In vitro effect of cyclosporin A on primary and chronic BK polyoma virus infection in Vero E6 cells.

Cyclosporin A (CsA) is known to possess antiviral activity against several viruses in vitro, but the effect of CsA on BK polyoma virus (BKV) replication has not been examined. We investigated the impact of CsA on primary, chronic, and high-level BKV infection using a cell system of kidney cell origin (Vero E6 cells). During the first 2 h post infection, cells treated with CsA up to 3200 microg/L showed a near-identical BK viral load to untreated cells, with only a very minor reduction in the CsA-treated cells observed at 4 h. In chronic culture, CsA completely suppressed the primary BKV infection peak in a non-dose-dependent manner within the dose range of 200-12,800 microg/L (P<0.05). BKV reactivation was also inhibited in the presence of CsA at doses of 200-3200 microg/L: the mean number of BKV DNA copies/mL remained stable or even decreased slightly compared with a 7-log increase in the non-CsA group (P<0.01). CsA did not influence BKV DNA copies/mL in Vero E6 cells with high-level infection (>10(9) copies/mL). Cellular protein measurements indicated that the antiviral effect of CsA was not a result of cytotoxicity. These findings from a relevant in vitro kidney cell system indicate that CsA suppresses the primary BKV infection peak and inhibits escape to BKV reactivation; these effects are dose independent and not related to cytotoxicity. The intracellular antiviral mode of action of CsA against BKV does not appear to be via inhibition of viral cell entry pathways.

Carnitine, acylcarnitine and amino acid profiles analyzed by tandem mass spectrometry in a surfactant/virus mouse model of acute hepatic encephalopathy.

Tandem mass spectrometry (MS/MS) was used to analyze multiple serum metabolites for the first time in a surfactant/virus mouse model of acute hepatic encephalopathy (AHE). AHE is characterized by acute liver failure that can lead to potentially lethal increases in intracranial pressure. We have reproduced AHE in young CD-1 mice exposed from postnatal day (P) 2-13 to the industrial surfactant, Toximul 3409F (Tox), and then infected intranasally on P14 with sublethal doses (LD(10-30)) of mouse-adapted human influenza B (Lee) virus (FluB). The sera analyzed by MS/MS were from mice exhibiting typical markers of Tox-mediated potentiation of viral illness, including reduced weights and blood glucose levels. Most metabolite abnormalities were not evident until five days after viral infection (P19), the time corresponding to the onset of weight loss and mortality. Values for fatty acylcarnitines and amino acids in the Tox+FluB-treated mice were either additive or supra-additive relative to the effects of either treatment alone. Amino acid profiles were consistent with those reported for human AHE. None of the treated mice exhibited signs of carnitine deficiency, and propionylcarnitine levels were normal. On P19, mice given combined Tox+FluB treatment had significant increases in levels of both medium- and long-chain acylcarnitines (C6:0-C12:0 and C14:0-C20:0, respectively), including their monounsaturated metabolites. Levels of medium-chain dicarboxylic and long-chain hydroxy-acylcarnitines were also elevated in the combined treatment group. The results of this study indicate a diffuse mitochondrial dysfunction in Tox+FluB-treated mice that results in a serum metabolite profile unique from those observed in classic inherited metabolic disorders.

Utilization of vero cells for primary and chronic BK virus infection.

BK virus (BKV) nephropathy has a poor prognosis for renal allograft survival with 30% to 60% risk of allograft loss over 1 year. In the past decade, BKV nephropathy has occurred in 1% to 10% of renal transplant patients, with higher rates observed in patients with increased immunosuppression exposure and renal allograft injury. Vero cells (Green monkey kidney cell origin) were optimized for BKV primary and chronic infection inclusive of culture requirements for 60-day growth and monolayer confluence. Quantification of BKV replication in the culture supernatant (SN) and cells was by real-time polymerase-chain reaction (PCR) using the Roche Lightcycler 2.0. Primary BKV infection of Vero cells is achieved by 2 hour incubation with 6.5 x 10(5) BKV copies with subsequent washing of cells leading to steady-state cellular infection of 10(2) to 10(3) BKV copies. Primary infection is demonstrated within 7 to 10 days by a >10-fold increase of BKV copies in SN. Thereafter, a BKV viral load reduction in SN to a chronic/latent level (<10(2) BKV copies in SN) is observed by 14 days. Vero cells with chronic low-level BKV infection (10(2)-10(3) BKV copies in cells) exhibited reactivation (>10(5) BKV copies in SN) in >72% of late culture wells after 40 days. Vero cells can accommodate primary and chronic BKV infection followed by viral reactivation in late culture. The performance characteristics of 3 different pathogenic BKV strains obtained from patients with BKV nephropathy had infectivity profiles that correlated well the relative clinical profile in this Vero cell culture system.

