Objective To study the mechanism of arachnoidal fibrosis after subarachnoid hemor- rhage. Methods Rats were divided into control group, experiment group and treatment group. Radioim- munoassay (RIA) was employed to detect the levels of hyaluronic acid, laminin,type Ⅲ precollagen and type Ⅳ collagen in the arachnoid membrane. In the meantime, arachnoid cell's morphology and collagen distribution in the subarachnoid space were investigated by electron microscope. Results Results of RIA detection showed increase of Type Ⅲ precollagen level (peak at the second week), obvious higher levels of LN and HA but insignificant change of type IV collagen after subarachnoid hemorrhage. However, dexam- ethasone treatment decreased type Ⅲ precollagen level. Electron microscope found that arachnoid cells pres- ented accentruated bioactivity after subarachnoid hemorrhage, with significant increase of arachnoidal colla- gen fibers from one week after suharachnoid hemorrhage, continuing for 3 weeks. Dexamethasone treatment resulted in low density of mitochondria and sparsed arachnoidal collagen fibers. Conclusions Extracellu- lar matrix (ECM) increases in arachnoid membrane after subarachnoid hemorrhage and participates in a- rachnoid fibrosis. Dexamethasoue can relieve arachnoidal fibrosis after subarachnoid hemorrhage, as pro- rides fresh way for prevention and treatment of post hemorrhagic hydrocephalus.

Objective To investigate the influence of physiological motions on three-dimensional (3D) CT images and the rules of motion artifacts.Methods A mathematical model of motion artifact was set up based on the principle of spiral scanning, hereby the geometrical distortion of 3D image was analyzed.Experiments were carried out with home-made phantoms on a CT scanner.Results The details of 3D images with trivial distortion were legible under static condition.On the contrary, distinct distortion occured under moving condition, and its degree increased with the pitch and motion period. The 3D images were varied with difference of the motion initial phases.Conclusion The distortion of 3D-CT image depends on the motion characters of scanned objects and scanning parameters such as pitch and slice thickness.

The TLD(thermoluminescent dosimetry)must be calibrated before used in individual dosimetry.In this paper,some related issues that affect the accuracy of calibration,including principle and performance of the instruments,conditions of annealing and measuring,method of curve fitting are discussed and an appropriate calibration method is proposed.The results show that the method we proposed is valid and efficient,which ensures the accuracy of individual dosimetry.

Objective To explore the changes in plasma nitric oxide (NO) and nitric oxide synthase (NOS) activity in children with orthostatic hypertension(OHT) and the relationship with blood pressure changes.Methods The OHT group included 51 children who were diagnosed OHT in in-patient and out-patient departments of Peking University First Hospital from Jun.2012 to Jun.2013.Their age range was (12 ± 2) years.At the same time,control group consisted of 28 normal children who received physical examination with their age range of(12 ± 1) years.The diagnosis of OHT was based on the clinical manifestation and head-up tests.Plasma NO was determined by using a nitrate reductase method and plasma NOS activity by a chemical colorimetric method.Results 1.There were no significant differences between OHT group and control group in age,sex ratio,height,weight and body mass index (all P ＞0.05).2.In OHT children,the upright systolic blood pressure was higher than that of the supine [(114 ± 10) mmHg vs (104 ± 9) mmHg,t =-12.853,P ＜ 0.001],and the upright diastolic blood pressure was higher than that of the supine[(73 ±7) mmHg vs(59 ± 8) mmHg,t =-21.859,P ＜0.001].3.Plasma NO level and NOS activity,however,were significantly lower in OHT group than those in the control group [NO:(28.947 ± 6.031) μmol/L vs (35.216 ±6.662) μmol/L,t =4.257,P ＜ 0.001 ; NOS activity:(14.753 ± 3.060) U/mL vs (17.560 ± 4.253) U/mL,t =3.026,P =0.006].4.There was significantly negative correlation between plasma NO and the upright systolic blood pressure(r =-0.276,P ＜ 0.05) and the systolic blood pressure change (r =-0.280,P ＜ 0.05).Conclusions Plasma NO level and NOS activity were significantly lower in OHT children than those in control group.The abnormal vascular endothelial function may play an important role in OHT in children.

