Ischemic heart disease: metabolic approaches to management

The number of patients with coronary artery disease and its risk factors is increasing in Western nations. New treatments for these patients may soon include a class of agents known as the metabolic modulators. This group of agents consists of the partial fatty acid oxidation inhibitors trimetazidine and ranolazine, as well as dichloroacetate, which promotes carbohydrate utilization. Metabolic modulators also include the nutriceuticals L-carnitine and D-ribose. The available evidence regarding the benefits of each of these five agents is reviewed.

Dichloroacetate prevents and reverses pulmonary hypertension by inducing pulmonary artery smooth muscle cell apoptosis

The pulmonary arteries (PA) in pulmonary arterial hypertension (PAH) are constricted and remodeled;. They have suppressed apoptosis, partly attributable to suppression of the bone morphogenetic protein axis and selective downregulation of PA smooth muscle cell (PASMC) voltage-gated K+ channels, including Kv1.5. The Kv downregulation-induced increase in [K+]i, tonically inhibits caspases, further suppressing apoptosis. Mitochondria control apoptosis and produce activated oxygen species like H2O2, which regulate vascular tone by activating K+ channels, but their role in PAH is unknown. We show that dichloroacetate (DCA), a metabolic modulator that increases mitochondrial oxidative phosphorylation, prevents and reverses established monocrotaline-induced PAH (MCT-PAH), significantly improving mortality. Compared with MCT-PAH, DCA-treated rats (80 mg/kg per day in drinking water on day 14 after MCT, studied on day 21) have decreased pulmonary, but not systemic, vascular resistance (63% decrease, P<0.002), PA medial thickness (28% decrease, P<0.0001), and right ventricular hypertrophy (34% decrease, P<0.001). DCA is similarly effective when given at day 1 or day 21 after MCT (studied day 28) but has no effect on normal rats. DCA depolarizes MCT-PAH PASMC mitochondria and causes release of H2O2 and cytochrome c, inducing a 10-fold increase in apoptosis within the PA media (TUNEL and caspase 3 activity) and decreasing proliferation (proliferating-cell nuclear antigen and BrdU assays). Immunoblots, immunohistochemistry, laser-captured microdissection-quantitative reverse-transcription polymerase chain reaction and patch-clamping show that DCA reverses the Kv1.5 downregulation in resistance PAs. In summary, DCA reverses PA remodeling by increasing the mitochondria-dependent apoptosis/proliferation ratio and upregulating Kv1.5 in the media. We identify mitochondria-dependent apoptosis as a potential target for therapy and DCA as an effective and selective treatment for PAH.

Chronic treatment of mitochondrial disease patients with dichloroacetate

Clinical features are reported for 37 patients with various mitochondrial disorders, treated with sodium dichloroacetate (DCA) for 3 weeks to 7 years (mean 3.25 years) at 11-50 mg/kg/day (34.6+/-13.1) in an open-label format. DCA pharmacokinetics showed half-times approximately 86 min for the first intravenous dose of 50 mg/kg, 3.2 h for a subsequent intravenous dose 4-6 h later, and 11 h after continued oral dosing of 12.5-25 mg/kg twice daily. Basal blood and CSF lactate (mean values at entry 29.6 and 46.8 mg/dL, respectively) decreased at 3 months (to 18.1 and 34.2, respectively) and 12 months (to 17.7 and 33.1, respectively). There was some attenuation of the blood lactate response to oral fructose but not glucose, although the baseline lactate was lower with DCA. A standardized neurologic inventory showed stabilization or improvement over one year. The subjective impression of overall disease course was worsening in 21.6%, improvement in 48.6%, and no discernable effect in 29.7%. Among 8 patients who had 17 stroke-like events in 0.25-5 years prior to study entry, there were a total of 2 events over 3-6 years of treatment. In two cases institution of DCA resulted in dramatic relief of severe headaches which had been refractory to narcotics. Given variability of symptoms and limited understanding of natural history of mitochondrial disease, it is difficult to determine the efficacy of DCA in this open-label study, but there did appear to be some cases in which there were at least temporary benefits.

Bench-to-bedside review: treating acid-base abnormalities in the intensive care unit - the role of buffers

The recognition and management of acid-base disorders is a commonplace activity for intensivists. Despite the frequency with which non-bicarbonate-losing forms of metabolic acidosis such as lactic acidosis occurs in critically ill patients, treatment is controversial. This article describes the properties of several buffering agents and reviews the evidence for their clinical efficacy. The evidence supporting and refuting attempts to correct arterial pH through the administration of currently available buffers is presented.

Dichloroacetate therapy attenuates the blood lactate response to submaximal exercise in patients with defects in mitochondrial energy metabolism

We determined acute and chronic effects of dichloroacetate (DCA) on maximal (MAX) and submaximal (SUB) exercise responses in patients with abnormal mitochondrial energetics. Subjects (n = 9) completed a MAX treadmill bout 1 h after ingesting 25 mg/kg DCA or placebo (PL). A 15-min SUB bout was completed the next day while receiving the same treatment. After a 1-d washout, MAX and SUB were repeated while receiving the alternate treatment (acute). Gas exchange and heart rate were measured throughout all tests. Blood lactate (Bla) was measured 0, 3, and 10 min after MAX, and 5, 10, and 15 min during SUB. MAX and SUB were repeated after 3 months of daily DCA or PL. After a 2-wk washout, a final MAX and SUB were completed after 3 months of alternate treatment (chronic). Average Bla during SUB was lower (P < 0.05) during both acute (1.99 +/- 1.10 vs. 2.49 +/- 1.52 mmol/liter) and chronic (1.71 +/- 1.37 vs. 2.39 +/- 1.32 mmol/liter) DCA vs. PL despite similar exercise intensities between conditions ( approximately 75 and 70% maximal exercise capacity during acute and chronic treatment). Thus, although DCA does not alter MAX responses, acute and chronic DCA attenuate the Bla response to moderate exercise in patients with abnormal mitochondrial energetics.

