抗CD49d单克隆抗体与rhG-CSF动员的外周血干细胞移植重建小鼠造血功能的比较研究

为比较研究抗CD49d单克隆抗体和重组人粒细胞集落刺激因子 (rhG CSF)动员的外周血干细胞对造血功能重建的影响 ,经放、化疗预处理的BALB/c小鼠分别接受经生理盐水(对照组 )、rhG CSF(实验 1组 )、抗CD49d单克隆抗体 (实验 2组 )动员的同系小鼠的外周血干细胞移植 ,观察受体小鼠的 4周存活率、外周血白细胞 (WBC)、骨髓有核细胞 (BMNC)、粒细胞巨噬细胞集落形成单位 (CFU GM)及脾集落形成单位 (CFU S)等指标。结果显示 ,实验 1、2组小鼠的 4周存活率、WBC、BMNC ,CFU GM和CFU S均明显高于对照组(P <0 0 1) ,实验 1、2组之间比较差异无显著性意义 (P >0 0 5 )。提示抗CD49d单克隆抗体或rhG CSF均能动员小鼠外周血干细胞 ,并能重建同系小鼠的造血功能。     

ISSag1 in streptococcal strains of human and animal origin

The chromosomal region of Streptococcus agalactiae harboring the C5a peptidase and the lmb genes displays the structure of a composite transposon. Its presence in a streptococcal strain is associated with the origin of this strain from a human host. In S. agalactiae it is flanked by two copies of the insertion element ISSag2, and the nucleotide sequence for a third IS element (ISSag1) can be found in this region. Based on amino acid sequence similarity of the deduced transposase ISSag1 belongs to the IS3 family. It is 1251 bp long and flanked by 37 bp imperfect inverted repeats. Horizontal gene transfer among different bacterial species is facilitated by mobile genetic elements. To investigate if ISSag1 homologues are also present in other streptococcal species, various species of pyogenic streptococci from animal and human origin were analyzed by Southern blot hybridization and PCR. Among the different streptococcal species, multiple copies of an ISSag1 homologue could only be detected in S. dysgalactiae subsp. dysgalactiae strains of animal origin. All of the S. agalactiae strains harbored only a single copy, that was always found in strains with the scpB-lmb composite transposon. A single copy of an ISSag1 homologue could also be detected in some of the S. pyogenes and S. dysgalactiae subsp. equisimilis strains. Nucleotide sequencing of the IS element in S. dysgalactiae subsp. dysgalactiae strains revealed several different variants. One of the variants showed the features of a regular IS3 element. The other two variants that were observed displayed a 500-bp deletion and a mosaic structure composed of ISSag1 and ISSag2 homologues. This mosaic structure suggests that recombination and horizontal gene transfer events in S. dysgalactiae strains of bovine origin could have played a role in the assembly of the scpB-lmb composite transposon structure.     

Interleukin-1 gene cluster polymorphisms and risk of Alzheimer’s disease in Chinese Han population

Summary. Interleukin-1 (IL-1) has been implicated as a key cytokine in Alzheimers disease (AD) pathogenesis. IL-1 gene polymorphisms, especially IL-1A C(^–889)T polymorphism, have been suggested to be associated with AD risk and onset age. To determine if IL-1 polymorphisms are genetic risk factors for developing AD in Chinese Mainland population, we analyzed IL-1A (^–889), IL-1B (^–511) and IL-1RN variable number of tandem repeat (VNTR) polymorphisms in a sample of 145 sporadic AD patients and 181 healthy controls. Our data revealed that the three polymorphisms in IL-1 gene cluster might not play a key role in AD pathogenesis in Chinese Mainland Han population.     

Inflammatory effects of snake venom myotoxic phospholipases A2.

Snake venom phospholipases A₂ (PLA₂) show a remarkable functional diversity. Among their toxic activities, some display the ability to cause rapid necrosis of skeletal muscle fibers, thus being myotoxic PLA₂s. Besides myotoxicity, these enzymes evoke conspicuous inflammatory and nociceptive events in experimental models. Local inflammation and pain are important characteristics of snakebite envenomations inflicted by viperid and crotalid species, whose venoms are rich sources of myotoxic PLA₂s. Since the discovery that mammalian PLA₂ is a key enzyme in the release of arachidonic acid, the substrate for the synthesis of several lipid inflammatory mediators, much interest has been focused on this enzyme in the context of inflammation. The mechanisms involved in the proinflammatory action of secretory PLA₂s are being actively investigated, and part of the knowledge on secretory PLA₂ effects has been gained by using snake venom PLA₂s as tools, due to their high structural homology with human secretory PLA₂s. The inflammatory events evoked by PLA₂s are primarily associated with enzymatic activity and to the release of arachidonic acid metabolites. However, catalytically inactive Lys49 PLA₂s trigger inflammatory and nociceptive responses comparable to those of their catalytically active counterparts, thereby evidencing that these proteins promote inflammation and pain by mechanisms not related to phospholipid hydrolysis nor to mobilization of arachidonic acid. These studies have provided a boost to the research in this field and various approaches have been used to identify the amino acid residues and the specific sites of interaction of myotoxic PLA₂s with cell membranes potentially involved in the PLA₂-induced inflammatory and nociceptive effects. This work reviews the proinflammatory and nociceptive effects evoked by myotoxic PLA₂s and their mechanisms of action.     

