Buprenorphine does not affect acute murine toxoplasmosis and is recommended as an analgesic in Toxoplasma gondii studies in mice

Groups of mice were infected with tachyzoites of the RH strain of Toxoplasma gondii, treated with the opioid analgesic buprenorphine, sodium sulfadiazine, a combination of buprenorphine and sodium sulfadiazine, or nothing in the drinking water, on days -1 to 12 postinfection. Mice in the T. gondii-infected buprenorphine-treated group did not live significantly longer (P > 0.05) than mice given T. gondii and not treated with buprenorphine. Clinical observations of mice indicated that buprenorphine treatment reduced distress and pain in mice with acute toxoplasmosis. Mice treated with sodium sulfadiazine alone or sodium sulfadiazine combined with buprenorphine survived the 28-day study. Mice treated with buprenorphine and not infected with T. gondii also survived the 28 days. This study demonstrates that buprenorphine does not adversely interfere with acute T. gondii infection and indicates that buprenorphine can be given to mice to alleviate pain and distress associated with a T. gondii infection, and not adversely influence the results of toxoplasmosis studies. Analgesic (buprenorphine) treatment should now be the standard of care for mice in acute toxoplasmosis studies.     

The role of nitric oxide in the regulation of the systemic and pulmonary vasculature of the rattlesnake, <Emphasis Type="Italic">Crotalus durissus terrificus</Emphasis>

The functional role of nitric oxide (NO) was investigated in the systemic and pulmonary circulations of the South American rattlesnake, Crotalus durissus terrificus. Bolus, intra-arterial injections of the NO donor, sodium nitroprusside (SNP) caused a significant systemic vasodilatation resulting in a reduction in systemic resistance (Rsys). This response was accompanied by a significant decrease in systemic pressure and a rise in systemic blood flow. Pulmonary resistance (Rpul) remained constant while pulmonary pressure (Ppul) and pulmonary blood flow (Qpul) decreased. Injection of L-Arginine (L-Arg) produced a similar response to SNP in the systemic circulation, inducing an immediate systemic vasodilatation, while Rpul was unaffected. Blockade of NO synthesis via the nitric oxide synthase inhibitor, L-NAME, did not affect haemodynamic variables in the systemic circulation, indicating a small contribution of NO to the basal regulation of systemic vascular resistance. Similarly, Rpul and Qpul remained unchanged, although there was a significant rise in Ppul. Via injection of SNP, this study clearly demonstrates that NO causes a systemic vasodilatation in the rattlesnake, indicating that NO may contribute in the regulation of systemic vascular resistance. In contrast, the pulmonary vasculature seems far less responsive to NO.     

Studying Human Pathogens in Animal Models: Fine Tuning the Humanized Mouse

Humanized mice are crucial tools for studying human pathogens in systemic situations. An animal model of human coronavirus infectious disease has been generated by gene transfer of the human receptor for virus-cell interaction (aminopeptidase N, APN, CD13) into mice. We showed that in vitro and in vivo infections across the species barrier differ in their requirements. Transgenic cells were susceptible to human coronavirus HCoV-229E infection demonstrating the requirement of hAPN for viral cell entry. Transgenic mice, however, could not be infected suggesting additional requirements for in vivo virus susceptibility. Crossing hAPN transgenic mice with interferon unresponsive Stat1^−/− mice resulted in markedly enhanced virus replication in vitro but did not result in detectable virus replication in vivo. Adaptation of the human virus to murine cells led to successful infection of the humanized transgenic mice. Future genetic engineering approaches are suggested to provide animal models for the better understanding of human infectious diseases.     

14-Methylpentadecano-15-lactone (muscolide): a new macrocyclic lactone from the oil of Angelica archangelica L

The chemical composition of seed and root oils from Angelica archangelica L. was investigated. Analyses were performed by GC/MS and GC using two columns of different polarities (polyethylene glycol (DB-Wax) and 5% phenyl/95% polydimethylsiloxane (HP-5)), for the separation of several co-eluting components. A total of 58 compounds were identified, accounting for 96.3% (seed) and 93.5% (root) of the oils, respectively. A high content of beta-phellandrene (74.7%) was found in Angelica seed oil. Root oil contained a larger amount of macrocyclic lactones (1.3%) in comparison to the seed oil (0.4%). Different harvest dates produced only slight changes in the root-oil composition. In root oil harvested in summer, the beta-phellandrene content increased by ca. 36%, but no significant changes in the relative compositions of other components were observed. Fresh root oils were collected in five fractions (constant time intervals) during steam distillation (see Table). The highest-boiling fraction contained 9.3% of macrocyclic lactones such as tridecano-13-lactone (5.0%), 12-methyltridecano-13-lactone (0.4%), tetradecano-14-lactone (0.1%), pentadecano-15-lactone (3.5%), 14-methylpentadecano-15-lactone (1; trace), hexadecano-16-lactone (trace), and heptadecano-17-lactone (0.2%). This is the first report of the occurrence of 14-methylpentadecano-15-lactone (muscolide; 1) in a natural product.     

