Equal Volume Of Air Research Articles

Involvement of p38 mitogen-activated protein kinase in altered expressions of AQP1 and AQP4 after carbon monoxide poisoning in rat astrocytes.

Cerebral oedema is a major pathological change of acute carbon monoxide (CO) poisoning, the pathogenesis of which is still unclear. In the aquaporin (AQP) water channel family, AQP1 and AQP4 play critical roles in the progress of cerebral oedema of various neuropathological events. However, their functions in CO poisoning have not been demonstrated. In this study, we investigated the expressions of AQPs and associated mechanisms of brain injury in an acute CO poisoning rat model. Compared with the control injected intraperitoneally with equal volume of air, the dry weight/wet weight (DW/WW) ratio of brain water content, levels of AQP1, AQP4, phosph-p38 mitogen-activated protein kinase (p-p38 MAPK) and astrocyte marker, glial fibrillary acidic protein (GFAP) in the frontal cortex and hippocampal CA1 of acute CO poisoning group significantly increased at 6, 12, 24hours after CO injection. Intracerebroventricular injection with a p38 MAPK inhibitor, SB203580 (200µmol/L/kg/d), before CO injection reduced water content in the brain tissues and significantly decreased levels of AQP1, AQP4, p-p38 MAPK and GFAP. Therefore, our study showed that the overexpressions of AQP1 and AQP4 were involved in the development of CO poisoning-induced cerebral oedema, which could be attenuated by inhibition of p-p38 MAPK signalling. Manipulation of AQPs and p38 MAPK may be a new therapeutic strategy for acute CO poisoning.

Reflex bronchoconstriction evoked by inhaled nicotine aerosol in guinea pigs: role of the nicotinic acetylcholine receptor.

Inhaled cigarette smoke stimulated vagal bronchopulmonary C fibers via an action of nicotine on neuronal nicotinic acetylcholine receptor (nAChR). Recent studies have reported that nicotine at high concentrations can also activate the transient receptor potential ankyrin 1 receptor (TRPA1) expressed in these sensory nerves. This study was performed to characterize the airway response to inhaled nicotine aerosol and to investigate the relative roles of nAChR and TRPA1 in this response. Guinea pigs were anesthetized and mechanically ventilated; one tidal volume of nicotine aerosol (2% solution) was diluted by an equal volume of air and delivered directly into the lung via a tracheal cannula in a single breath. Our results showed the following: 1) Inhalation of nicotine aerosol triggered an immediate and pronounced bronchoconstriction; the increase in total pulmonary resistance reached a peak of 588 ± 205% (mean ± SE) in 10-40 s, which gradually returned to baseline after 1-5 min. 2) Pretreatment with either atropine (iv) or mecamylamine (aerosol) almost completely abolished the nicotine-induced bronchoconstriction; the mecamylamine pretreatment did not block the bronchoconstriction and bradycardia evoked by electrical stimulation of the distal end of one sectioned vagus nerve, indicating its minimal systemic effects. 3) Pretreatment with HC-030031, a selective TRPA1 antagonist, abolished the bronchoconstriction induced by allyl isothiocyanate, a selective TRPA1 agonist, but did not attenuate the nicotine-evoked bronchoconstriction. In conclusion, inhalation of a single breath of nicotine aerosol evoked acute bronchoconstriction mediated through the cholinergic reflex pathway. This reflex response was triggered by activation of nAChR, but not TRPA1, located in airway sensory nerves. NEW & NOTEWORTHY Recent reports revealed that nicotine at high concentration activated transient receptor potential ankyrin 1 receptor (TRPA1) expressed in vagal bronchopulmonary sensory nerves. This study showed that inhalation of a single breath of nicotine aerosol consistently evoked acute bronchoconstriction that was mediated through the cholinergic reflex pathway and triggered by activation of nicotinic acetylcholine receptor, but not TRPA1, located in these nerves. This is new and important information considering the recent rapid and alarming rise in the prevalence of e-cigarette use for nicotine inhalation.

