Light-activated microtubule-based two-dimensional active nematic.

We assess the ability of two light responsive kinesin motor clusters to drive dynamics of microtubule-based active nematics: opto-K401, a processive motor, and opto-K365, a non-processive motor. Measurements reveal an order of magnitude improvement in the contrast of nematic flow speeds between maximally- and minimally-illuminated states for opto-K365 motors when compared to opto-K401 construct. For opto-K365 nematics, we characterize both the steady-state flow and defect density as a function of applied light. We also examine the transient behavior as the system switches between steady-states upon changes in light intensities. Although nematic flows reach a steady state within tens of seconds, the defect density exhibits transient behavior for up to 10 minutes, showing a separation between small-scale active flows and system-scale structural states. Our work establishes an experimental platform that can exploit spatiotemporally-heterogeneous patterns of activity to generate targeted dynamical states.

Diffusing wave microrheology of highly scattering concentrated monodisperse emulsions.

Motivated by improvements in diffusing wave spectroscopy (DWS) for nonergodic, highly optically scattering soft matter and by cursory treatment of collective scattering effects in prior DWS microrheology experiments, we investigate the low-frequency plateau elastic shear moduli [Formula: see text] of concentrated, monodisperse, disordered oil-in-water emulsions as droplets jam. In such experiments, the droplets play dual roles both as optical probes and as the jammed objects that impart shear elasticity. Here, we demonstrate that collective scattering significantly affects DWS mean-square displacements (MSDs) in dense colloidal emulsions. By measuring and analyzing the scattering mean free path as a function of droplet volume fraction φ, we obtain a φ-dependent average structure factor. We use this to correct DWS MSDs by up to a factor of 4 and then calculate [Formula: see text] predicted by the generalized Stokes-Einstein relation. We show that DWS-microrheological [Formula: see text] agrees well with mechanically measured [Formula: see text] over about three orders of magnitude when droplets are jammed but only weakly deformed. Moreover, both of these measurements are consistent with predictions of an entropic-electrostatic-interfacial (EEI) model, based on quasi-equilibrium free-energy minimization of disordered, screened-charge-stabilized, deformable droplets, which accurately describes prior mechanical measurements of [Formula: see text] made on similar disordered monodisperse emulsions over a wide range of droplet radii and φ. This very good quantitative agreement between DWS microrheology, mechanical rheometry, and the EEI model provides a comprehensive and self-consistent view of weakly jammed emulsions. Extensions of this approach may improve DWS microrheology on other systems of dense, jammed colloids that are highly scattering.

Observation of Strongly Heterogeneous Dynamics at the Depinning Transition in a Colloidal Glass.

We study experimentally the origin of heterogeneous dynamics in strongly driven glass-forming systems. Thereto, we apply a well-defined force with a laser line trap on individual colloidal polystyrene probe particles seeded in an emulsion glass composed of droplets of the same size. Fluid and glass states can be probed. We monitor the trajectories of the probe and measure displacements and their distributions. Our experiments reveal intermittent dynamics around a depinning transition at a threshold force. For smaller forces, linear response connects mean displacement, and quiescent mean squared displacement. Mode coupling theory calculations rationalize the observations.

Deformation of the contact line around spherical particles bound at anisotropic fluid interfaces.

When a particle adsorbs at a liquid interface, the 3-phase contact line geometry depends on the shape of the particle and of the liquid interface. The shape of the contact line is the key to controlling capillary forces among particles, and is therefore a useful means to direct assembly of interfacial particles. We measured the shape of the contact line around millimeter-sized PDMS-coated glass spheres at water/air interfaces with anisotropic shapes. We studied the advancing and receding conditions separately. We focused on interfaces with a cylindrical shape, where the predominant deformation of the meniscus and the contact line both have quadrupolar cos(2ϕ) symmetry. We related the measured magnitude of the quadrupolar deformation to the applied vertical force on the sphere and the interface's deviatoric curvature, D0. For modest curvature (D0 < 0.1 × sphere radius), our results agree with the theoretical prediction for free particles. At higher curvature, the measurements exceed the theory. The theory appears to apply even when there is contact-angle hysteresis, as long as the measured contact angle is used rather than the equilibrium (Young-Dupré) angle. The magnitude of the quadrupolar deformation depends on the applied force. Together, these results show the range of validity of the theory.

Measured capillary forces on spheres at particle-laden interfaces.

