The aim of this study was to obtain the alginate gels which could have proper compressive strength and excellent permeability for cell proliferation and could have more promising potentials in the application of tissue engineering. Through the reaction of the carboxyl of the alginate and the amino of methacrylic acid, methylacrylic was generated into alginate long chain which could be enhanced by the polymerization of double bond under thermal reaction condition. And then alginate gel beads were prepared using the mixture of calcium chloride and barium chloride solution as cationic crosslinker, and the compressive modulus and permeability of the prepared alginate gel beads were investigated. When the ratio of barium ions to calcium ions was 5:5, the compression modulus was 189.7 kPa, and it showed the best permeability for trypsin with molecular weight of 24 kDa and entrapment effect for bovine serum albumin with molecular weight of 67 kDa. Compared to compositions of other ratios, the alginate gel beads made in 5:5 mixture indicated excellent compressive modulus and permeability. These results indicated that the alginate hydrogel beads with the ratio of barium ions to calcium ions being 5:5 have a potential application in tissue engineering as a support material and encapsulating materials in cell culture.
Alginates ; chemistry ; Barium Compounds ; chemistry ; Calcium Chloride ; chemistry ; Cations ; Cell Culture Techniques ; Cell Proliferation ; Chlorides ; chemistry ; Cross-Linking Reagents ; chemistry ; Gels ; chemistry ; Metals ; Polymethacrylic Acids ; chemistry ; Tissue Engineering

BACKGROUND: Angiotensin Ⅱ (Ang Ⅱ) can induce cardiac hypertrophy and platelet-derived growth factor(PDGF) also stimulates cardiac hypertrophy. Is AngⅡ responsible for the pathogenesis of cardiac hypertrophy by inducing PDGF receptor expression?OBJECTIVE: To investigate the effect of mitogen activated protein kinase (MAPK) on the role of cardiac hypertrophy induced by Ang Ⅱ in cardiac myocytes so as to provide theoretical basis for clinical prevention and cure of cardiac hypertrophy.DESIGN: Controlled experimental study taking cardiac myocytes of cultured neonatal rats as subjects.SETTING: Department of pathophysiology in a university.MATERIALS: The experiment was completed in the Department of Pathophysiology, Medical College of Peking University. A total of 80 Wistar rats of either gender, aged 1 - 3 days, were provided by the Animal Center of Medical College, Peking University. Their hearts were removed for myocyte culture in the Cell Culture Laboratory.INTERVENTIONS: The cultured neonatal rat cardiac myocytes treated with 10-7mol/L Ang Ⅱ were Ang Ⅱ group, and those preincubated with 10-5mol/L PD98059(an antagonist of MAPK) for 30 minutes and then treated with Ang Ⅱ were PD98059 group. Cardiac myocytes of normal neonatal rats were as control group. The expression of PDGF-β was detected by western blot at 24 hours.MAIN OUTCOME MEASURES: Content of PDGF-β receptor in neonatal rat cardiac myocytes.RESULTS: The expression of PDGF-β receptor induced by Ang Ⅱ at neonatal rat cardiac myocytes markedly increased at 24 hours (432.41 ± 54.08) compared with that of control group(197.65 ± 44. 10) ( q = 6.77, P< 0.01 ). PDGF-β receptor expression of PD98059 group(317.2 ± 21.12) decreased compared with that of Ang Ⅱ group(q = 3.91, P < 0.05) .However, the expression did not return to the level of control group, and there was significant difference between PD98059 group and control group( q= 3.85, P <0.05).CONCLUSION: The results indicate that angiotensin Ⅱ promotes cardiac hypertrophy through inducing expression of PDGF receptor, in which mitogen activated protein kinase participates in. Maybe it is another important mechanism for Ang Ⅱ -induced cardiac hypertrophy. The results can provide experimental data for the primary and secondary prevention in heart rehabilitation.