Evaluation of performance factors affecting two formulations of cyclosporine in pediatric renal transplant patients.

Success of renal transplantation in children is largely due to improvements in immunosuppressant therapy since the introduction of calcineurin inhibitors. The aim of this study was to identify possible factors that result in formulation differences in the exposure of pediatric patients to cyclosporine (CsA). We examined the handling of the two major formulations of CsA in a group of pediatric renal transplant recipients. The pharmacokinetic profiles of both formulations were assessed, and the data stratified to assess the effects of age, gender, time posttransplant, and other concomitant drug therapy on the two CsA formulations. The microemulsified formulation (MEC) enhanced bioavailability compared to the older oil-based formulation (CYA), especially at C2, with more predictable and consistent absorption in children. This higher bioavailability allowed a 15% reduction of dosing to achieve equal drug exposure. The concentration achieved by MEC at C2 demonstrated a much higher correlation with area under the concentration curve (AUC) than the concentration at C0. In the case of CYA a strong correlation was obtained between AUC and the concentrations obtained at both C0 and C2. Calcium channel blockers increased AUC(0-8) for both CsA formulations. Norfloxacin and pravastatin cotreatment had no effect on either of the CsA formulations. In contrast, the bioavailability of CsA was increased in boys using MEC formulation but this gender-based difference was absent during the use of CYA. This suggests that caution is required for introduction of new formulations of drugs to pediatric patients to evaluate differential effects of age, gender, and concomitant drug therapy.

Two formulations of the industrial surfactant, Toximul, differentially reduce mouse weight gain and hepatic glycogen in vivo during early development: effects of exposure to Influenza B Virus.

Previous studies demonstrated that young mice exposed chronically to industrial surfactant (IS) do not exhibit obvious adverse health effects, but do have persistently reduced body weights and compromised hepatic energy metabolism. The present study examined the time course of effects of two formulations of the Toximul (Tox) class of anionic/nonionic IS on body weights and liver glycogen (+/-virus) during early development. Results showed that effects differed in two commonly used strains of mice. In CFW mice, 12 days' exposure to Tox resulted in retardation of weight gain that was most obvious several days after exposure ceased. In this strain effects were greater with Tox 3409F than with Tox MP-A and appeared to be reversible except when the mice were treated with both Tox 3409F and FluB. Weights of the CD-1 mice were not affected by either Tox treatment alone, but were significantly reduced on postnatal day 20 when Tox exposure had been combined with FluB infection. Postnatal replenishment of hepatic glycogen stores during the first three weeks also occurred at different rates in CFW and CD-1 mice. The effects of Tox (+/-FluB) on glycogen also varied with mouse strain and Tox formulation. In CFW mice, exposure to either formulation resulted in significant (55-59%) reductions in glycogen, although reductions were not evident until nine days after Tox exposure stopped. By contrast, hepatic glycogen in CD-1 mice was reduced both during and after dermal exposure to Tox 3409F, whereas no effect was observed with Tox MP-A. Notably, the 3409F effect was reversible in the CD-1 mice, but reversal did not occur in mice also infected with FluB. Tox MP-A+FluB-treated mice exhibited only a transient glycogen reduction. These results illustrate the importance of mouse strain and formulation specificities in assessing biological effects of xenobiotic surfactants. As well, they emphasize that chronic IS exposure can induce changes in growth and energy substrate availability in young mice that may not be evident unless there is a precipitating cofactor such as a viral infection.

Third dose of basiliximab in pediatric renal transplantation.

