The utility of polarized heliospheric imaging for space weather monitoring.

A polarizing heliospheric imager is a critical next generation tool for space weather monitoring and prediction. Heliospheric imagers can track coronal mass ejections (CMEs) as they cross the solar system, using sunlight scattered by electrons in the CME. This tracking has been demonstrated to improve the forecasting of impact probability and arrival time for Earth-directed CMEs. Polarized imaging allows locating CMEs in three dimensions from a single vantage point. Recent advances in heliospheric imaging have demonstrated that a polarized imager is feasible with current component technology.Developing this technology to a high technology readiness level is critical for space weather relevant imaging from either a near-Earth or deep-space mission. In this primarily technical review, we developpreliminary hardware requirements for a space weather polarizing heliospheric imager system and outline possible ways to flight qualify and ultimately deploy the technology operationally on upcoming specific missions. We consider deployment as an instrument on NOAA's Deep Space Climate Observatory follow-on near the Sun-Earth L1 Lagrange point, as a stand-alone constellation of smallsats in low Earth orbit, or as an instrument located at the Sun-Earth L5 Lagrange point. The critical first step is the demonstration of the technology, in either a science or prototype operational mission context.

NFATc3 is required for chronic hypoxia-induced pulmonary hypertension in adult and neonatal mice.

Pulmonary hypertension occurs with prolonged exposure to chronic hypoxia in both adults and neonates. The Ca(2+)-dependent transcription factor, nuclear factor of activated T cells isoform c3 (NFATc3), has been implicated in chronic hypoxia-induced pulmonary arterial remodeling in adult mice. Therefore, we hypothesized that NFATc3 is required for chronic hypoxia-induced pulmonary hypertension in adult and neonatal mice. The aim of this study was to determine whether 1) NFATc3 mediates chronic hypoxia-induced increases in right ventricular systolic pressure in adult mice; 2) NFATc3 is activated in neonatal mice exposed to chronic hypoxia; and 3) NFATc3 is involved in chronic hypoxia-induced right ventricular hypertrophy and pulmonary vascular remodeling in neonatal mice. Adult mice were exposed to hypobaric hypoxia for 2, 7, and 21 days. Neonatal mouse pups were exposed for 7 days to hypobaric chronic hypoxia within 2 days after delivery. Hypoxia-induced increases in right ventricular systolic pressure were absent in NFATc3 knockout adult mice. In neonatal mice, chronic hypoxia caused NFAT activation in whole lung and nuclear accumulation of NFATc3 in both pulmonary vascular smooth muscle and endothelial cells. In addition, heterozygous NFATc3 neonates showed less right ventricular hypertrophy and pulmonary artery wall thickness in response to chronic hypoxia than did wild-type neonates. Our results suggest that NFATc3 mediates pulmonary hypertension and vascular remodeling in both adult and neonatal mice.

Genomic organization of the selectin family of leukocyte adhesion molecules on human and mouse chromosome 1.

A structurally and functionally related group of genes, lymph node homing receptor (LHR), granule membrane protein 140 (GMP-140), and endothelial leukocyte adhesion molecule 1 (ELAM-1) are shown to constitute a gene cluster on mouse and human chromosome 1. In situ hybridization mapped GMP-140 to human chromosome 1 bands 21-24 consistent with chromosomal localization of LHR. Gene linkage analysis in the mouse indicated that these genes and serum coagulation factor V (FV) all map to a region of distal mouse chromosome 1 that is syntenic with human chromosome 1, with no crossovers identified between these four genes in 428 meiotic events. Moreover, long range restriction site mapping demonstrated that these genes map to within 300 kb in both the human and mouse genomes. These data suggest that LHR, ELAM-1, and GMP-140 comprise an adhesion protein family, the selectins, that arose by multiple gene duplication events before divergence of mouse and human. Furthermore, the location of these genes on mouse and human chromosome 1 is consistent with a close evolutionary relationship to the complement receptor-related genes, which also are positioned on the same chromosomes in both species and with which these genes share a region of sequence homology. These data characterize the organization of a genomic region that may be critical for intercellular communication within the immune system.

