How strict is galactose restriction in adults with galactosaemia? International practice

Dietary management of 418 adult patients with galactosaemia (from 39 centres/12 countries) was compared. All centres advised lactose restriction, 6 restricted galactose from galactosides ± fruits and vegetables and 12 offal. 38% (n=15) relaxed diet by: 1) allowing traces of lactose in manufactured foods (n=13) or 2) giving fruits, vegetables and galactosides (n=2). Only 15% (n=6) calculated dietary galactose. 32% of patients were lost to dietetic follow-up. In adult galactosaemia, there is limited diet relaxation.

Blood lactate clearance after maximal exercise depends on active recovery intensity

AIM

High-intensity exercise is time-limited by onset of fatigue, marked by accumulation of blood lactate. This is accentuated at maximal, all-out exercise that rapidly accumulates high blood lactate. The optimal active recovery intensity for clearing lactate after such maximal, all-out exercise remains unknown. Thus, we studied the intensity-dependence of lactate clearance during active recovery after maximal exercise.

METHODS

We constructed a standardized maximal, all-out treadmill exercise protocol that predictably lead to voluntary exhaustion and blood lactate concentration>10 mM. Next, subjects ran series of all-out bouts that increased blood lactate concentration to 11.5±0.2 mM, followed by recovery exercises ranging 0% (passive)-100% of the lactate threshold.

RESULTS

Repeated measurements showed faster lactate clearance during active versus passive recovery (P<0.01), and that active recovery at 60-100% of lactate threshold was more efficient for lactate clearance than lower intensity recovery (P<0.05). Active recovery at 80% of lactate threshold had the highest rate of and shortest time constant for lactate clearance (P<0.05), whereas the response during the other intensities was graded (100%=60%>40%>passive recovery, P<0.05).

CONCLUSION

Active recovery after maximal all-out exercise clears accumulated blood lactate faster than passive recovery in an intensity-dependent manner, with maximum clearance occurring at active recovery of 80% of lactate threshold.

Dietary management of urea cycle disorders: European practice

BACKGROUND

There is no published data comparing dietary management of urea cycle disorders (UCD) in different countries.

METHODS

Cross-sectional data from 41 European Inherited Metabolic Disorder (IMD) centres (17 UK, 6 France, 5 Germany, 4 Belgium, 4 Portugal, 2 Netherlands, 1 Denmark, 1 Italy, 1 Sweden) was collected by questionnaire describing management of patients with UCD on prescribed protein restricted diets.

RESULTS

Data for 464 patients: N-acetylglutamate synthase (NAGS) deficiency, n=10; carbamoyl phosphate synthetase (CPS1) deficiency, n=29; ornithine transcarbamoylase (OTC) deficiency, n=214; citrullinaemia, n=108; argininosuccinic aciduria (ASA), n=80; arginase deficiency, n=23 was reported. The majority of patients (70%; n=327) were aged 0-16y and 30% (n=137) >16y. Prescribed median protein intake/kg body weight decreased with age with little variation between disorders. The UK tended to give more total protein than other European countries particularly in infancy. Supplements of essential amino acids (EAA) were prescribed for 38% [n=174] of the patients overall, but were given more commonly in arginase deficiency (74%), CPS (48%) and citrullinaemia (46%). Patients in Germany (64%), Portugal (67%) and Sweden (100%) were the most frequent users of EAA. Only 18% [n=84] of patients were prescribed tube feeds, most commonly for CPS (41%); and 21% [n=97] were prescribed oral energy supplements.

CONCLUSIONS

Dietary treatment for UCD varies significantly between different conditions, and between and within European IMD centres. Further studies examining the outcome of treatment compared with the type of dietary therapy and nutritional support received are required.

Dietary practices in pyridoxine non-responsive homocystinuria: a European survey

BACKGROUND

Within Europe, the management of pyridoxine (B6) non-responsive homocystinuria (HCU) may vary but there is limited knowledge about treatment practice.

AIM

A comparison of dietetic management practices of patients with B6 non-responsive HCU in European centres.

METHODS

A cross-sectional audit by questionnaire was completed by 29 inherited metabolic disorder (IMD) centres: (14 UK, 5 Germany, 3 Netherlands, 2 Switzerland, 2 Portugal, 1 France, 1 Norway, 1 Belgium).

