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Biomedical subjects

Z Y Zhou

Publications and source records attributed to Z Y Zhou.

At least 19 recordsLinked to original sources
PubMed2001

Photoluminescent metal-sulfur clusters derived from tetrathiometalates: metal-to-metal charge-transfer excited states of d0-d10 heterobimetallic sulfido clusters with bulky phosphine ligands.

Reactions of MS4(2-) (M = Mo, W) with M'(PCy3)X (M'=Ag/Au, X= ClO4/Cl) and [Cu2(dcpm)2(MeCN)2](ClO4)2 (dcpm = bis(dicyclohexylphosphino)methane) afforded heterometallic sulfido clusters [M'2(PCy3)2(MS4)] (M=Mo, M'=Au: 2; M=W, M'=Ag: 3, Au: 4) and [Cu4(dcpm)4(MS4)](ClO4)2 (M=Mo: 5 x (ClO4)2, W: 6 x (ClO4)2), all of which, except 4, have been characterized by X-ray structure determination. Clusters 5 x(ClO4)2 and 6 x (ClO4)2 feature unusual 16-membered [Cu4P5C4] metallamacrocycles formed on the respective tetrathiometalate anion templates and have unusually long Cu-S bonds and Cu...M distances for metal sulfur clusters that contain a saddle-shaped [Cu4MS4] core. Low-energy absorption bands are observed in their electronic spectra at approximately 562 and 467 nm, respectively, assignable to MMCT transitions; quasireversible reduction waves are observed with E(1/2) = -1.43 (52+) and -1.78 V (62+) versus FeCp2(0/+); and they are emissive either in the solid state or in solution. The emission of 6(2+) can be quenched by both electron acceptors, such as methylviologen, or electron donors, such as aromatic amines, with the excited state reduction potential E(62+*/6+) estimated to be approximately 1.13V versus a normal hydrogen electrode.

Journal Article↗
PubMed2001

Interaction between dioxoruthenium(VI) porphyrins and hydroxylamines: coordination of N-substituted hydroxylamine to ruthenium and X-ray crystal structures of ruthenium complexes with a unidentate nitrosoarene ligand.

The interactions between dioxoruthenium(VI) porphyrins 1 with N-phenylhydroxylamine or unsubstituted hydroxylamine are described. Reaction of complexes 1 with excess PhNHOH leads to isolation of bis(nitrosobenzene)ruthenium(II) porphyrins 3 and mono(nitrosobenzene)ruthenium(II) porphyrins 4. Both the types of ruthenium complexes are characterized by 1H NMR, IR, and UV/Vis spectroscopy, and mass spectrometry. The X-ray structure determinations on [Ru(II)(TPP)(PhNO)2] (3a), [Ru(II)(2,6-Cl-TPP)(PhNO)2] (3e), and [Ru(II)(4-MeO-TPP)(PhNO)(PhNH2)] (4d) (TPP tetraarylporphyrin) disclose a unidentate nitrosoarene coordination in all these complexes, with Ru-N(PhNO) bond lengths of 2.003(3) (3a, average), 1.991(3) (3e, average), and 2.042(2) A (4d). In the case of 4d, the Ru-N(PhNH2) bond length is found to be 2.075(3) A. Mechanistic investigations reveal the formation of intermediates [Ru(II)(Por)(PhNO)(PhNHOH)] (5; Por=porphyrin), a ruthenium complex with N-substituted hydroxylamine ligand, in the "1 + PhNHOH" system. The Ru-NH(OH)Ph moiety in 5 undergoes no rapid exchange with free PhNHOH in solution at room temperature, as revealed by 1H NMR spectroscopy. Unlike the interaction between complexes 1 and PhNHOH, reaction of such complexes with NH2OH affords nitrosylruthenium(II) porphyrins [Ru(II)(Por)(NO)(OH)] (6).

Catalysis↗
PubMed2001

Biosynthetic studies on the cyclopentane ring formation of allosamizoline, an aminocyclitol component of the chitinase inhibitor allosamidin.

