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Biomedical subjects

Hua Guo

Publications and source records attributed to Hua Guo.

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

[HER2 expression and its prognostic implication in lymph node negative breast carcinoma: a Meta-analysis].

OBJECTIVE: To evaluate the clinical value of HER2 overexpression in breast cancer and its prognostic implication in patients with lymph node negative breast carcinoma. METHODS: The following electronic database were extracted using appropriate inclusive and exclusive standards: Cochrane library, PUBMED, Embase (1984 - 2003), OVID, CMCC and CNKI. Excel and RevMan 4.2 were used for statistical analysis. RESULTS: Fifty-six articles were extracted to calculate the positive rate of HER2 overexpression. The pooled positive rate was 23.14% [19.54%, 26.73%], with positive immunohistochemistry (IHC) rate of 23.13% [19.49%, 26.77%] and positive FISH rate of 20.90% [15.54%, 26.25%]. Seven articles were used to evaluate prognostic predication of HER2 expression. It was concluded that in patients with lymph node negative breast carcinoma, HER2 overexpression (both IHC and FISH) independently predicted a poor prognosis based on disease-free survival (DFS) and overall survival (OS) with a P < 0.05. For DFS, the pooled RR was 1.38 [1.07, 1.80] with 1.16 [1.02, 1.31] for IHC and 1.98 [1.56, 2.52] for FISH. For OS, the pooled RR was 1.58 [1.16, 2.14] with 1.37 [1.14 to 1.64] for IHC and 2.33 [1.45 to 3.75] for FISH. HER2 overexpression effectively predicted DFS/OS of patients without adjuvant therapy and OS of patients with the therapy, but not for DFS, with the pooled RR of 1.46 [1.02, 2.09] and 1.11 [0.95, 1.31] for DFS, respectively and the pooled RR of 1.93 [1.44 to 2.58] and 1.25 [1.01, 1.56] for OS, respectively. CONCLUSIONS: In patients with lymph node negative breast carcinoma, the positive rate of HER2 overexpression is 23.14%. HER2 overexpression indicates a poor prognosis and adjuvant therapy after surgery should be recommended.

Breast Neoplasms↗
PubMed2005

[Inhibition of multidrug resistance related P-gp expression in human neuroblastoma by antisense peptide nucleic acid].

OBJECTIVE: To investigate the efficiency of a peptide nucleic acid (PNA) delivery system by using liposome via PNA-DNA hybrids and to test the inhibitive action of antisense PNA on expression of multidrug resistance (MDR) related P-glycoprotein (P-gp) in human neuroblastoma cell line SK-N-SH. METHODS: Two antisense PNAs were designed targeting at MDR-1 mRNA and then combined with partially complement DNAs respectively. The hybrids were delivered into cells using cationic liposome. The transfection efficiency, expression of P-gp and MDR-1 mRNA, intracellular adarimycin (ADM) were measured by flow cytometry, reverse transcription-polymerase chain reaction (RT-PCR), and high performance liquid chromatography (HPLC). RESULTS: Transfection of PNA increased the cell average fluorescence intensity significantly and the extent of increase was dependent on the concentration of PNA. After being transfected by both PNAs, P-gp expression of SK-N-SH cells decreased significantly and the intracellular ADM level was increased by about 3 times. The level of MDR-1 mRNA expression slightly decreased after transfection, but no statistical significance was observed. CONCLUSIONS: PNA can be delivered into tumor cells in form of PNA-DNA hybrids by cationic liposome. Properly designed antisense PNA can inhibit MDR related P-gp expression of SK-N-SH cells efficiently and specifically.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2005

[Effects of transforming growth factor-beta/Smad signaling on the growth and apoptosis of human rhabdomyosarcoma cell line RD].

OBJECTIVE: To study the effects of TGF-beta/Smad signaling on the growth and apoptosis of human rhabdomyosarcoma cell line RD. METHODS: Biosynthesized short hairpin RNA (shRNA) was transfected into RD cells by cation liposome vector to suppress Smad4 expression. The mRNA and protein expression of Smad4 in RD after shRNA-transfection were examined by RT-PCR and Western blot respectively. Immunofluorescent staining was used to detect the location of Smad2/3 in RD by laser scanning confocal microscopy. The viability of RD cells was examined by MTT method and (3)H-thymidine incorporation assay. The apoptosis of RD was examined by flow cytometry analysis and fluorescent staining. RESULTS: The expression of mRNA and protein of Smad4 in RD were effectively suppressed by shRNA interference. Such suppression effectively interrupted the endogenous TGF-beta/Smad signaling and consequently blocked the translocation of Smad2/3. The interruption of endogenous TGF-beta/Smad signaling not only inhibited the growth of RD but also induced apoptosis of RD. Exogenous TGF-beta1 inhibited the growth of RD but did not influence the apoptosis of RD. CONCLUSION: shRNA interference can effectively interrupt the TGF-beta/Smad signaling by suppressing the expression of Smad4. TGF-beta/Smad signaling subtly regulates the growth and apoptosis of RD.

