ENaC-mediated alveolar fluid clearance and lung fluid balance depend on the channel-activating protease 1.

Sodium transport via epithelial sodium channels (ENaC) expressed in alveolar epithelial cells (AEC) provides the driving force for removal of fluid from the alveolar space. The membrane-bound channel-activating protease 1 (CAP1/Prss8) activates ENaC in vitro in various expression systems. To study the role of CAP1/Prss8 in alveolar sodium transport and lung fluid balance in vivo, we generated mice lacking CAP1/Prss8 in the alveolar epithelium using conditional Cre-loxP-mediated recombination. Deficiency of CAP1/Prss8 in AEC induced in vitro a 40% decrease in ENaC-mediated sodium currents. Sodium-driven alveolar fluid clearance (AFC) was reduced in CAP1/Prss8-deficient mice, due to a 48% decrease in amiloride-sensitive clearance, and was less sensitive to beta(2)-agonist treatment. Intra-alveolar treatment with neutrophil elastase, a soluble serine protease activating ENaC at the cell surface, fully restored basal AFC and the stimulation by beta(2)-agonists. Finally, acute volume-overload increased alveolar lining fluid volume in CAP1/Prss8-deficient mice. This study reveals that CAP1 plays a crucial role in the regulation of ENaC-mediated alveolar sodium and water transport and in mouse lung fluid balance.

Dietary interventions affecting chylomicron and chylomicron remnant clearance

Interest in effects of diet on postprandial lipoproteins has increased in recent years as a result of accumulating evidence for adverse cardiovascular consequences of elevated concentrations of triglyceride rich lipoproteins. Particular attention has been given to ability of different fatty acids to modulate postprandial lipoprotein responses because of evidence for both harmful and protective cardiovascular properties of the saturated, monounsaturated and ω-6 and ω-3 polyunsaturated fatty acid (PUFA) classes. Evidence for direct atherogenic properties of chylomicron remnants has led to attempts to monitor effects of diet specifically on this lipoprotein class. Limitations in the methods employed to measure chylomicron remnants and the small number of human studies which have evaluated effects of meal, and background diet, fatty acid composition, makes it difficult to draw definitive conclusions at the present time. However consideration of data from both animal and human studies tends to support the conclusion that diets, and meals, rich in PUFA (particularly long chain ω-3 PUFA), result in attenuated postprandial responses of the intestinally-derived lipoproteins. Attenuated responses to high PUFA meals appear to be due to greater rates of clearance and greater activation of lipoprotein lipase (LPL). Attenuated responses to high PUFA background diets may be due to adaptive changes involving both accelerated rates of clearance in peripheral tissues and liver, as well as decreased output of the competitor for chylomicron clearance, very low density lipoprotein (VLDL).

Short terms effects of air pollution from biomass burning in mucociliary clearance of Brazilian sugarcane cutters

Nasal mucociliary system is the first line of defense of the upper airways and may be affected acutely by exposure to particulate matter (PM) from biomass burning. Several epidemiologic studies have demonstrated a consistent association between levels of air pollution from biomass burning with increases in hospitalization for respiratory diseases and mortality. To determine the acute effects of exposure to particulate matter from biomass burning in nasal mucociliary transport by saccharin transit time (STT) test, we studied thirty-three non-smokers and twelve light smokers sugarcane cutters in two periods: pre-harvest season and 4 h after harvest at the first day after biomass burning. Lung function, exhaled carbon monoxide (CO), nasal symptoms questionnaire and mucociliary clearance (MC) were assessed. Exhaled CO was increased in smokers compared to non-smokers but did not change significantly after harvest. In contrast, SIT was similar between smokers and non-smokers and decreased significantly after harvest in both groups (p < 0.001). Exposure to PM from biomass burning did not influence nasal symptoms. Our results suggest that acute exposure to particulate matter from sugarcane burned affects mucociliary clearance in smokers and non-smokers workers in the absence of symptoms. (C) 2011 Elsevier Ltd. All rights reserved.

Short terms effects of air pollution from biomass burning in mucociliary clearance of Brazilian sugarcane cutters

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Mucociliary clearance and its relation with the level of physical activity in daily life in healthy smokers and nonsmokers

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Reversibility of impaired nasal mucociliary clearance in smokers following a smoking cessation programme

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A model to predict R134a refrigerant leakage through the radial clearance of rolling piston compressors

In this paper a non-isothermal two-phase model for oil-R134a refrigerant mixture flow is presented to predict the R134a leakage through the radial clearance of rolling piston compressors. The flow is divided in a liquid single-phase region and in a two-phase region, in which the homogeneous model is used to simulate the flow. The refrigerant leakage is determined using the mixture mass flow rate and the refrigerant mass fraction variation along the flow. The results are obtained for inlet pressures varying from 200 to 700 kPa, inlet temperatures ranging from 40 to 60 degrees C, and minimal clearances between 10 and 60 mu m. The results are firstly compared to existing isothermal model data, showing that there is a significant difference between the leakage flow rates predicted by isothermal and non-isothermal models. Finally, a useful general equation for compressor designers is proposed to calculate the refrigerant leakage for a large range of operation conditions. (C) 2012 Elsevier Ltd and IIR. All rights reserved.

