Protection by verapamil of mitochondrial glutathione equilibrium and phospholipid changes during reperfusion of ischemic canine myocardium

Pretreatment of the ischemic myocardium with verapamil protects against mitochondrial respiratory depression observed during ischemic arrest as well as during reperfusion. Since ischemic mitochondrial function appears not to be altered further by reperfusion, the purpose of this study is to identify a biochemical event affecting mitochondria that is specifically associated with reperfusion injury. It has been proposed that increased cellular Ca2+ influx and oxygen toxicity may result from reintroduction of coronary flow. Increased cytosolic Ca2+ is transmitted to the mitochondria with subsequent activation of Ca2+-dependent events, including phospholipase A2. Net production of lysophospholipids (and loss of total diacylphospholipids from the mitochondria) will proceed when reacylation mechanisms are inhibited. Since acyl-CoA:lysophospholipid acyltransferase is a sulfhydryl-sensitive enzyme and since increased activity of glutathione peroxidase shifts the levels of the mitochondrial sulfhydryl buffer, glutathione, towards oxidation, levels of glutathione and its oxidation state were measured during reperfusion in the absence or presence of verapamil pretreatment. Ischemia lowers total glutathione and reduces the redox ratio (reduced glutathione: oxidized glutathione) by 85%. Reperfusion partially returns the redox ratio to control by causing oxidized glutathione to disappear from the matrix. Verapamil maintains both the concentration and the redox potential of glutathione at control levels. Concomitant with alterations in reduced glutathione:oxidized glutathione is a decrease in ischemic mitochondrial phospholipid content. During reperfusion, phosphatidylethanolamine and its major constituent fatty acids (C 18:0 and C 20:4) are specifically lost from the mitochondrial membrane. Accompanying the significant loss of arachidonic acid during reperfusion is the decreased content of 11-OH, 12-OH, and 15-OH arachidonate. These lipid peroxidation products are not increased in ischemia. It is proposed that oxidation of matrix glutathione to glutathione disulfide during ischemia results in formation of glutathione-protein mixed disulfides and inhibition of sulfhydryl-sensitive proteins, including acyl-CoA lysophosphatide acyltransferase. Thus, metabolic events occurring within the ischemic period set the stage for prolonged dysfunction during reperfusion.

The heterogeneity of the non-aggregating proteoglycans of the human intervertebral disc

Non-aggregating proteoglycans of differing average hydrodynamic volumes were prepared from nuclei pulposi and anuli fibrosi of three human lumbar spines and characterized by biochemical and immunochemical analyses. The hexose-to-hexuronate and protein-to-hexuronate ratios increased with decreasing hydrodynamic volume. Analysis by composite agarose/polyacrylamide-gel electrophoresis has demonstrated two aggregating subpopulations [McDevitt, Jahnke & Green (1982) Trans. Annu. Meet. Orthop. Res. Soc. 7, 50]. In the present study, electrophoresis of the non-aggregating pools has shown three additional subpopulations, here named bands III, IV and V. The two smallest proteoglycan pools from each tissue contained two and three components respectively. These components were isolated by preparative electrophoresis and analysed. Band III was a proteoglycan richer in keratan sulphate than in chondroitin sulphate; band IV was a proteoglycan richer in chondroitin sulphate than in keratan sulphate; band V contained only chondroitin sulphate. Unsaturated disaccharides prepared from the chondroitin sulphate of all bands were predominantly 6-sulphated, with only 5-15% 4-sulphated. The molecular masses of the chondroitin sulphate and keratan sulphate did not differ between the bands. The amino acid composition of band III differed from that of band IV. Thus three distinct subpopulations of non-aggregating proteoglycan were demonstrated in the human intervertebral disc.

Liquid-chromatographic determination of 4-hydroxyproline in urine

In this method for 4-hydroxyproline in urine, hydroxyproline is derivatized with 4-chloro-7-nitrobenzofurazan, with subsequent estimation by reversed-phase "high-performance" liquid chromatography. The ranges for excretion of free and total hydroxyproline while the subjects were ingesting unrestricted diets were 2-29 and 122-374 mumol/24 h (n = 21), respectively, with no significant sex-related difference. A comparison with results by colorimetry indicated no significant differences: mean (n = 18) concentrations (mumol/L) of hydroxyproline in urine were 180 (SD 149) by the present method, 163 (SD 166) by colorimetry. For protein hydrolysate the respective values were 5.9 (SD 2.7) and 6.7 (SD 2.9).

