Mapping of clinical management resources for snakebites and other animal envenomings in the Brazilian Amazon

Snakebite envenomings (SBEs) and other envenomings triggered by venomous animals (VAEs) represent a significant disease burden in Brazil, with 29,152 SBEs reported in 2021 alone with nearly half of those occurring in the remote Brazilian Amazon. In 2021, Brazil recorded 240,294 envenomings from snakes, scorpions, spiders, and caterpillars. Therefore, there is an unequal distribution of SBEs with high morbidity and mortality in the Brazilian Amazon. The severity of SBEs increases when patients require more than 6 h to access antivenom treatment, a common issue for the rural and indigenous populations. Understanding currently available resources and practices in Amazon remote areas of Brazil can serve to inform future interventions and guide health care policies. This study aims to develop a resource map of existing healthcare resources for the Brazilian Amazon's clinical management of VAEs with emphasis in SBEs, which will aid future strategic interventions. Data collection included a literature review, secondary data collected by government departments and organizational records, GIS mapping activities, and expert input. Our framework was guided by the three levels of healthcare service ecosystem analysis (macro, meso, and micro). Our resource map lays out a comprehensive overview of antivenom access, the distribution landscape, differences in patient transportation, and barriers to access healthcare that face populations in the Brazilian Amazon.

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In Brazil, there are financial, cultural, and logistical barriers to access antivenom.

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Despite antivenom manufacturing on a national scale, antivenom treatment is limited in rural areas.

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Indigenous and riverine populations are the most vulnerable to being deprived of proper treatment.

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We present a framework guided by the macro, meso, and micro levels of healthcare service.

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Antivenom treatment decentralization should be a priority of the health system in the Brazilian Amazon.

In vitro evaluation of calphostin C as a novel agent for photodynamic therapy of bladder cancer

OBJECTIVES

Calphostin C, a highly specific protein kinase C inhibitor, induces apoptosis in the presence of visible light. We report the photoactivatable cytotoxicity of calphostin C in a series of well-characterized human bladder cancer cell lines: RT4, UM-UC-3, and 5637.

METHODS

The human bladder cancer cell lines RT4, UM-UC-3, and 5637 were chosen on the basis of their p53, pRb and 9p21 deletion status. Using standard tissue culture techniques, the cytotoxicity of 10 to 100 nM calphostin C in combination with increasing exposures of visible light was examined. Controls consisted of cells treated with calphostin C without visible light and cells exposed to visible light without calphostin C treatment. Cell viability was determined by MTT assay. The induction of apoptosis by activated calphostin C was determined by 4,6-diamidino-2-phenylindole (DAPI) staining/fluorescence microscopy of nuclei.

RESULTS

In the absence of light, calphostin C did not demonstrate a cytotoxic effect on any of the cell lines tested. Increasing the duration of light exposure resulted in a concomitant decrease in cell viability. Significant cell death was seen with calphostin C concentrations as low as 10 nM. These studies also demonstrated that calphostin C induced apoptosis by a mechanism independent of p53 and pRb status and the presence or absence of 9p21 deletions.

CONCLUSIONS

We demonstrated the ability of activated calphostin C to induce apoptosis in a light-dependent and concentration-dependent fashion in a bladder cancer model system. Activated calphostin C cytotoxicity is independent of tumor genetic background and the status of p53 and pRb. Further development of calphostin C as a photosensitizer for photodynamic therapy of superficial bladder cancer may be warranted.

Activated calphostin C cytotoxicity is independent of p53 status and in vivo metastatic potential

The development of novel therapeutic agents to modulate programmed cell death independent of genetic background or malignant potential is a primary goal of modern cancer therapy. In this report, the light activation- and concentration-dependent cytotoxicity of calphostin C, a photoactivatable perylenequinone, is carefully evaluated using a series of nine well-characterized human and rodent prostate cancer cell lines representing the spectrum of disease progression (e.g., variations in metastatic ability, ploidy, and tumor suppressor gene status). Treatment of these cancer cell lines with nanomolar concentrations of calphostin C in combination with increasing amounts of light exposure established a relationship between light and dose dependence of calphostin C cytotoxicity. The induction of apoptosis is rapid, as evidenced by the fact that immediately after treatment, cells exposed to calphostin C with light activation exhibit both morphological and biochemical changes consistent with apoptosis (cellular and nuclear shrinkage and chromatin condensation). For example, 78% of cells treated with 100 nM calphostin C in combination with 2 h of light activation underwent apoptosis within 24 h of treatment. DNA ladder formation could be detected within 12 h of treatment. In the absence of light activation, treatment with calphostin C at all concentrations tested had no acute or durable cytotoxic effects in any of the cell lines. Our findings demonstrate that calphostin C cytotoxicity is strictly light dependent. Furthermore, its efficacy is independent of the genetic background, p53 status, or in vivo malignant potential of a cell, making it a suitable candidate for the treatment of heterogeneous tumor cell populations.

Characterization of maturation and function of natural killer cells in xenogeneic (rat-->mouse) bone marrow chimeras. Evidence that rat NK cells are present and functional in a xenogeneic environment

Reconstitution of B10 recipient mice, conditioned with total body irradiation (950 rads), with 40 x 10(6) untreated F344 or WF rat bone marrow cells results in stable rat stem-cell engraftment with multilineage lymphohematopoietic chimerism. We have now characterized NK cell generation, maturation, and function in fully xenogeneic chimeras (WF rat-->B10 mouse; F344-->B10 mouse). Early during xenogeneic reconstitution, rat-derived NK cells predominated in splenic lymphoid tissue, composing 14-18% of total cells at week 1 and increasing to 35.6-59.9% of total cells at week 2. By week 6, levels of rat NK cells had decreased and stabilized to that expected for normal rat (9-14.2%). The NK chimerism was reliably stable for up to 7 months following reconstitution. Most importantly, rat-derived NK cells were functional in both YAC tumor cytolysis and ADCC assays, suggesting that the xenogeneic mouse host environment was sufficient to support the generation, maturation, and function of rat-derived NK cells.