Tumor-on-a-chip for integrating a 3D tumor microenvironment: chemical and mechanical factors.

Tumor progression, including metastasis, is significantly influenced by factors in the tumor microenvironment (TME) such as mechanical force, shear stress, chemotaxis, and hypoxia. At present, most cancer studies investigate tumor metastasis by conventional cell culture methods and animal models, which are limited in data interpretation. Although patient tissue analysis, such as human patient-derived xenografts (PDX), can provide important clinical relevant information, they may not be feasible for functional studies as they are costly and time-consuming. Thus, in vitro three-dimensional (3D) models are rapidly being developed that mimic TME and allow functional investigations of metastatic mechanisms and drug responses. One of those new 3D models is tumor-on-a-chip technology that provides a powerful in vitro platform for cancer research, with the ability to mimic the complex physiological architecture and precise spatiotemporal control. Tumor-on-a-chip technology can provide integrated features including 3D scaffolding, multicellular culture, and a vasculature system to simulate dynamic flow in vivo. Here, we review a select set of recent achievements in tumor-on-a-chip approaches and present potential directions for tumor-on-a-chip systems in the future for areas including mechanical and chemical mimetic systems. We also discuss challenges and perspectives in both biological factors and engineering methods for tumor-on-a-chip progress. These approaches will allow in the future for the tumor-on-a-chip systems to test therapeutic approaches for individuals through using their cancerous cells gathered through approaches like biopsies, which then will contribute toward personalized medicine treatments for improving their outcomes.

Association between biochemical control and comorbidities in patients with acromegaly: an Italian longitudinal retrospective chart review study.

PURPOSE: Achieving biochemical control (normalization of insulin-like growth factor-1 [IGF-1] and growth hormone [GH]) is a key goal in acromegaly management. However, IGF-1 and GH fluctuate over time. The true potential impact of time-varying biochemical control status on comorbidities is unclear and relies on multiple, longitudinal IGF-1 and GH measurements. This study assessed the association between time-varying biochemical control status and onset of selected comorbidities in patients with acromegaly. METHODS: Medical charts of adults with confirmed acromegaly and ≥ 6 months of follow-up at an Italian endocrinology center were reviewed. Patients were followed from the first diagnosis of acromegaly at the center until loss to follow-up, chart abstraction, or death. Biochemical control status was assessed annually and defined as IGF-1 ≤ the upper limit of normal, or GH ≤ 2.5 µg/L in the few cases where IGF-1 was unavailable. Time-varying Cox models were used to assess the association between biochemical control status and comorbidities. RESULTS: Among 150 patients, 47% were female, average age at diagnosis was 43.1, and mean length of follow-up was 10.4 years. Biochemical control was significantly associated with a lower hazard of diabetes (HR = 0.36, 95% CI 0.15; 0.83) and cardiovascular system disorders (HR = 0.54, 95% CI 0.31; 0.93), and a higher hazard of certain types of arthropathy (HR = 1.68, 95% CI 1.04; 2.71); associations for other comorbidities did not reach statistical significance. CONCLUSION: Results further support the importance of achieving biochemical control, as this may reduce the risk of high-burden conditions, including diabetes and cardiovascular system disorders. The association for arthropathy suggests irreversibility of this impairment. Due to limitations, caution is required when interpreting these results.

Can real-time polymerase chain reaction allow a faster recovery of hospital activity in cases of an incidental discovery of carbapenemase-producing Enterobacteriaceae and vancomycin-resistant Enterococci carriers?

