Effects of low‐dose melamine exposure during pregnancy on maternal and fetal kidneys in rats

Despite the previous reports on melamine contamination in high concentrations some years ago, there were not many studies on low‐level exposure in daily life, particularly in pregnancy. We investigated the effect of low‐dose melamine on the kidneys of the pregnant rats and their developing embryos/fetuses during various gestational stages namely implantation, gastrulation, organogenesis, maturation and whole pregnancy. Our results showed that the repeated low level of melamine (12.5, 25, and 50 mg/kg bw/d) during pregnancy did not cause obstruction of renal tubules although more precipitating crystals were found in the early gestational periods. Simple hyperplasia in the maternal tubules and pelvic epithelium were more prominent after exposed to melamine during the whole gestational period. Neonatal kidneys significantly suffered more from congestion in glomeruli and interstitium, dilated tubules and interstitial edema after melamine administration to the mother in the late and the whole gestational periods. A trend of advance of glomerular development in fetuses was also observed. We conclude that in utero exposure of low‐level melamine could post a risk on the kidneys of the pregnant mother as well as the developing fetuses, which may further increase the possibility of other health problems later in life.     

Development of ELISA for melamine detection in milk powder

A sensitive ELISA method was developed based on a monoclonal antibody to detect melamine in milk powder. Two haptens were prepared using the melamine structural analogue, 2-chloro-4, 6-diamino-1, 3, 5-triazine. The obtained antibody belonged to the IgG1κ family and had high affinity for melamine (affinity constant was 3.09×10⁹). The antibody could also recognise cyromazine (cross-reactivity was 131%) and had low cross-reactivity toward the haptens. The effects of pH, ionic strength and organic solvents on ELISA performance were evaluated. The lowest IC₅₀ value (6.0±0.55 ng/mL) and the limit of detection in milk powder, 50 ng/g, were achieved under optimised conditions. Milk powder spiked at two levels of melamine (100 ng/g and 500 ng/g) was analysed with this ELISA method. Good recovery was obtained (76.2±7.3% at the 100 ng/g spiked level and 91.4±5.0% at 500 ng/g).     

Evaluation of Hybrid Melamine and Steel Fiber Reinforced Geopolymers Composites

This study investigated the influence of the steel and melamine fibers hybridization on the flexural and compressive strength of a fly ash-based geopolymer. The applied reinforcement reduced the geopolymer brittleness. Currently, there are several types of polymer fibers available on the market. However, the authors did not come across information on the use of melamine fibers in geopolymer composites. Two systems of reinforcement for the composites were investigated in this work. Reinforcement with a single type of fiber and a hybrid system, i.e., two types of fibers. Both systems strengthened the base material. The research results showed the addition of melamine fibers as well as steel fibers increased the compressive and flexural strength in comparison to the plain matrix. In the case of a hybrid system, the achieved results showed a synergistic effect of the introduced fibers, which provided better strength results in relation to composites reinforced with a single type of fiber in the same amount by weight.     

三聚氰胺-三聚氰酸网状结构诱导三聚氰胺尿路结石的成核作用

目的：探讨一种三聚氰胺尿路结石的发生机制模型。方法：收集三聚氰胺尿路结石24枚（试验组）,随机选择19枚成人尿路结石作为对照组,测定试验组患儿肾功能和血尿酸、肌酸水平。使用高效液相色谱法测定结石样本肌酐、肌酸和尿酸含量,使用高分辨透射电镜研究上述结石提取物、人工制备的三聚氰胺-三聚氰酸聚合物、色谱级尿酸、肌酸和肌酐标准品结构。结果：试验组患儿血生化指标均正常,且无个体间显著差异。试验组结石肌酸（6．17±8．09μg／gvs0．19±0．16μg／g,P=0．000）和肌酐（20．49±21．91／zg／gVS2．09士1．06μg／g,P=0．008）含量较对照组显著增高。但患儿血生化指标与上述结石指标之间无明显相关（P〉0．05）。电镜研究显示：试验组结石核心区域提取物中发现的网状结构与人工制备的三聚氰胺-三聚氰酸聚合物结构极其相似,而且肌酸、肌酐和尿酸分子均小于上述网状结构网格尺寸。结论：本研究首次证实三聚氰胺结石中存在独特的类三聚氰胺-三聚氰酸聚合物的网状结构,其可能参与结石发生中的成核作用。     

Fly-Ash-Based Geopolymers Reinforced by Melamine Fibers

This paper presents the results of research on geopolymer composites based on fly ash with the addition of melamine fibers in amounts of 0.5%, 1% and 2% by weight and, for comparison, without the addition of fibers. The melamine fibers used in the tests retain their melamine resin properties by 100% and are characterized by excellent acoustic and thermal insulation as well as excellent filtration. In addition, these fibers are nonflammable, resistant to chemicals, resistant to UV radiation, characterized by high temperature resistance and, most importantly, do not show thermal-related shrinking, melting and dripping. This paper presents the results of density measurements, compressive and flexural strength as well as the results of the measurement of thermal radiation changes in samples subjected to a temperature of 600 °C. The results indicate that melamine fibers can be used as geopolymer reinforcement. The best result was achieved for 0.5% by weight amount of reinforcement, approximately 53 MPa, compared to 41 MPa for a pure matrix. In the case of flexural strength, the best results were obtained for the samples made of unreinforced geopolymer and samples with the addition of 0.5% by weight of melamine fibers, which were characterized by bending strength values above 9 MPa, amounting to 10.7 MPa and 9.3 MPa, respectively. The thermal radiation measurements and fire-jet test did not confirm the increasing thermal and fire resistance of the composites reinforced by melamine fiber.     

