Mucociliary clearance in patients with continuous ambulatory peritoneal dialysis.

INTRODUCTION: Mucociliary clearance (MC) is a critical defense mechanism for the protection of the entire respiratory system. Nasal colonization of some pathogens and chronical nasal infections are important risk factors for peritonitis. Any disturbance in the MC causes stasis of secretions and secondary infections. OBJECTIVE: The aim of the study was to evaluate the patients with chronic kidney disease (CKD) receiving continuous ambulatory peritoneal dialysis (CAPD) in terms of nasal MC. More specifically, the goal is to investigate the possible correlation between the nasal MC and peritonitis. METHODS: Forty CAPD patients and 39 healthy volunteers were involved in the study. The nasal MC was evaluated with the saccharin test, in which a 1mm diameter saccharin particle was carefully placed on the antero-medial surface of inferior nasal concha. The time taken by the subjects from the placement of particle to the perception of the sweet taste was taken as mucociliary clearance time (MCT). The groups were compared in terms of MCT. The patient group was evaluated in terms of a peritonitis history, and the correlations with MC were analyzed. RESULTS: Patient group with CKD consisted of 16 females and 24 males with a mean age of 32.4 years; healthy individuals in the control group consisted of 17 women and 22 men with a mean age of 33.3 years. There was not a significant difference in terms of mean MC time in patients with CKD when compared with the individuals in the control group. The comparison between the mean MCT in the patients who had a history of peritonitis and patients without peritonitis was statistically significant (p<0.05). CONCLUSIONS: Unique for being conducted with patients in continuous ambulatory peritoneal dialysis, the current study shows that although the MC of CKD patients and healthy individuals is similar, patients with low rates of MC appear to present an increased incidence of peritoneal infection. Considering the small sample investigated, an invitation to future confirmatory studies would be appropriate.

PET imaging during hypoglycaemia to study adipose tissue metabolism.

BACKGROUND: Disturbances in adipose tissue glucose uptake may play a role in the pathogenesis of type 2 diabetes, yet its examination by 2-deoxy-2-[18 F]fluorodeoxyglucose ([18 F]FDG) PET/CT is challenged by relatively low uptake kinetics. We tested the hypothesis that performing [18 F]FDG PET/CT during a hypoglycaemic clamp would improve adipose tissue tracer uptake to allow specific comparison of adipose tissue glucose handling between people with or without type 2 diabetes. DESIGN: We enrolled participants with or without diabetes who were at least overweight, to undergo a hyperinsulinaemic hypoglycaemic clamp or a hyperinsulinaemic euglycaemic clamp (n = 5 per group). Tracer uptake was quantified using [18 F]FDG PET/CT. RESULTS: Hypoglycaemic clamping increased [18 F]FDG uptake in visceral adipose tissue of healthy participants (P = 0.002). During hypoglycaemia, glucose uptake in visceral adipose tissue of type 2 diabetic participants was lower as compared to healthy participants (P < 0.0005). No significant differences were observed in skeletal muscle, liver or pancreas. CONCLUSIONS: The present findings indicate that [18 F]FDG PET/CT during a hypoglycaemic clamp provides a promising new research tool to evaluate adipose tissue glucose metabolism. Using this method, we observed a specific impairment in visceral adipose tissue [18 F]FDG uptake in type 2 diabetes, suggesting a previously underestimated role for adipose tissue glucose handling in type 2 diabetes.

Redox mediators and irradiation improve fenton degradation of acesulfame.

Widely recognized as a promising approach to degrading recalcitrant pollutants, Advanced Oxidation Processes (AOPs) have drawn much attention for their effectiveness and efficiency. Among all the AOPs, the Fenton system has been widely applied for oxidation and mineralization of micropollutants due to its ease of implementation and high catalytic efficiency. However, the necessity of preceding acidification, together with rapid consumption and slow regeneration of Fe(II) resulting in deterioration of reactivity, has reduced its competitiveness as a practical option for water treatment. Acknowledging the above drawbacks, this study investigates the potential viable option to enhance the Fenton system. Acesulfame was chosen as the model compound due to its ubiquitous occurrence and persistence in the environment. UV-assisted photo-Fenton treatment was found to remove the parent compound effectively; the transformation profile of acesulfame was identified and elucidated with the ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry. Prolonged UV photo-Fenton treatment was effective for mineralization of the majority of the transformation products, without increasing the overall toxicity as indicated by Vibrio fischeri bioluminescence assay. The positive effects of the addition of redox mediators to Fenton systems at neutral pH were confirmed in this study. The results could be the basis for further development of homogeneous catalytic degradation techniques for the oxidation of environmental contaminants at circumneutral pHs to neutral pHs.

