bluuebunny/crossref_metadata_2025 huggingface dataset:
Adjuvant Immunotherapy of Patients With High-Risk Melanoma Using Vaccinia Viral Lysates of Melanoma: Results of a Randomized Trial
Authors: Hersey Peter , Coates Alan S. , McCarthy William H. , Thompson John F. , Sillar Robert W. , McLeod Roderick , Gill P. Grantley , Coventry Brendon J. , McMullen Amanda , Dillon Haryana , Simes R. John
Published: October 2002

PURPOSE: Patients with high-risk melanoma treated by immunotherapy with vaccinia viral lysates were found in phase II studies to have improved survival compared with historical controls. We therefore elected to test this therapy in a phase III study.

PATIENTS AND METHODS: A prospective, randomized, multicenter trial to determine whether immunotherapy with a vaccine prepared from vaccinia melanoma cell lysates (VMCL) over a 2-year period after definitive surgery would improve relapse-free survival (RFS) and overall survival (OS) in patients with American Joint Committee on Cancer stage IIB and III melanoma compared with a control group treated only with surgery.

RESULTS: A total of 700 patients were randomized: 353 to VMCL and 347 to no immunotherapy. Seventy-seven percent had lymph node (LN) metastases and 66% had clinically detected LN metastases. Analysis on the basis of all eligible, randomized patients (n = 675) found, after a median follow-up period of 8 years, a median OS of 88 months in the control versus 151 months in the treated group (hazard ratio [HR], 0.81; 95% confidence interval [CI], 0.64 to 1.02; P = .068 by stratified univariate Cox analysis). At 5 and 10 years, survival rates for control and treated patients were 54.8% v 60.6% and 41% v 53.4%, respectively. Median RFS was 43 months in the control group compared with 83 months in the treated group (HR, 0.86; 95% CI, 0.7 to 1.07; P = .17). RFS at 5 years was 50.9% for the treated group and 46.8% for the control group. There were no selective benefits from the vaccine for particular subsets of patients.

CONCLUSION: Immunotherapy with VMCL was not associated with a statistically significant improvement in OS or RFS, with CIs not ruling out important gains from such treatment.
Uptake of lamivudine by rat renal brush border membrane vesicles
Authors: Takubo Takatoshi , Kato Toshihiro , Kinami Junji , Hanada Kazuhiko , Ogata Hiroyasu
Published: October 2002

Uptake of lamivudine, a nucleoside analogue antiviral agent, by brush border membrane vesicles (BBMV) prepared from rat renal cortex was investigated. Initial uptake of lamivudine by BBMV was stimulated in the presence of an outward pH gradient. Determination of the kinetic parameters of the initial uptake yielded apparent Km and Vmax values of 2.28 mM and 1.56 nmol (mg protein)−1 (20 s)−1, respectively. The pH-driven uptake of lamivudine was inhibited by organic cations such as trimethoprim and cimetidine. The inhibitory effect of trimethoprim on lamivudine uptake was competitive, with an apparent Ki of 27.6 μM. The uptake of lamivudine was also inhibited by nitrobenzylthioinosine, a representative inhibitor of nucleoside transport, and by other nucleoside analogues, such as azidothymidine and dideoxycytidine, that are excreted by renal tubular secretion. These findings suggest that efflux of lamivudine at the brush border membrane of renal tubular epithelium is mediated by an H+/lamivudine antiport system, which may correspond to the H+/organic cation antiport system, and that this system is also involved in the renal secretion of other nucleoside analogues.
Microemulsion formulation of clonixic acid: solubility enhancement and pain reduction
Authors: Lee Jung-Mi , Park Kyung-Mi , Lim Soo-Jeong , Lee Mi-Kyung , Kim Chong-Kook
Published: October 2002

Clonixic acid is currently marketed as a salt form because of its poor water-solubility. However, the commercial dosage form causes severe pain after intramuscular or intravenous injection. To improve the solubility of clonixic acid and to reduce pain on injection, clonixic acid was incorporated into oil-in-water microemulsions prepared from pre-microemulsion concentrate composed of varying ratios of oil and surfactant mixture. As an oil phase for drug incorporation, up to 14% castor oil could be included in the pre-microemulsion concentrate without a significant increase in droplet size. Both drug contents and droplet size increased as the weight ratio of Tween 20 to Tween 85 decreased. Taken together, when microemulsions were prepared from pre-microemulsion concentrate composed of 5:12:18 weight ratio of castor oil:Tween 20:Tween 85, clonixic acid could be incorporated at 3.2 mg mL−1 in the micro-emulsion with a droplet size of less than 120 nm. The osmotic pressure of this microemulsion was remarkably lower than the commercial formulation, irrespective of the dilution ratios. The rat paw-lick test was used to compare pain responses among formulations. The microemulsion formulation significantly reduced the number of rats licking their paws as well as the total licking time, suggesting less pain induction by the microemulsion formulation. The pharmacokinetic parameters of clonixic acid after intravenous administration of the clonixic acid microemulsion to rats were not significantly different from those of the commercial formulation, lysine clonixinate. The present study suggests that microemulsion is an alternative formulation for clonixic acid with improved characteristics.
Evaluation of increased bioavailability of tacrolimus in rats with experimental renal dysfunction
Authors: Okabe Hiromi , Yano Ikuko , Hashimoto Yukiya , Saito Hideyuki , Inui Ken-ichi
Published: October 2002

