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Biomedical subjects

A M Rodríguez

Publications and source records attributed to A M Rodríguez.

At least 19 recordsLinked to original sources
PubMed2002

Preparation of new monoanionic "scorpionate" ligands: synthesis and structural characterization of titanium(IV) complexes bearing this class of ligand.

The preparation of new "scorpionate" ligands in the form of the lithium derivatives [(Li(bdmpzdta)(H(2)O))(4)] (1) [bdmpzdta = bis(3,5-dimethylpyrazol-1-yl)dithioacetate], [Li(bdphpza)(H(2)O)(THF)] (2) [bdphpza = bis(3,5-diphenylpyrazol-1-yl)acetate], and [Li(bdphpzdta)(H(2)O)(THF)] (3) [bdphpzdta = bis(3,5-diphenylpyrazol-1-yl)dithioacetate] has been carried out. Furthermore, a series of titanium complexes has been prepared by reaction of TiCl(4)(THF)(2) with the lithium reagents [(Li(bdmpza)(H(2)O))(4)] (4) [bdmpza = bis(3,5-dimethylpyrazol-1-yl)acetate] and 1. Under the appropriate experimental conditions neutral complexes, namely [TiCl(3)(kappa(3)-bdmpza)] (5), [TiCl(3)(kappa(3)-bdmpzdta)] (6), and [TiCl(2)(kappa(2)-bdmpzdta)(2)] (7), and cationic complexes, namely [TiCl(2)(THF)(kappa(3)-bdmpza)]Cl (8) and [TiCl(2)(THF)(kappa(3)-bdmpzdta)]Cl (9), were isolated. Complexes 8 and 9 undergo an interesting nucleophilic THF ring-opening reaction to give the corresponding alkoxide-containing species [TiCl(2)(kappa(3)-bdmpza)(O(CH(2))(4)Cl)] (10) and [TiCl(2)(kappa(3)-bdmpzdta)(O(CH(2))(4)Cl)] (11). A family of alkoxide-containing complexes of general formulas [TiCl(2)(kappa(3)-bdmpza)(OR)] [R = Me (12); R = Et (14); R = (i)Pr (16); R = (t)Bu (18)] and [TiCl(2)(kappa(3)-bdmpzdta)(OR)] [R = Me (13); R = Et (15); R = (i)Pr (17)] was also prepared. The structures of these complexes have been determined by spectroscopic methods, and in addition, the X-ray crystal structures of 3, 7, 10, and 11 were also established.

Journal Article↗
PubMed2001

In vitro antifungal evaluation and structure-activity relationships of a new series of chalcone derivatives and synthetic analogues, with inhibitory properties against polymers of the fungal cell wall.

Here we report the synthesis, in vitro antifungal evaluation and SAR study of 41 chalcones and analogues. In addition, all active structures were tested for their capacity of inhibiting Saccharomyces cerevisiae beta(1,3)-glucan synthase and chitin synthase, enzymes that catalyze the synthesis of the major polymers of the fungal cell wall.

Antifungal Agents↗
PubMed2001

Sex-dependent dietary obesity, induction of UCPs, and leptin expression in rat adipose tissues.

