Individual neurons display characteristic firing patterns determined by the number and kind of ion channels in their membranes. We describe experimental and computational studies that suggest that neurons use activity sensors to regulate the number and kind of ion channels and receptors in their membrane to maintain a stable pattern of activity and to compensate for ongoing processes of degradation, synthesis and insertion of ion channels and receptors. We show that similar neuronal and network outputs can be produced by a (...) number of different combinations of ion channels and synapse strengths. This suggests that individual neurons of the same class may each have found an acceptable solution to a genetically determined pattern of activity, and that networks of neurons in different animals may produce similar output patterns by somewhat variable underlying mechanisms. BioEssays 24:1145–1154, 2002. © 2002 Wiley Periodicals, Inc. (shrink)

Antonio Damasio elabora una teoría de la mente humana y de la conducta moral a partir de su hipótesis sobre la evolución de los mecanismos de autorregulación biológicos. En ella, a la capacidad para representar relaciones organismo-mundo se le confiere un importante papel en los cambios organizacionales que emergen de los sistemas con un sistema nervioso central. Concretamente, en nuestro artículo analizamos, en primer lugar, la tesis acerca de la doble homeostasis biológica- mental que caracteriza a los agentes racionales. (...) Desde su perspectiva, la conciencia es producto y manifestación de complejos procesos del procesamiento de representaciones, los cuales favorecen la regulación no consciente. Además, para entender los procesos conscientes también es clave, según Damasio, conocer cómo la evolución de tales mecanismos está asociada con el desarrollo de áreas neuronales próximas al córtex emocional, especialmente, el giro cingulado. Los argumentos que Damasio utiliza para vincular los procesos representacionales con la particular preocupación humana por los sentimientos de los otros es la segunda cuestión que evaluamos. (shrink)

Since it was inspired by Bernard and developed and named by Cannon, the conceptof homeostasis has been invoked by many as the central theoretical framework for physiology. Ithas also been the target of numerous criticisms that have elicited the introduction of a plethoraof alternative concepts. We argue that many of the criticisms actually target the more restrictiveaccount of homeostasis advanced by the cyberneticists. What was crucial to Bernard and Cannonwas a focus on the maintenance of the organism as (...) the goal of physiological regulation. We analysehow Bernard’s and Cannon’s broad conception of what was required to maintain the organismwas narrowed to negative feedback, characterized in terms of setpoints, by the cyberneticistsand demonstrate how many of the alternative concepts challenge the role of setpoints – treatingthem as variable in light of circumstances or in anticipation of future circumstances, or asdispensable altogether. To support our analysis, we draw on the experimental and theoreticalwork on thermoregulation, a phenomenon that has been considered as a paradigmatic example ofhomeostasis and has been a common focus of those advancing alternative concepts. To integratethe insights advanced by the original proponents of homeostasis and the theorists proposingreplacement notions we advance a framework in which regulation is viewed from the perspectiveof maintaining the organism. (shrink)

Hunger is a psychological state that serves physiological energy homeostasis. I argue that it is a pure underived desire to eat and examine its role in homeostasis. After scene-setting explanations of homeostasis and desire, I argue that hunger is a close phenomenological match with underived desire. Then, I show why desire is an apt instrument for energy homeostasis. Finally, I argue that energy homeostasis is a multi-factorial future-regarding behavioural strategy. Hunger is a special purpose sensory (...) state that serves only to implement the strategy. Thus, it is a sensory desire. I conclude by reflecting on the credibility of this desire. (shrink)

Christopher Boorse’s Biostatistical Theory of Health has been the main contender among naturalistic accounts of health for the last 40 years. Yet, a recent criticism of this theory, presented by Elselijn Kingma, identifies a dilemma resulting from the BST’s conceptual linking of health and statistical typicality. Kingma argues that the BST either cannot accommodate the situation- specificity of many normal functions or cannot account for many situation-specific diseases. In this article, we expand upon with Daniel Hausman’s response to Kingma’s dilemma. (...) We propose that recalling Boorse’s specification that health is an intrinsic property of its bearers and explicating this intrinsic property in relation to the concept of homeostasis can illuminate how proponents of naturalistic accounts of health should deal with the situation- specificity of normal functions. We argue that beyond what Boorse and Hausman have delineated, the situation- specificity of normal function cannot be fully captured in a simple dichotomy between normal and abnormal environment or between relevant and irrelevant situations. By bringing homeostasis to the fore of the analysis of health, we set out a richer picture of what the various situations that affect living organisms’ functional performance can be. Accordingly, we provide a broader classification of these various situations which, we contend, better accounts for the main intuitions that philosophers of medicine have sought to accommodate than previous naturalistic theories of health. (shrink)

Several authors have argued that higher taxa are monophyletic homeostatic property cluster natural kinds. On the traditional definition of monophyly, this will not work: the emergence of taxon-defining homeostatic property clusters would not always correspond to unique speciation events. An alternative conception of monophyly is developed and advocated, which can accommodate the homeostatic property cluster proposal. Recent work in philosophy of science shows that it meets appropriate standards of objectivity and precision.

