The effects of salbutamol on epithelial ion channels depend on the etiology of acute respiratory distress syndrome but not the route of administration

Introduction

We investigated the effects of intravenous and intratracheal administration of salbutamol on lung morphology and function, expression of ion channels, aquaporin, and markers of inflammation, apoptosis, and alveolar epithelial/endothelial cell damage in experimental pulmonary (p) and extrapulmonary (exp) mild acute respiratory distress syndrome (ARDS).

Methods

In this prospective randomized controlled experimental study, 56 male Wistar rats were randomly assigned to mild ARDS induced by either intratracheal (n = 28, ARDSp) or intraperitoneal (n = 28, ARDSexp) administration of E. coli lipopolysaccharide. Four animals with no lung injury served as controls (NI). After 24 hours, animals were anesthetized, mechanically ventilated in pressure-controlled mode with low tidal volume (6 mL/kg), and randomly assigned to receive salbutamol (SALB) or saline 0.9% (CTRL), intravenously (i.v., 10 μg/kg/h) or intratracheally (bolus, 25 μg). Salbutamol doses were targeted at an increase of ≈ 20% in heart rate. Hemodynamics, lung mechanics, and arterial blood gases were measured before and after (at 30 and 60 min) salbutamol administration. At the end of the experiment, lungs were extracted for analysis of lung histology and molecular biology analysis. Values are expressed as mean ± standard deviation, and fold changes relative to NI, CTRL vs. SALB.

Results

The gene expression of ion channels and aquaporin was increased in mild ARDSp, but not ARDSexp. In ARDSp, intravenous salbutamol resulted in higher gene expression of alveolar epithelial sodium channel (0.20 ± 0.07 vs. 0.68 ± 0.24, p < 0.001), aquaporin-1 (0.44 ± 0.09 vs. 0.96 ± 0.12, p < 0.001) aquaporin-3 (0.31 ± 0.12 vs. 0.93 ± 0.20, p < 0.001), and Na-K-ATPase-α (0.39 ± 0.08 vs. 0.92 ± 0.12, p < 0.001), whereas intratracheal salbutamol increased the gene expression of aquaporin-1 (0.46 ± 0.11 vs. 0.92 ± 0.06, p < 0.001) and Na-K-ATPase-α (0.32 ± 0.07 vs. 0.58 ± 0.15, p < 0.001). In ARDSexp, the gene expression of ion channels and aquaporin was not influenced by salbutamol. Morphological and functional variables and edema formation were not affected by salbutamol in any of the ARDS groups, regardless of the route of administration.

Conclusion

Salbutamol administration increased the expression of alveolar epithelial ion channels and aquaporin in mild ARDSp, but not ARDSexp, with no effects on lung morphology and function or edema formation. These results may contribute to explain the negative effects of β2-agonists on clinical outcome in ARDS.     

Entomopathogenic Nematodes Are Not an Alternative to Fenamiphos for Management of Plant-Parasitic Nematodes on Golf Courses in Florida

With the cancellation of fenamiphos in the near future, alternative nematode management tactics for plant-parasitic nematodes (PPN) on golf courses need to be identified. The use of entomopathogenic nematodes (EPN) has been suggested as one possible alternative. This paper presents the results of 10 experiments evaluating the efficacy of EPN at managing PPN on turfgrasses and improving turf performance. These experiments were conducted at various locations throughout Florida over the course of a decade. In different experiments, different EPN species were tested against different species of PPN. Separate experiments evaluated multiple rates and applications of EPN, compared different EPN species, and compared single EPN species against multiple species of PPN. In a few trials, EPN were associated with reductions in certain plant-parasite species, but in other trials were associated with increases. In most trials, EPN had no effect on plant parasites. Because EPN were so inconsistent in their results, we conclude that EPN are not acceptable alternatives to fenamiphos by most turf managers in Florida at this time.     

Comparing ambient, air-convection, and fluid-convection heating techniques in treating hypothermic burn patients, a clinical RCT

Background

Hypothermia in burns is common and increases morbidity and mortality. Several methods are available to reach and maintain normal core body temperature, but have not yet been evaluated in critical care for burned patients. Our unit's ordinary technique for controlling body temperature (Bair Hugger^®+ radiator ceiling + bed warmer + Hotline^®) has many drawbacks e.g.; slow and the working environment is hampered. The aim of this study was to compare our ordinary heating technique with newly-developed methods: the Allon?2001 Thermowrap (a temperature regulating water-mattress), and Warmcloud (a temperature regulating air-mattress).

