Biomedical subjects

Hui Zhang

Publications and source records attributed to Hui Zhang.

At least 199 records · Page 11Linked to original sources

PubMed2005

Two-stage registration for real-time deformable compensation using an electromagnetic tracking device.

Electromagnetic tracking systems have the potential to track instruments inside the body because they are not limited by the line of sight constraints that characterize optical tracking systems. To integrate an electromagnetic tracking device into a surgical navigation system, accurate registration is required. We present a two-stage registration mechanism designed to be more accurate than the widely used global fiducial-based registration method. The first stage uses a hybrid Iterative Closest Point (ICP) registration method and the Simulated Annealing (SA) optimization algorithm, to increase the initial registration accuracy. The second stage exploits multiple implanted tracking needles that are used to calculate the affine transform based on the initial transform information, and thereby to compensate for the deformation in real time. Phantom and swine studies have demonstrated the utility of this technique.

Animals↗

PubMed2005

Statistical modeling of shape and appearance using the continuous medial representation.

We describe a novel approach to combining shape and appearance features in the statistical analysis of structures in medical images. The continuous medial representation is used to relate these two types of features meaningfully. The representation imposes a shape-based coordinate system on structure interiors, in a way that uses the boundary normal as one of the coordinate axes, while providing an onto and nearly one-to-one parametrization. This coordinate system is used to sample image intensities in the context of shape. The approach is illustrated by the principal components analysis of the shape and appearance of the hippocampus in T1-weighted MRI from a schizophrenia study.

Algorithms↗

PubMed2005

Mitochondrial function in fibroblasts with aging in culture and/or Alzheimer's disease.

Mitochondrial membrane potentials (MMP) reflect the functional state of the mitochondria within cells. Our recently published method provides a quantitative estimate of the MMP of populations of mitochondrial-like particles (MLP) within living cells at 37 degrees C using the combination of conventional fluorescence microscopy, 3D-deconvolution and exhaustive photon reassignment (EPR). Although the method does not provide an absolute measure of MMP, these relative MMP allow direct comparison between various mitochondria in cells at various ages in culture and in different cell lines from multiple patients. Fibroblasts lines from four Alzheimer's disease (AD) patients bearing the presenilin-1 (PS-1) mutation and four appropriate controls were evaluated at different ages in culture. The results showed a large variation in the relative MMP, cell size and sum of relative MMP of all MLP within each cell or within each cell line. Nevertheless, combining the values of relative MMP for the cell lines in each group revealed changes in distribution with age in culture. The relative MMP decreased while the cell sizes and sum of relative MMP within each cell increased with age in fibroblasts. Values did not differ between controls and the AD patients bearing PS-1 mutation at any age in cultures. This new, sensitive and quantitative estimate of relative MMP indicates that under non-stressed conditions relative MMP change with aging in culture, but relative MMP do not differ between controls and AD subjects.

Adult↗

PubMed2005

The experimental study on the radioimmunotherapy of the nasopharyngeal carcinoma overexpressing HER2/neu in nude mice model with intratumoral injection of 188Re-herceptin.

The therapeutic efficacy of radioimmunotherapy (RIT) of 188Re-labeled herceptin, which is a humanized anti-p185-HER2/neu monoclonal antibody (mAb), was studied. The nude mice bearing nasopharyngeal carcinoma (NPC) expressing HER2/neu protooncogene were injected with 188Re-herceptin intratumorally and intravenously. The biodistribution was observed on day 2 (n = 3). The tumor growth inhibition rate (IR) was determined by measurement of tumor volume. In the intratumorally treated mice, tumor uptake of 188Re-herceptin was significantly greater than in the intravenously treated mice [11.53% injected dose (ID)/g vs. 2.79% ID/g at 48 h], and lower normal organ uptake was also seen. The intratumoral administration of 188Re-herceptin caused greater inhibition of tumor growth at the fourth week as compared to the intravenous administration. It is concluded that intratumoral administration of 188Re-herceptin makes high level of radioactivity retained in tumor with significantly lower radioactivity retained in normal tissues, and provides a more effective regional therapy for NPC overexpressing HER2/neu.

