Biomedical subjects

N Zhu

Publications and source records attributed to N Zhu.

At least 37 records · Page 2Linked to original sources

PubMed2001

[Microbial degradation of polychlorinated dibenzo-p-dioxins].

PCDDs-degrading bacterial strains were isolated from soil and oxic-sediments polluted by PCDDs. One of them was identified as Pseudomonas sp. EE41. They are capable of growing on and degrade mono- and di-chlorinated dibenzo-p-dioxins as a sole carbon source. The biodegradability of TrCDD and TCDD can be enhanced through primary nutrient of co-metabolism of o-CDB, thus, 1,2,3-TrCDD and 2,3,7,8-TCDD were degraded by 33% (at the concentration of 1.2 mg/L, within 3 weeks) and 37.8% (at the concentration of 0.1 mg/L, within 3 weeks) respectively. Most highly chlorinated dibenzo-p-dioxins (P-CDD, H6-, H7-CDD and OCDD) tested in this study were accumulated in bacterial cells, but could not be degraded.

Biodegradation, Environmental↗

PubMed2001

A histomorphometric and molecular study on stress adaptability of freeze-dried bone allograft.

OBJECTIVE: To Investigate stress adaptability of freeze-dried bone allograft. METHODS: Cortical and cancellous allograft were transplanted to each side of the midshaft diaphyseal ulna in two groups of 28 animals. The left transplanted allograft was free from fixation and bore a normal physiological load, while the right transplanted allograft was protected from loading by a simple external fixator and bore less load. Animals were sacrificed at the 2nd, 4th, 8th, 16th week after transplantation and specimens were taken out for bone histomorphometry studies and analysis of collagen gene expression by in situ cDNA-mRNA hybridization. RESULTS: Labeled surface(LS) and bone mineral apposition rate(MAR) of the normally loaded graft-host bone interface were significantly higher than that of the less loaded side at the 4th, 8th, 16th week after transplantation. Parameters reflecting the internal repair process of the allograft, such as LS in cortical and cancellous bone or MAR in cortical bone of the normally loaded side were significantly higher than those of the less loaded side at the 16th week after transplantation. The result of in situ hybridization indicated that more osteoblast-like cells expressing the type I collagen gene were found in the interface or interior of normally loaded grafts. CONCLUSION: The stimulus of physiologic load can accelerate the early union of allograft-host bone interface and later new bone creep substitution to the necrotic allograft.

Adaptation, Physiological↗

PubMed2001

[The combination of cyclosporin A and androgen in the treatment of chronic aplastic anemia].

OBJECTIVE: To explore the therapeutic effectiveness of combination of cyclosporin A (CsA) and androgen in the treatment of chronic aplastic anemia (CAA). METHOD: Androgen alone or combined with CsA for the treatment of CAA was compared by a randomized controlled clinical trial. RESULT: The efficacy of androgen combined with CsA (87.9%) was higher than that of androgen alone (57.1%). Therapeutic effectiveness of the combination treatment between the patients with positive and negative peripheral blood mononuclear cells (PBMNCs) inhibiting normal colony formation unit-granulocyte and macrophage (CFU-GM) test showed a significant difference (P < 0.005). CONCLUSION: Androgen combined with CsA had a much better efficacy than that of androgen alone in the treatment of CAA. The patients' PBMNCs inhibiting normal CFU-GM growth test can be used as an index of the treatment outcome. The side effects of the combination therapy are low and tolerable.

Adolescent↗

PubMed2001

[Three dimensional quantitative structure activity relationship of P450(17) alpha inhibitors of 17-substituted steroids].

AIM: To develop a three dimensional quantitative structure activity relationship (3D-QSAR) model and gain further insights into the requirements for potential P450(17) alpha inhibitors. METHODS AND RESULTS: A predictive 3D pharmacophore model was established based on comparative molecular field analysis (CoMFA). The correlation between the activities and structures was significant with cross-validated value (R2cv), non-cross-validated value (R2) and standard error of estimate (SEE) of 0.538, 0.799 and 0.257, respectively. According to this model, the predicted inhibition activities of three compounds synthesized in our laboratory were compatible to actual activities. CONCLUSION: This model would contribute to the understanding of the interaction between the inhibitors and P450(17) alpha and rational design of novel lead molecules.

Enzyme Inhibitors↗

PubMed2001

[Fragile X mental retardation protein interacts with human NDK/Nm23-H2].

