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Biomedical subjects

Z Liu

Publications and source records attributed to Z Liu.

At least 55 records · Page 3Linked to original sources
PubMed2005

Tear function and goblet cell density after pterygium excision.

PURPOSE: To evaluate the short-term effect of pterygium excision on tear function and conjunctival goblet cell density. METHODS: In all, 70 patients (70 eyes) with primary pterygia who underwent a bare-sclera procedure were enrolled in this study. Tear break-up time, Schirmer, and tear-ferning tests and conjunctival goblet cell density obtained by impression cytology were evaluated before and 1 month after surgery. RESULTS: At 1 month postoperation, the tear break-up time (11.49+/-3.76 s) was significantly prolonged when compared with the preoperation tear break-up time (9.74+/-3.43 s, P=0.002). Before surgery, only 17% of the patients showed normal crystallization in the tear-ferning test. This proportion was significantly increased to 90% 1 month after surgery (P<0.001). There is no significant difference in the Schirmer test value between pre- and postsurgery (P>0.05). The mean goblet cell density in conjunctival impression specimens before surgery was 41.82+/-18.29/10 fields, which was increased significantly 1 month after surgery (P<0.001) with a mean cell density of 50.67+/-18.71/10 fields. CONCLUSION: Tear function in patients with primary pterygium improves after pterygium excision, which indicates that pterygium has a close relationship with dry eye.

Adult↗
PubMed2005

Growth and luminescence of ternary semiconductor ZnCdSe nanowires by metalorganic chemical vapor deposition.

ZnCdSe alloy nanowires were successfully grown on the GaAs (100) substrate by metalorganic chemical vapor deposition using Au as a catalyst. The nanowires display two distinct types of morphology. The majority of them are straight, uniform in diameter, and have a smooth surface. However, a significant portion of them contain one or two constrictions along their length. The alloy is found to be rich in Zn; its composition, as determined from X-ray diffraction and energy-dispersive X-ray microanalysis, is close to Zn(0.9)Cd(0.1)Se. The peak energy of its room temperature near-band-edge photoluminescence is also consistent with this composition. X-ray diffraction pattern and transmission electron microscopy find both types of nanowires to be single crystalline, have the metastable wurtzite structure, and a growth direction along 100. The presence of an Au-Cd-Zn alloy particle at the tip of the nanowires supports vapor-liquid-solid as the growth mechanism. The appearance of constrictions in some of the nanowires is found to be linked to the existence of structural defects, possibly stacking faults, during growth.

Journal Article↗
PubMed2005

Monitoring Chinese hamster ovary cell culture by the analysis of glucose and lactate metabolism.

Monitoring cell growth is crucial to the success of an animal cell culture process that can be accomplished by a variety of direct or indirect methodologies. Glucose is a major carbon and energy source for cultured mammalian cells in most cases, but glycolytic metabolism often results in the accumulation of lactate. Glucose and lactate levels are therefore routinely measured to determine metabolic activities of a culture. Typically, neither glucose consumption rate nor lactate accumulation rate has a direct correlation with cell density due to the changes in culture environment and cell physiology. We discovered that although the metabolic rate of glucose or lactate varies depending on the stages of a culture, the cumulative consumption of glucose and lactate combined (Q(GL)) exhibits a linear relationship relative to the integral of viable cells (IVC), with the slope indicating the specific consumption rate of glucose and lactate combined (q(GL)). Additional studies also showed that the q(GL) remains relatively constant under different culture conditions. The insensitivity of the q(GL) to process variations allows a potentially easy and accurate determination of viable cell density by the measurement of glucose and lactate. In addition, the more predictable nature of a linear relationship will aid the design of better forward control strategies to improve cell culture processes.

Animals↗
PubMed2005

Reduction of insulin-stimulated glucose uptake in L6 myotubes by the protein kinase inhibitor SB203580 is independent of p38MAPK activity.

