Population‐based analysis of health care contacts among suicide decedents: identifying opportunities for more targeted suicide prevention strategies

The objective of this study was to detail the nature and correlates of mental health and non‐mental health care contacts prior to suicide death. We conducted a systematic extraction of data from records at the Office of the Chief Coroner of Ontario of each person who died by suicide in the city of Toronto from 1998 to 2011. Data on 2,835 suicide deaths were linked with provincial health administrative data to identify health care contacts during the 12 months prior to suicide. Sub‐populations of suicide decedents based on the presence and type of mental health care contact were described and compared across socio‐demographic, clinical and suicide‐specific variables. Time periods from last mental health contact to date of death were calculated and a Cox proportional hazards model examined covariates. Among suicide decedents, 91.7% had some type of past‐year health care contact prior to death, 66.4% had a mental health care contact, and 25.3% had only non‐mental health contacts. The most common type of mental health contact was an outpatient primary care visit (54.0%), followed by an outpatient psychiatric visit (39.8%), an emergency department visit (31.1%), and a psychiatric hospitalization (21.0%). The median time from last mental health contact to death was 18 days (interquartile range 5‐63). Mental health contact was significantly associated with female gender, age 25‐64, absence of a psychosocial stressor, diagnosis of schizophrenia or bipolar disorder, past suicide attempt, self‐poisoning method and absence of a suicide note. Significant differences between sub‐populations of suicide decedents based on the presence and nature of their health care contacts suggest the need for targeting of community and clinical‐based suicide prevention strategies. The predominance of ambulatory mental health care contacts, often close to the time of death, reinforce the importance of concentrating efforts on embedding risk assessment and care pathways into all routine primary and specialty clinical care, and not only acute care settings.     

Gestational age‐dependent gene expression profiling of ATP‐binding cassette transporters in the healthy human placenta

The ATP‐binding cassette (ABC) transporters control placental transfer of several nutrients, steroids, immunological factors, chemicals, and drugs at the maternal‐fetal interface. We and others have demonstrated a gestational age‐dependent expression pattern of two ABC transporters, P‐glycoprotein and breast cancer resistance protein throughout pregnancy. However, no reports have comprehensively elucidated the expression pattern of all 50 ABC proteins, comparing first trimester and term human placentae. We hypothesized that placental ABC transporters are expressed in a gestational‐age dependent manner in normal human pregnancy. Using the TaqMan^® Human ABC Transporter Array, we assessed the mRNA expression of all 50 ABC transporters in first (first trimester, n = 8) and third trimester (term, n = 12) human placentae and validated the resulting expression of selected ABC transporters using qPCR, Western blot and immunohistochemistry. A distinct gene expression profile of 30 ABC transporters was observed comparing first trimester vs. term placentae. Using individual qPCR in selected genes, we validated the increased expression of ABCA1 (P < 0.01), ABCA6 (P < 0.001), ABCA9 (P < 0.001) and ABCC3 (P < 0.001), as well as the decreased expression of ABCB11 (P < 0.001) and ABCG4 (P < 0.01) with advancing gestation. One important lipid transporter, ABCA6, was selected to correlate protein abundance and characterize tissue localization. ABCA6 exhibited increased protein expression towards term and was predominantly localized to syncytiotrophoblast cells. In conclusion, expression patterns of placental ABC transporters change as a function of gestational age. These changes are likely fundamental to a healthy pregnancy given the critical role that these transporters play in the regulation of steroidogenesis, immunological responses, and placental barrier function and integrity.     

