Cytocompatibility with osteogenic cells and enhanced in vivo anti-infection potential of quaternized chitosan-loaded titania nanotubes

Infection is one of the major causes of failure of orthopedic implants. Our previous study demonstrated that nanotube modification of the implant surface, together with nanotubes loaded with quaternized chitosan （hydroxypropyltrimethyl ammonium chloride chitosan, HACC）, could effectively inhibit bacterial adherence and biofilm formation in vitro. Therefore, the aim of this study was to further investigate the in vitro cytocompatibility with osteogenic cells and the in vivo anti-infection activity of titanium implants with HACC-loaded nanotubes （NT-H）. The titanium implant （Ti）, nanotubes without polymer loading （NT）, and nanotubes loaded with chitosan （NT-C） were fabricated and served as controls. Firstly, we evaluated the cytocompatibility of these specimens with human bone marrow-derived mesenchymal stem cells in vitro. The observation of cell attachment, proliferation, spreading, and viability in vitro showed that NT-H has improved osteogenic activity compared with Ti and NT-C. A prophylaxis rat model with implantation in the femoral medullary cavity and inoculation with methiciUin-resistant Staphylococcus aureus was established and evaluated by radiographical, microbiological, and histopathological assessments. Our in vivo study demonstrated that NT-H coatings exhibited significant anti-infection capability compared with the Ti and NT-C groups. In conclusion, HACC-loaded nanotubes fabricated on a titanium substrate show good compatibility with osteogenic cells and enhanced anti-infection ability in vivo, providing a good foundation for clinical application to combat orthopedic implant-associated infections.

The therapeutic potential of mesenchymal stem cells in Alzheimer's disease:converging mechanisms

Mesenchymal stem cells （MSCS） are pluripotent stem cells isolated from various tissues, but mostly from bone marrow, adipose tissue, and umbilical cord blood. Well known for their mesenchymal lineages differentiation （e.g., bone, cartilage and fat tissues）, it was suggested that MSCs possess plasticity prop- erties enabling them to differentiate into non-mesenchymal lineages. Indeed, several protocols claimed for differentiating MSCs to neurons in vitro, but concern was raised for the ef- fectiveness and in vivo relevance of such differentiation. Thus, though their neurogenic differentiation properties are still in debate, they were nevertheless, suggested as candidates for treat- ing neurodegenerative disorders such as Parkinson＇s diseases, multiple sclerosis and Alzheimer＇s disease （AD）.

Interventional effect of phycocyanin on mitochondrial membrane potential and activity of PC12 cells after hypoxia/reoxygenation

BACKGROUND： Phycocyanin can relieve decrease of mitochondrial membrane potential through reducing production of active oxygen so as to protect neurons after hypoxia/reoxygenation. OBJECTIVE： To observe the effect of phycocyanin on activity of PC12 cells and mitochondrial membrane potential after hypoxia/reoxygenation. DESIGN： Randomized controlled study SETTING ： Cerebrovascular Disease Institute of Affiliated Hospital, Medical College of Qingdao University MATERIALS： The experiment was carried out at the Key Laboratory of Prevention and Cure for cerebropathia in Shandong Province from October to December 2005. PC12 cells, rat chromaffin tumor cells, were provided by Storage Center of Wuhan University; phycocyanin was provided by Ocean Institute of Academia Sinica; Thiazoyl blue tetrazolium bromide （MTT） and rhodamine 123 were purchased from Sigma Company, USA; RPMI-1640 medium, fetal bovine serum and equine serum were purchased from Gibco Company, USA. METHODS： ① Culture of PC12 cells： PC12 cells were put into RPMI-1640 medium which contained 100 g/L heat inactivation equine serum and 0.05 volume fraction of fetal bovine serum and incubated in CO2 incubator at 37℃. Number of cells was regulated to 4 × 10^5 L 1, and cells were inoculated at 96-well culture plate. The final volume was 100μL. ② Model establishing and grouping： Cultured PC12 cells were randomly divided into three groups： phycocyanin group, model control group and non-hypoxia group. At 24 hours before hypoxia, culture solution in phycocyanin group was added with phycocyanin so as to make sure the final concentration of 3 g/L , but cells in model control group did not add with phycocyanin. Cells in non-hypoxia group were also randomly divided into adding phycocyanin group （the final concentration of 3 g/L） and non-adding phycocyanin group. Cells in model control group and phycocyanin group were cultured with hypoxia for 1 hour and reoxygenation for 1, 2 and 3 hours; meanwhile, cells in non-hypoxia group were cultured with oxygen and were measured at 1 hour after hypoxia/reoxygenation. ③ Detecting items： At 1, 2 and 3 hours after reoxygenation, absorbance （A value） of PC12 cells was measured with MTT technique so as to observe activity and quantity of cells. Fluorescence intensity of PC12 cells marked by rhodamine 123 was measured with confocal microscope in order to observe changes of mitochondrial membrane potential. MAEN OUTCOME MEASURES： Comparisons between quantity and activity of PC12 cells and mitochondria membrane potential at 1, 2 and 3 hours after reoxygenation. RESULTS： ① Effect of phycocyanin on quantity and activity of PC12 cells： A value was 0.924±0.027 in adding phycocyanin group and 0.924±0.033 in non-adding phycocyanin group. A value was lower in model control group and phycocyanin group than that in non-hypoxia group at 1, 2 and 3 hours after reoxygenation （0.817±0.053, 0.838±0.037, 0.875±0.029; 0.842±0.029, 0.872±0.025, 0.906±0.023, P 〈 0.05）. A value was higher in phycocyanin group than that in model control group at 1, 2 and 3 after culture （P 〈 0.05）. With culture time being longer, A value was increased gradually in phycocyanin group and model control group after reoxygenation （P 〈 0.05）. ~ Effect of phycocyanin on mitochondrial membrane potential of PC12 cells： Fluorescence intensity was 2.967±0.253 in adding phycocyanin group and 2.962±0.294 in non-adding phycocyanin group. Fluorescence intensity was lower in model control group and phycocyanin group than that in non-hypoxia group at 1, 2 and 3 hours after hypoxia/reoxygenation （1.899±0.397, 2.119±0.414, 2.287±0.402; 2.191±0.377, 2.264±0.359, 2.436±0.471, P 〈 0.05）; but it was higher in phycocyanin group than that in model control group at 1, 2 and 3 after reoxygenation （P 〈 0.05）. With culture time being longer, fluorescence intensity was increased gradually in phycocyanin group and model control group after reoxygenation （P 〈 0.05）. CONCLUSION： Phycocyanin and reoxygenation can protect PC12 cells after hypoxia injury through increasing mitochondrial membrane potential and cellular activity, and the effect is improved gradually with prolonging time of reoxygenation.

