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Biomedical subjects

Z Wang

Publications and source records attributed to Z Wang.

At least 109 records · Page 6Linked to original sources
PubMed2004

Quantitative analysis of cells in the ganglion cell layer of the chick retina: developmental changes in cell density and cell size.

Changes in cell density and size in the ganglion cell layer (GCL) of the retina were studied in chick embryos and post-hatching chicks. The total number of cells in the GCL increased from 3.64 million at embryonic day 8 (E8) to the maximal 7.85 million at E14. After E14, the number of cells decreased to 6.08 million at post-hatching day 1 (P1) and 4.87 million at P8. Cell density in the GCL decreased unevenly according to retinal regions; cell density in the presumptive central area (pCA) of P8-chicks decreased to approximately 45% of that in E8-embryos. Densities of the nasal peripheral retina (NP) and temporal peripheral retina (TP) of P8-chicks decreased to 23 and 18% of E8-embryos, respectively. Differentiation of the central (44,000 cells/mm(2) in pCA) - peripheral (28,000 cells/mm(2) in TP) gradient in cell density was formed by E8. The presumptive dorsal area (pDA) was shaped by E11, but became obscure with age. Although ganglion cell sizes were basically uniform at E8, differentiation occurred with the appearance of larger ganglion cells after E14. Mean size of retinal ganglion cells increased 2.8-fold in the pCA and 3.8-fold in the TP between E8 and P8, accompanying a similar scale of decreases in cell densities.

Animals↗
PubMed2004

Distribution and shifting trends of bacterial keratitis in north China (1989-98).

AIMS: To study the distribution and shifting trends of bacterial keratitis. METHODS: The data of 2220 corneal isolates from 1 January 1989 to 31 December 1998 were reviewed retrospectively. RESULTS: Positive culture was recovered in 490 isolates. Gram positive cocci and Gram negative bacilli represented 51% and 39.4%, respectively. Pseudomonas aeruginosa was the most common pathogen (32.2%). A gradual increase in the percentage of Gram positive cocci coupled with a decrease of Gram negative bacilli. CONCLUSION: Pseudomonas aeruginosa and coaculase negative Staphylococcus were the most common pathogens in bacterial keratitis in north China.

China↗
PubMed2004

Effects of high intensity focused ultrasound on vascular endothelial growth factor in melanoma bearing mice.

This study was to investigate the effects of high intensity focused ultrasound on vascular endothelial growth factor. A B16 melanoma model was adopted in our study. Melanoma bearing mice were randomly divided into two groups: HIFU group and surgery group. While the control group was only injected with isovolumetric normal saline solution and treated as the surgery group. We detected VEGF both in tissues and sera through immunohistochemical method and ELISA respectively. Tissues were sampled pre- and at the 3rd day post-operation in HIFU group and blood samples were taken pre- and at the 1st, 3rd, and 7th day post-operation in all the groups. As a result, in the tissues, VEGF was expressed in 80% melanomas, but none was detected in the targeted area after HIFU treatment. In the sera, there was a decreasing tendency of serum-VEGF concentrations in group HIFU and surgery after operation, while that in the control group increased after operation. The levels in the HIFU group on day 1, 3, and 7 postoperatively were all lower than that in the surgery group respectively (79.16 pg/ml vs 91.59 pg/ml; 33.64 pg/ml vs 49.39 pg/ml; 30.37 pg/ml vs 46.68 pg/ml), but there wasn't any significant difference (P > 0.05). So HIFU can destroy VEGF in the targeted area and maybe have less of an effect on serum-VEGF than surgery.

Animals↗
PubMed2004

NO-1886 decreases ectopic lipid deposition and protects pancreatic beta cells in diet-induced diabetic swine.

