bluuebunny/crossref_metadata_2025 huggingface dataset:
Granulocytic Sarcoma of the Colon and Leukemic Infiltration of the Liver in a Patient Presenting with Hematochezia and Jaundice
Authors: Sevinc Alper , Buyukberber Suleyman , Camci Celalettin , Koruk Mehmet , Savas M. Cemil , Turk H. Mehmet , Sari Ibrahim , Buyukberber N. Mehmet
Published: July 2004

Granulocytic sarcoma (GS) is an extramedullary tumor composed of immature cells of the granulocytic series known to occur in patients with myelodysplastic syndrome, chronic myelogenous leukemia, or acute myelogenous leukemia (AML). Involvement of the gastrointestinal tract is relatively rare in GS. We present an extremely rare case of GS of the colon and liver infiltration in a 60-year-old male patient with AML presenting with jaundice and hematochezia and review the literature. It should be kept in mind that hematochezia may be due to colonic involvement of GS besides thrombocytopenia which is usually encountered in patients with AML.
Treatment of Early Diagnosed HCV Infection in Hemodialyzed Patients with Interferon-α. Treatment of Hepatitis C
Authors: Urbánek P. , Tesař V. , Procházková-Francisci E. , Lachmanová J. , Mareček Z. , Svobodník A.
Published: July 2004

Background: Acute and early diagnosed hepatitis C virus (HCV) infections are rare diagnoses. Patients on regular dialysis treatment (RDT) are at risk of acquiring HCV infection. Aims of the Study: (1) To determine the efficacy and safety of two-phase induction treatment of acute and early diagnosed HCV infections in patients on RDT, and (2) to establish the importance of serum HCV RNA testing at defined time points of treatment for the prediction of the therapeutic effect. Therapeutic Protocol: Antiviral treatment consisted of two different phases: phase A therapy was interferon (IFN)-α2b 10 million units (MU) s.c. administered daily for 21 days followed by phase B with IFN-α2b 3 MU s.c. administered 3 times weekly for 12 weeks. Results: (1) Efficacy of the treatment: A sustained virological response (SVR) was achieved in a total of 13/18 patients (72%). Safety: We did not observe any serious side effects of the treatment. The most pronounced side effect was the myelosuppression caused by IFN-α. (2) SVR prediction: Patients with negative serum HCV RNA at day 6 achieve SVR more frequently than those with positive HCV RNA at day 6 (p = 0.074). Conclusions: Treatment of acute and early diagnosed HCV infections in hemodialyzed patients is much more effective than treatment of chronic infection. Even relatively high doses of IFN at the beginning of therapy (10 MU daily) are tolerated well by the patients.
Procoagulant activity of bronchoalveolar lavage fluids taken from the site of tuberculous lesions
Authors: Selvaraj P , Venkataprasad N , Vijayan VK , Prabhakar R , Narayanan PR
Published: July 2004

We wanted to determine the procoagulant activity (PCA) of bronchoalveolar lavage fluids, in order to understand the macrophage-mediated lung injury at the site of tuberculous lesion. Alveolar lavage fluids taken from the site of a lesion (radiologically abnormal site (RAS)) and an unaffected site (radiologically normal site (RNS)) of active pulmonary tuberculosis (TB) patients (n = 7) and inactive (cured) patients (n = 9) were studied for their PCA producing potential. The observed results were not significant using Mann-Whitney test, and thus all increases/decreases reported below are trends/tendencies only. An increased PCA was seen in 4 out of 7 cell-free lavage supernatants of active-TB taken from the site of lesion (RAS), compared to only 1 out of 9 in inactive-TB. The PCA producing potential of the alveolar macrophages of RAS and RNS of active-TB patients was enhanced when the alveolar macrophages were co-cultured with autologous peripheral blood lymphocytes under in vitro condition. Stimulation with purified protein derivative (PPD) of M. tuberculosis showed a variable (increased or decreased) PCA production. Peripheral blood monocytes and total mononuclear cells (monocytes+lymphocytes) of active-TB patients stimulated with or without PPD showed increased PCA production, compared with normal individuals and inactive-TB patients. The present study suggests that increased production of PCA by the alveolar macrophages, in collaboration with lymphocytes and other cells at the site of tuberculous lesions will result in fibrin formation. The deposition of fibrin in the alveoli may lead to further lung injury.
Coughing frequency in patients with persistent cough: assessment using a 24 hour ambulatory recorder
Authors: Hsu JY , Stone RA , Logan-Sinclair RB , Worsdell M , Busst CM , Chung KF
Published: July 2004

Cough is an important symptom of many respiratory disorders. We determined the frequency and diurnal variation of cough in normal subjects and in patients with asthma or with persistent cough of unknown cause. We used a portable, solid-state, multiple-channel recorder to record cough sounds over a 24 h period. The audio-signal was recorded from a unidirectional microphone strapped over the chest wall, and electromyographic (EMG) signals from the lower respiratory muscles were simultaneously registered with surface electrodes. The recorded digital data were examined on an IBM-compatible computer, and the typical signals induced by cough (as assessed by voluntary or experimentally-induced cough) were counted. In 12 normal subjects, only 0-16 coughs were recorded over 24 h. In 21 stable asthmatics with a history of chronic cough ("asthma") the median number was 282 (ranges: 45-1,577), and in 14 patients with the predominant symptom of daily dry coughs ("chronic coughers") the median number was 794 (64-3,639). In both groups of patients, there was a diurnal variation of coughs, such that the least numbers occurred between 2 and 5 a.m. (< 3% of total). In the astham group, there was no significant correlation between forced expiratory volume in one second (FEV1) (% predicted) or diurnal variation of peak expiratory flow and cough frequency. In the chronic coughers, there was a significant correlation between daytime cough numbers and daytime cough symptoms scores but not for the night-time values. Our data show that cough frequency is not determined by the severity of asthma in relatively stable asthmatics on inhaled steroids, and is reduced during sleep in both asthmatics and chronic cough patients. This portable cough recorder may be useful in the assessment of drug therapy for chronic cough.
The levels of clarithromycin and its 14-hydroxy metabolite in the lung
Authors: Honeybourne D , Kees F , Andrews JM , Baldwin D , Wise R
Published: July 2004

