Spatial and temporal transmission risk of Dirofilaria immitis in Argentina

The aim of this work was to assess spatial and seasonal Dirofilaria immitis transmission risk throughout Argentina with models based on the temperature threshold below which filarial development will not proceed in the mosquito (i.e. 14 °C), the occurrence and the number of potential vector mosquito species, and the Heartworm Development Units derived from the degree-days concept. The four models showed a similar increasing southwest-northeast tendency and correlated significantly with canine prevalences used as external validation data. About one-third of Argentina would be suitable for heartworm transmission and the highest risk areas include the north-eastern provinces. According to our models, heartworm transmission is markedly seasonal with peaks in January and February; no region would support transmission throughout the year. To improve the present models, it is necessary to know which mosquito species are competent rather than potential vectors in the country. We believe the present study provides the first risk assessment maps for D. immitis transmission in the Southern Hemisphere and provides a useful guide for heartworm prevention during the transmission periods in different regions of Argentina.     

Horizontal transmission of a microsporidium from the convergent lady beetle, Hippodamia convergens Guérin-Méneville (Coleoptera: Coccinellidae), to three coccinellid species of Nova Scotia

Convergent lady beetles, Hippodamia convergens Guérin-Méneville, are a popular choice for aphid control in North America. An unidentified microsporidium was found in H. convergens adults that were purchased from a commercial insectary in 2004. This study examined egg cannibalism and egg predation as a means of horizontal transmission of the unidentified microsporidium among H. convergens larvae and three coccinellid species found in Nova Scotia: Coccinella septempunctata (seven-spotted lady beetle), C. trifasciata perplexa (three-banded lady beetle), and Harmonia axyridis (multicolored Asian lady beetle). The microsporidium was transmitted with 100% efficiency when first instars fed on microsporidia-infected eggs. Mean spore count data from smear preparations of infected beetles suggest that the infection was as heavy in C. trifasciata perplexa (a native coccinellid) (11.2 ± 0.96 spores/100 μm²) as it was in H. convergens (the natural host) (12.8 ± 1.16) but lighter in the introduced species C. septempunctata (7.5 ± 0.65) and H. axyridis (0.8 ± 0.11). For all of the beetle species examined, larval development was significantly longer for microsporidia-infected individuals than for their uninfected cohorts. The microsporidium had no effect on larval mortality. Based on the results of this study, field-collected H. convergens should be examined for microsporidia and uninfected individuals should be used to rear individuals for release in biological control programs. However, this is unlikely to happen because H. convergens are relatively easy and inexpensive to collect from their overwintering sites for redistribution.     

Dexamethasone has pro-apoptotic effects on non-activated fresh peripheral blood mononuclear cells

Apoptosis is a physiological method of cell death commonly referred to as programmed cell death. However, non-apoptotic programmed cell death, such as autophagy and programmed necrosis, has been characterized by morphological criteria. In view of the human therapeutic use of DEX, and considering that no difference in the number and/or affinity of glucocorticoid receptors in activated and non-activated lymphocytes has been reported, we decided to evaluate the effect of DEX on fresh peripheral blood mononuclear cells (PBMC). Transmission electron microscopy showed that DEX can significantly induce apoptosis in non-activated PBMC. It was also observed by transmission electron microscopy that, independently of DEX treatment, PBMC also died by a process marked by extreme vacuolization and increase in cellular volume; these cells were erroneously classified as viable by flow cytometry using the 7-AAD assay. It is concluded that the DEX pro-apoptotic effect is not restricted to activated PBMC and, therefore, DEX-induced apoptosis could play either homeostatic (activated PBMC) or immunosuppressive (non-activated PBMC) roles.     

Bacterial adhesion to sulcular epithelium in periodontitis

The purpose of this study was to investigate, by electron microscopy, the type of bacterial attachment to the sulcular epithelium in periodontitis. Gingiva biopsies were observed in a transmission electron microscope using cytochemical staining with ruthenium red for glycocalyx visualisation. In addition, subgingival plaque samples and biopsies from the sulcular epithelium in periodontitis from the patients were estimated microbiologically. Aerobic bacteria only were estimated in the subgingival plaque and both aerobic and anaerobic bacteria in the gingival biopsies. No bacterial internalisation could be observed. Fimbria-mediated adhesion as the only type of bacterial attachment and a large diversity of bacterial glycocalyces were detected. As the fimbrial adhesins of putative periodontal pathogens are able in vitro to induce inflammation and bone resorption via stimulation of the proinflammatory cytokine production, the demonstrated fimbrial adhesins suggest the significant role of bacterial adhesion to sulcular epithelium in periodontitis.     

