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Biomedical subjects

I Martín

Publications and source records attributed to I Martín.

At least 19 recordsLinked to original sources
PubMed2006

Transcriptional profiling of cell wall protein genes in chickpea embryonic axes during germination and growth.

Cell wall hydrolases have been assumed to be involved in the regulation of seed germination, mostly through their contribution to the cell wall disassembly associated with endosperm cap weakening. In Cicer arietinum (a non-endospermic leguminosae seed), we have focused our research directly on the elongation process of the embryonic axes themselves during germination. The genes encoding cell wall proteins, previously implicated in the elongation of chickpea epicotyls, might also be involved in the expansion of embryonic axis cells, and the modulation of their expression could be part of the control of the germinative process. Thus, chickpea alpha-expansins and xyloglucan endotransglycosylase/hydrolase (XTH) acting on the cellulose/xyloglucan network seem to be involved in the elongation of both chickpea epicotyls and embryonic axes, although the products of different genes perform their actions on each organ. Among the four known cDNAs encoding chickpea alpha-expansins, Ca-EXPA1 was the only isoform highly expressed in embryonic axes during germination. In contrast to epicotyl elongation, the genes encoding cell wall beta-galactosidases, involved in pectin degradation, were not expressed during germination, suggesting no role in embryonic axis elongation, mainly due to the different metabolism of pectins during cell wall loosening in embryonic axis or epicotyl cells. The results concerning CanST-1 and -2, encoding two growth-related cell wall proteins, suggested that these genes were not involved in elongation of embryonic axes during germination. The transcription pattern of Cap28, which encodes a glutamic acid rich cell wall protein of unknown function, indicated a role in the development of the embryonic axes during germination.

Base Sequence↗
PubMed2006

Organochlorine compounds (PCBs, PCDDs and PCDFs) in seafish and seafood from the Spanish Atlantic Southwest Coast.

Concentrations and congener specific profiles of PCDD/Fs and PCBs were determined in edible fish and seafood species from the Coast of Huelva, in the Spanish southwest Atlantic coast. Five fish species, namely wegde sole (Dicologoglossa cuneata), common sole (Solea vulgaris), white seabream (Diplodus sargus), sardine (Sardina pilchardus), angler fish (Lophius piscatorius), two shellfish species (Donax trunculus and Chamelea gallina), common cuttlefish (Sepia officinalis) and prawns (Parapenaeus longirostris), frequently found and consumed in the area were analysed. Concentrations ranged from 861 to 23787pg/g wet weight for total PCBs, while 2,3,7,8-PCDD/Fs showed concentrations ranging from 0.2 to 1.18pg/g wet weight. WHO-TEQ concentrations ranged from 0.038 to 0.186pg WHO-TEQ(PCDD/Fs)/g wet weight, values well below the maximum concentrations established by the EU. When non- and mono-ortho PCBs were included the values increased to a maximum of 0.99pg WHO-TEQ(PCDD/Fs+PCBs)/g wet weight. The PCB and PCDD/F accumulation pattern found in the samples analysed showed a distribution typically reported for marine samples, and no remarkable differences were found between species. The PCBs were the ones contributing with the highest percentage to the total TEQ content in most species studied. Concerning the seafood, specially prawns and shellfish, the opposite was observed and PCDD/Fs were found to contribute with a higher percentage than PCBs. The congener specific contribution to the TEQ showed PCB 126 followed by 1,2,3,7,8-PeCDD and 2,3,4,7,8-PeCDF as the most abundant ones.

Animals↗
PubMed2005

Rotational line-integrated photoabsorption cross sections corresponding to the delta(0,0) band of NO: a molecular quantum-defect orbital procedure.

The rotational line-integrated photoabsorption cross sections corresponding to the delta(0,0) band of the nitric oxide (NO) molecule at 295 K, calculated with the molecular quantum-defect orbital methodology, are in rather good accord with the experimental measurements available in the literature. The achieved results are of straightforward use in atmospheric chemistry, such as in the assessment of the NO photodissociation rate constant, which is of great relevance for atmospheric modeling.

Journal Article↗
PubMed2005

Ground and excited states of the Rydberg radical H3O: electron propagator and quantum defect analysis.