Apoptosis↗
PubMed2004

QM/MM studies of the enzyme-catalyzed dechlorination of 4-chlorobenzoyl-CoA provide insight into reaction energetics.

The conversion of 4-chlorobenzoyl-CoA to 4-hydroxybenzoyl-CoA catalyzed by 4-chlorobenzoyl-CoA dehalogenase is investigated using combined QM/MM approaches. The calculated potential of mean force at the PM3/CHARMM level supports the proposed nucleophilic aromatic substitution mechanism. In particular, a Meisenheimer intermediate was found, stabilized by hydrogen bonds between the benzoyl carbonyl of the ligand and two backbone amide NHs at positions 64 and 114. Mutation of Gly113 to Ala significantly increases the barrier by disrupting the hydrogen bond with the Gly114 backbone. The formation of the Meisenheimer complex is accompanied by significant charge redistribution and structural changes in the substrate benzoyl moiety, consistent with experimental observations. Theoretical results suggest that the reaction rate is limited by the formation of the Meisenheimer complex, rather than by its decomposition. A kinetic model based on the calculated free energy profile is found to be consistent with the experimental time course data.

Acyl Coenzyme A↗
PubMed2004

Highly efficient, one-step macrocyclizations assisted by the folding and preorganization of precursor oligomers.

Highly efficient, one-step macrocyclizations leading to the formation of macrocyclic hexa(aramides) in high yields (69-82%) are described. The one-step macrocyclizations were facilitated by the preorganization or folding of the backbones of uncyclized precursors in the course of macrocyclization. The preorganization of backbones was achieved by the presence of localized three-centered hydrogen bonds that were adopted in the design of a class of closely related, backbone-rigidified foldamers. The macrocyclization involved reactions between diacid chloride 1 and diamine 2. The crude reaction mixtures and products were conveniently examined by mass spectrometric method (MALDI-TOF). Compared to most traditional one-step macrocyclizations that usually require high dilution conditions and often lead to very low overall yields of the desired products, cyclic hexamers 3 were obtained as the overwhelmingly major product under a variety of reaction conditions, suggesting the generality of this approach.

Cyclization↗
PubMed2004

An ab initio potential energy surface and vibrational states of MgH2(1(1)A').

A three-dimensional global potential energy surface for the ground electronic state of MgH(2) is constructed from more than 3000 ab initio points calculated using the internally contracted multireference configuration interaction method with the Davidson correction at the complete basis set limit. Low-lying vibrational energy levels of MgH(2) and MgD(2) are calculated using the Lanczos algorithm, and found to be in good agreement with known experimental band origins. The majority of the vibrational energy levels up to 8000 cm(-1) are assigned with normal mode quantum numbers. However, our results indicate a gradual transition from a normal mode regime for the stretching vibrations at low energies to a local mode regime near 7400 cm(-1), as evidenced by a decreasing energy gap between the (n(1),0,0) and (n(1)-1,0,1) vibrational states and bifurcation of the corresponding wave functions.

Journal Article↗
PubMed2004

Reactions of C(1D) with H2 and its deuterated isotopomers, a wave packet study.

Using a Chebyshev wave packet method, total and state-resolved reaction probabilities (J=0) were calculated for the reactions of C(1D) with various hydrogen isotopomers (H2, D2, and HD, nu i=0, j i=0) on a recent ab initio potential energy surface. For all the isotopic variants, it was found that the initial state specified reaction probabilities have no energy threshold and are strongly oscillatory, indicative of the involvement of long-lived resonances in this barrierless reaction. The J=0 product vibrational and rotational distributions for all three isotopic reactions, and the CH/CD branching ratio for the C+HD reaction, show strong dependence on the collision energy, further underscoring the important role played by the resonances. The generally decaying vibrational distributions and highly excited rotational distributions, which corroborate an insertion mechanism, and the dominance of the CD+H channel in the C+HD reaction are consistent with existing experimental observations. Initial state specified integral cross sections and rate constants were estimated using a capture model. The estimated rate constants were found to be close and in the order kHD>kH2>kD2. Finally, a method to calculate branching ratio in the C+HD reaction is proposed.

