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We have previously shown that cardiogenic pulmonary edema fluid (EF) increases [Na.sup.+] and fluid transport by fetal distal lung epithelia (FDLE) (Rafii B, Gillie DJ, Sulowski C, Hannam V, Cheung T, Otulakowski G, Barker PM and O'Brodovich H. J Physiol 544: 537-548, 2002). We now report the effect of EF on [Na.sup.+] and fluid transport by the adult lung. We first studied primary cultures of adult type II (ATII) epithelium and found that overnight exposure to EF increased [N.sup.+]. transport, and this effect was mainly due to factors other than catecholamines. Plasma did not stimulate [N.sup.+]. transport in ATII. Purification of EF demonstrated that at least some agent(s) responsible for the amiloride-insensitive component resided within the globulin fraction. ATII exposed to globulins demonstrated a conversion of amiloride-sensitive short-circuit current ([I.sub.SC]) to amiloride-insensitive L~ with no increase in total [I.sub.SC]. Patch-clamp studies showed that ATII exposed to EF for 18 h had increased the number of highly selective Nan channels in their apical membrane. In situ acute exposure to EF increased the open probability of [N.sup.+].-permeant ion channels in ATII within rat lung slices. EF did increase, by amiloride-sensitive pathways, the alveolar fluid clearance from the lungs of adult rats. We conclude that cardiogenic EF increases [N.sup.+]. transport by adult lung epithelia in primary cell culture, in situ and in vivo. pulmonary edema fluid: alveolar type ii epithelium; sodium channels; lung fluid clearance

Dopamine increases lung fluid clearance. This is partly due to activation of basolateral Na-K-ATPase. However, activation of Na-K-ATPase by itself is unlikely to produce large changes in transepithelial transport. Therefore, we examined apical and basolateral dopamine's effect on apical, highly selective sodium channels [epithelial sodium channels (ENaC)] in monolayers of an alveolar type 2 cell line (L2). Dopamine increased channel open probability ([P.sub.o]) without changing the unitary current. The [D.sub.1] receptor blocker SCH-23390 blocked the dopamine effect, but the [D.sub.2] receptor blocker sulpiride did not. The dopamine-mediated increase in ENaC activity was not a secondary effect of dopamine stimulation of Na-K-ATPase, since ouabain applied to the basolateral surface to block the activity of Na-K-ATPase did not alter dopamine-mediated ENaC activity. Protein kinase A (PKA) was not responsible for dopamine's effect since a PKA inhibitor, H89, did not reduce dopamine's effect. However, cpt-2-O-Me-cAMP, which selectively binds and activates EPAC (exchange protein activated by cAMP) but not PKA, increased ENaC [P.sub.o]. An Src inhibitor, PP2, and the phosphatidylinositol-3-kinase inhibitor, LY-294002, blocked dopamine's effect on ENaC. In addition, an MEK blocker, U0126, an inhibitor of phospholipase [A.sub.2], and a protein phosphatase inhibitor also blocked the effect of dopamine on ENaC Po. Finally, since the cAMP-EPAC-Rap1 pathway also activates DARPP32 (32-kDa dopamine response protein phosphatase), we confirmed that dopamine phosphorylates DARPP32, and okadaic acid, which blocks phosphatases (DARPP32), also blocks dopamine's effect. In summary, dopamine increases ENaC activity by a cAMP-mediated alternative signaling pathway involving EPAC and Rap1, signaling molecules usually associated with growth-factor-activated receptors. single channel recording; ion transport; epithelial sodium channels; L2 lung cells; exchange protein activated by cAMP

Fluid-free alveolar space is critical for normal gas exchange. Influenza virus alters fluid transport across respiratory epithelia producing rhinorrhea, middle ear effusions, and alveolar flooding. However, the mechanism of fluid retention remains unclear. We investigated influenza virus strain A/PR/8/34, which can attach and enter mammalian cells but is incapable of viral replication and productive infection in mammalian epithelia, on epithelial sodium channels (ENaC) in rat alveolar type II (ATII) cells. In parallel, we determined the effects of virus on amiloride-sensitive (i.e., ENaC-mediated) fluid clearance in rat lungs in vivo. Although influenza virus did not change the inulin permeability of ATII monolayers, it rapidly reduced the net volume transport across monolayers. Virus reduced the open probability of single ENaC channels in apical cell-attached patches. U-73122, a phospholipase C (PLC) inhibitor, and PP2, a Src inhibitor, blocked the effect of virus on ENaC. GF-109203X, a protein kinase C (PKC) inhibitor, also blocked the effect, suggesting a PKC-mediated mechanism. In parallel, intratracheal administration of influenza virus produced a rapid inhibition of amiloride-sensitive (i.e., ENaC-dependent) lung fluid transport. Together. these results show that influenza virus rapidly inhibits ENaC in ATII cells via a PLC- and Src-mediated activation of PKC but does not increase epithelial permeability in this same rapid time course. We speculate that this rapid inhibition of ENaC and formation of edema when the virus first attaches to the alveolar epithelium might facilitate subsequent influenza infection and may exacerbate influenza-mediated alveolar flooding that can lead to acute respiratory failure and death. phospholipase C; protein kinase C; epithelial sodium channels; hemagglutinin; acute respiratory distress syndrome; single channels

