Plasma concentrations of transsulfuration pathway products during nasoenteral and intravenous hyperalimentation of malnourished patients

Evidence and Perspectives for Choline Supplementation during Parenteral Nutrition-A Narrative Review

Choline is an essential nutrient, with high requirements during fetal and postnatal growth. Tissue concentrations of total choline are tightly regulated, requiring an increase in its pool size proportional to growth. Phosphatidylcholine and sphingomyelin, containing a choline headgroup, are constitutive membrane phospholipids, accounting for >85% of total choline, indicating that choline requirements are particularly high during growth. Daily phosphatidylcholine secretion via bile for lipid digestion and very low-density lipoproteins for plasma transport of arachidonic and docosahexaenoic acid to other organs exceed 50% of its hepatic pool. Moreover, phosphatidylcholine is required for converting pro-apoptotic ceramides to sphingomyelin, while choline is the source of betaine as a methyl donor for creatine synthesis, DNA methylation/repair and kidney function. Interrupted choline supply, as during current total parenteral nutrition (TPN), causes a rapid drop in plasma choline concentration and accumulating deficit. The American Society for Parenteral and Enteral Nutrition (A.S.P.E.N.) defined choline as critical to all infants requiring TPN, claiming its inclusion in parenteral feeding regimes. We performed a systematic literature search in Pubmed with the terms "choline" and "parenteral nutrition", resulting in 47 relevant publications. Their results, together with cross-references, are discussed. While studies on parenteral choline administration in neonates and older children are lacking, preclinical and observational studies, as well as small randomized controlled trials in adults, suggest choline deficiency as a major contributor to acute and chronic TPN-associated liver disease, and the safety and efficacy of parenteral choline administration for its prevention. Hence, we call for choline formulations suitable to be added to TPN solutions and clinical trials to study their efficacy, particularly in growing children including preterm infants.

Bile acid-farnesoid X receptor-fibroblast growth factor 19 axis in patients with short bowel syndrome: The randomized, glepaglutide phase 2 trial

BACKGROUND

The gut-liver axis and enterohepatic circulation have gained increasing attention lately. Patients with short bowel syndrome (SBS) are, in fact, human knock-out models that may assist in the understanding of bile acid synthesis and regulation. We evaluated effect of glepaglutide (a long-acting glucagon-like peptide-2 analog) on bile acid synthesis (the enterohepatic circulation of bile acids and liver biochemistry in patients with SBS).

METHOD

In a single-center, double-blinded, dose-finding, crossover phase 2 trial, 18 patients with SBS were randomly assigned to 2 of 3 treatment arms (0.1, 1, and 10 mg) with daily subcutaneous injections of glepaglutide for 3 weeks. The washout period between the 2 treatment periods was 4-8 weeks. Measurements were performed at baseline and at the end of each treatment period and included postprandial plasma samples for fibroblast growth factor 19 (FGF19), 7α-hydroxy-4-cholesten-3-one (C4), total excretion of fecal bile acids, gene expression of farnesoid X receptor (FXR) in intestinal mucosal biopsies, total plasma bile acids, and liver biochemistry.

RESULTS

Compared with baseline, the median (interquartile range) postprandial response (area under the curve 0-2h) of FGF19 increased by 150 h × ng/L (41, 195; P = 0.001) and C4 decreased by 82 h × µg/L (-169, -28; p = 0.010) in the 10-mg dose. FXR gene expression did not change in any of the groups. Alkaline phosphatase significantly decreased.

CONCLUSION

Glepaglutide may stimulate the bile acid/FXR/FGF19 axis, leading to increased plasma concentrations of FGF19. Thereby, glepaglutide may ameliorate the accelerated de novo bile acid synthesis and play a role in the prevention and/or treatment of intestinal failure-associated liver disease.

Review of parenteral nutrition-associated liver disease

Parenteral nutrition has been widely used in patients whose gastrointestinal tract is anatomically or physiologically unavailable for sufficient food intake. It has been considered lifesaving but is not without adverse effects. It has been proven to cause liver injury through different mechanisms. We present a review of parenteral nutrition-associated liver disease.

Impaired bile acid metabolism with defectives of mitochondrial-tRNA taurine modification and bile acid taurine conjugation in the taurine depleted cats

Taurine that conjugates with bile acid (BA) and mitochondrial-tRNA (mt-tRNA) is a conditional essential amino acid in humans, similarly to cats. To better understand the influence of acquired depletion of taurine on BA metabolism, the profiling of BAs and its intermediates, BA metabolism-enzyme expression, and taurine modified mt-tRNAs were evaluated in the taurine deficient diet-supplemented cats. In the taurine depleted cats, taurine-conjugated bile acids in bile and taurine-modified mt-tRNA in liver were significantly decreased, whereas unconjugated BA in serum was markedly increased. Impaired bile acid metabolism in the liver was induced accompanied with the decreases of mitochondrial cholesterol 27-hydroxylase expression and mitochondrial activity. Consequently, total bile acid concentration in bile was significantly decreased by the low activity of mitochondrial bile acid synthesis. These results implied that the insufficient dietary taurine intake causes impaired bile acid metabolism, and in turn, a risk for the various diseases similar to the mitochondrial diseases would be enhanced.

Choline and DHA in Maternal and Infant Nutrition: Synergistic Implications in Brain and Eye Health

The aim of this review is to highlight current insights into the roles of choline and docosahexaenoic acid (DHA) in maternal and infant nutrition, with special emphasis on dietary recommendations, gaps in dietary intake, and synergistic implications of both nutrients in infant brain and eye development. Adequate choline and DHA intakes are not being met by the vast majority of US adults, and even more so by women of child-bearing age. Choline and DHA play a significant role in infant brain and eye development, with inadequate intakes leading to visual and neurocognitive deficits. Emerging findings illustrate synergistic interactions between choline and DHA, indicating that insufficient intakes of one or both could have lifelong deleterious impacts on both maternal and infant health.

Choline Protects Against Intestinal Failure-Associated Liver Disease in Parenteral Nutrition-Fed Immature Rats

BACKGROUND

Deficiency of choline, a required nutrient, is related to intestinal failure-associated liver disease (IFALD). Therefore, we aimed to investigate the effects of choline supplementation on IFALD and the underlying mechanisms.

