Regulation of the sodium potassium adenosine triphosphatase (Na,K-ATPPase) by FXYD 2

The Na,K-ATPase, or Na+ pump is an integral membrane protein found in the cells of virtually all higher eukaryotes and is one of the most important systems in cellular energy transduction. Na,K-ATPase catalyzes the electrogenic exchange of three intracellular Na+ for two extracellular K+ ions coupled to the hydrolysis of one molecule of ATP. The research described in this thesis concerns the regulation of the Na,K-ATPase by FXYD 2, a member of the FXYD family of small single transmembrane proteins. FXYD 2, commonly known as the gamma modulator, is located primarily in the kidney and has a role in modulating the enzyme's apparent affinities for ligands. This study has addressed several aspects of gamma structure and function, namely its function in intact cells, the function of the gamma transmembrane domain, and delineation of regions of the enzyme's catalytic alpha subunit with which gamma interacts. Transport assays using intact transfected HeLa cells showed that the two gamma variants, gammaa and gammab, cause (i) an increase in K+/Na+ antagonism, seen as an increase in K'Na at high K+ concentration, and (ii) an increase in apparent ATP affinity seen as an increase in ouabain-sensitive K+ influx as a function of ATP concentration. These results are consistent with those obtained earlier with unsided membrane preparations. The present study also showed a gamma-mediated increase in steady-state intracellular Na+ concentration and, in contrast to assays using permeabilized membranes, a gamma-mediated increase in apparent affinity for extracellular K+. Experiments with synthetic gamma transmembrane (gamma-TM) peptides provided insight into the role of the TM region such that incubation of these peptides with membranes containing alphabeta pumps modulated K'Na similarly to transfected full-length gamma, indicating that the TM domain alone can cause an increase in K'Na at high K+ concentration. Results with gamma-TM bearing the Gly41→Arg missense mutation associated with familial renal hypomagnesemia provided direct evidence that this mutation prevents gamma association with alphabeta pumps. In a study aimed to identify regions of alpha critical for the functional effects of gamma, interactions of alpha1/alpha2 (and the reverse alpha2/alpha1) chimeras with gamma showed the importance of the carboxy terminus, particularly TM 9. The chimera data also indicate that interactions of transmembrane regions of the catalytic alpha subunit with FXYD proteins are not necessarily the sole determinants of the kinetic effects of gamma on Na+ affinity since the extramembranous L7/8 loop of a appears to modulate intramembranous alpha-gamma interactions that mediated the increase in K+/Na+ antagonism

Enhanced performance of optimised partially textured load bearing surfaces

Textured surfaces have been shown to provide enhanced tribological performance in a variety of contacts. Numerical analysis and optimisation methods are combined for application-oriented texture optimisation. However, an analytical approach is advantageous in providing more generic in-depth understanding of the nature of the relationships between texture parameters and objective functions, such as enhanced load carrying capacity and reduced friction. The paper outlines such an approach to obtain a set of global optimum design parameters for partially textured surfaces. The optimised results are expressed in dimensionless form, which enables their use for a variety of applications. The performance of optimised partially textured sliding surfaces is compared with the other conventional bearing geometries in their optimum state

Protein Phosphatase 2A Interacts with the Na+,K+-ATPase and Modulates Its Trafficking by Inhibition of Its Association with Arrestin

Background: The P-type ATPase family constitutes a collection of ion pumps that form phosphorylated intermediates during ion transport. One of the best known members of this family is the Na +,K +-ATPase. The catalytic subunit of the Na +,K +-ATPase includes several functional domains that determine its enzymatic and trafficking properties. Methodology/Principal Findings: Using the yeast two-hybrid system we found that protein phosphatase 2A (PP2A) catalytic C-subunit is a specific Na +,K +-ATPase interacting protein. PP-2A C-subunit interacted with the Na +,K +-ATPase, but not with the homologous sequences of the H +,K +-ATPase. We confirmed that the Na +,K +-ATPase interacts with a complex of A- and C-subunits in native rat kidney. Arrestins and G-protein coupled receptor kinases (GRKs) are important regulators of G-protein coupled receptor (GPCR) signaling, and they also regulate Na +,K +-ATPase trafficking through direct association. PP2A inhibits association between the Na +,K +-ATPase and arrestin, and diminishes the effect of arrestin on Na +,K +-ATPase trafficking. GRK phosphorylates the Na +,K +-ATPase and PP2A can at least partially reverse this phosphorylation. Conclusions/Significance: Taken together, these data demonstrate that the sodium pump belongs to a growing list of io

