Search PubMed⌕ Search

Biomedical subjects

J Llopis

Publications and source records attributed to J Llopis.

At least 19 recordsLinked to original sources
PubMed2001

High-grade prostate intraepithelial neoplasia shares cytogenetic alterations with invasive prostate cancer.

BACKGROUND: High-grade prostate intraepithelial neoplasia (PIN) is the most likely precursor of prostate adenocarcinoma. However, the relationship between this lesion and prostate cancer has not yet been established. The detection of cytogenetic changes in the lesions prior to prostate adenocarcinoma would be useful in demonstrating such a pathogenic relationship. METHODS: Twenty eight high-grade PIN cases were found among 57 specimens of radical prostatectomy performed for clinically localized prostate cancer. Fluorescence in situ hybridization (FISH) analysis using centromeric probes to enumerate chromosomes 7, 8, 10, and 12 was performed to study the numerical chromosome alterations. FISH analysis was carried out over isolated nuclei obtained from high-grade PIN areas and prostate cancer foci in the same prostatectomy specimen. RESULTS: Of the 28 suitable cases it was possible to complete the study in 26 tumor and 20 PIN areas. The remaining cases were excluded because of insufficient tissue or poor preservation. Cytogenetic alterations (aneuploidy) were found in 16 of the 26 (62%) tumors studied. The most frequent chromosome alteration was trisomy 7, detected in 12 (75%) aneuploid tumors, followed by monosomy 8 present in 5 (31%) aneuploid tumors. Trisomy 7 was also the most frequent isolated chromosome alteration since it was detected in 7 (44%) tumors. Thirteen of 20 (65%) PIN cases were aneuploid when studied by FISH. Trisomy 7, trisomy 8, and monosomy 8 were the most common cytogenetic alterations in the 20 PIN areas studied, being observed in nine (45%), six (30%), and four (20%) cases, respectively. FISH analysis showed a high correlation (75% cases) in ploidy and pattern of cytogenetic alterations between high-grade PIN areas and the paired prostate cancer focus in the same specimen. CONCLUSIONS: The above results show a cytogenetic link between high-grade PIN and prostate cancer, suggesting that the former could be an early form of prostate cancer.

Adenocarcinoma↗
PubMed2001

Vitamins in Spanish food patterns: the eVe Study.

OBJECTIVE: To describe vitamin intakes in Spanish food patterns, identify groups at risk for inadequacy and determine conditioning factors that may influence this situation. DESIGN: Pooled-analysis of eight cross-sectional regional nutrition surveys. SUBJECTS: Ten thousand two hundred and eight free-living subjects (4728 men, 5480 women) aged 25-60 years. Respondents of population nutritional surveys carried out in eight Spanish regions (Alicante, Andalucia, Balearic Islands, Canary Islands, Catalunya, Galicia, Madrid and Basque Country) from 1990 to 1998. The samples were pooled together and weighted to build a national random sample. METHODS: Dietary assessment by means of repeated 24-hour recall using photograph models to estimate portion size. Adjusted data for intra-individual variation were used to estimate the prevalence of inadequate intake. A Diet Quality Score (DQS) was computed considering the risk for inadequate intake for folate, vitamin C, vitamin A and vitamin E. DQS scores vary between 0 (good) and 4 (very poor). Influence of lifestyle (smoking, alcohol consumption and physical activity) was considered as well. RESULTS: Inadequate intakes (<2/3 Recommended Dietary Intake) were estimated in more than 10% of the sample for riboflavin (in men), folate (in women), vitamin C, vitamin A, vitamin D and vitamin E. More than 35% of the sample had diets classified as poor quality or very poor quality. Factors identified to have an influence on a poor-quality diet were old age, low education level and low socio-economical level. A sedentary lifestyle, smoking, usual consumption of alcohol and being overweight were conditioning factors for a poor-quality diet as well. CONCLUSION: Results from The eVe Study suggest that a high proportion of the Spanish population has inadequate intakes for at least one nutrient and nearly 50% should adjust their usual food pattern towards a more nutrient-dense, healthier diet.

Adult↗
PubMed2001

Alcohol consumption and academic performance in a population of Spanish high school students.