Yan Xin Life Science Technology-Optimized Caloric Restriction (YXLST-CR) is a unique food abstinence, which suppresses appetite and sensation of hunger while maintaining physiological homeostasis. The authors review the first clinical case study on YXLST-CR, or YXLST-bigu, a 15-day, 24-hour observation in 1987 on a 21-year-old female undergoing YXLST-bigu for several months. The participant took no food or water and conducted normal physical activities. The daily records of body weight, temperature, pulse rate, blood pressure, and daily urine test results showed (...) no abnormalities. Homeostasis was maintained during YXLST-CR. The authors also report serum leptin levels in a group of individuals undergoing YXLST-CR and a control group before and after a 24-hour water-only period. The leptin level prior to the observation for the YXLST-CR group was lower than that for the control group and remained unchanged during the observation, suggesting the possibilities of an established metabolic adaptation. (shrink)

The formal properties of orbits in a plane are explored by elementary topology. The notions developed from first principles include: convex and polygonal orbits; convexity; orientation, winding number and interior; convex and star-shaped regions. It is shown that an orbit that is convex with respect to each of its interior points bounds a convex region. Also, an orbit that is convex with respect to a fixed point bounds a star-shaped region.Biological considerations that directed interest to these patterns are indicated, and (...) the implications of the prospect of higher orders of star-shapedness mentioned. (shrink)

We propose that sleep is linked to synaptic homeostasis. Specifically, we propose that: (1) Wakefulness is associated with synaptic potentiation in cortical circuits; (2) synaptic potentiation is tied to the homeostatic regulation of slow wave activity; (3) slow wave activity is associated with synaptic downscaling; and (4) synaptic downscaling is tied to several beneficial effects of sleep, including performance enhancement.

Adult stem cell populations must coordinate their own maintenance with the generation of differentiated cell types to sustain organ physiology, in a spatially controlled manner and over long periods. Quantitative analyses of clonal dynamics have revealed that, in epithelia, homeostasis is achieved at the population rather than at the single stem cell level, suggesting that feedback mechanisms coordinate stem cell maintenance and progeny generation. In the central nervous system, however, little is known of the possible community processes underlying neural (...) stem cell maintenance. Recent work, in part based on intravital imaging made possible in the adult zebrafish, conclusively highlights that homeostasis in neural stem cell pools may rely on population asymmetry and long‐term spatiotemporal coordination of neural stem cell states and fates. These results suggest that neural stem cell assemblies in the vertebrate brain behave as self‐organized systems, such that the stem cells themselves generate their own intrinsic niche. (shrink)

"Exhalation," a 2008 science fiction short story by Ted Chiang, virtuoso of the genre and the form, begins with a truism, refuted: "It has long been said that air (which others call argon) is the source of life. This is not in fact the case, and I engrave these words to describe how I came to understand the true source of life and, as a corollary, the means by which life will one day end" (37). The narrator's promise is so (...) alluring—knowledge of life's origin, knowledge of its expiration, and knowledge of the relation between the two—that we may be forgiven for overlooking the parenthetical. Argon amounts to less than one percent of the air breathed within Earth's atmosphere. The narrator specifies that "others call... Read More. (shrink)

The human intestines are constantly under the influence of numerous pathological factors: enteropathogenic microorganisms, food antigens, physico‐chemical stress associated with digestion and bacterial metabolism, therefore it must be provided with a system of protection against adverse impact. Recent studies have shown that Paneth cells play a crucial role in maintaining homeostasis of the small intestines. Paneth cells perform many vital functions aimed at maintaining a homeostatic balance between normal microbiota, infectious pathogens and the human body, regulate the qualitative composition (...) and number of intestinal microorganisms, prevent the introduction of potentially pathogenic species, and protect stem cells from damage. Paneth cells take part in adaptive and protective‐inflammatory reactions. Paneth cells maintain dynamic balance between microbial populations, and the macroorganism, preventing the development of intestinal infections and cancer. They play a crucial role in gastrointestinal homeostasis and may be key factors in the etiopathological progression of intestinal diseases. (shrink)

The idea that a human being may select at will outcomes of certain quantum events, and that this is free will, has been put forward long ago. But how can such a possibility to control quantum randomness be recombined with the necessity to obey the known statistical distributions of the laws of nature? Antoine Suarez proposes a Quantum Homeostasis Hypothesis (QHH), where this may happen during sleep or dreams. Divine providence may also be placed exactly here without violating the (...) free will of a human being, and in accordance with the necessity to follow the statistical laws of nature. God may instruct one during sleep and dreams. Apart from the Bible, this is attested to by sources in many ancient civilizations. This essay addresses this aspect of QHH in an attempt to answer the question whether data may show that our “acts of will” during dreams differ from such during a fully conscious state of mind. (shrink)

