Myocardial ischemia-reperfusion damage after pacing-induced tachycardia in patients with cardiac syndrome X

The presence of myocardial ischemia in syndrome X (chest pain, "ischemia-like" electrocardiogram changes, and normal coronary angiograms) is uncertain possibly because, when focally distributed, it may not cause contractile dysfunction or lactate production. We measured lipid hydroperoxides (ROOHs) and conjugated dienes (CDs), two sensitive, independent markers of ischemia-reperfusion oxidative stress, in paired aortic and great cardiac vein blood samples before and after pacing-induced tachycardia in nine patients with syndrome X. Diagnostic ischemic S-T segment changes during pacing were followed by a consistent increase in ROOH and CD levels in the great cardiac vein (from 4.83 +/- 1.18 micromol/l at baseline to 7.88 +/- 1.12 micromol/l and from 0.038 +/- 0.002 to 0.051 +/- 0.003 arbitrary units, respectively, P < 0.01). In controls, ROOH and CD levels did not change after pacing. The large postpacing cardiac release of lipid peroxidation products, consistently observed in all patients and similar to that previously observed after ischemia caused by percutaneous transluminal coronary angioplasty, is consistent with an ischemic origin of syndrome X.     

Hydrogen peroxide-induced base damage in deoxyribonucleic acid

Aqueous solutions of calf thymus deoxyribonucleic acid (DNA) were exposed to hydrogen peroxide in the presence of air. Base products formed in DNA were identified and quantitated following acid hydrolysis and trimethylsilylation using gas chromatography-mass spectrometry. The yields of these products were dependent upon the hydrogen peroxide concentration, and increased in the following order: 8-hydroxyadenine, cytosine glycol, 2,6-diamino-4-hydroxy-5-formamidopyrimidine, 8-hydroxyguanine, thymine glycol, and 4,6-diamino-5-formamidopyrimidine. Previous studies have shown that these compounds are typically formed in DNA in aqueous solution by hydroxyl radicals generated by ionizing radiation. Hydrogen peroxide is thought to participate in a Fenton-like reaction with transition metals, which are readily bound to DNA in trace quantities, resulting in the production of hydroxyl radicals close to the DNA. This proposed mechanism was examined by exposing DNA to hydrogen peroxide either in the presence of a hydroxyl radical scavenger or following pretreatment of DNA with metal-ion chelators. The results indicate that trace quantities of transition metal ions can react readily with hydrogen peroxide to produce radical species. The production of radical species was monitored by determining the altered bases that resulted from the reaction between radicals and DNA. The yields of the base products were reduced by 40 to 60% with 10 mmol dm-3 of dimethyl sulfoxide. A 100-fold increase in the concentration of dimethyl sulfoxide did not result in a further reduction in hydrogen peroxide-induced base damage. DNA which was freed from bound metal ions by pretreatment with metal ion chelators followed by exhaustive dialysis was found to be an ineffective substrate for hydrogen peroxide. The yields of base products measured in this DNA were at background levels. These results support the role of metal ions bound to DNA in the site-specific formation of highly reactive radical species, most likely hydroxyl radicals, in hydrogen peroxide-induced damage to the bases in DNA.     

Elevated circulating inflammatory markers in female patients with cardiac syndrome X

Background. The pathophysiological mechanism in cardiac syndrome X has been suggested as impairment in normal endothelial function of the coronary microvasculature, resulting in inadequate flow reserve. However, despite the extensive studies, the precise mechanisms in cardiac syndrome X remain unclear. Purpose. The present study was, therefore, to investigate whether inflammatory cells and markers such as C-reactive protein (CRP) and interleukin-6 (IL-6) might be involved in the pathogenesis of cardiac syndrome X. Methods. Thirty-six female patients with cardiac syndrome X and 30 sex-matched normal controls were prospectively enrolled in this study. Blood samples were drawn for measuring white blood and monocyte cells, inflammatory markers such as CRP and IL-6, and data were compared between patients with cardiac syndrome X and normal controls. Results. The data showed that increased numbers of white blood and monocyte cells were found in patients with cardiac syndrome X compared with normal controls (white blood cells: 7072 ± 1146/mm³ vs. 6138 ± 1079/mm³; monocyte cells: 612 ± 186/mm³ vs. 539 ± 190/mm³ p < 0.05, respectively). Moreover, patients with cardiac syndrome X were detected to have significantly higher plasma CRP and IL-6 levels in comparison with patients with normal controls (CRP: 0.48 ± 0.26 mg/L vs. 0.22 ± 0.15 mg/L; IL-6: 13.4 ± 1.2 pg/dl vs. 6.2 ± 0.6 pg/dl, p < 0.01, respectively). The multivariate analysis showed that CRP was the independent variable most strongly associated with cardiac syndrome X. Conclusions. Our data suggested that low-grade, chronic inflammation might contribute to the development of cardiac syndrome X manifested by increased plasma levels of inflammatory cells and inflammatory markers.     

