BODY COMPOSITION IN SEVERE INFANTILE MALNUTRITION

Branched-chain α-ketoacid dehydrogenase deficiency (maple syrup urine disease): Treatment, biomarkers, and outcomes

Over the past three decades, we studied 184 individuals with 174 different molecular variants of branched-chain α-ketoacid dehydrogenase activity, and here delineate essential clinical and biochemical aspects of the maple syrup urine disease (MSUD) phenotype. We collected data about treatment, survival, hospitalization, metabolic control, and liver transplantation from patients with classic (i.e., severe; n = 176), intermediate (n = 6) and intermittent (n = 2) forms of MSUD. A total of 13,589 amino acid profiles were used to analyze leucine tolerance, amino acid homeostasis, estimated cerebral amino acid uptake, quantitative responses to anabolic therapy, and metabolic control after liver transplantation. Standard instruments were used to measure neuropsychiatric outcomes. Despite advances in clinical care, classic MSUD remains a morbid and potentially fatal disorder. Stringent dietary therapy maintains metabolic variables within acceptable limits but is challenging to implement, fails to restore appropriate concentration relationships among circulating amino acids, and does not fully prevent cognitive and psychiatric disabilities. Liver transplantation eliminates the need for a prescription diet and safeguards patients from life-threatening metabolic crises, but is associated with predictable morbidities and does not reverse pre-existing neurological sequelae. There is a critical unmet need for safe and effective disease-modifying therapies for MSUD which can be implemented early in life. The biochemistry and physiology of MSUD and its response to liver transplantation afford key insights into the design of new therapies based on gene replacement or editing.

Acceptability and efficacy of ready-to-use therapeutic food using soy protein isolate in under-5 children suffering from severe acute malnutrition in Bangladesh: a double-blind randomized non-inferiority trial

BACKGROUND AND OBJECTIVE

Globally, around 20 million children suffer from severe acute malnutrition (SAM). Identifying a more economical treatment for those affected has the potential to make treatment more available and improve prognosis for recovery and future health.

DESIGN/METHODS

The double-blind randomized study compared taste acceptability (measured by the eagerness to eat) and efficacy of soy-based RUTF (S-RUTF) with milk-based RUTF (M-RUTF) in 6- to 59-month-old children suffering from SAM (WHZ < -3) at icddr,b, in Bangladesh. These SAM children were enrolled in the study after completion of their stabilization phase of treatment. Tolerance of test-RUTF was also tested during the efficacy trial.

RESULTS

The cross-over taste acceptability study, conducted in 36 children, revealed similar results between products and an absence of side effects. The efficacy trial enrolled 260 children (130, each group) with similar baseline characteristics, including mean ± SD age 15.0 ± 8.0 months, WHZ - 3.41 ± 0.40 and mid-upper arm circumference (MUAC) 11.1 ± 0.7 cm. The features at the end of study by RUTF group were (in S-RUTF vs. M-RUTF, respectively): total days from enrollment: 44 ± 34 versus 39 ± 30; weight gain (kg): 0.698 ± 0.438 versus 0.741 ± 0.381 and rate of weight gain (g/kg/d): 3.9 ± 3.2 versus 5.2 ± 4.6; MUAC gain (cm): 0.9 ± 0.7 versus 0.9 ± 0.6; and improvement of WHZ: 1.12 ± 0.82 versus 1.22 ± 0.68 (all data were man ± SD and none were significantly different between the groups). At enrollment and the end of intervention, the body composition [total body water (TBW): 70.3 ± 3.2 vs. 69.9 ± 3.5%, and fat: 11.0 ± 4.0 vs.11.5 ± 4.3% at baseline; and TBW: 65.5 ± 4.1 vs. 65.9 ± 4.6%; and fat: 16.8 ± 5.2 vs. 16.2 ± 5.8% in S-RUTF and M-RUTF group, respectively] was found similar. Moreover, the increment of total TBW, FM, and FFM was also observed similar between the groups.

CONCLUSIONS

This is the first randomized trial comparing S-RUTF using soy protein isolate with milk-based RUTF including comparison of body composition. S-RUTF was found equally acceptable as of milk-based RUTF without any adverse event. Children receiving S-RUTF showed similar pattern of changes in anthropometric indices, and body composition as of milk-based RUTF. Greater number of SAM children can be managed in the community with comparatively low-cost soy-based RUTF.

TRIAL REGISTRATION

NCT01634009.

Genome-wide RNAi Screen for Fat Regulatory Genes in C. elegans Identifies a Proteostasis-AMPK Axis Critical for Starvation Survival

Organisms must execute metabolic defenses to survive nutrient deprivation. We performed a genome-wide RNAi screen in Caenorhabditis elegans to identify fat regulatory genes indispensable for starvation resistance. Here, we show that opposing proteostasis pathways are principal determinants of starvation survival. Reduced function of cytoplasmic aminoacyl tRNA synthetases (ARS genes) increases fat mass and extends starvation survival, whereas reduced proteasomal function reduces fat and starvation survival. These opposing pathways converge on AMP-activated protein kinase (AMPK) as the critical effector of starvation defenses. Extended starvation survival in ARS deficiency is dependent upon increased proteasome-mediated activation of AMPK. When the proteasome is inhibited, neither starvation nor ARS deficiency can fully activate AMPK, leading to greatly diminished starvation survival. Thus, activity of the proteasome and AMPK are mechanistically linked and highly correlated with starvation resistance. Conversely, aberrant activation of the proteostasis-AMPK axis during nutritional excess may have implications for obesity and cardiometabolic diseases.

