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McCune-Albright syndrome (MAS) is a rare sporadic condition defined by the classic triad of fibrous dysplasia of bone, café au lait skin macules, and hyperfunctioning endocrinopathies. The molecular basis of MAS has been ascribed to the post-zygotic somatic gain-of-function mutations in the GNAS gene, which encodes the alpha subunit of G proteins, leading to constitutive activation of several G Protein-Coupled Receptors (GPCRs). The co-occurrence of two of the above-mentioned cardinal clinical manifestations sets the diagnosis at the clinical level. In this case report, we describe a 27-month-old girl who presented with gonadotropin-independent precocious puberty secondary to an estrogen-secreting ovarian cyst, a café au lait skin macule and growth hormone, and prolactin excess, and we provide an updated review of the scientific literature on the clinical features, diagnostic work-up, and therapeutic management of MAS.
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Doenças do Sistema Endócrino , Displasia Fibrosa Poliostótica , Hormônio do Crescimento Humano , Puberdade Precoce , Feminino , Humanos , Pré-Escolar , Displasia Fibrosa Poliostótica/diagnóstico , Displasia Fibrosa Poliostótica/genética , Displasia Fibrosa Poliostótica/complicações , Puberdade Precoce/diagnóstico , Puberdade Precoce/genética , Doenças do Sistema Endócrino/complicações , Manchas Café com Leite/diagnóstico , Manchas Café com Leite/genéticaRESUMO
BACKGROUND: Nintedanib represents an antifibrotic compound able to slow down disease progression of patients with idiopathic pulmonary fibrosis (IPF). OBJECTIVE: To investigate the safety and efficacy of nintedanib in patients with IPF in a real-life setting. METHODS: This was a multicentre, retrospective, observational, real-life study for patients with IPF receiving nintedanib between October 2014 and October 2016. RESULTS: We identified 94 patients with IPF receiving nintedanib (72 males, mean age±SD: 73.8⯱â¯7.5, mean%FVC±SDâ¯=â¯68.1⯱â¯18.3, mean%DLCo±SDâ¯=â¯44.4⯱â¯14.5). Diarrhea (nâ¯=â¯52, 55.3%) was the most commonly reported adverse event. Twenty patients (21.2%) had to permanently discontinue nintedanib due to severe adverse events. In the 6-months follow-up, median decline in %FVC predicted and %DLCO predicted were 1.36 (95%Cl: 0 to 2.97) and 4.00 (95%Cl: 2.01 to 6.20), respectively, when deaths were censored and excluded from the analysis. At 12 months, mean%FVC±SD and mean%DLCo±SD were 64.5⯱â¯19.1 and 43.7⯱â¯15.4, respectively. With regards to mortality, 17 patients (18.1%) died over a study period of 730 days. CONCLUSION: Nintedanib demonstrated an acceptable safety and efficacy profile in our real-world observational study. Prospective observational studies in the context of registries that collect well-defined supporting data over time are sorely needed to answer residual questions on drug's performance.
Assuntos
Antineoplásicos/uso terapêutico , Fibrose Pulmonar Idiopática/tratamento farmacológico , Indóis/uso terapêutico , Idoso , Idoso de 80 Anos ou mais , Antineoplásicos/efeitos adversos , Progressão da Doença , Feminino , Seguimentos , Grécia , Humanos , Fibrose Pulmonar Idiopática/mortalidade , Fibrose Pulmonar Idiopática/fisiopatologia , Indóis/efeitos adversos , Masculino , Estudos Retrospectivos , Resultado do Tratamento , Capacidade VitalRESUMO
Human Angiogenin (hAng) is a member of the ribonuclease A superfamily and a potent inducer of neovascularization. Protein interactions of hAng in the nucleus and cytoplasm of the human umbilical vein cell line EA.hy926 have been investigated by mass spectroscopy. Data are available via ProteomeXchange with identifiers PXD006583 and PXD006584. The first gel-free analysis of hAng immunoprecipitates revealed many statistically significant potential hAng-interacting proteins involved in crucial biological pathways. Surprisingly, proliferating cell nuclear antigen (PCNA), was found to be immunoprecipitated with hAng only in the cytoplasm. The hAng-PCNA interaction and colocalization in the specific cellular compartment was validated with immunoprecipitation, immunoblotting, and immunocytochemistry. The results revealed that PCNA is predominantly localized in the cytoplasm, while hAng is distributed both in the nucleus and in the cytoplasm. hAng and PCNA colocalize in the cytoplasm, suggesting that they may interact in this compartment.
