Diverse hepatitis C virus glycoproteins mediate viral infection in a CD81-dependent manner

We recently reported that retroviral pseudotypes bearing the hepatitis C virus (HCV) strain H and Con1 glycoproteins, genotype 1a and 1b, respectively, require CD81 as a coreceptor for virus-cell entry and infection. Soluble truncated E2 cloned from a number of diverse HCV genotypes fail to interact with CD81, suggesting that viruses of diverse origin may utilize different receptors and display altered cell tropism. We have used the pseudotyping system to study the tropism of viruses bearing diverse HCV glycoproteins. Viruses bearing these glycoproteins showed a 150-fold range in infectivity for hepatoma cells and failed to infect lymphoid cells. The level of glycoprotein incorporation into particles varied considerably between strains, generally reflecting the E2 expression level within transfected cells. However, differences in glycoprotein incorporation were not associated with virus infectivity, suggesting that infectivity is not limited by the absolute level of glycoprotein. All HCV pseudotypes failed to infect HepG2 cells and yet infected the same cells after transduction to express human CD81, confirming the critical role of CD81 in HCV infection. Interestingly, these HCV pseudotypes differed in their ability to infect HepG2 cells expressing a panel of CD81 variants, suggesting subtle differences in the interaction of CD81 residues with diverse viral glycoproteins. Our current model of HCV infection suggests that CD81, together with additional unknown liver specific receptor(s), mediate the virus-cell entry process

Probing Lyman-alpha Absorbers in Cosmological Simulations with Double Lines of Sight

We perform a double line of sight (DLOS) analysis of the Lyman-alpha forest structures that form and evolve in cosmological N-body/hydrodynamic simulations. Pairs of simulated spectra, extracted from lines of sight separated by distances from D=12.5kpc up to 800kpc, and a ``control sample'' of unrelated lines of sight, are analyzed at redshifts 3, 2, and 1. Coincident line samples are defined for HI column density thresholds of Nco = 10^{12.5}, 10^{13}, and 10^{14} per square cm. We find that: 1) Under the assumption of a single structure size, a Bayesian analysis yields sizes that are larger for smaller Nco, and at fixed Nco the size decreases with decreasing redshift. However, these derived sizes are found to increase with increasing D indicating that the assumption of a single structure size is invalid. 2) The column densities of coincident pairs are highly correlated for small D, with increasing scatter as D is increased, consistent with structures that have a centrally peaked N(HI) that decreases gradually with radius. 3) The velocity difference distribution for coincident lines is very narrow for small D, and widens as D is increased to meet the expectation for chance coincidences in unrelated lines of sight. This behavior is indicative of organized motion within the structures. 4) For small D, the distribution of anticoincident line column densities, Nac, falls steeply as Nac increases from the cutoff value, but has a significant tail at large values which is inconsistent with a population of spherical absorbers with sharp edges, and consistent with a flattened geometry. The conclusions reached on the basis of the DLOS analysis are validated by an examination of the three-dimensional structures and velocity flows in the simulation data.Comment: 17 pages, Latex file, and 8 PostScript figures; Submitted to the Astrophysical Journal; Available as a single compressed Postscript file at http://www.astro.psu.edu/users/charlto

Modulation of anabolic and catabolic responses via a porous polymer scaffold manufactured using thermally induced phase separation

We describe two studies encompassing the iterative refinement of a polymer-based rhBMP-2 delivery system for bone tissue engineering. Firstly, we compared the boneforming capacity of porous poly(D,L-lactic-co-glycolic acid) (PLGA) scaffolds produced by thermally induced phase separation (TIPS) with non-porous solvent cast poly(D,L-lactic acid) (PDLLA) used previously. Secondly, we examined the potential synergy between rhBMP-2 and local bisphosphonate in the PLGA scaffold system. In vivo ectopic bone formation studies were performed in C57BL6/J mice. Polymer scaffolds containing 0, 5, 10 or 20 μg rhBMP-2 were inserted into the dorsal musculature. At all rhBMP-2 doses, porous PLGA produced significantly higher bone volume (BV, mm) than the solid PDLLA scaffolds. Next, porous PLGA scaffolds containing 10μg rhBMP-2 ±0.2, or 2μg zoledronic acid (ZA) were inserted into the hind-limb musculature. Co-delivery of local 10μg rhBMP-2/2μg ZA significantly augmented bone formation compared with rhBMP-2 alone (400 % BV increase, p < 0.01). Hydroxyapatite microparticle (HAp) addition (2% w/w) to the 10μg rhBMP-2/0.2μg ZA group increased BV (200 %, p < 0.01). We propose that this was due to controlled ZA release of HAp-bound ZA. Consistent with this, elution analyses showed that HAp addition did not alter the rhBMP-2 elution, but delayed ZA release. Moreover, 2 % w/w HAp addition reduced the scaffold's compressive properties, but did not alter ease of surgical handling. In summary, our data show that refinement of the polymer selection and scaffold fabrication can enhance rhBMP-2 induced bone formation in our bone tissue engineering implant, and this can be further optimised by the local co-delivery of ZA/HAp