The synthetic compound NO-1886 (ibrolipim) is a lipoprotein lipase activator that has been proven to be highly effective in lowering plasma triglycerides. Recently, we found that NO-1886 also reduced plasma free fatty acids and glucose in high-fat/high-sucrose diet-induced diabetic rabbits. In the current study, we investigated the effects of NO-1886 treatment on ectopic lipid deposition and the islet pathology in miniature swine fed a high-fat/high-sucrose diet. Our results showed that feeding this diet to miniature swine caused insulin resistance, increased lipid deposition in non-adipose tissue, such as in the heart, skeletal muscle, liver and pancreas, and also caused pancreatic beta cell damage. However, supplementing 1% NO-1886 (200 mg/kg per day) into the high-fat/high-sucrose diet decreased ectopic lipid deposition, improved insulin resistance, and alleviated the beta cell damage. These results suggest that improvement of lipid disorder, non-adipose tissue steatosis and insulin resistance may be very important for the protection of beta cell damage. Therefore, NO-1886 is potentially beneficial for the treatment of insulin-resistance syndrome.

Animals↗
PubMed2004

In vitro fermentation of various fiber and starch sources by pig fecal inocula.

Freeze-dried ileal effluent (1% wt/vol) from cannulated pigs fed rice-based diets with the inclusion of either animal protein (CON), animal protein plus potato starch (PS), animal protein plus sugar beet pulp (SBP), or animal protein plus wheat bran (WB) was incubated anaerobically at pH 6.0 in fermenters containing 5% (wt/vol) fecal slurry comprising mineral salts medium and 50 g/L of fresh feces from pigs fed the same diets as the cannulated pigs. Samples were collected from the fermenters at 0, 2, 4, 12, 24, and 48 h during in vitro fermentation for measuring nonstarch polysaccharides (NSP), starch, and short-chain fatty acids (SCFA). Results showed that the major SCFA produced were acetate, propionate, and butyrate. The inclusion of soluble dietary fiber (diet SBP) caused the highest concentrations of acetate, propionate, butyrate, and total SCFA, whereas the increase in the production of propionate resulting from the addition of insoluble dietary fiber (diet WB) only occurred at the initial stages during 48 h in vitro fermentation. At all sampling occasions (except for 4 h), the levels of butyrate were increased (P < 0.01) by resistant starch compared with fiber sources, showing that a higher level of butyrate can be achieved through microbial fermentation by potato starch. Lowered (P < 0.05) butyrate concentrations were observed with diet WB during in vitro fermentation. With the inclusion of fiber sources, the energy originating from SCFA was similar to that from NSP disappearance, whereas the values were lower (P < 0.05) from NSP disappearance than for SCFA generated without fiber sources supplemented. We conclude that more substrate is available in ileal effluent with the addition of soluble dietary fiber, and an increased level of butyrate could be achieved through microbial fermentation by resistant starch.

Animals↗
PubMed2003

Field fluorometers as dispersed oil-in-water monitors.

A laboratory study of the Turner Instrument flow-through models 10AU and 10 fluorometers was conducted to review their ability to measure real-time oil-in-water concentrations, to compare the results to other total petroleum hydrocarbon (TPH) procedures and to improve the understanding of the relationship of the fluorescence to the chemical composition of the oils. Comparison of the fluorometer results to standard infrared and gas chromatography laboratory procedures showed all methods capable of detecting and differentiating between small changes in oil concentration. The infrared and gas chromatography generated similar values while the fluorometer values were of the same order of magnitude but typically 20-80% higher. The chemical composition of the oils was determined by gas chromatographic techniques and compared to the signal outputs of the fluorometers. It was found that the fluorometer data could not be directly linked to the concentration of any specific aromatic hydrocarbon such as naphthalene or to the sum of the polycyclic aromatic hydrocarbon (PAH) compounds. Evidence suggests that the fluorescence signal is generated by a combination of PAH compounds. Also, the response of the fluorometers may also be influenced by the presence of volatile aromatic compounds such as benzene, toluene, ethyl benzene and xylene (BTEX) and C3-benzenes (BTEX + C3B) in combination with the PAH compounds.

Chromatography, Gas↗
PubMed2003

EGF stimulates growth by enhancing capacitative calcium entry in corneal epithelial cells.