BACKGROUND: Detection of faecal carriers of carbapenemase-producing Enterobacteriaceae (CPE) and vancomycin-resistant Enterococci (VRE) has become a routine medical practice in many countries. In an outbreak setting, several public health organizations recommend three-weekly rectal screenings to rule-out acquisition in contact patients. This strategy, associated with bed closures and reduction of medical activity for a relatively long time, seems costly. AIM: The objective of this study was to test the positive and negative predictive values of reverse transcription polymerase chain reaction (RT-PCR; GeneXpert®) carried-out at Day 0, compared with conventional three-weekly culture-based rectal screenings, in identifying, among contact patients, those who acquired CPE/VRE. METHODS: A multicentre retrospective study was conducted from January2015 to October2018. All contact patients (CPs) were included identified from index patients (IPs) colonized or infected with CPE/VRE, incidentally discovered. Each CP was investigated at Day 0 by PCR (GeneXpert®), and by the recommended three-weekly screenings. FINDINGS: Twenty-two IPs and 159 CPs were included. An average of 0.77 secondary cases per patient was noted, with a mean duration of contact of 10 days (range 1-64). Among the 159 CPs, 16 (10%) had a CPE/VRE-positive culture during the monitoring period. Rectal screenings were positive at Day 0 (10 patients), Day 7 (two patients), Day 14 (four patients). Thirteen of 16 patients with positive culture had a positive PCR at Day 0. Overall, a concordance of 97.5% (155/159) was observed between the three-weekly screenings and Day 0 PCR results. When performed on CPs at Day 0 of the identification of an IP, PCR (GeneXpert®) allowed the reduction in turnaround time by five to 27 days, compared to three-weekly screenings. Positive predictive value and negative predictive value were 100% and 98%, respectively. CONCLUSIONS: The use of RT-PCR (GeneXpert®) can avoid the three-weekly rectal samplings needed to rule-out acquisition of CPE/VRE.

Author Correction: Mimicking Embedded Vasculature Structure for 3D Cancer on a Chip Approaches through Micromilling.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

Mimicking Embedded Vasculature Structure for 3D Cancer on a Chip Approaches through Micromilling.

The ability for cells to sense and respond to microenvironmental signals is influenced by their three dimensional (3D) surroundings, which includes the extracellular matrix (ECM). In the 3D environment, vascular structures supply cells with nutrients and oxygen thus affecting cell responses such as motility. Interpretation of cell motility studies though is often restricted by the applied approaches such as 2D conventional soft lithography methods that have rectangular channel cross-sectional morphology. To better simulate cell responses to vascular supply in 3D, we developed a cell on a chip system with microfluidic channels with curved cross-sections embedded within a 3D collagen matrix that emulates anatomical vasculature more closely than inorganic polymers, thus to mimic a more physiologically relevant 3D cellular environment. To accomplish this, we constructed perfusable microfluidic channels by embedding sacrificial circular gelatin vascular templates in collagen, which were removed through temperature control. Motile breast cancer cells were pre-seeded into the collagen matrix and when presented with a controlled chemical stimulation from the artificial vasculature, they migrated towards the vasculature structure. We believe this innovative vascular 3D ECM system can be used to provide novel insights into cellular dynamics during multidirectional chemokineses and chemotaxis that exist in cancer and other diseases.

[Infection control practices while performing prostate biopsies in France: A CIAFU survey]. / Maîtrise du risque infectieux entourant la réalisation des biopsies de prostate en France : une enquête du Comité d'infectiologie de l'AFU.

In 2008, the French Public Health Committee admitted that associating ultrasound probe protection, and related precautions, and low-level disinfection would be equivalent to the intermediate level disinfection. In 2010, the French Urology Association (AFU) updated guidelines regarding trans-rectal prostate biopsies, namely preventive measures related to cross-transmission of infections. We report an evaluation of compliance to them, driven in 2016 by AFU's infection committee. Although not recommended, almost one third of the urologists still perform biopsies under general anesthesia, and two thirds of them ask for a urine culture before biopsies. Several improvements are still needed: sterilization of needle guide should always be done when not of single use, the ultrasonography gel should be sterile, probes protection should be EC labeled, and compliance to probe processing between two patients should increase. Most of urologists happened to experience blood or feces contamination of probes. Less than half of probes are entirely floodable, and when intermediate level disinfection is done, glutaraldehyde is still referred as disinfectant by one third of the urologists. LEVEL OF EVIDENCE: 4.

Geometric effects in microfluidics on heterogeneous cell stress using an Eulerian-Lagrangian approach.

