血小板活化与冠心病关系的研究进展

病理性血小板活化与血栓性疾病密切相关,在心血管疾病中,这一病理生理过程不仅与冠心病的发生、发展有着非常重要的联系,而且对于该病的治疗策略的优化和近、远期预后等方面都有直接的影响。     

Characterization of Latent Transforming Growth Factor-β From Human Seminal Plasma

PROBLEM : Human seminal plasma is known to exhibit immunosuppressive activity. Transforming growth factor β (TGF-β) has been identified as an immunosuppressive factor in human seminal plasma. Biologically active TGF-β represents a family of 25-kDa homodimeric proteins linked with disulfide bonds. TGF-β associates with high molecular weight proteins noncovalently to form a type of latency that is biologically inactive. Quantitative distribution of active form of TGF-β versus inactive latent form of TGF-β, and mechanism of the TGF-β activation in human seminal plasma remain to be elucidated. PURPOSE : To characterize seminal plasma latent form of TGF-β, including its concentration, and the mechanism underlying the activation of TGF-β. METHOD : Gel filtrations on ACA-34 and Biogel P-60 were used to fractionate seminal plasma. TGF-β was measured by enzyme immunoassay using antibodies specific for TGF-β₁ and TGF-β₂, respectively. Radioreceptor assay with recombinant human [¹²⁵I]-TGF-β₁ was applied to qualitatively identify TGF-β₁. Kinetic experiments with various pH, temperature and time, along with protease inhibitors, were performed to delineate the activation mechanism of latent TGF-β. RESULTS : Human seminal plasma contained both TGF-β₁ and TGF-β₂, predominantly in latent form. The total concentration of TGF-β₁ averaged 238 ng/ml versus an average of 18 ng/ml for TGF-β₂. The in vitro activation or release of TGF-β₁, from latent TGF-β₁ was achieved only at acidic pH of <4.0, and was time and temperature dependent. At pH 3.7 and 37°C, a significant activation of latent TGF-β₁ was achieved after an incubation of only 15 min, reached the maximum at 120 min, and the activated TGF-β₁ remained relatively stable for at least 24 h. The activation was not inhibitable by a series of protease inhibitors examined, alone or in combination (e.g., phenylmethylsulfonyl fluoride, E-64, pepstatin, leupeptin, ethylenediamine tetraacetic acid). Competitive radioreceptor assay established the functional identity of TGF-β₁ in human seminal plasma with recombinant human TGF-β₁. CONCLUSION : Human seminal plasma TGF-β is biologically activated from high molecular weight latent TGF-β by acid pH. The acidic environment of female lower genital tract could represent an in vivo physiological condition for activation of seminal plasma TGF-β that may immunologically protect the integrity of sperm.     

Granulocytes in bronchial lavage fluid after major vascular surgery

Increased numbers of polymorphonuclear granulocytes (PMN) in the airways, as measured by PMN content in bronchial lavage fluid (P less than 0.01), were found 3 h postoperatively in ten patients undergoing surgery for lumbar aortic aneurysms. An increase in plasma levels of the complement split product C3dg from 6 (0-19) AU/ml preoperatively to 20 (13-50) AU/ml 3 h after surgery (P less than 0.01), indicates an activation of the complement cascade. These changes were not accompanied by increased elastase activity in the bronchial lavage fluid or by major changes in pulmonary blood gas exchange or vascular resistance, indicating that massive PMN activation, analogous to that proposed in adult respiratory distress syndrome (ARDS) had not taken place. In conclusion, complement system activation and migration of PMN into the airways, as seen in connection with major vascular surgery, does not seem to contribute to ARDS-type pulmonary dysfunction.     

The effects of phorbol esters with different biological activities on protein kinase C

The sapintoxins are a series of naturally occurring fluorescent phorbol esters with a range of selective biological activities (e.g. pro-inflammatory but non-tumour promoting). Their ability to activate protein kinase C (PKC) in vitro has been studied. Both tumour promoting and non-promoting phorbol derivatives activate the enzyme in vitro at low concentrations. 12-deoxyphorbol-13-phenylacetate-20 acetate (DOPPA) acts as a partial agonist in the activation of protein kinase C. Structurally distinct phorbol esters may therefore preferentially activate different forms of protein kinase C. α-sapinine, a biologically inactive compound, binds to protein kinase C without stimulating the enzyme and prevents subsequent activation by phorbol esters such as 12-O-tetradecanoyl phorbol-13-acetate (TPA).     

Persistent platelet activation in patients with type 2 diabetes treated with low doses of aspirin

BACKGROUND: The percentage of diabetic patients who do not benefit from the protective effect of aspirin is larger than in other populations at cardiovascular risk. OBJECTIVE: We compared the ability of aspirin to suppress TxA2 and platelet activation in vivo, in type-2 diabetics vs. high-risk non-diabetic patients. METHODS: Urinary 11-dehydro-TXB2, plasma sCD40 L, and sP-selectin were measured, together with indices of low-grade inflammation, glycemic control, and lipid profile, in 82 patients with type-2 diabetes and 39 without diabetes, treated with low doses of aspirin. RESULTS: Urinary 11-dehydro-TxB2, plasma sCD40L and sP-selectin were significantly higher in diabetics than in controls: [38.9 (27.8-63.3) vs. 28.5 (22.5-43.9) ng mmol(-1) of creatinine, P = 0.02], [1.06 (0.42-3.06) vs. 0.35 (0.22-0.95) ng mL(-1); P = 0.0001], [37.0 (16.8-85.6) vs. 20.0 (11.2-35.6) ng mL(-1), P = 0.0001], respectively. The proportion of individuals with diabetes increased across quartiles of 11-dehydro-TxB2, sCD40L, and sP-selectin, with the highest quartiles of 11-dehydro-TxB2, sCD40L and sP-selectin, including 66%, 93.3%, and 93.3% of individuals with diabetes. Markers of platelet activation positively correlated with indices of glycemic control but not with markers of low-grade inflammation. CONCLUSIONS: Platelet dysfunction associated with insufficient glycemic control, may mediate persistent platelet activation under aspirin treatment.     

