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Biomedical subjects

Z Liu

Publications and source records attributed to Z Liu.

At least 37 records · Page 2Linked to original sources
PubMed2006

Validation of the scoring system for standardization of the pancreatic donor for islet isolation as used in a new islet isolation center.

BACKGROUND: The aim of this study was to evaluate the effectiveness of the Edmonton Donor Scoring System for use in our much less active islet center. Because the ability to recognize an appropriate donor may help to achieve consistent and predictable success of pancreatic islet isolation, it should lead to increased effectiveness and lower cost. MATERIAL AND METHODS: Charts of 36 consecutive pancreas donors were reviewed to assess the donor points (DP). DP ranged from 0 to 100 based on donor age, body mass index, cause of death, social and medical history, hospital stay, vasopressor dosages, laboratory tests, cold ischemia time and procurement team, as well as pancreas size, consistency, fat content, damage, and quality of procurement and packing. RESULTS: Successful isolation was achieved in 39% of donors (14 of 36), a value similar to that achieved in Edmonton (40%). We used the optimal cutoff value (DP = 79) proposed by the Edmonton group. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 66%, 75%, 57%, 82% and 72%, respectively. Successful islet isolation from poor or marginal donors (DP < 49.5 and 50 to 59.5) was 0% and 28.6% respectively; it was 63% and 100% in optimal donors (DP = 80 to 89.5 and 90 to 100). We concluded that islet isolation success correlated with the previously proposed donor scoring system. CONCLUSIONS: The Donor Scoring System can be successfully implemented regardless of the level of activity of an experienced isolation center. This system permits identification of a suitable donor prior to organ processing. It may guide a center's donor selection strategy based on its goals and its budget.

Adult↗
PubMed2006

Comparison of Natuphos and Phyzyme as phytase sources for commercial layers fed corn-soy diet.

The objective of this experiment was to compare the effects of 2 sources of phytase on performance of commercial Leghorns fed corn-soy diets. Seven diets were fed to Hy-line W-36 hens (n = 840; 8 replicates of 15 hens per treatment) from 21 to 33 wk of age. The treatments consisted of a control diet containing 0.38% nonphytate P (NPP) and a 2 x 3 factorial arrangement of 2 dietary NPP concentrations (0.11 and 0.26%) with 2 phytase sources [Natuphos (BASF, Mt. Olive, NJ) and Phyzyme (Danisco Animal Nutrition, Carol Stream, IL)] and without phytase. Dietary NPP had significant effects on feed intake, NPP intake, total P intake, egg production, egg weight, egg mass, egg specific gravity, and excreta P. The addition of Phyzyme or Natuphos significantly increased egg production and egg mass of hens fed the P-deficient diet (0.11% NPP) to levels that were similar to hens fed the control diet containing 0.38% NPP. Feed intake of hens fed the diets supplemented with Phyzyme or Natuphos was significantly less than that of hens fed the control diet containing 0.38% NPP. Phyzyme or Natuphos supplementation in the diets containing 0.11% NPP had significantly reduced excreta P of the control diet (approximately 58 and 54%, respectively) with no adverse effect on egg production and egg mass. There were no significant differences in feed intake, NPP intake, total P intake, egg production, egg weight, egg mass, feed conversion, egg specific gravity, mortality, BW, and excreta P between the diets supplemented with Natuphos and the diets supplemented with Phyzyme. In conclusion, Phyzyme had the same positive effects on performance of commercial Leghorns fed corn-soy diets as Natuphos.

6-Phytase↗
PubMed2006

Channel catfish BAC-end sequences for marker development and assessment of syntenic conservation with other fish species.

