Interaction of high molecular weight kininogen, factor XII, and fibrinogen in plasma at interfaces

Using ellipsometry, anodized tantalum interference color, and Coomassie blue staining in conjunction with immunologic identification of proteins adsorbed at interfaces, we have previously found that fibrinogen is the main constituent deposited by plasma onto many man- made surfaces. However, the fibrinogen deposited from normal plasma onto glass and similar wettable materials is rapidly modified during contact activation until it can no longer be identified antigenically. In earlier publications, we have called this modification of the fibrinogen layer "conversion," to indicate a process of unknown nature. Conversion of adsorbed fibrinogen by the plasma was not accompanied by marked change in film thickness, so that we presumed that this fibrinogen was not covered but replaced by other protein. Conversion is now showen to be markedly delayed in plasma lacking high molecular weight kininogen, slightly delayed in plasma lacking factor XII, and normal in plasma that lack factor XI or prekallikrein. We conclude that intact plasma will quickly replace the fibrinogen it has deposited on glass-like surfaces by high molecular weight kininogen and, to a smaller extent, by factor XII. Platelets adhere preferentially to fibrinogen-coated surfaces; human platelets adhere to hydrophobic nonactivating surfaces, since on these, adsorbed firbinogen is not exchanged by the plasma. The adsorbed fibrinogen will be replaced on glass-like surfaces during surface activation of clotting, and platelets failing to find fibrinogen will not adhere.     

Absence of alternative splicing in bcr-abl mRNA in chronic myeloid leukemia cell lines

The major consequence of the Philadelphia (Ph) translocation in chronic myeloid leukemia (CML) is the formation of a bcr-abl hybrid oncogene encoding a tumor cell-specific protein P210bcr-abl. In contrast to this, in Ph chromosome-positive acute lymphoblastic leukemia (Ph + ALL), a P190bcr-abl can be observed. This P190bcr-abl has been implicated in acute rather than chronic leukemogenesis. Therefore, it can be hypothesized that the transition from chronic to blast phase in CML is accompanied by an alternative splice in the bcr-abl mRNA, which results in a switch of the production of P210bcr-abl into P190bcr-abl. Initial S1 nuclease protection mapping supported this theory. However, this result appears to be based on an artifact in the S1 analysis. By using the polymerase chain reaction we provide evidence for the absence of alternative splicing in bcr-abl mRNA in two CML blast crisis cell lines.     

Effect of active site-modified thrombin on the hydrolysis of platelet- associated glycoprotein V by native thrombin

To determine the relationship between equilibrium binding of thrombin to sites on the platelet surface and the cleavage of membrane glycoprotein V (GPV) by thrombin, we examined the effect of active site- modified thrombin (1-chloro-3-tosylamido-7-amino-L-2-heptanone thrombin toslysCH2-thrombin) on the binding of native thrombin to platelets and on the hydrolysis of GPV by native thrombin. ToslysCH2-thrombin inhibited binding of native thrombin to high affinity sites on the platelet surface. In contrast, hydrolysis of GPV by native thrombin, even at threshold thrombin concentrations, was not inhibited by pretreatment with toslysCH2-thrombin at concentrations up to 210 nmol/L. ToslysCH2-thrombin also had no appreciable effect on platelet aggregation or release of 14C-serotonin induced by native thrombin. Because toslysCH2-thrombin does not inhibit platelet release, aggregation, or GPV hydrolysis by native thrombin but does inhibit high affinity surface binding by native thrombin, these results indicate that thrombin binding and hydrolysis of GPV are separate and unrelated events.     

猪脑钠素及其类似物的合成

以固相多肽合成方法合成了猪的二十六肽脑钠素(BNP)和它的一个类似物(Mpr⁴,D-Ala^6,13)-BNP(4-24)-NH₂,保护肽用HF裂解除去保护基、在碱性条件下空气氧化形成二硫桥后,粗产物经凝胶过滤和高效液相色谱分离纯化,均有与天然脑钠素相同的活性。合成肽相对于树脂初始取代量的产率分别为9.56%和11.03%。     

交沙霉素在中国汉族、维吾尔族及哈萨克族中的药代动力学比较

交沙霉素在中国汉族、维吾尔族及哈萨克族中的药代动力学比较李国昌陈春雁杨明义（新疆石河子医学院第一附属医院药剂科，石河子８３２００８；石河子农学院医院，石河子８３２００３）为探讨交沙霉素（ｊｏｓａｍｙｃｉｎ）在不同民族正常人体内过程，我们用相同的受...     

