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M Giralt

Publications and source records attributed to M Giralt.

At least 19 recordsLinked to original sources
PubMed2000

Co-morbidity in Gaucher's disease results of a nationwide enquiry in Spain.

SHORT INTRODUCTION: Gaucher's disease (GD) is an autosomal recessive disease produced by mutations of the Glucocerebrosidase gene. Carriers are considered to be healthy subjects because there is no manifestation of the disease, but they show signs of macrophage disfunction. The aim of the study was to determine if GD patients and non affected carriers risk suffering other diseases when compared to healthy non-carrier relatives. MATERIAL AND METHODS DESIGN: Epidemiologic study of historic cohorts. The fact that they have one or two mutated alleles has been considered to be the risk factor leading to other conditions (Dementia, Parkinson disease, Ischemic stroke, Ischemic heart disease, Non rheumatic valvular disease, Cancer hematological and non-hematological, Pulmonary fibrosis, Tuberculosis, Gallstones and Schizophrenia). All people, patients, carriers and healthy controls shared the same genetical background and environmental influence. - Patients and relatives enrolled on the Spanish Gaucher Disease Registry were evaluated. STATISTICS: For the Relative-Risk calculation the Mantel-Haenszel test was applied. Yates' correction was used when size sample was too small. A value of p <0.05 was accepted for statistical significance. RESULTS: 370 people, from 79 different families, were surveyed. We received evaluable information from 45 families (56%), totalling 258 people (69%): 59 healthy subjects (Mean age 32. 20, RANGE: 10-85; M 57.63%/F 42.37%), 132 carriers (Mean age 35.91, RANGE: 1-79; M 56.82%/F 43.18%) and 67 patients (Mean age 32.16, Range: 1-76; M 44.78%/F 55.22%. - Relative Risk of suffering any disease with regard to Gaucher's status: Patient vs Healthy 9.69 (95% Confidence interval [CI] 2.00-63.99; p 0.0006). Patient vs Carrier 3.74 (CI 1.53-9.27; p 0.001); Carrier vs Healthy 2.59 (CI 0. 52-12.50; p 0.21). Relative Risk of suffering any disease with regard to sex was 3.96 for female patients (CI 1.01-16.75; p 0.02) and 1.34 for female carriers (CI 0.27-6.75; p = 0.68). CONCLUSION: As a group, Gaucher's patients seem to have a greater risk of suffering other common unrelated diseases than carriers or healthy relatives. This excess of risk is particularly higher among female patients and can not be explained in terms of differences in age. Carrier status doesn't seem to highten the risk of suffering other diseases.

Adolescent↗
PubMed2000

Both retinoic-acid-receptor- and retinoid-X-receptor-dependent signalling pathways mediate the induction of the brown-adipose-tissue-uncoupling-protein-1 gene by retinoids.

The intracellular pathways and receptors mediating the effects of retinoic acid (RA) on the brown-fat-uncoupling-protein-1 gene (ucp-1) have been analysed. RA activates transcription of ucp-1 and the RA receptor (RAR) is known to be involved in this effect. However, co-transfection of an expression vector for retinoid-X receptor (RXR) increases the action of 9-cis RA but not the effects of all-trans RA on the ucp-1 promoter in brown adipocytes. Either RAR-specific ¿p-[(E)-2-(5,6,7,8,-tetrahydro-5,5,8, 8-tetramethyl-2-naphthalenyl)-1-propenyl]benzoic acid¿ or RXR-specific [isopropyl-(E,E)-(R,S)-11-methoxy-3,7, 11-trimethyldodeca-2,4-dienoate, or methoprene] synthetic compounds increase the expression of UCP-1 mRNA and the activity of chloramphenicol acetyltransferase expression vectors driven by the ucp-1 promoter. The RXR-mediated action of 9-cis RA requires the upstream enhancer region at -2469/-2318 in ucp-1. During brown-adipocyte differentiation RXRalpha and RXRgamma mRNA expression is induced in parallel with UCP-1 mRNA, whereas the mRNA for the three RAR subtypes, alpha, beta and gamma, decreases. Co-transfection of murine expression vectors for the different RAR and RXR subtypes indicates that RARalpha and RARbeta as well as RXRalpha are the major retinoid-receptor subtypes capable of mediating the responsiveness of ucp-1 to retinoids. It is concluded that the effects of retinoids on ucp-1 transcription involve both RAR- and RXR-dependent signalling pathways. The responsiveness of brown adipose tissue to retinoids in vivo relies on a complex combination of the capacity of RAR and RXR subtypes to mediate ucp-1 induction and their distinct expression in the differentiated brown adipocyte.

