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B Díaz

Publications and source records attributed to B Díaz.

At least 19 recordsLinked to original sources
PubMed2002

Age differences in neurokinin A and substance P from the hypothalamus, pituitary, pineal gland, and striatum of the rat. Effect of exogenous melatonin.

Previous data showed that aging of the central nervous system (CNS) is associated with widespread changes in tachykinin gene expression. However, there are no data about the possible role of exogenous melatonin in modulating the tachykinergic system during aging. The aim of this work was to analyze the age-dependent changes on neurokinin A (NKA) and substance P (SP) levels in hypothalamus, pituitary, pineal gland and striatum and the role of exogenous melatonin on these changes. We studied female rats at three different ages: 5-month-old (cyclic), 15-month-old (preacyclic) and 25-month-old (acyclic). Hypothalamic tachykinin levels increase when female rats reached acyclicity, this increase was blunted in acyclic-melatonin-treated rats. However, melatonin treatment in young cyclic rats resulted in significantly increased values as compared to controls. Pituitary NKA concentrations did no show age-dependent changes in control rats, however, in both, preacyclic and acyclic-melatonin-treated rats significantly increased values of pituitary NKA were found compared to controls. In the pineal gland, a marked decrease of NKA levels was observed in acyclic-control rats. Melatonin treatment did not alter this decrease. In the striatum, NKA and SP concentrations were significantly reduced in preacyclic- and acyclic-control rats compared to young cyclic rats, melatonin had no effect on striatal tachykinins. Our results indicate that melatonin may regulate tachykinin stores during aging mainly on structures of the neuroendocrine-reproductive axis.

Aging↗
PubMed2001

Hormone levels of world class cyclists during the Tour of Spain stage race.

OBJECTIVES: To evaluate the hormonal response to strenuous endurance exercise performed by elite athletes. METHODS: Nine professional cyclists (mean (SD) age 28 (1) years; mean (SD) VO(2)MAX 75.3 (2.3) ml/kg/min) who participated in a three week tour race (Vuelta a España 1999) were selected as subjects. Morning urinary levels of 6-sulphatoxymelatonin (aMT6s) and morning serum levels of testosterone, follicle stimulating (FSH), luteinising hormone (LH), and cortisol were measured in each subject at t(0) (before the competition), t(1) (end of first week), t(2) (end of second week), and t(3) (end of third week). Urine samples of aMT6s were also evaluated in the evening at t(0), t(1), t(2), and t(3). RESULTS: Mean urinary aMT6s levels had increased significantly (p<0.01) during the day after each stage (1091 (33) v 683 (68) ng/ml at t(1); 955 (19) v 473 (53) ng/ml at t(2); 647 (61) v 337 (47) ng/ml at t(3)). Both morning and evening aMT6s levels decreased significantly during the study. A similar pattern was observed for morning serum levels of cortisol and testosterone. CONCLUSIONS: The results suggest that the basal activity of the pineal gland, adrenal glands, and testis may be decreased after consecutive days of intense, long term exercise.

Adult↗
PubMed2000

Prenatal melatonin exposure affects luteinizing hormone and hypothalamic and striatal neuropeptide Y in the male rat offspring.

The present study examines the influence of prenatal melatonin on the hypothalamic and striatal neuropeptide Y (NPY) concentrations as well as on luteinizing hormone (LH) levels. Male rat offspring of control and melatonin treated mother rats were studied at different ages of the sexual development: infantile, prepubertal, pubertal and adult ages. Hypothalamic NPY levels were much higher during the juvenile than throughout the infantile period. After prenatal melatonin treatment significantly higher values since day 15 up to 35, also at 60 days of age were found, as compared with controls. Striatal NPY levels were lower than in hypothalamus. Again, NPY in the striatum from offspring of melatonin treated mother rats showed significantly higher values than the respective controls at most of the ages studied. However, prenatal melatonin exerted an inhibitory influence upon LH secretion pattern, since decreased concentrations up to 25 days of age and delayed peak values at pubertal age were observed. The present study also suggest that the effect of NPY upon LH secretion is related to sexual development, since NPY exerted opposite effect in infantile than in pubertal period and melatonin administration during intrauterine life prevented this effect.

Aging↗
PubMed2000

In vivo regulation of cell death by embryonic (pro)insulin and the insulin receptor during early retinal neurogenesis.

