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José Gómez

Publications and source records attributed to José Gómez.

6 recordsLinked to original sources
PubMed2006

Testing the vicious cycle theory of mitochondrial ROS production: effects of H2O2 and cumene hydroperoxide treatment on heart mitochondria.

Vicious cycle theories of aging and oxidative stress propose that ROS produced by the mitochondrial electron transport chain damage the mitochondria leading exponentially to more ROS production and mitochondrial damage. Although this theory is widely discussed in the field of research on aging and oxidative stress, there is little supporting data. Therefore, in order to help clarify to what extent the vicious cycle theory of aging is correct, we have exposed mitochondria in vitro to different concentrations of hydrogen peroxide or cumene-hydroperoxide (0, 30, 100 and 500 muM). We have found that 30 muM hydrogen peroxide (or higher concentrations) inhibit oxygen consumption in state 3 and increase ROS production with pyruvate/malate but not with succinate as substrate, indicating that these effects occur specifically at complex I. Similar levels of cumene-OOH inhibit state 3 respiration with both kinds of substrates, and increase ROS production in both state 4 and state 3 with pyruvate/malate and with succinate. The effects of cumene-OOH on ROS generation are due to action of the peroxide in the complex III or in the complex III plus complex I ROS generators. In all cases, the increase in ROS production occurred at a threshold level of peroxide exposure without further exponential increase in ROS generation. These results are consistent with the idea that ROS production can contribute to increase oxidative stress in old animals, but the results do not fit with a vicious cycle theory in which peroxide generation leads exponentially to more and more ROS production with age.

Animals↗
PubMed2006

Effect of graded corticosterone treatment on aging-related markers of oxidative stress in rat liver mitochondria.

Caloric restriction (CR) decreases aging rate and lowers the rate of reactive oxygen species (ROS) production at mitochondria in different organs, but the signal responsible for this last change is unknown. Glucocorticoids could constitute such a signal since it is well known that their levels increase during CR, and available studies failed to find consistent effects of insulin, the other better described hormone that varies during CR, on mitochondrial oxidative stress. In addition, there is almost no information on the possible in vivo effects of glucocorticoids on specific markers of mitochondrial and tissue oxidative stress. In this investigation, male Wistar rats were treated with corticosterone at doses of 150 and 400 mg/kg of diet during 4 weeks. After that time, oxidative stress-related parameters were measured in the liver. The corticosterone treatments did not change the rate of ROS production or the rate of oxygen consumption of rat liver mitochondria. The two lipoxidation protein markers measured (malondialdehyde-lysine and carboxymethyllysine) were decreased by both corticosterone treatments. These changes were associated with decreases in fatty acid unsaturation, especially with lowered levels of the highly unsaturated araquidonic and docosahexaenoic acids, which decrease the sensitivity to lipid peroxidation processes. The specific protein carbonyl glutamic semialdehyde, a marker of protein oxidation, was also lowered at 400 mg/kg corticosterone. The protein glycoxydation marker carboxyethyllysine and the level of oxidative damage to mtDNA (8-oxo-7,8-dihydro-2 9-deoxyguanosine) were increased by corticosterone. The results do not support the idea that corticosterone is the signal responsible for the decrease in mitochondrial ROS generation during CR. However, they show that this hormone modulates the level of oxidative stress both in proteins and in mtDNA. Some of these changes can contribute to the chronic effects of the hormone at tissue level.

Aging↗
PubMed2006

Calcium release domains in mammalian skeletal muscle studied with two-photon imaging and spot detection techniques.

The spatiotemporal characteristics of the Ca(2+) release process in mouse skeletal muscle were investigated in enzymatically dissociated fibers from flexor digitorum brevis (FDB) muscles, using a custom-made two-photon microscope with laser scanning imaging (TPLSM) and spot detection capabilities. A two-microelectrode configuration was used to electrically stimulate the muscle fibers, to record action potentials (APs), and to control their myoplasmic composition. We used 125 muM of the low-affinity Ca(2+) indicator Oregon green 488 BAPTA-5N (OGB-5N), and 5 or 10 mM of the Ca(2+) chelator EGTA (pCa 7) in order to arrest fiber contraction and to constrain changes in the [Ca(2+)] close to the release sites. Image and spot data showed that the resting distribution of OGB-5N fluorescence was homogeneous along the fiber, except for narrow peaks ( approximately 23% above the bulk fluorescence) centered at the Z-lines, as evidenced by their nonoverlapping localization with respect to di-8-ANEPPS staining of the transverse tubules (T-tubules). Using spot detection, localized Ca(2+) transients evoked by AP stimulation were recorded from adjacent longitudinal positions 100 nm apart. The largest and fastest DeltaF/F transients were detected at sites flanking the Z-lines and colocalized with T-tubules; the smallest and slowest were detected at the M-line, whereas transients at the Z-line showed intermediate features. Three-dimensional reconstructions demonstrate the creation of two AP-evoked Ca(2+) release domains per sarcomere, which flank the Z-line and colocalize with T-tubules. In the presence of 10 mM intracellular EGTA, these domains are formed in approximately 1.4 ms and dissipate within approximately 4 ms, after the peak of the AP. Their full-width at half-maximum (FWHM), measured at the time that Ca(2+) transients peaked at T-tubule locations, was 0.62 mum, similar to the 0.61 mum measured for di-8-ANEPPS profiles. Both these values exceed the limit of resolution of the optical system, but their similarity suggests that at high [EGTA] the Ca(2+) domains in adult mammalian muscle fibers are confined to Ca(2+) release sites located at the junctional sarcoplasmic reticulum (SR).

