bluuebunny/crossref_metadata_2025 huggingface dataset:
Linezolid, a Novel Oxazolidinone Antibiotic: Assessment of Monoamine Oxidase Inhibition Using Pressor Response to Oral Tyramine
Authors: Antal Edward J. , Hendershot Pamela E. , Batts Donald H. , Sheu Wang‐Pui , Hopkins Nancy K. , Donaldson Kirsteen M.
Published: July 2003

The primary objective of this study was to compare the effects of oral linezolid with moclobemide and placebo on the pressor response to oral tyramine. Secondary objectives were to determine possible mechanisms of the effect based on changes in the pharmacokinetics of tyramine and to evaluate alternative methods for quantifying the pressor effect. Subjects received linezolid (625 mg bid orally), moclobemide (150 mg tid orally), or placebo for up to 7 days. Using the oral tyramine dose producing a > 30 mmHg increase in systolic blood pressure (SBP) (PD>30), a positive pressor response was defined as a PD> 30 index (pretreatment/treatment ratio of PD> 30) of ≥ 2. There were 8/10, 11/11, and 1/10 responders with linezolid, moclobemide, and placebo, respectively. Responses returned to baseline within 2 days of drug discontinuation. The ratio of mean greatest SBP and heart rate at the time of greatest SBP (GSBP/HR) increased linearly with tyramine dose both pretreatment and during treatment with linezolid and moclobemide. During treatment, responses to tyramine when subjects took linezolid or moclobemide were significantly different from placebo. Both drugs significantly decreased tyramine oral clearance compared with placebo. Urinary excretion of catecholamines and metabolites was consistent with MAOI activity of the drugs, but results were variable. The MAOI activity of linezolid is similar to that of moclobemide, a drug used clinically without food restrictions. Restrictions to normal dietary intake of tyramine‐containing foods are not warranted when taking linezolid.
Effects of Tolterodine, Trospium Chloride, and Oxybutynin on the Central Nervous System
Authors: Todorova Anelia , Vonderheid‐Guth Bettina , Dimpfel Wilfried
Published: July 2003

Antimuscarinic compounds are increasingly used to treat the symptoms of overactive bladder; however, their use is often restricted by peripheral adverse effects (AEs). On the other hand, data regarding their influence on the central nervous system (CNS) are limited. This randomized, single‐blind, parallel‐group quantitative‐topographical EEG (qEEG) study of clinical phase I investigates the potential CNS adverse effects of the three antimuscarinic drugs—tolterodine, oxybutynin, and trospium chloride—in comparison to placebo. Overall, 4 × 16 (total 64) young, healthy male volunteers were included in the study. The subjects were given either placebo or the clinically recommended daily doses of the drugs dispensed in three doses on a single day (tolterodine 2 mg bid and once placebo, total 4 mg/d; oxybutynin 5 mg tid, total 15 mg/d; and trospium chloride 15 mg tid, total 45 mg/d). The qEEG was recorded prior to and up to 4 hours after each intake of the trial medication (a total of 10 qEEG sessions) under three different conditions: at rest with eyes open, eyes closed, and under mental demand. The drug tolerability was subjectively evaluated by the volunteer and the investigator. In comparison to placebo (10% confidence interval), tolterodine and trospium chloride did not induce changes of the qEEG power in five of the six frequency bands (i.e., delta, alpha1, alpha2, beta1, and beta2). Isolated power decreases were only observed in the theta frequency band. In contrast, oxybutynin caused significant power reductions in four frequency bands (theta, alpha1, alpha2, and beta1; p < 0.01). The subjectively evaluated drug tolerability was comparable between all treatment groups, although differences in the AE occurrence existed, with the AE frequency being higher in the oxybutynin group. The results of this study support the findings that oxybutynin as a tertiary amine crosses the blood‐brain barrier, causing significant qEEG activity changes and more pronounced central adverse effects. Although tolterodine is also a tertiary amine, it shows limited effects on qEEG activity (i.e., slight theta power reductions), comparable to the effects of trospium chloride, a quarternary amine, which barely crosses the blood‐brain barrier. The minimal qEEG changes observed with tolterodine and trospium chloride reflect most probably a rebound message from the peripheral target organs. Prescription of oxybutynin thus implicates a higher risk of CNS side effects.
Effect of Age and Gender on the Safety, Tolerability, and Pharmacokinetics of BAY 12–9566 in Healthy Subjects
Authors: Lathia Chetan , Shah Anita , Sundaresan Pavur
Published: July 2003

The impact of age and gender on the single‐dose pharmacokinetics, safety, and tolerability of BAY 12–9566 was evaluated in healthy subjects. Volunteers were grouped according to age and gender (13 young males, 11 elderly males, and 12 elderly females) and then randomized in a 2:1 ratio to receive a single oral 50 mg dose of BAY 12–9566 or placebo. Serial plasma samples were collected up to 336 hours post dose and assayed for BAY 12–9566. Peak plasma concentration, time to reach peak plasma concentration, the area under the concentration‐time curve, oral clearance, volume of distribution, and elimination half‐life were calculated. BAY 12–9566 was well tolerated in all treatment groups, and no serious adverse events occurred during the study. Substantial age‐ or gender‐related differences were not observed for any of the pharmacokinetic parameters tested. Based on these pharmacokinetic and tolerability profiles, age‐ or gender‐related dose adjustments were not required for BAY 12–9566.
Steady‐State Pharmacokinetics and Tolerability of Modafinil Given Alone or in Combination with Methylphenidate in Healthy Volunteers
Authors: Hellriegel Edward T. , Arora Sanjay , Nelson Michael , Robertson Philmore
Published: July 2003

