12,147 research outputs found
Quantifying the roles of cell motility and cell proliferation in a circular barrier assay
No full textMoving fronts of cells are essential features of embryonic development, wound repair and cancer metastasis. This paper describes a set of experiments to investigate the roles of random motility and proliferation in driving the spread of an initially confined cell population. The experiments include an analysis of cell spreading when proliferation was inhibited. Our data have been analysed using two mathematical models: a lattice-based discrete model and a related continuum partial differential equation model. We obtain independent estimates of the random motility parameter, D, and the intrinsic proliferation rate, λ, and we confirm that these estimates lead to accurate modelling predictions of the position of the leading edge of the moving front as well as the evolution of the cell density profiles. Previous work suggests that systems with a high λ/D ratio will be characterized by steep fronts, whereas systems with a low λ/D ratio will lead to shallow diffuse fronts and this is confirmed in the present study. Our results provide evidence that continuum models, based on the Fisher–Kolmogorov equation, are a reliable platform upon which we can interpret and predict such experimental observations.Matthew J. Simpson, Katrina K. Treloar, Benjamin J. Binder, Parvathi Haridas, Kerry J. Manton, David I. Leavesley, D. L. Sean McElwain and Ruth E. Bake
Evolution of cooperation among tumor cells
No full textThe evolution of cooperation has a well established theoretical framework based on game theory. This approach has made valuable contributions to a wide variety of disciplines, including political science, economics, and evolutionary biology. Existing cancer theory suggests that individual clones of cancer cells evolve independently from one another, acquiring all of the genetic traits or hallmarks necessary to form a malignant tumor. It is also now recognized that tumors are heterotypic, with cancer cells interacting with normal stromal cells within the issue microenvironment, including endothelial, stromal, and nerve cells. This tumor cell???stromal cell interaction in itself is a form of commensalism, because it has been demonstrated that these nonmalignant cells support and even enable tumor growth. Here, we add to this theory by regarding tumor cells as game players whose interactions help to determine their Darwinian fitness. We marshal evidence that tumor cells overcome certain host defenses by means of diffusible products. Our original contribution is to raise the possibility that two nearby cells can protect each other from a set of host defenses that neither could survive alone. Cooperation can evolve as byproduct mutualism among genetically diverse tumor cells. Our hypothesis supplements, but does not supplant, the traditional view of carcinogenesis in which one clonal population of cells develops all of the necessary genetic traits independently to form a tumor. Cooperation through the sharing of diffusible products raises new questions about tumorigenesis and has implications for understanding observed phenomena, designing new experiments, and developing new therapeutic approaches.Author manuscript. Published in final edited form as: Proc Natl Acad Sci U S A. 2006 September 5; 103(36): 13474-13479.The final published version of this article is located at: www.pnas.org/cgi/doi/10.1073/pnas.0606053103NIH U56 CA113004; to David E. AxelrodR.A. was supported by National Science Foundation (NSF) Grant SES-0240852. D.E.A. was supported by NSF Grant IIS-0312953, National Institutes of Health (NIH) Grant U56 CA113004, and New Jersey Commission on Cancer Research Grant 1076-CCR-SO. K.J.P. is an American Cancer Society Clinical Research Professor and is supported by NIH Grants CA69568, CA102872, and CA093900.NIH CA69568; to Kenneth J. PientaNIH CA102872; to Kenneth J. PientaNIH CA093900; to Kenneth J. PientaNSF SES-0240852; to Robert AxelrodNJ Commission on Cancer Research 1076-CCR-SO; to David E. AxelrodAlso available in PubMed Central. PMCID: PMC155738
The Arts Interview. Dr. David Pitt : The Truant Years, E. J. Pratt
No full textHost Fred Hollingshurst interviews Dr. David Pitt of Memorial University, who discusses the life and work of Newfoundland poet E. J. Pratt. Pitt is the author of E. J. Pratt: The Truant Years, 1881-1927
Epidemiology of Erosive Tooth Wear, Dental Fluorosis and Molar Incisor Hypomineralization in the American Continent
