Induction of P‐glycoprotein and Bcrp at the rat blood–brain barrier following a subchronic morphine treatment is mediated through NMDA/COX‐2 activation

Subchronic morphine treatment induces P‐glycoprotein (P‐gp) up‐regulation at the blood–brain barrier. This study investigates the rate and extent to which P‐gp and breast cancer‐resistance protein (Bcrp) increase at the rat blood–brain barrier following subchronic morphine treatment. Rats were given increasing doses of morphine (10–40 mg/kg) or saline i.p. twice daily for 5 days. The brain cortex large vessels and microvessels were then mechanical isolated 6, 9, 12, 24, and 36 h after the last injection. The gene and protein expression of P‐gp and Bcrp in morphine‐treated and control rats were compared by qRT‐PCR and western blotting. The levels of Mdr1a and Bcrp mRNAs were not significantly modified 6 h post morphine, but the Mdr1a mRNA increased 1.4‐fold and Bcrp mRNA 2.4‐fold at 24 h. P‐gp and Bcrp protein expression in brain microvessels was unchanged 6 h post morphine and increased 1.5‐fold at 24 h. This effect was more pronounced in large vessels than in microvessels. However, extracellular morphine concentrations of 0.01–10 μM did not modify the expressions of the MDR1 and BCRP genes in hCMEC/D3 human endothelial brain cells in vitro. MK‐801 (NMDA antagonist) and meloxicam (cyclo‐oxygenase‐2 inhibitor) given after morphine treatment completely blocked P‐gp and Bcrp up‐regulation. Interestingly, misoprostol and iloprost, two well‐known agonists of prostaglandin E2 receptors induced both MDR1 and BCRP mRNA levels in hCMEC/D3. Thus, morphine does not directly stimulate P‐gp and Bcrp expression by the brain endothelium, but glutamate released during morphine withdrawal may do so by activating the NMDA/cyclo‐oxygenase‐2 cascade.     

Epithelial Fluid Transport: Protruding Macromolecules and Space Charges Can Bring about Electro-Osmotic Coupling at the Tight Junctions

The purpose of the present work is to investigate whether the idea of epithelial fluid transport based on electro-osmotic coupling at the level of the leaky tight junction (TJ) can be further supported by a plausible theoretical model. We develop a model for fluid transport across epithelial layers based on electro-osmotic coupling at leaky tight junctions (TJ) possessing protruding macromolecules and fixed electrical charges. The model embodies systems of electro-hydrodynamic equations for the intercellular pathway, namely the Brinkman and the Poisson-Boltzmann differential equations applied to the TJ. We obtain analytical solutions for a system of these two equations, and are able to derive expressions for the fluid velocity profile and the electrostatic potential. We illustrate the model by employing geometrical parameters and experimental data from the corneal endothelium, for which we have previously reported evidence for a central role for electro-osmosis in translayer fluid transport. Our results suggest that electro-osmotic coupling at the TJ can account for fluid transport by the corneal endothelium. We conclude that electro-osmotic coupling at the tight junctions could represent one of the basic mechanisms driving fluid transport across some leaky epithelia, a process that remains unexplained.     

异型增生上皮和口腔鳞癌组织EGFR和PCNA表达意义及相关性研究

采用免疫组化S－P法研究表皮生长因子受体（EGFR）、增殖核抗原（PCNA）在口腔粘膜上皮异型增生及口腔鳞癌组织中的表达意义及其相互关系。结果表明,EGFR及PCNA的正常口腔粘膜上皮为阴性或仅在上皮基底层有少量阳性表达。上皮异型增生时,随病变程度加重,阳性表达呈递增趋势（P＜0.01）,至重度异型增生时,PCNA表达与鳞癌无显性差异（P＞0.05）,EGFR表达甚至超过高分化鳞癌。口腔鳞癌组织随分化程度降低,阳性表达率相应增加（P＜0.01）。EGFR表达与PCNA表达有明显相关性（P＜0.01）。EGFR和PCNA可作为评估和监测口腔粘膜上皮恶变潜能,判断口腔鳞癌恶性度的有用标记物。     

