Multiple respiratory chain abnormalities associated with hypertrophic cardiomyopathy and 3-methylglutaconic aciduria.

In a 4.5-month-old boy presenting with marked muscular hypotonia in the neonatal period, hepatomegaly, cardiac hypertrophy, recurrent hypoglycemia, metabolic acidosis, and secondary carnitine deficiency, there was a considerable urinary excretion of 3-methylglutaconic and 3-methylglutaric acid. Estimation of 3-methylglutaconyl-CoA hydratase, 3-hydroxy-3-methylglutaryl-CoA lyase and initial enzymatic steps of cholesterol biosynthesis in cultured fibroblasts and in different tissues postmortem revealed no enzyme deficiency. Analyses of the respiratory chain in postmortem tissues demonstrated severe impairment of complex I (NADH ubiquinone oxidoreductase) and complex IV (cytochrome c oxidase) activities in skeletal muscle and reduced complex IV activity in heart.

Hartnup syndrome, progressive encephalopathy and allo-albuminaemia. A clinico-pathological case study.

Clinical, biochemical, neuropathological and neurochemical findings in a case of Hartnup syndrome are reported. After initially normal development, the affected girl suffered progressive neuropsychiatric decline with statomotor and mental retardation and intractable seizures and died at the age of 2 years. Postmortem neuropathological and neurochemical investigations showed a combination of extensive neuronal degeneration and cerebral dysmyelination. Pathogenetic hypotheses and the relationship between neuropsychiatric disease and Hartnup syndrome are discussed. Additionally, a fast type bisalbuminaemia present in the girl and her mother is described.

Colour Doppler imaging of intracranial vasculopathy in severe infantile sialidosis.

Neonatal ascites is usually attributed to prenatal infections, lysosomal storage disease and anomalies of the genitourinary tract, gastrointestinal tract or cardiovascular system. We report one case of neonatal ascites associated with infantile sialidosis. Cerebral sonography showed stripe-like intracerebral echogenicities in the region of the basal ganglia. Colour Doppler imaging demonstrated blood flow within the echogenicities confirming the suspected diagnosis of intracranial vasculopathy.

Fatal infantile mitochondrial cardiomyopathy and myopathy with heterogeneous tissue expression of combined respiratory chain deficiencies.

A 5-month-old boy died of progressive heart failure that started at the age of 3 months. Autopsy revealed a mitochondrial cardiomyopathy and a mitochondrial myopathy of the limb muscle and diaphragm. Cytochemically random defects of cytochrome c oxidase were visualized by light and electron microscopy in the diaphragm and especially the heart muscle, the limb muscle showing a diffuse attenuation whereas the liver and kidneys reacted normally. The activities of NADH-dehydrogenase (complex I) and cytochrome c oxidase (complex IV) were severely diminished (20% residual activity of controls) in the skeletal and heart muscle. In the heart, succinate cytochrome c reductase (complex II/III) was additionally decreased to the same degree. Loss of cytochrome c oxidase activity was based on a reduction of both mitochondrial and nuclear derived subunits in the heart and diaphragm as revealed by immunohistochemical analysis, whereas the limb muscle showed a normal immunoreactive protein content. The results illustrate heterogeneous tissue expression of respiratory chain enzyme defects and demonstrate that a cardiomyopathy may be the leading presentation of a mitochondrial disorder in early infancy.

Beta-adrenergic agonists stimulate the oxidative pentose phosphate pathway in the rat heart.

The oxidative pentose phosphate pathway is poorly developed in the rat heart compared with other organs, since the activity of glucose-6-phosphate dehydrogenase (G-6-PDH), the first and rate-limiting enzyme of the oxidative pentose phosphate pathway, is low. As a consequence, the available pool of 5-phosphoribosyl-1-pyrophosphate and the rate of adenine nucleotide biosynthesis are limited. Isoproterenol, 24 hours after subcutaneous administration at 0.1, 1, and 25 mg/kg, stimulated the activity of G-6-PDH in whole hearts dose-dependently from 4.3 +/- 0.16 (control) to 6.6 +/- 0.35, 10.3 +/- 0.82, and 11.5 +/- 0.56 units/g protein, respectively. The activity of 6-phosphogluconate dehydrogenase, another of the enzymes in the oxidative pentose phosphate pathway, remained unchanged. G-6-PDH activity started to increase 12 hours after isoproterenol application, when the glycogenolytic and functional response was over, and reached a peak value between 24 and 48 hours. This stimulating effect was also demonstrated in cardiac myocytes that were isolated 28 hours after isoproterenol application. beta-receptor blockade with atenolol reduced the isoproterenol-induced increase in cardiac G-6-PDH activity by 90%. Cycloheximide, which inhibits translation, and actinomycin D, which interferes with transcription, attenuated it by 83% and 78%, respectively. These results indicate that cardiac beta-adrenergic receptors and enzyme protein synthesis are involved in this effect. Other beta-sympathomimetic agents such as dopamine, dobutamine, fenoterol, salbutamol, and terbutaline also stimulated myocardial G-6-PDH activity in a time- and dose-related manner. The calcium antagonist D 600 (gallopamil) reduced the isoproterenol-elicited stimulation by 65%, and verapamil blunted the fenoterol-induced increase by 50%. This suggests that Ca2+ ions also contribute to the stimulation of the cardiac oxidative pentose phosphate pathway.

