Aldehyde dehydrogenase activity as the rate-limiting factor for acetaldehyde metabolism in rat liver

The velocity of acetaldehyde metabolism in rat liver may be governed either by the rate of regeneration of NAD from NADH through the electron transport system or by the activity of aldehyde dehydrogenase (ALDH). Measurements of oxygen consumption revealed that the electron transport system was capable of reoxidizing ALDH-generated NADH much faster than it was produced and hence was not rate-limiting for aldehyde metabolism. To confirm that ALDH activity was the rate-limiting factor, low-Km ALDH in slices or intact mitochondria was partially inhibited by treatment with cyanamide and the rate of acetaldehyde metabolism measured. Any inhibition of low-Km ALDH resulted in a decreased rate of acetaldehyde metabolism, indicating that no excess of low-Km ALDH existed. Approximately 40% of the metabolism of 200 microM acetaldehyde in slices was not catalyzed by low-Km ALDH. Fifteen of this 40% was catalyzed by high-Km ALDH. A possible contribution by aldehyde oxidase was ruled out through the use of a competitive inhibitor, quinacrine. Acetaldehyde binding to cytosolic proteins may account for the remainder. By measuring acetaldehyde accumulation during ethanol metabolism, it was also established that low-Km ALDH activity was rate-limiting for acetaldehyde oxidation during concomitant ethanol oxidation.

Use of cyanamide to determine localization of acetaldehyde metabolism in rat liver

Various techniques have been employed previously to show that acetaldehyde is primarily oxidized in the mitochondrial matrix of rat liver. In this study, a new approach was tested. Mitochondrial low-Km aldehyde dehydrogenase (ALDH) was partially inactivated and the effect on acetaldehyde oxidation measured. Cyanamide was chosen as the ALDH inhibitor. An enzymatic activation of cyanamide, probably by catalase, was necessary for the drug to inhibit ALDH activity. The level of remaining ALDH activity after cyanamide treatment was correlated with the ability of either rat liver mitochondria or liver slices to oxidize acetaldehyde. Any inhibition of ALDH resulted in a decreased rate of acetaldehyde oxidation, indicating that there is no excess of ALDH in the cell above what is needed to oxidize acetaldehyde. Approximately 15% of the acetaldehyde disappearance at 200 microM was catalyzed by high-Km ALDH, and nearly 30% of the acetaldehyde was lost through binding to cytosolic proteins.

Is there a relationship between eating disorder and affective disorder? New evidence from sleep recordings

There is evidence that patients with anorexia nervosa (particularly those who also have bulimia) and patients with affective disorder share many features. The authors present sleep polygraph data from 20 young women with anorexia nervosa (17 also bulimic) and 10 age-matched normal women. Their urinary free cortisol levels were determined, and the subjects with eating disorders were also rated for depression. The findings suggest the existence of a subgroup of patients who show sleep abnormalities, in addition to clinical and possibly endocrine abnormalities, that indicate concurrent affective disorder. The authors present several models that could account for this relationship.

Application of metabolic profiling to study the effects of ethanol on metabolism in rats

Rat urine was analyzed by both gas chromatography and a combination of gas chromatography/mass spectroscopy in an attempt to apply the technique of metabolic profiling to determine if ethanol consumption produced an alteration in acid excretion products. Rats were fed a liquid diet for seven days then fed ethanol in the same diet. The 24 hr urine for the last day of control and the first day of ethanol differed greatly with respect to four compounds. These were an increase in threonic, glucuronic and an undetermined acid and a decrease in pyroglutamic acid. The biological basis for the alterations was not investigated. Glucuronic acid forms conjugates with many compounds. Possibly an acute dose of ethanol may alter the removal of some compounds from the liver.

