Intermittent hypoxia during recovery from neonatal hyperoxic lung injury causes long-term impairment of alveolar development: A new rat model of BPD.

Bronchopulmonary dysplasia (BPD) is a chronic lung injury characterized by impaired alveologenesis that may persist into adulthood. Rat models of BPD using varying degrees of hyperoxia to produce injury either cause early mortality or spontaneously recover following removal of the inciting stimulus, thus limiting clinical relevance. We sought to refine an established rat model induced by exposure to 60% O2 from birth by following hyperoxia with intermittent hypoxia (IH). Rats exposed from birth to air or 60% O2 until day 14 were recovered in air with or without IH (FIO2 = 0.10 for 10 min every 6 h) until day 28 Animals exposed to 60% O2 and recovered in air had no evidence of abnormal lung morphology on day 28 or at 10-12 wk. In contrast, 60% O2-exposed animals recovered in IH had persistently increased mean chord length, more dysmorphic septal crests, and fewer peripheral arteries. Recovery in IH also increased pulmonary vascular resistance, Fulton index, and arterial wall thickness. IH-mediated abnormalities in lung structure (but not pulmonary hypertension) persisted when reexamined at 10-12 wk, accompanied by increased pulmonary vascular reactivity and decreased exercise tolerance. Increased mean chord length secondary to IH was prevented by treatment with a peroxynitrite decomposition catalyst [5,10,15,20-Tetrakis(4-sulfonatophenyl)-21H,23H-porphyrin iron (III) chloride, 30 mg/kg/day, days 14-28], an effect accompanied by fewer inflammatory cells. We conclude that IH during recovery from hyperoxia-induced injury prevents recovery of alveologenesis and leads to changes in lung and pulmonary vascular function lasting into adulthood, thus more closely mimicking contemporary BPD.

Simvastatin prevents and reverses chronic pulmonary hypertension in newborn rats via pleiotropic inhibition of RhoA signaling.

Chronic neonatal pulmonary hypertension (PHT) frequently results in early death. Systemically administered Rho-kinase (ROCK) inhibitors prevent and reverse chronic PHT in neonatal rats, but at the cost of severe adverse effects, including systemic hypotension and growth restriction. Simvastatin has pleiotropic inhibitory effects on isoprenoid intermediates that may limit activity of RhoA, which signals upstream of ROCK. We therefore hypothesized that statin treatment would safely limit pulmonary vascular RhoA activity and prevent and reverse experimental chronic neonatal PHT via downstream inhibitory effects on pathological ROCK activity. Sprague-Dawley rats in normoxia (room air) or moderate normobaric hypoxia (13% O2) received simvastatin (2 mg·kg-1·day-1 ip) or vehicle from postnatal days 1-14 (prevention protocol) or from days 14-21 (rescue protocol). Chronic hypoxia increased RhoA and ROCK activity in lung tissue. Simvastatin reduced lung content of the isoprenoid intermediate farnesyl pyrophosphate and decreased RhoA/ROCK signaling in the hypoxia-exposed lung. Preventive or rescue treatment of chronic hypoxia-exposed animals with simvastatin decreased pulmonary vascular resistance, right ventricular hypertrophy, and pulmonary arterial remodeling. Preventive simvastatin treatment improved weight gain, did not lower systemic blood pressure, and did not cause apparent toxic effects on skeletal muscle, liver or brain. Rescue therapy with simvastatin improved exercise capacity. We conclude that simvastatin limits RhoA/ROCK activity in the chronic hypoxia-exposed lung, thus preventing or ameliorating hemodynamic and structural markers of chronic PHT and improving long-term outcome, without causing adverse effects.

Leukotriene B4 mediates macrophage influx and pulmonary hypertension in bleomycin-induced chronic neonatal lung injury.