OBJECTIVE: The aim of this study was to determine the sex-dependent differences in the response of key parameters involved in thermogenesis and control of body weight in brown adipose tissue (BAT) and white adipose tissue (WAT) in postcafeteria-fed rats, a model of dietary obesity. RESEARCH METHODS AND PROCEDURES: BAT and WAT were obtained from male and female control and postcafeteria-fed Wistar rats. Postcafeteria-fed rats were initially fed with cafeteria diet from day 10 of life until day 110 (cafeteria period) and with standard chow diet from then until day 180 of life (postcafeteria period). Body mass and energy intake were evaluated. Biometric parameters were analyzed in interscapular BAT (IBAT). Levels of uncoupling protein 1 (UCP1), alpha(2)-adrenergic receptor (AR), and beta(3)-AR proteins and UCP1, UCP2, UCP3, beta(3)-AR, and leptin mRNAs, in IBAT or WAT, were studied by Western blot and Northern blot analyses, respectively. RESULTS: Rats attained 59% (females) and 39% (males) increase in body weight at the end of the cafeteria period. During the postcafeteria period, the rats showed a loss of body weight, which was higher in females. Postcafeteria-fed female rats also presented higher activation of thermogenic parameters in IBAT, including UCP1, UCP2, and UCP3 mRNAs. Female control rats showed lower levels of both alpha 2 and beta(3)-ARs in BAT compared with male rats, but these levels in postcafeteria-fed female and male rats were the same, because males tended to down-regulate them. Levels of leptin mRNA in response to the postcafeteria state depended on gender and the specific WAT depot studied. DISCUSSION: It is suggested that in postcafeteria-fed female rats, BAT thermogenic capacity becomes more efficiently activated than in males. Female rats also showed a bigger weight loss. The parallel regulation of the levels of UCP2 and UCP3 mRNAs, with respect to UCP1 mRNA, with higher activation in female postcafeteria-fed rats, suggests a possible role of both UCP2 and UCP3 in the regulation of energy expenditure and in the control of body weight. The distinct responses to overweight of alpha 2 and beta(3)-ARs--which were sex dependent--and leptin mRNA--which depended on both sex and WAT depot--also support the different response of thermogenesis-related parameters between overweight males and females.

Adipose Tissue↗
PubMed2001

Intralesional isotype profiles in human localized cutaneous leishmaniasis lesions.

This immunocytochemical study evaluates the presence of IgG1-4, IgA and IgE immunoglobulins in active lesions of 25 localized cutaneous leishmaniasis patients from three bioclimatic areas (Awa, Afa and Bsha) in Mérida State, Venezuela. All immunoglobulin isotypes except IgE were detected, with variable intensity, in one or more of the epidermal or dermal components of skin lesions. IgG1 and IgG2 were detected significantly more frequently than IgG3, IgG4 and IgA. The ranking of the isotypes according to frequency of detection was the same in all areas: IgG1 = IgG2 > IgG3 = IgG4 = IgA, but considered as whole, all isotypes were detected significantly more frequently in patients from the Awa area than in those from the Bsha area. The predominant expression of isotypes IgG1 and IgG2 suggests a preferential Th1 like immune response. Anti-Leishmania immunoserum stained only parasites and their debris, suggesting that most of the immunostaining was nonspecific.

Adolescent↗
PubMed2000

Mitochondrial or cytosolic catalase reverses the MnSOD-dependent inhibition of proliferation by enhancing respiratory chain activity, net ATP production, and decreasing the steady state levels of H(2)O(2).

Manganese superoxide dismutase (MnSOD) overexpression has been shown to reverse the malignant phenotype in a variety of tumor cell lines. The inhibition of proliferation and reversal of the malignant phenotype has been attributed to an increase in H(2)O(2) production as a result of the dismutation reaction. However, direct evidence in support of this hypothesis has not been forthcoming. To evaluate the contribution of H(2)O(2) in the regulation of cell growth in response to MnSOD overexpression, control and MnSOD-overexpressing HT-1080 fibrosarcoma cells were transfected with constructs that direct catalase to either the mitochondrial or cytosolic compartments. Overexpression of catalase in either compartment reversed the proliferative and clonogenic inhibition associated with MnSOD overexpression, blocked the increase in the steady state levels of H(2)O(2) as measured by flow cytometric analysis of 2', 7'-dichlorofluorescein diacetate, and increased protection from the cytotoxicity of H(2)O(2). In addition, mitochondrial or cytosolic catalase enhances respiration through complex I and II in both control and MnSOD overexpressing cell lines and reverses a MnSOD-dependent decrease in net ATP production. Thus, catalase reverses the proliferative inhibition associated with MnSOD overexpression and may also play an important role in metabolic regulation.

Adenosine Triphosphate↗
PubMed2000

Pd(II) complexes with polydentate nitrogen ligands. Molecular recognition and dynamic behavior involving Pd-N bond rupture. X-ray molecular structures of [[Pd(C6HF4)2](bpzpm)] and [[Pd(eta 3-C4H7)]2(bpzpm)] (CF3SO3)2 [bpzpm = 4,6-bis(pyrazol-1-yl)pyrimidine].

