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Biomedical subjects

W Wurst

Publications and source records attributed to W Wurst.

At least 73 records · Page 4Linked to original sources
PubMed1996

Lack of pharmacokinetic interaction between pantoprazole and diclofenac.

The new H+/K+ ATPase inhibitor pantoprazole is extensively metabolized by the liver. As substituted benzimidazoles may potentially interact with the cytochrome P450 system, the influence of pantoprazole on the pharmacokinetics of the NSAID diclofenac was investigated. Diclofenac is widely used in the treatment of rheumatic diseases and is mainly metabolized in the liver by CYP2C9. Twenty-four healthy volunteers (13 male/11 female) completed a randomized crossover study. As test they received orally 40 mg pantoprazole and concomitantly 100 mg diclofenac. As respective references 100 mg diclofenac or 40 mg pantoprazole were given alone. Diclofenac and pantoprazole serum concentrations were measured. Lack of pharmacokinetic interaction was handled as an equivalence problem. The 90% confidence intervals (CI) of the ratios of the primary characteristic AUC and the secondary characteristic C(max) of diclofenac were entirely within the equivalence range of 0.8 - 1.25. Hence, no influence of pantoprazole on the pharmacokinetics of diclofenac was concluded, either by competition with the CYP2C9 or by the reduction of gastric acid secretion. Vice versa, diclofenac did not affect the pharmacokinetics of pantoprazole. All treatments were safe and well tolerated. No dose adjustment is required during concomitant treatment with diclofenac and pantoprazole.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1996

Pantoprazole has no influence on steady state pharmacokinetics and pharmacodynamics of metoprolol in healthy volunteers.

The new H+/K+ ATPase inhibitor pantoprazole, a substituted benzimidazole, is metabolized by the hepatic cytochrome P450 enzymes 2C19 or 3A4 and subsequently undergoes phase II metabolism. The widely used beta 1-adrenoreceptor-blocking agent metoprolol is metabolized via CYP2D6. The influence of pantoprazole on the pharmacokinetics of an orally administered zero order kinetics formulation (ZOK) of metoprolol was the objective of this study. Eighteen volunteers (9 female, 9 male, age 20-44 years) completed the randomized, double-blind crossover study. Each subject received either 95 mg metoprolol and placebo (reference (R)) or 95 mg metoprolol and 40 mg pantoprazole (test (T)) as oral doses (sid) for 5 consecutive days. On day 5 of each period serum concentrations of R- and S-metoprolol were determined and a treadmill ergometry was performed. The primary pharmacokinetic characteristics for extent and rate of absorption were AUC(0-24h) and % PTF, respectively. To assess the pharmacodynamic effect of metoprolol the excess area under the effect vs. time curve was calculated for heart rate during ergometry (AUCexHR). Point estimate and 90% confidence limits (CI) for the ratios of population medians of T and R were given. The respective point estimates (90% CI) of the ratios of both primary and secondary characteristics were entirely within the equivalence range of 0.80 and 1.25 for both enantiomers of metoprolol. Moreover, equivalence could be shown for the pharmacodynamic characteristic AUCexHR. Hence, it was concluded that pantoprazole does not interact with metoprolol pharmacokinetics or pharmacodynamics. Therefore, no dose adjustment of metoprolol during therapy with pantoprazole is necessary.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1996

Pantoprazole does not interact with nifedipine in man under steady-state conditions.

The new H+/K+ -ATPase inhibitor pantoprazole is extensively metabolized by the liver. As substituted benzimidazoles can interact with the cytochrome P450 system, the influence of pantoprazole on the steady-state pharmacokinetics of the calcium antagonist nifedipine was investigated. Nifedipine is widely used in the treatment of cardiovascular diseases and is mainly metabolized in the liver by CYP3A4. Additionally possible influence of gastric pH on the absorption of nifedipine is discussed. Twenty-four healthy volunteers (13 m/11 f) completed a randomized crossover study. As test they received orally 40 mg pantoprazole s.i.d. for 10 days and concomitantly 20 mg nifedipine sustained release (SR) b.i.d. from day 6 to 10. During the reference period 20 mg nifedipine SR were dosed b.i.d. for 5 days. Nifedipine and pantoprazole serum concentrations were measured over one dosing interval on the last day of each period. Lack of pharmacokinetic interaction was handled as an equivalence problem. The 90%-confidence intervals (CI) of the ratios of the primary characteristics AUC and Cmax of nifedipine were entirely within the equivalence range of 0.8 - 1.25. Hence no influence of pantoprazole on the pharmacokinetics of nifedipine was concluded, either by competition with the CYP3A4 or by the reduction of gastric acid secretion. As secondary criterion nifedipine had no relevant influence on the pantoprazole pharmacokinetic characteristics. All treatments were safe and well tolerated. No dose adjustment is required during concomitant treatment with nifedipine and pantoprazole.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1995

Rescue of the En-1 mutant phenotype by replacement of En-1 with En-2.

