Motor Function in MPTP-Treated Tree Shrews (Tupaia belangeri chinensis).

The tree shrew, a new experimental animal model, has been used to study a variety of diseases, especially diseases of the nervous system. 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is the gold standard for toxin-based animal models of Parkinson's disease (PD) because MPTP treatment replicates almost all of the pathological hallmarks of PD. Therefore, in this study, the effects of MPTP on the motor function of the tree shrew were examined. After five daily injections of a 3 mg/kg dose of MPTP, the motor function of MPTP-injected tree shrews decreased significantly, and the classic Parkinsonian symptoms of action and resting tremor, bradykinesia, posture abnormalities, and gait instability were observed in most MPTP-injected tree shrews. HPLC results also showed significantly reduced striatal dopamine and 3,4-dihydroxyphenylacetic acid levels in tree shrews after MPTP injection. Increased oxidative stress levels are usually considered to be the cause of dopaminergic neuron depletion in the presence of MPTP and were observed in the substantia nigra of MPTP-treated tree shrews, as indicated by a significant reduction in superoxide dismutase and glutathione peroxidase activity and increased levels of malondialdehyde. In addition, elevated α-synuclein mRNA levels in the midbrain of MPTP-treated tree shrews were observed. Furthermore, MPTP-treated tree shrews showed the classic Parkinsonian symptoms at a lower MPTP dosage compared with other animal models. Thus, the MPTP-treated tree shrew may be a potential animal model for studying the pathogenesis of PD.

[Diagnostic value of serum Cystatin C in renal function impairments in children with viral encephalitis].

OBJECTIVE: To study the value of serum Cystatin C (Cyst C) in the evaluation of glomerular filtration function in children with viral encephalitis. METHODS: Serum levels of Cyst C, urea nitrogen (BUN) and creatinine (Cr) were measured in 92 children with viral encephalitis and in 50 healthy children as a control group. According to glomerular filtration rate (GFR), the encephalitis group was subdivided into normal renal function, renal insufficiency in the compensatory or decompensatory stage, and renal failure /end-stage groups. RESULTS: Serum levels of Cyst C, BUN and Cr in the encephalitis group increased and GFR decreased significantly compared with those in the control group (P<0.01). With the decline of renal function, GFR decreased and serum levels of Cyst C, BUN and Cr increased gradually. Serum levels of Cyst C and GFR were significantly different among the encephaitis subgroups (P<0.01). For serum levels of BUN and Cr, there were significant differences among the subgroups except between the normal renal function and the compensatory renal insufficiency groups. Serum Cyst C level was positively correlated with serum BUN and Cr levels, and negatively correlated with GFR. CONCLUSIONS: The children with viral encephalitis have different degrees of renal impairments. Cyst C appears to be superior to BUN and Cr as a marker for the evaluation of glomerular filtration function. Measurement of serum Cyst C levels is very valuable in renal function monitoring in children with viral encephalitis.

Human and Tree Shrew Alpha-synuclein: Comparative cDNA Sequence and Protein Structure Analysis.

The synaptic protein alpha-synuclein (α-syn) is associated with a number of neurodegenerative diseases, and homology analyses among many species have been reported. Nevertheless, little is known about the cDNA sequence and protein structure of α-syn in tree shrews, and this information might contribute to our understanding of its role in both health and disease. We designed primers to the human α-syn cDNA sequence; then, tree shrew α-syn cDNA was obtained by RT-PCR and sequenced. Based on the acquired tree shrew α-syn cDNA sequence, both the amino acid sequence and the spatial structure of α-syn were predicted and analyzed. The homology analysis results showed that the tree shrew cDNA sequence matches the human cDNA sequence exactly except at nucleotide positions 45, 60, 65, 69, 93, 114, 147, 150, 157, 204, 252, 270, 284, 298, 308, and 324. Further protein sequence analysis revealed that the tree shrew α-syn protein sequence is 97.1 % identical to that of human α-syn. The secondary protein structure of tree shrew α-syn based on random coils and α-helices is the same as that of the human structure. The phosphorylation sites are highly conserved, except the site at position 103 of tree shrew α-syn. The predicted spatial structure of tree shrew α-syn is identical to that of human α-syn. Thus, α-syn might have a similar function in tree shrew and in human, and tree shrew might be a potential animal model for studying the pathogenesis of α-synucleinopathies.