Showing papers by "Vanderbilt University published in 2002"

Comparison of four chemotherapy regimens for advanced non-small-cell lung cancer.

Abstract: Background We conducted a randomized study to determine whether any of three chemotherapy regimens was superior to cisplatin and paclitaxel in patients with advanced non–small-cell lung cancer. Methods A total of 1207 patients with advanced non–small-cell lung cancer were randomly assigned to a reference regimen of cisplatin and paclitaxel or to one of three experimental regimens: cisplatin and gemcitabine, cisplatin and docetaxel, or carboplatin and paclitaxel. Results The response rate for all 1155 eligible patients was 19 percent, with a median survival of 7.9 months (95 percent confidence interval, 7.3 to 8.5), a 1-year survival rate of 33 percent (95 percent confidence interval, 30 to 36 percent), and a 2-year survival rate of 11 percent (95 percent confidence interval, 8 to 12 percent). The response rate and survival did not differ significantly between patients assigned to receive cisplatin and paclitaxel and those assigned to receive any of the three experimental regimens. Treatment with cisplatin...

Matrix Metalloproteinase Inhibitors and Cancer—Trials and Tribulations

Abstract: For at least 30 years, matrix metalloproteinases (MMPs) have been heralded as promising targets for cancer therapy on the basis of their massive up-regulation in malignant tissues and their unique ability to degrade all components of the extracellular matrix. Preclinical studies testing the efficacy of MMP suppression in tumor models were so compelling that synthetic metalloproteinase inhibitors (MPIs) were rapidly developed and routed into human clinical trials. The results of these trials have been disappointing. Here we review the studies that brought MPIs into clinical testing and discuss the design and outcome of the trials in light of new information about the cellular source, substrates, and mode of action of MMPs at different stages of tumor progression. The important lessons learned from the MPI experience may be of great value for future studies of MPIs and for cancer drug development in general.

American Cancer Society Guidelines on Nutrition and Physical Activity for Cancer Prevention: Reducing the Risk of Cancer with Healthy Food Choices and Physical Activity

Abstract: The American Cancer Society (ACS) publishes Nutrition and Physical Activity Guidelines to serve as a foundation for its communication, policy, and community strategies and ultimately, to affect dietary and physical activity patterns among Americans. These Guidelines, published every 5 years, are developed by a national panel of experts in cancer research, prevention, epidemiology, public health, and policy, and as such, they represent the most current scientific evidence related to dietary and activity patterns and cancer risk. The ACS Guidelines include recommendations for individual choices regarding diet and physical activity patterns, but those choices occur within a community context that either facilitates or interferes with healthy behaviors. Community efforts are essential to create a social environment that promotes healthy food choices and physical activity. Therefore, this committee presents one key recommendation for community action to accompany the four recommendations for individual choices to reduce cancer risk. This recommendation for community action recognizes that a supportive social environment is indispensable if individuals at all levels of society are to have genuine opportunities to choose healthy behaviors. The ACS Guidelines are consistent with guidelines from the American Heart Association and the American Diabetes Association for the prevention of coronary heart disease and diabetes, as well as for general health promotion, as defined by the Department of Health and Human Services' 2005 Dietary Guidelines for Americans.

Evidence that fibroblasts derive from epithelium during tissue fibrosis

Abstract: Interstitial fibroblasts are principal effector cells of organ fibrosis in kidneys, lungs, and liver While some view fibroblasts in adult tissues as nothing more than primitive mesenchymal cells surviving embryologic development, they differ from mesenchymal cells in their unique expression of fibroblast-specific protein-1 (FSP1) This difference raises questions about their origin Using bone marrow chimeras and transgenic reporter mice, we show here that interstitial kidney fibroblasts derive from two sources A small number of FSP1(+), CD34(-) fibroblasts migrate to normal interstitial spaces from bone marrow More surprisingly, however, FSP1(+) fibroblasts also arise in large numbers by local epithelial-mesenchymal transition (EMT) during renal fibrogenesis Both populations of fibroblasts express collagen type I and expand by cell division during tissue fibrosis Our findings suggest that a substantial number of organ fibroblasts appear through a novel reversal in the direction of epithelial cell fate As a general mechanism, this change in fate highlights the potential plasticity of differentiated cells in adult tissues under pathologic conditions

Dual-chamber pacing or ventricular backup pacing in patients with an implantable defibrillator: the Dual Chamber and VVI Implantable Defibrillator (DAVID) Trial.