The response of individual cells at the micro-scale in cell mechanics is important in understanding how they are affected by changing environments. To control cell stresses, microfluidics can be implemented since there is tremendous control over the geometry of the devices. Designing microfluidic devices to induce and manipulate stress levels on biological cells can be aided by computational modeling approaches. Such approaches serve as an efficient precursor to fabricating various microfluidic geometries that induce predictable levels of stress on biological cells, based on their mechanical properties. Here, a three-dimensional, multiphase computational fluid dynamics (CFD) modeling approach was implemented for soft biological materials. The computational model incorporates the physics of the particle dynamics, fluid dynamics and solid mechanics, which allows us to study how stresses affect the cells. By using an Eulerian-Lagrangian approach to treat the fluid domain as a continuum in the microfluidics, we are conducting studies of the cells' movement and the stresses applied to the cell. As a result of our studies, we were able to determine that a channel with periodically alternating columns of obstacles was capable of stressing cells at the highest rate, and that microfluidic systems can be engineered to impose heterogenous cell stresses through geometric configuring. We found that when using controlled geometries of the microfluidics channels with staggered obstructions, we could increase the maximum cell stress by nearly 200 times over cells flowing through microfluidic channels with no obstructions. Incorporating computational modeling in the design of microfluidic configurations for controllable cell stressing could help in the design of microfludic devices for stressing cells such as cell homogenizers.

Ogilvie's syndrome-acute colonic pseudo-obstruction.

Ogilvie's syndrome describes an acute colonic pseudo-obstruction (ACPO) consisting of dilatation of part or all of the colon and rectum without intrinsic or extrinsic mechanical obstruction. It often occurs in debilitated patients. Its pathophysiology is still poorly understood. Since computed tomography (CT) often reveals a sharp transition or "cut-off" between dilated and non-dilated bowel, the possibility of organic colonic obstruction must be excluded. If there are no criteria of gravity, initial treatment should be conservative or pharmacologic using neostigmine; decompression of colonic gas is also a favored treatment in the decision tree, especially when cecal dilatation reaches dimensions that are considered at high risk for perforation. Recurrence is prevented by the use of a multiperforated Faucher rectal tube and oral or colonic administration of polyethylene glycol (PEG) laxative. Alternative therapeutic methods include: epidural anesthesia, needle decompression guided either radiologically or colonoscopically, or percutaneous cecostomy. Surgery should be considered only as a final option if medical treatments fail or if colonic perforation is suspected; surgery may consist of cecostomy or manually-guided transanal pan-colorectal tube decompression at open laparotomy. Surgery is associated with high rates of morbidity and mortality.

[Treatment specifics for spontaneous pneumothorax in flight personnel]. / Spécificités de la prise en charge du pneumothorax spontané chez le personnel navigant.

Spontaneous pneumothorax is one cause of aeronautical unfitness in flight personnel, because of the risk of recurrence in flight, making it an issue of flight safety. Specific treatment is required for fighter pilots, pilots flying single-pilot and pilots in professional training: surgical synthesis via video-thoracoscopy is obligatory from the first episode. Considering the exposure to an accumulation of aeronautical factors that are likely to encourage pneumothorax recurrence in flight, it is apical pleurectomy together with abrasion of the remaining pleura and resection of bullae/blebs that is required for fighter pilots to allow them to recover aeronautical fitness unrestrictedly. For all other categories of flight personnel, treatment is no different from that of the common patient. Knowledge of these treatment specifics is essential, to avoid unnecessary systematic surgical indication for all flight personnel, or jeopardise professional fitness in some of them due to inappropriate treatment.

Modeling molecular interactions to understand spatial crowding effects on heterodimer formations.

Molecular crowding occurs when the density of interacting molecules in some reaction system is sufficient to create deviations from traditional mass-action models of chemistry in diffusive systems. While there is a great deal of theory on the influence of molecular crowding on biochemistry in vivo, the effects are highly dependent on specific assumptions about the shapes, volumes, and diffusion properties of the components of an individual system and are thus difficult to predict from first principles. In this study, we use lattice Monte Carlo simulations to examine the effects on a reaction system for two limiting cases of the diffusion behavior of inert crowding agents. In cells, inert molecules might diffuse throughout a solute along with the reactant species by passive diffusion or may be anchored at fixed positions within the solute. We investigate the relative contributions of the two models to crowding effects by examining moving inert particles versus stationery inert particles on the kinetics of a heterodimer assembly system. The two models of inert crowding agents resulted in highly divergent effects on the reactant system. Stationary particles exhibited a bimodal response in the reaction rate curve that was a function of copy number and spatial arrangement and which accelerated the process at conditions not unlike those found in cellular environments. On the other hand, moving inert particles created a well mixed background that had no effect on the reaction process even under extremely compacted conditions. These results may have applications in developing more realistic simulations of reaction chemistry in crowded environments such as living cells.

