Search PubMed⌕ Search

Biomedical subjects

A Adam

Publications and source records attributed to A Adam.

At least 109 records · Page 6Linked to original sources
PubMed1996

Effects of captopril and Icatibant on bradykinin (BK) and des [Arg9] BK in carrageenan-induced edema.

The effects of captopril, an angiotensin-converting enzyme inhibitor (ACEI), and a selective B2 kinin receptor antagonist (Icatibant) were examined on the paw edema and tissue contents of bradykinin (BK) and des[Arg9]BK following the intraplantar injection of carrageenan in rats. To this end, BK-like immunoreactivity (BK-LI) and des[Arg9]BK-LI were measured with highly sensitive and specific chemiluminescent enzyme immunoassays. Because pentobarbital significantly reduced the carrageenan-induced edema between 3 and 8 h, experiments were conducted in conscious rats. Icatibant (32.5 nmol/paw; intraplantar) significantly reduced carrageenan-induced paw edema between 3 and 8 h in captopril-untreated rats and at 1 and 3 h in captopril-treated rats (0.2 mg/kg x 5 days, per os). The paw content of BK-LI was increased 10-fold in captopril-untreated and 29-fold in captopril-treated rats 1 h after carrageenan injection. In parallel, des[Arg9]BK-LI was increased 8-fold in captopril-untreated and 24-fold in captopril-treated rats. Icatibant prevented the maximal increases in BK-LI and des[Arg9]BK-LI induced by carrageenan. It is concluded that inhibition of ACE by captopril enhanced the early production of endogenous BK and the edema formation induced by carrageenan through a B2 receptor-mediated mechanism. However, the B2 receptor does not appear to be involved in the late phase of the inflammatory response (from 5 to 24 h) to carrageenan in rats pretreated with ACEI. Although the concentrations of des[Arg9]BK were greater than those of BK, it is unlikely that B1 receptors play a significant role in this model of carrageenan-induced edema.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1996

Labelling of haptenic drug with digoxigenin for competitive immunoassay: its application to lesopitron, a new anxiolytic agent.

A new labelling approach of haptenic drugs with digoxigenin for the development of competitive enzyme immunoassay (EIA) is reported. It consists of the covalent linking of the hapten to the preactivated digoxigenin derivative and revealing the immune complexes with anti-digoxigenin Fab fragments coupled to alkaline phosphatase. This approach has been applied to the development of an EIA for the pharmacokinetic study of lesopitron (E-4424), a new anxiolytic agent. The assay involves a solid-phase immobilization of IgG purified from polyclonal antiserum developed against the butylamino derivative of lesopitron covalently linked to bovine serum albumin. The tracer consists of the covalent linking of the same butylamino derivative to digoxigenin-3-O-methylcarbonyl-epsilon-aminocaproic acid N-hydroxysuccinimide ester. The calibration curve for E-4424 from 12.5 to 6400 pg per well displays an ED50 of 34.5 pg per well, a slope factor of 0.86 and a minimum detectable dose of 4.1 pg per well. The accuracy and the precision of the assay assessed at three different concentrations of E-4424 (500, 1000 and 2000 pg ml-1) give a recovery higher than 95% and intra- and inter-assay RSDs lower than 5 and 10%, respectively. The specificity of the assay was demonstrated by a good correlation of the samples analysed by both HPLC and EIA. A kinetic profile of E-4424 in rats following an oral dose of 50 mg kg-1 has also been established.

Animals↗
PubMed1996

External beam and intraluminal radiotherapy for locally advanced bile duct cancer: role and tolerability.

