Evaluation of the cytotoxic and genotoxic effects by melamine and cyanuric acid co-exposure in human embryonic kidney 293 cells

The melamine and cyanuric acid (CA) complex has been suggested to cause the toxic effects observed in melamine-contaminated food or milk. However, the cytotoxic and genotoxic effects of co-exposure to melamine and CA are not fully clear. Therefore, the cytotoxic effects of melamine and CA were first examined by co‐exposure in human kidney 293 cells using the MTT assay. During a 24-h period for the three concentrations tested (0.5, 1, and 5 mg/mL), neither melamine nor CA alone showed significant toxic effects on 293 cells at 0.5 mg/mL, while higher concentrations led to decreased in cell viability. However, co-exposure to several combinations of melamine and CA [100:1, 10:1, 1:10, and 1:100 (v:v), at a final concentration of 0.5 mg/mL] did cause cytotoxicity with higher levels of CA leading to higher cytotoxicity. By contrast, while neither melamine nor CA alone induced phosphorylated-H2AX (γH2AX) foci formation, melamine and CA at a 100:1 ratio induced γH2AX foci 24 h post-treatment. The alkaline comet assay also revealed the presence of DNA damage following melamine and CA co-exposure. In vivo assay also revealed the presence of melamine-CA complex in the kidney. These data indicated that the cytotoxic and genotoxic effects of melamine and CA co-exposure differ from those of melamine or CA alone.

Preparation of Melamine Molecularly Imprinted Surface Plasmon Resonance Sensor and Its Analytical Application / 分析化学

The melamine molecular imprinted polymer ( MIP ) membrane immobiliZed on the surface of the surface plasmon resonance ( SPR) chip was prepared with allylcyanurate and ethylene glycol dimethacrylate as a functional monomer and cross-linker, respectively.Based on the ratio of the intercept to the slope of Langmuir equation for imprinted polymer, the association constant ( Kass ) of imprinted sites in the imprinted film to melamine was calculated to be 1.40 × 108 L/mol.The SPR sensor showed high selectivity to the template molecule melamine, and the best response was obtained at pH=7.5.The method showed good linearity in the melamine concentration range of 0.1-10.0 nmol/L ( R=0.9991 ).Based on a signal to noise ratio of 3, the detection limits of melamine were 62.6 pmol/L and 56.4 pmol/L for the milk and milk powder, respectively.The recoveries were 91.5% for milk and 92.0% for milk powder.These results suggest that SPR sensing combined with MIP film is a promising alternative method for detection of melamine.

Infant Formula Crisis in China: A Cohort Study in Sichuan Province.

China has become the largest market of infant formula in the world. The consumption of infant formula is widespread across the country. This study investigated the opinions of Chinese mothers on infant formula. A prospective cohort study (n=695) was undertaken in 2011 in Sichuan province of China two years after the melamine scandal. Infant-feeding practices and mothers’ opinions on infant formula-use were documented in detail. A total of 674 mothers (97%) had initiated breastfeeding by discharge. Of the 21 mothers who did not commence breastfeeding, 13 made a decision to exclusively feed their babies with infant formula because of hepatitis B virus infection. Nearly 70% of newborns received infant formula as their first feed, and the prevalence increased to 88% within one month. Having insufficient breastmilk was perceived by the majority (77%) of mothers as the reason behind infant formula feeding. About half (46%) of the mothers agreed with or were ambivalent that infant formula feeding does not reduce their breastmilk production. More than one-third (38%) of women thought that formulafed infants sleep longer at night than those who are breastfed. In addition, this perception was positively associated with the use of formula within one month postpartum (p=0.003). In conclusion, mothers’ opinions appear to influence the use of infant formula in China. There is a need for further education on breastfeeding and infant-feeding options to maintain and improve breastfeeding outcomes in China.

