In this study, an extended calculation method for the determination of the water profiles in oil‐treated skin is proposed, which is based on the calculation of the ratio between the Raman band intensities of water (3350‐3550 cm?1) and keratin Amide I at 1650 cm?1. The proposed method is compared with the conventional method based on the ratio of the Raman band intensities of water (3350‐3550 cm?1) and keratin at 2930 cm?1. The conventional method creates artifacts in the depth profiles of the water concentration in oil‐treated skin, showing a lower amount of water in the upper and intermediate layers of the stratum corneum, which is due to the superposition of oil‐ and keratin‐related Raman bands at 2930 cm?1. The proposed extended method shows no artifacts and has the potential to determine the water depth profiles after topical application of formulations on the skin. 相似文献
Myotonic Dystrophy type 1 (DM1) is the most common form of muscular dystrophy in adults, characterized by a variety of multisystemic features and associated with cardiac anomalies. Among cardiac phenomena, conduction defects, ventricular arrhythmias, and dilated cardiomyopathy represent the main cause of sudden death in DM1 patients. Patient‐specific induced pluripotent stem cell‐derived cardiomyocytes (hiPSC‐CMs) represent a powerful in vitro model for molecular, biochemical, and physiological studies of disease in the target cells. Here, we used an Atomic Force Microscope (AFM) to measure the beating profiles of a large number of cells, organized in CM clusters (Beating Bodies, BBs), obtained from wild type (WT) and DM1 patients. We monitored the evolution over time of the frequency and intensity of the beating. We determined the variations between different BBs and over various areas of a single BB, caused by morphological and biomechanical variations. We exploited the AFM tip to apply a controlled force over the BBs, to carefully assess the biomechanical reaction of the different cell clusters over time, both in terms of beating frequency and intensity. Our measurements demonstrated differences between the WT and DM1 clusters highlighting, for the DM1 samples, an instability which was not observed in WT cells. We measured differences in the cellular response to the applied mechanical stimulus in terms of beating synchronicity over time and cell tenacity, which are in good agreement with the cellular behavior in vivo. Overall, the combination of hiPSC‐CMs with AFM characterization can become a new tool to study the collective movements of cell clusters in different conditions and can be extended to the characterization of the BB response to chemical and pharmacological stimuli. 相似文献
The cartilage is composed of chondrocytes embedded in a matrix of collagen fibrils interspersed within a network of proteoglycans and is constantly exposed to biomechanical forces during normal joint movement. Characterization of the surface morphology, cytoskeletal structure, adherance and elastic properties of these mechanosensitive cells are crucial in understanding the effects of mechanical forces around a cell and how a cell responds to changes in its physical environment. In this work, we employed the atomic force microscope (AFM) to image cultured chondrocytes before and after subjecting them to mechanical forces in the presence or absence of interleukin-1β to mimic inflammatory conditions. Nanoscale imaging and quantitative measurements from AFM data revealed that there are distinct changes in cell-surface topology and cytoskeleton arrangement in the cells following treatment with mechanical forces, IL-1β or both. Our findings for the first time demonstrate that cultured chondrocytes are amenable to high-resolution AFM imaging and dynamic tensile forces may help overcome the effect of inflammatory factors on chondrocyte response. 相似文献
The anuran remodels the larval epidermis into the adult one during metamorphosis. Larval and adult epidermal cells of the bullfrog were characterized by determining the presence of huge cytoplasmic keratin bundles and the expression profiles of specific marker genes, namely colalpha1 (collagen alpha1 (I)), rlk (larval keratin) and rak (adult keratin). We identified four types of epidermal basal cells: (i) basal skein cells that have keratin bundles and express colalpha1 and rlk; (ii) rak+-basal skein cells that have keratin bundles and express colalpha1, rlk, and rak; (iii) larval basal cells that express rlk and rak; and (iv) adult basal cells that express rak. These traits suggested that these basal cells are on the same lineage in which basal skein cells are the original progenitor cells that consecutively differentiate into rak+-basal skein cells into larval basal cells, and finally into adult basal cells. To directly verify the differentiation potential of larval basal cells into adult ones, the mono-layered epidermis composed of larval basal cells was cultured in the presence of aldosterone and thyroid hormone. In this culture, larval basal cells differentiated into adult basal cells that reconstituted the adult epidermis. Thus, it was concluded that larval basal cells are the direct progenitor cells of the adult epidermal stem cells. 相似文献
We investigated the relationship between induction of radio-adaptive response and cell death in mouse normal and neoplastic
epidermal cells. Mouse normal primary keratinocytes (PK), cancer-prone cells [v-rasHa-transfected mouse keratinocytes (ras-PK), and line 308 cells (mouse skin papilloma cells which have activatedrasHa gene with A-to-T transversion at codon 61) were primed with a low dose of γ-rays (0.01 Gy), and were challenged with a high
dose (4 Gy) after a 4 or 7 h interval. The induction of cell death in PK was 2–10 times higher and was also more rapid in
PK than in ras-PK or 308 cells. Low-dose pretreatment with a 4 h interval decreased cell death, and this adaptive response
was prominent in PK, whereas it was less obvious in the cases of ras-PK and 308 cells. The response of each protein kinase
C (PKC) isozymes to high-dose radiation, especially PKCα, PKCδ, PKCε, and PKCη, were different between the normal andras oncogene-activated neoplastic keratinocytes; translocation of these isozymes to membrane occurred more rapidly in normal
than in neoplastic cells. Furthermore, low-dose pretreatment did not induce the translocation of PKCδ in PK significantly
more than in ras-PK and 308. Thus, the difference in the induction of radio-adaptive responses between mouse normal and neoplastic
epidermal cells reflects difference in the rapidity of cell death, and responsiveness of PKC may affect this adaptive response.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
Following a series of eccentric contractions, that is stretching of the muscle while generating active tension, the length-tension
relationship of isolated amphibian muscle has been shown to shift towards longer muscle lengths (Katz 1939; Wood et al. 1993).