Allosamizoline (1) is an aminocyclitol component of allosamidin, a Streptomyces metabolite, and has a cyclopentane ring originated from D-glucosamine. Biosynthesis of the cyclopentane ring was studied by feeding experiments with a variety of deuterium-labeled glucosamine and glucose. In the feeding experiments with [3-(2)H]- and [4-(2)H]-D-glucosamine and [1-(2)H]-D-glucose, deuterium was incorporated into C-3, C-4, and C-1 of 1, respectively. On the other hand, feeding experiments with [5-(2)H]- and [6,6-(2)H(2)]-D-glucosamine showed that deuterium on C-5 and one of the two deuterium atoms on C-6 of glucosamine were lost during the cyclopentane ring formation of 1. In the feeding experiments with (6R)- and (6S)-[6-(2)H(1)]-D-glucose, the (6R)-deuterium of glucose was incorporated into the proS position on C-6 of 1, but the (6S)-deuterium of glucose was not incorporated into 1. These results suggested that an intermediate with a 6-aldehyde group is involved in the biosynthesis of the cyclopentane ring moiety of 1 and overall inversion of stereochemistry of the C-6 methylene group occurred by stereospecific oxidation and reduction on C-6 during the formation of 1. The 6-aldehyde intermediate may play a key role in the biosynthetic step(s) of cyclization to form the cyclopentane ring and/or deoxygenation at C-5.

Acetylglucosamine↗
PubMed2001

Asymmetric inter- and intramolecular cyclopropanation of alkenes catalyzed by chiral ruthenium porphyrins. Synthesis and crystal structure of a chiral metalloporphyrin carbene complex.

Extensive investigations of asymmetric intermolecular cyclopropanation of terminal alkenes with diazoacetates catalyzed by ruthenium porphyrin [Ru(P*)(CO)(EtOH)] (1, H2P = 5,10,15,20-tetrakis[(1S,4R,5R,8S)-1,2,3,4,5,6,7,8-octahydro-1,4:5,8-dimethanoanthracene-9-yl]porphyrin) and the application of catalyst 1 to asymmetric intramolecular cyclopropanation of allylic or homoallylic diazoacetates are described. The intermolecular cyclopropanation of styrene and its derivatives with ethyl diazoacetate afforded the corresponding cyclopropyl esters in up to 98% ee with high trans/cis ratios of up to 36 and extremely high catalyst turnovers of up to 1.1 x 10(4). Examination of the effects of temperature, diazoacetate, solvent, and substituent in the intermolecular cyclopropanation reveals that (i) both enantioselectivity and trans selectivity increase with decreasing temperature, (ii) sterically encumbered diazoacetates N2CHCO2R, such as R = Bu(t), and donor solvents, such as diethyl ether and tetrahydrofuran, are beneficial to the trans selectivity, and (iii) electron-donating para substituents on styrene accelerate the cyclopropanations, with the log(k(X)/k(H)) vs sigma(+) plot for para-substituted styrenes p-X-C6H4CH=CH2 (X = MeO, Me, Cl, CF3) exhibiting good linearity with a small negative rho(+) value of -0.44 +/- 0.09. In the case of intramolecular cyclopropanation, complex 1 promoted the decomposition of a series of allylic diazoacetates to form the cyclopropyl lactones in up to 85% ee, contributing the first efficient metalloporphyrin catalyst for an asymmetric intramolecular cyclopropanation. Both the inter- and intramolecular cyclopropanations were proposed to proceed via a reactive chiral ruthenium carbene intermediate. The enantioselectivities in these processes were rationalized on the basis of the X-ray crystal structures of closely related stable chiral carbene complexes [Ru(P*)(CPh2)] (2) and [Ru(P*)(C(Ph)CO2CH2CH=CH2)] (3) obtained from reactions of complex 1 with N2CPh2 and N2C(Ph)CO2CH2CH=CH2, respectively.

Journal Article↗
PubMed2001

Reactive oxygen species uncouple external horizontal cells in the carp retina and glutathione couples them again.

We have investigated the effect of free radicals on the electrical gap junctions between horizontal cells in the carp retina. In our previous study, L-buthionine sulfoximine, an inhibitor of glutathione synthesis, caused uncoupling of horizontal cells four days after injection. In the present study, we have used paraquat, a generator of exogenous reactive oxygen species, to investigate whether it was the depletion of glutathione or an increase in the level of reactive oxygen species which resulted in horizontal cell uncoupling after L-buthionine sulfoximine injection. Intracellular recordings were made from L-type horizontal cells at various time-points after intravitreal injection of paraquat. Injection of 25nmol paraquat caused an increase in response amplitude to central spot light stimuli by two days after injection, which continued for a further two to three days and had almost disappeared by seven days after injection. There was also a sharp increase in reactive oxygen species production, peaking at four days and disappearing by seven days after injection, and an accompanying depletion and a restoration of glutathione levels with a similar time-course. Marking cells with Lucifer Yellow clearly illustrated uncoupling of horizontal cells after paraquat injection. If paraquat and L-buthionine sulfoximine were injected simultaneously, the increase in response to central spots was observed as early as one day after injection. This response amplitude was not more enhanced than that observed after L-buthionine sulfoximine injection alone, although a dramatic increase in the level of reactive oxygen species was observed. From these results, we suggest that reactive oxygen species are involved in uncoupling, while recovery from uncoupling is dependent on glutathione. Furthermore, we conclude that a balance between glutathione and reactive oxygen species levels is the most important factor controlling gap junctional intercellular communication of L-type horizontal cells in the carp retina.