Effects of acute normobaric hypoxia on memory interference

© 2019 by the authors. Licensee MDPI, Basel, Switzerland. Purpose: Previous research has evaluated the effects of acute hypoxia exposure on cognitive function, notably executive function. No studies, to date, have evaluated the effects of acute hypoxia exposure on memory interference, which was the purpose of this experiment. Methods: A within-subjects, counterbalanced experimental design was employed, with condition (hypoxia vs. normoxia) and time (immediate vs. delayed) being the independent variables. Participants (N = 21; Mage = 21.0 years) completed two laboratory visits, involving 30 min of exposure to either hypoxia (FIO2 = 0.12) or normoxia (FIO2 = 0.21). Following this, they completed a memory interference task (AB/AC paradigm), assessing immediate and delayed proactive and retroactive interference. Results: For retroactive interference, we observed a significant main effect for condition, F(1, 20) = 5.48, p = 0.03, η2 = 0.10, condition by time interaction, F(1, 20) = 4.96, p = 0.03, η2 = 0.01, but no main effect for time, F(1, 20) = 1.75, p = 0.20, η2 = 0.004. Conclusion: Our results demonstrate that acute hypoxia exposure was facilitative in reducing memory interference. We discuss these findings in the context of the potential therapeutic effects of acute hypoxia exposure on synaptic plasticity

MicroRNA-21 is Induced by Rapamycin in a Model of Tuberous Sclerosis (TSC) and Lymphangioleiomyomatosis (LAM)

Lymphangioleiomyomatosis (LAM), a multisystem disease of women, is manifest by the proliferation of smooth muscle-like cells in the lung resulting in cystic lung destruction. Women with LAM can also develop renal angiomyolipomas. LAM is caused by mutations in the tuberous sclerosis complex genes (TSC1 or TSC2), resulting in hyperactive mammalian Target of Rapamycin (mTOR) signaling. The mTOR inhibitor, Rapamycin, stabilizes lung function in LAM and decreases the volume of renal angiomyolipomas, but lung function declines and angiomyolipomas regrow when treatment is discontinued, suggesting that factors induced by mTORC1 inhibition may promote the survival of TSC2-deficient cells. Whether microRNA (miRNA, miR) signaling is involved in the response of LAM to mTORC1 inhibition is unknown. We identified Rapamycin-dependent miRNA in LAM patient angiomyolipoma-derived cells using two separate screens. First, we assayed 132 miRNA of known significance to tumor biology. Using a cut-off of >1.5-fold change, 48 microRNA were Rapamycin-induced, while 4 miRs were downregulated. In a second screen encompassing 946 miRNA, 18 miRs were upregulated by Rapamycin, while eight were downregulated. Dysregulation of miRs 29b, 21, 24, 221, 106a and 199a were common to both platforms and were classified as candidate “RapamiRs.” Validation by qRT-PCR confirmed that these microRNA were increased. miR-21, a pro-survival miR, was the most significantly increased by mTOR-inhibition (p<0.01). The regulation of miR-21 by Rapamycin is cell type independent. mTOR inhibition promotes the processing of the miR-21 transcript (pri-miR-21) to a premature form (pre-miR-21). In conclusion, our findings demonstrate that Rapamycin upregulates multiple miRs, including pro-survival miRs, in TSC2-deficient patient-derived cells. The induction of miRs may contribute to the response of LAM and TSC patients to Rapamycin therapy

Development of 68Ga-Glycopeptide as an Imaging Probe for Tumor Angiogenesis

Objective. This study was aimed to study tissue distribution and tumor imaging potential of 68Ga-glycopeptide (GP) in tumor-bearing rodents by PET. Methods. GP was synthesized by conjugating glutamate peptide and chitosan. GP was labeled with 68Ga chloride for in vitro and in vivo studies. Computer outlined region of interest (counts per pixel) of the tumor and muscle (at the symmetric site) was used to determine tumor-to-muscle count density ratios. To ascertain the feasibility of 68Ga-GP in tumor imaging in large animals, PET/CT imaging of 68Ga-GP and 18F-FDG were conducted in New Zealand white rabbits bearing VX2 tumors. Standard uptake value of tumors were determined by PET up to 45 min. To determine blood clearance and half-life of 68Ga-GP, blood samples were collected from 10 seconds to 20 min. Results. Radiochemical purity of 68Ga-GP determined by instant thin-layer chromatography was >95%. Tumor uptake values (SUV) for 68Ga-GP and 18F-FDG in New Zealand white rabbits bearing VX2 tumors were 3.25 versus 7.04. PET images in tumor-bearing rats and rabbits confirmed that 68Ga-GP could assess tumor uptake. From blood clearance curve, the half-life of 68Ga-GP was 1.84 hr. Conclusion Our data indicate that it is feasible to use 68Ga-GP to assess tumor angiogenesis

