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Biomedical subjects

J J García

Publications and source records attributed to J J García.

At least 19 recordsLinked to original sources
PubMed2006

Epizootiological studies of Amblyospora camposi (Microsporidia: Amblyosporidae) in Culex renatoi (Diptera: Culicidae) and Paracyclops fimbriatus fimbriatus (Copepoda: Cyclopidae) in a bromeliad habitat.

The epizootiology of Amblyospora camposi was studied in a natural population of Culex renatoi, a bromeliad-inhabiting mosquito, and its intermediate host, Paracyclops fimbriatus fimbriatus, over a 2-year period. Twenty Eryngium cabrerae plants were sampled monthly from January 2003 to January 2005 and the prevalence of A. camposi in P.f. fimbriatus and Cx. renatoi populations was determined. The monthly prevalence rates of meiospore infections in Cx. renatoi larvae never exceeded 5.5% and was detected in 50% of the monthly samples. Meiospores were available in plants over the course of the study at a mean concentration of 2 x 10(4) meiospores/ml. Within each plant the parasite was maintained by horizontal transmission. P.f. fimbriatus with vegetative stages and mature spores were found regularly in bromeliads suggesting efficient meiospore infectivity to field copepod populations. The mean concentration of spores from copepods found in plants was 8 x 10(2) spores/ml. Infections in copepods were detected in 54% of the monthly samples with a prevalence rate ranging from 0.55 to 17.4% and an overall average of 5.1%. Vegetative stages in fourth instar mosquito larvae (probably derived from the horizontal pathway via spores formed in copepods) were detected in 12.5% of the monthly samples with an overall prevalence rate of 1.1%. Infections in female and male adults were detected in 20.8% of the monthly samples with an overall average of 4.1% and 6.8%, respectively.

Amblyospora↗
PubMed2006

Role of Hsp72 and norepinephrine in the moderate exercise-induced stimulation of neutrophils' microbicide capacity.

The influence of a single session of moderate exercise (45 min at 55% of VO(2 )max) performed by young sedentary men (23-25 years old) on the microbicidal capacity of neutrophils was compared by using both direct (killing of phagocytosed Candida albicans) and indirect (superoxide anion production measured by NBT reduction) techniques. In addition, the role of norepinephrine and heat shock protein (Hsp) 72 in the modulation of microbicide capacity of neutrophils was evaluated during the protocol of exercise and recovery period (24 h). No significant changes were found in the superoxide production after exercise. However, immediately after exercise there was an increase in the destruction of C. albicans, which remained higher than basal values 1 day later. This behaviour was similar to the changes found in the serum extracellular Hsp72 concentrations (an increase after exercise that remained higher than basal values 24 h later). In vitro, the raised physiological concentration of Hsp72 after exercise also increased the microbicide capacity of neutrophils with respect to controls and the values induced by the basal concentration of the protein. This indicates that Hsp72 is participating as a "stress mediator" of the stimulated microbicide activity during moderate exercise. However, norepinephrine is not mediating the increased killing of C. albicans during exercise.

Adult↗
PubMed2006

Protective effect of melatonin and pinoline on nitric oxide-induced lipid and protein peroxidation in rat brain homogenates.

Nitric oxide (NO) is a physiological neurotransmitter, a mediator of the excitatory neurotransmitter glutamate pathways that regulates several neuroendocrine functions, but excessive NO is toxic by itself and it interacts with superoxide radical (O(2)(-)) to form the peroxynitrite anion (ONOO(-)). Using rat brain homogenates, we investigated the effects of melatonin and pinoline in preventing the level of lipid peroxidation (LPO) and carbonyl contents in proteins induced by nitric oxide (NO) which was released by the addition of sodium nitroprusside (SNP). Lipid and protein peroxidation were estimated by quantifying malondialdehyde (MDA) and 4-hydroxyalkenal (4-HDA) concentrations and carbonyl contents, respectively. SNP increased MDA+4-HDA and carbonyl contents production in brain homogenates in a time and concentration dependent manner. Both, melatonin and pinoline reduced NO-induced LPO and carbonyl contents in a dose-dependent manner in concentrations from 0.03 to 3 mM and 1 to 300 microM, respectively. Under the in vitro conditions of this experiment, both antioxidants were more efficient in limiting SNP protein oxidation than lipid damage.

Animals↗
PubMed2006

The number of CD34(+) cells in peripheral blood as a predictor of the CD34(+) yield in patients going to autologous stem cell transplantation.

