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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
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↗
PubMed2001

Phagocytic function in cyclists: correlation with catecholamines and cortisol.

Flow cytometer measurements were made of the basal variations in peripheral blood functional monocytes and granulocytes over the course of a training season (January to November) of a cycling team. Parallel determinations were made of plasma concentration of catecholamines (chromatography) and cortisol (RIA) in a search for neuroendocrine markers. The results showed the greatest phagocytic capacity to occur in the central months (March, May, and July), coinciding with the greatest number and highest level of competitive events with good correlation with a peak in epinephrine during these months (r(2) = 0.998 for monocytes and r(2) = 0.674 for granulocytes). No good correlations were found between phagocytosis and norepinephrine or cortisol. The highest values for phagocytosis and epinephrine concentration were found in May. These results suggest that blood epinephrine concentration could be a good neuroendocrine marker of sportspeople's phagocytic response.

Adult↗
PubMed2001

Protective role of melatonin against MPTP-induced mouse brain cell DNA fragmentation and apoptosis in vivo.

OBJECTIVES: 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is a neurotoxin that induces a Parkinsonian-type syndrome in animals which is similar to Parkinson's disease in humans. MPTP toxicity partially depends on the production of free radicals which in turn play a key role in the apoptotic death of neurons. In the present study melatonin, a potent free radical scavenger with antiapoptotic properties, was given to determine whether it would reduce oxidative stress in mice treated with MPTP. MATERIALS AND METHODS: Male mice were given MPTP with or without melatonin and the brain was studied either 6h, 24h, 7 days or 15 days after the last MPTP injection. RESULTS: The results show that melatonin counteracted in vivo MPTP-induced apoptosis in midbrain neurons at 6 and 24 h after MPTP treatment, and partially prevented apoptosis at 7 and 15 days after MPTP administration. MPTP treatment also produced time-dependent cell damage, whereas melatonin reduced the percentage of damaged cells at all time points, the effect being most evident at 15 days after treatment. Moreover, melatonin counteracted MPTP-dependent DNA fragmentation in the midbrain and striatum at 7 and 15 days after drug administration. CONCLUSION: These results support a role for melatonin in protecting neurons against MPTP toxicity in vivo, and suggest that its antiapoptotic action is one of the mechanisms by which melatonin protects neuronal cells from neurotoxic insults.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed2001

Different patterns in the histology and autofluorescence of the Harderian glands of the Syrian Hamster, rat, mouse, Mongolian gerbil and guinea pig.

The purpose of this study was to compare the natural fluorescence in the Harderian glands of the Syrian hamster, rat, mouse, Mongolian gerbil and guinea pig (both sexes). For each species, 10 animals (five males and five females) were used. Histological autofluorescence studies were performed using a fluorescence microscope (450-490 nm filter). Two different types of fluorescent cells were observed in both hamster (type AFI high intensity and type AFII, low fluorescence) and rat (type AFI, low fluorescence and type AFII, high fluorescence) Harderian glands. The fluorescence was basally located in all mice cells, whereas it was observed near the epithelial cell nuclei in the Mongolian gerbil (occupying two-thirds and one-third of the cells in males and females, respectively). A high intensity of fluorescence was present throughout the acinar cells in the guinea pig. The patterns of fluorescence identified exhibited a sexual dimorphism in all species studied. These results demonstrate that the Harderian glands of the animal species examined exhibit a variety of histological autofluorescence patterns.

Animals↗
PubMed2000

Protective effect of beta-carbolines and other antioxidants on lipid peroxidation due to hydrogen peroxide in rat brain homogenates.

Tryptoline and pinoline are two beta-carbolines isolated from the nervous system of mammals. We investigated the ability of these compounds to prevent lipid peroxidation induced by hydrogen peroxide in rat brain homogenates. We also compared their effects with other known antioxidants including melatonin, trolox and ascorbic acid. Lipid peroxidation was assessed by measuring malonaldehyde (MDA) and 4-hydroxy-alkenals (4-HDA) concentrations in the brain homogenates. Incubation with hydrogen peroxide (5 mM) increased MDA+4-HDA levels, which were totally prevented by tryptoline, pinoline, melatonin and trolox in a concentration-dependent manner. By contrast, higher MDA-4-HDA concentrations compared with control experiments were found after incubation with ascorbic acid, thus reflecting an increase of lipid peroxidation induced by this compound. Although in vivo studies are needed, the data suggest that these beta-carbolines may be potential neuroprotective agents because of their antioxidant activities.

Aldehydes↗
PubMed2000

Changes with aging in the modulation of macrophages by norepinephrine.

The effect of aging on the norepinephrine (NE)-induced modulation of phagocytic and oxygen-dependent microbicidal processes of mouse peritoneal macrophages was studied. Phagocytosis of latex beads on culture plates and superoxide anion production was evaluated in young (12 weeks), adult (22 weeks), mature (48 weeks) and old (72 weeks) BALB/c mice after in vitro incubation with 10(-12), 10(-9), 10(-7), 10(-5) or 10(-3) M concentrations of NE. The results indicate that the phagocytic response to NE is quite similar in young and mature mice, with increased phagocytosis after incubation with 10(-7) and 10(-3) M, and decreased phagocytosis with 10(-5) M. Macrophages from adult mice increased their phagocytic capacity after incubation with the highest concentrations of NE (10(-5) and 10(-3) M) and macrophages from old animals only were stimulated with 10(-3) M. In addition, it was found that usually NE increased the extracellular superoxide anion production in the absence of phagocytosis in adult mice. No statistically significant changes were found in intracellular superoxide anion levels, but an increase was seen after phagocytosis in macrophages from adult, mature and old animals, especially after incubation with 10(-5) M. In conclusion, the results obtained indicate that the modulation of macrophages by NE does not only depend on the concentration of this neurotransmitter, but also on age.

