Acoustic levitation and infrared thermography: a sound approach to studying droplet evaporation.

Herein we report a new technique combining acoustic levitation and infrared thermography to directly monitor droplet surface temperatures. Using it, temperature profiles were recorded during the evaporation of deionized water, methanol, n-propanol, and isopropanol. Results support the viability of this inexpensive and easily-accessed technique for studying chemical and physical changes in droplets.

The role of urea in the solubility of cellulose in aqueous quaternary ammonium hydroxide.

We examine the role of water and urea in cellulose solubility in tetrabutylammonium hydroxide (TBAH). Molecular dynamics simulations were performed for several different solvent compositions with a fixed cellulose fraction. For each composition, two simulations were carried out with cellulose fixed in each of the crystalline and the dissolved states. From the enthalpy and the entropy of the two states, the difference in Gibbs free energy (ΔG) and hence the spontaneity is determined. A comparison with solubility experiments showed a strong correlation between the calculated ΔG and the experimental measurements. A breakdown of the enthalpic and entropic contributions reveals the roles of water and urea in solubility. At high water concentration, a drop in solubility is attributed to both increased enthalpy and decreased entropy of dissolution. Water displaces strong IL-cellulose interactions for weaker water-cellulose interactions, resulting in an overall enthalpy increase. This is accompanied by a strong decrease in entropy, which is primarily attributed to both water and the entropy of mixing. Adding urea to TBAH(aq) increases solubility by an addition to the mixing term and by reducing losses in solvent entropy upon dissolution. In the absence of urea, the flexible [TBA]+ ions lose substantial degrees of freedom when they interact with cellulose. When urea is present, it partially replaces [TBA]+ and to a lesser extent OH- near cellulose, losing less entropy because of its rigid structure. This suggests that one way to boost the dissolving power of an ionic liquid is to limit the number of degrees of freedom from the outset.

[Proximal rupture of the hamstring tendon : From clinical presentation to diagnosis and therapy]. / Proximale Ruptur der Ischiocruralsehnen : Von der klinischen Präsentation zu Diagnose und Therapie.

Rupture of the proximal tendon enthesis of the hamstring muscle (ICM) accounts for approximately 10% of all injuries of the ICM. It occurs most commonly in athletes and active middle-aged individuals. The complete rupture of all three tendons in active patients is generally seen as an indication for surgical repair of the tendon enthesis; however, the correct diagnosis is often not reached in a timely manner. This can lead to prolonged symptoms with pain, weakness and neuralgia. Operative treatment consists of anchor repair of the tendons resulting in good clinical outcome in several case series. Good knowledge of the anatomy and operative approach are mandatory to avoid complications as well as compliance with a gradual rehabilitation scheme to allow tendon to bone healing. The main aim of this review is to highlight the typical history, clinical presentation and examination technique to reach an immediate clinical diagnosis which should be confirmed with a magnetic resonance imaging (MRI) scan.

Human Vascular Microphysiological System for in vitro Drug Screening.

In vitro human tissue engineered human blood vessels (TEBV) that exhibit vasoactivity can be used to test human toxicity of pharmaceutical drug candidates prior to pre-clinical animal studies. TEBVs with 400-800 µM diameters were made by embedding human neonatal dermal fibroblasts or human bone marrow-derived mesenchymal stem cells in dense collagen gel. TEBVs were mechanically strong enough to allow endothelialization and perfusion at physiological shear stresses within 3 hours after fabrication. After 1 week of perfusion, TEBVs exhibited endothelial release of nitric oxide, phenylephrine-induced vasoconstriction, and acetylcholine-induced vasodilation, all of which were maintained up to 5 weeks in culture. Vasodilation was blocked with the addition of the nitric oxide synthase inhibitor L-N(G)-Nitroarginine methyl ester (L-NAME). TEBVs elicited reversible activation to acute inflammatory stimulation by TNF-α which had a transient effect upon acetylcholine-induced relaxation, and exhibited dose-dependent vasodilation in response to caffeine and theophylline. Treatment of TEBVs with 1 µM lovastatin for three days prior to addition of Tumor necrosis factor - α (TNF-α) blocked the injury response and maintained vasodilation. These results indicate the potential to develop a rapidly-producible, endothelialized TEBV for microphysiological systems capable of producing physiological responses to both pharmaceutical and immunological stimuli.

