Effects of intravenous fat infusion on neonatal neutrophil and platelet function

Impact of lipid emulsions in parenteral nutrition on platelets: a literature review

Lipid emulsions are essential components of parenteral nutrition solutions that provide energy and essential fatty acids. The complexity of the formulations of lipid emulsions may lead to adverse outcomes such as platelet reactivity and changes in platelet aggregation and related coagulation. Platelets are responsible for haemostasis; they activate and demonstrate morphological changes upon extracellular factors to maintain blood fluidity and vascular integrity. Although parenteral nutrition lipid emulsions are generally found safe with regard to modulation of platelet activity, studies are still accumulating. Thus, this review aims to investigate platelet-related changes by parenteral nutrition lipid emulsions in human studies. Studies have pointed out patients at risk of bleeding and increased platelet aggregation responses due to the administration of lipid emulsions. Lipid emulsions may further benefit patients at high risk of thrombosis due to anti-thrombotic effects and should be cautiously used in patients with thrombocytopenia. The reported platelet-related changes might be associated with the fatty acid change in the plasma membranes of platelets following changes in platelet synthesis and plasma levels of eicosanoids. In conclusion, studies investigating platelets and parenteral nutrition should be supported to minimize the adverse effects and to benefit from the potential protective effects of parenteral nutrition lipid emulsions.

REVIEW: Practical strategies to maintain anabolism by intravenous nutritional management in children with inborn metabolic diseases

One of the most vital elements of management for patients with inborn errors of intermediary metabolism is the promotion of anabolism, the state in which the body builds new components, and avoidance of catabolism, the state in which the body breaks down its own stores for energy. Anabolism is maintained through the provision of a sufficient supply of substrates for energy, as well as critical building blocks of essential amino acids, essential fatty acids, and vitamins for synthetic function and growth. Patients with metabolic diseases are at risk for decompensation during prolonged fasting, which often occurs during illnesses in which enteral intake is compromised. During these times, intravenous nutrition must be supplied to fully meet the specific nutritional needs of the patient. We detail our approach to intravenous management for metabolic patients and its underlying rationale. This generally entails a combination of intravenous glucose and lipid as well as early introduction of protein and essential vitamins. We exemplify the utility of our approach in case studies, as well as scenarios and specific disorders which require a more careful administration of nutritional substrates or a modification of macronutrient ratios.

Platelet functional and transcriptional changes induced by intralipid infusion

Multiple studies have shown the effects of long-term exposure to high-fat or western diets on the vascular system. There is limited knowledge on the acute effects of high circulating fat levels, specifically on platelets, which have a role in many processes, including thrombosis and inflammation. This study investigated the effects of acute, high-fat exposure on platelet function and transcript profile. Twenty healthy participants were given an intravenous infusion of 20% Intralipid emulsion and heparin over 6 hours. Blood samples were taken prior to and the day after infusion to measure platelet function and transcript expression levels. Platelet aggregation was not significantly affected by Intralipid infusion, but, when mitochondria function was inhibited by carbonyl cyanide 3-chlorophenylhydrazone (CCCP) or oligomycin, platelet aggregation was higher in the post-infusion state compared to baseline. Through RNA sequencing, and verified by RT-qPCR, 902 miRNAs and 617 mRNAs were affected by Intralipid infusion. MicroRNAs increased include miR-4259 and miR-346, while miR-517b and miR-517c are both decreased. Pathway analysis identified two clusters significantly enriched, including cell motility. In conclusion, acute exposure to high fat affects mitochondrial-dependent platelet function, as well as the transcript profile.

Intravenous lipids for preterm infants: a review

Extremely low birth weight infants (ELBW) are born at a time when the fetus is undergoing rapid intrauterine brain and body growth. Continuation of this growth in the first several weeks postnatally during the time these infants are on ventilator support and receiving critical care is often a challenge. These infants are usually highly stressed and at risk for catabolism. Parenteral nutrition is needed in these infants because most cannot meet the majority of their nutritional needs using the enteral route. Despite adoption of a more aggressive approach with amino acid infusions, there still appears to be a reluctance to use early intravenous lipids. This is based on several dogmas that suggest that lipid infusions may be associated with the development or exacerbation of lung disease, displace bilirubin from albumin, exacerbate sepsis, and cause CNS injury and thrombocytopena. Several recent reviews have focused on intravenous nutrition for premature neonate, but very little exists that provides a comprehensive review of intravenous lipid for very low birth and other critically ill neonates. Here, we would like to provide a brief basic overview, of lipid biochemistry and metabolism of lipids, especially as they pertain to the preterm infant, discuss the origin of some of the current clinical practices, and provide a review of the literature, that can be used as a basis for revising clinical care, and provide some clarity in this controversial area, where clinical care is often based more on tradition and dogma than science.