Journal Article↗
PubMed2004

A wave packet based statistical approach to complex-forming reactions.

A wave packet based statistical model is suggested for complex-forming reactions. This model assumes statistical formation and decay of the long-lived reaction complex and computes reaction cross sections and their energy dependence from capture probabilities. This model is very efficient and reasonably accurate for reactions dominated by long-lived resonances, as confirmed by its application to the C((1)D)+H(2) reaction.

Journal Article↗
PubMed2004

Immune activation set point during early HIV infection predicts subsequent CD4+ T-cell changes independent of viral load.

Although generalized T-cell activation is an important factor in chronic HIV disease pathogenesis, its role in primary infection remains poorly defined. To investigate the effect of immune activation on T-cell changes in subjects with early HIV infection, and to test the hypothesis that an immunologic activation "set point" is established early in the natural history of HIV disease, a prospective cohort of acutely infected adults was performed. The median density of CD38 molecules on CD4+ and CD8+ T cells was measured longitudinally in 68 antiretroviral-untreated individuals and 83 antiretroviral-treated individuals. At study entry, T-cell activation was positively associated with viremia, with CD8+ T-cell activation levels increasing exponentially at plasma HIV RNA levels more than 10,000 copies/mL. Among untreated patients, the level of CD8+ T-cell activation varied widely among individuals but often remained stable within a given individual. CD8+ T-cell activation and plasma HIV RNA levels over time were independently associated with the rate of CD4+ T-cell loss in untreated individuals. These data indicate that immunologic activation set point is established early in HIV infection, and that this set point determines the rate at which CD4+ T cells are lost over time.

Adult↗
PubMed2004

An ab initio potential energy surface and predissociative resonances of HArF.

A three-dimensional potential energy surface of the ground electronic state HArF is constructed from more than 2000 ab initio points at the multireference averaged quadratic coupled-cluster level employing an augmented large basis set. The calculations indicate that the linear HArF molecule is metastable with a barrier of 0.643 eV in the atomization (HArF --> H + Ar + F) channel and a barrier of 1.017 eV in the dissociation (HArF --> Ar + HF) channel. Variational calculations of low-lying predissociative resonances of both HArF and DArF are performed on the three-dimensional potential energy surface using a complex-symmetric Lanczos propagation method, which yields both positions and widths of the resonance states. The resonance lifetime generally decreases with energy, but strong mode selectivity exists. Reasonably good agreement with experiment confirms the accuracy of our potential. These calculations provide valuable information on the stability and dynamics of HArF/DArF in its ground electronic state.

Journal Article↗
PubMed2004

[Rat model for the multidrug resistant glioma cell line].

OBJECTIVE: To evaluate the animal model of the multidrug resistant glioma cell line C6/adr for further in vivo studies. METHODS: The rat glioma cells C6 and multidrug resistance cells C6/adr were cultured in vitro and implanted into the brain of S-D rats. After implantation, all these animals were examined continually with magnetic resonance imaging (MRI) and histological examination. The growth procedure of intracranial implanted glioma and the survival span of the animal model were evaluated. The statistical analysis was made between the survival data of the two cell lines. RESULTS: The symptoms of intracranial hypertension did not occur until 4 weeks after inoculation. The MRI findings of the implanted glioma in the rat brain were much earlier than the abnormal behavior observed. Pathological results after inoculation demonstrated the MRI findings. The two cell lines had similar growth characteristics and no significant differences in survival times. CONCLUSION: These results suggest that by means of MRI and histology the growth procedure of the implanted glioma in vivo be successfully observed. All these data will proved to be a useful basis for study of glioma in vivo.

Animals↗
PubMed2004

[Solitary fibrous tumor: the clinicopathologic and immunohistochemical characteristics of 26 cases].

OBJECTIVE: To study the clinicopathologic and immunohistochemical features of solitary fibrous tumor (SFT) and its biologic behaviour. METHODS: Clinicopathologic data of 26 cases were collected and analyzed. Among them, immunohistochemical staining (Envision method) for CD34, vimentin, CD99, bcl-2, S-100, SMA, HBME-1, EMA and Ki67 were performed in 23 cases. RESULTS: The 17 male and 9 female patients were between 15 and 66 years of age (mean, 44). Their SFTs were located in nose and nasopharynx, cranial cavity, soft tissue, mediastinum, and parietal and visceral pleura. The main clinical manifestations were local mass and pressure symptom. The characteristic microscopic features included patternless growth pattern, alternating hyper- and hypo-cellular areas, blunt spindle cells within keloid-like hyalinization, and hemangiopericytoma-like regions. Positive immunohistochemical staining: vimentin 100%(23/23), CD34 82%(19/23), bcl-2 87%(20/23), CD99 100%(23/23), SMA 30%(7/23). All cases were negative for S-100, HBME-1 and EMA. Follow-up information on 13 cases revealed that 3 patients had had relapse and died, the other 10 patients were alive without evidence of recurrence. CONCLUSION: SFT is a rare mesenchymal spindle cell tumor which may be found in various parts of human body and needs to be distinguished from other spindle cell tumors by differential diagnosis. The immunophenotype can be of help in this connexion. About 10% to 23% SFTs have malignant behaviour, manifesting as local recurrence or metastasis. The behavior of SFT is unpredictable, which requires careful, longterm follow-up.