Although methyltransferase has been recognized as a major element that governs the epigenetic regulation of the genome during temozolomide (TMZ) chemotherapy in glioblastoma multiforme (GBM) patients, its regulatory effect on glioblastoma chemoresistance has not been well defined. This study investigated whether DNA methyltransferase (DNMT) expression was associated with TMZ sensitivity in glioma cells and elucidated the underlying mechanism. DNMT expression was analyzed by western blotting. miR-20a promoter methylation was evaluated by methylation-specific PCR. Cell viability and apoptosis were assessed using the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) and TdT-mediated dUTP-biotin nick end labeling assays, respectively. The results showed that compared with parental U251 cells, DNMT1 expression was downregulated, miR-20a promoter methylation was attenuated and miR-20a levels were elevated in TMZ-resistant U251 cells. Methyltransferase inhibition by 5-aza-2\'-deoxycytidine treatment reduced TMZ sensitivity in U251 cells. In U251/TM cells, DNMT1 expression was negatively correlated with miR-20a expression and positively correlated with TMZ sensitivity and leucine-rich repeats and immunoglobulin-like domains 1 expression; these effects were reversed by changes in miR-20a expression. DNMT1 overexpression induced an increase in U251/TM cell apoptosis that was inhibited by the miR-20a mimic, whereas DNMT1 silencing attenuated U251/TM cell apoptosis in a manner that was abrogated by miR-20a inhibitor treatment. Tumor growth of the U251/TM xenograft was inhibited by pcDNA-DNMT1 pretreatment and boosted by DNMT1-small hairpin RNA pretreatment. In summary, DNMT1 mediated chemosensitivity by reducing methylation of the microRNA-20a promoter in glioma cells.
Animals ; Antineoplastic Agents, Alkylating/*pharmacology/therapeutic use ; Apoptosis/drug effects ; Brain/drug effects/metabolism/pathology ; Brain Neoplasms/drug therapy/*genetics/pathology ; DNA (Cytosine-5-)-Methyltransferase/antagonists & inhibitors/*genetics/metabolism ; DNA Methylation ; Dacarbazine/*analogs & derivatives/pharmacology/therapeutic use ; Drug Resistance, Neoplasm ; Female ; Gene Expression Regulation, Neoplastic ; Glioma/drug therapy/*genetics/pathology ; Humans ; Mice, Inbred C57BL ; MicroRNAs/*genetics ; Promoter Regions, Genetic

BACKGROUNDThe abnormal blood volume regulation is one of the most important pathogenesis in postural tachycardia syndrome in children. This study was designed to investigate the plasma atrial natriuretic peptide and antidiuretic hormone levels in postural tachycardia syndrome children, and their associations with the changes in heart rate and blood pressure in head-up test.

METHODSTwenty-one postural tachycardia syndrome patients ((12 ± 2) years) and 26 healthy children ((12 ± 1) years) were included. According to blood pressure changes in head-up test, the postural tachycardia syndrome patients were divided into two subgroups: postural tachycardia syndrome with orthostatic hypertension and postural tachycardia syndrome without orthostatic hypertension. The plasma atrial natriuretic peptide and antidiuretic hormone levels were measured using enzyme-linked immunosorbent assay.

RESULTSThe plasma atrial natriuretic peptide level in postural tachycardia syndrome patients was higher than the control (P = 0.004), whereas the difference in plasma antidiuretic hormone level between postural tachycardia syndrome and controls was not significant (P = 0.222). The plasma antidiuretic hormone level of patients suffering from postural tachycardia syndrome with orthostatic hypertension was much higher than that of children having postural tachycardia syndrome without orthostatic hypertension (P < 0.05). In postural tachycardia syndrome patients, the upright max heart rate was positively correlated with the plasma atrial natriuretic peptide level (r = 0.490, P < 0.05) and the upright systolic blood pressure was positively correlated with the plasma antidiuretic hormone levels (r = 0.472, P < 0.05).

CONCLUSIONSThere was a disturbance of plasma atrial natriuretic peptide and antidiuretic hormone in postural tachycardia syndrome children.

Adolescent ; Atrial Natriuretic Factor ; blood ; Case-Control Studies ; Child ; Humans ; Hypertension ; blood ; Postural Orthostatic Tachycardia Syndrome ; blood ; Vasopressins ; blood