In Vivo Evaluation and Dosimetry Estimate for a High Affinity Affibody PET Tracer Targeting PD-L1

Molecular Imaging and Biology - In vivo imaging of programmed death ligand 1 (PD-L1) during immunotherapy could potentially monitor changing PD-L1 expression and PD-L1 expression heterogeneity...     

Laboratory and field evaluation of a new personal sampling system for assessing the protection provided by the N95 filtering facepiece respirators against particles

OBJECTIVES: We have recently developed a new personal sampling system for the real-time measurement of the protection provided by respirators against airborne dust and micro-organisms. The objective of this study was to evaluate the performance characteristics of the new sampling system in both laboratory and field conditions. METHODS: The measurements were conducted using the N95 filtering facepiece respirators and the newly developed personal sampling system put on a manikin (laboratory study) or donned by a human subject (laboratory and field studies). Two inhalation flow rates (0 and 40 l min(-1)) in conjunction with the sampling flow rate (10 l min(-1)) were tested in the manikin-based experiments to investigate the effects of the leak location (nose, cheek and chin) and the depth of the sampling probe (0, 5, 10 and 15 mm) within the respirator. The effect of human activity on the protection factor was evaluated using a variety of head movements and breathing patterns when a human subject wore the respirator in a room-size laboratory test chamber. The field study was conducted during corn harvesting with a respirator worn by a human subject on a combine. RESULTS: There was no significant difference in the protection factors for different leak locations, or for sampling probe depths, when the inhalation rate was 0 l min(-1). For the inhalation rate of 40 l min(-1), the protection factors for nose leaks were higher than those for chin and cheek leaks. Furthermore, the protection factor was the lowest and showed the least variation when the sampling probe depth was equal to 0 mm (imbedded on the respirator surface). Human subject testing showed that the grimace maneuver decreased the protection factor and changed the original respirator fit. The protection factor during breath holding was lower than that found during inhalation and exhalation. Field results showed greater variation than laboratory results. CONCLUSIONS: The newly designed personal sampling system efficiently detected the changes in protection factors in real time. The sampling flow was least affected by the inhalation flow when the sampling probe was imbedded on the respirator surface. Leak location, breathing patterns and exercises did affect the measurement of the protection factors obtained using an N95 filtering facepiece respirator. This can be attributed to the differences in the in-mask airflow dynamics contributed by the leak, filter material, sampling probe and inhalation. In future studies, it would be beneficial if the laboratory data could be integrated with the field database.     

Molecular imaging of bone marrow mononuclear cell homing and engraftment in ischemic myocardium

Bone marrow mononuclear cell (BMMC) therapy shows promise as a treatment for ischemic heart disease. However, the ability to monitor long-term cell fate remains limited. We hypothesized that molecular imaging could be used to track stem cell homing and survival after myocardial ischemia-reperfusion (I/R) injury. We first harvested donor BMMCs from adult male L2G85 transgenic mice constitutively expressing both firefly luciferase (Fluc) and enhanced green fluorescence protein reporter gene. Fluorescence-activated cell sorting analysis revealed approximately 0.07% of the population to consist of classic hematopoietic stem cells (lin-, thy-int, c-kit+, Sca-1+). Afterward, adult female FVB recipients (n = 38) were randomized to sham surgery or acute I/R injury. Animals in the sham (n = 16) and I/R (n = 22) groups received 5 x 10(6) of the L2G85-derived BMMCs via tail vein injection. Bioluminescence imaging (BLI) was used to track cell migration and survival in vivo for 4 weeks. BLI showed preferential homing of BMMCs to hearts with I/R injury compared with sham hearts within the first week following cell injection. Ex vivo analysis of explanted hearts by histology confirmed BLI imaging results, and quantitative real-time polymerase chain reaction (for the male Sry gene) further demonstrated a greater number of BMMCs in hearts with I/R injury compared with the sham group. Functional evaluation by echocardiography demonstrated a trend toward improved left ventricular fractional shortening in animals receiving BMMCs. Taken together, these data demonstrate that molecular imaging can be used to successfully track BMMC therapy in murine models of heart disease. Specifically, we have demonstrated that systemically delivered BMMCs preferentially home to and are retained by injured myocardium. Disclosure of potential conflicts of interest is found at the end of this article.     