Animals↗
PubMed2001

[The cloning of apple ferritin gene (Apfl) from Malus xiaojinensis Cheng et Jiang and its structure analysis].

The special primers were designed based on the sequence information of plant ferritin genes reported in the literature and used for polymerase chain reaction (PCR) with the genomic DNA of Malus xiaojinensis Cheng et Jiang in an attempt to clone apple ferritin gene. A single fragment of 771 bp was successfully obtained from the PCRs and cloned in this study. The sequence and homology analysis results of the fragment showed that the deduced amino acids of the fragment had a ninety-nine percent homology to that of the soybean ferritin gene reported by Lescure et al. (1991). A comparison in details of the nucleotide sequence of the clone and that of the soybean ferritin gene showed that they consisted of the same open reading frame (ORF, 753 bp) and that the cloned fragment had complete initial and stop codes. Within the ORF no introns were found and there were no nucleotide difference in the transit peptide region (TP) of the gene, but five nucleotide mutations were found in the mature peptide region (MP), among which four were synonymous mutations.

Amino Acid Sequence↗
PubMed2001

Simultaneous nitrogen and phosphorus removal under low dissolved oxygen conditions.

A full-scale test was operated by using low dissolved oxygen activated sludge process to enhance biological nitrogen and phosphorus removal. When the influent concentrations of CODcr, TN and TP varied in a range of 352.9 mg/L-1338.2 mg/L, 34.4 mg/L-96.3 mg/L, and 2.21 mg/L-24.0 mg/L, the average removal efficiencies were 94.9%, 86.7% and 93.0%, respectively. During the test period of two months, effluent means of CODcr, BOD5, NH3-N, TN and TP were below 50 mg/L, 25 mg/L, 10 mg/L and 1.0 mg/L, respectively. The low dissolved oxygen activated sludge process has a simple flow sheet, fewer facilities and high N and P removal efficiency. It is very convenient to retrofit the conventional activated sludge process with the above process.

Bioreactors↗
PubMed2000

Synthesis of a new chiral ligand, 6, 6'-dihydroxy-5, 5'-biquinoline (BIQOL) and its applications in the asymmetric addition of diethylzinc to aldehydes.

A new chiral ligand 6, 6'-dihydroxy-5, 5'-biquinoline (BIQOL, 2) was prepared via Cu2+ mediated coupling. The resolution was carried out by separating the corresponding ditrifluomethanesulfonate on chiral column. When applied to the enantioselective addition of diethylzinc to aromatic aldehydes, this ligand induced the reaction with enantioselectivity equivalent to that induced by BINOL. The effects of solvent and reaction temperature on enantioselectivity were also studied.

Journal Article↗
PubMed2000

Prevalence of antibodies to Toxoplasma gondii in the sera of rare wildlife in the Shanghai Zoological Garden, People's Republic of China.

The prevalence of antibodies to Toxoplasma gondii in the sera of rare wildlife in the Shanghai Zoological Garden, PR China, was examined using a modified agglutination test (MAT) and an enzyme-linked immunosorbent assay (ELISA). Forty-one (35%) of 117 animals belonging to two classes, 10 orders, 18 families, 37 genera and 52 species (including sub-species) were sero-positive for MAT. By MAT, T. gondii antibodies were found in 11.1% (4/36) of birds, in 25% (4/16) of primates, in 69.4% (25/36) of carnivores and in 27.6% (8/29) of herbivores. Thirty-three (33.7%) of 98 animals tested by protein A ELISA were sero-positive. By ELISA, T. gondii antibodies were found in none of 36 birds, in 33.3% (4/12) of primates, in 87.1% (27/31) of carnivores and in 10.5% (2/19) of herbivores.

Agglutination Tests↗
PubMed2000

[Construction of silkworm RAPD molecular linkage map].

