bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gamma failure‐time mixture models: yet another way to establish efficacy
Authors: Koti Kallappa M. 
Published: June 2003

AbstractUsing a Yamaguchi‐type generalized gamma failure‐time mixture model, we analyse the data from a study of autologous and allogeneic bone marrow transplantation in the treatment of high‐risk refractory acute lymphoblastic leukaemia, focusing on the time to recurrence of disease. We develop maximum likelihood techniques for the joint estimation of the surviving fractions and the survivor functions. This includes an approximation to the derivative of the survivor function with respect to the shape parameter. We obtain the maximum likelihood estimates of the model parameters. We also compute the variance‐covariance matrix of the parameter estimators.The extended family of generalized gamma failure‐time mixture models is flexible enough to include many commonly used failure‐time distributions as special cases. Yet these models are not used in practice because of computational difficulties. We claim that we have overcome this problem. The proposed approximation to the derivative of the survivor function with respect to the shape parameter can be used in any statistical package. We also address the issue of lack of identifiability. We point out that there can be a substantial advantage to using the gamma failure‐time mixture models over nonparametric methods. Copyright © 2003 John Wiley & Sons, Ltd.
Examples of option values in drug development
Authors: Burman Carl‐Fredrik , Senn Stephen 
Published: June 2003

AbstractThe option to stop a project is fundamental in drug development. The majority of drugs do not reach the market. Furthermore, many marketed drugs do not repay their development costs. It is therefore crucial to optimize the value of the option to stop.We formulate two examples of statistical models. One is based on success/failure in a series of trials; the other assumes that the commercial value evolves as a stochastic process as more information becomes available. These models are used to study a number of issues: the number and timing of decision points; value of information; speed of development; and order of trials.The results quantify the value of options. They show that early information that can change key decisions is most valuable. That is, we should nip bad projects in the bud. Modelling is also useful to analyse more complex decisions, for example, weighting the value of decision points against the cost of information or the speed of development. Copyright © 2003 John Wiley & Sons, Ltd.
Inhibition of the progression of type 2 diabetes in the C57BL/6J mouse model by an anti‐diabetes herbal formula
Authors: Winters Wendell D. , Huo Yu Shu , Yao Da‐Lin 
Published: June 2003

AbstractThe effects of a speciﬁcally prepared anti‐diabetic herbal formula (ADHF) on the course of established diet‐induced type 2 diabetes in animal subjects has been studied. In a C57BL/6J mouse model for diet induced type 2 diabetes, intervention for 12 weeks using ADHF as a diet supplement resulted in a signiﬁcant inhibition of diabetes related changes in major organs usually targeted by type 2 diabetes and a signiﬁcant reduction in circulating levels of glucose and insulin. Young male mice were randomly assigned to receive ad libitum exposure to either a standard rodent chow diet or to a high fat, high simple sugar, low ﬁbre diet (diabetes induction diet), respectively for 8 weeks. All mice fed the induction diet developed abnormally high blood glucose levels at 8 weeks. Animals with conﬁrmed diet induced diabetic blood glucose levels were again randomly assigned into one of three groups (10 subjects per group), one group was thereafter fed only the diabetes induction diet and the other two groups were thereafter fed the diabetes induction diet into which ADHF had been mixed at 4% or at 8% ﬁnal concentrations. Normal mice were also randomized into two groups that were fed either a regular diet alone or 8% ADHF mixed in the regular diet. Blood glucose levels markedly increased over the 20 weeks of study in the diabetic mice fed the diabetes induction diet only. In contrast, diabetic mice fed induction diet into which 4% or 8% ADHF had been incorporated showed signiﬁcantly decreased blood glucose and insulin levels over the time of the study. Additional parameters signiﬁcantly reduced in diabetic mice fed ADHF included insulin resistance and histopathological changes in the pancreas and liver. This is the ﬁrst report to our knowledge to show in vivo evidence for signiﬁcantly decreased circulating glucose and insulin levels and a signiﬁcant reduction of progressive damage to major target organs by the addition of an herbal diet supplement to a diabetes induction diet proven to be capable of causing and maintaining type 2 diabetes. Copyright © 2003 John Wiley & Sons, Ltd.
Antifungal compounds from Zanthoxylum chiloperone var. angustifolium
Authors: Thouvenel Céline , Gantier Jean‐Charles , Duret Philippe , Fourneau Christophe , Hocquemiller Reynald , Ferreira Maria‐Elena , de Arias Antonieta Rojas , Fournet Alain 
Published: June 2003

