Safety and immunogenicity of the malaria candidate vaccines FP9 CS and MVA CS in adult Gambian men

We assessed the safety and immunogenicity of prime-boost vectors encoding the Plasmodium falciparum circumsporozoite (CS) protein expressed either in the attenuated fowl-pox virus (FP9) or modified vaccinia virus Ankara (MVA). Thirty-two adult Gambians in groups of four to eight received one, two or three doses of FP9 CS and/or MVA CS. No serious adverse event was observed following vaccination. The most immunogenic regimen was two doses of FP9 followed by a single dose of MVA 4 weeks later (an average of 1000 IFN-gamma spot forming units/million PBMCs). This level of effector T-cell responses appears higher than that seen in previously reported studies of CS-based candidate malaria vaccines.     

A clinical trial of prime-boost immunisation with the candidate malaria vaccines RTS,S/AS02A and MVA-CS

Heterologous prime-boost immunisation with RTS,S/AS02A and the poxvirus MVA-CS was evaluated in 18 healthy malaria-na?ve subjects in Oxford. Both priming with RTS,S and boosting MVA-CS, and the reverse, were found to be safe and well tolerated. T cell responses as measured by IFN-gamma ex vivo ELISPOT were induced, but the responses were low to moderate in both groups, with heterologous boosting yielding only small increments in T cell immunogenicity and no increased antibody response. Protection against 3D7 Plasmodium falciparum sporozoite challenge 4 weeks after the final vaccination was equal for both regimens at 33% (95% C.I. 4.3-77.7%), with one subject remaining fully protected on rechallenge at 5 months.     

膦肽类化合物对血管紧张素转化酶的体外抑制活性及构效关系

设计与合成了一系列膦三肽化合物。测定化合物对血管紧张素转化酶的体外抑制活性。结果表明,有些化合物的体外抑制活性已接近captopril的水平。在此基础上,探讨抑制剂的结构与抑制活性之间的关系。     

Increased adiposity on normal diet, but decreased susceptibility to diet-induced obesity in mu-opioid receptor-deficient mice

The mu-opioid receptor encoded by the Oprm1 gene plays a crucial role in the mediation of food reward and drug-induced positive reinforcement, but its genetic deletion has been shown to provide food intake-independent, partial protection from diet-induced obesity. We hypothesized that mu-opioid receptor-deficient mice would show an even greater, intake-dependent, resistance to high-fat diet-induced obesity if the diet comprises a sweet component. We generated an F2 population by crossing the heterozygous offspring of homozygous female Oprm1(-/-) mice (on a mixed C57BL/6 and BALB/c genetic background) with male inbred C57BL/6 mice. Groups of genotyped wild-type (WT) and homozygous mutant (KO) males and females were fed either control chow or a high caloric palatable diet consisting of sweet, liquid chocolate-flavored Ensure together with a solid high-fat diet. Food intake, body weight, and body composition was measured over a period of 16 weeks. Unexpectedly, male, and to a lesser extent female, KO mice fed chow for the entire period showed progressively increased body weight and adiposity while eating significantly more chow. In contrast, when exposed to the sweet plus high-fat diet, male, and to a lesser extent female, KO mice gained significantly less body weight and fat mass compared to WT mice when using chow fed counterparts for reference values. Male KO mice consumed 33% less of the sweet liquid diet but increased intake of high-fat pellets, so that total calorie intake was not different from WT animals. These results demonstrate a dissociation of the role of mu-opioid receptors in the control of adiposity for different diets and sex. On a bland diet, normal receptor function appears to confer a slightly catabolic predisposition, but on a highly palatable diet, it confers an anabolic metabolic profile, favoring fat accretion. Because of the complexity of mu-opioid gene regulation and tissue distribution, more selective and targeted approaches will be necessary to fully understand the underlying mechanisms.     

Neural and metabolic regulation of macronutrient intake and selection

There is considerable disagreement regarding what constitutes a healthy diet. Ever since the influential work of Cannon and Richter, it was debated whether the 'wisdom of the body' will automatically direct us to the foods we need for healthy lives or whether we must carefully learn to eat the right foods, particularly in an environment of plenty. Although it is clear that strong mechanisms have evolved to prevent consumption of foods that have previously made us sick, it is less clear whether reciprocal mechanisms exist that reinforce the consumption of healthy diets. Here, we review recent progress in providing behavioural evidence for the regulation of intake and selection of proteins, carbohydrates and fats. We examine new developments in sensory physiology enabling recognition of macronutrients both pre- and post-ingestively. Finally, we propose a general model for central neural processing of nutrient-specific appetites. We suggest that the same basic neural circuitry responsible for the homoeostatic regulation of total energy intake is also used to control consumption of specific macro- and micronutrients. Similar to salt appetite, specific appetites for other micro- and macronutrients may be encoded by unique molecular changes in the hypothalamus. Gratification of such specific appetites is then accomplished by engaging the brain motivational system to assign the highest reward prediction to exteroceptive cues previously associated with consuming the missing ingredient. A better understanding of these nutrient-specific neural processes could help design drugs and behavioural strategies that promote healthier eating.     

