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1.
Am J Psychoanal ; 81(2): 164-177, 2021 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-33953318

RESUMEN

Beginning with Freud, throughout his work and in most if not all psychoanalytic formulations, the concept of trauma has been associated with the disruptive effects of excess excitation on psychic regulatory processes and psychic development. Foremost among these are the capacities for emotional containment and representation. The restoration, strengthening or acquisition for the first time of these capacities can take place intersubjectively in a successful analytic therapy and lies at the heart of the therapeutic action.


Asunto(s)
Psicoanálisis , Terapia Psicoanalítica , Emociones , Humanos , Interpretación Psicoanalítica , Teoría Psicoanalítica
2.
Int J Mol Sci ; 21(18)2020 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-32942630

RESUMEN

Microgravity is known to affect the organization of the cytoskeleton, cell and nuclear morphology and to elicit differential expression of genes associated with the cytoskeleton, focal adhesions and the extracellular matrix. Although the nucleus is mechanically connected to the cytoskeleton through the Linker of Nucleoskeleton and Cytoskeleton (LINC) complex, the role of this group of proteins in these responses to microgravity has yet to be defined. In our study, we used a simulated microgravity device, a 3-D clinostat (Gravite), to investigate whether the LINC complex mediates cellular responses to the simulated microgravity environment. We show that nuclear shape and differential gene expression are both responsive to simulated microgravity in a LINC-dependent manner and that this response changes with the duration of exposure to simulated microgravity. These LINC-dependent genes likely represent elements normally regulated by the mechanical forces imposed by gravity on Earth.


Asunto(s)
Núcleo Celular/fisiología , Citoesqueleto/fisiología , Expresión Génica/fisiología , Matriz Nuclear/fisiología , Línea Celular , Matriz Extracelular/fisiología , Adhesiones Focales/fisiología , Humanos , Ingravidez , Simulación de Ingravidez/métodos
3.
Int J Mol Sci ; 20(10)2019 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-31096581

RESUMEN

The FLUMIAS (Fluorescence-Microscopic Analyses System for Life-Cell-Imaging in Space) confocal laser spinning disk fluorescence microscope represents a new imaging capability for live cell imaging experiments on suborbital ballistic rocket missions. During the second pioneer mission of this microscope system on the TEXUS-54 suborbital rocket flight, we developed and performed a live imaging experiment with primary human macrophages. We simultaneously imaged four different cellular structures (nucleus, cytoplasm, lysosomes, actin cytoskeleton) by using four different live cell dyes (Nuclear Violet, Calcein, LysoBrite, SiR-actin) and laser wavelengths (405, 488, 561, and 642 nm), and investigated the cellular morphology in microgravity (10-4 to 10-5 g) over a period of about six minutes compared to 1 g controls. For live imaging of the cytoskeleton during spaceflight, we combined confocal laser microscopy with the SiR-actin probe, a fluorogenic silicon-rhodamine (SiR) conjugated jasplakinolide probe that binds to F-actin and displays minimal toxicity. We determined changes in 3D cell volume and surface, nuclear volume and in the actin cytoskeleton, which responded rapidly to the microgravity environment with a significant reduction of SiR-actin fluorescence after 4-19 s microgravity, and adapted subsequently until 126-151 s microgravity. We conclude that microgravity induces geometric cellular changes and rapid response and adaptation of the potential gravity-transducing cytoskeleton in primary human macrophages.


Asunto(s)
Citoesqueleto/metabolismo , Macrófagos/citología , Macrófagos/metabolismo , Ingravidez , Citoesqueleto de Actina , Actinas/metabolismo , Línea Celular , Núcleo Celular , Citoplasma , Humanos , Lisosomas , Microscopía Confocal/instrumentación , Microscopía Confocal/métodos , Microscopía Fluorescente/instrumentación , Microscopía Fluorescente/métodos , Monocitos/citología , Vuelo Espacial
4.
Bull Math Biol ; 76(7): 1455-521, 2014 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-24878869

