首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
If one looks back on the history of American research ethics, a bold pattern emerges. Since World War II, about every twenty years or so a breach of the social contract between investigators and human research subjects galvanizes public and professional interest in the ethical foundations and oversight mechanisms governing research with humans.  相似文献   

2.
3.
4.
Data on cytological peculiarities of dorsomedial nucleus neurones of the amygdala complex, one of the main zones of sexual dimorphism, in dynamics of estrous cycle are reported. We show that structural and functional characteristics of "dark" and "pale" cells may change depending on the concentrations of gonadal steroids in estrous and metaestrous stages. This specifies the previous hypothesis about mutual reorganization of these cells.  相似文献   

5.
The distribution in the human genome of the largest family of mobile elements, the Alu sequences, has been investigated for the past 30 years, and the vast majority of Alu sequences were shown to have the highest density in GC-rich isochores. Ten years ago, it was discovered, however, that the small "youngest" (most recently transposed) Alu families had a strikingly different distribution compared with the "old" families. This raised the question as to how this change took place in evolution. We solved what was considered to be a "mystery" by 1) revisiting our previous results on the integration and stability of retroviral sequences, and 2) assessing the densities of acceptor sites TTTT/AA in isochore families. We could conclude 1) that the open state of chromatin structure plays a crucial role in allowing not only the initial integration of retroviral sequences but also that of the youngest Alu sequences, and 2) that the distribution of old Alus can be explained as due to Alu sequences being unstable in the GC-poor isochores but stable in the compositionally matching GC-rich isochores, again in line with what happens in the case of retroviral sequences.  相似文献   

6.
7.
8.
9.
Nitration in neurodegeneration: deciphering the "Hows" "nYs"   总被引:3,自引:0,他引:3  
Reynolds MR  Berry RW  Binder LI 《Biochemistry》2007,46(25):7325-7336
Recent literature has ushered in a new awareness of the diverse post-translational events that can influence protein folding and function. Among these modifications, protein nitration is thought to play a critical role in the onset and progression of several neurodegenerative diseases. While previously considered a late-stage epiphenomenon, nitration of protein tyrosine residues appears to be an early event in the lesions of amyotrophic lateral sclerosis, Parkinson's disease, and Alzheimer's disease. The advent of highly specific biochemical and immunological detection methods reveals that nitration occurs in vivo with biological selectively and site specificity. In fact, nitration of only a single Tyr residue is often sufficient to induce profound changes in the activity of catalytic proteins and the three-dimensional conformation of structural proteins. Presumably, nitration modifies protein function by altering the hydrophobicity, hydrogen bonding, and electrostatic properties within the targeted protein. Most importantly, however, nitrative injury may represent a unifying mechanism that explains how genetic and environmental causes of neurological disease manifest a singular phenotype. In this review and synthesis, we first examine the pathways of protein nitration in biological systems and the factors that influence site-directed nitration. Subsequently, we turn our attention to the structural implications of site-specific nitration and how it affects the function of several neurodegeneration-related proteins. These proteins include Mn superoxide dismutase and neurofilament light subunit in amyotrophic lateral sclerosis, alpha-synuclein and tyrosine hydroxylase in Parkinson's disease, and tau in Alzheimer's disease.  相似文献   

10.
In this article, I draw on anthropological and feminist scholarship on the body and the nature/culture divide as a framework for understanding the place of surrogate mothers in a conceptual ideology that connects motherhood with nature. I explore links between the medicalization of childbirth in Israel and the personal agency of surrogate mothers as relayed through interviews. Taking the patriarchal context of the Israeli surrogacy law of 1996 into consideration, I underscore surrogates' imaginative use of medical metaphors as tools for the subversion of surrogacy's threatening social connotations. By redefining the surrogate body as "artificial" and locating "nature" in the commissioning mother's body, surrogates adopt medical rhetoric to transform surrogacy from a transgressive act into an alternative route toward achieving normative Israeli national reproductive goals.  相似文献   

