A comparison between activated protein C and des-1-41-light chain- activated protein C in reactions with type 1 plasminogen activator inhibitor

This study investigates the role of the gamma-carboxyglutamic acid (gla) containing domain of activated protein C in interactions with both platelet-derived and purified type 1 plasminogen activator inhibitor (PAI-1). The activity of human platelet PAI-1 was neutralized to the same extent by bovine activated protein C and bovine des-1-41- light chain-activated protein C. Both forms of activated protein C formed SDS-stable, divalent-cation independent complexes with platelet PAI-1, as demonstrated by immunoblotting using antibodies directed to either protein C or PAI-1. Since activated protein C neutralized PAI-1, the potential inhibition of the enzyme by PAI-1 was studied. Purified PAI-1 inhibited the amidolytic activity of bovine-activated protein C and bovine des-1-41-light chain-activated protein C with a k2 of 2.85 X 10(4) M-1 sec-1 for both proteins. These data suggest that the gla domain of activated protein C is not required for neutralization of PAI- 1 activity, for complex formation with PAI-1, or for inhibition of the amidolytic activity of activated protein C by PAI-1.     

The treatment of malignant histiocytosis

Twenty-four consecutive cases of malignant histiocytosis (MH) treated at Stanford Medical Center between 1973 and 1983 have been reviewed. Most patients presented with systemic symptoms (91%) and advanced disease (stage IV, 80%). Multiple organ involvement was common. In six cases, pathologic tissue was further characterized by frozen section immune histochemistry, using a panel of monoclonal antibodies known to react with monocytes and macrophages, as well as a variety of hematopoietic cells. One case expressed a mature monocyte/macrophage phenotype; three cases were considered null cell or primitive lesions; and two cases were identified as probable T cell lymphomas. Seven patients underwent splenectomy. Two patients died prior to any treatment. Twenty-two patients were treated with CHOP (cyclophosphamide, Adriamycin, vincristine, prednisone) +/- bleomycin (B), +/- midcycle high-dose methotrexate (HD-MTX) with leucovorin rescue. Seven patients received prophylactic intrathecal MTX. Of 22 evaluable patients, there was a 68% complete response rate (CR), a 23% partial response rate (PR), and a 9% no response rate (NR). Median duration of CR was 30+ months; median duration of PR was 2.4 months. Median survival for patients attaining a CR has not been reached v 3 months for the PR and NR groups. For all 24 patients, median survival was 2 years, with a 5-year actuarial survival of 40%. Multivariate analysis revealed that a platelet count less than 150,000 (P Cox = .005) and the dose of drug delivered (P Cox = .057) were the most important prognostic factors. Prophylactic intrathecal MTX therapy and splenectomy did not influence survival. Although MH is an aggressive disease with a poor prognosis, it is potentially curable. Systematic and aggressive treatment should further improve the outcome.     

Paediatric nodal marginal zone B‐cell lymphadenopathy of the neck: a Haemophilus influenzae‐driven immune disorder?

Many hyperplasias and lymphomas of marginal zone B‐cells are associated with infection. We identified six children and one adolescent with cervical lymphadenopathy showing prominent polyclonal nodal marginal zone hyperplasia (pNMZH) and four adolescents with monoclonal paediatric nodal marginal zone lymphoma (pNMZL). The clonality status was assessed using BIOMED‐2‐IG PCR analysis. Haemophilus influenzae was identified in all six cases of pNMZH that could be tested by direct culture (N = 3) or a very sensitive PCR for the H. influenzae gyrase gene in frozen materials (N = 5). H. influenzae was not detected in three pNMZLs and 28 non‐specific reactive cervical lymph nodes of age‐matched controls, except for a single control node that was obtained during oropharyngeal surgery for a cleft palate showing very low copy numbers of H. influenzae. pNMZH patients were younger than pNMZL patients (median age 12 versus 21 years). pNMZH showed a prominent nodular appearance with variable fibrosis without acute inflammation. Within the nodules, the expanded germinal centres and variably sized marginal zones were colonized by activated B‐cells with weak expression of IgD and lack of CD10 and/or BCL6 expression. Some areas showed skewed light chain expression in plasma cells (4/5 cases lambda). In four cases tested, this was confirmed by flow cytometry for surface Ig (3/4 cases lambda). In contrast, pNMZL showed more extensive expansion of marginal zones by centrocytoid cells and often expression of BCL2 protein. Several H. influenzae strains are known to interact with the constant part of IgD on human B‐cells, leading to their polyclonal proliferation and activation. We speculate that in vivo stimulation of IgD+ marginal zone B‐cells by this bacterium may be implicated in this particular lymphadenopathy that should be distinguished from monoclonal pNMZL. Copyright © 2015 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