Multi-ion ionic liquids and a direct, reproducible, diversity-oriented way to make them.

Multi-ion ionic liquids featuring large numbers of distinct imidazolium cations can be easily and reproducibly prepared in a simple one-pot procedure. The method provides a dramatic improvement in efficiency over the almost universally used approach of mixing pre-existing ILs to make multi-ion systems.

Patient-derived endothelial progenitor cells improve vascular graft patency in a rodent model.

Late outgrowth endothelial progenitor cells (EPCs) derived from the peripheral blood of patients with significant coronary artery disease were sodded into the lumens of small diameter expanded polytetrafluoroethylene (ePTFE) vascular grafts. Grafts (1mm inner diameter) were denucleated and sodded either with native EPCs or with EPCs transfected with an adenoviral vector containing the gene for human thrombomodulin (EPC+AdTM). EPC+AdTM was shown to increase the in vitro rate of graft activated protein C (APC) production 4-fold over grafts sodded with untransfected EPCs (p<0.05). Unsodded control and EPC-sodded and EPC+AdTM-sodded grafts were implanted bilaterally into the femoral arteries of athymic rats for 7 or 28 days. Unsodded control grafts, both with and without denucleation treatment, each exhibited 7 day patency rates of 25%. Unsodded grafts showed extensive thrombosis and were not tested for patency over 28 days. In contrast, grafts sodded with untransfected EPCs or EPC+AdTM both had 7 day patency rates of 88-89% and 28 day patency rates of 75-88%. Intimal hyperplasia was observed near both the proximal and distal anastomoses in all sodded graft conditions but did not appear to be the primary occlusive failure event. This in vivo study suggests autologous EPCs derived from the peripheral blood of patients with coronary artery disease may improve the performance of synthetic vascular grafts, although no differences were observed between untransfected EPCs and TM transfected EPCs.

A Multiplex PCR assay to differentiate between dog and red fox.

Foxes are frequently the cause of car accidents in Baden-Württemberg (BW, Germany). The domestic dog (Canis familiaris) is in close relation to the red fox (Vulpes vulpes) and the silver fox which is a coat colour variant of the red fox. As insurance claims that involve accidents with animals require authentication, we analyzed frequency distribution and allele sizes in two canine microsatellite loci in 26 dogs (different breeds) and 19 red foxes of the region of BW, Germany. Moreover, sequencing analysis was performed. Red foxes exhibited only 1 allele at each microsatellite locus, whereas in dog 7 alleles at the CPH4 locus and 6 alleles at the CPH12 locus were detected. Sequences of PCR products from the two species revealed several differences between dogs and foxes. We established a sequenced allelic ladder and give population data from dogs and red foxes from the region of BW, Germany. Using microsatellite polymorphisms is efficient in differentiating between dogs and foxes in forensic casework.

[Nephropathia epidemica caused by Puumala hantavirus infection: a case report from the outpatient sector]. / Nephropathia epidemica durch Hantavirus-Infektion vom Puumala-Typ: Ein Fallbericht aus dem ambulanten Sektor.

HISTORY AND ADMISSION FINDINGS: A 42-year-old man without pre-existing health problems presented to his family practitioner in Baden-Württemberg with fever (up to 39˚ C for two days), headache, abdominal pain, back pain and aching limbs. Ten days before, he had done heavy gardening work. He felt diffuse pain on abdominal palpation. The physical examination of the skin, lymph nodes, the heart, the lungs and the oral mucosa was unremarkable. INVESTIGATIONS AND DIAGNOSIS: Erythrocytes, leukocytes and sporadic bacteria were found in the urine. Urine test strip analysis gave a threefold positive result for protein. The blood test revealed in an elevated C-reactive protein, leukocytosis, elevated creatinine and thrombocytopenia. Enlarged kidneys and an enlarged spleen were found on ultra sound examination. IgG and IgM tested for Hantavirus infection were detected by IFA (Immunofluorescence antibody assay) and by ELISA (enzyme-linked immunosorbent assay). TREATMENT AND COURSE: The blood tests had returned to normal by 15 days after onset of the fever which had persisted for 7 days. Oliguria and/or anuria did not occur. After three weeks of illness, the blood pressure was found to be at hypertensive levels and the patient was treated with antihypertensive drugs. CONCLUSION: A history of gardening work (exposure to rodents) and nonspecific symptoms (like headache and fever), in combination with elevated serum creatinine and thrombocytopenia, should raise the suspicion of nephropathia epidemica (hemorrhagic fever with renal syndrome) caused by hantavirus infection. As sequelae of hantavirus infection may persist, patients should subsequently be followed for clinical and laboratory evidence of renal disease. Hospitalization is not generally warranted.