Distribution and properties of aldehyde dehydrogenase in regions of rat brain

NAD-dependent aldehyde dehydrogenases (EC 1.2.1.3) were isolated from various subcellular organelles as well as from different regions of rat brain. The mitochondrial, microsomal, and cytosolic fractions were found to contain 40%, 28%, and 12%, respectively, of the total aldehyde dehydrogenase (5.28 +/- 0.44 nmol NADH/min/g tissue) found in rat brain homogenate when assayed with 70 muM propionaldehyde at pH 7.5. The total activity increased to 17.3 +/- 2.7 nmol NADH/min/g tissue when assayed with 5 mM propionaldehyde. Under these conditions the three organelles contained 49%, 23%, and 9%, respectively, of the activity. The enzyme isolated from cytosol possessed the lowest Km. The molecular weight of the enzyme isolated from all three subcellular organelles was approximately 100,000. Four activity bands were found by electrophoresis of crude homogenates, isolated mitochondria, or microsomes on cellulose acetate strips. Cytosol possessed just two of the forms. The total activity was essentially the same in homogenates obtained from cortex, subcortex, pons-medulla, or cerebellum. Further, the enzyme had the same molecular distribution and total activity in each of these four brain regions. Disulfiram was found to be an in vivo and in vitro inhibitor of the enzymes obtained from these brain regions. Mercaptoethanol, required for the stability of the enzyme, reversed the inhibition produced by disulfiram. The effect was greater for enzyme isolated from cytosol than from mitochondria. Calculations led to the prediction that aldehydes such as acetaldehyde are oxidized in cytosol.

Ischemic pseudomembranous colitis with perforation due to polyarteritis nodosa

Polyarteritis nodosa is a multisystem disease that involves the gastrointestinal tract in more than 50% of patients at some time during its course. Clinically apparent ischemic disease of the small bowel is the frequent site of involvement. The colon is less commonly involved, particularly as the initial presentation. We present a patient with polyarteritis nodosa noteworthy for prolonged nonbloody diarrhea, ischemic colitis with perforation, and pseudomembrane formation who had histological documentation of polyarteritis nodosa.

What the future holds for psychosomatic medicine

In the recent past, the questions that face a comprehensive psychosomatic medicine have been defined. These questions refer to the context in which disease begins, the timing of the onset of the disease, the role of previous social experience in predisposing to disease, and the choice of the particular disease. It is suggested that a study of bereavement may be paradigmatic in answering these four questions: Bereavement has been cited as a factor in a large variety of disease. However, bereavement may produce discriminated responses of grief; helplessness, hopelessness, and giving-up; and pathological mourning. Pathological mourning in turn may be associated with autoimmune disease. There is evidence that separation and bereavement produces changes in immune function but there is as yet no evidence that it produces distortions of the immune process. There are many factors that affect the timing of disease onset, including maturational ones. Many social experiences have been shown to alter behavior and bodily function and predispose to disease. The question of the choice of disease is determined not only by the effects of bereavement and early experiences, and age, but also by a multiplicity of predisposing ones some of which have been specified.

An integrative model of health, illness, and disease

Health has traditionally been viewed in this country as the opposite of illness, even though what constitutes "health" is usually not clearly defined. This article highlights the complexity of the factors that influence health, probes the relationship between illness and disease, and explores the possibilities of establishing an integrated view of health, illness, and disease.

Effect of ethanol on synaptosomal (Na+ + K+)-ATPase in control and ethanol-dependent rats

Rats were made dependent upon ethanol by feeding them liquid diets containing ethanol. Synaptosomal plasma membranes (SPM) were isolated from cerebral cortex and midbrain regions of isocaloric-fed control and ethanol-dependent rats. No major alcohol-induced alteration in in vitro (Na+ + K+)-ATPase activity was found in SPM of either brain area. At 37 degrees C, ethanol (0.10 to 0.98 M) added to incubations caused a dose-dependent inhibition of (Na+ + K+)-ATPase activity. The degree of inhibition found was independent of the diet administered or whether ethanol was present in the diet. At temperatures between 14 and 22 degrees C, 0.48 M ethanol caused a temperature-dependent decrease in activity. Arrhenius plots for SPM (Na+ + K+)-ATPase showed that in control and ethanol-dependent rats fed the Lieber de Carli diet, 0.48 M ethanol did not alter the transition temperature of this enzyme. Activation energies both above and below the transition temperature were decreased by the addition of ethanol to incubations. These results indicate that (Na+ + K+)-ATPase, a membrane-bound enzyme that is sensitive to its lipid environment and to the presence of ethanol, is not altered by the chronic administration of ethanol to rats.

