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D Cortes

Publications and source records attributed to D Cortes.

At least 73 records · Page 4Linked to original sources
PubMed1993

Antispasmodic activity of benzylisoquinoline alkaloids analogous to papaverine.

In vitro, reticuline, norarmepavine, coclaurine, and papaverine competitively antagonize the uterine muscular contractions induced by acetylcholine and calcium. The antagonism is more efficient for the alkaloid coclaurine which is even stronger than papaverine. The pA2 values obtained with each of the four alkaloids for both agents, acetylcholine and calcium, respectively, were as follows: reticuline (5.35 and 4.81), norarmepavine (5.55 and 4.09), coclaurine (7.42 and 6.91), papaverine (5.32 and 6.23). The two components, phasic and tonic, of the response of the vas deferens to potassium are reduced by the four alkaloids. The reduction is greater for the tonic phase, with the following IC50 values: reticuline 474 microM, norarmepavine 101 microM, coclaurine 68.9 microM, and papaverine 14.3 microM. The antispasmodic activity of the three alkaloids, similar to papaverine, is related to an inhibiting effect of extracellular calcium, an intracellular effect, or both.

Alkaloids↗
PubMed1993

Investigations of the dual contractile/relaxant properties showed by antioquine in rat aorta.

1. In the present study we assessed the activity of antioquine, a bisbenzyltetrahydroisoquinoline alkaloid isolated from Pseudoxandra sclerocarpa, by examining its effects on the contractile activity of rat isolated aorta, specific binding of [3H]-(+)-cis-diltiazem, [3H]-nitrendipine and [3H]-prazosin to cerebral cortical membranes and the different molecular forms of cyclic nucleotide phosphodiesterases (PDE) isolated from bovine aorta. 2. Contractions in rat aorta induced by high concentrations of KCl (80 mM) and noradrenaline (1 microM) were inhibited by antioquine in a concentration-dependent manner (0.1 microM- 300 microM). The alkaloid appeared more potent against KCl-induced contractions. This inhibitory effect was observed at both 37 degrees C and 25 degrees C. 3. Paradoxically, at the highest concentration tested (300 microM) antioquine induced a contractile response of similar magnitude in the presence and absence of extracellular calcium, at 37 degrees C. This activity was greatly attenuated at 25 degrees C. Antioquine-induced contractions were not inhibited by prazosin (0.1 microM), nifedipine (1 microM) or diltiazem (100 microM). On the contrary, prazosin and nifedipine slightly increased the contractions in the presence of extracellular calcium. Papaverine (100 microM) partially inhibited the contractile response to antioquine both in the presence and absence of extracellular calcium. 4. At 25 degrees C, in Ca(2+)-free solution, antioquine (300 microM) did not modify the contractile response (phasic and tonic) evoked by noradrenaline, but increased the phasic contraction induced by caffeine. At 37 degrees C, the contraction elicited by antioquine made it impossible to observe the noradrenaline-induced one. 5. Antioquine showed affinity for the [3H]-prazosin binding site and for the [3H]-(+)-cis-diltiazembinding site of the Ca2+-channel receptor complex, but had no effect at the dihydropyridine binding site in rat cerebral cortex.6. Antioquine weakly inhibited some PDE forms isolated from bovine aorta: a CaM-PDE (PDE I)which preferentially hydrolyzes cyclic GMP and is activated by calmodulin, and a rolipram-sensitive cyclic AMP-PDE (PDE IV) which hydrolyzed cyclic AMP. Antioquine did not exert any inhibitory effect on the other forms of PDE, a cyclic GMP selective form (PDE V) and a low Km cyclic AMP-PDEthat is inhibited by cyclic GMP (CGI-PDE, PDE III).7. The present work provides evidence that antioquine has properties both as a calcium entry blocker(possibly through the benzothiazepine recognition site in the calcium channel) and as a contractile agent.Its mechanism of action as a contractile agent is not related to Ca2+-entry and is hypothetically similar to that of calyculin-A or okadaic acid. The possible involvement of a-adrenoceptors in this paradoxical effect cannot be excluded. The rigidity of the molecule provides an interesting model for analyzing this contractile mechanism and the intracellular processes involved.

