Manuel Miguel - Academia.edu (original) (raw)

Papers by Manuel Miguel

Cell and Tissue Research, 2002

In rats, the frequency of spontaneous C-cell tumours is very high and is both age and gender depe... more In rats, the frequency of spontaneous C-cell tumours is very high and is both age and gender dependent. The three specific stages of neoplastic progression can be distinguished into diffuse C-cell hyperplasia, focal C-cell hyperplasia and bona fide C-cell tumours. Based on this hypothetical model of human medullary thyroid carcinoma (MTC), we carried out an immunohistochemical study using different markers (calcitonin, calcitonin gene-related peptide, somatostatin and chromogranin) to verify the existence of any relationship between their expression and the successive steps of tumour development. We found a characteristic immunohistochemical staining pattern, particularly for calcitonin and somatostatin, which distinguishes C-cell tumours from both normal and hyperplastic C cells, with no differences related to the gender of the animals under study. Specifically, a considerable heterogeneity in calcitonin expression was only displayed by C-cell carcinomas, being less pronounced in C-cell adenomas. As for somatostatin, this regulatory peptide was found only in a minority of calcitonin-positive cells in normal and hyperplastic glands. However, in some C-cell adenomas and most Ccell carcinomas nearly all calcitonin-positive cells also coexpressed somatostatin. We conclude that rat C-cell neoplasms constitute a very particular tumour entity which shares many but not all immunohistochemical features with human MTC.

Oxidative Stress and Diseases, 2012

Cell Death & Disease, 2013

Apoptotic microtubule network (AMN) is organized during apoptosis, forming a cortical structure b... more Apoptotic microtubule network (AMN) is organized during apoptosis, forming a cortical structure beneath plasma membrane, which has an important role in preserving cell morphology and plasma membrane permeability. The aim of this study was to examine the role of AMN in maintaining plasma membrane integrity during the execution phase of apoptosis. We demonstrated in camptothecin-induced apoptosis in H460 cells that AMN delimits an active caspase free area beneath plasma membrane that permits the preservation of cellular cortex and transmembrane proteins. AMN depolymerization in apoptotic cells by a short exposure to colchicine allowed active caspases to reach the cellular cortex and cleave many key proteins involved in plasma membrane structural support, cell adhesion and ionic homeostasis. Cleavage of cellular cortex and plasma membrane proteins, such as a-spectrin, paxilin, focal adhesion kinase (FAK), E-cadherin and integrin subunit b4 was associated with cell collapse and cell detachment. Otherwise, cleavage-mediated inactivation of calcium ATPase pump (PMCA-4) and Na þ /Ca 2 þ exchanger (NCX) involved in cell calcium extrusion resulted in calcium overload. Furthermore, cleavage of Na þ /K þ pump subunit b was associated with altered sodium homeostasis. Cleavage of cell cortex and plasma membrane proteins in apoptotic cells after AMN depolymerization increased plasma permeability, ionic imbalance and bioenergetic collapse, leading apoptotic cells to secondary necrosis. The essential role of caspase-mediated cleavage in this process was demonstrated because the concomitant addition of colchicine that induces AMN depolymerization and the pan-caspase inhibitor z-VAD avoided the cleavage of cortical and plasma membrane proteins and prevented apoptotic cells to undergo secondary necrosis. Furthermore, the presence of AMN was also critical for proper phosphatidylserine externalization and apoptotic cell clearance by macrophages. These results indicate that AMN is essential to preserve an active caspase free area in the cellular cortex of apoptotic cells that allows plasma membrane integrity during the execution phase of apoptosis.

New Insights into Fibromyalgia, 2012

Patient's symptoms may derive from poor stressor modulation, sensitization of specific nociceptor... more Patient's symptoms may derive from poor stressor modulation, sensitization of specific nociceptor neurons and pain threshold diminution in response to multiple environmental factors, such as mechanical or emotional trauma, chronic stress or even infections. In recent years, new information to our understanding of FM pathophysiology has emerged. Some genetic polymorphisms and antibodies have been associated with FM, as the serotoninergic system genotype of 5-HTT (

Molecular Syndromology, 2014

For a number of years, coenzyme Q10 (CoQ10) was known for its key role in mitochondrial bioenerge... more For a number of years, coenzyme Q10 (CoQ10) was known for its key role in mitochondrial bioenergetics; later studies demonstrated its presence in other subcellular fractions and in blood plasma, and extensively investigated its antioxidant role. These 2 functions constitute the basis for supporting the clinical use of CoQ10. Also, at the inner mitochondrial membrane level, CoQ10 is recognized as an obligatory cofactor for the function of uncoupling proteins and a modulator of the mitochondrial transition pore. Furthermore, recent data indicate that CoQ10 affects the expression of genes involved in human cell signaling, metabolism and transport, and some of the effects of CoQ10 supplementation may be due to this property. CoQ10 deficiencies are due to autosomal recessive mutations, mitochondrial diseases, aging-related oxidative stress and carcinogenesis processes, and also statin treatment. Many neurodegenerative disorders, diabetes, cancer, and muscular and cardiovascular diseases ...