Quantitative determination of mogroside V in rat plasma by LC-MS/MS and its application to a pharmacokinetic study.

Mogroside V is the most abundant (approximately 0.50%) cucurbitane-type triterpene glycoside in Siraitia grosvenorii and exhibits significant antitussive, expectorant, anti-carcinogenic, and anti-inflammatory effects. A sensitive, robust and selective liquid chromatography tandem with mass spectrometry (LC-MS/MS) was developed and validated for the determination and pharmacokinetic investigation of mogroside V in rat plasma. Samples were prepared through an one-step deproteinization procedure with 250 µL of methanol to a 75-µL plasma sample. Plasma samples were effectively separated on a Shiseido Capcell Pak UG120 C18 column (2.0 × 50mm, 3.0µm) using a mobile phase consisting of methanol: water (60:40, v/v) with an isocratic elution program. The running time for each sample was 7.0 min and the elution times of mogroside V and IS were 2.0 and 4.8 min, respectively. The detection relied on a triple-quadrupole tandem with mass spectrometer equipped with negative-ion electrospray ionization interface by selected-reaction monitoring (SRM) of the transitions at m/z 1285.6 → 1123.7 for mogroside V and m/z 1089.6 → 649.6 for IS. The calibration curve was linear over the range of 96.0-96000ng/mL with a limit of quantitation (LOQ) of 96.0ng/mL. Intra-day and inter-day precisions were both <10.1%. Mean recovery and matrix effect of mogroside V in plasma were in the range of 91.3-95.7% and 98.2-105.0%, respectively. This method was successfully applied in the pharmacokinetic study of mogroside V after intravenous or intraperitoneal administration of 1.12mg/kg mogroside V in rats.

Evaluation of nasal mucociliary clearance using saccharin test in smokers: A prospective study.

BACKGROUND AND AIM: Nasal mucociliary clearance time (NMCT) can be measured with the saccharine clearance test which is an inexpensive and easy method. The aim of the present study was to compare and evaluate NMCT using the saccharine clearance test in smokers and non-smokers. MATERIALS AND METHODS: Eighty-five patients whose ages ranged from 18 to 65 years were included in the study. Fifty of the patients were smokers (Group 1) while 35 were healthy, non-smoking volunteers (Group 2). Saccharin clearance test was used to evaluate NMCT in both groups. The results obtained were compared and the statistical analyses were performed using the Statistical Package for Social Sciences (SPSS). RESULTS: NMCT was statistically significantly higher in Group 1 as compared to Group 2 (P < .001, Mann-Whitney U test). However, in cumulative smoking duration (pack-year), Fagerström test values and gender categories, there was no statistically significant difference in the average NMCT values of the two groups (P = .943 vs P = .812 respectively), P = .45). CONCLUSION: Mucociliary activity, the primary defence mechanism of the respiratory epithelium, is significantly depressed in smokers. Our findings showed that the said depression is not associated with the number of cigarettes smoked, duration of smoking or nicotine dependence.

Oxidative Stress as a Mechanism Involved in Kidney Damage After Subchronic Exposure to Vanadium Inhalation and Oral Sweetened Beverages in a Mouse Model.

Kidney diseases have notably increased in the last few years. This is partially explained by the increase in metabolic syndrome, diabetes, and systemic blood hypertension. However, there is a segment of the population that has neither of the previous risk factors, yet suffers kidney damage. Exposure to atmospheric pollutants has been suggested as a possible risk factor. Air-suspended particles carry on their surface a variety of fuel combustion-related residues such as metals, and vanadium is one of these. Vanadium might produce oxidative stress resulting in the damage of some organs such as the kidney. Additionally, in countries like Mexico, the ingestion of sweetened beverages is a major issue; whether these beverages alone are responsible for direct kidney damage or whether their ingestion promotes the progression of an existing renal damage generates controversy. In this study, we report the combined effect of vanadium inhalation and sweetened beverages ingestion in a mouse model. Forty CD-1 male mice were distributed in 4 groups: control, vanadium inhalation, 30% sucrose in drinking water, and vanadium inhalation plus sucrose 30% in drinking water. Our results support that vanadium inhalation and the ingestion of 30% sucrose induce functional and histological kidney damage and an increase in oxidative stress biomarkers, which were higher in the combined effect of vanadium plus 30% sucrose. The results also support that the ingestion of 30% sucrose alone without hyperglycemia also produces kidney damage.

