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排序方式: 共有673条查询结果,搜索用时 15 毫秒
1.
T. M. Skerry M.D. M.R.C.V.S. R. Suswillo A. J. El Haj N. N. Ali R. A. Dodds L. E. Lanyon 《Calcified tissue international》1990,46(5):318-326
Summary Previous studies of Alcian blue-induced birefringence in adult avian cortical bone showed that a short period of intermittent
loading rapidly produces an increased level of orientation of proteoglycans within the bone tissue. In the absence of further
loading, this persists for over 24 hours. We have proposed that this phenomenon could provide a means for “capturing” the
effects of transient strains, and so provide a persistent, constantly updated strain-related influence on osteocyte populations
related to the bones' averaged recent strain history, in effect, a “strain memory” in bone tissue. In our present study, we
use the Alcian blue-induced birefringence technique to demonstrate that proteoglycan orientation also occurs after intermittent
loading of both cortical and cancellous mammalian bonein vivo andin vitro. We also show that the change in birefringence is proportional to the magnitude of the applied strain, and that the reorientation
occurs rapidly, reaching a maximal value after only 50 loading cycles. Examination of electron micrographs of bone tissue
after staining with cupromeronic blue allows direct visualization and quantification of the change in proteoglycan orientation
produced by loading. This shows that intermittent loading is associated with a realignment of the proteoglycan protein cores,
bringing them some 5 degrees closer to the direction of collagen fibrils in the bone matrix. 相似文献
2.
3.
Indole-3-carbinol and 3,3'-diindolylmethane induce apoptosis in human prostate cancer cells. 总被引:4,自引:0,他引:4
Cruciferous vegetables contain glucobrassicin which, during metabolism, yields indole-3-carbinol (I3C). In a low pH environment I3C is converted into polymeric products, among which 3,3'-diindolylmethane (DIM) is the main one. The apoptotic effects of I3C and DIM were exhibited in human breast cancer cells. The objectives of this study were: (a) examination of the potential effects of I3C and DIM on the proliferation and induction of apoptosis in human prostate cancer cell lines with different p53 status; (b) to try to characterise the mechanism(s) involved in these effects. Our results indicate that both indole derivatives suppress the growth of these cells in a dose- and time-dependent manner, by inducing apoptosis. It appears that these indolic compounds may offer effective means against prostate cancer. Induction of apoptosis was p53-independent. Moreover, the indole derivatives employed did not affect the levels of bcl-2, bax and fasL. 相似文献
4.
Mechanotransduction of bone cells<Emphasis Type="Italic">in vitro</Emphasis>: Mechanobiology of bone tissue 总被引:11,自引:0,他引:11
Mullender M El Haj AJ Yang Y van Duin MA Burger EH Klein-Nulend J 《Medical & biological engineering & computing》2004,42(1):14-21
Mechanical force plays an important role in the regulation of bone remodelling in intact bone and bone repair. In vitro, bone
cells demonstrate a high responsiveness to mechanical stimuli. Much debate exists regarding the critical components in the
load profile and whether different components, such as fluid shear, tension or compression, can influence cells in differing
ways. During dynamic loading of intact bone, fluid is pressed through the osteocyte canaliculi, and it has been demonstrated
that fluid shear stress stimulates osteocytes to produce signalling molecules. It is less clear how mechanical loads act on
mature osteoblasts present on the surface of cancellous or trabecular bone. Although tissue strain and fluid shear stress
both cause cell deformation, these stimuli could excite different signalling pathways. This is confirmed by our experimental
findings, in human bone cells, that strain applied through the substrate and fluid flow stimulate the release of signalling
molecules to varying extents. Nitric oxide and prostaglandin E2 values increased by between two- and nine-fold after treatment with pulsating fluid flow (0.6±0.3 Pa). Cyclic strain (1000
μstrain) stimulated the release of nitric oxide two-fold, but had no effect on prostaglandin E2. Furthermore, substrate strains enhanced the bone matrix protein collagen I two-fold, whereas fluid shear caused a 50% reduction
in collagen I. The relevance of these variations is discussed in relation to bone growth and remodelling. In applications
such as tissue engineering, both stimuli offer possibilities for enhancing bone cell growth in vitro. 相似文献
5.
