Biomedical subjects

F Aguado

Publications and source records attributed to F Aguado.

At least 19 recordsLinked to original sources

PubMed2002

NasoNet, modeling the spread of nasopharyngeal cancer with networks of probabilistic events in discrete time.

The spread of cancer is a non-deterministic dynamic process. As a consequence, the design of an assistant system for the diagnosis and prognosis of the extent of a cancer should be based on a representation method that deals with both uncertainty and time. The ultimate goal is to know the stage of development of a cancer in a patient before selecting the appropriate treatment. A network of probabilistic events in discrete time (NPEDT) is a type of Bayesian network for temporal reasoning that models the causal mechanisms associated with the time evolution of a process. This paper describes NasoNet, a system that applies NPEDTs to the diagnosis and prognosis of nasopharyngeal cancer. We have made use of temporal noisy gates to model the dynamic causal interactions that take place in the domain. The methodology we describe is general enough to be applied to any other type of cancer.

Artificial Intelligence↗

PubMed2001

Behavior of phalangeal bone ultrasound in normal women with relation to gonadal status and body mass index.

The behavior of phalangeal bone ultrasound was studied, measured by amplitude-dependent speed of sound (Ad-SOS) in meters per second, in 324 normal women (mean age 48.9 +/- 13.7 years) classified by gonadal status (premenopausal, perimenopausal and postmenopausal) and body mass index (BMI, thin, normal, overweight and obese). Ad-SOS differed significantly with gonadal status and BMI (p<0.0001 for all). In the overall group of women, Ad-SOS correlated negatively with age (r=-0.84, p<0.0001), weight (r=-0.16, p<0.005), BMI (r=-0.27, p<0.0001), and tartrate-resistant acid phosphatase concentration (TRAP) (r=-0.35, p<0.0001). The negative correlation remained significant in the groups separated by gonadal status, but to a lesser extent. After adjusting for confounding variables such as age and weight, Ad-SOS was dependent on age (but not on weight or BMI) in the overall group of women and in the gonadal status groups. In conclusion, Ad-SOS values differed significantly with gonadal status and BMI, and correlated negatively with TRAP. The plot of Ad-SOS against age differed significantly with gonadal status as well as BMI.

Acid Phosphatase↗

PubMed2001

Cysteine string proteins are associated with cortical granules of Xenopus laevis oocytes.

Cysteine string proteins (csps) are associated with secretory organelles in a wide range of eukaryotic cells. Functional studies of these proteins indicate that they subserve one or more vital steps in the pathway of regulated exocytosis. Here, we document the presence of csps in fully grown (stage VI) oocytes of the frog, Xenopus laevis. Both Northern and immunoblot data support the conclusion that csps are expressed in these cells. In addition, immunoreactive csp is seen even at the earliest stage of oocyte development, namely, in stage I oocytes. Finally, immunoblot and immunocytochemical results indicate that csps are associated with cortical granules of stage II-VI oocytes. These observations suggest that csps participate in the cortical reaction that underlies the sustained block to polyspermy in Xenopus eggs. Moreover, because of the relative ease of manipulating cells as large as Xenopus oocytes, this system harbors considerable promise as a model for studying the role of csps and other proteins in exocytotic events.

Animals↗

PubMed2001

Differences in tissue fatty acid composition between reared and wild sharpsnout sea bream, Diplodus puntazzo (Cetti, 1777).

The fatty acid composition and lipid content of white muscle, liver and mesenteric fat, in reared v. wild sharpsnout sea bream (Diplodus puntazzo) were compared. The mesenteric fat index fat weight/body weight) and the lipid contents of both white muscle and liver proved consistently higher in farmed v. wild sharpsnout sea bream (79.0 (SE 13.1) v. 38.7 (SE 5.1) g/kg, 188.4 (SE 30.0) v. 58.2 (SE 3.9) g/kg and 27.2 (SE 3.7) v. 17.3 (SE 1.9) g/kg, respectively). The higher values of linoleic, eicosapentaenoic, docosahexaenoic and n-3 series acids in reared fish muscle make reared sharpsnout more favourable for human consumption. In reared fish mesenteric fat, polyunsaturated fatty acids reached higher levels (32.54 (SE 0.71) g/100 g total fatty acids than those found in wild fish (26.08 (SE 1.38) g/100 g total fatty acids or even present in the diet (28.34 g/100 g total fatty acids). Compared with cultured fish, wild sharpsnout displayed a higher content of n-3 fatty acids in liver fat (31.67 (SE 1.13) g/100 g total fatty acids), but lower in mesenteric fat (20.35 (SE 1.41) g/100 g total fatty acids). Atherogenic index values were similar for wild and reared fish in all tissues, while the index of thrombogenicity of muscle and mesenteric fat (0.353 (SE 0.012) and 0.402 (SE 0.021) respectively) was significantly increased in wild fish probably due to the omnivorous habits of the species and/or to seasonal food variations. Depending on the time of the year or the season, reared fish could be more suitable for human consumption than wild fish.