Oxidation of acetaldehyde and presence of aldehyde dehydrogenase in rat erythrocytes

Rat liver erythrocytes were found to oxidize acetaldehyde at 7 nmoles/min/ml blood at 37 degrees C. This is less than 1% the rate that occurs in liver. An aldehyde dehydrogenase was isolated from erythrocytes, but was not purified. The enzyme had a Km of 170 microM toward acetaldehyde at pH 7.4. The enzyme, which could oxidize both aliphatic and aromatic aldehydes, was more active at pH 9 than at 7. Disulfiram proved to be both an in vivo and in vitro inhibitor of the enzyme. Due to the low total capacity of the erythrocytes to metabolize acetaldehyde, it is doubtful they perform any important role in ethanol metabolism.

Effects of magnesium and calcium on mitochondrial and cytosolic liver aldehyde dehydrogenases

The effects of Mg2+ and Ca2+ ions on the activities of mitochondrial and cytosolic aldehyde dehydrogenases isolated from horse, rat, and beef livers were investigated in 0.1 M sodium phosphate, pH 7.5, at 25 degrees C. As with the Mg2+-enhancement of the horse liver mitochondrial enzyme [17], Mg2+-activation was observed for the mitochondrial enzymes from rat and beef. The cytosolic enzymes from horse, rat, and beef livers were inhibited in the presence of Mg2+ ions. The effects of Ca2+ ions on the activity were essentially the same as those observed in the presence of Mg2+ ions; the mitochondrial isozymes were activated while the cytosolic isozymes were inhibited. The fact that only the activity of mitochondrial forms of mammalian liver aldehyde dehydrogenase was enhanced by Ca2+ or Mg2+ ions may be related to the in vivo regulation of aldehyde metabolism, a presumed mitochondrial event.

Nonobesity at the time of mastectomy is highly predictive of 10-year disease-free survival in women with breast cancer

25 unselected women with operable breast cancer were followed after radical mastectomy until they died of recurrent cancer (non-survivors), or for 10 years if there was no recurrence (survivors): all the women still alive at 10 years were clinically and radiographically disease-free. Survivors and non-survivors were compared with respect to premastectomy height, and deviation from ideal weight. There were 16 women in the survivor group; at the time of mastectomy, they averaged 11% above ideal weight and only 4 of them (25%) were obese (20% or more above ideal weight). There were 9 women in the non-survival group; they averaged 51% above ideal weight at the time of mastectomy and all of them were obese, as defined. The intergroup difference in mean deviation from ideal weight was very highly significant (P less than 0.0001). Of the 13 women who were obese at mastectomy, only 4 (31%) became survivors, while 100% of the 12 women who were non-obese at mastectomy became survivors; the difference in percent survival was very highly significant (P less than 0.005). Separate evaluation of the roles of height and weight showed that height was not a factor and weight accounted entirely for the observed differences. It appears that maintenance of nonobesity may be a more effective way of decreasing mortality from breast cancer than any other measure proposed to date.

Genetic basis for the polymorphism of rat liver cytosolic aldehyde dehydrogenase

Liver aldehyde dehydrogenase (ALDH), the enzyme involved in the oxidation of aldehydes such as acetaldehyde derived from ethanol, exists in multiple forms in most mammals. Up to five separable forms have been identified from the cytosolic fraction of Wistar rat liver. We investigated genetic basis of a particular set of three enzyme forms by selective breeding and analysis of electrophoretic patterns of liver ALDH by isoelectric focusing. The forms of liver ALDH investigated were at pI 5.8 or 6.2 or a triple form with enzymes at pI 5.8, 6.0, and 6.2. There are two alleles found at the ALDH locus which encode in homozygotes for one of two electrophoretically separable ALDH forms. A rat heterozygous at the locus forms both ALDH types plus a hybrid. The alleles are expressed codominantly, found at an autosomal locus, and remain constant postpartum. The activities associated with the triplet enzyme form were statistically indistinguishable from a 1:2:1 ratio. This suggests that the enzymes hybridize to form a set of dimers or tetramers of the form A2, AB, B2, or A4, A2B2, B4, respectively.

