148 research outputs found
Metastable Pores at the Onset of Constant-Current Electroporation
Single metastable nanopores, appearing before the actual electroporation under constant-current conditions, are used to characterize the onset of electroporation. Unlike the long-lived electropores typical of the current controlled methods, these pores survive for milliseconds and observing them is possible due to slow development of electroporation, provided by the gradual accumulation of charges on a planar membrane. Analysis of the metastable pore appearance frequency and lifetime shows the first introductory stage of electroporation. During this stage two species of metastable pores open, the majority of very low conductance that seem not fully developed as hydrophilic electropores. The experiments reveal that voltage value defines the electroporation onset while the current value affects the rate of electroporation. Membrane capacitance has a great impact on the membrane susceptibility to the pore appearance, related to its thickness and integrity. Pores of nonperfect membranes appear more easily, but they do not live any longer than others
Add-On Cannabidiol Treatment for Drug-Resistant Seizures in Tuberous Sclerosis Complex A Placebo-Controlled Randomized Clinical Trial
IMPORTANCE Efficacy of cannabidiol has been demonstrated in seizures associated with
Lennox-Gastaut and Dravet syndromes but appears not yet to have been established in
conditions with primarily focal seizures, such as tuberous sclerosis complex (TSC).
OBJECTIVE To evaluate efficacy and safety of 25-mg/kg/day and 50-mg/kg/day cannabidiol
dosages vs placebo against seizures associated with TSC.
DESIGN, SETTING, AND PARTICIPANTS This double-blind, placebo-controlled randomized
clinical trial (GWPCARE6) enrolled patients between April 6, 2016, and October 4, 2018;
follow-up was completed on February 15, 2019. The trial was conducted at 46 sites in
Australia, Poland, Spain, the Netherlands, United Kingdom, and United States. Eligible
patients (aged 1-65 years) were those with a clinical diagnosis of TSC and medicationresistant
epilepsy who had had at least 8 TSC-associated seizures during the 4-week baseline
period, with at least 1 seizure occurring in at least 3 of the 4 weeks, and were currently taking
at least 1 antiepileptic medication.
INTERVENTIONS Patients received oral cannabidiol at 25mg/kg/day (CBD25) or 50
mg/kg/day (CBD50) or a matched placebo for 16 weeks.
MAIN OUTCOMES AND MEASURES The prespecified primary outcomewas the change from
baseline in number of TSC-associated seizures for cannabidiol vs placebo during the
treatment period.
RESULTS Of 255 patients screened for eligibility, 31 were excluded and 224 were randomized.
Of the 224 included patients (median [range] age, 11.4 [1.1-56.8] years; 93 female patients
[41.5%]), 75 were randomized to CBD25, 73 to CBD50, and 76 to placebo, with 201
completing treatment. The percentage reduction from baseline in the type of seizures
considered the primary end point was 48.6%(95%CI, 40.4%-55.8%) for the CBD25 group,
47.5%(95%CI, 39.0%-54.8%) for the CBD50 group, and 26.5%(95%CI, 14.9%-36.5%) for
the placebo group; the percentage reduction from placebo was 30.1% (95%CI, 13.9%-43.3%;
P < .001) for the CBD25 group and 28.5%(95%CI, 11.9%-42.0%; nominal P = .002) for the
CBD50 group. The most common adverse events were diarrhea (placebo group, 19 [25%];
CBD25 group, 23 [31%]; CBD50 group, 41 [56%]) and somnolence (placebo group, 7 [9%];
CBD25 group, 10 [13%]; CBD50 group, 19 [26%]), which occurred more frequently with
cannabidiol than placebo. Eight patients in CBD25 group, 10 in CBD50 group, and 2 in the
placebo group discontinued treatment because of adverse events. Twenty-eight patients
taking cannabidiol (18.9%) had elevated liver transaminase levels vs none taking placebo.