Alkaloids↗
PubMed1993

Comparative study of the rat uterine smooth muscle relaxant activity of three bisbenzyltetrahydroisoquinolines with tetrandrine.

The relaxant activity of three bisbenzyltetrahydroisoquinolines--obaberine, popisonine and lindoldhamine--was examined in rat isolated uterus and their inhibitory potencies were compared with that of tetrandrine. All alkaloids tested relaxed KCl-depolarized rat uterus and totally or partially inhibited oxytocin-induced rhythmic contractions. The degree of methylation of the free phenolic hydroxy groups and the loss of one diarylether bridge influence the potency of relaxant action of these alkaloids. Only alkaloids with absolute configuration 1R,1'S or 1R1'R acted intracellularly, promoting relaxation of contractile responses induced by oxytocin or vanadate in a Ca(2+)-free medium.

Alkaloids↗
PubMed1992

Selective chiral inhibition of Ca2+ entry promoted by bisbenzyltetrahydroisoquinolines in rat uterus.

The effects of diltiazem and six bisbenzyltetrahydroisoquinoline alkaloids (antioquine, 7-O-methylantioquine, dimethylantioquine, monterine, granjine and cordobimine) were studied in rat isolated uterus in order to clarify the mechanisms of their relaxant actions. All the compounds tested completely relaxed KCl-induced contractions and totally or partially inhibited oxytocin-induced rhythmic contractions. Only alkaloids with absolute configurations (1R,1'S or 1R,1'R) acted intracellularly, promoting relaxation of contractile responses induced by oxytocin in a Ca(2+)-free medium, as does papaverine. Alkaloids of the antioquine series (1S,1'R) selectively inhibited Ca2+ entry. The great rigidity of these structures and their stereoselective action make these alkaloids useful in studies of the conformational features of the Ca2+ channel.

Alkaloids↗
PubMed1992

Displacement activity of bisbenzylisoquinoline alkaloids at striatal 3H-SCH 23390 and 3H-raclopride binding sites.

Fifteen bisbenzylisoquinoline alkaloids (BBIQ) with one ether bridge (thaligrisine [1], berbamunine [2], dimethylgrisabine [3], pampulhamine [4], and methyl-dauricine [5]), with two ether bridges (homoaromoline, isotetrandrine, and obaberine), with one ether bridge and one biphenyl bridge (oxandrine, dimethylpseudoxandrine, pseudoxandrine, and antioquine) or secoderivatives (secoobaberine, secoantioquine, and secolucidine), were tested for their ability to displace 3H-raclopride or 3H-SCH 23390 from their specific dopaminergic binding sites to rat striatal membranes. The most active compounds were found in the group of BBIQs with one ether bridge. Inactive or weakly active compounds were found in this group of BBIQs with one ether bridge and in the other groups. Analysis of tridimensional representations indicates that the differnt activities among the BBIQs with one ether bridge could be related to strong differences between the spatial occupancy of these compounds according to their stereochemistry.

Alkaloids↗
PubMed1992

Selective inhibition of calcium entry induced by benzylisoquinolines in rat smooth muscle.

The mechanism of relaxant activity of six benzylisoquinolines was examined in order to determine the minimal structural requirements that enable these compounds to have either a non-specific action like papaverine or an inhibitory activity on calcium entry via potential-operated channels. All the alkaloids tested totally or partially relaxed KCl-depolarized rat uterus and inhibited oxytocin-induced rhythmic contractions. Only glaucine and laudanosine inhibited K(+)-induced uterine contractions more than oxytocin-induced uterine contractions. In Ca(+)-free medium, sustained contractions induced by oxytocin or vanadate were relaxed by the alkaloids tested except for glaucine and laudanosine indicating no inhibitory effect on intracellular calcium release. Those alkaloids containing an unsaturated heterocyclic ring (papaverine, papaverinol, papaveraldine, N-methylpapaverine and dehydropapaverine) exhibited a more specific activity than those with a tetrahydroisoquinoline ring.

Alkaloids↗
PubMed1991

Inhibition of calcium entry induced by cularines and isocrasifoline in uterine smooth muscle.

