Immune checkpoint blockade and its combination therapy with small-molecule inhibitors for cancer treatment

Initially understood for its physiological maintenance of self-tolerance, the immune checkpoint molecule has recently been recognized as a promising anti-cancer target. There has been considerable interest in the biology and the action mechanism of the immune checkpoint therapy, and their incorporation with other therapeutic regimens. Recently the small-molecule inhibitor (SMI) has been identified as an attractive combination partner for immune checkpoint inhibitors (ICIs) and is becoming a novel direction for the field of combination drug design. In this review, we provide a systematic discussion of the biology and function of major immune checkpoint molecules, and their interactions with corresponding targeting agents. With both preclinical studies and clinical trials, we especially highlight the ICI + SMI combination, with its recent advances as well as its application challenges.     

Rapid stimulation of K -H exchange by a plant growth hormone.

The growth-promoting phytotoxin fusicoccin¹ stimulates both [⁸⁶Rb⁺]K⁺ uptake and H⁺-excretion from oat coleoptiles by at least 5-fold after a lag of less than 90 seconds. Both processes are affected similarly by metabolic inhibitors and external pH. FC appears to activate a K⁺H⁺ exchange which is only partly specific for K⁺, and which can transport more H⁺ than K⁺. The natural plant growth hormone indoleacetic acid¹ also stimulates K⁺-uptake, but only after a long lag, and to a maximum of 30%, suggesting that IAA does not affect directly the K⁺H⁺ exchange process, and that the two hormones induce H⁺-excretion, and thus cell elongation, by different mechanisms.     

Transport of heme by hemopexin to the liver: Evidence for receptor-mediated uptake

We used carefully defined heme-hemopexin complexes to investigate the role of hemopexin in the catabolism of heme in vivo. Uptake of rabbit [⁵⁹Fe]heme-[¹²⁵I]hemopexin by rat liver was rapid. The liver-associated ¹²⁵I reached a maximum 5 minutes after injection, nearly 7-fold higher than apo-hemopexin, whereas liver-associated ⁵⁹Fe increased with time. This together with an inverse relationship of [¹²⁵I]hemopexin in the liver and serum during the course of heme transport suggests that hemopexin was released from the liver back to the circulation. Saturation of uptake with heme-hemopexin, reaching about 170 pmol [¹²⁵I]hemopexin (gm liver)^?1 5 minutes after injection of 11 nmol, indicates a receptor-mediated process.We conclude that hemopexin delivers heme to the liver via interaction with a finite number of receptors and returns to the circulation.     

Methylation of TMV RNA

Several plant and animal viral RNAs contain a tRNA like structure at their 3′ ends. In this communication we show that tobacco mosaic virus (TMV) RNA is an acceptable substrate for a specific tRNA methyltransferase. Using a crude preparation of $\text{E. coli}$ ribothymidine (rT) forming uracil methylase and (methyl ³H) S-adenosyl-L-methionine (SAM) as a methyl donor, 0.7 moles of methyl group is incorporated per mole of TMV RNA in 10 hours at 30°C. Upon T₂ RNAse digestion of the labeled RNA, all of the radioactivity was found to be in TMP. T₁ RNAse digestion of ³H methylated TMV RNA showed that all of the label was located in a tetranucleotide which co-migrated with authentic TpψpCpGp, an oligonucleotide characteristically found in normal cellular tRNA.The use of this specific methyl transferase reaction may provide a simple assay for the detection of tRNA like structures in large RNAs.     

FTO demethylase activity is essential for normal bone growth and bone mineralization in mice

The Fto gene locus has been linked to increased body weight and obesity in human population studies, but the role of the actual FTO protein in adiposity has remained controversial. Complete loss of FTO protein in mouse and of FTO function in human patients has multiple and variable effects. To determine which effects are due to the ability of FTO to demethylate mRNA, we genetically engineered a mouse with a catalytically inactive form of FTO. Our results demonstrate that FTO catalytic activity is not required for normal body composition although it is required for normal body size and viability. Strikingly, it is also essential for normal bone growth and mineralization, a previously unreported FTO function.     

