Low salinity stress increases the risk of Vibrio parahaemolyticus infection and gut microbiota dysbiosis in Pacific white shrimp.

BACKGROUND: Extreme precipitation events often cause sudden drops in salinity, leading to disease outbreaks in shrimp aquaculture. Evidence suggests that environmental stress increases animal host susceptibility to pathogens. However, the mechanisms of how low salinity stress induces disease susceptibility remain poorly understood. METHODS: We investigated the acute response of shrimp gut microbiota exposed to pathogens under low salinity stress. For comparison, shrimp were exposed to Vibrio infection under two salinity conditions: optimal salinity (Control group) and low salinity stress (Stress group). High throughput 16S rRNA sequencing and real-time PCR were employed to characterize the shrimp gut microbiota and quantify the severity level of Vibrio infection. RESULTS: The results showed that low salinity stress increased Vibrio infection levels, reduced gut microbiota species richness, and perturbed microbial functions in the shrimp gut, leading to significant changes in lipopolysaccharide biosynthesis that promoted the growth of pathogens. Gut microbiota of the bacterial genera Candidatus Bacilliplasma, Cellvibrio, and Photobacterium were identified as biomarkers of the Stress group. The functions of the gut microbiota in the Stress group were primarily associated with cellular processes and the metabolism of lipid-related compounds. CONCLUSIONS: Our findings reveal how environmental stress, particularly low salinity, increases shrimp susceptibility to Vibrio infection by affecting the gut microbiota. This highlights the importance of avoiding low salinity stress and promoting gut microbiota resilience to maintain the health of shrimp.

Synergistic Polymer Blending Informs Efficient Terpolymer Design and Machine Learning Discerns Performance Trends for pDNA Delivery.

Cationic polymers offer an alternative to viral vectors in nucleic acid delivery. However, the development of polymer vehicles capable of high transfection efficiency and minimal toxicity has remained elusive, and continued exploration of the vast design space is required. Traditional single polymer syntheses with large monomer bases are very time-intensive, limiting the speed at which new formulations are identified. In this work, we present an experimental method for the quick probing of the design space, utilizing a combinatorial set of 90 polymer blends, derived from 6 statistical copolymers, to deliver pDNA. This workflow facilitated rapid screening of polyplex compositions, successfully tailoring polyplex hydrophobicity, particle size, and payload binding affinity. This workflow identified blended polyplexes with high levels of transfection efficiency and cell viability relative to single copolymer controls and commercial JetPEI, indicating synergistic benefits from copolymer blending. Polyplex composition was coupled with biological outputs to guide the synthesis of single terpolymer vehicles, with high-performing polymers P10 and M20, providing superior transfection of HEK293T cells in serum-free and serum-containing media, respectively. Machine learning coupled with SHapley Additive exPlanations (SHAP) was used to identify polymer/polyplex attributes that most impact transfection efficiency, viability, and overall effective efficiency. Subsequent transfections on ARPE-19 and HDFn cells found that P10 and M20 were surpassed in performance by M10, contrasting with results in HEK293T cells. This cell type dependency reinforced the need to evaluate transfection conditions with multiple cell models to potentially identify moieties more beneficial to delivery in certain tissues. Overall, the workflow employed can be used to expedite the exploration of the polymer design space, bypassing extensive synthesis, and to develop improved polymer delivery vehicles more readily for nucleic acid therapies.

Developing an agenda for the decolonization of global health.

Colonialism, which involves the systemic domination of lands, markets, peoples, assets, cultures or political institutions to exploit, misappropriate and extract wealth and resources, affects health in many ways. In recent years, interest has grown in the decolonization of global health with a focus on correcting power imbalances between high-income and low-income countries and on challenging ideas and values of some wealthy countries that shape the practice of global health. We argue that decolonization of global health must also address the relationship between global health actors and contemporary forms of colonialism, in particular the current forms of corporate and financialized colonialism that operate through globalized systems of wealth extraction and profiteering. We present a three-part agenda for action that can be taken to decolonize global health. The first part relates to the power asymmetries that exist between global health actors from high-income and historically privileged countries and their counterparts in low-income and marginalized settings. The second part concerns the colonization of the structures and systems of global health governance itself. The third part addresses how colonialism occurs through the global health system. Addressing all forms of colonialism calls for a political and economic anticolonialism as well as social decolonization aimed at ensuring greater national, racial, cultural and knowledge diversity within the structures of global health.