OBJECTIVE: The present study was designed to identify patterns of alcohol consumption among Spanish high school students and describe the relationship between alcohol intake and school performance. METHOD: The sample population consisted of students, aged 14 to 19 years, who were attending high school during the academic year 1994-95 in the city of Granada in southern Spain. We studied 1,602 (861 female) students (alpha error - 0.05, sampling error = 5%), using a self-administered questionnaire that contained items about individual and family demographics, quantity and frequency of alcohol consumption, and school performance. Total alcohol consumption was recorded as grams (g) of alcohol per week and per day for three categories of alcoholic drinks: wine, beer and distilled spirits. RESULTS: The percentage of nondrinkers was 21.05% for male adolescents and 28.56% for female adolescents. The mean amount of alcohol consumed per week was larger in male than in female students (F= 18.36, l/l,594 df, p < .001) and distilled spirits accounted for the largest proportion of alcohol consumed. No significant differences in drinking patterns were found between students at public and private schools. The risk of academic failure increased considerably when more than 150 g of alcohol were consumed per week (OR: 2.91; 95% CI: 1.94-4.43). CONCLUSIONS: Although we cannot draw any conclusions about the causes of the association between academic failure and teenage drinking, our results do show that the risk of failing increases together with alcohol intake. However, it should be noted that academic achievement is also influenced by many factors other than alcohol consumption.

Achievement↗
PubMed2000

Cellular regulation of cytosolic group IV phospholipase A2 by phosphatidylinositol bisphosphate levels.

Cytosolic group IV phospholipase A2 (cPLA2) is a ubiquitously expressed enzyme with key roles in intracellular signaling. The current paradigm for activation of cPLA2 by stimuli proposes that both an increase in intracellular calcium and mitogen-activated protein kinase-mediated phosphorylation occur together to fully activate the enzyme. Calcium is currently thought to be needed for translocation of the cPLA2 to the membrane via a C2 domain, whereas the role of cPLA2 phosphorylation is less clearly defined. Herein, we report that brief exposure of P388D1 macrophages to UV radiation results in a rapid, cPLA2-mediated arachidonic acid mobilization, without increases in intracellular calcium. Thus, increased Ca2+ availability is a dispensable signal for cPLA2 activation, which suggests the existence of alternative mechanisms for the enzyme to efficiently interact with membranes. Our previous in vitro data suggested the importance of phosphatidylinositol 4,5-bisphosphate (PtdInsP2) in the association of cPLA2 to model membranes and hence in the regulation of cPLA2 activity. Experiments described herein show that PtdInsP2 also serves a similar role in vivo. Moreover, inhibition of PtdInsP2 formation during activation conditions leads to inhibition of the cPLA2-mediated arachidonic acid mobilization. These results suggest that cellular PtdInsP2 levels are involved in the regulation of group IV cPLA2 activation.

Animals↗
PubMed2000

Ligand-dependent interactions of coactivators steroid receptor coactivator-1 and peroxisome proliferator-activated receptor binding protein with nuclear hormone receptors can be imaged in live cells and are required for transcription.

Members of the nuclear receptor superfamily are thought to activate transcription by recruitment of one or more recently identified coactivator complexes. Here we demonstrate that both peroxisome proliferator-activated receptor binding protein (PBP) and steroid receptor coactivator-1 (SRC-1) are required for ligand-dependent transcription of transiently transfected and chromosomally integrated reporter genes by the estrogen receptor (ER) and retinoic acid receptor (RAR). To examine ligand-dependent interactions between nuclear receptors and specific coactivators in living cells, these proteins were tagged with cyan (CFP) and yellow (YFP) mutants of the green fluorescent protein. Fluorescence resonance energy transfer (FRET) from the CFP to the YFP indicated interaction between the receptor and coactivator. CFP fusions to RAR or its ligand-binding domain exhibited rapid ligand-dependent FRET to YFP-tagged nuclear receptor interaction domains of the coactivators SRC-1 and PBP. The ER-ligand-binding domain, unlike RAR, also exhibited some basal interaction with coactivators in unstimulated cells that was abolished by the receptor antagonists tamoxifen or ICI182,780. Inhibition of FRET by tamoxifen but not ICI182,780 could be reversed by estradiol, whereas estradiol-enhanced FRET could not be inhibited by either antagonist, indicating that ligand effects can show varying degrees of hysteresis. These findings suggest that ligand-dependent transcriptional activities of the RAR and ER require concurrent or sequential recruitment of SRC-1 and PBP-containing coactivator complexes.

