Immunostimulation and Immunoinhibition of Premalignant Lesions

BACKGROUND: The immune reaction may be either stimulatory or inhibitory to tumor growth, depending upon the local ratio of immune reactants to tumor cells. HYPOTHESIS: A tumor-stimulatory immune response may be essential for survival of a neoplasm in vivo and for the biological progression from a premalignant lesion to a malignancy. Neither a positive nor a negative correlation between the magnitude of an immune-cell infiltrate and a cancer's prognosis can reveal whether the infiltrate was stimulating or inhibiting to the tumor's growth unless the position on the nonlinear curve that relates tumor growth to the magnitude of the immune reaction is known. DISCUSSION: This hypothesis is discussed in relation to the development of human malignant melanomas and colorectal cancers

A Spatio-Temporal Analysis of Matrix Protein and Nucleocapsid Trafficking during Vesicular Stomatitis Virus Uncoating

To study VSV entry and the fate of incoming matrix (M) protein during virus uncoating we used recombinant viruses encoding M proteins with a C-terminal tetracysteine tag that could be fluorescently labeled using biarsenical (Lumio) compounds. We found that uncoating occurs early in the endocytic pathway and is inhibited by expression of dominant-negative (DN) Rab5, but is not inhibited by DN-Rab7 or DN-Rab11. Uncoating, as defined by the separation of nucleocapsids from M protein, occurred between 15 and 20 minutes post-entry and did not require microtubules or an intact actin cytoskeleton. Unexpectedly, the bulk of M protein remained associated with endosomal membranes after uncoating and was eventually trafficked to recycling endosomes. Another small, but significant fraction of M distributed to nuclear pore complexes, which was also not dependent on microtubules or polymerized actin. Quantification of fluorescence from high-resolution confocal micrographs indicated that after membrane fusion, M protein diffuses across the endosomal membrane with a concomitant increase in fluorescence from the Lumio label which occurred soon after the release of RNPs into the cytoplasm. These data support a new model for VSV uncoating in which RNPs are released from M which remains bound to the endosomal membrane rather than the dissociation of M protein from RNPs after release of the complex into the cytoplasm following membrane fusion

Synchronized Retrovirus Fusion in Cells Expressing Alternative Receptor Isoforms Releases the Viral Core into Distinct Sub-cellular Compartments

Disparate enveloped viruses initiate infection by fusing with endosomes. However, the highly diverse and dynamic nature of endosomes impairs mechanistic studies of fusion and identification of sub-cellular sites supporting the nucleocapsid release. We took advantage of the extreme stability of avian retrovirus-receptor complexes at neutral pH and of acid-dependence of virus-endosome fusion to isolate the latter step from preceding asynchronous internalization/trafficking steps. Viruses were trapped within endosomes in the presence of NH4Cl. Removal of NH4Cl resulted in a quick and uniform acidification of all subcellular compartments, thereby initiating synchronous viral fusion. Single virus imaging demonstrated that fusion was initiated within seconds after acidification and often culminated in the release of the viral core from an endosome. Comparative studies of cells expressing either the transmembrane or GPI-anchored receptor isoform revealed that the transmembrane receptor delivered the virus to more fusion-permissive compartments. Thus the identity of endosomal compartments, in addition to their acidity, appears to modulate viral fusion. A more striking manifestation of the virus delivery to distinct compartments in the presence of NH4Cl was the viral core release into the cytosol of cells expressing the transmembrane receptor and into endosomes of cells expressing the GPI-anchored isoform. In the latter cells, the newly released cores exhibited restricted mobility and were exposed to a more acidic environment than the cytoplasm. These cores appear to enter into the cytosol after an additional slow temperature-dependent step. We conclude that the NH4Cl block traps the virus within intralumenal vesicles of late endosomes in cells expressing the GPI-anchored receptor. Viruses surrounded by more than one endosomal membrane release their core into the cytoplasm in two steps – fusion with an intralumenal vesicle followed by a yet unknown temperature-dependent step that liberates the core from late endosomes

IFITM3 Inhibits Influenza A Virus Infection by Preventing Cytosolic Entry

To replicate, viruses must gain access to the host cell's resources. Interferon (IFN) regulates the actions of a large complement of interferon effector genes (IEGs) that prevent viral replication. The interferon inducible transmembrane protein family members, IFITM1, 2 and 3, are IEGs required for inhibition of influenza A virus, dengue virus, and West Nile virus replication in vitro. Here we report that IFN prevents emergence of viral genomes from the endosomal pathway, and that IFITM3 is both necessary and sufficient for this function. Notably, viral pseudoparticles were inhibited from transferring their contents into the host cell cytosol by IFN, and IFITM3 was required and sufficient for this action. We further demonstrate that IFN expands Rab7 and LAMP1-containing structures, and that IFITM3 overexpression is sufficient for this phenotype. Moreover, IFITM3 partially resides in late endosomal and lysosomal structures, placing it in the path of invading viruses. Collectively our data are consistent with the prediction that viruses that fuse in the late endosomes or lysosomes are vulnerable to IFITM3's actions, while viruses that enter at the cell surface or in the early endosomes may avoid inhibition. Multiple viruses enter host cells through the late endocytic pathway, and many of these invaders are attenuated by IFN. Therefore these findings are likely to have significance for the intrinsic immune system's neutralization of a diverse array of threats