RESUMEN

Systematic evolution of ligands by exponential enrichment (SELEX) is a procedure for identifying nucleic acid (NA) molecules with affinities for specific target species, such as proteins, peptides, or small organic molecules. Here, we extend the work in Seo et al. (Bull Math Biol 72:1623-1665, 2010) (multiple-target SELEX or positive SELEX) and examine an alternate SELEX process with multiple targets by incorporating negative selection into a positive SELEX protocol. The alternate SELEX process is done iteratively by alternating several positive selection rounds with several negative selection rounds. At the end of each positive selection round, NAs are eluted from the bound product and amplified by polymerase chain reaction (PCR) to increase the size of the pool of NA species that bind preferentially to the given positive target vector. The enriched population of NAs is then exposed to the negative targets (undesired targets). The free NA species (instead of the bound NA species being eluted) are retained and amplified by PCR (negative selection). The goal is to minimize an enrichment of nonspecifically binding NAs against multiple targets. While positive selection alone results in a pool of NAs that bind tightly to a given target vector, negative selection results in the subset of the NAs that bind best to the nontarget vectors that are also present. By alternating the two processes, we eventually obtain a refined population of nucleic acids that bind to the desired target(s) with high "selectivity" and "specificity." In the present paper, we give formulations of the negative and alternate selection processes and define their efficiencies in a meaningful way. We study the asymptotic behavior of alternate SELEX system as a discrete-time dynamical system. To do this, we use the chemical potential to examine how alternate SELEX leads to the selection of NAs with more specific interactions when the ratio of the number of positive selection rounds to the number of negative selection rounds is fixed. Alternate SELEX is said to be globally asymptotically stable if, given the initial target vector and a fixed ratio, the distribution of the limiting NA fractions does not depend on the relative concentrations of the NAs in the initial pool (provided that all of the NA species are initially present in the initial pool). We state conditions on the matrix of NA-target affinities that determine when the alternate SELEX process is globally asymptotically stable in this sense and illustrate these results computationally.


Asunto(s)
Aptámeros de Nucleótidos/química , Modelos Teóricos , Ácidos Nucleicos/química , Técnica SELEX de Producción de Aptámeros/métodos , Simulación por Computador , Ligandos , Termodinámica
5.
Int J Psychoanal ; 105(2): 234-241, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38655644

RESUMEN

This paper attempts to expand José Bleger's classic, metapsychological descriptions of the psychoanalytic frame to formulate and emphasize the role of the analyst's internal frame in establishing a psychoanalytic observational perspective in the analytic situation. The rationale for doing so follows from clinical necessity, especially when working with patients and psychic organizations that are 'beyond neurosis' and in non-traditional settings such as distance and telemetric analyses. Clinically speaking, in its most effective state, the analyst's internal frame can inform the possibility of an observational vertex aimed at the intuitive grasp of psychic reality rather than a sense-based, empirical observation of parameters denoted by the elements of a consensually validatable social reality.


Asunto(s)
Teoría Psicoanalítica , Terapia Psicoanalítica , Humanos , Terapia Psicoanalítica/métodos , Psicoanálisis/historia
6.
Am J Bot ; 100(1): 226-34, 2013 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-23281389

RESUMEN

The relationship between fundamental plant biology and space biology was especially synergistic in the era of the Space Shuttle. While all terrestrial organisms are influenced by gravity, the impact of gravity as a tropic stimulus in plants has been a topic of formal study for more than a century. And while plants were parts of early space biology payloads, it was not until the advent of the Space Shuttle that the science of plant space biology enjoyed expansion that truly enabled controlled, fundamental experiments that removed gravity from the equation. The Space Shuttle presented a science platform that provided regular science flights with dedicated plant growth hardware and crew trained in inflight plant manipulations. Part of the impetus for plant biology experiments in space was the realization that plants could be important parts of bioregenerative life support on long missions, recycling water, air, and nutrients for the human crew. However, a large part of the impetus was that the Space Shuttle enabled fundamental plant science essentially in a microgravity environment. Experiments during the Space Shuttle era produced key science insights on biological adaptation to spaceflight and especially plant growth and tropisms. In this review, we present an overview of plant science in the Space Shuttle era with an emphasis on experiments dealing with fundamental plant growth in microgravity. This review discusses general conclusions from the study of plant spaceflight biology enabled by the Space Shuttle by providing historical context and reviews of select experiments that exemplify plant space biology science.


