Inflammation and oxidative stress markers in type 2 diabetes patients with Advanced Carotid atherosclerosis

BACKGROUND

Type 2 diabetes mellitus (T2DM) is a major global health issue and a significant risk factor for atherosclerosis. Atherosclerosis in T2DM patients has been associated with inflammation, insulin resistance, hyperglycemia, dyslipidemia, and oxidative stress. Identifying molecular features of atherosclerotic plaques in T2DM patients could provide valuable insights into the pathogenesis of the disease.

METHODS

The MASCADI (Arachidonic Acid Metabolism in Carotid Stenosis Plaque in Diabetic Patients) study aimed to investigate the increase of 2-arachidonoyl-lysophatidylcholine (2-AA-LPC) in carotid plaques from T2DM and control patients and to explore its association with plaque vulnerability as well as with blood and intra-plaque biomarkers altered during diabetes.

RESULTS

In a population of elderly, polymedicated patients with advanced stage of atherosclerosis, we found that T2DM patients had higher systemic inflammation markers, such as high-sensitivity C-reactive protein (hsCRP) and IL-1β, higher levels of oxysterols, increased triglyceride levels, and decreased HDL levels as compared to control patients. Furthermore, 2-AA-LPC was significantly enriched in plaques from diabetic patients, suggesting its potential role in diabetic atherosclerosis. Interestingly, 2-AA-LPC was not associated with systemic markers related to diabetes, such as hsCRP, triglycerides, or HDL cholesterol. However, it was significantly correlated with the levels of inflammatory markers within the plaques such as lysophospholipids and 25-hydroxycholesterol, strengthening the link between local inflammation, arachidonic acid metabolism and diabetes.

CONCLUSION

Our study is in line with a key role for inflammation in the pathogenesis of diabetic atherosclerosis and highlights the involvement of 2-AA-LPC. Further research is needed to better understand the local processes involved in the alteration of plaque composition in T2DM and to identify potential therapeutic targets.

TRIAL REGISTRATION

The MASCADI was registered on ClinicalTrials.gov (clinical registration number: NCT03202823).

Profiling of lipid mediators in atherosclerotic carotid plaques from type 2 diabetic and non-diabetic patients

BACKGROUND AND AIMS

Diabetes is associated with an accelerated development of atherosclerosis. Specific mechanisms related to diabetes and hyperglycemia may play a role in this process. In particular, alterations of arachidonic acid (AA) metabolism have been reported. Our main goal was to investigate for differences in the concentration of LTB4 and RvD1 as well as selected cyclooxygenase-derived mediators in carotid plaques from diabetic and non-diabetic patients. We also aimed to analyze the relationship between omega 6 and omega 3 Poly-Unsaturated Fatty acids (PUFAs) content in the plaques and the concentrations of these lipid mediators.

METHODS

29 type 2 diabetic patients and 30 control patients admitted for surgical treatment of carotid stenosis were enrolled in the present study. Carotid plaques were harvested for in-depth lipidomic profiling.

RESULTS

No differences for LTB4 or other lipid mediators were observed between diabetic and non-diabetic patients. RvD1 levels were below the threshold of quantification in most of the samples. A significant correlation was found between LTB4 and 5(S)-HETE levels. Omega 3 enrichment was not significantly different between control and diabetic plaques. There was a negative correlation between DHA/AA ratio and the level of 5(S)-HETE while there was a positive association with TXB2 and PGD2 concentrations.

CONCLUSION-PERSPECTIVES

Our results does not support the hypothesis of a specific involvement of LTB4 or COX-derived mediators in diabetic atherosclerosis. The relationship between DHA enrichment and the concentrations of specific inflammatory mediators within the plaque is of interest and will need to be confirmed in larger studies.

Comparison of two techniques (in vivo and ex-vivo) for evaluating the elastic properties of the ascending aorta: Prospective cohort study

Introduction

Aneurysms of the ascending aorta (AA) correspond to a dilatation of the ascending aorta that progressively evolves over several years. The main complication of aneurysms of the ascending aorta is type A aortic dissection, which is associated with very high rates of morbidity and mortality. Prophylactic ascending aorta replacement guidelines are currently based on maximal AA diameter. However, this criterion is imperfect. Stretching tests on the aorta carried out ex-vivo make it possible to determine the elastic properties of healthy and aneurysmal aortic fragments (tension test, resistance before rupture). For several years now, cardiac magnetic resonance imaging (MRI) has provided another means of evaluating the elastic properties of the aorta. This imaging technique has the advantage of being non-invasive and of establishing aortic compliance (local measurement of stiffness) without using contrast material by measuring the variation of the aortic surface area during the cardiac cycle, and pulse wave velocity (overall stiffness of the aorta).

