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Berlin Brandenburg


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  • Kaiser, Rolf  (25)
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  • 1
    In: IEEE Intelligent Systems, Nov-Dec, 2001, Vol.16(6), p.35(7)
    Description: An intelligent system, called geno2pheno, relies on information derived from the HIV genomic sequence to predict the virus's resistance . Geno2pheno uses decision tree classifiers and support vector machines to make its predictions.
    Keywords: Hiv Tests -- Research ; Biomedical Engineering -- Research ; Genomics -- Research
    ISSN: 1541-1672
    E-ISSN: 19411294
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  • 2
    In: Bioinformatics, 2003, Vol.19(1), pp.16-25
    Description: Motivation: Despite some progress with antiretroviral combination therapies, therapeutic success in the management of HIV-infected patients is limited. The evolution of drug-resistant genetic variants in response to therapy plays a key role in treatment failure and finding a new potent drug combination after therapy failure is considered challenging. Results: To estimate the activity of a drug combination against a particular viral strain, we develop a scoring function whose independent variables describe a set of antiviral agents and viral DNA sequences coding for the molecular targets of the respective drugs. The construction of this activity score involves (1) predicting phenotypic drug resistance from genotypes for each drug individually, (2) probabilistic modeling of predicted resistance values and integration into a score for drug combinations, and (3) searching through the mutational neighborhood of the considered strain in order to estimate activity on nearby mutants. For a clinical data set, we determine the optimal search depth and show that the scoring scheme is predictive of therapeutic outcome. Properties of the activity score and applications are discussed. Contact: beerenwinkel@mpi-sb.mpg.de Keywords: HIV, antiretroviral therapy, drug resistance, SVM regression, therapy optimization, sequence space search.
    Keywords: Biology;
    ISSN: 1367-4803
    E-ISSN: 1460-2059
    E-ISSN: 13674811
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  • 3
    Language: English
    In: Clinical cancer research : an official journal of the American Association for Cancer Research, 01 January 2010, Vol.16(1), pp.311-9
    Description: BIBF 1120 is an oral, potent angiokinase inhibitor targeting receptors of the vascular endothelial growth factors, platelet-derived growth factors, and fibroblast growth factors. This phase I, accelerated titration study assessed the maximum tolerated dose, safety, pharmacokinetics, and pharmacodynamic effects of BIBF 1120. Sixty-one patients with advanced cancers received BIBF 1120 in successive cohorts. Twenty-five received 50 to 450 mg once daily and 36 received 150 to 300 mg twice daily in 4-week treatment courses interspersed by 1 week of washout. Dynamic contrast-enhanced magnetic resonance imaging assessed antiangiogenic effect in 42 patients. Most frequent BIBF 1120-related adverse events were mostly mild to moderate (Common Toxicity Criteria grade 1-2) nausea (68.9%), vomiting (45.9%), and diarrhea (44.3%). The majority of dose-limiting adverse events of Common Toxicity Criteria grade 3 or 4 were reversible liver enzyme elevations. The maximum tolerated dose was 250 mg of BIBF 1120 for once and twice daily dosing. BIBF 1120 was absorbed moderately fast (t(max) = 1-3 hours at steady state), with no deviation from dose linearity and no decrease of exposure over time. The gMean terminal half-life was from 13 to 19 hours. One complete and two partial responses occurred in patients with renal cell cancer (n = 2) and colorectal cancer (n = 1). Dynamic contrast-enhanced magnetic resonance imaging showed a significant reduction in tumor blood flow in 55% of evaluable patients. BIBF 1120 dosed continuously displayed a favorable safety and pharmacokinetics profile, and first efficacy signals were observed. Twice daily dosing permitted increased drug exposure without additional toxicity. Two hundred milligrams BIBF 1120 twice daily is the recommended dose for phase II monotherapy studies.
