Attenuation and speed of 10 MHz ultrasound in canine blood of various packed-cell volumes at 37°C

The attenuation coefficient and the speed of 10 MHz ultrasound were determined in canine blood at 37°C by a differential path-length technique. Blood specimens with packed-cell volumes (p.c.v) ranging from 0 to 53% were prepared by separating the cells from the plasma and mixing the two components. The mean attenuation coefficient increased linearly with packed-cell volume, the least squares regression function being α=0·992+0·039 PCV with a standard error of the estimate=0·255. The speed of 10 MHz ultrasound c in millimetres per second, increased with packed-cell volume, the regression function for a wave equation model being 1/c²=0·418+2·09×10⁻⁴ (PCV)−1·75×10⁻⁵ (PCV)² with a standard error of the estimate=0·0049 (mm/s)⁻². Both the attention coefficient and speed of 10 MHz ultrasound were greater in blood than in plasma to a degree dependent on the packed-cell volume.     

Spatial variation of aortic wall oxygen diffusion coefficient from transient polarographic measurements

Polarographic current transients following a voltage step (turn-on transient) were measured with bare cathodes (25 μm diameter) and shallowly recessed oxygen microelectrodes (<5μm diameter). Except for the initial part of the current transient, the experimental measurements were in excellent agreement with simple models in the literature, which predict an inverse relationship with . Turn-on transients were measured in aqueous solutions with known physical properties, and in aortic wall tissue from three different species (n=6 rabbits, n=3 dogs, and n=1 miniature pig). Oxygen diffusion coefficients (D) were determinedin vitro by comparing time constants measured by the same microelectrode in saline and in strips of aortic wall tissue at 37°C. On the inner side (endothelium and intima) of the aorta, D averaged (±S.E.) 7.0 (±0.8)×10⁻⁶ cm²/s in 6 rabbits, 6.4 (±1.0)×10⁻⁶ cm²/s in 3 dogs, and was 4.6×10⁻⁶ cm²/s in the pig. On the adventitial side, D was 9.5×10⁻⁶ cm²/s in 1 rabbit, 11.4 (±1.2)×10⁻⁶ cm²/s in 3 dogs, and 8.1×10⁻⁶ cm²/s in the pig. For every aortic strip on which D was measured from both sides, D for the inner wall was always lower, overall by a little more than one third (p<0.001). The lower D on the endothelial side may limit oxygen transport to the vascular wall and play a role in atherogenesis.     

Segmental aortic wall stiffness from intravascular ultrasound at normal and subnormal aortic pressure in pigs

Segmental aortic wall stiffness was calculated from intravascular ultrasound images and intravascular pressures in six pigs at normal and subnormal aortic pressures (21 sequences of pressures and areas before and after boli of intravenous nitroglycerin). The wall stiffness was expressed as the pressure–strain elastic modulus (E_p). The E_p was calculated from the formula: E_p=ΔPRΔR^-1 (P, pressure; R, radius) in two different ways. First from maximal and minimal values of pressure and area. Second as the slope of linear regression line of ΔPR as a function of ΔR from 29 simultaneous recorded pressures and images. The average E_p value for all sequences in the different segments was 0.58 ± 0.55 10⁵ Pa (Method 1) and 0.50 ± 0.40 10⁵ Pa (Method 2). E_p increased with the distance from the heart at normal aortic pressures. At subnormal aortic pressures after intravenous nitroglycerin this relationship was not so evident. At subnormal aortic pressures the calculated E_p values were significantly reduced in the lower half of the abdominal aorta. The phase lag, i. e. hysteresis, between pressure and diameter was demonstrated. Our study shows the applicability of intravascular ultrasound as a tool to evaluate arterial wall stiffness.     

Effects of formalin fixation, paraffin embedding, and time of storage on DNA preservation in brain tissue: a BrainNet Europe study

There is a large amount of tissue stored in brain collections and brain banks, but little is known about whether formalin-fixed tissues and paraffin blocks stored for years in brain banks are suitable for the retrospective genetic studies. The study was carried out in order to: (i) compare DNA preservation in frozen, formalin-fixed and paraffin-embedded tissues stored for different periods; (ii) study point mutations and triplet expansions in frozen, formalin-fixed and paraffin-embedded material stored for variable periods, and using different fixative solutions; (iii) compare different methods to optimize DNA extraction and DNA amplification from suboptimally preserved brain tissue. DNA preservation is suitable for genetic studies in samples stored at -80 degrees C for several years. Formalin-fixed, paraffin-embedded tissue was inferior to frozen tissue, but did yield adequate results in many cases depending on the type of fixative solution and time of fixation before embedding. Prolonged fixation in formalin rarely yielded useful DNA. Similar results were obtained in samples from prion diseases. The best results were obtained by using the Qiagen kits (QIAmp DNA Micro) in frozen material, paraffin blocks and formalin-fixed tissue. Genomiphi and TaKaRa Ex Taq methods were also assayed in paraffin blocks and in formalin-fixed samples with limited success.     