CONCLUSIONS AND RELEVANCE Cannabidiol significantly reduced TSC-associated seizures
compared with placebo. The 25-mg/kg/day dosage had a better safety profile than the
50-mg/kg/day dosage.
TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0254476
Upconversion FRET quantitation: the role of donor photoexcitation mode and compositional architecture on the decay and intensity based responses
Lanthanide-doped colloidal nanoparticles capable of photon upconversion (UC) offer long luminescence lifetimes, narrowband absorption and emission spectra, and efficient anti-Stokes emission. These features are highly advantageous for Forster Resonance Energy Transfer (FRET) based detection. Upconverting nanoparticles (UCNPs) as donors may solve the existing problems of molecular FRET systems, such as photobleaching and limitations in quantitative analysis, but these new labels also bring new challenges. Here we have studied the impact of the core-shell compositional architecture of upconverting nanoparticle donors and the mode of photoexcitation on the performance of UC-FRET from UCNPs to Rose Bengal (RB) molecular acceptor. We have quantitatively compared luminescence rise and decay kinetics of Er3+ emission using core-only NaYF4: 20% Yb, 2% Er and core-shell NaYF4: 20% Yb @ NaYF4: 20% Yb, 5% Er donor UCNPs under three photoexcitation schemes: (1) direct short-pulse photoexcitation of Er3+ at 520 nm; indirect photoexcitation of Er3+ through Yb3+ sensitizer with (2) 980 nm short (5-7 ns) or (3) 980 nm long (4 ms) laser pulses. The donor luminescence kinetics and steady-state emission spectra differed between the UCNP architectures and excitation schemes. Aiming for highly sensitive kinetic upconversion FRET-based biomolecular assays, the experimental results underline the complexity of the excitation and energy-migration mechanisms affecting the Er3+ donor responses and suggest ways to optimize the photoexcitation scheme and the architecture of the UCNPs used as luminescent donors
Giant nonlinear optical responses from photon avalanching nanoparticles
Avalanche phenomena leverage steeply nonlinear dynamics to generate
disproportionately high responses from small perturbations and are found in a
multitude of events and materials, enabling technologies including optical
phase-conjugate imaging, infrared quantum counting, and efficient upconverted
lasing. However, the photon avalanching (PA) mechanism underlying these optical
innovations has been observed only in bulk materials and aggregates, and
typically at cryogenic temperatures, limiting its utility and impact. Here, we
report the realization of PA at room temperature in single
nanostructures--small, Tm-doped upconverting nanocrystals--and demonstrate
their use in superresolution imaging at near-infrared (NIR) wavelengths within
spectral windows of maximal biological transparency. Avalanching nanoparticles
(ANPs) can be pumped by continuous-wave or pulsed lasers and exhibit all of the
defining features of PA. These hallmarks include excitation power thresholds,
long rise time at threshold, and a dominant excited-state absorption that is
>13,000x larger than ground-state absorption. Beyond the avalanching threshold,
ANP emission scales nonlinearly with the 26th power of pump intensity. This
enables the realization of photon-avalanche single-beam superresolution imaging
(PASSI), achieving sub-70 nm spatial resolution using only simple scanning
confocal microscopy and before any computational analysis. Pairing their steep
nonlinearity with existing superresolution techniques and computational
methods, ANPs allow for imaging with higher resolution and at ca. 100-fold
lower excitation intensities than is possible with other probes. The low PA
threshold and exceptional photostability of ANPs also suggest their utility in
a diverse array of applications including sub-wavelength bioimaging, IR
detection, temperature and pressure transduction, neuromorphic computing, and
quantum optics.Comment: 14 pages, 4 figure
Subependymal giant cell astrocytomas are characterized by mTORC1 hyperactivation, a very low somatic mutation rate, and a unique gene expression profile