Abstract: CONTEXT: Implantable cardioverter defibrillator (ICD) therapy with backup ventricular pacing increases survival in patients with life-threatening ventricular arrhythmias. Most currently implanted ICD devices provide dual-chamber pacing therapy. The most common comorbid cause for mortality in this population is congestive heart failure. OBJECTIVE: To determine the efficacy of dual-chamber pacing compared with backup ventricular pacing in patients with standard indications for ICD implantation but without indications for antibradycardia pacing. DESIGN: The Dual Chamber and VVI Implantable Defibrillator (DAVID) Trial, a single-blind, parallel-group, randomized clinical trial. SETTING AND PARTICIPANTS: A total of 506 patients with indications for ICD therapy were enrolled between October 2000 and September 2002 at 37 US centers. All patients had a left ventricular ejection fraction (LVEF) of 40% or less, no indication for antibradycardia pacemaker therapy, and no persistent atrial arrhythmias. INTERVENTIONS: All patients had an ICD with dual-chamber, rate-responsive pacing capability implanted. Patients were randomly assigned to have the ICDs programmed to ventricular backup pacing at 40/min (VVI-40; n = 256) or dual-chamber rate-responsive pacing at 70/min (DDDR-70; n = 250). Maximal tolerated medical therapy for left ventricular dysfunction, including angiotensin-converting enzyme inhibitors and beta-blockers, was prescribed to all patients. MAIN OUTCOME MEASURE: Composite end point of time to death or first hospitalization for congestive heart failure. RESULTS: One-year survival free of the composite end point was 83.9% for patients treated with VVI-40 compared with 73.3% for patients treated with DDDR-70 (relative hazard, 1.61; 95% confidence interval [CI], 1.06-2.44). The components of the composite end point, mortality of 6.5% for VVI-40 vs 10.1% for DDDR-70 (relative hazard, 1.61; 95% CI, 0.84-3.09) and hospitalization for congestive heart failure of 13.3% for VVI-40 vs 22.6% for DDDR-70 (relative hazard, 1.54; 95% CI, 0.97-2.46), also trended in favor of VVI-40 programming. CONCLUSION: For patients with standard indications for ICD therapy, no indication for cardiac pacing, and an LVEF of 40% or less, dual-chamber pacing offers no clinical advantage over ventricular backup pacing and may be detrimental by increasing the combined end point of death or hospitalization for heart failure.

Helicobacter pylori and gastrointestinal tract adenocarcinomas

Abstract: Although gastric adenocarcinoma is associated with the presence of Helicobacter pylori in the stomach, only a small fraction of colonized individuals develop this common malignancy. H. pylori strain and host genotypes probably influence the risk of carcinogenesis by differentially affecting host inflammatory responses and epithelial-cell physiology. Understanding the host-microbial interactions that lead to neoplasia will improve cancer-targeted therapeutics and diagnostics, and provide mechanistic insights into other malignancies that arise within the context of microbially initiated inflammatory states.

Effect of Dialysis Dose and Membrane Flux in Maintenance Hemodialysis

Abstract: Background The effects of the dose of dialysis and the level of flux of the dialyzer membrane on mortality and morbidity among patients undergoing maintenance hemodialysis are uncertain. Methods We undertook a randomized clinical trial in 1846 patients undergoing thrice-weekly dialysis, using a two-by-two factorial design to assign patients randomly to a standard or high dose of dialysis and to a low-flux or high-flux dialyzer. Results In the standard-dose group, the mean (±SD) urea-reduction ratio was 66.3±2.5 percent, the single-pool Kt/V was 1.32±0.09, and the equilibrated Kt/V was 1.16±0.08; in the high-dose group, the values were 75.2±2.5 percent, 1.71±0.11, and 1.53±0.09, respectively. Flux, estimated on the basis of beta2-microglobulin clearance, was 3±7 ml per minute in the low-flux group and 34±11 ml per minute in the high-flux group. The primary outcome, death from any cause, was not significantly influenced by the dose or flux assignment: the relative risk of death in the high-dose group as com...

