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  • Life and Medical Sciences  (5,983)
  • Engineering General  (1,230)
  • pharmacokinetics  (814)
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 26 (1990), S. 222-226 
    ISSN: 1040-452X
    Keywords: Cow ; Classification ; Cumulus oocyte complexes ; In vitro maturation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Bovine cumulus oocyte complexes (COCs) were isolated from antral ovarian follicles (4-8 mm). Immature COCs were classified into four categories, based on the homogeneity and clearness of the ooplasm and the transparency and compactness of the cumulus investment. In this study, the incorporation of TCA-precipitable 35S-methionine and the protein synthesis patterns of oocytes of these four categories were examined. Before maturation in vitro, similar incorporation rates and identical protein synthesis patterns were observed between oocytes of categories 1-3. Immature oocytes of category 4 showed reduced incorporation rates and exhibited aberrant protein synthesis patterns. After maturation in vitro, the patterns of category 4 oocytes were identical with the patterns of those in categories 1-3. The incorporation of 35S-methionine into in vitro matured oocytes was lower (P 〈 .001) in all categories.Based on these results, it is concluded that the initial classification of oocytes into four categories can be reduced to two categories.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1040-452X
    Keywords: Cow ; In vitro maturation ; Inhibitors ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Bovine cumulus oocyte complexes were cultured for various periods and either denuded and orcein stained or radiolabeled with 35S-methionine or 32P-orthophosphate. Specific inhibitors were added to the culture medium to investigate mRNA and protein synthesis requirements for both nuclear and cytoplasmic changes during maturation in vitro. Inhibition of mRNA synthesis by α-amanitin during the first 2 h of culture prevented the phosphorylation of some specific proteins preceding GVBD and decreased the occurrence of GVBD from 97% to 27%. In addition, in oocytes that had undergone GVBD, only part of the changes in protein synthesis after GVBD were observed. Addition of α-amanitin after 3 h of culture had no effect on meiotic maturation. When cumulus oocyte complexes were cultured in the presence of cycloheximide, the phosphorylation of specific proteins was also blocked and only 5% of the oocytes underwent GVBD. Addition of cycloheximide after 4, 6, or 8 h of culture resulted in an increasing percentage of GVBD, but the oocytes became arrested in metaphase I. When cycloheximide was added from 12 h of culture onwards, nuclear progression to metaphase II was increasingly restored.It is concluded that after the onset of culture, both mRNA and protein synthesis are necessary for the phosphorylation of specific proteins and for GVBD. Further-more, transcription during the first hours of culture is needed for the synthesis of new proteins after GVBD.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 29 (1991), S. 271-275 
    ISSN: 1040-452X
    Keywords: Cow ; Maturation ; Oocyte ; Protein phosphorylation ; Superovulation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: To investigate protein synthesis and phosphorylation during bovine oocyte maturation in vivo, oocytes were collected at consecutive times after the preovulatory luteinizing hormone (LH) peak. Therefore, heifers treated for superovulation were ovariectomized between 3 and 20 h after the maximum of the LH peak. Subsequently, cumulus-enclosed oocytes, selected from nonatretic follicles 〉10 mm, were radiolabeled with 35S-methionine or 32P-orthophosphate for 3 h and individually prepared for gel electrophoresis. Changes in the protein synthesis patterns were observed coinciding with germinal vesicle breakdown (GVBD). No changes were detected during the ensuing maturation period or coinciding with the extrusion of the first polar body. In addition, the protein phosphorylation patterns exhibited striking differences around GVBD. In particular, a phosphoprotein band of 19 kDa and the two heavily phosphorylated proteins with apparent molecular weights between 50 and 60 kDa were present in patterns of oocytes in the germinal vesicle stage. The results are discussed in relation to previous data obtained during maturation in vitro.
    Additional Material: 1 Tab.
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  • 4
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We studied the effects of parathyroid hormone (PTH) on two markers of the osteoblast phenotype: alkaline phosphatase (AP) (activity and mRNA) and cyclic adenosine monophosphate (cAMP) accumulation. Osteoblast-like cells derived from fetal rat (ROB) and mouse (MOB) calvariae were isolated by collagenase treatment. Cells were cultured in α-Minimal Essential Medium (MEM) with 2% fetal calf serum (FCS) for 4 days. In ROB and MOB bPTH(1-34) induced a fast increase (up to 5 minutes) in cAMP accumulation. When equal amounts of cells were seeded, the cAMP accumulation was higher in MOB than in ROB. No difference in basal AP activity was observed between ROB and MOB. When bPTH(1-34) was added to ROB for the last 24 or 48 hr, AP activity decreased dose dependently. However, MOB treated with bPTH(1-34) for the last 24 or 48 hours showed an increase of AP activity. Basal AP activity was positively correlated with the seeding density of ROB and MOB cultures. Basal AP activity influenced the degree of inhibition (ROB) or stimulation (MOB) after incubation with bPTH(1-34). © 1993 Wiley-Liss, Inc.
