Biomedical subjects

Hong Zhang

Publications and source records attributed to Hong Zhang.

At least 217 records · Page 12Linked to original sources

PubMed2005

Expression of NF-kappaB in hRPE cells stimulated by PDTC and IL-1beta.

The constitutive expression of nuclear-factor-kappaB (NF-kappaB) in human pigment epithelial (hRPE) cells cultivated in vitro and the possible changes when incubated with PDTC and IL-1beta were investigated. The synchronized hRPE cells in vitro were divided into two groups. In non-PDTC group, hRPE cells were exposed respectively to IL-1beta and NS (for detecting the constitutive expressions of NF-kappaB in hRPE cells); In PDTC group, PDTC-pretreated hRPE cells were exposed respectively to IL-1beta and NS (for detecting the constitutive expression of NF-kappaB in PDTC-pretreated hRPE cells). The expression of NF-kappaB in hRPE cells in two groups was detected by immunofluorescence stain and flow cytometry. The results showed that the constitutive expression of NF-kappaB in hRPE cells in vitro was 8.05%, and increased to 30.26% by IL-1beta. After PDTC pretreatment, the constitutive expression of NF-kappaB in hRPE cells was decreased to 3.74%, and 3.66% by IL-1beta respectively. It was concluded that the expressions of NF-kappaB in hRPE cells could be increased significantly by IL-1beta and depressed effectively by PDTC. Also, PDTC could significantly inhibit the activation of NF-kappaB induced by IL-1beta.

Cells, Cultured↗

PubMed2005

Hexokinase-II expression in untreated oral squamous cell carcinoma: comparison with FDG PET imaging.

Hexokinase is thought to be one of the key factors of glucose catabolism in the cell. The aim of this study was to investigate the relationship between HK-II expression and 18F-fluoro-2-deoxy-D-glucose (FDG) uptake in human untreated oral squamous cell carcinoma (OSCC). Pre-operatively FDG positron emission tomography (PET) was performed 60 min after FDG injection in all the patients. Maximum standardized uptake value (SUV) was used for evaluation of tumor FDG uptake. Tumor sections were stained immunohistochemically for HK-II. All the tumor sections stained positive for HK-II. Eighteen (95%) tumors in HK-II showed immunostained positive area >50%. HK-II findings revealed eleven (58%) tumors with strong intensity, six (32%) with moderate intensity and two with weak intensity (10%). There was no statistically significant correlation between SUV and the expression of HK-II (p = 0.46). In conclusion, OSCC showed increased FDG accumulation and overexpression of HK-II. However, we did not find any significant relationship between high FDG uptake and overexpression of HK-II in this patient population, and thus other properties need to be evaluated in order to elucidate key factors responsible for FDG activity in OSCC.

Adult↗

PubMed2005

Gender differences in bone density at different skeletal sites of acquisition with age in Chinese children and adolescents.

Bone mass acquisition from different genders and races of children and adolescents may vary. To explore gender- and age-related differences in bone mineral density (BMD) measurements in Chinese children and adolescents, we used the dual-energy X-ray absorptiometry (DXA) bone densitometer to take BMD measurements at the posteroanterior (PA) and lateral spine, hip, and forearm in 1286 healthy children and adolescents, ranging from 6 to 24 years of age. Our results show a correlation between BMD measurements taken from different skeletal sites and from different ages of subjects. Male data were best fit to a power regression model, yielding the largest determinant coefficients (R (2)), whereas S regression was the best fitting model for females. In individuals younger than 17 years of age, the rate of BMD accumulation in the PA spine is more rapid in females than in males, whereas in individuals older than 19 years of age, the converse was found to be true. In children younger than 14 years of age, BMD measurements, taken from the lateral spine, the neck and trochanter of the femur, and the total hip, correlated with age similarly in both genders. Additionally, in measurements taken from the forearm ultradistal and 1/3 region, BMD measurements from similar ages of both genders are similar. With increasing age, BMD measurements in males become significantly higher than those of females. However, volumetric BMD (vBMD) measurements from both genders show good uniformity at the lateral spine with a near overlap of the two models. Our findings suggest that vBMD acquisition measurements in Chinese children and adolescents show no gender differences, with gender differences only demonstrated in areal BMD (aBMD) measurements taken from different skeletal sites.