A Role for Uric Acid in the Progression of Renal Disease

Abstract: . Hyperuricemia is associated with renal disease, but it is usually considered a marker of renal dysfunction rather than a risk factor for progression. Recent studies have reported that mild hyperuricemia in normal rats induced by the uricase inhibitor, oxonic acid (OA), results in hypertension, intrarenal vascular disease, and renal injury. This led to the hypothesis that uric acid may contribute to progressive renal disease. To examine the effect of hyperuricemia on renal disease progression, rats were fed 2% OA for 6 wk after 5/6 remnant kidney (RK) surgery with or without the xanthine oxidase inhibitor, allopurinol, or the uricosuric agent, benziodarone. Renal function and histologic studies were performed at 6 wk. Given observations that uric acid induces vascular disease, the effect of uric acid on vascular smooth muscle cells in culture was also examined. RK rats developed transient hyperuricemia (2.7 mg/dl at week 2), but then levels returned to baseline by week 6 (1.4 mg/dl). In contrast, RK+OA rats developed higher and more persistent hyperuricemia (6 wk, 3.2 mg/dl). Hyperuricemic rats demonstrated higher BP, greater proteinuria, and higher serum creatinine than RK rats. Hyperuricemic RK rats had more renal hypertrophy and greater glomerulosclerosis (24.2 ± 2.5 versus 17.5 ± 3.4%; P versus 1.52 ± 0.47; P in vitro studies, cultured vascular smooth muscle cells incubated with uric acid also generated COX-2 with time-dependent proliferation, which was prevented by either a COX-2 or TXA-2 receptor inhihbitor. Hyperuricemia accelerates renal progression in the RK model via a mechanism linked to high systemic BP and COX-2-mediated, thromboxane-induced vascular disease. These studies provide direct evidence that uric acid may be a true mediator of renal disease and progression.

Matrix metalloproteinases: a tail of a frog that became a prince

Abstract: It is 40 years since the first member of what came to be known as the matrix metalloproteinase (MMP) family was described. Structural, molecular and biochemical approaches have subsequently contributed to piecing together the puzzle of how MMPs work, and how they contribute to various disease processes.

Biliverdin reductase: a major physiologic cytoprotectant.

Abstract: Bilirubin, an abundant pigment that causes jaundice, has long lacked any clear physiologic role. It arises from enzymatic reduction by biliverdin reductase of biliverdin, a product of heme oxygenase activity. Bilirubin is a potent antioxidant that we show can protect cells from a 10,000-fold excess of H2O2. We report that bilirubin is a major physiologic antioxidant cytoprotectant. Thus, cellular depletion of bilirubin by RNA interference markedly augments tissue levels of reactive oxygen species and causes apoptotic cell death. Depletion of glutathione, generally regarded as a physiologic antioxidant cytoprotectant, elicits lesser increases in reactive oxygen species and cell death. The potent physiologic antioxidant actions of bilirubin reflect an amplification cycle whereby bilirubin, acting as an antioxidant, is itself oxidized to biliverdin and then recycled by biliverdin reductase back to bilirubin. This redox cycle may constitute the principal physiologic function of bilirubin.

The role of the transcriptional regulator Ptf1a in converting intestinal to pancreatic progenitors

Abstract: Pancreas development begins with the formation of buds at specific sites in the embryonic foregut endoderm. We used recombination-based lineage tracing in vivo to show that Ptf1a (also known as PTF1-p48) is expressed at these early stages in the progenitors of pancreatic ducts, exocrine and endocrine cells, rather than being an exocrine-specific gene as previously described. Moreover, inactivation of Ptf1a switches the character of pancreatic progenitors such that their progeny proliferate in and adopt the normal fates of duodenal epithelium, including its stem-cell compartment. Consistent with the proposal that Ptf1a supports the specification of precursors of all three pancreatic cell types, transgene-based expression of Pdx1, a gene essential to pancreas formation, from Ptf1a cis-regulatory sequences restores pancreas tissue to Pdx1-null mice that otherwise lack mature exocrine and endocrine cells because of an early arrest in organogenesis. These experiments provide evidence that Ptf1a expression is specifically connected to the acquisition of pancreatic fate by undifferentiated foregut endoderm.

