A plausible two-state model for cytochrome c oxidase

The catalytic properties of pulsed and resting cytochrome c oxidase (ferrocytochrome c: oxygen oxidoreductase, EC 1.9.3.1), expressed in terms of a minimal kinetic scheme and simulated by numerical computations, were successfully described. A two-state model, in which the relative amounts of the enzyme present in each conformation are regulated by the rates of electron flux and O2 binding on one side and the interconversion rates on the other, accounts for the activation of cytochrome c oxidase during turnover.

A study of the electron transfer properties of the heme undecapeptide from cytochrome c by 1H nmr spectroscopy

Nuclear magnetic resonance (nmr) spectroscopy has been used to investigate the heme undecapeptide from cytochrome c. Assignments of resonances to specific residues have been made based on spin decoupling, redox titration, and the pH and temperature dependence of resonance lines. An outline structure is presented based on the assignments, secondary shift data, and the x-ray crystal structure of cytochrome c. An equation is derived to relate the width of an nmr line during a redox titration to the percentage of each oxidation state. Using this equation the self-exchange rate constant for electron transfer for the heme peptide is 1.3 x 10(7) M-1 sec-1 at 330 degrees K. Discussion of the self-exchange rate constants of cytochrome c, cytochrome c3, and cytochrome c551 is related to this constant for the heme undecapeptide.

Splenectomy and antiplatelet agents in thrombotic thrombocytopenic purpura

Ten patients with thrombotic thrombocytopenic purpura (TTP) were studied retrospectively. The male:female ratio was 2:3 and the median age was 27 years. Six patients were alive one-half to 18 years after the onset of the disease. Four of these patients underwent emergency splenectomy and received antiplatelet drugs. Of the remaining two, one responded to splenectomy and the other had received a short course of aspirin therapy. The study supports the usefulness of splenectomy and/or antiplatelet agents in the treatment of TTP.

Diagnosis of electric neurostimulating device dysfunction

The recent advances in the area of electric neurostimulating devices have added important tools to the neurosurgeon in the treatment of numerous clinical problems. The diagnosis of equipment dysfunction poses a unique problem for the physician. This communication presents methods of testing these electric neurostimulating systems using the basic equipment found in any electronics laboratory.

Coordinacy of lysosomal enzyme excretion in human urine

Assay conditions have been developed for the determination of urinary beta-glucuronidase, beta-galactosidase, alpha-galactosidase, and beta-hexosaminidase using fluorometric substrates. The assay conditions for beta-glucuronidase overcome interference by both low and high molecular weight inhibitors, a problem that has confused earlier studies of enzyme excretion. The four lysosomal enzymes are excreted corrdinately: although their absolute levels (in units per milligram of creatinine) vary during the day and from one day to the next, the ratio of one enzyme to another remains relatively constant. The lack of correlation betweem plasma and urine enzyme levels, together with the high molecular weights of these enzymes, suggests that the urinary enzymes are not derived by glomerular filtration. The lack of coordinacy with lactate dehydrogenase suggests they are not derived from exfoliated cells. by analogy with experimental animals, they may be derived from lysosomes extruded into the lumen of the proximal tubule by epithelial cells. There is considerable variation among a population of 125 healthy adult subjects for total enzyme excretion. Both total enzyme excretion and coordinacy ratios are log-normally distributed, suggesting that they are the resultants of many factors, each of which has a relative, or proportional, effect on enzyme excretion. About one-half the population variation resides in a process common to the excretion of all four enzymes (possibly the lysosome extrusion pathway), and about one-half resides in factors affecting each enzyme independently.

Life satisfaction among black urban elderly

Previous research in white aged populations often has been derived from disengagement, activity, or personality theories. The relevance, however, of any of these conceptual frameworks to black aged is problematic because of their development in white samples and the lack of empirical data documenting their applicability to non-whites. The lack of systematic empirical research on black aged, and particularly, on the determinants of life satisfaction, provided the major impetus for the present study. Interview schedules were individually administered to 102 non-institutionalized retired men and women residing in a large urban area. A multiple regression analysis revealed a number of factors related to life satisfaction. The results are supportive of previous studies in white samples but are sufficiently distinct to raise questions regarding the applicability of these prior findings to black aged.

Personality characteristics of alcoholics and drug addicts in a merged treatment program

Groups of alcoholics and drug addicts in a mixed inpatient treatment facility were compared on personality characteristics by sex, age and type of drug. Sex and drug type showed few significant differences; however, age, regardless of drug or sex, proved to be significant on many personality variables.

Cholera toxoid boosts serum Escherichia coli antitoxin in humans

Sera from individuals vaccinated with a cholera toxoid were tested to determine if sera with significant titers of cholera antitoxin could neutralize Escherichia coli thermolabile enterotoxin. Individuals who responded to immunization with significant increases in serum cholera antitoxin titers also showed increases in serum E. coli enterotoxin-neutralizing capacity. These findings suggested the possibility that the cholera toxoid vaccine may be useful in preventing disease caused by E. coli.