Advances in enzyme bioelectrochemistry

ABSTRACT Bioelectrochemistry can be defined as a branch of Chemical Science concerned with electron-proton transfer and transport involving biomolecules, as well as electrode reactions of redox enzymes. The bioelectrochemical reactions and system have direct impact in biotechnological development, in medical devices designing, in the behavior of DNA-protein complexes, in green-energy and bioenergy concepts, and make it possible an understanding of metabolism of all living organisms (e.g. humans) where biomolecules are integral to health and proper functioning. In the last years, many researchers have dedicated itself to study different redox enzymes by using electrochemistry, aiming to understand their mechanisms and to develop promising bioanodes and biocathodes for biofuel cells as well as to develop biosensors and implantable bioelectronics devices. Inside this scope, this review try to introduce and contemplate some relevant topics for enzyme bioelectrochemistry, such as the immobilization of the enzymes at electrode surfaces, the electron transfer, the bioelectrocatalysis, and new techniques conjugated with electrochemistry vising understand the kinetics and thermodynamics of redox proteins. Furthermore, examples of recent approaches in designing biosensors and biofuel developed are presented.

Enzymatic modulation as a basis of therapeutics.

Enzyme inhibition has emerged as an important area in development of therapeutics. The basis of a large number of therapeutics used in modern day medicine for treatment of various aliments is enzyme inhibition. This review is a compilation of nearly all the therapeutic entities, currently in use, embracing almost each area of therapy including antibacterial, antifungal, antiviral, antimalarials, anticancer, antihypertensive, diuretics, antianginals, antithromboembolics, hypolipidemics, cardiotonics, anti-inflammatory, analgesics, antipyretics, antigout, antiasthamatics, antidepressants, cognition enhancers, antidiabetics, antithyroid drugs, drugs used for myasthenia gravis, peptic ulcer, parkinson’s disease, BHP, osteoarthritis, glaucoma, erectile dysfunction, septic shock, inflammation and/or neuro-degenerative disorders.

Serum enzymes changes after death & its correlation with time since death.

Estimation of time since death is one of the primary objectives of an autopsy. Forensic Scientists and researchers have been persevering hard to find out methods of accurate determination of postmortem interval since long. However, the concept of “Postmortem Clocking” so far seems to be a distant dream only. The favorite biological fluids, to study postmortem biochemical changes, have been those which withstand putrefactive changes for longer duration, like vitreous humor, cerebrospinal fluid, pericardial fluid etc. In blood, markers like electrolytes, urea, creatinine, glucose etc have been more commonly studied. Enthusiastic studies have been undertaken by various researchers to find out reasonably reliable methods of estimating postmortem interval by studying serial quantitative changes in serum levels of various enzymes and to extrapolate the data obtained therefore in terms of duration of death. However, the accuracy of such an opinion remains big area of concern even today, as the range of duration is mostly too wide to be practically useful.

Efeito do processamento do alho (Allium sativum L. ) sobre os seus compostos bioativos e potencial antioxidante in vitro e in vivo / Effect of processing of garlic (Allium sativum L. ) on their bioactive compounds and antioxidant potential in vitro and in vivo

