[Analysis of the whole genome traceability and transmission path simulation experiment of the local cluster COVID-19 epidemic].

Objective: To trace and characterize the whole genome of SARS-CoV-2 of confirmed cases in the outbreak of COVID-19 on July 31, 2021 in Henan Province. Method: Genome-wide sequencing and comparative analysis were performed on positive nucleic acid samples of SARS-CoV-2 from 167 local cases related to the epidemic on July 31, 2021, to analyze the consistency and evolution of the whole genome sequence of virus. Results: Through high-throughput sequencing, a total of 106 cases of SARS-CoV-2 whole genome sequences were obtained. The results of genome analysis showed that the whole genome sequences of 106 cases belonged to the VOC/Delta variant strain (B.1.617.2 clade), and the whole genome sequences of 106 cases were shared with the genomes of 3 imported cases from Myanmar admitted to a hospital in Zhengzhou. On the basis of 45 nucleotide sites, 1-5 nucleotide variation sites were added, and the genome sequence was highly homologous. Conclusion: Combined with the comprehensive analysis of viral genomics, transmission path simulation experiments and epidemiology, it is determined that the local new epidemic in Henan Province is caused by imported cases in the nosocomial area, and the spillover has caused localized infection in the community. At the same time, it spills over to some provincial cities and results in localized clustered epidemics.

[Predictive value of complement and coagulation indicators in sepsis related acute kidney injury].

Objective: To explore the predictive value of complement and coagulation indicators in sepsis related acute kidney injury (AKI). Methods: Clinical data of 217 patients with sepsis admitted to the Department of Internal Medicine and Intensive Care Unit of Affiliated Hospital of Jiangnan University from January 2018 to June 2019 were retrospectively analyzed. All patients were divided into sepsis with AKI group and without AKI group. Laboratory indicators of all patients were collected, including complement C3, complement C4, activated partial thrombin time (APTT), prothrombin time (PT), international normalized ratio (INR), D-dimer, procalcitonin(PCT), etc. logistic regression analysis was used to explore the risk factors of sepsis related AKI. Receiver operating characteristic curve (ROC) was used to evaluate the predictive value of independent risk factors. Results: Among 217 patients, 120 patients developed sepsis related AKI and 97 patients didn't. PCT, lactic acid, PT, APTT, INR and D-dimer in AKI patients were significantly higher than those without AKI (P<0.01). Complement C3 and complement C4 were significantly lower in AKI group (P<0.01). Multivariate logistic regression analysis suggested that blood pressure<90/60 mmHg (1 mmHg=0.133 kPa)(OR=3.705, 95%CI 1.536-8.934,P=0.004), increased lactic acid (OR=1.479, 95%CI 1.089-2.008, P=0.012), decreased complement C3 (OR=0.027, 95%CI 0.005-0.152, P<0.001) and prolonged APTT (OR=1.090, 95%CI 1.047-1.137,P<0.001)were independent risk factors predicting AKI. The area under the ROC curve (AUC) of these multivariates were 0.741 (95%CI 0.675-0.807), 0.798 (95%CI 0.732-0.864), 0.712 (95%CI 0.643-0.781) and 0.716 (95%CI 0.648-0.783) respectively. The relevant sensitivity was 57.5%, 80.8%, 87.5%, 59.2%, and the specificity was 90.7%, 75.3%, 51.5%, 77.3%, respectively. The AUC of the combined four indicators was 0.880 (95%CI 0.835-0.926) with the sensitivity 75.0% and the specificity 90.7%. Conclusion: The low level of complement C3 and prolonged APTT predict sepsis related AKI, and the predictive value can be enhanced if hypotension and hyperlactacidemia are added.

[Determination of methyl ethyl ketone in urine by headspace gas chromatography].