Liquid-chromatographic determination of 4-hydroxyproline in urine

In this method for 4-hydroxyproline in urine, hydroxyproline is derivatized with 4-chloro-7-nitrobenzofurazan, with subsequent estimation by reversed-phase "high-performance" liquid chromatography. The ranges for excretion of free and total hydroxyproline while the subjects were ingesting unrestricted diets were 2-29 and 122-374 mumol/24 h (n = 21), respectively, with no significant sex-related difference. A comparison with results by colorimetry indicated no significant differences: mean (n = 18) concentrations (mumol/L) of hydroxyproline in urine were 180 (SD 149) by the present method, 163 (SD 166) by colorimetry. For protein hydrolysate the respective values were 5.9 (SD 2.7) and 6.7 (SD 2.9).

Rabbit photoreceptor outer segments contain high levels of docosapentaenoic acid

Docosapentaenoic acid (22:5 omega 6), a minor constituent (less than 4%) of photoreceptor outer segment membranes in all vertebrate species examined to date, comprises 23% of the fatty acids in total lipids from rabbit outer segment membranes. This fatty acid is a significant constituent of each of the three major phospholipid classes in these membranes. The levels of docosahexaenoic acid (22:6 omega 3), the major polyunsaturated fatty acid of most other vertebrate outer segments, was 20%. The sum of 22:5 omega 6 and 22:6 omega 3 in rabbit outer segment membrane lipids is similar to the amount of 22:6 omega 3 usually found in membranes from other vertebrate species.

Quantitation of lipid peroxidation products by gas chromatography-mass spectrometry

A method for the quantitation of lipid peroxidation products in total hepatic lipid has been developed. Lipid extracts are reduced and subsequently transmethylated with sodium methoxide. The hydroxy fatty acid methyl esters are isolated by silicic acid chromatography and derivatized to their trimethylsilyl ethers prior to analysis by gas chromatography-mass spectrometry. Three isomers, 11-, 12-, and 15-hydroxyeicosatetraenoic acid (HETE), are quantitated using selected ion monitoring techniques relative to the internal standard, methyl 15-hydroxyarachidate. In mice treated with carbon tetrachloride (2 ml/kg), the HETE levels in total hepatic lipid were 20-fold greater than those found in control animals. HETE levels were also elevated (5- to 10-fold) in hepatic lipid from rats treated with the same dose of carbon tetrachloride. Studies on subcellular fractions with this methodology show that these lipid peroxidation products are 5- to 6-fold higher in hepatic plasma membrane vesicles isolated from rats treated with carbon tetrachloride when compared with those isolated from control animals.

Oxidant stress and hepatic necrosis in rats treated with diquat

Although diquat produces massive oxidant stress in both Fischer and Sprague-Dawley rats, the Fischer rats sustain hepatic necrosis and the Sprague-Dawley rats do not. A previous example of probable hepatic necrosis produced by an oxidant stress-generating compound was demonstrated in animals in which glutathione peroxidase activity had been decreased by a dietary deficiency of selenium. In the present study the susceptible Fischer rats had hepatic peroxidase activities equal to the resistant Sprague-Dawley rats. Hepatotoxic doses of diquat did not diminish hepatic glutathione peroxidase or reductase activities or hepatic content of ascorbic acid, NADPH or protein sulfhydryls. Hepatic nonprotein sulfhydryls were decreased by 50% but recovered to control values by 6 h. Biliary excretion of oxidized glutathione in the Fischer rat after administration of diquat was 4 times that observed after administration in Sprague-Dawley rats. The diquat-induced peroxidation of hepatic lipids was indicated by small increases in the 11-, 12-, and 15-hydroxyeicosatetraenoic acids, as quantitated by a new gas chromatography-mass spectrometry assay. Thus, acute lethal injury caused by redox cycling compounds that generate reactive oxygen species does not exhibit a number of the biochemical alterations in vivo that occur with cell death produced by similar compounds in isolated hepatocyte systems.

