The rise and emergence of untwisted toroidal flux ropes on the sun

Magnetic flux ropes (MFRs) rising buoyantly through the Sun's convection zone are thought to be subject to viscous forces preventing them from rising coherently. Numerous studies have suggested that MFRs require a minimum twist in order to remain coherent during their rise. Furthermore, even MFRs that get to the photosphere may be unable to successfully emerge into the corona unless they are at least moderately twisted, since the magnetic pressure gradient needs to overcome the weight of the photospheric plasma. To date, however, no lower limit has been placed on the critical minimum twist required for an MFR to rise coherently through the convection zone or emerge through the photosphere. In this paper, we simulate an untwisted toroidal MFR that is able to rise from the convection zone and emerge through the photosphere as an active region that resembles those observed on the Sun. We show that untwisted MFRs can remain coherent during their rise and then pile up near the photosphere, triggering undular instability, allowing the MFR to emerge through the photosphere. We propose that the toroidal geometry of our MFR is critical for its coherent rise. Upon emergence, a pair of lobes rises into the corona. The two lobes then interact and reconnect, resulting in a localized high speed jet. The resulting photospheric magnetogram displays the characteristic salt-and-pepper structure often seen in observations. Our major result is that MFRs need not be twisted to rise coherently through the convection zone and emerge through the photosphere. © 2021. The American Astronomical Society. All rights reserved

Primary chronic cold agglutinin disease: An update on pathogenesis, clinical features and therapy

Chronic cold agglutinin disease (CAD) is a subgroup of autoimmune hemolytic anemia. Primary CAD has traditionally been defined by the absence of any underlying or associated disease. The results of therapy with corticosteroids, alkylating agents and interferon-a have been poor. Cold reactive immunoglobulins against erythrocyte surface antigens are essential to pathogenesis of CAD. These cold agglutinins are monoclonal, usually IgMκ auto antibodies with heavy chain variable regions encoded by the VH4-34 gene segment. By flowcytometric and immunohistochemical assessments, a monoclonal CD20+κ+B-lymphocyte population has been demonstrated in the bone marrow of 90% of the patients, and lymphoplasmacytic lymphoma is a frequent finding. Novel attempts at treatment for primary CAD have mostly been directed against the clonal B-lymphocytes. Phase 2 studies have shown that therapy with the chimeric anti-CD20 antibody rituximab produced partial response rates of more than 50% and occasional complete responses. Median response duration, however, was only 11 months. In this review, we discuss the clinical and pathogenetic features of primary CAD, emphasizing the more recent data on its close association with clonal lymphoproliferative bone marrow disorders and implications for therapy. We also review the management and outline some perspectives on new therapy modalities

Metastatic MTLn3 and non-metastatic MTC adenocarcinoma cells can be differentiated by Pseudomonas aeruginosa

Cancer patients are known to be highly susceptible to Pseudomonas aeruginosa (Pa) infection, but it remains unknown whether alterations at the tumor cell level can contribute to infection. This study explored how cellular changes associated with tumor metastasis influence Pa infection using highly metastatic MTLn3 cells and non-metastatic MTC cells as cell culture models. MTLn3 cells were found to be more sensitive to Pa infection than MTC cells based on increased translocation of the type III secretion effector, ExoS, into MTLn3 cells. Subsequent studies found that higher levels of ExoS translocation into MTLn3 cells related to Pa entry and secretion of ExoS within MTLn3 cells, rather than conventional ExoS translocation by external Pa. ExoS includes both Rho GTPase activating protein (GAP) and ADP-ribosyltransferase (ADPRT) enzyme activities, and differences in MTLn3 and MTC cell responsiveness to ExoS were found to relate to the targeting of ExoS-GAP activity to Rho GTPases. MTLn3 cell migration is mediated by RhoA activation at the leading edge, and inhibition of RhoA activity decreased ExoS translocation into MTLn3 cells to levels similar to those of MTC cells. The ability of Pa to be internalized and transfer ExoS more efficiently in association with Rho activation during tumor metastasis confirms that alterations in cell migration that occur in conjunction with tumor metastasis contribute to Pa infection in cancer patients. This study also raises the possibility that Pa might serve as a biological tool for dissecting or detecting cellular alterations associated with tumor metastasis

A 1D RCE study of factors affecting the tropical tropopause layer and surface climate