AbstractAn alkaloidal extract of the stem barks of Zanthoxylum chiloperone var. angustifolium exhibited antifungal activity against Candida albicans, Aspergillus fumigatus and Trichophyton mentagrophytes var. interdigitale using a TLC bioautographic method. Bioassay‐guided fractionation of this extract resulted in the isolation of two active compounds identiﬁed as canthin‐6‐one and 5‐methoxycanthin‐6‐one. Canthin‐6‐one exhibited a broad spectrum of activities against Aspergillus fumigatus, A. niger, A. terreus, Candida albicans, C. tropicalis, C. glabrata, Cryptococcus neoformans, Geotrichum candidum, Saccharomyces cerevisiae, Trichosporon beigelii, Trichosporon cutaneum and Trichophyton mentagrophytes var. interdigitale with MICs values between 5.3 and 46 µmol/L. 5‐methoxy‐canthin‐6‐one was active against only Trichophyton mentagrophytes var. interdigitale with a MIC value of 12.3 µmol/L. Copyright © 2003 John Wiley & Sons, Ltd.
Antiprotozoal activity of the constituents of Rubus coriifolius
Authors: Alanís Alma Delia , Calzada Fernando , Cedillo‐Rivera Roberto , Meckes Mariana 
Published: June 2003

AbstractExtraction of the aerial parts of Rubus coriifolius, a medicinal plant used by the Maya communities in Southern Mexico to treat bloody diarrhoea, resulted in the isolation of seven known compounds (−)‐epicatechin, (+)‐catechin, hyperin, nigaichigoside F1, β‐sitosterol 3‐O‐β‐d‐glucopyranoside, gallic acid and ellagic acid. All compounds were tested for their antiprotozoal activity against Entamoeba histolytica and Giardia lambia. Epicatechin was the main responsible for the antiprotozoal activity of the extract against both protozoa, its activity was comparable to emetine, but no exceeded that of metronidazole. Copyright © 2003 John Wiley & Sons, Ltd.
Evaluation of efficacy and safety of a herbal medicine used for the treatment of malaria
Authors: Ankrah Nii‐Ayi , Nyarko Alexander K. , Addo Phyllis G. A. , Ofosuhene Mark , Dzokoto Comfort , Marley Ethel , Addae Michael M. , Ekuban Frederick A. 
Published: June 2003

AbstractResistance of Plasmodium falciparum to chloroquine has been reported in several countries. Other anti‐malarial drugs in use are expensive and not readily accessible to most people in malaria endemic countries. This has led to renewed interest in the development of herbal medicines that have the potential to treat malaria with little or no side effects. This study obtained a preliminary information on the safety and effectiveness of a plant decoction (AM‐1), used in treating malaria.The AM‐1 is formulated from Jatropha curcas, Gossypium hirsutum, Physalis angulata and Delonix regia. Patients with suspected malaria attending a herbal clinic were enrolled in the study on voluntary basis. They were hospitalized for treatment, clinical observation, biochemical and haematological monitoring, and parasite clearance while on AM‐1. In addition male and female Sprague Dawley rats were used to evaluate the acute and subchronic toxicity effects of AM‐1.The AM‐1 eliminated malaria parasites (Plasmodium falciparum and Plasmodium malarie) from the peripheral blood of patients with malaria. In addition the AM‐1 did not show any undesired effects in the patients as well as in laboratory rats. The AM‐1, however, showed differential effect on the activities of selected cytochrome P450 isozymes (7‐pentoxyresorufin‐O‐depentylation, 7‐ethoxyresorufin‐O‐deethylation and p‐nitrophenol hydroxylase) in relation to sex of the laboratory rats.These results indicate that AM‐1 could be used to treat malaria. However, it could precipitate interactions with other drugs via their biotransformation and elimination. The obtained data warrant further studies in a large number of malaria subjects with monitoring for possible drug interactions. Copyright © 2003 John Wiley & Sons, Ltd.
Anti‐herpesvirus activity of an extract of Ribes nigrum L.
Authors: Suzutani Tatsuo , Ogasawara Masahiro , Yoshida Itsuro , Azuma Masanobu , Knox Yoko M. 
Published: June 2003

AbstractAn extract of Ribes nigrum L., known as blackcurrant in Europe and Kurokarin® in Japan, has been used as an ingredient in a variety of foods and folk medicine. In this study, the anti‐herpesvirus activity of this extract was examined in vitro. The extract inhibited herpes simplex virus type 1 attachment on the cell membrane completely at a 100‐fold dilution, as well as the plaque formation of herpes simplex virus types 1 and 2, and varicella‐zoster virus by 50% at a 400‐fold dilution or lower concentrations. This latter activity, which inhibits virus replication in cells, was due to the inhibition of protein synthesis in infected cells from the early stage of infection. Kurokarin is a possible candidate as a herbal medicine for herpesvirus infectious diseases. Copyright © 2003 John Wiley & Sons, Ltd.
Protective effects of saffron (Crocus sativus Linn.) on genotoxins‐induced oxidative stress in Swiss albino mice
Authors: Premkumar K. , Abraham Suresh K. , Santhiya S. T. , Ramesh A. 
Published: June 2003