Effect of fractional urea clearance on survival of hemodialysis patients in relation to gender

Many studies have demonstrated the relationship between dialysis dose and survival. Global mortality is similar among men and women; however, the influence of dialysis dose in the survival could be more intensive between women. Therefore, we conduct an observational study to evaluate the gender-related impact of single pool Kt/V (spKt/V) on the survival of patients submitted to hemodialysis in a university hospital. We found that survival was lower in groups with spKt/V smaller than 1.2 than in those with Kt/V between 1.2 and 1.4. Among female patients, spKt/V smaller than 1.2 had a more adverse effect in survival than among men with a comparable Kt/V. Otherwise, among women, the dialysis dose had an impact in survival even with Kt/V greater than 1.4. Thus, fractional urea clearance more heavily influenced the survival of females than males in hemodialysis patients.

RESISTANCE OF TRYPANOSOMA-CRUZI TO BLOOD CLEARANCE INDUCED BY ACUTE-PHASE IMMUNE MOUSE SERUM

To investigate functional changes in Trypanosoma cruzi parasites induced during their interaction with the vertebrate host, we compared the blood clearance profiles of blood forms isolated from infected normal mice (Reg-Tc) or from infected mice immunodepressed after treatment with cyclophosphamide (Cy-Tc). Parasite blood numbers were measured at various time intervals in animals injected intravenously (i.v.) with 1-2 x 10(6) T. cruzi of either isolate. In the absence of added immune sera (spontaneous clearance), Reg-Tc and Cy-Tc were cleared from blood at similar rates. However, when acute immune mouse serum (Ac-IMS) was injected i.v. 2 min after inoculation of parasites, a significant proportion of Cy-Tc only was cleared from the blood an hour later, whereas Reg-Tc were not, their clearance profile being identical to that observed in mice injected with normal mouse serum. Cy-Tc susceptibility to Ac-IMS was not the result of a toxic effect of cyclophosphamide over T. cruzi as parasites recovered from animals immunodepressed by irradiation before infection were cleared similarly by acute serum. Contrary to Ac-IMS, chronic immune mouse serum induced similar rates of disappearance of Reg-Tc and Cy-Tc from blood. Our results suggest the occurrence of T. cruzi selection or modification during the acute phase, which leads to an increased parasite resistance to the clearance properties of acute-phase antibodies.

Pharyngeal clearance and pharyngeal transit time determined by a biomagnetic method in normal humans

Clearance and transit time are parameters of great value in studies of digestive transit. Such parameters are nowadays obtained by means of scintigraphy and videofluoroscopy, with each technique having advantages and disadvantages. In this study we present a new, noninvasive method to study swallowing pharyngeal clearance (PC) and pharyngeal transit time (PTT). This new method is based on variations of magnetic flux produced by a magnetic bolus passing through the pharynx and detected by an AC biosusceptometer (ACB). These measurements may be performed in a simple way. cause no discomfort. and do not use radiation. We measured PC in 8 volunteers (7 males and I female. 23-33 years old) and PTT in 8 other volunteers (7 males and I female. 21-29 years old). PC was 0.82 +/- 0.10 s (mean +/- SD) and PTT was 0.75 +/- 0.03 s. The results were similar for PC but longer for PTT than those determined by means of other techniques. We conclude that the biomagnetic method can be used to evaluate PC and PTT.

Transient flow of the oil-refrigerant mixture through the radial clearance in rolling piston compressors

Unsteady flow of oil and refrigerant gas through radial clearance in rolling piston compressors has been modeled as a heterogeneous mixture, where the properties are determined from the species conservation transport equation coupled with momentum and energy equations. Time variations of pressure, tangential velocity of the rolling piston and radial clearance due to pump setting have been included in the mixture flow model. Those variables have been obtained by modeling the compression process, rolling piston dynamics and by using geometric characteristics of the pump, respectively. An important conclusion concerning this work is the large variation of refrigerant concentration in the oil-filled radial clearance during the compression cycle. That is particularly true for large values of mass flow rates, and for those cases the flow mixture cannot be considered as having uniform concentration. In presence of low mass flow rates homogeneous flow prevail and the mixture tend to have a uniform concentration. In general, it was observed that for calculating the refrigerant mass flow rate using the difference in refrigerant concentration between compression and suction chambers, a time average value for the gas concentration should be used at the clearance inlet.

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. Copyright © 2013 S. Karger AG, Basel.