Role of H(2)O(2) in hypertension, renin-angiotensin system activation and renal medullary disfunction caused by angiotensin II

BACKGROUND AND PURPOSE

Activation of the intrarenal renin-angiotensin system (RAS) and increased renal medullary hydrogen peroxide (H(2) O(2) ) contribute to hypertension. We examined whether H(2) O(2) mediated hypertension and intrarenal RAS activation induced by angiotensin II (Ang II).

EXPERIMENTAL APPROACH

Ang II (200 ng·kg(-1) ·min(-1) ) or saline were infused in Sprague Dawley rats from day 0 to day 14. Polyethylene glycol (PEG)-catalase (10 000 U·kg(-1) ·day(-1) ) was given to Ang II-treated rats, from day 7 to day 14. Systolic blood pressure was measured throughout the study. H(2) O(2) , angiotensin AT(1) receptor and Nox4 expression and nuclear factor-κB (NF-κB) activation were evaluated in the kidney. Plasma and urinary H(2) O(2) and angiotensinogen were also measured.

KEY RESULTS

Ang II increased H(2) O(2) , AT(1) receptor and Nox4 expression and NF-κB activation in the renal medulla, but not in the cortex. Ang II raised plasma and urinary H(2) O(2) levels, increased urinary angiotensinogen but reduced plasma angiotensinogen. PEG-catalase had a short-term antihypertensive effect and transiently suppressed urinary angiotensinogen. PEG-catalase decreased renal medullary expression of AT(1) receptors and Nox4 in Ang II-infused rats. Renal medullary NF-κB activation was correlated with local H(2) O(2) levels and urinary angiotensinogen excretion. Loss of antihypertensive efficacy was associated with an eightfold increase of plasma angiotensinogen.

CONCLUSIONS AND IMPLICATIONS

The renal medulla is a major target for Ang II-induced redox dysfunction. H(2) O(2) appears to be the key mediator enhancing intrarenal RAS activation and decreasing systemic RAS activity. The specific control of renal medullary H(2) O(2) levels may provide future grounds for the treatment of hypertension.

Allele loss in human gastric carcinomas - relation to tumor progression and differentiation

The sequence of genetic changes associated with the development of gastric carcinoma remains unclarified despite the numerous genetic and chromosomal abnormalities that have been implicated so far in this process. We investigated the frequency and pattern of allele loss in 68 gastric carcinomas, with the aim of identifying genetic changes putatively involved in the histologic differentiation and/or progression of gastric cancer. Allele loss was investigated using 12 RFLP and 11 microsatellite markers localized at 22 different loci from 9 autosomal chromosomes. Allele loss in at least one chromosome arm was detected in 41 out of the 68 cases (60%). A high ratio of allele loss was significantly associated with the masculine gender and aneuploidy. The chromosome arms most commonly affected were 3p (57%), 17p (44%), and 6q (32%). Alterations at these chromosome arms were also frequently found (greater than or equal to 40%) in the six less advanced gastric carcinomas of the series, thus suggesting that genetic changes involving these chromosomes are early events in gastric tumorigenesis. Genetic changes at 5q and 17p loci were only observed in gastric carcinomas of the intestinal and atypical (unclassified) types, thereby indicating a possible role of genes located at these chromosome arms in the differentiation of gastric carcinoma.

Familial amyloidotic polineuropathy and systemic lupus

Familial amyloidotic polineuropathy is a genetic disorder, leading to systemic amyloid deposits, manifested as sensory-motor and autonomic neuropathy. In the Portuguese classical form, the disease is evident at a young age, and causes death if no specific treatment is received. Variability in penetrance, age of onset and clinical course has been published; environmental and genetic factors are believed to contribute to this variability. The authors report a case of a 51-year-old white female, with a medical history of acquired angioedema, late-onset familial amyloidotic polineuropathy and systemic lupus erythemathosus. The authors consider that these associated diseases could modulate their expression.

