Dye standards, Part II.5: Pararosaniline (CI 42500)

The names and affiliations of the SRMTS members are cited in Part I: terminology and general principles,Histochem. J. (1992)24, 217–19.     

Proteome-wide Mendelian randomization identifies causal links between blood proteins and severe COVID-19

In November 2021, the COVID-19 pandemic death toll surpassed five million individuals. We applied Mendelian randomization including >3,000 blood proteins as exposures to identify potential biomarkers that may indicate risk for hospitalization or need for respiratory support or death due to COVID-19, respectively. After multiple testing correction, using genetic instruments and under the assumptions of Mendelian Randomization, our results were consistent with higher blood levels of five proteins GCNT4, CD207, RAB14, C1GALT1C1, and ABO being causally associated with an increased risk of hospitalization or respiratory support/death due to COVID-19 (ORs = 1.12–1.35). Higher levels of FAAH2 were solely associated with an increased risk of hospitalization (OR = 1.19). On the contrary, higher levels of SELL, SELE, and PECAM-1 decrease risk of hospitalization or need for respiratory support/death (ORs = 0.80–0.91). Higher levels of LCTL, SFTPD, KEL, and ATP2A3 were solely associated with a decreased risk of hospitalization (ORs = 0.86–0.93), whilst higher levels of ICAM-1 were solely associated with a decreased risk of respiratory support/death of COVID-19 (OR = 0.84). Our findings implicate blood group markers and binding proteins in both hospitalization and need for respiratory support/death. They, additionally, suggest that higher levels of endocannabinoid enzymes may increase the risk of hospitalization. Our research replicates findings of blood markers previously associated with COVID-19 and prioritises additional blood markers for risk prediction of severe forms of COVID-19. Furthermore, we pinpoint druggable targets potentially implicated in disease pathology.     

Methods for homocysteine analysis and biological relevance of the results

It is now widely accepted that increased total plasma homocysteine (tHcy) is a risk factor for cardiovascular disease. Hyperhomocysteinemia can be caused by impaired enzyme function as a result of genetic mutation or vitamin B (B(2), B(6), B(9), B(12)) deficiency. A lot of methods are now available for tHcy determination. High-pressure liquid chromatography (HPLC) with fluorescence detection are at present the most widely used methods but immunoassays, easier to use, begin to supplant in-house laboratory methods. In order to help with the choice of a main relevant homocysteine analytical method, the characteristics, performances and limits of the main current methods are reviewed. One major drawback among all these available methods is the transferability which is not clearly established to date. The impact of both inter-method and inter-laboratory variations on the interpretation of the tHcy results are discussed.     

The "vanishing counting bead" phenomenon: effect on absolute CD34+ cell counting in phosphate-buffered saline-diluted leukapheresis samples

BACKGROUND: Using a single-platform protocol to count absolute CD34+ hematopoietic precursor cell (HPC) levels with different reference microbeads, we recorded occasionally artifactually high CD34+ HPC counts in some leukapheresis bags, whereas dual-platform calculations were always consistent. Abnormal countings were observed only when phosphate-buffered saline (PBS)-diluted leukapheresis samples were vortexed before analysis. A large series of blood samples analyzed similarly for CD34+ and CD4+ absolute counts did not show any sample or vortexing effect. With the volumetric absolute counting cytometer Partec-PAS, lower counts were also observed when different reference beads were vortexed before the instrument checking procedures. The counting abnormality was caused by a drop in microbead concentration (the "vanishing bead phenomenon"). This phenomenon reduced the total and relative bead event number in experimental and routine samples and in calibration procedures. This altered the bead denominator used to calculate absolute CD34+ HPC levels and it also reduced the concentration of standard calibration beads. METHODS: Using the Partec-PAS to measure volumetrically the actual bead concentration, we studied the vanishing bead phenomenon. Different types of counting and reference microbeads were resuspended in media with or without proteins or cells. Replicates were submitted either to gentle manual mixing or to vortexing before counting. RESULTS: Vortex agitation almost invariably induced the vanishing bead phenomenon when beads were resuspended in saline media or when an insufficient protein concentration was present, such as in diluted leukapheresis samples. Different bead types showed various degrees of sensitivity to vortexing. The bead disappearance was not caused by bubble formation or disruption. The addition of small amounts of protein completely prevented the vanishing bead phenomenon. The causative effect of the electrostatic charging of tube induced by vortexing is hypothesized. CONCLUSIONS: Sample suspensions containing counting beads for single-platform analysis must be resuspended in media with protein supplements to prevent the vanishing bead phenomenon and to ensure accurate counting.     

双特异性抗体在肿瘤治疗中的研究

双特异性抗体(bispecific antibody,BsAb)有两个抗原结合位点,其中一个位点可与靶细胞表面抗原结合,另一个位点则可与载荷物(如效应细胞,分子等)结合。将BsAb应用于肿瘤治疗,发挥抗肿瘤效应的思想已有二十多年历史,随着对效应细胞生物学了解的加深和抗体工程的飞速发展,各种形式的BsAb相继出现,多种BsAb药物已进入临床初期试验或治疗使用阶段。本文就BsAb的各种新形式及其在肿瘤治疗中的应用新进展作简要概述。     

基因突变在结直肠癌发生机制中的作用:殊途同归

结直肠癌的多步骤演进模式一直是肿瘤研究的经典,在这一过程中,序贯发生的基因突变(或其它遗传事件)是重要的推动力。本文综述了在结直肠癌中检测到的基因突变情况,并分析了在新一代测序技术的带动下,结直肠癌基因组学的最新进展。结直肠癌组织基因突变的地形图理念对于今后的肿瘤分子诊疗将具有重要意义。肿瘤不仅是基因病,更是信号通路异常病。