An approach for 3D bone tissue generation fromembryonic stem (ES) cells was investigated. The ES cells wereinduced to differentiate into osteogenic precursors, capable ofproliferating and subsequently differentiating into bone-formingcells. The differentiated cells and the seeded scaffolds werecharacterized using von Kossa and Alizarin Red staining, electronmicroscopy, and RT-PCR analysis. The results demonstrated thatES-derived bone-forming cells attached to and colonized thebiocompatible and biodegradable scaffolds. Furthermore, thesecells produced bone nodules when grown for 3–4 weeks inmineralization medium containing ascorbic acid andbeta-glycerophosphate both in tissue culture plates and inscaffolds. The differentiated cells also expressed osteospecificmarkers when grown both in the culture plates and in 3Dscaffolds. Osteogenic cells expressed alkaline phosphatase,osteocalcin, and osteopontin, but not an ES cell-specific marker,oct-4. These findings suggest that ES cell can be usedfor in vitro tissue engineering and cultivation of graftable skeletal structures. 相似文献
The vascularization of engineered tissues in many cases does not keep up with the ingrowth of cells. Nutrient and oxygen supply are not sufficient, which ultimately leads to the death of the invading cells. The enhancement of the angiogenic capabilities of engineered tissues therefore represents a major challenge in the field of tissue engineering. The immobilization of angiogenic growth factors may be useful for enhancing angiogenesis. The most potent angiogenic growth factor specific to endothelial cells, vascular endothelial growth factor (VEGF), occurs in several splice variants. The variant with 165 amino acids both has a high angiogenic activity and a high affinity for heparin. We therefore incorporated heparin molecules into collagen matrices by covalently cross-linking them to amino functions on the collagen. Physical binding of VEGF to the heparin may then prevent a rapid clearance from the implant, while the release rate may become coupled to the degradation of the collagen matrix. The modified matrices were characterized by determination of the extent of the heparin immobilization, the in vitro degradation rate by collagenase. For testing the angiogenic properties, non-modified and heparinized collagen specimens were--either loaded with VEGF or non-loaded--subcutaneously implanted on the back of rats. Specimens were explanted after varying periods of implantation, the dry weights and the hemoglobin contents, as well as immunostained histological sections were evaluated: heparinized collagen matrices loaded with VEGF are vascularized to a substantially higher extent as compared to non-modified matrices. 相似文献
A case of a 20 year old Japanese woman who developed thyroid cancer exhibiting unusual cribriform structures while being followed up for familial adenomatous polyposis/Gardner's syndrome is reported. The patient presented with osteomas, pigmented retinal lesions, and adenomas of the duodenum and the papilla of Vater, in addition to numerous adenomatous polyps in the colorectum. On ultrasonography, the thyroid cancer was localised to the right lobe and was identified as an irregular, internal echo tumour with a peripheral hypoechoic zone, measuring 1.8 cm in diameter. Histological examination of the resected tumour showed a concomitance of papillary proliferation and cribriform structures with follicles of varying sizes. These features can be distinguished from sporadic thyroid cancer. 相似文献
A case of postoperative prosthetic hip joint infection due to Campylobacter fetus subsp. fetus is described. Difficulties in isolation and antimicrobial susceptibility testing of this organism are discussed. 相似文献
HLA-A2 subtypes (A*0201 - *0212) were determined by oligotyping in HLA-A2 positive samples from four populations (Han Chinese, Dai Chinese, Caucasoids from Germany and Turkish individuals from Kayseri)(see table).
Two different findings can be concluded from this study: 1) Significant HLA-A*02 allelic variations found in four populations. A*0207 is the predominant A*02 allele in the Dai population and absent in the German Caucasian and the Turkish population. In contrast, A*0201 is the most prevalent allele in the Caucasian, Turkish and Han Chinese group. We also found a high proportion of A*0206 and A*0207 in Han Chinese. 2) A strong association has been found between A*0207 and HLA-B46 and DR9 in the Dai minority population. This haplotype is also found in Han Chinese. Three DNA samples from Turkish and one from the Dai population are presently being sequenced because the reaction pattern was out of the expected (Supported by SFB 217) 相似文献
Linkage studies in multiple sclerosis (MS) identified several susceptibility loci. One of these regions includes chromosome 17q11 where a meta-analysis of data from three genome scans suggested linkage. This region encodes a cluster of genes for beta-chemokines or CC chemokine ligands (CCLs), which may be involved in the development of MS lesions. Here we aimed to test if CCL alleles and haplotypes are associated with MS. Using methods of linkage and association, we observed deviations from the expected 50% transmission of haplotypes from unaffected parents to their affected children at CCL2, CCL11-CCL8-CCL13 and CCL3 within the investigated 1.85 MB chromosomal segment. Analyses of the linkage disequilibrium map support that variants with possible relevance to MS can be located within these subregions. Identification of MS associated CCL variants may have direct clinical significance, as it can lead to the design of small competitive antagonists of these molecules with beneficial effects in the treatment of patients with early and active disease. 相似文献