Torsemide Fast Dissolving Tablets: Development, Optimization Using Box-Bhenken Design and Response Surface Methodology, In Vitro Characterization, and Pharmacokinetic Assessment.

The present study planed to develop new fast dissolving tablets (FDTs) of torsemide. Solid dispersions (SDs) of torsemide and sorbitol (3:1) or polyvinylpyrrolidone (PVP) k25 were prepared. The prepared SDs were evaluated for in-vitro dissolution. Fourier transform infrared spectroscopy and differential scanning calorimetry for SDs revealed no drug/excipient interactions and transformation of torsemide to the amorphous form. Torsemide/sorbitol SD was selected for formulation of torsemide FDTs by direct compression method. Box-Bhenken factorial design was employed to design 15 formulations using croscarmellose sodium and crospovidone at different concentrations. The response surface methodology was used to analyze the effect of changing these concentrations (independent variables) on disintegration time (Y1), percentage friability (Y2), and amount torsemide released at 10 min. The physical mixtures of torsemide and the used excipients were evaluated for angle of repose, Hausner's ratio, and Carr's index. The prepared FDTs tablets were evaluated for wetting and disintegration time, weight variation, drug content, percentage friability, thickness, hardness, and in vitro release. Based on the in-vitro results and factorial design characterization, F10 and F7 were selected for bioavailability studies following administration to Albino New Zealand rabbits. They showed significantly higher C max and (AUC0-12) and shorter T max than those obtained after administration of the corresponding ordinary commercial Torseretic ® tablets. Stability study was conducted for F10 that showed good stability upon storage at 30°C/75% RH and 40°C/75% RH for 3 months.

Biological fate of low-calorie sweeteners.

With continued efforts to find solutions to rising rates of obesity and diabetes, there is increased interest in the potential health benefits of the use of low- and no-calorie sweeteners (LNCSs). Concerns about safety often deter the use of LNCSs as a tool in helping control caloric intake, even though the safety of LNCS use has been affirmed by regulatory agencies worldwide. In many cases, an understanding of the biological fate of the different LNSCs can help health professionals to address safety concerns. The objectives of this review are to compare the similarities and differences in the chemistry, regulatory status, and biological fate (including absorption, distribution, metabolism, and excretion) of the commonly used LNCSs: acesulfame potassium, aspartame, saccharin, stevia leaf extract (steviol glycoside), and sucralose. Understanding the biological fate of the different LNCSs is helpful in evaluating whether reports of biological effects in animal studies or in humans are indicative of possible safety concerns. Illustrations of the usefulness of this information to address questions about LNCSs include discussion of systemic exposure to LNCSs, the use of sweetener combinations, and the potential for effects of LNCSs on the gut microflora.

Sucralose Non-Carcinogenicity: A Review of the Scientific and Regulatory Rationale.

Regulatory authorities worldwide have found the nonnutritive sweetener, sucralose, to be noncarcinogenic, based on a range of studies. A review of these and other studies found through a comprehensive search of electronic databases, using appropriate key terms, was conducted and results of that review are reported here. An overview of the types of studies relied upon by regulatory agencies to assess carcinogenicity potential is also provided as context. Physiochemical and pharmacokinetic/toxicokinetic studies confirm stability under conditions of use and reveal no metabolites of carcinogenic potential. In vitro and in vivo assays reveal no confirmed genotoxic activity. Long-term carcinogenicity studies in animal models provide no evidence of carcinogenic potential for sucralose. In studies in healthy adults, sucralose was well-tolerated and without evidence of toxicity or other changes that might suggest a potential for carcinogenic effects. In summary, sucralose does not demonstrate carcinogenic activity even when exposure levels are several orders of magnitude greater than the range of anticipated daily ingestion levels.

Dexamethasone reverses the effects of high glucose on human retinal endothelial cell permeability and proliferation in vitro.

