Biomedical subjects

J Galvez

Publications and source records attributed to J Galvez.

At least 19 recordsLinked to original sources

PubMed2003

Factors associated with time to sputum smear conversion in active pulmonary tuberculosis.

OBJECTIVE: To ascertain the factors affecting the time between the initiation of treatment and obtaining three negative sputum smears. DESIGN: In a study of 109 patients with pulmonary tuberculosis, the main variable was the period during which the patients had sputum smears once treatment was initiated. Multivariate analysis (multiple linear regression) was performed to document those variables independently associated with time to conversion. RESULTS: The patients had positive smears for a mean of 28.63 days. The most frequent radiographic pattern was cavitary disease (36.7%). HIV co-infection was present in 38.5% of the patients. HIV-infected patients showed a cavitation pattern in only 9.6% vs 52.2% of patients without HIV infection (P < 0.001). The variables that showed a statistically significant and independent relationship with the time to sputum smear conversion were pulmonary radiographic pattern, age and erythrocyte sedimentation rate (ESR). CONCLUSIONS: ESR, age and the presence of cavitary disease seem to be factors associated with a longer time to sputum smear conversion in patients with active pulmonary tuberculosis. However, HIV co-infection is associated with a shorter time to sputum conversion. A key factor is therefore the presence or not of cavitation, independently of HIV infection.

Adult↗

PubMed2000

Anti-toxoplasma activities of 24 quinolones and fluoroquinolones in vitro: prediction of activity by molecular topology and virtual computational techniques.

The apicoplast, a plastid-like organelle of Toxoplasma gondii, is thought to be a unique drug target for quinolones. In this study, we assessed the in vitro activity of quinolones against T. gondii and developed new quantitative structure-activity relationship models able to predict this activity. The anti-Toxoplasma activities of 24 quinolones were examined by means of linear discriminant analysis (LDA) using topological indices as structural descriptors. In parallel, in vitro 50% inhibitory concentrations (IC(50)s) were determined in tissue culture. A multilinear regression (MLR) analysis was then performed to establish a model capable of classifying quinolones by in vitro activity. LDA and MLR analysis were applied to virtual structures to identify the influence of each atom or substituent of the quinolone ring on anti-Toxoplasma activity. LDA predicted that 20 of the 24 quinolones would be active against T. gondii. This was confirmed in vitro for most of the quinolones. Trovafloxacin, grepafloxacin, gatifloxacin, and moxifloxacin were the quinolones most potent against T. gondii, with IC(50)s of 0.4, 2.4, 4.1, and 5.1 mg/liter, respectively. Using MLR analysis, a good correlation was found between measured and predicted IC(50)s (r(2) = 0.87, cross-validation r(2) = 0.74). MLR analysis showed that the carboxylic group at position C-3 of the quinolone ring was not essential for anti-Toxoplasma activity. In contrast, activity was totally dependent on the presence of a fluorine at position C-6 and was enhanced by the presence of a methyl group at C-5 or an azabicyclohexane at C-7. A nucleophilic substituent at C-8 was essential for the activity of gatifloxacin and moxifloxacin.

4-Quinolones↗

PubMed2000

Ventricular mass and diastolic function in patients infected by the human immunodeficiency virus.

OBJECTIVE: Echocardiographic and Doppler analysis of myocardial mass and diastolic function in patients infected with HIV. DESIGN: Case-control study. SETTING: Tertiary referral centre, Huelva, Spain. PATIENTS: 61 asymptomatic patients with HIV infection and 32 healthy controls. MAIN OUTCOME MEASURES: Time motion, cross sectional, and Doppler echocardiographic studies were performed, and left ventricular mass and diastolic function variables determined (peak velocity of early and late mitral outflow and isovolumic relaxation time). RESULTS: Left ventricular mass index (LVMI) was decreased in patients compared with healthy controls (mean (SD): 76.7 (23.6) v 118.8 (23.5) g/m(2), p < 0.001). Linear regression analysis showed a correlation between LVMI and brachial fat and muscle areas. The ratio of peak velocities of early and late mitral outflow was decreased in HIV infected patients compared with controls (1.19 (0.44) v 1.58 (0.38), p < 0.001). This ratio was exclusively related to haemodynamic variables (heart rate, systolic and diastolic blood pressures). HIV infected patients had a prolonged isovolumic relaxation time (103.0 (10.5) v 72.9 (12.9) ms, p < 0.001). Isovolumic relaxation time was correlated only with brachial muscle area on multivariate analysis. CONCLUSIONS: HIV infected patients had a reduced left ventricular mass index and diastolic functional abnormalities. These cardiac abnormalities are predominantly related to nutritional status.

