Atomic force microscopy and graph analysis to study the P-cadherin/SFK mechanotransduction signalling in breast cancer cells

Physical forces mediated by cell-cell adhesion molecules, as cadherins, play a crucial role in preserving normal tissue architecture. Accordingly, altered cadherins' expression has been documented as a common event during cancer progression. However, in most studies, no data exist linking pro-tumorigenic signaling and variations in the mechanical balance mediated by adhesive forces. In breast cancer, P-cadherin overexpression increases in vivo tumorigenic ability, as well as in vitro cell invasion, by activating Src family kinase (SFK) signalling. However, it is not known how P-cadherin and SFK activation impact cell-cell biomechanical properties. In the present work, using atomic force microscopy (AFM) images, cell stiffness and cell-cell adhesion measurements, and undirected graph analysis based on microscopic images, we have demonstrated that P-cadherin overexpression promotes significant alterations in cell's morphology, by decreasing cellular height and increasing its area. It also affects biomechanical properties, by decreasing cell-cell adhesion and cell stiffness. Furthermore, cellular network analysis showed alterations in intercellular organization, which is associated with cell-cell adhesion dysfunction, destabilization of an E-cadherin/p120ctn membrane complex and increased cell invasion. Remarkably, inhibition of SFK signaling, using dasatinib, reverted the pathogenic P-cadherin induced effects by increasing cell's height, cell-cell adhesion and cell stiffness, and generating more compact epithelial aggregates, as quantified by intercellular network analysis. In conclusion, P-cadherin/SFK signalling induces topological, morphological and biomechanical cell-cell alterations, which are associated with more invasive breast cancer cells. These effects could be further reverted by dasatinib treatment, demonstrating the applicability of AFM and cell network diagrams for measuring the epithelial biomechanical properties and structural organization.

Computational reverse shoulder prosthesis model: Experimental data and verification

The reverse shoulder prosthesis aims to restore the stability and function of pathological shoulders, but the biomechanical aspects of the geometrical changes induced by the implant are yet to be fully understood. Considering a large-scale musculoskeletal model of the upper limb, the aim of this study is to evaluate how the Delta reverse shoulder prosthesis influences the biomechanical behavior of the shoulder joint. In this study, the kinematic data of an unloaded abduction in the frontal plane and an unloaded forward flexion in the sagittal plane were experimentally acquired through video-imaging for a control group, composed of 10 healthy shoulders, and a reverse shoulder group, composed of 3 reverse shoulders. Synchronously, the EMG data of 7 superficial muscles were also collected. The muscle force sharing problem was solved through the minimization of the metabolic energy consumption. The evaluation of the shoulder kinematics shows an increase in the lateral rotation of the scapula in the reverse shoulder group, and an increase in the contribution of the scapulothoracic joint to the shoulder joint. Regarding the muscle force sharing problem, the musculoskeletal model estimates an increased activity of the deltoid, teres minor, clavicular fibers of the pectoralis major, and coracobrachialis muscles in the reverse shoulder group. The comparison between the muscle forces predicted and the EMG data acquired revealed a good correlation, which provides further confidence in the model. Overall, the shoulder joint reaction force was lower in the reverse shoulder group than in the control group.

[Epidemiology of hip fractures and its social and economic impact. An update for 2014]

Hip fractures (HF) following low-impact trauma are the most visible and dramatic consequences of osteoporosis (OP). It is estimated that within one year after HF, 20 to 30% of the patients die, 50-60% become disabled and only 30-40% fully recover their previous functional levels. Therefore, its medical, societal and economic impact is huge and it is not fully delivered by the event itself, but rather by its consequences. This paper aims to update data published by Branco et al. 2009 about epidemiology and burden of HF, specifically to revise the national data. In Portugal there have been 77,083 HF reported between 2000 and 2008 with increasing numbers with ageing along with due associated refracture and mortality rates. Recent results suggest a slight change at clinical level concerning the pharmacological approach for the treatment of HF, however it is still important to stay alert to the patients' needs and to their bone mineral density losses in order to avoid repeating the occurrence of these events, aiming to generate significant benefits in terms of health outcomes and due public expenditure.

VO₂ kinetics and metabolic contributions during full and upper body extreme swimming intensity

PURPOSE

Our purpose was to characterize the oxygen uptake ([Formula: see text]) kinetics, assess the energy systems contributions and determine the energy cost when swimming front crawl at extreme intensity. Complementarily, we compared swimming full body with upper body only.

