Maple syrup urine disease (MSUD)--clinical profile of 47 Filipino patients.

Maple syrup urine disease (MSUD) is a very rare disorder of branched-chain amino acid metabolism. However, it is the most common inborn error of metabolism in the Philippines. We present a retrospective review of 21 patients diagnosed with MSUD between 1999 and 2004. The patients presented clinically between 2 and 14 days of life (mean 5 days) and the diagnosis of MSUD was established between 6 days and 11 months of age (mean 39 days). The classical burnt sugar odour was noted in the majority of patients (81%). The diagnosis of MSUD was initially based on clinical suspicion and confirmed biochemically by measurement of leucine/isoleucine levels by thin-layer chromatography. The acute management included removal of accumulated branched-chain amino acids by peritoneal dialysis in 62% of the patients. Mortality rate of this group of patients was 24% and follow-up rate was 87%. We compared this series with a previously reported series of 26 patients to determine whether diagnosis and the management of MSUD improved over the two periods. Four cases have been diagnosed early since 1992, the majority of whom had the classic form of MSUD with the onset of symptoms in the first two weeks of life. A small subset of patients with early nonspecific symptoms was diagnosed much later owing to a low-level clinical suspicion among clinicians. Overall, however, there appears to be a small but general trend towards earlier diagnosis, reduced mortality and long-term follow up in the later series. Although we are able to diagnose and manage MSUD in the Philippines, we recognize that the clinical outcome remains poor and is due mainly to late referral of cases and inadequate long-term management. In the Philippines, we recommend that all newborns who are considered to be septic, have feeding difficulties, fail to regain their birth weight or present with any other symptoms suggestive of MSUD be evaluated in the first instance by analysis of urine for ketones and if they are positive have blood collected and sent to our laboratory for leucine/isoleucine measurement.

Transient multiple acyl-CoA dehydrogenation deficiency in a newborn female caused by maternal riboflavin deficiency.

A newborn female presented on the first day of life with clinical and biochemical findings consistent with multiple acyl-CoA dehydrogenase deficiency (MADD). Riboflavin supplementation corrected the biochemical abnormalities 24 h after commencing the vitamin. In vitro acylcarnitine profiling in intact fibroblasts both in normal and riboflavin depleted media showed normal oxidation of fatty acids excluding defects in electron transfer flavoprotein (ETF), or ETF ubiquinone oxidoreductase (ETF:QO), or a genetic abnormality in flavin metabolism. In addition, sequencing of the genes encoding ETF and ETF:QO in the proband did not reveal any pathogenic mutations. Determination of the maternal riboflavin status after delivery showed that the mother was riboflavin deficient. Repeat testing done two years after the infant's birth and while on a normal diet showed that the mother was persistently riboflavin deficient and showed a typical MADD profile on plasma acylcarnitine testing. A possible genetic defect in riboflavin transport of metabolism in the mother is postulated to be the cause of the transient MADD seen in the infant. Sequencing of the SLC16A12, RFK and FLAD1 genes encoding key enzymes in riboflavin transport of metabolism in the mother did not identify any pathogenic mutations. The underlying molecular basis of the mother's defect in riboflavin metabolism remains to be established.

Low citrulline may not be diagnostic of ornithine transcarbamylase deficiency: a case report.

A newborn boy with family history of severe ornithine transcarbamylase (OTC) deficiency was investigated prospectively and managed aggressively at birth based on an existing protocol for at risk neonates. Undetectable citrulline levels at birth suggested that the infant was affected; however, normal plasma glutamine and urine orotic acid levels confused the diagnosis to some extent. Mutation testing confirmed that the patient did not have OTC deficiency. Thus the low plasma citrulline level did not validate our initial biochemical suspicion of OTC deficiency, and this highlights the importance of considering all available clinical, biochemical and molecular evidence in determining disease status.

Lesch-Nyhan disease in a 20-year- old man incorrectly described as developing 'cerebral palsy' after general anaesthesia in infancy.

