Biomedical subjects
Z Gao
Publications and source records attributed to Z Gao.
Prolonged skin allograft survival in Scid mice reconstituted with isogeneic bone marrow stem cell antigen-1-positive cells and thymus tissue.
INTRODUCTION: Many studies indicate that tolerance induction is much more dependent on the maturation status of lymphocytes than the age of the animal. We hypothesized that direct persistent contact of bone marrow stem cells with graft alloantigen will result in tolerance to that antigen in the adult animal. MATERIAL AND METHODS: Severe combined immunodeficient mice (CB-17-Scid, H-2b) were reconstituted with isogeneic bone marrow stem cell antigen-1 (Sca-1)-positive cells and grafted with fetal thymus (BMSC-T), followed by transplant of allogeneic skin grafts from C57BL/6 (H-2d) mice. The control group include CB-17 non-Scid mice, CB-17-Scid mice, and CB-17 Scid mice pretransplanted with nonmodified isogeneic bone marrow cells and fetal thymus (BMC-T). RESULTS AND DISCUSSION: Skin allograft survival was significantly prolonged in the group pretransplanted with isogeneic BMSC-T compared the group of non-Scid mice and the group of Scid mice pretransplanted with BMC-T (59.6 days vs 7.1 days vs 11.7 days). In 2 of 10 mice pretransplanted with BMSC-T, the skin allografts transplanted immediately after BMSC-T survived for more than 100 days, but the third-party skin allografts transplanted at 100 days after BMSC-T transplant were rejected. The results suggest direct persistent contact of bone marrow Sca-1-positive cells with graft alloantigen may be a feasible approach to prolong allograft survival and induce tolerance in a small fraction of adult animals.
Papillary squamotransitional cell carcinoma of the vagina: a case report and review of literature.
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Identification of markers tightly linked to sbm recessive genes for resistance to Pea seed-borne mosaic virus.
Two virus resistance loci on linkage groups II and VI have provided the only sources of natural resistance against Pea seed-borne mosaic virus (PSbMV, Potyviridae) in the important crop plant Pisum sativum L. A combination of parallel approaches was used to collate linked markers, particularly for sbm-1 resistance on linkage group VI. We have identified sequences derived from the genes for the eukaryotic translation initiation factors eIF4E and eIF(iso)4E as being very tightly linked to the resistance gene clusters on linkage groups VI and II, respectively. In particular, no recombinants between sbm-1 and eIF4E were found amongst 500 individuals of an F2 cross between the BC4 resistant line (JI1405) and its recurrent susceptible parent 'Scout'. In a different mapping population, the gene eIF(iso)4E was also shown to be linked to sbm-2 on linkage group II. A parallel cDNA-AFLP comparison of pairs of resistant and susceptible lines also identified an expressed tag marker just 0.7 cM from sbm-1. eIF4E and eIF(iso)4E have been associated with resistance to related viruses in other hosts. This correlation strengthens the use of our markers as valuable tools to assist in breeding multiple virus resistances into peas, and identifies potential targets for resistance gene identification in pea.
Ultrasound-triggered drug targeting of tumors in vitro and in vivo.
The new modality of drug targeting of tumors that we are currently developing is based on drug encapsulation in polymeric micelles, followed by the localized release at the tumor site triggered by focused ultrasound. The rationale behind this approach is that drug encapsulation in micelles decreases systemic concentration of drug, diminishes intracellular drug uptake by normal cells, and provides passive drug targeting of tumors, thus reducing unwanted drug interactions with healthy tissues. Ultrasound irradiation is used to release drug from micelles at the tumor site and to enhance the intracellular drug uptake by tumor cells. An important advantage of ultrasound is that it is noninvasive, can penetrate deep into the interior of the body, can be focused and carefully controlled. Here we describe factors involved in the ultrasound interaction with viable cells in the absence and presence of drug carriers and anti-cancer drugs. We present in vivo effects of 1 MHz ultrasound on drug biodistribution, intratumoral distribution, and survival rates of immuno-compromised athymic nu/nu mice bearing ovarian carcinoma tumors.
