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1.
In the past decade, translational control has been shown to be crucial in the regulation of gene expression. Research in this field has progressed rapidly, revealing new control mechanisms and adding constantly to the list of translationally regulated genes. There is accumulating evidence that translational control plays a primary role in cell-cycle progression and cell differentiation, as well as in the induction of specific cellular functions. Recently, the aetiologies of several human diseases have been linked with mutations in genes of the translational control machinery, highlighting the significance of this regulatory mechanism. In addition, deregulation of translation is associated with a wide range of cancers. Current research focuses on novel therapeutic strategies that target translational control, a promising concept in the treatment of human diseases.  相似文献   

2.
A body plan is a suite of characters shared by a group of phylogenetically related animals at some point during their development. The concept of bauplane, or body plans, has played and continues to play a central role in the study of evolutionary developmental biology (evo-devo). Despite the importance of the body plan concept in evo-devo, many researchers may not be familiar with the progression of ideas that have led to our current understanding of body plans, and/or current research on the origin and maintenance of body plans. This lack of familiarity, as well as former ties between the body plan concept and metaphysical ideology is likely responsible for our underappreciation of the body plan concept in its own right, as well as its role in evo-devo. My aim in this review is to outline how we have arrived at our modern definition of body plan, the controversies associated with the concept, its role in evo-devo, and how current research is informing us on body plans. To this end, I integrate concepts such as the nature of phyla, the Cambrian explosion, constraint, evolvability, and results from recent research on gene regulatory networks with the much older concept of the body plan.  相似文献   

3.
Anthony Wrigley 《Bioethics》2015,29(7):478-487
The concept of vulnerability has been subject to numerous different interpretations but accounts are still beset with significant problems as to their adequacy, such as their contentious application or the lack of genuine explanatory role for the concept. The constant failure to provide a compelling conceptual analysis and satisfactory definition leaves the concept open to an eliminativist move whereby we can question whether we need the concept at all. I highlight problems with various kinds of approach and explain why a satisfactory account of vulnerability is unlikely ever to be offered if we wish the concept to play a genuinely explanatory role in bioethical contexts. I outline why an eliminativist position should be taken with regard to this concept in light of these concerns but mitigate some of the severity of this position by arguing that we can still make sense of retaining our widespread use of the term by viewing it as nothing more than a useful pragmatic linguistic device that acts as a marker to draw attention to certain kinds of issue. These issues will be entirely governed by other, better understood ethical concepts and theories.  相似文献   

4.
Pedro Barbosa 《Oecologia》1977,29(4):311-327
Summary The investigations of the bionomics and parasitoid-host interactions of some gypsy moth parasitoids provide an opportunity to consider the role of r and K strategies in the life history of some tachinid and hymenopterous parasitoid species. Available historic data as well as results of recent studies are utilized in an attempt to evaluate the degree to which the data conform to this paradigm. Few studies have provided the information required to evaluate this concept particularly in a parasitoid complex. The concept of r and K also is discussed in relation to biological control strategies, and the implications of this analysis for those arguments are discussed.This paper, No. 2059 (Massachusetts Agricultural Experiment Station) is made possible from research supported (in part) from Experiment Station Project No. 355  相似文献   

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"哮喘控制"是指可在患者中观察到的,通过治疗减少或消除的哮喘症状程度。支气管哮喘全球倡议指南(GINA)通过肺功能、气道高反应性和控制评价量表等工具来评价患者哮喘控制程度。其中,哮喘控制评价量表在疾病评估中占有重要地位。本文基于哮喘控制概念发展的四个阶段,梳理不同阶段国内外哮喘控制评价量表,总结量表临床应用研究的主要结论,对未来制定更全面、更符合临床的哮喘控制量表提出建议。  相似文献   

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TCV-116, a recently developed angiotensin II (Ang II) receptor antagonist, was administered orally (1 mg/kg per day) to 10-week-old spontaneously hypertensive rats (SHR) for 2 weeks. Blood pressure and plasma components of the renin-angiotensin-aldosterone system were determined in these rats. TCV-116 produced a marked reduction in blood pressure without altering heart rate. Whereas plasma renin concentration (PRC), angiotensin I (Ang I) and angiotensin II (Ang II) all were significantly increased, plasma aldosterone was decreased by approximately 70% compared with control animals. These results not only indicate therapeutic efficacy of this agent in the chronic treatment of human hypertension, but support also the concept that the renin-angiotensin system plays an important role in the control of blood pressure in this animal model of human essential hypertension.  相似文献   

