Effect of omega-3 polyunsaturated fatty acids in modulation of vascular tone under physiological and pathological conditions

Omega-3 polyunsaturated fatty acids (n-3 PUFAs), including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are mainly found in marine fish oils and commercially available fish oil supplements. Several studies have documented that n-3 PUFAs can reduce the risk of cardiovascular diseases through anti-inflammatory, anti-thrombotic, and anti-atherosclerotic properties. Notably, regulation of vascular tone is one of the most important bases of cardiovascular health and especially for maintaining blood pressure within optimal physiological ranges. Recent clinical and animal studies indicate an association between n-3 PUFAs and vascular functions. In this regard, many clinical trials and basic experimental studies have been conducted so far to investigate the influence of n-3 PUFAs on vascular tone. In this review, we have summarized the results obtained from both clinical and basic studies that evaluated the effect of n-3 PUFAs under physiological and pathological conditions. Moreover, we also focus on verifying the underlying basic molecular mechanism of n-3 PUFAs on the vascular system.

Early parenteral nutrition in neonates with congenital diaphragmatic hernia

BACKGROUND

The ideal nutritive strategy for a neonate with congenital diaphragmatic hernia (CDH) has not been elucidated. The purpose of this study was to investigate the efficacy of early parenteral nutrition (PN) in CDH neonates.

METHODS

Thirty-five CDH neonates admitted to a single hospital from January 2005 to December 2014 were retrospectively reviewed. For the first 4 years of the study period, neonates received non-early PN (n-EPN) (2005-2008, amino acids [AA] <1.0 g/kg/day, no lipids administered). After the transitional period (TP) (2009-2011, AA 1.0-2.5 g/kg/day, lipid 1.0 g/kg/day), early PN (EPN) (2011-2014, AA ≥3.0 g/kg/day, lipid 1.0 g/kg/day) was performed. We investigated the clinical effect of PN for growth-associated clinical variables and the outcomes.

RESULTS

The first day of AA administration was late in the n-EPN period (6.0 ± 4.6, 0.0 ± 0.8, 0.1 ± 0.3 ; n-EPN, TP, EPN: in order). The final day of PN (11.0 ± 3.7, 9.2 ± 4.0, 12.4 ± 3.9) and the first day of enteral feeding (4.5 ± 1.9, 4.3 ± 1.4, 4.5 ± 3.2), the first day of full milk feeding (100 mL/kg/day) (10.8 ± 5.4, 9.2 ± 2.3, 11.5 ± 3.5) were statistically equal in every period. The date and body weight at discharge showed no significant differences among the three groups, but the weight-gain rate from birth to discharge was higher in the EPN group than in the n-EPN group (P = 0.023). The rate of inhaled nitric oxide (NO) gas administration and the duration of ventilation showed no significant differences among the three groups. Severe PN-associated liver disease was not noted during the observation period.

CONCLUSIONS

Early PN for CDH neonates promotes weight gain in the neonatal intensive-care unit. The long-term efficacy and safety of EPN for CDH neonates should be elucidated by additional studies.

Intestinal absorption of lipid emulsion in premature infants: a pilot study

BACKGROUND

Adequate nutritional intake is essential in the very-low-birth-weight infant, but difficult to achieve in the first few postnatal days. Can lipids be given enterally in the first few days of life in sick preterm infants?

OBJECTIVE

To determine tolerance and absorption of lipid emulsion when fed enterally to very-low-birth-weight infants.

DESIGN/METHODS

Infants had a birth weight <1,500 g, an appropriate weight for gestational age, and were receiving parenteral nutrition. We performed a progressive series of studies, enrolling 5 infants in each group. Group 1 infants were fed enteral lipid emulsion at 1 g/kg/day for 4 days, starting when 60 ml/kg/day of breast milk was tolerated enterally. Simultaneously, a matched control group which received no oral lipid emulsion was enrolled. We then enrolled group 2 infants who were fed 3 g/kg/day with the same protocol as group 1. Group 3 infants were fed enteral lipid emulsion starting in the first 72 h of life. The infants were fed 1, 2 and 3 g/kg/day subsequently for 48 h each. Fat absorption was measured.

RESULTS

Gestational age was 24.6-30.8 weeks and birth weight was 620-1,400 g. One infant (group 1) developed necrotizing enterocolitis 1 week after the study. There were no other adverse clinical findings. On average, enteral lipid emulsion was started on day 8 of life in groups 1 and 2, and on day 2 in group 3. The intestinal lipid absorption was 93.6% (min. = 76%). There was no difference in fat absorption between the 4 groups (p > 0.05).

CONCLUSIONS

Lipid emulsions are an isotonic high-calorie source which can be given safely enterally instead of intravenously in the immediate neonatal period of very-low-birth-weight infants without clinical adverse effects and with almost complete absorption. There are potential advantages to oral administration of a lipid emulsion starting in early life which require further investigation.

