Biomedical subjects

Luis F Callado

Publications and source records attributed to Luis F Callado.

16 recordsLinked to original sources

PubMed2025

Global lncRNA expression profiles in medulloblastoma reveal crucial lncRNA-oncogene interactions in Sonic hedgehog and Group 4.

BACKGROUND: Advances in multi-omic studies have improved medulloblastoma (MB) characterization, yet novel molecular biomarkers are needed to refine tumor biology and therapeutic strategies. Current profiling mainly targets the protein-coding genome, while the potential of noncoding regions remains unexplored. This study aims to identify long noncoding RNAs (lncRNAs), emerging as crucial regulators in MB, as potential key biomarkers specific to molecular group, enhancing understanding of MB's genomic landscape. METHODS: RNA-seq data from 54 Spanish MB patients (C1) and 207 public samples (C2) were analyzed to profile lncRNAs. Expression and Weighted Gene Coexpression Network (WGCNA) analyses were performed to identify lncRNA-oncogene interactions. Group-specific interactions were examined to infer their role in MB pathogenesis and highlight potential lncRNA involvement in disease mechanisms. RESULTS: LncRNA expression profiles identified 4 clusters corresponding to the MB molecular groups, confirming their potential as biomarkers. Expression and WGCNA analyses revealed group-specific lncRNAs for Sonic hedgehog (SHH), Group 3 (Gr3), and Group 4 (Gr4) MB. Lnc-SMARCA2 was exclusively upregulated in SHH MB, and associated with ATOH1 and PDLIM3, key cilium regulators of this group's cell of origin. In Gr4 MB, MGC32805 and LOC107986446 were upregulated and linked to SNCAIP, potentially influencing PRDM6 activation via enhancer hijacking. Additionally, a 5-lncRNA signature linked to phototransduction was exclusive to Gr3, offering insights into its lineage switch and molecular regulation. CONCLUSIONS: Lnc-SMARCA2 and, MGC32805 and LOC107986446, are exclusively deregulated in SHH and Gr4 MB, respectively, and directly associated with group-specific MB oncogenes, representing promising novel biomarkers and therapeutic targets in MB.

cancer biomarkers↗

PubMed2006

Synthesis and pharmacological studies of new hybrid derivatives of fentanyl active at the mu-opioid receptor and I2-imidazoline binding sites.

Two series of fentanyl-derived hybrid molecules bearing potent I2-imidazoline binding site (IBS) ligands (i.e., guanidine and BU224 moieties) linked with an aliphatic (m=2, 3, 4, 6, 7, 8, 9 and 12 methylene units) or aromatic spacer were prepared. Their affinities for the mu-opioid receptors and for the I2-IBS were determined through competition binding studies on human postmortem brain membranes. Whereas the BU224 hybrid molecules bound to the mu-opioid receptor and the I2-IBS in the micromolar to low micromolar range, the alkaneguanidine series exhibited remarkable affinities in the nanomolar range for both receptors. [35S]GTPgammaS functional assays were performed on human postmortem brain membranes with selected ligands from each series (4f and 8g) showing the highest dual affinity for the mu-opioid receptor and I2-IBS affinities. Both compounds displayed agonist properties: at the mu-opioid receptor for the alkaneguanidine derivative 4f (spacer: six methylene units) and at a G-protein coupled receptor (GPCR) which remains to be determined for 8g. The lack of analgesic properties of 4f in vivo (i.e., hot plate and writhing tests in mice), discordant with the good in vitro binding data (Ki mu=1.04+/-0.28 nM, Ki I2=409+/-238 nM), may possibly be due to the low intrinsic efficacy of the compound. Alternatively, a low access to the central nervous system for this kind of hybrid molecules cannot be ruled out. Two new compounds reported here (9f and 13), which were not dual acting, are worth mentioning for their outstanding binding affinities; 9f bound to the mu-opioid receptor with a picomolar affinity (Ki=0.0098+/-0.0033 nM), whereas 13 presented an I2-IBS affinity (Ki=18+/-11 nM) similar to the reference compound BU224.