Protein nutrition and wound healing

In normal young men, in whom the calorie requirements are fully met, an intake of about 50 g protein per day promotes nitrogen balance, and little additional storage results even from much larger protein intakes (Galloway &amp; Spector, 1954). Chittenden maintained that an adult who adopted the intake of 120 g per day suggested by Voit, or who advised others to do so, was ‘encouraging individual and racial suicide’ (Cathcart, 1912), and the animal experiments of Ross show that by all objective criteria, except that of body-weight, the rats whose dietary intake is restricted fare better than those allowed unlimited quantities of a diet of good quality (Ross, 1961; Ross &amp; Bras, 1965).

Bioimpedance index for measurement of total body water in severely malnourished children: Assessing the effect of nutritional oedema

BACKGROUND & OBJECTIVES

Restoration of body composition indicates successful management of severe acute malnutrition (SAM). Bioimpedance (BI) index (height(2)/resistance) is used to predict total body water (TBW) but its performance in SAM, especially with oedema, requires further investigation.

SUBJECTS/METHODS

Children with SAM (mid-arm circumference <11.0 cm or weight-for-height <70% of median of NCHS reference and/or nutritional oedema) admitted to Jimma University Hospital were included. Tetrapolar-whole-body impedance (Z), resistance (R) and reactance (Xc) were measured at 50 and 200 kHzs. Pre- and post-deuterium dose saliva samples were analysed using isotope-ratio mass spectrometry. TBW was regressed on H(2)/Z. Xc and R were height (H)-indexed, and Xc/H plotted against R/H.

RESULTS

Thirty five children (16 non-oedematous and 19 oedematous) with median (interquartile range) age of 42 (26-54) months were studied. Height-for-age z-score (mean ± SD) was low in both non-oedematous (-3.9 ± 2.8) and oedematous (-3.6 ± 1.7) children. Oedematous children had lower BI parameters than non-oedematous (p < 0.001) and hence higher H(2)/Z for a given amount of TBW. At both 50 and 200 kHz, association between H(2)/Z and TBW was stronger in non-oedematous children than oedematous (60% higher coefficient of determination and 20% lower standard error of estimate). Intercepts and regression estimates at 50 and 200 kHz were similar, in both oedematous and non-oedematous children.

CONCLUSIONS

In children with oedematous SAM, BI index was weak in predicting TBW. Moreover, predicted TBWs at 200 kHz and 50 kHz did not differ and hence BI measurement at 50 kHz is still practical for TBW estimation.

Safety, efficacy and physiological actions of a lysine-free, arginine-rich formula to treat glutaryl-CoA dehydrogenase deficiency: focus on cerebral amino acid influx

Striatal degeneration from glutaryl-CoA dehydrogenase deficiency (glutaric aciduria type 1, GA1) is associated with cerebral formation and entrapment of glutaryl-CoA and its derivatives that depend on cerebral lysine influx. In 2006 we designed a lysine-free study formula enriched with arginine to selectively block lysine transport across cerebral endothelia and thereby limit glutaryl-CoA production by brain. Between 2006 and present, we treated twelve consecutive children with study formula (LYSx group) while holding all other treatment practices constant. Clinical and biochemical outcomes were compared to 25 GA1 patients (PROx group) treated between 1995 and 2005 with natural protein restriction (dietary lysine/arginine ratio of 1.7±0.3 mg:mg). We used published kinetic parameters of the y+and LAT1 blood-brain barrier transporters to model the influx of amino acids into the brain. Arginine fortification to achieve a mean dietary lysine/arginine ratio of 0.7±0.2 mg:mg was neuroprotective. All 12 LYSx patients are physically and neurologically healthy after 28 aggregate patient-years of follow up (current ages 28±21 months) and there were no adverse events related to formula use. This represents a 36% reduction of neurological risk (95% confidence interval 14-52%, p=0.018) that we can directly attribute to altered amino acid intake. During the first year of life, 20% lower lysine intake and two-fold higher arginine intake by LYSx patients were associated with 50% lower plasma lysine, 3-fold lower plasma lysine/arginine concentration ratio, 42% lower mean calculated cerebral lysine influx, 54% higher calculated cerebral arginine influx, 15-26% higher calculated cerebral influx of several anaplerotic precursors (isoleucine, threonine, methionine, and leucine), 50% less 3-hydroxyglutarate excretion, and a 3-fold lower hospitalization rate (0.8 versus 2.3 hospitalizations per patient per year). The relationship between arginine fortification and plasma lysine indicates that transport competition exists at both cerebrovascular and gastrointestinal barriers, suggesting their co-administration is key to efficacy. Monitoring the ratio between lysine and arginine in diet and plasma may prove a useful strategy for treating children with GA1.