Toxicology Letters, 2011

Amitriptyline is a tricyclic antidepressant commonly prescribed for the treatment of several neur... more Amitriptyline is a tricyclic antidepressant commonly prescribed for the treatment of several neuropathic and inflammatory illnesses. We have already reported that amitriptyline has cytotoxic effect in human cell cultures, increasing oxidative stress, and decreasing growth rate and mitochondrial activity. Coenzyme Q (CoQ), a component of the respiratory chain and a potent antioxidant, has been proposed as a mitochondrial dysfunction marker. In the present work we evaluated lipid peroxidation, a consequence of oxidative stress, and CoQ level in liver, lung, kidney, brain, heart, skeletal muscle, and serum of mice treated with amitriptyline for two weeks. Lipid peroxidation was increased in a dose-dependent manner in all tissues analyzed. CoQ levels were increased in brain, heart, skeletal muscle, and serum, and strongly decreased in liver and lung. The relation between amitriptyline, CoQ, and oxidative stress is discussed.

Toxicology, 2008

Amitriptyline is a tricyclic antidepressant widely used in the treatment of chronic pain. The obj... more Amitriptyline is a tricyclic antidepressant widely used in the treatment of chronic pain. The objective of the present study was to investigate the potential cytotoxic effects of amitriptyline in human fibroblasts primary culture. Human fibroblast cells were cultured from healthy subjects and incubated with 50 M and 100 M amitriptyline. Cell counting was performed to study dosedependency of toxicity. Lipid peroxidation analysis and western blotting for antioxidants catalase and mitochondrial superoxide dismutase (MnSOD) were carried out in order to evaluate oxidative stress. To investigate mitochondria damage the following determinations were made: cytochrome c, citrate synthase, and mitochondrial membrane potential (Ψ m). Amitriptyline reduced significantly the number of cultured cells, resulting in a decrease of 45.2%, 65.0% and 94.9% when treated with 20 M, 50 M and 100 M amitriptyline, respectively. This drug enhanced the production of oxidized products during lipid peroxidation, inverting the reduced/oxidized ratio to 25% reduction and 75% oxidation after 24 h of amitriptyline administration. A decreased in catalase protein levels has been also observed. Moreover, amitriptyline treatment induced a significant decrease of cytochrome c, Ψ m , and citrate synthase activity; revealing mitochondrial damage. These findings suggest that amitriptyline has a strong cytotoxic effect in human fibroblasts, decreasing growth rate and mitochondrial activity, and increasing oxidative stress.

The FASEB Journal, 2011

Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) is a mitochond... more Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) is a mitochondrial disease most usually caused by point mutations in tRNA genes encoded by mtDNA. Here, we report on how this mutation affects mitochondrial function in primary fibroblast cultures established from 2 patients with MELAS who harbored the A3243G mutation. Both mitochondrial respiratory chain enzyme activities and coenzyme Q 10 (CoQ) levels were significantly decreased in MELAS fibroblasts. A similar decrease in mitochondrial membrane potential was found in intact MELAS fibroblasts. Mitochondrial dysfunction was associated with increased oxidative stress and the activation of mitochondrial permeability transition (MPT), which triggered the degradation of impaired mitochondria. Furthermore, we found defective autophagosome elimination in MELAS fibroblasts. Electron and fluorescence microscopy studies confirmed a massive degradation of mitochondria and accumulation of autophagosomes, suggesting mitophagy activation and deficient autophagic flux. Transmitochondrial cybrids harboring the A3243G mutation also showed CoQ deficiency and increased autophagy activity. All these abnormalities were partially restored by CoQ supplementation. Autophagy in MELAS fibroblasts was also abolished by treatment with antioxidants or cyclosporine, suggesting that both reactive oxygen species and MPT participate in this process. Furthermore, prevention of autophagy in MELAS fibroblasts resulted in apoptotic cell death, suggesting a protective role of autophagy in MELAS fibroblasts.

