Television food advertisement exposure and FTO rs9939609 genotype in relation to excess consumption in children.

BACKGROUND/OBJECTIVE: Exposure to food advertisements may cue overeating among children, especially among those genetically predisposed to respond to food cues. We aimed to assess how television food advertisements affect eating in the absence of hunger among children in a randomized trial. We hypothesized that the fat mass and obesity-associated gene (FTO) rs9939609 single-nucleotide polymorphism would modify the effect of food advertisements. SUBJECTS/METHODS: In this randomized experiment, 200 children aged 9-10 years were served a standardized lunch and then shown a 34-min television show embedded with either food or toy advertisements. Children were provided with snack food to consume ad libitum while watching the show and we measured caloric intake. Children were genotyped for rs9939609 and analyses were conducted in the overall sample and stratified by genotype. A formal test for interaction of the food advertisement effect on consumption by rs9939609 was conducted. RESULTS: About 172 unrelated participants were included in this analysis. Children consumed on average 453 (s.d.=185) kcals during lunch and 482 (s.d.=274) kcals during the experimental exposure. Children who viewed food advertisements consumed an average of 48 kcals (95% confidence interval: 10, 85; P=0.01) more of a recently advertised food than those who viewed toy advertisements. There was a statistically significant interaction between genotype and food advertisement condition (P for interaction=0.02), where the difference in consumption of a recently advertised food related to food advertisement exposure increased linearly with each additional FTO risk allele, even after controlling for body mass index percentile. CONCLUSIONS: Food advertisement exposure was associated with greater caloric consumption of a recently advertised food, and this effect was modified by an FTO genotype. Future research is needed to understand the neurological mechanism underlying these associations.

Room temperature housing results in premature cancellous bone loss in growing female mice: implications for the mouse as a preclinical model for age-related bone loss.

UNLABELLED: Room temperature housing (22 °C) results in premature cancellous bone loss in female mice. The bone loss was prevented by housing mice at thermoneutral temperature (32 °C). Thermogenesis differs markedly between mice and humans and mild cold stress induced by standard room temperature housing may introduce an unrecognized confounding variable into preclinical studies. INTRODUCTION: Female mice are often used as preclinical models for osteoporosis but, in contrast to humans, mice exhibit cancellous bone loss during growth. Mice are routinely housed at room temperature (18-23 °C), a strategy that exaggerates physiological differences in thermoregulation between mice (obligatory daily heterotherms) and humans (homeotherms). The purpose of this investigation was to assess whether housing female mice at thermoneutral (temperature range where the basal rate of energy production is at equilibrium with heat loss) alters bone growth, turnover and microarchitecture. METHODS: Growing (4-week-old) female C57BL/6J and C3H/HeJ mice were housed at either 22 or 32 °C for up to 18 weeks. RESULTS: C57BL/6J mice housed at 22 °C experienced a 62 % cancellous bone loss from the distal femur metaphysis during the interval from 8 to 18 weeks of age and lesser bone loss from the distal femur epiphysis, whereas cancellous and cortical bone mass in 32 °C-housed mice were unchanged or increased. The impact of thermoneutral housing on cancellous bone was not limited to C57BL/6J mice as C3H/HeJ mice exhibited a similar skeletal response. The beneficial effects of thermoneutral housing on cancellous bone were associated with decreased Ucp1 gene expression in brown adipose tissue, increased bone marrow adiposity, higher rates of bone formation, higher expression levels of osteogenic genes and locally decreased bone resorption. CONCLUSIONS: Housing female mice at 22 °C resulted in premature cancellous bone loss. Failure to account for species differences in thermoregulation may seriously confound interpretation of studies utilizing mice as preclinical models for osteoporosis.

Thin and hypokinetic myocardial segments in cats with cardiomyopathy.