The advantage of long-distance clonal spreading in highly disturbed habitats

Summary Classical theory states that cover of annual plants should increase relative to perennials as disturbance frequency increases. However, it has been suggested that long-distance clonal spreading can allow some perennial plants to survive in highly disturbed areas by quickly spreading into disturbed patches. To evaluate these hypotheses, we analysed data of plant distributions in two different ecosystems, a barrier island and a short-grass steppe. The disturbances studied were sand deposition during storms (overwash) on the barrier island and grazing by cattle in the short-grass steppe. In each case the disturbance frequency varied over the ecosystem; we categorized different areas in terms of their disturbance frequencies. All plant species in each area were categorized as one of four plant life forms (1) annual or biennial, (2) herbaceous perennial without long-distance clonal spreading (3) herbaceous perennial with long-distance clonal spreading (i.e guerilla form) and (4) woody plant. Percentage cover of each plant life form in each disturbance frequency category was calculated. In both ecosystems, (1) there was an increase in the relative cover of annuals as one moved from areas of low to moderate disturbance frequencies, but then a decrease in cover of annuals as one moved into the areas of highest disturbance frequency and (2) the guerilla forms showed the greatest relative increase in cover from moderately to highly disturbed areas. The combination of two factors can explain this pattern: (1) long-distance clonal spreading effectively reduces the time to colonization of recently disturbed sites and (2) effects of the disturbances in these two systems are probably more severe for seeds than for stems. We illustrate these effects using a spatially explicit simulation model of the population dynamics of plants in a disturbed landscape.     

Heat shock proteins: A dual carrier-adjuvant for an anti-drug vaccine against heroin

Heroin is a highly abused opioid that has reached epidemic status within the United States. Yet, existing therapies to treat addiction are inadequate and frequently result into rates of high recidivism. Vaccination against heroin offers a promising alternative therapeutic option but requires further development to enhance the vaccine’s performance. Hsp70 is a conserved protein with known immunomodulatory properties and is considered an excellent immunodominant antigen. Within an antidrug vaccine context, we envisioned Hsp70 as a potential dual carrier-adjuvant, wherein immunogenicity would be increased by co-localization of adjuvant and antigenic drug hapten. Recombinant Mycobacterium tuberculosis Hsp70 was appended with heroin haptens and the resulting immunoconjugate granted anti-heroin antibody production and blunted heroin-induced antinociception. Moreover, Hsp70 as a carrier protein surpassed our benchmark Her-KLH cocktail through antibody-mediated blockade of 6-acetylmorphine, the main mediator of heroin’s psychoactivity. The work presents a new avenue for exploration in the use of hapten-Hsp70 conjugates to elicit anti-drug immune responses.     

Naturally prion resistant mammals: A utopia?

Each known abnormal prion protein (PrP^Sc) is considered to have a specific range and therefore the ability to infect some species and not others. Consequently, some species have been assumed to be prion disease resistant as no successful natural or experimental challenge infections have been reported. This assumption suggested that, independent of the virulence of the PrP^Sc strain, normal prion protein (PrP^C) from these ‘resistant’ species could not be induced to misfold. Numerous in vitro and in vivo studies trying to corroborate the unique properties of PrP^Sc have been undertaken. The results presented in the article “Rabbits are not resistant to prion infection” demonstrated that normal rabbit PrP^C, which was considered to be resistant to prion disease, can be misfolded to PrP^Sc and subsequently used to infect and transmit a standard prion disease to leporids. Using the concept of species resistance to prion disease, we will discuss the mistake of attributing species specific prion disease resistance based purely on the absence of natural cases and incomplete in vivo challenges. The BSE epidemic was partially due to an underestimation of species barriers. To repeat this error would be unacceptable, especially if present knowledge and techniques can show a theoretical risk. Now that the myth of prion disease resistance has been refuted it is time to re-evaluate, using the new powerful tools available in modern prion laboratories, whether any other species could be at risk.     

Enhanced Expression of an Endothelin ETA Receptor in Capillaries from Human Glioblastoma: A Quantitative Receptor Autoradiographic Analysis Using a Radioluminographic Imaging Plate System