Antibody induction therapy is frequently used in pediatric renal transplantation to reduce risk of early rejection. We previously reported lower rates of human herpes virus type 6 (HHV-6) reactivation in patients receiving monoclonal antibody induction with basiliximab, compared to patients receiving antithymocyte globulin/antilymphocyte globulin treatment. Subclinical rejection events were still present in many patients in the first 6 months after transplantation. This prompted a third dose of basiliximab to be administered at day 21 in addition to the standard two doses given immediately prior to transplantation and on day 4. No significant reduction of subclinical rejections was noted in the 11 patients receiving triple dosing of basiliximab. Two patients developed an allergic reaction responsive to intravenous fluids, steroids, and antihistamines with full resolution within 30 minutes of administration. There was no increase in de novo infection or reactivation of HHV-6 or Epstein-Barr virus in this group compared to patients receiving two doses of basiliximab. The goal of reduction of early subclinical rejection events was not achieved with the third dosing of basiliximab in this initial group of pediatric renal transplant patients. However, 63.6% of patients receiving triple basiliximab remained free of clinical and/or subclinical rejection for the first 6 months posttransplant compared to only 36.4% remaining rejection-free for the same interval in the group who received the conventional two doses of basiliximab.

Simulect and HHV-6 in pediatric renal transplantation.

Herpes virus reactivation is of increasing interest as we aim to decrease morbidity and mortality in the pediatric renal transplant population. We previously reported increased reactivation of HHV-6 and Epstein Barr virus (EBV) with anti-thymocyte globulin/ALG induction therapy. HHV-6 reactivation and de novo infection has been monitored in 31 consecutive pediatric renal transplant patients receiving antibody induction with Simulect. Human Herpes virus-6 (HHV-6) was correlated with EBV reactivation and de novo infection rates, allograft function at 1 year, donor source and number, and patient age and gender. One HHV-6 de novo infection was associated with an early grade II rejection that was steroid resistant but ATG/ALG responsive. Sixteen of 31 (54.8%) patients had HHV-6 reactivation during the first year and eight patients had a prior reactivation profile before transplant. Thirteen patients (41.9%) were naïve to EBV infection prior to transplant with evidence of primary infection in 11 of 13 patients between 6 weeks and 1 year posttransplant. EBV reactivation was noted in four patients with past immunity to EBV. IgM Ab to EBV or HHV-6 during the first year posttransplant did not correlate with risk of rejection during the first year or graft function one year posttransplant. The only patient with positive HHV-6 IgM Ab in the first posttransplant month was a de novo infection in a 2-year-old boy who was naïve for HHV-6 at the time of transplant. Simulect appears safe in pediatric renal transplant with low risk of HHV-6 or EBV infection in the first 1 to 2 months posttransplant.

Elevated anticardiolipin antibodies in acute liver failure.

Antibodies to cardiolipin (aCLA), a phospholipid primarily localized in inner mitochondrial membranes, were transiently elevated (P<0.01) when mice were exposed to an industrial surfactant and then infected with influenza B virus, a model of acute liver failure (ALF). Children with ALF also had elevated levels of aCLA.

Decreased bone mineral density in the pediatric renal transplant population.

All renal transplant recipients at our centre have had bone mineral density assessment (BMD) by DEXA scans of their lumbar spine while on the transplant waitlist and at 6-month intervals post-transplant over the past 7 yr. Risk factors for osteopenia and osteoporosis including donor source, dialysis status prior to transplantation, prior renal disease, and biopsy confirmed rejection events and their relationship to BMD of the lumbar spine were assessed. Thirty-nine children transplanted over the past 7 yr were included in this study. In total, 127 BMD longitudinal assessments were performed. From 1990 to 1997, ATG/ALG was used as antibody induction therapy. From 1997 to 2002, Basiliximab was utilized. Cyclosporin A (CyA) was the primary immunosuppressant for most children with tacrolimus as primary (n = 2) and switch for CyA failure or toxicity (n = 16). Prednisone was administered at a dose of 1 mg/kg/day for the first week and tapered to 10 mg/m2/alternate day by 1 month post-transplant. Azathioprine 1.5 mg/kg/day was continued for 1 yr and discontinued in children who were rejection free. All rejections were biopsy confirmed and treated with a prednisone pulse. Using a repeated measures regression analysis, we have found that L1-L4 BMD z score is affected by height and transplant number. It is also related to time relative to transplant in a quadratic fashion. There was an inverse relationship between advancing patient age and L1-L4 BMD z score. L1-L4 BMD z score was not related to weight, pre-existing renal disease, gender, donor source, type of renal replacement therapy prior to transplantation, or rejection events.

Extravesical ureteroneocystostomy with and without internalized ureteric stents in pediatric renal transplantation.