Relationship Between Triglyceride Tolerance, Body Mass Index, and Fat Depots in Hospitalized Patients Receiving Parenteral Nutrition

BACKGROUND

Hypertriglyceridemia has been associated with adverse outcomes in patients receiving intravenous fat emulsions (IVFEs), but little is known about its prevalence and causes.

MATERIALS AND METHODS

The study investigated whether a relationship exists between body mass index (BMI) and triglyceride tolerance in parenterally fed patients. We conducted a retrospective analysis of 287 adults receiving parenteral nutrition to determine whether patients with very low BMI (VLBMI, <16 kg/m(2)) tolerate IVFEs better than do patients with low BMI (LBMI, 16-18.4 kg/m(2)), normal-weight patients (NBMI, 18.5-24.9 kg/m(2)), and overweight/obese patients (HBMI, ≥25 kg/m(2)).

RESULTS

The median triglyceride concentration during IVFE was significantly lower in VLBMI patients at 107 mg/dL compared with 124 mg/dL in non-VLBMI patients (P = .016), despite higher lipid infusion rates in the VLBMI group. There was a significant association between triglycerides and BMI in the aggregate cohort (R = 0.2375, P < .0001), with the highest frequency of hypertriglyceridemia occurring in HBMI patients despite relatively lower lipid and energy supply. In a subset of VLBMI patients (n = 36) who had an abdominal computed tomography scan, there was 25- to 100-fold variability in the size of the abdominal adipose tissue depots. In this subgroup, triglyceride concentrations correlated with visceral fat but not subcutaneous abdominal fat.

CONCLUSIONS

In summary, patients with VLBMI have lower triglyceride concentrations during IVFEs than do other individuals, but there is considerable variability in triglycerides and body fat in this group. Caution should be employed with the use of IVFEs, especially in HBMI patients.

Dose of intravenous lipids and rate of bacterial clearance in preterm infants with blood stream infections

BACKGROUND

Intravenous lipid emulsion (IVLE) is an integral part of the total parenteral nutrition (TPN) regimen in neonates. The use of IVLE during sepsis is the subject of controversy because it may interfere with phagocytosis of microbes by macrophages and may lead to significant hypertriglyceridemia.

OBJECTIVE

This paper aims to study the rate of clearance of bacteria in relation to dose of IVLE administered to preterm infants with blood stream infections (BSIs).

METHODS

Preterm infants (mean gestational age ± SD, 32.0 ± 2.5 weeks) with culture-proven BSI and receiving TPN were randomized to two groups. The first group (n = 22) was given the usual dose of IVLE according to a standard protocol (starting from 0.5 g kg(-1) day(-1) and gradually increased by 1 g kg(-1) day(-1) to a maximum of 3.5 g kg(-1) day(-1)); in the second group (n = 20), IVLE were restricted at a dose of 1 g kg(-1) day(-1). Samples for blood cultures were withdrawn every 24 h until a negative culture was obtained. CRP was measured daily until its normalization. Serum triglycerides were monitored daily.

RESULTS

The rate of bacterial clearance was significantly more rapid in the restricted-dose IVLE group compared to the standard-dose group [72 (48-120) versus 144 (72-168) h, p = 0.001]. Daily weight increment was significantly greater in the standard-dose IVLE group compared to the restricted-dose IVLE group [25 (6.9-31.9) versus 0.9 (-3.3-11.7) g, p = 0.0001]. The duration of antibiotic use was significantly reduced in the restricted-dose IVLE group compared with the standard-dose IVLE group (10.0 ± 4.5 vs 14.9 ± 5.1 days; p = 0.003). The durations of TPN, mechanical ventilation, and hospitalization were not significantly different between groups.

CONCLUSIONS

Restriction of the dose of IVLE to 1 g kg(-1) day(-1) in preterm infants with BSI is associated with earlier negative blood cultures and reduced duration of antibiotic therapy but was associated with a lower daily weight increments.

