Cigarette smoke (CS) is associated with chronic obstructive pulmonary disease (COPD) and cancer. However, the underlying pathological mechanisms are not well understood. We recently reported that ...mice exposed to long-term intermittent CS for 3 months developed more severe emphysema and higher incidence of adenocarcinoma than mice exposed to long-term continuous CS for 3 months and long-term continuous CS exposure activated alveolar stem cell proliferation. However, the influence of variations in the CS exposure pattern in alveolar stem cell in unknown. Here, we exposed mice to 3 weeks of continuous or intermittent CS to identify whether different CS exposure patterns would result in differential effects on stem cells and the mechanisms underlying these potential differences.
Female mice expressing GFP in alveolar type 2 (AT2) cells, which are stem cells of the alveolar compartment, were exposed to mainstream CS via nasal inhalation. AT2 cells were collected based on their GFP expression by flow cytometry and co-cultured with fibroblasts in stem cell 3D organoid/colony-forming assays. We compared gene expression profiles of continuous and intermittent CS-exposed AT2 cells using microarray analysis and performed a functional assessment of a differentially expressed gene to confirm its involvement in the process using activator and inhibitor studies.
AT2 cells sorted from intermittent CS-exposed mice formed significantly more colonies compared to those from continuous CS-exposed mice, and both CS-exposed groups formed significantly more colonies when compared to air-exposed cells. Comparative microarray analysis revealed the upregulation of genes related to fatty acid oxidation (FAO) pathways in AT2 cells from intermittent CS-exposed mice. Treatment of intermittent CS-exposed mice with etomoxir, an inhibitor of the FAO regulator Cpt1a, for 5 weeks resulted in a significant suppression of the efficiency of AT2 cell colony formation. In vitro treatment of naïve AT2 cells with a FAO activator and inhibitor further confirmed the relationship between FAO and AT2 stem cell function.
Alveolar stem cell function was more strongly activated by intermittent CS exposure than by continuous CS exposure. We provide evidence that AT2 stem cells respond to intermittent CS exposure by activating stem cell proliferation via the activation of FAO.
To investigate the differing characteristics of limbal niche cells (LNCs) and limbal stromal cells (LSCs) in the maintenance of limbal epithelial stem/progenitor cells in the cornea.
Limbal niche ...cells were obtained from direct dissection of the human corneal limbus, and LSCs were obtained from explant cultures of limbal stromal tissues under the same culture conditions. The resulting cultures were examined for their ability to support the growth of limbal stem/progenitor cells in colony-forming capacity, stratified epithelial cell sheet formation, maintenance of limbal epithelial stem/progenitor cell characteristics, and gene expression levels of factors that supported the limbal epithelial stem/progenitor cells.
The colony-forming efficiency of limbal epithelial stem/progenitor cells in the LNC group (6.57 ± 1.54%) was significantly higher than that in the LSC group (1.43 ± 0.47%). The epithelial cell sheets in the LNC group stratified into four or five layers compared with two or three stratified layers in the LSC group. Staining of both the colonies and the epithelial cell sheets in the LNC group showed a higher intensity of the limbal stem cell marker ΔNp63 than in the LSC group. Moreover, reverse transcription polymerase chain reaction analysis revealed that compared with the common expression of EGF and so on, the LNCs showed a higher expression level of E-cadherin and a lower expression level of neurotrophin-3 (NT3) than the LSCs.
LNCs have a different role compared to LSCs in their ability to support epithelial stem/progenitor cells and epithelial cellular sheet formation.
