Effect of artifacts due to flowing blood on the reproducibility of phase-contrast measurements of myocardial motion

The reproducibility of myocardial motion trajectories calculated from cine phase-contrast (PC) velocity data is reduced by artifacts due to the inconsistent motion of intracardiac blood. Spatial presaturation reduces these artifacts but requires a longer sequence TR, with a potentially negative effect on trajectory accuracy and reproducibility. We investigated the effect of spatial presaturation on trajectory reproducibility. A midventricular transaxial slice was imaged in five normal volunteers. The same slice was imaged three times each with sequences using spatial presaturation or not. Because the most serious artifacts originate in the heart chambers and propagate in the phase-encoded direction, myocardial regions that were in line with the heart chambers (in the phase-encode direction) had the highest artifact level in the scans without spatial presaturation. The reproducibility of trajectories for regions placed in these areas (the anterior wall, septum and posterior wall in the transaxial scans with phase encoding in the anterior-posterior direction) improved by a factor of two when presaturation was used (P < .001). In areas that were not in line with the heart chambers (eg, the anterior aspect of the lateral wall in the transaxial scans), the effect of presaturation was not significant. These results correlate well with the measured reduction in artifact level. The reproducibility of myocardial motion trajectories over large areas of the heart is improved to approximately 1 mm when presaturation is used. Therefore, use of presaturation is recommended for myocardial motion studies using cine PC velocity data.     

牛磺酸对高血压和血管活性物质的影响

在原发性高血压(EH)患者、大鼠腹主动脉狭窄和高盐摄入引起高血压模型上,观察到口服牛磺酸治疗4周后均明显降低平均动脉压和收缩压,42.2%的患者血压恢复正常,并能抑制EH患者和高血压大鼠血浆内皮素(ET)、血管紧张素II(AII)水平的升高,增加高血压大鼠血浆降钙素基因相关肽(CGRP)和主动脉组织中的牛磺酸含量.以上结果表明,牛磺酸在降压作用同时伴有缩血管物质的降低和舒血管物质的增加,为以牛磺酸作为降血压辅助药物提供了依据.     

Initial experience with dynamic MR imaging in evaluation of normal bone marrow versus malignant bone marrow infiltrations in humans

The purpose of this study was (a) evaluation of dynamic contrast-enhanced MR imaging of normal bone marrow versus malignant bone marrow infiltrations in patients with proven B-cell-type chronic lymphocytic leukemia (B-CLL) and (b) correlation with the clinical stage according to Binet (stages A, B, C) and response to therapy. Bone marrow imaging of the lumbar spine, pelvis, and proximal femurs was performed at 1.5 T in 45 patients without known malignancy and in 30 patients with B-CLL. The differences between opposed-phase and in-phase dynamic gradient-echo sequences before and up to 10 minutes after intravenous application of .1 mmol/kg body weight of gadolinium-diethylenetriamine penta-acetic acid (Gd-DTPA) were evaluated in normal bone marrow. The contrast-enhancement patterns of normal and malignant bone marrow were compared using the opposed-phase dynamic gradient-echo sequence. Ten of the patients with bone marrow infiltrations (Binet stage C) additionally underwent MR imaging follow-up during therapy. Opposed-phase gradient echo sequences demonstrated a signal decrease of normal bone marrow, and in-phase gradient echo sequences demonstrated a signal increase of normal bone marrow after administration of Gd-DTPA. The dynamic signal intensity time courses differed significantly (P < .05) between Binet stages B and C and controls as well as among the three Binet stages of B-CLL. In the 10 patients followed during therapy, MR imaging sensitively demonstrated response (n = 6), nonresponse (n = 2), or relapse after initial response (n = 2). In out-of-phase imaging, both normal bone marrow and initial bone marrow infiltration in CLL stage Binet A show signal decrease after administration of contrast agent, whereas there is increase in signal intensity in higher-grade bone marrow infiltration in Binet stage B or C disease. The signal loss of normal bone marrow in out-of-phase imaging is a phase effect rather than a T2* effect. The differentiation of initial from higher-grade bone marrow infiltration on out-of-phase images relies solely on a shift in the fat/water ratio.     

