Potential biological control of Erwinia tracheiphila by internal alimentary canal interactions in Acalymma vittatum with Pseudomonas fluorescens.

AIMS: We aim to determine if Pseudomonas fluorescens is a viable biological control for Erwinia tracheiphila within the insect vector, Acalymma vittatum. METHODS AND RESULTS: Pseudomonas fluorescens secreted fluorescein and inhibited growth of E. tracheiphila in disc diffusion assays. To determine if this antagonism was conserved within the insect vector, we performed in vivo assays by orally injecting beetles with bacterial treatments and fluorescent in situ hybridization to determine bacterial presence within the alimentary canal. CONCLUSIONS: Pseudomonas fluorescens inhibited the growth of E. tracheiphila on a nutrient-limiting medium. In situ experiments demonstrated that P. fluorescens is maintained within the alimentary canal of the beetle for at least 4 days, and co-occurred with E. tracheiphila. When beetles were first presented with Pseudomonas and then challenged with E. tracheiphila, E. tracheiphila was not recovered via FISH after 4 days. These data suggest that P. fluorescens has potential as a biological control agent to limit E. tracheiphila within the insect vector. SIGNIFICANCE AND IMPACT OF THE STUDY: This is a novel approach for controlling E. tracheiphila that has the potential to decrease reliance on insecticides, providing a safer environment for pollinators and growers.

Pattern of upper limb amputation associated with lower limb amputation: the UK military experience from Iraq and Afghanistan.

INTRODUCTION: The conflicts in Iraq and Afghanistan resulted in large numbers of personnel sustaining extremity injuries. In the context of polytrauma, partial hand amputation is often unrecorded. The aim of this work was to quantify the burden of upper limb (UL) amputation at any level occurring concurrently with a major (ankle and proximal) lower limb (LL) amputation. Knowledge of this cohort could aid in prosthetic modification to further improve quality of life outcomes in a population with dexterity loss. METHOD: A trauma database search was undertaken for all UK military LL amputees from the conflicts in Iraq and Afghanistan. A manual search method was employed to identify from the major LL amputees those who had a concurrent UL amputation at any level (including isolated finger amputation). Demographics, level of amputation, and injury profile data were recorded. RESULTS: Sixty-eight individuals were identified; the most prevalent population was bilateral LL with a unilateral UL amputation (60%). Most UL amputations were partial hand (75%). The was no statistically significant difference between left or right side (p=0.13). On the left side, correlation was found between amputation of the thumb and third digit (rho=0.34; p=0.005) not seen on the right. CONCLUSION: We have determined the rate of UL amputation at any level, in combination with LL amputation as a result of blast injury. Knowledge of these combinations enables further research to support anecdotal evidence that there is a need for tailored prosthetics in the context of potential dexterity loss making donning and doffing problematic.

Receptor-receptor interactions within receptor mosaics. Impact on neuropsychopharmacology.