Adult↗

PubMed1999

Antioxidant potential of evening primrose oil administration in hyperlipemic rabbits.

The dietary intake of saturated fatty acids affects arteriosclerosis. We studied the effect of supplementation (15% wt/wt) of a hyperlipemic diet (1.33% cholesterol) with evening primrose oil (EPO) (Oenothera biennis) for 6 weeks in four groups of 10 rabbits each. At the end of this period we determined lipid peroxidation, glutathione content, and glutathione peroxidase, reductase and transferase activities in liver, brain, heart, aorta and platelets. The atherogenic diet increased tissue lipid peroxidation and decreased the protective antioxidant effect of glutathione. Dietary supplementation with EPO reduced tissue lipid peroxidation (61% in liver, 57% in brain, 42% in heart, 24% in aorta, 33% in platelets). Total glutathione was increased, especially in the aorta (90%) and platelets (200%); however, in all tissues the percentage of oxidised glutathione decreased. Evening primrose oil reduced glutathione peroxidase activity and increased the activities of glutathione reductase and transferase. We conclude that in rabbits made hyperlipemic with a diet rich in saturated fatty acids, EPO decreased tissue oxidative stress.

Animals↗

PubMed1997

Determination of parameters that characterize effector-target conjugation of human NK and LAK cells by flow cytometry.

Effector-target conjugation between different cell populations of human NK cells and K562 tumor cells has been studied from binding isotherms obtained from data of effector (alpha) and target (beta) conjugate frequencies measured by flow cytometry analysis at different effector-to-target ratios. Non-linear and linear regression methods were applied to these isotherms to calculate the binding parameters that characterize the process of conjugation, namely, the maximum effector and target conjugate frequencies, the dissociation constant of the conjugates formed, the binding units and the area under the binding isotherms. The results obtained show that: (1) flow cytometry analysis of effector-target conjugation is faster, unbiased and more suitable than microscopic counting of conjugates, thereby permitting the analysis of larger number of conjugates in shorter times, (2) the binding parameters derived from conjugate frequencies obtained by flow cytometry analysis differ from those obtained by microscopy, (3) the discrepancies between the two methods are due to the presence of several cells engaged in multicellular conjugates that are detected as single particles by flow cytometry and (4) the analysis of population distributions of the conjugates formed at different values of the effector-to-target ratio permit the above discrepancies to be corrected.

Flow Cytometry↗

PubMed1996

Conjugation between cloned human NK cells (H7.8) and K562/MOLT4 tumor cell systems: saturability, binding parameters, and population distribution of conjugates.

Effector-target conjugation between cloned NK(H7.8)-K562 and NK(H7.8)-MOLT4 tumor cells has been studied from binding isotherms. Nonlinear and linear regression methods were used to calculate the maximum effector and target conjugate frequencies as well as the dissociation constant of the conjugates formed. The results obtained show there is an enhancement of the effector-target saturability and effector-target affinity in comparison with the values previously observed for polyclonal NK effector cells. Population distributions revealed that different types of conjugates were formed as the effector-to-target ratio was changed in the NK(H7.8)-K562 and NK(H7.8)-MOLT4 tumor cells. In both cases conjugates where one effector cell was bound to several target cells and conjugates with one target cell bound to several effector cells were found. At all values of R the prevailing conjugates were those with one effector cell bound to one target cell.

