The molecular pathology of respiratory-chain dysfunction in human mitochondrial myopathies

Some of the different molecular pathologies of respiratory-chain dysfunction in human mitochondrial myopathies will be reviewed in relation to the findings in 58 cases. Deletions of mitochondrial DNA were identified in 21 cases [36%]. There was some correlation between the sites of the deletion and the mitochondrial biochemistry in patients with defects of Complex I but not in cases with more extensive loss of respiratory chain activity. Complex I and Complex IV polypeptides were usually normal in deleted cases. Non-deleted cases, however, often showed specific subunit deficiencies which involved the products of both nuclear and mitochondrial genes. Immunoblots of respiratory-chain polypeptides in one case pointed to defective translocation of the Rieske precursor from the cytosol into the mitochondria. The pathogenic role of circulating autoantibodies to specific matrix proteins and the nature of the target antigens in two patients with mitochondrial encephalomyopathies and respiratory-chain dysfunction will also be discussed.

A mitochondrial encephalomyopathy with specific deficiencies of two respiratory chain polypeptides and a circulating autoantibody to a mitochondrial matrix protein

A 15-yr-old boy with mitochondrial encephalomyopathy and NADH CoQ reductase (Complex I) deficiency is presented. Immunoblotting demonstrated specific deficiencies of the 24 kDa FeS protein of Complex I and subunit II of Complex IV. The patient's serum contained an antibody to a specific mitochondrial matrix polypeptide of apparent Mr 41 kDa. The specific polypeptide deficiencies involve products of nuclear (24 kDa FeS protein) and mitochondrial (subunit II) genes and suggest some intergenomic regulation. The relevance of the circulating antibody to the pathogenesis of the patient's Complex I deficiency is discussed.

Mitochondrial complex I deficiency in Parkinson's disease

The structure and function of mitochondrial respiratory-chain enzyme proteins were studied postmortem in the substantia nigra of nine patients with Parkinson's disease and nine matched controls. Total protein and mitochondrial mass were similar in the two groups. NADH-ubiquinone reductase (Complex I) and NADH cytochrome c reductase activities were significantly reduced, whereas succinate cytochrome c reductase activity was normal. These results indicated a specific defect of Complex I activity in the substantia nigra of patients with Parkinson's disease. This biochemical defect is the same as that produced in animal models of parkinsonism by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and adds further support to the proposition that Parkinson's disease may be due to an environmental toxin with action(s) similar to those of MPTP.

Mitochondrial myopathies: clinical and biochemical features of 30 patients with major deletions of muscle mitochondrial DNA

Analysis of mitochondrial DNA (mtDNA) in muscle and blood from 72 patients with mitochondrial myopathy showed that 30 had major deletions of a variable proportion of muscle mtDNA. All of these 30 patients presented with progressive external ophthalmoplegia and limb weakness, and 8 had the additional features of the Kearns-Sayre syndrome. Of the 42 patients without detectable muscle mtDNA deletions, 10 had progressive external ophthalmoplegia and limb weakness, 2 had the Kearns-Sayre syndrome, 11 had limb weakness without extraocular involvement, and 19 had multisystem disorders predominantly affecting the central nervous system. Only 2 patients with mtDNA deletions had clinically affected relatives, compared with 10 of those without deletions. In the 4 patients with polarographic defects exclusively involving complex I (NADH coenzyme Q reductase), the deleted protein-coding genes were confined to those for complex I subunits. Thirteen other patients with apparently identical deletions had variable clinical and biochemical features. Immunoblots of complex I polypeptides from patients with deletions were either indistinguishable from controls or showed only a mild generalized decrease in all identifiable subunits.

Thermostable reduced nicotinamide adenine dinucleotide oxidase: application to amperometric enzyme assay

The use in amperometric enzyme assays of a highly stable, pH insensitive flavoenzyme, reduced nicotinamide adenine dinucleotide oxidase (NADH oxidase), from the thermophilic organism Thermus aquaticus is described. The enzyme catalyses the oxidation of reduced nicotinamide adenine dinucleotide with concomitant two-electron reduction of dioxygen to hydrogen peroxide. In addition the enzyme used a substituted ferrocene as an alternative mediator of electron transfer. Hydrogen peroxide was detected at +650 mV vs Ag/AgCl at a platinum electrode. The current produced by oxidation of hydrogen peroxide was directly proportional to NADH concentration. The enzyme was used in solution to reoxidize enzymatically generated NADH and served as a basis for amperometric enzyme amplification systems for immunoassay as well as for the detection of substrate concentration for oxidoreductase enzymes. In the presence of alcohol dehydrogenase a rapid production of current occurred upon addition of ethanol over a clinically significant range. Thermus aquaticus NADH oxidase appears to be ideally suited for future exploitation in amperometric sensors for oxidoreductase substrates, offering a number of advantages over previously reported methods.

