Publications by authors named "Scott Leonard"

Article Synopsis
  • The study investigates how microgravity and galactic cosmic rays (GCRs) influence behavioral performance and metabolic pathways in male Fischer rats, highlighting a gap in previous research regarding control conditions for hindlimb unloading (HU).
  • Male rats were subjected to total body irradiation and HU conditions, with plasma and brain tissue analyzed after 6 months to assess long-term metabolic changes.
  • Results showed significant interactions between radiation and HU, with various metabolic pathways affected in the plasma and brain, indicating complex interactions between stressors that could impact spaceflight crew health.
View Article and Find Full Text PDF

The unpredictable biodegradation of fluorotelomer (FT)-based per- and polyfluoroalkyl substances (PFAS) causes complicated risk management of PFAS-impacted sites. Here, we have successfully used redundancy analysis to link FT-based precursor biodegradation to key microbes and genes of soil microbiomes shaped by different classes of carbon sources: alcohols (C2-C4), alkanes (C6 and C8), an aromatic compound (phenol), or a hydrocarbon surfactant (cocamidopropyl betaine [CPB]). All the enrichments defluorinated fluorotelomer alcohols (:2 FtOH; = 4, 6, 8) effectively and grew on 6:2 fluorotelomer sulfonate (6:2 FtS) as a sulfur source.

View Article and Find Full Text PDF

Per- and polyfluoroalkyl substances (PFAS) are a widespread and persistent class of contaminants posing significant environmental and human health concerns. Comprehensive understanding of the modes of action underlying toxicity among structurally diverse PFAS is mostly lacking. To address this need, we recently reported on our application of developing zebrafish to evaluate a large library of PFAS for developmental toxicity.

View Article and Find Full Text PDF

The space environment astronauts experience during space missions consists of multiple environmental challenges, including microgravity. In this study, we assessed the behavioral and cognitive performances of male Fisher rats 2 months after sham irradiation or total body irradiation with photons in the absence or presence of simulated microgravity. We analyzed the plasma collected 9 months after sham irradiation or total body irradiation for distinct alterations in metabolic pathways and to determine whether changes to metabolic measures were associated with specific behavioral and cognitive measures.

View Article and Find Full Text PDF
Article Synopsis
  • Muscle wasting in aging zebrafish may be linked to oxidative stress from vitamin E deficiency, impacting their skeletal muscle health.
  • A study lasted from 55 days to 18 months, comparing zebrafish on diets with and without vitamin E, using advanced metabolomics techniques for analysis.
  • Results indicated that both aging and vitamin E deficiency uniquely affect metabolic pathways, with some overlaps, while highlighting the need for further research to confirm these findings.
View Article and Find Full Text PDF

Background: Numerous abnormalities in cystic fibrosis (CF) could influence tocopherol absorption, transportation, storage, metabolism and excretion. We hypothesized that the oxidative distress due to inflammation in CF increases vitamin E utilization, which could be positively influenced by supplemental vitamin C administration.

Methods: Immediately before and after receiving vitamin C (500 mg) twice daily for 3.

View Article and Find Full Text PDF

Although vitamin E acetate (VEA) is suspected to play a causal role in the development of electronic-cigarette, or vaping, product use-associated lung injury (EVALI), the underlying biological mechanisms of pulmonary injury are yet to be determined. In addition, no study has replicated the systemic inflammation observed in humans in a murine EVALI model, nor investigated potential additive toxicity of viral infection in the setting of exposure to vaping products. To identify the mechanisms driving VEA-related lung injury and test the hypothesis that viral infection causes additive lung injury in the presence of aerosolized VEA, we exposed mice to aerosolized VEA for extended times, followed by influenza infection in some experiments.

View Article and Find Full Text PDF

Triplex gene editing relies on binding a stable peptide nucleic acid (PNA) sequence to a chromosomal target, which alters the helical structure of DNA to stimulate site-specific recombination with a single-strand DNA (ssDNA) donor template and elicits gene correction. Here, we assessed whether the codelivery of PNA and donor template encapsulated in Poly Lactic-co-Glycolic Acid (PLGA)-based nanoparticles can correct sickle cell disease and x-linked severe combined immunodeficiency. However, through this process we have identified a false-positive PCR artifact due to the intrinsic capability of PNAs to aggregate with ssDNA donor templates.