Detection of Pseudo-nitzschia (Bacillariophyceae) species and amnesic shellfish toxins in Scottish coastal waters using oligonucleotide probes and the Jellet Rapid Test™

Species specific LSU rRNA targeted fluorescent oligonucleotide probes, designed by researchers at the Monterey Bay Aquarium Research Institute (USA) for a limited range of Pseudo-nitzschia species, were applied to unialgal cultures and Scottish field samples, to investigate possible applications in Scottish phytoplankton monitoring programmes to detect potential amnesic shellfish poisoning (ASP) toxin producing species. The existing available probe for Pseudo-nitzschia australis gave good results, positively labelling cells from cultures and field samples. However, application of the P. pungens, P. delicatissima and P. fraudulenta probes gave poor results, with little or no fluorescence label observed in field samples, while transmission electron microscopy (TEM) showed these species to be present. Comparison of the same region of the LSU sequence from cultures of P. delicatissima, isolated from Scottish waters, with the probe designed for detection of P. delicatissima isolated from Monterey Bay revealed the presence of a single base difference between the two sequences, which may have prevented the probe from hybridising to Scottish isolates and cells from field samples. In an attempt to assess the potential ASP toxin production by field populations of Pseudo-nitzschia a rapid immunodiagnostic test (the Jellet Rapid Test, JRT) for ASP toxins was examined. Results indicate that additional development of molecular probes for the detection of a range of Pseudo-nitzschia species detected in Scottish coastal waters and the use of JRT for toxin detection could conceivably provide an effective tool for broad-scale mapping of toxin events and management of coastal zone activities.     

Purinergic junctional transmission and propagation of calcium waves in cultured spinal cord microglial networks

In order to elucidate the mechanisms of purinergic transmission of calcium (Ca^2 +) waves between microglial cells, we have employed micro-photolithographic methods to form discrete patterns of microglia that allow quantitative measurements of Ca^2 + wave propagation. Microglia were confined to lanes 20–100 wide and Ca^2 + waves propagated from a point of mechanical stimulation, with a diminution in amplitude, for about 120 . The number of cells participating in propagation also decreased over this distance. Ca^2 + waves could propagate across a cell-free lane from one microglia lane to another if this distance of separation was less than about 60 , indicating that propagation involved diffusion of a chemical transmitter. This transmitter was identified as ATP since all Ca^2 + wave propagation was blocked by the purinoceptor antagonist suramin, which blocks P2Y₂ and P2Y₁₂ at relatively low concentrations. Antibodies to P2Y₁₂ showed these at very high density compared with P2Y₂, indicating a role for P2Y₁₂ receptors. These observations were quantitatively accounted for by a model in which the main determinants are the diffusion of ATP released from a stimulated microglial cell and differences in the dissociation constant of the purinoceptors on the microglial cells.     

Assembly of the protoplasm of Codium fragile (Bryopsidales, Chlorophyta) into new protoplasts

The cell organelles of the coenocytic alga Codium fragile (Sun) Hariot aggregated rapidly and protoplasts were formed when its protoplasm was extruded out in seawater. Continuous observation showed that there were long and gelatinous threads connecting the cell organelles. The threads contracted, and thus the cell organelles aggregated into protoplasmic masses. The enzyme digestion experiments and Coomassie Brilliant Blue and Anthrone stainings showed that the long and gelatinous threads involved in the formation of the protoplasts might Include protein and saccharides as structure components. Nile Red staining Indicated that the protoplast primary envelope was non-lipid at first, and then lipid materials Integrated Into its surface gradually. The fluorescent brightener staining Indicated that the cell wall did not regenerate in the newly formed protoplasts and they all disintegrated within 72 h after formation. Transmission electron microscopy of the cell wall of wild C. fragile showed electron-dense material embedded in the whole cell wall at regular intervals. The experiments indicated that C. fragile would be a suitable model alga for studying the formation of protoplasts.     

Skin thermal pain modeling—A holistic method

Pain sensation has been studied extensively, over a range of scales, from the molecular level to the entire human neural system. Thermal stimulation of pain has been widely used in the study of pain sensation. Skin thermal pain is induced through both direct (an increase/decrease in temperature) and indirect (thermomechanical and thermochemical) ways, and is governed by complicated thermomechanical–chemical–neurophysiologic responses. This paper is focused on the theoretical modeling of the underlying mechanisms in the process of skin thermal pain. A holistic model has been developed, which is composed of three sub-models, namely, transduction, transmission, and modulation and perception. The model can contribute to the understanding of thermally related pain phenomena in skin tissue and to improvements in a range of thermal therapeutic methods.     

汉坦病毒空气传播感染的实验室和野外采样研究

本项研究是通过动物实验和现场采样研究汉坦病毒气溶胶传播感染。用感染的黑线姬鼠排泄物自然形成的病毒气溶胶进行实验。黑红姬鼠感染后第5天放入离乳小鼠和乳小鼠,暴露10d,检测不到抗体,感染后第7天,放 乳小鼠和乳小鼠,暴露10d,可以检测出抗体;黑线姬鼠在暴露15d时,可以检测出抗体,可见黑线姬鼠感染后,第4天可能是它向体外排毒的一个时间标志,且形成的病毒气溶胶具有感染性。对现场采集的空气样品和收集的打谷者佩戴的口罩样品的研究发现,在稻田堆放的稻捆根部和鼠栖息的草窝的空气中每350L空气中和打谷场脱粒机附近每96L空气中,含有至少一个具有生物活性的汉坦病毒粒子,结合流行病学调查结果,可以判定,汉坦病毒经空气传播吸入感染可能是秋冬季节肾综合征出血热发病的主要传播途径。     

禾谷缢管蚜体内的病毒结合蛋白基因的克隆与原核表达

利用一对特异性引物,用PCR的方法从禾谷缢管蚜体内扩增出了病毒结合蛋白基因,序列测定结果表明其长度 为1647 bp,编码548个氨基酸,与GenBank中的禾谷缢管蚜美国生物型Buchnera groELNT核苷酸序列同源性为97%,氨基酸同源性为97.4%。构建了2个原核表达载体并进行表达得到了69kD融合蛋白和63kD的非融合蛋白。