Susceptibility of chick neural retina to viral multiplication in vitro during embryonic development

Summary Decrease in the susceptibility of embryonic chick neural retina cultures to the multiplication of various viruses was observed with increasing age of the embryo. In contrast the retinal cells supported the multiplication of Sindbis virus irrespective of the age when they were infected with the viral RNA. These results suggest that the restricted multiplication of the viruses observed is due to the modulated inability of the cell to process the adsorbed viruses for subsequent replication.     

Effect of human interferon on viral production in a cell line chronically infected by a type D retrovirus (Mason-Pfizer virus)]

Human interferon specifically inhibits the viral multiplication in a human cell line infected by a type D retrovirus, the Mason-Pfizer virus (MPV). This inhibition is less important than for type C viruses.     

Characterization of the partial inhibition, by deficiency in serum factors, of multiplication of SV3T3 transformed fibroblasts]

Partial inhibition, by serum starvation, of multiplication of SV3T3 transformed fibroblasts was studied by cultivating cells in a medium containing 1% of serum. Two different and successive states are described: a first step, with a rate of multiplication for 24 hrs, which is lowered (2 instead of 3 in a normal medium containing 10% of serum) but which remains constant (i.e. exponential multiplication), the observed inhibition being reversed by normal medium; a second step, where the rate of multiplication for 24 hrs, decreases very fast, and which is not reversible.     

Influence of a high-temperature environment on the development of experimental trypanosomiasis of the mouse]

Different evolutions of experimental trypanosomiasis are observed in Mice kept in a permanent 35 degrees C environment. Evolution depends on the individuality or the strain of the host animal. An experimental factor influence on the host mechanism defense rather than on the parasite multiplication rate is shown.     

Intracellular behaviour of Leishmania enriettii within murine macrophages

Both promastigotes and amastigotes of Leishmania enriettii were readily ingested by mouse peritoneal macrophages (MPM). Promastigotes after their entry within MPM were rapidly immobilized and their multiplication was never observed. Microscopic examination revealed that ingested promastigotes were degraded with MPM. Nonmotile amastigotes of L. enriettii taken up by MPM, on the other hand, multiplied intracellularly and eventually destroyed the infected cells.     

Rotavirus and gastroenteritis in the newborn infant. Initial observations]

A simplified method for the diagnosis of Rotavirus by electron microscopy is presented. The incidence of these viruses is observed in new-born infants and the relationship with acute gastroenteritis is recalled.     

Increased resistance in mice to Listeria monocytogenes after treatment with a fraction from an inflammatory granuloma]

The multiplication of Listeria monocytogenes in the spleen was decreased between the 3rd and the 11th day following the inflammatory reaction induced in Mice by subcutaneous implantation of talc embedded in a calcium phosphate gel into the dorsal area. A similar activity was observed after injection of SO4 (NH4)2 fractionated extracts from granuloma. The major activities were found in the 33% saturation precipitate and in the 80% saturation supernatant.     

Intracellular behaviour ofLeishmania enriettii within murine macrophages

Summary Both promastigotes and amastigotes ofLeishmania enriettii were readily ingested by mouse peritoneal macrophages (MPM). Promastigotes after their entry within MPM were rapidly immobilized and their multiplication was never observed. Microscopic examination revealed that ingested promastigotes were degraded within MPM. Nonmotile amastigotes ofL. enriettii taken up by MPM, on the other hand, multiplied intracellularly and eventually destroyed the infected cells.     

铜离子对绿色微囊藻增殖的影响

通过藻类增长潜力（AGP）实验,研究了不同浓度铜离子对绿色微囊藻（Microcystis viridis）增殖的影响。结果显示,低浓度的Cu^2＋（0．001～0．1mg／L）对绿色微囊藻的增殖有促进作用,高浓度的Cu^2＋（〉1mg／L）降低了藻细胞密度、叶绿素a以及微囊藻毒素的含量,抑制了绿色微裳藻的增殖。     

Avian influenza viruses infecting humans

Avian species, particularly waterfowl, are the natural hosts of influenza A viruses. Influenza viruses bearing each of the 15 hemagglutinin and nine neuraminidase subtypes infect birds and serve as a reservoir from which influenza viruses or genes are introduced into the human population. Viruses with novel hemagglutinin genes derived from avian influenza viruses, with or without other accompanying avian influenza virus genes, have the potential for pandemic spread when the human population lacks protective immunity against the new hemagglutinin. Avian influenza viruses were thought to be limited in their ability to directly infect humans until 1997, when 18 human infections with avian influenza H5N1 viruses occurred in Hong Kong. In 1999, two human infections with avian influenza H9N2 viruses were also identified in Hong Kong. These events established that avian viruses could infect humans without acquiring human influenza genes by reassortment in an intermediate host and highlighted challenges associated with the detection of human immune responses to avian influenza viruses and the development of appropriate vaccines.     

Azione dei virus poliomielitico e Coxsackie sulle cellule renali di scimmia (Macaca mulatta shaw)

Summary The authors found several modifications, particularly in the nucleolus, in kidney epithelial cells ofMacaca mulatta, kept in culture for 6–8 days, after infection with polio and Coxsackie viruses. They observed, after infection with polio virus, some groups of virus-like bodies, which indicate the possibility that a provocation took place in it.     