Szalay F Zsarnovszky A Fekete S Hullár I Jancsik V Hajós F 《Anatomy and embryology》2001,203(1):53-59
Piglets born with spread-leg syndrome, a congenital weakness of the hindlimb adductors, were investigated to determine the site of lesion leading to limb impairment. Histological and immunohistochemical studies of the motor neuron unit showed no alterations but quantitative analysis revealed a reduction of axonal diameter and myelin sheath-thickness of the fibres innervating the adductors of the affected limbs. In the lumbar spinal cord a lack of myelination was observed in the tracts descending to the lower motor neurons. Recovery from the syndrome was accompanied by a catching-up of myelination with that of the controls. The spread-leg syndrome is due to a nutritional deficiency in the sow; thus it is assumed that the deficient maternal substances, mainly choline and methionine, are essential for the normal myelin production by spinal white matter oligodendrocytes of the fetus. 相似文献
6.
7.
Ben Jemaa Z Mahjoubi F Ben Haj H'mida Y Hammami N Ben Ayed M Hammami A 《Pathologie-biologie》2004,52(2):82-88
Antimicrobial susceptibility and frequency of occurrence of clinical blood isolates in Sfax-Tunisia (1993-1998). The choice of antimicrobial therapy for the treatment of bacteremia is often empirical and based on the knowledge of susceptibility profiles of the most common bacteria causing such infections. This study determines the bacterial etiology of bacteremic episodes and antimicrobial susceptibility patterns recorded at a teaching hospital, from January 1993 to December 1998. We collected 2979 strains responsible for bacteremia. Gram negative bacteria were predominant (60%). The organisms recovered most frequently were Staphylococcus aureus (18.9%), Escherichia coli (14.7%), Klebsiella pneumoniae (14%) and Pseudomonas aeruginosa (7.6%). The incidence of resistance to methicillin were 17.4% for Staphylococcus aureus and 26.8% for coagulase negative Staphylococcus. No resistance to glycopeptides was observed among the enterococci and staphylococci studied. 27.7% of enterobacteriaceae were resistant to third generation cephalosporins. Imipenem was the most active agent against gram negative bacteria. To carry out a surveillance of bacteremic episodes occurring at every hospital, it is necessary to provide valuable information which should be the basis for effective empiric therapy. 相似文献
8.
9.
The production of biochemical markers associated with the osteoblastic phenotype, and accompanying changes in the expression of voltage-operated Ca2+ channels, have been examined in rat bone marrow stromal cell cultures treated with dexamethasone (10-8 M). Whole cell clamp analysis of voltage-operated Ca2+ channels in control cultures (using Ba2+ as the charge carrier) revealed primarily a high voltage-activated (HVA), slowly inactivating current, which was enhanced two- to threefold by treatment of the cells with Bay K 8644 (300 nM) and inhibited by nifedipine (4 M). In dexamethasone-treated cultures, the I–V relationship for inward current was shifted to more positive potentials in comparison with control cells. Most cells in these cultures possessed both the HVA current and also a faster inactivating, low-voltage-activated (LVA), nifedepineresistant current. These two currents could be separated both by nifedipine and by the use of steady state inactivation of the LVA current. The two components of the Ba2+ current varied widely in their relative size. The combination of LVA and HVA currents seen in dex-induced stromal cells resembles records of voltage-operated Ca2+ channels from cultures of calvarial osteoblasts. 相似文献
10.
Ureaplasma urealyticum is a fastidious organism which is not recovered by conventional bacterial cultures techniques, but special cultures are required for its isolation and identification. As it is a urease-producing organism, it is considered a risk factor for the formation of struvite calculi in the urinary tract. A total of 30 patients with urinary infection stones (19 of them with the 1st formation and 11 with recurrent stone formation) were included in the study. Both bladder urine specimen (cystoscopically obtained) and stones removed were subjected to conventional cultures and also to Ureaplasma specific cultures (A7 agar and U9 broth). The results of culture techniques revealed that 86.7% of patients had aerobic organisms (E. coli in 46.7%, Klebsiella in 30%, Proteus in 6.7% and Pseudomonas in 3.3%) and 26.7% showed U. urealyticum in mid stream urine. As regards stone cultures, they revealed aerobic organisms in 76.7%, and U. urealyticum in 20%. Sensitivity tests for U. urealyticum showed that minocycline was the most effective antimicrobial followed by tetracycline and ciprofloxacin. From these data, we conclude that U. urealyticum may be the causative organism for infection stone and should be searched for via its specific cultures, especially in patients with recurrent stones and with the so-called sterile pyuria. 相似文献