3-(1-Methyl-3-imidazolio)propane-sulfonate: a precursor to a Brønsted acid ionic liquid.

The title compound, C(7)H(12)N(2)O(3)S, is a zwitterion precursor to a Brønsted acid ionic liquid with potential as an acid catalyst. The C-N-C-C torsion angle of 100.05 (8)° allows the positively charged imidazolium head group and the negatively charged sulfonate group to inter-act with neighboring zwitterions, forming a C-H⋯O hydrogen-bonding network; the shortest among these inter-actions is 2.9512 (9) Å. The C-H⋯O inter-actions can be described by graph-set notation as two R(2) (2)(16) and one R(2) (2)(5) hydrogen-bonded rings.

Intravital microscopy evaluation of angiogenesis and its effects on glucose sensor performance.

An optical window model for the rodent dorsum was used to perform chronic and quantitative intravital microscopy and laser Doppler flowmetry of microvascular networks adjacent to functional and non-functional glucose sensors. The one-sided configuration afforded direct, real-time observation of the tissue response to bare (unmodified, smooth surface) sensors and sensors coated with porous poly-L-lactic acid (PLLA). Microvessel length density and red blood cell flux (blood perfusion) within 1 mm of the sensors were measured bi-weekly over 2 weeks. When non-functional sensors were fully implanted beneath the windows, the porous coated sensors had two-fold more vasculature and significantly higher blood perfusion than bare sensors on Day 14. When functional sensors were implanted percutaneously, as in clinical use, no differences in baseline current, neovascularization, or tissue perfusion were observed between bare and porous coated sensors. However, percutaneously implanted bare sensors had two-fold more vascularity than fully implanted bare sensors by Day 14, indicating the other factors, such as micromotion, might be stimulating angiogenesis. Despite increased angiogenesis adjacent to percutaneous sensors, modest sensor current attenuation occurred over 14 days, suggesting that factors other than angiogenesis may play a dominant role in determining sensor function.

Cytokine profiling using monocytes/macrophages cultured on common biomaterials with a range of surface chemistries.

Cytokines, chemokines, and growth factors were assayed from the supernatants of monocytes and macrophages cultured on common biomaterials with a range of surface chemistries. TNF-alpha, MCP-1, MIP-1alpha, IL-8, IL-6, IL-1beta, VEGF, IL-1ra, and IL-10 were measured from monocyte/macrophage cultures at different stages of activation and differentiation seeded onto polyethylene, polyurethane, expanded polytetrafluoroethylene, polymethyl methacrylate, and a hydrogel copolymer of 2-hydroxyethyl methacrylate, 1-vinyl-2-pyrrolidinone, and polyethylene glycol acrylate in tissue culture polystyrene (TCPS) plates. Empty TCPS wells and organo-tin polyvinyl chloride served as "blanks" and positive controls, respectively. Results showed an overall increase in cytokine, chemokine, and growth factor production as monocytes are activated or differentiated into macrophages and that proinflammatory and anti-wound healing cytokines and chemokines dominate this profile. However, cytokine production was only modestly affected by the surface chemistry of these four stable and noncytotoxic biomaterials.

Instructional PowerPoint presentations for cutaneous wound healing and tissue response to sutures.

Wound healing is an intricate process involving the interaction of cells and molecules, resulting in a complex series of events that change the morphology and characteristics of the wounded area. Interactive animations are useful for illustrating challenging concepts, helping students learn and retain new material. Instructional PowerPoint presentations describing the basic elements of cutaneous wound healing and the response of cutaneous tissue to sutures were developed by seven biomedical engineering students at Duke University. "Cutaneous Wound Healing.ppt" is an interactive presentation reviewing the four phases of wound healing (hemostasis, inflammation, repair, and remodeling) as well as the major molecular and cellular mechanisms that comprise these processes for cutaneous tissue. "Tissue Response to Sutures.ppt" is an interactive presentation that uses sutures to illustrate the foreign body response to biomaterials in cutaneous tissue. The tissue response program reviews the basics of suturing, common suture materials, and the tissue, cellular, and molecular responses to absorbable and nonabsorbable sutures. This manuscript provides a brief overview of the programs that are freely available on the Duke Center for Biomolecular and Tissue Engineering web site at http://bte.egr.duke.edu.