The effects of dichloroacetate in a rabbit model of acute hind-limb ischemia and reperfusion

BACKGROUND

Dichloroacetate (DCA) is a drug that allows pyruvate dehydrogenase to remain active under anaerobic conditions by inhibiting the inactivating enzyme, pyruvate dehydrogenase kinase. We hypothesize that the administration of DCA during acute limb ischemia may have a beneficial effect by reducing the severity of anaerobic metabolism and lessening the irreversible injury.

STUDY DESIGN

We studied a rabbit model using unilateral ligation of the iliac artery or femoral artery to evaluate two degrees of ischemia. After 2 hours of hind-limb ischemia, the animals were administered IV DCA (15 mg/kg) or an equivalent volume of saline.

RESULTS

Higher serum lactate levels were seen after high compared to low ligation in control animals consistent with more severe ischemia. DCA treatment significantly reduced serum lactate levels after both high and low ligation. Similarly, the rise in percentage end-tidal CO(2) after reperfusion was less after DCA. All animals regained hind-limb function after the procedure, but ischemia or reperfusion resulted in appreciable muscle necrosis (> 10% area) in 50% of high- and 22% of low-ligation control animals. DCA treatment eliminated significant muscle necrosis in 100% of high-ligation animals. Muscle histology was similar in control and DCA-treated low-ligation animals.

CONCLUSIONS

Treatment with DCA during acute arterial occlusion did significantly lower markers of anaerobic metabolism and reduced muscle necrosis in a rabbit model of acute hind-limb ischemia. DCA delivery through collateral blood flow may prolong the ischemia time interval before the onset of irreversible muscle injury and potential limb loss.

Efficacy of dichloroacetate as a lactate-lowering drug

Dichloroacetate (DCA) decreases blood, cerebral spinal fluid, and intracellular lactate concentrations by activating the mitochondrial pyruvate dehydrogenase enzyme complex. The authors reviewed the efficacy of this investigational drug in the treatment of acquired or congenital forms of lactic acidosis from data in 40 English-language publications. The hypolactatemic effect of DCA occurs over a broad range of pretreatment lactate concentrations and is directly related to the baseline lactate level. The maximum lactate-lowering effect of the drug is dependent on its dose but independent of time following its administration. Recent clinical studies of acquired lactic acidosis suggest that DCA could be rapidly effective in reducing this risk factor of mortality in patients with mild hyperlactatemeia.

Population kinetics, efficacy, and safety of dichloroacetate for lactic acidosis due to severe malaria in children

The authors conducted a randomized, double-blind, placebo-controlled trial of intravenous dichloroacetate (DCA) for the purpose of treating lactic acidosis in 124 West African children with severe Plasmodium falciparum malaria. Lactic acidosis independently predicts mortality in severe malaria, and DCA stimulates the oxidative removal of lactate in vivo. A single infusion of 50 mg/kg DCA was well tolerated. When administered at the same time as a dose of intravenous quinine, DCA significantly increased the initial rate and magnitude of fall in blood lactate levels and did not interfere with the plasma kinetics of quinine. The authors developed a novel population pharmacokinetic-pharmacodynamic indirect-response model for DCA that incorporated characteristics associated with disease reversal. The model describes the complex relationships among antimalarial treatment procedures, plasma DCA concentrations, and the drug's lactate-lowering effect. DCA significantly reduces the concentration of blood lactate, an independent predictor of mortality in malaria. Its prospective evaluation in affecting mortality in this disorder appears warranted.

Dichloroacetate therapy in Leigh syndrome with a mitochondrial T8993C mutation

A 6-year-old female with Leigh syndrome associated with a T-to-C mutation at nucleotide 8993 of mitochondrial deoxyribonucleic acid (T8993C) was treated with dichloroacetate, once during the first acute deterioration after a febrile illness and another time when she demonstrated subacute regression without precipitating events. Dichloroacetate reversed the clinical course on both occasions, and diffuse lesions in the midbrain revealed on magnetic resonance imaging during the second episode disappeared completely. However, dichloroacetate could not prevent the second acute deterioration associated with a febrile illness that occurred during the second treatment. Thus dichloroacetate treatment, although limited, was effective for T8993C-associated Leigh syndrome.

Renal manifestations of congenital lactic acidosis

Congenital lactic acidoses (CLAs) constitute a group of rare inborn errors of mitochondrial metabolism in which cellular energy failure is the defining biochemical abnormality. We report the principal manifestations of renal dysfunction in 35 children with CLA caused by defects in either the pyruvate dehydrogenase multienzyme complex or one or more components of the respiratory chain. The most prominent renal abnormalities included bicarbonaturia, phosphaturia, hypercalciuria, complete Fanconi's syndrome, proteinuria, and decreased glomerular filtration rate. These data were compared with those from 79 previously published cases. Clinical manifestations of renal dysfunction in CLA are common and may be the first presenting sign of the disease. The glomerulus and proximal renal tubule appear to be the anatomic sites most vulnerable to abnormal mitochondrial energy transduction. We propose that the primary defect in mitochondrial energy metabolism, together with the consequent intracellular accumulation of lactate and hydrogen ions, precipitates a state of tissue injury that, unless interrupted, becomes self-perpetuating and ultimately leads to renal cell death.

Mouse models of Huntington's disease

Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder. In 1993 the mutation that causes HD was identified as an unstable expansion of CAG repeats in the IT15 gene. Since then one of the most important advances in HD research has been the generation of various mouse models that enable the exploration of early pathological, molecular and cellular abnormalities produced by the mutation. In addition, these models have made it possible to test different pharmacological approaches to delay the onset or slow the progression of HD. In this article, insights gained from mouse models towards the understanding of HD and the design of new therapeutic strategies are discussed.

Dichloroacetate exerts therapeutic effects in transgenic mouse models of Huntington's disease

Dichloroacetate (DCA) stimulates pyruvate dehydrogenase complex (PDHC) activity and lowers cerebral lactate concentrations. In the R6/2 and N171-82Q transgenic mouse models of Huntington's disease (HD), DCA significantly increased survival, improved motor function, delayed loss of body weight, attenuated the development of striatal neuron atrophy, and prevented diabetes. The percentage of PDHC in the active form was significantly reduced in R6/2 mice at 12 weeks of age, and DCA ameliorated the deficit. These results provide further evidence for a role of energy dysfunction in HD pathogenesis and suggest that DCA may exert therapeutic benefits in HD.