Effects of pH on horse liver aldehyde dehydrogenase: alterations in metal ion activation, number of functioning active sites, and hydrolysis of the acyl intermediate

The reactivity of the mitochondrial (pI = 5) isoenzyme of horse liver aldehyde dehydrogenase was determined by studying the effects of pH on steady-state velocity, burst magnitude, and molecular weight of the enzyme in the absence and presence of Mg2+ ions. The Mg2+ ion activation of the steady-state velocity at pH 7.5 has been explained through a mechanism involving alteration of the tetrameric enzyme, functioning with half-of-the-sites reactivity, to a dimeric enzyme, functioning with all-of-the-sites reactivity [Takahashi, K., & Weiner, H. (1980) J. Biol. Chem. 255, 8206-8209]. With increasing pH, the tetrameric enzyme dissociated even in the absence of Mg2+ ions to the more active dimeric state. The pH-dependent dissociation was governed by proton release from a group with pK = 9.5. After correcting for the increased number of functioning active sites, determined from the pre-steady-state burst, we calculated that elevated pH also caused an increase in the velocity of the rate-limiting step, hydrolysis of the acyl-enzyme intermediate. This event was governed by the ionization of two groups, with pK = 7.2 and 9.5, respectively. If these groups are directly involved in the catalytic step, a mechanism involving histidine acting as a general base can be proposed for the former group. The latter group may be involved in a charge relay activation process which only occurs at elevated, nonphysiological pH. The importance of the latter is questionable, as there is only a 3-fold increase in Vmax when this group is involved in catalysis.

Increasing slowed operant responding of schizophrenics under a fixed-ratio schedule of reinforcement

Two procedures were evaluated in terms of their ability to modify the slowed responding of schizophrenics under an FR 40 schedule. FR 40 response rates increased when schizophrenics were instructed to earn a minimum number of reinforcements or to imitate the rate of responding of someone shown earning that minimum number of reinforcements. The greater increase in FR 40 responding occurred under the latter procedure.

The production rate of cortisol declines during recovery from anorexia nervosa

The plasma concentration of cortisol is elevated in many patients with anorexia nervosa. It has remained unclear whether this elevation of plasma cortisol level is due only to a slowing of the rate of cortisol metabolism or whether there is, as well, an increase in adrenal secretory activity in anorexia nervosa. We studied adrenocortical activity in 9 female patients and one male patient with anorexia nervosa before and during recovery. The 24-h mean level of plasma cortisol and the rate of urinary free cortisol excretion decreased during recovery, from 11.4 to 7.4 micrograms/dl and from 225 to 116 micrograms/day, respectively (P less than 0.005 and P less than 0.10, paired t test). These changes were associated with a significant decline in the rate of cortisol production from 24.3 to 17.9 mg/day as measured by radioisotope dilution (P less than 0.005). These results suggest that adrenal secretory activity is increased in anorexia nervosa and that the elevation of plasma cortisol level observed in this syndrome reflects not only a slowing of cortisol metabolism but also a rise in cortisol production.

Contributions of reinforcement schedule histories to our understanding of drug effects in human subjects

Like other reinforcing stimuli, drug effects may vary with the reinforcement history of an individual. Data are presented which demonstrate that histories contribute to individual differences in response to reinforcement contingencies and modification of maladaptive behavioral persistence. Possible relevance of these findings to an understanding of drug effects in humans is discussed.

Possible steady-state concentrations of tetrahydroisoquinolines in brain after the consumption of ethanol

Dopamine-derived tetrahydroisoquinolines such as salsolinol and tetrahydropapaveroline have been implicated in alcohol-related problems. Though their infusion into the brain can induce a rat to increase its alcohol consumption, it is not known whether the compounds actually form in vivo. Few investigators have been able to extract the compounds or their metabolites from tissue or urine. One notable exception is reported by Collins et al. (Science 206: 1184--1186; 1979), who found that alcoholics excrete 140 micrograms/24 h of O-methyl salsolinol and salsolinol. Using that value as the rate of salsolinol formation in brain, it was possible to estimate the steady-state concentration that could be expected to be found in brain. It was assumed that the rate of synthesis is equal to the rate of removal from tissue. Thus, the concentration is simply vf/kd, where vf is the rate of formation and kd is the rate constant for the disappearance from brain. It is necessary to estimate the concentration of dopamine and aldehyde in brain to determine the rate of formation. The realistic upper limits for salsolinol and tetrahydropapaveroline in brain are ca. 1 ng/g brain tissue. These values are below the level of detection commonly employed.

