Biomedical subjects

Ming Ding

Publications and source records attributed to Ming Ding.

24 records · Page 2Linked to original sources

PubMed2003

Compacted cancellous bone has a spring-back effect.

A new surgical technique, compaction, has been shown to improve implant fixation. It has been speculated that the enhanced implant fixation with compaction could be due to a spring-back effect of compacted bone. However, such an effect has yet to be shown. Therefore we investigated in a canine model whether implant cavities prepared with compaction had spring back. Before killing the animals, we used one of two surgical techniques to make implant cavities of identical dimensions in both lateral femoral condyles of 7 dogs. One side had the implant cavity prepared with compaction, the other side with drilling. The cavities were left empty in vivo for 10 minutes before the dogs were killed. Postoperative micro-CT scanning showed that the diameters of the compacted cavities were significantly smaller than those of the drilled cavities, although they had had identical dimensions initially. Thus we found a spring-back effect of compacted bone, which may be important for increasing implant fixation by reducing initial gaps between the implant and bone.

Animals↗

PubMed2003

Isolation of a multi-functional endogenous cellulase gene from mollusc, Ampullaria crossean.

The cellulase genes of some animals, most coding for endo-beta-1,4-glucanases, were found and cloned. There has been no reports about genes encoding exo-beta-1,4-glucanase or endo- -1,4-xylanase from animal. Here we cloned the cDNA of a cellulase designated as EGX from mollusc, Ampullaria crossean, and expressed it in Pichia pastoris for the first time. The cellulase EGX is a multi-functional beta cellulase with the activities of exo-beta-1,4-glucanase, endo-beta-1,4-glucanase and endo-beta-1,4-xylanase. The opening reading frame of EGX cDNA is 1185 bp and encodes 395 amino acids. The EGX gene can also be amplificated from the genomic DNA by PCR, which verified the endogenous origin of this gene. This EGX gene was the first multi-functional cellulase gene that was directly isolated from animals.

Amino Acid Sequence↗

PubMed2003

[Distribution of the HIV/AIDS associated CCR5Delta32,CCR2b-64I,SDF1-3'A allelesin Chinese Dai and Chingpaw populations from Dehong autonomous prefecture of Yunnan Province].

The purpose of the work is to investigate the frequencies and polymorphisms of HIV-1 resistant CCR5delta32,CCR2b-64I,SDF1-3'A alleles in Chinese Dai and Chingpaw populations. Whole blood samples from 101 Dai subjects and 113 Chingpaw were collected randomly and their genomic DNA were extracted with QIAgen Blood Kits. Allelic frequencies were identified by PCR-RFLP analysis. Allelic polymorphisms in Dai population or Chingpaw population and both sexes in the samples were analyzed by chi(2) test. The frequencies of CCR5delta32,CCR2b-64I,SDF1-3'A alleles in Dai population were 0.0000,0.2130,0.2030, respectively. The frequencies of CCR5delta32,CCR2b-64I,SDF1-3'A alleles in Chingpaw population were 0.000, 0.1637, 0.1770, respectively. Distributions of the CCR2b-64I,SDF1-3'A alleles among the both populations were in accordance with Hardy-Weinberg equilibrium. No statistical difference was found in the allelic frequencies of both CCR2b-64I and SDF1-3'A between male and female individuals. The frequencies of CCR5delta32,CCR2b-64I alleles in Chinese Dai and Chingpaw populations are similar to that in Chinese Han population, while the frequency of SDF1-3'A allele in Chinese Dai and Chingpaw populations are lower in contrast to that in Chinese Han population. The genotyping and polymorphism of CCR5delta32,CCR2b-64I,SDF1-3'A alleles in Chinese Dai and Chingpaw populations of Yunnan Province are the first time studied in China. The significance of the three mutant alleles conferring genetic resistance to HIV-1 and AIDS progression remains to be clarified.

English Abstract↗

PubMed2002

Subcompartmentalization of HIV-1 quasispecies between seminal cells and seminal plasma indicates their origin in distinct genital tissues.

The mononuclear cells and plasma components of semen from HIV-infected subjects have been shown to contain HIV-1. However, there is very little information as to whether distinct HIV-1 population are present in these two seminal compartments or as to their tissue of origin. Phylogenetic analysis of nucleotide sequences of the C2-V5 region of the HIV-1 gp120 from HIV-1 RNA isolated from seminal cells and seminal plasma of five subjects indicates that the HIV-1 population derived from seminal plasma was distinct from that present in seminal cells. Such subcompartmentalization of HIV-1 between seminal cells and seminal plasma was detected as early as 3 months after seroconversion and persisted up to 38 months following seroconversion. Furthermore, comparison of HIV-1 sequences between testis and prostate tissues showed distinct HIV-1 populations in these tissue compartments. In situ real-time (Taqman) PCR analysis of prostate and testis tissues indicated that T lymphocytes were the predominant cells infected with HIV-1 in both of these tissues. Since seminal plasma is derived from prostate and most of the seminal cells originate from the rete testis and epididymis, these results are consistent with the idea that HIV-1 in seminal plasma is derived from the prostate, while HIV-1-infected cells in semen originate mostly from the rete testis and epididymis. These findings provide for the first time evidence of subcompartmentalization of HIV-1 in male genital organs and suggest that intervention strategies such as vasectomy may not prevent sexual transmission.

Acquired Immunodeficiency Syndrome↗

PubMed2002

Age-related variations in the microstructure of human tibial cancellous bone.

A thorough understanding of the microstructure of cancellous bone is crucial for diagnosis, prophylaxis, and treatment of age-related skeletal diseases. Until now, little has been known about age-related variations in the microstructure of peripheral cancellous bone. This study quantified age-related changes in the three-dimensional (3D) microstructure of human tibial cancellous bone. One hundred and sixty cylindrical cancellous bone specimens were produced from 40 normal proximal tibiae from 40 donors, aged 16-85 years. These specimens were micro-computed tomography (micro-CT) scanned, and microstructural properties were determined. The specimens were then tested in compression to obtain Young's modulus. The degree of anisotropy, mean marrow space volume, and bone surface-to-volume ratio increased significantly with age. Bone volume fraction, mean trabecular volume, and bone surface density decreased significantly with age. Connectivity did not have a general relationship with age. Bone volume fraction together with anisotropy best predicted Young's modulus. Age-related changes in the microstructural properties had the same trends for both medial and lateral condyles of the tibia. The observed increase of anisotropy and constant connectivity suggest a bone remodeling mechanism that may reorient trabecular volume orientation in aging tibial cancellous bone. The aging trabeculae align more strongly to the primary direction--parallel to the tibial longitudinal loading axis.

Adolescent↗

PubMed2002

Mutual associations among microstructural, physical and mechanical properties of human cancellous bone.

Previous studies have shown that low-density, rod-like trabecular structures develop in regions of low stress, whereas high-density, plate-like trabecular structures are found in regions of high stress. This phenomenon suggests that there may be a close relationship between the type of trabecular structure and mechanical properties. In this study, 160 cancellous bone specimens were produced from 40 normal human tibiae aged from 16 to 85 years at post-mortem. The specimens underwent micro-CT and the microstructural properties were calculated using unbiased three-dimensional methods. The specimens were tested to determine the mechanical properties and the physical/compositional properties were evaluated. The type of structure together with anisotropy correlated well with Young's modulus of human tibial cancellous bone. The plate-like structure reflected high mechanical stress and the rod-like structure low mechanical stress. There was a strong correlation between the type of trabecular structure and the bone-volume fraction. The most effective microstructural properties for predicting the mechanical properties of cancellous bone seem to differ with age.

Adolescent↗