Biomedical subjects

Q Kang

Publications and source records attributed to Q Kang.

17 recordsLinked to original sources

PubMed2005

Effects of sterilization on implant mechanical property and biocompatibility.

This article concisely reviews the effects of sterilization on the mechanical properties and surface chemistries of implantable biomaterials. This article also summarizes the biological effects of the sterilization-related changes in the implant. Because there are so many different types of implant materials currently in use (including metals, polymers, and diverse biological materials), the response of tissue to these different materials varies dramatically. This review further discusses the effects of sterilization on in vivo and in vitro tissue response specifically to implantable metals and polyethylene, with the possibility of future biocompatibility testing of the implants sterilized with supercritical phase carbon dioxide sterilization.

Biocompatible Materials↗

PubMed2004

Characterization of the distinct orthotopic bone-forming activity of 14 BMPs using recombinant adenovirus-mediated gene delivery.

Efficacious bone regeneration could revolutionize the clinical management of bone and musculoskeletal disorders. Although several bone morphogenetic proteins (BMPs) (mostly BMP-2 and BMP-7) have been shown to induce bone formation, it is unclear whether the currently used BMPs represent the most osteogenic ones. Until recently, comprehensive analysis of osteogenic activity of all BMPs has been hampered by the fact that recombinant proteins are either not biologically active or not available for all BMPs. In this study, we used recombinant adenoviruses expressing the 14 types of BMPs (AdBMPs), and demonstrated that, in addition to currently used BMP-2 and BMP-7, BMP-6 and BMP-9 effectively induced orthotopic ossification when either AdBMP-transduced osteoblast progenitors or the viral vectors were injected into the quadriceps of athymic mice. Radiographic and histological evaluation demonstrated that BMP-6 and BMP-9 induced the most robust and mature ossification at multiple time points. BMP-3, a negative regulator of bone formation, was shown to effectively inhibit orthotopic ossification induced by BMP-2, BMP-6, and BMP-7. However, BMP-3 exerted no inhibitory effect on BMP-9-induced bone formation, suggesting that BMP-9 may transduce osteogenic signaling differently. Our findings suggest that BMP-6 and BMP-9 may represent more effective osteogenic factors for bone regeneration.

Adenoviridae↗

PubMed2002

The mass transfer process and the growth rate of protein crystals.

In this paper, protein crystal growth is studied by a Mach-Zehnder interferometer and an image process system. The interference fringe images are recorded during the crystallization of tetragonal hen egg white lysozyme crystal. Concentration distributions of the protein solution are given from the interference fringe images recorded by the Mach-Zehnder interferometer with a real time servo system of a four-step phase shift. The mass transfer flux and the crystal growth rates are obtained from the concentration distribution. The results show that the observed rates are in accordance with those demonstrated by measurements of the experimental images; therefore the method for determining growth rate by the diffusion process is reasonable.

Crystallization↗

PubMed2001

Metalloprotease-disintegrin ADAM 12 interacts with alpha-actinin-1.

ADAM 12, a member of the ADAM family of proteins (containing A Disintegrin And Metalloprotease domain), has been implicated in differentiation and fusion of myoblasts. While the extracellular domain of ADAM 12 contains an active metalloprotease and a region involved in cell adhesion, the function of the cytoplasmic tail of ADAM 12 has been less clear. Here we show that the cytoplasmic domain of ADAM 12 interacts in vitro and in vivo with alpha-actinin-1, an actin-binding and cross-linking protein. Green fluorescent protein fused to ADAM 12 cytoplasmic domain co-localizes with alpha-actinin-1-containing actin stress fibres in C2C12 cells. The interaction between ADAM 12 and alpha-actinin-1 is direct and involves the 58-amino acid C-terminal fragment of ADAM 12 and the 27 kDa N-terminal domain of alpha-actinin-1. Consistently, expression of the 27 kDa fragment of alpha-actinin-1 in C2C12 cells using a mitochondrial targeting system results in recruitment of the co-expressed ADAM 12 cytoplasmic domain to the mitochondrial surface. Moreover, alpha-actinin-1 co-purifies with a transmembrane, His6-tagged form of ADAM 12 expressed in C2C12 myoblasts, indicating that the transmembrane ADAM 12 forms a complex with alpha-actinin-1 in vivo. These results indicate that the actin cytoskeleton may play a critical role in ADAM 12-mediated cell-cell adhesion or cell signalling during myoblast differentiation and fusion.

ADAM Proteins↗

PubMed2001

Direct interaction between the cytoplasmic tail of ADAM 12 and the Src homology 3 domain of p85alpha activates phosphatidylinositol 3-kinase in C2C12 cells.

