Imipramine Treatment Alters Sphingomyelin, Cholesterol, and Glycerophospholipid Metabolism in Isolated Macrophage Lysosomes

Lysosomes are degradative organelles that facilitate the removal and recycling of potentially cytotoxic materials and mediate a variety of other cellular processes, such as nutrient sensing, intracellular signaling, and lipid metabolism. Due to these central roles, lysosome dysfunction can lead to deleterious outcomes, including the accumulation of cytotoxic material, inflammation, and cell death. We previously reported that cationic amphiphilic drugs, such as imipramine, alter pH and lipid metabolism within macrophage lysosomes. Therefore, the ability for imipramine to induce changes to the lipid content of isolated macrophage lysosomes was investigated, focusing on sphingomyelin, cholesterol, and glycerophospholipid metabolism as these lipid classes have important roles in inflammation and disease. The lysosomes were isolated from control and imipramine-treated macrophages using density gradient ultracentrifugation, and mass spectrometry was used to measure the changes in their lipid composition. An unsupervised hierarchical cluster analysis revealed a clear differentiation between the imipramine-treated and control lysosomes. There was a significant overall increase in the abundance of specific lipids mostly composed of cholesterol esters, sphingomyelins, and phosphatidylcholines, while lysophosphatidylcholines and ceramides were overall decreased. These results support the conclusion that imipramine's ability to change the lysosomal pH inhibits multiple pH-sensitive enzymes in macrophage lysosomes.

Reporting tools for clinical quality improvement

To support clinical quality improvement (QI), effective quality analysis tools are essential. New strategies that we have incorporated into our routine assessment activities include comparative screening, clinical process benchmarking tables, and run charts for key quality indicators. To target areas for improvement, we use comparative screening. We have access to clinical data for 11 comparable medical centers. Currently, these data are used to identify our ranking relative to the others for mortality, readmission, and length of stay. Diagnosis-related groups and ICD-9-CM clusters serve as clinical groupings with defined minimal case volume requirements to ensure meaningful comparisons. These comparative reports permit our clinical leaders and hospital administrators to focus QI activities. Clinical process benchmarking involves peer-to-peer interfacility communication to identify those factors that create outstanding clinical performance. We successfully have used this tool to support process improvement in cardiac-surgery, administration of patient controlled analgesia, and respiratory therapy. Interdisciplinary QI teams identify the key investigative questions. Team members then contact their counterparts at similar facilities, which differ from our hospital in quality, based on empirical evidence or through comparative screening. The information that is obtained is collated in a tabular format, along with our own information, to permit easy identification of key clinical processes associated with better outcomes. Key quality and utilization goals at our hospital include reducing unplanned readmissions by 10%, achieving a 5% lower average length of stay, and not exceeding Health Care Financing Administration expected mortality rates in any clinical area.(ABSTRACT TRUNCATED AT 250 WORDS)