    Additional Material: 9 Ill.
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  • 5
    ISSN: 1569-8041
    Keywords: melanoma ; pharmacodynamics ; pharmacokinetics ; temozolomide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: The DNA repair protein O6-alkylguanine-DNA alkyl transferase (AT) mediates resistance to chloroethylnitrosoureas. Agents depleting AT such as DTIC and its new analogue temozolomide (TMZ) can reverse resistance to chloroethylnitrosoureas. We report the results of a dose finding study of TMZ in association with fotemustine. Patients and methods: Twenty-four patients with metastatic melanoma or recurrent glioma were treated with escalating dose of oral or intravenous TMZ ranging from 300 to 700 mg/m2, divided over two days. Fotemustine 100 mg/m2 was given intravenously on day 2, 4 hours after TMZ. AT depletion was measured in peripheral blood mononuclear cells (PBMCs) and in selected cases in melanoma metastases and was compared to TMZ pharmacokinetics. Results: The maximum tolerated dose (MTD) of TMZ was 400 mg/m2 (200 mg/m2/d) when associated with fotemustine the 2nd day with myelosuppression as dose limiting toxicity. The decrease of AT level in PBMCs was progressive and reached 34% of pretreatment values on day 2. There was however wide interindividual variability. AT reduction was neither dose nor route dependent and did not appear to be related to TMZ systemic exposure (AUC). In the same patients, AT depletion in tumour did not correlate with the decrease of AT observed in PBMCs. Conclusions: PBMCs may not be used as a surrogate of tumour for AT depletion. Further study should concentrate on the pharmacokinetic pharmacodynamic relationship in tumour to provide the basis for individually tailored therapy.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-1041
    Keywords: FCE 22101 ; penem antibiotic ; pharmacokinetics ; single dose ; healthy volunteers ; adverse effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The clinical tolerance and pharmacokinetics of FCE 22101 (sodium (5R, 6S)-6-[(1R)-hydroxyethyl]-2-carbamoyloxymethyl-2-penem-3-carboxylate), a new penem antibiotic, have been studied after giving a single i.v. dose of 4 mg·kg−1 to ten healthy male volunteers. The pharmacokinetics was estimated according to a two-compartment open model. The peak plasma concentration (Cmax) was 15.5 (1.08) µg·ml−1, mean (SEM). FCE 22101 was rapidly cleared from the systemic circulation [ $$t_{1/2\lambda _z } $$ =44.2 (4.2) min; CL=7.21 (0.47) ml·kg−1·min−1]. The mean apparent volume of distribution at steady-state was 246 (16.9) ml·kg−1. The mean residence time relative to the 10 min infusion was 39.4 (1.5)min. Urinary recovery of FCE 22101 showed wide inter-subject variation, ranging from 10.2 to 53.6% of the dose. No subject complained of adverse effects.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-1041
    Keywords: Tolbutamide ; diabetes mellitus ; non-insulin dependent ; pharmacokinetics ; pharmacodynamics ; glucose ; insulin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary It is uncertain how the hypoglycaemic effect of sulphonylureas varies with drug concentration in patients with non-insulin-dependent diabetes mellitus. The interrelationship of tolbutamide dosage and concentration, and glucose and insulin concentrations were therefore examined in 54 out-patients (the observational group) and in 20 patients studied under controlled conditions (the experimental group). In the observational group, tolbutamide concentration depended significantly on the daily dose, time from dose to sampling, body weight, and age. Blood glucose and insulin concentration were related, but were independent of tolbutamide concentration. In the experimental group, peak, but not pre-dose, tolbutamide concentration, depended on dose and on body mass index. Fasting and maximum post-prandial blood glucose concentration were positively correlated with maximum tolbutamide concentration, probably because tolbutamide dosage was highest in those with the poorest response. In the subset with a fasting blood glucose concentration of less than 8 mmol·l−1, neither glucose nor insulin concentrations depended significantly on tolbutamide concentrations. Tolbutamide concentration does not directly determine hypoglycaemic response in outpatients, and therapeutic monitoring of drug concentrations would not improve the management of such patients.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 23 (1982), S. 331-333 
    ISSN: 1432-1041