Clarithromycin is a new macrolide that has a longer half-life than erythromycin and is claimed to reach higher tissue concentrations. We aimed to investigate whether, following oral administration, the drug and its 14-hydroxy metabolite reach levels in lung tissue that are likely to be clinically effective against common respiratory pathogens. Ten patients undergoing diagnostic bronchoscopy received seven doses of clarithromycin, 500 mg b.i.d. orally. Bronchoscopy was performed at a mean time of 4.25 h after the last dose. At bronchoscopy, bronchial biopsies and bronchoalveolar lavage were performed. Clarithromycin and its 14-OH metabolite were measured in serum, bronchial biopsies, epithelial lining fluid (ELF) and alveolar cells. Mean levels of clarithromycin were 4.0 mg.l-1 in serum, 16.8 mg.kg in bronchial biopsies, 20.5 mg.l-1 in ELF and 372.7 mg.l-1 in alveolar cells. The equivalent levels of 14-OH metabolite were 0.7, 2.7, 1.9 and 38.6 mg.l-1, respectively. We conclude that there is considerable concentration of clarithromycin and its 14-OH metabolite in alveolar cells, and to a lesser extent in bronchial tissue and ELF; this implies efficacy against susceptible organisms at these sites.
Dry air- and hypertonic aerosol-induced bronchoconstriction and cellular responses in the canine lung periphery
Authors: Freed AN , Omori C , Hubbard WC , Adkinson NF
Published: July 2004

Dry air and hypertonic saline both create an osmotic stress to the airways, whilst dry air alone induces transient cooling of the airway mucosa. It is unclear whether these two stimuli lead to bronchoconstriction via the same mechanisms. We compared airflow- and hypertonic aerosol-induced bronchoconstriction (AIB and HIB, respectively) in the canine lung periphery, using a wedged bronchoscope to measure collateral system resistance (Rcs). Bronchoalveolar lavage (BAL) was used to examine changes in cells and mediators during AIB and HIB. We found that: 1) peripheral airways are not refractory to either dry air or hypertonic aerosols, and do not exhibit cross-refractoriness to these stimuli; 2) differences in strength of stimulus can alter the magnitude but not the time course of HIB; 3) within an individual, AIB and HIB are significantly correlated; 4) epithelial cells recovered in BAL fluid (BALF) are significantly elevated after AIB, and are similarly increased after HIB; 5) when compared to control, mediators recovered in BALF are significantly elevated after AIB but not HIB; 6) HIB is not altered by cyclo-oxygenase inhibition; and 7) lavage with hypertonic fluid does not affect the number of epithelial cells recovered, although the concentrations of some mediators are increased. We speculate that differences in cell and mediator profiles reflect differences in the time course of AIB and HIB that result from the modulation of temperature sensitive pathways that occurs during dry air, but not during hypertonic aerosol challenge.
Prognostic factors in lung cancer: tables and comments
Authors: Buccheri G , Ferrigno D
Published: July 2004

Prognostic factors (PF) have a pivotal role in Clinical Oncology. They are helpful in the selection of treatment, provide insights into the disease process and the therapeutic response, and are fundamental in the design of clinical trials or in the interpretation of data from the literature. The number of possibly useful PFs in lung cancer is large (certainly more than one hundred). This paper attempts to provide a comprehensive listing of PFs and other variables potentially associated with outcome of lung cancer. This is achieved using tables, where studies relevant to each PF are referenced in relationship to their results, statistical power, type of analysis, number of variables incorporated in multivariate tests, and cell type. Tables include the outcome of an extensive retrieval of the literature and indicate visually where much of the evidence resides for the contribution of a variable to prognosis. Each table is briefly discussed and systematically comprises one group of PFs. Among the many pinpointed, the best predictive models still belong to studies based on clinical and routine laboratory data. Recent researches have clarified the role of new PFs (such as the biological factors); others (e.g. quality of life measures, the serum content of acute phase reaction proteins or the pathological evidence of tumour neoangiogenesis) might be recognized as important in the future. Like infinity, the fate of the individual patient will never become a completely measurable entity. However, as the discovery of new PFs proceeds, the assessment of the future prospects for patients is becoming more reliable.
Late recurrence of Wegener's granulomatosis presenting as solitary upper lobe pulmonary mass
Authors: van der Werf TS , Stegeman CA , Meuzelaar KJ , Timens W
Published: July 2004

Recurrent Wegener's granulomatosis (WG) was diagnosed in a 40 year old man presenting with a solitary mass in the right lung apex and with possible lymph node enlargement in the anterior mediastinum, resembling malignancy. Eight years previously, a first episode of WG involving the upper airways and kidneys, but not the lungs, had been successfully treated with prednisolone and cyclophosphamide, which could be stopped after 2 yrs. The antineutrophil cytoplasmic antibody titres (anti-protease 3), which had been very high during the first disease episode, failed to predict the recurrence.
The protective effect of vitamin C, vitamin E and selenium combination therapy on ethanol-induced duodenal mucosal injury
Authors: Koyuturk M , Bolkent S , Ozdil S , Arbak S , Yanardag R
Published: July 2004