The effects of renal failure on the hepatic and intestinal extraction of tacrolimus were evaluated to examine the mechanisms for the increased bioavailability of this drug in cisplatin-induced renal failure model rats. Tacrolimus extractions in the liver and intestine were evaluated by intravenous, intraportal and intraintestinal infusion. The intestinal metabolism and absorption rate were estimated by incubating the isolated intestine with drug solution and by an in situ loop method, respectively. Blood concentrations of tacrolimus following the intraintestinal infusion were significantly increased in rats with renal failure compared with those in normal rats. The blood concentration of tacrolimus during intraportal infusion in rats with renal failure showed non-linearity against dose, and was increased as compared with that in normal rats. The intestinal metabolism was not altered, but the absorption rate was significantly increased in the intestine from rats with renal dysfunction. These results suggest that the hepatic metabolism of tacrolimus is impaired in rats with renal failure, and that the accelerated absorption rate in the intestine in renal dysfunction is followed by partial saturation of hepatic extraction, which may be one of the mechanisms of increased bioavailability of tacrolimus.
Pharmacokinetics of ABT-773, a new semi-synthetic ketolide in neutropenic lung-infected mice: a population approach
Authors: Xuan Dawei , Ye Min , Kim Myo , Nightingale Charles H , Nicolau David P
Published: October 2002

ABT-773 is an investigational ketolide antimicrobial agent with an in-vitro bactericidal activity against macrolide-susceptible and -resistant Streptococcus pneumoniae. The pharmacokinetics of this drug candidate were evaluated in lung-infected (108 CFU mL−1 starting inoculum) mice following a single dose (25, 50, 100 or 200 mg kg−1) oral administration as a solution in 10 % of 95% ethanol and 90% of 0.1 M pH 6.5 phosphate buffer solution. Serum ABT-773 concentrations were measured using a validated HPLC assay with fluorescence detection (excitation at 324 nm and emission at 364 nm). Population pharmacokinetic analysis was performed using the NONMEM computer program. Results from data analysis showed non-linear pharmacokinetics of ABT-773, noted by the increases in half-life (3.1 to 27.2 h) and AUC/dose (23.7 to 149 mg h−1 L−1 mg−1), with doses from 25 to 200 mg kg−1. A non-linear one-compartment model with parallel capacity-limited and linear first-order elimination best described the pharmacokinetics of ABT-773 in the mouse. The total volume of distribution was 0.316 L. The clearance for the linear first-order elimination was 0.0027 L h−1. The Vm and Km were 0.0385 L h−1 and 0.141 mg L−1, respectively, for the capacity-limited elimination.
Potent apoptotic effects of saponins from Liliaceae plants in L1210 cells
Authors: Candra E , Matsunaga K , Fujiwara H , Mimaki Y , Kuroda M , Sashida Y , Ohizumi Y
Published: October 2002

We isolated eight saponins, a hexacyclic lanosterol tetraglycoside (1), a 27-norlanosterol tetraglycoside (2) and six spirostanol oligoglycosides (3–8), from the plants of the family Liliaceae. In murine leukaemic L1210 cells, saponins 5 and 7 at a concentration of 1 μM showed potent cytotoxic activity and the activities were in the following decreasing order: 5, 7, 1, 3, 2, 8,4, 6. At a concentration of 10 μM, not only 5 and 7 but also 3 and 8 markedly caused cell death. The flow cytometric analysis indicated that 7 and 8 caused a concentration- and time- dependent apoptosis of L1210 cells (EC50 value = ∼5 μM). The morphological observation using a light microscope revealed that both 7 and 8 induced shrinkage in cell soma and chromatin condensation, suggesting apoptotic cell death. Moreover, in agarose gel electrophoretic analysis, a typical apoptotic DNA ladder pattern was observed after treatment with both 7 and 8. These results suggest that 7 and 8 caused the death of L1210 cells through the apoptotic process. These compounds may become powerful pharmacological tools for studying the molecular mechanism of apoptosis.
Effects of adenosine agonists on consumptive behaviour and body temperature
Authors: Coupar Ian M , Tran Binh L T
Published: October 2002

This study was designed to determine the effects of the A1-receptor selective agonist N6- cyclopentyladenosine (CPA), and the A2-selective agonist, 2-p-(2-carboxyethyl)-phenethyl-amino-5′-N-ethylcarboxamidoadenosine-hydrochloride (CGS-21680) on consumptive behaviour and body temperature in rats in relation to the non-selective A1/A2 adenosine agonist, N-ethylcarboxamidoadenosine (NECA), and to morphine. It was shown that two subcutaneous injections of 0.1 and 0.3 mg kg−1 CPA caused a similar decrease in food consumption to NECA (2 × 0.03 mg kg−1) and morphine (2 × 10 mg kg−1). However, two doses of 0.03 mg kg−1 CPA and 0.1 and 0.3 mg kg−1 CGS-21680 enhanced feeding. These effects were not directly correlated to faecal output at all doses of the selective agonists, as NECA and morphine induced constipation. The doses of CPA and 0.1 and 0.3 mg kg−1 of CGS-21680 enhanced water consumption, as did NECA, but not morphine. The stimulation of drinking by CPA was not absolutely associated with diuresis. Instead, urine output was reduced by 0.03 and 0.1 mg kg−1 and increased by 0.3 mg kg−1. CGS-21680 at 0.1 and 0.3 mg kg−1 and NECA also induced diuresis, which was opposite to the effect of morphine. CPA and CGS-21680 both caused significant dose-dependent decreases in body temperature after the two-injection treatment, but their effects were significantly less after 36 h when four doses had been administered. The study indicates that highly selective A1 and A2A adenosine agonists might have the ability to interfere with consumptive behaviour, induce constipation, affect renal function and to lower body temperature.
Aminated gelatin as a nasal absorption enhancer for peptide drugs: evaluation of absorption enhancing effect and nasal mucosa perturbation in rats
Authors: Wang Jian , Sakai Shigeko , Deguchi Yoshiharu , Bi Dianzhou , Tabata Yasuhiko , Morimoto Kazuhiro
Published: October 2002