Introdução: O aumento do consumo de frutas e hortaliças está associado à redução do risco de ocorrência de doenças crônicas não transmissíveis. Este efeito protetor tem sido atribuído particularmente à presença de vários compostos bioativos como compostos fenólicos e organosulfurados, além de fitosteróis presentes no alho que podem contribuir com os efeitos antioxidante e hipolipemiante. Porém, o processamento do alho pode acarretar mudanças na quantidade e na efetividade dos compostos bioativos. Este trabalho teve como objetivo avaliar se a cocção e a fritura do alho reduziram as concentrações de compostos bioativos, o potencial antioxidante in vitro e in vivo em hamsters hipercolesterolemizados. Métodos: In vitro - foram determinados nos alhos cru, frito e cozido: a) composição centesimal (proteínas, lipídios, cinzas, carboidratos, fibra alimentar solúvel e insolúvel); b) perfil de ácidos graxos; c) teor de fenólicos totais; d) teor de quercetina, miricetina e apigenina; e) fitosteróis; f) alicina; g) teor de cobre, zinco e selênio; h) produtos intermediários da reação de Maillard; i) potencial antioxidante utilizando os testes ORAC (Oxygen radical absorbance capacity), Rancimat® e o sistema -caroteno/ácido linoléico. In vivo - hamsters machos foram distribuidos em 5 grupos com 10 animais em cada grupo. 1 - controle; 2 - hipercolesterolêmico; 3- hipercolesterolêmico e alho cru; grupo 4 - hipercolesterolêmico e alho cozido; grupo 5 - hipercolesterolêmico e alho frito. Os animais foram eutanasiados após 4 semanas de estudo para análises do plasma e do tecido hepático. No plasma foi determinado o potencial antioxidante pelo teste ORAC, o perfil lipídico (colesterol total e frações e triacilgliceróis) e verificado a atividade das enzimas aspartato aminotransferase (AST) e alanina aminotransferase (ALT). No tecido hepático foram avaliadas a atividade das enzimas hepáticas (glutationa peroxidase, catalase e superóxido dismutase) e o potencial antioxidante utilizando dois métodos, ORAC e ensaio cometa. Resultados: In vitro - O teor de fibras totais para o alho cru foi de 10,0por cento (71,6por cento é solúvel e 28,4por cento é insolúvel). O alto conteúdo de ácidos graxos trans no alho frito (14,9por cento ) é devido ao processo de fritura com 50por cento de gordura vegetal hidrogenada. A cocção não alterou o teor dos minerais analisados.

Influência da variabilidade genética humana dos genes NAT2, CYP2E1, GSTM1 e GSTT1 na ocorrência de reações adversas hepáticas induzidas pela isoniazida em pacientes com tuberculose ativa / Influence of human genetic variability of genes NAT2, CYP2E1, GSTM1 and GSTT1 in the occurrence of hepatic adverse reactions induced by isoniazid in patients with active tuberculosis

A isoniazida (INH), uma das principais drogas usadas no esquema de tratamento de primeira linha anti-tuberculose (anti-TB), tem sido associada à intensificação de efeitos adversos principalmente hepáticos. Sabe-se hoje, que variações polimórficas em genes humanos codificando enzimas envolvidas na biotransformação de diferentes fármacos podem contribuir para diferenças interindividuais na resposta farmacológica ou toxicológica de várias drogas estando diretamente relacionadas aos desfechos de falha terapêutica e reações adversas a drogas (ADRs). A INH é geralmente administrada de forma oral sendo metabolizada por enzimas hepáticas. O mecanismo de lesão hepatocelular induzido pela isoniazida envolve as enzimas de biotransformação N-acetiltransferase 2 e a mono-oxigenase CYP450 2E1. Mutações pontuais na região codificante de NAT2 são capazes de alterar a atividade de acetilação da enzima gerando três possíveis fenótipos: acetiladores lentos, intermediários e rápidos. Os indivíduos que apresentam uma acetilação lenta acumulam intermediários hepatotóxicos levando a ocorrência de ADRs. Outra classe de enzimas cuja participação na biotransformação da isoniazida vem sendo especulada é a glutationa S-transferase (GST). Considerando a importância das variantes alélicas dos genes envolvidos na metabolização da isoniazida e que suas frequências variam entre as diferentes etnias este trabalho teve como objetivos principais: (i) análise descritiva da distribuição dos alelos de NAT2 em duas regiões diferentes do Brasil: (ii) identificação de novas mutações e caracterização haplotípica de novos alelos de NAT2 bem como análise estrutural da influência dessas alterações na estrutura protéica de NAT2 e (iii) estudo de associação, caso-controle, entre as variáveis genéticas presentes nos genes que codificam para NAT2, CYP2E1 e GSTs humanas, com a ocorrência de reações adversas em pacientes com TB em tratamento com esquemas contendo isoniazida. Dezessete SNPs previamente descritos foram identificados na população estudada, dos quais, sete: 191G maior que A; 282C maior que T; 341T maior que C; 481C maior que T; 590G maior que A; 803 maior que G e 857G maior que A são os mais frequentes na população mundial. Adicionalmente, seis mutações novas foram identificadas e sete novos alelos de NAT2 circulantes no Rio de Janeiro e/ou Goiás foram caracterizados através de clonagem e resequenciamento e experimentos de modelagem molecular. Nossos resultados mostraram a predominância de alelos de NAT2 associados com o fenótipo de acetilação lenta em indivíduos brasileiros e que a distribuição desses alelos varia significativamente de acordo com a região brasileira estudada. Além disso, fomos capazes de constatar que os acetiladores lentos apresentaram um risco significativamente maior em desenvolver hepatotoxicidade (OR: 2,62; IC 95por cento: 1,75-3.49; p igual 0.03) ou hepatite medicamentosa (OR: 3,59; IC 95por cento: 2,53-4.64; p igual 0,02) quando comparados aos acetiladores intermediários/rápidos. Por outro lado, não observamos qualquer relação entre polimorfismos nos genes CYP2E1, GSTM1 e GSTT1 com a ocorrência de ADRs durante tratamento anti-TB. Sendo assim, nossos resultados sugerem...colaterais.

