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Biomedical subjects

Min Hu

Publications and source records attributed to Min Hu.

At least 91 records · Page 5Linked to original sources
PubMed2004

Rapid lengthening of rabbit mandibular ramus by using nitinol spring: a preliminary study.

Nitinol is well known for its shape memory and superelasticity, which means it can return to its original shape from large deflections and produce moderate forces in the process. Based on these characteristics, the authors attempted to use an internal Nitinol spring for automatic lengthening of mandibular ramus. Twenty adult white rabbits underwent transverse osteotomy in unilateral mandibular ramus to remove a 15.0 mm condylar segment and L-osteotomy in remnant ramus to create a vascularized transport disc. The S-shaped Nitinol spring, with two ends bent as perpendicular underprops, was constricted and secured across the transverse gap of L osteotomy by the underprops. Six animals were killed 6 days after operation for observation of bone transport rate. Other surviving rabbits were killed 8 weeks later for morphologic and histologic examination. Mechanical testing revealed moderate output of tensile elasticity by constricted spring on shape recovery in 37 degrees C. Rapid lengthening of mandibular ramus, more than 9.0 mm in 5 to 6 days, and new bone formation in 8 weeks were found. The radiograph and histologic appearance of regenerated bone was similar to those seen with traditional distraction osteogenesis. This preliminary study demonstrates the possibility of spring-mediated rapid mandibular lengthening across an osteotomy. However, the method needs additional scientific investigation for its clinical feasibility.

Alloys↗
PubMed2004

Matching T-cell receptors identified in renal biopsies and urine at the time of acute rejection in pediatric renal transplant patients.

Urinary monitoring of kidney allograft function has been used for many years. More recently, molecular identification of cytotoxic T-cell products has been used as a diagnostic tool in acute rejection. Monitoring of T-cell infiltrates by analysis of the T-cell receptor (TcR) gene usage has been performed on biopsies with acute and chronic rejection, but not on urine samples. The aim of this study was to identify and compare TRBV gene usage assessing the CDR3 (Complementarity Determining Region 3) length distribution and sequence in urine and biopsies of pediatric renal allograft patients at the time of acute rejection and compare them with peripheral blood. We studied four pediatric renal transplant recipients with acute cellular rejection. We identified restricted and matched TRBV CDR3 spectratypes with overexpressed TRBV families and show identical, clonally expanded TRBV CDR3 sequences in all four patients present in the urine and renal allograft. We demonstrate that urinary monitoring can detect graft-infiltrating lymphocytes in acute rejection and may have a role in the monitoring of renal transplants.

Acute Disease↗
PubMed2004

[Biomechanical study of open bite treatment with tip forward bend].

OBJECTIVE: To verify whether it is effective to treat open bite cases with tip-forward bend. METHODS: Three-dimensional finite element (TDFE) models of the lower left central incisor and first molar were set up by means of CT. Stress distribution in root, PDL and alveolar bone, and the tendency of the tooth movement were obtained by calculation under different orthodontic forces. RESULTS: (1) The molar model revealed that the tensile stress concentration was at the distal cervix and the compressive stress concentration at mesial cervix. (2) The incisor model showed that the tensile stress was concentrated at apical tip and the compressive stress concentration was at the lingual side of the cervix. (3) The incisor had the tendency to elongate and move lingually. The molar tended to tip mesially and buccally. CONCLUSIONS: Arch wire with tip forward bend depends on the elongation and lingual movement of anterior teeth to treat open bite, but the anchorage molar will incline mesially further, which is not consistent with the mechanism to treat open bite.

Biomechanical Phenomena↗
PubMed2004

[Influence of terrestrial nutrient input on biogenic production of dimethylsulfide in Quingdao coastal water].

Nearshore water is one of the most important emission area of dimethylsulfide(DMS), at the same time, nearshore water is highly disturbed by human activities. The objectives of this study were to investigate the DMS concentration of coastal water and try to analyze the factors governing its distribution. Four situ investigations were made in the coastal water of Qingdao, which is located at west coast of Yellow Sea. DMS concentrations of surface water showed a clear seasonal variation with peak values during the summer. Spatial and temporal distributions of DMS in three studied areas(havey polluted area, light polluted area, and clean area) were irregular, but when the concentrations of DMS were moralized to chlorophyll a as a measure of phytoplankton biomass, there was significant difference of DMS/Chl a among the three areas, with the nutrient concentration improved, the DMS/Chl a decreased. And there was the positive relation between transparency and DMS/Chl a, especially in summer.