The related mouse Engrailed genes En-1 and En-2 are expressed from the one- and approximately five-somite stages, respectively, in a similar presumptive mid-hindbrain domain. However, mutations in En-1 and En-2 produce different phenotypes. En-1 mutant mice die at birth with a large mid-hindbrain deletion, whereas En-2 mutants are viable, with cerebellar defects. To determine whether these contrasting phenotypes reflect differences in temporal expression or biochemical activity of the En proteins, En-1 coding sequences were replaced with En-2 sequences by gene targeting. This rescued all En-1 mutant defects, demonstrating that the difference between En-1 and En-2 stems from their divergent expression patterns.

Animals↗
PubMed1995

Tolerance, safety, and kinetics of the new antineoplastic compound dexniguldipine-HCl after oral administration: a phase I dose-escalation trial.

Dexniguldipine-HCl is a new dihydropyridine compound that exerts selective antiproliferative activity in a variety of tumor models and, in addition, has a high potency in overcoming multidrug resistance. The purpose of this trial was to determine the toxicity and pharmacokinetics of dexniguldipine and to establish a recommended dose for phase II trials. A total of 37 patients with cancer were treated with oral dexniguldipine in increasing doses for up to 7 days. The main parameters evaluated were subjective tolerance and laboratory and cardiovascular parameters (blood pressure and ECG). Blood samples were drawn for analysis of the drug's pharmacokinetics. Dizziness and nausea were the major adverse events observed in seven patients, but episodes were generally mild and not clearly dose-related. Vomiting occurred in one patient. Hypotensive effects and orthostatic dysregulation were observed in some patients but were not considered to be dose-limiting. Therefore, no dose-limiting toxicity was found and the maximally tolerable dose could not be determined. Pharmacokinetic data showed wide interindividual variation and a dose-dependent increase in steady-state serum concentrations at doses of up to 1,000 mg daily, with no clear further increase being observed at higher doses. Consistently high concentrations were achieved with the 2,500-mg dose. Despite the lack of dose-limiting toxicity, higher doses of dexniguldipine do not appear to be useful for clinical evaluation because of the pharmacokinetic properties of the compound: therefore, 2,500 mg/day is recommended as the daily dose for phase II trials.

Administration, Oral↗
PubMed1995

A large-scale gene-trap screen for insertional mutations in developmentally regulated genes in mice.

We have used a gene-trap vector and mouse embryonic stem (ES) cells to screen for insertional mutations in genes developmentally regulated at 8.5 days of embryogenesis (dpc). From 38,730 cell lines with vector insertions, 393 clonal integrations had disrupted active transcription units, as assayed by beta-galactosidase reporter gene expression. From these lines, 290 clones were recovered and injected into blastocysts to assay for reporter gene expression in 8.5-dpc chimeric mouse embryos. Of these, 279 clones provided a sufficient number of chimeric embryos for analysis. Thirty-six (13%) showed restricted patterns of reporter-gene expression, 88 (32%) showed widespread expression and 155 (55%) failed to show detectable levels of expression. Further analysis showed that approximately one-third of the clones that did not express detectable levels of the reporter gene at 8.5 dpc displayed reporter gene activity at 12.5 dpc. Thus, a large proportion of the genes that are expressed in ES cells are either temporally or spatially regulated during embryogenesis. These results indicate that gene-trap mutageneses in embryonic stem cells provide an effective approach for isolating mutations in a large number of developmentally regulated genes.

Animals↗
PubMed1995

Phase I: transcranial echo contrast studies in healthy volunteers.