The use of ureteric double-J stents and the Lich-Gregoir (extravesical) technique of ureteroneocystotomy have both been shown to decrease the rate of urologic complications in adult kidney transplantation (Tx). There are, however, few studies of the systematic use of stents in pediatric renal Tx. Between 1991 and 1997, 32 consecutive pediatric renal transplant recipients routinely received a 6F-12 cm indwelling double-J stent and were studied prospectively. These patients were compared with 32 consecutive pediatric recipients in whom a stent was not used. The latter were transplanted between 1987 and 1991 and formed the control group. All patients had a Lich-Gregoir ureteroneocystotomy. Stents were removed under general-anesthetic cystoscopy 2 3 weeks after Tx. Immunosuppression for stented patients was polyclonal antibody induction, delayed (7-10 days) cyclosporin A, azathioprine, and prednisone. The control group received the same triple drug regimen but with no induction in 29 of the 32 patients. All patients were followed-up with at least one ultrasound evaluation in the first month, and a renal scan and repeat ultrasound were performed if there was any rise in serum creatinine. In the stented group there were two patients with urinary leak and no obstructions. In the non-stented group there were no leaks and one obstruction. There was no graft loss owing to urologic complications in either group. There were three cases of stent expulsion (all in girls) and one case of stent migration in the posterior urethra (a boy). The 1-yr graft survival rate was 90.6% in the stented group and 65.6% in the non-stented group. The prophylactic use of an indwelling ureteral stent in pediatric renal Tx did not reduce the risk of urinary leakage or obstruction. Stent migration is a common phenomenon and, while not a serious complication, is traumatic to children. Furthermore, removal of an internalized double-J stent requires a general anesthetic. We recommend using a stent for selected patients only.

Effects of antipyretics on mortality due to influenza B virus in a mouse model of Reye's syndrome.

OBJECTIVES: To determine the effects of acetylsalicylic acid (ASA) and acetaminophen on mortality due to influenza B infection in neonatal and weanling mice, as well as any synergistic, antagonistic or indifferent effects of the combined antipyretic and virus on mortality in mice pretreated with low doses of an industrial surfactant, Toximul MP8, which has been shown to reproduce many of the features of Reye's syndrome. In vitro studies were done to determine whether ASA or acetaminophen altered the normal, interferon-mediated antiviral responses of mammalian cells. The involvement of ASA or other commonly used xenobiotics in the induction of Reye's syndrome following virus illness has not been resolved; to do so, and to elucidate the underlying metabolic mechanism, requires these studies in an animal model. DESIGN: Prospective animal study. ANIMALS: Newborn (945) and weanling (840) Swiss white mice, divided into 12 subgroups. INTERVENTIONS: Some groups received Toximul MP8 before inoculation with a dose of mouse-adapted human influenza B that produces 30% mortality (LD30); after infection, each subgroup received either placebo, ASA or acetaminophen. Mortality counts were taken daily. The in vitro effects of the antipyretics on interferon response were determined using standard virology techniques. OUTCOME MEASURE: Mortality, analyzed by survival curves (log rank test) or cumulative daily mortality (chi 2 analysis). Plaque-reducing dose (PRD50) was used to determine the outcome of the in vitro analyses. RESULTS: In neonatal mice, only subgroups given combined treatment with acetaminophen and Toximul MP8 had a statistically significant higher mortality rate than with the mice given influenza B alone. In weanling mice, it appeared that ASA shortened the time until death; however, this difference was not statistically significant. In vitro studies demonstrated that both ASA and acetaminophen decreased the interferon-induced antiviral responses of cultured mammalian cells. CONCLUSION: Antipyretics have the potential to exacerbate the consequences of a viral infection, although the specific effects are subtle and appear to be age-related.

Kidney graft loss in children: implications for program development.