Establishment of a Modified in Vitro Cultivation of Protoscoleces to Adult Echinococcus granulosus; an Important Way for New Investigations on Hydatidosis

Background

Echinococcus granulosus, a zoonotic cestode parasite, causative agent of hydatid cyst is endemic in many parts of the world including the Middle East. Study on different aspects of this parasite is very important and valuable. However, working with adult worms which their habitat situated in the small intestine of canids, is dangerous and risky. Achieving such risky situation needs a controlled condition which is cultivation of the organisms in the laboratory. In this regard, cultivation of E. granulosus protoscoleces leading to adult worms was established in the laboratory for the first time in Iran.

Methods

Under aseptic conditions a number of protoscoleces were cultivated in diphasic S.10E.H medium using CO2 incubator to produce adult worms.

Results

Different forms of parasites including pre-segmentation stages (PS1 - PS4) and segmentation stages (S5-S8) and developing stages in segmented worms (S10-S11) were observed and evaluated in these medium. Finally adult worms contained four proglottids with a large and distinct genital pore were observed 50-55 days post cultivation. These parasites do not produce fertile eggs and conclusively do not have risk of hydatid disease transmission to the researchers.

Conclusion

The mentioned method for producing E. granulosus adult worms can open a new window for researches and facilitate working on different aspects of hydatidosis especially for diagnosis, protection and treatment studies.     

Interaction of benzylidene-anabaseine analogues with agonist and allosteric sites on muscle nicotinic acetylcholine receptors

Background and purpose

Benzylidene-anabaseines (BAs) are partial agonists of the α7 nicotinic acetylcholine receptor (nAChR) but their mechanism(s) of action are unknown. Our study explores several possibilities, including direct interactions of BAs with the nAChR channel.

Experimental approach

Functional and radioligand-binding assays were used to examine the interaction of two BA analogues, 3-(2,4-dimethoxybenzylidene)-anabaseine (DMXBA) and its primary metabolite 3-(4-hydroxy-2-methoxybenzylidene)-anabaseine (4OH-DMXBA) with both agonist and non-competitive antagonist (NCA)-binding sites on muscle-type nAChRs.

Key results

Both BAs non-competitively inhibited ACh activation of human fetal muscle nAChRs and sterically inhibited the specific binding of the NCAs [piperidyl-3,4-3H(N)]-(N-(1-(2-thienyl)cyclohexyl)-3,4-piperidine ([³H]TCP) and [³H]dizocilpine to Torpedo nAChRs in the desensitized state. These compounds modulated [³H]tetracaine, [¹⁴C]amobarbital and [³H]TCP binding to resting nAChRs by allosteric mechanisms. Both BAs enhanced [³H]TCP binding when the nAChR was initially in the resting but activatable state, suggesting that both compounds desensitized the Torpedo nAChR. Although DMXBA failed to activate human fetal muscle nAChRs, 4OH-DMXBA was found to be a partial agonist. [³H]Nicotine competition-binding experiments confirmed that 4OH-DMXBA has higher affinity than DMXBA for the agonist sites, and that DMXBA is also a competitive antagonist.

Conclusions and implications

3-(4-hydroxy-2-methoxybenzylidene)-anabaseine is a partial agonist for human fetal muscle nAChRs, whereas DMXBA only has competitive and NCA activities. The NCA-binding site for BAs overlaps both the phencyclidine-and dizocilpine-binding sites in the desensitized Torpedo nAChR ion channel. The desensitizing property of BAs suggests another possible mode of non-competitive inhibition in addition to direct channel-blocking mechanisms.     