The potential for a pharmacokinetic (PK) drug‐drug interaction between modafinil and methylphenidate, each at steady state, was investigated in an open‐label, randomized, single‐period study in 32 healthy male and female volunteers. All subjects received modafinil once daily orally for 28 days (200 mg on Days 1–7 and 400 mg on Days 8–28). On Days 22 to 28, half of the subjects also received 20 mg of methylphenidate orally 8 hours after their modafinil dose. PK profiles of modafinil were obtained on Days 21 and 28 and compared between the two groups. There were no statistically significant differences between the treatment groups in the mean changes in PK parameters for modafinil. Parameters for its metabolites were also similar between the groups, and all treatments were well tolerated. The results indicate that administration of low‐dose methylphenidate 8 hours after treatment with modafinil does not appearto alterthe steady‐state pharmacokinetics of modafinil in healthy volunteers.
Pharmacokinetics of Norelgestromin and Ethinyl Estradiol from Two Consecutive Contraceptive Patches
Authors: Abrams Larry S. , Skee Ms. Donna M. , Wong Frankie A. , Anderson Ms. Nika J. , Leese Philip T.
Published: July 2003

The primary objective of this open‐label study was to determine the pharmacokinetics of norelgestromin (NGMN) and ethinyl estradiol (EE) following two consecutive applications of a contraceptive patch (ORTHO EVRA™/EVRA™). Twelve healthy women wore the first patch on their abdomen for 7 days and, after removal at 168 hours (day 7), wore a second patch for 10 days (i.e.,3 days beyond the intended 7‐day wear period). Blood samples were collected before and at various times up to 456 hours (day 19) after application of the first patch for analysis of NGMN and EE. Mean serum concentrations of NGMN and EE remained within the reference ranges, 0.6 to 1.2 ng/ml and 25 to 75 pg/ml, respectively, during the entire 7‐day wear period after application of the first patch and for 10 days after application of the second patch; reference ranges are based on studies with ORTHO‐CYCLEN ™/Cilest™. No patch detached spontaneously. No subject discontinued or experienced a serious adverse event.
Effect of Food and Food Composition on Alcohol Elimination Rates in Healthy Men and Women
Authors: Ramchandani Vijay A. , Kwo Paul Y. , Li Ting‐Kai
Published: July 2003

Several studies have evaluated the effect of food on alcohol pharmacokinetics; however, most studies have used oral alcohol administration, which cannot separate the influence of food on absorption from its influence on alcohol elimination. Alcohol clamping uses intravenous alcohol and provides a direct measure of the alcohol elimination rate (AER). Two studies, using alcohol clamping at 50 mg%, were conducted to investigate the effect of food and food composition on AER (g/h) in healthymenand women. In the first study, 20 subjects underwent two clamping sessions, one after a 12‐hour fast and another 1 hour after consuming a 530‐calorie breakfast. In the second study, 8 subjects underwent four clamping sessions: one after a 12‐hour fast and, in each of three “fed” sessions, 1 hour after a 550‐calorie high‐fat, high‐protein, or high‐carbohydrate breakfast. Comparison of AERs from the first study showed an average 25% increase following food compared to that following fasting. Men showed significantly higher AERs compared to women; however, the food effect was similar in both genders. In the second study, the AER showed a significant average 45% increase following the meal, regardless of composition, compared with that following fasting. These findings indicate that food intake results in increased alcohol elimination rates. The increase was similar for meals of different compositions, suggesting that the food effect is not due to specific interactions with meal constituents. Probable mechanisms for the increased alcohol elimination include food‐induced increases in hepatic blood flow and in the activity of alcohol‐metabolizing enzymes.
Omapatrilat: Neurohormonal and Pharmacodynamic Profile When Administered with Furosemide
Authors: Uderman Howard , Vesterqvist Ole , Manning James , Ferreira Irene , Delaney Carol , Liao Wei‐Chi
Published: July 2003

Pharmacodynamic effects of combination therapy with omapatrilat and furosemide were evaluated. Two groups of 13 healthy subjects each received furosemide 20 mg daily for 15 days coadministered with either placebo on days 6 to 15 or omapatrilat 10 mg on days 6 to 10 and 25 mg on days 11 to 15. In the omapatrilat group, urinary excretion of atrial natriuretic peptide increased, and greater blood pressure reductions were seen compared with placebo. Concomitant omapatrilat treatment did not affect the acute diuresis, natriuresis, and kaliuresis observed with chronic administration of furosemide. Neither effective renal plasma flow nor glomerular filtration rate changed in either treatment group. No clinically significant safety issues were observed. Daily coadministration of omapatrilat 10 or 25 mg with furosemide 20 mg does not affect the pharmacodynamics of furosemide at steady state.
Effect of Rofecoxib on the Pharmacokinetics of Chronically Administered Oral Contraceptives in Healthy Female Volunteers
Authors: Schwartz Jules I. , Wong Peggy H. , Porras Arturo G. , Ebel David L. , Hunt Thomas R. , Gertz Barry J.
Published: July 2003

