Objective To discuss the mechanostat of bone remodeling under dynamic loads. Methods By analysis on mechanostat of bone remodeling and absorption from the idea of mechanical fatigue strength theory, the mechanostat of bone remodeling under dynamic loads was developed. Damage was selected as the mechanical stimulus under dynamic loads and the model of bone remodeling under dynamic loads was proposed. Physical exercise for prevention and treatment of osteoporosis was simulated to analyze the biomechanical phenomenon why the osteogenesis effect under dynamic loads seems better than that under static loads. Results The biomechanical phenomenon as mentioned above was reasonably explained. An increase of 10%-30% in physical exercise could cause an increase of 3.13%-8.61% in bone mineral density. Conclusions The mechanostat of bone remodeling under dynamic loads will provide theoretical guidance for using mechanical vibration to treat or prevent diseases related to bone metabolism, which is the supplement and improvement for mechanostat of bone remodeling.

Objective To develop a mechanobiological model of bone remodeling based on stress state at cellular and molecular level. Methods Through analysis of bone remodeling process and mechanical stimulus from an engineering perspective, as well as absorption from the idea of mechanical strength design theory, the equivalent stress as the mechanical stimulus and the appropriate calculation formula of mechanical stimulus based on stress state were selected to propose a mechanobiological model of bone remodeling based on stress state at the cellular and molecular level. The model was then used to simulate bone remodeling of alveolar bone in orthodontics. Results The reduction of the vascular porosity and increase of bone mass appeared in tensile stress area, while vascular porosity increased and bone mass reduced in compression stress area, which was consistent with the features of alveolar bone. Conclusions The mechanobiological model of bone remodeling based on stress state at cellular and molecular level considered the effect of stress state on failure forms of bone tissues, embodied bone remodeling as a cellular automaton optimization process under mechanical stimulus, which would contribute to investigating effects of stress state on bone remodeling at the cellular and molecular level. The study is a supplement and improvement of bone remodeling theory and will provide theoretical guidance for treatment of orthodontics.

Objective　To establish animal model for hypertrophic scar and study the characters of its morphology and collagen metabolism. Methods　A total of 64 round wounds (diameter of 6 mm each) with total skin loss were made on the ventral side of rabbit ear using a trephine. Morphology and collagen metabolism of scar wounds were studied at 14,21,35,70 and 98 days after operation, respectively. Results　There were 76% elevated scars developed (45/59 wounds) on the ventral side of rabbit ear at 21 days and 46% elevated scars disappeared (11/24) at 98 days after operation. There were numerous fibroblast proliferation and whorl-arranged collagen fibers at 21 and 35 days. The number of fibroblast decreased, but irregular-arranged fibers still presented in the elevated scars at 70 and 98 days after operation. Hydroxyproline content in elevated scars at 21 days was higher than that in normal skin (P<0.05), and at 35 days was 3 times as that in normal skin and at 98 days was also markedly higher than that in normal skin (P<0.05). Conclusion　Excessive deposition of collagen is a characteristic of hypertrophic scar in rabbits. The conversion of normal scarring to hypertrophic scarring in rabbits occurs at 14～21 days after operation. Both development and regression of hypertrophic scar in rabbit are quicker than that in human.

Objective　To establish animal model for hypertrophic scar and study the characters of its morphology and collagen metabolism. Methods　A total of 64 round wounds (diameter of 6 mm each) with total skin loss were made on the ventral side of rabbit ear using a trephine. Morphology and collagen metabolism of scar wounds were studied at 14,21,35,70 and 98 days after operation, respectively. Results　There were 76% elevated scars developed (45/59 wounds) on the ventral side of rabbit ear at 21 days and 46% elevated scars disappeared (11/24) at 98 days after operation. There were numerous fibroblast proliferation and whorl-arranged collagen fibers at 21 and 35 days. The number of fibroblast decreased, but irregular-arranged fibers still presented in the elevated scars at 70 and 98 days after operation. Hydroxyproline content in elevated scars at 21 days was higher than that in normal skin (P<0.05), and at 35 days was 3 times as that in normal skin and at 98 days was also markedly higher than that in normal skin (P<0.05). Conclusion　Excessive deposition of collagen is a characteristic of hypertrophic scar in rabbits. The conversion of normal scarring to hypertrophic scarring in rabbits occurs at 14～21 days after operation. Both development and regression of hypertrophic scar in rabbit are quicker than that in human.

BACKGROUNDThe pathogenesis of hypersplenism and the immune function of the spleen in patients with portal hypertension (PH) remain obscure. This study aimed to evaluate the morphological changes of blood spleen barrier in spleen with hypersplenism due to PH and provide evidence for an in-depth investigation of the immune function of the spleen with hypersplenism and the mechanism of hypersplenism.

