Max(a), a new low-frequency platelet-specific antigen localized on glycoprotein IIb, is associated with neonatal alloimmune thrombocytopenia

We have identified a new platelet-specific alloantigen, Max(a), responsible for a typical case of neonatal alloimmune thrombocytopenic purpura. The maternal serum reacted strongly with paternal platelets in the platelet immunofluorescence test, whereas platelet alloantigen typing showed that no known human platelet antigen (HPA)-system was involved. In the monoclonal antibody (MoAb)-specific immobilization of platelet antigens (MAIPA) assay, the new antigen was located on the platelet membrane glycoprotein (GP) IIb-IIIa complex, but immunoprecipitation and immunoblot experiments to further localize the antigen failed. However, in the MAIPA assay, the binding of the anti- Max(a) antibodies from the maternal serum was blocked by two anti-GPIIb MoAbs. Thus, the antigen appeared to be located on GPIIb. Analysis of the family lead to the identification of six additional Max(a+) individuals. Three of these six individuals and the father were tested in the platelet aggregation test and were found to be normal. In the analysis of normal donors, three of 500 were typed positive for the new platelet-specific antigen, indicating a phenotype frequency of 0.6% in the normal population. Platelet RNA was isolated from the newborn's Max(a)+ father and from a healthy donor phenotyped as Max(a-), reverse- transcribed, and the entire GPIIb coding region was amplified by polymerase chain reaction. Subsequent nucleotide sequence analysis showed a single G-->A substitution at position 2,603, predicting a valine-->methionine amino acid substitution at position 837 of the mature glycoprotein. This mutation abolished a BsiYI restriction site at the cDNA level and a BstNI restriction site at genomic DNA level, respectively. The genetic association between the new antigen and this point mutation was confirmed by allele-specific restriction analysis on cDNA and on genomic DNA, as well as by allele-specific primer amplification on genomic DNA. The new mutation is 19 bp upstream of the mutation underlying the HPA-3 system. Therefore, we also evaluated the association between Mas and the HPA-3 polymorphism. So far, all Max(a+) individuals were also found to be HPA-3b, whereas 50 HPA-3a individuals were all Max(a-). This may indicate that Max(a) is a variant of the HPA- 3 allele.     

α1D-Adrenoceptors contribute to the neurogenic vasopressor response in pithed rats

Summary— The aim of the present study was to assess the role of vascular α_1D-adrenoceptors in the sympathetic vasopressor response in vivo. Specifically, we evaluated the effect of a selective α_1D-adrenoceptor antagonist, BMY 7378 (8-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-8-azaspiro(4,5)decane-7,9-dione 2HCI), on the vasopressor response induced by preganglionic (T₇-T₉) sympathetic stimulation in the pithed rat. The vasopressor response was dose-dependently sensitive to inhibition by intravenous BMY 7378 (0.1, 0.31, 1 and 3.1 mg/kg), doses of 1 and 3.1 mg/kg being equally effective. Like BMY 7378, 5-methylurapidil (0.1, 0.31, 1 and 3.1 mg/kg) antagonized the vasopressor response to spinal stimulation; doses of 1 and 3.1 mg/kg were also equally effective. In combination experiments, BMY 7378 (1 mg/kg, iv) and the α_1A-adrenoceptor antagonist, 5-methylurapidil (1 mg/kg, iv), showed an additive effect. The present results demonstrate that the α_1D-adrenoceptor subtype plays an important role in the pressor response to sympathetic nerve stimulation in the pithed rat, and confirm the participation of the α_1A-adrenoceptor subtype in the same response.     

Therapeutic effects of supervised chlorhexidine mouthrinses on untreated gingivitis