Rheumatology International, 2013

In order to analyze the association between body mass index (BMI), lipid profile and clinical sym... more In order to analyze the association between body mass index (BMI), lipid profile and clinical symptoms in patients with fibromyalgia, we assessed BMI levels, lipid profile and its association with clinical symptoms in 183 patients with fibromyalgia. The patients were evaluated using tender points, FIQ and Visual Analogue Scales of pain (VAS). Serum lipid profile analysis (total cholesterol, triglyceride, HDL, LDL and VLDL), and biochemical parameters were measured in the biochemistry laboratory. The BMI distribution of the nonobese, overweight and obese patients' groups were relatively even with 37.7, 35.5 and 26.8 %, respectively, with a mean BMI of 27.3 ± 4.9. The number of tender points showed significantly positive correlation with higher BMI (P \ 0.05). A total of 57.9 % of patients showed increased levels of total cholesterol, 63.4 % increased levels of LDL cholesterol and 19.9 % high levels of triglycerides. BMI, total cholesterol and triglycerides showed high association with some clinical parameters. Overweight and lipid profile could be associated with fibromyalgia symptoms. A treatment program with weight loss strategies, and control in diet and increased physical activity is advised to patients.

PLoS ONE, 2011

Background: We examined lipid peroxidation (LPO) in blood mononuclear cells (BMCs) and plasma, as... more Background: We examined lipid peroxidation (LPO) in blood mononuclear cells (BMCs) and plasma, as a marker of oxidative damage, and its association to clinical symptoms in Fibromyalgia (FM) patients. Methods: We conducted a case-control and correlational study comparing 65 patients and 45 healthy controls. Clinical parameters were evaluated using the Fibromyalgia Impact Questionnaire (FIQ), visual analogues scales (VAS), and the Beck Depression Inventory (BDI). Oxidative stress was determined by measuring LPO in BMCs and plasma.

Peptides, 2011

Ghrelin is a 28-amino-acid peptide that stimulates pituitary growth-hormone secretion and modulat... more Ghrelin is a 28-amino-acid peptide that stimulates pituitary growth-hormone secretion and modulates food-intake and energy metabolism in mammals. It is mainly secreted by the stomach, but it is also expressed in many other tissues such as cartilage or the thyroid gland. In the present study we have analyzed by RT-PCR and using immunohistochemistry and immunofluorescence the expression and tissue distribution of ghrelin and its functional receptor (GHS-R type 1α) in thyroid cell-lines and in normal and pathological rat thyroid tissue. Additionally, by measuring the incorporation of BrdU, we have investigated if, as previously noted for FRTL-5 cells, ghrelin enhances the proliferation rate in the PC-Cl3 rat-thyrocyte cell-line. Finally, we have determined the stimulatory effect of ghrelin on TSH-induced expression of the tissue-specific key genes involved in the synthesis of thyroid hormone: thyroglobulin, thyroperoxidase and sodium-iodine symporter. Our data provide direct evidence that C-cell secreted ghrelin may be involved in the paracrine regulation of the thyroid follicular cell function.

Nutrition, 2012

Fibromyalgia (FM) is a chronic pain syndrome with unknown etiology. Recent studies have shown evi... more Fibromyalgia (FM) is a chronic pain syndrome with unknown etiology. Recent studies have shown evidence demonstrating that mitochondrial dysfunction and oxidative stress may have a role in the pathophysiology of FM. Coenzyme Q10 (CoQ10) is an essential electron carrier in the mitochondrial respiratory chain and a strong antioxidant. Low CoQ10 levels have been detected in patients with FM, and a significant decrease of clinical symptoms has been reported after oral CoQ10 supplementation. In this report, we show the effect of CoQ10 treatment on clinical symptoms, blood mononuclear cells, and mitochondrial and oxidative stress markers from a woman with FM. After CoQ10 treatment, the patient reported a significant improvement of clinical symptoms. At the cellular level, CoQ10 treatment restored mitochondrial dysfunction and the mtDNA copy number, decreased oxidative stress, and increased mitochondrial biogenesis. Our results suggest that CoQ10 could be an alternative therapeutic approach for FM.

Journal of Psychiatric Research, 2012

General and Comparative Endocrinology, 2013

Besides intervening in calcium homeostasis by means of calcitonin, C cells are also implicated in... more Besides intervening in calcium homeostasis by means of calcitonin, C cells are also implicated in the synthesis of an increasing number of regulatory peptides that could exert a paracrine regulation on the neighbouring follicular cells. Among the latest peptides reported in C cells, there are several characteristic hypothalamic peptides, such as TRH, CART, and ghrelin, which are mainly involved in the regulation of the metabolism at hypothalamic-pituitary-thyroid axis. The main aim of the present work has been to study the synthesis of the referred hypothalamic peptides by normal and neoplastic C cells of different mammals as well as in C-cell lines of both rat (CA-77, 6-23) and human (TT) origins in order to elucidate whether this is a fact in this kind of vertebrates. With that objective, we have applied the immunoperoxidase technique to analyze the presence of TRH, CART, ghrelin, and somatostatin in thyroid tissues of different species, and immunofluorescence to study those same peptides in C-cell cultures. Furthermore, we have investigated their expression at mRNA level by RT-PCR analysis. Our results demonstrate immunocolocalization of CART, ghrelin, somatostatin and TRH with calcitonin in normal C cells of different mammals, as well as in rat and human neoplastic C cells. We also confirm the expression of those peptides in rat and human C-cell lines by RT-PCR. Consequently, we can conclude that the synthesis of those peptides by C cells is a general event characteristic of the thyroid gland in mammals.