Effect of different lipid emulsions on the immunological function in humans: a systematic review with meta-analysis

BACKGROUND & AIMS

Reports regarding the pro- or anti-inflammatory effects of lipid emulsion used in parenteral nutrition are conflicting. Aim was to assess the effect of different intravenous lipid emulsions on immunological function in humans.

METHODS

We performed a computerized bibliographic search, searched reference lists in trial reports, hand-searched journals and contacted experts in the field. Randomized clinical trials evaluating the immunological effects of different parenteral lipid emulsions were included. Three authors independently performed data extraction, statistical processes were performed by two experts. Immunological parameters were classified by two immunologists as marker of improved or worsened immune function. A meta-analysis with standardized effect size estimation was performed for the comparison between long-chain triglycerides vs. glucose or other fat emulsions.

RESULTS

Of 682 assessed studies, 120 compared the immunological effects of intravenously applied lipid emulsions. Of 30 randomized trials, 14 were included in the meta-analysis. None of the lipid regimens showed any clear effect on the evolution of the immunological status or mortality in humans. Length of hospital stay and stay in the intensive care unit could not be evaluated.

CONCLUSION

We found no evidence that lipid emulsions and in particular those containing long-chain triglycerides have an unfavorable effect on immune function.

Early introduction of lipids to parenterally-fed preterm infants

BACKGROUND

Lipids are essential components of parenteral nutrition for preterm infants. Parenteral lipids can be administered through a peripheral vein, and their early introduction offers the potential advantages of increasing energy intake and providing essential fatty acids and fat soluble vitamins. Concerns have been raised about potential adverse effects including chronic lung disease (CLD), increase in pulmonary vascular resistance, impaired pulmonary gas diffusion, bilirubin toxicity, sepsis and free radical stress.

OBJECTIVES

To determine the safety and efficacy of 'early' (</= 5 days after birth) introduction of lipids to parenterally fed preterm infants.

SEARCH STRATEGY

Eligible studies were identified by searching MEDLINE (December 2004), EMBASE 1980 - 2004, Oxford Database of Perinatal Trials, Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 4, 2004) and CINAHL (December 1982 - December 2004). Abstracts of the Society for Pediatric Research were hand searched from 1980 to 2004 inclusive. No language restrictions were applied.

SELECTION CRITERIA

All randomised or quasi randomised controlled trials comparing 'early' versus 'no early' introduction of lipids to preterm infants.

DATA COLLECTION AND ANALYSIS

Data were sought regarding effects on growth and risk of CLD or death, other respiratory morbidities including duration of respiratory support, duration of supplemental oxygen, the need for home oxygen, pneumothorax (PTX), pulmonary haemorrhage and pulmonary interstitial emphysema (PIE), >/= stage 2 necrotizing enterocolitis (NEC), retinopathy of prematurity (ROP), patent ductus arteriosus (PDA), sepsis, intraventricular haemorrhage (IVH), clinically significant thrombocytopenia and significant jaundice. Methodological quality of eligible studies was assessed according to allocation concealment, blinding of intervention, blinding of outcome assessment and completeness of follow up. When appropriate, meta-analysis was conducted to provide a pooled estimate of effect. For categorical data the Typical relative risk (RR), Typical risk difference (RD) and number needed to treat (NNT) with 95% confidence intervals (CI) were calculated. Continuous data were analysed using weighted mean difference (WMD).

MAIN RESULTS

Five studies (n = 397) were included in the review. All studies compared the effectiveness and safety of 'early' introduction versus 'no early' introduction of lipids in preterm infants. The timing of introduction of 'early lipids' ranged from < 12 hours after birth to day five of life. The timing of introduction of lipids in the 'no early' lipid group ranged from day six after birth to day 14 after birth. The initial dose ranged from 0.5 - 1 g/kg/day with gradual daily increments up to a maximum of 2.5 - 3.5 g/kg/day. For the primary outcomes (growth, death and CLD), there was no statistically significant difference between the 'early' lipid and 'no early' lipid groups. Days to regain birth weight: [WMD 0.59 (95% CI -2.41, 3.58); two trials; N = 71]. Rate of weight gain (g/day) during period of hospital stay: [MD -2.40 (95% CI -5.30, 0.50); one trial; N = 129]Death (irrespective of time): [Typical RR 1.04 (95% CI 0.69, 1.56); Typical RD 0.01 (95% CI -0.07, 0.08); five trials; N = 397]Neonatal deaths: [Typical RR 1.35 (95% CI 0.78, 2.34); Typical RD 0.05 (95% CI -0.04, 0.13); four trials; N = 268].CLD: [Typical RR 1.10 (95% CI 0.81, 1.49); Typical RD 0.04 (95% CI -0.09, 0.17); two trials; N = 193]. For the secondary outcomes of other respiratory morbidities including duration of respiratory support, duration of supplemental oxygen, PTX, pulmonary haemorrhage, PIE, NEC, ROP, PDA, sepsis, IVH and significant jaundice, there were no statistically significant differences between 'early' and 'no early' lipid groups.