Analgesics, Opioid↗

PubMed2006

Levels of G-protein alpha q/11 subunits and of phospholipase C-beta(1-4), -gamma, and -delta1 isoforms in postmortem human brain caudate and cortical membranes: potential functional implications.

The levels of expression of G-protein alpha(q/11) (Galpha(q/11)) subunits and PLC-beta(1-4), -gamma, and -delta(1) isoforms were quantified by Western blot analysis in order to establish their contribution to the patterns of PLC functioning reported here. Quantitative measurements of the levels of Galpha(q/11) subunits in each region were obtained by comparison with known amounts of Escherichia coli expressed recombinant Galpha(q) subunits. Quantitative analysis indicated that Galpha(q/11) subunits are abundant polypeptides in human brain, with values ranging from about 1200 ng/mg in cerebral cortex to close to 900 ng/mg of membrane protein in caudate. In cerebral cortical membranes, the PLC-beta(1) isoform was more abundant than in caudate membranes. The highest levels of PLC-beta(2) expression were detected in caudate membranes. PLC-beta(3) was little expressed, and there were no significant differences in the relative values between both brain regions. Finally, the levels of the PLC-beta(4) isoform were significantly lower in caudate than in cortical membranes. It is concluded that although most of these data represent relative, not absolute, measures of protein levels within these regions, they contribute nonetheless to the significant differences observed in signaling capacities through the PLC system in both human brain regions.

Adult↗

PubMed2005

The N251K functional polymorphism in the alpha(2A)-adrenoceptor gene is not associated with depression: a study in suicide completers.

RATIONALE: alpha(2A)-Adrenoceptor up-regulation and supersensitivity have been described in the postmortem brains of depressed suicide victims and in the platelets of depressed subjects. The C to G transversion at nucleotide 753 (Asn to Lys change at amino acid 251 or N251K) is a low-frequency polymorphism of the alpha(2A)-adrenoceptor gene that results in a gain-of-function phenotype. A previous study has suggested an association between completed suicide and this polymorphism. OBJECTIVES: The single functional polymorphism N251K was tested in a large sample (n=214) of completed suicides, controlling for the antemortem psychiatric diagnosis, and matched controls (n=176). METHODS: Postmortem brain DNA was extracted and the alpha(2A)-adrenoceptor gene fragment was amplified by polymerase chain reaction, followed by a StyI restriction endonuclease digestion. Amplified products were sequenced to confirm the presence of the alpha(2A)-adrenoceptor gene fragment where the polymorphism is located. RESULTS: The N251K polymorphism was absent in both suicide victim and control groups. No association between the polymorphism and suicide or depression was established. CONCLUSIONS: The N251K polymorphism does not represent a genetic factor to explain the alpha(2A)-adrenoceptor hyperactivity in the brains of depressed suicide victims. Association between suicide and this polymorphism was not replicated.

Brain↗

PubMed2005

Opposite changes in imidazoline I2 receptors and alpha2-adrenoceptors density in rat frontal cortex after induced gliosis.

Opposite age-dependent changes in alpha2-adrenoceptor and imidazoline I2 receptor (I2-IRs) density have been related to brain gliosis development with aging. To check this hypothesis we applied in rats a model of reactive gliosis induced by heat. The specific binding of [3H]idazoxan (0.5-20 nM) in the presence of (-)adrenaline (5 x 10(-6) M) to membranes from rat brain cortex showed that the density of I(2)-IRs was significantly higher in membranes of injured cortex (Bmax=60+/-6 fmol/mg protein; n=9) than in control (Bmax=38+/-3 fmol/mg protein; n=9; p=0.0053). Conversely, the density of alpha2-adrenoceptors, measured by [3H]clonidine (0.25-16 nM), in the injured cortex (Bmax=75+/-4 fmol/mg protein; n=9) was significantly lower than in sham membranes (Bmax=103+/-7 fmol/mg protein; n=9; p=0.0035). No significant differences in receptor's affinity were observed between both groups. These results support the hypothesis that gliosis induces opposite changes in alpha2-adrenoceptor and I2-IR density.