Carrier Proteins↗
PubMed2000

Effect of magnesium deficiency on enterocyte Ca, Fe, Cu, Zn, Mn and Se content.

In previous studies based on indirect procedures, we reported that Mg deficit increased the bioavailability of a number of elements such as calcium, zinc, iron, copper, manganese and decreased selenium absorption. The present study was designed to verify these findings by direct methods. We investigated the effect of dietary magnesium deficiency on enterocyte Ca, Fe, Zn, Cu, Mn and Se concentrations. Male Wistar rats were fed a Mg-deficient diet (129 mg Mg/kg food) for 70 days. Whole enterocytes from the upper jejunum were isolated and Ca, Fe, Zn, Cu, Mn and Se were determined. The results were compared with findings in a control group that was pair-fed with an identical diet except that it covered this species's nutritional requirements for Mg (480 mg Mg/kg food). The Mg-deficient diet significantly increased enterocyte content of Ca, Fe, Zn, Cu and Mn; however, we found no significant changes in the Se content of these cells. These data support the results obtained by indirect methods.

Animals↗
PubMed2000

Influence of magnesium deficiency on the bioavailability and tissue distribution of iron in the rat.

We investigated the effect of dietary magnesium (Mg) deficiency on the nutritive utilization and tissue distribution of iron (Fe). Wistar rats were fed an Mg-deficient diet (56 mg/kg) for 70 days. Absorbed Fe, Fe balance, number of the erythrocytes [red blood cells (RBC)] and leukocytes white blood cells (WBC)], hemoglobin (Hb), and Fe content were determined in samples of plasma, whole blood, skeletal muscle, heart, kidney, liver, spleen, femoral bone, and sternum obtained on experimental days 21, 35, and 70. The Mg-deficient diet significantly increased Fe absorption and Fe balance from week 5 until the end of the experimental period. This effect was accompanied by a significant decrease in the concentration of RBC and Hb from day 35, which caused the decrease in whole blood Fe seen on day 70. However, WBC were significantly increased from day 21 until the end of the experimental period. Mg deficiency significantly increased plasma and liver Fe at all three time points investigated. Spleen, heart, and kidney Fe were significantly increased only at the end of the study. However, on day 70, Fe concentration in the sternum had decreased significantly. No changes were found in skeletal muscle or femur Fe content. Mg deficiency led to increased intestinal absorption of Fe and decreased RBC counts, possibly as a result of increased fragility of the erythrocytes. Intestinal interactions between Fe and Mg, together with activation of erythropoiesis as a result of hemolysis, favored intestinal absorption of Fe. This situation gave rise to an increase in plasma Fe levels, which in turn favored Fe uptake and storage by different organs, especially the liver and spleen. However, despite the increased Fe content seen in the tissues of rats fed the Mg-deficient diet, these animals were unable to compensate for the hemolysis caused by this nutritional deficiency.

Journal Article↗
PubMed2000

Organelle pH studies using targeted avidin and fluorescein-biotin.

BACKGROUND: Mammalian organelles of the secretory pathway are of differing pH. The pH values form a decreasing gradient: the endoplasmic reticulum (ER) is nearly neutral, the Golgi is mildly acidic and the secretory granules are more acidic still ( approximately pH 5). The mechanisms that regulate pH in these organelles are still unknown. RESULTS: Using a novel method, we tested whether differences in H(+) 'leak' and/or counterion conductances contributed to the pH difference between two secretory pathway organelles. A pH-sensitive, membrane-permeable fluorescein-biotin was targeted to endoplasmic-reticulum- and Golgi-localized avidin-chimera proteins in HeLa cells. In live, intact cells, ER pH (pH(ER)) was 7.2 +/- 0.2 and Golgi pH (pH(G)) was 6.4 +/- 0.3 and was dissipated by bafilomycin. Buffer capacities of the cytosol, ER and Golgi were all similar (6-10 mM/pH). ER membranes had an apparent H(+) permeability three times greater than that of Golgi membranes. Removal of either K(+) or Cl(-) did not affect ER and Golgi H(+) leak rates, or steady-state pH(G) and pH(ER). CONCLUSIONS: The Golgi is more acidic than the ER because it has an active H(+) pump and fewer or smaller H(+) leaks. Neither buffer capacity nor counterion permeabilities were key determinants of pH(G), pH(ER) or ER/Golgi H(+) leak rates.