Vertical excitation energies of the Rydberg radical H(3)O are inferred from ab initio electron propagator calculations on the electron affinities of H(3)O(+). The adiabatic ionization energy of H(3)O is evaluated with coupled-cluster calculations. These predictions provide optimal parameters for the molecular-adapted quantum defect orbital method, which is used to determine oscillator strengths. Given that the experimental spectrum of H(3)O does not seem to be available, comparisons with previous calculations are discussed. A simple model Hamiltonian, suitable for the study of bound states with arbitrarily high energies is generated by these means.

Journal Article↗
PubMed2005

Application of polymerase chain reaction to detect adulteration of sheep's milk with goats' milk.

The polymerase chain reaction has been applied for the specific detection of goats' milk in sheep's milk using primers targeting the mitochondrial 12S ribosomal RNA gene. The use of goat-specific primers yielded a 122-bp fragment from goats' milk DNA, whereas no amplification signal was obtained in sheep's, cows', and water buffaloes' milk DNA. Polymerase chain reaction analysis of raw and heat-treated milk binary mixtures of sheep/goat enabled the specific detection of goats' milk with a sensitivity threshold of 0.1%. This study demonstrates the usefulness of the proposed polymerase chain reaction assay for authentication of milk products in routine analysis.

Animals↗
PubMed2004

Weight gain and cardiovascular risk factors during smoking cessation with bupropion or nicotine.

Weight gain is frequent after smoking cessation, and may limit patient's will to quit and long-term success. Nicotine and bupropion are effective drugs for smoking withdrawal. However, their influence on weight gain, insulin resistance and other cardiovascular risk factors, as well as possible differences in obese and lean subjects, have not been fully evaluated. We randomised 25 lean and 25 obese smokers to receive either bupropion or nicotine patches. Clinical evaluation and lipid profile were performed at baseline and after treatment. Insulin resistance was also assessed at the end. Weight, BMI, waist-to-hip ratio, and diastolic blood pressure increased (p < 0.005), whereas lipid profile improved (p < 0.001) after smoking cessation independently of obesity at baseline or drug used. Obese patients had higher insulin resistance at the end (p < 0.05) regardless of drug used. Weight gain was inversely related to age (beta= - 0.125, R = 0.38, p = 0.046), and insulin resistance was related to obesity at baseline (beta = 0.85, R = 0.46, p = 0.02). In conclusion, weight gain after smoking cessation is not dependent on obesity or drug taken. A beneficial lipid profile is achieved after quitting smoking with either bupropion or nicotine patch in both obese and lean subjects.

Administration, Cutaneous↗
PubMed2003

The Ret proto-oncogene in the WAG/Rij rat strain: an animal model for inherited C-cell carcinoma?

WAG/Rij rat strain has been suggested as an animal model for the study of inherited human medullary thyroid carcinoma (MTC), due to its high incidence of spontaneous C-cell thyroid tumours. Although the role of the Ret proto-oncogene mutations, as responsible for human MTC, is well established, nothing has been published concerning this putative animal model. Based upon the previously reported rat Ret sequence, exons 10, 11, 13, 14, 15, and 16, known to carry activating mutations in humans, have been analysed in the WAG/Rij rat by PCR, single strand conformational polymorphism (SSCP) and direct sequencing. Neither the germline nor MTC samples showed any Ret sequence difference in the exons when analysed in comparison to a non-MTC-susceptible rat strain. Our results indicate that Ret exons relevant in humans are not involved in WAG/Rij rat MTC, as expected, and this questions the validity of this strain as a model for the human disease, and suggests there must be additional mechanisms for the genesis and progression of rat MTC.

Animals↗
PubMed2001

Arundifungin, a novel antifungal compound produced by fungi: biological activity and taxonomy of the producing organisms.