Subependymal giant-cell astrocytomas (SEGAs) are slow-growing brain tumors that are a hallmark feature seen in 5–10% of patients with Tuberous Sclerosis Complex (TSC). Though histologically benign, they can cause serious neurologic symptoms, leading to death if untreated. SEGAs consistently show biallelic loss of TSC1 or TSC2. Herein, we aimed to define other somatic events beyond TSC1/TSC2 loss and identify potential transcriptional drivers that contribute to SEGA formation. Paired tumor-normal whole-exome sequencing was performed on 21 resected SEGAs from 20 TSC patients. Pathogenic variants in TSC1/TSC2 were identified in 19/21 (90%) SEGAs. Copy neutral loss of heterozygosity (size range: 2.2–46 Mb) was seen in 76% (16/21) of SEGAs (44% chr9q and 56% chr16p). An average of 1.4 other somatic variants (range 0–7) per tumor were identified, unlikely of pathogenic significance. Whole transcriptome RNA-sequencing analyses revealed 190 common differentially expressed genes in SEGA (n = 16, 13 from a prior study) in pairwise comparison to each of: low grade diffuse gliomas (n = 530) and glioblastoma (n = 171) from The Cancer Genome Atlas (TCGA) consortium, ganglioglioma (n = 10), TSC cortical tubers (n = 15), and multiple normal tissues. Among these, homeobox transcription factors (TFs) HMX3, HMX2, VAX1, SIX3; and TFs IRF6 and EOMES were all expressed >12-fold higher in SEGAs (FDR/q-value < 0.05). Immunohistochemistry supported the specificity of IRF6, VAX1, SIX3 for SEGAs in comparison to other tumor entities and normal brain. We conclude that SEGAs have an extremely low somatic mutation rate, suggesting that TSC1/TSC2 loss is sufficient to drive tumor growth. The unique and highly expressed SEGA-specific TFs likely reflect the neuroepithelial cell of origin, and may also contribute to the transcriptional and epigenetic state that enables SEGA growth following two-hit loss of TSC1 or TSC2 and mTORC1 activation
Serum cystatin C level in patients with rheumatoid arthritis after single infusion of infliximab
Early diagnosis of tuberous sclerosis complex: A race against time. How to make the diagnosis before seizures?
Background: Tuberous sclerosis complex (TSC) is a genetic disorder with an incidence of 1:6000 live births and associated with the development of benign tumors in several organs. It is also characterized by high rates of neurological and neuropsychiatric abnormalities, including epilepsy affecting 70-90% of patients and being one of the major risk factors of intellectual disability. The first seizures in TSC patients appear usually between the 4th and the 6th months of life. Recent studies have shown the beneficial role of preventative antiepileptic treatment in TSC patients, with the possibility for improvement of cognitive outcome. Moreover, European recommendations suggest early introduction of Vigabatrin if ictal discharges occur on EEG recordings, with or without clinical manifestation. The aim of this study was to define the most useful approach to make the diagnosis of TSC before seizure onset (before age 4th months), in order to start early EEG monitoring with possible preventative treatment intervention. Methods: We performed a retrospective review of children who were suspected of having TSC due to single or multiple cardiac tumors as the first sign of the disease. We analyzed the medical records in terms of conducted clinical tests and TSC signs, which were observed until the end of the 4th month of age. Subsequently, we described the different clinical scenarios and recommendations for early diagnosis. Results: 82/100 children were diagnosed with TSC within the first 4 months of life. Apart from cardiac tumors, the most frequently observed early TSC signs were subependymal nodules (71/100, 71%), cortical dysplasia (66/100, 66%), and hypomelanotic macules (35/100, 35%). The most useful clinical studies for early TSC diagnosis were brain magnetic resonance imaging (MRI), skin examination and echocardiography. Genetic testing was performed in 49/100 of the patients, but the results were obtained within the first 4 months of life in only 3 children. Conclusions: Early diagnosis of TSC, before seizure onset, is feasible and it is becoming pivotal for epilepsy management and improvement of cognitive outcome. Early TSC diagnosis is mostly based on clinical signs. Brain MRI, echocardiography, skin examination and genetic testing should be performed early in every patient suspected of having TSC
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