Plasticity of rat bone marrow-derived 5-hydroxytryptamine-sensitive neurons: dedifferentiation and redifferentiation

Inducing cellular dedifferentiation has been proposed as a potential method for enhancing endogenous regeneration in mammals. Here we demonstrate that phenotypic and functional neurons derived from adult rat bone marrow stromal stem cells (MSCs) can be induced to undergo dedifferentiation, then proliferation and redifferentiation. In addition to morphological changes and expression of neuronal markers, neuron-specific enolase and neurofilament H, functional differentiation was monitored by intracellular Ca2+ mobilization in response to a ubiquitous neurotransmitter, 5-hydroxytryptamine (5-HT) at different stages. The neurons derived from rMSCs were found to have increased 5-HT response. This 5-HT sensitivity could be reversed to basal level similar to that found in rMSCs when neurons, up to 3 days after neuronal induction, were induced to undergo dedifferentiation. Increase in 5-HT-induced Ca2+ mobilization was again observed when rMSCs derived from dedifferentiated neurons were induced to redifferentiate into neurons again. Variation in 5-HT1A receptor immunoreactivity was observed in stem cells, differentiated neurons, dedifferentiated neurons and redifferentiation neurons, consistent with their respective 5-HT sensitivity. These results suggest that adult bone marrow-derived 5-HT sensitive neurons are capable of dedifferentiation, then proliferation and redifferentiation, indicating their plasticity and potential use in treatment of neural degenerative diseases.     

Cost-effectiveness evaluation of different control strategies for Clonorchis sinensis infection in a high endemic area of China: A modelling study

Clonorchiasis is an important food-borne parasitic disease caused by Clonorchis sinensis infection. The evaluation of long-term cost-effectiveness of control strategies is important for disease control and prevention. The present study aimed to assess the cost-effectiveness of the three recommended strategies (i.e., WHO, Chinese and Guangdong strategies) and different combinations of commonly used measures (i.e., preventive chemotherapy, information, education, and communication (IEC) and environmental improvement) on clonorchiasis. The study area, Fusha town in Guangdong Province, was a typical high endemic area in China. The analysis was based on a multi-group transmission model of C. sinensis infection. We set the intervention duration for 10 years and post-intervention period for 50 years. The corresponding costs and DALYs were estimated. Strategies with incremental cost-effectiveness ratios (ICERs) less than 1/5 of the willingness-to-pay threshold were identified as highly cost-effective strategies. The optimal control strategy was obtained using the next best comparator method. The ICERs of Guangdong strategy were $172 (95% CI: $143-$230) US for praziquantel and $106 (95% CI: $85-$143) US for albendazole, suggesting the highest cost-effectiveness among the three recommended strategies. For praziquantel, 470 sets of control strategies were identified as highly cost-effective strategies for achieving infection control (prevalence<5%). The optimal strategy consisted of chemotherapy targeted on at-risk population, IEC and environmental improvement, with coverages all being 100%, and with the ICER of $202 (95% CI: $168-$271) US. The results for transmission control (prevalence<1%) and albendazole were obtained with the same procedures. The findings may help to develop control policies for C. sinensis infection in high endemic areas. Moreover, the method adopted is applicable for assessment of optimal strategies in other endemic areas.     

Characterization of neutralizing monoclonal antibodies recognizing a 15-residues epitope on the spike protein HR2 region of severe acute respiratory syndrome coronavirus (SARS-CoV)

Summary The spike (S) glycoprotein is thought to play a complex and central role in the biology and pathogenesis of SARS coronavirus infection. In this study, a recombinant protein (rS268, corresponding to residues 268–1255 of SARS-CoV S protein) was expressed in Escherichia coli and was purified to near homogeneity. After immunization with rS268, S protein-specific BALB/c antisera and mAbs were induced and confirmed using ELISA, Western blot and IFA. Several BALB/c mAbs were found to be effectively to neutralize the infection of Vero E6 cells by SARS-CoV in a dose-dependent manner. Systematic epitope mapping showed that all these neutralizing mAbs recognized a 15-residues peptide (CB-119) corresponding to residues 1143–1157 (SPDVDLGDISGINAS) that was located to the second heptad repeat (HR2) region of the SARS-CoV spike protein. The peptide CB-119 could specifically inhibit the interaction of neutralizing mAbs and spike protein in a dose-dependent manner. Further, neutralizing mAbs, but not control mAbs, could specifically interact with CB-119 in a dose-dependent manner. Results implicated that the second heptad repeat region of spike protein could be a good target for vaccine development against SARS-CoV.     

A synonymous mutation in NOD2 gene was significantly associated with non-specific digestive disorder in rabbit

Nucleotide-binding oligomerization domain containing 2 (NOD2) plays a pivotal role in the host innate and adaptive immunity by recognizing the pathogenic agents. Therefore, its genetic polymorphisms and association with susceptibility to infectious diseases have been widely reported in human and farm animals. In the present study, we investigated the genetic polymorphisms in 3171 bp coding region of NOD2 gene and association with non-specific digestive disorder (NSDD) in rabbit. A total of four coding single-nucleotide polymorphisms (cSNPs) were detected. Among them, c.2961C>T was further genotyped for case (n = 176) and control (n = 130) based on association analysis, which revealed that C allele carried the potential protective role for susceptibility to NSDD with the odds ratio (OR) values of 0.52 (95% confidence interval (CI) 0.37–0.73, P < 0.01). Under the dominant inheritance model, CC genotype was associated with decreased susceptibility to NSDD (OR = 0.38, 95% CI 0.24–0.60, P < 0.01). Along with the aggravation of NSDD, we observed higher mRNA expression of NOD2 gene (P < 0.05). However, the mRNA expression pattern of CC genotype would be interacted by the different status of NSDD, which only showed the significantly increased level in severe NSDD group (P < 0.05). These results revealed by genetic association and gene expression analysis suggested that the NOD2 gene was associated with the susceptibility to NSDD in rabbit. However, the causative mutations linked to c.2961C>T and corresponding functional depiction should be further explored by performing exhaustive genetic studies.     