Effects of N-acetylcysteine on the disposition and metabolism of acetaminophen in mice

N-acetylcysteine is the drug of choice for the treatment of acetaminophen poisoning, yet the mechanism of protection in vivo is unknown. Prevention of liver injury could result from decreased production of the toxic intermediate(s), from increased capacity to detoxify the toxic intermediate(s) or from increased ability of the tissue to withstand or even repair the molecular damage caused by the toxic species. Treatment of mice with N-acetylcysteine (1200 mg/kg p.o.) was found to prevent the hepatic damage caused by 1000 mg/kg p.o. of acetaminophen. Possible mechanisms for this hepatoprotective effect were examined by measurement at different time points of acetaminophen and its metabolites in plasma, urine, bile and whole-body homogenates and by evaluation of the changes in these parameters caused by treatment with N-acetylcysteine. A high-pressure liquid chromatographic method was developed to measure the majority urinary metabolites of acetaminophen and was validated by desorption chemical ionization mass spectral analysis of individual metabolites. Minimal differences in the concentration of unchanged acetaminophen and metabolites in whole-body homogenates at 4, 6 and 24 hr postdose were noted for N-acetylcysteine-treated vs. vehicle-treated mice. These results are incompatible with a decreased formation of the toxic species secondary to delayed acetaminophen absorption from the gastrointestinal tract or with an increased clearance of acetaminophen via nontoxic pathways such as sulfation as plausible mechanisms for the observed hepatoprotection.(ABSTRACT TRUNCATED AT 250 WORDS)

Metabolic fate of (E)-5-(2-bromovinyl)-2'-deoxyuridine in herpes simplex virus- and mock-infected cells

(E)-5-(2-Bromovinyl)-2'-deoxyuridine is a potent antiherpes compound with far better activity against herpes simplex virus type 1 than type 2. To understand the role of drug metabolism in this differential antiviral activity, we examined the metabolic fate of this drug in virus-infected and mock-infected Vero cells by high-pressure liquid chromatography. After 8 h of incubation in which cells were exposed to 10 micrograms of the drug per ml, 63 pmol/10(6) cells of the parent compound was detected in acid-soluble extracts of mock-infected cells. Herpes simplex virus-infected cells, however, incorporated or metabolized, or both, up to 11,310 pmol/10(6) cells. Type 1-infected cells metabolized the drug to the triphosphate where as many as 5,565 pmol/10(6) cells were detected. In contrast, three strains of type 2-infected cells metabolized the drug to the monophosphorylated nucleotide and no further. The amount of drug getting into the cells was virus strain and inoculum dependent. These studies indicate that poor substrate acceptance of (E)-5-(2-bromovinyl)-2'-deoxyuridine monophosphate by herpes simplex virus type 2-specified thymidylate kinase is an important factor in situ in infected cells, preventing anabolism of the parent compound to its active triphosphorylated form. This may account for its type specificity.

Free radicals in vivo. Covalent binding to lipids

As one means of determining the extent to which free radical metabolites are involved in the interaction of hepatotoxic drugs with target tissues, we have measured the covalent binding to hepatic lipids of carbon tetrachloride, acetaminophen, 2-furamide, furosemide, dimethylnitrosamine, and bromobenzene. Transesterification of the Folch lipid fraction was required to distinguish radioactive label present but not covalently bound to alkyl residues through radical addition or combination reactions. Although all hepatotoxins were covalently bound to hepatic protein in the range of 1-2 nmoles/mg, thereby confirming tissue alkylation by reactive metabolites under the present experimental conditions, only carbon tetrachloride gave significant covalent binding to the alkyl residues of hepatic lipids (4.34 nmoles/mg). Thus, although these data further support the already well-documented role of a free radical in the reaction of carbon tetrachloride with target tissue molecules, none of the other hepatotoxins gave similar indications. Dimethylnitrosamine did give significant covalent binding to lipids, but the removal of the binding by transesterification indicates that the binding apparently resulted from electrophilic attack on nucleophilic centers present in phospholipids rather than from radical attack on electroneutral alkyl residues of the lipids.