BACKGROUND AND PURPOSE: Cholangiocarcinoma is rare but carries a poor prognosis. Radiotherapy has been used either as an adjuvant treatment following surgical resection of tumour or for palliation. The purpose of this study was to assess the feasibility and morbidity of accelerated external beam radiotherapy with or without intraluminal radiotherapy in the treatment of locally advanced bile duct cancer. MATERIALS AND METHODS: Thirty eight patients were treated. Surgical procedures performed prior to radiotherapy were extended hepatectomy (3), hepaticojejunostomy with tumour resection (6), palliative biliary-enteric bypass (6), biopsy (4), Whipple's procedure (1), gastrojejunostomy (1) and cholecystectomy (1). Twenty patients received external beam radiotherapy (ERT). Six patients received one Phase of ERT and 12 received two Phases, separated by a 2-week gap. Dose per Phase was 22.5 Gy in 10 twice daily fractions. After 1989, dose per Phase was increased to 27.5 Gy. One patient received Phase I ERT (30.0 Gy) using conventional fractionation and one patient received an uninterrupted, conventionally fractionate course of treatment (50.0 Gy). Fourteen patients received both ERT and intraluminal radiotherapy (IRT) using iridium-192 (192Ir) wire passed through a percutaneous, transhepatic catheter (median dose, ERT 23.8 Gy + IRT 40.0 Gy). In addition, four patients received IRT alone (median dose 45.0 Gy at 1 cm radius). Patients were followed for at least 42 months. RESULTS: Median overall survival was 15 months. Overall survival for the whole group at 1,2 and 3 years was 59.6%, 32.5% and 16.2%. Thirty four patients died of disease. Radiotherapy caused acute toxicity in seven patients. According to RTOG/EORTC criteria toxicity was Grade 1 in four cases, Grade 2 in two cases and Grade 3 in one case. Two patients developed gastrointestinal bleeding as a late complication of radiotherapy. CONCLUSIONS: Accelerated external beam radiotherapy with or without intraluminal radiotherapy is feasible and associated with acceptable toxicity when used in the management of advance cholangiocarcinoma.

Bile Duct Neoplasms↗
PubMed1996

A role for B1 and B2 kinin receptors in the modulation of T-kininogen during the acute phase response of inflammation.

Kinin antagonists at B1 and B2 receptors were examined on liver and serum concentrations of immunoreactive T-kininogen and its gene expression in a rat model of carrageenan-induced hindpaw edema. Whereas the B2 antagonist, HOE140, dose-dependently inhibited the paw edema induced by intraplantar injection of carrageenan, the B1 receptor agonist [Sar(D-Phe8)des-Arg9]BK and antagonist [Lys(Leu8)des-Arg9]BK were ineffective. On its own, HOE140 (3.25 x 10(-7) mol/ paw, intraplantar) had no effect on liver and serum T-kininogen levels but it significantly enhanced liver T-kininogen concentrations in rats pretreated with carrageenan at 8 and 24 h postinjection. In the liver, the most pronounced effect was seen at 24 h (treated 248 +/- 7 micrograms/g vs. untreated 113 +/- 9 micrograms/g). The same dose of HOE140 increased serum T-kininogen from 1255 +/- 57 to 1696 +/- 83 micrograms/ml at 24 h. HOE140 did not affect tissue albumin content during the same period. Transcript measurements revealed that the steady-state level of liver T2-kininogen mRNA was specifically increased by HOE140 during inflammation. In carrageenan-treated rats, the B1 antagonist [Lys(Leu8)des-Arg9]BK also significantly increased liver T-kininogen at 24 h. The present results support a role for B2 kinin receptors in the early phase of acute phase protein synthesis and of both B2 and B1 receptors in the late phase (24 h). Hence, systemic effects of kinins should be taken into account in the pharmacology and physiopathology of B1 and B2 kinin receptors in inflammation.

Acute-Phase Reaction↗
PubMed1996

Bradykinin decreases T-kininogen synthesis in a rat hepatoma cell line: evidence of bradykinin B2-type receptors.

Using the rat H4-II-E-C3 hepatoma cell line, we investigated the presence of [125I][Tyr8]BK binding sites and the direct modulation of T-kininogen synthesis, an acute phase protein of inflammation, by bradykinin (BK) analogues. H4-II-E-C3 membrane preparations exhibited [125I][Tyr8]BK binding sites with a Kd of 4 nM and a Bmax of 120 fmol/mg of protein. Des-Arg9-BK showed no affinity (Ki > 10(-4) M) for these sites. The B2 metabolism-resistant and selective agonist [Phe8 psi (CH2-NH)Arg9]BK decreased the T-kininogen concentration in H4-II-E-C3 medium by 23% (p < 0.05). This effect was reversed by coincubation with the B2 antagonist HOE140. The B1 agonist Sar[D-Phe8]des-Arg9-BK and the B1 antagonist Lys[Leu8]des-Arg9-BK did not modify T-kininogen concentrations. The interaction between cytokines and kinins in the modulation of T-kininogen synthesis was also studied. Preincubation of hepatoma cells for 1 h with interleukin-1 alpha (IL-1 alpha) alone reduced T-kininogen concentrations by 37%, and this effect was blocked by co-addition of HOE140. Preincubation with interleukin-6 (IL-6) increased T-kininogen levels by threefold. Coincubation in the presence of the B2 agonist decreased this augmentation by 24%. The latter effect was reversed by co-addition of HOE140. None of the cytokines tested induced a response to the B1 agonist or antagonist under the experimental conditions studied. Overall, these results support the presence of a functional B2 receptor on H4-II-E-C3 cells that modulates T-kininogen synthesis. We suggest that the receptor is involved in vivo in a retroaction loop between kinins and T-kininogen production during inflammation. We speculate that BK could be a mediator in the modulation of acute phase protein synthesis by the cytokines IL-1 alpha and IL-6.

