ROS Mediate xCT-Dependent Cell Death in Human Breast Cancer Cells under Glucose Deprivation.

xCT, also known as solute carrier family 7 member 11 (SLC7A11), the light chain of the cystine/glutamate antiporter, is positively correlated with cancer progression due to antioxidant function. During glucose deprivation, the overexpression of xCT does not protect cancer cells but instead promotes cell death. Further understanding the mechanism of glucose deprivation-induced cell death is important for developing anticancer treatments targeting the glucose metabolism. In this study, we found that breast cancer cells with a high expression of xCT demonstrated increased levels of reactive oxygen species (ROS) and were more sensitive to glucose deprivation than the cells with a low expression of xCT. However, AMP-activated protein kinase (AMPK) did not significantly affect glucose-deprivation-induced cell death. The antioxidant N-acetyl-cysteine prevented glucose-deprivation-induced cell death, and the glutathione biosynthesis inhibitor L-buthionine-S, R-sulfoximine enhanced glucose-deprivation-induced cell death. The inhibition of xCT by sulfasalazine or a knockdown of xCT reduced the glucose-deprivation-increased ROS levels and glucose-deprivation-induced cell death. Glucose deprivation reduced the intracellular glutamate, and supplementation with α-ketoglutarate prevented the glucose-deprivation-increased ROS levels and rescued cell death. The knockdown of sirtuin-3 (SIRT3) further enhanced the ROS levels, and promoted xCT-related cell death after glucose deprivation. In conclusion, our results suggested that ROS play a critical role in xCT-dependent cell death in breast cancer cells under glucose deprivation.

Albumin supplementation may have limited effects on prolonged hypoalbuminemia in major burn patients: An outcome and prognostic factor analysis.

BACKGROUND: Burns that affect ≥20% of the total body surface area (TBSA) trigger a major inflammatory response in addition to capillary leakage and loss of serum proteins including albumin. Persistent hypoalbuminemia is therefore common in major burn patients. The purpose of this study was to determine whether human albumin solutions can benefit major burn patients with persistent hypoalbuminemia. METHODS: We conducted a retrospective review of major burn patients with ≥20% of TBSA involved at Taipei Veterans General Hospital between January 2007 and December 2018. Thirty-eight patients were enrolled. Patient demographics, burn characteristics, fluid balance, laboratory results, and outcomes were recorded through chart review. RESULT: No significant differences were found in the baseline characteristics of patients who received <25 mg/kg/%TBSA/day of human albumin solutions and those who received more than this amount. Renal replacement therapy, duration of mechanical ventilation, length of stay in the burn unit, and in-hospital mortality rate were not statistically different between the two groups. The serum C-reactive protein/albumin ratio was associated with in-hospital mortality (p = 0.036). CONCLUSION: The administration of large amounts of albumin supplements for the correction of prolonged hypoalbuminemia in major burn patients had no significant benefits on mortality.

Illness representations and coping processes of Taiwanese patients with early-stage chronic kidney disease.

BACKGROUND: Chronic kidney disease (CKD) is a public health problem worldwide with an increasing incidence and prevalence and high cost. The role of illness perceptions in understanding health-related behavior has received little attention in patients with early-stage CKD. PURPOSE: This qualitative study aimed to describe the illness representation and coping process experience of patients with early-stage CKD in Taiwan. METHODS: A qualitative content analysis approach was used to analyze semistructured, open-ended, one-on-one interviews with 15 patients with early-stage CKD. Purposive sampling was used to recruit patients diagnosed with early-stage CKD from the nephrology departments of two medical centers in Taiwan. Trustworthiness of the study was evaluated using four criteria suggested by Lincoln and Guba. RESULTS: Six themes emerged from the analysis: experiencing early symptoms, self-interpreting the causes of having CKD, realizing CKD as a long-term disease, believing CKD could be controlled by following doctors' orders, anticipating the consequences of having CKD, and adopting coping strategies to delay the progress of CKD. CONCLUSIONS/IMPLICATIONS FOR PRACTICE: Findings from this study compared with previous studies reveal that education can effectively change patient illness representations as an approach to improve coping behavior. This finding offers healthcare professionals insight into the health education necessary to assess patient illness representation to provide culturally sensitive interventions.

Retinoic acid mediates the expression of glutamate transporter-1 in rat astrocytes through genomic RXR action and non-genomic protein kinase C signaling pathway.