BACKGROUND AND PURPOSE: Transcranial ultrasound diagnostics are particularly hindered by insufficient ultrasound penetration through the temporal bone. The use of ultrasonic contrast media to enhance the Doppler signal is an important step toward the solution of this problem. In the present study we investigated the tolerability and the diagnostic value of a new intravenous transpulmonary ultrasonic contrast medium, BY963. METHODS: In two phase I studies, 8 healthy volunteers received a spherosome suspension containing a phospholipid as the active ingredient. The intravenous injection was performed in three doses (2.5, 5, and 10 mL) at four different injection rates (0.25, 0.5, and 1 mL/s and bolus). The duration and degree of the signal enhancement were measured by two transcranial ultrasonic procedures presently used in clinical practice: transcranial Doppler sonography (TCD) and transcranial color-coded sonography (TCCS). The assessment of tolerability was based on chemical laboratory parameters and hemodynamic data (heart rate, blood pressure, electrocardiogram) and on questionnaires relating to general well-being. RESULTS: BY963 was tolerated without complications. All 38 administrations of the echo contrast medium produced a marked increase in the TCD signal (> 30 dB) in the intracranial basal cerebral arteries. To obtain the optimum time window for diagnostic use, higher doses with slower injection rates are advantageous. The duration of optimal contrasting was 42 to 68 seconds (TCD) and 12 to 132 seconds (TCCS), depending on the method and mode of administration. Bolus injections gave rise to an increased incidence of color artifacts. CONCLUSIONS: BY963 significantly improves intracranial Doppler imaging while being well tolerated. The signal enhancement lasts long enough for TCCS to display all basal cerebral arteries after just one injection.

Adult↗
PubMed1995

Lack of interaction between pantoprazole and digoxin at therapeutic doses in man.

Substituted benzimidazole inhibitors of the gastric H+/K+ATPase may interact with the cytochrome P450 enzyme system and alter the pharmacokinetics of coadministered drugs. On the other hand, changes in intragastric pH might alter the absorption of other drugs. The primary aim of the present study was to determine whether pantoprazole modifies the steady-state serum concentrations of orally administered digoxin. Secondary aims were the influence of digoxin on the pharmacokinetics of pantoprazole as well as safety and tolerability. Eighteen healthy volunteers received a single oral dose of pantoprazole (40 mg) and serum concentrations were determined. Three to 10 days later, subjects received in a single-blind, randomized, crossover fashion oral beta-acetyldigoxin (0.2 mg) twice daily and concomitant oral pantoprazole (40 mg) or placebo once daily for 5 days. Serum concentrations of pantoprazole and digoxin were determined on day 5. Primary characteristics for confirmative assessment of no interaction were AUC and Cmax of digoxin. Lack of interaction in the sense of equivalence was concluded for both digoxin (with and without pantoprazole) and pantoprazole (with and without digoxin) as the 90%-confidence intervals of the respective AUC- and Cmax-ratios were within the equivalence range of 0.8-1.25. Pantoprazole did not influence the characteristic ECG modifications (T-wave) caused by digoxin. Both drugs were well tolerated and no adverse events or clinically relevant alterations in vital signs or clinical laboratory parameters were observed during treatment. In conclusion, pantoprazole and digoxin may be administered concomitantly without the need for dose adjustment.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1995

Bioavailability and pharmacokinetic characteristics of dexniguldipine-HCl, a new anticancer drug.

Dexniguldipine-HCl is a new dihydropyridine derivative with antineoplastic activity and potency for overcoming multidrug resistance. In this pharmacokinetic study the bioavailability of 3 doses of an oral formulation of dexniguldipine was to be determined. Fourteen patients with malignant disease not eligible for higher priority treatment and sufficient general condition were included. In 12 patients all pharmacokinetic investigations were available for evaluation. A single 4-h infusion of 2 mg per kg body weight of dexniguldipine was given as reference. Thereafter 3 increasing oral dosages (750, 1,500, 2,250 mg/d) were given on a 3-time daily basis for 3 consecutive weeks. On day 7 (under steady state conditions) of each period, a pharmacokinetic profile was done. Absolute bioavailability at the 3-dose levels was 3, 4, and 5%, respectively, thus slightly increasing with dose, but generally low. After intravenous administration terminal half life was 22.4 h, clearance 36.9 l/h and volume of distribution 1,193 1. Toxicity was tolerable with main adverse events being loss of appetite, nausea, and vomiting. Cardiovascular effects and a decrease in serum calcium were reported in several patients. Patients were allowed to continue treatment if a benefit was expected, and 2 patients showed tumor regression during treatment. One patient with renal cell carcinoma achieved a partial remission. Bioavailability of this oral formulation seems too low for routine clinical use, despite the fact that clinical effects have been observed.

Administration, Oral↗
PubMed1994

Abnormal embryonic cerebellar development and patterning of postnatal foliation in two mouse Engrailed-2 mutants.