Perivascular epithelioid cell tumour (PEComa) of the uterus associated with malignant neoplasm of the female genital tract.
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Response of Schwann cells in the inferior alveolar nerve to distraction osteogenesis: an ultrastructural and immunohistochemical study.
The biological mechanisms of nerve adaptation to distraction osteogenesis have not yet been elucidated. This study observed response of Schwann cells in the inferior alveolar nerve (IAN) following mandibular lengthening by electron microscopy and immunohistochemistry of S-100 protein, a specific marker of Schwann cells. Unilateral mandibular distraction (10mm elongation) was performed in nine young adult goats. Three animals were sacrificed at 7, 14 and 28 days after completion of distraction, respectively. The distracted IAN specimens and control nerves (from the contralateral sides) were harvested and processed for histological, ultrastructural and immunohistochemical examinations. Wallerian degeneration was observed in the distracted IAN, and Signs of axonal regeneration, as well as many activated Schwann cells were seen in the lengthened nerves. The expression of S-100 protein increased significantly at early stage of distraction osteogenesis, but almost returned to the normal level at 28 days after distraction. This study suggests that Wallerian degeneration caused by mechanical stretching may stimulate Schwann cells to enter a proliferated and activated state. Schwann cells and S-100 protein appear to play crucial roles in axonal regeneration that contributes to nerve adaptation to gradual distraction. Therefore, the IAN injury caused by mandibular gradual distraction was not serious; it seems to recover totally through a complicated repair mechanism.
PEG-PE/phosphatidylcholine mixed immunomicelles specifically deliver encapsulated taxol to tumor cells of different origin and promote their efficient killing.
Mixed micelles were prepared from poly(ethyleneglycol)-distearyl phosphoethanolamine (PEG2000-PE) and egg phosphatidylcholine. The micelles were covalently modified with the nucleosome-specific monoclonal antibody 2C5 known to recognize and bind a variety of tumor cells via their surface-bound nucleosomes. Covalent attachment of 2C5 antibody was performed via a micelle-incorporated PEG-PE with the distal terminus of the PEG block activated with p-nitrophenylcarbonyl group (pNP-PEG-PE). Micelle surface-attached 2C5 antibody maintained its specific activity. 2C5-targeted immunomicelles were able to carry more than 3 wt% of taxol. Taxol-loaded immunomicelles specifically recognized tumor cell lines of several types. The cytotoxicity of 2C5-targeted taxol-loaded immunomicelles in a cell culture model was much higher when compared with free taxol or taxol in non-targeted micelles.
Quantitative diagnosis of fatty liver with dual-energy CT. An experimental study in rabbits.
OBJECTIVES: To explore the correlation between fatty content of fatty liver and the difference of CT attenuation value in dual-energy CT, and to evaluate the value of dual-energy CT in the quantitative diagnosis of fatty liver in rabbits. MATERIAL AND METHODS: Dual-energy CT at 120 kVp and 90 kVp was performed in 16 rabbits of experimental groups that were induced to various degrees of fatty liver by feeding carbon tetrachloride (CCl4). Four healthy rabbits in the control group underwent dual-energy CT at the same time. The CT attenuation values of liver tissues at 120 kVp (H120), 90 kVp (H90) and the difference (Delta H) between them were obtained. The specimens of liver tissues were examined with freeze section (9 microm) and an oil red O stain histologically. The ratio of fatty content in liver to the liver volume (VP value) was measured using the image analyzer system. RESULTS: The change of CT attenuation values between 120 kVp and 90 kVp was not obvious (Delta H between -0.4 HU and 1.4 HU) in the control group. The density of the liver in the experimental groups decreased differently, and the change in CT attenuation values between high and low energy levels were very clear. H120 values were between 51.0 HU and 91.7 HU and H90 values were between 37.0 HU and 89.2 HU. Delta H values were between 2.5 HU and 14.0 HU. Significant negative linear correlation (r = -0.92, -0.93, t = 8.51, 9.76, p < 0.001, 0.001, respectively) were found between VP values and H120 and H90, respectively, while significant positive linear correlation (r = 0.95, t = 11.89, p < 0.001) was found between VP values and Delta H. CONCLUSION: The amount and degree of fat in the fatty liver can be assessed exactly by dual-energy CT. It will be a potential new effective method for quantitative diagnosis of fatty livers.