The thrifty 'catch-up fat' phenotype: its impact on insulin sensitivity during growth trajectories to obesity and metabolic syndrome

The analyses of large epidemiological databases have suggested that infants and children who show catch-up growth, or adiposity rebound at a younger age, are predisposed to the development of obesity, type 2 diabetes and cardiovascular diseases later in life. The pathophysiological mechanisms by which these growth trajectories confer increased risks for these diseases are obscure, but there is compelling evidence that the dynamic process of catch-up growth per se, which often overlaps with adiposity rebound at a younger age, is characterized by hyperinsulinemia and by a disproportionately higher rate in the recovery of body fat than lean tissue (i.e. preferential 'catch-up fat'). This paper first focuses upon the almost ubiquitous nature of this preferential 'catch-up fat' phenotype across the life cycle as a risk factor for obesity and insulin-related complications - not only in infants and children who experienced catch-up growth after earlier fetal or neonatal growth retardation, or after preterm birth, but also in adults who show weight recovery after substantial weight loss owing to famine, disease-cachexia or periodic dieting. It subsequently reviews the evidence indicating that such preferential catch-up fat is primarily driven by energy conservation (thrifty) mechanisms operating via suppressed thermogenesis, with glucose thus spared from oxidation in skeletal muscle being directed towards de novo lipogenesis and storage in white adipose tissue. A molecular-physiological framework is presented which integrates emerging insights into the mechanisms by which this thrifty 'catch-up fat' phenotype crosslinks with early development of insulin and leptin resistance. In the complex interactions between genetic constitution of the individual, programming earlier in life, and a subsequent lifestyle of energy dense foods and low physical activity, this thrifty 'catch-up fat' phenotype--which probably evolved to increase survival capacity in a hunter-gatherer lifestyle of periodic food shortages--is a central event in growth trajectories to obesity and to diseases that cluster into the insulin resistance (metabolic) syndrome.

Classical maple syrup urine disease and brain development: principles of management and formula design

Branched-chain ketoacid dehydrogenase deficiency results in complex and volatile metabolic derangements that threaten brain development. Treatment for classical maple syrup urine disease (MSUD) should address this underlying physiology while also protecting children from nutrient deficiencies. Based on a 20-year experience managing 79 patients, we designed a study formula to (1) optimize transport of seven amino acids (Tyr, Trp, His, Met, Thr, Gln, Phe) that compete with branched-chain amino acids (BCAAs) for entry into the brain via a common transporter (LAT1), (2) compensate for episodic depletions of glutamine, glutamate, and alanine caused by reverse transamination, and (3) correct deficiencies of omega-3 essential fatty acids, zinc, and selenium widespread among MSUD patients. The formula was enriched with LAT1 amino acid substrates, glutamine, alanine, zinc, selenium, and alpha-linolenic acid (18:3n-3). Fifteen Old Order Mennonite children were started on study formula between birth and 34 months of age and seen at least monthly in the office. Amino acid levels were checked once weekly and more often during illnesses. All children grew and developed normally over a period of 14-33 months. Energy demand, leucine tolerance, and protein accretion were tightly linked during periods of normal growth. Rapid shifts to net protein degradation occurred during illnesses. At baseline, most LAT1 substrates varied inversely with plasma leucine, and their calculated rates of brain uptake were 20-68% below normal. Treatment with study formula increased plasma concentrations of LAT1 substrates and normalized their calculated uptakes into the nervous system. Red cell membrane omega-3 polyunsaturated fatty acids and serum zinc and selenium levels increased on study formula. However, selenium and docosahexaenoic acid (22:6n-3) levels remained below normal. During the study period, hospitalizations decreased from 0.35 to 0.14 per patient per year. There were 28 hospitalizations managed with MSUD hyperalimentation solution; 86% were precipitated by common infections, especially vomiting and gastroenteritis. The large majority of catabolic illnesses were managed successfully at home using 'sick-day' formula and frequent amino acid monitoring. We conclude that the study formula is safe and effective for the treatment of classical MSUD. In principle, dietary enrichment protects the brain against deficiency of amino acids used for protein accretion, neurotransmitter synthesis, and methyl group transfer. Although the pathophysiology of MSUD can be addressed through rational formula design, this does not replace the need for vigilant clinical monitoring, frequent measurement of the complete amino acid profile, and ongoing dietary adjustments that match nutritional intake to the metabolic demands of growth and illness.

Effects of mass and body composition on fasting fuel utilisation in grey seal pups (Halichoerus grypus Fabricius): an experimental study using supplementary feeding

This study used supplementary feeding to test the hypothesis that fuel partitioning during the postweaning fast in grey seal pups is affected by size and composition of energy reserves at weaning, and by extra provisioning. Mass and body composition changes were measured during suckling and fasting to investigate the effect of natural differences in energy reserves at weaning on subsequent allocation of fat and protein to energy use. We fed seven pups for 5 days after weaning, to investigate the effect of increased fuel availability, and particularly protein, on fuel utilisation. After correcting for protein used during the moult, the proportional contribution of fat was 86-99% of total energy use. Pups with greater energy reserves, i.e. those that were heavier and fatter at weaning, had higher rates of fat and energy use. There was no significant relationship between adiposity at weaning and proportional contribution of fat to energy use, perhaps due to a limited sample size or range of body masses and adiposity. Supplemented individuals used energy, specifically fat, much faster and utilised proportionally less of their endogenous protein by departure than non-supplemented individuals. Fat metabolism contributed a similar percentage to daily energy use in both groups. These findings show that pups spare protein, even when energy use is dramatically increased. Pups that receive greater maternal provisioning and lay down more protein may have increased survival chances at sea. This study highlights the importance of protein reserves in first year survival of grey seal pups.