Animals↗

PubMed2000

Aberrant development of hippocampal circuits and altered neural activity in netrin 1-deficient mice.

Diffusible factors, including netrins and semaphorins, are believed to be important cues for the formation of neural circuits in the forebrain. Here we have examined the role of netrin 1 in the development of hippocampal connections. We show that netrin 1 and its receptor, Dcc, are expressed in the developing fimbria and in projection neurons, respectively, and that netrin 1 promotes the outgrowth of hippocampal axons in vitro via DCC receptors. We also show that the hippocampus of netrin 1-deficient mice shows a misorientation of fiber tracts and pathfinding errors, as detected with antibodies against the surface proteins TAG-1, L1 and DCC. DiI injections show that hippocampal commissural axons do not cross the midline in these mutants. Instead, when axons approach the midline, they turn ventrally and form a massive aberrant projection to the ipsilateral septum. In addition, both the ipsilateral entorhino-hippocampal and the CA3-to-CA1 associational projections show an altered pattern of layer-specific termination in netrin 1-deficient mice. Finally, optical recordings with the Ca(2+) indicator Fura 2-AM show that spontaneous neuronal activity is reduced in the septum of netrin 1-mutant mice. We conclude that netrin 1 is required not only for the formation of crossed connections in the forebrain, but also for the appropriate layer-specific targeting of ipsilateral projections and for the control of normal levels of spontaneous neural activity.

Animals↗

PubMed1999

Localization and expression of Jun-like immunoreactivity in apoptotic neurons induced by colchicine administration in vivo and in vitro depends on the antisera used.

The expression of members of the Jun family of transcription factors was examined by immunohistochemistry, Western blotting, in situ hybridization and Northern blotting in the developing and adult rat brain following colchicine administration. Apoptotic cells, as revealed by their typical morphology and positive staining with the method of in situ end-labeling of nuclear DNA fragmentation, were restricted to granule cells of the dentate gyrus and olfactory bulb, and a few cells in the upper layers of the entorhinal cortex in adult rats, whereas widespread apoptosis occurred in developing rats after colchicine administration. No modifications in the expression of Jun D and Jun B, except for a generalized and moderate Jun B expression in glial cells, were observed in colchicine-treated rats. Generalized and strong c-jun mRNA induction and c-Jun/AP-1 (Ab-1) protein expression was observed in the cerebral neocortex, entorhinal and piriform cortices, CAI and CA3 areas of the hippocampus and granule cell layer of the dentate gyrus in adult treated rats, thus indicating a generalized c-Jun response to colchicine administration. In contrast, c-Jun/AP-1 (N) and c-Jun/AP-1 (Ab-2) immunoreactivity was restricted to apoptotic cells in colchicine-treated adult and developing brains. Western blots of hippocampal homogenates and total brain homogenates in adult and developing rats, respectively, demonstrated a band of 39 kDa for the c-Jun/AP-1 (Ab-1) antibody in control animals, the intensity of which increased in colchicine-treated rats. However, a band of 37 kDa, the intensity of which also increased following colchicine administration, was observed for the c-Jun/AP- (N) and c-Jun/AP- (Ab-2) antibodies. Selective c-Jun/AP-1 (N) and c-Jun/AP-1 (Ab-2) expression was also observed in apoptotic cells of the SH-SY5Y neuroblastoma line after the addition of colchicine to the culture medium. Taken together, the present in vivo and in vitro results indicate a generalized c-Jun response to colchicine in sensitive cells, whereas the antibodies c-Jun/AP- (N) and c-Jun/AP-1 (Ab-2) recognize vulnerable cells dying via apoptosis.