Adipose Tissue, Brown↗
PubMed2000

Metallothionein induction by restraint stress: role of glucocorticoids and IL-6.

Restraint stress increased liver metallothionein-I (MT-I) mRNA and MT-I+II protein levels. The glucocorticoid receptor antagonist RU 486 decreased this response. In contrast, adrenalectomy only decreased MT-I+II protein levels. Moreover, corticosterone or progesterone did not reverse the effect of RU 486. These results suggest that glucocorticoids are important for MT-I+II protein synthesis but not for MT-I mRNA accumulation during restraint stress, and that other factors must be involved in this process. Interleukin-6 (IL-6) deficient mice showed a significant decrease of restraint stress-induced liver MT-I mRNA levels (approximately 30% of IL-6+/+ mice) up to approximately 4-5 hours after the onset of stress. Western blotting of hepatic nuclear proteins showed that the IL-6 responsive transcription factor Stat3, which has been shown to mediate MT induction by inflammation, was also activated by restraint stress. Results after extended periods of restraint stress indicate that IL-6 participates early and transiently in the process. The analysis of the expression of the acute phase plasma protein serum amyloid A suggests that restraint stress elicits an acute phase response similar to that caused by inflammation.

Adrenalectomy↗
PubMed2000

Metallothioneins are upregulated in symptomatic mice with astrocyte-targeted expression of tumor necrosis factor-alpha.

Transgenic mice expressing TNF-alpha under the regulatory control of the GFAP gene promoter (GFAP-TNFalpha mice) exhibit a unique, late-onset chronic-progressive neurological disorder with meningoencephalomyelitis, neurodegeneration, and demyelination with paralysis. Here we show that the metallothionein-I + II (MT-I + II) isoforms were dramatically upregulated in the brain of symptomatic but not presymptomatic GFAP-TNFalpha mice despite TNF-alpha expression being present in both cases. In situ hybridization analysis for MT-I RNA and radioimmunoassay results for MT-I + II protein revealed that the induction was observed in the cerebellum but not in other brain areas. Increased MT-I RNA levels occurred in the Purkinje and granular neuronal layers of the cerebellum but also in the molecular layer. Reactive astrocytes, activated rod-like microglia, and macrophages, but not the infiltrating lymphocytes, were identified as the cellular sources of the MT-I + II proteins. In situ hybridization for MT-III RNA revealed a modest increase in the white matter of the cerebellum, which was confirmed by immunocytochemistry. MT-III immunoreactivity was present in cells which were mainly round or amoeboid monocytes/macrophages. The pattern of expression of the different MT isoforms in the GFAP-TNFalpha mice differed substantially from that described previously in GFAP-IL6 mice, demonstrating unique effects associated with the expression of each cytokine. The results suggest that the MT expression in the CNS reflects the inflammatory response and associated damage rather than a direct role of the TNF-alpha in their regulation and support a major role of these proteins during CNS injury.

Animals↗
PubMed2000

Effect of dietary zinc deficiency on brain metallothionein-I and -III mRNA levels during stress and inflammation.

Zinc is an essential heavy metal for the normal function of the central nervous system (CNS), but the knowledge of its metabolism and functions is scarce. In this report we have studied the effect of a zinc deficient diet on the regulation of brain metallothioneins (MTs). In situ hybridization analysis revealed that brain MT-I induction by restraint stress was significantly blunted in some but not all brain areas in the mice fed the zinc deficient diet compared to normally fed mice. In contrast, brain MT-I induction by the administration of bacterial lipopolysaccharide (LPS) was not significantly lower in the mice fed the zinc deficient diet. In contrast to MT-I, MT-III mRNA levels were minimally affected by either stress or LPS. Yet, significant decreasing effects of the zinc deficient diet were observed in areas such as the neocortex, CA1-CA3 neuronal layer and dentate gyrus of the hippocampus, and the Purkinje neuronal layer of the cerebellum. These results demonstrate that dietary zinc deficiency impairs the response of brain MTs during both stress and LPS-elicited inflammatory response in a highly specific manner.