体外培养新生大鼠心房壁中的CGRP-IR和NPY-IR神经细胞

对体外培养新生SD大鼠心房壁的神经细胞，按SternbergerPAP法进行了降钙素基因相关肽（CGRP）和神经肽Y（NPY）免疫细胞化学研究。结果显示：CGRP-IR阳性细胞数量较少，实验的5份标本只有2份见到阳性细胞，而NPY-IR阳性细胞在所有实验标本中均可见到。本研究在培养条件下证实心内神经节中有CGRP-IR阳性细胞存在，支持心脏有器官内感觉神经细胞的设想。同时对心内神经细胞的化学性质进行了讨论。     

Prostaglandins and CGRP release from cardiac sensory nerves

Summary (1) The possible influence of Prostaglandins (PG) E₁ and I₂ as well as ischaemia, ouabain and bradykinin on the outflow of calcitonin gene-related peptide (CGRP)- and neuropeptide Y (NPY)-like immunoreactivity (LI) from the guinea-pig heart was studied in vitro. (2) Exposure to PGE₁ (10^–5 M), but not PGI₂ (10^–5 M), induced an increased outflow, suggesting release of CGRP-LI. PGE₁ simultaneously increased the contractile force and heart rate while no effects were observed on perfusate volume or outflow of NPY-LI. PGI₂ had no effect on contractile parameters or coronary flow. In separate experiments on capsaicin-pretreated animals, the stimulatory effects of PGE₁ on heart rate and contractile force remained unchanged while no increased CGRP-LI outflow was detectable. (3) Ouabain, bradykinin and reperfusion after total stop-flow ischaemia was associated with an indomethacin-resistant increase in perfusate levels of CGRP-LI but not of NPY-LI. While ouabain markedly increased the contractile force, exposure to bradykinin or ischaemia did not induce any clear-cut changes in contractile force or heart rate. (4) Capsaicin-exposure evoked a markedly increased outflow of CGRP-LI but not of NPY-LI in combination with an increase in heart rate and a decrease in contractile force. Repeated administration of capsaicin induced tachyphylaxis. The stimulatory effects of capsaicin on CGRP-LI outflow and heart rate, but not the negative inotropic effect, did not occur in capsaicin-pretreated animals. (5) It is concluded that PGE₁, but not PGI₂, can activate cardiac capsaicin-sensitive fibres as revealed by increased outflow of CGRP-LI. The cardiostimulatory effects induced by PGE₁ are not related to CGRP release, however. A possible prostaglandin link in the CGRP-LI released by ouabain, bradykinin or ischaemia seems unlikely. Send offprint requests to: A. Franco-Cereceda at the above address     

Early nerve regeneration after Achilles tendon rupture — a prerequisite for healing? A study in the rat

Nerve regeneration during healing of Achilles tendon rupture in the rat was studied by immunohistochemistry including semi-quantitative assessment. Neuronal markers for regenerating and mature fibers, ie., growth associated protein 43 (GAP-43) and protein gene product 9.5 (PGP 9.5), respectively, were analyzed at different time points (1-16 weeks) post-rupture. In the paratenon, both the ruptured and intact contralateral tendon (control) consistently exhibited immunoreactivity to the two neuronal markers. However, in the proper tendinous tissue only the ruptured tendon showed immunoreactivity to GAP-43 and PGP 9.5. This expression was seen already at week 1 post-rupture to reach a peak at week 6 followed by a successive drop till week 16. Also the occurrence of sensory and autonomic fibers according to immunoreactivity for calcitonin gene-related peptide (CGRP) and neuropeptide Y (NPY), respectively, was analyzed. CGRP-positivity was abundantly seen from weeks 2-6 in both perivascular and sprouting free nerve endings in the proper tendon tissue undergoing healing. NPY appeared later, at weeks 6-8 post-rupture around blood vessels mainly located in the surrounding loose connective tissue. Apart from a role in vasoaction (CGRP, vasodilatory; NPY, vasoconstrictory). both neuropeptides have been implicated in fibroblast and endothelial cell proliferation required for angiogenesis. The present study shows that early healing of ruptured tendons is characterized by an orchestrated, temporal appearance of nerve fibers expressing peptides with different actions. The observed pattern of neuronal regeneration and neuropeptide expression may prove to be important for normal connective tissue healing.     