Identifying Change Points in a Covariate Effect on Time-to-Event Analysis with Reduced Isotonic Regression

Isotonic regression is a useful tool to investigate the relationship between a quantitative covariate and a time-to-event outcome. The resulting non-parametric model is a monotonic step function of a covariate X and the steps can be viewed as change points in the underlying hazard function. However, when there are too many steps, over-fitting can occur and further reduction is desirable. We propose a reduced isotonic regression approach to allow combination of small neighboring steps that are not statistically significantly different. In this approach, a second stage, the reduction stage, is integrated into the usual monotonic step building algorithm by comparing the adjacent steps using appropriate statistical testing. This is achieved through a modified dynamic programming algorithm. We implemented the approach with the simple exponential distribution and then its extension, the Weibull distribution. Simulation studies are used to investigate the properties of the resulting isotonic functions. We apply this methodology to the Diabetes Control and Complication Trial (DCCT) data set to identify potential change points in the association between HbA1c and the risk of severe hypoglycemia.     

Distribution of sphingosine kinase activity and mRNA in rodent brain

Sphingosine-1-phosphate (S1P) is a lipid mediator that exerts multiple cellular functions through activation of a subfamily of G-protein-coupled receptors. Although there is evidence that S1P plays a role in the developing and adult CNS, little is known about the ability of brain parenchyma to synthesize this lipid. We have therefore analyzed the brain distribution of the enzymatic activity of the S1P synthesizing enzyme, sphingosine kinase (SPHK) [EC:2.7.1.91], as well as mRNA distribution for one of the two isoforms of this enzyme, sphingosine kinase 2. SPHK activity, measured by the conversion of [(3)H]sphingosine to [(3)H]S1P, is highest in cerebellum, followed by cortex and brainstem. Lowest activities were found in striatum and hippocampus. Sensitivity to 0.1% Triton-X suggests that this activity is accounted for by SPHK2. RT-PCR and in situ hybridization studies show that mRNA for this isoform has a distribution similar to that of SPHK activity. In vivo and in vitro ischemia increase SPHK activity and SPHK2 mRNA levels. These results indicate that SPHK2 is the predominant S1P-synthesizing isoform in normal brain parenchyma. Its heterogeneous distribution, in particular laminar distribution in cortex, suggests a neuronal localization and a possible role in cortical and cerebellar functions, in normal as well as ischemic brain.     

Effects of Sludge and pH Adjustment on Cd Speciation in Soil and Growth and Cd Accumulation in Pak Choi

The objective of this study was to assess the effects of soil pH adjustment and treatment with sludge on plant growth and cadmium (Cd) accumulation in Chinese cabbage (pak choi) grown in Cd-contaminated soils. Soil was artificially spiked to raise its final Cd concentration to 10 mg/kg, adjusted to different pH values, and then supplemented with 5% sludge: either biosolids (BS) from wastewater treatment or sludge from drinking water treatment (WTS). Pak choi seeds were sown and the seedlings potted in the treated soil, then grown in a greenhouse for 45 days. The added Cd was present mainly in the exchangeable fraction and its concentration correlated to Cd accumulation in the roots and shoots. Adjustment of pH and application of sludge affected the Cd concentration in different fractions. Addition of WTS and adjustment to pH 7.0 inhibited growth and Cd accumulation in the pak choi. Addition of BS increased the soil nutrient content and thus enhanced growth and Cd accumulation. If pak choi were the only form of vegetable intake, consumption of pak choi grown in the Cd-spiked soils used in this study would exceed the maximum acceptable intake (60 μg/day) proposed by the World Health Organization.     

Isolation and characterization of streptomycin-resistant mutants in Nicotiana plumbaginifolia

Summary Streptomycin-resistant colonies were isolated from protoplast cultures of haploid Nicotiana plumbaginifolia based on their ability to green in medium containing 1 mg/ml streptomycin sulfate. The frequency of resistant colonies was 0.9×10^–5 in nonmutagenized culture, and increased ten-fold following treatment of culture with 10 g/ml N-methyl-N-nitro-N-nitrosoguanidine. Of a total of 52 resistant clones isolated, 2 gave rise to haploid, 15 to diploid, and 3 to tetraploid plants upon transfer of calli to differentiation medium. Leaf-segment and protoplast assays showed that all diploid regenerates were resistant to streptomycin but sensitive to chloramphenicol, kanamycin, lincomycin, neomycin, and spectinomycin. Plants in most diploid clones were fertile and able to set seeds when self-fertilized and crossed reciprocally to wild-type plants. Inheritance of streptomycin resistance was studied in the diploid clones and, without exception, the resistance was transmitted maternally. Comparative studies of the ultrastructure of organelles and protein synthesis in isolated chloroplasts between wild-type and resistant clones in the presence of streptomycin suggest that streptomycin resistance is controlled by chloroplasts.     

Analysis of association at single nucleotide polymorphisms in the APOE region

The discussion of the prospects of using a dense map of single nucleotide polymorphisms (SNPs) to identify disease genes with association analysis has been extensive. However, there is little empiric evidence to support this strategy. To begin to examine the practical issues surrounding this methodology, we identified 10 SNPs in the region immediately surrounding the apolipoprotein E locus (APOE), an established susceptibility gene for Alzheimer disease. Our goal was to examine patterns of allelic association to begin to investigate the question of whether APOE could have been identified using SNPs. Our strongest evidence of association was at the 2 SNPs immediately flanking APOE.