Animals↗
PubMed2000

Inhibition by CCK of ascending contraction elicited by mucosal stimulation in the duodenum of the rat.

CCK released by intraluminal stimuli modifies duodenal activity contributing to a decrease in gastric emptying. However, the neural mechanisms by which CCK controls motility are not well known. The aim of this study was to investigate the interaction between CCK and the enteric nervous system through the study of the effects of CCK-8 on ascending excitation. Anaesthetized Sprague-Dawley rats were prepared with a strain-gauge sutured to the duodenum wall. An electrode holder was placed in the duodenum lumen to elicit ascending contraction. Electrical field stimulation of the duodenal mucosa (4 Hz, 0.6 ms, 30 V) induced an ascending excitation which was blocked by hexamethonium (10 mg kg-1; n=5) and atropine (0.3 mg kg-1; n=5), but enlarged by L-NNA (10(-5) mol kg-1; n=5). CCK-8 (3 ¿ 10(-9) mol kg-1 10 min-1) blocked ascending excitation and an inhibition of the induced phasic activity was observed instead (n=18). Individually, none of the CCK receptor antagonists (L-364 718 and L-365 260) (3 ¿ 10(-7) mol kg-1; n=6 each) blocked the inhibition of ascending excitation induced by CCK-8. However, simultaneous infusion of both antagonists abolished CCK-8 effect on electrical stimulation (n=5). Similarly, none of the CCK-8 agonists (A-71623, A-71378, gastrin) modified the ascending excitation. In contrast, the simultaneous infusion of A-71623 and CCK-4 (n=4) induced an effect similar to CCK-8. In conclusion, CCK-8 blocked ascending contraction elicited by electrical field stimulation of duodenal mucosa by means of simultaneous activation of CCK-A and CCK-B receptors.

Adrenergic beta-Antagonists↗
PubMed2000

Impaired expression of the uncoupling protein-3 gene in skeletal muscle during lactation: fibrates and troglitazone reverse lactation-induced downregulation of the uncoupling protein-3 gene.

The expression of uncoupling protein (UCP)-3 mRNA in skeletal muscle is dramatically reduced during lactation in mice. The reduction in UCP-3 mRNA levels lowers the amount of the UCP-3 protein in skeletal muscle mitochondria during lactation. Spontaneous or abrupt weaning reverses the downregulation of the UCP-3 mRNA but not the reduction in UCP-3 protein levels. In lactating and virgin mice, however, fasting increases UCP-3 mRNA levels. Changes in UCP-3 mRNA occur in parallel with modifications in the levels of free fatty acids, which are reduced in lactation and are upregulated due to weaning or fasting. Modifications in the energy nutritional stress of lactating dams achieved by manipulating litter sizes do not influence UCP-3 mRNA levels in skeletal muscle. Conversely, when mice are fed a high-fat diet after parturition, the downregulation of UCP-3 mRNA and UCP-3 protein levels due to lactation is partially reversed, as is the reduction in serum free fatty acid levels. Treatment of lactating mice with a single injection of bezafibrate, an activator of the peroxisome proliferator-activated receptor (PPAR), raises UCP-3 mRNA in skeletal muscle to levels similar to those in virgin mice. 4-chloro-6-[(2,3-xylidine)-pirimidinylthio] acetic acid (WY-14,643), a specific ligand of the PPAR-alpha subtype, causes the most dramatic increase in UCP-3 mRNA, whereas troglitazone, a specific activator of PPAR-gamma, also significantly increases UCP-3 mRNA abundance in skeletal muscle of lactating mice. However, in virgin mice, bezafibrate and WY-14,643 do not significantly affect UCP-3 mRNA expression, whereas troglitazone is at least as effective as it is in lactating dams. It is proposed that the UCP-3 gene is regulated in skeletal muscle during lactation in response to changes in circulating free fatty acids by mechanisms involving activation of PPARs. The impaired expression of the UCP-3 gene is consistent with the involvement of UCP-3 gene regulation in the reduction of the use of fatty acids as fuel by the skeletal muscle and in impaired adaptative thermogenesis, both of which are major metabolic adaptations that occur during lactation.

Animals↗
PubMed2000

Report of the Spanish Gaucher's disease registry: clinical and genetic characteristics.

