OBJECTIVEWe tested whether melamine nephrotoxicity was exacerbated by urate (a typical component of renal stones in humans) in rats with hyperuricemiainduced by the uricase inhibitor, potassium oxonate (Oxo).

METHODSRats were exposed to melamine or Oxo alone or combinations of melamine (200-400 mg/kg) and Oxo (200-600 mg/kg) for 3 consecutive days. Kidney injury was evaluated by renal biochemical functions, histomorphology, and lipid peroxidation. Kidney crystals were analyzed for their composition.

RESULTSNephrotoxicity was minimal in animals administered melamine or Oxo alone, but it was demonstrable in animals administered at least 800 mg/kg of the two compounds combined. All rats in the 400+600 (melamine+Oxo) and 400+400 mg/kg groups and 4 out of 6 in the 200+600 mg/kg group died within 3 days; no rat died in the 200+400 or 200+200 mg/kg group. Dose-dependent renal damage resembling clinical findings in affected patients was observed in rats administered the two compounds. Crystal composition determination revealed the existence of melamine and uric acid in the affected kidneys, resembling human stones.

CONCLUSIONOur findings suggest that uric acid plays a key role in melamine-related kidney injury in humans. Future studies should consider uric acid together with melamine when examining adverse effects in humans.

Animals ; Disease Models, Animal ; Hyperuricemia ; chemically induced ; complications ; Kidney Diseases ; chemically induced ; Lipid Peroxidation ; drug effects ; Male ; Oxonic Acid ; Rats, Wistar ; Triazines ; toxicity

In recent years there have been more widely and deeply studies in investigating melamine toxicity. Generally, it is believed that the main target of melamine is the urinary system. However, previous studies revealed that it also had additional biological actions. Obviously, the toxicity mechanisms of melamine have not been fully clarified. It is well known that fetus and infant periods play the most fundamental role in the brain development. And melamine can pass through the placental and blood-brain barrier, and then exerts toxic effects on the central nervous system. This article reviewed the reports about the topic in recent years, for better understanding the dangers of melamine to infants and providing experimental data for further study.
Animals ; Blood-Brain Barrier ; drug effects ; Brain ; growth & development ; Central Nervous System ; drug effects ; Cognition ; drug effects ; Female ; Humans ; Maternal-Fetal Exchange ; drug effects ; Pregnancy ; Triazines ; pharmacokinetics ; toxicity

Animals ; Male ; Organ Size ; Rats ; Rats, Sprague-Dawley ; Spermatozoa ; drug effects ; growth & development ; Testis ; drug effects ; Triazines ; toxicity

OBJECTIVETo determine the prevalence of urolithiasis in young children fed infant formula (IF) contaminated with melamine, and the association between IF consumption and urolithiasis.

DESIGNA total of 2 733 children < or = 3 years of age on September 1, 2008 in two townships of Gansu Province, China were studied. Cases of urolithiasis were diagnosed by ultrasonography. Milk product consumption was determined by their caregivers. Remaining IF samples were tested for melamine and cyanuric acid.

RESULTSOf 2 733 eligible children in the two townships, 2 186 (80%) were enrolled in our study. Overall, 16.6% (362) of 2 186 children had urolithiasis. The prevalence was 24.6% in children exclusively fed Sanlu brand IF, 9.7% in those fed other IF, and 8.5% in those fed exclusively on other milk products. For children exclusively breast-fed, no urolithiasis was found (P < 0.05). The prevalence of urolithiasis was 11.4% in children fed 400 g of Sanlu IF, rising to 37.5% in children fed over 25 600 g. Of 48 Sanlu IF samples, 91.7% contained melamine (median = 1 800 ppm; range = 45-4 700) and 66.7% contained cyanuric acid (median = 1.2 ppm; range = 0.4-6.3). Melamine was also detected in 22.2% of 36 other brand IF (median = 27.5 ppm, range = 4-50).

