Import of cytochrome c into mitochondria

The import of cytochrome c into mitochondria can be resolved into a number of discrete steps. Here we report on the covalent attachment of heme to apocytochrome c by the enzyme cytochrome c heme lyase in mitochondria from Neurospora crassa. A new method was developed to measure directly the linkage of heme to apocytochrome c. This method is independent of conformational changes in the protein accompanying heme attachment. Tryptic peptides of [35S]cysteine-labelled apocytochrome c, and of enzymatically formed holocytochrome c, were resolved by reverse-phase HPLC. The cysteine-containing peptide to which heme was attached eluted later than the corresponding peptide from apocytochrome c and could be quantified by counting 35S radioactivity as a measure of holocytochrome c formation. Using this procedure, the covalent attachment of heme to apocytochrome c, which is dependent on the enzyme cytochrome c heme lyase, could be measured. Activity required heme (as hemin) and could be reversibly inhibited by the analogue deuterohemin. Holocytochrome c formation was stimulated 5–10-fold by NADH > NADPH > glutathione and was independent of a potential across the inner mitochondrial membrane. NADH was not required for the binding of apocytochrome c to mitochondria and was not involved in the reduction of the cysteine thiols prior to heme attachment. Holocytochrome c formation was also dependent on a cytosolic factor that was necessary for the heme attaching step of cytochrome c import. The factor was a heat-stable, protease-insensitive, low-molecular-mass component of unknown function. Cytochrome c heme lyase appeared to be a soluble protein located in the mitochondrial intermembrane space and was distinct from the previously identified apocytochrome c binding protein having a similar location. A model is presented in which the covalent attachment of heme by cytochrome c heme lyase also plays an essential role in the import pathway of cytochrome c

Pit picking vs. Limberg flap vs. primary open method to treat pilonidal sinus disease - A cohort of 327 consecutive patients.

Background Minimally invasive methods in pilonidal sinus disease (PSD) surgery are becoming standard. Although long-term results are available for some techniques, long-term outcome data of patients after pit picking is lacking. We aimed at investigating perioperative and long-term outcomes of patients undergoing pit picking, Limberg flap or primary open surgery to treat PSD. Methods In a single-centre observational study, we evaluated the outcomes of 327 consecutive patients undergoing PSD surgery between 2011 and 2020. Results PSD had recurred in 22% of Limberg flap patients and 62% of pit picking patients at 5 years (p=0.0078; log rank test). Previous pilonidal surgeries, smoking, body mass index, immunodeficiency, and diabetes did not significantly influence the long-term recurrence rate. Primary open treatment was performed for 72% of female patients presenting with primary disease. Conclusions Due to its especially dismal long-term results, pit picking should be abandoned, and Limberg flap should be promoted instead, even for primary disease and in females

Pit picking vs. Limberg flap vs. primary open method to treat pilonidal sinus disease – A cohort of 327 consecutive patients

Abstract Background Minimally invasive methods in pilonidal sinus disease (PSD) surgery are becoming standard. Although long-term results are available for some techniques, long-term outcome data of patients after pit picking is lacking. We aimed at investigating perioperative and long-term outcomes of patients undergoing pit picking, Limberg flap or primary open surgery to treat PSD. Methods In a single-centre observational study, we evaluated the outcomes of 327 consecutive patients undergoing PSD surgery between 2011 and 2020. Results PSD had recurred in 22% of Limberg flap patients and 62% of pit picking patients at 5 years (p=0.0078; log rank test). Previous pilonidal surgeries, smoking, body mass index, immunodeficiency, and diabetes did not significantly influence the long-term recurrence rate. Primary open treatment was performed for 72% of female patients presenting with primary disease. Conclusions Due to its especially dismal long-term results, pit picking should be abandoned, and Limberg flap should be promoted instead, even for primary disease and in females. </jats:sec