Post-resuscitation hemodynamics and relationship to the duration of ventricular fibrillation

OBJECTIVE: We have observed consistent hemodynamic patterns after restoration of spontaneous circulation (ROSC) after ventricular fibrillation (VF) cardiac arrest. We sought to characterize the time-course of these patterns, and to determine whether these differed based on duration of the VF insult. METHODS: We performed a retrospective review of data from a randomized animal experiment that was conducted in an AAALAC-approved animal laboratory. We used mixed-breed domestic swine of either sex. Animals were anesthetized and instrumented for continuous recording of ECG and blood pressures. VF was induced electrically and allowed to progress for various times ranging from brief (22s) to moderate (less than 3min) to prolonged (3-10min). All animals were initially shocked (150J) up to three times. If ROSC was not achieved on the three initial shocks, a standardized treatment protocol was followed. We defined cardiovascular collapse as a SBP<90mmHg sustained for 1min. For statistical purposes, we classified animals as having VF of <3min, or >3min duration. Data were analyzed with Fisher's exact test and survival analysis. RESULTS: A hyperdynamic phase, consisting of very high-blood pressures and tachycardia, was seen in all animals immediately after ROSC. This lasts from 1 to 4min. Post-resuscitation cardiovascular collapse occurred in 2/7 (29%) animals in the <3min group and 13/14 in the >3min group (93%) p=0.006. Onset of cardiovascular collapse was highly related to duration of VF (log-rank p=0.004). CONCLUSIONS: There are two distinct phases of hemodynamic change after resuscitation of VF. The first phase is a brief hyperdynamic phase. The second phase is either stabilization or cardiovascular collapse. When VF is brief, blood pressures often return to normal without exogenous support. When VF was prolonged animals were rescued with exogenous pressor. Healthcare providers should be prepared to provide pressor support for patients having ROSC after prolonged VF.     

Corticotomy facilitated orthodontics: Review of a technique

Corticotomy found to be effective in accelerating orthodontic treatment. The most important factors in the success of this technique is proper case selection and careful surgical and orthodontic treatment.Corticotomy facilitated orthodontics advocated for comprehensive fixed orthodontic appliances in conjunction with full thickness flaps and labial and lingual corticotomies around teeth to be moved. Bone graft should be applied directly over the bone cuts and the flap sutured in place. Tooth movement should be initiated two weeks after the surgery, and every two weeks thereafter by activation of the orthodontic appliance.Orthodontic treatment time with this technique will be reduced to one-third the time of conventional orthodontics. Alveolar augmentation of labial and lingual cortical plates were used in an effort to enhance and strengthen the periodontium, reasoning that the addition of bone to alveolar housing of the teeth, using modern bone grafting techniques, ensures root coverage as the dental arch expanded.Corticotomy facilitated orthodontics is promising procedure but only few cases were reported in the literature. Controlled clinical and histological studies are needed to understand the biology of tooth movement with this procedure, the effect on teeth and bone, post-retention stability, measuring the volume of mature bone formation, and determining the status of the periodontium and roots after treatment.     

Echocardiographic "Eyewitness" of Aortic Valve Vegetation Detachment

Embolic phenomena are associated with endocarditis. We report a patient suffering from infective endocarditis, in which the exact moment of detachment of an aortic valve vegetation and subsequent embolization was eyewitnessed during two-dimensional echocardiography, and the entire episode was recorded on video tape.     

Influence of Indeloxazine Hydrochloride upon Photic Driving Responses Elicited by Flickering Dot Pattern and Red Flicker Stimuli in Elderly Patients

Abstract: We studied the influence of indeloxazine hydrochloride (IH) upon photic driving responses (PDRs) elicited by a 5 Hz flickering dot pattern and red flicker stimuli. Comparisons were made from a total of 22 elderly patients. By oral IH administration, clinical improvement was found in 12 patients with cerebral arteriosclerosis (improved group), whereas it was not observed in 6 patients with cerebral arteriosclerosis, 2 patients with multiinfarct dementia and 2 patients with Alzheimer's disease (unimproved group). Before and after the IH administration, an EEG examination by the above visual stimuli was carried out in each patient; a power spectral analysis of the occipital PDRs elicited by the visual stimuli was then made. The powers of PDRs elicited by the flickering dot pattern stimulation were not significantly different in both groups; those of 10 and 15 Hz PDRs elicited by the red flicker stimulation, however, decreased significantly by the IH administration in the improved group. It was suggested that such an analysis of PDRs elicited by the red flicker stimulation might perhaps be useful as one of the indicators to evaluate the efficacy of IH.     

