SEARCH · PubMed Health

Results for “Hydroxybutyrates”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6Linked to original sources

PubMed1980

Variations of 3-hydroxybutyrate dehydrogenase activity in brain and liver mitochondria of the developing chick.

1. The 3-hydroxybutyrate dehydrogenase activity was estimated in the crude mitochondrial fraction isolated from the cerebral hemispheres, the optic lobes, the cerebellum and the liver of the chick between the 20th day of embryonic life and the 30th day of postnatal maturation. 2. The optimal conditions of liberation and of determination of 3-hydroxybutyrate dehydrogenase activity were studied in the mitochondrial fraction isolated from chick cerebral hemispheres and liver. 3. The subcellular distribution of the enzyme in the chick brain and liver is very different from that in the rat. 3-Hydroxybutyrate dehydrogenase is completely mitochondrial in the rat brain and liver whereas in the chick brain and liver, it is located in mitochondrial and microsomal fractions; moreover, a third component can even be found in the soluble fraction of chick liver. 4. The 3-hydroxybutyrate dehydrogenase activity reaches the same value in the three areas of 20-day-old chick embryo brain. Between this stage and the 4th day after hatching, it increases to reach the same peak in the three areas. This peak however, appears at different stages according to the considered brain area. At 30 days after hatching, the enzyme activity is higher in the cerebellum than in the cerebral hemispheres and optic lobes. 5. The activity of hepatic 3-hydroxybutyrate dehydrogenase is 10 to 20 times lower than in the brain. It does not significantly change between 1 day before and 4 days after hatching and increases 2-fold between 4 and 30 days after hatching. 6. The variations of 3-hydroxybutyrate dehydrogenase activity in chick brain indicate correlations of this enzyme activity with development, particularly related to the nutritional state of the chicks. The fairly important differences in the activity of 3-hydroxybutyrate dehydrogenase in the liver of the chick and the rat enable us to come to a better understanding of the regulation of the concentration of the different ketone bodies in the blood of the chick and the rat. Moreover, the presence of the microsomal component of 3-hydroxybutyrate dehydrogenase in chick brain probably originates in the low concentration of acetoacetate in chick blood.

Animals↗

PubMed1973

The regulation of poly-beta-hydroxybutyrate metabolism in Azotobacter beijerinckii.

1. The enzymes beta-ketothiolase, acetoacetyl-CoA reductase, acetoacetate-succinate CoA-transferase (;thiophorase') and d(-)-3-hydroxybutyrate dehydrogenase have been partially purified from crude extracts of glucose-grown nitrogen-fixing batch cultures of Azotobacter beijerinckii. The condensation of acetyl-CoA to acetoacetyl-CoA catalysed by beta-ketothiolase is inhibited by CoASH, and the reverse reaction is inhibited by acetoacetyl-CoA. Acetoacetyl-CoA reductase has K(m) for acetoacetyl-CoA of 1.8mum and is inhibited by acetoacetyl-CoA above 10mum. The enzyme utilizes either NADH or NADPH as electron donor. The second enzyme of poly-beta-hydroxybutyrate degradation, d(-)-3-hydroxybutyrate dehydrogenase, is NAD(+)-specific and is inhibited by NADH, pyruvate and alpha-oxoglutarate. CoA transferase is inhibited by acetoacetate, the product of hydroxybutyrate oxidation. In continuous cultures poly-beta-hydroxybutyrate biosynthesis ceased on relaxation of oxygen-limitation and the rates in situ of oxygen consumption and carbon dioxide evolution of such cultures increased without a concomitant increase in glucose uptake. 2. On the basis of these and other findings a cyclic mechanism for the biosynthesis and degradation of poly-beta-hydroxybutyrate is proposed, together with a regulatory scheme suggesting that poly-beta-hydroxybutyrate metabolism is controlled by the redox state of the cell and the availability of CoASH, pyruvate and alpha-oxoglutarate. beta-Ketothiolase plays a key role in the regulatory process. Similarities to the pathways of poly-beta-hydroxybutyrate biosynthesis and degradation in Hydrogenomonas are discussed.