Animals↗

PubMed2005

Flow injection kinetic spectrofluorimetric determination of trace amounts of osmium.

A flow injection (FI) kinetic spectrofluorimetric method is described for the determination of osmium(IV) and the possible mechanism of catalytic reaction is discussed. The method is based on the fluorescence enhancing reaction of o-vanillin furfuralhydrazone (OVFH) with potassium bromate, which is catalyzed by Os(IV) in water medium at pH 6.10 and 45 degrees C. OVFH is newly synthesized and its ionization, IR and elemental analysis are established. Under these experimental conditions, the oxidized product of OVFH has excitation and emission maxima at 337 and 490 nm, respectively. The linear range of this method is 0-600 ng ml(-1) with the R.S.D. of 1.2%. The detection limit is 1.0 ng ml(-1) of Os(IV). A high analysis rate of 24 samples h(-1) is obtained by the FI method. The proposed method is applied successfully to determine Os(IV) in synthetic mixture and mineral samples, and the results are well consistent with the standard values.

Benzaldehydes↗

PubMed2005

Gold nanocages: bioconjugation and their potential use as optical imaging contrast agents.

Gold nanocages of <40 nm in dimension have been synthesized using the galvanic replacement reaction between Ag nanocubes and HAuCl4 in an aqueous solution. By controlling the molar ratio between Ag and HAuCl4, the gold nanocages could be tuned to display surface plasmon resonance peaks around 800 nm, a wavelength commonly used in optical coherence tomography (OCT) imaging. OCT measurements on phantom samples indicate that these gold nanocages have a moderate scattering cross-section of approximately 8.10 x 10(-16) m2 but a very large absorption cross-section of approximately 7.26 x 10(-15) m2, suggesting their potential use as a new class of contrast agents for optical imaging. When bioconjugated with antibodies, the gold nanocages have also been demonstrated for specific targeting of breast cancer cells.

Cell Line, Tumor↗

PubMed2005

Exogenous IL-7 induces Fas-mediated human neuronal apoptosis: potential effects during human immunodeficiency virus type 1 infection.

The use of exogenous cytokines is part of translational immune-antiretroviral approaches to induce immune reconstitution and possibly eliminate the persistence of human immunodeficiency virus type 1 (HIV-1) in virally suppressed infected individuals on highly active antiretroviral therapy (HAART). Recently, our laboratories demonstrated that interleukin-7 (IL-7) has significant efficiency in stimulating HIV-1 replication from proviral latency in CD4+ T lymphocytes of infected patients. The authors now investigated the possible role of IL-7 in HIV-1-associated dementia (HAD). The authors demonstrated that the IL-7 receptor is expressed on both human neurons (i.e., differentiated NT2 cells) and human astrocytes, with relatively higher mRNA levels in neurons. The translational protein levels of IL-7 receptor alpha were not proportional to those of the mRNA levels in these central nervous system (CNS)-based cell types. Exogenous IL-7 was observed to only slightly down-regulate IL-7 receptor alpha expression on both neurons and astrocytes, as assayed by Western blotting. Instead of promoting survival, surprisingly, exogenous IL-7 induced neuronal apoptosis, as detected by TUNEL assays. Furthermore, IL-7 augmented neuronal apoptosis induced by HIV-1 gp120. Human apoptosis genomic microarray analyses of IL-7-treated human neurons showed up-regulated expression of proapoptotic genes: protein kinases, caspase-10, FAST kinase, tumor necrosis factor (TNF) receptor, and BCL2-antagonist of cell death. These data suggest that IL-7 leads to neuronal apoptosis by a molecular mechanism(s) that occurs via Fas-mediated activation-induced cell death. These studies may therefore not only be key in evaluating the potential use of IL-7 in vivo as a therapeutic modality, but also suggest that IL-7, which is increased endogenously in HIV-1-infected individuals late in disease, may be involved in the neuronal apoptosis demonstrated during HAD.

