Biomedical subjects

Y Zeng

Publications and source records attributed to Y Zeng.

At least 19 recordsLinked to original sources

PubMed2006

A 3D analysis of oxygen transfer in a low-cost micro-bioreactor for animal cell suspension culture.

A 3D numerical model was developed to study the flow field and oxygen transport in a micro-bioreactor with a rotating magnetic bar on the bottom to mix the culture medium. The Reynolds number (Re) was kept in the range of 100-716 to ensure laminar environment for animal cell culture. The volumetric oxygen transfer coefficient (k(L)a) was determined from the oxygen concentration distribution. It was found that the effect of the cell consumption on k(L)a could be negligible. A correlation was proposed to predict the liquid-phase oxygen transfer coefficient (k(Lm)) as a function of Re. The overall oxygen transfer coefficient (k(L)) was obtained by the two-resistance model. Another correlation, within an error of 15%, was proposed to estimate the minimum oxygen concentration to avoid cell hypoxia. By combination of the correlations, the maximum cell density, which the present micro-bioreactor could support, was predicted to be in the order of 10(12) cells m(-3). The results are comparable with typical values reported for animal cell growth in mechanically stirred bioreactors.

Animals↗

PubMed2006

Principles of micro-RNA production and maturation.

Micro-RNAs (miRNAs) are a class of approximately 22-nucleotide non-coding RNAs expressed in multicellular organisms. They are first transcribed in a similar manner to pre-mRNAs. The transcripts then go through a series of processing steps, including endonucleolytic cleavage, nuclear export and a strand selection procedure, to yield the single-stranded mature miRNA products. The transcription and processing of miRNAs determines the abundance and the sequence of mature miRNAs and has important implications for the function of miRNAs.

Animals↗

PubMed2006

Fluorescence-based monitoring of tracer and substrate distribution in an UASB reactor.

In this work, rhodamine-related fluorescence was measured on-line at four reactor heights in order to study hydrodynamics within an upflow anaerobic sludge bed reactor. A linear dependence of the dispersion coefficient (D) on the upflow velocity was observed, while the influence of the organic loading rate (OLR) was insignificant. Furthermore, the Bodenstein number of the reactor loaded with granulated sludge was found to be position-dependent with the largest values measured at the bottom of the sludge bed. This trend was not observed in the reactor without sludge. Chemical oxygen demand (COD) and volatile fatty acid (VFA) concentrations were measured at the same reactor heights as in rhodamine tests using conventional off-line analytical methods and on-line multiwavelength fluorometry. Significant spatial COD and VFA gradients were observed at organic loading rates above 6g COD l(R)(-1)d(-1) and linear upflow velocities below 0.8m h(-1).

Bioreactors↗

PubMed2006

Gene expression signatures and biomarkers of noninvasive and invasive breast cancer cells: comprehensive profiles by representational difference analysis, microarrays and proteomics.

We have characterized comprehensive transcript and proteomic profiles of cell lines corresponding to normal breast (MCF10A), noninvasive breast cancer (MCF7) and invasive breast cancer (MDA-MB-231). The transcript profiles were first analysed by a modified protocol for representational difference analysis (RDA) of cDNAs between MCF7 and MDA-MB-231 cells. The majority of genes identified by RDA showed nearly complete concordance with microarray results, and also led to the identification of some differentially expressed genes such as lysyl oxidase, copper transporter ATP7A, EphB6, RUNX2 and a variant of RUNX2. The altered transcripts identified by microarray analysis were involved in cell-cell or cell-matrix interaction, Rho signaling, calcium homeostasis and copper-binding/sensitive activities. A set of nine genes that included GPCR11, cadherin 11, annexin A1, vimentin, lactate dehydrogenase B (upregulated in MDA-MB-231) and GREB1, S100A8, amyloid beta precursor protein, claudin 3 and cadherin 1 (downregulated in MDA-MB-231) were sufficient to distinguish MDA-MB-231 from MCF7 cells. The downregulation of a set of transcripts for proteins involved in cell-cell interaction indicated these transcripts as potential markers for invasiveness that can be detected by methylation-specific PCR. The proteomic profiles indicated altered abundance of fewer proteins as compared to transcript profiles. Antisense knockdown of selected transcripts led to inhibition of cell proliferation that was accompanied by altered proteomic profiles. The proteomic profiles of antisense transfectants suggest the involvement of peptidyl-prolyl isomerase, Raf kinase inhibitor and 80 kDa protein kinase C substrate in mediating the inhibition of cell proliferation.

