Biomedical subjects

X J Sun

Publications and source records attributed to X J Sun.

57 records · Page 4Linked to original sources

PubMed1990

[Diagnosis and surgical treatment of impotence caused by venous leakage].

Abnormal venous leaks are a causative factor of impotence and can be identified by perfusion cavernosography. The perfusion cavernosography was carried out in 47 impotent patients and the venous leakage was found in 21. Among 21 cases found the venous leakage, 20 cases underwent surgical treatment and the results showed that the patient's sexual life (erection) was not satisfactory after simple ligation of the deep dorsal vein and that ligation of the abnormal venous outlets at the level of the crura on penis was an effective way to restore potency. The authors consider that intra-cavernous papaverine injection induced penile erection is an effective means of screening for venous leakage.

Adult↗

PubMed1989

The heparin and pentosan polysulfate binding sites of human antithrombin overlap but are not identical.

Four sulfated polysaccharides (unfractioned heparin, low-molecular-mass heparin, heparan sulfate and pentosan polysulfate) were investigated for their abilities (a) to bind antithrombin, (b) to induce conformational change of the inhibitor and (c) to potentiate antithrombin inhibition of thrombin. The binding capacity was reflected by the shielding of the heparin binding site. This was characterized by the extent to which a polysaccharide could protect chemical modification of Lys-125 and Lys-136, two lysyl residues of antithrombin which have been implicated in heparin binding. The conformational change was measured by fluorescence enhancement and the increased accessibility of Lys-236 to chemical modification. Our results reveal that the events of polysaccharide binding, conformational change and the enhancement of inhibitory activity are not quantitatively interlinked. Compared to the unfractionated heparin on an equal mass basis, the low-molecular-mass heparin (molecular mass 4-6 kDa) binds more strongly to antithrombin, induces a greater conformational change (about twofold), but is less potent in accelerating the inhibitory activity. Both heparin and heparan sulfate shield Lys-125 and Lys-136 and induce a conformational change that leads to exposure of Lys-236 and an increased fluorescence. On the other hand, pentosan polysulfate protects only Lys-125 and causes no appreciable conformational change, although it is also capable of enhancing the antithrombin-thrombin interaction. These data clearly demonstrate that the heparin and pentosan polysulfate binding sites of antithrombin overlap (at Lys-125) but are not identical.

Antithrombins↗

PubMed1989

Heparin binding domain of human antithrombin III inferred from the sequential reduction of its three disulfide linkages. An efficient method for structural analysis of partially reduced proteins.

Human antithrombin III (AT-III) was partially reduced under mild conditions in the absence or presence of low molecular weight heparin. Quantitation of reduced disulfide bonds was facilitated by the application of a water-soluble color reagent, 4-N,N-dimethylaminoazobenzene-4'-iodoacetamido-2'-sulfonic acid (S-DABIA). The study shows that the three disulfide linkages of AT-III can be sequentially reduced, with Cys8-Cys128 being the most sensitive, followed by Cys21-Cys95, while Cys247-Cys430 is the most resistant to the mild reduction conditions. The rate of reduction of Cys8-Cys128 and Cys21-Cys95 was significantly decreased in the presence of heparin. The reduction of Cys8-Cys128 was also found to correlate quantitatively with the loss of heparin-accelerated antithrombin activity, heparin binding affinity, and heparin-induced fluorescence enhancement. These results suggest that Cys8-Cys128 is required for the integrity of the heparin binding domain of AT-III and support previous findings that lysyl residues surrounding Cys128 (Lys107, Lys114, Lys125, and Lys136) constitute an important part of the heparin binding site in AT-III.

Alkylation↗