Gold Nanoparticle Conjugation Enhances the Antiacanthamoebic Effects of Chlorhexidine

Acanthamoeba keratitis is a serious infection with blinding consequences and often associated with contact lens wear. Early diagnosis, followed by aggressive topical application of drugs, is a prerequisite in successful treatment, but even then prognosis remains poor. Several drugs have shown promise, including chlorhexidine gluconate; however, host cell toxicity at physiologically relevant concentrations remains a challenge. Nanoparticles, subcolloidal structures ranging in size from 10 to 100 nm, are effective drug carriers for enhancing drug potency. The overall aim of the present study was to determine whether conjugation with gold nanoparticles enhances the antiacanthamoebic potential of chlorhexidine. Gold-conjugated chlorhexidine nanoparticles were synthesized. Briefly, gold solution was mixed with chlorhexidine and reduced by adding sodium borohydride, resulting in an intense deep red color, indicative of colloidal gold-conjugated chlorhexidine nanoparticles. The synthesis was confirmed using UV-visible spectrophotometry that shows a plasmon resonance peak of 500 to 550 nm, indicative of gold nanoparticles. Further characterization using matrix-assisted laser desorption ionization-mass spectrometry showed a gold-conjugated chlorhexidine complex at m/z 699 ranging in size from 20 to 100 nm, as determined using atomic force microscopy. To determine the amoebicidal and amoebistatic effects, amoebae were incubated with gold-conjugated chlorhexidine nanoparticles. For controls, amoebae also were incubated with gold and silver nanoparticles alone, chlorhexidine alone, neomycin-conjugated nanoparticles, and neomycin alone. The findings showed that gold-conjugated chlorhexidine nanoparticles exhibited significant amoebicidal and amoebistatic effects at 5 μM. Amoebicidal effects were observed by parasite viability testing using a Trypan blue exclusion assay and flow-cytometric analysis using propidium iodide, while amoebistatic effects were observed using growth assays. In contrast, chlorhexidine alone, at a similar concentration, showed limited effects. Notably, neomycin alone or conjugated with nanoparticles did not show amoebicidal or amoebistatic effects. Pretreatment of A. castellanii with gold-conjugated chlorhexidine nanoparticles reduced amoeba-mediated host cell cytotoxicity from 90% to 40% at 5 μM. In contrast, chlorhexidine alone, at similar concentrations, had no protective effects for the host cells. Similarly, amoebae treated with neomycin alone or neomycin-conjugated nanoparticles showed no protective effects. Overall, these findings suggest that gold-conjugated chlorhexidine nanoparticles hold promise in the improved treatment of A. castellanii keratitis.     

Recent evolution of a novel begomovirus causing tomato leaf curl disease in the Al-Batinah region of Oman

For last two decades, begomoviruses (family Geminiviridae) have been a major constraint for tomato production in Oman, particularly in the Al-Batinah region, the major agricultural area of Oman. Farms in the Al-Batinah region were surveyed during January-March and November-December in 2012 and January-February in 2013. Leaf samples of tomato plants showing typical leaf curl disease symptoms were collected and analyzed for begomoviruses. Out of fifteen begomovirus clones sequenced, seven were shown to be tomato yellow leaf curl virus strain Oman (TYLCV-OM); three, chili leaf curl virus strain Oman (ChLCV-OM); and one, tomato leaf curl Oman virus (ToLCOMV) – viruses that have previously been shown to occur in Oman. Four sequences were shown to have relatively low percent identity values to known begomoviruses, with the highest (86 %) to isolates of pepper leaf curl Lahore virus, indicating that these should be included in a new species, for which the name “Tomato leaf curl Al Batinah virus” (ToLCABV) is proposed. Although the betasatellite tomato leaf curl betasatellite (ToLCB; 7 full-length sequences isolated) was identified with some isolates of ChLCV-OM, TYLCV-OM and ToLCOMV, it was not identified in association with any of the ToLCABV isolates. Analysis of the sequences of the TYLCV-OM and ToLCOMV isolates characterized here did not show them to differ significantly from previously characterized isolates of these viruses. The three isolates of ChLCV-OM characterized were shown to have a recombination pattern distinct from earlier characterized isolates. ToLCABV was shown to have resulted from recombination between ChLCV-OM and ToLCOMV. A clone of ToLCABV was infectious by Agrobacterium-mediated inoculation to Nicotiana benthamiana and tomato, inducing symptoms typical of those seen in tomato in the field. Additionally, ToLCABV was shown to be able to interact in planta with ToLCB, resulting in a change in symptom phenotype, although the betasatellite did not appear to affect viral DNA levels.     

The Heartfile Lodhran CVD prevention project--end of project evaluation

Mainstream preventive interventions often fail to reach poor populations with a high risk of cardiovascular diseases (CVDs) in Pakistan. A community-based CVD primary prevention project aimed at developing approaches to reduce risk factors in such populations was established by Heartfile in collaboration with the National Rural Support Program in the district of Lodhran. The project implemented a range of activities integrated with existing social and health service mechanisms during a three year intervention period 2000/01-03/04. These were targeted in 4 key settings: community health education, mass media interventions, training of health professionals and health education through Lady Health Workers. The project received support from the Department for International Development, U.K. At the community level, a pre-test-post-test quasi-experimental design was used for examining project outcomes related to the community component of the intervention. Pre and post-intervention (training) evaluations were conducted involving all health care providers in randomly selected workshops in order to determine baseline levels of knowledge and the impact of training on knowledge level. In order to assess practices of physician and non-physician health care providers patient interviews, with control comparisons were conducted at each health care facility. Significant positive changes were observed in knowledge levels at a community level in the district of intervention compared with baseline knowledge levels particularly in relation to a heart healthy diet, beneficial level of physical activity, the causes of high blood pressure and heart attack and the effects of high blood pressure and active and passive smoking on health. Significant changes in behaviors at a practice level were not shown in the district of intervention. However the project played a critical role in spurring national action for the prevention and control of non-communicable diseases and introducing sustainable public health interventions for poor communities in Pakistan.     

p38MAPK对轻度热应激大鼠脾脏巨噬细胞免疫功能的影响

目的: 探讨p38MAPK在Bip蛋白介导的体外轻度热应激大鼠巨噬细胞功能改变中的信号作用.方法: p38MAPK抑制剂预处理大鼠脾脏巨噬细胞,将细胞置于41℃恒温箱中,使细胞轻度热应激,1 h后恢复到37℃(抑制组),以未应激(对照组)和41℃热应激1 h后60 min巨噬细胞(应激组)为对照,分别检测3组巨噬细胞吞噬、杀伤、趋化功能,同时检测p38MAPK蛋白和Bip蛋白的表达.结果: p38MAPK抑制剂预处理大鼠脾脏巨噬细胞,与应激组比较,轻度热应激后巨噬细胞吞噬、趋化和杀伤活性明显降低(0.17±0.01 vs 0.74±0.03,33.32±3.55 vs 82.07±5.17,24.20%±2.39% vs 60.80%±4.02%,均P<0.01);应激组p38MAPK蛋白表达明显上调,p38MAPK抑制剂预处理后,抑制组p38 MAPK蛋白表达受到抑制,与应激组比较差异有显著性(p38/β-actin: 2.863±0.794 vs 4.752±1.386,P<0.01);Bip蛋白的表达(Bip/β-act in)也因p38MAPK抑制剂预处理而由应激组的1.270±0.535降至抑制组的1.028±1.061( P<0.05).结论: p38MAPK抑制剂可显著抑制轻度热应激大鼠巨噬细胞吞噬、趋化和杀伤功能以及p38MAPK和Bip蛋白的表达.