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Biomedical subjects

Jun Zhu

Publications and source records attributed to Jun Zhu.

177 records · Page 10Linked to original sources
PubMed2002

Stratification of solids, nitrogen and phosphorus in swine manure in deep pits under slatted floors.

Manure slurries stored in pits under slatted floors of both finishing and nursery barns were sampled at four different depths to study stratifications of total solids (TS) and nutrients (nitrogen and phosphorus), and to determine the relationship between the stratification of TS and nutrients. The results obtained can be used to improve the management and handling of swine manure in the under-slat storage pits. A management scheme that can be adopted for both the finishing and the nursery barns' pits is the layer-by-layer harvesting of the manure. The thinner manure, which is lower in nutrients, can be spread on land near the production units in larger volumes or it may pumped to land remote from the production units without causing many clogging problems. The thicker manure, higher in nutrients, can be transported to land further away and spread in smaller volumes. The TS content of each stratum can be used to accurately estimate the nitrogen and phosphorus levels in the respective strata so that application rates can easily be adjusted accordingly during the time of land application.

Age Factors↗
PubMed2002

How acute promyelocytic leukaemia revived arsenic.

Despite its many therapeutic qualities, arsenic trioxide has been more commonly remembered as Madame Bovary's poison than as an anticancer drug. The ability of arsenic trioxide to treat acute promyelocytic leukaemia has radically changed this view, providing new insights into the pathogenesis of this malignancy and raising hopes that arsenicals might be useful in treating other cancers.

Animals↗
PubMed2002

Bacterial responses to temperature during aeration of pig slurry.

The temperature effect on total anaerobic and aerobic bacterial growth in pig slurry was studied using low level batch aeration treatments. Five bioreactors were built using Plexiglas tubes to perform five temperature treatments (5 degrees C, 10 degrees C, 15 degrees C, 20 degrees C, and 25 degrees C). An airflow rate of 0.129 L/min/L manure was used to aerate manure contained in all reactors. Data showed that temperature had a profound impact on the aerobic counts in pig slurry during the aeration process. When the temperature increased from 15 degrees C to 25 degrees C, the average oxidation-reduction potential decreased from +40 mV to -60 mV, accompanied by a 75% reduction of aerobic bacteria in the manure. At 25 degrees C, the anaerobic counts were consistently higher than aerobic counts for most of days. A quadratic relationship was observed between the aerobic counts and the oxidation-reduction potential with a correlation coefficient of 0.8374. To reduce odor generation potential, the oxidation-reduction potential in the manure should be maintained at +35 mV or higher.

Aerobiosis↗
PubMed2002

Nuclear export and retention signals in the RS domain of SR proteins.

Splicing factors of the SR protein family share a modular structure consisting of one or two RNA recognition motifs (RRMs) and a C-terminal RS domain rich in arginine and serine residues. The RS domain, which is extensively phosphorylated, promotes protein-protein interactions and directs subcellular localization and-in certain situations-nucleocytoplasmic shuttling of individual SR proteins. We analyzed mutant versions of human SF2/ASF in which the natural RS repeats were replaced by RD or RE repeats and compared the splicing and subcellular localization properties of these proteins to those of SF2/ASF lacking the entire RS domain or possessing a minimal RS domain consisting of 10 consecutive RS dipeptides (RS10). In vitro splicing of a pre-mRNA that requires an RS domain could take place when the mutant RD, RE, or RS10 domain replaced the natural domain. The RS10 version of SF2/ASF shuttled between the nucleus and the cytoplasm in the same manner as the wild-type protein, suggesting that a tract of consecutive RS dipeptides, in conjunction with the RRMs of SF2/ASF, is necessary and sufficient to direct nucleocytoplasmic shuttling. However, the SR protein SC35 has two long stretches of RS repeats, yet it is not a shuttling protein. We demonstrate the presence of a dominant nuclear retention signal in the RS domain of SC35.

3T3 Cells↗
PubMed2002

Mapping epigenetic quantitative trait loci (QTL) altering a developmental trajectory.