Population expansion, clonal growth, and specific differentiation patterns in primary cultures of hepatocytes induced by HGF/SF, EGF and TGF alpha in a chemically defined (HGM) medium.

Mature adult parenchymal hepatocytes, typically of restricted capacity to proliferate in culture, can now enter into clonal growth under the influence of hepatocyte growth factor (scatter factor) (HGF/SF), epidermal growth factor (EGF), and transforming growth factor alpha (TGFalpha) in the presence of a new chemically defined medium (HGM). The expanding populations of hepatocytes lose expression of hepatocyte specific genes (albumin, cytochrome P450 IIB1), acquire expression of markers expressed by bile duct epithelium (cytokeratin 19), produce TGFalpha and acidic FGF and assume a very simplified morphologic phenotype by electron microscopy. A major change associated with this transition is the decrease in ratio between transcription factors C/EBPalpha and C/EBPbeta, as well as the emergence in the proliferating hepatocytes of transcription factors AP1, NFkappaB. The liver associated transcription factors HNFI, HNF3, and HNF4 are preserved throughout this process. After population expansion and clonal growth, the proliferating hepatocytes can return to mature hepatocyte phenotype in the presence of EHS gel (Matrigel). This includes complete restoration of electron microscopic structure and albumin expression. The hepatocyte cultures however can instead be induced to form acinar/ductular structures akin to bile ductules (in the presence of HGF/SF and type I collagen). These transformations affect the entire population of the hepatocytes and occur even when DNA synthesis is inhibited. Similar acinar/ductular structures are seen in embryonic liver when HGF/SF and its receptor are expressed at high levels. These findings strongly support the hypothesis that mature hepatocytes can function as or be a source of bipotential facultative hepatic stem cells (hepatoblasts). These studies also provide evidence for the growth factor and matrix signals that govern these complex phenotypic transitions of facultative stem cells which are crucial for recovery from acute and chronic liver injury.

Patellofemoral arthroplasty versus total knee arthroplasty for patients with patellofemoral osteoarthritis: equal function and satisfaction but higher revision rate for partial arthroplasty at a minimum eight years' follow-up.

AIMS: The primary aim of this study was to compare the knee-specific functional outcome of patellofemoral arthroplasty with total knee arthroplasty (TKA) in the management of patients with patellofemoral osteoarthritis. PATIENTS AND METHODS: A total of 54 consecutive Avon patellofemoral arthroplasties were identified and propensity-score-matched to a group of 54 patients undergoing a TKA with patellar resurfacing for patellofemoral osteoarthritis. The Oxford Knee Score (OKS), the 12-Item Short-Form Health Survey (SF-12), and patient satisfaction were collected at a mean follow up of 9.2 years (8 to 15). Survival was defined by revision or intention to revise. RESULTS: There was no significant difference in the mean OKS (p > 0.60) or SF-12 scores (p > 0.28) between the groups. There was a lower rate of satisfaction at the final follow-up for the TKA group (78% vs 87%) but this was not statistically significant (odds ratio 0.56, p = 0.21). Length of stay was significantly shorter (p = 0.008) for the Avon group (difference 1.8 days, 95% confidence interval (CI) 0.4 to 3.2). The ten-year survival for the Avon group was 92.3% (95% CI 87.1 to 97.5) and for the TKA group was 100% (95% CI 93.8 to 100). This difference was not statistically significant (log-rank test, p = 0.10). CONCLUSION: Patients undergoing an Avon patellofemoral arthroplasty have a shorter length of stay, and a functional outcome and rate of satisfaction that is equal to that of TKA. The benefits of the Avon arthroplasty need to be balanced against the increased rate of revision when compared with TKA.

Different isozymes of mouse 11 beta-hydroxylase produce mineralocorticoids and glucocorticoids.