Apoptosis↗

PubMed2005

The quality of care under a managed-care program for dual eligibles.

PURPOSE: Our objective in this study was to compare the quality of care provided under the Minnesota Senior Health Options (MSHO), a special program designed to serve dually eligible older persons, to care provided to controls who received fee-for-service Medicare and Medicaid managed care. DESIGN AND METHODS: Two control groups were used; one was drawn from nonenrollees living in the same area (Control-In) and another from comparable individuals living in another urban area where the program was not available (Control-Out). Cohorts living in the community and in nursing homes were included. Quality measures for both groups included mortality rates, preventable hospital admissions, and preventable emergency room (ER) visits. For the community group, nursing home admission rates were also tracked. For nursing home residents, quality measures included quality indicators derived from the Minimum Data Set. RESULTS: There were no differences in mortality rates for either cohort. MSHO had fewer short-stay nursing home admissions but no difference for stays 90 days or longer. MSHO community and nursing home residents had fewer preventable hospital and ER visits compared to Control-In. There were no major differences in nursing home quality indicator rates. IMPLICATIONS: The cost of changing the model of care for dual eligibles from a mixture of fee-for-service and managed care to a merged managed-care approach cannot be readily justified by the improvements in quality observed.

Aged↗

PubMed2005

Analysis of prostate cancer by proteomics using tissue specimens.

PURPOSE: Prostate cancer cells differ from their normal counterpart in gene expression. Therefore, cancer and normal tissue/cells would show differences in their proteomes. From a diagnostic standpoint differences in the composition of secreted protein species are especially relevant. We used ProteinChip Array (Ciphergen Biosystems, Fremont, California) surface enhanced laser desorption/ionization (SELDI) time of flight mass spectrometry to profile prostate tissue samples to generate phenomic fingerprints. We used quantitative proteomics based on glycopeptide capture followed by tandem mass spectrometry to identify differentially expressed proteins. MATERIALS AND METHODS: Patient matched cancer and noncancer specimens were digested by collagenase to single cells. After digestion the cells were pelleted and the cell-free supernatant was used for analysis. A reversed phase hydrophobic ProteinChip Array was used to generate SELDI patterns from 43 primary prostate tumors, including 26 with matched noncancer specimens. Quantitative proteomics was applied to 1 specimen and the expression pattern was verified by Western blotting and immunohistochemistry. RESULTS: SELDI profiles showed that cancers of similar TNM stages were more likely to have similar profiles. On quantitative proteomics tissue metalloproteinase inhibitor-1 was identified to be down-regulated in cancer. Tissue metalloproteinase inhibitor-1 expression was localized to secretory cells. CONCLUSIONS: Protein profiling by SELDI is relatively easy to perform and it has great potential in prostate cancer diagnosis through pattern recognition. Quantitative proteomics can potentially determine the identity of many biomarkers specific for prostate cancer.

Biomarkers, Tumor↗

PubMed2005

Navigation with electromagnetic tracking for interventional radiology procedures: a feasibility study.