The effect of rofecoxib, a highly selective cyclooxygenase (COX)‐2 inhibitor, on the pharmacokinetics of ethinyl estradiol (EE) and norethindrone (NET), two common components of a combination oral contraceptive product, was examined. A double‐blind, two‐period crossover study was conducted in 18 healthy women who received ORTHO‐NOVUM® 1/35, a combination of EE (35 μg) and NET (1 mg), concurrently for 14 days with either 175 mg rofecoxib or matching placebo during two consecutive menstrual cycles. Plasma was sampled for EE, NET, sex hormone binding globulin (SHBG), and albumin. The AUC0–24 h geometric mean ratio (GMR: rofecoxib/placebo) with corresponding 90% confidence interval (CI) of EE and NET was 1.13 (1.06, 1.19) and 1.18(1.13,1.24), respectively. The Cmax GMR of EE and NET was 1.06 (0.98, 1.16) and 1.04 (0.99, 1.09), respectively. In each case, the 90% CIs satisfied the predefined bioequivalence limits of (0.80, 1.25). Measures of SHBG and albumin and routine clinical and laboratory safety parameters showed no clinically meaningful changes. The addition of rofecoxib to the oral contraceptive was not associated with any clinically important changes in EE or NET pharmacokinetics and thus would not be anticipated to influence the efficacy of this contraceptive regimen.
Effect of Calcineurin Inhibitor Therapy on P‐gp Expression and Function in Lymphocytes of Renal Transplant Patients: A Preliminary Evaluation
Authors: Parasrampuria Dolly A. , Lantz Marianne V. , Birnbaum Jytte L. , Vincenti Flavio G. , Benet Leslie Z.
Published: July 2003

Cyclosporine and tacrolimus are substrates and potent inhibitors of the multidrug transporter, P‐glycoprotein, in vitro. The authors have investigated the effect of chronic therapy with these and other immunosuppressive drugs on the expression and function of P‐glycoprotein in T lymphocytes. Using a P‐gp antibody, the authors studied the level of expression of P‐gp in CD4 and CD8 T cells over a period of time in renal transplant patients. For comparison, a group of healthy volunteers and patients who did not receive any calcineurin inhibitors but were maintained on mycophenolate mofetil was included. The P‐gp expression on lymphocytes from these two groups remained constant (over several months' time). However, patients who were started on tacrolimus or cyclosporine had an initial decline in expression of P‐gp on CD4 T cells. Patients who were initiated on calcineurin therapy on day 1 posttransplant also had a decrease in expression of P‐gp on CD4 T lymphocytes. This preliminary analysis suggests that the calcineurin inhibitors might be modulating the expression and function of transporters in lymphocytes, thus changing not only the drug concentration but also the apparent efficacy of these drugs. Further understanding and elucidation of such effects would be important in understanding the relationship between pharmacokinetics and pharmacodynamics of these and other drugs, especially for immunosuppressive and anti‐AIDS therapy.
Steady‐State Pharmacokinetics and Tolerability of Modafinil Administered Alone or in Combination with Dextroamphetamine in Healthy Volunteers
Authors: Hellriegel Edward T. , Arora Sanjay , Nelson Michael , Robertson Philmore
Published: July 2003

The potential for a drug‐drug interaction between modafinil and dextroamphetamine, each at steady state, was investigated in an open‐label, randomized, single‐period study in 32 healthy male and female volunteers. All subjects received modafinil orally once daily for 28 days (200 mg on Days 1–7; 400 mg on Days 8–28). On Days 22 to 28, half of the subjects also received dextroamphetamine (20 mg) orally 7hours after modafinil. Samples for pharmacokinetic (PK) profiling were obtained on Days 21 and 28. The mean changes in PK parameters for modafinil and its two circulating metabolites between the two groups were not statistically significantly different, except Cmax for modafinil acid. Adverse events obtained in the two groups were similar and mild or moderate in nature. The results indicate that administration of low‐dose dextroamphetamine in this dosing regimen does not alterthe steady‐state pharmacokinetics of modafinil. The combination has a similar tolerability profile as modafinil alone.
Impairment of Ciprofloxacin Absorption by Calcium Polycarbophil
Authors: Kato Ryuji , Ueno Kazuyuki , Imano Hideki , Kawai Masayuki , Kuwahara Shiro , Tsuchishita Yoshimasa , Yonezawa Emi , Tanaka Kazuhiko
Published: July 2003

The effect of calcium polycarbophil on the absorption of ciprofloxacin, a broad‐spectrum antibacterial agent, was evaluated in an in vitro and in vivo study. In the in vitro study, the release of ciprofloxacin from the cellulose membrane in the presence or absence of metal cations was measured using the dissolution test procedure. In the in vivo study, male ST Wistar rats and male volunteers were employed. First, 20 mg/kg of ciprofloxacin alone (Rat Study 1) or 20 mg/kg of ciprofloxacin in combination with 64 mg/kg of calcium chloride (Rat Study 2) was administered orally to 3 rats. Second, a volunteer study was employed and a randomized crossover design with two phases was used. In one phase, volunteers received 400 mg of ciprofloxacin alone (Study 1); in the other phase, they received 400 mg of ciprofloxacin and 1200 mg of fine calcium polycarbophil granules concomitantly (Study 2). The plasma and serum concentrations of ciprofloxacin were measured by high‐performance liquid chromatography. The release of ciprofloxacin from the cellulose membrane in the presence of aluminum, calcium, or iron ions was slower than that in the absence of these metal ions. The AUC0–4 and Cmax in Rat Study 2 were lowerthan those respective values in Rat Study 1. AUC0–4 was approximately 60% lower in Rat Study 2 than Rat Study 1. In the volunteer study, the AUC0–12 and Cmax in Study 2 were lower than those respective values in Study 1. In particular, AUC0–12 was approximately 50% lower in Study 2 than in Study 1. These findings suggest that when ciprofloxacin and calcium polycarbophil were coadministered concomitantly, a decrease of ciprofloxacin absorption was observed, and this action was caused by the formation of chelate complexes. Therefore, it seems clear that we should avoid the concomitant administration of ciprofloxacin and calcium polycarbophil.
Bioequivalence Testing for Locally Acting Gastrointestinal Products: What Role for Gamma Scintigraphy?
Authors: Wilding Ian
Published: July 2003