Asunto(s)
Biología , Plantas/metabolismo , Vuelo Espacial
7.
Nat Genet ; 31(2): 216-20, 2002 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-12032569

RESUMEN

In mammals, epigenetic marks on the X chromosomes are involved in dosage compensation. Specifically, they are required for X chromosome inactivation (XCI), the random transcriptional silencing of one of the two X chromosomes in female cells during late blastocyst development. During natural reproduction, both X chromosomes are active in the female zygote. In somatic-cell cloning, however, the cloned embryos receive one active (Xa) and one inactive (Xi) X chromosome from the donor cells. Patterns of XCIhave been reported normal in cloned mice, but have yet to be investigated in other species. We examined allele-specific expression of the X-linked monoamine oxidase type A (MAOA) gene and the expression of nine additional X-linked genes in nine cloned XX calves. We found aberrant expression patterns in nine of ten X-linked genes and hypomethylation of Xist in organs of deceased clones. Analysis of MAOA expression in bovine placentae from natural reproduction revealed imprinted XCI with preferential inactivation of the paternal X chromosome. In contrast, we found random XCI in placentae of the deceased clones but completely skewed XCI in that of live clones. Thus, incomplete nuclear reprogramming may generate abnormal epigenetic marks on the X chromosomes of cloned cattle, affecting both random and imprinted XCI.


Asunto(s)
Clonación de Organismos , Compensación de Dosificación (Genética) , Cromosoma X/genética , Animales , Bovinos , Metilación de ADN , Femenino , Datos de Secuencia Molecular , Monoaminooxidasa/genética , ARN Largo no Codificante , ARN no Traducido/genética , Factores de Transcripción/genética
8.
Psychoanal Q ; 92(4): 641-664, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-38095860

RESUMEN

When we are confronted with the challenge of trying to fully convey or describe something about human life and emotional experience, we find ourselves up against the very limitations of language. This problem becomes especially relevant as we attempt to expand psychoanalytic theory so as to enable us to "approach a mental life unmapped by the theories elaborated for the understanding of neurosis" (Bion1962, p. 37). This paper seeks to aid in that expansion by revisiting Bion's early writings about the beta screen, extending his conclusions about communication from the psychotic part of the mind to the broad area of the unrepresented (the unstructured unconscious), suggesting that there is often a potentially communicative meaning, a mute plea for intersubjective regulatory assistance (alpha function), embedded in the unconscious evocation of emotions in the object and that this cry for help may be encrypted in even the most seemingly destructive, resistant and oppositional patients.


Asunto(s)
Trastornos Mentales , Terapia Psicoanalítica , Humanos , Sueños/psicología , Teoría Psicoanalítica , Emociones
9.
Psychoanal Q ; 92(1): 11-25, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37098259

RESUMEN

The terms unrepresented and unrepresented states are increasingly being referred to in psychoanalytic discourse, without our having established a generally agreed upon consensus about their definition, use or meaning. While these particular designations were never used by Freud, a careful reading of his work reveals them to be qualities that characterize the initial state of both the drive and perception. This paper attempts to place these terms in a clinically useful, metapsychological perspective by reviewing their conceptual origin in Freud and examining their elaboration and clinical relevance in the work of Bion, Winnicott, and Green. These concepts should prove especially useful for understanding and addressing problems presented by non-neurotic patients and psychic organizations and will help expand the reach and efficacy of psychoanalytic understanding and technique to increasing numbers of contemporary patients.


Asunto(s)
Alcadienos , Psicoanálisis , Humanos , Psicoanálisis/historia , Relevancia Clínica , Consenso , Exactitud de los Datos , Teoría Psicoanalítica
10.
Int J Psychoanal ; 104(6): 1054-1062, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-38127475

RESUMEN

Freud's publication of The Ego and the Id sparked a diverging set of psychoanalytic models - ego psychology, structural conflict theory, Kleinianism, object relations theories, Lacanianism, etc. - each of which attempted to deal with the clinical limitations of his first topography in regard to unconscious guilt, negative therapeutic reactions and primitive character organizations. This paper attempts to look back on these developments from the perspective of contemporary, post-Freudian psychoanalytic theories.