Lesch-Nyhan disease (LND) is a rare X-linked recessive genetic disorder caused by a deficiency of hypoxanthine-guanine phosphoribosyltransferase (HPRT) enzyme. The classic clinical condition is characterized by cognitive impairment, hypotonia at rest, choreoathetosis, hyperuricaemia and the hallmark symptom of severe and involuntary self-mutilation. We describe a man with LND who was initially thought to have suffered from a dyskinetic cerebral palsy after an uncomplicated inguinal herniorrhaphy under general anaesthesia at 5 1/2 months of age. In the absence of overt self-injurious behaviour, the diagnosis was not considered for nearly two decades. The diagnosis of LND was established at 20 years of age through clinical review, biochemical examinations and molecular analysis. HPRT haemolysate activity was 7.6% of the normal control, suggesting that he had a milder variant of the disease. Mutation analysis of the HPRT gene revealed a novel missense mutation, c.449T > G in exon 6 (p.V150G). Cascade testing of family members revealed that the mother was heterozygous for the mutation but two siblings (a brother and a sister) did not carry the sequence mutation. Whether the onset of neurological abnormalities in this particular case can be attributed to the general anaesthesia is discussed.

Influence of low extracellular Ca2+ ions on the cardiac function changes induced by verapamil in the perfused rabbit heart.

We tested the hypothesis that the myocardial effects of verapamil (VER) could be enhanced by decreasing the extracellular Ca2+ concentration ([Ca2+]o) in the isolated rabbit heart at 37 degrees C. After perfusion with standard Krebs - bicarbonate solution containing 1.27 mM Ca2+, for a 30-min period of stabilization and 15 min of control, groups of hearts were perfused for an additional 60 min with solutions containing one of the following: 1.27 mM Ca2+ (control group), 0.23 mM Ca2+ (low [Ca2+]o group), 1.27 mM Ca2+ plus 10(-7) M VER (VER group), or 0.23 mM Ca2+ plus 10(-7) M VER (combination, CBN group). These concentrations of [Ca2+]o and VER produce submaximal responses in our preparation. We found that the heart rate - LV pressure product (RPP) in the CBN group fell rapidly to 0 in the first 2-3 min of perfusion, this response being significantly lower than in the other two groups for the first 15 min. Electromechanical dissociation (EMD) appeared in one of six hearts at 60 min and in four of six hearts at 30 min in the low [Ca2+]o and VER groups, respectively, whereas it occurred in the CBN group in all hearts at 3 min. Depolarization rate (DR) fell by 10% in the low [Ca2+]o and VER groups versus a reduction of 45% in the CBN group (P less than 0.05) during the last 45 min of perfusion. The PR interval increased by 300% in the CBN group, a much greater and significant change (P less than 0.05) than in the hearts exposed to VER or low [Ca2+]o.(ABSTRACT TRUNCATED AT 250 WORDS)

Low extracellular Ca2+ and enzyme release in the perfused rabbit heart.

Previous studies have shown that the well-oxygenated perfused rabbit heart releases creatine kinase when treated with the calcium antagonist drug verapamil (VER) in a dose-related manner. It is possible that this effect is related to Ca2+ ion deprivation of the sarcolemma. This possibility was explored by perfusing hearts with low Ca2+ (0.5, 0.23, 0.15, and 0 mM) versus a control group (1.27 mM Ca2+) for 60 min. Low Ca2+ perfusion was associated with reduction in the heart rate--left ventricular systolic pressure product and O2 consumption, tendency for the coronary sinus flow to increase, electromechanical dissociation, prolongation of atrioventricular conduction and QT interval, and decrease in myocardial glycogen. Lower total adenosine nucleotides were found only in the 0 mM Ca2+ group. As the Ca2+ concentration was reduced, the hearts lost increasing amounts of creatine kinase, aspartate aminotransferase, and lactate dehydrogenase. These results confirm the importance of Ca2+ ions in contractile and electrical cardiac functions and show that decreased availability of this cation leads to increasing enzyme leakage resembling that seen in VER-treated hearts.

Ventricular fibrillation induced prior to cardioplegic arrest in hypertrophied pig hearts.

We hypothesized that by inducing ventricular fibrillation (VF) prior to cardioplegic arrest in nonvented hypertrophied hearts of pigs, the metabolic characteristics of the epicardial and endocardial regions would be compromised compared with animals in which cardioplegic solution was infused while the hearts were in normal sinus rhythm (NSR). These abnormalities would be reflected not only in greater deterioration of myocardial metabolism after reperfusion in the VF group, but they would also be more pronounced in the subendocardial layers of hypertrophied left ventricles. Results obtained in hypothermic hearts (28 degrees C) maintained at 8 degrees to 12 degrees C during cardioplegic arrest demonstrated no major consistent differences in the stores of glycogen, creatine phosphate, adenine nucleotides, and lactate in both groups of hearts, for either layer of the left ventricular myocardium. The only significant difference was slightly lower creatine kinase content in the VF hearts than in the NSR group. It is concluded that induction of VF in hypothermic (28 degrees C), nonvented, hypertrophied hearts prior to infusion of cardioplegic solution does not affect myocardial energy stores compared with hearts in NSR, provided that the period of VF prior to clamping is short (3 minutes) and that the myocardial temperature is lowered to 28 degrees C prior to VF and is maintained at 8 degrees to 12 degrees C during cardioplegic arrest.