Size distribution of airborne mist and endotoxin-containing particles in metalworking fluid environments

The objective of the study was to investigate size-selective concentrations of airborne particles and endotoxin in metalworking fluid (MWF) environments. The experiments were conducted under two conditions: (1) MWF collected in the field was aerosolized with a laboratory-scale simulator (MWF simulator) in the laboratory; and (2) MWFs were aerosolized during routine field operations. All experiments included size-selective measurement of airborne concentrations of particle numbers and endotoxin mass using an electrical low-pressure impactor. During field sampling, the total microbial and endotoxin concentrations in the air were also measured with a BioSampler, and the mass concentration of MWF mists was measured with a photometer. Airborne particle concentrations were highest in the fine particle size ranges in the areas affected by MWFs. Relatively high concentrations of endotoxin were detected at particle size below 0.39 mum, which is smaller than the size of intact bacterial cells. The total microbial and endotoxin analysis revealed high microbial contamination in one sampling site although the total particle mass was not elevated. It was concluded that MWF sites can be contaminated with high concentrations of fine particles, and these fine particles may contain microbial components, such as endotoxin. The results call for the size-selective measurement of particles and endotoxin for more comprehensive exposure assessment in MWF facilities.     

Slug-siRNA干扰Slug基因表达对胰腺癌的抑制作用

目的: 研究携带Slug-siRNA的rAAV对裸鼠体内胰腺癌的作用.方法: 建立人胰腺癌裸鼠皮下移植瘤模型,2wk后随机将建模成功的裸鼠分为3组,每组6只. 构建携带Slug-siRNA的rAAV载体,采用瘤体内多点注射的方法,阴性对照组裸鼠按1×109 puf(50 μL)标准注射rAAV-EGFP,空白对照组裸鼠注射等量生理盐水,实验组裸鼠按1×109 puf(50 μL)标准注射rAAV2-EGFP-slugsiRNA,只注射1次. 观察裸鼠的一般情况,摄食,活动能力,每周用电子天平秤体质量,绘制裸鼠生长曲线. 治疗6 wk后二氧化碳吸入法处死裸鼠,切取肿瘤称质量;免疫组织化学SP法检测slug蛋白的表达,TUNEL检测皮下移植瘤细胞凋亡,透射电镜检测细胞超微结构.结果: 3组裸鼠分别接受不同的处理后,在开始的2 wk皮下移植瘤的生长无明显差别,2 wk以后,实验组裸鼠皮下移植瘤的体积增长明显滞后于阴性对照组和空白对照组,差异有统计学意义( P<0.05). 治疗6 wk后,实验组裸鼠皮下移植瘤的质量明显轻于阴性对照组和空白对照组差异有统计学意义(3.26±0.48 g vs7.56±1.25 g,7.50±1.23 g,均P<0.05). 实验组裸鼠皮下移植瘤的AI值明显高于阴性对照组和空白对照组,差异有统计学意义(0.27±0.06vs 0.024±0.01,0.025±0.01,均P<0.05);实验组的抑瘤率明显高于阴性对照组,差异有统计学差异(71.4% vs 0.04%,P<0.01). 透射电镜下,实验组肿瘤细胞可见细胞器结构模糊,核固缩,染色质边集等现象. 免疫组织化学检测示实验组Slug表达明显减少.结论: Slug基因被有效沉默,Slug基因沉默后促进细胞凋亡,抑制胰腺癌实体瘤增殖和生长.     