BACKGROUND: Graft survival in children who undergo kidney transplantation is lower than that in adults. The objective of the study was to review the experience of the first 22 years of operation of the regional pediatric kidney transplantation unit for Atlantic Canada, based at the IWK-Grace Health Centre, Halifax, and to use the results to improve graft survival. METHODS: All cases of kidney transplantation performed at the centre from 1971 to 1992 were reviewed and the data compiled with the use of a predetermined database outline. Data for first transplants were analysed and compared with those in North American databases. Of the 40 graft failures, 19 (48%) occurred within the first 3 months after transplantation, a rate similar to that at other centres. The overall survival rates tended to be slightly lower than those of international databases. The introduction of cyclosporine A as an immunosuppressant, in 1985, did not provide the expected marked improvement in survival. Infection frequently accompanied acute rejection, and there was a delay in treatment of infections and rejection after discharge home. On the basis of these preliminary findings, several program changes were made: 1) a sequential immunosuppression protocol was implemented, 2) the intensity of the medical surveillance was increased for the first 3 months after transplantation, with aggressive treatment of infections and rejections, 3) a dedicated pediatric transplantation team was established as a subset of the adult team and 4) pediatric-specific selection criteria for cadaver donors were formulated. After these changes were implemented, data were collected and analysed up to June 30, 1997. RESULTS: Graft survival rates at 1, 2 and 5 years improved dramatically. After the beginning of 1993, there were only 2 graft losses among 22 transplants. Only one of these occurred in the first 3 months, and it was due to recurrent disease. Twenty-four rejection episodes occurred (10 in the first 3 months after transplantation), but all were reversed easily with high-dose steroid therapy. INTERPRETATION: Sequential immunosuppression with close medical surveillance and early aggressive treatment of infection and rejection contribute to a marked improvement in kidney graft survival in children.

Central precocious puberty and chronic renal failure: a reversible condition post renal transplantation.

A 3 year-old boy with chronic renal failure associated with prune belly syndrome who developed central precocious puberty is described. He had been maintained on cyclic peritoneal dialysis from age 13 months with creatinine levels of 400-600 mumol/l. Increased linear growth rate probably began at 18 months, and by 38 months of age he had testicular enlargement and pubic hair consistent with Tanner stage 2. Elevated levels of serum testosterone (3.6 nmol/l; normal < 0.7 nmol/l) and luteinizing hormone (LH) (2.8 IU/l; normal < 1.0 IU/l) were demonstrated with a pubertal response to luteinizing hormone-releasing hormone (LHRH) stimulation (peak LH 43.5 IU/l). Other endocrine tests demonstrated hyperprolactinemia (170 micrograms/l; normal 3.4-22 micrograms/l), but normal pituitary-thyroid and pituitary-adrenal functions and normal cranial MR imaging. Despite LHRH-agonist therapy with leuprolide over the next 8 months, he showed an incomplete response with only partial inhibition of basal LH and testosterone levels, and continued significant increments in height standard deviation scores (Ht-SDS) and bone age estimates. However, the sexual precocity appeared fully reversible following a successful living-related renal transplant at age 50 months. Despite discontinuation of leuprolide treatment post-operatively, there was a full reversal of his serum LH and testosterone to a prepubertal profile as well as normalization of the serum prolactin levels. Whereas most boys with chronic renal failure show delayed pubertal development and suppressed linear growth, our patient presents a unique phenomenon of reversible central precocious puberty. The effects of leuprolide therapy in the presence of a uremic milieu and the outcome of successful renal transplantation on sexual precocity are described.

Sequestration of coenzyme A by the industrial surfactant, Toximul MP8. A possible role in the inhibition of fatty-acid beta-oxidation in a surfactant/influenza B virus mouse model for acute hepatic encephalopathy.

We have investigated the mechanistic basis of our recent observation that exposing young mice to an industrial surfactant potentiates the inhibition of fatty-acid beta-oxidation that occurs with subsequent virus infection (Murphy et al., Biochim. Biophys. Acta 1315, 208-216, 1996). In our mouse model for acute hepatic encephalopathy (AHE), neonatal mice were painted on their abdomens from birth to postnatal day 12 with nontoxic amounts of the industrial surfactant, Toximul MP8 (Tox), and then infected with a sublethal dose (LD30) of mouse-adapted human Influenza B (Lee) virus (FluB). Mortality in mice treated with Tox + FluB was significantly higher than that in mice treated with FluB alone. In vitro assays of hepatic beta-oxidation of [1-(14)C]palmitic and [1-(14)C]octanoic acids in the presence or absence of exogenous coenzyme A (CoA) indicated that Tox-mediated inhibition of oxidation was masked when CoA was added to the assays. FluB also inhibited beta-oxidation by 20-30%, however this effect was independent of exogenous CoA which suggested that it involved a different mechanism. Tox-mediated potentiation of the inhibitory effect was most obvious (> 80% inhibition) when assays were done without added CoA. Analysis of hepatic CoA and its esters indicated that levels of both free CoA and acetyl-CoA were significantly lower in mice that were painted with Tox for 12 days. Tox-dependent reductions of acetyl-CoA were transient and returned to normal values after cessation of painting, whereas those of CoA persisted. FluB infection alone significantly reduced hepatic acetyl-CoA and the magnitude of this reduction (> 30%) was not affected by pre-exposing the mice to Tox. Relative to control mice, levels of acid insoluble acyl-CoA esters were elevated significantly in FluB and Tox + FluB treated mice. Activation of both [1-(14)C]palmitic and [1-(14)C]octanoic acids was reduced in Tox-exposed mice at experimental day 12, but only when exogenous CoA was not included in the assay media; this effect appeared to persist after cessation of painting. Collectively, these data support the concept that Tox and FluB have independent effects on hepatic CoA metabolism that are associated with abnormalities in fatty-acid beta-oxidation. However, these do not fully explain the synergistic effect of the virus and chemical on beta-oxidation inhibition, which is a candidate co-mechanism for potentiation of mortality in this mouse model of AHE.

