Plasmin effect on platelet glycoprotein Ib-von Willebrand factor interactions

We have studied the effect of streptokinase on platelets in platelet- rich plasma (PRP) and of plasmin on washed platelets. By three and one- half minutes after the addition of 50,000 IU/mL streptokinase to PRP, the maximum rate of ristocetin-induced platelet agglutination declined 40%, and by 60 minutes, it declined 70%. During the same time interval, the thrombin time increased from 20 seconds to over 120 seconds. At a concentration as low as 50 IU/mL, streptokinase reduced the maximum rate of ristocetin-induced platelet agglutination by 50% and prolonged the thrombin time to 1.5 times control value. Streptokinase added to PRP also caused inhibition of platelet aggregation following stimulation by 2.9 mumol/L adenosine diphosphate, 0.25 U/mL thrombin, and 0.025 mg/mL collagen. Plasmin, 0.05 to 1.0 CU/mL, reduced ristocetin-mediated agglutination of washed platelets in the presence of von Willebrand factor (vWF) from 66% of control to 2% of control, following a one-hour incubation. Autoradiograms produced following sodium dodecyl-polyacrylamide gel electrophoresis (SDS-PAGE) of plasmin- treated 125I-surface-labeled platelets demonstrated progressive loss of a protein with a molecular weight (mol wt) of 180,000; simultaneously, a protein with mol wt 135,000 appeared on autoradiograms produced following SDS-PAGE of the surrounding platelet medium. These proteins are similar in molecular weight to glycoprotein (gp) Ib, a platelet surface receptor for vWF, and glycocalicin, a proteolytic fragment of gpIb. By use of an enzyme-linked immunosorbent assay (ELISA) based immunoinhibition assay for glycocalicin, we were able to demonstrate that plasmin treatment of washed platelets released a glycocalicin- related antigen into the surrounding medium and that appearance of this material corresponding to loss of vWF-dependent, ristocetin-induced agglutination.     

Improved retroviral transfer of genes into canine hematopoietic progenitor cells kept in long-term marrow culture

Amphotropic helper-free retroviral vectors containing either the bacterial neomycin phosphotransferase gene (NEO) or a mutant dihydrofolate reductase gene (DHFR*) were used to infect canine hematopoietic progenitor cells. In previous experiments, successful transfer and expression of both genes in canine CFU-GM were achieved after 24-hour cocultivation with virus-producing cells. The average rate of gene expression was 10% (6% to 16%) as measured by the number of CFU-GM resistant to either the aminoglycoside G418 or methotrexate. In an attempt to increase the efficiency of gene transfer, marrow was cocultured for 24 hours with either NEO or DHFR* virus-producing packaging cells and then kept in long-term marrow culture fed three times with virus-containing supernatant (2 to 5 x 10(6) CFU/mL). After six days, cells were harvested and cultured in CFU-GM assay with and without a selective agent. The average rate of gene expression in CFU- GM in five independent experiments was 46% and ranged from 19% to 87%. In conclusion, the efficiency of gene transfer into canine hematopoietic progenitor cells has been increased fourfold by combining cocultivation with long-term marrow culture as compared with results obtained with cocultivation only.     

Transduction of hematopoietic cells by foamy virus vectors

Foamy viruses are retroviruses of the spumavirus family that are often isolated from primary cultures of primate cells. We previously constructed vectors based on human foamy virus (HFV) and found that they were able to transduce a wide variety of vertebrate cells by integration of the vector genome. Here we show that several types of hematopoietic cells are efficiently transduced by an HFV vector that encodes alkaline phosphatase (AP). These cell types include transformed cell lines and primary hematopoietic progenitors from mice, baboons, and humans. The transduction rates of HFV vectors compare favorably with those obtained by murine leukemia virus vectors, which suggests that HFV vectors may be effective in the treatment of hematologic diseases by gene therapy.     

The mineralizing effect of zinc oxide-modified hydroxyapatite-based sealer on radicular dentin

Clinical Oral Investigations - The aim of this study was to evaluate the remineralization ability of three endodontic sealer materials at different root dentin regions. Cervical, medial, and apical...     

Crossmatch-compatible platelets improve corrected count increments in patients who are refractory to randomly selected platelets