Biliary excretion of glutathione and glutathione disulfide in the rat. Regulation and response to oxidative stress

Regulation of the biliary excretion of reduced glutathione (GSH) and glutathione disulfide (GSSG) and responses to selected model toxins were examined in male Sprague-Dawley rats. In control and phenobarbital-pretreated rats in which the intrahepatic concentration of GSH was modulated by the administration of diethyl maleate or acetaminophen, the biliary concentration of GSH was consistently lower than, but directly proportional to, the intrahepatic concentration of GSH. Furthermore, increments in bile flow produced by the infusion of sulfobromophthalein (BSP)-glutathione were associated with proportional increases in the biliary excretion of GSH, suggesting that GSH passes into bile passively along a concentration gradient. In contrast, GSSG appears to be secreted into bile against a steep concentration gradient. An increased hepatic production and biliary excretion of GSSG resulted from the administration of t-butyl hydroperoxide. Measurement of biliary GSSG and BSP during a constant infusion of the GSH adduct of BSP indicated that GSSG shares a common excretory mechanism with GSH adducts. Diquat, nitrofurantoin, and paraquat also markedly stimulated the biliary excretion of GSSG. On a molar basis, these compounds generated much more GSSG than a direct substrate for glutathione peroxidase such as t-butyl hydroperoxide, indicating that the compounds undergo redox-cycling with concomitant production of hydrogen peroxide. Aminopyrine (0.8 mmol/kg) also significantly increased biliary GSSG. This increase, however, was associated with a proportional increase in bile flow and in the biliary excretion of GSH such that the GSSG/GSH ratio in bile did not change. Acetaminophen and chloroform, two compounds generating electrophilic metabolites that deplete intrahepatic GSH, led to a progressive decrease in the biliary excretion of GSH and GSSG. Furosemide and dimethylnitrosamine, the electrophilic metabolites of which do not deplete hepatic GSH, minimally altered biliary GSH and GSSG. Similarly, carbon tetrachloride and iproniazid, which yield organic radical metabolites that can peroxidize membrane lipids, did not increase the biliary excretion of GSSG. This finding indicates that membrane-bound lipid hydroperoxides may not be good substrates for glutathione peroxidases. The measurement of the biliary excretion of GSSG and of the GSSG/GSH ratio in bile is a sensitive index of oxidative stress in vivo and thus complements other in vivo parameters for the study of reactive intermediates of xenobiotics such as the determination of covalent binding, the formation of lipid hydroxy acids, and the depletion of intracellular GSH.

High-performance liquid chromatography and gas chromatography-mass spectrometry determination of specific lipid peroxidation products in vivo

Peroxidation of membrane lipids has been implicated in the toxicity of reactive oxygen intermediates and of several hepatotoxins, but the specific products of this peroxidation in vivo have not been chemically identified. A method for the isolation, identification, and quantitation of specific lipid hydroperoxy and hydroxy acids formed in vivo has been developed. Hydroxylated derivatives of linoleic, arachidonic, and docosahexaenoic acids formed in mouse liver phosphatidylcholines following carbon tetrachloride administration were isolated by high-pressure liquid chromatography and identified as the trimethylsilyl ether methyl ester derivatives by gas chromatography-mass spectrometry. This methodology should be important for the investigation of the role of lipid peroxidation in a variety of normal physiologic and pathologic processes.

The effect of frontal EMG biofeedback training on the behavior of children with activity-level problems

N = 1 withdrawal designs were employed with three children evidencing activity-level problems. Tutoring sessions occurred daily over a 2 1/2-month period. Each child was reinforced for decreasing frontalis muscle tension during auditory feedback while working arithmetic problems. Feedback was faded while tension reduction reinforcement was maintained. These procedures were repeated with reinforcement for increasing, rather than decreasing, muscle tension. Frontal EMG level, percent time on task, and motoric activity rate were obtained during sessions. Parent ratings of problem behavior in the home were recorded daily. Biofeedback with reinforcement was effective in both raising and lowering muscle tension. Effects were maintained by reinforcement. Results suggest a direct relationship between tension and activity levels. Academic performance and problem behavior improved significantly with reductions in EMG activity, although individual exceptions to these findings were present. Results lend support to the efficacy of frontal EMG biofeedback training in reducing activity, increasing attention to an academic task, and reducing problem behaviors.

