosis with cardiovascular protective activities. METHODS: A series of benzodihydropyran derivatives were designed and synthesized in view of comprehensive observations of raloxifene and ipriflavone. The antiosteoporosis activities of compounds a-e (10(-7) mol.L-1) on the proliferation of human osteoblast cell HOS TE85 were studied. The cardiovascular protective activities were evaluated by observing their effects on proliferation of human vascular endothelium cell ECV-304 and their protective effects on ECV-304 damaged by H2O2. RESULTS: Their structures were determined by spectrums. Compounds a, b and c (10(-7) mol.L-1) were shown to significantly help proliferation of HOS TE85. In addition, b, d and e (10(-8) mol.L-1) helped proliferation of ECV-304 significantly. Compounds b and c (10(-6) mol.L-1) showed strong protective activity on ECV-304 damaged by H2O2. Compounds b and c shifted the KCl dose-response curves to the right and decreased the maximal response. CONCLUSION: Compounds b and c showed some bone and vascular protective activities which benefit postmenopausal and cardiovascular diseases.

Animals↗

PubMed2001

[Determination of warfarin in plasma by HPLC and an investigation of monitoring patients after cardiac valve replacement].

OBJECTIVE: A simple HPLC method was established for the determination of warfarin in plasma to investigate the relationship between warfarin concentration and anticoagulant effect. METHODS: The mixture of dichloromethane and hexane (1:9) was used as extracting solvent for the plasma samples. The chromatographic separation was on C18 column with a mobile phase consisting of methanol and 50 mmol/L ammonium acetate buffer (pH2.5, 70:30). RESULTS: The calibration curve was linear within 50-2000 ng/ml. The extraction recoveries of warfarin were 78.0%-81.6%. The recoveries of methodology were 103.1%-106.5%. Inter-day and intra-day RSD were 2.33%-5.46% and 5.29%-7.73%, respectively. This method was used for determining warfarin in 70 patients after cardiac valve replacement. The results showed that 44 cases had their INR within the safety range (1.31-2.35) recommended to Chinese, and of them 37(84.1%) cases had a warfarin level at 616.2 +/- 154.8 ng/ml. CONCLUSION: This method is useful in monitoring warfarin concentration during anticoagulant therapy.

Anticoagulants↗

PubMed2001

[The role of fibrinolysis in pathogenesis of middle ears adhesions].

OBJECTIVE: To investigate the role of fibrinolysis in pathogenesis of middle ears adhesions. METHODS: The amount of Tissue-type Plasminogen Activator (tPA) of 28 sections from 6 ears with adhesive otitis media (AOM) and of 22 sections from 6 normal ears was examined by Super Sensitive Biotin-Streptavidin (SSBSA) method. Amount of Fibrin of 11 sections from 3 ears with significant adhesions was compared with that of 12 sections from 3 normal ears. Qualitative analysis of light microscopy with computer-assisted image system was employed. RESULTS: In adhesive ears, tPA stains were negative in 11 of 28 sections and faint positive were 10 of 28 sections, while Fibrin stains were positive in 6 of 11 sections and strong positive were in 3 of 11 sections. In normal ears, tPA stains positive were in 8 of 22 sections and strong positive were 10 of 22 sections, meanwhile, fibrin stains were negative in 8 of 12 sections and faint positive were in 3 of 12 sections. Quantitative analysis showed that the amount of tPA was 16.70 +/- 5.11 and 39.84 +/- 6.26 in ears with AOM and normal ones respectively (P < 0.05). CONCLUSION: In adhesive ears the amount of tPA was less than that in the normal ears, whereas, the amount of Fibrin was greater in ears with AOM than that in normal ears. It indicates that fibrinolysis involved in the process of adhesion formation of AOM, which may acts as a key factor.

Fibrin↗

PubMed2001

[The mutants of calcineurin transgenic mice].