Dichloroacetate treatment for severe refractory metabolic acidosis during neonatal sepsis

We describe a preterm neonate with documented group B Streptococcus sepsis and associated metabolic acidosis whose lactic acidemia was refractory to conventional sodium bicarbonate therapy but responded well to dichloroacetate treatment.

Role of metabolically active drugs in the management of ischemic heart disease

This article reviews the fundamentals of myocardial energy metabolism and selectively outlines the use of several metabolically active drug therapies in the treatment of ischemic heart disease. These drugs - ranolazine, trimetazidine, dichloroacetate (DCA), glucose-insulin-potassium (GIK) solutions, and L-carnitine - have mechanisms of action distinct from traditional anti-ischemic drugs. These agents work by shifting myocardial energy metabolism away from fatty acids toward glucose as a source of fuel. Because these agents are well tolerated and do not affect heart rate or blood pressure, they conceivably could supplement traditional anti-ischemic drug therapy with little risk. The background, rationale for use, and published literature on each agent is reviewed, and the outcomes of pertinent clinical trials are discussed. In the case of ranolazine, data suggest benefit in the treatment of stable angina pectoris, particularly with sustained release formulations. Trimetazidine appears to have similar physiologic effects to ranolazine, and it is effective as monotherapy and as additive therapy in patients with chronic ischemic heart disease. DCA improves acidosis in critically ill patients and, likewise, improves myocardial hemodynamics in those with chronic coronary artery disease and congestive heart failure; however, its metabolism is variable and clinical data on its use in chronic ischemic heart disease are limited. GIK solutions have been shown to be beneficial in animal and human models of ischemia and acute myocardial infarction, and they offer an inexpensive means by which to improve the oxidation of glucose in the heart. Lastly, a large body of literature suggests a benefit with L-carnitine in a number of cardiovascular illnesses, including ischemic heart disease. Clinical trial data in acute myocardial infarction are promising and have prompted the initiation of a large-scale mortality trial.

MR spectroscopy study of dichloroacetate treatment after ischemic stroke

In a double-blind, placebo-controlled study, we used 1H MR spectroscopy to assess the effect of a single infusion of sodium dichloroacetate on lesion lactate 1 to 5 days after ischemic stroke. Apparent trends toward a reduction in lactate/N-acetyl compound ratios were seen at the higher drug doses employed, and in patients treated in the first 2 days following infarction. Use of spectroscopic measures as endpoints is feasible in acute stroke clinical trials.

Dichloroacetate improves postischemic function of hypertrophied rat hearts

OBJECTIVES

We sought to determine whether improving coupling between glucose oxidation and glycolysis by stimulating glucose oxidation during reperfusion enhances postischemic recovery of hypertrophied hearts.

BACKGROUND

Low rates of glucose oxidation and high glycolytic rates are associated with greater postischemic dysfunction of hypertrophied as compared with nonhypertrophied hearts.

METHODS

Heart function, glycolysis and glucose oxidation were measured in isolated working control and hypertrophied rat hearts for 30 min before 20 min of global, no-flow ischemia and during 60 min of reperfusion. Selected control and hypertrophied hearts received 1.0 mmol/liter dichloroacetate (DCA), an activator of pyruvate dehydrogenase, at the time of reperfusion to stimulate glucose oxidation.

RESULTS

In the absence of DCA, glycolysis was higher and glucose oxidation and recovery of function were lower in hypertrophied hearts than in control hearts during reperfusion. Dichloroacetate stimulated glucose oxidation during reperfusion approximately twofold in both groups, while significantly reducing glycolysis in hypertrophied hearts. It also improved function of both hypertrophied and control hearts. In the presence of DCA, recovery of function of hypertrophied hearts was comparable to or better than that of untreated control hearts.

CONCLUSIONS

Dichloroacetate, given at the time of reperfusion, normalizes postischemic function of hypertrophied rat hearts and improves coupling between glucose oxidation and glycolysis by increasing glucose oxidation and decreasing glycolysis. These findings support the hypothesis that low glucose oxidation rates and high glycolytic rates contribute to the exaggerated postischemic dysfunction of hypertrophied hearts.

Depletion of lactate by dichloroacetate reduces cardiac efficiency after hemorrhagic shock

We have demonstrated previously that dichloroacetate (DCA) treatment in rodents ameliorates, via activation of the pyruvate dehydrogenase complex, the cardiovascular depression observed after hemorrhagic shock. To explore the mechanism of this effect, we administered DCA in a large animal model of hemorrhagic shock. Mongrel hounds were anesthetized with 1.5% isoflurane and were measured for hemodynamics, myocardial contractility, and myocardial substrate utilization. They were hemorrhaged to a mean arterial pressure of 35 mm Hg for 90 min or until arterial lactate levels reached 7.0 mM (1137 +/- 47 mL or 49 +/- 2% total blood volume). Animals were chosen at random to receive DCA dissolved in water or an equal volume of saline at the onset of resuscitation. Two-thirds of the shed blood volume was returned immediately after giving an equivalent volume of saline. Two hours after the onset of resuscitation, mean arterial pressure was not different between DCA and control groups (79 +/- 3 vs. 82 +/- 3 mm Hg, respectively). Arterial lactate levels were significantly reduced by DCA (0.5 +/- 0.06 vs. 2.0 +/- 0.2 mM). However, DCA treatment was associated with a decreased stroke volume index (0.56 +/- 0.06 vs. 0.82 +/- 0.08 mL/kg/beat) and a decreased myocardial efficiency (19 vs. 41 L x mm Hg/mL/100 g tissue). During resuscitation by DCA, myocardial lactate consumption was reduced (21.4 +/- 3.7 vs. 70.7 +/- 16.3 micromole/min/100 g tissue) despite a three-fold increase in myocardial pyruvate dehydrogenase activity, while free fatty acid levels actually began to rise. Although increased lactate oxidation should be beneficial during resuscitation, we propose that DCA treatment led to a deprivation of myocardial lactate supply, which reduced net myocardial lactate oxidation, thus compromising myocardial function during resuscitation from hemorrhagic shock.

