Dissecting the Factors Affecting the Fluorescence Stability of Quantum Dots in Live Cells.

Labeling and imaging of live cells with quantum dots (QDs) has attracted great attention in the biomedical field over the past two decades. Maintenance of the fluorescence of QDs in a biological environment is crucial for performing long-term cell tracking to investigate the proliferation and functional evolution of cells. The cell-penetrating peptide transactivator of transcription (TAT) is a well-studied peptide to efficiently enhance the transmembrane delivery. Here, we used TAT peptide-conjugated QDs (TAT-QDs) as a model system to examine the fluorescence stability of QDs in live cells. By confocal microscopy, we found that TAT-QDs were internalized into cells by endocytosis, and transported into the cytoplasm via the mitochondria, Golgi apparatus, and lysosomes. More importantly, the fluorescence of TAT-QDs in live cells was decreased mainly by cell proliferation, and the low pH value in the lysosomes could also lower the fluorescence intensity of intracellular QDs. Quantitative analysis of the amount of QDs in the extracellular region and whole cells indicated that the exocytosis was not the primary cause of fluorescence decay of intracellular QDs. This work facilitates a better understanding of the fluorescence stability of QDs for cell imaging and long-term tracking in live cells. Also, it provides insights into the utility of TAT for transmembrane transportation, and the preparation and modification of QDs for cell imaging and tracking.

Laparoscopic management of type I choledochal cyst in adults: cyst resection, assisted Roux-en-Y reconstruction and hepaticojejunostomy.

Due to improvement of instrumentation and surgeons' skills, the correction of congenital biliary tract anomalies has been performed by the laparoscopic approach. Because of the high rate of associated malignancy of the biliary system in middle-aged adults, treatment for choledochal cyst is necessary, especially in adult patients. We report on the laparoscopic excision and hepaticoduodenostomy of type I choledochal cysts in five adult patients. To facilitate the procedure, the creation of a Roux-en-Y reconstruction was performed with a minimal abdominal incision. All patients had an uneventful recovery with no major complications. Most were discharged on day 8 after the procedure. At a follow-up of two years, they were still asymptomatic, showing no cholangitis or anicteric. Laparoscopic management for choledochal cyst is an advantageous approach, so it is feasible and will probably become an accepted method in further clinical application.