Acetoacetates↗

PubMed1995

The mechanism of action of hepatic sympathetic nerves on ketone-body output from perfused rat liver. The effect of the interaction of noradrenaline with ATP on the release of beta-hydroxybutyrate.

The regulatory mechanism of ketone-body output by the hepatic sympathetic nerves was studied in rat liver perfused in situ. Enrichment of the perfusion medium with 1 mM octanoate increased the basal ketone-body output from the liver up to 1.5 mumol.min-1.g liver-1. Under these conditions, electrical stimulation of the hepatic nerves (20 V, 20 Hz, 2 ms) decreased the output of both acetoacetate and beta-hydroxybutyrate, and was accompanied by an accumulation of beta-hydroxybutyrate in the liver. The effects of nerve stimulation were inhibited by the alpha 1-antagonist bunazosin (10 microM). However, noradrenaline, a typical sympathetic neurotransmitter, at a concentration of 1 microM decreased the output of acetoacetate but did not affect beta-hydroxybutyrate output. Prostaglandin F2 alpha at a concentration of 10 microM produced an effect similar to treatment with noradrenaline, without a decrease in beta-hydroxybutyrate output. ATP at 50 microM, however, decreased the output of both acetoacetate and beta-hydroxybutyrate and increased the tissue concentration of beta-hydroxybutyrate, mimicking the effect of nerve stimulation. Moreover, in the presence of 0.2 microM ATP, a concentration that produced neither metabolic nor hemodynamic changes, noradrenaline (1 microM) was shown to decrease the beta-hydroxybutyrate output. These results indicate the possible involvement of ATP in the action of hepatic sympathetic nerves on beta-hydroxybutyrate output from the liver, presumably through its interaction with noradrenaline.

3-Hydroxybutyric Acid↗

PubMed1992

Quantitative histochemical changes in enzymes involved in energy metabolism in the rat brain during postnatal development. II. Glucose-6-phosphate dehydrogenase and beta-hydroxybutyrate dehydrogenase.

The postnatal maturation of glucose-6-phosphate and beta-hydroxybutyrate dehydrogenase activity was assessed by histochemistry in rats at eight postnatal stages, P0, P5, P10, P14, P17, P21, P35 and the adult stage. Enzyme activities were revealed on cryostat brain sections with nitroblue tetrazolium. Both enzyme activities were low and homogeneous at birth, and increased to reach a peak in all areas studied, at P17 for beta-hydroxybutyrate dehydrogenase and at P21 for glucose-6-phosphate dehydrogenase. Then, glucose-6-phosphate dehydrogenase activity decreased regularly by 20-49% from P21 to adult stage, except in cerebellar white matter where activity did not change after P21. beta-hydroxybutyrate dehydrogenase activity decreased regularly from P17 to adult stage in globus pallidus, hippocampus, thalamus, brainstem, genu of corpus callosum and cerebellar white matter. It sensorimotor cortex, medial geniculate body, caudate nucleus, hypothalamus and inferior colliculus, beta-hydroxybutyrate dehydrogenase activity stayed stable between P17 and P35 and decreased thereafter to adult levels. Finally, in parietal, auditory and cerebellar cortices, beta-hydroxybutyrate dehydrogenase activity either stayed stable or slightly increased after P17. The present study shows that there is a quite good correlation between postnatal changes in cerebral glucose-6-phosphate and beta-hydroxybutyrate dehydrogenase activities and the importance of pentose phosphate pathway and ketone body utilization in the developing brain. Our results also reflect the regional heterogeneity of beta-hydroxybutyrate utilization in the adult rat brain, translating into a remaining high activity of beta-hydroxybutyrate dehydrogenase in cerebral cortex.