Elective cancer surgery in COVID-19-free surgical pathways during the SARS-CoV-2 pandemic: An international, multicenter, comparative cohort study

PURPOSE As cancer surgery restarts after the first COVID-19 wave, health care providers urgently require data to determine where elective surgery is best performed. This study aimed to determine whether COVID-19–free surgical pathways were associated with lower postoperative pulmonary complication rates compared with hospitals with no defined pathway. PATIENTS AND METHODS This international, multicenter cohort study included patients who underwent elective surgery for 10 solid cancer types without preoperative suspicion of SARS-CoV-2. Participating hospitals included patients from local emergence of SARS-CoV-2 until April 19, 2020. At the time of surgery, hospitals were defined as having a COVID-19–free surgical pathway (complete segregation of the operating theater, critical care, and inpatient ward areas) or no defined pathway (incomplete or no segregation, areas shared with patients with COVID-19). The primary outcome was 30-day postoperative pulmonary complications (pneumonia, acute respiratory distress syndrome, unexpected ventilation). RESULTS Of 9,171 patients from 447 hospitals in 55 countries, 2,481 were operated on in COVID-19–free surgical pathways. Patients who underwent surgery within COVID-19–free surgical pathways were younger with fewer comorbidities than those in hospitals with no defined pathway but with similar proportions of major surgery. After adjustment, pulmonary complication rates were lower with COVID-19–free surgical pathways (2.2% v 4.9%; adjusted odds ratio [aOR], 0.62; 95% CI, 0.44 to 0.86). This was consistent in sensitivity analyses for low-risk patients (American Society of Anesthesiologists grade 1/2), propensity score–matched models, and patients with negative SARS-CoV-2 preoperative tests. The postoperative SARS-CoV-2 infection rate was also lower in COVID-19–free surgical pathways (2.1% v 3.6%; aOR, 0.53; 95% CI, 0.36 to 0.76). CONCLUSION Within available resources, dedicated COVID-19–free surgical pathways should be established to provide safe elective cancer surgery during current and before future SARS-CoV-2 outbreaks

Elective Cancer Surgery in COVID-19-Free Surgical Pathways During the SARS-CoV-2 Pandemic: An International, Multicenter, Comparative Cohort Study.

PURPOSE: As cancer surgery restarts after the first COVID-19 wave, health care providers urgently require data to determine where elective surgery is best performed. This study aimed to determine whether COVID-19-free surgical pathways were associated with lower postoperative pulmonary complication rates compared with hospitals with no defined pathway. PATIENTS AND METHODS: This international, multicenter cohort study included patients who underwent elective surgery for 10 solid cancer types without preoperative suspicion of SARS-CoV-2. Participating hospitals included patients from local emergence of SARS-CoV-2 until April 19, 2020. At the time of surgery, hospitals were defined as having a COVID-19-free surgical pathway (complete segregation of the operating theater, critical care, and inpatient ward areas) or no defined pathway (incomplete or no segregation, areas shared with patients with COVID-19). The primary outcome was 30-day postoperative pulmonary complications (pneumonia, acute respiratory distress syndrome, unexpected ventilation). RESULTS: Of 9,171 patients from 447 hospitals in 55 countries, 2,481 were operated on in COVID-19-free surgical pathways. Patients who underwent surgery within COVID-19-free surgical pathways were younger with fewer comorbidities than those in hospitals with no defined pathway but with similar proportions of major surgery. After adjustment, pulmonary complication rates were lower with COVID-19-free surgical pathways (2.2% v 4.9%; adjusted odds ratio [aOR], 0.62; 95% CI, 0.44 to 0.86). This was consistent in sensitivity analyses for low-risk patients (American Society of Anesthesiologists grade 1/2), propensity score-matched models, and patients with negative SARS-CoV-2 preoperative tests. The postoperative SARS-CoV-2 infection rate was also lower in COVID-19-free surgical pathways (2.1% v 3.6%; aOR, 0.53; 95% CI, 0.36 to 0.76). CONCLUSION: Within available resources, dedicated COVID-19-free surgical pathways should be established to provide safe elective cancer surgery during current and before future SARS-CoV-2 outbreaks

Effects of UV-B radiation και ozone on morphological, anatomical, physiological and qualitative characteristics of cotton (Gossypium hirsutum L.)

