Reinforcement versus Fluidization in Cytoskeletal Mechanoresponsiveness

Every adherent eukaryotic cell exerts appreciable traction forces upon its substrate. Moreover, every resident cell within the heart, great vessels, bladder, gut or lung routinely experiences large periodic stretches. As an acute response to such stretches the cytoskeleton can stiffen, increase traction forces and reinforce, as reported by some, or can soften and fluidize, as reported more recently by our laboratory, but in any given circumstance it remains unknown which response might prevail or why. Using a novel nanotechnology, we show here that in loading conditions expected in most physiological circumstances the localized reinforcement response fails to scale up to the level of homogeneous cell stretch; fluidization trumps reinforcement. Whereas the reinforcement response is known to be mediated by upstream mechanosensing and downstream signaling, results presented here show the fluidization response to be altogether novel: it is a direct physical effect of mechanical force acting upon a structural lattice that is soft and fragile. Cytoskeletal softness and fragility, we argue, is consistent with early evolutionary adaptations of the eukaryotic cell to material properties of a soft inert microenvironment.

Early versus delayed application of Thomas splints in patients with isolated femur shaft fractures: The benefits quantified.

AIMS: To investigate and quantify the clinical benefits of early versus delayed application of Thomas splints in patients with isolated femur shaft fractures. MATERIALS AND METHODS: Level IV retrospective clinical and radiological analysis of patients presenting from January to December 2012 at a Level 1 Trauma Unit. All skeletally mature patients with isolated femur shaft fractures independently of their mechanism of injury were included. Exclusion criteria were: ipsilateral fracture of the lower limb, neck and supracondylar femur fractures, periprosthetic and incomplete fractures. Their clinical records were analysed for blood transfusion requirements, pulmonary complications, surgery time, duration of hospital stay and analgesic requirements. RESULTS: A total of 106 patients met our inclusion criteria. There were 74 males and 32 females. Fifty seven (54%) patients were in the 'early splinted' group and 49 patients (46%) were in the 'delayed splinted' group (P>0.05). The need for blood transfusion was significantly reduced in the 'early splinted' group (P=0.04). There was a significantly higher rate of pulmonary complications in the 'delayed splinted' group (P=0.008). All other parameters were similar between the two groups. CONCLUSION: The early application of Thomas splints for isolated femur fractures in non-polytraumatised patients has a clinically and statistically significant benefit of reducing the need for blood transfusions and the incidence of pulmonary complications.

Gleevec, an Abl family inhibitor, produces a profound change in cell shape and migration (in press)

The issue of how contractility and adhesion are related to cell shape and migration pattern remains largely unresolved. In this paper we report that Gleevec (Imatinib), an Abl family kinase inhibitor, produces a profound change in the shape and migration of rat bladder tumor cells (NBTII) plated on collagen-coated substrates. Cells treated with Gleevec adopt a highly spread D-shape and migrate more rapidly with greater persistence. Accompanying this more spread state is an increase in integrin-mediated adhesion coupled with increases in the size and number of discrete adhesions. In addition, both total internal reflection fluorescence microscopy (TIRFM) and interference reflection microscopy (IRM) revealed a band of small punctate adhesions with rapid turnover near the cell leading margin. These changes led to an increase in global cell-substrate adhesion strength, as assessed by laminar flow experiments. Gleevec-treated cells have greater RhoA activity which, via myosin activation, led to an increase in the magnitude of total traction force applied to the substrate. These chemical and physical alterations upon Gleevec treatment produce the dramatic change in morphology and migration that is observed.

Barrier-protective effects of activated protein C in human alveolar epithelial cells

Acute lung injury (ALI) is a clinical manifestation of respiratory failure, caused by lung inflammation and the disruption of the alveolar-capillary barrier. Preservation of the physical integrity of the alveolar epithelial monolayer is of critical importance to prevent alveolar edema. Barrier integrity depends largely on the balance between physical forces on cell-cell and cell-matrix contacts, and this balance might be affected by alterations in the coagulation cascade in patients with ALI. We aimed to study the effects of activated protein C (APC) on mechanical tension and barrier integrity in human alveolar epithelial cells (A549) exposed to thrombin. Cells were pretreated for 3 h with APC (50 mg/ml) or vehicle (control). Subsequently, thrombin (50 nM) or medium was added to the cell culture. APC significantly reduced thrombin-induced cell monolayer permeability, cell stiffening, and cell contraction, measured by electrical impedance, optical magnetic twisting cytometry, and traction microscopy, respectively, suggesting a barrier-protective response. The dynamics of the barrier integrity was also assessed by western blotting and immunofluorescence analysis of the tight junction ZO-1. Thrombin resulted in more elongated ZO-1 aggregates at cell-cell interface areas and induced an increase in ZO-1 membrane protein content. APC attenuated the length of these ZO-1 aggregates and reduced the ZO-1 membrane protein levels induced by thrombin. In conclusion, pretreatment with APC reduced the disruption of barrier integrity induced by thrombin, thus contributing to alveolar epithelial barrier protection.