AUTHORS' CONCLUSIONS

No statistically significant effects of 'early introduction' of lipids on short term nutritional or other clinical outcomes, either benefits or adverse effects, were demonstrated in the studies reviewed. Based on the currently available evidence, 'early' initiation of lipids (</= 5 days after birth) can not be recommended for short term growth or to prevent morbidity and mortality in preterm infants.

Evaluation of complications and prognostic factors associated with administration of total parenteral nutrition in cats: 75 cases (1994–2001)

OBJECTIVE

To determine frequency and types of complications, prognostic factors, and primary diseases affecting clinical outcome associated with administration of total parenteral nutrition (TPN) in cats.

DESIGN

Retrospective study.

ANIMALS

75 cats that received TPN for > or = 12 hours.

PROCEDURE

Medical records were reviewed, and information was obtained on signalment, history, problems at initial evaluation, physical examination findings, weight and changes in weight while receiving TPN, duration in the hospital before initiation of TPN, the type of TPN catheter used, duration of TPN administration, and final diagnosis. Laboratory results obtained immediately prior to TPN and at 24 and 96 hours following initiation of TPN administration were compared.

RESULTS

Reports of weight loss at initial evaluation, hyperglycemia at 24 hours, or diagnosis of chronic renal failure were significantly associated with increased mortality rate. Greater serum albumin concentrations prior to and at 96 hours following TPN administration were significantly associated with decreased mortality rate. Mechanical and septic complications were infrequent and not associated with increased mortality rate. Most cats had multiple diseases. The overall mortality rate was 52%; among 75 cats, 36 recovered, 23 were euthanatized, and 16 died as a result of their primary illness or complications associated with their illness.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated high mortality rate in cats maintained onTPN that had multiple concurrent diseases associated with a poor prognosis. Indicators of poor prognosis included a history of weight loss, hyperglycemia at 24 hours following TPN administration, hypoalbuminemia, and chronic renal failure.

Hematologic abnormalities in severe neonatal necrotizing enterocolitis: 25 years later

Necrotizing enterocolitis (NEC), the most common surgical emergency in newborns, remains a therapeutic challenge for clinicians. The hematological manifestations associated with NEC were first described 25 years ago. This review discusses current knowledge of the pathophysiology involved in disturbances in megakaryocytopoiesis, coagulation, leukopoiesis, and erythropoiesis that accompany the clinical entity NEC. The discussion includes current understanding of and potential strategies for treating the hematopoietic disturbances that occur secondary to NEC.

Parenteral lipid emulsions and phagocytic systems

Lipid emulsions (LE) for parenteral use are complex emulsions containing fatty acids, glycerol, phospholipids and tocopherol in variable amounts and concentrations. In clinical practice, LE have been employed for more than 30 years. Fatty acids may have different impacts on phagocytic cells according to their structure. Experimental and clinical studies have consistently shown that LE modify monocyte/macrophage and polymorphonuclear phagocytosis. The inhibitory effect of LE on the functional activity of the phagocytic system, although still clinically controversial, may have a harmful impact because total parenteral nutrition with lipids may be recommended in hypercatabolic conditions where inflammation and infection are present. LE based on triglycerides containing long chain fatty acids (termed long chain triglycerides or LCT) are the main parenteral fat source and are typically rich in n-6 polyunsaturated fatty acids. They may have adverse effects on the immune system, especially when given in high doses over a short period of time. However when administered properly they can be used safely. LE containing medium chain triglycerides (MCT) may have some advantages because of their positive effects on polymorphonuclear cells, macrophages, and cytokine production, particularly in critically ill or immunocompromised patients. New parenteral LE containing n-3 polyunsaturated fatty acids or monounsaturated olive oil are already available in Europe. Judicious use of these new LE is mandatory especially relating on their potential impact on the immune system. New experimental and clinical studies are required to further establish the role of LE in clinical nutrition.

