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The effect of central nervous system inflammation on the levels and activity of hepatic and brain cytochrome P450 were examined in the rat. Brain ethoxyresorufin dealkylkase (EROD) was depressed during localized inflammatory responses evoked by lipopolysaccharide (LPS) injected into the lateral ventricle. This loss was accompanied by a concomitant loss of EROD activity and cytochrome P450 in liver. Similar losses in hepatic enzyme were observed for benzyloxy-resorufin and pentoxy-resorufin dealkylase (CYP2B) and chlorzoxazone hydroxylation (CYP2E). Protein levels of CYP2D and CYP2E1 but not CYP1A also were depressed. Similar i.p. doses of LPS had no effect on hepatic cytochrome P450, indicating that the hepatic effect was not caused by LPS leakage from the central nervous system. Also in support of this contention is that heat shock protein 27 was expressed throughout the brain by LPS given i.c. v. but was undetectable in the liver. Tumor necrosis factor-alpha given i.c.v. depressed EROD activity in the brain but this was not accompanied by a concomitant loss in the liver. Hepatic EROD did respond to the i.p. injection of tumor necrosis factor-alpha. The LPS-evoked loss in hepatic cytochrome P450 could not be prevented by blocking beta-receptor-mediated sympathetic nerve activity. This study demonstrates that localized inflammatory responses in the brain cause a concomitant down-regulation of cytochrome P450 and drug-metabolizing activity in the liver and the brain. The effect on brain cytochrome P450 may be regulated via cytokine-mediated pathways but signaling to the liver does not involve a cytokine-mediated pathway nor a beta-receptor-mediated sympathetic nerve pathway.

The level of cytochrome P-450 and the oxidation of aminopyrine and benzo(a)pyrene hydroxylase were depressed in hepatic microsomes prepared from mice infected with the gram positive bacteria Listeria monocytogenes. Maximum depression of mixed function oxidase occurred on the 2nd day of infection. This loss in drug biotransformation capacity in the liver was correlated directly with the number of organisms found in that organ. The ability of mice to metabolize drugs in vivo also was impaired during Listeria monocytogenes infection. During the infective period the half-life of theophylline was significantly prolonged and the N-demethylation of aminopyrine as measured by the expiration of 14CO2 from radiolabeled aminopyrine was diminished. The loss of drug metabolism was not due to interferon production, fever or morphological damage to the liver. These results indicate that certain bacterial infections can depress drug biotransformation and elimination in a similar manner to that already reported in viral and parasitic infections. This finding may be of significance to patients receiving drugs which are metabolized by the mixed function oxidase system during episodes of infection with some bacteria.

There have been numerous reports of altered drug clearance during episodes of viral infection and during the clinical use of recombinant interferons, but there have been very few reports regarding the effect of active bacterial infections on cytochrome P450-mediated metabolism. The objective of this study was to determine the mechanism by which the Gram-positive bacteria Listeria monocytogenes causes a depression of cytochrome P450-mediated biotransformation in mice. After induction with beta-napthoflavone, hepatic microsomal cytochrome P450 levels were reduced by 40% and ethoxyresorufin-O-dealkylase (EROD) activity was decreased by 65% in mice infected for 48 hr. The loss of EROD activity was accompanied by losses of cytochrome P450IA apoenzyme and cytochrome P450IA mRNA. Listeria infection did not affect total mRNA levels, as determined by oligo(dT)18 hybridization. The time course of these effects demonstrated that an up-regulation of cytochrome P450IA preceded the loss of this isozyme and that changes in cytochrome P450IA mRNA preceded the changes in apoenzyme levels and EROD activity. In hepatic microsomes from uninduced mice, cytochrome P450 levels and the rates of dealkylation of ethoxyresorufin, benzyloxyresorufin, pentoxyresorufin, and aminopyrine were significantly reduced, by 40-60%, after 48 hr of infection. The decrease in aminopyrine-N-demethylase activity was accompanied by a loss of cytochrome P450IID9 mRNA after 48 hr of infection. Cytochrome P450IID9 mRNA levels returned to normal after 96 hr of infection, whereas aminopyrine-N-demethylase activity was still decreased at this time. No up-regulation of cytochrome P450IID9 occured before the loss of this isozyme. The results of this study indicate that the changes in the levels of cytochrome P450IA and cytochrome P450IID9 that are observed during L. monocytogenes infection occur at a pretranslational step. If other bacteria have a similar capacity to depress cytochrome P450 by such a mechanism, then drugs with narrow therapeutic indices should be administered with caution during infectious diseases caused by bacteria or viruses.

