Model for Intravital Microscopic Evaluation of the Effects of Arterial Occlusion-caused Ischemia in Bone

An in vivo model has been developed for chronic observation of the effects of ischemia on cortical bone remodeling and perfused vascularity. Diaphragm occluders were implanted around the right common iliac artery of four rabbits and inflated to produce 10 h of ischemia to the limb. Microcirculation was monitored with intravital microscopy of injected fluorescent microspheres and FITC-Dextran 70 through a bone window, the tibial bone chamber implant (BCI). Bone resorption and apposition in the BCI were indicated with mineralization dyes. Between 2 and 12 h following release of the occluder, secondary ischemia/no-reflow and other evidence of reperfusion injury were observed. Vessel damage was suggested by abnormally high leakage of FITC-D70 from the few vessels perfused during secondary ischemia. In the weeks following occluder release perfused vasculature increased beyond pre-occlusion levels. Net bone resorption reached a maximum when vascularity passed normal levels. In order to further validate the arterial occlusion model for osteonecrosis, techniques for (1) confirming bone death and (2) detecting increased leukocyte adherence to endothelial cells were added. The dead cell stain Ethidium homodimer-1 was used to tag dead osteocytes immediately after occlusion and produced a measure designated osteonecrosis index. To detect leukocytes adhering to vessel walls, carboxyfluorescein diacetate, succinimidyl ester was injected at occluder release. An increase in the number of adherent leukocytes was detected. © 1999 Biomedical Engineering Society. PAC99: 8764Rr, 8717-d, 8719Tt     

3D MRI-Based Multicomponent FSI Models for Atherosclerotic Plaques

A three-dimensional (3D) MRI-based computational model with multicomponent plaque structure and fluid-structure interactions (FSI) is introduced to perform mechanical analysis for human atherosclerotic plaques and identify critical flow and stress/strain conditions which may be related to plaque rupture. Three-dimensional geometry of a human carotid plaque was reconstructed from 3D MR images and computational mesh was generated using Visualization Toolkit. Both the artery wall and the plaque components were assumed to be hyperelastic, isotropic, incompressible, and homogeneous. The flow was assumed to be laminar, Newtonian, viscous, and incompressible. The fully coupled fluid and structure models were solved by ADINA, a well-tested finite element package. Results from two-dimensional (2D) and 3D models, based on ex vivo MRI and histological images (HI), with different component sizes and plaque cap thickness, under different pressure and axial stretch conditions, were obtained and compared. Our results indicate that large lipid pools and thin plaque caps are associated with both extreme maximum (stretch) and minimum (compression when negative) stress/strain levels. Large cyclic stress/strain variations in the plaque under pulsating pressure were observed which may lead to artery fatigue and possible plaque rupture. Large-scale patient studies are needed to validate the computational findings for possible plaque vulnerability assessment and rupture predictions.     

寰椎的解剖学测量及其临床意义

目的　探讨寰椎因素致椎 基底动脉供血不足的发病机制及手术切开横突孔减压提供解剖学依据。方法　在5 0例中国成年人干燥寰椎标本上 ,对具有临床意义的数据进行解剖学测量。结果　寰椎横突孔与椎动脉沟的成角左侧为(6 7 87± 5 39)°,右侧为 (6 9 84± 4 5 5 )° ;椎动脉沟绕寰椎侧块成角 :左侧为 (6 2 4 6± 4 6 6 )°,右侧为 (6 3 6 1± 2 31)°。寰椎横突孔前壁厚度 :左侧为 (2 96± 0 5 4 )mm ,右侧为 (3 2 1± 0 4 0 )mm。横突孔后壁厚度 :左侧为 (2 2 8± 0 5 7)mm ,右侧为 (2 0 2± 0 2 6 )mm。以上数据左、右侧比较差异无显著性。结论　椎动脉行经在寰椎横突孔与椎动脉沟内时 ,在骨性结构上有明显的两个成角 ,即横突孔与椎动脉沟的成角和椎动脉沟绕过侧块的成角 ,椎动脉的这两个成角增加了血液循环的阻力 ,同时在头颈部旋转运动时 ,椎动脉与骨性成角间更加贴近 ,这两个成角与椎 基底动脉供血不足的发生有关。寰椎横突孔后壁较前壁薄 ,此数据可作炒寰椎横突孔后壁切开减压时手术参考依据     

膝关节动脉的血液供应

本文通过动脉灌注,对120侧不同年龄(新生儿至87岁)尸体的膝关节骨性部和软组织的血液供应分别进行了研究。新生儿的膝动脉在软骨内分布呈节段性,软骨骨化后,骨骺和髌骨的动脉间建立广泛的吻合。骺软骨板分隔膝关节的骨骺与干骺端。随骺板的闭合,两者间有血管互相交通。骺板的血液供应来自骺动脉、干骺动脉和滋养动脉终末的毛细血管袢以及骨膜动脉网的小支。髌骨的动脉分3组,发自髌前丛和髌周动脉环。滑膜和髌下脂垫的血管分布丰富。肌睫和韧带在骨的附着处缺乏血管。成人半月板外1/5有血管分布,内4/5无血管。本文对膝关节血管分布的临床意义作了简要讨论。     