Effects of structurally different lipid emulsions on human neutrophil migration

AIM

To test the hypothesis that structurally different lipid emulsions have distinct immunomodulatory properties, we analysed neutrophil migration in the presence of various lipid emulsions.

METHOD

Neutrophils of 8 volunteers were pre-incubated in medium or physiological 2.5 mM emulsions containing long-chain (LCT), medium-chain (MCT), mixed LCT/MCT, alpha -tocopherol-enriched LCT/MCT (LCT/MCT-E) or structured triglycerides (SL). Thereafter, the cells were put on top of 3 microm-pore-sized cell culture filters and incubated for one hour in the presence or absence of a chemo-attractant. Neutrophil migration was measured as the percentage of cells that had passed the filter in the presence (chemotaxis) or absence (random migration) of a chemotactic factor.

RESULTS

Compared to lipid-free incubation (19+/-1%) random neutrophil migration significantly decreased with LCT/MCT (11+/-2%), LCT/MCT-E (12+/-2) and MCT (5+/-2%), while LCT (18+/-3%) and SL (20+/-1%) had no effect. N-formyl-methionyl-leucyl-phenylalanine- (fMLP, 10(-8)M) or zymosan-activated-serum-induced (ZAS, 10%) filter passage under lipid-free conditions amounted to 61+/-14% and 70+/-13%, respectively. These values decreased with LCT/MCT to 11+/-9% and 15+/-7%; with LCT/MCT-E to 18+/-10% and 28+/-12%; with SL to 39+/-18% and 57+/-14%, and with MCT to 5+/-2% and 10+/-6%, (all P<0.01), while LCT had no effect. Compared to LCT/MCT, the alpha -tocopherol-enriched formulation significantly increased ZAS- and fMLP-induced chemotaxis. fMLP-induced chemotaxis decreased in direct proportion to LCT/MCT triglyceride concentration.

CONCLUSIONS

Human neutrophil migration is distinctively inhibited by structurally different lipid emulsions, depending on triglyceride chain-length and concentration as well as alpha -tocopherol content.

Intravenous nutrition and postnatal growth of the micropremie

There is a growing body of evidence that early nutritional practices may affect short-term growth and developmental outcome. In addition, they may play a role in determining adult health and disease. There is much that needs to be learned about safe and efficacious nutrient administration in the ELBW population; about techniques to assess the effect of different nutritional strategies; and about the long-term effects of these regimen or development outcome, growth, and disease.

With medium-chain triglycerides, higher and faster oxygen radical production by stimulated polymorphonuclear leukocytes occurs

BACKGROUND

Parenteral lipid emulsions are suspected of suppressing the immune function. However, study results are contradictory and mainly concern the conventional long-chain triglyceride emulsions.

METHODS

Polymorphonuclear leukocytes were preincubated with parenteral lipid emulsions. The influence of the lipid emulsions on the production of oxygen radicals by these stimulated leukocytes was studied by measuring chemiluminescence. Three different parenteral lipid emulsions were tested: long-chain triglycerides, a physical mixture of medium- and long-chain triglycerides, and structured triglycerides. Structured triglycerides consist of triglycerides where the medium- and long-chain fatty acids are attached to the same glycerol molecule.

RESULTS

Stimulated polymorphonuclear leukocytes preincubated with the physical mixture of medium- and long-chain triglycerides showed higher levels of oxygen radicals (p < .005) and faster production of oxygen radicals (p < .005) compared with polymorphonuclear leukocytes preincubated with long-chain triglycerides or structured triglycerides. Additional studies indicated that differences in results of various lipid emulsions were not caused by differences in emulsifier. The overall production of oxygen radicals was significantly lower after preincubation with the three lipid emulsions compared with controls without lipid emulsion.

CONCLUSIONS

A physical mixture of medium- and long-chain triglycerides induced faster production of oxygen radicals, resulting in higher levels of oxygen radicals, compared with long-chain triglycerides or structured triglycerides. This can be detrimental in cases where oxygen radicals play either a pathogenic role or a beneficial one, such as when rapid phagocytosis and killing of bacteria is needed. The observed lower production of oxygen radicals by polymorphonuclear leukocytes in the presence of parenteral lipid emulsions may result in immunosuppression by these lipids.