Revisão sobre os valores do antígeno prostático específico e correlações com alterações da próstata / Revision about the values of the prostate-specific antigen and correlations with alterations of the prostate

Os autores fazem uma revisão bibliográfica sobre as principais causas de modificações nos valores normais do antígeno prostático específico (Prostate Specific Antigen - PSA) e suas correlações com patologias da próstata e outras causas de variações desta proteína

Why do antimicrobial agents become ineffectual?

Antibiotic resistance has evolved over the past 50 years from a merely microbiological curiosity to a serious medical problem in hospitals all over the world. Resistance has been reported in almost all species of gram-positive and -negative bacteria to various classes of antibiotics including recently developed ones. Bacteria acquire resistance by reducing permeability and intracellular accumulation, by alteration of targets of antibiotic action, and by enzymatic modification of antibiotics. Inappropriate use of an antibiotic selects resistant strains much more frequently. Once resistant bacteria has emerged, the resistance can be transferred to other bacteria by various mechanisms, resulting in multiresistant strains. MRSA is one of the typical multiresistant nosocomial pathogens. A study of the PFGE pattern of endonuclease-digested chromosomal DNA showed that MRSA of a few clones were disseminated among newborns in the NICU of a Japanese hospital. In this regard, it is important to choose appropriate antibiotics and then after some time, to change to other classes to reduce the selection of resistant strains. Since the development of epoch-making new antibiotics is not expected in the near future, it has become very important to use existing antibiotics prudently based on mechanisms of antibiotic action and bacterial resistance. Control of nosocomial infection is also very important to reduce further spread of resistant bacteria.

Fish antioxidant defenses: a comparative approach

There are few comparative studies of vertebrate antioxidant defenses (AD) in the literature. Enzymatic (superoxide dismutase, SOD, and catalase, CAT) and non-enzymatic alpha-tocopherol, beta-carotene, ubiquinol(10) and blood glutathione) antioxidant defenses were investigated in the liver and blood of 37 fish species, 15 marine species of the southeastern Brazilian coast and 22 freshwater species from the Central Amazon basin. More active marine species display in general higher concentrations of SOD and CAT in the liver and blood, compared to those of sedentary or bottom-dwelling species. AD status in marine fish may be related to the oxygen consumption of the tissues and of the whole organism, while in freshwater fish AD may be related to physical and chemical characteristics of the environment rather than to activity level. As thermoconformer organisms, most fish must routinely cope with environmental temperature changes and, consequently, with changes in their metabolic rates. The relatively high antioxidant defense levels that typify fishes, even when compared to endotherms such as birds and mammals, may protect aquatic organisms against the consequences of temperature oscillations.