CONCLUSIONSUrolithiasis was associated with melamine-contaminated IF. Although one product caused most morbidity, other milk products may have also contributed to the outbreak.

Child, Preschool ; Data Collection ; Food Contamination ; Humans ; Infant Food ; analysis ; Triazines ; toxicity ; Urolithiasis ; chemically induced

This study assessed the toxicity of melamine against the unicellular eukaryotic system of Tetrahymena (T.) pyriformis exposed to 0, 0.05, 0.25, 0.5, 2.5, and 5 mg/mL of melamine. Cell growth curves of different cultures, the half maximum inhibition concentration (IC50) value of melamine, and morphological changes in cells were obtained via optical and transmission electron microscopic observation. The effects of eleven melamine concentrations, 0.25, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 and 5 mg/mL, on protein expression levels of T. pyriformis were examined using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The results showed an obvious inhibitory effect of melamine on the growth of eukaryotic cells. Cell growth dynamics indicated that the IC50 value of melamine on T. pyriformis was 0.82 mg/mL. The cellular morphology was also affected in a concentration-dependent manner, with characteristics of atrophy or cell damage developing in the presence of melamine. The relative contents of the top four main proteins corresponding to peak mass-to-charge ratios (m/z) of 4466, m/z 6455, m/z 6514, and m/z 7772 in the MALDI-TOF-MS spectra were all found to be closely correlated with the melamine concentrations. In conclusion, exposure of eukaryotic cells to melamine could inhibit cell growth, cause changes in cytomorphology and even disturb the expression of proteins in a concentration-dependent manner. The described method of examining four sensitive proteins affected by melamine was also proposed to be used in a preliminary study to identify protein biomarkers in T. pyriformis.
Animal Feed/analysis/toxicity ; Biological Markers/analysis ; Food Additives/analysis/toxicity ; Inhibitory Concentration 50 ; Microscopy, Electron, Transmission ; Protozoan Proteins/analysis ; Spectrometry, Mass, Matrix-Assisted Laser De ; Tetrahymena pyriformis/cytology/*drug effects ; Triazines/*toxicity

Female ; Food Contamination ; Humans ; Infant ; Infant Formula ; Kidney Calculi ; chemically induced ; diagnosis ; Male ; Triazines ; toxicity

OBJECTIVEto investigate pathological changes and mRNA expression of apoptosis genes bcl-2, bax and Caspase-3 in rat kidney tissue after rats are administrated with melamine for 28 days.

METHODS10 male SD rats and 10 female SD rats in each group were administrated with three doses of melamine (low dose, middle dose, high dose) by gavage for 28 days. The animals were divided into three experimental groups and one control group. The doses for male rats were 200, 400, 800 mg/kg, but for female rats they were 150, 300, 600 mg/kg. After melamine treatment the animals were sacrificed and the kidneys were taken out for pathological analysis and for detecting mRNA expression of bcl-2, bax and Caspase-3 with fluorescent quantitative PCR assay.

RESULTSthe tubular cylinders were observed in three experimental groups. The positive rates of tubular cylinders in three groups (from low dose to high dose) were 11/20, 13/20, 16/20, respectively. Additionally, melamine induced a significant decrease in mRNA expression of bcl-2 at low dose, middle dose or high dose, bcl-2 expression decreased by 20.58% - 49.51% in three groups treated with melamine. Furthermore, bax mRNA levels increased by 44.66% - 300.96% in groups treated with three doses of melamine, and Caspase-3 mRNA levels increased by 64.76% - 360.75% in groups treated with three doses of melamine.

CONCLUSIONSmelamine could induce pathological changes of rat kidneys, and it also induces a significant alteration of apoptosis Bcl-2, Bax and Caspase-3 mRNA expression in rat kidney tissue.