ADAM 12, a member of the ADAM family of transmembrane metalloprotease-disintegrins, has been implicated previously in the differentiation of skeletal myoblasts. In the present study, we show that the cytoplasmic tail of mouse ADAM 12 interacts in vitro and in vivo with the Src homology 3 domain of the p85alpha regulatory subunit of phosphatidylinositol (PI) 3-kinase. By site-directed mutagenesis, we have identified three p85alpha-binding sites in ADAM 12 involving PXXP motifs located at amino acids 825-828, 833-836, and 884-887. Using green fluorescent protein (GFP)-pleckstrin homology (PH) domain fusion protein as a probe for PI 3-kinase lipid products, we have further demonstrated that expression of ADAM 12 in C2C12 cells resulted in translocation of GFP-PH to the plasma membrane. This suggests that transmembrane ADAM 12, by providing docking sites for the Src homology 3 domain of p85alpha, activates PI 3-kinase by mediating its recruitment to the membrane. Because PI 3-kinase is critical for terminal differentiation of myoblasts, and because expression of ADAM 12 is up-regulated at the onset of the differentiation process, ADAM 12-mediated activation may constitute one of the regulatory mechanisms for PI 3-kinase during myoblast differentiation.

ADAM Proteins↗

PubMed2001

Interarticular bone tunnel healing.

PURPOSE: To evaluate the healing behavior of an interarticular bone tunnel exposed continuously to a synovial environment. TYPE OF STUDY: Experimental in vivo animal model. METHODS: Twenty-six adult rabbits had 3.2-mm diameter tunnels drilled in the femur and tibia of both hind-limb stifle joints parallel to but without violation of the native anterior cruciate ligament (ACL). The animals were euthanized at 1, 2, 4, and 12 weeks postoperatively. Decalcified sections were made of the bone tunnels and new bone formation was computer quantified using histomorphometric methods at each time interval. RESULTS: In this model, bone tunnel healing velocity was most rapid between 1 and 2 weeks after surgery. Both femoral and tibial interosseous tunnels showed substantial bone ingrowth (71% of bone tunnel volume) by 2 weeks postoperatively. The peripheral tunnel segment, that third of the tunnel furthest from the joint surface, healed rapidly and was 99% occluded with bone (99% confidence interval, 93.7% to 100%) at 2 weeks. Tunnel ingrowth was delayed and incomplete in the articular third of the tunnel, especially the femoral side. At 12 weeks, by volume, only 69.1% (99% confidence interval, 52.3% to 85.7%) of the interarticular third of the femoral tunnel was ingrown with new bone. Peripheral third bone tunnel healing was significantly greater than articular third tunnel healing at all time intervals; P <. 005 for the femoral and P <. 05 for the tibial tunnel. CONCLUSIONS: Interarticular bone tunnels heal from the outside in. At 12 weeks, bone healing was slower and incomplete in the articular segment of the tunnel, closest to the joint surface. The same biologic factors that impede intersubstance ACL healing may interfere with bone tunnel healing and be another cause of bone tunnel enlargement after ACL reconstruction.

Animals↗

PubMed2000

Metalloprotease-disintegrin ADAM 12 binds to the SH3 domain of Src and activates Src tyrosine kinase in C2C12 cells.

ADAM 12, a member of the ADAM (protein containing a disintegrin and metalloprotease) family of metalloprotease-disintegrins, has been implicated in the differentiation and fusion of skeletal myoblasts, and its expression is dramatically up-regulated in many cancer cells. While the extracellular portion of ADAM 12 contains an active metalloprotease and a cell-adhesion domain, the function of the cytoplasmic portion is much less clear. In this paper, we show that the cytoplasmic tail of ADAM 12 mediates interactions with the non-receptor protein tyrosine kinase Src. The interaction is direct, specific, and involves the N-terminal proline-rich region in the cytoplasmic tail of ADAM 12 and the Src homology 3 (SH3) domain of Src. ADAM 12 and Src co-immunoprecipitate from transfected C2C12 cells, suggesting that the two proteins form a complex in vivo. Co-expression of Src and ADAM 12, but not ADAM 9, in C2C12 cells results in activation of the recombinant Src. Moreover, endogenous ADAM 12 associates with and activates endogenous Src in differentiating C2C12 cells. These results indicate that ADAM 12 may mediate adhesion-induced signalling during myoblast differentiation.

ADAM Proteins↗

PubMed1999

Generation of an adenovirus vector lacking E1, e2a, E3, and all of E4 except open reading frame 3.