Insulin increases glucose uptake through translocation of the glucose transporter GLUT4 to the plasma membrane. We previously showed that insulin activates p38MAPK, and inhibitors of p38MAPKalpha and p38MAPKbeta (e.g. SB203580) reduce insulin-stimulated glucose uptake without affecting GLUT4 translocation. This observation suggested that insulin may increase GLUT4 activity via p38alpha and/or p38beta. Here we further explore the possible participation of p38MAPK through a combination of molecular strategies. SB203580 reduced insulin stimulation of glucose uptake in L6 myotubes overexpressing an SB203580-resistant p38alpha (drug-resistant p38alpha) but barely affected phosphorylation of the p38 substrate MAPK-activated protein kinase-2. Expression of dominant-negative p38alpha or p38beta reduced p38MAPK phosphorylation by 70% but had no effect on insulin-stimulated glucose uptake. Gene silencing via isoform-specific small interfering RNAs reduced expression of p38alpha or p38beta by 60-70% without diminishing insulin-stimulated glucose uptake. SB203580 reduced photoaffinity labeling of GLUT4 by bio-LC-ATB-BMPA only in the insulin-stimulated state. Unless low levels of p38MAPK suffice to regulate glucose uptake, these results suggest that the inhibition of insulin-stimulated glucose transport by SB203580 is likely not mediated by p38MAPK. Instead, changes experienced by insulin-stimulated GLUT4 make it susceptible to inhibition by SB203580.

Animals↗
PubMed2005

Synthesis, characteristics and biological activity of pentacoordinated spirophosphoranes derived from amino acids.

The reactions of phosphorus trichloride with various amino acids afford the pentacoordinated spirophosphoranes. The reaction procedures were traced by (31)P NMR spectra techniques. A new crystal structure of alanine derivative was characterized, which is a slightly distorted TBP structure. Besides, this kind of spirophosphoranes are potent inhibitors to tyrosinase.

Amino Acids↗
PubMed2005

Engineering and characterisation of chimeric monoclonal antibody 806 (ch806) for targeted immunotherapy of tumours expressing de2-7 EGFR or amplified EGFR.

We report the generation of a chimeric monoclonal antibody (ch806) with specificity for an epitope on the epidermal growth factor receptor (EGFR) that is different from that targeted by all other anti-EGFR therapies. Ch806 antibody is reactive to both de2-7 and overexpressed wild-type (wt) EGFR but not native EGFR expressed in normal tissues at physiological levels. Ch806 was stably expressed in CHO (DHFR -/-) cells and purified for subsequent characterisation and validated for use in preliminary immunotherapy investigations. Ch806 retained the antigen binding specificity and affinity of the murine parental antibody. Furthermore, ch806 displayed enhanced antibody-dependent cellular cytotoxicity against target cells expressing the 806 antigen in the presence of human effector cells. Ch806 was successfully radiolabelled with both iodine-125 and indium-111 without loss of antigen binding affinity or specificity. The radioimmunoconjugates were stable in the presence of human serum at 37 degrees C for up to 9 days and displayed a terminal half-life (T(1/2beta)) of approximately 78 h in nude mice. Biodistribution studies undertaken in BALB/c nude mice bearing de2-7 EGFR-expressing or amplified EGFR-expressing xenografts revealed that (125)I-labelled ch806 failed to display any significant tumour retention. However, specific and prolonged tumour localisation of (111)In-labelled ch806 was demonstrated with uptake of 31%ID g(-1) and a tumour to blood ratio of 5 : 1 observed at 7 days postinjection. In vivo therapy studies with ch806 demonstrated significant antitumour effects on established de2-7 EGFR xenografts in BALB/c nude mice compared to control, and both murine 806 and the anti-EGFR 528 antibodies. These results support a potential therapeutic role of ch806 in the treatment of suitable EGFR-expressing tumours, and warrants further investigation of the potential of ch806 as a therapeutic agent.

Animals↗
PubMed2005

Cardioprotective effects of peroxisome proliferator activated receptor gamma activators on acute myocarditis: anti-inflammatory actions associated with nuclear factor kappaB blockade.

OBJECTIVE: To test the hypothesis that activation of peroxisome proliferator activated receptor gamma (PPAR-gamma) reduces experimental autoimmune myocarditis (EAM) associated with inhibitor kappaB (IkappaB) alpha induction, blockade of nuclear factor kappaB (NF-kappaB), and inhibition of inflammatory cytokine expression. METHODS: EAM was induced in Lewis rats by immunisation with porcine cardiac myosin. PPAR-gamma activators 15-deoxy-Delta(12,14)-prostaglandin J2 (15d-PGJ2) and pioglitazone (PIO) were administered to rats with EAM. RESULTS: Enhanced PPAR-gamma expression was prominently stained in the nuclear and perinuclear regions of infiltrating inflammatory cells. Administration of 15d-PGJ2 and PIO greatly reduced the severity of myocarditis and suppressed myocardial mRNA and protein expression of inflammatory cytokines in rats with EAM. In addition, treatment with PPAR-gamma activators enhanced IkappaB concentrations in the cytoplasmic fractions and nuclear fractions from inflammatory myocardium. Concurrently, NF-kappaB was greatly activated in myocarditis; this activation was blocked in the 15d-PGJ2 treated and PIO treated groups. CONCLUSIONS: PPAR-gamma may have a role in the pathophysiology of EAM. Because an increase in IkappaB expression and inhibition of translocation of the NF-kappaB subunit p65 to the nucleus in inflammatory cells correlated with the protective effects of PPAR-gamma activators, these results suggest that PPAR-gamma activators act sequentially through PPAR-gamma activation, IkappaB induction, blockade of NF-kappaB activation, and inhibition of inflammatory cytokine expression. These results suggest that PPAR-gamma activators such as 15d-PGJ2 and PIO may have the potential to modulate human inflammatory heart diseases such as myocarditis.