The ligands 4,6-bis(pyrazol-1-yl)pyrimidine (bpzpm) and 4,6-bis(4-methylpyrazol-1-yl)pyrimidine (Me-bpzpm) were synthesized and their reactions with some palladium derivatives explored. Mononuclear or dinuclear neutral or cationic complexes were obtained by reaction of the ligands with 1 or 2 equiv of Pd(C6XF4)2(cod) (cod = 1,5-cyclooctadiene; X = F, H) or the palladium fragment [Pd(eta 3-2-Me-C3H4)(S)2]+ (S = acetone). The reaction of the dinuclear derivatives with 1 equiv of the respective free ligand immediately led to the regeneration of the mononuclear complexes. Except in the case of the synthesis of [[Pd(C6HF4)2][Pd(C6F5)2](bpzpm)], where two similar metallic groups are present, all attempts to obtain dinuclear asymmetric complexes with two different palladium fragments failed. Instead, the dinuclear symmetric complexes were formed. This result could be considered as an example of molecular recognition with the ligand acting as a ditopic receptor. This behavior is comparable to chemical symbiosis but in this case applied to the ligand rather than to the metal center as occurs normally. The polyfluorophenyl rings are situated on average in a perpendicular orientation with respect to the coordination plane. Their restricted rotation results in several atropoisomers for the complexes with m-C6HF4. Different cross-reaction experiments were carried out, and these showed the mobility of the metallic fragments, with the more difficult process being that involving the more strongly bonded polyfluorophenyl palladium groups. By means of 1H NMR variable temperature studies, the interconversion of the two isomers of [[Pd(eta 3-C4H7)]2-(bpzpm)]Tf2 (Tf = CF3SO3) was analyzed. In the case of [[Pd(eta 3-C4H7)](bpzpm)]Tf the existence of two processes, an intramolecular apparent allyl rotation and an intermolecular exchange of the allylpalladium fragments, has been demonstrated. Different delta Gc++ values at the coalescence temperatures have also been determined. An X-ray single-crystal analysis was carried out on [[Pd(eta 3-C4H7)]2(bpzpm)]Tf2, which crystallizes in the monoclinic system, space group I2/m, with a = 9.368(2), b = 16.191(3), c = 20.228(6) A, beta = 101.26(3), and Z = 4. Compound [[Pd(C6HF4)2](bpzpm)] crystallized in the triclinic system, space group P1, with a = 8.845(6), b = 12.6609(9), c = 12.826(3) A, alpha = 88.45(2), beta = 74.36(3), gamma = 89.32(2), and Z = 2.

Journal Article↗
PubMed1999

Intraoral mandibular distraction osteogenesis.

During recent years, distraction osteogenesis has gained in popularity for the treatment of various bone deficiencies either in the vertical, transverse, or anteroposterior dimension. Distraction osteogenesis has been shown to be an effective technique for mandibular widening and lengthening where traditional orthognathic surgery has important limitations. The intraoral approach to these procedures prevents damage to the inferior alveolar nerve and the developing dental follicles, and eliminates hypertrophic facial scars. Intraoral distraction osteogenesis also avoids donor-site morbidity, and minimizes the need for blood transfusion or prolonged fixation. This intraoral application provides for enhanced patient acceptance and reduces the potentially negative psychosocial effects of wearing an extraoral distraction appliance.

Clinical Protocols↗
PubMed1999

In vitro evaluation of antifungal properties of phenylpropanoids and related compounds acting against dermatophytes.