Aging↗

PubMed1977

Influence of acetate on the metabolism of beta-hydroxybutyrate in the perfused hind-quarter of the rat.

The effect of acetate, at concentrations normally found during ethanol combustion in intact animals and man in vivo, on the uptake and oxidation of beta-hydroxybutyrate by the perfused rat hind-quarter was studied. The addition of acetate did not significantly affect the total uptake of beta-hydroxybutyrate, but caused a 40% decrease in the oxidation of beta-hydroxybutyrate to CO2. The oxidation of 14C-beta-hydroxybutyrate to 14CO2 accounted for about 10% of the total oxygen consumption by the perfused muscle in the absence of acetate. In the presence of acetate this figure was reduced to about 5%. The addition of beta-hydroxybutyrate did not significantly affect the metabolic fate of 14C-acetate. It is concluded that acetate is preferred as oxidative substrate to beta-hydroxybutyrate. The inhibited oxidation of beta-hydroxybutyrate by acetate did not affect the concentration ratio between beta-hydroxybutyrate and acetoacetate in the medium at the end of the perfusion, indicating that the ability of the muscle tissue to restore an increased redoxlevel, "exported" from the liver during ethanol combustion to extrahepatic tissues, was not impaired by acetate.

Acetates↗

PubMed2000

The ketogenic diet: seizure control correlates better with serum beta-hydroxybutyrate than with urine ketones.

The objective of this study was to determine the relationship between beta-hydroxybutyrate levels and seizure control in children on the ketogenic diet. Seventy-four children on the ketogenic diet presenting for routine follow-up visits had blood levels of beta-hydroxybutyrate correlated with their seizure control. Forty-two children admitted for initiation of the ketogenic diet had urine ketones measured by dipstick and correlated with simultaneous blood levels of beta-hydroxybutyrate. Blood beta-hydroxybutyrate levels statistically correlated with seizure control (P = .003). Children with blood beta-hydroxybutyrate levels greater than 4 mmol/L were significantly more likely to have a decrease in seizure frequency than those with levels less than 4 mmol/L. Urine ketones of 4+ (160 mmol/L) were found on dipstick when blood beta-hydroxybutyrate levels exceeded 2 mmol/L. Seizure control correlates with blood beta-hydroxybutyrate levels and is more likely when blood beta-hydroxybutyrate levels are greater than 4 mmo/L. The traditional measurement of urine ketones by dipsticks in children on the ketogenic diet provides a less than optimal assessment of the degree of blood ketosis. Three to four plus (80-160 mmol/L) urine ketones are necessary, but not necessarily sufficient, to achieve optimal seizure control in children on the ketogenic diet. At present, however, urine ketones are the only readily available inexpensive approach to ketone assessment.

3-Hydroxybutyric Acid↗

PubMed1995

Gamma-hydroxybutyrate promotes oscillatory activity of rat and cat thalamocortical neurons by a tonic GABAB, receptor-mediated hyperpolarization.

The actions of gamma-hydroxybutyrate, a drug known to lead to an increase in nocturnal slow wave sleep and induce epileptic states following systemic application, on the membrane properties of thalamocortical neurons from brain slices of the rat and cat dorsal lateral geniculate nucleus were studied using sharp electrode intracellular recordings. Gamma-hydroxybutyrate applied by addition to the perfusion medium led to a concentration-dependent and reversible hyperpolarization of the membrane potential accompanied by a decrease in apparent input resistance (0.1 mM: 2.3 +/- 0.3 mV, 9.5 +/- 1.0%; 10 mM: 11.3 +/- 1.3 mV, 37.5 +/- 10.8%, respectively). In six of seven neurons the iontophoretic or bath (0.1-0.2 mM) application of low concentrations of gamma-hydroxybutyrate led to a hyperpolarization accompanied by the appearance of low-frequency (< 4 Hz) membrane potential oscillations crowned by bursts of action potentials, when the membrane potential of these neurons was initially set depolarized to the range where ongoing oscillatory activity occurred. The gamma-hydroxybutyrate-elicited hyperpolarization was reversibly antagonized by the co-application of the GABAB receptor antagonist CGP 35348 (0.4-1 mM), but was not affected by the putative gamma-hydroxybutyrate receptor antagonist NCS 382 (0.1-5 mM) or tetrodotoxin (1 microM), suggesting that gamma-hydroxybutyrate tonically activates postsynaptic GABAB receptors. The gamma-hydroxybutyrate-induced promotion of oscillatory activity and action potential burst firing of thalamocortical neurons may be one mechanism by which gamma-hydroxybutyrate leads to an increase in the deep stages of sleep and the generation of electroencephalogram and behavioural patterns typical of absence epilepsy.