Bioequivalence testing for locally acting gastrointestinal products is a challenging issue for both the pharmaceutical industry and the global regulatory authorities. It is widely accepted that for medicinal products not intended to be delivered into the systemic circulation, pharmacokinetic bioavailability cannot be used. However, it is becoming increasingly accepted that local availability may be assessed, where appropriate, by approaches that qualitatively reflect the presence of the active substance at the site of action. These methods must be specifically chosen for that combination of active substance and route of drug delivery. This paper argues for the use of gamma scintigraphy as a validated measure of local availability and bioequivalence for topically acting products administered to the gastrointestinal tract by the oral and rectal route.
Effect of Estrogen Treatment and Vitamin D Status on Differing Bioavailabilities of Calcium Carbonate and Calcium Citrate
Authors: Heller Howard J. , Poindexter John R. , Adams‐Huet Beverley
Published: July 2003

The authors hypothesized that estrogen treatment or vitamin D status may affect the bioavailability of two common calcium supplements differently. Using data derived from a recent trial in 25 postmenopausal women, the authors found that AAUC of serum calcium after subtraction of placebo was significantly higher after calcium citrate (median, 0.85; 25th to 75th percentile, 0.70 to 3.15) than after calcium carbonate (0.25; −0.58 to 1.00) in non‐estrogen‐treated patients. There was no difference in the bioavailability of calcium between the two calcium formulations in estrogen‐treated patients. Bioavailability was also significantly higher with the citrate salt for the subgroups with lower serum 25‐hydroxyvitamin D and higher serum 1,25‐dihydroxyvitamin D concentrations. In summary, bioavailability of calcium from the calcium carbonate product was more dependent on estrogen treatment and vitamin D status than that of calcium citrate. This may explain the variable results of reported calcium supplementation studies.
A Comparison of Two Dosing Regimens of Succimer in Children with Chronic Lead Poisoning
Authors: Farrar Henry C. , McLeane Laura R. , Wallace Molly , White Kim , Watson Janine
Published: July 2003

There is limited information defining the optimal dosing regimen of succimer in the treatment of children with chronic lead poisoning. It is typically administered as a five day course of high dose therapy (1050 mg/m2/day) followed by 14 days of low dose therapy (700mg/m2/day). This study compared the effect on blood lead concentrations (BPb) of treatment with this standard regimen and an alternate regimen consisting of two courses of high dose therapy separated by one week. There were significant reductions in the mean BPb in both the standard (n=7) and alternate (n=4) treatment groups but there was not a significant difference between the groups. In the standard group, the BPb decreased from 33±4 to 27±6 mcg/dL. The BPb decreased from 33±6 to 23±4 mcg/dL in those treated with alternate therapy. This study suggests that two short courses of high dose therapy may be an acceptable alternative to standard succimer therapy. Because of the small size of this study, other studies are warranted.
Pharmacological Effects of HMG CoA Reductase Inhibitors Other Than Lipoprotein Modulation
Authors: White C. Michael
Published: July 2003

The HMG CoA reductase inhibitors reduce levels of low‐density lipoproteins, raise high‐density lipoproteins, and lower triglycerides. However, there are other pharmacological effects derived from HMG CoA reductase inhibitor therapy. Certain HMG CoA reductase inhibitors affect atherosclerotic plaque composition, endothelial function, platelet and clotting factors, and immune functioning. The unique extrahepatic pharmacological profile of agents in this class has not been fully characterized. All of the HMG CoA reductase inhibitors studied have improved endothelium‐dependent vasodilatation. Vascular smooth muscle proliferation is not significantly affected by pravastatin but is by the other agents. Of all the HMG CoA reductase inhibitors, cerivastatin is the most potent inhibitor of vascular smooth muscle proliferation. Pravastatin is the only agent proven to significantly reduce platelet‐thrombus formation and fibrinogen levels. Simvastatin has no effect on platelet‐thrombus formation or fibrinogen levels, while atorvastatin and lovastatin have been shown to increase fibrinogen in some studies. Plasminogen activator inhibitor‐1 levels are decreased by pravastatin, are not affected by atorvastatin, and are significantly increased by lovastatin and simvastatin. Pravastatin also has clinical benefits in transplant medicine as a result of inhibiting natural killer cell function, an effect that has not been explored with other HMG CoA reductase inhibitors.
Montelukast Dose Selection in 6‐ to 14‐Year‐Olds: Comparison of Single‐Dose Pharmacokinetics in Children and Adults
Authors: Knorr Barbara , Larson Patrick , Nguyen Ha H. , Holland Sherry , Reiss Theodore F. , Chervinsky Paul , Blake Kathryn , van Nispen Claar H. M. , Noonan Gertrude , Freeman Amanda , Haesen Rita , Michiels Nicole , Rogers J. Douglas , Amin Raju D. , Zhao Jamie , Xu Xin , Seidenberg Beth C. , Gertz Barry J. , Spielberg Stephen
Published: July 2003