Biomass↗
PubMed2004

[Dimethylsulfide emission in Qingdao near-shore waters and atmospheric dimethylsulfide concentration variation].

To investigate the emission of dimethylsulfide in near-shore waters seriously disturbed by human activities in China, using the solid absorption-desorption and cryogenic preconcentration method, sampling and analysis of seawater and atmospheric DMS in Qingdao near-shore waters were carried out during 2001-2002. The results showed that the spatial distribution and seasonal variation of seawater DMS concentrations and sea-air fluxes were evident. In summer, the average of seawater DMS concentrations was highest, amounting to 1169.47 ng x L(-1) and lowest in spring, only 226.99 ng x L(-1). The obvious concentration gradient in estuarine, landscape and Olympic Game areas were observed in summer, but in spring and autumn is not so evident. Sea-air flux of DMS was mainly determined by seawater concentration, therefore the sea-air flux coincided with seawater concentration. Average atmospheric DMS concentration was higher in the summer (256.44 ng x m(-3)) and lower in the autumn (195.64 ng x m(-3)). The diurnal variation of atmospheric DMS was discussed in paper.

Air Pollutants↗
PubMed2004

Characterization of fine organic particulate matter from Chinese cooking.

PM2.5 samples were collected by a three-stage cascade impactor at two kinds of Chinese restaurants to characterize fine organic particulate matter from Chinese cooking sources. Major individual organic compounds have been quantified by GC/MS, including series of alkanes, n-alkanoic acids, n-alkanals, alkan-2-ones and PAHs. Alkanes and ketones make up a significant fraction of particle-phase organic compounds, ranging from C11 to C26, and C9 to C19, respectively. In addition, other organic compound classes have been identified, such as alkanols, esters, furans, lactones, amides, and nitriles. The mass concentrations of fine particles, alkanes, n-alkanoic acids and PAHs in air emitted from the Uigur style cooking are hundreds times higher than ambient PM2.5 in Beijing.

Air Pollution, Indoor↗
PubMed2004

EphA2 induction of fibronectin creates a permissive microenvironment for malignant cells.

Normal and metastatic cells continuously exchange information with the surrounding tissue environment, and this communication governs many aspects of cell behavior. In particular, the physical placement or adhesions of cells within their environment are increasingly understood to facilitate this communication. Classically, cell-cell and cell-extracellular matrix adhesions have been viewed as separable events that are independently controlled. This simple view is changing, as evidence emerges of coordinated regulation of cellular adhesions. Here, we show that the EphA2 tyrosine kinase, which is overexpressed in many aggressive cancers, regulates a fine balance of cell-cell and cell-extracellular matrix adhesions in epithelial cells. EphA2 selectively inhibits cell-cell adhesions by increasing cell attachment and up-regulating the extracellular matrix protein fibronectin. We also show that fibronectin can contribute to important aspects of malignant character. Antibody-based targeting of EphA2 inhibits malignant cell growth by decreasing fibronectin and thereby inducing apoptotic death. Our findings strengthen a concept that cancer progression is regulated by a bidirectional communication between tumor cells and their surrounding microenvironment.

Antibodies↗
PubMed2004

[Determination of politary organic compounds in atmospheric fine particulate matter in Beijing City].

A determination method was developed for the quantification of polar organic compounds in atmospheric fine particles in Beijing City by GC-MS. The optimally reactive conditions of two derivative methods were set up. The related coefficients (R2) of standard curves were 0.995-1.000. The precise of the GC-MS was 1%-10%, and the quantified detection limits ranged from 0.1 to 4.0 ng x microL(-1) depending on the various standard compounds. The percent relative standard deviation of standards and atmospheric samples were 3%-20% and 3%-17%, respectively. The methods were applied for Beijing fine particle samples in summer, fall, and winter in 2002. Total 42 polar organic compounds were identified and quantified, including 30 n-aliphatic and n-alkenoic acid species, 5 aliphatic dicarboxylic acid species, 3 monosaccharide anhydrides, 3 steroids, and benzoic acid. The sources of these compounds were discussed.

Air Pollutants↗
PubMed2004

[Determination of water soluble organic acids in PM2.5 of atmosphere in Beijing City].