Carbon fiber reinforced plastics (CFRP) are widely used in aerospace and new energy vehicles due to their high specific strength and flexible design ability. At present, the traditional forming ...process of CFRP curved surface components has problems of low mechanical properties and long processing time. In this paper, a new method of hot gas forming was proposed to obtain CFRP components. By applying high temperature and high-pressure gas on one side of CFRP, the material was forced to deform and solidify at the same time. A special device for hot gas forming was designed and developed. The curing behavior and mechanical properties of original CFRP plates were studied. The main defects and the corresponding control methods of hot gas forming parts were analyzed by forming spherical parts, and the feasibility of the hot gas forming process was verified. Taking the battery cover plate of a new energy vehicle as the research object, the influence of forming temperature, gas pressure, pressurization rate and other process parameters on the mechanical properties of complex CFRP components were analyzed. The mechanism of both strength and efficiency improvement was analyzed. The results showed that with the increasing of gas pressure, the tensile strength and forming efficiency of the CFRP curved components were improved obviously. Under reasonable forming parameters, the tensile strength of the obtained parts was increased by 37%, and the forming efficiency was increased by 58%. The fiber bundles were distributed more evenly and compactly under the hot gas forming. This showed that the use of hot gas forming had good potential in the preparation of high-performance CFRP parts, which was helpful to improve the processing efficiency and forming quality of CFRP curved parts in the aerospace and new energy automotive fields.
In order to improve the forming efficiency of Al–7Si–0.6Mg fabricated by wire and arc additive manufacturing process (WAAM), wire with a diameter of 1.6 mm was selected as the raw material. The ...effect of heat input on the formability, microstructure, and properties of the WAAM alloy was investigated, and the forming model was established. The WAAM alloys were characterized by electronic universal testing, scanning electron microscopy, energy spectrum analysis, and metallographic microscopy. The results show that Al–7Si–0.6Mg alloy has a large processing window under the cold metal transfer (CMT) process, and it can be well formed with a large range of heat input. The secondary dendrite arm spacing and Fe-phase in the as-deposited alloy gradually increase with an increase in heat input, and slight overburning occurs in the heat affected zone at higher heat inputs. After solid solution and aging treatment (T6 heat treatment), the size of α-Al grain and eutectic silicon grain increases with the increase of heat input. Little anisotropy in the mechanical properties is observed except at higher heat inputs. The tensile strength is 354.5 MPa ± 7.5 MPa, yield strength is 310 MPa ± 5.5 MPa, and elongation is 6.3 ± 0.7%.
Background
Mammosphere formation assay has become a versatile tool to quantify the activity of putative breast cancer stem cells in non-adherent in vitro cultures. However, optimizing the suspension ...culture system is crucial to establish mammosphere cultures from primary breast tumors.
Methods
This study aimed at determining the self-renewal and sphere-forming potential of breast cancer stem-like cells derived from human primary invasive ductal carcinoma and normal breast tissue samples, and MCF-7 breast cancer cell line using an optimal suspension culture system. Mammosphere-forming efficiency of the mammospheres generated from the tissue samples and cell line were compared. We evaluated the expression of CD44
+
/CD24
−
/
low
and CD49f
+
/EpCAM
−
/
low
phenotypes in the stem-like cells by flow cytometry. CK-18, CK-19, α-SMA, and EpCAM marker expression was assessed using immunohistochemical staining.
Results
Breast epithelial cells isolated from the three samples formed two-dimensional spheroids in suspension cultures. Interestingly, mammospheres formed from patient-derived primary breast tumors were enriched in breast cancer stem-like cells with the phenotype CD44
+
/CD24
−
/
low
and exhibited a relatively more number of large spheres when compared to the normal breast stem cells. MCF-7-derived SCs were more aggressive and resulted in the formation of a significantly higher number of spheroids. The expression of CK-18/CK-19 and α-SMA/EpCAM proteins was confirmed in breast cancer tissues.
Conclusions
Thus, the use of primary tumor specimens and breast cancer cell lines as suitable models for elucidating the breast cancer stem cell activity was validated using mammosphere culture system.
Improving the forming efficiency at a reasonable cost has been the main challenge in the electromagnetic forming technology. Towards this aim, this paper proposes a simultaneous cost-effective ...double-sheet electromagnetic forming method using single driving coil. In order to highlight the features of the proposed technique, comparison of the performance of five electromagnetic forming models is presented. These models include a no-sheet model, single-sheet stationary model, single-sheet moving model, double-sheet stationary model and double-sheet moving model. For each model, electromagnetic force distribution and forming efficiency of the workpiece are analyzed. Furthermore, the influence of the pulse current width of the driving coil on the electromagnetic forming efficiency of the plate is investigated for all models. Results show that for the same system discharge parameters, electromagnetic forming efficiency of double-sheet is 21.14% whereas the single-sheet electromagnetic forming model only achieves 14.68% efficiency. Thus, the double-sheet electromagnetic forming technology can improve the low forming efficiency of a single-sheet electromagnetic forming method and at the same time, the method can form two workpieces simultaneously which makes it more cost effective than the single-sheet method.
