Mechanisms behind decreased endogenous glucose production in malnourished children

Metabolomic changes in severe acute malnutrition suggest hepatic oxidative stress: a secondary analysis

Severe acute malnutrition (SAM), due to poor energy and/or protein intake, is associated with poor growth, depressed immune function, and long-term impacts on metabolic function. As the liver is a major metabolic organ and malnutrition poses metabolic stress, we hypothesize that SAM will be associated with alterations in the hepatic metabolome reflective of oxidative stress, gluconeogenesis, and ketogenesis. Thus, the purpose of this secondary analysis was to understand how SAM alters hepatic metabolism using a piglet model. Weanling piglets were feed either a reference (REF) or protein-energy deficient diet (MAL) for 5 weeks. After dietary treatment MAL piglets were severely underweight (weight-for-age Z-score of -3.29, Welch's t test, P = .0007), moderately wasted (weight-for-length Z-score of-2.49, Welch's t test, P = .003), and tended toward higher hepatic triglyceride content (Welch's t test, P = .07). Hematologic and blood biochemical measurements were assessed at baseline and after dietary treatment. The hepatic metabolome was investigated using ¹H-NMR spectroscopy. Hepatic concentrations of betaine, cysteine, and glutathione tended to be lower in MAL (Welch's t test with FDR correction, P < .1), while inosine, lactate, and methionine sulfoxide concentrations were higher in MAL (inosine: P = .0448, lactate: P = .0258, methionine sulfoxide: P = .0337). These changes suggest that SAM is associated with elevated hepatic oxidative stress, increased gluconeogenesis, and alterations in 1-carbon metabolism.

Childhood severe acute malnutrition is associated with metabolic changes in adulthood

BACKGROUND

Severe acute malnutrition (SAM) is a major contributor to global mortality in children under 5 years. Mortality has decreased; however, the long-term cardiometabolic consequences of SAM and its subtypes, severe wasting (SW) and edematous malnutrition (EM), are not well understood. We evaluated the metabolic profiles of adult SAM survivors using targeted metabolomic analyses.

METHODS

This cohort study of 122 adult SAM survivors (SW = 69, EM = 53) and 90 age-, sex-, and BMI-matched community participants (CPs) quantified serum metabolites using direct flow injection mass spectrometry combined with reverse-phase liquid chromatography. Univariate and sparse partial least square discriminant analyses (sPLS-DAs) assessed differences in metabolic profiles and identified the most discriminative metabolites.

RESULTS

Seventy-seven metabolite variables were significant in distinguishing between SAM survivors (28.4 ± 8.8 years, 24.0 ± 6.1 kg/m²) and CPs (28.4 ± 8.9 years, 23.3 ± 4.4 kg/m²) (mean ± SDs) in univariate and sPLS-DA models. Compared with CPs, SAM survivors had less liver fat; higher branched-chain amino acids (BCAAs), urea cycle metabolites, and kynurenine/tryptophan (KT) ratio (P < 0.001); and lower β-hydroxybutyric acid and acylcarnitine/free carnitine ratio (P < 0.001), which were both associated with hepatic steatosis (P < 0.001). SW and EM survivors had similar metabolic profiles as did stunted and nonstunted SAM survivors.

CONCLUSION

Adult SAM survivors have distinct metabolic profiles that suggest reduced β-oxidation and greater risk of type 2 diabetes (BCAAs, KT ratio, urea cycle metabolites) compared with CPs. This indicates that early childhood SAM exposure has long-term metabolic consequences that may worsen with age and require targeted clinical management.

FUNDING

Health Research Council of New Zealand, Caribbean Public Health Agency, Centre for Global Child Health at the Hospital for Sick Children. DST is an Academic Fellow and a Restracomp Fellow at the Centre for Global Child Health. GBG is a postdoctoral fellow of the Research Foundation Flanders.