Ten water soluble organic acids in PM2.5 of atmosphere in Beijing were determined by capillary electrophoresis, including low molecular weight dicarboxylic acids, aldehyde acids, ketoacids and methanesulfonic acid. The quantified detection limits ranged from 110 to 280 microg/L (extract). The precise of peak area was between 1.7% and 6.0%, and the correlation coefficients of standard curve were 0.995-0.999. The average total concentrations of the ten organic acids in summer, fall and winter were 721 ng/m3, 362 ng/m3 and 325 ng/m3, respectively, which were comparable with some foreign big cities. Oxalic acid was the most abundant species. By exploring seasonal variations of the acids, their source characteristics were simply discussed.

Air Pollutants↗
PubMed2004

[Spatial distribution of seawater dimethylsulfide in winter of Jiulong Jiang Estuary].

Cruise investigation of dimethylsulfide (DMS) emission in estuarine areas, heavily disturbed by human activities, was carried out in the winter of 2001 in Jiulong Jiang Estuary. The concentrations of chlorophyll, salinity and nutrients showed evidently spatial distribution in Jiulong Jiang Estuary, so did DMS concentrations in surface water. The average of seawater DMS was 101.0 and 242.1 ng x L(-1) in river mouth area and gulf area, respectively. DMS concentrations decreased first with the increase of seawater salinity and then increased. The highest DMS concentration occurred at river plume front of maximum turbidity zone of the estuary.

Air Pollutants↗
PubMed2003

Vibrational response of nanorods to ultrafast laser induced heating: theoretical and experimental analysis.

In this paper, we elucidate the vibrational response of cylindrical nanorods to ultrafast laser-induced heating. A theoretical analysis of the expected behavior is first presented. This analysis predicts that both extensional and breathing vibrational modes of the rods should be excited by laser-induced heating. Analytical formulas are derived assuming that the heating/expansion process is instantaneous, and that the lengths of the rods are much greater than their radii. These results show that the breathing mode dominates the mechanical deformation of the rod. However, because the frequency of the extensional mode is much lower than that of the breathing mode, the extensional mode will dominate the response for a real experiment (a finite-time heating/expansion process). The results of this model are compared to data from transient absorption experiments performed on gold nanorods with average lengths between 30 and 110 nm. The transient absorption traces show pronounced modulations with periods between 40 and 120 ps, which are only observed when the probe laser is tuned to the longitudinal plasmon band. The measured periods are in good agreement with the expected values for the extensional modes of the rods. For rods wider than 20 nm, the breathing mode can also be observed and, again, the measured periods are in good agreement with the theoretical calculations. The breathing mode is not observed for thinner rods (<20 nm width) because, in this case, the period is comparable to the time scale for lattice heating.

Journal Article↗
PubMed2003

Differential EphA2 epitope display on normal versus malignant cells.

The EphA2 receptor tyrosine kinase is overexpressed in many different types of human cancers where it functions as a powerful oncoprotein. Dramatic changes in the subcellular localization and function of EphA2 have also been linked with cancer, and in particular, unstable cancer cell-cell contacts prevent EphA2 from stably binding its ligand on the surface of adjoining cells. This change is important in light of evidence that ligand binding causes EphA2 to transmit signals that negatively regulate tumor cell growth and invasiveness and also induce EphA2 degradation. On the basis of these properties, we have begun to target EphA2 on tumor cells using agonistic antibodies, which mimic the consequences of ligand binding. In our present study, we show that a subset of agonistic EphA2 antibodies selectively bind epitopes on malignant cells, which are not available on nontransformed epithelial cells. We also show that such epitopes arise from differential cell-cell adhesions and that the stable intercellular junctions of nontransformed epithelial cells occlude the binding site for ligand, as well as this subset of EphA2 antibodies. Finally, we demonstrate that antibody targeting of EphA2 decreases tumor cell growth as measured using xenograft tumor models and found that the mechanism of antibody action relates to EphA2 protein degradation in vivo. Taken together, these results suggest new opportunities for therapeutic targeting of the large number of different cancers that express EphA2 in a manner that could minimize potential toxicities to normal cells.

Animals↗
PubMed2003

Three-dimensional hyaluronic acid grafts promote healing and reduce scar formation in skin incision wounds.