Fabrication of compact silver nanoshells on polystyrene spheres through electrostatic attraction.
Nanoshells composed of close-packed silver nanocrystals have been fabricated on polystyrene spheres via direct electrostatic attraction at appropriate pH; the thickness and roughness of the shell can be readily controlled through a layer-by-layer technique.
Evidence that APC regulates survivin expression: a possible mechanism contributing to the stem cell origin of colon cancer.
Because colorectal cancers (CRCs) frequently display APC mutation, inhibition of apoptosis, and increased expression of the antiapoptotic protein survivin, we hypothesized that APC mutation inhibits apoptosis by allowing constitutive survivin expression. Using HT-29 CRC cell lines having inducible wild-type APC (wt-APC) or transfected dominant-negative TCF-4, we show that wt-APC down-regulates survivin expression via APC/beta-catenin/TCF-4 signaling. Using normal colonic epithelium, we found survivin by immunostaining/reverse transcription-PCR to be preferentially expressed in the lower crypt (which inversely correlates with wt-APC's expression pattern). Thus, wt-APC, by progressively decreasing survivin and increasing apoptosis from crypt bottom to top, may limit the population size of stem cells and other proliferative cells in the lower crypt; mutant APC may allow expansion of these populations, thereby initiating tumorigenesis.
A miniature biofuel cell.
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A soluble class II cytokine receptor, IL-22RA2, is a naturally occurring IL-22 antagonist.
IL-22 is an IL-10 homologue that binds to and signals through the class II cytokine receptor heterodimer IL-22RA1/CRF2-4. IL-22 is produced by T cells and induces the production of acute-phase reactants in vitro and in vivo, suggesting its involvement in inflammation. Here we report the identification of a class II cytokine receptor designated IL-22RA2 (IL-22 receptor-alpha 2) that appears to be a naturally expressed soluble receptor. IL-22RA2 shares amino acid sequence homology with IL-22RA1 (also known as IL-22R, zcytor11, and CRF2-9) and is physically adjacent to IL-20Ralpha and IFN-gammaR1 on chromosome 6q23.3-24.2. We demonstrate that IL-22RA2 binds specifically to IL-22 and neutralizes IL-22-induced proliferation of BaF3 cells expressing IL-22 receptor subunits. IL-22RA2 mRNA is highly expressed in placenta and spleen by Northern blotting. PCR analysis using RNA from various tissues and cell lines showed that IL-22RA2 was expressed in a range of tissues, including those in the digestive, female reproductive, and immune systems. In situ hybridization revealed the dominant cell types expressing IL-22RA2 were mononuclear cells and epithelium. Because IL-22 induces the expression of acute phase reactants, IL-22RA2 may play an important role as an IL-22 antagonist in the regulation of inflammatory responses.
Platelet-derived growth factor C (PDGF-C), a novel growth factor that binds to PDGF alpha and beta receptor.
We have characterized platelet-derived growth factor (PDGF) C, a novel growth factor belonging to the PDGF family. PDGF-C is a multidomain protein with the N-terminal region homologous to the extracellular CUB domain of neuropilin-1, and the C-terminal region consists of a growth factor domain (GFD) with homology to vascular endothelial growth factor (25%) and PDGF A-chain (23%). A serum-sensitive cleavage site between the two domains allows release of the GFD from the CUB domain. Competition binding and immunoprecipitation studies on cells bearing both PDGF alpha and beta receptors reveal a high affinity binding of recombinant GFD (PDGF-CC) to PDGF receptor-alpha homodimers and PDGF receptor-alpha/beta heterodimers. PDGF-CC exhibits greater mitogenic potency than PDGF-AA and comparable or greater mitogenic activity than PDGF-AB and PDGF-BB on several mesenchymal cell types. Analysis of PDGF-CC in vivo in a diabetic mouse model of delayed wound healing showed that PDGF-CC significantly enhanced repair of a full-thickness skin excision. Together, these studies describe a third member of the PDGF family (PDGF-C) as a potent mitogen for cells of mesenchymal origin in in vitro and in vivo systems with a binding pattern similar to PDGF-AB.