Objective: To establish a method for determination of methyl ethyl ketone in urine by headspace gas chromatography. Methods: In the urine sample(hereinafter referred to as urine sample), methyl ethyl ketone is pretreated by headspace technology, and a certain amount of head air is injected into the gas chromatograph, separated by capillary column, detected by hydrogen flame ionization detector, and the retention time is qualitative and the peak height is high. Peak area. Results: Good linearity was in the range of 0.01 to 6.0 µg/ml with a regression equation of y=13.316x+0.8497 and γ=0.9997.The minimum detectable concentration of methyl ethyl ketone was 0.01 µg/ml. The range intra-day RSD and inter-day RSD were 2.2%-5.5% and 2.5%-6.1% respectively. Urine samples can be stored for 20 days in the refrigerator at 4 ℃. Conclusion: The method has a high advantage of sensitivity and accuracy, and also easy to operate. Therefore, it is suitable for the determination of methyl ethyl ketone in urine.

[Expression level and clinical significance of LncRNA HOXA11-AS in esophageal squamous cell carcinoma patients].

Objective: To explore the expression of long noncoding RNA (lncRNA) HOXA11-AS in esophageal squamous cell carcinoma tissues and the relationship of HOXA11-AS level with clinical outcomes. Methods: Quantitative real-time polymerase chain reaction (qRT-PCR) was applied to detect the expression level of HOXA11-AS in cell lines HET-1A, EC9706, EC109, and in tumor tissue and paired adjacent tissue samples from 73 ESCC patients who received surgical resection.The correlations of the expression level of HOXA11-AS with clinicopathological features and prognosis were also analyzed. Results: The relative expression levels of HOXA11-AS in tumor tissue and paired adjacent tissue were 0.832±0.387 and 2.486±1.087, respectively, with significant difference (P<0.001). The expression of HOXA11-AS was upregulated in 63.0%(46/73)ESCC tissues. The relative expression levels of HOXA11-AS in HET-1A, EC-9706 and EC-109 cells were 1.000, 23.553±3.221 and 17.217±1.968, respectively. The expression level of HOXA11-AS was upregulated in ESCC cell lines (P<0.001). High expression level of HOXA11-AS was correlated with histological grade and lymph node metastasis of ESCC patients (P<0.05). However, it was not associated with the age, gender, depth of infiltration and TNM staging (P>0.05). The median overall survival (OS) and median disease-free survival (DFS) of patients with low HOXA11-AS expression were 43 months and 42 months, respectively, significantly longer than 37 months and 28 months of patients with HOXA11-AS high expression (P<0.05). Cox model multivariate analysis showed that the expression of HOXA11-AS and lymph node metastasis were independent factors of poor prognosis of ESCC patients. Conclusions: The expression of HOXA11-AS is upregulated in esophageal cancer cell lines and tissues. High expression of HOXA11-AS is associated with poor prognosis of ESCC patients.Therefore, LncRNA HOXA11-AS may serve as a predictive marker of postoperative ESCC patients.

[Determination of diethyl phthalate in the air of workplace by gas chromatography].

Objective: To establish a method for the determination of diethyl phthalate by gas chromatography in the air of workplaces. Methods: Diethyl phthalate in the air of workplace was collected throµgh glass fiber filter, eluted with methylbenzene, and detected by gas chromatography coupled with FID detectors. Results: The linear range of diethyl phthalate determined by this method was 14.0~1 400 µg/ml, y=2.09801x-3.66229, and the coefficient correlation was 0.999 99. The detection limit was 1.10 µg/ml, and the minimum detection concentration was 0.18mg/m(3) (collected sample volume was 30 L) . The within-run precisions were 1.04%~2.75%, and the between-run precisions were 0.34%~1.30%. The recovery rates were 98.72%~103.21%, and sampling efficiency was 97.2%~100.0%. The elution efficiencies were 97.25%~98.68%. The samples could be stored at room temperature for 15 days. Conclusion: The indicators established in this study were conformed with the requirements of GBZ/T210.4-2008, "The Guidelines for the Development of Occupational Hygiene Standards Methods Part 4: Determination of Chemical Substances in the Air of Workplaces" . Diethyl phthalate in the workplace air could be rapidly collected, accurate separated and determinated. This method is applicable to the determination of diethyl phthalate in the workplace air.

