4,527 research outputs found
Charles M. Breder, Jr.: Palmetto Key, 1942
Charles M. Breder and his wife Ethel spent part of the summer of 1942 at the Palmetto Key field station, known today as Cabbage Key, on the west coast of Florida south of
Charlotte Harbor. The Palmetto Key field station began in 1938 and ended in 1942 because of World War II. His Palmetto Key diary ran for 95 pages of notes, tables,
diagrams, drawings, lists, and business records and this report presents a variety of fascinating entries. Diaries from other years all bear Breder's style of discipline,
curiosity, humor, and speculations on nature. The diary was transcribed as part of the Coastal Estuarine Data/Document Rescue and Archeology effort for South Florida. (PDF contaons 24 pages
Identification of Store-independent and Store-operated Ca2+ Conductances in Caenorhabditis elegans Intestinal Epithelial Cells
The nematode Caenorhabditis elegans offers significant experimental advantages for defining the genetic basis of diverse biological processes. Genetic and physiological analyses have demonstrated that inositol-1,4,5-trisphosphate (IP3)–dependent Ca2+ oscillations in intestinal epithelial cells play a central role in regulating the nematode defecation cycle, an ultradian rhythm with a periodicity of 45–50 s. Patch clamp studies combined with behavioral assays and forward and reverse genetic screening would provide a powerful approach for defining the molecular details of oscillatory Ca2+ signaling. However, electrophysiological characterization of the intestinal epithelium has not been possible because of its relative inaccessibility. We developed primary intestinal epithelial cell cultures that circumvent this problem. Intestinal cells express two highly Ca2+-selective, voltage-independent conductances. One conductance, IORCa, is constitutively active, exhibits strong outward rectification, is 60–70-fold more selective for Ca2+ than Na+, is inhibited by intracellular Mg2+ with a K1/2 of 692 μM, and is insensitive to Ca2+ store depletion. Inhibition of IORCa with high intracellular Mg2+ concentrations revealed the presence of a small amplitude conductance that was activated by passive depletion of intracellular Ca2+ stores. Active depletion of Ca2+ stores with IP3 or ionomycin increased the rate of current activation ∼8- and ∼22-fold compared with passive store depletion. The store-operated conductance, ISOC, exhibits strong inward rectification, and the channel is highly selective for Ca2+ over monovalent cations with a divalent cation selectivity sequence of Ca2+ > Ba2+ ≈ Sr2+. Reversal potentials for ISOC could not be detected accurately between 0 and +80 mV, suggesting that PCa/PNa of the channel may exceed 1,000:1. Lanthanum, SKF 96365, and 2-APB inhibit both IORCa and ISOC reversibly. Our studies provide the first detailed electrophysiological characterization of voltage-independent Ca2+ conductances in C. elegans and form the foundation for ongoing genetic and molecular studies aimed at identifying the genes that encode the intestinal cell channels, for defining mechanisms of channel regulation and for defining their roles in oscillatory Ca2+ signaling
Oscillatory Ca2+ Signaling in the Isolated Caenorhabditis elegans Intestine: Role of the Inositol-1,4,5-trisphosphate Receptor and Phospholipases C β and γ
Defecation in the nematode Caenorhabditis elegans is a readily observable ultradian behavioral rhythm that occurs once every 45–50 s and is mediated in part by posterior body wall muscle contraction (pBoc). pBoc is not regulated by neural input but instead is likely controlled by rhythmic Ca2+ oscillations in the intestinal epithelium. We developed an isolated nematode intestine preparation that allows combined physiological, genetic, and molecular characterization of oscillatory Ca2+ signaling. Isolated intestines loaded with fluo-4 AM exhibit spontaneous rhythmic Ca2+ oscillations with a period of ∼50 s. Oscillations were only detected in the apical cell pole of the intestinal epithelium and occur as a posterior-to-anterior moving intercellular Ca2+ wave. Loss-of-function mutations in the inositol-1,4,5-trisphosphate (IP3) receptor ITR-1 reduce pBoc and Ca2+ oscillation frequency and intercellular Ca2+ wave velocity. In contrast, gain-of-function mutations in the IP3 binding and regulatory domains of ITR-1 have no effect on pBoc or Ca2+ oscillation frequency but dramatically increase the speed of the intercellular Ca2+ wave. Systemic RNA interference (RNAi) screening of the six C. elegans phospholipase C (PLC)–encoding genes demonstrated that pBoc and Ca2+ oscillations require the combined function of PLC-γ and PLC-β homologues. Disruption of PLC-γ and PLC-β activity by mutation or RNAi induced arrhythmia in pBoc and intestinal Ca2+ oscillations. The function of the two enzymes is additive. Epistasis analysis suggests that PLC-γ functions primarily to generate IP3 that controls ITR-1 activity. In contrast, IP3 generated by PLC-β appears to play little or no direct role in ITR-1 regulation. PLC-β may function instead to control PIP2 levels and/or G protein signaling events. Our findings provide new insights into intestinal cell Ca2+ signaling mechanisms and establish C. elegans as a powerful model system for defining the gene networks and molecular mechanisms that underlie the generation and regulation of Ca2+ oscillations and intercellular Ca2+ waves in nonexcitable cells
Computer Simulation of the Elastic Properties of Titanium Alloys for Medical Applications
© 2016, Springer Science+Business Media New York.Results of a computer simulation of the elastic properties of α+β- and β-titanium alloys, used for medical purposes, within the framework of the molecular-dynamics method are presented. It is shown that β-titanium alloys are best suited for the use as bone implants because of their small moduli of elasticity. The advisability of the use of the molecular-dynamics method for the study of the elastic properties of titanium alloys, serving as bone implants, is demonstrated
New variable separation approach: application to nonlinear diffusion equations
The concept of the derivative-dependent functional separable solution, as a
generalization to the functional separable solution, is proposed. As an
application, it is used to discuss the generalized nonlinear diffusion
equations based on the generalized conditional symmetry approach. As a
consequence, a complete list of canonical forms for such equations which admit
the derivative-dependent functional separable solutions is obtained and some
exact solutions to the resulting equations are described.Comment: 19 pages, 2 fig
Psychological Intervention for Development of Disease Awareness in Addicts: Villa Colibri Therapeutic Community of Santiago De Cuba
In the research, a Mixed Method was used and the execution was through a sequential exploratory design. For the initial diagnosis was used, semi-structured interview, sentence completion test, disease awareness questionnaire, attitude to the disease, interpersonal relationships, and conflict management, were the dimensions of the awareness indicator of the disease. Based on the results of the diagnosis, the Psychological Intervention Program was developed, based on the cognitive-behavioral model with a humanistic approach. with respect to the attitude towards the disease, the subjects predominated in ambivalence in 70.6% and non-consciousness in 23.5%, referring to interpersonal relationships, ambivalent in 58.8% and not healthy in 29.4% and conflict management was inconsistent in 70.6%, and inadequate in 23.5%, after the development of the program, positive attitude increased 52.9% and ambivalence decreased to 41.2%, healthy interpersonal relationships grew to 47.1% and adequate conflict management was imposed in 58.8% of the sample. The lack of awareness of the disease in patients was identified, the preliminary results of the application of the program proved to be very useful to develop awareness of the disease in the subjects studied, thus achieving a better therapeutic adherence
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