In the present study, 25 195 BAC ends for channel catfish (Ictalurus punctatus) were sequenced, generating 20 366 clean BAC-end sequences (BES), with an average read length of 557 bp after trimming. A total of 11 414 601 bp were generated, representing approximately 1.2% of the catfish genome. Based on this survey, the catfish genome was found to be highly AT-rich, with 60.7% A+T and 39.3% G+C. Approximately 12% of the catfish genome consisted of dispersed repetitive elements, with the Tc1/mariner transposons making up the largest percentage by base pair (4.57%). Microsatellites were detected in 17.5% of BES. Catfish BACs were anchored to the zebrafish and Tetraodon genome sequences by BLASTN, generating 16% and 8.2% significant hits (E < e(-5)) respectively. A total of 1074 and 773 significant hits were unique to the zebrafish and Tetraodon genomes, respectively, of which 417 and 406, respectively, were identified as known genes in other species, providing a major genome resource for comparative genomic mapping.

Animals↗
PubMed2006

Enhanced immunogenicity and antitumour effects with heterologous prime-boost regime using vaccines based on MG7-Ag mimotope of gastric cancer.

MG7-Ag, gastric cancer-associated antigen, has been shown to be immunogenic and has been used as marker molecule for prognosis. In a previous study, we developed an oral DNA vaccine based on MG7-Ag mimotope. However, we failed to detect cellular immune response using the oral MG7-Ag mimotope DNA vaccine. To induce significant T cell response, we developed a recombinant adenovirus vaccine based on MG7-Ag mimotope and evaluated the efficacy and protective effects of heterologous prime-boost immunization protocol with an oral DNA vaccine previously developed. We found that both vaccines were able to elicit a significant humoral response against MG7-Ag, while the highest serum titre MG7 antibody was detected in mice immunized with the heterologous prime-boost immunization protocol. Enzyme-linked immunospot (ELISPOT) assay demonstrated that the heterologous prime-boost immunization strategy was more efficient in inducing T cell response than the homologous prime-boost strategy. In the tumour challenge assay, 2 of 5 mice immunized with the heterologous prime-boost protocol were tumour free, while none of the mice in homologous prime-boost groups or control groups was tumour free. Those tumour-bearing mice in the heterologous prime-boost regime had smaller tumour masses than their counterparts in the homologous prime-boost groups or control groups. Therefore, our study suggests that vaccines against MG7-Ag induce significant immune response against gastric cancer, and that the heterologous prime-boost protocol using different types of vaccines could achieve better protective effect than the homologous prime-boost protocol.

Adenoviridae↗
PubMed2006

Cardiac troponin I and ventricular arrhythmia in patients with chronic heart failure.

BACKGROUND: Both detectable serum cardiac troponin I (cTnI) and ventricular dysrhythmias are common in patients with chronic heart failure (CHF) and are paralleled with the severity of the CHF. However, the relationship between serum cTnI and ventricular arrhythmia severity in patients with CHF remains unknown; the mechanism of the ventricular arrhythmia in the CHF patients also remains unclear. MATERIALS AND METHODS: The study group included 218 patients with CHF who had cTnI assay drawn at the time of initial presentation. Patients with acute myocardial infarction or myocarditis were excluded from the analysis. The patients were divided into two groups: cTnI-positive with serum cTnI > 0.5 ng mL(-1) (n = 98) and cTnI-negative with serum cTnI < or = 0.5 ng mL(-1) (n = 120). The severity of ventricular dysrhythmias was assessed by 24-h Holter monitoring, using prospectively defined measures of ventricular arrhythmic burden. RESULTS: Prevalence of risk factors for ventricular dysrhythmias was equal in both groups. All measures of ventricular ectopy were much higher in patients of the cTnI-positive groups. Mean hourly ventricular pairs (13.59 +/- 10.3 vs. 11.1 +/- 6.01, P = 0.027), mean hourly repetitive ventricular beats (26.01 +/- 13.67 vs. 22.01 +/- 13.56, P = 0.032), and the frequency of ventricular tachycardia episodes per 24 h (12.54 +/- 16.68 vs. 7.68 +/- 11.54, P = 0.012) were higher in patients with detectable cTnI levels. After inclusion of clinical variables and drug therapies in a multivariate analysis, the positive relationship between cTnI and the frequency of ventricular pairs (P = 0.03), repetitive ventricular beats (P = 0.037), and ventricular tachycardia (P = 0.03) remained independent. In multivariate logistic regression, the risk of developing ventricular tachycardia was higher in patients with detectable cTnI levels with an adjusted odds ratio (OR) of 2.31 (95% CI, 1.22-2.65, P = 0.003). CONCLUSIONS: In patients with CHF, serum cTnI is closely related to increased occurrence of ventricular dysrhythmias and could identify a subgroup of patients with ventricular tachycardia. The minimal myocardial injury detected by serum cTnI might be the abnormal substrate for ventricular dysrhythmias.