Lactic acidosis in the setting of antiretroviral therapy for the acquired immunodeficiency syndrome. A case report and review of the literature

Type B lactic acidosis, a rare but often fatal disorder, has been reported in 21 AIDS patients on antiretroviral therapy (ART). We present an AIDS patient with severe and prolonged lactic acidosis on stavudine and lamivudine. The lactic acidosis occurred in the absence of mitochondrial myopathy, hepatomegaly, or liver failure. This is the second report of lactic acidosis in a patient on stavudine and lamivudine. This patient recovered after aggressive supportive therapy including intravenous alkali and fluid administration as well as continuous venovenous hemodiafiltration. A single dose of dichloroacetate (DCA) was associated with a decrease in the serum lactate level by 20%, which persisted for more than 24 h. Seventeen months after recovery, the patient was rechallenged with ART without recurrence of lactic acidosis. We review and summarize all reported cases of patients with ART-associated lactic acidosis reported in the English literature.

Glucose and lactate kinetics in children with severe malaria

Children with severe malaria often present with lactic acidosis and hypoglycemia. Although both complications independently predict mortality, mechanisms underlying their development are poorly understood. To study these metabolic derangements we sequentially allocated 21 children with falciparum malaria and capillary lactate concentrations of 5 mmol/L or more to receive either quinine or artesunate as antimalarial therapy, and dichloroacetate or saline placebo for lactic acidosis. We then administered a primed infusion (90 min) of L-[3-13C1]sodium lactate and D-[6,6-D2]glucose to determine the kinetics of these substrates. The mean (SD) glucose disposal rate in all patients was 56 (16) micromol/kg x min, and the geometric mean (range) lactate disposal rate was 100 (66-177) micromol/kg x min. Glucose and lactate disposal rates were positively correlated (r = 0.62; P = 0.005). Artesunate was associated with faster parasite clearance, lower insulin/glucose ratios, and higher glucose disposal rates than quinine. Lactate disposal was positively correlated with plasma lactate concentrations (r = 0.66; P = 0.002) and time to recovery from coma (r = 0.82; P < 0.001; n = 15). Basal lactate disposal rates increased with dichloroacetate treatment. Elevated glucose turnover in severe malaria mainly results from enhanced anaerobic glycolysis. Quinine differs from artesunate in its effects on glucose kinetics. Increased lactate production is the most important determinant of lactic acidosis.

Proton magnetic resonance spectroscopy to study the metabolic changes in the brain of a patient with Leigh syndrome

Localized proton magnetic resonance spectroscopy (MRS) was performed to study the metabolic changes in the brain of a patient with Leigh syndrome, who had a T-->G point mutation at nt 8993 of mitochondrial DNA. In this patient, sodium dichloroacetate therapy normalized the lactate and pyruvate levels in both blood and cerebrospinal fluid (CSF). However, his psychomotor retardation did not improve and magnetic resonance imaging showed progressive cerebral atrophy. In the patient's spectra, elevation of brain lactate was observed throughout the brain with regional variations, predominantly in the basal ganglia and brainstem with an abnormal MRI appearance. Although the lactate/creatine ratio observed on proton-MRS was related to the CSF lactate level, the ratio did not completely parallel the CSF lactate level, i.e. brain lactate was detected even when the CSF lactate level had become normalized. Furthermore, proton-MRS revealed a decrease in the N-acetylaspartate/creatine ratio and an increase in the choline/creatine ratio, representing neuronal loss and breakdown of membrane phospholipids. The clinical and MRI findings were well related to the changes in spectroscopically determined brain metabolites. These results indicate that the brain metabolites observed on proton-MRS are useful indicators of a response to therapy and prognosis in Leigh syndrome.

A review of in vivo 1H magnetic resonance spectroscopy of cerebral ischemia in rats

A number of metabolic alterations are initiated by cerebral ischemia including dramatic increases in lactate concentration, decreases in N-acetylaspartate, choline, and creatine concentrations, as well as changes in amino acid levels. A review of proton nuclear magnetic resonance spectroscopy studies of focal and global cerebral ischemia in rats is presented here. In particular, studies in neonatal rats have shown that a continued elevation of lactate levels without recovery after hypoxia-ischemia or a decrease in N-acetylaspartate concentration at any time are indicative of deleterious outcome. Studies of the effect of temperature on ischemic damage in a model of focal ischemia showed that outcome improved with mild hypothermia. Again, lack of recovery of lactate upon reperfusion was shown to be indicative of poor outcome. Dichloroacetic acid was used to treat rats with focal ischemic damage. Animals subjected to transient ischemia that were treated with dichloroacetic acid showed significant decreases in lactate concentration.

Treatment of xanthelasma palpebrarum with bichloracetic acid

BACKGROUND

Although many treatment modalities have been described for xanthelasma palpebrarum, no single technique has emerged as dominant.

OBJECTIVES

Our purpose was to review the various therapeutic modalities for xanthelasma and to assess the efficacy of topical bichloracetic acid.

METHODS

Thirteen patients with 25 xanthelasma were treated with topical 100% bichloracetic acid. Efficacy was assessed over a follow-up period of 7 months to 10.5 years (average, 64 months).

RESULTS

Eighty-five percent of patients experienced initial complete clearing, and 72% of their lesions have not required retreatment over an average period of 68 months. Recurrences responded well to repeat treatment. Eighty-three percent of recurrent or poorly responsive lesions were associated with high cholesterol. The most resistant patient had four-lid involvement. Excellent cosmetic results and high patient satisfaction were seen.

CONCLUSIONS

Topical bichloracetic acid is a viable alternative to other modalities in the management of xanthelasma. Advantages include simplicity, cost-effectiveness, speed, safety, and efficacy.