Acute Disease↗
PubMed2005

Clinical research on monitoring CSFP through lumbar epidural pressure.

OBJECTIVE: Explore the relationship between lumbar Epidural Pressure (LEDP) and CSFP through clinical studies and to determine whether LEDP can represent CSFP. METHODS: We selected 150 cases of cerebral diseases at random for this study. A special mini transducer was implanted into the lumbar epidural space between the third and the 4th lumbar vertebra by means of a No. 18 Touhy needle for monitoring of LEDP. In the meantime, a traditional lumbar puncture was made between the 4th and the 5th lumbar vertebrae and CSFP, which was taken as the standard value, was measured using an ordinary catheter. The transducer was adjusted until the LEDP was equal to CSFP and was designated LEDP0. The LEDP0 was monitored continuously and was translated into a continuous curve. In each and every case, a lumbar puncture was repeated at 24, 48, 72 and 96 hours to obtain CSFP for comparison and to explore the relationship between LEDP0 and CSFP. While monitoring LEDP0, we observed the variation in pressure when the patient breathed, coughed, changed posture, and also if the clinical symptoms changed with intracranial hypertension. RESULT: The values of the intracranial pressure measured by these two methods were identical. CONCLUSION: LEDP responded to the changes of CSFP.

Adolescent↗
PubMed2005

Striatal dopamine level increases in the urinary storage phase in cats: an in vivo microdialysis study.

Parkinson's disease is a common neurodegenerative disease that shows not only movement disorder, but also profound urinary dysfunction. Bladder hyperactivity is the major urodynamic abnormality. Therefore, the basal ganglia have been thought to modulate the micturition reflex. In six male adult cats under ketamine anesthesia, in which spontaneous isovolumetric micturition reflexes had been generated, we measured levels of striatal dopamine, in micturition and storage phases, using in vivo microdialysis. The striatal dopamine level significantly increased in the storage phase as compared with that in the micturition phase. It is suggested that striatal dopamine may inhibit the micturition reflex via the dopamine D1 receptor-GABAergic direct striatal output pathway, and that disruption of this pathway may be what leads to bladder hyperactivity in patients with Parkinson's disease.

Animals↗
PubMed2005

Variation of CD4+ and CD8+ T lymphocytes as predictor of outcome in renal allograft recipients who developed acute respiratory distress syndrome caused by cytomegalovirus pneumonia.

INTRODUCTION: We investigated the variation of CD4+ and CD8+ T lymphocytes in renal allograft recipients who developed acute respiratory distress syndrome (ARDS) caused by cytomegalovirus (CMV) infection and their relationship to patients outcome. METHODS: Twenty one cadaveric renal allograft recipients who developed ARDS caused by CMV infection were enrolled in this study. CD4+ and CD8+ T lymphocytes were examined in peripheral blood on five occasions: the admission day (day 0) to ICU as ARDS, day 5, day 10, day 15 in ICU, and discharge day. A value taken in the second month after transplantation was assumed to be the preinfection value. RESULTS: Among 13 surviving patients, the numbers of CD4+ and CD8+ T cells and their ratio increased as the patients recovered. The numbers of CD4+ T cells increased significantly on day 10, day 15, and at discharge day compared with day 0 (P < .05). The number of CD8+ T cells on discharge day and the ratios after day 10 were also significantly higher than those on day 0 (P < .05). In eight nonsurviving patients, the numbers of CD4+ and CD8+ T cells and their ratio was similar to day 0. The number of CD4+ and CD8+ cells after day 5 and their ratio after day 10 were significantly lower than those of survival group (P < .05). CONCLUSION: The variations of CD4+ and CD8+ T lymphocytes and their ratio are useful indicators of the severity of disease and the outcome of patients with CMV infections accompanying ARDS after renal transplantation. Nevertheless, it may be helpful to evaluate the efficiency of ongoing treatment methods in these patients.

