RESUMO
This paper is one of the first to investigate mobility in overall health using high-quality administrative data. The attractiveness of this approach lies in objective health measures and large sample sizes allowing twin analyses. I operationalize health mobility by a variety of statistics: rank-rank slopes, intergenerational correlations (IGCs) and sibling and identical twin correlations. I find rank-rank slopes and IGCs in the range 0.11-0.15 and sibling correlations in the range 0.14-0.20. Mobility in health is thus relatively high, both when compared to similar US-based studies, and when contrasted with outcomes such as educational attainment and income. Comparing sibling and identical twin correlations with parent-child associations confirms earlier findings in the literature on equality of opportunity, namely that sibling correlations capture far more variation than traditional IGCs. I conclude that 14%-38% of the variation in individual health outcomes can be attributed to family background and genes, factors which the individual cannot be held accountable for. This finding suggests that simple parent-child associations may be a poor metric for measuring health mobility.
Assuntos
Renda , Mobilidade Social , Dinamarca , Escolaridade , Humanos , Relação entre Gerações , Fatores SocioeconômicosRESUMO
OBJECTIVE: Identifying biomarkers for abdominal aortic aneurysms (AAA) could prove beneficial in prognosis of AAA and thus the selection for treatment. Microfibrillar-associated protein 4 (MFAP4) is an extracellular matrix protein that is highly expressed in aorta. MFAP4 is involved in several tissue remodeling-related diseases. We aimed to investigate the potential role of plasma MFAP4 (pMFAP4) as a biomarker of AAA. METHODS: Plasma samples and data were obtained for 504 male AAA patients and 188 controls in the Viborg Vascular (VIVA) screening trial. The pMFAP4 levels were measured by Alphalisa. The Mann-Whitney U test assessed differences in pMFAP4 levels between the presence and absence of different exposures of interest. The correlation between pMFAP4 and aorta growth rate were investigated through spearman's correlation analysis. Immunohistochemistry and multiple logistic regression adjusted for potential confounders assessed the association between pMFAP4 and AAA. Multiple linear regression assessed the correlation between pMFAP4 and aorta growth rate. Cox regression and competing risk regression were used to investigate the correlation between AAA patients with upper tertile pMFAP4 and the risk of undergoing later surgical repair. RESULTS: A significant negative correlation between pMFAP4 and aorta growth rate was observed using spearman's correlation analysis (ρ = -0.14; P = .0074). However, this finding did not reach significance when applying multiple linear regression. A tendency of decreased pMFAP4 was observed in AAA using immunohistochemistry. Competing risk regression adjusted for potential confounders indicated that patients with upper tertile pMFAP4 had a hazard ratio of 0.51 (P = .001) for risk of undergoing later surgical repair. CONCLUSIONS: High levels of pMFAP4 are associated with a decreased likelihood of receiving surgical repair in AAA. This observation warrants confirmation in an independent cohort.