12E7 Antigen↗
PubMed2004

[Progress in application of laser scanning confocal microscope to studies on dendritic cells].

The defensive function of immune response in vivo is very important. Antigen presenting cells (APC) is the hinge in starting specific immune response. Dendritic cells (DC) are the most potent APC, which participate in double-regulating the immune response. Laser scanning confocal microscope (LSCM) becomes a powerful tool in the fields of basic medicine and clinical medicine with its high resolving power, high sensitivity, optical section, three-dimensional reconstruction and dynamic analysis. And it makes the study on DC more thoroughly and deeper. In this paper, we review the recent progress in the applications of LSCM to studies on the morphology, immunofluorescence localization and the functional analysis of dendritic cells.

Dendritic Cells↗
PubMed2004

[Determination of germanium in aloe vera by spectrophotometric method].

OBJECTIVE: To analyze the organic germanium in aloe vera from different localities. METHODS: The method was based on germanium forms a stable complex with phenylfluorone in the acidified solution and CTMAB as solubilization agent. The contents of the organic germanium in Aloe vera from different localities were determined by spectrophotometric methods. RESULTS: The linear range of determination is 0-0.7 microg/ml. The recovery is 98.1%-99.0% and the coefficient of variation is 1.8%.

Aloe↗
PubMed2003

[The phenotypic transformation of renal tubular epithelial cells affected by pathological stimuli].

OBJECTIVE: To investigate the effects of low bovine serum, high glucose and high albumin on the phenotypic transformation of cultured renal tubular epithelial cells to mesenchymal cells. METHODS: The human kidney proximal tubular cells were cultured for 7 days in the presence of low bovine serum (0.2 mol.L-1), high glucose (4.5 g.L-1) and high albumin (15 g.L-1), and morphological changes were assessed by electronic microscopy, immunohistochemistry stain and Western blot to show the phenotypic changes, including the expressions of cytokeratin, vimentin, collagen I and III, alpha-SMA, and TGF beta 1. The expression of collagen I mRNA was assessed by in situ hybridization. RESULTS: Renal tubular epithelial cells cultured in low bovine serum, high glucose and high albumin, showed obvious morphologic changes, including elongated shape, reducing of microvillus and mitochondria, increasing of rough endoplasmic reticulum, and the appearance of actin microfilaments. Immunohistochemistry stain and Western blot showed the low expression of cytokeratin and high expression of vimentin, collagen types I and III, alpha-SMA, and TGF beta 1. The increasing expression of collagen I mRNA was assessed by in situ hybridization. CONCLUSION: Lower bovine serum, high glucose and high albumin can induce the expression of TGF beta, and lead to the phenotypic transformation of tubular epithelial cells to mesenchymal cells.

Cells, Cultured↗
PubMed2003

Single-shot spiral image acquisition with embedded z-shimming for susceptibility signal recovery.

PURPOSE: To efficiently and effectively recover the susceptibility-induced signal losses for functional MRI (fMRI) experiments. MATERIALS AND METHODS: The signal losses near air/tissue interfaces at the ventral brain regions introduce difficulties in the neuroimaging studies concerned with brain functions such as memory, emotion, and olfaction processes. The z-shimming technique has been introduced in fMRI image acquisition to recover such losses. One significant drawback of such an approach is its time consuming nature. In this report, a single-shot spiral imaging method, which combines spiral-in and spiral-out acquisitions along with embedded z-shimming gradient, was proposed and implemented to achieve signal recovery without sacrificing temporal resolution. RESULTS: Using the proposed method, final images were shown in the ventral brain regions. The images were acquired with a throughput of 16 slices/second and demonstrated effectiveness and efficiency in signal recovery near air/tissue interfaces. CONCLUSION: Uniform recovery can be achieved efficiently near air/tissue interfaces where susceptibility-induced spatial gradients are pronounced. We anticipate that our method would be well suited for fMRI studies involving the ventral brain areas.

Brain↗