Screening for pectus excavatum among primary students and establishment of a pectus excavatum screening program in Dongguan, China.

OBJECTIVE: To carry out pectus excavatum (PEx) screening among primary school students in Dongguan, with an attempt to establish a PEx screening program and provide epidemiological evidences for developing guidelines on the diagnosis and treatment of PEx for young children. METHODS: A total of 479,402 primary school students who were already in school in 2012 or newly enrolled in 2013 from 422 primary schools in 32 towns in Dongguan, Guangdong Province were screened for PEx. Meanwhile, about 420 medical staff from the infirmaries of 422 primary schools were provided with a serial of training, with an attempt to establish a PEx screening program and network. RESULTS: Valid screening results were obtained from 477,627 pupils (99.62%) from 406 primary schools in 31 towns. These students aged 4-15 years (mean: 8.78 years), among whom there were 244,545 males (N1; mean age: 8.22 years) and 233,082 females (N2; mean age: 8.89 years). Totally 257 PEx patients were identified, yielding a prevalence of 0.583%, among whom there were 176 males (N3; mean age: 8.79 years) and 81 females (N4; mean age: 8.77 years). With the PEx patients as the PEx group and the healthy children as the control group, chi square test with gender as the dependent variable showed that the incidence of PEx was significantly different between male and female students (P=0.00) (N3:N4 =2.172:1). In addition, 410 medical staff from the school infirmaries were trained, and a PEx screening program and network was established. CONCLUSIONS: The screening for PEx was successfully performed among pupils who were already in school in 2012 or newly enrolled in 2013 from 422 primary schools in Dongguan, Guangdong Province. Statistical analysis showed that the incidence of PEx differed between male and female pupils. A stable effective PEx screening program was established, which will provide personal and technical supports for the early diagnosis and treatment of this condition.

Trivalent chromium and aluminum affect the thermostability and conformation of collagen very differently.

Ultrasensitive differential scanning calorimetry (US-DSC) was used to directly measure the thermal transition temperature and energy change of acid soluble collagen in the presence of Cr(3+) and Al(3+) sulfates. The behavior of Cr(3+) was analogous to kosmotropes in the cation Hofmeister series and increased the stability of collagen in dilute solutions. Meanwhile, the denaturational enthalpy change (ΔH) of collagen was substantially reduced with change to increasing Cr(3+) concentration. This is likely due to the uni-point binding of Cr(3+) with carboxyl groups of collagen side chains that could decrease the hydrogen-bonding in collagen and result in the increase of protein hydrophobicity. In the case of Al(3+), the interactions between the ions and collagen showed very different properties: at low and medium ion concentrations, the stability of the collagen was decreased; however, a further increase of Al(3+) concentration led to a salting-out effect of collagen, indicating the Al(3+) is a typical chaotropic ion. This striking difference of the two ions in the stabilization of collagen can be explained in terms of the different interactions between the cations and the carboxyl groups of collagen side chains. Additionally, we studied metal ion induced conformational change by the combination of circular dichroism (CD) and atomic force microscopy (AFM). CD measurements revealed that neither metal ion interactions of collagen with Cr(3+) nor Al(3+) ions destroyed the triple-helical backbone structure of collagen in the solution. AFM results further confirmed that the dehydration of collagen by Cr(3+) is more significant than Al(3+), thus inducing the aggregation of collagen fibrils.

Ultrasonic irradiation in the enzymatic extraction of collagen.

The application of ultrasonic irradiation (40KHz, 120W) in the enzymatic extraction of bovine tendon collagen has been investigated. Our results show that using the ultrasonic irradiation increases the yield of collagen up to approximately 124% and significantly shortens the extraction time in comparison with the conventional pepsin isolation method. Such improvements are attributed to the enhancement of the enzyme activity and the dissolution of collagen substrate because the ultrasonic irradiation disperses the pepsin aggregates and opens up the collagen fibrils, thus the enzymatic hydrolysis is facilitated. AFM imaging shows the same fibrillar structure of tendon collagens generated from both the methods. The CD and FT-IR measurements reveal that the triple helix structure of collagen remains intact even after the ultrasonic irradiation. This study shows that the mild ultrasound irradiation can effectively improve the efficiency of pepsin extraction of natural collagen without any compromise of the resultant collagen quality.