Montelukast, an oral leukotriene‐receptor antagonist, has demonstrated efficacy and tolerability for the treatment of chronic asthma in adults. A once‐daily 10 mg dose (film‐coated tablet) was selected as the optimal adult dose based on dose‐ranging studies. Asthma is a similar disease and is treated with the same medications in children and adults. These observations suggested that a dose of montelukast in children providing overall drug exposure (i.e., montelukast plasma concentrations) similar to that of the 10 mg film‐coated tablet dose in adults would be efficacious, well tolerated, and obviate the need for separate dose‐ranging studies in children. Therefore, the dose of montelukast for 6‐ to 14‐ year‐old children was selected by identifying the chewable tablet dose of montelukast yielding a single‐dose area under the plasma concentration‐time curve (AUC) comparable to that achieved with the adult 10 mg film‐coated tablet dose. Based on this approach, which included dose normalization of data from several pediatric pharmacokinetic studies, a 5 mg chewable tablet dose of montelukast was selected for use in clinical efficacy studies in 6‐ to 14‐year‐old children with asthma.
A Pharmacokinetic Evaluation of Concomitant Administration of Linezolid and Aztreonam
Authors: Sisson Theresa Lasher , Jungbluth Gail L. , Hopkins Nancy K.
Published: July 2003

Linezolid, a new oxazolidinone antimicrobial agent, has a spectrum of activity encompassing a wide variety of Gram‐positive bacteria. The purpose of this study was to evaluate the pharmacokinetics of linezolid and aztreonam, an antimicrobial agent with selective activity against Gram‐negative bacteria, when given alone and in combination. Healthy subjects were randomized to receive single, 30‐minute intravenous infusions of (1) linezolid 375 mg, (2) aztreonam 1000 mg, and (3) linezolid 375 mg plus aztreonam 1000 mg in an open‐label, crossover manner. The only statistically significant differences observed with combination treatment relative to each drug alone were an increase in the maximum plasma concentration of linezolid (∼18%) and an approximate 7% decrease in the apparent elimination rate of aztreonam, neither of which are expected to be clinically significant. In healthy subjects, the combination of linezolid and aztreonam was safe and well tolerated compared with each agent used alone. Pharmacokinetic data demonstrate that coadministration of linezolid and aztreonam does not alter the disposition of either agent under single‐dose conditions. Therefore, it is not expected that a dose alteration of either agent will be necessary in a clinical setting.
Lack of Pharmacokinetic Interaction between Lansoprazole and Intravenously Administered Phenytoin
Authors: Karol Michael D. , Locke Charles S. , Cavanaugh John H.
Published: July 2003

The objective of this randomized, double‐blind, two‐period crossover study was to investigate whether concomitant steady‐state lansoprazole influences the pharmacokinetics of CYP2C9 substrates using single intravenously dosed phenytoin as a model substrate. In addition, the safety of concomitant administration of these two drugs was evaluated. Twelve healthy, nonsmoking, adult male subjects received 60 mg lansoprazole or placebo once daily for 9 days during each study period. On the morning of day 7, each subject received a single 250 mg intravenous phenytoin dose. There were no statistically significant differences between the two regimens for mean phenytoin Cmax or tmax. There was a minor (< 3%) but statistically significant difference between the two regimens for phenytoin AUC resulting from a very low intrasubject coefficient of variation (2.3%). The treatment and control mean plasma concentration phenytoin profiles were virtually super‐imposable. In conclusion, concomitant multidose lansoprazole administration is unlikely to have any clinically significant effect on the pharmacokinetics of CYP2C9 substrates in general or intravenous phenytoin specifically.
Effect of Food on the Pharmacokinetics of (‐) and (+) dOTC When Administered as an Oral Racemate
Authors: Smith Patrick F. , Forrest Alan , Adams John M. , Ballow Charles H.
Published: July 2003

The objective of this study was to evaluate the effect of food on the pharmacokinetics of racemic dOTC, a nucleoside analogue reverse transcriptase inhibitor, in adult male volunteers. Twelve healthy adult male subjects were enrolled in a randomized, open‐label, single‐dose crossover study. All were nonsmoking, within 15% of ideal body weight, and between 18 and 50 years of age. Subjects received single oral doses of 800 mg racemic dOTC, in random order, either fed or fasted. The meal given to fed subjects was the standard Food and Drug Administration high‐fat breakfast, and all subjects completed both study periods. Sixteen plasma samples for pharmacokinetic assessments were collected for 72 hours following dosing and assayed for (‐) and (+) dOTC concentrations. Area under the plasma concentration‐time curve (AUC), maximum observed plasma concentration (Cmax), and time to maximum concentration (tmax) were determined for each enantiomer by standard noncompartmental techniques. Statistical hypothesis testing was by Wilcoxon signed rank, and the two one‐sided tests procedure was used to determine bioequivalence between the fed and fasted study periods. The only effect of coadministration of racemic dOTC with food was a delay in time to peak concentration (tmax) of between 0.6 and 0.7 hours for both (‐) and (+) dOTC stereoisomers (p ≤ 0.02). Neither AUC (p ≥ 0.10) nor Cmax (p ≥ 0.35) differed significantly between the fed and fasted study periods for either (‐) or (+) dOTC. Both AUC and Cmax were equivalent between the fed and fasted study periods. It was concluded that there is no clinically significant effect of a high‐fat meal on the pharmacokinetics of either (‐) or (+) dOTC when administered orally as a racemic mixture.
A New Solution‐Based Intranasal Triamcinolone Acetonide Formulation in Patients with Perennial Allergic Rhinitis: How Does the Pharmacokinetic/Pharmacodynamic Profile for Cortisol Suppression Compare with an Aqueous Suspension‐Based Formulation?
Authors: Hochhaus Günther , González Mario A. , Dockhorn Robert J. , Shilstone Jonathan , Karafilidis John
Published: July 2003