CD4 Lymphocyte Count↗
PubMed2005

Two-layer method in short-term pancreas preservation for successful islet isolation.

BACKGROUND: We sought to determine whether the two-layer method (TLM) offers advantages over UW storage solution for locally procured pancreata with cold ischemia time of <8 hours for successful islet isolation. METHODS: From October 2003 through February 2005, 22 human pancreata were procured locally from cadaveric donors and preserved using UW solution (n = 11) or TLM (n = 11). RESULTS: Donor characteristics were similar in the two groups, with no statistical difference. Cold ischemia time was 4.5 +/- 0.6 (2.5 to 8) hours in the UW and 5.1 +/- 0.5 (3 to 8) hours in TLM group (P > .05). Organs preserved with TLM were exposed to PFC for 4 +/- 0.5 (2 to 7.5) hours. After TLM preservation, 8 of 11 (72%) pancreata yielded >300,000 IEQ pancreatic islets, which met all criteria for clinical transplantation; after UW cold storage, only 3 of 11 isolations were equally successful (27%) (P < .05). Mean IEQ was higher in the TLM than in the UW group: 349,000 +/- 37,000 vs 277,800 +/- 34,000; IEQ/g was also higher at 5100 +/- 760 vs 3000 +/- 570, respectively (P < .05). Islet quality, characterized by purity, viability, and insulin SI, did not differ statistically in the two groups: 67 +/- 4 vs 74 +/- 4%, 87 +/- 2 vs 83 +/- 4%, and 4 +/- 0.7 vs 4.8 +/- 1, respectively (P > .05). CONCLUSIONS: The Two Layer Method for locally procured human pancreata with cold ischemia time lower than 8 hours offers significant advantage over UW cold storage increasing the pancreatic islet isolation yield and the isolation success rate.

Adenosine↗
PubMed2005

Late developing C4d-positive humoral renal allograft rejection associated with withdrawal of mycophenolate mofetil.

In renal transplantation, C4d-positive acute humoral rejection (AHR) usually develops in the early stage posttransplantation. It is clear C4d can be detected late after the operation, when it is associated with chronic renal allograft rejection. We report a case of a renal allograft recipient who experienced C4d-positive acute renal allograft rejection associated with withdrawal of mycophenolate mofetil (MMF) at 10 months after transplantation. This 21-year-old single male patient received his first cadaveric renal allograft under immunosuppression with cyclosporine, MMF, and prednisolone. The serum creatinine recovered to the normal range within 4 days. A protocol biopsy performed at 1 month after transplantation revealed no signs of rejection. The graft function was stable until 10 months postoperation, when MMF was converted to mizoribin. Three days later a biopsy showed a C4d-positive rejection. Patient had no response to the MMF combined with tacrolimus and steroid bolus therapy, which generally improves 85% of AHR among Chinese. He finally returned to dialysis. Our report suggested that C4d positive AHR may occur late after transplantation. MMF is important to suppress the body's humoral response to allograft; when MMF was converted to a weaker immunosuppressant, the dose of the other immunosuppressants (cyclosporine for example) must be adjusted properly.

Acute Disease↗
PubMed2005

Tylosin sorption to silty clay loam soils, swine manure, and sand.

The objectives of this study were to assess sorption and desorption of tylosin, a macrolide antimicrobial chemical used in swine, cattle, and poultry production, in three silty clay loam soils of South Dakota and compare soil sorption to sand and manure sorption. The silty clay loam soils, from a toposequence in eastern South Dakota, standardized sand samples, and swine manure were used in 24-h batch sorption studies with tylosin concentrations ranging from 25 to 232 micro mole/L. Desorption from soil was conducted over a four-day period. Partition coefficients, based on the Freundlich isotherm (K(f)) or K(d) values, were calculated. K(f) values for the silty clay loams were similar, not influenced by landscape position, and averaged 1,350 with isotherm slopes ranging from 0.85 to 0.93. K(f) values for sand were dependent on solution/sand ratios and pH, ranging from 1.4 to 25.1. K(d) values of manure were dependent on the solution type and ranged from 840 L/kg with urine to about 175 L/kg when sorbed from water. Desorption of tylosin from each soil over the four-day period was < 0.2% of the amount added. The soils' high K(f) values and low desorption amounts suggest that once tylosin is in these soils, leaching to lower depths may not occur. However, this does not preclude runoff with soil eroded particles. If tylosin reaches a sand aquifer, through bypass flow or other mechanism(s), movement in the aquifer most likely would occur.