Cell Communication↗

PubMed1996

Computer simulation and data analysis of effector-target interactions: the extraction of binding parameters from effector and target conjugate frequencies data by using linear and nonlinear data-fitting transformations.

Binding isotherms for effector-target conjugation when effector conjugate frequencies are measured by holding constant the number of effector cells and by varying the number of target cells are characterized by two parameters, the maximum effector conjugate frequency, alpha max, and gamma, which is related to the dissociation constant of the conjugates formed, K d. The suitability of four linear transformations of these binding isotherms, as well as nonlinear data-fitting techniques, to provide estimates of alpha max and gamma is discussed. The strength and weakness of these procedures were investigated by calculating alpha max and gamma from different sets of 100 or 500 replicate "experiments," which were generated by using an algorithm that provides noise contributions to the conjugate frequencies with gaussian distributed errors. Both unweighted and weighted data points were used in these calculations. A similar analysis can also be performed for binding isotherms in which target conjugate frequencies are measured at different values of effector cells by holding constant the number of target cells. In this case, the binding isotherms are characterized by two parameters, the maximum target conjugate frequency, beta max, and delta, which is also related to K d. The results obtained demonstrate that if the experimental conditions are chosen properly, linear transformations and nonlinear fitting techniques provide reliable estimates for the binding parameters. Not all procedures, however, provide estimates with the same accuracy, and special emphasis to this fact must be given if the binding assays are performed at low values of the number of effector cells.

Algorithms↗

PubMed1996

Adhesion, invasion and intracellular replication of Salmonella typhimurium in a murine hepatocyte cell line. Effect of cytokines and LPS on antibacterial activity of hepatocytes.

Elimination of pathogenic microorganisms in the liver may be an important effector mechanism in host defenses. In this paper we describe the adhesion, invasion and multiplication of Salmonella typhimurium in a murine embryonic hepatocyte cell line (ATCC TIB-73). Monolayers of hepatocytes treated with recombinant IFN gamma, IL1 beta, and LPS exhibit antibacterial activity against intracellular Salmonella. The dynamic of the infection process in stimulated vs unstimulated hepatocytes was determined by counting the number of survival bacteria in the cell monolayers at 4 and 28h after gentamicin was added to the infected cells. Salmonella typhimurium is able to adhere, invade and replicate inside the hepatocytes. The maximum number of cell-associated bacteria is approximately 15 bacteria per cell, whereas the invasive capacity of Salmonella is 0.003 bacteria per hepatocyte. Stimulated cultures display antibacterial activity compared to unstimulated controls. The antibacterial activity does not seem to be mediated by nitric oxide (NO) since inhibition of NO production by using NG-Monomethyl-L-Arginine did not revert the antibacterial activity. Also, high amounts of NO induced by adding L-Arginine to the cell cultures did not enhance hepatocyte antibacterial activity.

Animals↗

PubMed1995

The derivation of binding parameters from effector and target conjugate frequency data using linear and non-linear data-fitting transformations. Application of such transformations to the NK-MOLT4 and NK-K562 effector-target systems.

Effector-target conjugation is described quantitatively by binding isotherms which are characterized by three parameters, the maximum effector and target conjugate frequencies, alpha max and beta max, and the dissociation constant of the conjugates formed, KD. In this paper the application of non-linear data-fitting techniques, as well as linear transformations of the binding isotherms that permit us to use standard regression analysis, has been tested to calculate estimates of these parameters in the NK-MOLT4 and NK-K562 effector-target systems. Both unweighted and weighted data were used to calculate alpha max, beta max and KD for six different donors which were used as a source of NK cells. The results obtained have shown that these regression methods are useful for revealing potential disparities between binding efficiencies in effector-target systems.

Adult↗

PubMed1995

Flavonoid inhibition of enzymic and nonenzymic lipid peroxidation in rat liver differs from its influence on the glutathione-related enzymes.