Melamine Nephrotoxicity is Mediated by Hyperuricemia / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>We 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).</p><p><b>METHODS</b>Rats 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.</p><p><b>RESULTS</b>Nephrotoxicity 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.</p><p><b>CONCLUSION</b>Our 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.</p>

A Label-free and Separation-free Detection for Melamine Based on Surface Enhanced Raman Scattering / 分析化学

A rapid, sensitive, label-free and separation-free analytical method for determination of melamine ( MA) was developed based on surface enhanced Raman scattering ( SERS ) effect of gold nanoparticles. Through tri-sodium citrate reduction method, gold nanoparticles with average diameter of 30 nm were obtained. The melamine detection platform was constructed after self-assembling 4-mercapto phenylboronic acid (4-MPBA) on the surface of gold nanoparticles through Au S covalent bond. When MA existed in solution, 4-MPBA functionalized gold nanoparticles would aggregate because of strong hydrogen bond interaction between MA and 4-MPBA. Moreover, following increase of the concentration of MA, gold nanoparticles would aggregate more intensively and form more hot spots. As a result, Raman signal of 4-MPBA and MA was enhanced greatly. The characteristic Raman peaks of 4-MPBA and MA respectively located at 1076 cm-1 and 715 cm-1 . Hence, the qualitative and quantitative detection for MA were realized based on the ratio value of I715 cm-1 to I1076 cm-1 . The linear range of MA detection was 0 . 1 μmol/L-1. 5 μmol/L. The limit of detection (LOD) reached 0. 02 μmol/L in terms of three times signal to noise.

To evaluate the clinical curative effect of meglumine adenosine cyclophosphate combined with perindopril on patients with chronic congestive heart failure / 中华急诊医学杂志

Objective To explore the relationship of plasma NT-proBNP level and severity of chronic congestive heart failure (CHF) and investigate the curative effect and security of meglumine adenosine cyclophosphate (MAC) combined with perindopril on patients with CHF.Methods From June 2011 to June 2013,126 inpatients with chronic congestive heart failure were randomly divided into A group (42 cases,routine therapy),B group (41 cases,routine therapy and perindopril) and C group (43 cases,routine therapy and perindopril plus MAC),all cases treated for 14 days.The left ventricular ejection fraction (LVEF) and left ventricular end-diastolic diameter (LVEDD) by echocardiography and plasma NT-proBNP levels were evaluated before and after 14 days therapy.Results The plasma NT-proBNP levels in NYHA Ⅱ ～ Ⅳ classes were significantly difference compared each other between any two classes (P ＜0.05) and the levels was positively correlated with NYHA cardiac function class and LVEDD (r =0.617,P ＜ 0.01 ; r =0.412,P ＜ 0.01),negatively correlated with LVEF (r =-0.372,P ＜ 0.01).After 14 days therapy,compared with A group,the LVEF and LVEDD significantly improved (P ＜ 0.05) and NT-proBNP level significantly decreased (P ＜ 0.05) in B,C groups; Compared with B group,C group had lower NT-proBNP level (P ＜ 0.05) although no further improvement in cardiac function.Conclusions The plasma NT-proBNP level is correlated closely with the severity of CHF and it is a good examination of diagnose,therapy and evaluating prognosis of CHF.Perindopril may significantly decline plasma NT-proBNP level and improve cardiac function of CHF patients,combined with MAC may further decline plasma NT-proBNP level although not further improved LVEF.Giving MAC and perindopril to patients with CHF was secure and patients tolerated it well.

Simple and Rapid Detection of Melamine in Milk Based on T-Melamine-T Duplex Structure and SYBR Green Ⅰ / 分析化学

A novel fluorescence homogeneous biosensing strategy was developed for simple, rapid and sensitive detection of melamine in milk by using the polythymine oligonucleotide T24 and SYBR Green Ⅰ. In the absence of melamine, the fluorescence of SYBR Green Ⅰ was weak. The interactions between the single strand oligonucleotide T24 and SYBR Green Ⅰ were weak. In contrast, the presence of melamine drove the formation of T-melamine-T folded structure and enabled the SYBR Green Ⅰ to intercalate into double-strand DNA, resulting in the enhancement of fluorescence intensity. The results revealed that the method allowed a sensitive, simple, and rapid assay of melamine with a linear response range from 0. 1 μmol/L to 10 μmol/L and a detection limit of 35 nmol/L.