Avidin↗
PubMed2000

Changes in intramitochondrial and cytosolic pH: early events that modulate caspase activation during apoptosis.

Mitochondria trigger apoptosis by releasing caspase activators, including cytochrome c (cytC). Here we show, using a pH-sensitive green fluorescent protein (GFP), that mitochondria-dependent apoptotic stimuli (such as Bax, staurosporine and ultraviolet irradiation) induce rapid, Bcl-2-inhibitable mitochondrial alkalinization and cytosol acidification, followed by cytC release, caspase activation and mitochondrial swelling and depolarization. These events are not induced by mitochondria-independent apoptotic stimuli, such as Fas. Activation of cytosolic caspases by cytC in vitro is minimal at neutral pH, but maximal at acidic pH, indicating that mitochondria-induced acidification of the cytosol may be important for caspase activation; this finding is supported by results obtained from cells using protonophores. Cytosol acidification and cytC release are suppressed by oligomycin, a FoF1-ATPase/H +-pump inhibitor, but not by caspase inhibitors. Ectopic expression of Bax in wild-type, but not FoF1/H+-pump-deficient, yeast cells similarly results in mitochondrial matrix alkalinization, cytosol acidification and cell death. These findings indicate that mitochondria-mediated alteration of intracellular pH may be an early event that regulates caspase activation in the mitochondrial pathway for apoptosis.

Animals↗
PubMed2000

Response

Explore the source record for details and available documents.

Journal Article↗
PubMed2000

p53 expression predicts progression and poor survival in T1 bladder tumours.

OBJECTIVES: Histological grade (G) is the only parameter proved to have prognostic value for progression in T1 transitional cell carcinoma (TCC) of the bladder, although it is considered inaccurate to make clinical decisions on individuals. The aim of the present study was to evaluate the prognostic relevance of p53 expression in T1 TCC of the bladder. METHODS: Clinical records of 207 patients with T1 TCC of the bladder were reviewed for clinical parameters reported to influence the evolution of superficial bladder cancer. Among these 207 patients, 40 developed muscle-invasive disease (20 G2 and 20 G3). A retrospective case-control study was then carried out comparing the latter 40 tumours with 40 control tumours matched by grade, sex, age, number and size of the tumours, chemical exposure and presence of carcinoma in situ. p53 immunostaining with monoclonal antibody was performed in these two groups. RESULTS: Histological grade was the only clinical parameter that influenced evolution. p53 expression correlated with tumour progression, since it was observed in 21 out of 24 p53-positive tumours and in only 20 of 56 p53-negative tumours (p<0.0001), showing a specificity of 93. 5% and a sensitivity of 53%. p53 expression correlated as well with patient survival, being 39% in patients with p53-positive tumours and 80% in patients with p53-negative tumours at 60 months (p<0. 0001). CONCLUSIONS: p53 protein expression has prognostic value for survival and progression in T1 bladder tumours and can be used for early detection of poor-prognosis T1 bladder tumours.

Adult↗
PubMed1999

Ability of a cocoa product to correct chronic Mg deficiency in rats.

Epidemiological studies have reported that Western diets are often deficient in Mg. We investigated the ability of a cocoa-derived product, used in some European countries as a dietary complement added to milk, to aid recovery from chronic Mg deficiency in rats. The animals were divided into three groups, each of which received a different amount of dietary Mg. Rats in the Mg-deficient (D) group received an Mg-deficient diet (0.225 g Mg/kg food) during 8 weeks. In the cocoa-supplement group (D + CC), the rats consumed the Mg-deficient diet for 5 weeks, and were then switched for 3 further weeks to the same diet supplemented with 3% (wt/wt) cocoa product, so that the Mg content of the diet was 0.27 g/kg food. Rats in the control group (C) were given the same diet as in group D, except that the amount of Mg was 0.56 g Mg/kg food. We measured the concentration of Mg, Ca and P from ten rats in plasma, whole blood, skeletal muscle, heart, kidney and femur in rats that were fed the diets for 35, 42, 49 or 56 days. In animal fed the cocoa-supplemented diet (D + CC) significant improvements were found between days 35 and 56 in the alterations in Mg, Ca and P caused by Mg deficiency in all tissues studied. On day 56, kidney and bone concentrations of Mg and Ca had returned to normal. Our findings show that the habitual use of the cocoa product as a dietary supplement favors correction of the negative effects of long-term feeding with a diet moderately deficient in Mg.

