Mitochondrial sulfide promotes life span and health span through distinct mechanisms in developing versus adult treated Caenorhabditis elegans.

Living longer without simultaneously extending years spent in good health ("health span") is an increasing societal burden, demanding new therapeutic strategies. Hydrogen sulfide (H2S) can correct disease-related mitochondrial metabolic deficiencies, and supraphysiological H2S concentrations can pro health span. However, the efficacy and mechanisms of mitochondrion-targeted sulfide delivery molecules (mtH2S) administered across the adult life course are unknown. Using a Caenorhabditis elegans aging model, we compared untargeted H2S (NaGYY4137, 100 µM and 100 nM) and mtH2S (AP39, 100 nM) donor effects on life span, neuromuscular health span, and mitochondrial integrity. H2S donors were administered from birth or in young/middle-aged animals (day 0, 2, or 4 postadulthood). RNAi pharmacogenetic interventions and transcriptomics/network analysis explored molecular events governing mtH2S donor-mediated health span. Developmentally administered mtH2S (100 nM) improved life/health span vs. equivalent untargeted H2S doses. mtH2S preserved aging mitochondrial structure, content (citrate synthase activity) and neuromuscular strength. Knockdown of H2S metabolism enzymes and FoxO/daf-16 prevented the positive health span effects of mtH2S, whereas DCAF11/wdr-23 - Nrf2/skn-1 oxidative stress protection pathways were dispensable. Health span, but not life span, increased with all adult-onset mtH2S treatments. Adult mtH2S treatment also rejuvenated aging transcriptomes by minimizing expression declines of mitochondria and cytoskeletal components, and peroxisome metabolism hub components, under mechanistic control by the elt-6/elt-3 transcription factor circuit. H2S health span extension likely acts at the mitochondrial level, the mechanisms of which dissociate from life span across adult vs. developmental treatment timings. The small mtH2S doses required for health span extension, combined with efficacy in adult animals, suggest mtH2S is a potential healthy aging therapeutic.

Capillary imbibition of confined monodisperse emulsions in microfluidic channels.

We study imbibition of a monodisperse emulsion into high-aspect ratio microfluidic channels with the height h comparable to the droplet diameter d. Two distinct regimes are identified in the imbibition dynamics. In a strongly confined system (the confinement ratio d/h = 1.2 in our experiments), the droplets are flattened between the channel walls and move more slowly compared to the average suspension velocity. As a result, a droplet-free region forms behind the meniscus (separated from the suspension region by a sharp concentration front) and the suspension exhibits strong droplet-density and velocity fluctuations. In a weaker confinement, d/h = 0.65, approximately spherical droplets move faster than the average suspension flow, causing development of a dynamically unstable high-concentration region near the meniscus. This instability results in the formation of dense droplet clusters, which migrate downstream relative to the average suspension flow, thus affecting the entire suspension dynamics. We explain the observed phenomena using linear transport equations for the particle-phase and suspension fluxes driven by the local pressure gradient. We also use a dipolar particle interaction model to numerically simulate the imbibition dynamics. The observed large velocity fluctuations in strongly confined systems are elucidated in terms of migration of self-assembled particle chains with highly anisotropic mobility.

Mitochondrial hydrogen sulfide supplementation improves health in the C. elegans Duchenne muscular dystrophy model.

Duchenne muscular dystrophy (DMD) is an X-linked recessive disorder characterized by progressive muscle degeneration and weakness due to mutations in the dystrophin gene. The symptoms of DMD share similarities with those of accelerated aging. Recently, hydrogen sulfide (H2S) supplementation has been suggested to modulate the effects of age-related decline in muscle function, and metabolic H2S deficiencies have been implicated in affecting muscle mass in conditions such as phenylketonuria. We therefore evaluated the use of sodium GYY4137 (NaGYY), a H2S-releasing molecule, as a possible approach for DMD treatment. Using the dys-1(eg33) Caenorhabditis elegans DMD model, we found that NaGYY treatment (100 µM) improved movement, strength, gait, and muscle mitochondrial structure, similar to the gold-standard therapeutic treatment, prednisone (370 µM). The health improvements of either treatment required the action of the kinase JNK-1, the transcription factor SKN-1, and the NAD-dependent deacetylase SIR-2.1. The transcription factor DAF-16 was required for the health benefits of NaGYY treatment, but not prednisone treatment. AP39 (100 pM), a mitochondria-targeted H2S compound, also improved movement and strength in the dys-1(eg33) model, further implying that these improvements are mitochondria-based. Additionally, we found a decline in total sulfide and H2S-producing enzymes in dystrophin/utrophin knockout mice. Overall, our results suggest that H2S deficit may contribute to DMD pathology, and rectifying/overcoming the deficit with H2S delivery compounds has potential as a therapeutic approach to DMD treatment.