Synthesis and evaluation of 1,3,5-triazine derivatives as sunscreens useful to prevent skin cancer

The incidence of skin cancers such as non-melanoma skin cancer and malignant melanoma has increased in the last few years mainly because of chronic exposure to ultraviolet (UV) radiation. Sunscreens protect the skin against harmful UV radiations; however, some limitations of these products justify the discovery of new UV filters. Novel 1,3,5-triazine derivatives (12a-h) obtained by the optimization of prototype resveratrol were synthesized and characterized. All compounds exhibited sun protection factor (SPF) and UVA protection factor (UVAPF) in the range of 3–17 and 3–13, respectively. These values were superior to resveratrol and the UV filter ethylhexyl triazone (EHT) currently available on the market. In addition, all compounds demonstrated in vitro antioxidant activity and thermal stability with the decomposition at temperatures above 236 °C. In conclusion, the novel 1,3,5-triazine derivatives have emerged as new UV filters with antioxidant effect useful to prevent skin cancer.     

Steric hindrance controls pyridine nucleotide specificity of a flavin‐dependent NADH:quinone oxidoreductase

The crystal structure of the NADH:quinone oxidoreductase PA1024 has been solved in complex with NAD⁺ to 2.2 Å resolution. The nicotinamide C4 is 3.6 Å from the FMN N5 atom, with a suitable orientation for facile hydride transfer. NAD⁺ binds in a folded conformation at the interface of the TIM‐barrel domain and the extended domain of the enzyme. Comparison of the enzyme‐NAD⁺ structure with that of the ligand‐free enzyme revealed a different conformation of a short loop (75–86) that is part of the NAD⁺‐binding pocket. P78, P82, and P84 provide internal rigidity to the loop, whereas Q80 serves as an active site latch that secures the NAD⁺ within the binding pocket. An interrupted helix consisting of two α‐helices connected by a small three‐residue loop binds the pyrophosphate moiety of NAD⁺. The adenine moiety of NAD⁺ appears to π–π stack with Y261. Steric constraints between the adenosine ribose of NAD⁺, P78, and Q80, control the strict specificity of the enzyme for NADH. Charged residues do not play a role in the specificity of PA1024 for the NADH substrate.     

Unravelling the interactions of the environmental host Acanthamoeba castellanii with fungi through the recognition by mannose‐binding proteins

Free‐living amoebae (FLAs) are major reservoirs for a variety of bacteria, viruses, and fungi. The most studied mycophagic FLA, Acanthamoeba castellanii (Ac), is a potential environmental host for endemic fungal pathogens such as Cryptococcus spp., Histoplasma capsulatum, Blastomyces dermatitides, and Sporothrix schenckii. However, the mechanisms involved in this interaction are poorly understood. The aim of this work was to characterize the molecular instances that enable Ac to interact with and ingest fungal pathogens, a process that could lead to selection and maintenance of possible virulence factors. The interaction of Ac with a variety of fungal pathogens was analysed in a multifactorial evaluation that included the role of multiplicity of infection over time. Fungal binding to Ac surface by living image consisted of a quick process, and fungal initial extrusion (vomocytosis) was detected from 15 to 80 min depending on the organism. When these fungi were cocultured with the amoeba, only Candida albicans and Cryptococcus neoformans were able to grow, whereas Paracoccidioides brasiliensis and Sporothrix brasiliensis displayed unchanged viability. Yeasts of H. capsulatum and Saccharomyces cerevisiae were rapidly killed by Ac; however, some cells remained viable after 48 hr. To evaluate changes in fungal virulence upon cocultivation with Ac, recovered yeasts were used to infect Galleria mellonella, and in all instances, they killed the larvae faster than control yeasts. Surface biotinylated extracts of Ac exhibited intense fungal binding by FACS and fluorescence microscopy. Binding was also intense to mannose, and mass spectrometry identified Ac proteins with affinity to fungal surfaces including two putative transmembrane mannose‐binding proteins (MBP, L8WXW7 and MBP1, Q6J288). Consistent with interactions with such mannose‐binding proteins, Ac–fungi interactions were inhibited by mannose. These MBPs may be involved in fungal recognition by amoeba and promotes interactions that allow the emergence and maintenance of fungal virulence for animals.     