BACKGROUND: HLA-matched platelets and crossmatch-compatible platelets are used to support thrombocytopenic patients who are refractory to randomly selected platelets. Data supporting the effectiveness of crossmatch-compatible platelets are limited, being essentially restricted to the subset of refractory patients previously shown to be alloimmunized. The authors' hospital does not test for alloimmunization. To determine the effectiveness of crossmatch- compatible platelets in an unselected group of refractory patients, the use of such platelets for all patients who are refractory to random- donor platelets was reviewed. STUDY DESIGN AND METHODS: All patients who received crossmatch-compatible platelets between January 1991 and May 1994 were retrospectively reviewed. All study patients were refractory to random-donor platelets, having two consecutive corrected count increments (CCIs) of < 10,000. A solid-phase red cell adherence method was used for platelet crossmatching, and CCI was used to monitor the effectiveness of each platelet transfusion. RESULTS: A total of 475 crossmatch-compatible platelet components were administered to 66 evaluable patients who were refractory to random-donor platelets. A significant improvement was found in the mean CCI when crossmatch- compatible platelets were compared with randomly selected platelets (p < 0.0001): an increase of 8000 +/? 6100 (mean +/? SD). In 59 percent (39/ 66) of the patients, the mean CCI improved to at least 7,500 and in 41 percent (27/66) to at least 10,000. If the 10 patients for whom crossmatch-compatible platelets were not identified are included, the mean CCI in 51 percent (37/76) of the refractory patients improved to at least 7,500; in 36 percent (27/76), it improved to at least 10,000. The effectiveness of crossmatch-compatible platelets did not decline with continued use. CONCLUSION: Crossmatch-compatible platelet components significantly improve the mean CCI for approximately one- half of patients who are refractory to random-donor platelets, even when the patients are not preselected for having alloimmunization to explain their refractory state.     

PRACTICAL MANAGEMENT OF PRIMARY VARICOSE VEINS

SUMMARY Varicose veins cause a great deal of morbidity in our population today. Despite the large amount of surgical time spent dealing with the problem, there is still a disappointingly high recurrence rate and many patients are investigated inadequately before surgery. This review considers the assessment of ‘simple’ varicose veins using a combination of tourniquet tests and a hand-held doppler probe. The place of more sophisticated investigative techniques is also discussed, in particular the value of duplex assessment in localising the variably sited sapheno-popliteal junction. Routine stripping of the long saphenous vein to the below-knee level is likely to decrease the recurrence rate of simple, long, saphenous varicose veins.     

Specific insulin assays, insulin sensitivity and blood pressure

Serum insulin concentrations have been used as markers of insulin resistance in population studies examining the relationship between insulin resistance and blood pressure, but the relationship is variable among studies. We hypothesized that differences in cross-reactivity of insulin assays with proinsulin and its split/des-amino products might account for the variation. We therefore examined fasting and post- glucose load serum insulin concentrations (determined by both specific and conventional assays), insulin sensitivity (measured by the euglycaemic clamp technique), and blood pressure, in a group of 56 diabetic (NIDDM) and non-diabetic subjects. Insulin concentrations as measured by the two methods were highly correlated (r = 0.97, p < 0.0001), and the relationships among serum insulin concentrations, insulin sensitivity and blood pressure were independent of assay method; for example, in non-diabetic subjects the univariate correlation between log10AUC insulin and insulin sensitivity index was similar with both methods [r = -0.81 vs. r = -0.82, p < 0.0001 (specific vs. conventional assay)]. Discrepancies between studies in the relationship between serum insulin concentrations and blood pressure are unlikely to be due to cross-reactivity of conventional insulin assays with proinsulin-like molecules.      

Polymorphous light eruption

Polymorphous light eruption (PLE) is a common idiopathic photosensitivity disorder with an estimated prevalence of 10-20%. It is characterized by an intermittent skin reaction to ultraviolet (UV) radiation exposure, consisting of non-scarring pruritic erythematous papules, vesicles or plaques that develop on light-exposed skin. Despite the different morphology in different individuals, the eruption tends to have a monomorphous presentation in any single subject. The histopathological features of PLE are distinct and comprise a perivascular lymphocytic infiltrate in the dermis, subepidermal oedema and variable epidermal changes. The pathogenesis of PLE is not well known, but findings suggest that it is a delayed-type hypersensitivity reaction to one or more UV-modified cutaneous antigens. The principal action of PLE is mainly in the UVA region, although some subjects exhibit sensitivity to UVB alone or to both UVA and UVB radiation at the same time. Preventive measures in PLE include the regular use of photoprotective methods combined with graduated exposures to natural sunlight. The induction of immune tolerance by phototherapy and photochemotherapy are useful prophylactic methods in moderate to severe cases. The role of systemic agents in the management of PLE is under investigation. This article reviews the epidemiological, pathogenetic and clinical aspects of PLE and discusses recent advances in the diagnostic approach and management of this condition.     

慢性乙型肝炎的口服抗病毒药物评价

美国食品和药品管理局（FDA）已批准拉米夫定（LAM）、阿德福韦（ADV）、恩替卡韦（ETV）和替比夫定（LdT）这四种口服抗病毒药物用于治疗慢性乙型肝炎（CHB）,其Ⅲ期临床试验的疗效、安全性及耐药情况总结于表1和表2。尽管每种药物均表现出良好的安全性,但对长期治疗而言也存在限制性。而且,这些药物均独立进行研发,仅作为单药治疗进行临床验证,