Microfluidic tapered aspirators for mechanical characterization of microgel beads.

In this study, we report a microfluidic approach for the measurement of mechanical properties of spherical microgel beads. This technique is analogous to tapered micropipette aspiration, while harnessing the benefits of microfluidics. We fabricate alginate-based microbeads and determine their mechanical properties using the microfluidic tapered aspirators. Individual microgel beads are aspirated and trapped in tapered channels, the deformed equilibrium shape is measured, and a stress balance is used to determine the Young's modulus. We investigate the effect of surface coating, taper angle, and bead diameter and find that the measured modulus is largely insensitive to these parameters. We show that the bead modulus increases with alginate concentration and follows a trend similar to that of the modulus measured using standard uniaxial compression. The critical pressure to squeeze out the beads from the tapered aspirators was found to depend on both the modulus and the bead diameter. Finally, we demonstrate how temporal changes in bead moduli due to enzymatic degradation of the hydrogel could be quantitatively determined. The results from this study highlight that the microfluidic tapered aspirators are a useful tool to measure hydrogel bead mechanics and have the potential to characterize dynamic changes in mechanical properties.

Swim exercise in Caenorhabditis elegans extends neuromuscular and gut healthspan, enhances learning ability, and protects against neurodegeneration.

Regular physical exercise is the most efficient and accessible intervention known to promote healthy aging in humans. The molecular and cellular mechanisms that mediate system-wide exercise benefits, however, remain poorly understood, especially as applies to tissues that do not participate directly in training activity. The establishment of exercise protocols for short-lived genetic models will be critical for deciphering fundamental mechanisms of transtissue exercise benefits to healthy aging. Here we document optimization of a long-term swim exercise protocol for Caenorhabditis elegans and we demonstrate its benefits to diverse aging tissues, even if exercise occurs only during a restricted phase of adulthood. We found that multiple daily swim sessions are essential for exercise adaptation, leading to body wall muscle improvements in structural gene expression, locomotory performance, and mitochondrial morphology. Swim exercise training enhances whole-animal health parameters, such as mitochondrial respiration and midlife survival, increases functional healthspan of the pharynx and intestine, and enhances nervous system health by increasing learning ability and protecting against neurodegeneration in models of tauopathy, Alzheimer's disease, and Huntington's disease. Remarkably, swim training only during early adulthood induces long-lasting systemic benefits that in several cases are still detectable well into midlife. Our data reveal the broad impact of swim exercise in promoting extended healthspan of multiple C. elegans tissues, underscore the potency of early exercise experience to influence long-term health, and establish the foundation for exploiting the powerful advantages of this genetic model for the dissection of the exercise-dependent molecular circuitry that confers system-wide health benefits to aging adults.

Roll maneuvers are essential for active reorientation of Caenorhabditis elegans in 3D media.

Locomotion of the nematode Caenorhabditis elegans is a key observable used in investigations ranging from behavior to neuroscience to aging. However, while the natural environment of this model organism is 3D, quantitative investigations of its locomotion have been mostly limited to 2D motion. Here, we present a quantitative analysis of how the nematode reorients itself in 3D media. We identify a unique behavioral state of C. elegans-a roll maneuver-which is an essential component of 3D locomotion in burrowing and swimming. The rolls, associated with nonzero torsion of the nematode body, result in rotation of the plane of dorsoventral body undulations about the symmetry axis of the trajectory. When combined with planar turns in a new undulation plane, the rolls allow the nematode to reorient its body in any direction, thus enabling complete exploration of 3D space. The rolls observed in swimming are much faster than the ones in burrowing; we show that this difference stems from a purely hydrodynamic enhancement mechanism and not from a gait change or an increase in the body torsion. This result demonstrates that hydrodynamic viscous forces can enhance 3D reorientation in undulatory locomotion, in contrast to known hydrodynamic hindrance of both forward motion and planar turns.