Elevated circulating inflammatory markers in female patients with cardiac syndrome X

Background. The pathophysiological mechanism in cardiac syndrome X has been suggested as impairment in normal endothelial function of the coronary microvasculature, resulting in inadequate flow reserve. However, despite the extensive studies, the precise mechanisms in cardiac syndrome X remain unclear. Purpose. The present study was, therefore, to investigate whether inflammatory cells and markers such as C-reactive protein (CRP) and interleukin-6 (IL-6) might be involved in the pathogenesis of cardiac syndrome X. Methods. Thirty-six female patients with cardiac syndrome X and 30 sex-matched normal controls were prospectively enrolled in this study. Blood samples were drawn for measuring white blood and monocyte cells, inflammatory markers such as CRP and IL-6, and data were compared between patients with cardiac syndrome X and normal controls. Results. The data showed that increased numbers of white blood and monocyte cells were found in patients with cardiac syndrome X compared with normal controls (white blood cells: 7072 ± 1146/mm³ vs. 6138 ± 1079/mm³; monocyte cells: 612 ± 186/mm³ vs. 539 ± 190/mm³ p < 0.05, respectively). Moreover, patients with cardiac syndrome X were detected to have significantly higher plasma CRP and IL-6 levels in comparison with patients with normal controls (CRP: 0.48 ± 0.26 mg/L vs. 0.22 ± 0.15 mg/L; IL-6: 13.4 ± 1.2 pg/dl vs. 6.2 ± 0.6 pg/dl, p < 0.01, respectively). The multivariate analysis showed that CRP was the independent variable most strongly associated with cardiac syndrome X. Conclusions. Our data suggested that low-grade, chronic inflammation might contribute to the development of cardiac syndrome X manifested by increased plasma levels of inflammatory cells and inflammatory markers.     

Long-term prognosis of patients with cardiac syndrome X: a review

AimsFollow-up studies of patients with cardiac syndrome X (CSX) generally report good prognosis. However, some recent studies report an adverse outcome for women.ConclusionThe present review of recent archival literature demonstrates an overall major cardiac event rate of 1.5% per 5 years. Although this is an excellent prognosis for CSX patients, the quality of life is impaired because of the high recurrence rate of angina pectoris (55%).     

Increased DNA damage in patients with complete hydatidiform mole

The pathologic mechanisms underlying the gestational trophoblastic diseases are largely unexplored, but are thought to involve oxidative damage to the maternal vasculature and also to the placenta. In this study we have assessed the plasma levels of total antioxidant response (TAR) and the levels of endogenous DNA damage--determined by the comet assay--in peripheral blood lymphocytes from 13 women with complete hydatidiform mole (CHM) and compared these with those of 12 healthy pregnant controls and 10 healthy non-pregnant controls. Significantly lower mean levels of plasma TAR were found in patients with CHM compared with healthy pregnant controls (1.08+/-0.29 versus 1.17+/-0.14 mmol Trolox Eq/L, p<0.05) and with healthy non-pregnant controls (1.08+/-0.29 versus 1.38+/-0.12 mmol Trolox Eq/L, p<0.05). Significantly higher mean levels of endogenous DNA damage were observed in patients with CHM than in healthy pregnant controls (234.5+/-50.74 versus 125.7+/-45.4 AU, p<0.05) or in healthy non-pregnant controls (234.5+/-50.74 versus 104.0+/-49.6 AU, p<0.05). We observed an inverse correlation between the plasma TAR and the levels of endogenous DNA damage (r=-0.64, p<0.01), in that the levels of oxidative damage to the DNA were found to parallel the decrease in the plasma TAR in the CHM group. These results reveal a relationship between the extracellular and intracellular (as reflected by damage to the DNA) levels of oxidation. Our observations suggest that there is a link between the increased levels of oxidative stress and the increase in endogenous DNA damage seen in patients with CHM, as compared with those seen in normal pregnancy. However, the nature of this link, and whether it is direct or indirect, remains to be explored.     