AbstractThe modifying effects of the aqueous extract of saffron (dried stigmas of Crocus sativus Linn.) on cisplatin (CIS), cyclophosphamide (CPH), mitomycin‐C (MMC) and urethane (URE) induced alterations in lipid peroxidation and antioxidant status were investigated in Swiss albino mice. Three doses of saffron (20, 40 and 80 mg/kg body weight) were orally administered to mice for 5 consecutive days prior to administration of genotoxins. A signiﬁcant reduction in the extent of lipid peroxidation with a concomitant increase in the liver enzymatic (SOD, CAT, GST, GPx) and non‐enzymatic antioxidants (reduced glutathione) were observed in saffron pretreated animals compared with the genotoxins alone treated animals. However, the modulatory effects were not always dose dependent. Our data suggest that saffron may exert its chemopreventive effects by modulation of lipid peroxidation, antioxidants and detoxiﬁcation systems. Copyright © 2003 John Wiley & Sons, Ltd.
Antiamoebic activity of benzyl glucosinolate from Lepidium virginicum
Authors: Calzada Fernando , Barbosa Elizabeth , Cedillo‐Rivera Roberto 
Published: June 2003

AbstractIn a continuation of our search for potential antiprotozoal agents from plants, we found that a crude extract from the roots of Lepidium virginicum exhibited antiprotozoal activity against Entamoeba histolytica trophozoites (IC50 of 100.1 µg/mL). Bioassay‐guided fractionation resulted in the isolation of one known glucosinolate responsible for such activity. This compound was identiﬁed as benzyl glucosinolate. It showed in vitro activity against Entamoeba histolytica strain HM1‐IMSS (IC50 of 20.4 µg/mL). The results support the anecdotal reports for the traditional use of L. virginicum roots in the control of diarrhoea and dysentery in the highlands of Chiapas, Mexico. Copyright © 2003 John Wiley & Sons, Ltd.
Comparison of antimalarial activity of the alkaloidal fraction of Hydrangea macrophylla var. Otaksa leaves with the hot‐water extract in ICR mice infected with Plasmodium yoelii 17 XL
Authors: Ishih Akira , Miyase Toshio , Terada Mamoru 
Published: June 2003

AbstractThe antimalarial activity of the fractions isolated from the leaves of Hydrangea macrophylla Seringe var. Otaksa Makino was evaluated against Plasmodium yoelii 17 XL in mice. Four different fractions were prepared in the usual manner to obtain an alkaloid fraction. All mice treated with the fraction containing febrifugine and isofebrifugine mixture at 1 mg/kg twice a day for 5 consecutive days survived during the experiment, and the change of mean parasitemia level showed almost the same pattern as that from mice treated with the hot‐water extract of the same plant leaves. Activity of this fraction, however, was markedly reduced compared with the hot‐water extract. Furthermore, no antimalarial activity was shown in the hotwater extract from H. macrophylla var. Otaksa roots or Dichroa febrifuga Lour. leaves. Copyright © 2003 John Wiley & Sons, Ltd.
Main flavonoids in the root of Scutellaria baicalensis cultivated in Europe and their comparative antiradical properties
Authors: Bochořáková Hana , Paulová Hana , Slanina Jiří , Musil Pavel , Táborská Eva 
Published: June 2003

AbstractThe content of the main flavonoids in the root of Scutellaria baicalensis Georgi cultivated in Central Europe was evaluated using the new simple RP‐HPLC method with gradient of acetonitrile in mobile phase. The main components of the roots were baicalin (8.12% of dry root mass) and wogonin glucuronide (2.52%). The content of flavonoids was comparable with the content in plants cultivated in natural localities. Five main flavonoids were evaluated for their scavenging ability with DPPH radical‐generating system and due to limited solubility only two flavonoids were investigated for their ability to scavenge hydroxyl radical by the aromatic hydroxylation method. The total extract was also tested in both the experimental arrangements. In experiments with DPPH, only baicalin and baicalein displayed a significant scavenging effect, while the production of OH radicals generated by UV photolysis of H2O2 was considerable decreased in the presence of baicalin and wogonin glucuronide. After comparison with results obtained for the total extract, it was concluded, that the scavenging activity of the extract against DPPH is mainly derived from baicalin. On the other hand, baicalin, wogonin glucuronide and probably other flavonoids participate in scavenging OH radical. Copyright © 2003 John Wiley & Sons, Ltd.
Assessment of therapeutic effect of Inula heterolepsis Boiss in alcoholic rats
Authors: Saygi Şahan , Konuklugil Belma , Kutsal Osman , Uzbay İ. Tayfun , Deniz Gönen , Gören Zafer 
Published: June 2003

