Результаты поиска

Osmotic homeostasis.

Alterations in water homeostasis can disturb cell size and function. Although most cells can internally regulate cell volume in response to osmolar stress, neurons are particularly at risk given a combination of complex cell function and space restriction within the calvarium. Thus, regulating water balance is fundamental to survival. Through specialized neuronal "osmoreceptors" that sense changes in plasma osmolality, vasopressin release and thirst are titrated in order to achieve water balance. Fine-tuning of water absorption occurs along the collecting duct, and depends on unique structural…

Optimising homeostasis.

There is a wealth of experimental and clinical information showing that hypertension, hyperglycaemia, hyperthermia and intracranial hypertension are each independent indicators of a poor prognosis after stroke, but there is an astonishing lack of evidence from randomised controlled trials to tell us how to manage these problems, bearing in mind their frequency in stroke patients. The therapeutic options will, in most cases, not involve patented drugs, and financial support for running the necessary randomised controlled trials will have to come from government or charity sponsors rather than f

Epithelial homeostasis.

Epithelia form intelligent, dynamic barriers between the external environment and an organism's interior. Intercellular cadherin-based adhesions adapt and respond to mechanical forces and cell density, while tight junctions flexibly control diffusion both within the plasma membrane and between adjacent cells. Epithelial integrity and homeostasis are of central importance to survival, and mechanisms have evolved to ensure these processes are maintained during growth and in response to damage. For instance, cell competition surveys the fitness of cells within epithelia and removes the less fit; …

Potassium homeostasis.

Potassium balance is regulated by appropriate changes in potassium excretion in the distal portion of the nephron. By contrast, potassium intake, absorption and proximal renal reabsorption do not show regulatory variation. Extracellular potassium concentration, which is a critical factor in membrane polarization, may at times vary in a direction opposite to total body content, because of altered distribution across cell membranes. Alterations in acid-base status frequently disturb homeostasis by altering potassium movement into cells, while insulin has an important regulatory effect on distrib…

[Homeostasis and Disorder of Musculoskeletal System.Mechanisms of cartilage development and homeostasis.].

Chondrocytes, which are originated from undifferentiated mesenchymal stem cells, play roles in skeletal development and growth in mammal, an … Prg4 were identified as important molecules associated with articular cartilage development and its homeostasis, the molecular mechanisms are very unclear to date.

Множественный склероз: расстройство перестроенного T-Cell Homeostasis

Существует неопределенность в отношении того, способствуют ли аналогичные или различные механизмы патогенезу различных подтипов множественного склероза (МС). Детальный анализ наивного гомеостазиза клеток Т показывает, что пациенты с повторно излучающими MS (RRMS) и с первичным прогрессивным MS (PPMS) имеют раннее наступление тимической инструкции, что приводит к снижению тимической производительности. Снижение тимической производительности приводит к вторичным периферийным гомеостатическим изменениям в наивных CD4 Т-клеток, которые тесно имитируют изменения Т-клеток, наблюдаемые в эксперимента

Совпадение в аннотации оригинала
Uncertainty exists as to whether similar or different mechanisms contribute to the pathogenesis of different subtypes of multiple sclerosis (MS). Detailed analysis of naive T cell homeostasis shows that patients with relapsing-remitting MS (RRMS) and with primary progressive MS (PPMS) have early-onset thymic involution that causes reduced thymic output. The …

Homeostasis and narcolepsy.

Narcolepsy is characterized by irresistible daytime sleep episodes and cataplectic attacks. Because of the finding of an ultradian rhythmicity of slow-wave sleep in narcolepsy, an alteration of nonrapid eye movement sleep homeostatic regulation has been hypothesized to explain the impairment of the sleep-wakefulness cycle. This hypothesis was tested by two different methods: 1) a sleep-deprivation method (16 or 24 hours) increasing the prior sleep wakefulness and 2) a bed-rest method shortening the prior sleep wakefulness. In both studies normal subjects, sex- and age-matched to narcoleptic su

Transition Metal Homeostasis.

This chapter focuses on transition metals. All transition metal cations are toxic-those that are essential for Escherichia coli and belong to the first transition period of the periodic system of the element and also the "toxic-only" metals with higher atomic numbers. Common themes are visible in the metabolism of these ions. First, there is transport. High-rate but low-affinity uptake systems provide a variety of cations and anions to the cells. Control of the respective systems seems to be mainly through regulation of transport activity (flux control), with control of gene expression playing

Cellular Iron Homeostasis.

Iron is an essential nutrient for all eukaryotic cells, yet it is potentially toxic. Cells have elegant systems coordinating the uptake, use, storage, and export of this metal while also responding to extracellular cues for regulating uptake and efflux. Here we describe the basic systems that operate in all cells with the goal of maintaining iron homeostasis in a highly dynamic system. In mammalian tissues and organs, multiple cell types are highly specialized in their iron management with the goal of maintaining cellular homeostasis subordinate to achieving a more specific function, e.g., die…

Phosphate homeostasis disorders.