Animals ; Apoptosis ; Caspase 3 ; genetics ; metabolism ; Female ; Kidney ; drug effects ; metabolism ; pathology ; Kidney Tubules ; drug effects ; metabolism ; pathology ; Male ; Proto-Oncogene Proteins c-bcl-2 ; genetics ; metabolism ; RNA, Messenger ; genetics ; Rats ; Rats, Sprague-Dawley ; Triazines ; toxicity ; bcl-2-Associated X Protein ; genetics ; metabolism

BACKGROUNDIn 2008, a sharp increase of the number of children diagnosed with urinary calculi was observed in China, 9433 children were diagnosed as having melamine-induced urinary calculi at outpatient clinic in Beijing Children's Hospital. This study examined the therapeutic efficacy of potassium sodium hydrogen citrate (PSHC) used to treat melamine-induced urinary stones in Chinese children who consumed melamine-containing infant formula.

METHODSSeventy-two infants and children (average age (18.2 +/- 7.7) months) who were diagnosed with urinary calculi were randomly divided into three treatment groups using the SAS Plan program. Group 1 was given a low dose (1 g/d) of PSHC, group 2 was given high dose of PSHC (2 g/d) and group 3 was given no PSHC (control group). The dose of drug was adjusted according to the baseline urinary pH. This study analyzed the influence of the dose of PSHC, the age of patients, stone size and position, and urinary pH on the level of efficacy of PSHC (cured, effectively treated or not cured).

RESULTSAfter 1 - 6 months of therapy, 19 patients from group 1, five patients from group 2 and six patients from group 3 were cured. Five patients from group 1, five patients from group 2 and four patients from group 3 were effectively treated. There were significant differences in therapeutic efficacy between the two treatment doses after 3 and 6 months as measured by the increase in the successful expulsion rate and time of melamine-induced urinary calculi. After 6 months the mean time of expulsion of urinary calculi in groups 1 and 2 was significantly shorter than in the control group.

CONCLUSIONSPSHC can significantly increase the successful expulsion rate and time of melamine-induced urinary calculi. The therapeutic efficacy is affected by PSHC dose, treatment duration, calculi position, and urinary pH. There is no relationship between the therapeutic efficacy and the stone size or patient age.

Adolescent ; Adult ; Child ; Child, Preschool ; China ; Citrates ; therapeutic use ; Female ; Humans ; Hydrogen-Ion Concentration ; Infant ; Infant, Newborn ; Male ; Middle Aged ; Treatment Outcome ; Triazines ; toxicity ; Urinary Calculi ; chemically induced ; drug therapy ; urine ; Urine ; chemistry ; Young Adult

Melamine (Tripolycyanamide) and its derivatives have recently become a public concern on food safety. To better understand melamine and its major derivative cyanuric acid.literature on their chemical properties, metabolism, biological effects, relevant toxicology studies, and the detection methods is reviewed. Studies indicate that the acute toxicity of melamine and cyanuric acid is low. In mammalian, these compounds are hardly metabolized in vivo and are rapidly eliminated in the urine. When used in large dosage,these compounds demonstrate marked renal toxicity,as well as toxic effect towards heart. The renal toxicity is exemplified by the calculi formation, acute renal failure, and subsequently induced carcinomas of the urinary bladder. Among the tested species, male cats and rats are more prone to be affected by the compounds. The HPLC/MS/MS is becoming the mainstay of the detection methods. Despite of the achieved knowledge on melamine and cyanuric acid, further research is warranted to unveil the mechanism of underlying susceptibility of kidney, to develop better analytic methods,and to explore possible biomarkers for better clinical diagnosis.
Animals ; Carcinogens ; toxicity ; Cats ; Female ; Kidney Diseases ; chemically induced ; Male ; Rats ; Species Specificity ; Triazines ; toxicity ; Ureteral Calculi ; chemically induced

Food Contamination ; Humans ; Infant ; Triazines ; toxicity ; Urinary Calculi ; diagnosis ; etiology ; therapy