Biomedical subjects
Publications and source records attributed to Hui Huang.
We use direct-write laser micromachining technology to fabricate the microfluidic chip, and to establish a microfluidic chemiluminescence immunoassay system based on superparamagnetic microbeads, for detecting alpha- fetoprotein (AFP). The AFP analysis can be completed in 20 minutes with 5 microl sample and 5 microl reagent, and there is a good linear correlation in the range of 1-800 ng/ml.
Human platelet alloantigens (HPA) are specific antigens carried by platelet glycoproteins, which genes showing single nucleotide polymorphism. HPA can induce alloantibodies bringing about alloimmune response. They play important roles in post-transfusion refractoriness to platelets, post-transfusion thrombocytopenic purpura, fetomaternal alloimmune thrombocytopenia, and graft-versus-host disease. Because of their side effects in clinical blood-transfusion, there were a great deal of studies on HPA during last few decades. This review focuses on the nomenclature of HPA, the polymorphisms of platelet glycoproteins, HPA typing of the serological and molecular technology, as well as the mechanism of alloimmunization to HPA and correlated diseases.
This study compared renal hemodynamics, the expression of CYP4A isoforms [the enzymes for 20-hydroxyeicosatetraenoic acid (20-HETE) production], and tubular sodium transporters in male rats fed a high-fat (HF) or control diet for 10 weeks. We also studied the effect of treatment with clofibrate, a CYP4A inducer, on sodium retention and renal function and on CYP4A expression in HF rats. HF rats had higher blood pressure (BP), renal plasma flow, and glomerular filtration rate (GFR), but no significant change in renal vascular resistance. Reverse transcription-polymerase chain reaction analysis showed that CYP4A1 and CYP4A8 expression was significantly decreased in the renal cortex of HF rats. Western blot analysis showed up-regulation of expression of the alpha-subunit of the epithelial sodium channel (alpha-ENaC), the beta-subunit of the epithelial sodium channel (beta-ENaC), sodium/hydrogen exchanger (NHE)-3, and the renal outer medulla K(+) channel (ROMK) in HF rats, whereas expression of the gamma-subunit of the epithelial sodium channel and the alpha1-subunit of Na(+)-K(+)-ATPase remained unchanged. Thus, HF treatment caused the reduction of renal CYP4A1 and CYP4A8 expression, whereas the increases in alpha-ENaC, beta-ENaC, NHE-3, and ROMK expression in renal tubules may have contributed sodium retention and hypertension in HF rats. Furthermore, clofibrate treatment (240 mg/kg/day) caused the decrease of BP and GFR and the attenuation of cumulative sodium balance in HF rats. The attenuation of sodium retention by clofibrate treatment is linked to decreased expression of NHE-3 in renal cortex. Clofibrate induction of CYP4A expression occurred in proximal tubules and in the thick ascending limb of the loop of Henle but not in renal microvessels. This induction correlated with the expression of peroxisome proliferator-activated receptor (PPARalpha) in renal tubules. Therefore, these results suggest that the effects of clofibrate on sodium retention and blood pressure regulation in HF rats may be due to the induction of renal tubular 20-HETE production through the PPARalpha pathway.
A series of L-nitroarginine-based dipeptide inhibitors are highly selective for neuronal nitric oxide synthase (nNOS) over the endothelial isoform (eNOS). Crystal structures of these dipeptides bound to both isoforms revealed two different conformations, curled in nNOS and extended in eNOS, corresponding to higher and lower binding affinity to the two isoforms, respectively. In previous studies we found that the primary reason for selectivity is that Asp597 in nNOS, which is Asn368 in eNOS, provides greater electrostatic stabilization in the inhibitor complex. While this is the case for smaller dipeptide inhibitors, electrostatic stabilization may no longer be the sole determinant for isoform selectivity with bulkier dipeptide inhibitors. Another residue farther away from the active site, Met336 in nNOS (Val106 in eNOS), is in contact with bulkier dipeptide inhibitors. Double mutants were made to exchange the D597/M336 pair in nNOS with N368/V106 in eNOS. Here we report crystal structures and inhibition constants for bulkier dipeptide inhibitors bound to nNOS and eNOS that illustrate the important role played by residues near the entry to the active site in isoform selective inhibition.
This paper reports the synthesis, fluorescence properties, and biological applications of naphthofluorescein disulfonate (NFDS-1), as a red fluorescence imaging probe to detect intracellular H2O2.
