Immuno-PET在程序性细胞死亡受体配体-1活体成像中的研究进展

：免疫正电子发射计算机断层显像（Immuno-PET）是一种高效特异性,无创性和活体即时成像的诊断技术。这种技术不仅能可视化活体肿瘤细胞的定位,并且可识别肿瘤免疫受体（如PD-L1）并进行分子量化。PD-L1的靶向成像和预后评价方面具有巨大的发展前景。近年来,Immuno-PET在PD-L1靶向活体成像方面的研究逐渐成为热点。本文就Immuno-PET活体表征PD-L1的原理、应用价值、常用核素、新型示踪剂性质以及其在活体动物、人体上的成像效果等方面作一综述。     

次声作用后鼠脑超微结构与血脑屏障改变

目的　探讨次声作用后脑超微结构与血脑屏障(bloodbrainbarrier,BBB)通透性改变及意义。方法　40只SD大鼠随机分为正常对照、次声作用1次、7次及14次四组。采用本校研制的次声压力仓。次声作用组用8Hz、120dB的次声按规定次数,每次作用2h。硝酸镧心脏灌注法固定鼠脑,透射电镜下观察脑超微结构与BBB改变。结果　随次声作用次数增加,脑超微结构损害愈重;BBB改变,次声作用1次与7次组相似,均有紧密连接开放,血管基膜外以至组织间隙内存在硝酸镧颗粒;至14次组愈加严重,可见大量硝酸镧颗粒经BBB进入组织间隙,与1、7次两组比较差异有显著性(P<0.05)。结论　次声作用可直接破坏脑超微结构与BBB;在相同强度的次声作用下,作用次数的多少与BBB及脑损害程度直接相关。     

Attenuation effects of heparin–superoxide dismutase conjugate on bleomycin-induced lung fibrosis in vivo and radiation-induced inflammatory cytokine expression in vitro

In this study, the effects of heparin–superoxide dismutase conjugate (heparin–SOD) on bleomycin-induced pulmonary fibrosis in vivo and on inflammatory cytokine expression in vitro were evaluated. To investigate the effects of heparin–SOD on pulmonary fibrosis, heparin–SOD was administered to bleomycin (BLM)-treated mice by intraperitoneal injection once a day and the hydroxyproline content in lung was determined per 7 days. The degree of fibrosis was assessed quantitatively using histopathologic features. The results showed that heparin–SOD inhibited BLM-induced lung fibrotic lesions as reflected by the decrease of lung hydroxyproline content and lung fibrosis grade 28 days after BLM instillation. The in vitro effects on the cytokine level expressed by irradiated 3T3 fibroblasts showed that heparin–SOD significantly lowered the levels of transforming growth factor-β1 and interleukin-1β. These results strongly demonstrated that heparin–SOD might be useful in the prevention and treatment of pulmonary fibrosis.     

In vivo and in vitro visualization of gene expression dynamics over extensive areas of the brain

In vivo monitoring of gene expression using promoter-destabilized fluorescence protein constructs is a powerful method for examining the expression dynamics of immediate-early genes in the brain. However, weak fluorescence signals derived from such constructs have hampered analyses of gene expression over extensive areas of the brain. We succeeded in producing transgenic mice with brains exhibiting high level expression of the reporter gene driven by the Arc gene promoter, which is activated in association with various brain functions (reporter mRNA abundance was near 100-fold greater than endogenous Arc mRNAs). This high expression of the reporter gene enabled us to monitor Arc gene expression dynamics in vivo, over an area that included the whole of the dorsal cerebral cortex. Moreover, we were able to perform three-dimensional analyses of activated regions using paraformaldehyde-fixed brains. In addition to the visual cortex, we found that the cingulate cortex was strongly activated by light stimuli. These mice are extremely useful for the functional analysis of gene expression over extensive areas of the brains in both wild-type mice and mutants with impaired brain function.     

Measurement of ultrasound energy density distributions in vivo

Thermocouple junctions coated with absorbing material have been used for measurement of ultrasound energy density distribution in vivo. The response of this type of probe has been measured in tumours implanted in rats, in ox liver, and in a water bath, using 1 and 3 MHz focussed ultrasound, and these measurements are reported in this paper. The initial rapid rate of temperature rise during the first 60 ms after the ultrasound is switched on provides a reliable index of ultrasound energy density. The coating material increases the magnitude of the temperature rise and reduces variations caused by differences in tissue properties and changes in blood flow. The response is a linear function of ultrasound energy density over the range of interest for therapeutic applications. Thus probes calibrated in known ultrasound fields in water tanks can be used to estimate energy densities in tissue directly.     