Asunto(s)
Ego , Terapia Psicoanalítica , Humanos , Teoría Freudiana , Teoría Psicoanalítica , Apego a Objetos
11.
Ear Nose Throat J ; 102(8): NP400-NP407, 2023 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-33975441

RESUMEN

BACKGROUND: Puncture and lavage of the paranasal sinuses, previously the primary treatment for unresponsive acute bacterial rhinosinusitis before surgery, has been abandoned due to procedural discomfort and advancements in antibiotic efficacy and endoscopic surgery. The rise in antibiotic-resistant bacteria has renewed the interest in minimally invasive sinus lavage to both avoid aggressive surgical interventions and identify appropriate antibiotic therapy. In this article, we describe the safety and feasibility of a new device in human patients and evaluate its efficacy as a treatment before the traditional sinus surgery in acute rhinosinusitis. METHODS: The device with its seeker-shaped guiding tube and rotating wire can enter the sinus cavity through the natural ostium, pulverize the inspissated mucus, and enable lavage and culture sampling without the need for sinus puncturing. It was tested in 6 patients with chronic sinusitis under general anesthesia during endoscopic sinus surgery and in additional 10 patients with maxillary acute bacterial rhinosinusitis in outpatient settings under local anesthesia. RESULTS: The device enabled rapid, efficient, and atraumatic insertion of the wire into the occluded sinuses. The rotating wire permitted pulverization of the thick mucus, which enabled irrigation without mucosal damage or adverse events. Overall, 9 of 10 patients with acute bacterial rhinosinusitis demonstrated remarkable improvements and were discharged the following day with no acute symptoms. The visual analog scale score for pain dropped from 8.9 to 0.4. The remaining one patient underwent endoscopic sinus surgery subsequently. None of the patients treated during endoscopic sinus surgery developed any adverse events.


Asunto(s)
Senos Paranasales , Rinitis , Sinusitis , Humanos , Irrigación Terapéutica , Proyectos Piloto , Rinitis/cirugía , Rinitis/etiología , Senos Paranasales/cirugía , Sinusitis/cirugía , Sinusitis/etiología , Endoscopía/efectos adversos , Antibacterianos , Enfermedad Crónica
12.
Life (Basel) ; 13(3)2023 Feb 23.
Artículo en Inglés | MEDLINE | ID: mdl-36983782

RESUMEN

Plants have been recognized as key components of bioregenerative life support systems for space exploration, and many experiments have been carried out to evaluate their adaptability to spaceflight. Unfortunately, few of these experiments have involved monocot plants, which constitute most of the crops used on Earth as sources of food, feed, and fiber. To better understand the ability of monocot plants to adapt to spaceflight, we germinated and grew Brachypodium distachyon seedlings of the Bd21, Bd21-3, and Gaz8 accessions in a customized growth unit on the International Space Station, along with 1-g ground controls. At the end of a 4-day growth period, seedling organ's growth and morphologies were quantified, and root and shoot transcriptomic profiles were investigated using RNA-seq. The roots of all three accessions grew more slowly and displayed longer root hairs under microgravity conditions relative to ground control. On the other hand, the shoots of Bd21-3 and Gaz-8 grew at similar rates between conditions, whereas those of Bd21 grew more slowly under microgravity. The three Brachypodium accessions displayed dramatically different transcriptomic responses to microgravity relative to ground controls, with the largest numbers of differentially expressed genes (DEGs) found in Gaz8 (4527), followed by Bd21 (1353) and Bd21-3 (570). Only 47 and six DEGs were shared between accessions for shoots and roots, respectively, including DEGs encoding wall-associated proteins and photosynthesis-related DEGs. Furthermore, DEGs associated with the "Oxidative Stress Response" GO group were up-regulated in the shoots and down-regulated in the roots of Bd21 and Gaz8, indicating that Brachypodium roots and shoots deploy distinct biological strategies to adapt to the microgravity environment. A comparative analysis of the Brachypodium oxidative-stress response DEGs with the Arabidopsis ROS wheel suggests a connection between retrograde signaling, light response, and decreased expression of photosynthesis-related genes in microgravity-exposed shoots. In Gaz8, DEGs were also found to preferentially associate with the "Plant Hormonal Signaling" and "MAP Kinase Signaling" KEGG pathways. Overall, these data indicate that Brachypodium distachyon seedlings exposed to the microgravity environment of ISS display accession- and organ-specific responses that involve oxidative stress response, wall remodeling, photosynthesis inhibition, expression regulation, ribosome biogenesis, and post-translational modifications. The general characteristics of these responses are similar to those displayed by microgravity-exposed Arabidopsis thaliana seedlings. However, organ- and accession-specific components of the response dramatically differ both within and between species. These results suggest a need to directly evaluate candidate-crop responses to microgravity to better understand their specific adaptability to this novel environment and develop cultivation strategies allowing them to strive during spaceflight.