Eight flavonoids were tested for their antiperoxidative activities against lipid peroxidation induced in liver cell membranes either by nonenzymic way (ascorbic acid-Fe2+ system, FeAs) or by enzymic way (arachidonic acid, AA). When lipid peroxidation is induced by FeAs, the order in the inhibitory potency for the different flavonoids assayed is: (-)-epicatechin approximately luteolin > quercetin approximately (+)-catechin > delphinidin > kaempferol >> apigenin > naringenin. However, when lipid peroxidation is induced by AA, the potency order is markedly modified: delphinidin > (-)-epicatechin > (+)-catechin > kaempferol > quercetin > luteolin > naringenin > apigenin. These flavonoids were also tested for their influence on glutathione-related enzymes, which constitute one of the aim physiological antioxidant systems. It is concluded that the antiperoxidative effect shown by most of the flavonoids is exerted without modifying these enzymes.

Animals↗

PubMed1994

Binding units (BU) and the area under binding isotherms (AUI). New indices of effector-target conjugation.

New methods for simplified quantitation of effector-target conjugation have been developed. The binding unit (BU) is defined as the number of target cells required to bind a specified percentage of effector cells. The number of binding units is determined from binding isotherms in which effector conjugate frequencies are measured by holding constant the number of effector cells and by varying the number of target cells. Alternately, a binding unit can be defined as the number of effector cells required to bind a specified percentage of target cells. In this case, BU is computed from binding isotherms in which target conjugate frequencies are measured at different values of effector cells by holding constant the number of target cells. Also, the area under the curve (AUI) of these isotherms is another index that can be used as an overall measure of the binding capacity in an effector-target system. The experimental values of BU and AUI determined from effector and target isotherms agree well with theoretical predictions based on our previously developed binding model (J. Immunol. Methods (1992) 155, 133-147). The relationship between BU and AUI, and procedures to determine these parameters are shown. The value of these indices to express effector-target conjugation quantitatively has been confirmed by determining the values of BU and AUI for the NK-K562 effector-target system.

Adult↗

PubMed1994

Oral administration of quercitrin modifies intestinal oxidative status in rats.

1. Oral administration of quercitrin to rats for 3 days increases the mucosal glutathione contents in ileum and colon as well as inhibits non-enzymatic lipid peroxidation induced in membrane fractions from jejunal and colonic mucosa. 2. After 7 days of treatment with quercitrin, rat intestinal oxidative status trends to normalize to control rats.

Administration, Oral↗

PubMed1993

Antidiarrhoeic activity of Euphorbia hirta extract and isolation of an active flavonoid constituent.

The antidiarrhoeic activity of the Euphorbia hirta whole plant was investigated. The lyophilized decoction demonstrated antidiarrhoeic activity in experimental models of diarrhoea induced by castor oil, arachidonic acid, and prostaglandin E2. It showed no activity when magnesium sulphate was used to provoke the diarrhoea. The lyophilized decoction delayed small intestinal transit when this was accelerated by castor oil but not in normal conditions. A flavonoid, quercitrin, with antidiarrhoeic activity was isolated from this crude drug.

Animals↗

PubMed1993

Anti-inflammatory activity of the essential oil of Bupleurum fruticescens.

The essential oil of Bupleurum fruticescens was investigated qualitatively and quantitatively by GC and GC-MS analyses. The anti-inflammatory activity of the whole essential oil and its major components was also investigated in the rat hindpaw edema model induced by carrageenin or by PGE1. The anti-inflammatory activity shown by the essential oil can be attributed to the two major components, alpha-pinene and beta-caryophyllene. In order to know the role of the adrenal glands in the anti-inflammatory activity exerted by the two major components of the essential oil, they were studied against the carrageenin-induced hindpaw edema in adrenolectomized rats. It is concluded that alpha-pinene needs the integrity of the adrenal glands to exert its anti-inflammatory activity, as opposed to beta-caryophyllene which was also active in adrenolectomized animals.

Animals↗

PubMed1992

Effector-target interactions: saturability, affinity and binding isotherms. A study of such interactions in the human NK cell-K562 tumour cell system.

