Differential effect of long-term drug selection with doxorubicin and vorinostat on neuroblastoma cells with cancer stem cell characteristics.

Numerous studies have confirmed that cancer stem cells (CSCs) are more resistant to chemotherapy; however, there is a paucity of data exploring the effect of long-term drug treatment on the CSC sub-population. The purpose of this study was to investigate whether long-term doxorubicin treatment could expand the neuroblastoma cells with CSC characteristics and histone acetylation could affect stemness gene expression during the development of drug resistance. Using n-myc amplified SK-N-Be(2)C and non-n-myc amplified SK-N-SH human neuroblastoma cells, our laboratory generated doxorubicin-resistant cell lines in parallel over 1 year; one cell line intermittently treated with the histone deacetylase inhibitor (HDACi) vorinostat and the other without exposure to HDACi. Cells' sensitivity to chemotherapeutic drugs, the ability to form tumorspheres, and capacity for in vitro invasion were examined. Cell-surface markers and side populations (SPs) were analyzed using flow cytometry. Differentially expressed stemness genes were identified through whole genome analysis and confirmed with real-time PCR. Our results indicated that vorinostat increased the sensitivity of only SK-N-Be(2)C-resistant cells to chemotherapy, made cells lose the ability to form tumorspheres, and reduced in vitro invasion and the SP percentage. CD133 was not enriched in doxorubicin-resistant or vorinostat-treated doxorubicin-resistant cells. Nine stemness-linked genes (ABCB1, ABCC4, LMO2, SOX2, ERCC5, S100A10, IGFBP3, TCF3, and VIM) were downregulated in vorinostat-treated doxorubicin-resistant SK-N-Be(2)C cells relative to doxorubicin-resistant cells. A sub-population of cells with CSC characteristics is enriched during prolonged drug selection of n-myc amplified SK-N-Be(2)C neuroblastoma cells. Vorinostat treatment affects the reversal of drug resistance in SK-N-Be(2)C cells and may be associated with downregulation of stemness gene expression. This work may be valuable for clinicians to design treatment protocols specific for different neuroblastoma patients.

Dexamethasone protection of rat intestinal epithelial cells against oxidant injury is mediated by induction of heat shock protein 72.

Although the therapeutic actions of glucocorticoids are largely attributed to their anti-inflammatory and immunosuppressive effects, they have been implicated in enhancing tissue and cellular protection. In this study, we demonstrate that dexamethasone significantly enhances viability of IEC-18 rat small intestinal cells against oxidant-induced stress in a dose-dependent fashion. This protective action is mediated by induction of hsp72, the major inducible heat shock protein in intestinal epithelial cells. Dexamethasone stimulates a time- and dose-dependent response in hsp72 protein expression that parallels its effects on cell viability. Furthermore, the induction of hsp72 is tissue dependent, as nonintestinal epithelioid HeLa cells show differential induction of hsp72 expression in response to the same dexamethasone treatment. Antisense hsp72 cDNA transfection of IEC-18 cells abolishes the dexamethasone-induced hsp72 response, without significantly affecting constitutive expression of its homologue, hsc73. Dexamethasone treatment also significantly induces hsp72 protein expression in rat intestinal mucosal cells in vivo. These data demonstrate that glucocorticoids protect intestinal epithelial cells against oxidant-induced stress by inducing hsp72.

An overview of extracorporeal membrane oxygenation therapy.

A brief overview of extracorporeal membrane oxygenation and its use in infants and children is presented. The history, selection, operative procedure, daily management and complications are discussed. The international results are shown.

Acute abdomen. Outcomes.

The outcome for children with common surgical conditions that cause an acute abdomen is discussed. These conditions include appendicitis, intussusception, malrotation, inflammatory bowel disease, intestinal obstructions, and nonorganic pain. Emphasis is placed on surgical intervention and disease processes that significantly affect outcome. The outcome of many of the diseases discussed is strongly influenced by the timing of diagnosis and treatment. These children should have prompt care and intervention to prevent morbidity and mortality. In addition, many children who present with common pediatric surgical emergencies have other medical conditions and are best treated in an environment that has a multidisciplinary team to handle their care and decrease the long-term complications.

Glutamine protects intestinal epithelial cells: role of inducible HSP70.

Glutamine (Gln) protects gut mucosa against injury and promotes mucosal healing. Because the induction of heat shock proteins (HSP) protects cells under conditions of stress, we determined whether Gln conferred protection against stress in an intestinal epithelial cell line through HSP induction. Gln added to IEC-18 cells induces an increase in HSP70, a concentration-dependent effect also seen with mRNA. Two forms of injury, lethal heat (49 degrees C) and oxidant, were used, and viability was determined by 51Cr release. Gln-treated cells were significantly more resistant to injury. Treatment with 6-diazo-5-oxo-L-norleucine (DON), a nonmetabolizable analog of Gln, induced HSP70 and protected cells from injury, but less than Gln. These findings suggest that the effects of Gln on HSP70 induction and cellular protection are mediated by metabolic and nonmetabolic mechanisms. To determine whether HSP induction was central to the action of Gln and DON, quercetin, which blocks HSP induction, was used. Quercetin blocked HSP70 induction and the protective effect of Gln and DON. We conclude that the protective effects of Gln in intestinal epithelial cells are in part mediated by HSP70 induction.

Modern treatment modalities for neonatal and pediatric respiratory failure.

BACKGROUND: Respiratory failure secondary to a variety of causes remains a significant cause of morbidity and mortality in the pediatric population. Newer therapies are appearing frequently in an attempt to decrease the number of deaths from this disease state. We briefly review the current literature on some of the newer modalities including: high-frequency ventilation, surfactant, liquid ventilation, and nitric oxide. We then present our experience from the past 11 years in the most invasive, yet successful, therapy for acute respiratory failure-extracorporeal membrane oxygenation (ECMO). METHODS: Retrospective review of all patients treated with ECMO from September 1983 to December 1994 was undertaken. Data were collected from bedside ECMO flow sheets and the standardized data entry forms submitted to the Extracorporeal Life Support Organization. All statistical analyses were performed using a standard statistical software program. RESULTS: During the study period, 194 neonates and 47 pediatric patients were treated with ECMO. The survival rate in the neonatal population is 82% and in the pediatric population it is 40%. The neonatal patients required an average of 153 hours of support while the pediatric patients required 220 hours (P = 0.008). CONCLUSIONS: While the newer treatment modalities discussed may have an important role in treating neonatal and pediatric respiratory failure in the near future, ECMO remains a cornerstone of the modern treatment modalities. Although somewhat invasive, ECMO is effective therapy with increasing survival rates each year.