Assuntos
Aneurisma da Aorta Abdominal/sangue , Aneurisma da Aorta Abdominal/cirurgia , Proteínas de Transporte/sangue , Proteínas da Matriz Extracelular/sangue , Glicoproteínas/sangue , Idoso , Aneurisma da Aorta Abdominal/diagnóstico por imagem , Biomarcadores/sangue , Dinamarca , Progressão da Doença , Humanos , Masculino , Valor Preditivo dos Testes , Estudos Prospectivos , Medição de Risco , Fatores de Risco , Fatores de Tempo , Regulação para CimaRESUMO
Objective- Porosity of the intraluminal thrombus (ILT) is believed to convey biologically active components from the bloodstream toward the aneurismal wall. Accumulation of molecules in the abdominal aortic aneurysmatic tissue may influence vascular protein turnover and regulate abdominal aortic aneurysm growth. We sought to identify proteins with concentrations in the ILT and the abdominal aortic aneurysm wall which associate with aneurysmal expansion rate. Approach and Results- Proteomic analysis by liquid chromatography tandem-mass spectrometry of separated wall and ILT samples was correlated with preoperative aneurysmal growth rate in 24 individuals operated electively for infrarenal abdominal aortic aneurysm. The median preoperative growth rate was 3.8 mm/y (interquartile range, 3) and the mean observational time was 3.3±1.7 years. Plasma components dominated the group of proteins with tissue concentrations, which correlate positively with growth rates ( P<0.001, Fisher exact test, both in the ILT and the wall). In contrast, in the wall and thrombus samples, ECM (extracellular matrix) proteins were significantly more prevalent in the group of proteins with negative correlations to growth rates ( P<0.05, Fisher exact test). Similarly, a long series of proteins, related to cellular functions correlated negatively to growth rates. Conclusions- When the preoperative aneurysmatic growth rate has been high, the concentration of many plasma proteins residing in the ILT and the aneurysmatic tissue is also high, compatible with the hypothesis of increased tissue porosity and accumulation of plasma components as a driver of aneurysm expansion. Moreover, many matrix and cellular proteins which are found in high concentrations in slower-growing aneurysms provides new knowledge about potential treatment targets.
Assuntos
Aorta Abdominal/patologia , Aneurisma da Aorta Abdominal/sangue , Aneurisma da Aorta Abdominal/patologia , Proteínas Sanguíneas/metabolismo , Idoso , Cromatografia Líquida , Feminino , Humanos , Masculino , Porosidade , Proteômica , Espectrometria de Massas em TandemRESUMO
Amylases are probably the best studied glycoside hydrolases and have a huge biotechnological value for industrial processes on starch. Multiple amylases from fungi and microbes are currently in use. Whereas bacterial amylases are well suited for many industrial processes due to their high stability, fungal amylases are recognized as safe and are preferred in the food industry, although they lack the pH tolerance and stability of their bacterial counterparts. Here, we describe three amylases, two of which have a broad pH spectrum extending to pH 8 and higher stability well suited for a broad set of industrial applications. These enzymes have the characteristic GH13 α-amylase fold with a central (ß/α)8-domain, an insertion domain with the canonical calcium binding site and a C-terminal ß-sandwich domain. The active site was identified based on the binding of the inhibitor acarbose in form of a transglycosylation product, in the amylases from Thamnidium elegans and Cordyceps farinosa. The three amylases have shortened loops flanking the nonreducing end of the substrate binding cleft, creating a more open crevice. Moreover, a potential novel binding site in the C-terminal domain of the Cordyceps enzyme was identified, which might be part of a starch interaction site. In addition, Cordyceps farinosa amylase presented a successful example of using the microseed matrix screening technique to significantly speed-up crystallization.
Assuntos
Amilases/química , Amilases/metabolismo , Fungos/enzimologia , Sítios de Ligação , Domínio Catalítico , Ativação Enzimática , Estabilidade Enzimática , Glucose/química , Glucose/metabolismo , Glicosilação , Concentração de Íons de Hidrogênio , Modelos Moleculares , Conformação Molecular , Ligação Proteica , Relação Estrutura-Atividade , alfa-Amilases/química , alfa-Amilases/metabolismoRESUMO
It is thought that the hippocampal neurogenesis is an important mediator of the antidepressant effect of electroconvulsive therapy (ECT). However, most previous studies failed to demonstrate the relationship between the increase in the hippocampal volume and the antidepressant effect. We reinvestigated this relationship by looking at distinct hippocampal subregions and applying repeated measures correlation. Using a 3 Tesla MRI-scanner, we scanned 22 severely depressed in-patients at three time points: before the ECT series, after the series, and at six-month follow-up. The depression severity was assessed by the 17-item Hamilton Rating Scale for Depression (HAMD-17). The hippocampus was segmented into subregions using Freesurfer software. The dentate gyrus (DG) was the primary region of interest (ROI), due to the role of this region in neurogenesis. The other major hippocampal subregions were the secondary ROIs (n = 20). The general linear mixed model and the repeated measures correlation were used for statistical analyses. Immediately after the ECT series, a significant volume increase was present in the right DG (Cohen's d = 1.7) and the left DG (Cohen's d = 1.5), as well as 15 out of 20 secondary ROIs. The clinical improvement, i.e., the decrease in HAMD-17 score, was correlated to the increase in the right DG volume (rrm = -0.77, df = 20, p < .001), and the left DG volume (rrm = -0.75, df = 20, p < .001). Similar correlations were observed in 14 out of 20 secondary ROIs. Thus, ECT induces an increase not only in the volume of the DG, but also in the volume of other major hippocampal subregions. The volumetric increases may reflect a neurobiological process that may be related to the ECT's antidepressant effect. Further investigation of the relationship between hippocampal subregions and the antidepressant effect is warranted. A statistical approach taking the repeated measurements into account should be preferred in the analyses.