INTRODUCTION/OBJECTIVES: Thin and hypokinetic myocardial segments (THyMS) represent adverse ventricular (LV) remodeling in human hypertrophic cardiomyopathy. We describe the echocardiographic features and outcome in cats with THyMS, and in a subpopulation, the echocardiographic phenotype before LV wall thinning was detected (pre-THyMS). ANIMALS: Eighty client-owned cats. MATERIALS AND METHODS: Retrospective multicenter study. Clinical records were searched for cats with THyMS, defined as LV segment(s) with end-diastolic wall thickness (LVWT) <3 mm and hypokinesis in the presence of ≥one LV segment(s) with LVWT >4 mm and normal wall motion. When available, echocardiograms pre-THyMS were assessed. Survival time was defined as time from first presentation with THyMS to death. RESULTS: Mean thickest LV wall segment (MaxLVWT) was 6.1 mm (95% CI 5.8-6.4 mm) and thinnest (MinLVWT) was 1.7 mm (95% CI 1.6-1.9 mm). The LV free wall was affected in 74%, apex in 13% and septum in 5%. Most cats (85%) presented with heart failure and/or arterial thromboembolism. Median circulating troponin I concentration was 1.4 ng/mL ([range 0.07-180 ng/mL]). Prior echocardiography results were available for 13/80 cats, a mean of 2.5 years pre-THyMS. In segments subsequently undergoing thinning, initial MaxLVWT measured 6.7 mm (95% CI 5.8-7.7 mm) vs. 1.9 mm (95% CI 1.5-2.4 mm) at last echocardiogram (P<0.0001). Survival data were available for 56/80 cats, median survival time after diagnosing THyMS was 153 days (95% CI 83-223 days). Cardiac histopathology in one cat revealed that THyMS was associated with severe transmural scarring. CONCLUSIONS: Cats with THyMS had advanced cardiomyopathy and a poor prognosis.

[Smoking in movies and established smoking in adolescence]. / Rauchen in Filmen und Etablierung des Rauchens im Jugendalter.

AIM: The aim of this study was to examine whether smoking in movies can predict established smoking in adolescence. METHODS: A longitudinal study was conducted over a period of 13 months with 4112 German students. Adolescents' exposure to smoking in movies was assessed by asking each student to indicate which film he or she had seen from a unique list of 50 movies, which was randomly selected for each individual survey from a sample of 398 popular contemporary movies. We calculated exposure to movie smoking for each respondent by summing the number of smoking occurrences for each movie that the respondent reported seeing. RESULTS: At follow-up, a total of 272 young people had smoked more than 100 cigarettes during their lifetime. While 2.1% of the young people with the lowest exposure to movie smoking initiated established smoking, 13.4% of the group with the highest exposure to movie smoking initiated established smoking. The adjusted relative risk of initiation of established smoking was 2.05 times higher in the group with the highest movie smoking exposure compared to the group with the lowest exposure (95% confidence interval: 1.25-3.35). CONCLUSION: Our data indicate that smoking in movies can be regarded as an independent risk factor for the initiation of established smoking in adolescence.

The next heartbeat: Creating dynamic and histographic Poincaré plots for the assessment of cardiac rhythms.

The rhythm of the heart is not a stationary phenomenon, and therefore, incorporation of the dynamic Poincaré plot and tachogram provides additional diagnostic information to complement and expand waveform (P-QRST) analyses from the electrocardiogram. Although pattern assessment of the Poincaré plot and tachogram can provide an appraisal for normal and abnormal rhythms and serve as a potential means for machine-learned rhythm diagnoses, time-selected windows of beat-to-beat variability permit more detailed examination. As such, expanded criteria for rhythm diagnoses, identification of arrhythmic triggers, global appreciation of rhythm changes, and recognition of patterns that provoke mechanistic questions may be gleaned from the use of the methods reviewed in this report. More specifically, these methods demonstrate that limitations exist in the reliance on traditional measures of heart rate variability in the dog due to the non-linear beat-to-beat rhythm of sinus arrhythmia in the species. Behavior of arrhythmias based on coupling intervals, repeating patterns, preceding triggers of beat-to-beat variability, and circumstantial evidence of atrioventricular nodal conduction during atrial flutter and fibrillation are a few examples of discovery founded in these techniques. The open access website, The Next Heartbeat (https://thenextheartbeat.com/), permits anyone to implement these methods in the assessment of long-term electrocardiographic examinations (Holter monitoring) so that, as yet to be revealed, features of the beating heart through time may be discovered.

