Phthalate exposure linked to high blood pressure in Chinese children.

BACKGROUND: Exposure to phthalate esters may be linked to the risk of high blood pressure (HBP), but limited evidence is available in Chinese children. OBJECTIVE: To investigate the associations between nine phthalate metabolites (mPAEs) and systolic/diastolic BP, pulse pressure (PP), mean arterial pressure (MAP), and the risk of HBP. METHODS: In this cross-sectional study, a total of 1044 primary school children (6-8 years old) were enrolled from Shenzhen, China, between 2016 and 2017. Nine mPAEs were analyzed from urine using ultra-performance liquid chromatography and tandem mass spectrometry. A multivariable linear regression model was used to explore the associations between phthalate exposure and systolic/diastolic BP, PP, and MAP. A binary logistic regression model was used to examine the associations between phthalate exposure and the risk of HBP. RESULTS: Monomethyl phthalate (MMP) concentrations were significantly higher in HBP children than normal BP children. MMP, monoisobutyl phthalate (MiBP), monobutyl phthalate (MnBP), mono(5-carboxy-2-ethylpentyl) phthalate, mono-[(2-carboxy methyl)hexyl] phthalate (MCMHP), the sum of four short-chain mPAEs (∑LMW), and the sum of all nine mPAEs (∑9mPAEs) were significantly positively associated with increases in systolic BP z-score, while only MMP was significantly positively associated with diastolic BP z-score. MMP, MiBP, MnBP, MCMHP, ∑LMW, and ∑9mPAEs were significantly associated with increases in PP, while MMP and MnBP were significantly associated with increases in MAP. MMP was significantly associated with the risk of HBP, with an odds ratio of 1.87 (95% CI: 1.23, 2.85). CONCLUSIONS: The present study suggests that dimethyl phthalate exposure increases the risk of HBP. And some types of phthalates are associated with elevations in systolic/diastolic BP z scores, PP, and MAP in Chinese children.

[A static mechanical comparison between two transarticular internal fixation techniques in the lower cervical spine].

OBJECTIVE: To compare static mechanical difference between two transarticular internal fixation techniques in the lower cervical spine. METHODS: Ten fresh human cadaveric cervical spines were harvested. On one side, transarticular pedicle screws were placed at the C3-4, C5-6, and C7-T1 levels, and transarticular screws were placed on the other side. The screw insertion technique at each level was randomized for right or left. The starting point for transarticular pedicle screw insertion was located at the midpoint of the inferolateral quadrant of the lateral mass and the direction of the screw was about 50 degrees caudally in the sagittal plane and about 45 degrees medially in the axial plane, and the starting point for transarticular screw insertion was 1 mm medial to the midpoint of the lateral mass, aiming in a 15 - 20 degrees caudally and 35 - 40 degrees lateral position. After screw placement, each set of vertebral bodies were mounted in a custom jig for axial pullout testing using a servohydraulic testing machine. The load-displacement curves were obtained for each screw pullout. RESULTS: The mean pullout strength for the transarticular pedicle screws was 668 N. This compares with 414 N for the transarticular screws (P < 0.05), but there was not significant difference statistically between different cervical levels (P > 0.05). CONCLUSION: The static mechanical strength of transarticular pedicle screws is superior to the transarticular screws, and the transarticular pedicle screw fixation has the biomechanical feasibility of clinical application.