Nicotinamide adenine dinucleotide activation of the esterase reaction of horse liver aldehyde dehydrogenase

The esterase reaction catalyzed by horse liver aldehyde dehydrogenase is activated with NAD(H) by factors of 2 under a Vmax assay and of 6.8 at low ester concentrations (Feldman, R. I., & Weiner, H. (1972) J. Biol. Chem. 247, 267-272). Stopped-flow experiments suggested that an initial burst of 0.4 mol followed by a second burst of 1 mol of nitrophenol per mol of tetrameric enzyme occurred in the absence of NAD, while the magnitudes increased to 2 and 4 mol/mol of enzyme in its presence. If the enzyme was incubated for 1 min with NAD, the burst phase was 4 mol/mol of enzyme. Nonlinear Lineweaver--Burk plots were found in the absence and presence of NAD, but incubation with NAD for 1 min abolished the biphasic response. Mg2+ ions activate the dehydrogenase reaction of horse liver aldehyde dehydrogenase (Takahashi, K., & Weiner, H. (1980) J. Biol. Chem. 255, 8206-8209). The metal neither increased the esterase reaction nor affected the NAD activation. The rate-limiting step for the esterase reaction was thought to be the formation of an acyl intermediate, while that for the dehydrogenase reaction was deacylation (Weiner, H., Hu, J. H. J., & Sanny, C. G. (1976) J. Biol. Chem. 251, 3853-3855). Finding that a full burst exists for the esterase reaction in the presence of NAD shows that the deacylation step or product dissociation can become rate limiting. The major kinetic alteration produced by NAD is to increase the rate of acylation while not affecting deacylation. The presence of NAD appears to activate the attack of the active-site nucleophile on the carbonyl group of the substrate.

Effects of schedule information on the slowed fixed-ratio responding of schizophrenics

Instructions which provided schedule information were given to schizophrenics in an attempt to modify their slowed responding under a 40-response fixed-ratio (FR 40) schedule of penny reinforcements. Such information increased initial but not final rates of FR 40 responding.

Base-line muscle tensions and motoric responding of schizophrenics

Schizophrenics with high or low levels of frontalis muscle tensions while at rest (base-line) were instructed to respond (button-press) at different rates, allowed to respond at any rate they preferred, and reinforced for responding under different schedules of reinforcement. Information about response-reinforcement relationships was provided for each reinforcement schedule. High and low levels of base-line muscle tensions were associated with high and low rates of preferred and reinforced responding, respectively. Response rates also varied with different contingencies of reinforcement. Further, the data permit the following tentative conclusions: (a) under certain contingencies, responding may vary more with base-line muscle tensions than with the contingency of reinforcement, and (b) instructed rates of responding may not be correlated consistently with base-line muscle tensions.

Response rates and choices of schizophrenics under fixed-ratio contingencies of reinforcement

Schizophrenics (n = 12) were conditioned under different multiple fixed-ratio (mult FR FR) schedules of monetary reinforcement. The two FR components of these schedules differed in terms of ratio requirements (reinforcement frequency) or amounts of reinforcement per occurrence of reinforcement. Relatively low rates of responding were emitted by the schizophrenics under these schedules. Further, their response rates were positively correlated with the frequency and amount of FR reinforcement. In previous studies under comparable conditions, normal subjects tended to maximize reinforcement by responding at higher rates and to maintain these rates irrespective of the frequency or amount of FR reinforcement. When given the opportunity to select from among the two components of the mult FR FR schedules, the schizophrenics in the present study tended to respond like normal subjects in previous studies in that they chose to work predominantly under that FR component which provided the highest frequency or amount of reinforcement. It was concluded that schizophrenics resemble normals more and act more rationally in terms of maximizing reinforcement when reinforcement is less dependent upon rates of responding.

The effect of alcohol on dopamine metabolism in the caudate nucleus of an unanesthetized monkey

Previously it was shown that the acute administration of ethanol to the rat significantly alters the metabolism of the dopamine (DA) in liver but not in brain tissue. To extend this finding to the primate, two push-pull perfusion cannulae were implanted in the regions of the left and right caudate nucleus of a Macaca nemistrina. After 14C-DA was injected into the caudate, the site ws perfused with an artificial CSF and the perfusate analyzed for the major metalolites of DA. Ethanol was then administered in a dose of 6 g/kg by the nasopharyngeal route. The results show that very little alteration occurs in the metabolism of DA during or postethanol intoxication.