Actins↗

PubMed2004

Fentanyl derivatives bearing aliphatic alkaneguanidinium moieties: a new series of hybrid molecules with significant binding affinity for mu-opioid receptors and I2-imidazoline binding sites.

A new series of fentanyl derivatives [i.e., N-[1-(2-phenethyl)-4-piperidyl]-N-(guanidinoalkyl)propanamide] bearing aliphatic alkaneguanidinium moieties were prepared. Their affinities for the micro opioid receptors and for the I(2)-imidazoline binding sites (I(2)-IBS) were determined on human post-mortem prefrontal cortex membranes. All of these hybrid compounds had significant and/or very high affinity for both receptors in the nanomolar range, meaning an improvement compared to the prototype N-[1-(2-phenethyl)-4-piperidyl]-N-(guanidinopropyl)propanamide previously reported.

Alkanes↗

PubMed2004

Effectiveness of pindolol plus serotonin uptake inhibitors in depression: a meta-analysis of early and late outcomes from randomised controlled trials.

BACKGROUND: Contradictory results on the efficacy of pindolol associated with selective serotonin reuptake inhibitors (SSRIs) in depressive illness have been published and no former review has produced an overall figure of its efficacy. This study aims to review the efficacy and tolerability of pindolol plus SSRIs in depressive illness. METHODS: A meta-analysis of randomised controlled trials (RCTs) comparing pindolol plus SSRIs with placebo plus SSRIs. RESULTS: Nine RCTs met inclusion criteria. Outcome favoured pindolol at 2 weeks time (N=5; OR=2.8; 95% CI 1.4-5.7), but not at four to 6 weeks (N=7; OR=1.4; 95% CI 0.8-2.7). Results for early outcome studies were robust to sensitivity analysis. Nineteen more studies, averaging null results, would be needed to change the overall probability (P=0.0001) to a non-significant figure. CONCLUSIONS: Pindolol seems to hasten the response to SSRIs in depression with a timing window circumscribed to the first weeks of treatment.

Adolescent↗

PubMed2004

Stereoselective effects of ketamine on dopamine, serotonin and noradrenaline release and uptake in rat brain slices.

Ketamine (2-(2-chlorophenyl)-(1-methylamino)-cyclohexanone) is a rapid-acting dissociative general anaesthetic whose hallucinogenic properties have made it a popular drug of abuse. Ketamine comprises two optical isomers, with differing pharmacology. In the present study, the effects of (+)- and (-)-ketamine on stimulated efflux and reuptake of dopamine (DA), noradrenaline (NA) and serotonin (5-HT) were compared in isolated superfused slices of the rat caudatoputamen (CPu), ventral bed nucleus of the stria terminalis (BSTV) or dorsal raphe nucleus (DRN), respectively. Monoamine efflux was elicited by local electrical stimulation (20 pulses, 100 Hz trains) at tungsten microelectrodes and measured at adjacent carbon fibre microelectrodes using fast cyclic voltammetry (FCV). In CPu (+)-ketamine increased stimulated DA efflux and slowed DA reuptake in a concentration-dependent manner (25-200 microM). At 100 microM (+)-ketamine increased DA efflux by 109+/-20% (mean+/-S.E.M., n=13) of control values after 30 min (P<0.001 versus control) and prolonged uptake half-time (t(1/2)) by 76+/-38% (n=9, P<0.001) of control. In contrast (-)-ketamine (100 microM) had no effect on DA efflux or uptake. In DRN, both isomers (100 microM) increased stimulated 5-HT efflux. (-)-Ketamine had a larger effect (P<0.001), an 88+/-15% increase in 5-HT efflux (n=9) versus 46+/-10% (n=8) for the (+)-isomer. The isomers had similar effects on 5-HT uptake, increasing t(1/2) by approximately 200%. No evidence of stereospecificity was seen in BSTV: both isomers had small effects (+)- and (-)-ketamine (100 microM) increasing NA efflux by 43+/-10% (n=7, P<0.001) and 29+/-8% (n=7, P<0.001), respectively. The isomers also had identical effects on NA uptake, each increasing uptake t(1/2) by approximately 100%. In summary, our data show that the optical isomers of ketamine have strikingly different stereospecificity for the monoamine systems and one might predict, therefore, a different psychotomimetic potential.