This study was carried out to evaluate the potential of aminated gelatin as a nasal absorption enhancer for peptide drugs. The absorption-enhancing effect was investigated in rats using insulin and fluorescein isothiocyanate-dextran with a molecular weight of 4.4 kDa (FD-4) as model drugs. The absorption of insulin was estimated by measuring the changes in plasma glucose levels following intranasal administration, and that of FD-4 was determined by measuring its plasma concentration after dosing. The hypoglycaemic effect after intranasal administration of insulin with aminated gelatin significantly increased compared with that after intranasal administration of insulin in phosphate buffered saline, indicating that aminated gelatin effectively enhanced the nasal absorption of insulin. In contrast, neither kind of native gelatin (isoelectric point = 5.0 and 9.0) showed any absorption-enhancing effect. The pH of the formulations and the concentration of aminated gelatin were found to affect the hypoglycaemic effect. In addition, aminated gelatin at a concentration of 0.2 % significantly enhanced the absorption and the efflux of FD-4 through the rat nasal mucosa. The possible perturbation of aminated gelatin to nasal mucosa was evaluated by measuring the leaching of lactate dehydrogenase (LDH) using an in-situ perfusion rat model. Aminated gelatin presented a concentration-dependent (0.1-0.4 %) but relatively small effect on the LDH leaching from the rat nasal epithelial membrane. These results suggest that positively charged aminated gelatin could be a new absorption enhancer for nasal delivery of peptide drugs.
Recent trends in stabilizing protein structure upon encapsulation and release from bioerodible polymers
Authors: Pérez Caroline , Castellanos Ingrid J , Costantino Henry R , Al-Azzam Wasfi , Griebenow Kai
Published: October 2002

Sustained release of pharmaceutical proteins from biocompatible polymers offers new opportunities in the treatment and prevention of disease. The manufacturing of such sustained-release dosage forms, and also the release from them, can impose substantial stresses on the chemical integrity and native, three-dimensional structure of proteins. Recently, novel strategies have been developed towards elucidation and amelioration of these stresses. Non-invasive technologies have been implemented to investigate the complex destabilization pathways that can occur. Such insights allow for rational approaches to protect proteins upon encapsulation and release from bioerodible systems. Stabilization of proteins when utilizing the most commonly employed procedure, the water-in-oil-in-water (w/o/w) double emulsion technique, requires approaches that are based mainly on either increasing the thermodynamic stability of the protein or preventing contact of the protein with the destabilizing agent (e.g. the water/oil interface) by use of various additives. However, protein stability is still often problematic when using the w/o/w technique, and thus alternative methods have become increasingly popular. These methods, such as the solid-in-oil-in-oil (s/o/o) and solid-in-oil-in-water (s/o/w) techniques, are based on the suspension of dry protein powders in an anhydrous organic solvent. It has become apparent that protein structure in the organic phase is stabilized because the protein is “rigidified” and therefore unfolding and large protein structural perturbations are kinetically prohibited. This review focuses on strategies leading to the stabilization of protein structure when employing these different encapsulation procedures.
The long-lasting anti-anginal effects of CP-0605 in a rat model of arginine vasopressin-induced myocardial ischaemia
Authors: Adachi Yuichiro , Suzuki Yoshiyuki , Hatanaka Takahiro , Fukazawa Masanori , Tamura Kazuhiko
Published: October 2002

The anti-anginal effect of CP-060S, a new cardioprotective agent that prevents myocardial Na+-, Ca2+-overload and has Ca2+-channel blocking activity, was evaluated in a rat model of arginine8-vasopressin (AVP)-induced cardiac ischaemia. Infusion of AVP (0.2 IU kg−1) depressed the electrocardiogram (ECG) ST segment, an index of myocardial ischaemia. Vehicle, CP-060S and diltiazem were given orally 1, 2, 4, 8, 12 and 24 h before the administration of AVP. CP-060S, at 3 mg kg−1 and 10 mg kg−1, suppressed AVP-induced ST-segment depression for 2 h and 12 h, respectively. In contrast, diltiazem, at 10 and 30 mg kg−1, suppressed AVP-induced ST-segment depression for only 1 h. The persistent suppression of the AVP-induced ST-segment depression by CP-060S correlated with the time course of changes in its plasma concentration. The minimum effective concentration of CP-060S was estimated to be 30 ng mL−1 (≅ 50 nwi), consistent with its vasorelaxant potency in rat isolated aortic strips (concentration producing 50% relaxation of KCl contraction, IC50 = 32.6 ± 8.3 nM). Intravenously administered CP-060S, at 300 μg kg−1 and diltiazem at 500 μg kg−1 showed similar haemodynamic changes, whereas CP-060S, at 300 μg kg−1, significantly suppressed AVP-induced ST-segment depression and diltiazem, at 500 μg kg−1, had no effect on AVP-induced ST-segment depression. In summary, orally administered CP-060S exerted a long-lasting anti-anginal effect proportionate to the time course of changes in its plasma concentration in a rat model of AVP-induced ischaemia.
A validated high performance liquid chromatographic method for the analysis of Goldenseal
Authors: Li Wenkui , Fitzloff John F
Published: October 2002