The use of Amplatzer vascular plug II in 32 consecutive dogs for transvenous occlusion of patent ductus arteriosus.

OBJECTIVES: To describe the use of the Amplatzer vascular plug II (AVPII) for transvenous occlusion of patent ductus arteriosus in a non-selective population of dogs, with a focus on the surgical technique, short term outcome and associated complications. ANIMALS, MATERIALS AND METHODS: Retrospective study. Records of thirty-two consecutive dogs treated for a left-to-right shunting patent ductus arteriosus with the AVPII were reviewed. RESULTS: Ductal occlusion with an AVPII occlusion device was attempted in 32 dogs weighing 1.1-53.8 kg. Transvenous occlusion was successful in 30 dogs. One dog required a transarterial approach for occlusion. One dog died during catheterisation of the right heart but prior to transductal catheterisation. Mean ductal ampulla diameter was 7.9 mm (range, 4.1-15.4 mm) and median size of deployed devices was 10 mm (range 4-20 mm). Mean device to ampulla ratio was 1.34 ± 0.15. Device was positioned in situ with no residual flow on follow-up echocardiographic assessment (> one month) in all dogs where deployment was attempted. Occlusion success rate was 96.9% and mortality rate was 3.1%. Four dogs (13.3%) demonstrated minor complications, with none having long-term significance. CONCLUSIONS: The use of AVPII device via a transvenous approach is a feasible and effective method for occlusion of a left-to-right shunting patent ductus arteriosus in dogs of a wide range of weight. The method described may complement existing catheter-based occlusion methods.

Segmental septal dyskinesia associated with an accessory pathway and preexcitation in two Golden Retriever dogs.

Ventricular preexcitation secondary to anterograde conduction through an accessory pathway was diagnosed in two Golden Retriever dogs. Both dogs demonstrated similar segmental myocardial thinning and systolic dyskinesia of the basal interventricular wall on echocardiography. These changes are widely recognised in people with ventricular preexcitation but have not been previously described in dogs. Ventricular preexcitation should be considered as a potential cause for segmental wall motion abnormalities in these two dogs.

Supraventricular tachycardia in 23 cats; comparison with 21 cats with atrial fibrillation (2004-2014).

INTRODUCTION: Supraventricular tachycardia (SVT) has not been well described in cats. The aim of this study was to describe the signalment, clinical findings, and outcome for cats with SVT versus cats with atrial fibrillation (AF). ANIMALS: Forty-four client owned cats are included in the study. 23 cats with SVT and 21 with AF. METHODS: This is a retrospective study. Clinical characteristics were compared between groups using a two-sample t-test or Mann-Whitney U test. Kaplan-Meier survival curves were generated to assess for impact of rhythm diagnosis, presence of ventricular arrhythmia, left atrial diameter, heart rate and congestive heart failure (CHF) status on cardiac death. Differences in survival between groups were compared using Mantel-Cox logrank comparison of Kaplan-Meier survival curves. RESULTS: Cats with supraventricular arrhythmias most commonly presented with respiratory distress (10 of 44 cats). Cats with AF had a slower median heart rate (220 [range: 180-260 beats per minute (bpm)] compared with cats with SVT (300 [range: 150-380] bpm, p < 0.001). All cats with AF had structural heart disease, whereas 4 cats with SVT had no structural abnormalities. Left atrial diameter was significantly larger in cats with AF (23.7 (16.2-40.1) mm compared with 19.1 (12.8-31.4) mm in SVT cats; p = 0.02). Median survival was 58 days (1-780) in cats with AF and 259 days (2-2295) in cats with SVT (p = 0.1). Cats with signs of CHF had a shorter survival time (p = 0.001). CONCLUSIONS: Most cats with AF or SVT have advanced structural heart disease. Some cats with SVT had structurally normal hearts, suggesting that SVT in cats is not always a consequence of atrial enlargement.