Aging↗

PubMed1999

Fra-1 immunoreactivity in the rat brain during normal postnatal development and after injury in adulthood.

Fra-1 is a member of the Fos family whose functional role in the central nervous system is little understood. In the present study, Fra-1 immunoreactivity is examined in the rat brain during normal development and after different injuries in adulthood, by using Western blotting and immunohistochemistry. Western blots show a band at p35 which corresponds to the molecular weight of Fra-1. During postnatal development, Fra-1 immunoreactivity is observed in nerve fibers of all the main fiber tracts in the cerebrum, whereas Fra-1 immunoreactivity in adult rats is restricted to the hippocampus, mainly the molecular layer of the dentate gyrus and the mossy fiber layer. After administration of colchicine, an axonal transport inhibitor, Fra-1 immunoreactivity accumulates in the perikarya of many cerebral neurons, including those of the dentate gyrus, hippocampus, cerebral cortex, amygdala and thalamus. Fra-1 immunoreactivity is also found in the nuclei of reactive astrocytes, as revealed with double-labeling immunohistochemistry to Fra-1 and GFAP, following either intraperitoneal injection of kainic acid at convulsant doses, intrastriatal injection of quinolinic acid, or intraventricular injection of colchicine. These results suggest a cytoplasmic role for Fra-1 in the neurons, whereas the localization of Fra-1 in the nuclei of reactive astrocytes suggests a participation of this transcription factor in the activation of the AP-1 sequence of selected genes in the early glial response after different brain lesions.

Aging↗

PubMed1999

Syntaxin 1A and 1B display distinct distribution patterns in the rat peripheral nervous system.

Syntaxin 1 has been shown to play an outstanding role in synaptic vesicle exocytosis. Two isoforms of this protein are expressed in neurons, syntaxin 1A and 1B. However, the physiological significance of the occurrence of such closely related isoforms is not still understood. Here, by means of isoform-specific immunocytochemistry, we show that syntaxin 1A and 1B display different patterns of expression in the rat peripheral nervous system. Nerve terminals of sensory neurons reaching the spinal cord were clearly enriched in immunoreactive syntaxin 1A. Both isoforms were detected in cell bodies of sensory neurons at the dorsal root ganglia, although specific immunolabelling displayed very different patterns at the cellular level. Motor endplates and muscle spindles were only immunostained for syntaxin 1B. Syntaxin 1A was mainly associated with nerve fibres reaching small blood vessels. In addition, nerve plexuses of the enteric nervous system showed immunostaining for both syntaxin isoforms. The different distribution pattern of the two neuronal syntaxin isoforms in the rat peripheral nervous system could be related to isoform-specific biochemical properties involved in the exocytotic process.

Animals↗

PubMed1999

Colchicine administration in the rat central nervous system induces SNAP-25 expression.

he arrest of axonal transport by colchicine administration has been extensively used in immunocytochemical studies to increase the levels of neuroactive compounds in neuronal somata. In order to study the accumulation rates of a variety of proteins with location and physiological action at the synaptic terminal, we analysed, by immunocytochemical methods, the neuronal cell body content of these synaptic proteins in colchicine-injected rats. In sham-injected animals, all synaptic proteins tested were essentially observed in nerve fibres and terminal boutons. After colchicine administration, intense SNAP-25 immunoreactivity was found in many neuronal cell bodies throughout the CNS. In contrast, immunostaining for the rest of the synaptic proteins analysed (syntaxin 1A and 1B, synaptobrevin I and II, Rab3A, synaptophysin, synapsin I, synaptotagmin I and GAP-43) was virtually absent in neuronal cell bodies in treated animals. Furthermore, northern blot and in situ hybridization analysis revealed an increase in SNAP-25a and SNAP-25b messenger RNA isoforms in the brains of adult colchicine-administered animals. In addition, colchicine administration in five-day-old rat pups induced a notable increase in both SNAP-25 transcript isoforms. The present results indicate that in vivo colchicine administration, under conditions known to inhibit axoplasmic transport, upregulates SNAP-25 expression in the rat brain.

