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Biomedical subjects

J Hu

Publications and source records attributed to J Hu.

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

Type II collagen and aggrecan mRNA expressions in rabbit condyle following disc displacement.

The aim of this investigation was to study the remodelling of cartilage in the mandibular condyle following disc displacement (DD) of the temporomandibular joint (TMJ). Forty adult Japanese white rabbits were used in this study. The right joints of 28 of the 40 rabbits had their discs surgically displaced. Four of the 28 were killed at 4 days or 1, 2, 4, 6, 8 and 12 weeks after surgery. The messenger RNA (mRNA) expression levels of aggrecan and type II collagen in cartilages were measured using in situ hybridization techniques. Results showed that aggrecan mRNA expression reduced in the first week after DD. The expression began to recover after 4 weeks and reached a normal level after 6 weeks. Type II collagen mRNA expression reduced from 4 weeks and the expression recovered after 8 weeks. This suggests that the chondrocyte reacting to the displacement of the TMJ disc, alters its matrix gene expression patterns and it is may be the cause of the shape changes of TMJ after DD.

Aggrecans↗
PubMed2005

Study of SARS transmission via liquid droplets in air.

Microscale liquid droplets could act as the SARS carriers in air when released from an infected person through breathing, coughing, or sneezing. In this study, a dynamic model has been built to quantitatively investigate the effect of the relative humidity on the transport of liquid-droplets in air using coupled mass transfer and momentum equations. Under higher relative humidity, the exhaled liquid droplets evaporate slowly. Larger droplets fall faster, which could reduce the probability of the droplets inhalation. This may be one of the most important factors that influence the SARS transmission in air.

Aerosols↗
PubMed2004

Effects of the silanized mica surface on protein crystallization.

A freshly cleaved mica surface silanized by 3-aminopropyl triethoxysilane is flat over a large area, displays a controlled degree of hydrophobicity and contains positive charges. In this paper, mica sheets silanized by this method have been used as crystallization surfaces for lysozyme, trichosanthin and three other proteins of unknown structure. Crystallization experiments have been carried out by the hanging-drop vapour-diffusion technique and the results indicate that the silanized mica surface can ameliorate the protein crystallization process considerably compared with a silanized glass cover slip control. For lysozyme on the silanized mica surface, the induction time required for crystal growth decreases markedly. For trichosanthin, the crystal size is obviously larger and the number of crystals grown is much lower. For the three proteins of unknown structure, the diffraction ability of the crystals is improved considerably.

Aluminum Silicates↗
PubMed2004

Proton source size measurements in the eA-->e'ppX reaction.

Two-proton correlations at small relative momentum q were studied in the eA(3He,4He,C,Fe)-->e(')ppX reaction at E(0)=4.46 GeV using the CLAS detector at Jefferson Lab. The enhancement of the correlation function at small q was found to be in accordance with theoretical expectations. Sizes of the emission region were extracted, and proved to be dependent on A and on the proton momentum. The size of the two-proton emission region for He was measured in eA reactions for the first time.

Journal Article↗
PubMed2004

Improved measurement of the K+-->pi+nunu; branching ratio.

An additional event near the upper kinematic limit for K+-->pi(+)nunu; has been observed by experiment E949 at Brookhaven National Laboratory. Combining previously reported and new data, the branching ratio is B(K+-->pi(+)nunu;)=(1.47(+1.30)(-0.89))x10(-10) based on three events observed in the pion momentum region 211<P<229 MeV/c. At the measured central value of the branching ratio, the additional event had a signal-to-background ratio of 0.9.

Journal Article↗
PubMed2004

Spiral scan long object reconstruction through PI line reconstruction.

The response of a point object in a cone beam (CB) spiral scan is analysed. Based on the result, a reconstruction algorithm for long object imaging in spiral scan cone beam CT is developed. A region-of-interest (ROI) of the long object is scanned with a detector smaller than the ROI, and a portion of it can be reconstructed without contamination from overlaying materials. The top and bottom surfaces of the ROI are defined by two sets of PI lines near the two ends of the spiral path. With this novel definition of the top and bottom ROI surfaces and through the use of projective geometry, it is straightforward to partition the cone beam image into regions corresponding to projections of the ROI, the overlaying objects or both. This also simplifies computation at source positions near the spiral ends, and makes it possible to reduce radiation exposure near the spiral ends substantially through simple hardware collimation. Simulation results to validate the algorithm are presented.

Algorithms↗
PubMed2004

Inheritance and molecular mapping of two fertility-restoring loci for Honglian gametophytic cytoplasmic male sterility in rice (Oryza sativaL.).