AbstractAn aqueous extract from the root of Inula heterolepsis Boiss was prepared and then tested for its ability to treat experimentally induced alcoholic hepatic injury in rats. Alcoholic rats were divided into two groups. The ﬁrst group of rats were given 200 mg/kg/day plant extract. Repeated doses of extract preparations were given at 12 h intervals for 10 days. Differences between the recovery of tissue injury, with and without Inula plant extract, were evaluated. The second group of rats were given vehicle. Liver, testis and kidney injuries due to the chronic alcohol consumption were proven biochemically and histopathologically. Rats were killed, serum SGOT, SGPT, alkaline phosphatase, and albumin levels were measured. SGOT, SGPT and alkaline phosphatase levels were signiﬁcantly higher in alcoholic rats due to the tissue damage compared with intact, vehicle and Inula treated groups of rats (p < 0.05). Liver, testis, kidneys, stomach, intestine, heart, lungs and bladder were examined histopathologically. According to our study, the root extract of Inula heterolepsis Boiss has a slight therapeutic effect on alcoholic liver, kidney and testis damage in rats. Comparing the therapeutic effects in these organs, the liver seemed to be affected meaningfully after treatment with the plant extract. Copyright © 2003 John Wiley & Sons, Ltd.
The effect of a strongly basic alkaloidal fraction of Rhazya stricta, a traditional medicinal plant, on cytochrome P450‐mediated metabolism of theophylline in mice
Authors: El‐Kadi A. O. , Tanira M. O. M. , Ali B. H. , Bashir A. K. , Souich P. Du 
Published: June 2003

AbstractThe strongly basic alkaloidal fraction of the traditional medicinal plant Rhazya stricta (RS) was given orally to mice, in a single dose of 10 mg/kg (group 1) or, twice daily for 3 days at the same dose (group 2). A third group (control) received normal saline. Liver homogenates from all animals were used to assess the microsomal activity of cytochrome P450 and its isoforms as well as its catalytic activity (using theophylline as a substrate). RS alkaloidal fraction had no signiﬁcant effect on the total amount of microsomal cytochrome P450, but it caused a signiﬁcant increase in the cytochrome P450 isoforms CYPs 1A1 and 1A2. It also signiﬁcantly increased the concentrations of some metabolites of theophylline. These results suggest that RS has the potential to interact with other drugs that are biotransformed by cytochrome P450, when given concomitantly with it. Copyright © 2003 John Wiley & Sons, Ltd.
Pharmacological effects of extracts from Valeriana adscendens Trel. II. Effects on GABA uptake and amino acids
Authors: De Feo Vincenzo , Faro Carlos 
Published: June 2003

AbstractMethanolic and aqueous extracts from Valeriana adscendens (Valerianaceae), that previously demonstrated neuroleptic‐like properties, were studied for their effects on GABA uptake and amino acid neurotransmitter levels. The methanolic estract showed a significant effect in inhibiting GABA uptake and in decreasing the intracellular content of amino acid neurotransmitters in crude synaptosomes of rat. The data obtained could explain the neuroleptic activity of methanolic extract of the plant and confirm its traditional use. Copyright © 2003 John Wiley & Sons, Ltd.
Hepatoprotective effect of the extract and isocytisoside from Aquilegia vulgaris
Authors: Adamska T. , Młynarczyk W. , Jodynis‐Liebert J. , Bylka W. , Matławska I. 
Published: June 2003