Systemically-administered bleomycin causes inflammation, arrested lung growth, and pulmonary hypertension (PHT) in the neonatal rat, similar to human infants with severe bronchopulmonary dysplasia (BPD). Leukotrienes (LTs) are inflammatory lipid mediators produced by multiple cell types in the lung. The major LTs, LTB4 and cysteinyl LTs, are suggested to contribute to BPD, but their specific roles remain largely unexplored in experimental models. We hypothesized that LTs are increased in bleomycin-induced BPD-like injury, and that inhibition of LT production would prevent inflammatory cell influx and thereby ameliorate lung injury. Rat pups were exposed to bleomycin (1 mg·kg(-1)·day(-1) ip) or vehicle (control) from postnatal days 1-14 and were treated with either zileuton (5-lipoxygenase inhibitor), montelukast (cysteinyl LT1 receptor antagonist), or SC57461A (LTA4 hydrolase inhibitor) 10 mg·kg(-1)·day(-1) ip. Bleomycin led to increased lung content of LTB4, but not cysteinyl LTs. Bleomycin-induced increases in tissue neutrophils and macrophages and lung contents of LTB4 and tumor necrosis factor-α were all prevented by treatment with zileuton. Treatment with zileuton or SC57461A also prevented the hemodynamic and structural markers of chronic PHT, including raised pulmonary vascular resistance, increased Fulton index, and arterial wall remodeling. However, neither treatment prevented impaired alveolarization or vascular hypoplasia secondary to bleomycin. Treatment with montelukast had no effect on macrophage influx, PHT, or on abnormal lung structure. We conclude that LTB4 plays a crucial role in lung inflammation and PHT in experimental BPD. Agents targeting LTB4 or LTB4-mediated signaling may have utility in infants at risk of developing BPD-associated PHT.

The degree of astrocyte activation in multiple system atrophy is inversely proportional to the distance to α-synuclein inclusions.

Multiple system atrophy (MSA) exhibits widespread astrogliosis together with α-synuclein (α-syn) glial cytoplasmic inclusions (GCIs) in mature oligodendrocytes. We quantified astrocyte activation by morphometric analysis of MSA cases, and investigated the correlation to GCI proximity. Using Imaris software, we obtained "skinned" three-dimensional models of GFAP-positive astrocytes in MSA and control tissue (n=75) from confocal z-stacks and measured the astrocyte process length and thickness and radial distance to the GCI. Astrocytes proximal to GCI-containing oligodendrocytes (r<25µm) had significantly (p, 0.05) longer and thicker processes characteristic of activation than distal astrocytes (r>25µm), with a reciprocal linear correlation (m, 90µm(2)) between mean process length and radial distance to the nearest GCI (R(2), 0.7). In primary cell culture studies, α-syn addition caused ERK-dependent activation of rat astrocytes and perinuclear α-syn inclusions in mature (MOSP-positive) rat oligodendrocytes. Activated astrocytes were also observed in close proximity to α-syn deposits in a unilateral rotenone-lesion mouse model. Moreover, unilateral injection of MSA tissue-derived α-syn into the mouse medial forebrain bundle resulted in widespread neuroinflammation in the α-syn-injected, but not sham-injected hemisphere. Taken together, our data suggests that the action of localized concentrations of α-syn may underlie both astrocyte and oligodendrocyte MSA pathological features.

The UCSC Genome Browser database: extensions and updates 2011.

The University of California Santa Cruz Genome Browser (http://genome.ucsc.edu) offers online public access to a growing database of genomic sequence and annotations for a wide variety of organisms. The Browser is an integrated tool set for visualizing, comparing, analyzing and sharing both publicly available and user-generated genomic data sets. In the past year, the local database has been updated with four new species assemblies, and we anticipate another four will be released by the end of 2011. Further, a large number of annotation tracks have been either added, updated by contributors, or remapped to the latest human reference genome. Among these are new phenotype and disease annotations, UCSC genes, and a major dbSNP update, which required new visualization methods. Growing beyond the local database, this year we have introduced 'track data hubs', which allow the Genome Browser to provide access to remotely located sets of annotations. This feature is designed to significantly extend the number and variety of annotation tracks that are publicly available for visualization and analysis from within our site. We have also introduced several usability features including track search and a context-sensitive menu of options available with a right-click anywhere on the Browser's image.

Associations between paraspinal muscle characteristics and spinal curvature in conservatively treated adolescent idiopathic scoliosis: a systematic review.

BACKGROUND CONTEXT: Children with adolescent idiopathic scoliosis (AIS) may show asymmetrical paraspinal muscle characteristics. PURPOSE: To summarize the evidence regarding: (1) the associations between various paraspinal muscle characteristics and spinal curvature; (2) whether paraspinal muscle properties significantly differed between children with and without AIS; and (3) whether baseline paraspinal muscle characteristics predicted curve progression. STUDY DESIGN/SETTING: Systematic literature review. METHODS: Five databases (CINAHL, Academic Search Premier, MEDLINE, Scopus, and PubMed) were searched from inception to May 2022. This protocol was registered in the PROSPERO database of systematic reviews CRD 42020171263. The Critical appraisal skills program, the Appraisal Tool for Cross-Sectional Studies and Quality In Prognosis Studies tool were used to evaluate the risk of bias of the included studies. The strength of evidence of each identified association was determined by the Grading of Recommendations Assessment, Development, and Evaluation System (GRADE). RESULTS: Of 1,530 identified citations, four cohort, 17 cross-sectional, and 23 case-control studies including 31 with low, nine with moderate and four with high risk of bias were included. Low to very low-strength evidence supported that the convex side of the curve had more type I muscle fibers, higher muscle volume and paraspinal muscle activity, while the concavity had more intramuscular fatty infiltration. Very low-strength evidence substantiated greater side-to-side surface electromyography signals during left trunk bending in prone lying, standing, and standing with perturbation between people with and without AIS. Also, low to very low-strength evidence supported that a larger side-to-side surface electromyography ratio at the lower end vertebra predicted curve progression. CONCLUSIONS: Our review highlights that paraspinal muscles on the concavity of the curve demonstrate consistent changes (ie, altered muscle-related gene expression, muscle atrophy, increased fatty infiltration, reduced type I fibers, and reduced muscle activity), which may be the cause or consequence.