In vitro and in vivo efficacy of edelfosine-loaded lipid nanoparticles against glioma

Edelfosine is the prototype molecule of a family of anticancer drugs collectively known as synthetic alkyl-lysophospholipids. This drug holds promise as a selective antitumor agent, and a number of preclinical assays are in progress. In this study, we observe the accumulation of edelfosine in brain tissue after its oral administration in Compritol® and Precirol® lipid nanoparticles (LN). The high accumulation of edelfosine in brain was due to the inhibition of P-glycoprotein by Tween® 80, as verified using a P-glycoprotein drug interaction assay. Moreover, these LN were tested in vitro against the C6 glioma cell line, which was later employed to establish an in vivo xenograft mouse model of glioma. In vitro studies revealed that edelfosine-loaded LN induced an antiproliferative effect in C6 glioma cell line. In addition, in vivo oral administration of drug-loaded LN in NMRI nude mice bearing a C6 glioma xenograft tumor induced a highly significant reduction in tumor growth (p < 0.01) 14 days after the beginning of the treatment. Our results showed that Tween® 80 coated Compritol® and Precirol® LN can effectively inhibit the growth of C6 glioma cells in vitro and suggest that edelfosine-loaded LN represent an attractive option for the enhancement of antitumor activity on brain tumors in vivo.     

血红素氧合酶-1对大鼠脑缺血再灌注后血脑屏障通透性的影响

目的:探讨血红素氧合酶(hemeoxygouase-1,HO-1)对大鼠局灶性脑缺血再灌注后血脑屏障(bloodbrainbarrier,BBB)通透性的影响。方法:健康成年雄性SD大鼠,体质量250～300g,采用线栓法制备局灶性脑缺血模型,通过免疫组化观察脑组织HO-1的表达,通过比色法测定脑组织中伊文思蓝(EB)的含量来反映血脑屏障通透性的改变。结果:缺血2h再灌注2h即见脑缺血区的周围大脑皮质及远隔区域有HO-1蛋白的表达,免疫阳性持续到再灌注后48h。缺血2h再灌注3hEB含量(1.36±0.10)g/L,BBB通透性开始增加,24h达高峰(5.64±1.30)g/L,48h后开始减弱。Znpp组EB含量(6.53±0.02)g/L较缺血2h再灌注24h增高。结论:脑缺血再灌注后HO-1快速高效表达,可能对BBB有保护作用。     

实验性脑出血脑组织血流动力学变化的灌注磁共振成像研究

目的　研究脑出血后脑组织血流动力学的变化规律。方法　采用立体定向自体血脑内注入法制作犬额叶脑出血模型 10只 ,分别于造模前和造模后 0 .5h、3h、6h、12h、2 4h、4 8h、72h、7d、15d进行PWI动态扫描。结果　血肿区 0 .5～72h无灌注 ,7～ 15d无或微灌注 ;血肿周边区 0 .5～ 6h低灌注 ,12h血供开始逐渐回升并接近对侧呈稍低灌注 ,部分有高灌注 ;远隔区 0 .5h～ 15d普遍稍低灌注。结论　脑出血后脑组织血流灌注普遍性降低 ,12h是血肿周边组织血流灌注变化的时间转折点。PWI是客观研究和评价脑出血后脑组织血流动力学变化的有效手段。     

Elastographic imaging of thermal lesions in the liver in vivo following radiofrequency ablation: preliminary results

Radiofrequency (RF) ablation is an interstitial focal ablative therapy that can be used in a percutaneous fashion. This modality provides in situ destruction of hepatic tumors. However, local recurrence rates after RF ablative therapy are as high as 34% to 55%, believed to be due in part to the inability to visualize accurately the zone of necrosis (thermal lesion). This can lead to the incomplete ablation of the tumor, generally in areas near the tumor edges. In this paper, we show that ultrasound (US)-based in vivo elastography can accurately depict thermal lesions after thermal therapy. However, elastography of the liver and other abdominal organs is challenging due to the difficulty in providing controlled and reproducible compression. The use of the RF ablation probe as the compressor/displacement device reduces lateral slippage or nonaxial motion that may occur with externally applied compressions or imaging during the respiratory cycle. This technique also provides controlled and reproducible compressions of the liver for in vivo elastographic imaging. Comparison of elastograms with histology of ablated tissue demonstrates a close relationship between elastographic image features and histopathology. (E-mail: tvarghese@facstaff.wisc.edu)     