Assuntos
Transtorno Depressivo Maior/diagnóstico por imagem , Eletroconvulsoterapia , Hipocampo/diagnóstico por imagem , Adulto , Transtorno Depressivo Maior/terapia , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Tamanho do Órgão , Resultado do TratamentoRESUMO
Calcium-dependent protein kinases play a crucial role in intracellular calcium signaling in plants, some algae and protozoa. In Plasmodium falciparum, calcium-dependent protein kinase 1 (PfCDPK1) is expressed during schizogony in the erythrocytic stage as well as in the sporozoite stage. It is coexpressed with genes that encode the parasite motor complex, a cellular component required for parasite invasion of host cells, parasite motility and potentially cytokinesis. A targeted gene-disruption approach demonstrated that pfcdpk1 seems to be essential for parasite viability. An in vitro biochemical screen using recombinant PfCDPK1 against a library of 20,000 compounds resulted in the identification of a series of structurally related 2,6,9-trisubstituted purines. Compound treatment caused sudden developmental arrest at the late schizont stage in P. falciparum and a large reduction in intracellular parasites in Toxoplasma gondii, which suggests a possible role for PfCDPK1 in regulation of parasite motility during egress and invasion.
Assuntos
Adenina/análogos & derivados , Antimaláricos/farmacologia , Cicloexilaminas/farmacologia , Regulação Enzimológica da Expressão Gênica/genética , Malária/parasitologia , Plasmodium falciparum/enzimologia , Proteínas Quinases/efeitos dos fármacos , Proteínas Quinases/genética , Proteínas de Protozoários/antagonistas & inibidores , Adenina/química , Adenina/farmacologia , Adenina/uso terapêutico , Animais , Antimaláricos/química , Antimaláricos/uso terapêutico , Células CHO , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Cricetinae , Cricetulus , Cicloexilaminas/química , Cicloexilaminas/uso terapêutico , Avaliação Pré-Clínica de Medicamentos , Ativação Enzimática/efeitos dos fármacos , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Células HeLa , Humanos , Estágios do Ciclo de Vida/efeitos dos fármacos , Malária/tratamento farmacológico , Malária/imunologia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Modelos Moleculares , Estrutura Molecular , Peso Molecular , Movimento/efeitos dos fármacos , Análise de Sequência com Séries de Oligonucleotídeos/métodos , Testes de Sensibilidade Parasitária , Plasmodium falciparum/crescimento & desenvolvimento , Proteínas Quinases/fisiologia , Proteínas de Protozoários/genética , Proteínas de Protozoários/fisiologia , Proteínas Recombinantes/antagonistas & inibidores , Proteínas Recombinantes/genética , Bibliotecas de Moléculas Pequenas , Estereoisomerismo , Relação Estrutura-Atividade , Distribuição TecidualRESUMO