METHODS

Male Sprague-Dawley rats (4 weeks old) were fed AIN-93G chow and administered intravenous 0.9% saline (control), parenteral nutrition (PN), or PN plus intravenous choline (600 mg/kg) for 7 days. We evaluated body weight, hepatic histology, biochemical indicators, triglycerides, oxidative status, methylation levels of peroxisomal proliferator-activated receptor alpha (PPARα) gene promoter, expression of PPARα and carnitine palmitoyltransferase 1 (CPT1), and levels of choline metabolites.

RESULTS

The PN + choline group exhibited improved body weight compared with the PN group. PN impaired hepatic function, increased hepatic triglycerides, induced dyslipidemia, enhanced reactive oxygen species and malondialdehyde, and reduced total antioxidant capacity. The PN group had higher pathologic scores than the control group. These results were prevented by choline administration. Compared with the control group, PN increased PPARα promoter methylation and hepatic betaine concentration, reduced hepatic choline and phosphatidylcholine (PC) levels, decreased plasma choline and betaine concentrations, and downregulated PPARα and CPT1 mRNA and protein expression. Choline supplementation elevated hepatic choline and PC levels and enhanced plasma choline, betaine, and PC concentrations but reduced hepatic betaine level, reversed PPARα promoter hypermethylation, and upregulated PPARα and CPT1 mRNA and protein expression in PN-fed rats, compared with rats receiving PN alone.

CONCLUSION

Choline addition to PN may prevent IFALD by reducing oxidative stress, enhancing hepatic fat export, and promoting fatty acid catabolism in immature rats receiving PN.

Liver Disease in Patients on Total Parenteral Nutrition

Parenteral nutrition-associated liver disease (PNALD) spectrum ranges from liver enzyme abnormalities to steatosis to fibrosis, and, eventually, cirrhosis from total parenteral nutrition (TPN). The pathophysiology is postulated to be multifactorial. Diagnosis in adults is primarily by exclusion, eliminating other causes of chronic liver disease or cirrhosis, and other factors seen in critically ill or postoperative patients on TPN. Principal treatment is avoiding TPN. If this is not feasible, research supports fish oil-based lipid emulsions in TPN formulations to reduce risk and progression of PNALD. With liver and intestinal failure, liver and intestine transplant is an option.

Choline Deficiency Is Associated With Increased Risk for Venous Catheter Thrombosis

BACKGROUND

Patients with intestinal failure who require long-term parenteral nutrition (PN) develop catheter thrombosis as a complication. This patient group may also develop choline deficiency because of a defect in the hepatic transsulfuration pathway in the setting of malabsorption. This study was undertaken to determine whether choline deficiency is a risk factor for development of catheter thrombosis.

METHODS

Plasma free and phospholipid-bound choline concentrations were measured in a group of 41 patients that required long-term PN. Episodes of catheter thrombosis from onset of PN to the time of blood testing were recorded.

RESULTS

Sixteen (39%) patients developed catheter thrombosis, and 5 of these had recurrent catheter thrombosis. Plasma free choline was 7.7 +/- 2.7 nmol/mL in patients with no history of catheter thrombosis and 6.2 +/- 1.7 nmol/mL in patients with previous catheter thrombosis (p = .076 by Wilcoxon rank-sum test). The partial correlation between plasma free choline concentration and the frequency of clots after controlling for catheter duration was r = -0.33 (p = .038). The relative risk for catheter thrombosis in subjects with a plasma free choline concentration <8 nmol/mL was 10.0, 95% confidence interval (1.134-88.167). Plasma phospholipid-bound choline concentration was 2191.7 +/- 679.0 nmol/mL in patients with previous catheter thrombosis and 2103.3 +/- 531.2 nmol/mL in patients without history of catheter thrombosis (p = NS).

CONCLUSION

Choline deficiency is a significant risk factor for development of catheter thrombosis in patients with intestinal failure who require PN.

Pathogenesis and treatment of parenteral nutrition-associated liver disease

BACKGROUND

Parenteral nutrition-associated liver disease (PNALD) has been common in patients who require long-term parenteral nutrition. PNALD develops in 40%-60% of infants on long-term parenteral nutrition compared with 15%-40% of adults on home parenteral nutrition for intestinal failure. The pathogenesis of PNALD is multifactorial and remains unclear. There is no specific treatment. Management strategies for its prevention and treatment depend on an understanding of many risk factors. This review aims to provide an update on the pathogenesis and treatment of this disease.

DATA SOURCES

A literature search was performed on the MEDLINE and Web of Science databases for articles published up to October 2011, using the keywords: parenteral nutrition associated liver disease, intestinal failure associated liver disease, lipid emulsions and fish oil. The available data reported in the relevant literatures were analyzed.

RESULTS

The literature search provided a huge amount of evidence about the pathogenesis and management strategies on PNALD. Currently, lack of enteral feeding, extended duration of parenteral nutrition, recurrent sepsis, and nutrient deficiency or excess may play important roles in the pathogenesis of PNALD. Recent studies found that phytosterols, present as contaminants in soy-based lipid emulsions, are also an important factor in the pathogenesis. Moreover, the treatment of PNALD is discussed.

CONCLUSIONS

The use of lipid emulsions, phytosterols in particular, is associated with PNALD. Management strategies for the prevention and treatment of PNALD include consideration of early enteral feeding, the use of specialized lipid emulsions such as fish oil emulsions, and isolated small bowel or combined liver and small bowel transplantation. A greater understanding of the pathogenesis of PNALD has led to promising interventions to prevent and treat this condition. Future work should aim to better understand the mechanisms of PNALD and the long-term outcomes of its treatment.

A brief history of choline

In 1850, Theodore Gobley, working in Paris, described a substance, 'lecithine', which he named after the Greek 'lekithos' for egg yolk. Adolph Strecker noted in 1862 that when lecithin from bile was heated, it generated a new nitrogenous chemical that he named 'choline'. Three years later, Oscar Liebreich identified a new substance, 'neurine', in the brain. After a period of confusion, neurine and choline were found to be the same molecule, and the name choline was adapted. Lecithin was eventually characterized chemically as being phosphatidylcholine. In 1954, Eugene Kennedy described the cytidine 5-dihphosphocholine pathway by which choline is incorporated into phosphatidylcholine. A second route, the phosphatidylethanolamine-N-methyltransferase pathway, was identified by Jon Bremer and David Greenberg in 1960. The role of choline as part of the neurotransmitter acetylcholine was established by Otto Loewi and Henry Dale. Working in the 1930s at the University of Toronto, Charles Best showed that choline prevented fatty liver in dogs and rats. The importance of choline as an essential nutrient for human health was determined in the 1990s through controlled feeding studies in humans. Recently, an understanding of the role of genetic variation in setting the dietary requirement for choline in people is being unraveled.