Programmed cell death is an established developmental process in the nervous system. Whereas the regulation and the developmental role of neuronal cell death have been widely demonstrated, the relevance of cell death during early neurogenesis, the cells affected and the identity of regulatory local growth factors remain poorly characterized. We have previously described specific in vivo patterns of apoptosis during early retinal neurogenesis, and that exogenous insulin acts as survival factor (Díaz, B., Pimentel, B., De Pablo, F. and de la Rosa, E. J. (1999) Eur. J. Neurosci. 11, 1624-1632). Proinsulin mRNA was found to be expressed broadly in the early embryonic chick retina, and decreased later between days 6 and 8 of embryonic development, when there was increased expression of insulin-like growth factor I mRNA, absent or very scarce at earlier stages. Consequently, we studied whether proinsulin and/or insulin ((pro)insulin) action in prevention of cell death has physiological relevance during early neural development. In ovo treatment at day 2 of embryonic development with specific antibodies against (pro)insulin or the insulin receptor induced apoptosis in the neuroretina. The distribution of apoptotic cells two days after the blockade was similar to naturally occurring cell death, as visualized by TdT-mediated dUTP nick end labeling. The apoptosis induced by the insulin receptor blockade preferentially affected to the Islet1/2 positive cells, that is, the differentiated retinal ganglion cells. In parallel, the insulin survival effect on cultured retinas correlated with the activation of Akt to a greater extent than with the activation of MAP kinase. These results suggest that the physiological cell death occurring in early stages of retinal development is regulated by locally produced (pro)insulin through the activation of the Akt survival pathway.

Animals↗
PubMed1999

Apoptotic cell death of proliferating neuroepithelial cells in the embryonic retina is prevented by insulin.

The role of programmed cell death is well established for connecting neurons. Conversely, much less is known about apoptosis affecting proliferating neuroepithelial cells. Chick retina from day 4 to day 6 of embryonic development (E), essentially proliferative, presented a defined distribution of apoptotic cells during normal in vivo development, as visualized by TdT-mediated dUTP nick end labelling (TUNEL). Insulin, expressed in the early chick embryonic retina as proinsulin, attenuated apoptosis in growth factor-deprived organotypic culture of E5 retina. This effect was demonstrated both by TUNEL and by staining of pyknotic nuclei, as well as by release of nucleosomes. Application of a 1 h [methyl-3H]thymidine pulse in ovo at E5, followed by organotypic culture in the presence or absence of insulin, showed that this factor alone decreased the degradation of labelled DNA to nucleosomes by 40%, as well as the proportion of labelled pyknotic nuclei. Both features are a consequence of apoptosis affecting neuroepithelial cells, which were in S-phase or shortly after. In addition, when the E5 embryos were maintained in ovo after the application of [methyl-3H]thymidine, 70% of the apoptotic retinal cells were labelled, indicating the in vivo prevalence of cell death among actively proliferating neuroepithelial cells. Apoptotic cell death is thus temporally and spatially regulated during proliferative stages of retinal neurogenesis, and embryonic proinsulin is presumably an endogenous protective factor.

Animals↗
PubMed1999

[Blood lead levels in children of Cordoba City].

Exposure to environmental lead is a major hazard to public health. International Environmental Agencies have assessed that blood lead concentrations of 10.0-15.0 micrograms/dl or even lower may be a risk factor for children. This survey focussed on environmental lead contamination and tried to provide information about blood lead levels in the children population of Cordoba City. A total of 172 children between 6 months and 9 years of age assisted in health centers and hospitals from December 1995 to December 1996 were surveyed. Lead assessment was performed by atomic absorption spectrophotometry with graphite furnace. Results revealed that 73.3% of the children population studied exhibited blood lead levels lower than 10.0 micrograms/dl; 19.2% evidenced risk concentration levels (10.0-14.9 micrograms/dl) and 7.6% showed concentrations higher than 15.0 micrograms/dl. It was confirmed that children with elevated concentrations lived in areas where numerous car repair shops are located. Three of the subjects lived in slums. From the group with low blood lead levels (< 10.0 micrograms/dl), 25 children lived downtown or near main avenues of heavy traffic and belonged to middle class families. Our survey showed a high occurrence of children with lead levels higher than 15.0 micrograms/dl (7.6%) whose etiology risk factors have been identified. Prevention should be able to cut down this occurrence through a safe control of environmental lead sources.

Argentina↗
PubMed1998

Heat shock proteins in retinal neurogenesis: identification of the PM1 antigen as the chick Hsc70 and its expression in comparison to that of other chaperones.

