Investigation of L - Carnitine Concentrations in Treated Patients with Maple Syrup Urine Disease

Maple syrup urine disease (MSUD), also known as branched-chain α ketoaciduria, is a metabolic disorder caused by an inborn deficiency in the activity of the branched-chain α-ketoacid dehydrogenase complex. Severe neurological damage occurs in most patients with MSUD although the exact mechanism of neurotoxicity still remains unknown. Studies have suggested that neuropathology in patients with MSUD may be related to oxidative stress. L - carnitine mediates the transport of fatty acids into the mitochondria that are required for β-oxidation and ATP production. Along with the important roles it plays in lipid metabolism, L-carnitine also protects tissues from oxidative damage through its antioxidant properties. The study included a total of 15 patients with MSUD who attended regular follow-up visits, and 15 age-matched healthy control subjects, and aimed to investigate L - carnitine levels in treated patients with MSUD and healthy control subjects. L - carnitine levels were found to be significantly lower in the patient group than in the healthy controls. No significant correlation was identified between the plasma branched-chain amino acids leucine, isoleucine, valine, and L - carnitine levels. Patients with MSUD can be treated with adjuvant therapy with L - carnitine supplementation.

Studying the effect of large neutral amino acid supplements on oxidative stress in phenylketonuric patients

Background Oxidative stress may be one of the causes responsible for mental retardation in phenylketonuria (PKU) patients. Phenylalanine (Phe) reduces antioxidant defense and promotes oxidative stress by causing increase in reactive oxygen-nitrogen species. Our study aimed to investigate the effect of different treatments (amino acid mixture/large neutral amino acid [LNAA] supplements) on oxidative stress which are applied to late-diagnosed patients. To the best of our knowledge, this is the first study to investigate the effect of LNAA supplements on oxidative stress. Methods Twenty late-diagnosed classic PKU patients were included in this study. Patients were classified into two groups: patients under Phe-restricted diet and using Phe-free amino acid mixtures (Group I) (mean age: 13.8 ± 2.8), and patients taking LNAA supplements (Group II) (mean age: 14.8 ± 3.8). Healthy controls (mean age: 13.6 ± 4.8) with ages consistent with the ages of the patients in the experimental groups were included. Results Glutathione peroxidase is lower in patients of taking LNAA supplements than the control group (p = 0.022). Coenzyme Q10 is lower in patients of using Phe-free amino acid mixtures than the control group and it is significantly higher in Group II than Group I (p = 0.0001, p = 0.028, respectively). No significant differences were detected in total antioxidant status, total oxidant status, oxidative stress index, paraoxonase 1 and L-carnitine levels. Conclusions Different treatments affect oxidative stress parameters in PKU patients. In this study, although patients were followed up with classic PKU, patient-specific adjuvant antioxidant therapies should be implemented in response to oxidative stress.

Weaning practices in phenylketonuria vary between health professionals in Europe

Background

In phenylketonuria (PKU), weaning is considered more challenging when compared to feeding healthy infants. The primary aim of weaning is to gradually replace natural protein from breast milk or standard infant formula with solids containing equivalent phenylalanine (Phe). In addition, a Phe-free second stage L-amino acid supplement is usually recommended from around 6 months to replace Phe-free infant formula. Our aim was to assess different weaning approaches used by health professionals across Europe.

Methods

A cross sectional questionnaire (survey monkey®) composed of 31 multiple and single choice questions was sent to European colleagues caring for inherited metabolic disorders (IMD). Centres were grouped into geographical regions for analysis.

Results

Weaning started at 17–26 weeks in 85% (n = 81/95) of centres, >26 weeks in 12% (n = 11/95) and < 17 weeks in 3% (n = 3/95). Infant's showing an interest in solid foods, and their age, were important determinant factors influencing weaning commencement. 51% (n = 48/95) of centres introduced Phe containing foods at 17–26 weeks and 48% (n = 46/95) at >26 weeks. First solids were mainly low Phe vegetables (59%, n = 56/95) and fruit (34%, n = 32/95).

A Phe exchange system to allocate dietary Phe was used by 52% (n = 49/95) of centres predominantly from Northern and Southern Europe and 48% (n = 46/95) calculated most Phe containing food sources (all centres in Eastern Europe and the majority from Germany and Austria). Some centres used a combination of both methods.

A second stage Phe-free L-amino acid supplement containing a higher protein equivalent was introduced by 41% (n = 39/95) of centres at infant age 26–36 weeks (mainly from Germany, Austria, Northern and Eastern Europe) and 37% (n = 35/95) at infant age > 1y mainly from Southern Europe. 53% (n = 50/95) of centres recommended a second stage Phe-free L-amino acid supplement in a spoonable or semi-solid form.