抑制糜酶活性对动脉粥样硬化早期仓鼠腹主动脉血流动力学的影响

目的 探讨抑制糜酶活性对仓鼠动脉粥样硬化病变腹主动脉血流动力学的影响。方法 42只8周龄雄性叙利亚金黄仓鼠随机分为A、B、C三组，各14只。A组为高脂对照组，B组采用高脂喂养＋曲尼司特灌胃，C组为正常对照组。分别在第0周和第12周末进行血脂检测，并应用多普勒超声检测各组仓鼠腹主动脉收缩期峰值血流速度（SV）、舒张末期血流速度（DV）、平均血流速度（MV）、搏动指数（PI）和阻力指数（RI）。第12周末处死仓鼠，采用体外灌流技术检测腹主动脉的糜酶活性及血管紧张素转换酶（ACE）活性。结果 12周后，A、B两组与C组比较，总胆固醇、甘油三酯、低密度脂蛋白均显著增高（P〈0.01）。多普勒超声检测显示，B组较A组SV、MV、PI和RI显著降低（P〈0．01），DV显著增高（P〈0．05）。A、B两组腹主动脉糜酶活性均较C组显著增高（分别升高63％、20％，P〈0．01），B组糜酶活性与A组比较显著降低26％（P〈0．01），ACE活性轻度增高，但组间比较差异无统计学意义（P〉（0．05）。糜酶活性与血流动力学指标SV、PI和RI呈正相关（r分别为0．47、0．60和0．61，P〈0．01）。结论 抑制糜酶活性可显著改善仓鼠动脉粥样硬化病变腹主动脉的血流动力学水平，进而延缓动脉粥样硬化病变的发展。     

Human jaw joint hypermobility: Diagnosis and biomechanical modelling

Patients with hypermobility disorders of the jaw joint experience joint sounds and jerky movements of the jaw. In severe cases, a subluxation or luxation can occur. Clinically, hypermobility disorders should be differentiated from disc displacements. With biomechanical modelling, we previously identified the anterior slope angle of the eminence and the orientation of the jaw closers to potentially contribute to hypermobility disorders. Using cone‐beam computed tomography (CBCT), we constructed patient‐specific models of the masticatory system to incorporate these aspects. It is not known whether the clinical diagnosis of hypermobility disorders is associated with the prediction of hypermobility by a patient‐specific biomechanical model. Fifteen patients and eleven controls, matched for gender and age, were enrolled in the study. Clinical diagnosis was performed according to the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) and additional testing to differentiate hypermobility from disc displacements. Forward simulations with patient‐specific biomechanical models were performed for maximum opening and subsequent closing of the jaw. This predicted a hypermobility disorder (luxation) or a control (normal closing). We found no association between the clinical diagnosis and predictions of hypermobility disorders. The biomechanical models overestimated the number of patients, yielding a low specificity. The role of the collagenous structures remains unclear; therefore, the articular disc and the ligaments should be modelled in greater detail. This also holds for the fanned shape of the temporalis muscle. However, for the osseous structures, we determined post hoc that the anterior slope angle of the articular eminence is steeper in patients than in controls.     