In rabbit corneal epithelial cells (RCEC), we determined whether capacitative calcium entry (CCE) mediates the mitogenic response to epidermal growth factor, EGF. [Ca2+]i was measured with single-cell fluorescence imaging of fura2-loaded RCEC. EGF (5 ng/ml) maximally increased [Ca2+]i 4.4-fold. Following intracellular store (ICS) calcium depletion in calcium-free medium with 10 microM cyclopiazonic acid (CPA) (endoplasmic reticulum calcium ATPase inhibitor), calcium addback elicited plasma membrane Ca2+ influx as a result of activation of plasma membrane store operated channel (SOC) activity. Based on Mn2+ quench measurements of fura2 fluorescence, 5 ng/ml EGF enhanced such influx 2.3-fold, whereas with Rp-cAMPS (protein kinase A inhibitor) plus EGF it increased by 5.3-fold. In contrast, SOC activation was blocked with 100 microM 2-aminoethyldiphenylborate (2-APB, store-operated channel inhibitor). During exposure to either 50 microM UO126 (MEK-1/2 inhibitor) or 10 microM forskolin (adenylate cyclase activator), 5 ng/ml EGF failed to affect [Ca2+]i. RT-PCR detected gene expression of: 1) transient receptor potential (TRP) protein isoforms 1, 3, 4, 6 and 7; 2) IP3R isoforms 1-3. Immunocytochemistry, in conjunction with confocal and immunogold electron microscopy, detected plasma membrane localization of TRP4 expression. Inhibition of CCE with 2-APB and/or CPA, eliminated the 2.5-fold increase in intracellular [3H]-thymidine incorporation induced by EGF. Taken together, CCE in RCEC mediates the mitogenic response to EGF. EGF induces CCE through its stimulation of Erkl/2 activity, whereas PKA stimulation suppresses these effects of EGF. TRP4 may be a component of plasma membrane SOC activity, which is stimulated by ICS calcium depletion.

Animals↗
PubMed2003

Hypertonicity-induced p38MAPK activation elicits recovery of corneal epithelial cell volume and layer integrity.

In hypertonicity-stressed (i.e., 600 mOsm) SV40-immortalized rabbit and human corneal epithelial cell layers (RCEC and HCEC, respectively), we characterized the relationship between time-dependent changes in translayer resistance, relative cell volume and modulation of MAPK superfamily activities. Sulforhodamine B permeability initially increased by 1.4- and 2-fold in RCEC and HCEC, respectively. Subsequently, recovery to its isotonic level only occurred in RCEC. Light scattering revealed that in RCEC 1) regulatory volume increase (RVI) extent was 20% greater; 2) RVI half-time was 2.5-fold shorter. However, inhibition of Na-K-2Cl cotransporter and Na/K-ATPase activity suppressed the RVI response more in HCEC. MAPK activity changes were as follows: 1) p38 was wave-like and faster as well as larger in RCEC than in HCEC (90- and 18-fold, respectively); 2) increases in SAPK/JNK activity were negligible in comparison to those of p38; 3) Erk1/2 activity declined to 30-40% of their basal values. SB203580, a specific p38 inhibitor, dose dependently suppressed the RVI responses in both cell lines. However, neither U0126, which inhibits MEK, the kinase upstream of Erk, nor SP600125, inhibitor of SAPK/JNK, had any effect on this response. Taken together, sufficient activation of the p38 limb of the MAPK superfamily during a hypertonic challenge is essential for maintaining epithelial cell volume and translayer resistance. On the other hand, Erk1/2 activity restoration seems to be dependent on cell volume recovery.

Adaptation, Physiological↗
PubMed2003

A constrained variational principle for direct estimation and smoothing of the diffusion tensor field from DWI.

In this paper, we present a novel constrained variational principle for simultaneous smoothing and estimation of the diffusion tensor field from diffusion weighted imaging (DWI). The constrained variational principle involves the minimization of a regularization term in an LP norm, subject to a nonlinear inequality constraint on the data. The data term we employ is the original Stejskal-Tanner equation instead of the linearized version usually employed in literature. The original nonlinear form leads to a more accurate (when compared to the linearized form) estimated tensor field. The inequality constraint requires that the nonlinear least squares data term be bounded from above by a possibly known tolerance factor. Finally, in order to accommodate the positive definite constraint on the diffusion tensor, it is expressed in terms of cholesky factors and estimated. variational principle is solved using the augmented Lagrangian technique in conjunction with the limited memory quasi-Newton method. Both synthetic and real data experiments are shown to depict the performance of the tensor field estimation algorithm. Fiber tracts in a rat brain are then mapped using a particle system based visualization technique.