The effects of nifedipine, papaverine and four benzylisoquinoline alkaloids (cularine, cularidine, celtisine and isocrasifoline) were studied in isolated rat uterus in order to clarify the mechanism of their relaxant action. All the compounds tested completely relaxed KCl-induced contractions and totally or partially inhibited oxytocin-induced rhythmic contractions. Only papaverine acted intracellularly, promoting relaxation of contractile responses induced by oxytocin or vanadate in a Ca(2+)-free medium. In spite of the structural relationship between papaverine and the other alkaloids, the mechanism of their relaxant action is not the same. The activities of cularine derivatives and of isocrasifoline were similar to that of nifedipine.

Alkaloids↗
PubMed1991

Antiparasitic activity of Annona muricata and Annona cherimolia seeds.

Methanolic extracts of Annona muricata and A. cherimolia (Annonaceae) seeds were tested for antiparasitic activity against E. histolytica, N. brasiliensis, M. dessetae and A. salina. The acetogenins isolated from these extracts are found to be responsible for the important activity on infective larvae of Molinema desetae.

Animals↗
PubMed1991

Histology of testicular biopsies taken at operation for bilateral maldescended testes in relation to fertility in adulthood.

A total of 91 boys underwent bilateral orchiopexy with testicular biopsy. The percentage of tubular transverse sections containing spermatogonia, the fertility index (FI) and the number of spermatogonia per tubular transverse section (S/T) were measured and expressed as a percentage of the minimum normal value (FI% and S/T%, respectively). The maximum and mean of the 2 FI% and S/T% values were noted for each patient. At follow-up, testicular volume was measured in 73 men; 71 of these gave a blood sample for FSH and 67 provided specimens of semen for analysis. The maximum and the mean FI% and S/T% values of the patients were positively correlated to maximal sperm density and to volume of pair of testes and negatively correlated to serum FSH. It seems reasonable to use these histological parameters as prognostic indices of fertility potential. In adulthood only 11 patients had sperm density greater than or equal to 20 million/ml, 37 had normal serum FSH and 29 had bilateral testicular volume greater than or equal to 15 ml. Patients with both testes originally placed in the superficial inguinal pouch at surgical exploration had a higher maximal sperm density than the rest of the study group.

Adolescent↗
PubMed1990

Direct mixed antiglobulin reaction (MAR) test in semen at follow-up after testicular biopsy of maldescended testes operated in puberty.

In thirty patients bilateral orchiopexy was performed in puberty. At the operation twenty-five patients underwent bilateral testicular biopsies, and five patients underwent unilateral biopsies only. In adulthood the semen was analysed for antisperm antibodies by the direct mixed antiglobulin reaction (MAR) IgG test. In none of the cases a positive direct MAR IgG test was found.

Adolescent↗
PubMed1990

Effects of cularine and other isoquinoline alkaloids on guinea-pig trachea and human bronchus.

The relaxant effects of the isoquinoline alkaloids, cularine, antioquine, obaberine and 6, 7-dimethoxy-1, 2, 3, 4-tetrahydroisoquinoline, with structures related to that of papaverine, have been studied on the guinea-pig isolated trachea and human bronchus against contractions induced by acetylcholine (ACh), histamine, neurokinin A (NKA) and KCl. These effects were compared with those of papaverine and theophylline. Among the alkaloids tested, the most potent was cularine, the relaxant activity of which, in terms of pD2, was between those of papaverine and theophylline. The results showed that for the guinea-pig isolated trachea and the human bronchus, the cularine concentrations required to inhibit K(+)-induced contractions were close to those necessary to counteract ACh-, histamine- and NKA-induced contractions. The relaxant activity of cularine was not modified when it was tested on tracheal preparations under resting tone or after epithelium removal. In addition, cularine was able to inhibit Ca2(+)-induced contractions in a Ca2(+)-free, K(+)-enriched solution at the same concentrations as those which inhibited the action of the different contractile agents in normal Krebs solution. All these data show that cularine displays non-specific antispasmogenic activity on guinea-pig and human airways. The lower relaxant activity (pD2) of cularine compared with papaverine suggests the importance of free rotation of the isoquinoline-benzyl ring linkage as well as of the degree of hydrogenation of the heterocyclic ring in the spasmolytic effects of isoquinoline compounds.