Animals↗

PubMed2004

Differential postmortem delay effect on agonist-mediated phospholipase Cbeta activity in human cortical crude and synaptosomal brain membranes.

The phosphoinositide signal transduction system, and particularly, phospholipase Cbeta isozymes, are relevant in the etiopathogeny of human neuropsychiatric pathologies such as depression. Stimulation of phospholipase Cbeta activity by muscarinic receptors and G proteins was determined in crude and synaptosomal membrane preparations from nine postmortem human frontal cortices (postmortem delay range 8 to 50 h). Thus, the phospholipase Cbeta activity was determined by measuring the hydrolysis of exogenous [3H]-phosphatidylinositol 4,5-bisphosphate. There was a postmortem delay-mediated decrease in the PIP2 hydrolysis irrespective of the membrane preparation used (P < 0.05). Moreover, there were statistically significant differences for exponential decay curve parameters (K factor and Span) of PLCbeta activity induced by agonist-mediated activation between crude and synaptosomal membrane preparations. These results show that the postsynaptic component of the PLCbeta activity is more sensible to the postmortem delay effect.

Adult↗

PubMed2002

Synthesis and opioid activity of new fentanyl analogs.

Three new fentanyl analogs (compounds 3-4-5) have been synthesized and evaluated for antinociceptive properties using the writhing test. The analgesic property of the active compound, N-[1-phenylpyrazol-3-yl]-N-[1-(2-phenethyl)-4-piperidyl)] propenamide (compound 4), was tested using the hot plate test in mice. Its opioid agonistic activity was characterized using three isolated tissues: guinea pig ileum, mouse vas deferens, and rabbit vas deferens. Compound 4 was as effective as fentanyl or morphine and it showed less antinociceptive potency than fentanyl but it was more potent than morphine. The duration of the antinociception was similar to that of fentanyl. This compound inhibited the electrically evoked contractions of myenteric plexus-longitudinal muscle strips of guinea pig ileum and of mouse vas deferens but not those of rabbit vas deferens. These effects could be reversed by micro selective antagonists (naloxone and/or CTOP) but not by the delta selective antagonist naltrindole, thus indicating that the compound acted as a micro opioid agonist. Finally, the binding data confirmed that compound 4 had high affinity and selectivity for the micro-receptor.

Analgesics, Opioid↗

PubMed2002

Long-acting fentanyl analogues: synthesis and pharmacology of N-(1-phenylpyrazolyl)-N-(1-phenylalkyl-4-piperidyl)propanamides.

The synthesis of new fentanyl analogues in which the benzene ring of the propioanilido group has been replaced by phenylpyrazole is described. Antinociceptive activity was evaluated using the writhing and hot plate tests in mice. Two compounds, and, showed interesting analgesic properties, being more potent than morphine and less than fentanyl but with longer duration of action. These compounds inhibited the electrically evoked muscle contraction of guinea pig ileum and mouse vas deferens but not that of rabbit vas deferens and the effects could be reversed by antagonists (naloxone and/or CTOP), thus indicating that the compounds acted as mu agonists. Finally, the binding data confirmed that the compounds had high affinity and selectivity for the mu receptor.