Hong Kong's new wave of migration: socio-political factors of individuals' intention to emigrate.

With a recent surge in the outward movement of the population, a new wave of emigration has been suggested to have started in Hong Kong. It is speculated that recent socio-political changes in Hong Kong may have contributed to this phenomenon. Therefore, five socio-political variables-mobility, sense of place, trust and confidence in the law and the legal system, global citizenship, and perception of inequality-are employed in this study as proposed determinants to investigate the intention of Hong Kong residents to migrate to mainland China and to other international destinations. A random telephone questionnaire survey representative of the local population was conducted, with a total of 801 valid samples collected. Stepwise multiple regression analysis was carried out. The results showed that all five proposed socio-political variables successfully predicted people's migration intention to mainland China and to foreign countries, with important variations between the two choices. Our results carry strong implications for understanding people's concerns behind their intention to emigrate. Further, our findings present a challenge for Hong Kong; society may gradually be failing to accommodate individuals with diverse perceptions and values, particularly in terms of trust and confidence in the law and the legal system, and individuals' sense of global citizenship.

mTOR-Notch3 signaling mediates pulmonary hypertension in hypoxia-exposed neonatal rats independent of changes in autophagy.

BACKGROUND/AIM: Mammalian target of rapamycin (mTOR) is a pivotal regulator of cell proliferation, survival, and autophagy. Autophagy is increased in adult experimental chronic pulmonary hypertension (PHT), but its contributory role to pulmonary vascular disease remains uncertain and has yet to be explored in the neonatal animal. Notch is a major pro-proliferative pathway activated by mTOR. A direct relationship between autophagy and Notch signaling has not been previously explored. Our aim was to examine changes in mTOR-, Notch-, and autophagy-related pathways and the therapeutic effects of autophagy modulators in experimental chronic neonatal PHT secondary to chronic hypoxia. METHODS: Rat pups were exposed to normoxia or hypoxia (13% O2 ) from postnatal days 1-21, while receiving treatment with temsirolimus (mTOR inhibitor), DAPT (Notch inhibitor), or chloroquine (inhibitor of autophagic flux). RESULTS: Exposure to hypoxia up-regulated autophagy and Notch3 signaling markers in lung, pulmonary artery (PA), and PA-derived smooth muscle cells (SMCs). Temsirolimus prevented chronic PHT and attenuated PA and SMC signaling secondary to hypoxia. These effects were replicated by DAPT. mTOR or Notch inhibition also down-regulated smooth muscle content of platelet-derived growth factor ß-receptor, a known contributor to vascular remodeling. In contrast, chloroquine had no modifying effects on markers of chronic PHT. Knockdown of Beclin-1 in SMCs had no effect on hypoxia-stimulated Notch3 signaling. CONCLUSIONS: mTOR-Notch3 signaling plays a critical role in experimental chronic neonatal PHT. Inhibition of autophagy did not suppress Notch signaling and had no effect on markers of chronic PHT.

Direct and/or Indirect Roles for SUMO in Modulating Alpha-Synuclein Toxicity.

α-Synuclein inclusion bodies are a pathological hallmark of several neurodegenerative diseases, including Parkinson's disease, and contain aggregated α-synuclein and a variety of recruited factors, including protein chaperones, proteasome components, ubiquitin and the small ubiquitin-like modifier, SUMO-1. Cell culture and animal model studies suggest that misfolded, aggregated α-synuclein is actively translocated via the cytoskeletal system to a region of the cell where other factors that help to lessen the toxic effects can also be recruited. SUMO-1 covalently conjugates to various intracellular target proteins in a way analogous to ubiquitination to alter cellular distribution, function and metabolism and also plays an important role in a growing list of cellular pathways, including exosome secretion and apoptosis. Furthermore, SUMO-1 modified proteins have recently been linked to cell stress responses, such as oxidative stress response and heat shock response, with increased SUMOylation being neuroprotective in some cases. Several recent studies have linked SUMOylation to the ubiquitin-proteasome system, while other evidence implicates the lysosomal pathway. Other reports depict a direct mechanism whereby sumoylation reduced the aggregation tendency of α-synuclein, and reduced the toxicity. However, the precise role of SUMO-1 in neurodegeneration remains unclear. In this review, we explore the potential direct or indirect role(s) of SUMO-1 in the cellular response to misfolded α-synuclein in neurodegenerative disorders.

