Physiological constraints dictate toxin spatial heterogeneity in snake venom glands

Background: Venoms are ecological innovations that have evolved numerous times, on each occasion accompanied by the co-evolution of specialised morphological and behavioural characters for venom production and delivery. The close evolutionary interdependence between these characters is exemplified by animals that control the composition of their secreted venom. This ability depends in part on the production of different toxins in different locations of the venom gland, which was recently documented in venomous snakes. Here, we test the hypothesis that the distinct spatial distributions of toxins in snake venom glands are an adaptation that enables the secretion of venoms with distinct ecological functions. Results: We show that the main defensive and predatory peptide toxins are produced in distinct regions of the venom glands of the black-necked spitting cobra (Naja nigricollis), but these distributions likely reflect developmental effects. Indeed, we detected no significant differences in venom collected via defensive ‘spitting’ or predatory ‘biting’ events from the same specimens representing multiple lineages of spitting cobra. We also found the same spatial distribution of toxins in a non-spitting cobra and show that heterogeneous toxin distribution is a feature shared with a viper with primarily predatory venom. Conclusions: Our findings suggest that heterogeneous distributions of toxins are not an adaptation to controlling venom composition in snakes. Instead, it likely reflects physiological constraints on toxin production by the venom glands, opening avenues for future research on the mechanisms of functional differentiation of populations of protein-secreting cells within adaptive contexts

The medical threat of mamba envenoming in sub-Saharan Africa revealed by genus-wide analysis of venom composition, toxicity and antivenomics profiling of available antivenoms

Mambas (genus Dendroaspis) are among the most feared of the medically important elapid snakes found in sub-Saharan Africa, but many facets of their biology, including the diversity of venom composition, remain relatively understudied. Here, we present a reconstruction of mamba phylogeny, alongside genus-wide venom gland transcriptomic and high-resolution top-down venomic analyses. Whereas the green mambas, D. viridis, D. angusticeps, D. j. jamesoni and D. j. kaimosae, express 3FTx-predominant venoms, black mamba (D. polylepis) venom is dominated by dendrotoxins I and K. The divergent terrestrial ecology of D. polylepis compared to the arboreal niche occupied by all other mambas makes it plausible that this major difference in venom composition is due to dietary variation. The pattern of intrageneric venom variability across Dendroaspis represented a valuable opportunity to investigate, in a genus-wide context, the variant toxicity of the venom, and the degree of paraspecific cross-reactivity between antivenoms and mamba venoms. To this end, the immunological profiles of the five mamba venoms were assessed against a panel of commercial antivenoms generated for the sub-Saharan Africa market. This study provides a genus-wide overview of which available antivenoms may be more efficacious in neutralising human envenomings caused by mambas, irrespective of the species responsible. The information gathered in this study lays the foundations for rationalising the notably different potency and pharmacological profiles of Dendroaspis venoms at locus resolution. This understanding will allow selection and design of toxin immunogens with a view to generating a safer and more efficacious pan-specific antivenom against any mamba envenomation

The medical threat of mamba envenoming in sub-Saharan Africa revealed by genus-wide analysis of venom composition, toxicity and antivenomics profiling of available antivenoms

Mambas (genus Dendroaspis) are among the most feared of the medically important elapid snakes found in sub-Saharan Africa, but many facets of their biology, including the diversity of venom composition, remain relatively understudied. Here, we present a reconstruction of mamba phylogeny, alongside genus-wide venom gland transcriptomic and high-resolution top-down venomic analyses. Whereas the green mambas, D. viridis, D. angusticeps, D. j. jamesoni and D. j. kaimosae, express 3FTx-predominant venoms, black mamba (D. polylepis) venom is dominated by dendrotoxins I and K. The divergent terrestrial ecology of D. polylepis compared to the arboreal niche occupied by all other mambas makes it plausible that this major difference in venom composition is due to dietary variation. The pattern of intrageneric venom variability across Dendroaspis represented a valuable opportunity to investigate, in a genus-wide context, the variant toxicity of the venom, and the degree of paraspecific cross-reactivity between antivenoms and mamba venoms. To this end, the immunological profiles of the five mamba venoms were assessed against a panel of commercial antivenoms generated for the sub-Saharan Africa market. This study provides a genus-wide overview of which available antivenoms may be more efficacious in neutralising human envenomings caused by mambas, irrespective of the species responsible. The information gathered in this study lays the foundations for rationalising the notably different potency and pharmacological profiles of Dendroaspis venoms at locus resolution. This understanding will allow selection and design of toxin immunogens with a view to generating a safer and more efficacious pan-specific antivenom against any mamba envenomation

The World Health Organization Performance Assessment Tool for Quality Improvement in Hospitals (PATH): an analysis of the pilot implementation in 37 hospitals.

