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Isomerism is ubiquitous in chemistry, physics, and biology. In atomic and molecular physics, in particular, isomer effects are well known in electron-impact phenomena; however, very little is known for positron collisions. Here we report on a set of experimental and theoretical cross sections for low-energy positron scattering from the three structural isomers of pentane: normal-pentane, isopentane, and neopentane. Total cross sections for positron scattering from normal-pentane and isopentane were measured at the University of Trento at incident energies between 0.1 and 50 eV. Calculations of the total cross sections, integral cross sections for elastic scattering, positronium formation, and electronic excitations plus direct ionization, as well as elastic differential cross sections were computed for all three isomers between 1 and 1000 eV using the independent atom model with screening corrected additivity rule. No definitive evidence of a significant isomer effect in positron scattering from the pentane isomers appears to be present.
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In this paper we report original measurements of total cross sections (TCSs) for positron scattering from the cyclic ethers oxirane (C(2)H(4)O), 1,4-dioxane (C(4)H(8)O(2)), and tetrahydropyran (C(5)H(10)O). The present experiments focus on the low energy range from â¼0.2 to 50 eV, with an energy resolution smaller than 300 meV. This study concludes our systematic investigation into TCSs for a class of organic compounds that can be thought of as sub-units or moieties to the nucleotides in living matter, and which as a consequence have become topical for scientists seeking to simulate particle tracks in matter. Note that as TCSs specify the mean free path between collisions in such simulations, they have enjoyed something of a recent renaissance in interest because of that application. For oxirane, we also report original Schwinger multichannel elastic integral cross section (ICS) calculations at the static and static plus polarisation levels, and with and without Born-closure that attempts to account for the permanent dipole moment of C(2)H(4)O. Those elastic ICSs are computed for the energy range 0.5-10 eV. To the best of our knowledge, there are no other experimental results or theoretical calculations against which we can compare the present positron TCSs. However, electron TCSs for oxirane (also known as ethylene oxide) and tetrahydropyran do currently exist in the literature and a comparison to them for each species will be presented.
Assuntos
Dioxanos/química , Óxido de Etileno/química , Piranos/química , Elétrons , Modelos Teóricos , Estrutura Molecular , Método de Monte Carlo , Espalhamento de RadiaçãoRESUMO
INTRODUCTION: Upfront criteria to foresee immune checkpoint inhibitors (ICIs) efficacy are far from being identified. Thus, we integrated blood descriptors of pro-inflammatory/immunosuppressive or effective anti-tumor response to non-invasively define predictive immune profiles in ICI-treated advanced non-small cell lung cancer (NSCLC). METHODS: Peripheral blood (PB) was prospectively collected at baseline from 109 consecutive NSCLC patients undergoing ICIs as first or more line treatment. Soluble PD-L1 (sPD-L1) (immunoassay), CD8+PD-1+ and NK (FACS) cells were assessed and interlaced to generate an Immune effector Score (IeffS). Lung Immune Prognostic Index (LIPI) was computed by LDH levels and derived Neutrophil-to-Lymphocyte Ratio (dNLR). All these parameters were correlated with survival outcome and treatment response. RESULTS: High sPD-L1 and low CD8+PD-1+ and NK number had negative impact on PFS (P < 0.001), OS (P < 0.01) and ICI-response (P < 0.05). Thus, sPD-L1high, CD8+PD-1+low and NKlow were considered as risk factors encompassing IeffS, whose prognostic power outperformed that of individual features and slightly exceeded that of LIPI. Accordingly, the absence of these risk factors portrayed a favorable IeffS characterizing patients with significantly (P < 0.001) prolonged PFS (median NR vs 2.3 months) and OS (median NR vs 4.1) and greater benefit from ICIs (P < 0.01). We then combined each risk parameter composing IeffS and LIPI (LDHhigh, dNLRhigh), thus defining three distinct prognostic classes. A remarkable impact of IeffS-LIPI integration was documented on survival outcome (PFS, HR = 4.61; 95%CI = 2.32-9.18; P < 0.001; OS, HR=4.03; 95%CI=1.91-8.67; P < 0.001) and ICI-response (AUC=0.90, 95%CI=0.81-0.97, P < 0.001). CONCLUSION: Composite risk models based on blood parameters featuring the tumor-host interaction might provide accurate prognostic scores able to predict ICI benefit in NSCLC patients.