Genetic variation in a quantitative trait that changes with age is important to both evolutionary biologists and breeders. A traditional analysis of the dynamics of genetic variation is based on the genetic variance-covariance matrix among different ages estimated from a quantitative genetic model. Such an analysis, however, cannot reveal the mechanistic basis of the genetic variation for a growth trait during ontogeny. Age-specific genetic variance at time t conditional on the causal genetic effect at time t - 1 implies the generation of episodes of new genetic variation arising during the interval t - 1 to t. In the present paper, the conditional genetic variance estimated from Zhu's (1995) conditional model was partitioned into its underlying individual quantitative trait loci (QTL) using molecular markers in an F2 progeny of poplars (Populus trichocarpa and Populus deltoides). These QTL, defined as epigenetic QTL, govern the alterations of growth trajectory in a population. Three epigenetic QTL were detected to contribute significantly to variation in growth trajectory during the period from the establishment year to the subsequent year in the field. It is suggested that the activation and expression of epigenetic QTL are influenced by the developmental status of trees and the environment in which they are grown.

Analysis of Variance↗
PubMed2002

[Developmental genetic analysis for transparency of rice (Oryza sativa L.) at different environments].

The developmental behavior of gene expression for transparency of rice (TR) was analyzed from two-year experimental data at different filling stages by using both conditional and unconditional analysis methods for quantitative traits of seeds in cereal crops. It was revealed that the gene expression was most active for the performance of TR at the middle and late filling stages (8-21 d after flowering). The differences of expression at different environments for triploid endosperm nuclear genes, cytoplasmic genes and diploid maternal plant nuclear genes were found for the performance of TR. The phenomena of which some genetic effects were spasmodically expressible were detected among filling stages of rice. Because of the higher additive and cytoplasmic effects along with their interaction effects for TR at the filling stages, the better improving effects for this trait could be expected by selection in rice breeding. Some parents such as Zhenan 3 and 1391 were better than others for improving TR.

Environment↗
PubMed2002

DNA immunization with recombinant HCV E2 expression plasmids.

DNA-based immunization, the delivery of plasmid DNA by direct inoculation, is a newly developed method of vaccination. Besides of many advantages, DNA immunization was demonstrated to generate weaker antibody and CTL responses than did protein and live attenuated vaccines, respectively. To circumvent this shortage, several methods were tested such as using different vector, changing injection mode, and co-expressing cytokines, etc. The studies showed that many factors could greatly affect the immune responses to DNA vaccine. The aim of this study is to compare different vectors for the presentation of the HCV E2 to generate immune responses by using DNA-based immunization. Four expression plasmids, with different promoter types and with or without signal sequences were constructed, which encode C-terminally truncated E2 (384-660) with HBV preS1 21-47 tag fused to its N-termini. Transient expression in HeLa cells showed that only recombinant plasmids with signal sequence could be expressed and properly processed, and the product could be secreted into medium. Protein expression level is slightly higher in plasmids with CMV promoter than with EF1alpha promoter. After immunization of C57BL/6 mice, all the recombinant constructs could elicit both anti-preS1 and anti-E2 antibodies. But only pCMV Sec-S1E2t660 with both CMV promoter and signal sequence could induce high-level and long-lasting antibody, showing that it is a good vaccine candidate. Possible reasons for the different immune responses to these constructs were discussed.

Animals↗
PubMed2002

[Clinical study of rhIL-11 for prevention and treatment of chemotherapy-induced thrombocytopenia].

BACKGROUND AND OBJECTIVE: Cancer chemotherapy can induce thrombocytopenia. It is necessory to develop drugs that can prevent and treat thrombocytopenia. The current study was designed to evaluate the efficacy and toxicity of rhIL-11 in prevention and treatment of chemotherapy-induced thrombocytopenia. METHOD: A total of 109 cancer patients were involved randomly into AB or BA group and every patient received 2 cycles of chemotherapy. IL-11 was administered subcutaneously(50 micrograms/kg/d), beginning 24 hours after completion of chemotherapy for 14 consecutive days or continuing until platelet count was > 400 x 10(9)/L during cycle A. Patients did not received IL-11 during cycle B. Another 41 cases of cancer patients whose platelet were less than 50 x 10(9)/L after chemotherapy entered into open study group. IL-11 administration was the same as above. RESULTS: Efficacy can be evaluated in 107 cases in controlled study group. Mean platelet count of cycle A was (246.49 +/- 88.64) x 10(9)/L and cycle B was (180.24 +/- 83.34) x 10(9)/L(P = 0.000). Grade III/IV thrombocytopenia in cycle A and cycle B were 7/107(6.5%) and 15/107(14%), respectively (P = 0.04). The minimum platelet counts were (136.46 +/- 74.64) x 10(9)/L and (107.77 +/- 61.33) x 10(9)/L, respectively (P = 0.000). The maximum platelet counts were (381.28 +/- 150.39) x 10(9)/L and (207.44 +/- 113.32) x 10(9)/L, respectively (P = 0.000). For open study group, 32 patients could be evaluated. The platelet count increased from(30.1875 +/- 12.13) x 10(9)/L to (226.25 +/- 163.91) x 10(9)/L after IL-11 administration. Major adverse effects were edema, dizziness, palpitation, etc. CONCLUSION: rhIL-11 can reduce thrombocytopenia induced by chemotherapy and is a safe and effective drug for treatment of thrombocytopenia.