Catastrophic thermal destabilization of two-dimensional close-packed emulsions due to synchronous coalescence initiation.

The mechanisms for phase separation in highly concentrated emulsions when subjected to a thermal phase transition remain to be elucidated. Here, we create a hexagonally close-packed monodisperse emulsion in 2D and show that during a cool-heat cycle, the emulsion fully destabilizes akin to phase separation. The mechanism for this catastrophic destabilization is found to be spontaneous coalescence initiation that synchronously occurs between every solidified droplet and its neighbors. This synchronous coalescence initiation establishes system-wide network connectivity in the emulsion causing large-scale destabilization. This system-wide coalescence initiation is found to be insensitive to droplet size and tested surfactants, but dependent on network connectivity and crystal content of individual droplets.

Hemodialysis-related headache and how to prevent it.

BACKGROUND AND PURPOSE: Hemodialysis (HD) may have some adverse effects on the nervous system. Headache is the most commonly reported neurological symptom amongst HD patients. Our aim was to determine the frequency, clinical characteristics and triggering factors of HD-related headache (HRH) and to evaluate preventive strategies for reducing HRH. METHOD: In all, 494 patients were included. Comparative controls (CC) were classified within the same patients without headache. Arterial systolic/diastolic blood pressure, blood urea nitrogen (BUN) and creatinine were correlated before/after one HD. The urea reduction ratio during the dialysis session was determined. RESULTS: A total of 175 patients (35.4%) with a mean age of 57.3 ± 15.7 years were diagnosed with HRH. HRH was more common in males (P < 0.001). Headache was started a mean of 2.90 ± 0.86 h after the HD. The common localization of pain was reported to be bifrontal in 41.7% (n = 73). The mean duration of headache was 6.22 ± 7.8 h, with a duration of ≤4 h reported by 64.0% of patients. The mean Visual Analog Scale score was 5.64 ± 2.05. The differences between pre/post-dialysis BUN values were 94.6 ± 31.1 in HRH patients and 86.8 ± 28.5 in the CC group (P = 0.006). The systolic blood pressure difference between the pre/post-dialysis measurements was 22.4 ± 16.5 mmHg in HRH patients and 12.8 ± 19.4 mmHg in CC(P < 0.001). Patients with HRH had significantly higher mean systolic and diastolic blood pressure pre-dialysis values (systolic, P = 0.002; diastolic, P < 0.001). The differences in systolic/diastolic blood pressure between pre/post-dialysis were higher in the HRH group (P < 0.001, P = 0.001, respectively). CONCLUSION: Regulating the frequency and timing of dialysis may provide better management in HRH with high BUN levels and high pre-dialysis blood pressure.

ECTRIMS/EAN guideline on the pharmacological treatment of people with multiple sclerosis.

BACKGROUND AND PURPOSE: Multiple sclerosis (MS) is a complex disease of the central nervous system. As new drugs are becoming available, knowledge on diagnosis and treatment must continuously evolve. There is therefore a need for a reference tool compiling current data on benefit and safety, to aid professionals in treatment decisions and use of resources across Europe. The European Committee of Treatment and Research in Multiple Sclerosis (ECTRIMS) and the European Academy of Neurology (EAN) have joined forces to meet this need. The objective was to develop an evidence-based clinical practice guideline for the pharmacological treatment of people with MS to guide healthcare professionals in the decision-making process. METHODS: This guideline has been developed using the GRADE methodology and following the recently updated EAN recommendations for guideline development. Clinical questions were formulated in PICO format (patient, intervention, comparator, outcome) and outcomes were prioritized according to their relevance to clinical practice. An exhaustive literature search up to December 2016 was performed for each question and the evidence is presented narratively and, when possible, combined in a meta-analysis using a random-effects model. The quality of evidence for each outcome was rated into four categories - very high, high, low and very low - according to the risk of bias. GRADE evidence profiles were created using GRADEprofiler (GRADEpro) software (Version 3.6). The recommendations with assigned strength (strong, weak) were formulated based on the quality of evidence and the risk-benefit balance. Consensus between the panellists was reached by use of the modified nominal group technique. RESULTS: A total of 10 questions have been agreed, encompassing treatment efficacy, response criteria, strategies to address suboptimal response and safety concerns and treatment strategies in MS and pregnancy. The guideline takes into account all disease-modifying drugs approved by the European Medicine Agency at the time of publication. A total of 20 recommendations were agreed by the guideline working group members after three rounds of consensus.