In vitro and in vivo characterization of porous poly-L-lactic acid coatings for subcutaneously implanted glucose sensors.

The purpose of this study was to test the hypothesis that porous poly-L-lactic acid (PLLA) sensor coatings reduce fibrosis and promote blood microvessel formation in tissue adjacent to the sensor surface. Porous PLLA coatings were produced using ammonium bicarbonate as the gas foaming/salt leaching agent, and deployed on functional and nonfunctional sensors. The porous coatings minimally affected sensor accuracy and response rate in vitro. Three-week subcutaneous rat studies of nonfunctional glucose sensors showed the anticipated effect of porous coatings enhancing vascularity and decreasing collagen deposition. In contrast, percutaneous functional sensors with and without porous coatings showed no significant difference in terms of histology or sensor response. In spite of the observation that texturing increases the vascularity of the tissue that surrounds implanted sensors, other factors such as the additional mechanical stresses imposed by percutaneous tethering may override the beneficial effects of the porous coatings.

Percutaneous window chamber method for chronic intravital microscopy of sensor-tissue interactions.

BACKGROUND: A dorsal, two-sided skin-fold window chamber model was employed previously by Gough in glucose sensor research to characterize poorly understood physiological factors affecting sensor performance. We have extended this work by developing a percutaneous one-sided window chamber model for the rodent dorsum that offers both a larger subcutaneous area and a less restrictive tissue space than previous animal models. METHOD: A surgical procedure for implanting a sensor into the subcutis beneath an acrylic window (15 mm diameter) is presented. Methods to quantify changes in the microvascular network and red blood cell perfusion around the sensors using noninvasive intravital microscopy and laser Doppler flowmetry are described. The feasibility of combining interstitial glucose monitoring from an implanted sensor with intravital fluorescence microscopy was explored using a bolus injection of fluorescein and dextrose to observe real-time mass transport of a small molecule at the sensor-tissue interface. RESULTS: The percutaneous window chamber provides an excellent model for assessing the influence of different sensor modifications, such as surface morphologies, on neovascularization using real-time monitoring of the microvascular network and tissue perfusion. However, the tissue response to an implanted sensor was variable, and some sensors migrated entirely out of the field of view and could not be observed adequately. CONCLUSIONS: A percutaneous optical window provides direct, real-time images of the development and dynamics of microvascular networks, microvessel patency, and fibrotic encapsulation at the tissue-sensor interface. Additionally, observing microvessels following combined bolus injections of a fluorescent dye and glucose in the local sensor environment demonstrated a valuable technique to visualize mass transport at the sensor surface.

The Achilles tendon as a DNA source for STR typing of highly decayed corpses.

Forensic criminal casework often involves DNA profiling of human postmortem tissues, whereas degradational processes can affect PCR-based Short Tandem Repeat (STR) analysis. Degradation of DNA is observed to vary among different tissues and with time. Therefore, the stability of DNA in Achilles tendon samples is compared to that in muscle and kidney specimens with a variety of postmortem histories. Tissue samples from 28 autopsy cases, including 15 decomposed corpses and a control group of 13 nondecayed corpses were analysed. DNA was isolated using the All-tissue DNA Kit (GEN-IAL, Troisdorf, Germany), quantified by spectrophotometric measurement, amplified by the multiplex PCR genRES MPX-2 (Serac, Bad Homburg, Germany), and analysed on the ABI PRISM 310 Genetic Analyzer (Applied Biosystems, Darmstadt, Germany). Quantitative analysis of nondecomposed tissues revealed that the recovery of DNA was highest in kidney followed by muscle, whereas Achilles tendon tissue was the poorest source of isolated DNA. Only small amounts of DNA were present in both kidney and muscle samples from decomposed corpses. However, from decayed Achilles tendon samples twice as much DNA as from nondecayed samples could be isolated on average. These results suggest DNA to be better protected in Achilles tendons. Moreover, postmortem changes in Achilles tendons may even improve DNA isolation.

Vascular endothelial growth factor and dexamethasone release from nonfouling sensor coatings affect the foreign body response.