The number of CD34(+) cells in peripheral blood (PB) is a guide to the optimal timing to harvest peripheral blood progenitor cells (PBPC). The objective was to determine the number of CD34(+) cells in PB that allows achieving a final apheresis product containing > or =1.5 x 10(6) CD34(+) cells/kg, performing up to three aphereses. Between March 1999 and August 2003, patients with hematological and solid malignancies who underwent leukapheresis for autologous bone marrow transplantation were prospectively evaluated. Seventy-two aphereses in 48 patients were performed (mean 1.45 per patient; range 1-3). PBPC were mobilized with cyclophosphamide plus recombinant human granulocyte-colony stimulating factor (G-CSF) (n = 40), other chemotherapy drugs plus G-CSF (n = 7), or G-CSF alone (n = 1). We found a strong correlation between the CD34(+) cells count in peripheral blood and the CD34(+) cells yielded (r = 0.903; P < 0.0001). Using receiver-operating characteristic (ROC) curves, the minimum number of CD34(+) cells in PB to obtain > or =1.5 x 10(6)/kg in the first apheresis was 16.48 cells/microL (sensitivity 100%; specificity 95%). The best cut-off point necessary to obtain the same target in the final harvest was 15.48 cells/microL, performing up to three aphereses (sensitivity 89%; specificity 100%). In our experience, > or =15 CD34(+) cells/microL is the best predictor to begin the apheresis procedure. Based on this threshold level, it is possible to achieve at least 1.5 x 10(6)/kg CD34(+) cells in the graft with < or =3 collections.

Adolescent↗
PubMed2006

Altered beta-amyloid precursor protein isoforms in Mexican Alzheimer's Disease patients.

OBJECTIVE: To determine the beta-amyloid precursor protein (betaAPP) isoforms ratio as a risk factor for Alzheimer's Disease and to assess its relationship with demographic and genetic variables of the disease. METHODS: Blood samples from 26 patients fulfilling NINCDS-ADRDA diagnostic criteria for AD and 46 healthy control subjects were collected for Western blotting for betaAPP. A ratio of betaAPP isoforms, in optical densities, between the upper band (130 Kd) and the lower bands (106-110 Kd) was obtained. Odds ratios were obtained to determine risk factor of this component. RESULTS: betaAPP ratio on AD subjects was lower than that of control subjects: 0.3662 +/- 0.1891 vs. 0.6769 +/- 0.1021 (mean +/- SD, p<0.05). A low betaAPP ratio (<0.6) showed an OR of 4.63 (95% CI 1.45-15.33). When onset of disease was taken into account, a betaAPP ratio on EOAD subjects of 0.3965 +/- 0.1916 was found vs. 0.3445 +/- 0.1965 on LOAD subjects (p>0.05). CONCLUSIONS: Altered betaAPP isoforms is a high risk factor for Alzheimer's disease, although it has no influence on the time of onset of the disease.

Aged↗
PubMed2004

Norepinephrine as mediator in the stimulation of phagocytosis induced by moderate exercise.

During intensive exercise the stimulation of phagocytosis is mediated by "stress hormones". During moderate exercise, however, such mediation is less clear. The influence of moderate exercise (45 min at 55% maximal oxygen uptake) on the phagocytic capacity of neutrophils was evaluated in sedentary men. The exercise stimulated phagocytosis of Candida albicans, and the stimulation was maintained for at least 24 h. The possible neuroendocrine mediators were then investigated. Stimulation of phagocytosis was found after incubating neutrophils from sedentary individuals, who were in a basal state, with plasma from exercised individuals. Immediately after exercise, there was a significant increase in the concentration of norepinephrine, but not of epinephrine or cortisol. Incubation of neutrophils with this post-exercise physiological concentration of norepinephrine also stimulated phagocytosis, and the effect was blocked by both propranolol and phentolamine. The norepinephrine-augmented phagocytosis was accompanied by an increase in intracellular levels of cAMP, but not of cGMP or calcium. In conclusion, moderate exercise performed by sedentary people stimulates the phagocytic capacity of neutrophils, and the stimulation lasts for at least 24 h. Norepinephrine mediates the stimulation, although other mechanisms could be involved during the recovery period.

Adult↗
PubMed2004

Host range and specificity of an Argentinean isolate of the aquatic fungus Leptolegnia chapmanii (Oomycetes: Saprolegniales), a pathogen of mosquito larvae (Diptera: Culicidae).