Diagnosing appendicitis in children with acute abdominal pain

Differentiating acute appendicitis from other causes of acute abdominal pain in children frequently remains unsatisfactory. To determine whether initial historical and physical examination findings might predict final diagnoses, 246 patients with complaints of nontraumatic and nonrecurrent acute abdominal pain were studied. All were between three and 18 years of age and had presented to a hospital-based pediatric emergency department. Each family was telephoned an average of 5.1 days after the visit to determine the patient's subsequent clinical course; operative notes and pathology reports were reviewed for patients receiving surgery. Of these patients with acute abdominal pain, both fever and vomiting were present in 18 of the 24 who eventually had diagnoses of appendicitis, compared with 49 of 222 patients with other final diagnoses (P less than 0.01, with negative predictive value 0.97, sensitivity 0.75, and specificity 0.78, but positive predictive value only 0.27). The duration of the pain at presentation and the frequency of other symptoms (eg, diarrhea, dysuria, anorexia, and lethargy) were unrelated, however, to final diagnosis, as was the duration of the pain and whether abdominal tenderness initially was localized or generalized. Nonruptured appendicitis was generally indistinguishable from ruptured appendicitis preoperatively, by both duration and symptoms. Boys were found more likely to have appendicitis (with or without rupture) than girls (18/118 or 15%, vs. 6/128 or 5%, P less than 0.05). In conclusion, fever and vomiting were noted at presentation more frequently in children with appendicitis than in children with other causes of acute abdominal pain.(ABSTRACT TRUNCATED AT 250 WORDS)

Molecular defects of NADH-ubiquinone oxidoreductase (complex I) in mitochondrial diseases

Defects in Complex I of the mitochondrial respiratory chain have been identified in 38 patients. The clinical and laboratory features are reviewed and the results of recently devised strategies aimed at characterizing the primary molecular and genetic abnormalities are presented. Although not exhaustive, these studies have provided a molecular basis for the contention that defects in Complex I may have their origin in nuclear or in mitochondrial genes.

NADH oxidase from the extreme thermophile Thermus aquaticus YT-1. Purification and characterisation

A protein with NADH oxidase activity from the extreme thermophile Thermus aquaticus YT-1 was purified and characterised. The enzyme was found to have a relative molecular mass of 110,000 and be composed of two subunits of identical size. FAD was found to be present at a concentration of 0.7 mol/mol dimer and was required for activity. During the oxidation of NADH, oxygen uptake takes place with the production of hydrogen peroxide. The enzyme had, with the exception of a higher glutamic acid and tryptophan content, a similar amino acid composition as the NADH oxidase isolated from the mesophile Bacillus megaterium. Purified NADH oxidase was found to have a Km of 39 microM for beta-NADH and a Vmax of 4.68 mumol NADH mg-1 min-1 and was still active at 95 degrees C. Enzymatic activity was found to be independent of pH between 5.0 and 10.5.

Pilot evaluation of instructing parents of newborns about poison prevention strategies

Providing new parents with both written and verbal information about poisons and with syrup of ipecac appeared to be successful when distributed at discharge of their normal newborns. New parents who received neither information nor ipecac served as controls. Distribution occurred during a nine-month period, which was followed after an interval of three months by a four-month evaluation period. The average (+/- SD) time between infant poison exposures and parent telephone calls to the statewide poison center during the evaluation period was 5 +/- 3 minutes for the subjects and 12 +/- 4 for age-matched and socioeconomically matched controls. Both groups had similar frequencies of potentially dangerous exposures for which syrup of ipecac was recommended. Subject parents appeared to have homes which in various respects were significantly more child-safe than those of the controls. Significantly more control homes contained syrup of ipecac after the exposures than before (77% vs 41%).

Molecular basis of mitochondrial myopathies: polypeptide analysis in complex-I deficiency

Clinical and biochemical data are reported for three patients with mitochondrial myopathy. One patient presented only with exercise-induced muscle weakness, whereas the other two showed signs of multisystem disease. Polarographic determination of oxygen uptake in skeletal muscle mitochondria suggested complex-I (nicotinamide adenine dinucleotide [reduced] ubiquinone oxidoreductase) deficiency. Sodium dodecyl sulphate polyacrylamide gel electrophoresis and immunoblotting with antibody to the holoenzyme of complex-I and specific antibodies to certain of the Fe-S subunits of complex-I showed a relatively normal profile in the least affected patient and a generalised reduction in the intensities of all crossreacting bands in the other two patients. The most severely affected patient also showed a disproportionate and pronounced reduction in the 24 K Fe-S subunit. Clinical severity of muscle involvement correlated with the biochemical deficiency as determined polarographically and with the immunoblot appearances.

Chronic administration of the oral hypoglycaemic agent diphenyleneiodonium to rats. An animal model of impaired oxidative phosphorylation (mitochondrial myopathy)

Daily subcutaneous administration of the oral hypoglycaemic agent, diphenyleneiodonium at a low dose (1.5 mg/kg body weight) over a 4-5 week period resulted in a normoglycaemic stable animal model of impaired oxidative phosphorylation in the rat. Diphenyleneiodonium specifically inhibits NAD-linked mitochondrial oxidation [Bloxham, Biochem. Soc. Trans. 7, 103 (1979)], and in isolated mitochondrial preparations from heart, soleus and gastrocnemius muscle and liver from treated animals NAD-linked respiration was reduced by 40% or more of mean control values. Brain and kidney mitochondria isolated from the treated group had similar rates of NAD-linked respiration to their respective control values. The activity of NADH-ferricyanide reductase was significantly reduced in all tissues tested, even in the isolated brain and kidney mitochondria where the activity in these tissues was 60-75% of control values. This suggests that at least 40% of Complex I activity must be inhibited before there is a decline in NAD-linked mitochondrial respiration. This paper discusses the use of diphenyleneiodonium as a means of establishing an animal model of the human disease state, termed mitochondrial myopathy.