Calcium sensitive binding of troponin to actin-tropomyosin: a two-site model for troponin action

Troponin reconstituted from the inhibitory component (troponin-I) and calcium binding protein (troponin-C) binds readily to actin-tropomyosin in 0.1 mm-EGTA but only poorly in 0.01 mm-CaCl₂ or 0.1 mm-Ca-EGTA. Troponin prepared by extraction of myofibrils with mersalyl, an organic mercurial, contains only these two components and also shows this calcium-sensitive binding and is deficient in its ability to bind to tropomyosin. Troponin-I + C is unable to confer calcium sensitivity on the Mg²⁺ activated actomyosin ATPase in concentrations at which native troponin is fully effective and the ATPase activity remains high in the absence of calcium. Addition of the tropomyosin binding component (troponin-T) to the other two components restores their ability to remain associated with actin-tropomyosin in the presence of calcium as does native troponin; calcium sensitivity is also regained. The results of these experiments have been interpreted in terms of a two-site mechanism of troponin action.     

Maternal n-3 PUFA supplementation promotes fetal brown adipose tissue development through epigenetic modifications in C57BL/6 mice

Brown adipose tissue (BAT) is a crucial regulator of energy expenditure. Emerging evidence suggests that n-3 PUFA potentiate brown adipogenesis in vitro. Since the pregnancy and lactation is a critical time for brown fat formation, we hypothesized that maternal supplementation of n-3 PUFA promotes BAT development in offspring. Female C57BL/6 mice were fed a diet containing n-3 PUFA (3%) derived from fish oil (FO), or an isocaloric diet devoid of n-3 PUFA (Cont) during pregnancy and lactation. Maternal n-3 PUFA intake was delivered to the BAT of neonates significantly reducing the n-6/n-3 ratio. The maternal n-3 PUFA exposure was linked with upregulated brown-specific gene and protein profiles and the functional cluster of brown-specific miRNAs. In addition, maternal n-3 PUFA induced histone modifications in the BAT evidenced by 1) increased epigenetic signature of brown adipogenesis, i.e., H3K27Ac and H3K9me2, 2) modified chromatin-remodeling enzymes, and 3) enriched the H3K27Ac in the promoter region of Ucp1. The offspring received maternal n-3 PUFA nutrition exhibited a significant increase in whole-body energy expenditure and better maintenance of core body temperature against acute cold treatment. Collectively, our results suggest that maternal n-3 PUFA supplementation potentiates fetal BAT development via the synergistic action of miRNA production and histone modifications, which may confer long-lasting metabolic benefits to offspring.     

Inhibiton of platelet aggregation by 1-alkylimidazole derivatives,thromboxane a synthethase inhibitors

1-Alkylimidazole derivatives of various sidechain lengths with various functional groups at the terminal end of the alkychain inhibited the synthesis of thromboxane A₂ from arachidonic acid by rabbit platelets and the conversion of prostaglandin H₂ to thromboxane A₂ by the microsomes of rabbit platelets. These enzyme inhinitors were anti-aggregatory as examine with rabbit and human platelet-rich plasma under various experimental conditions.     

Portable optical‐resolution photoacoustic microscopy for volumetric imaging of multiscale organisms

Photoacoustic microscopy (PAM) provides a fundamentally new tool for a broad range of studies of biological structures and functions. However, the use of PAM has been largely limited to small vertebrates due to the large size/weight and the inconvenience of the equipment. Here, we describe a portable optical‐resolution photoacoustic microscopy (pORPAM) system for 3‐dimensional (3D) imaging of small‐to‐large rodents and humans with a high spatiotemporal resolution and a large field of view. We show extensive applications of pORPAM to multiscale animals including mice and rabbits. In addition, we image the 3D vascular networks of human lips, and demonstrate the feasibility of pORPAM to observe the recovery process of oral ulcer and cancer‐associated capillary loops in human oral cavities. This technology is promising for broad biomedical studies from fundamental biology to clinical diseases.      

基于直线电机的大视场快速光声显微成像系统

光声成像技术是近年来发展的一种新型的无损医学成像技术,它是以脉冲激光作为激发源,以检测的声信号为信息载体,通过相应的图像重建算法重建组织内部结构和功能信息的成像方法。该方法结合了光学成像和声学成像的特点,可提供深层组织高分辨率和高对比度的组织层析图像,在生物医学临床诊断以及在体成像领域具有广泛的应用前景。目前光声成像的扫描方式主要有基于步进电机扫描方式和基于振镜的扫描方式,本文针对目前步进电机扫描速度慢(10 mm×10 mm;0.001帧/s),振镜扫描范围小(1 mm2)的不足,发展了基于直线电机扫描的大视场快速光声显微成像系统。同一条扫描线过程中直线电机速度最高可达200 mm/s。该技术采用逐线采集光声信号的方式,比逐点采集光声信号的步进电机快800倍。该系统对10 mm×10 mm全场扫描的扫描速度为0.8帧/s。最大可扫描视场范围可以达到50 mm×50 mm。大视场快速光声显微成像系统的发展将为生物医学提供新的成像工具。     