Effector-target interactions at the cell-to-cell level have been studied. This has revealed that saturability, i.e., the existence of a finite number of specific receptor sites, applies to both the effector and target cell populations and plays a key role in the formation of conjugates. As a result, two maximum conjugate frequencies, alpha max and beta max, are recognised for the effector and target cell populations, respectively. The dissociation constant of the conjugates formed, KD, characterizes effector-target affinity. This constant, together with the maximum conjugate frequencies, are the three parameters which make it possible to describe the binding process quantitatively. The existence of binding isotherms for effector-target interactions has been demonstrated. These isotherms contain all the relevant information necessary to interpret quantitatively the formation of conjugates. Quantitative procedures to determine the three binding parameters are described together with the modifications necessary to use Scatchard plots in the analysis of conjugate frequencies in these kinds of cell-to-cell interactions. A quantitative study of these interactions in the NK-K562 tumour cell system has been performed. For this purpose, nine different cell source donors were used to test the model proposed. Relationships with related phenomena--CMC and the adhesion process--are also discussed.

Adult↗

PubMed1989

Model for population distributions of lymphocyte-target cell conjugates.

A quantitative model for the population distributions of the different types of conjugates formed between cytotoxic T lymphocytes and target cells has been developed. The comparison of the theoretical predictions with data of the literature reveals that the transit populations among the different types of conjugates depends on the lymphocyte-to-target ratio, R, and two constants, k and k1. These constants (where k greater than k1) govern, respectively, the transit populations among conjugates of the type LTi (LTn----LTn-1----...LT), and among LjT conjugates (LT----L2T----...----LmT). We have found that high ratios are necessary to obtain conjugates where multiple T lymphocytes are bound to one target cell, and that under these conditions the predominant conjugate, LjT, varies according to j = 1 + k1R. Conversely, for low values of R the predominant population is of the type LTi, where i also shows a linear dependence on R. Our model explains also why the conjugate LT is normally the predominant population under the experimental conditions reported in the literature. A discussion of the influence exerted by the population distributions of lymphocyte-target cell conjugates on the kinetic of the lytic process for these kinds of effector-target systems has also been made.

Immunity, Cellular↗

PubMed1989

Effect of conjugate size on the kinetics of cell-mediated cytotoxicity at the population level.

We developed a model for the kinetics of target cell lysis by cytotoxic T-lymphocytes which accounts for most facts observed at the population level. In contrast to previous models, the following facts: conjugate frequency of cytotoxic T-lymphocytes bound to target cell, dependence of this frequency on the lymphocyte-to-target ratio (R), variation of R with time as target cells are destroyed, and population distributions of the different types of conjugates formed between lymphocytes and target cells, which are involved in the kinetics of these kinds of effector-target systems have been contemplated in the model. The relationship with effector-kinetic analogy models for the lytic process has been discussed. Predictions of the model have been explored and compared with experimental observations about target cell lysis reported in the literature.

Cytotoxicity, Immunologic↗

PubMed1989

Airway obstruction, palatal vault formation and malocclusion: a cross-sectional study.

A cross-sectional study of one thousand and sixty-five children (508 boys and 557 girls) from the Watertown School System was done in order to determine whether there is a relationship between airway obstruction, palatal vault formation and malocclusion. The age range was 5 to 12 years old with a mean age of 8.5 years. Breathing pattern was based on the lip competency (seal) of each individual. The height of the palatal vault, the Angle's molar classification, cuspid relationship, the anterior and posterior cross-bites, the deep-bites or open-bites were also recorded. Enlarged tonsils were observed and the presence of allergies was noted. High palatal vaults were observed in children with lip incompetency (85.8%), and in children with Class II (73.6%) and Class III (65.3%). Anterior and/or posterior cross-bites accompanied high palatal vaults. From the examined children in this study, 20% presented known allergies. Eighty (80%) percent of the allergic children had high palatal vaults. Enlarged tonsils were also found in children with high palatal vaults.

Airway Obstruction↗