Animals↗

PubMed1999

Impact of weight in obese subjects on bone speed of sound.

RATIONALE AND OBJECTIVES: The authors determined the effect of obesity on measurements of amplitude-dependent speed of bone ultrasound (Ad-SOS [m/sec]) and compared them to the total body bone mineral content (TBBMC/g). METHODS: A total of 25 women were studied (mean age 41.8 +/- 10.2 years). In all the subjects, body mass index (BMI) exceeded 30 kg/m2 (range, 31.12-47.47 kg/m2); mean body weight was 104 +/- 17 kg. Ad-SOS was measured at the proximal phalanges and TBBMC in whole body with dual-energy x-ray absorptiometry. RESULTS: Correlation study (Fisher's r to z) showed that Ad-SOS correlated negatively with weight (r = -0.85, P < 0.0001) and with TBBMC (r = -0.71, P < 0.0001). The correlation between TBBMC and weight was r = 0.76, P < 0.0001. Body fat percentage correlated partially with TBBMC (r = 0.40, P < 0.05) and negatively with Ad-SOS (r = -0.75, P < 0.0001). When the correlation test was adjusted for weight (partial correlation), the correlation between Ad-SOS and TBBMC was not significant (r = -0.21, P = NS), and the correlation between Ad-SOS and weight continued to be inversely significant (r = -0.67, P < 0.0001). CONCLUSIONS: The results showed a clearly negative effect of weight on Ad-SOS measurements and indicated the limitations of this technique when employed in overweight and obese patients. Broad-band ultrasound attenuation and speed of sound, two commonly measured variables in bone ultrasound studies, may be differently affected by soft tissue.

Absorptiometry, Photon↗

PubMed1999

Exocytotic protein components in rat pituitary gland after long-term estrogen administration.

Recently, a set of proteins involved in the docking and fusion machinery of secretory organelles has been identified in anterior pituitary cells. In this study we analyzed, by Western blotting and immunocytochemistry, the expression of several proteins involved in exocytosis after long-term administration of 17beta-estradiol (E2) in Fischer 344 rats. No differences were observed in the amount of synaptosomal-associated protein of 25 kDa, synaptobrevin 2, syntaxin 1, synaptotagmin I and Rab3a in total brain homogenates from treated rats after E2 administration. In striking contrast, the levels of all of these exocytotic proteins, including cellubrevin, were notably decreased in pituitary glands of E2-treated rats. In addition, no differences were observed in the in vitro basal and 8-Br-cAMP-induced prolactin (PRL) release between pituitary cells from control and E2-treated rats, whereas TRH-induced PRL release in anterior pituitary cells from E2-treated animals was higher than in control donors. In conclusion, this study shows that protein components of the exocytotic machinery are specifically down-regulated in the pituitary gland of E2-treated Fischer 344 rats.

Animals↗

PubMed1998

Trk neurotrophin receptor family immunoreactivity in rat and human pituitary tissues.

Several lines of evidence suggest that neurotrophins may be involved in pituitary function. By immunocytochemical methods we analyzed the cellular distribution of their functional receptors in the pituitary gland. In the rat pituitary gland Trks were differentially distributed. Punctate immunoreactivity for TrkA was observed within the neural lobe, whereas numerous nerve endings were immunostained for TrkB and TrkC in the intermediate lobe. Endocrine cells of the intermediate lobe exhibited intense immunoreactivity for the three Trks, whereas scattered endocrine cells of the anterior lobe displayed a robust immunostaining for TrkC. In addition, TrkA and TrkB immunoreactivity was located in normal and neoplastic endocrine cells from human pituitary adenomas. The differential distribution of Trks in the hypophysis suggests a potential role of different neurotrophins in pituitary functions.

Adenoma↗

PubMed1998

TrkA immunoreactivity in reactive astrocytes in human neurodegenerative diseases and colchicine-treated rats.