Diabetic macular oedema (DMO), a leading cause of preventable visual loss in the working population, is caused by an increase in microvascular endothelial cell permeability, and its prevalence is on the increase in parallel with the rising worldwide prevalence of diabetes. It is known that retinal vascular leakage in DMO is contributed to by VEGF upregulation as well as non-VEGF dependent inflammatory pathways, and the potential use of anti-inflammatory agents such as the glucocorticoids, including dexamethasone are being extensively studied. However, the mechanisms of action of dexamethasone in DMO reduction are not fully understood. Using human primary retinal endothelial cells (REC) the in vitro effect of dexamethasone in modulating the proliferation, permeability and gene expression of key tight and adheren junction components, and the expression of angiopoietins (Ang) 1 and 2 in high (25 mM) glucose conditions were investigated. High glucose decreased REC proliferation, an effect that was reversed by dexamethasone. High glucose conditions significantly increased REC permeability and decreased claudin-5, occludin and JAM-A gene expression; dexamethasone was effective in partially reversing these changes, restoring EC permeability to the normal or near normal state. High glucose levels resulted in reduction of Ang1 secretion, although Ang2 levels were consistently high. DEX increased Ang1 and decreased Ang2, indicating that the balance of Ang1/Ang2 may be important in determining functional changes in REC under high glucose conditions.

Occurrence of artificial sweeteners in human liver and paired blood and urine samples from adults in Tianjin, China and their implications for human exposure.

In this study, acesulfame (ACE), saccharin (SAC) and cyclamate (CYC) were found in all paired urine and blood samples collected from healthy adults, with mean values of 4070, 918 and 628 ng mL(-1), respectively, in urine and 9.03, 20.4 and 0.72 ng mL(-1), respectively, in blood. SAC (mean: 84.4 ng g(-1)) and CYC (4.29 ng g(-1)) were detectable in all liver samples collected from liver cancer patients, while ACE was less frequently detected. Aspartame (ASP) was not found in any analyzed human sample, which can be explained by the fact that this chemical metabolized rapidly in the human body. Among all adults, significantly positive correlations between SAC and CYC levels were observed (p < 0.001), regardless of human matrices. Nevertheless, no significant correlations between concentrations of SAC (or CYC) and ACE were found in any of the human matrices. Our results suggest that human exposure to SAC and CYC is related, whereas ACE originates from a discrete source. Females (or young adults) were exposed to higher levels of SAC and CYC than males (or elderly). The mean renal clearance of SAC was 730 mL per day per kg in adults, which was significantly (p < 0.001) lower than those for CYC (10 800 mL per day per kg) and ACE (10 300 mL per day per kg). The average total daily intake of SAC and ACE was 9.27 and 33.8 µg per kg bw per day, respectively.

Chemical-specific adjustment factors (inter-species toxicokinetics) to establish the ADI for steviol glycosides.

The acceptable daily intake (ADI) of commercially available steviol glycosides is currently 0-4 mg/kg body weight (bw)/day, based on application of a 100-fold uncertainty factor to a no-observed-adverse-effect-level value from a chronic rat study. Within the 100-fold uncertainty factor is a 10-fold uncertainty factor to account for inter-species differences in toxicokinetics (4-fold) and toxicodynamics (2.5-fold). Single dose pharmacokinetics of stevioside were studied in rats (40 and 1000 mg/kg bw) and in male human subjects (40 mg/kg bw) to generate a chemical-specific, inter-species toxicokinetic adjustment factor. Tmax values for steviol were at ∼8 and ∼20 h after administration in rats and humans, respectively. Peak concentrations of steviol were similar in rats and humans, while steviol glucuronide concentrations were significantly higher in humans. Glucuronidation in rats was not saturated over the dose range 40-1000 mg/kg bw. The AUC0-last for steviol was approximately 2.8-fold greater in humans compared to rats. Chemical-specific adjustment factors for extrapolating toxicokinetics from rat to human of 1 and 2.8 were established based on Cmax and AUC0-last data respectively. Because these factors are lower than the default value of 4.0, a higher ADI for steviol glycosides of between 6 and 16 mg/kg bw/d is justified.

[FREE CONSUMPTION OF GLUCOSE SOLUTION BY RATS AS A CRITERION FOR EVALUATION ITS ABSORPTION IN THE SMALL INTESTINE (Experimental study and mathematical modeling)].