Circulating mononuclear superoxide production and inflammatory markers for long-term prognosis in patients with cardiac syndrome X

Increased oxidative stress and vascular inflammation have been shown in patients with cardiac syndrome X (CSX; angina, exercise-induced ischemia, and normal coronary angiogram). This study was conducted to assess the impact of basal superoxide generation by circulating mononuclear cells (MNCs), a contributor to intravascular oxidative stress, and serum inflammatory biomarkers, including high-sensitivity C-reactive protein, homocysteine, soluble intercellular adhesion molecule-1, soluble vascular adhesion molecule-1, and von Willebrand factor, on the long-term prognosis of CSX. During a mean follow-up of 31.5 +/- 14.2 months (maximum 5 years), a total of 12 events were recorded in 92 consecutive CSX patients. There were no deaths or myocardial infarctions, but 8 hospitalizations for acute coronary syndrome, 3 for stroke, and 1 for congestive heart failure due to left ventricular systolic dysfunction. Under univariate analysis, only basal superoxide generation by MNCs was associated with the risk for cardiovascular event. Based on multivariate analysis, basal superoxide generation by MNCs could still independently predict future events (relative risk for the highest compared to the lowest tertile, 3.87; 95% confidence interval, 1.42-10.54, p = 0.008). These findings demonstrate that long-term prognosis is fair in patients with CSX. Basal superoxide production of MNCs independently predicts future cardiovascular events, suggesting its potential role in measuring disease progression and risk stratification in these patients.     

X chromosome-inactivation patterns in patients with Rett syndrome

Rett syndrome (RS) is a complex and severely disabling neurologic disorder, restricted to females. As non-random X inactivation could indicate that the X chromosome has a role in the etiology of the syndrome, we performed molecular analysis based on the differential methylation of the active and inactive X chromosomes with probe M27β, taking into account the parental origin of the two Xs, in 24 RS girls (including a pair of concordant monozygote twins), 22 mothers, and a control group of 30 normal women. The results showed a significantly (Fisher’s exact test) increased frequency of skewed X inactivation in lymphocytes from 15/23 RS compared with 4/22 mothers (P = 0.0031) and 6/30 controls (P = 0.0021). Our results, together with those from the literature, showed that as a group, RS patients are apparently more prone to skewed X inactivation than their mothers and normal controls, and this suggests that the X chromosome is somehow involved in RS etiology. Received: 13 February 1997 / Accepted: 5 November 1997     

Depurination-induced infidelity of deoxyribonucleic acid synthesis with purified deoxyribonucleic acid replication proteins in vitro

Removal of purine bases from phi X174 single-stranded DNA leads to increased reversion frequency of amber mutations when this DNA is copied in vitro with purified DNA polymerases. This depurination-induced mutagenesis is observed at three different genetic loci and with several different purified enzymes, including Escherichia coli DNA polymerases I and III, avian myeloblastosis virus DNA polymerase, and eukaryotic DNA polymerases alpha, beta, and gamma. The extent of mutagenesis correlates with the estimated frequency of bypass of the lesion and is greatest with inherently inaccurate DNA polymerases which lack proofreading capacity. With E. coli DNA polymerase I, conditions which diminish proofreading result in a 3-5-fold increase in depurination-induced mutagenesis, suggesting a role for proofreading in determining the frequency of bypass of apurinic sites. The addition of E. coli single-stranded DNA-binding protein to polymerase I catalyzed reactions with depurinated DNA had no effect on the extent of mutagenesis. Analysis of wild-type revertants produced during in vitro DNA synthesis by polymerase I or avian myeloblastosis virus DNA polymerase on depurinated phi X174 amber 3 DNA indicates a preference for insertion of dAMP opposite the putative apurinic site at position 587. These results are discussed in relation both to the mutagenic potential of apurinic sites in higher organisms and to studies on error-prone DNA synthesis.     

Analysis of deoxyribonucleic acid replication in human X chromosomes by fluorescence microscopy.