Action Potentials↗

PubMed2004

Effects of sustained gamma-hydroxybutyrate treatments on spontaneous and evoked firing activity of locus coeruleus norepinephrine neurons.

BACKGROUND: Gamma-hydroxybutyrate is currently used to promote nighttime sleep in the treatment of narcolepsy; however, it is also a drug of abuse ("Liquid Ecstasy") associated with a withdrawal syndrome with anxiety features. Of interest, the activity of locus coeruleus neurons is a reflective index of these above mentioned behavioral states. METHODS: Using in vivo extracellular unitary recordings, sustained administration of gamma-hydroxybutyrate (40 mg/kg/day via minipump implanted subcutaneously) on the spontaneous and sensory-evoked burst firing of locus coeruleus norepinephrine neurons was assessed in rats. RESULTS: A 2-day and 10-day gamma-hydroxybutyrate administration decreased the spontaneous firing activity of locus coeruleus neurons by 52% and 54%, respectively, when compared with controls. A similar degree of attenuation on evoked burst firing of norepinephrine neurons also occurred in these rats (2-day gamma-hydroxybutyrate: 47% and 10-day gamma-hydroxybutyrate: 58%), when compared with controls. In contrast, rats treated with gamma-hydroxybutyrate for 10 days followed by removal of the minipump for 36 hours resulted in a 33% augmentation in spontaneous locus coeruleus activity as compared with controls. Furthermore, a robust 79% increase in burst firing in response to paw-pinch was exhibited in theses rats. CONCLUSIONS: Chronic gamma-hydroxybutyrate treatment inhibits the spontaneous and sensory-evoked burst firing of locus coeruleus norepinephrine neurons, whereas these indices are enhanced during drug withdrawal. The alteration in norepinephrine activity during chronic gamma-hydroxybutyrate administration may contribute to the ability of this agent to induce sleep and regulate narcoleptic episodes. Enhanced norepinephrine activity during withdrawal may be related to symptoms of anxiety on rapid termination of this drug in abusers.

Anesthetics, Intravenous↗

PubMed2006

Gamma-hydroxybutyric acid affects the acquisition and reinstatement of cocaine-induced conditioned place preference in mice.

Cocaine addicts very often use different combinations of cocaine and other drugs of abuse such as gamma-hydroxybutyric acid. The objective of the present work was to evaluate the impact of gamma-hydroxybutyric acid administration on the rewarding actions of cocaine, using the conditioned place preference procedure. Cocaine-induced conditioned place preference (50 mg/kg) was studied after pairing this drug with different gamma-hydroxybutyric acid doses (6.25, 12.5, 25, 50 and 100 mg/kg) during either the acquisition or the expression phase of the procedure. After conditioned place preference had been established, and the preference was extinguished, a reinstatement was induced by a dose of cocaine half of that used to produce conditioning, or by gamma-hydroxybutyric acid alone or by both drugs together. The doses of 12.5 and 100 mg/kg of gamma-hydroxybutyric acid blocked the acquisition of cocaine-induced conditioned place preference, and no dose affected the expression of this conditioning. Reinstatement was abolished only with the dose of 25 mg/kg gamma-hydroxybutyric acid, which did not reinstate the preference by itself. This is the first study evaluating the effects of gamma-hydroxybutyric acid on the rewarding properties of cocaine using the conditioned place preference procedure. The principal conclusion of the study is that gamma-hydroxybutyric acid does not enhance the rewarding effect of cocaine, and within a narrow margin of effective doses, blocks the acquisition and reinstatement of cocaine-induced preference.