Future therapies for diseases associated with altered dopaminergic signaling, including Parkinson's disease, schizophrenia and drug addiction or drug dependence may substantially build on the existence of intramembrane receptor-receptor interactions within dopamine receptor containing receptor mosaics (RM; dimeric or high-order receptor oligomers) where it is believed that the dopamine D(2) receptor may operate as the 'hub receptor' within these complexes. The constitutive adenosine A(2A)/dopamine D(2) RM, located in the dorsal striato-pallidal GABA neurons, are of particular interest in view of the demonstrated antagonistic A(2A)/D(2) interaction within these heteromers; an interaction that led to the suggestion and later demonstration that A(2A) antagonists could be used as novel anti-Parkinsonian drugs. Based on the likely existence of A(2A)/D(2)/mGluR5 RM located both extrasynaptically on striato-pallidal GABA neurons and on cortico-striatal glutamate terminals, multiple receptor-receptor interactions within this RM involving synergism between A(2A)/mGluR5 to counteract D(2) signaling, has led to the proposal of using combined mGluR5 and A(2A) antagonists as a future anti-Parkinsonian treatment. Based on the same RM in the ventral striato-pallidal GABA pathways, novel strategies for the treatment of schizophrenia, building on the idea that A(2A) agonists and/or mGluR5 agonists will help reduce the increased dopaminergic signaling associated with this disease, have been suggested. Such treatment may ensure the proper glutamatergic drive from the mediodorsal thalamic nucleus to the prefrontal cortex, one which is believed to be reduced in schizophrenia due to a dominance of D(2)-like signaling in the ventral striatum. Recently, A(2A) receptors also have been shown to counteract the locomotor and sensitizing actions of cocaine and increases in A(2A) receptors have also been observed in the nucleus accumbens after extended cocaine self-administration, probably representing a compensatory up-regulation to counteract the cocaine-induced increases in dopamine D(2) and D(3) signaling. Therefore, A(2A) agonists, through antagonizing D(2) and D(3) signaling within A(2A)/D(2) and A(2A)/D(3) RM heteromers in the nucleus accumbens, may be found useful as a treatment for cocaine dependence. Furthermore, antagonistic cannabinoid CB(1)/D(2) interactions requiring A(2A) receptors have also been discovered and possibly operate in CB(1)/D(2)/A(2A) RM located principally on striatal glutamate terminals but also on some ventral striato-pallidal GABA neurons, thereby opening up a new mechanism for the integration of endocannabinoid, DA and adenosine mediated signals. Thus, A(2A), mGluR5 and/or CB(1) receptors can form integrative units with D(2) receptors within RM displaying different compositions, topography and localization. Also galaninR/5-HT(1A) RM probably participates in the transmission of the ascending 5-hydroxytryptamine neurons, where galanin receptors antagonize 5-HT(1A) recognition and signaling. Subtype specific galanin receptor antagonists may therefore represent novel antidepressant drugs. These results suggest the importance of a complete understanding of the function of these RM with regard to disease. Ultimately receptor-receptor interactions within RM that modify dopaminergic and serotonergic signaling may give new strategies for treatment of a wide range of diseases associated with altered dopaminergic and serotonergic signaling.

Short-acting cocaine and long-acting GBR-12909 both elicit rapid dopamine uptake inhibition following intravenous delivery.

The rewarding effects of cocaine have been reported to occur within seconds of administration. Extensive evidence suggests that these actions involve the ability of cocaine to inhibit the dopamine (DA) transporter. We recently showed that 1.5 mg/kg i.v. cocaine inhibits DA uptake within 5 s. Despite this evidence, there remains a lack of consensus regarding how quickly i.v. cocaine and other DA uptake inhibitors elicit DA uptake inhibition. The current studies sought to better characterize the onset of cocaine-induced DA uptake inhibition and to compare these effects to those obtained with the high-affinity, long-acting DA transporter inhibitor, GBR-12909 (1-(2-bis(4-fluorphenyl)-methoxy)-ethyl)-4-(3-phenyl-propyl)piperazine). Using in vivo fast scan cyclic voltammetry, we showed that i.v. cocaine (0.75, 1.5, and 3.0 mg/kg) significantly inhibited DA uptake in the nucleus accumbens of anesthetized rats within 5 s. DA uptake inhibition peaked at 30 s and returned to baseline levels in approximately 1 h. The effects of cocaine were dose-dependent, with the 3.0 mg/kg dose producing greater uptake inhibition at the early time points and exhibiting a longer latency to return to baseline. Further, the blood-brain barrier impermeant cocaine-methiodide had no effect on DA uptake or peak height, indicating that the generalized peripheral effects of cocaine do not contribute to the CNS alterations measured here. Finally, we show that GBR-12909 (0.75, 1.5, and 3.0 mg/kg) also significantly inhibited DA uptake within 5 s post-injection, although the peak effect and return to baseline were markedly delayed compared with cocaine, particularly at the highest dose. Combined, these observations indicate that the central effects of dopamine uptake inhibitors occur extremely rapidly following i.v. drug delivery.

Effects of baclofen on operant performance for food pellets and vegetable shortening after a history of binge-type behavior in non-food deprived rats.

Operant performance of non-food deprived rats (n=8) was assessed under progressive ratio (PR) and concurrent PR-fixed ratio schedules of food pellet and/or vegetable shortening reinforcement. Post operant baselines, rats were matched and divided into 2 groups based upon the schedule of shortening availability: High restriction binge group (H, 1-hr home cage shortening access each week on Monday, Wednesday, and Friday) and Low restriction (L, 1-hr shortening access daily). Chow and water were continuously available; only access to the shortening was restricted. After 8 weeks, operant performance was reassessed. Lever pressing for shortening increased in the H rats for all schedules, but was either unaffected or decreased in the L rats. Pellet responding under the concurrent schedules increased for both groups. The effects of four dosages of (R)-baclofen (0.3-1.8 mg/kg, i.p.) on operant performance were also assessed. For both groups, 1.0 mg/kg baclofen significantly reduced shortening responding relative to saline for all schedules except one, but had no or minimal effect on pellet responding. This suggests a specific effect of baclofen on responding maintained by fat. These results indicate that intermittent episodes of bingeing on fat can increase the reinforcing efficacy of fat and that GABAB receptor activation can attenuate this effect.