Absorptiometry, Photon↗

PubMed2005

Routine human immunodeficiency virus testing: an economic evaluation of current guidelines.

BACKGROUND: The Centers for Disease Control and Prevention guidelines recommend human immunodeficiency virus (HIV) counseling, testing, and referral for all patients in hospitals with an HIV prevalence of >or=1%. The 1% screening threshold has not been critically examined since HIV became effectively treatable in 1995. Our objective was to evaluate the clinical effect and cost-effectiveness of current guidelines and of alternate HIV prevalence thresholds. METHODS: We performed a cost-effectiveness analysis using a computer simulation model of HIV screening and disease as applied to inpatients in U.S. hospitals. RESULTS: At an undiagnosed inpatient HIV prevalence of 1% and an overall participation rate of 33%, HIV screening increased mean quality-adjusted life expectancy by 6.13 years per 1000 inpatients, with a cost-effectiveness ratio of 35,400 dollars per quality-adjusted life-year (QALY) gained. Expansion of screening to settings with a prevalence as low as 0.1% increased the ratio to 64,500 dollars per QALY gained. Increasing counseling and testing costs from 53 dollars to 103 dollars per person still yielded a cost-effectiveness ratio below 100,000 dollars per QALY gained at a prevalence of undiagnosed infection of 0.1%. CONCLUSION: Routine inpatient HIV screening programs are not only cost-effective but would likely remain so at a prevalence of undiagnosed HIV infection 10 times lower than recommended thresholds. The current HIV counseling, testing, and referral guidelines should now be implemented nationwide as a way of linking infected patients to life-sustaining care.

Centers for Disease Control and Prevention, U.S.↗

PubMed2005

Acetabular medial wall displacement osteotomy in total hip arthroplasty: a technique to optimize the acetabular reconstruction in acetabular dysplasia.

Twenty-six patients (30 hips) who had acetabular dysplasia were operated on by circumferential acetabular medial wall displacement osteotomy to reconstruct the acetabulum during total hip arthroplasty. All patients had cementless acetabular components implanted. The average acetabular component size was 50 mm (range, 44-56 mm). Only 2 hips needed structural bone graft. The mean follow-up period was 22 months (range, 6-32 months). Harris hip score had changed from 47.31 (range, 19-69 points) to 94.69 (range, 85-100 points) postoperatively (P < .01). Using the Ranawat acetabular triangle to determine the optimal hip center of rotation, the postoperative hip biomechanical environment had been improved. Our short-term follow-up suggests this technique is reliable and reproducible and generally avoids the use of bone graft and graft site morbidity. In addition, it allows the use of standard modular cementless components in patients with acetabular dysplasia.

Acetabulum↗

PubMed2005

Classification and ordination of DDT and HCH in soil samples from the Guanting Reservoir, China.

Organochlorine pesticides (OCPs) have been a major environmental issue, drawing much scientific and public attention due to their bioaccumulation potential, persistence and toxicity. Soil samples from three villages around the Guanting Reservoir, one of Beijing's five major water systems located to the northwest of the city, were collected in 2003 and analyzed to determine DDT and HCH-concentrations. The samples were also analyzed for soil texture, pH, and concentrations of total carbon, nitrogen and phosphorus to investigate their possible relationship to current OCP-concentrations. Hierarchical Cluster Analysis (HCA) and Principal Component Analysis (PCA) were used to study the distribution and contamination levels of OCPs within the study area. Classification splits were made to divide the 30 samples into three groups. The first group contained samples in soils from village C; the second group contained all of the samples in village B and most of the samples in village A; and the third group contained just three samples from village A, and the three samples had a relatively high concentration of OCPs. Ordination plots of the first two axes from PCA (cumulative percentage 80.91%) were constructed to explore the HCH and DDT-distribution patterns as well as the degradation ratios between the parent substances and their isomers.

China↗

PubMed2005

A spatial temporal assessment of pollution from PCBs in China.