Effect of infusion pressure during cataract surgery on ganglion cells measured using isolated-check visual evoked potential

AIM： To detect the relationship between infusion pressure and postoperative ganglion cells function.METHODS： This prospective observational cohort study included sixty-one eyes that underwent uncomplicated cataract surgery. Patients were divided into two groups according to infusion time（IT） recorded using surgery equipment [Group A： IT〉IT_（mean）（27 eyes）; Group B： IT

Glypican 4 down-regulation in pluripotent stem cells as a potential strategy to improve differentiation and to impair tumorigenicity of cell transplants

Recent advances in stem cell technologies have opened new avenues for the treatment of a number of diseases still lacking effective therapeutic options.Cell transplantation has emerged as among the most promising clinical intervention for disorders such as injuries,diabetes,liver diseases, neurodegeneration and heart failure （Lee et al., 2013; Forbes and Rosenthal, 2014; Tabar and Studer, 2014）.

Potential utility of aldose reductase-deficient Schwann cells IKARS1 for the study of axonal degeneration and regeneration

Diabetic peripheral neuropathy（DPN）is one of the most common and intractable complications of diabetes mellitus.Its irritating symptoms,such as paresthesia,hyperalgesia and allodynia,can be causes of insomnia and depression;whereas its progression to more advanced stages can result in serious consequences,such as lower limb amputations and lethal arrhythmias.

Thermodynamic Foundation for High Temperature Electrochemistry

Thermodynamic concepts required for the thermodynamic calculation of the potentials of electrodes for high temperature applications are briefly reviewed. A thermodynamic approach to the calculation of half cell potentials and the standard chemical potential of an electron at high temperatures which are related to the Standard Hydrogen Electrode(SHE) is discussed. As examples, an external Ag/AgCl reference electrode and a YSZ(Ag|O_2) pH sensor for high temperature applications are analyzed by using the thermodynamic approach to derive a high temperature pH measurement equation. The two electrodes are employed to measure high temperature pH and the measured pH was compared with the calculated pH by using a solution chemistry method. Concepts and principles for electrode kinetics are also briefly introduced and a modification to the Tafel equations is suggested.

