Use of urinary renal biomarkers to evaluate the nephrotoxic effects of melamine or cyanuric acid in non-pregnant and pregnant rats

Carbohydrate anchored lipid nanoparticles

Nanotechnology has been a dynamic field for formulation scientists with multidisciplinary research being conducted worldwide. Advancements in development of functional nanosystems have led to evolution of breakthrough technologies. Lipidic nanosystems, in particular, are highly preferred owing to their non-immunogenic safety profiles along with a range of versatile intrinsic properties. Surface modification of lipid nanoparticles by anchoring carbohydrates to these systems is one such attractive drug delivery technology. Carbohydrates confer interesting properties to the nanosystems such as stealth, biostability, bioavailability, reduced toxicity due to decreased immunogenic response, targeting potential as well as ease of commercial availability. The carbohydrate anchored systems can be developed using methods such as adsorption, incorporation (nanoprecipitation or solvent displacement method), crosslinking and grafting. Current review provides a detailed overview of potential lipid based nanoparticulate systems with an emphasis on liposomes, solid lipid nanoparticles, nanostructures lipid carriers and micelles. Review further explores basics of surface modification, methods applied therein, advantages of carbohydrates as surface modifiers, their versatile applications, techniques for characterization of carbohydrate anchored systems and vital regulatory aspects concerned with these specialized systems.

Evaluation of transporter expression in HK-2 cells after exposure to free and ester-bound 3-MCPD

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3-Monochloropropane-1,2-diol (3-MCPD) and its fatty acid esters have the potential to induce nephrotoxicity.

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We used an in vitro cellular model of human proximal tubule cells to test the effects of 3-MCPD compound exposures on transporter gene expression.

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3-MCPD-related nephrotoxicity could be associated with indirect modes of action relating to aquaporin homeostasis.

3-Monochloropropane-1,2-diol (3-MCPD) is a food processing contaminant in some infant formula products and other foods in the United States. Although rodent studies have demonstrated that 3-MCPD and its palmitic esters have the potential to induce nephrotoxicity, our recent human cell culture studies using the human renal proximal tubule cell line HK-2 have not strongly supported this finding. Considering this disparity, we sought to examine whether changes in transporter gene expression on proximal tubule cells could be modulated by these compounds and allow us to glean mechanistic information on a possible indirect path to proximal tubule injury in vivo. If fundamental processes like water and solute transport could be disrupted by 3-MCPD compounds, then a new avenue of toxicity could be further explored in both infant and adult models. In our current study, we used HK-2 cells as an in vitro cellular model of human proximal tubule cells to investigate the effects of low (10 μM) and high (100 μM) 3-MCPD compound exposures to these cells for 24 hours (h) on the expression of 20 transporter genes that are known to be relevant to proximal tubules. Although we detected consistent upregulation of AQP1 expression at the RNA transcript level following HK-2 treatment with both low and high doses of several ester-bound 3-MCPD compounds, these increases were not associated with statistically significant elevations in their protein expression levels. Moreover, we observed a lack of modulation of other members of the AQP protein family that are known to be expressed by human proximal tubule cells. Overall, our study suggests the possibility that 3-MCPD-related nephrotoxicity could be associated with indirect modes of action relating to aquaporin homeostasis, but additional studies with other human-derived models would be pertinent to further explore these findings and to better understand transporter expression differences under different stages of proximal tubule development.