Assuntos
Citoplasma/metabolismo , Antígeno Nuclear de Célula em Proliferação/genética , Proteômica , Ribonuclease Pancreático/metabolismo , Linhagem Celular , Núcleo Celular/genética , Núcleo Celular/metabolismo , Citoplasma/genética , Humanos , Imunoprecipitação , Ligação Proteica/genética , Ribonuclease Pancreático/genéticaRESUMO
Osteoarthritis (OA) is the most common form of arthritis, that causes a significant decrease in the quality of life of the afflicted and constitutes a great burden for the socioeconomic system. Trace elements and heavy metals are implicated in the pathophysiology of OA, exacerbating inflammatory and oxidative stress responses. The aim of this cross-sectional study was to quantify metals in plasma samples of Greek OA patients and explore their link with disease related parameters, health status or quality of life, as well as epigenetic OA markers. This is the first study on plasma metal levels in Greek knee OA patients. To achieve precision in plasma metal and miRNA measurements, high-quality samples were selected from a subset of 34 participants (NCT04783792). Demographic, quality of life, clinical, biochemical, inflammation, oxidative stress, and anthropometric parameters, as well as microRNA levels were assessed. Significant correlations were found between circulating metals with OA related parameters or with measured microRNAs. Also, significant positive associations between plasma copper (Cu) levels and CRP (p = 0.033) or IL-6 (p = 0.001) occurred when adjusting for age, gender, BMI, physical activity level, smoking, disease severity, total arthroplasty, and dietary intake of the respective metal. Cu's role in OA is bidirectional, and this study confirms the findings that in OA, Cu is positively associated with inflammation. Such relationships between lifestyle, environment and OA enhance our understanding and encourage further study on metals related to OA inflammation.
Assuntos
MicroRNAs , Osteoartrite do Joelho , Humanos , Idoso , Cobre , Qualidade de Vida , Estudos Transversais , Grécia , Osteoartrite do Joelho/cirurgia , Biomarcadores , InflamaçãoRESUMO
Microalgae as unicellular eukaryotic organisms demonstrate several advantages for biotechnological and biological applications. Natural derived microalgae products demand has increased in food, cosmetic and nutraceutical applications lately. The natural antioxidants have been used for attenuation of mitochondrial cell damage caused by oxidative stress. This study evaluates the in vitro protective effect of Chlorella vulgaris bioactive extracts against oxidative stress in human mesenchymal stromal/stem cells (MSCs). The classical solid-liquid and the supercritical extraction, using biomass of commercially available and laboratory cultivated C. vulgaris, are employed. Oxidative stress induced by 300 µM H2O2 reduces cell viability of MSCs. The addition of C. vulgaris extracts, with increased protein content compared to carbohydrates, to H2O2 treated MSCs counteracted the oxidative stress, reducing reactive oxygen species levels without affecting MSC proliferation. The supercritical extraction was the most efficient extraction method for carotenoids resulting in enhanced antioxidant activity. Pre-treatment of MSCs with C. vulgaris extracts mitigates the oxidative damage ensued by H2O2. Initial proteomic analysis of secretome from licensed (TNFα-activated) MSCs treated with algal extracts reveals a signature of differentially regulated proteins that fall into clinically relevant pathways such as inflammatory signaling. The enhanced antioxidative and possibly anti-inflammatory capacity could be explored in the context of future cell therapies.