Comparing the effects of entertainment media and tobacco marketing on youth smoking.

OBJECTIVES: To examine the concurrent effects of exposure to movie smoking and tobacco marketing receptivity on adolescent smoking onset and progression. METHODS: Cross-sectional study of 4524 northern New England adolescents aged 10-14 in 1999 with longitudinal follow-up of 2603 baseline never-smokers. Cross-sectional outcomes included ever tried smoking and higher level of lifetime smoking among 784 experimenters. The longitudinal outcome was onset of smoking among baseline never-smokers two years later. Movie smoking exposure was modelled as four population quartiles, tobacco marketing receptivity included two levels-having a favourite tobacco advert and wanting/owning tobacco promotional items. All analyses controlled for sociodemographics, other social influences, personality characteristics of the adolescent and parenting style. RESULTS: In the full cross-sectional sample, 17.5% had tried smoking; both exposure to movie smoking and receptivity to tobacco marketing were associated with having tried smoking. Among experimental smokers, the majority (64%) were receptive to tobacco marketing, which had a multivariate association with higher level of lifetime smoking (movie smoking did not). In the longitudinal study 9.5% of baseline never-smokers tried smoking at follow-up. Fewer never-smokers (18.5%) were receptive to tobacco marketing. Movie smoking had a multivariate association with trying smoking (receptivity to tobacco marketing did not). CONCLUSIONS: The results suggest separate roles for entertainment media and tobacco marketing on adolescent smoking. Both exposures deserve equal emphasis from a policy standpoint.

Clarification and confocal imaging of the nonhuman primate placental micro-anatomy.

Geometry of the placental villous vasculature is a key determinant of maternal-fetal nutrient exchange for optimal fetal growth. Recent advances in tissue clarification techniques allow for deep high-resolution imaging with confocal microscopy; however, the methodology lacks a signal:noise ratio of sufficient magnitude to allow for quantitative analysis. Thus, we sought to develop a reproducible method to investigate the 3D vasculature of the nonhuman primate placenta for subsequent data analysis. Fresh placental tissue was dissected, formalin fixed, clarified using a modified Visikol® protocol and immunolabeled for CD31 (fetal endothelium) and cytokeratin-7 (villous trophoblast) for confocal imaging of the microanatomy. We present a detailed clarification and staining protocol augmented for imaging of nonhuman primate placental tissue. The image stacks generated by this refined staining method and our data acquisition parameters can be analyzed quantitatively to provide insights regarding the villous and vascular micro-anatomy of the placenta.

Surgical treatment of pulmonic stenosis in dogs under cardiopulmonary bypass: outcome in nine dogs.

OBJECTIVES: To describe the outcome for nine dogs with pulmonic stenosis treated by open patch grafting using expanded polytetrafluoroethylene under cardiopulmonary bypass. MATERIALS AND METHODS: Data were collected from the hospital records of all dogs that had undergone right ventricular outflow tract grafting with an expanded polytetrafluoroethylene patch under cardiopulmonary bypass between 2006 and 2012 for the treatment of pulmonic stenosis. Echocardiographic images were reviewed and the pressure gradient across the right ventricular outflow tract re-measured. Owners of dogs still alive at the time of writing were invited to return to the hospital for reassessment. RESULTS: Nine dogs met the inclusion criteria. Median pressure gradient preoperatively was 118 mmHg, (range 102 to 259 mmHg) reducing to a median of 20 mmHg (range 7 to 53 mmHg) at 48 hours postoperatively and 14 mmHg (range 10 to 70 mmHg), with a median percentage reduction of 89% (range 41 to 94%) at long-term follow-up. Eight of nine dogs survived surgery, with six of nine surviving to hospital discharge. Two dogs were still alive over 6 and 8 years postoperatively. No long-term deaths were believed to be attributable to pulmonic stenosis. CLINICAL SIGNIFICANCE: Expanded polytetrafluoroethylene patch grafting of the right ventricular outflow tract for treatment of severe pulmonic stenosis in dogs is feasible and can be an effective method to reduce the severity of right ventricular outflow tract obstruction.