Thirty-four arylpropanoids and related compounds were evaluated in vitro for antifungal properties. Among them, 22 phenyl-, 4 naphthyl-, and 4 phenanthrylpropanoids; naphthalene; phenanthrene; and 2-chloro-1-hexyl-1-propanone were tested against dermatophytes by the agar dilution method. alpha-Halopropiophenones exhibited a broad spectrum of activities against Microsporum canis, Microsporum gypseum, Trichophyton mentagrophytes, Trichophyton rubrum, and Epidermophyton floccosum, with MIC values between 0.5 and >50 microg/mL. Keto, alcohol, and alpha-haloketo propyl derivatives of naphthalene and phenanthrene also showed very good activity against all dermatophytes tested, clearly showing that in these series, a halogen atom is not necessary for activity. Phenanthryl derivatives were more active (MICs, 3-20 microg/mL) than naphthyl ones (MICs, 3-50 microg/mL). A structure-activity relationship study was carried out and aided in establishing the structural requirements of arylpropanoids for antifungal activities. Because dermatophytes are a group of fungi that characteristically infect the keratinized areas of the body, these new series of antifungal compounds open the possibility of discovering new topical antifungal drugs for the treatment of dermatomycoses, which are frequently very difficult to eradicate.

Antifungal Agents↗
PubMed1998

Automated peritoneal dialysis: a Spanish multicentre study.

BACKGROUND: A prospective sequential study on continuous ambulatory peritoneal dialysis (CAPD) and three techniques of automated peritoneal dialysis (APD) was conducted to assess peritoneal clearances, the influence of peritoneal permeability on nocturnal APD clearances and the suitability of the peritoneal equilibration test (PET) for predicting clearances on APD. METHODS: After performing a PET, a series of clinical, biochemical and dialysis adequacy markers were evaluated after 2 months on CAPD, continuous cycling peritoneal dialysis (CCPD) and tidal volume peritoneal dialysis (TPD) with 50% and 25% tidal volumes. Forty five patients participated and 33 completed the study. RESULTS: Serum urea and creatinine decreased significantly whereas haemoglobin and glucose increased. Mean peritoneal urea clearance (1/week) was 55.40+/-8.76 on CAPD, 74.82+/-12.62 on CCPD, 69.20+/-14.63 on TPD (tidal 50%) and 66.89+/-13.23 on TPD (tidal 25%); mean creatinine clearance (1/week/1.73 m2) was 42.80 +/- 9.95, 52.19 +/- 11.11, 51.31 +/- 13.3 and 49.17 +/- 11.83, respectively. Both clearances were significantly lower on CAPD than on APD (P<0.001). CCPD was the automated technique that provided the best nocturnal urea clearance (P<0.01). Nocturnal creatinine clearance did not show significant differences between CCPD and TPD (tidal 50%), being better with both techniques than with TPD (tidal 25%). There were statistically significant differences between nocturnal dialysate to plasma (D/P) ratios and those corresponding to the nearest times in the PET. The urea D/P ratio at 180 min and the creatinine D/P ratio at 240 min of the PET were the parameters that better estimated nocturnal clearances on APD. CONCLUSIONS: This study confirms that TPD does not improve the results of CCPD. Significant differences between D/P ratios during actual nocturnal cycles and PETs were observed.

Aged↗
PubMed1997

Structure-cytoprotective activity relationship of simple molecules containing an alpha,beta-unsaturated carbonyl system.

In previous reports we attributed the cytoprotective activity of several sesquiterpene lactones to the presence of a nonhindered electrophilic acceptor in their structure. We suggested that the mechanism of protection would be, at least in part, mediated through a reaction between the electrophilic acceptor and the sulfhydryl-containing groups of the mucosa. We report here the gastric cytoprotective effect of simple molecules containing an alpha, beta-unsaturated carbonyl group. In the present paper, we undertake the study of molecular accessibility and molecular shape, in addition to conformational, electronic, and steric factors. Our results helped to establish two important facts connecting chemical structure with cytoprotective effect. Firstly, an adequate molecular accessibility appears to be necessary to produce the biological response, and secondly, the alpha,beta-unsaturated carbonyl system has to be included in a cyclic structure or, at least, in the proximity of a cyclic system.

4-Butyrolactone↗
PubMed1995

[Characteristics of AIDS cases detected at a prison in Barcelona (1991-1993)].