Two patients with hepatic mtDNA depletion syndromes and marked elevations of S-adenosylmethionine and methionine

This paper reports studies of two patients proven by a variety of studies to have mitochondrial depletion syndromes due to mutations in either their MPV17 or DGUOK genes. Each was initially investigated metabolically because of plasma methionine concentrations as high as 15-21-fold above the upper limit of the reference range, then found also to have plasma levels of S-adenosylmethionine (AdoMet) 4.4-8.6-fold above the upper limit of the reference range. Assays of S-adenosylhomocysteine, total homocysteine, cystathionine, sarcosine, and other relevant metabolites and studies of their gene encoding glycine N-methyltransferase produced evidence suggesting they had none of the known causes of elevated methionine with or without elevated AdoMet. Patient 1 grew slowly and intermittently, but was cognitively normal. At age 7 years he was found to have hepatocellular carcinoma, underwent a liver transplant and died of progressive liver and renal failure at age almost 9 years. Patient 2 had a clinical course typical of DGUOK deficiency and died at age 8 ½ months. Although each patient had liver abnormalities, evidence is presented that such abnormalities are very unlikely to explain their elevations of AdoMet or the extent of their hypermethioninemias. A working hypothesis is presented suggesting that with mitochondrial depletion the normal usage of AdoMet by mitochondria is impaired, AdoMet accumulates in the cytoplasm of affected cells poor in glycine N-methyltransferase activity, the accumulated AdoMet causes methionine to accumulate by inhibiting activity of methionine adenosyltransferase II, and that both AdoMet and methionine consequently leak abnormally into the plasma.

Appropriate protein and specific amino acid delivery can improve patient outcome: fact or fantasy?

Protein utilization and requirements in critical illness are much researched and debated topics. The enhanced turnover and catabolism of protein in the setting of critical illness is well described and multifactorial in nature. The need to preserve lean body mass and enhance nitrogen retention in this state to improve immunologic function and reduce morbidity is well described. Debates as to the optimum amount of protein to provide in such states still exist, and a significant amount of research has contributed to our understanding of not only how much protein to supply to these patients, but how best to do so. Small peptide formulations, intact protein formulations, branched chain amino acids, and specialty formulas all exist, and their benefits, drawbacks, and potential uses have been investigated. Specific amino acid therapy has become part of the concept of immunonutrition, or the modification and enhancement of the immune response with specific nutrients. In this article, we describe the changes in outcomes demonstrated through the provision of protein, both as a macronutrient and as specific amino acids.

Oral choline supplementation in children with intestinal failure

Choline deficiency leads to steatohepatitis, elevated transaminases, susceptibility to septic shock, and an increased risk of central catheter thrombosis. Children with intestinal failure (IF) are at risk for choline deficiency. In an unblinded, open-label study, we studied 7 children with IF on parenteral nutrition, measured their plasma free choline level, and, if low, supplemented enterally with adequate intake (AI) doses of choline. Four to 6 weeks later we remeasured their plasma free choline. Unlike adults, infants did not respond to oral choline supplementation at AI doses. Additionally, we have calculated plasma free choline percentiles versus age for normal children.

Abnormal liver function tests in the parenteral nutrition fed patient

Liver dysfunction is common in individuals receiving parenteral nutrition (PN) and particularly in neonates and infants. Abnormalities of liver function tests in patients receiving short term PN are usually transient but in individuals receiving long term PN, substantial liver damage and ultimately end stage liver disease may occur. The aetiology is complex, involving a large number of patient related and nutrition related factors. The terminology intestinal failure associated liver disease (IFALD) is therefore more appropriate than PN associated liver disease. Effort should be made to prevent liver dysfunction by managing sepsis, avoiding parenteral overfeeding, employing cyclical parenteral feeding and encouraging enteral nutrition where possible. Intake of soybean based parenteral lipid emulsions should be reduced in individuals with established IFALD, possibly to be replaced by lipid emulsions containing medium chain triacylglycerol, monounsaturated fatty acids or fish oil although larger clinical studies are needed. Similarly, evidence supporting the widespread use of parenteral choline and taurine supplementation in the prevention or treatment of IFALD remains limited. There are more data to support the use of oral antibiotics to treat bacterial overgrowth and oral ursodeoxycholic acid in neonates. Ultimately, severe IFALD may necessitate referral for small intestine and/or liver transplantation.

Plasma Amino Acid Concentrations in 108 Children Receiving a Pediatric Amino Acid Formulation as Part of Parenteral Nutrition

BACKGROUND

Plasma amino acid (PAA) levels can be largely normalized during parenteral nutrition (PN) in infants and children using a pediatric-specific amino acid (AA) formulation. However, these previous results were based on individual clinical studies of small populations of neonates and infants.

OBJECTIVE

We have now examined AA levels in 108 children (0–7 years of age) receiving a pediatric-specific AA formulation in PN using a single analytical methodology.

METHODS

Infants and children were enrolled in specific protocols and parents/caregivers gave informed consent. Patients were stable and receiving age-appropriate intakes of AA and non-protein calories. Samples were obtained between 8 and10 am, processed immediately, deproteinized, and AA concentrations (μmol/L) were determined on a Beckman 6300 analyzer. Means and SD were calculated for sub-populations stratified by age: 0–1 month (48 patients, n=139), 1–6 months (36 patients, n=124), 7–12 months (11 patients, n=41), and 1–7 years (13 patients, n=51). Z scores were calculated for each amino acid [(observed mean - normal control mean)/normal control SD].

RESULTS

When compared to the neonatal reference range, nonessential AA had Z scores that ranged from −1.84 (asparagine) to +1.48 (threonine). Only plasma free cystine, free tyrosine, and phenylalanine had Z scores outside the −2.0 to +2.0 range (95% confidence limits). Plasma free cystine values were low in all groups except neonates. Free tyrosine levels were low in all groups despite the presence of N-acetyl-L-tyrosine in the pediatric AA formulation. Phenylalanine levels were elevated only in neonates. When children 1 to 7 years old were compared with an age-matched reference range, plasma free cystine values were low (Z score −2.47), as were plasma glutamine values (−3.11), but elevations were found in the dicarboxylic amino acids aspartic acid (+2.5) and glutamic acid (+4.27). Regardless of reference range used for comparison, all essential amino acids, except phenylalanine in neonates, were within range (−2 to +2 of the 95% confidence limits).

