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排序方式: 共有11条查询结果,搜索用时 15 毫秒
1.
We attempted a new approach based on a modern dynamical system theory to reconstruct the arterial blood pressure signals in relation to heart rate fluctuations of developing chick embryos. The dynamical systems approach in general is to model a phenomenon that is presented by a single time series record and approximate the dynamical property (e.g. heart rate fluctuations) of a system based only on information contained in a single-variable (arterial blood pressure) of the system. The time-series data of the arterial blood pressure was reconstructed in 3-dimensional space to draw characteristic orbits. Since the reconstructed orbits of the blood pressure should retain information contained in the pressure signals, we attempted to derive instantaneous heart rate (IHR) from the reconstructed orbits. The derived IHR presenting HR fluctuations coincided well with the IHR obtained conventionally from the peak-to-peak time intervals of the maximum blood pressure. Movements of the reconstructed orbits of the arterial blood pressure in 3-dimensional space reflected HR fluctuations (i.e. transient decelerations and accelerations).  相似文献   
2.
本文对236例(472侧)中国成人颅骨的脑膜中动脉眶支沟、脑膜中动脉眶支孔和眶外侧沟进行了观察。主要结果如下:脑膜中动脉眶支孔的出现率为55.9%;眶外侧沟的出现率为17.6%,其中双侧出现的有24例,占10.2%。  相似文献   
3.
An evaluation of the location of the infraorbital foramina in a transverse plane was undertaken by direct skull and radiographic measurements in unrepaired cleft palate and age- and sex-matched noncleft individuals. Physioprints were obtained on six dry skulls with left-sided clefts of the primary and secondary palates and on six age- and sex-matched noncleft palate skulls. The left infraorbital foramen was found to be significantly superior in a transverse plane to the right infraorbital foramen in the cleft palate skulls. No significant differences in transverse location of the infraorbital foramina were found in the cleft skull group based on differences in sex or age. Posterior-anterior cephalographs were obtained on 15 left unilateral cleft palate individuals and on age- and sex-matched noncleft palate individuals. The location of the infraorbital foramina in a transverse plane in the posterior-anterior cephalographs was found to be too variable to permit the use of parametric statistical tests. When the data on location of the infraorbital foramina were analyzed by a nonparametric statistical test it was found that the left infraorbital foramen was significantly superior to the right infraorbital foramen in the cleft palate individuals. The more superiorly placed infraorbital foramen on the cleft side was suggestive of a vertical deficiency of the maxilla on the cleft side.  相似文献   
4.
Ultrastructure of cultured human orbital fibroblasts   总被引:2,自引:0,他引:2  
The fine structure of cultured human orbital fibroblasts was investigated by transmission electron microscopy. One culture was derived from a patient with severe Graves' ophthalmopathy, the other from a donor without inflammatory orbital disease. Despite their known differences in metabolism, orbital fibroblasts from either source revealed no ultrastructural differences. The cells had extensive thin cytoplasmic processes. The perinuclear areas contained multiple assemblies of Golgi membranes, modest amounts of rough endoplasmic reticulum, intermediate filaments, and lysosome-like structures. Glycogen deposits were noted both in the perinuclear cytoplasm and in the thin processes. These ultrastructural features of orbital fibroblasts are the same as those of fibroblasts from other anatomic regions.  相似文献   
5.
According to the “nocturnal visual predation hypothesis” (NVPH), the convergent eyes and orbits of primates result from selection for improved stereoscopic depth perception to facilitate manual capture of prey at night. Within primates, haplorhines share additional derived orbital morphologies, including a postorbital septum and greater orbital convergence than any other mammalian clade. While the homology and function of the haplorhine septum remain controversial, experimental data suggest that septa evolved to inhibit mechanical disturbance of the orbital contents by the anterior temporalis muscle during mastication. According to this “insulation hypothesis,” haplorhines are particularly susceptible to disruption of the orbital contents because they have large and highly convergent eyes and orbits. However, comparative tests of the insulation hypothesis have been hindered by the morphological uniqueness of the haplorhine septum among mammals. Among birds, owls (Strigiformes) exhibit an expanded postorbital process that may be functionally analogous to the haplorhine septum. Here we present a comparative analysis of orbital morphology in 103 avian species that tests two hypotheses: (1) large, convergent orbits are associated with nocturnal visual predation, and (2) the strigiform postorbital process and haplorhine postorbital septum similarly function to insulate the eyes from contractions of mandibular adductors. Strigiforms, as nocturnal visual predators, possess relatively large orbits and exhibit the highest degree of orbital convergence in our sample. Notably, orbital convergence does not scale with orbit size in birds as in mammals. Owls are also unique among the birds examined in possessing extensive, plate-like postorbital processes that largely isolate the orbits from the temporal fossae. Furthermore, dissections of four owl species demonstrate that the expanded strigiform postorbital process deflects the path of mandibular adductors around the eye's inferolateral margin. These findings provide further comparative support for both the NVPH and the insulation hypothesis.  相似文献   
6.
