Biomedical subjects

Zhiyong Cui

Publications and source records attributed to Zhiyong Cui.

5 recordsLinked to original sources

PubMed2006

Electrical induction of spikes in the hippocampus impairs recognition capacity and spatial memory in rats.

In clinical studies, interictal EEG spikes (IS) have been associated with numerous neuropsychological abnormalities, ranging from transitory cognitive impairment to epileptic encephalopathies. Understanding the pathophysiological mechanisms of IS has been hampered by the lack of validated animal models. To mimic IS, a stimulating microelectrode was implanted in the ventral hippocampal commissure and a recording microelectrode in the CA1 region of the hippocampus of normal male rats. Spike patterns were induced using a series of electrical pulses 10-30 ms in duration with a frequency of 0.5-2Hz and a current of 0.2mA. The commissural stimulation-evoked population discharges in the hippocampus resembled naturally occurring IS in epileptic rats and, in no cases, resulted in behavioral seizures. For behavioral testing, the Morris water maze, radial arm maze, and object recognition tasks were used. Spikes were induced during sleep between the two sets of water maze trials; during the trials in the radial arm maze task; and prior to the sample phase and during the delay periods in the object recognition task. We demonstrated that rats that received spikes took longer to reach the escape platform in the second set of water maze trials; had significantly more reference errors and required more trials to complete the radial arm maze task; and had lower investigation ratios in the object recognition task. The results indicate that induction of spikes in the hippocampus results in impairment of spatial reference and nonspatial object recognition memory.

Animals↗

PubMed2005

Immune responses in Balb/c mice induced by a candidate SARS-CoV inactivated vaccine prepared from F69 strain.

The immunogenicity of a candidate-inactivated vaccine prepared from SARS-CoV F69 strain was evaluated in Balb/c mice. Potent humoral immune responses were induced under the elicitation of three times of immunizations at 2-week intervals with this vaccine, combined with three types of adjuvants (Freund's adjuvant, Al(OH)(3) adjuvant and CpG adjuvant). Titers of specific IgG antibodies in three test groups all peaked in the sixth week after first vaccination, but significant differences existed in the kinetics of specific IgG antibody levels. The strong neutralizing capacity exhibited in micro-cytopathic effect neutralization tests indicated the specific antibodies are protective. Western blot assay further demonstrated the specificity of the induced serum antibodies.

Animals↗

PubMed2004

A peptidyl transferase ribozyme capable of combinatorial peptide synthesis.

The formation of peptide bonds is a key step in both the chemical and biological synthesis of peptides. The ribozyme can use a wide range of amino acids as its substrate for the dipeptide synthesis. A library containing 29 peptides whose synthesis was catalyzed by this unique ribozyme was analyzed by mass spectrometry. These results implicate that ribozyme may have potential application in the peptide synthesis.

Combinatorial Chemistry Techniques↗

PubMed2002

Synthesis of pCpCpA-3'-NH-phenylalanine as a ribosomal substrate.

[reaction: see text] The trinucleotide cytidylyl(3'-->5'phosphoryl)cytidylyl(3'-->5'phosphoryl)-3'-deoxy-3'-(L-phenylalanyl) amido adenosine (CpCpA-NH-Phe) was synthesized by phosphoramidite chemistry from 3'-amino-3'-deoxyadenosine as the ribosomal substrate. The 3'-amino-3'-deoxyadenosine was first converted to 3'-(N-tert-butyloxycarbonyl-L-phenylalanine)amido-3'-deoxy-6-N,6-N,2'-O-tribenzoyl-adenosine and then coupled with cytidine phosphoramidite to produce the fully protected CpCpA-NH-Phe-Boc. The title product was obtained after removing all protection groups and then radiolabeled with (32)P to yield pCpCpA-NH-Phe, which demonstrated high activity for the peptidyl transferase reaction in the ribosome.

Molecular Structure↗

PubMed2002

A selected ribozyme catalyzing diverse dipeptide synthesis.

The sequence of events by which protein, RNA, and DNA emerged during early biological evolution is one of the most profound questions regarding the origin of life. The contemporary role of aminoacyl-adenylates as intermediates in both ribosomal and nonribosomal peptide synthesis suggests that they may have served as substrates for uncoded peptide synthesis during early evolution. We report a highly active peptidyl transferase ribozyme family, isolated by in vitro selection, that efficiently catalyzes dipeptide synthesis by using an aminoacyl-adenylate substrate. It was characterized by sequence and structural analysis and kinetic studies. Remarkably, the ribozyme catalyzed the formation of 30 different dipeptides, the majority of rates being within 5-fold that of the Met-Phe dipeptide required by the selection. The isolation of this synthetic ribozyme fosters speculation that ribozyme-mediated uncoded peptide synthesis may have preceded coded peptide synthesis.

Adenosine Monophosphate↗