Understanding capture detection.

Automatic capture detection systems are currently available in several cardiac pacing devices. All current systems use low-polarization electrodes and no beat to beat detection system is available for all types of electrodes. In addition the success ratio for currently available systems is not always 100%. Failure to detect capture reliably is often related to the behaviour of the electrode-tissue interface under different circumstances. Pacemaker electrodes can be considered electrochemical cells with complicated characteristics depending on time, temperature and electrical charge. This electrochemical cell is disturbed when a charge is transferred across the electrode-tissue interface during pacing. Several measures can be taken in order to minimise this disturbance or pace polarization artefact (PPA) including the use of high active surface area electrodes and application of tri-phasic pacing pulses. Another factor influencing detection of evoked potentials is the input circuit of the pacemaker affecting the PPA and the evoked response. Positive PPAs can be falsely interpreted as evoked potentials due to the undershoot of the second order filters applied in modern cardiac pacemakers. This paper explains the behaviour of the interface between the electrode and the cardiac tissue in combination with the pacemaker output circuits and input amplifiers under different circumstances.     

Relationship Among MRTA, DXA, and QUS

Dual-energy X-ray absorptiometry (DXA) and quantitative ultrasound (QUS) are the accepted modalities for the evaluation of fracture risk in the clinical setting. However, neither method provides a direct measurement of bone mechanics. In this study, we investigated a prototype device, known as a mechanical response tissue analyzer (MRTA), which provides direct mechanical measurements of mechanical properties of bone. A total of 56 healthy volunteers (20 men and 36 women) between the ages of 18 and 83 were recruited. The MRTA was used to measure the cross-sectional bending stiffness (EI) of the ulna bone. Axial speed of sound (SOS) at the ulna bone was determined by QUS; bone mineral content (BMC) and bone mineral density (BMD) were determined by DXA. Correlations, regression analysis, and analyses of variance (ANOVAs) were used to compare the three modalities. These analyses revealed that although there are strong linear relationships among the data collected by the various technologies, the bone properties reflected by MRTA are not fully explained by DXA and QUS. We conclude that the total information conveyed by MRTA measurements is unique. Further research is needed to delineate the different qualities of bone strength that are captured by MRTA, but not by DXA or QUS.     

Local inflammatory response in choriodecidua induced by Ureaplasma urealyticum

Ureaplasma urealyticum is the bacterial species most often connected with preterm birth, although it often colonises the amniotic fluid without any adverse effects. The induction of preterm labour seems to depend on whether the bacteria produce an inflammatory reaction. In vitro stimulation of choriodecidual tissue with high amounts of U. urealyticum or with lipopolysaccharide induced a qualitatively similar inflammatory response detected by the production of tumour necrosis factor alpha, followed by secretion of anti-inflammatory cytokine interleukin-10 and of prostaglandin E₂. Lower quantities of bacteria failed to induce any response.     

Singularities explained: Response to Klein.

Klein [Klein, A. S. (2006). Separating transducer nonlinearities and multiplicative noise in contrast discrimination. Vision Research, 46, 4279-4293] questions the existence of intrinsic singularities in two-alternative force-choice (2AFC) Signal Detection Theory (SDT) models, suggesting that the singularities found in Katkov et al. [Katkov, M., Tsodyks, M., & Sagi, D. (2006a). Singularities in the inverse modeling of 2AFC contrast discrimination data. Vision Research, 46, 259-266; Katkov, M., Tsodyks, M., & Sagi, D. (2006b). Analysis of two-alternative force-choice Signal Detection Theory model. Journal of Mathematical Psychology, 50, 411-420] are due to discarding higher order terms in the Taylor expansion of d' and/or limited to steep psychometric functions. Here we provide some simple intuitive examples that illustrate the results described in Katkov et al. (2006a, 2006b). We show, for the constant noise model, that singularities exist when exact values of d' are computed and that the singularities are not limited to steep psychometric functions. In these cases the disambiguation of the different models requires millions of trials.     

论现阶段医疗保险个人帐户存在的必要性

[目的]探讨医疗保险个人账户是否有存在的必要性。[方法]将方案设计的初衷与实际运行相比较分析。[结果]医疗保险个人帐户约束和积累作用发挥得不理想，在一定程度上抑制了老年人和陵性病患者的医疗需要。从我国国民的心理承受力和国民素质及解决人口老龄化时支付危机等方面的考虑，笔者认为在现阶段有其存在的必要。[结论]应采取扩大覆盖对象，调整使用范围，取消退休人员个人账户，加强对供方的管理以及其它配套措施来进一步完善。     

Limbus-based versus Fornix-based conjunctival flap in filtering surgery

Summary A randomized prospective study was performed to compare the results of filtering surgery using a Limbusbased versus a Fornix-based conjunctival flap. The wound closure of the Fornix-based flap was performed using a running 10/0 nylon suture at the limbus. No statistical significant difference of IOP regulation was found between the two groups. There was a tendency of reduced occurrence of shallow anterior chamber and of less vascularized filtering blebs in the Fornix-based technique.     

Addition of sufentanil to bupivacaine in caudal block effect on stress responses in children

BACKGROUND: The aim of the present randomized study was to determine the effect of adding sufentanil to bupivacaine, compared with bupivacaine alone in caudal block, on the surgical stress response in children. METHODS: The children were premedicated with midazolam 0.5 mg/kg. All children received induction with nitrous oxide and sevoflurane. Anesthesia was maintained with the same volatile agents in the both groups. The children were randomly allocated to two groups. Group I received bupivacaine alone (n = 17) and group II received bupivacaine + sufentanil (n = 16). Caudal block was performed with 0.25% bupivacaine 2 mg/kg (group I) or 0.25% bupivacaine 2 mg/kg with sufentanil 0.5 microg/kg (group II) after induction of anesthesia. Blood samples were obtained after induction of anesthesia (T(0)) to measure baseline concentrations of cortisol, prolactin, glucose and insulin. Additional samples were obtained 30 min after the start of surgery (T(1)), and 60 min after the end of surgery (T(2)). RESULTS: All of the basal values (T(0)) were within the normal ranges of the authors' laboratory for children of this age group and there were no differences between the groups (P > 0.05). In both groups, glucose concentration increased at T(1), compared with T(0) and T(2) (P < 0.05). The glucose concentration was unchanged at T(2) compared with T(0) in both group (P > 0.05). In both groups, prolactin concentration increased at T(1), compared with T(0) and decreased at T(2), compared with T(1) (P < 0.05). Cortisol decreased at T(1) and T(2), compared with T(0) in both groups. (P < 0.05). Insulin concentration remained unchanged at T(0) and T(2), but increased slightly at T(1) in both groups (P > 0.05). There were no significant differences in plasma prolactin, cortisol, glucose and insulin levels between the two groups at T(1) and T(2) (P > 0.05). CONCLUSION: There is no advantage in adding 0.5 microg/kg sufentanil to bupivacaine over bupivacaine alone in the caudal block, with regard to the surgical stress response in children.     

超声造影在肝癌介入治疗后疗效评价中的应用

目的:探讨实时灰阶超声造影(contrast-enhanced grey-scale ultrasonography,CE-US)在肝癌介入治疗后疗效评价中的应用价值。方法:经肘前浅静脉团注超声对比剂SonoVue,观察各时相病灶的强化特点,并与治疗前CE-US、治疗后CT、MRI图像及随访结果进行比较,综合判断介入治疗效果。结果:CE-US可以清晰地显示病灶内有无局部或整体强化,能准确评价肝癌介入治疗后疗效。结论:CE-US在评价肝癌介入疗效时具有重要的临床价值。