Adenosine↗
PubMed1990

Histological versus stereological methods applied at spermatogonia during normal human development.

The number of spermatogonia per tubular transverse section (S/T), and the percentage of seminiferous tubulus containing spermatogonia (the fertility index (FI] were measured in 40 pairs of normal autopsy testes aged 28 weeks of gestation-40 years. S/T and FI showed similar changes during the whole period, and were minimal between 1 and 4 years. The number of spermatogonia per testis (S/testis) and the number of spermatogonia per cm3 testis tissue (S/cm3) were estimated by stereological methods in the same testes. S/T and FI respectively were significantly correlated both to S/testis and S/cm3. So quantification of spermatogonia by S/T or FI measurement is a reasonable alternative to stereological examinations.

Adolescent↗
PubMed1988

[Active antihelminitic alkaloids: active in vitro against Leishmanic Tropica the protozoa involved in leishmaniasis].

Leishmaniasis caused by protozoan Leishmania ssp., is an endemic parasitic disease in Central and South America. The chemotherapeutic agents against Leishmania ssp. (pentavalent antimony compounds, pentamidine and amphothericine B) are toxic and expensive products. Basing on the Bolivian folk medicine, we tried to find new active principles. Fourteen isoquinoline alkaloids, especially bisbenzylisoquinoline alkaloids extracted from Annonaceae, Berberidaceae, Hernandiaceae and Menispermaceae, demonstrate highly effective activity against this protozoan. Among them gyrocarpine, daphnandrine and obaberine seem to be of particular interest. The therapeutic effect was studied by biological assays on culture forms in vitro three strains of Leishmania, L. donovani, L. braziliensis (cutaneous and mucocutaneous leishmaniasis), L. mexicana amazonensis (cutaneous) and L. donovani (visceral leishmaniasis).

Alkaloids↗
PubMed1988

[ Active trypanocidal alkaloids, bisbenzylisoquinoles ii. active in vitro against trypanosoma cruzi the agent responsible for trypanosomiasis, south america].

Chagas disease caused by the protozoan Trypanosoma cruzi is an endemic parasitic disease in Central and South America. The chemotherapeutic agents against Trypanosoma cruzi (imidazol compounds, lampit and benznidazol) are not very convenient products. Since it is known that protozoan Trypanosoma are close to Leishmania we studied the action of 14 bisbenzylisoquinoline alkaloids, in vitro, on three strains of T. cruzi (Tulahuen, C8C11, and 1979 CL1). As in the case of Leishmania, gyrocarpine, daphnandrine and obaberine showed an interesting activity and we judge them to be worthy of in vivo assays.

Alkaloids↗
PubMed1987

Proliferation of Sertoli cells during development of the human testis assessed by stereological methods.

Sertoli cells were studied using stereological methods in testes obtained from five children who were stillborn, and 31 individuals between 3 months and 40 years of age, who had suffered from sudden, unexpected death. The mean nuclear volume of the Sertoli cells, the numerical density of Sertoli cells, and the total number of Sertoli cells per individual were determined by point- and profile-counting of 0.5 micron sections. The nuclear volume of Sertoli cells increased from a median of 120 microns3 (range 53-130) during the period of 3 months to 10 years to 210 microns3 (170-260) in adults (greater than 25 years). The numerical density of Sertoli cells decreased from a median of 1200 X 10(6)/cm3 (870-1400) during childhood (3 months to 10 years) to 140 X 10(6)/cm3 (110-260) in adults (greater than 25 years). The total number of Sertoli cells per individual increased significantly from a median of 260 X 10(6) (130-520) during the late foetal period to 1500 X 10(6) (850-2900) in individuals from 3 months to 10 years of age. A further increase was found during puberty as the number of Sertoli cells in adults (greater than 25 years) was 3700 X 10(6) (2500-5600). These results indicate that significant qualitative and quantitative changes in the population of Sertoli cells take place after birth.

Adolescent↗