Astrocytic glutamate transporter-1 (GLT-1) is responsible for 90% of forebrain glutamate uptake in the adult CNS. Retinoic acid (RA) is a potent regulator of neural cell differentiation and neuronal maturation in the developing CNS through activation of RA receptors/retinoic X receptors (RXRs) or non-genomic mechanisms. Although rat GLT-1 contains several RXR binding regions, RA-triggered RXR mechanisms regulating GLT-1 expression remain unknown. RA applied at submicromolar concentrations for 24 h significantly reduced GLT-1 mRNA and membrane levels in astrocytes and dibutyryl cAMP (dbcAMP)-primed astrocytes. An RXR agonist reduced astrocytic GLT-1 mRNA expression, whereas an RXR antagonist blocked the effects of RA on the reduction of astrocytic GLT-1 mRNA expression. Electrophoresis motility shift assay indicated that RA-treatment increased astrocytic RXR-DNA binding activity. RA-induced reduction in GLT-1 mRNA expression was also observed in dbcAMP-primed astrocytes. Through lentivirus-mediated astrocytic over-expression of rat GLT-1, levels of GLT-1 in the processes of dbcAMP-treated astrocytes were attenuated by exposure to RA. The protein kinase C inhibitor, Bis I, restored GLT-1 distribution in the processes of RA-treated dbcAMP-primed astrocytes. These results suggest that RA reduces astrocytic GLT-1 levels through both RXR-mediated inhibition at the transcriptional level and triggering activation of protein kinase C which reduces cell surface GLT-1 levels.

Sho-saiko-to (Xiao-Chai-Hu-Tang) and crude saikosaponins inhibit hepatitis B virus in a stable HBV-producing cell line.

To search for an effective antiviral agent, this study tested the hypothesis that sho-saiko-to (Xiao-Chai-Hu-Tang) and crude saikosaponins possess the activity directly against HBV and could affect the expressions of viral antigens, HBeAg and HBsAg, in HepG(2) 2.2.15 cell model. The viral amount and viral antigens in the suspension were estimated by quantitative real time PCR and enzyme-linked immunosorbent assay (ELISA), respectively. The results showed that sho-saiko-to could inhibit the production of HBV (p < 0.0001), 20 microg/ml sho-saiko-to was efficacious at day-3 of treatment and 10 microg/ml at day-6. The calculated IC(50) and CC(50) of sho-saiko-to were 55.76 microg/ml and 372 microg/ml, respectively, with a selectivity index of 6.67. Crude saponin of B. chinense could also inhibit the replication of HBV (p < 0.0001). Owing to the anti-neoplastic activity of sho-saiko-to and saikosaponin, their calculated CC(50) and selectivity index might be under-estimated. Sho-saiko-to also decreased the expression of HBeAg with the minimal effective concentration of 20 microg/ml. Sho-saiko-to contained too little saikosaponin. Therefore, the anti-HBV activity of sho-saiko-to might not be mediated by saikosaponin. Sho-saiko-to could be supplementary to nucleotide analogues to minimize the recurrence of viremia after its discontinuation.

Ethanol extract of Polygonum cuspidatum inhibits hepatitis B virus in a stable HBV-producing cell line.

Chronic hepatitis B virus (HBV) infection is endemic in Asia and its consequences are among the major public health problems in the world. Unfortunately, the therapeutic efficacies of present strategies are still unsatisfactory with a major concern about viral mutation. In search of effective antiviral agent, we examined the efficacy of extracts of Polygonum cuspidatum Sieb. et Zucc. (P. cuspidatum) against HBV in HepG2 2.2.15 cells by quantitative real time polymerase chain reaction. The expressions of viral antigens, HBeAg and HBsAg, were also determined by enzyme linked immunosorbent assay. The ethanol extract of P. cuspidatum could inhibit dose-dependently the production of HBV (p<0.0001) with an effective minimal dosage of 10 microg/ml. The water extract of P. cuspidatum might also inhibit the production of HBV at a higher dosage. The expression of HBsAg was significantly increased by both ethanol extract and water extract of P. cuspidatum dose-dependently (p<0.0001) and time-dependently (p<0.0001). Higher dose of water extract of P. cuspidatum (30 microg/ml) could inhibit the expression of HBeAg (p<0.05). The extract of P. cuspidatum might contain compounds that would contribute to the control of HBV infection in the future. However, its promoting effect on the expression of HBsAg and its cytotoxicity should be monitored. Further purification of the active compounds, identification and modification of their structures to improve the efficacy and decrease the cytotoxicity are required.

Suppressive effects of 3-O-methylquercetin on ovalbumin-induced airway hyperresponsiveness.