Here we report observations of electrically stimulated ankle extensor muscles of nine human subjects, demonstrating a similar
shift in optimum angle for torque generation [3.9 (1.5)°] following exercise on an inclined treadmill that involved eccentric
contractions in one leg. (All values are means with the SEMs in parentheses.) The shift in the unexercised, control leg was
significantly less [mean 0.4 (0.7)°P < 0.05]. Correlated with this shift was a drop in torque [25.1 (5.6)% for the experimental leg; 1.6 (0.7)% for the control
leg, P < 0.002]. Optimum angles returned to pre-exercise values by 2 days post-exercise, while torque took a week to recover. A
similar shift in optimum length [12 (1.3)% of rest length] was obtained for five toad (Bufo marinus) sartorius muscles subjected to 25 eccentric contractions. Isometrically contracted control muscles showed a smaller shift
[3.5 (1.6)%, n = 5]. Accompanying the shift was a drop in tension of 46 (3)% after the eccentric contractions [control isometric, 23 (6)%,
P < 0.0001]. By 5 h after the eccentric contractions the shift had returned to control values, while tension had not recovered.
When viewed with an electron microscope, sartorius muscles fixed immediately after the eccentric contractions exhibited many
small, and a few larger, regions of myofilament disruption. In muscles fixed 5 h after the contractions, no small regions
of disruption were visible, and the number of large regions was no greater than in those muscles fixed immediately after the
eccentric contractions. These disruptions are interpreted as the cause of the shift in length-tension relationship.
Accepted: 9 January 1997 相似文献
Adipose‐derived stem cells (ADSCs) are a subset of mesenchymal stem cells (MSCs), which have promised a vast therapeutic potential in tissue regeneration. Recent studies have demonstrated that combining stem cells with mechanical stretch may strengthen the efficacy of regenerative therapies. However, the exact influences of mechanical stretch on MSCs still remain inconclusive. In this study, human ADSCs (hADSCs) were applied cyclic stretch stimulation under an in vitro stretching model for designated duration. We found that mechanical stretch significantly promoted the proliferation, adhesion and migration of hADSCs, suppressing cellular apoptosis and increasing the production of pro‐healing cytokines. For differentiation of hADSCs, mechanical stretch inhibited adipogenesis, but enhanced osteogenesis. Long‐term stretch could promote ageing of hADSCs, but did not alter the cell size and typical immunophenotypic characteristics. Furthermore, we revealed that PI3K/AKT and MAPK pathways might participate in the effects of mechanical stretch on the biological characteristics of hADSCs. Taken together, mechanical stretch is an effective strategy for enhancing stem cell behaviour and regulating stem cell fate. The synergy between hADSCs and mechanical stretch would most likely facilitate tissue regeneration and promote the development of stem cell therapy. 相似文献
The skin is a highly complex organ, responsible for sensation, protection against the environment (pollutants, foreign proteins, infection) and thereby linked to the immune and sensory systems in the neuro‐immuno‐cutaneous (NIC) system. Cutaneous innervation is a key part of the peripheral nervous system; therefore, the skin should be considered a sensory organ and an important part of the central nervous system, an ‘active interface’ and the first connection of the body to the outside world. Peripheral nerves are a complex class of neurons within these systems, subsets of functions are conducted, including mechanoreception, nociception and thermoception. Epidermal and dermal cells produce signalling factors (such as cytokines or growth factors), neurites influence skin cells (such as via neuropeptides), and peripheral nerves have a role in both early and late stages of the inflammatory response. One way this is achieved, specifically in the cutaneous system, is through neuropeptide release and signalling, especially via substance P (SP), neuropeptide Y (NPY) and nerve growth factor (NGF). Cutaneous, neuronal and immune cells play a central role in many conditions, including psoriasis, atopic dermatitis, vitiligo, UV‐induced immunosuppression, herpes and lymphomas. Therefore, it is critical to understand the connections and interplay between the peripheral nervous system and the skin and immune systems, the NIC system. Relevant in vitro tissue models based on human skin equivalents can be used to gain insight and to address impact across research and clinical needs. 相似文献