It has been shown that nerve growth factor (NGF) administration is capable of curbing tissue damage in several neurodegenerative disorders. As a first step to learning about the possible functional role of NGF in the astroglial response during neurodegeneration, we have analyzed the expression of the functional receptor for NGF, TrkA, in human neurodegenerative diseases which are accompanied by reactive astrocytosis, as well as in human astrocytomas. We have compared these results with those observed in reactive astrocytes following colchicine-induced cellular damage to adult rats. In the human brain, strong TrkA immunoreactivity is observed in reactive astrocytes in a number of unrelated diseases, including Alzheimer's disease, Huntington's disease, progressive supranuclear palsy, multiple sclerosis, Creutzfeldt-Jakob disease, multifocal leukoencephalopathy and residual hypoxic encephalopathy. Neoplastic astrocytes in grade II and III astrocytomas display strong TrkA immunoreactivity. In the rat brain, reactive astrocytes following mechanical needle injury and colchicine administration show strong TrkA immunoreactivity. The presence of TrkA receptors in reactive astrocytes from different human neurodegenerative diseases and experimentally induced models in rats, and in neoplastic astrocytes suggests that NGF may participate in the astroglial response to different types of injury and neoplastic proliferation. Since astroglial cells are capable of producing NGF, it is plausible that this neurotrophin may function as an autocrine or paracrine factor in TrkA-expressing reactive and neoplastic glial cells.

Animals↗

PubMed1998

Ultrasonographic bone velocity in pregnancy: a longitudinal study.

OBJECTIVE: Longitudinal changes in bone mass were evaluated with use of ultrasonography and bone remodeling markers in 40 normal pregnant women in relation to their calcium intake. STUDY DESIGN: The study took place at the University of Alcalá Hospital in Madrid. Biochemical markers of bone remodeling and ultrasonographic bone propagation velocity in the proximal phalanxes of fingers 2 to 5 were measured in all three trimesters of pregnancy. Wilcoxon, unpaired and paired t tests, and analysis of variance were used. RESULTS: Ultrasonographic bone propagation velocity (meters per second) was lower in the second and third trimesters of pregnancy (p < 0.0001) compared with the respective preceding trimesters and in the third trimester in the overall group of pregnant women. Tartrate-resistant acid phosphatase and alkaline phosphatase levels increased significantly (p < 0.0001) in parallel with the ultrasonographic bone propagation velocity decrease. CONCLUSIONS: Gestation was accompanied by a reduction in ultrasonographic bone propagation velocity that was greater in women with low calcium intake.

Acid Phosphatase↗

PubMed1998

Synaptobrevin isoforms in secretory granules and synaptic-like microvesicles in anterior pituitary cells.

A set of synaptic proteins have been shown to be essential for the life cycle and exocytosis of synaptic vesicles at the nerve terminal. Recently, these proteins have also been identified in certain endocrine cells. Here we analysed the presence and location of some of these synaptic proteins in anterior pituitary cells. Immunoblotting data demonstrated that Rab3a, synaptotagmin, cellubrevin, synaptobrevin 2, syntaxin 1, SNAP-25 and synaptophysin were well represented in anterior pituitary cells as well as in the corticotroph cell line AtT-20. Cellubrevin was the most abundant synaptobrevin isoform present in pituitary cells. Moreover, both cellubrevin and synaptobrevin 2 took part of a protein complex involved in the fusion process in adenohypophyseal cells. Immunocytochemical and subcellular fractionation showed that cellubrevin, synaptobrevin 2, Rab3a and synaptotagmin were located in both secretory granules and synaptic-like microvesicles fractions. In contrast, SNAP-25 and syntaxin 1 were mainly associated with plasma membrane fractions. Therefore, these results suggest similar secretory mechanisms for synaptic vesicles and secretory organelles in both neuronal and endocrine cells.

Animals↗

PubMed1998

Neuroendocrine and immunocytochemical demonstrations of decreased hypothalamo-pituitary-adrenal axis responsiveness to restraint stress after long-term social isolation.

