Edson Rodrigues

Histopathologic changes in the kidney tissue of Prochilodus lineatus Valenciennes, 1836 (Characiformes, Prochilodontidae) induced by sublethal concentration of Trichlorfon exposure

Neste trabalho foram avaliadas as alteracoes histopatologicas no tecido renal de curimbata Prochilodus lineatus, atraves de bioensaio agudo provocado pela contaminacao da agua por 0,2ml/litro de solucao de Dipterex 500 (Trichlorfon) diluido em solucao aquosa. Alteracoes comportamentais dos peixes pertencentes ao grupo contaminado, foram observadas a partir de 24 horas apos o inicio da exposicao. O tecido renal coletado apos 24 horas de exposicao apresentou aumento do espaco intercapsular com glomerulos atroficos, hipertrofia das celulas dos tubulos renais, extravasamento sanguineo a partir de capilares e areas de necrose. Apos 48 horas o tecido renal apresentou dilatacao glomerular, perda do conteudo celular do epitelio capsular parietal e da membrana basal, inchaco, vacuolizacao e granulacoes finas e grossas no citoplasma das celulas tubulares e focos de necrose acentuada.

Nitrogen metabolism of the antarctic bivalve Laternula elliptica (king & broderip) and its potential use as biomarker

The Antarctic marine environment is characterized by the extreme seasonality of the primary production in the water column and the low but stable temperatures. Both are considered the main factors in the adaptative evolution of Antarctic ectothermic organisms. Studies about physiological and biochemical processes of the cold-adapted species revealed the presence of antifreeze glycoproteins in the biological fluids and cold-adapted proteins. The low and stable temperatures have resulted in the appearence of enzymes with high catalytic efficiency and the absence of the thermal stress proteins in some Antarctic fishes. The austral winter promotes a seasonal food shortage, submitting the benthic ectotherms to long periods of starvation. This is particularly true for the organisms that depend on phytoplankton as their primary source of food. The Antarctic marine environment also presents areas of high copper concentrations on the sediment surface as well as cadmium in the water column. The bivalve Laternula elliptica, a circumpolar species, has been proposed as bioindicator for long term monitoring of heavy metals in the shallow waters of Antarctica due to its capacity to accumulate metals, especially cadmium and zinc. Like other Antarctic ectothermic organisms, L. elliptica changes its metabolism from aerobic to anaerobic as a function of temperature, being 6 oC critical and 9 oC lethal. This bivalve also shows a marked seasonality in its metabolism, with low oxygen consumption in winter as compared to summer. It is speculated that it enters into a dormancy state during the austral winter as it apparently retracts its siphons below the sediment surface. The apparent supression of the water pumping by the siphons during winter forces L. elliptica to mobilize its energy reserves, using the siphon proteins as its principal source of energy (ratio of oxygen consumption/excreted nitrogen = 3.0). Even during summer, when the high food supply stimulates the bivalve growth, the metabolism is mainly protein based. (O:N ratio = 16). The excretory nitrogen metabolism of this bivalve is typically ammoniotelic, characterized by the excretion of almost 90% of nitrogen in the form of ammonia and 10% as urea. Probably, the urea excreted arises from the hydrolysis of the proteic aminoacid L-arginine by arginase in order to maintain the tissue levels of that aminoacid. In such case, the presence of this enzyme in the kidney tissues may be related to the physiological constraints caused by the retraction of the siphons and the requirements for the excretion of this nitrogen compound during the austral winter. Studies with the renal arginase of this bivalve showed a high metabolic tolerance to the metallic cations Cu, Zn, Fe and Cd, when compared to the arginase behavior of other bivalves such as Dreissena polymorpha. The present work covers the life history of this bivalve, its potential use as a biomarker and its adaptations to the extreme marine environment conditions in Antarctica.

Arginine metabolism of the Antarctic Bivalve Laternula elliptica (King & Broderip, 1831): an ecophysiological approach

The potential aerobic ATP-generating pathway and the argininolytic capacity of the Antarctic bivalve Laternula elliptica in its main tissues were measured by the specific activity of the enzymes malate dehydrogenase (MDH), citrate synthase (CS) and arginase. The kidney showed the major potential for aerobic ATP-generating pathway and argininolytic capacity. High levels of CS and MDH activities indicated that renal tissue can be involved in activities that require a lot of energy such as excretion of metabolic end products, amino acids catabolism or even gluconeogenic activities related to inter-tissue metabolism. The fact that kidneys are the main site for arginase activity is very unusual for mollusks and could be related to the living habits of L. elliptica. Genetic expression of the L. elliptica renal arginase could be controlling the levels of l-arginine and forming urea in the excretory organ, which may not have its physiological functions directly affected by the seasonal retraction of its siphons. Compared to the bivalve Dreissena polymorpha, renal arginase of L. elliptica is more resistant to inhibition by copper and cadmium. This could be related to naturally high levels of these metals in the Antarctic marine environment and its bioaccumulation in the renal tissue of L. elliptica, as a probable advantage to its environmental adaptation. Different from other Antarctic animals that feed on Krill, the arginase of L. elliptica is much more sensitive to fluoride inhibition. However, diet composition of L. elliptica would be expected to be variable site to site and its high sensitivity to fluoride inhibition may be a matter of concern in areas near ornithogenic soils subjected to ice-melting processes.