CONCLUSIONS

While most AAs were within the normal range, formulation modifications are needed to normalize free cystine in infants and young children, free tyrosine in all children, and phenylalanine in neonates. The decrease in glutamine concentrations in older children has been noted by our group before, and may imply limited ability to convert glutamic acid to glutamine, or increased consumption of glutamine. In either case, increased concentrations of glutamine in older children, especially those receiving home parenteral nutrition, should be considered.

Whole-blood-free choline and choline metabolites in infants who require chronic parenteral nutrition therapy

BACKGROUND AND AIM

Choline deficiency is associated with hepatic dysfunction. Parenteral nutrition (PN) and lipid emulsions contain phosphatidylcholine (PtdCho) but insignificant free choline (FCho). PtdCho is sequentially degraded to glycerolphosphocholine (GPCho), phosphocholine (PCho), and finally to FCho. Biosynthesis of FCho may be insufficient during PN therapy. The aim of the study was to examine the status of FCho and related metabolites in infants on prolonged (> or =4 weeks) PN.

METHODS

Whole blood concentrations of FCho, PtdCho, GPCho, and PCho were measured and compared in infants on PN and infants on enteral feeds (controls).

RESULTS

Infants on PN (n = 14) had higher birth weight but same postnatal age as controls (n = 14) (mean +/- standard deviation) 8.3 +/- 3.9 versus 7.4 +/- 3.6 weeks. Parenteral nutrition was associated with increased PtdCho 1761 +/- 452 versus 1471 +/- 221 nmol/mL, P = 0.04. Mean whole blood FCho, GPCho, and PCho concentrations did not differ significantly in PN versus controls: 40.0 +/- 15.4 versus 50.8 +/- 49.7, 16.4 +/- 14.5 versus 25.2 +/- 29.3, and 15.3 +/- 13.5 versus 22.0 +/- 14.8 nmol/mL, respectively. However, PCho was positively correlated with GPCho in controls (r = 0.91, P < 0.01) but not PN (r = 0.24, P = NS), and infants receiving >90% of daily energy intake from PN (n = 6) had decreased PCho, 5.7 +/- 4.1 nmol/mL, compared with those receiving <90% of daily energy intake (n = 8) 22.5 +/- 13.7 nmol/mL, P < 0.05, and controls, 22.0 +/- 14.8 nmol/mL, P < 0.01.

CONCLUSIONS

Decreased whole-blood concentrations of choline suggest possible evidence of choline deficiency as illustrated by decreased whole-blood PCho. Choline supplementation should be investigated in infants who require prolonged PN, and whole-blood PCho can be used to monitor response.

Nutritional deficiencies in intestinal failure

Intestinal failure (IF) is the ultimate malabsorption state, with multiple causes, requiring long-term therapy with enteral or intravenous fluids and nutrient supplements. The primary goal during management of children with potentially reversible IF is to promote intestinal autonomy while supporting normal growth, nutrient status, and preventing complications from parenteral nutrition therapy. This article presents how an improved understanding of digestive pathophysiology is essential for diagnosis, successful management, and prevention of nutrient deficiencies in children with IF.

Chronic biochemical cholestasis in patients receiving home parenteral nutrition: prevalence and predisposing factors

BACKGROUND

Chronic biochemical cholestasis has been shown to be associated with a fivefold increase in histologically advanced liver disease in patients receiving home parenteral nutrition.

AIMS

To investigate prevalence of chronic biochemical cholestasis in home parenteral nutrition patients and examine factors influencing its occurrence.

METHODS

Records of all patients receiving home parenteral nutrition for >6 months treated at a single centre were reviewed and plasma biochemistry recorded. Logistic regression analysis was employed to identify factors associated with prevalence of chronic biochemical cholestasis.

RESULTS

Records of 113 patients were reviewed. The point prevalence of chronic biochemical cholestasis was 24%, increasing to 28% if patients receiving parenteral fluid and electrolytes only were excluded. In multivariate analysis, presence of colon in continuity was associated with a significantly lower prevalence of chronic biochemical cholestasis, while total parenteral calorie intake was associated with a higher prevalence of chronic biochemical cholestasis. No association was seen between small intestinal lengths or between parenteral lipid intake and chronic biochemical cholestasis in multivariate analysis.

CONCLUSIONS

Chronic biochemical cholestasis is common in patients receiving home parenteral nutrition. High parenteral calorie intake and lack of a colon in continuity with small intestine are independently associated with an increased risk of chronic biochemical cholestasis.

The essentiality of sulfur is closely related to nitrogen metabolism: a clue to hyperhomocysteinaemia

N and S metabolisms are closely interwoven throughout both the plant and animal kingdoms. The essentiality of S relates to its participation in the structure of S-containing amino acids (SAA), to its inclusion in many sulfonated molecules, and to a myriad of metabolic and catalytic reactions of vital importance. Methionine (Met) is the indispensable SAA supplied by food proteins and its plasma homeostasis is achieved via a number of highly efficient regulatory mechanisms. In all conditions characterised by a negative body protein balance such as in dietary restriction or cytokine-induced hypercatabolic losses, N and S endogenous pools manifest parallel tissue depletion rates. Adaptive conservation of N and S body stores is reached by a functional restraint of the trans-sulfuration cascade, through the depression of cystathionine β-synthase activity. As a result, upstream accumulation of homocysteine favours its re-methylation conversion to Met which helps maintain metabolic pathways of survival value. In addition to the measurement of vitamin indices, that of plasma transthyretin, a sensitive marker of protein nutritional status, is proposed to identify the fluctuations of the total body N component accountable for the alterations of homocysteine concentrations in body fluids.

Managing liver dysfunction in parenteral nutrition

Parenteral nutrition is life saving in patients with intestinal failure but liver dysfunction is commonly encountered, especially in neonates. Although abnormal liver function tests associated with short-term parenteral nutrition are usually benign and transient, liver dysfunction in both children and adults receiving long-term parenteral nutrition can progress to end-stage liver disease and liver failure. The aetiology of parenteral nutrition-associated liver disease is complex and multifactorial, with a range of patient, disease and nutrition-related factors implicated. Sepsis is of particular importance, as is the lack of enteral nutrition and overfeeding with intravenous glucose and/or lipid. Deficiencies of a number of amino acids including choline and taurine have also been implicated. Management of hepatic dysfunction in parenteral nutrition should initially focus on preventing its occurrence. Sepsis should be managed appropriately, enteral nutrition should be encouraged and maximised where possible and parenteral overfeeding should be avoided. Provision of parenteral lipid should be optimised to prevent the adverse effects of both deficiency and excess, and cyclical rather than continuous parenteral feeding should be administered. There is some evidence of benefit in neonates from oral antibiotics to prevent intestinal bacterial overgrowth and from oral ursodeoxycholic acid, but less to support their use in adults. Similarly, data to support widespread use of parenteral choline or taurine supplementation are lacking at present. Ultimately, severe parenteral nutrition-associated liver disease may necessitate referral for small intestine and/or liver transplantation.