脂多糖处理人皮肤成纤维细胞培养上清液对肝脏急性期反应物的诱导

目的:观察皮肤成纤维细胞在某些条件下释放的细胞因子对肝细胞急性期反应的影响。方法：用细菌脂多糖孵育人的皮肤成纤维细胞，测定培养液中IL－1β和IL－6浓度；并用不同浓度和组合的细胞培养液、重组IL－6（rhIL－6）和地塞米松孵育鼠肝瘤H4细胞，观察白蛋白、α1酸糖蛋白、α1抗胰蛋白酶和转铁蛋白mRNA表达的变化。结果：发现细菌脂多糖刺激成纤维细胞合成IL－6，而地塞米松抑制这一作用。IL－6和细菌脂多糖孵育的成纤维细胞培养液抑制白蛋白mRNA的表达，成纤维细胞培养液。地塞米松促进α1酸糖蛋白、α1抗胰蛋白酶mRNA的表达、单用IL－6即能抑制白蛋白和转铁蛋白mRNA的表达，地塞米松加强IL－6和成纤维细胞培养液的抑制作用。结论：（1）细菌脂多糖处理的成纤维细胞能够分泌IL－6，但不分泌11－1β；（2）成纤维细胞产生的细胞因子能够调节急性期反应时的肝脏蛋白合成；（3）地塞米松抑制成纤维细胞产生IL－6，但加强其刺激急性期反应的能力。     

全腔静脉肺动脉连接手术前后血浆心钠素含量变化及其临床意义

目的　探讨全腔静脉肺动脉连接手术 (TCPC)前后心钠素 (ANP)的变化情况及其临床意义。方法　观察组为 18例全腔静脉肺动脉连接术患者 ;对照组选择 18例房间隔缺损、室间隔缺损心内修复术患者 ,两组分别于术前、术后第 1天、第 5天、第 4周和术后 6个月测量其心钠素含量。结果　观察组ANP含量术后第 1天显著下降 (t=2 6 2 3,P <0 0 1) ,此后直至出院前均显著高于对照组 ,术后 6个月时两组间无差别。观察组 7例术后出现胸腔积液并发症 ,其早期心钠素含量显著低于未发生该并发症的 11例患者 (P <0 0 5 )。结论　TCPC术后 ,因完全旷置右心 ,右房压显著下降 ,早期心钠素分泌量不足 ,这可能会导致机体水盐代谢失衡 ,与术后早期胸腔积液并发症密切相关。     

Steady state of gradient echo sequences with radiofrequency phase cycling: Analytical solution,contrast enhancement with partial spoiling

Spoiled gradient echo sequences can only reach a homogeneous steady state if sufficiently strong crusher gradients are used in combination with RF phase cycling (RF spoiling). However, the signal depends quite sensitively on the chosen phase increment ? and—lacking analytical solutions—numerical simulations must be used to study the transient and steady‐state magnetization. For the steady state an exact analytical solution is derived, which holds for arbitrary sequence and tissue parameters. Besides a considerably improved computation performance, the analytical approach enables a better understanding of the complicated dependence on ?. For short repetition times (TR) the regime of small ? turns out to be particularly interesting: It is shown that the typical ?_c, where RF spoiling starts to become effective, is essentially inversely proportional to T₂. This tissue dependence implies that contrasts can be considerably larger with partial spoiling (? ≈ ?_c) than with conventional RF spoiling (? ? ?_c). As an example, the uptake of contrast agents in tissues is investigated. For typical parameters a considerably improved contrast enhancement can be obtained, both theoretically and experimentally. Magn Reson Med, 2006. © 2005 Wiley‐Liss, Inc.