Risk factors for acute kidney injury (AKI) in infants with melamine-associated urolithiasis and follow-up: a multi-center retrospective analysis

An epidemic of urinary tract stones was noted among infants in China, 2008. This event was believed to be associated with consumption melamine-contaminated powdered formula. The patients with symptoms and clinical manifests had already been analyzed in our previous studies. In this study, our aim is to investigate the risk factors of melamine-associated acute kidney injury (AKI) and the potential relationship toward children growth in our five years follow-up. A total of 619 infants with melamine-associated urolithiasis were admitted into 20 different hospitals in the Gansu province, China. All clinical data were divided into AKI and control groups according to the occurrence of AKI. Univariate and multivariate analyses were performed with a logistic regression model to assess the independent risk factors of AKI. Logistic regression analysis revealed that the odds ratio (OR) of AKI was 19.62 in the group of infants who consumed Sanlu® milk powdered infant milk formula. A higher prevalence of AKI was observed in infants age of 6–11 months (OR: 9.59, p?p?p?melamine infant formula (Sanlu® milk powdered infant formula), age (6–17 months) and symptoms of URTI, diarrhea, dehydration or fever were risk factors of AKI in infants with melamine-associated urolithiasis.     

Identification of melamine/cyanuric acid‐containing nephrolithiasis by infrared spectroscopy

Melamine‐contaminated milk formula caused infant nephrolithiasis in some areas of China. Its combination with cyanuric acid causes crystallization in renal tubules. Following this renal damage and even renal failure that require long‐term hemodialysis has been reported. Therefore, correct and timely diagnosis of these complex diseases is critical. Melamine containing stone is a combination of equal molar ratios of common stone compositions that has been reported from previous animal studies. We have previously identified the compositions of urinary tract stones with infrared (IR) spectroscopy. We hypothesized that the absorbance of wavelength of IR can identify melamine/cyanuric acid in the presence of mixing human stone compositions. In this study, we made an artificial stone composition and examine under IR absorbance by mixing equal molar ratios of melamine/cyanuric acid with different types of human urinary stones, and established a reference of IR analysis for the identification of melamine/cyanuric acid‐containing human urinary tract stones. Knowledge of the precise stone composition allowed institution of appropriate prophylactic dietary and medical therapy and this may help in the prevention of urinary stone recurrence. The results are promising that melamine and cyanuric acid can be identified clearly in a low percentile (～1%) of stone mixture pellet. Therefore, IR seems to be an ideal tool for the identification of melamine/cyanuric acid‐containing stones. J. Clin. Lab. Anal. 24:92–99, 2010. © 2010 Wiley‐Liss, Inc.     

The characteristics of immune system changes in children who ingested melamine-contaminated powdered formula in China

Since 2008, the food safety issue of melamine poisoning has again become a health scare for children. The mechanism of how melamine initiates kidney stones and kidney-associated renal complications is still unknown. Some children who ingested melamine-contaminated powdered formula had leukocyturia, but none had typical symptoms of urinary tract infection. We believed that the children's immune systems might have some changes. We followed up 170 children who ingested melamine-contaminated powdered formula and tested their blood and urine and to observe their immune state, and also performed ultrasonography. In the immune responses of children with stones, immunoglobulin M takes a major immune response and the level of CD3⁺, CD4⁺ decreased compared with children without stones. There was no difference in complete blood count between the children with stones and those without stones. We concluded that leukocyturia had a certain relationship with non-urinary tract infectious renal disease and these children are susceptible to infectious diseases.     

Effects of bile acids on the mutagenicity and recombinogenicity of triethylene melamine in yeast strains MP1 and D61.M

When Saccharomyces cerevisia MP1 was treated with bile acids alone or in combination with triethylene melamine (TEM), cholic acid was found to be comutagenic and antirecombinogenic while lithocholic acid had the opposite effect. Other bile acids enhanced the mutagenic and recombinogenic effects of TEM. Chenodeoxycholic acid, deoxycholic acid and ursodeoxycholic acid had stronger comutagenic than corecombinogenic effects; hyodeoxycholic acid did not show this difference.Ox gall and a mixture of bile acids antagonized the genotoxic effect of TEM, and it therefore seems plausible that in normal composition bile acids neutralize each other, i.e., the comutagenic (corecombinogenic) effect of one substance is antagonized by the antimutagenic (antirecombinogenic) effect of another one. However, when the composition is altered, bile acids may become harmful.Experiments with yeast strain D61.M were performed in order to test for aneuploidy caused by bile acids; no effects were observed.Dedicated to Professor Dr. med. Herbert Remmer on the occasion of his 65th birthday