In vivo modulation of intestinal CYP3A metabolism by P-glycoprotein: studies using the rat single-pass intestinal perfusion model

P-Glycoprotein (P-gp) has been hypothesized to modulate intestinal drug metabolism by increasing the exposure of drug to intracellular CYP3A through repeated cycles of drug absorption and efflux. The rat single-pass intestinal perfusion model was used to study this interplay in vivo. N-Methyl piperazine-Phe-homoPhe-vinylsulfone phenyl (K77), a peptidomimetic cysteine protease inhibitor (CYP3A/P-gp substrate), and midazolam (CYP3A substrate) were each perfused through a segment of rat ileum alone and with the P-gp inhibitor N-(4-[2-(1,2,3,4-tetrahydro-6,7-dimethoxy-2-isoquinolinyl)-ethyl]-phenyl)-9,10-dihydro-5-methoxy-9-oxo-4-acridine carboxamine (GG918). Samples were obtained continuously from the outlet perfusate and the mesenteric vein at 5-min intervals for 40 to 60 min. The parent drug and two main metabolites of K77 (N-desmethyl and N-oxide) and midazolam (1-OH and 4-OH) were quantitated by liquid chromatography/mass spectrometry. K77 appearance in the mesenteric blood (P(blood) = 5 +/- 3 x 10(-6) cm/s) was increased 3-fold with GG918, whereas midazolam permeability (P(blood) = 1.1 +/- 0.3 x 10(-4) cm/s) was unchanged by GG918. K77 metabolites were preferentially excreted into the lumen, 4-OH midazolam was found equally in lumen and blood, and 1-OH was mainly excreted into blood. The extent of metabolism was estimated by calculating the fraction metabolized = 1 - P(blood)/P(lumen) and the extraction ratio (ER) determined from the direct measurement of known metabolites as ER = sum metabolites(all)/(sum metabolites(all) + drug in blood). When P-gp was inhibited, the fraction metabolized for K77 was decreased (95 to 85%) and the ER tended toward a decrease, whereas no differences in either parameter were observed for midazolam (not a P-gp substrate). These data support a role for P-gp in modulating the extent of intestinal metabolism in vivo by controlling drug access to the enzyme.     

High dose methadone and ventricular arrhythmias: a report of three cases

Three patients who developed torsades de pointes while receiving high dosages of oral methadone (>600mg/day) are presented. In all of the cases, drug interactions involving methadone and CYP3A4 isoenzyme system were possible. Two cases involve some previous cardiac impairment. The potential for toxic doses of methadone to cause ventricular arrhythmia is raised by these cases. Until further evidence is available it may be prudent to be vigilant for arrhythmias when high dosages of methadone (>600mg/day) are used, especially in patients on other drugs that interact with the CYP3A4 isoenzyme system, or with conditions that predispose to torsades de pointes.     

Cut the clutter with cycle time reduction

Users of cycle time reduction create process maps to identify and eliminate wasted resources. Consider implementing a similar process to streamline your facility's nursing model.     

Binding of polymeric IgG to fibronectin in extracellular matrices: an in vitro paradigm for immune-complex deposition

We have previously shown a biochemical interaction between fibronectin (Fn) and polymeric immunoglobulins (Igs), that we localized to the fourth and fifth N-terminal type I repeats (4F1.5F1) in Fn and the Fc portion of IgG. Therefore, we hypothesized that Fn, as a constituent of the extracellular matrix (ECM) may directly bind circulating immune complexes (ICs) causing their deposition, thereby contributing to the pathogenesis of IC diseases. As an in vitro paradigm to test this idea, we have generated Fn-containing ECMs from varied cells in culture and demonstrated a saturable dose-dependent binding of aggregated (agg) IgG, as a prototype of ICs, as well as the binding of both heat and cold aggregated purified type I cryoglobulins (CGs) to these ECMs. No binding was observed to ECMs (Matrigel) that do not contain Fn. Characteristic of our previous findings, polymeric but not monomeric IgG bound to the acellular Fn-containing ECMs. To further demonstrate the specificity of the interaction and implicate matrix Fn in the binding of aggIgG, complete inhibition of binding of aggIgG to Fn was achieved by blocking Fn on the ECMs with anti-Fn antiserum and by preincubation of the Ig aggregates with anti-human IgG antibodies. By competing the binding interaction with fluid phase Fn and the Ig-binding site on Fn, 4F(1).5F(1), 70% inhibition was obtained. Additional experiments performed with purified CGs show that an identical dose-dependent increase in Fn binding occurred using both preformed and forming cryoprecipitates suggesting that Fn does not confer cryoprecipitation of CGs and that the specific association of Fn with cryoprecipitates probably results from their polymeric configuration. Our results support the notion that Fn, as it exits in expanding ECMs characteristic of glomerulonephropathies and rheumatoid synovial disease, specifically interacts with complexed/polymeric Igs, thereby perpetuating IC deposition and playing a role in the pathogenesis of IC diseases.     