OBJECTIVE: To describe the cases of AIDS detected in a Barcelona prison. DESIGN: A prospective study. SETTING: A penitentiary for men in Barcelona. PATIENTS: All those inmates who had AIDS or were diagnosed with the illness during their stay in prison during the 36 months between 1/1/1991 and 31/12/93. RESULTS: 220 cases of AIDS (91.7% PVDA), 60% of which were diagnosed in prison. The PVDA were younger (p < 0.0001). There were a greater number of Spaniards among the UDVP (p < 0.01) and among those with tattoos (p < 0.001). The first manifestation of the disease in 53% of the cases was extrapulmonary Tuberculosis. CONCLUSIONS: Prisons are key places in the prevention and monitoring of HIV infection. The use of care programmes, including maintenance programmes using Methadone, for drug-dependent patients are recommended. The continuation of programmes tracking Tuberculosis, the main illness related to HIV infection in prison, is also recommended.

Acquired Immunodeficiency Syndrome↗
PubMed1995

A second ABC transporter is involved in oleandomycin resistance and its secretion by Streptomyces antibioticus.

A 3.2 kb Sstl-Sphl DNA fragment of Streptomyces antibioticus, an oleandomycin producer, conferring resistance to oleandomycin was sequenced and found to contain an open reading frame of 1710 bp (oleB). Its deduced gene product (OleB) showed a high degree of similarity with other proteins belonging to the ABC-transporter superfamily including the gene product of another oleandomycin-resistance gene (OleC). The OleB protein contains two ATP-binding domains, each of approximately 200 amino acids in length, and no hydrophobic transmembrane regions. Functional analysis of the oleB gene was carried out by deleting specific regions of the gene and assaying for oleandomycin resistance. These experiments showed that either the first or the second half of the gene containing only one ATP-binding domain was sufficient to confer resistance to oleandomycin. The gene oleB was expressed in Escherichia coli fused to a maltose-binding protein (MBP) using the pMal-c2 vector. The MBP-OleB hybrid protein was purified by affinity chromatography on an amylose resin and polyclonal antibodies were raised against the fusion protein. These were used to monitor the biosynthesis and physical location of OleB during growth. By Western analysis, the OleB protein was detected both in the soluble and in the membrane fraction and its synthesis paralleled oleandomycin biosynthesis. It was also shown that a Streptomyces albus strain, containing both a glycosyltransferase (OleD) able to inactivate oleandomycin and the OleB protein, was capable of glycosylating oleandomycin and secreting the inactive glycosylated molecule. It is proposed that OleB constitutes the secretion system by which oleandomycin or its inactive glycosylated form could be secreted by S. antibioticus.

ATP-Binding Cassette Transporters↗
PubMed1994

Characterisation of a Streptomyces antibioticus gene encoding a type I polyketide synthase which has an unusual coding sequence.

A gene (ORFB) from Streptomyces antibioticus (an oleandomycin producer) encoding a large, multifunctional polyketide synthase (PKS) was cloned and sequenced. Its product shows an internal duplication and a close similarity to the third subunit of the PKS involved in erythromycin biosynthesis by Saccharopolyspora erythraea, showing the equivalent nine active site domains in the same order along the polypeptide. An unusual feature of this ORF is the GC content of most of the sequence, which is surprisingly low, for a Streptomyces gene; the large number of codons with T in the third position is particularly striking. The last 800 bp of the gene stand out as being normal in their GC content, this region corresponding almost exactly to the thioesterase domain of the gene and suggesting that this domain was a late addition to the PKS. Based on the high degree of similarity between the ORFB product and the third subunit of the erythromycin PKS and the occurrence nearby of a gene conferring oleandomycin resistance, it is possible that this gene might be involved in the biosynthesis of the oleandomycin lactone ring.

Amino Acid Sequence↗
PubMed1994

Comparison between the effects of VIP and the novel peptide PACAP on the exocrine pancreatic secretion of the rat.