This study was to explore a better three-dimensional (3-D) culture method of chondrocyte. The interpenetrating network (IPN) gel beads were developed through a photo-cross linking reaction with mixed barium ions and calcium ions at the ratio of 5:5 with the methacrylic alginate (MA), which was a chemically conjugated alginate with methacrylic groups. The second generation of primary cartilage cells was encapsulated in the MA gel beads for three weeks. In the designated timing, HE stain, Alamar blue method and Scanning electron microscopic were used to determine the cartilage cells growth, proliferation and the cell distribution in the scaffolds, respectively. The expression of type II collagen was investigated by an immunohistochemistry assay and the glycosaminoglycan content was quantitatively evaluated with the spectrophotometry of 1, 9 dimethylene blue assay. Compared to the alginate control group, the deposition of glycosaminoglycan was significantly upregulated in IPN-MA gel beads with higher cell proliferation. The secretion of extracellular matrix and proliferation of chondrocyte in methacrylic alginate gel beads were higher than that in Alginate beads. Cells were able to attach, to grow well on the scaffolds under scanning electron microscopy. The result of immunohistochemistry staining of collagen type II was positive, confirming the maintenance of chondrocyte phenotype in methacrylic alginate gel beads. This study shows a great potential for three-dimensional culture of cartilage.
Alginates ; chemistry ; Barium ; chemistry ; Calcium ; chemistry ; Cartilage ; cytology ; Cations ; Cell Culture Techniques ; instrumentation ; Cells, Cultured ; Chondrocytes ; cytology ; Collagen Type II ; chemistry ; Glucuronic Acid ; chemistry ; Glycosaminoglycans ; chemistry ; Hexuronic Acids ; chemistry ; Metals ; chemistry ; Microscopy, Electron, Scanning

Objective To study the effect of community health education on lactation mastitis and breast feeding.Method Ninety parturients were given community health education for 6 months and then the rates of mastitis and breast feeding were recorded.Results The mastitis morbidity was 3.3%and the rate of breast feeding was 97.8%.Conclusion The implementation of the community health education can reduce the morbidity of maternal mastitis and raise the rate of breast feeding.

AIM: To investigate the crosstalk between angiotensin Ⅱ (AngⅡ)-mediated and platelet-derived growth factor (PDGF)-mediated signal transduction in vascular smooth muscle proliferation.METHODS: A model of renal hypertension was made by two kidney/one-clip operation. Level of PDGF receptor β subunit of aorta was measured by Western Blot analysis. The effect of Ang Ⅱ on PDGF receptor β subunit expression was investigated in culture rat aortic vascular smooth muscle cells (VSMC).RESULTS: Systolic blood pressure obviously increased at 8th week after operation, whereas the level of PDGF receptor β subunit of aorta significantly increased by 126.6% (P＜0.05) in 2K1C rats compared with control group. The expression of PDGF receptor β subunit in cultured VSMC stimulated by AngⅡ was higher than that of control by 192.74%(P＜0.01). The effect of AngⅡ was inhibited remarkably by pretreated with losartan, a kind of specific AngⅡ receptor 1 (AT1) subtype antagonist and U73122, a kind of phospholipase C inhibitor. The effect was partly blocked by PD98059, which inhibit the activity of mitogen-activated, ERK-activating kinase (MEK).CONCLUSION: AngⅡ-induced PDGF receptor β subunit expression is regulated by the AT1 and its downstream signal molecule-PLC and ERK, might participate in the intracellular signal transduction pathway.

Objective To investigate the occupational value status of pediatric nurses in level two hospitals, so as to provide evidence for nursing human resource management. Methods From March to April 2013, convenient sampling method was used to select 150 pediatric nurses in 4 level two hospitals who were investigated by occupational value scale. Results The total score of occupational value among pediatric nurses was (4. 38 ± 0. 46), in which care dimension acquired the highest score (4. 46 ± 0. 46) while behavior dimension obtained the lowest score (4. 21 ± 0. 64). Multiple regression analysis presented that occupational value total score of pediatric nurses was impacted by education background and working years. Conclusions Occupational value score of pediatric nurses in level two hospitals is above average level, so nursing managers can manage nursing human resources scientifically according to the recognition characteristics of occupational value in pediatric nurses.