Interaction between the aortic valve leaflets and a Millar dual-micromanometer catheter during recording of the aortic component of the second heart sound in dogs

The influence of the closure of the aortic valve leaflets on a dual-micromanometer Millar catheter is investigated with respect to the power spectrum of the aortic component (A2) of the second heart sound in dogs. The catheter inserted through the aortic valve is used to simultaneously record A2 in the left ventricle and in the aorta and to study the transmission of A2 up to the body surface. Results indicate that the interaction of the valve leaflets with the Millar dual-micromanometer catheter during the closure and vibration of the aortic valve does not produce a clapping artefact. The main effect is a change in the natural modes of vibration (resonant frequencies) of the aortic valve resulting from a modification of the vibrating structure (combined structure composed of the catheter, the aortic valve and the surrounding blood and tissues) because of the tight mechanical coupling between the aortic valve leaflets and the catheter. In addition, this modification of the natural modes of resonance does not invalidate the estimation of the frequency response of the transfer function between the aortic root and the thoracic recording site, even if the mean gain of the transfer function is affected and the phase slightly increased with frequency. On the contrary, the interaction of the aortic valve leaflets with the catheter seems to slightly increase the spectral contribution (coherence) of the intra-aortic A2 to the thoracic A2.     

Dimensions of the aortic ring: An anatomical (84 cases) and surgical (439 cases) study

Summary The mean diameter of the aortic ring has been measured in twin anatomical (84 dissections), and surgical (439 aortic valvular replacements) studies. The values obtained (23.4 mm in females and 25.8 mm in males) are rather higher than those classically reported in the literature.The surgical series allowed us to obtain measurements of the aortic ring in relation to certain important factors, in particular body surface area and height. It is perhaps the progressive increase in mean height of Frenchmen that led to our measurements being greater than those previously described.

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Dimensions de l'anneau aortique. Etude de deux séries, anatomique (84 cas) et chirurgicale (439 cas)

Résumé Le diamètre moyen de l'anneau aortique a été précisé au travers d'une double étude, anatomique (84 dissections), et chirurgicale (439 remplacements mono-valvulaires aortiques): les valeurs observées (23,4 mm chez la femme, 25,8 mm chez l'homme) sont relativement importantes par rapport aux données classiques.La série chirurgicale a en outre permis d'interpréter ces valeurs en fonction de divers paramètres, notamment la surface corporelle et surtout la taille des sujets: peut-être l'augmentation de la taille de la population explique-t-elle les grandes dimensions observées.

     

Effects of formalin fixation and temperature on MR relaxation times in the human brain

Post‐mortem MRI of the brain is increasingly applied in neuroscience for a better understanding of the contrast mechanisms of disease induced tissue changes. However, the influence of chemical processes caused by formalin fixation and differences in temperature may hamper the comparability with results from in vivo MRI. In this study we investigated how formalin fixation and temperature affect T₁, T₂ and T₂* relaxation times of brain tissue. Fixation effects were examined with respect to changes in water content and crosslinking. Relaxometry was performed in brain slices from five deceased subjects at different temperatures. All measurements were repeated after 190 days of formaldehyde immersion. The water content of unfixed and fixed tissue was determined using the wet‐to‐dry ratio following drying. Protein weight was determined with sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE). Fixation caused a strong decrease of all relaxation times, the strongest effect being seen on T₁, with a reduction of up to 76%. The temperature coefficient of T₁ was lower in the fixed than unfixed tissue, which was in contrast to T₂, where an increase of the temperature coefficient was observed following fixation. The reduction of the water content after fixation was in the range of 1–6% and thus not sufficient to explain the changes in relaxation time. Results from SDS‐PAGE indicated a strong increase of the protein size above 260 kDa in all brain structures examined. Our results suggest that crosslinking induced changes of the macromolecular matrix are responsible for T₁ shortening and a decreased temperature dependency. The relaxation times provided in this work should allow optimization of post‐mortem MRI protocols for the brain. Copyright © 2016 John Wiley & Sons, Ltd.     