There are discrepancies between global climate models regarding the evolution of the tropical tropopause layer (TTL) and also whether changes in ozone impact the surface under climate change. We use a 1D clear-sky radiative–convective equilibrium model to determine how a variety of factors can affect the TTL and how they influence surface climate. We develop a new method of convective adjustment, which relaxes the temperature profile toward the moist adiabat and allows for cooling above the level of neutral buoyancy. The TTL temperatures in our model are sensitive to CO2 concentration, ozone profile, the method of convective adjustment, and the upwelling velocity, which is used to calculate a dynamical cooling rate in the stratosphere. Moreover, the temperature response of the TTL to changes in each of the above factors sometimes depends on the others. The surface temperature response to changes in ozone and upwelling at and above the TTL is also strongly amplified by both stratospheric and tropospheric water vapor changes. With all these influencing factors, it is not surprising that global models disagree with regard to TTL structure and evolution and the influence of ozone changes on surface temperatures. On the other hand, the effect of doubling CO2 on the surface, including just radiative, water vapor, and lapse-rate feedbacks, is relatively robust to changes in convection, upwelling, or the applied ozone profile

Development of an invasively monitored porcine model of acetaminophen-induced acute liver failure

Background: The development of effective therapies for acute liver failure (ALF) is limited by our knowledge of the pathophysiology of this condition, and the lack of suitable large animal models of acetaminophen toxicity. Our aim was to develop a reproducible invasively-monitored porcine model of acetaminophen-induced ALF. Method: 35kg pigs were maintained under general anaesthesia and invasively monitored. Control pigs received a saline infusion, whereas ALF pigs received acetaminophen intravenously for 12 hours to maintain blood concentrations between 200-300 mg/l. Animals surviving 28 hours were euthanased. Results: Cytochrome p450 levels in phenobarbital pre-treated animals were significantly higher than non pre-treated animals (300 vs 100 pmol/mg protein). Control pigs (n=4) survived 28-hour anaesthesia without incident. Of nine pigs that received acetaminophen, four survived 20 hours and two survived 28 hours. Injured animals developed hypotension (mean arterial pressure; 40.8+/-5.9 vs 59+/-2.0 mmHg), increased cardiac output (7.26+/-1.86 vs 3.30+/-0.40 l/min) and decreased systemic vascular resistance (8.48+/-2.75 vs 16.2+/-1.76 mPa/s/m3). Dyspnoea developed as liver injury progressed and the increased pulmonary vascular resistance (636+/-95 vs 301+/-26.9 mPa/s/m3) observed may reflect the development of respiratory distress syndrome. Liver damage was confirmed by deterioration in pH (7.23+/-0.05 vs 7.45+/-0.02) and prothrombin time (36+/-2 vs 8.9+/-0.3 seconds) compared with controls. Factor V and VII levels were reduced to 9.3 and 15.5% of starting values in injured animals. A marked increase in serum AST (471.5+/-210 vs 42+/-8.14) coincided with a marked reduction in serum albumin (11.5+/-1.71 vs 25+/-1 g/dL) in injured animals. Animals displayed evidence of renal impairment; mean creatinine levels 280.2+/-36.5 vs 131.6+/-9.33 mumol/l. Liver histology revealed evidence of severe centrilobular necrosis with coagulative necrosis. Marked renal tubular necrosis was also seen. Methaemoglobin levels did not rise >5%. Intracranial hypertension was not seen (ICP monitoring), but there was biochemical evidence of encephalopathy by the reduction of Fischer's ratio from 5.6 +/- 1.1 to 0.45 +/- 0.06. Conclusion: We have developed a reproducible large animal model of acetaminophen-induced liver failure, which allows in-depth investigation of the pathophysiological basis of this condition. Furthermore, this represents an important large animal model for testing artificial liver support systems

Ecological and Behavioural Correlates of Intracellular Buffering Capacity in the Muscles of Antarctic Fishes

Five species of antarctic fishes can be arranged in order of increasing anaerobic capacity of the white muscles for burst swimming: Rhigophila dearborni (Zoarcidae), icefish (Channichthyidae), Dissostichus mawsoni, Trematomus centronotus, and Pagothenia borchgrevinki (Nototheniidae). This order reflects in-creasing dependence on anaerobic work done during short bursts of speed during prey capture or predator avoidance. Buffer capacity (beta) for white muscle was lower than that of behaviourally equivalent fish from lower latitudes and beta is itself temperature-dependent

Potentials of leaves of Aspilia africana (Compositae) in wound care: an experimental evaluation

