Unsteady Flow Regimes in a T-Shaped Micromixer: Mixing and Characteristic Frequencies

Experiments and direct numerical simulations are used jointly to study the asymmetric and symmetric time-periodic regimes occurring in a T-shaped micro mixer for larger Reynolds numbers than those of steady regimes. The first is characterized by a large mixing degree, whereas the flow in the second regime Always exhibits a nearly double mirror symmetry in the mixing channel, which strongly hampers mixing. The characteristic nondimensional frequency, calculated using the hydraulic diameter of the mixing channel and the bulk velocity, augments with the Reynolds number in both periodic regimes, but a large discontinuity is observed at the transition between the two regimes. A detailed description of the main flow features is given to provide a physical explanation on the Strouhal number variation. The present analysis can be exploited in practice to design active control strategies, e.g., by exciting the flow at the frequencies typical of the asymmetric unsteady regime

ABCG2, a novel antigen to sort luminal progenitors of BRCA1- breast cancer cells.

International audienceINTRODUCTION: Tumor-initiating cells (TICs), aka "cancer stem cells", are believed to fuel tumors and to sustain therapy resistance and systemic metastasis. Breast cancer is the first human carcinoma in which a subpopulation of cells displaying a specific CD44+/CD24-/low/ESA+ antigenic phenotype was found to have TIC properties. However, CD44+/CD24-/low/ESA+ is not a universal marker phenotype of TICs in all breast cancer subtypes. The aim of this study was to identify novel antigens with which to isolate the TIC population of the basal-A/basal-like breast cancer cell lines. METHODS: We used polychromatic flow-cytometry to characterize the cell surface of several breast cancer cell lines that may represent different tumor molecular subtypes. We next used fluorescence-activated cell sorting to isolate the cell subpopulations of interest from the cell lines. Finally, we explored the stem-like and tumorigenic properties of the sorted cell subpopulations using complementary in vitro and in vivo approaches: mammosphere formation assays, soft-agar colony assays, and tumorigenic assays in NOD/SCID mice. RESULTS: The CD44+/CD24+ subpopulation of the BRCA1-mutated basal-A/basal-like cell line HCC1937 is enriched in several stemness markers, including the ABCG2 transporter (i.e., the CD338 antigen). Consistently, CD338-expressing cells were also enriched in CD24 expression, suggesting that coexpression of these two antigenic markers may segregate TICs in this cell line. In support of ABCG2 expression in TICs, culturing of HCC1937 cells in ultra-low adherent conditions to enrich them in precursor/stem-cells resulted in an increase in CD338-expressing cells. Furthermore, CD338-expressing cells, unlike their CD338-negative counterparts, displayed stemness and transformation potential, as assessed in mammosphere and colony formation assays. Lastly, CD338-expressing cells cultured in ultra-low adherent conditions maintained the expression of CD326/EpCAM and CD49f/α6-integrin, which is a combination of antigens previously assigned to luminal progenitors. CONCLUSION: Collectively, our data suggest that CD338 expression is specific to the tumor-initiating luminal progenitor subpopulation of BRCA1-mutated cells and is a novel antigen with which to sort this subpopulation

shear modulus of masonry walls a critical review

Abstract In the assessment of seismic performance of masonry buildings, the proper definition of mechanical parameters of masonry, the shear modulus in particular, is a critical issue. Moreover, considering that existing buildings are characterized by several masonry types, depending on the material as well as on the texture, mechanical parameters can vary in a very wide range, also because they depend on many other parameters and in particular on the integrity of the walls and on the stress level. Although the in situ or laboratory experimental evaluation of the G modulus has been the subject of a wide literature concerning flat jacks, diagonal and single compression and shear-compression test results, its outcomes are often contradictory. In effect, values given by different studies often differ significantly, even for the same class of masonry. Since the intrinsic scattering of the parameter is not sufficient by itself to justify the huge variability of the results, a critical discussion of the results as well as of the individual test arrangements is necessary to make the background more reliable, also in view of better addressing further studies- A huge database has been setup combining masonry test results available in the relevant scientific literature with the test results obtained in the framework of the in situ experimental campaign carried out by the authors for the assessment of seismic vulnerability of masonry school buildings in the Municipality of Florence. The analysis of the database underlines that values of the shear modulus G, which is a fundamental parameter for the definition of capacity curve for walls commonly used in non-linear static analysis, are extremely scattered. Testing methodology and arrangement are discussed and a possible procedure is proposed to arrive to sounder estimations of relevant mechanical parameter of existing building masonry

Extended flow cytometry characterization of normal bone marrow progenitor cells by simultaneous detection of aldehyde dehydrogenase and early hematopoietic antigens: implication for erythroid differentiation studies

