The platelet amyloid precursor protein ratio as a diagnostic marker for Alzheimer’s disease in Thai patients

The platelet amyloid precursor protein (APP) ratio has recently been shown to be a promising diagnostic marker for Alzheimer’s disease (AD). To evaluate its usefulness in Thai patients, platelet APP was analyzed by immunoblotting. The APP ratio was calculated as the ratio of the combined band density of the 120-kD and 130-kD isoforms compared to that of the 110-kD isoform. The mean ages (and ranges) of 27 normal and 13 AD-affected subjects were 68.3 (60–84) and 79.3 (70–97) years, respectively. The Thai Mental State Examination (TMSE) scores demonstrated that the AD patients had significantly poorer cognitive functions than the normal subjects, with mean TMSE scores of 20.3 and 27.6 (maximum score of 30 points), respectively (p < 0.05). The platelet APP ratios of the AD patients were significantly lower than those of normal subjects: values (mean ± standard deviation) were 7.32 ± 1.29 and 9.13 ± 3.00, respectively (p < 0.05) for AD patients and normal subjects. However, the ranges of the APP ratios from both groups markedly overlapped, which precluded the establishment of a cutoff level to differentiate between the AD and normal subjects. In addition, no significant correlations were observed between the platelet APP ratio and the TMSE score or between the APP ratio and the serum cholesterol in this study, in contrast to previous reports.     

Anxiolytic-like actions of reboxetine, venlafaxine and endurance swimming in stressed male rats

Despite being potent anxiolytic agents, benzodiazepines (BDZ) sometimes show reduced therapeutic efficacy in stressed rodents. However, the effectiveness of norepinephrine reuptake inhibitors (NRI) and serotonin-norepinephrine reuptake inhibitors (SNRI) or other anxiolytic interventions, e.g., exercise, remained elusive. Here, we demonstrated that male rats subjected to restraint stress for 4 weeks showed decreases in percent open arm time and open arm entry, as determined by elevated plus-maze test (EPM). Increases in inhibitory avoidance trial 2 and outer zone time were also observed in elevated T-maze (ETM) and open field test (OFT), respectively. To evaluate the anxiolytic-like actions of exercise and anxiolytic drugs, stressed rats were subjected for 4 weeks to swimming or daily gavage with 2mg/kg diazepam (BDZ), or 10mg/kg fluoxetine (selective serotonin reuptake inhibitor), reboxetine (NRI), or venlafaxine (SNRI). In EPM, the open arm activity was higher in the swimming, reboxetine-treated and venlafaxine-treated groups as compared to age-matched controls, while diazepam and fluoxetine were without effect. In ETM, a reduction in avoidance latency was observed only in swimming and venlafaxine-treated groups. However, the combined swimming and pharmacological treatment showed no additive anxiolytic-like effect. It could be concluded that restraint stress induced anxiety-like behaviors, which were not responsive to diazepam or fluoxetine, whereas reboxetine, venlafaxine and swimming showed anxiolytic-like actions in stressed rats.     

Specific primers for PCR amplification of the ITS1 (ribosomal DNA) of Trypanosoma lewisi

Trypanosoma lewisi is a mild or non-pathogenic parasite of the sub-genus Herpetosoma transmitted by fleas to rats. In a previous study we described pan-trypanosome specific primers TRYP1 which amplify the ITS1 of ribosomal DNA by hybridizing in highly conserved regions of 18S and 5.8S genes. These primers proved to be useful for detecting T. lewisi DNA in laboratory rats, but a recent large scale survey in wild rodents demonstrated a lack of specificity. In the present study, we designed and evaluated mono-specific primers LEW1S and LEW1R, for the detection and identification of T. lewisi by a single-step PCR. These primers were designed inside the highly variable region of the ITS1 sequence of T. lewisi ribosomal DNA. The product size of 220 bp is specific to T. lewisi. The sensitivity limit was estimated between 0.055 and 0.55 pg of DNA per reaction, equivalent to 1–10 organisms per reaction. All the PCR products obtained from 6 different T. lewisi isolates were more than 98% similar with each other and similar to the sequences of T. lewisi already published in Genbank. All DNA of 7 T. lewisi stocks from China gave the specific 220 bp product. We showed that LEW1S and LEW1R primers enabled sensitive detection and identification of T. lewisi infection in laboratory and wild rats. This assay is recommended for monitoring T. lewisi infections in rat colonies or for studying infections in the wild fauna. An absence of cross reaction with human DNA means that these primers can be used to investigate atypical trypanosome infections in humans. Given the risk of T. lewisi infection in human, we believe that these primers will be beneficial for public health diagnosis and rodents investigation programmes.     