A structure based model for liposome disruption and the role of catalytic activity in myotoxic phospholipase A2s.

Venom phospholipase A₂s (PLA₂s) display a wide spectrum of pharmacological activities and, based on the wealth of biochemical and structural data currently available for PLA₂s, mechanistic models can now be inferred to account for some of these activities. A structural model is presented for the role played by the distribution of surface electrostatic potential in the ability of myotoxic D49/K49 PLA₂s to disrupt multilamellar vesicles containing negatively charged natural and non-hydrolyzable phospholipids. Structural evidence is provided for the ability of K49 PLA₂s to bind phospholipid analogues and for the existence of catalytic activity in K49 PLA₂s. The importance of the existence of catalytic activity of D49 and K49 PLA₂s in myotoxicity is presented.     

A case of IgM antibodies which inhibit the contact activation of blood coagulation

The relationship between the concentration of sulfinpyrazone circulating in the plasma and its effects on platelet function $\text{in}$$\text{vivo}$ is not well understood. We have studied the relationship between inhibition of $\text{in}$$\text{vivo}$ collagen-induced platelet aggregation and the sulfinpyrazone plasma concentration. Sulfinpyrazone was shown to inhibit $\text{in}$$\text{vivo}$ collagen-induced platelet aggregation in a dose-related manner and the inhibitory effects were directly related to the concentration of sulfinpyrazone in the plasma. In addition, with high doses, platelet aggregation $\text{in}$$\text{vivo}$ was inhibited for up to 18 hours after drug administration which was 14 hours after the sulfinpyrazone had been cleared from the plasma. These data suggest that a previously unidentified sulfinpyrazone metabolite is formed $\text{in}$$\text{vivo}$ which exerts a potent inhibitory effect on platelet function.     

Influence of exogenous estrogen on oocytic depletion induced by 7,12-Dimethylbenz[a]anthracene in mice

The influence of exogenous estrogen on the action of 7,12-Dimethylbenz[a]anthracene (DMBA) on ovaries of Swiss albino mouse has been studied. DMBA elicits the depletion of oocytes; but concomitant administration of estrogen with DMBA reduces this loss of oocytic population significantly.     

Affinity chromatography of soluble fibrin in human plasma on insolubilized fibrinogen and on fragment D from fibrinogen,non cross-linked or cross-linked fibrin

Normal human plasma containing approximately 2.5 mg of fibrinogen per ml, ¹³¹l-labelled fibrinogen (less than 0.1 mg per ml) and ¹²⁵l-labelled fibrin monomer (between 0.012 and 0.05 mg per ml) was subjected to affinity chromatography on insolubilized human fibrinogen (Fg-agarose), fragment D prepared from fibrinogen (FgD-agarose), fragment D from non cross-linked fibrin (FbD-agarose) or fragment D from cross-linked fibrin (D-D-agarose). The fibrin monomer was obtained by dissolving fibrin in 2 M NaBr. The fibrinogen and fragments D were highly purified materials which were coupled to CNBr-activated Sepharose in comparable molar amounts (8 mg per ml gel for the fragments D and 20 mg per ml gel for fibrinogen).The FgD- and D-D-columns had negligible affinity for fibrinogen in plasma, the Fg-column bound approximately 3 percent of the Fibrinogen and the FbD-column 1.5 percent.All columns showed very similar binding properties for soluble fibrin monomer both with respect to the amounts of fibrin adsorbed and the amounts eluted with 2 M NaBr. Thus the reported higher affinity of insolubilized fibrin monomer to fragment D prepared from fibrin compared to Fragment D from fibrinogen was not associated with a higher affinity of insolubilized fragments D from fibrin for soluble fibrin monomer.     

Calcium plays a key role in the effects induced by a snake venom Lys49 phospholipase A2 homologue on a lymphoblastoid cell line.

A catalytically-inactive Lys49 phospholipase A2 homologue from the venom of the snake Bothrops asper induces diverse effects (necrosis, apoptosis and proliferation) in a lymphoblastoid cell line, depending on the toxin concentration. The increments in cytosolic Ca2+ levels induced by this toxin in this cell line were assessed. At high toxin concentration (100 microg/mL) the toxin induces drastic disruption of the plasma membrane, associated with a prominent Ca2+ influx and necrosis. Previous incubation of the cells with the chelating agent EGTA or with ruthenium red, an inhibitor of the uniporter mitochondrial Ca2+ transport, greatly reduced necrosis. At a toxin concentration of 12.5 microg/mL, apoptosis is the predominant response, being associated with lower increments in cytosolic Ca2+. This effect was inhibited by preincubation with ruthenium red and the cytosolic Ca2+ chelator BAPTA-AM. The proliferative response, which occurs at a low toxin concentration (0.5 microg/mL), is associated with a small and oscillatory increment in cytosolic Ca2+. It was inhibited by EGTA, ruthenium red and BAPTA-AM, by inhibitors of the endoplasmic reticulum Ca2+ -ATPase (SERCA) and by blockade of the ryanodine receptor. It is concluded that necrosis and apoptosis induced by this toxin are associated with increments in cytosolic Ca2+ levels following plasma membrane perturbation, together with the involvement of mitochondria. The cellular proliferative response depends on a limited Ca2+ influx through the plasma membrane, being associated with a concerted functional unit constituted by SERCA, the ryanodine receptor and mitochondria, which regulate the observed oscillations in cytosolic Ca2+ concentration.