EXPERIMENTAL RESEARCH INTO THE TWO-LEVEL CYLINDRICAL CYCLONE WITH A DIFFERENT NUMBER OF CHANNELS / DVIEJŲ LYGIŲ CILINDRINIO CIKLONO SU SKIRTINGU KANALŲ SKAIČIUMI EKSPERIMENTINIAI TYRIMAI

The multichannel two-level cyclone has been designed for separating solid particles from airflow and built at the Laboratory of Environmental Protection Technologies of Vilnius Gediminas Technical University. The conducted research is aimed at determining air flow distribution at two levels and channels of the multichannel cyclone. The multifunctional meter Testo-400 and the dynamic Pitot tube have been used form easuring air flow rates in the channels. The obtained results show that the equal volume of air gets into two levels installed inside the cyclone, and rates are distributed equally in the channels of these levels. The maximum air flow rate is recorded in the first channel and occurs when half-rings are set in such positions so that 75% of air flow returns to the previous channel. The biggest aerodynamic resistance is 1660 Pa and has been recorded in the cyclone having eight channels under air flow distribution ratio 75/25. The highest air purification efficiency has been observed in the two-level six-channel cyclone under air flow distribution ratio 75/25. The effectiveness of separating granite particles is 92.1% and that of wood particles – 91.1 when the particles are up to 20 μm in diameter. Dviejų lygių daugiakanalis ciklonas skirtas kietosioms dalelėms iš oro srauto atskirti. Toks ciklonas sukurtas Vilniaus Gedimino technikos universiteto Aplinkos apsaugos laboratorijoje. Tyrimais siekiama nustatyti oro srauto pasiskirstymą daugiakanalio ciklono lygiuose ir kanaluose. Oro greičiams kanaluose nustatyti naudojamas daugiafunkcis matuoklis „Testo-400“ ir dinaminis Pito vamzdelis. Gauti rezultatai parodė, kad į ciklone įrengtus lygius patenka vienodas oro tūris, ir greičiai šių lygių kanaluose pasiskirsto vienodai. Didžiausias greitis užfiksuotas pirmajame kanale. Didžiausias yra tuo atveju, kai pusžiedžiai sudėti taip, jog 75 % oro srauto grįžtų į ankstesnį kanalą, o mažiausias tada, kai į ankstesnį kanalą grįžta 25 % oro srauto. Didžiausias išmatuotas aerodinaminis pasipriešinimas yra esant aštuoniems kanalams bei 75/25 oro srautų pasiskirstymo santykiui ir siekia 1660 Pa. Ištyrus ciklono su skirtingu kanalų skaičiumi efektyvumą nustatyta, kad geriausiai daleles iš oro atskiria šešiakanalis ciklonas, kuriame oro srautų pasiskirstymo santykis yra 75/25. Granito dalelių iki 20 μm atskyrimo 92,1 %, o medienos dalelių – 91,1 %.

Histological examination of PLGA nanospheres for intratracheal drug administration

Polylactide–glycolide (PLGA) nanospheres were reported as useful pulmonary drug delivery carriers for improving the pharmacological effect of drug. This paper describes the pathological and histological examinations of tissues after intratracheal instillation of drug encapsulated PLGA nanospheres. After intratracheally introducing FITC encapsulated PLGA nanospheres (dispersed in the 0.5 ml saline followed by mixing with an equal volume of air) to a rat, FITC was found existing in the rat's lungs, liver, kidney, brain, spleen and pancreas as demonstrated by immuno-histo-chemical staining with the dye. In this study, FITC stayed in alveoli at least for 1.5 h after the intratracheal administration of the PLGA nanospheres, but the FITC almost disappeared 24 h later. In addition, it was found that the PLGA nanospheres were absorbed in the blood immediately (within 0.25 h after the intratracheal administration) through the type 1 alveolar epithelium cell. Furthermore, the PLGA nanospheres were found resistant to uptake by macrophages such as alveolus macrophages and kupffer cells. The results showed that the possibility to induce tissue damage caused by the excessive immune response from the deposition of PLGA nanospheres was very low, because the nanospheres were not treated as foreign substances.