Arrhythmias, Cardiac↗
PubMed2006

Effect of flow regimes on the presence of Legionella within the biofilm of a model plumbing system.

AIMS: Stagnation is widely believed to predispose water systems to colonization by Legionella. A model plumbing system was constructed to determine the effect of flow regimes on the presence of Legionella within microbial biofilms. METHODS AND RESULTS: The plumbing model contained three parallel pipes where turbulent, laminar and stagnant flow regimes were established. Four sets of experiments were carried out with Reynolds number from 10,000 to 40,000 and from 355 to 2,000 in turbulent and laminar pipes, respectively. Legionella counts recovered from biofilm and planktonic water samples of the three sampling pipes were compared with to determine the effect of flow regime on the presence of Legionella. Significantly higher colony counts of Legionella were recovered from the biofilm of the pipe with turbulent flow compared with the pipe with laminar flow. The lowest counts were in the pipe with stagnant flow. CONCLUSIONS: We were unable to demonstrate that stagnant conditions promoted Legionella colonization. SIGNIFICANCE AND IMPACT OF THE STUDY: Plumbing modifications to remove areas of stagnation including deadlegs are widely recommended, but these modifications are tedious and expensive to perform. Controlled studies in large buildings are needed to validate this unproved hypothesis.

Bacterial Adhesion↗
PubMed2006

Wavelength division scanning for two-photon excitation fluorescence imaging.

We investigate wavelength division scanning for two-photon excitation fluorescence imaging. Two-photon imaging using lateral wavelength division scanning is demonstrated. In addition, we theoretically analyse the spatial and temporal properties of a femtosecond laser beam focused by a Fresnel lens and investigate the feasibility of axial scanning using wavelength division.

Microscopy, Confocal↗
PubMed2006

Interleukin-21 induces T-cell activation and proinflammatory cytokine secretion in rheumatoid arthritis.

Interleukin (IL)-21 is a CD4+ T-cell-derived cytokine, which is involved in innate and adaptive immune response. In this study, we analysed IL-21 receptor (IL-21R) expression in peripheral blood and synovial fluid mononuclear cells, and investigated the role of IL-21 in the induction of proinflammatory cytokine production by peripheral blood T cells (PB-T) and synovial fluid T cells (SF-T) from patients with rheumatoid arthritis (RA). Immunohistochemical staining demonstrated that IL-21R-positive cells were significantly increased in inflamed synovial tissues of RA patients compared with osteoarthritis (OA) and healthy controls. Flow cytometric analysis confirmed that IL-21R was mainly expressed in freshly isolated CD4, CD8, B and NK cells from peripheral blood and synovial fluid, but decreased gradually in T cells 24 h after anti-CD3 stimulation. PB- and SF-T cells from RA patients were more responsive to IL-21 when compared with controls. Importantly, isolated PB- or SF-T cells from RA patients, when stimulated with IL-21 and anti-CD3 MoAb, secreted markedly higher levels of TNF-alpha and IFN-gamma than controls. These data indicate that IL-21R is overexpressed in the inflamed synovial membrane and in peripheral blood or synovial fluid leukocytes of RA patients, and that IL-21 enhances local T-cell activation, proliferation and proinflammatory cytokine secretion. Thus, blockade of IL-21R signalling pathway may have a therapeutic potential in acute RA patients.

