Mutants of Cytochrome P450 Reductase Lacking Either Gly-141 or Gly-143 Destabilize Its FMN Semiquinone.

NADPH-cytochrome P450 oxidoreductase transfers electrons from NADPH to cytochromes P450 via its FAD and FMN. To understand the biochemical and structural basis of electron transfer from FMN-hydroquinone to its partners, three deletion mutants in a conserved loop near the FMN were characterized. Comparison of oxidized and reduced wild type and mutant structures reveals that the basis for the air stability of the neutral blue semiquinone is protonation of the flavin N5 and strong H-bond formation with the Gly-141 carbonyl.

Effects of membrane mimetics on cytochrome P450-cytochrome b5 interactions characterized by NMR spectroscopy.

Mammalian cytochrome P450 (P450) is a membrane-bound monooxygenase whose catalytic activities require two electrons to be sequentially delivered from its redox partners: cytochrome b5 (cytb5) and cytochrome P450 reductase, both of which are membrane proteins. Although P450 functional activities are known to be affected by lipids, experimental evidence to reveal the effect of membrane on P450-cytb5 interactions is still lacking. Here, we present evidence for the influence of phospholipid bilayers on complex formation between rabbit P450 2B4 (CYP2B4) and rabbit cytb5 at the atomic level, utilizing NMR techniques.

Kinetic and structural characterization of the interaction between the FMN binding domain of cytochrome P450 reductase and cytochrome c.

Cytochrome P450 reductase (CPR) is a diflavin enzyme that transfers electrons to many protein partners. Electron transfer from CPR to cyt c has been extensively used as a model reaction to assess the redox activity of CPR. CPR is composed of multiple domains, among which the FMN binding domain (FBD) is the direct electron donor to cyt c.

A canine model to assess the biochemical stress response to laparoscopic and open surgery.

Purpose: To develop an animal model to assess the stress response to open and laparoscopic surgery. Such a model would allow objective physiologic assessment of the putative benefits of laparoscopy and provide a framework in which to compare modifications in operative and anesthetic technique that might decrease the stress of surgery.

Materials And Methods: Mongrel dogs underwent laparoscopic (N = 12) or open surgical (N = 12) left nephrectomy.

Comparison of 2-octyl cyanoacrylate adhesive, fibrin glue, and suturing for wound closure in the porcine urinary tract.

Objectives: To evaluate 2-octyl cyanoacrylate glue (OCG) for wound closure in the urinary tract and compare the ability of OCG, fibrin glue (FG), and suture to withstand physiologic and supraphysiologic stress, because the use of tissue adhesives such as OCG or FG might simplify laparoscopic surgery.

Methods: Female domestic pigs (n = 22) underwent a 7.5-cm cystotomy.

Generation of growth hormone pulsatility in women: evidence against somatostatin withdrawal as pulse initiator.

To test whether endogenous hypothalamic somatostatin (SRIH) fluctuations are playing a role in the generation of growth hormone (GH) pulses, continuous subcutaneous octreotide infusion (16 microg/h) was used to create constant supraphysiological somatostatinergic tone. Six healthy postmenopausal women (age 67 +/- 3 yr, body mass index 24.7 +/- 1.

Prospective multicenter surveillance study of funguria in hospitalized patients. The National Institute for Allergy and Infectious Diseases (NIAID) Mycoses Study Group.

Although fungal urinary tract infections are an increasing nosocomial problem, the significance of funguria is still not clear. This multicenter prospective surveillance study of 861 patients was undertaken to define the epidemiology, management, and outcomes of funguria. Diabetes mellitus was present in 39% of patients, urinary tract abnormalities in 37.

Almost totally tubeless percutaneous nephrolithotomy: further evolution of the technique.

Background And Objectives: There is renewed interest in the concept of foregoing placement of the postoperative nephrostomy tube (PNT) after percutaneous nephrolithotomy (PCNL) with the intent of reducing postoperative discomfort and hospital stay. We have omitted the PNT and placed an internal ureteral stent or externalized ureteral catheter after PCNL in selected patients. We reviewed our experience in order to assess the efficacy and safety of this practice.

Pneumoperitoneum does not potentiate the nephrotoxicity of aminoglycosides in rats.

Objectives: Pneumoperitoneum is associated with transient renal dysfunction. To our knowledge, the safety of administering nephrotoxins such as aminoglycosides during pneumoperitoneum has not been studied. Our hypothesis was that pneumoperitoneum potentiates the nephrotoxicity of aminoglycosides.

Dialysis dose, membrane type, and anemia control.

Erythropoietin has become an important part of the treatment of patients with end-stage renal disease (ESRD). Erythropoietin treatment and the concomitant increase in red blood cell mass have been associated with improvements in a variety of important clinical outcomes that bear on the morbidity and mortality of dialysis patients. However, many patients do not reach the target hematocrit goals, and there is a large variation among patients in the amount of erythropoietin administered.