[The heart and aerobatics]. / Coeur et voltige aérienne.

Aerobatics is an aerial sport which has many physiological constraints, principally cardiovascular, with a risk if not adapted of sudden mid-air incapacity which could jeopardise aviation safety, and thus justifies the selection and surveillance of pilots. The aeronautical constraints during flight are multiple, related to the environment traversed, how the aircraft functions and its movements. Those which cause accelerations (+G in particular) pose the problem of haemodynamic tolerance because they can induce loss of consciousness due to cerebral hypoxia. Tolerance of acceleration varies among individuals; it can be improved with training, certain protective manoeuvres, and is reduced by hypoxia, certain medications, dehydration and heat. Moreover, in aerobatics certain tricks require manoeuvres which reduce this tolerance to +G accelerations. This is the "push-pull" effect (_G acceleration immediately followed by +G acceleration). This leads to a risk of sudden loss of consciousness with a load factor much lower than that which the pilot knows he is capable of tolerating. Besides the haemodynamic effects, the existence of an actual acceleration cardiomyopathy has been suggested but has not been proven in man. Finally, while changes in cardiac rhythm during accelerations are usual and relate to changes in vaso-sympathetic balance, ventricular and supra-ventricular rhythm disturbances are rare and are related to the intensity and duration of the acceleration.

[Right bundle branch block: electrocardiographic and prognostic features]. / Bloc de branche droit: aspects electrocardiographiques et pronostiques.

The electrocardiographic appearances and the significance of right bundle branch block were described at the beginning of the 20th century. Typical appearances include prolongation > 0.12 s of the QRS complex, RR' or rR' or Rr' appearances in V1 and widened S waves in the leads exploring the left ventricle (SI, aVL, V5 and V6). A delay in the appearance of the intrinsic deflection > 0.08 s may also be observed in the right precordial leads and negative T waves with ST depression may be seen in V1 and sometimes in V2. Left axis deviation of the QRS complex greater than - 45 degrees suggests associated left anterior hemiblock. Right axis deviation beyond + 120 degrees is equivocal. The principal differential ECG diagnosis is the Brugada syndrome, a familial arrhythmogenic autosomal dominant cardiomyopathy of variable penetration. This diagnosis is suggested when ECG abnormalities are observed in patients with a personal or family history of sudden death. Right bundle branch block only seems to have haemodynamic consequences in cardiac failure with associated asynchrony of the left ventricle or in certain cases of right ventricular dilatation encountered in congenital heart disease. The prognosis of right bundle branch block in the absence of underlying cardiac disease is good but it may be poor in other cases, particularly coronary artery disease. Moreover, the prognosis of right bundle branch block to complete atrioventricular block is rare in the absence of associated cardiac disease.

Clean oxidation of thiolates to sulfinates in a four-coordinate CoIII complex with a mixed carboxamido N-thiolato S donor set: relevance to nitrile hydratase.

A new [Co(N2(SO2)2)(CNtBu)2](Et4N) complex 6 was prepared from N,N'-(3-mercapto-3-methyl-butyryl)-o-phenylenediamine and completely characterized. While the starting square planar complex [Co(N2S2)](Et4N) 4 was destroyed by dioxirane, the Co ligated thiolates of the six-coordinate intermediate [Co(N2S2)(CNtBu)2](Et4N) complex 5 was readily oxidized to sulfinates with a stoichiometric amount of this oxidant. The resulting complex 6 crystallizes with an octahedral structure. The SO bonds of the SO2 groups are almost equivalent (approximately 1.483 and approximately 1.453 A). The isonitrile is linearly bonded to the cobalt with a Co-C-N angle of 177.5 degrees and a very short C-N(tBu) distance of 1.13 A, which has a triple bond character. As expected for six-coordinate CoIII complexes, 5 and 6 are diamagnetic in agreement with their 1H and 13C NMR spectra. The SO2 IR bands are located at 1210 cm(-1) (v(as)SO2) and 1070 cm(-1) (v(s)SO2), while the CN vibration of the isonitrile is observed at 2170 cm(-1) in 5 and 2210 cm(-1) in 6. Very recently, it has been reported in the literature that oxidation of the coordinated thiolates was required for activity of both Fe and Co nitrile hydratases. Complex 6, with two oxidized thiolates trans to two deprotonated carboxamido nitrogens, is the first to have an in-plane closely related to that of the Co-NHase active site.

