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151.
Staphylococcus aureus is the primary etiological agent of several human diseases. S. aureus has classically been considered an extracellular pathogen; however, recent evidence indicates that S. aureus invades and persists in non-professional phagocytes. Experiments demonstrate that actin microfilaments, microtubules, receptor-mediated endocytosis, and protein tyrosine kinases play important roles in the uptake of S. aureus. Fibronectin-binding proteins and beta-integrins are implicated as critical cell surface molecules associated with internalization of S. aureus by non-phagocytic cells. Following invasion of eukaryotic cells, S. aureus induces the release of cytokines that have the potential to exacerbate disease and induce apoptosis. Finally, S. aureus has the ability to persist inside host cells as small colony variants, a phenotype associated with persistent and recurrent infections. 相似文献
152.
Amano S Scott IC Takahara K Koch M Champliaud MF Gerecke DR Keene DR Hudson DL Nishiyama T Lee S Greenspan DS Burgeson RE 《The Journal of biological chemistry》2000,275(30):22728-22735
Epithelial cells maintained in culture medium containing low calcium proteolytically process laminin 5 (alpha3beta3gamma2) within the alpha3 and gamma2 chains (). Experiments were designed to identify the enzyme(s) responsible for the laminin 5 processing and the sites of proteolytic cleavage. To characterize the nature of laminin 5 processing, we determined the N-terminal amino acid sequences of the proteolytic fragments produced by the processing events. The results indicate that the first alpha3 chain cleavage (200-l65 kDa alpha3) occurs within subdomain G4 of the G domain. The second cleavage (l65-l45 kDa alpha3) occurs within the lIla domain, 11 residues N-terminal to the start of domain II. The gamma chain is cleaved within the second epidermal growth factor-like repeat of domain Ill. The sequence cleaved within the gamma2 chain matches the consensus sequence for the cleavage of type I, II, and III procollagens by bone morphogenetic protein-1 (BMP-1), also known as type I procollagen C-proteinase (). Recombinant BMP-1 cleaves gamma2 in vitro, both within intact laminin 5 and at the predicted site of a recombinant gamma2 short arm. alpha3 is also cleaved by BMP-1 in vitro, but the cleavage site is yet to be determined. These results show the laminin alpha3 and gamma2 chains to be substrates for BMP-1 in vitro. We speculate that gamma2 cleavage is required for formation of the laminin 5-6 complex and that this complex is directly involved in assembly of the interhemidesmosomal basement membrane. This further suggests that BMP-1 activity facilitates basement membrane assembly, but not hemidesmosome assembly, in the laminin 5-rich dermal-epidermal junction basement membrane in vivo. 相似文献
153.
The diversity and population densities of facultative anaerobic bacteria with the capacity to hydrate oleic acid and linoleic acid in the rumen of sheep and dairy cows were determined. The screening of representative colonies, from rumen fluid plated aerobically on a range of agar media, revealed that sheep rumen fluid contained hydration-positive strains of Streptococcus, Staphylococcus, Enterococcus, Lactobacillus and Pediococcus, whereas cow rumen fluid contained hydration-positive strains of Streptococcus, Lactobacillus and Staphylococcus. Mean counts of facultative anaerobic bacteria in sheep and cattle rumen were log10 7.29 and log10 6.40, respectively, and were independent of diet. Approximately 56% of facultative anaerobic bacteria were able to hydrate oleic and/or linoleic acid in anaerobic broth culture. For both sheep and cows, the most numerous hydration-positive isolates were strains of Strep. bovis. The results, which are the first to show that pediococci have the capacity to hydrate unsaturated fatty acids, suggest that lactic acid bacteria are the major unsaturated fatty acid hydrating bacteria in the rumen. 相似文献
154.