光声成像在光动力疗法研究中的应用

组织氧合作用和光敏剂应用在疾病诊治中都有着重要的作用,因此其实时在体无损检测很有意义。光动力疗法涉及光敏剂、光和氧分子三大要素,其疗效受组织氧合作用影响。本文对光声成像(PAI)、光声寿命成像(PALI)和多光谱光声层析成像(MSOT)等光声成像技术在光动力疗法的研究和应用中的使用现状进行了综述。对相关设备系统在检测光敏剂、组织氧分压和微血管损伤等方面的应用原理和技术分别进行了介绍,并总结了这些技术的应用前景。     

Impacts of the murine skull on high‐frequency transcranial photoacoustic brain imaging

Non‐invasive photoacoustic tomography (PAT) of mouse brains with intact skulls has been a challenge due to the skull's strong acoustic attenuation, aberration, and reverberation, especially in the high‐frequency range (>15 MHz). In this paper, we systematically investigated the impacts of the murine skull on the photoacoustic wave propagation and on the PAT image reconstruction. We studied the photoacoustic acoustic wave aberration due to the acoustic impedance mismatch at the skull boundaries and the mode conversion between the longitudinal wave and shear wave. The wave's reverberation within the skull was investigated for both longitudinal and shear modes. In the inverse process, we reconstructed the transcranial photoacoustic computed tomography (PACT) and photoacoustic microscopy (PAM) images of a point target enclosed by the mouse skull, showing the skull's different impacts on both modalities. Finally, we experimentally validated the simulations by imaging an in vitro mouse skull phantom using representative transcranial PAM and PACT systems. The experimental results agreed well with the simulations and confirmed the accuracy of our forward and inverse models. We expect that our results will provide better understanding of the impacts of the murine skull on transcranial photoacoustic brain imaging and pave the ways for future technical improvements.      

基于直线电机连续-步进运动的快速光声显微成像系统

报道了一种利用直线电机连续-步进的扫描方式进行光声显微成像的系统,该系统在运动时走弓字型路线,其中直线电机在X轴方向上连续运动,在Y轴方向上以步进的方式运动,采集卡只在X轴电机运动的过程中连续采集。该成像系统较之前振镜扫描的方式扫描的范围更大,可达到厘米尺度范围内的生物组织光声成像;较之前的步进电机逐点扫描的方式扫描速度明显提高。同时本文采用电机带动光和超声换能器一同扫描的方式,较光和超声换能器不动电机带动样品扫描的方式更灵活。另外利用包埋碳丝的模拟样品和在体小鼠耳朵血管来验证系统的成像能力。实验结果表明,这种快速光声显微成像方法及其系统可以实现在体组织的高分辨率成像,有望成为一种无创、实时的光声显微镜应用于生物医学当中。     

Na+/H+ exchange in the cyanobacterium Synechococcus 6311

The cyanobacterium Synechococcus 6311 adapts to grow in 0.6 M NaCl by developing an efficient system for sodium extrusion. In the present investigation cells loaded with NaC1 were subjected to a large dilution. Changes in fluorescence quenching of acridine orange as a function of transmembrane Na+ gradients provide evidence that Na+/H+ exchange activity greatly enhanced in salt-adapted cells.     

Thyrotropin releasing hormone receptors in regulation of prolactin gene expression in GH cells

Calf thymus DNA polymerase β and mammalian type C retroviral DNA polymerases are strongly inhibited by low concentrations (1–2mM) of inorganic phosphate (Pi). A detailed analysis of this phenomenon revealed that Pi-mediated inhibition: a) requires the presence of Mn²⁺ (Mg²⁺ neither supports nor relieves this inhibition; b) is strongly affected by the stoichiometric relationship between Mn²⁺ and Pi concentrations; c) is competitive with respect to deoxynucleoside triphosphate (dNTP) concentration, and d) increasing the concentration of substrate or non-substrate dNTPs in reaction mixtures raised the concentration of Mn²⁺ at which significant inhibition by a fixed concentration of Pi was first seen. These findings suggested that Mn²⁺, dNTPs, and Pi may interact in Pi-mediated inhibition. Thin-layer chromatographic analysis revealed the formation of an Mn-dNTP-Pi complex, while Mg²⁺ did not participate in such complex formation. We propose that it is this tripartite complex which is responsible for the Pi-mediated inhibition of sensitive DNA polymerases.     