The genetically inactive, late-replicating human female X chromosome can be effectively distinguished from its more active, earlier-replicating homologue, when cells are grown according to the appropriate BrdU-33258 Hoechst protocol. Results obtained from a fluorescence analysis of DNA replication in X chromosomes are consistent with those from previous autoradiographic studies, but reflect additional sensitivity and resolution offered by the BrdU-Hoechst methodology. Both qualitative and quantitative differences in 33258 Hoechst fluorescence intensity, reflecting alterations in replication kinetics, can be detected between the two X chromosomes in female cells. The pattern of replication in the single X chromosome in male cells is indistinguishable from that of the early female X. Intercellular fluctuations in the distribution of regions replicating early or late in S phase, particularly with reference to the late female X, can be localized to structural bands, suggesting multifocal control of DNA synthesis in X chromosomes.     

Four proteins synthesized in response to deoxyribonucleic acid damage in Micrococcus radiodurans.

Four proteins, alpha beta, gamma, and delta, preferentially synthesized in ultraviolet light-treated cells of Micrococcus radiodurans, were characterized in terms of their molecular weights and isoelectric points. Within the sublethal-dose range, the differential rate of synthesis for these proteins increased linearly with the inducing UV dose. The degree of induction reached 100-fold, and the most abundant protein beta, amounted to approximately 2% of the total newly synthesized protein after irradiation. Damage caused by ionizing radiation or by treatment with mitomycin C also provoked the synthesis of the four proteins. The proportions between the individual proteins, however, varied strikingly with the damaging agent. In contrast to treatments which introduced damage in the cellular deoxyribonucleic acid, the mere arrest of deoxyribonucleic acid replication, caused by nalidixic acid or by starvation for thymine, failed to elicit the synthesis of either protein. Repair of deoxyribonucleic acid damage requires that a number of versatile and efficient processes by employed. It is proposed that the induced proteins participate in deoxyribonucleic acid repair in M. radiodurans. Mechanisms are discussed which would allow a differentiated cellular response to damages of sufficiently distinctive nature.     

Spermatogenesis in two patients with the fragile X syndrome

Summary Light and electron microscopic studies on testicular biopsies were carried out in two men, 40 and 44 year old, with the fra(X) form of mental retardation and macroorchidism. Distinct interstitial edema, an increased amount of lysosomal inclusions in Sertoli cells, and disturbance of spermatid differentiation were found in both probands. Additionally, some extent of tubular atrophy was demonstrated in one patient. The impairment of spermatogenesis is discussed with respect to pressure effects on the germinal epithelium due to the edema.     

Spermatogenesis in two patients with the fragile X syndrome

Summary Chromosomes at first meiosis from two males with the fra(X) form of mental retardation were studied using pachytene surface spreads and air-dried preparations. The pachytene sex bivalents showed no discontinuation of the synaptonemal complex in the terminal part of Xq corresponding to band Xq27–28 of the mitotic chromosomes. In both cases the frequency of a secondary association of Xq and Yq appeared to be increased compared with controls. The pairing behavior of autosomal bivalents in pachytene and the frequency and distribution of chiasmata in diakinesis were normal. The impairment of spermatogenesis found in these males may not be caused by a meiotic disorder, but could be related to peritubular or intratubular pressure effects on germ cells.     

Increased oxidative damage to DNA in ALS patients

Although the cause of amyotrophic lateral sclerosis (ALS) is unknown, substantial evidence indicates that oxidative toxicity is associated with neuronal death in this disease. We examined levels of a well-established marker of oxidative damage to DNA, 8-hydroxy-2'-deoxyguanosine (8OH2'dG) in plasma, urine, and cerebrospinal fluid (CSF) at a single time point from subjects with ALS, other neurological diseases, or no known disorders. We also measured the rate of change of 8OH2'dG levels in plasma and urine from ALS and in urine from control subjects over 9 months and examined the relationship to disease severity. In each fluid, 8OH2'dG levels were significantly elevated in the ALS group as compared to control subjects. In all subjects, the plasma and CSF 8OH2'dG levels increased with age, providing further evidence for a role of oxidative damage in normal aging. Plasma and urine 8OH2'dG levels increased significantly with time in the ALS group only. The rate of increase in urine 8OH2'dG levels with time was significantly correlated with disease severity. These findings are consistent with the hypothesis that oxidative pathology accompanies the neurodegenerative process in ALS and suggest that 8OH2'dG may provide a useful tool for monitoring therapeutic interventions in this disease.