[Lactate metabolism and lactic acidosis]

Lactate can be viewed as a metabolic dead end in that it can only be produced or utilized via pyruvate. Lactate production is determined primarily by pyruvate concentration and to a lesser extend by the redox state. Increased lactate production may result from tissue hypoxia, alkalosis, catecholamine and alanine transamination to pyruvate. Hyperlactatemia is observed in many pathological conditions. Current diagnostic criteria for lactic acidosis are a pH less than 7.35 and lactate concentration greater than 5 to 6 mmol/l. In our study series, malignancy was the most common underlying disease accompanied by lactic acidosis. Organ failure, cardiovascular disease and diabetes mellitus were also common. The prognosis of patients with these diseases were grave. In cases of lactic acidosis associated with diabetes mellitus, alcoholic liver disease, rhabdomyolysis and diabetic comas were noticeable as complications. Alcohol abuse was the most common cause of lactic acidosis associated with diabetes mellitus. In these cases, laboratory data showed prominent hyperlactatemia, hyperglycemia and acidemia and elevated anion gap. The mortality rate in these cases was 36% and higher in cases with organ failure. Treatment of lactic acidosis consists of alkalization by sodium bicarbonate with carbicarb, insulin-glucose-infusion, dichloroacetate therapy, tham administration, bicarbonate-buffered peritoneal dialysis and high bicarbonate-containing dialysis.

Magnetic resonance spectroscopy: use in monitoring MELAS treatment

BACKGROUND

Sodium dichloroacetate has been used to treat patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes (MELAS). Magnetic resonance spectroscopy (MRS) has been used to assess cerebral metabolism in MELAS, but to our knowledge, the findings of serial MRS studies performed after therapeutic intervention of strokelike episodes have not been reported.

METHODS

Proton MRS was serially used to measure brain metabolites in strokelike regions and in clinically uninvolved brain regions in a patient with MELAS.

PATIENT

A patient with MELAS and a strokelike episode clinically improved after treatment with sodium dichloroacetate. An elevated lactate-creatine ratio in the "stroke" region decreased on MRS studies after treatment. After a second episode, the lactate-creatine ratio increased from baseline in a region of the brain that was normal on magnetic resonance imaging scans.

CONCLUSIONS

To our knowledge, this is the first study to assess the response to treatment of a MELAS strokelike episode and the first to show an increase in the lactate-creatine ratio in a brain region that was associated with a clinical abnormality, even though it appeared normal on magnetic resonance imaging. We conclude that MRS may help to monitor therapeutic efficacy in mitochondrial encephalomyopathies.

Effects of dichloroacetate in three patients with MELAS

We present the clinical and laboratory effects of dichloroacetate (DCA) in three children with mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes (MELAS) who had not responded to other medications. Administration of DCA lowered the elevated levels of lactate and pyruvate in the serum and CSF. DCA ameliorated abdominal pain, headache, and strokelike episodes, and improved cognitive function and fatigability in the three patients during the study period. Some transient liver dysfunction, hypocalcemia, and peripheral neuropathy were observed. The use of DCA in MELAS merits further study.

Clinical and radiologic improvements in mitochondrial encephalomyelopathy following sodium dichloroacetate therapy

We administered sodium dichloroacetate (DCA), which reduces the circulating lactate and pyruvate concentrations by stimulating the activity of the pyruvate dehydrogenase complex (PDHC), to three children with mitochondrial encephalomyelopathy. Significant clinical, biochemical and radiologic improvements were obtained following DCA therapy (approximately 30 mg/kg per day, divided into three doses). All three patients had non-pyruvate dehydrogenase complex (PDHC) deficiencies: two exhibited Leigh syndrome (complex I deficiency and unknown etiology), and one abnormal myelination (multienzyme deficiency), demonstrated on magnetic resonance imaging (MRI). The lactic and pyruvic acid concentrations in serum and cerebrospinal fluid (CSF) were decreased significantly by the oral DCA treatment. The lactic acid peak on MR spectroscopy also markedly decreased in parallel with the CSF level. In addition, the brain lesions observed on MRI were improved in all patients. No exacerbation was observed in any of the patients, who have been followed-up more than 21 months following the DCA therapy. These results suggest that DCA therapy should be considered in all patients with a mitochondria-related enzyme deficiency.

Dichloroacetate as metabolic therapy for myocardial ischemia and failure

This article critically reviews the pharmacologic effects of the investigational drug dichloroacetate (DCA), which activates the mitochondrial pyruvate dehydrogenase enzyme complex in cardiac tissue and thus preferentially facilitates aerobic oxidation of carbohydrate over fatty acids. The pharmacologic effects of DCA are compared with other interventions, such as glucose plus insulin, inhibitors of long chain fatty acid oxidation and adenosine, that are also thought to exert their therapeutic effects by altering myocardial energy metabolism. Short-term clinical and laboratory experiments demonstrate that intravenous DCA rapidly stimulates pyruvate dehydrogenase enzyme complex activity and, therefore, aerobic glucose oxidation in myocardial cells. Typically these effects are associated with suppression of myocardial long chain fatty acid metabolism and increased left ventricular stroke work and cardiac output without changes in coronary blood flow or myocardial oxygen consumption. Although long-term studies are lacking, short-term parenteral administration of DCA appears to be safe and capable of significantly improving myocardial function in conditions of limited oxygen availability by increasing the efficient conversion of myocardial substrate fuels into energy.

Concomitant administration of sodium dichloroacetate and vitamin B1 for lactic acidemia in children with MELAS syndrome

Myoclonic seizures, intractable abdominal pain, and headaches resolved during the concomitant administration of sodium dichloroacetate and vita min B1 in two Japanese siblings with the MELAS syndrome (mitochondrial myopathy, encephalopathy, lactic acidosis and strokelike syndrome).

Pharmacokinetics of dichloroacetate in adult patients with lactic acidosis

The pharmacokinetic properties of the lactate-lowering drug dichloroacetate were investigated in 111 adult patients with lactic acidosis who were randomized to receive dichloroacetate as part of a placebo-controlled clinical trial. The clinical symptoms and etiology of lactic acidosis varied markedly among patients. Dichloroacetate, at a dose of 50 mg per kilogram of body weight, was administered in a 30-minute intravenous infusion into a peripheral vein. A second dose, identical to the first, was administered 2 hours after beginning the first infusion. Plasma levels of dichloroacetate were determined from blood samples collected periodically up to 288 hours after administration and the data were subjected to pharmacokinetic modeling. The pharmacokinetic properties of dichloroacetate in these acutely ill patients were complex and differed markedly from those in healthy volunteers, whose data fitted a one-compartment pharmacokinetic model. In contrast, the data from patients fitted one-, two-, or three-compartment pharmacokinetic models or even none of these, depending on the individual. Drug clearance in plasma tended to decrease as the number of compartments required to fit the data increased or as the number of drug treatments increased.