Echinocandins, the lipopeptide class of glucan synthase inhibitors, are an alternative to ergosterol-synthesis inhibitors to treat candidiasis and aspergillosis. Their oral absorption, however, is low and they can only be used parenterally. During a natural product screening program for novel types of glucan synthesis inhibitors with improved bioavailability, a fungal extract was found that inhibited the growth of both a wild-type Saccharomyces cerevisiae strain and the null mutant of the FKS1 gene (fks1::HIS). The mutant strain was more sensitive to growth inhibition, suggesting that the fungal extract could contain an inhibitor of glucan synthesis. A novel acidic steroid, named arundifungin, was purified from a fungal extract obtained from a liquid culture of Arthrinium arundinis collected in Costa Rica. Arundifungin caused the same pattern of hallmark morphological alterations in Aspergillus fumigatus hyphae as echinocandins, further supporting the idea that arundifungin belongs to a new class of glucan synthesis inhibitors. Moreover, its antifungal spectrum was comparable to those of echinocandins and papulacandins, preferentially inhibiting the growth of Candida and Aspergillus strains, with very poor activity against Cryptococcus. Arundifungin was also detected in nine other fungal isolates which were ecologically and taxonomically unrelated, as assessed by sequencing of the ITS1 region. Further, it was also found in two more Arthrinium spp from tropical and temperate regions, in five psychrotolerant conspecific isolates collected on Macquarie Island (South Pacific) and belonging to the Leotiales, and in two endophytes collected in central Spain (a sterile fungus belonging to the Leotiales and an undetermined coelomycete).

Antifungal Agents↗
PubMed2001

Preliminary air pollution monitoring in San Miguel, Buenos Aires.

Passive diffusion samplers were employed in San Miguel (Buenos Aires Metropolitan Area) for a preliminary air pollution monitoring. The highest loads were observed in downtown, compared with an urban background site. Total suspended particulate matter (TSPM) varied from 0.257 to 0.033 mg cm(-2) month(-1); dust was examined for particle nature and size distribution. A similar trend was observed for nitrogen dioxide (NO2) and TSPM spatial distribution, suggesting that traffic is the major pollution source. Sulphur dioxide (SO2) values were low and rather homogeneous. Levels for the investigated pollutants are below EPA's guide line values. Geographic (flat area, near to Rio de La Plata) and climatologic factors (rainfalls and variable wind directions) contribute to disperse pollutants.

Air Pollutants↗
PubMed2001

Stabilization of blood homocysteine in an epidemiological setting.

The major problem in the determination of homocysteine (Hcy), which is thought to be a risk factor in colorectal cancer, is the rise in its concentration if blood is not centrifuged immediately after collection. We assess the interference of 3-deazaadenosine (which inhibits conversion of S-adenosylhomocysteine into Hcy within the erythrocyte), using the fluorescence polarization immunoassay (FPIA) assay, the stabilizing effect of 3-deazaadenosine and the impact of temperature on Hcy stabilization. To assess interference of 3-deazaadenosine, 12 blood samples were extracted; two aliquots were obtained from each and one of them was added 3-deazaadenosine (50 micromol/l). To assess the stabilizing value of 3-deazaadenosine, as well as the effect of temperature, two blood samples were extracted from 24 volunteers. One of the tubes was immediately placed on ice and centrifuged (reference concentration). To the second tube was immediately added 3-deazaadenosine (50 micromol/l), producing six aliquots, three of which were kept at room temperature (25 degrees C) for 1, 4 and 6 hours, the other three kept at 37 degrees C. The mean values (standard deviation) obtained for methodological interference were: 7.32 (3.58) micromol/l without stabilizer, and 7.11 (3.61) micromol/l with stabilizer. There were no statistically significant differences (P = 0.104) and intraclass correlation coefficient was 0.989, suggesting no methodological interference. We did not find any significant differences regarding our reference value in the samples kept at room temperature during the interval studied. A high Pearson correlation coefficient was obtained. Nevertheless, in those samples kept at 37 degrees C, a slight increase was observed in the 4-hour period (P = 0.009). The addition of 3-deazaadenosine may avoid problems in the critical pre-analytical phase in the Hcy measurement. There is no interference with the FPIA assay, nor any dilution effect, and new reference values are not necessary.

Drug Interactions↗
PubMed2000

Inhibitors of farnesylation of Ras from a microbial natural products screening program.