The BABAR detector

Abstract: BABAR, the detector for the SLAC PEP-II asymmetric e+e- B Factory operating at the upsilon 4S resonance, was designed to allow comprehensive studies of CP-violation in B-meson decays. Charged particle tracks are measured in a multi-layer silicon vertex tracker surrounded by a cylindrical wire drift chamber. Electromagentic showers from electrons and photons are detected in an array of CsI crystals located just inside the solenoidal coil of a superconducting magnet. Muons and neutral hadrons are identified by arrays of resistive plate chambers inserted into gaps in the steel flux return of the magnet. Charged hadrons are identified by dE/dx measurements in the tracking detectors and in a ring-imaging Cherenkov detector surrounding the drift chamber. The trigger, data acquisition and data-monitoring systems, VME- and network-based, are controlled by custom-designed online software. Details of the layout and performance of the detector components and their associated electronics and software are presented.

An Analysis of Outcomes of Reconstruction or Amputation after Leg-Threatening Injuries

Abstract: Background Limb salvage for severe trauma has replaced amputation as the primary treatment in many trauma centers. However, long-term outcomes after limb reconstruction or amputation have not been fully evaluated. Methods We performed a multicenter, prospective, observational study to determine the functional outcomes of 569 patients with severe leg injuries resulting in reconstruction or amputation. The principal outcome measure was the Sickness Impact Profile, a multidimensional measure of self-reported health status (scores range from 0 to 100; scores for the general population average 2 to 3, and scores greater than 10 represent severe disability). Secondary outcomes included limb status and the presence or absence of major complications resulting in rehospitalization. Results At two years, there was no significant difference in scores for the Sickness Impact Profile between the amputation and reconstruction groups (12.6 vs. 11.8, P=0.53). After adjustment for the characteristics of the patients and t...

PKB/Akt mediates cell-cycle progression by phosphorylation of p27(Kip1) at threonine 157 and modulation of its cellular localization.

Abstract: We have shown a novel mechanism of Akt-mediated regulation of the CDK inhibitor p27kip1. Blockade of HER2/neu in tumor cells inhibits Akt kinase activity and upregulates nuclear levels of the CDK inhibitor p27Kip1. Recombinant Akt and Akt precipitated from tumor cells phosphorylated wild-type p27 in vitro. p27 contains an Akt consensus RXRXXT157D within its nuclear localization motif. Active (myristoylated) Akt phosphorylated wild-type p27 in vivo but was unable to phosphorylate a T157A-p27 mutant. Wild-type p27 localized in the cytosol and nucleus, whereas T157A-p27 localized exclusively in the nucleus and was resistant to nuclear exclusion by Akt. T157A-p27 was more effective than wild-type p27 in inhibiting cyclin E/CDK2 activity and cell proliferation; these effects were not rescued by active Akt. Expression of Ser473 phospho Akt in primary human breast cancers statistically correlated with expression of p27 in tumor cytosol. These data indicate that Akt may contribute to tumor-cell proliferation by phosphorylation and cytosolic retention of p27, thus relieving CDK2 from p27-induced inhibition.

Does Net Buying Pressure Affect the Shape of Implied Volatility Functions

Abstract: This paper examines the relation between net buying pressure and the shape of the implied volatility function (IVF) of S&P 500 index options and options on twenty individual stocks. We find that time variation in the implied volatility of an option series is directly related to net buying pressure from public order flow. We also find that movements in implied volatility in the index option market are most strongly affected by buying pressure for index puts, while call options tend to dominate in stock option markets. Simulated delta-neutral trading strategies that sell options generate abnormal returns that match the deviations of the IVFs from historical volatility levels. Index option abnormal returns decrease monotonically across exercise prices and are significant, while stock option abnormal returns are symmetric, smaller, and insignificant. When vega risk is also hedged in the simulations using index options, however, the abnormal returns go from positive to negative, indicating that the steeply sloped IVF for index options does not present a profitable arbitrage opportunity once the costs of hedging have been considered.