High-resolution computed tomography and histopathological findings in hypersensitivity pneumonitis: a pictorial essay

Abstract Hypersensitivity pneumonitis is a diffuse interstitial and granulomatous lung disease caused by the inhalation of any one of a number of antigens. The objective of this study was to illustrate the spectrum of abnormalities in high-resolution computed tomography and histopathological findings related to hypersensitivity pneumonitis. We retrospectively evaluated patients who had been diagnosed with hypersensitivity pneumonitis (on the basis of clinical-radiological or clinical-radiological-pathological correlations) and had undergone lung biopsy. Hypersensitivity pneumonitis is clinically divided into acute, subacute, and chronic forms; high-resolution computed tomography findings correlate with the time of exposure; and the two occasionally overlap. In the subacute form, centrilobular micronodules, ground-glass opacities, and air trapping are characteristic high-resolution computed tomography findings, whereas histopathology shows lymphocytic inflammatory infiltrates, bronchiolitis, variable degrees of organizing pneumonia, and giant cells. In the chronic form, high-resolution computed tomography shows traction bronchiectasis, honeycombing, and lung fibrosis, the last also being seen in the biopsy sample. A definitive diagnosis of hypersensitivity pneumonitis can be made only through a multidisciplinary approach, by correlating clinical findings, exposure history, high-resolution computed tomography findings, and lung biopsy findings.

Robotic-Assisted Surgery Improves the Quality of Total Mesorectal Excision for Rectal Cancer Compared to Laparoscopy: Results of a Case-Controlled Analysis.

BACKGROUND: The use of a robotic surgical system is claimed to allow precise traction and counter-traction, especially in a narrow pelvis. Whether this translates to improvement of the quality of the resected specimen is not yet clear. The aim of the study was to compare the quality of the TME and the short-term oncological outcome between robotic and laparoscopic rectal cancer resections. METHODS: 20 consecutive robotic TME performed in a single institution for rectal cancer (Rob group) were matched 1:2 to 40 laparoscopic resections (Lap group) for gender, body mass index (BMI), and distance from anal verge on rigid proctoscopy. The quality of TME was assessed by 2 blinded and independent pathologists and reported according to international standardized guidelines. RESULTS: Both samples were well matched for gender, BMI (median 25.9 vs. 24.2 kg/m(2), p = 0.24), and level of the tumor (4.1 vs. 4.8 cm, p = 0.20). The quality of the TME was better in the Robotic group (complete TME: 95 vs. 55 %; p = 0.0003, nearly complete TME 5 vs. 37 %; p = 0.04, incomplete TME 0 vs. 8 %, p = 0.09). A trend for lower positive circumferential margin was observed in the Robotic group (10 vs. 25 %, p = 0.1). CONCLUSIONS: These results suggest that robotic-assisted surgery improves the quality of TME for rectal cancer. Whether this translates to better oncological outcome needs to be further investigated.

Previsão das propriedades físicas do papel kraft por espectroscopia no infravermelho próximo (NIR) e regressão por mínimos quadrados parciais (PLS)

The main objective of the present work is represented by the characterization of the physical properties of industrial kraft paper (i.e. transversal and longitudinal tear resistance, transversal traction resistance, bursting or crack resistance, longitudinal and transversal compression resistance (SCT (Compressive Strength Tester) and compression resistance (RCT-Ring Crush Test)) by near infrared spectroscopy associated to partial least squares regression. Several multivariate models were developed, many of them with high prevision capacity. In general, low prevision errors were observed and regression coefficients that are comparable with those provided by conventional standard methodologies.