[D-penicillamine-induced IgA deficiency in the therapy of Wilson's disease]. / D-Penicillamin-induzierter IgA-Mangel bei der Therapie der Wilsonschen Erkrankung.

Serum IgA deficiency was first noted in a 10 year old boy 8 months after the onset of D-penicillamine therapy. Special immunological examinations revealed a deficiency of the secretory component of IgA while cellular functions of T- and B-lymphocytes were normal. The patient showed discrete clinical signs compatible with IgA deficiency. Regular control of patients with Morbus Wilson and D-penicillamine treatment should include measurement of serum immunoglobulin levels.

Report on a new patient with combined deficiencies of sulphite oxidase and xanthine dehydrogenase due to molybdenum cofactor deficiency.

A newborn infant exhibiting seizures and spastic tetraparesis at the age of 1 week was shown to excrete excessive quantities of sulphite, taurine, S-sulphocysteine and thiosulphate, characteristic of sulphite oxidase deficiency. In addition, increased renal excretion of xanthine and hypoxanthine combined with a low serum and urinary uric acid was consistent with xanthine dehydrogenase deficiency. Both deficiencies could be established at the enzyme level. The primary defect giving rise to the combined abnormalities is the absence of a molybdenum cofactor, a molybdenum-containing pterin being an essential component of both enzymes. The patient developed a severe neurological syndrome, brain atrophy and lens dislocation and died at the age of 22 months. Attempts at treatment, such as oral administration of ammonium molybdate, sodium sulphate, D-penicillamine, 2-mercaptoethane sulphonic acid, pyridoxine and thiamine did not influence the clinical course.

[Fructose-1,6-diphosphatase deficiency. Clinical aspects and diagnosis based on a case report]. / Fruktose-1,6-Diphosphatasemangel. Klinik und Diagnosestellung anhand eines Fallbeispieles.

In a 2-year-old boy the enzyme defect of fructose-1,6-diphosphatase deficiency could be demonstrated in liver tissue, jejunal mucosa and leukocytes. During the neonatal period the boy had suffered from transient metabolic acidosis and hypoglycemia. At the age of 2 years, during a febrile infection, he developed a hyperkinetic-hypotonic syndrome, which disappeared by fructose-free diet and avoidance of prolonged periods of fasting.

Metabolic recovery following temporary regional myocardial ischemia in the rat.

The restoration of the cardiac ATP content after an ischemic insult takes a long period of time. Ribose, via stimulation of adenine nucleotide biosynthesis, accelerated the replenishment of the adenine nucleotide pool in the heart, in the kidney, however, it had no effect. In the myocardium, the ribose-mediated restoration of the adenine nucleotide content was dependent on the duration of the previous ischemic period and was not influenced by the beta-receptor blocker atenolol.

Ribose accelerates the repletion of the ATP pool during recovery from reversible ischemia of the rat myocardium.

It is a characteristic feature of the myocardium that the derangement in function [6] and the depletion of the ATP pool [1, 2, 9] that occur subsequent to oxygen deficiency persist when blood flow is restored. Of renewed interest is the inability of the heart to replenish rapidly its adenine nucleotide pool once it has been diminished during a brief period of regional ischemia [2, 9]. A hypothesis that could explain this metabolic insufficiency of the myocardium is that the biosynthesis of adenine nucleotides is very slow in the normal heart and is increased only moderately during postischemic recovery [15] so that the replenishment of adenine nucleotides is not affected appreciably. To substantiate such a hypothesis it is necessary to provide evidence that the restitution of the ATP pool can be accelerated by stimulation of this biosynthetic process. In previous studies ribose has been recognized as a substrate that enhances markedly adenine nucleotide biosynthesis in the rat heart [11, 12]. We now demonstrate that continuous i.v. infusion of ribose during recovery from a 15-min period of myocardial ischemia in rats leads to restoration of the cardiac ATP pool within 12 h, whereas 72 h are needed for ATP normalization without any intervention.

Ribose intervention in the cardiac pentose phosphate pathway is not species-specific.

Ribose is cardioprotective in the rat in a variety of pathophysiological conditions. The metabolic basis for this effect is the low capacity of the oxidative pentose phosphate pathway in the myocardium. Ribose bypasses this pathway, elevates the available pool of 5-phosphoribosyl-l-pyrophosphate, and thus stimulates the biosynthesis of adenine nucleotides. In this study reported here the activity of glucose-6-phosphate dehydrogenase, the first and rate-limiting enzyme of the oxidative pentose phosphate shunt, was very low in the human heart and was of the same order of magnitude in the myocardium of various animal species. Furthermore, ribose had a similar stimulating effect on myocardial adenine nucleotide biosynthesis in the guinea pig, in which hemodynamic parameters are different from those in the rat. It is concluded that the metabolic basis for the effectiveness of ribose is similar in all species investigated.