We have isolated and characterized two isozymes of mouse steroid 11 beta-hydroxylase (11 beta-OHase), designated 11 beta-OHase and aldosterone synthase (AS). Physical mapping of overlapping cosmid and phage isolates defined two genes (designated Cyp11b-1 and Cyp11b-2 in the standard nomenclature for cytochrome P450 genes) that are oriented in the same direction and separated by approximately 8 kilobase pairs of DNA. The two genes are highly homologous in their coding regions, with 84% nucleotide identity and 86% predicted amino acid identity. In regions where the sequences of the rat 11 beta-OHase and AS genes diverged most widely, the mouse sequences also differed significantly, thereby identifying putative mouse 11 beta-OHase and AS genes. Both genes were mapped to chromosome 15 by analyzing restriction fragment length variations in a panel of DNA samples from an interspecific cross. To determine the functional properties of the 11 beta-OHase and AS proteins, we transfected COS-7 cells with plasmids that expressed the proteins encoded by the 11 beta-OHase and AS genes. When expressed in transfected COS-7 cells, the 11 beta-OHase protein converted deoxycorticosterone to corticosterone but did not produce aldosterone. Consistent with its postulated role in mineralocorticoid biosynthesis, the product of the AS gene efficiently synthesized aldosterone. We next studied the expression of these two isozymes in Y1 adrenocortical tumor cells and in the intact mouse adrenal gland. Although Y1 cells otherwise resemble zona fasciculata cells and express the 11 beta-OHase gene at high levels, transcripts encoded by the AS gene were detected at levels approximately 10-fold lower than the 11 beta-OHase transcripts.(ABSTRACT TRUNCATED AT 250 WORDS)

Circulating PIG-A mutant T lymphocytes in healthy adults and patients with bone marrow failure syndromes.

OBJECTIVE: Paroxysmal nocturnal hemoglobinuria (PNH) is a clonal hematological disorder with acquired PIG-A gene mutations and absent surface expression of proteins utilizing glycosylphosphatidylinositol (GPI) anchors. PNH often follows aplastic anemia, suggesting PIG-A mutant cells have relative dominance over normal hematopoietic cells. Somatic PIG-A mutations could arise after aplasia, or healthy persons could have rare PIG-A mutant cells that expand under selection pressure. METHODS: We developed an in vitro negative selection method to isolate GPI-deficient T lymphocytes using aerolysin, an Aeromonas toxin that binds GPI anchors and induces cell lysis. Peripheral blood mononuclear cells (PBMC) from normal adults and patients with PNH or other bone marrow failure syndromes were analyzed. RESULTS: From healthy adults, 166 T lymphocyte clones with deficient GPI-linked surface protein expression (CD55, CD59) were isolated. The mean mutant frequency (M(f)) of aerolysin-resistant clones was 17.8 +/- 13.8 per 10(6) PBMC, range 5.0-59.6 per 10(6) cells. Clones had a Class A complementation defect and distinct PIG-A mutations. Patients with PNH had elevated aerolysin-resistant M(f) values averaging 19 x 10(-2), a 10,000-fold difference. Two patients with Fanconi anemia and two others with mild aplastic anemia had M(f) values less than 15 x 10(-6), but two with recovering aplastic anemia had M(f) values of 20 x 10(-4), representing an intermediate value between normal persons and PNH patients. CONCLUSION: Identification of PIG-A mutant T lymphocytes in healthy adults suggests PNH could develop following intense negative selection of hematopoiesis, with clonal outgrowth of naturally occurring PIG-A mutant stem cells.

Neuronal and non-neuronal responses to nerve crush in a pulmonate snail, Melampus bidentatus.

