Contribution to unravel variability in bowhead whale songs and better understand its ecological significance.

Since the first studies on bowhead whale singing behaviour, song variations have been consistently reported. However, there has been little discussion regarding variability in bowhead whale singing display and its ecological significance. Unlike the better studied humpback whales, bowhead whales do not appear to share songs at population level, but several studies have reported song sharing within clusters of animals. Over the winter season 2013-2014, in an unstudied wintering ground off Northeast Greenland, 13 song groups sharing similar hierarchical structure and units were identified. Unit types were assessed through multidimensional maps, showing well separated clusters corresponding to manually labelled units, and revealing the presence of unit subtypes. Units presented contrasting levels of variability over their acoustic parameters, suggesting that bowhead whales keep consistency in some units while using a continuum in values of frequency, duration and modulation parameters for other unit types. Those findings emphasise the need to account for variability in song analysis to better understand the behavioural ecology of this endangered species. Additionally, shifting from song toward units or phrase-based analysis, as it has been suggested for humpback whales, offers the opportunity to identify and track similarities in songs over temporal and geographical scales relevant to population monitoring.

Activation of executioner caspases is a predictor of progression-free survival in glioblastoma patients: a systems medicine approach.

Glioblastoma (GBM) is the most common and aggressive primary brain tumor in adults. GBM cells are highly resistant to apoptosis induced by antitumor drugs and radiotherapy resulting in cancer progression. We assessed whether a systems medicine approach, analysing the ability of tumor cells to execute apoptosis could be utilized to predict the response of GBM patients to treatment. Concentrations of the key proapoptotic proteins procaspase-3, procaspase-9, Smac and Apaf-1 and the antiapopotic protein XIAP were determined in a panel of GBM cell lines and GBM patient tumor resections. These values were used as input for APOPTO-CELL, a systems biological based mathematical model built to predict cellular susceptibility to undergo caspase activation. The modeling was capable of accurately distinguishing between GBM cells that die or survive in response to treatment with temozolomide in 10 of the 11 lines analysed. Importantly the results obtained using GBM patient samples show that APOPTO-CELL was capable of stratifying patients according to their progression-free survival times and predicted the ability of tumor cells to support caspase activation in 16 of the 21 GBM patients analysed. Calculating the susceptibility to apoptosis execution may be a potent tool in predicting GBM patient therapy responsiveness and may allow for the use of APOPTO-CELL in a clinical setting.

Efficient systemic therapy of rat glioblastoma by nanoparticle-bound doxorubicin is due to antiangiogenic effects.

The objective of this study was to investigate the therapeutic effects of doxorubicin bound to polysorbate-coated nanoparticles that had previously been shown to significantly enhance survival in the orthotopic rat 101/8 glioblastoma model. Tumor-bearing animals were subjected to chemotherapy using doxorubicin in solution (Dox-sol) or doxorubicin bound to polysorbate 80-coated poly(butyl cyanoacrylate) nanoparticles (Dox-np) injected intravenously on Days 2, 5 and 8 post tumor implantation. The antitumor effect was assessed on Days 10, 14 and 18 post tumor implantation. Tumors showed signs of malignancy including invasion of brain tissue, brisk mitotic activity, microvascular proliferation, necrosis and increased proliferation resembling human glioblastoma. Dox-np produced a considerably more pronounced antitumor effect exhibited as a reduced tumor size, lower proliferation, and a decreased necrotic area compared to Dox-sol and to untreated control groups. A drastic effect of Dox-np on vascularization indicated an antiangiogenic mode of action.

5-aminolaevulinic acid photodynamic therapy in a transgenic mouse model of skin melanoma.