Surfactant (beractant) therapy for infants with congenital diaphragmatic hernia on ECMO: Evidence of persistent surfactant deficiency

Infants with congenital diaphragmatic hernia (CDH) on extracorporeal membrane oxygenation (ECMO) can have initial lung atelectasis which, in survivors, gradually improves over time. To test the hypothesis that these patients could benefit from surfactant therapy, infants with CDH (born at >34 weeks' gestation) on ECMO received either four doses of modified bovine lung surfactant extract (beractant) (surfactant group, n = 9) or an equal volume of air (control group, n = 8). Tracheal aspirate surfactant protein-A (SP-A) concentrations were initially low, and then increased over time in both CDH groups ( P = .0021); however, levels remained low when compared with those of infants on ECMO who had other diagnoses ( P = .04). Lung compliance (C L), time to extubation, time on oxygen, and total no. of hospital days were not different between the two groups. Infants with CDH had persistently elevated right ventricular pressure (RVP) at cessation of bypass when compared with non-CDH infants on ECMO (RVP = 53.25 mm Hg ± 19.52 in the CDH group, 32.90 ± 10.63 in the non-CDH group; P = .0121). The findings suggest that the postnatal surfactant deficiency may be more persistent in CDH infants than in non-CDH infants on ECMO. However, CDH remains a multifactorial condition, with delayed improvement, because of persistence of pulmonary hypertension, difficulties with vascular remodeling, degree of lung hypoplasia, or compromised respiratory mechanics.

Improved pulmonary outcome after exogenous surfactant therapy for respiratory failure in term infants requiring extracorporeal membrane oxygenation

A blinded, randomized, controlled study was designed to test whether multiple-dose surfactant therapy would improve pulmonary outcome in term infants with respiratory failure, resulting in a shortened period of extracorporeal membrane oxygenation (ECMO). Infants > or = 34 weeks of gestational age in severe respiratory failure and receiving ECMO were stratified by diagnosis and then randomly assigned to the treatment or the control group. Four doses of modified bovine lung surfactant extract (beractant) were administered to the surfactant group (n = 28), and an equal volume of air was administered to the control group (n = 28). Lung compliance was initially low in both groups; after treatment, values were higher with time in the surfactant group (F = 5.40, p = 0.026). The ECMO treatment period was significantly shorter in the surfactant group (mean +/- SD: 107 +/- 33 hours vs 139 +/- 54 hours for the control group; U = 232, p = 0.023). Tracheal aspirate concentrations of surfactant protein A were low in both groups, and then increased steadily to a higher level in the surfactant group (F = 2.58, p = 0.04). The overall incidence of complications after ECMO was decreased in the surfactant group (18% vs 46% for the control group; chi-square value = 5.004, p = 0.025). Radiographic scores, echocardiographic findings, incidence of intracranial or pulmonary hemorrhage and bronchopulmonary dysplasia, time to extubation, duration of oxygen therapy, and duration of hospitalization did not differ between the two groups. Beractant in this population improved pulmonary mechanics, increased surfactant protein A content in tracheal aspirate, decreased time on ECMO duration, and reduced disease complications.

The respiratory gas exchange of sea turtle nests (Chelonia, Caretta)

Sea turtles lay about 100 leathery-shelled eggs in a 25 cm diameter chamber carefully excavated about 50 cm deep in a nesting beach, where the eggs exchange gases (at approximately 28 C) during their 60-day incubation period. The sand surrounding the spherical nest chamber restricts the diffusion of gases into and out of the nest so that as embryonic development progresses, P O 2 decreases and P CO 2 increases in the gas inside the nest. P O 2 falls to 80–100 torr and P CO 2 rises to 40–60 torr inside 100-egg manmade Chelonia and Caretta nests. The change in gas tensions in the nest during development is very similar to that seen in the air cell of the chicken egg. Gas tensions inside the turtle nest and in the sand surrounding the nest can be described by a radial steady-state diffusion model. The rate of diffusion of gases in the sand is 30–50% of the rate found in the nest and 6–12% of the rate found in an equal volume of air. The sand surrounding the turtle nest appears to determine the gas exchange of the eggs in the nest and is functionally analogous to the shell surrounding the chicken embryo. The female sea turtle may construct her nest so as to maximize its gas exchange and minimize gas partial pressure gradients inside the nest.