AIM: The prevalence and mortality of abdominal aortic aneurysms (AAA) has been reported to decline. The aim of this study is to compare survival, prevalence, and repair rate of AAA in Denmark in the 1990s, the 2000s and the 2010s - and to examine any change in factors known to influence the prevalence. METHODS: Baseline status and up to 5-year outcomes of 34,079 general population men aged 65-74 were obtained from three RCTs; the Viborg study (1994-1998, n=4,860), the Viborg Vascular (VIVA) trial (2008-2011, n=18,748), and the Danish Cardiovascular (DANCAVAS) trial (2015-2018, n=10,471). After the millennium (VIVA and DANCAVAS) men with AAA were further offered low dose aspirin and statins. Follow-up data were not available for the DANCAVAS trial yet. RESULTS: Across the three decades, the AAA prevalence was 3.8% (Reference), 3.3% (p<0.001) and 4.2% (p=0.882), the proportion of smokers were 62%, 42% and 34% (p<0.001) amongst men with AAA, but AAA risk associations with smoking increased during the decades suggesting increased tobacco consumption of smokers. In addition, the proportions of attenders with ischemic heart disease or stroke increased significantly. The aneurysmal progression rate in the 1990s was 2.90 vs 2.98 mm/year in the 2000s (p=0.91). The need for preventive AAA repair increased insignificantly in the 2000s (Age adj. HR= 1.29, 95% C.I.: 0.95; 1.71, p=0.10), and mortality of men with screen-detected AAA was lower in the 2000s compared to the 1990s (Age-adj. HR= 0.28, 95% C.I.: 0.22; 0.36, p<0.001). CONCLUSION: The Danish prevalence of AAA today compares to the nineties. Unchanged aneurysmal progression rates combined with improved survival of men at risk of AAA leave them in longer time to develop an AAA, be diagnosed and to need later aneurysmal repair or experience rupture. CLINICAL TRIAL REGISTRATIONS: Viborg study: No possibility of registration in the nineties. VIVA: NCT00662480, URL: https://clinicaltrials.gov/show/NCT00662480, DANCAVAS: ISRCTN12157806, URL: http://www.isrctn.com/ISRCTN12157806.
RESUMO
α-Amylases are glycoside hydrolases that break the α-1,4 bonds in starch and related glycans. The degradation of starch is rendered difficult by the presence of varying degrees of α-1,6 branch points and their possible accommodation within the active centre of α-amylase enzymes. Given the myriad industrial uses for starch and thus also for α-amylase-catalysed starch degradation and modification, there is considerable interest in how different α-amylases might accommodate these branches, thus impacting on the potential processing of highly branched post-hydrolysis remnants (known as limit dextrins) and societal applications. Here, it was sought to probe the branch-point accommodation of the Alicyclobacillus sp. CAZy family GH13 α-amylase AliC, prompted by the observation of a molecule of glucose in a position that may represent a branch point in an acarbose complex solved at 2.1â Å resolution. Limit digest analysis by two-dimensional NMR using both pullulan (a regular linear polysaccharide of α-1,4, α-1,4, α-1,6 repeating trisaccharides) and amylopectin starch showed how the Alicyclobacillus sp. enzyme could accept α-1,6 branches in at least the -2, +1 and +2 subsites, consistent with the three-dimensional structures with glucosyl moieties in the +1 and +2 subsites and the solvent-exposure of the -2 subsite 6-hydroxyl group. Together, the work provides a rare insight into branch-point acceptance in these industrial catalysts.
