Ropivacaine and bupivacaine for analgesia in labour.
Explore the source record for details and available documents.
Amides↗
Biomedical subjects
A Bader
Publications and source records attributed to A Bader.
[Right ventricular thrombus after pacemaker implantation in a patient with secondary antiphospholipid syndrome].
HISTORY AND ADMISSION FINDINGS: An 85-year-old woman was admitted because of frequent syncopes. She also reported slight weight loss, cough and dyspnoea. Chest auscultation revealed slight stridor and a cardiac arrhythmia, with an irregular ventricular rate between 120 and 140 beats/min. INVESTIGATIONS: She had a thrombocytopenia (96 platelets/nl), and the ECG and long-term monitoring showed a tachyarrhythmia with atrial fibrillation, a bifascicular block (left anterior hemiblock and right bundle branch block), as well typical signs of sick-sinus syndrome with short periods of bradycardic sinus rhythm and pauses of up to 6 s on rhythm change. Echocardiography indicated moderately reduced left ventricular function. Chest radiogram revealed tracheal narrowing by a retrosternal goitre. No evidence of tumour was found on bronchoscopy. DIAGNOSIS, TREATMENT AND COURSE: A VVI pacemaker was implanted. When the platelet count dropped to 30/nl idiopathic thrombocytopenic purpura was suspected, but administration of high doses of corticoids and immunoglobulin was without effect. Another echocardiogram, performed because of chest pain suspicious of pulmonary embolism, revealed a large bowl-shaped right ventricular thrombus with floating parts. Demonstration of anticardiolipin antibodies established the diagnosis of antiphospholipid syndrome (APLS), thought to be secondary to thyroid cancer suspected from the computed tomography. The patient died 2 months later from recurrent pulmonary embolism and progressive liver failure. Autopsy revealed a not previously diagnosed tracheal carcinoma with metastases to the thyroid, as well as haematogenous metastatic foci within the right ventricular thrombus. INTERPRETATION: In case of thrombocytopenia of uncertain aetiology APLS should be included in the differential diagnosis, even in the absence of any early or acute thrombosis. If anticardiolipin antibodies and/or lupus anticoagulant are demonstrated, malignant neoplasm should be considered in addition to autoimmune disease.
Aged↗
Tissue engineering of heart valves--human endothelial cell seeding of detergent acellularized porcine valves.
OBJECTIVE: Tissue engineering of heart valves represents a new experimental concept to improve current modes of therapy in valvular heart disease. Drawbacks of glutaraldehyde fixed tissue valves or mechanical valves include the short durability or the need for life-long anticoagulation, respectively. Both have in common the inability to grow, which makes valvular heart disease especially problematic in children. The aim of this study was to develop a new methodology for a tissue engineered heart valve combining human cells and a xenogenic acellularized matrix. METHODS: Porcine aortic valves were acellularized by deterging cell extraction using Triton without tanning. Endothelial cells were isolated in parallel from human saphenous veins and expanded in vitro. Specimens of the surface of the acellular matrix were seeded with endothelial cells. Analysis of acellularity was performed by light microscopy and scanning electron microscopy. Cell viability following seeding was assayed by fluorescence staining of viable cells. RESULTS: The acellularization procedure resulted in an almost complete removal of the original cells while the 3D matrix was loosened at interfibrillar zones. However the 3D arrangement of the matrix fibers was grossly maintained. The porcine matrix could be seeded with in vitro expanded human endothelial cells and was maintained in culture for up to 3 days to document the formation of confluent cultures. CONCLUSIONS: Porcine aortic valves can be almost completely acellularized by a non-tanning detergent extraction procedure. The xenogenic matrix was reseeded with human endothelial cells. This approach may eventually lead to the engineering of tissue heart valves repopulated with the patients own autologous cells.
Animals↗
Development of a small-scale bioreactor for drug metabolism studies maintaining hepatospecific functions.