[A clinical analysis of 123 cases of primary empty sella].

Objective: This study was conducted to analyze the clinical characteristics and pituitary function of patients with primary empty sella (PES). Methods: The clinical data from 123 hospitalized adult patients with PES from January 2010 to May 2016 were retrospectively studied. Results: (1) The average age of the 123 (male 43, female 80) PES patients was (59.2±13.6) years (ranging 24-92 years), among whom 61% patients were in the age group between 50-69 years. (2) The symptoms of the patients included fatigue (56.1%), headache (34.1%), nausea and vomiting (17.9%), gonadal dysfunction (17.1%), visual disturbance (5.7%) and hypopituitarism crisis (3.3%). (3) Hypopituitarism was found in 66 of the 123 patients. Among them, 36.6%, 31.7% and 17.1% were central hypoadrenalism, hypogonadism, and hypothyroidism, respectively.The percentage of hypopituitarism in complete PES was significantly higher than that in partial PES (P<0.05). (4) Sixteen patients were concomitant with other autoimmune diseases including 11 patients with Graves' disease and 2 with Cushing's syndrome due to adrenal adenoma. Conclusions: The incidence of hypopituitarism in PES was 53.7%, in which the pituitary-adrenal axis hypofunction was more common. An overall evaluation of the pituitary function was essential for the patients who had headache and fatigue, or with suspected PES. The patients with hypopituitarism should be given hormone replacement therapy in time and followed up afterword.

[Determination of tributyl phosphate in the air of workplace by gas chromatography].

Objective: To establish a practical method forsampling and detectingtributyl phosphate intheworkplace. Methods: The samples were extracted by glass fiber membrane, eluted with ether, separated by gas chromatography, and detected by flame photometric detector. Results: There were good linear relationship in the minimum detection concentration was 7.2-720.0 µg/ml, and the correlation coefficient was 0.999 92. The detection limit was 0.86 µg/ml, and the minimum detection concentration was 0.14 mg/m(3) (sample volume was 30 L) . Recovery rates were 99.8%-100.2%. The with-in relative standard deviations were 4.0%-5.4% and the between relative standard deviations were 2.0%-5.5%, and average samplingefficiency was about 99.1%-100.0%. Conclusion: This method conforms with the requirements of "Standardization of Methods for Determination of Toxic Substance in Workplace" . Tributyl phosphate in air could be determined accurately using this method.

[The effect of occupational exposure to coal tar pitch workers' health].

Objective: To investigate the effect of occupational exposure to coal tar pitch on workers' health and metabolism. Methods: 805 workers exposed to coal tar pitch were selected as exposure group from the produce and em-ploy factory. Other people handle administrative and logistical affairs who not exposed to coal tar pitch were selected as control group. Fix-point sample of air were collected to detect the concentration of coal tar pitch. Do physical examination and questionnaire to collect workers' basic and healthy information. To detect the metabolic product of urine samples in laboratory. Results: Anomaly detection rate of the skin in exposure group is 10.61. The lung function indices (FEV1.0%) in exposure group were significantly lower than control group (P<0.05) . The monocyte count and monocyte rate in expo-sure group were significantly higher than control group (P<0.05) . The metabolic product content of PAHS in urine sam-ples is significantly higher in exposed group than control group (P<0.05) . Conclusion: The metabolic product content of polycyclic aromatic hydrocarbon is higher in exposed workers. Coal tar pitch damage workers' skin and lung function. It can cause pruritus chromatodermatosis and so on.

Absolute group refractive index measurement of air by dispersive interferometry using frequency comb.