Photodynamic therapy (PDT) is widely used to treat preneoplastic skin lesions and non-melanoma skin tumours. Studies analyzing the effects of PDT on malignant melanoma have yielded conflicting results. On the one hand, melanoma cell lines in culture as well as cell lines transplanted into experimental animals were sensitive to PDT. On the other hand, spontaneous melanomas of human patients responded poorly to most PDT regimens tested so far. Here, we analyzed effects of 5-aminolaevulinic acid (5-ALA)-based PDT on melanoma cell lines and on experimental melanomas. To mimic the clinical situation as closely as possible, metallothionein-I/ret (MT-ret) mice, a transgenic model of skin melanoma development, were used. Optimal doses of 5-ALA as well as energy doses and power densities were determined in vitro using a cell line (Mel25) established by us from a melanoma of an MT-ret transgenic mouse as well as commercially available human and mouse melanoma cell lines. Treatment with light irradiation alone had no effect. In combination with 5-ALA, however, this illumination readily induced the death of all mouse and human melanoma cell lines examined. Still, 5-ALA PDT caused only minor focal regressive changes including haemorrhages and fibrosis of MT-ret melanomas in vivo and did not significantly delay tumour growth. These results show that, even though MT-ret melanoma cells are vulnerable to 5-ALA PDT in vitro, malignant MT-ret melanomas in vivo are quite resistant to this type of therapy at doses which are highly effective in vitro.

[Monophasic action potentials: considerations and limits]. / Potentiels d'action monophasiques: intérêts et limites.

Monophasic action potentials are currents recorded in vivo in the extracellular milieu which can reproduce the repolarisation signal of intracellular action potentials. For a long time unstable and complex to record, they now require simply a firm myocardial contact with a bipolar electrophysiological catheter and modification with recording filters, without a high-pass filter (DC). They have been widely used in recent years to study in vivo modifications of the action potential durations with frequency, epi-, endo-, or intramyocardial cellular topography, endocavity pressure modifications, or antiarrhythmic medication. They allow a unique means of continuous analysis in animals or in patients of the action potentials during polymorphic arrhythmias such as atrial fibrillation, ventricular fibrillation and torsades de pointes, although in these cases the refractory periods can not be measured precisely and continuously, beat after beat. In contrast, their clinical or experimental use in the study of arrhythmias dependent on premature post-depolarisations has without doubt been excessive and disputable, because it appears improbable that authentic premature post-depolarisations could ever be obtained on a monophasic action potential, which always represents the summation of the action potentials of dozens of cells.

Immunocytochemical localization of angiotensin II receptor subtypes and angiotensin II with monoclonal antibodies in the rat adrenal gland.

Angiotensin II (Ang II), a major regulator of cardiovascular function and body fluid homeostasis, mediates its biological actions via two subtypes of G protein-coupled receptors, termed AT(1) and AT(2). The primary goal of this study was to raise monoclonal anti-peptide antibodies specific to angiotensin AT(1)- and AT(2)-receptor subtypes and to Ang II itself and using these monoclonal antibodies to determine the intraadrenal localization of AT(1) and AT(2) receptors and Ang II in male adult rats. Immunocytochemistry unambiguously demonstrates a regional colocalization of Ang II and angiotensin II receptors in the adrenal gland. The novel antibodies localized Ang II and the AT(1) receptors to the zona glomerulosa of the cortex and to the medulla whereas AT(2) receptors were limited to the medulla. The specificity of immunostaining was documented by pre-adsorption of the antibody with the immunogenic peptide. Our data underscore that AT(1) appears to mediate most of the physiological actions of Ang II in adrenal. Western blot analysis of rat adrenal protein extracts using AT(1) antibody showed a predominant 73-kDa band and a weaker 97-kDa immunoreactive band corresponding to glycosylated forms of the AT(1) receptor. Immunostaining with anti-AT(2) yielded one major immunoreactive band of 73-kDa size and one additional fainter band of 120 kDa. These antibodies may prove of value in unraveling the subcellular localization and intracellular effector pathways of AT(1) and AT(2).

Astrocytic alterations in interleukin-6/Soluble interleukin-6 receptor alpha double-transgenic mice.