Assuntos
Alicyclobacillus/enzimologia , alfa-Amilases/química , Acarbose , Inibidores de Glicosídeo Hidrolases , Espectroscopia de Ressonância Magnética , Amido/metabolismo , Especificidade por SubstratoRESUMO
BACKGROUND: The role of the intraluminal thrombus (ILT) in abdominal aortic aneurysm (AAA) growth remains incompletely understood. MRI is superior to other methods in depicting the morphology of the ILT. This study brings preliminary, but novel information on the presence and morphological characteristics of the ILT and AAA growth rates in a screening cohort. METHODS: Cohort study with 46 patients from the Viborg Vascular Trial. All underwent one non-contrast-enhanced magnetic resonance imaging (MRI) at the end of follow-up. ILT presence was noted and, if present, it was allocated to one of four morphological categories based on visual appearance and signal intensity on T2 weighted images. RESULTS: The mean growth rate was 1.95 mm/year ±0.87 (SD). The observation time was 5.59±0.63 (SD) years. ILT was present in AAA size groups as follows: 30-34.9 mm 20.00%, 35-39.9 mm 88.89%, 40-44.9 mm 81.25%, 45-49.9 mm 100% and 50-54.9 mm 100%. Out of 46, 8 had no ILT at the time of MRI. The presence of any sort of ILT yielded a significantly increased unadjusted and an adjusted growth rate of 1.09 mm/year (95% CI: 0.48; 1.70) and 1.24 mm/year (95% CI: 0.64; 1.83), respectively. All four thrombus types were retrospectively associated with an increased recorded growth rate compared with "no thrombus". Presence of a thin circumferential thrombus was retrospectively associated with the highest increase in growth rate, viz. 2.09 mm/year (95% CI: 1.23; 2.95). CONCLUSIONS: We observed faster growth rate in those AAA that had developed an ILT. Even faster growth was observed amongst those AAA containing a thin ILT located along the inner circumference.
Assuntos
Aorta Abdominal/diagnóstico por imagem , Aneurisma da Aorta Abdominal/diagnóstico por imagem , Angiografia por Ressonância Magnética , Trombose/diagnóstico por imagem , Idoso , Idoso de 80 Anos ou mais , Progressão da Doença , Humanos , Masculino , Valor Preditivo dos Testes , Dados Preliminares , Reprodutibilidade dos Testes , Estudos Retrospectivos , Fatores de Tempo , Ultrassonografia de IntervençãoRESUMO
Steroidogenic factor SF-1, a constitutively active nuclear hormone receptor, is essential to the development of adrenal and gonadal glands and acts as a shaping factor of sexual determination and differentiation. Its effects are exerted primarily through the control of the synthesis of steroid hormones. The functional cell-based assay Receptor Selection and Amplification Technology (R-SAT) was used to identify potent and selective SF-1 inverse agonists through the screening of a chemical library of drug-like small-molecule entities. Among them, 4-(heptyloxy)phenol (AC-45594), a prototype inverse agonist lead, was used to show that SF-1 constitutive activity can be pharmacologically modulated by a synthetic ligand. In a physiological system of endocrine function, the expression of several reported SF-1 target genes, including SF-1 itself, was inhibited by treatment with AC-45594 and analogs. Thus, pharmacological modulation of SF-1 is critical to its function as an endocrine master regulator and has potentially important consequences to diseases in which SF-1 activity is critical.
Assuntos
Enzima de Clivagem da Cadeia Lateral do Colesterol/genética , Avaliação Pré-Clínica de Medicamentos/métodos , Fenóis/farmacologia , Fator Esteroidogênico 1/agonistas , Fator Esteroidogênico 1/síntese química , Neoplasias das Glândulas Suprarrenais/patologia , Animais , Carcinoma/patologia , Proliferação de Células/efeitos dos fármacos , Enzima de Clivagem da Cadeia Lateral do Colesterol/metabolismo , AMP Cíclico/farmacologia , Genes Reporter , Humanos , Concentração Inibidora 50 , Ligantes , Luciferases/metabolismo , Camundongos , Mutação , Células NIH 3T3 , RNA Mensageiro/metabolismo , Fator Esteroidogênico 1/química , Fator Esteroidogênico 1/genética , Transcrição Gênica , Ativação Transcricional , Transfecção , Células Tumorais CultivadasRESUMO
To understand the contribution of the estrogen receptor beta, the potent and selective agonist ERb-131 was evaluated in animal models of inflammatory pain. In paradigms of acute and persistent inflammatory pain, ERb-131 did not alleviate the nociception induced by either carrageenan or formalin. However, in the chronic complete Freund's adjuvant model, ERb-131 resolved both inflammatory and hyperalgesic components. Thus, ERb-131 is sufficient to alleviate chronic but not acute inflammatory pain states.