This research represents an assessment of the current state of pollution from polychlorinated biphenyls (PCBs) in China. Various environmental media including sediment, water, organism and soil were analyzed and the spatial character of PCB pollution in each environmental medium was determined. On a national basis, PCB levels in all environmental media were relatively low, with little evidence of major contamination in China's main regions and rivers. However, there were some locations with high PCB concentrations. Sediments in Pearl River (83.1 ng/g) and its estuary (58.9 ng/g), Dalian Bay (58.1 ng/g) and Songhua River (36.8 ng/g) had relatively high level of PCBs. There were also some areas, which were mainly the industrial pollution sites or PCB equipment storage locations, remained seriously polluted with the highest PCB residue level of 150,000 ng/g. In addition, Minjiang Estuary (985.2 ng/g) and Taihu Lake (631 ng/g) had high levels of water pollution, while Pearl Estuary (635.7 ng/g) and Jiaozhou Bay (273.3 ng/g) had relatively high PCB levels in organisms. PCB pollution in soil was limited to a few special pollution areas with the highest PCB level of 4.5448 x 10(6) ng/g. Point source pollution was the common pattern of contamination, influenced primarily by local geographic, economic and historical factors. Analysis of PCB concentrations from the 1980s to 1990s shows an increasing trend, possibly due to the improper disposal of and leakage from PCB containers, chemical transfers, and the general rise of industrial pollution.

Animals↗

PubMed2005

The Src family kinases Hck and Fgr negatively regulate neutrophil and dendritic cell chemokine signaling via PIR-B.

In classical descriptions of leukocyte chemokine signaling, Src family kinases are thought to function in a positive fashion by coupling receptor associated Galpha subunits to downstream mitogen activated protein (MAP) kinase activation. However, neutrophils derived from hck-/-fgr-/- mice and dendritic cells (DCs) from fgr-/- animals manifested significantly higher intracellular signaling (Ca2+ flux, MAP kinase activation, actin polymerization) and functional responses (chemotaxis in vitro and migration in vivo) to a number of different chemokines. These kinases may mediate their effect through the inhibitory receptor PIR-B since neutrophils and DCs from pir-b-/- mice were also hyperresponsive to chemokine stimulation. In wild-type (wt) cells dephosphorylation of PIR-B was associated with maximal chemokine signaling, whereas in hck-/-fgr-/- cells PIR-B was unphosphorylated. These data support a model in which the Src family kinases Hck and Fgr function as negative regulators of myeloid cell chemokine signaling by maintaining the tonic phosphorylation of PIR-B.

Animals↗

PubMed2005

Distinction of pulmonary small cell carcinoma from poorly differentiated squamous cell carcinoma: an immunohistochemical approach.

Accurate morphologic distinction between small cell carcinoma and poorly differentiated squamous cell carcinoma has critical therapeutic significance, but can be limited by crush artifact, tumor necrosis, limited tumor representation, and overlapping morphologic features. We evaluated a panel of antibodies for their efficacy in distinguishing between these neoplasms. Formalin-fixed paraffin-embedded tissue sections of small cell carcinomas and poorly differentiated squamous cell carcinomas underwent immunohistochemical staining with antibodies to thyroid transcription factor-1, p63, high molecular weight keratin, and p16(INK4A). Of 28 small cell carcinomas, 26 (93%) small cell carcinomas showed diffuse moderate or strong staining for thyroid transcription factor-1 with no staining for high molecular weight keratin and p63. In contrast, 27/28 (96%) poorly differentiated squamous cell carcinomas manifested opposite immunoreactivities, with diffuse moderate or strong staining for high molecular weight keratin and p63, and no or minimal staining for thyroid transcription factor-1. In two additional cases originally interpreted as small cell carcinoma, high molecular weight keratin highlighted small numbers of neoplastic large cells, leading to reclassification as combined small cell and non-small cell carcinomas. p16(INK4A) expression varied widely in poorly differentiated squamous cell carcinomas, but was consistently moderate or strong and diffuse in small cell carcinomas, and proved helpful in the two thyroid transcription factor-1-negative small cell carcinomas. This study demonstrates that a panel consisting of antibodies to thyroid transcription factor-1, p63, high molecular weight keratin, and p16(INK4A) is highly effective for distinguishing between small cell carcinoma and poorly differentiated squamous cell carcinoma. This panel also facilitates diagnosis of combined small cell and non-small cell carcinomas.

Carcinoma, Small Cell↗

PubMed2005

Airborne emissions of mercury from municipal solid waste. I: new measurements from six operating landfills in Florida.