Extra- and intracellular free iron and the carotid body responses

The hypothesis that chelation of free iron, by decreasing reactive oxygen species (ROS), might mimic hypoxia and stimulate the carotid body was tested. We used the iron chelators, desferrioxamine (DFO, 200-400 microM) initially, and later ciclopirox olamine (CPX, 2.5-5.0 microM), on rat carotid body in vitro and measured chemosensory activity and [Ca2+]i in isolated cultured glomus cell clusters during normoxia and hypoxia. Although acute treatment of DFO might not penetrate the cell, and extracellular DFO would not influence these activities whereas CPX significantly increased chemosensory activities as well as increased [Ca2+]i in normoxia. We concluded that chelation of extracellular free iron did not alter ROS formation and oxygen sensing. Chelation of intracellular free iron and, therefore, a decrease in intracellular ROS appears to influence oxygen sensing in the carotid body.     

Variations of the origin of the artery of the sinoatrial node in normal human hearts

Summary The artery of the sino-atrial node was studied in 100 normal human hearts after injection of each coronary artery with coloured gelatine containing a radiopaque substance. The hearts belonged to 69 males and 31 females, being 64 Caucasians and 36 non-Caucasians (Negroes and Mulattoes) whose age ranged from 7 to 80 years. Since the individuals had committed suicide or were victims of accidents, their hearts, after pathologists' evaluation, were considered normal. The sinoatrial node of the normal human heart is supplied by the right coronary artery more frequently (58%±4.9% of the cases) than by the left (42%±4.9). The right anterior medial atrial artery, originating from the right coronary at the level of the medial third of the right anterior quadrant of the atrial dome, is most frequently (50%±5) responsible for the blood supply of the sinoatrial node. Among the branches of the left coronary artery, the left anterior medial atrial artery, originating at the level of the medial third of the left. anterior quadrant of the atrial cupola, was the most frequent blood supplier (25%±4.3) of the sinoatrial node. The origin of the artery of the sinoatrial node from the proximal portion or trunk of the left coronary artery was less frequent (12%±3.2) than the origin from the circumflex artery (30%±4.5). Neither sex nor race influenced the variations of the origin of the sino-atrial node.

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Variations d'origine de l'artère du noeud sinu-atrial du coeur humain normal

Résumé L'a. du noeud sinu-atrial a été étudiée sur 100 coeurs humains normaux après injection de chaque a. coronaire à la gélatine colorée additionnée d'une substance radio-opaque. Les coeurs provenaient de 69 hommes et 31 femmes, 64 caucasiens et 36 non caucasiens (nègres et mulâtres) âgés de 7 à 80 ans. Ces sujets étant décédés par suicide ou des suites d'accidents, leurs coeurs ont été considérés comme normaux après examen anatomo-pathologique. Le noeud sinu-atrial du coeur humain est vascularisé par l'a. coronaire droite plus fréquemment (58 %±4,9) que par l'a. coronaire gauche (42 %±4). L'a. atriale antéro-médiale droite, issue de l'a. coronaire droite au niveau du tiers médial du quadrant antérieur droit du dôme atrial est l'artère la plus fréquemment en cause (50 %±5) dans la vascularisation du noeud sinuatrial. Parmi les branches de l'a. coronaire gauche, l'a. atriale antéro-médiale gauche, née au niveau du tiers médial du quadrant antérieur gauche du dôme atrial, était la branche la plus fréquemment en cause (25 %±4,3) dans la vascularisation du noeud sinu-atrial. La naissance de l'a. du noeud sinu-atrial à partir de la partie proximale ou du tronc de l'a. coronaire gauche était moins fréquente (12 %±3,2) que son origine à partir du rameau circonflexe (30 %±4,5). Les variations d'origine de l'a. du noeud sinu-atrial n'apparaissaient pas influencées par le sexe ou la race.

     

Two unusual benign lesions of the neck masquerading as malignancy on fine-needle aspiration cytology

Two cases of unusual benign tumors of the neck are described, both of which were initially misdiagnosed on cytology as carcinomas. Fine-needle aspiration findings in each case demonstrated a pleomorphic population of cells including bizarre multi-nucleated giant cells, the latter raising the false impression of malignancy. However, on review the cytological appearances of the tumors, a pleomorphic lipoma and a carotid body tumor, were characteristic. the correct diagnosis in each case would have been made or suggested if the pathologist had been familiar with the cytologic features characteristic of the lesion and the differential diagnosis of the head and neck tumors. in addition, the point is made that adequate clinical information is essential for the pathologist if all relevant conditions are not to be missed in the differential diagnosis.     