Aging↗
PubMed2000

Structure, functioning, and assembly of the ATP synthase in cells from patients with the T8993G mitochondrial DNA mutation. Comparison with the enzyme in Rho(0) cells completely lacking mtdna.

The structure and functioning of the ATP synthase of human fibroblast cell lines with 91 and 100%, respectively, of the T8993G mutation have been studied, with MRC5 human fibroblasts and Rho(0) cells derived from this cell line as controls. ATP hydrolysis was normal but ATP synthesis was reduced by 60% in the 100% mutants. Both activities were highly oligomycin-sensitive. The levels of F(1)F(0) were close to normal, and the enzyme was stable. It is concluded that the loss of ATP synthesis is because of disruption of the proton translocation step within the F(0) part. This is supported by membrane potential measurements using the dye JC-1. Cells with a 91% mutation load grew well and showed only a 25% loss in ATP synthesis. This much reduced effect for only a 9% difference in mutation load mirrors the reduced pathogenicity in patients. F(1)F(0) has been purified for the first time from human cell lines. A partial complex was obtained from Rho(0) cells containing the F(1) subunits associated with several stalk, as well as F(0) subunits, including oligomycin sensitivity conferring protein, b, and c subunits. This partial complex no longer binds inhibitor protein.

Adenosine Triphosphate↗
PubMed2000

Genotoxicity of paraquat: micronuclei induced in bone marrow and peripheral blood are inhibited by melatonin.

The ability of melatonin to influence paraquat-induced genotoxicity was tested using micronucleated polychromatic erythrocytes as an index of damage in both bone marrow and peripheral blood cells of mice. Melatonin (10 mg/kg) or an equal volume of saline were administered intraperitoneally (ip) to mice 30 min prior to an ip injection of paraquat (20 mg/kgx2), and thereafter at 6-h intervals until the conclusion of the study (72 h). The number of the micronucleated polychromatic erythrocytes increased after paraquat administration both in peripheral blood and bone marrow cells. Melatonin administration to paraquat-treated mice significantly reduced micronuclei formation in both peripheral blood and bone marrow cells; these differences were apparent at 24, 48 and 72 h after paraquat administration. The induction of micronuclei was time-dependent with peak values occurring at 24 and 48 h. The reduction in paraquat-related genotoxicity by melatonin is likely due in part to the antioxidant activity of the indole. We did not observe effects of melatonin over paraquat in paraquat+melatonin groups incubated at 0, 60 and 120 min. Mitomycin C, which was used as a positive control, also caused the expected large rises in micronuclei in both bone marrow and peripheral blood cells at 24, 48 and 72 h after its administration.

Animals↗
PubMed2000

5-methoxytryptophol preserves hepatic microsomal membrane fluidity during oxidative stress.

Lipid peroxidation is a degenerative chain reaction in biological membranes that may be initiated by exposure to free radicals. This process is associated with changes in the membrane fluidity and loss of several cell membrane-dependent functions. 5-methoxytryptophol (ML) is an indole isolated from the mammalian pineal gland. The purpose of this study was to investigate the effects of ML (0. 01mM-10mM) on membrane fluidity modulated by lipid peroxidation. Hepatic microsomes obtained from rats were incubated with or without ML (0.01-10 mM). Then lipid peroxidation was induced by FeCl(3), ADP, and NADPH. Membrane fluidity was determined using fluorescence spectroscopy. Malonaldehyde (MDA) +4-hydroxyalkenals (4-HDA) concentrations were estimated as an indicator of the degree of lipid peroxidation. With oxidative stress, membrane fluidity decreased and MDA+4-HDA levels increased. ML (0.01-3 mM) reduced membrane rigidity and the rise in MDA+4-HDA formation in a concentration-dependent manner. 10 mM ML protected against lipid peroxidation but failed to prevent the membrane rigidity. In the absence of oxidative reagents, ML (0.3-10 mM) decreased membrane fluidity whereas MDA+4-HDA levels remained unchanged. This indicates that ML may interact with membrane lipids. The results presented here suggest that ML may be another pineal indoleamine (in addition to melatonin) that resists membrane rigidity due to lipid peroxidation.

Aldehydes↗
PubMed2000

Horizontal transmission of Amblyospora albifasciati García and Becnel, 1994 (Microsporidia: amblyosporidae), to a copepod intermediate host and the neotropical mosquito, Aedes albifasciatus (Macquart, 1837).

The life cycle of Amblyospora albifasciati is characterized by three sporulation sequences involving the definitive mosquito host and a copepod intermediate host. Meiospores of A. albifasciati were infectious per os to adult females of the copepod Mesocyclops annulatus. All developmental stages in the copepod had unpaired nuclei, with sporulation involving the formation of a sporontogenic interfacial envelope and the production of a second type of uninucleate spore. These spores, formed in the ovaries of M. annulatus, were large, pyriform, and measured 10.4 x 4.8 microm. They infected Aedes albifasciatus larvae when ingested to initiate a sequence that involves schizogony and gametogony and ends with plasmogamy and nuclear association to form diplokaryotic meronts. Oval binucleate spores (9.3 x 3.1 microm) are formed in the adult mosquito and are responsible for vertical transmission to the filial generation.

Aedes↗