Biomarkers, Tumor↗

PubMed2006

Concentrations of extracellular free zinc (pZn)e in the central nervous system during simple anesthetization, ischemia and reperfusion.

"Free Zn2+" (rapidly exchangeable Zn2+) is stored along with glutamate in the presynaptic terminals of specific specialized (gluzinergic) cerebrocortical neurons. This synaptically releasable Zn2+ has been recognized as a potent modulator of glutamatergic transmission and as a key toxin in excitotoxic neuronal injury. Surprisingly (despite abundant work on bound zinc), neither the baseline concentration of free Zn2+ in the brain nor the presumed co-release of free Zn2+ and glutamate has ever been directly observed in the intact brain in vivo. Here, we show for the first time in dialysates of rat and rabbit brain and human CSF samples from lumbar punctures that: (i) the resting or "tonic" level of free Zn2+ signal in the extracellular fluid of the rat, rabbit and human being is approximately 19 nM (95% range: 5-25 nM). This concentration is 15,000-fold lower than the "300 microM" concentration which is often used as the "physiological" concentration of free zinc for stimulating neural tissue. (ii) During ischemia and reperfusion in the rabbit, free zinc and glutamate are (as has often been presumed) released together into the extracellular fluid. (iii) Unexpectedly, Zn2+ is also released alone (without glutamate) at a variable concentration for several hours during the reperfusion aftermath following ischemia. The source(s) of this latter prolonged release of Zn2+ is/are presumed to be non-synaptic and is/are now under investigation. We conclude that both Zn2+ and glutamate signaling occur in excitotoxicity, perhaps by two (or more) different release mechanisms.

Anesthetics↗

PubMed2006

Experimental study on in vitro tumor cell killing by focused bi-frequency ultrasound activated hematoporphyrin derivatives.

OBJECTIVE: As ultrasound has become an important therapeutic technique on tumor, in order to find the cell-killing effect of focused bi-frequency ultrasound activated hematoporphyrin derivatives, experimental study was processed in vitro. METHODS: Tumor cells K562 and SW-480 were killed by focused bi-frequency ultrasound activated hematoporphyrin (Hp) derivatives under optimized ultrasonic parameters and the cell-killing effect was tested by MTT (Thiazolyl blue: 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide) technique. RESULTS: The lower frequency (0.6 MHz) was better than the higher (1.1 MHz) in activating hematoporphyrin derivatives; the bi-frequency was better than mono-frequency, and the cell-killing efficiency was 2-3 times of sum of the two kinds of ultrasounds which constitute bi-frequency. Incubation for the 16 h was better than 4 h after the cells exposed to the ultrasound. CONCLUSION: The method of killing tumor cells by focused bi-frequency ultrasound activated hematoporphyrin derivatives is presented and evaluated in this paper.

Apoptosis↗

PubMed2006

An apparatus for studying the response of cultured endothelial cells to stresses.

In order to simulate the hemodynamic environment of human arteries in vivo, we designed a laminar flow apparatus which can precisely simulate the normal stress and shear stress to which cultured endothelial cells are exposed. Under both normal and abnormal physiological conditions, this apparatus can accurately control and adjust the values of normal stress and shear stress and the frequency of pulse waves, as well as the amplitude of pulsatile flow. This in vitro apparatus provides an experimental platform for studying the response of the biological characteristics of cultured endothelial cells in a hemodynamic environment.

Blood Flow Velocity↗

PubMed2006

Construction and characterization of a cDNA library from liver tissue of Chinese Banna minipig inbred line.