13.
Front Plant Sci ; 14: 1284529, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-38162303

RESUMEN

Outside the protection of Earth's magnetic field, organisms are constantly exposed to space radiation consisting of energetic protons and other heavier charged particles. With the goal of crewed Mars exploration, the production of fresh food during long duration space missions is critical for meeting astronauts' nutritional and psychological needs. However, the biological effects of space radiation on plants have not been sufficiently investigated and characterized. To that end, 10-day-old Arabidopsis seedlings were exposed to simulated Galactic Cosmic Rays (GCR) and assessed for transcriptomic changes. The simulated GCR irradiation was carried out in the NASA Space Radiation Laboratory (NSRL) at Brookhaven National Lab (BNL). The exposures were conducted acutely for two dose points at 40 cGy or 80 cGy, with sequential delivery of proton, helium, oxygen, silicon, and iron ions. Control and irradiated seedlings were then harvested and preserved in RNAlater at 3 hrs post irradiation. Total RNA was isolated for transcriptomic analyses using RNAseq. The data revealed that the transcriptomic responses were dose-dependent, with significant upregulation of DNA repair pathways and downregulation of glucosinolate biosynthetic pathways. Glucosinolates are important for plant pathogen defense and for the taste of a plant, which are both relevant to growing plants for spaceflight. These findings fill in knowledge gaps of how plants respond to radiation in beyond-Earth environments.

14.
Life (Basel) ; 12(2)2022 Jan 19.
Artículo en Inglés | MEDLINE | ID: mdl-35207432

RESUMEN

One of the major concerns for long-term exploration missions beyond the Earth's magnetosphere is consequences from exposures to solar particle event (SPE) protons and galactic cosmic rays (GCR). For long-term crewed Lunar and Mars explorations, the production of fresh food in space will provide both nutritional supplements and psychological benefits to the astronauts. However, the effects of space radiation on plants and plant propagules have not been sufficiently investigated and characterized. In this study, we evaluated the effect of two different compositions of charged particles-simulated GCR, and simulated SPE protons on dry and hydrated seeds of the model plant Arabidopsis thaliana and the crop plant Mizuna mustard [Brassica rapa var. japonica]. Exposures to charged particles, simulated GCRs (up to 80 cGy) or SPEs (up to 200 cGy), were performed either acutely or at a low dose rate using the NASA Space Radiation Laboratory (NSRL) facility at Brookhaven National Lab (BNL). Control and irradiated seeds were planted in a solid phytogel and grown in a controlled environment. Five to seven days after planting, morphological parameters were measured to evaluate radiation-induced damage in the seedlings. After exposure to single types of charged particles, as well as to simulated GCR, the hydrated Arabidopsis seeds showed dose- and quality-dependent responses, with heavier ions causing more severe defects. Seeds exposed to simulated GCR (dry seeds) and SPE (hydrated seeds) had significant, although much less damage than seeds exposed to heavier and higher linear energy transfer (LET) particles. In general, the extent of damage depends on the seed type.

