14,071 research outputs found
Merkel
No full textPlat of the town of Merkel, Texas which appears to have been part of a survey for the Texas & Pacific Railway Company. The various blocks of the town are divided to show the property lines. A legal statement at the top of the page asserts that the map is an accurate representation of the town and is signed by the land commissioner for the railway company. An inset in the upper-left corner shows the Grimes County School land. The map appears to have been sketched on a page from a ledger. Scale 1:3,600 (This map, Scale 1"=300', Drawn on Record 1"=200'
Promoter activity of Merkel cell Polyomavirus variants in human dermal fibroblasts and a Merkel cell carcinoma cell line.
No full textBackground - Merkel cell polyomavirus (MCPyV) is a human polyomavirus that establishes a life-long harmless infection in most individuals, with dermal fibroblasts believed to be the natural host cell. However, this virus is the major cause of Merkel cell carcinoma (MCC), an aggressive skin cancer. Several MCPyV variants with polymorphism in their promoter region have been isolated, but it is not known whether these differences affect the biological properties of the virus.
Methods - Using transient transfection studies in human dermal fibroblasts and the MCC cell line MCC13, we compared the transcription activity of the early and late promoters of the most commonly described non-coding control region MCPyV variant and six other isolates containing specific mutation patterns.
Results - Both the early and late promoters were significantly stronger in human dermal fibroblasts compared with MCC13 cells, and a different promoter strength between the MCPyV variants was observed. The expression of full-length large T-antigen, a viral protein that regulates early and late promoter activity, inhibited early and late promoter activities in both cell lines. Nonetheless, a truncated large T-antigen, which is expressed in virus-positive MCCs, stimulated the activity of its cognate promoter.
Conclusion - The promoter activities of all MCPyV variants tested was stronger in human dermal fibroblasts, a cell line that supports viral replication, than in MCC13 cells, which are not permissive for MCPyV. Truncated large T-antigen, but not full-length large T-antigen stimulated viral promoter activity. Whether, the difference in promoter strength and regulation by large T-antigen may affect the replication and tumorigenic properties of the virus remains to be determined
CCL17/TARC and CCR4 expression in Merkel cell carcinoma
No full textMerkel cell carcinoma (MCC) is a rare, highly aggressive neuroendocrine skin cancer. In more than 80% of the cases, Merkel cell polyomavirus (MCPyV) is a causal factor. The oncogenic potential of MCPyV is mediated through its viral oncoproteins, large T antigen (LT) and small t antigen (sT). To investigate the role of cytokines in MCC, a PCR array analysis for genes encoding inflammatory cytokines and receptors was performed on MCPyV-negative and MCPyV-positive MCC cell lines, respectively. We detected an increased expression of CCL17/TARC in the MCPyV-positive MKL2 cell line compared to the MCPyV-negative MCC13 cell line. Transfection studies in MCC13 cells with LT expression plasmid, and a luciferase reporter plasmid containing the CCL17/TARC promoter, exhibited stimulated promoter activity. Interestingly, the ectopic expression of CCL17/TARC upregulated MCPyV early and late promoter activities in MCC13 cells. Furthermore, recombinant CCL17/TARC activated both the mitogen-activated protein kinase and the NF-κB pathways. Finally, immunohistochemical staining on human MCC tissues showed a strong staining of CCL17/TARC and its receptor CCR4 in both LT-positive and -negative MCC. Taken together, CCL17/TARC and CCR4 may be a potential target in MCC therapy providing MCC patients with a better overall survival outcome
Immunohistochemical characterization of normal canine Merkel cells
No full textCutaneous Merkel cells (MCs) have been well documented in humans, but less in other mammals. In dogs, there are only a few references about immunohistochemical characterization of MCs. We present the immunohistochemical profile of MCs in the dog for the most reliable antibodies used in human medicine. Tissue samples from several locations were obtained from five adult dogs of both sexes and different age and breed, fixed in 10% buffered formalin, embedded in paraffin wax and cut in 3-mum tissue sections. The ABC method was used with different poly- and monoclonal antibodies. Positive immunoreaction was found in MCs of hair follicles, skin and mucosae of several locations in each dog studied for anticytokeratins 8, 18 and 20, anti-neurofilaments, anti-chromogranin A, anti-neuron-specific enolase, and anti-synaptophysin. Immunoreaction was always cytoplasmic with differences in intensity, pattern of intracytoplasmic distribution and reaction type. Other cytokeratins, anti-S100 protein, anti-vimentin and anti-glial fibrillary acid protein were absent in canine normal MCs.5549
Dissociation, quantification and culture of normal human merkel cells among epidermal cell populations derived from glabrous and hairy skin sites