Amides↗

PubMed2002

Guanidinium and aminoimidazolinium derivatives of N-(4-piperidyl)propanamides as potential ligands for mu opioid and I2-imidazoline receptors: synthesis and pharmacological screening.

Derivatives of N-(1-phenethyl-4-piperidyl)propanamides incorporating guanidinium and 2-aminoimidazolinium groups have been prepared by a synthetic approach involving first introduction of a spacer between the piperidine and the functional group by reductive amination of piperidinone. The formation of each of these functional groups was carried out using N-N'-di(tert-butoxycarbonyl)thiourea and 2-methylthioimidazolinium iodide, respectively. These structures have been designed to incorporate two pharmacologic goals into one entity. Radioligand binding assays have been used to study their affinity for opioid (mu, delta and kappa) and I2-imidazoline receptors. Two of them, 10 and 16, showed high affinity for mu opioid receptors and functionally they had moderate analgesic properties in the hot plate and writhing tests. The in vitro studies on guinea pig ileum (GPI) indicated that both compounds are mu opioid agonists. In what concerns I2-imidazoline receptor activity, these derivatives showed low affinity around 6 to 7 times less than idazoxan.

Amides↗

PubMed2002

I(2)-imidazoline binding site affinity of a structurally different type of ligands.

Two families of compounds with affinity towards the I(2) imidazoline binding sites are reported. The first is a family of compounds structurally related to agmatine with two guanidine or 2-aminoimidazoline groups at each end of an aliphatic chain of six, eight, nine or 12 methylene groups. Second, and following the model of clonidine, we propose another family of compounds also with two guanidine or 2-aminoimidazoline groups at each end of a chain consisting of two phenyl rings connected by groups such as CH(2), CO, NH and SO(2). The affinity of the compounds towards the I(2) imidazoline binding sites was then evaluated in human brain tissues. In order to determine their pharmacological selectivity versus alpha(2)-adrenoceptors, the affinity for these receptors was also evaluated for the compounds with the highest affinities at I(2) imidazoline binding sites. The results obtained show that many of the compounds exhibit a considerable affinity towards the I(2) imidazoline binding sites. The aliphatic derivatives, in particular, present a very interesting selectivity for the I(2) imidazoline binding sites versus the alpha(2) adrenoceptors. To better understand these findings, mono-guanidinium analogues of the aliphatic derivatives were synthesised and tested showing poor affinity for I(2) imidazoline binding sites. The importance of these results lies in the novelty of the chemical structures studied (dicationic aliphatic compounds particularly) because they are significantly different to those of the I(2) imidazoline binding site ligands reported to date.

Binding Sites↗

PubMed2002

Altered presynaptic function in monoaminergic neurons of monoamine oxidase-A knockout mice.

Monoamine oxidase-A knockout (MAO-A KO) mice have elevated brain serotonin (5-HT) and noradrenaline (NA) levels, and one would therefore anticipate increased monoamine release and compensatory changes in other aspects of presynaptic monoamine function. In this study we used voltammetry in brain slices from the locus coeruleus (LC), dorsal raphe (DRN) and striatum (CPu) in 7-week-old MAO-A KO and C3H control mice to measure stimulated monoamine efflux and its control by amine transporters and autoreceptors. In LC, peak NA efflux on stimulation (99 pulses, 100 Hz) was higher in MAO-A KO than C3H mice (938 +/- 58 nm cf. 511 +/- 42 nm; P < 0.001). The NA uptake half time (t(1/2)) was longer in MAO-A KO than in C3H mice (6.0 +/- 0.9 s cf. 1.9 +/- 0.3 s; P < 0.001) and the selective NA reuptake inhibitor desipramine (50 nm) had a smaller effect in MAO-A KO mice. NA transporter binding was significantly lower in the LC of MAO-A KO mice compared to C3H controls (P < 0.01) but not in the DRN. The alpha 2 agonist dexmedetomidine (10 nm) decreased stimulated NA efflux more in C3H than in MAO-A KO mice (73.3% cf. 29.6% inhibition, P < 0.001). In DRN, peak 5-HT efflux on stimulation (99 pulses, 100 Hz) was greater (P < 0.01) in MAO-A KO (262 +/- 44 nm) than C3H mice (157 +/- 16 nm). Moreover, 5-HT uptake t(1/2) was longer (P < 0.05) in MAO-A KO than in C3H mice (8.8 +/- 1.1 s cf. 4.9 +/- 0.6 s, P < 0.05) and the effect of citalopram (75 nm) was attenuated in MAO-A KOs. Serotonin transporter binding was also lower in both the DRN and LC of MAO-A KO mice. The 5-HT(1A) agonist 8-OH-DPAT (1 microm) decreased 5-HT efflux more in C3H than in MAO-A KO mice (38.3% inhibition cf. 21.6%, P < 0.001). In contrast, there were no significant differences between MAO-A KO and C3H mice in CPu dopamine efflux and uptake and the effect of the D(2/3) agonist quinpirole was similar in the two strains. In summary, MAO-A KO mice show major dysregulation of monoaminergic presynaptic mechanisms such as autoreceptor control and transporter kinetics.