Surgery for acute aortic dissection using gelatin-resorcin-formalin glue: perspective from 10 years of follow-up at a single center

Acute type A aortic dissection is a lethal aortic disease with an extremely poor prognosis unless surgical intervention is performed in a timely manner. Since the clinical introduction of gelatin-resorcin-formalin (GRF) glue in Japan, tear-oriented aortic repairs have been widely performed with the aid of this glue at many institutions over the past decade. A total of 138 patients underwent glue-aided emergency operations for acute type A aortic dissection at Nihon University Itabashi hospital. The hospital mortality rate was 6.7%. The actuarial survival rate was 81.5% after 5 years and 54.8% after 10 years. The rate of freedom from reoperation was 87.9% after 5 years and 72.3% after 10 years. Although application of GRF glue remains controversial because of concerns about the cytotoxicity of formaldehyde and tissue necrosis, cytotoxicity and tissue necrosis have not been found at reoperation. GRF glue demonstrated excellent tissue adhesion and hemostasis capabilities and contributed to improved surgical results. Although some disadvantages have been reported, complications can be avoided by proper use of the glue and proper selection of surgical procedure, based on the pathology of the patient.     

Effects of magnesium sulfate on supraceliac aortic unclamping in experimental dogs

Intravascular administration of magnesium (Mg) causes vasodilation and increases renal blood flow. The aim of this study was to investigate the renal effect of Mg following unclamping of the supraceliac aorta. Mongrels were divided into two groups, control (group C, n=7) and Mg group (group Mg, n=7). In group Mg, 30 mg/kg MgSO4 was injected as a bolus immediately prior to unclamping the supraceliac aorta and thereafter as an infusion (10 mg/kg/hr). The group C received an equivalent volume of saline solution. Systemic hemodynamics, renal artery blood flow, renal cortical blood flow (RCBF), renal vascular resistance, and renal function were compared. Following the aortic unclamping, cardiac output and RCBF were less attenuated, and the systemic and renal vascular resistance was elevated to a lesser degree in the group Mg compared to the group C. There was no significant difference in the plasma renin activity, serum creatinine and Cystatin-C between the two groups. The present study shows that Mg infusion improves systemic hemodynamics and RCBF after aortic unclamping. However, we did not observe any improvement in renal function when Mg was administered after supraceliac aortic unclamping.     

Performance of the isolated,ejecting heart: effects of aortic impedance and exogenous substrates

The workload of the isolated, left-ventricular ejecting heart (i.e. working heart) is determined by the left atrial filling pressure and the afterload imposed on the left ventricular outflow tract. In addition to the level of end-diastolic aortic pressure, afterload is highly determined by the aortic impedance. For the isolated, ejecting heart optimum matching of the left ventricle to its afterload requires the highest possible similarity between the impedance of the artificial aortic conduit and the natural aortic impedance. The present study shows that the haemodynamic performance of the ejecting rat heart preparation can be affected by the impedance of the aortic conduit. A proper choice of substrates in the perfusion fluid further improves the performance of the heart in the artificial set-up. The present paper also provides guidelines with respect to the design of the aortic cannula and compliance chamber. The occurrence of turbulence, which is related to the Bernoulli pressure drop, is a major determinant of the impedance of the aortic conduit. This effect is used to simulate the natural resistance component of the aortic impedance. Further, the applicability of the perfusion model can be extended by the so-called assisted-mode perfusion, which allows automatic adjustment from antegrade to retrograde perfusion if the heart is not able to generate sufficient pumping power to provide its own coronary perfusion.Supported by NWO grant 900-516-091     

Effects of intra-aortic counterpulsation on aortic wall energetics and damping: in vivo experiments

Intra-aortic balloon pumping (IABP) could modify the arterial biomechanics; however, its effects on arterial wall properties have not been fully explored. This dynamical study was designed to characterize the pressure-dependent and smooth muscle-dependent effects of IABP on aortic wall energetics in an in vivo animal model. Intra-aortic balloon pumping (1:2) was performed in six anesthetized sheep in which aortic pressure and diameter signals were measured in basal, augmented (during balloon inflation), and assisted (postaugmented) beats. Energy dissipation values in augmented and assisted beats were significantly higher than those observed in basal state (p < 0.05). Assisted beats showed a significant increase of wall damping with respect to basal and augmented beats (p < 0.05). Intra-aortic balloon pumping resulted in a significant increase of pulse wave velocity (p < 0.05) in augmented beats with respect to basal state (6.3 +/- 0.8 vs. 5.2 +/- 0.5 m x s(-1)); whereas values observed in assisted beats were significantly (p < 0.05) lower than those observed in augmented beats (4.9 +/- 0.5 vs. 6.3 +/- 0.8 m x s(-1)). Our findings show that IABP determined the pressure and smooth muscle-dependent changes in arterial wall energetics and damping properties in this animal model.     