Should ventricular fibrillation be induced prior to the infusion of cardioplegic solution?

The present study evaluates the metabolic effects on the left ventricular energy stores of a clinically used cardioplegic solution that was infused into the ascending aorta of pigs while the heart was either fibrillating (induced ventricular fibrillation) or in normal sinus rhythm prior to aortic clamping. Fibrillating hearts had lower stores of glycogen in the epicardium and endocardium compared with hearts in normal sinus rhythm. There was no difference in the stores of creatine phosphate between the hearts for both the epicardium and endocardium, but stores of adenosine triphosphate (ATP) in both layers were lower in fibrillating hearts. These results indicate that for ideal myocardial protection the cardioplegic solution should be infused while the heart is beating under cardiopulmonary bypass, and that ventricular fibrillation induced and maintained prior to cross-clamping may cause myocardial damage.

The hemodynamic and metabolic effects of cardioplegic rearrest in the pig.

The hemodynamic and metabolic effects of two consecutive 1-hour periods of cardioplegic arrest with a 20-minute interval of reperfusion or cardioplegic rearrest were evaluated in pig hearts. This model was designed to recreate in the laboratory a situation occasionally encountered during open-heart operation. Results indicate that at the end of 40 minutes of reperfusion following cardioplegic rearrest and 20 minutes after cardiopulmonary bypass (CPB), the stores of glycogen, adenosine triphosphate and total adenine nucleotides were lower than those found in hearts beating under CPB for an identical period of time. These stores were, however, sufficient to permit hemodynamic recovery, and they compared favorably with those found in hearts subjected to a single hour of cardioplegic arrest and reperfusion. The laboratory data and our previous clinical experience suggest that cardioplegic rearrest is a feasible alternative when surgical difficulties demand a second period of aortic cross-clamping after an initial period of cardioplegic arrest and reperfusion.

Metabolism of the perfused rabbit heart. V. Verapamil-induced release of creatine kinase.

The effects of verapamil (VER), at concentrations of 0 X 10(-9) X 10(-8) X 10(-7), and 5 X 10(-7) M (or 0, 0.5, 5, 50, and 250 ng/mL) were studied in the isolated rabbit heart during 70 min of aerobic perfusion with a standard Krebs-bicarbonate medium at 37 degrees C. The studied variables were left ventricular performance (RPP, heart rate times left ventricular (LV) systolic pressure), coronary sinus flow (CSF), oxygen uptake (MVO2), rate of creatine kinase (CK) release, and energy stores (glycogen, creatine phosphate (CP), ATP, and total adenine nucleotides (TAN) ). The results show that (i) VER depressed RPP in a dose-related manner: (ii) MVO2 declined as VER concentration increased except in the 5 x 10(-7) M group which showed a paradoxical increase in O2 uptake; (iii) CSF was only slightly decreased by VER with the exception of the 5 x 10(-7) M group, which showed an increase in flow; (iv) VER was associated with increments in the rates of CK release in a dose-related fashion (2, 4, 15, and 29 times the rate observed in the untreated group), and (v) VER was associated with slight decrease in glycogen levels, but no changes in CP or adenine nucleotides. It is concluded that, in our preparation, VER caused marked increases in the rate of CK loss in the absence of depletion of total energy stores. The data suggest that the drug affects the permeability characteristics of the sarcolemma, perhaps via localized depletion of calcium stores.

The spectrum of unstable angina: prognostic role of serum creatine kinase determination.

A prospective study of 199 patients with unstable angina pectoris was undertaken to assess whether frequent serial sampling of serum creatine kinase (CK) was useful in predicting prognosis. Nineteen percent of the patients had transient CK elevations suggestive of a small myocardial infarct that was outside the detective ability of conventional electrocardiographic and enzymatic determinations. These patients had a 1 year mortality rate of 16 percent, which was significantly higher than that in the remaining patients (Fisher's exact test p = 0.05). Furthermore, the recurrence rate of myocardial infarction (14 percent) in the patients who had transient CK elevation was significantly greater than that (2 percent) in those who did not have CK elevation (Fisher's exact test p = 0/01). These data suggest that frequent serum CK sampling in the first 48 hours after admission for unstable angina has prognostic value and that persons with CK elevation may warrant a more aggressive approach to investigation and management.