In this study, the effect of a combination of vitamin C, vitamin E and selenium on ethanol-induced duodenal mucosal damage in rats was investigated morphologi-cally and biochemically. The duodenal mucosal injury was produced by oral administration of 1 mL of absolute ethanol to each rat. Animals received vitamin C (250 mg/kg), vitamin E (250 mg/kg) and selenium (0.5 mg/kg) for 3 days and absolute ethanol 1 hour after last antioxidant administration and were sacrificed 1 hour after absolute ethanol. Extreme degeneration in intestinal mucosa of rats given ethanol was observed morphologically. In addition, an increase in neuronal nitric oxide synthase immunoreactive areas was observed in the rats of the group given ethanol. On the other hand, a normal morphological appearance and a decrease in neuronal nitric oxide synthase immunoreactive areas were detected in the rats given ethanol+vitamin C+vitamin E+selenium. In the group to which ethanol was administered, an increase in serum cholesterol and a decrease in serum albumin levels were determined. On the other hand, in the group to which ethanol+vitamin C+vitamin E+selenium were administered, serum cholesterol value decreased, and the serum albumin level increased. As a result, we can say that the combination of vitamin C, vitamin E and selenium has a protective effect on ethanolinduced duodenal mucosal injury.
Reversal of P-gp mediated multidrug resistance in-vitro and in-vivo by FG020318
Authors: Chen Li-ming , Liang Yong-ju , Ruan Ji-wu , Ding Yan , Wang Xiu-wen , Shi Zhi , Gu Lian-Quan , Yang Xiao-ping , Fu Li-wu
Published: July 2004

Overexpression of P-glycoprotein (P-gp) by tumours results in multidrug resistance (MDR) to structurally and functionally unrelated chemotherapeutic drugs. Combined therapy with MDR-related cytotoxins and MDR modulators is a promising strategy to overcome clinical MDR. This study was performed to explore the MDR reversal activity of a novel compound 2-[4-(2-pyridin-2-yl-vinyl) phenyl]-4,5-bis-(4-N,N-diethylaminophenyl)-1(H)-imidazole (FG020318) in-vitro and in-vivo. Tetrazolium (MTT) assay was used to evaluate the ability of FG020318 to reverse drug resistance in two P-gp-expressing tumour cell lines, KBv200 and MCF-7/adr. Intracellular doxorubicin accumulation was determined by fluorescence spectrophotometry in MCF-7/adr cell line. The effect of FG020318 on P-gp function was demonstrated by rhodamine 123 (Rh123) accumulation in KBv200 cells. KBv200 cell xenograft models were established to study the in-vivo effect of FG020318 on reversing MDR. FG020318 was not cytotoxic by itself against P-gp expressing KBv200 cells and MCF-7/adr cells and their parental drug-sensitive KB cells and MCF-7 cells. FG020318 could significantly increase the sensitivity of MDR cells to antitumour drugs including doxorubicin and vincristine in MCF-7/adr cells and KBv200 cells, respectively. It was much stronger than the positive control verapamil in reversal of MDR. FG020318 also increased the intracellular accumulation of doxorubicin in a concentration-dependent manner in MCF-7/adr cells, but did not affect the accumulation of doxorubicin in drug-sensitive MCF-7 cells. The Rh123 accumulation in resistant KBv200 cells was also increased by the addition of FG020318, but Rh123 accumulation was not affected by FG020318 in drug-sensitive KB cells. FG020318 potentiated the antitumour activity of vincristine to KBv200 xenografts and was an efficacious modulator in-vivo. Our results suggested that FG020318 was a highly potent, efficacious MDR modulator not only in-vitro but also in-vivo. The reversal of drug resistance by FG020318 was probably related to the increased anticancer drug accumulation and its inhibition of P-gp function of MDR tumour cells.
Calcium channel antagonists attenuate cross-sensitization to the rewarding and/or locomotor effects of nicotine, morphine and MK-801
Authors: Biala Grazyna , Weglinska Barbara
Published: July 2004

The present study focused on the evaluation of behavioural cross-sensitization, particularly in locomotor activities and conditioned rewarding effects, between nicotine and morphine, cocaine, amphetamine or MK-801. Nicotine (0.5 mg kg−1)-experienced mice manifested an enhanced locomotor response to morphine (5 mg kg−1) or MK-801 (0.3 mg kg−1). No cross-sensitization was observed between nicotine and amphetamine (2 mg kg−1) or cocaine (15 mg kg−1). Additionally, the L-type voltage-dependent calcium-channel antagonists, nimodipine and verapamil, but not diltiazem, at a dose of 20 mg kg−1 injected before morphine or MK-801 challenge, blocked the expression of this cross-sensitization. In the second test, an enhancement of morphine place conditioning in rats pre-exposed to nicotine (0.5 mg kg−1, injected daily for 5 days) was demonstrated. After two conditioning sessions, morphine (5 mg kg−1) induced a clear place preference only in animals that had previously received nicotine injections. The administration of nimodipine (10 and 20 mg kg−1), verapamil (10 and 20 mg kg−1) and diltiazem (10 and 20 mg kg−1) prior to nicotine dose-dependently prevented this sensitization to the rewarding effect of morphine produced by prior injections of nicotine. These findings support the hypothesis that similar neural calcium-dependent mechanisms are involved in the appetitive effects of nicotine and morphine and in the sensitized locomotor stimulant effects of nicotine and morphine or MK-801.
Lack of congruence between cysteine dioxygenase activity and S-carboxymethyl-l-cysteine S-oxidation activity in rat cytosol
Authors: Khan Samera , Mitchell Stephen C , Steventon Glyn B
Published: July 2004