PPARγ在不同周龄apoE-/-小鼠主动脉斑块表达及与斑块成份的相互关系

目的:研究PPARγ基因表达与ApoE-/-小鼠主动脉斑块成份的相互关系。方法:以20和40周龄ApoE-/-小鼠(n=10/组)为研究对象,相同基因背景和周龄C57BL/6 J小鼠设为对照。采用RT-PCR和免疫印迹技术检测各组小鼠主动脉PPARγ基因和蛋白表达变化;Movat 5色套染法和油红O染色检测ApoE-/-小鼠主动脉斑块成份;免疫组织化学技术检测斑块内PPARγ、SM-actin、MOMA-2抗原表达。结合免疫荧光技术分析PPARγ基因在主动脉斑块巨噬细胞、平滑肌细胞的表达及与脂质、弹性纤维、胶原和蛋白聚糖的相互关系。结果:20和40周龄C57BL/6 J小鼠主动脉壁有少量PPARγ表达,以20周龄组明显。ApoE-/-小鼠主动脉壁和斑块内PPARγ表达增多,以斑块内表达明显(P<0.05);与20周龄组比较,40周龄组表达最显著;且斑块脂质含量丰富;弹性纤维、胶原和蛋白聚糖含量减少,血管正性重塑明显;MOMA-2表达增加,SM-actin表达降低(P<0.05)。PPARγ在斑块内巨噬细胞、血管中膜平滑肌细胞和斑块内平滑肌细胞都有表达,但以脂质含量丰富处PPARγ表达最明显。结论:PPARγ在C57BL/6 J小鼠动脉壁表达随增龄而减少;在ApoE-/-小鼠主动脉壁和斑块内PPARγ表达随AS病变进程而增加。推测ApoE-/-小鼠主动脉斑块PPARγ表达上调可能是机体一种代偿行为和自我保护机制。     

植物甾醇酯对大鼠主动脉衰老及相关基因表达的影响

目的:探讨植物甾醇酯延缓大鼠主动脉衰老的作用及其机制。方法:将42只12月龄雌性SD大鼠随机均分为对照组、模型组和植物甾醇酯干预组,分别喂食基础饲料、高脂饲料和高脂加2%植物甾醇酯(W/W)饲料6个月。采用HE染色法和Masson染色法对主动脉横截面石蜡切片进行染色,观察主动脉组织的病理学改变,对血管壁平滑肌细胞和胶原纤维的绝对面积进行图像分析。检测血浆脂质蛋白、晚期糖基化终末产物(AGEs)、丙二醛(MDA)的含量以及超氧化物歧化酶(SOD)、过氧化氢酶(CAT)的活性。分别采用real-time PCR和Western blot的方法评估主动脉组织沉默信息调节因子1(SIRT1)和过氧化物酶体增殖物激活受体γ(PPARγ)的mRNA和蛋白表达水平。结果:与模型组相比,植物甾醇酯干预组的血浆总胆固醇和低密度脂蛋白胆固醇水平显著降低,高密度脂蛋白胆固醇的水平相反(P0.05),甘油三酯的水平没有统计学差异;主动脉内膜和中膜的增厚以及平滑肌细胞的迁移均得到改善;主动脉平滑肌细胞和胶原纤维的含量显著下降(P0.05);血浆AGEs的含量显著降低(P0.05);机体的抗氧化功能有所提升,血浆MDA的含量显著减少(P0.05),SOD和CAT活性的差异没有统计学意义;PPARγ的表达下调,SIRT1的表达上调(P0.05)。结论:植物甾醇酯能够延缓大鼠主动脉的衰老。其机制可能与降低机体活性氧的生成有关。植物甾醇酯可能通过激活SIRT1或抑制PPARγ的表达而发挥作用。     