Le colonialisme, qui implique la domination systémique de terres, de marchés, de peuples, de ressources, de cultures ou d'institutions politiques dans le but d'exploiter, de détourner et d'extraire des richesses et des ressources, affecte la santé de nombreuses manières. Ces dernières années, la décolonisation de la santé mondiale a suscité un intérêt croissant, l'accent étant mis sur la correction des déséquilibres de pouvoir entre les pays à revenu élevé et les pays à faible revenu, ainsi que sur la remise en question des idées et des valeurs de certains pays riches qui façonnent la pratique de la santé mondiale. Nous soutenons que la décolonisation de la santé mondiale doit également aborder la relation entre les acteurs de la santé mondiale et les formes contemporaines de colonialisme, en particulier les formes actuelles de colonialisme d'entreprise et de colonialisme financiarisé qui opèrent par des systèmes mondialisés d'extraction de richesses et de profits. Nous présentons un programme d'action en trois parties destiné à décoloniser la santé mondiale. La première partie porte sur les asymétries de pouvoir existant entre les acteurs de la santé mondiale des pays à hauts revenus et historiquement privilégiés et leurs homologues des pays à faibles revenus et marginalisés. La deuxième partie concerne la colonisation des structures et des systèmes de la gouvernance mondiale de la santé elle-même. La troisième partie traite de la manière dont le colonialisme se manifeste à travers le système de santé mondial. La lutte contre toutes les formes de colonialisme nécessite un anticolonialisme politique et économique ainsi qu'une décolonisation sociale visant à garantir une plus grande diversité nationale, raciale, culturelle et des connaissances au sein des structures de la santé mondiale.

El colonialismo, que implica la dominación sistémica de tierras, mercados, pueblos, bienes, culturas o instituciones políticas para explotar, apropiarse indebidamente y extraer riqueza y recursos, afecta a la salud de muchas maneras. En los últimos años ha crecido el interés por descolonizar la salud mundial, en particular para corregir los desequilibrios de poder entre los países de ingresos altos y los de ingresos bajos, y para cuestionar las ideas y los valores de algunos países ricos que influyen en la práctica de la salud mundial. Sostenemos que la descolonización de la salud mundial también debe abordar la relación entre los actores de la salud mundial y las formas contemporáneas de colonialismo, en especial las formas actuales de colonialismo corporativo y financiarizado que operan a través de sistemas globalizados de extracción de riqueza y especulación. Presentamos un programa de acción dividido en tres partes para descolonizar la salud mundial. La primera parte se refiere a las asimetrías de poder que existen entre los actores de la salud mundial procedentes de países de ingresos altos e históricamente privilegiados y sus homólogos de entornos de ingresos bajos y marginados. La segunda parte se refiere a la colonización de las estructuras y sistemas de la propia gobernanza de la salud mundial. La tercera parte aborda cómo se produce el colonialismo a través del sistema sanitario mundial. Abordar todas las formas de colonialismo exige un anticolonialismo político y económico, así como una descolonización social destinada a garantizar una mayor diversidad nacional, racial, cultural y de conocimientos dentro de las estructuras de la salud mundial.

Shrimp SIRT4 promotes white spot syndrome virus replication.

In WSSV pathogenesis, the molecular mechanisms and the key host factors that regulate the viral replication and morphogenesis remain unclear. However, like most viruses, WSSV is known to induce metabolic reprogramming in several metabolic pathways including the host glutamine metabolism, and several recent reports have suggested that the sirtuins SIRT3, SIRT4, and SIRT5, which belong to a family of NAD+-dependent deacetylases, play an important role in this regulation. Here we focus on characterizing LvSIRT4 from Litopenaeus vannamei and investigate its role in regulating glutamine dehydrogenase (GDH), an important enzyme that promotes glutaminolysis and viral replication. We found that LvSIRT4 silencing led to significant decreases in both WSSV gene expression and the number of viral genome copies. Conversely, overexpression of LvSIRT4 led to significant increases in the expression of WSSV genes and the WSSV genome copy number. Immunostaining in Sf9 insect cells confirmed the presence of LvSIRT4 in the mitochondria and the co-localization of LvSIRT4 and LvGDH in the same cellular locations. In vivo gene silencing of LvSIRT4 significantly reduced the gene expression of LvGDH whereas LvSIRT4 overexpression had no effect. However, neither silencing nor overexpression had any effect on the protein expression levels of LvGDH. Lastly, although GDH activity in uninfected shrimp was unchanged, the GDH enzyme activity in WSSV-infected shrimp was significantly increased after both LvSIRT4 silencing and overexpression. This suggests that although there may be no direct regulation, LvSIRT4 might still be able to indirectly regulate LvGDH via the mediation of one or more WSSV proteins that have yet to be identified.

"Current", "heated rods", and "hot vapour": why patients refuse radiotherapy as a treatment modality for cancer in northern Sri Lanka.

