Molecular dynamics study on the biophysical interactions of seven green tea catechins with lipid bilayers of cell membranes

Molecular dynamics simulations were performed to study the interactions of bioactive catechins (flavonoids) commonly found in green tea with lipid bilayers, as a model for cell membranes. Previously, multiple experimental studies rationalized catechin's anticarcinogenic, antibacterial, and other beneficial effects in terms of physicochemical molecular interactions with the cell membranes. To contribute toward understanding the molecular role of catechins on the structure of cell membranes, we present simulation results for seven green tea catechins in lipid bilayer systems representative of HepG2 cancer cells. Our simulations show that the seven tea catechins evaluated have a strong affinity for the lipid bilayer via hydrogen bonding to the bilayer surface, with some of the smaller catechins able to penetrate underneath the surface. Epigallocatechin-gallate (EGCG) showed the strongest interaction with the lipid bilayer based on the number of hydrogen bonds formed with lipid headgroups. The simulations also provide insight into the functional characteristics of the catechins that distinguish them as effective compounds to potentially alter the lipid bilayer properties. The results on the hydrogen-bonding effects, described here for the first time, may contribute to a better understanding of proposed multiple molecular mechanisms of the action of catechins in microorganisms, cancer cells, and tissues.     

山东省西瓜枯萎病病原菌的鉴定

 西瓜枯萎病是我省西瓜生产上重要病害,近年来危害严重,一般地块病株率20-30%,严重地块达80-100%,甚至绝产。     

Laser-excited fluorescence spectra of eastern SPF wood species. An optical technique for identification and separation of wood species?

Summary Use of UV-laser excitation to produce fluorescence spectra for heartwood and sapwood from jack pine (Pinus banksiana), white spruce (Picea glauca) and balsam fir (Abies balsamea) was examined. Spectra were fairly broad without sharp spectral features and overlap of spectra between species was common. Sample to sample and in-sample variation of the recorded fluorescence spectra was observed. The fluorescence spectra obtained from heartwood samples of jack pine showed evidence of photochemical bleaching as a result of the multiple laser pulses needed to produce a complete spectrum. Bleaching may have obscured differences between species. For the mix of species examined no sapwood nor heartwood samples were distinguishable by this technique with the detector used. Use of an optical multichannel analyzer (OMA) could reduce the number of laser pulses needed to obtain an entire spectrum. Under these conditions it would be possible to determine whether the minor differences in spectral features observed for the different species are more pronounced in the first few laser pulses and if they are characteristic of species. Certain aspects of the data suggest that with improved analytical equipment UV-fluorescence might prove to be a useful technique for the identification of certain species.     

THE ELECTRIC CONTROL TECHNIQUE OF THE HYDRAULIC LOGIC VALVE

This paper presen ts the electric con trol devive of the hydraulic logic valve.Itcontrains mainly two parts, a push button control and a microrocomputer wireless telecontrol.Thedesign and adjustment of the hardware and the software program are also presented.The results ofthe experments to the hydraulic system of the loader show that the device has the features of smallvolume,excellent performance,low cost and easy to develop software.     

Assessment of maxillary and infraorbital nerve blockade for rhinoscopy in sevoflurane anesthetized dogs

ObjectiveTo investigate the efficacy of maxillary and infraorbital nerve blocks for prevention of cardiovascular and qualitative responses to rhinoscopy, as well as response to skin clamping after assigned nerve block placement.Study designRandomized, blinded, placebo‐controlled cross‐over experimental study.AnimalsEight random‐source mixed breed dogs > 1 year old and weighing between 13 and 22 kg.MethodsWithin three anesthetic episodes, separated by at least 3 days, dogs were assigned to receive either 1 mL lidocaine 2% maxillary nerve block (ML); 0.5 mL lidocaine 2% infraorbital nerve block (IOL); or equal amounts of saline for maxillary or infraorbital nerve block combined as control treatment (S). Monitoring included temperature, respiratory rate, end‐tidal CO₂, ECG, heart rate (HR), systolic, diastolic and mean arterial pressure (SAP, DAP, MAP). Posterior (pR) and anterior rhinoscopies (aR) were performed and scored. Differences from baseline for outcome parameters HR, SAP, DAP, MAP were analyzed using repeated‐measures anova, and results reported as mean ± SD. Binary scores for rhinoscopy were analyzed using logistic regression, and odds ratio was reported.ResultsChanges from baseline for HR and SAP were significant for all treatments, besides ML for pR. Difference in changes from baseline among treatments was statistically significant for HR during pR with ML < S, and for SAP, DAP and MAP in right and left aR with ML < S and IOL > ML, except for DAP in left aR with only IOL > ML. Analysis of the binary score showed that the probability of a response for S and IOL treatments was nearly triple that of the ML treatment. None of the dogs, regardless of the treatments applied, responded to skin clamping.Conclusion and clinical relevanceCardiovascular parameters do not seem to reflect the occurrence of adverse reactions during rhinoscopy. The maxillary nerve block is superior to the infraorbital nerve block, as applied in this study, in preventing adverse reactions during posterior rhinoscopy.     

Outbreaks of renal failure associated with melamine and cyanuric acid in dogs and cats in 2004 and 2007.

Sixteen animals affected in 2 outbreaks of pet food-associated renal failure (2 dogs in 2004; 10 cats and 4 dogs in 2007) were evaluated for histopathologic, toxicologic, and clinicopathologic changes. All 16 animals had clinical and laboratory evidence of uremia, including anorexia, vomiting, lethargy, polyuria, azotemia, and hyperphosphatemia. Where measured, serum hepatic enzyme concentrations were normal in animals from both outbreaks. All animals died or were euthanized because of severe uremia. Distal tubular lesions were present in all 16 animals, and unique polarizable crystals with striations were present in distal tubules or collecting ducts in all animals. The proximal tubules were largely unaffected. Crystals and histologic appearance were identical in both outbreaks. A chronic pattern of histologic change, characterized by interstitial fibrosis and inflammation, was observed in some affected animals. Melamine and cyanuric acid were present in renal tissue from both outbreaks. These results indicate that the pet food-associated renal failure outbreaks in 2004 and 2007 share identical clinical, histologic, and toxicologic findings, providing compelling evidence that they share the same causation.