184 research outputs found
A Lagrangian constraint analysis of first order classical field theories with an application to gravity
We present a method that is optimized to explicitly obtain all the
constraints and thereby count the propagating degrees of freedom in (almost
all) manifestly first order classical field theories. Our proposal uses as its
only inputs a Lagrangian density and the identification of the a priori
independent field variables it depends on. This coordinate-dependent, purely
Lagrangian approach is complementary to and in perfect agreement with the
related vast literature. Besides, generally overlooked technical challenges and
problems derived from an incomplete analysis are addressed in detail. The
theoretical framework is minutely illustrated in the Maxwell, Proca and
Palatini theories for all finite spacetime dimensions. Our novel
analysis of Palatini gravity constitutes a noteworthy set of results on its
own. In particular, its computational simplicity is visible, as compared to
previous Hamiltonian studies. We argue for the potential value of both the
method and the given examples in the context of generalized Proca and their
coupling to gravity. The possibilities of the method are not exhausted by this
concrete proposal.Comment: 44 pages, 1 figure. v2: references added; journal versio
Singularity Avoidance of Charged Black Holes in Loop Quantum Gravity
Based on spherically symmetric reduction of loop quantum gravity,
quantization of the portion interior to the horizon of a Reissner-Nordstr\"{o}m
black hole is studied. Classical phase space variables of all regions of such a
black hole are calculated for the physical case . This calculation
suggests a candidate for a classically unbounded function of which all
divergent components of the curvature scalar are composed. The corresponding
quantum operator is constructed and is shown explicitly to possess a bounded
operator. Comparison of the obtained result with the one for the Swcharzschild
case shows that the upper bound of the curvature operator of a charged black
hole reduces to that of Schwarzschild at the limit . This
local avoidance of singularity together with non-singular evolution equation
indicates the role quantum geometry can play in treating classical singularity
of such black holes.Comment: To be appeared in International Journal of Theoretical Physic
Squamous cell carcinoma (SCC) arising in esophageal colon interposition
The idea of using the colon to replace a resected esophagus has a long history. The colon has become a favored organ for esophageal reconstruction in adults with esophageal cancer when the stomach is not suitable or is unavailable. In this article, we introduce an 84-year-old woman that she had surgery 40 years ago and presented with an invasive well differentiated squamous cell carcinoma of colonic origin in reconstructed esophagus. © 2017 The Author
Green's functions and Hadamard parametrices for vector and tensor fields in general linear covariant gauges
We determine the retarded and advanced Green’s functions and Hadamard parametrices in curved spacetimes for linearized massive and massless gauge bosons and linearized Einstein gravity with a cosmological constant in general linear covariant gauges. These vector and tensor parametrices contain additional singular terms compared with their Feynman/de Donder-gauge counterpart. We also give explicit recursion relations for the Hadamard coefficients, and indicate their generalization to n dimensions. Furthermore, we express the divergence and trace of the vector and tensor Green’s functions in terms of derivatives of scalar and vector Green’s functions, and show how these relations appear as Ward identities in the free quantum theory
Antitumor effect of IP-10 by using two different approaches: Live delivery system and gene therapy