Parenteral nutrition-associated liver disease in adult and pediatric patients

There are essentially 3 types of hepatobiliary disorders associated with parenteral nutrition (PN) therapy: steatosis, cholestasis, and gallbladder sludge/stones. Reported prevalence rates of PN-associated liver disease (PNALD) vary greatly, and there are distinct differences between adult and pediatric patients. Various etiologic factors have been evaluated for significance in contributing to PNALD, including enteral feeding history, septic events, bacterial overgrowth, length of intestinal resection, and prematurity/low birth weight. Etiologic factors specifically related to the PN formulation or nutrient intake have also been evaluated, including excessive calorie intake, dextrose-to-lipid ratio, amino acid dose, taurine deficiency, IV fat emulsion (IVFE) dose, carnitine deficiency, choline deficiency, and continuous vs cyclic infusion. Minor increases in serum aminotransferase concentrations are relatively common in patients receiving PN therapy and generally require no intervention. The primary indicator of cholestasis is a serum conjugated bilirubin >2 mg/dL. When a patient receiving PN develops liver complications, it is necessary to rule out all treatable causes and minimize other risk factors. All potential hepatotoxic medications and herbal supplements should be eliminated. Modifications to the PN regimen that may be helpful include reduction of calories, reduction of IVFE dose to <1 g/kg/d, supplementation of taurine in the infant, and use of cyclic infusion. Initiation of even small amounts of enteral nutrition and use of ursodiol may be beneficial in stimulating bile flow. In the long-term PN patient with severe and progressive liver disease, intestinal or liver transplantation may be the only remaining treatment option.

Total Parenteral Nutrition: Challenges and Practice in the Cirrhotic Patient

Patients with cirrhosis develop metabolic derangements of protein, carbohydrate, and lipid metabolism. Malnutrition is commonplace and is associated with morbidity and mortality. Specific nutrient deficiencies may occur and enteral or parenteral nutritional support may improve outcome in appropriately selected patients. Parenteral nutrition itself has been associated with hepatic dysfunction, although the preponderance of evidence suggests that hepatic dysfunction is more a function of the underlying disorder and malabsorption. Intravenously infused organic nutrients may be metabolized differently than the same nutrient consumed enterally. The pathophysiology of total parenteral nutrition-associated liver disease is discussed as well as potential management options.

Parenteral nutrition-associated liver disease and the role for isolated intestine and intestine/liver transplantation

Parenteral nutrition-associated liver disease (PNALD) is the most devastating complication of long-term parenteral nutrition therapy. Because its progression is typically insidious and its long-term consequences are generally underappreciated, PNALD is often recognized too late, when liver injury is irreversible. When end-stage liver disease (ESLD) develops in these patients, most potential interventions are futile and transplantation of both an intestine and a liver becomes the only viable option, despite the relatively poor outcomes associated with this combined procedure. Although likely multifactorial in origin, the etiology of PNALD is poorly understood. Early clinical intervention with a combination of nutritional, medical, hormonal, and surgical therapies can be effective in preventing liver disease progression. If these interventions fail, intestinal transplantation should be performed expeditiously before development of ESLD mandates simultaneous inclusion of a liver graft as well.

Choline deficiency causes reversible hepatic abnormalities in patients receiving parenteral nutrition: proof of a human choline requirement: a placebo-controlled trial

BACKGROUND

Previous studies have shown that plasma free choline concentrations are significantly decreased in many long-term home total parenteral nutrition (TPN) patients. Furthermore, low choline status has been associated with both hepatic morphologic and hepatic aminotransferase abnormalities. A preliminary pilot study suggested choline-supplemented TPN may be useful in reversal of these hepatic abnormalities.

METHODS

Fifteen patients (10 M, 5 F) who had required TPN for > or =80% of their nutritional needs were randomized to receive their usual TPN (n = 8), or TPN to which 2 g choline chloride had been added (n = 7) for 24 weeks. Baseline demographic data were similar between groups. Patients had CT scans of the liver and spleen, and blood for plasma free and phospholipid-bound choline, alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase, gamma glutamyl transferase (GGT), bilirubin, serum lipids, complete blood count (CBC), and chemistry profile obtained at baseline, and weeks 2, 4, 6, 12, 16, 20, 24, and 34. CT scans were analyzed for Hounsfield unit (HU) densities.

RESULTS

There were no significant differences in any measured parameters after 2 weeks. However, at 4 weeks, a significant difference in liver HU between groups was observed (13.3+/-5.0 HU [choline] vs 5.8+/-5.2 HU [placebo], p = .04). This significant trend continued through week 24. Recurrent hepatic steatosis and decreased HU were observed at week 34, 10 weeks after choline supplementation had been discontinued. A significant increase in the liver-spleen differential HU was also observed in the choline group (10.6+/-6.2 HU [choline] vs 1.3+/-3.3 HU [placebo], p = .01). Serum ALT decreased significantly (p = .01 to .05) in the choline group vs placebo at weeks 6,12, 20, and 24. Serum AST was significantly decreased in the choline group by week 24 (p = .02). The serum alkaline phosphatase was significantly reduced in the choline group at weeks 2, 12, 20, 24, and 34 (p = .02 to 0.07). Total bilirubin was normal in these patients and remained unchanged during the study. Serum GGT tended to decrease more in the choline group, but the greater decrease was not statistically significant.

CONCLUSIONS

Choline deficiency is a significant contributor to the development of TPN-associated liver disease. The data suggest choline is a required nutrient for long-term home TPN patients.

Carnitine-deficient myopathy as a presentation of tyrosinemia type I

Carnitine deficiency secondary to renal Fanconi's tubulopathy has been described in only a few inborn errors of metabolism: cystinosis, galactosemia, and Fanconi-Bieckel syndrome. We report a 27-month-old infant who presented with a sudden change in gait owing to proximal muscle weakness. The laboratory evaluation showed carnitine deficiency associated with Fanconi's tubulopathy. Eventually, tyrosinemia type I was diagnosed. Carnitine deficiency can contribute to the clinical picture of hepatorenal tyrosinemia and should therefore be evaluated and treated.