It is clear that dendritic cells (DCs) are essential for priming of T cell responses against tumors. However, the distinct roles DC subsets play in regulation of T cell responses in vivo are largely undefined. In this study, we investigated the capacity of OVA-presenting CD4-8-, CD4+8-, or CD4-8+ DCs (OVA-pulsed DC (DC(OVA))) in stimulation of OVA-specific T cell responses. Our data show that each DC subset stimulated proliferation of allogeneic and autologous OVA-specific CD4+ and CD8+ T cells in vitro, but that the CD4-8- DCs did so only weakly. Both CD4+8- and CD4-8+ DC(OVA) induced strong tumor-specific CD4+ Th1 responses and fully protective CD8+ CTL-mediated antitumor immunity, whereas CD4-8- DC(OVA), which were less mature and secreted substantial TGF-beta upon coculture with TCR-transgenic OT II CD4+ T cells, induced the development of IL-10-secreting CD4+ T regulatory 1 (Tr1) cells. Transfer of these Tr1 cells, but not T cells from cocultures of CD4-8- DC(OVA) and IL-10-/- OT II CD4+ T cells, into CD4-8+ DC(OVA)-immunized animals abrogated otherwise inevitable development of antitumor immunity. Taken together, CD4-8- DCs stimulate development of IL-10-secreting CD4+ Tr1 cells that mediated immune suppression, whereas both CD4+8- and CD4-8+ DCs effectively primed animals for protective CD8+ CTL-mediated antitumor immunity.
We previously reported that inhibition of nitric oxide (NO) synthesis by N-nitro-L-arginine methyl ester (L-NAME) during late pregnancy leads to increased production of renal vascular 20-hydroxyeicosatetraenoic acid (20-HETE), a cytochrome P-450 (CYP) 4A-derived vasoconstrictor, in pregnant rats. However, the effect of upregulation of vascular 20-HETE production on renal function after NO inhibition is not known. To test the hypothesis that increased gestational vascular 20-HETE synthesis after NO inhibition is involved in mediating blood pressure and renal functional changes, we first determined the IC(50) value of the effect of nitroprusside (SNP), a NO donor, on renal 20-HETE production in cortical microsomes. We then divided pregnant rats and age-matched virgin rats into a vehicle control group, an L-NAME treatment group (0.25 mg/ml in drinking water), and a group treated with L-NAME plus N-methylsulfonyl-12,12-dibromododec-11-enamide (DDMS; CYP4A-selective inhibitor, 10 mg.kg(-1).day(-1) iv). After 4 days of treatment, we measured blood pressure, renal blood flow (RBF), renal vascular resistance (RVR), and glomerular filtration rate (GFR) in each group. The addition of SNP (IC(50) = 22 microM) decreased renal cortical 20-HETE production. In pregnant rats, L-NAME treatment led to significantly higher mean arterial pressure (MAP) and RVR, and lower RBF and GFR. Combined treatment with DDMS and L-NAME significantly attenuated the increases in MAP and RVR and the decrease in GFR, but not the reduction in RBF induced by L-NAME treatment. L-NAME and L-NAME plus DDMS had no significant impact on renal hemodynamics in virgin rats. In addition, chronic treatment with DDMS selectively inhibited cortical 20-HETE production without a significant effect on CYP4A expression in L-NAME-treated pregnant rats. In conclusion, NO effectively inhibits renal cortical microsomal 20-HETE production in female rats. In pregnant rats, the augmentation of renal 20-HETE production after NO inhibition is associated with increased MAP and RVR, whereas decreased GFR is negated by treatment of a selective and competitive CYP4A inhibitor. These results demonstrate that the interaction between renal 20-HETE and NO is important in the regulation of renal function and blood pressure in pregnant rats.
Phycobilisomes are protein complexes that harvest light and transfer energy to the photo system. Here, the three dimensional structure of intact phycobilisomes from Nostoc flagelliforme is studied by a combination of negative stain electron microscopy and cryo-electron microscopy. Results show that the intact phycobilisomes are composed of a tricylindrical core and six rods. Each allophycocyanin cylinder presents a double-layered structure when viewed from the side and a triangular shape when viewed from the top. These characteristics indicate that allophycocyanin trimers in the intact phycobilisomes are arranged into hexameric oligomers in a parallel manner.
Cyclin-dependent kinase inhibitors (CKIs) and Notch receptor activation have been shown to influence adult stem cells and progenitors by altering stem cell self-renewal and proliferation. Yet, no interaction between these molecular pathways has been defined. Here we show that ligand-independent and ligand-dependent activation of Notch1 induces transcription of the S phase kinase-associated protein 2 (SKP2), the F-box subunit of the ubiquitin-ligase complex SCF(SKP2) that targets proteins for degradation. Up-regulation of SKP2 by Notch signaling enhances proteasome-mediated degradation of the CKIs, p27 Kip1 and p21 Cip1, and causes premature entry into S phase. Silencing of SKP2 by RNA interference in G1 stabilizes p27 Kip1 and p21 Cip1 and abolishes Notch effect on G1-S progression. Thus, SKP2 serves to link Notch1 activation with the cell cycle machinery. This novel pathway involving Notch/SKP2/CKIs connects a cell surface receptor with proximate mediators of cell cycle activity, and suggests a mechanism by which a known physiologic mediator of cell fate determination interfaces with cell cycle control.
