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p16(MTS-1/CDKN2/INK4a) in cancer progression   总被引:52,自引:0,他引:52  
Since its discovery as an inhibitor of cyclin-dependent kinases 4 and 6, the tumor suppressor p16 has continued to gain widespread importance in cancer. The high frequency of deletions of p16 in tumor cell lines first suggested an important role for p16 in carcinogenesis. This initial genetic evidence was subsequently strengthened by numerous studies documenting p16 inactivation in kindreds with familial melanoma. Moreover, a high frequency of p16 gene alterations was found in primary tumors, while recent studies have identified p16 promoter methylation as a major mechanism of tumor-suppressor-gene silencing. Additional insight into p16's role in cancer has come from the genetic analysis of precancerous lesions and various tissue culture models. It is now believed that loss of p16 is an early and often critical event in tumor progression. Consequently, p16 is a major tumor-suppressor gene whose frequent loss occurs early in many human cancers.  相似文献   

3.
The Brazilian Federal Senate created a Parliamentary Inquiry Commission (CPI) to investigate the Bolsonaro government's irregularities in the management of the COVID-19 pandemic. One of the cases that drew attention was the research conducted by Prevent Senior, a private health insurance company, on the early treatment of COVID-19. The article analyzes the scientific validity of the research and the ethical problems related to its implementation. It is based on analysis of Prevent Senior's report of the clinical study, the Brazilian and USA clinical trial registries, the Senate's CPI report, and on the information reported by the media. This case of scientific fraud and political-ideological bias exemplifies how Prevent Senior, using a questionable protocol to enhance its reputation and gain government support, was instrumental in building the “early treatment” narrative for COVID-19, and shows how it served as a basis for a government public policy that promoted the use of ineffective drugs.  相似文献   

4.
This article examines how photographs showing Nilgiri people were brought back to France and deposited at the Museum national d'histoire naturelle in 1872. This leads me to recall the circumstances of a scientific mission made by the French astronomer Jules Janssen in South India in 1871. The paper throws light on the sources and on the personal experience of his wife, who published an ethnographic article in 1882. The importance of photography in the activities and achievements of Jules Janssen was well known. However the snapshots he brought back are better appraised in the context of the beginnings of photography and the development of its practice in British India. This case also illustrates the relations between photography and physical anthropology.  相似文献   

5.
Since ancient times comparisons between embryonic forms of humans, animals, and plants are known. In deciphering a plant embryo and its development, one applied a specific zoomorphic terminology. Until the 17th century naturalists who studied plants were inspired by the concepts of ancient natural philosophy. Since then plant embryos are visualized by drawings and diagrammatic sketches. In the 18th century the embryo became an important issue in debates concerning theories of generation and the analogy between animal egg and vegetable seed was emphasized. Due to the cell theory and refined microscopic techniques around 1850 botanists described the 'plant embryo' as an aggregate of cells. The 20th century profited of further technical improvements, e.g. microphotography, SEM, and plant tissue culture. The spell of the word embryo integrated morphological and morphogenetic data in botany and served as a code to decipher botanic forms. The paper presents a short history of the concept of 'plant embryo' and focuses on its distinct meanings over centuries, supported by different images.  相似文献   

6.
The history of science is an important component to acquire for achieving scientific literacy. In this study, a collaborative activity was applied in which the students were presented with the historical context in which Robert Hooke lived and developed the first register of the microscopic world. Furthermore, the students explored the environment using a microscope made by themselves, employing PET bottles and lenses obtained from CD or DVD readers and, finally, they drew and described selected objects, and collaboratively rewrote a ‘new version’ of Hooke’s classical book ‘Micrographia’. The study was performed in a secondary school, with 12- to 15-year-old students, and the hypothesis was that the planned intervention could enlarge students’ perception of historical aspects of the scientific discovery of the microscopic world, to a greater extent than traditional classes involving lectures and textbooks. The comparison was evaluated using a quantitative tool, called the History-Word-Association test (HWAT), which aims to evaluate the general vision of students regarding the agents, historical period and sociocultural circumstance involved in the issue addressed. The students that participated in the planned didactic activity showed a significant improvement in identification and retention of ideas associated with the history of the discovery of the microscopic world.  相似文献   

7.
Transconjunctival upper blepharoplasty is a novel technique for which the overall experience has been limited. The authors have used this technique in 42 patients for eyelid rejuvenation, with predictable results and low morbidity. The authors previously described the "bare" area in the medial upper conjunctiva, which was initially noted during their clinical series. This area serves as an anatomic window to access the medial upper eyelid fat pad with a high degree of safety. To clarify the anatomy of this approach, an anatomic study of the upper medial eyelid was performed on the orbits of 10 cadavers (20 orbits). The bare area was further elucidated during these dissections and its microscopic components described in detail. Its spatial relationship to the medial orbital wall and trochlea was also examined during this study. The authors hope that these findings will aid surgeons planning to use this technique.  相似文献   