Phenotypic description of cardiac findings in a population of Dogue de Bordeaux with an emphasis on atrial fibrillation.

The aim of this study was to describe the clinical phenotype of Dogue de Bordeaux (DdB) referred for cardiac investigation, with particular reference to the prevalence of atrial fibrillation and associated features. Review of canine medical records of two United Kingdom veterinary referral hospitals identified 64 DdB with available echocardiographic and electrocardiographic (ECG)/Holter data. Atrial fibrillation was documented in 25 (39%) dogs and supraventricular tachycardia was recorded in five (7.8%) dogs. In a subset of 34 dogs, excluding congenital heart disease (n=17), presence of a cardiac mass (n=7) and non-cardiac neoplasia (n=6), 19 (56%) dogs had atrial fibrillation, with a median heart rate of 200 beats per min (bpm) on presentation. Atrial fibrillation was inconsistently associated with cardiac chamber remodelling, but was frequently associated with systolic dysfunction (13/19, 68.4%) and right sided atrial or ventricular dilatation (14/19, 73.7%) in dogs with atrial fibrillation in this subset. No dogs in this subset had right sided atrial or ventricular dilatation in the absence of supraventricular arrhythmia or systolic dysfunction. The absence of structural heart disease in some dogs with supraventricular arrhythmias suggests that an underlying primary arrhythmic process might be responsible for initiating remodelling, although a primary cardiomyopathy cannot be ruled out.

Dialysis in the 1960s and the first hollow fiber dialyzer.

The history of the development of the first hollow fiber dialyzer as part of a federally funded project at Dow Chemical in Walnut Creek, California is interesting, as this project represented an initial step in the technical advances that dialysis has experienced over the last 40 years. The project, important in its own right, was revolutionary; the predominant design of dialyzers in use at the time employed either flat membranes or collapsed large cellulose tubing. The hollow fiber dialyzer project, in addition to being technologically important, brought together several individuals who over the intervening four decades have launched careers and collaborations that have had a profound impact, as well as resulting in major advances and contributions to a greater understanding of the dialysis process and adequate delivery of care.

Warfarin prevalence, indications for use and haemorrhagic events.

Warfarin, the standard oral anticoagulant drug used in Ireland, is a widely prescribed medication, particularly in the elderly. A HSE Mid-Western Area wide audit was undertaken over a 12-month period to examine the prevalence and indications for warfarin use and haemorrhagic complications associated with the drug. Every patient receiving warfarin therapy over a 13-week period was included (2564). The age standardised rate varied from 0.09% of 35-39 year olds to 6.1% of 80-84 year olds. Atrial fibrillation was the most common indication (54%) in patients attending the Mid-Western Regional Hospital anticoagulation clinic. The annual cumulative incidence of adverse haemorrhagic events in patients with a recorded INR > or = 5.0 episode was 16.6%. The incidence of major and minor haemorrhagic events per INR > or = 5.0 episode was 1.3% and 15.3% respectively. The most common sites of haemorrhage were genitourinary (39%) and gastrointestinal (27%). No fatal or intracranial haemorrhage relating to episodes of over-anticoagulation were reported during the audit period. The most frequent reason for over-anticoagulation was drug interaction (43%). In 74% of patients, the elevated INR was reversed by omitting or reducing warfarin dose. In 17% of cases, vitamin K was administered. Only 3% of incidents were treated with fresh frozen plasma or prothrombin complex concentrates.

Outcome of bioprosthetic valve replacement in dogs with tricuspid valve dysplasia.

