Biomedical subjects
Publications and source records attributed to L Lion.
We report the case of splenic subcapsular haematoma, that happens to a woman after three months. Breaking and fistulation of the splenic haematoma into the gastric cavity and its subsequent evacuation made it first identify as digestive haemorrhage.
The topology of the binding site has been studied for two monoclonal antibodies 13G10 and 14H7, elicited against iron(III)-alpha,alpha,alpha,beta-meso-tetrakis(ortho-carboxyphenyl)porph yrin [alpha,alpha,alpha, beta-Fe[(o-COOHPh)4-porphyrin]], and which exhibit in the presence of this alpha,alpha,alpha, beta-Fe[(o-COOHPh)4-porphyrin] cofactor a peroxidase activity. A comparison of the dissociation constants of the complexes of 13G10 and 14H7 with various tetra-aryl-substituted porphyrin has shown that: (a) the central iron(III) atom of alpha,alpha,alpha,beta-Fe[(o-COOHPh)4-porphyrin] is not recognized by either of the two antibodies; and (b) the ortho-carboxylate substituents of the meso-phenyl rings of alpha,alpha,alpha, beta-Fe[(o-COOHPh)4-porphyrin] are essential for the recognition of the porphyrin by 13G10 and 14H7. Measurement of the dissociation constants for the complexes of 13G10 and 14H7 with the four atropoisomers of (o-COOHPh)4-porphyrinH2 as well as mono- and di-ortho-carboxyphenyl-substituted porphyrins suggests that the three carboxylates in the alpha, alpha, beta position are recognized by both 13G10 and 14H7 with the two in the alpha, beta positions more strongly bound to the antibody protein. Accordingly, the topology of the active site of 13G10 and 14H7 has roughly two-thirds of the alpha,alpha,alpha,beta-Fe[(o-COOHPh)4-porphyrin] cofactor inserted into the binding site of the antibodies, with one of the aryl ring remaining outside. Three of the carboxylates are bound to the protein but no amino acid residue acts as an axial ligand to the iron atom. Chemical modification of lysine, histidine, tryptophan and arginine residues has shown that only modification of arginine residues causes a decrease in both the binding of alpha,alpha,alpha, beta-Fe[(o-COOHPh)4-porphyrin] and the peroxidase activity of both antibodies. Consequently, at least one of the carboxylates of the hapten is bound to an arginine residue and no amino acids such as lysine, histidine or tryptophan participate in the catalysis of the heterolytic cleavage of the O-O bond of H2O2. In addition, the amino acid sequence of both antibodies not only reveals the presence of arginine residues, which could be those involved in the binding of the carboxylates of the hapten, but also the presence of several amino acids in the complementary determining regions which could bind other carboxylates through a network of H bonds.
Besides existing models of chemical or biotechnological origin for hemoproteins like peroxidases and cytochromes P450, catalytic antibodies (Abs) with a metalloporphyrin cofactor represent a promising alternative route to catalysts tailored for selective oxidation reactions. A brief overview of the literature shows that, until now, the first strategy for obtaining such artificial hemoproteins has been to produce antiporphyrin Abs, raised against various free-base, N-substituted, Sn-, Pd-, or Fe-porphyrins. Four of them exhibited, in the presence of the corresponding Fe-porphyrin cofactor, a significant peroxidase activity, with kcat/K(m) values of 10(2) to 5 x 10(3)/M/s. This value remained low when compared to that of peroxidases, probably because neither a proximal ligand of the Fe, nor amino acid residues participating in the catalysis of the heterolytic cleavage of the O-O bond of H2O2, have been induced in those Abs. This strategy has been shown to be insufficient for the elaboration of effective models of cytochromes P450, because only one set of Abs, raised against meso-tetrakis(para-carboxyvinylphenyl)porphyrin, was reported to catalyze the nonstereoselective oxidation of styrene by iodosyl benzene using a Mn-porphyrin cofactor, and attempts to generate Abs having binding sites for both the substrate and the metalloporphyrin cofactor, using as a hapten a porphyrin covalently linked to the substrate, were not successful. A second strategy is then proposed, which involves the chemical labeling of antisubstrate Abs with a metalloporphyrin. As an example, preliminary results are presented on the covalent linkage of an Fe-porphyrin to an antiestradiol Ab, in order to obtain semisynthetic catalytic Abs able to catalyze the selective oxidation of steroids.
