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51.
软骨组织工程中力学因素的影响及应用 总被引:1,自引:0,他引:1
力学因素是软骨组织工程中的重要影响因素之一。近年来的研究表明,力学作用可以刺激细胞因子及激素的分泌,改变三维支架上培养的软骨细胞的新陈代谢,从而促进软骨组织的生长与重建。目前已经有诸多关于体外构建软骨组织的报道,但对于其中的力学因素的影响(包括力学因素对软骨细胞增殖的促进及力学刺激的传导机制等)还没有完全认识。就以上几方面做一综述,并简单介绍生物反应器在软骨组织工程中的应用。 相似文献
52.
Straube E Knöfel B Schneider T Schubert S Wetzker R 《International journal of medical microbiology : IJMM》2000,290(1):65-73
Adhesion to and internalization into host cells is an essential step in the pathogenesis of various bacterial infections. Here we investigated the effects of growth factors on the internalization of Escherichia coli O18 strains isolated from patients with urinary tract infection (UTI) by human epithelial cells. A dramatic increase in the uptake of Escherichia coli was observed after treatment of epithelial cells with epidermal growth factor (EGF) and to a lower extent with insulin. EGF-dependent internalization can be suppressed by tyrosine kinase inhibitors suggesting an involvement of the receptor tyrosine kinases in the regulation of the endocytotic process. Inhibitors of phospholipase A2, lipoxygenase, and cyclooxygenase significantly decreased internalization of bacteria induced by EGF. Finally, the specific inhibitor of PI 3-kinases Wortmannin was shown to suppress completely the EGF-independent internalization. The data of this analysis indicate the involvement of several signaling paths in bacterial internalization of uropathogenic Escherichia coli O18 strains and contribute to the comprehension of the pathogenesis of recurrent UTI. 相似文献
53.
Gaëlle Dzangué-Tchoupou Kuberaka Mariampillai Loïs Bolko Damien Amelin Wladimir Mauhin Aurélien Corneau Catherine Blanc Yves Allenbach Olivier Benveniste 《Autoimmunity reviews》2019,18(4):325-333
Background
Myositis is a heterogeneous group of muscular auto-immune diseases with clinical and pathological criteria that allow the classification of patients into different sub-groups. Inclusion body myositis is the most frequent myositis above fifty years of age. Diagnosing inclusion body myositis requires expertise and is challenging. Little is known concerning the pathogenic mechanisms of this disease in which conventional suppressive-immune therapies are inefficacious.Objectives
Our aim was to deepen our understanding of the immune mechanisms involved in inclusion body myositis and identify specific biomarkers.Methods
Using a panel of thirty-six markers and mass cytometry, we performed deep immune profiling of peripheral blood cells from inclusion body myositis patients and healthy donors, divided into two cohorts: test and validation cohorts. Potential biomarkers were compared to myositis controls (anti-Jo1-, anti-3-hydroxyl-3-methylglutaryl CoA reductase-, and anti-signal recognition particle-positive patients).Results
Unsupervised analyses revealed substantial changes only within CD8+ cells. We observed an increase in the frequency of CD8+ cells that expressed high levels of T-bet, and containing mainly both effector and terminally differentiated memory cells. The senescent marker CD57 was overexpressed in CD8+T-bet+ cells of inclusion body myositis patients. As expected, senescent CD8+T-bet+ CD57+ cells of both patients and healthy donors were CD28nullCD27nullCD127null. Surprisingly, non-senescent CD8+T-bet+ CD57- cells in inclusion body myositis patients expressed lower levels of CD28, CD27, and CD127, and expressed higher levels of CD38 and HLA-DR compared to healthy donors. Using classification and regression trees alongside receiver operating characteristics curves, we identified and validated a frequency of CD8+T-bet+ cells >51.5% as a diagnostic biomarker specific to inclusion body myositis, compared to myositis control patients, with a sensitivity of 94.4%, a specificity of 88.5%, and an area under the curve of 0.97.Conclusion
Using a panel of thirty-six markers by mass cytometry, we identify an activated cell population (CD8+T-bet+ CD57- CD28lowCD27lowCD127low CD38+ HLA-DR+) which could play a role in the physiopathology of inclusion body myositis, and identify CD8+T-bet+ cells as a predominant biomarker of this disease. 相似文献54.
Reduced protein tyrosine phosphatase (PTPase) activity of CD45 on peripheral blood lymphocytes in patients with systemic lupus erythematosus (SLE) 总被引:3,自引:0,他引:3
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To disclose the mechanism of aberrant function of peripheral blood lymphocytes (PBL) in SLE, we focused on the catalytic function of CD45, and determined the CD45 PTPase activity in SLE patients. The sample population consisted of 32 SLE patients with different disease activity. PTPase activity of cell lysates immunoprecipitated by anti-CD45 MoAb was assayed against phosphotyrosine analogue PNPP, followed by measuring the release of para-nitro phenol at 410 nm. CD45 PTPase activity of PBL was significantly decreased in SLE patients, compared with that of normal controls and patients with systemic sclerosis (964 ± 265, 1202 ± 172, 1210 ± 125, respectively; SLE versus normal, P < 0.05). It was correlated with SLE Disease Activity Index (SLEDAI) score (r = 0.597, P = 0.0006), but not with the dose of prednisolone (r = 0.214, P = 0.2657), indicating that CD45 PTPase activity became reduced when the disease was active, but it was not affected by prednisolone. Moreover, it was not corrected by in vitro culture with or without stimulation. The expression of CD45 on PBL was comparable between normal and SLE, raising a possibility that it may be due to aberrant regulation of catalytic function of CD45 in SLE. Given the evidence that tyrosine phosphorylation of cellular proteins by tyrosine kinases and phosphatases is one of the key biochemical events in the signal transduction pathway, the decreased CD45 PTPase activity in SLE may account for the defective signal transduction via TCR/CD3, leading to dysregulated effector function of the lymphocytes. 相似文献
55.