Modulation of glial cell signaling by adenosine and pharmacological reinforcement

In view of the increasing evidence that a pathological glial activation plays a significant role in the development of neurodegenerative diseases, we investigated the underlying molecular signaling as a possible target for a pharmacological therapy. Here, we are particularly focusing on the endogenous modulation of the Ca²⁺ and cyclic nucleotide-dependent signaling by the nucleoside adenosine and its reinforcement by the xanthine derivative propentofylline (PPF). As an experimental model, we used cultured rat microglial cells and astrocytes that are immature, show a high proliferation rate, and resemble in several aspects pathologically activated glial cells. A prolonged increase of the cellular cAMP level favored the differentiation of cultured astrocytes and associated properties required for the physiological nerve cell function. On the other hand, a strengthening of the cyclic nucleotide-dependent signaling inhibited potentially neurotoxic properties of cultured microglial cells. Similar effects were obtained by treatment with propentofylline, which mimicked modulatory adenosine effects and increased the intracellular level of cAMP and cGMP. Such a pharmacological glial cell conditioning, obtained by modifying the strength and the timing of these second messengers, may provide a therapy of neurodegenerative diseases in which a pathological activation of microglial cells and astrocytes is discussed to play a pathogenic role.     

Functional mri of human brain activation combining high spatial and temporal resolution by a cine flash technique

Functional mapping of human brain activation has been accomplished at high spatial and temporal resolution (voxel size 4.9 μl, temporal increment 100 ms). The approach was based on oxygenation-sensitive long-echo time FLASH MRI sequences synchronized to multiply repeated cycles of visual stimulation in a CINE acquisition mode. This high temporal resolution revealed that stimulus-related signal intensity changes in human visual cortex display an initial latency followed by increases extending over several seconds. Furthermore, the temporal characteristics of the complete CINE MRI signal time course depended on the absolute and relative durations of activation and control periods and, for example, caused an apparent absence of a poststimulation “undershoot” phenomenon. Complementing hyperoxygenation due to rapid hemodynamic adjustments, these results suggest signal intensity modulation by enhanced oxygen consumption and concomitant deoxygenation during prolonged and/or repetitive stimulation.     

Plasminogen activation in plasma of patients with systemic lupus erythematosus

Summary We measured ₂-plasmin inhibitor-plasmin complexes (PI-PC) in plasma of patients with systemic lupus erythematosus (SLE) to examine the plasminogen activation in SLE. The plasma PI-PC level in 23 patients with SLE was significantly higher than that in 18 normal subjects (P<0.001) and the SLE patients with nephrotic syndrome had higher plasma PI-PC levels than those without nephrotic syndrome (P<0.01). In addition, the plasma PI-PC level was significantly correlated with the level of plasma C3 breakdown products (iC3b/C3dg) in the patients with SLE (r=0.53, P<0.01). These results suggest that plasminogen is activated in plasma of patients with SLE and that the plasminogen activation may be associated with the activation of complement in SLE.     

Demonstration of microglial cells in and around senile (neuritic) plaques in the Alzheimer brain

Summary A monoclonal antibody, termed AD11/8, reactive to microglial cells, was produced by immunization of mice with partially purified amyloid fibrils of senile (neuritic) plaques. With immunoperoxidase staining on human tissues, AD11/8 also recognized macrophages in the red pulp of the spleen, Kupffer cells in the liver, and macrophages in the bone marrow. The results show that AD11/8 recognizes the antigens associated with mononuclear phagocytes lineage. In normal brains a few resting microglial cells were stained in gray matter, and less frequently in white matter. In senile dementia of the Alzheimer type numerous microglial cells were stained intensively and they often formed clusters in gray matter. By double immunostaining with AD11/8 and a polyclonal antibody against synthetic amyloid -protein, clustered microglial cells were observed in and around senile plaques with amyloid deposits. Some amyloid plaque cores were surrounded by microglial cell processes. These results indicate that microglial cells may play an important role in senile plaque formation.Supported in part by the Grant-in Aid for Scientific Research from the Ministry of Education, Science and Culture, the grants for Research of Dementia and for Primary Amyloidosis from the Ministry of Health and Welfare, Japan     

CD154-CD40-independent up-regulation of B7-2 on splenic antigen-presenting cells and efficient T cell priming by staphylococcal enterotoxin A

It has been demonstrated that in vivo T cell priming requires CD154-CD40 interaction, which is suggested to be critical in the induction of co-stimulatory activities on antigen-presenting cells (APC). In the current study, we demonstrate that in vivo administration of a high dose of a superantigen, staphylococcal enterotoxin A (SEA), could up-regulate B7-2 on most splenic APC independently of the CD154-CD40 interaction, followed by efficient expansion of SEA-reactive V(beta)3(+) T cells in CD154- or CD40-deficient mice. However, the CD154-CD40 interaction may be involved in SEA-mediated T cell activation, since a contribution of the CD154-CD40 interaction was observed when a lower dose of SEA was injected. CD154-independent T cell priming by SEA appeared also independent of the TRANCE-RANK pathway, which was shown to be capable of mediating CD154-independent activation of naive T cells during the infection of some viruses. These results indicate that SEA, which provokes rapid and efficient T cell responses without adjuvant, could utilize multiple CD154/TRANCE-independent pathways, to prime T cells.