METHODSSpleen samples from 12 portal hypertensive patients and 4 patients with traumatic ruptures of spleen were examined. The samples of spleen were made into pathological sections, stained with Masson trichrome stain, Gomori stain, and CD68, CD34 immunohistochemistry, and were examined microscopically for the changes in the distribution of collagen fibers, reticular fibers, macrophages, and vascular endothelial cells. The changes in ultrastructure of macrophages and endothelial cells in marginal zone were also evaluated by transmission electron microscopy.

RESULTSAs compared to the normal spleen, the density of macrophage in the PH spleen was decreased, but the macrophages were mainly located in the marginal zone and distributed around the splenic corpuscle, with many villi and pseudopodium-like protrusion on the cell surface. The accrementition of collagen fibers was obvious around the splenic corpuscle and central artery. The increased reticulate fibers encircled the splenic corpuscle with more connection between the fibers. The vascular endothelial cells were in diffused distribution, without any regionality in PH spleen, but the vessel with enlarged lumina increased in red pulp.

CONCLUSIONSThe morphological changes of the blood spleen barrier can be one of the pathological fundaments for the abnormality of the immune function and the increased destruction of blood cells located in the spleens of patients with PH. However, this still entails clarification.

Adult ; Collagen ; analysis ; Endothelial Cells ; pathology ; ultrastructure ; Female ; Humans ; Hypertension, Portal ; immunology ; pathology ; Macrophages ; pathology ; ultrastructure ; Male ; Microscopy, Electron ; Middle Aged ; Spleen ; blood supply ; immunology ; pathology ; ultrastructure

Objective To investigate the relationship between single nucleotide polymorphisms of tumor suppressor gene PTEN and nasopharyngeal carcinoma in Jiamusi Han population. Methods The blood samples of 132 patients with naso-pharyngeal carcinoma(nasopharyngeal carcinoma group)and 73 healthy people(control group)were selected from September 2008 to January 2018 in the First Affiliated Hospital of Jiamusi University. The whole genome DNA was extracted,and the pol-ymorphisms of rs532678 and rs701848 were detected by restriction fragment length polymorphism analysis. The relationship be-tween the polymorphism of PTEN gene and nasopharyngeal carcinoma was analyzed. Results The genotype and allele frequen-cy distributions of rs532678 and rs701848 loci were in line with the Hardy-Weinberg genetic balance law in the two groups (P > 0. 05). The genotypic frequency of CC,CT and TT at the rs532678 locus of PTEN gene in the control group was 0. 630, 0. 342 and 0. 027 respectively;and the allele frequency of C and T was 0. 801 and 0. 198 respectively. The genotypic frequency of CC,CT and TT at the rs532678 locus of PTEN gene in the nasopharyngeal carcinoma group was 0. 716,0. 265 and 0. 015 re-spectively;and the allele frequency of C and T was 0. 852 and 0. 147 respectively. There was no significant difference in geno-type distribution and allele frequency distribution at the rs532678 locus of PTEN gene between the two groups(P > 0. 05). The genotypic frequency of CC,CT and TT at the rs701848 locus of the PTEN gene in the control group was 0. 657,0. 342 and 0. 000 respectively;and the allele frequency of C and T was 0. 828 and 0. 171 respectively. The genotypic frequency of CC,CT and TT at the rs701848 locus of PTEN gene in the nasopharyngeal carcinoma group was 0. 424,0. 500 and 0. 075 respectively;and the allele frequency of C and T was 0. 674 and 0. 325 respectively. The frequencies of CT,TT genotype and T allele of rs701848 locus in the nasopharyngeal carcinoma group were significantly higher than those in the control group(P < 0. 05). The frequencies of CC genotype and C allele in the nasopharyngeal carcinoma group were significantly lower than those in the control group(P < 0. 05). The individual with CT + TT genotype at the rs701848 locus of PTEN gene had higher risk for naso-pharyngeal carcinoma(P < 0. 05,OR = 2. 606,95％ confidence interval:1. 439 - 4. 720). The risk for nasopharyngeal carcino-ma in the individual with CT + TT genotype was 2. 606 times as much as the individual carrying CC genotype. Conclusion The rs532678 polymorphism of PTEN gene is not associated with the susceptibility to nasopharyngeal carcinoma. The polymor-phism of rs701848 locus is associated with the susceptibility to nasopharyngeal carcinoma. The individual carrying CT + TT genotype has higher risk for nasopharyngeal carcinoma.