Synergistic effect of melamine in combination with cyanuric acid on urinary tract toxicity in rats / 동물의과학연구지

The present study investigated the urinary tract toxicity of melamine alone or in combination with cyanuric acid in rats. Male rats were orally administered melamine alone (800 mg/kg) or melamine plus cyanuric acid (50 mg/kg each) for 3 consecutive days. Although melamine treatment did not show any significant difference in body weight, kidney or urinary bladder weight, serum blood urea nitrogen (BUN) or creatinine levels, it caused a decrease in urinary pH and mild histopathological alterations in the kidney and urinary bladder. In contrast, co-administration of melamine and cyanuric acid induced a decrease in body weight, an increase in kidneys and urinary bladder weights, and an elevation in serum BUN and creatinine levels, which were not observed in animals treated with melamine alone. Histopathological examination showed that the incidence and severity of histopathological lesions in the kidney and urinary bladder were much higher than those in the melamine group. Urinalysis revealed an increase in urine occult blood, leukocytes and protein and a decrease in urinary pH. These results indicate that concomitant administration of cyanuric acid synergistically potentiated the urinary tract toxicity induced by melamine in rats. In this study, we first demonstrated the synergistic toxic effects of melamine in combination with cyanuric acid on urinary bladder and urinalysis in rats.

The mechanism of melamine-induced renal damage in rats / 中华泌尿外科杂志

Objective To investigate the mechanism of melamine-induced renal damage in rats.Methods 48 male SD rats were randomly divided into 4 groups with 12 in each group and feed for 3 months.Group A were the control group,feed with standard granule feedstuff and drinking tap water.Group B were stone-induced group,feed with granule feedstuff containing 3％ Mel and drinking tap water.Group C were feed with granule feedstuff containing 3％ Mel and drinking water containing 2％ taurine.Group D were feed with standard granule feedstuff and drinking water containing 2％ taurine.Every week 24 h urine was collected to test PH,SCr,uric acid,protein,8-IP,H2O2 and Mel level.All rats were sacrificed at the end of 3 months.Blood creatinine detection,renal pathology analysis ( HE and Oil ep-red O dyeing,immunohistochemical) and mitochondria separation and detection were undertaken. ResultsMel was not detedted in urine of Group A and Group D.The urine concentration of Mel in Group B and Group C in 1 week,2 weeks,3 weeks,4 weeks were 3.16 ±0.45,4.39 ±0.213,5.40 ±0.28,5.50 ±3.26 and 3.52 ±0.49,4.32 ± 0.135,5.34 ± 0.40,5.46 ± 2.99 mg/ml,respectively.Compared with Group A,the Mel concentration in urine of Group B and C were drug exposure time dependent.In Group A,the urine protein,urine creatinine clearance,serum creatinine,and renal/weight ratio were 6.45 ± 1.45 mg/24 h,28.0 ± 7.4mmol/l,0.56 ±0.03 ml · min-1 · 100g-1,2.29 ±0.89 mg/g,while in Group B and C,the urinary protein urine,serum creatinine,creatinine clearance,kidney/weight ratio were 14.56 ± 7.69,56.8 ± 5.2,0.29 ±0.05,4.16 ±0.27 and 16.44 ±6.29,55.8 ±7.4,0.30 ±0.07,4.40 ±0.56,respectively.Compared with group A,in Group B and C,the urinary protein increased significantly,urine creatinine clearance reduced,serum creatinine reduced,and renal/weight ratio increased.Compared with Group B,the improvement of renal function in Group C was not significant,and the decrease of serum creatinine and urinary protein were not obvious (P ＞ 0.05).In Group B and C,the urine H2O2,8-IP and mitochondrial oxidatie detection reagent SOD,GSH-PX numerical were 28.5 ± 5.2 mmol/1,3.26 ± 1.6 pg/ml,21.1 ± 7.8 U/mg prot,19.0 ±2.5 energy unit and 26.7 ±4.8 mmol/l,2.99 ±8.5 pg/ml,20.3 ±6.9 U/mg prot,17.9 ±4.8 energy unit,respectively.The difference between Group B and C was not statistically significant (P ＞0.05).Pathological analysis showed Mel was mainly concentrated in crystal tubular lumen (Group B and C),kidney interstitial damage was apparent,and kidney inflammation and fibrosis progressive developed with the increase of the drug exposure time. Conclusions Mel can induce kidney damage and stone formation in rats,and stone was mainly in tubular location in inner medullary zone.It is not the oxidative stress way that Mel leads to kidney damage.