OBJECTIVE: To investigate the physiological role of fragile X mental retardation protein (FMRP) and screen the proteins interacting with FMRP in human fetal hippocampus cDNA library. METHODS: Human fetal hippocampus cDNA library was constructed in yeast two-hybrid DAD vector pGAD10. Quality of the library was measured by picking up random colonies as templates for PCR testing. Proteins interacting with FMRP were screened by yeast two-hybrid system. Furthermore, the interaction site of FMRP was mapped in yeast. RESULTS: The average length of inserts of the two-hybrid library was 1.5 kb, and the ratio of recombinant colonies was about 90%. Human NDK/Nm23-H2 was found interacting with FMRP. NDK/Nm23-H2 interacted with FMRP exon 1-12, as well as FMRP isoforms without exon 12, and exons 14-17. NDK/Nm23-H2 couldn't interact with FMRP exon 1-6 and exon 2-7 fragments. CONCLUSIONS: Human NDK/Nm23-H2 can bind FMRP directly. The interaction site of FMRP is located at its exon 1-11. This interaction in vitro might alter the intracellular distribution of NDK/Nm23-H2, and even regulates the transcription and expression of FMRP.

Fragile X Messenger Ribonucleoprotein 1↗

PubMed2001

[Determination of 10 elements in the 12 kinds of Chinese traditional medicines by AAS].

The 10 kinds of inorganic elements were determined in 12 kinds of Chinese traditional medicines. The relation showed that there were numerous inorganic elements in the traditional chinese medicines. The relation between these inorganic elements and the efficacies of these medicines was studied and the efficacies of these Chinese traditional medicines were discussed. The efficacies of these traditional medicines were greatly influenced by the content of inorganic elements. To guarantee the efficacies of these traditional medicines, the reasonable control lines concerned with the content of inorganic elements shall be established and the lines will be discussed in the future.

Calcium↗

PubMed2001

[Cell differentiation and down regulation of nm23 gene expression in HL-60 cells induced by 1,25 dihydroxyvitamin D3].

OBJECTIVE: To investigate the differentiation induction effect of 1,25 dihydroxyvitamin D3 on leukemia cell line HL-60 and its mechanisms. METHODS: The changes of proliferation rate and differentiation in HL-60 cells treated with 1,25 dihydroxyvitamin D3 were observed by MTT test, surface marker analysis and NBT reduction reaction, the effects on cell cycle and nm23 gene expression by flow cytometry and RT-PCR. RESULTS: After exposing to 1,25 dihydroxyvitamin D3, the proliferation was inhibited and the cells were induced to differentiate towards more mature monocytes. During differentiation, HL-60 cells were arrested in G1 phase and the expression of nm23 gene was down regulated. CONCLUSION: 1,25 dihydroxyvitamin D3 could induce differentiation of HL-60 cells, this effect might be related to the down regulation of nm23 gene expression.

Calcitriol↗

PubMed2000

Iterative optimal design of PET experiments for estimating beta-adrenergic receptor concentration.

To estimate in vivo myocardial beta-adrenergic receptor concentration with sufficient precision and to reduce the experimental complexities in positron emission tomography (PET), an iterative optimal design method is applied. An initial three-injection protocol, utilising [F-18]-labelled (R)- and (S)-fluorocarazolol and unlabelled (S)-fluorocarazolol, is optimised for ligand dosages and administration times to maximise the precision of all model parameters using the D-optimal criterion. Using this experimental protocol, PET data are collected in porcine studies, and model parameters are estimated. All model parameters are identified with satisfactory precision. The in vivo myocardial beta-receptor concentration is 7.5+/-0.6 pmol x ml(-1), which corresponds to the in vitro result of 10.1+/-1.3 pmol x ml(-1). With more accurate parameter values, a simplified two-injection protocol is optimally designed, utilising only radiolabelled and unlabelled (S)-fluorocarazolol, based on a new criterion to maximise the precision of the beta-receptor concentration. This revised optimum design predicts that the in vivo beta-receptor concentration can be estimated with good precision but reduced experiment complexity.

Adrenergic beta-Antagonists↗

PubMed2000

Isolation and structural elucidation of two new glycosides from sage (Salvia officinalis L.).

Six compounds, 1-O-(2,3, 4-trihydroxy-3-methyl)butyl-6-O-feruloyl-beta-D-glucopyranoside, ethyl beta-D-glucopyranosyl tuberonate, p-hydroxybenzoic acid, (-)-hydroxyjasmonic acid, caffeic acid, and 4-hydroxyacetophenone 4-O-[5-O-(3, 5-dimethoxy-4-hydroxybenzoyl)-beta-D-apiofrunosyl]-(1-->2)-beta-D- glu copyranoside, were isolated from the n-butanol-soluble fraction of sage leaf extracts. Their structures were determined by spectral methods (MS, NMR, and 2D-NMR), and their antioxidant activities were measured. Among them, two new glycosides were elucidated. All of these compounds showed DPPH free radical scavenging activity at the concentration of 30 mM, and caffeic acid was the most active compound.