Enteral feeding induces diet-dependent mucosal dysfunction, bacterial proliferation, and necrotizing enterocolitis in preterm pigs on parenteral nutrition

Preterm neonates have an immature gut and metabolism and may benefit from total parenteral nutrition (TPN) before enteral food is introduced. Conversely, delayed enteral feeding may inhibit gut maturation and sensitize to necrotizing enterocolitis (NEC). Intestinal mass and NEC lesions were first recorded in preterm pigs fed enterally (porcine colostrum, bovine colostrum, or formula for 20-40 h), with or without a preceding 2- to 3-day TPN period (n = 435). Mucosal mass increased during TPN and further after enteral feeding to reach an intestinal mass similar to that in enterally fed pigs without TPN (+60-80% relative to birth). NEC developed only after enteral feeding but more often after a preceding TPN period for both sow's colostrum (26 vs. 5%) and formula (62 vs. 39%, both P < 0.001, n = 43-170). Further studies in 3-day-old TPN pigs fed enterally showed that formula feeding decreased villus height and nutrient digestive capacity and increased luminal lactic acid and NEC lesions, compared with colostrum (bovine or porcine, P < 0.05). Mucosal microbial diversity increased with enteral feeding, and Clostridium perfringens density was related to NEC severity. Formula feeding decreased plasma arginine, citrulline, ornithine, and tissue antioxidants, whereas tissue nitric oxide synthetase and gut permeability increased, relative to colostrum (all P < 0.05). In conclusion, enteral feeding is associated with gut dysfunction, microbial imbalance, and NEC in preterm pigs, especially in pigs fed formula after TPN. Conversely, colostrum milk diets improve gut maturation and NEC resistance in preterm pigs subjected to a few days of TPN after birth.

Effects of Intralipid infusion on hemorheology and peripheral resistance in neonates and children

Deleterious microcirculatory effects of Intralipid (IL) infusion may be caused by hemorheological or vascular effects. The aim of this investigation was to study vascular and hemorheological effects of IL in preterm and fullterm neonates and children. Ten preterm newborns, 10 fullterm neonates, and 10 children received an initial infusion of IL (0.6 g/kg) over 4 h. Calf blood flow (venous occlusion plethysmography), blood pressure (Dinamap), whole blood and plasma viscosity (capillary viscometer), red blood cell deformability (rheoscope), and erythrocyte aggregation (aggregometer) were measured before and after administration of IL. Plasma triglyceride levels showed the greatest increase in preterm infants. Whole blood viscosity decreased by about 10% in all three groups because of a similar reduction in hematocrit. Red blood cell aggregation decreased by about 20% after IL infusion. Blood pressure rose by 10%, and peripheral blood flow declined by about 10% in the three groups. Vascular hindrance, a calculation of blood pressure divided by blood flow and viscosity, was raised by about 20%, suggesting marked vasoconstriction of peripheral arteries. Vasoconstriction rather than hemorheological changes during infusion of IL may play a crucial role in the pathogenesis of circulatory alterations in parenterally-fed neonates.

Propofol does not induce pulmonary dysfunction in stressed endotoxic pigs receiving Intralipid

OBJECTIVE

To assess the effect of diisopropyl phenol (propofol), with and without Intralipid, on the cardiopulmonary system and on thromboxane production in endotoxic pigs.

DESIGN

Prospective, randomized animal study.

SETTING

Animal research laboratory at a major teaching hospital.

SUBJECTS

Twenty-four pigs, divided into three groups (n = 8).

INTERVENTIONS

Pulmonary arterial catheters and arterial cannulas were inserted into all pigs. Each pig received a 30 ng/kg bolus of endotoxin at 1 hr, followed by a continuous infusion of endotoxin at 24 ng x kg-1 x hr-1. Diisopropyl phenol at 25, 75, and 200 microg x kg-1 x min-1 was administered to all pigs, beginning at 1, 2, and 3 hrs, respectively. The pigs were divided into three groups to receive 0.25 g x kg-1 x hr-1, 0.08 g x kg-1 x hr-1, or no Intralipid, starting at time t = 0. Heart rate and mean arterial, central venous, and pulmonary arterial pressures were recorded continuously. Core temperature, arterial blood gases, mixed venous oxygen saturation, pulmonary arterial occlusion pressure, and cardiac output were measured intermittently. Thromboxane B(2) concentrations were measured at baseline and at 60, 75, 120, 135, 180, 195, and 240 mins. Data are expressed as mean +/- sd. Groups were compared by using repeated analysis of variance, with p <.05 used for statistical significance.

MEASUREMENTS AND MAIN RESULTS

All pigs completed the 4-hr study. Marked variabilities were noted for individual pigs. Following the infusion of endotoxin, compared with baseline, there was a significant increase in pulmonary vascular resistance and a decrease in Pao(2) (p <.001 and p <.008, respectively). This response was not affected by the increasing dose of diisopropyl phenol, nor were there differences between the Intralipid and control groups. Pao(2) remained significantly lower in all groups, compared with the baseline measurements (p <.001) over the 4 hrs of the experiment. Thromboxane B(2) concentrations remained elevated compared with baseline and were significantly higher (p <.05) in the high-dose Intralipid group, compared with the low-dose and the control groups, during the last hour of the experiment.

CONCLUSIONS

Small doses of endotoxin, when given to pigs, induce major perturbations of cardiopulmonary function. Neither Intralipid, high vs. low dose, nor diisopropyl phenol, at sedating vs. anesthetizing doses, worsened the physiologic derangement associated with the stress of low-dose endotoxemia.