BACKGROUND AND OBJECTIVES: Since 1993 the demographic, clinical, analytical, genetic and follow-up data of Spanish patients with Gaucher's disease (GD) have been collected in an anonymous national database. Some statistical analyses of these data are reported concerning the distribution, clinical and genetic characteristics of GD in Spain and the response to enzyme replacement therapy (ERT) is evaluated. DESIGN AND METHODS: We performed a cohort study in Spanish GD patients by national inquiry, submitted by mail to 75 Spanish hospitals (over 300 beds) directed to internal medicine, hematology and pediatric departments. The questionnaire included 30 questions (gender, height, weight, date of birth, date of diagnosis, abode and number of relatives affected, bone crises, neurologic symptoms, other symptoms, liver and spleen size, hemoglobin, leukocyte and platelet count, tartrate resistant acid phosphatase, ALT/AST, chitotrioxidase activity, total plasma cholesterol, triglycerides, high density lipoprotein cholesterol, enzymatic activity of acid -glycosides, mutation, X-ray examination, magnetic resonance imaging-MRI-evaluation, spleen removal, and orthopedic procedures (ERT, date of first infusion). Each case with a presumed diagnosis was considered an enrolled patient. Written informed consent was obtained from all patients. The cases without enzymatic or genetic diagnosis were studied in a reference laboratory (the same for all the samples). Clinical status was evaluated by Zimran's severity score index. The enzymatic activity of acid -glycosides was determined in cellular extracts of peripheral blood granulocytes by a fluorescent method using an artificial substrate (4-methyl-umbelliferyl -D-glycoside). Polymerase chain reaction (PCR) molecular analysis was performed in DNA samples to characterize the mutations (N370S, L444P, IVS2+1, 84GG, D409H, R463C and G377S) of the glycoside genes. Two groups were created according to age at diagnosis: children under 15 years and adults, in order to evaluate clinical, genetics and follow-up. Effectiveness of ERT was evaluated using objective parameters (hemoglobin, platelets, liver and spleen size, skeletal lesions), before and after therapy. In patients under ERT, quality of life (QOL) was assessed by a SF-36 modified inquiry, including 22 questions. Statistical analysis including descriptive and frequency distribution for each variable was performed, the ANOVA test was used to identify differences between groups. Paired t-tests (before and during therapy) were carried out. The degree of linear association among measured variables was estimated by Pearson's correlation. RESULTS: By December 1999 one hundred and fifty-five patients from 117 families had been included from 66 Spanish Hospitals; the inquiry was complete for 114 patients. Mean age at diagnosis: 24.0+/-16.9 years, M/F: 72/83. No symptoms were present at diagnosis in 19.3%; visceral disease was present in 95.6% and bone disease in 62.4%. Hemoglobin levels, leukocyte and platelet counts were below the normal range in 62.3% of cases. Higher acid phosphatase levels were observed in 99% of cases; biochemical liver dysfunction tests were found in 42.9%. The test for acid glycosidase showed a marked decrease in enzymatic activity. Morphologic documentation (spleen or liver tissue, bone marrow biopsy or aspirate) of GD was obtained in 71% of the patients. The most frequent mutations observed were N370S (46.3% of the alleles detected), and L444P (18.5%). In 18.7% of the cases the disease was stable or progressing slightly; in 23.8% the spleen had been removed between 1-14 years after diagnosis and 60.6% were under ERT. Children showed both greater liver enlargement and higher SSI (p = 0.0001). There was a correlation between SSI and clinical or analytical data in adults patients for spleen size (Z: 3.142; CI: 0. 173-0.637; p= 0.0017). In 35 patients on ERT, clinical and analytic data improved as did self-evaluated QOL (p< 0.0001). (A

Adolescent↗
PubMed1999

Opposite regulation of PPAR-alpha and -gamma gene expression by both their ligands and retinoic acid in brown adipocytes.

