华蟾蜍毒素对离体豚鼠输精管的作用

华蟾蜍毒素(华蟾素)使离体豚鼠输精管产生剂量依赖性收缩反应,利血平化豚鼠输精管及冷藏输精管对华蟾素反应减弱。给酚妥拉明、维拉帕米后,输精管对华蟾素反应均受抑制,溴苄胺可使反应潜伏期缩短。结果提示华蟾素收缩输精管反应可能与其促进肾上腺素能神经末稍NA释放有关。     

Haemopoietic growth factors.

Haemopoietic growth factors are involved in the production of the various blood cells from progenitors in the bone marrow, making them useful in a range of clinical situations. The genes for several of them have been cloned and their production engineered by recombinant technology, making them widely available. Myeloid growth factors are used to support patients in the aftermath of chemotherapy and bone marrow transplantation and have potential application in the treatment of infectious diseases. Erythropoietin is widely used for patients with anaemia due to failure of marrow production, having established its effectiveness in chronic renal failure. Thrombopoietin has recently been described and may provide a means to alleviate thrombocytopenia. Current indications and areas of recent reappraisal are addressed in this review.     

Perfluorochemicals as US contrast agents for tumor imaging and hepatosplenography: preliminary clinical results

In animals, perfluorochemicals (PFCs) are effective ultrasound (US) contrast agents that produce hepatic, splenic, and tumor enhancement. The use of Fluosol-DA 20%, an emulsion of perfluorodecalin and perfluorotripropylamine, was studied in nine non-critically ill patients with cancer who had liver lesions. US studies without Fluosol were compared with studies obtained 24, 48, and 72 hours after Fluosol infusion. Vital signs and extensive laboratory analyses are performed before and after Fluosol infusion. Liver metastases from colonic, pancreatic, and gastric carcinoma exhibited rim or diffuse enhancement after a Fluosol dose of 1.6 g/kg or greater. Fluosol produced echogenic enhancement of the liver and spleen relative to kidney at a dose of 2.4 g/kg, allowing the detection of nonenhancing lesions. In addition, Fluosol at a dose of 1.6 g/kg or greater allowed detection of lesions not seen before contrast medium was administered in three of the seven patients studied. There was a mild increase in the level of serum glutamic oxaloacetic transaminase in two patients, one given 2.4 and the other 3.2 g/kg of Fluosol. Mild and transient allergic reactions without change in vital signs were experienced by two patients.     

von Willebrand factor as a marker of endothelial cell activation following BMT.

Endothelial cell activation may play a role in thrombotic complications of BMT such as hepatic veno-occlusive disease (VOD), right atrial line thrombosis and microangiopathic haemolysis. To assess this, von Willebrand factor antigen (vWF:ag) was measured in 72 patients (25 allografts, 46 autografts and one syngeneic) during the first 6 weeks post-transplant. There was a significant rise in vWF:ag in both allografts and autografts but a greater increase was seen in the allografts. The changes in vWF:ag did not correlate with changes in C reactive protein showing that this was not merely an acute phase response. vWF multimers were normal in a subgroup of uncomplicated transplants showing that there was no large scale endothelial cell disruption. Patients with VOD did not have changes in vWF:ag that were consistently different from uncomplicated controls. Three of four patients who developed line thrombosis had higher levels of vWF:ag compared with control groups; multimeric structure of the vWF was again normal. These results show that there is endothelial cell activation post-BMT and that this is greater in allografts compared with autografts, thus suggesting a possible mechanism for the higher incidence of VOD in this group. There were no useful predictive markers of VOD or thrombosis in individual patients.     

Drug effects on an effortful operant: pentobarbital and amphetamine

The behavioral effects of amphetamine and pentobarbital depend upon the conditions maintaining behavior. For example, amphetamine usually decreases the rate of operant behavior maintained by fixed ratio schedules while pentobarbital either increases it or leaves it unaffected. However, when considerable exertion is required, as in situations that require endurance, amphetamine tends to enhance performance while barbiturates degrade it. These differences complicate predictions of the effects of these two drugs on effortful operants. The present experiment was designed to characterize effortful responding behaviorally and pharmacologically. Cebus monkeys were trained to operate a lever by flexing their arms and extending their legs; this response exerted a force approximating their body weight. This operant was maintained by a multiple fixed ratio fixed interval (Mult FR FI) schedule. The two schedules maintained dramatically different response patterns. The FR schedule maintained vigorous, high rate responding characterized by a narrow IRT distribution centered at 0.5 sec. The FI schedule maintained very low overall rates of responding characterized by a variable IRT distribution with a median of 1.5 to 2 sec. Despite very low rates of responding during the FI component, no consistent rate increases appeared after amphetamine, and 0.3 mg/kg eliminated responding altogether. Pentobarbital increased overall rate but also shifted the interresponse time (IRT) distribution toward longer IRTs. The increase in overall rate arose from an earlier onset of responding during the FI component and occurred simultaneously with response slowing. The present studies do not support suggestions of a generalized enhancement of effortful performance by amphetamine or a generalized degradation by pentobarbital.