The cerebellum is an ideal system to study pattern formation in the central nervous system because of its simple cytoarchitecture and regular organization of folds and neural circuitry. Engrailed-2 (En-2) is expressed in a spatially restricted broad band around the mesencephalic-metencephalic junction, a region from which the cerebellum is derived. Mice homozygous for a targeted deletion of the En-2 homeobox, En-2hd, previously have been shown to have an altered adult cerebellar foliation pattern. To address whether the En-2hd allele was hypomorphic, we generated a putative null mutation that makes an N-terminal deletion (ntd). Mice homozygous for this new mutation, En-2ntd, display an identical cerebellar patterning defect, suggesting that both alleles represent null alleles. We also examined the developmental profile of En-2 homozygous mutant cerebellar foliation. This revealed a complex phenotype of general developmental delay and abnormal formation of specific fissures with the most severe morphological disruptions being limited to the posterior region of the cerebellum. The expression of two transgenes, which express lacZ in lobe-specific patterns in the cerebellum, also was found to be altered in En-2 homozygotes, suggesting possible lobe transformations. Finally, during embryogenesis there was a clear delay in fusion of the cerebellar rudiments at the midline by 15.5 d.p.c. This and the expression pattern of En-2 suggests that although cerebellar foliation is largely a postnatal process, the patterning of the cerebellum may begin during embryogenesis and that En-2 plays a critical role in this early process.

Animals↗
PubMed1994

Multiple developmental defects in Engrailed-1 mutant mice: an early mid-hindbrain deletion and patterning defects in forelimbs and sternum.

During mouse development, the homeobox-containing gene En-1 is specifically expressed across the mid-hindbrain junction, the ventral ectoderm of the limb buds, and in regions of the hindbrain, spinal cord, somites and somite-derived tissues. To address the function of En-1 during embryogenesis, we have generated mice homozygous for a targeted deletion of the En-1 homeobox. En-1 mutant mice died shortly after birth and exhibited multiple developmental defects. In the brains of newborn mutants, most of the colliculi and cerebellum were missing and the third and fourth cranial nerves were absent. A deletion of midhindbrain tissue was observed as early as 9.5 days of embryonic development and the phenotype resembles that previously reported for Wnt-1 mutant mice. In addition, patterning of the forelimb paws and sternum was disrupted, and the 13th ribs were truncated. The results of these studies suggest a cell autonomous role for En-1 in generation and/or survival of mid-hindbrain precursor cells and also a non-cell autonomous role in signalling normal development of the limbs and possibly sternum.

Animals↗
PubMed1994

Lack of pantoprazole drug interactions in man.

This review summarizes the results of pharmacokinetic and pharmacodynamic drug interaction studies in man with pantoprazole, a new, selective proton pump inhibitor. Different mechanisms have to be considered as causes for potential drug-drug interactions. Proton pump inhibitors (PPIs) in general may alter the absorption of drugs by increasing the intragastric pH. Due to the presence of an imidazole ring, the PPIs of the class of substituted benzimidazole sulfoxides may interfere with the metabolism of other drugs by altering the activity of drug metabolizing enzymes of the cytochrome P450 system, via either induction or inhibition. With the increasing use of PPIs, their interaction potential gains therapeutic importance as was the case with the first and second generation of H2-blockers (cimetidine and ranitidine, respectively). The enhanced selectivity of pantoprazole to the gastric H+/K(+)-ATPase characterizes the new PPI generation. In comparison to omeprazole and lansoprazole, pantoprazole showed a much lower affinity to cytochrome P450 in vitro and a markedly lower potency in the in vivo rat model for interaction with diazepam. In contrast to omeprazole, pantoprazole does not interact with the cytochrome P450 system in man. In the drug interaction studies conducted so far, pantoprazole did not affect the pharmacokinetics or pharmacodynamics of antipyrine, diazepam, digoxin, a hormonal contraceptive, nifedipine, phenytoin, theophylline and warfarin in man. Also pantoprazole neither induced the drug metabolism of antipyrine nor increased urinary excretion of the induction markers D-glucaric acid and 6 beta-hydroxycortisol. Vice versa, the investigated drugs had no relevant influence on the pharmacokinetics of pantoprazole.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1994

Pantoprazole lacks interaction with antipyrine in man, either by inhibition or induction.