Cytochrome P-450 and aryl hydrocarbon hydroxylase were depressed in microsomes prepared from the livers of mice treated with dextran sulfate. Unlike some other immune modulating drugs which decrease cytochrome P-450, dextran sulfate did not induce interferon production in the serum of these animals. Dextran sulfate had no effect on cytochrome P-450 when incubated with isolated hepatocytes alone but with mixtures of hepatocytes and Kupffer cells both cytochrome P-450 and aryl hydrocarbon hydroxylase were significantly depressed. Kupffer cells were then incubated at 37 degrees C for 30 min with dextran sulfate. After centrifugation the resulting cell-free supernatant decreased cytochrome P-450 and aryl hydrocarbon hydroxylase when incubated with hepatocytes. These experiments suggest that dextran sulfate stimulates the release of a factor by Kupffer cells which can decrease cytochrome P-450 in hepatocytes. This was confirmed by incubating cells in a membrane partitioned double-chambered Marbrook vessel to separate cell types and prevent passage of dextran sulfate. When dextran sulfate was added to the chamber containing Kupffer cells a factor was released which crossed a semipermeable membrane and depressed cytochrome P-450 levels in the hepatocytes in the other chamber. It is concluded that dextran sulfate depresses drug biotransformation in the liver via a factor which is released from Kupffer cells.

The elimination of phenytoin from blood was significantly decreased in rats pretreated 24 hr previously with Bordetella pertussis vaccine or the synthetic polynucleotide poly(rI.rC.). Phenytoin half-life was increased about 4-fold by both agents. In microsomes prepared from rats pretreated with B. pertussis vaccine or poly(rI.rC) the hydroxylation of phenytoin in vitro was decreased by 36 nad 53%, respectively. The addition of these agents to normal microsomal suspensions had no effect on phenytoin hydroxylation, demonstrating that the decrease in biotransformation was not due to direct enzyme inhibition. The decrease in phenytoin hydroxylation and elimination rate resulted from depressed levels of cytochrome P-450 in the hepatic endoplasmic reticulum of rats treated with B. pertussis vaccine or poly(rI.rC).

The down regulation of constitutive hepatic microsomal cytochromes P-450 (P450) by interferons has been well described in experimental animals and humans, however the down regulation of induced forms of P450 has not been documented clearly. Differential down regulation of constitutive and induced P450 could alter the proportions of P450 enzymes and, hence, the relative bioactivation/detoxification of xenobiotics. We investigated the effects of polyinosinic acid-polycytidylic acid, a potent stimulator of interferon alpha/beta production on CYP1A and CYP2E induction in the rat. Polyinosinic acid-polycytidylic acid down regulated the constitutive and pyridine-induced expression of CYP2E1 and the pyridine- and beta-naphthoflavone-induced expression of CYP1A1 as demonstrated by metabolic activity and immunoblot analyses. Depression of CYP2E1 and CYP1A1 protein expression by polyinosinic acid-polycytidylic acid was accompanied by a corresponding decrease in mRNA encoding these proteins. Induction of CYP1A2 mRNA also was depressed. Therefore, interferon alpha/beta down regulated induction of members of the CYP1A and CYP2E subfamilies at a pretranslational level independent of the mechanism of induction. Induction of the CYP1A and CYP2E subfamilies did not confer resistance to down regulation by interferon, although the magnitude of down regulation by interferon appeared to be influenced by the magnitude of P450 induction. The potential significance of down regulation of induced P450 in the clearance of certain therapeutic agents and in xenobiotic bioactivation and detoxification is discussed.

AimsTo establish the availability and completion of Advance Care Plans (ACP) in paediatric palliative hospice patients.To review changes to this in light of new guidance and following recommendations from a previous audit.ACPs are a valuable resource for patients, their families and healthcare professionals. Between the first and second audits there were two significant implementations. The National Institute for Health and Care Excellence (NICE) published guidelines about end of life care in children and young people in 2016. One of their quality statements is that all children with a life-limiting condition should be involved in developing an ACP. The second implementation was the adoption of the Children and Young Person’s Advance Care Plan (CYPACP) by the local palliative network.MethodsAll patients under the care of the palliative medical team were identified. Patients referred within the previous two months were excluded. Notes of all patients were reviewed and computer records accessed. The presence of an ACP was noted and, if available, was reviewed against set standards based on national recommendations. This included items such as patient identifiers, documented discussions about place of care, signature completion, and others.The first audit was done in December 2016 (n=41), with a repeat audit (to complete the cycle) in September 2017 (n=41) following institution of recommendations from the first audit. These recommendations included implementation of a teaching programme about using the new proforma (CYPACP).ResultsIn 2016, 80% of patients had ACPs. This improved in 2017 to 88%.In 2017, 25% were on CYPACP proforma compared to 6% in 2016.Patient identifiers were consistently well completed in both audits.Many ACPs were not signed (62% in 2016, 78% in 2017) which poses risk and challenges for nurses expected to follow documented recommendations.Discussion regarding place of care/death was completed in 100% of cases in 2017, compared to 79% in 2016.ConclusionThe process of writing ACPs is time intensive and transfer to new documentation is a significant undertaking. However, the introduction of the CYPACP has led to more comprehensively completed ACPs, particularly around place of care/death.