The attention is often paid toknowledge processing procedure including knowledge acquisition,knowledge expression and knowledge utilization when expert system is studied and designed.The knowledge expression is the most basic topic among them.Knowledge expression system and its application tomedical diagnosis computer-aided system are discussed in this paper.

Objective To analyze the risk factors for the external hydrocephalus (EH) after traumatic brain injury in the infants. Methods The clinical data of 178 cases of infants and young children with traumatic brain injury from March 2004 to April 2009 were retrospectively analyzed. Univariate and logistic regression analysis were performed to identify the clinical risk factors for EH after traumatic brain injury. Results By univariate regression analysis, age, GCS score after trauma, coma duration, brain contusion, subarachnoid hemorrhage and epilepsy were risk factors for external hydrocephalus in the infants and young children (Ps < 0.05). Gender,traumatic wet lung and usage of mannitol were less relevant to EH (Ps >0. 05). The incidence of EH after traumatic brain injury in the infants and young children was 14% (25/178 ). Age ( OR = 0.5743 ) , coma duration after trauma (OR =3.0628) ,subarachnoid hemorrhage (OR =3.7093),brain contusion(OR = 4.7892) and post-trauma epilepsy (OR =2. 9976) were risk factors for EH (Ps < 0. 05). Conclusion Younger than 2 years old, low GCS score, long coma duration, brain contusion, subarachnoid hemorrhage and epilepsy would increase the risk of EH after traumatic brain injury in the infants and young children. This study provides information for the prevention of EH after traumatic brain injury in the infants and young children.

OBJECTIVETo study the precise stress distribution of the apical foramen area of endodontic endosseous implant, in order to improve the prosthetics of endodontic endosseous implant.

METHODSAfter analysis of the two-dimensional endodontic endosseous implants model with finite element method, left and right areas beside the apical foramen were selected as infinite domains to calculate. D-N interactive method was used to connect the finite and infinite domains.

RESULTSUnder 45 degrees axial right oblique loading, the stress concentration occurred in both infinite domains of the apical foramen. The infinite domain nearing the load side was tension stress concentration, but the other side was compressive stress concentration. Two stress concentration points were just at the central points, which were intersections between implant and dentin. The stress reduced in all directions from these two stress concentration points, but in the ligament, the result was contrary.

CONCLUSIONSThe change of the tooth rotational center is helpful to the tooth stability and carrying capacity after restoration. In the implant area, the diameter of implant at the apical foramen of root shall not be reduced to protect root in clinical work. It is very important to preserve the tissue of periodontal ligament for endodontic endosseous implants.

Dental Implantation, Endosseous ; Dental Models ; Dental Stress Analysis ; methods ; Humans