Postsynaptic endocannabinoid release is critical to long-term depression in the striatum.

Abstract: The striatum functions critically in movement control and habit formation. The development and function of cortical input to the striatum are thought to be regulated by activity-dependent plasticity of corticostriatal glutamatergic synapses. Here we show that the induction of a form of striatal synaptic plasticity, long-term depression (LTD), is dependent on activation of the CB1 cannabinoid receptor. LTD was facilitated by blocking cellular endocannabinoid uptake, and postsynaptic loading of anandamide (AEA) produced presynaptic depression. The endocannabinoid necessary for striatal LTD is thus likely to be released postsynaptically as a retrograde messenger. These findings demonstrate a new role for endocannabinoids in the induction of long-term synaptic plasticity in a circuit necessary for habit formation and motor control.

Phase III Study of Gemcitabine in Combination With Fluorouracil Versus Gemcitabine Alone in Patients With Advanced Pancreatic Carcinoma: Eastern Cooperative Oncology Group Trial E2297

Abstract: PURPOSE: Gemcitabine is generally considered to constitute first-line therapy for pancreatic cancer. To determine whether the addition of fluorouracil (5-FU) improves on the results from single-agent gemcitabine, the Eastern Cooperative Oncology Group (ECOG) compared gemcitabine plus bolus 5-FU with gemcitabine alone for patients with advanced pancreatic carcinoma. PATIENTS AND METHODS: This trial involved patients with biopsy-proven, advanced carcinoma of the pancreas not amenable to surgical resection. Patients were randomized to receive either gemcitabine alone (1,000 mg/m2/wk) weekly for 3 weeks of every 4 or to receive gemcitabine (1,000 mg/m2/wk) followed by 5-FU (600 mg/m2/wk) weekly on the same schedule. The primary end point of the trial was survival, with secondary end points of time to progression and response rate. RESULTS: Of 327 patients enrolled over 18 months, 322 were eligible. Overall, the median survival was 5.4 months for gemcitabine alone and 6.7 months for gemcitabine plus 5-FU (P = ...

Global Gene Profiling in Human Endometrium during the Window of Implantation

Abstract: Implantation in humans is a complex process that is temporally and spatially restricted. Over the past decade, using a one-by-one approach, several genes and gene products that may participate in this process have been identified in secretory phase endometrium. Herein, we have investigated global gene expression during the window of implantation (peak E2 and progesterone levels) in well characterized human endometrial biopsies timed to the LH surge, compared with the late proliferative phase (peak E2 level) of the menstrual cycle. Tissues were processed for poly(A+) RNA and hybridization of chemically fragmented, biotinylated cRNAs on high density oligonucleotide microarrays, screening for 12,686 genes and expressed sequence tags. After data normalization, mean values were obtained for gene readouts and fold ratios were derived comparing genes up- and down-regulated in the window of implantation vs. the late proliferative phase. Nonparametric testing revealed 156 significantly (P < 0.05) up-regulated gene...

G protein-coupled receptors in Anopheles gambiae.

Abstract: We used bioinformatic approaches to identify a total of 276 G protein-coupled receptors (GPCRs) from the Anopheles gambiae genome. These include GPCRs that are likely to play roles in pathways affecting almost every aspect of the mosquito's life cycle. Seventy-nine candidate odorant receptors were characterized for tissue expression and, along with 76 putative gustatory receptors, for their molecular evolution relative to Drosophila melanogaster. Examples of lineage-specific gene expansions were observed as well as a single instance of unusually high sequence conservation.

Regulation of insulin action and pancreatic beta-cell function by mutated alleles of the gene encoding forkhead transcription factor Foxo1.