Interleukin-6 (IL-6), a major cytokine with diverse effects on cells mainly of the immune and hematopoietic systems, has been linked to several neurological disorders such as acquired immune deficiency syndrome dementia, multiple sclerosis, and Alzheimer's disease. Central nervous system (CNS)-specific expression of IL-6 caused neurodegeneration, massive gliosis, and vascular proliferation in transgenic mice. However, the effects of systemically circulating IL-6 and its receptor IL-6Ralpha on the CNS are unknown. IL-6Ralpha is the specific component of the IL-6 receptor system and hence an important co-factor of IL-6. IL-6Ralpha is bioactive in a membrane-bound and in a soluble (s) form. We investigated the effects of systemically elevated levels of either human IL-6 or human sIL-6Ralpha or both on the CNS of transgenic mice. Although IL-6 and sIL-6Ralpha single transgenic mice were free of neurological disease, IL-6/sIL-6Ralpha double-transgenic mice showed neurological signs, such as tremor, gait abnormalities, and paresis. However, these mice also frequently showed prominent general weakness probably because of the systemic effects of IL-6/IL-6Ralpha such as liver damage and plasmacytomas. IL-6/sIL-6Ralpha transgenic mice exhibited massive reactive gliosis. Lack of signs of neuronal breakdown versus ample astrogliosis suggested that astrocytes were selectively affected in these mice. There was neither vascular proliferation nor inflammatory infiltration. Ultrastructural analysis revealed blood-brain barrier (BBB) changes manifested by hydropic astrocytic end-feet. However, albumin immunohistochemistry did not reveal major BBB leakage. Our results indicate that increased and constitutive systemic expression of IL-6 together with its soluble receptor sIL-6Ralpha is less harmful to the brain than to other organs. The BBB remains primarily intact. IL-6/IL-6Ralpha, however, might be directly responsible for the selective activation of astrocytes.

Characterization of Tu-2449, a glioma cell line derived from a spontaneous tumor in GFAP-v-src-transgenic mice: comparison with established murine glioma cell lines.

Glial fibrillary acidic protein (GFAP)-v-src transgenic mice develop spontaneous gliomas with a high incidence of malignant progression. We characterize the first glial cell line derived from v-src transgenic mice, Tu-2449 in comparison with a virally induced murine glioma, SRB-10, and a spontaneous murine glioma, P497. Doubling times were lowest, as clonogenicity in soft agar was highest for Tu-2449, and to a lesser degree, Tu-2449 cells formed spheroids and showed migratory behaviour and invaded fetal rat brain aggregates. BCL-2 and BAX expression were lower in Tu-2449 and P497 than in SRB-10 cells. Only Tu-2449 cells accumulated p53 protein in response to genotoxic stress. Tu-2449 and SRB-10 cells that showed low CD95 expression were resistant to CD95 ligand (CD95L)-induced apoptosis unless coexposed to CD95L and inhibitors of RNA or protein synthesis. A chemosensitivity profile revealed Tu-2449 to be rather chemoresistant. Tu-2449 thus displays growth characteristics and patterns of resistance to apoptosis similar to those of other mouse and human glioma cell lines and may therefore become a valuable tool to evaluate new therapies for malignant gliomas in vitro and in vivo.

Early induction of angiogenetic signals in gliomas of GFAP-v-src transgenic mice.