A xenograft that performs efficient functions is an essential premise for successful xenotransplantation. Our early study indicated that Chinese Banna minipig inbred line (BMI) was an ideal xenograft donor. However, the activities of some proteins synthesized by the BMI liver are different from the human, which could lead to functional disorders in coagulation, fibrinolysis, and anticoagulation after liver xenotransplantation. Therefore, it is important to investigate the genetic background of protein incompatibility and to provide new strategies for gene manipulation. In this study we constructed a cDNA expression library using BMI liver tissue to obtain an understanding of nucleic acid and protein differences between the two species. We extracted total RNA and purified mRNA of the liver tissue from one of the sixteenth inbred generation of BMI/JS 151 substrain. After double-strand cDNA synthesis, we fractionated it on a CHROMA APIN-400 column; ligated the longer than 500bp cDNA into a ZAP Express Vector; and performed a lambda: phage packaging reaction, library amplification, and titer. We randomly picked 12 plaques and tested the length of inserts. The titers of the primary and amplified libraries were 1.0 x 10(6) pfu/mL and 5.0 x 10(9) pfu/mL, respectively. The percentages of recombinants were 97.0% in the primary library and 98.0% in the amplified library. The lengths of most inserts were between 750 bp and 2.0 kb. Thus, we successfully constructed a cDNA expression library from BMI liver tissue. Using the library, we hope to get a full-length cDNA of some important genes and conduct further studies on porcine liver function in xenotransplantation.

Animals↗

PubMed2006

Factors related to post-liver transplantation acute renal failure.

Acute renal failure (ARF) after liver transplantation (OLT) is a common complication with severe impact on early and late prognosis of recipients. Factors predicting its incidence have not been fully identified due to the lack of a universal standard as well as the variance of data between transplant centers. To identify factors related to post-OLT ARF, we retrospectively collected materials on 89 patients, who underwent OLT from 1999 to 2001 in our center. Factors associated with post-OLT ARF were identified using univariate logistic regression. Significant factors were then entered into a multivariate logistic regression to identify factors independently associated with post-OLT ARF. Upon univariate analysis, intraoperative volume of blood transfusion (P = .041) and duration of operation (P = .005) were significant. ARF was associated with a poor prognosis (P < .001). Only duration of operation (P = .026) was an independent factor predicting the development of ARF. In conclusion, intraoperative volume of blood transfusion and duration of operation were factors contributing to post-OLT ARF in which the duration of the operation was an independent risk factor. The incidence of post-OLT ARF greatly increased recipient mortality in the early postoperative period.

Acute Kidney Injury↗

PubMed2006

Postoperative severe pneumonia in adult liver transplant recipients.

Severe pneumonia in adult liver transplantation (OLT) recipients is a dangerous condition with significant morbidity and mortality. To analyze the risk factors for postoperative severe pneumonia in OLT patients, we collected data from 132 consecutive adult patients who underwent OLT between February 1999 and April 2004. According to the American Thoracic Society consensus statement, episodes of severe pneumonia were observed in 24 patients (18.2%). We retrospectively reviewed the etiology diagnosis, treatment, and prognosis of the 24 recipients. Bacteria were responsible for 95.8% of these episodes (23 of 24), fungi for 16.7% (4 of 24) and viruses for 4.4% (1 of 24). Twenty-six percent of the bacterial pneumonias were due to Streptococcus alpha hemolyticus. The mortality rate was 37.5% (9 of 24) for patients with severe pneumonia versus 7.4% (8 of 108, P = .004) for patients without pneumonia. Two cases with hepatorenal syndrome died, and three patients with coinfection by bacteria and fungi died. Acute rejection episodes occurred in 15 patients, four of whom died. Mechanical ventilation and tracheotomy were required in 13 cases (54%). Six who experienced prolonged intubation died. Sputum and pleural fluid cultures helped to establish a diagnosis in 91.7% (22 of 24) of cases. Twenty cases (83%) underwent reduction in the immunosuppressive regimen. Patient age, intraoperative transfusion requirements, extubation time, and hospital stay were fatal predictors of prognoses. We concluded that early detection of the responsible pathogen; timely and specific diagnosis; reduction in the immunosuppressive regimen; appropriate treatment with reliable, effective techniques; and implementation of sensitive culture-based antibiotics was an effective strategy to treat severe adult pneumonia in liver transplantation recipients.

Adult↗

PubMed2006

Enrichment for microbes living in association with plant tissues.

AIMS: To investigate a cultivation-independent method of enrichment for microbes living in association with plant tissues. METHODS AND RESULTS: A large quantity of leaves or seeds was enzymatically hydrolyzed, and the pellets were collected by differential centrifugation. Enzyme concentration, buffer and incubation time were optimized for release of plant-associated microbes. The relative abundance of plant nuclear DNA and bacterial DNA in the enriched sample was estimated by PCR amplification of genome-specific marker genes. The efficiency of microbe enrichment was estimated from the proportion of bacterium-derived clones and their restriction fragment length polymorphism (RFLP) types as detected by 16S rRNA gene-based techniques. With a higher ratio of bacterial to plant nuclear DNA, the enriched samples showed a considerably enhanced proportion of bacterium-derived clones and a wider sequence diversity of those clones. CONCLUSIONS: The method described here proved to be remarkably effective in enriching for bacteria living in association with plant tissues. SIGNIFICANCE AND IMPACT OF THE STUDY: The method can be applied to study plant-associated microbes in the field of environmental molecular ecology and environmental metagenomics.