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Carcinoma Pulmonar de Células não Pequenas , Neoplasias Pulmonares , Antígeno B7-H1 , Linfócitos T CD8-Positivos , Carcinoma Pulmonar de Células não Pequenas/terapia , Humanos , Imunoterapia , Células Matadoras Naturais , Neoplasias Pulmonares/terapia , Prognóstico , Receptor de Morte Celular Programada 1RESUMO
We report on total cross section measurements for positron scattering from dihydropyran (C(5)H(8)O), with the energy range of the present study being 0.15-48 eV. To the best of our knowledge, there are currently no other corresponding experimental data or theoretical computations against which we can compare our results. The effect of this species' important dipole moment and significant dipole polarizability on the scattering dynamics is considered, as is the opening of the positronium formation channel.
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The Ref-1 (also called APE or HAP1) protein is a bifunctional enzyme impacting on a wide variety of important cellular functions. It acts as a major member of the DNA base excision repair pathway. Moreover, Ref-1 stimulates the DNA-binding activity of several transcription factors (TFs) through the reduction of highly reactive cysteine residues. Therefore, it represents a mechanism that regulates eukaryotic gene expression in a fast way. However, it has been demonstrated that external stimuli directly act on Ref-1 by increasing its expression levels, a time-consuming mechanism representing a paradox in terms of rapidity of TF regulation. In this paper we demonstrate that this is only an apparent paradox. Exposure of B lymphocytes to H(2)O(2)induced a rapid and sustained increase in Ref-1 protein levels in the nucleus as evaluated by both western blot analysis and by pulse-chase experiments. A time course, two color in situ immunocytochemistry indicated that the up-regulation of Ref-1 in the nucleus at <30 min was primarily the consequence of translocation of its cytoplasmic form. This early nuclear accumulation is effective in modulating the DNA-binding activity of the B cell-specific activator protein BSAP/Pax-5. In fact, EMSA experiments demonstrate that a transient interaction with Ref-1 up-regulates the DNA-binding activity of BSAP/Pax-5. Moreover, in a co-transfection experiment, Ref-1 increased the BSAP/Pax-5 activating effect on an oligomerized BSAP/Pax-5 binding site of the CD19 promoter by 5- to 8-fold. Thus, Ref-1 mediates its effect by up-regulating the DNA-binding activity of BSAP/Pax-5, accounting for a new and fast outside/inside pathway of signaling in B cells.
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Linfócitos B/fisiologia , Carbono-Oxigênio Liases/fisiologia , DNA Liase (Sítios Apurínicos ou Apirimidínicos) , Proteínas de Ligação a DNA/fisiologia , Proteínas Nucleares/fisiologia , Transdução de Sinais/fisiologia , Transporte Biológico/fisiologia , Linhagem Celular , Humanos , Oxirredução , Fator de Transcrição PAX5 , Fatores de Transcrição/fisiologiaRESUMO
Control of apolipoprotein B (apo B) secretion in hepatocytes occurs partly at the post-translational level. The key step in this process appears to be intracellular degradation of newly synthesized apo B. The aim of this paper was to investigate the mechanisms that regulate apo B secretion by Hep G2 cells, in response to the inhibition of Acyl-CoA Acyltransferase (ACAT) by the compound Sandoz 58035 (S-58035). S-58035 (20 microM) reduced cholesteryl ester synthesis from [14C]oleate by 95%, and increased significantly, in a dose-dependent manner, (2-100 microM) apo B secretion, either in control conditions (from 78 +/- 4.3 to 126 +/- 6.1 ng apo B-100/mg cell protein/4 h) or upon stimulation of apo B secretion by oleate (from 134 +/- 4.23 to 177 +/- 4.3 ng apo B/mg cell protein/4 h). This increased secretion of newly synthesized apo B-100 was confirmed by pulse experiments and by gradient ultracentrifugation of the media. Moreover pulse-chase experiments showed that the addition of S-58035 reduced intracellular degradation of apo B-100, both in control conditions and in the presence of oleate. S-58035 (20 microM) did not affect total cellular cholesterol content, but free cholesterol increased with a concomitant decrease of cholesteryl ester (-20%). S-58035 increased cellular triglyceride mass, which was observed in basal conditions (from 12.8 +/- 1.09 to 22.7 +/- 2.7 micrograms TG/mg cellular protein) and also in presence of oleate (from 48 +/- 0.53 to 59 +/- 6.3 micrograms TG/mg cellular protein). This effect is due to a stimulation of triglyceride synthesis, as determined by incorporation of [3H]glycerol into cellular triglycerides. From these data we conclude that, under our experimental conditions, triglyceride synthesis and/or availability is likely to control intracellular degradation of apo B.