1. The aim of the study was the development of a small-scale liver cell bioreactor maintaining tissue monoxygenase activity and hepatospecific activities over at least 2 weeks. 2. For characterization the antihypertensive drug urapidil was used as a model compound to study maintenance of metabolic activity. Tissue-specific parameters assessed included urea and albumin secretion as well as cellular integrity. The problem of the use of serum in bioreactor cultures is addressed. 3. Bioreactor runs could be performed in serum- and lactate-free cultures with a joint recovery of oxidative biotransformation capacity for urapidil as well as tissue-specific markers. LDH release was reduced with older cultures. Fibronectin was shown as a contributing factor for cell attachment. 4. In the present study the design and function of a modular, small-scale-type bioartificial liver cell culture model is thus described lending itself for drug metabolism studies but maintaining also typical hepatospecific properties.
Albumins↗
Catalytic activities, protein- and mRNA-expression of cytochrome P450 isoenzymes in intestinal cell lines.
1. Certain chemicals and drugs in addition to metabolically activated carcinogens are substrates for intestinal cytochrome P450s (CYPs) and a number of cell lines are available which could be used in metabolism studies. These include the rat duodenal cell line IEC 6, rat ileal IEC 18, foetal human HuTu 80, foetal human small intestinal FHS 74, human duodenal HCT 8 and human colon CaCo-2 cells, but they lack thorough biochemical characterization. 2. The aim of the present study was therefore to investigate the mRNA and protein expression of CYP1A1, CYP1A2, CYP2C9/10, CYP2E1 and CYP3A. In addition, the metabolism of the immunosuppressant drug tacrolimus and of the procarcinogen 7,12-dimethyl-benz[a]anthracene (DMBA) was studied to obtain information on the functional activity on these cell lines. 3. Of all the cell lines tested only CaCo-2 cells expressed CYP1A1 at the protein and mRNA level, but the CYP2E1 and CYP3A protein was also detected in CaCo-2 and FHS 74 cells. It is of considerable interest that none of the other cell lines expressed CYP1A1, CYP1A2, CYP2C9/10 or CYP3A4 at the protein and mRNA level. 4. When the metabolism of DMBA (a model carcinogen) was studied, CaCo-2 cells produced the following metabolites: 7,12-dihydroxymethylbenz[a]anthracene, 7,12-dimethylbenz-[a]anthracene-di-hydrodiol, 7-methyl-12-hydroxymethylbenz[a]anthracene, 7-hydroxy-methyl-12-benz[a]anthracene and possibly the dihydrated product of the latter two derivatives. 5. CaCo-2 cells also catalysed the metabolism of the immunosuppressant drug tacrolimus resulting in the formation of 13-O-demethyl-tacrolimus bisdemethyl-hydroxy-tacrolimus and demethyl-dihydroxy-tacrolimus. Neither the foetal human small intestinal FHS 74 cell line nor any of the other cell lines were able to catalyse the biotransformation of tacrolimus. 6. In conclusion, only CaCo-2 cells were able to produce metabolites similar to those observed in in vivo metabolism studies, whereas all other cell lines were metabolically incompetent. Therefore, this cell line may be used in studies of intestinal biotransformation.
9,10-Dimethyl-1,2-benzanthracene↗
Investigation of the potential interaction between terfenadine and tedisamil in human liver microsomes.
1. The potential drug-drug interaction of terfenadine and tedisamil has been investigated. Terfenadine is a widely used antihistamine drug with the potential for QTC prolongation. Tedisamil is a potassium channel blocking agent known to produce bradycardia and prolong the effective refractory period in man. 2. Tedisamil and terfenadine were incubated with human liver microsomes for 30 min at 37 degrees C. No significant inhibition of terfenadine biotransformation was seen with 0.1 or 10 microM tedisamil as the formation of the terfenadine alcohol and acid metabolites were unaffected. 3. Based on the in vitro results it is suggested that tedisamil will not interact pharmacokinetically with terfenadine as it does not impair metabolism of terfenadine.