The aim of the work is to analyze the relationship between consumption of glucose solution by rats and its absorption, and to use this fact for assessment of the absorptive capacity of the small intestine in non anesthetized animals in vivo. Consumption of glucose solution (200 g/l) by fasted rats was recorded in the control, and after administration of phloridzin--inhibitor of glucose active transport- or 3 hours after the restriction stress. On the mathematical model we studied the relative role of factors that can influence the temporal dynamics of glucose consumption by rats. The rate of glucose consumption was observed being decreased in the presence of phloridzin (1 mM), and be increased after the stress. The results of modeling are consistent with the experimental data and show that the rate of consumption of glucose solutions considerably more depends on the transport activity of the small intestine than on glucose concentration in the solution, or on the substrate regulation of the stomach emptying. Analysis of dynamics of consumption of glucose solution by intact rats may be considered as one of promising approaches to assessing the absorptive capacity of the small intestine under natural conditions.

Exploring in vitro, in vivo metabolism of mogroside V and distribution of its metabolites in rats by HPLC-ESI-IT-TOF-MS(n).

Mogroside V, a cucurbitane-type saponin, is not only the major bioactive constituent of traditional Chinese medicine Siraitiae Fructus, but also a widely used sweetener. To clarify its biotransformation process and identify its effective forms in vivo, we studied its metabolism in a human intestinal bacteria incubation system, a rat hepatic 9000g supernatant (S9) incubation system, and rats. Meanwhile, the distribution of mogroside V and its metabolites was also reported firstly. Seventy-seven new metabolites, including 52 oxidation products formed by mono- to tetra- hydroxylation/dehydrogenation, were identified with the aid of HPLC in tandem with ESI ion trap (IT) TOF multistage mass spectrometry (HPLC-ESI-IT-TOF-MS(n)). Specifically, 14 metabolites were identified in human intestinal bacteria incubation system, 4 in hepatic S9 incubation system, 58 in faeces, 29 in urine, 14 in plasma, 34 in heart, 33 in liver, 39 in spleen, 39 in lungs, 42 in kidneys, 45 in stomach, and 51 in small intestine. The metabolic pathways of mogroside V were proposed and the identified metabolic reactions were deglycosylation, hydroxylation, dehydrogenation, isomerization, glucosylation, and methylation. Mogroside V and its metabolites were distributed unevenly in the organs of treated rats. Seven bioactive metabolites of mogroside V were identified, among which mogroside IIE was abundant in heart, liver, spleen and lung, suggesting that it may contribute to the bioactivities of mogroside V. Mogroside V was mainly excreted in urine, whereas its metabolites were mainly excreted in faeces. To our knowledge, this is the first report that a plant constituent can be biotransformed into more than 65 metabolites in vivo. These findings will improve understanding of the in vivo metabolism, distribution, and effective forms of mogroside V and congeneric molecules.

Aspartame sensitivity? A double blind randomised crossover study.

BACKGROUND: Aspartame is a commonly used intense artificial sweetener, being approximately 200 times sweeter than sucrose. There have been concerns over aspartame since approval in the 1980s including a large anecdotal database reporting severe symptoms. The objective of this study was to compare the acute symptom effects of aspartame to a control preparation. METHODS: This was a double-blind randomized cross over study conducted in a clinical research unit in United Kingdom. Forty-eight individual who has self reported sensitivity to aspartame were compared to 48 age and gender matched aspartame non-sensitive individuals. They were given aspartame (100mg)-containing or control snack bars randomly at least 7 days apart. The main outcome measures were acute effects of aspartame measured using repeated ratings of 14 symptoms, biochemistry and metabonomics. RESULTS: Aspartame sensitive and non-sensitive participants differed psychologically at baseline in handling feelings and perceived stress. Sensitive participants had higher triglycerides (2.05 ± 1.44 vs. 1.26 ± 0.84mmol/L; p value 0.008) and lower HDL-C (1.16 ± 0.34 vs. 1.35 ± 0.54 mmol/L; p value 0.04), reflected in 1H NMR serum analysis that showed differences in the baseline lipid content between the two groups. Urine metabonomic studies showed no significant differences. None of the rated symptoms differed between aspartame and control bars, or between sensitive and control participants. However, aspartame sensitive participants rated more symptoms particularly in the first test session, whether this was placebo or control. Aspartame and control bars affected GLP-1, GIP, tyrosine and phenylalanine levels equally in both aspartame sensitive and non-sensitive subjects. CONCLUSION: Using a comprehensive battery of psychological tests, biochemistry and state of the art metabonomics there was no evidence of any acute adverse responses to aspartame. This independent study gives reassurance to both regulatory bodies and the public that acute ingestion of aspartame does not have any detectable psychological or metabolic effects in humans. TRIAL REGISTRATION: ISRCTN Registry ISRCTN39650237.