The identity of the enzyme(s) responsible for the S-oxidation of the mucoactive drug S-carboxy-methyl-l-cysteine (SCMC) is unknown but the protein(s) are a susceptibility factor for a number of chronic degenerative diseases. The structural similarities between the amino acid l-cysteine and SCMC have raised the possibility that cysteine dioxygenase (CDO) may be responsible for this biotransformation reaction. Both CDO and SCMC S-oxygenase were found to require Fe2+ for enzymatic activity, and both enzyme activities were inhibited by Fe2+ and Fe3+ chelators. However, sulphydryl group modification of the enzymes resulted in the activation of the S-oxidation of SCMC but inhibition of the S-oxidation of l-cysteine. When the two enzyme activities were quantified in 20 female hepatic cytosolic fractions no linear correlation in the production of their respective metabolites was seen. The results of this investigation indicate that CDO is not responsible for the S-oxidation of SCMC in the rat.
Solid-phase synthesis and evaluation of libraries of substituted 4,5-dihydropyridazinones as vasodilator agents
Authors: Gouault Nicolas , Martin-Chouly Corinne A E , Lugnier Claire , Cupif Jean-François , Tonnelier Amaury , Feger Frédéric , Lagente Vincent , David Michèle
Published: July 2004

The solid-phase parallel preparation of a library of 4,5-dihydropyridazin-3(2H)-one derivatives substituted at position 6 with piperazinylmethyl or tetrahydroquinolinylmethyl groups and analogues (3) is reported. Polymer-supported γ-keto-δ-aminoesters prepared from Wang resin reacted with hydrazine or methylhydrazine to afford pyridazinones in good yields after a cyclization cleavage approach. We have evaluated these novel analogues and several compounds of other series (1, 2) for their vasorelaxant effect. Among the products tested, 3I and 3d proved to be efficacious and potent relaxant agents of the isolated rat aorta. Inhibitors of phosphodiesterase (PDE3), responsible for the breakdown of cyclic AMP in the vascular smooth muscle, are currently developed for cardiac heart failure because of their inotropic effect and coronary vasodilatation. We had expected that the vasodilatation induced by 3l, as efficient as reference PDE3 inhibitors, milrinone or CI-930, to be due to PDE3 inhibition. However 3I and 3d exhibited a low inhibitory effect against PDE3 isoenzyme activity. These compounds induced a significant vasorelaxation, which could be of therapeutic interest even if their mechanism of action remains to be determined.
Effect of lansoprazole and rabeprazole on tacrolimus pharmacokinetics in healthy volunteers with CYP2C19 mutations
Authors: Itagaki Fumio , Homma Masato , Yuzawa Kenji , Nishimura Masuhiro , Naito Shinsaku , Ueda Nobuhiko , Ohkohchi Nobuhiro , Kohda Yukinao
Published: July 2004

The aim of this study was to investigate the effects of the proton pump inhibitors (PPIs), lansoprazole and rabeprazole, on tacrolimus pharmacokinetics in healthy volunteers with mutations in the cytochrome P450 (CYP) 2C19 gene (CYP2C19). An open-label crossover study was performed with 19 healthy subjects. Tacrolimus (2 mg) was administered orally with and without lansoprazole (30 mg per day for 4 days) or rabeprazole (10 mg per day for 4 days). Blood concentrations of tacrolimus were determined before and 1, 2, 4 and 8 h after dosing. Genotyping for CYP2C19 was conducted by a polymerase chain reaction-restriction fragment length polymorphism method. Coadministration of lansoprazole significantly decreased the oral tacrolimus clearance, resulting in an increase in the area under the blood concentration-time curve (AUC0–8) (control vs with lansoprazole: 29.7 ± 3.5 vs 44.1 ± 5.0 ng h mL−1, P<0.05). Large individual variation was observed in the effects of lansorazole on tacrolimus AUC0–8 owing to CYP2C19 genotype status. The percent change for tacrolimus AUC0–8 in subjects with and without CYP2C19 mutant alleles was 81% and 29%, respectively. Coadministration of rabeprazole also increased the mean AUC0–8 of tacrolimus, but the difference was not statistically significant. These observations suggest that drug interaction between tacrolimus and lansoprazole occurs in subjects with higher lansoprazole blood concentrations corresponding to CYP2C19 genetic status. In contrast, rabeprazole has minimal effect on tacrolimus pharmacokinetics regardless of CYP2C19 genotype status.
Lack of effect of proteinase-activated receptor-2 (PAR-2) deletion on the pathophysiological changes produced by lipopolysaccharide in the mouse: comparison with dexamethasone
Authors: Kazerani Hamid Reza , Plevin Robin , Kawagoe Junichi , Kanke Toru , Furman Brian L
Published: July 2004

This study tested the hypothesis that activation of proteinase-activated receptor-2 (PAR-2) contributes towards the pathophysiology of lipopolysaccharide (LPS)-induced shock in the mouse. The effects of LPS on plasma glucose, biochemical markers of hepatic, renal and pancreatic exocrine function and lung content of myeloperoxidase (MPO) were examined in homozygous PAR-2 knockout mice (PAR-2 -/-) and genetically equivalent, homozygous PAR-2 +/+ mice. The effect of LPS was also examined in normal mice receiving dexamethasone (10 mg kg−1, i.p.) or saline as a positive control. At six hours after intraperitoneal injection, LPS (40 mg kg−1) produced an increase in rectal temperature, hypoglycaemia and elevations in serum concentrations of alanine aminotransferase (ALT), creatinine and lipase, as well as an increase in lung MPO content. Dexamethasone treatment reduced LPS-induced hypoglycaemia and elevation of serum ALT concentrations but did not modify elevations in serum creatinine and lipase concentrations or the increase in lung MPO content. The changes in serum concentrations of glucose, ALT, creatinine and lipase produced by LPS in PAR-2 -/- mice were not different from those seen in wild-type or PAR-2 +/+ mice. These data suggest that activation of PAR-2 may not play a pivotal role in LPS-induced multi-organ dysfunction.
Comparative assessment of ocular tissue distribution of drug-related radioactivity after chronic oral administration of 14C-levofloxacin and 14C-chloroquine in pigmented rats
Authors: Tanaka Makoto , Takashina Hideo , Tsutsumi Shuichiro
Published: July 2004

