PubMed Health⌕ Search

Biomedical subjects

Yong Yang

Publications and source records attributed to Yong Yang.

At least 91 records · Page 5Linked to original sources
PubMed2005

Spectroscopic characterization of Au3+ biosorption by waste biomass of Saccharomyces cerevisiae.

Some spectroscopic characteristics of Au3+ biosorption by waste biomass of Saccharomyces cerevisiae have been reported in this paper. The effect of temperature on the correlation parameters of chemical kinetics and thermodynamics of the binding reaction was investigated by using AAS. XRD diffraction pattern of gold-loaded biomass revealed that the Au3+ bound on the cell wall of the biomass had been reduced into gold particle. FTIR spectrophotometry on blank and gold-loaded biomass demonstrated that active groups such as the hydroxyl group of saccharides, and the carboxylate anion of amino-acid residues, from the peptidoglycan layer on the cell wall seem to be the sites for the Au3+ binding, and the free aldehyde group of the hemiacetalic hydroxyl group from reducing sugars, i.e. the hydrolysates of the polysaccharides on the peptidoglycan layer, serving as the electron donor, in situ reduced the Au3+ to Au0. XPS and IR characterizations of the interaction between glucose and Au3+ further supported that the reduction of Au3+ to Au0 can directly occur at the aldehyde group of the reducing sugars.

Adsorption↗
PubMed2005

The psoriasis disability index in Chinese patients: contribution of clinical and psychological variables.

OBJECTIVES: To provide a description of medical and psychological aspects of Chinese psoriasis patients, and to examine the specific contribution of demographic, medical and psychological variables to the Psoriasis Disability Index. METHODS: Ninety-three Chinese psoriasis patients underwent a clinical assessment using the Psoriasis Area and Severity Index (PASI) and completed a questionnaire that included questions on demographic and medical data, the Hospital Anxiety and Depression Scale (HADS) and the Psoriasis Disability Index (PDI). RESULTS: Psoriasis patients with cosmetic involvement had higher levels of anxiety and depression and higher disability scores than those without cosmetic involvement. Thirty-four per cent of the patients reported a significant level of anxiety (HADS-anx. > 11). The clinical severity of psoriasis was not associated with psychological and PDI scores. Multiple regression analysis indicated that psychological variables were associated with PDI scores, and explained 30% of the variance. However, demographic and psoriasis severity variables explained only 6% of the variance. CONCLUSION: Psoriasis patients suffer from anxiety and depression. Psychological factors are much stronger determinants of the PDI than demographic, disease related variables. Clinical management of the disease should consider both clinical and psychological factors.

Adaptation, Psychological↗
PubMed2005

Towards biologically conformal radiation therapy (BCRT): selective IMRT dose escalation under the guidance of spatial biology distribution.

It is well known that the spatial biology distribution (e.g., clonogen density, radiosensitivity, tumor proliferation rate, functional importance) in most tumors and sensitive structures is heterogeneous. Recent progress in biological imaging is making the mapping of this distribution increasingly possible. The purpose of this work is to establish a theoretical framework to quantitatively incorporate the spatial biology data into intensity modulated radiation therapy (IMRT) inverse planning. In order to implement this, we first derive a general formula for determining the desired dose to each tumor voxel for a known biology distribution of the tumor based on a linear-quadratic model. The desired target dose distribution is then used as the prescription for inverse planning. An objective function with the voxel-dependent prescription is constructed with incorporation of the nonuniform dose prescription. The functional unit density distribution in a sensitive structure is also considered phenomenologically when constructing the objective function. Two cases with different hypothetical biology distributions are used to illustrate the new inverse planning formalism. For comparison, treatments with a few uniform dose prescriptions and a simultaneous integrated boost are also planned. The biological indices, tumor control probability (TCP) and normal tissue complication probability (NTCP), are calculated for both types of plans and the superiority of the proposed technique over the conventional dose escalation scheme is demonstrated. Our calculations revealed that it is technically feasible to produce deliberately nonuniform dose distributions with consideration of biological information. Compared with the conventional dose escalation schemes, the new technique is capable of generating biologically conformal IMRT plans that significantly improve the TCP while reducing or keeping the NTCPs at their current levels. Biologically conformal radiation therapy (BCRT) incorporates patient-specific biological information and provides an outstanding opportunity for us to truly individualize radiation treatment. The proposed formalism lays a technical foundation for BCRT and allows us to maximally exploit the technical capacity of IMRT to more intelligently escalate the radiation dose.