Telephone appointment visits for head and neck surgery follow-up care

OBJECTIVES/HYPOTHESIS: To test the hypothesis that patients with a variety of otolaryngologic diagnoses using telephone appointment visits would be equally as satisfied as patients receiving physician office visits, the study compared telephone appointment visits with physician office visits for health maintenance organization patients who needed routine follow-up care in a head and neck surgery clinic. STUDY DESIGN: Randomized, nonblinded cross-sectional study. METHODS: After their initial visit to either of two head and neck surgery clinics, new otolaryngology patients were randomly assigned into treatment and control groups. Patients in the treatment group (n = 73) received follow-up care in the form of telephone appointment visits, and patients in the control group (n = 80) received physician office visits for follow-up care. Study data were collected using telephone interviews and physician tracking forms. RESULTS: Patients receiving telephone appointment visits were significantly less satisfied with their visits than patients receiving physician office visits (chi2 = 25.4, P < .005). Patients who had physician office visits were significantly more likely than were patients in the treatment group to agree "somewhat" or "strongly" that 1) the physician addressed their questions and concerns (chi2 = 24.0, P < .005); 2) the physician provided personal care and attention (chi2 = 29.9, P <. 005); and 3) the physician provided high-quality care (chi2 = 34.5, P < .005). CONCLUSIONS: Patients who received telephone appointment visits were statistically significantly less satisfied with all aspects of their follow-up appointment than were patients who had physician office visits. The study findings indicate that telephone appointment visits may not be an ideal type of follow-up visit for all patients. Despite these findings, one third of patients in the treatment group would consider receiving a telephone appointment visit for future routine follow-up care, and 21.9% had no preference, perhaps a factor indicating willingness to receive a telephone appointment for a follow-up visit.     

The severity and nature of motor impairment in Asperger's syndrome: a comparison with specific developmental disorder of motor function

BACKGROUND: The aims of this study were to measure objectively the extent and severity of motor impairment in children with Asperger's syndrome and to determine whether the motor difficulties experienced by such children differed in any way from those classified as having a Specific Developmental Disorder of Motor Function (SDD-MF). Criteria derived from ICD 10-R were used to identify 11 children with Asperger's syndrome and a matched group of 9 children with a Specific Developmental Disorder of Motor Function. Children in both groups were required to have a verbal IQ of 80 or greater on the WISC IIIR. METHOD: The Autism Diagnostic Interview (Revised; Lord, Rutter, & LeCouteur, 1994) was used to identify features of AS in the first group and to exclude them in the latter. The Movement Assessment Battery for Children (Henderson & Sugden, 1992) provided a standardised test of motor impairment. A Gesture Test based on that by Cermak, Coster, and Drake (1980) was used to assess the child's ability to mime the use of familiar tools and to imitate meaningless sequences of movements. RESULTS: All the children with Asperger's syndrome turned out to meet our criterion for a diagnosis of motor impairment, five of the six most severely motor impaired children in the whole study being from this group. Performance of the Asperger group was also slightly poorer on the Gesture Test. The profile of performance on each test was examined in detail but no evidence of group differences in the pattern of impairment was found. CONCLUSIONS: This study is consistent with others suggesting a high prevalence of clumsiness in Asperger's syndrome. Our findings also attest to the widespread prevalence of motor impairment in developmental disorders and the problems such co-morbidity poses for attempts to posit discrete and functionally coherent impairments underlying distinct syndromes.     

Go wireless to spark productivity

The mother/baby unit of Ohio's Good Samaritan Hospital instituted a wireless communication system. Here, review its benefits.     

Medical management of the cardiac infant and child after surgical discharge

Congenital heart disease (CHD) presents medical management challenges throughout the lifespan. As the complexity of the lesion increases, so do the management challenges. These issues include medication use; short-term postoperative management monitoring of growth, nutrition, development, family impact, immunization; and long-term management issues. The knowledge base in this field is ever growing, and only with knowing what to expect can we identify the unexpected and make that part of our understanding of the care of children with CHD.