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Biomedical subjects

A Lázaro

Publications and source records attributed to A Lázaro.

At least 19 recordsLinked to original sources
PubMed2004

Ouabain binding to Na+,K+-ATPase relaxes cell attachment and sends a specific signal (NACos) to the nucleus.

Abstract. In previous work we described a "P-->A mechanism" that transduces occupancy of the pump ( P) by ouabain into changes in phosphorylation, stimulation of mitogen-activated protein kinase (MAPK), and endocytosis of cell-cell- and cell-substrate-attaching molecules ( A), thereby causing a release of the cell from the monolayer. In the present work we try to understand the mechanism of this effect; whether, in order to trigger the P-->A mechanism, ouabain should block the pumping activity of Na(+),K(+)-ATPase as pump, or whether it would suffice that the drug occupies this enzyme as a receptor. We assay a series of drugs known to act on the pump, such as ouabain, digoxin, digitoxin, palytoxin, oligomycin, strophanthidin, neothyoside-A, proscillaridin-A, etc. We gauge their ability to block the pump by measuring the K(+) content in the cells, and their ability to detach the cells from the monolayer by determining the amount of protein remaining in the culturing well. None of the drugs tested was able to cause detachment without stopping the pump. Ouabain also enhances phosphorylation, yet pump inhibition and signal transduction do not seem to be intimately associated in a causal chain, but to occur simultaneously. To investigate the response of the site of cell attachment, we analyze the position of beta-catenin by fluorescence confocal microscopy, and find that this adherent junction-associated molecule is sent to the nucleus, where it is known to act as a transcriptional cofactor.

Animals↗
PubMed2000

Dietary fat intake and body mass index in Spanish children.

Our objectives were to describe the pattern of dietary fat intake and to present data on trends of growth in Spanish children in past decades. In 1984 a nationwide nutritional survey was conducted in Spain. The average nationwide fat intake was 42% of energy. Across different regions, saturated fat intakes ranged from 13% to 15% of energy and monounsaturated fat intakes ranged from 18% to 19% of energy. More recently, some surveys were conducted at a regional or local level. In children aged 6-10 y, total fat intake ranged from 38% to 48% of energy, of which saturated fat intake ranged from 16% to 18% and monounsaturated fat ranged from 19% to 20%. In children aged 11-14 y, total fat intake ranged from 41% to 51% of energy, of which saturated fat intake ranged from 12% to 18% and monounsaturated fat intake accounted for 20%. In our region of Aragón, we observed a significant trend in children's growth, especially when we accounted for body mass index. The results reflect an increasing total fat consumption in Spain, especially of saturated and monounsaturated fat. The following question remains unanswered: what percentage of fat intake should be recommended when monounsaturated fat is the principal source of fat? Trends on body mass index values in children of our region during the past decades could be related to the amount of fat intake in our population. To confirm these findings we must measure dietary fat intake and nutritional status in the same population of children and adolescents.

Adolescent↗
PubMed1999

Relationship between Na(+),K(+)-ATPase and cell attachment.

A prolonged ouabain blockade of the Na(+),K(+)-ATPase detaches cells from each other and from the substrate. This suggests the existence of a link between pump (P) and attachment (A). In the present work, we report that MDCK-W cells treated with ouabain increase tyrosine phosphorylation and content of active MAP kinase, redistribute molecules involved in cell attachment (occludin, ZO-1, desmoplakin, cytokeratin, alpha-actinin, vinculin and actin), and detach. Genistein and UO126, inhibitors of protein tyrosine kinase and of MAP kinase kinase, respectively, block this detachment. The content of P190(Rho-GAP), a GTPase activating protein of the Rho small G-protein subfamily, is increased by ouabain, suggesting that both the Rho/Rac and MAPK pathways are involved. Another clone of MDCK cells whose Na(+),K(+)-ATPase has a negligible affinity for the drug, show none of the effects described for MDCK-W and remain attached. Ma104 cells, a line that has a high affinity for ouabain and stops pumping, fail to modify phosphorylation, as well as the pattern of distribution of attaching molecules, and remain in the monolayer. Taken together, these results suggest that there is a mechanism (P-->A) that transduces a blockade of the pump in a detachment of the cell from neighbors and substrate, in which Ma104 cells are faulty.