RESULTS

181 patients (73% >16 years of age) with HCU were identified. The majority (66%; n=119) were on dietary treatment (1-10 years, 90%; 11-16 years, 82%; and >16 years, 58%) with or without betaine and 34% (n=62) were on betaine alone. The median natural protein intake (g/day) on diet only was, by age: 1-10 years, 12 g; 11-16 years, 11 g; and >16 years, 45 g. With diet and betaine, median natural protein intake (g/day) by age was: 1-10 years, 13 g; 11-16 years, 20 g; and >16 years, 38 g. Fifty-two percent (n=15) of centres allocated natural protein by calculating methionine rather than a protein exchange system. A methionine-free l-amino acid supplement was prescribed for 86% of diet treated patients. Fifty-two percent of centres recommended cystine supplements for low plasma concentrations. Target treatment concentrations for homocystine/homocysteine (free/total) and frequency of biochemical monitoring varied.

CONCLUSION

In B6 non-responsive HCU the prescription of dietary restriction by IMD centres declined with age, potentially associated with poor adherence in older patients. Inconsistencies in biochemical monitoring and treatment indicate the need for international consensus guidelines.

Culturing rat hippocampal neurons

Cultured neurons are widely used to investigate the mechanisms of neurotoxicity. Embryonic rat hippocampal neurons may be grown as described under a wide variety of conditions to suit differing experimental procedures, including electrophysiology, morphological analysis of neurite development, and various biochemical and molecular analyses.

RhoD participates in the regulation of cell-cycle progression and centrosome duplication

We have previously identified a Rho protein, RhoD, which localizes to the plasma membrane and the early endocytic compartment. Here, we show that a GTPase-deficient mutant of RhoD, RhoDG26V, causes hyperplasia and perturbed differentiation of the epidermis, when targeted to the skin of transgenic mice. In vitro, gain-of-function and loss-of-function approaches revealed that RhoD is involved in the regulation of G1/S-phase progression and causes overduplication of centrosomes. Centriole overduplication assays in aphidicolin-arrested p53-deficient U2OS cells, in which the cell and the centrosome cycles are uncoupled, revealed that the effects of RhoD and its mutants on centrosome duplication and cell cycle are independent. Enhancement of G1/S-phase progression was mediated via Diaph1, a novel effector of RhoD, which we have identified using a two-hybrid screen. These results indicate that RhoD participates in the regulation of cell-cycle progression and centrosome duplication.

Dietary management of urea cycle disorders: UK practice

BACKGROUND

There is no published data describing UK dietary management of urea cycle disorders (UCD). The present study describes dietary practices in UK inherited metabolic disorder (IMD) centres.

METHODS

Cross-sectional data from 16 IMD centres were collected by a questionnaire describing the management of UCD patients on prescribed protein-restricted diets.

RESULTS

One hundred and seventy-five patients [N-acetylglutamate synthase deficiency, n = 3; carbamoyl phosphate synthase deficiency (CPS), n = 8; ornithine transcarbamoylase deficiency (OTC), n = 75; citrullinaemia, n = 41; argininosuccinic aciduria (ASA), n = 36; arginase deficiency, n = 12] were reported; 70% (n = 123) aged 0-16 years; 30% (n = 52) >16 years. Prescribed median protein intake decreased with age (0-6 months: 2 g kg(-1) day(-1); 7-12 months: 1.6 g kg(-1) day(-1); 1-10 years: 1.3 g kg(-1) day(-1); 11-16 years: 0.9 g kg(-1) day(-1) and >16 years: 0.8 g kg(-1) day(-1)) with little variation between disorders. Adult protein prescription ranged 0.4-1.2 g kg(-1) day(-1) (40-60 g day(-1)). In the previous 2 years, 30% (n = 53) were given essential amino acid supplements (EAAs) (CPS, n = 2; OTC, n = 20; citrullinaemia, n = 15; ASA, n = 7; arginase deficiency, n = 9). EAAs were prescribed for low plasma quantitative essential amino acids (n = 13 centres); inadequate natural protein intake (n = 11) and poor metabolic control (n = 9). From diagnosis, one centre prescribed EAAs for all patients and one centre for severe defects only. Only 3% (n = 6) were given branch chain amino acid supplements. Enteral feeding tubes were used by 25% (n = 44) for feeds and 3% (n = 6) for medications. Oral energy supplements were prescribed in 17% (n = 30) of cases.

CONCLUSIONS

In the UK, protein restriction based on World Health Organization 'safe intakes of protein', is the principle dietary treatment for UCD. EAA supplements are prescribed mainly on clinical need. Multicentre collaborative research is required to define optimal dietary treatments.