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Introduction: Coronavirus disease-2019 (COVID-19) presents with a variety of symptoms, but rhabdomyolysis has rarely been reported in children. Case presentation: We report a 10-year-old girl who presented with fever, myalgia, and limping. The patient was tested positive for severe acute respiratory syndrome coronavirus-2. On admission, creatine kinase (CK) level was 13 147 units per liter and the patient was diagnosed with rhabdomyolysis. She was treated with intravenous fluids, which resulted in CK levels decrease. There are currently seven case reports of children with rhabdomyolysis associated with acute COVID-19 infection and two reports with the multisystemic inflammatory syndrome. Conclusion: Children presenting with muscle pain and weakness in the acute phase or following COVID-19 infection, should alert physicians of the possibility of rhabdomyolysis.
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Sialic acids usually represent the terminal monosaccharide of glycoconjugates and are directly involved in many biological processes. The cellular concentration of their nucleotide-activated form is one pacemaker for the highly variable sialylation of glycoconjugates. Hence, the determination of CMP-sialic acid levels is an important factor to understand the complex glycosylation machinery of cells and to standardize the production of glycotherapeutics. We have established a highly sensitive strategy to quantify the concentration of nucleotide-activated sialic acid by a combination of reduction and fluorescent labeling using the fluorophore 1,2-diamino-4,5-methylenedioxybenzene (DMB). The labeling with DMB requires free keto as well as carboxyl groups of the sialic acid molecule. Reduction of the keto group prior to the labeling process precludes the labeling of nonactivated sialic acids. Since the keto group is protected against reduction by the CMP-substitution, labeling of nucleotide-activated sialic acids is still feasible after reduction. Subsequent combination of the DMB-high-performance liquid chromatography (HPLC) application with mass spectrometric approaches, such as matrix-assisted laser desorption/ionization time-of-flight-mass spectrometry (MALDI-TOF-MS) and electrospray-ionization (ESI)-MS, allows the unambiguous identification of both natural and modified CMP-sialic acids and localization of potential substituents. Thus, the described strategy offers a sensitive detection, identification, and quantification of nucleotide-activated sialic acid derivatives in the femtomole range without the need for nucleotide-activated standards.
Assuntos
Monofosfato de Citidina/metabolismo , Corantes Fluorescentes/metabolismo , Ácido N-Acetilneuramínico/metabolismo , Fenilenodiaminas/metabolismo , Animais , Núcleo Celular/metabolismo , Citosol/metabolismo , Espectrometria de Massas , Camundongos , Oxirredução , Células PC12 , RatosRESUMO
The function of the central nervous system largely depends on growth and differentiation (neurite outgrowth) of neural cells and it is well established that growth factors, especially nerve growth factor NGF stimulate neurite outgrowth. However, additional factors are implicated in this process notably the redox state of the cells. For the first time we could demonstrate that the application of recombinant thioredoxin stimulates neurite outgrowth of PC12 cells to the same extend as NGF. Thioredoxin, a small redox protein is a major player in the cellular protein reduction system. An increased expression and secretion of thioredoxin is achieved by the application of the novel sialic acid precursor N-propionylmannosamine (ManNProp). From earlier studies it is known that this N-acylmannosamine analog stimulates significantly the neurite outgrowth in cell cultures. This finding would give new insights into the mechanism of the nerve-stimulatory action of ManNProp and demonstrates the novel role of thioredoxin during the regulation of nerve growth, encouraging further studies.
Assuntos
Hexosaminas/metabolismo , Neuritos/fisiologia , Neurogênese , Tiorredoxinas/metabolismo , Animais , Hexosaminas/farmacologia , Neuritos/efeitos dos fármacos , Neuritos/metabolismo , Células PC12 , RatosRESUMO
Entire Helicobacter Pylori Neutrophil Activated Protein (HPNAP) and its truncated forms NH(2)-terminal region HPNAP(1-57) and C-terminal region HPNAP(58-144) after cloning into pET29c vector, purification and removal of LPS traces were subjected to human neutrophil activation. Our results revealed that the C-terminal region of HPNAP is indispensable for human neutrophil stimulation and their further adhesion to endothelial cells - a step necessary to H. pylori inflammation - in a ratio equal to that exhibited by the entire protein. In addition, experiments concerning the implication of Arabino-Galactan-Proteins (AGPs) derived from Chios Mastic Gum (CMG), the natural resin of the plant Pistacia lentiscus var. Chia revealed the inhibition of neutrophil activation and therefore their adhesion to endothelial cells, in vitro. Both, the involvement of HPNAP C-terminal region in stimulation-adhesion of neutrophils to endothelial cells as well as the inhibition of this process by AGPs have to be further investigated and may be exploited in a future anti-inflammatory therapy for H. pylori patients.