Cysteine metabolism and whole blood glutathione synthesis in septic pediatric patients

OBJECTIVE

To investigate whole body in vivo cysteine kinetics and its relationship to whole blood glutathione (GSH) synthesis rates in septic, critically ill pediatric patients and controls.

DESIGN

Prospective cohort study.

SETTING

Multidisciplinary intensive care unit and pediatric inpatient units at a children's hospital.

PATIENTS

Ten septic pediatric patients and ten controls (children admitted to the hospital for elective surgery).

INTERVENTIONS

Septic patients (age, 31 months to 17 yrs) and controls (age, 24 months to 21 yrs) received a 6-hr primed, constant, intravenous tracer infusion of l-[1-13C]cysteine. Blood samples were obtained to determine isotopic enrichment of plasma cysteine and whole blood [1-13C]cysteinyl-glutathione by gas-chromatography mass spectrometric techniques. The plasma flux and oxidation rate of cysteine and the fractional and absolute synthesis rates of GSH were determined. Septic patients received variable protein and energy intake, as per routine clinical management, and controls were studied in the early postabsorptive state.

MEASUREMENTS AND MAIN RESULTS

Plasma cysteine fluxes were increased in the septic patients when compared with the controls (68.2 +/- 17.5 [sd] vs. 48.7 +/- 8.8 micromol x kg(-1) x hr(-1); p <.01), and the fraction of plasma cysteine flux associated with oxidative disposal was similar among the groups. The absolute rates of GSH synthesis in whole blood were decreased (p <.01) in the septic patients (368 +/- 156 vs. 909 +/- 272 micromol x L(-1) x day(-1)). The concentration of whole blood GSH also was decreased in the septic group (665.4 +/- 194 vs. 1059 +/- 334 microM; p <.01)

CONCLUSIONS

Whole blood glutathione synthesis rates are decreased, by about 60%, in critically ill septic children receiving limited nutritional support. Plasma cysteine fluxes and concentration of cysteine were increased in the septic patients, suggesting a hypermetabolic state with increased protein breakdown. The mechanisms whereby GSH synthesis rates are decreased in these patients are probably multifactorial, presumably involving an inflammatory response in the presence of limited nutritional support. The role of nutritional modulation and the use of cysteine prodrugs in maintaining GSH concentration and synthesis remain to be established.

Verbal and visual memory improve after choline supplementation in long-term total parenteral nutrition: a pilot study

BACKGROUND

Previous investigations have demonstrated that choline deficiency, manifested in low plasma-free choline concentration and hepatic injury, may develop in patients who require long-term total parenteral nutrition (TPN). Preliminary studies have suggested lecithin or choline supplementation might lead to improved visual memory in the elderly and reverse abnormal neuropsychological development in children. We sought to determine if choline-supplemented TPN would lead to improvement in neuropsychological test scores in a group of adult, choline-deficient outpatients receiving TPN.

METHODS

Eleven subjects (8 males, 3 females) who received nightly TPN for more than 80% of their nutritional needs for at least 12 weeks before entry in the study were enrolled. Exclusion criteria included active drug abuse, mental retardation, cerebral vascular accident, head trauma, hemodialysis or peritoneal dialysis, (prothrombin time [PT] >2x control), or acquired immune deficiency syndrome (AIDS). Patients were randomly assigned to receive their usual TPN regimen (n = 6, aged 34.0 +/- 12.6 years) over a 12-hour nightly infusion or their usual TPN regimen plus choline chloride (2 g) (n = 5, aged 37.3 +/- 7.3 years). The following neuropsychological tests were administered at baseline and after 24 weeks of choline supplementation (or placebo): Weschler Adult Intelligence Scale-Revised (WAIS-R, intellectual functioning), Weschler Memory Scale-Revised (WMS-R, two subtests, verbal and visual memory), Rey-Osterrieth Complex Figure Test (visuospatial functioning and perceptual organization), Controlled Oral Word Association Test (verbal fluency), Grooved Pegboard (manual dexterity and motor speed), California Verbal Learning Test (CVLT, rote verbal learning ability), and Trail Making Parts A & B (visual scanning, psychomotor speed and set shifting). Scores were reported in terms of standard scores including z scores and percentile ranks. Mean absolute changes in raw scores were compared between groups using the Wilcoxon rank sum test, where p values < .05 constituted statistical significance.

RESULTS

Significant improvements were found in the delayed visual recall of the WMS-R (7.0 +/- 2.7 vs -.33 +/- 5.7, p = .028), and borderline improvements in the List B subset of the CVLT (1.0 +/- 0.8 vs -2.0 +/- 2.4, p = .06) and the Trails A test (-3.8 +/- 8.1 vs 3.7 +/- 4.5 seconds, p = .067). No other statistically significant changes were seen.

CONCLUSIONS

This pilot study indicates both verbal and visual memory may be impaired in patients who require long-term TPN and both may be improved with choline supplementation.

Plasma choline concentrations in children requiring long-term home parenteral nutrition: a case control study

BACKGROUND

Low plasma free choline concentration has been associated with elevated serum hepatic aminotransferase concentrations and hepatic steatosis in adults who need home parenteral nutrition (HPN). We sought to determine if plasma free choline is similarly reduced in children who need home total parenteral nutrition (TPN).

METHODS

We compared the plasma free choline concentration in 21 children who required long-term HPN with 31 normal controls. Patients had received HPN for 75 +/- 13 (SD) months (range 3-206 months). All control children ingested a normal, mixed, nonvegetarian diet.

RESULTS

The mean plasma free choline concentration in the children receiving HPN was significantly lower than normal children (6.6 +/- 4.3 vs 8.0 +/- 2.3 nmol/mL, p = .002). Plasma free choline concentration was correlated with age (r = -0.43, p = .049). Using multiple linear regression analysis for age, sex, and squared age (considered in order to account for possible nonlinearity between choline and age), HPN children showed a steady and significant decline in plasma free choline concentration with increased age at the rate of 0.03 nmol/mL per month. Plasma lipid bound choline concentration did not vary with age. No relationship was seen between either plasma free and lipid bound choline concentration and amount of daily IV lipid infusion. A significant negative correlation was observed between plasma free choline concentration and aspartate aminotransferase (AST) and alanine aminostransferase (ALT) (r = -0.72, p = .04 and r = -0.80, p = .02, respectively).

CONCLUSION

Our data support the notion that patients who need long-term HPN without significant enteral feeding have a significant risk for the development of choline deficiency with its associated hepatic dysfunction.