Assuntos
Anti-Inflamatórios não Esteroides , Receptor beta de Estrogênio/agonistas , Inflamação/tratamento farmacológico , Dor/tratamento farmacológico , Doença Aguda , Animais , Carragenina , Doença Crônica , Formaldeído , Adjuvante de Freund , Hiperalgesia/induzido quimicamente , Hiperalgesia/tratamento farmacológico , Inflamação/induzido quimicamente , Inflamação/etiologia , Masculino , Dor/induzido quimicamente , Dor/etiologia , Medição da Dor/efeitos dos fármacos , Ratos , Ratos Sprague-DawleyRESUMO
The effects of estrogens on pain perception remain controversial. In animal models, both beneficial and detrimental effects of non-selective estrogens have been reported. ERb-131 a non-steroidal estrogen receptor beta ligand was evaluated in several pain animal models involving nerve injury or sensitization. Using functional and binding assays, ERb-131 was characterized as a potent and selective estrogen receptor beta agonist. In vivo, ERb-131 was devoid of estrogen receptor alpha activity as assessed in a rat uterotrophic assay. ERb-131 alleviated tactile hyperalgesia induced by capsaicin, and reversed tactile allodynia caused by spinal nerve ligation and various chemical insults. Moreover, ERb-131 did not influence the pain threshold of normal healthy animals. Thus, estrogen receptor beta agonism is a critical effector in attenuating a broad range of anti-nociceptive states.
Assuntos
Receptor beta de Estrogênio/agonistas , Dor/tratamento farmacológico , Doenças do Sistema Nervoso Periférico/tratamento farmacológico , Animais , Células Cultivadas , Relação Dose-Resposta a Droga , Estradiol/análogos & derivados , Estradiol/farmacologia , Feminino , Fulvestranto , Humanos , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Limiar da Dor/efeitos dos fármacos , Ratos , Ratos Sprague-Dawley , Útero/efeitos dos fármacosRESUMO
A series of potent and selective [1,2,4]triazolo[1,5-a]pyrimidine PDE2a inhibitors is reported. The design and improvement of the binding properties of this series was achieved using X-ray crystal structures in conjunction with careful analysis of electronic and structural requirements for the PDE2a enzyme. One of the lead compounds, compound 27 (DNS-8254), was identified as a potent and highly selective PDE2a enzyme inhibitor with favorable rat pharmacokinetic properties. Interestingly, the increased potency of compound 27 was facilitated by the formation of a halogen bond with the oxygen of Tyr827 present in the PDE2a active site. In vivo, compound 27 demonstrated significant memory enhancing effects in a rat model of novel object recognition. Taken together, these data suggest that compound 27 may be a useful tool to explore the pharmacology of selective PDE2a inhibition.
Assuntos
Exonucleases/efeitos dos fármacos , Transtornos da Memória/tratamento farmacológico , Inibidores de Fosfodiesterase/síntese química , Inibidores de Fosfodiesterase/farmacologia , Cromatografia Líquida , Humanos , Espectroscopia de Prótons por Ressonância MagnéticaRESUMO
A series of potent thienotriazolopyrimidinone-based PDE1 inhibitors was discovered. X-ray crystal structures of example compounds from this series in complex with the catalytic domain of PDE1B and PDE10A were determined, allowing optimization of PDE1B potency and PDE selectivity. Reduction of hERG affinity led to greater than a 3000-fold selectivity for PDE1B over hERG. 6-(4-Methoxybenzyl)-9-((tetrahydro-2H-pyran-4-yl)methyl)-8,9,10,11-tetrahydropyrido[4',3':4,5]thieno[3,2-e][1,2,4]triazolo[1,5-c]pyrimidin-5(6H)-one was identified as an orally bioavailable and brain penetrating PDE1B enzyme inhibitor with potent memory-enhancing effects in a rat model of object recognition memory.