Feasibility study of robotic hypofractionated lung radiotherapy by individualized internal target volume and XSight Spine Tracking: a preliminary dosimetric evaluation.

AIM: To investigate the dosimetric impacts of lung tumor motion in robotic hypofractionated radiotherapy for lung cancers delivered through continuous tracking of the vertebrae by the XSight Spine Tracking (XST) mode of the CyberKnife. MATERIALS AND METHODS: Four-dimensional computed tomography (4DCT) scans of a dynamic thorax phantom were acquired. Three motion patterns (one-dimensional and three-dimensional) of different range were investigated. Monte Carlo dose distributions were generated with 4DCT-derived internal target volume (ITV) with a treatment-specific setup margin for 12.6 Gy/3 fractions. Six-dimensional error correction was performed by kV stereoscopic imaging of the phantom's spine. Dosimetric effects of intrafractional tumor motion were assessed with Gafchromic films (Ashland Inc, Wayne, NJ, USA) according to 1) the percent measurement dose points having doses above the prescribed (P (> Dpres)), mean (P (> Dm)), and minimum (P (> Dmin)) ITV doses, and 2) the coefficient of variation (CV). RESULTS: All plans attained the prescription dose after three fractions despite marked temporal dose variations. The value of P (> Dpres) was 100% after three fractions for all plans, but could be smaller (~96%) for one fraction. The values of P (> Dmin) and P (> Dm) varied drastically interfractionally (25%-2%), and could be close to 0% after three fractions. The average CV ranged from 2.8% to 7.0%. Correlations with collimator size were significant for P (> Dmin) and P (> Dm) (P < 0.05) but not P (> Dpres) (P > 0.05). CONCLUSIONS: Treating lung tumors with CyberKnife through continuous tracking of the vertebrae should not be attempted without effective means to reduce the amplitude and variability of target motion because temporal dose variations owing to the intrafractional target motion can be significant.

Effects of a novel long noncoding RNA, lncUSMycN, on N-Myc expression and neuroblastoma progression.

BACKGROUND: Patients with neuroblastoma due to the amplification of a 130-kb genomic DNA region containing the MYCN oncogene have poor prognoses. METHODS: Bioinformatics data were used to discover a novel long noncoding RNA, lncUSMycN, at the 130-kb amplicon. RNA-protein pull-down assays were used to identify proteins bound to lncUSMycN RNA. Kaplan-Meier survival analysis, multivariable Cox regression, and two-sided log-rank test were used to examine the prognostic value of lncUSMycN and NonO expression in three cohorts of neuroblastoma patients (n = 47, 88, and 476, respectively). Neuroblastoma-bearing mice were treated with antisense oligonucleotides targeting lncUSMycN (n = 12) or mismatch sequence (n = 13), and results were analyzed by multiple comparison two-way analysis of variance. All statistical tests were two-sided. RESULTS: Bioinformatics data predicted lncUSMycN gene and RNA, and reverse-transcription polymerase chain reaction confirmed its three exons and two introns. The lncUSMycN gene was coamplified with MYCN in 88 of 341 human neuroblastoma tissues. lncUSMycN RNA bound to the RNA-binding protein NonO, leading to N-Myc RNA upregulation and neuroblastoma cell proliferation. High levels of lncUSMycN and NonO expression in human neuroblastoma tissues independently predicted poor patient prognoses (lncUSMycN: hazard ratio [HR] = 1.87, 95% confidence interval [CI] = 1.06 to 3.28, P = .03; NonO: HR = 2.48, 95% CI = 1.34 to 4.57, P = .004). Treatment with antisense oligonucleotides targeting lncUSMycN in neuroblastoma-bearing mice statistically significantly hindered tumor progression (P < .001). CONCLUSIONS: Our data demonstrate the important roles of lncUSMycN and NonO in regulating N-Myc expression and neuroblastoma oncogenesis and provide the first evidence that amplification of long noncoding RNA genes can contribute to tumorigenesis.

Potassium depolarization and raised calcium induces α-synuclein aggregates.