Maintaining intestinal homeostasis is a key prerequisite for a healthy gut. Recent evidence points out that microRNAs (miRNAs) act at the epicenter of the signaling networks regulating this process. The fine balance in the interaction between gut microbiota, intestinal epithelial cells, and the host immune system is achieved by constant transmission of signals and their precise regulation. Gut microbes extensively communicate with the host immune system and modulate host gene expression. On the other hand, sensing of gut microbiota by (...) the immune cells provides appropriate tolerant responses that facilitate the symbiotic relationships. While the role of many regulatory proteins, receptors and their signaling pathways in the regulation of the intestinal homeostasis is well documented, the involvement of non‐coding RNA molecules in this process has just emerged. This review discusses the most recent knowledge about the contribution of miRNAs in the regulation of the intestinal homeostasis. (shrink)

Principal propositions -- Synergetic and homeostatic transformations of energies in the natural space -- Mathematical basis for the applicability of synergy and homeostasis in the normative systems -- Natural normative order and comparison of the aggression of nonhuman and human animals -- Applicability of synergy and homeostasis for the normative transformations in civil society -- Applicability of synergy and homeostasis for the normative transformations in legal order -- Human rights and applicability of synergy and homeostasis for (...) the normative transformations in state -- The theory on the prevention of environmental disaster. (shrink)

Ubiquitin is the most phylogenetically conserved protein known. This 8,500 Da polypeptide can be covalently attached to cellular proteins as a posttranslational modification. In most cases, the addition of multiple ubiquitin adducts to a protein targets it for rapid degradation by a multisubunit protease known as the 26S proteasome. While the ubiquitin/26S proteasome pathway is responsible for the degradation of the bulk of cellular proteins during homeostasis, it may also be responsible for the rapid loss of protein during the (...) programmed death of certain cells, such as skeletal muscle during insect metamorphosis. In addition, alterations in the expression and regulation of ubiquitin may play significant roles in pathological disorders. For example, dramatic increases in ubiquitin and ubiquitin‐protein conjugates are observed in a wide variety of neurodegenerative disorders, including Alzheimer's disease. Patients suffering from the autoimmune disease systemic lupus erythematosus generate antibodies reacting with ubiquitin and ubiquitinated histones. At present, it is not known whether these changes in ubiquitin expression and regulation initiate pathological changes in these diseases or if they are altered as a consequence of these disorders. (shrink)

While purely causal theories of reference have provided a plausible account of the meanings of names and natural kind terms, they cannot handle vacuous theoretical terms. The causal homeostasis theory can but incurs other difficulties. Theories of reference that are intensional and not purely causal tend to be molecularist or holist. Holist theories threaten transtheoretic reference, whereas molecularist theories must supply a principled basis for selecting privileged meaning-determining relations between terms. The causal homeostasis theory is a two-factor molecularist (...) theory, but it fails to provide such a principled basis and collapses into holism. A naturalistic, non-foundationalist holism that deploys strategies of intertheoretic reduction and co-evolutionary pluralism can, however, yield a credible version of transtheoretic reference. (shrink)

Long non‐coding RNAs (lncRNAs) have recently gained increasing attention because of their crucial roles in gene regulatory processes. Functional studies using mammalian skin as a model system have revealed their role in controlling normal tissue homeostasis as well as the transition to a diseased state. Here, we describe how lncRNAs regulate differentiation to preserve an undifferentiated epidermal progenitor compartment, and to maintain a functional skin permeability barrier. Furthermore, we will reflect on recent work analyzing the impact of lncRNAs on (...) the progression from normal epithelium to the development of skin disorders and cancer. (shrink)

A large body of evidence on the activity of regulatory T (Treg) cells was gathered during the last decade, and a similar number of reviews and opinion papers attempted to integrate the experimental findings. The abundant literature clearly delineates an exciting area of research but also underlines some major controversies. A linear cause–result interpretation of experimental maneuvers often ignores the fact that the activity of Treg cells is orchestrated with the effector T (Teff) cells within an intricate network of physiological (...) immune homeostasis. Every modulation of the activity of the effector (cytotoxic) immune system revolves to affect the activity of regulatory (suppressive) cells through elaborate feedback loops of negative and positive regulation. The lack of IL‐2 production by innate Treg cells makes this cytokine a prime coupler of the effector and suppressive mechanisms. Here we attempt to integrate evidence that delineates the involvement of IL‐2 in primary and secondary feedback loops that regulate the activity of suppressive cells within the elaborate network of physiological immune homeostasis.©2007 Wiley Periodicals, Inc BioEssays 30:875–888, 2008. © 2008 Wiley Periodicals, Inc. (shrink)