Mercury-bearing material enters municipal landfills from a wide array of sources, including fluorescent lights, batteries, electrical switches, thermometers, and general waste; however, the fate of mercury (Hg) in landfills has not been widely studied. Using automated flux chambers and downwind atmospheric sampling, we quantified the primary pathways of Hg vapor releases to the atmosphere at six municipal landfill operations in Florida. These pathways included landfill gas (LFG) releases from active vent systems, passive emissions from landfill surface covers, and emissions from daily activities at each working face (WF). We spiked the WF at two sites with known Hg sources; these were readily detected downwind, and were used to test our emission modeling approaches. Gaseous elemental mercury (Hg(O)) was released to the atmosphere at readily detectable rates from all sources measured; rates ranged from approximately 1-10 ng m(-2) hr(-1) over aged landfill cover, from approximately 8-20 mg/hr from LFG flares (LFG included Hg(O) at microg/m3 concentrations), and from approximately 200-400 mg/hr at the WF. These fluxes exceed our earlier published estimates. Attempts to identify specific Hg sources in excavated and sorted waste indicated few readily identifiable sources; because of effective mixing and diffusion of Hg(O), the entire waste mass acts as a source. We estimate that atmospheric Hg releases from municipal landfill operations in the state of Florida are on the order of 10-50 kg/yr, substantially larger than our original estimates, but still a small fraction of current overall anthropogenic losses.

Air Pollutants↗

PubMed2005

Airborne emissions of mercury from municipal solid waste. II: potential losses of airborne mercury before landfill.

Waste distribution and compaction at the working face of municipal waste landfills releases mercury vapor (Hg(o)) to the atmosphere, as does the flaring of landfill gas. Waste storage and processing before its addition to the landfill also has the potential to release Hg(o) to the air if it is initially present or formed by chemical reduction of Hg(II) to Hg(o) within collected waste. We measured the release of Hg vapor to the atmosphere during dumpster and transfer station activities and waste storage before landfilling at a municipal landfill operation in central Florida. We also quantified the potential contribution of specific Hg-bearing wastes, including mercury (Hg) thermometers and fluorescent bulbs, and searched for primary Hg sources in sorted wastes at three different landfills. Surprisingly large fluxes were estimated for Hg losses at transfer facilities (approximately 100 mg/hr) and from dumpsters in the field (approximately 30 mg/hr for 1000 dumpsters), suggesting that Hg emissions occurring before landfilling may constitute a significant fraction of the total emission from the disposal/landfill cycle and a need for more measurements on these sources. Reducing conditions of landfill burial were obviously not needed to generate strong Hg(o) signals, indicating that much of the Hg was already present in a metallic (Hg(o)) form. Attempts to identify specific Hg sources in excavated and sorted waste indicated few readily identifiable sources; because of effective mixing and diffusion of Hg(o), the entire waste mass acts as a source. Broken fluorescent bulbs and thermometers in dumpsters emitted Hg(o) at 10 to >100 microg/hr and continued to act as near constant sources for several days.

Air Pollutants↗

PubMed2005

NestinnegCD24low/- population from fetal Nestin-EGFP transgenic mice enriches the pancreatic endocrine progenitor cells.

OBJECTIVES: To identify whether Nestin-positve cells or Nestin-negative cells in pancreas enrich potential pancreatic stem/progenitor cells. METHODS: We generated transgenic mice carrying enhanced green fluorescent protein (EGFP) under the control of the nestin second-intronic enhancer and subsequently divided their embryonic pancreatic cells into different subpopulations according to the expression of EGFP and CD24 and characterized these subpopulations by in vitro culture. RESULTS: The EGFP expression correlated well with that of endogenous Nestin. Only the NestinCD24 subpopulation was able to proliferate and generate immature islet-like cell clusters in long-term culture. Immature islet-like cell clusters could be induced to differentiate into insulin-, glucagon-, and somatostatin-positive cells. CONCLUSIONS: Pancreatic endocrine stem/progenitor cells are enriched in the NestinCD24 population of embryonic pancreas.

Animals↗

PubMed2005

Microembolic signal characterization using adaptive chirplet expansion.