8.
自英国生态学家查尔斯.艾尔顿1958年撰写的《动植物的入侵生态学》出版至今,半个世纪已经过去,这部著作被公认为是生物入侵在科学研究方面的开端。这期间生物入侵研究经历了萌芽期(20世纪80年代之前)、成长期(20世纪80年代)和快速发展期(20世纪90年代末期至今)。在这个过程中,越来越多的概念、假说、方法和技术被提出和整合到生物入侵研究之中,由此催生了一门生态学领域的新兴学科——入侵生物学。本文在对近50年来生物入侵专著和论文的统计分析基础上,介绍了国际生物入侵研究的发展脉络和现状。同时综述了中国入侵生物学在基础和应用研究方面的相关进展,着重阐述了主要科学问题("入侵潜力与成功入侵的关系"、"入侵种种群的扩张与扩散"、"入侵种的生态适应性与进化"及"本地生态系统对入侵的响应及可入侵性")和预防与控制的技术体系(风险评估与早期预警、检测与监测、狙击与灭除、生物防治、生态修复与干扰调控),并进一步介绍了中国入侵生物学学科体系的构建和框架,提出入侵生物学是研究外来物种的入侵性与生态系统的可入侵性,以及外来物种预防与控制的科学,是一门多领域交叉的学科。最后展望和讨论了中国入侵生物学学科发展可能遇到的一些问题。  相似文献   

9.
I give an historical account and analysis of the scientific priority of the discovery of the polychrome staining of microscopic biological preparations provided by mixtures of eosin plus methylene blue and its derivatives, especially azure B. I maintain that both the formal priority for the discovery of the polychrome staining phenomenon and credit for initiating the development of a technique of polychrome staining properly belong to D. L. Romanowsky. His scientific work demonstrated the possibility of using a simple technique to stain hematological preparations selectively to give good contrast, high resolution and the ability to identify malaria parasites. Romanowsky’s approach constituted the starting point for the development of a family of polychrome stains for microscopic investigation of hematological preparations by a number of his contemporaries.  相似文献   

10.
John G. Charles 《BioControl》2012,57(5):619-626
Release of a biocontrol agent in New Zealand is typically preceded by non-target testing of native or valued species. Nevertheless, if both the target pest and the natural enemy are very different from any native fauna, then there may be no scientific justification for host testing. Gonatocerus ashmeadi (Girault) (Hymenoptera: Mymaridae) is being considered as a biocontrol agent for glassy winged sharpshooter, Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae), should the pest arrive. An assessment of the potential impact of G. ashmeadi on New Zealand’s Cicadellidae and Membracidae, from published literature data, indicates that none of these insects is at risk, as their eggs will not be recognised by the parasitoid because either their size or location places them outside the parasitoid’s search pattern. Consequently, there is no scientific case for any non-target host-testing to be carried out in containment.  相似文献   

11.
Summary Scientific photography is an important facet of plant tissue culture. The aim of photography in plant tissue culture should be to illustrate clearly the developmental stages occurring in vitro. However, the photographic results presented in publications are often poor, and morphogenetic responses are often not clearly documented. Plant tissue culture is a very visual science, and the valuable tool of photography is often not used properly. If the morphogenetic responses are not well documented, an important part of the reserch is missed, and the report ends up having limited scientific value. Simple methods for improving the results of photography in plant tissue culture are discussed, along with photographic equipment, photomacrography, stereophotomicrography, suitable backgrounds for photography, use of a digital scanner, and the construction of photographic plates.  相似文献   

12.
Electron microscopic radioautography was used to study the osteogenesis during the replacement of bone tissue defects by graded distraction osteosynthesis in 12 patients with open fractures of the tibia. In the early stages of reparative tissue formation, the cells that intensely synthesized DNA and DNA were located exceptionally in the vascular walls or near them. The authors assume that vascular cells, most probably pericytes, are a basic source of the origin of the reparative tissue, turning firstly to fibroblast-like cells and then to osteoblasts.  相似文献   

13.
Friedrich von Huene’s important scientific research on tetrapod fossils from Central Brazil has received little attention, even though it represents a significant contribution to early studies of vertebrate paleontology in the country including the first discoveries of dinosaur fossils in Brazil. von Huene described five reptile taxa in two papers published in important German scientific journals and used these specimens to make paleogeographic inferences regarding the Cretaceous of the Southern Hemisphere. von Huene warrants recognition as the first specialist to describe in detail the fossil reptile fauna of Central Brazil, which was made possible only by his network of contacts with important and influential naturalists of the cities of Rio de Janeiro and São Paulo.  相似文献   