Treatment of aggressive behavior: the effect of EMG response discrimination biofeedback training

This N of 1 study utilizes a withdrawal design with aggressive responses of a 27-year-old male exhibiting autistic behavior. The frequency of physical and verbal aggressive responses was decreased by reinforcing attempts to relax (utilizing EMG biofeedback) when discriminative stimuli for aggressive behavior were present.

Effects of combined nitrogen on anapleurotic carbon assimilation and bleeding sap composition in Phaseolus vulgaris L

Dwarf french beans, Phaseolus vulgaris L., were grown with or without inoculation with rhizobia (strain 3644), and with or without a combined nitrogen source (nitrate or ammonium ions). The distribution of radioactivity into products of dark (14)CO2 assimilation was studied in roots or nodules from these plants. A detailed study was also made of the distribution and rates of excretion of nitrogen in xylem bleeding sap in 28 day old plants grown on the various sources of nitrogen. Whereas detached nodules accumulated radioactive glycine, serine and glutamate when incubated with (14)CO2, bleeding sap from plants root fed (14)CO2 contained low levels of radioactivity in these compounds but higher levels in allantoin. Chemical analysis showed allantoin to be the major compound transported in the xylem of nodulated plants, whether or not they were fed on combined nitrogen. In contrast uninoculated plants accumulated mainly amino acids in the bleeding sap, the amount and chemical composition of which depended on the combined nitrogen source.

Treatment of handwriting problems utilizing EMG biofeedback training

The effects of EMG biofeedback training on cursive handwriting were investigated for 4 girls and 5 boys in Grade 4. A significant reduction in EMG between the first baseline session and the last training session was obtained. Four of 5 characteristics of handwriting improved significantly. The need for carefully designed research comparing EMG biofeedback training and relaxation training was indicated. A self-control factor in handwriting was hypothesized.

Effects of relaxation training on cursive handwriting of fourth grade students

A relaxation method of handwriting improvement was examined. The experimental and no-treatment control groups were composed of 10 students receiving a poor rating on handwriting characteristics and the normal control group of 10 was composed of students receiving average ratings. All three groups received nine trials of writing. Only the experimental group received relaxation training during each trial. The handwriting of the experimental group improved significantly while that of the no-treatment control group remained the same. Although the handwriting of the normal control group also improved significantly, at posttest they were no longer significantly different from the experimental group.

Licorice raises urinary cortisol in man

The finding that urine cortisol excretion was increased in patients with hypokalaemic hypertension induced by licorice addiction led to this study on the effect of licorice in normal subjects. Thirteen normal volunteers ate either 100 or 200 g licorice for 1-4 weeks and assessment of pituitary-adrenal function was made before, during, and 1 week after cessation of licorice ingestion. Urine cortisol excretion more than doubled in 10 of 13 subjects (mean, 33.8 +/- 15.6 SD before and 83.3 +/- 56 SD micrograms/24 h at 1 week after commencing licorice) and excretion rates similar to those observed in Cushing's syndrome were seen in 7 subjects (range, 91-226, compared to normal range of 11-82 micrograms/24 h). Urine cortisol excretion remained significantly elevated (P less than 0.01) above control levels for at least 1 week after licorice was withdrawn. Despite these increases, urinary steroid metabolite (tetrahydrocortisol, tetrahydrocortisone, tetrahydro-11-deoxycortisol, 17-ketogenicsteroids, and 17-ketosteroids) excretion was not affected, plasma cortisol and ACTH values were unchanged, and normal 0800-1600-h diurnal variation of plasma cortisol was maintained. The direct intraadrenal infusion of the active mineralocorticoid component of licorice, glycyrrhetinic acid, in two sheep with autotransplanted adrenal glands failed to stimulate cortisol secretion acutely. It is concluded from these studies that the licorice-induced changes in cortisol excretion are not a result of adrenocoritcal stimulation but more likely represent a change in the renal handling of cortisol.