PURPOSE: Significant proportions of patients either refuse or discontinue radiotherapy, even in the curative setting, leading to poor clinical outcomes. This study explores patient perceptions that underlie decisions to refuse/discontinue radiotherapy at a cancer care facility in northern Sri Lanka. METHODS: An exploratory descriptive qualitative study was carried out among 14 purposively selected patients with cancer who refused/discontinued radiotherapy. In-depth semi-structured interviews were transcribed in Tamil, translated into English, coded, and thematically analyzed. RESULTS: All participants referred to radiotherapy as "current" with several understanding the procedure to involve electricity, heat, or hot vapour. Many pointed to gaps in information provided by healthcare providers, who were perceived to focus on side effects without explaining the procedure. In the absence of these crucial details, patients relied on family members and acquaintances for information, often based on second or third-hand accounts of experiences with radiotherapy. Many felt pressured by family to refuse radiation, feared radiation, or felt ashamed to ask questions, while for others COVID-19 was an impediment. All but three participants regretted their decision, claiming they would recommend radiation to patients with cancer, especially when it is offered with curative intent. CONCLUSION: Patients with cancer who refused/discontinued radiation therapy have significant information needs. While human resource deficits need to be addressed in low-resource settings like northern Sri Lanka, providing better supportive cancer care could improve clinical outcomes and save healthcare resources that would otherwise be wasted on patient preparation for radiotherapy.

Decolonising global health research: Shifting power for transformative change.

Recent debates on decolonizing global health have spurred interest in addressing the power asymmetries and knowledge hierarchies that sustain colonial ideas and relationships in global health research. This paper applies three intersecting dimensions of colonialism (colonialism within global health; colonisation of global health; and colonialism through global health) to develop a broader and more structural understanding of the policies and actions needed to decolonise global health research. It argues that existing guidelines and checklists designed to make global health research more equitable do not adequately address the underlying power asymmetries and biases that prevail across the global health research ecosystem. Beyond encouraging fairer partnerships within individual research projects, this paper calls for more emphasis on shifting the balance of decision-making power, redistributing resources, and holding research funders and other power-holders accountable to the places and peoples involved in and impacted by global health research.

Poly(l-glutamic acid) augments the transfection performance of lipophilic polycations by overcoming tradeoffs among cytotoxicity, pDNA delivery efficiency, and serum stability.

Polycations are scalable and affordable nanocarriers for delivering therapeutic nucleic acids. Yet, cationicity-dependent tradeoffs between nucleic acid delivery efficiency, cytotoxicity, and serum stability hinder clinical translation. Typically, the most efficient polycationic vehicles also tend to be the most toxic. For lipophilic polycations-which recruit hydrophobic interactions in addition to electrostatic interactions to bind and deliver nucleic acids-extensive chemical or architectural modifications sometimes fail to resolve intractable toxicity-efficiency tradeoffs. Here, we employ a facile post-synthetic polyplex surface modification strategy wherein poly(l-glutamic acid) (PGA) rescues toxicity, inhibits hemolysis, and prevents serum inhibition of lipophilic polycation-mediated plasmid (pDNA) delivery. Importantly, the sequence in which polycations, pDNA, and PGA are combined dictates pDNA conformations and spatial distribution. Circular dichroism spectroscopy reveals that PGA must be added last to polyplexes assembled from lipophilic polycations and pDNA; else, PGA will disrupt polycation-mediated pDNA condensation. Although PGA did not mitigate toxicity caused by hydrophilic PEI-based polycations, PGA tripled the population of transfected viable cells for lipophilic polycations. Non-specific adsorption of serum proteins abrogated pDNA delivery mediated by lipophilic polycations; however, PGA-coated polyplexes proved more serum-tolerant than uncoated polyplexes. Despite lower cellular uptake than uncoated polyplexes, PGA-coated polyplexes were imported into nuclei at higher rates. PGA also silenced the hemolytic activity of lipophilic polycations. Our work provides fundamental insights into how polyanionic coatings such as PGA transform intermolecular interactions between lipophilic polycations, nucleic acids, and serum proteins, and facilitate gentle yet efficient transgene delivery.

Mortality among persons with tuberculosis in Zambian hospitals: A retrospective cohort study.