We report the case of a 54-year-old man without previous medical history who presented with sudden vertical diplopia and frontal headache. Clinical examination and Lancaster's test were consistent with superior rectus muscle palsy. Brain CT scan, MRI and CSF examination were normal. Cerebral angiography revealed a dural arteriovenous fistula at the base of the anterior cranial fossa with bilateral arterial supply from small branches of the ophthalmic artery. The causal relationship, the pathophysiology and the therapeutic approaches are discussed.
Reperfusion-induced ventricular fibrillation has been demonstrated in animal models of myocardial ischaemia, but no evidence exists for this in humans. The European Myocardial Infarction Project compared the efficacy and safety of pre-hospital thrombolytic therapy with that of hospital therapy. The objective of this study was to investigate the occurrence of reperfusion-induced ventricular fibrillation in acute myocardial infarction patients following thrombolytic therapy. In a double-blind multicentre trial, eligible patients were randomized to receive anistreplase at home followed by placebo in the hospital (A/P group), or placebo followed by anistreplase (P/A group). The occurrence of ventricular fibrillation, and other adverse events were recorded on specific study forms and could be attributed to defined time intervals. The incidence of ventricular fibrillation in the A/P group was significantly higher following the pre-hospital injection than in the P/A group (2.5% vs 1.6%; P = 0.021); the situation was reversed following the hospital injection (3.6% vs 5.3%; P = 0.002). No relationship was found between this excess of ventricular fibrillation and the patients' condition, with the exception of the site of the infarct. These results suggest the existence of reperfusion-induced ventricular fibrillation in patients developing myocardial infarction who receive thrombolytic treatment.
We compared the efficacy and safety of three doses of beraprost sodium, an epoprostenol analogue, with placebo in the treatment of intermittent claudication (Fontaine's stage II). One hundred sixty-four patients were randomized to receive either placebo, 20 micrograms beraprost sodium (BPS60 group), 40 micrograms beraprost sodium (BPS120 group), or 60 micrograms beraprost sodium (BPS180 group) three times daily administered orally in a double-blind manner for 12 weeks. Treadmill exercise tests were performed twice during an initial selection phase (D-28 and D0) at week 10 (at trough beraprost concentration) and week 12 (at peak beraprost concentration) of the treatment phase. At week 10, all groups showed an increase in pain-free walking distance, and this distance was greatest in the BPS60 and BPS120 groups (p = 0.055). At week 12, a similar pattern was observed, and the difference was significant between the groups (p = 0.023). The most frequent adverse events reported were gastrointestinal disorders, headaches, skin disorders, and flushes. Patients who received either 60 or 120 micrograms of beraprost sodium daily had an increased pain-free walking distance. Further studies are required to investigate why the highest dose used (180 micrograms daily) showed lower efficacy. Having both vasodilating and antiplatelet properties and being able to increase pain-free walking distance in the short term, beraprost sodium is a promising drug for the treatment of intermittent claudication.
OBJECTIVE: To assess the equivalence of four antihypertensive treatments in patients with mild-to- moderate hypertension, and to compare the effects of those drugs on the subjective quality of life and clinical safety. DESIGN, SETTING AND PATIENTS: 653 patients aged > or = 18 years with untreated hypertension were randomly allocated to receive a combination of two diuretics (altizide and spironolactone), a beta-blocker (bisoprolol), a calcium antagonist (verapamil), or an angiotensin converting enzyme (ACE) inhibitor (enalapril). Follow-up lasted for 1 year. MAIN OUTCOME MEASURES: A composite outcome of the following measures was used to define success: attendance at the 12-month visit; at least nine supine DBP measurements during the study; and median supine DBP < 90 mmHg and a reduction of at least 10 mmHg compared with the baseline value. Failure was defined as one or more of those criteria not being fulfilled. Equivalence was concluded if the 95% confidence interval for the success rates differed between two groups by less than +/- 10%. Clinical safety and subjective quality of life were also assessed. RESULTS: No statistically significant differences in the change in DBP or systolic blood pressure were observed between the groups. The success rates were 43.9, 42.0, 32.5 and 43.9% in diuretic, beta-blocker, calcium antagonist and ACE inhibitor groups, respectively. Equivalence between the treatments could not be concluded, although analysis with a larger equivalence interval showed that some comparisons indicated equivalence. Significant improvement in satisfaction was observed for certain items for subjective quality of life at 1 month in the calcium antagonist treatment group, and significant differences in the responses to the clinical safety questionnaire were observed after 1-month follow-up in calcium antagonist and beta-blocker groups. Differences were no longer significant after 9 months. CONCLUSIONS: These results do not provide evidence on the basis of efficacy of blood pressure lowering or ability to increase short-term (1-year) safety and quality of life favouring any particular treatment among the studied drugs for newly diagnosed patients with mild-to-moderate hypertension.