Design and analysis of a transversal-flux switched-reluctance-linear-machine pole-pair

The Switched Reluctance technology is probably best suited for industrial low-speed or zerospeed applications where the power can be small but the torque or the force in linear movement cases might be relatively high. Because of its simple structure the SR-motor is an interesting alternative for low power applications where pneumatic or hydraulic linear drives are to be avoided. This study analyses the basic parts of an LSR-motor which are the two mover poles and one stator pole and which form the “basic pole pair” in linear-movement transversal-flux switchedreluctance motors. The static properties of the basic pole pair are modelled and the basic design rules are derived. The models developed are validated with experiments. A one-sided one-polepair transversal-flux switched-reluctance-linear-motor prototype is demonstrated and its static properties are measured. The modelling of the static properties is performed with FEM-calculations. Two-dimensional models are accurate enough to model the static key features for the basic dimensioning of LSRmotors. Three-dimensional models must be used in order to get the most accurate calculation results of the static traction force production. The developed dimensioning and modelling methods, which could be systematically validated by laboratory measurements, are the most significant contributions of this thesis.

Luistonestojärjestelmän ja elektronisen tasauspyörästön suunnittelu ja implementointi hybridityökoneympäristöön

Ympäristörasituksen vähentäminen, tiukkenevat päästörajat ja ehtyvät öljyvarat ovat ajaneet kulkuvälineteollisuuden hakemaan uusia vaihtoehtoja ajoneuvojen energiatehokkuuden kehittämiseksi. Hybriditeknologia tarjoaa ratkaisuja kustannustehokkuuden ja ympäristöystävällisyyden parantamiseksi. Hybriditeknologian yleistyessä myös työkoneympäristössä saadaan paitsi kehitettyä energiatehokkaampia ja pienemmillä käyttökustannuksilla olevia työkoneita, niin myös tuotua siviiliajoneuvoista tuttuja turvallisuusominaisuuksia työkoneympäristöön. Perinteisten diesel-moottorien korvaaminen nopeavasteisilla ja tarkasti säädettävillä sähkömoottoreilla tarjoaa mahdollisuuksia toteuttaa tarkempia ja monipuolisempia säätöjärjestelmiä kuin perinteisessä ympäristössä. Tässä diplomityössä suunnitellaan luistonestojärjestelmä ja elektroninen tasauspyörästö hybridityökoneympäristöön. Järjestelmä voi käyttökohteesta riippuen pienentää huomattavasti käyttökustannuksia ja mahdollistaa uusien sovellusten tuomista markkinoille, kuten esimerkiksi kääntymisen avustaminen differentiaalisella ohjauksella.

Luistonestojärjestelmän ja elektronisen tasauspyörästön testaus ja implementointi hybridityökoneympäristöön

Työssä toteutettiin C-kielellä luistonestojärjestelmä ja elektroninen tasauspyörästö Simulinkmallien pohjalta hybridityökoneeseen. Hybridityökoneen sähkökäytöt mahdollistavat tarkan vääntömomentin säädön, joka mahdollistaa työssä kuvatun kaltaisen järjestelmän toteuttamisen. Toteutettua järjestelmää simuloitiin MeVEA Oy:n ajoneuvomallinnukseen kehitetyssä simulaattorissa. Lisäksi järjestelmästä kehitettiin Visedo Oy:n sähkökäyttösimulaattoriin sopiva versio, jota testattiin Visedon sähkökäyttöjä simuloivan ohjelman kanssa. Simulointituloksien mukaan luistonesto estää vetäviä pyöriä luistamasta liukkaalla alustalla eikä toisaalta vähennä aiheetta kuljettajan asettamaa vääntömomenttia. Myös sähköinen tasauspyörästö toimi kuten oli suunniteltu. Työssä kehitetty luistonesto tarvitsee toimiakseen tiedon ajoneuvon kokonaismassasta, joten työssä kehitettiin myös tapa ajoneuvon massan estimoimiseksi ajoneuvon kiihdyttäessä. Massan estimointia testattiin pitävällä ja liukkaalla alustalla. Massan estimointi toimi simulaattoriympäristössä hyvällä tarkkuudella.

Seeder-fertilizer machine: energetic demand as a function of vegetal covering handling and manure deposition shank depth in no-tillage system

The purpose of this work was evaluating the energetic demand of a seeder-fertilizer machine as a function of the type and handling of vegetal covering culture and of the fertilizer deposition shank depth. A Valtra BM100 tractor was used implemented to pull a high precision seeder-fertilizer machine with four ranks of seeding, spaced 0.9 m for maize culture. Experiment was conducted with design in randomized blocks in factorial plots, in the Laboratory of Machines and Agricultural Mechanization experimental area (LAMMA) of UNESP-Jaboticabal, using two covering cultures (black-mucuna and crotalaria), three handlings of this covering, two mechanical (straw crusher and roller knife) and one chemical (pulverization of herbicide), performed 120 days after seeding of covering cultures and three depths of fertilizer deposition shank, completing 18 treatments, with four repetitions, totaling 72 observations. Parameters of displacement speed, gliding, force on traction bar, peak force, power on pulling bar and fuel consumption were evaluated. It was possible to conclude that force on traction bar was less for depths of 0.11 and 0.14 m of fertilizer plough shank, the same occurring for peak force, power on traction bar and volumetric consumption. The specific consumption was lower at a depth of 0.17 m of fertilizer plough shank. Covering cultures and their handlings did not interfere in the performance of machines under inquiry.

