The purpose of this work was to show how the quantitative definition of the different parameters involved in mitochondrial oxidative phosphorylation makes it possible to characterize the mechanisms by which the yield of ATP synthesis is affected. Three different factors have to be considered: (i) the size of the different forces involved (free energy of redox reactions and ATP synthesis, proton electrochemical difference); (ii) the physical properties of the inner mitochondrial membrane in terms of leaks (H+ and cations); and finally (iii) the properties of the different proton pumps involved in this system (kinetic properties, regulation, modification of intrinsic stoichiometry). The data presented different situations where one or more of these parameters are affected, leading to a different yield of oxidative phosphorylation.
View Article and Find Full Text PDFOn isolated mitochondria, numerous studies of the relationships between fluxes and their associated forces have led to the description of some properties of the oxidative phosphorylation pathway. However whether such an approach can be applied to understanding the actual situation in intact living cells needs further consideration. In this study on isolated hepatocytes, we describe the dependence of the respiratory rate on the three thermodynamic forces linked to oxidative phosphorylation (i.
View Article and Find Full Text PDFCoronary dysfunctions identified in the presence of chronic heart failure are an important pathophysiologic abnormality that influences the prognosis of the disease. Because the endothelin pathway plays a significant role in the increased peripheral vascular tone associated with heart failure, we hypothesized that the endothelin pathway may be involved in the abnormal coronary vasomotion associated with this pathologic condition. Experiments were carried out in failing hearts (UM-X7.
View Article and Find Full Text PDFWe have investigated the role of arginine residues in the regulation of the mitochondrial permeability transition pore, a cyclosporin A-sensitive inner membrane channel. Isolated rat liver mitochondria were treated with the arginine-specific chemical reagent 2, 3-butanedione or phenylglyoxal, followed by removal of excess free reagent. After this treatment, mitochondria accumulated Ca2+ normally, but did not undergo permeability transition following depolarization, a condition that normally triggers opening of the permeability transition pore.
View Article and Find Full Text PDFWe have investigated the regulation of the permeability transition pore (PTP), a cyclosporin A-sensitive channel, in rat skeletal muscle mitochondria. As is the case with mitochondria isolated from a variety of sources, skeletal muscle mitochondria can undergo a permeability transition following Ca2+ uptake in the presence of Pi. We find that the PTP opening is dramatically affected by the substrates used for energization, in that much lower Ca2+ loads are required when electrons are provided to complex I rather than to complex II or IV.
View Article and Find Full Text PDFPurpose: We assessed the long-term results of renal transplantation in children with augmentation cystoplasty.
Materials And Methods: We retrospectively reviewed the complications and followup in 14 pediatric renal transplant recipients with augmentation cystoplasty. The etiology of bladder dysfunction included posterior urethral valves in 10 cases, neurogenic bladder in 3 and vesicoureteral reflux in 1.
Background: The association of compulsive water drinking with bulimia nervosa is rarely encountered. Nevertheless similar behavior patterns could involve a common pathophysiological mechanism.
Methods: A case report with the association of those two disorders is described.
The purpose of this work was to investigate the mechanism of regulation of mitochondrial respiration in vivo in different muscles of normal rat and mice, and in transgenic mice deficient in desmin. Skinned fiber technique was used to study the mitochondrial respiration in the cells in vivo in the heart, soleus and white gastrocnemius skeletal muscles of these animals. Also, cardiomyocytes were isolated from the normal rat heart, permeabilized by saponin and the "ghost" (phantom) cardiomyocytes were produced by extraction of myosin with 800 mM KCl.
View Article and Find Full Text PDFBackground: Several studies suggest that coronary perfusion is abnormal in heart failure. The fact that these deficits may results in an altered coronary reserve remains controversial. Therefore, coronary adaptability to short-duration ischemia and the resultant myocardial reactive hyperemia were investigated in a model of chronic heart failure.
View Article and Find Full Text PDFPurpose: We assessed the long-term efficacy of renal transplantation in children with the prune-belly syndrome.
Materials And Methods: We retrospectively compared the outcomes of renal transplantation in 9 children with the prune-belly syndrome and 100 with malformative uropathy.
Results: Graft survival in the prune-belly syndrome and control groups was 50 and 72% at 5 years, and 50 and 47% at 10 years, respectively (not statistically significant).
Objectives: To assess the results of jejunal conduit urinary diversion, with particular attention to electrolyte imbalance and long-term renal function.
Methods: From 1976 to 1994, 50 patients underwent urinary diversion using a short jejunal loop (10 to 12 cm) placed transperitoneally. Of these patients, 18 received pelvic irradiation before diversion.
This study was conducted to determine the relationship between lactobacilli and bacterial species associated with bacterial vaginosis in pregnancy and the prevalence of H2O2-producing and non-producing strains of lactobacilli in pregnant women whose vaginal flora had already been analysed. Information was available for 174 pregnant women whose vaginal flora had been evaluated previously by examining gram-stained vaginal smears: 50 had grade III flora (bacterial vaginosis). 50 grade II flora, 41 flora graded as abnormal which then reverted to grade I (revertants) and 33 normal flora (controls).