Effects of dietary protein restriction on nephron number in the mouse

In rats, maternal protein restriction reduces nephron endowment and often leads to adult hypertension. Sex differences in these responses have been identified. The molecular and genetic bases of these phenomena can best be identified in a mouse model, but effects of maternal protein restriction on kidney development have not been examined in mice. Therefore, we determined how combined prenatal and postnatal protein restriction in mice affects organ weight, glomerular number and dimensions, and renal expression of angiotensin receptor mRNA, in both male and female offspring. C57/BL6/129sv mice received either a normal (20% wt/wt; NP) or low (9% wt/wt; LP) protein diet during gestation and postnatal life. Offspring were examined at postnatal day 30. Protein restriction retarded growth of the kidney, liver, spleen, heart, and brain. All organs except the brain weighed less in female than male offspring. Protein restriction increased normalized (to body weight) brain weight, with females having relatively heavier brains than males. The effects of protein restriction were not sex dependent, except that normalized liver weight was reduced in males but increased in females. Glomerular volume, but not number, was greater in female than in male mice. Maternal protein restriction reduced nephron endowment similarly in male and female mice. Renal expression of AT1A receptor mRNA was approximately sixfold greater in female than male NP mice, but similar in male LP and female LP mice. We conclude that maternal protein restriction reduces nephron endowment in mice. This effect provides a basis for future studies of developmental programming in the mouse.

Obesity epidemic in India: intrauterine origins?

The epidemic of ‘obesity’ in India is not appreciated because BMI underestimates the adiposity of Indians. Specific adiposity measurements are necessary for recognition of the adiposity of ‘thin’ Indians. The origin of this adiposity is only beginning to be understood. In addition to a possible genetic predisposition, intrauterine ‘programming’ might be responsible, although in the ‘thrifty phenotype’ hypothesis the adiposity of the ‘thin’ fetus has not been appreciated. Dutch men who faced ‘winter hunger’ during the first trimester of their in utero life have become more obese as adults. Low birth weight predicts central obesity in some studies, including studies in urban children. It has also been shown that small and thin Indian newborns (weight 2·7?kg and ponderal index 2·4?kg\m3) have poor muscle and visceral mass but higher adiposity for a given weight compared with white Caucasian babies. This body composition is influenced by maternal adiposity before pregnancy and by aspects of maternal nutritional intake and circulating nutrient concentrations during pregnancy. There are no strong paternal determinants of adiposity at birth. Adiposity may be an integral part of the orchestrated adjustments made to support ‘brain preservation’ during intrauterine growth, because brain tissue is predominantly fat. Increased nutrition in the face of a genetic predisposition or multigenerational undernutrition increases maternal insulin resistance in late pregnancy and promotes fetal adiposity even in absence of marked hyperglycaemia. Further research is necessary to define the role of specific nutrients and metabolites in the intrauterine processes promoting adiposity before maternal interventions to curtail the epidemic of obesity and diabetes are planned.

Total body protein in healthy adolescent girls: validation of estimates derived from simpler measures with neutron activation analysis

BACKGROUND

Little recent and accurate information about body protein content in healthy adolescent girls is available.

OBJECTIVE

The objective was to assess the total body nitrogen (TBN) and total body protein (TBPr) contents of fat-free mass (P:FFM) in a group of healthy adolescent girls and to validate previously published TBN prediction equations.

DESIGN

TBN was measured with in vivo neutron activation analysis (TBNNAA). Bone mineral density and FFM were measured with dual-energy X-ray absorptiometry (FFMDXA), total body water and FFM were measured with bioimpedance analysis, and FFM was assessed by measuring skinfold thicknesses in 51 girls with a mean (+/- SD) age of 14.7 +/- 0.7 y. The validity of the TBN prediction equations was assessed with Bland-Altman analysis.

RESULTS

TBNNAA in our adolescent group was higher (1.49 kg) than values reported in earlier studies of women (1.25 and 1.31 kg), and P:FFM was slightly higher (23%) than that documented in adults (19-21%). Previously published TBN equations showed either systematic bias or wide limits of agreement.

CONCLUSION

A predictive equation derived from the present study population based on FFMDXA improves the prediction of TBN for groups of young girls but may not be helpful for individuals in clinical settings.

Causes of Intrauterine Growth Restriction and the Postnatal Development of the Metabolic Syndrome

The term intrauterine growth restriction (IUGR) is assigned to newborns with a birth weight and/or birth length below the 10th percentile for their gestational age and whose abdominal circumference is below the 2.5th percentile with pathologic restriction of fetal growth. IUGR is usually due to maternal, fetal, or placental factors. However, many IUGR cases have unknown underlying cause. Recent studies focus on new factors that can influence fetal development and birth outcome like the timing and the type of fetal nutrition, maternal psychosocial stress and personality variables, 11beta-hydroxysteroid dehydrogenase type 2 placental activity, the activity of the neuroendocrine system that mediates the effects of psychosocial stress, and the role of proinflammatory cytokines and of oxidative stress. Data have shown that IUGR is associated with a late life increased prevalence of metabolic syndrome, a condition associating obesity with hypertension, type 2 diabetes mellitus (DM2), and cardiovascular disease. Recent data demonstrated that the diabetes-associated mortality appears to be disproportionately concentrated among individuals of abnormal birth weight.