The peroxisome proliferator-activated receptors (PPARs) are lipid-activated transcription factors involved in the regulation of lipid metabolism and adipocyte differentiation. Little is known, however, about the control of the expression of the genes encoding each of all three receptor subtypes: alpha, delta, and gamma. We have addressed this question in the brown adipocyte, the only cell type that co-expresses high levels of the three PPAR subtypes. Differentiation of brown adipocytes is associated with enhanced expression of PPAR genes. However, whereas PPARgamma and PPARdelta genes are already expressed in preadipocytes, the mRNA for PPARalpha appears suddenly in association with the acquisition of the terminally differentiated phenotype. Both retinoic acid isomers and PPAR agonists, specific for either PPARalpha or PPARgamma, regulate expression of each PPAR subtype gene in the opposite way: they up-regulate PPARalpha and down-regulate PPARgamma. The effects on PPARalpha mRNA are independent of protein synthesis, whereas inhibition of PPARgamma mRNA expression depends on protein synthesis, except when its specific ligand prostaglandin J2 is used. Our results indicate a strictly opposite autoregulation of PPAR subtypes, which supports specific physiological roles for them in controlling brown fat differentiation and thermogenic activity.

Adipocytes↗
PubMed1999

Uncoupling protein-3 gene expression in skeletal muscle during development is regulated by nutritional factors that alter circulating non-esterified fatty acids.

Uncoupling protein-3 gene expression in skeletal muscle is up-regulated during postnatal development of mice. A high-carbohydrate diet at weaning induces a decrease in uncoupling protein-3 mRNA levels that does not occur when mice were weaned onto a high-fat diet. Uncoupling protein-3 mRNA levels do not increase in response to fasting in young pups. Only after day 15 of life, when fasting increases serum non-esterified fatty acids, uncoupling protein-3 mRNA is up-regulated by starvation. Over-nutrition or under-nutrition during lactation increases or decreases, respectively, uncoupling protein-3 mRNA expression in skeletal muscle. Regulation of uncoupling protein-3 gene expression in skeletal muscle during development is mediated by ontogenic and nutritional factors determining changes in circulating non-esterified fatty acids.

Age Factors↗
PubMed1999

Both afferent and efferent nerves are implicated in cholecytokinin motor actions in the small intestine of the rat.

Cholecystokinin (CCK) regulates intestinal motility after being released by several luminal nutrients. However the mechanism of action of CCK is still not well known. The aim of our study was to establish the mechanism of action of CCK in the rat intestine using an in vivo model and focusing on the nervous pathways involved in the response as well as type of receptors. Anesthetized rats were prepared with two strain-gauges, in duodenum and jejunum, to record circular muscle motor activity. A group of animals was also prepared with a catheter to infuse capsaicin inside the duodenum. Responses to CCK-octapeptide (CCK-8) as well as to CCK agonists were studied. CCK-8 was also infused after CCK antagonists, atropine, hexamethonium or L-nitroarginine. Results show that duodenal response to CCK-8 is excitatory although inhibitory responses can be induced by gastrin. In the jejunum, CCK-8 induces an inhibitory response that is mediated by both CCK-A and -B receptors. Excitatory responses to CCK-8 are due to stimulation of preganglionic receptors while inhibitory responses are NO mediated through stimulation of postganglionic CCK-B receptors. Capsaicin locally applied in duodenal mucosa significantly decreased CCK-8 response, whereas mucosal exposure to lidocaine completely blocked CCK-8 response. In conclusion our results show that CCK response varies along the intestine according to the predominance of excitatory or inhibitory efferent innervation. Moreover, CCK-8 actions are mediated through both extrinsic and intrinsic afferent fibres.

Anesthetics, Local↗
PubMed1999

CNS wound healing is severely depressed in metallothionein I- and II-deficient mice.

To characterize the physiological role of metallothioneins I and II (MT-I+II) in the brain, we have examined the chronological effects of a freeze injury to the cortex in normal and MT-I+II null mice. In normal mice, microglia/macrophage activation and astrocytosis were observed in the areas surrounding the lesion site, peaking at approximately 1 and 3 d postlesion (dpl), respectively. At 20 dpl, the parenchyma had regenerated. Both brain macrophages and astrocytes surrounding the lesion increased the MT-I+II immunoreactivity, peaking at approximately 3 dpl, and at 20 dpl it was similar to that of unlesioned mice. In situ hybridization analysis indicates that MT-I+II immunoreactivity reflects changes in the messenger levels. In MT-I+II null mice, microglia/macrophages infiltrated the lesion heavily, and at 20 dpl they were still present. Reactive astrocytosis was delayed and persisted at 20 dpl. In contrast to normal mice, at 20 dpl no wound healing had occurred. The rate of apoptosis, as determined by using terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling, was drastically increased in neurons of ipsilateral cortex of the MT-I+II null mice. Our results demonstrate that MT-I+II are essential for a normal wound repair in the CNS, and that their deficiency impairs neuronal survival.

