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Kinetic variable-sample methods for stochastic optimization problems
(American Institute of Mathematical Sciences, 2025) Bonandin, Sabrina; Herty, Michael
We discuss kinetic-based particle optimization methods and variable-sample strategies for problems where the cost function represents the expected value of a random mapping. Kinetic-based optimization methods rely on a consensus mechanism targeting the global minimizer, and they exploit tools of kinetic theory to establish a rigorous framework for proving convergence to that minimizer. Variable-sample strategies replace the expected value by an approximation at each iteration of the optimization algorithm. We combine these approaches and introduce a novel algorithm based on instantaneous collisions governed by a linear Boltzmann-type equation. After proving the convergence of the resulting kinetic method under appropriate parameter constraints, we establish a connection to a recently introduced consensus-based method for solving the random problem in a suitable scaling. Finally, we showcase its enhanced computational efficiency compared to the aforementioned algorithm and validate the consistency of the proposed modeling approaches through several numerical experiments.
Molecular evidence of Brucella abortus circulating in cattle, goats, and humans in Central Equatoria State, South Sudan
(Nature Research, 2025-04) Lita, Emmanuel P.; Mkupasi, Ernatus M.; Ochi, Erneo B.; Misinzo, Gerald; Van Heerden, Henriette; Katani, Robab; Godfroid, Jacques; Mathew, Coletha
Brucellosis is a neglected zoonotic disease in most developing countries, including South Sudan. Precise identification of Brucella species is crucial for addressing public health and epidemiological concerns associated with brucellosis. The study aimed to identify Brucella species using real-time polymerase chain reaction (qPCR) from seropositive samples that were acquired from an earlier investigation. A total of 143 genomic DNA samples were extracted from brucellosis Rose Bengal plate test (RBPT) seropositive samples from humans (n = 7), cattle (n = 103) and goats (n = 33). The samples were collected from Terekeka and Juba counties, Central Equatoria State (CES), South Sudan. The qPCR targeting the Brucella-specific IS711 insertion gene at the genus level was performed. Samples with a cycle threshold (Ct) of ≤ 35 were considered positive and subjected to further Brucella speciation assays. Out of 143 DNA samples tested for genus-specific Brucella, 15 (10.5%) were positive including 4 (2.8%) from humans, 10 (6.9%) from cattle, and 1 (0.7%) from goats. Brucella abortus was identified in 5 (33.3%) of the positive samples at the genus level. The overall individual species infection rates with B. abortus were 6.6% (1/15) in humans, 20% (3/15) in cattle, and 6.6% (1/15) in goats. There was no B. melitensis detected in this study. This study identified B. abortus in cattle, goats and humans in CES, South Sudan. The findings suggest that cattle are probably the primary reservoirs for transmission of B. abortus, with infections occurring in goats and humans primarily resulting from cattle spillover.
Integrated profiling of adiponectin and cytokine signaling pathways in high-fat diet-induced MASLD reveals early markers of disease progression
(Nature Research, 2025-06) Johnson, Rabia; Shabalala, Samukelisiwe; Mabasa, Lawrence; Kotze-Hoerstmann, Liske; Sangweni, Nonhlakanipho; Ramharack, Pritika; Sharma, Jyoti; Pheiffer, Carmen; Arowolo, Afolake; Sadie-Van Gijsen, Hanel
Metabolic dysfunction-associated steatotic liver disease (MASLD), which affects a significant portion of the global population, is linked to high-fat diets (HFD) and characterized by abnormal lipid accumulation and activation of inflammatory pathways in hepatocytes. The precise mechanisms underlying MASLD, especially the involvement of inflammatory cytokines in its pathophysiology, remain unclear. This study evaluated the changes and interactions of steatotic liver and inflammatory markers in an animal model of MASLD by feeding male Wistar rats a high-fat diet (HFD) for 17 weeks. After this period, the serum lipid profiles were assessed, along with liver enzymes, including aspartate aminotransferase (AST) and alanine aminotransferase (ALT). The changes in liver morphology and triglyceride levels were determined by histology and a colorimetric assay, respectively. Steatotic liver and inflammatory markers were measured using a RT2 ProfilerTMPCRArray and validated with quantitative real-time PCR (qRT-PCR). Histological evaluations indicated that HFD livers exhibited macrovesicular steatosis and lobular inflammation. The HFD-fed group had significantly higher hepatic triglyceride levels than the controls (383 ± 23 mg/dL vs. 100 ± 9 mg/dL) and elevated serum lipid levels (p < 0.0001), along with increased liver aminotransferase levels. Gene expression analysis showed decreased adiponectin signaling (AdipoR2, p < 0.001) and upregulated de novo lipogenesis (Srebf1, p < 0.05). Notably, pro-inflammatory cytokines (Cxcl10, Ccl2, Ilβ, p < 0.001; TNF-α, p < 0.01) were significantly elevated, correlating with reduced hepatic glucose transporter Glut2 expression (p < 0.05), as confirmed by STRING analysis. These findings demonstrate that HFD consumption alters key genes and pathways involved in adiponectin and insulin signalling, lipogenesis, and inflammatory responses, thereby contributing to the pathogenesis of MASLD. Additionally, it identifies a comprehensive chemokine expression profile, highlighting potential therapeutic targets for MASLD.