Tuberculosis (TB) mortality in Zambia remains high at 86 per 100,000 populations, translating to approximately 15,000 TB-related deaths annually. We conducted a nationwide retrospective cohort study to understand predictors, time to death, and probable causes of mortality among persons on TB treatment in Zambia. We reviewed medical records for persons with TB registered in 54 purposively selected hospitals in Zambia between January and December 2019. We fitted a Cox proportional hazards model to identify predictors of mortality. Of the 13,220 records abstracted, 10,987 were analyzed after excluding records of persons who transferred in from other hospitals, those with inconsistent dates and those whose treatment outcome was not evaluated. The majority of persons with TB were men, (61.5%, n = 6,761) with a median age of 36 years (IQR: 27-46 years). Overall, 1,063 (9.7%) died before completing TB treatment (incidence rate = 16.9 deaths per 1,000 person-months). Median age at death was 40 years (IQR: 31-52). The majority of deaths (75.7%, n = 799) occurred in the first two months of TB treatment, with a median time to death of 21 days (IQR: 6-57). Independent risk factors for TB mortality included age >54 years, being treated in Eastern, Southern, Western, Muchinga and Central provinces, receiving treatment from a third-level or mission hospital, methods of diagnosis other than Xpert MTB/RIF, extrapulmonary TB (EPTB), and positive HIV status. Probable causes of death were septic shock (18.8%), TB Immune Reconstitution Inflammatory Syndrome (TB IRIS) (17.8%), end-organ damage (13.4%), pulmonary TB (11.4%), anemia (9.6%) and TB meningitis (7.8%). These results show high mortality among people undergoing TB treatment in Zambia. Interventions targeted at persons most at risk such as the elderly, those with EPTB, and those living with HIV, can help reduce TB-related mortalities in Zambia.

Machine Learning Elucidates Design Features of Plasmid DNA Lipid Nanoparticles for Cell Type-Preferential Transfection.

For cell and gene therapies to become more broadly accessible, it is critical to develop and optimize non-viral cell type-preferential gene carriers such as lipid nanoparticles (LNPs). Despite the effectiveness of high throughput screening (HTS) approaches in expediting LNP discovery, they are often costly, labor-intensive, and often do not provide actionable LNP design rules that focus screening efforts on the most relevant chemical and formulation parameters. Here we employed a machine learning (ML) workflow using well-curated plasmid DNA LNP transfection datasets across six cell types to maximize chemical insights from HTS studies and has achieved predictions with 5-9% error on average depending on cell type. By applying Shapley additive explanations to our ML models, we unveiled composition-function relationships dictating cell type-preferential LNP transfection efficiency. Notably, we identified consistent LNP composition parameters that enhance in vitro transfection efficiency across diverse cell types, such as ionizable to helper lipid ratios near 1:1 or 10:1 and the incorporation of cationic/zwitterionic helper lipids. In addition, several parameters were found to modulate cell type-preferentiality, including the ionizable and helper lipid total molar percentage, N/P ratio, cholesterol to PEGylated lipid ratio, and the chemical identity of the helper lipid. This study leverages HTS of compositionally diverse LNP libraries and ML analysis to understand the interactions between lipid components in LNP formulations; and offers fundamental insights that contribute to the establishment of unique sets of LNP compositions tailored for cell type-preferential transfection.

Identification of a novel, MSC-induced macrophage subtype via single-cell sequencing: implications for intervertebral disc degeneration therapy.

Intervertebral disc (IVD) degeneration is a common pathological condition associated with low back pain. Recent evidence suggests that mesenchymal signaling cells (MSCs) promote IVD regeneration, but underlying mechanisms remain poorly defined. One postulated mechanism is via modulation of macrophage phenotypes. In this manuscript, we tested the hypothesis that MSCs produce trophic factors that alter macrophage subsets. To this end, we collected conditioned medium from human, bone marrow-derived STRO3+ MSCs. We then cultured human bone marrow-derived macrophages in MSC conditioned medium (CM) and performed single cell RNA-sequencing. Comparative analyses between macrophages cultured in hypoxic and normoxic MSC CM showed large overlap between macrophage subsets; however, we identified a unique hypoxic MSC CM-induced macrophage cluster. To determine if factors from MSC CM simulated effects of the anti-inflammatory cytokine IL-4, we integrated the data from macrophages cultured in hypoxic MSC CM with and without IL-4 addition. Integration of these data sets showed considerable overlap, demonstrating that hypoxic MSC CM simulates the effects of IL-4. Interestingly, macrophages cultured in normoxic MSC CM in the absence of IL-4 did not significantly contribute to the unique cluster within our comparison analyses and showed differential TGF-ß signaling; thus, normoxic conditions did not approximate IL-4. In addition, TGF-ß neutralization partially limited the effects of MSC CM. In conclusion, our study identified a unique macrophage subset induced by MSCs within hypoxic conditions and supports that MSCs alter macrophage phenotypes through TGF-ß-dependent mechanisms.