Repopulation of liver endothelium by bone-marrow-derived cells.
The mechanism underlying the immunological advantage of hepatic allografts relative to other organs is incompletely understood. We used molecular probes for the repetitive units on the Y chromosome, to identify an increasing number of male liver venous endothelial cells in needle biopsy samples of men who received female donor liver grafts. We have also shown repopulation of liver endothelium by bone marrow derived cells in a male to female mouse bone marrow transplant model. We conclude that the liver has unique venous endothelium characterised by turnover and replacement by bone marrow derived cells.
Reactions of first-row transition metal ions with propargyl alcohol in the gas phase.
The gas-phase reactions with propargyl alcohol (PPA) of all the singly charged ions of the first-row transition metals, generated by laser ablation in an external ion source, were studied by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICRMS.). The reactivities of the metal ions change irregularly across the periodic table, and the reactivity of each ion is a function of its electronic configuration and corresponding metal-oxygen (M-O) bond energies. The 10 metal ions were classified into three categories according to their reactivities: Sc(+), Ti(+) and V(+) are the most reactive ions which react with PPA to give many kinds of oxygen-rich products due to stronger M-O bonds; Fe(+), Co(+) and Ni(+) are less reactive; Cr(+), Mn(+), Cu(+) and Zn(+) are the most unreactive ions, due to the half and completely occupied valence electronic configurations. The order of reactivity is Ti(+) > V(+) > Sc(+) >> Co(+) > Fe(+) approximately Ni(+) > Zn(+) > Cr(+) approximately Mn(+) approximately Cu(+).
Formation of binary alloy cluster ions from group-14 elements and cobalt and comparison with solid-state alloys.
By using laser ablation on mixtures of transition metal cobalt and group-14 elements, binary alloy cluster anions were produced while no binary alloy cluster cations were detected, and the homocluster cations of group-14 elements appeared at very low abundance. The differences between clustering abilities of germanium, tin and lead with cobalt are described, and the chemical bonds in the binary alloy cluster anions appear to indicate a transition from covalent to metal bonds. The cluster anion [CoPb10](-) appears in very high abundance (magic number), and an endohedral structure is proposed for this cluster. The cluster anion [CoPb12](-), also representing a magic number, probably has an icosahedral structure. Compared with solid-state Co/Ge binary alloys, the compositions of most binary alloy cluster anions are germanium-rich, in which the covalent bonds are predominant.
Protective effects of flavonoids in the roots of Scutellaria baicalensis Georgi against hydrogen peroxide-induced oxidative stress in HS-SY5Y cells.
Oxidative stress plays an important role in the pathological process of neurodegenerative diseases. The effects of four major flavonoids present in Scutellaria baicalensis Georgi on hydrogen peroxide-induced neuronal cell damage are studied in this paper. When human neuroblastoma SH-SY5Y cells were incubated in Hanks' solution with the addition of 400 microM hydrogen peroxide for 2 h, the viability of cells was decreased remarkably, while the cell lipid peroxidation and the percentage of lactose dehydrogenase released into the culture medium was significantly increased. Addition of 10 microM of baicalein and baicalin significantly attenuated the cellular injury induced by hydrogen peroxide, while the effect of wogonin was marginal and wogonoside showed no effect at the tested concentration. In a separate experiment, 10 microM of baicalein and baicalin also antagonized the intracellular free-calcium concentration ([Ca2+]i) increase caused by 1 mM hydrogen peroxide. The effects of baicalein in both experiments were similar to those of quercetin, a well-studied antioxidant flavonoid. These results demonstrated the protective effects of flavonoids originating from Scutellaria baicalensis Georgi on the oxidative injury of neuronal cells.