Linking nutrient sensing and gene expression in Plasmodium falciparum blood-stage parasites

Malaria is one of the most life-threatening infectious diseases worldwide, caused by infection of humans with parasites of the genus Plasmodium. The complex life cycle of Plasmodium parasites is shared between two hosts, with infection of multiple cell types, and the parasite needs to adapt for survival and transmission through significantly different metabolic environments. Within the blood-stage alone, parasites encounter changing levels of key nutrients, including sugars, amino acids, and lipids, due to differences in host dietary nutrition, cellular tropism, and pathogenesis. In this review, we consider the mechanisms that the most lethal of malaria parasites, Plasmodium falciparum, uses to sense nutrient levels and elicit changes in gene expression during blood-stage infections. These changes are brought about by several metabolic intermediates and their corresponding sensor proteins. Sensing of distinct nutritional signals can drive P. falciparum to alter the key blood-stage processes of proliferation, antigenic variation, and transmission.

Dysglycemia in Children with Severe Acute Malnutrition: A Systematic Review and Meta-Analysis

Dysglycemia is a common complication of severe acute malnutrition (SAM) in children. Its prevalence and impact on short- and long-term outcomes are not well described. This systematic review was undertaken to review the available evidence on dysglycemia (either hypo- or hyperglycemia) in hospitalized children with SAM. The 2 primary objectives of this systematic review were to understand the prevalence of hypoglycemia and hyperglycemia in children with SAM. A secondary objective was to understand the relation between dysglycemia and clinical outcomes like mortality in children with SAM. MEDLINE was searched with terms related to children, SAM, and dysglycemia. A meta-analysis of proportions was completed to determine the hypoglycemia prevalence and a standard meta-analysis was done to determine the relation between hypoglycemia and mortality. The certainty of the evidence was evaluated using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. A total of 2148 articles were identified in the database search of which 16 met the inclusion criteria for the systematic review based on screening done by multiple reviewers. The overall prevalence of hypoglycemia in SAM across studies based on the meta-analysis of proportions was 9% (95% CI: 7%, 12%; I2 = 92%). Meta-analysis results showed that hypoglycemia was associated with a higher chance of mortality during hospitalization in children with SAM (OR: 4.29; 95% CI: 3.04, 6.05; I2 = 0%). According to the GRADE evaluation, the certainty of the evidence for the prevalence of hypoglycemia was low and for hyperglycemia was very low. For the relation between hypoglycemia and mortality, the certainty of the evidence was moderate. A meta-analysis was not carried out for the prevalence of hyperglycemia due to the wide range of definitions used for across studies, but the prevalence ranged from 2% to 38% in the literature. This systematic review highlights the need for further work in this area to include serial glucose measurements to understand the clinical importance of dysglycemia during hospitalization in children with SAM.

Impact of Treatment with RUTF on Plasma Lipid Profiles of Severely Malnourished Pakistani Children

(1) Background: Little is known on impacts of ready-to-use therapeutic food (RUTF) treatment on lipid metabolism in children with severe acute malnutrition (SAM). (2) Methods: We analyzed glycerophospholipid fatty acids (FA) and polar lipids in plasma of 41 Pakistani children with SAM before and after 3 months of RUTF treatment using gas chromatography and flow-injection analysis tandem mass spectrometry, respectively. Statistical analysis was performed using univariate, multivariate tests and evaluated for the impact of age, sex, breastfeeding status, hemoglobin, and anthropometry. (3) Results: Essential fatty acid (EFA) depletion at baseline was corrected by RUTF treatment which increased EFA. In addition, long-chain polyunsaturated fatty acids (LC-PUFA) and the ratio of arachidonic acid (AA)/linoleic acid increased reflecting greater EFA conversion to LC-PUFA, whereas Mead acid/AA decreased. Among phospholipids, lysophosphatidylcholines (lyso.PC) were most impacted by treatment; in particular, saturated lyso.PC decreased. Higher child age and breastfeeding were associated with great decrease in total saturated FA (ΣSFA) and lesser decrease in monounsaturated FA and total phosphatidylcholines (ΣPC). Conclusions: RUTF treatment improves EFA deficiency in SAM, appears to enhance EFA conversion to biologically active LC-PUFA, and reduces lipolysis reflected in decreased ΣSFA and saturated lyso.PC. Child age and breastfeeding modify treatment-induced changes in ΣSFA and ΣPC.