BCL-6 expression during B-cell activation

Translocations involving the BCL-6 gene are common in the diffuse large cell subtype of non-Hodgkin's lymphoma. Invariably, the BCL-6 coding region is intact, but its 5' untranslated region is replaced with sequences from the translocation partner. The present study shows that BCL-6 expression is regulated in lymphocytes during mitogenic stimulation. Resting B and T lymphocytes contain high levels of BCL-6 mRNA. Stimulation of mouse B cells with anti-IgM or IgD antibodies, bacterial lipopolysaccharide, phorbol 12-myristate 13-acetate plus ionomycin, or CD40 ligand led to a five-fold to 35-fold decrease in BCL- 6 mRNA levels. Similar downregulation of BCL-6 mRNA was seen in human B cells stimulated with Staphylococcus aureus plus interleukin-2 or anti- IgM antibodies and in human T lymphocytes stimulated with phytohemagglutinin. BCL-6 mRNA levels began to decrease 8 to 16 hours after stimulation, before cells entered S phase. Although polyclonal activation of B cells in vitro invariably decreased BCL-6 MRNA expression, activated B cells from human germinal centers expressed BCL- 6 mRNA at levels comparable to the levels in resting B cells. Despite these similar mRNA levels, BCL-6 protein expression was threefold to 34- fold higher in germinal center B cells than in resting B cells, suggesting that BCL-6 protein levels are controlled by translational or posttranslational mechanisms. These observations suggest that the germinal center reaction provides unique activation signals to B cells that allow for continued, high-level BCL-6 expression.     

Evidence that fibrin alpha-chain RGDX sequences are not required for platelet adhesion in flowing whole blood

The role of the RGDX putative receptor-recognition sites, which are present on the alpha chains of fibrin, in promoting platelet adhesion has been examined in flowing whole blood using the rectangular perfusion chamber at wall shear rates of 340 and 1,600/s. Platelets adhered to a comparable extent to surfaces coated with native fibrin and surfaces coated with fragment X-fibrin, a product of limited fibrinolysis that lacks the RGDS sites normally present at positions 572 to 575 of the alpha chains. The strengths of these adhesive interactions were comparable based on the concentrations of the antiadhesive peptide D-RGDW required to block platelet deposition to native and fragment X-fibrin at both low and high wall shear rate. Blocking either or both RGDX sequences with peptide-specific monoclonal antibodies did not inhibit platelet deposition in perfusion experiments performed with normal blood at 340/s, indicating that neither RGD motif is required for adhesion. However, adhesion was partly inhibited by anti-RGDX antibodies when perfusions were performed with blood from an afibrinogenemic patient, suggesting the RGDX sequences may play a limited role in platelet deposition. Exposure of fibrin surfaces to plasminogen/tissue-type plasminogen activator did cause a time- dependent loss of adhesiveness, but this effect was only weakly correlated with proteolysis of the fibrin alpha chains. These observations provide evidence that neither RGDX sequence is required for platelets to adhere avidly to fibrin in flowing blood. These results further suggest that incomplete fibrinolysis yields a highly thrombogenic surface.     

