Milk protein oxidation in healthy subjects:A preliminary study

The role of protein oxidation in the regulation of whole body protein metabolism is unknown. Previously, it was observed that vigorous exercise led to increased protein oxidation. To further characterise 13C-milk protein oxidation in healthy subjects, the oxidation of ingested 13C-protein after an overnight fast was measured using a non-invasive 13C-protein breath test. This approach enables the analysis of 13C-protein oxidation kinetics and the effect of interfering factors. It was found that the estimated maximal 13C-milk protein oxidation was 0.07 g min−1, corresponding to a theoretical maximal oxidation capacity of ≈1.4 g kg body weight−1 d−1. No indications were found for preferential oxidation of non-essential amino acids. Combined ingestion of 30 g 13C-whey protein with 30 g glucose resulted in a 19% decrease of 13C-whey protein oxidation. It was concluded that exogenous 13C-whey protein oxidation can be affected by other co-ingested nutrients like glucose

Refined crystal structure of lipoamide dehydrogenase from Azotobacter vinelandii at 2.2 Å resolution: A comparison with the structure of glutathione reductase

The structure of lipoamide dehydrogenase from Azotobacter vinelandii has been refined by the molecular dynamics technique to an R-factor of 19.8% at 2.2 Å resolution. In the final model, the root-mean-square deviation from ideality is 0.02 Å for bond lengths and 3.2 ° for bond angles. The asymmetric unit comprises two subunits, each consisting of 466 amino acid residues and the prosthetic group FAD, plus 512 solvent molecules. The last ten amino acid residues of both chains are not visible in the electron density distribution and they are probably disordered. The operation required to superimpose the two chains forming the dimer is a rotation of exactly 180 ° with no translation component. The final model shows the two independently refined subunits to be very similar, except for six loops located at the surface of the molecul

Refined crystal structure of lipoamide dehydrogenase from Azotobacter vinelandii at 2.2 A resolution. A comparison with the structure of glutathione reductase

The structure of lipoamide dehydrogenase from Azotobacter vinelandii has been refined by the molecular dynamics technique to an R-factor of 19.8% at 2.2 A resolution. In the final model, the root-mean-square deviation from ideality is 0.02 A for bond lengths and 3.2 degrees for bond angles. The asymmetric unit comprises two subunits, each consisting of 466 amino acid residues and the prosthetic group FAD, plus 512 solvent molecules. The last ten amino acid residues of both chains are not visible in the electron density distribution and they are probably disordered. The operation required to superimpose the two chains forming the dimer is a rotation of exactly 180 degrees with no translation component. The final model shows the two independently refined subunits to be very similar, except for six loops located at the surface of the molecule. The structure of each subunit of the enzyme consists of four domains with the catalytic centre located at the subunit interface. The reactive disulphide bridge, 48-53, is oxidized with S gamma of Cys53 located 3.5 A away from carbon C-4a of the isoalloxazine ring. The side-chain of His450' points its N epsilon 2 towards S gamma of Cys48 and is hydrogen bonded to the carboxylate of Glu455'. The FAD is bound in an extended conformation and the isoalloxazine ring is not completely planar with an angle between the pteridine and the benzene ring of 7.3 degrees in the first subunit and of 12.1 degrees in the second one. The overall folding of lipoamide dehydrogenase is very similar to that of glutathione reductase. However, a comparison of the two enzymes, which have only 26% sequence identity, reveals significant conformational differences. These concern the tertiary as well as the quaternary structure of the two molecules. In each subunit of lipoamide dehydrogenase the NAD-binding domain and the interface domain appear to be differently oriented with respect to the FAD-binding domain by 7.1 degrees and 7.8 degrees, respectively. The interface domain contains, in addition, major changes in tertiary structure. Furthermore, the two subunits forming the dimer appear to be shifted with respect to each other by more than 4 A, when the lipoamide dehydrogenase dimer is compared with that of glutathione reductase. In spite of all these changes at the tertiary and quaternary level the active sites of the enzymes, which occur at the dimer interface, appear to be remarkably similar

Milk protein oxidation in healthy subjects: A preliminary study

The role of protein oxidation in the regulation of whole body protein metabolism is unknown. Previously, it was observed that vigorous exercise led to increased protein oxidation. To further characterise C-13-milk protein oxidation in healthy subjects, the oxidation of ingested C-13-protein after an overnight fast was measured using a non-invasive C-13-protein breath test. This approach enables the analysis of C-13-protein oxidation kinetics and the effect of interfering factors. It was found that the estimated maximal C-13-milk protein oxidation was 0.07 g min(-1), corresponding to a theoretical maximal oxidation capacity of approximate to 1.4 g kg body weight(-1) d(-1). No indications were found for preferential oxidation of non-essential amino acids. Combined ingestion of 30 g C-13-whey protein with 30 g glucose resulted in a 19% decrease of C-13-whey protein oxidation. It was concluded that exogenous C-13-whey protein oxidation can be affected by other co-ingested nutrients like glucose. (C) 2020 The Authors. Published by Elsevier Ltd

Parenting preschoolers with autism: Socioeconomic influences on wellbeing and sense of competence.