Chemiluminescence determination of melamine with Luminol-K3Fe（CN）6 system / 药物分析学报

A sensitive chemiluminescence（CL） method was developed for determining melamine in urine and plasma samples based on the fact that melamine can remarkably enhance the chemiluminescence of Luminol-K3 Fe（CN）6 system in alkaline medium. The determination conditions were optimized. Under optimum conditions, the chemiluminescence intensity had a good linear relationship with melamine in the range of 9.0 × 10

In vitro toxicity of melamine against Tetrahymena pyriformis cells

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.

Increased Nephrotoxicity after Combined Administration of Melamine and Cyanuric Acid in Rats / 한국실험동물학회지

Renal toxicity by melamine in combination with cyanuric acid (1:1) was investigated. Male rats were orally administered melamine plus cyanuric acid (5, 50 or 400 mg/kg each) for 3 days. In contrast to a negligible effect by melamine alone (50 mg/kg, a no-observed-adverse-effect-level: NOAEL), co-administration with cyanuric acid markedly increased the concentrations of blood urea nitrogen and creatinine, as well as kidney weight. A high dose (400 mg/kg) of melamine plus cyanuric acid induced more severe kidney toxicity. The increased blood parameters for kidney toxicity and organ weight lasted longer than 4 days. Combined treatment with melamine and cyanuric acid (50-400 mg/kg each) resulted in many gold-brown crystals and toxic lesions in renal tubules, which were not observed in animals treated with melamine alone (50 mg/kg). These results indicate that only a 3-day exposure to melamine in combination with cyanuric acid causes severe renal damage, even at a NOAEL for melamine found in a 13-week toxicity study. Therefore, it is suggested that the tolerable daily intake or regulatory/management levels of melamine need to be re-considered for cases of co-exposure with cyanuric acid.

Chemiluminescence determination of melamine with LuminoI-K3Fe(CN)6 system / 药物分析学报

A sensitive chemiluminescence(CL) method was developed for determining melamine in urine and plasma samples based on the fact that melamine can remarkably enhance the chemiluminescence of Luminol-K3 Fe(CN)6 system in alkaline medium.The determination conditions were optimized.Under optimum conditions,the chemiluminescence intensity had a good linear relationship with melamine in the range of 9.0 × 10 97.0 × 10 6 g/mL with a correlation coefficient of 0.9992.The detection limits (3σ) were 3.54 ng/mL for urine sample and 6.58 ng/mL for plasma sample.The average recoveries of melamine were 102.6％ for urine sample and 95.1％ for plasma sample.Melamine in samples was extracted with liquid-liquid extraction procedures and the assay results coincided very well with that determined with flow injection chemiluminescence method.The method provides a reproducible and stable approach for sensitive detection and quantification of melamine in urine and plasma samples.

One year follow-up study of urolithiasis in infants exposed to melamine-tainted powdered formula / 中华泌尿外科杂志

