Photonic crystals for light-emitting devices

Photonic crystals or photonic bandgap (PBG) structures promise to revolutionize optoelectronics by making anew class of highly efficient, low noise light emitters possible. We present data to show that their properties, in particular 2D systems, have now been fully characterized in the relevant semiconductor material system and at near-IR wavelengths, so effort can be redirected towards making active light emitters. As a first example, we present a semiconductor laser with one output mirror designed according to PBG principles. From threshold and efficiency data, we derive a reflectivity of 95 +/- 10 percent for this mirror, which underlines the viability of the PBG approach for practical devices. In order to realize the full potential of photonic crystal light emitters, however, important material issues need to be considered. Non- radiative recombination, for example, is a big problem when the photonic crystal is an integral part of the active region because of the relatively large areas of exposed surface. Several possible solutions to this problem are presented

Low Threshold Two-Dimensional Annular Bragg Lasers

Lasing at telecommunication wavelengths from annular resonators employing radial Bragg reflectors is demonstrated at room temperature under pulsed optical pumping. Sub milliwatt pump threshold levels are observed for resonators with 0.5-1.5 wavelengths wide defects of radii 7-8 mm. The quality factors of the resonator modal fields are estimated to be on the order of a few thousands. The electromagnetic field is shown to be guided by the defect. Good agreement is found between the measured and calculated spectrum.Comment: 8 pages, 4 figure

Signaling pathways in cell models of Fabry disease nephropathy

Chronic Kidney Disease is a leading cause of morbidity, impaired quality of life and premature death in patients with Fabry disease, being of major public health significance. At the cellular level, besides within lysosomes, glycosphingolipids that accumulate in Fabry disease due to alpha-galactosidase A (α-gal A) deficiency localize to membrane microdomains, which play crucial roles in protein clustering, membrane trafficking, and especially cell signaling. The mechanisms by which increased levels of these glycosphingolipids and consequent changes in microdomain dynamics and lysosomal dysfunction all result in cellular and organ injury are not well understood. To effectively study Fabry disease disease mechanisms at the cellular level, I first established and characterized an epithelial kidney cell model of Fabry disease in Madin-Darby canine kidney (MDCK) cells using small interfering RNA (siRNA). I then examined protein dynamics at the plasma membrane of a model raft-associated protein, GFP-GPI, in this model system. Number and Brightness Analysis in live cells showed a significant increase in the oligomeric size of antibody-induced clusters in α-gal A silenced cells compared to control cells (5.08 ± 0.45 vs 2.74 ± 0.24, respectively). To explore possible consequences of these findings in signaling pathways that are relevant to human disease, I first generated human kidney cell models of Fabry disease in immortalized podocytes and tubule epithelial cells (HK-2) applying the genome editing technique of clustered, regularly interspaced, short palindromic repeats and associated endonuclease 9 from S. pyogenes (CRISPR/Cas9). I compared abundance and phosphorylation of relevant signaling proteins through a high-throughput phosphorylation profiling for Fabry disease and control immortalized human podocytes. Fabry disease podocytes showed significant changes in total protein abundance and/or phosphorylation in 59 proteins. Pathway analysis predicted differential signaling of several canonical pathways in Fabry disease podocytes. These studies provided for the first time an understanding of raft protein dynamics and signaling in kidney cells deficient for α-gal A, potentially opening new avenues for biomarker discovery and drug development for Fabry disease nephropathy

The Tatton-Brown-Rahman Syndrome: A clinical study of 55 individuals with de novo constitutive DNMT3A variants.

Tatton-Brown-Rahman syndrome (TBRS; OMIM 615879), also known as the DNMT3A-overgrowth syndrome, is an overgrowth intellectual disability syndrome first described in 2014 with a report of 13 individuals with constitutive heterozygous DNMT3A variants. Here we have undertaken a detailed clinical study of 55 individuals with de novoDNMT3A variants, including the 13 previously reported individuals. An intellectual disability and overgrowth were reported in >80% of individuals with TBRS and were designated major clinical associations. Additional frequent clinical associations (reported in 20-80% individuals) included an evolving facial appearance with low-set, heavy, horizontal eyebrows and prominent upper central incisors; joint hypermobility (74%); obesity (weight ³2SD, 67%); hypotonia (54%); behavioural/psychiatric issues (most frequently autistic spectrum disorder, 51%); kyphoscoliosis (33%) and afebrile seizures (22%). One individual was diagnosed with acute myeloid leukaemia in teenage years. Based upon the results from this study, we present our current management for individuals with TBRS