14.
John T. Mickel 《Brittonia》1996,48(3):386-388
The New York Botanical Garden has had only two fern curators: L. M. Underwood (1896–1907) and J. T. Mickel (1969-present). Both curators published milestone manuals on the North American ferns and conducted research on tropical American pteridophytes. After Underwood’s death. J. K. Small, though not a fern curator, published manuals on the ferns of New York and the southeastern United States. The current fern program is a broad one, involving the herbarium, horticulture, and outside support groups.  相似文献   

15.
The need to support bioinformatics training has been widely recognized by scientists, industry, and government institutions. However, the discussion of instructional methods for teaching bioinformatics is only beginning. Here we report on a systematic attempt to design two bioinformatics workshops for graduate biology students on the basis of Gagne's Conditions of Learning instructional design theory. This theory, although first published in the early 1970s, is still fundamental in instructional design and instructional technology. First, top-level as well as prerequisite learning objectives for a microarray analysis workshop and a primer design workshop were defined. Then a hierarchy of objectives for each workshop was created. Hands-on tutorials were designed to meet these objectives. Finally, events of learning proposed by Gagne's theory were incorporated into the hands-on tutorials. The resultant manuals were tested on a small number of trainees, revised, and applied in 1-day bioinformatics workshops. Based on this experience and on observations made during the workshops, we conclude that Gagne's Conditions of Learning instructional design theory provides a useful framework for developing bioinformatics training, but may not be optimal as a method for teaching it.  相似文献   

16.
Histochemical methods for microscopic visualization of mammary myoepithelial cells all yielded considerable variation in completeness of myoepithelial cell staining. Although extremely variable, silver impregnation occasionally gave tissue sections containing myoepithelia having excellent microanatomical detail and contrast with other tissue elements. Consequently, sources of variation in the silver technique were considered. Composition of the tissue fixative and pH of the silver impregnating solution were most critical. A final method is presented which gives consistent, complete silver impregnation of myoepithelia, where both the cell body and cell processes are clearly evident. The staining procedure is not light sensitive, nor is acid cleaning of glassware necessary. Tissue sections from lactating mouse, rat, hamster and goat are presented; tissue from other species should stain as well. The procedure should greatly facilitate the study of the function of myoepithelial cells and the visualization of these cells in mammary pathology.  相似文献   

17.
Summary New applications for photography in the scientific illustration of plants are offered by digital image manipulation, but have, to date, been little exploited. The evolving role of photography in botanical illustration is discussed, with particular emphasis on recently developed techniques of digitally created composite illustrations, their benefits and the potential of such images for further development. The technique is seen as a natural development of the composite watercolour or line illustrations that are familiar to all botanists.  相似文献   

18.
Histochemical methods for microscopic visualization of nummary myoepithelial cells all yielded considerable variation in completeness of myoepithelial cell staining. Although extremely variable, silver impregnation occasionally gave tissue sections containing myoepithelia having excellent microanatomical detail and contrast with other tissue elements. Consequently, sources of variation in the silver technique were considered. Composition of the tissue fixative and pH of the silver impregnating solution were most critical. A final method is presented which gives consistent, complete silver impregnation of myoepithelia, where both the cell body and cell processes are clearly evident. The staining procedure is not light sensitive, nor is acid cleaning of glassware necessary. Tissue sections from lactating mouse, rat, hamster and goat are presented; tissue from other species should stain as well. The procedure should greatly facilitate the study of the function of myoepithelial cells and the visualization of these cells in mammary pathology.  相似文献   

19.
Although the field of protein methylation enjoys widespread interest in the scientific literature of today, this is a recent phenomenon. Papers on 'protein methylation' were first published in the 1960s. By the early 1980s, it was known that lysine, arginine, histidine and dicarboxylic amino acids were post-translationally methylated by highly specific methyltransferases. However, despite these early advances, the biological importance of these reactions remained largely unproven. With the introduction of modern molecular biology techniques in the mid-1990s, an enormous surge of interest in protein methylation occurred. It is now clear that protein methylation carries many important biological functions, including gene regulation and signal transduction. Thus, the story of protein-methylation research is a testament to both modern molecular biology and the importance of continuing to pursue lines of research in which the precise biological function might not be currently known.  相似文献   

20.
At age 80, Antony van Leeuwenhoek was a world-famous scientist who came from a prosperous Delft family with a heritage of public service. He continued that tradition by serving in paid municipal offices. Self-taught, he began his scientific career in his 40s, when he began making hundreds of tiny single-lens microscopes. Pioneering the use of now-common microscopic techniques, he was the first human to see microbes and microscopic structures in animals, plants, and minerals. Over 50 years, he wrote only letters, more than 300 of them, and published half of them himself. More than a hundred were published in translation in the Royal Society’s Philosophical Transactions. Today, Leeuwenhoek is considered in the lesser rank of scientists and is not well known outside of his homeland. Recent archival research in Delft has contributed new information about his life that helps to contextualize his science, but much remains to be learned.  相似文献   

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