Finite-time collapse of N classical fields described by coupled nonlinear Schrödinger equations.

We prove the finite-time collapse of a system of N classical fields, which are described by N coupled nonlinear Schrödinger equations. We derive the conditions under which all of the fields experiences this finite-time collapse. Finally, for two-dimensional systems, we derive constraints on the number of particles associated with each field that are necessary to prevent collapse.

Horticultural Production Systems Influence Ground Beetle (Coleoptera: Carabidae) Distribution and Diversity in Cucurbits.

Commercial cucurbit production typically involves agriculturally intensive practices, with fields prepared using conventional tillage, plasticulture, and chemically based pest management. Conservation-based management options are limited. In this study, we consider two alternative strategies, strip tillage and the use of row covers. We compare their impact on the beneficial carabid beetle (Coleoptera: Carabidae) community in melons and squash, following conventional or organic systems, over two years. Multivariate analysis demonstrated that soil management system (strip tillage versus plasticulture) was the primary variable influencing carabid distribution; row cover was a less important factor. The response to soil management was species dependent. Some dominant species, such as Harpalus pensylvanicus DeGeer, demonstrated no preference for a particular soil treatment. For others, including the tiger beetle, Cicindela punctulata Olivier, and a slug predator, Chlaenius tricolor Dejean, activity-density was higher in strip-tillage production systems. Our analysis suggested that strip-tillage production systems support a richer, more diverse carabid community. These results demonstrate that even within intensive annual horticultural systems, production practices can play a critical role in shaping the beneficial arthropod community, potentially encouraging or limiting ecosystem services.

Platelet activating factor receptor expression is associated with neuronal apoptosis in an in vivo model of excitotoxicity.

Platelet activating factor (PAF), an endogenous proinflammatory agent, mediates neuronal survival, glutamate release, and transcriptional activation following excitotoxin challenge. To determine whether PAF receptor (PAFR) expression is altered during excitotoxicity, changes in PAFR mRNA localization were compared with markers of neuronal apoptosis and reactive gliosis following systemic injection of kainic acid. Data from semi-quantitative RT-PCR, in situ hybridization, DNA fragmentation, cellular morphology analysis, and immunohistochemistry demonstrate that the localization of PAFR mRNA is altered during kainic acid-induced neurodegeneration. While PAFR mRNA is normally exhibited by neurons and microglia in rat hippocampus, expression becomes restricted to apoptotic neurons and to glia involved in phagocytosing apoptotic debris following treatment with excitotoxin. PAFR mRNA is rarely detected in surviving neurons. These data provide the first indication that PAFR-expressing neurons may be preferentially susceptible to excitotoxic challenge.

The effectiveness of nutrition counselling by Australian General Practitioners.

OBJECTIVE: To determine whether General Practitioners (GPs) consider or provide nutrition counselling for hypertension, diabetes, lipid disorders, ischaemic heart disease (IHD), overweight or obesity, and whether GPs include assessment of the patient's usual diet, assessment of the patient's readiness to change their diet, provision and discussion of nutrition leaflets when counselling. DESIGN: A self-completed questionnaire. SETTING: New South Wales, Australia. SUBJECTS: A total of 399 GPs were surveyed using a division mailing list. METHODS: Questionnaires were distributed in May 2004 with two reminders provided at four-weekly intervals. RESULTS: Of the 399 GPs, 28 no longer practiced at the address while nine were on extended leave. Of the remaining 362, 50% responded, 5% declining to participate, while 163 (45%) completed the questionnaire. GPs were less likely to strongly agree to consider nutrition for hypertension (37%), IHD (61%) and overweight (68%), than diabetes (86%), lipid disorders (82%) and obesity (83%). They were also less likely to strongly agree to provide nutrition for hypertension (22%), IHD (46%) and overweight (45%), than diabetes (79%), lipid disorders (71%) and obesity (68%). In total, 97% of GPs provided some nutrition counselling, with 66% 'often' assessing the patients diet and 59% 'often' assessing the patient's readiness to change their diet. In total, 45% were unaware of stage of change behaviour theory. A total of 85% used nutrition leaflets and 59% 'often' discussed these with their patients. CONCLUSIONS: Determining what are the barriers to nutrition counselling for hypertension, IHD and overweight is urgently needed. Educating GPs on stage of change behaviour theory could increase the efficacy of the counselling provided.