The Ethical Infrastructure of Legal Practice in Larger Law Firms: Values, Policy and Behaviour

The article examines the impact of the cultures and organisational structures of large law firms on individual lawyers' ethics. The paper suggests that large law firms in Australia should consciously design and implement 'ethical infrastructures' to both counteract pressures for misbehaviour and positively promote ethical behaviour and discussion. The paper goes on to explain what implementing ethical infrastructures in law firms could and should mean by reference to what Australian law firms are already doing and US innovations in this area. Finally, the paper warns that the 'ethical infrastructure' of a firm should not be seen merely as the formal ethics policies explicitly enunciated by management. Formal and legalistic ethical infrastructures that fail to support or encourage the development of individual lawyers' awareness oftheir own ethical values and ethical judgment in practice will be useless.Christine Parker, Adrian Evans, Linda Haller, Suzanne Le Mire And Reid Mortense

Melanomas in renal transplant recipients.

BACKGROUND: It is well documented that renal transplant recipients are at increased risk of developing skin cancers, in particular squamous cell carcinomas. Less extensively reviewed in the literature is the increased incidence of malignant melanoma. We have reviewed 10 patients in the Oxford renal transplant population who developed 12 melanomas following transplantation. OBJECTIVES: To determine the incidence and characteristics of melanoma in renal transplant recipients. METHODS: We reviewed the case notes and pathology of all patients who developed melanoma within the Oxford Renal Transplant Unit. The clinical details were recorded including date of transplant, immunosuppressive therapy, interval between transplant and melanoma, site of occurrence, history of sun exposure, type of clinician diagnosing the melanoma, history of other skin malignancies and outcome. From the histopathology we documented various prognostic factors. RESULTS: Ten patients developed 12 melanomas (one patient had three melanomas) from a population of 1874 transplanted patients. The total number of transplant years was 11 942.2. The incidence of melanoma in our population was 12 per 11 942.2 transplant years, which is approximately 8 times greater than the standardized rate for this region. We found that the mean interval between transplant and melanoma was approximately 11 years (median 8.5). A dermatologist was the diagnosing clinician in at least 67% of cases. Melanomas occurred on the trunk in the majority of cases (58%), followed by the upper limb (25%). All patients apart from one are alive with no recurrence of their melanoma. One patient died as a result of metastatic melanoma. The mean follow-up period following melanoma was 3.7 years. In all patients apart from the patient who died, the melanomas were < 1 mm Breslow thickness. That patient's melanoma was 4.5 mm thick. There was no precursor naevus in eight of the 12 melanomas. In two there was a precursor dysplastic naevus. In the cases in vertical growth phase the tumour-infiltrating lymphocyte response was absent in four cases and nonbrisk in one patient. CONCLUSIONS: In the Oxford transplant population studied melanomas occurred at approximately 8 times the rate in the general population. This is the highest rate reported in the literature. The patients had a better outcome than reported previously. This may be due to detection at a relatively early stage. Renal transplant recipients attend dedicated dermatology clinics in Oxford, which may have contributed to the early diagnosis and good outcome

Pollination insights for the conservation of a rare threatened plant species, Astragalus tragacantha (Fabaceae)

International audienceThe increase in habitat fragmentation impacts plant-pollinator interactions and threatens the sustainability of plant species. Astragalus tragacantha (Fabaceae), is a rare endangered plant species along the coastal habitats where the plant populations have undergone considerable fragmentation and decline of size. Controlled pollination treatments, the observation of pollinator activity, and pollinator captures, have been conducted to study: (1) the mating system of A. tragacantha and the potential for inbreeding depression and/or out-breeding depression based on controlled pollination treatments, (2) the pollinator composition among populations using a correspondence analysis and a hierarchical clustering, and (3) the link between pollinators and the plant reproductive success using a path-analysis model. In this study, we demonstrated that this plant was not autogamous self-pollinating and depended on pollinators for its reproduction. The absence of difference between manual and open pollinations regarding the reproductive success showed an absence of pollen limitation in our populations. We showed that populations differed in the composition of their pollinator guilds. Some pollinator species were predominant in certain populations. The pollination treatments revealed the existence of a mixed mating system in A. tragacan-tha populations. We showed an inbreeding depression potentially linked to a predominant pollinator-facilitated selfing, and the existence of outbreeding depression between some distant populations. These differences in pollinator guild and plant mating systems among populations must be considered during the restoration of populations along the Mediter-ranean coastal habitats in order to enhance the reproductive success and sustainability of A. tragacantha