Assuntos
Proteínas de Bactérias/imunologia , Adesão Celular , Células Endoteliais/fisiologia , Helicobacter pylori/imunologia , Neutrófilos/imunologia , Humanos , Recém-NascidoRESUMO
In the quest for the rational design of selective and potent inhibitors for members of the pancreatic ribonuclease A (RNase A) family of biomedical interest, the binding of uridine 5'-phosphate (U5P) and uridine 5'-diphosphate (UDP) to RNase A have been investigated using kinetic studies and X-ray crystallography. Both nucleotides are competitive inhibitors of the enzyme, with K(i) values of 4.0 and 0.65 mM, respectively. They bind to the active site of the enzyme by anchoring two molecules connected to each other by hydrogen bonds and van der Waals interactions. While the first of the inhibitor molecules binds with its nucleobase in the pyrimidinyl-binding subsite, the second is bound at the purine-preferring subsite. The unexpected binding of a pyrimidine at the purine-binding subsite has added new important elements to the rational design approach for the discovery of new potent inhibitors of the RNase A superfamily.
Assuntos
Desenho de Fármacos , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Ribonuclease Pancreático/antagonistas & inibidores , Nucleotídeos de Uracila/metabolismo , Animais , Bovinos , Cristalografia por Raios X , Ligação de Hidrogênio/efeitos dos fármacos , Modelos Moleculares , Eletricidade Estática , Homologia Estrutural de Proteína , Difosfato de Uridina/metabolismoRESUMO
Sialic acid (Sia) is expressed as terminal sugar in many glycoconjugates and plays an important role during development and regeneration. Addition of homopolymers of Sia (polysialic acid; polySia/PSA) is a unique and highly regulated post-translational modification of the neural cell adhesion molecule (NCAM). The presence of polySia affects NCAM-dependent cell adhesion and plays an important role during brain development, neural regeneration, and plastic processes including learning and memory. PolySia-NCAM is expressed on several neuroendocrine tumors of high malignancy and correlates with poor prognosis. Two closely related enzymes, the polysialyltransferases ST8SiaII and ST8SiaIV, catalyze the biosynthesis of polySia. This review summarizes recent knowledge on Sia biosynthesis and the correlation between Sia biosynthesis and polysialylation of NCAM and report on approaches to modify the degree of polySia on NCAM in vitro and in vivo. First, we describe the inhibition of polysialylation of NCAM in ST8SiaII-expressing cells using synthetic Sia precursors. Second, we demonstrate that the key enzyme of the Sia biosynthesis (UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase) regulates and limits the synthesis of polySia by controlling the cellular Sia concentration.
Assuntos
Adesão Celular/fisiologia , Moléculas de Adesão de Célula Nervosa/fisiologia , Ácidos Siálicos/metabolismo , Animais , Técnicas In Vitro , Ácidos Siálicos/biossíntese , Ácidos Siálicos/classificaçãoRESUMO
The cause of the molecular defect of Fanconi anemia (FA) remains unknown. Cells from patients with FA exert an elevated spontaneous chromosomal instability which is further triggered by mitomycin C. The induced lability is reduced by overexpression of thioredoxin which is not the case for spontaneous instability. However, both are eliminated by overexpression of thioredoxin cDNA with an added nuclear localization signal. This implies that thioredoxin is lacking in the nuclei of FA cells. The total thioredoxin content in all FA cells tested is reduced. The resultant lack of nuclear thioredoxin can be the explanation for the major symptomatology in FA. Since thioredoxin is known to be the reactive cofactor of ribonucleotid reductase its shortcoming reduces the supply of deoxyribonucleotides thus hindering the DNA and replication repair with resultant chromosomal breaks. Furthermore, depression of tyrosine hydroxylase, the key enzyme of melanine synthesis, could be the basis for the pathognomotic 'café au lait' spots of FA. The observation of thioredoxin reduction in FA cells permits insight into the molecular phathophysiology of FA.