<p>Abstract</p> <p>Background</p> <p>Aldehyde dehydrogenase (ALDH) is a cytosolic enzyme highly expressed in hematopoietic precursors from cord blood and granulocyte-colony stimulating factor mobilized peripheral blood, as well as in bone marrow from patients with acute myeloblastic leukemia. As regards human normal bone marrow, detailed characterization of ALDH⁺cells has been addressed by one single study (Gentry <it>et al</it>, 2007). The goal of our work was to provide new information about the dissection of normal bone marrow progenitor cells based upon the simultaneous detection by flow cytometry of ALDH and early hematopoietic antigens, with particular attention to the expression of ALDH on erythroid precursors. To this aim, we used three kinds of approach: i) multidimensional analytical flow cytometry, detecting ALDH and early hematopoietic antigens in normal bone marrow; ii) fluorescence activated cell sorting of distinct subpopulations of progenitor cells, followed by <it>in vitro </it>induction of erythroid differentiation; iii) detection of ALDH⁺cellular subsets in bone marrow from pure red cell aplasia patients.</p> <p>Results</p> <p>In normal bone marrow, we identified three populations of cells, namely ALDH⁺CD34⁺, ALDH^-CD34⁺and ALDH⁺CD34^-(median percentages were 0.52, 0.53 and 0.57, respectively). As compared to ALDH^-CD34⁺cells, ALDH⁺CD34⁺cells expressed the phenotypic profile of primitive hematopoietic progenitor cells, with brighter expression of CD117 and CD133, accompanied by lower display of CD38 and CD45RA. Of interest, ALDH⁺CD34^-population disclosed a straightforward erythroid commitment, on the basis of three orders of evidences. First of all, ALDH⁺CD34^-cells showed a CD71^bright, CD105⁺, CD45^-phenotype. Secondly, induction of differentiation experiments evidenced a clear-cut expression of glycophorin A (CD235a). Finally, ALDH⁺CD34^-precursors were not detectable in patients with pure red cell aplasia (PRCA).</p> <p>Conclusion</p> <p>Our study, comparing surface antigen expression of ALDH⁺/CD34⁺, ALDH^-/CD34⁺and ALDH⁺/CD34^-progenitor cell subsets in human bone marrow, clearly indicated that ALDH⁺CD34^-cells are mainly committed towards erythropoiesis. To the best of our knowledge this finding is new and could be useful for basic studies about normal erythropoietic differentiation as well as for enabling the employment of ALDH as a red cell marker in polychromatic flow cytometry characterization of bone marrow from patients with aplastic anemia and myelodysplasia.</p

The percentage of CD133+ cells in human colorectal cancer cell lines is influenced by Mycoplasma hyorhinis infection

<p>Abstract</p> <p>Background</p> <p><it>Mollicutes </it>contamination is recognized to be a critical issue for the cultivation of continuous cell lines. In this work we characterized the effect of <it>Mycoplasma hyorhinis </it>contamination on CD133 expression in human colon cancer cell lines.</p> <p>Methods</p> <p>MycoAlert^®and mycoplasma agar culture were used to detect mycoplasma contamination on GEO, SW480 and HT-29 cell lines. Restriction fragment length polymorphism assay was used to determine mycoplasma species. All cellular models were decontaminated by the use of a specific antibiotic panel (Enrofloxacin, Ciprofloxacin, BM Cyclin 1 and 2, Mycoplasma Removal Agent and MycoZap^®). The percentage of CD133 positive cells was analyzed by flow cytometry on GEO, SW480 and HT-29 cell lines, before and after <it>Mycoplasma hyorhinis </it>eradication.</p> <p>Results</p> <p><it>Mycoplasma hyorhinis </it>infected colon cancer cell lines showed an increased percentage of CD133+ cells as compared to the same cell lines rendered mycoplasma-free by effective exposure to antibiotic treatment. The percentage of CD133 positive cells increased again when mycoplasma negative cells were re-infected by <it>Mycoplasma hyorhinis</it>.</p> <p>Conclusions</p> <p><it>Mycoplasma hyorhinis </it>infection has an important role on the quality of cultured human colon cancer cell lines giving a false positive increase of cancer stem cells fraction characterized by CD133 expression. Possible explanations are (i) the direct involvement of Mycoplasma on CD133 expression or (ii) the selective pressure on a subpopulation of cells characterized by constitutive CD133 expression.</p> <p>In keeping with United Kingdom Coordinating Committee on Cancer Research (UKCCCR) guidelines, the present data indicate the mandatory prerequisite, for investigators involved in human colon cancer research area, of employing mycoplasma-free cell lines in order to avoid the production of non-reproducible or even false data.</p