Assuntos
Memória/efeitos dos fármacos , Inibidores de Fosfodiesterase/farmacologia , Cristalografia por Raios X , Descoberta de Drogas , Inibidores de Fosfodiesterase/químicaRESUMO
AvrB is a Pseudomonas syringae type III effector protein that is translocated into host plant cells during attempted pathogenesis. Arabidopsis harboring the corresponding resistance protein RPM1 can detect AvrB and mount a rapid host defense response, thus avoiding active infection. In the plant cell, AvrB induces phosphorylation of RIN4, a key component in AvrB/RPM1 recognition. Although the AvrB/RPM1 system is among the best characterized of the numerous bacterial effector/plant resistance protein systems involved in plant disease resistance and pathogenesis, the details of the molecular recognition mechanism are still unclear. To gain further insights, the crystal structure of AvrB was determined. The 2.2 A structure exhibits a novel mixed alpha/beta bilobal fold. Aided by the structural information, we demonstrate that one lobe is the determinant of AvrB/RPM1 recognition specificity. This structural information and preliminary structure-function studies provide a framework for the future understanding of AvrB function on the molecular level.
Assuntos
Proteínas de Bactérias/química , Sequência de Aminoácidos , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Cristalografia por Raios X , Modelos Moleculares , Dados de Sequência Molecular , Dobramento de Proteína , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , Pseudomonas syringae/química , Pseudomonas syringae/genética , Pseudomonas syringae/metabolismo , Alinhamento de SequênciaRESUMO
The mechanism of allosteric activation of alpha-amylase by chloride has been studied through structural and kinetic experiments focusing on the chloride-dependent N298S variant of human pancreatic alpha-amylase (HPA) and a chloride-independent TAKA-amylase. Kinetic analysis of the HPA variant clearly demonstrates the pronounced activating effect of chloride ion binding on reaction rates and its effect on the pH-dependence of catalysis. Structural alterations observed in the N298S variant upon chloride ion binding suggest that the chloride ion plays a variety of roles that serve to promote catalysis. One of these is having a strong influence on the positioning of the acid/base catalyst residue E233. Absence of chloride ion results in multiple conformations for this residue and unexpected enzymatic products. Chloride ion and N298 also appear to stabilize a helical region of polypeptide chain from which projects the flexible substrate binding loop unique to chloride-dependent alpha-amylases. This structural feature also serves to properly orient the catalytically essential residue D300. Comparative analyses show that the chloride-independent alpha-amylases compensate for the absence of bound chloride by substituting a hydrophobic core, altering the manner in which substrate interactions are made and shifting the placement of N298. These evolutionary differences presumably arise in response to alternative operating environments or the advantage gained in a particular product profile. Attempts to engineer chloride-dependence into the chloride-independent TAKA-amylase point out the complexity of this system, and the fact that a multitude of factors play a role in binding chloride ion in the chloride-dependent alpha-amylases.
Assuntos
Cloretos/metabolismo , Pâncreas/enzimologia , alfa-Amilases/química , Acarbose/metabolismo , Sequência de Aminoácidos , Substituição de Aminoácidos , Aspergillus oryzae/enzimologia , Aspergillus oryzae/genética , Ativação Enzimática/fisiologia , Humanos , Ligação de Hidrogênio , Cinética , Mutagênese , Pâncreas/metabolismo , Estrutura Terciária de Proteína , Alinhamento de Sequência , alfa-Amilases/genética , alfa-Amilases/metabolismoRESUMO
A few decades ago, chewing gum was rarely considered when industry searched for an applicable delivery vehicle for an active pharmaceutical substance. Yet, the 1980s and 1990s saw gum become the most successful nicotine delivery form; unawareness changed to cautious scepticism, and today the merits of chewing gum drug delivery technologies are generally appreciated. MediChew is the registered trademark of Fertin Pharma's medical chewing gum technology platform. Based on patent-protected technologies, it offers unique taste-masking possibilities and allows control of drug molecule release. Medical chewing gum products based on these technologies are specifically suitable for convenient administration on demand, for active substances providing a topical effect in the oral cavity and throat, and for systemic delivery of drug molecules that readily cross the oromucosal membranes.
