Cardioprotective effect of ischemic preconditioning is preserved in food-restricted senescent rats

Ischemic preconditioning (PC) has been proposed as an endogenous form of protection against-ischemia reperfusion injury. We have shown that PC does not prevent postischemic dysfunction in the aging heart. This phenomenon could be due to the reduction of cardiac norepinephrine release, and it has also been previously demonstrated that age-related decrease of norepinephrine release from cardiac adrenergic nerves may be restored by caloric restriction. We investigated the effects on mechanical parameters of PC against 20 min of global ischemia followed by 40 min of reperfusion in isolated hearts from adult (6 mo) and "ad libitum"-fed and food-restricted senescent (24 mo) rats. Norepinephrine release in coronary effluent was determined by high-performance liquid chromatography. Final recovery of percent developed pressure was significantly improved after PC in adult hearts versus unconditioned controls (85.2 +/- 19% vs. 51.5 +/- 10%, P < 0.01). The effect of PC on developed pressure recovery was absent in ad libitum-fed rats, but it was restored in food-restricted senescent hearts (66.6 +/- 13% vs. 38.3 +/- 11%, P < 0.05). Accordingly, norepinephrine release significantly increased after PC in both adult and in food-restricted senescent hearts, and depletion of myocardial norepinephrine stores by reserpine abolished the PC effect in both adult and in food-restricted senescent hearts. We conclude that PC reduces postischemic dysfunction in the hearts from adult and food-restricted but not in ad libitum-fed senescent rats. Despite the possibility of multiple age-related mechanisms, the protection afforded by PC was correlated with increased norepinephrine release, and it was blocked by reserpine in both adult and food-restricted senescent hearts. Thus caloric restriction may restore PC in the aging heart probably via increased norepinephrine release.     

Ischemic preconditioning changes the pattern of coronary reactive hyperemia regardless of mitochondrial ATP-sensitive K(+) channel blockade

Ischemic preconditioning increases the velocity of vasodilatation and reduces the total hyperemic flow (THF) of a subsequent coronary reactive hyperemia (CRH). The increase in the velocity of vasodilatation has been shown to depend on an up-regulation of the endothelial release of nitric oxide, while the reduction of THF is attributed to an adenosine A(1) receptor-mediated mechanism. We investigated whether the changes in CRH induced by preconditioning ischemia (PI) can still be obtained after blockade of mitochondrial ATP-sensitive K(+) channels by sodium 5-hydroxydecanoate (5-HD), and whether the blockade per se affects the pattern of CRH.In anesthetized goats, flow was recorded from the left circumflex coronary artery (LCCA). CRH was obtained with the occlusion of LCCA for 15 s. PI was obtained by 2 cycles of 2.5 min of LCCA occlusion with a 5 min interval of reperfusion between the two occlusions. CRH was studied before and after i.v. administration of 5-HD (20 mg/kg), as well as in the presence of 5-HD after PI. Following 5-HD, the pattern of CRH remained unchanged. After 5-HD and PI, velocity of vasodilatation and total hyperemic flow of CRH showed the same changes as in previous studies after PI alone. It was concluded that the blockade of mitochondrial ATP-sensitive K(+) channels, which is reported to prevent myocardial protection, does not affect CRH and does not prevent PI from increasing the velocity of vasodilatation and reducing THF. These results demonstrate that the changes induced in CRH by preconditioning are independent of the opening of the mitochondrial ATP-sensitive K(+) channels.     

Tobacco-smoke exposure indicators and urinary mutagenicity

The protective effect of calcium given orally by gavage with two doses (40 and 80mg/kg body weight) was evaluated against clastogenecity induced by lead acetate with two concentrations (200 and 400mg/kg diet) on bone marrow and spermatocyte cells of mice in vivo. The parameter screened was percentage of chromosomal aberrations with and without gaps and sperm abnormalities. Statistical analyses indicated the protection efficacy of calcium with the high dose rather than the other in both types of mouse cells.The observation from the laboratory tests, dealing that lead acetate can be considered as an environmental genotoxic material. We recommended that it must be administered of calcium (as calcium chloride) as a protective agent to reduce the genotoxic effect of lead in the somatic and germ cells.     

Vegetation dynamics of south-western Italy in the last 28 kyr inferred from pollen analysis of a Tyrrhenian Sea core

A continuous pollen record covering the last 28 kyr was obtained from core C106 collected in the Bay of Salerno in the southern Tyrrhenian Basin, seven radiocarbon dates and the recognition of two tephra layers (Y3 and Pompeii Pumice) providing good chronological constraints. The clear climatic signal given by the pollen spectra integrated by isotopic data, combined with comparisons with other Mediterranean sites, allowed the Last Glacial, Late Glacial and Holocene periods to be distinguished in the core. In particular, the Last Glacial period is characterised by large quantities of herbaceous and steppe elements such as Artemisia. The beginning of the Late Glacial has been correlated with the first increase of deciduous Quercus and the reduction of steppe and herbaceous elements. The Younger Dryas event is recorded only by oxygen isotopes while the vegetation does not seem to change, as in other Mediterranean sites. The Holocene corresponds to rich deciduous and evergreen forests. The first features which could be interpreted as signs of human presence are represented by a few grains of Juglans, Castanea and cereal-type while intensive olive cultivation and deforestation seem to fall within the Middle Ages. Received October 10, 2001 / Accepted June 20, 2002 Correspondence to: Elda Russo Ermolli     

Determination of organophosphorus pesticide residues in human tissues by capillary gas chromatography-negative chemical ionization mass spectrometry analysis