The adaptive chirplet expansion (ACE) is proposed to characterize high-intensity, transient signals from circulating microemboli. The nonnegative adaptive spectrogram based on the ACE gives a compact representation of the microembolic signal (MES) in joint-time, frequency domain. The mean instantaneous power (MIP) and mean instantaneous frequency (MIF) of MES are estimated from the adaptive spectrogram. Then, several important characteristics of MES, such as embolus-to-blood ratio (EBR), half width maximum (HWM), and embolic signal onset (ESO), are computed from the MIP, and the frequency modulation is examined in the MIF. To validate the new method, we improved the simulation model of the audio Doppler ultrasound signal. Some MESs together with a Doppler ultrasound signal from carotid blood flow are simulated in the simulation study. As a comparison, the adaptive Gabor expansion (AGE) also is implemented on these simulated signals. The experimental results of the simulation study show that the new method, based on the ACE, outperforms the AGE-based method in MES characterization. The consistent conclusion has been confirmed by the clinical study on some clinical MESs.

Algorithms↗

PubMed2005

Doppler ultrasound spectral enhancement using the Gabor transform-based spectral subtraction.

Most of the important clinical indices of blood flow are estimated from the spectrograms of Doppler ultrasound (US) signals. Any noise may degrade the readability of the spectrogram and the precision of the clinical indiCes, so the spectral enhancement plays an important role in Doppler US signal processing. A new Doppler US spectral enhancement method is proposed in this paper and implemented in three main steps: the Gabor transform is used to compute the Gabor coefficients of a Doppler US signal, the spectral subtraction is performed on the magnitude of the Gabor coefficients, and the Gabor expansion with the spectral subtracted Gabor coefficients is used to reconstruct the denoised Doppler US signal. The different analysis and synthesis windows are examined in the Gabor transform and expansion. The signal-to-noise ratio (SNR) improvement together with the overall enhancement of spectrograms are examined on the simulated Doppler US signals from a femoral artery. The results show the denoising method based on the orthogonal-like Gabor expansion achieves the best denoising performance. The experiments on some clinical Doppler US signals from umbilical arteries confirm the superior denoising performance of the new method.

Algorithms↗

PubMed2005

Analysis of human serum immunoglobulin G against O-acetyl-positive and O-acetyl-negative serogroup W135 meningococcal capsular polysaccharide.

The capsular polysaccharide of Neisseria meningitidis serogroup W135 is expressed in both O-acetyl-positive (OA+) and O-acetyl-negative (OA-) forms. This study investigates the impact of OA status (OA+ versus OA-) on serological measurements of anti-W135 immunoglobulin G (IgG) antibodies in immunized adults. W135-specific serum antibody assignments were made for 28 postimmunization sera from adults by enzyme-linked immunosorbent assay using the meningococcal standard reference serum CDC1992. The established IgG concentration in micrograms per milliliter ([IgG]microg/ml) for CDC1992 against OA+ antigen (16.2 microg/ml) was used as a reference to assign a concentration of 10.13 microg/ml IgG against OA- antigen by cross-standardization. Overall, the IgG assignments for these sera were higher against OA+ antigen (geometric mean concentration [GMC] = 7.16 microg/ml) than against OA- antigen (GMC = 2.84 microg/ml). However, seven sera showed higher specific [IgG]microg/ml values against the OA+ antigen than against the OA- antigen. These sera were also distinguished by the inability of fluid-phase OA- antigen to compete for antibody binding to OA+ solid-phase antigen. Although there was no overall difference in functional activity measured by complement-mediated serum bactericidal assay (SBA) against OA+ and OA- target bacteria (geometric mean titers of 9,642 and 9,045, respectively), three serum specimens showed a large difference in SBA antibody titers against OA+ versus OA- W135 target bacteria, which may reflect different epitope specificities for these sera. Our data indicate that, for some sera, the agreement in anti-OA+ versus anti-OA- W135 IgG assignments is serum specific and does not reflect the functional (killing) activity in vitro.

Acetylation↗

PubMed2005

Investigations into microsporidian methionine aminopeptidase type 2: a therapeutic target for microsporidiosis.

