4 research outputs found
Mitochondrial physiology
As the knowledge base and importance of mitochondrial physiology to evolution, health and disease expands, the necessity for harmonizing the terminology concerning mitochondrial respiratory states and rates has become increasingly apparent. The chemiosmotic theory establishes the mechanism of energy transformation and coupling in oxidative phosphorylation. The unifying concept of the protonmotive force provides the framework for developing a consistent theoretical foundation of mitochondrial physiology and bioenergetics. We follow the latest SI guidelines and those of the International Union of Pure and Applied Chemistry (IUPAC) on terminology in physical chemistry, extended by considerations of open systems and thermodynamics of irreversible processes. The concept-driven constructive terminology incorporates the meaning of each quantity and aligns concepts and symbols with the nomenclature of classical bioenergetics. We endeavour to provide a balanced view of mitochondrial respiratory control and a critical discussion on reporting data of mitochondrial respiration in terms of metabolic flows and fluxes. Uniform standards for evaluation of respiratory states and rates will ultimately contribute to reproducibility between laboratories and thus support the development of data repositories of mitochondrial respiratory function in species, tissues, and cells. Clarity of concept and consistency of nomenclature facilitate effective transdisciplinary communication, education, and ultimately further discovery
Mitochondrial physiology
As the knowledge base and importance of mitochondrial physiology to evolution, health and disease expands, the necessity for harmonizing the terminology concerning mitochondrial respiratory states and rates has become increasingly apparent. The chemiosmotic theory establishes the mechanism of energy transformation and coupling in oxidative phosphorylation. The unifying concept of the protonmotive force provides the framework for developing a consistent theoretical foundation of mitochondrial physiology and bioenergetics. We follow the latest SI guidelines and those of the International Union of Pure and Applied Chemistry (IUPAC) on terminology in physical chemistry, extended by considerations of open systems and thermodynamics of irreversible processes. The concept-driven constructive terminology incorporates the meaning of each quantity and aligns concepts and symbols with the nomenclature of classical bioenergetics. We endeavour to provide a balanced view of mitochondrial respiratory control and a critical discussion on reporting data of mitochondrial respiration in terms of metabolic flows and fluxes. Uniform standards for evaluation of respiratory states and rates will ultimately contribute to reproducibility between laboratories and thus support the development of data repositories of mitochondrial respiratory function in species, tissues, and cells. Clarity of concept and consistency of nomenclature facilitate effective transdisciplinary communication, education, and ultimately further discovery
Dental caries: a proteomic approach
Doutoramento em BioQuímicaA cárie dentária é uma doença complexa que afecta uma grande parte da
população mundial independentemente do sexo, idade ou etnia. Este processo
é dependente de factores biológicos que se encontram presentes na saliva e
placa dentária. Em seguimento do referido, amostras de saliva foram
colectadas de indivíduos caracterizados em função dos índices DMFT e
DMFS. A avaliação dos convencionais parâmetros clínicos como por exemplo
fluxo salivar, capacidade tampão, pH usados na avaliação do risco para a cárie
dentária em combinação com dieta, hábitos de higiene e tabagismo foram
realizados para todos os indivíduos participantes do qual se observou a
ausência de uma positiva correlação com o índice DMFT. Uma vez que os
factores biológicos presentes na saliva influenciam o processo da cárie
dentária, o objectivo deste trabalho consistiu na investigação de uma possível
correlação entre as proteínas e peptídeos da saliva e o processo da cárie
dentária.
A caracterização das proteínas e peptídeos da saliva foi alcançada utilizando
electroforese bidimensional (2-DE), cromatografia líquida de alta resolução
(HPLC) combinada com a espectrometria de massa (MS), do qual resultou a
identificação de 38 proteínas das quais 12 foram identificadas pela primeira
vez por 2-DE e 22 peptídeos por HPLC-MS também identificados pela primeira
vez. Ensaios realizados para o estudo da composição da película dentária
seguiram a mesma metodologia descrita para a caracterização das proteínas e
peptídeos da saliva sendo realizados inicialmente in vitro e confi rmados
posteriormente por ensaios in vivo. A adsorção dos componentes salivares à
hidroxiapatite é um processo selectivo com predominância de componentes
salivares de baixo peso molecular. Contudo, amilase, lactoferrina, IgA salivar e
anidrase carbónica VI foram também identificadas. A extracção sequencial
usando guanidina e ácido trifluoroacético das proteínas/peptídeos adsorvidas à
hidroxiapatite permitiu uma avaliação da força das ligações estabelecidas.