Angiogenesis is a prerequisite for solid tumor growth. Glioblastoma multiforme, the most common malignant brain tumor, is characterized by extensive vascular proliferation. We previously showed that transgenic mice expressing a GFAP-v-src fusion gene in astrocytes develop low-grade astrocytomas that progressively evolve into hypervascularized glioblastomas. Here, we examined whether tumor progression triggers angiogenetic signals. We found abundant transcription of vascular endothelial growth factor (VEGF) in neoplastic astrocytes at surprisingly early stages of tumorigenesis. VEGF and v-src expression patterns were not identical, suggesting that VEGF activation was not only dependent on v-src. Late-stage gliomas showed perinecrotic VEGF up-regulation similarly to human glioblastoma. Expression patterns of the endothelial angiogenic receptors flt-1, flk-1, tie-1, and tie-2 were similar to those described in human gliomas, but flt-1 was expressed also in neoplastic astrocytes, suggesting an autocrine role in tumor growth. In crossbreeding experiments, hemizygous ablation of the tumor suppressor genes Rb and p53 had no significant effect on the expression of VEGF, flt-1, flk-1, tie-1, and tie-2. Therefore, expression of angiogenic signals is an early event during progression of GFAP-v-src tumors and precedes hypervascularization. Given the close similarities in the progression pattern between GFAP-v-src and human gliomas, the present results suggest that these mice may provide a useful tool for antiangiogenic therapy research.

Distinct phases of cryogenic tissue damage in the cerebral cortex of wild-type and c-fos deficient mice.

To characterize the development of tissue damage following cryogenic injury to the mouse cortex, the time course of histopathological changes, transcriptional responses and DNA strand breaks following application of a liquid nitrogen-cooled probe to the surface of the parietal bone were assessed. Distinct phases of tissue damage were observed: after 30 min, there was demarcation of a core lesion followed by mainly necrotic cell death starting 2 h after injury. At 12 hours, progressive apoptotic death of scattered cells in the periphery of the core lesion was detected, resembling the penumbra observed in ischaemic stroke. In situ hybridization for c-fos revealed an absence of expression in the core region, suggesting early cessation of transcription. There was strong induction of c-fos in the penumbra 30 min after the lesion, which had spread over the ipsilateral hemisphere at 2 h, possibly caused by peri-infarction depolarization. At later time points, sustained expression of c-fos was observed in some cells in the penumbra. Since a role for c-fos has been postulated in the initiation or execution of apoptotic pathways, the susceptibility of c-fos deficient mice was explored (n=4) in this model. Cryoinjury-induced tissue injury was markedly attenuated in c-fos deficient mice. A model of the phases and mechanisms of cryogenic injury is proposed, which discriminates an early phase characterized by physical changes caused by hypothermia and their immediate consequences (i.e. transcriptional block), an intermediate phase where secondary changes lead to necrosis in the core region, and a final phase of delayed apoptotic cell death in the penumbra.

Transgenic mice as research tools in neurocarcinogenesis.

Transgenic animal models for neurocarcinogenesis have provided significant insights into the molecular mechanisms underlying carcinogenic processes, including those which affect the nervous system. In view of the very rapid pace of acquisition of knowledge, it is not possible to cover all transgenic mouse models for neural tumors. Instead, this article discusses some of the most important technical innovations for manipulation of the mammalian genome (notably the various methods for targeted genome modifications, as well as the technology for introducing large DNA fragments into the germ line of mice), and presents a selection of the transgenic mouse models which are proving most promising for furthering our understanding of the pathogenetic basis of cancer in the nervous system.

Development and malignant progression of astrocytomas in GFAP-v-src transgenic mice.

We have generated a transgenic mouse model for astrocytoma by expressing the v-src kinase under control of the glial fibrillary acidic protein (GFAP) gene regulatory elements in astrocytes. Abnormal astrogliosis was observed in all transgenic animals already at 2 weeks postnatally, frequently followed by the development of dysplastic changes. Later, small proliferative foci arose, and overt astrocytoma developed in the brain and spinal cord in 14.4% of mice after a follow up time of 65 weeks. While early lesions were histologically consistent with low-grade astrocytoma, at later stages most tumors were highly mitotic and frankly malignant. Vascular endothelial growth factor (VEGF) was expressed by tumor cells already at early stages, suggesting induction by v-src, and it was most pronounced in pseudopalisading cells surrounding necrotic areas, implying additional upregulation by hypoxia. In larger lesions, mitotic activity and expression of flk-1, the cognate receptor of VEGF were induced in endothelial cells. Therefore, end-stage tumors mimicked the morphological and molecular characteristics of human glioblastoma multiforme. Time course and stochastic nature of the process indicate that v-src did not suffice for malignant transformation, and that astrocytomas were the result of a multistep process necessitating co-operation of additional genetic events.