Conclusions

Weaning strategies vary throughout European PKU centres. There is evidence to suggest that different infant weaning strategies may influence longer term adherence to the PKU diet or acceptance of Phe-free L-amino acid supplements; rendering prospective long-term studies important. It is essential to identify an effective weaning strategy that reduces caregiver burden but is associated with acceptable dietary adherence and optimal infant feeding development.

Early feeding practices in infants with phenylketonuria across Europe

Background

In infants with phenylketonuria (PKU), dietary management is based on lowering and titrating phenylalanine (Phe) intake from breast milk or standard infant formula in combination with a Phe-free infant formula in order to maintain blood Phe levels within target range. Professionals use different methods to feed infants with PKU and our survey aimed to document practices across Europe.

Methods

We sent a cross sectional, survey monkey® questionnaire to European health professionals working in IMD. It contained 31 open and multiple-choice questions. The results were analysed according to different geographical regions.

Results

Ninety-five centres from 21 countries responded. Over 60% of centres commenced diet in infants by age 10 days, with 58% of centres implementing newborn screening by day 3 post birth. At diagnosis, infant hospital admission occurred in 61% of metabolic centres, mainly in Eastern, Western and Southern Europe. Breastfeeding fell sharply following diagnosis with only 30% of women still breast feeding at 6 months.

53% of centres gave pre-measured Phe-free infant formula before each breast feed and 23% alternated breast feeds with Phe-free infant formula. With standard infant formula feeds, measured amounts were followed by Phe-free infant formula to satiety in 37% of centres (n = 35/95), whereas 44% (n = 42/95) advised mixing both formulas together. Weaning commenced between 17 and 26 weeks in 85% centres, ≥26 weeks in 12% and < 17 weeks in 3%.

Discussion

This is the largest European survey completed on PKU infant feeding practices. It is evident that practices varied widely across Europe, and the practicalities of infant feeding in PKU received little focus in the PKU European Guidelines (2017). There are few reports comparing different feeding techniques with blood Phe control, Phe fluctuations and growth. Controlled prospective studies are necessary to assess how different infant feeding practices may influence longer term feeding development.

Relationship of fibroblast growth factor 21, sirtuin 1, visfatin, and regulators in children with short stature

Fibroblast growth factor 21 (FGF21) is mainly secreted by the liver. It is a factor that is not fully understood in relation to growth. Sirtuin 1 (SIRT1) is a deacetylase protein. It is thought that may have an effect on the release and function of GH and IGF-1. Visfatin is synthesized from adipose tissue as primary. It may be prognostic marker associated with growth factors. As a result of our work, FGF21 is not associated with short stature but levels of SIRT1 and visfatin are associated with short stature. The decrease in visfatin value in the short-stature group is thought to be due to an insufficient amount of adipose tissue, which is important for growth and development. SIRT1 might decrease GH effect by increasing STAT5 deacetylation in the liver and we think that the result of this reduction of SIRT1 would negatively impact IGF-1 and IGFBP-3 production.

Effect of Blood Phenylalanine Levels on Oxidative Stress in Classical Phenylketonuric Patients

Mental retardation, which occurs in phenylketonuric patients, is associated with increased levels of phenylalanine, increased oxidative stress, and an imbalance of amino acids in the brain. Recent studies have shown that oxidative stress plays a role in the pathogenesis of phenylketonuria. In this work, we aimed to compare the influence of blood phenylalanine levels on oxidative stress parameters in phenylketonuric patients who divided patients into groups according to blood Phe levels during follow-up visits and compared these groups with healthy controls. Results showed significant differences in glutathione peroxidase (GSHPx), coenzyme Q10 (Q10), Q10/cholesterol, and L-carnitine levels in phenylketonuria patients and the control group. GSHPx, Q10, and Q10/cholesterol levels were significantly lower in poor adherence patients than in the control groups. L-carnitine levels were significantly increased in good adherence patients than poor adherence patients and decreased in poor adherence patients than healthy controls. No correlations were observed between phenylalanine and L-carnitine concentrations in poor adherence group. No significant differences were observed in paraoxonase 1 (PON1), total antioxidant status (TAS), total oxidant status (TOS) and oxidative stress index (OSI) levels. As a result, in this work, poor adherence patients are prone to oxidative stress. Although the patients may have the same diagnosis, patients have different clinical characteristics and different prognosis. Antioxidants can be used as an adjuvant therapy in order to avoid neurological damage in these patients.