The effect of an initial single-blind placebo period in a phase I clinical trial was assessed in 12 volunteers who underwent five weekly treatment periods, consisting of treatment on the first day and a six-day wash-out period. An initial single-blind placebo period was followed by three different single doses of a platelet-aggregation factor inhibitor and another placebo period, under a double-blind Latin square design. Reports of abnormal symptoms were collected using a questionnaire designed by our group. A total of 13 abnormal symptoms were reported during the first period and only nine for the following four periods, indicating a clear placebo period effect. These preliminary results suggest that an initial single-blind period may be usefully included in phase I clinical trials.
The aim of our study was to explore the effect of clonidine on the mouth to caecum transit time in healthy man. Hydrogen-breath test, using lactulose 10 g, was carried out in 10 healthy male volunteers, in double-blind conditions and in random sequences of medications, placebo or clonidine (0.3 mg per os). Clonidine increased the mouth to caecum transit time significantly (p = 0.013): from 85 +/- 12 min. (with placebo) to 139 +/- 16 min. (mean +/- SE). This study suggests that the antidiarrheal action of clonidine is due, at least in part, to effect on motility of the proximal gut.
We performed a survey to assess the feasibility of a placebo-controlled clinical trial of the treatment of recurrent ENT/respiratory tract infections in children, to assess the diversity of the drugs prescribed, and the acceptability of a clinical trial to homeopathic physicians. A mailed questionnaire was sent to 237 homeopathic physicians, asking for details of prescriptions for 10 consecutive children consulting for ENT/respiratory recurrent infections, and for two simulated cases. We also asked for their opinion about homeopathic treatment evaluation. Only 48 (20 per cent) questionnaires were returned completed. These gave 309 different acute treatments and 422 different preventive treatments for the 10 consecutive patients and 87 different prescriptions for the simulated cases. A total of 467 different drugs were used. The physicians who replied were favourable to the evaluation of homeopathic drugs, reluctant for the use of a placebo; and they would like to receive training in drug evaluation. Setting up a clinical trial in this field would require specific methodological and logistical adaptations, and a detailed training programme for the homeopathic doctors beforehand.
UNLABELLED: This study compares the loop diuretic piretanide 6 mg in a slow-release formulation (PIR) with hydrochlorothiazide 25 mg (HCT) and the fixed combination altizide 15 mg-spironolactone 25 mg (ALT-SP) in hypertension. 1105 mild to moderate hypertensive patients entered a three-week placebo wash-out period; 899 were randomized in a 6-month, double-blind, parallel group treatment phase; 800 completed the study. Primary end-points; serum potassium concentration and quality of life at one month; secondary end-points: ionic, renal and metabolic variables; blood pressure (BP) measurements. HCT and ALT-SP were compared only to PIR using Dunnett's or chi 2 tests. RESULTS: No difference was found for the overall quality of life. No change of serum potassium concentration at one month was found in PIR while small decreases were detected with ALT-SP (-0.1 mM) and HCT (-0.26 mM). Serum creatinine concentration increased significantly in ALT-SP when compared to PIR. All the drugs were effective in reducing BP: HCT had a higher rate of responders than PIR with similar mean BP falls and ALT-SP induced greater falls in blood pressure. CONCLUSION: PIR proves to be a potent antihypertensive drug without significant effect on serum electrolytes, plasma glucose and lipids. HCT was slightly more potent but induced a fall in serum potassium concentration with a significant risk of hypokalaemia. The addition of SP to ALT led to a more potent diuretic with a higher level of serum potassium and plasma creatinine disturbances.