We investigated the mechanism by which cAMP increases sodium transport in lung epithelial cells. Alveolar type II (ATII) cells have two types of amiloride-sensitive, cation channels: a nonselective cation channel (NSC) and a highly selective channel (HSC). Exposure of ATII cells to cAMP, [beta]-adrenergic agonists, or other agents that increase adenylyl cyclase activity increased activity of both channel types, albeit by different mechanisms. NSC open probability ([P.sub.o]) increased severalfold when exposed to terbutaline, isoproterenol, forskolin, or cAMP analogs without any change in NSC number. In contrast, terbutaline increased HSC number with no significant change in HSC [P.sub.o]. For both channels, the effect of terbutaline was blocked by propranolol and H-89, suggesting a protein kinase A (PKA) requirement for [beta]-adrenergic-induced changes in channel activity. Terbutaline increased cAMP levels in ATII cells, but intracellular calcium also increased. Calcium sequestration with BAPTA blocked [beta]-adrenergic-induced increases in NSC [P.sub.o] but did not alter HSC activity. These observations suggest that [beta]-adrenergic stimulation increases intracellular cAMP and activates PKA. PKA increases HSC number and increases intracellular calcium. The increase in calcium increases NSC [P.sub.o]. Thus increased cAMP levels are likely to increase lung sodium transport regardless of which channel type is present. single channel recording; ion transport; epithelial sodium channels; amiloride; adenosine 3',5'-cyclic monophosphate; [beta]-adrenergic agents; alveolar type II cells

Antisense oligonucleotides were used to manipulate the expression of the respective protein and the patch-clamp technique to study the changes resulting from these manipulations in single-channel characteristics. Findings have indicated that nonselective cation channels belong to the amiloride-sensitive epithelial Na+ (ENaC) family of channels and that the alpha-subunit of ENaC alone or in combination with some protein other than the beta- or gamma-subunit protein is the major component of lung alveolar epithelial cation channels.

The effect of nitric oxide on the activity of apical cation channels in type II alveolar epithelial cells is investigated using patch clamp techniques. This cation channel is permeable to sodium and has a conductance of 20.6 pS. Results of inhibition studies reveal that nitric oxide inhibits this channel. The mechanism of inhibition involves a protein kinase activated by cyclic GMP.

Jain, Lucky, Xi-Juan Chen, Semra Ramosevac, Lou Ann Brown, and Douglas C. Eaton. Expression of highly selective sodium channels in alveolar type II cells is determined by culture conditions. Am J Physiol Lung Cell Mol Physiol 280: L646-L658, 2001.--Alveolar fluid clearance in the developing and mature lungs is believed to be mediated by some form of epithelial Na channels (ENaC). However, single-channel studies using isolated alveolar type II (ATII) cells have failed to demonstrate consistently the presence of highly selective [Na.sup.+] channels that would be expected from ENaC expression. We postulated that in vitro culture conditions might be responsible for alterations in the biophysical properties of [Na.sup.+] conductances observed in cultured ATII cells. When ATII cells were grown on glass plates submerged in media that lacked steroids, the predominant channel was a 21-pS nonselective cation channel (NSC) with a [Na.sup.+]-to-[K.sup.+] selectivity of 1; however, when grown on permeable supports in the presence of steroids and air interface, the predominant channel was a low-conductance (6.6 [+ or -] 3.4 pS, n = 94), highly [Na.sup.+]-selective channel (HSC) with a [P.sub.Na]/[P.sub.K] [is greater than] 80 that is inhibited by submicromolar concentrations of amiloride ([K.sub.0.5] = 37 nM) and is similar in biophysical properties to ENaC channels described in other epithelia. To establish the relationship of this HSC channel to the cloned ENaC, we employed antisense oligonucleotide methods to inhibit the individual subunit proteins of ENaC ([Alpha], [Beta], and [Gamma]) and used patch-clamp techniques to determine the density of this channel in apical membrane patches of ATII cells. Overnight treatment of cells with antisense oligonucleotides to any of the three subunits of ENaC resulted in a significant decrease in the density of HSC channels in the apical membrane cell-attached patches. Taken together, these results show that when grown on permeable supports in the presence of steroids and air interface, the predominant channels expressed in ATII cells have single-channel characteristics resembling channels that are associated with the coexpression of the three cloned ENaC subunits [Alpha]-, [Beta]-, and [Gamma]-ENaC. single-channel recording; air interface; antisense oligonucleotides; epithelial sodium channels

Discusses a study which employed an antisense oligonucleotide methods to block the synthesis of epithelial sodium channel (ENaC) subunit proteins. Characteristics of nonselective cation channels in the apical membrane of alveolar type II (ATII) cells; Functional importance of sodium-permeable nonselective cation channels and their relationship to ENaC; Description of antisense oligonucleotides against ENaC subunits.