Animals↗
PubMed2005

Dietary restriction at old age lowers mitochondrial oxygen radical production and leak at complex I and oxidative DNA damage in rat brain.

Previous studies in mammalian models indicate that the rate of mitochondrial reactive oxygen species ROS production and the ensuing modification of mitochondrial DNA (mtDNA) link oxidative stress to aging rate. However, there is scarce information concerning this in relation to caloric restriction (CR) in the brain, an organ of maximum relevance for ageing. Furthermore, it has never been studied if CR started late in life can improve those oxidative stress-related parameters. In this investigation, rats were subjected during 1 year to 40% CR starting at 24 months of age. This protocol of CR significantly decreased the rate of mitochondrial H(2)O(2) production (by 24%) and oxidative damage to mtDNA (by 23%) in the brain below the level of both old and young ad libitum-fed animals. In agreement with the progressive character of aging, the rate of H(2)O(2) production of brain mitochondria stayed constant with age. Oxidative damage to nuclear DNA increased with age and this increase was fully reversed by CR to the level of the young controls. The decrease in ROS production induced by CR was localized at Complex I and occurred without changes in oxygen consumption. Instead, the efficiency of brain mitochondria to avoid electron leak to oxygen at Complex I was increased by CR. The mechanism involved in that increase in efficiency was related to the degree of electronic reduction of the Complex I generator. The results agree with the idea that CR decreases aging rate in part by lowering the rate of free radical generation of mitochondria in the brain.

Aging↗
PubMed2002

Effects of dual blockade of the renin-angiotensin system in primary proteinuric nephropathies.

BACKGROUND: Blockade of the renin-angiotensin system (RAS) with angiotensin converting enzyme (ACE) inhibitors or with angiotensin II type 1 (AT1) receptor blockers has been shown to reduce proteinuria and to slow down the progression of renal disease in diabetic and non-diabetic primary proteinuric nephropathies. Additionally, this beneficial effect is not dependent on blood pressure control. METHODS: To assess and compare the effects of lisinopril (up to 40 mg/day), candesartan (up to 32 mg/day) and combination therapy (lisinopril up to 20 mg/day plus candesartan up to 16 mg/day) on urinary protein excretion, 45 patients with primary proteinuric nephropathies (urinary protein/creatinine ratio 3.8+/-2.4 g/g) and normal or slightly reduced renal function (CCr 95+/-33 mL/min) were enrolled in a six month multicenter, prospective, open, randomized, active-controlled and parallel-group trial with 1:1:1 allocation. Blood pressure goal was set at or below 125/75 mm Hg for all patients, with additional antihypertensive medication prescribed if required. RESULTS: Renal function, estimated by creatinine clearance, remained stable throughout the study. Hyperkalemia (K>5.5 mmol/L) was detected in 3.1% of all measurements in follow-up, and was more frequent in patients treated with lisinopril alone or lisinopril plus candesartan (P<0.001) than in those on candesartan alone. No other relevant adverse event was recorded. The blood pressure goal (<125/75 mm Hg) was achieved by week 4 in all treatment groups (P<0.005 when compared to baseline), and afterwards the mean systolic and diastolic blood pressure remained below these values until the end of the trial with no statistically significant differences between groups. Urinary protein/creatinine ratio (percentage reduction 95% confidence intervals CI) decreased in patients treated with lisinopril alone to -33% (CI -12-56) to -31% (CI 0-68) and to -50% (CI -9-90), in patients treated with candesartan to -28% (CI -12-45), to -41% (CI -30-52) and to -48% (CI -32-63), in patients treated with the combination of both to -60% (CI -44-77) to -54% (CI -38-69) and to -70% (CI -57-83) at two, three, and six months, respectively. All comparisons with baseline achieved statistical significance and treatment with combination therapy was statistically more effective in proteinuria reduction than treatment with candesartan alone at two and six months (P=0.004 and P=0.023, respectively) and than treatment with lisinopril only at two months (P=0.03). CONCLUSION: Dual blockade of the renin-angiotensin system with ACE inhibitors and AT1 receptor blockers produces a beneficial antiproteinuric effect that could not be explained only by the systemic blood pressure reduction. All treatments were well tolerated.

Adult↗