The present study was undertaken to describe the pharmacokinetics of a new solution‐based intranasal triamcinolone acetonide formulation (Tri‐Nasaf®) in patients with perennial allergic rhinitis and to use a pharmacokinetic/pharmacodynamic (PK/PD) simulation approach to compare the potential effects on plasma cortisol with that of an aqueous suspension‐based nasal triamcinolone acetonide formulation (Nasacort® AQ). Data from an open‐label, randomized, three‐way crossover study in patients with perennial allergic rhinitis receiving three doses (100, 200, and 400 μg) of a nasal solution‐based triamcinolone acetonide formulation (Tri‐Nasal®) over 7 days were used to describe the pharmacokinetics of this formulation. Available literature data for a suspension‐based aqueous triamcinolone acetonide formulation (Nasacort® AQ) were used to describe its pharmacokinetic profile after similar single doses of 110, 220, and 440 μg. A PK/PD simulation approach was used to predict the anticipated cumulative cortisol suppression (CCS) of these two formulations. These simulations suggested a cortisol suppression of 8% to 16% for the single and steady‐ state doses of the solution‐based product. Similar CCS estimates were predicted for equivalent doses of the aqueous suspension‐based triamcinolone acetonide formulation with no difference between both formulations. Post hoc power analysis suggested that the predicted cortisol suppression is not likely to be significant for either preparation, including the clinically recommended doses of 200 and 220 μg of the solution‐based and suspension‐based formulations, respectively. In summary, based on the results of this PK/PD simulation, the plasma levels observed after nasal administration of the solution or the aqueous suspension are unlikely to induce a clinically relevant cortisol suppression, especially for the recommended dosing regimens of200 and 220 μg/day.
Altered fracture repair in the absence of MMP9
Authors: Colnot Céline , Thompson Zachary , Miclau Theodore , Werb Zena , Helms Jill A.
Published: July 2003

The regeneration of adult skeletal tissues requires the timely recruitment of skeletal progenitor cells to an injury site, the differentiation of these cells into bone or cartilage, and the re-establishment of a vascular network to maintain cell viability. Disturbances in any of these cellular events can have a detrimental effect on the process of skeletal repair. Although fracture repair has been compared with fetal skeletal development, the extent to which the reparative process actually recapitulates the fetal program remains uncertain. Here, we provide the first genetic evidence that matrix metalloproteinase 9 (MMP9) regulates crucial events during adult fracture repair. We demonstrate that MMP9 mediates vascular invasion of the hypertrophic cartilage callus, and that Mmp9-/- mice have non-unions and delayed unions of their fractures caused by persistent cartilage at the injury site. This MMP9- dependent delay in skeletal healing is not due to a lack of vascular endothelial growth factor (VEGF) or VEGF receptor expression, but may instead be due to the lack of VEGF bioavailability in the mutant because recombinant VEGF can rescue Mmp9-/- non-unions. We also found that Mmp9-/- mice generate a large cartilage callus even when fractured bones are stabilized, which implicates MMP9 in the regulation of chondrogenic and osteogenic cell differentiation during early stages of repair. In conclusion, the resemblance between Mmp9-/-fetal skeletal defects and those that emerge during Mmp9-/- adult repair offer the strongest evidence to date that similar mechanisms are employed to achieve bone formation, regardless of age.
Prickle 1 regulates cell movements during gastrulation and neuronal migration in zebrafish
Authors: Carreira-Barbosa Filipa , Concha Miguel L. , Takeuchi Masaki , Ueno Naoto , Wilson Stephen W. , Tada Masazumi
Published: July 2003

During vertebrate gastrulation, mesodermal and ectodermal cells undergo convergent extension, a process characterised by prominent cellular rearrangements in which polarised cells intercalate along the medio-lateral axis leading to elongation of the antero-posterior axis. Recently, it has become evident that a noncanonical Wnt/Frizzled (Fz)/Dishevelled (Dsh)signalling pathway, which is related to the planar-cell-polarity (PCP) pathway in flies, regulates convergent extension during vertebrate gastrulation. Here we isolate and functionally characterise a zebrafish homologue of Drosophila prickle (pk), a gene that is implicated in the regulation of PCP. Zebrafish pk1 is expressed maternally and in moving mesodermal precursors. Abrogation of Pk1 function by morpholino oligonucleotides leads to defective convergent extension movements, enhances the silberblick (slb)/wnt11 and pipetail (Ppt)/wnt5phenotypes and suppresses the ability of Wnt11 to rescue the slbphenotype. Gain-of-function of Pk1 also inhibits convergent extension movements and enhances the slb phenotype, most likely caused by the ability of Pk1 to block the Fz7-dependent membrane localisation of Dsh by downregulating levels of Dsh protein. Furthermore, we show that pk1interacts genetically with trilobite(tri)/strabismus to mediate the caudally directed migration of cranial motor neurons and convergent extension. These results indicate that, during zebrafish gastrulation Pk1 acts, in part, through interaction with the noncanonical Wnt11/Wnt5 pathway to regulate convergent extension cell movements, but is unlikely to simply be a linear component of this pathway. In addition, Pk1 interacts with Tri to mediate posterior migration of branchiomotor neurons, probably independent of the noncanonical Wnt pathway.
Tracking mesoderm induction and its specification to the hemangioblast during embryonic stem cell differentiation
Authors: Fehling Hans Jörg , Lacaud Georges , Kubo Atsushi , Kennedy Marion , Robertson Scott , Keller Gordon , Kouskoff Valerie
Published: July 2003