AbstractThe hepatoprotective effect of the ethanol extract (AvEE) and the main ﬂavonoid compound 4′‐methoxy‐5,7‐dihydroxyﬂavone 6‐C‐β‐glucopyranoside (isocytisoside, ISOC) from the leaves and stems of Aquilegia vulgaris L. were studied using the CCl4‐induced hepatotoxicity test.The acute toxicity test in mice showed that AvEE can be classiﬁed as nontoxic since a dose of 3000 mg/ kg did not cause mortality.The barbiturate‐induced sleeping time prolonged by CCl4 administration to mice was signiﬁcantly reduced after AvEE treatment proving the protective effect of the extract on microsomal drug‐metabolizing enzymes.AvEE and ISOC administered to rats 48 h, 24 h and 2 h before, and 6 h after CCl4 intoxication caused a signiﬁcant decrease in the CCl4‐induced elevation of hepatic enzymes activity in serum, i.e. sorbitol dehydrogenase (SDH), glutamate oxaloacetate and glutamate pyruvate transaminases (GOT, GPT).Both substances induced CCl4‐diminished erythrocyte superoxide dismutase (SOD) and reduced the activities of glutathione peroxidase (GPx) and glutathione reductase (GR) preliminarily enhanced by CCl4.The hepatoprotective properties of AvEE and ISOC were conﬁrmed by pathomorphological examination of the liver. Copyright © 2003 John Wiley & Sons, Ltd.
Designing an accelerated degradation experiment by optimizing the estimation of the percentile
Authors: Yu Hong‐Fwu 
Published: June 2003

AbstractDegradation tests are widely used to assess the reliability of highly reliable products which are not likely to fail under traditional life tests or accelerated life tests. However, for some highly reliable products, the degradation may be very slow and hence it is impossible to have a precise assessment within a reasonable amount of testing time. In such cases, an alternative is to use higher stresses to extrapolate the product's reliability at the design stress. This is called an accelerated degradation test (ADT). In conducting an ADT, several decision variables, such s the inspection frequency, sample size and termination time, at each stress level are influential on the experimental efficiency. An inappropriate choice of these decision variables not only wastes experimental resources but also reduces the precision of the estimation of the product's reliability at the use condition. The main purpose of this paper is to deal with the problem of designing an ADT. By using the criterion of minimizing the mean‐squared error of the estimated 100$p$th percentile of the product's lifetime distribution at the use condition subject to the constraint that the total experimental cost does not exceed a predetermined budget, a nonlinear integer programming problem is built to derive the optimal combination of the sample size, inspection frequency and the termination time at each stress level. A numerical example is provided to illustrate the proposed method. Copyright © 2003 John Wiley & Sons, Ltd.
Determining the lifetime of CD‐RWs using efficient sampling on a production line
Authors: Chen Chie‐Bein 
Published: June 2003

AbstractThis work derives the intermittent batch size and sample size for product life testing on a production line. The sequential probability ratio test was adopted to determine the sample size, $n$, and the expected number of samples (ENS). An inverse chi‐square approximation was used to determine the relationship between the degree of freedom, $m-1$, and the estimated range of $\sigma^2$ $(ER\,\sigma^2)$ at various $(1-\alpha)$ levels of confidence. Consequently, ENS and $m$ were used to determine the intermittent batch size, $l$. Finally, rewritable compact disks (CD‐RWs) underwent testing to demonstrate the feasibility and effectiveness of the proposed efficient sampling approach. Copyright © 2003 John Wiley & Sons, Ltd.
An alternative desirability function for achieving ‘six sigma’ quality
Authors: Ribardo Charles , Allen Theodore T. 
Published: June 2003

AbstractTo achieve high process yields or ‘six sigma’ quality, engineers often need to evaluate and optimize processes that are characterized by multiple quality characteristics. Existing desirability functions weigh together multiple objectives but they have a number of limitations. Most importantly, available desirability functions do not explicitly account for the combined effect of the mean and the dispersion of the quality characteristic. Therefore, it is easy to incur excessive expenditures or unknowingly to fail to achieve targeted yields. In this paper, a desirability function is proposed that addresses these limitations. This function conservatively estimates the ‘effective yield’ under assumptions described in the ‘six sigma’ literature. We use an arc‐welding application to illustrate how the proposed desirability function can yield a substantially higher level of quality as well as a more accurate assessment of the process capability than available alternatives. We suggest that the proposed desirability function should be used to facilitate multicriterion optimization when dispersion data are available. Copyright © 2003 John Wiley & Sons, Ltd.
Reliability analysis of electronic devices with multiple competing failure modes involving performance aging degradation
Authors: Huang Wei , Askin Ronald G. 
Published: June 2003

AbstractThis paper presents an extension of reliability analysis of electronic devices with multiple competing failure modes involving performance aging degradation. The probability that a product fails on a specific mode is derived. Using this probability, the dominant failure mode on the product can be predicted. A practical example is presented to analyze an electronic device with two kinds of major failure modes–solder/Cu pad interface fracture (a catastrophic failure) and light intensity degradation (a degradation failure). Reliability modeling of an individual failure mode and device reliability analysis is presented and results are discussed. Copyright © 2003 John Wiley & Sons, Ltd.