View Article and Find Full Text PDFThe mitochondrial permeability transition pore, a cyclosporin A-sensitive channel, is controlled by the transmembrane electric potential difference across the inner membrane. Here, we show that treatment of rat liver mitochondria with the arginine reagent phenylglyoxal inhibits the permeability transition pore triggered by depolarization with uncoupler after Ca2+ accumulation. Phenylglyoxal does not change the extent of mitochondrial Ca2+ uptake or the extent of membrane depolarization, indicating that covalent modification of arginine (and possibly lysine) residues directly affects the open probability of the pore.
View Article and Find Full Text PDFBiochem Biophys Res Commun
March 1997
Dissipation of energy during oxidative phosphorylation may be due to two distinct mechanisms: passive permeability to protons and/or cations (leak) or decrease in the efficiency of some proton pumps (slip). Whatever the mechanism involved, it is admitted that the wastage depends on the protonmotive force. However, the most relevant question in physiology is to determine whether other factors contribute or not to this efficiency.
View Article and Find Full Text PDFJ Acquir Immune Defic Syndr Hum Retrovirol
March 1997
A double-blind, placebo-controlled study was designed to evaluate the safety and tolerability of intravaginal dextrin sulphate (D2S) gel to assess its preliminary suitability as a potential vaginal virucide. Tolerability was assessed by questionnaire and patient interview. Colposcopy with vaginal biopsy was performed to assess the macroscopic and microscopic evidence of inflammation.
View Article and Find Full Text PDFObjectives: Several studies suggest that regulation of coronary vasomotion is abnormal in heart failure, but controversies exist as to whether an altered endothelium-dependent dilation of the coronary vasculature contributes to these abnormalities. In the present study we evaluated the coronary reactivity to endothelium-dependent and -independent vasoactive substances in a model of chronic heart failure.
Methods: Isolated hearts from > 200-day-old cardiomyopathic hamsters (UM-X7.
Purpose: We assessed the long-term efficacy of renal transplantation in children with posterior urethral valves.
Materials And Methods: We retrospectively compared the outcomes of renal transplantation in 66 children with posterior urethral valves and 116 with malformation uropathies (controls).
Results: Graft survival in the posterior urethral valves and control groups was 69 and 72% at 5 years, and 54 and 50% at 10 years, respectively (not statistically significant).
Purpose: We assessed results of a combined modified rectus fascial sling procedure and augmentation ileocystoplasty in women with neurogenic urinary incontinence.
Materials And Methods: We prospectively evaluated 21 patients (mean followup 28.6 months).
Objective: The authors evaluated the results of augmentation ileocystoplasty in patients presenting with neurogenic urinary incontinence.
Materials And Methods: A prospective study was conducted in 36 patients (25 women, 11 men) 30 of whom simultaneously underwent a bladder neck continence procedure. The mean follow-up was 32.
Biochim Biophys Acta
September 1996
Liver mitochondria isolated from controls or polyunsaturated fatty acid (PUFA) deficient rats were studied for oxidative phosphorylation. A PUFA-deficient diet led to a dramatic change in the fatty acid composition of mitochondrial lipid content, similar to that reported in the literature. Besides the changes in lipid composition, mitochondrial volume was enlarged (+45% in state 4 and two-fold in state 3).
View Article and Find Full Text PDFThe effects of a 4-week deficiency in polyunsaturated fatty acids (PUFA) in isolated rat hepatocytes have been investigated for oxidative phosphorylation and fatty acid, dihydroxyacetone (DHA) or glycerol metabolism. Oxygen uptake was significantly increased (by 20%) with or without fatty acid addition (octanoate or oleate) in the PUFA-deficient group compared with controls. The effect persisted after oligomycin addition but not after that of potassium cyanide, leading to the conclusion that, in these intact cells, the mitochondria were uncoupled.
View Article and Find Full Text PDFVery recent experimental data, obtained by using the permeabilized cell technique or tissue homogenates for investigation of the mechanisms of regulation of respiration in the cells in vivo, are shortly summarized. In these studies, surprisingly high values of apparent Km for ADP, exceeding that for isolated mitochondria in vitro by more than order of magnitude, were recorded for heart, slow twitch skeletal muscle, hepatocytes, brain tissue homogenates but not for fast twitch skeletal muscle. Mitochondrial swelling in the hypo-osmotic medium resulted in the sharp decrease of the value of Km for ADP in correlation with the degree of rupture of mitochondrial outer membrane, as determined by the cytochrome c test.
View Article and Find Full Text PDFPurpose: We assessed the results of endoscopic sphincterotomy in patients with detrusor-sphincter dyssynergia secondary to spinal cord injury.
Materials And Methods: A prospective study was done of 92 patients with a mean followup of 20.6 months.