OBJECTIVES: To describe the short-term and long-term outcome in dogs with tricuspid valve dysplasia undergoing tricuspid valve replacement under cardiopulmonary bypass. METHODS: Data were collected from the hospital records of all dogs that had undergone tricuspid valve replacement under cardiopulmonary bypass between 2006 and 2012. Dogs were considered candidates for tricuspid valve replacement if they had severe tricuspid valve regurgitation associated with clinical signs of cardiac compromise. RESULTS: Nine dogs of six different breeds were presented. Median age was 13 months (range 7 to 61 months), median weight 26·5 kg (range 9·7 to 59 kg). Eight bovine pericardial valves and one porcine aortic valve were used. One non-fatal intraoperative complication occurred. Complications during hospitalisation occurred in six dogs, four of which were fatal. Of the five dogs discharged, one presented dead due to haemothorax after minor trauma seven days later. The four remaining dogs survived a median of 533 days; all of these dogs received a bovine pericardial valve. CLINICAL SIGNIFICANCE: Based on our results, tricuspid valve replacement with bovine or porcine prosthetic valves is associated with a high incidence of complications.

Differentiation of Cardiac from Noncardiac Pleural Effusions in Cats using Second-Generation Quantitative and Point-of-Care NT-proBNP Measurements.

BACKGROUND: Pleural effusion is a common cause of dyspnea in cats. N-terminal pro-B-type natriuretic peptide (NT-proBNP) measurement, using a first-generation quantitative ELISA, in plasma and pleural fluid differentiates cardiac from noncardiac causes of pleural effusion. HYPOTHESIS/OBJECTIVES: To determine whether NT-proBNP measurements using second-generation quantitative ELISA and point-of-care (POC) tests in plasma and pleural fluid distinguish cardiac from noncardiac pleural effusions and how results compare to the first-generation ELISA. ANIMALS: Thirty-eight cats (US cohort) and 40 cats (UK cohort) presenting with cardiogenic or noncardiogenic pleural effusion. METHODS: Prospective cohort study. Twenty-one and 17 cats in the US cohort, and 22 and 18 cats in the UK cohort were classified as having cardiac or noncardiac pleural effusion, respectively. NT-proBNP concentrations in paired plasma and pleural fluid samples were measured using second-generation ELISA and POC assays. RESULTS: The second-generation ELISA differentiated cardiac from noncardiac pleural effusion with good diagnostic accuracy (plasma: sensitivity, 95.2%, specificity, 82.4%; pleural fluid: sensitivity, 100%, specificity, 76.5%). NT-proBNP concentrations were greater in pleural fluid (719 pmol/L (134-1500)) than plasma (678 pmol/L (61-1500), P = 0.003), resulting in different cut-off values depending on the sample type. The POC test had good sensitivity (95.2%) and specificity (87.5%) when using plasma samples. In pleural fluid samples, the POC test had good sensitivity (100%) but low specificity (64.7%). Diagnostic accuracy was similar between first- and second-generation ELISA assays. CONCLUSIONS AND CLINICAL IMPORTANCE: Measurement of NT-proBNP using a quantitative ELISA in plasma and pleural fluid or POC test in plasma, but not pleural fluid, distinguishes cardiac from noncardiac causes of pleural effusion in cats.

Incorporation of [1-14C]arachidonic and [1-14C]eicosapentaenoic acids into the phospholipids of peripheral blood neutrophils from the plaice, Pleuronectes platessa L.

The incorporation of [1-14C]arachidonic acid and [1-14C]eicosapentaenoic acids into phospholipids was studied in peripheral blood neutrophils from plaice, a marine fish whose lipids are rich in (n-3) polyunsaturated fatty acids. The incorporation of both labelled fatty acids into phospholipids was approximately equal when presented individually, and at equal concentration, to the cells. Arachidonic acid was relatively preferred when both acids were present in the incubations. When incorporation was expressed per unit mass of phospholipid class, the order of incorporation was PI greater than PC greater than PE greater than PS greater than sphingomyelin for both fatty acids. However, the specificity for incorporation into PI was significantly greater with arachidonic acid. Eicosapentaenoic acid was incorporated into PC to a greater extent than arachidonic acid. The results are discussed in relation to the possible roles of arachidonic acid and eicosapentaenoic acid in polyunsaturated fatty acid metabolism in plaice neutrophils.