Adult↗
In vitro activities of benzimidazoles against Echinococcus multilocularis metacestodes.
Alveolar echinococcosis, caused by the larval (metacestode) stage of the tapeworm Echinococcus multilocularis, is a lethal parasitosis of the liver prevalent in the Northern Hemisphere. For chemotherapy the benzimidazole derivatives mebendazole and albendazole were introduced, and their use has resulted in a significant improvement in the survival rates. However, data from experiments with animals and clinical observations indicate that these drugs elicit only parasitostatic activity and in most cases are not able to completely eliminate the parasitic metacestode tissue. In the present study, we applied a culture system for the in vitro growth and proliferation of E. multilocularis metacestodes to analyze the parasitostatic and parasitocidal potential of mebendazole. Here, we demonstrate for the first time that at concentrations of >0.1 microM, i.e., at concentrations used for therapy of human alveolar echinococcosis, this antihelminth drug is parasitocidal in vitro. Viability assessment was performed by infection experiments with Meriones unguiculatus and mebendazole-treated metacestode tissue and by reverse transcription-PCR for the detection of E. multilocularis mRNA. The E. multilocularis in vitro model proved to be a valuable tool for the analysis of the potential of antihelminth drugs.
Animals↗
[A new concept for substitutes in vascular surgery].
In a tissue engineering approach to develop vascular grafts without disadvantages such as early thrombosis, neointimal hyperplasia, the inability to grow, aneurysm formation, as well as life-long anticoagulation, decellularized matrix tubes which were obtained by enzymatic cell extraction from a porcine aorta were seeded with human endothelial cells in vitro. This procedure led to completely biological vascular grafts with good handling qualities and sufficient burst strength, presumably suitable for implantation in the arterial circuit.
Animals↗
Drug metabolism in hepatocyte sandwich cultures of rats and humans.
Adult hepatocytes from rat and man were maintained for 2 weeks between two gel layers in a sandwich configuration to study the influence of this culture technique on the preservation of basal activities of xenobiotic-metabolizing phase I and phase II enzymes. The response of these enzyme activities to an enzyme inducer was investigated using rifampicin (RIF). Basal levels of cytochrome P-450 (CYP) isozymes were characterized by measuring ethoxyresorufin O-deethylation (EROD), ethoxycoumarin O-deethylation (ECOD), and the specific oxidation of testosterone (T). In hepatocytes from untreated rats, CYP isozyme levels, including the major form CYP 2C11, increased during the first 3 days in culture. After this period of recovery, the levels of CYP 2C11, CYP 2A1, and CYP 2B1 decreased, whereas CYP 3A1 increased. In contrast to these dynamic changes, CYP activities such as CYP 1A2 and the major isozyme CYP 3A4 were largely preserved until day 9 in cultures of human hepatocytes. In measuring phase II activities, a distinct increase in glucuronosyltransferase (UDP-GT) activity toward p-nitrophenol (PNP) was found for rat and human hepatocytes over 2 weeks in culture. Sulfotransferase (ST) activity toward PNP showed an initial increase, with a maximum at day 7 and day 9 in culture, respectively, and then decreased until day 14. Glutathione S-transferase (GST) activity decreased constantly during the time of culture. Effects of the enzyme-inducing drug rifampicin on phase I and phase II enzymes were investigated using cultured human hepatocytes. Rifampicin treatment (50 micromol/L) for 7 days resulted in a 3.7-fold induction of CYP 3A4 at day 9 in culture. ECOD activity was increased sixfold and phase II ST activity increased twofold compared to the initial value at day 3. No effect of rifampicin on CYP 3A was found in cultures of rat hepatocytes. These results demonstrate that rat and human hepatocytes preserve the major forms of CYP isozymes and phase II activities and respond to inducing drugs such as rifampicin. The novel hepatocyte sandwich culture is suitable for investigating drug metabolism, drug-drug interactions and enzyme induction.