Conditional genetic deletion of Ano1 in interstitial cells of Cajal impairs Ca2+ transients and slow waves in adult mouse small intestine.

Myenteric plexus interstitial cells of Cajal (ICC-MY) in the small intestine are Kit+ electrical pacemakers that express the Ano1/TMEM16A Ca2+-activated Cl- channel, whose functions in the gastrointestinal tract remain incompletely understood. In this study, an inducible Cre-LoxP-based approach was used to advance the understanding of Ano1 in ICC-MY of adult mouse small intestine. KitCreERT2/+;Ano1Fl/Fl mice were treated with tamoxifen or vehicle, and small intestines (mucosa free) were examined. Quantitative RT-PCR demonstrated ~50% reduction in Ano1 mRNA in intestines of conditional knockouts (cKOs) compared with vehicle-treated controls. Whole mount immunohistochemistry showed a mosaic/patchy pattern loss of Ano1 protein in ICC networks. Ca2+ transients in ICC-MY network of cKOs displayed reduced duration compared with highly synchronized controls and showed synchronized and desynchronized profiles. When matched, the rank order for Ano1 expression in Ca2+ signal imaged fields of view was as follows: vehicle controls>>>cKO(synchronized)>cKO(desynchronized). Maintenance of Ca2+ transients' synchronicity despite high loss of Ano1 indicates a large functional reserve of Ano1 in the ICC-MY network. Slow waves in cKOs displayed reduced duration and increased inter-slow-wave interval and occurred in regular- and irregular-amplitude oscillating patterns. The latter activity suggested ongoing interaction by independent interacting oscillators. Lack of slow waves and depolarization, previously reported for neonatal constitutive knockouts, were also seen. In summary, Ano1 in adults regulates gastrointestinal function by determining Ca2+ transients and electrical activity depending on the level of Ano1 expression. Partial Ano1 loss results in Ca2+ transients and slow waves displaying reduced duration, while complete and widespread absence of Ano1 in ICC-MY causes lack of slow wave and desynchronized Ca2+ transients.NEW & NOTEWORTHY The Ca2+-activated Cl- channel, Ano1, in interstitial cells of Cajal (ICC) is necessary for normal gastrointestinal motility. We knocked out Ano1 to varying degrees in ICC of adult mice. Partial knockout of Ano1 shortened the widths of electrical slow waves and Ca2+ transients in myenteric ICC but Ca2+ transient synchronicity was preserved. Near-complete knockout was necessary for transient desynchronization and loss of slow waves, indicating a large functional reserve of Ano1 in ICC.

The integrin-adhesome is required to maintain muscle structure, mitochondrial ATP production, and movement forces in Caenorhabditis elegans.

The integrin-adhesome network, which contains >150 proteins, is mechano-transducing and located at discreet positions along the cell-cell and cell-extracellular matrix interface. A small subset of the integrin-adhesome is known to maintain normal muscle morphology. However, the importance of the entire adhesome for muscle structure and function is unknown. We used RNA interference to knock down 113 putative Caenorhabditis elegans homologs constituting most of the mammalian adhesome and 48 proteins known to localize to attachment sites in C. elegans muscle. In both cases, we found >90% of components were required for normal muscle mitochondrial structure and/or proteostasis vs. empty vector controls. Approximately half of these, mainly proteins that physically interact with each other, were also required for normal sarcomere and/or adhesome structure. Next we confirmed that the dystrophy observed in adhesome mutants associates with impaired maximal mitochondrial ATP production (P < 0.01), as well as reduced probability distribution of muscle movement forces compared with wild-type animals. Our results show that the integrin-adhesome network as a whole is required for maintaining both muscle structure and function and extend the current understanding of the full complexities of the functional adhesome in vivo.