Acute-Phase Reaction↗
PubMed1996

Endovascular repair of residual iliac artery aneurysms following surgery for ruptured abdominal aortic aneurysm.

Emergency repair of ruptured abdominal aortic aneurysm continues to have a high mortality. Such patients require expeditious operations to repair the ruptured segment rather than attempts to deal with all coexisting disease. The use of endovascular techniques obviates the need for open surgery to repair iliac aneurysms. We report two patients who, after successful repair of ruptured abdominal aortic aneurysms, had three iliac artery aneurysms treated successfully by embolisation in one case and percutaneous insertion of a self expandable stent graft in two cases. The issues that arise from such an approach are discussed with a review of the literature.

Aged↗
PubMed1996

Radioimmunoassay of Antarelix, a luteinizing hormone releasing-hormone antagonist, in plasma and its application for pharmacokinetic study in dogs.

A procedure for the radioimmunoassay (RIA) of Antarelix (teverelix) in plasma has been developed for the pharmacokinetic study of this potent LHRH antagonist in dogs. Antiserum was produced by coupling the deamidated Antarelix analog to bovine serum albumin by a carbodiimide reaction and immunizing rabbits with the conjugate. The crossreactivity of the antiserum with LHRH, LHRH agonist Metereline and LHRH antagonists tested was negligible, except for Antide which displayed a crossreactivity of 33%. No crossreactivity with Antarelix metabolites could be detected. The RIA is suitable for the direct determination of Antarelix in plasma, with a minimum detectable level of 1.12 fmol/assay. The accuracy and precision of the method were assessed with plasma samples spiked with Antarelix at concentrations ranging from 0.4 to 6.4 pmol/ml. The recovery was 104.8% with intra- and interassay CV between 1 and 3.7%. Pharmacokinetic profiles of Antarelix in dogs were established following an i.v. or a s.c. dose of 10 micrograms/kg.

Animals↗
PubMed1996

Kinin-induced prolongation of action-potential duration in right ventricular muscle from rat: involvement of B1 and B2 receptors.

Previous work has shown that, in rat ventricular muscle, bradykinin (BK) causes a dose-dependent increase in action potential duration (APD), an action that may be responsible for APD prolongation by captopril (kininase II). To determine which kinin receptor might be involved in APD prolongation, we studied the effects of B1- and B2-receptor agonists, as well as those of antagonists and mergepta (a kininase I inhibitor) added during BK superfusion. Action potentials were recorded by using the standard glass microelectrode technique in rat ventricular muscle preparations. Action-potential characteristics were compared between preparations superfused with peptide/drug-free Tyrode's solution (control group) and preparations superfused with peptide/drug-containing solution. APD was significantly longer in preparations superfused with BK (10(-8) M) than in the control group. The APD prolongation induced by BK, a known B2-receptor agonist, was significantly reduced by Hoe 140 (a B2 antagonist) and also by Lys[Leu8]des-Arg9-BK (a B1 antagonist), an action presumably related to inhibition of B1 receptor stimulation by the BK metabolite des-Arg9-BK. When mergepta was added in the presence of BK, APD prolongation by BK was significantly reduced, an effect that could have been related to reduced B1-receptor stimulation after inhibition of the endogenous generation of des-Arg9-BK by kininase I. Sar4-[d-Phe8]des-Arg9-BK, a B1-receptor agonist that is not degraded by kininase II, also prolonged APD. We conclude that both B1 and B2 receptors may be involved in APD prolongation induced in rat ventricular muscle preparations.

3-Mercaptopropionic Acid↗
PubMed1996

Nitrofurantoin-induced hepatic and pulmonary biochemical changes in mice fed different vitamin E doses.