Goldenseal (Hydrastis canadensis L.) has emerged as one of the top ten herbal supplements on the worldwide market. A rapid, simple and validated high performance liquid chromatographic method, with photodiode array detection, has been developed for the analysis of commercial Goldenseal products. Samples were treated by sonication with acidified methanol/water. The method was validated for LOD, LOQ, linearity, reproducibility and recovery with good results.
Natural products as targeted modulators of the nuclear factor-κB pathway
Authors: Bremner Paul , Heinrich Michael
Published: October 2002

The use of plant extracts to alleviate inflammatory diseases is centuries old and continues to this day. This review assesses the current understanding of the use of such plants and natural products isolated from them in terms of their action against the ubiquitous transcription factor, nuclear factor kappa B (NF-κB). As an activator of many pro-inflammatory cytokines and inflammatory processes the modulation of the NF-κB transduction pathway is a principal target to alleviate the symptoms of such diseases as arthritis, inflammatory bowel disease and asthma. Two pathways of NF-κB activation will first be summarised, leading to the Ikk (IkB kinase) complex, that subsequently initiates phosphorylation of the NF-κB inhibitory protein (IkB). Natural products and some extracts are reviewed and assessed for their activity and potency as NF-κB inhibitors. A large number of compounds are currently known as NF-κB modulators and include the isoprenoids, most notably kaurene diterpenoids and members of the sesquiterpene lactones class, several phenolics including curcumin and flavonoids such as silybin. Additional data on cellular toxicity are also highlighted as an exclusion principle for pursuing such compounds in clinical development. In addition, where enough data exists some conclusions on structure-activity relationship are provided.
Efficacy of lactosaminated and intact N-succinyl-chitosan-mitomycin C conjugates against M5076 liver metastatic cancer
Authors: Kato Yoshinori , Onishi Hiraku , Machida Yoshiharu
Published: October 2002

In this study, lactosaminated N-succinyl-chitosan (Lac-Suc) was investigated for its liver targeting ability in the early metastatic stage of liver cancer, and subsequently Lac-Suc-mitomycin C conjugate (Lac-Suc-MMC) and highly-succinylated N-succinyl-chitosan (Suc(II))-MMC conjugate (Suc(II)-MMC) were examined for efficacy against the liver metastasis. Mice into which M5076 cells were inoculated intravenously were used as liver metastatic models. Fluorescently labelled Lac-Suc (Lac-Suc-FTC) was intravenously administered at a daily dose of 0.2 mg/mouse for 4 days or at a single dose of 0.8 mg/mouse at 3 days post-inoculation. At a dose of 0.2 mg/mouse for 4 days, liver accumulation of Lac-Suc-FTC was increased after all except the fourth injection, indicating that the capacity of accumulation might be limited to around 110μg per mouse with repeated daily administration at 0.2 mg/mouse. As to the efficacy of intravenous administration at 7 days post-inoculation, Lac-Suc-MMC was less effective at a dose of 1 mg kg−1 for 4 days than a single dose of 4 mg kg−1. This result was not in accordance with that expected from the biodistribution study. On the other hand, with intravenous administration at 3 days post-inoculation, Suc(II)-MMC was more effective on repeated administration, and it showed higher efficacy than Lac-Suc-MMC at both 1 mg kg−1 for 4 days and 4 mg kg−1 as a single dose. Further, with intravenous administration at 3 days post-inoculation, Suc(II)-MMC exhibited a much higher survival effect at a dose of 4 mg kg−1 for 4 days.
Preventive effects of a traditional Chinese formulation, Chaihu-jia-Longgu-Muli-tang, on intimal thickening of carotid artery injured by balloon endothelial denudation in rats
Authors: Kim Dong-Wook , Chung Hwa-Jin , Nose Katsuya , Maruyama Ikuro , Tani Tadato
Published: October 2002

We report here that the traditional Chinese formulation, Chaihu-jia-Longgu-Muli-tang (CLM), significantly inhibited the increase in intimal thickening in rat carotid artery injured by balloon endothelial denudation, which mimics many aspects of restenosis after percutaneous coronary intervention (PCI) in humans. CLM, Saiko-ka-Ryukotsu-Borei-to in Japanese, is commonly prescribed for symptoms accompanying hypertension and atherosclerosis in Japanese kampo medical care. CLM administered orally 1 week before and 1, 4 and 8 weeks after balloon injury inhibited the increase in intimal area, intimal/medial ratio and stenosis ratio. To our knowledge, this is the first report demonstrating inhibitory effects of a traditional Chinese formulation on intimal thickening of carotid artery after balloon injury. It is worth noting that CLM maintained its inhibitory effect up to 8 weeks after balloon injury. The reduction in intimal thickening by CLM could have resulted from inhibition of intimal smooth muscle cell proliferation, which was assessed by immuno-histochemical analysis using monoclonal antibody against proliferating cell nuclear antigen. Therefore, CLM may be a favourable candidate for prevention of restenosis after PCI. Moreover CLM may have a therapeutic value in the prevention of atherosclerosis, because restenosis after PCI is considered to be an accelerated atherosclerosis.
Non-steroidal anti-inflammatory drugs inhibit epinephrine- and cAMP-mediated lipolysis in isolated rat adipocytes
Authors: de Piña M Zentella , Vázquez-Meza H , Piña-Zentella G , Pimentel L , Piña E
Published: October 2002