The Honglian cytoplasmic male sterility ( cms-HL) system, a novel type of gametophytic CMS in indica rice, is being used for the large-scale commercial production of hybrid rice in China. However, the genetic basis of fertility restoration ( Rf) in cms-HL remains unknown. Previous studies have shown that fertility restoration is controlled by a single locus located on chromosome 10, close to the loci Rf1 and Rf4, which respond to cms-BT and cms-WA, respectively. To determine if the Rf locus for cms-HL is different from these Rf loci and to establish fine-scale genetic and physical maps for map-based cloning of the Rf gene, high-resolution mapping of the Rf gene was carried out using RAPD and microsatellite markers in three BCF(1) populations. The results of the genetic linkage analysis indicated that two Rf loci respond to cms-HL, and that these are located in different regions of chromosome 10. One of these loci, Rf5, co-segregates with the SSR marker RM3150, and is flanked by RM1108 and RM5373, which are 0.9 cM and 1.3 cM away, respectively. Another Rf locus, designated as Rf6(t), co-segregates with RM5373, and is flanked by RM6737 and SBD07 at genetic distances of 0.4 cM. The results also demonstrated these loci are distinct from Rf1 and Rf4. A 105-kb BAC clone covering the Rf6(t) locus was obtained from a rice BAC library. The sequence of a 66-kb segment spanning the Rf6(t) locus was determined by a BLASTX search in the genomic sequence database established for the cultivar 93-11.

Cell Line↗
PubMed2004

Two-nucleon momentum distributions measured in 3He(e,e'pp)n.

We have measured the 3He(e,e'pp)n reaction at 2.2 GeV over a wide kinematic range. The kinetic energy distribution for "fast" nucleons (p>250 MeV/c) peaks where two nucleons each have 20% or less, and the third nucleon has most of the transferred energy. These fast pp and pn pairs are back to back with little momentum along the three-momentum transfer, indicating that they are spectators. Calculations by Sargsian and by Laget also indicate that we have measured distorted two-nucleon momentum distributions by striking one nucleon and detecting the spectator correlated pair.

Journal Article↗
PubMed2004

Observation of an exotic baryon with S=+1 in photoproduction from the proton.

The reaction gamma p-->pi(+)K(-)K(+)n was studied at Jefferson Laboratory using a tagged photon beam with an energy range of 3-5.47 GeV. A narrow baryon state with strangeness S=+1 and mass M=1555+/-10 MeV/c(2) was observed in the nK(+) invariant mass spectrum. The peak's width is consistent with the CLAS resolution (FWHM=26 MeV/c(2)), and its statistical significance is (7.8+/-1.0)sigma. A baryon with positive strangeness has exotic structure and cannot be described in the framework of the naive constituent quark model. The mass of the observed state is consistent with the mass predicted by the chiral soliton model for the Theta(+) baryon. In addition, the pK(+) invariant mass distribution was analyzed in the reaction gamma p-->K(-)K(+)p with high statistics in search of doubly charged exotic baryon states. No resonance structures were found in this spectrum.

Journal Article↗
PubMed2004

Oestrogen replacement therapy promotes bone healing around dental implants in osteoporotic rats.

The aim of this study was to investigate the effect of oestrogen replacement therapy on bone healing around titanium implants in osteoporotic rats. Sixty 32-week-old female SD rats were used in this study. Ovariectomies were performed in 40 rats, and other 20 rats had sham operation. Eighty-four days after surgery, osteoporotic changes in proximal tibiae were seen in four ovariectomized rats when compared with two sham-operated rats. Then pure titanium implants were placed in the bilateral proximal metaphyses of the tibiae of the remaining animals. Oestrogen replacement therapy was administrated in 18 ovariectomized rats after implantation. Nine rats from each group (ovariectomized, oestrogen-treated and sham-operated) were killed at 28 and 84 days after implantation surgery respectively, and the tibiae specimens were harvested and examined. Both at 28 and 84 days after implantation surgery, most bone histomorphometric indices in the oestrogen-treated group were significantly increased compared with those in the ovariectomized group (P < 0.05 or P < 0.01). Although the oestrogen-treated group showed lower trabecular bone volume at 28 days after implant surgery and lower mineralization rate at both the two time points than the sham-operated group, there were no significant differences in other bone histomorphometric indices between the oestrogen-treated group and the sham-operated group both at 24 and 84 days after implantation. The results of this study suggest that oestrogen replacement therapy may promote bone healing around titanium implants under osteoporotic state, and therefore it seemed to be beneficial to long-term success of dental implants in clinical postmenopausal patients.

Animals↗
PubMed2004

Mitochondrial DNA mutators.

In this article we review our current knowledge of the mechanisms by which point mutations arise in the mitochondrial DNA (mtDNA) of Saccharomyces cerevisiae and discuss to what extent these mechanisms operate in human mtDNA mutagenesis. The 3'-5' exonuclease proofreading activity of Pol gamma ensures accuracy of mtDNA replication in both yeast and humans, while the role of base excision repair in mtDNA error avoidance remains debated. The mitochondrial mismatch repair Msh1 protein, which removes transitions in yeast, is absent in humans, a particularity that might cause accumulation of transitions, while the most frequent substitution in yeast mtDNA is A:T to T:A transversion. Proofreading-deficient mutator human cell lines and knockin mice have been created. They will be useful for studying the mechanisms by which mtDNA mutations accumulate in diseases, ageing, malignancy and drug therapy.

Animals↗
PubMed2004

Class I topical corticosteroid use by psoriasis patients in an academic practice.