15.
Methods Mol Biol ; 2368: 281-299, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-34647262

RESUMEN

Since opportunities to conduct experiments in space are scarce, various microgravity simulators and analogs have been widely used in space biology ground studies. Even though microgravity simulators do not produce all of the biological effects observed in the true microgravity environment, they provide alternative test platforms that are effective, affordable, and readily available to facilitate microgravity research. The Microgravity Simulation Support Facility (MSSF) at the National Aeronautics and Space Administration (NASA) John F. Kennedy Space Center (KSC) has been established for conducting short duration experiments, typically less than 1 month, utilizing a variety of microgravity simulation devices for research at different gravity levels. The simulators include, but are not limited to, 2D Clinostats, 3D Clinostats, Random Positioning Machines, and Rotating Wall Vessels. In this chapter, we will discuss current MSSF capabilities, development concepts, and the physical characteristics of these microgravity simulators.


Asunto(s)
Vuelo Espacial , Simulación de Ingravidez , Ingravidez , Estados Unidos , United States National Aeronautics and Space Administration
16.
Int J Psychoanal ; 102(4): 794-807, 2021 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-34357847

RESUMEN

The concept of Trauma in psychoanalysis has suffered from overuse and inconsistent use. A review of Freud's writings beginning with the Project indicates that from the perspective of the impact upon psychic processes, Freud held a more consistent view of the concept that, if recognized, can help avoid the often fruitless etiological debates of internal vs. external cause, intrinsic (drive) vs. extrinsic (reality) factors, etc. What is more helpful from a clinical perspective, is to view the various challenges that a given set of potentially trauma-inducing circumstances might pose for an individual, consider each individual's highly subjective mode of experiencing and responding to those challenges and take into account the supports offered in any instance by the specific familial, social or cultural surround. Each set of experiences that will be qualified as 'trauma' that any of us undergoes will to some extent be understood and integrated into our particular subjectivities according to our unique, subjective organizations of self, understandings of and position in the world.


Asunto(s)
Psicoanálisis , Teoría Freudiana , Humanos
17.
Bull Math Biol ; 72(7): 1623-65, 2010 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-20077028

RESUMEN

SELEX (Systematic Evolution of Ligands by Exponential Enrichment) is a procedure by which a mixture of nucleic acids can be fractionated with the goal of identifying those with specific biochemical activities. One combines the mixture with a specific target molecule and then separates the target-NA complex from the resulting reactions. The target-NA complex is separated from the unbound NA by mechanical means (such as by filtration), the NA is eluted from the complex, amplified by PCR (polymerase chain reaction), and the process repeated. After several rounds, one should be left with the nucleic acids that best bind to the target. The problem was first formulated mathematically in Irvine et al. (J. Mol. Biol. 222:739-761, 1991). In Levine and Nilsen-Hamilton (Comput. Biol. Chem. 31:11-25, 2007), a mathematical analysis of the process was given. In Vant-Hull et al. (J. Mol. Biol. 278:579-597, 1998), multiple target SELEX was considered. It was assumed that each target has a single nucleic acid binding site that permits occupation by no more than one nucleic acid. Here, we revisit Vant-Hull et al. (J. Mol. Biol. 278:579-597, 1998) using the same assumptions. The iteration scheme is shown to be convergent and a simplified algorithm is given. Our interest here is in the behavior of the multiple target SELEX process as a discrete "time" dynamical system. Our goal is to characterize the limiting states and their dependence on the initial distribution of nucleic acid and target fraction components. (In multiple target SELEX, we vary the target component fractions, but not their concentrations, as fixed and the initial pool of nucleic acids as a variable starting condition). Given N nucleic acids and a target consisting of M subtarget component species, there is an M × N matrix of affinities, the (i,j) entry corresponding to the affinity of the jth nucleic acid for the ith subtarget. We give a structure condition on this matrix that is equivalent to the following statement: For any initial pool of nucleic acids such that all N species are represented, the dynamical system defined by the multiple target SELEX process will converge to a unique subset of nucleic acids, each of whose concentrations depend only upon the total nucleic acid concentration, the initial fractional target distribution (both of which are assumed to be the same from round to round), and the overall limiting association constant. (The overall association constant is the equilibrium constant for the system of MN reactions when viewed as a composite single reaction). This condition is equivalent to the statement that every member of a certain family of chemical potentials at infinite target dilution can have at most one critical point. (The condition replaces the statement for single target SELEX that the dynamical system generated via the process always converges to a pool that contains only the nucleic acid that binds best to the target). This suggests that the effectiveness of multiple target SELEX as a separation procedure may not be as useful as single target SELEX unless the thermodynamic properties of these chemical potentials are well understood.