Acute ethanol intoxication increased triacylglycerides (TAG) and thiobarbituric acid reactive substances (TBARS) in liver and promoted the liberation of epinephrine. Four non-steroidal anti-inflammatory drugs (NSAIDs) - aspirin, naproxen, nimesulide and piroxicam - prevented this increase in TAG and TBARS. Because fatty acids provided by adipose tissue contribute substantially to elevated hepatic TAG in ethanol-intoxicated rats, it was thought that the NSAIDs might reduce epinephrine-stimulated lipolysis in these rats. Isolated rat adipocytes were activated with epinephrine in the presence or absence of the NSAIDs. The NSAIDs inhibited epinephrine-stimulated lipolysis. These drugs did not modify the binding of dihydroalprenolol (β-adrenergic agonist) to their receptors in isolated guinea-pig liver membranes. The NSAIDs, at concentrations 3000-fold lower than that of cAMP, inhibited stimulated lipolysis by this messenger. In conclusion, aspirin, naproxen, nimesulide and piroxicam reduce the release of fatty acids from adipose tissue to the liver by inhibiting the epinephrine-stimulated lipolysis, and this, in part, explains the protective action of these NSAIDs against hepatic signs of acute ethanol intoxication.
Development of a lyophilised RH1 formulation: a novel DT diaphorase activated alkylating agent
Authors: Elliott M A , Ford S J , Walker A A , Hargreaves R H J , Halbert G W
Published: October 2002

RH1 is a novel aziridinylbenzoquinone alkylating agent, which is activated in tumour cells by DT diaphorase. In common with previous aziridinylbenzoquinones, RH1 exhibits limited aqueous stability and solubility. The aim of this study was to examine the pharmaceutical properties of RH1 with a view to preparing a suitable formulation for clinical trial. Stability in a neutral phosphate-buffered solution was poor with a degradation half-life of 50 h at 55°C, indicating that lyophilisation was preferable. The reaction kinetics indicated a similarity with previous studies for base-catalysed degradation of aziridinylbenzoquinones. Intrinsic aqueous solubility at 0.5 mg mL−1 may be increased in solvent systems or by the use of polymers such as polyvinylpyrrolidone (PVP) or complexing agents like hydroxypropyl-β-cyclodextrin (HPBCD). In the latter case this increased solubility by an order of magnitude to around 5 mg mL−1. Four potential formulations based on lyophilisation of RH1 (1 mg mL−1) from buffered solution (pH 7, 0.01 M NaH2PO4) containing either 50 mg mL−1 mannitol, 40 mg mL−1 dextran, 20 mg mL−1 PVP or 50 mg mL−1 HPBCD were prepared and examined for stability characteristics. All formulations exhibited a temperature-dependent degradation. The mannitol and dextran formulations had limited stability and degraded rapidly at all temperatures. The PVP and HPBCD formulations degraded at elevated temperatures but remained stable for up to twelve months at 4°C. Examination of the degradation kinetics in the latter systems demonstrated similarity to the solution degradation mechanism, while in the former alternative degradation pathways appeared to be occurring. The chemical stability of RH1 in lyophilised formulations is dependent upon the excipient employed and storage temperature. Either the PVP or HPBCD formulation would be suitable clinical trial formulations of RH1. The results indicate that the choice of lyophilisation excipient for aziridinylbenzoquinones cannot be based on previous literature studies of related agents.
Pharmacological properties and SAR of new 1,4-disubstituted piperazine derivatives with hypnotic-sedative activity
Authors: Chilmonczyk Zdzislaw , Mazgajska Maria , Iskra-Jopa Joanna , Chojnacka-Wójcik Ewa , Tatarczyńka Ewa , Klodzińska Aleksandra , Nowak Jerzy Z
Published: October 2002

Preparation, pharmacological properties and structure-activity relationships of new pyrimidylpiperazine derivatives, exhibiting sedative and hypnotic activity in mice, are reported. The hypnotic activity of the compounds was comparable with that of zopiclone (the known hypnotic-sedative agent), their interaction with ethanol, however, being much lower. The obtained results suggested that zopiclone and pyrimidylpiperazines 2, 4 and 5 exerted their pharmacological activity through a different mechanism — zopiclone through the interaction with benzodiazepine receptors and compounds 2, 4 and 5 through an unidentified molecular target. The pharmacological properties of compound 3 could be the result of a mixed mechanism of action, combining the properties of zopiclone and those of compounds 2, 4 and 5. A common feature of zopiclone and compounds 2 and 3 was that, after their systemic administration, independently of mechanism of action, together with the hypnotic effect a reduction of the 5-HT turnover in the mouse brain was observed. Minimum structural requirements for the hypnotic activity were formulated. Structural considerations have shown that removing the α-carbonyl group did not influence the drug's ability to inhibit the locomotor activity. However, it did influence its ability to disturb motor coordination or abolish the righting reflex within non-lethal doses.
Effects of dofetilide on cardiovascular tissues from normo- and hypertensive rats
Authors: Doggrell Sheila A , Nand Vinita
Published: October 2002

The aim was to test whether dofetilide has some potential for use in the treatment of heart failure. Dofetilide at ≤3 times 10−5 M had no effect on the quiescent Wistar Kyoto (WKY) rat aorta, mesenteric and intralobar arteries, or the spontaneous contractions of the WKY rat portal vein. Dofetilide at 10−6 to 3 times 10−5 M relaxed the KCl-contracted aorta. Dofetilide at 10−9-10−7 M augmented the force of contraction of left ventricle strips from 12- and 18-month-old WKY rats at 2 Hz. Spontaneously hypertensive rats (SHRs) at 12 and 17–21 months of age are models of cardiac hypertrophy and failure, respectively. The augmentation of force at 2 Hz with dofetilide was similar on 12-and 18-month-old WKY rats and 12-month-old SHRs but reduced on the 18-month-old SHR left ventricle. At a higher more physiological frequency, 4 Hz, the threshold concentration of dofetilide required to augment the force responses of 21-month-old SHR left ventricles was markedly increased and the maximum augmenting effect was decreased. Dofetilide at 10−7-10−5 M reduced the rate of the 17-month-old WKY rat right atrium, and had a similar effect on age-matched SHR right atrium. In summary, dofetilide is a positive inotrope and negative chronotrope in the rat. However, as the positive inotropic effect is not observed with clinically relevant concentrations at a physiological rate in heart failure, dofetilide is unlikely to be useful as a positive inotrope in the treatment of heart failure.
Estimation of cyclodextrin affinity to steroids
Authors: Khomutov S M , Sidorov I A , Dovbnya D V , Donova M V
Published: October 2002