BACKGROUND: Previous research suggests that parents raising a child with autism experience higher levels of psychological distress than parents of typically developing children and parents of children with other developmental disorders. Little is known, however, about the intersection between the effects of socioeconomic status (SES) on the wellbeing and sense of parental competency of parents of pre-schoolers with autism and how it relates to child symptom severity. AIM: To examine the relationship between their child's symptom severity, SES, as measured by neighbourhood advantage and occupational status, on the psychological wellbeing and perceived parenting competence among parents of preschoolers with autism. METHODS: Parents of 117 preschool-aged children with a diagnosis of autism spectrum disorder (ASD), 107 mothers and 54 fathers, completed questionnaires about their child's symptoms of ASD and functioning, their own perceptions of their wellbeing and parental competence on entry to an early intervention program in Sydney, Australia. Parents also provided demographic information pertaining to their occupation, level of education attained and address (postcode). All children were also assessed for their severity of symptoms using the Autism Diagnostic Observation Schedule. The Australian Socioeconomic Index of occupational status as a measure of familial SES and the Index of Relative Socio-economic Advantage and Disadvantage as a measure of neighbourhood advantage were used to examine the impact of SES on parental sense of competence and wellbeing. RESULTS: Compared to normative populations, both mothers and fathers in our sample reported significantly higher levels of parenting sense of efficacy but lower levels of interest in the parenting role. Mothers also displayed higher levels of satisfaction. Both mothers and fathers displayed higher levels of depression than normative populations with mothers also reporting greater levels of stress and anxiety. Child symptom severity was associated with maternal parenting competency with these relationships amplified among mothers with higher familial SES and who lived in areas of greater neighbourhood advantage. Increased adaptive functioning was associated with better maternal wellbeing, particularly among mothers who lived in areas of greater neighbourhood advantage. Contrastingly, paternal parenting competence was generally not influenced by child adaptive functioning or symptom severity, although for those in higher familial SES brackets, children's symptom severity and maladaptive symptoms were negatively related to paternal sense of parenting efficacy. There was a trend towards moderate relationships between lower familial SES and greater depression, stress and anxiety among fathers, but no relationship with their child's ASD symptom severity or functioning. CONCLUSION: SES differentially impacts wellbeing and sense of parenting competence and its relationship to the impact of child symptoms for mothers and fathers of preschoolers with autism

Accurate measurement of the essential micronutrients methionine, homocysteine, vitamins B6, B12, B9 and their metabolites in plasma, brain and maternal milk of mice using LC/MS ion trap analysis

Methionine, homocysteine, vitamins B6, B12, B9, and their metabolites are crucial co-factors and substrates for many basic biological pathways including one-carbon metabolism, and they are particularly important for brain function and development and epigenetic mechanisms. These are essential nutrients that cannot be synthesized endogenously and thus need to be taken in via diet. A novel method was developed that enables simultaneous assessment of the exact concentrations of these essential micronutrients in various matrices, including maternal milk, plasma, and brain of neonatal mice. The protocol for analysis of these components in the various matrices consists of a cleanup step (i.e. lipid extraction followed by protein precipitation) combined with a liquid chromatography mass spectrometry (LC/MS) ion trap method with high sensitivity and selectivity (SRM mode). This novel method enables the measurement of these essential nutrients with good recoveries (69-117%), and high intra-day (<10%) and high intra-day precision (defined as <15% for compounds with an isotopologue and <20% for compounds without an isotopologue as internal standard) in plasma, maternal milk, and brain of mice at low and high levels. In addition, lower limits of quantitation (LOQ) were determined for the various matrices in the range for methionine (700-2000nmol/L), homocysteine (280-460-nmol/L), vitamins B6 (5-230nmol/L), B12 (7-11nmol/L), B9 (20-30nmol/L). Degradation of vitamins and oxidation of homocysteine is limited to a minimum, and only small sample volumes (30μL plasma, 20mg brain and maternal milk) are needed for simultaneous measurement. This method can help to understand how these nutrients are transferred from mother to offspring via maternal milk, as well as how these nutrients are absorbed by the offspring and eventually taken up in various tissues amongst the brain in preclinical and clinical research settings. Therefore the method can help to explore critical periods in lactating mothers and developing offspring