Evidence for superantigen activity of the Bel 3 protein of the human foamy virus.

The human foamy virus is a complex retrovirus that codes for several regulatory bel genes in addition to the conventional gag, pol, and env genes. The bel 3 gene is located in the 3' part of the viral genome comparable to that of the superantigen of the mouse mammary tumor virus. Superantigens bound to major histocompatibility complex (MHC) class II molecules have been shown to stimulate T cells in a V beta-specific manner. The recombinant Bel 3 protein purified to near homogeneity was assayed in vitro to determine whether or not it functions as a superantigen that stimulates human T lymphocytes expressing particular V beta T cell receptor (TCR) chains. Therefore, an analysis including all known human V beta elements was performed. The expression of different V beta chains of the TCR was analyzed by reverse transcription of the V beta RNAs and subsequent amplification of the corresponding V beta cDNA elements by polymerase chain reaction in unstimulated, phytohemaggluttinin (PHA)- and Bel 3-stimulated human T lymphocytes. In addition, eight monoclonal antibodies directed against particular V beta family members were used to determine any change in the expression of the remaining known V beta elements upon treatment with PHA and Bel 3. The comparative V beta-specific transcriptional analysis revealed that the in vitro expression of the V beta 18 chain was specifically and strongly expanded in Bel 3-stimulated human T cells, a property characteristic for a superantigen.

Identification and characterization of the Bel 3 protein of human foamy virus.

The human foamy virus (HFV) is a complex retrovirus that contains several regulatory and auxiliary bel genes besides the gag, pol, and env genes. In contrast to the gene products of bel 1 and bel 2/bet that were identified previously, the Bel 3 protein has not been described to date. Here we report the identification of Bel 3 in HFV-infected cells by immunoprecipitation, indirect immunofluorescence, and expression cloning under the control of a strong heterologous promoter. Bel 3 was immunoprecipitated with an antiserum directed against a bacterially expressed and purified form of recombinant Bel 3 antigen. Bel 3 was found to be expressed in low amounts in the cytoplasm of HFV-infected cells and to migrate with an apparent molecular mass of 19.4 kDa on electrophoresis in SDS-polyacrylamide gels, consistent with the calculated value of 18.2 kDa. Radioimmunoprecipitation of HFV-infected cell lysates with the hyperimmune serum against Bel 3 revealed at least two additional immunoreactive bands of 15.5 and 10.6 kDa. The results indicate that Bel 3 was labile, because it was partially degraded even at early time points after infection. On transfection and expression in transfected COS cells, recombinant Bel 3 was immunoprecipitated and migrated in three polypeptide bands of 18.7, 14.8, and 9.3 kDa under denaturing conditions. In the absence of reducing agents, the bacterially expressed and purified recombinant Bel 3 protein of 16.1 kDa can form homodimers of 30 kDa.

[Soil fluoride: low digestive absorption in sheep]. / Fluor du sol: faible absorption digestive chez les ovins.

The percentages of digestive absorption of fluoride contained in various soils were assessed by the balance technique in groups of 4 ewes given soil enriched concentrated feed. Four soils collected in an area close to a source of fluoride and 3 samples from non polluted sites were used. The levels of extractable fluoride were significantly higher in the polluted soils. The various soils have little influence on the amounts of fluoride excreted in urine; these amounts are not correlated with the amounts of fluoride absorbed in the digestive tract. The percentages of digestive absorption of soil fluoride ranged between 4.5 and 23%, with 4 values close to 20%. The values are correlated with the soil total fluoride concentration and not with the soil extractable fluoride concentration.