A nonlinear spectrometric method for determination of the stability constant (KS) for cyclodextrin complex with steroid was developed. The method is based on calculation of the parameters of competitive cyclodextrin complexation by simultaneous fitting of two types of curves. Those of the first type are the dependencies of absorbance of methyl orange solution on the cyclodextrin concentration, the second type being the absorption curves of displacement of the dye, by steroid, from the cyclodextrin complex. With the method proposed, KS values were calculated with standard deviation less than 10%. This method is validated by determination of KS values using the phase-solubility technique. For neutral steroid molecules, the effect of pH on KS was found to be insignificant. KS values for the cyclodextrin-dye complex were determined for randomly methylated β-cyclodextrin, 2-hydroxypropyl-β-cyclodextrin, carboxymethyl-β-cyclodextrin and sulfobutylether-β-cyclodextrin. More hydrophobic steroids were characterised by higher KS values. Anionic β-cyclodextrins showed high affinity for the steroids studied. Simple equipment and sufficient computing allowed recommendation of the method for express estimation of cyclodextrin's affinity for hydrophobic substrates.
Disordered drug delivery: destiny, dynamics and the Deborah number
Authors: Hancock Bruno C
Published: October 2002

“Disordered drug delivery” is an innovative approach to improving the performance of new chemical entities delivered to the human body. In this technique, the molecules of the drug and/or its delivery system are kinetically trapped in a high energy non-crystalline state. The resulting disordered or “amorphous” material offers potential increases in solubility and biological activity of many thousand fold compared with more conventional crystalline forms of the drug. Despite having a molecular level structure akin to that of liquids, amorphous materials have macroscopic properties that are typical of solids and thus they may be presented to the patient in the form of a convenient solid dosage form. Significant advances in the fundamental understanding of amorphous pharmaceutical materials in the past ten years have permitted major steps forward in the rational design of disordered drug delivery systems. Recognition of significant levels of molecular mobility in the glassy regime and an in-depth appreciation of molecular relaxation times and their distributions have enabled rapid progress to be made in this field. Needs for the future include analytical techniques that can elucidate the complex, dynamic and heterogeneous structure of amorphous materials and reliable models to predict the physical stability and in-vivo performance of disordered drug delivery systems. There are also significant opportunities for the production of disordered drug delivery systems with tailor-made properties through the careful engineering of custom amorphous alloys.
Reversal of cannabinoids (Δ9-THC) by the benzoflavone moiety from methanol extract of Passiflora incarnata Linneaus in mice: a possible therapy for cannabinoid addiction
Authors: Dhawan Kamaldeep , Kumar Suresh , Sharma Anupam
Published: October 2002

The newly reported benzoflavone moiety from the plant Passiflora incarnata Linneaus has been evaluated in light of traditional reports on the use of P. incarnata in breaking down cannabis addiction. In the modern or allopathic system of therapeutics, there has been no suitable remedy to combat the severe withdrawal effects of various cannabis products, including marihuana, marijuana, bhang, hashish, ganja, etc., the world-wide consumption of which has attained alarming proportions especially among the younger generation. Mice were given a 10-mg-kg−1 twice-daily dose of δ9-tetrahydrocannabinol (δ9-THC) by mouth for six days to make them dependent upon cannabinoids. Concurrently, other groups of mice were administered δ9-THC along with a 10- or 20-mg-kg−1 twice-daily dose of the benzoflavone moiety from P. incarnata orally for 6 days. Upon measuring locomotor activity during the treatment regimen, it was noticed that the mice receiving the P. incarnata extract and δ9-THC together developed significantly less tolerance and dependence, relative to the mice receiving δ9-THC alone. Upon administration of SR-141716A, a selective cannabinoid-receptor antagonist (10 mg kg−1, p.o.) to all the groups of mice on the 7th day, an artificial withdrawal was produced due to an abrupt decline of δ9-THC levels in mouse brain. However, the typical withdrawal effects like paw tremors and head shakes were significantly less in the mice given δ9-THC + P. incarnata benzoflavone moiety for 6 days. Upon administration of 20 mg kg−1 of the P. incarnata benzoflavone moiety to mice showing severe symptoms of withdrawal due to administration of SR-141716A, there was a marked attenuation of withdrawal effects, thereby suggesting the usefulness of the benzoflavone moiety in δ9-THC withdrawal. Thus, the benzoflavone moiety of P. incarnata, when administered concurrently with δ9-THC, prevented the development of tolerance and dependence of cannabinoids in mice. Even an acute administration of the benzoflavone moiety (20 mg kg−1, p.o.) significantly blocked the expression of withdrawal effects in δ9-THC-dependent mice.
In-vitro release of bupivacaine from injectable lipid formulations investigated by a single drop technique — relation to duration of action in-vivo
Authors: Söderberg Lars , Dyhre Henrik , Roth Bodil , Björkman Sven
Published: October 2002

