In Vitro-Reconstituted Nucleoids Can Block Mitochondrial DNA Replication and Transcription

SummaryThe mechanisms regulating the number of active copies of mtDNA are still unclear. A mammalian cell typically contains 1,000–10,000 copies of mtDNA, which are packaged into nucleoprotein complexes termed nucleoids. The main protein component of these structures is mitochondrial transcription factor A (TFAM). Here, we reconstitute nucleoid-like particles in vitro and demonstrate that small changes in TFAM levels dramatically impact the fraction of DNA molecules available for transcription and DNA replication. Compaction by TFAM is highly cooperative, and at physiological ratios of TFAM to DNA, there are large variations in compaction, from fully compacted nucleoids to naked DNA. In compacted nucleoids, TFAM forms stable protein filaments on DNA that block melting and prevent progression of the replication and transcription machineries. Based on our observations, we suggest that small variations in the TFAM-to-mtDNA ratio may be used to regulate mitochondrial gene transcription and DNA replication

Multivisceral Resection with Performing a Double Roux-en-Y Reconstruction for Advanced Gastric Cancer

Background. The role of multivisceral resection, in the setting of locally advanced gastric cancer, is still debated. Previous studies have reported a higher risk for perioperative morbidity and mortality, with limited objective benefit in terms of survival. Patient. A male patient, 55 years old, was admitted to the clinic of surgery for surgical treatment of bleeding gastric ulceration. Preoperative diagnostic evaluation was performed, and patient had undergone a surgical treatment which revealed a large mass in head of the pancreas, infiltrating the hepatoduodenal ligament and transverse mesocolon. Total gastrectomy, duodenopancreatectomy, and right hemicolectomy were performed. The digestive tube continuity was reestablished by deriving the double Roux limbs. Conclusion. The aim of this case presentation is to demonstrate a method of digestive tube reconstruction by performing the double Roux-en-Y reconstruction in advanced gastric cancer when the multivisceral resection is performed