The role of phytosterols in the pathogenesis of liver complications of pediatric parenteral nutrition

Long-term parenteral nutrition of infants who have had major gut resections is associated with a high incidence of cholestatic liver disease. Affected infants have high plasma concentrations of phytosterols--compounds that resemble cholesterol but have an alkylated side chain. The phytosterols that accumulate in patients receiving parenteral nutrition are derived from the soya oil and/or soya lecithin used to make the intravenous lipid emulsion. There is a striking association between phytosterolemia and cholestatic liver disease. This has led us to put forward the hypothesis that phytosterols can cause cholestasis in susceptible infants. Experiments using neonatal piglets indicate that phytosterols (given without any of the other components of parenteral nutrition) can indeed reduce bile flow. We suggest that increasing the content of phytosterols in cell membranes may interfere with the function of important transport proteins involved in the secretion of bile. Other factors that might contribute to cholestasis (such as inhibition of cholesterol 7 alpha-hydroxylase) are discussed.

The effect in vitro of high-density lipoprotein from healthy and infected humans on the oxidative metabolism of polymorphonuclear leukocytes

We studied the effects in vitro of high-density lipoprotein from healthy (N-HDL) and from infected humans (AP-HDL) on the oxidative metabolism of human polymorphonuclear leukocytes (PMN). Products of the H2O2-MPO-halide system were monitored by luminol-enhanced chemiluminescence and superoxide anion formation was monitored by lucigenin-enhanced chemiluminescence during stimulation of human PMN with phorbol myristate acetate (PMA) or an opsonized stimulus (OS). The results showed that N-HDL and AP-HDL affect the oxidative metabolism of PMN in different ways. The possible role of this effect is discussed.

Influence of medium-chain triglyceride-based lipid emulsion on rat polymorphonuclear cell functions

Intravenous lipid emulsions are used as energy and essential fatty acids sources. There are controversial reports postulating in vitro and in vivo inhibitory effects of long-chain triglycerides (LCT) upon the blood polymorphonuclear leukocytes (PMNL) functions. In the present study the in vivo and in vitro effects of LCT and a physical mixture of medium- and long-chain triglycerides (MCT/LCT) emulsions were investigated on select PMNL functions, i.e., chemotaxis, phagocytosis, and bacterial killing. Blood from 20 rats was incubated with LCT, MCT, MCT/LCT, and saline, respectively. MCT-containing emulsions exhibited an inhibitory effect on all PMNL functions investigated, whereas LCT exerted an effect on the phagocytic index only. The administration of a parenteral supply of LCT, MCT/LCT, and saline for 30 h followed by saline infusion for 14 h in discontinuous mode did not influence any of the investigated PMNL functions. Similarly, continuous infusion over 44 h at increasing infusion rates up to 1.5 mL/h did not affect the PMNL functions. The obvious difference between in vitro and in vivo response of the PMNL model emphasizes the necessity for continuous monitoring of in vivo conditions. Appropriate interpretation of the data requires continuous circumspection and consideration of trials in a clinical setting.

Restorative effect of total parenteral nutrition on natural killer cell activity in malnourished cancer patients

Decreased natural killer cell activity (NKCA) is associated with malnutrition in both cancer and non-cancer patients. We have studied the effect of total parenteral nutrition (TPN) on NKCA in 9 malnourished cancer patients, candidates for surgery. TPN was administered for a median of 10 days (range 7-11), providing 1.5-fold the estimated resting energy expenditure, with 30% as fat. Calorie:nitrogen ratio was 150:1. Basal human recombinant interferon-alpha 2a (rIFN-alpha 2a) and human recombinant IL-2 rIL-2) activated NKCA were measured, as were the main nutritional parameters, prior to and after TPN. NKCA increased in all patients and reached the normal range in 5, 3 and 4 subjects, respectively, for basal, rIFN-alpha 2a and rIL-2 activated NKCA. As regards nutritional assessment, body weight and IgM levels significantly increased from 47.7 to 50.1 kg and from 174 to 237 mg/dl, respectively. This study demonstrates that a 10-day TPN course increases and sometimes restores normal NKCA. Such effect was constant and preceded nutritional changes.