A long-standing paradox in cellular immunology has been the conditional requirement for CD4(+) Th cells in priming of CD8(+) CTL responses. We propose a new dynamic model of CD4(+) Th cells in priming of Th-dependent CD8(+) CTL responses. We demonstrate that OT II CD4(+) T cells activated by OVA-pulsed dendritic cells (DC(OVA)) are Th1 phenotype. They acquire the immune synapse-composed MHC II/OVAII peptide complexes and costimulatory molecules (CD54 and CD80) as well as the bystander MHC class I/OVAI peptide complexes from the DC(OVA) by DC(OVA) stimulation and thus also the potential to act themselves as APCs. These CD4(+) Th-APCs stimulate naive OT I CD8(+) T cell proliferation through signal 1 (MHC I/OVAI/TCR) and signal 2 (e.g., CD54/LFA-1 and CD80/CD28) interactions and IL-2 help. In vivo, they stimulate CD8(+) T cell proliferation and differentiation into CTLs and induce effective OVA-specific antitumor immunity. Taken together, this study demonstrates that CD4(+) Th cells carrying acquired DC Ag-presenting machinery can, by themselves, efficiently stimulate CTL responses. These results have substantial implications for research in antitumor and other aspects of immunity.
A [3 + 3] modular self-assembly gives rise to the formation of basket-shaped, crown ether-functionalized, nano-sized trimetallo-macrocycles, which function as structural analogues of cyclotriveratrylenes (CTV).
In this paper, we report the use of binary carbon supports (carbon nanotubes (CNTs) and active carbon) as a catalyst layer for fabricating gas diffusion electrodes. The electrocatalytic properties for the oxygen reduction reaction (ORR) were evaluated by polarization curves and electrochemical impedance spectroscopy (EIS) in an alkaline electrolyte. The binary-support electrode exhibits better performance than the single-support electrode, and the best performance is obtained when the mass ratio of carbon nanotubes and active carbon is 50:50. The results from the electrode kinetic parameters indicate that the introduction of carbon nanotubes as a secondary support provides high accessible surface area, good electronic conductivity, and fast ORR kinetics. Furthermore, the effect of CNT support on the electrocatalytic properties of Pt nanoparticles for binary-support electrodes was also investigated by different loading-reduction methods. The electrocatalytic activity of the binary-support electrodes is improved dramatically by Pt loading on CNT carbon support, even at very low Pt loading. Additionally, the EIS analysis results indicate that the process of ORR may be controlled by diffusion of oxygen in the electrode thin film for binary-support electrodes with or without Pt catalyst.
OBJECTIVE: To explore the role of the neuropeptide in fetal scarless wound healing. METHODS: The animal models were replicated in which a full-thickness wound was inflicted on the back of rabbit fetuses at 22 days gestation (term=31 days). The progress of wound healing was observed on micro-and macro-levels at the 1 st, 2 nd, 3 rd, 5 th, 7 th, 14 th post-injury days respectively. The expression level of substance P(SP) and calcitonin gene-related peptide (CGRP) during wound healing was assessed by immunohistochemistry staining. RESULTS: The cutaneous wounds in fetal rabbits healed more rapidly than that in adult and without the formation of scar. The expression of SP and CGRP of wound decreased in fetal rabbit at the early stage post-injury, down to the lowest levels on the 2 nd post-injury day (75%, 80%, vs. fetal control, both P<0.01), then increased gradually, up to the normal levels. The expression of SP and CGRP of wound decreased in adult rabbit at the early stage post-injury, down to the lowest levels on the post-injury 1 st day (60%, 76%, vs. adult control, both P<0.01), then increased quickly, up to a higher level than normal group, reaching the peak on the post-injury 7th day(168%, 126%, vs. adult control, both P<0.01), then returned to the normal levels. CONCLUSION: The low level of neuropeptide may contribute to scarless wound healing in fetal rabbit.