Dichloroacetate treatment in Leigh syndrome caused by mitochondrial DNA mutation

Sodium dichloroacetate (DCA) was administered to a 1-year-old female case of Leigh syndrome, who had a T > G point mutation at nt 8993 of mitochondrial DNA. Her biochemical and clinical symptoms improved gradually, but proton magnetic resonance spectroscopy revealed reduction of the N-acetylaspartate/creatine ratio, and magnetic resonance imaging showed progressive cerebral atrophy despite the DCA therapy. These results suggest that DCA therapy may not retard the progress of the primary disease in Leigh syndrome, but produced clinical improvement most likely by reducing toxic accumulation of lactate.

Effect of hypothermia, dichloroacetate, and deferoxamine in the treatment for cortical edema and functional recovery after experimental cortical impact in the rat

OBJECTIVE

To investigate the effects of hypothermia alone or in combination with dichloroacetic acid (DCA) and/or deferoxamine (DFO) in reducing cortical edema (CE) and improving neurologic functional recovery after moderate closed and head trauma with controlled cortical impact (CCI).

METHODS

Anesthetized rats were randomized to receive right parietal moderate CCI (impact depth 2 mm, speed 3.5 m/sec) or sham operations. Immediately after trauma, the animals underwent selective brain cooling to 30 degrees C (temporalis muscle temperatures). Ten minutes after trauma, the randomized animals received intraperitoneal doses of DCA (25 mg/kg), DFO (50 mg/kg), both DCA and DFO, or equivolume normal saline. For evaluation of cortical edema, some animals (n = 42) were sacrificed 4 hours after trauma and cortical specific gravity (SpG) was determined gravimetrically. The other animals (n = 47) were evaluated for functional recovery beginning 6 days posttrauma. Neurobehavioral performance was assessed in the Morris water maze.

RESULTS

Cortical edema was significantly less in the animals treated with hypothermia (SpG = 1.041 +/- 0.001, p < 0.05) compared with the untreated traumatized animals (SpG = 1.037 +/- 0.001). Combination treatment with hypothermia and drug treatment did not reduce cortical edema when compared with no treatment. Hypothermia with and without drug treatment did not improve neurobehavioral performance when compared with no treatment.

CONCLUSIONS

In this pilot study with a relatively small sample size, hypothermia alone significantly reduced post-CCI cortical edema as measured by SpG. Hypothermia combined with drug treatment did not reduce posttraumatic cortical edema. Hypothermia with and without drug therapy did not improve functional neurologic recovery in the rats subjected to CCI.

Combined aerobic training and dichloroacetate improve exercise capacity and indices of aerobic metabolism in muscle cytochrome oxidase deficiency

There is no generally effective therapy for mitochondrial myopathies. In this study, we measured responses to combined aerobic training and oral dichloroacetate (DCA) therapy in a 25-year-old woman with a mitochondrial myopathy caused by cytochrome oxidase deficiency. The patient trained for 14 weeks, and DCA therapy was begun after 8 weeks. Independent indices of aerobic capacity and oxidative metabolism showed substantial improvement. Venous lactate concentrations at rest, and after a constant amount of work, decreased by approximately 50% after 8 weeks of aerobic training, and by more than 70% with the combination of training and DCA treatment. Heart rate at rest and after a constant amount of submaximal work decreased progressively. Aerobic capacity on a graded submaximal exercise test improved by 71% from baseline by the end of the treatment period. 31P magnetic resonance spectroscopy measurements of rate constants for recovery of muscle phosphocreatine increased 1.7-fold and metabolically active adenine diphosphate increased 2.8-fold after 8 weeks of training alone, and 4.5-fold and 23.0-fold after 14 weeks of training plus DCA treatment. Responses to the SF-36 Health Survey suggested a marked reduction in handicap. Thus, in this open study of a patient with cytochrome oxidase deficiency, a combination of aerobic training and DCA treatment resulted in substantial improvements in biochemical indices, exercise performance, and handicap. We conclude that exercise limitation in patients with mitochondrial myopathy may arise from effects of chronic deconditioning in addition to the effects of primary mitochondrial dysfunction and may be partially reversed by training and administration of DCA.

Oxidative phosphorylation defect associated with primary adrenal insufficiency

An 18-month-old girl with an oxidative phosphorylation defect had neonatal onset of chronic lactic acidosis, lipid storage myopathy, bilateral cataracts, and primary adrenal insufficiency. Chronic lactic acidosis responded to treatment with dichloroacetate. Sequential muscle biopsies demonstrated resolution of the lipid storage myopathy associated with the return to normal muscle free carnitine levels. This case demonstrates a new clinical phenotype associated with a defect in oxidative phosphorylation and the need to consider mitochondrial disorders in the differential diagnosis of primary adrenal insufficiency in childhood.

Protective effect of dichloroacetate in a rat model of forebrain ischemia

Dichloroacetate (DCA) activates the pyruvate dehydrogenase complex (PDHC), and improves the recovery of cerebral pH, lactate, ATP, and PCr following reperfusion in animal models of forebrain ischemia. In order to determine whether this results in neuroprotection, rats were administered NaDCA (100 mg/kg or 10mg/kg i.v.) 10 min before 12 min of normothermic forebrain ischemia (bilateral carotid artery occlusion plus systemic hypotension, 45 mmHg). Neuronal injury assessed histopathologically 7 days post-ischemia was significantly reduced in the CA1 region of the hippocampus, the dorsal lateral striatum, and the neocortex, in rats treated with 100 mg/kg NaDCA, but not in rats treated with 10 mg/kg NaDCA.

Pyruvate dehydrogenase inactivity is not responsible for sepsis-induced insulin resistance

OBJECTIVE

To determine whether activation of pyruvate dehydrogenase with dichloroacetate can reverse sepsis-induced insulin resistance in humans or rats.