The absolute group refractive index of air at 1563 nm is measured by dispersive interferometry, and a combined uncertainty of 1.2 × 10(-8) is achieved. The group refractive index of air is calculated from the dispersive interferograms of the two beams passing through the inner and outer regions of a vacuum cell by fast-Fourier-transform. Experimental results show that the discrepancies between our method and modified Edlén equation are less than 3.43 × 10(-8) and 4.4 × 10(-8) for short-term and long-term experiments, respectively. The interferogram update rate is 15 ms, which makes it suitable for application of real-time monitoring. Furthermore, it is promising to improve the measurement uncertainty to 3.0 × 10(-9) by changing the material of the vacuum cell and measuring its length more accurately through optical interferometry.

Rapid sedation induced by fentanyl combined with propofol via an intrathecal chemotherapy injection for leukemia in children.

This study explored the sedative and analgesic effects of fentanyl combined with propofol via an intrathecal chemotherapy injection for acute leukemia (acute lymphocytic leukemia or acute myelocytic leukemia) among children, to relieve pain and difficulty during intrathecal injection, improve treatment compliance, increase the success rate of single puncture, and reduce procedure failure, with the aim of developing a painless procedure for children with acute leukemia. Fifty person-times received fentanyl combined with propofol via an intrathecal chemotherapy injection among the hospitalized children with leukemia. The patients' cooperation with the procedure, response to the medication, dosages of fentanyl and propofol, reaction to the procedures, wake-up time, and changes in oxygen saturation (SpO2), heart rate (HR), respiration, and blood pressure (BP) before, during, and after the procedures were observed. The doctors who performed the procedures assessed the quality of sedation and analgesia. In the treatment group, the patients were quiet during the lumbar puncture and intrathecal injection, showing good sedation and analgesia. HR and respiration decreased slightly. There were no changes in SpO2 and BP. No obvious respiratory depression occurred with proper dosages. Only a few patients showed stertorous respiration, which stopped soon after the procedures. In the control group, the patients were agitated, crying, and not cooperative before and during the procedures, which made the procedures very difficult. During intrathecal injection, pain obviously reduced and the success rate of single lumbar puncture increased. It is safe and effective to apply fentanyl combined with propofol for sedation and analgesia.

[Research advances on application of sub-epidermal moisture scanner in monitoring tissue viability of early pressure injuries].

Pressure injury (PI) not only reduces the quality of life of patients but also is expensive to manage, placing a heavy financial burden on patients and their families, and society. Despite the increasing diversity of methods used to identify early PI, there are still few methods that can truly and accurately predict early PI. The sub-epidermal moisture scanner is the first U.S. Food and Drug Administration-authorized PI management device that can predict the occurrence and development of PI by measuring the level of local tissue bio-capacitance and monitoring the tissue viability. As an emerging diagnostic instrument, the sub-epidermal moisture scanner has already shown great advantages in clinical practice, which can promote the informatization, digitization, and intelligent prevention and management of PI. This paper introduces the pathophysiological mechanism of PI, elucidates the working principle and parameter settings of the sub-epidermal moisture scanner, its clinical application in monitoring tissue viability in early PI, and its limitation, and looks forward to its future development.

Lightning on Venus inferred from whistler-mode waves in the ionosphere.

The occurrence of lightning in a planetary atmosphere enables chemical processes to take place that would not occur under standard temperatures and pressures. Although much evidence has been reported for lightning on Venus, some searches have been negative and the existence of lightning has remained controversial. A definitive detection would be the confirmation of electromagnetic, whistler-mode waves propagating from the atmosphere to the ionosphere. Here we report observations of Venus' ionosphere that reveal strong, circularly polarized, electromagnetic waves with frequencies near 100 Hz. The waves appear as bursts of radiation lasting 0.25 to 0.5 s, and have the expected properties of whistler-mode signals generated by lightning discharges in Venus' clouds.

Pathway for the elimination of melamine in lactating dairy cows.

