Effects of Arg–Gly–Asp-modified elastin-like polypeptide on pseudoislet formation via up-regulation of cell adhesion molecules and extracellular matrix proteins

Extracellular matrix (ECM) plays an important role in controlling the β-cell morphology, survival and insulin secretary functions. An RGD-modified elastin-like polypeptide (RGD-ELP), TGPG[VGRGD(VGVPG)₆]₂₀WPC, has been reported previously as a bioactive matrix. In this study, to investigate whether RGD-ELP affects β-cell growth characteristics and insulin secretion, β-TC6 cells were cultured on the RGD-ELP coatings prepared via thermally induced phase transition. On RGD-ELP, β-TC6 cells clustered into an islet-like architecture with high cell viability. Throughout 7 days’ culture, the proliferation rate of the cells within a pseudoislet was similar to that of monolayer culture. Under high glucose (25 mM), β-TC6 pseudoislets showed up-regulated insulin gene expression and exhibited glucose-stimulated insulin secretion. Importantly, the mRNA and protein abundances of cell adhesion molecules (CAM) E-cadherin and connexin-36 were much higher in pseudoislets than in monolayer cells. The siRNA-mediated inhibition of E-cadherin or connexin-36 expression severely limited pseudoislet formation. In addition, the mRNA levels of collagen types I and IV, fibronectin and laminin were significantly elevated in pseudoislets. The results suggest that RGD-ELP promotes pseudoislet formation via up-regulation of the CAM and ECM components. The functional roles of RGD-ELP are discussed in respect of its molecular composition.     

A prospective,multicenter phase II study of continuous infusion of FLAG for patients older than 60 yr with resistant acute myeloid leukemia: a comparison with intensive younger patients’ trial

Relapsed or refractory acute myeloid leukemia (R/R AML) in elderly (≥60 yr old) patients were eligible. Induction chemotherapy consisted fludarabine and cytarabine (ARAC) as a 24‐hr CI without idarubicin (C‐FLAG), which was compared with the results of C‐FLAG with idarubicin (CI‐FLAG2) in younger patients’ trial. A total of 33 and 68 patients were enrolled in C‐FLAG and CI‐FLAG2, respectively. CR, CRp, and CRi were achieved in 10 (30.3%), 3 (9.1%), and 2 (6.1%), respectively. When comparing outcomes between C‐FLAG and CI‐FLAG2, there were no difference in terms of CR rate (P = 0.572) and objective response rate (ORR; P = 0.899). Favorable predictors on ORR in C‐FLAG were PB WBC ≤ 20K/uL at salvage (P = 0.024) and early evaluation peripheral BLAST = 0% (P = 0.013) on multivariate analysis. The overall survival of patients who achieve CR/CRp/CRi showed significantly prolonged survival compared with patients who did not in C‐FLAG (P < 0.001) and was a favorable predictor of longer survival by multivariate analysis (P = 0.009). Median overall survival was 3.19 (95% CI, 2.05–4.33) months and similar with that of CI‐FLAG2 (P = 0.841). Attenuated salvage regimen C‐FLGA in elderly patients was as effective as more intensive younger patients’ regimen CI‐FLAG2 in terms of response and survival although elderly patients had more unfavorable clinical characteristics.     

Selective bacterial patterning using the submerged properties of microbeads on agarose gel

We proposed a new bacteria patterning method on the restricted region of microbeads, using the submerged property of polystyrene microbeads on various concentrations of agarose gel. Moreover, we fabricated a bacterial microrobot using attenuated Salmonella typhimurium through the new patterning methods. We controlled the submerged degree of polystyrene microbeads through the regulation of the hardness of the agarose gel. The polystyrene microbeads on agarose gel were transferred onto a poly-dimethylsiloxane (PDMS) surface for easy manipulation of the microbeads. Then, we treated the polystyrene microbeads on the PDMS surface with antibacterial adherent factors, such as O₂ plasma and bovine serum albumin (BSA). The Salmonella typhimurium was attached to the entire surface of the untreated polystyrene microbeads, whereas Salmonella typhimurium were only attached to the restricted surface region of the treated polystyrene microbeads through the proposed patterning method. The bacteria-attached microbeads gain motility by the propulsion of the attached bacteria, and the selective-bacteria-attached microbeads showed enhanced motility. Compared with whole-bacteria-attached polystyrene microbeads (1.74?±?1.62 μm/s), the selective bacteria-attached polystyrene microbeads, using O₂ plasma and BSA, showed 9.18?±?1.88 μm/s and 14.65?±?8.66 μm/s faster moving velocities, respectively. Through the results, we expected that the proposed patterning methodology of microbeads could contribute to the development of biomedical bacterial microrobots.     

Acute Hypoxia Activates an ENaC-like Channel in Rat Pheochromocytoma (PC12) Cells

Cells can resist and even recover from stress induced by acute hypoxia, whereas chronic hypoxia often leads to irreversible damage and eventually death. Although little is known about the response(s) to acute hypoxia in neuronal cells, alterations in ion channel activity could be preferential. This study aimed to elucidate which channel type is involved in the response to acute hypoxia in rat pheochromocytomal (PC12) cells as a neuronal cell model. Using perfusing solution saturated with 95% N₂ and 5% CO₂, induction of cell hypoxia was confirmed based on increased intracellular Ca²⁺ with diminished oxygen content in the perfusate. During acute hypoxia, one channel type with a conductance of about 30 pS (2.5 pA at -80 mV) was activated within the first 2~3 min following onset of hypoxia and was long-lived for more than 300 ms with high open probability (P_o, up to 0.8). This channel was permeable to Na⁺ ions, but not to K⁺, Ca⁺, and Cl^- ions, and was sensitively blocked by amiloride (200 nM). These characteristics and behaviors were quite similar to those of epithelial sodium channel (ENaC). RT-PCR and Western blot analyses confirmed that ENaC channel was endogenously expressed in PC12 cells. Taken together, a 30-pS ENaC-like channel was activated in response to acute hypoxia in PC12 cells. This is the first evidence of an acute hypoxia-activated Na⁺ channel that can contribute to depolarization of the cell.