Adolescent↗
PubMed2006

Polymorphism of HLA class II genes in Miao and Yao nationalities of Southwest China.

In the present study, the polymorphism of human leucocyte antigen class II genes was investigated by the sequence-based typing method in two Chinese populations: the Miaos (n = 85) from Guizhou province and the Yaos (n = 66) from Yunnan province. These two populations exhibited certain similarity in their allelic distributions. Among 24 DRB1 alleles detected, DRB1*150101, DRB1*140101, DRB1*160201 and DRB1*090102 in Miao and DRB1*120201, DRB1*140101, DRB1*150101 and DRB1*090102 in Yao were highly predominant. Sixteen DQB1 alleles in total were found in these two populations among which DQB1*050201, DQB1*060101/060103 and DQB1*030101/0309 in both Miao and Yao and DQB1*050301 in Yao were commonly observed. In the 13 DPB1 alleles detected, the most frequent allele was DPB1*0501 in Miao and Yao followed by DPB1*02 and DPB1*1301. Frequent comparisons with other Chinese populations suggested the southern Chinese feature for both the Miao and Yao nationalities.

Alleles↗
PubMed2006

Combined use of 16S ribosomal DNA and automated ribosomal intergenic spacer analysis to study the bacterial community in catfish ponds.

AIMS: To apply culture-independent techniques to explore the bacterial community composition in catfish pond water. METHODS AND RESULTS: 16S rDNA libraries were constructed and sequenced from 15 pond water samples. Automated ribosomal intergenic spacer analysis (ARISA) was used to fingerprint each bacterial community. A broad diversity in bacterial species composition was found by 16S rDNA analysis. Alphaproteobacteria was the most represented class in all ponds, followed by Gammaproteobacteria and Gram-positive high G + C content bacteria. Uniqueness of bacterial communities from each individual pond was confirmed by ARISA. Catfish pathogens were detected sporadically. CONCLUSIONS: Bacterial communities in a catfish aquaculture setting can vary from pond to pond at one given point. No correlation could be made between bacteria composition and fish strain or between bacterial profile and the presence of catfish pathogens in a particular pond. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report showing the composition of bacterial communities in catfish ponds. Fish health specialists and catfish aquaculture managers should be aware of the wide differences in bacterial communities between ponds and include this variable in fish husbandry practices.

Animals↗
PubMed2006

Neutralizing IL-7 promotes long-term allograft survival induced by CD40/CD40L costimulatory blockade.

Memory T cells are somewhat resistant to immunosuppresion. They therefore pose a threat to inducing long-term allograft survival. IL-7 is essential for memory T-cell generation. Here, we investigated whether neutralizing IL-7 promotes allograft survival. We found that neutralizing IL-7 alone did not significantly prolong allograft survival. However, blocking both IL-7 and CD154 signaling synergistically prolonged allograft survival. In contrast, neutralizing IL-2 failed to further prolong allograft survival induced by CD40/CD154 costimulatory blockade. Allospecific memory CD8+ T-cell generation was severely impaired under the treatment of anti-IL-7 plus anti-CD154 Ab while administering recombinant IL-7 enhanced CD8+ memory generation even under donor-specific transfusion plus anti-CD154 Ab treatment. Neutralizing IL-7, but not IL-2, together with blocking CD154 synergistically suppressed the proliferation of naïve/effector CD8+ T cells infiltrating grafts. Nevertheless, neutralizing IL-7 did not alter regulatory T-cell generation while neutralizing IL-2 suppressed their generation. Hence, targeting IL-7 represents a new strategy to prolong allograft survival by acting on both naïve and memory T cells. Long-term allograft survival may be achieved by neutralizing IL-7 plus CD40/CD154 blockade, since CD40/CD154 costimulatory blockade prevents acute rejection while neutralizing IL-7 suppresses the generation of memory T cells that persist and mediate late or chronic rejection.