Anesthetics, Intravenous↗

PubMed1971

Poly-beta-hydroxybutyrate Utilization by Soybean (Glycine max Merr.) Nodules and Assessment of Its Role in Maintenance of Nitrogenase Activity.

Soybean (Glycine max) nodule bacteroids contain high concentrations of poly-beta-hydroxybutyrate and possess a depolymerase system that catalyzes the hydrolysis of the polymer. Changes in poly-beta-hydroxybutyrate content and in activities of nitrogenase, beta-hydroxybutyrate dehydrogenase, and isocitrate lyase in nodule bacteroids were investigated under conditions in which the supply of carbohydrate from the soybean plants was interrupted. The poly-beta-hydroxybutyrate content of bacteroids did not decrease appreciably until the carbohydrate supply from the host plants was limited by incubation of excised nodules, incubation of plants in the dark, or by senescence of the host plant. Isocitrate lyase activity in bacteroids was not detected until poly-beta-hydroxybutyrate utilization appeared to begin. The presence of a supply of poly-beta-hydroxybutyrate in nodule bacteroids was not sufficient for maintenance of high nitrogenase activity under conditions of limited carbohydrate supply from the host plant. An unusually high activity of beta-hydroxybutyrate dehydrogenase was observed in bacteroid extracts but no significant change in the activity of this enzyme was observed as a result of apparent utilization of poly-beta-hydroxybutyrate by nodule bacteroids.

Journal Article↗

PubMed1987

Metabolism of S-3-hydroxybutyrate in the perfused rat liver.

The metabolism of millimolar concentrations of S-3-hydroxybutyrate (the unnatural enantiomer) has been studied in perfused livers from fed and starved rats. Protocols were designed to test whether S-3-hydroxybutyrate is metabolized in the cytosol or in the mitochondria via a racemase, a dehydrogenase, or a ligase. Our data show that only a minor fraction of S-3-hydroxybutyrate metabolism could occur via L-3-hydroxyacid dehydrogenase. Most of the metabolism of S-3-hydroxybutyrate proceeds via mitochondrial activation. In rat liver, S-3-hydroxybutyrate is converted to physiological ketone bodies (i.e., R-3-hydroxybutyrate, acetoacetate, acetone), lipids, and CO2. Carbons from S-3-hydroxybutyrate are transferred from the mitochondria to the cytosol mostly via citrate and the citrate cleavage pathway.

3-Hydroxyacyl CoA Dehydrogenases↗

PubMed2007

The bacterial storage compound poly-beta-hydroxybutyrate protects Artemia franciscana from pathogenic Vibrio campbellii.

Infections caused by antibiotic-resistant luminescent Vibrios can cause dramatic losses in aquaculture. In this study, the short-chain fatty acid beta-hydroxybutyrate and its polymer poly-beta-hydroxybutyrate were investigated as possible new biocontrol agents. beta-Hydroxybutyrate was shown to completely inhibit the growth of pathogenic Vibrio campbelli at 100 mM. Moreover, the addition of 100 mM of this fatty acid to the culture water of Artemia nauplii infected with the V. campbelli strain significantly increased the survival of the nauplii. As Artemia is a non-selective and particle filter feeder, we also investigated whether poly-beta-hydroxybutyrate particles could be used to protect Artemia from the pathogenic V. campbellii. The addition of 100 mg l(-1) poly-beta-hydroxybutyrate or more to the Artemia culture water offered a preventive and curative protection from the pathogen as a significantly enhanced survival was noticed. If added as a preventive treatment, a complete protection of infected nauplii (no significant mortality compared with uninfected nauplii) was observed at 1000 mg l(-1) poly-beta-hydroxybutyrate. Our data indicate that the use of poly-beta-hydroxybutyrate might constitute an ecologically and economically sustainable alternative strategy to fight infections in aquaculture.

