How to climb the face of a mountain

EnThe shortest line connecting a point at the base of a mountain with the top is a geodesic on the surface of the mountain. But this path is often unpracticable since the inclination of the geodesic with respect the horizontal is often too high to being directly overcome by a climber. We here propose a strategy for reaching the top along curves not exceeding the maximum inclination superable by the climber.We here discuss two particular examples for which an explicit solution is obtainable in terms of elliptic functions

Effects of estrogen peripheral metabolism in rheumatoid arthritis

It is well known that the immune reactivity is modulated by gender. In fact, women show a more effective immune response as well as a more frequent development of autoimmune diseases. In particular, 17b-estradiol (E2) in patients with systemic inflammatory diseases leads to an higher production of IgG and IgM in peripheral blood mononucleated cells (PBMC) and the secretion of metalloproteinases and IL-6 by synovial fibroblasts. The effect of E2 seems to be partially related to its concentration. In fact, at the physiological concentration, E2 seems to exert a pro-inflammatory effect, while at pharmacological concentrations shows anti-inflammatory effects. Steroid hormones can be converted in downstream hormones along defined pathways. The conversion of dehydroepiandrosterone (DHEA) in peripheral macrophages leads to the androgen production. Subsequently the enzyme aromatase converts androgens in estrogens, and its activity is increased by some inflammatory cytokines such as IL-1b, IL-6 and TNF-a. In the synovial fluids of rheumatoid arthritis (RA) patients the levels of estrogens result significantly increased compared with controls, showing the consequence of this unbalanced steroid metabolism. Furthermore, the metabolism of estrogens leads to some downstream hydroxylated metabolites, that are not waste products, but still active molecules in the inflammatory response. In fact, it has been found that synovial fluids of RA patients present a different ratio of 16-hydroxylated estrogen metabolites/ 2-hydroxylated metabolites, confirming that also the unbalanced metabolism of estrogens and not only the estrogen concentration seems to be related to the development and worsening of rheumatoid arthritis

A drifting impact oscillator with periodic impulsive loading: Application to percussive drilling

Peer reviewe

Sex hormone modulation of cell growth and apoptosis of the human monocytic/macrophage cell line

Sex hormones seem to modulate the immune/inflammatory responses by different mechanisms in female and male rheumatoid arthritis patients. The effects of 17β-oestradiol and of testosterone were tested on the cultured human monocytic/macrophage cell line (THP-1) activated with IFN-γ in order to investigate their role in cell proliferation and apoptosis. Activated human THP-1 cells were cultured in the presence of 17β-oestradiol and testosterone (final concentration, 10 nM). The evaluation of markers of cell proliferation included the NF-κB DNA-binding assay, the NF-κB inhibition complex, the proliferating cell nuclear antigen expression and the methyl-tetrazolium salt test. Apoptosis was detected by the annexin V-propidium assay and by the cleaved poly-ADP ribose polymerase expression. Specific methods included flow analysis cytometry scatter analysis, immunocytochemistry and western blot analysis. Cell growth inhibition and increased apoptosis were observed in testosterone-treated THP-1 cells. Increased poly-ADP ribose polymerase-cleaved expression and decreased proliferating cell nuclear antigen expression, as well as an increase of IκB-α and a decrease of the IκB-α phosphorylated form (ser 32), were found in testosterone-treated THP-1 cells. However, the NF-κB DNA binding was found increased in 17β-oestradiol-treated THP-1 cells. The treatment with staurosporine (enhancer of apoptosis) induced decreased NF-κB DNA binding in all conditions, but particularly in testosterone-treated THP-1 cells. Treatment of THP-1 by sex hormones was found to influence cell proliferation and apoptosis. Androgens were found to increase the apoptosis, and oestrogens showed a protective trend on cell death – both acting as modulators of the NF-κB complex

[17beta-Estradiol and testosterone influence the mRNA expression and the time course of inflammatory cytokines in activated human monocytic cell line (THP-1)].

Objective: The aim of this study was to evaluate the effects of 17b-estradiol (E2) and testosterone (T) on the mRNA expression of IL-1b, IL-6, TNF-a and TGF-b in cultured human monocytic cells (THP-1) after INF-g activation. Methods: THP-1 were cultured with E2 and T (10 nM) for 24 hs and then activated with INF-g (500 U/ml), during different periods of time (1, 3, 6, and 12 hs). After total RNA extraction, all samples were analyzed by multiple RT-PCR to detect mRNA expression of the selected cytokines. Results: Cells cultured without hormonal treatment expressed IL-1b mRNA after 1 h; on the contrary TNF-a, TGF-b and IL-6 mRNA were expressed only after 3 hs. At 6 and 12 hs only IL-6 mRNA was still expressed. Interestingly, cells cultured with testosterone never expressed IL-1b nor TNF-a mRNA and showed an IL-6 mRNA expression similar to the untreated controls at 3, 6 and 12 hours. On the contrary, cells treated with E2 showed the expression of all cytokines at 3 and 12 hs, and in general showed an higher expression of all the analyzed cytokines mRNA when compared to the other conditions. Conclusions: This study suggests that sex hormones may modulate the cytokine mRNA expression in the inflammatory cells. In fact, T inhibits TNF-a production at all the tested times, whereas E2 seems to accelerate and to enhance the inflammatory response. Therefore, the altered sex hormone ratio, as observed in the synovial fluid of RA patients (high E2/low T), might contribute to the occurrence and last of synovitis

A comprehensive survey of the analytical, numerical and experimental methodologies for dynamics of multibody mechanical systems with clearance or imperfect joints