BACKGROUND: Psoriasis is a chronic skin disorder that can have a profound impact on the quality of life of patients. The treatment of psoriasis is complicated by the availability of numerous topical agents, systemic agents, and phototherapy. Of the topical preparations available, the ultra-high potency, or Class I steroids, have an important role in treating psoriasis. Their use is most appropriate for the treatment of plaques in regions excluding the face, axilla, groin and genitals. OBJECTIVE: The purpose of this study was to examine the prescribing patterns of Class I topical corticosteroids within a large academic dermatology practice for patients with all types of psoriasis. METHODS: A retrospective chart review of 650 patients with psoriasis from an academic dermatology practice was performed. Class I steroid use was defined as those patients who were observed to be currently using clobetasol propionate, halobetasol propionate, diflorasone, or augmented betamethasone dipropionate. RESULTS: A total of 79% of patients were prescribed topical steroids of any class while 46% of patients were prescribed a Class I steroid. In all, 58% of patients who received topical steroid therapy received a Class I agent; 11% of patients prescribed Class I steroids also received systemic therapy for their psoriasis. Conversely, 35% of patients who received systemic therapy were also receiving Class I topical therapy. DISCUSSION: In our department, Class I topical steroids are commonly used in the treatment of psoriasis. The superpotent topicals are often used as an adjunct to systemic therapy and will likely remain a mainstay of psoriasis therapy.

Administration, Topical↗
PubMed2004

Nanoscale analysis of biofunctional molecules and components.

In basic medical research, as well as in concrete clinical applications, the nanoscale analysis of biofunctional units is of strongly increasing relevance. Dedicated investigations on molecules, molecular composites or functional units can efficiently be performed ex or in situ by scanning probe methods and, namely, by scanning force microscopy. In the following investigations, the folding behavior of DNA is presented as an example of basic research in medicine. In contrast, the investigation of bioadsorption phenomena in systems on which apheresis therapies are based provides a real contribution to applied medicine.

Absorbable Implants↗
PubMed2004

Enzyme immobilization onto micro-sized modified PMMA microspheres.

Micro-sized acrolein-modified PMMA (poly[methyl methacrylate]) microspheres were used as the support for enzyme immobilization. The properties of immobilized enzyme as well as the immobilizing behavior were studied. The immobilized amount reached 76.8 mg.g(-1) support, which is relatively high compared with some analogous supports. The K(m) value was larger and the V(max) was smaller in the immobilized form than in the free form. Better resistance of the immobilized enzyme against the temperature, time and pH changes showed that the modified PMMA microspheres could be a good support for immobilization of pepsin.

Enzymes, Immobilized↗
PubMed2004

Removal of Cr(VI) by magnetite nanoparticle.

Magnetite nanoparticles were synthesized by sol-gel method. The highly crystalline nature of the magnetite structure with diameter of around 10 nm was characterized with transmission electron microscopy and X-ray diffractometry. The surface area was determined to be 198 m2/g. Batch experiments were carried out to determine the adsorption kinetics and mechanism of Cr(VI) by these magnetite nanoparticles. The Cr(VI) uptake was mainly governed by physico-chemical adsorption. The adsorption process was found to be pH and temperature dependent. The adsorption data fit well with the Freundlich isotherm equation. The Freundlich constants were calculated at different temperatures. The adsorption capacity increased with rising temperature. Preliminary results indicate that magnetite nanoparticles may be used as an adsorbent for removal of Cr(VI) from wastewater.

Adsorption↗
PubMed2003

Observation of an exotic S = +1 baryon in exclusive photoproduction from the deuteron.

In an exclusive measurement of the reaction gammad-->K(+)K(-)pn, a narrow peak that can be attributed to an exotic baryon with strangeness S=+1 is seen in the K(+)n invariant mass spectrum. The peak is at 1.542+/-0.005 GeV/c(2) with a measured width of 0.021 GeV/c(2) FWHM, which is largely determined by experimental mass resolution. The statistical significance of the peak is (5.2+/-0.6)sigma. The mass and width of the observed peak are consistent with recent reports of a narrow S=+1 baryon by other experimental groups.

Journal Article↗
PubMed2003

Measurement of the proton spin structure function g1(x,Q2) for Q2 from 0.15 to 1.6 GeV2 with CLAS.

Double-polarization asymmetries for inclusive ep scattering were measured at Jefferson Lab using 2.6 and 4.3 GeV longitudinally polarized electrons incident on a longitudinally polarized NH3 target in the CLAS detector. The polarized structure function g(1)(x,Q2) was extracted throughout the nucleon resonance region and into the deep inelastic regime, for Q(2)=0.15-1.64 GeV2. The contributions to the first moment Gamma(1)(Q2)= integral g(1)(x,Q2) dx were determined up to Q(2)=1.2 GeV2. Using a parametrization for g(1) in the unmeasured low x regions, the complete first moment was estimated over this Q2 region. A rapid change in Gamma(1) is observed for Q2<1 GeV2, with a sign change near Q(2)=0.3 GeV2, indicating dominant contributions from the resonance region. At Q(2)=1.2 GeV2 our data are below the perturbative QCD evolved scaling value.

Journal Article↗