    Keywords: ketoconazole ; vaginal candidosis ; oral antimycotic ; distribution ; pharmacokinetics ; vaginal tissue concentrations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Plasma samples and biopsies of vaginal tissue were obtained from 23 healthy women undergoing operative sterilization, 1 to 6 h after a single oral dose of ketoconazole 200 mg. Drug concentrations in plasma and tissue, were measured by a specific gas chromatographic method. The vaginal tissue concentration averaged 2.4 times less than the corresponding plasma levels. Equilibrium between tissue, and plasma was established within 1 h after dosing, when vaginal tissue levels exceeded 1 µg/g. Ketoconazole concentrations decayed monoexponentially over the time interval studied (1–6 h), with the similar half-lives of 1.2 and 1.4 h in plasma and tissue, respectively. Following an oral 200 mg dose, a tissue concentration not less than 0.01 µg/ml was maintained over a 12 h period. This concentration has been shown to prevent outgrowth of the invasive (pseudo) mycelial form ofCandida albicans. Hence, a b.i.d. or t.i.d. dosage schedule of ketoconazole in vaginal candidosis would give continuously effective levels at the site of infection. Ketoconazole concentrations in vaginal fluid are thought to be much higher than in the tissue because of ion-trapping. The present data may explain the efficacy of oral ketoconazole in the treatment of vaginal candidosis.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-1041
    Keywords: methotrexate ; hydroxymethotrexate ; lymphoid malignancy ; renal excretion ; metabolism ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In children with lymphoid malignancies 18 courses of methotrexate (18–200 mg/kg) administered as a 24-h infusion were monitored. Plasma concentrations and renal excretion rates of methotrexate (MTX) and 7-hydroxymethotrexate (7-OHMTX) were determined. A low correlation was found between the administered dose of MTX and the body exposure to MTX or 7-OHMTX. Although 84% of the MTX eventually recovered from the urine was excreted during the 24 h of the infusion, the renal clearance of MTX was markedly lower during the time of the infusion than after it. There were courses with a low and others with a high renal clearance of MTX during the infusion, despite the same urine flow. A low MTX renal clearance was correlated with a high body exposure to MTX. As the same variations were also seen in the same patient during successive courses, pharmacokinetical characterization of patients appears questionable. The renal clearance of 7-OHMTX was significantly lower than the renal clearance of MTX, and the body exposure to 7-OHMTX ranged from 2–40% of the MTX body exposure. Treatment courses with a low or a high body exposure to 7-OHMTX were not associated with different urinary recoveries of the metabolite. Differences in MTX hydroxylation could not be substantiated. Because the concentration of 7-OHMTX is high soon after the end of an infusion, a specific method of MTX determination should be chosen for controlling treatment.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1569-8041
    Keywords: carboplatin ; cisplatin ; intrapleural combination ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: Cisplatin (DDP) and carboplatin (CBDCA) are two of the mosteffective drugs in a locoregional approach. Since simultaneous combinedtreatment with intrapleural DDP and CBDCA has not been reported in humans, weinvestigated its use in patients with malignant effusions, focusing onpharmacokinetics. Patients and methods: The pharmacokinetics of DDP and CBDCA were studiedin 10 patients with malignant pleural effusion treated intrapleurally with acombination of DDP (60 mg/m2) and CBDCA (270mg/m2) and in additional patients who received the same dosesof drugs administered intravenously as single agents or in combination.Platinum (Pt) species originating from DDP (metabolites plus unchanged DDP)and intact CBDCA in plasma and pleural fluid ultrafiltrates were measured bymeans of high performance liquid chromatography and atomic absorptionspectrometry. Results: Both in the plasma and pleural fluid, the total levels of free Ptrepresented the additive result of the individual concentrations of CBDCA andPt-species derived from DDP. After intrapleural combination, highpleural-plasma ratios of the peak concentrations and AUCs were observed bothfor CBDCA and DDP-derived Pt species, highlighting a distinct localpharmacological advantage. However, the Pt species originating from DDP wereabsorbed more rapidly from the pleural cavity than CBDCA (Ka= 86 × 10-3 vs. 37 ×10-3 min-1, P 〈 0.05).Intrapleural combination of CBDCA and DDP produced therapeutic plasma levelsof reactive (free) DDP species and increased the extent of their residencetime (MRT) compared with single intravenous DDP treatment [peak concentration:1.1 ± 0.1 (SD) vs. 1.6 ± 0.2 µg/ml; MRT: 5.2 ± 1.9vs. 0.5 ± 0.06 h]. Furthermore, the plasma AUC of free CBDCA afterintrapleural combined treatment (2.1 ± 0.5 mg/ml × min) wassimilar to that after intravenous administration of CBDCA alone (2.1 ±0.2 mg/ml × min). The intrapleural treatment was well tolerated by allpatients. Toxicity consisted of mild nausea and vomiting (grade 1–2according to the WHO scale) in four patients. Myelosuppression (grade1–2) was remarkable only in two heavily pretreated patients. No evidenceof recurrence of the pleural effusion was observed in six patients (completeresponse), while an asymptomatic minimal fluid reaccumulation not requiringdrainage (partial response) was observed in four patients. Conclusions: The pharmacologic results seem to exclude a pharmacokineticinteraction between CBDCA and DDP and suggest that a dose of CBDCA 2-foldhigher than that used in this study associated intrapleurally with 60mg/m2 DDP could induce an acceptable and predictablemyelosuppresion.
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