[Cardiovascular effects linked to the use of chloroquine]. / Les effets cardiovasculaires liés à l'utilisation de la chloroquine.

The chloroquine is the mainly and most frequently drug used as antimalaric in the world, in spite of the extension of resistance phenomena. Besides, the chloroquine is also commonly indicated in rheumatology and dermatology as a chronic treatment of some connective tissue disease. The chloroquine has three main cardiovascular effect: membrane stabilizer, direct negative inotropic effect and direct arterial vasodilator. Thus, these cardiovascular iatrogenic effects of the chloroquine are important both through their potential frequency and seriousness. Personal clinical cases and medical review enables to identify the main effects, observed either with prophylactic, or curative, or even toxic dosages. The more often, there are some rhythm and conductance disorders, myocardiopathy, even sometimes vasoplegic shocks. A list of the commercial patent medicine including chloroquine enables to be aware, to prevent and to take into account the cardiovascular risks of a treatment newly set or carried on for long years.

Apoptosis of syncytia induced by the HIV-1-envelope glycoprotein complex: influence of cell shape and size.

Cells stably transfected with a lymphotropic HIV-1 Env gene form syncytia when cocultured with CD4(+)CXCR4(+) cells. Heterokaryons then spontaneously undergo apoptosis, while manifesting signs of mitochondrial membrane pemeabilization as well as nuclear chromatin condensation. Modulation of cellular geometry was achieved by growing syncytia on self-assembled monolayers of terminally substituted alkanethiolates designed to control the adhesive properties of the substrates. Spreading of syncytia, induced by culturing them on small circular adhesive islets (diameter 5 microm), placed at a distance that cells can bridge (10 microm), inhibited spontaneous and staurosporin-induced signs of apoptosis, both at the mitochondrial and at the nuclear levels, and allowed for the generation of larger syncytia. Transient cell spreading conferred a memory of apoptosis inhibition which was conserved upon adoption of a conventional cell shape. Limiting syncytium size by culturing them on square-shaped planar adhesive islands of defined size (400 to 2500 microm(2)), separated by nonadhesive regions, enhanced the rate of apoptotic cell death, as indicated by an accelerated permeabilization of the outer mitochondrial membrane, loss of the mitochondrial inner transmembrane potential, and an increased frequency of nuclear apoptosis. In conclusion, external constraints on syncytial size and shape strongly modulate their propensity to undergo apoptosis.

Investigating the secretory pathway of the baculovirus-insect cell system using a secretory green fluorescent protein.

The secretory pathway is important in actively transporting proteins into the extracellular environment of eucaryotic cells. In this study a green fluorescent protein (GFP) mutant engineered to contain a secretion signal was used as a model protein in order to visualize the secretion process inside insect cells. Fluorescent microscopy indicated that significant amounts of secreted green fluorescent protein (sGFP) accumulated in High-Five, Trichoplusia ni, cells following infection with a baculovirus vector containing the gene under the polyhedrin promoter. Laser scanning confocal microscopy was used to reconstruct whole cell images of the infected High-Five cells at multiple days postinfection. While the protein was widely distributed at 2 days postinfection, certain intracellular regions appeared to contain higher or lower concentrations of the sGFP. A layer by layer examination indicated pockets in which sGFP was absent, and these appear to be vesicles that have recently released the sGFP or are not yet accumulating sGFP. By 3 days postinfection, the sGFP in some cells was concentrated in a number of widely dispersed globules, which may represent the vesicle remnants of a deteriorating secretory pathway. In contrast, nonsecreted GFP was more uniformly distributed in the cells than sGFP and did not accumulate in vesicles. In addition to GFP, the lectins wheat germ agglutinin (WGA) and concanavalin A (ConA), which have affinities for sugar residues, were used to examine the secretory pathway. The WGA, which is a Golgi marker, was distributed around the nucleus prior to infection but then was found to be polarized in one region of the cell following the baculovirus infection. The expansion of other cellular compartments following the baculovirus infection may have caused a change in intracellular distribution of the Golgi. While some of the sGFP was found to colocalize with the WGA label, much of the sGFP was outside this Golgi region. In contrast, ConA labeling, which was not as specific as WGA, was found throughout the cell both before and after infection similar to the sGFP distribution. These studies demonstrate that confocal visualization of fluorescent proteins can be used as an in vivo tool for examining secretory processing in insect cells.