We have studied the effects of long-term social isolation of male Wistar rats, after early weaning (16 days), on the activity of the hypothalamo-pituitary-adrenal (HPA) axis. In addition to studying basal HPA activity, the response of the HPA axis to 15 min of immobilization stress was examined. Plasma corticosterone concentrations were measured, and the relative weights of adrenal glands, thymus, and testes were obtained, the latter to check whether gonadal function was affected by the isolation paradigm. Moreover, we carried out a quantitative immunohistochemical study of pituitary ACTH and its hypothalamic secretagogues: CRF, arginine vasopressin (AVP), and oxytocin (OT), both at the level of the synthesizing cell bodies in the hypothalamic paraventricular nucleus and of the releasing fibers in the median eminence (ME). Body weight and daily consumption of food and water were not altered, but social isolation caused a reduction in plasma corticosterone levels, both under basal and stress-stimulated conditions; this was correlated with an increased thymus weight, without affecting adrenal or testicular weights. The immunohistochemical study revealed that isolation caused a smaller increase in the number of ACTH-immunoreactive cells in the pars distalis of the anterior pituitary after exposure to restraint stress, as compared with control animals. This result indicates that fewer corticotrophs were activated by restraint stress in isolated animals, such cells being smaller and exhibiting a smaller ACTH-immunoreactive area than in control animals. Isolated animals also showed an increase in the content of CRF-ir fibers in the ME and a smaller decrease in the neuropeptide immunoreactivity after stress than that observed in control animals. This result could indicate a reduced release of CRF into the portal vasculature in response to acute stress and may partially explain the reduced activation of corticotrophs observed in the pituitary of isolated animals. However, no changes were found in the content of CRF, AVP, or OT within the paraventricular nucleus, nor of the AVP or OT content in the ME. The results of this study show that long-term social isolation after early weaning caused a hypofunction of the HPA axis in the adult rat. This hypofunction was particularly evident after exposure to an acute stressor, suggesting a desensitization of this axis to stressful stimuli.

Animals↗

PubMed1997

Regulated secretion is impaired in AtT-20 endocrine cells stably transfected with botulinum neurotoxin type A light chain.

Botulinum neurotoxin type A (BoNT/A) inhibits neurotransmitter release by specific cleavage of SNAP-25, a synaptosome-associated protein also expressed in the ACTH secretory cell line AtT-20. Expression of light chain BoNT/A (L-BoNT/A) gene transfected into AtT-20 cells resulted in a cleaved form of SNAP-25 indistinguishable from that generated by bona fide BoNT/A. L-BoNT/A-transfected cells showed no difference in replication rate, viability, or phenotype, compared with control AtT-20 cells. In contrast, L-BoNT/A-transfected cells could not be induced to secrete ACTH upon stimulation by 8-bromo-cAMP or KCl. In addition, alpha-latrotoxin induced ACTH release from control cells, but not from L-BoNT/A-transfected cells. These experiments suggest an important role for SNAP-25 in regulated secretion from AtT-20 cells and underline the usefulness of this cell system as a tool for the study of the molecular mechanism of peptide hormone secretion.

8-Bromo Cyclic Adenosine Monophosphate↗

PubMed1997

Immunocytochemical analysis of the synaptic proteins SNAP-25 and Rab3A in human pituitary adenomas. Overexpression of SNAP-25 in the mammmosomatotroph lineages.

SNAP-25 and Rab3A were originally identified as synaptic proteins involved in neuronal membrane traffic. Recently, both proteins have been detected in several mammalian endocrine cell types and have been proposed as essential components of the exocytotic pathway in neuroendocrine cells. In this study, the expression of SNAP-25 and Rab3A was analysed in biopsied human anterior pituitary tumours (21 cases) by immunocytochemical methods. No differences in Rab3A immunoreactivity were observed between tumour and normal pituitary cells. Strong SNAP-25 immunoreactivity was detected in tumour cells of prolactinomas (n = 3). Several growth hormone (GH)/prolactin (PRL) tumours also displayed intense SNAP-25 immunolabelling (n = 3), whereas the remaining GH-secreting adenomas (n = 4) exhibited moderate to weak SNAP-25 immunoreactivity. In contrast, SNAP-25 near-background immunostaining was observed in tumour cells of adrenocorticotrophic hormone (ACTH)-secreting tumours (n = 4) and non-secreting tumours (n = 7), as well as in normal pituitary cells. Since SNAP-25 and Rab3A have been shown to be involved in exocytotic events in rodent endocrine cells, overexpression of SNAP-25 protein in PRL and GH/PRL tumour cells might be implicated in the mechanism of exocytosis of the neoplastic human mammosomatotroph lineages.

Acromegaly↗