The aim of this study was to develop an in-vitro release method suitable for injectable slow-release lipid formulations of local anaesthetics (or other drugs). We also aimed that the results of the in-vitro measurements should have a clear relationship to duration of action in-vivo. Six formulations of bupivacaine base in medium-chain triglyceride-glyceryl dilaurate mixtures were developed. A new apparatus was constructed for determination of their in-vitro release profiles. A bulbous glass tube was fixed inside a standard glass bottle, which was then filled with release medium. A stirring magnet was enclosed in the perforated polypropylene cylinder holding the glass tube. The stirring created a continuous, rotating downward flow of medium inside the tube, which kept the lipid phase, introduced by means of a syringe, suspended as a single, free drop. Release profiles were obtained by sampling of the release medium for up to 72 h and analysis by gas-liquid chromatography. The duration of action in-vivo of the respective formulations was tested by the hot-plate method in rats. The release profiles of bupivacaine in-vitro were mono-exponential for four formulations and bi-exponential for the other two. There was a positive correlation between the proportion of glyceryl dilaurate in the formulation and the slow half-life of release of bupivacaine. All formulations showed prolonged duration of action in-vivo, median values within the range 4.5–12 h, as compared with a 2-h effect of bupivacaine hydrochloride solution. A comparison of in-vitro release curves and durations of action in-vivo suggested that to maintain nerve blockade in-vivo the formulations must release bupivacaine at a rate of approximately 350 μg h−1 under the in-vitro conditions. To conclude, we designed and tested a novel apparatus for measuring release of a local anaesthetic (or other drug) from a fluid or semi-solid formulation in-vitro. Release rates obtained in-vitro by means of this technique may be used to guide the development of formulations with suitable durations of action in-vivo. The apparatus is, however, as yet a prototype. Rigorous evaluation of performance should be carried out on devices built to specific standards according to their intended application.
Interaction of double-chained cationic surfactants, dimethyldialkylammoniums, with erythrocyte membranes: stabilization of the cationic vesicles by phosphatidylcholines with unsaturated fatty acyl chains
Authors: Kitagawa Shuji , Hiyama Fuyuko , Kato Miwa , Watanabe Reiho
Published: October 2002

We studied the interaction of double-chained cationic surfactants, dimethyldialkylammoniums, (CH3)2N+(CnH2n+1)2, with the lipid bilayer of guinea-pig erythrocytes by observing the haemolysis, aggregation and shape change in the erythrocytes. In the presence of sonicated dispersions of the five dimethyldialkylammoniumstested (n = 10,12,14,16 and 18), haemolysiswas induced dose dependently, and at 0.1 mM or higher concentrations, haemolysis was induced more rapidly by dimethyldialkylammoniums with shorter alkyl chains. The cationic surfactants with longer alkyl chains, such as dimethyldipalmitylammonium, induced aggregation of the erythrocytes before haemolysis fully progressed. The vesicles of these long-chain dimethyldialkylammoniums in the presence of phosphatidylcholines with unsaturated fatty acyl chains markedly reduced the haemolysis rates. Furthermore, in the presence of phosphatidylcholines with unsaturated acyl chains the formation of tightly aggregated structures of several erythrocytes was observed. These findings, and analysis by spin label 5-doxylstearic acid, indicate that phosphatidylcholines enriched with unsaturated acyl chains stabilize the cationic vesicles of long-chain dimethyldialkylammoniums and the interaction with the lipid bilayer of erythrocyte membranes as cationic vesicles became prominent.
Pharmacokinetic-pharmacodynamic modelling of insulin: comparison of indirect pharmacodynamic response with effect-compartment link models
Authors: Lin Senshang , Chien Yie W
Published: October 2002

The pharmacokinetic and pharmacodynamic modelling of insulin has been reported using a combined pharmacokinetic/pharmacodynamic (PK/PD) model, in which a hypothetical effect compartment is linked to a pharmacokinetic compartment. Review of the literature, however, indicated that the recently developed PK/PD models have consisted of an indirect pharmacodynamic response component, but none of them has been applied to the modelling of insulin. To study the relative relevance of the indirect pharmacodynamic response model and the effect-compartment link model in modelling the pharmacokinetics and pharmacodynamics of insulin, regular human insulin was administered intravenously at a dose of 0.1 IU kg−1 to healthy Yucatan minipigs (after an overnight fasting). The plasma concentrations of insulin were measured by radioimmunoassay at predetermined time intervals, while blood glucose levels were monitored continuously using a glucose monitor. Analysis of the plasma insulin and the blood glucose profiles was performed by fitting with various PK/PD models and the results indicated that all of the 12 sets of plasma insulin data (after normalizing by the basal levels) have been adequately fitted to the two-compartment open pharmacokinetic model (a mean±s.e. correlation coefficient of 0.996±0.001 was obtained). The mean±s.e. correlation coefficient, the weighted residuals sum of squares (WRSS), and the Akaike's information criterion (AIC) were found, respectively, to be 0.935 ± 0.008, 624±67, and 522 ± 9 for the inhibitory indirect pharmacodynamic response model and 0.941±0.010, 547 ± 63 and 513 ± 9 for the stimulatory indirect pharmacodynamic response model, as compared with 0.725 ± 0.041, 2309 ± 276 and 628 ± 10 for the effect-compartment link model. Based on these results, one may conclude that the indirect pharmacodynamic response model is a more appropriate approach for modelling the PK/PD of insulin than the effect-compartment link model.
Electrically enhanced transdermal delivery of a macromolecule
Authors: Badkar Advait V , Banga Ajay K
Published: October 2002