VAMP7 modulates ciliary biogenesis in kidney cells

Epithelial cells elaborate specialized domains that have distinct protein and lipid compositions, including the apical and basolateral surfaces and primary cilia. Maintaining the identity of these domains is required for proper cell function, and requires the efficient and selective SNARE-mediated fusion of vesicles containing newly synthesized and recycling proteins with the proper target membrane. Multiple pathways exist to deliver newly synthesized proteins to the apical surface of kidney cells, and the post-Golgi SNAREs, or VAMPs, involved in these distinct pathways have not been identified. VAMP7 has been implicated in apical protein delivery in other cell types, and we hypothesized that this SNARE would have differential effects on the trafficking of apical proteins known to take distinct routes to the apical surface in kidney cells. VAMP7 expressed in polarized Madin Darby canine kidney cells colocalized primarily with LAMP2-positive compartments, and siRNA-mediated knockdown modulated lysosome size, consistent with the known function of VAMP7 in lysosomal delivery. Surprisingly, VAMP7 knockdown had no effect on apical delivery of numerous cargoes tested, but did decrease the length and frequency of primary cilia. Additionally, VAMP7 knockdown disrupted cystogenesis in cells grown in a three-dimensional basement membrane matrix. The effects of VAMP7 depletion on ciliogenesis and cystogenesis are not directly linked to the disruption of lysosomal function, as cilia lengths and cyst morphology were unaffected in an MDCK lysosomal storage disorder model. Together, our data suggest that VAMP7 plays an essential role in ciliogenesis and lumen formation. To our knowledge, this is the first study implicating an R-SNARE in ciliogenesis and cystogenesis. © 2014 Szalinski et al

Photonic crystals for light-emitting devices

Photonic crystals or photonic bandgap (PBG) structures promise to revolutionize optoelectronics by making anew class of highly efficient, low noise light emitters possible. We present data to show that their properties, in particular 2D systems, have now been fully characterized in the relevant semiconductor material system and at near-IR wavelengths, so effort can be redirected towards making active light emitters. As a first example, we present a semiconductor laser with one output mirror designed according to PBG principles. From threshold and efficiency data, we derive a reflectivity of 95 +/- 10 percent for this mirror, which underlines the viability of the PBG approach for practical devices. In order to realize the full potential of photonic crystal light emitters, however, important material issues need to be considered. Non- radiative recombination, for example, is a big problem when the photonic crystal is an integral part of the active region because of the relatively large areas of exposed surface. Several possible solutions to this problem are presented

Multiomic molecular patterns of lipid dysregulation in a subphenotype of sepsis with higher shock incidence and mortality

BackgroundLipids play a critical role in defense against sepsis. We sought to investigate gene expression and lipidomic patterns of lipid dysregulation in sepsis.MethodsData from four adult sepsis studies were analyzed and findings were investigated in two external datasets. Previously characterized lipid dysregulation subphenotypes of hypolipoprotein (HYPO; low lipoproteins, increased mortality) and normolipoprotein (NORMO; higher lipoproteins, lower mortality) were studied. Leukocytes collected within 24 h of sepsis underwent RNA sequencing (RNAseq) and shotgun plasma lipidomics was performed.ResultsOf 288 included patients, 43% were HYPO and 57% were NORMO. HYPO patients exhibited higher median SOFA scores (9 vs 5, p = < 0.001), vasopressor use (67% vs 34%, p = < 0.001), and 28-day mortality (30% vs 16%, p = 0.004). Leukocyte RNAseq identified seven upregulated lipid metabolism genes in HYPO (PCSK9, DHCR7, LDLR, ALOX5, PLTP, FDFT1, and MSMO1) vs. NORMO patients. Lipidomics revealed lower cholesterol esters (CE, adjusted p = < 0.001), lysophosphatidylcholines (LPC, adjusted p = 0.001), and sphingomyelins (SM, adjusted p = < 0.001) in HYPO patients. In HYPO patients, DHCR7 expression strongly correlated with reductions in CE, LPC, and SM (p < 0.01), while PCSK9, MSMO1, DHCR7, PLTP, and LDLR upregulation were correlated with low LPC (p < 0.05). DHCR7, ALOX5, and LDLR correlated with reductions in SM (p < 0.05). Mortality and phenotype comparisons in two external datasets (N = 824 combined patients) corroborated six of the seven upregulated lipid genes (PCSK9, DHCR7, ALOX5, PLTP, LDLR, and MSMO1).ConclusionWe identified a genetic lipid dysregulation signature characterized by seven lipid metabolism genes. Five genes in HYPO sepsis patients most strongly correlated with low CE, LPC, and SMs that mediate cholesterol storage and innate immunity