Differential thymosin β10 expression levels and actin filament organization in tumor cell lines with different metastatic potential

Background To investigate the differential expression levels of thymosin β10 (Tβ10) and the corresponding changes of actin filament organization in human tumor cell lines with different metastatic potential.Methods Four groups of nine human tumor cell lines with different metastatic potential were analyzed for the amount of Tβ10 mRNAs by Northern blot and for their peptide expression levels by immunohistochemistry. The filamentous actin (F-actin) was observed by staining of TRITC-phalloidin to detect changes in actin organization.Results In comparison with non-/weakly metastatic counterparts, Tβ10 was upregulated in highly metastatic human lung cancer, malignant melanoma and breast cancer cell lines. Staining of TRITC-phalloidin revealed less actin bundles, a fuzzy network of shorter filaments and some F-actin aggregates in the highly metastatic tumor cells. Meanwhile, the actin filaments were robust and orderly arranged in the non-/weakly metastatic cancer cell lines.Conclusion Tβ10 levels correlate positively with the metastatic capacity in human tumors currently examined. The increasing metastatic potential of tumor cells is accompanied by a loss of F-actin, poorly arranged actin skeleton organizations and presence of F-actin aggregates. There is a consistent correlation between the elevated Tβ10 expression and the disrupted actin skeleton.

Exploring the developmental potential of adult mammalian somatic cells

In the traditional views on developmental biology, the process of a mammal from a zygote to. an adult individual follows continuous changes of space and time environments and is the result of different expressions of target genes. It has long been known that this process is irreversible and the terminal differentiated adult cells, such as cardiac myocytes and neurons, will not divide and differentiate. But recent reports on the two hottest fields - cloning medicine and stem cell biology doubted these concepts. This may lead to a further understanding of the potentiality of mammal development and may provide great chances for commercial and clinical practice.

Calcium channels and their role in regenerative medicine

Stem cells hold indefinite self-renewable capability that can be differentiated into all desired cell types.Based on their plasticity potential,they are divided into totipotent(morula stage cells),pluripotent(embryonic stem cells),multipotent(hematopoietic stem cells,multipotent adult progenitor stem cells,and mesenchymal stem cells[MSCs]),and unipotent(progenitor cells that differentiate into a single lineage)cells.Though bone marrow is the primary source of multipotent stem cells in adults,other tissues such as adipose tissues,placenta,amniotic fluid,umbilical cord blood,periodontal ligament,and dental pulp also harbor stem cells that can be used for regenerative therapy.In addition,induced pluripotent stem cells also exhibit fundamental properties of self-renewal and differentiation into specialized cells,and thus could be another source for regenerative medicine.Several diseases including neurodegenerative diseases,cardiovascular diseases,autoimmune diseases,virus infection(also coronavirus disease 2019)have limited success with conventional medicine,and stem cell transplantation is assumed to be the best therapy to treat these disorders.Importantly,MSCs,are by far the best for regenerative medicine due to their limited immune modulation and adequate tissue repair.Moreover,MSCs have the potential to migrate towards the damaged area,which is regulated by various factors and signaling processes.Recent studies have shown that extracellular calcium(Ca^(2+))promotes the proliferation of MSCs,and thus can assist in transplantation therapy.Ca^(2+)signaling is a highly adaptable intracellular signal that contains several components such as cell-surface receptors,Ca^(2+)channels/pumps/exchangers,Ca^(2+)buffers,and Ca^(2+)sensors,which together are essential for the appropriate functioning of stem cells and thus modulate their proliferative and regenerative capacity,which will be discussed in this review.

PbS：Hg2＋ Nanostructures Films by Chemical Bath

The growth of nanocrystalline PbS films by chemical bath deposition （CBD） onto glass at temperatureT = 40 ± 2℃, is presented in this research. We report on the modification of structural, optical nanostructures due to in situ Hg-doping.The morphological changes of the layers were analyzed using AFM. XRD spectra displayed peaks at 20 = （26.00, 30.07, 43.10, 51.00, 53.48）, indicating growth on the zinc blende face. The grain size determined by x-rays diffraction of the undoped samples, was found -36 nm, whereas with the doped sample was 32-23 nm. Optical absorption, transition direct and indirect the forbidden band gap energy （Eg） shifts discloses a shift in the range 1.45-2.4 eV.

Return to the hematopoietic stem cell origin

Studying embryonic hematopoiesis is complicated by diversity of its locations in the constantly changing anatomy and by the mobility of blood cell precursors.Embryonic hematopoietic progenitors are identified in traditional in vivo and in vitro cell potential assays.Profound epigenetic plasticity of mammalian embryonic cells combined with significant inductive capacity of the potential assays suggest that our understanding of hematopoietic ontogenesis is substantially distorted.Non-invasive in vivo cell tracing methodology offers a better insight into complex processes of blood cell specification.In contrast to the widely accepted view based on the cell potential assays,the genetic tracing approach identified the yolk sac as the source of adult hematopoietic stem cell lineage.Realistic knowledge of the blood origin is critical for safe and efficient recapitulation of hematopoietic development in culture.