L- and conventional forms of micrococci in the circulating blood of thrombocytopenic patients.

The multiplication of Gram-positive Cocci originating from L-forms carried by platelets of autoimmune thrombocytopenic patients, may be attributed to the primary platelet damage enhanced following interaction with bacteria.     

Grape vine physiology: the contribution of culture in vitro

Conclusion In the area of cell and tissue physiology, the grape vine has been a major reference material. As with all woody perennials, in vitro technologies are relatively delicate. Nevertheless, remarkable progress has produced a situation where, during the past ten years, practical application of results from in vitro work has been envisaged. Reciprocal understanding has yet to be established between scientists developing micropropagation (multiplication with conformity to type) and those using in vitro methods for variety improvement (multiplication for novelty of type). I am convinced that the future should not see one of these objectives dominating the other. On the contrary, certain technologies should be developed to ensure a framework for conformity of propagation and others to obtain greater variability with the goal of plant improvement. This will render effective the two applications considered.     

Platelets and viruses: an ambivalent relationship

Thrombocytopenia is a frequent complication of viral infections providing evidence that interaction of platelets with viruses is an important pathophysiological phenomenon. Multiple mechanisms are involved depending on the nature of the viruses involved. These include immunological platelet destruction, inappropriate platelet activation and consumption, and impaired megakaryopoiesis. Viruses bind platelets through specific receptors and identified ligands, which lead to mutual alterations of both the platelet host and the viral aggressor. We have shown that HIV-1 viruses are internalized specifically in platelets and megakaryocytes, where they can be either sheltered, unaltered (with potential transfer of the viruses into target organs), or come in contact with platelet secretory products leading to virus destruction and facilitated platelet clearance. In this issue, we have reviewed the various pathways that platelets use in order to interact with viruses, HIV and others. This review also shows that more work is still needed to precisely identify platelet roles in viral infections, and to answer the challenge of viral safety in platelet transfusion.     

Ebola virus: the search for vaccines and treatments

Ebola viruses belong to the family Filoviridae, which are among the most virulent infectious agents known. These viruses cause acute, and frequently fatal, hemorrhagic fever in humans and nonhuman primates. Currently, no vaccines or treatments are available for human use. This review describes Ebola viruses, with a particular focus on the status of research efforts to develop vaccines and therapeutics and to identify the immune mechanisms of protection.     

Molecular aspects of the epidemiology of virus disease

With regard to molecular epidemiology, influenza A viruses belong to the best-studied virus systems. At least two large reservoirs of influenza A viruses have been built up in nature, one in humans and another one in water fowls. The latter one is very heterogenous, consisting of viruses belonging to 13 hemagglutinin (HA) and 9 neuraminidase (NA) subtypes in almost all possible combinations. The segmented structure of the influenza virus genome allows the creation of new influenza strains by reassortment. By replacement of the HA gene of human strains new pandemic viruses can be generated (antigenic shift). The particular structure of the HA enables the human influenza A-viruses to create variants which can escape the immune response of the host (antigenic drift). The nucleoprotein is responsible for keeping those two large reservoirs apart. Mixing of genes of viruses from these two reservoirs seems to happen predominantly by double infection of pigs, which apparently are tolerant for infection by either human or avian influenza viruses. The molecular mechanisms described for influenza viruses can be explained by the particular structure of their genome and their components and cannot be generalized. Each virus has developed its own strategy to multiply and to spread.     

RNA fragments, in vivo inhibitors of Shope fibroma and vaccinia virus multiplication]

RNA-fragments rich in purine nucleotides and resulting from degradation of ribosomal RNA from E. coli M 500 Sho-R with pancreatic RNase exhibit only in vivo an inhibitory effect on Shope fibroma and vaccinia virus multiplication.     

The invasion and growth of Babesia bovis in tick tissue culture.

Erythrocytic forms of Babesia bovis inoculated into cell cultures of the tick Boophilus microplus invaded the tick cells and showed multiplication for up to 48 h after inoculation.     

高速铁路无砟轨道不平顺谱

研究提出了我国高速铁路无砟轨道不平顺谱的计算方法、轨道不平顺谱拟合公式及轨道不平顺谱图.为提高轨道不平顺谱的计算精度,研究提出了基于线性插值和小波分析方法的轨道不平顺检测数据异常值和趋势向剔除算法.同时通过不同窗函数长度、不同窗函数和不同谱估计方法的轨道不平顺谱计算对比分析,确定了轨道不平顺谱的计算方法.利用高速综合检测列车检测数据计算确定了高速铁路无砟轨道不平顺谱及其拟合公式,并引入倍频能量表反映高速铁路无砟轨道周期结构的影响.由轨道不平顺谱拟合公式与倍频能量表共同构成的高速铁路无砟轨道不平顺谱,为高速铁路设计、评估和养护维修等提供了依据.     

Vegetative propagation of the cactusMamillaria woodsii craig through tissue cultures

Summary A new method of clonal multiplication is described in a representative from the Cactaceae family, which offers wide experimental and horticultural applications.