Adsorption↗
PubMed2005

Potent in vivo anti-tumor activity of isolated CD62L(low) lymph node cells sensitized in vivo with tumor lysate-pulsed DC-based vaccines.

BACKGROUND: DC are potent APC that can activate both CD4 and CD8 T cells in vitro and in vivo. Although the efficacy of DC-based cancer vaccines is currently being evaluated in clinical trials, the systemic immune suppression in cancer patients negatively impacts the clinical benefit of this therapeutic approach. Therefore, in this study we tested the feasibility and anti-tumor effect of adoptive immunotherapy using in vitro-activated CD62L(low) lymph node cells that were isolated from DC-vaccinated draining lymph nodes (VDLN). METHODS: DC were prepared from BM cells and loaded with tumor lysate for inoculating into naive mice. Subsequently, the VDLN were removed and CD62L(low) cells in the VDLN population isolated, expanded in vitro by 5-day culture with IL-2 and immobilized anti-CD3 stimulation, then injected into mice with established pulmonary tumors. Eighteen days after treatment, mice were killed in order to enumerate pulmonary tumor nodes. RESULTS: DC phagocytosed the tumor lysate efficiently and induced detectable T-cell responses and significant cell expansion in the draining lymph nodes. After induction of maturation by LPS treatment, DC expressed higher levels of CD40, CD86 and MHC class II molecules. When CD62L(low) VDLN cells that had been isolated and expanded in vitro were transferred into tumor-bearing mice, as few as 3 x 10(6) cells were able to cure metastatic pulmonary tumors in vivo. DISCUSSION: DC-based VDLN T cells are an important source of anti-tumor effector for adoptive immunotherapy. This study provides a novel and an effective protocol using T-cell adoptive immunotherapy for application in cancer patients; therefore, clinical trials based on this protocol may be warranted.

Animals↗
PubMed2005

Highly conserved gene expression profiles in humans with allergic rhinitis altered by immunotherapy.

BACKGROUND: Atopic diseases, resulting from hypersensitivity to a wide variety of allergens, affect 10-20% of the population. Immunotherapy is an effective treatment for atopic diseases, but its mechanisms are not fully understood. OBJECTIVE: We studied gene expression profiles in the peripheral blood mononuclear cells (PBMC) and examined whether the individuals with allergic rhinitis (AR) have a unique gene expression profile and how the immunotherapy affect the gene expression profiles. METHODS: We used cDNA microarray and 'expression analysis systemic explorer' to examine the gene expression profiles in the PBMC of atopic subjects and other groups. RESULTS: We identified a highly conserved gene expression profile in atopic subjects that permitted their accurate segregation from control or autoimmune subjects. A major feature of this profile was the under-expression of a variety of genes that encode proteins required for apoptosis and over-expression of genes that encode proteins critical for stress responses and signal transduction. We also identified 563 genes that can segregate individuals with AR based upon receipt of immunotherapy. CONCLUSION: There is a highly conserved gene expression profile in the PBMC of individuals with AR. This profile can be used to identify individuals with AR and to evaluate responses to immunotherapy. Quantitative endpoints, such as gene expression, may assist clinicians faced with clinical decisions in the diagnosis of patients and the evaluation of response to therapy. The knowledge of the possible genetic basis for immunotherapy efficacy may also lead to novel therapeutic approaches for atopic diseases.

Adult↗
PubMed2005

Immobilization and condensation of DNA with 3-aminopropyltriethoxysilane studied by atomic force microscopy.

We used different methods to modify a mica surface with 3-aminopropyltriethoxysilane (APTES), and then used it as substrate to immobilize DNA for atomic force microscopy (AFM) observation. The evaporation method and solution modifying method were investigated and evaluated. The solution modifying method was found to be relatively simple and effective. Using an APTES solution-modified mica surface, DNA immobilization appeared more reproducible and it could be imaged in liquid. The mixed solution of APTES and DNA was dropped directly onto the mica surface for AFM imaging. We found that DNA can condense in APTES water solutions. Toroids, rods and intermediate structures of condensation were captured by AFM.

DNA↗