An association of 5,10-methylenetetrahydrofolate reductase (MTHFR) gene polymorphism and common carotid atherosclerosis

Plasma homocysteine (Hcy) concentration has been shown to be influenced by a mutation in the gene coding methylenetetrahydrofolate reductase (MTHFR). Although plasma Hcy is related to atherosclerotic disorders, conflicting results have been reported about the association between MTHFR gene polymorphism and sclerotic lesions of the common carotid arteries. The effect of age–gene interaction on carotid arterial remodeling was investigated in elderly subjects with several risk factors for atherosclerosis. We evaluated sclerotic lesions of the common carotid arteries by ultrasonography in 326 patients (mean age ± standard deviation, 73 ± 12 years) and studied relations among the known risk factors for atherosclerosis, including MTHFR gene polymorphism and its interactions with age and sex. Of the 326 subjects studied, 136 had MTHFR genotype CC, 136 genotype CT, and 54 genotype TT. The three groups did not differ with respect to background factors such as age, history of cigarette smoking, blood pressure, lipids or uric acid, or in the incidence of atherosclerotic diseases. Spearman's rank correlation revealed a significant relationship between gender, age, Brinkman index, systolic blood pressure, triglycerides, HDL-cholesterol (HDL-C), uric acid, and MTHFR gene polymorphism. Multiple regression analysis using intima-media complex thickness (IMT) as a criterion variable and risk factors, including MTHFR gene polymorphism as explanatory variables showed that MTHFR gene polymorphism (P = 0.039) was a significant independent explanatory variable for IMT, along with gender (male) (P < 0.001), age (P < 0.001), systolic blood pressure (SBP) (P = 0.047), total cholesterol (T-C) (P < 0.001), and HDL-C (P < 0.001). Furthermore, a general linear model analysis revealed that interaction between age and MTHFR gene polymorphism was significantly associated with IMT, independently of age, SBP, T-C, and HDL-C in male subjects. However, age–gene interaction was not observed in female subjects. The findings of the present study confirm an association between MTHFR gene polymorphism and common carotid atherosclerosis in the Japanese population and further support the role of risk factor–gene interaction in common carotid atherosclerosis. Received: May 14, 2001 / Accepted: June 8, 2001     

Chemoreceptor responses to substance P, physalaemin and eledoisin: Evidence for neurokinin-1 receptors in the cat carotid body

Substance P (SP) belongs to a group of peptides called tachykinins. Biological effects of SP are mediated by tachykinin receptors that have been classified as neurokinin-1 (NK-1), NK-2 and NK-3 subtypes. The aim of the present study is to elucidate the tachykinin receptor subtype(s) that mediate the excitatory effects of SP in the carotid body. For this purpose, we compared the carotid body responses elicited by SP with that of physalaemin and eledoisin. In other tissues, physalaemin exhibits equi or greater potency at NK-1 receptors and eledoisin exerts its effects more on NK-2 and NK-3 subtypes compared to SP. Experiments were performed on eight cats that were anaesthetized, paralyzed and artificially ventilated with room air. Close carotid body administration of SP and physalaemin produced dose-dependent augmentation of the chemoreceptor afferent activity. Chemoreceptor discharge, however, was unaffected by eledoisin. Compared to that by SP, the magnitude of excitation produced by physalaemin was the same at lower doses but significantly greater with the highest dose (100 nmol). The time course of the response induced by physalaemin, however, was the same as that by SP. The present results demonstrate that in the carotid body physalaemin is also either equi or relatively more potent than SP, whereas eledoisin has no effect on the chemoreceptor discharge. It is suggested that stimulation of the carotid body by SP is mediated by NK-1 but not NK-2 or NK-3 receptors.     

国人延髓动脉的观察

本文观察了110例成人脑标本的延髓外部动脉;采用动脉X线造影法和透明法,在20例人脑标本上观察了延髓内部动脉的形态和供应。将延髓表面分为四区,供应各区的外部动脉可分为相应的4群。前正中群和前外侧群动脉主要来自脊髓前动脉,前正中群动脉供应舌下神经核、内侧丘系及部分锥体束等中缝两侧结构;前外侧群动脉供应大部分锥体束;外侧群动脉来自椎动脉、小脑下后动脉、基底动脉和小脑下前动脉,主要供应网状结构、脊髓丘脑束、三叉神经脊束及核、迷走神经背核等;后群动脉来自脊髓后动脉和小脑下后动脉,主要供应薄、楔束核等。本文还讨论了延髓外侧区的血液供应及“终动脉”等问题。