PGE2 inhibits basolateral 50 pS potassium channels in the thick ascending limb of the rat kidney

To study the inhibition of the inwardly rectifying basolateral 50 pS potassium channels by PGE(2) we performed patch-clamp studies on the basolateral membrane of the rat kidney thick ascending limb. PGE(2)'s effect was mimicked by the selective EP1- and EP3-receptor agonist, sulprostone, but was prevented by inhibiting protein kinase-C with calphostin-C. The mitogen-activated protein kinase inhibitor PD98059 (ERK) or SB203580 (p38) increased basal channel activity; however, while neither alone prevented the inhibitory effect of PGE(2), but using both of them together completely abolished PGE(2)'s effect on channel activity. Treatment with PGE(2) stimulated phosphorylation of both p38 and ERK in primary cultures of medullary thick ascending limb cells. The PGE(2)-mediated mitogen-activated protein kinase activation was not affected by indomethacin, but was completely blocked by calphostin-C. These studies show that inhibition of basolateral 50 pS potassium channels by PGE(2) is mediated by protein kinase-C, which in turn stimulates mitogen-activated protein kinases in the thick ascending limb of the rat kidney.     

In vitro human skin model to evaluate water permeability and determine wound dressings' occlusivity

Wound dressings' occlusivity is directly correlated with water permeability and may affect wound healing. This study evaluated the wound dressings' occlusivity in comparison to their ability to retain water in an in vitro human skin model. Human cadaver skin was stretched over fully filled vials of physiological saline and banded. After 30 minutes, during which equilibrium was established, baseline values for transepidermal water loss (TEWL) were measured. Then an occlusive film was placed over one skin, a semi-occlusive dressing over another and finally 100 microL of a 5% copolymer solution over the third piece of skin, which was then allowed to aerate until it formed a thin membrane. One skin sample was left fully exposed to the air, serving as a blank control. After 30 minutes post-treatment, the TEWL was re-measured for all the samples. TEWL values showed the occlusive film was the most water-impermeable, allowing only a mean of 1.6 g/m(2) hours of water to pass through and thus also showing a significant difference (p < 0.05) in comparison to the blank (untreated) control. Furthermore, the semi-occlusive membrane decreased TEWL but not significantly, whereas the film former appeared to have no effect. We found no significant decrease in TEWL in the semi-occlusive membrane and even in the film former. This in vitro model provides a fast and economical method of screening the effect of occlusivity in wound dressings.     

Protective effects of insulin on polychlorinated biphenyls-induced disruption of actin cytoskeleton in hippocampal neurons

Insulin receptors are widely distributed in the brain, and insulin improves learning and memory in some brain injury. Insulin elevates LIM kinase 1 (LIMK-1) activity and induces actin polymerization in some cells, while actin cytoskeleton dynamics mediated via LIMK-1/cofilin signal pathway is considered important to learning and memory formation. Our previous studies have shown that polychlorinated biphenyls (PCBs) disrupt the actin cytoskeleton by inhibiting LIMK-1/cofilin signaling pathway in the cultured hippocampal neurons. To determine potential neuronal protective effects by insulin, we administered insulin to the cultured hippocampal neurons after exposure to PCBs mixture Aroclor 1254 (A 1254). We found that insulin antagonized a loss of filamentous actin and the cytotoxicity induced by A 1254. Similarly, insulin restored the decrease of LIMK-1 and cofilin phosphorylation induced by A 1254. We concluded that insulin could protect neurons, probably partly by ameliorating filamentous actin cytoskeleton disruption mediated via the activation of LIMK-1/cofilin signal pathway in cultured hippocampal neurons after exposure to A 1254. The above protective effects in hippocampal neuron may have important implications in the treatment of PCBs-induced neurotoxicity and the mechanism by which insulin improves learning and memory. (c) 2007 Wiley Periodicals, Inc. Environ Toxicol 22: 152-158, 2007.     

Clonidine attenuates morphine withdrawal and subsequent drug sensitization in rhesus monkeys

AIM: Clonidine is an alpha2 adrenoceptor agonist that is frequently used to reduce withdrawal symptoms during opioid detoxification in humans. The long-term effects of clonidine on withdrawal symptoms and its effects on subsequent drug exposure have not been thoroughly documented. The aim of the study was to determine if clonidine administered during morphine withdrawal in rhesus monkeys produces long-lasting effects on withdrawal symptoms and alters the effects of subsequently taken drugs of abuse. METHODS: Adult male rhesus monkeys were treated with increasing doses of morphine for 90 d to induce opiate (narcotic) dependence. The immediate and long-lasting effects of 1 week's administration of clonidine were measured via the recording of morphine withdrawal signs and the subsequent effects of challenge injections of morphine or cocaine. RESULTS: Monkeys chronically treated with morphine displayed withdrawal signs that lasted 2 weeks after cessation of morphine administration and displayed sensitized responses to subsequent morphine and cocaine injections. Clonidine significantly reduced certain morphine withdrawal signs and overall withdrawal score, but these effects did not persist upon cessation of clonidine treatment. Sensitization to the effects of morphine and cocaine were significantly reduced in monkeys previously treated with clonidine. CONCLUSION: Our results suggest that in addition to its short-term alleviating effect on morphine withdrawal signs, clonidine may reduce subsequent effects of drugs of abuse after prolonged abstinence.     