Assuntos
Goma de Mascar , Sistemas de Liberação de Medicamentos , Excipientes , Humanos , Preparações Farmacêuticas/administração & dosagemRESUMO
The discovery that degradation and inactivation of the second messengers cAMP and cGMP are mediated by a complex enzymatic machinery has changed our perspective on cyclic nucleotide-mediated processes. In the cell, these second messengers are inactivated by no fewer than 11 distinct families of phosphodiesterases (PDEs). Much is known about the structure and function of these enzymes, their complex subcellular distribution and regulation. Yet, their potential as targets for therapeutic intervention in a broad range of endocrine abnormalities still needs to be investigated. This review explores the involvement of PDEs in the regulation of intracellular signaling and focuses on the known and potential roles that are of interest to endocrinologists.
Assuntos
Glândulas Endócrinas/fisiologia , Nucleotídeos Cíclicos/metabolismo , Diester Fosfórico Hidrolases/fisiologia , Transdução de Sinais/fisiologia , Animais , Glândulas Endócrinas/citologia , Homeostase/fisiologia , HumanosRESUMO
The development of the ovarian follicle, oocyte maturation, and ovulation require a complex set of endocrine, paracrine, and autocrine inputs that are translated into the regulation of cyclic nucleotide levels. Changes in intracellular cAMP mediate the gonadotropin regulation of granulosa and theca cell functions. Likewise, a decrease in cAMP concentration in the oocyte has been associated with the resumption of meiosis. Using pharmacological and molecular approaches, we determined that the expression of cyclic nucleotide phosphodiesterases (PDEs), the enzymes that degrade and inactivate cAMP, is compartmentalized in the ovarian follicle of all species studied, with PDE3 present in the oocytes and PDE4s in granulosa cells. The PDE3 expressed in the mouse oocyte was cloned, and the protein expressed in a heterologous system had properties similar to those of a PDE3A derived from somatic cells. Inhibition of the oocyte PDE3 completely blocked oocyte maturation in vitro and in vivo, demonstrating that the activity of this enzyme is essential for oocyte maturation. Heterologous expression of PDE3A in Xenopus oocyte causes morphological changes distinctive of resumption of meiosis (GVBD), as well as activation of mos translation and MAPK phosphorylation. Using mRNA and antibody microinjection in the Xenopus eggs, we have shown that PDE3 is downstream from the kinase PKB/Akt in the pathway that mediates IGF-1 but not progesterone-induced meiotic resumption. The presence of a similar regulatory module in mammalian oocytes is inferred by pharmacological studies with PDE3 inhibitors and measurement of PDE activity. Thus, PDE3 plays an essential role in the signaling pathway that controls resumption of meiosis in amphibians and mammals. Understanding the regulation of this enzyme may shed some light on the signals that trigger oocyte maturation.
Assuntos
Oócitos/citologia , Sistemas do Segundo Mensageiro/fisiologia , Animais , AMP Cíclico/fisiologia , Feminino , Humanos , Mamíferos , Meiose/fisiologia , Oócitos/crescimento & desenvolvimentoRESUMO
Aurora family kinases regulate important events during mitosis including centrosome maturation and separation, mitotic spindle assembly, and chromosome segregation. Misregulation of Aurora kinases due to genetic amplification and protein overexpression results in aneuploidy and may contribute to tumorigenesis. Here we report the discovery of new small molecule aminothiazole inhibitors of Aurora kinases with exceptional kinase selectivity and report a 1.7 A cocrystal structure with the Aurora B:INCENP complex from Xenopus laevis. The compounds recapitulate the hallmarks of Aurora kinase inhibition, including decreased histone H3 serine 10 phosphorylation, failure to complete cytokinesis, and endoreduplication.