Cardioplegic rearrest: clinical experience with 12 patients.

Myocardial damage due to ischemic arrest occurs during aortic unclamping and early reoxygenation (reperfusion injury). Thus, surgeons may be reluctant to reinfuse cardioplegic agents if a second period of aortic cross-clamping is required at the end of cardiopulmonary bypass. Because of technical difficulties, 12 patients underwent two consecutive periods of cardioplegic arrest with an intervening period of reperfusion of the heart. All survived without complications. Myocardial biopsy specimens from three patients revealed some cellular edema. Serial enzyme levels measured postoperatively compared favourably with those of 12 other patients who had sustained a single period of multidose cardioplegic arrest. Postoperative hemodynamic measurements were similar to preoperative values. Although cardioplegic rearrest may appear safe in the human heart, further studies assessing hemodynamics, morphology and metabolism are necessary in order to delineate fully the changes that occur with this method of myocardial preservation.

Is cardioplegic rearrest safe?

In cardiac bypass procedures the use of anoxic arrest or ventricular fibrillation is known to cause severe myocardial damage. The authors have investigated the safety of using cardioplegic rearrest when surgical difficulties are encountered at the end of cardiac bypass procedure after cardioplegic arrest and reperfusion of the myocardium. From their clinical experience with 12 patients and laboratory experience with 13 pigs the authors conclude that although cardioplegic rearrest is not ideal it can be used safely in this situation.

Cardioplegic arrest in pigs. Effects of glucose-containing solutions.

A clinically used cardioplegic solution was evaluated in the laboratory in an attempt to elucidate the value of glucose in maintaining the glycogen and energy stores of the myocardium during aortic cross-clamping. In one group of animals the cardioplegic solution contained glucose; in the other group it did not. Energy stores were determined in full-thickness biopsies of left ventricular myocardium taken prior to bypass, at 60 minutes of cardioplegic arrest, and after 20 minutes of reperfusion. At the end of cardioplegic arrest, glycogen levels were slightly higher than control values, with no differences between the groups. Creatine phosphate (CP) and adenosine triphosphate (ATP) fell by 69% to 73% and 43% to 55%, respectively, from the control values, but there were no statistical differences between these groups. At the end of reperfusion, glycogen and CP stores had returned to control but ATP concentration remained below control values in both groups. These results indicate that glucose is of no value either to maintain myocardial glycogen or to influence the changes in CP and ATP during cardioplegic arrest. The dissociation between the complete and partial restoration of CP and ATP stores to control levels during reperfusion suggests either that ATP consumption is greater than the energy transfer between CP and ADP:ATP systems or that the energy transfer is defective under these experimental conditions.

Metabolism of the perfused rabbit heart. IV. Effects of beta-adrenergic blockade on enzyme release and later energy stores during postanoxic reoxygenation.

The effects of 80 microM dl-propranolol on left ventricular (LV) performance, energy stores, and creatine kinase (CK) release were studied in a modified Langendorff rabbit heart preparation during 75 min of aerobic perfusion and postanoxic reoxygenation. The data showed that this concentration of propranolol, which blocked the effects of beta-adrenergic stimulation without affecting LV performance, coronary sinus flow (CSF), or oxygen consumption (MV O2), was associated with greater stores of glycogen and adenine nucleotides at the end of aerobic perfusion. Similar effects were observed during postanoxic reoxygenation, when recoveries of left ventricular systolic pressure, heart rate, heart rate--left ventricular systolic pressure product, CSF, and MV O2 remained unchanged during propranolol administration, but myocardial concentrations of glycogen, creatine phosphate, and ATP were greater and the ATP:AMP ratio and the energy charge were higher than in untreated hearts. In addition, the rate of CK loss was lower in the blocked postanoxic hearts than in the unblocked group. These results indicate that propranolol had a beneficial effect on cardiac metabolism during postanoxic recovery tending to normalize energy stores and to reduce enzyme loss during reoxygenation or perfused rabbit hearts without affecting mechanical performance, coronary flow, or O2 metabolism.