Fluoroquinolones have been reported to have a high affinity for melanin. The ocular tissue distribution and accumulation of radioactivity was compared after repeated oral administration of 14C-levofloxacin and 14C-chloroquine at daily doses of 20 mg (0.054 mmol) kg−1 and 28 mg (0.054 mmol) kg−1, respectively, in pigmented rats for 84 days. The mean serum level at 24 h following each dose of 14C-levofloxacin was almost constant in the range of 0.33–0.45 nmol equiv mL−1 after the 14th dose and thereafter. The melanin-containing ocular tissues, such as iris ciliary body and stratum pigment chorioides sclera, showed a much higher concentration of radioactivity than other non-pigmented ocular tissues. The respective concentration in iris ciliary body and stratum pigment chorioides sclera after the 1st dose was 126.47 and 74.91 nmol equiv g−1, and gradually increased with increasing dose number, reaching 1261.81 and 447.45 nmol equiv g−1 after the 84th dose, which was ca. 10 and 6 times higher, respectively, than after the 1st dose. The mean serum level following each dose of 14C-chloroquine was almost constant in the range 0.51–0.87 nmol equiv mL−1 after the 7th dose and thereafter. The respective concentration in iris ciliary body and stratum pigment chorioides sclera after the 1st dose was 572.10 and 709.41 nmol equiv g−1, and gradually increased with increasing dose number, reaching 33 317.92 and 12 322.90 nmol equiv g−1 after the 84th dose, which was ca. 58 and 17 times higher, respectively, than after the 1st dose. The concentration in aqueous humour, cornea, lens, vitreous body and retina after the 84th dose was 1.84, 6.33, 0.48, 5.60 and 11.42 nmol equiv g−1 for 14C-levofloxacin and 18.84, 264.99, 27.26, 158.43 and 1020.89 nmol equiv g−1 for 14C-chloroquine (ca. 10, 42, 57, 28 and 89 times higher, respectively, than for 14C-levofloxacin). Especially, the concentration in the retina was markedly higher after 14C-chloroquine administration than after 14C-levofloxacin administration. The concentration and the extent of accumulation of radioactivity not only in melanin-containing ocular tissues but also in other non-pigmented ocular tissues, such as retina, after chronic oral administration of 14C-levofloxacin once daily for 84 days were much lower than those after multiple dosing with 14C-chloroquine under the same conditions. These results indicate that levofloxacin would have a much lower risk for ocular toxicity than chloroquine after chronic dosing.
Concentration dependency of modulatory effect of amlodipine on P-glycoprotein efflux activity of doxorubicin — a comparison with tamoxifen
Authors: Darvari Ramin , Boroujerdi Mehdi
Published: July 2004

Modulators of P-glycoprotein (P-gp) can enhance or limit the permeability of a number of therapeutic agents that are considered substrates of this efflux pump protein. The modulatory effect of amlodipine (4-dihydropyridine calcium antagonist) on P-gp efflux activity has not been fully elucidated. We have studied the concentration dependency of its modulatory effect and compared it qualitatively with tamoxifen (a non-esteroid anti-estrogen). The investigation was conducted on transmembrane efflux of doxorubicin at a fixed concentration of 5 μm across a Caco-2 monolayer in the presence of various concentrations of amlodipine or tamoxifen. The maximum flux of doxorubicin from basolateral to apical (ba) occurred at 4.5 μm amlodipine and at 0.02 μm tamoxifen. At higher concentrations, the apical to basolateral (ab) flux and the net flux of doxorubicin (ba — ab) declined steadily in a concentration-dependent manner. We analysed the observed net flux data by fitting different mathematical models to the data. A composite sigmoidal Emax/Imax (stimulatory/inhibitory) model was found to be the most appropriate to define the system. The observed and calculated parameters supported the modulatory role of both compounds and clearly indicated that the stimulation and inhibition of transmembrane efflux occurred simultaneously in the presence of amlodipine or tamoxifen. It was concluded that amlodipine, similar to tamoxifen, modulated the transporter-dependent transmembrane flux of the P-gp substrate in a concentration-dependent manner.
Ethanol inhibits in-vitro metabolism of nifedipine, triazolam and testosterone in human liver microsomes
Authors: Patki Kiran C , Greenblatt David J , von Moltke Lisa L
Published: July 2004

Although extended exposure to ethanol induces CYP3A metabolism in-vivo, the acute effects of ethanol on CYP3A metabolism have not been fully evaluated in-vitro. We assessed the effect of ethanol on CYP3A-mediated biotransformation using human liver microsomes in-vitro with three prototypic CYP3A-mediated reactions: nifedipine to oxidized nifedipine, triazolam to its 1-hydroxy (1-OH TRZ) and 4-hydroxy (4-OH TRZ) metabolites, and testosterone to 6β-hydroxytestosterone (6β-OH TST). Ethanol inhibited metabolism of nifedipine (oxidized nifedipine IC50 3 mg dL−1, where the IC50 value is the inhibitor concentration corresponding to a 50% reduction in metabolite formation velocity), triazolam (1-OH TRZ IC50 1.1 mg dL−1, 4-OH TRZ IC50 2.7 mg dL−1) and testosterone (6β-OH TST IC50 2.4 mg dL−1). The inhibitory potency of ethanol was similar for the three substrates representing the three hypothetical CYP3A substrate categories. The IC50 values obtained were lower than clinically relevant blood alcohol concentrations. In conclusion, ethanol is an inhibitor of human CYP3A metabolism and may contribute to clinically important interactions.
Identification of P-glycoprotein substrates and inhibitors among psychoactive compounds — implications for pharmacokinetics of selected substrates
Authors: Abou El Ela Amal , Härtter Sebastian , Schmitt Ulrich , Hiemke Christoph , Spahn-Langguth Hildegard , Langguth Peter
Published: July 2004