Enhanced water and cryoprotectant permeability of porcine oocytes after artificial expression of human and zebrafish aquaporin-3 channels.

One of the major obstacles for the vitrification of mature porcine oocytes with ethylene glycol is their low permeability to this cryoprotectant, which results in osmotic stress-induced cell damage and low survival. Pig blastocysts, on the other hand, show enhanced water and cryoprotectant permeability, which has been related to the transcriptional activation of aquaporin-3 (AQP3) channels at this stage of development. In this study, we asked if expression of cRNAs encoding two aquaglyceroporins, human AQP3 (hAQP3) or the zebrafish Aqp3b-T85A mutant, in porcine oocytes can increase their permeability. Microinjection of germinal-vesicle-stage oocytes with enhanced green fluorescent protein (EGFP) or AQP3 cRNAs resulted in the expression of the corresponding proteins in ∼26% of the metaphase-II stage oocytes at 40-44 hr of in vitro culture; co-injection of EGFP cRNA appeared to be a suitable marker for oocyte selection since all EGFP-positive oocytes also expressed the corresponding aquaporin. Using this method, we found that mature oocytes co-expressing EGFP and hAQP3 or EGFP and Aqp3b-T85A showed approximately a twofold increase of the hydraulic conductivity (Lp ) with respect non-injected or EGFP alone-injected oocytes in a 0.43 M sucrose or 1.3 M ethylene glycol solution, whereas the ethylene glycol permeability (PEG ) of EGFP + hAQP3 and EGFP + Aqp3b-T85A oocytes was 6.7- and 12-fold higher, respectively, than control oocytes. These data demonstrate that the artificial expression of aquaglyceroporins in porcine metaphase-II oocytes improves their permeability, and that the zebrafish Aqp3b-T85A mutant is more efficient than the human channel at increasing the oocyte permeability to ethylene glycol.

Glucose-induced temporary visual recovery in primary open-angle glaucoma: a double-blind, randomized study.

PURPOSE: To investigate the effect of topical glucose on visual parameters in individuals with primary open-angle glaucoma (POAG). DESIGN: Double-blind, randomized, crossover study. PARTICIPANTS: Nondiabetic pseudophakic patients with definite POAG were recruited; 29 eyes of 16 individuals participated in study 1. A follow-up study (study 2) included 14 eyes of 7 individuals. INTERVENTION: Eyes were randomly allocated to receive 50% glucose or saline eye drops every 5 minutes for 60 minutes. MAIN OUTCOME MEASURES: The contrast sensitivity and best-corrected logarithm of the minimum angle of resolution (logMAR). RESULTS: The 50% glucose reached the vitreous in pseudophakic but not phakic individuals. Glucose significantly improved the mean contrast sensitivity at 12 cycles/degree compared with 0.9% saline by 0.26 log units (95% confidence interval [CI], 0.13-0.38; P < 0.001) and 0.40 log units (95% CI, 0.17-0.60; P < 0.001) in the follow-up study. The intraocular pressure, refraction, and central corneal thickness were not affected by glucose; age was not a significant predictor of the response. CONCLUSIONS: Topical glucose temporarily improves psychophysical visual parameters in some individuals with POAG, suggesting that neuronal energy substrate delivery to the vitreous reservoir may recover function of "sick" retinal neurons.

A microdevice for parallelized pulmonary permeability studies.