Mansy HA Hoxie SJ Patel NH Sandler RH 《Medical & biological engineering & computing》2005,43(1):56-62
Vascular access for renal dialysis is a lifeline for about 120 000 individuals in the United States. Stethoscope auscultation
of vascular sounds has some utility in the assessment of access patency, yet can be highly skill-dependent. The objective
of the study was to identify acoustic parameters that are related to changes in vascular access patency. The underlying hypothesis
is that stenoses of haemodialysis access vessels or grafts cause vascular sound changes that are detectable using computerised
data acquisition and analysis. Eleven patients participated in the study. Their vascular sounds were recorded before and after
angiography, which was accompanied by angioplasty in most patients. The sounds were acquired using two electronic stethoscopes
and then digitised and analysed on a personal computer. Vessel stenosis changes were found to be associated with changes in
acoustic amplitude and/or spectral energy distribution. Certain acoustic parameters correlated well (correlation coefficient=0.98,
p<0.0001) with the change in the degree of stenosis, suggesting that stenosis severity may be predictable from these parameters.
Parameters also appeared to be sensitive to modest diameter changes (>20%), (p<0.005, Wilcoxon rank sum test). These results
suggest that computerised analysis of vascular sounds may be useful in vessel patency surveillance. Further testing using
longitudinal studies may be warranted. 相似文献
56.
Roberto Merletti Mohamed A. Sabbahi Carlo J. De Luca 《European journal of applied physiology》1984,52(3):258-265
Summary A study was performed to investigate the changes that occur in the median frequency of the myoelectric signal during local ischemia or reduction of intramuscular temperature produced by surface cooling. Data was obtained from experiments which involved the first dorsal interosseous muscle of 10 female and 16 male subjects. These subjects were asked to perform isometric constant-force abduction contractions of the index finger at 20% and 80% of maximal voluntary contraction level. The initial median frequency (IMF) of the myoelectric signal during the first 0.5 s of contraction was calculated. Results showed a significant reduction of the IMF in contractions performed under ischemic conditions; upon release, the IMF recovered quickly. At 80% maximal voluntary level of contraction, a greater decrease of the IMF was recorded. Similar results were demonstrated during reduction of intramuscular temperature with gradual recovery of the IMF after cooling. These results demonstrate that the median frequency of the myoelectric signal displays behavior similar to that reported for conduction velocity and this is consistent with the notion that accumulation of metabolic byproducts in muscle tissue causes a decrease in the conduction velocity of the muscle fibers.Dr. R. Merletti was on a leave of absence from the Institute of Electrical Engineering, Politecnico di Torino, Italy 相似文献
57.
It is well established that the activation of T lymphocytes by mitogen/antigen is accompanied by a rise in intracellular free calcium ([Ca2+]i), changes in membrane potential, metabolism of inositol phospholipid, and activation of protein kinase C. Theseearly events of signal transduction culminate inlate events of lymphocyte activation, namely, DNA synthesis, lymphokine production, and cellular proliferation. In this study we examined the effect of human immunodeficiency virus (HIV) on changes in membrane potential and [Ca2+]i levels. The membrane potentials were markedly decreased (depolarized) in T cell lines infected with HIV (H9/HTLV IIIb) and did not respond normally to phytohemagglutinin (PHA) or anti-T3 (anti-CD3) monoclonal antibody compared to uninfected H9 cell line. The basal [Ca2+]i levels in H9/HTLV IIIb cells were increased in comparison to those in H9 cells; however, there was very little further increase in [Ca2+]i in H9/HTLV IIIb cells following activation with PHA or anti-T3 monoclonal antibody. This is in contrast to a significant rise in [Ca2+]i in H9 cells following similar stimulation. These data demonstrate abnormalities in the plasma membrane potential and [Ca2+]i levels in chronically infected T cells with HIV. These abnormalities in signal transduction of the T-cell activation pathway could be responsible for T-cell dysfunction in patients with HIV infection. 相似文献
58.
Improvement in Doppler ultrasound human foetal heart rate records by signal correlation 总被引:1,自引:0,他引:1
D. L. Tuck 《Medical & biological engineering & computing》1982,20(3):357-360
An improved method for the determination of foetal heart rate from Doppler ultrasound signals is described and evaluated.
It determines the most probable pulse interval from the recurrence times of multiple echoes generated by each cardiac pulse.
The method, when optimised, is shown to offer an improvement over current systems, especially in reduced signal loss. 相似文献
59.
60.