Assuntos
Aberrações Cromossômicas , Anemia de Fanconi/genética , Tiorredoxinas/metabolismo , Transporte Ativo do Núcleo Celular , Núcleo Celular/metabolismo , Núcleo Celular/ultraestrutura , Células Cultivadas , Anemia de Fanconi/metabolismo , Fibroblastos/metabolismo , Fibroblastos/ultraestrutura , Humanos , Testes para Micronúcleos , Sinais de Localização Nuclear , RNA/biossíntese , Proteínas Recombinantes de Fusão/metabolismo , Tiorredoxinas/genética , TransfecçãoRESUMO
Cancer cells have high levels of thioredoxin (Trx) and of glyceraldehyde 3-phosphate dehydrogenase (GAPDH). Cells from patients with the cancer-prone disease Fanconi anemia (FA) exhibit reduced Trx levels. We found the activity of GAPDH to correlate directly with the endogenous Trx content and mRNA transcripts for GAPDH and TRx reduced in FA cells. The treatment of cells with reduced human Trx stimulated the synthesis of GAPDH mRNA. Similarly, the transfection of cells with an expression plasmid for Trx increased GAPDH mRNA synthesis. Trx treatment of cells and subsequent analysis of the differential gene expression by human cDNA arrays containing about 50 000 different PCR products resulted in more than 300 up- or downregulated genes. Two representative genes, GAPDH and IkappaBalpha/MAD-3, were further investigated to confirm their stimulation by Trx. Trx besides being the major carrier of redox potential of cells is also a regulator of gene expression on the transcriptional level. By regulation via Trx, cells are able to adapt to the prevailing redox conditions. These findings also enlighten the pathophysiology of FA in the respect that the characteristic diminution of Trx that results in the dysregulation of gene expression is a basis for the major symptoms of this disease.
Assuntos
Regulação da Expressão Gênica , Tiorredoxinas/genética , Tiorredoxinas/metabolismo , Northern Blotting , Western Blotting , Extratos Celulares , Linhagem Celular Transformada , Células Cultivadas , Fibroblastos/citologia , Gliceraldeído-3-Fosfato Desidrogenase (Fosforiladora)/metabolismo , Humanos , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
Werner's syndrome is a rare disease of premature ageing. The WRN gene product defective in this disorder belongs to the RecQ helicase family and is thought to be involved in DNA metabolism. Another protein, which plays an important role in both DNA replication and repair, is the poly-ADP ribosyl transferase. Here we demonstrate an interaction of these two proteins resulting in ADP-ribosylation of the WRN protein. These results imply that WRN is involved in DNA replication and in DNA repair.
Assuntos
DNA Helicases/metabolismo , Poli(ADP-Ribose) Polimerases/metabolismo , Western Blotting , Linhagem Celular , DNA Helicases/fisiologia , Reparo do DNA , Replicação do DNA , Exodesoxirribonucleases , Glicosilação , Humanos , Poli(ADP-Ribose) Polimerases/análise , Testes de Precipitina , Ligação Proteica , RecQ Helicases , Síndrome de Werner/enzimologia , Síndrome de Werner/patologia , Helicase da Síndrome de WernerRESUMO
Haemostasis depends on the balanced participation of von Willebrand factor (vWF), a large multimeric and multidomain glycoprotein with essential role during the initial steps of blood clotting. Mature vWF circulates in plasma with the form of multimers comprised of several domains with diverse functions. More specifically, the A1 domain of vWF plays crucial role in haemostasis, regulating the mechanism of platelet adhesion in sites of vascular injury while A2 domain regulates the normal turnover of vWF. Recent studies have implied that an intramolecular interaction between A1 and A2 domains exists, which prevents platelets adhesion and subsequently inhibits the initial step of the blood coagulation mechanism. In an effort to elucidate the essential nature of the interaction between these two domains, we produced and purified the corresponding recombinant unmodified polypeptides. The secondary structure of the two domains was studied individually and as a mixture using circular dichroism spectroscopy. The observed interaction was verified by ELISA competition assays using antibodies and their ability to form productive interactions was further characterized kinetically. In silico analysis (docking and molecular dynamics simulations) of the A1-A2 binding indicated three possible structural models highlighting the crucial, for this interaction, region.