    Keywords: Angiogenesis Inhibitors -- Therapeutic Use ; Antineoplastic Agents -- Therapeutic Use ; Indoles -- Therapeutic Use ; Neoplasms -- Drug Therapy
    ISSN: 1078-0432
    E-ISSN: 15573265
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  • 4
    Language: English
    In: Proceedings of the National Academy of Sciences of the United States of America, 11 June 2002, Vol.99(12), pp.8271-6
    Description: Drug resistance testing has been shown to be beneficial for clinical management of HIV type 1 infected patients. Whereas phenotypic assays directly measure drug resistance, the commonly used genotypic assays provide only indirect evidence of drug resistance, the major challenge being the interpretation of the sequence information. We analyzed the significance of sequence variations in the protease and reverse transcriptase genes for drug resistance and derived models that predict phenotypic resistance from genotypes. For 14 antiretroviral drugs, both genotypic and phenotypic resistance data from 471 clinical isolates were analyzed with a machine learning approach. Information profiles were obtained that quantify the statistical significance of each sequence position for drug resistance. For the different drugs, patterns of varying complexity were observed, including between one and nine sequence positions with substantial information content. Based on these information profiles, decision tree classifiers were generated to identify genotypic patterns characteristic of resistance or susceptibility to the different drugs. We obtained concise and easily interpretable models to predict drug resistance from sequence information. The prediction quality of the models was assessed in leave-one-out experiments in terms of the prediction error. We found prediction errors of 9.6-15.5% for all drugs except for zalcitabine, didanosine, and stavudine, with prediction errors between 25.4% and 32.0%. A prediction service is freely available at http://cartan.gmd.de/geno2pheno.html.
    Keywords: Genetic Variation ; Drug Resistance, Viral -- Physiology ; HIV-1 -- Drug Effects
    ISSN: 0027-8424
    E-ISSN: 10916490
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  • 5
    Language: English
    In: BMC cancer, 11 July 2014, Vol.14, pp.510
    Description: Nintedanib is a potent, oral angiokinase inhibitor that targets VEGF, PDGF and FGF signalling, as well as RET and Flt3. The maximum tolerated dose of nintedanib was evaluated in a phase I study of treatment-refractory patients with advanced solid tumours. In this preplanned subanalysis, the effect of nintedanib on the tumour vasculature, along with efficacy and safety, was assessed in 30 patients with colorectal cancer (CRC). Patients with advanced CRC who had failed conventional treatment, or for whom no therapy of proven efficacy existed, were treated with nintedanib ranging from 50-450 mg once-daily (n = 14) or 150-250 mg twice-daily (n = 16) for 28 days. After a 1-week rest, further courses were permitted in the absence of progression or undue toxicity. The primary objective was the effect on the tumour vasculature using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and expressed as the initial area under the DCE-MRI contrast agent concentration-time curve after 60 seconds (iAUC60) or the volume transfer constant between blood plasma and extravascular extracellular space (Ktrans). Patients received a median of 4.0 courses (range: 1-13). Among 21 evaluable patients, 14 (67%) had a ≥40% reduction from baseline in Ktrans and 13 (62%) had a ≥40% decrease from baseline in iAUC60, representing clinically relevant effects on tumour blood flow and permeability, respectively. A ≥40% reduction from baseline in Ktrans was positively associated with non-progressive tumour status (Fisher's exact: p = 0.0032). One patient achieved a partial response at 250 mg twice-daily and 24 (80%) achieved stable disease lasting ≥8 weeks. Time to tumour progression (TTP) at 4 months was 26% and median TTP was 72.5 days (95% confidence interval: 65-114). Common drug-related adverse events (AEs) included nausea (67%), vomiting (53%) and diarrhoea (40%); three patients experienced drug-related AEs ≥ grade 3. Four patients treated with nintedanib once-daily had an alanine aminotransferase and/or aspartate aminotransferase increase ≥ grade 3. No increases 〉 grade 2 were seen in the twice-daily group. Nintedanib modulates tumour blood flow and permeability in patients with advanced, refractory CRC, while achieving antitumour activity and maintaining an acceptable safety profile.