An isolate from Argentina of the fungal mosquito pathogen Leptolegnia chapmanii (ARSEF 5499), was tested against 12 species of mosquito larvae and on species of non-target aquatic invertebrates and vertebrates. The mosquito species tested were Aedes aegypti, Anopheles sp., Culex apicinus, Cx. castroi, Cx. dolosus, Cx. pipiens, Cx. renatoi, Isostomyia paranensis, Ochlerotatus albifasciatus, Oc. crinifer, Psorophora cyanescens, and P. ferox. Mosquito larvae of 10 species were susceptible, with mortality rates from 10-100%. Two mosquito species Cx. renatoi and I. paranensis were not infected by Leptolegnia. None of the non-target fauna treated was infected by L. chapmanii with exception of members of the Family Chironomidae which were susceptible at low infection rates.

Animals↗
PubMed2004

Scanning electron microscopy of the superficial pineal gland of the 15-day-old rat (Rattus norvegicus).

The presence of a cortex and medulla in the superficial pineal gland has been a controversial point in the morphology of this structure in mammals. The published reports indicate contradictory data especially in rodents. In this study the pineal gland of 15-day-old male rats (Rattus norvegicus) were studied, using scanning electron microscopy, in an attempt to determine whether or not a cortex and medulla are apparent in the pineal gland of young rats. The superficial pineal gland of the 15-day-old rat exhibited both a cortex and a medulla; these areas exhibited different structural organizations. The cortex had a thickness of 40-80 microm and the cells did not show a particular arrangement. The center of the gland was composed of a medulla, which had a width of 1000-1200 microm, and consisted of cells arranged in cords; its morphology was distinctly different from that of the cortex.

Animals↗
PubMed2002

Melatonin improves deferoxamine antioxidant activity in protecting against lipid peroxidation caused by hydrogen peroxide in rat brain homogenates.

Deferoxamine (DF) is an antioxidant molecule because of its ability to chelate iron. This study compared the ability of DF alone or in combination with melatonin, 5-methoxytryptophol or pinoline in preventing lipid peroxidation due to hydrogen peroxide (H(2)O(2)) in rat brain homogenates. Malondialdehyde (MDA) and 4-hydroxyalkenals (4-HDA) in the homogenates were measured as indices of lipid peroxidation. Incubation of homogenates with DF reduced, in a dose-dependent manner, MDA+4-HDA formation due to H(2)O(2). When melatonin, 5-methoxytryptophol or pinoline were added to the incubation medium, the efficacy of DF in preventing lipid peroxidation was enhanced. These cooperative effects between DF, melatonin, and related pineal products may be important in protecting tissues from the oxidative stress due to iron overload.

Animals↗
PubMed2002

Therapeutic effects of psyllium in type 2 diabetic patients.

OBJECTIVE: The aim of this study was to evaluate the effects of psyllium in type 2 diabetic patients. DESIGN: The study included three phases: phase 1 (1 week), phase 2 (treatment, 14 g fibre/day, 6 weeks) and phase 3 (4 weeks). At the end of each phase a clinical evaluation was performed after the ingestion of a test breakfast of 1824.2 kJ (436 kcal). Measurements included concentrations of blood glucose, insulin, fructosamine, GHbA(1c), C-peptide and 24 h urinary glucose excretion. In addition, uric acid, cholesterol and several mineral and vitamin concentrations were also evaluated. SETTING: The study was performed at the Department of Pharmacology, Toxicology and Nursing at the University of León (Spain). SUBJECTS: Twenty type 2 diabetic patients (12 men and 8 women) participated in the study with a mean age of 67.4 y for men and 66 y for women. The mean body mass index of men was 28.2 kg/m(2) and that of women 25.9 kg/m(2). RESULTS: Glucose absorption decreased significantly in the presence of psyllium (12.2%); this reduction is not associated with an important change in insulin levels (5%). GHbA(1c), C-peptide and 24 h urinary glucose excretion decreased (3.8, 14.9 and 22.5%, respectively) during the treatment with fibre (no significant differences) as well as fructosamine (10.9%, significant differences). Psyllium also reduced total and LDL cholesterol (7.7 and 9.2%, respectively, significant differences), and uric acid (10%, significant difference). Minerals and vitamins did not show important changes, except sodium that increased significantly after psyllium administration. CONCLUSIONS: The results obtained indicate a beneficial therapeutic effect of psyllium (Plantaben) in the metabolic control of type 2 diabetics as well as in lowering the risk of coronary heart disease. We also conclude that consumption of this fibre does not adversely affect either mineral or vitamin A and E concentrations. Finally, for a greater effectiveness, psyllium treatment should be individually evaluated.