Toward model complexes of Co-containing nitrile hydratases: synthesis, complete characterization and reactivity toward ligands such as CN- and NO of the first square planar CoIII complex with two different carboxamido nitrogens and two thiolato sulfur donors.

A [CoIII(N2S2)]NEt4 complex, with two carboxamido nitrogens and two alkylthiolato sulfurs, was prepared from N,N'-(2-thioacetylisobutyryl)-2-aminobenzylamine, and characterized. It crystallizes with a distorted square planar structure including two short Co-N bonds (approximately 1.882 A) and two short Co-S bonds (approximately 2.134 A). The ligand defines an 11-atom chelate, which may be Co ligands in the mean plane of Co-containing nitrile hydratase. The CoIII oxidation state, reversibly reduced at -1.13 V (vs. SCE) and irreversibly oxidized at +1.29 V (vs. SCE) in DMF, is stable over a 2 V potential range. From the temperature dependence of its magnetic susceptibility, cobalt(III) was found to be in an S = 1 triplet ground state, in agreement with the broad resonances observed in its 1H-NMR spectrum. Preliminary spectral studies showed that this complex does not interact with imidazole, H2O or HO-, but binds two CN anions or two NO molecules. The IR spectrum of the dinitrosyl complex exhibits two NO stretches at 1765 and 1820 cm(-1), in the range previously observed for dinitrosylated complexes derived from cobalt(I). This result suggests that, similarly to Fe NHases, Co NHases might readily bind NO.

Efficacy of Dexedrine for maintaining aviator performance during 64 hours of sustained wakefulness: a simulator study.

INTRODUCTION: The efficacy of Dexedrine for sustaining aviator performance despite 64 h of extended wakefulness was investigated. This study was conducted to extend the findings of earlier research that had proven the efficacy of Dexedrine during shorter periods (i.e., 40 h) of sleep deprivation. METHODS: Dexedrine (10 mg) or placebo was given at midnight, 0400, and 0800 hours on two deprivation days in each of two 64-h cycles of continuous wakefulness. Test sessions consisting of simulator flights, electroencephalographic evaluations, mood questionnaires, and cognitive tasks were conducted at 0100, 0500, 0900, 1300, and 1700 hours on both deprivation days. Two nights of recovery sleep separated the first and second 64-h sleep-deprivation cycles. RESULTS: Simulator flight performance was maintained by Dexedrine throughout sleep deprivation. The most benefit occurred at 0500 and 0900 hours (around the circadian trough) on the first deprivation day, but continued throughout 1700 hours (after 58 h awake) on the second day. Dexedrine suppressed slow-wave EEG activity which occurred under placebo after 23 h awake and continued to exert this effect throughout 55 h (and sometimes 59 h) of deprivation. The drug sustained self-perceptions of vigor while reducing fatigue and confusion. Recovery sleep was slightly less restful under Dexedrine. CONCLUSIONS: Dexedrine sustained aviator performance and alertness during periods of extended wakefulness, but its use should be well controlled. Although effective, Dexedrine is no replacement for adequate crew rest management or restful sleep.

Dynamics of individual flexible polymers in a shear flow.

Polymer dynamics are of central importance in materials science, mechanical engineering, biology and medicine. The dynamics of macromolecular solutions and melts in shear flow are typically studied using bulk experimental methods such as light and neutron scattering and birefringence. But the effect of shear on the conformation and dynamics of individual polymers is still not well understood. Here we describe observations of the real-time dynamics of individual, flexible polymers (fluorescently labelled DNA molecules) under a shear flow. The sheared polymers exhibit many types of extended conformation with an overall orientation ranging from parallel to perpendicular with respect to the flow direction. For shear rates much smaller than the inverse of the relaxation time of the molecule, the relative populations of these two main types of conformation are controlled by the rate of the shear flow. These results question the adequacy of assumptions made in standard models of polymer dynamics.