Abstract: Type 2 diabetes results from impaired action and secretion of insulin. It is not known whether the two defects share a common pathogenesis. We show that haploinsufficiency of the Foxo1 gene, encoding a forkhead transcription factor (forkhead box transcription factor O1), restores insulin sensitivity and rescues the diabetic phenotype in insulin-resistant mice by reducing hepatic expression of glucogenetic genes and increasing adipocyte expression of insulin-sensitizing genes. Conversely, a gain-of-function Foxo1 mutation targeted to liver and pancreatic β-cells results in diabetes arising from a combination of increased hepatic glucose production and impaired β-cell compensation due to decreased Pdx1 expression. These data indicate that Foxo1 is a negative regulator of insulin sensitivity in liver, adipocytes and pancreatic β-cells. Impaired insulin signaling to Foxo1 provides a unifying mechanism for the common metabolic abnormalities of type 2 diabetes. NOTE: In the AOP version of this article, the name of the fourth author was misspelled as W K Cavanee rather than the correct spelling: W K Cavenee. This has been corrected in the full-text online version of the article. The name will appear correctly in the print version.

Cyclooxygenase-2: a therapeutic target.

Abstract: ▪ Abstract Cyclooxygenase (COX), also known as prostaglandin endoperoxide synthase, is the key enzyme required for the conversion of arachidonic acid to prostaglandins. Two COX isoforms have been identified, COX-1 and COX-2. In many situations, the COX-1 enzyme is produced constitutively (e.g., in gastric mucosa), whereas COX-2 is highly inducible (e.g., at sites of inflammation and cancer). Traditional nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit both enzymes, and a new class of COX-2 selective inhibitors (COXIBs) preferentially inhibit the COX-2 enzyme. This review summarizes our current understanding of the role of COX-1 and COX-2 in normal physiology and disease.

Herceptin-induced Inhibition of Phosphatidylinositol-3 Kinase and Akt Is Required for Antibody-mediated Effects on p27, Cyclin D1, and Antitumor Action

Abstract: We have examined whether inhibition of phosphatidylinositol-3 kinase (PI3K) and its target, the serine/threonine kinase Akt, play a role in the antitumor effect of the HER2 antibody Herceptin. Herceptin inhibited colony formation, down-regulated cyclin D1, and increased p27 protein levels in the HER2 gene-amplified BT-474 and SKBR-3 human breast cancer cells. These effects were temporally associated with the inhibition of PI3K activity in vitro as well as Akt function as measured by steady-state levels of phospho-Ser473 Akt and kinase activity against glycogen synthase kinase (GSK)-3beta. These responses were not observed in MDA-361 and MDA-453 cells, which do not exhibit HER2 gene amplification and are relatively resistant to Herceptin. Treatment of BT-474 cells with Herceptin inhibited the constitutive tyrosine phosphorylation of HER3 and disrupted the basal association of HER3 with HER2 and of HER3 with p85alpha potentially explaining the inhibition of PI3K. Treatment with either Herceptin or the PI3K inhibitor LY294002 increased the levels of p27 in the nucleus>cytosol, thus increasing the ratio of p27:Cdk2 in the nucleus and inhibiting Cdk2 activity and cell proliferation. Antisense p27 oligonucleotides abrogated the increase in p27 induced by Herceptin and prevented the antibody-mediated reduction in S phase. Transduction of BT-474 cells with an adenovirus-encoding active (myristoylated) Akt (Myr-Akt), but not with a beta-galactosidase control adenovirus, prevented the Herceptin- or LY294002-induced down-regulation of cyclin D1 and of phosphorylated GSK-3beta and prevented the accumulation of p27 in the nucleus and cytosol. In addition, Myr-Akt prevented Herceptin-induced inhibition of the cell proliferation of BT-474 cells and Herceptin-induced apoptosis of SKBR-3 cells. These data suggest that (a) changes in cell cycle- and apoptosis-regulatory molecules after HER2 blockade with Herceptin result, at least in part, from the inhibition of Akt; and (b) disabling PI3K and Akt is required for the antitumor effect of HER2 inhibitors.

Party Polarization and "Conflict Extension" in the American Electorate

Abstract: agendas have remained distinct, but the parties in the electorate have grown more polarized on all three. Conflict extension. rather than conflict displacement or ideological realign? ment, has occurred because there has been a limited mass response to the growth of elite-level party polar? ization. Only party identifiers who are aware of party elite polarization on each of the issue dimensions have

Regulation of corepressor function by nuclear NADH.