Aged↗
PubMed2002

In-vitro study of the effect of adrenaline on the functional capacity of human neutrophils: role during exercise.

We studied the effect of adrenaline on the capacity of human neutrophils to attach, ingest and destroy Candida albicans. The neutrophils were incubated in vitro in the presence of an adrenaline concentration taken as basal (10-10 m), and another that is referred to as being reached following physical exercise (10-9 m). Two higher concentrations (10-7 m and 10-5 m), which are seldom attained in blood but which can occur at specific locations in the organism, were tested as having a possible pharmacological application. At the two high concentrations (10-7 m and 10-5 m), the capacity to attach, ingest and destroy C. albicans was greater than at the physiological concentrations (10-10 m and 10-9 m). Indeed, the capacity to attach and ingest C. albicans was significantly less after incubation with these physiological concentrations than the control values (incubation in the absence of adrenaline). Hence, high concentrations of adrenaline seem to enhance neutrophils' phagocytic capacity compared to physiological plasma concentrations, whereas small variations such as those caused by physical exercise have no effect on this functional capacity.

Adolescent↗
PubMed2001

Insulin receptor binding to erythrocytes during normal pregnancy: an update of the method.

Normal values of the parameters of insulin receptors in erythrocytes were provided to make a control group throughout gestation, 24 h postpartum and six weeks after delivery with the aim of comparing them with other parameters with insulin receptor-related pathologies. Thus, one of the purposes of this study was the update of a method to calculate the parameters of insulin receptors in erythrocytes, carrying out several modifications that improved the assay: during binding studies incubation was in continuous rotation shaking, and increasing maximal insulin binding. Other modifications were the increase in the concentration of insulin 125I to 1 ng/mL, and the maximal concentration of unlabeled insulin, 100 ng/mL. Erythrocyte age was considered by the intracellular creatine content providing control values and allowing the normalization of the parameters of insulin receptor during gestation. Data obtained in this study indicated that changes at receptor binding level may be also considered to explain insulin resistance: week 28 showed maximal insulin secretion (16.70+/-1.44 microU/mL) whereas plasma glucose concentrations remained almost constant (91.14+/-2.37 mg/100 mL) with respect to the 1st and 2nd trimester of pregnancy (89.73+/-1.38 and 91.71+/-2.10 mg/100 mL respectively); insulin reached the point of maximal resistance, which is explained by a decrease of maximum specific insulin binding, %Bo (6.32+/-0.51) at minimal values due to a decrease of high-affinity receptor number per erythrocyte, N-AA (16+/-2) at minimal values. Moreover, the negative correlation between progesterone (31.2+/-0.2 ng/mL) and Ka-AA (r=-0.71) could possibly be related to this maximal resistance.

Adult↗
PubMed2001

N-acetylserotonin suppresses hepatic microsomal membrane rigidity associated with lipid peroxidation.

N-acetylserotonin, the immediate precursor of melatonin in the tryptophan metabolic pathway in the pineal gland, has been reported to be an antioxidant. The aim of this work was to test the effect of N-acetylserotonin in stabilizing biological membranes against oxidative stress. Hepatic microsomal membranes from male adult rats were incubated with N-acetylserotonin (0.001-3 mM) before inducing lipid peroxidation using FeCl(3), ADP and NADPH. Control experiments were done by incubating microsomal membranes with N-acetylserotonin in the absence of lipid peroxidation-inducing drugs. Membrane fluidity was assessed by fluorescence spectroscopy and malonaldehyde plus 4-hydroxyalkenals concentrations were measured to estimate the degree of lipid peroxidation. Free radicals induced by the combination of FeCl(3)+ADP+NADPH produced a significant decrease in the microsomal membrane fluidity, which was associated with an increase in the malonaldehyde plus 4-hydroxyalkenals levels. These changes were suppressed in a concentration-dependent manner when N-acetylserotonin was added in the incubation buffer. In the absence of lipid peroxidation, N-acetylserotonin (0.001-3 mM) did not change membrane fluidity nor malonaldehyde plus 4-hydroxyalkenals levels. These results suggest that the protective role of N-acetylserotonin in preserving optimal levels of fluidity of the biological membranes may be related to its ability to reduce lipid peroxidation.