Biosynthesis of triacylglycerols in the intestines of rainbow trout (Salmo gairdnerii) fed marine zooplankton rich in wax esters.

Intestinal preparations from rainbow trout fed a diet rich in wax esters incorporated [1(-14)C]hexadecanoic acid and [1(-14)C]hexadecanol into triacylglycerols at the same rate. The ratio of the number of H atoms from C1 of hexadecanol to the number of molecules of hexadecanol incorporated into triacylglycerols was 1.6 : 3.0. [U-14C]Glucose was incorporated much faster into the glycerol moiety of triacylglycerols than was [U-14C]aspartic acid. We conclude that the oxidation of absorbed fatty alcohol to fatty acid and its subsequent incorporation into triacylglycerols is closely linked with the reductive formation of triacylglycerol-glycerol from glucose. The ability of trout intestines to metabolise fatty alcohol to triacylglycerols was the same in fish fed wax esters as in those fed triacylglycerols.

The desaturation and elongation of linolenic acid and eicosapentaenoic acid by hepatocytes and liver microsomes from rainbow trout (Oncorhynchus mykiss) fed diets containing fish oil or olive oil.

The products of desaturation and elongation of [1-14C]18:3(n - 3) and [1-14C]20:5(n - 3) were studied using hepatocytes and microsomes prepared from livers of trout maintained on diets containing either olive oil or fish oil, to establish the extent to which the formation of 22:6(n - 3) was enhanced in the absence of dietary 22:6(n - 3) and to investigate the pathway(s) of conversion of 18:3(n - 3) and 20:5(n - 3) to 22:6(n - 3). Levels of 20:5(n - 3) and 22:6(n - 3) in the total lipid of hepatocytes from trout fed olive oil were 20-fold and 10-fold, respectively, lower than in cells from trout fed fish oil. For both dietary groups, [1-14C]18:3(n - 3) was incorporated into hepatocyte lipid to a greater extent than [1-14C] 20:5(n - 3). Almost 70% of the total radioactivity from [1-14C]18:3(n - 3) was recovered in hepatocyte triacylglycerols, whereas radioactivity from [1-14C]20:5(n - 3) was recovered almost equally in neutral lipids (52%) and polar lipids (48%). The products of desaturation and elongation from both labelled substrates were esterified mainly into hepatocyte polar lipids, whereas elongation products of [1-14C]18:3(n - 3) were preferentially incorporated into neutral lipids. Radioactivity recovered in the 22:6(n - 3) of polar lipids of hepatocytes from trout fed olive oil, from both 14C substrates, was approximately double that in hepatocytes from trout fed fish oil. No radioactivity from either [1-14C]18:3(n - 3) or [1-14C]20:5(n - 3) was incorporated into 22:6(n - 3) by microsomes isolated from livers from either group of fish and incubated in the presence of acetyl-CoA, malonyl-CoA, NADH, NADPH, ATP and coenzyme A. However, significant radioactivity was recovered in 24:5(n - 3) and 24:6(n - 3) from [1-14C]20:5(n - 3) and more radioactive 24:6(n - 3) accumulated in microsomes from trout fed olive oil than from trout fed fish oil. The results establish that the formation of 22:6(n - 3) from both 18:3(n - 3) and 20:5(n - 3) in hepatocytes of rainbow trout is stimulated by omitting 22:6(n - 3) from the diet and are consistent with the biosynthesis of 22:6(n - 3) in trout liver cells proceeding via 24:5(n - 3) and 24:6(n - 3) intermediates.