Collective dynamics of non-coalescing and coalescing droplets in microfluidic parking networks.

We study the complex collective dynamics mediated by flow resistance interactions when trains of non-coalescing and coalescing confined drops are introduced into a microfluidic parking network (MPN). The MPN consists of serially connected loops capable of parking arrays of drops. We define parking modes based on whether drops park without breakage or drop fragments are parked subsequent to breakage or drops park after coalescence. With both non-coalescing and coalescing drops, we map the occurrence of these parking modes in MPNs as a function of system parameters including drop volume, drop spacing and capillary number. We find that the non-coalescing drops can either park or break in the network, producing highly polydisperse arrays. We further show that parking due to collision induced droplet break-up is the main cause of polydispersity. We discover that collisions occur due to a crowding instability, which is a natural outcome of the network topology. In striking contrast, with coalescing drops we show that the ability of drops to coalesce rectifies the volume of parked polydisperse drops, despite drops breaking in the network. We find that several parking modes act in concert during this hydrodynamic self-rectification mechanism, producing highly monodisperse drop arrays over a wide operating parameter space. We demonstrate that the rectification mechanism can be harnessed to produce two-dimensional arrays of microfluidic drops with highly tunable surface-to-volume ratios, paving the way for fundamental investigations of interfacial phenomena in emulsions.

European Headache Federation consensus on technical investigation for primary headache disorders.

The diagnosis of primary headache disorders is clinical and based on the diagnostic criteria of the International Headache Society (ICHD-3-beta). However several brain conditions may mimic primary headache disorders and laboratory investigation may be needed. This necessity occurs when the treating physician doubts for the primary origin of headache. Features that represent a warning for a possible underlying disorder causing the headache are new onset headache, change in previously stable headache pattern, headache that abruptly reaches the peak level, headache that changes with posture, headache awakening the patient, or precipitated by physical activity or Valsalva manoeuvre, first onset of headache ≥50 years of age, neurological symptoms or signs, trauma, fever, seizures, history of malignancy, history of HIV or active infections, and prior history of stroke or intracranial bleeding. All national headache societies and the European Headache Alliance invited to review and comment the consensus before the final draft. The consensus recommends brain MRI for the case of migraine with aura that persists on one side or in brainstem aura. Persistent aura without infarction and migrainous infarction require brain MRI, MRA and MRV. Brain MRI with detailed study of the pituitary area and cavernous sinus, is recommended for all TACs. For primary cough headache, exercise headache, headache associated with sexual activity, thunderclap headache and hypnic headache apart from brain MRI additional tests may be required. Because there is little and no good evidence the committee constructed a consensus based on the opinion of experts, and should be treated as imperfect.

Characterization of neuromyelitis optica and neuromyelitis optica spectrum disorder patients with a late onset.

BACKGROUND: Few data are available for patients with a late onset (≥ 50 years) of neuromyelitis optica (LONMO) or neuromyelitis optica spectrum disease (LONMOSD), defined by an optic neuritis/longitudinally extensive transverse myelitis with aquaporin-4 antibodies (AQP4-Ab). OBJECTIVE: To characterize LONMO and LONMOSD, and to analyze their predictive factors of disability and death. METHODS: We identified 430 patients from four cohorts of NMO/NMOSD in France, Germany, Turkey and UK. We extracted the late onset patients and analyzed them for predictive factors of disability and death, using the Cox proportional model. RESULTS: We followed up on 63 patients with LONMO and 45 with LONMOSD during a mean of 4.6 years. This LONMO/LONMOSD cohort was mainly of Caucasian origin (93%), women (80%), seropositive for AQP4-Ab (85%) and from 50 to 82.5 years of age at onset. No progressive course was noted. At last follow-up, the median Expanded Disability Status Scale (EDSS) scores were 5.5 and 6 in the LONMO and LONMOSD groups, respectively. Outcome was mainly characterized by motor disability and relatively good visual function. At last follow-up, 14 patients had died, including seven (50%) due to acute myelitis and six (43%) because of opportunistic infections. The EDSS 4 score was independently predicted by an older age at onset, as a continuous variable after 50 years of age. Death was predicted by two independent factors: an older age at onset and a high annualized relapse rate. CONCLUSION: LONMO/LONMOSD is particularly severe, with a high rate of motor impairment and death.