It has been reported that the constitutively active form of calcineurin transgenic mice showed significant cardiac hypertrophy and heart failure, and that the development of cardiac hypertrophy in the transgenic mice was suppressed by inhibitors for calcineurin. We recently generated the transgenic mice overexpressing the dominant negative mutants of calcineurin specifically in the heart and observed in the transgenic mice that pressure overload-induced cardiac hypertrophy was significantly attenuated as compared to wild type mice.

English Abstract↗

PubMed2000

Search for direct CP violation in nonleptonic decays of charged Xi and lambda hyperons

A search for direct CP violation in the nonleptonic decays of hyperons has been performed. In comparing the product of the decay parameters, alpha(Xi)alpha(Lambda), in terms of an asymmetry parameter, A(XiLambda), between hyperons and antihyperons in the charged Xi-->Lambdapi and Lambda-->ppi decay sequence, we found no evidence of direct CP violation. The parameter A(XiLambda) was measured to be 0.012+/-0.014.

Journal Article↗

PubMed2000

Functional analyses of three Csx/Nkx-2.5 mutations that cause human congenital heart disease.

A homeodomain-containing transcription factor Csx/Nkx-2.5 is an important regulator of cardiogenesis in mammals. Three different mutants, Gln170ter (designated A) and Thr178Met (designated B) in the helix 2 of the homeodomain and Gln198ter mutation (designated C) just after homeodomain, have been reported to cause atrial septal defect with atrial ventricular block. We here examined the functions of these three mutants of Csx/Nkx-2.5. The atrial natriuretic peptide (ANP) promoter was activated by wild type Csx/Nkx-2.5 (WT, approximately 8-fold), B ( approximately 2-fold), and C ( approximately 6-fold) but not by A. When A, B, or C was cotransfected into COS-7 cells with the same amount of WT, WT-induced activation of the ANP promoter was attenuated by A and B (A > B), whereas C further enhanced the activation. Immunocytochemical analysis using anti-Myc tag antibody indicated that transfected Myc-tagged WT, B, and C were localized in the nucleus of both COS-7 cells and cardiomyocytes of neonatal rats, whereas A was distributed diffusely in the cytoplasm and nucleus in COS-7 cells. Electrophoretic mobility shift assay showed that Csx/Nkx-2.5-binding sequences were bound strongly by WT and C, weakly by B, but not by A. Immunoprecipitation and GST pull-down assay revealed that WT and all mutants interacted with GATA-4. The synergistic activation of the ANP promoter by WT and GATA-4 was further enhanced by C but was inhibited by A and B. In the cultured cardiomyocytes, overexpression of C but not WT, A, or B, induced apoptosis. These results suggest that although the three mutants induce the same cardiac phenotype, transactivation ability and DNA binding ability are different among the three mutants and that apoptosis may be a cause for C-induced cardiac defect.

Animals↗

PubMed2000

beta-Adrenergic pathway induces apoptosis through calcineurin activation in cardiac myocytes.

Apoptosis of cardiac myocytes is one of the causes of heart failure. Here we examine the mechanism by which the activation of beta-adrenergic receptor induces cardiomyocyte apoptosis. Terminal deoxynucleotide transferase-mediated dUTP nick end labeling and DNA ladder analyses revealed that isoproterenol (Iso) induced the apoptosis of cardiac myocytes of neonatal rats through an increase in intracellular Ca(2+) levels. The Iso-induced cardiomyocyte apoptosis was strongly inhibited by the L-type Ca(2+) channel antagonist nifedipine and by the calcineurin inhibitors cyclosporin A and FK506. Iso reduced the phosphorylation levels of the proapoptotic Bcl-2 family protein Bad and induced cytochrome c release from mitochondria to the cytosol through calcineurin activation. Infusion of Iso increased calcineurin activity by approximately 3-fold in the hearts of wild-type mice but not in the hearts of transgenic mice that overexpress dominant negative mutants of calcineurin. Terminal deoxynucleotide transferase-mediated dUTP nick end labeling analysis revealed that infusion of Iso induced apoptosis of cardiac myocytes and that the number of apoptotic cardiomyocytes was significantly less in the hearts of the transgenic mice compared with the wild-type mice. These results suggest that calcineurin plays a critical role in Iso-induced apoptosis of cardiac myocytes, possibly through dephosphorylating Bad.