Melamine might be degraded into cyanuric acid and some other analogs by the rumen microorganism. Thus, the metabolism of melamine in ruminants may be different from that in monogastric animals. The objective of this study was to investigate the pathway for the elimination of melamine in lactating dairy cows. Four late-lactation dairy cows (body weight=524±17 kg, days in milk=265±14 d) fitted with ruminal cannulas were dosed with melamine (purity ≥99.5%) at 800 mg/d per cow that divided into 2 equal daily doses. The trial lasted for 20 d (13-d preliminary period, followed by a 7-d sample-collecting period). The method of liquid chromatography and tandem mass spectrometry was used to determine melamine and cyanuric acid contents simultaneously. Before the trial started, no melamine or cyanuric acid was detected in samples of total mixed ration, milk, plasma, urine, and feces. The melamine concentration in rumen fluid (Y, mg/L) decreased exponentially after the morning feeding (X, h) (Y=3.85591e(-X/9.25674)+1.35924, R(2)=0.99), but no cyanuric acid was detected. Plasma melamine concentration (0.296±0.014 mg/L) was relatively stable in the 3 different sampling times. The percentages of melamine excreted through milk, urine, and feces were 0.48±0.06, 44.07±10.79 and 10.98±3.88%, respectively. It could be inferred that 44.47±7.98% of ingested melamine was degraded in the rumen, because cyanuric acid was detected in plasma, urine, and feces on the condition that no melamine was contained in the total mixed ration fed to the dairy cows. The results of the present study implied that the elimination pathway of melamine in lactating dairy cows was different from that in monogastric animals. A high percentage of melamine was degraded into cyanuric acid gradually by rumen microorganisms. Most ingested melamine was excreted in urine and feces, which are the main elimination pathways for melamine in lactating dairy cows.

Effect of incremental levels of fish oil supplementation on specific bacterial populations in bovine ruminal fluid.

The objective of this study was to determine the effects of incremental replacement of dietary linoleic acid by >20-carbon polyunsaturated fatty acids (PUFA) on changes in population of ruminal micro-organisms associated with fibre digestion and biohydrogenation using real-time PCR of bacterial 16S rRNA sequences. Four beef steers with ruminal cannulas were randomly assigned to control (CK, 65:35 forage to concentrate), CK with 3% sunflower oil plus 1% fish oil (S3F1), 2.5% sunflower oil plus 1.5% fish oil (S2.5F1.5) or 2% sunflower oil plus 2% fish oil (S2F2) in a 4 × 4 Latin square design with 21-day periods. Ruminal fluid was collected on day 15 of each period. Compared with CK, oil addition led to lower ruminal acetate and butyrate but greater propionate concentration. DNA copy number of Anaerovibrio lipolytica in ruminal fluid was greater with oil (average 5.38 vs. 3.62 × 10(5) DNA copy number), particularly with S2F2 relative to CK. Fibrobacter succinogenes and Butyrivibrio fibrisolvens DNA copy number decreased by 74% (1.06 vs. 4.01 × 10(5)) and 39% (5.16 vs. 8.42 × 10(7)) in response to S2F2 compared with CK. DNA copy numbers of Ruminococcus flavefaciens and Ruminococcus albus were not affected by incremental fish oil. Results suggest that greater availability of PUFA with >20 carbons (i.e. eicosapentaenoic acid and docosahexaenoic acid) promoted changes in bacterial populations that are relevant for fibre digestion and biohydrogenation.

[Clinical analysis of 4 children with hereditary hypercholesterolemia].

