Biomedical subjects

Feng Huang

Publications and source records attributed to Feng Huang.

51 records · Page 3Linked to original sources

PubMed2004

Determining thickness independently from optical constants by use of ultrafast light.

We show that the application of ultrafast techniques, especially terahertz time-domain spectroscopy, allows simultaneous measurements of material thickness and optical constants from transmission measurements, by analyzing not only the phase difference between the main terahertz pulse through the medium but also the subsequent multireflection pulse (an echo) from the medium. Such a method provides a fast and precise characterization of the optical properties and can extract thickness information and hence other optical constants in a broad bandwidth. It may have applications in science and engineering such as in situ film thickness and quality monitoring, optical constants measurement, medical imaging, noninvasive detection, and remote sensing.

Journal Article↗

PubMed2004

Nanoparticles: strained and stiff.

Nanoparticles may contain unusual forms of structural disorder that can substantially modify materials properties and thus cannot solely be considered as small pieces of bulk material. We have developed a method to quantify intermediate-range order in 3.4-nanometer-diameter zinc sulfide nanoparticles and show that structural coherence is lost over distances beyond 2 nanometers. The zinc-sulfur Einstein vibration frequency in the nanoparticles is substantially higher than that in the bulk zinc sulfide, implying structural stiffening. This cannot be explained by the observed 1% radial compression and must be primarily due to inhomogeneous internal strain caused by competing relaxations from an irregular surface. The methods developed here are generally applicable to the characterization of nanoscale solids, many of which may exhibit complex disorder and strain.

Journal Article↗

PubMed2004

Analysis and simulation of the structure of nanoparticles that undergo a surface-driven structural transformation.

A room temperature solid-state structural transformation was observed in 3 nm ZnS nanoparticles in methanol following the addition of water (Zhang et al., Nature 424, 1025, 2003). Experimental wide angle x-ray scattering (WAXS), x-ray absorption near edge structure (XANES) and extended x-ray absorption fine structure (EXAFS) spectroscopy measurements show a large increase in crystallinity associated with water addition, in agreement with molecular dynamics (MD) predictions. Here we perform first-shell EXAFS and pair distribution function analysis and whole-nanoparticle calculations of WAXS, EXAFS and XANES to compare structural data with the MD predictions. The predicted WAXS patterns give excellent agreement with data, while the predicted EXAFS and XANES spectra give poor agreement. Relative to WAXS, XANES and EXAFS spectra contain additional structural information related to the distribution of disorder. The discrepancy between the x-ray diffraction and x-ray absorption results indicates that structural disorder is partitioned between interior and surface regions more strongly than predicted in the MD simulations.

Journal Article↗

PubMed2004

Reversible, surface-controlled structure transformation in nanoparticles induced by an aggregation state.

The structure of 3 nm ZnS nanoparticles differs from that of bulk ZnS and is shown to vary with the particle aggregation state. Dispersed or weakly aggregated nanoparticles in suspension have a more distorted internal structure than strongly aggregated nanoparticles. Reversible switching between distorted and crystalline structures can be induced by changing the aggregation state via slow drying and ultrasonic agitation. The transformation was analyzed using pair distribution function data from wide angle x-ray diffraction and the aggregation state monitored via small angle x-ray scattering. Molecular modeling provides insight into particle-particle interactions that induce the structural changes. The reversible nature also implies a low activation energy of nanoparticle transformation and indicates that distorted nanoparticles are not trapped in a metastable state.

Journal Article↗

PubMed2004

[Comparison of genetic polymorphism of cytochrome CYP2C19 between men and women in Chinese population].