Growth, adipose, brain, and skin alterations resulting from targeted disruption of the mouse peroxisome proliferator-activated receptor beta(delta) 总被引:4,自引:0,他引:4 下载免费PDF全文
Peters JM Lee SS Li W Ward JM Gavrilova O Everett C Reitman ML Hudson LD Gonzalez FJ 《Molecular and cellular biology》2000,20(14):5119-5128
To determine the physiological roles of peroxisome proliferator-activated receptor beta (PPARbeta), null mice were constructed by targeted disruption of the ligand binding domain of the murine PPARbeta gene. Homozygous PPARbeta-null term fetuses were smaller than controls, and this phenotype persisted postnatally. Gonadal adipose stores were smaller, and constitutive mRNA levels of CD36 were higher, in PPARbeta-null mice than in controls. In the brain, myelination of the corpus callosum was altered in PPARbeta-null mice. PPARbeta was not required for induction of mRNAs involved in epidermal differentiation induced by O-tetradecanoylphorbol-13-acetate (TPA). The hyperplastic response observed in the epidermis after TPA application was significantly greater in the PPARbeta-null mice than in controls. Inflammation induced by TPA in the skin was lower in wild-type mice fed sulindac than in similarly treated PPARbeta-null mice. These results are the first to provide in vivo evidence of significant roles for PPARbeta in development, myelination of the corpus callosum, lipid metabolism, and epidermal cell proliferation. 相似文献
155.
Previously we reported that ultralow concentrations of dynorphins (10(-16) to 10(-12) M) inhibited lipopolysaccharide (LPS)-induced production of nitric oxide (NO) and proinflammatory cytokines in mouse glia without the participation of kappa-opioid receptors. In the current study using mouse cortical neuron-glia cocultures, we examined the possibility that inhibition of glia inflammatory response by dynorphins might be neuroprotective for neurons. LPS, in a concentration-dependent manner, markedly increased the release of lactate dehydrogenase (LDH), an indicator of cellular injury. Ultralow concentrations (10(-14) to 10(-12) M) of dynorphin (dyn) A-(1-8) significantly prevented the LPS-induced release of LDH, loss of neurons, and changes in cell morphology, in addition to inhibition of LPS-induced nitrite production. Meanwhile, ultralow concentrations (10(-15) to 10(-13) M) of des-[Tyr(1)]-dyn A-(2-17), a nonopioid peptide which does not bind to kappa-opioid receptors, exhibited the same inhibitory effect as dyn A-(1-17). These results suggest that dynorphins at ultralow concentrations are capable of reducing LPS-induced neuronal injury and these neuroprotective effects of dynorphins are not mediated by classical opioid receptors. 相似文献
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159.
This study quantified the relationship between calibrated caliper and ultrasonographic derived measurements of bovine testicles in vivo with actual testicular length, width, volume and weight. The prolate spheroid formula was tested to accurately predict testicular volume and a modification to predict weight. Ten bulls were employed to derive caliper and ultrasound testicle (n = 20) length and width measurements in vivo. Caliper length measurements were more reliable than ultrasound derived lengths, with correlations of r2 = 0.8023; P < 0.05 and r2 = 0.5111; P < 0.05, respectively. Width for both the calipers and ultrasound measurements when compared to actual width measurements were r2 = 0.7313; P < 0.05 and r2 = 0.8310; P < 0.05, respectively. The prolate spheroid formula is reliable in determining testicle (n = 116) volume (r2 = 0.8928; P < 0.05). Testicular volume and weight are highly correlated (r2 = 0.9776; P < 0.05); therefore, a modification of the prolate spheroid formula was used to predict weight (r2 = 0.9084; P < 0.05) against the actual weight. Caliper-derived length and width measurements used in the prediction of volume and weight had correlation coefficients against actual volume and weight of r2 = 0.5497; P < 0.05 and r2 = 0.6340; P < 0.05, respectively. Ultrasound in vivo measurements for prediction of testicular volume and testicular weight had a correlation of r2 = 0.3276; P < 0.05 and r2 = 0.6249; P < 0.05, respectively. A testicular (n = 116) length to width ratio of 1.8:1 (SEM = 0.01) was determined for both slaughterhouse and castrated animals. Caliper measurements are reliable, inexpensive and much simpler to obtain than ultrasound determinations for in vivo testicle length, width, volume and weight. The two-dimensional measurement of length and width would be a more accurate predictor of testicle volume and weight than the one-dimensional measurement of scrotal circumference (SC), especially in bulls with variation in testicular shape. 相似文献
160.
Robyn Hudson Marylin Rangassamy Amor Saldaña Oxána Bánszegi Heiko G Rödel 《Frontiers in zoology》2015,12(Z1):S12