PubMed Health⌕ Search

Biomedical subjects

A Bermejo

Publications and source records attributed to A Bermejo.

At least 19 recordsLinked to original sources
PubMed2004

Enzymolysis approach to compare cu availability from human milk and infant formulas.

The purpose of the present paper is to develop an easy and quick in vitro method to compare copper availability from breast milk and infant formulas. This study focuses on the differences caused by the use of pH 2.0 (adult gastric pH) or pH 5.0 (newborn gastric pH) in the first stage of the enzymolysis. pH affects Cu solubility, a possible estimator of the availability. Selection of a digestor, times of enzymolysis, centrifugation parameters, and Cu determination by ETAAS were discussed as well. Percentage of Cu solubility was larger from breast milk (gastric pH 2.0, 65.3 +/- 14.0 vs 40.0 +/- 13.9%; gastric pH 5.0, 61.2 +/- 16.5 vs 26.6 +/- 10.3%), but the soluble content was larger from infant formulas for both pHs (gastric pH 2.0, 245.3 +/- 82.1 vs 113.0 +/- 103.4 ng mL(-1); gastric pH 2.0, 169.3 +/- 76.9 vs 75.3 +/- 21.9 vs ng mL(-1)).

Biological Availability↗
PubMed2001

Enantioselective syntheses of dopaminergic (R)- and (S)-benzyltetrahydroisoquinolines.

Optically pure (1S,R)- and (1R,S)-benzyltetrahydroisoquinolines (BTHIQs), 12a,b as the major diastereomers, were prepared by stereoselective reduction of the isoquinolinium salt possessing (R)- and (S)-phenylglycinol as the chiral auxiliary, respectively. The absolute configurations of (1S,R)-13a hydrochloride (O-debenzoylated derivative from 12a) and (1R,S)-12b diastereomers were unambiguously determined by single-crystal X-ray analysis. Reductive removal of the chiral auxiliary group, subsequent N-propylation, and cleavage of the methylenedioxy group furnished the optically active catecholamines (1S)-16a and (1R)-16b in good overall yield. We have separately prepared for the first time pairs of dopaminergic 1-BTHIQs enantiomers through a classical methodology in asymmetric synthesis. The (1S)-enantiomers (14a-16a) bind to D1 and D2 dopamine receptors with affinities 5-15 times higher than those of the corresponding (1R)-enantiomers (14b-16b). Moreover, (1S)-14a inhibits [3H]dopamine uptake with high affinity. It appears that synthesis and testing of (S)-enantiomers of BTHIQ are very important for the search for new active drugs at dopamine receptors.

Animals↗
PubMed2001

Copper fractionation by SEC-HPLC and ETAAS: study of breast milk and infant formulae whey used in lactation of full-term newborn infants.

This method will allow the determination of bound copper to low relative molecular mass compounds in milk. The milk whey obtained by ultracentrifugation was submitted to fractionation by size exclusion chromatography (SEC) on a TSK-Gel2000 (Toso Haas) column with a mobile phase of 0.2 M NH4NO3 + NH3, pH 6.7. Fractions of effluent corresponding to the protein peaks were collected and the copper content was determined by ETAAS. The method was sensitive (LOD 0.4 microgram l-1 and LOQ 1.5 micrograms l-1 in the fraction; LOQ 7.5-22.5 micrograms l-1 referred to the milk sample and depended on fraction volume) and precise (RSD +/- 10%). Media sample recoveries from the column were 101.2%. Cu was predominantly present in fractions corresponding to relative molecular mass 76 and 15 kDa of breast milk while copper was mostly found in fractions corresponding to 14 and 38 kDa of cow's milk-based infant formulae; moreover, copper was eluted in the relative molecular mass region < 6 kDa.

Chromatography, High Pressure Liquid↗
PubMed2000

Mechanism of vascular relaxation by thaligrisine: functional and binding assays.