Metabolomics in plasma of Malawian children 7 years after surviving severe acute malnutrition: "ChroSAM" a cohort study

BACKGROUND

More children are now surviving severe acute malnutrition (SAM), but evidence suggests that early-life malnutrition is associated with increased risk of long-term cardio-metabolic disorders. To better understand potential mechanisms, we studied the metabolite profiles of children seven years after treatment for SAM.

METHODS

We followed-up children (n = 352) treated for SAM in 2006-2007, at Queen Elizabeth Central Hospital, in Malawi. Using nuclear magnetic resonance spectroscopy, tandem mass spectrometry and enzyme-linked immunosorbent assay, we measured circulating metabolites in fasting blood in a subset of SAM survivors (n = 69, 9·6 ± 1·6 years), siblings (n = 44, 10·5 ± 2·7 years), and age and sex-matched community controls (n = 37, 9·4 ± 1·8 years). Data were analysed using univariate and sparse partial least square (sPLS) methods. Differences associated with SAM survival, oedema status, and anthropometry were tested, adjusting for age, sex, HIV, and wealth index.

FINDINGS

Based on 194 measured metabolites, the profiles of SAM survivors were similar to those of siblings and community controls. IGF1, creatinine, and FGF21, had loading values >0·3 and ranked stably in the top 10 distinguishing metabolites, but did not differ between SAM survivors and controls with univariate analysis. Current stunting was associated with IGF1 (β = 15·2, SE = 3·5, partial R2 = 12%, p < 0·0001) and this relationship could be influenced by early childhood SAM (β = 17·4, SE = 7·7, partial R2 = 2·8%, p = 0·025). No metabolites were associated with oedema status, duration of hospital stay, anthropometry measured during hospitalization, nor with changes in anthropometry since hospitalization.

INTERPRETATION

In this group of survivors, SAM was not associated with longer-term global metabolic changes 7 years after treatment. However, SAM may influence the relationship between current stunting and IGF1. Further risk markers for NCDs in SAM survivors may only be revealed by direct metabolic challenge or later in life.

Gut Microbiota Alteration is Characterized by a Proteobacteria and Fusobacteria Bloom in Kwashiorkor and a Bacteroidetes Paucity in Marasmus

Kwashiorkor and marasmus are considered to be two different clinical diseases resulting from severe malnutrition, but this distinction has been questioned. In a previous study comparing children with kwashiorkor and healthy children from Niger and Senegal, we found a dramatic gut microbiota alteration with a predominant depletion of anaerobes and enrichment in Proteobacteria and Fusobacteria in kwashiorkor. However, it remained unknown whether this association was related to malnutrition or was a specific feature of kwashiorkor. In this continuation study, we added 7 new marasmus subjects and 71,162 new colonies from the same countries. Our results showed that, compared to marasmus, the kwashiorkor gut microbiota was characterized by an increased proportion of Proteobacteria (culturomics, Marasmus 5.0%, Kwashiorkor 16.7%, p < 0.0001; metagenomics, Marasmus 14.7%, Kwashiorkor 22.0%, p = 0.001), but there was a decreased proportion of Bacteroidetes in marasmus (culturomics, Marasmus 0.8%, Kwashiorkor 6.5%, p = 0.001; metagenomics, Marasmus 5.4%, Kwashiorkor 7.0%, p = 0.03). Fusobacterium was more frequently cultured from kwashiorkor. All detected potential pathogenic species were enriched in the kwashiorkor gut microbiota. These results provide a biological basis to support the usage of an antibiotic therapy more effective in suppressing the overgrowth of bacterial communities resistant to penicillin, combined with antioxidants and probiotics for nutritional recovery therapies, particularly for kwashiorkor.