Animals↗
PubMed2006

Ultrasound biomicroscopy of Chinese eyes with iridocorneal endothelial syndrome.

AIM: To document the ultrasound biomicroscopic (UBM) findings in Chinese patients with iridocorneal endothelial (ICE) syndrome. METHODS: 21 patients with ICE syndrome and 15 normal subjects underwent UBM. UBM findings of anterior segment were compared between normal subjects and three clinical types of ICE syndrome: progressive iris atrophy (PIA), Chandler's syndrome (CS), and Cogan-Reese syndrome (CRS). RESULTS: Central anterior chamber depth was significantly less in patients with ICE syndrome (2.25 (SD 0.32) mm) than in normal subjects (2.76 (0.32) mm). Peripheral anterior synechiae were observed in all the ICE patients by UBM. Three out of four CRS subjects showed an "arborised" shape of iridocorneal angle. Two eyes out of 10 with CS presented bridge-shaped synechiae. A membrane-like mound was observed in iridocorneal angle in two patients: one with CRS and one with CS. UBM was found to be more effective in detecting peripheral anterior synechiae (PAS) and iris atrophy than slit lamp microscopy and gonioscopy, mainly because of corneal oedema in patients with CS. Four out of 11 patients with unilateral ICE syndrome had shallow or closed anterior chamber angles in their fellow eyes. Two of them successfully responded to laser peripheral iridotomy. CONCLUSIONS: UBM is an effective method to reveal the anterior segment features and provides a useful tool in the diagnosis of ICE syndrome. Different subtypes of ICE syndrome may have different UBM manifestations. UBM can help to identify angle closure in the fellow eye of unilateral ICE syndromes.

Adult↗
PubMed2006

Nicotinic signal transduction machinery.

Nicotinic synapses employ acetylcholine to activate ligand-gated ion channels that are cation-selective in vertebrates. Although the resulting nicotinic cholinergic transmission is famously excitatory at the neuromuscular junction, it plays many additional roles in the CNS. Most prevalent is that of modulation, usually involving calcium and signal transduction. Because of this, it is becoming increasingly important not only to understand the mechanisms that guide nicotinic receptors to appropriate locations but also to identify the postsynaptic machinery making possible the requisite signal transduction. Clearly, the kinds of components tethered in the vicinity of the receptor will assume a major role in determining the consequences of receptor activation. One of the most abundant and interesting nicotinic receptors in this respect is the species comprised of the alpha7 gene product (Broide and Leslie, 1999). These alpha7 homopentameric nicotinic acetylcholine receptors (alpha7 nAChRs) have a high relative permeability to calcium, rivaling that of NMDA receptors. But unlike NMDA receptors, alpha7 nAChRs promote calcium influx without requiring a coincident event such as membrane depolarization. As a result, the receptors are well equipped to regulate calcium-dependent events in neurons, particularly when depolarization might be occluded.

Animals↗
PubMed2006

Anaerobic uptake of phosphate in an anaerobic-aerobic granular sludge sequencing batch reactor.

An unusual phenomenon of anaerobic phosphate uptake under alternating anaerobic/aerobic condition was observed in a granular sludge sequencing batch reactor, fed with acetate as sole organic substrate. Anaerobic phosphate uptake efficiencies remained at 50-70% as the influent P/COD was increased from 2/100 to 4/100, and results showed that anaerobic uptake of phosphate was correlated with anaerobic absorption of acetate. Excluding the main possibility of chemical phosphate removal, it appeared that phosphate uptake during the anaerobic phase was associated with organisms enriched in the reactor. Moreover, results indicated that intracellular glycogen was used as the main energy source of organics anaerobic absorption and intracellular polymers storage. Measuring and analysing the variation of phosphate, organic substrate, intracellular glycogen and pH in the anaerobic phase, a preliminary explanation was developed that anaerobic uptake of phosphate was the demand of intracellular glycogen degradation, and extracellular phosphate was transported to intracellular by pH gradient-sensitive phosphate carrier protein.

Aerobiosis↗