Sulphur Amino Acids: How Important is it to Set Reference Ranges for Each Population?

INTRODUCTION

Metabolism of sulfur amino acids requires an optimal interplay between nutritional demand, enzymes, transporters, and adequate dietary intake of B vitamins. Insufficient intake and excess are detrimental, and concentrations depend on health status. However, plasma aminothiol concentrations, previously reported in healthy subjects using highly sensitive methods, vary considerably, and age- and gender differences were observed. Therefore, defining age- and gender-specific ranges for each population is crucial to evaluate the meaning of plasma thiol redox state in health and disease.

METHODS

A healthy Portuguese pediatric population (n=90), aged 9- (n=38) and 17-year-old (n=52), was evaluated. Plasma aminothiols, total homocysteine (tHcy), cysteine (tCys), glutathione (tGSH) and γ-glutamylcysteine (tγ-Glu-Cys), were analysed as SBD-F derivatives by HPLC with fluorescence detection.

RESULTS/CASE REPORT

Mean plasma concentrations (SD) for the 9- and the 17-year-old groups, were as following: tHcy = 4.58 (0.98); 8.13 (3.27) µM, p <0.001; tCys = 207.34 (32.07); 198.59 (21.24) µM, p = 0.274; tGSH = 4.54 (1.08); 5.20 (1.84) µM, p = 0.123 and tγ-Glu-Cys = 1.47 (0.30); 1.06 (0.28) µM, p < 0.001, respectively. No statistically significant differences were found between males and females in the 9-year-old group. However, in the 17-year-old group, significant differences between genders were observed for tHcys (p < 0.001) and tγ-Glu-Cys (p = 0.039), with males presenting the highest concentrations. When correlating the four thiols' plasma concentrations, only the precursors of glutathione, tγ-Glu-Cys and tCys, were positively correlated (r = 0.450, p < 0.001).

CONCLUSION

Our results showed significant differences in tHcy and tγ-Glu-Cys levels across both age groups, which increased and decreased with age, respectively. It is interesting to highlight that in the 17-year-old group, tHcy and tγ-Glu-Cys levels were higher in males than in females. These observations showed that age and gender influence plasma levels of thiols, which may impact cellular oxidative status. In conclusion, setting age and gender distinct ranges for each specific population is of utmost importance for understanding disease mechanisms and the effectiveness of therapeutic interventions.

Vimentin Diversity in Health and Disease

Vimentin is a protein that has been linked to a large variety of pathophysiological conditions, including cataracts, Crohn's disease, rheumatoid arthritis, HIV and cancer. Vimentin has also been shown to regulate a wide spectrum of basic cellular functions. In cells, vimentin assembles into a network of filaments that spans the cytoplasm. It can also be found in smaller, non-filamentous forms that can localise both within cells and within the extracellular microenvironment. The vimentin structure can be altered by subunit exchange, cleavage into different sizes, re-annealing, post-translational modifications and interacting proteins. Together with the observation that different domains of vimentin might have evolved under different selection pressures that defined distinct biological functions for different parts of the protein, the many diverse variants of vimentin might be the cause of its functional diversity. A number of review articles have focussed on the biology and medical aspects of intermediate filament proteins without particular commitment to vimentin, and other reviews have focussed on intermediate filaments in an in vitro context. In contrast, the present review focusses almost exclusively on vimentin, and covers both ex vivo and in vivo data from tissue culture and from living organisms, including a summary of the many phenotypes of vimentin knockout animals. Our aim is to provide a comprehensive overview of the current understanding of the many diverse aspects of vimentin, from biochemical, mechanical, cellular, systems biology and medical perspectives.

Guanidinoacetate methyltransferase (GAMT) deficiency: outcomes in 48 individuals and recommendations for diagnosis, treatment and monitoring

We collected data on 48 patients from 38 families with guanidinoacetate methyltransferase (GAMT) deficiency. Global developmental delay/intellectual disability (DD/ID) with speech/language delay and behavioral problems as the most affected domains was present in 44 participants, with additional epilepsy present in 35 and movement disorder in 13. Treatment regimens included various combinations/dosages of creatine-monohydrate, l-ornithine, sodium benzoate and protein/arginine restricted diets. The median age at treatment initiation was 25.5 and 39 months in patients with mild and moderate DD/ID, respectively, and 11 years in patients with severe DD/ID. Increase of cerebral creatine and decrease of plasma/CSF guanidinoacetate levels were achieved by supplementation with creatine-monohydrate combined with high dosages of l-ornithine and/or an arginine-restricted diet (250 mg/kg/d l-arginine). Therapy was associated with improvement or stabilization of symptoms in all of the symptomatic cases. The 4 patients treated younger than 9 months had normal or almost normal developmental outcomes. One with inconsistent compliance had a borderline IQ at age 8.6 years. An observational GAMT database will be essential to identify the best treatment to reduce plasma guanidinoacetate levels and improve long-term outcomes.