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.

Permanent reduction in heart and kidney organ growth in offspring of undernourished rat dams

OBJECTIVE

Maternal undernutrition affects fetal growth and development. We investigated whether maternal food restriction during pregnancy and/or lactation permanently alters organ growth among adult offspring.

STUDY DESIGN

From 10 days to term gestation and through 21 days lactation, control pregnant rats received ad libitum food, whereas study rats were 50% food restricted. Cross-fostering techniques were used to examine the effects of food restriction during pregnancy and/or lactation periods. Organs were dissected and weighed (percentage of body weight) at ages 3 weeks and 9 months.

RESULTS

Food restriction during pregnancy produced growth-restricted newborns that exhibited catch-up growth that resulted in markedly heavier adult offspring, although with relatively decreased weights of heart, kidney, lung, and brain as compared with controls. Conversely, food restriction during pregnancy/lactation or lactation alone resulted in adult offspring with similar body weights as controls, but with relatively decreased growth of heart and kidney. Males exhibited relatively smaller livers, whereas the females showed relatively smaller adrenal glands.

CONCLUSION

Sex-dependent, selective, and permanent changes in relative growth of heart and kidney may increase risk of adult diseases.

Potassium supplementation in kwashiorkor

BACKGROUND

Kwashiorkor is an edimatous form of severe malnutrition and is the predominant form of childhood malnutrition in Malawi. Potassium depletion is common and contributes to the high mortality. The aim of this study was to determine if high potassium supplementation improves the outcome of kwashiorkor treatment.

METHODS

We performed a randomised, double-blind, placebo-controlled, clinical trial of high potassium supplementation in 99 children with kwashiorkor. Controls (n = 51) received a standard potassium intake of 4.7 mmol/kg/day. The intervention group (n = 48) received 7.7 mmol/kg/day. All cases (intervention and control groups) were treated in the hospital-based Nutrition Rehabilitation Center and received a standard treatment regime of mild feeds, mineral and vitamin supplements, and antibiotics.

RESULTS

There was no significant difference in length of hospitalization, or time for resolution of oedema between groups. The case-fatality rate was reduced by 33% in the high potassium intervention group (13/48) compared to controls (21/51). There was a significant reduction in late deaths (13 in controls vs 3 in intervention group; odds ratio 5.3, 95% confidence interval 1.2-31.0) but no difference in early deaths (0-5 days). The intervention group also had significantly fewer presumed septic episodes (3 vs 18, odds ratio 8.9, confidence interval 2.2-50.9), respiratory symptoms, and new skin ulcerations than controls.

CONCLUSIONS

The high potassium supplementation reduced mortality and significant morbidity in kwashiorkor. This may be due to improved myocardial and immune function from earlier repletion of intracellular potassium. We recommend that the standard potassium supplement for the initial phase of treatment of kwashiorkor be increased from 4 to 8 mmol/kg/day.

Organ-selective growth in the offspring of protein-restricted mothers

Recent epidemiological studies in people whose birth weights were recorded many years ago suggest links between impaired growth during early life and the development of diseases, including diabetes, much later in life. The long-term effects of retarded early growth are proposed to result from malnutrition at critical periods of fetal or infant development leading to reduction in the growth of organs and permanent changes in their metabolism or structure, or both. In order to investigate this, a rat model was established which involved feeding either a diet containing 200 g protein/kg or an isoenergetic diet containing 80 g protein/kg to pregnant and lactating rats. In addition, cross-fostering techniques were employed which allowed a separate evaluation of the prenatal or the postnatal periods. The offspring were studied at 21 d of age or were weaned onto a normal laboratory chow and studied at 11 months of age. The 80 g protein/kg diet during pregnancy did not affect the overall reproductive although more subtle differences were evident. Permanent growth retardation was evident in offspring subjected to maternal protein restriction during the postnatal period. At 21 d of age the offspring of protein-restricted mothers exhibited selective changes in organ growth: compared with the body weight, the lung and brain experienced a smaller decrease in weight: the heart, kidney and thymus decreased proportionately: whereas, the pancreas, spleen, muscle and liver showed a greater reduction in weight. In older animals the muscle weight was lower in the male rats and the relative weight of pancreas was increased in the female rats.