PURPOSE: To assess the feasibility of the use of preprocedural imaging for guide wire, catheter, and needle navigation with electromagnetic tracking in phantom and animal models. MATERIALS AND METHODS: An image-guided intervention software system was developed based on open-source software components. Catheters, needles, and guide wires were constructed with small position and orientation sensors in the tips. A tetrahedral-shaped weak electromagnetic field generator was placed in proximity to an abdominal vascular phantom or three pigs on the angiography table. Preprocedural computed tomographic (CT) images of the phantom or pig were loaded into custom-developed tracking, registration, navigation, and rendering software. Devices were manipulated within the phantom or pig with guidance from the previously acquired CT scan and simultaneous real-time angiography. Navigation within positron emission tomography (PET) and magnetic resonance (MR) volumetric datasets was also performed. External and endovascular fiducials were used for registration in the phantom, and registration error and tracking error were estimated. RESULTS: The CT scan position of the devices within phantoms and pigs was accurately determined during angiography and biopsy procedures, with manageable error for some applications. Preprocedural CT depicted the anatomy in the region of the devices with real-time position updating and minimal registration error and tracking error (<5 mm). PET can also be used with this system to guide percutaneous biopsies to the most metabolically active region of a tumor. CONCLUSIONS: Previously acquired CT, MR, or PET data can be accurately codisplayed during procedures with reconstructed imaging based on the position and orientation of catheters, guide wires, or needles. Multimodality interventions are feasible by allowing the real-time updated display of previously acquired functional or morphologic imaging during angiography, biopsy, and ablation.

Angiography↗

PubMed2005

Electrode effects on frequency spectra and electromechanical coupling factors of HBAR.

In this paper, effects of electrodes on the spectra of high-overtone bulk acoustic resonator are analyzed phenomenologically by numerical simulations. Acoustic impedance ratio of the substrate to piezo-film, Zsb/Z0, and acoustic impedance ratio of the electrode to piezo-film, Ze/Z0, are taken as the category parameters for different combinations of three kinds of substrates, three kinds of piezo-films, and seven kinds of electrodes. The numerical simulations for all of the combinations are carried out. The results indicate that the acoustic impedance ratio of the substrate to piezo-film is a key factor for the variations of the space of parallel resonance frequency and the effective coupling factor versus the mode order. The mechanical effects of the electrodes have significant contribution as well. Several approximate formulae are given to evaluate the effective coupling factor for different combinations.

Journal Article↗

PubMed2005

Prevalence and significance of anti-HLA and donor-specific antibodies long-term after renal transplantation.

Post-transplant circulating anti-human leukocyte antigens (HLA)-antibodies and C4d in allograft biopsies may be important in chronic rejection in renal transplant recipients (RTR). We determined the prevalence and significance of anti-HLA-antibodies and donor-specific antibodies (DSA). Sera were collected from 251 RTR >6 months post-transplant. Sera were tested using enzyme-linked immunosorbent assay (ELISA) screening for anti-HLA antibodies. Positive sera were retested with ELISA-specific panel for antibody specificity. A 11.2% of patients had anti-HLA antibodies and 4.4% had DSA. Anti-HLA antibodies were significantly associated with pretransplant sensitization, acute rejection and in multivariate analysis, higher serum creatinine (2.15 +/- 0.98 vs. 1.57 +/- 0.69 mg/dl in negative anti-HLA antibodies group). Allograft biopsies performed in a subset of patients with anti-HLA antibodies revealed that 66% had C4d in peritubular capillaries (0% in patients without antibodies). Anti-HLA antibodies were associated with a worse allograft function and in situ evidence of anti-donor humoral alloreactivity. Long-term RTR with an increase in creatinine could be screened for anti-HLA antibodies and C4d in biopsy.

Adolescent↗

PubMed2005

Neurotoxicity and behavioral deficits associated with Septin 5 accumulation in dopaminergic neurons.