AIM: To assess the effect of gender on genetic polymorphism of cytochrome CYP2C19 in Chinese population. METHODS: The genetic polymorphism of 140 healthy Chinese were analysed by PCR-RFLP (restriction fragment length polymorphism). RESULTS: Of 52 genotyped male subjects, 23 (44.23%) were homozygous for wildtype (wt/wt), 6 (11.54%) were homozygous for CYP2C19 m1 (m1/m1), and 23 (44.23%) were heterozygous for CYP2C19 m1 or CYP2C19 m2 (wt/m1 or wt/m2); and among the 88 genotyped female subjects, 31 (35.23%) were homozygous for wildtype (wt/wt), 13 (14.82%) were homozygous for CYP2C19 m1 (m1/m1), and 44 (50.0%) were heterozygous for CYP2C19 m1 or CYP2C19 m2 (wt/m1 or wt/m2); no homozygous genotype for CYP2C19 m2 (m2/m2) was found in the study. CONCLUSION: There is no statistical difference in ocurance of wt/wt and m1/m1 between in male and in female, so gender have no significant effect on genetic polymorphism of cytochrome CYP2C19.

Adolescent↗

PubMed2004

[Intel random number generator-based true random number generator].

OBJECTIVE: To establish a true random number generator on the basis of certain Intel chips. METHODS: The random numbers were acquired by programming using Microsoft Visual C++ 6.0 via register reading from the random number generator (RNG) unit of an Intel 815 chipset-based computer with Intel Security Driver (ISD). RESULT: We tested the generator with 500 random numbers in NIST FIPS 140-1 and X(2) R-Squared test, and the result showed that the random number it generated satisfied the demand of independence and uniform distribution. We also compared the random numbers generated by Intel RNG-based true random number generator and those from the random number table statistically, by using the same amount of 7500 random numbers in the same value domain, which showed that the SD, SE and CV of Intel RNG-based random number generator were less than those of the random number table. The result of u test of two CVs revealed no significant difference between the two methods. CONCLUSION: Intel RNG-based random number generator can produce high-quality random numbers with good independence and uniform distribution, and solves some problems with random number table in acquisition of the random numbers.

Algorithms↗

PubMed2004

[Inhibition of proliferation and influence of proto-oncogenes expression by matrine in C6 cell].

OBJECTIVE: This study were designed to investigate the inhibition of matrine on C6 glioma cell line and its mechanism. METHODS: MTT was used to measure the levels of the proliferation of C6 cultured with matrine in different concentrations. The effects of matrine on cell cycle of C6 were observed by FCM. The expression of proto-oncogenes C-myc was measured by RT-PCR. RESULT: The proliferation of C6 was obviously inhibited by matrine in a dose dependent manner. The inhibitory rate came to 53.8% +/- 5.6%, when cultured with matrine at 0.20 g/L. The outcome of FCM showed that the proportion of G0/G1 phase cells was decreased obviously, the proportion of S phase cells was reduced when cultured with matrine at 0.20 g/L in 3 days. The outcome of RT-PCR showed that the expression of proto-oncogene C-myc was notably decreased when the dose of matrine was increased. CONCLUSION: Matrine can inhibit the proliferation of C6 and inhibit the expression of proto-oncogenc C-myc.

Alkaloids↗

PubMed2004

[Effect of ginsenoside Rg1 on the influence of neprilysin expression induced by LPS in BT325 cell line].

OBJECTIVE: To investigate the effect of ginsenoside Rg1 on the influence of neprilysin expression induced by LPS in BT325 cell line. METHOD: MTT was used to measure the levels of the survival rate of BT325 cultured with ginsenoside Rg1 and LPS in different concentrations. The expression of NEP was measured by RT-PCR. RESULT: The survival rate of BT325 was obviously inhibited by LPS, and the expression of NEP was decreased. The survival rate of BT325 was obviously raised by ginsenoside Rg1, and the expression of NEP was increased. CONCLUSION: LPS can cause cell damage, and decrease the expression of NEP. Ginsenoside Rg1 can exert neuroprotective properties which protects BT325 cell line from the cell toxicity of LPS.

Cell Line, Tumor↗

PubMed2003

Water-driven structure transformation in nanoparticles at room temperature.