Adult↗
Interleukin-6 is necessary, but not sufficient, for induction of the humanC-reactive protein gene in vivo.
We have investigated the involvement of interleukin-6 (IL-6) in the induction of the gene encoding the acute-phase protein human C-reactive protein (hCRP). In transgenic mice the hCRP gene can be induced by lipopolysaccharide (LPS), but not by IL-6. In contrast, hCRP was inducible by IL-6 in primary human hepatocytes and in primary hepatocytes isolated from transgenic mice. To further evaluate the role of IL-6, we introduced the hCRP transgene into animals lacking endogenous IL-6 (IL-6-negative mice). Here, hCRP was not inducible by LPS, but was induced by a combination of LPS and IL-6. These results clearly demonstrate that IL-6 is necessary, but not sufficient, for the induction of hCRP expression. These animal models will allow further dissection of the cytokine network responsible for the regulation of the major human acute-phase reactant CRP.
Animals↗
Isolation of the putP gene of Corynebacterium glutamicum and characterization of a low-affinity uptake system for compatible solutes.
Corynebacterium glutamicum accumulates the compatible solutes proline, glycine betaine, and ectoine under conditions of high osmolality. Uptake of proline is mediated by both a high-affinity and a low-affinity secondary transport system. The low-affinity uptake system also accepts glycine betaine and ectoine as substrates. In the present study, the gene encoding the high-affinity proline uptake system PutP was isolated by heterologous complementation of Escherichia coli mutant strain WG389, which lacks the transport systems BetT, PutP, ProP, and ProU and is unable to synthesize proline and glycine betaine. This gene (putP) encodes a protein of 524 amino acids that shares identity with the proline transport systems PutP of E. coli, Staphylococcus aureus, Salmonella typhimurium, Haemophilus influenzae, and Klebsiella pneumoniae. Functional studies of PutP synthesized in E. coli mutant strain MKH13, which also lacks the transport systems for compatible solutes and is unable to synthesize glycine betaine, revealed that this carrier system is not regulated by the external osmolality on the level of activity. Km values of 7.6 mM for proline and 1.3 mM for sodium as cotransported ion were determined. Deletion of the putP gene allowed the functional characterization of another proline uptake system with low affinity.
Amino Acid Sequence↗
Application of a stable cell culture assay for the functional assessment of novel MR contrast agents.
The purpose of this study was to apply a new cell culture assay that preserves hepatocyte orientation and differentiation for screening of MR contrast agents with hepatocyte specificity. Cultured hepatocytes were sandwiched between two layers of collagen, preserving both hepatocyte function and morphology over a prolonged period of time. Plain and rhodaminated monocrystalline iron-oxide particles (MION and MION-rh) and asialoglycoprotein receptor-specific rhodaminated asialofetuin coupled to MION (MION-ASF-rh) were prepared. Dose-dependent competition experiments of these agents were performed with D(+)-galactose to determine the specificity of galactose-mediated cell uptake. To assess the impact of cell integrity on cell uptake dose-dependent functional experiments with two hepatotoxins (ethanol and CCl4) were performed. Normal cell cultures showed significantly higher fluorescent-light emission after incubation with hepatocyte-directed ASF-MION-rh than after incubation with MION-rh. Competition experiments of ASF-MION with galactose showed a dose-dependent decrease in calibrated fluorescent-light emission. Cell cultures treated with hepatotoxins demonstrated a dose-dependent reduction in calibrated fluorescent-light emission following incubation with ASF-MION-rh. The validated assay system allows assessment not only of hepatocyte specificity, but also of hepatocyte damage. Because the assay can be applied to cells from any species (rat, pig, human), it may represent an ideal test system prior to clinical trials of new hepatocyte-directed MR contrast agents.
