Publications by authors named "Zachary Keltner"

Carboxymethyl starches are added to food products for thickening or tablet binding/filling purposes. Although they lack toxicity, their synthesis creates the chemical byproduct diglycolic acid (DGA), which is difficult to eliminate and whose toxicity is in question. A rare case of an accidental direct exposure to extremely high concentrations of DGA in a person revealed that DGA has the potential to be toxic to several organs, with the kidneys and liver being the most affected organs.

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Phenolic compounds, like carvacrol, in oregano interfere with the detection of foodborne pathogens such as Salmonella enterica. Carvacrol concentration varies based on plant cultivars and growth region. Six oregano cultivars were used to compare the impact of carvacrol concentration on Salmonella and to evaluate the effectiveness of corn oil to help increase Salmonella survival for detection.

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In this study, the effects of surface charge, dose, and cosmetic vehicle on the penetration of silver nanoparticles (AgNPs) into pig and human skin were compared. AgNPs (20 nm) with varying surface-charges (polyethylene glycol (PEG; neutral), citrate (CIT; negative), and branched polyethylenimine (bPEI; positive) were dosed onto skin in in vitro diffusion cells using an aqueous solution and an oil-in-water emulsion formulation. Samples were analyzed by inductively coupled plasma mass spectroscopy (ICP-MS) and transmission electron microscope (TEM) to assess AgNP skin penetration.

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Diglycolic acid (DGA) is present in trace amounts in our food supply and is classified as an indirect food additive linked with the primary GRAS food additive carboxymethyl cellulose (CMC). Carboxymethyl starches are used as a filler/binder excipient in dietary supplement tablets and a thickening ingredient in many other processed foods. We sought to utilize the human proximal tubule HK-2 cell line as an cellular model system to evaluate its acute nephrotoxicity of DGA.

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Background: The widespread application of silver nanoparticles (AgNPs) and silver-containing products has raised public safety concerns about their adverse effects on human health and the environment. To date, in vitro toxic effects of AgNPs and ionic silver (Ag) on many somatic cell types are well established. However, no studies have been conducted hitherto to evaluate their effect on cellular transcriptome in embryonic stem cells (ESCs).

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The acute oral toxicity of diglycolic acid (DGA) was evaluated. Groups of female rats (n = 8 rats/group) received 28 consecutive daily single doses of 0.3, 1.

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Paenibacillus alvei, a naturally occurring soil microorganism, may be used in the control and/or elimination of human/animal pathogens present on/within produce commodities associated with human consumption. The safety of oral exposure to P. alvei in male, nulliparous females, the pregnant dam and developing fetus was assessed.

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Male and female rats (26-day old) were exposed to 0.0, 0.4, 4 or 40 mg/kg body weight silver acetate (AgAc) in drinking water for 10 weeks prior to and during mating.

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Effects of oral silver acetate exposure were assessed in P generation and F generation post-natal day 26 rats. Male and female Sprague Dawley rats (n = 20 each) were exposed to silver acetate at 0.4, 4.

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Male and female rats (26-day-old) were exposed to 0.0, 0.4, 4 or 40 mg/kg body weight silver acetate (AgAc) in drinking water for 10 weeks prior to and during mating.

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The in vivo toxicity to eukaryotes of nanosilver (AgNP) spheres and plates in two sizes each was assessed using the simple model organism . For each shape, smaller AgNP size correlated with higher toxicity, as indicated by reduced larval growth. Smaller size also correlated with significant increases in silver uptake for silver nanospheres.

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The industrial chemical melamine was used in 2007 and 2008 to raise the apparent protein content in pet feed and watered down milk, respectively. Because humans may be exposed to melamine via several different routes into the human diet as well as deliberate contamination, this study was designed to characterize the effect of high dose melamine or cyanuric acid oral exposure on the pregnant animal and developing fetus, including placental transfer. Clear rectangular crystals formed following a single triazine exposure which is a different morphology from the golden spherulites caused by combined exposure or the calculi formed when melamine combines with endogenous uric acid.

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Although standard nephrotoxicity assessments primarily detect impaired renal function, KIM-1, clusterin, NGAL, osteopontin and TIMP-1 were recently identified biomarkers proposed to indicate earlier perturbations in renal integrity. The recent adulteration of infant and pet food with melamine (MEL) and structurally-related compounds revealed that co-ingestion of MEL and cyanuric acid (CYA) could form melamine-cyanurate crystals which obstruct renal tubules and induce acute renal failure. This study concurrently evaluated the ability of multiplexed urinary biomarker immunoassays and biomarker gene expression analysis to detect nephrotoxicity in F344 rats co-administered 60ppm each of MEL and CYA in feed or via gavage for 28days.

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Effects of the dosing matrix and timing on the onset of renal crystal formation were evaluated in male and non-pregnant female rats (Fisher 344) exposed to both melamine (MEL) and cyanuric acid (CYA) for 28 days. Rats were fed ground feed containing 60 ppm MEL and 60 ppm CYA, (5 mg/kg bw/day equivalent), or exposed via oral gavage to carboxymethylcellulose containing 5 mg/kg bw MEL followed by 5 mg/kg bw CYA either consecutively (<1 min apart) or delayed 45 min after MEL. Staggered gavage exposure to MEL/CYA caused extensive renal crystal formation as compared to when the two compounds were administered consecutively or in feed.

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Numerous reports have demonstrated an active role for proinsulin C-peptide in ameliorating chronic complications associated with diabetes mellitus. It has been recently reported that some of these activities are dependent upon activation of C-peptide with certain metal ions, such as Fe(II), Cr(III) or Zn(II). In an effort to gain a greater understanding of the structure/function dependence of the peptide-metal interactions responsible for this activity, a series of experiments involving the use of electrospray ionization (ESI), matrix assisted laser desorption/ionization (MALDI) and collision-induced dissociation-tandem mass spectrometry (CID-MS/MS) of C-peptide in the presence or absence of Zn(II) have been carried out.

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Insulin resistance can broadly be defined as the diminished ability of cells to respond to the action of insulin in transporting glucose from the bloodstream into cells and tissues. Here, we report that erythrocytes (ERYs) obtained from type 2 diabetic rats display an apparent resistance to Zn(2+)-activated C-peptide. Thus, the aims of this study were to demonstrate that Zn(2+)-activated C-peptide exerts potentially beneficial effects on healthy ERYs and that these same effects on type 2 diabetic ERYs are enhanced in the presence of metformin.

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A comparison of prism-based spectrographs to grating-based spectrographs is made when each of the systems is coupled to a modern-day liquid-nitrogen-cooled photovoltaic array detector. A comparison of the systems is also made using a room-temperature microbolometer array detector. Finally, infrared microspectroscopy of samples whose size is approximately 10 micrometers will be demonstrated using a prism spectrograph outfitted with both types of detectors.

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