FHOD-1 and profilin protect sarcomeres against contraction-induced deformation> in C. elegans.

Formin HOmology Domain 2-containing (FHOD) proteins are a subfamily of actin-organizing formins important for striated muscle development in many animals. We showed previously that absence of the sole FHOD protein, FHOD-1, from Caenorhabditis elegans results in thin body wall muscles with misshapen dense bodies that serve as sarcomere Z-lines. We demonstrate here that mutations predicted to specifically disrupt actin polymerization by FHOD-1 similarly disrupt muscle development, and that FHOD-1 cooperates with profilin PFN-3 for dense body morphogenesis, and with profilins PFN-2 and PFN-3 to promote body wall muscle growth. We further demonstrate that dense bodies in worms lacking FHOD-1 or PFN-2/PFN-3 are less stable than in wild-type animals, having a higher proportion of dynamic protein, and becoming distorted by prolonged muscle contraction. We also observe accumulation of actin and actin depolymerization factor/cofilin homologue UNC-60B in body wall muscle of these mutants. Such accumulations may indicate targeted disassembly of thin filaments dislodged from unstable dense bodies, possibly accounting for the abnormally slow growth and reduced body wall muscle strength in fhod-1 mutants. Overall, these results implicate FHOD protein-mediated actin assembly in forming stable sarcomere Z-lines, and identify profilin as a new contributor to FHOD activity in striated muscle development.

FHOD-1/profilin-mediated actin assembly protects sarcomeres against contraction-induced deformation in C. elegans.

Formin HOmology Domain 2-containing (FHOD) proteins are a subfamily of actin-organizing formins important for striated muscle development in many animals. We showed previously that absence of the sole FHOD protein, FHOD-1, from C. elegans results in thin body-wall muscles with misshapen dense bodies that serve as sarcomere Z-lines. We demonstrate here that actin polymerization by FHOD-1 is required for its function in muscle development, and that FHOD-1 cooperates with profilin PFN-3 for dense body morphogenesis, and profilins PFN-2 and PFN-3 to promote body-wall muscle growth. We further demonstrate dense bodies in fhod-1 and pfn-3 mutants are less stable than in wild type animals, having a higher proportion of dynamic protein, and becoming distorted by prolonged muscle contraction. We also observe accumulation of actin depolymerization factor/cofilin homolog UNC-60B in body-wall muscle of these mutants. Such accumulations may indicate targeted disassembly of thin filaments dislodged from unstable dense bodies, and may account for the abnormally slow growth and reduced strength of body-wall muscle in fhod-1 mutants. Overall, these results show the importance of FHOD protein-mediated actin assembly to forming stable sarcomere Z-lines, and identify profilin as a new contributor to FHOD activity in striated muscle development.

A multicenter multinational study to evaluate different aspects of the relationship between MS and pregnancy.

BACKGROUND: To investigate the pregnancy-related issues in females with multiple sclerosis (MS) from Turkiye, Egypt, Kuwait, and Iran. METHODS: 1692 pregnancies of 701 females with MS were evaluated in this retrospective multicenter, international project. Demographics, clinical features, pregnancy outcomes, relapses, effects of exposure to disease-modifying drugs on pregnancy and fetus, and worries about pregnancy decisions were investigated. RESULTS: 85.9 % of females were diagnosed with relapsing-remitting multiple sclerosis. The mean age was 39.0 ± 9.0 years (min 20, max 68). The mean EDSS score was 2.26 ± 1.8. The number of conceptions was inversely correlated with the level of education with significance (p<0.05). Among the concerns related to pregnancy, 31.7 % pertain to disability progression, 14.4 % are associated with relapses, and 7.3 % involve the cessation of treatment. Additionally, 82.3 % of females with MS experienced no relapses during both pregnancy and the postpartum period. Most of the relapses (22.9 %) occurred in the postpartum period. Higher EDSS scores were detected in patients who have higher numbers of pre-MS period pregnancies (p= 0.042; r:0.2591). A similar correlation was found between the total number of pregnancies and higher EDSS levels (p=0.003, r:0.2614). Considering the relationship between EDSS score and the number of pregnancies after MS diagnosis, no significance was found (p = 0.595). The age at first pregnancy did not affect the onset age of MS. Significant positive correlation was found between the age of onset and the total number of pregnancies and pre-MS pregnancies. As the number of pregnancies increased, the disease onset was at a later age (correlation = 0.4258). CONCLUSION: Presence of pre-MS pregnancies increased the age of onset of MS and caused more disability. The reduction in the number of pregnancies following the diagnosis of MS was related with a consistent hesitancy among patients in this regard.