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Fator de von Willebrand/química , Fator de von Willebrand/metabolismo , Células Cultivadas , Dicroísmo Circular , Ensaio de Imunoadsorção Enzimática , Humanos , Simulação de Dinâmica Molecular , Ligação Proteica , Conformação ProteicaRESUMO
Legumes and the polyphenolic compounds present in them have gained a lot of interest due to their beneficial health implications. Dietary polyphenolic compounds, especially flavonoids, exert antioxidant properties and are potent inhibitors of xanthine oxidase (XO) activity. XO is the main contributor of free radicals during exercise but it is also involved in pathogenesis of several diseases such as vascular disorders, cancer and gout. In order to discover new natural, dietary XO inhibitors, some polyphenolic fractions and pure compounds isolated from two legume plant extracts were tested for their effects on XO activity. The fractions isolated from both Vicia faba and Lotus edulis plant extracts were potent inhibitors of XO with IC(50) values range from 40-135 µg/mL and 55-260 µg/mL, respectively. All the pure polyphenolic compounds inhibited XO and their K(i) values ranged from 13-767 µM. Ten of the compounds followed the non competitive inhibitory model whereas one of them was a competitive inhibitor. These findings indicate that flavonoid isolates from legume plant extracts are novel, natural XO inhibitors. Their mode of action is under investigation in order to examine their potential in drug design for diseases related to overwhelming XO action.
Assuntos
Inibidores Enzimáticos/farmacologia , Fabaceae/metabolismo , Flavonoides/química , Glicosídeos/química , Extratos Vegetais/farmacologia , Xantina Oxidase/antagonistas & inibidores , Xantina Oxidase/química , Animais , Antioxidantes/química , Bovinos , Química Farmacêutica/métodos , Suplementos Nutricionais , Desenho de Fármacos , Humanos , Concentração Inibidora 50 , Cinética , Lotus/metabolismo , Modelos Químicos , Modelos Estatísticos , Folhas de Planta/metabolismo , Polifenóis/química , Vicia faba/metabolismoRESUMO
Glycogen phosphorylase is a molecular target for the design of potential hypoglycemic agents. Structure-based design pinpointed that the 3'-position of glucopyranose equipped with a suitable group has the potential to form interactions with enzyme's cofactor, pyridoxal 5'-phosphate (PLP), thus enhancing the inhibitory potency. Hence, we have investigated the binding of two ligands, 1-(ß-d-glucopyranosyl)5-fluorouracil (GlcFU) and its 3'-CH(2) OH glucopyranose derivative. Both ligands were found to be low micromolar inhibitors with K(i) values of 7.9 and 27.1 µm, respectively. X-ray crystallography revealed that the 3'-CH(2) OH glucopyranose substituent is indeed involved in additional molecular interactions with the PLP γ-phosphate compared with GlcFU. However, it is 3.4 times less potent. To elucidate this discovery, docking followed by postdocking Quantum Mechanics/Molecular Mechanics - Poisson-Boltzmann Surface Area (QM/MM-PBSA) binding affinity calculations were performed. While the docking predictions failed to reflect the kinetic results, the QM/MM-PBSA revealed that the desolvation energy cost for binding of the 3'-CH(2) OH-substituted glucopyranose derivative out-weigh the enthalpy gains from the extra contacts formed. The benefits of performing postdocking calculations employing a more accurate solvation model and the QM/MM-PBSA methodology in lead optimization are therefore highlighted, specifically when the role of a highly polar/charged binding interface is significant.