The hematopoietic and endothelial lineages derive from mesoderm and are thought to develop through the maturation of a common progenitor, the hemangioblast. To investigate the developmental processes that regulate mesoderm induction and specification to the hemangioblast, we generated an embryonic stem cell line with the green fluorescent protein (GFP) targeted to the mesodermal gene, brachyury. After the in vitro differentiation of these embryonic stem cells to embryoid bodies, developing mesodermal progenitors could be separated from those with neuroectoderm potential based on GFP expression. Co-expression of GFP with the receptor tyrosine kinase Flk1 revealed the emergence of three distinct cell populations,GFP-Flk1-, GFP+Flk1- and GFP+Flk1+ cells, which represent a developmental progression ranging from pre-mesoderm to prehemangioblast mesoderm to the hemangioblast.
The regulation of apoptosis by Numb/Notch signaling in the serotonin lineage ofDrosophila
Authors: Lundell Martha J. , Lee Hyung-Kook , Pérez Ernesto , Chadwell Linda
Published: July 2003

Apoptosis is prevalent during development of the central nervous system(CNS), yet very little is known about the signals that specify an apoptotic cell fate. In this paper, we examine the role of Numb/Notch signaling in the development of the serotonin lineage of Drosophila and show that it is necessary for regulating apoptosis. Our results indicate that when Numb inhibits Notch signaling, cells undergo neuronal differentiation, whereas cells that maintain Notch signaling initiate apoptosis. The apoptosis inhibitor p35 can counteract Notch-mediated apoptosis and rescue cells within the serotonin lineage that normally undergo apoptosis. Furthermore, we observe tumor-like overproliferation of cells in the CNS when Notch signaling is reduced. These data suggest that the distribution of Numb during terminal mitotic divisions of the CNS can distinguish between a neuronal cell fate and programmed cell death.
Smoothened translates Hedgehog levels into distinct responses
Authors: Hooper Joan E.
Published: July 2003

In the Drosophila wing, Hedgehog is made by cells of the posterior compartment and acts as a morphogen to pattern cells of the anterior compartment. High Hedgehog levels instruct L3/4 intervein fate, whereas lower levels instruct L3 vein fate. Transcriptional responses to Hedgehog are mediated by the balance between repressor and activator forms of Cubitus interruptus, CiR and CiA. Hedgehog regulates this balance through its receptor, Patched, which acts through Smoothened and thence a regulatory complex that includes Fused, Costal, Suppressor of Fused and Cubitus interruptus. It is not known how the Hedgehog signal is relayed from Smoothened to the regulatory complex nor how responses to different levels of Hedgehog are implemented. We have used chimeric and deleted forms of Smoothened to explore the signaling functions of Smoothened. A Frizzled/Smoothened chimera containing the Smo cytoplasmic tail (FFS) can induce the full spectrum of Hedgehog responses but is regulated by Wingless rather than Hedgehog. Smoothened whose cytoplasmic tail is replaced with that of Frizzled (SSF) mimics fused mutants, interfering with high Hedgehog responses but with no effect on low Hedgehog responses. The cytoplasmic tail of Smoothened with no transmembrane or extracellular domains(SmoC) interferes with high Hedgehog responses and allows endogenous Smoothened to constitutively initiate low responses. SmoC mimics costal mutants. Genetic interactions suggest that SSF interferes with high signaling by titrating out Smoothened, whereas SmoC drives constitutive low signaling by titrating out Costal. These data suggest that low and high signaling (1) are qualitatively different, (2) are mediated by distinct configurations of the regulatory complex and (3) are initiated by distinct activities of Smoothened. We present a model where low signaling is initiated when a Costal inhibitory site on the Smoothened cytoplasmic tail shifts the regulatory complex to its low state. High signaling is initiated when cooperating Smoothened cytoplasmic tails activate Costal and Fused, driving the regulatory complex to its high state. Thus, two activities of Smoothened translate different levels of Hedgehog into distinct intracellular responses.
blisteryencodesDrosophilatensin protein and interacts with integrin and the JNK signaling pathway during wing development
Authors: Lee Sung Bae , Cho Kyoung Sang , Kim Euysoo , Chung Jongkyeong
Published: July 2003

Tensin is an actin-binding protein that is localized in focal adhesions. At focal adhesion sites, tensin participates in the protein complex that establishes transmembrane linkage between the extracellular matrix and cytoskeletal actin filaments. Even though there have been many studies on tensin as an adaptor protein, the role of tensin during development has not yet been clearly elucidated. Thus, this study was designed to dissect the developmental role of tensin by isolating Drosophila tensin mutants and characterizing its role in wing development. The Drosophilatensin loss-of-function mutations resulted in the formation of blisters in the wings, which was due to a defective wing unfolding process. Interestingly, by1-the mutant allele of the gene blistery(by)-also showed a blistered wing phenotype, but failed to complement the wing blister phenotype of the Drosophila tensin mutants, and contains Y62N/T163R point mutations in Drosophila tensin coding sequences. These results demonstrate that by encodes Drosophila tensin protein and that the Drosophila tensin mutants are alleles of by. Using a genetic approach, we have demonstrated that tensin interacts with integrin and also with the components of the JNK signaling pathway during wing development; overexpression of by in wing imaginal discs significantly increased JNK activity and induced apoptotic cell death. Collectively, our data suggest that tensin relays signals from the extracellular matrix to the cytoskeleton through interaction with integrin, and through the modulation of the JNK signal transduction pathway during Drosophila wing development.
Microsurgical and laser ablation analysis of interactions between the zones and layers of the tomato shoot apical meristem
Authors: Reinhardt Didier , Frenz Martin , Mandel Therese , Kuhlemeier Cris
Published: July 2003