<p>Abstract</p> <p>Background</p> <p>The potentials of the leaves of the haemorrhage plant, <it>Aspilia africana </it>C. D Adams (Compositae) in wound care was evaluated using experimental models. <it>A. africana</it>, which is widespread in Africa, is used in traditional medicine to stop bleeding from wounds, clean the surfaces of sores, in the treatment of rheumatic pains, bee and scorpion stings and for removal of opacities and foreign bodies from the eyes. The present study was undertaken to evaluate the potentials for use of leaves of this plant in wound care.</p> <p>Methods</p> <p>The effect of the methanol extract (ME) and the hexane (HF) and methanol (MF) fractions (obtained by cold maceration and graded solvent extraction respectively) on bleeding/clotting time of fresh experimentally-induced wounds in rats, coagulation time of whole rat blood, growth of microbial wound contaminants and rate of healing of experimentally-induced wounds in rats were studied as well as the acute toxicity and lethality (LD₅₀) of the methanol extract and phytochemical analysis of the extract and fractions.</p> <p>Results</p> <p>The extract and fractions significantly (<it>P </it>< 0.05) reduced bleeding/clotting time in rats and decreased coagulation time of whole rat blood in order of magnitude of effect: MF>ME>HF. Also, the extract and fractions caused varying degrees of inhibition of the growth of clinical isolates of <it>Pseudomonas fluorescens </it>and <it>Staphylococcus aureus</it>, as well as typed strains of <it>Ps. aeruginosa </it>(ATCC 10145) and <it>Staph. aureus </it>(ATCC 12600), and reduced epithelialisation period of wounds experimentally-induced in rats. Acute toxicity and lethality (LD₅₀) test in mice established an i.p LD₅₀of 894 mg/kg for the methanol extract (ME). Phytochemical analysis revealed the presence of alkaloids, saponins, tannins, flavonoids, resins, sterols, terpenoids and carbohydrates.</p> <p>Conclusion</p> <p>The leaves of <it>A. africana </it>possess constituents capable of arresting wound bleeding, inhibiting the growth of microbial wound contaminants and accelerating wound healing which suggest good potentials for use in wound care.</p

A prospective, cross-sectional study of anaemia and peripheral iron status in antiretroviral naïve, HIV-1 infected children in Cape Town, South Africa

BACKGROUND: Anaemia is a common manifestation of paediatric HIV infection. Although there are many causes, anaemia of chronic diseases is the most frequent type. In poor countries iron deficiency is widespread. It is probable that many HIV-infected children in these countries are also iron deficient. This study describes the relationship between paediatric HIV infection and anaemia, and documents the peripheral iron status of antiretroviral naive, HIV-infected children. METHODS: Sixty children were evaluated prospectively. Investigations included CD4+ count, haemoglobin concentration (Hb), red blood cell (RBC) morphology, and iron studies. RESULTS: Anaemia was present in 73% of children. Compared to mild HIV infection, median Hb was lower in children with moderate clinical infection (104 g/L v 112 g/L, p = 0.04) and severe clinical infection (96 g/L v 112 g/L, p = 0.006), and more children with severe infection were anaemic (92% v 58%, 0.04). There was a significant relationship between immunological status and Hb. 68% had abnormal RBC morphology. Significantly more children with moderate and severe disease, and severe immunosuppression had abnormal RBC morphology. 52% were iron-depleted, 20% had iron-deficient erythropoiesis and 18% iron deficiency anaemia (IDA). 16% (7/44) of anaemic children had microcytosis and hypochromia. Median soluble transferrin receptor concentration was significantly higher in those with microcytic hypochromic anaemia (42.0 nmol/L v 30.0 nmol/L, p = 0.008). CONCLUSIONS: Both the proportion of anaemic children and the median Hb were associated with disease status. Iron depletion and IDA are major problems in HIV-infected children in South Africa

Determination of βS haplotypes in patients with sickle-cell anemia in the state of Rio Grande do Norte, Brazil

βS haplotypes were studied in 47 non-related patients with sickle-cell anemia from the state of Rio Grande do Norte, Brazil. Molecular analysis was conducted by PCR/RFLP using restriction endonucleases XmnI, HindIII, HincII and HinfI to analyze six polymorphic sites from the beta cluster. Twenty-seven patients (57.5%) were identified with genotype CAR/CAR, 9 (19.1%) CAR/BEN, 6 (12.8%) CAR/CAM, 1 (2.1%) BEN/BEN, 2 (4.3%) CAR/Atp, 1 (2.1%) BEN/Atp and 1 (2.1%) with genotype Atp/Atp. The greater frequency of Cameroon haplotypes compared to other Brazilian states suggests the existence of a peculiarity of African origin in the state of Rio Grande do Norte