Dose-Response Relationship, Radiation↗
PubMed2005

Optimization of radiotherapy dose-time fractionation with consideration of tumor specific biology.

The "four Rs" of radiobiology play an important role in the design of radiation therapy treatment protocol. The purpose of this work is to explore their influence on external beam radiotherapy for fast and slowly proliferating tumors and develop an optimization framework for tumor-biology specific dose-time-fractionation scheme. The linear quadratic model is used to describe radiation response of tumor, in which the time dependence of sublethal damage repair and the redistribution and reoxygenation effects are included. The optimum radiotherapeutic strategy is defined as the treatment scheme that maximizes tumor biologically effective dose (BED) while keeping normal tissue BED constant. The influence of different model parameters on total dose, overall treatment time, fraction size, and intervals is also studied. The results showed that, for fast proliferating tumors, the optimum overall time is similar to the assumed kickoff time T(k) and almost independent of interval patterns. Significant increase in tumor control can be achieved using accelerated schemes for the tumors with doubling time smaller than 3 days, but little is gained for those with doubling time greater than 5 days. The incomplete repair of normal tissues between two consecutive fractions in standard fractionation has almost no influence on the fractional doses, even for the hyperfractionation with an interval time of 8 h. However, when the resensitization effect is included, the fractional doses at the beginning and end of each irradiated week become obviously higher than others in the optimum scheme and the hyperfractionation scheme has little advantage over the standard or hypofractionation one. For slowly proliferating tumors, provided that the alpha/beta ratio of the tumor is comparable to that of the normal tissues, a hypofractionation is more favorable. The overall treatment time should be larger than a minimum, which is predominantly determined by the resensitization time. The proposed technique provides a useful tool to systematically optimize radiotherapy for fast and slow proliferating tumors and sheds important insight into the complex problem of dose-time fractionation.

Biophysical Phenomena↗
PubMed2005

Template guided self-assembling two-dimensional array of Au@SiO2 core-shell nanoparticles for room-temperature single electron transistors.

The composite nanoparticles of a gold core capped by a SiO2 shell with well-controlled thickness have been synthesized and fabricated into two-dimensional array on silicon surface by a simple self-assembly method combined with an AFM nanolithography technique. Current-voltage measurements of the Au@SiO2 composite nanoparticles (shell thickness of 6 nm) show a well-pronounced Coulomb staircase with a period of 300 mV at room temperature, demonstrating single electron transistor behavior. The step width of the Coulomb staircase can be tuned by controlling the thickness of SiO2 shell. The tunable single electron tunneling properties make the 2D array of Au@SiO2 composite nanoparticles an ideal candidate for planar single electron transistor devices.

Colloids↗
PubMed2005

[Clinical investigation in the expression of matrix metalloproteinase 2 mRNA in the hyperplastic scar in burn patients].

OBJECTIVE: To investigate the dynamic expression of matrix metalloproteinase 2 in the hyperplastic scar in burn patients. METHODS: Twenty-three pieces of hyperplastic scar tissue samples were harvested from the patients with deep partial thickness burn wound during the early, middle and late periods after natural wound healing. In situ hybridization technique and positive cell percentage counting were employed to determine the expression and the distribution of MMP-2 mRNA in the scar tissue from different periods with that of the middle period as the control. RESULTS: MMP-2 mRNA was mainly expressed in the fibroblasts in scar tissue. The positive percentage of MMP-2 in early period was 13.9 +/- 3.6%, and it increased thereafter, till it reached 68.7 +/- 5.2% in the middle period. However, it declined to 2.0 +/- 0.9% in the late period. CONCLUSION: MMP-2 might be closely related to the process of scar tissue remodeling.

Adult↗
PubMed2005

[The expression of p73 and c-fos protein in hemangioma and its significance].

OBJECTIVE: To investigate the expression of p73 and c-fos protein and its significance in the development of children hemangioma. METHODS: The quantitative expressions of p73 and c-fos protein in hemangioma and normal skin were detected by immunohistochemistry. RESULTS: The expressions of p73 and c-fos protein were strong in proliferative hemangioma while they were very weak in involutional hemangioma and normal skin. There were significant differences between the proliferative and involutional hemangioma or the normal skin in the expressions of p73 and c-fos (P < 0.01). No statistical significances of p73 or c-fos P73 expressions were observed between involutional hemangioma and normal skin (P > 0.05). CONCLUSIONS: P73 and c-fos may play an important role in the development and involution of skin hemangioma.