Animals↗
Isolation of monoclonal antibodies from cell containing hybridoma broth using a protein A coated adsorbent in expanded beds.
A novel expanded bed adsorbent carrying a recombinant protein A ligand was used for the isolation of monoclonal antibodies from cell containing hybridoma fermentation broth. The untreated effluent from a continuous hybridoma cultivation was applied to the stable expanded adsorbent (Streamline rProteinA), which proved to have a high capacity for the MAb studied (14 mg MAb per ml of adsorbent). A clarified and highly concentrated (up to 50 fold) eluate of high purity was obtained. A scale up of the MAb purification is demonstrated from lab scale (250 mg MAb per purification cycle) to a small pilot scale (2 g MAb per cycle). Low product concentration in the broth in combination with the high capacity of the adsorbent caused long sample application cycles (10-11 h). Experimental problems arising from these long cycle times are discussed with regard to a large scale application of the method.
Antibodies, Monoclonal↗
3-D coculture of hepatic sinusoidal cells with primary hepatocytes-design of an organotypical model.
Models for cocultures of parenchymal (PC) and nonparenchymal cells (NPC) of the liver relied on mixing the cells in a two-dimensional configuration or on establishing spheroidal aggregates. In vivo hepatic nonparenchymal cells, such as endothelial cells and Kupffer cells, are separated from parenchymal cells by extracellular matrix (ECM). Due to their location outside of the space of Disse they can form a barrier toward the sinusoid. Hepatocytes are attached to ECM of the space of Disse via two opposing sinusoidal surfaces. No three-dimensional coculture model reflecting this specific microenvironment of the liver cell plates in vivo has been available to date. We designed a three-dimensional model by positioning NPC on top of PC enclosed as a monolayer within a collagen sandwich. A gas-permeable membrane support can be used to allow the supply of oxygen to the resulting cell plate also from underneath the cell layers. Morphological analysis was performed by inverse and cross-sectional studies by light microscopy, scanning, and transmission electron microscopy of the coculture model. Cuboidal hepatocytes formed confluent layers below the NPC layer. They regularly expressed bile canaliculi at intercellular contact zones. Both sinusoidal surfaces expressed microprojections. Characteristic NPC including endothelial cells, Kupffer cells, and Ito cells completely covered the second matrix layer within a week. Kupffer cells were located on top of endothelial cells. Ito cells were intermingled and could be identified by their intracytoplasmic lipid droplets. LPS stimulation of cocultures resulted in a depression of albumin secretion. Phase I and phase II metabolites of the cytochrome P-450 1A1 substrate ethoxyresorufin were generated independently from the presence of cocultured NPC. This study describes the development of a novel three-dimensional coculture model, which intends to mimic more closely the microenvironment of the hepatic sinusoid by respecting the specific plate structure of the liver parenchyma. The model could serve as a complex tool to study potential collaborations between PC and NPC of the liver.
Albumins↗
Tacrolimus (FK 506) biotransformation in primary rat hepatocytes depends on extracellular matrix geometry.
Established in vitro models for studies of hepatic drug biotransformation include the use of primary hepatocytes. In normal liver the space of Disse provides the possibility of bilateral attachment to extracellular matrix for each hepatocyte. This configuration is disrupted by the cell isolation procedure of normal liver tissue, which delivers suspensions of round shaped cells. In standard culture configurations this unphysiologic cell shape terminates in a morphological dedifferentiation and inability to biotransform drugs. This study analyses the relevance of extracellular matrix geometry in hepatocyte monolayer configurations for expression and activity of cytochrome P450 3A. This enzyme is involved in the biotransformation of a large number of pharmaceuticals including the immunosuppressants tacrolimus and sirolimus. Morphological analysis of primary rat hepatocytes cultured with and without overlay of collagen type I was performed by transmission and scanning electron microscopy. Expression and activity of cytochrome P450 3A was studied by Western blot and the use of two model drugs specific for this enzyme. To this purpose the immunosuppressive drugs tacrolimus and sirolimus were used. Metabolites were analyzed by HPLC and HPLC/MS. Two sided attachment to extracellular matrix induces profound changes of the hepatocellular morphology in vitro resulting in the reconstitution of a polyhedric cell shape. This phenomenon is paralleled by an enhanced expression of cytochrome P450 3A and corresponding metabolic activity. As shown for tacrolimus biotransformation, the model may be useful to study complex metabolic patterns. In addition this model may facilitate studies of the kinetics of hepatocellular drug biotransformation in a setting with prolonged stability.