In this research, a RAPD linkage map of Bombyx mori was constructed with Dazao/C108 and their F2 generation. The map consists of 182 RAPD loci, of which 103 loci come from Dazao and from the first 23 linkage groups and the other 79 loci come from C108 and form the second 16 linkage groups. This map covered a total genetic distance of over 1,148.3 cM (centimorgan). It could be integrated with the SADF map of the same materials constructed in our laboratory and the corresponding RFLP linkage map.

Animals↗
PubMed2000

[Expression of single-chain Fv antibody for anti-beet necrotic yellow vein virus in Escherichia coli].

The heavy chains variable region gene (VH) of monoclonal antibody against beet necrotic yellow vein virus (BNYVV) was amplified from total DNA extracted from anti-BNYVV hybridoma cells by PCR. Sequencing showed that the VH belongs to mouse subgroup II(A) and contains 360 bp, which code one hundred and twenty amino acids. The VH and VL genes were inserted into a plasmid which contains a linker sequence for constructing scFv gene. The new vector named pTC scFv. The scFv was produced in Escherichia coli and appeared binding activity with BNYVV antigen by ELISA method.

Amino Acid Sequence↗
PubMed1999

Glutathione depletion causes an uncoupling effect on retinal horizontal cells through oxidative stress.

To investigate a physiological role of glutathione in the horizontal cells of carp retina, the gap junctional intercellular communication between horizontal cells was studied using the techniques of intracellular recording of light-induced responses and coupling of the fluorescence dye Lucifer Yellow. Intravitreal injection of 2.5 micromol L-buthionine sulfoximine, an inhibitor of glutathione synthesis, induced a dramatic reduction (20% of control) of retinal glutathione level two days after treatment. The low level of glutathione continued for a further four to five days, and thereafter gradually recovered to about 40% (20 days after injection) and 70% (50 days after injection) of the control level. The spatial properties of the photopic L-type horizontal cell response were examined by enlarging the diameter of the central spot and peripheral annulus over the recording point. In normal retinas, the response amplitude of horizontal cells was monotonically enhanced as the diameter of the spot increased (0.5-4.0 mm) and correspondingly the dye diffusion area was wide, as the injected Lucifer Yellow normally diffused to several neighboring cells. Treatment with L-buthionine sulfoximine significantly altered the spatial properties of horizontal cells by increasing the response amplitude to central spots and slightly decreasing that to peripheral annuli, which were observed by four days after injection. It also restricted intracellular Lucifer Yellow to one or two cells. Accompanying the recovery of the cellular level of glutathione, the spatial properties and dye coupling of horizontal cells were restored to normal. A time lag (two days) of initiation in retinal glutathione depletion and alteration of spatial or dye coupling properties of horizontal cells is discussed, together with reactive oxygen species accumulation.

Animals↗
PubMed1998

Proliferative activity of calcifying odontogenic cysts as evaluated by proliferating cell nuclear antigen labeling index.

The calcifying odontogenic cyst (COC) presents with diverse histological features; thus, several subclassifications have been proposed. To evaluate the significance of the various histological features and subtypes of COC from the perspective of proliferative activity, the proliferating cell nuclear antigen (PCNA) labeling index (LI; the percentage of positive nuclei) was assessed immunohistochemically in 25 cases of COC (21 benign and four malignant). All of the benign cases were of the cystic variety and further subclassified into non-proliferative subtype (NPS; four cases); proliferative subtype (PS; eight cases); and COC associated with odontoma (COCaO, nine cases). The PCNA LI of the malignant COC (65.2+/-5.6) was significantly higher than that of the benign COC (11.6+/-9.0; P = 0.002). Non-proliferative subtype (6.8+/-2.8) showed the lowest PCNA LI and PS (17.2+/-11.2) the highest of among the three subtypes of benign cystic COC (P = 0.028). In nine cases of COCaO, six showed epithelial lining of the non-proliferative type as NPS and the other three had lining with proliferative features as PS. The PCNA LI of the latter COCaO group (14.3+/-6.6) was significantly higher than that of the former (6.1+/-4.3; P = 0.05), as seen between PS and NPS. These results demonstrate that PCNA LI is a possible parameter for differentiating malignant COC from benign COC and, whatever the subtypes, the proliferative features in the lining are the main factor influencing the proliferating activity of COC.

Cell Division↗
PubMed1997

A new model for heterotopic aortic valve transplantation.