Objective: To investigate the clinical characteristics of hereditary hypercholesterolemia in childhood. Methods: The clinical data including general conditions, clinical manifestations, laboratory tests, and genetic testing results of 4 children with hereditary hypercholesterolemia who admitted to Henan Children's Hospital from January 2020 to December 2020 were retrospectively analyzed. Results: There were 4 female children aged 5.5,1.5,6.3,3.1 years, all presented with skin xanthoxoma as the chief complaint. Plasma total cholesterol (range 11.8 to 20.9 mmol/L) and low density lipoprotein-cholesterol (range 8.2 to 13.7 mmol/L) were significantly elevated. The serum ß-glutamate levels in case 1 (241.2 µmol/L) and case 2 (164.2 µmol/L) increased significantly. Genetic analysis revealed compound heterozygous variants of ABCG8 gene in case 1 and ABCG5 gene in case 2 who were diagnosed with sitosterolemia. Case 3 and 4 who all had family history of hypercholesterolemia and compound heterozygous variants of LDLR gene were diagnosed with familial hypercholesterolemia. After diet treatment, the blood lipids returned normal and the skin xanoma subsided in case 1 and 2. In case 3 and 4, the blood lipids gradually decreased after diet and rosuvastatin treatment. Conclusions: Xanthomatosis is the common clinical manifestation of sitosterolemia and familial hypercholesterolemia. Family history, blood plant sterol profile, genetic variation, and changes in blood lipids after early dietary treatment are helpful for disease identification.

[Relationship between body mass index and sexual development in Chinese children].

Objective: To investigate the relationship between body mass index (BMI) and sexual development in Chinese children. Methods: A nationwide multicenter and population-based large cross-sectional study was conducted in 13 provinces, autonomous regions and municipalities of China from January 2017 to December 2018. Data on sex, age, height, weight were collected, BMI was calculated and sexual characteristics were analyzed. The subjects were divided into four groups based on age, including ages 3-<6 years, 6-<10 years, 10-<15 years and 15-<18 years. Multiple Logistic regression models were used for evaluating the associations of BMI with sexual development in children. Dichotomous Logistic regression was used to compare the differences in the distribution of early and non-early puberty among normal weight, overweight and obese groups. Curves were drawn to analyze the relationship between the percentage of early puberty and BMI distribution in girls and boys at different Tanner stages. Results: A total of 208 179 healthy children (96 471 girls and 111 708 boys) were enrolled in this study. The OR values of B2, B3 and B4+ in overweight girls were 1.72 (95%CI: 1.56-1.89), 3.19 (95%CI: 2.86-3.57), 7.14 (95%CI: 6.33-8.05) and in obese girls were 2.05 (95%CI: 1.88-2.24), 4.98 (95%CI: 4.49-5.53), 11.21 (95%CI: 9.98-12.59), respectively; while the OR values of G2, G3, G4+ in overweight boys were 1.27 (95%CI: 1.17-1.38), 1.52 (95%CI: 1.36-1.70), 1.88 (95%CI: 1.66-2.14) and in obese boys were 1.27 (95%CI: 1.17-1.37), 1.59 (95%CI: 1.43-1.78), and 1.93 (95%CI: 1.70-2.18) (compared with normal weight Tanner 1 group,all P<0.01). Analysis in different age groups found that OR values of obese girls at B2 stage and boys at G2 stage were 2.02 (95%CI: 1.06-3.86) and 2.32 (95%CI:1.05-5.12) in preschool children aged 3-<6 years, respectively (both P<0.05). And in the age group of 6-10 years, overweight girls had a 5.45-fold risk and obese girls had a 12.54-fold risk of B3 stage compared to girls with normal BMI. Compared with normal weight children, the risk of early puberty was 2.67 times higher in overweight girls, 3.63 times higher in obese girls, and 1.22 times higher in overweight boys, 1.35 times higher in obese boys (all P<0.01). Among the children at each Tanner stages, the percentage of early puberty increased with the increase of BMI, from 5.7% (80/1 397), 16.1% (48/299), 13.8% (27/195) to 25.7% (198/769), 65.1% (209/321), 65.4% (157/240) in girls aged 8-<9, 10-<11 and 11-<12 years, and 6.6% (34/513), 18.7% (51/273), 21.6% (57/264) to 13.3% (96/722), 46.4% (140/302), 47.5% (105/221) in boys aged 9-<10, 12-<13 and 13-<14 years, respectively. Conclusions: BMI is positively correlated with sexual development in both Chinese boys and girls, and the correlation is stronger in girls. Obesity is a risk factor for precocious puberty in preschool children aged 3-<6 years, and 6-<10 years of age is a high risk period for early development in obese girls.