We describe a compartmentalized microdevice specifically designed to perform permeability studies across a model of lung barrier. Epithelial cell barriers were reproduced by culturing Calu-3 cells at the air-liquid interface (AIC) in 1 mm² microwells made from a perforated glass slide with an embedded porous membrane. We created a single basolateral reservoir for all microwells which eliminated the need to renew the growth medium during the culture growth phase. To perform drug permeability studies on confluent cell layers, the cell culture slide was aligned and joined to a collection platform consisting in 35 µL collection reservoirs connected at the top and bottom with microchannels. The integrity and functionality of the cell barriers were demonstrated by measurement of trans-epithelial electrical resistance (TEER), confocal imaging and permeability assays of ¹4C-sucrose. Micro-cell barriers were able to form confluent layers in 1 week, demonstrating a similar bioelectrical evolution as the Transwell systems used as controls. Tight junctions were observed throughout the cell-cell interfaces, and the low permeability coefficients of ¹4C-sucrose confirmed their functional presence, creating a primary barrier to the diffusion of solutes. This microdevice could facilitate the monitoring of biomolecule transport and the screening of formulations promoting their passage across the pulmonary barrier, in order to select candidates for pulmonary administration to patients.

Artificial sweeteners stimulate adipogenesis and suppress lipolysis independently of sweet taste receptors.

G protein-coupled receptors mediate responses to a myriad of ligands, some of which regulate adipocyte differentiation and metabolism. The sweet taste receptors T1R2 and T1R3 are G protein-coupled receptors that function as carbohydrate sensors in taste buds, gut, and pancreas. Here we report that sweet taste receptors T1R2 and T1R3 are expressed throughout adipogenesis and in adipose tissues. Treatment of mouse and human precursor cells with artificial sweeteners, saccharin and acesulfame potassium, enhanced adipogenesis. Saccharin treatment of 3T3-L1 cells and primary mesenchymal stem cells rapidly stimulated phosphorylation of Akt and downstream targets with functions in adipogenesis such as cAMP-response element-binding protein and FOXO1; however, increased expression of peroxisome proliferator-activated receptor γ and CCAAT/enhancer-binding protein α was not observed until relatively late in differentiation. Saccharin-stimulated Akt phosphorylation at Thr-308 occurred within 5 min, was phosphatidylinositol 3-kinase-dependent, and occurred in the presence of high concentrations of insulin and dexamethasone; phosphorylation of Ser-473 occurred more gradually. Surprisingly, neither saccharin-stimulated adipogenesis nor Thr-308 phosphorylation was dependent on expression of T1R2 and/or T1R3, although Ser-473 phosphorylation was impaired in T1R2/T1R3 double knock-out precursors. In mature adipocytes, artificial sweetener treatment suppressed lipolysis even in the presence of forskolin, and lipolytic responses were correlated with phosphorylation of hormone-sensitive lipase. Suppression of lipolysis by saccharin in adipocytes was also independent of T1R2 and T1R3. These results suggest that some artificial sweeteners have previously uncharacterized metabolic effects on adipocyte differentiation and metabolism and that effects of artificial sweeteners on adipose tissue biology may be largely independent of the classical sweet taste receptors, T1R2 and T1R3.

Effects of cigarette smoking intensity on the mucociliary clearance of active smokers.

BACKGROUND: Smoking impairs mucociliary clearance and increases respiratory infection frequency and severity in subjects with and without smoking-related chronic lung diseases. OBJECTIVE: This study evaluated the effects of smoking intensity on mucociliary clearance in active smokers. METHODS: Seventy-five active smokers were grouped into light (1-10 cigarettes/day; n = 14), moderate (11-20 cigarettes/day; n = 34) and heavy smokers (≥21 cigarettes/day; n = 27) before starting a smoking cessation programme. Smoking behaviour, nicotine dependence, pulmonary function, carbon monoxide in exhaled air (exCO), carboxyhaemoglobin (COHb) and mucociliary clearance measured by the saccharin transit time (STT) test were all evaluated. An age-matched non-smoker group (n = 24) was assessed using the same tests. RESULTS: Moderate (49 ± 7 years) and heavy smokers (46 ± 8 years) had higher STT (p = 0.0001), exCO (p < 0.0001) and COHb (p < 0.0001) levels compared with light smokers (51 ± 15 years) and non-smokers (50 ± 11 years). A positive correlation was observed between STT and exCO (r = 0.4; p < 0.0001), STT and cigarettes/day (r = 0.3, p = 0.02) and exCO and cigarettes/day (r = 0.3, p < 0.01). CONCLUSION: Smoking impairs mucociliary clearance and is associated with cigarette smoking intensity.