OBJECTIVE: To evaluate the pilot implementation of the World Health Organization Performance Assessment Tool for Quality Improvement in hospitals (PATH). DESIGN: Semi-structured interviews with regional/country coordinators and Internet-based survey distributed to hospital coordinators. SETTING: A total of 37 hospitals in six regions/countries (Belgium, Ontario (Canada), Denmark, France, Slovakia, KwaZulu Natal (South Africa)). PARTICIPANTS: Six PATH regional/country coordinators and 37 PATH hospital coordinators. INTERVENTION: Implementation of a hospital performance assessment pilot project. OUTCOME MEASURE: Experience of regional/country coordinators (structured interviews) and experience of hospital coordinators (survey) with the pilot implementation. RESULTS: The main achievement has been the collection and analysis of data on a set of indicators for comprehensive performance assessment in hospitals in regions and countries with different cultures and resource availability. Both regional/country coordinators and hospital coordinators required seed funding and technical support during data collection for implementation. Based on the user evaluation, we identified the following research and development tasks: further standardization and improved validity of indicators, increased use of routine data, more timely feedback with a stronger focus on international benchmarking and further support on interpretation of results. CONCLUSIONS: Key to successful implementation was the embedding of PATH in existing performance measurement initiatives while acknowledging the core objective of the project as a self-improvement tool. The pilot test raised a number of organizational and methodological challenges in the design and implementation of international research on hospital performance assessment. Moreover, the process of evaluating PATH resulted in interesting learning points for other existing and newly emerging quality indicator projects

The role of high-dose melphalan with autologous stem-cell transplant in multiple myeloma: is it time for a paradigm shift?

Recent advances in multiple myeloma include numerous approvals of novel therapies with unprecedented efficacy, a rapid and sustained tempo of new drug development, and further refinements to prognostication to include minimal residual disease (MRD) testing and improved risk stratification. The upfront use of immunomodulatory drug and proteasome inhibitor combinations followed by maintenance has resulted in transformative clinical benefit. Four-drug regimens incorporating monoclonal antibodies are reporting unprecedented rates of complete response and MRD negativity in the absence of intensification. In the context of these advances, the added value of high-dose melphalan with autologous stem-cell transplant (HDM-ASCT) is a key question. From a safety standpoint, HDM-ASCT is associated with both acute toxicities that reduce quality of life and long-term toxicities that may limit life expectancy for some patients. The present review discusses the recent advances in induction therapy, the impact of these advances on HDM-ASCT, the evolving role of MRD testing and the short- and long-term risks of HDM-ASCT. Recognising that prospective data remains limited, we suggest that HDM-ASCT not be considered mandatory for eligible newly diagnosed patients who are treated with highly efficacious regimens and achieve deep responses, but rather be held in reserve without early exposure to the clinical and genomic toxicity inherent to this approach

Benefit-Risk Summary of Nivolumab for Patients With Metastatic Squamous Cell Lung Cancer After Platinum-Based Chemotherapy

Metastatic squamous non-small-cell lung cancer (SQ NSCLC) is a serious and life-threatening malignant condition with unmet medical need. In late December 2014, the US Food and Drug Administration (FDA) obtained the data monitoring committee report of a planned interim analysis of a trial in second-line SQ NSCLC (CM017) that demonstrated an overall survival benefit for patients treated with nivolumab compared with docetaxel. In that trial, 272 patients with metastatic SQ NSCLC patients had been randomized to receive nivolumab (n = 135) or docetaxel (n = 137). Median overall survival was 9.2 months for patients randomized to nivolumab and 6.0 months for those randomized to docetaxel (hazard ratio, 0.59; 95% CI, 0.44-0.79; P < .001). The safety of nivolumab was evaluated in a single-arm trial of 117 patients in previously treated metastatic SQ NSCLC and was consistent with the safety profile in melanoma, with rare but serious immune-mediated adverse events managed with corticosteroids and dose interruption. The FDA granted nivolumab traditional approval on March 4, 2015, for treatment of metastatic SQ NSCLC with progression during or after platinum-based chemotherapy. The approval provides an important treatment option for these patients, affecting routine care and clinical trials