Abstract: We identified and characterized ¹²⁵I-endothelin-1 (¹²⁵I-ET-1) binding sites in tumor capillaries isolated from human glioblastomas, using the quantitative receptor autoradiographic technique with pellet sections. Quantification was done using the computerized radioluminographic imaging plate system. High-affinity ET receptors were localized in capillaries from glioblastomas and the surrounding brain tissues (K_D = 4.7 ± 1.0 × 10^?10 and 1.6 ± 0.3 × 10^?10M, respectively; B_max = 161 ± 38 and 140 ± 37 fmol/mg, respectively; mean ± SEM, n = 5). BQ-123, a selective antagonist for the ET_A receptor, potently competed for ¹²⁵I-ET-1 binding to sections of the microvessels with IC₅₀ values of 5.1 ± 0.3 and 5.1 ± 1.5 nM, and 10^?6M BQ-123 displaced 84 and 58% of ET binding to capillaries from tumors and brains, respectively. In addition, competition curves obtained in the presence of increasing concentrations of ET-3 showed two components (IC₅₀ = 5.7 ± 2.5 × 10^?10 and 1.4 ± 0.2 × 10^?6M for tumor microvessels, 1.8 ± 0.6 × 10^?10 and 1.1 ± 0.3 × 10^?6M for brain microvessels, respectively). Our results indicate that (a) the method we used is simple and highly sensitive for detecting and characterizing various receptors in tumor capillaries, especially in the case of a sparse specimen, and (b) capillaries in glioblastomas express specific high-affinity ET binding sites, candidates for biologically active ET receptors, which predominantly belong to the ET_A subtype.     

Bovine colostrum promoted ileal health in newborn lambs at 24 h after birth: insight from intestinal morphology and innate immunity

The contribution of colostrum to passive immunity transfer and intestinal protection in newborn ruminants is well known; however, it is currently unclear how colostrum intake affects intestinal innate immunity. We investigated the effects of bovine colostrum intake on ileal morphology, expression of genes involved in intestinal innate immunity, and serum concentrations of inflammatory cytokines in newborn lambs. Twenty-seven newborn male Hu lambs were used, of which 18 were bottle-fed either bovine colostrum (C24h; n = 9) or bovine mature milk (M24h; n = 9) within the first 2 h after birth at an intake of approximately 8% of BW; the remaining nine lambs did not receive any feeding (N24h). Blood and ileal tissue samples were collected after the lambs were slaughtered at 24 h after birth. Ileal villus height and villus height-to-crypt depth ratio were significantly higher in C24h than those in N24h and M24h lambs (P < 0.01). Messenger RNA (mRNA) abundance of toll-like receptor (TLR)-2, TLR3, TLR4, TLR6, TLR7, TLR8 and tumour necrosis factor alpha in the ileum was lower in C24h than that in N24h lambs (P < 0.05). Moreover, C24h lambs had a lower TLR3 mRNA abundance (P < 0.01) and a trend of lower TLR6 (P = 0.06) and interleukin 1 beta (P = 0.08) expression compared with those in M24h lambs. We also observed strong positive correlations of tumour necrosis factor alpha expression with that of TLR2 (r = 0.71; P < 0.001), TLR4 (r = 0.88; P < 0.001) and TLR8 (r = 0.83; P < 0.001). Interestingly, the expression of barrier-related molecules, including mucin-13, lysozyme, claudin (CLDN)-1, CLDN2, CLDN4, CLDN7, CLDN12, occludin, zonula occluden-1 and junctional adhesion molecule-1, was consistently lower in C24h lambs than that in N24h and M24h lambs (P < 0.05). These results indicated that the beneficial roles of colostrum intake on intestinal protection in newborn lambs were associated with low TLR expression, which was reflected by improved intestinal development and reduced inflammatory response. Further studies using fluorescence in situ hybridisation and immunohistochemical methods are needed to further explore the mechanisms underlying the lower expression of intestinal barrier-related molecules due to colostrum feeding.     

单增李斯特菌感染胎盘相关毒力因子的研究进展

单核细胞增生李斯特氏菌(Listeria monocytogenes,LM)是一种可引起李斯特菌病的食源性致病菌。由于妊娠相关免疫缺陷和LM对非吞噬细胞独特的细胞内感染能力,孕妇是LM的主要目标人群。LM可穿过胎盘屏障,对胎儿造成重大伤害,包括早产、流产甚至死产。胎盘特异性毒力因子的作用对LM感染期间穿过胎盘屏障并感染胎儿尤为重要。文中介绍了国内外近年在孕妇中发生LM感染的事件,详细讨论了LM垂直传播以及在胎盘定殖机制方面的研究进展,着重讨论并分析了LM与感染胎盘相关毒力因子的最新发现,以期为今后防控LM的胎盘感染并保障食品安全提供参考。