Purpose: Immunotherapy is one of the treatment strategies for breast cancer, the most common cancer in women worldwide. In this approach, the patient�s immune system is stimulated to attack microscopic tumors and control metastasis. Here, we used interferon γ-induced protein 10 (IP-10), which induces and strengthens antitumor immunity, as an immunotherapeutic agent. We employed Leishmania tarentolae, a nonpathogenic lizard parasite that lacks the ability to persist in mammalian macrophages, was used as a live delivery system for carrying the immunotherapeutic agent. It has been already shown that arginase activity, and consequently, polyamine production, are associated with tumor progression. Methods: A live delivery system was constructed by stable transfection of pLEXSY plasmid containing the IP-10-enhanced green fluorescent protein (IP-10- egfp) fusion gene into L. tarentolae. Then, the presence of the IP-10-egfp gene and the accurate integration location into the parasite genome were confirmed. The therapeutic efficacy of IP- 10 delivered via L. tarentolae and recombinant pcDNA-(IP- 10-egfp) plasmid was compared by determining the arginase activity in a mouse 4T1 breast cancer model. Results: The pcDNA- (IP-10-egfp) group showed a significant reduction in tumor weight and growth. Histological evaluation also revealed that only this group demonstrated inhibition of metastasis to the lung tissue. The arginase activity in the tissue of the pcDNA-(IP- 10-egfp) mice significantly decreased in comparison with that in normal mice. No significant difference was observed in arginase activity in the sera of mice receiving other therapeutic strategies. Conclusion: Our data indicates that IP-10 immunotherapy is a promising strategy for breast cancer treatment, as shown in the 4T1-implanted BALB/c mouse model. However, the L. tarentolae- (IP-10-EGFP) live delivery system requires dose modifications to achieve efficacy in the applied regimen (six injections in 3 weeks). Our results indicate that the arginase assay could be a good biomarker to differentiate tumoral tissues from the normal ones. © 2016 Korean Breast Cancer Society. All rights reserved
Role of polymorphisms of the endothelial nitric oxide synthase gene in predicting slow-flow phenomenon after primary percutaneous coronary intervention
Objective: The aim of the present study was to examine the association between 2 polymorphisms of the endothelial nitric oxide (eNOS) gene (-786T>C and +894G>T) and the no-reflow/slow-flow phenomenon in post-primary percutaneous coronary intervention (PPCI) patients. Methods: A total of 103 post-PPCI patients were enrolled. Coronary no-reflow phenomenon was defined as a Thrombolysis in Myocardial Infarction (TIMI) flow grade 0-1 and coronary slow-flow phenomenon (CSFP) was defined as a TIMI flow grade �2. Results: Due to the small number of post-PPCI patients with the no-reflow phenomenon (n=4), the primary comparison was made between CSFP (n=20) and normal flow (n=83) groups. There was a greater frequency of CSFP among carriers of the-786C allele of the eNOS-786T>C polymorphism (odds ratio OR: 3.90; 95% confidence interval CI: 0.87-17.45; p=0.07). However, no such association was detected between the +894T allele of the eNOS +894G>T and CSFP (OR: 0.92; 95% CI: 0.21-3.98; p=0.91). In the adjusted analysis, the-786T>C polymorphism did not reach statistical significance. Conclusion: There was no significant association between CSFP and 2 of the most common polymorphisms of the eNOS gene in post-PPCI patients. © 2020 Turkish Society of Cardiology
C-Terminal Domain Deletion Enhances the Protective Activity of cpa/cpb Loaded Solid Lipid Nanoparticles against Leishmania major in BALB/c Mice
Cutaneous leishmaniasis (CL) is the most common form of leishmaniasis with an annual incidence of approximately 2 million cases and is endemic in 88 countries, including Iran. CL's continued spread, along with rather ineffectual treatments and drug-resistant variants emergence has increased the need for advanced preventive strategies. We studied Type II cysteine proteinase (CPA) and Type I (CPB) with its C-terminal extension (CTE) as cocktail DNA vaccine against murine and canine leishmaniasis. However, adjuvants' success in enhancing immune responses to selected antigens led us to refocus our vaccine development programs. Herein, we discuss cationic solid lipid nanoparticles' (cSLN) ability to improve vaccine-induced protective efficacy against CL and subsequent lesion size and parasite load reduction in BALB/c mice. For this work, we evaluated five different conventional as well as novel parasite detection techniques, i.e., footpad imaging, footpad flowcytometry and lymph node flowcytometry for disease progression assessments. Vaccination with cSLN-cpa/cpb-CTE formulation showed highest parasite inhibition at 3-month post vaccination. Immunized mice showed reduced IL-5 level and significant IFN-ã increase, compared to control groups. We think our study represents a potential future and a major step forward in vaccine development against leishmaniasis