Algorithms↗
PubMed2003

Measurement of intramyocellular lipid levels with 2-D magnetic resonance spectroscopic imaging at 1.5 T.

Intramyocellular lipid (IMCL) plays an important role in the study of metabolism in vivo. Magnetic resonance spectroscopy (MRS) studies of IMCL are usually performed with clinical 1.5-T magnetic resonance imaging (MRI) systems and have employed the single-voxel MRS technique. The present study reports the results of our systematic evaluation of the ability of single- and multi-voxel MRS to yield high-quality, contamination-free IMCL levels from the tibialis anterior (TA) muscle. A clinical, 1.5-T, whole-body MRI scanner was used to measure IMCL with a standard knee coil, head coil, or a 3-cm receive-only surface coil with a body coil transmit. Excellent IMCL spectra were obtained in healthy males in only 8 min from multiple 0.25-cm(3) voxels using the surface coil receive/body coil transmit in conjunction with the standard PRESS spectroscopic imaging (SI) technique. This approach provided the spatial resolution and voxel placement flexibility permitting optimal separation of IMCL and extramyocellular lipid. Our findings demonstrate the potential of the SI approach.

Humans↗
PubMed2003

Differential effects of intraspecific interactions on the striatal dopamine system in social and non-social voles.

We used in vivo microdialysis to examine the responses to intraspecific social interactions in the striatal dopamine systems of females of two vole species displaying vastly different social structures. Both highly social prairie voles and asocial meadow voles had similar increases in extracellular dopamine associated with mating. There was a species-specific effect of social condition on extracellular dihydroxyphenylacetic acid (DOPAC). Exposure to a conspecific male significantly decreased extracellular DOPAC in female prairie voles isolated for approximately 18 h during surgical recovery. Such decrease in DOPAC was not seen if females experienced continued isolation or if they were housed with a sibling during surgical recovery. No changes in extracellular DOPAC were seen in meadow voles after manipulations of social environment. Together, our data indicate that mating-associated dopamine release is independent from mating systems. However, species-specific patterns of extracellular DOPAC suggest that social isolation may be a more stressful stimulus for the social prairie vole than for the asocial meadow vole.

3,4-Dihydroxyphenylacetic Acid↗
PubMed2003

Case-control study of the association between kava use and pneumonia in eastern Arnhem and Aboriginal communities (Northern Territory, Australia).

Pneumonia causes significant morbidity and mortality in Aboriginal populations in Australia's Northern Territory (NT). Kava, consumed in Arnhem Land since 1982, may be a risk factor for infectious disease including pneumonia. A case-control study (n = 115 cases; n = 415 controls) was conducted in 7001 Aboriginal people (4217 over 15 years). Odds ratios (OR) were calculated by conditional logistic regression with substance use and social factors as confounders. Pneumonia was not associated with kava use. Crude OR = 1.26 (0.74-2.14, P = 0.386), increased after controlling for confounders (OR = 1.98, 0.63-6.23, P = 0.237) but was not significant. Adjusted OR for pneumonia cases involving kava and alcohol users was 1.19 (0.39-3.62, P = 0.756). In communities with longer kava-using histories, adjusted OR was 2.19 (0.67-7.14, P = 0.187). There was no kava dose-response relationship. Crude ORs for associations between pneumonia and cannabis use (OR = 2.27, 1 18-4.37, P = 0.014) and alcohol use (OR = 1.95, 1.07-3.53, P = 0.026) were statistically significant and approached significance for petrol sniffing (OR = 1.98, 0.99-3.95, P = 0.056).

Adult↗
PubMed2003

Sequence-based discovery of a synthetic peptide inhibitor of caspase 6.