Prevalence and outcome of stress hyperglycaemia among severely malnourished children admitted to Mulago referral and teaching hospital in Kampala, Uganda

Background

Stress hyperglycaemia is a transient increase in blood glucose level during stressful events and is common in critically ill children. Several studies have demonstrated increased risk of mortality in these children. There is paucity of information on this subject in sub Saharan Africa.The aim of this study was to describe the prevalence, outcome and factors associated with stress hyperglycaemia among children with severe acute malnutrition (SAM) admitted to the Mwanamugimu nutrition unit of Mulago hospital in Uganda.

Methods

This study was conducted from August 2015 to March 2016 at the Mwanamugimu nutrition unit of Mulago hospital among severely malnourished children aged 1 to 60 months. Random blood sugar levels were measured. Stress hyperglycaemia was considered as a random blood sugar > 150 mg/dl. The final outcome was ascertained at death or discharge. Statistical analysis was done using the Chi square test and logistic regression.

Results

Two hundred and thirty-five children were enrolled of whom 50% were girls. The median age was 5.1 months (range 1-60 months). Stress hyperglycaemia was present in 16.6% of the 235 participants. Several factors were significantly associated with stress hyperglycaemia at bivariate analysis; but on logistic regression, only presence of oral sores was associated with stress hyperglycaemia: (Odds ratio 2.61; 95% CI 1.02-6.65).Mortality was higher among children with stress hyperglycaemia (56.4%) compared to (12.8%) in the non-hyperglycaemic group: OR 8.75; 95% CI 4.09-18.70).

Conclusion

The prevalence of stress hyperglycaemia was 16.6% and was associated with high mortality. It is important to monitor blood glucose levels of severely malnourished children. Hitherto, the main concern among severely malnourished children has been hypoglycaemia. Innovative ways of preventing and managing stress hyperglycaemia among these children are urgently needed.

Long-term metabolic effects of malnutrition: Liver steatosis and insulin resistance following early-life protein restriction

Early postnatal-life malnutrition remains prevalent globally, and about 45% of all child deaths are linked to malnutrition. It is not clear whether survivors of childhood malnutrition suffer from long-term metabolic effects, especially when they are later in life exposed to a fat and carbohydrate rich obesogenic diet. The lack of knowledge around this dietary “double burden” warrants studies to understand the long-term consequences of children previously exposed to malnutrition. We hypothesized that an early-life nutritional insult of low protein consumption in mice would lead to long-term metabolic disturbances that would exacerbate the development of diet-induced insulin resistance and non-alcoholic fatty liver disease (NAFLD). We investigated the effects of feeding a low protein diet (4% wt/wt) immediately after weaning for four weeks and subsequent feeding of a high carbohydrate high fat feeding for 16 weeks on metabolic function and development of NAFLD. Mice exposed to early-life protein restriction demonstrated a transient glucose intolerance upon recovery by regular chow diet feeding. However, protein restriction after weaning in mice did not exacerbate an obesogenic diet-induced insulin resistance or progression to NAFLD. These data suggest that transient protein restriction in early-life does not exacerbate an obesogenic diet-induced NAFLD and insulin resistance.

Severe childhood malnutrition

The main forms of childhood malnutrition occur predominantly in children <5 years of age living in low-income and middle-income countries and include stunting, wasting and kwashiorkor, of which severe wasting and kwashiorkor are commonly referred to as severe acute malnutrition. Here, we use the term 'severe malnutrition' to describe these conditions to better reflect the contributions of chronic poverty, poor living conditions with pervasive deficits in sanitation and hygiene, a high prevalence of infectious diseases and environmental insults, food insecurity, poor maternal and fetal nutritional status and suboptimal nutritional intake in infancy and early childhood. Children with severe malnutrition have an increased risk of serious illness and death, primarily from acute infectious diseases. International growth standards are used for the diagnosis of severe malnutrition and provide therapeutic end points. The early detection of severe wasting and kwashiorkor and outpatient therapy for these conditions using ready-to-use therapeutic foods form the cornerstone of modern therapy, and only a small percentage of children require inpatient care. However, the normalization of physiological and metabolic functions in children with malnutrition is challenging, and children remain at high risk of relapse and death. Further research is urgently needed to improve our understanding of the pathophysiology of severe malnutrition, especially the mechanisms causing kwashiorkor, and to develop new interventions for prevention and treatment.