Plants exhibit life-long organogenic and histogenic activity in a specialised organ, the shoot apical meristem. Leaves and flowers are formed within the ring-shaped peripheral zone, which surrounds the central zone, the site of the stem cells. We have undertaken a series of high-precision laser ablation and microsurgical tissue removal experiments to test the functions of different parts of the tomato meristem, and to reveal their interactions. Ablation of the central zone led to ectopic expression of the WUSCHELgene at the periphery, followed by the establishment of a new meristem centre. After the ablation of the central zone, organ formation continued without a lag. Thus, the central zone does not participate in organogenesis, except as the ultimate source of founder cells. Microsurgical removal of the external L1 layer induced periclinal cell divisions and terminal differentiation in the subtending layers. In addition, no organs were initiated in areas devoid of L1, demonstrating an important role of the L1 in organogenesis. L1 ablation had only local effects, an observation that is difficult to reconcile with phyllotaxis theories that invoke physical tension operating within the meristem as a whole. Finally, regeneration of L1 cells was never observed after ablation. This shows that while the zones of the meristem show a remarkable capacity to regenerate after interference, elimination of the L1layer is irreparable and causes terminal differentiation.
The Snail-like CES-1 protein of C. elegans can block the expression of theBH3-only cell-death activator gene egl-1 by antagonizing the function of bHLH proteins
Authors: Thellmann Marion , Hatzold Julia , Conradt Barbara
Published: July 2003

The NSM cells of the nematode Caenorhabditis elegans differentiate into serotonergic neurons, while their sisters, the NSM sister cells, undergo programmed cell death during embryogenesis. The programmed death of the NSM sister cells is dependent on the cell-death activator EGL-1, a BH3-only protein required for programmed cell death in C. elegans, and can be prevented by a gain-of-function (gf) mutation in the cell-death specification gene ces-1, which encodes a Snail-like DNA-binding protein. Here, we show that the genes hlh-2 and hlh-3, which encode a Daughterless-like and an Achaete-scute-like bHLH protein, respectively, are required to kill the NSM sister cells. A heterodimer composed of HLH-2 and HLH-3, HLH-2/HLH-3, binds to Snail-binding sites/E-boxes in a cis-regulatory region of the egl-1 locus in vitro that is required for the death of the NSM sister cells in vivo. Hence, we propose that HLH-2/HLH-3 is a direct,cell-type specific activator of egl-1 transcription. Furthermore, the Snail-like CES-1 protein can block the death of the NSM sister cells by acting through the same Snail-binding sites/E-boxes in the egl-1 locus. In ces-1(gf) animals, CES-1 might therefore prevent the death of the NSM sister cells by successfully competing with HLH-2/HLH-3 for binding to the egl-1 locus.
nil per osencodes a conserved RNA recognition motif protein required for morphogenesis and cytodifferentiation of digestive organs in zebrafish
Authors: Mayer Alan N. , Fishman Mark C.
Published: July 2003

Digestive organ development occurs through a sequence of morphologically distinct stages, from overtly featureless endoderm, through organ primordia to, ultimately, adult form. The developmental controls that govern progression from one stage to the next are not well understood. To identify genes required for the formation of vertebrate digestive organs we performed a genetic screen in zebrafish. We isolated the nil per os (npo) mutation,which arrests morphogenesis and cytodifferentiation of the gut and exocrine pancreas in a primodial state. We identified the npo gene by positional cloning. It encodes a conserved protein, with multiple RNA recognition motifs, that is related to the yeast protein Mrd1p. During development npo is expressed in a dynamic fashion, functioning cell autonomously to promote organ cytodifferentiation. Antisense-mediated knockdown of npo results in organ hypoplasia, and overexpression of npo causes an overgrowth of gastrointestinal organs. Thus, npo is a gene essential for a key step in the gut morphogenetic sequence.
The maternal-effect genefutile cycleis essential for pronuclear congression and mitotic spindle assembly in the zebrafish zygote
Authors: Dekens Marcus P. S. , Pelegri Francisco J. , Maischein Hans-Martin , Nüsslein-Volhard Christiane
Published: July 2003

Embryos have been successfully used for the general study of the cell cycle. Although there are significant differences between the early embryonic and the somatic cell cycle in vertebrates, the existence of specialised factors that play a role during the early cell cycles has remained elusive. We analysed a lethal recessive maternal-effect mutant, futile cycle(fue), isolated in a maternal-effect screen for nuclear division defects in the zebrafish (Danio rerio). The pronuclei fail to congress in zygotes derived from homozygous fue mothers. In addition,a defect in the formation of chromosomal microtubules prevents mitotic spindle assembly and thus chromosome segregation in fue zygotes. However,centrosomal functions do not appear to be affected in fue embryos,suggesting this mutant blocks a subset of microtubule functions. Cleavage occurs normally for several divisions resulting in many anucleate cells, thus showing that nuclear- and cell division can be uncoupled genetically. Therefore, we propose that in mitotic spindle assembly chromosome-dependent microtubule nucleation is essential for the coupling of nuclear and cell division.