Full text linkNon-carious dental lesions such as developmental defects of enamel (DDE) and erosive tooth wear (ETW) are the subject of intensive research. This paper aims to give perspectives on both DDE, including dental fluorosis and molar incisor hypomineralization (MIH), and ETW, presenting epidemiological data from the Americas and associated diagnostic aspects. Besides, it is important to present evidence to guide the clinical assessment process, supporting the clinicians' management decisions towards better oral health of their patients. The overall increase in the worldwide prevalence of non-carious lesions discussed in this this paper may reflect the need of perceptual changes. Although the number of publications related to these conditions has been increasing in the last years, there is still a need for clinical diagnostic and management awareness to include these conditions in routine dental practice. Besides, it is important to provide recommendations for standardized clinical assessment criteria, improving the process and helping clinicians' adherence. In this sense, this paper discusses the most commonly implemented indices for each condition. Thus, despite the wide range of diagnostic indices, BEWE is proposed to be the index recommended for ETW assessment, Dean or Thylstrup & Fejerskov indices for fluorosis and preferably the EAPD criteria (or modified DDE index) for MIH. Overall, non-carious lesions are a growing concern, and it is important to implement preventive measures that control their severity and progression, and accurate diagnosis by the dental clinician
Non-alcoholic steatohepatitis in children and adolescents
No full textCopyright © 2000 Australasian Medical PublishingWe describe 17 children with non-alcoholic steatohepatitis. All had elevated levels of serum liver enzymes and 16 were morbidly obese. Liver biopsy showed variable steatosis and fibrosis in nine patients. At follow-up, 12 of 14 patients had persistent morbid obesity and 11 had elevated liver enzyme levels.Nicholas D Manton, Jill Lipsett, David J Moore, Geoffrey P Davidson, Anthony J Bourne and Richard T L Coupe
Detection and diagnosis of carious lesions:Factual clinical approaches
Full text linkMinimal intervention dentistry is the accepted contemporary approach for caries management -both for the disease and the lesion. The development of adjunctive technologies to assist early lesion detection and quantifcation has led to the marketing of various devices over the past two decades. A thorough understanding of the clinical relevance of these devices is important to make precise interpretation of the information provided by the individual technologies. In this chapter, we will describe and discuss the most common commercially available carious lesion detection technologies in order to give dental practitioners clear information about the technology details and reliable and reproducible use of each device, its advantages and limitations, using a clinical approach.</p
Fly about round me coursing, swallow sweet birds come near [first line]
No full textstrophicpiano and voiceCover is duplicated in 125.115b.Johns Hopkins University, Levy Sheet Music Collection, Box
125, Item 115aTranslated From the French of Volney L'Hotelier by Samuel J. Gardner, Esq. The Music by Felicien David (Author of "Le Desert").E.G. Warren, Engr
Fly about round me coursing, swallow sweet birds come near [first line]
No full textstrophicpiano and voiceCover is duplicated in 125.115b.Johns Hopkins University, Levy Sheet Music Collection, Box
125, Item 115aTranslated From the French of Volney L'Hotelier by Samuel J. Gardner, Esq. The Music by Felicien David (Author of "Le Desert").E.G. Warren, Engr
A SEM and non-contact surface white light profilometryin vivostudy of the effect of a crème containing CPP-ACP and fluoride on young etched enamel
No full textThe aim of this in vivo study was to evaluate the short and a longer term effect on enamel of the application of a crème containing 10% CPP-ACP and 900ppm fluoride, in orthodontically planned, high caries-risk patients. Epoxy resin replicas of upper lateral incisors were obtained from polyvinyl siloxane (PVS) impressions, before and after etching. The right incisors were left untreated in order to control saliva remineralizing potential. The upper left surfaces were coated with a pea-size amount of the crème. Replicas were obtained at 3 weeks and 6 months and analyzed by SEM and non-contact surface white light profilometry. In the treated sample the profilometric roughness parameters at 3 weeks were statistically significantly lower than the control group values (p<0.05). At 3 weeks SEM images of the enamel surface showed fewer irregularities. After 6 months, differences between test and control groups were not present on SEM images and profilometric values. CPP-ACP and fluoride crème had positive in vivo effects on enamel surfaces. Significant differences in surface roughness existed after a 3-week period of crème use
Interview with David Dunn on the subject of bark beetle sounds
No full textAnimaliaArthropodaInsectaColeopteraCompressed from .wav format into .mp3 delivery formatComposer and recording engineer David Dunn describes his recordings of bark beetles in New Mexico, and some of the possible causes and consequences of bark beetle infestations devastating pine forests throughout the WestSounds were recorded using a modified transducer inserted into the bark of the tree, and are taken with permission of the author from the compact disc "The Sound of Light in Trees" produced by David Dunn in collaboration with the Acoustic Ecology Institute. Scientists say that bark beetle populations are increasing in large part because of increased drought and milder winters due to global warming
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