Child↗
PubMed2005

[Identification and marker-assisted selection of two major quantitative genes controlling rice sheath blight resistance in backcross generations].

We constructed an F2 clonal population of intercross,Teqing/Lemont, and identified two quantitative trait loci (QTLs) contributing to rice sheath blight resistance on chromosome 9 and 11. The two QTLs were qSB-9 and qSB-11, respectively. From the population, three clonal lines were selected by markers' band types on both sides of these two QTLs, qSB-9 and qSB-11. Two were double-susceptible parent with homozygous susceptible alleles of these two loci,and the other was named as double-resistant parent,of which these two loci were all homozygous resistant alleles. These parents were separately backcrossed to recurrent parents, Teqing or Lemont. From BC2F1, marker-assisted selection was conducted in each proceeding generation and all back-crossed plants in BC2F1 and BC4F1 were inoculated by short toothpicks incubated with a strain, RH-9 of the fungus for identification of the resistance. Results suggested that these two QTLs were selected effectively in each backcross generation and their positions were also verified in identification of resistance to rice sheath blight. In seedling nursery of BC3F2 population, plants were selected through marker-assisted selection, and were separately mixed as homozygous lines of double-susceptible alleles on the background of Teqing, double-susceptible and double-resistant on the background of Lemont. The homozygous lines and their recurrent parents were simultaneously planted on experiment fields of Agriculture Collage of Yangzhou University and Lixiahe District Institute of Agricultural Science. The inoculation was performed by a random-block test with two replicates at each site. The results indicated that 1) The difference of sheath blight disease development was highly significant among materials under the same genetic background,and the order of disease seriousness among different homozygous lines were: double-susceptible line on the background of Lemont > double-susceptible line on the background of Teqing > Lemont > Teqing > double-resistant line on the background of Lemont; 2) When the resistant allele of qSB-9 or qSB-11 solely existed in a plant, its disease rating was reduced about 1.2 score, and 2.0 score when they simultaneously existed on the background of Lemont; 3) No significant interaction between the two QTLs controlling sheath blight resistance and environments was found. These studies have laid a strong groundwork in operation and application, of these QTLs contributing to rice sheath blight resistance.

Alleles↗
PubMed2005

Facial fat volume in HIV-infected patients with lipoatrophy.

BACKGROUND: The volume and anatomical distribution of facial fat depletion in HIV related lipoatrophy have not been properly quantified. We aimed to determine the extent and distribution of facial fat loss in HIV-infected patients with lipoatrophy and whether this differs from wasting. DESIGN: We studied HIV-infected patients with clinically defined moderate to severe lipoatrophy without wasting (n = 15), clinically defined wasting (> 10% weight loss and recent opportunistic infection) with no previous reported lipodystrophy (n = 15), and controls without lipodystrophy or wasting (n = 15). Facial MRI scans were performed, and areas of fat were manually traced bilaterally in all individual image slices and summed to calculate volume in anatomically defined regions of interest. RESULTS: Patients with lipoatrophy had lower fat volumes in the temporal region (8.9 +/- 9.4 vs 20.5 +/- 7.2 ml; P < 0.001), cheek region (25.6 +/- 24.9 vs 55.5 +/- 15.0 ml; P < 0.001), periorbital region (1.9 +/- 1.0 vs 2.7 +/- 1.0 ml; P = 0.09) and buccal fat pad (13.4 +/- 9.4 vs 21.8 +/- 9.8 ml; P = 0.030) compared with controls. Patients with wasting had temporal, cheek, periorbital and buccal fat pad volumes (10.4 +/- 6.7 ml, 34.0 +/- 14.8 ml, 1.4 +/- 1.1 ml and 13.1 +/- 4.6 ml respectively) that were lower than controls (all P < 0.01) but similar to lipoatrophy patients (all P > 0.5). CONCLUSIONS: Facial fat depletion in lipoatrophy is substantial (approximately 50% volume loss) and involves superficial and deep fat (buccal fat pad). The distribution and volume of fat change is similar to that seen in wasting. Given the extent of the changes, complete surgical correction is unlikely to be possible and hence emphasis should be placed on prevention of lipoatrophy [corrected]

Adipose Tissue↗
PubMed2005

Size distribution of the secondary organic aerosol particles from the photooxidation of toluene.