The thermodynamic behaviour of small particles differs from that of the bulk material by the free energy term gammaA--the product of the surface (or interfacial) free energy and the surface (or interfacial) area. When the surfaces of polymorphs of the same material possess different interfacial free energies, a change in phase stability can occur with decreasing particle size. Here we describe a nanoparticle system that undergoes structural changes in response to changes in the surface environment rather than particle size. ZnS nanoparticles (average diameter 3 nm) were synthesized in methanol and found to exhibit a reversible structural transformation accompanying methanol desorption, indicating that the particles readily adopt minimum energy structural configurations. The binding of water to the as-formed particles at room temperature leads to a dramatic structural modification, significantly reducing distortions of the surface and interior to generate a structure close to that of sphalerite (tetrahedrally coordinated cubic ZnS). These findings suggest a route for post-synthesis control of nanoparticle structure and the potential use of the nanoparticle structural state as an environmental sensor. Furthermore, the results imply that the structure and reactivity of nanoparticles at planetary surfaces, in interplanetary dust and in the biosphere, will depend on both particle size and the nature of the surrounding molecules.

Journal Article↗

PubMed2003

New therapies for ankylosing spondylitis: etanercept, thalidomide, and pamidronate.

Ankylosing spondylitis (AS) is the most common of a group of diseases called seronegative spondyloarthropathies. This group of diseases shares common demographic, clinical, and genetic features. This article reviews the rationale, clinical efficacy, and safety reports of etanercept, thalidomide, and pamidronate in the treatment of patients who have AS.

Anti-Inflammatory Agents↗

PubMed2003

Juvenile spondyloarthropathies: the Chinese experience.

The data presented here show that in Chinese juvenile-onset AS patients, their clinical features were similar to those reported by Burgos-Vargas and other researchers looking at other ethnic groups. For most JSpA patients, its relation to HLA-B27, basic clinical expression, anatomic substrate, histopathologic nature of the lesion, and response to treatment are the same or similar to those of adult-onset SpA patients. Current treatments provide relief but do not alter the natural course of the disease. New treatments that target immune responses and cellular inflammatory processes, which play a part in the pathogenesis of SpA, are under investigation. TNF-alpha has been identified as a predominant proinflammatory cytokine in synovial tissue of patients who have SpA. Clinical, histologic, and immunohistochemical findings of studies of anti-TNF-alpha antibody therapy in adult SpA patients suggest the possibility of altering the progression of disease coincident with clinical improvement. These findings in adult SpA patients suggest that anti-TNF-alpha therapy might confer similar benefits to JSpA patients.

Asian People↗

PubMed2003

[Drug-resistant proteins in breast cancer: recent progress in multidrug resistance].

Breast cancer resistance protein (BCRP) is a new multidrug resistance-related transmembrane transporter. BCRP is a 655-amino acid, 72.6 kDa protein, localized in the plasma membrane. As a member of the ATP-binding cassette family of drug transporters, BCRP has only one ATP-binding cassette and six putative transmembrane domains, suggesting that BCRP is a half-transporter, which may function as a homodimer or heterodimer. The BCRP-overexpressing tumor cells are resistant to mitoxantrone, adriamycin, daunorubicin, etoposide, topotecan and irinotecan, but lack resistance to paclitaxel and vincristine. Fumitremorgin C and GF120918 can effectively reverse multidrug resistance in BCRP-overexpressing tumor cells, associated with an increase in drug accumulation. In normal human tissues, low to high expressions of BCRP in placental syncytiotrophoblasts, in the epithelium of the small intestine and colon, in the liver canalicular membrane, in ducts of the breast, in endothelium of the blood vessel and in stem cells were reported. This expression profile allows speculation on a role of BCRP in protection of the fetus and in the regulation of transport of chemicals through the epithelium of the gastrointestinal tract. BCRP can account for chemoresistance of some clinical cancers such as acute myeloid leukemia, non-small cell lung cancer,and breast cancer.

ATP Binding Cassette Transporter, Subfamily G, Mem↗

PubMed2003

Thalidomide for severe refractory ankylosing spondylitis: a 6-month open-label trial.

