Search

In view ofsuch characteristicsas design standards and userequirements for the airport concrete pavement,analyses are made of the existing domestic frost resistanceevaluation indicesof concrete. The results suggest that the decline of relative dynamic elastic modulus to 60% and 5% of mass loss ratio in the test specimens, as stated in the current evaluation method of concrete freeze-thaw tests, are not rational evaluation indiceswith regard to the freeze-thaw damage to the airport concrete pavement.So it is considered more advisable to establishthe flexural strength loss ratioof test specimens and the extentto which their surface scalesoffas the frost resistance evaluation indices of airport concrete pavement.For which purpose, the fast-freeze method is adopted to conduct a freeze-thaw damage test on concrete specimens. And, according tothe correlation between the flexural strength loss and the decline of relative dynamic elastic modulus as well as that between the degree of surface scale-off and the mass loss ratio during the freeze-thaw process, the thresholds for specific evaluation indices of airport concrete pavement are supposed as follows. After 300 cycles of fast freezing and thawing, the relative dynamic elastic modulus of concrete specimens is noless than 75% (the correlative flexural strength loss ratio of the specimens is no greater than 46%), their scale-off area is somewhere between 1/3 and 2/3 of the whole surface, and their mass loss ratio no less than 1.0% (moderate scale-off). [ABSTRACT FROM AUTHOR]

The aim of the current research work was to study the chemical composition of the essential oil of Monarda punctata along with evaluating the essential oil and its major components for their antibacterial effects against some frequently encountered respiratory infection causing pathogens. Gas chromatographic mass spectrometric analysis revealed the presence of 13 chemical constituents with thymol (75.2%), p-cymene (6.7%), limonene (5.4), and carvacrol (3.5%) as the major constituents. The oil composition was dominated by the oxygenated monoterpenes. Antibacterial activity of the essential oil and its major constituents (thymol, p-cymene, limonene) was evaluated against Streptococcus pyogenes, methicillin-resistant Staphylococcus aureus (MRSA), Streptococcus pneumoniae, Haemophilus influenzae and Escherichia coli. The study revealed that the essential oil and its constituents exhibited a broad spectrum and variable degree of antibacterial activity against different strains. Among the tested strains, Streptococcus pyogenes, Escherichia coli and Streptococcus pneumoniae were the most susceptible bacterial strain showing lowest MIC and MBC values. Methicillin-resistant Staphylococcus aureus was the most resistant bacterial strain to the essential oil treatment showing relatively higher MIC and MBC values. Scanning electron microscopy revealed that the essential oil induced potent and dose-dependent membrane damage in S. pyogenes and MRSA bacterial strains. The reactive oxygen species generated by the Monarda punctata essential oil were identified using 2', 7'-dichlorofluorescein diacetate (DCFDA).This study indicated that the Monarda punctata essential oil to a great extent and thymol to a lower extent triggered a substantial increase in the ROS levels in S. pyogenes bacterial cultures which ultimately cause membrane damage as revealed by SEM results.

Objective: To investigate the effects of leukemia inhibitory factor (LIF) on renal interstitial fibroblast activation following induction by transforming growth factor beta 1 (TGF-beta1)., Methods: Normal rat interstitial fibroblast cells (NRK/49F) were treated with TGF-beta1 and TGF-beta1, combining with LIF respectively for different duration with different concentration. Changes in cell morphology and expression of alpha-SMA were evaluated with electronic microscope and Western blot respectively. The collagen I in the supernatant was detected with ABC-ELISA., Results: TGF-beta1 induced renal interstitial fibroblast activation, and this was accompanied by significant morphological transformations and secretion of collagen I. Co-culturing of cells with LIF blocked the morphological transformation. In addition, LIF inhibited TGF-beta1-induced expression of alpha-SMA mRNA and protein (P < 0.01), and decreased the levels of collagen I (P < 0.01) in a dose-dependent manner., Conclusion: LIF suppresses TGF-beta1-induced activation and collagen I secretion of cultured renal interstitial fibroblasts.

Objective: To investigate the effect and possible mechanism of salidroside on the transdifferentiation of normal rat kidney tubular epithelia cells (NRK52E) under cobaltous chloride (Co) induced hypoxic status., Methods: Cultured NRK52E cells were divided into control group, Co group and Co plus salidroside treatment groups at a dosage of 10 micromol/L, 50 micromol/L, and 100 micromol/L. Hypoxia-inducible factor-1alpha (HIF-1alpha), a master regulator of oxygen homeostasis was measured as a marker of hypoxic status. Morphologic alteration of cells was observed by inverted phase contrast microscope. The expression of alpha-SMA in NRK52E cells was detected by fluorescent immunocytochemistry (FICC) and immunohistochemistry (IHC). The alpha-SMA and TGF-beta1 mRNA were assessed using reverse transcription-polymerase chain reaction (RT-PCR). The expressions of HIF-1alpha and alpha-SMA protein were detected by Western blot analyses. The enzyme-linked immunosorbent assay was performed to detect collagen I (Col-I) and fibronectin (FN) in the supernatant., Results: The expression of HIF-1alpha in NRK52E cells was induced by 100 micromol/L of Co in vitro. Co induced transdifferentiation of NRK52E cells, showing fibroblast-like in morphology. Salidroside partly blocked morphologic transformation of tubular epithelial cells. Salidroside decreased the expressions of alpha-SMA protein and mRNA and TGF-beta1 mRNA significantly (P < 0.05), although they were still higher than the controls (P <0 .05). Salidroside, especially in high dosage, inhibited the increase in Col-I and FN induced by Co (P < 0.05)., Conclusion: Hypoxia can induce tubular epithelial-myofibroblast transdifferentiation (TEMT). Salidroside improves Co-induced hypoxic status and inhibits TEMT possibly through reducing Col I and FN in NRK52E cells.