Effects of UV-B radiation on cotton plants The intensity of UV-B radiation ( wave length 280-320nm), that reaches the ground surface, is predicted that will increase in the near future. A study was conducted for the effects of three levels of UV-B radiation was examined on certain morphological, anatomical, physiological και qualitative characteristics of cotton (Gossypium hirsutum L.) cultivars Romanos και Allegria. From the emergence to uprooting, the plants of cotton were grown in closed growth chambers και were exposed to the following levels of UV-B radiation a) 0w/m2 for control plants. b) 0,1365w/m2. It is the medium value of UV-BBE radiation for the city of Volos, with geographic longitude 220 57’ και north latitude 390 22’ , at the month of July. c) 0,2232w/m2. It is the medium value of UV-BBE radiation, when the density of statospheric ozone will be decreased 30% in future, for the city of Volos, at the month of July. The plants were exposed to the above levels of UV-B radiation for eight hours during a day και night, from 8:00 to 16:00 h, while at the same time were illuminated artificially with photosynthetic active radiation. The increase of UV-B radiation levels induced to the plants the following: a) It increased the number of stomata, the epicuticular wax content of leaves, the thickness of all histological components of fully expanded leaves (superior cuticle, superior epidermis, palisade parenchyma, spongy parenchyma, inferior epidermis και inferior cuticle), the total thickness of leaves, the palisade layers of leaves, the short fiber index και the reflectance of cotton fibers.b)It increased or decreased the number of epidermal cells και the stomatal conductance. c) It did not have a significant effect on the stomatal length, on the number of non glandular hairs και on the maximum staminal column length. d) It decreased the stomatal width, the chlorophyll content, the net photosynthetic rate, the plant height, the internode length of the main stem, the bract length και area, the petal length και area, the anther number, the pollen grain germination, the leaf area, the dry leaf weight, the boll number, the total length of branches, the dry weight of main stem-branches- bracts- carpophylls, the dry root weight, the quantitative characteristics of cotton (raw cotton weight, seed weight, lint weight, yield και the ratio of lint weight to seed weight), the fiber strength, the maturity index και the spinning consistancy index. e) Visible necrotic symptoms were not observed, during the effects of UV-B radiation on cotton pants. Effects of tropospheric ozone on cotton plants The cultivars Romanos και Allegria of cotton (Gossypium hirsutum L.), were exposed to two levels of ozone, CF (on control plants) και 100ppb for investigating the effects of ozone concentration of 100ppb, on certain morphological, anatomical, physiological και qualitative characteristics of cotton. Plant exposure to previous levels of ozone, began eight days after emergence of plants και interrupted one day before removing of leaves, for calculating leaf area. The plants were exposed to two levels of ozone, in closed fumigated chambers, for seven continuous hours per day during of their illumination with artificial visible light. The concentration of 100ppb of ozone, induced to the plants in relation to the control plants, the following: a) It increased the number of stomata, the number of epidermal cells και the yellowness of cotton fibers.b) It did not have a significant effect to the stomatal length και width, to the number of non glandular hairs of leaf areas between the main veins και to the epicuticular wax content. c) It reduced the number of non glandular hairs of main veins of leaf surface, the plant height, the chlorophyll content, the net photosynthetic rate, the stomatal conductance, the bract length και area, the internode length of main stem, the petal length και area, the maximum length of staminal tube, the anther number, the pollen grain germination, the leaf area, the leaf dry weight, the boll number, the total weight of raw cotton, the total length of branches, the dry weight of main stem-branches- bracts-carpophylls, the root dry weight, the thickness of histological components of fully expanded leaves (superior cuticle, superior epidermis, palisade parenchyma, spongy parenchyma, inferior epidermis και inferior cuticle), the total leaf thickness, the quantitative characteristics of cotton (raw cotton weight, seed weight, lint weight, yield και the ratio of lint weight to seed weight) the fiber strength. d) Visible symptoms from the effects of ozone on plants, were