Rhamnus nakaharai Hayata (Rhamnaceae) has been used as a folk medicine in Taiwan for treating constipation, inflammation, tumors, and asthma. 3-O-Methylquercetin (3-MQ), a main constituent of the plant, has been reported to inhibit total cAMP- and cGMP-phosphodiesterase (PDE) of guinea pig trachealis at low concentrations. 3-MQ has been also reported to more selectively inhibit PDE3 than PDE4 with a low K(m) value. Therefore we were interested in investigating its suppressive effects on ovalbumin (OVA)-induced airway hyperresponsiveness in vivo and in vitro. 3-MQ (3-30 micromol/kg, i. p.) significantly suppressed the enhanced pause (Penh) value induced by aerosolized methacholine (50 mg/mL) in sensitized mice after secondary allergen challenge. 3-MQ (3-30 micromol/kg, i. p.) also significantly suppressed total inflammatory cells, macrophages, neutrophils, and eosinophils, but not lymphocytes. In addition, 3-MQ (3 micromol/kg, i. p.) significantly decreased the secretion of TNF-alpha, and at the highest dose (30 micromol/kg, i. p.) even decreased the secretions of IL-4, IL-5, and TNF-alpha. 3-MQ (1-10 microM) as well as Ro 20-1724 (3-30 microM), a selective PDE4 inhibitor, significantly attenuated OVA (100 microg/mL)-induced contractions. 3-MQ (30 microM) as well as milrinone (1-10 microM), a selective PDE3 inhibitor, significantly enhanced baseline contractions in isolated guinea pig left and right atria. However, neither 3-MQ nor milrinone significantly affected baseline beating rate in the right atria. 3-MQ (3-30 micromol/kg, i. p.) did not significantly affect systolic pressure in conscious mice. In conclusion, 3-MQ has both anti-inflammatory and bronchodilating effects, and has the potential for use in the treatment of asthma at a dose without affecting blood pressure.

3-O-methylquercetin more selectively inhibits phosphodiesterase subtype 3.

Rhamnus nakaharai Hayata (Rhamnaceae), has been used as a folk medicine in Taiwan for treating constipation, inflammation, tumors and asthma. 3-O-methylquercetin (3-MQ), a main constituent of the plant, has been reported to inhibit total cAMP- and cGMP-phosphodiesterase (PDE) of guinea pig trachealis. Therefore we were interested in investigating the inhibitory effect of 3-MQ on various PDE isozymes from guinea pig lungs and hearts. Isolated guinea pig lungs and hearts were homogenized and centrifuged. The supernatant was chromatographed over a column of Q-sepharose, and eluted with various concentrations of NaCl. In the following order, PDE subtypes 1, 5, 2, 4 from lungs, and 3 from hearts were separated. The IC 50 values of 3-MQ on these isozymes were 31.9, 86.9, 18.6, 28.5 and 1.6 microM, respectively. 3-MQ (10-100 microM) non-competitively inhibited PDE2, but competitively inhibited PDE4. 3-MQ (1-10 microM) also competitively inhibited PDE3. However, 3-MQ (10-100 microM) did not competitively inhibit PDE1 and 5, although it had a tendency to competitively inhibit PDE1 at concentrations of 10 - 30 microM. The present results showed that K i value of 3-MQ was similar to that of milrinone in PDE3, and was not significantly different from that of Ro 20 - 1724 in PDE4, respectively. In conclusion, 3-MQ was revealed to be a selective and competitive PDE3/PDE4 inhibitor, although its inhibitory effect on PDE4 was not potent. Therefore, 3-MQ may have a potential in the treatment of asthma beside its antiviral activity.

S-Isopetasin, a sesquiterpene of Petasites formosanus, allosterically antagonized carbachol in isolated guinea pig atria.

We investigated the antimuscarinic effect of S-isopetasin in isolated guinea pig atria to clarify whether it preferentially acts on muscarinic M 2 or M 3 receptors. The tension changes of isolated atria were isometrically recorded on a polygraph. S-Isopetasin at 50 and 100 microM significantly inhibited baselines of contractile tension and heart rate, but atropine at 1 microM enhanced both. S-Isopetasin (10 - 100 microM) did not significantly alter the concentration-negative inotropic response curves of carbachol (CCh) in left atria. S-Isopetasin (10 - 100 microM) allosterically antagonized negative inotropic and chronotropic responses induced by CCh in spontaneously beating right atria, based on the slopes of Schild plots significantly differing from unity. On the contrary, atropine (0.01 - 1 microM) competitively antagonized all the above responses to CCh. The pA 2 values of S-isopetasin were significantly less than that of S-isopetasin in guinea pig trachealis, suggesting that S-isopetasin may preferentially act on tracheal muscarinic M 3, but not cardiac muscarinic M 2 receptors. However, atropine preferentially acts neither. This finding reveals that S-isopetasin may have benefit in the treatment of asthma.