A new model for heterotopic aortic valve transplantation in the rat is described. A composite allograft with an intact aortic valve and partial mitral valve was harvested from 4-month-old (400-450 g) Long-Evans rats and grafted heterotopically into the abdominal aorta of 4-week-old (80-100 g) rats with an optimal size match. At the end of a 1-month observation period, all experimental animals were alive and all showed 100% patency of the aortic valve allografts on microscopic evaluation after death (n=40). Unlike previously used methods, the proposed model allows for the preservation of all three aortic valve cusps and a more remote placement of the anastomotic suture line from the aortic valve annulus. The use of younger recipient rats improves size match and amplifies allograft calcification. The purpose of this study was to provide an animal model to evaluate modalities of preservation and chemical treatment for aortic valves used as allografts or bioprosthesis.

Animals↗
PubMed1997

Development and application of ultrasonic surgical instruments.

In this paper, a new approach for designing ultrasonic surgical instruments (USI) is presented. These medical instruments convert an ultrasonic signal into a mechanical vibration by utilizing a magnetostrictive method and have been found to be very useful for various medical procedures. The implemented system consists of an ultrasonic generator, a transducer, and waveguide instruments. The generator produces a high-current ultrasonic signal. The transducer converts this signal into a mechanical vibration. By use of the waveguide instrument, the vibration can be propagated and amplified. This new type of USI possesses a comprehensive ability to stop bleeding, cut bone tissues, regulate frequency automatically, control temperature, etc. The results from animal experiments and from human clinical operations show that the developed USI has the advantages in various aspects over the conventional equipment.

Abdominal Muscles↗
PubMed1996

Effects of Coriolus versicolor polysaccharides on superoxide dismutase activities in mice.

AIM: To study if Coriolus versicolor polysaccharides (CVP) influence the superoxide dismutase (SOD) activities in mice. METHODS: Normal, tumor-bearing, and radiated ICR mice were injected ip with CVP daily for 3-15 d. The SOD activity was assayed by epinephrine autoxidation test. RESULTS: The SOD activities in lymphocytes and thymus were increased by CVP in both the normal mice with or without delayed hypersensitivity (DH). In tumor-bearing mice, CVP exerted not only inhibitory effects on tumor, growth and SOD activity in tumor tissue but also complete or partial restorative effects on the suppressed DH and on the declined SOD activities in lymphocytes, spleen, and thymus. The total SOD and manganese-containing SOD (MnSOD) activities in lymphocytes and thymus were dose-dependently enhanced by CVP (5-20 mg.kg-1) on d 3 after the tumor transplantation. In the mice exposed to 60Co (3 or 6 Gy), DH and SOD activities were dose-dependently decreased. These changes were completely or partly prevented by CVP. CONCLUSION: CVP exerted the favorable effects on SOD activities in mice. Coriolus versicolor polysaccharides (CVP) exert inhibitory effects on experimental and clinical tumors. These effects are presumed to be mediated mainly by host-defence mechanism, especially immunological responeses. Superoxide dismutase (SOD) plays an important role in protecting cells against superoxide radical (O2-.) damages and over-production of O2-. or SOD abnormities exist in many diseases. The present study was to investigate if the CVP could exert some favorable effects on SOD activities in vivo.

Animals↗
PubMed1995

The effects of alloplastic implant onlays on bone in the rabbit mandible.

The relative importance of the factors that contribute to the bone erosion seen underlying alloplastic implants remains unknown. This study was designed to examine the effects of different alloplastic onlays on the mandible in a rabbit animal model. Three alloplastic materials (soft solid silicone, methyl methacrylate, and porous polyethylene) were examined to determine the importance of implant composition in bone resorption. Thin (1.5-mm) and thick (6-mm) onlays were used to determine the relative importance of implant thickness. Fluorescent markers were administered at different time intervals to evaluate the patterns of new bone formation. A total of 96 implants placed on the mandibles of 16 animals were examined grossly, histologically, and under fluorescent microscopy after 12 and 24 weeks. The frequency and degree of bone erosion were related both to the type of alloplast and to the thickness of the implant. Silicone implants were associated with the greatest amount of bone resorption (p < 0.01). Thicker silicone implants were associated with a greater degree of thinning (p < 0.05). Bone resorption beneath the implants was documented by the presence of osteoclasts actively eroding bone and by changes in the normal patterns of the fluorescent markers. Both the thin methyl methacrylate and the thin porous polyethylene implants had a low incidence of bone thinning. The thick methyl methacrylate implants caused more erosion than the thin implants of the same material, although this was less than the silicone groups. Increasing the thickness of porous polyethylene implants did not adversely affect the underlying bone.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