An important issue for in vivo gene therapy for cystic fibrosis (CF) is the percentage of cells within the CF airway that will require correction. In this study, we mixed populations of a CF airway cell line expressing either the normal cystic fibrosis transmembrane conductance regulator (CFTR) cDNA (corrected cells) or a reporter gene in defined percentages. As few as 6-10% corrected cells within an epithelial sheet generated C1-transport properties similar to sheets comprised of 100% corrected cells. Cell-cell coupling may serve as the mechanism for amplification of the functional effects of corrected cells. These data suggest that in vivo correction of all CF airway cells may not be mandatory.

The aims of this study were to: (i) determine the chemical composition of 11 samples of crude glycerol collected from seven Australian biodiesel manufacturers; and (ii) examine the effects of increasing levels of crude glycerol fed to growing-finishing pigs on performance, plasma metabolites and meat quality at slaughter. Chemical composition of crude glycerol samples varied considerably; glycerol content ranged between 38 and 96%, with some samples containing up to 29% ash and 14% methanol. One of these samples (76.1% glycerol, 1.83% methanol) was then fed to 64 female pigs (50.9 ± 5.55 kg; mean ± s.d.) allocated to one of five dietary treatments (0, 4, 8, 12 and 16% crude glycerol) until they reached 105 kg liveweight. There were no statistical differences in performance indices with increasing levels of added glycerol, although there was an unexpectedly high variation between treatments. Blood glycerol levels were unaffected by diet in week two of the experiment, but increased linearly (P < 0.001) with increasing levels of dietary glycerol before slaughter. The inclusion of crude glycerol did not influence any meat quality parameters at slaughter (P > 0.05). Diets containing added crude glycerol were less dusty after mixing, but diets that contained 8, 12 and 16% glycerol all formed a firm aggregate within 24 h of mixing that presented some feeding difficulties. This might restrict inclusion of glycerol in mash diets to dietary levels less than 8%. Furthermore, levels of residues such as methanol and ash should be monitored to prevent excessive amounts of these compounds in pig diets.

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Nineteen healthy volunteers ingested 400 ml black tea, coffee, caffeinated water, decaffeinated tea or plain water on three occasions through the day (0900, 1400 and 1900 hours). A 2 x 2 factorial design with caffeine (0, 100 mg) and beverage type (water, tea) was employed, with coffee (100 mg caffeine) as a positive internal control, based on a five-way crossover. A psychometric test battery comprising critical flicker fusion (CFF), choice reaction time (CRT), short-term memory (STM) and subjective sedation (LARS) was performed at regular intervals throughout the day, and intensively so immediately following each beverage. Consumption of tea compared to water was associated with transient improvements in performance (CFF) within 10 min of ingestion and was not affected by the time of day. Caffeine ingestion was associated with a rapid (10 min) and persistent reduction in subjective sedation values (LARS), again independent of time of day, but did not acutely alter CFF threshold. Over the whole day, consumption of tea rather than water, and of caffeinated compared to decaffeinated beverages, largely prevented the steady decline in alertness (LARS) and cognitive capacity observed with water ingestion. The effects of tea and coffee were similar on all measures, except that tea consumption was associated with less variation in CFF over the whole day. No significant treatment effects were apparent in the data for the STM. Tea ingestion is associated with rapid increases in alertness and information processing capacity and tea drinking throughout the day largely prevents the diurnal pattern of performance decrements found with the placebo (no caffeine) condition. It appears that the effects of tea and coffee were not entirely due to caffeine per se; other factors either intrinsic to the beverage (e.g. sensory attributes or the presence of other biologically active substances) or of a psychological nature (e.g. expectancy) are likely to play a significant role in mediating the responses observed in this study.

Use of the air-liquid interface culture technique has produced improved morphological differentiation of rodent, canine, and human tracheal epithelia. We have investigated the effect of this culture technique on ion transport activities of cultured canine bronchial epithelia. These cells were isolated from excised airways by enzymatic digestion and plated on permeable collagen membrane substrates. All cultures were maintained utilizing standard culture techniques, by bathing both apical and basolateral sides with hormone supplemented, serum-free media until confluent (days 4-6). Half of the cultures were converted to air-liquid interface cultures (ALIC) by gentle aspiration of the apical medium and half were continued under standard technique culture (STC) conditions. After three additional days, preparations cultured under both conditions were mounted in modified Ussing chambers where bioelectric properties were measured under short-circuit conditions. Mean short-circuit current (Isc) was significantly greater in ALIC (-91.3 +/- 7.84 microA/cm2) than in STC (-54.8 +/- 5.03 microA/cm2). The sodium channel blocker, amiloride, reduced Isc by 68.4 +/- 5.0% in STC and by 84.8 +/- 3.0% in ALIC. 22Na and 36Cl fluxes confirmed the presence of enhanced sodium absorption in ALIC when compared with STC. The depth of the apical fluid, measured by microelectrodes during ALIC, was approximately 15 microns. Studies of cellular metabolism demonstrated a shift in metabolism from an anaerobic to an oxidative pattern in ALIC. This change in the pattern of metabolism suggests that the ALIC technique enhanced sodium transport in canine bronchial epithelia by increasing oxygen delivery to the epithelium.