Toxicity and immunity associated with adenovirus backbone gene expression is an important hurdle to overcome for successful gene therapy. Recent efforts to improve adenovirus vectors for in vivo use have focused on the sequential deletion of essential early genes. Adenovirus vectors have been constructed with the E1 gene deleted and with this deletion in combination with an E2a, E2b, or E4 deletion. We report here a novel vector (Av4orf3nBg) lacking E1, E2a, and all of E4 except open reading frame 3 (ORF3) and expressing a beta-galactosidase reporter gene. This vector was generated by transfection of a plasmid carrying the full-length vector sequence into A30.S8 cells that express E1 and E2a but not E4. Production was subsequently performed in an E1-, E2a-, and E4-complementing cell line. We demonstrated with C57BL/6 mice that the Av4orf3nBg vector effected gene transfer with an efficiency comparable to that of the Av3nBg (wild-type E4) vector but that the former exhibited a higher level of beta-galactosidase expression. This observation suggests that E4 ORF3 alone is able to enhance RNA levels from the beta-galactosidase gene when the Rous sarcoma virus promoter is used to drive transgene expression in the mouse liver. In addition, we observed less liver toxicity in mice injected with the Av4orf3nBg vector than those injected with the Av3nBg vector at a comparable DNA copy number per cell. This study suggests that the additional deletion of E4 in an E1 and E2a deletion background may be beneficial in decreasing immunogenicity and improving safety and toxicity profiles, as well as increasing transgene capacity and expression for liver-directed gene therapy.

Adenovirus E1 Proteins↗

PubMed1998

Mechanical properties and bone densities of canine trabecular bone.

The purposes of this study were (1) to evaluate the mechanical properties of canine epiphyseal cancellous bones from adult canine femoral heads, femoral condyles, tibial plateau, and humeral heads, using indentation and compression tests, and (2) to measure bone densities (apparent density and ash density) of these cancellous bones so as to develop a normal data base of mechanical strength and bone density. The correlations between the two mechanical tests and between these tests and bone densities were also considered. The results showed all of the three mechanical parameters, ultimate load, stiffness, and ultimate strength, measured by the indentation test were higher than those measured by the compression test. Correlation analysis showed that the two sets of mechanical values correlated well (r=0.823-0.952, p<0.01). The apparent density and ash density correlated well with the mechanical parameters determined by the two types of mechanical tests (r=0.737-0.966, p<0.05).

Journal Article↗

PubMed1998

Morphological and mechanical study on the effects of experimentally induced inflammatory knee arthritis in rabbit long bones.

Inflammatory knee arthritis was induced by intraarticular injection of carrageenan twice a week for a total of 6 weeks in New Zealand White rabbits and the effects of the arthritis on the morphological and mechanical properties of the adjacent femur and tibia were evaluated 8 weeks after the first injection. Carrageenan-induced knee arthritis resulted in severe osteopenic changes and a dramatic decrease in bone strength of the entire ipsilateral femur and tibia, including the femoral head and distal tibia, but not the contralateral femur and tibia and the remote humerus. The osteoporotic changes of the adjacent bones of the inflammatory arthritic knee are the basis for the reduced mechanical strength of these bones. These findings may have clinical significance with regard to the mechanisms and consequences of osteoporotic changes in patients with rheumatoid arthritis.

Journal Article↗

PubMed1997

Mechanical properties of rat epiphyseal cancellous bones studied by indentation testing.

Twenty-six pairs of rat femoral heads, distal femurs, proximal tibiae, and humeral heads were tested using an indentation test with a flat-ended cylindrical indentor. A useful mechanical data set including ultimate load, stiffness, and ultimate strength has been generated. Differences were found between the cancellous bones at different locations. Good correlations have been obtained between indentation depth (at 50 N load) and ultimate strength (R=-0.937, p<0.05), which means that with an increase of ultimate strength the indentation depth or deformation decreased proportionally. Based on the experimental results and the comparison with other methods in the literature, the simplicity and usefulness of this indentation test to evaluate compressive mechanical properties of rat epiphyseal cancellous bone are apparent.

Journal Article↗

PubMed1997

Effects of multiple freezing-thawing cycles on ultimate indentation load and stiffness of bovine cancellous bone.