AIM: The aim of the present study was to test the presumptive therapeutic effect of chlorhexidine digluconate in a population with untreated gingivitis and presence of abundant calculus. SETTING AND STUDY DESIGN: Sixty subjects (? mean age of 23.4) were recruited from a knitting factory in the Province of Guangdong, People's Republic of China. By applying a double-blind clinical trial design the participants were divided into two groups (Test and Control) and matched according to their mean GI scores. The Test group (n= 20) was assigned to two daily mouth-rinses for 6 days per week using 0.12% chlorhexidine digluconate (Peridex®). The Control group (n= 40) rinsed twice daily with a placebo solution. All the rinsings were supervised and timed for 45 S. No attempt was made to influence the oral hygiene habits of the participantS. Prior to and after 3 months of the supervised rinsing, plaque was scored using the Plaque Index system (PIl), and gingivitis was assessed using the criteria of the Gingival Index system (GI).Calculus was scored according to the Calculus Surface Severity Index system (CSSI), and stain was also graded by the Discoloration Index system (DI). RESULTS: After 3 months, the Test group (n= 13) showed significant reduction in mean PIl, GI and percentage of gingivial bleeding (GB%), while significant increases in mean DI were observed. The improvement in gingival health was observed at all regions with marked reduction in mean GI (from GI = 1.40 to 1.08) and GB% reduction by 24–52%. The proportion of GI = 2 was also reduced significantly from 50-36%. The Control group (n= 23) also showed a decrease in mean PIl but significant increases in the mean GI and GB%. Intergroup comparison showed statistically significant differences between mean GI, percentage of gingival bleeding (GB%) and mean DI for the test and control groups after 3 months of supervised rinsing. However, there were no significant intergroup differences for mean PIl. CONCLUSION: In conclusion, there was a significant effect of chlorhexidine on gingivitis, although the effect may be too limited to assure prognostic benefits in the prevention of future disease progression.     

Both tumor necrosis factor receptors, TNFR60 and TNFR80, are involved in signaling endothelial tissue factor expression by juxtacrine tumor necrosis factor alpha

We have investigated the role of the two distinct tumor necrosis factor (TNF) receptors (TNFR60 and TNFR80) in endothelial cell activation employing an in vitro model of tumor necrosis factor alpha (TNF-alpha)- dependent tissue factor production of human umbilical vein endothelial cells (HUVECs). In this model, tissue factor is produced either on addition of exogeneous TNF-alpha, or by induction of endogenous TNF- alpha via adhesion molecule-linked signal pathways. Under both conditions, tissue factor expression could be partially blocked by antagonistic antibodies against either TNFR60 or TNFR80 and was fully inhibited by simultaneous application of both antibodies. Selective inhibitors of either TNFR60 or TNFR80-induced signal pathways inhibited tissue factor expression, and selective triggering of either of the two TNF receptors by agonistic antibodies induced this response in HUVECs. Furthermore, a coculture system of HUVECs and Chinese hamster ovary transfectants expressing a noncleavable, exclusively membrane-bound form of TNF-alpha resulted in a potent activation of HUVECs with synergistic action of both TNF receptors. Together, these data underline the importance of juxtacrine pathways in endothelial cell activation of procoagulant functions and show that membrane TNF-alpha and both TNFR types play a critical role.     

Body composition in systemic lupus erythematosus

The objectives were to determine the body composition, and the effects of disease and corticosteroid therapy on body composition, in a population of female patients with systemic lupus erythematosus (SLE). All female SLE patients managed through a single centre were invited to participate in a cross-sectional study of body composition. Data were collected by standardized interview and examination, and review of medical records. Body composition was assessed by dual-energy X-ray absorptiometry (DXA). Eighty-two subjects were evaluated, 30 of whom were post-menopausal. Univariate linear regression analysis revealed a significant association of reduced fat-free mass with SLE severity [as measured by the Systemic Lupus International Collaborative Clinics (SLICC)] (P = 0.020), a history of corticosteroid exposure (P = 0.043) and age (P = 0.048). Reduced total body bone mineral density (BMD) was also significantly associated with SLICC (P < 0.001) and corticosteroid exposure (P = 0.017), and with age (P < 0.001), post-menopausal status (P = 0.003) and the duration of menopause (P < 0.001). Stepwise multiple linear regression analysis revealed a significant association between fat-free mass and total body, lumbar spine and femoral neck BMD (P = 0.007, P = 0.025, P = 0.003, respectively). Fat mass was significantly associated only with lumbar spine BMD (P = 0.008). In this SLE population, disease severity and corticosteroid exposure were independently associated with a negative effect both on total body BMD and on fat-free mass. Fat-free mass was a significant predictor of lumbar spine, femoral neck and total body BMD.      

甲基黄酮醇胺盐酸盐对豚鼠离体心房肌生理特性的作用

甲基黄酮醇胺盐酸盐(methylflavonolamine hydrochloride,MFA)是上海医工院合成的一种新化合物,前期实验发现MFA有抗多种实验性心律失常、抗心肌缺血、抗血小板聚集等作用,并且还证明该药对芦受体有弱阻断作用及Ca~(2 )拮抗作用。本文观察MFA对豚鼠离休心房肌生理特性的影响,探讨其抗心律失常的作用机理。