We recently demonstrated that tumor necrosis factor alpha activates caspase 6, which in turn cleaves transcription factor AP-2 alpha. We mapped the cleavage site at 19 amino acids from the N-terminus at the sequence aspartate-argenine-histidine-aspartate (DRHD). Mutating aspartic acid at position 19 abrogated the cleavage site. From these observations, we hypothesized that the DRHD peptide could act as a caspase 6 inhibitor. To test this hypothesis, the peptide zAsp(Ome)-Arg-His-Asp(Ome)-fluoromethyl ketone (zDRHDfmk) was synthesized. Here we show that zDRHDfmk inhibits TNFalpha-induced caspase 6 activity and apoptosis in breast cancer cells. When compared to other caspase inhibitors, zDRHDfmk inhibited caspase 6 activity more effectively than the general caspase inhibitor zVal-Ala-Lys(Ome)-fluoromethy ketone (zVADfmk) or the caspase 6 inhibitor zVal-Glu-Ile-Asp-(Ome)-fluoromethyl ketone (zVEIDfmk). However, it was less effective in inhibiting TNFalpha-induced apoptosis than zVADfmk or zVEIDfmk, presumably because caspase 6 is only one of at least three effector caspases, the others being caspase 3 and 7, that are active during caspase-dependent apoptosis. The discovery of this sequence-based caspase 6 inhibitor provides a new tool for studying caspase 6. More importantly, it could be used, in combination with other agents, as a drug to inhibit apoptosis in neurodegenrative diseases such as Alzheimer's, Parkinson and amyotrophic lateral sclerosis.

Adaptor Protein Complex 2↗
PubMed2003

Dendritic cells genetically engineered to express IL-4 exhibit enhanced IL-12p70 production in response to CD40 ligation and accelerate organ allograft rejection.

C57BL/10 (B10; H2(b)) bone marrow-derived myeloid dendritic cells (DC) propagated in GM-CSF + IL-4 were transduced with r adenoviral (Ad) vectors encoding either control neomycin-resistance gene (Ad-Neo) or murine IL-4 (Ad-IL-4) on day 5 of culture following CD11c immunomagnetic bead purification. Both Ad-Neo- and Ad-IL-4-transduced DC displayed upregulated surface MHC class II and costimulatory molecules (CD40, CD80, CD86). Ad-IL-4 DC secreted higher levels of bioactive IL-12p70 after CD40 ligation or LPS stimulation than either Ad-Neo or unmodified DC. Only Ad-IL-4 DC produced IL-12p70 in primary MLR, in which they induced augmented proliferative responses of naïve allogeneic C3H/HeJ (C3H; H2(k)) T-cells. Compared with Ad-Neo DC, Ad-IL-4 DC were also more effective in priming naïve allogeneic recipients to exhibit specifically enhanced anti-donor T-cell proliferative and CTL responses. T-cells primed in vivo 7 days previously with Ad-IL-4 DC displayed enhanced secretion of Th2 (IL-4, IL-10) but also higher Th1 cytokine (IFNgamma) production following ex vivo challenge with donor alloAg. Moreover, pretreatment of vascularized heart graft recipients with i.v. Ad-IL-4 DC, 1 week before transplant, significantly accelerated rejection and antagonized the therapeutic effect of anti-CD40L (CD154) mAb. These data contrast markedly with recently reported inhibitory effects of autologous Ad-IL-4 DC on autoimmune inflammatory disease.

Animals↗
PubMed2003

Rapid and highly efficient transduction by double-stranded adeno-associated virus vectors in vitro and in vivo.

Adeno-associated virus (AAV) is a promising gene vector based on a single-stranded (ss) DNA virus. Its transgene expression requires the conversion of ssDNA to double-stranded (ds) genome, a slow process responsible for the delayed transduction and occasional inefficiency. By mutating the inverted terminal repeat, we have made novel AAV vectors that predominantly package the self-complementary dsDNA genome. The dsAAV consistently demonstrated superior and accelerated transduction in vitro and in vivo. Dramatic increases in transgene expression were observed in most of the cell lines examined, including B16 melanoma and 3LL lung cancer that are difficult to be transduced by the conventional ssAAV vectors. Similar increases were also observed in vivo in a variety of tissues including muscle and liver. The dsAAV transduced a vast majority of the hepatocytes for more than 6 months, while the ssAAV transduced only a small fraction. In addition to circumventing the requirement for DNA synthesis, the dsAAV exhibited higher in vivo DNA stability and more effective circularization than the ssAAV, suggesting potential molecular mechanisms for the faster, stronger and prolonged transgene expression.

Animals↗