We established the optimal model by using the automatic machine learning method to predict the degradation efficiency of herbicide atrazine in soil, which could be used to assess the residual risk of atrazine in soil. We collected 494 pairs of data from 49 published articles, and selected seven factors as input features, including soil pH, organic matter content, saturated hydraulic conductivity, soil moisture, initial concentration of atrazine, incubation time, and inoculation dose. Using the first-order reaction rate constant of atrazine in soil as the output feature, we established six models to predict the degradation efficiency of atrazine in soil, and conducted comprehensive analysis of model performance through linear regression and related evaluation indicators. The results showed that the XGBoost model had the best performance in predicting the first-order reaction rate constant ( k ). Based on the prediction model, the feature importance ranking of each factor was in an order of soil moisture > incubation time > pH > organic matter > initial concentration of atrazine > saturated hydraulic conductivity > inoculation dose. We used SHAP to explain the potential relationship between each feature and the degradation ability of atrazine in soil, as well as the relative contribution of each feature. Results of SHAP showed that time had a negative contribution and saturated hydraulic conductivity had a positive contribution. High values of soil moisture, initial concentration of atrazine, pH, inoculation dose and organic matter content were generally distributed on both sides of SHAP=0, indicating their complex contributions to the degradation of atrazine in soil. The XGBoost model method combined with the SHAP method had high accuracy in predicting the performance and interpretability of the k model. By using machine learning method to fully explore the value of historical experimental data and predict the degradation efficiency of atrazine using environmental parameters, it is of great significance to set the threshold for atrazine application, reduce the residual and diffusion risks of atrazine in soil, and ensure the safety of soil environment.

Objective: To understand the immune molecular landscapes of the two major costimulatory and coinhibitory pathways (B7 and TNFR families) in oral squamous cell carcinoma., Methods: The B7 family members (CD80, CD86, CD274, ICOSLG, CD276, VTCN1, NCR3LG1, HHLA2 and PDCD1LG2) and TNFR family members (TNFSF4, CD40, CD70, TNFSF9, TNFRSF14 and TNFSF18) were used to analyse the costimulatory and coinhibitory pathway alterations in oral squamous cell carcinoma. The online tools UCSC Xena and cBioPortal were used to derive oral squamous cell carcinoma patients' clinical parameters, mRNA levels, mutations, DNA copy number alterations and methylation levels. The correlations between mRNA levels and methylation levels were determined using Spearman's correlation analysis. A Kaplan-Meier survival analysis was performed to examine the relationships between mRNA expression levels and overall survival., Results: Compared with normal oral epithelial tissues, approximately 23.1% of patients showed upregulation of B7 expression and 15.3% showed upregulation of TNFR expression in oral squamous cell carcinoma, with CD274 (PD-L1) upregulation being the most common alteration. Mutations and copy number alterations were shown to have little effect on B7 and TNFR expression. The mRNA levels of B7 and TNFR genes were negatively correlated with their methylation levels. Furthermore, oral squamous cell carcinoma patients with high expression levels of CD274 showed poor overall survival, while those with high expression levels of CD276 or HHLA2 showed good clinical outcomes., Conclusion: This study elucidated the molecular landscapes of the B7 and TNFR genes in oral squamous cell carcinoma, which could provide a novel strategy for clinical therapy.

The application of sewage and manure in protected vegetable cultivation can induce the occurrence of heavy metals contamination. The present research studied the transformation of heavy metals (Cd, Cu, Pb and Zn) by incubating contaminated protected soil with maize straw and then leaching. The results showed that soil pH was significantly decreased, being more evident in maize straw treatment; soil Eh dropped quickly below -280 mV. Maize straw treatment promoted the activation of Cd, Cu, Pb and Zn from soil, and the total percent of oxidizable fraction and residual fraction of Cd, Cu, Pb and Zn declined at 9 th day; the amount of Cd, Cu, Pb and Zn in soil reduced 18.1%, 19.0%, 16.1% and 15.7% at 15 th day, respectively. Compared to control, maize straw treatment could increase the concentrations of dissolved Cd and Zn, but Cu decreased. The concentration of colloidal-bound Cd and Pb increased, Cu decreased and no significant change occurred in Zn in maize straw treatment. Strong reductive approach could activate heavy metals in protected vegetable soil, increase the risk of heavy metals accumulation in vegetables, and possibly cause water pollution accompanied with soil water mobilization.