Actinin↗
PubMed1999

[Multicenter study of the variability and adequacy of antimicrobial therapy for community-acquired pneumonia in adults].

We performed a study to evaluate the variability and adequacy of prescribing antibiotics in community-acquired pneumonia (CAP) in 10 Spanish hospitals. We studied 452 patients with CAP. Initial empirical administration of antibiotics was prescribed in 90.7% of the cases, 82.5% as monotherapy. Macrolides and third and second generation cephalosporins were the most widely used groups of antibiotics. Penicillin and amoxicillin were only prescribed in 1. 7% of the patients. A significant variability between hospitals was observed. Reference patterns for the use of antibiotics in CAP were devised by a panel of experts. According to the recommendations of this panel, 29% of the total prescriptions were not adequate, with this percentage reaching 65% in outpatients older than 65 years or with comorbidity. This was mainly due to the fact that monotherapy with erythromycin, which was considered inadequate, was the most widely prescribed treatment.

Adult↗
PubMed1999

[Multicenter study of the variability and adequacy of antimicrobial therapy for community-acquired pneumonia in adults]

We performed a study to evaluate the variability and adequacy of prescribing antibiotics in community-acquired pneumonia (CAP) in 10 Spanish hospitals. We studied 452 patients with CAP. Initial empirical administration of antibiotics was prescribed in 90.7% of the cases, 82.5% as monotherapy. Macrolides and third and second generation cephalosporins were the most widely used groups of antibiotics. Penicillin and amoxicillin were only prescribed in 1.7% of the patients. A significant variability between hospitals was observed. Reference patterns for the use of antibiotics in CAP were devised by a panel of experts. According to the recommendations of this panel, 29% of the total prescriptions were not adequate, with this percentage reaching 65% in outpatients older than 65 years or with comorbidity. This was mainly due to the fact that monotherapy with erythromycin, which was considered inadequate, was the most widely prescribed treatment.

Journal Article↗
PubMed1998

Tight junctions and the experimental modifications of lipid content.

Tight junctions (TJs) are cell-to-cell contacts made of strands, which appear as ridges on P faces and complementary furrows on E faces on freeze fracture replicas. Evidences and opinions on whether these strands are composed of either membrane-bound proteins or lipid micelles are somewhat varied. In the present work we alter the lipid composition of Madin-Darby canine kidney monolayers using a novel approach, while studying (i) their transepithelial electrical resistance, a parameter that depends on the degree of sealing of the TJs; (ii) the apical-to-basolateral flux of 4 kD fluorescent dextran (JDEX), that reflects the permeability of the intercellular spaces; (iii) the ability of TJs to restrict apical-to-basolateral diffusion of membrane lipids; and (iv) the pattern of distribution of endogenous and transfected occludin, the sole membrane protein presently known to form part of the TJs. We show that changing the total composition of phospholipids, sphingolipids, cholesterol and the content of fatty acids, does not alter TER nor the structure of the strands. Interestingly, enrichment with linoleic acid increases the JDEX by 631%. The fact that this increase is not reflected in a decrease of TER, suggests that junctional strands do not act as simple resistive elements but may contain mobile translocating mechanisms.

Animals↗
PubMed1998

Lymphocyte T subset counts in children with hypercholesterolemia receiving dietary therapy.

BACKGROUND: In children with hypercholesterolemia, dietary therapy is indicated; however, we do not know if a low-fat diet can modify some organic functions, i.e. immune function. METHODS: 42 children with hypercholesterolemia received a low-fat, low-cholesterol diet during 6 months. At baseline and after the treatment period, we determined a lipoprotein profile and some immune characteristics: immunoglobulins G, A and M; complement components (C3, C4 and factor B), and blood lymphocyte subsets (CD3, CD4 and CD8). RESULTS: Total cholesterol serum concentrations showed a significant reduction after 6 months of dietary therapy (p = 0.008). After 6 months on a low-fat diet, lymphocyte T subset counts (CD3, CD4 and CD8) showed significant decreases (p < 0.01 to p < 0.003), but lymphocyte counts were always within normal ranges. There was also a significant correlation between changes in some lymphocyte T subset counts (CD3 and CD8) and changes in triglyceride serum concentrations (p < 0.05). CONCLUSIONS: A low-fat, low-cholesterol diet diminished CD3, CD4 and CD8 lymphocyte subset counts that are elevated in children with hypercholesterolemia. Dietary therapy, with emphasis on the intake of n-3 fatty acids, could be useful in the modulation of the immune response at the atheromatous plaque level.