OBJECTIVE: To assess the effects of multiple freezing-thawing cycles on ultimate indentation load and stiffness of bovine tibial cancellous bone with regard to freezing conditions (saline solution or air) or methods of thawing (saline solution or air). SAMPLES: 4 tibias from 4 adult cows. PROCEDURE: The proximal portions of the tibias were sectioned to produce 20-mm-thick bone slices. Slices were subjected to 5 freezing-thawing cycles under 4 conditions: freezing with and without saline solution, then thawing in saline solution or exposed to the air. The mechanical properties of the bone slices before and after the treatments were measured, using an indentation test for comparison. Indentation testing was performed before and after freezing-thawing cycles to measure differences in mechanical parameters. RESULTS: Significant differences in mechanical parameters were not found for bone specimens frozen in saline solution and thawed in saline solution; frozen without saline solution and thawed in air; frozen in saline solution and thawed in air; or frozen without saline solution and thawed in saline solution. CONCLUSIONS: Multiple thawing-freezing cycles do not significantly affect the ultimate indentation load and stiffness of bovine tibial cancellous bone.

Animals↗

PubMed1996

Prevention of bacterial adherence to implant surfaces with a crosslinked albumin coating in vitro.

Titanium surfaces were coated with bovine serum albumin using carbodiimide, a crosslinking agent. The durability of the coated surfaces and the inhibitory effect of the albumin coating on bacterial adherence were tested in vitro for 20 consecutive days at 37 degrees C in phosphate buffered saline, with intermittent agitation. The results showed that only 10% of the coated bovine serum albumin decayed off the surface during the 20-day incubation period. The inhibition rate of the albumin coating on bacterial adherence remained high (greater than 8.5%) throughout the experiment. The results suggested potential use of this crosslinked albumin coating to reduce bacterial adherence and thus the subsequent possibility of prosthetic or implant infection in vivo.

Bacterial Adhesion↗

PubMed1996

Mechanical symmetry of rabbit bones studied by bending and indentation testing.

OBJECTIVE: To determine whether mechanical parameters of rabbit long bones are bilaterally symmetric. ANIMALS: Adult male New Zealand White rabbits. PROCEDURE: 17 pairs of femurs, tibias, and humeri were mechanically tested with 3-point bending (for diaphyseal bone) and indentation (for epiphyseal bone). RESULTS: Significant differences were not found between the right and left femur, tibia, or humerus for all bending parameters. Significant differences were not found between the right and left femoral, tibial, or humeral epiphyses for all indentation parameters. CONCLUSIONS: The results indicate mechanical symmetry of rabbit long bones in terms of mean value. The study also developed a normal comparable database for bending and indentation parameters of the rabbit femur, tibia, and humerus.

Animals↗

PubMed1995

Radiographic sizing for meniscal transplantation.

Allograft or synthetic meniscal replacement has the potential to delay the arthritic sequelae of the meniscectomized knee. Meniscal implants must, however, be side and size specific. A cadaveric study was performed in which medial and lateral menisci were painted with a radiopaque tantalum powder-cyanoacrylic mixture. Radiographs of this preparation demonstrated reproducible relationships between each meniscus and established bony landmarks. When corrected for magnification, meniscal size could be derived from plain films. Meniscal width equaled the distance (coronal) from the peak of the tibial eminence to the periphery of the tibial metaphysis on anteroposterior films. Meniscal length was measured from lateral radiographs. Medial meniscal length was 80%, and lateral meniscal length was 70% of the measured sagittal length of the tibial plateau. Measurement error averaged 7.8% by these parameters.

Arthritis↗

PubMed1995

[Nationwide survey of the distribution of human parasites in China--infection with parasite species in human population].

The infection rate of main species of parasites and their character by first nationwide survey of human parasites was made. The overall infection rate of human intestinal parasite and the infection rate of most species of parasites were higher in females than that in males. The infection rate according to the age group, the highest infection rate was found in the group aged 5-14 years. With regard to the relation between parasitic infections and occupations of the infected persons, the highest infection rates of Ascaris lumbricoides were exhibited in school children, of hookworm and Clonorchis sinensis were in halfpeasants and halfmerchant and vegetable grower; of Trichuris trichiura were in fishers, of Giardia lamblia, Entamoeba histolytica and Taenia were in herdsmen and halfherdsmen and halfpeasants. In this survey it is also shown that each nationality has their main species of parasites. The family clustering of some main parasites were proved by some province/autonomous region/municipality.

Adolescent↗

PubMed1989

Ten families of ankylosing spondylitis.

Twenty-two patients with ankylosing spondylitis (AS) from 10 families were studied with special attention to their clinical findings, HLA-B27 examinations and family histories. Results showed that HLA-B27 was positive in 19 and negative in 3. The hereditary relationship between ankylosing spondylitis and HLA-B27 in Chinese was similar to that in westerners. We consider that subjective symptoms and clinical findings are essential to early diagnosis of AS, but HLA-B27 examination and family history are supportive.

Adolescent↗