View Article and Find Full Text PDF

A limitation of simulated space radiation studies is that radiation exposure is not the only environmental challenge astronauts face during missions. Therefore, we characterized behavioral and cognitive performance of male WAG/Rij rats 3 months after sham-irradiation or total body irradiation with a simplified 5-ion mixed beam exposure in the absence or presence of simulated weightlessness using hindlimb unloading (HU) alone. Six months following behavioral and cognitive testing or 9 months following sham-irradiation or total body irradiation, plasma and brain tissues (hippocampus and cortex) were processed to determine whether the behavioral and cognitive effects were associated with long-term alterations in metabolic pathways in plasma and brain.

View Article and Find Full Text PDF
Article Synopsis
  • The polyphenol xanthohumol (XN) improves glucose and lipid metabolism in animals with diet-induced obesity, and its effects are believed to depend on the gut microbiota.
  • A study tested XN on conventional and germ-free mice with different diets, revealing that XN reduces insulin levels and improves insulin resistance in conventional mice but has no effect in germ-free mice.
  • XN alters gut microbiota composition and is metabolized into bioactive compounds, indicating that the intestinal microbiota plays a crucial role in XN's benefits, prompting further research into its complex interactions with diet and host.
View Article and Find Full Text PDF
Article Synopsis
  • The XP-D/DinG family of DNA helicases, including YoaA from E. coli, plays a crucial role in maintaining genomic stability across all life forms, particularly by aiding in DNA repair and assisting in tolerance to inhibitors like AZT.
  • YoaA interacts with the DNA polymerase III component HolC, and this interaction appears to inhibit HolC's normal function, as YoaA's overexpression leads to growth inhibition in E. coli.
  • The expression of YoaA is regulated by the LexA protein and responds to DNA damage conditions, with its induction being influenced by the cell's growth phase and nutritional state, suggesting a complex relationship between DNA replication and repair mechanisms
View Article and Find Full Text PDF
Article Synopsis
  • - The study examined how vitamin E deficiency affects the expression of alpha-tocopherol transfer protein and related genes in zebrafish livers, based on the idea that low vitamin E would lead to higher lipid peroxidation.
  • - Fish were divided into two groups: one received a diet sufficient in vitamin E and the other a deficient diet for 9 months, leading to a significant increase in α-tocopherol and a decrease in malondialdehyde in the E+ group compared to the E- group.
  • - While the gene expression of ttpa remained unchanged, two other genes, ptpn9a and chka, were significantly upregulated in E- livers, indicating that vitamin E deficiency can
View Article and Find Full Text PDF
Article Synopsis
  • 3,3'-Diindolylmethane (DIM) is a compound found in cruciferous vegetables that has potential cancer-preventive properties and is used as a dietary supplement.
  • A study involving seven participants showed that after taking DIM capsules for a week, not only parent DIM but also several metabolites were detected in their plasma and urine, which contrasts with previous findings that only identified the parent compound.
  • One of the metabolites, identified as 3-((1-indole-3-yl)methyl)indolin-2-one, showed increased effectiveness as an aryl hydrocarbon receptor agonist, suggesting that DIM's metabolites may also have significant biological activity that requires further investigation.
View Article and Find Full Text PDF

Extracts of red clover ( L.), containing estrogenic isoflavones like genistein and daidzein and the proestrogenic isoflavones formononetin and biochanin A, are used by women as dietary supplements for the management of menopausal symptoms. Although marketed as a safer alternative to hormone therapy, red clover isoflavones have been reported to inhibit some cytochrome P450 (CYP) enzymes involved in drug metabolism.

View Article and Find Full Text PDF
Article Synopsis
  • - Vitamin E (VitE) is essential for fetal development, and its deficiency leads to increased lipid peroxidation and disrupts biochemical pathways necessary for maintaining glutathione (GSH) levels during embryogenesis.
  • - In a study comparing embryos with sufficient (E+) and deficient (E-) VitE, researchers found that betaine levels were significantly higher in E- embryos, and various amino acids and thiol compounds showed notable changes at different developmental stages.
  • - The results highlight the complex interplay between methyl donors and the methionine cycle in supporting thiol homeostasis, indicating potential dysregulation in the metabolic processes affecting embryo development due to VitE deficiency.
View Article and Find Full Text PDF
Article Synopsis
  • Vitamin E catabolism, specifically α-tocopherol, is essential for regulating body levels of this nutrient.
  • A study with healthy women used two labeled forms of α-tocopherol to examine how fat intake or fasting impacts its breakdown in the intestine and liver.
  • Results showed that the liver plays a major role in catabolism during fat intake, while fasting reduces liver contribution to α-tocopherol breakdown, indicating that both the intestine and liver are involved in this process.
View Article and Find Full Text PDF