The effect of starvation on leucine, alanine and glucose metabolism in obese subjects

The relationship between changes in ketone concentrations and leucine metabolism (seven obese subjects), glucose and alanine metabolism (seven obese subjects) was investigated using radioisotopic techniques after 12 h, 60 h and 2 weeks starvation. Leucine metabolism was also measured in five lean subjects after 12 h and 60 h starvation. In the obese subjects leucine concentration increased after 60 h starvation and leucine metabolic clearance rate, glucose and alanine concentration decreased (P < 0.05). Glucose and alanine production rate (Ra) decreased after 2 weeks (P < 0.05) but there was no change in leucine Ra after 60 h or 2 weeks. In the lean subjects leucine concentration, production rate and oxidation rate were increased after 60 h (P < 0.005, P < 0.05, P < 0.05). Ketone concentration was inversely related to alanine Ra (r = -0.51, P < 0.02) but was not related to measurements of protein metabolism in the obese subjects. This study demonstrates that the effect of short-term starvation on protein metabolism differs in lean and obese subjects. The decrease in glucose Ra during long-term starvation may be in part due to a decreased supply of alanine for gluconeogenesis.

A total body nitrogen facility for paediatric use

The design, calibration and evaluation of a facility for in vivo prompt gamma neutron capture analysis of total body nitrogen in children is described. The patient is scanned in both supine and prone positions, across a vertically collimated beam from a 1 GBq 252Cf fission source. Two NaI(T1) detectors are placed on either side of the patient, perpendicular to both the neutron beam and the scanning direction. The effective dose equivalent delivered to a child during an 840 s scan is approximately 0.14 mSv (QF = 10). Correction factors for nitrogen background (width-dependent), hydrogen background (1-4% of hydrogen gamma ray peak) and the differential attenuation of nitrogen and hydrogen gamma rays (width-dependent) can be applied to the measured nitrogen-to-hydrogen gamma ray counts ratio. By using the mass of hydrogen (based on body mass and fat mass) as an internal standard, the nitrogen mass can then be determined. Measurements with a urea-containing box phantom show that the current precision (CV) of the net nitrogen counts and of the nitrogen-to-hydrogen counts ratio is +/- 2.0% and +/- 1.5%, respectively. Using small anthropomorphic and other phantoms, estimation of the mass of nitrogen has a precision of +/- 1.4 to 5.4% and an accuracy of 97.1 to 101.5%.

The composition of body tissues (II). Fetus to young adult

The composition of body tissues is a function of the age, nutrition, state of health and physical activity of the individual. In this paper, the effects of age on the composition of healthy tissues are reviewed. Eleven soft tissues (adipose tissue, blood--whole, brain--whole, heart, kidney, liver, lung, muscle--skeletal, placenta, skin and spleen) and cortical bone are considered. Elemental compositions, mass and electron densities are tabulated for the tissues, as a function of age, from fetus to young adult. Although the compositions given here are predominantly for healthy tissues, reported changes because of dietary influences are briefly discussed.

The physiology of nutritional assessment and therapy in protein-calorie malnutrition

Protein-calorie malnutrition (PCM), in the purest sense, is the result of depleted body protein stores due to semistarvation. A review of the hormonal response to simple semistarvation illustrates the elegant adaptive ability of the body to respond to an inadequate diet. By contrast, the body's metabolic response to an injury or illness stimulus is a dynamic process orchestrated by monokines and hormones. Although the injury response, strictly speaking, is not synonymous with PCM, the resultant increased energy expenditure, anorexia, and potential for skeletal muscle breakdown can result in an even more rapid depletion of body protein stores. Ultimately, the need for nutritional support depends on the amount of recent weight loss, anticipated time of insufficient oral intake, and the degree of stress. A discussion of basic concepts of anthropometry precedes examples of advantages and disadvantages of a given anthropometric parameter for selected disease states. The effects of PCM on visceral structure and function are discussed in detail so that the reader can appreciate why the metabolic response to injury may have a very different impact on the nourished compared with the malnourished patient. Particular attention is paid to the adverse effects of PCM on immune function and its antithesis, the beneficial impact of nutritional repletion on the immune system. An approach to refeeding discusses indications for initiation of nutritional support, choice of route, design of a macronutrient and micronutrient regimen, and guidelines for monitoring. Familiarity with the metabolic alterations of refeeding is key to the mitigation of potentially life-threatening complications of sudden refeeding. Appreciation of the anticipated response to nutrition is important, as the response will vary with the degree of stress. A nearly optimal response can be expected with appropriate nutrition in the nonstressed semistarved patient, whereas inefficient repletion is to be expected in the severely stressed patient. The review concludes with a discussion of the role of nutrition as a modifier of the body's metabolic response to injury.

Erythrocyte membrane (Ca2+ + Mg2+)-ATPase in human protein-energy malnutrition

Calmodulin-free ghost membranes were prepared from erythrocytes of kwashiorkor children and from healthy children in the same age bracket. In the absence of calmodulin, the specific activity of Mg2+-dependent Ca2+-pumping ATPase (Ca2+ + Mg2+-ATPase) of kwashiorkor membranes was more than 40 percent lower than the specific activity of the normal enzymes, whose maximum velocity was increased by at least four-fold by the modulator protein. In contrast, the maximum velocity of the enzymes of kwashiorkor membranes was enhanced by calmodulin by about 1 1/2 times the basal activity of the normal enzymes and by 2 times the basal activity of the kwashiorkor enzymes. The affinity of the pump for ATP was lower in the membranes of kwashiorkor children (Km for ATP = 30.6 +/- 2.8 microM ATP) in comparison to normal membranes (Km for ATP = 21.7 +/- 2.0 microM ATP). Similarly, calmodulin-affinity of the enzymes, was lower in kwashiorkor membranes than in the normal membranes irrespective of source of calmodulin. Calmodulin from haemolysates of kwashiorkor red cells activated the enzymes of normal and kwashiorkor membranes to the same degree as calmodulin partially purified from the haemolysate of healthy children. A determination of the dependence of the activity of the pump on calcium in the absence and presence of calmodulin reveals that the affinity of the kwashiorkor enzymes for Ca2+ is at least 70 percent lower than that of enzymes of normal membranes. Altogether, these findings suggest that the Ca2+-pumping ATPase of kwashiorkor membranes is less functional than the enzymes of healthy erythrocytes.