In a smog chamber, the photooxidation of toluene was initiated by hydroxyl radical (OH*) under different experimental conditions. The size distribution of secondary organic aerosol(SOA) particles from the above reaction was measured using aerodynamic particle sizer spectrometer. It was found from our experimental results that the number of SOA particles increased with increasing the concentration of toluene. As the reaction time prolonged, the sum of SOA particles was also increased. After a reaction time of 130 min, the concentration of secondary organic aerosol particles would be kept constant at 2300 particles/cm3. Increasing illumination power of blacklamps could significantly induce a higher concentration of secondary organic aerosol particle. The density of SOA particles would also be increased with increasing concentration of CH3 ONO, however, it would be decreased as soon as the concentration of CH3 ONO was larger than 225.2 ppm. Nitrogen oxide with initial concentration higher than 30.1 ppm was also found to have little effect on the formation of secondary organic aerosol.

Aerosols↗
PubMed2004

Clinical knowledge-based inverse treatment planning.

Clinical IMRT treatment plans are currently made using dose-based optimization algorithms, which do not consider the nonlinear dose-volume effects for tumours and normal structures. The choice of structure specific importance factors represents an additional degree of freedom of the system and makes rigorous optimization intractable. The purpose of this work is to circumvent the two problems by developing a biologically more sensible yet clinically practical inverse planning framework. To implement this, the dose-volume status of a structure was characterized by using the effective volume in the voxel domain. A new objective function was constructed with the incorporation of the volumetric information of the system so that the figure of merit of a given IMRT plan depends not only on the dose deviation from the desired distribution but also the dose-volume status of the involved organs. The conventional importance factor of an organ was written into a product of two components: (i) a generic importance that parametrizes the relative importance of the organs in the ideal situation when the goals for all the organs are met; (ii) a dose-dependent factor that quantifies our level of clinical/dosimetric satisfaction for a given plan. The generic importance can be determined a priori, and in most circumstances, does not need adjustment, whereas the second one, which is responsible for the intractable behaviour of the trade-off seen in conventional inverse planning, was determined automatically. An inverse planning module based on the proposed formalism was implemented and applied to a prostate case and a head-neck case. A comparison with the conventional inverse planning technique indicated that, for the same target dose coverage, the critical structure sparing was substantially improved for both cases. The incorporation of clinical knowledge allows us to obtain better IMRT plans and makes it possible to auto-select the importance factors, greatly facilitating the inverse planning process. The new formalism proposed also reveals the relationship between different inverse planning schemes and gives important insight into the problem of therapeutic plan optimization. In particular, we show that the EUD-based optimization is a special case of the general inverse planning formalism described in this paper.

Algorithms↗
PubMed2004

Simple synthesis route to monodispersed SBA-15 silica rods.

A simple, flexible, reproducible, high-yielding (ca. 100%) synthesis of hexagonally facetted SBA-15 straight rods with uniform sizes (ca. 1.5 x 0.4 mum) under static conditions without using inorganic salts is provided. This method affords rodlike particles with temperature-dependent pore sizes ranging from 5.8 to 12.5 nm but with similar external dimensions. This work shows that in order to prepare short monodispersed SBA-15 rods, (i) the absence of stirring is essential, (ii) the temperature of the first stage should not exceed 60 degrees C, and (iii) addition of inorganic salts is not required.

Journal Article↗
PubMed2004

Effects of iptakalim on rotenone-induced cytotoxicity and dopamine release from PC12 cells.

Parkinson's disease is characterized by an extensive loss of dopaminergic neurons in the substantia nigra pars compacta. The final common pathway in the demise of these cells may involve dopamine-dependent oxidative stress. Previous studies revealed a new neuronal protective role of ATP-sensitive potassium channel openers. But the exact mechanism is still unknown. In the present study, the neuroprotective effect of iptakalim, a novel ATP-sensitive potassium channel opener, was studied against rotenone-induced cytotoxicity in rat dopaminergic PC12 cells. Rotenone decreased cell viability significantly after 48 h exposure and induced dopamine release from PC12 cells concentration-dependently. Iptakalim significantly enhanced dopamine uptake and alleviated rotenone-induced PC12 cells death and reduced dopamine release induced by rotenone or GBR-12909, a classical dopamine transporter inhibitor. These results suggest that iptakalim may open mitochondrial K(ATP) channels to modulate dopamine transporter and reduce extracellular dopamine levels, thereby it protecting PC12 cells against rotenone-induced injury.

Adenosine Triphosphate↗
PubMed2004

Quantitative measurement of MLC leaf displacements using an electronic portal image device.