Effects of ribose on cardiac metabolism and function in isoproterenol-treated rats.

Continuous iv infusion of ribose for 5 h in unanesthetized and unrestrained rats treated with isoproterenol (25 mg/kg sc) further enhanced the available pool of 5-phosphoribosyl-1-pyrophosphate and the biosynthesis of adenine nucleotides in the myocardium. The increase in adenine nucleotide biosynthesis was of such an extent that the isoproterenol-induced decline of the ATP level (mumol/g) was attenuated after 5 h (isoproterenol + ribose infusion 4.0 +/- 0.2, n = 10; isoproterenol + NaCl infusion 3.5 +/- 0.1, n = 23; control 4.5 + 0.1, n = 38) and prevented after 24 h (isoproterenol + ribose infusion 4.6 +/- 0.3, n = 5; isoproterenol + NaCl infusion 3.2 +/- 0.1, n = 9). Ribose, however, did not affect the isoproterenol-elicited elevation of the adenosine 3',5'-cyclic monophosphate (cAMP) and glucose 6-phosphate content nor did it influence the decline in glycogen. Thus ribose acts primarily via elevation of the cardiac 5-phosphoribosyl-1-pyrophosphate pool. Measurements of hemodynamic parameters with an ultraminiature catheter pressure transducer in intact rats anesthetized with thiobutabarbital sodium revealed that ribose infusion for at least 3 h further enhanced the isoproterenol-elicited increase in left ventricular dP/dtmax by about 20% but did not influence appreciably the rise in heart rate and the fall in left ventricular systolic pressure. Since ribose did not affect the immediate hemodynamic alterations induced by isoproterenol, it appears that it exerts its hemodynamic effects via the pronounced influence on cardiac adenine nucleotide metabolism.

Possible role of oxidized glutathione for the regulation of the myocardial hexose monophosphate shunt.

Infusion of the isolated perfused Langendorff rat heart with tert-butyl hydroperoxide (3 X 10(-4) M) resulted in a marked enhancement of the concentration of oxidized glutathione, in an increase of the NADP+/NADPH ratio, and in an elevation of the available pool of 5-phosphoribosyl-1-pyrophosphate, which is one of the end products of the hexose monophosphate shunt. Since it has been shown that oxidized glutathione overcomes the inhibition of glucose-6-phosphate dehydrogenase exerted by NADPH, these results suggest that the myocardial hexose monophosphate shunt can be stimulated rapidly and markedly through this control mechanism.

Reduction of the isoproterenol-induced alterations in cardiac adenine nucleotides and morphology by ribose.

Continuous intravenous infusion of ribose (200 milligrams per kilogram per hour) for 24 hours induced a marked stimulation of cardiac adenine nucleotide biosynthesis in unanesthetized and unrestrained rats that had been treated with isoproterenol subcutaneously (25 milligrams per kilogram). The diminution of adenine nucleotides characteristic for the action of high doses of isoproterenol was entirely prevented, and the incidence of the isoproterenol-induced myocardial cell damage was significantly reduced when ribose was administered. These results support the view that depletion of adenine nucleotides is involved in the development of cardiac necrosis.

Isoproterenol-induced enhancement of myocardial glucose-6-phosphate dehydrogenase.

Isoproterenol enhanced the activity of glucose-6-phosphate dehydrogenase and the availability of 5-phosphoribosyl-1-pyrophosphate in the rat myocardium, which indicates an increased flow through the hexose monophosphate shunt. The stimulatory effect of isoproterenol on cardiac glucose-6-phosphate dehydrogenase activity, could be prevented by beta-receptor blockade with atenolol, but not by the calcium-antagonistic compound D 600.

Significance of the hexose monophosphate shunt in experimentally induced cardiac hypertrophy.

1. In three models of cardiac hypertrophy in rats (aortic constriction, application of a single dose of isoproterenol and daily injections of triiodothyronine) the biosynthesis of myocardial adenine nucleotides was enhanced. 2. In hypertrophying hearts due to aortic constriction and isoproterenol application, the activity of glucose-6-phosphate dehydrogenase and the available pool of 5-phosphoribosyl-1-pyrophosphate were increased indicating a stimulation of the hexose monophosphate shunt. In triiodothyronine-treated animals only the cardiac pool of 5-phosphoribosyl-1-pyrophosphate turned out to be elevated. 3. In all three models of cardiac hypertrophy, the enhancement of myocardial adenine nucleotide biosynthesis was exaggerated by ribose. It thus appears that the 5-phosphoribosyl-1-pyrophosphate pool is the limiting factor for the increase of adenine nucleotide biosynthesis under these conditions. 4. Long-term i.v. infusion of ribose (200 mg/kg/h) in isoproterenol-treated rats prevented the decrease of the cardiac ATP concentration induced by isoproterenol. However, the isoproterenol-induced stimulation of total cardiac protein synthesis was not altered, suggesting that the ATP decline may not be the trigger for stimulating protein synthesis in this model of myocardial hypertrophy.