Materials and methods

Prospective single-center study including 100 patients with ascending aortic aneurysm requiring surgery. We will perform preoperative cine-MRI and biomechanical laboratory stretching tests on aortic samples collected during the cardiac procedure. Images will be acquired with a 3T MRI with only four other acquisitions in addition to the conventional protocol. These additional sequences are a Fast Low Angle Shot (FLASH)-type sequence performed during a short breath-hold in the transverse plane at the level of the bifurcation of the pulmonary artery, and phase-contrast sequences that encodes velocity at the same localization, and also in planes perpendicular to the aorta at the levels of the sino-tubular junction and the diaphragm for the descending aorta. For ex-vivo tests, the experiments will be carried out by a biaxial tensile test machine (ElectroForce®). Each specimen will be stretched with 10 times of 10% preconditioning and at a rate of 10 mm/min until rupture. During the experiment, the tissue is treated under a 37°C saline bath. The maximum elastic modulus from each sample will be calculated.

Results

The aim of this study is to obtain local patient-specific elastic modulus distribution of the ascending aorta from biaxial tensile tests and to assess elastic properties of the aorta using MRI, then to evaluate the correlation between biaxial tests and MRI measurements.

Discussion

Our research hypothesis is that there is a correlation between the evaluation of the elastic properties of the aorta from cardiac MRI and from stretching tests performed ex-vivo on aorta samples collected during ascending aorta replacement.

Aortic root remodeling with external annuloplasty for acute type A aortic dissection: Midterm results

BACKGROUND

To evaluate the role of aortic root remodeling with external aortic annuloplasty (ARREAA) in acute type A aortic dissection (AAAD).

METHODS

From May 2011 to May 2020, 59 patients out of 240 with AAAD underwent ARREAA. Data were retrospectively collected and analyzed.

RESULTS

The mean age was 61.4 ± 8.6 years and 43 patients were males (73%). Hemiarch and total arch replacement were performed in 37 (62.7%) and 14 (23.7%) patients. An aortic valvuloplasty was performed in seven patients (11.8%). Five patients (8.5%) required coronary artery bypass graft. Re-exploration for bleeding was required in six patients (10.1%). The 30-day mortality rate was 18.6%. Preoperative hemodynamic instability (odds ratio [OR] = 8.57, 95% confidence interval [CI] = 1.57-46.71; p = 0.013), consciousness disorder (OR = 19.18, 95% CI = 3.02-121.72]; p = 0.002) or myocardial ischemia (OR = 6.28, 95% CI = 1.27-31.10; p = 0.013) were significantly associated with postoperative mortality. No patient was reoperated for aortic valve during the postoperative period. One patient suffered a stroke postoperatively with partial recovery. Kidney failure requiring temporary dialysis occurred in 12 patients (20.3%). At discharge, a transthoracic echocardiogram showed moderate aortic regurgitation (AR; grade 2) in two patients. During follow-up (mean = 58.4 ± 32.4 months), three patients died. The rate of mortality was 6.2%. Actuarial survival at 5 years was 76.3%. No patient required reoperation on the proximal aorta or aortic valve. At 4 years, freedom from any aortic valve or root reintervention and AR > 2 were both 100%.

CONCLUSION

In a center with expertise in valve-sparing procedures, ARREAA is a reasonable option in the surgical management of AAAD in selected patients. This technique stabilizes the aortic annulus and preserves root anatomy for durable outcomes.

Multiplexed flow cytometric analyses of pro- and anti-inflammatory cytokines in the culture media of oxysterol-treated human monocytic cells and in the sera of atherosclerotic patients

BACKGROUND

Some oxysterols are identified in atheromatous plaques and in plasma of atherosclerotic patients. We asked whether they might modulate cytokine secretion on human monocytic cells. In healthy and atherosclerotic subjects, we also investigated the relationships between circulating levels of C-reactive protein (CRP), conventional markers of hyperlipidemia, some oxysterols (7beta-hydroxycholesterol, 7-ketocholesterol, and 25-hydroxycholesterol), and various cytokines.