Variaciones circadianas de algunas enzimas y hormonas en el cuerpo humano / Circadian rhytms of some ensymes and hormones in the human body

Desde hace algunos años, se ha estudiado con gran interés la asociación de los ritmos circadianos con la acción metabólica de las enzimas y otras moléculas. En este trabajo, se destacan algunos estudios que se han realizado en humanos para demostrar los ritmos circadianos de algunas enzimas y hormonas que son necesarias para el metabolismo, aunque también se hace referencia a las observaciones realizadas en modelos experimentales. El conocimiento de los ritmos circadianos de las enzimas y hormonas constituye una herramienta útil para la administración oportuna de medicamentos en el tratamiento de enfermedades.

Comparative studies on blood serum components and the activities of certain enzymes of non-obese and obese Egyptian women

Blood serum components and enzyme activities of 23 non-obese and 116 obese women were estimated. The obese group was categorized into two subgroups based on fat distribution [android and gynoid]. The results demonstrated that total serum proteins, globulins, uric acid and calcium to inorganic phosphorus ratio were significantly higher in obese groups in comparison with the non-obese group. Conversely, serum albumin to globulin ratio and inorganic phosphorus were significantly lower in obese groups than the non-obese women group. However, these parameters showed also that there was no significant effect on the difference between android and gynoid women groups and consequently the fat distribution had no relation with the serum constituents. The activities of alanine transaminase, aspartate transaminase, alkaline phosphatase and gamma glutamyl transferase were the same for non-obese and obese groups and also between gynoid and android groups. Conversely, significant increase of creatine phosphokinase and lactic acid dehydrogenase activities were noted in all obese groups in comparison with the non-obese group

effect of sepsis on the histochemical activity of some hepatic enzymes

The effect of sepsis, induced by caecal ligation and puncture, on the histochemical activity of some hepatic enzymes concerned with carbohydrate metabolism was studied in male rats. This activity was assessed by the staining intensity and zonal distribution of the reaction product in the livers of septic rats, the activity of glucokinase was decreased while that of phosphorylase was increased, In contrast the activity of hexokinase was not affected. These findings provided morphological basis for some of the known biochemical results of other researchers. The possible mechanisms and effects of these findings are discussed in morphobiochemical terms. A new histochemical method has been devised in this study for the demonstration of Liver glucokinase and hexokinase separately. Essentially this method depends on the use of an appropriate concentration of a substrate and a modifier

Oxygen, antioxidants and brain dysfunction

Brain is a logical target of free radical damage, considering the large lipid content of myelin sheaths and the high rate of brain oxidative metabolism. Thus, the hypothesis that free radicals may be involved in the pathogenesis of certain CNS diseases has gained increasing popularity in recent years. In CNS ischemia-reperfusion injury, the role of free radicals appears to be well established, however, involvement of other factors, such as excitatory amino acids and prostaglandins, may also contribute to the production of neuronal necrosis following ischemia. Liberation of free iron appears to play a crucial role in the generation of reactive oxygen species in posttraumatic epilepsy. Although there is no direct evidence to indicate free radical involvement in the pathogenesis of Alzheimer's disease, brain trauma with release of iron, amyloid angiopathy and disturbances in blood-brain barrier function all appear to contribute to the development of ischemic episodes with free radical generation and neuronal degeneration. In Parkinson's disease, the substantia nigra appears to be under oxidative stress as evidenced by the findings of increased lipid peroxidation, reduced GSH levels, high concentration of iron and free radical generation via autocatalytic mechanisms within neuromelanin-containing catecholaminergic neurons. Regardless of the initial insult, a cascade of events involving both reactive oxygen radicals and mitochondrial metabolism is likely to contribute to cell injury.