In the present study we examine the mechanism by which thaligrisine, a bisbenzyltetrahydroisoquinoline alkaloid, inhibits the contractile response of vascular smooth muscle. The work includes functional studies on rat isolated aorta and tail artery precontracted with noradrenaline or KCl. In other experiments rat aorta was precontracted by caffeine in the presence or absence of extracellular Ca2+. In order to assess whether thaligrisine interacts directly with calcium channel binding sites or with alpha-adrenoceptors we examined the effect of the alkaloid on [3H]-(+)-cis diltiazem, [3H]-nitrendipine and [3H]-prazosin binding to cerebral cortical membranes. The functional studies showed that the alkaloid inhibited in a concentration-dependent manner the contractile response induced by depolarization in rat aorta (IC50 = 8.9+/-2.9 microM, n=5) and in tail artery (IC50 = 3.04+/-0.3 microM, n=6) or noradrenaline induced contraction in rat aorta (IC50 = 23.0+/-0.39 microM, n=9) and in tail artery (IC50 = 3.8+/-0.9 microM, n=7). In rat aorta, thaligrisine concentration-dependently inhibited noradrenaline-induced contraction in Ca2+-free solution (IC50 = 13.3 microM, n=18). The alkaloid also relaxed the spontaneous contractile response elicited by extracellular calcium after depletion of noradrenaline-sensitive intracellular stores (IC50 = 7.7 microM, n=4). The radioligand receptor-binding study showed that thaligrisine has higher affinity for [3H]-prazosin than for [3H]-(+)-cis-diltiazem binding sites, with Ki values of 0.048+/-0.007 microM and 1.5+/-1.1 microM respectively. [3H]-nitrendipine binding was not affected by thaligrisine. The present work provides evidence that thaligrisine shows higher affinity for [3H]-prazosin binding site than [3H]-(+)-cis-diltiazem binding sites, in contrast with tetrandrine and isotetrandrine that present similar affinity for both receptors. In functional studies thaligrisine, acted as an alpha1-adrenoceptor antagonist and as a Ca2+ channel blocker, relaxing noradrenaline or KCl-induced contractions in vascular smooth muscle. This compound specifically inhibits the refilling of internal Ca2+-stores sensitive to noradrenaline, by blocking Ca2+-entry through voltage-dependent Ca2+-channels.

Adrenergic alpha-Agonists↗
PubMed2000

Synthesis of N-diisopropyl phosphoryl benzyltetrahydroisoquinoline, a new class of mitochondrial complexes I and III inhibitors.

The synthesis of N-(O,O-diisopropylphosphoryl)-benzyltetrahydroisoquinoline (3) has been achieved in a 'one pot' procedure from imine (2) and diisopropyl-phosphorochloridate (1) generated in situ (POCl3 + iPrOH). Compound 3 is the first benzyltetrahydroisoquinoline derivative found to be a potent inhibitor of mitochondrial complexes I and III, and therefore it opens a new perspective with this series of compounds as they can be considered as new class of antitumor agents.

Animals↗
PubMed2000

3-acetylaltholactone and related styryl-lactones, mitochondrial respiratory chain inhibitors.

A novel furano-pyrone, 3-acetylaltholactone, and two other known styryl-lactones, altholactone and 5-acetoxyisogoniothalamin oxide, have been isolated from Goniothalamus arvensis (Annonaceae) stem bark. We report here the isolation and structural elucidation of these compounds with furane-pyrone and styryl-pyrone skeletons, postulating also for the first time their mechanism of cytotoxicity based on inhibition on mammalian mitochondrial respiratory chain.

Animals↗
PubMed2000

Solid-phase microextraction in the determination of methadone in human saliva by gas chromatography-mass spectrometry.

Solid-phase microextraction (SPME) with a 100-microm polydimethylsiloxane film fiber was applied to the determination of methadone and 2-ethylidine-3,3-diphenylpyrrolidine (EDDP) by GC-MS in human saliva and compared with liquid-liquid extraction. A shorter extraction time of 30 min with the fiber was obtained, speeding up the total analysis time. Linearity was found for SPME from 0.05 to 2.0 microg/mL (r = 0.9976 for methadone; r = 0.9988 for EDDP) with precision between 0.7 and 4.3% for saliva spiked with 0.2 and 1.5 microg/mL of methadone and EDDP. The limit of detection using SPME was 0.04 microg/mL for methadone and 0.008 microg/mL for EDDP. Analytical recoveries of SPME and liquid-liquid extraction ranged from 98.8 to 103.6%. The use of deuterated internal standard by both methods have yielded comparable results. Thus, the SPME method is highly accurate, precise, and useful for determination of methadone and EDDP in saliva.

Dimethylpolysiloxanes↗
PubMed1999

Cardiovascular effects of captopril and enalapril in obese Zucker rats.