Metabolomic Changes in Serum of Children with Different Clinical Diagnoses of Malnutrition

Background: Mortality in children with severe acute malnutrition (SAM) remains high despite standardized rehabilitation protocols. Two forms of SAM are classically distinguished: kwashiorkor and marasmus. Children with kwashiorkor have nutritional edema and metabolic disturbances, including hypoalbuminemia and hepatic steatosis, whereas marasmus is characterized by severe wasting. The metabolic changes underlying these phenotypes have been poorly characterized, and whether homeostasis is achieved during hospital stay is unclear.

Objectives: We aimed to characterize metabolic differences between children with marasmus and kwashiorkor at hospital admission and after clinical stabilization and to compare them with stunted and nonstunted community controls.

Methods: We studied children aged 9–59 mo from Malawi who were hospitalized with SAM (n = 40; 21 with kwashiorkor and 19 with marasmus) or living in the community (n = 157; 78 stunted and 79 nonstunted). Serum from patients with SAM was obtained at hospital admission and 3 d after nutritional stabilization and from community controls. With the use of targeted metabolomics, 141 metabolites, including amino acids, biogenic amines, acylcarnitines, sphingomyelins, and phosphatidylcholines, were measured.

Results: At admission, most metabolites (128 of 141; 91%) were lower in children with kwashiorkor than in those with marasmus, with significant differences in several amino acids and biogenic amines, including those of the kynurenine-tryptophan pathway. Several phosphatidylcholines and some acylcarnitines also differed. Patients with SAM had profiles that were profoundly different from those of stunted and nonstunted controls, even after clinical stabilization. Amino acids and biogenic amines generally improved with nutritional rehabilitation, but most sphingomyelins and phosphatidylcholines did not.

Conclusions: Children with kwashiorkor were metabolically distinct from those with marasmus, and were more prone to severe metabolic disruptions. Children with SAM showed metabolic profiles that were profoundly different from stunted and nonstunted controls, even after clinical stabilization. Therefore, metabolic recovery in children with SAM likely extends beyond discharge, which may explain the poor long-term outcomes in these children. This trial was registered at isrctn.org as ISRCTN13916953.

Impaired Bile Acid Homeostasis in Children with Severe Acute Malnutrition

Objective

Severe acute malnutrition (SAM) is a major cause of mortality in children under 5 years and is associated with hepatic steatosis. Bile acids are synthesized in the liver and participate in dietary fat digestion, regulation of energy expenditure, and immune responses. The aim of this work was to investigate whether SAM is associated with clinically relevant changes in bile acid homeostasis.

Design

An initial discovery cohort with 5 healthy controls and 22 SAM-patients was used to identify altered bile acid homeostasis. A follow up cohort of 40 SAM-patients were then studied on admission and 3 days after clinical stabilization to assess recovery in bile acid metabolism. Recruited children were 6–60 months old and admitted for SAM in Malawi. Clinical characteristics, feces and blood were collected on admission and prior to discharge. Bile acids, 7α-hydroxy-4-cholesten-3-one (C4) and FGF-19 were quantified.