The effects of inhaling a 35 per cent CO 2-65 per cent O 2 mixture upon anxiety level in neurotic patients

Wolpe has reported the use of a 35 per cent CO 2-65 per cent O 2 mixture to relax patients who cannot otherwise be relaxed sufficiently to allow desensitization. In this investigation, the anxiety-reducing effects of single inhalations of a 35 per cent CO 2-65 per cent O 2 were studied on twelve patients, all of whom had been diagnosed by their doctors as having a high level of anxiety. On the basis of the subjects' ratings, this mixture was more effective than was an equal volume of air which was breathed through the same apparatus as was the experimental mixture. Evidence is offered which suggests that the decrement in anxiety which followed administration of the 35 per cent CO 2-65 per cent O 2 mixture was due to some effect of the gas other than the hyperventilation which it induces.

The effects of inhaling a 35 per cent CO 2-65 per cent O 2 mixture upon anxiety level in neurotic patients

Wolpe has reported the use of a 35 per cent CO 2-65 per cent O 2 mixture to relax patients who cannot otherwise be relaxed sufficiently to allow desensitization. In this investigation, the anxiety-reducing effects of single inhalations of a 35 per cent CO 2-65 per cent O 2 were studied on twelve patients, all of whom had been diagnosed by their doctors as having a high level of anxiety. On the basis of the subjects' ratings, this mixture was more effective than was an equal volume of air which was breathed through the same apparatus as was the experimental mixture. Evidence is offered which suggests that the decrement in anxiety which followed administration of the 35 per cent CO 2-65 per cent O 2 mixture was due to some effect of the gas other than the hyperventilation which it induces.

Encephalography by the displacement technique.

The commonly accepted technique of performing encephalography has been to replace a volume of spinal fluid with an equal volume of air or other gases. Adaptations of this technique have been made by Gardner and Nichols,1by Davidoff and Dyke,2and by Lindgren,3who used smaller quantities of gas and/or first injected air before withdrawing any spinal fluid. In 1955 Slosberg et al.4introduced a new technique of encephalography, which was called the minimal withdrawal technique. This consisted of injecting 10 to 80 cc. of air into the lumbar subarachnoid space while withdrawing no more than 5 cc. of spinal fluid. A group of 35 patients was studied. Three of these had early papilledema, and four had spinal fluid pressures above 200 mm. H2O.5An average of 44 cc. of air was injected. Five patients had no headache during the procedure, but these

A description of a hydropneumatic baroscope

The liability of the ordinary mercurial barometer to derangement and to fracture, led the author to the construction of an instrument for measuring atmospheric pressure that should be exempt from these objections. It consists of a float, formed by a brass tube, having the shape of the frustum of an inverted cone, nine inches long, two inches in diameter above, and one inch below, and its content being about fourteen cubic inches. From the centre of the upper and wider end, which is closed, a brass wire proceeds, surmounted by a cup, for the purpose of holding such weights as are necessary for bringing the float, when immersed in water, to the same constant level. The lower and smaller end of the tube is closed by a brass plug, sufficiently heavy to sink the instrument to the proper depth, and maintain its position, and having a small perforation in its centre. This float is inclosed in a case, containing the water in which it is to be immersed, and which is to be raised to a constant given temperature by a spirit lamp burning beneath it. The float being first filled with water, a given portion of this water is poured out into a measure of known capacity, and is consequently replaced by an equal volume of air, the dilatations or contractions of which will, when the temperature is constant, be dependent only on the external pressure of the atmosphere; and the latter will, therefore, be indicated by the weights requisite to be placed in the cup of the float, in order to maintain it at the same level in the fluid, on the principle of the hydrometer. The author gives a minute description of all the parts of the apparatus, of the method of using it, and of the adjustments and calculations required for determining by its means the difference of level of two stations.