We measure capillary forces on particles at fluid interfaces in order to assess the key parameters that yield effective stabilizing particles. In our experiments, a millimeter-scale particle is attached to a cantilever, which is used to pull the particle perpendicular to the interface. Simultaneously, we image from the side to measure the cantilever's deflection and thus the pulling force, as well as the height of the particle and the shape of the interface. We find that the peak force on a particle at an interface crowded with other particles is consistently smaller than the force at a clean interface. This result is independent of the difference in fluid mass densities, the material of the target sphere, and the capillary charge of the free particles. We attribute the force reduction to the perturbation of interface shape due to the constraints at the boundaries of the free particles. The results should be helpful in designing particles to stabilize droplets in new oil dispersants or in other applications.

Effect of interface shape on advancing and receding fluid-contact angles around spherical particles.

The angle of contact between a solid surface and a fluid interface plays a key role in wetting and is therefore a focus in studies of a wide range of natural phenomena and fluidic technologies. The contact angle ranges between two values, a maximum (advancing) angle and a minimum (receding) angle. These limiting angles are thought to be properties of the fluids and of the chemistry or topography of the solid. By contrast, we find that the value of the receding angle can be significantly reduced by altering the interface shape. Using millimeter-sized spheres coated with polydimethylsiloxane and pulled through an air-water interface, we observe that the receding angle decreases from 101 ± 1° at a planar interface to as low as 80 ± 1° at saddle- or cylinder-shaped interfaces. The angle decreases smoothly with the deviatoric curvature of the interface (a measure of the shape anisotropy) and is linked to a non-circular contact line.

A Case of Early Infantile Epileptic Encephalopathy Due to KCNQ2 Gene Mutation Presenting With Episodes of Hiccups.

Neonatal epilepsy syndromes are responsible for only 15% of the cases of neonatal seizure. An underlying genetic disorder can be detected in approximately 42% of this subgroup. KCNQ2 gene-associated epilepsies are very rare and more common presentations are self-limited familial neonatal epilepsy (SLFNE) and early infantile epileptic encephalopathies (EIEE). The most common initial seizure semiologies are tonic seizures with or without autonomic symptoms in EIEE resulting from KCNQ2 gene mutation. It is characterized by early neonatal onset seizures with suppression burst pattern on electroencephalogram and typically results in severe developmental delay. Therapeutic options for infants with KCNQ2-related EIEE are limited and there is no consensus about it in the literature. Herein, the neonate with EIEE with unexpected episodes of hiccups due to novel mutation of the KCNQ2 gene, which was reported second time, was presented and antiepileptic treatment strategies were discussed in the light of current literature.

A Case Report of a Prenatally Missed Mowat-Wilson Syndrome With Isolated Corpus Callosum Agenesis.

Mowat-Wilson syndrome (MWS) is an autosomal dominant genetic disorder caused by ZEB2 gene mutations, manifesting with unique facial characteristics, moderate to severe intellectual problems, and congenital malformations as Hirschsprung disease, genital and ophthalmological anomalies, and congenital cardiac anomalies. Herein, a case of 1-year-old boy with isolated agenesis of corpus callosum (IACC) in the prenatal period is presented. He was admitted postnatally with Hirschsprung disease (HSCR), hypertelorism, uplifted earlobes, deeply set eyes, frontal bossing, oval-shaped nasal tip, ''M'' shaped upper lip, opened mouth and prominent chin, and developmental delay. Hence, MWS was primarily considered and confirmed by the ZEB2 gene mutation analysis. His karyotype was normal. He had a history of having a prenatally terminated brother with similar features. Antenatally detected IACC should prompt a detailed investigation including karyotype and microarray; even if they are normal then whole exome sequencing (WES) should be done.

A rare cause of mental motor retardation: recessive congenital methemoglobinemia type II.

Recessive congenital methemoglobinemia (RCM) is a very rare disorder caused by NADH- cytochrome b5 reductase (cytb5r) deficiency. It has been classified into four types. Type I presents with mild cyanosis due to a significant deficiency of cytb5r in erythrocytes only. In type II, the deficiency occurs in all tissues and causes growth and mental retardation and other neurological impairments. RCM types I and II are caused by a defect in a single gene, which is located on chromosome 22 (locus DIA 1: q 13.31-qter). Prenatal diagnosis is possible. Cyanosis can be well treated by 200-500 mg of ascorbic acid daily; there is no effective therapy for the progressive neurological impairments. This report presents two siblings with central cyanosis, growth retardation, mental retardation, microcephaly, dystonia and hypertonia diagnosed as RCM type II.

Genetic and clinical heterogeneity in eIF2B-related disorder.