The hepatic and pulmonary effects of nitrofurantoin (40 mg/kg, intraperitoneally) were determined at 4 and 24 hr following its administration in mice fed for 10 weeks with a vitamin E sufficient, deficient or enriched diet. Liver glutathione (GSH) was reduced by nitrofurantoin at 4 hr but was unchanged 20 hr later. Nitrofurantoin did not affect liver glutathione peroxidase, glutathione reductase or superoxide dismutase activities. Liver catalase activities were decreased by nitrofurantoin at 4 hr. Lung GSH levels were increased whilst glutathione peroxidase activity was decreased at 4 and 24 hr. Lung glutathione reductase activity was reduced in certain groups. Nitrofurantoin did not affect lung superoxide dismutase, but catalase was decreased at 24 hr. Liver malondialdehyde levels were increased by nitrofurantoin in the vitamin E deficient group whilst lung malondialdehyde levels remained unchanged. Both liver and lung malondialdehyde levels were unaffected by vitamin E supplementation when compared to the vitamin E-sufficient group. These results suggest that nitrofurantoin (40 mg/kg) was deleterious to the liver and lung. Nitrofurantoin-induced lipid peroxidation was seen in vitamin E deficiency but an increase in dietary vitamin E content did not provide additional protection compared to the recommended daily allowance. The antioxidant activities of alpha-tocopherol and gamma-enriched tocotrienol were similar.

Animals↗
PubMed1996

Serum interspecies differences in metabolic pathways of bradykinin and [des-Arg9]BK: influence of enalaprilat.

Among the different enzymes responsible for the metabolism of bradykinin (BK), three peptidases look relevant in vivo: kininase I (KI), which transforms BK into its active metabolite, [des-Arg9]BK; kininase II (KII); and neutral endopeptidase, which inactivate BK and [des-Arg9]BK. The in vitro incubation of BK and [des-Arg9]BK in the serum of four species with or without enalaprilat and the quantification of the immunoreactivity of both peptides at different time intervals allowed the measurement of the kinetic parameters characterizing their metabolic pathways. Highly sensitive chemiluminescent enzyme immunoassays were used to measure the residual concentrations of BK and [des-Arg9]BK. Half-life (t1/2) of BK showed significant difference among species: rats (10 +/- 1 s) = dogs (13 +/- 1 s) < rabbits (31 +/- 1 s) < humans (49 +/- 2 s). t1/2 values of [des-Arg9]BK were also species dependent: rats (96 +/- 6 s) < < rabbits (314 +/- 6 s) = dogs (323 +/- 11 s) = humans (325 +/- 12 s). Enalaprilat significantly prevented the rapid BK and [des-Arg9]BK degradation in all species except that of [des-Arg9]BK in rat serum. Relative amount of BK hydrolyzed by serum KII was given as follows: rabbits (93.7 +/- 14.8%) = rats (83.6 +/- 6.7%) = humans (76.0 +/- 7.5%) > dogs (50.0 +/- 3.9%). Its importance in the hydrolysis of [des-Arg9]BK was 5.2 +/- 0.5% in rats < < 33.9 +/- 1.5% in humans < 52.0 +/- 1.1% in rabbits < 65.1 +/- 3.4% in dogs. The participation of serum KI in the transformation of BK into [des-Arg9]BK was dogs (67.2 +/- 5.3%) > > humans (3.4 +/- 1.2%) = rabbits (1.8 +/- 0.2%) = rats (1.4 +/- 0.3%). Finally, no significant difference on t1/2 values for BK and [des-Arg9]BK could be demonstrated between serum and plasma treated with either sodium citrate or a thrombin inhibitor. These results revealed striking species differences in the serum metabolism of kinins that could address at least partially some of the controversial data related to the cardioprotective role of kinins.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1996

A comparison of methods for heat-mediated antigen retrieval for immunoelectron microscopy: demonstration of cytokeratin No. 18 in normal and neoplastic hepatocytes.