3-Hydroxybutyric Acid↗

PubMedDate not supplied

[Effect of experimental myocardial infarct on the rate of NADH and 3-hydroxybutyrate oxidation in heart mitochondria].

The rate of oxidation of NADH and 3-hydroxybutyrate was studied in heart mitochondria after short-term (60 min) occlusion of coronary artery and the subsequent reperfusion. Addition of NAD increased the rate of 3-hydroxybutyrate oxidation, lowered in mitochondria of impaired tissue, but no complete restoration occurred. Th 3-hydroxybutyrate dehydrogenase activity was decreased by 25%. The rate of NADH oxidation in ultrasonicated mitochondria from the infarction zone exceeded 2-fold the rate of 3-hydroxybutyrate oxidation. These data suggest that deficiency of NAD limited primarily the rate of 3-hydroxybutyrate oxidation in heart mitochondria under conditions of experimental myocardial infarction. The level of 3-hydroxybutyrate dehydrogenase activity appears to restrict the rate of 3-hydroxybutyrate oxidation after addition of NAD.

Adenosine Diphosphate↗

PubMed1978

Characterization of beta-hydroxybutyrate transport in rat erythrocytes and thymocytes.

A method was developed for study of beta-hydroxybutyrate transport in erythrocytes and thymocytes. Critical to the method was a centrifugal separation of cells from medium which took advantage of beta-hydroxybutyrate transport's temperature dependence and inhibition by phloretin and methylisobutylxanthine, all of which are demonstrated in this work. These properies suggested mediated transport, as did saturation kinetics and inhibition by several agents including pyruvate and alpha-cyanocinnamate. Most conclusive in this regard was a 2-fold preference for D- over L-beta-hydroxybutyrate. Entry was not Na+ dependent. It was stimulated by substitution of SO2-4 for most of the Cl-. The equilibrium beta-hydroxybutyrate space was much higher than the Cl- space of thymocytes, suggesting that beta-hydroxybutyrate entry is not associated with net inward negative current and is not coupled to outward Cl- or inward K+ movement (assuming that K+ is at elecrochemical equilibrium). Coupling to H+ entry or OH- exit is compatible with the result. These findings are consistent with beta-hydroxybutyrate entry by the carboxylate transport site which has been studied extensively with pyruvate and lactate as permeants. The Cl-/HCO-3 exchange carrier did not appear to contribute significantly to beta-hydroxybutyrate transport.

Animals↗

PubMed2002

Determination of poly-beta-hydroxybutyric acid in Bacillus thuringiensis by capillary zone electrophoresis with indirect ultraviolet absorbance detection.

A new capillary electrophoresis method for determining poly-beta-hydroxybutyric acid (PHB) in Bacillus thuringiensis was established. Poly-beta-hydroxybutyric acid in samples was hydrolyzed by sulphuric acid and neutralized by Ba(OH)2. The content of produced beta-hydroxybutyrate was then determined by capillary zone electrophoresis (CZE) with indirect UV detection at 254 nm. With 5 mM p-hydroxybenzoate and 0.5 mM tetradecyltrimethylammonium bromide (TTAB) at pH 8.0 as carrier electrolyte, beta-hydroxybutyrate can be determined within 6 min. Standard regression equation was made by beta-hydroxybutyrate, and the linear range was 2-1000 microg/ml. The relative standard deviations (RSDs) for migration time and peak area are both less than 1.0%. The detection limit for beta-hydroxybutyrate was 0.2 microg/ml, which is two to three orders of magnitude lower than that of the gas chromatography (GC) method. The capillary electrophoresis method was successfully applied to determine poly-beta-hydroxybutyric acid in fermentation broth and single colony. The added standard recovery was 96%.