9.
Postural reflexes are replaced soon after birth by automatic reactions that allow for volition and cognition. It is still an enigma how this change in postural control is achieved. We suggest that the change involves the formation of a sensory processing level (meta level) that becomes interleaved in between the tight sensor-actuator coupling of the classic reflexes. We assume that the brain applies at this level intersensory interactions to reconstruct the physical stimuli which are causing the physiological stimuli and sensory signals. The thus derived estimates of the physical stimuli are then used as feedback signals in the posture control system. We present this concept on the background of the classic reflex concept and earlier attempts in the literature to overcome it. The earlier attempts were often motivated by the question how the brain prevents voluntary movements from being hampered by reflexive stabilisation of posture (so-called posture-movement problem). We compare our new concept with the classic reflex concept in a theoretical approach, by implementing both concepts into simple postural control models. In simulations of the two models we superimpose external perturbations (the physical stimuli) and a voluntary body lean movement. We show that it is possible to achieve successful stimulus compensation and unperturbed lean movement with both, the model derived from the new concept and the one of the classic reflex concept. With both approaches, the posture-movement problem does not arise. Based on preliminary considerations that include experimental findings from the literature, however, we conclude that the new concept provides more explanatory power than the classic reflex concept.  相似文献   

10.
Gamaleĭ IuV 《Ontogenez》2005,36(3):165-181
Phylogenetic and ontogenetic relationships between the plastids, cell endoplasmic reticulum, and plant transport communication have been reviewed. The initiating role of plastids (endosymbionts) in the origin of endoplasmic reticulum (buffer zone of endosymbiogenesis) has been shown, as well as a similar role of endoplasmic reticulum in the development of transport communication of xylem and phloem. Plastids, sugars and transport system for their distribution can be interpreted as leading sections in the mechanism of developmental control: gene expression of nuclear genome and genome of organelles, cell and tissue differentiation, and plant morphogenesis. The conflict between the bulk of plant genome and low percentage of its realization is explained as a result of limitation of the nuclear genome realization by plastid genome. The concept of development as applied to plant ontogenesis has been critically analyzed. The possibilities of the concept correction by with the help of symbiogenetic hypothesis are discussed.  相似文献   

11.
In home network environments, OSGi platform plays a major role as the service gateway to access into home appliances. It is important to provide appropriate services as well as security mechanisms to protect confidential or sensitive information and devices. Authorization is especially important when controlling the access of different users. OSGi platform supports the role based access control but it does not support various facilities in the RBAC model. To address such shortcomings, several works have proposed the enhanced access control mechanisms for the OSGi service platform. However, these are still limited to applying the traditional RBAC conventions to OSGi platform. This paper extends the existing authorization mechanism of OSGi platform to address its limitations for dynamic deployments. By adding the relative role concept and activating the access control using the delegation model, proposed mechanism enables a diverse and outstanding access control. We implement the proposed mechanism using aspectJ and illustrate how to develop a bundle including access control logic.  相似文献   

12.
Leptin plays a central role in weight control by suppressing food intake and increasing energy expenditure. The concept of leptin resistance emerged to explain the seemingly paradoxical elevated leptin levels in obesity. Recent discoveries reveal that protein tyrosine phosphatases are key players in leptin resistance by globally suppressing leptin signaling.  相似文献   

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An activated sludge aeration control concept was developed utilizing off-gas nitrous oxide concentrations as a surrogate for autotrophic nitrifying bacterial inhibition and aeration air as a master control variable. The control concept was evaluated using a simulated pilot scale bioreactor (mathematically calibrated liquid phase process model and a model to link off-gas nitrous oxide generation to liquid phase conditions) as a data generator. When applied to the simulated system, the process controller was successful at maintaining the process at the desired operating setpoint and promoting stable operation by minimizing periods of significant inhibition. Furthermore, it provided a more efficient use of the air supplied to the bioreactor during periods of varying feed loading by matching the air supply to the metabolic demands, substantially reducing periods of over and under-aeration. The findings of this research demonstrate the potential for off-gas nitrous oxide monitoring as a completely non-invasive alternative to liquid phase monitoring used in conventional dissolved oxygen control. Investigations are currently underway at the laboratory scale to evaluate the benefits and limitations associated with this control concept, with particular emphasis on implementation issues and the quantification of potential aeration and cost savings.  相似文献   