METHODS

Seventeen swimmers performed a 100 m maximal front crawl in two conditions: once swimming with full body and other using only the upper propulsive segments. The [Formula: see text] was continuously measured using a telemetric portable gas analyser (connected to a respiratory snorkel), and the capillary blood samples for lactate concentration analysis were collected.

RESULTS

A sudden increase in [Formula: see text] in the beginning of exercise, which continuously rose until the end of the bout (time: 63.82 ± 3.38 s; [Formula: see text]: 56.07 ± 5.19 ml min(-1) kg(-1); [Formula: see text] amplitude: 41.88 ± 4.74 ml min(-1) kg(-1); time constant: 12.73 ± 3.09 s), was observed. Aerobic, anaerobic lactic and alactic pathways were estimated and accounted for 43.4, 33.1 and 23.5 % of energy contribution and 1.16 ± 0.10 kJ m(-1) was the energy cost. Complementarily, the absence of lower limbs lead to a longer time to cover 100 m (71.96 ± 5.13 s), slower [Formula: see text] kinetics, lower aerobic and anaerobic (lactic and alactic) energy production and lower energy cost.

CONCLUSION

Despite the short duration of the event, the aerobic energy contribution covers about 50 % of total metabolic energy liberation, highlighting that both aerobic and anaerobic energy processes should be developed to improve the 100 m swimming performance. Lower limbs action provided an important contribution in the energy availability in working muscles being advised its full use in this short duration and very high-intensity event.

Neonatal extracorporeal membrane oxygenation: Initial experience of Hospital de São João

The purpose of this series is to report the initial ECMO experience of the Neonatal Intensive Care Unit of Hospital de São João. The first three clinical cases are reported. Case report 1: a 39 weeks gestational age girl with severe lung hypoplasia secondary to a bilateral congenital diaphragmatic hernia. Case report 2: a 39 weeks gestational age girl with a right congenital diaphragmatic hernia and a tracheal stenosis. Case report 3: a 34 weeks gestational age boy, with 61 days of life, with a Bordetella pertussis pneumonia, severe pulmonary hypertension, shock, hyperleukocytosis and seizures.

Multibody System of the Upper Limb Including a Reverse Shoulder Prosthesis

The reverse shoulder replacement, recommended for the treatment of several shoulder pathologies such as cuff tear arthropathy and fractures in elderly people, changes the biomechanics of the shoulder when compared to the normal anatomy. Although several musculoskeletal models of the upper limb have been presented to study the shoulder joint, only a few of them focus on the biomechanics of the reverse shoulder. This work presents a biomechanical model of the upper limb, including a reverse shoulder prosthesis, to evaluate the impact of the variation of the joint geometry and position on the biomechanical function of the shoulder. The biomechanical model of the reverse shoulder is based on a musculoskeletal model of the upper limb, which is modified to account for the properties of the DELTA® reverse prosthesis. Considering two biomechanical models, which simulate the anatomical and reverse shoulder joints, the changes in muscle lengths, muscle moment arms, and muscle and joint reaction forces are evaluated. The muscle force sharing problem is solved for motions of unloaded abduction in the coronal plane and unloaded anterior flexion in the sagittal plane, acquired using video-imaging, through the minimization of an objective function related to muscle metabolic energy consumption. After the replacement of the shoulder joint, significant changes in the length of the pectoralis major, latissimus dorsi, deltoid, teres major, teres minor, coracobrachialis, and biceps brachii muscles are observed for a reference position considered for the upper limb. The shortening of the teres major and teres minor is the most critical since they become unable to produce active force in this position. Substantial changes of muscle moment arms are also observed, which are consistent with the literature. As expected, there is a significant increase of the deltoid moment arms and more fibers are able to elevate the arm. The solutions to the muscle force sharing problem support the biomechanical advantages attributed to the reverse shoulder design and show an increase in activity from the deltoid, teres minor, and coracobrachialis muscles. The glenohumeral joint reaction forces estimated for the reverse shoulder are up to 15% lower than those in the normal shoulder anatomy. The data presented here complements previous publications, which, all together, allow researchers to build a biomechanical model of the upper limb including a reverse shoulder prosthesis.