Community of small mammals along an elevational gradient in Biological Reserve of Serra do Japi,municipality of Jundiaí‐SP,Brazil

Studies of elevational gradients in forests are particularly interesting for the considerable differences that can be observed over short distances, such as in vegetation and temperature. Different taxonomic groups display varying types of distribution patterns along elevational gradients, with unimodal distribution being recognised as the most common pattern. The distribution of species can be affected by a range of factors that include, biotic, spatial, climatic, historic and energetic. Small mammals represent an ideal model for studies about distribution and habitat use as they can be highly abundant, tend to have different diets and use space differently. The aims of this study are to build a comprehensive understanding of the community of small mammals of the Biological Reserve of Serra do Japi and to explore its distribution pattern along elevational gradients. We investigated the influence of biomass of arthropods, fruits and seeds and percentage of ground cover, canopy cover and vertical vegetation at richness and abundance of small mammals at three different elevations. To accomplish this, we used seventy‐two pitfall traps of 63 L to capture small mammals and distributed them equally across three elevations defined as low (880–899 m), intermediate (1046–1089 m) and high (1170–1189 m). Each elevation had three lines or replicas of traps. Throughout the study, we captured one hundred and fourteen individuals belonging to eleven species of small mammals. The presence of rare and endemic species demonstrates the importance of conservation and maintenance of the Biological Reserve of Serra do Japi. In regard to the distribution of species, despite the short gradient range, we found a unimodal pattern and a positive correlation between ground cover (fallen twigs and branches up to 1 m high) and richness and abundance of small mammals. More ground cover can reduce the effects of competition and predation on small mammals’ communities. Abstract in Portuguese is available with online material.     

Habitat use of the ocelot (Leopardus pardalis) in Brazilian Amazon

Amazonia forest plays a major role in providing ecosystem services for human and sanctuaries for wildlife. However, ongoing deforestation and habitat fragmentation in the Brazilian Amazon has threatened both. The ocelot is an ecologically important mesopredator and a potential conservation ambassador species, yet there are no previous studies on its habitat preference and spatial patterns in this biome. From 2010 to 2017, twelve sites were surveyed, totaling 899 camera trap stations, the largest known dataset for this species. Using occupancy modeling incorporating spatial autocorrelation, we assessed habitat use for ocelot populations across the Brazilian Amazon. Our results revealed a positive sigmoidal correlation between remote‐sensing derived metrics of forest cover, disjunct core area density, elevation, distance to roads, distance to settlements and habitat use, and that habitat use by ocelots was negatively associated with slope and distance to river/lake. These findings shed light on the regional scale habitat use of ocelots and indicate important species–habitat relationships, thus providing valuable information for conservation management and land‐use planning.     

Leaf Decomposition in a Dry Season Irrigation Experiment in Eastern Amazonian Forest Regrowth

Leaf-litter decomposition is a major component of carbon and nutrient dynamics in tropical forest ecosystems, and moisture availability is widely considered to be a major influence on decomposition rates. Here, we report the results of a study of leaf-litter decomposition of five tree species in response to dry-season irrigation in a tropical forest regrowth stand in the Brazilian Amazon; three experiments differing in the timing of installation and duration allowed for an improved resolution of irrigation effects on decomposition. We hypothesized that decomposition rates would be faster under higher moisture availability in the wet season and during dry-season irrigation periods in the treatment plots, and that decomposition rates would be faster for species with higher quality leaves, independent of treatment. The rates of decomposition ( k ) were up to 2.4 times higher in irrigated plots than in control plots. The highest k values were shown by Annona paludosa (0.97 to 1.26/yr) while Ocotea guianensis (0.73 to 0.85/yr) had the lowest values; intermediate rates were found for Lacistema pubescens (0.91 to 1.02/yr) and Vismia guianensis (0.91 to 1.08/yr). These four tree species differed significantly in leaf-litter quality parameters (nitrogen, phosphorus, lignin, and cellulose concentrations, as well as lignin:nitrogen and carbon:nitrogen ratios), but differences in decomposition rates among tree species were not strictly correlated with leaf-litter quality. Overall, our results show that dry-season moisture deficits limit decomposition in Amazonian forest regrowth.