Fasciola gigantica and hybrid Fasciola flukes, responsible for the disease fasciolosis, are found in Southeast Asian countries. In the present study, we performed molecular species identification of Fasciola flukes distributed in Terengganu, Malaysia using multiplex PCR for phosphoenolpyruvate carboxykinase (pepck) and PCR-restriction fragment length polymorphism (RFLP) for DNA polymerase delta (pold). Simultaneously, phylogenetic analysis based on mitochondrial NADH dehydrogenase subunit 1 (nad1) was performed for the first time on Malaysian Fasciola flukes to infer the dispersal direction among neighboring countries. A total of 40 flukes used in this study were identified as F. gigantica. Eight nad1 haplotypes were identified in the F. gigantica population of Terengganu. Median-joining network analysis revealed that the Malaysian population was related to those obtained from bordering countries such as Thailand and Indonesia. However, genetic differentiation was detected using population genetics analyses. Nevertheless, the nucleotide diversity (π) value suggested that F. gigantica with the predominant haplotypes was introduced into Malaysia from Thailand and Indonesia. The dispersal direction suggested by population genetics in the present study may not be fully reliable since Fasciola flukes were collected from a single location in one state of Malaysia. Further studies analyzing more samples from many locations are required to validate the dispersal direction proposed herein.
A simple and rapid single-step reverse transcriptase-polymerase chain reaction (RT-PCR) was used to investigate the nucleoprotein (N) gene of 11 rabies viruses. A conserved set of RT-PCR primers was designed to amplify the most variable region in the N gene. N gene regions were amplified from 6 fixed laboratory viruses, 4 street viruses from dogs in Thailand, and a horse in Zambia. Sequences of the amplified products, together with the database of 91 additional sequences, were analyzed by using PILEUP program of the GCG package. The rabies viruses grouped into at least 9 distinct clusters by < 90% nucleotide similarity of the N gene region: I (4 isolates, USA), II (2 isolates, South America), III (3 isolates, Africa), IV (52 strains, Europe, Middle East, Africa and South America), V (16 isolates, North America and Arctic), VI (17 isolates, Africa), VII (1 isolate, Africa), VIII (6 isolates, Thailand and Malaysia) and IX (1 isolate, Sri Lanka). A unique group of rabies viruses from Thailand and clusters of isolates corresponding to their geographic origin also were determined. The simple and rapid single-step RT-PCR proved to be useful for identifying rabies viruses, and for grouping the viruses into clades by sequence analysis.
Acute cardiovascular physical exercise improves cognitive performance, as evidenced by a reduction in reaction time (RT). However, the mechanistic understanding of how this occurs is elusive and has not been rigorously investigated in humans. Here, using positron emission tomography (PET) with [11 C]raclopride, in a multi-experiment study we investigated whether acute exercise releases endogenous dopamine (DA) in the brain. We hypothesized that acute exercise augments the brain DA system, and that RT improvement is correlated with this endogenous DA release. The PET study (Experiment 1: n = 16) demonstrated that acute physical exercise released endogenous DA, and that endogenous DA release was correlated with improvements in RT of the Go/No-Go task. Thereafter, using two electrical muscle stimulation (EMS) studies (Experiments 2 and 3: n = 18 and 22 respectively), we investigated what triggers RT improvement. The EMS studies indicated that EMS with moderate arm cranking improved RT, but RT was not improved following EMS alone or EMS combined with no load arm cranking. The novel mechanistic findings from these experiments are: (1) endogenous DA appears to be an important neuromodulator for RT improvement and (2) RT is only altered when exercise is associated with central signals from higher brain centres. Our findings explain how humans rapidly alter their behaviour using neuromodulatory systems and have significant implications for promotion of cognitive health. KEY POINTS: Acute cardiovascular exercise improves cognitive performance, as evidenced by a reduction in reaction time (RT). However, the mechanistic understanding of how this occurs is elusive and has not been rigorously investigated in humans. Using the neurochemical specificity of [11 C]raclopride positron emission tomography, we demonstrated that acute supine cycling released endogenous dopamine (DA), and that this release was correlated with improved RT. Additional electrical muscle stimulation studies demonstrated that peripherally driven muscle contractions (i.e. exercise) were insufficient to improve RT. The current study suggests that endogenous DA is an important neuromodulator for RT improvement, and that RT is only altered when exercise is associated with central signals from higher brain centres.