Adolescent↗
PubMed1998

[Effectiveness of topical anesthesia enhanced by sedation and analgesia for cataract surgery].

OBJECTIVES: To compare the efficacy of topical anesthesia and retrobulbar anesthesia for cataract surgery by lens emulsification. PATIENTS AND METHODS: Two hundred sixty patients were randomized to two groups in this open clinical trial. Patients with cataracts that could not be treated by lens emulsification were excluded. Group I patients (n = 129) received 0.5% tetracaine drops and intravenous fentanyl and propofol, along with continuous sedation. Group II patients (n = 131) received 2% lidocaine in the retrobulbar space and hypnotic doses of intravenous propofol before retrobulbar injection. The anesthesiologist evaluated anesthesia negatively if SpO2 was 90% and either heart rate or blood pressure varied more than 20%. The ophthalmologist evaluated anesthesia negatively if the eye did not remain fixed in the center, if blepharospasm appeared or if the anterior chamber of the eye collapsed. The patient reported the intensity of any discomfort experienced on a six-point scale. Anesthesia was determined to be effective when favorable evaluations were given by both the anesthesiologist and the ophthalmologist and when no significant discomfort (first three points on the scale) was reported by the patient. The two treatment groups were compared using a single and multiple factor analysis. RESULTS: Group II experienced significantly fewer instances of ineffective anesthesia than did group I (8 versus 22) and fewer negative evaluations by the ophthalmologists (7 versus 18). More patients in group I reported discomfort than in group II (46 versus 9), although most complaints were of slight discomfort. Multiple factor analysis showed that a patient in group I had 4.64 more chances of experiencing ineffective anesthesia. CONCLUSIONS: Topical anesthesia is less effective than retrobulbar anesthesia for cataract surgery by lens emulsification.

Aged↗
PubMed1996

Relationship between immunoinflammatory proteins containing sialic acid and low-density lipoprotein serum concentrations.

The aim of this study was to investigate the relationship between sialoglycoproteins and the lipoprotein profile in a group of children with different levels of low-density lipoprotein cholesterol. We have studied 177 children of 132 families who were sent to our Pediatric Lipid Research Clinic because of serum cholesterol concentrations higher than 5.17 mmol/l. At the time of diagnosis, we analyzed the serum lipoprotein profile and the sialoglycoproteins: alpha 1-antitrypsin, acid alpha 1-glycoprotein, haptoglobin, alpha 2-macroglobulin, transferrin, IgA, IgG, IgM, complement C3 component and ceruloplasmin. At 7.0 to 10.9 years, alpha 1-glycoprotein serum concentrations were higher in the high risk group than in the moderate risk group (P < 0.05). At 2.0 to 6.9 years, IgA and IgM serum concentrations were higher in the moderate risk group than in the low risk group (P < 0.05 and P < 0.01, respectively), and IgG and IgM serum concentrations were also higher in the high risk group than in the low risk group (P < 0.05). Our results seems to reflect a general reaction to injury or inflammation which could be associated with the atherosclerotic process.

Adolescent↗
PubMed1995

Ouabain resistance of the epithelial cell line (Ma104) is not due to lack of affinity of its pumps for the drug.