Asunto(s)
Algoritmos , Aptámeros de Nucleótidos/química , Ácidos Nucleicos/química , Técnica SELEX de Producción de Aptámeros/métodos
18.
J Math Biol ; 60(1): 1-26, 2010 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-19274464

RESUMEN

Many biologically important macromolecular reactions are assembled and catalyzed at the cell lipid-surface and thus, the extracellular matrix and the glycocalyx layer mediate transfer and exchange of reactants and products between the flowing blood and the catalytic lipid-surface. This paper presents a mathematical model of reaction-diffusion equations that simply describes the transfer process and explores its influence on surface reactivity for a prototypical pathway, the tissue factor (Tf) pathway of blood coagulation. The progressively increasing friction offered by the matrix and glycocalyx to reactants and to the product (coagulation factors X, VIIa and Xa) approaching the reactive surface is simulated and tested by solving the equations numerically with both, monotonically decreasing and constant diffusion profiles. Numerical results show that compared to isotropic transfer media, the anisotropic structure of the matrix and glycocalyx sharply decreases overall reaction rates and significantly increases the mean transit time of reactants; this implies that the anisotropy modifies the distribution of reactants. Results also show that the diffusional transfer, whether isotropic or anisotropic, influences reaction rates according to the order at which the reactants arrive at the boundary. Faster rates are observed when at least one of the reactants is homogeneously distributed before the other arrives at the boundary than when both reactants transfer simultaneously from the boundary.


Asunto(s)
Matriz Extracelular/metabolismo , Glicocálix/metabolismo , Modelos Biológicos , Animales , Difusión , Enzimas/metabolismo , Humanos , Cinética , Conceptos Matemáticos
19.
Int J Psychoanal ; 101(6): 1162-1171, 2020 12.
Artículo en Inglés | MEDLINE | ID: mdl-33952115

RESUMEN

The Repetition Compulsion has been the source of much controversy and perplexity. From it's clinical introduction in 1914 in Remembering, Repeating and Working Through to it's metapsychological elaboration in 1920 in Beyond the Pleasure Principle, it has occupied a central position in Freud's thinking. Especially in regard to his later work, it can be seen to be intrinsic to his final dual instinct theory, his theories of the Death Instinct, trauma, memory, binding and action and to the clinical challenges and theoretical changes that led to the formulation of his second topography. This paper will trace the evolution of the concept in Freud and in certain post-Freudian authors, especially Edward Bibring, Winnicott and Scarfone.


Asunto(s)
Conducta Compulsiva/psicología , Teoría Freudiana/historia , Historia del Siglo XX , Humanos , Instinto , Memoria , Placer , Teoría Psicoanalítica
20.
J Am Psychoanal Assoc ; 68(1): 9-25, 2020 02.
Artículo en Inglés | MEDLINE | ID: mdl-32183570

RESUMEN

Psychoanalysis has seen a shift in emphasis regarding therapeutic action and technique. A predominant focus on the uncovering or reintegrating of repressed, disguised, or split-off contents has moved to include the intersubjective creation, development, and strengthening of psychic processes and capabilities. The analyst's role in this process has been analogized to that of the primary maternal object in the origins of psychic life. This metaphor illuminates the movement from unrepresented to represented psychic states in treatment, as seen in a clinical example from the analysis of a particularly withdrawn young adult.


Asunto(s)
Parapsicología , Terapia Psicoanalítica/métodos , Adaptación Psicológica , Humanos , Relaciones Metafisicas Mente-Cuerpo , Apego a Objetos , Interpretación Psicoanalítica , Teoría Psicoanalítica , Represión Psicológica
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