Immunohistochemical and ultrastructural techniques were used to study sequelae of nerve injury in the pulmonate snail Melampus bidentatus. Either pedal or tentacle nerves were crushed, severing all axons, and recovery was monitored over 15 days. The axons regenerated from the segment attached to the soma, with no evidence of fusion of proximal and distal segments. The medium to large axons of central neurons, including those monitored with serotonin immunohistochemistry, grow distally across the path of smaller axons extending centrally from peripheral somata. The regions into which the growing axons projected were a focus of phagocytic activity. Cells previously labeled by PKH-26PCL, a fluorescent marker for phagocytic activity, were attracted to the crushed nerve within 6 h and were a consistent feature in the vicinity of the injury for at least 9 days, gradually extending their range as repair progressed in both directions from the crush. Repair proceeded within an intact sheath, and many sheath cells survived the crush, although the nuclear dye Hoechst 33258 revealed an initial distortion of their nuclei. The concentration of cells in the sheath in the crushed region increases after the crush, with the packing of nuclei peaking at 3 days and gradually returning to control conditions; this probably reflects migration of resident sheath cells. Cell division is rare in the sheath of intact nerves, but labeling with bromodeoxyuridine increases at the crush site between 4 and 9 days, indicating that cell replacement also occurs at the site.

Intermittent hypoxia-induced increases in reactive oxygen species activate NFATc3 increasing endothelin-1 vasoconstrictor reactivity.

Sleep apnea (SA), defined as intermittent respiratory arrest during sleep, is associated with increased incidence of hypertension, peripheral vascular disease, stroke, and sudden cardiac death. We have shown that intermittent hypoxia with CO2 supplementation (IH), a model for SA, increases blood pressure and circulating ET-1 levels, upregulates lung pre-pro ET-1 mRNA, increases vasoconstrictor reactivity to ET-1 in rat small mesenteric arteries (MA) and increases vascular reactive oxygen species (ROS). NFAT activity is increased in the aorta (AO) and MA of mice exposed to IH in an ET-1-dependent manner, and the genetic ablation of the isoform NFATc3 prevents IH-induced hypertension. We hypothesized that IH causes an increase in arterial ROS generation, which activates NFATc3 to increase vasoconstrictor reactivity to ET-1. In support of our hypothesis, we found that IH increases ROS in AO and MA. In vivo administration of the SOD mimetic tempol during IH exposure prevents IH-induced increases in NFAT activity in mouse MA and AO. We found that IH causes an NFATc3-dependent increase in vasoconstrictor reactivity to ET-1, accompanied by an increase in vessel wall [Ca²âº]. Our results indicate that IH exposure causes an increase in arterial ROS to activate NFATc3, which then increases vasoconstrictor reactivity and Ca²âº response to ET-1. These studies highlight a novel regulatory pathway, and demonstrate the potential clinical relevance of NFAT inhibition to prevent hypertension in SA patients.

Elevated numbers of gamma-delta (gamma delta+) T lymphocytes in children with immune thrombocytopenic purpura.

Immune thrombocytopenic purpura (ITP) in childhood is a heterogeneous clinical disorder characterized by immune-mediated platelet destruction. Although generally considered to involve autoreactive B lymphocytes which produce antiplatelet antibodies, there is increasing evidence that T lymphocytes also play an important role in this autoimmune process. We studied 11 children with acute ITP and 19 children with chronic ITP and observed elevated numbers of TCR gamma delta+ T lymphocytes in several patients. In the three children with the highest elevations (TCR gamma delta+/CD3+ percentage ranging from 37.8 to 48.1% at initial evaluation), the expanded cell population exclusively expressed the surface V delta 2/V gamma 9 heterodimer and had enhanced in vitro proliferation to mycobacterial extracts and IL-2. Analysis of the nucleotide sequences used by these TCR gamma delta+ cells demonstrated a diverse set of VDDJC gene rearrangements, indicating polyclonal expansion of cells reminiscent of a superantigen response. There was a close correlation between the number of TCR gamma delta+ T lymphocytes and the degree of thrombocytopenia in each patient. TCR gamma delta+ T lymphocytes may be important in the pathogenesis of immune-mediated platelet destruction in some children with ITP.

Phenotypic and clonal analysis of T lymphocytes in childhood immune thrombocytopenic purpura.