Clinical Biochemistry, 2010

Coenzyme Q(10) (CoQ(10)) is an essential electron carrier in the mitochondrial respiratory chain ... more Coenzyme Q(10) (CoQ(10)) is an essential electron carrier in the mitochondrial respiratory chain and a strong antioxidant. Signs associated with skin alteration and mitochondrial dysfunction have been observed in patients with fibromyalgia (FM). The aim of this study was to analyze CoQ(10) levels, mitochondrial dysfunction, and oxidative stress in plasma, blood mononuclear cells, and skin biopsies from FM patients. We studied CoQ(10) level by HPLC in plasma, blood mononuclear cells, and skin obtained from patients with FM and healthy control subjects. Oxidative stress markers and mitochondrial respiratory chain enzyme activities were analysed in both plasma, blood mononuclear cells, and skin biopsies from FM patients. Oxidative stress, mitochondrial dysfunction, and CoQ(10) deficiency have been observed in blood mononuclear cells and skin biopsies. In our patients, mitochondrial dysfunction and CoQ(10) deficiency are present in several tissues. These results may contribute to the understanding of the pathophysiology of FM, and, moreover, CoQ(10) deficiency could represent a good marker for the diagnosis of FM.

Clinical Biochemistry, 2009

Coenzyme Q10 (CoQ(10)) is an essential electron carrier in the mitochondrial respiratory chain an... more Coenzyme Q10 (CoQ(10)) is an essential electron carrier in the mitochondrial respiratory chain and a strong antioxidant. Signs and symptoms associated with muscular alteration and mitochondrial dysfunction, including oxidative stress, have been observed in patients with fibromyalgia (FM). The aim was to study CoQ(10) levels in plasma and mononuclear cells, and oxidative stress in FM patients. We studied CoQ(10) level by HPLC in plasma and peripheral mononuclear cells obtained from patients with FM and healthy control subjects. Oxidative stress markers were analyzed in both plasma and mononuclear cells from FM patients. Higher level of oxidative stress markers in plasma was observed respect to control subjects. CoQ(10) level in plasma samples from FM patients was doubled compared to healthy controls and in blood mononuclear cells isolated from 37 FM patients was found to be about 40% lower. Higher levels of ROS production was observed in mononuclear cells from FM patients compared to control, and a significant decrease was induced by the presence of CoQ(10). The distribution of CoQ(10) in blood components was altered in FM patients. Also, our results confirm the oxidative stress background of this disease probably due to a defect on the distribution and metabolism of CoQ(10) in cells and tissues. The protection caused in mononuclear cells by CoQ(10) would indicate the benefit of its supplementation in FM patients.

British Journal of Pharmacology, 2012

BACKGROUND AND PURPOSE MELAS (mitochondrial encephalomyopathy, lactic acidosis and stroke-like ep... more BACKGROUND AND PURPOSE MELAS (mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes) is a mitochondrial disease most usually caused by point mutations in tRNA genes encoded by mitochondrial DNA (mtDNA). Approximately 80% of cases of MELAS syndrome are associated with a m.3243A > G mutation in the MT-TL1 gene, which encodes the mitochondrial tRNALeu (UUR). Currently, no effective treatments are available for this chronic progressive disorder. Treatment strategies in MELAS and other mitochondrial diseases consist of several drugs that diminish the deleterious effects of the abnormal respiratory chain function, reduce the presence of toxic agents or correct deficiencies in essential cofactors. EXPERIMENTAL APPROACH We evaluated the effectiveness of some common pharmacological agents that have been utilized in the treatment of MELAS, in yeast, fibroblast and cybrid models of the disease. The yeast model harbouring the A14G mutation in the mitochondrial tRNALeu(UUR) gene, which is equivalent to the A3243G mutation in humans, was used in the initial screening. Next, the most effective drugs that were able to rescue the respiratory deficiency in MELAS yeast mutants were tested in fibroblasts and cybrid models of MELAS disease. KEY RESULTS According to our results, supplementation with riboflavin or coenzyme Q10 effectively reversed the respiratory defect in MELAS yeast and improved the pathologic alterations in MELAS fibroblast and cybrid cell models. CONCLUSIONS AND IMPLICATIONS Our results indicate that cell models have great potential for screening and validating the effects of novel drug candidates for MELAS treatment and presumably also for other diseases with mitochondrial impairment.