OBJECTIVE: To examine the efficacy of thalidomide in the treatment of active ankylosing spondylitis (AS) refractory to conventional therapies. METHODS: In a 6-month open-label trial, we studied 13 men with different subtypes of active AS: 3 juvenile AS, 9 adult AS, and one AS with psoriasis. All patients were resistant to conventional nonbiologic therapies including nonsteroidal antiinflammatory drugs, sulfasalazine, and methotrexate. After 3 months' observation on a preexisting regimen, oral thalidomide was added, starting at 100 mg/day for 1 week, then 200 mg/day for another 23 weeks. Outcome measures included the Bath AS Disease Activity Index (BASDAI), Functional Index (BASFI), Global Index (BAS-G), IgA, C-reactive protein (CRP), and eosinophil sedimentation rate (ESR). Response to treatment was defined following the Ankylosing Spondylitis Assessment criteria. RESULTS: Three patients withdrew due to rash. Two patients were lost to followup due to lack of efficacy. Eight patients completed the trial. Four patients attained > 50% improvement (2 juvenile AS, 1 peripheral AS, and 1 psoriatic arthritis). Four patients attained > 20% improvement (2 axial and 2 peripheral AS). Total response rate accordingly was 80% (8/10). Mean BASDAI improved significantly from baseline to Week 24 (4.97 vs 3.1; p = 0.0156). Mean BASFI improved from baseline to Week 24 (5.24 vs 3.06; p = 0.0078), and BAS-G from 6.02 to 3.21 (p = 0.0078). Significant laboratory improvements were found in ESR (from 69.5 to 34.2 mm/h; p = 0.0156), but not CRP (from 6.08 to 3.01 mg/dl; p = 0.078) or IgA (from 496 to 505 mg/dl; p = 0.375). Dry mouth, constipation, and dizziness were common, but no severe adverse events were found. CONCLUSION: Thalidomide is a promising treatment for patients with active AS who are resistant to conventional therapies other than biologics.

Adult↗

PubMed2002

One-year open-label trial of thalidomide in ankylosing spondylitis.

OBJECTIVES: To test in a large open study whether thalidomide is potentially useful in treating ankylosing spondylitis, and to see if thalidomide induces any change in expression of genes in peripheral blood mononuclear cells (PBMC). METHODS: Thirty male patients with treatment-refractory ankylosing spondylitis were recruited into a 12-month open study using thalidomide at a dosage of 200 mg/day. Seven indices were measured as primary outcome measures, and 6 other indices as secondary outcome measures. Transcripts in the PBMC of some of these patients were first screened with microarray, and then measured with reverse transcriptase-polymerase chain reaction. RESULTS: Twenty-six patients completed the study. Of these, 80% showed a >20% improvement in 4 of 7 primary indices. Sharp declines in several parameters were noticed at 3-6 months. Nine patients became pain-free. There was also a statistically significant decrease in tumor necrosis factor alpha transcripts in the PBMC. CONCLUSION: Thalidomide is a reasonably promising drug in treatment-resistant ankylosing spondylitis.

Adult↗

PubMed2002

Clues to pathogenesis of spondyloarthropathy derived from synovial fluid mononuclear cell gene expression profiles.

OBJECTIVE: To use gene expression profiles of spondyloarthropathy (SpA) synovial fluid mononuclear cells (SFMC) to determine if there are transcripts that support the unfolded protein response (UPR) hypothesis, and to identify which cytokines/chemokines are being expressed and which cell fractions are involved. METHODS: Gene expression profiles were generated by microarray screening of SFMC of 5 patients with SpA, 5 patients with rheumatoid arthritis (RA), and peripheral blood mononuclear cells (PBMC) of 6 controls. Results were validated by reverse transcription polymerase chain reaction using samples from a larger panel of subjects. RESULTS: The repertoires of proinflammatory cytokines/chemokines expressed by SpA and RA SFMC were very similar: monocyte chemotractant protein 1 (MCP-1), interleukin 8 (IL-8), IL-1beta, endothelial-monocyte activating polypeptide II, interferon-gamma, and tumor necrosis factor-alpha. MCP-1 was highly expressed in SpA SFMC. There was enhanced expression of immunoglobulin heavy chain binding protein (BiP) in SpA, which is compatible with the UPR hypothesis. BiP was most highly expressed in the adherent fraction of SpA SFMC. CONCLUSION: Previous data postulating UPR in SpA are based on in vitro experiments with transfected cell lines. Our patient derived data suggest that it also occurs in vivo in the macrophages of SpA joints.

Adolescent↗