white necrotic patches on interveinal areas of leaves.1.1. Επίδραση της uv-b ακτινοβολίας στα φυτά του βαμβακιού. Η ένταση της υπεριώδους ακτινοβολίας -Β (μήκους κύματος 280-320nm) που φθάνει στην επιφάνεια της γης προβλέπεται ότι θα αυξηθεί στο εγγύς μέλλον. Για αυτόν τον λόγο μελετήθηκε η επίδραση τριών επιπέδων UV-B ακτινοβολίας σε ορισμένα μορφολογικά ανατομικά φυσιολογικά και ποιοτικά γνωρίσματα των ποικιλιών του βαμβακιού (Gossypium hirsutum L.) Romanos και Allegria. Από τη βλάστηση μέχρι την εκρίζωσή τους (στάδιο συγκομιδής) τα φυτά του βαμβακιού βρίσκονταν μέσα σε κλειστούς θαλάμους και εκτίθονταν σε τρία επίπεδα της UV-B ακτινοβολίας α) 0w/m2, στα φυτά μάρτυρες, β) 0,1365w/m2, η οποία είναι η μέση τιμή της UV-BΒΕ ακτινοβολίας για την πόλη του Βόλου με γεωγραφικό μήκος 22ο 57’ και βόρειο, γεωγραφικό πλάτος 39ο 22’ κατά το μήνα Ιούλιο και γ) 0,2232 w/m2 που προβλέπεται ότι θα είναι η μέση τιμή της UV-BΒΕ ακτινοβολίας για την πόλη του Βόλου κατά τον μήνα Ιούλιο όταν στο μέλλον θα μειωθεί κατά 30% η πυκνότητα του στρατοσφαιρικού όζοντος. Τα φυτά εκτίθονταν στα παραπάνω επίπεδα της UV-B ακτινοβολίας για οκτώ ώρες το 24ωρο από τις 8:00 έως τις 16:00 ενώ παράλληλα φωτίζονταν τεχνητά με φωτοσυνθετικά ενεργή ακτινοβολία. Η αύξηση των επιπέδων της UV-B ακτινοβολίας προκάλεσε στα φυτά τα παρακάτω: α) Ορατά νεκρωτικά συμπτώματα δεν παρατηρήθηκαν κατά την επίδραση της UV-B ακτινοβολίας στα φυτά του βαμβακιού. β)Αύξησε τον αριθμό των στομάτων, το περιεχόμενο σε κηρούς της εφυμενίδας των φύλλων, το πάχος όλων των ιστολογικών στοιχείων των πλήρως αναπτυγμένων φύλλων (ανώτερης εφυμενίδας, ανώτερης επιδερμίδας, δρυφακτοειδούς παρεγχύματος, σπογγώδους παρεγχύματος, κατώτερης επιδερμίδας και κατώτερης εφυμενίδας), το συνολικό πάχος των φύλλων, τις σειρές των δρυφακτοειδών κυττάρων των φύλλων, το ποσοστό των κοντών ινών και τη λευκότητα των ινών του βαμβακιού. γ) Αύξησε συνήθως τον αριθμό των επιδερμικών κυττάρων και τη στοματική αγωγιμότητα. δ) Δεν είχε σημαντική επίδραση στο μήκος των καταφρακτικών κυττάρων των στομάτων, στον αριθμό των μη αδενωδών τριχών και στο μήκος της σωληνοειδούς κατασκευής των στημόνων. ε) Μείωσε το πλάτος των καταφρακτικών κυττάρων των στομάτων, το περιεχόμενο σε χλωροφύλλη, τον καθαρό ρυθμό φωτοσύνθεσης, το ύψος των φυτών, το μήκος των μεσογονάτιων διαστημάτων του κυρίως βλαστού, το μήκος και το εμβαδό των βρακτείων, το μήκος και το εμβαδό των πετάλων, τον αριθμό των ανθήρων, τη βλαστικότητα των γυρεοκόκκων, το εμβαδό των φύλλων, το ξηρό βάρος των φύλλων, τον αριθμό των καρυδιών, το συνολικό μήκος των κλάδων, το ξηρό βάρος του κυρίως βλαστού - κλάδων - βρακτείων - καρποφύλλων, το ξηρό βάρος των ριζών, τα ποσοτικά χαρακτηριστικά του βαμβακιού (βάρος του σύσπορου, βάρος των σπερμάτων, βάρος των ινών, απόδοση και τον λόγο του βάρους των ινών προς το βάρος των σπερμάτων), την αντοχή των ινών, το ποσοστό των ώριμων ινών και τον δείκτη σταθερότητας της κλωσιμότητας. 1.2. Επίδραση του τροποσφαιρικού όζοντος στα φυτά του βαμβακιού Οι ποικιλίες του βαμβακιού (Gossypium, hirsutum L.) Romanos & Allegria εκτέθηκαν σε δύο επίπεδα όζοντος CF (στα φυτά μάρτυρες) και 100ppb, για να μελετηθεί η επίδραση της συγκέντρωσης του όζοντος, σε ορισμένα μορφολογικά, ανατομικά, φυσιολογικά και ποιοτικά γνωρίσματα του βαμβακιού. Το παραπάνω σύμβολο CF σημαίνει αέρας φιλτραρισμένος από ενεργό άνθρακα, σχεδόν απαλλαγμένος από αέριους ρύπους. Η έκθεση των φυτών στα επίπεδα του όζοντος, άρχισε οκτώ ημέρες μετά τη βλάστηση των σπερμάτων και διακόπηκε, δηλ. 157 ημέρες συνολικά, μία ημέρα προτού αφαιρεθούν τα φύλλα, για να υπολογιστεί το εμβαδό τους. Στον πρώτο θάλαμο υπήρχαν τα φυτά μάρτυρες που δέχονταν φιλτραρισμένο αέρα (απαλλαγμένο από αέριους ρύπους μεταξύ των οποίων και το όζον). Στο δεύτερον θάλαμο τα φυτά δέχονταν 100 ppb όζοντος, επί επτά συνεχείς ώρες το 24ωρο, κατά τη διάρκεια του φωτισμού τους με τεχνητό ορατό φως. Η συγκέντρωση των 100ppb όζοντος, προκάλεσε στα φυτά σε σχέση με τα φυτά του μάρτυρα, τα παρακάτω: α) Τα ορατά συμπρώματα από την επίδραση του όζοντος ήταν λευκές νεκρωτικές κηλίδες στις μεσονεύριες περιοχές των φύλλων β)Αύξησε τον αριθμό των στομάτων, τον αριθμό των επιδερμικών κυττάρων και την κιτρινίλα των ινών του βαμβακιού. γ) Δεν είχε σημαντική επίδραση στο μήκος και στο πλάτος των καταφρακτικών κυττάρων των στομάτων, στον αριθμό των μη αδενωδών τριχών των περιοχών μεταξύ των κύριων νευρώσεων της επιφάνειας των φύλλων και στο περιεχόμενο σε κηρούς της εφυμενίδας των φύλλων. δ) Μείωσε τον αριθμό των μη αδενωδών τριχών των κύριων νευρώσεων της επιφάνειας των φύλλων, το ύψος των φυτών, το περιεχόμενο σε χλωροφύλλη, τον καθαρό ρυθμό φωτοσύνθεσης, ..