Local hyperthermia induced by focussed and overlapping ultrasonic fields—An in vivo demonstration

Axial temperature distributions were measured in living and post mortem porcine tissues during sonication with plane, focussed and overlapping ultrasonic fields. With the focussed field it was always possible to induce the temperature maxima at depths up to 50 mm, although the actual temperatures achieved varied from animal to animal. The plane 0.75 MHz transducer produced a maximum temperature close to the skin surface. With 7 overlapping plane fields a relatively uniform temperature distribution was produced in a large tissue volume. The blood perfusion in tissue has a significant effect not only on the magnitude of the temperature increase, but also on the temperature distribution.     

Early IV‐injected human dermis‐derived mesenchymal stem cells after transient global cerebral ischemia do not pass through damaged blood–brain barrier

There is lack of researches on effects of intravenously injected mesenchymal stem cells (MSCs) against transient cerebral ischemia (TCI). We investigated the disruption of the neurovascular unit (NVU), which comprises the blood–brain barrier and examined entry of human dermis‐derived MSCs (hDMSCs) into the damaged hippocampal CA1 area in a gerbil model of TCI and their subsequent effects on neuroprotection and cognitive function. Impairments of neurons and blood–brain barrier were examined by immunohistochemistry, electron microscopy, and Evans blue and immunoglobulin G leakage. Neuronal death was observed in pyramidal neurons 5‐day postischemia. NVU were structurally damaged; in particular, astrocyte end‐feet were severely damaged from 2‐day post‐TCI and immunoglobulin G leaked out of the CA1 area 2 days after 5 min of TCI; however, Evans blue extravasation was not observed. On the basis of the results of NVU damages, ischemic gerbils received PKH2‐transfected hDMSCs 3 times at early times (3 hr, 2, and 5 days) after TCI, and fluorescence imaging was used to detect hDMSCs in the tissue. PKH2‐transfected hDMSCs were not found in the CA1 from immediate time to 8 days after injection, although they were detected in the liver. Furthermore, hDMSCs transplantation did not protect CA1 pyramidal neurons and did not improve cognitive impairment. Intravenously transplanted hDMSCs did not migrate to the damaged CA1 area induced by TCI. These findings suggest no neuroprotection and cognitive improvement by intravenous hDMSCs transplantation after 5 min of TCI.     

Module assemblage technology for floating systems: In vitro flotation and in vivo gastro-retention

The aim of this research was to study, in vitro by resultant-weight measurement and in vivo by γ-scintigraphy experiments in humans, the floatation behavior of systems obtained by modules assembled in void configuration. The assembled system technology allowed the manufacturing of a system characterized by the presence of an internal void space that provided an apparent density lower than water. The gastro-retention times of floating assembled systems were determined in comparison with non-floating systems having the same mass and composition. In vitro the floatation of the system started immediately after immersion in water and lasted for more than 5 h.The in vivo studies confirmed that the in vitro floating ability of void configuration was maintained also in the human stomach where the system stayed for periods of time ranging from 2.5 to 5.0 h, depending on the food regimen and the sex of the subject. Reiterate eating and drinking further prolonged the stomach residence time.     

Pulse duration and peak intensity during focused ultrasound surgery: Theoretical and experimental effects in rabbit brain in vivo

The goal of this study was to establish the exposure parameters that will generate predictable thermally induced lesions in brain. In addition, the accuracy of a theoretical model for prediction of the lesion size was tested. To do this, 160 adult rabbits were sonicated (frequency 0.936 and 1.72 MHz) and then sacrificed at various intervals after the sonications. The results showed that predictable thermal lesions could be induced if the exposure durations were between 0.5 and 2 s. Dimensions of the necrosed tissue volume were roughly predictable by the theoretical calculations based on purely thermal effects. Shorter sonications required higher intensities (above 3700 W cm⁻² at 1.72 MHz) resulting in mechanical effects with extensive vascular damage. Lesion size varied more at longer exposures (5 and 10 s), perhaps due to the increased effect of tissue perfusion. As a conclusion, focused ultrasound can be used for destruction of tissues deep in brain without causing undesirable mechanical effects, if the exposure parameters are selected properly.     