Cell Nucleus↗

PubMed2006

Monoclonal antibody to tumor necrosis factor-related apoptosis-inducing ligand receptor 2 (TRAIL-R2) induces apoptosis in primary renal cell carcinoma cells in vitro and inhibits tumor growth in vivo.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) triggers apoptosis in a variety of tumor cells through two of its receptors: TRAIL-R1 and TRAIL-R2. We investigate the susceptibility of human renal cell carcinoma (RCC) cells to TRM-1 and HGS-ETR2, 2 human monoclonal agonistic antibodies specific for TRAIL-R1 and TRAIL-R2, respectively. HGS-ETR2 effectively induced apoptotic cell death in 10 of 11 cell cultures, including 2 human RCC cell lines and 9 human primary RCC cell cultures, with a more pronounced effect after preincubation with anti-human IgG Fc. In contrast, TRM-1 was effective in only 1 primary RCC cell culture. The increased effectiveness of HGS-ETR2 for inducing cell death might have been affected by differences in the cell-surface expression of the 2 TRAIL receptors, namely that TRAIL-R2 but not TRAIL-R1 was frequently expressed in most of the RCC cells tested. The activities of caspase-9, -8, -6, and -3 were increased with HGS-ETR2-induced apoptosis, and cell death could be blocked by specific caspase inhibitors for caspase-9, -8, and -3, and the general caspase inhibitor. In vivo administration of HGS-ETR2 with or without cross-linker significantly suppressed tumor growth of subcutaneously inoculated human RCC xenografts in immunodeficient mice. These results suggest the potential utility of TRAIL-R2 antibody as a novel therapeutic agent in RCC.

Animals↗

PubMed2006

[Synergistic effects of human papillomavirus and phorbol ester in cell transformation.].

BACKGROUND: To investigate the molecular mechanism of the synergistic effects of human papillomavirus (HPV) and phorbal esters (TPA) in cell transformation. METHODS: The expression of oncogenes and anti-oncogenes in 293 cell line treated with HPV and TPA was studied by Southern Blot and RNA dot blot. RESULTS: It was found that the synergistic effect induced the amplification of c-myc (4-8 times), increased expressing level of c-erbB-2 (32-64 times) and decreased expressing level of p16(1/4-1/8). CONCLUSION: The above results show that the synergistic effect has an important role in development of carcinoma.

Cell Line↗

PubMed2006

[Comparison of IgA/VCA, IgA/EA, IgG/EA in immunoenzyme methods and ZEBRA ELISA in early diagnosis of nasopharyngeal carcinoma.].

BACKGROUND: To develop an ELISA method using Herpesvirus hominis type 4 (EBV) IgG/Zebra as capture antigen for large population screening. METHODS: The ELISA method used purified ZEBRA antigen to detect the IgG/ZEBRA antibody from serum in nasopharyngeal carcinoma (NPC) and normal healthy subjects. RESULTS: Of 288 NPC sera, 262 were detected positive, the sensitivity was 91%, while 5 of 96 normal sera were detected positive, the specificity was 94.8% and the results of NPC group and healthy group displayed significant difference (P less than 0.001). IgA/VCA, IgA/EA, IgG/EA in immunoenzyme methods and ZEBRA ELISA were compared during the NPC screening in two cities: Huizhou, Guangdong and Guiping, Guangxi, 5463 and 2017 samples respectively were tested and 5 earlier NPC patients were found. CONCLUSION: The results indicate that this method has high specificity and sensitivity, and can be used for large population screening to assist early phase NPC diagnosis.

Animals↗

PubMed2005

Interfacial interaction of tartaric acid with hydroxyapatite and enamel.