Effects of ozone fumigation on cotton (Gossypium hirsutum L.) morphology, anatomy, physiology, yield and qualitative characteristics of fibers

This experiment was conducted to study the effect of high ozone concentrations on two cotton (Gossypium hirsutum L.) cultivars. Two cotton cultivars (Roma nos and Allegria) were exposed to con trol (CF < 4 ppb O(3)) and 100 ppb O(3). Plant expos ore to ozone began eight days after emergence and was interrupted one day before removing the leaves, to calculate the leaf area. Plants were exposed to ozone 7 h/day, in closed and controlled-environment chambers, during their illumination with artificial visible light. In comparison to control plants. plants exposed to O(3) showed chlorotic and necrotic patches on their leaves. increased stomatal or epidermal cell density and yellowness of cotton fibers. Elevated ozone concentration did not have a significant effect on stomatal width, total leaf thickness and thickness of histological components of leaves. Exposure to ozone concentration reduced non-glandular hair density of main leaf veins, plant height, mainstem internode length, chlorophyll content, net photosynthetic rate, stomatal conductance and length and area of bracts and petals. Elevated ozone treatment reduced the maximum length of staminal tube, anther number, pollen grain germination, leaf area, leaf dry weight, boll number, raw cotton weight, total branch length, dry weight of the mainstem-branches-bracts-carpophylls and of root dry weight. Furthermore, exposure to O(3) reduced the seed weight, the lint weight. the yield, the ratio of lint weight to seed weight, the fiber strength, the micronaire, the maturity index and the fiber uniformity index values. This study shows chat the exposure to high ozone concentrations mainly affected the rate of photosynthesis. raw cotton weight and strength of cotton fibers. (C) 2009 Elsevier B.V. All rights reserved