Adult↗
PubMed2002

[An epidemiological investigation of perinatal teratomas in China].

OBJECTIVE: To investigate the prevalence rate and epidemiological features of teratomas in China. METHODS: From 1987 through 1992, hospital-based cluster sampling method was adopted for collecting data. During that period all live or still births with 28 weeks of gestation or more were assessed within 7 days after delivery. RESULTS: 238 teratoma cases were identified in 4,489,692 births, including 198 isolated and 40 associated forms of teratomas. The prevalence rates of total teratomas, isolated and associated forms of teratomas were 0. 53/10000, 0.44/10000, 0.09/10000 respectively. The prevalence rates in urban areas and rural areas were 0.46/10000 and 0.66/10000, respectively. The prevalence rates of teratomas in male and female births were 0.80/10000 and 0.27/10000 correspondingly. The ratio of male to female teratomas was 1:2.76. The perinatal fatality rate of teratomas was 55.0%. CONCLUSION: The most frequent teratomas were isolated forms. Time trends have not been found in the occurrence of teratomas. High prevalence in urban areas has been observed, compared to that in rural areas. The prevalence of teratomas in female births is three times as high as that in male births. In view of the high fatality rate, prenatal diagnosis and perinatal management of teratomas should be strengthened.

China↗
PubMed2002

[Dynamic monitoring of neural tube defects in China during 1996 to 2000].

OBJECTIVE: The database from Chinese Birth Defects Monitoring Network was used to describe the epidemiological features and secular trends of neural tube defects (NTDs) prevalence during Jan. 1996 to Dec. 2000, including anencephaly, spina bifida and encephalocele. METHODS: Data were collected with hospital-based cluster sampling method. During the period, all live or still births with 28 weeks or more of gestation were assessed within seven days after delivery. RESULTS: There were 2 873 case with NTDs identified from 2 281 616 births, with an overall prevalence rate of 12.95 per 10,000 births. And, the prevalence rates of anencephaly, spina bifida and encephalocele were 5.02 per 10,000, 6.30 per 10,000 and 1.64 per 10,000, respectively. Significant falls in overall prevalence rates of NTDs and of anencephaly were observed. The prevalence rates of NTDs were 9.75 per 10,000 and 15.96 per 10,000 in male and female births, respectively, 7.76 per 10,000 and 25.20 per 10,000 in the urban and rural areas, respectively, and 19.90 per 10,000 and 5.81 per 10,000 in north and south China, respectively. The prevalence was higher in the groups with maternal age of less than 20 years and more than 30 years than in those other maternal ages. Preterm babies and babies with low birth weight accounted for 50.9% and 50.6% of perinatal babies with NTDs, respectively, with a perinatal mortality of 77.8%. CONCLUSIONS: In China, the occurrence of NTDs was higher in female births than in male births, higher in the rural than in the urban, and higher in the north than in the south. Annual prevalence rate of NTDs in China presented a declining trend, but still higher than that in the other countries at the same time period. Babies with NTDs were in poor birth quality, higher perinatal mortality and poor prognosis. Effective preventive measures and prenatal diagnosis should be strengthened to reduce the occurrences of neural tube defects.

Adult↗
PubMed1989

Sympathetic facilitation of sustained discharges of polymodal nociceptors.

Injection of a compound algogenic substance into a receptive field of the skin induced sustained discharges from single polymodal nociceptors (PMNs) in rats. Stimulation of the sympathetic nerve (SS) innervating the receptive field obviously increased the sustained discharges. Some units were first facilitated and then inhibited. The sympathetic effect could be activated repeatedly and lasted a long time. Injection of norepinephrine (NE, 5 micrograms) into the local artery caused a similar effect. The results indicate that the sympathetic nerve could facilitate sustained discharges of PMN. The possible causes of causalgia and different results of other experiments are discussed in this paper.