Regulatory interaction between calmodulin and ATP on the red cell Ca2+ pump

The interactions between calmodulin, ATP and Ca²⁺ on the red cell Ca²⁺ pump have been studied in membranes stripped of native calmodulin or rebound with purified red cell calmodulin. Calmodulin stimulates the maximal rate of $\text{(Ca}{}^{\mathrm{2+}}\text{+ Mg}{}^{\mathrm{2+}}\text{)-ATPase}$ by 5–10-fold and the rate of Ca²⁺-dependent phosphorylation by at least 10-fold. In calmodulin-bound membranes ATP activates $\text{(}\text{Ca}{}^{\mathrm{2+}}\text{+ Mg}{}^{\mathrm{2+}}\text{)-ATPase}$ along a biphasic concentration curve ($\text{K}{}_{\mathrm{<mtext>m</mtext><mtext>1</mtext>}}\text{≈ 1.4 μ}\text{M}\text{, K}{}_{\mathrm{<mtext>m</mtext><mtext>2</mtext>}}\text{≈ 330 μ}\text{M}$), but in stripped membranes the curve is essentially hyperbolic ($\text{K}{}_{\mathrm{<mtext>m</mtext>}}\text{≈ 7 μ}\text{M}$). In calmodulin-bound membranes Ca²⁺ activates $\text{(}\text{Ca}{}^{\mathrm{2+}}\text{+ Mg}{}^{\mathrm{2+}}\text{)-ATPase}$ at low concentrations ($\text{K}{}_{\mathrm{<mtext>m</mtext>}}\text{< 0.28 μ}\text{M}$) in stripped membranes the apparent Ca²⁺ affinities are at least 10-fold lower.The results suggest that calmodulin (and perhaps ATP) affect a conformational equilibrium between E₂ and E₁ forms of the Ca²⁺ pump protein.     

窄等离子体吸收谱线宽度的纳米金锥用于光声成像

无损光声成像技术结合了纯光学成像高选择特性和纯超声成像中深穿透特性的优点,克服了光散射限制,实现了对活体深层组织的高分辨、高对比度成像。该成像技术对内源物质例如脱氧血红蛋白、含氧血红蛋白、黑色素、脂质等进行成像,提供了活体生物组织结构和功能信息,已经在生物医学领域表现出巨大的应用前景。然而,很多与病理过程相关的特征分子的光吸收能力较弱,在活体环境中难以被光声成像系统所识别,从而限制了光声成像技术的应用范围。基于功能纳米探针的光声成像-光声分子成像极大拓展光声成像的应用范围,可以在活体层面对病理过程进行分子水平的定性和定量研究,将为实现目标疾病的早期诊断提供强大的技术支持。本文发展在近红外具有窄吸收线宽(半高宽仅为60 nm)的纳米金锥作为新型的光声探针。通过选择不同径长比的纳米金锥,可以任意调节纳米金锥的吸收峰。通过调谐激光器的波长,可实现对不同吸收峰纳米金锥的选择性激发。纳米金锥将有可能用于多光谱光声成像,实现对不同靶标的目标分子探测。     

Polyamine transport in parasites: a potential target for new antiparasitic drug development

The metabolism of the naturally occurring polyamines-putrescine, spermidine and spermine-is a highly integrated system involving biosynthesis, uptake, degradation and interconversion. Metabolic differences in polyamine metabolism have long been considered to be a potential target to arrest proliferative processes ranging from cancer to microbial and parasitic diseases. Despite the early success of polyamine inhibitors such as alpha-difluoromethylornithine (DFMO) in treating the latter stages of African sleeping sickness, in which the central nervous system is affected, they proved to be ineffective in checking other major diseases caused by parasitic protozoa, such as Chagas' disease, leishmaniasis or malaria. In the use and design of new polyamine-based inhibitors, account must be taken of the presence of up-regulated polyamine transporters in the plasma membrane of the infectious agent that are able to circumvent the effect of the drug by providing the parasite with polyamines from the host. This review contains information on the polyamine requirements and molecular, biochemical and genetic characterization of different transport mechanisms in the parasitic agents responsible for a number of the deadly diseases that afflict underdeveloped and developing countries.     

Endogenous arachidonic acid metabolism by cultured arterial smooth muscle cells

Cultured aortic smooth muscle cells originated from healthy and atherosclerotic rabbits produce prostaglandins (namely prostacyclin) at a basal state. Prostaglandin secretion is dramatically reduced in atherosclerotic cells. This impairment was not correlated with any alteration of acyl hydrolase activities and probably involved a decrease of cyclooxygenase activities.