The ‘space’ of friendship: young children's understandings and expressions of friendship in a reception class

The purpose of this study has been to explore young children's understandings and experiences of friendship as these manifested in children's behaviours, in a reception class setting. Drawing on an evolutionary, ecological framework, friendship is seen as not only the expression and further development of social understandings and cognitive advances; more than that, making and maintaining friends is seen as an evolutionary trait and a ‘drive’ to relate to similarly minded others. Through ‘niche picking’, children select the environments and opportunities that suit them in order to develop their dispositions and individual traits. The research employed a participatory design in order to capture the children's views and experiences. It took place in a reception class setting, where children's everyday experiences were observed and discussed with them. The study identified six themes of analysis and offered some suggestions about creating enabling educational environments that allow the ‘space’ for niche construction.     

Small interfering RNA inhibits SARS-CoV nucleocapsid gene expression in cultured cells and mouse muscles

SARS-CoV isa newly identified coronavirus that causes severe acute respiratory syndrome （SARS）. Currently, there is no effective method available for prophylaxis and treatment of SARS-CoVinfections. In the present study, the influence of small interfering RNA （siRNA） on SARS-CoV nucleocapsid （N） protein expression was detected in cultured cells and mouse muscles. Four siRNA expression cassettes driven by mouse U6 promoter targeting SARS-CoV N gene were prepared, and their inhibitory effects on expression of N and enhanced green fluorescence protein （EGFP） fusion protein were observed.     

黑柴胡中新三萜皂甙的结构鉴定

从黑柴胡(Bupleurum smithii Wolff)根中分离出10个化合物,均为首次由该植物中获得。其中二个新三萜皂甙,即柴胡皂甙k和l(saikosaponin k and l),其结构经紫外、红外、核磁共振氢谱,碳谱和质谱等波谱测定和解析,分别确定为3β,16β,23,28-四羟基齐墩果烷-11,13(18)-二烯-3-O-β-D-吡喃木糖基-(1→2)-β-D-吡喃葡萄糖基-(1→3)-β-D-吡喃呋糖甙和3β,16α,23,28,30-五羟基齐墩果烷-11,13(18)-二烯-3-O-β-D-吡喃葡萄糖基-(1→3)-β-D-吡喃呋糖甙。     

Application of a Polymerase Chain Reaction Enzyme Immunoassay in Peripheral Whole Blood and Serum Specimens for Diagnosis of Acute Human Brucellosis

A simple polymerase chain reaction-enzyme immunoassay (PCR-EIA) was employed for the rapid laboratory diagnosis of human brucellosis directly from peripheral blood. Whole blood and serum specimens were collected from 243 patients with acute brucellosis as determined by blood culture, serological tests, and the patients clinical characteristics and from a control group of 50 healthy individuals. Diagnosis of brucellosis was established in 179 cases by isolation of Brucella spp. in blood culture and in 64 cases by clinical signs and serological investigation. Following the amplification of a 223-bp sequence of a gene that codes for the synthesis of an immunogenic membrane protein specific for the Brucella genus, the amplified product was detected in a microtiter plate by hybridization. Two hundred forty-one of the 243 patients tested had detectable Brucella DNA in either whole blood or serum specimens: 149 (61.3%) patients were positive in both whole blood and serum specimens, 43 (17.7%) were positive in serum specimens only, and 49 (20.2%) were positive in whole blood specimens only. The diagnostic specificity of the PCR-EIA assay for both specimen categories was 100%, while the sensitivity was 81.5% for whole blood specimens, 79% for serum specimens, and 99.2% for whole blood and serum specimens combined. The results suggest that the detection of Brucella DNA in whole blood and serum specimens by PCR-EIA assay is a sensitive and specific method that could assist the rapid and accurate diagnosis of acute human brucellosis.     

Live nonpathogenic parasitic vector as a candidate vaccine against visceral leishmaniasis

To date, there are no proven vaccines against any form of leishmaniasis. The development of live attenuated vectors shows promise in the field of Leishmania vaccination because these organisms mimic more effectively the course of real infections and can elicit potent activation of the immune system. In the present study, we investigated the potential of a parasitic protozoan that is nonpathogenic to humans, Leishmania tarentolae, as a live candidate vaccine that efficiently targets dendritic cells and lymphoid organs, thus enhancing antigen presentation and consequently influencing the magnitude and quality of T-cell immune responses. We demonstrated that L. tarentolae activates the dendritic cell maturation process and induces T-cell proliferation and the production of gamma interferon, thus skewing CD4(+) T cells toward a Th1 cell phenotype. More importantly, we found that a single intraperitoneal injection of L. tarentolae could elicit a protective immune response against infectious challenge with Leishmania donovani in susceptible BALB/c mice. These results suggest that the use of L. tarentolae as a live vaccine vector may represent a promising approach for improving the effectiveness and safety of candidate live vaccines against Leishmania infections and possibly other intracellular pathogens for which T-cell mediated responses are critical for the development of protective immunity.     

Episomal and stable expression of the luciferase reporter gene for quantifying Leishmania spp. infections in macrophages and in animal models

We have expressed the reporter firefly luciferase gene (LUC) in Leishmania donovani and Leishmania major either as part of episomal vectors or integrated into the parasite genome under the control of their respective ribosomal promoter regions. An excellent linear correlation between parasite number and luciferase activity was observed with all the transfectants. LUC-expressing recombinant parasites were useful to monitor Leishmania spp. infections in macrophages or in animal models. For prolonged growth in absence of drug selection, such as within animal models, quantitation of parasites is more reliable when the reporter gene LUC is stably integrated in the parasite genome. These recombinant strains should be useful tools to monitor Leishmania growth under a number of conditions.     