While the role of heat shock proteins under experimental stress conditions is clearly characterized, their expression in unstressed cells and tissues and their functions in normal cell physiology, besides their chaperone action, remain largely undetermined. We report here the identification in chicken of the antigen recognized by the monoclonal antibody PM1 [Hernández-Sánchez et al. (1994) Eur. J. Neurosci., 6,1801-1810] as the noninducible chaperone heat-shock cognate 70 (Hsc70). Its identity was determined by partial peptide sequencing, immuno-crossreactivity and two-dimensional gel-electrophoresis. In addition, we examined its expression during chick embryo retinal neurogenesis. The early widespread Hsc70 immunostaining corresponding to most, if not all, of the neuroepithelial cells becomes restricted to a subpopulation of these cells in the peripheral retina as development proceeds. On the other hand, retinal ganglion cells, differentiating in the opposite central-to-peripheral gradient, retained Hsc70 immunostaining. Other molecular chaperones, the heat-shock proteins Hsp40, Hsp60 and Hsp90, did not seem to compensate the loss of Hsc70. They also showed decreasing immunostaining patterns as neurogenesis proceeds, although distinctive from that of Hsc70, whereas Hsp70 was not detected in the embryonic retina. This precise cellular and developmental regulation of Hsc70, a generally considered constitutive molecular chaperone, in unstressed embryos, together with the expression of other chaperones, provides new tools and a further insight on neural precursor heterogeneity, and suggests possible specific cellular roles of chaperone function during vertebrate neurogenesis.

Adenosine Triphosphatases↗
PubMed1998

[Diarrhea associated with Clostridium difficile. One-year retrospective study at a tertiary hospital].

BACKGROUND: Diarrhea associated with Clostridium difficile is a health care problem of growing importance in the last few years specially in the hospital environment. The epidemiologic data and factors associated with this disease have not, to date, been sufficiently studied in Spain. METHODS: The cases of diarrhea associated with C. difficile reported in 1996 in a tertiary hospital of 1,500 beds were retrospectively reviewed, collecting clinical and epidemiologic data. The technique used for the detection of the C. difficile toxin was EIA Premier. RESULTS: One hundred thirty-two patients were included in the study, 83.3% of whom were over the age of 65 years, who had had 148 episodes of diarrhea associated with C. difficile. Most had been admitted into internal medicine (36%) or in the geriatric department (25%) and the remaining in the surgical departments (16.4%) or others (22.6%). The most frequently prescribed antibiotics were third generation cephalosporins (28.6%), clindamycin (17%), quinolones (11.1%) and macrolides (9.1%). Most of the patients received from 2 to 4 antibiotics prior to presenting diarrhea. Thirteen percent of the episodes of diarrhea associated with C. difficile were exclusively treated with withdrawal of the prescribed antibiotic, while the remaining cases were also given specific treatment which in 68.6% of the cases was with metronidazole and 31.4% with vancomycin. No significant difference was observed in the evolution of the patients according to the antibiotic prescribed. CONCLUSIONS: Diarrhea associated with C. difficile should be taken into account as a frequent complication of wide spectrum antibiotic treatment, specially in the elderly, immunosuppressed or in patients with pluripathology. With this study the authors wish to underline the need for the judicious use of antibiotics in the hospital environment and aid in the rapid diagnosis of this entity.

Adult↗
PubMed1995

Maternal pineal gland participates in prepubertal rats' ovarian oocyte development.

BACKGROUND: Sexual maturation is a very complex phenomenom that it is mediated by the ontogeny of the hypothalamus-pituitary-gonadal axis during intrauterine life. The maternal pineal gland can affect fetal development because the main pineal hormone, melatonin, crosses the placental barrier. We found that melatonin treatment during gestation in the rat produced delayed sexual maturation of the female offspring. The present work was undertaken to study the maturational stage of oocytes of prepubertal female rats when their mothers were either pinealectomized (PIN-X) or treated with melatonin (MEL) during pregnancy. METHODS: Three groups of female Wistar rats were used: control, PIN-X, and those treated (250 micrograms/100 g body weight) with melatonin throughout pregnancy. Ovaries of 25-30- and 34-day-old female offspring were studied during the prepubertal phase. Morphometric studies of semithin sections (1 micron) of the ovaries were performed. Oocyte, nuclear, and nucleolar volumes were calculated by a computer-assisted program (M.I.P.) in an image analyzer Kontron. Regularity of the structures was determined by the frequency distributions of circular and regular form factors. RESULTS: Cytometric study of oocyte structure showed a frequency distribution of regular and circular form factors, with a high degree of regularity very close to unit. Cellular and nuclear volumes of follicular oocytes showed a transitory increase at 30 days of age in control rats. In the offspring of MEL-treated mother rats, a pattern of oocyte development showed significantly lower nuclear and nucleolar volumes at 30 days of age than at the other time points and significantly lower cellular volume at 34 days of age than at 25 days of age. In the offspring of PIN-X mother rats, no significant differences in oocyte cellular volumes were observed throughout prepubertal development, but we observed a significantly higher nuclear volume at 25 days of age and a significantly lower nucleolar volume at 30 days of age. CONCLUSIONS: These findings show that the maternal pineal gland participates in cellular and nuclear volumes of prepubertal oocyte development. Melatonin treatment during pregnancy resulted in a redirected postnatal oocyte development.

Animals↗