Eukaryotic initiation factor 2B (eIF2B)-related disorders are heritable white matter disorders with a variable clinical phenotype (including vanishing white matter disease and ovarioleukodystrophy) and an equally heterogeneous genotype. We report 9 novel mutations in the EIF2B genes in our subject population, increasing the number of known mutations to more than 120. Using homology modeling, we have analyzed the impact of novel mutations on the 5 subunits of the eIF2B protein. Although recurrent mutations have been found at CpG dinucleotides in the EIF2B genes, the high incidence of private or low frequency mutations increases the challenge of providing rapid genetic confirmation of this disorder, and limits the application of EIF2B screening in cases of undiagnosed leukodystrophy.

Attitudes of parents and physicians toward febrile seizures.

OBJECTIVES: Although febrile seizures are common in children, attitudes may change among parents. The management of a child may differ depending on the specialty of the attending physician. This study was carried out to analyze attitudes of Turkish parents and physicians toward febrile seizures. MATERIAL AND METHODS: 308 children with febrile seizure who were admitted to the Department of Pediatric Neurology at Dr Sami Ulus Children's Hospital and Gazi University in Turkey between January 2006 and March 2007 were enrolled. RESULTS: Prior to seizure, approximately half of the parents took appropriate steps in reducing fever. The data also showed that there was a wide variation of treatment practice depending on the specialty of the attending physician. DISCUSSION: Educational level and economic status are important variables affecting attitudes of parents toward fever and febrile seizure. The management of the child with a febrile seizure differs even within the same specialty in Turkish physicians.

Devic's neuromyelitis optica in an infant case.

Devic's neuromyelitis optica was orginally described as an acute severe monophasic syndrome characterised by myelitis and optic neuritis. The mean age at onset was reported to be around 40 years, with a wide range. However, Devic's neuromyelitis optica has also been seen in children. Prognosis of the syndrome was poor, and no satisfactory treatment was known. This article reports a 23-month-old boy with acute myelitis and optic neuritis who was diagnosed with Devic's neuromyelitis optica. The response of the patient to therapy was poor, and he developed severe sequelae.

Prevalence of some risk factors in children with epilepsy compared to their controls.

AIM: The goal of this case-control study was to identify the significance of certain risk factors for epilepsy in Turkey. METHOD: A total of 805 cases, aged 1-16 years, followed-up for epilepsy at the Pediatric Neurology Department and a control group consisting of 846 age-matched cases without epilepsy were included in the study. The risk factors examined were gender, neurological impairment, febrile convulsion, head trauma, central nervous system infections, parental consanguinity, family history of epilepsy, prenatal and natal risk and newborn jaundice. Data regarding the investigated epilepsy risk factors were obtained through a questionnaire via personal interviews and the medical records and were assessed using univariate and multivariate analysis. RESULT: Univariate analysis showed an increased risk for epilepsy with a history of atypical febrile seizure (21.97-fold), severe and moderate head injury (27.76- and 7.09-fold respectively), CNS infection (4.76-fold), history of epilepsy in first-, second- or third-degree relatives (6.42-, 3.09- and 2.66-fold, respectively), presence of maternal hypertension (4.31-fold), an apgar score < or =6 at any time (7.78-fold) and neonatal jaundice (3.12-fold). Abnormal neurological signs increased the epilepsy risk 5.92 times in univariate analysis and 30.26 times in multivariate analysis. CONCLUSION: The most important risk factors for epilepsy in this study were neurological impairment, history of atypical febrile seizures, severe head injury and a low apgar score. Other important risk factors were moderate head trauma and a history of epilepsy in the family.

Doxycycline in autoimmune central nervous system disorders in children: an in vitro study.

Tetracyclines have antiinflammatory properties. To test the in vitro effect of doxycycline in autoimmune neurological disorders of childhood, peripheral blood lymphocytes from multiple sclerosis (n=11), acute disseminated encephalomyelitis (n=12), and control patients (epilepsy and headache, n=12), all aged 5-17, were examined for proliferation, migration, and apoptosis after culture with doxycycline, concanavalin A and myelin basic protein for 48 hours. Doxycycline increased proliferation in the control group, and less in the multiple sclerosis group but not in the acute disseminated encephalomyelitis group (p<0.03). It increased apoptosis in multiple sclerosis patients (p<0.02). According to this preliminary study, doxycycline might have immunomodulatory effects in children, justifying future studies with larger and more homogeneous patient groups.

The liquid-glass-jamming transition in disordered ionic nanoemulsions.