Direct analysis of thymic function in children with Down's syndrome

BACKGROUND: Down's syndrome (DS) is characterized by several immunological defects, especially regarding T cell compartment. DS is considered the best example of accelerated ageing in humans. Direct observations of the thymus have shown that in DS this organ undergoes severe histological and morphological changes. However, no data on its capacity to generate T cells are present in the literature. Here, using a new technology based upon real time PCR, we have investigated the capacity of the thymus to produce and release newly generated T lymphocytes (the so called "recent thymic emigrants", RTE) in children with DS. METHODS: We studied 8 children affected by DS, aged 2–7 years, compared with 8 age- and sex-matched healthy controls. Flow cytometry was used to determine different lymphocytes subsets. Real time PCR with the Taqman system was used to quantify the amount of RTE, i.e. peripheral blood lymphocytes that express the T cell receptor rearrangement excision circles (TREC). RESULTS: In comparison with control children, those with DS had a significant lower number of TREC+ peripheral blood cells. Moreover, in DS children but not in controls, a strong negative correlation between age and the levels of TREC+ cells was found. CONCLUSIONS: The direct measure of thymic output indicates that the impairment of the organ results in a reduced production of newly generated T cells. This observation could suggest that cytokines able to modulate thymic function, such as interleukins, could be useful to improve the functionality of the organ and to treat the immunodeficiency present in DS subjects

Longitudinal changes of SARA scale in Friedreich ataxia: Strong influence of baseline score and age at onset

BACKGROUND: The Scale for Assessment and Rating of Ataxia (SARA) is widely used in different types of ataxias and has been chosen as the primary outcome measure in the European natural history study for Friedreich ataxia (FA). METHODS: To assess distribution and longitudinal changes of SARA scores and its single items, we analyzed SARA scores of 502 patients with typical-onset FA (<25 years) participating in the 4-year prospective European FA Consortium for Translational Studies (EFACTS). Pattern of disease progression was determined using linear mixed-effects regression models. The chosen statistical model was re-fitted in order to estimate parameters and predict disease progression. Median time-to-change and rate of score progression were estimated using the Kaplan-Meier method and weighted linear regression models, respectively. RESULTS: SARA score at study enrollment and age at onset were the major predictive factors of total score progression during the 4-year follow-up. To a less extent, age at evaluation also influenced the speed of SARA progression, while disease duration did not improve the prediction of the statistical model. Temporal dynamics of total SARA and items showed a great variability in the speed of score increase during disease progression. Gait item had the highest annual progression rate, with median time for one-point score increase of 1 to 2 years. INTERPRETATION: Analyses of statistical properties of SARA suggest a variable sensitivity of the scale at different disease stages, and provide important information for population selection and result interpretation in future clinical trials

Humoral and cellular immune response elicited by mRNA vaccination against SARS-CoV-2 in people living with HIV (PLWH) receiving antiretroviral therapy (ART) according with current CD4 T-lymphocyte count

BACKGROUND: Data on SARS-CoV-2 vaccine immunogenicity in PLWH are currently limited. Aim of the study was to investigate immunogenicity according to current CD4 T-cell count. METHODS: PLWH on ART attending a SARS-CoV-2 vaccination program, were included in a prospective immunogenicity evaluation after receiving BNT162b2 or mRNA-1273. Participants were stratified by current CD4 T-cell count (poor CD4 recovery, PCDR: 500/mm^{3}). RBD-binding IgG, SARS-CoV-2 neutralizing antibodies (nAbs) and IFN-γ release were measured. As control group, HIV-negative healthcare workers (HCWs) were used. FINDINGS: Among 166 PLWH after 1 month from the second dose, detectable RBD-binding IgG were elicited in 86.7% of PCDR, 100% of ICDR, 98.7% of HCDR, and a neutralizing titre ≥1:10 elicited in 70.0%, 88.2% and 93.1%, respectively. Compared to HCDR, all immune response parameters were significantly lower in PCDR. After adjusting for confounders, current CD4 T-cell 500 cell/mm^{3} and HIV-negative controls. A decreased RBD-binding antibody response than HCWs was also observed in PLWH with CD4 T-cell 200-500/mm^{3}, whereas immune response elicited in PLWH with a CD4 T-cell >500/mm^{}3 was comparable to HIV-negative population

At the intersection of cultural and natural heritage: Distribution and conservation of the type localities of Italian endemic vascular plants

We conducted a GIS spatial analysis with the aim of providing the first quantitative large-scale overview of the distribution patterns of 1536 type localities (loci classici) of 1216 Italian endemic vascular plants and their relationship with a set of descriptive variables. Whereas some variables were used to model the presence-absence distribution patterns of the type localities for the whole set of endemics as well as for the subset of narrow endemics, others (e.g., presence inside or outside protected areas and Italian Important Plant Areas) were considered with the purpose of assessing potential assets or risks for conservation. The largest number of type localities was found within the Mediterranean biogeographic region (1134), followed by the Alpine region (306) and Continental region (96). A total of 670 locations are located on islands, whereas 866 are located on the Italian mainland (139 and 124 in the case of narrow endemics, respectively). A large number of type localities are located in mountainous areas and along the coastline, which can be seen as a potential risk for conservation. On the contrary, we detected a positive correlation with the distance from roads, which might be considered to be an asset. Importantly, 1030 type localities fall inside protected areas, whereas 506 localities fall outside protected areas, with 259 of these unprotected localities on islands. We propose considering the results of the analysis of the distribution of type localities of Italian endemics to be a strategic tool for conservation planning and resource management. Application of plant micro-reserves and integration of diverse legislation tools are suggested to strengthen efforts and increase conservation success