Infection concomitant with pediatric renal allograft rejection.

Renal allograft rejection episodes are frequent in children and often lead to allograft failure. Frequent association of fever with rejection in our transplant program provoked a prospective evaluation of concurrent infection during rejection episodes. Because cytomegalovirus has an established role in rejection and allograft survival, evaluation of cytomegalovirus and other herpes viruses (human simplex virus type 1, varicella, Epstein-Barr virus, and human herpes virus type 6 [HHV-6]) was undertaken in addition to standard bacterial investigation. A total of 37 patients were followed over a 30-month period. Six of eight rejection episodes were associated with herpes viruses (HHV-6, n = 6, and Epstein-Barr virus, n = 1). Three of the herpes-group-associated rejection episodes were treated with antiviral therapy in addition to pulse steroid treatment, with full recovery. The three patients with HHV-6-associated rejection episodes who were treated with pulse steroids, but no antiviral therapy, developed chronic allograft rejection. The recipient's response to allograft antigens may be influenced by concomitant herpes infection, and specific antiviral therapy appears to be indicated when infection is confirmed in association with rejection. An antiviral treatment program coupled with modulation of standard antirejection immunotherapy has the potential to improve morbidity and mortality in the pediatric renal transplant population.

Abnormalities in hepatic fatty-acid metabolism in a surfactant/influenza B virus mouse model for acute encephalopathy.

Abnormalities in fatty-acid metabolism are believed to play a role in nonspecific acute encephalopathy (AE) with hepatomegaly, although the specific nature of these abnormalities and their temporal relationship to the pathology are not well defined. We have examined hepatic fatty-acid beta-oxidation and metabolism in a mouse model for AE in which neonatal mice were exposed dermally to nontoxic doses of the industrial surfactant, Toximul MP8 (Tox), daily from days 1 to 12 after birth, and then infected with a sublethal dose (LD30) of mouse-adapted human influenza B (Lee) virus (FluB). The number of deaths in the group treated with Tox + FluB were significantly higher than those in the group infected with virus alone. Under optimal in vitro assay conditions, beta-oxidation of [1-14C]palmitic acid was approximately 15% higher in liver homogenates from mice painted with Tox for 12 days (P < 0.02); catabolism of [1-14C]octanoic acid to 14C-labelled water-soluble products (14C-WSP) and 14CO2 was unaltered by Tox. Infecting Tox-free mice with FluB inhibited beta-oxidation of both [1-14C]palmitate and [1-14C]octanoate by 20-30% (P < 0.001). On days 18-19, when most Tox + FluB-dependent deaths occurred, the inhibition of oxidation was increased to approximately 50% in mice given the combined treatment. Treatment of the mice with Tox/FluB also altered the pattern of incorporation of fatty acids into complex lipids. Hepatic levels of thiobarbituric acid reactive substance (TBARS), a marker for lipid peroxides, were approximately 15% higher in Tox-painted than in control mice (P < 0.01); FluB alone had no effect. In Tox + FluB-treated animals, TBARS levels were > 2-fold higher than in any other experimental group (P < 0.001). These studies demonstrated that nasally-administered FluB has profound effects on hepatic fatty-acid metabolism, particularly beta-oxidation. Exacerbation of this and related effects by exposing young animals to xenobiotic surfactants could be the basis of surfactant-mediated potentiation of virus-induced mortality.