Substituted benzimidazole inhibitors of the gastric H+/K(+)-ATPase may interact with the cytochrome P450 enzyme system and alter the pharmacokinetics of coadministered drugs, as known for omeprazole. The primary aim of the present studies was to determine whether pantoprazole, a new, selective proton pump inhibitor, modifies the plasma concentrations of orally-administered antipyrine, a commonly used marker for mixed hepatic oxidase enzyme activity. In the acute study, 12 healthy male volunteers were given a) a single 30 mg i.v. doses of pantoprazole, b) a single 5 mg/kg oral dose of antipyrine, or c) coadministered pantoprazole and antipyrine according to a randomized three-period change-over design. In the chronic study, another 12 volunteers received 40 mg once-daily oral doses of pantoprazole on day 3 and on days 5-12, and a single oral 5 mg/kg dose of antipyrine on days 1, 12 and 14. Antipyrine plasma concentrations were measured without pantoprazole (day 1), on the last day of chronic dosing with pantoprazole (day 12) and 48 hours after the last dose of pantoprazole (day 14) to differentiate between inhibition and induction, respectively. Both drugs were well tolerated and no adverse events or clinically relevant alterations in vital signs or laboratory parameters were observed during treatment. The point estimates of the respective AUC- and Cmax-ratios for antipyrine with and without pantoprazole were 0.99 and 0.98 in the acute study, and 1.01 and 0.93 on day 12, and 1.04 and 0.99 on day 14 of the chronic study.(ABSTRACT TRUNCATED AT 250 WORDS)

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1994

Dose linearity of the pharmacokinetics of the new H+/K(+)-ATPase inhibitor pantoprazole after single intravenous administration.

Pantoprazole is a specific inhibitor of the H+/K(+)-ATPase of the gastric parietal cell. The dose-dependency of a range of pantoprazole pharmacokinetic characteristics was studied. Twelve healthy male subjects were given 10, 20, 40 and 80 mg pantoprazole intravenously according to a randomized, single blind, 4-period change-over scheme. The area under the concentration vs time curve (AUC) and the maximum serum concentration (Cmax) showed a linear increase in line with the dose. Apparent volume of distribution (Vd area), clearance (Cl) and terminal half-life (t1/2) were independent of the dose. The dose-independent elimination of pantoprazole was attributed to the lack of interaction of the drug with cytochrome P450. In clinical practice, a good predictable response, as well as a low potential for interaction with other drugs might be expected.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1993

Targeted disruption of the trkB neurotrophin receptor gene results in nervous system lesions and neonatal death.

We have generated mice carrying a germline mutation in the tyrosine kinase catalytic domain of the trkB gene. This mutation eliminates expression of gp145trkB, a protein-tyrosine kinase that serves as the signaling receptor for two members of the nerve growth factor family of neurotrophins, brain-derived neurotrophic factor and neurotrophin-4. Mice homozygous for this mutation, trkBTK(-/-), develop to birth. However, these animals do not display feeding activity, and most die by P1. Neuroanatomical examination of trkBTK (-/-) mice revealed neuronal deficiencies in the central (facial motor nucleus and spinal cord) and peripheral (trigeminal and dorsal root ganglia) nervous systems. These findings illustrate the role of the gp145trkB protein-tyrosine kinase receptor in the ontogeny of the mammalian nervous system.

Animals↗
PubMed1993

Characterization of a class Ib gene of the rat major histocompatibility complex.

The cDNA and a partial genomic sequence of a rat class I major histocompatibility (RT1) gene, 11/3R, is reported here. The sequence contains several unique amino acid residues at certain positions, mutations in exon 7 (which is not expressed), a mutation of the canonical exon 8 stop codon to a sense codon, and includes a long 3' untranslated region (utr). The structure of exon 7 differs from that found in most rat class I genes and resembles exon 7 of most H-2K,D,L,Q genes. Parts of the 3' noncoding region are homologous to the RT1.A-4 and certain H-2 genes. Expression is detectable by northern blot analysis in mitogen-stimulated lymphocytes only, by polymerase chain reaction (PCR) in each tissue tested. After transfection into L cells 11/3R can be shown to be expressible at the cell surface. Probes derived from the 3' noncoding part crosshybridize with a number of restriction fragments which map to the RT1.C region, thus defining a subfamily of RT1.C region genes. Several members of this subfamily are deleted in the lm1 RT1 mutant. The 11/3R gene presents typical features of a class Ib gene. Aspects of evolution and the potential function of the gene are discussed.

Amino Acid Sequence↗