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Apolipoproteínas B/metabolismo , Ésteres do Colesterol/antagonistas & inibidores , Ésteres do Colesterol/biossíntese , Fígado/metabolismo , Compostos de Organossilício , Amidas/farmacologia , Apolipoproteína B-100 , Relação Dose-Resposta a Droga , Inibidores Enzimáticos/farmacologia , Ensaio de Imunoadsorção Enzimática , Humanos , Metabolismo dos Lipídeos , Ácido Oleico/farmacologia , Esterol O-Aciltransferase/antagonistas & inibidores , Triglicerídeos/biossíntese , Células Tumorais CultivadasRESUMO
Intracellular cholesterol biosynthesis may play a key role in supplying cholesterol (as cholesteryl ester) for the neutral core of very low density lipoprotein (VLDL), thus modulating the secretion of apolipoprotein B-100 (apo B-100) from hepatocytes. The effect of compound NK-104 was studied, a new competitive inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG CoA-reductase), on apo B-100 synthesis and secretion from the human hepatoma cell line Hep G2. Cells were preincubated with NK-104 (0.01-5 microM) in the presence or absence of oleate (0.8 mM). Apo B-100 in the medium was determined by an enzyme-linked immunosorbent assay (ELISA). Incubation of Hep G2 with NK-104 resulted in a marked inhibition of cholesterogenesis (up to 95%), determined as incorporation of [14C]acetate into sterols, and decreased in a dose-dependent manner apo B-100 secretion, both in basal conditions (from 110 to 82 ng/mg cell protein, P < 0.01) and after incubation with oleate (from 227 to 165 ng/mg cell protein, P < 0.01). Density gradient for distribution of apo B-100 secreted, showed that this decrease was essentially due to a reduction of apo B-100 associated with lipoproteins in the density range of low density lipoproteins (LDL). Pulse chase experiment demonstrated that NK-104 did not affect the synthetic rate of apo B-100 but increased intracellular degradation of newly synthesized protein. The compound had only marginal effect on the mass of intracellular triglyceride but significantly decreased intracellular mass of free cholesterol and cholesteryl ester (P < 0.01). It is speculated that the ability of compound NK-104 to decrease apo B-100 secretion from Hep G2 cells is due to a decreased intracellular cholesterol availability.
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Apolipoproteínas B/metabolismo , Inibidores Enzimáticos/farmacologia , Inibidores de Hidroximetilglutaril-CoA Redutases/farmacologia , Fígado/metabolismo , Quinolinas/farmacologia , Apolipoproteína B-100 , Apolipoproteínas B/efeitos dos fármacos , Colesterol/metabolismo , Relação Dose-Resposta a Droga , Ensaio de Imunoadsorção Enzimática , Humanos , Técnicas In Vitro , Metabolismo dos Lipídeos , Células Tumorais Cultivadas/metabolismoRESUMO
Intralipid (20 percent, 500 ml) was infused fast (5 h) or slow (10 h) randomly in patients with lung injury to relate changes in plasma prostaglandin (PG) concentrations to gas exchange and pulmonary hemodynamics. Data were collected at baseline, midpoint of infusion, and 2 h following infusion. Vasodilator and vasoconstrictor PG metabolites, 6-keto-PGF1 alpha, and thromboxane B2, respectively, were measured in radial arterial blood samples. Slow Intralipid infusion increased shunt fraction (QS/QT) without changing mean pulmonary artery pressure (MPAP), whereas fast Intralipid infusion increased MPAP without changing QS/QT. Prostaglandin levels did not change significantly during either infusion. However, in both groups when the PG substrate was removed, hemodynamic and metabolite values decreased in parallel. In conclusion, we were unable to demonstrate a cause and effect relationship between plasma levels of 6-keto-PGF1 alpha and thromboxane B2 and the observed pulmonary hemodynamic response to slow or fast Intralipid infusion.
