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81.
The distal femoral growth plate has a uniquely convoluted structure comprised of four mammillate processes. Factors contributing to the development of these processes and overall plate geometry were explored using three-dimensional image analysis of the canine distal femoral epiphysis. The growth plate at birth remains relatively flat until ossification of the epiphysis begins at 1 week of age. Epiphyseal ossification proceeds eccentrically, projecting in the medial-lateral and anterior-posterior directions. Growth plate activity indexed by [3H]thymidine labeling and plate thickness revealed regional differences in cell proliferation. This was measured as a decreased labeling index and thinning of the growth plate in areas capped by the ossifying epiphysis. The eccentric ossification pattern and associated variations in growth plate activity result in definition of an "intraphyseal" groove and medial-lateral oriented sulcus. The groove and sulcus bisect the plate into four quadrants, giving rise to a convoluted structure composed of four areas of plate elevations termed mammillary processes (MP). By 5 weeks, the pattern of ossification results in greater development of the MP in the anterior-medial quadrant and in decreasing order, in the posterior-medial, anterior, and posterior-lateral quadrants. By 10 weeks, a uniform rate of cell proliferation was observed coincident with completion of ossification of the epiphysis. The data suggest that localized variations in growth plate proliferation are associated with ossification of the epiphysis.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
82.
目的评估AO肩锁钢板钩治疗重型肩锁关节脱位的手术疗效.方法回顾性分析两年来27例手术病人的手术治疗和疗效.结果手术方法符合生理结构,手术时间平均30分钟,内固定牢靠.根据Murley和Constant[1]评分,优良率94%.结论 AO肩锁钢板钩治疗重型肩锁关节脱位,手术方法简单,疗效可靠,允许病人术后早期功能锻炼. 相似文献
83.
84.
Deborah U Frank Sarah A Elliott Eon Joo Park Jennetta Hammond Yukio Saijoh Anne M Moon 《Developmental dynamics》2007,236(4):1085-1092
We targeted the reverse tetracycline controlled transactivator (rtTA) to the Foxa2 locus (Foxa2(ITA)) to generate a system for regulating Cre-recombinase activity within Foxa2 expression domains, including the endoderm, notochord, and floor plate of early mouse embryos. The use of an internal ribosomal entry site to obtain rtTA expression preserves Foxa2 function of the targeted allele. Cre activity with this system reflects the level of endogenous Foxa2 activity and is also tightly controlled by doxycycline. The location of Cre activity within the broader Foxa2 expression domain can be restricted by altering the timing of doxycycline administration. Isolated floor plate expression can be obtained in this manner. This system will provide a useful tool for manipulating gene expression in endoderm, notochord, and floor plate, all of which are tissues with important structural and patterning functions during embryogenesis. 相似文献
85.
Fluid Flow through Filtering Appendages of Insects 总被引:4,自引:0,他引:4
Many organisms use structures composed of arrays of cylindersto capture particulate food or molecules form the water or airaround them. The performance of such filters depends on thevelocity of fluid movement through them; hence, mathematicalmodels of flow through fibrous structures can provide insightsabout the functional morphology of biological filters. In thispaper, the authors address the case of feather-like biologicalfilters of finite width and assess several possible models forfluid motion through them by comparing model predictions withobservational data. Two examples of insect appendages are considered:the cephalic fans of black fly aquatic larvae that capture particulatefood and the antennae of adult male moths that catch sex-attractantmolecules released by female moths. The results suggest thatflow through such structures can be much slower than ambientcurrents, that the finest hairs in the structure are the morphologicalfeatures with the greatest effect on leakiness, and that thevelocity of movement (or of ambient flow), as well as the morphologyof such filters, can be critical in determining their performance. 相似文献
86.
87.