The pharmacokinetics of antipsychotic drugs has become an integral part in understanding their pharmacodynamic activity and clinical effects. In addition to metabolism aspects, carrier-mediated transport, particularly secretion by ABC transporters, has been discussed as potentially relevant for this group of therapeutics. In this study, the psychoactive compounds perphenazine, flupentixol, domperidone, desmethyl clozapine, haloperidol, fluphenazine, fluvoxamine, olanzapine, levome-promazine, perazine, desmethyl perazine, clozapine, quetiapine and amisulpride were characterized in terms of P-glycoprotein (P-gp) affinity and transport. Experimental methods involved a radioligand displacement assay with [3H]talinolol as radioligand and transport — as well as transport inhibition — studies of the P-gp substrate [3H]talinolol across Caco-2 cell monolayers. In addition, the physicochemical descriptors log P and Δlog P were determined to test potential correlations between transporter affinity and lipophilicity parameters. All of the tested antipsychotics showed affinity to P-gp albeit their IC50 values (concentration of competitor that displaced 50% of the bound radioligand) differed by a factor exceeding 1000, when compared using the transport inhibition assay. From the group of P-gp substrates, amisulpride and fluphenazine were selected for in-vivo drug-drug interaction studies in rats to demonstrate the in-vivo relevance of the in-vitro findings. Compounds were administered by intraperitoneal injection either alone or in combination with 50 mg kg−1 ciclosporin. The concentration versus time profiles for both drugs were followed in serum as well as in brain tissues. Significant differences between the treatments with the antipsychotic alone versus the combination of antipsychotic with ciclosporin were found for amisulpride. The distribution of amisulpride to the brain was increased and systemic serum levels were likewise increased indicating decreased systemic clearance for the combination regimen. For fluphenazine, systemic levels with and without co-administraton of ciclosporin were comparable while higher brain-to-serum concentration ratios were found after co-administration of ciclosporin. The findings are explained on the basis of the limited contribution of P-gp-mediated transport to the elimination of fluphenazine and to a direct effect with respect to its distribution into the brain.
Parameters of drug antagonism: re-examination of two modes of functional competitive drug antagonism on intraocular muscles
Authors: Patil Popat N
Published: July 2004

There are two distinct kinetic functional pharmacological procedures by which the equilibrium affinity constant, KB, of a competitive reversible blocker is obtained. The classical method on an organ system requires the study of the parallel displacement of the agonist concentration-response curve in the presence of the blocker. In the second method, the agonist-evoked functional mechanical response is reduced to half by the blocker IC50 (the concentration required for 50% inhibition). In relation to these parameters the role of the ionization constant pKa and liposolubility log Pc or log D of blockers was examined. On the ciliary muscle from human eye, IC50/KB ratios for (±)-atropine, its quaternary analogue (±)-methylatropine, (-)-scopolamine, (±)-cyclopentolate, (-)-tropicamide, (±)-oxybutynin and pirenzepine were 15, 23, 4.4, 2.6, 1.66, 1.46 and 1.71, respectively. The ratios on the iris sphincter were comparable with those of ciliary muscle. When compared with large proportions of ionized molecules with water soluble properties of (±)-atropine and (±)-methylatropine, relatively high amounts of un-ionized and/or with greater partitioning of all other blockers in the lipoid barrier co-related well to low IC50/KB ratios, as predicted by the classical theory of competitive drug antagonism. It was hypothesized that due to receptor biophase access, the reduction of the mechanical response of the agonist by the highly ionized water-soluble antagonist at IC50 represented time-distorted “pseudo-equilibrium” estimation, where a higher concentration of the blocker was needed. On the other cholinergic effectors, like that of rat anococcygeus muscle or frog rectus abdominus muscle, IC50/KB ratios of respective blockers atropine or (+)-tubocurarine and hexamethonium were close to 1. Thus physicochemical properties, which affect the distribution coefficient log D and the tissue morphology (where asymmetric distribution of receptors may occur), appeared to be a critical factor in the analysis of the affinity parameters of the competitive reversible blocker. On the intraocular muscles, two functional pharmacological procedures for obtaining KB and IC50 values were not kinetically equivalent.
Comparative evaluation of the powder properties and compression behaviour of a new cellulose-based direct compression excipient and Avicel PH-102
Authors: Reus-Medina M , Lanz M , Kumar V , Leuenberger H
Published: July 2004