Lipopolysaccharide (LPS) on gram‐negative bacterial outer membranes is the first target for antimicrobial agents, due to their spatial proximity to outer environments of microorganisms. To develop antibacterial compounds with high specificity for LPS binding, the understanding of the molecular nature and their mode of recognition is of key importance. In this study, atomic force microscopy (AFM) and single molecular force spectroscopy were used to characterize the effects of antibiotic polymyxin B (PMB) to the bacterial membrane at the nanoscale. Isolated LPS layer and the intact bacterial membrane were examined with respect to morphological changes at different concentrations of PMB. Our results revealed that 3 hours of 10 μg/mL of PMB exposure caused the highest roughness changes on intact bacterial surfaces, arising from the direct binding of PMB to LPS on the bacterial membrane. Single molecular force spectroscopy was used to probe specific interaction forces between the isolated LPS layer and PMB coupled to the AFM tip. A short range interaction regime mediated by electrostatic forces was visible. Unbinding forces between isolated LPS and PMB were about 30 pN at a retraction velocity of 500 nm/s. We further investigated the effects of the polycationic peptide PMB on bacterial outer membranes and monitored its influences on the deterioration of the bacterial membrane structure. Polymyxin B binding led to rougher appearances and wrinkles on the outer membranes surface, which may finally lead to lethal membrane damage of bacteria. Our studies indicate the potential of AFM for applications in pathogen recognition and nano‐resolution approaches in microbiology. 相似文献
Ex‐vivo confocal laser scanning microscopy (CLSM) is an emerging diagnostic tool allowing fast and easy microscopic tissue examination. The first generation of ex‐vivo devices have already shown promising results in the ex‐vivo evaluation of basal cell carcinoma compared to Mohs surgery. Nevertheless, for the diagnostics of pathological skin lesions the knowledge of normal skin features is essential. Therefore we examined 50 samples of healthy skin from various donor sites including head and neck (n = 25), trunk (n = 10), upper (n = 10) and lower extremities (n = 5) using a new generation ex‐vivo CLSM device offering three different laser wavelengths and compared the findings to the corresponding histological sections. In correlation with the histopathology we identified different layers of the epidermis, differentiated keratinocytes from melanocytes and described in detail skin appendages including hair follicle, sebaceous and sweat glands. Furthermore, structures of the dermis and subcutis were illustrated. Additionally, artefacts and pitfalls occurring with the use of ex‐vivo CLSM have been documented. The study offers an overview of the main ex‐vivo CLSM skin characteristics in comparison to the standard histological examination and helps to recognize and avoid common artefacts.
Anatomy of a hair follicle in the reflectance mode (RM) CLSM, fluorescence mode (FM) CLSM and in a routine hematoxylin‐eosin stained histological section (H). 相似文献
This note reports observations of the change of stiffness of human mesenchymal stem cells (hMSCs) with the progress of cell death as measured by AFM. hMSC with impaired membrane, dead and viable cells were labelled with Annexin V and Propidium Iodide after 24 h cold storage, followed by AFM measurement and Young's modulus of cells was derived. Viable hMSCs have a Young's modulus (E) in the range of 0.81–1.13 kPa and consistent measurement was observed when different measurement locations were chosen. E of cells with partially impaired membrane was 0.69±0.17 kPa or in the range of 2.04–4.74 kPa, depending upon the measurement locations. With the loss of membrane integrity, though there was no variation on measured E between different locations, a mixed picture of cell stiffness was observed as indicated by cells with E as low as 0.09±0.03 kPa, in a mid-range of 4.62±0.67 kPa, and the highest of up to 48.98±19.80 kPa. With the progress of cell death, the highest stiffness was noticed for cells showing a more granular appearance; also the lowest stiffness for cells with vacuole appearance. Findings from this study indicate that cell stiffness is significantly altered with the progress of cell death. 相似文献
The influence of topically applied tap water on the mechanical properties of human skin was studied in vivo by applying tap water to the ventral aspect of the forearms of 18 healthy volunteers for 10 or 20 minutes and then measuring distensibility, elastic retraction, and hysteresis. Significant increases in distensibility, resilient distensibility, and hysteresis were noted after 20 minutes of soaking. Most of these findings were already apparent after 10 minutes. This study shows that the epidermis plays a significant role in determining the mechanical properties of human skin. Possible practical implications of superficial skin hydration for plastic surgery such as tissue expansion and larger excisions are briefly discussed. 相似文献