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6-Cetoprostaglandina F1 alfa/sangue , Emulsões Gordurosas Intravenosas/administração & dosagem , Circulação Pulmonar , Troca Gasosa Pulmonar , Tromboxano B2/sangue , Pressão Sanguínea , Humanos , Artéria Pulmonar/fisiopatologia , Pressão Propulsora Pulmonar , Síndrome do Desconforto Respiratório/sangue , Síndrome do Desconforto Respiratório/fisiopatologia , Síndrome do Desconforto Respiratório/terapiaRESUMO
Hemodynamic consequences of pressure support ventilation (PSV) were compared with intermittent mandatory ventilation (IMV) in 20 patients following aortocoronary bypass. On the morning following surgery, all patients were weaned by IMV to a rate of eight breaths per minute, tidal volume of 12 ml/kg and inspired oxygen concentration of 40 per cent. With patients awake and able to breath spontaneously, PSV was begun at 20 cm of water. In patients with static lung compliance, less than 0.06 l/cm H2O, 30 cm H2O of PSV was used. Subsequently, all patients were weaned to PSV 10 cm of water, continuous positive airway pressure (CPAP) at 5 cm water and extubated. Hemodynamic data including oxygen transport were obtained at each level of PSV and at IMV prior to weaning. Analysis using ANOVA showed comparable hemodynamic and oxygen transport parameters for PSV of 30 cm H2O in comparison with IMV. PSV at levels of 20 and 10 cm H2O produced statistically significant increases in heart rate, mean arterial pressure, central venous pressure, and pulmonary capillary wedge pressure. Cardiac output was stable, and these increases were not clinically significant. In awake patients following cardiac surgery, PSV up to 30 cm H2O can be safely applied without hemodynamic embarrassment in patients with good left ventricular ejection fractions.
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Ponte de Artéria Coronária , Hemodinâmica , Respiração com Pressão Positiva/normas , Cuidados Pós-Operatórios , Respiração Artificial/normas , Gasometria , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Monitorização Fisiológica , Respiração com Pressão Positiva/métodos , Respiração Artificial/métodos , Desmame do RespiradorRESUMO
The case of a sixteen year old girl with hereditary spherocytosis, submitted to splenectomy, is presented. After operation the patient had four serious infections; for this reason she is now treated by antibiotic prophylaxis.
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Infecções Bacterianas/prevenção & controle , Esferocitose Hereditária/cirurgia , Esplenectomia/efeitos adversos , Adolescente , Infecções Bacterianas/etiologia , Suscetibilidade a Doenças , Feminino , HumanosRESUMO
The diagnostic iter of a case of Streptococcus mitis endocarditis is reported. Bacterial endocarditis was diagnosed in a 32-year-old patient following ultrasound cardiography and microbiological tests. The paper stresses the importance of ultrasound cardiography in the diagnosis of bacterial endocarditis.
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Endocardite Bacteriana/diagnóstico por imagem , Infecções Estreptocócicas , Adulto , Endocardite Bacteriana/microbiologia , Feminino , Humanos , UltrassonografiaRESUMO
The importance of adequate oxygenation in critically ill patients is widely recognized. Pulse oximetry (PO) is a non-invasive, rapid technique of arterial hemoglobin oxygen saturation (SaO2) measurement. This report is a review of our experience using the PO during air medical transport. A chart review was conducted on patients who used air medical transport between October 1988 and March 1989. Types of patients included trauma and ICU patients who were transported from either accident scenes or outlying hospitals. SaO2 and vital sign (VS) measurements were obtained pre and postflight, and inflight interventions were documented. Four groups of patients were identified: Group 1: PO used, inflight intervention employed; Group II: PO used, no inflight intervention employed; Group III: no PO used, inflight intervention employed; Group IV: no PO used, no inflight intervention employed. A dependent, paired-t-test was used to compare pre and postflight SaO2 and VS measurements. The mean difference between pre and postflight measurements of SaO2, systolic blood pressure, and pulse rate were calculated within each group. Then, an ANOVA with post-hoc Newman-Keuls Test compared the means between the four groups. Of the 137 patients reviewed, 82 used PO and 55 patients did not due to technical or anatomic problems. Of the 82 patients who used PO, 19 received an inflight intervention.(ABSTRACT TRUNCATED AT 250 WORDS)