DNA plasmid coding for Phlebotomus sergenti salivary protein PsSP9, a member of the SP15 family of proteins, protects against Leishmania tropica
Background: The vector-borne disease leishmaniasis is transmitted to humans by infected female sand flies, which transmits Leishmania parasites together with saliva during blood feeding. In Iran, cutaneous leishmaniasis (CL) is caused by Leishmania (L.) major and L. tropica, and their main vectors are Phlebotomus (Ph.) papatasi and Ph. sergenti, respectively. Previous studies have demonstrated that mice immunized with the salivary gland homogenate (SGH) of Ph. papatasi or subjected to bites from uninfected sand flies are protected against L. major infection. Methods and results: In this work we tested the immune response in BALB/c mice to 14 different plasmids coding for the most abundant salivary proteins of Ph. sergenti. The plasmid coding for the salivary protein PsSP9 induced a DTH response in the presence of a significant increase of IFN-γ expression in draining lymph nodes (dLN) as compared to control plasmid and no detectable PsSP9 antibody response. Animals immunized with whole Ph. sergenti SGH developed only a saliva-specific antibody response and no DTH response. Mice immunized with whole Ph. sergenti saliva and challenged intradermally with L. tropica plus Ph. sergenti SGH in their ears, exhibited no protective effect. In contrast, PsSP9-immunized mice showed protection against L. tropica infection resulting in a reduction in nodule size, disease burden and parasite burden compared to controls. Two months post infection, protection was associated with a significant increase in the ratio of IFN-γ to IL-5 expression in the dLN compared to controls. Conclusion: This study demonstrates that while immunity to the whole Ph. sergenti saliva does not induce a protective response against cutaneous leishmaniasis in BALB/c mice, PsSP9, a member of the PpSP15 family of Ph. sergenti salivary proteins, provides protection against L. tropica infection. These results suggest that this family of proteins in Ph. sergenti, Ph. duboscqi and Ph. papatasi may have similar immunogenic and protective properties against different Leishmania species. Indeed, this anti-saliva immunity may act as an adjuvant to accelerate the cell-mediated immune response to co-administered Leishmania antigens, or even cause the activation of infected macrophages to remove parasites more efficiently. These findings highlight the idea of applying arthropod saliva components in vaccination approaches for diseases caused by vector-borne pathogens. © 2019, Public Library of Science. All rights reserved
Nutrition and lung cancer: a case control study in Iran
Background: Despite many prospective and retrospective studies about the association of dietary habit and lung
cancer, the topic still remains controversial. So, this study aims to investigate the association of lung cancer with
dietary factors.
Method: In this study 242 lung cancer patients and their 484 matched controls on age, sex, and place of residence
were enrolled between October 2002 to 2005. Trained physicians interviewed all participants with standardized
questionnaires. The middle and upper third consumer groups were compared to the lower third according to the
distribution in controls unless the linear trend was significant across exposure groups.
Result: Conditional logistic regression was used to evaluate the association with lung cancer. In a multivariate
analysis fruit (Ptrend < 0.0001), vegetable (P = 0.001) and sunflower oil (P = 0.006) remained as protective factors and
rice (P = 0.008), bread (Ptrend = 0.04), liver (P = 0.004), butter (Ptrend = 0.04), white cheese (Ptrend < 0.0001), beef
(Ptrend = 0.005), vegetable ghee (P < 0.0001) and, animal ghee (P = 0.015) remained as risk factors of lung cancer.
Generally, we found positive trend between consumption of beef (P = 0.002), bread (P < 0.0001), and dairy
products (P < 0.0001) with lung cancer. In contrast, only fruits were inversely related to lung cancer (P < 0.0001).
Conclusion: It seems that vegetables, fruits, and sunflower oil could be protective factors and bread, rice, beef,
liver, dairy products, vegetable ghee, and animal ghee found to be possible risk factors for the development of
lung cancer in Iran
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