Assuntos
Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Glucose/análogos & derivados , Glicogênio Fosforilase/antagonistas & inibidores , Glicogênio Fosforilase/metabolismo , Hipoglicemiantes/química , Hipoglicemiantes/farmacologia , Cristalografia por Raios X , Diabetes Mellitus Tipo 2/tratamento farmacológico , Diabetes Mellitus Tipo 2/enzimologia , Desenho de Fármacos , Glicogênio Fosforilase/química , Humanos , Simulação de Dinâmica Molecular , TermodinâmicaRESUMO
C5 halogen substituted glucopyranosyl nucleosides (1-(ß-D-glucopyranosyl)-5-X-uracil; X=Cl, Br, I) have been discovered as some of the most potent active site inhibitors of glycogen phosphorylase (GP), with respective K(i) values of 1.02, 3.27, and 1.94 µM. The ability of the halogen atom to form intermolecular electrostatic interactions through the σ-hole phenomenon rather than through steric effects alone forms the structural basis of their improved inhibitory potential relative to the unsubstituted 1-(ß-D-glucopyranosyl)uracil (K(i) =12.39 µM), as revealed by X-ray crystallography and modeling calculations exploiting quantum mechanics methods. Good agreement was obtained between kinetics results and relative binding affinities calculated by QM/MM-PBSA methodology for various substitutions at C5. Ex vivo experiments demonstrated that the most potent derivative (X=Cl) toward purified GP has no cytotoxicity and moderate inhibitory potency at the cellular level. In accordance, ADMET property predictions were performed, and suggest decreased polar surface areas as a potential means of improving activity in the cell.
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Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Glicogênio Fosforilase/antagonistas & inibidores , Nucleosídeos/química , Domínio Catalítico , Linhagem Celular , Cristalografia por Raios X , Avaliação Pré-Clínica de Medicamentos/métodos , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/farmacocinética , Halogênios/química , Humanos , Cinética , Ligantes , Modelos Moleculares , Estrutura Molecular , Fosforilase b/antagonistas & inibidores , Eletricidade Estática , Relação Estrutura-AtividadeRESUMO
Sialic acids represent a family of 9-carbon acidic amino sugars expressed mainly as terminal monosaccharides on most mammalian glycoconjugates. Sialic acids play an outstanding role during cellular processes, such as development and regeneration, as they are involved in a variety of molecular interactions. Sialic acids are synthesized in the cytosol starting from UDP-N-acetylglucosamine by the UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine-kinase (GNE), which is the key enzyme in the biosynthesis of sialic acid that catalyzes the generation of N-acetylmannosamine, which in turn is an intermediate of the sialic acid pathway that represents the natural molecular precursor of all sialic acids. Of increasing interest are the influence of the sialic acid precursor N-acetylmannosamine (or related N-acylmannosamines), GNE, and sialic acids themselves on cellular processes such as proliferation, gene expression, or cell differentiation. Here, we present recent data and review indications that N-acylmannosamines (the direct precursors of all sialic acids) may act as signaling molecules, and that the key enzyme of the sialic acid metabolism is directly involved in the regulation of cell proliferation and cell differentiation.
Assuntos
Diferenciação Celular , Ácido N-Acetilneuramínico/metabolismo , Transdução de Sinais , Animais , Glicosilação , Humanos , Ácido N-Acetilneuramínico/biossíntese , Células PC12 , Processamento de Proteína Pós-Traducional , RatosRESUMO
Time- and dose-dependent measurements of metabolites of galactose (with glucose as control) in various organs of rats are discussed. Not only the liver but especially the brain and to a lesser extent the muscles also have the capacity to take up and metabolize galactose. Primarily, the concentrations of UDP-galactose, a pivotal compound in the metabolism of galactose, and UDP-glucose are measured. An important feature lies in the demonstration that galactose and glucose are metabolized to amino acids and that the only increases observed in the brain appear in the concentrations of glutamate, glutamine, GABA measured after acute galactose loads. In addition the increase in the amino acid concentrations after galactose has been administered persists for longer periods of time than after glucose administration. This conversion of hexoses, especially galactose, to amino acids requires the consumption of ammonia equivalents in the brain; this finding might stimulate the use of galactose as a new means of removal of this neurotoxic compound from the brain in patients suffering from hepatic encephalopathy or Alzheimer's disease.