Hyaluronic acid (HA) has been found to play important roles in tissue regeneration and wound-healing processes. Fetal tissue with a high concentration of HA heals rapidly without scarring. The present study employed HA formed into three-dimensional strands with or without keratinocytes to treat full-thickness skin incision wounds in rats. Wound closure rates of HA strand grafts both with and without keratinocytes were substantially enhanced. The closure times of both HA grafts were less than 1 day (average 16 h), about 1/7 that of the contralateral control incisions (114 h, p <.01). Average wound areas after 10 days were HA-only graft: 0.151 mm2 +/- 0.035; HA + cell grafts: 0.143 mm2 +/- 0.036 and controls: 14.434 mm2 +/- 1.175, experimental areas were 1% of the controls (p < 0.01). Transforming growth factor (TGF) beta1 measured by immunostaining was remarkably reduced in HA-treated wounds compared to the controls. In conclusion, HA grafts appeared to produce a fetal-like environment with reduced TGF-beta1, which is known to be elevated in incipient scars. The HA strands with or without cultured cells may potentially improve clinical wound healing as well as reduce scar formation.

Animals↗
PubMed2003

Macrolactonization via Ti(IV)-mediated epoxy-acid coupling: a total synthesis of (-)-dactylolide [and zampanolide].

A total synthesis of dactylolide (1) is described. The key feature involves the Ti(IV)-mediated coupling of structurally complex "Sharpless epoxides" and carboxylic acids in either an intramolecular (macrolactonization) or an intermolecular mode. Other notable aspects include a proton-catalyzed, cis-selective construction of the 4-methylenetetrahydropyran ring; a selective oxidation of an allylic alcohol in the presence of a 1,2-diol by an oxoammonium ion; an efficient ring-closing metathesis reaction of an in situ (bis-TMS) protected alpha,omega-diene-vic-diol; and an aluminum-mediated aza-aldol reaction of a primary amide to 1 to construct the acyclic carbinolamide in zampanolide.

Animals↗
PubMed2003

Lipid oxidation in corn oil-in-water emulsions stabilized by casein, whey protein isolate, and soy protein isolate.

Proteins can be used to produce cationic oil-in-water emulsion droplets at pH 3.0 that have high oxidative stability. This research investigated differences in the physical properties and oxidative stability of corn oil-in-water emulsions stabilized by casein, whey protein isolate (WPI), or soy protein isolate (SPI) at pH 3.0. Emulsions were prepared with 5% corn oil and 0.2-1.5% protein. Physically stable, monomodal emulsions were prepared with 1.5% casein, 1.0 or 1.5% SPI, and > or =0.5% WPI. The oxidative stability of the different protein-stabilized emulsions was in the order of casein > WPI > SPI as determined by monitoring both lipid hydroperoxide and headspace hexanal formation. The degree of positive charge on the protein-stabilized emulsion droplets was not the only factor involved in the inhibition of lipid oxidation because the charge of the emulsion droplets (WPI > casein > or = SPI) did not parallel oxidative stability. Other potential reasons for differences in oxidative stability of the protein-stabilized emulsions include differences in interfacial film thickness, protein chelating properties, and differences in free radical scavenging amino acids. This research shows that differences can be seen in the oxidative stability of protein-stabilized emulsions; however, further research is needed to determine the mechanisms for these differences.

Chemical Phenomena↗
PubMed2003

Impact of whey protein emulsifiers on the oxidative stability of salmon oil-in-water emulsions.

To obtain a better understanding of how the interfacial region of emulsion droplets influences lipid oxidation, the oxidative stability of salmon oil-in-water emulsions stabilized by whey protein isolate (WPI), sweet whey (SW), beta-lactoglobulin (beta-Lg), or alpha-lactalbumin (alpha-La) was evaluated. Studies on the influence of pH on lipid oxidation in WPI-stabilized emulsions showed that formation of lipid hydroperoxides and headspace propanal was much lower at pH values below the protein's isoelectric point (pI), at which the emulsion droplets were positively charged, compared to that at pH values above the pI, at which the emulsion droplets were negatively charged. This effect was likely due to the ability of positively charged emulsion droplets to repel cationic iron. In a comparison of lipid oxidation rates of WPI-, SW-, beta-Lg-, and alpha-La-stabilized emulsions at pH 3, the oxidative stability was in the order of beta-Lg > or = SW > alpha-La > or = WPI. The result indicated that it was possible to engineer emulsions with greater oxidative stability by using proteins as emulsifier, thereby reducing or eliminating the need for exogenous food antioxidants.

Drug Stability↗