Total body nitrogen in prepubertal children

Nutritional care in children with cystic fibrosis: are our patients becoming better?

Over the last 30 years, major advances have occurred in our understanding of the disorder cystic fibrosis (CF) with the discoveries of the underlying chloride transport defect and the 'CF gene', the CF transmembrane conductance regulator gene. Equally important from a clinical and patient perspective are the improvements in median survival from less than 10 to 20 years prior to 1980, approaching 30 years during the 1980s and over 45 years more recently. Improved antibiotic regimens and lung clearance therapy contributed to the enhanced survival, but a key factor accredited as adding a further 10 years to the median survival was improving and then maintaining normal growth and nutrition. In the main, the latter were achieved by adherence to a 'high-fat high-energy' diet rather than the advocated virtually universal policy of the 'low fat', which was associated with wasting and linear growth failure. The high-fat diet in conjunction with better control of malabsorption due to microspheric pancreatic enzyme replacement therapy, attention to adequate fat-soluble vitamin supplementation and newborn screening has ensured that at least 80-90% of children with CF will achieve better health and survival through their adult years.

The effect of gastrostomy tube feeding on body protein and bone mineralization in children with quadriplegic cerebral palsy

AIM

The aim of this study was to investigate the effect of gastrostomy tube feeding on body protein and bone mineralization in malnourished children with cerebral palsy (CP).

METHOD

Children aged between 4 and 18 years with spastic quadriplegic CP (Gross Motor Function Classification System level V) were recruited from the Children's Hospital at Westmead to participate in this prospective cohort study. The children had measurements of anthropometry (weight, height, and skinfold), bone mineral content (BMC) by dual-energy X-ray absorptiometry, and total body protein (TBP) by neutron activation analysis before and after gastrostomy tube feeding. Comparison data were collected prospectively from age-matched healthy children and extracted from databases for this study.

RESULTS

A total of 21 children (nine females, 12 males) participated in the study (median age 8 y 5 mo; interquartile range [IQR] 6 y 9 mo-11 y 10 mo). The median length of time of gastrostomy feeding was 19.4 months (IQR 7.7-29.9 mo). Significant (p<0.05) improvements were found in the median values for weight (15.4-23.3 kg), weight standard deviation scores (SDS; -4.8 to -3.0), height (105.4-118.3 cm), per cent body fat (10.7-16.3), TBP (2.4-3.4 kg), TBP per cent predicted for height (83.4-99.0), and BMC (469-626 g). No significant increases were found in height SDS, TBP per cent predicted for age, or BMC SDS for age or height.

INTERPRETATION

Malnourished children with quadriplegic CP showed significant increases in body fat and protein with gastrostomy tube feeding. No significant change in bone mineralization predicted for age or height was observed.

The nutritional relationship linking sulfur to nitrogen in living organisms

Nitrogen (N) and sulfur (S) coexist in the biosphere as free elements or in the form of simple inorganic NO3- and SO4(2-) oxyanions, which must be reduced before undergoing anabolic processes leading to the production of methionine (Met) and other S-containing molecules. Both N and S pathways are tightly regulated in plant tissues so as to maintain S:N ratios ranging from 1:20 to 1:35. As a result, plant products do not adequately fulfill human tissue requirements, whose mean S:N ratios amount to 1:14.5. The evolutionary patterns of total body N (TBN) and of total body S (TBS) offer from birth to death sex- and age-related specificities well identified by the serial measurement of plasma transthyretin (TTR). Met is regarded as the most limiting of all indispensable amino acids (IAAs) because of its participation in a myriad of molecular, structural, and metabolic activities of survival importance. Met homeostasis is regulated by subtle competitive interactions between transsulfuration and remethylation pathways of homocysteine (Hcy) and by the actual level of TBN reserves working as a direct sensor of cystathionine-beta-synthase activity. Under steady-state conditions, the dietary intake of SO4(2-) is essentially equal to total sulfaturia. The recommended dietary allowances for both S-containing AAs allotted to replace the minimal obligatory losses resulting from endogenous catabolism is largely covered by Western customary diets. By contrast, strict vegans and low-income populations living in plant-eating countries incur the risk of chronic N and Met dietary deficiencies causing undesirable hyperhomocysteinemia best explained by the downsizing of their TBN resources and documented by declining TTR plasma values.

Reduced body protein in children with spastic quadriplegic cerebral palsy

BACKGROUND

No studies have directly measured body protein or validated skinfold-thickness anthropometry and dual-energy X-ray absorptiometry (DXA) to assess body protein in children with spastic quadriplegic cerebral palsy (SQCP).

OBJECTIVE

We aimed to measure and evaluate body protein and to determine whether skinfold-thickness anthropometry and DXA can predict body protein in children with SQCP.

DESIGN

This was a cross-sectional study of 59 children (22 girls, 37 boys) aged 3.9-19.5 y with SQCP. The children underwent measurements of anthropometric indexes, lean tissue mass by DXA (LTM(DXA)), and total body protein by neutron activation analysis (TBP(NAA)). In addition, TBP was estimated from both skinfold-thickness anthropometry (TBP(SKIN)) and DXA (TBP(DXA)). The agreement of TBP(SKIN) and TBP(DXA) was tested against TBP(NAA) by using Bland and Altman plot analysis.

RESULTS

Height and weight SD scores (x +/- SD: -3.1 +/- 1.6 and -4.8 +/- 5.3, respectively) were significantly lower than reference data in the children with SQCP (P < 0.001). TBP(NAA) for age and height was low in the children with SQCP (P < 0.001): 56.1 +/- 17.3% and 81.5 +/- 15.7%, respectively, of the values predicted from control data. TBP(SKIN) and TBP(DXA) were both highly correlated with TBP(NAA): r = 0.90, P < 0.001, and r = 0.91, P < 0.001, respectively. Despite these significant correlations, agreement analyses showed wide variation of up to 33.3% of the mean for both methods.

CONCLUSIONS

Body protein in children with SQCP is significantly reduced for age and height. Skinfold anthropometry and DXA show wide variation in estimation of body protein compared with NAA in this group of children.