Na+, K(+)-pumps of most eukaryotic animal cells bind ouabain with high affinity, stop pumping, and consequently loose K+, detach from each other and from the substrate, and die. Lack of affinity for the drug results in ouabain resistance. In this work, we report that Ma104 cells (epithelial from Rhesus monkey kidney) have a novel form of ouabain-resistance: they bind the drug with high affinity (Km about 4 x 10(-8) M), they loose their K+ and stop proliferating but, in spite of these, up to 100% of the cells remain attached in 1.0 microM ouabain, and 53% in 1.0 mM. When 4 days later ouabain is removed from the culture medium, cells regain K+ and resume proliferation. Strophanthidin, a drug that attaches less firmly than ouabain, produces a similar phenomenon, but allows a considerably faster recovery. This reversal may be associated to the fact that, while in ouabain-sensitive MDCK cells Na+, K(+)-ATPases blocked by the drug are retrieved from the plasma membrane, those in Ma104 cells remain at the cell-cell border, as if they were cell-cell attaching molecules. Cycloheximide (10 micrograms/ml) and chloroquine (10 microM) impair this recovery, suggesting that it also depends on the synthesis and insertion of a crucial protein component, that may be different from the pump itself. Therefore ouabain resistance of Ma104 cells is not due to a lack of affinity for the drug, but to a failure of its Na+, K(+)-ATPases to detach from the plasma membrane in spite of being blocked by ouabain.

Animals↗
PubMed1995

A novel type of cell-cell cooperation between epithelial cells.

Ma104 cells (renal, epithelial) have a peculiar way of resisting ouabain: their Na+,K(+)-pumps bind the drug with high affinity, cellular K+ is lost and cell division arrested, but cells do not detach as most cell types do. Then, if up to 4 days later the drug is removed, Ma104 cells recover K+ and resume proliferation (Contreras et al., 1994). In the present work, we investigate whether Ma104 cells are able to protect ouabain-sensitive MDCK cells in co-culture. The main finding is that they do, but in this case protection is not elicited by the usual mechanism of maintaining the K+ content of neighboring cells through cell-cell communications. Ma104 cells treated with ouabain simply remain attached to the substrate and to their MDCK neighbors, and both cells lose K+. This attachment includes tight junctions, because the transepithelial electrical resistance of the monolayers is not abolished by ouabain. Although the beta-subunit of the Na+,K(+)-ATPase is known to possess molecular characteristics of cell-cell attachment molecules, attachment between Ma104-MDCK cells does not seem to be mediated by this enzyme, as immunofluorescence analysis reveals that Na+,K(+)-ATPase is only inserted in the plasma membrane facing a neighboring cell of the same type.

Animals↗
PubMed1995

Lymphocyte T subset counts in children with elevated low-density lipoprotein cholesterol levels.

The aim of this study was to determine blood lymphocyte T subset counts in children with elevated levels of low-density lipoprotein cholesterol. We studied 107 children, ages 2.0 to 15.9 years, from 79 families who were referred to our Lipid Research Clinic because total cholesterol serum levels higher than 200 mg/dl had been detected in at least one child. At the time of diagnosis we analyzed serum lipoprotein profile and blood lymphocyte T subsets (CD3, CD4 and CD8). Children were classified according to LDL-C levels into three groups: (1) normal, if levels were between the 5th and 75th percentiles (50 and 125 mg/dl, respectively); (2) at moderate risk, if levels were between the 75th and 95th percentiles (125 and 150 mg/dl, respectively); and (3) at high risk, if levels were above the 95th percentile (150 mg/dl). In children aged 2.0 to 6.9 years, all lymphocyte T subset counts were higher in the high risk group than in the normal group (P < 0.05 and P < 0.01). In children aged 11.0 to 15.9 years, the CD4 subset count was also significantly higher in the high risk group in the other two groups (P < 0.05 and P < 0.01). These results are in agreement with pathologic findings in the atheromatous plaque.

Adolescent↗
PubMed1992

Usefulness of serum apolipoprotein B levels for screening children with primary dyslipoproteinemias.