의례는 신화와 더불어 종교를 구성하는 중요한 요인이었다. 그러나 근대에 접어들면서 종교의 의미가 약화되었고, 사회의 의례는 전근대적인 것으로 간주되었다. 하지만 의례는 단순히 전통을 고수하는 것이 아니라 변화하는 환경에 적응하는 중요한 능력으로 간주된 다. 이 논문에서는 라파포트(Roy Rappaport)의 항상성 개념에 주목하며 순자(荀子)의 ‘변 화’와 ‘상’의 개념을 분석하고자 한다. ‘항상성’이라는 개념은 본래 살아있는 유기체에서 일어나는 과정을 일컫는 개념이었지만, 인류학자인 라파포트는 그의 인류생태학(human ecology) 이론에서 항상성 개념을 적극적으로 활용한다. 라파포트에 따르면 ‘항상성’은 단 순히 균형을 넘어서 ‘동적으로 안정된 상태’를 말한다. 순자는 성인의 중요한 능력으로 사회 (...) 질서를 유지하고, 자연과 인간이 조화를 이루도록 하여 인류의 생존과 번영에 기여하는 것으로 생각한다. 그러기 위해서 성인은 우선 예측 불가능한 환경 속에 적응할 수 있는 ‘변화(變化)’의 능력을 갖추어야 한다. 또한 성인은 외 부 환경의 교란에도 불구하고 인간 사회에 일정함을 유지할 수도 있어야 하는데, 이것은 순자 에서 ‘상(常)’으로 표현된다. 그리고 ‘상’은 라파포트가 말하는 ‘동적으로 안정된 상 태’로 이해될 여지가 다분히 있다. 이와 같은 연구는 기존에 구습(舊習) 심지어 악습(惡習)으로 간주되었던 의례의 사회적 기능을 되짚어보는 데 의의가 있다. 또한 의례라는 것이 단순히 전통을 지킴으로써 기존의 사회 질서를 유지하는 것이 아니라 자연과 문화의 균형, 자연과 인간의 균형 등에 어떻게 기여하는지를 밝히는 데 도움이 될 것이다. (shrink)

Mitochondrial homeostasis serves as a cornerstone of cellular function, orchestrating a delicate balance between energy production, redox status, and cellular signaling transduction. This equilibrium involves a myriad of interconnected processes, including mitochondrial dynamics, quality control mechanisms, and biogenesis and degradation. Perturbations in mitochondrial homeostasis have been implicated in a wide range of diseases, including neurodegenerative diseases, metabolic syndromes, and aging‐related disorders. In the past decades, the discovery of numerous mitochondrial proteins and signaling has led to a more complete (...) understanding of the intricate mechanisms underlying mitochondrial homeostasis. Recent studies have revealed that Family with sequence similarity 210 member A (FAM210A) is a novel nuclear‐encoded mitochondrial protein involved in multiple aspects of mitochondrial homeostasis, including mitochondrial quality control, dynamics, cristae remodeling, metabolism, and proteostasis. Here, we review the function and physiological role of FAM210A in cellular and organismal health. This review discusses how FAM210A acts as a regulator on mitochondrial inner membrane to coordinate mitochondrial dynamics and metabolism. (shrink)

Origin of life on earth transpired once and from then on, it emerges as an endless eternal process. Matter and energy are constants of the cosmos and the hypothesis is that the origin of life is a moment when these constants intertwined or interacted. Energy from the cosmos interacted with inorganic matter to support matter with retention of this riveted energy, as energy to be circulated within the primitive channelized structures to conserve energy by the materialization of the proton (...) class='Hi'>homeostasis mechanisms developed from the obtainable inorganic matter. The driver for these processes as we now confirm, exists in the quantum world and through quantum phenomenal processes could have combined these constants to create the magic of life. Primitive earth was a chemical reactive system that triggered a macromolecular evolution by means of open thermodynamic systems, driven by cyclic gradients of temperature, electromagnetic radiation and chemical potentials which sustained life and proto-consciousness in the first life forms driven by the quantum processes. The origin of life is always an intriguing topic but the purpose for finding the cause should never be inclined towards obliterating it; for if that is the case, the further we seek, the farther it will go. (shrink)

Iron delivered by transferrin to the interior of the cell is in part utilized in biosynthetic processes and in part incorporated into ferritin, the major iron storage protein. The intracellular ferritin concentration is directly correlated to and determined by the extent of iron supply to the cell. Intracellular partitioning of iron to ferritin is suggested as forming the basis of cellular iron homeostasis.