Metabolic adaptation in protein-energy malnutrition

The metabolic response to chronic undernutrition covers a wide spectrum that ranges from decreased growth velocity in mild cases to profound distortion of body silhouette and composition and functional derangements in advanced stages of the protein-energy malnutrition-infection complex. A wide gamut of molecular, enzymatic, and hormonal processes assure a temporary availability of endogenous nutrients and the maintenance of vital functions.

Nutritional status--a prognostic indicator in head and neck cancer

A prospective study into the nutritional status of 114 patients with untreated primary squamous cell carcinoma of the head and neck was undertaken to assess its possible prognostic value for survival. Nutritional status was evaluated by anthropometry, creatinine height index estimation, serum albumin and transferrin assays, and nitrogen balance studies. Weight change and other anthropometric indices found to be the most reliable nutritional parameters were averaged to derive a clinically useful, general nutritional status score. A nutritional deficit was found in 43 of the 114 patients (37.7%) and was associated with neoplasms of the upper gastrointestinal tract in more than 80% of the patients. Life table analysis showed a statistically very highly significant difference between the survival of the adequately nourished patients (57.5% at 2 years) and the survival of the undernourished patients (7.5% at 2 years) (chi 2 = 36.08; P = .0). These results indicate that nutritional deficiency is an important adverse prognostic factor in head and neck cancer. Undernutrition probably exerts its effect, at least in part, by causing secondary immunologic dysfunction.

Variations of rat skull bone robusticity evoked by malnutrition

Weanling Holtzman rats of both sexes were fed a control (25% protein), a 10% protein, and a 2% protein semisynthetic diet. Protein deficit (PD) and protein calorie malnutrition (PCM) were estimated from comparisons between control and 10% protein, and control and 2% protein-fed animals, respectively. Animals were killed when they were 56 days old and their skulls cleaned and disarticulated. Individual bones and incisors were ovendried to constant weight. Total weight (TW), maximal projected length (MPL), and robusticity index (RI) were determined on each bone and incisor. It was found that all the bones and incisors did not behave uniformly. They followed two main patterns: (1) Proportional variation. RI values were not affected by nutritional deficiencies. All basicranial bones and 4 of 10 facial bones followed this pattern. (2) Non-proportional variation. RI values were affected by nutritional deficiencies. This pattern was subdivided into two trends: (2a) PD-diminished RI values. Both upper and lower incisors and 1 of 10 facial bones followed this trend. (2b) PCM, but not PD, decreased RI values. All vault bones and the remaining five facial bones followed this trend. It was concluded that there was a differential robusticity response among cranial base, calvaria, and incisors. This response may be connected with the differences in both histogenetic characteristics of those components and the functional roles they have to perform. The nonvault intramembranous bones showed a nonspecific behavior. This fact precluded the classification of the facial region in some of the previously defined patterns.

Fasting: the history, pathophysiology and complications

An appreciation of the physiology of fasting is essential to the understanding of therapeutic dietary interventions and the effect of food deprivation in various diseases. The practice of prolonged fasting for political or religious purposes is increasing, and a physician is likely to encounter such circumstances. Early in fasting weight loss is rapid, averaging 0.9 kg per day during the first week and slowing to 0.3 kg per day by the third week; early rapid weight loss is primarily due to negative sodium balance. Metabolically, early fasting is characterized by a high rate of gluconeogenesis with amino acids as the primary substrates. As fasting continues, progressive ketosis develops due to the mobilization and oxidation of fatty acids. As ketone levels rise they replace glucose as the primary energy source in the central nervous system, thereby decreasing the need for gluconeogenesis and sparing protein catabolism. Several hormonal changes occur during fasting, including a fall in insulin and T(3) levels and a rise in glucagon and reverse T(3) levels. Most studies of fasting have used obese persons and results may not always apply to lean persons. Medical complications seen in fasting include gout and urate nephrolithiasis, postural hypotension and cardiac arrhythmias.

Insulin to inhibit protein catabolism after injury

Using patients with varying degrees of trauma as their own controls we compared three isocaloric regimens in three-day crossover studies; 9.4 g of nitrogen as l-amino acids was also given daily. The urea production rate was used as an index of protein breakdown. We found that in catabolic patients, insulin and glucose produced a strikingly greater inhibition of protein breakdown that glucose alone, and that glucose alone was marginally more protein sparing than a regimen containing mainly fat (intralipid and sorbitol). These differences were not seen in noncatabolic patients (urea production rate less than 15 g daily). In the catabolic patients (urea production rate greater than 15 g daily) the protein-sparing effect of insulin was proportional to the initial urea production rate. We therefore concluded that insulin has important protein-sparing effects in severely ill traumatized patients, but little effect when there is no increased catabolic rate.