No full textMerkel cells constitute a unique population that remains difficult to characterize in human skin because of their scarcity. Our aim was to develop tools for the study of Merkel cells in vitro. As a first step, we evaluated the possibility of harvesting human Merkel cells with the two-step extraction method that is widely used to extract and culture keratinocytes. Merkel cells were identified in the epithelial portion of hairy or glabrous skin biopsies by keratin (K)18 and K20 labeling. The totality of cutaneous epithelial cells were isolated from either hairy or glabrous skin biopsies following enzymatic dissociation of both the epidermis and the hair follicles. Flow cytometry was performed to quantify the small Merkel cell population. The analysis revealed that K18-labeled cells represented between 4.0 and 7.6% of freshly dissociated basal epidermal cells. No significant differences were seen between samples derived from glabrous palmar and hairy anatomic sites from children and adults, respectively. We also reported on the presence of Merkel cells in primary and first subcultures of human epidermal cells. The next step will be to enrich the isolated human Merkel cells and improve their culture conditions. An amplification of the number of Merkel cells will allow further studies to unravel long-standing questions regarding their origin, proliferative capacity, and functions in cutaneous biolog
Expression of developmentally regulated transcription factors in Merkel cell carcinoma
No full textWe have examined a number of developmentally regulated transcription factors for expression in Merkel cells and MCC cell lines and demonstrated that their expression patterns may be prognostic in MCC. We have shown that human Merkel cells from adult scalp hair follicle and from neonatal foreskin epidermal sheets express Brn-3c and HATH1. In addition, results demonstrate that the novel Merkel binding activity complex MNF contains Brn-3c. Moreover, Classic lines which retain neuroendocrine phenotype, are slow growing in culture, grow in suspension and are thought to be less aggressive, retain Brn-2, Brn-3c and HATH1 expression, whereas Variant suspension lines which no longer express NE markers retain Brn-2 and Brn-3c expression, but lack HATH1. Further, Type IV Variant lines which grow as adherent monolayers have shorter doubling times, are more radiation- resistant and have higher cloning efficiencies in soft agar, all thought to be indicative of aggressive tumours, have reduced or no Brn-2 proteins and lack expression of Brn-3c and HATH1 transcription factors.No Full Tex
Untersuchungen über die Irritabilität und Rhythmicität des nervenhaltigen und nervenlosen Froschherzens: Mit Zusätzen von F. Merkel und A. Thierfelder
No full textUNTERSUCHUNGEN ÜBER DIE IRRITABILITÄT UND RHYTHMICITÄT DES NERVENHALTIGEN UND NERVENLOSEN FROSCHHERZENS: MIT ZUSÄTZEN VON F. MERKEL UND A. THIERFELDER
Untersuchungen über die Irritabilität und Rhythmicität des nervenhaltigen und nervenlosen Froschherzens: Mit Zusätzen von F. Merkel und A. Thierfelder (24) (-
Power is draining away from Chancellor Merkel
No full textAngela Merkel managed to secure a fourth term in the 2017 German federal election, but she has faced increasing domestic pressure over recent months. John Ryan writes that the fourth term did not end well for previous German Chancellors Konrad Adenauer and Helmut Kohl, and history appears to be repeating itself for Merkel
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Origin and regenerative potential of vertebrate mechanoreceptor-associated stem cells
No full textWidera D, Hauser S, Kaltschmidt C, Kaltschmidt B. Origin and regenerative potential of vertebrate mechanoreceptor-associated stem cells. Anatomy Research International. 2012;2012:1-9.Meissner corpuscles and Merkel cell neurite complexes are highly specialized mechanoreceptors present in the hairy and glabrous skin, as well as in different types of mucosa. Several reports suggest that after injury, such as after nerve crush, freeze injury, or dissection of the nerve, they are able to regenerate, particularly including reinnervation and repopulation of the mechanoreceptors by Schwann cells. However, little is known about mammalian cells responsible for these regenerative processes. Here we review cellular origin of this plasticity in the light of newly described adult neural crest-derived stem cell populations. We also discuss further potential multipotent stem cell populations with the ability to regenerate disrupted innervation and to functionally recover the mechanoreceptors. These capabilities are discussed as in context to cellularly reprogrammed Schwann cells and tissue resident adult mesenchymal stem cells
Expression of developmentally regulated transcription factors in merkel cell carcinoma
No full textWe have examined a number of developmentally regulated transcription factors for expression in Merkel cells and MCC cell lines and demonstrated that their expression patterns may be prognostic in MCC. We have shown that human Merkel cells from adult scalp hair follicle and from neonatal foreskin epidermal sheets express Brn-3c and HATH1. In addition, results demonstrate that the novel Merkel binding activity complex MNF contains Brn-3c. Moreover, Classic lines which retain neuroendocrine phenotype, are slow growing in culture, grow in suspension and are thought to be less aggressive, retain Brn-2, Brn-3c and HATH1 expression, whereas Variant suspension lines which no longer express NE markers retain Brn-2 and Brn-3c expression, but lack HATH1. Further, Type IV Variant lines which grow as adherent monolayers have shorter doubling times, are more radiation- resistant and have higher cloning efficiencies in soft agar, all thought to be indicative of aggressive tumours, have reduced or no Brn-2 proteins and lack expression of Brn-3c and HATH1 transcription factors.No Full Tex
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