[摘要] 目的 对比分析人工肱骨头置换术和肱骨近端锁定钢板治疗老年复杂肱骨近端骨折的近期疗效。方法 回顾性分析本院骨科2012年1月~2014年6月采用人工肱骨头置换术和肱骨近端锁定钢板治疗的老年(年龄>65岁)NeerⅢ、Ⅳ部分肱骨近端骨折患者54例,人工肱骨头置换治疗(置换组)30例,肱骨近端锁定钢板内固定治疗(内固定组)24例。比较分析两组手术时间、术中出血量、随访Neer评分及Constant-Murley评分来评定两组临床疗效。结果 两组随访时间相仿,平均随访时间为19.5个月(12~36个月)。内固定组手术时间(101±13)分钟,术中出血量(237.9±32.4)mL,Neer评分(82.5±3.2),Constant-Murley评分(71.7±5.0);置换组手术时间(98±11)分钟,术中出血量(246.0±39.8)mL,Neer评分(82.9±4.5),Constant-Murley评分(73.5±5.0)。两组手术时间、术中出血量、随访Neer及Constant-Murley评分比较差异均无统计学意义(P>0.05)。内固定组有1例出现肩关节半脱位,肱骨头置换组有2例出现肩关节半脱位,通过三角巾悬吊后关节脱位均得到纠正。有1例四部分骨折患者,行内固定术后出现内固定松动、肱骨头坏死,改行人工肱骨头置换术。结论 人工肱骨头置换术和肱骨近端锁定钢板治疗老年肱骨近端复杂骨折的近期临床疗效相似,对不可修复的肱骨近端骨折宜行肱骨头置换术。 相似文献
88.
Christoph Olbricht June Mason Toshikazu Takabatake Gero Hohlbrugger Klaus Thurau Sigrid Pätz 《Pflügers Archiv : European journal of physiology》1977,372(3):251-258
Summary Experiments were designed to determine whether leakage of substances across the tubular epithelium, which are impermeant in the normal kidney, falsifies the measurement of glomerular filtration rate in acute renal failure. Permeability to those substances most commonly used for filtration rate determination, polyfructosan, inulin and ferrocyanide, was estimated by measuring their recoveries following perfusion through various nephron segments in haeme pigment, ischaemic and nephrotoxic models of actue renal failure. Late proximal recovery of14C ferrocyanide was only marginally decreased compared to controls, by a maximum of 6%. Distal recovery of polyfructosan,14C and3H inulin were depressed somewhat more, by a maximum of 11%. Urinary recovery of14C inulin was reduced by only 15% in kidneys showing severely restricted renal function. It is concluded that tubular leakage is not a feature of significance in the early phase of moderate acute renal failure, that ferrocyanide and inulin are reliable markers for the determination of nephron filtration rate and water reabsorption, and that the reduction in whole kidney inulin or polyfructosan clearance reflects primarily a reduction in glomerular filtration rate. 相似文献
89.
作者自1994年始采用自行设计L形钢板内固定治疗不稳定股骨粗隆间骨折60例,平均随访25个月,X线片显示骨折愈合时间6~13周,平均8.9周,伤肢功能在3个月内基本恢复正常,无骨折延迟愈合及髋内翻现象。为论证改良L形钢板的优点,本文采用8具新鲜尸股骨沿着它的外侧、内侧骨皮质粘贴6个应变片,观察股骨近端应变和位移分布,以检验改良L形钢板固定粗隆间骨折的效果。在实验前后将股骨粗隆造成二部分或四部分骨折。利用实验结果给制成应变和位移图,并与鹅头打固定组相比较。在载荷加至1800N时比较两种内固定器械的生物力学性能。结果表明,在治疗不稳定粗隆间骨折中,L形钢板比鹅头钉更具有生物力学的优势。 相似文献
90.
目的总结桡骨远端粉碎性骨折的外固定架治疗疗效。方法从1995年~2003年采用外固定架治疗桡骨远端粉碎性骨折46例,并进行随访。结果治疗后均随访1年,术后按Dienst评分,优良率为83.3%。结论外固定架固定牢靠,可早期活动腕关节,是治疗桡骨远端粉碎性、开放性骨折的有效方法。 相似文献