OBJECTIVE: To study the clinical features of coronavirus disease 2019 (COVID-19) in children aged <18 years. METHODS: A retrospective analysis was performed from the medical data of 23 children, aged from 3 months to 17 years and 8 months, who were diagnosed with COVID-19 in Jiangxi, China from January 21 to February 29, 2020. RESULTS: Of the 23 children with COVID-19, 17 had family aggregation. Three children (13%) had asymptomatic infection, 6 (26%) had mild type, and 14 (61%) had common type. Among these 23 children, 16 (70%) had fever, 11 (48%) had cough, 8 (35%) had fever and cough, and 8 (35%) had wet rales in the lungs. The period from disease onset or the first nucleic acid-positive detection of SARS-CoV-2 to the virus nucleic acid negative conversion was 6-24 days (median 12 days). Of the 23 children, 3 had a reduction in total leukocyte count, 2 had a reduction in lymphocytes, 2 had an increase in C-reactive protein, and 2 had an increase in D-dimer. Abnormal pulmonary CT findings were observed in 12 children, among whom 9 had patchy ground-glass opacities in both lungs. All 23 children received antiviral therapy and were recovered. CONCLUSIONS COVID-19 in children aged <18 years often occurs with family aggregation, with no specific clinical manifestation and laboratory examination results. Most of these children have mild symptoms and a good prognosis. Epidemiological history is of particular importance in the diagnosis of COVID-19 in children aged <18 years.
Adolescent ; Betacoronavirus ; Child ; Child, Preschool ; China ; Coronavirus Infections ; Humans ; Infant ; Pandemics ; Pneumonia, Viral ; Retrospective Studies

Epithelial cell adhesion molecule (EpCAM) is a popular target for cancer therapy. In this research, 3 nanobodies with high specificity and endocytosis activity against EpCAM were developed, which provides a basis for the study of immunotoxin based on EpCAM. In our preliminary experiments, we have immunized a camel with EpCAM-Fc antigen and constructed a high-quality phage display library. Seventeen nanobodies with different complementarity determining region (CDR) 3 sequences have been screened after 3 rounds of biopanning by phage display technology. The animal procedures were approved by the Institutional Animal Care and Use Committee (IACUC) of Fudan University School of Pharmacy. After purification, 7 nanobodies showed high cell binding activity by fluorescent activated cell sorting (FACS) identification. Furthermore, 3 nanobodies presented high endocytosis activity based on FACS and laser confocal microscopy, which also showed high affinity to EpCAM measured by ForteBio. According to this study, we aimed to provide a novel alternative approach to the EpCAM-targeted therapy and to provide guidance for the study of nanobody based immunotoxins for other targets.

In the central nervous system, hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are essential to maintain normal neuronal function. Recent studies have shown that HCN channels may be involved in the pathological process of ischemic brain injury, but the mechanisms remain unclear. Autophagy is activated in cerebral ischemia, but its role in cell death/survival remains controversial. In this study, our results showed that the HCN channel blocker ZD7288 remarkably decreased the percentage of apoptotic neurons and corrected the excessive autophagy induced by oxygen-glucose deprivation followed by reperfusion (OGD/R) in hippocampal HT22 neurons. Furthermore, in the OGD/R group, p-mTOR, p-ULK1 (Ser), and p62 were significantly decreased, while p-ULK1 (Ser), atg5, and beclin1 were remarkably increased. ZD7288 did not change the expression of p-ULK1 (Ser), ULK1 (Ser), p62, Beclin1, and atg5, which are involved in regulating autophagosome formation. Besides, we found that OGD/R induced a significant increase in Cathepsin D expression, but not LAMP-1. Treatment with ZD7288 at 10 μmol/L in the OGD/R group did not change the expression of cathepsin D and LAMP-1. However, chloroquine (CQ), which decreases autophagosome-lysosome fusion, eliminated the correction of excessive autophagy and neuroprotection by ZD7288. Besides, shRNA knockdown of HCN2 channels significantly reduced the accumulation of LC3-II and increased neuron survival in the OGD/R and transient global cerebral ischemia (TGCI) models, and CQ also eliminated the effects of HCN2-shRNA. Furthermore, we found that the percentage of LC3-positive puncta that co-localized with LAMP-1-positive lysosomes decreased in Con-shRNA-transfected HT22 neurons exposed to OGD/R or CQ. In HCN2-shRNA-transfected HT22 neurons, the percentage of LC3-positive puncta that co-localized with LAMP-1-positive lysosomes increased under OGD/R; however, the percentage was significantly decreased by the addition of CQ to HCN2-shRNA-transfected HT22 neurons. The present results demonstrated that blockade of HCN2 channels provides neuroprotection against OGD/R and TGCI by accelerating autophagic degradation attributable to the promotion of autophagosome and lysosome fusion.