Bacillus thuringiensis↗

PubMed2000

Design and structure-activity relationship analysis of ligands of gamma-hydroxybutyric acid receptors.

With the use of [3H]gamma-hydroxybutyric acid, binding experiments allowed the screening of new compounds as ligands of gamma-hydroxybutyric acid receptors. Starting from the acid-alcohol gamma-hydroxybutyric acid structure, structure-activity relation analysis and lead optimization highlighted gamma-hydroxybutyric acid derivatives with significantly increased affinities, when compared with the affinity of gamma-hydroxybutyric acid. Further pharmacological studies with the use of gamma-hydroxybutyric acid derivatives allowed the characterization of the first competitive antagonist acting at gamma-hydroxybutyric acid receptors (NCS 382).

Benzocycloheptenes↗

PubMed2002

Rapid and sensitive detection of urinary 4-hydroxybutyric acid and its related compounds by gas chromatography-mass spectrometry in a patient with succinic semialdehyde dehydrogenase deficiency.

We describe the rapid and sensitive detection of 4-hydroxybutyric acid, which is a marker compound for succinic semialdehyde dehydrogenase (SSADH) deficiency. Urinary 4-hydroxybutyric acid and 3,4-dihydroxybutyric acid were targeted, quantified by gas chromatography-mass spectrometry after simplified urease digestion in which lactone formation from gamma-hydroxy acids is minimized. The recovery of 4-hydroxybutyric acid using this method was over 93%. 2,2-Dimethylsuccinic acid was used as an internal standard. The detection limit of this method was 1 nmol ml(-1) for both 4-hydroxybutyric acid and 3,4-dihydroxybutyric acid. The urinary concentrations of 4-hydroxybutyric acid and of 3,4-dihydroxybutyric acid from the patient with an SSADH deficiency were 880-3628 mmol mol(-1) creatinine (control; 3.3+/-3.3 mmol mol(-1) creatinine) and 810-1366 mmol mol(-1) creatinine (control; 67.4+/-56.2 mmol mol(-1) creatinine), respectively. The simplified urease digestion of urine is very useful for quantifying 4-hydroxybutyric acid and its related compounds in patients with 4-hydroxybutyric aciduria.

Aldehyde Oxidoreductases↗

PubMed1972

3-hydroxybutyrate dehydrogenase in tissues from normal and ketonaemic sheep.

1. In liver, rumen epithelium and kidney cortex of the sheep, a dehydrogenase active against dl-3-hydroxybutyrate occurred in both the cytosol and particulate fractions of the tissues. In brain, heart, skeletal and smooth muscles, the enzyme occurred only in the particulate fraction. 2. Enzyme activity in the cytoplasmic fraction of liver and rumen epithelium was similar with either d(-)-3-hydroxybutyrate or dl-3-hydroxbutyrate, but was less with acetoacetate as the substrate. The cytosol fraction of kidney cortex showed very little activity with d(-)-3-hydroxybutyrate, confirming that most of the activity with dl-3-hydroxybutyrate was with the l(+) isomer in this tissue. 3. 3-Hydroxybutyrate dehydrogenase activities in the cytosol and particulate fractions of liver, rumen epithelium and kidney cortex and in the particulate fraction of brain tissue were not stimulated by phosphatidylcholine, unlike the enzyme in sheep muscle and in tissues of other species. 4. The activity of 3-hydroxybutyrate dehydrogenase was not increased significantly in any of the tissues of ketonaemic sheep. 5. Comparison of rates of 3-hydroxybutyrate production in vivo with the enzyme activity in ketogenic tissue suggested that in sheep the maximum rate of production might be limited by this activity.

Animals↗