This study compares the compression behaviour of a new cellulose-based tableting excipient, hereinafter referred to as UICEL-A/102, and Avicel PH-102, a commercial direct compression excipient commonly referred to as microcrystalline cellulose (MCC). UICEL-A/102 shows the cellulose II lattice, while Avicel PH-102 belongs to the cellulose I polymorphic form. The median particle diameters of UICEL-A/102 and Avicel PH-102 fractions used in the study were 107 and 97 μm, respectively. Compared with Avicel PH-102, UICEL-A/102 was more dense; the relative poured and tapped densities were: 0.277 and 0.327 (vs 0.195 and 0.248 for Avicel PH-102), respectively. The true density, Ptrue, of the two materials was comparable (∼1.56g cm−3). The slopes of the in-die and out-of-die Heckel curves for Avicel PH-102 were steeper than for UICEL-A/102. The relative density versus applied pressure plot was in good agreement with the modified Heckel equation. The out-of-die and in-die minimal pressure susceptibility (χpmin) values calculated were 3.36 times 10−3 and 8.09 times 10−3 MPa−1 for UICEL-A/102 and 8.00 times 10−3 and 16.12 times 10−3 MPa−1 for Avicel PH-102, respectively. The elastic recovery profiles showed UICEL-A/102 to be more elastic than Avicel PH-102. In conclusion, UICEL-A/102 and Avicel PH-102 differ in their compression behaviour under pressure. The different polymorphic forms could provide a possible explanation.
A comparison of topical formulations for the prevention of human schistosomiasis
Authors: Cooper E , Iqbal A , Bartlett A , Marriott C , Whitfield P J , Brown M B
Published: July 2004

Recently, a dimeticone formulation has been shown to be effective at preventing Schistosoma cercariae infecting skin, while DEET (N,N-diethyl-m-toluamide), a highly effective insecticide, has been shown to have activity against cercariae. Seven formulations, 3 containing DEET, were prepared and applied to excised human skin in Franz cells for 1 h. Schistosoma cercariae were applied for 30 min at 1 and 24 h, and the number that penetrated the skin calculated (n = 9). DEET could not be incorporated into the dimeticone formulation, yet it remained the most effective at preventing cercarial penetration, both 1 and 24 h after application. The ointments that contained DEET did prevent penetration but their mode of action was due to the toxicity of DEET against the cercariae. The persistence of the protection afforded by the dimeticone formulation after washing suggests that the formulation may be interacting with the stratum corneum to prevent cercarial recognition of skin.
Inhibition of P-glycoprotein function by tea catechins in KB-C2 cells
Authors: Kitagawa Shuji , Nabekura Tomohiro , Kamiyama Shizu
Published: July 2004

We studied the effects of tea catechins, (-)-epicatechin (EC), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECG), and (-)-epigallocatechin gallate (EGCG) on the P-glycoprotein (P-gp) function in multidrug-resistant P-gp over-expressing KB-C2 cells. EC did not have any effects on cellular accumulation of P-gp substrates, rhodamine-123 and daunorubicin, but the other catechins increased the accumulation in the order of EGC<ECG<EGCG. The effects of EGCG were larger than those of verapamil and quercetin. Since these catechins inhibited the efflux of P-gp substrates, the elevation of substrate accumulation seemed to be induced by the inhibition of the efflux transporter. The results showed that the inhibitory effects of the catechins did not depend on their total hydrophobicity, but significantly depended on their chemical structure. The presence of the galloyl moiety on the C-ring markedly increased the n-octanol/PBS partition coefficients of the catechins and their activity on P-gp. On the other hand, the presence of the trihydric pyrogallol group as the B-ring decreased the partition coefficients but increased the activity on P-gp, compared with the action of the corresponding catechins with a dihydric catechol B-ring.
Inhibition of in-vitro simvastatin metabolism in rat liver microsomes by bergamottin, a component of grapefruit juice
Authors: Goff-Klein N Le , Klein L , Hérin M , Koffel J-C , Ubeaud G
Published: July 2004

Grapefruit juice can modify the pharmacokinetic parameters of many drugs, in particular simvastatin, an orally active cholesterol-lowering agent. The exact components in grapefruit juice responsible for drug interactions are not perfectly known. However, it seems that bergamottin, a furocoumarin derivative, is one of the main active components within grapefruit juice. The objective of this paper was to quantify and to characterize in-vitro the inhibitory effect of bergamottin on simvastatin metabolism by using rat and human liver microsomes. In rat liver microsomes, the incubation conditions (± NADPH) of bergamottin were found to influence its inhibiting capacity. In co-incubation with simvastatin, the Ki value (the equilibrium dissociation constant for the enzyme-inhibitor complex) was higher (Ki = 174±36 μm) than in pre-incubation (Ki =45±6 μm and 4±2μm, without and with NADPH, respectively). It thus seems that the pre-incubation of bergamottin (in particular with NADPH) increases its inhibiting capacity on simvastatin metabolism. Bergamottin metabolism study in rat liver microsomes showed the formation of two metabolites that were CYP-450 dependent. In contrast, in human liver microsomes, the incubation conditions of bergamottin did not influence its inhibiting capacity of simvastatin metabolism (Ki = 34±5 μm, Ki = 22±5 μm, Ki = 27±11 μm in co-incubation and pre-incubation without and with NADPH, respectively). In rat and man, bergamottin was found to be a mixed-type inhibitor of simvastatin hepatic metabolism. However, in rat, bergamottin was partially a mechanism-based inhibitor by involvement of either bergamottin alone or one of its metabolites. The results highlight the importance of validating in-vitro models to help verify the suitability of the in-vitro model for predicting the nature and degree of metabolic drug interactions.
Inhibition of human cytochromes P450 by components of Ginkgo biloba
Authors: von Moltke Lisa L , Weemhoff James L , Bedir Erdal , Khan Ikhlas A , Harmatz Jerold S , Goldman Peter , Greenblatt David J
Published: July 2004