Results

On admission, total serum bile acids were higher in children with SAM than in healthy controls and glycine-conjugates accounted for most of this accumulation with median and interquartile range (IQR) of 24.6 μmol/L [8.6–47.7] compared to 1.9 μmol/L [1.7–3.3] (p = 0.01) in controls. Total serum bile acid concentrations did not decrease prior to discharge. On admission, fecal conjugated bile acids were lower and secondary bile acids higher at admission compared to pre- discharge, suggesting increased bacterial conversion. FGF19 (Fibroblast growth factor 19), a marker of intestinal bile acid signaling, was higher on admission and was associated with decreased C4 concentrations as a marker of bile acid synthesis. Upon recovery, fecal calprotectin, a marker of intestinal inflammation, was lower.

Conclusion

SAM is associated with increased serum bile acid levels despite reduced synthesis rates. In SAM, there tends to be increased deconjugation of bile acids and conversion from primary to secondary bile acids, which may contribute to the development of liver disease.

High Mortality Risk in Hypoglycemic and Dysglycemic Children Admitted at a Referral Hospital in a Non Malaria Tropical Setting of a Low Income Country

INTRODUCTION

Hypoglycemia is a recognized feature of severe malaria but its diagnosis and management remain problematic in resource-limited settings. There is limited data on the burden and prognosis associated with glycemia dysregulation in non-neonate children in non-malaria areas. We prospectively assessed the abnormal blood glucose prevalence and the outcome and risk factors of deaths in critically ill children admitted to a national referral hospital in Laos.

METHODS

Consecutive children (1 month-15 years) admitted to the pediatric ward of Mahosot hospital, were categorized using the integrated management of childhood illness (IMCI). Blood glucose was assessed once on admission through a finger prick using a bedside glucometer. Glycemia levels: hypoglycemia: < 2.2 mmol/L (< 40 mg⁄ dl), low glycemia: 2.2-4.4 mmol/L (40-79 mg⁄ dl), euglycemia: 4.4-8.3 mmol/L (80-149 mg⁄ dl), and hyperglycemia: > 8.3 mmol/L (≥150 mg⁄ dl), were related to the IMCI algorithm and case fatality using univariate and multivariate analysis.

RESULTS

Of 350 children, 62.2% (n = 218) were severely ill and 49.1% (n = 172) had at least one IMCI danger sign. A total of 15 (4.2%, 95%CI: 2.4-6.9) had hypoglycemia, 99 (28.2%, 95%CI: 23.6-33.3) low glycemia, 201 (57.4%, 95% CI: 52.0-62.6) euglycemia and 35 (10.0%, 95% CI: 7.0-13.6) hyperglycemia. Hypoglycemia was associated with longer fasting (p = 0.001) and limited treatment before admission (p = 0.09). Hypoglycemia and hyperglycemia were associated with hypoxemia (SaO2) (p = 0.001). A total of 21 (6.0%) of the children died: 66.6% with hypoglycemic, 6.0% with low glycemic, 5.7% with hyperglycemic and 1.4% with euglycemic groups. A total of 9 (2.5%) deaths occurred during the first 24 hours of admission and 5 (1.7%) within 3 days of hospital discharge. Compared to euglycemic children, hypoglycemic and low glycemic children had a higher rate of early death (20%, p<0.001 and 5%, p = 0.008; respectively). They also had a higher risk of death (OR: 132; 95%CI: 29.0-596.5; p = 0.001; and OR: 4.2; 95%CI: 1.1-15.6; p = 0.02; respectively). In multivariate analyses, hypoglycemia (OR: 197; 95%CI: 33-1173.9), hypoxemia (OR: 5.3; 95%CI: 1.4-20), presence of hepatomegaly (OR: 8.7; 95%CI: 2.0-37.6) and having an illiterate mother (OR: 25.9; 95%CI: 4.2-160.6) were associated with increased risk of death.

CONCLUSION

Hypoglycemia is linked with a high risk of mortality for children in non malaria tropical settings. Blood sugar should be monitored and treatment provided for sick children, especially with danger signs and prolonged fasting. Further evaluations of intervention using thresholds including low glycemia is recommended in resource-limited settings. Research is also needed to determine the significance, prognosis and care of hyperglycemia.