The purpose of this study was to establish the delivery parameters for the enhanced transdermal delivery of dextran sulfate (MW 5000 Da). Full-thickness pig skin or epidermis separated from human cadaver skin was used. Silver-silver chloride electrodes were used to deliver the current (0.5 mA cm−2). For electroporation experiments, one or more pulses were given using an exponential decay pulse generator. The correct polarity for iontophoresis and pulsing was first established as cathode in the donor. The amount of drug delivered increased with increasing donor concentration up to a point, but not any further. The amount delivered also increased with pulse voltage, the delivery being twice as much as with iontophoresis alone (144.5 ± 10.35 μg cm−2), when 6 pulses of 500 V were applied at time zero before iontophoresis (276 ± 45.2 μg cm−2). It was observed that the amount delivered was a function of increasing pulse length when the apparent charge delivered was kept constant. Transport through pig skin (107.4 ± 24.4 μg cm−2) was found to be comparable with that through human epidermis (84.9 ± 18.4 μ g cm−2). In conclusion, we have demonstrated the transdermal delivery of a 5000 Da molecular weight dextran sulfate using iontophoresis. It was also seen that iontophoretic delivery could be enhanced by simultaneous electroporation.
Non-specific binding of the experimental anti-cancer drug 5,6-dimethylxanthenone-4-acetic acid (DMXAA) in liver microsomes from various species
Authors: Zhou Shufeng , Kestell Philip , Paxton James W
Published: October 2002

Total (added) drug concentrations other than unbound concentrations have been used to estimate the in-vitro enzyme kinetic parameters for 5,6-dimethylxanthenone-4-acetic acid (DMXAA), an experimental anti-cancer drug. This study aimed to investigate the non-specific binding of DMXAA to liver microsomes from various species and to microsomes from human lymphoblastoid cells expressing drug-metabolising enzymes, and to examine the effect of the binding on the estimation of enzyme kinetic parameters for DMXAA in-vitro. The separation of unbound DMXAA was conducted by ultrafiltration and DMXAA concentrations were determined by validated HPLC. The results indicated that DMXAA was bound to liver microsomes and lymphoblastoid cell microsomes to a small extent (free fraction in microsomes, fu(mic) mostly > 0.85). Correction for the unbound DMXAA concentration resulted in slightly lower apparent Michaelis-Menten constant (Km) values, but with the maximal velocity of reaction (Vmax) unchanged, leading to slightly higher unbound Vmax/Km values. These results indicate that the non-specific binding of DMXAA to microsomes is insignificant and has little impact on the enzyme kinetic estimation in-vitro.
Areas of components of a Voronoi polygon in a homogeneous Poisson process in the plane
Authors: Hayen A. , Quine M. P.
Published: October 2002

We study the contribution made by three or four points to certain areas associated with a typical polygon in a Voronoi tessellation of a planar Poisson process. We obtain some new results about moments and distributions and give simple proofs of some known results. We also use Robbins' formula to obtain the first three moments of the area of a typical polygon and hence the variance of the area of the polygon covering the origin.
The loss of tension in an infinite membrane with holes distributed according to a Poisson law
Authors: Menshikov M. V. , Rybnikov K. A. , Volkov S. E.
Published: October 2002

What is the effect of punching holes at random in an infinite tensed membrane? When will the membrane still support tension? This problem was introduced by Connelly in connection with applications of rigidity theory to natural sciences. The answer clearly depends on the shapes and the distribution of the holes. We briefly outline a mathematical theory of tension based on graph rigidity theory and introduce a probabilistic model for this problem. We show that if the centers of the holes are distributed in ℝ2 according to a Poisson law with density λ > 0, and the shapes are i.i.d. and independent of the locations of their centers, the tension is lost on all of ℝ2 for any λ. After introducing a certain step-by-step dynamic for the loss of tension, we establish the existence of a nonrandom N = N(λ) such that N steps are almost surely enough for the loss of tension. Also, we prove that N(λ) > 2 almost surely for sufficiently small λ. The processes described in the paper are related to bootstrap and rigidity percolation.
On the infinite cluster of Bernoulli bond percolation in Scherk's graph
Authors: Chen Dayue
Published: October 2002

Scherk's graph is a subgraph of the three-dimensional lattice. It was shown by Markvorsen, McGuinness and Thomassen (1992) that Scherk's graph is transient. Consider the Bernoulli bond percolation in Scherk's graph. We prove that the infinite cluster is transient forp> ½ and is recurrent forp< ½. This implies the well-known result of Grimmett, Kesten and Zhang (1993) on the transience of the infinite cluster of the Bernoulli bond percolation in the three-dimensional lattice forp> ½. On the other hand, Scherk's graph exhibits a new dichotomy in the supercritical region.
An exponential change of measure for the Feller diffusion and some implications for superprocesses
Authors: Adler Robert J. , Iyer Srikanth K.
Published: October 2002

Let Xt be a Feller (branching) diffusion with drift αx. We consider new processes, the probability measures of which are obtained from that of X via changes of measure involving suitably normalized exponential functions of with λ > 0. The new processes can be thought of as ‘self-reinforcing’ versions of the old.

Depending on the values of α, T and λ, the process under the new measure is shown to exhibit explosion in finite time. We also obtain a number of other results related to the new processes.

Since the Feller diffusion is also the total mass process of a superprocess, we relate the finite-time explosion property to the behaviour of superprocesses with local self-interaction, and raise some interesting questions for these.
NWU property of a class of random sums
Authors: Cai Jun , Kalashnikov Vladimir
Published: October 2002

In this note, we derive an inequality for the renewal process. Then, using this inequality, together with an identity in terms of the renewal process for the tails of random sums, we prove that a class of random sums is always new worse than used (NWU). Thus, the well-known NWU property of geometric sums is extended to the class of random sums. This class is illustrated by some examples, including geometric sums, mixed geometric sums, certain mixed Poisson distributions and certain negative binomial sums.