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Aeronaves , Ambulâncias , Avaliação de Resultados em Cuidados de Saúde/estatística & dados numéricos , Oximetria/estatística & dados numéricos , Medicina de Emergência/normas , Humanos , IllinoisRESUMO
OBJECTIVE: To examine the cardiovascular adjustments and pattern of gas exchange that occur during hemodilution. DESIGN: Nonrandomized prospective study. SETTING: Operating room in a university hospital. PATIENTS: Seven patients undergoing elective aortocoronary artery bypass surgery. INTERVENTIONS: Before initiating cardiopulmonary bypass, the patients' hematocrit levels were decreased to approximately 15%. This hemodilution was done by removing a sufficient amount of autologous blood from the aortic cannula and replacing it with a sufficient amount of crystalloid solution. After the discontinuation of cardiopulmonary bypass, measurements were made at a hematocrit of approximately 15%. Then, after autologous blood infusion, measurements were made at a hematocrit of 20%, followed by more blood infusion to approximately 25% with repeat measurements. MEASUREMENTS AND MAIN RESULTS: The following measurements were made before hemodilution and then at all three levels of hemodilution: heart rate, mean arterial pressure (MAP), right atrial pressure, mean pulmonary artery pressure, pulmonary artery occlusion pressure, and cardiac output. From these measurements, the following derived variables were calculated: cardiac index, systemic vascular resistance, and pulmonary vascular resistance. From measurements of arterial oxygen content, mixed venous oxygen content, and cardiac output, intrapulmonary shunt (Qsp/Qt), oxygen uptake (VO2), oxygen extraction ratio, and oxygen delivery (DO2) were derived. The MAP was lowest (57 +/- 3 [SD] vs. 92 +/- 3 mm Hg) at the lowest hematocrit. The cardiac index was highest (4.0 +/- 0.3 vs. 2.3 +/- 0.6 L/min.m2) at the lowest hematocrit. DO2 was lowest at the lowest hematocrit but VO2 remained constant at all levels of hematocrit. The oxygen extraction ratio increased as hematocrit decreased. With progressive increases in hematocrit, DO2 increased and Qsp/Qt decreased. CONCLUSIONS: The data suggest that, during hemodilution, tissue autoregulation of VO2 and utilization are not impaired, but gas exchange function (Qsp/Qt) is impaired.
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Hemodiluição , Hemodinâmica , Troca Gasosa Pulmonar , Pressão Sanguínea , Transfusão de Sangue Autóloga , Ponte Cardiopulmonar , Humanos , Oxigênio/sangue , Estudos Prospectivos , Circulação PulmonarRESUMO
The two Ca2+ pumps of higher eucaryotes are strictly targeted to different membrane systems: the plasma membrane (PMCA) and the sarco(endo)plasmic reticulum (SERCA). Chimeric constructs of the two pumps expressed in COS-7 cells have revealed a strong signal for endoplasmic reticulum retention in the N-terminal cytosolic portion of the SERCA pump: the signal is contained in a stretch of 28 amino acids that follows the N-terminus. A second, but masked, endoplasmic reticulum retention signal is contained in a cytosolic C-terminal sequence immediately preceding the calmodulin-binding domain of the Ca2+ pump. Selective mutations on the SERCA pump have led to the conclusion that 5 conserved residue membrane domains (TM)4, 5, and 6 form the Ca2+ channel through the pump protein. A comparative sequence inspection has failed to reveal any of these residues in TM5 of the PMCA pump. Mutation of the conserved residue in TM4 and of two in TM6 abolished the ability of the pump to form the Ca(2+)-dependent phosphoenzyme. However, one of the mutations (N979, TM6) also caused retention of the PMCA pump in the reticulum, suggesting structural alterations. Of the four basic isoforms of the pump, two (1, 4) are ubiquitously expressed, two (2, 3) are essentially brain specific. Isoform 2 has the highest calmodulin affinity. Primary cultures of cerebellar granule cells from newborn rats did not express isoforms 2 and 3 at plating time. Incubation of the cells in depolarizing concentrations of KCl, which promote Ca2+ influx, promoted the expression of isoforms 2 and 3, and of a brain specific spliced variant of isoform 1. Incubation of the cells in L-type Ca2+ channel blockers abolished the upregulation of the pump genes.