Biomedical subjects

Xiao Lu

Publications and source records attributed to Xiao Lu.

26 records · Page 2Linked to original sources

PubMed2004

Imaging coronary artery microstructure using second-harmonic and two-photon fluorescence microscopy.

The microstructural basis for the mechanical properties of blood vessels has not been directly determined because of the lack of a nondestructive method that yields a three-dimensional view of these vascular wall constituents. Here, we demonstrate that multiphoton microscopy can be used to visualize the microstructural basis of blood vessel mechanical properties, by combining mechanical testing (distension) of excised porcine coronary arteries with simultaneous two-photon excited fluorescence and second-harmonic generation microscopy. Our results show that second-harmonic generation signals derived from collagen can be spectrally isolated from elastin and smooth muscle cell two-photon fluorescence. Two-photon fluorescence signals can be further characterized by emission maxima at 495 nm and 520 nm, corresponding to elastin and cellular contributions, respectively. Two-dimensional reconstructions of spectrally fused images permit high-resolution visualization of collagen and elastin fibrils and smooth muscle cells from intima to adventitia. These structural features are confirmed by coregistration of multiphoton microscopy images with conventional histology. Significant changes in mean fibril thickness and overall wall dimension were observed when comparing no load (zero transmural pressure) and zero-stress conditions to 30 and 180 mmHg distension pressures. Overall, these data suggest that multiphoton microscopy is a highly sensitive and promising technique for studying the morphometric properties of the microstructure of the blood vessel wall.

Animals↗

PubMed2004

Preparation of monoclonal antibodies against different epitopes on extracellular domain of human receptor for advanced glycation end product.

OBJECTIVE: To prepare and characterize monoclonal antibodies (mAb) against recombinant human receptor for advanced glycation end product (rhRAGE). METHODS: BALB/c mice were immunized with recombinant extracellular domain amino acid 23-342 of human advanced glycation end product (RAGE), and hybridoma was generated with mouse spleen cells and myeloma NS-1 cells. After three fusions and cloning, two hybridoma cell lines secreting monoclonal antibodies to RAGE were obtained and monoclonal antibodies were purified from the ascites followed by characterization with indirect enzyme-linked immunosorbent assay (ELISA), flow cytometry and Western blotting. RESULTS AND CONCLUSION: Two hybridoma cell lines secreting anti-RAGE mAb were established and designated as B2.2 and E10, respectively. Both of mAb B2.2 and E10 belonged to IgG2b isotype and could bind to recombinant RAGE and natural RAGE expressed on THP-1 cells. In addition, B2.2 and E10 could recognize different epitopes of RAGE, which were conformed to be capable of detecting soluble recombinant RAGE in sandwich ELISA. These two mAbs against different epitopes of rhRAGE would be useful for study of glycation end product and RAGE-related diseases.

Animals↗

PubMed2004

[Construction of the expression vector PcDNA4/His C-MBL and its expression in Chinese-hamster ovary cells].

OBJECTIVE: To construct pcDNA4/His C-MBL recombinant eukaryotic expression plasmid and examine its expression of mannan-binding lectin (MBL) in mammary cells. METHODS: The target sequence was amplified by PCR from pGEM-MBL plasmid that contains wild-type human MBL cDNA, and inserted into eukaryotic expression vector PcDNA4/His C followed by restriction mapping and sequencing. The recombinant plasmid PcDNA4/His C-MBL was transformed into Chinese-hamster ovary (CHO) cells by electroporation, and the Zeocin-resistant clones were selected for analysis of mRNA expression by reverse transcription (RT)-PCR. The expressed product was purified by immobilized metal affinity chromatography (IMAC) and identified by SDS-PAGE and Western-blot analysis, and its immunoreactivity was detected by an indirect enzyme-linked immunosorbent assay ELISA using the anti-serum from Balb/C mice immunized with the recombinant protein. RESULTS: The cDNA fragment of 750 bp was amplified from pGEM-MBL plasmid, which was shown by restriction enzyme digestion and DNA sequencing. The mRNA expression of Zeocin-resistant CHO cell clones was detected by RT-PCR. Three components of 29, 58 and 87 kD in the purified recombinant product were found by SDS-PAGE and the 29 kD component could be recognized by anti-6His antibody in Western blot analysis. The titers of the anti-serum from immunized mice were 1: 819 200 against the recombinant protein and 1:25 600 against both the natural human MBL and the recombinant trimeric carbohydrate-recognition domain (CRD) of human MBL, as determined by the indirect ELISA. CONCLUSION: The cell strains that express recombinant human MBL (rhMBL) and rhMBL protein have been obtained successfully, which provides the basis for further research of MBL molecule.

Animals↗

PubMed2003

Effect of passive myocardium on the compliance of porcine coronary arteries.