The extraction, isolation and characterization of 29 natural products contained in Ginkgo biloba have been described, which we have now tested for their in-vitro capacity to inhibit the five major human cytochrome P450 (CYP) isoforms in human liver microsomes. Weak or negligible inhibitory activity was found for the terpene trilactones (ginkgolides A, B, C and J, and bilobalide), and the flavonol glycosides. However 50% inhibitory activity (IC50) was found at concentrations less than 10 μg mL−1 for the flavonol aglycones (kaempferol, quercetin, apigenin, myricetin, tamarixetin) with CYP1A2 and CYP3A. Quercetin, the biflavone amentoflavone, sesamin, as well as (Z,Z)-4,4′-(1,4-pentadiene-1,5-diyl)diphenol and 3-nonadec-8-enyl-benzene-1,2-diol, were also inhibitors of CYP2C9. The IC50 of amentoflavone for CYP2C9 was 0.019 μg mL−1 (0.035 μm). Thus, the principal components of Ginkgo biloba preparations in clinical use (terpene trilactones and flavonol glycosides) do not significantly inhibit these human CYPs in-vitro. However, flavonol aglycones, the biflavonol amentoflavone and several other non-glycosidic constituents are significant in-vitro inhibitors of CYP. The clinical importance of these potential inhibitors will depend on their amounts in ginkgo preparations sold to the public, and the extent to which their bioavailability allows them to reach the CYP enzymes in-situ.
β-Catenin signaling is required for neural differentiation of embryonic stem cells
Authors: Otero José Javier , Fu Weimin , Kan Lixin , Cuadra Adolfo E. , Kessler John A.
Published: July 2004

Culture of embryonic stem (ES) cells at high density inhibits bothβ-catenin signaling and neural differentiation. ES cell density does not influence β-catenin expression, but a greater proportion ofβ-catenin is targeted for degradation in high-density cultures. Moreover,in high-density cultures, β-catenin is preferentially localized to the membrane further reducing β-catenin signaling. Increasing β-catenin signaling by treatment with Wnt3a-conditioned medium, by overexpression ofβ-catenin, or by overexpression of a dominant-negative form of E-cadherin promotes neurogenesis. Furthermore, β-catenin signaling is sufficient to induce neurogenesis in high-density cultures even in the absence of retinoic acid (RA), although RA potentiates the effects of β-catenin. By contrast,RA does not induce neurogenesis in high-density cultures in the absence ofβ-catenin signaling. Truncation of the armadillo domain ofβ-catenin, but not the C terminus or the N terminus, eliminates its proneural effects. The proneural effects of β-catenin reflect enhanced lineage commitment rather than proliferation of neural progenitor cells. Neurons induced by β-catenin overexpression either alone or in association with RA express the caudal neuronal marker Hoxc4. However, RA treatment inhibits the β-catenin-mediated generation of tyrosine hydroxylase-positive neurons, suggesting that not all of the effects of RA are dependent upon β-catenin signaling. These observations suggest thatβ-catenin signaling promotes neural lineage commitment by ES cells, and that β-catenin signaling may be a necessary co-factor for RA-mediated neuronal differentiation. Further, enhancement of β-catenin signaling with RA treatment significantly increases the numbers of neurons generated from ES cells, thus suggesting a method for obtaining large numbers of neural species for possible use in for ES cell transplantation.
Combinatorial Fgf and Bmp signalling patterns the gastrula ectoderm into prospective neural and epidermal domains
Authors: Kudoh Tetsuhiro , Concha Miguel L. , Houart Corinne , Dawid Igor B. , Wilson Stephen W.
Published: July 2004

Studies in fish and amphibia have shown that graded Bmp signalling activity regulates dorsal-to-ventral (DV) patterning of the gastrula embryo. In the ectoderm, it is thought that high levels of Bmp activity promote epidermal development ventrally, whereas secreted Bmp antagonists emanating from the organiser induce neural tissue dorsally. However, in zebrafish embryos, the domain of cells destined to contribute to the spinal cord extends all the way to the ventral side of the gastrula, a long way from the organiser. We show that in vegetal (trunk and tail) regions of the zebrafish gastrula, neural specification is initiated at all DV positions of the ectoderm in a manner that is unaffected by levels of Bmp activity and independent of organiser-derived signals. Instead, we find that Fgf activity is required to induce vegetal prospective neural markers and can do so without suppressing Bmp activity. We further show that Bmp signalling does occur within the vegetal prospective neural domain and that Bmp activity promotes the adoption of caudal fate by this tissue.
Founder myoblasts and fibre number during adult myogenesis inDrosophila
Authors: Dutta Devkanya , Anant Sumita , Ruiz-Gomez Mar , Bate Michael , VijayRaghavan K.
Published: July 2004

We have examined the mechanisms underlying the setting of myotubes and choice of myotube number in adult Drosophila. We find that the pattern of adult myotubes is prefigured by a pattern of duf-lacZ-expressing myoblasts at appropriate locations. Selective expression of duf-lacZ in single myoblasts emerges from generalized,low-level expression in all adult myoblasts during the third larval instar. The number of founders, thus chosen, corresponds to the number of fibres in a muscle. In contrast to the embryo, the selection of individual adult founder cells during myogenesis does not depend on Notch-mediated lateral inhibition. Our results suggest a general mechanism by which multi-fibre muscles can be patterned.
Move it or lose it: axis specification in Xenopus
Authors: Weaver Carole , Kimelman David
Published: July 2004

A long-standing question in developmental biology is how amphibians establish a dorsoventral axis. The prevailing view has been that cortical rotation is used to move a dorsalizing activity from the bottom of the egg towards the future dorsal side. We review recent evidence that kinesin-dependent movement of particles containing components of the Wnt intracellular pathway contributes to the formation of the dorsal organizer,and suggest that cortical rotation functions to align and orient microtubules,thereby establishing the direction of particle transport. We propose a new model in which active particle transport and cortical rotation cooperate to generate a robust movement of dorsal determinants towards the future dorsal side of the embryo.