A completely foreign receptor can mediate an interferon-gamma-like response

A tripartite receptor comprising the external region of the erythropoietin (Epo) receptor, the transmembrane and JAK-binding domains of the gp130 subunit of the interleukin-6 (IL-6) receptor, and a seven amino acid STAT1 recruitment motif (Y440) from the interferon (IFN)-gamma receptor, efficiently mediates an IFN-gamma-like response. An analogous completely foreign chimeric receptor in which the Y440 motif is replaced with the Y905 motif from gp130 also mediates an IFN-gamma-like response, but less efficiently. The IFNGR1 signal-transducing subunit of the IFN-gamma receptor is tyrosine phosphorylated through the chimeric receptors and the endogenous IL-6 and OSM receptors. Cross phosphorylation of IFNGR1 is not, however, required for the IFN-gamma-like response through the chimeric receptors, nor does it mediate an IFN-gamma-like response to IL-6 or OSM. The data argue strongly for modular JAK/STAT signalling and against any rigid structural organization for the "pathways" involved. They emphasize the likely high degree of overlap between the signals generated from disparate JAK-receptor complexes and show that relatively minor changes in such complexes can profoundly affect the response.     

Flora des Etna

Ohne Zusammenfassung     

Cambial growth dynamics and climatic control of different tree life forms in tropical mountain forest in Ethiopia

Munessa Forest is a mountain forest in south-eastern Ethiopia experiencing seasonal rainfall variation. We investigated seasonal cambial activity and dormancy from increment rates of four different tree species belonging to varying life forms, namely, evergreen native conifer (Podocarpus falcatus), evergreen introduced conifer (Pinus patula), evergreen broadleaved tree (Prunus africana) and deciduous broadleaved tree (Celtis africana). Measurements of stem radius fluctuations were registered with the help of high-resolution electronic dendrometers. Daily amplitudes of stem diameter variations and daily and monthly net growth rates were determined and related to climatic variables measured at local climate stations. Thin sections of wood collected with a microcorer every 3–6 weeks allowed a visual control of newly formed wood cells during consecutive time intervals. Lack of water availability during the long dry season induced cambial dormancy of 5–7 months depending on life forms. After the onset of the short rainy season, stem swelling started quite synchronously with a variation of only single days in all studied species. Evergreen tree species were able to initiate wood formation during the short rainy season, whereas growth in the deciduous broadleaved species started in the long rainy season. The acquired data provide a basis for delineating the species-specific growth boundaries and the duration of the cambial growing season.     

Evaluation of five antischizophrenic agents against Toxoplasma gondii in human cell cultures

An increasing interest in the association of the presence of antibodies to Toxoplasma gondii and the development of schizophrenia in patients has been generated over the last several years. Some antischizophrenia agents have been shown to have activity against T. gondii in cell culture assays and to ameliorate behavioral changes associated with chronic T. gondii infection in rats. In the present study, we examined the effects of commonly used antipsychotic and mood stabilizing agents (haloperidol, clozapine, fluphenazine, trifluoperazine, and thioridazine) for activity against developing tachyzoites of the RH strain of T. gondii in human fibroblast cell cultures. Neither haloperidol nor clozapine had a measurable effect. Fluphenazine had an IC(50) of 1.7 μM, thioridazine had an IC(50) of 1.2 μM, and trifluoperazine had an IC(50) of 3.8 μM. Our study demonstrates that some agents used to treat schizophrenia have the ability to inhibit T. gondii proliferation in cell culture.     

Reversible inhibition of murine cytomegalovirus replication by gamma interferon (IFN-γ) in primary macrophages involves a primed type I IFN-signaling subnetwork for full establishment of an immediate-early antiviral state

Activated macrophages play a central role in controlling inflammatory responses to infection and are tightly regulated to rapidly mount responses to infectious challenge. Type I interferon (alpha/beta interferon [IFN-α/β]) and type II interferon (IFN-γ) play a crucial role in activating macrophages and subsequently restricting viral infections. Both types of IFNs signal through related but distinct signaling pathways, inducing a vast number of interferon-stimulated genes that are overlapping but distinguishable. The exact mechanism by which IFNs, particularly IFN-γ, inhibit DNA viruses such as cytomegalovirus (CMV) is still not fully understood. Here, we investigate the antiviral state developed in macrophages upon reversible inhibition of murine CMV by IFN-γ. On the basis of molecular profiling of the reversible inhibition, we identify a significant contribution of a restricted type I IFN subnetwork linked with IFN-γ activation. Genetic knockout of the type I-signaling pathway, in the context of IFN-γ stimulation, revealed an essential requirement for a primed type I-signaling process in developing a full refractory state in macrophages. A minimal transient induction of IFN-β upon macrophage activation with IFN-γ is also detectable. In dose and kinetic viral replication inhibition experiments with IFN-γ, the establishment of an antiviral effect is demonstrated to occur within the first hours of infection. We show that the inhibitory mechanisms at these very early times involve a blockade of the viral major immediate-early promoter activity. Altogether our results show that a primed type I IFN subnetwork contributes to an immediate-early antiviral state induced by type II IFN activation of macrophages, with a potential further amplification loop contributed by transient induction of IFN-β.