Women worried about their familial breast cancer risk--a study on genetic advice in general practice

AIMS: To ascertain whether women who consulted their GP because they perceived themselves as at increased risk of familial breast cancer were indeed at increased risk, and to evaluate potential strategies for assessing genetic risk of breast cancer in general practice. METHODS: Sixty-seven out of 81 women who had consulted their GP for advice about their possible increased risk of developing breast cancer due to breast cancer in the family were interviewed. Familial breast cancer risk was assessed by a clinical geneticist. This assessment was compared with two recent guidelines for referral for genetic counselling. RESULTS: More than half (52%; n = 35) the women had a relative risk of two and over for developing breast cancer, while another half of these 35 (25%; n = 17) had a relative risk of three and over. All the women (n = 17) with a relative risk of three and over were identified by means of the two current guidelines for referral for genetic counselling, while more than half of the women (61%; n = 11) with a relative risk between two and three were identified. CONCLUSIONS: More than half the women concerned about their familial risk of breast cancer are indeed at increased risk of breast cancer. Current guidelines correctly identify women at high risk. However, doubts about the health gain and feasibility of referral warrant caution, and need further investigation.      

Immunopathology of the bronchial mucosa in 'late onset' asthma

A clinical, pathological and immunological study was made of fifty cases of asthma developing in adult life—twenty-seven females and twenty-three males. The mean age of appearance of asthma was 51 years. In spite of the paroxysmal onset observed in thirty-nine cases, the course was always severe, leading to dependence upon corticosteroid treatment in thirty-six cases. Two-thirds of the subjects had either a personal or familial atopic history, one-third had positive skin tests to routine respiratory allergens, and one-third had a peripheral blood eosinophilia higher than 400 mm³. Total serum IgE was not raised in any case and attempts at hyposensitization were not effective. The titre of serum complement was normal and investigation for autoantibodies was negative in thirty-one subjects. Study of the HLA system in twenty-eight cases showed a significantly raised frequency of antigen HLA9. The bronchial biopsies were examined histologically in thirty-one cases and by fluorescence examination in fifteen. The histological appearance was sterotyped and non-specific. There was some modification of the lining consisting of thickening and irregularity of the basal membrane with evidence of hyperfunction of adjacent mesenchymal tissues. The basal membrane showed thickening, estimated in two cases by electron microscopy to be of 20–30 μm. This was due largely to collagen, which concealed the true basal membrane, the ultrastructure of which was well preserved. Immunofluorescence tests made it possible to show the presence of IgA, IgG and IgM constantly associated with the C3 component of complement. This was localized mainly in the superficial part of the thickened basal membrane and in the cytoplasm of the epithelioid cells. Fibrin showed a different appearance, with irregular fluorescence situated essentially along the base of the superficial epithelial membrane. These immunofluorescence findings are compatible with transudation and also of a local immunological reaction.     

Erythropoietic protoporphyria: two populations of reticulocytes, with and without protoporphyrin

Erythrocytes from patients with erythropoietic protoporphyria contain large amounts of protoporphyrin. The photosensitivity experienced by these patients is assumed to be due to a leakage of protoporphyrin from the erythrocytes and transfer to the skin, where protoporphyrin acts as a photosensitizer. The leakage of protoporphyrin from the erythrocytes has been offered as an explanation for the great variety in protoporphyrin content observed among erythrocytes in this disease. Based on density gradient separation of red cells, it has been concluded that all reticulocytes and young erythrocytes contain large amounts of protoporphyrin. From our results, density gradient centrifugation is not suitable for age separation of red cells from patients with erythropoietic protoporphyria. By developing a new method for isolation of reticulocytes and applying flow cytometry to determine protoporphyrin content in individual cells, it was observed that two populations of reticulocytes were present in patients with erythropoietic protoporphyria, one with and the other without protoporphyrin. The half-life of protoporphyrin in red cells was found to be 12–14 days, in contrast to 1–2 days described previously, suggesting a slower release of protoporphyrin from the red cells than previously anticipated.