Search PubMed⌕ Search

Biomedical subjects

G Zhou

Publications and source records attributed to G Zhou.

At least 271 records · Page 15Linked to original sources
PubMed1990

[Relation of the changes in hemorheologic indices and the site and size of cerebral infarction].

According to the CT findings, 83 cases of cerebral infarction were divided into two groups. One group consisted of cases with occlusion of the cerebral arterial main trunks and the other of those with occlusion of the penetrating arteries. The HCT and the whole blood viscosity were higher in the former group, whereas the rate of platelet aggregation was higher in the latter group. These results suggested that the physiopathology involved in the formation of the large cerebral infarction in the cerebral cortex and subcortex was different from that of the small infarction in the deep cerebral structures. Besides, it was found that the blood viscosity has positive relationship with the size of the cerebral infarction in the former group. It was presumed that the HCT and the blood viscosity should be reduced immediately for treating the larger cerebral infarction, but to lower the rate of platelet aggregation for treating the small infarction in the deep cerebral structures would be of benefit.

Adult↗
PubMed1990

[1-stage reconstruction of microtia associated with hemifacial soft tissue aplasia].

Four cases of microtia association with hemifacial aplasia were repaired by one-stage reconstruction. The operations included external ear reconstruction and correction of facial deformity with free vascularized dermis fat flaps. All were successful, the results were satisfied. The method and the device of the operation are described in detail. The advantages of the technique are discussed.

Adult↗
PubMed1989

Identical linkage and cooperativity of oxygen and carbon monoxide binding to Octopus dofleini hemocyanin.

Employment of high-precision thin-layer methods has enabled detailed functional characterization of oxygen and carbon monoxide binding for (1) the fully assembled form with 70 binding sites and (2) the isolated chains with 7 binding sites of Octopus dofleini hemocyanin. The striking difference in the cooperativities of the two ligands for the assembled decamer is revealed through an examination of the binding capacities and the partition coefficient, determined as functions of the activities of both ligands. A global analysis of the data sets supported a two-state allosteric model assuming an allosteric unit of 7. Higher level allosteric interactions were not indicated. This contrasts to results obtained for arthropod hemocyanins. Oxygen and carbon monoxide experiments performed on the isolated subunit chain confirmed the presence of functional heterogeneity reported previously [Miller, K. (1985) Biochemistry 24, 4582-4586]. The analysis shows two types of binding sites in the ratio of 4:3.

Animals↗
PubMed1989

An analytic solution to the Monod-Wyman-Changeux model and all parameters in this model.

Starting from the Monod-Wyman-Changeux (MWC) model (Monod, J., J. Wyman, and J. P. Changeux. 1965. J. Mol. Biol. 12:88-118), we obtain an analytical expression for the slope of the Hill plot at any ligand concentration. Furthermore, we derive an equation satisfied by the ligand concentration at the position of maximum slope. From these results, we derive a set of formulas which allow determination of the parameters of the MWC model (kR, C, and L) from the value of the Hill coefficient, nH, the ligand concentration at the position of maximum slope [( A]0), and the value of nu/(n-nu) at this point. We then outline procedures for utilizing these equations to provide a "best fit" of the MWC model to the experimental data, and to obtain a refined set of the parameters. Finally, we demonstrate the applicability of the technique by analysis of oxygen binding data for Octopus hemocyanin.

Hemocyanins↗
PubMed1989

Experience using microvascular anastomotic rings for the transplantation of 20 free flaps.

A new microvascular anastomosis technique was employed with success in 1985-1986 with the result of 18 free-flap survivals and 2 failures. The rate of success in microvascular anastomoses was 90.5 percent (38 of 42). The advantages of this technique are its simplicity, convenience, and safety, and it may shorten the duration of the operation. Our experience in using vascular anastomotic rings is presented.

Adult↗
PubMed1987

A reexamination of the reported B----Z DNA transition in nucleosomes reconstituted with poly(dG-m5dC).poly(dG-m5dC).

Polynucleosomes with poly(dG-m5dC).poly(dG-m5dC) have been reconstituted, and well-defined nucleosome core particles from these have been prepared. Upon addition of MgCl2 to the levels used to induce the B to Z transition in this highly methylated DNA, significant changes in the circular dichroism spectrum are observed in solutions of these particles. However, such core particles also exhibit a noticeable instability when compared to chicken erythrocyte core particles under the same conditions. The change in circular dichroism can be entirely accounted for on the assumption that only free nucleotide, released by core particle dissociation, undergoes the B----Z transition. Therefore, no evidence has been found for "Z nucleosomes" in these solutions. In fact, the histone-DNA interaction in the nucelosome seems to partially inhibit the B to Z transition of the DNA. The analysis of our results is consistent with a model in which all of the DNA that remains bound to the histone octamer retains the B form.

Animals↗
PubMed1983

Diffusion-controlled reactions of enzymes. An approximate analytic solution of Chou's model.

Based on Chou's model, a criterion was derived, by which one can judge whether or not the physical picture of the critical spherical shell described by Chou for an enzyme-substrate fast reaction system can emerge. Furthermore, for those reaction systems with such a physical picture, an approximate analytical solution was presented, which can be easily handled to calculate the upper limit of the diffusion-controlled reaction and the corresponding concentration distribution of substrate molecules on the surface of the major protein outside the active site. The results thus obtained are in good agreement with those computed by Chou et al. through the approach of numerical solution. Furthermore, the physical significance of the criterion and its relation to the critical spherical shell are substantiated during the process of derivation, which is very helpful for gaining an insight into this kind of biomolecular system with surprisingly high reaction rates.

Binding Sites↗