Hemodynamic changes during laparoscopic cholecystectomy

Hemodynamics during laparoscopic cholecystectomy under general anesthesia (isoflurane in N2O/O2 (50%)) were investigated in 15 nonobese ASA Class I patients by using invasive hemodynamic monitoring including a flow-directed pulmonary artery catheter. During surgery, intraabdominal pressure was maintained automatically at 14 mm Hg by a CO2 insufflator, and minute ventilation was controlled and adjusted to avoid hypercapnia. Hemodynamics were measured before anesthesia, after the induction of anesthesia, after tilting into 10 degrees head-up position, 5 min, 15 min, and 30 min after peritoneal insufflation, and 30 min after exsufflation. Induction of anesthesia decreased significantly mean arterial pressure and cardiac index (CI). Tilting the patient to the head-up position reduced cardiac preload and caused further reduction of CI. Peritoneal insufflation resulted in a significant increase (+/- 35%) of mean arterial pressure, a significant reduction (+/- 20%) of CI, and a significant increase of systemic (+/- 65%) and pulmonary (+/- 90%) vascular resistances. The combined effect of anesthesia, head-up tilt, and peritoneal insufflation produced a 50% decrease in CI. Administration of increasing concentrations of isoflurane, via its vasodilatory activity, may have partially blunted these hemodynamic changes. These results demonstrate that laparoscopy for cholecystectomy in head-up position results in significant hemodynamic changes in healthy patients, particularly at the induction of pneumoperitoneum.     

Iron acquisition by Helicobacter pylori: importance of human lactoferrin

Helicobacter pylori is known to be an etiologic agent of gastritis and peptic ulcer disease in humans. However, the mechanism by which this organism acquires iron has not been studied. For this investigation, H. pylori was grown in iron-restricted medium. Siderophore production was not detected by chemical assays, and the strains were unable to use enterochelin and pyochelin for growth in low-iron media. Human lactoferrin supported full growth of the bacteria in media lacking other iron sources, but neither human transferrin, bovine lactoferrin, nor hen ovotransferrin served as a source for iron. Since lactoferrin was found in significant amounts in human stomach resections with superficial or atrophic gastritis, the iron acquisition system of H. pylori by the human lactoferrin receptor system may play a major role in the virulence of H. pylori infection.     

Unravelling the fruit microbiome: The key for developing effective biological control strategies for postharvest diseases

Fruit-based diets are recognized for their benefits to human health. The safety of fruit is a global concern for scientists. Fruit microbiome represents the whole microorganisms that are associated with a fruit. These microbes are either found on the surfaces (epiphytes) or in the tissues of the fruit (endophytes). The recent knowledge gained from these microbial communities is considered relevant to the field of biological control in prevention of postharvest fruit pathology. In this study, the importance of the microbiome of certain fruits and how it holds promise for solving the problems inherent in biocontrol and postharvest crop protection are summarized. Research needs on the fruit microbiome are highlighted. Data from DNA sequencing and “meta-omics” technologies very recently applied to the study of microbial communities of fruits in the postharvest context are also discussed. Various fruit parameters, management practices, and environmental conditions are the main determinants of the microbiome. Microbial communities can be classified according to their structure and function in fruit tissues. A critical mechanism of microbial biological control agents is to reshape and interact with the microbiome of the fruit. The ability to control the microbiome of any fruit is a great potential in postharvest management of fruits. Research on the fruit microbiome offers important opportunities to develop postharvest biocontrol strategies and products, as well as the health profile of the fruit.     

Soil compaction: a review of past and present techniques for investigating effects on root growth

Soil compaction has been known to affect root growth for millennia. Root growth in natural soils is complex and soil compaction induces several stresses which may interact simultaneously, including increased soil strength, decreased aeration and reduced hydraulic conductivity. Yet, moderate soil compaction offers some benefits to growing roots by increasing root-soil contact so they can extract adequate resources. Until now, improving our understanding of the specific responses of roots to below-ground stimuli has been difficult. However, the advent of new technologies and practices, including X-ray computed tomography, to provide non-destructive, three-dimensional images of root systems throughout the plant's lifecycle now allows the responses of roots encountering changes in their physical, chemical or biotic environment to be established directly and non-invasively. Previous destructive methods, such as root washing, were incapable of identifying and characterising fine root architectural characteristics as these are inextricably linked to the composition of the soil matrix. X-ray computed tomography coupled with genetic approaches will provide a more comprehensive appreciation of the effect of soil compaction on root growth, and the knowledge required to generate improvements in plant breeding programmes and crop husbandry.     

Inverse method for the dynamical analysis of wall shear rates using three-segment probes in parallel plate rheometer

Mass transfer measurements were conducted on a Parallel Plate Rheometer (PPR) using the limiting diffusion current method, i.e. the polarography technique. The database constructed was exploited for the validation of the inverse method under a well-controlled unsteady shear flow. This method is based on a numerical sequential estimation. It has been applied to determine of the wall shear rate in the upper disk of the PPR. It requires the numerical inversion of the convection diffusion equation in order to apply it to instantaneous mass transfer measurements. This requires the use of electrochemical probe, which allows the determination of the local mass transfer rate for known flow kinematics. A multi-segment electrochemical probe has been used. The directional characteristics of the three-segment probe were highlighted. The directional angle effect and the frequencies of oscillations effect were studied in order to test the robustness of the inverse method within the presence of such factors. The obtained results demonstrate that the inverse method allows a good determination of the shear rate, which follows the experimental one for different cases tested in a satisfactory way.     