A variant of von Willebrand's disease with abnormal expression of factor VIII procoagulant activity

Reports on variants of von Willebrand's disease are numerous, but many of these are based on tests that will show marked fluctuations with time and tests that might not be similar in affected family members. This report describes 8 patients with a new variant of von Willebrand';s disease in which there is a normal APTT, slightly reduced one-stage factor VIII:C assay (VIII:C-1), and a drastically reduced two- stage factor VIII:C assay (VIII:C-2). The VIII:C in this variant is more readily adsorbed to AI(OH)3. This variability in VIII:C assays and excessive adsorption to AI(OH)3 are corrected by the addition of either hemophilic plasma or hemophilic factor-VIII-related antigen. This variant is stable with restudy on multiple occasions and is inherited in a stable fashion in three generations of one family. The multimeric structure of the VIIIR:Ag appears normal, although the concentration is moderately reduced. The differences in functional activity, the adsorption to AI(OH)3, and the differences between functional and antigenic (VIII:C Ag) assays of VIII:C support that this is a functional abnormality of type I von Willebrand's disease.     

Localization of surface vWF on resting and stimulated platelets

We used immunoelectron microscopic localization techniques to investigate whether platelets stimulated by ADP or ristocetin in the plasma milieu bind von Willebrand factor (vWF) to their surfaces. We found by both peroxidase- and ferritin-based methods that unstimulated platelets lack vWF on their surfaces, whereas platelets that are stimulated with ADP or ristocetin have vWF associated with their surfaces. The specificity of the findings was confirmed by absorption studies using severe von Willebrand disease (vWD) and hemophilic plasmas. The anti-vWF antibodies were blocked by incubation with hemophilic plasma but not by incubation with severe vWD plasma. Thus, in the plasma environment, in the presence of fibrinogen, vWF becomes associated with the platelet surface subsequent to stimulation with ADP or ristocetin.     

Estimation of the age at onset in spinocerebellar ataxia type 2 Cuban patients by survival analysis

Almaguer‐Mederosa LE, Falcón NS, Almira YR, Zaldivar YG, Almarales DC, Góngora EM, Herrera MP, Batallán KE, Armiñán RR, Manresa MV, Cruz GS, Laffita‐Mesa J, Cyuz TM, Chang V, Auburger G, Gispert S, Pérez LV. Estimation of the age at onset in spinocerebellar ataxia type 2 Cuban patients by survival analysis. Previous studies have investigated the close association that exists between CAG repeat number and the age at onset in SCA2 = spinocerebellar ataxia type 2. These studies have focused on affected individuals. To further characterize this association and estimate the risk of a carrier developing SCA2 at a particular age as a function of a specific CAG repeat size, we have analyzed a large group of 924 individuals, including 394 presymptomatic and 530 affected individuals with a CAG repeat length of 32–79 units. Using a Kaplan–Meier survival analysis, we obtained cumulative probability curves for disease manifestation at a particular age for each CAG repeat length in the 34–45 range. These curves were significantly different (p < 0.001) and showed small overlap. All these information may be very valuable in predictive‐testing programs, in the planning of studies for the identification of other genetic and environmental factors as modifiers of age at onset, and in the design of clinical trials for people at enlarged risk for SCA2.     

ADA与EASD对2型糖尿病高血糖处理：治疗启动与评定的新共识方案

在不到一年时间由同一批专家代表ADA和EASD先后起草和发布了两次关于“2型糖尿病高血糖处理的共识声明”同时发表在2008年1月和12月的《DiabetesCare》和《Diabetologia》上。第一次共识声明内容主要围绕TZDs药物的安全性,本刊作了摘译转载（参阅《中国糖尿病杂志22008年第7期）。第二次修订的共识声明,关注点为降糖药的新分级,论据及观点比较清晰,故仍摘译供读者参考。