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Biomedical subjects

M C Barbero

Publications and source records attributed to M C Barbero.

15 recordsLinked to original sources
PubMed2003

DNA polymorphisms detect ancient barriers to gene flow in Basques.

This work features the first district-by-district analysis of all provinces in the Iberian Peninsula with an autochthonous Basque population, and indicates the existence of genetic heterogeneity. The populations cluster in three groups arising from processes of genetic drift which probably occurred in pre-Mesolithic times, and were probably those which repopulated the southern areas of the Basque Country after the Last Glacial Maximum. It seems that from that period onwards, the population settled in three major groups (West Basques, Central Basques, and East Basques), along geographical axes which appear substantial in the maintaining of each population unit. This genetic structure is probably reflected in other aspects such as the existence of ancient tribes and the dialects of the Basque language, the boundaries of which may be related at origin and which are quite similar to those detected in this work. Our results indicate that the populations of the Basque Country are genetically close to other neighboring populations, such as that of Aragon, which may indicate an outgoing gene flow from the Basque area down the River Ebro towards the Mediterranean seaboard. While our short tandem repeat data suggest that population structure within the Basques dates back to the Mesolithic, our findings are also consistent with the hypothesis that patterns of modern European genetic diversity have been shaped mainly during the Neolithic.

DNA↗
PubMed1999

Analysis of 6 short tandem repeat loci in Navarre (northern Spain).

A genetic study was performed on a sample of 146 autochthonous individuals from the province of Navarre (northern Spain) to test for 6 STR systems: CSF1PO, TPOX, TH01, F13A1, FES/FPS, and VWA31/A. The Navarre population has a series of allele frequencies that are at the extreme end of the European range of variation and that are in most cases similar to those found in the Basque population of the provinces of Alava, Biscay, and Guipuzcoa. This similarity is corroborated by correspondence analysis, in which the population of Navarre is at one end of the first axis with the Basque sample close to it and the remaining European populations far removed. In tree-type representations the Navarre population is grouped with the Basque series at 1 end. Even so, the comparison of allele frequency distributions by the chi-square heterogeneity test indicates that these 2 groups are statistically different. Our results together with the cultural relationship that exists between all the Basque-speaking provinces and the genetic heterogeneity described in earlier studies between the Basque provinces of Alava, Biscay, and Guipuzcoa (Aguirre et al. 1989; Manzano, Orue et al. 1996; Manzano, Aguirre et al. 1996) lead us to believe that the Navarre population lies within the heterogeneous Basque genetic map.

Chi-Square Distribution↗
PubMed1991

Correlation between secretion pattern and metastatic potential from drug-treated 3LL tumor cell line.

In the present study, we described the effects of three different drugs, A23187 calcium ionophore (A23187), indomethacin (IND) and phorbol myristate acetate (PMA), on the secretion pattern and the metastatic potential in the low metastatic 3LL tumor cell line. The results evidence that a low molecular weight protein fraction is always secreted in an higher amount in drug treated cells than in untreated cells independently of the drug used. In addition to their effects on secretion pattern, the three drugs assayed enhance noticeably the metastatic rate in vivo of the 3LL cells. The data confirm our earlier observations showing that our high performance gel permeation chromatography (HPGPC) method is suitable for discriminating even between cells with a different degree (low and high) of metastatic potential by its chromatographic secretion pattern and that alterations in the secretion pattern from treated cells are related with changes in the degree of metastatic potential of these cells.

Animals↗
PubMed1991

Morphological and functional changes in Lewis lung carcinoma cells after treatment with A23187 calcium ionophore.

Cultured Lewis Lung carcinoma cells (3LL) treated with A23187 calcium ionophore were studied by transmission electron microscopy and HPLC analysis. Results showed that A23187 calcium ionophore induces on osmiophilic inclusion bodies of 3LL cells similar process of lamellar bodies formation to those reported in the development of the osmiophilic inclusions bodies within the granular pneumocyte of normal lungs. HPLC analysis shows that calcium ionophore generates quantitative changes in the 3LL cytoplasmic protein content expressed by an increase of 18-22 kDa and 4-9 kDa proteins.

Animals↗
PubMed1989

HPLC analysis of supernatant soluble factors from tumor cell variants with defined metastatic status.

In the present study, we report a simple and sensitive procedure to study supernatant soluble factors of short time cultured cells by high performance gel permeation chromatography (HPGPC). This procedure enables a direct analysis with no preparatory procedures prior to application in the chromatographic column and eliminates tedious and often low reproducible techniques, required during conventional assay of culture medium. In addition, we show that HPGPC analysis is suitable for discriminating between two variants of a rhabdomyosarcoma with different metastatic potential, while two distinct cell lines (3LL carcinoma and B16F10 melanoma), which do not differ in their metastatic potential, do not present noticeable qualitative differences in their chromatographic secretion pattern.

Animals↗
PubMed1986

Membrane-surfactant interactions. The role of surfactant in mitochondrial complex III-phospholipid-Triton X-100 mixed micelles.