    Keywords: Antineoplastic Agents -- Administration & Dosage ; Colorectal Neoplasms -- Blood Supply ; Indoles -- Administration & Dosage
    E-ISSN: 1471-2407
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  • 6
    In: Journal of Antimicrobial Chemotherapy, 2015, Vol. 70(3), pp.930-940
    Description: OBJECTIVES: It is still debated if pre-existing minority drug-resistant HIV-1 variants (MVs) affect the virological outcomes of first-line NNRTI-containing ART.METHODS: This Europe-wide case-control study included ART-naive subjects infected with drug-susceptible HIV-1 as revealed by population sequencing, who achieved virological suppression on first-line ART including one NNRTI. Cases experienced virological failure and controls were subjects from the same cohort whose viraemia remained suppressed at a matched time since initiation of ART. Blinded, centralized 454 pyrosequencing with parallel bioinformatic analysis in two laboratories was used to identify MVs in the 1%-25% frequency range. ORs of virological failure according to MV detection were estimated by logistic regression.RESULTS: Two hundred and sixty samples (76 cases and 184 controls), mostly subtype B (73.5%), were used for the analysis. Identical MVs were detected in the two laboratories. 31.6% of cases and 16.8% of controls harboured pre-existing MVs. Detection of at least one MV versus no MVs was associated with an increased risk of virological failure (OR = 2.75, 95% CI = 1.35-5.60, P = 0.005); similar associations were observed for at least one MV versus no NRTI MVs (OR = 2.27, 95% CI = 0.76-6.77, P = 0.140) and at least one MV versus no NNRTI MVs (OR = 2.41, 95% CI = 1.12-5.18, P = 0.024). A dose-effect relationship between virological failure and mutational load was found.CONCLUSIONS: Pre-existing MVs more than double the risk of virological failure to first-line NNRTI-based ART.
    Keywords: Minority Drug - Resistant Hiv - 1 Variants ; Chain ; Antiretroviral Therapy ; European Multicentre Study
    ISSN: 0305-7453
    E-ISSN: 1460-2091
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  • 7
    Language: English
    In: Xenobiotica, 01 April 2011, Vol.41(4), pp.297-311
    Description: The pharmacokinetics and metabolism of BIBF 1120, an oral triple angiokinase inhibitor targeting vascular endothelial growth factor receptor (VEGFR), platelet-derived growth factor receptor (PDGFR), and fibroblast growth factor receptor (FGFR),...
    Keywords: Bibf 1120 ; Pharmacokinetic Profile ; Metabolism ; Pharmacy, Therapeutics, & Pharmacology ; Chemistry
    ISSN: 0049-8254
    E-ISSN: 1366-5928
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  • 8
    In: JAIDS Journal of Acquired Immune Deficiency Syndromes, 2011, Vol.56(2), pp.109-117
    Description: BACKGROUND:: HIV-1 protease is subjected to dual selection pressure exerted by protease inhibitors (PIs) and cytotoxic T lymphocytes (CTL). Recently, we identified KMIGGIGGF (KF9) as a HLA-B*1501-restricted CTL epitope, including several major PI resistance mutations (M46I/L, I47A/V, G48V, I50V). To assess potential interactions between KF9-specific CTL and emergence of these important resistance mutations, we studied CTL recognition of the mutations and analyzed protease sequences in an HLA-I-typed patient cohort. METHODS:: CTL recognition of KF9 and resistance mutations in KF9 were studied in 38 HLA-B*1501-positive HIV-1-infected patients using variant KF9 peptides in interferon-γ enzyme-linked immunospot assays. Protease sequences were analyzed in 302 HLA-I-typed HIV-1-infected patients. RESULTS:: G48V abolished KF9 recognition by CTL in all patients. Furthermore, M46I, I47A, and I50V could impair or abolish CTL recognition in many patients. In contrast, M46L and I47V showed good CTL recognition in nearly all patients. HIV-1 protease sequence analysis showed no statistical correlation between the occurrence of resistance mutations in KF9 and HLA-B*1501. Viral load in patients failing therapy with KF9 mutations was significantly lower in HLA-B*1501-positive patients in comparison with HLA-B*1501-negative patients. CONCLUSIONS:: PI mutations, G48V, M46I, and I47A, can abrogate CTL recognition, indicating potential interactions between development of drug resistance and CTL response. However, we could not find evidence that development of these PI mutations is influenced by KF9-specific CTL.