Recombinant Leishmania major secreting biologically active granulocyte-macrophage colony-stimulating factor survives poorly in macrophages in vitro and delays disease development in mice

Leishmania is an intracellular pathogen that replicates inside macrophages. Activated macrophages produce a specific subset of cytokines that play an important role in the control of Leishmania infections. As part of our interest in developing suicide parasites that produce abortive infections for the purposes of vaccination, we engineered recombinant Leishmania major strains producing biologically active granulocyte-macrophage colony-stimulating factor (GM-CSF). We showed that GM-CSF is being produced in the phagosomes of infected macrophages and that it can be detected in the culture supernatants of both infected macrophages and extracellular parasites. Our data support the notion that GM-CSF secreted by both developmental forms of recombinant L. major can activate macrophages to produce high levels of proinflammatory cytokines such as interleukin-1beta (IL-1beta), IL-6, and IL-18 and various chemokines including RANTES/CCL5, MIP-1alpha/CCL3, MIP-1beta/CCL4, MIP-2/CXCL2, and MCP-1/CCL2, which enhance parasite killing. Indeed, GM-CSF-expressing parasites survive poorly in macrophages in vitro and produce delayed lesion development in susceptible BALB/c mice in vivo. Selective killing of intracellular Leishmania expressing cytokine genes capable of activating cellular responses may constitute a promising strategy to control and/or prevent parasitic infections.     

In-vitro translation of mitochondrial mRNAs by yeast mitochondrial ribosomes is hampered by the lack of start-codon recognition

Summary In an attempt to reconstitute an homologous in-vitro translation system for yeast mitochondrial mRNAs, we have isolated ribosomes, supernatant factors, and tRNAs from mitochondria of Saccharomyces carlsbergensis. While poly(U) is translated faithfully in this system, no translation of in-vitro synthesised cytochrome c oxidase subunit II (COX2) mRNA could be detected. Formation of formylmethionyl-puromycin on mitochondrial ribosomes is stimulated by ApUpG, but not by COX2 mRNA, although mitochondrial small ribosomal subunits bind to this mRNA in vitro, even without added tRNA and initiation factors. We conclude, therefore, that the inability to faithfully translate mitochondrial mRNAs in vitro may be the result of an inability of mitochondrial ribosomes to recognize the initiation codon.     

Chlorimipramine,electroconvulsive shock and combination thereof: Differential effects of chronic treatment on apomorphine-induced behaviours and on striatal and mesocortical dopamine turnover

Summary We studied the influence of different pretreatment regimens (Chlorimipramine-Cmi, electroconvulsive shock-ECS, and Cmi+ECS all regimens being applied for either 2 or 15 days) on the open field behaviour, on the striatal and on the prefrontal dopamine-PFC DA turnover in rats injected with either apomorphine-AP 25 g/kg (stimulating presynaptic DA receptors), AP 200 g/kg (stimulating postsynaptic DA receptors), or vehicle (control).In the controls, AP 25 g/kg reduced the locomotor activity and the striatal, but not the PFC DA turnover. AP 200 g/kg increased the locomotor activity and reduced the striatal but not the PFC DA turnover.Short-term pretreatment: ECS and Cmi+ECS prevented the decrease of striatal DA turnover after AP 25 g/kg. No other influence of any pretreatment on behaviour or DA-turnover became significant.Long-term pretreatment: Chronic Cmi: marginally increased the open field behaviour and marginally decreased the PFC DA turnover; significantly increased the effect of AP (200 g/kg) on striatal DA turnover and the effect of AP (25 and 200 g/kg) on PFC DA turnover. Repeated ECS: decreased locomotion and rearing and increased PFC DA turnover; increased the effect of AP (200 g/kg) on locomotion and on striatal DA turnover; decreased the effect of AP (25 and 200 g/kg) on PFC DA turnover.Chronic Cmi+ECS: decreased locomotion and rearing and marginally decreased PFC DA turnover; increased the effect of AP on hyperlocomotion and on striatal DA turnover. No other influence of any chronic pretreatment on behaviour or on DA turnover became significant.The data support the view that chronic AD therapies increase DAergic functions related to postsynaptic rather than to presynaptic structures. It is suggested that the different effects of chronic Cmi and repeated ECS on AP-evoked PFC DA turnover help to understand the different influences exerted by both treatments on rats' behaviour.     

Bispectral de-noising of the compound action potential for estimation of the nerve conduction velocity distribution

The distribution of the conduction velocities (DCV) of a peripheral nerve is a powerful diagnostic tool for the assessment of neuromuscular disorders. Its efficient calculation depends on the signal-to-noise ratio (SNR) of the acquired electroneurograms (ENGs), thus, time averaging is solely used. An alternative way of improving the SNR is based on averaging in the bispectrum domain and it is proposed in this work. The compound action potential (CAP) is a linear summation of the single fiber action potentials (SFAPs) propagating along the nerve fibers and can be expressed, in the discrete time, as the circular convolution of a delay sequence (DS) and the sampled SFAP. In the proposed method, averaging of low SNR CAP measurements is done in third order spectrum domain so no time alignment is required. Averaged bispectra are introduced in modified Hirose's method, to estimate the delay sequence for a conduction distance l1. The lost linear phase is recovered by using the delay phase cepstrum. Finally, the DCV can be calculated from the estimated DS, according to the formulation of the forward problem. Comparison between time and bispectrum averaging is performed using simulated data, proving the more efficient performance of the proposed method, especially in the case of noisy ENGs.