Magnetic Field Annihilation in a Magnetotail Electron Diffusion Region With Electron-Scale Magnetic Island.

We present observations in Earth's magnetotail by the Magnetospheric Multiscale spacecraft that are consistent with magnetic field annihilation, rather than magnetic topology change, causing fast magnetic-to-electron energy conversion in an electron-scale current sheet. Multi-spacecraft analysis for the magnetic field reconstruction shows that an electron-scale magnetic island was embedded in the observed electron diffusion region (EDR), suggesting an elongated shape of the EDR. Evidence for the annihilation was revealed in the form of the island growing at a rate much lower than expected for the standard X-type geometry of the EDR, which indicates that magnetic flux injected into the EDR was not ejected from the X-point or accumulated in the island, but was dissipated in the EDR. This energy conversion process is in contrast to that in the standard EDR of a reconnecting current sheet where the energy of antiparallel magnetic fields is mostly converted to electron bulk-flow energy. Fully kinetic simulation also demonstrates that an elongated EDR is subject to the formation of electron-scale magnetic islands in which fast but transient annihilation can occur. Consistent with the observations and simulation, theoretical analysis shows that fast magnetic diffusion can occur in an elongated EDR in the presence of nongyrotropic electron effects. We suggest that the annihilation in elongated EDRs may contribute to the dissipation of magnetic energy in a turbulent collisionless plasma.

Residues of melamine and cyanuric acid in milk and tissues of dairy cows fed different doses of melamine.

Melamine (1,3,5-triazine-2,4,6-triamine) may be degraded into cyanuric acid and some other compounds by rumen microorganisms. This study was conducted to assess the transfer of melamine and cyanuric acid in to milk and tissues by dairy cows fed different doses of melamine. Forty mid-lactation dairy cows (157±43 d in milk, 20.8±1.4 kg of milk/d) were divided into 4 groups (n=10/group) using a completely randomized design. The groups were fed the following amounts of melamine (purity ≥99.5%) at 0 (control), 300 [treatment (Trt) 1], 500 (Trt 2), and 1,000 (Trt 3) mg/d per cow, respectively. The trial lasted for 18 d (12-d feeding period, followed by a 6-d clearance period). Milk samples were collected from the 4 groups on d 1, 2, 3, 4, 8, 12, 13, 14, 15, and 18, and analyzed for melamine and cyanuric acid. On d 13, 3 cows from Trt 2 and Trt 3 were randomly selected and slaughtered; tissue samples including kidney, liver, mammary, bladder, gluteus medius, and longissimus dorsi were collected for melamine and cyanuric acid analyses. Milk and tissue samples were analyzed for melamine and cyanuric acid using a simultaneous liquid chromatography tandem mass spectrometry procedure. Neither melamine nor cyanuric acid was detected in concentrated feed that was being fed to the cows. In melamine-treated groups, milk melamine concentration increased quickly and reached a stable level by d 4 and was at similar levels on d 8 and 12 after the first administration of melamine. Milk melamine levels in treated groups were 0.18, 0.27, and 0.50mg/L for Trt 1, Trt 2, and Trt 3, respectively, and were highly correlated (R(2)=0.91) with melamine dosing levels. No cyanuric acid was detected in any of the milk collected from the various groups. Melamine residue levels in tissues of Trt 3 were about 2-fold higher than that in Trt 2, with the highest concentration being found in kidney. No differences in cyanuric acid levels in tissues were found between Trt 3 and Trt 2. Liver, kidney, and bladder tissues were found to contain the highest cyanuric acid levels. This study shows a relationship between dietary melamine levels and cyanuric acid levels found in tissues, which might be the result of melamine being converted to cyanuric acid by microorganisms in the rumen.