BACKGROUND & OBJECTIVE: Dendritic cells (DCs) can activate immunologic naive T cells to initiate antigen-specific immune responses. This study was to in vitro induce mature DCs from malignant pleural effusions of patients with lung cancer. METHODS: Malignant pleural effusions (500-1 000 ml) were collected from 16 patients with primary lung cancer. Precursory DCs were obtained through density gradient centrifugation and magnetic cell sorting from malignant pleural effusions, and cultured with interleukin-4 (IL-4), granulocyte-macrophage colony-stimulating factor (GM-CSF), and tumor necrosis factor-alpha (TNF-alpha). Morphology of DCs was observed under invert optical microscope and electronic microscope; phenotype of DCs was analyzed by flow cytometry. Effect of DCs on proliferation of tumor infiltrative lymphocytes (TILs) was observed through mixed lymphocyte reaction (MLR). RESULTS: Mature DCs with typical morphology (elongated dendritic processions observed under invert optical microscope and electronic microscope) were induced from malignant pleural effusions. Expressions of surface phenotypes were higher in DCs induced for 48 h than in DCs induced for 0, 24, 96, and 192 h. When activated with DCs, proliferation of TILs was enhanced. CONCLUSION: Mature DCs could be induced from malignant pleural effusions of patients with lung cancer.
This study sought to assess the effects of Quercetin and Enalapril on urinary protein excretion and amount of platelet-derived growth factor-B (PDGF-B) and vascular endothelial growth factor-1 (VEGF-1) in renal tissue of diabetic rats. 29 streptozotocin-induced diabetic rats were divided into 3 groups, diabetic control group (group D, n=12); Enalapril group (group E, n=10); Quercetin group (group Q, n=7). In addition, there was one normal control group (group N, n = 5). The urinary protein excretion of 24 hours was measured at 4, 8, 12 weeks. All rats were sacrificed at 12 weeks. The amounts of PDGF-B and VEGF-1 in renal tissue were measured by immunohistochemical techniques. The 24-h levels of urinary protein excretion of D,Q and E groups were higher than that of N group; the level of Q, E groups were lower than that of D group; there was no difference between Q and E group. The expression levels of PDGF-B and VEGF-1 in renal tissue of D, Q, and E groups were significantly higher than that of N group the levels of Q and E groups were significantly lower than that of D group, no difference was found between Q and E group. The protective role of Quercetin and Enalapril in lowering urinary protein excretion may be related to the decreased amounts of PDGF-B and VEGF-1 in renal tissue.
The micro-photoluminescence of five cadmium zinc telluride crystal wafers was measured by laser excited micro-Raman spectroscopy. The Eg value of cadmium zinc telluride material was calculated by fitting the micro-photoluminescence peaks which came from material band gap. Then the Zn composition of cadmium zinc telluride material could be obtained. By using the spectroscopic function of X-Y scanning technique fixing the photoluminescence peak, the mapping of Zn composition could be easily and non-destructively given.
OBJECTIVE: To investigate the diagnostic value of magnetic resonance imaging (MRI) for lower limb osteosarcoma by comparing the findings between X-ray and MRI. METHODS: Fifteen surgically or pathologically confirmed patients with lower limb osteosarcoma (11 males and 4 females) underwent both plain and enhanced MRI (with CT scanning in 4 cases) in addition to radiography, and the findings were compared. RESULTS: The diagnostic accuracy of both MRI and X-ray film was 100%. Compared with X-ray, MRI was capable of clear display of the lesion extent, perpendicular periosteal reaction, the two layers of Codman's triangle and the skip lesions. CONCLUSION: Plain X-ray film provides a convenient and practical diagnostic modality for lower limb osteosarcoma, but MRI has better performance in clearer display of the tumor range and identification of early-stage lesions.
BACKGROUND: Analysis of DNA microarray data usually begins with a normalization step where intensities of different arrays are adjusted to the same scale so that the intensity levels from different arrays can be compared with one other. Both simple total array intensity-based as well as more complex "local intensity level" dependent normalization methods have been developed, some of which are widely used. Much less developed methods for microarray data analysis include those that bypass the normalization step and therefore yield results that are not confounded by potential normalization errors. RESULTS: Instead of focusing on the raw intensity levels, we developed a new method for microarray data analysis that maps each gene's expression intensity level to a high dimensional space of SEDs (Signs of Expression Difference), the signs of the expression intensity difference between a given gene and every other gene on the array. Since SED are unchanged under any monotonic transformation of intensity levels, the SED based method is normalization free. When tested on a multi-class tumor classification problem, simple Naive Bayes and Nearest Neighbor methods using the SED approach gave results comparable with normalized intensity-based algorithms. Furthermore, a high percentage of classifiers based on a single gene's SED gave good classification results, suggesting that SED does capture essential information from the intensity levels. CONCLUSION: The results of testing this new method on multi-class tumor classification problems suggests that the SED-based, normalization-free method of microarray data analysis is feasible and promising.