The effect of intravenous infusion of pituitary adenylate cyclase-activating peptide (PACAP) 27, a novel regulatory peptide that shows a close structural and chemical similarity to vasoactive intestinal peptide (VIP), on the rat exocrine pancreatic secretion was studied. PACAP and VIP stimulated the flow rate of exocrine pancreatic secretion (p < 0.05). However, protein output and amylase secretion were mainly stimulated by PACAP. Intravenous infusion of VIP increased the plasma levels of secretin (p < 0.05). On the other hand, PACAP released neither secretin nor VIP. Our results show: (a) both PACAP and VIP stimulate exocrine pancreatic secretion, (b) PACAP stimulation of pancreatic amylase and protein secretion is greater than that induced by VIP, and (c) PACAP probably exerts a direct effect on exocrine pancreas whereas some of the actions of VIP might be mediated by secretin.

Amylases↗
PubMed1993

Thermotherapy v. antimonials: what happens after the healing of cutaneous leishmaniasis lesions?

The long-term effects of meglumine antimoniate (chemotherapy) or exposure to an environmental temperature of 37 degrees C (thermotherapy) on the evolution of Leishmania mexicana infections and on the response to challenge infections six months after treatment were compared in susceptible (BALB/c) and partially resistant (C57BL/6) mice. Thermotherapy was better than chemotherapy in that it healed lesions quicker and prevented relapses in the partially resistant mice during the observation period. However, both treatments appeared equally effective in terms of clinical cure. Neither treatment cleared all parasites from the hosts and both impaired the hosts' immune response to a challenge infection. The results indicate that specific immunity fades with time post-infection and that the persistence of the parasite in a clinically cured host does not maintain protective immunity against challenge infections.

Animals↗
PubMed1993

Streptomyces antibioticus contains at least three oleandomycin-resistance determinants, one of which shows similarity with proteins of the ABC-transporter superfamily.

Three different DNA fragments of an oleandomycin producer, Streptomyces antibioticus, conferring oleandomycin resistance were cloned in plasmid pIJ702 and expressed in Streptomyces lividans and in Streptomyces albus. These oleandomycin resistance determinants were designated as oleA (pOR400), oleB (pOR501) and oleC (pOR800). oleA and oleC are closely linked in the chromosome as they were both obtained together in two cosmid clones that were isolated from a genomic library. Sequencing of the oleC resistance determinant revealed four complete open reading frames (ORFs) and the C-terminal end of a fifth. The functions of orf1 and orf2 are unknown since they did not show significant similarity with other sequences in the data bases. The orf3 gene product has similarity with some proteins involved in iron and vitamin B12 uptake in bacteria. The orf4 gene product had a hydrophilic profile and showed important similarity with proteins containing typical ATP-binding domains characteristic of the ABC-transporter superfamily and involved in membrane transport and, particularly, with several genes conferring resistance to various macrolide antibiotics and anticancer drugs. The last gene, orf5, is translationally coupled to orf4 and codes for a hydrophobic polypeptide containing several transmembrane domains characteristic of integral membrane proteins. Subcloning and deletion experiments limited the resistance determinant to a 0.9 kb PstI-SphI fragment and only orf4 is included in this fragment. These results suggest that resistance to oleandomycin conferred by oleC (orf4) is probably due to an efflux transport system of the ABC-transporter superfamily.

Adenosine Triphosphate↗
PubMed1992

Structure-activity relationship in the gastric cytoprotective effect of several sesquiterpene lactones.

The structural requirements for the gastric cytoprotective activity of several sesquiterpene lactones are reported. A theoretical-experimental study on the potentially active centers is carried out. The biological evaluation of reduced analogues and the simulation of the molecular interactions between these compounds and an endogenous cysteine residue suggest that the presence of a non sterically hindered Michael acceptor seems to be an essential structural requirement for the cytoprotective activity in this family of compounds. This observation suggests that cytoprotection is mediated through a Michael reaction between the sulfhydryl-containing peptides of the mucosa and Michael acceptors present in the molecules under study. This mechanism of action is in addition to and distinct from the one proposed in our previous paper, namely, that these sesquiterpenes stimulate endogenous synthesis of prostaglandins.

Lactones↗