Thymulin (Zn-FTS) activity in protein-energy malnutrition: new evidence for interaction between malnutrition and infection on thymic function

Thymus gland size during recovery from complicated severe acute malnutrition: a prospective study of the role of probiotics

Background: Children with severe acute malnutrition (SAM) are prone to infections due to immune dysfunction including severe thymus atrophy which recovers during nutritional rehabilitation. Aim: To investigate predictors of thymus size recovery, including probiotics during nutritional rehabilitation of children admitted with complicated SAM. Methods: In this prospective study nested in a randomized controlled trial, children 6-59 months admitted with SAM received standard care and either probiotics or placebo during hospitalization until 8 weeks post-discharge. Thymus size was measured using ultrasound at admission, discharge, 8 weeks post-discharge and among 27 community controls. Predictors of thymus size recovery were assessed using linear regression. Results: Among 388 children with SAM, mean (SD) thymus size was 1.06 cm2 (0.41), 1.24 cm2 (0.48), 2.85 cm2 (1.07) and 4.2 cm2 (0.93) at admission, discharge, follow-up and in the healthy controls respectively (p < 0.05).Probiotics did not affect thymus recovery. During both inpatient therapeutic care (ITC) and outpatient therapeutic care (OTC), thymus recovery correlated positively with anthropometry but negatively with caregiver-perceived illness severity and Haemoglobin <8 g/dl. Negative predictors of thymus recovery during ITC included grade 3 oedema (β -0.13, 95%CI -0.25; -0.01), dermatosis (β -0.21, 95%CI -0.41; -0.01), C-reactive protein (CRP) >15mg/L (β -0.13, 95%CI -0.25; -0.02) and neutrophils (β -0.01, 95%CI -0.02; -0.002). During OTC, HIV negatively predicted thymus recovery. Conclusion: Children with SAM failed to regain thymus size at 8 weeks post-discharge. Probiotics did not predict thymus recovery during nutritional rehabilitation. More research is needed to find interventions which can accelerate immune recovery. Abbreviations: ART, Antiretroviral therapy; BB-12, Bifidobacterium animalis subsp. Lactis; CRP, C-reactive protein; ITC, inpatient therapeutic care; LGG, Lactobacillus rhamnosus; MNU, Mwanamugimu Nutrition Unit; MUAC, mid-upper arm circumference; OTC, outpatient therapeutic care; PCR, Polymerised chain reaction; RUTF, ready-to-use therapeutic food; SAM, severe acute malnutrition; VAS, visual analogue score; WHO, World Health Organization; WHZ, weight-for-height score.

Plasma zinc concentration responds to short-term zinc supplementation, but not zinc fortification, in young children in Senegal1,2

BACKGROUND

Simple, low-cost methods are needed to evaluate the effect of zinc-fortification programs. Plasma zinc concentration is a useful biomarker of zinc intake from supplementation, but responses to zinc fortification are inconsistent.

OBJECTIVE

The objective was to compare the change in plasma zinc concentrations in young children who received zinc from either a liquid supplement or a zinc-fortified complementary food.

DESIGN

A double-blind intervention trial was conducted in 137 young Senegalese children aged 9-17 mo who were randomly assigned to receive one of the following treatments for 15 d: 1) 30 g dry weight of an iron-fortified cereal porridge and a liquid multivitamin supplement without zinc (control group), 2) the same porridge and multivitamin supplement with 6 mg Zn added to the supplement dose (ZnSuppl group), or 3) the same porridge with added zinc to provide 6 mg Zn per 25 g dry weight of porridge and multivitamin without zinc (ZnFort group).

RESULTS

Mean (±SD) plasma zinc concentration (μg/dL) increased by 4.7 ± 1.6 (P = 0.004) in the ZnSuppl group, which was significantly greater (P = 0.009) than the mean change in the control group (-1.0 ± 1.6; P = 0.51) and in the ZnFort group (-1.8 ± 1.7; P = 0.29). The latter 2 groups did not differ from each other (P = 0.99).

CONCLUSIONS

Plasma zinc concentration increased in children who received daily zinc supplementation for 15 d but not in those who received a zinc-fortified complementary food containing a similar amount of zinc. Additional longer-term studies are needed to assess the effect of zinc-fortification programs on zinc-related functional outcomes and the usefulness of plasma zinc as a biomarker of program effect. This trial was registered at www.clinicaltrials.gov as study NCT0094398.

Nutritional status of preschool Senegalese children: long-term effects of early severe malnutrition

The prevalence of malnutrition remains high in many developing countries. However, data relating to the long-term effects of severe malnutrition, specifically, serum levels of biochemical indicators of nutritional status, are still scarce in the literature. Hence the present study aimed to investigate the nutritional, biological and growth status of Senegalese preschool children previously hospitalised for severe malnutrition. The study involved twenty-four 7-year-old children who had suffered from marasmus 5 years earlier, twenty-four siblings living in the same household, and nineteen age-matched children living in the centre of Dakar. The siblings were of similar age to the post-marasmic children. Anthropometry, serum biochemical indicators of nutritional status, growth factors, and haematological and mineral parameters were measured. The prevalence of stunting and wasting was the same in the post-marasmic children as in the siblings. Body-fat and fat-free-mass (FFM) deficits in both groups were corroborated by abnormally low concentrations of transthyretin, osteocalcin, insulin-like growth factor (IGF)-1, and insulin-like growth factor-binding protein (IGFBP)-3. FFM was positively and significantly correlated with concentrations of IGF-1 and IGFBP-3. In the post-marasmic children, height for age was also correlated with IGF-1. Of the post-marasmic children, 53 % had Fe-deficiency anaemia, as did 35 % of the siblings and 29 % of the controls. No significant associations were found between the serum concentrations of Ca, Cu, K, Mg, Na, P, Se, Zn and growth retardation. At 5 years after nutritional rehabilitation, the post-marasmic children remained stunted with nutritional indices significantly lower than the control children. However, these children were doing as well as their siblings except for minor infections.

A microparticle enhanced nephelometric immunoassay (Nephelia) applied to thymulin measurement

This article describes a microparticle enhanced nephelometric immunoassay (Nephelia) applied to the quantification of the thymic peptide hormone thymulin. Nephelia uses antibody recognition by the antithymulin antiserum in a competitive reaction between free thymulin and thymulin bound to the microspheres. The binding between microsphere and thymulin is achieved with the aid of a protein carrier. The sensitivity of the competitive reaction varied with the protein carrier and the antiserum sample. The most efficient reaction was obtained with the thymulin-metallothionein-microsphere conjugates; as little as 5 pg/ml of thymulin could be detected. In adult human serum or in its ultra-filtrate, spiked synthetic thymulin was totally recovered. Measurement of thymulin in serum or ultra-filtrate samples demonstrated the presence of interference from molecules in the serum. Nephelia led to the same conclusions as those reported with other methods and performs as well, and is more simple to use than radio- or enzymo-immunoassays for thymulin measurement.