Desensitization of endothelial P2Y1 receptors by PKC-dependent mechanisms in pressurized rat small mesenteric arteries

Background and purpose:

Extracellular nucleotides play a crucial role in the regulation of vascular tone and blood flow. Stimulation of endothelial cell P2Y1 receptors evokes concentration-dependent full dilatation of resistance arteries. However, this GPCR can desensitize upon prolonged exposure to the agonist. Our aim was to determine the extent and nature of P2Y1 desensitization in isolated and pressurized rat small mesenteric arteries.

Experimental approach:

The non-hydrolyzable selective P2Y1 agonist ADPβS (3 µM) was perfused through the lumen of arteries pressurized to 70 mmHg. Changes in arterial diameter and endothelial cell [Ca²⁺]_i were obtained in the presence and absence of inhibitors of protein kinase C (PKC).

Key results:

ADPβS evoked rapid dilatation to the maximum arterial diameter but faded over time to a much-reduced plateau closer to 35% dilatation. This appeared to be due to desensitization of the P2Y1 receptor, as subsequent endothelium-dependent dilatation to acetylcholine (1 µM) remained unaffected. Luminal treatment with the PKC inhibitors BIS-I (1 µM) or BIS-VIII (1 µM) tended to augment concentration-dependent dilatation to ADPβS (0.1–3 µM) and prevented desensitization. Another PKC inhibitor, Gö 6976 (1 µM), was less effective in preventing desensitization. Measurements of endothelial cell [Ca²⁺]_i in pressurized arteries confirmed the P2Y1 receptor but not M₃ muscarinic receptor desensitization.

Conclusions and implications:

These data demonstrate for the first time the involvement of PKC in the desensitization of endothelial P2Y1 receptors in pressurized rat mesenteric arteries, which may have important implications in the control of blood flow by circulating nucleotides.     

Persistent effects of mifepristone (RU-486) on cortisol levels in bipolar disorder and schizophrenia

Recent pre-clinical and clinical studies have examined the potential use of anti-glucocorticoid drug augmentation - including glucocorticoid receptor (GR) antagonists - as a method of improving treatment response in severe psychiatric illness. However, the direct and persistent effects such drugs exert on the hypothalamic-pituitary-adrenal (HPA) axis are unclear. We examined afternoon cortisol levels in 39 patients (19 with bipolar disorder, 20 with schizophrenia) at baseline, following treatment with mifepristone (600mg/day for 7 days) or placebo and at +21 days. Following treatment with mifepristone (day +7) there was a significant increase in cortisol levels from baseline (mean change=60,434nmol/Lxmin, 95%CI=44,755-76,112; t=7.803, df=38, p<0.0001) which significantly decreased from this point by day +21 (mean change=-64,487nmol/Lxmin, 95%CI=-49,974 to -79,001; t=8.995, df=38, p<0.0001). Cortisol levels at day +21 were significantly lower than they were at baseline (mean change=-4054nmol/Lxmin, 95%CI=-456 to -7652; t=2.281, df=38, p=0.028). No significant changes occurred following placebo. These results provide preliminary evidence that subtle but significant reductions in HPA axis activity (measured by peripheral cortisol levels) are evident 14 days after cessation of treatment with the GR-antagonist mifepristone. This may in part underlie the putative therapeutic effects of such drugs.     

金藤清痹颗粒治疗急性痛风性关节炎的作用机制研究

目的 应用网络药理学分析金藤清痹颗粒治疗急性痛风性关节炎（acute gouty arthritis,AGA）的作用机制,并建立AGA大鼠模型进行验证。方法 在清热解毒、活血止痛治法指导下,通过TCMSP数据库搜集金藤清痹颗粒的活性成分及靶点,利用GeneCards、NCBI数据库等搜集AGA相关靶点,与金藤清痹颗粒作用靶点整合后,构建共有靶点蛋白质-蛋白质相互作用（protein-protein interaction,PPI）网络和“金藤清痹颗粒-中药-活性成分-靶点-AGA”网络,并进行基因本体（gene ontology,GO）功能及京都基因与基因组百科全书（Kyoto encyclopedia of genes and genomes,KEGG）通路富集分析。雄性SD大鼠随机分为空白组、模型组、秋水仙碱（0.3 mg/kg）组和金藤清痹颗粒低、中、高剂量（1.05、2.10、4.20 g/kg）组,每组6只,踝关节注射单钠尿酸盐（monosodium urate,MSU）晶体建立AGA大鼠模型。采用游标卡尺测量大鼠踝关节直径,计算踝关节肿胀度;采用全自动生化仪检测血清尿酸（serum uric acid,SUA）、C反应蛋白（C-reactive protein,CRP）水平;采用苏木素-伊红（HE）染色观察踝关节组织病理变化;采用qRT-PCR、ELISA和Western blotting检测踝关节组织及血清中关键靶点和信号通路的表达。结果 共检索到金藤清痹颗粒110种活性成分、212个作用靶点,272个AGA治疗靶点,共有靶点29个,关键靶点有白细胞介素-1β（interleukin-1β,IL-1β）、肿瘤坏死因子（tumor necrosis factor,TNF）及IL-6,涉及TNF信号通路、IL-17信号通路和NOD样受体信号通路等。大鼠踝关节注射MSU晶体后明显肿胀（P<0.01）,SUA及CRP显著升高（P<0.05、0.01）,滑膜组织增生明显、结构紊乱,有大量炎症细胞浸润,NOD样受体热蛋白结构域相关蛋白3（NOD-like receptor thermal protein domain associated protein 3,NLRP3）、NIMA相关蛋白激酶7（NIMA-related kinases 7,NEK7）、凋亡相关斑点样蛋白（apoptosis-associated speck-like protein containing a CARD,ASC）、半胱氨酸天冬氨酸蛋白酶-1（cystein-asparate protease-1,Caspase-1）、消皮素D（gasdermin D,GSDMD）、IL-18、IL-1β、IL-6及TNF-α表达水平明显升高（P<0.01）;秋水仙碱或金藤清痹颗粒治疗后,有效缓解踝关节肿胀（P<0.05、0.01）,SUA及CRP均显著降低（P<0.05、0.01）,关节滑膜增生、炎症细胞浸润均得到改善,同时显著抑制IL-1β、TNF-α及IL-6等靶点和NOD样受体信号通路的表达（P<0.05、0.01）。结论 金藤清痹颗粒对AGA大鼠具有明显的保护作用,其机制可能与抑制NOD样受体信号通路的异常激活,降低炎症因子水平,改善关节滑膜增生、炎症细胞浸润有关。     