15.
How do plant growth substances work?   总被引:17,自引:10,他引:7  
Abstract. Despite intensive research effort, the role of growth substances in the life of the intact growing plant is far from clear. Two reasons are suggested which may account for the lack of progress. The first is the failure to recognize the unique aspects of plant development. These which are expressed by the regenerative, organizational and developmental plasticity of the meristem probably result from the possession of growth substances. The second is the concept of growth substances as hormones. This represents the main conceptual thrust of research and is considered critically, starting with the historical system, the coleoptile and dealing with other major growth substance systems in turn. It is concluded that a hormonal concept which includes control by changes in growth substance concentration fails to explain the developmental phenomena under examination. A role for growth substances as integrating agents is suggested and the notion of quantitative tissue sensitivity variation is developed to explain the major growth patterns of developing shoots.  相似文献   

16.
The concept on social and ecologic determination of the epidemic process in its direct connection with L.V. Gromashevsky's doctrine on the transmission mechanism of the causative agents of infection is presented. The role of this concept in the development of epidemiological science is discussed.  相似文献   

17.
The present paper analyzes the use and understanding of the homology concept across different biological disciplines. It is argued that in its history, the homology concept underwent a sort of adaptive radiation. Once it migrated from comparative anatomy into new biological fields, the homology concept changed in accordance with the theoretical aims and interests of these disciplines. The paper gives a case study of the theoretical role that homology plays in comparative and evolutionary biology, in molecular biology, and in evolutionary developmental biology. It is shown that the concept or variant of homology preferred by a particular biological field is used to bring about items of biological knowledge that are characteristic for this field. A particular branch of biology uses its homology concept to pursue its specific theoretical goals.  相似文献   

18.
Summary The accumulation and proliferation of vascular smooth muscle cells (VSMC) within the vessel wall is an important pathogenic feature in the development of atherosclerosis. Glucose metabolism has been implicated to play an important role in this cellular mechanism. To further elucidate the role of glucose metabolism in atherogenesis, glycolysis and its regulation have been investigated in proliferating VSMC. Platelet derived growth factor (PDGF BB)-induced proliferation of VSMCs significantly stimulated glucose flux through glycolysis. Further evaluating the enzymatic regulation of this pathway, the analysis of flux:metabolite co-responses revealed that anaerobic glycolytic flux is controlled at different sites of gycolysis in proliferating VSMCs, being consistent with the concept of multisite modulation. These findings indicate that regulation of glycolytic flux in proliferating VSMCs differs from traditional concepts of metabolic control of the Embden–Meyerhof pathway.  相似文献   

19.
Allergic bronchial asthma (BA) is characterized by chronic airway inflammation, development of airway hyperreactivity and recurrent reversible airway obstruction. T-helper 2 cells and their products have been shown to play an important role in this process. In contrast, the mechanisms by which immune cells interact with the cells residing in lung and airways, such as neurons, epithelial or smooth muscle cells, still remains uncertain. Sensory and motor neurons innervating the lung exhibit a great degree of functional plasticity in BA defined as 'neuronal plasticity'. These neurons control development of airway hyperresponsiveness and acute inflammatory responses, resulting in the concept of 'neurogenic inflammation'. Such quantitative and/or qualitative changes in neuronal functions are mediated to a great extent by a family of cytokines, the neurotrophins, which in turn are produced by activated immune cells, among others in BA. We have therefore developed the concept that neurotrophins such as nerve growth factor and brain-derived neurotrophic factor link pathogenic events in BA to dysfunctions of the immune and nervous system.  相似文献   

20.
Summary. Diabetes mellitus is a primary contributor to progressive kidney dysfunction leading to end-stage renal disease (ESRD). In the early phase of diabetes, prior to the onset of further complications, both kidney size and glomerular filtration rate (GFR) increase. Glomerular hyperfiltration is considered a risk factor for downstream complications and progression to ESRD. Abnormalities in vascular control have been purported to account for the glomerular hyperfiltration in early diabetes. In this review we discuss a tubulo-centric concept in which tubular growth and subsequent hyper-reabsorption contribute to the onset of glomerular hyperfiltration that demarks the early stage of diabetes. Kidney growth, in this concept, is no longer relegated to a compensatory response to hyperfiltration, but rather plays a primary and active role in its genesis and progression. As such, components of kidney growth, such as the polyamines, may provide a means of early detection of diabetic kidney dysfunction and more effective therapeutic intervention.  相似文献   

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