We describe an analytical method that allows the determination of organophosphorus pesticides (OPs) in different human tissues. It involves an extraction procedure with ethanol-ethyl acetate, followed by gel permeation chromatography clean-up step and analysis by capillary gas chromatography-negative chemical ionization mass spectrometry in the selected ion monitoring mode. The method was tested for 37 OPs and the recoveries obtained vary between 60 and 106% with standard deviations ranging between +/-2 and +/-10. These values are independent of the analyzed tissue. Peak area repeatability as RSD for some OPs was < or =4.8% while a good linear relationship in the range 1.0-500 pg microl(-1) with r(2)> or =0.9878 was obtained. The limit of detection for the 37 OPs falls between 0.01 and 0.09 ng g(-1) with an RSD< or =9.5%. The analytical set up in this paper has been used to analyze different samples of human tissues (liver, healthy kidney, cancer kidney and adipose tissue) of 24 patients. The number of the identified OPs in the tissue samples is different (max. 20) according to the sample while their concentration ranges between the limit of detection and 28.0 ng g(-1). The highest concentrations have been determined in liver samples without any pathology (0.4-28.0 ng g(-1)) while the lowest concentrations have been determined in healthy kidney samples (0.01-1.50 ng g(-1)). In the cancer kidney samples OP concentrations vary between 0.03 and 4.6 ng g(-1): these concentrations are more elevated than those determined in healthy kidney samples. The comparison between the concentration of OPs determined in the healthy part, when possible, and those determined in the cancer part of the same kidney sample are very interesting: in fact, in the latter the OP concentration is generally 1-2-times higher than that in the former, an index of lower enzymatic activity in the cancer tissue.     

Effect of 2,4-D and 4-CPPU on somatic embryogenesis from stigma and style transverse thin cell layers of Citrus

Callus induction, somatic embryogenesis and plant regeneration were obtained in lemon [Citrus limon (L.) Burm. cv `Femminello'] and sweet orange [C. sinensis (L.) Osb. cv `Washington Navel GS'] from cultures of stigma and style transverse thin cell layer explants [(t)TCLs]. Explants were cultured on 16 different media, based on the nutrients and vitamins of Murashige and Tucker medium (MT) supplemented with different combinations of 2,4-dichlorophenoxyacetic acid (2,4-D) and N-(2-chloro-4-pyridyl)-N-phenylurea (4-CPPU). Sucrose (146 mM) was used as the sole carbon source. Somatic embryos arose from callus at the surface of stigma and style (t)TCLs 3–5 months after culture initiation of both sweet orange and lemon. The percentages of embryo formation from style (t)TCLs ranged from 0% (the media containing 2,4-D) to 16.0% (the medium supplemented with 4 M 4-CPPU) for C. limon. Better results were obtained when stigma (t)TCLs from C. limon were used; in fact, percentages ranged from 0% on the media containing 2,4-D, with the only exception for the medium supplemented with 0.4 M 2,4-D, to 24.8% on medium with 4 M 4-CPPU. The embryogenic response of lemon (t)TCLs was usually higher than for sweet orange (t)TCLs. After about 3 months, somatic embryos developed into plantlets at high frequencies ranging from 53% to 75% for sweet orange and lemon style derived embryos, respectively.     

beta-Endorphin modulation of pressor response to hyperventilation in hypertensive patients

After hyperventilation, systolic and diastolic blood pressure (BP) significantly decreased in 14 hypertensive patients (group 1), did not change in 9 (group 2) and increased in 8 (group 3). Basal BP, norepinephrine and dynorphin B levels were higher in group 1 than in groups 2 and 3. The decrease in BP after hyperventilation was associated with a decrease in plasma norepinephrine, Met-enkephalin and dynorphin B and an increase in beta-endorphin. Naloxone abolished the hyperventilation-induced BP and norepinephrine decreases. Our findings indicate that hyperventilation may select hypertensive patients with different sympatho-adrenergic activity and that the increase in beta-endorphin reduces BP response to hyperventilation in patients with high sympatho-adrenergic tone.     

Glutathione transferase isoenzymes from frog (Xenopus laevis) liver and embryo

The expression of glutathione transferase isoenzymes has been investigated in embryo and adult liver of the frog Xenopus laevis. By analysing the GST isoenzymes recovered from GSH-affinity chromatography in terms of electrophoretic mobility, HPLC elution profile, immunological reactivity, N-terminal amino acid sequence and mass spectrometry molecular mass no significant difference in the GST subunit composition between embryos and liver was found. In both tissues the same three subunits, showing similarity to mu, alpha and sigma class GSTs, are present. These results, together with those previously reported for toad (Bufo bufo), strongly support the notion that the transition from an aquatic environment to a terrestrial atmosphere containing high oxygen concentration has accompanied specific GST gene expression.     

Physiological thiols as promoters of glutathione oxidation and modifying agents in protein S-thiolation.

Glutathione is one of the most relevant antioxidants present in cells. It exerts its scavenging action through the involvement of efficient and ubiquitous enzymes. GSH on the other hand, because of its chemical features, can scavenge reactive oxygen species without the involvement of enzymatic systems. The study deals with the mobilization of GSH pool in a nonenzymatic antioxidant system by other physiological thiols (i.e., cysteine and cysteinyl-glycine), which are far more sensitive than GSH to oxidative conditions. These thiol compounds, in the presence of iron/EDTA, can promote oxygen activation through their oxidation to disulfides. GSH, through trans-thiolation reactions, can regenerate Cys and CysGly, which can then recycle, thus inducing a massive GSH oxidation. In these conditions, making use of bovine lens aldose reductase as a protein model, evidence is given that Cys and CysGly promote specific protein S-thiolation reactions. The possibility that GSH may be recruited in controlling cellular oxygen tension is considered.