Animals↗

PubMed2000

Calcineurin inhibitor attenuates the development and induces the regression of cardiac hypertrophy in rats with salt-sensitive hypertension.

BACKGROUND: It remains unclear how hemodynamic overload induces cardiac hypertrophy. Recently, activation of calcium-dependent phosphatase, calcineurin, has been elucidated to induce cardiac hypertrophy. In the present study, we examined the role of calcineurin in load-induced cardiac hypertrophy by using Dahl salt-sensitive (DS) rats, which develop both pressure and volume overload when fed a high salt diet. METHODS AND RESULTS: In the DS rat heart, the activity of calcineurin was increased and cardiac hypertrophy was induced by high salt diet. Treatment of DS rats with the calcineurin inhibitor FK506 (0.1 or 0.01 mg/kg twice daily) from the age of 6 weeks to 12 weeks inhibited the activation of calcineurin in the heart in a dose-dependent manner and attenuated the development of load-induced cardiac hypertrophy and fibrosis without change of hemodynamic parameters. Additionally, treatment with 0.1 mg/kg twice daily but not with 0.01 mg/kg twice daily of FK506 from the age of 12 weeks to 16 weeks induced regression of cardiac hypertrophy in DS rats. Load-induced reprogramming of gene expression was also suppressed by the FK506 treatment. CONCLUSIONS: These results suggest that calcineurin is involved in the development of cardiac hypertrophy in rats with salt-sensitive hypertension and that inhibition of calcineurin could induce regression of cardiac hypertrophy.

Animals↗

PubMed2000

Differential incision of bulky carcinogen-DNA adducts by the UvrABC nuclease: comparison of incision rates and the interactions of Uvr subunits with lesions of different structures.

The UvrABC nuclease system from Escherichia coli removes DNA damages induced by a wide range of chemical carcinogens with variable efficiencies. The interactions with UvrABC proteins of the following three lesions site-specifically positioned in DNA, and of known conformations, were investigated: (i) adducts derived from the binding of the (-)-(7S,8R,9R,10S) enantiomer of 7,8-dihydroxy-9, 10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene [(-)-anti-BPDE] by cis-covalent addition to N(2)-2'-deoxyguanosine [(-)-cis-anti-BP-N(2)-dG], (ii) an adduct derived from the binding of the (+)-(1R,2S,3S,4R) enantiomer of 1,2-dihydroxy-3,4-epoxy-1,2,3, 4-tetrahydro-5-methylchrysene [(+)-anti-5-MeCDE] by trans addition to N(2)-2'-deoxyguanosine [(+)-trans-anti-MC-N(2)-dG], and (iii) a C8-2'-deoxyguanosine adduct (C8-AP-dG) formed by reductively activated 1-nitropyrene (1-NP). The influence of these three different adducts on UvrA binding affinities, formation of UvrB-DNA complexes by quantitative gel mobility shift analyses, and the rates of UvrABC incision were investigated. The binding affinities of UvrA varied among the three adducts. UvrA bound to the DNA adduct (+)-trans-anti-MC-N(2)-dG with the highest affinity (K(d) = 17 +/- 2 nM) and to the DNA containing C8-AP-dG with the least affinity (K(d) = 28 +/- 1 nM). The extent of complex formation with UvrB was also the lowest with the C8-AP-dG adduct. 5' Incisions occurred at the eighth phosphate from the modified guanine. The major 3' incision site corresponded to the fifth phosphodiester bond for all three adducts. However, additional 3' incisions were observed at the fourth and sixth phosphates in the case of the C8-AP-dG adduct, whereas in the case of the (-)-cis-anti-BP-N(2)-dG and (+)-trans-anti-MC-N(2)-dG lesions additional 3' cleavage occurred at the sixth and seventh phosphodiester bonds. Both the initial rate and the extent of 5' and 3' incisions revealed that C8-AP-dG was repaired less efficiently in comparison to the (-)-cis-anti-BP-N(2)-dG and (+)-trans-anti-MC-N(2)-dG containing DNA adducts. Our study showed that UvrA recognizes conformational changes induced by structurally different lesions and that in certain cases the binding affinities of UvrA and UvrB can be correlated with the incision rates. The size of the bubble formed around the damaged site with mismatched bases also appears to influence the incision rates. A particularly noteworthy finding in this study is that UvrABC repair of a substrate with no base opposite C8-AP-dG was quite inefficient as compared to the same adduct with a C opposite it. These findings are discussed in terms of the available NMR solution structures.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗

PubMed2000

Recognition and incision of site-specifically modified C8 guanine adducts formed by 2-aminofluorene, N-acetyl-2-aminofluorene and 1-nitropyrene by UvrABC nuclease.

Nucleotide excision repair plays a crucial role in removing many types of DNA adducts formed by UV light and chemical carcinogens. We have examined the interactions of Escherichia coli UvrABC nuclease proteins with three site-specific C8 guanine adducts formed by the carcinogens 2-aminofluorene (AF), N:-acetyl-2-acetylaminofluorene (AAF) and 1-nitropyrene (1-NP) in a 50mer oligonucleotide. Similar to the AF and AAF adducts, the 1-NP-induced DNA adduct contains an aminopyrene (AP) moiety covalently linked to the C8 position of guanine. The dissociation constants for UvrA binding to AF-, AAF- and AP-DNA adducts, determined by gel mobility shift assay, are 33 +/- 9, 8 +/- 2 and 23 +/- 9 nM, respectively, indicating that the AAF adduct is recognized much more efficiently than the other two. Incision by UvrABC nuclease showed that AAF-DNA was cleaved approximately 2-fold more efficiently than AF- or AP-DNA (AAF > AF approximately AP), even though AP has the largest molecular size in this group. However, an opened DNA structure of six bases around the adduct increased the incision efficiency for AF-DNA (but not for AP-DNA), making it equivalent to that for AAF-DNA. These results are consistent with a model in which DNA damage recognition by the E. coli nucleotide excision repair system consists of two sequential steps. It includes recognition of helical distortion in duplex DNA followed by recognition of the type of nucleotide chemical modification in a single-stranded region. The difference in incision efficiency between AF- and AAF-DNA adducts in normal DNA sequence, therefore, is a consequence of their difference in inducing structural distortions in DNA. The results of this study are discussed in the light of NMR solution structures of these DNA adducts.

2-Acetylaminofluorene↗

PubMed2000

Combinatorial signaling in the specification of unique cell fates.

How multifunctional signals combine to specify unique cell fates during pattern formation is not well understood. Here, we demonstrate that together with the transcription factor Lozenge, the nuclear effectors of the EGFR and Notch signaling pathways directly regulate D-Pax2 transcription in cone cells of the Drosophila eye disc. Moreover, the specificity of D-Pax2 expression can be altered upon genetic manipulation of these inputs. Thus, a relatively small number of temporally and spatially controlled signals received by a set of pluripotent cells can create the unique combinations of activated transcription factors required to regulate target genes and ultimately specify distinct cell fates within this group. We expect that similar mechanisms may specify pattern formation in vertebrate developmental systems that involve intercellular communication.

Animals↗

PubMed2000

Squeezing axons out of the gray matter: a role for slit and semaphorin proteins from midline and ventral spinal cord.

Commissural axons cross the nervous system midline and then turn to grow alongside it, neither recrossing nor projecting back into ventral regions. In Drosophila, the midline repellent Slit prevents recrossing: axons cross once because they are initially unresponsive to Slit, becoming responsive only upon crossing. We show that commissural axons in mammals similarly acquire responsiveness to a midline repellent activity upon crossing. Remarkably, they also become responsive to a repellent activity from ventral spinal cord, helping explain why they never reenter that region. Several Slit and Semaphorin proteins, expressed in midline and/or ventral tissues, mimic these repellent activities, and midline guidance defects are observed in mice lacking neuropilin-2, a Semaphorin receptor. Thus, Slit and Semaphorin repellents from midline and nonmidline tissues may help prevent crossing axons from reentering gray matter, squeezing them into surrounding fiber tracts.