Retardation of ethanol absorption by food in the stomach

Ethanol diffusion from rat stomachs containing food particles was slower than from empty stomachs, and blood alcohol concentrations were lower in fed than in fasted rats given ethanol by gavage.

Increase in S-adenosyl-L-methionine decarboxylase activity during the transformation of chick embroy fibroblasts by Rous sarcoma virus

The increase in S-adenosyl-L-methionine decarboxylase activity in chick embryo fibroblasts after infection with Rous sarcoma virus has been studied. It has been shown that enzyme levels in transformed cells were two or three times higher than those of the non-infected controls. The activity of this enzyme was not elevated in chick embryo fibroblasts infected with a temperature sensitive mutant of Rous sarcoma virus (RSV-T5) at 42 degrees C, the non-permissive temperature. When the temperature of these infected cultures was shifted from 42 degrees C to 37 degrees C a two- or three-fold increase in decarboxlase activity was detected after 10 to 12 h. The half-live of S-adenosyl-L-methionine decarboxylase was practically identical in normal and RSV-transformed fibroblasts.

Vertical transmission of acquired ulcer susceptibility in the rat

Premature separation of rat pups from their dams greatly increases their susceptibility to restraint-induced gastric erosions. When prematurely separated female rats grow to adulthood and mate with stock males, their normally reared F 1 progeny also have increased susceptibility to restraint-induced erosions. Cross-fostering studies show that prenatal rather than postnatal factors transmit this susceptibility to the F 1 progeny.

Stability of ego defenses and endocrine responses in women prior to breast biopsy and ten years later

Thirty women with breast masses were evaluated psychologically and endocrinologically ten years ago while they were awaiting breast biopsy (3). Eight of these women proved to have benign fibrocystic disease and 22 had breast cancer. A significant (p < 0.05) positive correlation was found between extent of failure of psychological "defenses" and cortisol metabolite excretion rate in these 30 women. On follow-up, 12 women had died (11 with cancer and one who had had benign disease); 7 women were lost to follow-up. Of the remaining 11, one refused to participate, leaving 10 women for follow-up study (7 who had had mastectomy for breast cancer and 3 with benign breast lesions). They were reevaluated using the same assessment techniques as 10 years before. The psychological parameters and cortisol metabolite excretion rates did not show a significant change over the span of ten years. These data support the hypothesis that these psychological parameters and cortisol metabolite excretion rates reflect relatively abiding characteristics and are not as much affected by a "psychosocial threat" as previous research has suggested.

Mechanism of the magnesium ion activation of the catalytic activity of horse liver aldehyde dehydrogenase

The activity of the pI 5 isozyme of horse liver aldehyde dehydrogenase is markedly enhanced by some divalent metal ions (Ca, Mn, Mg), inhibited by others (Fe, Cu, Cd), totally inhibited by Hg, and not significantly affected by still others (Zn, Ni, Co). Steady-state kinetics show that with 0.5 mM Mg or Mn a 2-fold activation of the velocity measured at pH 7.5 occurs when propionaldehyde is the substrate. In the pre-steady state, the magnitude burst of NADH formulation is increased from 2 moles formed per mole of tetrameric enzyme to 4 moles formed in the presence of Mg. The stoichiometry of coenzyme (NADH, NAD, epsilon-NAD) binding is also increased from essentially 2 moles binding to 4 moles binding per mole enzyme in the presence of Mg. It appears that the enzyme exhibits half of the site reactivity in the absence of metal but has a full complement of catalytic sites in the presence.

A prospective classification of the respiratory manifestations of pollen sensitivity

Twenty pollen sensitive subjects were classified historically as Groups I-III based upon the elicitation of lower respiratory symptoms at (I) no time of the year, (II) only during the pollen season or (III) during and apart from the pollen season respectively. Neither antigen skin sensitivity nor antigen or mecholyl inhalational sensitivity was useful in delineating these three groups. However, pulmonary function tests during the season demonstrated changes in MMEFR and airflow at 25% vital capacity in Group II subjects, confirming our classifications.