Passive scalars, random flux, and chiral phase fluids

We study the two-dimensional localization problem for (i) a classical diffusing particle advected by a quenched random mean-zero vorticity field, and (ii) a quantum particle in a quenched random mean-zero magnetic field. Through a combination of numerical and analytic techniques we argue that both systems have extended eigenstates at a special point in the spectrum, $E_c$, where a sublattice decomposition obtains. In a neighborhood of this point, the Lyapunov exponents of the transfer-matrices acquire ratios characteristic of conformal invariance allowing an indirect determination of $1/r$ for the typical spatial decay of eigenstates.Comment: use revtex, two-column, 4 pages, 5 postscript figures, submitted to PR

Neonatal Glycemia and Neurodevelopmental Outcomes at 2 Years

From McKinlay, C. J. D., Alsweiler, J. M., Ansell, J. M., Anstice, N. S., Chase, J. G., Gamble, G. D., … Harding, J. E. (2015). Neonatal Glycemia and Neurodevelopmental Outcomes at 2 Years. New England Journal of Medicine, 373(16), 1507–1518. https://doi.org/10.1056/NEJMoa1504909 Copyright © 2015 Massachusetts Medical Society. Reprinted with permission.Neonatal hypoglycemia is a common and readily treatable risk factor for neurologic impairment in children. Although associations between prolonged symptomatic neonatal hypoglycemia and brain injury are well established,1 the effect of milder hypoglycemia on neurologic development is uncertain.2 Consequently, large numbers of newborns are screened and treated for low blood glucose concentrations, which involves heel-stick blood tests, substantial costs, and the possibility of iatrogenic harm. Under current guidelines,3 up to 30% of neonates are considered to be at risk for hypoglycemia, 15% receive a diagnosis of hypoglycemia, and approximately 10% require admission to a neonatal intensive care unit,4 costing an estimated $2.1 billion annually in the United States alone.5 Associated formula feeding and possible separation of mother and baby reduce breast-feeding rates,6 with potentially adverse effects on broader infant health and development. In addition, pain-induced stress in neonates, such as repeated heel sticks, may itself impair brain development.7 Thus, to determine appropriate glycemic thresholds for treatment, there have been repeated calls for studies of the effect of neonatal hypoglycemia on long-term development.2,8 We report the results of the Children with Hypoglycaemia and Their Later Development (CHYLD) study, a large prospective cohort study of term and late-preterm neonates born at risk for hypoglycemia. The study investigated the relation between the duration, frequency, and severity of low glucose concentrations in the neonatal period and neuropsychological development at 2 years.Supported by grants from the Eunice Kennedy Shriver National Institute of Child Health and Human Development (R01HD069622), the Health Research Council of New Zealand (10-399), and the Auckland Medical Research Foundation (1110009)

Rapamycin-Insensitive Up-Regulation of Adipocyte Phospholipase A2 in Tuberous Sclerosis and Lymphangioleiomyomatosis

Tuberous sclerosis syndrome (TSC) is an autosomal dominant tumor suppressor gene syndrome affecting multiple organs, including renal angiomyolipomas and pulmonary lymphangioleiomyomatosis (LAM). LAM is a female-predominant interstitial lung disease characterized by the progressive cyst formation and respiratory failure, which is also seen in sporadic patients without TSC. Mutations in TSC1 or TSC2 cause TSC, result in hyperactivation of mammalian target of rapamycin (mTOR), and are also seen in LAM cells in sporadic LAM. We recently reported that prostaglandin biosynthesis and cyclooxygenase-2 were deregulated in TSC and LAM. Phospholipase A2 (PLA2) is the rate-limiting enzyme that catalyzes the conversion of plasma membrane phospholipids into prostaglandins. In this study, we identified upregulation of adipocyte AdPLA2 (PLA2G16) in LAM nodule cells using publicly available expression data. We showed that the levels of AdPLA2 transcript and protein were higher in LAM lungs compared with control lungs. We then showed that TSC2 negatively regulates the expression of AdPLA2, and loss of TSC2 is associated with elevated production of prostaglandin E2 (PGE2) and prostacyclin (PGI2) in cell culture models. Mouse model studies also showed increased expression of AdPLA2 in xenograft tumors, estrogen-induced lung metastatic lesions of Tsc2 null leiomyoma-derived cells, and spontaneous renal cystadenomas from Tsc2+/− mice. Importantly, rapamycin treatment did not affect the expression of AdPLA2 and the production of PGE2 by TSC2-deficient mouse embryonic fibroblast (Tsc2−/−MEFs), rat uterine leiomyoma-derived ELT3 cells, and LAM patient-associated renal angiomyolipoma-derived “mesenchymal” cells. Furthermore, methyl arachidonyl fluorophosphate (MAFP), a potent irreversible PLA2 inhibitor, selectively suppressed the growth and induced apoptosis of TSC2-deficient LAM patient-derived cells relative to TSC2-addback cells. Our findings suggest that AdPLA2 plays an important role in promoting tumorigenesis and disease progression by modulating the production of prostaglandins and may serve as a potential therapeutic target in TSC and LAM