Free Radicals↗

PubMed2000

Isolation and identification of stilbenes in two varieties of Polygonum cuspidatum.

The roots of two varieties of Polygonum cuspidatum (Hu Zhang and Mexican Bamboo) were analyzed for resveratrol and analogues. The roots of each variety were dried and ground into a powder. The powdered roots were then extracted with methanol and ethyl acetate. The ethyl acetate fraction of the Mexican Bamboo was then subjected to fractionation and purification using silica gel column chromatography and semipreparative HPLC. In addition to resveratrol (3,5,4'-trihydroxystilbene), three stilbene glucosides were identified by (1)H NMR, (13)C NMR, and MS. The stilbene glucosides were shown to be a piceatannol glucoside (3,5,3', 4'-tetrahydroxystilbene 4'-O-beta-D-glucopyranoside), resveratroloside (3,5,4'-trihydroxystilbene 4'-O-beta-D-glucopyranoside), and piceid (3,5,4'-trihydroxystilbene 3-O-beta-D-glucopyranoside). The levels of the piceatannol glucoside and piceid were twice as high in the Mexican Bamboo as compared to the Hu Zhang.

Chromatography, High Pressure Liquid↗

PubMed2000

Identification of oxidation products of (-)-epigallocatechin gallate and (-)-epigallocatechin with H(2)O(2).

(-)-Epigallocatechin gallate (EGCG) and (-)-epigallocatechin (EGC) are two important antioxidants in tea. They also display some antitumor activities, and these activities are believed to be mainly due to their antioxidative effects. However, the specific mechanisms of antioxidant action of tea catechins remain unclear. In this study are isolated and identified two novel reaction products of EGCG and one product of EGC when they were reacted separately with H(2)O(2). These products are formed by the oxidation and decarboxylation of the A ring in the catechin molecule. This study provides unequivocal proof that the A ring of EGCG and EGC may also be an antioxidant site. This study also indicates an additional reaction pathway for the oxidation chemistry of tea catechins.

Antioxidants↗

PubMed2000

Novel glycosides from noni (Morinda citrifolia).

Three new glycosides were isolated from the fruits of noni (Morinda citrifolia). Their structures were determined to be 6-O-(beta-D-glucopyranosyl)-1-O-octanoyl-beta-D-glucopyranose (1), 6-O-(beta-D-glucopyranosyl)-1-O-hexanoyl-beta-D-glucopyranose (2), and 3-methylbut-3-enyl 6-O-beta-D-glucopyranosyl-beta-D-glucopyranoside (3) using MS and NMR methods.

Chromatography, Gel↗

PubMed2000

Cheek cell phospholipids in human infants: a marker of docosahexaenoic and arachidonic acids in the diet, plasma, and red blood cells.

BACKGROUND: Assessment of essential fatty acid status requires collection of blood or adipose tissue samples. However, these invasive techniques cannot always be used in studies involving infants, young children, or subjects from whom it is difficult to obtain blood. A body tissue that is easy to access is the buccal mucosa (cheek cells). OBJECTIVE: The objective was to investigate the degree to which fatty acids of cheek cells reflect the fatty acid content of plasma, red blood cells, and the diet. DESIGN: Thirty-one infants aged 12 mo were enrolled. Five infants were fed human milk and 26 infants received formulas that provided a wide range of arachidonic acid and docosahexaenoic acid (DHA) intakes. Cheek cells were collected on a small piece of gauze by gently swabbing the inside of the cheek 3 times. Lipids were extracted from the gauze and the phospholipid fatty acid content of the cheek cells was determined. RESULTS: Cheek cell DHA and arachidonic acid in phospholipids were significantly correlated with DHA and arachidonic acid in plasma [r = 0.61 (P < 0.001) and r = 0.37 (P <0.05), respectively], red blood cells [r = 0.58 (P < 0.001) and r = 0.37 (P < 0.05), respectively], and the diet [r = 0.65 (P < 0.001) and r = 0. 51 (P < 0.01), respectively]. CONCLUSIONS: Given these correlations and the ease and noninvasive nature of this technique, cheek cell fatty acids may serve as a marker of the essential fatty acid content, especially of DHA and arachidonic acid, in plasma, red blood cells, and the diet.

Analysis of Variance↗

PubMed2000

RNA-Dependent replication and transcription of hepatitis delta virus RNA involve distinct cellular RNA polymerases.