DESIGN

Prospective, controlled study.

SETTING

Intensive care unit (ICU) and laboratory at a university medical center.

SUBJECTS

Nine patients were admitted to the ICU with Gram-negative sepsis, confirmed by cultures. In addition, chronically instrumented, Sprague-Dawley rats, either controls or with live Escherichia coli-induced sepsis.

INTERVENTIONS

Hyperinsulinemic euglycemic clamp, with or without coadministration of dichloroacetate.

MEASUREMENTS AND MAIN RESULTS

In humans, a primed, constant infusion of [6,6-2H2]glucose was used to determine endogenous glucose production and whole-body glucose disposal. Septic humans exhibited impaired maximal insulin-stimulated glucose utilization (39.5 +/- 2.7 mumol/kg/min), despite complete suppression of endogenous glucose production. In rats, a primed, constant infusion of [3-3H]glucose was used to determine endogenous glucose production and whole-body glucose disposal. Tissue glucose uptake in vivo was determined by [14C]-2-deoxyglucose uptake. Maximal, whole-body, insulin-stimulated glucose utilization was 205 +/- 11 and 146 +/- 9 mumol/kg/min in control and septic rats, respectively. The defect was specific to skeletal muscle and heart. Stimulation of pyruvate dehydrogenase with dichloroacetate caused a 50% decrease in plasma lactate concentration but failed to improve whole-body insulin-stimulated glucose utilization in either the septic human or rat. Dichloroacetate reversed the impairment of insulin-stimulated myocardial glucose uptake in septic rats, but did not influence skeletal muscle glucose uptake either under basal conditions or during insulin stimulation.

CONCLUSIONS

Activation of pyruvate dehydrogenase with dichloroacetate does not ameliorate the impairment of whole-body, insulin-stimulated glucose uptake in septic humans or rats, or reverse the specific defect in insulin-mediated skeletal muscle glucose uptake by septic rats. Therefore, the decreased pyruvate dehydrogenase activity associated with sepsis does not appear to mediate sepsis-induced insulin resistance during insulin-stimulated glucose uptake at either the whole-body or tissue level.

In vivo metabolic response of glucose to dichloroacetate in humans

Hyperglycemia is common in severely ill patients and is related principally to an increase in glucose production. Dichloroacetate (DCA), which is known to increase the rate of pyruvate oxidation, has been shown to lower plasma glucose concentrations in normal fasting subjects and in diabetics and thus may be efficacious in treating stress induced hyperglycemia. However, the mechanism by which DCA lowers the plasma glucose concentration in humans has not been elucidated. To examine the human in vivo metabolic alterations induced by DCA, six fasting volunteers were infused with 6,6-D2-glucose and indirect calorimetry was performed prior to and following DCA administration. Glucose, lactate, and alanine net balance across the leg were also quantitated. Following DCA administration, plasma glucose concentrations decreased by 9% due to a proportional decrease in the rate of glucose production (P < 0.05). DCA had no affect on glucose clearance or leg net balance; however, the rate of glucose oxidation increased by 24% from baseline (P < 0.05). This increase in glucose oxidation without a compensatory change in peripheral glucose consumption suggests an improved efficiency in peripheral glucose utilization induced by DCA. Plasma concentrations of lactate and alanine were also lowered by DCA (56% for lactate, 66% for alanine, P < 0.05) without a significant alteration in leg net balance. These results suggest that DCA may decrease gluconeogenesis by limiting the availability of the precursor substrates lactate and alanine. Thus dichloroacetate may be an appropriate alternative to insulin in correcting mild elevations in plasma glucose concentrations. Furthermore, DCA may be especially effective in severely ill patients where hyperglycemia is largely due to increases in gluconeogenesis.

The disposition and effects of two doses of dichloroacetate in adults with severe falciparum malaria

1 Dichloroacetate (DCA) is a promising treatment for lactic acidosis complicating severe malaria. The pharmacokinetics, pharmacodynamics and toxicity of dichloroacetate were evaluated in 11 patients with severe malaria, and their lactate responses compared with nine control patients in an open-label prospective study. 2 Intravenous DCA (46 mg kg-1 infused in 30 min) or saline placebo was given on admission to the study, and 12 h later, as an adjunct to standard quinine treatment. 3 An open one-compartment model with the following parameters described the pharmacokinetics of DCA after one dose (mean [s.d.]): V = 0.44(0.2) 1 kg-1; CL = 0.13 [0.027] 1 h-1 kg-1; Cmax = 106[28] mg1-1; t1/2 = 3.4(2.2) h. After two doses of DCA (n = 9) the pharmacokinetic parameters were similar to those after the first dose. 4 DCA decreased venous plasma lactate concentrations by 42% of baseline values 8 h after admission, normalized arterial pH from a mean(s.d.) of 7.367(0.063) to 7.39(0.1), and decreased the calculated base deficit from 9.2(7.3) mEq 1-1 to 6.4(10.4) mEq 1-1. In control patients lactate concentrations fell by approximately 14% of baseline concentrations (P < 0.02 compared with DCA recipients). Venous lactate concentrations fell a further 16% from baseline values after the second dose of DCA but this change was not significantly different from controls. There was no electrocardiographic or other evidence of toxicity associated with DCA. 5 These data suggest that a single intravenous infusion of DCA rapidly reduces hyperlactataemia in patients severely ill with malaria, and that DCA should be evaluated further as an adjunct to conventional antimalarial and supportive measures for such patients with lactic acidosis.

Therapeutic efficacy of a case of pyruvate dehydrogenase complex deficiency monitored by localized proton magnetic resonance spectroscopy

We experienced a case of pyruvate dehydrogenase deficiency observed by proton magnetic resonance spectroscopy (1H MRS). This case was diagnosed as West syndrome by characteristic convulsion and the periodic hypsarrhythmia pattern of EEG. At the age of 11 months, the first examination of 1H MRS revealed a high peak of lactate, and the high concentration of lactate and pyruvate was confirmed in sampled cerebrospinal fluid (CSF). Deficiency of pyruvate dehydrogenase complex was finally diagnosed by genetic examination. Dichloroacetate was administered to the patient as therapy. Decrease of lactate in the brain was found by 1H MRS. Lactate and pyruvate in the CSF was also decreased. In accordance with the suspension of dichloroacetate, increase of lactate in the brain was detected and the convulsions reappeared. After readministration of dichloroacetate, the patient was almost symptom free and lactate in the brain and CSF had decreased to the normal extent. We considered that 1H MRS provides useful information for screening metabolic disorders of infants and assessing the efficacy of therapy.