"Available online 19 December 2017"A comprehensive survey of the literature of the most relevant analytical, numerical, and experimental approaches for the kinematic and dynamic analyses of multibody mechanical systems with clearance joints is presented in this review. Both dry and lubricated clearance joints are addressed here, and an effort is made to include a large number of research works in this particular field, which have been published since the 1960′s. First, the most frequently utilized methods for modeling planar and spatial multibody mechanical systems with clearance joints are analyzed, and compared. Other important phenomena commonly associated with clearance joint models, such as wear, non-smooth behavior, optimization and control, chaos, and uncertainty and links’ flexibility, are then discussed. The main assumptions procedures and conclusions for the different methodologies are also examined and compared. Finally, future developments and new applications of clearance joint modeling and analysis are highlighted.This research was supported in part by the China 111 Project (B16003) and the National Natural Science Foundation of China under Grants 11290151, 11472042 and 11221202. The work was also supported by the Portuguese Foundation for Science and Technology with the reference project UID/EEA/04436/2013, by FEDER funds through the COMPETE 2020 – Programa Operacional Competitividade e Internacionalização (POCI) with the reference project POCI-01-0145-FEDER-006941.info:eu-repo/semantics/publishedVersio

CTLA4-Ig interacts with cultured synovial macrophages from rheumatoid arthritis patients and downregulates cytokine production

Introduction: Co-stimulatory signal B7(CD80/CD86):CD28 is needed in order to activate T cells in immune response. Cytotoxic T lymphocyte-associated antigen-4-immunoglobulin (CTLA4-Ig) binding to the B7 molecules on antigen-presenting cells downregulates this activation and represents a recent biological treatment in rheumatoid arthritis (RA). Objectives of the study were to investigate the presence of the B7.2 (CD86) molecule and its masking by CTLA4-Ig on cultures of both RA synovial macrophages (RA SM), and of macrophages differentiated from THP-1 cells (M). In addition, the anti-inflammatory effects of CTLA4-Ig on co-cultures of RA SM and M with activated T cells were tested.Methods: All macrophages were co-cultured for 24 hours with activated T cells, without or with CTLA4-Ig (10, 100, 500 \u3bcg/ml for 1 hour, 3 hours and overnight, respectively). Immunofluorescence (IF) staining for B7.2, and an analysis of inflammatory cytokine expression (interleukin (IL) -6, tumor necrosis factor (TNF) \u3b1, IL-1\u3b2, transforming growth factor (TGF) \u3b2) by immunocytochemistry (ICC), western blot (WB) and reverse transcriptase-polymerase chain reaction (RT-PCR) were performed.Results: Macrophages showed intense B7.2 expression. CTLA4-Ig/B7.2 masking was evident for all macrophages, even after only 1 hour of cell culture (range from 10 to 100 \u3bcg/ml). ICC of co-cultures showed a dose-dependent decrease in inflammatory cytokines (P < 0.001 for IL-6, TNF\u3b1, IL-1\u3b2 and TGF\u3b2). Data were confirmed by WB and RT-PCR analysis.Conclusions: Optimal concentrations of CTLA4-Ig for the CTLA4-Ig/B7.2 masking on activated macrophages were identified and were found to induce significant downregulation in the cell production of IL-6, TNF\u3b1, IL1-\u3b2 and TGF\u3b2. In conclusion, macrophages would appear to be a sensitive target for CTLA4-Ig treatment in RA

Androgen metabolism and inhibition of interleukin-1 synthesis in primary cultured human synovial macrophages

The presence of androgen receptors on synovial macrophages in human normal and rheumatoid synovial tissues has been described previously. It is now reported that primary cultured human macrophages obtained from normal and rheumatoid synovia express functional androgen receptors. We have investigated the capacity of cultured macrophages to metabolize androgens and have found that these cells were capable of metabolizing testosterone to the bioactive metabolite dihydrotestosterone. Therefore, macrophages contain the key enzymes of steroidogenesis, in particular the 5α-treductase. Furthermore, interleukin-1β production by primary cultured rheumatoid macrophages was analysed, following exposure to physiological concentrations of testosterone (10−8 M). A significant decrease of IL-1β levels in conditioned media after 24 h (p < 0.05) was observed. It is concluded that androgens may act directly on human macrophages and may interfere with some of their functions via receptor-dependent mechanisms

Myostatin mediates abdominal aortic atherosclerosis progression by inducing vascular smooth muscle cell dysfunction and monocyte recruitment

Myostatin (Mstn) is a skeletal muscle growth inhibitor involved in metabolic disorders and heart fibrosis. In this study we sought to verify whether Mstn is also operative in atherosclerosis of abdominal aorta. In human specimens, Mstn expression was almost absent in normal vessels, became detectable in the media of non-progressive lesions and increased with the severity of the damage. In progressive atherosclerotic lesions, Mstn was present in the media, neointima, plaque shoulder and in infiltrating macrophages. Mstn co-localized with \uce\ub1-smooth muscle actin (\uce\ub1-SMA) staining and with some CD45+ cells, indicating Mstn expression in VSMCs and bloodstream-derived leukocytes. In vitro, Mstn was tested in VSMCs and monocytes. In A7r5 VSMCs, Mstn downregulated proliferation and Smoothelin mRNA, induced cytoskeletal rearrangement, increased migratory rate and MCP-1/CCR2 expression. In monocytes (THP-1 cells and human monocytes), Mstn acted as a chemoattractant and increased the MCP-1-dependent chemotaxis, F-actin, \uce\ub1-SMA, MCP-1 and CCR2 expression; in turn, MCP-1 increased Mstn mRNA. Mstn induced JNK phosphorylation both in VSMCs and monocytes. Our results indicate that Mstn is overexpressed in abdominal aortic wall deterioration, affects VSMCs and monocyte biology and sustains a chronic inflammatory milieu. These findings propose to consider Mstn as a new playmaker in atherosclerosis progression