低频经颅磁刺激对匹罗卡品致痫大鼠海马区神经肽Y表达及细胞凋亡的影响

目的观察低频经颅磁刺激对匹罗卡品致痫大鼠海马各区神经肽Y（NPY）表达和神经细胞凋亡的影响。方法雄性SD大鼠30只,随机分为对照组、低频经颅磁刺激干预组。干预组给予低频经颅磁刺激,对照组给予假性刺激后,注射匹罗卡品建立癫痫模型。行海马HE染色、NPY免疫组织化学染色观察和细胞凋亡观察。结果干预组海马结构损害较对照组明显减轻。对照组各时间点海马各区NPY阳性细胞数量明显高于低频经颅磁刺激干预组,而凋亡细胞数量明显高于低频经颅磁刺激干预组,差异有统计学意义。结论低频经颅磁刺激可影响海马各区NPY表达,降低海马区神经损害,具有显著的抗痫作用。NPY表达与癫痫之间关系紧密,可能存在抗痫和神经保护作用。     

Conformational templates for rational drug design: flexibility of cyclo(D-Pro1-Ala2-Ala3-Ala4-Ala5) in DMSO solution

Long MD simulations (100 ns) for the important model cyclopentapeptide cyclo(D-Pro1-Ala2-Ala3-Ala4-Ala5) were performed in explicit DMSO solution using both OPLS-AA and AMBER03 force fields. Simulations revealed conformational transitions between two main conformers, a predominant one (population 93-99%) and a minor conformer (population 0.4-6.7%). These results are in excellent agreement with 20 experimental proton-proton distances estimated for this cyclopentapeptide. The previously discussed gamma-turn-like conformation for Ala4 was present only in a minor conformer.     

Myeloid cell leukemia-1 inversely correlates with glycogen synthase kinase-3beta activity and associates with poor prognosis in human breast cancer

Myeloid cell leukemia-1 (Mcl-1), an antiapoptotic Bcl-2 family member, is overexpressed in many types of human cancer and associates with cell immortalization, malignant transformation, and chemoresistance. Glycogen synthase kinase-3beta (GSK-3beta), a key component of the Wnt signaling pathway, is involved in multiple physiologic processes such as protein synthesis, tumorigenesis, and apoptosis. Here, we report that expression of Mcl-1 was correlated with phosphorylated GSK-3beta (p-GSK-3beta) at Ser(9) (an inactivated form of GSK-3beta) in multiple cancer cell lines and primary human cancer samples. In addition, Mcl-1 was strikingly linked with poor prognosis of human breast cancer, in which the high level of Mcl-1 was related to high tumor grade and poor survival of breast cancer patients. Furthermore, we found that activation of GSK-3beta could down-regulate Mcl-1 and was required for proteasome-mediated Mcl-1 degradation. Under some physiologic conditions, such as UV irradiation, anticancer drug treatment, and inhibition of growth factor pathways, Mcl-1 was down-regulated through activation of GSK-3beta. Our results indicate that Mcl-1 stabilization by GSK-3beta inactivation could be involved in tumorigenesis and serve as a useful prognostic marker for human breast cancer.     

Common non-synonymous polymorphisms in the BRCA1 Associated RING Domain (BARD1) gene are associated with breast cancer susceptibility: a case-control analysis

The BRCA1 Associated RING Domain (BARD1) gene has been identified as a high penetrance gene for breast cancer, whose germline and somatic mutations were reported in both non-BRCA1/2 hereditary site-specific and sporadic breast cancer cases. BARD1 plays a crucial role in tumor repression, along with its heterodimeric partner BRCA1. In the current study, we tested the hypothesis that common non-synonymous polymorphisms in BARD1 are associated with breast cancer susceptibility in a case-control study of 507 patients with incident breast cancer and 539 frequency-matched cancer-free controls in Chinese women. We genotyped all three common (minor allele frequency (MAF)>0.10) non-synonymous polymorphisms (Pro24Ser, Arg378Ser, and Val507Met) in BARD1. We found that the BARD1 Pro24Ser variant genotypes (24Pro/Ser and 24Ser/Ser) and Arg378Ser variant homozygote 378Ser/Ser were associated with a significantly decreased breast cancer risk, compared with their wild-type homozygotes, respectively. Furthermore, a significant locus-locus interaction was evident between Pro24Ser and Arg378Ser (P(int )= 0.032). Among the 378Ser variant allele carriers, the 24Pro/Pro wild-type homozygote was associated with a significantly increased breast cancer risk (adjusted OR=1.81, 95% CI=1.11-2.95), but the subjects having 24Pro/Ser or Ser/Ser variant genotypes had a significantly decreased risk (adjusted OR=0.74, 95% CI=0.56-0.99). In stratified analysis, this locus-locus interaction was more evident among subjects without family cancer history, those with positive estrogen receptor (ER) and individuals with negative progesterone receptor (PR). These findings indicate that the potentially functional polymorphisms Pro24Ser and Arg378Ser in BARD1 may jointly contribute to the susceptibility of breast cancer.     

痰热清治疗COPD急性加重期的疗效及对血清C反应蛋白和IL-10的影响

目的探讨痰热清配合常规治疗对慢性阻塞性肺疾病急性加重期（AECOPD）患者血清CRP及IL-10表达的影响,并观察临床疗效。方法将90例AECOPD患者随机分为治疗组与对照组,各45例,均予常规治疗,治疗组加用痰热清静滴,疗程为10d。两组患者治疗前后测定血清CRP、IL-10含量。结果治疗组显效率较对照组明显提高,差异有显著性（P〈0．05）。两组患者治疗后CRP表现出下降趋势。其中治疗组CRP下降更快：治疗组治疗后血清IL-10的含量明显低于对照组。结论在常规治疗的基础上联用痰热清治疗AECOPD能明显提高临床疗效;痰热清可阻止体内的炎症反应,对COPD急性加重期的治疗具有临床意义。