Quantifying growth mechanics of living, growing plant cells in situ using microrobotics

Plant cell growth is a fundamental process during plant development and the developmental biology society has studied cell growth from various aspects using physiological, biochemical, genetic, mathematical and modelling approaches. Recent advances in the field of biology demonstrate a need for investigation and quantification of the mechanics of growth at individual cellular levels. Here, we describe a microrobotic system capable of performing automated mechanical characterisation of living plant cells in situ as these cells proliferate and grow. The microrobotic measurement system employs a single-axis capacitive MEMS microforce sensor, a multi-axis positioning system with position feedback, a high-resolution optical microscope and a custom-user interface for the guiding of the automated measurement process. The system has been applied to measure mechanical properties of Lilium pollen tubes approximately 20--m wide. The measurements were performed in growth medium, and the observed growth rate of the pollen tubes is about 20--m per minute. For the mechanical characterisation of pollen tubes, nano-Newton level loads and nanometric indentations are applied. The force-deformation data obtained show a difference in stiffness from the tip to the apex demonstrating that the developed measurement system is a promising tool for better understanding the mechanics of plant cell growth

Effect of perioperative immuno-enhanced enteral nutrition on inflammatory response, nutritional status, and outcomes in head and neck cancer patients undergoing major surgery

Administration of imunno-enhanced nutritional support may decrease postoperative morbidity, mortality, and infectious complications in cancer patients. The aim of this study was to verify that perioperative enteral diet, enriched with the nutrients arginine, ribonucleic acid (RNA), and ω-3 fatty acids improves outcomes of head and neck cancer patients undergoing major surgery. Forty patients with squamous cell carcinoma of the head and neck were studied. Group 1 received no preoperative nutritional support, whereas Group 2 received an oral formula with nutrients arginine, RNA, and ω-3 fatty acids. After surgery, Group 1 received a standard enteral formula, whereas Group 2 received an enriched enteral formula. Albumin (g/dl), prealbumin, fibrinogen, CRP, Il-6, and TNFa were measured 5 days before and 8 days after surgery. No statistically significant difference was observed for all the evaluated markers between postoperative and preoperative levels for both groups. The rate of complications was significantly reduced in the total number of patients receiving immunonutrition and in the particular subgroup of well-nourished patients receiving an immuno-enhanced diet. Perioperative enteral immuno-enhanced feeding in head and neck cancer patients undergoing major surgery may influence the postoperative outcomes by reducing the frequency rate of infections and wound complications. Copyright © 2010, Taylor & Francis Group, LLC

Cellular Force Microscopy for in Vivo Measurements of Plant Tissue Mechanics1[W][OA]

Although growth and morphogenesis are controlled by genetics, physical shape change in plant tissue results from a balance between cell wall loosening and intracellular pressure. Despite recent work demonstrating a role for mechanical signals in morphogenesis, precise measurement of mechanical properties at the individual cell level remains a technical challenge. To address this challenge, we have developed cellular force microscopy (CFM), which combines the versatility of classical microindentation techniques with the high automation and resolution approaching that of atomic force microscopy. CFM’s large range of forces provides the possibility to map the apparent stiffness of both plasmolyzed and turgid tissue as well as to perform micropuncture of cells using very high stresses. CFM experiments reveal that, within a tissue, local stiffness measurements can vary with the level of turgor pressure in an unexpected way. Altogether, our results highlight the importance of detailed physically based simulations for the interpretation of microindentation results. CFM’s ability to be used both to assess and manipulate tissue mechanics makes it a method of choice to unravel the feedbacks between mechanics, genetics, and morphogenesis