Animals↗
PubMed1999

Impaired inflammatory response to glial cell death in genetically metallothionein-I- and -II-deficient mice.

Metallothionein I+II (MT-I+II) are acute-phase proteins which are upregulated during pathological conditions in the brain. To elucidate the neuropathological importance of MT-I+II, we have examined MT-I+II-deficient mice following ip injection with 6-aminonicotinamide (6-AN). 6-AN is antimetabolic and toxic for bone marrow cells and grey matter astrocytes. In MT+/+ mice, injection with 6-AN resulted in breakdown of the blood-brain barrier (BBB) and absence of GFAP-positive astrocytes in specific grey matter areas of the brain stem. Reactive astrocytosis encircled the damaged grey matter areas, which were heavily infiltrated by microglia/macrophages. The recruitment of hematogenous macrophages was accompanied by leakage of the BBB. The immunoreactivity (ir) of granulocyte-macrophage-colony-stimulating factor (GM-CSF) and the receptor for GM-CSF (GM-CSFrec) was significantly upregulated in astrocytes and microglia/macrophages, respectively. MT-I+IIir was also clearly increased in astrocytes surrounding the damaged areas, while that of the CNS-specific MT isoform, MT-III, was mildly increased in both astrocytes and microglia/macrophages. In MT-/- mice injected with 6-AN, the BBB remained almost intact. The damage to specific grey matter areas was similar to that observed in MT+/+ mice, but reactive astrocytosis, microglia/macrophages infiltration, and GM-CSFir and GM-CSFrecir were clearly reduced in MT-/- mice. In contrast, MT-IIIir was dramatically increased in MT-/- mice. Total zinc decreased and histochemically detectable zinc increased in the brain stem after 6-AN similarly in MT+/+ and MT-/- mice. Bone marrow myeloid monocytes and macrophages were increased as a reaction to 6-AN only in MT+/+ mice. The results demonstrate that the capability of MT-/- mice to mount a normal inflammatory response in the brain is severely attenuated, at least in part because of 6-AN-induced bone marrow affectation, involving MT-I+II for the first time as major factors during CNS tissue damage.

6-Aminonicotinamide↗
PubMed1999

Glucagonlike peptide-1 (GLP-1) participation in ileal brake induced by intraluminal peptones in rat.

The aim of this study was to determine the mechanisms implicated in the gastrointestinal inhibition induced by ovoalbumin hydrolysate infused intraluminally. We studied the site of action, the possible implication of GLP-1, and the nervous mechanisms involved. We prepared anesthetized Sprague-Dawley rats with strain gauges in the antrum, duodenum, and proximal jejunum and a catheter in the duodenum or ileum for peptone infusion. Both intraduodenal (N = 6) and intraileal (N = 5) infusion of ovoalbumin hydrolysate induced inhibition of spontaneous motor activity in the antrum, duodenum, and proximal jejunum. Duodenal inhibition induced by intraduodenal (N = 6) or intraileal (N = 6) infusion of ovoalbumin hydrolysate was reversed by intraarterial infusion of GLP-1 receptor antagonist, exendin (9-39) (3 x 10(-8) mol/kg/40 min). Finally, a combination of the adrenergic blockers phentolamine and propranolol (1 mg/kg, each; N = 7) completely blocked inhibitory gastrointestinal motor actions caused by intraduodenal infusion of ovoalbumin hydrolysate. This study demonstrates that peptone, intraluminally infused, participates in the regulation of gastrointestinal motility through stimulation of adrenergic pathways in anaesthetized rats. Moreover, these effects are partly mediated by GLP-1 secretion. The ileum seems to be the site of action, indicating a role of GLP-1 on the ileal break mechanism.

Adrenergic alpha-Antagonists↗
PubMed1999

Retinoids and adipose tissues: metabolism, cell differentiation and gene expression.

Vitamin A derivatives (retinoids) play a key role in mammalian development and cell differentiation. Isomers of retinoic acid, the main active metabolite of vitamin A, activate retinoid receptors that act as ligand-dependent transcription factors and affect gene expression. White and brown adipose tissues are major sites of storage of vitamin A derivatives and they play an active role in whole body metabolism of retinoids. Moreover, adipose tissues are targets for the action of retinoic acid. In most cases retinoic acid impairs adipocyte differentiation although its final effects on adipose tissue development depend on retinoic acid concentration, isomers availability and expression of retinoid receptor subtypes in the white or brown adipocyte. Retinoic acid (RA) has a specific effect on brown adipose tissue, because it activates transcription of the gene for uncoupling protein-1, responsible for brown fat thermogenesis.