Vascular endothelial growth factor (VEGF) and dexamethasone (DX) release from hydrogel coatings were examined as a means to modify tissue inflammation and induce angiogenesis. Antibiofouling hydrogels for implantable glucose sensor coatings were prepared from 2-hydroxyethyl methacrylate, N-vinyl pyrrolidinone, and polyethylene glycol. Microdialysis sampling was used to test the effect of the hydrogel coating on glucose recovery. VEGF-releasing hydrogel-coated fibers increased vascularity and inflammation in the surrounding tissue after 2 weeks of implantation compared to hydrogel-coated fibers. DX-releasing hydrogel-coated fibers reduced inflammation compared to hydrogel-coated fibers and had reduced capsule vascularity compared to VEGF-releasing hydrogel-coated fibers. Hydrogels that released both VEGF and DX simultaneously also showed reduced inflammation at 2 weeks implantation; however, no enhanced vessel formation was observed indicating that the DX diminished the VEGF effect. At 6 weeks, there were no detectable differences between drug-releasing hydrogel-coated fibers and control fibers. From this study, hydrogel drug release affected initial events of the foreign body response with DX inhibiting VEGF, but once the drug depot was exhausted these effects disappeared.

Glucose recovery with bare and hydrogel-coated microdialysis probes: experiment and simulation of temporal effects.

In vitro microdialysis glucose sampling was used to test the transient and steady-state suitability of antifouling hydrogel coatings, composed of 2-hydroxyethyl methacrylate, vinylpyrrolidinone, and poly(ethylene glycol). The in vitro glucose diffusion coefficients of bare microdialysis membranes and hydrogel coatings were determined experimentally to be 1.1 x 10-6 and 3.2 x 10-6 cm2/s, respectively. These values were used to numerically simulate the effect of the hydrogel on glucose transport across the microdialysis membrane using a convection-diffusion transport model. The times for dialysate at the exit of the bare and hydrogel-coated microdialysis probes to reach 95% of steady state were calculated to be 20 and 66 s, respectively. However, the experimental data showed that 95% of steady-state glucose recoveries were reached after 4-5 min. Numerical simulations incorporating the Taylor dispersion in the outlet tubing showed the time difference was caused almost completely by convective transport in the outlet tubing with negligible contribution from analyte profile broadening. These data indicated that the hydrogel coatings imposed 44% reduction in glucose permeability and consequently 26% reduction in the percent recovery. The effect of hydrogel coatings on the time to reach the steady-state recovery was insignificant compared with the time required for convection of glucose in the outlet tubing.

In vitro model of glial scarring around neuroelectrodes chronically implanted in the CNS.

A novel in vitro model of glial scarring was developed by adapting a primary cell-based system previously used for studying neuroinflammatory processes in neurodegenerative disease. Midbrains from embryonic day 14 Fischer 344 rats were mechanically dissociated and grown on poly-D-lysine coated 24 well plates to a confluent layer of neurons, astrocytes, and microglia. The culture was injured with either a mechanical scrape or foreign-body placement (segments of 50 microm diameter stainless steel microwire), fixed at time points from 6 h to 10 days, and assessed by immunocytochemistry. Microglia invaded the scraped wound area at early time points and hypertrophied activated astrocytes repopulated the wound after 7 days. The chronic presence of microwire resulted in a glial scar forming at 10 days, with microglia forming an inner layer of cells coating the microwire, while astrocytes surrounded the microglial core with a network of cellular processes containing upregulated GFAP. Vimentin expressing cells and processes were present in the scrape at early times and within the astrocyte processes forming the glial scar. Neurons within the culture did not repopulate the scrape wound and did not respond to the microwire, although they were determined to be electrically active through patch clamp recording. The time course and relative positions of the glia in response to the different injury paradigms correlated well with stereotypical in vivo responses and warrant further work in the development of a functional in vitro test bed.

Combustible ionic liquids by design: is laboratory safety another ionic liquid myth?

The non-flammability of ionic liquids (ILs) is often highlighted as a safety advantage of ILs over volatile organic compounds (VOCs), but the fact that many ILs are not flammable themselves does not mean that they are safe to use near fire and/or heat sources; a large group of ILs (including commercially available ILs) are combustible due to the nature of their positive heats of formation, oxygen content, and decomposition products.