The Microsporidia have been reported to cause a wide range of clinical diseases particularly in patients that are immunosuppressed. They can infect virtually any organ system and cases of gastrointestinal infection, encephalitis, ocular infection, sinusitis, myositis and disseminated infection are well described in the literature. While benzimidazoles such as albendazole are active against many species of Microsporidia, these drugs do not have significant activity against Enterocytozoon bieneusi. Fumagillin, ovalicin and their analogues have been demonstrated to have antimicrosporidial activity in vitro and in animal models of microsporidiosis. Fumagillin has also been demonstrated to have efficacy in human infections due to E. bieneusi. Fumagillin is an irreversible inhibitor of methionine aminopeptidase type 2 (MetAP2). Homology cloning employing the polymerase chain reaction was used to identify the MetAP2 gene from the human pathogenic microsporidia Encephalitozoon cuniculi, Encephalitozoon hellem, Encephalitozoon intestinalis, Brachiola algerae and E. bieneusi. The full-length MetAP2 coding sequence was obtained for all of the Encephalitozoonidae. Recombinant E. cuniculi MetAP2 was produced in baculovirus and purified using chromatographic techniques. The in vitro activity and effect of the inhibitors bestatin and TNP-470 on this recombinant microsporidian MetAP2 was characterized. An in silico model of E. cuniculi MetAP2 was developed based on crystallographic data on human MetAP2. These reagents provide new tools for the development of in vitro assay systems to screen candidate compounds for use as new therapeutic agents for the treatment of microsporidiosis.

Amino Acid Sequence↗

PubMed2005

Altered expression of TFF-1 and CES-2 in Barrett's Esophagus and associated adenocarcinomas.

Identification of biomarkers to recognize individuals with Barrett's esophagus (BE) predisposed to develop malignancy is currently a pressing issue. We utilized gene expression profiling to compare molecular signatures of normal esophagus and stomach, BE, and adenocarcinoma (AC) to identify such potential biomarkers. Over 22,000 genes were analyzed by oligonucleotide microarrays on 38 unique RNA Unsupervised and supervised clusterings were performed on a subset of 2849 genes that varied most significantly across the specimens. Immunohistochemistry (IHC) for two of the significantly differentially expressed gene products was performed on tissue microarrays. Unsupervised clustering identified two discernable molecular BE profiles, one of which was similar to normal gastric tissue ("BE1"), and another that was shared by several of the AC specimens ("BE2"). The BE1 profile included expression of several genes that have been described as tumor-suppressor genes, most notably trefoil factor 1 (TFF-1). The BE2 profile included expression of genes previously found overexpressed in cancers, such as carboxylesterase-2 (CES-2). IHC demonstrated the loss of TFF-1 late in the progression of BE to AC. It also revealed CES-2 as being upregulated in AC documented to have arisen in the presence of BE. These potential biomarkers, as well as the relative expression of genes from BE1 versus those from BE2, may be validated in the future to aid in risk stratification and guide treatment protocols in patients with BE and associated AC.

Adenocarcinoma↗

PubMed2005

Application of 23Na MRI to monitor chemotherapeutic response in RIF-1 tumors.

Effects of an alkylating anticancer drug, cyclophosphamide (Cp), on 23Na signal intensity (23Na SI) and water apparent diffusion coefficient (ADC) were examined in subcutaneously-implanted radiation-induced fibrosarcoma (RIF-1) tumors by 23Na and 1H magnetic resonance imaging (MRI). MRI experiments were performed on untreated control (n = 5) and Cp-treated (n = 6) C3H mice, once before Cp injection (300 mg/kg) then daily for 3 days after treatment. Tumor volumes were significantly lower in treated animals 2 and 3 days posttreatment. At the same time points, in vivo MRI experiments showed an increase in both 23Na SI and water ADC in treated tumors, whereas control tumors did not show any significant changes. The correlation between 23Na SI and water ADC changes was dramatically increased in the Cp-treated group, suggesting that the observed increases in 23Na SI and water ADC were caused by the same mechanism. Histologic sections showed decreased cell density in the regions of increased 23Na and water ADC SI. Destructive chemical analysis showed that Cp treatment increased the relative extracellular space and tumor [Na+]. We conclude that the changes in water ADC and 23Na SI were largely due to an increase in extracellular space. 23Na MRI and 1H water ADC measurements may provide valuable noninvasive techniques for monitoring chemotherapeutic responses.

Animals↗