Long-term in vitro effects of exposing the human HK-2 proximal tubule cell line to 3-monochloropropane-1,2-diol

3-Monochloropropane-1,2-diol (3-MCPD) is a food processing contaminant in the U.S. food supply, detected in infant formula. In vivo rodent model studies have identified a variety of possible adverse outcomes from 3-MCPD exposure including renal effects like increased kidney weights, tubular hyperplasia, kidney tubular necrosis, and chronic progressive nephropathy. Given the lack of available in vivo toxicological assessments of 3-MCPD in humans and the limited availability of in vitro human cell studies, the health effects of 3-MCPD remain unclear. We used in vitro human proximal tubule cells represented by the HK-2 cell line to compare short- and long-term consequences to continuous exposure to this compound. After periodic lengths of exposure (0-100 mM) ranging from 1 to 16 days, we evaluated cell viability, mitochondrial integrity, oxidative stress, and a specific biomarker of proximal tubule injury, Kidney Injury Molecule-1 (KIM-1). Overall, we found that free 3-MCPD was generally more toxic at high concentrations or extended durations of exposure, but that its overall ability to induce cell injury was limited in this in vitro system. Further experiments will be needed to conduct a comprehensive safety assessment in infants who may be exposed to 3-MCPD through consumption of infant formula, as human renal physiology changes significantly during development.

Environmental toxin-induced acute kidney injury

Human beings are exposed to various potentially toxic agents and conditions in their natural and occupational environments. The kidney, due to its concentrating ability and excretory function, is highly vulnerable to the effects of environmental toxins. Identifying the precise cause and mechanisms of environmentally induced renal injury remains a challenge for which various scientific disciplines need to be involved. Investigations in this field are confronted with the apparent infinite types of toxins, their mutual interaction, handling/metabolization by the body, ways of exposure, etc. Although interdisciplinary efforts and persistence are required to identify, mechanistically unravel and tackle environmental toxin-induced pathologies, research eventually pays off in ameliorated working/living conditions and development of preventive/therapeutic strategies. This review was compiled to particularly emphasize the need for a maintained awareness of environmental threats in general and those targeting the kidney. Different mechanisms of renal toxicity are illustrated and discussed, thereby focusing on three types of environmental toxins, namely aristolochic acid, melamine and heavy metals.

Biomarkers in Veterinary Medicine

This article summarizes the relevant definitions related to biomarkers; reviews the general processes related to biomarker discovery and ultimate acceptance and use; and finally summarizes and reviews, to the extent possible, examples of the types of biomarkers used in animal species within veterinary clinical practice and human and veterinary drug development. We highlight opportunities for collaboration and coordination of research within the veterinary community and leveraging of resources from human medicine to support biomarker discovery and validation efforts for veterinary medicine.

Cytotoxicity, organ distribution and morphological effects of melamine and cyanuric acid in rats

Melamine (Mel) is used widely as a basic organic chemical intermediate in several products. Within the last 10 years there have been two high-profile Mel exposures that caused toxicological concern, especially regarding food adulteration.

OBJECTIVE

This study aimed to determine the toxicity of Mel and one of its homologs, cyanuric acid (Cya), in vitro and in vivo.

MATERIALS AND METHODS

The IC₅₀ of Mel and Cya was determined by the MTT assay in NRK-52E and 293T cell lines. Organ-specific toxicity was assessed using the following dosing paradigm of Wistar rats: group 1: normal saline; group 2: Mel (180 mg/kg); group 3: Cya (150 mg/kg); and group 4: Mel (180 mg/kg) + Cya (150 mg/kg).

RESULTS

The NRK cell toxicity studies on Mel and Cya revealed IC₅₀ values of 1.89 mg/mL and 4.20 mg/mL, respectively. Similarly, Mel and Cya IC₅₀ values in 293T cells were 2.07 mg/mL and 3.71 mg/mL, respectively. Histopathologic studies revealed crystals in the renal medulla-cortex and loss of chief cells in the lining of the stomach in the group receiving Mel plus Cya. HPLC-MS analysis of organ homogenates showed that the concentration of Mel was greatest in the animals receiving a combination of both Mel and Cya.

DISCUSSION AND CONCLUSION

Mel is more toxic than its homolog Cya. The kidney is the most affected organ. Mel was present at high concentration not only in the kidneys, but also in the uterus and liver, informing the scope of future studies on the mechanism of Mel and Cya toxicity.