Septin 5, a parkin substrate, is a vesicle- and membrane-associated protein that plays a significant role in inhibiting exocytosis. The regulatory function of Septin 5 in dopaminergic (DAergic) neurons of substantia nigra (SN), maintained at relatively low levels, has not yet been delineated. As loss of function mutations of parkin are the principal cause of a familial Parkinson's disease, a prevailing hypothesis is that the loss of parkin activity results in accumulation of Septin 5 which confers neuron-specific toxicity in SN-DAergic neurons. In vitro and in vivo models were used to support this hypothesis. In our well-characterized DAergic SN4741 cell model, acute accumulation of elevated levels of Septin 5, but not synphilin-1 (another parkin substrate), resulted in cytotoxic cell death that was markedly reduced by parkin co-transfection. A transgenic mouse model expressing a dominant negative parkin mutant accumulated moderate levels of Septin 5 in SN-DAergic neurons. These mice acquired a progressive l-DOPA responsive motor dysfunction that developed despite a 25% higher than normal level of striatal dopamine (DA) and no apparent loss of DAergic neurons. The phenotype of this animal, increased striatal dopamine and reduced motor function, was similar to that observed in parkin knockout animals, suggesting a common DAergic alteration. These data suggest that a threshold level of Septin 5 accumulation is required for DAergic cell loss and that l-DOPA-responsive motor deficits can occur even in the presence of elevated DA.

Animals↗

PubMed2005

Mechanism of protective action of bicyclol against CCl-induced liver injury in mice.

Bicyclol is a novel synthetic drug for the treatment of chronic viral hepatitis in China. This paper reports the protective action of bicyclol against experimental liver injury in mice and its mechanism of action. Oral administration of bicyclol markedly reduced the elevated serum transaminases (alanine aminotransferase (ALT) and aspartate aminotransferase (AST)) and the hepatic morphologic changes induced by CCl(4) in mice. Mechanistic studies demonstrated that bicyclol significantly inhibited CCl(4)-induced lipid peroxidation of liver microsomes and (14)CCl(4) covalent binding to microsomal lipids and proteins in vitro, and decreased the level of the trichloromethyl free radical (*CCl(3)) generated from CCl(4) metabolism by NADPH-reduced liver microsomes. On the other hand, bicyclol neither directly inhibited the activity of ALT or AST in vitro nor affected hepatic ALT protein content in mice. These results suggest that bicyclol has remarkable hepatoprotective effects and its mechanism of action may be related to a decrease in free radical-induced damage to hepatocytes.

Administration, Oral↗

PubMed2005

Structural and spectroscopic properties of a reaction center complex from the chlorosome-lacking filamentous anoxygenic phototrophic bacterium Roseiflexus castenholzii.

The photochemical reaction center (RC) complex of Roseiflexus castenholzii, which belongs to the filamentous anoxygenic phototrophic bacteria (green filamentous bacteria) but lacks chlorosomes, was isolated and characterized. The genes coding for the subunits of the RC and the light-harvesting proteins were also cloned and sequenced. The RC complex was composed of L, M, and cytochrome subunits. The cytochrome subunit showed a molecular mass of approximately 35 kDa, contained hemes c, and functioned as the electron donor to the photo-oxidized special pair of bacteriochlorophylls in the RC. The RC complex appeared to contain three molecules of bacteriochlorophyll and three molecules of bacteriopheophytin, as in the RC preparation from Chloroflexus aurantiacus. Phylogenetic trees based on the deduced amino acid sequences of the RC subunits suggested that R. castenholzii had diverged from C. aurantiacus very early after the divergence of filamentous anoxygenic phototrophic bacteria from purple bacteria. Although R. castenholzii is phylogenetically related to C. aurantiacus, the arrangement of its puf genes, which code for the light-harvesting proteins and the RC subunits, was different from that in C. aurantiacus and similar to that in purple bacteria. The genes are found in the order pufB, -A, -L, -M, and -C, with the pufL and pufM genes forming one continuous open reading frame. Since the photosynthetic apparatus and genes of R. castenholzii have intermediate characteristics between those of purple bacteria and C. aurantiacus, it is likely that they retain many features of the common ancestor of purple bacteria and filamentous anoxygenic phototrophic bacteria.

Amino Acid Sequence↗

PubMed2005

Chronic alcohol consumption in mice increases the proportion of peripheral memory T cells by homeostatic proliferation.