Objective:To evaluate the activity of iduronate-2-sulfatase (IDS) in fetal villi and peripheral blood plasma of pregnant women at high risk of mucopolysaccharidosis type Ⅱ (MPS Ⅱ), and to discuss the application of gene analysis in prenatal diagnosis of MPS Ⅱ.Methods:The enzymatic testing and gene analysis results of 23 pregnant women at high risk of MPS Ⅱ, who underwent prenatal diagnosis in Guangzhou Women and Children′s Medical Center from February 2013 to December 2020, were analyzed retrospectively.The IDS activity in fetal villi (30 cases) and plasma (28 cases) was detected by artificial substrate fluorescence.The IDS activity in fetal villi (28 cases) and plasma (34 cases) of normal pregnant women was taken as control.Meanwhile, the fetal villi of both pregnant women at high risk of MPS Ⅱ and normal pregnant women were also analyzed by gene testing and for fetal sex identification.Data were compared between groups by the independent samples t test. Results:The normal reference values of the IDS activity in fetal villi and plasma of normal pregnant women were(71.2±23.4) nmol/(mg·4 h) and (611.1±114.5) nmol/(mL·4 h), respectively.Among the 30 cases of high-risk fetal villi, the IDS activity in fetal villi of 8 affected male fetuses was (1.7±0.3) nmol/(mg·4 h), which was significantly lower than that of 11 unaffected male fetuses (83.2±6.3) nmol/(mg·4 h) and that of 9 non-carrier female fetuses (80.0±7.5) nmol/(mg·4 h) ( t=10.8, 8.8; all P<0.01). Meanwhile, the IDS activity was measured in the maternal peripheral plasma of 28 pregnant women at high risk of MPS Ⅱ.Among them, the IDS activity in 8 affected male fetuses was(225.4±20.5) nmol/(mL·4 h), which was significantly lower than that in non-affected male fetuses[(451.0±15.1) nmol/(mL·4 h)] and that in non-carrier female fetuses[(467.7±45.3)nmol/(mL·4 h)]. Eight known pathogenic mutations were found in 30 cases at high risk of MPS Ⅱ of fetal villi, and the mutation types were c. 1048A>C, c.212G>A, c.514C>T, c.257C>T, c.425C>T, and c. 998C>T.Of the 8 cases, 6 affected male fetuses had significantly reduced IDS activities, and the other 2 female carriers had normal IDS enzyme activities. Conclusions:The IDS activity in fetal villi and peripheral plasma of pregnant woman is consistent with the gene analysis results.The IDS activity has an important reference value for the prenatal diagnosis of MPS Ⅱ in the first trimester.When no genetic mutations are found in the probands or the pathogenicity of the new mutation remains unclear, the IDS activity in fetal villi can be detected separately for the prenatal diagnosis of MPS Ⅱ.

To investigate the clinical manifestations, molecular genetics and gonadal pathology characteristics of patients with disorders of sex development (DSD), and to summarize the clinical experience of identifying rare diseases from common symptoms.

The clinical data of 416 patients with DSD diagnosed and treated in the multidisciplinary center of DSD of Guangzhou Women and Children′s Medical Center from May 2018 to August 2023 were retrospectively analyzed, summarized and discussed.

According to chromosome karyotype, 416 cases of DSD were classified into three types: 92 cases(22.1%) of abnormal sex chromosome karyotype, 285 cases(68.5%) of 46, XY karyotype and 39 cases(9.4%) of 46, XX karyotype. Among the 92 patients with abnormal sex chromosome karyotype, 59 cases were raised as males, 18 cases (30.5%) complained of short penis with hypospadias and cryptorchidism. The most common karyotype was 45, X/46, XY(58 cases, 63.0%).Among the 285 patients with 46, XY karyotype, 238 cases were raised as males, and 63 cases(26.5%)complained of short penis and hypospadias; 47 cases were raised as females, and 13 cases(27.7%) complained of inguinal mass. A total of 216 patients with 46, XY karyotype were subjected to whole exome gene detection, and 155 cases(71.8%) were found to have molecular pathogenesis with the clinical phenotype. Among the 39 patients with 46, XX karyotype, 19 cases were raised as males, and 8 cases(42.1%) complained of short penis and hypospadias. In the 18 cases of gonad biopsy, 17 cases showed testicular tissue in gonads. Whole exome sequencing was performed in 14 cases. NR5A1 gene heterozygous mutation, SRY gene mutation and SOX3 gene mutation were found in 2 cases, respectively(14.3%). Twenty cases were raised as females, and 14 cases(70.0%) complained of clitoral hypertrophy. Gonad biopsy was performed in 8 cases, with 7 cases of ovotestis(87.5%) and 1 case of NR5A1 gene heterozygous mutation(14.3%).

The etiologies of DSD are complex and diverse, and the clinical manifestations are various, which can be manifested as hypospadias, micropenis, cryptorchidism and other common symptoms of the urinary system. Different etiologies have different treatment options. Therefore, chromosome karyotype, molecular genetic testing and gonadal pathology can be used to clarify the cause of disease, especially for rare diseases, improve the detection rate, reduce the rate of missed diagnosis, and ensure reasonable treatment, especially sex selection.