In an attempt to identify and characterize T-lymphocyte immunoregulatory abnormalities in immune thrombocytopenic purpura (ITP), we have performed phenotypic and clonal analysis on peripheral T lymphocytes from 23 children with ITP. Quantitation of lymphocyte subpopulations showed that children with acute ITP had higher numbers of CD45RA+ and lower numbers of CD45RO+ T cells than children with chronic ITP or controls, but these differences may be age related. Analysis of T-cell receptor variable beta gene usage identified 2 boys with chronic ITP and elevated numbers of V beta 8+ T cells. Eight T-cell clones were established (6 CD4+, 4B4+ helper-inducer lines and 2 CD8+ lines) that showed in vitro proliferation against allogeneic platelets. The addition of autologous antigen-presenting cells enhanced the proliferation of six clones, but not for two clones that coexpressed natural killer (NK) markers. Four of seven positive clones also had measurable interleukin (IL)-2 secretion following platelet stimulation, providing further evidence for T-cell reactivity. Our results provide the first evidence that patients with ITP may have platelet-reactive T lymphocytes identifiable at the clonal level, supporting the hypothesis that autoreactive peripheral T lymphocytes may mediate or participate in the pathogenesis of this disorder.

Clinical and imaging evaluation of the solitary pulmonary nodule.

Management of a solitary pulmonary nodule remains a common clinical problem. The main goal of management is to choose a diagnostic and therapeutic scheme that is appropriately matched to the patient's clinical risk of malignancy. Clinical risk can be estimated from consideration of data on the overall prevalence of malignancy in solitary pulmonary nodules in various populations, the size of the pulmonary nodule, the patient's age and the patient's history of smoking. Nodules that have not grown for at least two years and those that are calcified are usually benign and require no further work-up. Suspicious nodules require further evaluation. The approach for patients at low clinical risk for malignancy may be clinical and radiographic observation, while that for patients at moderate to high risk for malignancy may be needle biopsy or thoracotomy. Whenever possible, the patient should be encouraged to participate in the decision-making process concerning the management of this clinical problem.

Mapping of recombinant retrovirus integration sites that cause expression of the viral genome in murine embryonal carcinoma cells.

Murine embryonal carcinoma (EC) cells do not normally express Moloney murine leukemia virus genes. Earlier, rare EC cell lines were isolated that expressed proviral neomycin resistance (neo) gene. This expression was dependent on cellular enhancer or promoter sequences that flank the proviral integration site. Four such integration sites, designated as Mint (for Moloney murine leukemia virus integration and expression sites in EC cells), have been mapped on mouse chromosomes. Minta, Mintb, Mintc and Mintd are unlinked and mapped on different chromosomes (Chr), Chr 10, Chr 1, Chr 5 and the X Chr, respectively. None of these loci appear to be linked to any known Mo-MuLV proviral integration sites previously mapped. These enhancer and promoter loci may represent a new set of genes active in undifferentiated embryonic cells.

Comparison of linkage maps of mouse chromosome 12 derived from laboratory strain intraspecific and Mus spretus interspecific backcrosses.

Progeny from an interspecific backcross between laboratory mice and Mus spretus were typed for inheritance of eight genetic markers on chromosome 12. Marker order determined by segregation analyses of 115 meiotic events was in good agreement with that determined previously using intraspecific laboratory strain backcrosses. Two additional markers, D12Nyu5 and Lamb-1, previously not ordered, were located in the middle of the interval between D12Nyu12 and D12Nyu1. Marker spacing was reduced in the interspecific cross relative to that observed in intraspecific crosses. Furthermore, the interspecific cross was characterized by marked deviation from 1:1 segregation in the recombinant chromosomes and very strong positive interference. These data suggest that comparisons of different mouse crosses may facilitate the understanding of underlying mechanisms that govern recombination events in complex genomes.

Congenital pulmonary venolobar syndrome revisited.

The term "congenital pulmonary venolobar syndrome" (CPVS) encompasses a number of congenital abnormalities of the thorax that often occur in combination. Major components of CPVS include hypogenetic lung, partial anomalous pulmonary venous return (this and the former are two of the most constantly occurring components), absence of a pulmonary artery, pulmonary sequestration, systemic arterialization of the lung, absence of the inferior vena cava, and accessory diaphragm. Minor components of CPVS include tracheal trifurcation, eventration and partial absence of the diaphragm, phrenic cyst, horseshoe lung, esophageal and gastric lung, anomalous superior vena cava, and absence of the left pericardium. Most patients with CPVS have no symptoms and require no therapy; however, surgical intervention is often necessary in infants with severe symptoms. The authors review the imaging findings in 29 patients with CPVS and review the literature concerning the diagnosis and management of this complex syndrome in order to improve the understanding of CPVS among radiologists and clinicians.