The purpose of this study was to investigate the interfacial interaction of tartaric acid with hydroxyapatite and enamel. Hydroxyapatite particles were mixed with 15% (w/v) alcohol-aqueous (1:1) solution of tartaric acid for 72 h. After the mixture, the filtrate was separated from the solid. The filtrate, the solid, hydroxyapatite, and tartaric acid were dried for FTIR and XRD analysis. Enamel disks etched with tartaric acid for 60 s were analyzed by attenuated total reflectance (ATR). Enamel disks etched with 15% tartaric acid for 15, 30, 60, 120 s were analyzed by SEM. FTIR spectra showed carboxylate in the solid and in subtraction spectra. ATR spectra revealed carboxylate on the enamel surfaces. XRD data indicated the formation of calcium tartrate and calcium hydrogen phosphate after the reaction of tartaric acid with hydroxyapatite. SEM observations revealed typical decalcification of the periphery of the enamel rods due tartaric acid etching. It is concluded that tartaric acid can decalcify and chemisorb onto HA simultaneously, hence, tartaric acid could be used as etchant and ingredient of self-etching primers in adhesive dentistry.

Acid Etching, Dental↗

PubMed2005

Orthotopic liver transplantation for incurable alveolar echinococcosis: report of five cases from west China.

Alveolar echinococcosis of the liver, caused by the larval stage of Echinococcus multilocularis, has the characteristics of a slow-growing liver cancer. The aim of the present work was to report a series of patients who received orthotopic liver transplantation (OLT) for life-threatening disease. Our article summarizes the medical history, diagnosis, treatment, and prognosis of five patients who received OLT between 2001 and 2002. Most patients had a long history of symptomatic disease (iterative cholangitis, obstructive jaundice) and repeated abdominal surgery. One patient died during the hospitalization mostly related to bacterial infection and multiple organ failure. Another accidental death happened 3 months later from heart failure. Three patients are alive in good condition verifying that OLT is a feasible option for these end-stage cases. In general, combination therapy-chemotherapy, interventional therapy, radical surgery or/and OLT at an early stage-is proposed in advanced cases of which OLT has clearly played a vital role. Despite major technical difficulties, OLT for incurable disease is feasible. Specific management is needed to improve the results: earlier decision for OLT in symptomatic disease, routine pre- and post-transplant therapy, reduced immunosuppression, and regular follow-up.

Adolescent↗

PubMed2004

Screening and analysis of porcine endogenous retrovirus in Chinese Banna minipig inbred line.

Pigs have been the most likely animal as the source of cells, tissues, and organs for xenotransplantation. But the use of pigs in xenotransplantation is associated with the risk of porcine endogenous retrovirus (PERV) transmission. Previous studies have identified that the proviruses are integrated into the genome of normal pigs and that virus particles released from the porcine cells can infect human cells in vitro. As a unique inbred pig, Banna minipig inbred (BMI) has a huge potential value for xenotransplantation and medical research. It has been the focal experimental animal for pig-to-human xenotransplantation in China, due to its clear genetic background and tiny individual differences. To evaluate whether the potential risk of PERV exists in inbred pigs, a series of screening experiments were performed herein. The results of PCR with primers specific for gag, pol, and env showed that proviruses existed in the genome of BMI, and the PERV subtypes were PERV-A and PERV-B. PERV mRNA was expressed functionally in BMI. Positive results of an RT assay identified that PERV in BMI had potential infectivity, but the concentration of PERV reverse transcriptase in BMI was almost 20 times lower than that of HIV. These results suggested that gag, pol and env genes of PERV were not lost during inbreeding, which created favorable conditions to produce viral particles that could possibly infect human cells in xenotransplantation.

Animals↗

PubMed2004

Phylogenetic analysis of porcine endogenous retrovirus variation in three Chinese pigs.

PCR amplification was performed on genomic DNA extracted from peripheral blood lymphocytes of three species of Chinese pigs (Banna minipig inbreed [BMI], Wu-Zhi-Shan pig [WZSP], and Nei jiang pig [NJP]), using primers corresponding to the highly conserved regions of polymerase (pol) gene. Extracted PCR products were then cloned in a pGEM-T vector. Phylogenetic analysis of the nucleotide sequences of BMI-PERV, NJJP-PERV, and WZSP-PERV revealed them to be a novel category of PERV. In comparison to other type C retrovirus and lentivirus, their amino acid sequenced show about 30% to 57.7% identities. Our previous research demonstrated that PERV in the three pigs was highly expressed. It appears likely that functional loci encoding these novel PERV sequences exist, but this remains to be established. The novel sequences described in this report will allow such investigations to be actively pursued.

Animals↗