Hydrogeology of a groundwater sustained montane peatland: Grass Lake, California

Persistently wet conditions are essential to prevent the decomposition of organic material that forms peatlands. Wetlands in areas with a snow-melt dominated precipitation regime and little or no summer precipitation often rely on groundwater to meet late-season water requirements. Past and predicted changes in climate for the Sierra Nevada show a trend towards more winter precipitation falling as rain rather than snow. This is expected to result in reduced late-season water availability and the subsequent degradation of peatlands. Measurements of groundwater levels, stream flow, specific conductance, and peat water retention characteristics are used to quantify aspects of the hydrologic system that supports Grass Lake, south of Lake Tahoe California, the largest peatland in the Sierra Nevada. Water budget calculations using periodic measurements collected throughout the growing season show that groundwater discharge is a significant component of the water balance in the late-summer and fall. Late-season evapotranspiration needs were approximately balanced by groundwater inflow for 2010 (average water year). Groundwater discharge to the peatland dominated the late-season water budget in 2011 (above average water year) and persisted into October. Water retention experiments and field data suggest desaturation of the peatland accounts for approximately 0.5 mm day−1, or roughly 10 % of the estimated evapotranspiration rate

A surgical model of composite cystoplasty with cultured urothelial cells: a controlled study of gross outcome and urothelial phenotype

OBJECTIVES : To study the outcome of composite cystoplasty using cultured urothelial cells combined with de-epithelialized colon or uterus in a porcine surgical model, using appropriate controls, and to characterize the neo-epithelium created by composite cystoplasty. MATERIALS AND METHODS : Urothelial cells were isolated and propagated in vitro from open bladder biopsies taken from nine female minipigs. Cohesive sheets of confluent urothelial cells were transferred to polyglactin carrier meshes and sutured to de-epithelialized autologous colon in four animals and de-epithelialized autologous uterus in five. These composite segments were then used for augmentation cystoplasty. Conventional colocystoplasty, de-epithelialized colocystoplasty and sham operations were carried out in six control animals. After killing the animals at ≈ 90 days the bladders were removed for examination and immunohistochemical analysis, using a panel of antibodies against cytokeratins and urothelial differentiation-associated antigens. RESULTS : Macroscopically, the bladders augmented with composite segments derived from uterine muscle had no evidence of shrinkage or contracture. Histological analysis showed that in four of five composite uterocystoplasties, the neo-urothelium was stratified and had a transitional morphology, although in some areas coverage was incomplete. Immunohistochemical analysis showed evidence of squamous differentiation in both native and augmented segments. All composite and de-epithelialized colonic segments showed significant contraction with poor urothelial coverage, reflecting the unsuitability of the thin-walled porcine colon for de-epithelialization. CONCLUSIONS : The functional and macroscopic outcome of bladder augmentation with a composite derived from cultured urothelium and de-epithelialized smooth muscle of uterine origin endorses the feasibility of composite cystoplasty

Kv1.4 channel block by quinidine: evidence for a drug-induced allosteric effect

We studied quinidine block of Kv1.4ΔN, a K+ channel lacking N-type inactivation, expressed in Xenopus ooctyes. Initially, quinidine intracellularly blocked the open channel so rapidly it overlapped with activation. This rapid open channel block was reduced (non-additively) by interventions that slow C-type inactivation: [K+]o elevation and an extracellular lysine to tyrosine mutation (K532Y). These manipulations reduced the affinity of rapid open channel block ≈10-fold, but left the effective electrical distance unchanged at ≈0.15. Following rapid open channel block, there were time-dependent quinidine effects: the rate of inactivation during a single depolarisation was increased, and repetitive pulsing showed use dependence. The rate of recovery from the time-dependent aspect of quinidine block was similar to recovery from normal C-type inactivation. Manipulations that prevented the channel from entering the C-type inactivated state (i.e. high [K+]o or the K532Y mutation) prevented the development of the time-dependent quinidine-induced inactivation. The concentration dependence of the rapid block and the time-dependent quinidine-induced inactivation were similar, but the time-dependent component was strongly voltage sensitive, with an effective electrical distance of 2. Clearly, this cannot reflect the permeation of quinidine through the electric field, but must be the result of some other voltage-sensitive change in the channel. We propose that quinidine promotes the entry of the channel into a C-type inactivated state in a time- and voltage-dependent manner. We developed a mathematical model based on these results to test the hypothesis that, following rapid open channel block, quinidine promotes development of the C-type inactivated state through a voltage-dependent conformational change

Challenges in Archaeological Tourism in China

Worldwide archaeological tourism, or tourism to sites with archaeological significance, has been rapidly growing and has attracted increased academic attention in recent years. China is an outstanding case in this field. In fact, its government has been actively promoting tourism and archaeological tourism for the last three decades. The understanding of the challenges that Chinese archaeological tourism is currently facing is the focus of this article. Four aspects will guide the discussion: the dilemma between site preservation and economic profitability, unregulated tourism development, the influence of UNESCO World Heritage designation, and authorities’ sensitivity towards ethnic issues in archaeological tourism