METHODS

Different flow cytometric bead-based assays were used to quantify some cytokines (IL-1beta, IL-2, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12, IL-13, IL-17, G-CSF, GM-CSF, IFN-gamma, MCP-1, MIP-1beta, or TNF-alpha) in the culture media of oxysterol-treated U937 and THP-1 cells, and in the sera of healthy and atherosclerotic subjects. CRP and markers of hyperlipidemia were determined with routine analytical methods. Oxysterols were quantified by gas chromatography/mass spectrometry. Flow cytometric and biochemical methods were used to measure IL-8 mRNA levels, intracellular IL-8 content, and protein phosphorylation in the mitogenic extracellular kinase/extracellular signal-regulated kinase1/2 (MEK/ERK1/2) signaling pathway.

RESULTS

All oxysterols investigated are potent in vitro inducers of MCP-1, MIP-1beta, TNF-alpha, and/or IL-8 secretion, the latter involving the MEK/ERK1/2 cell signaling pathway. In healthy and atherosclerotic subjects, no relationships were found between cytokines (IL-8, IL-1beta, IL-6, IL-10, TNF-alpha, IL-12, and MCP-1), CRP, conventional markers of hyperlipidemia, and oxysterols. However, in patients with arterial disorders of the lower limbs, small but statistically significant differences in the circulating levels of CRP, TNF-alpha, and IL-10 were observed comparatively to healthy subjects and according to the atherosclerotic stage considered.

CONCLUSIONS

Flow cytometric bead-based assays are well adapted to measure variations of cytokine secretion in the culture media of oxysterol-treated cells and in the sera of healthy and atherosclerotic subjects. They underline the in vitro proinflammatory properties of oxysterols and may permit to distinguish healthy and atherosclerotic subjects, as well as various atherosclerotic stages.

Involvement of a calcium-dependent dephosphorylation of BAD associated with the localization of Trpc-1 within lipid rafts in 7-ketocholesterol-induced THP-1 cell apoptosis

7-Ketocholesterol is a component of oxidized LDL, which plays a central role in atherosclerosis. It is a potent inducer of cell death towards a wide number of cells involved in atherosclerosis. In this study, it is reported that 7-ketocholesterol treatment induces an increase of cytosolic-free Ca(2+) in THP-1 monocytic cells. This increase is correlated with the induction of cytotoxicity as suggested from experiments using the Ca(2+) channel blockers verapamil and nifedipine. This 7-ketocholesterol-induced apoptosis appears to be associated with the dephosphorylation of serine 75 and serine 99 of the proapoptotic protein Bcl-2 antagonist of cell death (BAD). We demonstrated that this dephosphorylation results mainly from the activation of calcium-dependent phosphatase calcineurin by the oxysterol-induced increase in Ca(2+). Moreover, this Ca(2+) increase appears related to the incorporation of 7-ketocholesterol into lipid raft domains of the plasma membrane, followed by the translocation of transient receptor potential calcium channel 1, a component of the store operated Ca(2+) entry channel, to rafts.

Impairment of the cytotoxic and oxidative activities of 7 beta-hydroxycholesterol and 7-ketocholesterol by esterification with oleate

Atherosclerosis involves inflammatory processes, as well as cytotoxic and oxidative reactions. In atherosclerotic plaques, these phenomena are revealed by the presence of dead cells, oxidized lipids, and oxidative DNA damage, but the molecules triggering these events are still unknown. As 7 beta-hydroxycholesterol and 7-ketocholesterol, which are present at elevated concentrations in atherosclerotic lesions, are strongly cytotoxic and pro-oxidative, their effects were determined on cell death, superoxide anion and nitric oxide production, lipid peroxidation, and oxidative DNA damage. 7-Ketocholesterol- and 7 beta-hydroxycholesterol-induced cell death leads to a loss of mitochondrial potential, to increased permeability to propidium iodide, and to morphological nuclear changes (swelling, fragmentation, and/or condensation of nuclei). These effects are preceded by the formation of cytoplasmic monodansylcadaverine-positive structures and are associated with a rapid enhancement of cells overproducing superoxide anions, a decrease in cells producing nitric oxide, lipid peroxidation (formation of malondialdehyde and 4-hydroxynonenal adducts, low ratio of [unsaturated fatty acids]/[saturated fatty acids]) as well as oxidative DNA damage (8-oxoguanine formation). Noteworthy, none of the cytotoxic features previously observed with 7 beta-hydroxycholesterol and 7-ketocholesterol were noted with cholesterol, 7 beta-hydroxycholesteryl-3-oleate and 7-ketocholesteryl-3-oleate, with the exception of a slight increase in superoxide anion production with 7 beta-hydroxycholesteryl-3-oleate. This finding supports the theory that 7 beta-hydroxycholesterol and 7-ketocholesterol could induce cytotoxic and oxidative processes observed in atherosclerotic lesions and that esterification of these compounds may contribute to reducing atherosclerosis progression.