The objective of this study was to determine the effect of passive myocardium on the coronary arteries under distension and compression. To simulate distension and compression, we placed a diastolic-arrested heart in a Lucite box, where both the intravascular pressure and external (box) pressure were varied independently and expressed as a pressure difference (DeltaP = intravascular pressure - box pressure). The DeltaP-cross-sectional area relationship of the first several generations of porcine coronary arteries and the DeltaP-volume relationship of the coronary arterial tree (vessels >0.5 mm in diameter) were determined using a video densitometric technique in the range of +150 to -150 mmHg. The vasodilated left anterior descending (LAD) coronary artery of six KCl-arrested hearts were perfused with iodine and 3% Cab-O-Sil. The intravascular pressure was varied in a triangular pattern, whereas the absolute cross-sectional area of each vessel and the total arterial volume were calculated using video densitometry under different box pressures (0, 50, 100, and 150 mmHg). In the range of positive DeltaP, we found that the compliance of the proximal LAD artery in situ (4.85 +/- 3.8 x 10-3 mm2/mmHg) is smaller than that of the same artery in vitro (16.5 +/- 6 x 10-3 mm2/mmHg; P = 0.009). Hence, the myocardium restricts the compliance of the epicardial artery under distension. In the negative DeltaP range, the LAD artery does not collapse, whereas the same vessel readily collapses when tested in vitro. Hence, we conclude that myocardial tethering prevents collapse of large blood vessel under compression.

Angiography, Digital Subtraction↗

PubMed2003

Molecular cloning and characterization of mannan binding lectin C gene from Balb/c mice.

OBJECTIVE: To obtain full-length cDNA encoding mouse mannan-binding lectin C(MBL-C) polypeptide. METHODS: The cDNA encoding mouse MBL-C was isolated from Balb/c mouse liver cells by reverse transcriptase (RT)-PCR and inserted into pUC-T vector, and the encoding region structure of the DNA was analyzed to understand its evolutionary relationship with single human MBL homologues. RESULTS: The amplified mouse MBL-C cDNA, which was 735 bp in length, encoded 245 amino acid residues, and its structural analysis showed 100% homology with published mouse MBL-C gene sequence and 71.4% homology with MBL gene of Chinese human. CONCLUSION: The gene encoding Balb/c mouse MBL-C has been successfully isolated, which may facilitate further study of the innate immune functions of MBL molecule in vivo.

Animals↗

PubMed2002

Remodelling of the left anterior descending artery in a porcine model of supravalvular aortic stenosis.

BACKGROUND: Knowledge of the adaptive mechanisms of structure and function of coronary arteries in response to physical stress is important in human health and disease. OBJECTIVE: To gain a better understanding of the adaptive mechanisms of morphology in the zero-stress state of the coronary arteries in a porcine model of hypertension and flow overload. METHODS: The effects of simultaneous increases in pressure and flow were examined by studying the left anterior decending (LAD) artery in supravalvular aortic stenosis (SVAS). In this model, the pressure is uniformly increased along the length of the LAD artery trunk, whereas the increase in flow is significantly greater in the proximal than in the distal artery. The longitudinal variation of vessel dimension, medial and adventitial area, opening angle and residual strains were examined in the LAD arteries of aortic-banded (n = 5) and control (n = 5) pigs. RESULTS: Our results show that the wall shear stress was normalized, whereas the circumferential stress was increased, in the proximal portion of the LAD artery after 5 weeks of SVAS. In the distal artery, both shear and circumferential stresses were normalized. The vessel wall area was also increased in the remodelled vessels as the result of an increase in the medial and adventitial area. CONCLUSION: The major conclusion of this study is that, in the SVAS model, the remodelling process of the coronary artery is consistent with normalization of shear stress despite an increase in the circumferential stress. Furthermore, the remodelling of the zero-stress state is also dominated by flow overload.

Adaptation, Physiological↗

PubMed2002

[Effects of mechanical strain on the proliferation of pulmonary epithelial cells and reorganization of integrins].

Using a cyclic strain unit, the proliferation and reorganization of alpha(5), beta(1 ) integrins in human pulmonary epithelial A549 cells that underwent mechanical strain were studied. Flow cytometry revealed that cellular proliferative index reduced significantly after cells were subjected to 15% elongation at frequency 20 cycles/min or 40 cycles/min for 48 h. Confocal microscopy revealed that alpha(5), beta(1 ) integrins in human pulmonary epithelial A549 cells transferred from the apic al layer to the basal layer and created adhesion plaques after 24 h exposure to 15% elongation at frequency 40 cycles/min. It is concluded that alpha(5), beta(1 ) integrins in pulmonary epithelial cells play an important role in transducing mechanical stress into intracellular signals.

Cell Division↗

PubMed2002

[Oral microflora of 42 patients with oral squamous cell carcinoma].

OBJECTIVE: The purpose of this study was to evaluate the effects of squamous cell carcinoma on oral bacteria. METHODS: This study investigated the microbial contents of the plaque on the surfaces of oral squamous cell carcinomas. Samples were obtained from the central surface of lesions, contiguous healthy mucosa and saliva of 42 patients with oral squamous carcinoma before and after operation. RESULTS: The median of bacterial colony forming units per milliliter (CFUs/ml) of saliva before operation was 8.10 x 10(8) CFUs/ml. The median of CFUs per square centimeter of the tumor surface was 5.21 x 10(5) CFUs/cm2 which was significantly higher than that of the healthy (the control) mucosa (1.77 x 10(4) CFUs/cm2, P = 0.0001). The CFUs per square centimeter of mucosa surface at the operative zone was 4.34 x 10(5) CFUs/cm2 which was also significantly higher than that of the healthy (control) mucosa(7.24 x 10(4) CFUs/cm2, P = 0.0001). CONCLUSION: Oral carcinoma can break the balance of oral microflora, which may be one of the reasons leading to the high susceptivity of these compromised patients to systemic infection.

Adult↗