Reaction mechanism of surfactant‐sensitized chemiluminescence of bis(2,4,6‐trichlorophyenyl) oxalate and hydrogen peroxide induced by gold nanoparticles

The chemiluminescence (CL) of bis(2,4,6‐trichlorophyenyl) oxalate with hydrogen peroxide in the present of cationic surfactant and gold nanoparticles was studied. The CL emission was obviously enhanced in the presence of surfactant at a suitable concentration, with a synergetic catalysis effect exhibited. Different sizes of gold nanoparticles (15 and 50 nm) showed different effects on CL intensity. Mechanisms of the CL reaction and sensitization effect are discussed. Copyright © 2008 John Wiley & Sons, Ltd.     

LEAF CAVITY SIZE DIFFERENTIATION AND WATER RELATIONS IN CAREX ELEOCHARIS

Carex eleocharis leaves contain large intercellular cavities that traverse the length of the leaf above rows of stomata and are roughly constant in size throughout a leaf. Semithin sections (1–2 μm) demonstrate that the substomatal chambers are directly continuous with the intercellular cavities. Leaves of plants inhabiting moist swale regions of the shortgrass steppe, in northeastern Colorado, were found to have larger cavities as compared to leaves of plants inhabiting dry hilltops. Plants collected from a common hilltop site were grown in a controlled environment chamber, and, by manipulating the watering schedule, we obtained water potentials similar to those in the field. Leaves of “well-watered” plants were found to have larger intercellular cavities as compared to “water-stressed” plants. Leaf mesophyll cell sizes did not differ significantly between “well-watered” and “water-stressed” plants, suggesting that cavity size differences are not the result of developmental differences. Leaf cavities were shown to contain gases and to occur along the leaf length above rows of stomata. Additionally, the cavities in unstressed plants were continuous with substomal chambers. It is proposed that the reduction of cavity size is a mechanism to reduce water loss from the leaves during periods of plant water stress.     

Interspecific dominance and the foraging behaviour of juncos

We observed mixed groups of dark-eyed juncos (Junco hyemalis) and grey-headed juncos (Junco caniceps) at baited sites in northern Arizona during the non-breeding season. In interspecific and inter-racial conflicts, J. caniceps dorsalis was dominant to J. caniceps caniceps and to two races of dark-eyed juncos. Junco caniceps dorsalis also fed significantly faster than any of the other juncos. For both species, feeding rates were approximately the same in large and small mixed-species groups, though in larger groups, individual grey-headed juncos won conflicts at a higher rate and individual dark-eyed juncos lost conflicts at a higher rate. Also, dark-eyed juncos fed at a significantly lower rate in groups comprised mostly of grey-headed juncos than in groups of similar size but composed mostly of conspecifics. Residency times and recapture probabilities were similar for the two species, suggesting little difference in over-winter survival.     

Expression, regulation, and function of P2X4 purinergic receptor in human cervical epithelial cells

Micromolarconcentrations of ATP stimulate biphasic change in transepithelialconductance across CaSki cultures on filters, an acute transientincrease (phase I response; triggered by P2Y₂ receptor and mediated by calcium mobilization-dependent cell volume decrease) followed by a slower decrease in permeability (phase II response). Phase II response is mediated byaugmented calcium influx and protein kinase C-dependent increase intight junctional resistance. The objective of the study was todetermine the role of P2X₄ receptor as a mediator ofphase II response. Human cervical epithelial cells expressP2X₄ receptor mRNA (1.4-, 2.2-, and 4.4-kb isoforms byNorthern blot analysis) and P2X₄ protein. Depletion ofvitamin A reversibly downregulated P2X₄ receptor mRNA andprotein and ATP-induced calcium influx. Depletion of vitamin Aabrogated phase II response, and the effect could bepartially reversed only with retinoic acid receptor (RAR)-selectiveretinoids but not retinoid X receptor (RXR) agonists. Depletion ofvitamin A also abrogated protein kinase C increase in tight junctionalresistance, and the effect could not be reversed with retinoids.Depletion of vitamin A also abrogated phase I increase inpermeability and reversibly downregulated P2Y₂ receptormRNA and ATP-induced calcium mobilization. However, in contrast tophase II response, both RAR and RXR agonists could fullyreverse those effects. These results suggest that phase IIresponse is mediated by a P2X₄ receptor mechanism.

     

Therapeutic efficacy of Stephania tetrandra S. Moore for treatment of neovascularization of retinal capillary (retinopathy) in diabetes--in vitro study.

The present study was designed to examine therapeutic efficacy of the root extract of Stephania Tetrandra S. Moore (STMS) (traditional Chinese medicine; Han Fang Ji) for treatment of neovascularization of the retinal capillary (retinopathy) in streptozotocin (STZ)-induced diabetic rats (STZ diabetic rats) in culture. Recently we have established the culture system in which fetal bovine serum (FBS) in Dulbecco modified Eagle medium (DMEM) induced neovascularization of the retinal capillary and choroidal capillary in normal rats in culture. STZ diabetic rats showed more neovascularization of the retinal capillary and choroidal capillary than did normal rats in culture. In this study, the retinal tissue was removed for the posterior ocular region and cultured in DMEM containing FBS. The choroidal tissue of the posterior ocular region was also removed and cultured as an internal reference. Administration of STSM (0.91, 9.1 and 91 microg/ml) significantly suppressed neovascularization of the retinal capillary in both STZ diabetic rats and normal rats in a dose-dependent manner. Similar results were obtained with the choroidal capillary; administration of STSM suppressed neovascularization of the choroidal capillary in both STZ diabetic rats and normal rats. In order to determine the component of STSM inhibiting neovascularization of the retinal capillary, tetrandrine (a major chemical constituent of STSM) was administered and neovascularization of the retinal capillary was examined in culture. The effect of tetrandrine on the choroidal capillary was also examined as an internal reference. Administration of tetrandrine (0.1, 1.0 and 10 microM) suppressed neovascularization of the retinal capillary in both STZ diabetic rats and normal rats in a dose-dependent manner. Similar results were obtained with the choroidal capillary of both STZ diabetic rats and normal rats. We infer, therefore, that STSM has a direct effect on the retinal capillary of posterior ocular region and suppresses neovascularization of retinal capillary in STZ diabetic rats through the activation of tetrandrine. These results suggest that STSM may prevent for delay the progression of retinopathy in diabetic patients.