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Background
There has been no comprehensive study on biochemical characterization of insecticide resistance mechanisms in field populations of Malaysian Culex quinquefasciatus. To fill this void in the literature, a nationwide investigation was performed to quantify the enzyme activities, thereby attempting to characterize the potential resistance mechanisms in Cx. quinquefasciatus in residential areas in Malaysia.Methodology/Principal Findings
Culex quinquefasciatus from 14 residential areas across 13 states and one federal territory were subjected to esterases, mixed function oxidases, glutathione-S-transferase and insensitive acetylcholinesterase assays. Enzyme assays revealed that α-esterases and β-esterases were elevated in 13 populations and 12 populations, respectively. Nine populations demonstrated elevated levels of mixed function oxidases and glutathione-S-transferase. Acetylcholinesterase was insensitive to propoxur in all 14 populations. Activity of α-esterases associated with malathion resistance was found in the present study. In addition, an association between the activity of α-esterases and β-esterases was also demonstrated.Conclusions/Significance
The present study has characterized the potential biochemical mechanisms in contributing towards insecticide resistance in Cx. quinquefasciatus field populations in Malaysia. Identification of mechanisms underlying the insecticide resistance will be beneficial in developing effective mosquito control programs in Malaysia. 相似文献Background
Interaction of transmembrane mucins with the multivalent carbohydrate-binding protein galectin-3 is critical to maintaining the integrity of the ocular surface epithelial glycocalyx. This study aimed to determine whether disruption of galectin-3 multimerization and insertion of synthetic glycopolymers in the plasma membrane could be used to modulate glycocalyx barrier function in corneal epithelial cells.Methodology/Principal Findings
Abrogation of galectin-3 biosynthesis in multilayered cultures of human corneal epithelial cells using siRNA, and in galectin-3 null mice, resulted in significant loss of corneal barrier function, as indicated by increased permeability to the rose bengal diagnostic dye. Addition of β-lactose, a competitive carbohydrate inhibitor of galectin-3 binding activity, to the cell culture system, transiently disrupted barrier function. In these experiments, treatment with a dominant negative inhibitor of galectin-3 polymerization lacking the N-terminal domain, but not full-length galectin-3, prevented the recovery of barrier function to basal levels. As determined by fluorescence microscopy, both cellobiose- and lactose-containing glycopolymers incorporated into apical membranes of corneal epithelial cells, independently of the chain length distribution of the densely glycosylated, polymeric backbones. Membrane incorporation of cellobiose glycopolymers impaired barrier function in corneal epithelial cells, contrary to their lactose-containing counterparts, which bound to galectin-3 in pull-down assays.Conclusions/Significance
These results indicate that galectin-3 multimerization and surface recognition of lactosyl residues is required to maintain glycocalyx barrier function at the ocular surface. Transient modification of galectin-3 binding could be therapeutically used to enhance the efficiency of topical drug delivery. 相似文献Matrix metallopeptidase 2 (MMP-2) and matrix metallopeptidase 9 (MMP-9) are involved in the breakdown of extracellular matrix in normal physiological processes as well as in disease processes, such as cancer metastasis. We conducted this work to study the role of MMP-2 and MMP-9 in breast cancer by measuring their plasma concentrations before and after surgery. Also, to examine if their levels can reflect the stage of disease and prognosis. Forty-eight breast cancer patients and 13 patients with benign breast diseases were included in the study. MMP-2 and MMP-9 levels were measured by ELISA and semi-quantitative real-time PCR. MMP-2 and MMP-9 levels in plasma were determined by ELISA immediately before surgery and during 6 to 12 months after curative surgery. We observed a significant increase in the level of MMP-9 mRNA expression in breast cancer patients in comparison to their normal breast tissues and to tissues of benign breast disease. In all TNM tumor stages, the plasma levels of MMP-2 and MMP-9 were increased significantly before curative surgery in the studied patients with breast carcinoma and decreased significantly after surgery. Both MMP-2 and MMP-9 may be used as a possible marker for follow-up or as a marker that reflects the response of the disease to treatment.
相似文献Noise has always been an important environmental factor that induces health problems in the general population. Due to ever increasing noise pollution, humans are facing multiple auditory and non-auditory problems including neuropsychiatric disorders. In modern day life it is impossible to avoid noise due to the rapid industrialization of society. Continuous exposure to noise stress creates a disturbance in brain function which may lead to memory disorder. Therefore, it is necessary to find preventive measures to reduce the deleterious effects of noise exposure. Supplementation of taurine, a semi essential amino acid, is reported to alleviate psychiatric disorders. In this study noise-exposed (100 db; 3 h daily for 15 days) rats were supplemented with taurine at a dose of 100 mg/kg for 15 days. Spatial and recognition memory was assessed using the Morris water maze and novel object recognition task, respectively. Results of this study showed a reversal of noise-induced memory impairment in rats. The derangements of catecholaminergic and serotonergic levels in the hippocampus and altered brain antioxidant enzyme activity due to noise exposure were also restored by taurine administration. This study highlights the importance of taurine supplementation to mitigate noise-induced impaired memory via normalizing the neurochemical functions and reducing oxidative stress in rat brain.
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