Influence of deep hypothermia on the tolerance of the isolated cardiomyocyte to ischemia-reperfusion

The influence of deep hypothermia (4 degrees C) during a substrate-free, hypoxia-reoxygenation treatment was investigated on cardiomyocytes (CM) prepared from newborn rat heart in culture in an in vitro, substrate-free model of ischemia-reperfusion. The transmembranous potentials were recorded with standard microelectrodes. The contractions were monitored photometrically. The RNA messenger (mRNA) and protein expression for protein (HSP70) were analysed by RT-PCR (reverse transcriptase-polymerase chain reaction) and Western blotting, respectively. Simulated ischemia (SI) caused a gradual decrease and then a cessation of the spontaneous electromechanical activity. During the reoxygenation, the CM recovered normal function, provided that SI did not exceed 2.5 h. When SI duration was increased up to 4 h, reoxygenation failed to restore the spontaneous electromechanical activity. Conversely, the exposure of the CM to SI together with deep hypothermia decreased the functional alterations observed, and provided a complete electromechanical recovery after 2.5 h as well as after 4 h of SI. Deep hypothermia alone failed to induce HSP70 mRNA and protein production. On the contrary, HSP70 mRNA production increased after 2.5 and 4 h of deep hypothermia followed by 1 h of rewarming, proportionally to the duration of the cooling period. This augmentation in mRNA was associated with a rise in HSP70 protein content. In summary, it appeared that deep hypothermia exerts a strong cytoprotective action during SI only, whereas cooling CM before SI has no beneficial effect on subsequent SI. Moreover, these results suggested the persistence of a signaling system and/or transduction in deeply cooled, functionally depressed cells. Finally, CM in culture appeared to be a model of interest for studying heart graft protection against ischemia-reperfusion and contributed to clarifying the molecular and cellular mechanisms of deep hypothermia on myocardium.

Postischemic myocardial recovery and oxidative stress status of vitamin C deficient rat hearts

OBJECTIVE

To investigate the role of vitamin C tissue content as a protective agent during myocardial ischemia-reperfusion injury, we have evaluated the postischemic functional recovery and free radical release of osteogenic disorder Shionogi (ODS) inherently scorbutic rat hearts and compared them to healthy Wistar rat hearts.

METHODS

Isolated perfused hearts of ODS or Wistar rats underwent 30 min of a global total normothermic ischemia followed by 30 min of reperfusion. The lipid-soluble spin trap alpha-phenyl N-tert-butylnitrone (3 mM) was perfused upstream of the coronary bed. Functional parameters were recorded and samples of coronary effluents were analysed using electron spin resonance spectroscopy to characterise and quantify the amount of radical species released.

RESULTS

From the onset of reperfusion, a large and long-lasting release of alkyl/alkoxyl radicals was detected, with a peak value of 29.0+/-3.2 nM obtained after 13 min, which was associated with a persistent contractile dysfunction. However, ODS rat hearts showed a higher myocardial recovery with lower left ventricular end diastolic pressure (44.34+/-1.74 vs. 55.03+/-1.57 mmHg for Wistar), higher recovery of rate pressure product (12.3+/-1.4 vs. 1.9+/-1.7x10(3) mmHg beats/min for Wistar) and shorter duration of contractile abnormalities during reperfusion (3.7+/-1.0 vs. 20.8+/-5.3 min for Wistar). Moreover, free radical release was identical in ODS rat hearts as compared to control Wistar rats. Ascorbic acid tissue content was significantly altered in ODS rats (31.9+/-3.3 vs. 591.0+/-54.9 mmol/g of tissue for Wistar) but superoxide dismutases, glutathion peroxidases and inducible heat shock protein 70 genes were up-regulated.

CONCLUSIONS

This study shows that ascorbic-acid-deficient ODS rat hearts are more resistant to an ischemic insult than control Wistar rats, probably through the development of alternative protective defences, like the induction of heat shock proteins. These paradoxical results raise the question of the relative importance of each endogenous antioxidant in the cardiac resistance to ischemia-reperfusion injury.