Animals↗
PubMed1999

Cameleon calcium indicator reports cytoplasmic calcium dynamics in Arabidopsis guard cells.

Cytoplasmic free calcium ([Ca2+]cyt) acts as a stimulus-induced second messenger in plant cells and multiple signal transduction pathways regulate [Ca2+]cyt in stomatal guard cells. Measuring [Ca2+]cyt in guard cells has previously required loading of calcium-sensitive dyes using invasive and technically difficult micro-injection techniques. To circumvent these problems, we have constitutively expressed the pH-independent, green fluorescent protein-based calcium indicator yellow cameleon 2.1 in Arabidopsis thaliana (Miyawaki et al. 1999; Proc. Natl. Acad. Sci. USA 96, 2135-2140). This yellow cameleon calcium indicator was expressed in guard cells and accumulated predominantly in the cytoplasm. Fluorescence ratio imaging of yellow cameleon 2.1 allowed time-dependent measurements of [Ca2+]cyt in Arabidopsis guard cells. Application of extracellular calcium or the hormone abscisic acid (ABA) induced repetitive [Ca2+]cyt transients in guard cells. [Ca2+]cyt changes could be semi-quantitatively determined following correction of the calibration procedure for chloroplast autofluorescence. Extracellular calcium induced repetitive [Ca2+]cyt transients with peak values of up to approximately 1.5 microM, whereas ABA-induced [Ca2+]cyt transients had peak values up to approximately 0.6 microM. These values are similar to stimulus-induced [Ca2+]cyt changes previously reported in plant cells using ratiometric dyes or aequorin. In some guard cells perfused with low extracellular KCl concentrations, spontaneous calcium transients were observed. As yellow cameleon 2.1 was expressed in all guard cells, [Ca2+]cyt was measured independently in the two guard cells of single stomates for the first time. ABA-induced, calcium-induced or spontaneous [Ca2+]cyt increases were not necessarily synchronized in the two guard cells. Overall, these data demonstrate that that GFP-based cameleon calcium indicators are suitable to measure [Ca2+]cyt changes in guard cells and enable the pattern of [Ca2+]cyt dynamics to be measured with a high level of reproducibility in Arabidopsis cells. This technical advance in combination with cell biological and molecular genetic approaches will become an invaluable tool in the dissection of plant cell signal transduction pathways.

Amino Acid Sequence↗
PubMed1999

Magnesium-manganese interactions caused by magnesium deficiency in rats.

OBJECTIVE: We investigated the effect of dietary magnesium (Mg) deficiency on the nutritive utilization and tissue distribution of manganese (Mn). METHODS: Wistar rats were fed a Mg-deficient diet (56 mg/kg) for 70 day. Absorbed Mn, Mn balance and Mn content in plasma, whole blood, skeletal muscle, heart, kidney, liver, femoral bone and sternum were determined after 21, 35 and 70 days. RESULTS: The Mg-deficient diet significantly increased Mn apparent absorption and Mn balance from week five until the end of the experimental period. This effect was accompanied by a significant increase in the concentration of Mn in heart at all three time points. Whole blood, skeletal muscle and kidney Mn were significantly increased from day 35, and femur Mn content was increased only at the end of the study (day 70). However, Mn concentration in the sternum decreased significantly from day 35. No changes were found in liver Mn content. CONCLUSION: Mg deficiency increased Mn absorbed, and this favored the deposition of Mn in all tissues studied except the liver and trabecular bone. The lack of response by the liver to increased Mn absorption may have led to the redistribution of this ion to other tissues.

Absorption↗