The effects of two weeks of oral administration of the angiotensin-converting enzyme inhibitors captopril (a sulphydryl-containing drug) and enalapril (which lacks the sulphydryl group) on skeletal muscle glucose uptake, arterial blood pressure, cardiac hypertrophy, proteinuria and aortic vascular reactivity in obese Zucker rats were evaluated. Captopril (50 mg kg(-1) once daily) and enalapril (10 mg kg(-1) did not modify body weight gain or food or water intake. Both drugs decreased systolic blood pressure (157+/-6, 133+/-4 and 136+/-3 mm Hg, in vehicle-, captopril- and enalapril-treated rats, respectively), blood glucose (172+/-8 vs. 151+/-7 and 158+/-5 mg dl(-1), respectively), proteinuria (46+/-10 vs. 17+/-2 and 18+/-2.5 mg dl(-1), respectively) and heart weight (2.17+/-0.03, 1.98+/-0.02 and 1.99+/-0.04 mg g(-1)of body weight, respectively). Plasma insulin concentration was significantly increased by enalapril (17+/-2 ng ml(-1) vs. 9+/-2) but not by captopril (12+/-1). In the absence of insulin, the diaphragms from captopril- or enalapril-treated rats showed a significantly higher glucose uptake than that of controls (31% and 30% vs. control group, respectively). The presence of insulin in the incubation medium did not stimulate peripheral glucose uptake in the control group but significantly increased glucose uptake in diaphragms from captopril- or enalapril-treated rats (enhancement of glucose uptake vs. control: 52% and 43%, respectively). Endothelium-intact aortic rings from control Zucker rats showed a poor relaxant response to acetylcholine (maximal relaxation of 38.4+/-4.7%). Captopril significantly improved the endothelium-dependent vascular relaxation responses to acetylcholine and the endothelium-independent relaxation to the nitric oxide donor sodium nitroprusside whereas enalapril did not modify these relaxant responses. Neither captopril nor enalapril significantly affected the vascular contractile responses to the vasoconstrictors noradrenaline or KCl. In conclusion, the angiotensin-converting enzyme inhibitors captopril and enalapril reversed insulin resistance and the associated cardiovascular complications (cardiac hypertrophy, hypertension and proteinuria) in the obese Zucker rat, an animal model of non-insulin-dependent (type II) diabetes mellitus. However, only captopril, but not enalapril, improved the impaired endothelium-dependent and independent relaxant responses in the isolated rat aorta.

Acetylcholine↗
PubMed1999

Superficial mucocele: report of 4 cases.

Four cases of the lesion first described as superficial mucocele by Eveson in 1988 are reported. All of the lesions developed in adult women; two of the women had concurrent oral lichen planus. The mucoceles were found on the soft palate, the buccal mucosa, and the upper and lower labial mucosa. The etiologic factors and pathogenesis of this lesion are discussed.

Adult↗
PubMed1999

Semisynthesis and cytotoxicity of styryl-lactone derivatives.

The cytotoxicity and the cell-cycle action of altholactone (1), goniofufurone (2), and eight altholactone derivatives (5-12), were determined in vitro on L-1210 cells. Semisyntheses and structure-activity relationships of these compounds are described. The results of this study suggest that the cytotoxicity of altholactone (1), 11-nitro-altholactone (8), and 7-chloro-6,7-dihydroaltholactone (10) is due to the accumulation of the cells in the G2 + M phase of the cell cycle.

Animals↗
PubMed1998

Enantiospecific semisynthesis of (+)-almuheptolide-A, a novel natural heptolide inhibitor of the mammalian mitochondrial respiratory chain.

The development of novel styryl lactone derivatives as bioactive compounds and the semisynthesis of both 4,5-dialkoxylated eight-membered-ring lactones with a heptolide skeleton (almuheptolide-A (1) type) and 7-alkoxylated delta-lactones with a saturated furanopyrone skeleton (etharvensin (8) type) have been successfully achieved from the chiral unsaturated alpha-pyrone altholactone (7). This new method is a direct and one-step enantiospecific alkoxylation of altholactone (7) in concentrated acid medium, followed by formation of the eight-membered-ring zeta-lactone. The reaction mechanism operating in the synthesis of the heptolide skeleton is postulated to be a direct Michael-type addition. Concerted opening of both the alpha-pyrone and tetrahydrofuran rings and subsequent intramolecular rearrangement with the ring closure lead to almuheptolide-A (1). This compound (1) and its diacetated derivative (1a) showed potent and selective inhibitory activity toward mammalian mitochondrial respiratory chain complex I. This mechanism of action, reported here for the first time, provides a possible explanation for the cytotoxic and antitumor activities previously described for related natural compounds.

Animals↗
PubMed1998

Styryl-pyrones from Goniothalamus arvensis.

Two novel styrl-pyrones, (+)-garvensintriol and (+)-etharvendiol, together with a known cytotoxic furano-furone, (+)-goniofufurone, have been isolated from the stem bark of Goniothalamus arvensis. A different relative configuration, cis-erythro-erythro for garvensintriol and cis-threo-erythro for etharvendiol, is established, and their absolute stereochemistry is discussed.

Magnetic Resonance Spectroscopy↗
PubMed1997

[Value of analyzing reticulocyte subpopulations in polycythemia].