Low-glycemic index foods improve long-term glycemic control in NIDDM.

OBJECTIVE: To compare high- and low-glycemic index (GI) diets in the treatment of non-insulin-dependent diabetes mellitus (NIDDM). RESEARCH DESIGN AND METHODS: Sixteen subjects with well-controlled NIDDM and normal lipid profile, 10 of whom continued oral hypoglycemic medication, participated in the study. A diet that emphasized low-GI foods (e.g., porridge, pasta) was compared with a high-GI diet (e.g., processed cereals, potatoes). The GI of the low-GI diet was 15% lower than the high-GI diet (77 +/- 3 vs. 91 +/- 1) but otherwise similar in macronutrient composition and fiber, as determined by a 4-day weighed record. The diets were instituted under instruction from a dietitian who visited subjects at home on a weekly basis. Body weight was maintained within 1-2 kg. RESULTS: Glycemic control was improved on the low-GI diet compared with the high-GI diet (statistically significant findings, P less than 0.05). Mean glycosylated hemoglobin at the end of the low-GI diet was 11% lower (7.0 +/- 0.3%) than at the end of the high-GI diet (7.9 +/- 0.5%), and the 8-h plasma glucose profile was lower (area under the curve above fasting 128 +/- 23 vs. 148 +/- 22 mmol.h-1.L-1, respectively). Mean fasting plasma glucose, total cholesterol triglycerides, and lipoproteins did not show important differences. CONCLUSIONS: A low-GI diet gives a modest improvement in long-term glycemic control but not plasma lipids in normolipidemic well-controlled subjects with NIDDM.

Persistent changes in the fatty acid composition of erythrocyte membranes after moderate intake of n-3 polyunsaturated fatty acids: study design implications.

To examine the incorporation of n-3 polyunsaturated fatty acids (PUFAs) into erythrocyte membranes during and after moderate n-3 PUFA intake, 12 healthy men were fed three diets for 6-wk periods in a 3 x 3 crossover design, supplying different amounts of eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3): a control diet, a fish diet (0.15 g EPA/d, 0.41 g DHA/d), and a fish + oil diet (5 g fish oil/d; 0.99 g EPA/d and 0.99 g DHA/d). A 6-wk washout period was allowed between diets. Between 6 and 12 wk after the fish + oil diet, erythrocyte EPA and DHA were still declining and it was only after 18 wk that erythrocyte EPA had returned to baseline whereas DHA had not. Investigators examining variables that are influenced by altered membrane fatty acid composition should be aware of these prolonged effects when designing studies. Protracted washout periods (greater than 18 wk) make the classic crossover design prohibitive and a parallel design becomes essential.

A mixed Australian fish diet and fish-oil supplementation: impact on the plasma lipid profile of healthy men.

Twelve healthy men were fed in turn three diets for 6 wk each in a 3 x 3 randomized block design: a control diet (essentially fish free), a fish diet (200 g lean Australian fish flesh/d), and the same fish-based meal but supplemented with 5 g fish oil/d. Dietary eicosapentaenoic acid [EPA, 20: 5n-3 (omega-3)] was strongly associated with erythrocyte membrane EPA (r = 0.908 at 6 wk), strengthening its value as a measure of compliance in fish and fish-oil feeding trials. On the fish diet, subjects had increased incorporation of n-3 polyunsaturated fatty acids (PUFAs) at the expense of n-6 PUFAs in their erythrocyte membranes. When the fish-based diet was supplemented with fish oil (5 g/d), there was a significant lowering of plasma triacylglycerol (-0.16 +/- 0.24 mmol/L; mean +/- SD). No change in plasma total cholesterol was detected although the fish + oil diet produced a reduction in very-low-density-lipoprotein cholesterol (-0.24 +/- 0.26 mmol/L).

Dietary treatment of iron deficiency in women of childbearing age.