Objective: All respiratory care represents some risk of becoming an aerosol-generating procedure (AGP) during COVID-19 patient management. Personal protective equipment (PPE) and environmental control/engineering is advised. High velocity nasal insufflation (HVNI) and high flow nasal cannula (HFNC) deliver high flow oxygen (HFO) therapy, established as a competent means of supporting oxygenation for acute respiratory distress patients, including that precipitated by COVID-19.

View Article and Find Full Text PDF

Older adults are at increased risk for vitamin and mineral deficiencies that contribute to age-related immune system decline. Several lines of evidence suggest that taking a multi-vitamin and mineral supplement (MVM) could improve immune function in individuals 55 and older. To test this hypothesis, we provided healthy older adults with either an MVM supplement formulated to improve immune function (Redoxon VI, Singapore) or an identical, inactive placebo control to take daily for 12 weeks.

View Article and Find Full Text PDF

Background: Determining the human vitamin E [α-tocopherol (α-T)] requirement is difficult, and novel approaches to assess α-T absorption and trafficking are needed.

Objective: We hypothesized that the dual-isotope technique, using 2 deuterium-labeled [intravenous (IV) d6- and oral d3-] α-T, would be effective in determining α-T fractional absorption. Further, defined liquid meal (DLM) fat or fasting would modulate α-T fractional absorption and lipoprotein transport.

View Article and Find Full Text PDF

To determine optimal conditions for blood collection during clinical trials, where sample handling logistics might preclude prompt separation of erythrocytes from plasma, healthy subjects (n=8, 6 M/2F) were recruited and non-fasting blood samples were collected into tubes containing different anticoagulants (ethylenediaminetetra-acetic acid (EDTA), Li-heparin or Na-heparin). We hypothesized that heparin, but not EDTA, would effectively protect plasma tocopherols, ascorbic acid, and vitamin E catabolites (α- and γ-CEHC) from oxidative damage. To test this hypothesis, one set of tubes was processed immediately and plasma samples were stored at -80°C, while the other set was stored at 4°C and processed the following morning (~30 hours) and analyzed, or the samples were analyzed after 6 months of storage.

View Article and Find Full Text PDF

Background: Inadequate vitamin E and magnesium intakes are of concern for older adults owing to the associated incidence of age-related diseases.

Objective: This study was designed to determine the extent to which a 16-wk intervention with hazelnuts alters vitamin E and magnesium status in a group of older men and women, and used a pre-post intervention design without a control group to adjust for temporal changes.

Methods: Participants (n = 32 including 22 women; mean ± SD age: 63 ± 6 y) consumed hazelnuts (∼57 g/d) for 16 wk.

View Article and Find Full Text PDF

High levels of alpha-tocopherol, the usual vitamin E supplement, are reported to decrease bone mass in rodents; however, the effects of other vitamin E forms on the skeleton are unknown. To test the hypothesis that high intakes of various vitamin E forms or the vitamin E metabolite, carboxyethyl hydroxy chromanol, were detrimental to bone status, Sprague-Dawley rats (n = 6 per group, 11-week males) for 18 weeks consumed semipurified diets that contained adequate alpha-tocopherol, high alpha-tocopherol (500 mg/kg diet), or 50% Tocomin (250 mg mixed tocopherols and tocotrienols/kg diet). Vitamin E status was evaluated by measuring plasma, liver, and bone marrow vitamin E concentrations.

View Article and Find Full Text PDF

Electric conductivity in plasma is the balance between oxidized and reduced molecules (static Oxidation-Reduction Potential, sORP) and the amount of readily oxidizable molecules (capacity ORP, cORP). Adults with metabolic syndrome (MetS) have increased inflammation, dyslipidemia and oxidative stress; therefore, participants with MetS were hypothesized to have higher plasma sORP and lower cORP than those measures in healthy adults. Heparin-anticoagulated plasma from healthy and age- and gender-matched individuals with MetS (BMI: 22.

View Article and Find Full Text PDF