Effect of mitochondrial K_(ATP) channel on voltage gated K^+ channel in 24 hour-hypoxic human pulmonary artery smooth muscle cells

Background Hypoxic pulmonary hypertension (HPH) is initiated by inhibition of O 2 sensitive, voltage gated (Kv) channels in pulmonary arterial smooth muscle cells (PASMCs) The mechanism of hypoxic pulmonary hypertension has not yet been fully elucidated The mitochondrial ATP sensitive K + channel (MitoK ATP ) is extremely sensitive to hypoxia, and is a decisive factor in the control of mitochondrial membrane potential (ΔΨ m) This study investigated the changes of cell membrane potential and Kv channel in cultured human pulmonary artery smooth muscle cell (hPASMC) exposed to 24 hour hypoxia, and explored the role of MitoK ATP and ΔΨ m in this condition Methods Fresh human lung tissues were obtained from the patients undergoing a chest operation hPASMCs were isolated, cultured, and divided into 6 groups: ① control group, cultured under normoxia; ② diazoxide group, cultured in normoxia with diazoxide, an opener of MitoK ATP ; ③ 5 HD group, cultured in normoxia with sodium 5 hydroxydecanoate (5 HD), an antagonist of MitoK ATP ; ④ 24 hour hypoxia group; ⑤ 24 hour hypoxia + diazoxide group; and ⑥ 24 hour hypoxia + 5HD group Whole cell patch clamp technique was used to trace the cell membrane K + currents The expressions of cell membrane Kv1 5 mRNA and protein were determined by RT PCR and Western blot technique, respectively The relative changes in mitochondrial potential were tested with rhodamine fluorescence (R 123) technique Results After exposure to diazoxide for 24 hours, the intensity of R 123 fluorescence in normoxic hPASMCs was significantly increased compared with control group ( P <0 05), but there were no significant changes in these tests after the hPASMCs had been exposed to 5 HD for 24 hours Twenty four hour hypoxia or 24 hour hypoxia + diazoxide could markedly increase the intensity of R 123 fluorescence in hPASMC and the changes were more significant in 24 hour hypoxia +diazoxide group than in 24 hour hypoxia group ( P <0 05) although 5 HD could partly weaken the effect of 24 hour hypoxia on the intensity of R 123 fluorescence After exposure to diazoxide for 24 hours, the cell membrane K + currents and the expression of cell membrane Kv1 5 mRNA and protein in normoxic hPASMCs were significantly decreased compared with control group ( P <0 05), but there were no significant changes in these tests after the hPASMCs had been exposed to 5 HD for 24 hours Also, 24 hour hypoxia or 24 hour hypoxia + diazoxide decreased the cell membrane K + currents and the expression of Kv1 5 mRNA and protein ( P <0 05) but the changes were more significant in 24 hour hypoxia + diazoxide group than in 24 hour hypoxia group ( P <0 05) Again, 5 HD could partly weaken the inhibitory effect of 24 hour hypoxia on the cell membrane K + currents and the expression of Kv1 5 mRNA or protein ( P <0 05) Conclusions The opening of MitoK ATP followed by a depolarization of ΔΨ m in hypoxia might contribute to the alterations in the expression of cell membrane Kv1 5 mRNA and protein leading to change in the cell membrane potential of hypoxic hPASMCs This might be a mechanism of the development of hypoxic pulmonary hypertension

Changes in delayed rectifier K^+ channel function and its regulation by protein kinase C pathway in bronchial myocytes from asthmatic rats

Objective To investigate changes in the delayed rectifier K + channel (Kv) function and the regulation of Kv by the protein kinase C (PKC) pathway in bronchial myocytes from asthmatic rats. Methods The Kv currents and membrane potentials in bronchial myocytes from asthmatic rats and from controls were observed, using whole cell voltage- and current-patch clamp techniques.Results Bronchial myocytes from asthmatic rats showed a significant reduction in Kv-current density (51.6±9.4 pA/pF, n=14, P<0.01) in comparison with those from control rats (72.4±12.3 pA/pF, n=14) at +50 mV. The current-voltage relationship curve exhibited a significant downward shift. Bronchial myocytes from asthmatic rats had no significantly different capacitances (P>0.05), but had more positive membrane potential ( P<0.01) compared with those from controls. 1 μmol/L phorbol 12-myristate 13-acetate, a PKC activator, caused an obvious reduction in Kv-current density (P<0.01) and a significant downward shift in the current-voltage relationship curve, an effect which was partly abolished by 1 μmol/L Ro31-8220 (a PKC inhibitor); 1 μmol/L phorbol 12-myristate 13-acetate caused more positive membrane potential (Em), from -36.8±5.7 mV to -30.4±7.3 mV, in rat bronchial myocytes (P<0.05). This effect was partly abolished by 1 μmol/L Ro31-8220. Conclusions Bronchial myocytes from asthmatic rats have inhibited Kv function, more positive membrane potential, and higher excitability, all of which can also be induced by PKC activation. These characteristics may contribute to the development of airway hyperreactivity in asthma.