Upregulation of the Netrin Receptor (DCC) Gene during Activation of B Lymphocytes and Modulation by Interleukins

The DCC (deleted in colon cancer) gene has a brain restricted high expression pattern. It encodes a transmembrane protein of the immunoglobulin superfamily identified as the netrin-1 receptor. It might be a member of the so called "brain-lymphoid" molecules, which control key cell surface events. To test this hypothesis we have assessed the DCC mRNA level in human normal and malignant myeloid and lymphoid cells. A high mRNA content has been observed only in mature B cells at the secreting or presecreting stage. Expression of DCC was also assessed in the anti-CD40 model of immunopoiesis. Activation of purified tonsillar B cells by anti-CD 40 antibody strongly increased the DCC mRNA level and this effect was dramatically enhanced by the association of IL-2 + IL-10, which is a potent and selective in vitro inducer of the B cell memory phenotype. In contrast no effect has been detected after activation of T cells by anti-CD3. These data suggest that the DCC encoded netrin receptor is involved in B cell immunopoiesis.

Role of nitric oxide synthases in the infarct size-reducing effect conferred by heat stress in isolated rat hearts

Nitric oxide (NO) donors are known to induce both delayed cardioprotection and myocardial heat stress protein (HSP) expression. Moreover, heat stress (HS), which also protects myocardium against ischaemic damages, is associated with a NO release. Therefore, we have investigated the implication of NO in HS-induced resistance to myocardial infarction, in the isolated rat heart model. Rats were divided in six groups (n=10 in each group), subjected or not to heat stress (42 degrees C internal temperature, 15 min) and treated or not with nitro-L-arginine-methylester (L-NAME) a non-selective inhibitor of NO synthase isoforms, or L-N(6)-(1-imino-ethyl)lysine (L-NIL), a selective inhibitor of the inducible NO synthase. Twenty-four hours after heat stress, their hearts were isolated, retrogradely perfused, and subjected to a 30-min occlusion of the left coronary artery followed by 120 min of reperfusion. Infarct-to-risk ratio was significantly reduced in HS (18.7+/-1.6%) compared to Sham (33.0+/-1.7%) hearts. This effect was abolished in L-NAME-treated (41.7+/-3.1% in HS+L-NAME vs 35.2+/-3.0% in Sham+L-NAME ) and L-NIL-treated (36.1+/-3.4% in HS+L-NIL vs 42.1+/-4.6% in Sham+L-NIL) groups. Immunohistochemical analysis of myocardial HSP 27 and 72 showed an HS-induced increase of these proteins, which was not modified by L-NAME pretreatment. We conclude that NO synthases, and in particular the inducible isoform, appear to play a role in the heat stress-induced cardioprotection, independently of HSP 27 and 72 levels. Further investigations are required to elucidate the precise role of HSPs in this adaptive response.

Changes in HSP70 and P53 expression are related to the pattern of electromechanical alterations in rat cardiomyocytes during simulated ischemia

The objective was to relate the response of the HSP70 and P53 genes to the cessation and the recovery of cardiac muscle cell functions when submitted to ischemia-reperfusion. We have measured the electromechanical activity, the released enzymes and HSP70 RNA and protein levels in cultured neonatal rat cardiomyocytes (CM) in a substrate-free, hypoxia-reoxygenation model of ischemia-reperfusion. In parallel the expression of the two genes P53 (the key apoptosis regulator gene) and P21/Waf1 (the P53 target gene) has been evaluated. The functional recovery during post-'ischemic' reoxygenation was associated with an overexpression of HSP70 and P53 lasting until the functional parameters reverted back to the normal, prehypoxic values. In contrast, extending the substrate-free hypoxic treatment worsens the dysfunction of the cardiac muscle cell and, in these conditions, reoxygenation failed to restore cell functions and to activate HSP70. Finally, in the conditions of reversible 'ischemic' cell injury, an early and transitory activation of P53 was associated with the functional recovering process of the CM submitted to simulated ischemia. These observations are suggestive of a contributive role of both HSP70 and P53 to a cytoprotective program activated by reoxygenation in post-'ischemic' CM.