Complex III (ubiquinol-cytochrome c reductase) was purified from beef heart mitochondria in the form of protein-phospholipid-Triton X-100 mixed micelles (about 1:80:100 molar ratio). Detergent may be totally removed by sucrose density gradient centrifugation, and the resulting lipoprotein complexes retain full enzyme activity. In order to understand the role of surfactant in the mixed micelles, and the interaction of Triton X-100 with integral membrane proteins and phospholipid bilayers, both the protein-lipid-surfactant mixed micelles and the detergent-free lipoprotein system were examined from the point of view of particle size and ultrastructure, enzyme activity, tryptophan fluorescence quenching, 31P NMR, and Fourier transform infrared spectroscopy. The NMR and IR spectroscopic studies show that surfactant withdrawal induces a profound change in phospholipid architecture, from a micellar to a lamellar-like phase. However, electron microscopic observations fail to reveal the existence of lipid bilayers in the absence of detergent. We suggest that, under these conditions, the lipid:protein molar ratio (80:1) is too low to permit the formation of lipid bilayer planes, but the relative orientation and mobility of phospholipids with respect to proteins is similar to that of the lamellar phase. Protein conformational changes are also detected as a consequence of surfactant removal. Fourier transform infrared spectroscopy indicates an increase of peptide beta-structure in the absence of Triton X-100; changes in the amide II/amide I intensity ratio are also detected, although the precise meaning of these observations is unclear. Tryptophanyl fluorescence quenching by acrylamide shows that a significant fraction of the Trp residues sensing the quencher become less readily available to it in the absence of surfactant. The temperature dependence of enzyme activity (expressed in the form of Arrhenius plots) is also different in the presence and absence of detergent. The effects of surfactant removal do not appear to be readily reversible upon readdition of Triton X-100.

Acrylamide↗
PubMed1984

Physiological state of submitochondrial particles and their susceptibility to Triton X-100.

The solubilizing effect of Triton X-100 on beef heart submitochondrial particles (ETPH) has been studied under various physiological conditions. Coupled, uncoupled and azide-inhibited ETPH particles have been studied. Quantitative and qualitative differences are found in the proteins solubilized by the detergent from ETPH particles under the various conditions tested.

Animals↗
PubMed1984

Effect of the nonionic detergent Triton X-100 on mitochondrial succinate-oxidizing enzymes.

Specific activities of succinate:coenzyme Q reductase, ubiquinone:cytochrome c reductase, cytochrome oxidase, succinate:cytochrome c reductase, succinate oxidase, and ubiquinol oxidase have been measured in rat liver mitochondria in the presence of Triton X-100. The last three activities are much more sensitive to Triton X-100 than the first ones; the data suggest that the electron transport chain components cannot react with each other in the presence of the detergent. At least in the case of succinate:cytochrome c reductase, reconstitution of the detergent-treated membranes with externally added phospholipids reverses the inhibition produced by Triton X-100. These results support the idea that the respiratory chain components diffuse at random in the plane of the inner mitochondrial membrane; the main effect of the detergent would be to impair lateral diffusion by decreasing the area of lipid bilayer. When detergent-treated mitochondrial suspensions are centrifuged in order to separate the solubilized from the particulate material, only the first three enzyme activities mentioned above are found in the supernatants. After centrifugation, a latent ubiquinol:cytochrome c oxidase activity becomes apparent, whereas the same centrifugation process produces inhibition of cytochrome c oxidase in the presence of certain Triton X-100 concentrations. These effects could be due either to a selective solubilization of regulatory or catalytic subunits or to a conformational change of the enzyme-detergent complex.

Animals↗
PubMed1983

The impairment of mitochondrial function by Triton X-100. A study of mitochondrial respiration and energy-dependent swelling.

Coupled and uncoupled respiration, and energy-dependent phosphate swelling have been studied in rat liver mitochondria in the presence of various concentration of Triton X-100. Detergent concentrations up to 10(-5) M do not affect any of the processes under study. At 10(-5) M, Triton X-100 produces a slight decrease of coupled respiration and a considerable inhibition of mersalyl-induced shrinking in swollen mitochondria. Increasing the surfactant concentration to 10(-4), coupled as well as uncoupled O2 consumption is decreased, succinate-dependent phosphate swelling is inhibited and an energy-dependent phosphate swelling in the absence of valinomycin is observed. At 2 X 10(-4) M. Triton X-100, ATP- dependent phosphate swelling is abolished, and passive swelling may be induced by various ions. Higher detergent concentrations do not allow observation of any of these events. On the basis of these results, a model of membrane-detergent interaction is proposed.

Animals↗
PubMed1982

Fractionation of rat liver mitochondrial components after short treatments with Triton X-100.

1. When rat liver mitochondria are treated with the non-ionic detergent Triton X-100, the solubilizing effects of the latter are already maximal after a few seconds. 2. We have developed a filtration technique that allows a fast separation of the solubilized and non-solubilized fractions. By means of this technique, we have been able to show differences in the solubilizing effect of Triton X-100 according to the physiological state of mitochondria. 3. In addition, the filtrate may be subjected to further fractionation by ultracentrifugation, by which two filtrate subfractions, supernatant and pellet, may be obtained. 4. Filtrates, supernatants and pellets differ from each other, and from intact mitochondria, in phospholipid and polypeptide composition, and possess a characteristic distribution of enzyme activities; they are also different from the ultrastructural point of view. 5. It is concluded that the combined techniques of short detergent treatments and fast filtration are useful in structural and functional studies of mitochondria and in the selective solubilization of mitochondrial components.

Animals↗
PubMedDate not supplied

Data on six short-tandem repeat polymorphisms in an autochthonous Basque population.

Population data studies for six short-tandem repeat loci (HUMCSF1P0, HUMTPOX, HUMTH01, HUMHPRTB, HUMFES/FPS, and HUMvWF) were carried out on a sample of 326 autochthonous Basques. Comparing with other European samples, we found the highest frequencies known so far for allele 11 of the HUMCSF1P0 locus (0.380), allele 10 of the HUMFES/FPS locus (0.384), and allele 17 of the HUMvWF locus (0.329). On the other hand, we found the lowest frequencies recorded in Europe for allele 12 of the HUMCSF1P0 locus (0.291), allele 7 of the HUMTH01 locus (0.128), and allele 11 of the HUMFES/FPS system (0.317). These results support the hypothesis that the Basque population is a remnant of early European settlers.

Ethnicity↗