DHCR7 Expression Predicts Poor Outcomes and Mortality From Sepsis

This is a study of lipid metabolic gene expression patterns to discover precision medicine for sepsis.ObjectivesSepsis patients experience poor outcomes including chronic critical illness (CCI) or early death (within 14 d). We investigated lipid metabolic gene expression differences by outcome to discover therapeutic targets.Design setting and particitpantsSecondary analysis of samples from prospectively enrolled sepsis patients (first 24 hr) and a zebrafish endotoxemia model for drug discovery. Patients were enrolled from the emergency department or ICU at an urban teaching hospital. Enrollment samples from sepsis patients were analyzed. Clinical data and cholesterol levels were recorded. Leukocytes were processed for RNA sequencing and reverse transcriptase polymerase chain reaction. A lipopolysaccharide zebrafish endotoxemia model was used for confirmation of human transcriptomic findings and drug discovery.Main outcomes and measuresThe derivation cohort included 96 patients and controls (12 early death, 13 CCI, 51 rapid recovery, and 20 controls) and the validation cohort had 52 patients (6 early death, 8 CCI, and 38 rapid recovery).ResultsThe cholesterol metabolism gene 7-dehydrocholesterol reductase (DHCR7) was significantly up-regulated in both derivation and validation cohorts in poor outcome sepsis compared with rapid recovery patients and in 90-day nonsurvivors (validation only) and validated using RT-qPCR analysis. Our zebrafish sepsis model showed up-regulation of dhcr7 and several of the same lipid genes up-regulated in poor outcome human sepsis (dhcr24, sqlea, cyp51, msmo1, and ldlra) compared with controls. We then tested six lipid-based drugs in the zebrafish endotoxemia model. Of these, only the Dhcr7 inhibitor AY9944 completely rescued zebrafish from lipopolysaccharide death in a model with 100% lethality.ConclusionsDHCR7, an important cholesterol metabolism gene, was up-regulated in poor outcome sepsis patients warranting external validation. This pathway may serve as a potential therapeutic target to improve sepsis outcomes

Differentially expressed proteins in genetically edited human podocytes: contributing to the understanding of early molecular events in Fabry Disease / Proteínas diferencialmente expressas em podócitos humanos geneticamente editados: contribuições para elucidação dos eventos moleculares iniciais na doença de Fabry

Background: Podocyte damage and subsequent proteinuric chronic nephropathy are prominent features of Fabry Disease (FD), a multisystemic X-linked inherited lysosomal storage disorder caused by deficient activity of the alpha-galactosidase A (α-GAL A) enzyme following mutations in the GLA gene. Methods: A proteomic approach based on two-dimensional gel electrophoresis coupled with mass spectrometry was used to explore differentially expressed proteins in podocytes with α-GAL A deficiency. This deficiency was developed through GLA gene deletion using CRISPR/Cas9 genome-editing technology in an immortalized human podocyte culture cell line. To further validate our proteomic findings, we compared the expression of autophagy-specific biomarkers (LC3B and p62) using western blotting, as well as evaluated apoptosis using propidium iodide fluorescence microscopy. Results:  Our results showed that protein levels of ubiquitin carboxyl-terminal esterase L1, alpha-enolase, and heat shock protein 60 were reduced FD podocytes. Functional analysis using gene ontology found these proteins were predominately involved in biological processes, including autophagy regulation and apoptosis. Additionally, we found that autophagy-specific biomarkers LC3B and p62 were overexpressed, confirming impaired autophagy regulation and greater apoptosis in FD podocytes. Conclusions Our findings suggest impaired proteostasis in FD podocytes due to concomitant dysfunction of the ubiquitin–proteasome system and the autophagy pathway; both of which are potentially implicated in the pathogenesis of FD nephropathy