Levels of nitric oxide in the heart after experimental myocardial ischemia

The effect of myocardial ischemia on nitric oxide (NO) production is controversial in part because of indirect NO quantification. In the present study, direct quantification of NO was investigated in an in vivo rat model of myocardial ischemia (MI). A NO spin-trapping technique using electron spin resonance (ESR) spectroscopy was used to study NO production in the ischemic and in the nonischemic area of the rat heart 2, 8, or 24 h after left main coronary artery ligation. The method was based on the trapping of NO by a metal-chelator complex consisting of N-methyl-D-glucamine-dithiocarbamate (MGD) and Fe(II) to form a stable NO-FeMGD complex that gives rise to a characteristic triplet ESR spectrum. This metal-chelator complex was administered half an hour before sacrifice of the rats. A large and time-dependent increase of the ESR signal corresponding to the NO-FeMGD complex was observed 8 h (11.6 +/- 0.9 arbitrary units [AU]) and 24 h (29.7 +/- 2.9 AU) in the ischemic area after MI. On the contrary, no ESR triplet was observed in the nonischemic region of the heart and in sham-operated rats. NO blood derivative levels (nitrosylhemoglobin and plasma nitrites and nitrates) were unchanged compared with sham-operated rats. Previous administration of aminoguanidine, a NO synthase inhibitor, in animals subjected to a 24-h ischemia resulted in a complete abolition in the NO-FeMGD spectrum in the ischemic area. These findings directly demonstrated an increase of the NO-FeMGD levels during in vivo myocardial ischemia that appeared to be specifically localized in the ischemic area.

Ceramide generation occurring during 7beta-hydroxycholesterol- and 7-ketocholesterol-induced apoptosis is caspase independent and is not required to trigger cell death

Biological activities of oxysterols seem tightly regulated. Therefore, the ability to induce cell death of structurally related oxysterols, such as those oxidized at C7(7alpha-, 7beta-hydroxycholesterol, and 7-ketocholesterol), was investigated on U937 cells at different times of treatment in a concentration range of 5-80 microg/ml. Whereas all oxysterols accumulate inside the cells, strong inhibition of cell growth and increased permeability to propidium iodide were observed only with 7beta-hydroxycholesterol and 7-ketocholesterol, which trigger an apoptotic process characterized by the occurrence of cells with fragmented and/or condensed nuclei, and by various cellular dysfunctions: loss of mitochondrial transmembrane potential, cytosolic release of cytochrome c, activation of caspase-9 and -3 with subsequent enhanced activity of caspase-3, degradation of poly(ADP-ribose) polymerase, and increased accumulation of cellular C16 : 0 and C24 : 1 ceramide species. This ceramide generation is not attributed to caspase activation since inhibition of 7beta-hydroxycholesterol- and 7-ketocholesterol-induced apoptosis by Z-VAD-fmk (100 microM), a broad spectrum caspase inhibitor, did not reduce C16 : 0 and C24 : 1 ceramide species accumulation. Conversely, when U937 cells were treated with 7beta-hydroxycholesterol and 7-ketocholesterol in the presence of fumonisin B1 (100 microM), a specific inhibitor of ceramide synthase, C16 : 0 and C24 : 1 ceramide species production was completely abrogated whereas apoptosis was not prevented. Noteworthy, 7alpha-hydroxycholesterol induced only a slight inhibition of cell growth. Collectively, these results are consistent with the notion that the alpha or beta hydroxyl radical position of oxysterols oxidized at C7 plays a key role in the induction of the apoptotic process. In addition, our findings demonstrate that 7beta-hydroxycholesterol- and 7-ketocholesterol-induced apoptosis involve the mitochondrial signal transduction pathway and they suggest that C16 : 0 and C24 : 1 ceramide species generated through ceramide synthase play a minor role in the commitment of 7beta-hydroxycholesterol- and 7-ketocholesterol-induced cell death.

The detection of tyrosinase mRNA in the peripheral blood of stage I melanoma patients is not of clinical relevance in predicting metastasis risk and survival