Long-chain predominant lipid emulsions inhibit in vitro macrophage tumor necrosis factor production

Intravenous lipid emulsions are an important component of parenteral nutrition. Despite their benefits, lipid emulsions have been associated with higher rates of bacteremia in neonates. Therefore we investigated the effect of lipid emulsions on the inflammatory response by examining their effect on in vitro macrophage tumor necrosis factor (TNF) production of two distinct macrophage populations. Through the use of endotoxin-free phosphate buffered saline, peritoneal (PER) and alveolar (ALV) macrophages were isolated from male Sprague-Dawley rats (weighing 125 to 150 g) with endotoxin-free phosphate buffered saline. Cell counts were adjusted to 2 x 10(6) cells/mL in RPMI with 2% fetal calf serum. Three hundred microliters of the cells were incubated in a 24-well culture dish with media or media with intralipid (100 micrograms/dL) for 16 hours. After washing each well three times, the cells were stimulated for 2 or 16 hours with Escherichia coli lipopolysaccharide (150 microL of 1 microgram/mL). The supernatants were assayed for TNF using the WEHI 164:13 bioassay and TNF levels were expressed as picograms per milliliter. Student's unpaired t test was used for data analysis. Lipid-exposed PER and ALV macrophages in vitro TNF levels were significantly lower-after 2 hours (12,591 pg/mL +/- 3837 vs 20,591 pg/mL +/- 6344 for PER, 3894 pg/mL +/- 1258 vs 13,177 pg/mL +/- 3266 for ALV) and 16 hours (6427 pg/mL +/- 3050 vs 12,353 pg/mL +/- 4877 for PER; 131,6000 pg/mL +/- 7317 vs 354,680 pg/mL +/- 31,605 for ALV) of endotoxin stimulation. TNF production seems to be impaired in macrophages exposed to a .1% lipid emulsion for 16 hours.(ABSTRACT TRUNCATED AT 250 WORDS)

Lymphocyte and granulocyte function in nutritionally depleted patients. The effect of 2 weeks of total parenteral nutrition

Parenteral nutrition has been reported to restore impaired immune function in nutritionally depleted patients. Lymphocyte and granulocyte function were studied before and after 2 weeks of total parenteral nutrition (TPN) in 9 depleted patients, 5 with gastrointestinal cancer and 4 with benign gastrointestinal disorders. The ability of purified blood lymphocytes to incorporate (14)C-labelled thymidine spontaneously and following mitogenic and antigenic stimulation was studied. Before TPN spontaneous lymphocyte activity was significantly increased and mitogen and antigen responsiveness significantly decreased in comparison to healthy controls. These abnormalities were more pronounced in patients with malignant disorders while the remaining patients showed a moderate impairment. No improvement in lymphocyte capacity was observed following 2 weeks of TPN. Granulocyte function measured as chemotaxis, phagocytosis, NBT-reduction and bactericidal capacity did not differ significantly between patients and controls and no changes were seen following nutritional treatment. These findings support the concept that the underlying disease and/or other factors rather than the secondary nutritional depletion are the main reasons for immune impairment. Furthermore, no immunomodulating effects of lipid emulsions on lymphocyte and granulocyte function, under these experimental conditions, were apparent.

Effect of different dietary triglycerides on liver fatty acids and prostaglandin synthesis by mouse peritoneal cells

The effect of dietary triglycerides varying in fatty acid composition on the tissue fatty acids and prostaglandin synthesis was studied in mice. The dietary fats were medium-chain triglycerides (rich in C8:0 and C10:0), structured lipids (rich in 12:0), high oleic sunflower oil (rich in 18:1), corn oil (rich in n-6 polyunsaturated fatty acids), and menhaden oil (rich in n-3 polyunsaturated fatty acids) fed at 5% by weight in refined diets. The medium chain fatty acids C8 to C12 from medium-chain triglycerides and structured lipids did not accumulate in liver phospholipids. However, long-chain fatty acids from the dietary fats were incorporated into liver lipids, with n-3 polyunsaturated fatty acids replacing arachidonic acid. The synthesis of 6-keto-prostaglandin F1 alpha and prostaglandin E2 by peritoneal cells in response to intraperitoneal injection of zymosan decreased as the arachidonic acid levels were decreased. When the same dietary fats were added to the refined, fat-free diets, at 7.5 wt% levels, together with 2.5 wt% of safflower oil to provide essential fatty acids, only the long-chain fatty acids from the dietary fats were incorporated into the liver lipids. The arachidonic acid in liver lipids was enhanced after supplementation of diets with safflower oil. However, the reduction in prostaglandin synthesis by peritoneal cells in response to intraperitoneal injection of zymosan was similar to that observed when 5% fat was fed. The data suggest that dietary fats of defined composition, with or without added essential fatty acids, may be useful as alternate fat sources in parenteral nutrition in reducing inflammatory responses mediated via prostaglandins.