S-adenosylmethionine deficiency and TNF-alpha in lipopolysaccharide-induced hepatic injury

S-adenosylmethionine (Adomet) is a substrate for de novo synthesis of choline. Adomet deficiency occurs in certain types of liver injury, and the injury is attenuated by exogenous Adomet. Tumor necrosis factor-alpha (TNF-alpha) is also a mediator of these models of hepatotoxicity. We investigated the role of Adomet in lipopolysaccharide (LPS)-induced liver injury in rats made deficient in both Adomet and choline. Rats were maintained on either a methionine-restricted and choline-deficient (MCD) diet or a diet containing sufficient amounts of all nutrients [methionine and choline sufficient (MCS)] and then administered either LPS or saline. MCS-LPS rats had normal liver histology and no change in serum transaminases compared with the MCS-saline control group. MCD-saline rats had hepatosteatosis but no necrosis, and a five- to sevenfold increase in transaminases vs. the MCS-saline group. MCD-LPS rats additionally had hepatonecrosis and a 30- to 50-fold increase in transaminases. Exogenous Adomet administration to MCD-LPS rats corrected the hepatic deficiency of Adomet but not of choline, prevented necrosis but not steatosis, and attenuated transaminases. Serum TNF-alpha was sixfold higher in MCD rats even without LPS challenge and 300-fold higher with LPS challenge. Exogenous Adomet attenuated increased serum TNF-alpha in MCD-LPS rats.

Essential nature of choline with implications for total parenteral nutrition

Choline is known to be important in many metabolic pathways; at this time, however, it is not considered an essential nutrient for human beings. Current evidence strongly suggests that choline is "conditionally essential," particularly for patients receiving total parenteral nutrition (TPN). Studies in patients receiving long-term TPN have shown that low levels of plasma choline are common and can be associated with hepatic steatosis. Treatment of these patients with oral administration of choline improved plasma levels and decreased hepatic fat content; however, oral choline supplements are associated with poor compliance. More recently, investigators have evaluated intravenous administration of choline as a treatment for TPN-associated hepatic steatosis in patients with documented subnormal plasma free-choline levels. Initial results indicate that intravenous administration of choline may be an effective treatment for TPN-associated hepatic dysfunction.

Carnitine metabolism in chronic liver disease

The liver is a central organ for carnitine metabolism and for the distribution of carnitine to the body. It is therefore not surprising that carnitine metabolism is impaired in patients and experimental animals with certain types of chronic liver disease. In this review, the changes in carnitine metabolism associated with chronic liver disease and the role of carnitine as a therapeutic agent in some of these conditions are discussed.

Amino acid and energy needs of pediatric patients receiving parenteral nutrition

The technique of parenteral nutrition has become such an established part of modern pediatric care that it is difficult to imagine how pediatricians, as recently as 25 years ago, managed a large group of very difficult patients; however, despite its obvious nutritional advantages, the technique is not without problems. Many of these can be circumvented or controlled by careful attention to all aspects of the technique. Certainly the incidence of these problems can be maintained at a level sufficiently low that the benefits of the technique far outweigh its risks; however, the technique clearly can be further improved. One requirement for doing so is to recognize that the technique is deceptively simple and that it should not be used indiscriminantly without careful consideration of indications and alternative strategies for nutritional management. Additional research also is required. As discussed earlier, the available parenteral amino acid mixtures and lipid emulsions, although considerably improved over earlier versions, remain far from optimal. Some of the actual and theoretic problems that should be addressed in the near future are discussed in the preceding sections; there also are many others.

The depression of hepatic drug conjugation reactions in rats after lipid-free total parenteral nutrition administered via the portal vein

BACKGROUND

Total parenteral nutrition provides nutrition support in patients who are unable to eat. Long-term parenteral nutrition is accompanied by alterations in gut and liver function including changes in drug metabolism. This study examined the effects of lipid-free total parenteral nutrition in rats on (1) the overall elimination pharmacokinetics of acetaminophen, (2) changes in sulfation and glucuronidation pathways during acetaminophen elimination, and (3) hepatic drug metabolizing enzyme activities determined in vitro.

METHODS

Chronic indwelling catheters were implanted in the aorta, inferior vena cava, and portal vein of adult male Sprague-Dawley rats. Total parenteral nutrition, consisting of 25% dextrose, 5% amino acids, electrolytes, and vitamins, was infused via the portal vein for up to 14 days. Acetaminophen pharmacokinetics were characterized in vivo and selected drug metabolizing enzyme activities were determined in vitro.

RESULTS

Parenteral nutrition for 10 days decreased the total clearance of acetaminophen by 23% (from 11.5 +/- 1.4 to 8.9 +/- 1.4 mL/min per kg; p < .05) and decreased the formation clearance to acetaminophen sulfate (from 6.2 +/- 0.4 to 3.9 +/- 0.5 mL/min per kg; p < .05). Parenteral nutrition decreased microsomal cytochrome P450 concentration (47%), p-nitroanisole demethylase activity (68%) and p-nitrophenol UDP-glucuronosyltransferase activity (58%). Cytosolic glutathione-S-transferase activity towards 1-chloro-2,4-dinitrobenzene decreased 29%. Sulfotransferase activity towards p-nitrophenol and acetaminophen was decreased 48% and 25%, respectively.

CONCLUSION

Lipid-free, total parenteral nutrition depresses drug conjugative metabolism in rats. The magnitude of this effect in humans remains to be investigated.

Oral S-adenosyl-L-methionine (SAMe) administration enhances bile salt conjugation with taurine in patients with liver cirrhosis

We investigated whether the oral administration of SAMe influences the hepatic availability of sulphur amino acids and the extent of bile salt amidation with taurine in liver cirrhosis. Ten patients with cirrhosis (eight Child-Pugh A and 2 B, aged 48-65 years), were studied before and 2 months after oral SAMe administration (800 mg per day). Bile was obtained using a string-test device (Entero-test), after gall-bladder contraction with caerulein. No significant changes were found in the per cent composition of biliary amino acids, except for an increase in glutamic acid (from 3.7 +/- 0.6% before to 6.1 +/- 1.1% after SAMe, p = 0.003) and taurine from 2.2 +/- 2.3% (range 0.4-6.8) to 7.2 +/- 9.2% (range 0.5-28.1), (NS). HPLC analysis showed a trend towards increased per cent tauroconjugation of all individual bile salts, with a significant rise in taurochenodeoxycholic acid (from 15.0 +/- 9.4% to 25.3 +/- 9.7%, p = 0.05) and a drop in glycocholic acid (from 39.1 +/- 15.3% to 25.3 +/- 9.8%, p = 0.05). These data suggest that in the cirrhotic liver exogenous SAMe is partially metabolized to taurine, which is used for bile salt amidation.