In quenched disordered out-of-equilibrium many-body colloidal systems, there are important distinctions between the glass transition, which is related to the onset of nonergodicity and loss of low-frequency relaxations caused by crowding, and the jamming transition, which is related to the dramatic increase in elasticity of the system caused by the deformation of constituent objects. For softer repulsive interaction potentials, these two transitions become increasingly smeared together, so measuring a clear distinction between where the glass ends and where jamming begins becomes very difficult or even impossible. Here, we investigate droplet dynamics in concentrated silicone oil-in-water nanoemulsions using light scattering. For zero or low NaCl electrolyte concentrations, interfacial repulsions are soft and longer in range, this transition sets in at lower concentrations, and the glass and the jamming regimes are smeared. However, at higher electrolyte concentrations the interactions are stiffer, and the characteristics of the glass-jamming transition resemble more closely the situation of disordered elastic spheres having sharp interfaces, so the glass and jamming regimes can be distinguished more clearly.

Nonconvulsive status epilepticus on electroencephalography in a case with subacute sclerosing panencephalitis.

Subacute sclerosing panencephalitis is a neurodegenerative disease with a poor prognosis. We report a case of a 5 1/2-year-old boy who had emotional lability, cognitive difficulties, and myoclonia after a mild closed head injury. The magnetic resonance image of the brain and computed tomographic scan of the head were normal. His electroencephalogram (EEG) showed continuous nonconvulsive status epilepticus activity, which could not be suppressed with intravenous diazepam. After treatment with phenytoin for 2 days, an EEG showed periodic high-amplitude sharp-and-slow-wave complexes, which were also not suppressed with intravenous diazepam. Since the patient had measles at 5 months of age, subacute sclerosing panencephalitis was considered, and the diagnosis was confirmed by the presence of measles antibodies in cerebrospinal fluid.

Subacute sclerosing panencephalitis: is there something different in the younger children?

Subacute sclerosing panencephalitis is a rare, slow viral infection caused by a defective measles virus. Although it is a rare disease, it is still important in developing countries. The onset is generally between the ages of 5-15 years. We reported the clinical and laboratory profile and nature of 9 patients under the age of 4 years with SSPE. Although it is known that a few patients with SSPE have an acute and rapidly fulminating course, in this study rate of progression was rapidly progressive in 6 patients and progressive in 3 of them on admission. Unfortunately, 4 of them were lost to follow up because of address and/or telephone number alterations. Although the number of patients in this study is not sufficient, we suggest that SSPE patients under the age of 4 years have a poor prognosis as a result of progressive or rapidly progressive course despite medical treatment.

Fixation-off sensitivity and generalized epileptic EEG induced by eyes closed.

This report describes a female with eyelid fluttering with absence seizures, infrequent generalized tonic-clonic seizures, and mild mental retardation. Interictal and video-electroencephalography evaluations revealed normal activity while eyes were open but continuous generalized discharges with eyes closed (eyes closed induced abnormality), as well as fixation-off sensitivity. This patient is in the group of a pure and distinct clinical form of fixation-off sensitivity cryptogenic generalized epilepsy.

Diagnostic criteria of pediatric migraine without aura.

The objectives of this study were to assess the validity of the International Classification of Headache Disorders-I (ICHD-I) and the International Headache Society-Revised (IHS-R) criteria and to evaluate the other headache features that are not included in these criteria for migraine without aura in the pediatric population. One hundred and thirty-two children who referred to our clinic with the complaint of chronic or recurrent headache were evaluated. Clinical diagnosis of the pediatric neurologist was used as the gold standard in evaluating the validity of ICHD-I and IHS-R criteria and the other headache features. After eliminating patients with other migraine types, secondary headache, and missing data, 92 patients were included in the study according to their records. Sixty-one children (66.3%) were diagnosed as migraine without aura. Using the clinical diagnosis as the gold standard, the specificity of ICHD-I criteria was detected as 93.5%, while the sensitivity was detected as 36.1%. IHS-R criteria had 90.3% specificity and 78.7% sensitivity. Relief of headache with sleeping or lying down in a dark, quiet room was found to be the highest specific and sensitive factor of the other headache features not included in these criteria. IHS-R criteria were found to be more valid in the diagnosis of migraine without aura than ICHD-I criteria. IHS-R criteria are recommended both in clinical practice and in the studies requiring migraine without aura case definitions in the pediatric population.

Tracing immature myelin in acute disseminated encephalomyelitis.

Inherent abnormalities of myelin have been suggested in the pathogenesis of multiple sclerosis (MS). We investigated myelin in acute disseminated encephalomyelitis (ADEM) patients by magnetic resonance spectroscopy (MRS) and cerebrospinal fluid (CSF) analysis for citrulline, a marker of immature myelin. A citrulline peak was observed in the normal appearing white matter of 7/15 patients and of 1/10 age-matched neurological controls (p=0.08). CSF citrulline was elevated in 4/6 patients. Alterations in the composition of myelin might predispose to or follow acute inflammatory disorders of the central nervous system.