The success of an IMRT treatment relies on the positioning accuracy of the MLC (multileaf collimator) leaves for both step-and-shoot and dynamic deliveries. In practice, however, there exists no effective and quantitative means for routine MLC QA and this has become one of the bottleneck problems in IMRT implementation. In this work we present an electronic portal image device (EPID) based method for fast and accurate measurement of MLC leaf positions at arbitrary locations within the 40 cm x 40 cm radiation field. The new technique utilizes the fact that the integral signal in a small region of interest (ROI) is a sensitive and reliable indicator of the leaf displacement. In this approach, the integral signal at a ROI was expressed as a weighted sum of the contributions from the displacements of the leaf above the point and the adjacent leaves. The weighting factors or linear coefficients of the system equations were determined by fitting the integral signal data for a group of pre-designed MLC leaf sequences to the known leaf displacements that were intentionally introduced during the creation of the leaf sequences. Once the calibration is done, the system can be used for routine MLC leaf positioning QA to detect possible leaf errors. A series of tests was carried out to examine the functionality and accuracy of the technique. Our results show that the proposed technique is potentially superior to the conventional edge-detecting approach in two aspects: (i) it deals with the problem in a systematic approach and allows us to take into account the influence of the adjacent MLC leaves effectively; and (ii) it may improve the signal-to-noise ratio and is thus capable of quantitatively measuring extremely small leaf positional displacements. Our results indicate that the technique can detect a leaf positional error as small as 0.1 mm at an arbitrary point within the field in the absence of EPID set-up error and 0.3 mm when the uncertainty is considered. Given its simplicity, efficiency and accuracy, we believe that the technique is ideally suitable for routine MLC leaf positioning QA.

Algorithms↗
PubMed2004

Castleman's tumours and production of autoantibody in paraneoplastic pemphigus.

BACKGROUND: Paraneoplastic pemphigus is an autoimmune mucocutaneous disease associated with Castleman's tumours, which when surgically removed often result in great improvement of mucocutaneous lesions. An IgG autoantibody against epidermal proteins is often used as a diagnostic marker for disease. Our aim was to ascertain the role of Castleman's tumours in production of the autoantibody and pathogenesis of paraneoplastic pemphigus. METHODS: We enrolled seven patients with paraneoplastic pemphigus associated with Castleman's disease and assessed the effect of removal of tumours on mucocutaneous lesions in six individuals and on autoantibody titre with indirect immunofluorescence in four patients. We cultured tumour cells from one patient and assayed the secreted autoantibody. Finally, we characterised the gene sequence and expression of the variable region of the immunoglobulin heavy chain (IgV(H)) in tumour B cells from all patients by reverse transcription-PCR, DNA sequencing, and in-situ hybridisation. FINDINGS: Cutaneous lesions disappeared within 6-11 weeks after resection of tumours. Mucosal lesions also improved in this period, but lasted for 5-10 months overall. Autoantibody titre decreased and became undetectable within 5-9 weeks in three of four patients assessed. We identified secreted autoantibody, similar to that identified in patients' serum, in cultured tumour cells. The tumour B-cells of the seven patients shared and expressed two rearrangement patterns of complementarity determining region 3 (CDR3) of IgV(H). INTERPRETATION: Secreted autoantibody from Castleman's tumours, which reacts against epidermal proteins, could be an essential factor in the pathogenesis of paraneoplastic pemphigus. We noted clonal rearrangement, resulting in similar variable regions of IgV(H), in tumour B cells isolated from all seven patients. However, whether this pattern is associated with autoimmunity remains to be ascertained.

Adolescent↗
PubMed2004

In situ TA-MS study of the six-membered-ring-based growth of carbon nanotubes with benzene precursor.

By using the in situ thermal analysis-mass spectroscopic technique, combined with transmission electron microscopic characterization of the carbon nanotube (CNT) product, we have studied the chemical vapor deposition (CVD) growth of CNTs with Fe-Co/gamma-Al2O3 catalyst and benzene precursor in the range of room temperature to 700 degrees C. The growth process has been clearly illuminated, which starts from the reduction of catalyst around 645 degrees C followed by the dissociation of carbon-hydrogen bonds of benzene and the sequential growth of CNTs. A surprising fact is that no possible hydrocarbon species derived from benzene was detected, indicating that the carbon-carbon bond was not broken under our experimental conditions. All of the experimental results strongly reinforce the six-membered-ring-based growth model, and a schematic elucidation is presented accordingly. This in situ study not only reveals the unique and convincing information directly related to the growth mechanism from the involved chemistry, but also provides a powerful way to clarify the mechanism of CVD synthesis of CNTs with other precursors.

Journal Article↗