Securing fruit production: Opportunities from the elucidation of the molecular mechanisms of postharvest fungal infections

Fruit-based diets have been adopted by the public worldwide because of their nutritional value. Many advances have also been made in the elucidation of host–pathogen interaction in the postharvest phase of fruits, in the hope of improving the management of diseases caused by pathogenic molds. In this study, we presented the molecular mechanisms by which pathogenic mold infects fruit in the postharvest phase, and focused on the knowledge gained from recent molecular techniques such as differential analysis of gene expression, targeted insertion, and mutagenesis. Current postharvest pathogenic fungal control strategies were then examined on the basis of their mechanisms for altering the infection process in order to explore new perspectives for securing fruit production. We found that biotechnological advances have led to an understanding of the new basic molecular processes involved in fruit fungal infection and to the identification of new genes, proteins and key factors that could serve as ideal targets for innovative antifungal strategies. In addition, the most commonly used steps to evaluate an approach to disrupt the fruit fungal infection process are mainly based on the inhibition of mycelial growth, spore germination, disruption of Adenosine triphosphate (ATP) synthesis, induction of oxidative stress, cell wall membrane damage, and inhibition of key enzymes. Finally, the alteration of the molecular mechanisms of signaling and response pathways to infection stimulation should also guide the development of effective control strategies to ensure fruit production.     

Modeling dynamic functioning of rectangular photobioreactors in solar conditions

A generic model for the simulation of solar rectangular photobioreactors (PBR) is presented. It combines the determination of the time‐varying solar radiation intercepted by the process with the theoretical framework necessary for PBR simulation, namely modeling of the radiant light energy transport inside the culture volume, and its local coupling to photosynthetic growth. Here, the model is applied to illustrate the full dependency of PBR behavior on solar illumination regimes, which results in a complex, transient response. Effects of day–night cycles, culture harvesting, and the interdependency of physical (light) and biological (growth) kinetics are discussed. It is shown that PBR productivity is the result not only of light intercepted on the illuminated surface but also of light attenuation conditions inside the bulk culture as influenced by incident angle and beam/diffuse distribution of solar radiation. Results are presented for a location in France for 2 months representative of summer and winter. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

Chemical Synthesis and Isolation of Trans‐Palmitoleic Acid (Trans‐C16:1 n‐7) Suitable for Nutritional Studies

Trans‐palmitoleic acid (trans‐9 C16:1, or trans‐C16:1 n‐7, TPA) is typically found in ruminant‐derived foods (milk and meat). Of note, previous epidemiological studies associated high levels of circulating TPA with a lower risk of type 2 diabetes and metabolic syndrome in humans. At the current time, TPA intakes in humans are ensured by ruminant‐derived foods. However, due to the very low commercial availability of TPA, there are no supplementation studies carried out so far. Therefore, the ability for dietary TPA to prevent type 2 diabetes and metabolic syndrome has never been experimentally assessed. Here, a method (among others) to get dozens of grams of pure TPA as ethyl ester, to perform dedicated supplementation studies, is reported. For that purpose, it starts from food sources containing high amounts of cis‐palmitoleic acid (cis‐9 C16:1, or cis‐C16:1 n‐7, CPA), dealing with fatty acids ethyl esters all along the experiment. CPA is purified with flash liquid chromatography, then submitted to a cis/trans isomerization step. Finally, TPA is separated from CPA by low‐temperature crystallization in methanol. The final product is fully characterized by ¹H and ¹³C nuclear magnetic resonance spectrometry. It is possible to produce ≈70 g of 85%‐purity TPA suitable for nutritional studies. Practical Applications: The synthesized trans‐palmitoleic acid may serve for supplementation (or nutritional) studies aiming at unravelling its physiological impacts suggested by epidemiological work. Depending on the amount of synthesized trans‐palmitoleic acid, one may carry out nutritional studies on rodents or even on humans.     

Investigations in an external-loop airlift photobioreactor with annular light chambers and swirling flow

Photosynthetic microorganisms could serve as valuable compounds, but also for environmental applications. Their production under controlled conditions implies to design specific reactors, named photobioreactors, in which light supply is the main constraint. This paper was devoted to an original external-loop airlift photobioreactor (PBR) with annular light chambers in which a swirling motion was induced. The aim was to characterize this novel geometrical configuration in terms of gas-liquid hydrodynamics, and to test its potentiality for algal cultures. This PBR consisted of two identical columns connected by flanges defining tangential inlets, each column being made of two transparent concentric tubes (6 L in liquid volume, 50 m⁻¹ in specific illuminated area). Firstly, the global flow characteristics (circulation and mixing times) were determined by a tracer method and modelled by an axial dispersed plug flow with complete recirculation (Péclet number). By means of a double optical probe, both local and global time-averaged parameters of the gas phase were measured, namely void fraction, bubble velocity, frequency and size. The gas-liquid mass transfer were also characterized, in tap water and in culture medium, by measuring overall volumetric mass transfer coefficients. In a second time, cultures of the microalga Chlamydomonas reinhardtii were run in batch mode. The variations of biomass concentration and pigment content with time from inoculation were successfully obtained. All these findings highlighted: (i) some significant differences in terms of gas-liquid hydrodynamics between the present PBR and the usual airlift systems, (ii) the interest of this configuration for algal cultures, even if complementary studies and technological improvements are still required for definitively validating its scale-up.