Abstract: The corepressor CtBP (carboxyl-terminal binding protein) is involved in transcriptional pathways important for development, cell cycle regulation, and transformation. We demonstrate that CtBP binding to cellular and viral transcriptional repressors is regulated by the nicotinamide adenine dinucleotides NAD+ and NADH, with NADH being two to three orders of magnitude more effective. Levels of free nuclear nicotinamide adenine dinucleotides, determined using two-photon microscopy, correspond to the levels required for half-maximal CtBP binding and are considerably lower than those previously reported. Agents capable of increasing NADH levels stimulate CtBP binding to its partners in vivo and potentiate CtBP-mediated repression. We propose that this ability to detect changes in nuclear NAD+/NADH ratio allows CtBP to serve as a redox sensor for transcription.

Shotgun identification of protein modifications from protein complexes and lens tissue

Abstract: Large-scale genomics has enabled proteomics by creating sequence infrastructures that can be used with mass spectrometry data to identify proteins. Although protein sequences can be deduced from nucleotide sequences, posttranslational modifications to proteins, in general, cannot. We describe a process for the analysis of posttranslational modifications that is simple, robust, general, and can be applied to complicated protein mixtures. A protein or protein mixture is digested by using three different enzymes: one that cleaves in a site-specific manner and two others that cleave nonspecifically. The mixture of peptides is separated by multidimensional liquid chromatography and analyzed by a tandem mass spectrometer. This approach has been applied to modification analyses of proteins in a simple protein mixture, Cdc2p protein complexes isolated through the use of an affinity tag, and lens tissue from a patient with congenital cataracts. Phosphorylation sites have been detected with known stoichiometry of as low as 10%. Eighteen sites of four different types of modification have been detected on three of the five proteins in a simple mixture, three of which were previously unreported. Three proteins from Cdc2p isolated complexes yielded eight sites containing three different types of modifications. In the lens tissue, 270 proteins were identified, and 11 different crystallins were found to contain a total of 73 sites of modification. Modifications identified in the crystallin proteins included Ser, Thr, and Tyr phosphorylation, Arg and Lys methylation, Lys acetylation, and Met, Tyr, and Trp oxidations. The method presented will be useful in discovering co- and posttranslational modifications of proteins.

Fruit juices inhibit organic anion transporting polypeptide-mediated drug uptake to decrease the oral availability of fexofenadine.

Abstract: Objectives Our objective was to examine the effect of different fruits and their constituents on P-glycoprotein and organic anion transporting polypeptide (OATP) activities in vitro and on drug disposition in humans. Methods P-glycoprotein–mediated digoxin or vinblastine efflux was determined in polarized epithelial cell monolayers. OATP-mediated fexofenadine uptake was measured in a transfected cell line. The oral pharmacokinetics of 120 mg fexofenadine was assessed with water, 25%-strength grapefruit juice, or normal-strength grapefruit, orange, or apple juices (1.2 L over 3 hours) in a randomized 5-way crossover study in 10 healthy subjects. Results Grapefruit juice and segments and apple juice at 5% of normal strength did not alter P-glycoprotein activity. Grapefruit extract reduced transport. 6′,7′-Dihydroxybergamottin had modest inhibitory activity (50% inhibitory concentration [IC50], 33 μmol/L). In contrast, grapefruit, orange, and apple juices at 5% of normal strength markedly reduced human OATP and rat oatp activity. 6′,7′-Dihydroxybergamottin potently inhibited rat oatp3 and oatp1 (IC50, 0.28 μmol/L). Other furanocoumarins and bioflavonoids also reduced rat oatp3 activity. Grapefruit, orange, and apple juices decreased the fexofenadine area under the plasma concentration–time curve (AUC), the peak plasma drug concentration (Cmax), and the urinary excretion values to 30% to 40% of those with water, with no change in the time to reach Cmax, elimination half-life, renal clearance, or urine volume in humans. Change in fexofenadine AUC with juice was variable among individuals and inversely dependent on value with water. Conclusions Fruit juices and constituents are more potent inhibitors of OATPs than P-glycoprotein activities, which can reduce oral drug bioavailability. Results support a new model of intestinal drug absorption and mechanism of food-drug interaction. Clinical Pharmacology & Therapeutics (2002) 71, 11–20; doi: 10.1067/mcp.2002.121152