Metabolic and nutritional factors in children with renal insufficiency

Uremia is associated with a decrease in muscle and adipose tissue mass and a low weight-for-height ratio. These findings are related to dietary deficiencies in uremia--particularly energy deficiency and to metabolic disorders characteristic of uremia. These latter have features of an exaggerated catabolic state which may be modified by other stresses, e.g. short starvation or high-protein diets. Recommendations for diet therapy for children with uremia are of limited value because of the lack of definitive studies. At present, diet should be adequate in energy to improve nitrogen balance and weight gain commensurate with age. There may be advantages to using a protein:energy ratio in the diet that is lower than the ratio used in conventional diets.

Fasting metabolism in infants. I. Effect of severe undernutrition on energy and protein utilization

Fasting energy metabolism was studied in infants to determine the rates of utilization of endogenous carbohydrate, fat, and protein in relation to length of fasting, glucose homeostasis, other circulating energy substrates and hormones, and severe depletion of energy reserves due to prior malnutrition. Five subjects about 1 yr of age were each studied before and after restoration of their energy reserves. Following 3 days of a standard maintenance intake of energy and protein, the subjects were fasted until glycogen oxidation became negligible. Total energy utilization, determined by hourly oxygen consumption, did not diminish as a result of fasting but was significantly less when malnourished than when recovered, 66 versus 79 kcal/kg/day. In all cases the major energy source shifted from oxidation of dietary carbohydrate and glycogen to oxidation of fat, determined from the respiratory quotient, until the oxidation of glycogen became negligible and fat provided 94% of energy in the malnourished subjects after 21 hr and 92% in the recovered subjects after 27 hr. Utilization of protein, determined from urinary nitrogen excretion, remained very low in the malnourished infants accounting for a maximum of 4% of energy, 103 mg N/kg/day, whereas after recovery, protein utilization doubled as a result of fasting, finally accounting for 7% of energy, 226 mg N/kg/day (p less than 0.005). Urea accounted for 60% of total urinary N in both groups and plasma urea increased correspondingly in the recovered but not in the malnourished subjects. Plasma glucose decreased to about 40 mg/100 ml in both groups as glycogen oxidation diminished. The maximum amount of glucose that could have been derived from dietary carbohydrate, glycogen, glycerol, and amino acids decreased over this time from about 6 to 1 mg/kg/min. Alanine declined in relation to glucose concentration and was not different in the two groups in spite of the difference in urea production. Glycerol free fatty acids, beta-hydroxybutyrate, and acetoacetate increased in both groups, but the latter three of these remained significantly less in the malnourished group. Insulin decreased rapidly and remained equally low in both groups. Urinary epinephrine increased in both groups and cortisol was elevated after fasting, while growth hormone did not increase significantly. It is concluded that fasting infants complete the transition from dietary carbohydrate to endogenous fat as the major energy source much faster than do adults, proportionate to relatively greater energy utilization. Severe wasting did not prevent energy homeostasis in spite of greatly depleted body fat. Oxidation of fat continued to provide virtually all of the fasting energy requirements, although ketosis was relatively less. Utilization of endogenous protein also increased as a result of fasting but, by contrast, provided only a very small fraction of total energy, and this was substantially diminished as a result of wasting, similar to what has been found in starved adults...

Body fat and adipose tissue cellularity in infants: a longitudinal study

Body fat, fat cell size, and fat cell number were determined in a longitudinal study on 16 normal-weight infants during the age period 1-18 mo. The methods used included whole-body counting of 40K for determination of body fat and adipose tissue biopsies. A new method of calculation of body fat in infants is presented. No sex differences were found. Body fat expressed as per cent of body weight increased from 16.2% to 28.1%. From 1 to 12 mo of age the expansion of body fat was explained by and increase in fat cell size, while in the age period 12-18 mo it was mainly due to an increase in fat cell number. At 18 mo lthe fat cell size was the same as in 8-yr-old girls and 22-yr-old women (normal-weight females previously studied). The fat cell number at 18 mo, however, was far below the number at 8 yr of age, as well as the still higher number of the 22-yr-old women.

Delayed nerve conduction velocities in children with protein-calorie malnutrition

Protein-calorie malnutrition in human beings and animals affects the myelination and growth of the nervous system. The effects of PCM on the developing nervous system were evaluated by measuring the nerve conduction velocities in 93 (38 marasmus, 13 kwashiorkor, and 42 control) children in ulnar, median, peroneal, and posterior tibial nerves. The children were divided into three age groups: Group I, six to 12 months; Group II, 13 to 24 months; Group III, 25 to 48 months. All 13 children with kwashiorkor demonstrated irritability, delayed milestones, and muscular wasting; and six also had hypoactive muscle reflexes. Conduction velocities were reduced in each type of malnutrition, with statistically significant differences in the three groups of marasmic children and in Group III kwashiorkor children. Children with kwashiorkor in Group II had significantly reduced velocities only in the nerves of the lower extremities. These data suggest PCM, when it occurs during the development of the nervous system, affects myelination of the peripheral nerves.