Methods

Ten consecutive burned patients (> 20% total burned surface area and a core temperature < 36.0°C) were included in this prospective, randomised, comparative study. Patients were randomly exposed to 3 heating methods. Each treatment/measuring-cycle lasted for 6 hours. Each heating method was assessed for 2 hours according to a randomised timetable. Core temperature was measured using an indwelling (bladder) thermistor. Paired t-tests were used to assess the significance of differences between the treatments within the patients. ANOVA was used to assess the differences in temperature from the first to the last measurement among all treatments. Three-way ANOVA with the Tukey HSD post hoc test and a repeated measures ANOVA was used in the same manner, but included information about patients and treatment/measuring-cycles to control for potential confounding. Data are presented as mean (SD) and (range). Probabilities of less than 0.05 were accepted as significant.

Results

The mean increase, 1.4 (SD 0.6°C; range 0.6-2.6°C) in core temperature/treatment/measuring-cycle highly significantly favoured the Allon?2001 Thermowrap in contrast to the conventional method 0.2 (0.6)°C (range -1.2 to 1.5°C) and the Warmcloud 0.3 (0.4)°C (range -0.4 to 0.9°C). The procedures for using the Allon?2001 Thermowrap were experienced to be more comfortable and straightforward than the conventional method or the Warmcloud.

Conclusions

The Allon?2001 Thermowrap was more effective than the Warmcloud or the conventional method in controlling patients' temperatures.     

Effects of GABA on acutely isolated neurons from the gustatory zone of the rat nucleus of the solitary tract

Responses of acutely isolated neurons from the rostral nucleus of the solitary tract (rNST) to GABA receptor agonists and antagonists were investigated using whole-cell recording in current clamp mode. The isolated neurons retain their morphology and can be divided into multipolar, elongate and ovoid cell types. Most rNST neurons (97%), including all three cell types, respond to GABA with membrane hyperpolarization and a reduction in input resistance. The GABA(A) receptor agonist muscimol reduces neuronal input resistance in a concentration-dependent manner, whereas the GABA(B) receptor agonist baclofen had no effect on any of the neurons tested. The GABA and muscimol reversal potentials were both found to be -75 mV Both the GABA competitive antagonist picrotoxin and the GABA(A) receptor antagonist bicuculline block the effect of GABA in a concentration-dependent manner. These results suggest that GABA activates all neurons in the rNST and that inhibitory synaptic activity is important in brainstem processing of gustatory and somatosensory information.      

An evaluation of the Gelman Envirochek® capsule for the simultaneous concentration of Cryptosporidium and Giardia from water

The Gelman Envirochek capsule is a membrane device for the simultaneous concentration of Cryptosporidium oocysts and Giardia cysts from water. Samples are filtered through a Supor^® polyethersulphone membrane with a 1 μm absolute pore size. (Oo)cysts are mechanically eluted from the membrane fibre using a wrist action shaker and a non-ionic detergent and concentrated by centrifugation. The concentrate can be further processed using any separation technique to separate the target organisms from other debris. This method enables multiple samples to be processed within 1 h. Recoveries from seeded tap and source water samples were in excess of 70% for Cryptosporidium and 80% for Giardia.     

Replacement of receptor cells in the hamster vomeronasal epithelium after nerve transection

Chemoreceptor cells in the vomeronasal and olfactory epithelium are replaced following experimentally induced degeneration. This study analyzes quantitatively the time course and degree of vomeronasal receptor cell replacement. Unilateral transection of the vomeronasal nerves in adult hamster was used to induce a retrograde degeneration of receptor cells in the vomeronasal organ. Histological measurement of both number of receptor cells and epithelial thickness were made for recovery times from 0 to 60 days. After nerve transection, there was a gradual degeneration of receptor cells, the number decreasing to 50% of control by day 2 and 16% by day 6. During days 7-15 maximum receptor cell replacement was observed. Cell number increased rapidly and reached a peak on day 15. At recovery times of 40-60 days, cell number returned to the control level. Epithelial thickness, however, decreased to 60-70% during the degeneration period (days 4-6) and did not return to control levels. After 40-60 days epithelial thickness remained at 70% of control. These results demonstrate that vomeronasal receptor cells are replaced following degeneration, but epithelial thickness does not return to control levels. These findings suggest that the number of replacement cells is not limited by the reduced thickness of the epithelium, and that recovery mechanisms may function to restore an optimum number of receptor cells.