Postembedding antigen retrieval is a well established technique for immunoelectron microscopy; however, many antigens cannot be detected without additional unmasking procedures. This study was undertaken to determine whether microwave oven heating, autoclaving, and pressurized boiling, which are well recognized methods of antigen retrieval for light microscopy, and simple boiling can also be used in electron microscopy. We investigated neoplastic and normal hepatocytes using a commercially available mouse monoclonal antibody against cytokeratin NO. 18 (CK 18). The tissue was fixed in paraformaldehyde/glutaraldehyde and embedded in Lowicryl K4M at -40 C. Ultrathin sections in various buffers were exposed to heat using one of four methods or to pronase at 37 C before incubation with the primary antibody. The secondary antibody was gold-labeled goat anti-mouse antibody. Sections that were not heat-treated remained unlabeled, but heat-treated sections showed immunoreactivity located mainly at the cytoplasmic periphery. Some of the gold particles lay in direct or loose association with intermediate filaments, some were seen in the area of desmosomes, and some did not appear related to any structures. No difference in immunostaining was found among the four methods of heat treatment. The citrate buffer, pH 6.0, and 10 mM EDTA, pH 8.0, generated the best labeling results.

Antigens↗
PubMed1996

Chloramphenicol and the inflammatory response in the rat. Upregulation of the gene for T2-kininogen in liver.

Recent observations have indicated that cytokine and glucocorticoid mediators of the inflammatory response in mammals interfere with mitochondrial respiratory capacity of cultured cells. Here, we report studies on the effect of the antibiotic chloramphenicol (CAP), a potent mitochondrial protein synthesis and respiratory inhibitor, on the inflammatory response in the rat. CAP was injected daily (i.p.) at doses of 30, 100 and 300 mg kg-1 during a period of 10 days. Acute inflammation was induced on day 10 by s.c. injection of carrageenan into the hindpaws. Paw edema reaction and liver and serum expression of the acute phase protein T-kininogen were used as markers of the local and systemic inflammatory response, respectively. Albumin was selected as a liver protein whose expression is little or not affected in inflamed rats. We found that the swelling process induced locally by carrageenan injection was significantly altered in rats treated with CAP at the dose level of 300 mg kg-1. The inhibitory effect of CAP was transient, extending up to 3 hr after carrageenan injection. CAP was observed also to alter the mitochondrial respiratory capacity of liver cells, reducing cytochrome C oxidase activity up to 50%. In contrast, liver immunoreactive T-kininogen content and the T2-kininogen mRNA steady-state level were found to increase in a dose-related manner in CAP-treated animals. These values were slightly different from those recorded in control rats inflamed with carrageenan. No significant increase of T-kininogen serum content was seen at all dose levels of CAP injected. Among inflamed animals, those exposed long-term to CAP had elevated liver and serum T-kininogen content and t2-kininogen mRNA steady-state levels. Expression of the gene for albumin was not affected in rats treated or not with CAP. The present observations indicate that CAP influences both local and systemic inflammatory responses in the rat.

Animals↗
PubMed1995

Quantification of des-Arg9-bradykinin using a chemiluminescence enzyme immunoassay: application to its kinetic profile during plasma activation.

There is a renewed interest in the kininase I pathway of kinin metabolism, because des-Arg9-bradykinin (des-Arg9-BK) and des-Arg10-Lys-BK are selective and potent agonists of the B1 receptors, that are apparently upregulated by tissue injury. We have developed a polyclonal rabbit antiserum against des-Arg10-Lys-BK. In a radioimmunoassay for des-Arg10-Lys-BK, this antiserum exhibited high specificity. Notably, native kinins with the C-terminal Arg residue, bradykinin (BK) and Lys-BK, did not cross-react to a significant extent, whereas des-Arg9-BK and digoxigenin (DIG)-des-Arg9-BK exhibited a complete cross-reactivity. The antibodies were used to set up a sensitive chemiluminescence enzyme immunoassay (CLEIA) using the DIG-anti-DIG system as intermediate for the revelation of the immune complexes. The detection limit and the half-maximal saturation concentration for des-Arg9-BK were 27 and 1530 fmol/ml respectively. This assay, as well as another for BK quantification, have been applied in vitro to rabbit plasma activated by kaolin. The conversion of BK into des-Arg9-BK was generally efficient, and the persistence and concentration of both peptides were increased in the presence of enalaprilat an inhibitor of the angiotensin converting enzyme (ACEI). Rabbits treated with bacterial lipopolysaccharide exhibited an increase of plasma immunoreactive des-Arg9-BK that was potentiated in animals also treated with ACEI. This CLEIA for des-Arg9-BK is a new analytical tool applicable to analyze of the kininase I metabolites of kinins in vitro and in vivo. Measurements of des-Arg9-BK may be useful indicators of the kallikrein-kinin system activation.

Amino Acid Sequence↗