Operational characteristics of four metering systems for agricultural fertilizers and amendments

The use of fertilizers and solid amendments in agriculture generates special interest for their effect on crop productivity, as well as for their environmental impact. The efficient use of these products demands knowing their physical and mechanical properties, the storing conditions effect and the operational characteristics of the metering systems used in the fertilizing equipment. In this context, the present study was developed with the purpose of evaluating the operational characteristics of different fertilizing metering systems and to determine the adequate metering system-product operational parameters, using powder lime, powder gypsum, granular 10-30-10 (N-P-K), and granular urea. Operational differences were established among four types of commercial fertilizer metering systems, including wire auger, star-shaped feed wheel, feed screw and ridged traction wheel. The study found that the unloading rate depends directly on the fertilizer metering system's rotating speed and is affected by particle size, repose angle, bulk density and moisture content of the applied product. The wire auger and star-shaped feed wheel metering systems were adequate for the distribution of powder products and the feed screw for granulated fertilizers. Furthermore, theoretical and experimental characteristic equations were established, defining curves for calibration and handling of the products plus the rotating speed range in which a better distributing behavior was achieved.

Evaluation of tractive performance of four agricultural tractors in laterally inclined terrain

The present work aimed to evaluate the tractive performance of four agricultural tractors with auxiliary front traction in function of six lateral inclinations in a lateral track of trials, which belongs to the Agronomic Sciences Faculty from the São Paulo State University, Campus of Botucatu. The lateral inclinations were 0; 5; 10; 15; 20 and 25 degrees. In all of these situations, the tractors operated with predetermined load of an imposed traction to the pulled tractor of 40 kN in the inclination of 0 degrees. Hence a delineation in random blocks was used, considering six inclinations and four tractors, and with three repetitions for each treatment. The analyzed variables were slippage, tractive force, hourly fuel consumption, and speed. It was concluded that the pneumatic tire configurations influenced in the tractive performance of the tractors, as they increased the lateral inclinations of the terrain.

Mechanical behavior of 'Niagara Rosada' grape berry detachment

The 'Niagara Rosada' grape is the main Brazilian table grape belonging to the Labrusca family. It develops medium, cylindrical and compact bunches with berries presenting a pinkish skin and a foxy flavor that is valued in the Brazilian market. These berries are tender and have a pedicel-berry connection provided by the vascular bundles and surrounding skin. This cultivar is very susceptible to berry drop mainly caused by vibration and senescence. The objective of this study was to evaluate the temporal mechanical behavior of the pedicel-berry detachment, using resistance indexes extracted from traction force-deformation curves. Test results showed two different detachment types. In the first one, which exhibited higher average resistance, a considerable portion of the vascular bundle came out attached to the pedicel and in the second type; the vascular bundle was retained inside the berry. The proposed indexes based on maximum detachment force, force at 0.2; 0.5; 1.0 and 1.2 mm, and maximum force to corresponding deformation ratio did not discriminate the senescence of the berry.

Fuel consumption of a tractor in function of wear, of ballasting and tire inflation pressure

When using appropriate inflation pressures and load capacity (ballast), it may obtain a higher yield and prolongation of the life of the tire, besides it may minimize the problems of loss of traction, increased slippage and fuel consumption. This study aimed to evaluate the fuel consumption of a tractor operating with new and worn tires in three conditions of ballasting and three inflation pressures, when driving on compacted soil with vegetation cover. The experiment was conducted at the experimental unit from the Department of Animal Science, Federal University of Lavras, state of Minas Gerais, Brazil, in an agricultural soil compacted by cattle trampling and with vegetation cover. It was used a tractor 4x2 with front wheel assist, of a 65.62 kW engine power. The tires were of R1 type, diagonal (front: 12.4 to 24; and rear: 18.4 to 30), the average height of the clutches of the new tires were 0.3 and 0.35 m for front and rear tires, respectively, and for the worn tires were 0.018 and 0.0045 m, for the front and the rear tires, respectively. The results showed advantages for the tractor equipped with new tires.