Adrenergic Uptake Inhibitors↗

PubMed2002

Interactions of platelets with Synthocytes, a novel platelet substitute.

A platelet substitute, Synthocytes, is being developed for the prevention and treatment of thrombocytopenia. Synthocytes are composed of fibrinogen adsorbed on heat stabilised albumin microcapsules of defined size. The purpose of this study was to perform experiments in vitro to investigate the capacity of Synthocytes to interact with platelets, one of the means through which Synthocytes may contribute to haemostatic plug formation in vivo. Synthocytes were found to interact with platelets as shown by platelet aggregation assays and measurements of [(14)C]5HT release from platelets in whole blood and platelet-rich plasma. Platelet-Synthocytes co-aggregate formation was demonstrated directly using flow cytometry and the presence of activated platelets in these co-aggregates was demonstrated using an antibody to P-selectin. Synthocytes enhanced platelet responsiveness to conventional aggregating agents such as ADP. Indeed, antagonists of the action of ADP on platelets inhibited the direct effects of Synthocytes on platelets in whole blood, as did a GPIIb/IIIa antagonist. Enhancement of annexin V binding was also observed, indicative of increased pro-coagulant activity. Experiments performed with control microcapsules (lacking fibrinogen) confirmed the importance of fibrinogen in the interactions that occurred. The results suggest that fibrinogen on the surface of Synthocytes can interact with GPIIb/IIIa on platelets to induce platelet activation, secretory activity and aggregation, and that ADP contributes to this process. This initial interaction renders platelets more susceptible to the stimulatory effects of other platelet-activating agents. It is considered likely that in the clinical setting of thrombocytopenia any interaction between Synthocytes and residual platelets that are present may contribute to primary haemostasis.

Adenosine Diphosphate↗

PubMed2002

Assessment of the quality of medical documents issued in central police stations in Madrid, Spain: the doctor's role in the prevention of ill-treatment.

Doctors sometimes assess allegations of ill-treatment. Reports from such examinations may be used if the practice of the police is to be appraised: they should therefore be relevant and exhaustive. We assessed, retrospectively, the quality of 318 medical documents concerning 100 persons held in central police stations in Madrid, Spain, from 1991 to 1994. In 71 documents concerning 44 persons the doctors quoted the detainee as alleging ill-treatment. Most of the documents appeared to lack significant information on history of ill-treatment and description of the clinical examination. Of 34 conclusions, ten were unacceptable and the premises were insufficient in 16. These observations point to weaknesses and needs for improvements in the fulfillment of the role of doctors as safeguards of the rights of detainees. Medical examinations should be conducted outside the control of police officers, by a neutral doctor using a check-list/protocol. The quality of the report should fulfill international standards.

Adult↗