Action Potentials↗
PubMedDate not supplied

Rho and ROCK signaling in VEGF-induced microvascular endothelial hyperpermeability.

OBJECTIVES: Vascular endothelial growth factor (VEGF) plays an important role in the regulation of microvascular permeability under various physiological and pathological conditions. The authors tested the hypothesis that the small GTPase Rho and its downstream effector ROCK (Rho-associated coiled-coil-containing protein kinase) mediate VEGF-induced increases in venular permeability. They also investigated myosin light chain (MLC) phosphorylation and actin polymerization, two well-characterized targets of the Rho-ROCK pathway that are implicated in the regulation of endothelial barrier function. METHODS: The apparent permeability coefficient of albumin (P(a)) was measured in intact isolated porcine coronary venules and in cultured coronary venular endothelial cell (CVEC) monolayers. RhoA activation was determined using a Rhotekin-agarose pull down assay. MLC phosphorylation was evaluated by immunoblotting with phospho-specific antibodies, and endothelial cellular F-actin was viewed using fluorescence microscopy. RESULTS: VEGF increased P(a) in both isolated coronary venules and CVEC monolayers. The hyperpermeability response occurred in a similar time course to that of Rho activation, MLC phosphorylation, and actin stress fiber formation. Selective blockage of ROCK with Y27632 dose-dependently inhibited VEGF-induced venular hyperpermeability. Moreover, inhibition of either Rho with exoenzyme C3 or ROCK with Y-27632 attenuated VEGF-induced increases in permeability, MLC phosphorylation, and actin-stress fiber formation in CVEC monolayers. CONCLUSIONS: Collectively, these findings suggest that the Rho-ROCK signal pathway contributes to VEGF-induced hyperpermeability. Myosin light-chain phosphorylation and actin stress fiber formation occur concomitantly with the increase in permeability upon VEGF stimulation.

Albumins↗
PubMedDate not supplied

Enhanced apoptotic effects of novel paclitaxel analogs on NCI/ADR-RES breast cancer cells.

This study aimed to investigate the apoptotic effects of novel paclitaxel analogs on NCI/ADR-RES breast cancer cells. Using the colony formation assay, the cytotoxicity of three novel paclitaxel analogs were evaluated on NCI/ADR-RES cells which overexpress multidrug-resistant gene (MDR1). All three novel paclitaxel analogs exhibited significantly higher cytotoxicity on NCI/ADR-RES cells than paclitaxel. One analog, TL139, was 140 times more effective than paclitaxel. Using TUNEL and DNA fragmentation assay, remarkably increased apoptosis in the paclitaxel analog-treated cells was observed at 48-72 hours, but not in paclitaxel-treated cells. Caspases-3/7 were dramatically activated at 48-72 hours by the novel paclitaxel analogs. The enhanced activity of caspases-3/7 was evidently verified by the measurement of the cleavage of poly(ADP-ribose) polymerase (PARP). The increased activity of caspases-3/7 significantly correlated with the enhanced apoptosis and cell survival data. Treatment with paclitaxel analogs resulted in a significant amount of mitotic arrest. Using Western blot, the phosphorylation of Bcl-2 protein was found in palictaxel analog-treated cells in a time-dependent manner similar to that of mitotic arrest, thereby indicating that there existed a close correlation between Bcl-2 phosphorylation and mitotic arrest that preceded apoptosis. We conclude that novel taxane analogs could effectively kill MDR1-positive breast cancer cells via the mode of apoptosis.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMedDate not supplied

Centrosome impairments and consequent cytokinesis defects are possible mechanisms of taxane drugs.

Taxol and taxotere are two of the most promising anticancer drugs. To determine the mechanisms responsible for cell death after exposure to low doses of taxane, PC3 cells were treated with taxol and taxotere, and observed with immunofluoroscence microscopy. Pericentriolar material dissociation and blockage of normal centrosome separation were found to result in two different abnormal spindle types; multipolar and monopolar spindles, respectively. The majority of abnormal spindles induced by taxol were monopolar spindles, whereas taxotere mostly induced abnormal multipolar spindles. Consequently, monopolar spindle mitosis resulted in cleavage failure, while multipolar spindle mitosis led to the formation of both cleavage failure and multipolar cell division. Multinucleation characterized interphase cells which had undergone cytokinesis defects. These cells subsequently became giant multinucleated cells after several rounds of cell cycle with sustained cleavage failure, and were gradually eliminated through cell death.

Antineoplastic Agents, Phytogenic↗