Animals↗

PubMed2000

Butadiene-induced intrastrand DNA cross-links: a possible role in deletion mutagenesis.

To initiate studies designed to identify the mutagenic spectrum associated with butadiene diepoxide-induced N(2)-N(2) guanine intrastrand cross-links, site specifically adducted oligodeoxynucleotides were synthesized in which the adducted bases were centrally located within the context of the human ras 12 codon. The two stereospecifically modified DNAs and the corresponding unmodified DNA were ligated into a single-stranded M13mp7L2 vector and transfected into Escherichia coli. Both stereoisomeric forms (R, R and S,S) of the DNA cross-links resulted in very severely decreased plaque-forming ability, along with an increased mutagenic frequency for both single base substitutions and deletions compared with unadducted DNAs, with the S,S stereoisomer being the most mutagenic. Consistent with decreased plaque formation, in vitro replication of DNA templates containing the cross-links by the three major E. coli polymerases revealed replication blockage by both stereoisomeric forms of the cross-links. The same DNAs that were used for replication studies were also assembled into duplex DNAs and tested as substrates for the initiation of nucleotide excision repair by the E. coli UvrABC complex. UvrABC incised linear substrates containing these intrastrand cross-links with low efficiency, suggesting that these lesions may be inefficiently repaired by the nucleotide excision repair system.

Adenosine Triphosphatases↗

PubMed2000

Prolonged survival of heart allografts from p53-deficient mice.

BACKGROUND: Acute rejection of the heart allograft is the major cause of heart failure in the first month after transplantation. Most studies on the prevention of acute rejection have concentrated on immune suppression of the recipients, whereas little is known about the effects of genetically manipulated donor organs on heart allograft survival. Herein, we describe a mouse model of heart allografts donated by p53-/- mice that can prolong the survival time of the grafts. METHODS: Hearts of p53-/- or p53+/+ C57BL/6J mice were grafted to the neck carotid artery and jugular vein of BALB/c mice using a cuff technique. The graft survival was observed daily. The hearts were analyzed using several techniques, including histology, immunofluorescence, terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL), and Western blot analysis. RESULTS: p53+/+ allografts ceased beating at 7.6+/-0.5 days, whereas p53-/- hearts were beating at 10.5+/-1.1 days after transplantation (P<0.01). Mean histological rejection scores were significantly lower in allografts donated by p53-deficient mice. Furthermore, apoptotic cells, determined by TUNEL and a reagent kit for detection of cardiac apoptosis, were of high numbers in the allograft sections from wild-type hearts but rare in p53-/- allografts (4.2+/-1.3 vs. 0.7+/-0.5/250x field). Immunofluorescence staining and Western blot analysis revealed that high levels of p53 and proapoptotic protein Bax were expressed in wild-type grafts but not p53-/- allografts. Interestingly, Bcl-2, an antiapoptotic protein, was abundant in cardiac allografts from p53-/- mice and almost undetectable in grafts from wild-type mice. CONCLUSIONS: Thus, p53 is involved in cardiac apoptosis induced by alloimmune reaction, and prolonged survival of heart allografts can be achieved when p53 is lacking.

Animals↗

PubMed2000

Nonlinear behavior of localized space-charge waves in space-charge dominated electron beams

We present experimental observations of the abnormal growth of localized nonlinear space-charge waves in space-charge dominated electron beams passing through a resistive channel. The energy width of the space-charge waves is measured on both ends of the channel. Previous experiments had shown that, for small initial perturbations, the energy width of the slow waves increases, while the energy width of the fast waves decreases, in agreement with linear theory. We report that in the nonlinear regime (large initial perturbations), the energy width of the fast wave increases, which is unexpected, and, to the best of our knowledge, no theory exists that would predict this phenomenon.

Journal Article↗