The presence of tyrosinase mRNA in the peripheral blood cells of melanoma patients has been recently studied as a possible marker of haematogenous dissemination. However, considerable variations in the rates of detection have been noted. We determined the presence of tyrosinase mRNA-positive circulating cells using reverse transcriptase-polymerase chain reaction (RT-PCR) in 35 patients with stage I melanoma, two patients with stage II melanoma and two patients with stage III melanoma. Among the patients with stage 1, 13 were tested before and after surgery (< 1 h). Twenty healthy subjects served as negative controls. Out of the melanoma patients, the tyrosinase gene was expressed in three of the 52 samples tested. Tyrosinase mRNA was present in the circulating cells of only one patient with stage I melanoma after intra-congenital naevi resection. However, two other stage I patients developed rapidly lethal metastasis within the following 6 months, despite the lack of detectable tyrosinase mRNA. None of stage II patients were positive for the tyrosinase transcripts, while both patients with stage III melanoma showed enzyme expression. Our results confirm those of previous studies, showing that a small proportion of stage I melanoma patients have tyrosinase-positive circulating cells. Moreover, the lack of tyrosinase mRNA detection in the blood does not necessarily exclude metastatic progression. Therefore, this study indicates that the detection of tyrosinase mRNA-positive circulating cells by RT-PCR is not a predictive biomarker of a metastasis risk in patients with stage I melanoma.

Antioxidative properties of pyruvate and protection of the ischemic rat heart during cardioplegia

Formation of oxygen free radicals during heart transplantation seems to be related to the alterations occurring during ischemia and reperfusion and could explain the short preservation time of donor hearts. The aim of our study was (a) to analyze the protective effects of pyruvate during cold cardioplegia and ischemia/reperfusion sequence, and (b) to investigate in vitro the radical scavenging properties of this compound. After 30 min of perfusion, isolated working rat hearts were arrested by cardioplegic solution, stored 4 h in B21 solutions at 4 degrees C, and reperfused with Krebs-Henseleit buffer for 45 min. Pyruvate (2 mM) was added to Krebs-Henseleit, cardioplegic, and storage solutions, and functional parameters were recorded throughout the experiments. In a second part, control hearts and hearts treated with pyruvate were cannulated via the aorta and perfused for 30 min by the Langendorff method, arrested by cardioplegic solution, stored 4 h in B21 solutions at 4 degrees C, and reperfused for 45 min by the Langendorff method. Malonedialdehyde and alpha-tocopherol levels were determined on heart homogenate. In situ detection of apoptotic cells also was performed on tissue samples (left ventricle) at the end of the ischemia/reperfusion sequence. To demonstrate in vitro the antioxidant effects of pyruvate, we monitored (a) its hydroxyl radical scavenging properties by using electron paramagnetic resonance (EPR) spectroscopy, and (b) the decrease of fluorescence of allophycocyanin, in the presence of a Fenton system (H2O2/Cu2+). Ischemia for 4 h, followed by myocardial reperfusion, resulted in substantially reduced mechanical function. Hearts subjected to this ischemia and pretreated with pyruvate showed a significant improvement in the function recovery. After the ischemia/reperfusion protocol, no significant decrease of malonedialdehyde levels was shown on hearts treated with pyruvate. However, alpha-tocopherol levels were higher in the pyruvate group compared with the control group. At the end of the reperfusion period, levels of apoptotic cells were significantly lower in hearts treated with pyruvate compared with control hearts. EPR studies showed that pyruvate was an efficient hydroxyl scavenger, with a median inhibitory concentration (IC50) of 8 mM. The allophycocyanin assay also showed a dose-dependent effect of pyruvate against hydroxyl radicals. In conclusion, these findings showed that pyruvate could prevent reperfusion injuries in the isolated heart, probably by its antioxidative properties. The application of pyruvate may contribute to the preservation of hearts for organ transplantation.

Pattern of superoxide dismutase enzymatic activity and RNA changes in rat heart ventricles after myocardial infarction

A multiplex reverse transcription polymerase chain reaction assay was designed to measure manganese superoxide dismutase (MnSOD) and CuZnSOD mRNAs in the left and right ventricles of rat hearts after myocardial infarction induced by occlusion of the left coronary artery. These data were compared with changes in enzymatic activities. In the left ventricle, Mn-SOD RNA increased significantly at 6 hours, peaked at 12 hours (490 +/- 38 arbitrary units), and progressively decreased (127 +/- 21 arbitrary units at 48 hours). In contrast, there was a steady accumulation of transcripts in the right ventricle up to 48 hours. In both ventricles, the changes in the MnSOD mRNA and protein content were not associated with proportional variations in enzymatic activity. There was no characteristic alteration of the CuZnSOD system in either ventricle over the 48-hour period. These results demonstrate that infarction selectively activates the MnSOD gene in the viable myocardium of both ventricles. They suggest that MnSOD may be involved in the adaptive response of myocytes to the overloading stress.