差异分析对于揭示生命体的生长、发育和衰老过程及疾病发生具有重大的意义,基于网络的差异分析方法已经成为系统生物学的一个研究热点。网络节点往往通过与局部结构作用实现某种功能,其与局部结构的关系变化,很可能影响其功能。本文利用仿真实验的方法比较了图元向量和点的聚类系数两种局部结构测度的性能,并且利用他们分别设计算法挖掘差异网络中模块化变化的基因簇。应用AGEMAP数据库中小鼠12个组织基因表达数据进行实验,大部分聚类簇都高度显著富集与衰老相关的GO项。  相似文献   
7.
In 6 of 17 skulls of Indri indri retaining distinct sutures in the medial orbital wall, a small separate bony element intervenes between the frontal and the maxillolacrimal suture. This element is demonstrably continuous with the ethmoid on one such skull. The occurrence of an ethmoid exposure in the orbit of Indri suggests that this trait is not a simple function of orbital size and convergence. Since such an exposure is found in non-cheirogaleine lemuriforms, its distribution provides no support for the hyothesis that lorises and galagos are derived from cheirogaleines.  相似文献   
8.
Among primates, nocturnal species exhibit relatively larger orbital apertures than diurnal species. Most researchers have considered this disparity in orbital aperture size to reflect differences in eye size, with nocturnal primates having relatively large eyes in order to maximize visual sensitivity. Presumed changes in eye size due to shifts in activity pattern are an integral part of theoretical explanations for many derived features of anthropoids, including highly convergent orbits and a postorbital septum. Here I show that despite clear differences in relative orbital aperture size, many diurnal and nocturnal primates do not differ in relative eye size. Among nocturnal primates, relative eye size is influenced by diet. Nocturnal visual predators (e.g., Tarsius, Loris, and Galago moholi) tend to have larger relative eye sizes than diurnal primates. By contrast, nocturnal frugivores (e.g., Perodicticus, Nycticebus, and Cheirogaleus) have relative eye sizes that are comparable to those of diurnal primates. Although some variation in orbital aperture size can be attributed to variation in eye size, both cornea size and orbit orientation also exert a strong influence on orbital aperture size. These findings argue for caution in the use of relative orbital aperture size as an indicator of activity pattern in fossil primates. These findings further suggest that existing scenarios for the evolution of unique orbital morphologies in anthropoids must be modified to reflect the importance of ecological variables other than activity pattern.  相似文献   
9.
Here we describe a detailed methodology to study the function of genes whose products function during mitosis by dsRNA-mediated interference (RNAi) in cultured cells ofDrosophila melanogaster. This procedure is particularly useful for the analysis of genes for which genetic mutations are not available or for the dissection of complicated phenotypes derived from the analysis of such mutants. With the advent of whole genome sequencing it is expected that RNAi-based screenings will be one method of choice for the identification and study of novel genes involved in particular cellular processes. In this paper we focused particularly on the procedures for the proper phenotypic analysis of cells after RNAi-mediated depletion of proteins required for mitosis, the process by which the genetic information is segregated equally between daughter cells. We use RNAi of the microtubule-associated protein MAST/Orbit as an example for the usefulness of the technique. Published: June 15, 2003  相似文献   
10.
《Cancer epidemiology》2014,38(5):515-522
Introduction: There is a wide range of tumors affecting the orbital adnexa. Key such tumors include lymphomas, carcinomas, melanomas and rhabdomyosarcomas. Several studies have proposed that these histological subtypes differ in their survival outcomes. In this study we aim to describe the difference in survival outcomes between such subtypes. Methods: The SEER database was used to gather patient information. All 18 SEER registries were used. Patients diagnosed from 1996 to 2005 were included in the analysis. Observed five-year survival rate was calculated using the SEER*Stat software version 8.1.2. Data were extracted into IBM SPSS version 20 to generate Kaplan Meier curve for each group. Results: There were 2180 patients in the SEER databases who met the selection criteria. Lymphomas were the most common histology in adults. The overall five-year observed survival for all lymphoma patients was 75.9% (95% CI: 73.7–78.1). There was statistically significant difference between observed survival rates of lymphoma subtypes. Carcinomas were the second most common tumors. Their five-year observed survival rate in our study was 60.4%. There was no statistically significant difference between carcinoma subtypes’ observed survival rates in the 20–49 age group, while, in the older age group, the difference was found to be statistically significant. Rhabdomyosarcomas were the most common tumors in children. The overall five-year observed survival rate for rhabdomyosarcomas patients was 89.8%. There was no statistically significant difference between observed survival rates of rhabdomyosarcomas subtypes. There was no statistically significant difference between relative survival rates according to gender and treatment received except within melanomas. Conclusion: In adults, lymphomas have better survival rates than carcinomas. Whereas the lymphoma subtype can be used as a determinant prognostic factor in any age, the carcinoma subtype can be used as such a determinant in older age groups only. In children, rhabdomyosarcomas are the predominant tumors affecting the orbital adnexa. Further studies are needed to determine if the difference between embryonal rhabdomyosarcoma and alveolar rhabdomyosarcoma observed survival rates are statistically significant.  相似文献   
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