The efficacy of bismuth subsalicylate in the treatment of acute diarrhoea and the prevention of persistent diarrhoea

A controlled, randomized, double-blind study in Bangladeshi children (ages 4-36 mo) with acute diarrhoea was undertaken to determine whether bismuth subsalicylate (BSS) would prevent the development of persistent diarrhoea (PD) in young children. The children were randomized to two groups: 226 were given liquid oral BSS, (as Pepto-Bismol), 100 mg/kg/d for 5 d; 225 were given placebo of identical appearance. On admission to the study, the two groups were comparable both clinically and microbiologically. Rotavirus was found in 56% of all the children, and enterotoxigenic E. coli in 31% of a subsample studied. Children treated with BSS had less severe and less prolonged illness than those treated with placebo (p = 0.057). There was, however, no difference in the development of PD between the two groups (8% and 11%). Unexpectedly, patients treated with BSS gained significantly more weight (2.3%) than those treated with placebo (0.5%; p < 0.001) during the course of the study. No toxicity of BSS was detected. Conclusion: Treatment with BSS had a modest therapeutic effect on acute diarrhoea, as has been previously demonstrated, but with no suggestion of a therapeutic effect on the prevention of persistent diarrhoea in this group of patients.     

Role of collagen-adherent platelets in mediating fibrin formation in flowing whole blood

Activated platelets provide assembly sites for coagulation enzyme complexes and in this way can mediate coagulation during hemostasis and thrombosis. In this study, we examined the procoagulant activity of platelets adhering directly to fibrillar collagen, a main thrombogenic constituent of subendothelium. For this purpose, we used a human ex- vivo thrombosis model in which collagen-coated coverslips were exposed to flowing nonanticoagulated blood (shear rate, 65/s) for 5.5 minutes, which led to the deposition of adherent platelets, platelet thrombi, and fibrin. To examine the procoagulant activity of adherent platelets only, a selective antagonist of the platelet GPIIb-IIIa complex, Ro 44- 9883, was infused via a mixing device, resulting in a complete abrogation of platelet thrombus formation but leaving the collagen- adherent platelet layer intact. This platelet layer generated increased postchamber fibrinopeptide A (FPA) levels (203 +/- 33 ng/mL) as compared with control experiments without infusion of inhibitor (95 +/- 13 ng/mL). Concomitantly, fibrin deposition measured by morphometric analysis of cross-sections was also increased, as was the platelet adhesion to collagen. An immunochemical staining of fibrin fibers further showed that the adherent platelets formed the nuclei for fibrin fiber formation. This increase in fibrin deposition was mediated by the intrinsic factor X (F.X) activation complex on adherent single platelets, because almost complete inhibition of FPA generation (9 ng/mL) and fibrin deposition (0.4% +/- 0.2% coverage) was achieved upon coinfusion of the GP IIb-IIIa antagonist and active site-inhibited F.IXa. The large platelet thrombi that were deposited in control experiments contained no significant amounts of immunodetectable fibrin except at the thrombus base, where adherent platelets anchored the thrombi to the collagen surface. These results suggest that the collagen-adherent platelets are important promoters of coagulation during the initial phase of thrombogenesis by providing assembly sites for the F.X activation complex.     

Factors IXa and Xa play distinct roles in tissue factor-dependent initiation of coagulation

Tissue factor is the major initiator of coagulation. Both factor IX and factor X are activated by the complex of factor VIIa and tissue factor (VIIa/TF). The goal of this study was to determine the specific roles of factors IXa and Xa in initiating coagulation. We used a model system of in vitro coagulation initiated by VIIa/TF and that included unactivated platelets and plasma concentrations of factors II, V, VIII, IX, and X, tissue factor pathway inhibitor, and antithrombin III. In some cases, factor IX and/or factor X were activated by tissue factor- bearing monocytes, but in some experiments, picomolar concentrations of preactivated factor IX or factor X were used to initiate the reactions. Timed samples were assayed for both platelet activation and thrombin activity. Factor Xa was 10 times more potent than factor IXa in initiating platelet activation, but factor IXa was much more effective in promoting thrombin generation than was factor Xa. In the presence of VIIa/TF, factor X was required for both platelet activation and thrombin generation, while factor IX was only required for thrombin generation. We conclude that VIIa/TF-activated factors IXa and Xa have distinct physiologic roles. The main role of factor Xa that is initially activated by VIIa/TF is to activate platelets by generating an initial, small amount of thrombin in the vicinity of platelets. Factor IXa, on the other hand, enhances thrombin generation by providing factor Xa on the platelet surface, leading to prothrombinase formation. Only tiny amounts of factors IX and X need to be activated by VIIa/TF to perform these distinct functions. Our experiments show that initiation of coagulation is highly dependent on activation of small amounts of factors IXa and Xa in proximity to platelet surfaces and that these factors play distinct roles in subsequent events, leading to an explosion of thrombin generation. Furthermore, the specific roles of factors IXa and Xa generated by VIIa/TF are not necessarily reflected by the kinetics of factor IXa and Xa generation.