α-干扰素不同治疗方式对HPV隐性感染患者的临床随机实验研究

目的:探讨α-干扰素治疗HPV隐性感染患者的最佳途径。方法:选取273例生殖道HPV隐性感染的女患者,随机分成3组:第1组应用α-干扰素皮下注射治疗,第2组应用α-干扰素生殖道靶位置注射治疗,第3组则采用前两种方式结合起来治疗,以上3组用药剂量均相同。实验前后利用PCR技术通过检测宫颈分泌物来确定HPV及主要分型。结果:治疗前各组HPV阳性率差异没有统计学意义(P>0.05),干预以后第3组的治疗效果明显优于前两组(P<0.05)。结论:皮下联合生殖道靶位置注射。α-干扰素的治疗效果显著,具有临床实际应用价值。     

Personal exposure to airborne dust and microorganisms in agricultural environments

Airborne dust and microorganisms are associated with respiratory diseases and increased mortality and morbidity. Farmers are at high risk of exposure to both of these hazards. Very limited information, however, is available on the combined exposures to both hazards on different types of farms. Moreover, most of the previous studies have measured the mass concentration of particles ignoring the particle size. In this study, farmers' exposure to airborne dust and microorganisms was studied using our newly developed personal sampling system. Particle number concentration and size distribution were measured with an optical particle counter. Simultaneously, particles were collected on a filter and analyzed for microorganisms. The field measurements were conducted in animal confinements (swine, poultry, and dairy) and during grain harvesting (corn and soybean). The results show the following average concentrations on the workers' breathing zone: 1.7 x 10(6) to 2.9 x 10(7) particles/m(3) for total dust, 0.9 x 10(3) to 3.9 x 10(4) spores/m(3) for total fungal spores, 0.3 x 10(3) to 3.6 x 10(4)CFU/m(3) for culturable fungal spores, 0.3 x 10(4) to 3.3 x 10(8) CFU/m(3) for culturable bacteria, and limit of detection (LOD) to 2.8 x 10(3) CFU/m(3) for culturable actinomycetes in animal confinements. The respective concentrations were 4.4 x 10(6) to 5.8 x 10(7) particles/m(3), 3.4 x 10(4) to 6.1 x 10(6) spores/m(3), 8.2 x 10(4) to 7.4 x 10(6) CFU/m(3), 0.4 x 10(5) to 1.4 x 10(6) CFU/m(3), and LOD to 2.6 x 10(4) CFU/m(3) during grain harvesting. The highest contribution of large particles (3-10 microm) in total particles was found during grain harvesting, whereas the size distribution was dominated by smaller particles (< 3 microm) in animal confinements. High fraction (up to 37%) of particles between 2-10 microm was found to be fungal spores. The results indicate that an increase in the concentration of large dust particles (2-10 microm) during grain harvesting was partially attributed to the increase in the concentration of the fungal spores. Overall, the combined exposure to airborne dust and microorganisms was found to be more severe during harvesting than in animal confinements.     

Respiratory protection provided by N95 filtering facepiece respirators against airborne dust and microorganisms in agricultural farms

A new system was used to determine the workplace protection factors (WPF) for dust and bioaerosols in agricultural environments. The field study was performed with a subject wearing an N95 filtering facepiece respirator while performing animal feeding, grain harvesting and unloading, and routine investigation of facilities. As expected, the geometric means (GM) of the WPFs increased with increasing particle size ranging from 21 for 0.7-1 microm particles to 270 for 5-10 microm particles (p < 0.001). The WPF for total culturable fungi (GM = 35) was significantly greater than for total culturable bacteria (GM = 9) (p = 0.01). Among the different microorganism groups, the WPFs of Cladosporium, culturable fungi, and total fungi were significantly correlated with the WPFs of particles of the same sizes. As compared with the WPFs for dust particles, the WPFs for bioaerosols were found more frequently below 10, which is a recommended assigned protection factor (APF) for N95 filtering facepiece respirators. More than 50% of the WPFs for microorganisms (mean aerodynamic diameter < 5 microm) were less than the proposed APF of 10. Even lower WPFs were calculated after correcting for dead space and lung deposition. Thus, the APF of 10 for N95 filtering facepiece respirators seems inadequate against microorganisms (mean aerodynamic size < 5 microm). These results provide useful pilot data to establish guidelines for respiratory protection against airborne dust and microorganisms on agricultural farms. The method is a promising tool for further epidemiological and intervention studies in agricultural and other similar occupational and nonoccupational environments.