11.
12.
13.
V I Utekhin 《Tsitologiia》1979,21(1):21-24
The ultrastructure of B-cells in the rat pancreatic islets has been studied under various experimental conditions (thyroidectomy, continuous thyroxine treatment, regeneration after partial pancreatectomy, thyroidectomy with partial pancreatectomy, partial pancreatectomy, partial pancreatectomy with continuous thyroxine treatment). Five types of B-cells have been distinguished. It has been supposed that "light" B-cell 1 is related to the stage of secretory granule extrusion, "light" B-cell 2 reflects the extrusion of secretory material and the early stages of secretory granule synthesis; "dark" B-cell 1 is involved in the intensive synthesis, formation and extrusion of secretory material, and "dark" B-cell 2 in the intensive secretory granule synthesis, formation and storage.  相似文献   

14.
Antidepressants pyrazidol (pirlindole), incazan, imipramine, nialamide, nomifensine, mianserin were shown to reduce the duration of immobilization in mice in "despair" tests and increase the number of rotations in water "escape" tests.  相似文献   

15.
Malcolm J.  Coe 《Journal of Zoology》1967,151(1):313-321
Previous references to "necking" behaviour, and the main features of the study area are briefly outlined.
"Necking" behaviour in giraffe takes place only in all male herds. When the animals are in a head to head posture the intensity is either high or low, but when animals take up a head to tail posture the actions are always of high intensity and appear to have greater sexual significance.
The significance of "necking" is discussed, and it is suggested that these ritualized actions form an important sexuo-social bonding mechanism whereby a hierarchy is created amongst the males,and movement between strictly bachelor and mixed herds helps to maintain contact between the sexesin this polygamous mammal.  相似文献   

16.
Rejecting "the given" in systematics   总被引:3,自引:1,他引:2  
How morphology and systematics come together through morphological analysis, homology hypotheses and phylogenetic analysis is a topic of continuing debate. Some contemporary approaches reject biological evaluation of morphological characters and fall back on an atheoretical and putatively objective (but, in fact, phenetic) approach that defers to the test of congruence for homology assessment. We note persistent trends toward an uncritical empiricism (where evidence is believed to be immediately “given” in putatively theory‐free observation) and instrumentalism (where hypotheses of primary homology become mere instruments with little or no empirical foundation for choosing among competing phylogenetic hypotheses). We suggest that this situation is partly a consequence of the fact that the test of congruence and the related concept of total evidence have been inappropriately tied to a Popperian philosophy in modern systematics. Total evidence is a classical principle of inductive inference and does not imply a deductive test of homology. The test of congruence by itself is based philosophically on a coherence theory of truth (coherentism in epistemology), which is unconcerned with empirical foundation. We therefore argue that coherence of character statements (congruence of characters) is a necessary, but not a sufficient, condition to support or refute hypotheses of homology or phylogenetic relationship. There should be at least some causal grounding for homology hypotheses beyond mere congruence. Such causal grounding may be achieved, for example, through empirical investigations of comparative anatomy, developmental biology, functional morphology and secondary structure. © The Willi Hennig Society 2006.  相似文献   

17.
The late Bronze Age wall painting the Boxing Boys (c. 17th-16th century BCE) was excavated in the ancient town of Akrotiri on the Greek island of Thera. This article considers a medical interpretation for the spinal-pelvic anomaly in the anatomy of one of the boys.The artist has depicted a combination of structural anatomical adjustments diagnostic of spondylolisthesis, a forward slippage of one of the lumbar vertebrae. The accurate portrayal of the surface appearance of this condition suggests that the artist painted directly from a live subject. Thus, the Boxing Boys mural may be the earliest visual record of a sports-induced injury. Although the meaning of the wall paintings is unclear, the wild goats (agrimia) on the adjoining walls simulate swayback as a reflection of the boy's torso deformity and share other features with the boxers, adding to the unifying characteristics of the room. The abnormal morphology appears to be the earliest achievement of transforming disease into aesthetic charm on a monumental scale.  相似文献   

18.
Malcolm J.  Coe 《Journal of Zoology》1967,151(3):313-321
Previous references to "necking" behaviour, and the main features of the study area are briefly outlined.
"Necking" behaviour in giraffe takes place only in all male herds. When the animals are in a head to head posture the intensity is either high or low, but when animals take up a head to tail posture the actions are always of high intensity and appear to have greater sexual significance.
The significance of "necking" is discussed, and it is suggested that these ritualized actions form an important sexuo-social bonding mechanism whereby a hierarchy is created amongst the males, and movement between strictly bachelor and mixed herds helps to maintain contact between the sexes in this polygamous mammal.  相似文献   

19.
20.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号