1 The possibility that the endothelium-derived hyperpolarising factor (EDHF) in the rat hepatic artery is a cytochrome P450 mono-oxygenase metabolite of arachidonic acid was examined in the present study. In this preparation, acetylcholine elicits EDHF-mediated relaxations in the presence of the nitric oxide (NO) synthase and cyclo-oxygenase inhibitors No-nitro-L-arginine (L-NOARG) and indomethacin, respectively.2 17-Octadecynoic acid (17-ODYA, 50 gM), a suicide-substrate inhibitor of the cytochrome P450 mono-oxygenases responsible for the production of 5, 8, 11,[12][13][14], had no effect on acetylcholine-induced relaxations in the presence of L-NOARG (0.3 mM) plus indomethacin (10 gM). Furthermore, 5, 8, 11, Clotrimazole (3 gM) was without effect on these responses. The relaxant actions of the NO donor, 3-morpholino-sydnonimine, were unaffected by proadifen (10 gM). 5 The relaxant effects of the opener of ATP-sensitive potassium channels, levcromakalim, were abolished by proadifen (10 gM) and strongly attenuated by clotrimazole (3 gM). Proadifen (10 gM) also abolished the hyperpolarization induced by levcromakalim (1 gM). 6 The lack of effect of 17-ODYA on relaxations mediated by EDHF, together with the failure of extracellularly-applied EETs to produce relaxation, collectively suggest that EDHF is not an EET in the rat hepatic artery. It seems likely that inhibition of ion channels in the smooth muscle rather than reduced EDHF formation in the endothelium offers a better explanation for the actions of the cytochrome P450 inhibitors proadifen and clotrimazole.

Objectives Recent reports demonstrate a link between Inflammatory Bowel Disease (IBD) and sleep disturbance. Increased psychiatric dysfunction is consistently reported in patients with IBD. Our objective is to examine relationships among sleep disturbance, inflammation, and psychiatric dysfunction in a pediatric population with Crohn’s disease (CD) and depression. Methods Pediatric CD patients with depression (n = 96) and healthy controls (n = 19) completed measures of sleep (Pittsburgh Sleep Quality Index [PSQI]), depression, anxiety, and abdominal pain, and provided blood for inflammatory markers. CD activity was determined by Pediatric Crohn’s Disease Activity Index (PCDAI). Factor analysis was performed on subscales of the PSQI in order to derive measures of sleep disturbance. Univariate and multivariate regression analyses assessed relationships between sleep disturbance, psychosocial, and biological measures of CD and psychiatric dysfunction. Results Sleep disturbance in depressed youth with CD was significantly greater than healthy controls, and was significantly related to measures of abdominal pain, depression, and anxiety, but not biomarkers of inflammation. Factor analysis of the PSQI demonstrated a two-factor solution. The first factor, termed ‘Qualitative,’ included Subjective Sleep Quality, Daytime Dysfunction, Sleep Disturbance, and Sleep Latency, whereas the second, ‘Quantitative,’ factor consisted of Habitual Sleep Efficiency and Sleep Duration. This factor showed a significant relationship with inflammatory markers. Multivariate modeling suggested Qualitative sleep disturbance was predicted by disease activity, pain, and anxiety whereas Quantitative sleep disturbance was predicted by disease activity. Conclusions These results indicate that sleep disturbance in depressed CD sufferers differs depending upon illness activity. Patients may require different interventions depending upon the sleep disturbance exhibited.

Little information is available on the active site structure of the CYP4A family of enzymes or the mechanism by which their omega-hydroxylation regiospecificity is enforced. We report here that the E320A, D323E, and E320/D323E mutations decrease the catalytic rate of CYP4A1 approximately 5-fold and cause up to a 10-fold shift from omega- to (omega-1)-hydroxylation. The decreased catalytic rate is due to an increase in the uncoupled reduction of molecular oxygen. Tighter binding of 1- and 4-substituted imidazoles to the double mutant than to the other proteins suggests that its active site is less constrained. The reaction of these proteins with phenyldiazene causes heme degradation without the detectable formation of a phenyl-iron complex. CYP4A1 and its E320A mutant are not inactivated by 1-aminobenzotriazole (1-ABT), but the D323E and E320A/D323E mutants are inactivated. The resistance of purified CYP4A1 to inactivation by 1-ABT is surprising in view of the fact that 1-ABT causes the loss of the omega-hydroxylase activity both in microsomal preparations and in vivo. Collectively, the results establish that Glu-320, and particularly Asp-323, help to define the active site dimensions, the degree of coupled versus uncoupled versus uncoupled turnover, the omega-versus (omega-1)-hydroxylation regiospecificity, and the susceptibility to inactivation by mechanism-based inhibitors. Furthermore, they provide experimental evidence for a structural analogy between the CYP4A1 and P450BM-3 active sites.

Suicidal ideation (SI) is a common presenting problem for psychiatric hospitalizations in adolescents and often persists following discharge. This study examines whether distinct trajectories of SI could be delineated following hospitalization and the risk factors most strongly related to these trajectories. Adolescents (N = 104; 76 females; 28 males) were followed for 6 months after discharge from inpatient or partial hospitalization. Semi-parametric group modeling identified SI trajectory group membership. In all, 33.7% of adolescents fell in a Subclinical SI group, 43.3% in a Declining SI group, and 23.1% in a Chronic SI group. Multinomial logistic regression was utilized to examine baseline predictors of group membership. Emotion dysregulation differentiated Chronic SI from Declining SI. In multivariate analyses, adolescents endorsing greater non-acceptance of emotional responses (OR =1.18) and more limited access to emotion regulation strategies (OR =1.12) were more likely to belong to the Chronic SI than Declining SI trajectory. Those in the Chronic SI group also had the greatest number of suicide attempts and hospitalizations in the 6 months post-discharge. These results suggest that clinicians should closely monitor and address emotion dysregulation when assessing suicide risk. Greater dysregulation may require more intensive services in order to have an effect on chronic SI.