Albumins↗
Identification of drugs inhibiting the in vitro metabolism of tacrolimus by human liver microsomes.
1. Tacrolimus, an immunosuppressive macrolide, is metabolized by enzymes of the cytochrome P450 3A subfamily. In this study, 34 drugs were tested for their interactions with tacrolimus metabolism by human liver microsomes. 2. Fifteen drugs which inhibit the in vitro metabolism of tacrolimus were identified: bromocriptine, corticosterone, dexamethasone, ergotamine, erythromycin, ethinyloestradiol, josamycin, ketoconazole, miconazole, midazolam, nifedipine, omeprazole, tamoxifen, troleandomycin and verapamil.
Bromocriptine↗
Metabolism of the macrolide immunosuppressant, tacrolimus, by the pig gut mucosa in the Ussing chamber.
1. The macrolide tacrolimus (FK506), used as an immunosuppressant, is a cytochrome P450 (CYP) 3A substrate in the liver. The metabolism of tacrolimus and the transport of its metabolites in the pig gut was studied in the Ussing chamber. Tacrolimus and its metabolites were quantified by h.p.l.c./mass spectrometry. 2. In the Ussing chamber, demethyl, didemethyl, hydroxy and hydroxy-demethyl tacrolimus were generated. Their formation was concentration- and time-dependent. The metabolite pattern was not different from that after incubation of tacrolimus with human small intestinal microsomes. 3. The metabolite formation was highest in the duodenum and declined in the order duodenum > jejunum > ileum > colon > stomach. 4. Since tacrolimus metabolism was inhibited by the specific CYP3A inhibitors, troleandomycin and ketoconazole, we concluded that these enzymes are involved in intestinal metabolism of tacrolimus. 5. Tacrolimus metabolites re-entered the mucosa chamber (> 90%) and passed through the small intestinal preparation into the serosa chamber. 6. It is concluded that tacrolimus is metabolized in the intestine, that the metabolites are able to re-enter the gut lumen and also enter into the portal vein and that small intestinal metabolism and transport is at least in part responsible for the low oral bioavailability of tacrolimus.
Animals↗
Hepatic tissue culture model for study of host-parasite interactions in alveolar echinococcosis.
An in vitro model for growth and differentiation of the metacestode tissue of the tapeworm Echinococcus multilocularis is described. This model simulates the organotropism of the parasite toward the liver of the intermediate host. In the presence of collagen-embedded primary hepatocytes from rats and humans, which can be kept in culture for 2 to 3 months, the parasitic vesicles grew by exogenous budding and multiplied about 12-fold within 3 weeks. In contrast, without the hepatocytes, the metacestodes rapidly degenerated. Development of protoscolices was seen only in the presence of rat hepatocytes but not in coculture of the metacestodes with hepatocytes of human origin, thus reflecting the in vivo situation during infection of rodents and in alveolar echinococcosis in humans. The experiments indicated that growth of the metacestodes and development of protoscolices depended on soluble low-molecular-weight factors released by the hepatocytes. The in vitro-grown metacestodes did not differ morphologically from the larvae found in infected intermediate hosts, and their infectivity was completely maintained. This report describes the first in vitro model of alveolar echinococcosis and will be the basis for future studies on host-parasite interactions of this important zoonosis.
Animals↗