Biomedical subjects

Zhao Gong

Publications and source records attributed to Zhao Gong.

3 recordsLinked to original sources

PubMed2005

Crystal structure of Escherichia coli SufA involved in biosynthesis of iron-sulfur clusters: implications for a functional dimer.

IscA and SufA are paralogous proteins that play crucial roles in the biosynthesis of Fe-S clusters, perhaps through a mechanism involving transient Fe-S cluster formation. We have determined the crystal structure of E. coli SufA at 2.7A resolution. SufA exists as a homodimer, in contrast to the tetrameric organization of IscA. Furthermore, a C-terminal segment containing two essential cysteine residues (Cys-Gly-Cys), which is disordered in the IscA structure, is clearly visible in one molecule (the alpha1 subunit) of the SufA homodimer. Although this segment is disordered in the other molecule (the alpha2 subunit), computer modeling of this segment based on the well-defined conformation of alpha1 subunit suggests that the four cysteine residues (Cys114 and Cys116 in each subunit) in the Cys-Gly-Cys motif are positioned in close proximity at the dimer interface. The arrangement of these cysteines together with the nearby Glu118 in SufA dimer may allow coordination of an Fe-S cluster and/or an Fe atom.

Amino Acid Sequence↗

PubMed2003

Water self-diffusion tensor changes in an avian genetic developmental model of epilepsy.

Diffusion tensor imaging (DTI) was used to investigate whether tissue anisotropy in the developing brain is modified by recurrent seizures in epileptic chickens. Twelve epileptic chickens were sorted equally into two experimental groups at 10 days old. Until the age of 180 days, one group was photically stimulated beginning at an age of 2 weeks and repeated every 2 days while the other group was not stimulated. The photic stimulation induced generalized tonic-clonic seizures, and the unstimulated group did not display seizures. Both treatment groups were imaged at three time points, 45 (juvenile), 90 (adolescent), and 180 (adult) days posthatching, and maps of major and minor elements of anisotropy (eta and epsilon), trace and fractional anisotropy (FA) were generated. The eta, epsilon, and trace values in the hyperstriatum, archistriatum, and optic tectum showed significant changes as a function of developmental time point. Differences and/or interactions due to seizures were seen in the archistriatum and optic tectum for eta, epsilon, and trace with the largest differences between the stimulated and unstimulated birds being seen for eta in juvenile birds in the archistriatum (38.1 x 10(-11) m(2)/s versus 18.0 x 10(-11) m(2)/s) and the optic tectum (53.9 x 10(-11) m(2)/s versus 27.1 x 10(-11) m(2)/s). With the DTI parameters being sensitive to microstructure in the brain, these results demonstrate that seizures produce measurable differences, over unstimulated chickens, in brain structure for juvenile chickens, but the differences disappear as the brain matures. In other words, while seizure activity appears to induce atypical biophysical change (relative to unseizing birds) in the brain at a young age, the change is apparently reversed as the brain matures.

Adaptation, Physiological↗

PubMed2003

Recurrent nonstatus generalized seizures alter the developing chicken brain.

PURPOSE: Noninvasive magnetic resonance imaging was used to assess the evolution of seizure-induced pathology in epileptic, carrier, and normal chickens. Our objective was to determine whether repetitively evoked seizures in an epileptic fowl model of generalized seizures resulted in altered brain development. METHODS: Data were obtained from seizure and control groups at 45, 90, and 180 days after hatching. RESULTS: At 180 days, apparent diffusion coefficient (ADC) values in the optic tectum and archistriatum of the stimulated epileptic chicks were reduced, whereas ADC values in the nonstimulated group remained unchanged. The mean brain volume of epileptic chickens from the stimulated group was smaller than that from the nonstimulated group at 90 and 180 days. CONCLUSIONS: These findings establish that recurrent seizures modify the brain matrix.

Age Factors↗