BACKGROUND: The Australian Iron Status Advisory Panel advocates dietary intervention as the first treatment option for mild iron deficiency [serum ferritin (SF) = 10-15 microg/L]. However, there appear to be no studies on the efficacy of dietary treatment for iron deficiency. OBJECTIVE: We compared the effects of iron supplementation and of a high-iron diet on serum ferritin (SF) and hemoglobin in iron-deficient women of childbearing age. DESIGN: Forty-four iron-deficient women (SF <15 microg/L or SF = 15-20 microg/L plus serum iron <10 micromol/L and total-iron-binding capacity >68 micromol/L) and 22 iron-replete women (hemoglobin > or =120 g/L and SF >20 microg/L) matched for age and parity categories were enrolled and completed 7-d weighed food records at baseline. The iron-deficient women were randomly allocated to receive iron supplementation (105 mg/d; supplement group) or a high-iron diet (recommended intake of absorbable iron: 2.25 mg/d; diet group) for 12 wk. Hematologic and dietary assessments were repeated at the end of the intervention and again after a 6-mo follow-up. RESULTS: Mean SF in the supplement group increased from 9.0 +/- 3.9 microg/L at baseline to 24.8 +/- 10.0 microg/L after the intervention and remained stable during follow-up (24.2 +/- 9.8 microg/L), whereas the diet group had smaller increases during the intervention (8.9 +/- 3.1 to 11.0 +/- 5.9 microg/L) but continued to improve during follow-up (to 15.2 +/- 9.5 microg/L). Mean hemoglobin tended to improve in both intervention groups, but the change was only significant in the supplement group. CONCLUSIONS: In iron-deficient women of childbearing age, a high-iron diet produced smaller increases in SF than did iron supplementation but resulted in continued improvements in iron status during a 6-mo. follow-up.

Resting energy expenditure in children with phenylketonuria.

Reports have suggested that children with phenylketonuria (PKU) weigh more compared with reference data. We found lower body protein and bone mineral density in children with PKU. These children may have a predisposition becoming overweight because of an alteration in body composition, which may lower resting energy expenditure (REE). REE was measured in 30 (15 males, 15 females) children with PKU (aged 9.6 +/- 2.9 y) and in 65 (23 males, 42 females) control children (aged 11.2 +/- 3.1 y). There was a comparable range in body fat within each group (control group: 11-34%; PKU group: 10-34%). The mean REE was similar between the male and female children with PKU (5300 +/- 757 and 4703 +/- 1024 kJ/24 h, respectively) and the control subjects (5306 +/- 969 and 5164 +/- 701 kJ/24 h, respectively). The children with PKU had an REE similar to that predicted from control data (males 102.1 +/- 7.8% of predicted and females 100.2 +/- 8.5% of predicted). This study found no evidence of a reduced REE or of increased weight in children with PKU.

Hypocholesterolemic effect of substituting soybean protein for animal protein in the diet of healthy young women.

The effect of dietary protein on the level of plasma cholesterol in young, healthy, normolipidemic women was investigated in two separate studies by feeding either a conventional diet containing mixed protein, or a plant protein diet in which the animal protein of the first diet was replaced by soy protein meat analogues and soy milk. The diets were similar with respect to carbohydrate, fat and sterol composition. The first study, lasting 73 days and involving six subjects, gave an indication that plasma cholesterol levels were lower on the plant protein diet. The second study, which incorporated a number of improvements based on experience, lasted 78 days and used a cross-over design involving two groups of five subjects each. In this study, the mean plasma cholesterol level was found to be significantly lower on the plant protein diet.

Decreased bone mineral density in children with phenylketonuria.

Previous studies have suggested that children with phenylketonuria (PKU) have a reduction in bone mineralization compared with control subjects. To investigate this, bone mineral density (BMD) of the total body (TBMD) was measured in 32 prepubertal children with PKU and in 95 age-matched control subjects. Spine bone mineral density (SBMD) was also recorded in a subset, 24 with PKU and 55 control subjects. The effect of dietary intake on bone mass was assessed in 30 of the children with PKU and in 12 control subjects. In the children with PKU, TBMD and SBMD were significantly lower than in the control subjects after adjustment for height and weight (P = 0.03 and P = 0.003, respectively). The children with PKU had a higher intake of calcium (P < 0.0001), phosphorus (P = -0.0002), and magnesium (P < 0.0001), suggesting that their lower BMD occurred despite an adequate diet based on current recommendations. Further study is needed to establish the cause of this deficit in bone mass and the benefit of additional nutritional support to reverse this problem.

Effects of cocaine self-administration on food-reinforced responding using a discrete trial procedure in rats.