Insights into the effects of geographical sourcing area on nutrient composition and sensory attributes of nine edible insects
(Nature Research, 2025-05) Ishara, Jackson; Matendo, Rehema; Ng'ang'a, Jeremiah; Niassy, Saliou; Katcho, Karume; Kinyuru, John
With the rapidly growing world population, climate change uncertainties and depletion of our natural resources, edible insects are seen as sustainable and viable bioresources for food and feed to tackle global food and nutritional security issues, for their nutritional value, taste, and environmental sustainability. In this study, we investigated the effect of geographical distribution on the nutrient composition and sensory attributes of commonly consumed edible insects, namely Acheta domesticus, Apis mellifera, Gnathocera trivittata, Gryllotalpa africana, Imbrasia oyemensis, Locusta migratoria, Macrotermes subhylanus, Nomadacris septemfasciata, and Rhyncophorus phoenicis collected from six different geographical areas namely Fizi, Kabare, Kalehe, Idjwi, Mwenge and Walungu, in the Eastern D. R. Congo. Depending on edible insect species, geographical sourcing area affected significantly macronutrient composition and mineral profile as well as sensory attributes of investigated commonly edible insects. A principal component analysis (PCA-Biplot) indicated that the two axes accounted for up to 97.7% of the observed variability in the nutrient composition and sensory attributes of commonly consumed edible insects sourced from different geographical area. Visualized results after cluster analysis using non-metric multidimensional scaling (NMDS) indicated that the geographical sourcing area has substantial and significant effect on the nutrient composition as well as sensory attributes of the studied commonly edible with a stress value of 0.185.
Genomic relatedness of colonizing and invasive disease Klebsiella pneumoniae isolates in South African infants
(Nature Research, 2025-03) Olwagen, Courtney P.; Izu, Alane; Khan, Shama; Van der Merwe, Lara; Dean, Nicholas J.; Mabena, Fikile C.; Jones, Stephanie; Kwatra, Gaurav; Andrew, Lubomira; Rajyaguru, Urvi; Donald, Robert G.K.; Simon, Raphael; Said, Mohamed; Nakwa, Firdose L.; Wadula, Jeannette; Strehlau, Renate; Van Niekerk, Anika M.; Naidoo, Niree; Ramsamy, Yogandree; Velaphi, Sithembiso C.; Dangor, Ziyaad; Madhi, Shabir A.
Klebsiella pneumoniae (KPn) colonizes multiple anatomical sites and is a leading cause of invasive disease and death in African children; however, there is no comparative genomic analysis between colonizing and invasive strains. This study investigated the genomic relatedness of KPn colonizing and invasive isolates in South African infants; and evaluated the relative invasiveness of KPn isolates based on sequence types (ST), capsular (KL), and lipopolysaccharide (O) loci by calculating case-carrier ratios (CCRs). There was less genomic diversity amongst invasive (22 ST, 17 K-loci) than colonizing isolates (31 ST, 29 K-loci), with invasive isolates being 8.59-fold and 3.49-fold more likely to harbour genes encoding for multi-drug resistance and yersiniabactin production compared with colonizing isolates. The CCRs for KL102 and O1/O2v2 were > 1, and < 1 for KL8, ST1414, and O1O2v1. Identifying high-risk strains, including KL102 and O1O2v2, that may have a higher potential to cause invasive disease, could enhance risk assessment and management strategies in vulnerable populations.