成人下腹壁厚度测量及其对根据指南针原理设计的排尿报警装置的意义

目的　了解正常成人下腹壁厚度,并探讨其相关因素及其对根据指南针原理设计的排尿报警装置的意义。 方法　应用B超连续测量l00例成人的下腹壁及其浅层和深层的厚度,膀胱的前后径、上下径及左右径,并测量身高、体质量、测量点到脐部的距离,计算体质量指数（BMI）和膀胱容量,分析影响下腹壁厚度的相关因素。 结果　本组成人的下腹壁厚度(23.4±6.6)mm,95%可信区间为22.1～24.7　mm,与下腹壁深层厚度、浅层厚度和BMI、体质量、测量点到脐部的距离呈正相关(P<0.05),与膀胱容量、膀胱的上下径和左右径呈负相关(P<0.05),而与性别、身高、年龄、膀胱的前后径无相关性(P>0.05)。 结论　应用超声测量的成人下腹壁厚度为(23.4±6.6)mm,营养状态是最重要的影响因素,这为根据指南针原理设计的排尿报警装置的可行性提供了新的证据,对该装置的进一步研究具有重要的参考意义。     

Hypertension,social rank,and aortic arteriosclerosis in CBA/J mice

A significant rise in systolic blood pressure and increased aortic arteriosclerosis was observed over a period of four months in dominant male mice as compared to subordinate and control animals. Subordinate animals assuming the dominant position also developed a significant rise in blood pressure and dominant animals removed from social interaction showed a significant decrease in blood pressure. Males that were castrated failed to develop a social hierarchy and exhibited normotensive blood pressure. Also dominant animals exhibited higher plasma testosterone levels and more aortic arteriosclerosis than subordinates.     

Prevalence of pannus formation after aortic valve replacement: clinical aspects and surgical management

Pannus formation after aortic valve replacement is not common, but obstruction due to chronic pannus is one of the most serious complications of valve replacement. The causes of pannus formation are still unknown and effective preventive methods have not been fully elucidated. We reviewed our clinical experience of all patients who underwent reoperation for prosthetic aortic valve obstruction due to pannus formation between 1973 and 2004. We compared the initial 18-year period of surgery, when the Björk–Shiley tilting-disk valve was used, and the subsequent 13-year period of surgery, when the St. Jude Medical valve was used. Seven of a total of 390 patients (1.8%) required reoperation for prosthetic aortic valve obstruction due to pannus formation. All seven patients were women; four patients underwent resection of the pannus and three patients needed replacement of the valve. The frequency of pannus formation in the early group was 2.4% (6/253), whereas it was 0.73% (1/137) in the late group (P < 0.05). Pannus was localized at the minor orifice of the Björk–Shiley valve in the early group and turbulent transvalvular blood flow was considered to be one of the important factors triggering its growth. We also consider that small bileaflet valves have the possibility of promoting pannus formation and that the implantation of a larger prosthesis can contribute to reducing the occurrence of pannus.     

基质金属蛋白酶及其抑制剂在腹主动脉瘤发病中的作用

随着现代医学的发展 ,腹主动脉瘤 (ａｂｄｏｍｉｎａｌａｏｒｔｉｃａｎｅｕｒｙｓｍｓ ,ＡＡＡ)在临床上已得到有效治疗 ,但本病的促发因素以及持续扩张以致破裂的控制因素仍存在较大的争议 ,经过免疫、遗传、分子生物学及血流动力学等方面的广泛研究 ,所有学者均认为腹主动脉壁的基质降解是ＡＡＡ形成和发展的关键环节 ,基质金属蛋白酶 (ｍａｔｒｉｘｍｅｔａｌｌｏｐｒｏｔｅｉｎａｓｅ ,ＭＭＰ)是破坏细胞外基质 (ｅｘｔｒａｃｅｌｌｕｌａｒｍａｔｒｉｘ ,ＥＣＭ )中最主要一类酶系 ,本文就ＭＭＰ及其抑制剂类别功能、来源与表达以及两…     

Right-Sided Aorta: A cadaver report and brief discussion of human aortic arch anomalies

We observed an unusual right-sided aorta during routine laboratory dissection. The short aortic arch passed to the right side of the esophagus and trachea and had four branches, from proximal to distal: left common carotid, right common carotid, right subclavian, left subclavian arteries. The ligamentum arteriosum connected the pulmonary trunk to the left subclavian artery and lay to the left of the esophagus and trachea. The left recurrent laryngeal nerve passed under the ligamentum arteriosum while the right recurrent laryngeal nerve passed under the aortic arch. The descending thoracic aorta was situated near the midline, anterior to the vertebral bodies; consequently, the right posterior intercostal arteries were shorter than normal. The large veins of the thorax and the other thoracic organs appeared normal.