Mutant ras oncogenes are associated with various human tumors such as pancreas, colon, lung, thyroid, bladder and several types of leukemia. Prenylation of Ras proteins plays a major role in cell proliferation of both normal and cancerous cells. Normal and oncogenic Ras proteins are posttranslationally modified by a farnesyl group that promotes membrane binding. Inhibitors of farnesyl protein transferase (FPTase), the enzyme that catalyzes the prenylation of Ras proteins, inhibit growth of tumor cells. In an effort to identify structurally diverse and unique inhibitors of FPTase, a program devoted to screening of natural products was initiated. This effort led to the identification of 10 different families of compounds, all of which selectively inhibit FPTase with a variety of mechanisms that are reviewed in this manuscript. These compounds originated from the fermentations of a number of microorganisms, either actinomycetes or fungi, isolated from different substrates collected in tropical and temperate areas. A chemotaxonomic discussion on the distribution of each compound among single or different types of microorganisms, either phylogenetically related or unrelated species, is included.

Journal Article↗
PubMed1999

Living with Machado-Joseph disease in a small rural community of the Tagus valley.

OBJECTIVES: In the context of our national program of predictive testing for Machado-Joseph disease (MJD), we have studied in a small rural community (1) discourses about the illness by individuals at risk and patients, and (2) how individuals at risk and patients plan to cope with the familial illness. METHODS: We used qualitative methods, beginning with a group interview of individuals at risk, and followed by in-depth interviews (about 1 hour long) of at-risk and affected individuals, in their homes. The latter interviews were subjected to a content analysis. RESULTS: The coexistence of two contradictory discourses about MJD (a scientific and a folk one) was found consistently among all individuals. The main metaphor was that of the 'drunkard'. Knowledge about a precise diagnosis of their disease produced relief and hope, because it provided evidence that affected individuals were not drunkards. CONCLUSIONS: The understanding of beliefs about the disease and its social representation is essential in planning effective genetic and psychological counseling.

Journal Article↗
PubMed1998

Physical mapping of the conjugative plasmid pMB1-1 of Enterococcus faecalis.

The sexpheromone system of Enterococcus faecalis is a form of bacterial conjugation that plays an important role in the horizontal dissemination of genes. The ecological significance of 'sexual' plasmids is to permit a rapid mobilization of genes of interest for the species (e.g. those encoding haemolysins, bacteriocins or antibiotic resistance). The physical mapping of pMB1-1, a conjugative plasmid of Ent. faecalis that responds to cCF10 pheromone, has been undertaken. By means of hybridization with conserved sequences of pCF10 plasmid, the regions harbouring the genes responsible for the pheromone inhibitor and the aggregation and exclusion proteins of this plasmid have been identified. The results demonstrated that plasmids pMB1-1 and pCF10 only show homology in the region involved in the conjugative response, suggesting that this region may be transferred in an independent way to that of the rest of the plasmid.

Blotting, Southern↗
PubMed1997

Growth and differentiation factors inhibit the migratory phenotype of cultured neonatal rat hepatocytes induced by HGF/SF.

Previous studies have demonstrated that neonatal rat hepatocytes cultured in a serum-free medium adopt a fibroblast-like morphology and form a well-developed vimentin network. By immunoblotting, phase-contrast microscopy, and immunolocalization studies we report here that hepatocyte growth factor (HGF) induces a pronounced migratory/scatter phenotype in neonatal hepatocytes in primary culture. These fibroblast-like cells are highly elongated and adopt a pronounced spindle shape in the presence of this growth factor. Most of them coexpress vimentin and cytokeratin intermediate filaments. Both EGF and TGF-beta1 also induced vimentin expression in cytokeratin-positive cells but this effect was not correlated with a change of epithelial phenotype. Only in DMSO-supplemented cultures was vimentin expression of hepatocytes inhibited and no coexpression was observed in the presence of this factor. Remarkably, the effect induced by HGF was totally inhibited when DMSO, TGF-beta1, or EGF was added to HGF-supplemented cultures. Epithelial sheets of well-defined hepatocytes were observed with these combinations although the complete epithelial morphology was achieved by combining DMSO with a growth factor. Taken together these results suggest that growth and differentiation factors modulate the migratory effect of HGF/SF in hepatocytes.

Animals↗