Cellular DNA-dependent RNA polymerase II (pol II) has been postulated to carry out RNA-dependent RNA replication and transcription of hepatitis delta virus (HDV) RNA, generating a full-length (1.7-kb) RNA genome and a subgenomic-length (0.8-kb) mRNA. However, the supporting evidence for this hypothesis was ambiguous because the previous experiments relied on DNA-templated transcription to initiate HDV RNA synthesis. Furthermore, there is no evidence that the same cellular enzyme is involved in the synthesis of both RNA species. In this study, we used a novel HDV RNA-based transfection approach, devoid of any artificial HDV cDNA intermediates, to determine the enzymatic and metabolic requirements for the synthesis of these two RNA species. We showed that HDV subgenomic mRNA transcription was inhibited by a low concentration of alpha-amanitin (<3 microgram/ml) and could be partially restored by an alpha-amanitin-resistant mutant pol II; however, surprisingly, the synthesis of the full-length (1.7-kb) antigenomic RNA was not affected by alpha-amanitin to a concentration higher than 25 microgram/ml. By several other criteria, such as the differing requirement for the de novo-synthesized hepatitis delta antigen and temperature dependence, we further showed that the metabolic requirements of subgenomic HDV mRNA synthesis are different from those for the synthesis of genomic-length HDV RNA and cellular pol II transcripts. The synthesis of the two HDV RNA species could also be uncoupled under several different conditions. These findings provide strong evidence that pol II, or proteins derived from pol II transcripts, is involved in mRNA transcription from the HDV RNA template. In contrast, the synthesis of the 1.7-kb HDV antigenomic RNA appears not to be dependent on pol II. These results reveal that there are distinct molecular mechanisms for the synthesis of these two RNA species.

Animals↗

PubMed2000

[The multimedia molecular biological image processing system].

With the use of computer image processing technology and molecular biological technology, we have developed a new multimedia molecular biological information processing system to detect the characteristic parameter of molecular biological electrophoresis image. The system can determine the macromolecules densities and molecular weight of the DNA amplified fragment or restriction endonuclease hydrolytic fragment protein and other macromolecules. The clinical use and biological application indicate that the system is useful to gene diagnosis and molecular biological researches.

Computational Biology↗

PubMed1999

Hormonal control of protein expression and mRNA levels of the MaxiK channel alpha subunit in myometrium.

Large conductance voltage-dependent and Ca(2+)-modulated K(+) channels play a crucial role in myometrium contractility. Western blots and immunocytochemistry of rat uterine sections or isolated cells show that MaxiK channel protein signals drastically decrease towards the end of pregnancy. Consistent with a transcriptional regulation of channel expression, mRNA levels quantified with the ribonuclease protection assay correlated well with MaxiK protein levels. As a control, Na(+)/K(+)-ATPase protein and RNA levels do not significantly change at different stages of pregnancy. The low numbers of MaxiK channels at the end of pregnancy may facilitate uterine contraction needed for parturition.

Animals↗

PubMed1999

Synthesis and stereochemical assignment of exo- and endo-7-methyl-7-azabicyclo[2.2.1]heptan-2-ol.

[formula: see text] The syntheses of both exo and endo stereoisomers of 7-methyl-7-azabicyclo[2.2.1]heptan-2-ol were achieved in straightforward fashion. Alternatively, the intramolecular cyclization of syn-4-N-methylaminocyclohexane 1,2-epoxide was found to give exo-7-methyl-7-azabicyclo-[2.2.1]heptan-2-ol as the sole product. The stereochemistry of the exo isomer was unequivocally confirmed by X-ray crystallography.

Bridged Bicyclo Compounds, Heterocyclic↗

PubMed1999

Calreticulin expression is associated with androgen regulation of the sensitivity to calcium ionophore-induced apoptosis in LNCaP prostate cancer cells.

Calreticulin has been identified previously as one of the androgen-response genes in the prostate. The role of calreticulin in androgen action was studied using androgen-sensitive LNCaP and androgen-insensitive PC-3 human prostate cancer cell lines. Calreticulin appears to be a primary androgen-response gene in cultured LNCaP cells because androgen induction of calreticulin mRNA resists protein synthesis inhibition. Calreticulin is a high capacity intracellular Ca2+ binding protein, suggesting that calreticulin expression is likely to be associated with the intracellular Ca2+ buffering capacity that could regulate the sensitivity to cytotoxic intracellular Ca2+ overload. As expected, androgen protects androgen-sensitive LNCaP but not androgen-insensitive PC-3 cells from cytotoxic intracellular Ca2+ overload induced by Ca2+ ionophore A23187. To provide evidence for the role of calreticulin in reducing cytotoxic effect of Ca2+ influx in prostatic cells, we have shown that calreticulin antisense oligonucleotide down-regulates calreticulin protein level and significantly increases the sensitivity to A23187-induced apoptosis in both LNCaP and PC-3 cells. Furthermore, calreticulin antisense oligonucleotide reverses the androgen-induced resistance to A23187 in LNCaP cells. The above observations collectively suggest that calreticulin mediates androgen regulation of the sensitivity to Ca2+ ionophore-induced apoptosis in LNCaP cells.

Androgens↗