Adipose Tissue↗
PubMed1999

Metallothionein (MT)-III: generation of polyclonal antibodies, comparison with MT-I+II in the freeze lesioned rat brain and in a bioassay with astrocytes, and analysis of Alzheimer's disease brains.

Metallothionein-III is a low molecular weight, heavy-metal binding protein expressed mainly in the central nervous system. First identified as a growth inhibitory factor (GIF) of rat cortical neurons in vitro, it has subsequently been shown to be a member of the metallothionein (MT) gene family and renamed as MT-III. In this study we have raised polyclonal antibodies in rabbits against recombinant rat MT-III (rMT-III). The sera obtained reacted specifically against recombinant zinc-and cadmium-saturated rMT-III, and did not cross-react with native rat MT-I and MT-II purified from the liver of zinc injected rats. The specificity of the antibody was also demonstrated in immunocytochemical studies by the elimination of the immunostaining by preincubation of the antibody with brain (but not liver) extracts, and by the results obtained in MT-III null mice. The antibody was used to characterize the putative differences between the rat brain MT isoforms, namely MT-I+II and MT-III, in the freeze lesion model of brain damage, and for developing an ELISA for MT-III suitable for brain samples. In the normal rat brain, MT-III was mostly present primarily in astrocytes. However, lectin staining indicated that MT-III immunoreactivity was also present in microglia, monocytes and/or macrophages in the leptomeninges and lying adjacent to major vessels. In freeze lesioned rats, both MT-I+II and MT-III immunoreactivities increased in the ipsilateral cortex. The pattern of MT-III immunoreactivity significantly differed from that of MT-I+II, since the latter was evident in both the vicinity of the lesioned tissue and deeper cortical layers, whereas that of the former was located only in the deeper cortical layers. This suggests different roles for these MT isoforms, and indeed in a new bioassay measuring astrocyte migration in vitro, rMT-III promoted migration to a higher extent than MT-I+II. Thus, MT-III could not only affect neuronal sprouting as previously suggested, but also astrocyte function. Finally, MT-III protein levels of patients with Alzheimer's disease (AD) were, if anything, increased when compared with similarly aged control brains, which was in agreement with the significantly increased MT-III mRNA levels of AD brains.

Alzheimer Disease↗
PubMed1999

Activators of peroxisome proliferator-activated receptor-alpha induce the expression of the uncoupling protein-3 gene in skeletal muscle: a potential mechanism for the lipid intake-dependent activation of uncoupling protein-3 gene expression at birth.

The recently identified uncoupling protein-3 (UCP-3) gene, predicted to encode a new member of the family of uncoupling proteins, is preferentially expressed in skeletal muscle and has been related to phenotypes of obesity and type 2 diabetes. We have established that during mouse ontogeny, the expression of the UCP-3 gene is switched on in skeletal muscle just after birth. The induction of UCP-3 gene expression is dependent on the initiation of suckling and particularly on lipid intake. Treatment of newborn mice with activators of peroxisome proliferator-activated receptors (PPARs), such as clofibrate, bezafibrate, or (4-chloro-6-(2,3-xylidine)-pirimidinylthio)acetic acid (WY 14,643), mimics the action of food intake on UCP-3 gene expression. The specific ligand of PPAR-alpha WY 14,643 induces UCP-3 gene expression in a time- and dose-dependent manner, whereas the thiazolidinedione BRL 49653, specific for PPAR-gamma, has no effect. These treatments act without altering circulating free fatty acids. During development, skeletal muscle expresses constitutive levels of PPAR-delta mRNA, whereas expression of the PPAR-gamma gene is undetectable. PPAR-alpha gene expression is developmentally regulated in muscle as it is first expressed at birth, just before UCP-3 gene induction occurs. The induction of UCP-3 gene expression by WY 14,643 is impaired in skeletal muscle of premature neonates, which do not express PPAR-alpha. It is proposed that the UCP-3 gene is predominantly regulated in neonatal muscle by PPAR-alpha activation.

Animals↗