Destes ensaios verificou-se que proteínas ricas em prolina (PRP-1/3), cistatina
S, statherina e histatina 1 estabeleciam interacções fortes com a hidroxiapatite
permanecendo adsorvidas após extracção com guanidina.
As proteínas caracterizadas da saliva e da película dentária foram
correlacionadas com o índice DMFT apresentando uma predominância de
elevadas quantidades de cistatinas, PRP -1/3, statherina e histatina 1 no grupo
de indivíduos sem cárie. O reduzido número de fragmentos em associação
com as elevadas quantidades de cistatinas podem sugerir um controle mais
eficiente da actividade proteólitica evitando desta maneira a degradação de
importantes proteínas salivares no grupo de indivíduos sem cárie. A
composição da película dentária é afectada pela composição proteica da saliva
encontrando-se as referidas proteínas em maior quantidade.
Os dados obtidos sugerem uma eficiente protecção por parte das proteínas da
saliva contra a cárie dentária em particular a PRP-1/3, statherina e histatina 1,
provavelmente devido à sua participação nos processos de remineralização na
superfície do dente, e das cistatinas na diminuição da actividade proteólitica.Dental caries is a complex disease process that affects a large proportion of
the world population, regardless of gender, age and ethnicity. This process is
dependent upon biological factors that are present within saliva and dental
plaque. Following this, whole saliva was collected from selected individuals
characterised according its DMFT and DMFS scores. Evaluation of the
conventional clinical parameters such as flow rate, buffering capacity, pH used
for caries risk assessment in combination with diet, hygiene and smoke habits
was performed for all participating subjects showing absence of a statistic
positive correlation with DMFT index. Since biological factors present on saliva
influence dental caries process, the aim of this study was to investigate how
salivary proteins and peptides are correlated with this pathology.
Characterisation of salivary proteins and peptides was achieved using twodimensional
gel electrophoresis (2-DE) and high performance liquid
chromatography (HPLC) in combination with mass spectrometry (MS) resulting
in the identification of 38 proteins, being 12 proteins identified by 2-DE and 22
peptides by HPLC-MS were identified for the first time. Experiments to study
enamel pellicle composition were performed following the same methodology
described for salivary proteins and peptides, initially in vitro being supported
with in vivo assays. Adsorption of salivary components to hydroxyapatite
showed to be a selective process with a predominance of low molecular weight
salivary components. However, amylase, lactoferrin, S-IgA, carbonic anhydrase
VI were also identified. A sequential extraction, using of guanidine and
trifluoroacetic acid, of the adsorbed proteins/peptides to hydroxyapatite allowed
to evaluate the strength of the establish interactions. From this experiments,
proline-rich proteins (PRP -1/3), cystatin S, statherin, histatin 1 exhibited a
strong interaction with hydroxyapatite remaining adsorbed after guanidine
extraction.
Characterised salivary proteins from whole saliva and enamel pellicle were
correlated with DMFT index showing a predominance of higher amounts of
cystatins, PRP-1/3, statherin and histatin 1 in caries free group. Decreased
number of fragments in association with higher amounts of cystatins may
suggest a more effective control in proteolytic activity which avoid the
degradation of important salivary proteins from caries free group. Acquired
pellicle composition is affected by whole saliva protein composition being the
above referred proteins present in higher amounts.
Obtained data suggest an effective protective role of several salivary proteins
to dental caries in particular of PRP-1/3, statherin and histatin 1, possibly due
to their participation on remineralization processes at the tooth surface, and of
cystatins probably by decreasing proteolytic activity