Quality assurance of RNA expression profiling in clinical laboratories

RNA expression profiles are increasingly used to diagnose and classify disease, based on expression patterns of as many as several thousand RNAs. To ensure quality of expression profiling services in clinical settings, a standard operating procedure incorporates multiple quality indicators and controls, beginning with preanalytic specimen preparation and proceeding thorough analysis, interpretation, and reporting. Before testing, histopathological examination of each cellular specimen, along with optional cell enrichment procedures, ensures adequacy of the input tissue. Other tactics include endogenous controls to evaluate adequacy of RNA and exogenous or spiked controls to evaluate run- and patient-specific performance of the test system, respectively. Unique aspects of quality assurance for array-based tests include controls for the pertinent outcome signatures that often supersede controls for each individual analyte, built-in redundancy for critical analytes or biochemical pathways, and software-supported scrutiny of abundant data by a laboratory physician who interprets the findings in a manner facilitating appropriate medical intervention. Access to high-quality reagents, instruments, and software from commercial sources promotes standardization and adoption in clinical settings, once an assay is vetted in validation studies as being analytically sound and clinically useful. Careful attention to the well-honed principles of laboratory medicine, along with guidance from government and professional groups on strategies to preserve RNA and manage large data sets, promotes clinical-grade assay performance.     

Systematic review and pooled analysis assessing the association between elderly age and outcome following surgical resection of esophageal malignancy

The incidence of esophageal malignancy continues to increase worldwide. At the same time, average life expectancy levels continue to climb, ensuring that more patients will present in their 70s, 80s, and 90s. The aim of this pooled analysis is to compare short‐ and long‐term outcomes for elderly and younger patients undergoing esophagectomy for malignancy. Studies comparing the outcomes of esophagectomy for malignancy in elderly and young cohorts of patients were included. The minimum threshold age used to define the elderly cohort was 70 years. Primary outcomes were in‐hospital mortality, overall and cancer‐related 5‐year survival. Secondary outcomes were the length of hospital stay, the incidence of anastomotic leak, conduit ischemia, cardiac and pulmonary complications, and the use of neoadjuvant therapy. Twenty‐five publications comprising 9531 and 2573 operations on younger and elderly cohorts of patients respectively were analyzed. Elderly patients were less likely to receive neoadjuvant therapy (14.6% vs. 29.47%; pooled odds ratio [POR]= 0.48; 95% confidence interval [C.I.]= 0.35–0.65; P < 0.05). Esophagectomy in elderly patients was associated with increased in‐hospital mortality (7.83% vs. 4.21%; POR = 1.87; 95% C.I. = 1.54–2.26; P < 0.05), as well as increased pulmonary (21.77% vs. 19.49%) and cardiac (18.7% vs. 13.17%) complications. Subset analysis of studies using an age threshold of 80 years showed an even more significant association between in‐hospital mortality and elderly age (pooled odds ratio = 3.19; 95% C.I. = 1.6–6.35; P < 0.05). There were no significant differences between the groups in length of hospital stay, incidence of anastomotic leak, or conduit ischemia. The elderly group showed reduced overall 5‐year survival (21.23% vs. 29.01%; pooled odds ratio = 0.73; 95% C.I. = 0.62–0.87; P < 0.05) and reduced cancer‐free 5‐year survival (34.4% vs. 41.8%; POR = 0.75; 95% C.I. = 0.64–0.89; P < 0.05). Elderly patients are at increased risk of pulmonary and cardiac complications, and perioperative mortality following esophagectomy, and show reduced cancer‐related 5‐year survival compared with younger patients. These patients represent a high‐risk cohort, who requires thorough assessment of medical comorbidity, targeted counseling, and optimized treatment pathways.     

Novel amiloride-sensitive sodium-dependent proton secretion in the mouse proximal convoluted tubule

The proximal convoluted tubule (PCT) reabsorbs most of the filtered bicarbonate. Proton secretion is believed to be mediated predominantly by an apical membrane Na(+)/H(+) exchanger (NHE). Several NHE isoforms have been cloned, but only NHE3 and NHE2 are known to be present on the apical membrane of the PCT. Here we examined apical membrane PCT sodium-dependent proton secretion of wild-type (NHE3(+/+)/NHE2(+/+)), NHE3(-/-), NHE2(-/-), and double-knockout NHE3(-/-)/NHE2(-/-) mice to determine their relative contribution to luminal proton secretion. NHE2(-/-) and wild-type mice had comparable rates of sodium-dependent proton secretion. Sodium-dependent proton secretion in NHE3(-/-) mice was approximately 50% that of wild-type mice. The residual sodium-dependent proton secretion was inhibited by 100 microM 5-(N-ethyl-N-isopropyl) amiloride (EIPA). Luminal sodium-dependent proton secretion was the same in NHE3(-/-)/NHE2(-/-) as in NHE3(-/-) mice. These data point to a previously unrecognized Na(+)-dependent EIPA-sensitive proton secretory mechanism in the proximal tubule that may play an important role in acid-base homeostasis.     

Modification of an anesthesia machine for MRI suite.

The modification of a wall mounted anesthesia machine, rendering it nonmagnetic for use in the magnetic resonance imaging suite, is described. The modified anesthesia machine functioned properly at 1.8 m distance from 1.5 tesla electromagnet without degrading its imaging.