Our understanding of the regulation of phosphate balance has benefited tremendously from the molecular identification and characterization of genetic defects leading to a number of rare inherited or acquired disorders affecting phosphate homeostasis. The identification of the key phosphate-regulating hormone, fibroblast growth factor 23 (FGF23), as well as other molecules that control its production, such as the glycosyltransferase GALNT3, the endopeptidase PHEX, and the matrix protein DMP1, and molecules that function as downstream effectors of FGF23 such as the longevity factor Klotho and th…

Brain iron homeostasis.

The anatomical and cellular distribution of non-haem iron, ferritin, transferrin, and the transferrin receptor have been studied in postmortem human brain and these studies, together with data on the uptake and transport of labeled iron, by the rat brain, have been used to elucidate the role of iron and other metal ions in certain neurological disorders. High levels of non-haem iron, mainly in the form of ferritin, are found in the extrapyramidal system, associated predominantly with glial cells. In contrast to non-haem iron, the density of transferrin receptors is highest in cortical and brai

Calcium homeostasis during hibernation and in mechanical environments disrupting calcium homeostasis.

To maintain calcium homeostasis during physical inactivity, precise coordination is necessary between different organs of the body. There are a number of factors which alter an organism's calcium balance, such as growth, aging, physical inactivity and acquired or inherited disorders which ultimately lead to bone loss. In non-hibernating mammals, physical inactivity causes bone loss which may not be completely recoverable during the lifespan of an individual despite a resumption of activity. Extreme physical inactivity and nutritional deprivation are two other important factors that lead to bon…

The biology of water homeostasis.

Water homeostasis is controlled by a brain-kidney axis that consists of central osmoreceptors, synthesis and secretion of arginine vasopressin (AVP) and AVP-responsive aquaporin-2 (AQP2) water channels in kidney collecting duct principal cells that facilitate water reabsorption. In addition to AVP, thirst represents a second line of defence to maintain water balance. Water balance disorders arise because of deficiency, resistance or inappropriate secretion of AVP or disturbances in thirst sensation (hypodipsia, polydipsia). People with water balance disorders are prone to develop hyponatraemia…

Energy homeostasis in the bone.

The bone serves as an energy reservoir and actively engages in whole-body energy metabolism. Numerous studies have determined fuel requirements and bioenergetic properties of bone under physiological conditions as well as the dysregulation of energy metabolism associated with bone metabolic diseases. Here, we review the main sources of energy in bone cells and their regulation, as well as the endocrine role of the bone in systemic energy homeostasis. Moreover, we discuss metabolic changes that occur as a result of osteoporosis. Exploration in this area will contribute to an enhanced comprehens…

Oxygen Sensing and Homeostasis.

OBJECTIVE: The objective of present study was to assess the relationship between the dietary intake and blood status of riboflavin and the prevalence of systemic inflammation among both depressed and nondepressed nurses. METHODS: This was a cross-sectional study on 98 female clinical nurses (45 depressed and 53 nondepressed subjects). Depression status was assessed using the Beck Depression Inventory. We assessed dietary intake of riboflavin using 3-day 24-hour recalls. The serum concentrations of high-sensitive C-reactive protein (hs-CRP) were also measured. Riboflavin status was assessed as

Immunological homeostasis of the eye.

Uveitis is a sight-threatening disease caused by autoimmune or infection-related immune responses. Studies in experimental autoimmune uveitis and in human diseases imply that activated CD4(+) T cells, Th1 and Th17 cells, play an effector role in ocular inflammation. The eye has a unique regional immune system to protect vision-related cells and tissues from these effector T cells. The immunological balance between the pathogenic CD4(+) T cells and regional immune system in the eye contributes to the maintenance of ocular homeostasis and good vision. Current studies have demonstrated that ocula…

Disorders of phosphorus homeostasis.

PURPOSE OF REVIEW: The study of phosphorus physiology and investigations into clinical disorders of phosphorus metabolism has blossomed over the past decade. Recent work has confirmed and further extended our knowledge of basic mechanisms of phosphorus metabolism. RECENT FINDINGS: This review will focus on FGF-23 and Klotho, and on the recent further dissection of their roles in phosphorus and skeletal metabolism. Additionally, this review will detail recent studies that implicate a role for these phosphaturic and vitamin D regulating factors in extraskeletal calcification, including that occ

Calcium homeostasis in pregnancy.

The demands of fetal growth lead to an adaptation of maternal homeostasis in order to provide the required calcium from enhanced intestinal absorption rather than from mobilization of maternal skeletal reserves. In large part this adaptive process depends on the interrelationship between PTH and 1,25(OH)2D which shows quantitative rather than qualitative changes from the non-pregnant state. In contrast the maintenance of fetal mineral homeostasis largely depends on PTHrP which regulates active placental calcium transfer and the calcium fluxes across the kidney and bone. The major source of PTH…