An animal model of mitochondrial myopathy: a biochemical and physiological investigation of rats treated in vivo with the NADH-CoQ reductase inhibitor, diphenyleneiodonium

Chronic administration of the NADH-CoQ reductase inhibitor, diphenyleneiodonium to rats at two dose levels, 1.0 and 1.5 mg/kg per day, caused a 40% and 60% reduction, respectively, in the in vitro rate of NAD-linked respiration by skeletal muscle mitochondria. At the highest dose, muscle fatigue, lactic acidosis and an over-utilization of phosphocreatine was observed in the gastrocnemius muscle during mild stimulation of 1 Hz frequency. The resynthesis of phosphocreatine following muscle stimulation was about 2 fold slower in the treated animal group. At the low dose, no significant biochemical changes were observed during muscle stimulation at 4 Hz. The results are discussed in terms of skeletal muscle "oxidative reserve", twitch tension maintenance and the relevance to the human diseased state of mitochondrial myopathy.

Incidence, significance and remission of tubal spasm during attempted hysteroscopic tubal sterilization

Four hundred three attempted hysteroscopic tubal sterilizations were performed. Tubal spasm was encountered in 37 cases (9.2%) and prevented bilateral placement of tubal plugs in 16 of those cases. There was some evidence that glucagon was associated with a higher rate of remission and that women using barrier birth control methods experienced a lower incidence of tubal spasm. A number of other factors were found to be unrelated to tubal spasm and its remission.

Hysteroscopic tubal occlusion with formed-in-place silicone plugs: a clinical review

The present study is a detailed review of 415 patients undergoing sterilization under local anesthesia with hysteroscopically placed silicone plugs. The authors compiled 3200 woman-months after sterilization without a pregnancy. Up to 90% of women undergoing this procedure in the office have successful completion. The difficulties with the method are outlined, unsuccessful procedures categorized, and radiographs presented, and the outlook for the future is discussed. The method is seen as a viable alternative to laparoscopic sterilization.

The incidence of intrauterine abnormalities found at hysteroscopy in patients undergoing elective hysteroscopic sterilization

Hysteroscopic findings in 323 consecutive women requesting transcervical sterilization were analyzed. A remarkably low incidence of intrauterine abnormalities (13%) was found in this group of asymptomatic women as compared to that found in large series of women who experienced abnormal uterine bleeding or infertility. The dramatic difference in the incidence of abnormal hysteroscopic findings between these patient groups supports the concept of routinely performing hysteroscopy when evaluating women with infertility or abnormal uterine bleeding. It also sets a baseline for the prevalence of hysteroscopically demonstrable intrauterine pathology in an asymptomatic population.

The role of antibody in the interaction of Salmonella and listeria with peritoneal macrophages

That in vitro killing by normal and activated macrophages of S. typhimurium and other gram-negative organisms is dependent on the presence of antibody has been confirmed. It has been shown that antibody is required for the binding of S. typhimurium to the surfaces of macrophages. This binding can be inhibited by the Fc portion of immunoglobulin, indicating that the Fc receptors on macrophages are used for binding S. typhimurium. It has also been confirmed that antibody does not appear to be necessary for killing of L. monocytogenes to occur. The organisms bind to the surface of macrophages by different receptors. Binding of L. monocytogenes occurs in the absence of added antibody and Fc fragments of immunoglobulin do not affect the binding. Attachment can be inhibited, however, by removal of divalent cations, a treatment that has no effect on antibody-mediated binding as, under these conditions, the binding of L. monocytogenes to macrophages can be enhanced by antibody. The significance of these findings is discussed.

Local immunity to klebsiella pneumoniae in the lungs of mice

The development of local immunity to Klebsiella pneumoniae in the lower respiratory tract is described. Immunity to intranasal infection is produced by systemic immunization resulting in high titers of circulating antibody. Protection also follows intranasal immunization with glutaraldehyde-killed organisms. Low levels of antibodies develop in serum after intranasal immunization. IgA antibody can be detected in the serum of these mice whereas little IgA antibody is detected in the serum of mice immunized systemically. Both IgA and IgG antibodies can be found in the pulmonary secretions of locally immunized mice. IgA and IgG from these secretions may be used to passively transfer protection when used to opsonize the infecting dose of K. pneumoniae. Protection mediated by IgA is not due to any interaction of IgA with cells present in the lower respiratory tract during infection, but exerts its protective effect in the upper respiratory tract, thereby preventing the spread of bacterial infection to the lower respiratory tract.