ObjectiveTo investigate the condition of infants with urolithiasis caused by melaminetainted powdered formula at one-year follow-up. Methods Eighty-one young children with melamine-induced urolithiasis were followed up,which included urinalysis,renal-function tests,urinary tests for biochemical markers of renal glomerular and tubular function,and ultrasonography.Eighty-one age-matched healthy infants without exposure to melamine-contaminated formulas were enrolled as controls. Results Fifty-one of the patients were male and 30 female,with a mean age of 26 months (range 13 -48 months).The 81 children were divided into 2 groups according to treatment protocols.Group 1 received conservative treatment ( n =54 ) and Group 2 received surgical treatment ( n =27 ).In Group 1,3 patients (5.6％) had stone-residual:1 girl had calculus of 0.4 cm in diameter in the left kidney and 2 girls had calculus of 0.3 cm in diameter in the right kidney.In Group 2,2 patients (7.4％) had stone-residual,1 boy had crystallization of 0.2 cm in diameter in the right kidney and 1 boy had calculus of 1.5 cm in diameter in the left kidney,positive stone was confirmed by X-ray and accepted percutaneous nephrolithotomy.Urinary microalbumin levels were significantly increased in the children with melamine-induced urolithiasis compared with the control group (P ＜0.01 ).Blood urea nitrogen and serum creatinine were within the normal range with no significant difference between the 2 groups. ConclusionsAt one-year follow-up most of the children exposed to melamine-tainted infant formula in both treatment groups had returned to a healthy state,suggesting a satisfactory outcome for both treatment options.However,surgery is recommended in patients with stoneresidual ＞ 10 mm.

Predictive value of spiral CT in composition changes of pediatric urinary stones / 中华泌尿外科杂志

Objective To investigate the predictive value of spiral CT in composition changes of pediatric urinary.Methods A total of 25 pediatric patients with urinary stones were investigated.Eighteen patients with renal stones were stratified into two groups:an alkalization therapy alone group ( n =9 ) and a comprehensive therapy group (n =9).Flame atomic absorption spectrum (AAS) was employed to measure calcium level of the pediatric urinary stones.Spiral CT was employed to measure the peak CT number in vitro of all the pediatric urinary stones and 61 adult urinary stones,which served as controls.Results All pediatric urinary stones contained calcium ( 0.11％ - 26.30％ ).A positive correlation was observed between the CT number of pediatric urinary stone and its stone calcium level ( r =0.855,P ＜ 0.01 ).Compared to the alkalization therapy alone group,the CT number and stone calcium level of pediatricrenal stones in the comprehensive therapy group were significant higher (stone CT number:162 ± 60 HU VS.783 ±476 HU,P ＜ 0.01 ; stone calcium level:1.30 ± 1.52％ VS 19.83 ± 7.48％,P ＜ 0.01 ).Compared to ≤400 HU pediatric renal stones,＞ 400 HU renal stones contained more calcium (21.71 ± 5.27％,1.65 ±1.82％,P ＜ 0.01 ) and failed to dissolve by alkalization therapy alone ( x2 =11.455,P ＜ 0.01 ).Conclusions CT could be a predictive tool for composition changes of pediatric urinary stones.In clinical CT scanning setting,＞400 HU pediatric urinary stones probably will contain more calcium and not be suitable for alkalization therapy alone.

Utility of CT Scan in Detection of Melamine - Associated Urinary Stones.

Objective To detail the utility of CT scan in detection of urinary stones induced by melamine tainted formula. Material and Methods A total of 1062 children fed with melamine-contaminated infant formula were screened for urinary stones in our institute from September through December 2008. Ultrasonography of the urinary tract system was performed in all these children. If the children with suspected stones or severe obstruction were presented after ultrasound examination, themulti-detector row CTurographic examination was advocated subsequently. Results Ultrasound examination in combination with multidetector row CT urography could increase the diagnostic rate from 3.4% (36/1062) by ultrasound examination alone to 4.6% (49/1062). Conclusions The specificity and sensitivity of the multidetector row CT urographic examination is higher than ultrasonography.

Breastfeeding Practice in Zhejiang Province, PR China, in the Context of Melamine-contaminated Formula Milk.

A prospective cohort study of 1,520 mothers from Zhejiang province of China was undertaken to determine the duration of breastfeeding and associated factors during the first six months postpartum. Most (95.3%) mothers had introduced complementary foods by six months, making them at risk from contaminated infant formula. The mean duration of ‘any breastfeeding’ was greater than 180 days but only 48 days for ‘exclusive breastfeeding’. Factors relating to cessation of any breastfeeding were maternal age, timing of the breastfeeding decision, admission of the infant to a special-care nursery, return of the mother to work, the early introduction of water and/or other complementary foods, and their location of residence. The introduction of infant formula before three months was positively associated with the late decision to breastfeed, births in city, and infants being given a prelacteal feed. To combat the melamine disaster, strategies to improve the duration of breastfeeding must be developed taking these factors into account.