Cocaine addiction has been characterized by a shift from controlled to uncontrolled and compulsive drug use. Using novel self-administration procedures, we attempted to model this transitional phase and characterize the behavioral changes that underlie it. We chose to use food-reinforced responding across the light/dark cycle as an indicator of the degree to which cocaine was disrupting ongoing behavior as a potential measure of dysregulation. Four groups of rats (n=5-6) were given 24-h access to cocaine (1.5 mg/kg/inj) available in 2, 3, 4, or 5 discrete trials/h. All rats were given continuous access to a second lever that resulted in the delivery of a 45 mg food pellet under a fixed ratio 1 schedule. The results showed that under low access conditions (eg 2 discrete trials/h), both food- and cocaine-reinforced responding were diurnally regulated and occurred coincidentally. As access to cocaine was increased, there was a progressive disruption in the diurnal control over both food- and cocaine-maintained responding. High access conditions also produced transient decreases in the total levels of food-reinforced responding. These findings suggest that high access to cocaine under the discrete trial cocaine self-administration procedure produces a transient disruption in the diurnal control over behavior maintained by food and that the level of control (or loss of) may be a useful marker of dysregulation.

Baclofen attenuates the reinforcing effects of cocaine in rats.

The effect of the GABAB agonist baclofen on cocaine self-administration in the rat was investigated. In the first experiment, rats trained to self-administer i.v. cocaine (1.5 mg/kg/inj) on a progressive ratio (PR) schedule were pretreated with various doses of baclofen (1.25, 2.5, or 5.0 mg/kg). Baclofen produced a dose-dependent decrease in the break points. In the second experiment, baclofen (2.5 mg/kg) was found to decrease significantly break points across a series of unit injection doses of cocaine (0.18, 0.37, 0.75, 1.5 mg/kg/inj). Baclofen produced only modest effects on food-reinforced responding even at the largest dose tested (5.0 mg/kg). These data suggest that baclofen may produce a specific attenuation of cocaine reinforcement. Baclofen produced no significant change in the rate of i.v. cocaine intake on a fixed ratio (FR 1) schedule. These data support a number of recent observations that rate of drug intake may be an insensitive measure of changes in the motivation to self-administer cocaine.

The effect of zinc supplements on lipoproteins and copper status.

As part of a study to determine the effect of 150 mg zinc/day on plasma lipoproteins, healthy young female (n = 26; mean age 27 years) and male (n = 21; mean age 28 years) volunteers took part in a double-blind cross-over trial lasting 12 weeks. During 6 weeks of supplementation, plasma Zn rose significantly in both groups, indicating compliance. Plasma total cholesterol remained unchanged in both males and females. However, mean LDL-cholesterol decreased from 2.38 to 2.17 mmol/l in females and there was a trend for total HDL-cholesterol to be redistributed in that HDL2 rose and HDL3 fell slightly. In parallel with these changes in females, Zn supplements reduced the ferroxidase activity of serum caeruloplasmin (from 13.0 to 11.3 U/ml) and the antioxidant activity of erythrocyte superoxide dismutase (E-SOD) (from 4557 to 3638 U/g Hb) and CuZn E-SOD (from 2184 to 1672 U/g Hb). Plasma Cu and haematocrit were unaffected. No such changes were seen in males in either lipoproteins or these indicators of Cu status. Since the females were lighter than the males but received the same dose, a dose-response effect rather than a sex difference cannot be ruled out. Overall, Zn supplements significantly decrease a major risk factor for CHD in females but reduced their Cu status.

Chylomicron metabolism in rabbits fed diets with or without added cholesterol.

Intestinal lymph chylomicrons, isotopically labelled with radioactive triacylglycerol and cholesterol, were injected into normally fed and cholesterol-fed rabbits in order to establish the pattern of clearance of intestinal lipoproteins from the plasma. In normal rabbits the cholesterol moiety of chylomicrons was removed from the plasma less readily than triacylglycerol. In cholesterol-fed rabbits, the clearance of triacylglycerol was unaltered, but clearance of chylomicron cholesterol was further retarded. The majority of the injected lymph cholesterol was recovered in d less than 1.019 g/ml lipoproteins. These observations support the notions that clearance of chylomicron remnants is impaired in the rabbit, and that hypercholesterolaemia in the cholesterol-fed rabbit is due to an accumulation of chylomicron remnants in the plasma.