Effects of chemical pretreatment on posttraumatic cortical edema in the rat

The purpose of this study was to evaluate the effects of mannitol (Man), dexamethasone (DM), dichloroacetic acid (DCA) and 1,3-butanediol (BD) in reduction of posttraumatic cortical edema following brain deformation injury to rats. Ten minutes prior to fluid percussion injury, each animal received one of four pretreatments or placebo: Man, 1 g/kg intravenously, DM 3.0 mg/kg intravenously, DCA 25 mg/kg intraperitoneally BD 0.5 mg/kg intraperitoneally (n = 12 per treatment group), or equivolume saline (n = 8 per corresponding trauma group). Six hours after trauma, cortical tissue was harvested. Using a benzene-kerosene gradient column calibrated with potassium sulfate standards, the specific gravity (SpG) of cortical tissue from each group was measured and compared (ANOVA, P < .05). The measured cortical SpG from traumatized animals receiving Man (mean 1.037 +/- SEM .001), DCA (1.038 +/- .001), and BD (1.039 +/- .001) were equal to SpG from untraumitized cortex (1.041 +/- .001), and were significantly greater than SpG from traumatized cortex for animals receiving DM (1.035 +/- .001) or placebo (1.033 +/- .002). Pretreatment with DCA, Man, and BD appears to protect against development of posttraumatic cortical edema when measured 6 hours after blunt head trauma in the rat. Each of these chemical treatments appears effective in preventing or reducing posttraumatic cortical edema.

Leigh disease with deficiency of lipoamide dehydrogenase: treatment failure with dichloroacetate

A 6-month-old female infant with hypotonia and keto and lactic acidosis was diagnosed with lipoamide dehydrogenase (E3) deficiency. This enzyme is a component of the pyruvate, alpha-ketoglutarate, and branched chain alpha-ketoacid dehydrogenase complexes. At the time of diagnosis her plasma contained elevated branched chain amino acids, alanine, alloisoleucine, ketones, pyruvate, and lactate, and her urine contained elevated branched chain ketoacids and lactate. By neuroimaging she was found to have Leigh subacute necrotizing encephalomyelopathy. Modest branched-chain amino acid restriction led to the disappearance of alloisoleucine and normalization of her branched chain amino acid values, while institution of a high fat diet precipitated hypoglycemia and acidosis. A trial of lipoic acid led to a transient modest improvement in her lactic acidemia. Use of dichloroacetate to activate the pyruvate dehydrogenase complex led to a significant decline in lactate levels, but this was also transient. The patient had significant growth failure despite a high carbohydrate, high calorie diet, yet remained clinically well until 28 months of age when she developed acute acidosis and brainstem dysfunction and died.

[Medicinal therapy for lysosomal storage diseases]

Lysosomes contain several dozen different enzymes, mostly acid hydrolases. Materials not digested due to deficient lysosomal enzymes are usually large cellular molecules, which are deposited within the cells. The strategy for medicinal therapy of lysosomal storages disease may be to develop the activators of enzymes, to promote coenzyme and cofactor supplementation and to eliminate undegraded materials from blood into urine. In the last several decades, many trials for these strategies has been done. Cysteamine for cystinosis and penicillamine for Wilson's disease has proved useful in treating these patients. Recently, DMSO has been proved to be an activator of acid sphingomyelinase and to accelerate the intracellular mobilization of LDL-derived cholesterol. We treated patients with Niemann-Pick disease type C by oral administration of DMSO, resulting in some clinical benefits such as decreased size of hepatosplenomegaly, and lesser frequency of seizures with improved EEG. However, the progressive clinical course has not been changed although it appeared to slow down. New activators of lysosomal enzymes should be developed for medicinal therapy of lysosomal storage diseases.

The therapy of respiratory chain encephalomyopathy: a critical review of the past and current perspective

The mitochondrial respiratory chain encephalomyopathies represent an important group of multisystem disorders. No curative treatment is currently available. A number of measures have been reported to have a theoretical potential to improve respiratory function. These treatment strategies have variable scientific support, many reports being anecdotal. We critically review the various therapeutic measures employed and suggest future treatment directions.

Autogenous vaccine: the best therapy for perianal condyloma acuminata?

PURPOSE

Treatment of perianal condyloma acuminata is frustrating because most treatment options are fraught with high recurrence rates and patient discomfort. We propose that surgical excision followed by vaccination with an autogenous condyloma acuminata vaccine is the most effective therapy available in primary and recurrent perianal condyloma acuminata.

METHODS

Eighty-three patients with perianal condyloma acuminata were treated from 1985 to 1992. Treatment was divided for patients as follows: surgical excision, 20; bichloroacetic acid, 10; podophyllin and interferon A, 5; excision followed by autogenous condyloma acuminata vaccination twice weekly using 0.1 ml subcutaneously for three weeks increasing to 1.0 ml subcutaneously for seven weeks, 43. Syphilis was diagnosed in seven patients; two were human immunovirus-positive. All but three patients were male. Of those patients treated with the vaccination protocol, 25 had primary and 18 had recurrent disease.

RESULTS

Recurrence rates were: excision alone and bichloroacetic acid, 50 percent; podophyllin and interferon A, 85 percent; whereas only 4.6 percent recurred when treated with excision and vaccination. Mean follow-up was 13 (range, 6-23) months. All patients treated with the vaccination protocol tolerated the full course of therapy.

CONCLUSION

We believe that excision of perianal condyloma acuminata followed by autogenous condyloma acuminata vaccination for approximately ten weeks is the most effective and definitive treatment option and, moreover, should be considered in all patients with perianal condyloma acuminata.