Contribution of catecholamine reactive intermediates and oxidative stress to the pathologic features of heart diseases

Pathologic heart conditions, particularly heart failure (HF) and ischemia-reperfusion (I/R) injury, are characterized by sustained elevation of plasma and interstitial catecholamine levels, as well as by the generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS). Despite the continuous and extensive research on catecholamines since the early years of the XX(th) century, the mechanisms underlying catecholamine-induced cardiotoxicity are still not fully elucidated. The role of catecholamines in HF, stress cardiomyopathy, I/R injury, ageing, stress, and pheochromocytoma will be thoroughly discussed. Furthermore and although the noxious effects resulting from catecholamine excess have traditionally been linked to adrenoceptors, in fact, several evidences indicate that oxidative stress and the oxidation of catecholamines can have important roles in catecholamine-induced cardiotoxicity. Accordingly, the reactive intermediates formed during catecholamine oxidation have been associated with cardiac toxicity, both in in vitro and in vivo studies. An insight into the influence of ROS, RNS, and catecholamine oxidation products on several heart diseases and their clinical course will be provided. In addition, the source and type of oxidant species formed in some heart pathologies will be referred. In this review a special focus will be given to the research of cardiac pathologies where catecholamines and oxidative stress are involved. An integrated vision of these matters is required and will be provided along this review, namely how the concomitant surge of catecholamines and ROS occurs and how they can be interconnected. The concomitant presence of these factors can elicit peculiar and not fully characterized responses on the heart. We will approach the existing data with new perspectives as they can help explaining several controversial results regarding cardiovascular diseases and the redox ability of catecholamines.

The reproductive biology of the rainbow runner, Elagatis bipinnulata (Quoy & Gaimard, 1825) caught in the São Pedro and São Paulo Archipelago

The rainbow runner, Elagatis bipinnulata, which belongs to the Carangidae family, has a circumtropical distribution. It is found throughout the Atlantic Ocean, from Massachusetts (USA) to Bahia (Brazil). The reproductive biology of the rainbow runner was studied, using specimens captured off the São Pedro and São Paulo Archipelago. From July 1999 to November 2003, a total of 352 fishes were analysed (201 females and 151 males). Fork length (FL) was measured and specimens were gutted for gonads collection. In the laboratory, gonads length, width and weight were measured, and sexes identified macroscopically. Through histological analysis, five different maturation stages were identified for females: immature, maturing, mature, spent and resting. A predominance of maturing and mature females was observed from January to May. The highest gonad index (GI) values were also observed during this period, ranging from 7.7 to 55. Mean sexual maturity size (L50) for females was estimated at 64.6 cm (FL). In the studied area the species exhibited total spawning, with two synchronous groups. Testicles were histologically very similar making them impossible to differentiate sexual maturation stages. Considerable variation was observed in the male gonads weight, hampering the assessment of size at maturity. However, GI values for males were also higher from January to May. These results suggest that the spawning period of the rainbow runner in the São Pedro and São Paulo Archipelago occurs during the first semester of the year.

Collection of biological samples in forensic toxicology

Forensic toxicology is the study and practice of the application of toxicology to the purposes of the law. The relevance of any finding is determined, in the first instance, by the nature and integrity of the specimen(s) submitted for analysis. This means that there are several specific challenges to select and collect specimens for ante-mortem and post-mortem toxicology investigation. Post-mortem specimens may be numerous and can endow some special difficulties compared to clinical specimens, namely those resulting from autolytic and putrefactive changes. Storage stability is also an important issue to be considered during the pre-analytic phase, since its consideration should facilitate the assessment of sample quality and the analytical result obtained from that sample. The knowledge on degradation mechanisms and methods to increase storage stability may enable the forensic toxicologist to circumvent possible difficulties. Therefore, advantages and limitations of specimen preservation procedures are thoroughfully discussed in this review. Presently, harmonized protocols for sampling in suspected intoxications would have obvious utility. In the present article an overview is given on sampling procedures for routinely collected specimens as well as on alternative specimens that may provide additional information on the route and timing of exposure to a specific xenobiotic. Last, but not least, a discussion on possible bias that can influence the interpretation of toxicological results is provided. This comprehensive review article is intented as a significant help for forensic toxicologists to accomplish their frequently overwhelming mission.