Atmospheric dispersion of polycyclic aromatic hydrocarbons from open burning of agricultural residues in Chiang Rai,Thailand

California Puff Mesoscale Dispersion Model (CALPUFF) was applied to simulate concentrations and the spatial distributions of polycyclic aromatic hydrocarbons (PAHs) emitted from open burning of maize residues in Chiang Rai, Thailand. The model was simulated during the burning season between January 1 and April 30, 2014. The 95th percentile values of 24-h average concentration of total PAHs at 117 specified ground level receptors were calculated. The spatial distribution of predicted concentration is also illustrated. The modeled results indicated that the open burning of maize residues contributed to high PAH concentration in particularly at the receptors located near the burned areas. The cancer risk of carcinogenic PAHs was evaluated using the calculation of benzo(a)pyrene equivalent (BaPeq). The results show that the calculated BaPeq values on daily basis ranged from 0.1 to 18.6 ng m^?3. These concentrations exceeded the Chinese’s standard of 2.5 ng m^?3 at 26 among 117 receptors. It was estimated that about 20% of the population living in Chiang Rai was exposed to PAHs at this level. This finding suggests that the open burning of maize residues could significantly contribute to high cancer risk to local population. It is expected that the outcome of this study can support the setting up an appropriate mitigation strategy for reducing their emissions and health impacts on population in the affected areas.     

Friction and Mechanical Properties of Highly Filled Polybenzoxazine Composites: Nanosilica Particle Size and Surface Treatment

Frictional and mechanical properties of highly filled polybenzoxazine [poly(BA‐a)] composites which are influenced by nanosilica contents, particle sizes, and surface treatments are investigated. The coefficient of friction and wear resistance, storage moduli, and microhardness of the nanosilica‐filled poly(BA‐a) composites systematically increase with an increase of nanosilica content, while those values of the nanocomposites are improved with decreasing particle sizes at the equivalent nanosilica content. The modulus can be predicted by the Kerner model with the maximum packing fraction, while the microhardness of the nanocomposites is in agreement with the Halpin–Tsai model. The nanocomposites fabricated with untreated nanosilica particles exhibit higher frictional and mechanical properties when compared with the surface‐treated nanocomposites at the equivalent particle sizes. The interfacial interactions via covalent bond formation between the nanosilica and the poly(BA‐a) are determinative factors for the nanocomposite properties. Highly filled nanosilica‐poly(BA‐a) composites can be employed in various applications where wear‐resistance plays an important role.     

Sequence variability of the HIV type 1 protease gene in thai patients experienced with antiretroviral therapy

One hundred sequences of HIV-1 protease with the two flanking cleavage sites from 10 antiretroviral drug-treated Thai patients were examined for residue variability and for mutations at positions associated with the resistance to protease inhibitors. Seven patients were infected with CRF01_AE, two with subtype B, and one with a strain that did not belong to any of the currently identified subtypes or recombinant forms. A total of 46 out of the 99 positions (46%) in HIV-1 protease showed at least one amino acid change as compared with the HXB2 subtype B protease. Interestingly, 35% of these mutations were at positions associated with resistance to the PIs. The observation indicated that the viral protease is flexible in tolerating some degree of amino acid substitutions even in the critical regions under the selective pressure driven by antiretroviral drugs. The PR/RT cleavage site revealed conservation of the HXB2 sequence. Nevertheless, the p6*/PR cleavage site displayed variability, notably in the p6* region.     

Comparison of microplate hybridization with gel electrophoresis and dot blot hybridization for the rapid detection of Mycobacterium tuberculosis PCR products

A microplate ELISA hybridization assay has been developed for the detection of the IS6110 PCR products of M. tuberculosis from sputum specimens. In this study, its efficacy was evaluated by comparison with agarose gel electrophoresis (AGE) and dot blot hybridization (DBH), with culture results as the 'gold standard'. The assay was used with 190 sputum samples: the PCR results detected by ELISA and AGE showed close agreement, with sensitivity, specificity and accuracy of 90%, 100% and 96% respectively. The same values for DBH were 92%, 98% and 96% respectively. The validities of these methods were not statistically significantly different (p>0.05). The agreement rates of PCR product detection by AGE comparing with DBH and ELISA were 0.964 and 0.964 respectively, while that of DBH and ELISA was 1.0 by Kappa analysis. The overall agreement was not statistically significantly different (p>0.05). Use of DBH or ELISA hybridization increased the sensitivity of detection by AGE 10-fold from 10 pg to 1 pg of purified DNA per reaction; ie from about 30 to about 3 organisms. The amount of PCR product detected by ELISA was only one half of that detected by the other methods; the total assay time of ELISA following the PCR was 4 hours. In conclusion, the microplate hybridization assay may replace AGE and DBH for the detection of the PCR products of M. tuberculosis because of its sensitivity, specificity and accuracy. Additional advantages of the microplate assay over AGE and DBH include rapidity, ease of use, greater safety, cost effectiveness and greater objectivity in the reading of results; the technique is suitable for use in epidemiological studies for the analysis of a large number of samples.