This study examined the mechanism underlying the increase of peripheral memory phenotype T cells that occurs during chronic alcohol consumption in mice. Female C57BL/6 mice were given 20% (w/v) alcohol in the drinking water for 2 weeks to 6 months. Chronic alcohol consumption significantly induced peripheral T cell lymphopenia; up-regulated expression of CD44 on T cells and increased the percentage of CD4+CD44int/hi and CD8+CD44int/hi Ly6C+ T cells; up-regulated the expression of CD43 on CD8+ T cells; increased the percentage of interferon--producing T cells; decreased the percentage of CD8+CD28+ T cells; and down-regulated the expression of CD28 on CD4+ T cells. Expression of CD25 and CD69 on peripheral CD8+ T cells was not affected and inconsistently expressed on CD4+ T cells. Neither cell type showed altered expression of CD137 or CD153. Alcohol withdrawal did not abrogate the increase in CD8+Ly6C+cells induced by alcohol consumption. In vivo bromodeoxyuridine incorporation experiments demonstrated that chronic alcohol consumption decreases naïve T cells that are presumed to have emigrated from the thymus and increases proliferation of memory T cells, but accelerates peripheral T cell turnover. Together these results indicate that chronic alcohol consumption results in T cell lymphopenia, which in turn induces T cell homeostatic proliferation that increases the proportion of peripheral memory T cells relative to naïve T cells.

Alcoholism↗

PubMed2005

Pathogenic T-cell recruitment into the airway in human disease.

Effector T cells significantly contribute to inflammatory diseases. These cells are recruited into tissue, where they orchestrate an inflammatory response that can either protect against infection or sometimes stimulate human disease. The recruitment of T cells into tissue from the blood and lymphoid compartments is an active process controlled by chemokines and the chemokine receptors expressed on distinct effector T-cell subsets. Thus, the chemokines secreted in the tissue will determine the specific types of T lymphocyte recruited into that tissue based on the chemokine receptors expressed on these cells. It follows that the chemokine receptor profile on T cells isolated from the lungs of patients with inflammatory pulmonary disease will define the subtype of pathogenic T lymphocytes mediating the disease process and will identify the mechanisms that recruit these cells into the lung. This article reviews data from both human and animal studies that define the chemokine receptors involved in the recruitment of T lymphocytes into the lung in various inflammatory pulmonary diseases, including asthma, obliterative bronchiolitis, sarcoidosis, and chronic eosinophilic pneumonia. We then speculate on the potential role of these chemokine receptors in the pathogenesis of these disorders and potential novel therapeutic approaches suggested by these data.

Animals↗

PubMed2005

Investigation on liver function among population in high background of rare earth area in South China.

The health effects of long-term ingestion of rare earth elements (REEs) on the villagers living in high-REE-background areas in South Jangxi Province, China were studied. Major health complaints from the REE area population included indigestion, diarrhea, abdominal distension, anorexia, weakness, and fatigue, especially after high-fat or high-protein intake. Liver function tests were conducted for adult villagers. Among them, 45 live in a heavy rare earth (HREE) area, 62 in a light rare earth (LREE) area, and 49 in the control area. Test results showed that serum total protein and globulin from both HREE and LREE areas, as well as albumin from the LREE area, were significantly lower (p < 0.01 - 0.01) compared to the results from the control area, whereas albumin from the HREE area showed no significant variance (p > 0.05). The chi-square test showed that Serum-glutamic pyruvic transaminase (SGPT) in both areas were not significant (p > 0.05), whereas the IgM in the HREE area was significantly elevated. It is our conclusion that long-term ingestion of REE affected activities of some digestive enzymes, causing malabsorption and indigestion, and might further lead to a low-protein effect for the villagers in the LREE area. However, the damage to the liver was rather mild. The elevation of IgM was probably the result of stimulation induced by the formation of a large amount of granules as a result of direct binding of REEs to globulin or albumin (combination of REEs with globulin or albumin).

Adult↗