OBJECTIVE: To assess the use of serum apolipoprotein B levels for screening children with primary dyslipoproteinemia (those with elevated levels of low-density lipoprotein cholesterol [LDL-C]) and to know the types of dyslipoproteinemias we can identify. DESIGN: Criterion standard. SETTING: Referral center. PARTICIPANTS: We have studied 267 children. Of these, 31 had parents with dyslipoproteinemia, 38 had parents with ischemic heart disease, and 43 had hypercholesterolemia detected by routine analyses. One hundred fifty-five were considered healthy children and comprised the control group. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Sensitivity was 87% for total serum cholesterol levels and 73% for serum apolipoprotein B levels. Of the children studied, 31 had elevated levels of serum LDL-C. The types of dyslipoproteinemia in children with both elevated levels of serum LDL-C and apolipoprotein B consisted of heterozygous familial hypercholesterolemia, found in 12 (50%) of 24 patients; familial combined hyperlipidemia, found in 11 (46%) of 24 patients; and polygenic hypercholesterolemia, found in one (4%) of 24 patients. CONCLUSIONS: Serum apolipoprotein B level appears to be a good tool for screening children with elevated levels of LDL-C and is equivalent to using total serum cholesterol levels. In children with elevated serum LDL-C and apolipoprotein B levels, we can identify not only patients with heterozygous familial hypercholesterolemia but also those with familial combined hyperlipidemia or polygenic hypercholesterolemia.

Adolescent↗
PubMed1992

Effect of low doses of deflazacort vs prednisone on bone mineral content in premenopausal rheumatoid arthritis.

Longterm administration of steroid drugs, particularly prednisone, is known to induce osteoporosis, as well as bone growth inhibition and delayed fracture union. Recently deflazacort, an oxazoline prednisone derivative, has been developed to reduce such deleterious effects. We carried out a comparative study in premenopausal patients with rheumatoid arthritis (RA). Sixteen cases whose mean age was 36.5 years and mean disease duration 29 months, all fulfilling ARA criteria, were evaluated in a randomized, double blind trial. Visually identical deflazacort or prednisone capsules were given and patients were instructed to maintain an adequate calcium intake. Laboratory tests focussed on bone mineral density in lumbar spine, femoral neck and Ward's triangle and whole body mineral content. Differences between baseline and 12-month values were processed statistically. Persistent synovitis control proved similar for both drugs and features suggestive of Cushing's syndrome were only found in the prednisone group. The difference in whole body bone mineral content between the deflazacort and prednisone groups just failed to reach statistical significance. In the deflazacort group, the difference between the nonsignificant bone mineral density increase at the femoral neck and the significant decrease in the prednisone group proved statistically significant. Ward's triangle was the most sensitive area to bone mineral density changes in patients receiving prednisone, with a highly significant intergroup difference (p < 0.01). We believe this is the first study on corticosteroid induced osteoporosis, as evaluated by whole body mineral content measurements in premenopausal patients with short term RA, showing that deflazacort is a promising alternative in cases severe enough to require steroid therapy.

Adult↗
PubMed1991

Osmolarity-sensitive release of free amino acids from cultured kidney cells (MDCK).

The amino acid pool of MDCK cells was essentially constituted by alanine, glycine, glutamic acid, serine, taurine, lysine, beta-alanine and glutamine. Upon reductions in osmolarity, free amino acids were rapidly mobilized. In 50% hyposmotic solutions, the intracellular content of free amino acids decreased from 69 to 25 mM. Glutamic acid, taurine and beta-alanine were the most sensitive to hyposmolarity, followed by glycine, alanine and serine, whereas isoleucine, phenylalanine and valine were only weakly reactive. The properties of this osmolarity-sensitive release of amino acids were examined using 3H-taurine. Decreasing osmolarity to 85, 75 or 50% increased taurine efflux from 0.6% per min to 1.6, 3.5 and 5.06 per min, respectively. The time course of 3H-taurine release closely follows that of the regulatory volume decrease in MDCK cells. Taurine release was unaffected by removal of Na+, Cl- or Ca2+, or by treating cells with colchicine or cytochalasin. It was temperature dependent and decreased at low pH. Taurine release was unaffected by bumetanide (an inhibitor of the Na+/K+/2Cl- carrier); it was inhibited 16 and 67 by TEA and quinidine (inhibitors of K+ conductances), unaffected by gadolinium or diphenylamine-2-carboxylate (inhibitors of Cl- channels) and inhibited 50% by DIDS. The inhibitory effects of DIDS and quinidine were additive. Quinidine but not DIDS inhibited taurine uptake by MDCK cells.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