Hypoglycemia and Risk Factors for Death in 13 Years of Pediatric Admissions in Mozambique

Hypoglycemia is a life-threatening complication of several diseases in childhood. We describe the prevalence and incidence of hypoglycemia among admitted Mozambican children, establishing its associated risk factors. We retrospectively reviewed clinical data of 13 years collected through an ongoing systematic morbidity surveillance in Manhiça District Hospital in rural Mozambique. Logistic regression was used to identify risk factors for hypoglycemia and death. Minimum community-based incidence rates (MCBIRs) for hypoglycemia were calculated using data from the demographic surveillance system. Of 49,089 children < 15 years hospitalized in Manhiça District Hospital, 45,573 (92.8%) had a glycemia assessment on admission. A total of 1,478 children (3.2%) presented hypoglycemia (< 3 mmol/L), of which about two-thirds (972) were with levels < 2.5 mmol/L. Independent risk factors for hypoglycemia on admission and death among hypoglycemic children included prostration, unconsciousness, edema, malnutrition, and bacteremia. Hypoglycemic children were significantly more likely to die (odds ratio [OR] = 7.11; P < 0.001), with an associated case fatality rate (CFR) of 19.3% (245/1,267). Overall MCBIR of hypoglycemia was 1.57 episodes/1,000 child years at risk (CYAR), significantly decreasing throughout the study period. Newborns showed the highest incidences (9.47 episodes/1,000 CYAR, P < 0.001). Hypoglycemia remains a hazardous condition for African children. Symptoms and signs associated to hypoglycemia should trigger the verification of glycemia and the implementation of life-saving corrective measures.

Essential amino acid transporter Lat4 (Slc43a2) is required for mouse development

Amino acid (AA) uniporter Lat4 (Slc43a2) mediates facilitated diffusion of branched-chain AAs, methionine and phenylalanine, although its physiological role and subcellular localization are not known. We report that Slc43a2 knockout mice were born at expected Mendelian frequency but displayed an ∼10% intrauterine growth retardation and low amniotic fluid AAs, suggesting defective transplacental transport. Postnatal growth was strongly reduced, with premature death occurring within 9 days such that further investigations were made within 3 days of birth. Lat4 immunofluorescence showed a strong basolateral signal in the small intestine, kidney proximal tubule and thick ascending limb epithelial cells of wild-type but not Slc43a2 null littermates and no signal in liver and skeletal muscle. Experiments using Xenopus laevis oocytes demonstrated that Lat4 functioned as a symmetrical low affinity uniporter with a K₀.₅ of ∼5 mm for both in- and efflux. Plasma AA concentration was decreased in Slc43a2 null pups, in particular that of non-essential AAs alanine, serine, histidine and proline. Together with an increased level of plasma long chain acylcarnitines and a strong alteration of liver gene expression, this indicates malnutrition. Attempts to rescue pups by decreasing the litter size or by nutrients injected i.p. did not succeed. Radioactively labelled leucine but not lysine given per os accumulated in the small intestine of Slc43a2null pups, suggesting the defective transcellular transport of Lat4 substrates. In summary, Lat4 is a symmetrical uniporter for neutral essential AAs localizing at the basolateral side of (re)absorbing epithelia and is necessary for early nutrition and development.

Challenges in the Management of HIV-Infected Malnourished Children in Sub-Saharan Africa

Infection with HIV, and oftentimes coinfection with TB, complicates the care of severely malnourished children in sub-Saharan Africa. These superimposed infections challenge clinicians faced with a population of malnourished children for whose care evidence-based guidelines have not kept up. Even as the care of HIV-uninfected malnourished children has improved dramatically with the advent of community-based care and even as there are hopeful signs that the HIV epidemic may be stabilizing or ameliorating, significant gaps remain in the care of malnourished children with HIV. Here we summarize what is currently known, what remains unknown, and what remains challenging about how to treat severely malnourished children with HIV and TB.