嗜铬细胞瘤围手术期血压变化的影响因素分析

目的 分析引起嗜铬细胞瘤围手术期血压波动的影响因素,探讨改善其血流动力学的措施.方法 对2000-2010年收治的经手术治疗的嗜铬细胞瘤患者的临床资料进行回顾性研究.采用Pearson相关分析和多元Logistic回归等统计学方法对影响围手术期血压波动的因素进行分析.结果 Pearson相关分析显示术中收缩压的最大波动值(△SBP)的影响因素包括术前最高收缩压(r=0.196,P=0.013)、术前24h尿肾上腺素含量(r=0.207,P=0.008)及术中失血量(r=0.253,P=0.003).多元Logistic回归分析显示影响术后顽固性低血压的因素包括24h尿去甲肾上腺素(OR=1.273,P=0.002)、术前准备时间(OR=0.921,P=0.034);术后高血压的危险因素有肿瘤残留(OR=16.920,P=0.001)、术前红细胞压积变化(OR=1.467,P=0.018).结论 尽管经过充分的术前准备,嗜铬细胞瘤患者围手术期仍可发生较大的血压波动.嗜铬细胞瘤围手术期的血压波动受到多种因素影响,针对这些影响因素采取措施,可减少血压的波动,从而减少手术风险.     

Pattern formation and polarity sorting of driven actin filaments on lipid membranes

Collective motion of active matter is ubiquitously observed, ranging from propelled colloids to flocks of bird, and often features the formation of complex structures composed of agents moving coherently. However, it remains extremely challenging to predict emergent patterns from the binary interaction between agents, especially as only a limited number of interaction regimes have been experimentally observed so far. Here, we introduce an actin gliding assay coupled to a supported lipid bilayer, whose fluidity forces the interaction between self-propelled filaments to be dominated by steric repulsion. This results in filaments stopping upon binary collisions and eventually aligning nematically. Such a binary interaction rule results at high densities in the emergence of dynamic collectively moving structures including clusters, vortices, and streams of filaments. Despite the microscopic interaction having a nematic symmetry, the emergent structures are found to be polar, with filaments collectively moving in the same direction. This is due to polar biases introduced by the stopping upon collision, both on the individual filaments scale as well as on the scale of collective structures. In this context, positive half-charged topological defects turn out to be a most efficient trapping and polarity sorting conformation.

Collective motion of active matter is ubiquitous, with observations ranging from flocks of birds (1) and schools of fish (2) to propelled colloids (3). The interactions between agents in such systems lead to the formation of complex structures including clusters, swirls, or lanes of agents moving coherently (4). The structure of the emerging patterns strongly depends on both the agents’ shape and their velocity alignment mechanism. A particular case is that of elongated microscopic particles that translate along their major axis in a quasi-two-dimensional environment and only interact upon collision (5, 6). In the context of cytoskeletal systems, gliding actin filaments or microtubules propelled by molecular motors are found to be able to readily crawl over each other and only retain a weak level of alignment upon binary collisions, which eventually leads at high densities to a diverse set of patterns (7). Such resulting patterns are found to be strongly dependent on this weak microscopic alignment interaction, and therefore, even slightly tuning it causes the system to switch between polar and nematic phases, separated by a coexistence regime (8, 9). Observed structures in cytoskeletal systems with weak to moderate interactions include nematic lanes, polar waves, and vortices (10–12). Conversely, pattern formation in systems of elongated bacteria or granular matter is often based on hard interactions with a strong steric component (13–18). In this repulsion-dominated regime, particles are unable to crawl over each other and must stop upon collision. In the limiting case of spherical self-propelled particles, this kind of steric interaction can lead to a stable phase separation between stuck and moving particles, the so-called motility induced phase separation (MIPS) (19). On the other hand, in the case of elongated particles, steric effects can still act as velocity aligning mechanisms. As orientation mismatches are unstable, particles end up aligning and this leads to flocking behavior rather than to phase separation (5, 20–25). This latter case, in which strong steric constraints dominate binary interactions but alignment is still present, is poorly understood, and how modeling has to be extended to account for the emergent collective behavior of elongated, flexible agents with volume exclusion also remains still under debate (26–30). This is partly due to the lack of microscopic experimental systems allowing to explore this regime. Semiflexible cytoskeletal filaments would be the best candidate, but their volume exclusion is usually too weak. However, having them propelled by motors immobilized on a fluid membrane would be a promising route to bridge this experimental gap (31).Here, we enforce a steric repulsion-dominated interaction, leading to alignment between actin filaments by coupling myosin motors to a fluid-supported lipid bilayer. Because of the slippage of the motors on the membrane, the force propelling the filaments is too weak to enable filaments to crawl over each other and thus effectively implements a repulsion-dominated regime, with filaments stopping upon collisions. Eventually, however, because of the thermal fluctuations of their tips, filaments can align and resume motion. The experimental realization of such a microscopic binary interaction, based on volume exclusion, enables us to observe and quantify the resulting pattern formation process in a system of active semiflexible filaments. We then first characterize the interaction at the single filament scale, showing that it leads to nematic alignment. As the filaments’ density is increased, patterns of collective motion emerge, ranging from clusters to thick streams and vortices. Despite the nematic collision rule, we find the emerging structures to be locally polar. The repulsion-dominated interaction indeed introduces a polar bias not only due to the tendency of active filaments or clusters to keep moving together after a polar collision but also by forcing filaments with similar orientation to stop and accumulate when encountering an obstacle. In particular, at high densities, such an interaction leads to the formation of transient local +1/2 topological defects, which act as wedges and, therefore, effectively trap and polarity-sort motile filaments. We interpret this trapping mechanism as an analog of MIPS for elongated self-propelled particles.     