One session of flooding as treatment for conditioned avoidance responding in humans: effect of individualization of treatment duration

An avoidance response was conditioned to three stimuli (tone, vibrator, and light) presented in serial order. Following conditioning, each group of subjects underwent a different treatment procedure. Group 1 received a completely individualized flooding procedure distributed over multiple trials. Duration of the conditioned stimulus presentations was individualized by making them contingent upon termination of conditioned suppression, and duration of the treatment session by termination of conditioned avoidance. The Group 2 flooding procedure was completely non-individualized, massed into one trial and yoked to Group 1 to control for the amount of exposure to each of the conditioned stimuli and the duration of treatment sessions. Group 3 experienced non-individualized duration of treatment, individualized conditioned stimulus presentations distributed over trials and controlled for the duration of the treatment session and the distribution of trials. Analysis indicated that individualized duration of the flooding session utilizing a measure of anxiety dissipation significantly hastened the extinction of avoidance responses. Implications for the effective practice of implosive therapy were discussed.

Effect of eating liquorice on the renin-angiotensin aldosterone axis in normal subjects

The effect of confectionery liquorice on electrolyte status and the renin-angiotensin-aldosterone (RAA) axis was studied in 14 healthy volunteers. They ate liquorice in daily doses of 100 g or 200 g (equivalent to 0-7-1-4 g glycyrrhizinic acid) for one to four weeks. Plasma potassium concentrations fell by over 0-3 mmol/l in 11 people, including four who had to be withdrawn from the study because of hypokalaemia. One or more values of the RAA axis, especially plasma renin activity and urinary aldosterone concentrations, were considerably depressed in all subjects. These results show that potentially serious metabolic effects may occur in some people who eat modest amounts of liquorice daily for less than a week.

Effect of potassium-sparing diuretics on the renin-angiotensin-aldosterone system and potassium retention in heart failure

The renin-angiotensin-aldosterone system and electrolyte levels in 11 patients with heart failure controlled on digoxin and frusemide were investigated after separate periods of Slow K, spironolactone, and amiloride therapy. When spironolactone or amiloride replaced Slow K, distinct parallel increments in the levels of renin, angiotensin II, and aldosterone resulted. Though plasma potassium was generally higher after spironolactone and amiloride than after Slow K, exchangeable potassium was similar with the three regimens. There was no significant relation between plasma potassium and concurrent exchangeable potassium.

Primary aldosteronism. A study in contrasts

Two patient with primary aldosteronism, one with a solitary adrenal adenoma and the other with bilateral nodular hyperplasia, are described. Both patients showed the classic features of primary aldosteronism in electrolyte and hormone patterns, but there were important differences in the biochemistry of their excised adrenal tissue. In addition, the injection of plasma from the patient with bilateral adrenal hyperplasia into the sheep's transplanted adrenal gland elicited a definite aldosterone secretory response, but there was no aldosterone response to the injection of plasma from the patient with a solitary adrenal adenoma. The findings support the hypothesis that an extra-adrenal stimulus may contribute to the pathogenesis of bilateral adrenal hyperplasia.

Aldosterone and its regulation during diuresis in patients with gross congestive heart failure

1. Plasma aldosterone concentration and urine aldosterone excretion were studied before and during sustained diuresis in six patients with gross congestive heart failure, under conditions of fixed sodium and potassium intake and strict control of body posture. Simultaneous measurements of plasma renin activity, plasma corticotrophin and electrolytes were made to assess the relative importance of these factors in the regulation of aldosterone secretion before and during treatment of congestive heart failure.

2. During the pre-treatment phase aldosterone levels were normal or raised, but with acute diuresis fell to unmeasurable levels in most cases. This depression in aldosterone tended to coincide with peak natriuresis. Later in the diuretic phase aldosterone values increased often to very high levels as dry body weight was attained.

3. With few exceptions plasma renin activity fluctuations paralleled those of plasma aldosterone, whereas corticotrophin levels remained largely within normal limits and plasma electrolytes did not change appreciably.

4. The results suggest that the renin—angiotensin system is the important regulator of aldosterone secretion before and during diuretic treatment in patients with gross congestive heart failure.

A comparative study of some commercially available tests for rheumatoid factor

Seven commercially available screening tests for rheumatoid factor and two quantitative tests have been compared with the standard Rose-Waaler test in a series of 477 sera from patients with various joint diseases. Markedly different results were obtained, and on the basis of our findings suggestions are made as to what we consider to be the most satisfactory currently available tests.

Cyclical changes in the islets of Langerhans in the rat pancreas

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