Long-Lasting Immune Protection and Other Epidemiological Findings after Chikungunya Emergence in a Cambodian Rural Community,April 2012

The East/Central/South African genotype of Chikungunya virus with the E1-A226V mutation emerged in 2011 in Cambodia and spread in 2012. An outbreak of 190 cases was documented in Trapeang Roka, a rural village. We surveyed 425 village residents within 3–4 weeks after the outbreak, and determined the sensitivity and specificity of case definitions and factors associated with infection by CHIKV. Self-reported clinical presentation consisted mostly of fever, rash and arthralgia. The presence of all three clinical signs or symptoms was identified as the most sensitive (67%) and specific (84%) self-reported diagnostic clinical indicator compared to biological confirmation by MAC-ELISA or RT-PCR used as a reference. Having an indoor occupation was associated with lower odds of infection compared with people who remained at home (adjOR 0.32, 95%CI 0.12–0.82). In contrast with findings from outbreaks in other settings, persons aged above 40 years were less at risk of CHIKV infection, likely reflecting immune protection acquired when Chikungunya circulated in Cambodia before the Khmer Rouge regime in 1975. In view of the very particular history of Cambodia, our epidemiological data from Trapeang Roka are the first to support the persistence of CHIKV antibodies over a period of 40 years.     

Nimesulide-induced hepatic mitochondrial injury in heterozygous Sod2(+/-) mice

Nimesulide, a preferential COX-2 inhibitor, has been associated with rare idiosyncratic hepatotoxicity. The underlying mechanisms of liver injury are unknown, but experimental evidence has identified oxidative stress as a potential hazard and mitochondria as a target. The aim of this study was to explore whether genetic mitochondrial abnormalities, resulting in impaired mitochondrial function and mildly increased oxidative stress, might sensitize mice to the hepatic adverse effects of nimesulide. We used heterozygous superoxide dismutase 2 (Sod2(+/-)) mice as a model, as these mice develop clinically silent mitochondrial stress but otherwise appear normal. Nimesulide was administered for 4 weeks (10 mg/kg, ip, bid), at a dose equivalent to human therapeutic dosage. We found that the drug potentiated hepatic mitochondrial oxidative injury (decreased aconitase activity, increased protein carbonyls) in Sod2(+/-), but not wild-type, mice. Furthermore, the nimesulide-treated mutant mice exhibited increased hepatic cytosolic levels of cytochrome c and caspase-3 activity, as well as increased numbers of apoptotic hepatocytes. Finally, nimesulide in vitro caused a concentration-dependent net increase in superoxide anion in mitochondria from Sod2(+/-), but not Sod2(+/+) mice. In conclusion, repeated administration of nimesulide can superimpose an oxidant stress, potentiate mitochondrial damage, and activate proapoptotic factors in mice with genetically compromised mitochondrial function.     

Flux boundary measurements for the study of tree stability

The shear strength of soil is an important parameter that affects tree stability and can vary depending on the magnitude of the soil’s negative pore-water pressure (matric suction). The surface flux boundary condition affects the matric suction of soil, and therefore is important for tree stability. Field measurements were performed around a roadside tree for 2 years. The instrumentation results show that the matric suction in the soil fluctuated between 0 and 35 kPa. Matric suction changes in the soil could lead to a decrease in the tree resistive moment of up to 80 %.     

A high-performance liquid chromatography method for the quantification of cysmethynil,an inhibitor of isoprenylcysteine carboxylmethyl transferase,in mouse plasma

Cysmethynil, a newly identified small molecule inhibitor of isoprenylcysteine carboxylmethyl transferase (Icmt) is involved in the post-translational modification of CaaX proteins. Cysmethynil causes cell death in many human cancer cells in vitro, and inhibits tumor growth in the xenograft mouse model in vivo. A HPLC method for the quantification of cysmethynil in mouse plasma was developed and validated. The lower limit of quantification of this method was 0.01 μg/ml. Inter- and intra-day variability ranged from 0.38–8.5% and accuracy was between 86% and 98%. This sensitive method was used to quantify cysmethynil in plasma of mice after intraperitoneal dosing for preliminary pharmacokinetic studies.     

Muc1 Limits Helicobacter felis Binding to Gastric Epithelial Cells But Does not Limit Colonization and Gastric Pathology Following Infection

Background: The mucin Muc1 is constitutively expressed by the gastric mucosa and is likely the first point of direct contact between the host stomach and the adherent pathogens. The expression of Muc1 has been shown to limit colonization of mice by Helicobacter pylori, known to adhere to the gastric epithelium, as well as associated pathology. However, the potential role of this mucin against nonadherent Helicobacter has not been previously studied. We therefore examined the importance of Muc1 on the pathogenesis of Helicobacter felis, believed not to adhere to the murine mucosa. Methods and results: Using primary cell cultures, we found that H. felis can bind gastric epithelial cells in vitro, and adherence to epithelial cells deficient in Muc1 was increased compared to controls that expressed the mucin. However, following infection of deficient mice, we found that Muc1 did not impact on H. felis colonization or pathogenesis in vivo, in contrast to previous observations with H. pylori. Conclusions: This demonstrates a variable effect of Muc1 on protection against closely related adherent and nonadherent Helicobacter species, and supports a key role for Muc1 in limiting attachment of adherent bacteria to the gastric mucosal surface.     

In vitro propagation and assessment of genetic stability of micropropagated Samanea saman (rain tree) using microsatellite markers

An efficient in vitro propagation of Samanea saman (rain tree) protocol has been successfully developed using nodal explants from a 20-year-old tree. Higher percentage (76 %) of explants produced up to five shoots per explant on Murashige and Skoog (MS) medium supplemented with 2 mg L^?1 6-benzyladenine (BA), 0.1 mg L^?1 gibberellic acid (GA₃) and 100 mg L^?1 casein hydrolysate after 3 weeks of culture. When explants were subcultured to fresh medium after harvesting first batch of shoots, more shoots could be generated (another eight shoots per explant). Shoot elongation was achieved (3 cm) when shoots were cultured on MS medium supplemented with 0.25 mg L^?1 BA and 0.75 mg L^?1 GA₃. In vitro generated shoots rooted on MS medium fortified with 0.75 mg L^?1 indole-3-butyric acid plus 0.1 % of activated charcoal. A higher percentage of explant response and shoots per explant were obtained on MS medium with BA and GA₃. Each responsive nodal explant yields an average of 15 rooted plants within a period of 10 weeks. Rooted plantlets were successfully acclimatized in green house with a survival rate of 90 %. Micropropagated plants were tested for genetic stability using simple sequence repeats (SSR) markers. Use of the 12 high-resolution SSR markers revealed the exact same genetic profile between the mother tree (donor) and micropropagated plants, suggesting the genetic fidelity of our micropropagation protocol. The same protocol was also used successfully in propagating a “Golden Rain Tree” although response of explant and efficiency of propagation was much lower. This protocol will be useful for germplasm preservation/large scale production of true-to-type clones of desirable genotypes.