    Keywords: Histocompatibility Antigen HLA ; Interferon ; Enzyme-Linked Immunosorbent Assay ; Cytotoxicity ; Statistics ; Drug Resistance ; Proteinase Inhibitors ; Lymphocytes T ; Mutation ; Epitopes ; Human Immunodeficiency Virus 1 ; Microorganisms & Parasites;
    ISSN: 1525-4135
    E-ISSN: 19447884
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  • 9
    Language: English
    In: Journal of Virological Methods, December 2016, Vol.238, pp.29-37
    Description: Phenotypic resistance analysis is an indispensable method for determination of HIV-1 resistance and cross-resistance to novel drug compounds. Since integrase inhibitors are essential components of recent antiretroviral combination therapies, phenotypic resistance data, in conjunction with the corresponding genotypes, are needed for improving rules-based and data-driven tools for resistance prediction, such as HIV-Grade and geno2pheno . For generation of phenotypic resistance data to recent integrase inhibitors, a recombinant phenotypic integrase susceptibility assay was established. For validation purposes, the phenotypic resistance to raltegravir, elvitegravir and dolutegravir of nine subtype-B virus strains, isolated from integrase inhibitor-naïve and raltegravir-treated patients was determined. Genotypic resistance analysis identified four virus strains harbouring RAL resistance-associated mutations. Phenotypic resistance analysis was performed as follows. The HIV-1 integrase genes were cloned into a modified pNL4-3 vector and transfected into 293T cells for the generation of recombinant virus. The integrase-inhibitor susceptibility of the recombinant viruses was determined via an indicator cell line. While raltegravir resistance profiles presented a high cross-resistance to elvitegravir, dolutegravir maintained activity in spite of the Y143R and N155H mutations, confirming the strong activity of dolutegravir against raltegravir-resistant viruses. Solely a Q148H + G140S variant presented reduced susceptibility to dolutegravir. In conclusion, our phenotypic susceptibility assay permits resistance analysis of the integrase gene of patient-derived viruses for integrase inhibitors by replication-competent recombinants. Thus, this assay can be used to analyze phenotypic drug resistance of integrase inhibitors . It provides the possibility to determine the impact of newly appearing mutational patterns to drug resistance of recent integrase inhibitors.
    Keywords: HIV-1 ; Integrase ; Phenotypic Resistance ; Geno2pheno ; Cross-Resistance ; Dolutegravir ; Biology
    ISSN: 0166-0934
    E-ISSN: 1879-0984
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  • 10
    Language: English
    In: Journal of Clinical Virology, 2011, Vol.50(2), pp.156-161
    Description: Minority drug-resistant HIV-1 variants, undetected by conventional genotyping, may impair the outcome of antiretroviral therapy (ART). Thus, we retrospectively analyzed the prevalence of minority drug-resistant HIV-1 variants before ART in chronically HIV-1 infected patients initiating first-line therapy and assessed the impact on clinical outcome in the prospective German Truvada cohort. Samples from 146 antiretroviral treatment-naïve patients were collected between April 2005 and August 2006. K65R, K103N, and M184V variants at low frequencies were detected by allele-specific real-time PCR. Minority drug-resistant HIV-1 variants were detected in 20/146 patients (13.7%): the M184V mutation in 12/146 patients (8.2%), the K103N mutation in 8/146 patients (5.5%), and the K65R mutation in 4/146 patients (2.7%). Four patients with the M184V mutation also harbored the K65R or the K103N mutation. The 12- and 24 months virological efficacy data revealed that the rate of treatment failure was not increased in the group of patients harboring minority drug-resistant HIV-1 variants prior to ART. Minority drug-resistant HIV-1 variants can be frequently detected in treatment-naïve, chronically HIV-1 infected patients. Despite the presence of those mutations as minority variants before initiating ART, most of the patients were successfully treated.
    Keywords: HIV-1 ; Art ; Drug Resistance ; Minority Drug-Resistant HIV-1 Variants ; Allele-Specific Real-Time Pcr ; Treatment Failure ; Biology
    ISSN: 1386-6532
    E-ISSN: 1873-5967
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