Immediate Efficacy of Laterally Wedged Insoles With Arch Support on Walking in Persons With Bilateral Medial Knee Osteoarthritis

ObjectiveTo investigate the immediate efficacy of laterally wedged insoles with arch support (LWAS) on gait in persons with bilateral medial knee osteoarthritis (OA).DesignA prospective case-control intervention study.SettingA gait laboratory with a 6-camera motion analysis system and 2 forceplates.ParticipantsFifteen women with bilateral medial knee OA and 15 healthy control subjects (N=30).InterventionsLWAS.Main Outcome MeasuresSubjective knee pain and objective biomechanical indices, namely, joint angles and moments in the frontal plane, frontal plane ground reaction force and lever arm, as well as medial/lateral center of mass and center of pressure during gait.ResultsWhen wearing the LWAS, knee pain during gait in persons with medial knee OA decreased (P=.01). Peak internal knee abductor moments were also reduced (P<.001) with increasing foot progression angles, laterally shifted center of pressure, and a shortened frontal plane lever arm (all P<.05). However, ankle invertor moments were increased (P<.05) when wearing the LWAS.ConclusionsAlthough peak internal knee abductor moment and knee pain were immediately reduced during gait when wearing the LWAS, increased ankle invertor moments were found, suggesting that the LWAS should be used with caution. Strengthening and monitoring the condition of the ankle invertor muscles may be necessary if the LWAS is used as an intervention for persons with bilateral medial knee OA.     

妊娠高血压患者肾血流动力学与血管内皮功能的相关性研究

目的 探讨妊娠高血压疾病(HDCP)患者内皮素-1(ET-1)和一氧化氮(NO)对肾动脉血流动力学的影响及肾血流动力学改变在妊娠高血压诊断中的应用价值.方法 妊娠高血压患者56例,其中妊娠期高血压组(GH)18例,轻度子痫前期组(轻度PE) 18例,重度子痫前期组(重度PE)20例;正常妊娠者20例为对照组.应用彩色多普勒超声测量肾叶间动脉收缩期峰值流速(PSV)、舒张末期流速(EDV)、阻力指数(RI)、搏动指数(PI)等指标,同时检测血清ET-1和NO浓度.结果 轻度及重度PE组EDV低于正常妊娠组,差异有统计学意义(P＜0.05).轻度及重度PE组RI、PI、S/D值均高于正常妊娠组,差异有统计学意义(P＜0.05).妊娠高血压疾病患者血清ET-1水平高于正常妊娠组,且随病情的加重ET-1水平升高,差异有统计学意义(P＜0.01);妊娠高血压患者血清NO水平低于正常妊娠组,且随病情的加重NO水平降低,差异有统计学意义(P＜0.01).妊娠高血压疾病患者肾叶间动脉S/D、RI、PI与血清ET-1呈正相关(P＜0.05),与血清NO呈负相关(P＜0.01).结论 彩色多普勒超声测量的肾血流动力学参数是反映HDCP患者血流变化和肾脏损害的敏感指标,与反映血管内皮功能的细胞因子ET-1和NO有良好的相关性.