A new model of rectal cancer with regional lymph node metastasis allowing in vivo evaluation by imaging biomarkers

Object

The work is aimed to develop a murine model of rectal cancer, which could be used to monitor lymph node metastasis development by magnetic resonance imaging (MRI) and optical imaging (OI) techniques.

Subjects and methods

Ht-29 cancer cells were directly injected into the submucosal layer of the rectum of athymic nude mice using trans-anal rectal cancer cell injection (TARCI). Thirty-six mice were inoculated with 10 × 10⁵ cells and five mice were treated with sterile phosphate buffer solution. One to 4 weeks after cell injection, tumor growth was evaluated in vivo using T2-weighted MRI at 4.7T. A further group of animal (n = 6) treated with ht-29_luc cells, with the same protocol, was monitored by optical imaging. In both groups, the presence of the primary tumor and of lymph nodes metastasis was confirmed by histology.

Results

In all animals, primary tumors were detectable by MRI, 1 week from TARCI. After 4 weeks primary tumors showed a mean longitudinal diameter of about 2 cm. All animals developed regional lymph node metastases. Others organs (e.g. lung or liver) were not affected. In fat-suppressed, T2-weighted MRI, lymph nodes appeared as small areas characterized by hyper-intense signal compared to muscle. OI permitted evaluation of the primary tumor growth in perineal region.

Conclusions

TARCI of ht-29 cells into the rectum of nude mice is a feasible way to obtain a easily reproducible model of regional lymph node metastases could be monitored by magnetic resonance and optical imaging techniques.     

增强磁共振成像评价脑缺血再灌注后大鼠血脑屏障的通透性

目的通过增强磁共振成像(MRI)来研究脑缺血再灌注后大鼠血脑屏障(BBB)通透性的改变。方法采用线栓法制备大鼠局灶性脑缺血再灌注模型。用1.5T超导型MR机进行大鼠脑冠状位扫描,随后经股静脉注入Gd-DTPA,迅速行同层间歇扫描。结果脑缺血4h,再灌注50min时,缺血侧纹状体增强率与对侧相比差别具有非常显著性意义(P<0.01)。再灌注70min时,缺血侧大脑皮层增强率较对侧增高(P<0.05)。缺血侧侧脑室在再灌注10min时可见明显强化。结论纹状体区BBB比大脑皮层更易受到再灌注损伤。血脑脊液屏障较早受到破坏。增强MRI是一种敏感的在活体条件下检测BBB损伤的理想方法。     

Plasmodium falciparum erythrocyte membrane protein 1 variants induce cell swelling and disrupt the blood–brain barrier in cerebral malaria

Cerebral malaria (CM) is caused by the binding of Plasmodium falciparum–infected erythrocytes (IEs) to the brain microvasculature, leading to inflammation, vessel occlusion, and cerebral swelling. We have previously linked dual intercellular adhesion molecule-1 (ICAM-1)– and endothelial protein C receptor (EPCR)–binding P. falciparum parasites to these symptoms, but the mechanism driving the pathogenesis has not been identified. Here, we used a 3D spheroid model of the blood–brain barrier (BBB) to determine unexpected new features of IEs expressing the dual-receptor binding PfEMP1 parasite proteins. Analysis of multiple parasite lines shows that IEs are taken up by brain endothelial cells in an ICAM-1–dependent manner, resulting in breakdown of the BBB and swelling of the endothelial cells. Via ex vivo analysis of postmortem tissue samples from CM patients, we confirmed the presence of parasites within brain endothelial cells. Importantly, this discovery points to parasite ingress into the brain endothelium as a contributing factor to the pathology of human CM.     

Persistence of cerebral blood flow after brain death

Persistent cerebral blood flow occasionally confounds confirmatory tests for brain death and results in the anguish of delayed diagnosis, unnecessary use of expensive resources, and loss of transplant opportunities. We reviewed the literature to examine the reasons, frequency, and meaning of this problem. We found that this phenomenon occurs: (1) before increasing intracranial pressure completely shuts down flow; (2) in infants with pliable skulls; and with (3) decompressing fractures, (4) ventricular shunts, (5) ineffective deep brain flow, (6) reperfusion, (7) brain herniation, (8) jugular reflux, (9) emissary veins, and (10) pressure injection artifacts. Isolated venous sinus visualization is common (occurring in up to 57%) but represents trivial blood flow and confirms brain death. Arterial flow is much less common (2.6% incidence in our series). Normal flow occurs but is rare. Arterial flow does not exclude brain death, but the diagnosis should be confirmed by repeated studies or other means.