Aldehydes↗
PubMed2001

[Prevalence of osteoporosis assessed by densitometry in the Spanish female population].

BACKGROUND: Osteoporotic fractures represent an important clinic and socioeconomic problem. Although it is well known the incidence of fractures in Spain, we do not know how many persons are at risk. The World Health Organization (WHO) has approved a densitometric criteria to define osteopenia (OSPE) and osteoporosis (OSP). The aim of this study has been to evaluate the prevalence of OSP and OSPE in women of the Spanish population. SUBJECTS AND METHOD: With the data of a study of bone mass in the Spanish population, stratified according to age, using dual-energy X-ray absortiometry (DXA) with a QDR/1000 Hologic device and according the WHO criteria, we have calculated the prevalence of OSP and OSPE in normal Spanish women at the lumbar spine (LS) and/or femoral neck (FN). RESULTS: The prevalence of osteoporosis at LS is: 0.34% in the group aged 20-44 years; 4.31% in the group aged 45-49 years; up to 9.09% in the group aged 50-59 years; 24.29% in the 60-69 years, and 40.0% in the group aged 70-79 years. The overall prevalence of osteoporosis is 11.13%, confidence interval (CI) 95% from 9.4 to 12.8%. The prevalence of osteoporosis at FN is: 0.17% in the group aged 20-44 years, 0% in the 45-49 years, up to 1.3% in the 50-59 years, 5.71% in the 60-69 years and 24.24% in the group aged 70-79 years. The overall prevalence of osteoporosis is 4,29% (CI 95% 3.2-5.4%). The prevalence in female older than 50 years was 22.8% at LS and 9.1% at FN. 12.73% of Spanish women population has osteoporosis at LS or FN, which represent about 1,974,400 women; 2.68% of total population has osteoporosis in both sites. CONCLUSIONS: Even we do not include in this study women with established osteoporosis (with fractures), the number of Spanish women with osteoporosis is very high.

Absorptiometry, Photon↗
PubMed2001

Characterization of the protective effects of melatonin and related indoles against alpha-naphthylisothiocyanate-induced liver injury in rats.

The protective effect of melatonin, 6-hydroxymelatonin and N-acetylserotonin against alpha-naphthylisothiocyanate (ANIT)-induced liver injury was investigated and compared in rats injected once with the hepatotoxicant (75 mg/kg body weight). In rats injected with ANIT alone, liver injury with cholestasis developed within 24 h, as indicated by both serum levels of alanine aminotransferase (SGPT) and aspartic acid aminotransferase (SGOT) activities and serum total bilirubin concentration. The administration of melatonin or 6-hydroxymelatonin (10 mg/kg body weight) to ANIT-injected rats reduced significantly the serum levels of both SGPT and SGOT and the serum total bilirubin concentration. For all hepatic biochemical markers, melatonin was more effective that 6-hydroxymelatonin. By comparison, the administration of N-acetylserotonin (10 mg/kg body weight) to ANIT-injected rats did not reduce the serum levels of either hepatic enzymes or the serum total bilirubin concentration. In ANIT-injected rats, hepatic lipid peroxidation (LPO) was significantly higher than in control animals and this increase was significantly reduced by either melatonin, 6-hydroxymelatonin or N-acetylserotonin. Furthermore, ANIT treatment caused a significant reduction in liver microsomal membrane fluidity and this reduction was completely reversed by the three indoles. The liver from ANIT-injected rats showed several histopathological alterations; above all there was an acute infiltration of polymorphonuclear neutrophils and an increase in the number of apparent apoptotic hepatocytes. The concurrent administration of melatonin reduced the severity of all morphological alterations, specially the neutrophil infiltration and the number of presumed apoptotic cells. On the contrary, the administration of 6-hydroxymelatonin or N-acetylserotonin did not provide any protective effect in terms of the histopathological alterations. These results indicate that melatonin protects against ANIT-induced liver injury with cholestasis in rats, and suggests that this protective effect is likely due to its antioxidant properties and above all to its capacity to inhibit liver neutrophil infiltration, a critical factor in the pathogenesis of ANIT-induced liver injury. 6-hydroxymelatonin, although able to provide partial protection against the ANIT-induced hepatic injury, probably through its antioxidant properties by mechanisms that are unclear, was unable to reduce neutrophil infiltration. Finally, N-acetylserotonin in the experimental conditions of this study, only exhibited some antioxidant protection but had no protective effect against ANIT-induced hepatic damage.

1-Naphthylisothiocyanate↗