Abnormal metabolism of S-adenosyl-L-methionine in hypoxic rat liver. Similarities to its abnormal metabolism in alcoholic cirrhosis

S-Adenosylmethionine (AdoMet) is an important biologic methylating agent for nucleic acids, phospholipids, biologic amines, and proteins. Previous studies indicated that hepatic AdoMet synthetase and hepatic levels of AdoMet are subnormal in patients with alcoholic cirrhosis. This abnormality limits the patients' capacity to convert phosphatidylethanolamine to phosphatidylcholine by way of phosphatidylethanolamine-N-methyltransferase (PEMT). Because alcoholic consumption appears to be associated with hepatic hypoxia, we previously measured AdoMet concentration in liver cells under acute hypoxia and found the level to be decreased substantially. In the present study, we determined whether a similar metabolic abnormality was also observed in rats maintained under physiologic hypoxia for 9 days and administered standard rat chow. The study showed that AdoMet levels in hypoxic rat (ave +/- SD) were significantly lower than those in the control (36.8 +/- 11.6 vs. 60.4 +/- 2.3 nmol/g liver; P < 0.05). Also significantly lower in the hypoxic group were the activities of AdoMet synthetase (0.60. +/- 0.07 vs. 0.97 +/- 0.20 U; P < 0.05) and PEMT (26.2 +/- 4.2 vs. 35.6 +/- 5.8 U; P < 0.02). The mRNA levels of AdoMet synthetase also declined in hypoxia indicating that hypoxia may modulate the gene expression of hepatic AdoMet synthetase. Thus, in vivo hypoxia may have an important effect on 1-carbon metabolism.

The effect of ethanol on one-carbon metabolism: increased methionine catabolism and lipotrope methyl-group wastage

Deficiency of choline and methionine produces hepatic steatosis similar to that seen with ethanol, and supplementation with these lipotropes can prevent ethanol-induced fatty liver. These effects are thought to occur through alterations in membrane phospholipid metabolism, but the mechanism whereby this occurs and the precise nature of the changes brought about by ethanol in the interactions of choline and methionine metabolism remain unclear. Through the known effects on hepatic glutathione (which requires as a precursor a product of methionine catabolism), ethanol might affect hepatic one-carbon metabolism, which requires the participation of both methionine and choline in the transfer of methyl groups. This has been investigated with a radiorespirometric technique to assess the in vivo oxidation of the methyl groups of lipotropes and their intermediates in ethnaol- and control-fed rats. Enzyme activities of one-carbon transfer reactions and the hepatic levels of methionine and alpha-aminobutyrate, an end product of methionine catabolism, have been measured. The effect of ethanol feeding on hepatic S-adenosylmethionine and S-adenosylhomocysteine has also been assessed. Ethanol increases the oxidation to carbon dioxide of the methyl group of methionine by a factor of 2.9 (p = 0.002) and produces a 3.6-fold (p = 0.0001) accumulation of alpha-aminobutyrate, indicating a marked increase in methionine catabolism. Hepatic methionine levels are unchanged by ethanol, however, and this may be explained by a dramatic increase in the turnover of the methyl groups of choline and betaine in response to ethanol (times 3.6 and 4.2, respectively, p < 0.003), suggesting greatly increased use of the choline oxidation pathway to remethylate homocysteine through betaine homocysteine methyltransferase.(ABSTRACT TRUNCATED AT 250 WORDS)

Low plasma free choline is prevalent in patients receiving long term parenteral nutrition and is associated with hepatic aminotransferase abnormalities

Hepatic transaminase abnormalities have been previously reported in patients receiving long term total parenteral nutrition (PN). We sought to determine if such abnormalities are caused by choline deficiency-induced hepatocyte damage. In 41 subjects (19 male, 22 female) aged 45.1 +/- 24.3 years (range 0.1-79 years) who have received PN for 5.5 +/- 4.7 years (range 0.1-14.5 years). We determined plasma free and phospholipid bound choline levels, serum albumin, ALT and AST. We also determined the daily volume of intravenous lipid emulsion received by the patients as well as the concentration of free choline and phospholipid bound choline in the lipid emulsion. Plasma free choline was low in 33 41 subjects (mean 7.15 +/- 2.5 nmol/ml, range 3.3-15.6, normal 11.4 +/- 3.7). Phospholipid bound choline was normal in 34 41 subjects (mean 2157 +/- 620 nmol/ml, range 1026-3887, normal 2364 +/- 774). Elevations in ALT and AST were significantly correlated with plasma free choline (r = -0.34, p = 0.03, r = -0.37, p = 0.02 respectively) but not with phospholipid bound choline. No relationship was found between age, PN duration or daily volume of intravenous lipid and plasma free or phospholipid bound choline. The lipid emulsion contained 24 +/- 6 nmol/ml of free choline and 11 630 +/- 552 nmol/ml of phospholipid bound choline. We conclude that low plasma free choline is prevalent in patients receiving long term PN and this abnormality is associated with elevated serum aminotransferases. Furthermore, intravenous lipid emulsion is an inadequate source of choline for this patient group.

Choline: an important nutrient in brain development, liver function and carcinogenesis

Choline is required to make certain phospholipids which are essential components of all membranes. It is a precursor for biosynthesis of the neurotransmitter acetylcholine and also is an important source of labile methyl groups. Much attention has been given to the effect of supplemental choline upon brain function, i.e., enhancement of acetylcholine synthesis and release. In addition, choline supplements administered to rats in utero or shortly after birth permanently after brain function. The mechanisms for this effect is unknown and under investigation at this time. Healthy humans fed diets deficient in choline, and humans fed parenterally have decreased plasma choline concentrations and develop liver dysfunction that is similar to that seen in choline-deficient animals. In experimental animals, fatty liver occurs in choline deficiency because phosphatidylcholine synthesis is required for very low-density lipoprotein secretion. This accumulation of lipids in liver may explain why choline-deficient rats spontaneously develop hepatocarcinoma. We found that choline deficiency was associated with the accumulation of 1,2-diacylglycerol, an activator of protein kinase C. Several lines of evidence indicate that cancers might develop secondary to abnormalities in protein kinase C-mediated signal transduction.