Periodontal Therapy Effects on Nitrite Related to Oral Bacteria: A 6-Month Randomized Clinical Trial

BACKGROUNDnNitrite is a biologic factor relevant to oral and systemic homeostasis. Through an oral bacteria reduction process, it was suggested that periodontal therapy and chlorhexidine (CHX) rinse could affect nitrite levels, leading to negative effects, such as an increase in blood pressure. This 6-month randomized clinical trial evaluated the effects of periodontal therapeutic protocols on salivary nitrite and its relation to subgingival bacteria.nnnMETHODSnOne hundred patients with periodontitis were allocated randomly to debridement procedures in four weekly sections (quadrant scaling [QS]) or within 24 hours (full-mouth scaling [FMS]) in conjunction with a 60-day CHX (QS + CHX and FMS + CHX), placebo (QS + placebo and FMS + placebo), or no mouthrinse (QS + none and FMS + none) use. Real-time polymerase chain reaction determined total bacterial, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, Streptococcus oralis, and Actinomyces naeslundii levels. Salivary nitrite concentration was determined with Griess reagent. Data were analyzed statistically at baseline and 3 and 6 months by analysis of variance, Kruskal-Wallis, Mann-Whitney U, and Spearman correlation tests (P <0.05).nnnRESULTSnNitrite concentrations did not tend to change over time. Regarding CHX use, there was a negative correlation between nitrite and total bacterial load at 6 months (FMS + CHX) and one positive correlation between P. gingivalis and nitrite at baseline (QS + CHX). Independently of rinse type, in the FMS group, nitrite correlated negatively with several microbial parameters and also with a higher percentage of deep periodontal pockets.nnnCONCLUSIONSnThe relationship between nitrite and bacterial levels appears weak. Short-term scaling exhibited a greater influence on nitrite concentrations then long-term CHX use.

L-arginine metabolism in mitochondria isolated from the liver of Antarctic fish Notothenia rossii and Notothenia neglecta

The arginase tissue distribution, the biochemical properties of the argininolytic system and the subcellular localization of the enzymes carbamoylphosphate synthetase, ornithinecarbamoyl transferase, glutamine synthetase and arginase in Antarctic fish, N. neglecta and N. rossii were the main aims of the present work. The tissue with highest argininolytic activity was the kidney distal portion amounting as much as four times the specific activity of the hepatic tissue. Arginase and ornithine carbamoyltransferase were found as mitochondrial enzymes, while glutamine synthetase and carbamoylphosphate synthetase were found as cytosolic enzymes. Argininolytic assays with isolated mitochondria gave values of Kmapp for the hydrolysis of arginine 2 to 3.5 times higher than the values found for the Km with mitochondrial extracts. The effect of Mn2+ on the argininolytic activity displayed by isolated mitochondria and mitochondrial extracts, in reaction conditions near the physiological ones showed that membranes were fundamentally involved in the control of L-arginine metabolism.

Rapid responses of plants to temperature changes

ABSTRACT Temperature is one of the main environmental factors that affect plant metabolism. Considering that plants are sessile, their survival depends on the efficient activation of resistance responses to thermal stress. In this comprehensive review, we discuss recent work on rapid biochemical and physiological adjustments, herein referred to as those occurring during the first few hours or a few days after the beginning of the change in the ambient temperature. The short-term metabolic modulation after plant exposure to heat and cold, including chilling and freezing, is discussed. Effects on photosynthesis, cell membranes, antioxidant system, production of heat shock proteins and nitric oxide, as well as an overview of signaling events to heat or cold stress are presented. In addition, we also discuss the acclimation process that occurs when the plant acquires resistance to an increase or decrease in temperature, adjusting its homeostasis and steady-state physiology to the new temperatures. Finally, we present studies with tropical plants that aim at elucidating the effects of temperature and the identification of the resilience levels of these plants to the expected climate changes, and which seek the development of techniques for germplasm conservation of endangered species.

Salivary arginase activity after mechanical-chemical therapy

Introduction: Salivary components can be used as biomarkers for diagnosing and monitoring oral diseases. There is evidence that one potential biomarker, arginase, is associated with the inflammatory processes of periodontal disease, and its enzymatic activity is reduced according to the improvement in the clinical parameters after treatment. Objective: The present study aimed to evaluate the salivary arginase activity in gingivitis and periodontitis patients treated with full-mouth mechanical procedures combined with the adjunctive use of essential oils or chlorhexidine mouthwash, respectively. Material and method: Twenty-six gingivitis and 16 periodontitis patients received complete periodontal examinations at the baseline and 3 months after therapy, in which the periodontal probing depth, clinical attachment loss, plaque index, and gingival index measurements were taken. At these same appointments, the salivary total protein level and salivary arginase activity were also established via spectrophotometry. Result: There were improvements in all of the clinical parameters (p < 0.05) evaluated from the baseline to 3 months in both groups. In addition, the salivary arginase activity and total protein levels were reduced after the gingivitis treatment. Conclusion: Similar to the clinical results, both therapeutic protocols positively affected the salivary arginase activity; however, further studies are necessary to clarify its potential as a salivary biomarker for periodontal monitoring. Descriptors: Arginase; gingivitis; periodontitis; essential oils; chlorhexidine.