OBJECTIVE: The evaluation of the RNA content in reticulocytes by means of flow cytometry allows us to differentiate three reticulocyte populations by their degree of maturity: LFR, MFR and HFR. We have studied the value of those reticulocyte subpopulations for the differential diagnosis in polycythemia. PATIENTS AND METHODS: We have studied 25 polycythemia patients, 12 of these were diagnosed of polycythemia vera (PV) and 13 of secondary polycythemia (PS). Reticulocytes and their different reticulocyte populations were automatically analyzed by flow cytometry using the Sysmex R-2000 analyzer (TOA Corp. Japan). We calculated the reticulocyte maturity index (RMI) which is the percentage of the equation (MFR + HFR) x 100/LFR (9). We have also studied hemogram parameters (Hct, Hb, VCM, HCM, RDW, leukocytes and platelets), iron metabolism (serum iron, ferritin, transferrin and transferrin saturation index), and erythropoietin levels. The findings were statistically analyzed using the Pearson correlation test and the comparison tests of averages of independent samples (Student's t). RESULTS: Patients with PV present high RMI and MFR + HFR (medium and high fluorescence reticulocytes) as compared with secondary polycythemia . We did not find any correlation between RMI and other analytical parameters (erythropoietin, ferritin, serum iron, transferrin), except for the transferrin saturation index (TSI), with a correlation factor r: 0.5486 for p < 0.05. CONCLUSION: This higher proportion of younger reticulocytes in PV might be explained because they are a parameter that would reflect the expansion of erythropoietic bone progenitor cells, which would be more increased in PV than in PS. However, another possible explanation would consist in the existence of associated ferropenia in PVs, which lead to an increase in cytoplasmic levels of transferrin receptor mRNA.

Adult↗
PubMed1995

Effects of various isoquinoline alkaloids on in vitro 3H-dopamine uptake by rat striatal synaptosomes.

Various alkaloids having an isoquinoline skeleton from different species of the Annonaceae, Fumariacae, and Aristolochiacae (aporphine, cularine, benzylisoquinoline, and bisbenzylisoquinoline derivatives) were tested for their ability to inhibit in vitro 3H-dopamine uptake by rat striatal dopamine D1 3H-SCH 23390 AND D2 3H-raclopride binding sites. Except for some aporphine derivatives (anonaine [1], norstephalagine [2], isopiline [3]) and some bisbenzylisoquinoline alkaloids (dimethylgrisabine [27], antioquine [28], obaberine [29], isotetrandrine [30]) that displayed affinities of the same order as the reference compounds (nomifensine [38], amineptine [39], dexamphetamine [40]), the other tested products had low, or no, affinity on the 3H-dopamine uptake since, in comparison, its affinity at dopamine D1 3H-SCH 23390 and D2 3H-raclopride binding sites was low. These data suggest that it could be possible to synthesize anonaine-like products displaying intense dopamine-uptake inhibitory properties, which could lead to a potential antidepressant activity.

Alkaloids↗
PubMed1993

The pig as an animal model for experimentation on the temporomandibular articular complex.

A macroscopic study of the so-called temporomandibular joint of omnivorous mammals (pigs), carnivores (dogs and cats), rodents (rabbits and rats), and herbivores (cows, sheep, and goats) revealed the existence of two left and right temporomandibular articular complexes, each made up of a condylomeniscal and a meniscotemporal joint on either side, as in human beings. In all cases there is a combination of a condylar joint and a reciprocally fitting one. We conclude that the pig is the experimental animal model that most closely resembles human beings for the study of the cited articular structures.

Animals↗
PubMed1993

Community participation in disease control.

The main determinants of community participation in disease control programmes are identified and a framework with eleven variables is developed. Attention is drawn to the political background, community characteristics, the managerial capacity of the provider and the epidemiology of the disease. The framework is designed to guide health professionals in the systematic assessment and monitoring of participation in disease control programmes. Analysis of the Ghanaian Guinea Worm Eradication Programme and the Nicaraguan Tuberculosis Control Programme are presented as case studies. They show that political support does not guarantee community participation in disease control programmes and stress the importance of other determinants such as commitment to PHC, intersectoral coordination, the project approach and human resources. The relevance of the epidemiology of the disease in determining what degree of community participation will be most effective is highlighted by the case studies.

Communicable Disease Control↗
PubMed1992

Tuberculosis incidence in developing countries with high prevalence of HIV infection.

OBJECTIVE: To study the impact of the HIV epidemic on tuberculosis (TB) incidence in developing countries. DESIGN: A simple mathematical model is constructed using figures from published reports to estimate the rise of TB incidence as the HIV epidemic expands. METHOD: Two groups with different risk of developing TB are identified: individuals with dual infection of HIV and Mycobacterium tuberculosis and the rest of the population. The model is based on a combination of the incidence and the percentage of TB in these two groups. The expected rise in TB incidence and the percentage of TB cases that will be HIV-positive are plotted against the prevalence of HIV. CONCLUSIONS: Unless appropriate action is taken, TB incidence in developing countries will double as the prevalence of HIV infection reaches 13 per hundred adults.

Cohort Studies↗