Generation of chemical concentration gradients in mobile droplet arrays via fragmentation of long immiscible diluting plugs.

We report a one-step passive microfluidic technique to generate arrays of moving droplets containing variation of chemical concentration between individual drops. We find that a concentration gradient can be established in a long diluting plug by on-chip dilution and extraction of samples via orthogonal coalescence of the plug with a static array of sample drops. The diluting plug containing the gradient is subsequently fragmented by a droplet generator. We show that the technique is flexible, as the dilution range can be tuned by a variety of control parameters including the carrier fluid flow rate, volume of diluting plugs, and stationary drops. We also find that the concentration gradients have a fine resolution and are reproducible to within 2% relative standard deviation. As one demonstrative application, we show the suitability of the technique for generating a dose-response curve for an enzyme inhibition assay. Because of the ability to inject multiple plugs, our technique has the potential for unlimited as well as sequential dilution of a series of substrates. Thus, our method could be valuable as a high-throughput and high-resolution screening tool for assays that require interrogation of the response of one or more target species to numerous distinct chemical concentrations.

Microfluidic production of spherical and nonspherical fat particles by thermal quenching of crystallizable oils.

We report the microfluidic production of spherical and nonspherical fat particles from crystallizable oils. The method is based on microfluidic generation of oil droplets at a cross-junction followed by thermal solidification downstream in a microcapillary. We vary the drop production conditions and the device temperature and demonstrate that the size, shape, and crystallinity can be controlled. By measuring thermal gradients in the microcapillary, we show that crystalline fat particles are best produced when the device temperature is below the onset temperature of bulk fat crystallization. To produce monodisperse nonspherical fat particles, we find that the carrier fluid flow rate needs to be sufficiently high to provide strong hydrodynamic forces to transport the confined rod-like particles. We identify the scaling relationship between geometric confinement and particle elasticity necessary to maintain the nonspherical shape. Thus, our study provides guidelines for the production of spherical and nonspherical fat particles that can be potentially used for controlling microstructure, rheology, and drug encapsulation in foods, cosmetics, and pharmaceutical creams that employ crystallizable oils.

The prevalence of chronic and episodic migraine in children and adolescents.

BACKGROUND AND PURPOSE: Migraine is the most important cause of headache leading to a decrease in the quality of life in children and adolescents. The prevalence of episodic (EM) and chronic migraine (CM) increases with increasing age, which especially focused in recent years. METHODS: To evaluate the prevalence and determinants of migraine in children and adolescents, we performed this school-based epidemiological study. First part of the study was performed in 2001 that included 5562 children. Second part of the study was performed in 2007 in adolescents including 1155 young. After the main reports published, we made a new analysis in the database that focused on migraine. RESULTS: Totally, 10.4% of the children, predominantly the girls, received the diagnosis of migraine when they grew older (1.7% CM, 8.6% EM). CM frequency increased with increasing ages (doubled at 12 years, P = 0.035). The significant risk factors for having CM were found to be age, gender, and father and sibling headache histories. Most of the clinical characteristics of migraine are far from classical knowledge in children with CM. In adolescents, 18.6% were diagnosed as migraine (1.5%CM, 17.1%EM) with a predominance of girls without age difference. When they reached puberty after 6 years, double the number of cases with CM was headache free. Most of the young changed their headache characteristics during the follow-up period independent from management strategies. CONCLUSIONS: Our results showed that CM is an important cause of headache in both children and adolescents with some defining headache characteristics and risk factors concentrated in different age-groups.