Mutations within the Piga gene in patients with paroxysmal nocturnal hemoglobinuria.

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired clonal hematologic disorder with multiple and varied clinical manifestations. The biochemical defect in PNH resides in the incomplete enzymatic assembly of glycosylphosphatidylinositol (GPI) anchors used for surface protein attachment. In all patients tested thus far, the defect is at the level of N-acetylglucosamine attachment to phosphatidylinositol (complementation class A defect). A human cDNA, Piga, that repairs cell lines with the class A defect has been recently cloned, making Piga a candidate gene for PNH. In the current study, using highly purified GPI-deficient granulocytes, we have performed Northern blot and reverse transcriptase polymerase chain reaction (RT-PCR) analysis of Piga in four patients with PNH. In each case, we have identified a mutation in the Piga coding sequence: three frameshift mutations were found, and a single nucleotide substitution (missense) mutation was identified. Our results provide convincing evidence that alterations in the Piga gene are responsible for PNH.

Mapping of the mouse Rar loci encoding retinoic acid receptors RAR alpha, RAR beta and RAR gamma.

Nuclear retinoic acid receptors RAR alpha, RAR beta and RAR gamma are transcription factors that bind all-trans retinoic acid as their ligand and mediate its action by activating particular set of genes that contain retinoic acid responsive elements in their promoter-enhancers. We have mapped genetic loci for these genes using restriction fragment length variants (RFLVs) in interspecific backcross mice. None of the Rar loci cosegregated with each other or with the new subclass of retinoid receptors, Rxr loci. Rara mapped to mChr 11, Rarb mapped to mChr 14, and Rarg mapped to mChr 15. The results are consistent with the previous reports and the human data in terms of syntenic homology between mouse and human chromosomes.

Comparative analysis of mitogenic and morphogenic effects of HGF and EGF on rat and human hepatocytes maintained in collagen gels.

Hepatocytes maintained in collagen gels remain differentiated for prolonged periods of time compared to cells maintained on conventional cultures. Previous studies with other culture systems in which chemical supplements or substratum modifications enhanced hepatocyte differentiation showed that in all of these systems hepatocytes do not respond to mitogens. In this study it is shown that hepatocytes maintained between two layers of collagen gels respond to mitogens HGF (also known as scatter factor (HGF/SF)) and epidermal growth factor (EGF). Cell density did not affect the responsiveness to mitogens as in conventional cultures. In addition both mitogens (HGF more pronounced) induce characteristic morphogenic changes in which hepatocytes form processes and join in formation of cords. Hepatocytes respond to mitogens for up to 6 days in culture at which point they become refractory to further mitogenic stimulation. This occurs despite electron microscopic evidence that these cells are fully viable when they become refractory to mitogenesis. The refractory state is not modified by substitution of one growth factor for the other or by addition of growth factors at different times. Hepatocytes in the refractory state become again responsive to mitogens when the collagen gels are dispersed by collagenase and the cells are replated on conventional substrates.

A 6000 kb segment of chromosome 1 is conserved in human and mouse.

A murine linkage map generated from analyses of 428 meiotic events in an interspecific cross and pulsed field gel electrophoresis allowed examination of the genomic organization of a 6000 kb segment of mouse and human chromosome 1. Analysis of five genes within this syntenic segment of both species revealed striking conservation of gene order, intergenic distance and, to a lesser extent, CpG dinucleotides. In the mouse, meiotic crossover events were not evenly distributed; a hot spot for meiotic recombination was coincident with a CpG-island. These studies provide a practical approach to aid physical mapping of the human genome and a model for determining the molecular principles that govern meiotic recombination. In addition, these findings demonstrate profound conservation of genomic organization over mammalian evolution.