Determination of Melamine in Milk by Fluorescent Spectrophotometry with Cetyltrimethylammonium Bromide / 分析化学

Melamine is a kind of triazine compound and the fluorescence of it can get enhanced in the presence of cationic surfactant in weak alkaline medium. A new fluorescent spectrophotometry based on this principle) has been developed to determine melamine under the optimum conditions such as Tris-HCl buffer solution), pH 8.0 and with CTMAB as sensitizing agent. The linear range, detection limit and relative standard deviation were 25-1000 μg/L, 19 μg/L and 1.6%,respectively. The samples were pretreated according to the solid phase extraction monolithic column to carry out the detection of real milk. This method is simple, rapid and accurate. It can be used to screen and detect the milk samples primarily.

Follow up of S3 cases of urinary calculi caused by melamine-contaminated infant milk powder / 中国综合临床

Objective To analyze the clinical features and prognosis of urinary calculi in children caused by melamine-contaminated milk. Methods Retrospective analysis of 53 cases of urinary calculi caused by melamine contaminated infant milk powder were performed. Clinical characteristics, lab measurements, colour Doppler ultrasound and CT examination results were collected, and the outcome of treatment and prognosis were followed up. Results In the 53 cases, there were 39 males and 14 females. The main clinical manifestations at admission included crying during urination, abdominal pain, hematuria, oliguria and anuria. Urine pH value was low with average of 5. 32 ±0. 25,blood uric acid was high with average of (638. 69 ±36. 25) μmol/L,blood urea nitrogen was high with average of (8. 35 ± 1. 97) mmol/L The colour Doppler ultrasound and CT examination showed calculi in both or one side kidney,or combined with calculi in both or one side ureter,calculi in one side ureter,or bladder calculi. After medical treatment,all calculi were exported,urine pH values increased to 6. 52 ±0. 47,blood uric acid blood and urea nitrogen decreased to (382. 31 ±29. 57) μmo/L and (5. 15 ±1.92) mmol/L No calculi reoccurred within one year of follow up. Conclusions Medical treatment of urinary calculi in children caused by melamine-contaminated milk powder was effective,and there were less stone recurrence after discharge.

Large sample follow-up of single centre and assessment of pediatric urolithiasis caused by melamine-contaminated milk powder / 中华肾脏病杂志

Objective To assess the prognosis and effect on renal function of pediatric urolithiasis caused by melamine-contaminated milk powder (PUMMP) in a long-term follow-up.Methods One hundred and two of 8335 children (≤ 6-year-old) with history of consuming melamine-contaminated milk powder screened in our hospital were followed up for eighteen months after diagnosis. Urinary system ultrasonography, urinalysis, urinary microprotein profiles [microalbumin (ALBU), immunoglobulin G (IgG), and N-acetyl-β-D-glucosidase (NAG)], urinary melamine and cyanuric acid were examined in the first visit and at the end of follow-up. Results Follow-up was completed in 91 children and the stone was excreted in 82 children (90.1%).Stones less than 5 mm in diameter were most vulnerable to discharge, and stones larger than 10 mm could not be expelled without interventions. At the end of follow-up, no melamine or cyanuric acid was found in the urine samples of 74 patients. Urinalysis showed that incidences of proteinuria, microscopic hematuria and leukocyturia were 0%, 5.1% and 2.0%, which were significant different from those in the first visit (Pproteinutria=0.123, Phemnatuna=0.038 and Pleukocyhuris=0.005).Urinary microprotein profiles revealed that some children whose urinalysis was normal still presented glomerular and renal tubular injury and the abnormal rates were 8.8% and 12.1%respectively. The glomerular injury was mainly related to persistent stone, male and younger.Conclusions 90.1% of children with PUMMP passes urinary stones at the end of follow-up.Stone size is the major risk factor of discharge. No melamine or cyanuric acid is found in the urine of children. After eighteen months, glomerular and renal tubular injury is still found in some patients. Further follow-up is necessary.