Arsenic toxicity is a current global concern due to its devastating toxic effects on human health. Over several millions of people are exposed to this element on daily basis, mainly through drinking ...water and agricultural pesticides, especially along the Indo-Bangladesh border. Numerous studies have often reflected on arsenic’s deleterious effects on different organs and tissues, including the hematopoietic system. Healthy hematopoiesis is crucial for the homeostasis of functional mature blood cells which are constantly maintained by the bone marrow stem/progenitor cell (HSPC) population. The present study is aimed to understand the hematopoietic cellular status and turnover with special focus on apoptosis and associated alterations in HSPCs in the event of arsenic trioxide exposure in experimental swiss albino mice. The study involves exposure of Swiss albino mice to 10 μg arsenic trioxide/gram of body weight through oral gavage and 5 μg of arsenic trioxide/gram body weight through intraperitoneal injections for a duration of 30 days. The dysregulation in the hematopoietic system was characterized by bone marrow cytochemical analysis, in vitro cellular kinetics study, flow cytometry analysis of hematopoietic populations and component distribution and finally by the apoptosis profile. Upon examination, reduced body weight and reduction in myelopeoxidase (MPO) in the bone marrow cells of arsenic exposed mice were noticed. The diminution in the cell viability supported by apoptosis profile hinted towards hindered hematopoiesis. The in vitro cell culture depicted the catastrophic condition in the hematopoietic compartment of arsenic exposed mice. The flowcytometric analysis revealed the changes in granular population and depletion in CD150
+
and Tie2
+
HSPCs which confirms deregulation in the bone marrow hematopoietic compartment of the arsenic trioxide exposed mice groups. The study presented an overall as well as hematopoiesis specific scenario of arsenic toxicity that would be beneficial for the development of more awareness regarding this common and prevalent hazardous exposure which severely damages the HSPC population, leading to apoptosis and perturbed mature cellular turnover.
The decline of tissue regenerative potential of skin and hair is a hallmark of physiological ageing and may be associated with age‐related changes in tissue‐specific stem cells and/or their ...environment. Human hair follicles (hHF) contain keratinocytes having the property of stem cells such as clonogenic potential. Growth capacity of hHF keratinocytes shows that most of the colony‐forming cells are classified as holoclones, meroclones or paraclones when analysed in a clonal assay (Cell, Volume 76, page 1063). Despite the well‐known impact of ageing on human hair growth, little is known about changes in hHF keratinocyte clonogenic potential with age. This study aimed at assessing the clone‐forming efficiency (CFE) of hHF keratinocytes from three age groups of human donors. It demonstrates that ageing affects hHF keratinocyte CFE.
The low efficiency of the electromagnetic forming is one of the obstacles for the advancement of this technology. Aiming at solving this issue, this paper presents a double tube-task electromagnetic ...forming technology method by employing a single driving coil to achieve tube compression and expansion at the same time. On the basis of electromagnetic forming principles and the law of energy conversion, this paper presents a new electromagnetic forming model for double tubes. The magnetic flux density distribution, electromagnetic force distribution and forming efficiency of the tube are analyzed and the effect of the equivalent pulse width of the driving coil current on the forming efficiency is investigated. Results show that in order to maintain the same plastic strain energy of the tube, the initial discharge energy required by the proposed double tube model is 25 kJ which is smaller than that required by a traditional single tube model (33.58kJ) and the efficiency can be improved by about 34.3%. The double tube model attains the maximum forming efficiency near the optimal current pulse width and can improve the low efficiency of traditional electromagnetic forming to a certain extent and provide more possibilities for this technological process.
PDF