α-Synuclein is the key aggregating protein in Parkinson's disease (PD), which is characterized by cytoplasmic protein inclusion bodies, termed Lewy bodies, thought to increase longevity of the host neuron by sequestering toxic soluble α-synuclein oligomers. Previous post-mortem studies have shown relative sparing of neurons in PD that are positive for the Ca(2+) buffering protein, calbindin, and recent cell culture and in vitro studies have shown that α-synuclein aggregation can be induced by Ca(2+). We hypothesized that depolarization with potassium resulting in raised Ca(2+) in a PD cell culture model will lead to the formation of α-synuclein protein aggregates and that the intracellular Ca(2+) buffer, BAPTA-AM, may suppress their formation. Live cell fluorescence microscopy was performed to monitor changes in intracellular free calcium in HEK293T, SH-SY5Y neuroblastoma or stably transfected HEK293T/α-synuclein cells. Raised intracellular free Ca(2+) was consistently observed in cells treated with KCl, but not controls. Immunohistochemistry analysis on cells 48-72 h after K(+) treatment revealed two subsets of cells with either large (>2 µm), perinuclear α-synuclein aggregates or multiple smaller (<2 µm), cytoplasmic accumulations. Cells pre-treated with varying concentrations of trimethadione (TMO), a calcium channel blocker, showed suppression of the Ca(2+) transient following KCl treatment and no α-synuclein aggregates at TMO concentrations >5 µM. Quantitative analysis revealed a significant increase in the number of cells bearing α-synuclein cytoplasmic inclusions in both HEK293T/α-synuclein and SHSY-5Y cells when transient intracellular raised Ca(2+) was induced (p = 0.001). BAPTA-AM pre-loading significantly suppressed α-synuclein aggregates (p = 0.001) and the intracellular free Ca(2+) transient. This study indicates that raised intracellular Ca(2+) mediated by K(+) depolarization can lead to α-synuclein aggregation.

SUMO-1 is associated with a subset of lysosomes in glial protein aggregate diseases.

Oligodendroglial inclusion bodies characterize a subset of neurodegenerative diseases. Multiple system atrophy (MSA) is characterized by α-synuclein glial cytoplasmic inclusions and progressive supranuclear palsy (PSP) is associated with glial tau inclusions. The ubiquitin homologue, SUMO-1, has been identified in inclusion bodies in MSA, located in discrete sub-domains in α-synuclein-positive inclusions. We investigated SUMO-1 associated with oligodendroglial inclusion bodies in brain tissue from MSA and PSP and in glial cell models. We examined MSA and PSP cases and compared to age-matched normal controls. Fluorescence immunohistochemistry revealed frequent SUMO-1 sub-domains within and surrounding inclusions bodies in both diseases and showed punctate co-localization of SUMO-1 and the lysosomal marker, cathepsin D, in affected brain regions. Cell counting data revealed that 70-75 % of lysosomes in inclusion body-positive oligodendrocytes were SUMO-1-positive consistently across MSA and PSP cases, compared to 20 % in neighbouring inclusion body negative oligodendrocytes and 10 % in normal brain tissue. Hsp90 co-localized with some SUMO-1 puncta. We examined the SUMO-1 status of lysosomes in 1321N1 human glioma cells over-expressing α-synuclein and in immortalized rat oligodendrocyte cells over-expressing the four repeat form of tau following treatment with the proteasome inhibitor, MG132. We also transfected 1321N1 cells with the inherently aggregation-prone huntingtin exon 1 mutant, HttQ74-GFP. Each cell model showed the association of SUMO-1-positive lysosomes around focal cytoplasmic accumulations of α-synuclein, tau or HttQ74-GFP, respectively. Association of SUMO-1 with lysosomes was also detected in glial cells bearing α-synuclein aggregates in a rotenone-lesioned rat model. SUMO-1 labelling of lysosomes showed a major increase between 24 and 48 h post-incubation of 1321N1 cells with MG132 resulting in an increase in a 90 kDa SUMO-1-positive band that was immunopositive for Hsp90 and immunoprecipitated with an anti-SUMO-1 antibody. That SUMO-1 co-localizes with a subset of lysosomes in neurodegenerative diseases with glial protein aggregates and in glial cell culture models of protein aggregation suggests a role for SUMO-1 in lysosome function.

Imaging of the mastoid, middle ear, and internal auditory canal after surgery: what every radiologist should know.

Interpreting CT or MR imaging examinations performed on patients with a history of middle ear, mastoid, or neurotologic surgery can be challenging. This is greatly simplified by knowing the surgical procedures used and the expected postoperative appearance. These are reviewed and illustrated in this article. Knowing the normal postoperative appearance is the key to recognizing signs of recurrent disease.