The factor V B-domain provides two functions to facilitate thrombin cleavage and release of the light chain

Blood coagulation factors V and VIII are homologous proteins that have the domain organization A1-A2-B-A3-C1-C2. Upon thrombin activation, the B-domains of both molecules are released. Previous studies on factor VIII showed that the B-domain was not required for thrombin cleavage or activity. In contrast, deletion of the factor V B-domain (residues 709 to 1545) yielded a molecule with sevenfold reduced procoagulant activity that was not cleaved by thrombin. However, this factor V B- domain deletion molecule was activated by factor Xa, although the fold- activation was 85% that of wild-type factor V. Thrombin cleavage of factor V occurs initially after residue 709 and subsequently after residues 1018 and 1545. The requirement for thrombin cleavage within the B-domain at residue 1018 was evaluated by mutagenesis of Arg1018 to Ile. In the resultant R1018I mutant, the rate of thrombin activation and appearance of maximal cofactor activity was delayed and was consistent with delayed cleavage of the light chain at residue 1545. In contrast, the rate of factor Xa activation in the R1018I mutant was not altered. This finding suggests that thrombin cleavage at 1018 facilitates subsequent thrombin cleavage at 1545. Further mutagenesis was used to study the requirement for sequences within the factor V B- domain for thrombin cleavage at residue 1545. Whereas the factor V deletion molecule removing residues 709 to 1545 was not cleaved by thrombin, a smaller B-domain deletion molecule (residues 709 to 1476) containing an acidic amino acid-rich region (residues 1490 to 1520) was effectively cleaved by thrombin. These results show that residues 1476 to 1545, which contain an acidic amino acid-rich region, were required for thrombin cleavage of the light chain. Introduction of an acidic amino acid-rich region from factor VIII (residues 337 to 372) into the factor V 709 to 1545 deletion also restored thrombin cleavage of the light chain. In contrast, similar replacement with the acidic region from the factor VIII light chain (residues 1649 to 1689) was significantly less effective in promoting thrombin cleavage of the light chain. This finding suggests that the different acidic regions in factors V and VIII are not functionally equivalent in their interaction with thrombin.(ABSTRACT TRUNCATED AT 400 WORDS)     

The distinctive profile of risk factors of nasopharyngeal carcinoma in comparison with other head and neck cancer types

Background

Nasopharyngeal carcinoma (NPC) and other head and neck cancer (HNCA) types show a great epidemiological variation in different regions of the world. NPC has multifactorial etiology and many interacting risk factors are involved in NPC development mainly Epstein Barr virus (EBV). There is a need to scrutinize the complicated network of risk factors affecting NPC and how far they are different from that of other HNCA types.

Methods

122 HNCA patients and 100 control subjects were studied in the region of the Middle East. Three types of HNCA were involved in our study, NPC, carcinoma of larynx (CL), and hypopharyngeal carcinoma (HPC). The risk factors studied were the level of EBV serum IgG and IgA antibodies measured by ELISA, age, sex, smoking, alcohol intake, histology, and family history of the disease.

Results

EBV serum level of IgG and IgA antibodies was higher in NPC than CL, HPC, and control groups (p < 0.01). NPC was associated with lymphoepithelioma (LE) tumors, males, regular alcohol intake, and regular smoking while CL and HPC were not (p < 0.05). CL and HPC were associated with SCC tumors (p < 0.05). Furthermore, NPC, unlike CL and HPC groups, was not affected by the positive family history of HNCA (p > 0.05). The serum levels of EBV IgG and IgA antibodies were higher in LE tumors, regular smokers, younger patients, and negative family history groups of NPC patients than SCC tumors, non-regular smokers, older patients and positive family history groups respectively (p < 0.05) while this was not found in the regular alcoholics (p > 0.05).

Conclusion

It was concluded that risk factors of NPC deviate much from that of other HNCA. EBV, smoking, alcohol intake, LE tumors, male patient, and age > 54 years were hot risk factors of NPC while SCC and positive family history of the disease were not. Earlier incidence, smoking, LE tumors, and negative family history of the disease in NPC patients were associated much clearly with EBV. It is proposed that determining the correct risk factors of NPC is vital in assigning the correct risk groups of NPC which helps the early detection and screening of NPC.     

Campomelic syndrome. Difficulties in early differential diagnosis from other syndromes involving deformation of the long bones using echography

One case of "campomélique" dysplasia discovered by echography at 17 weeks is reported. The details of the syndrome are recalled. In this particular case, only the histology enabled the exact diagnosis to be made. The distinction between "syndrome campomélique" and other syndromes involving deformation of long bones (imperfect osteogenesis of the foetal type and isolated curvature of the tibia) is not easy during early pregnancy using echography alone. At a later stage, the signs and symptoms become more distinct and an exact diagnosis is probably easier.