Knowledge, actual and potential use of HIV self-sampling testing kits among MSM recruited in eight European countries.

AIM: To describe the knowledge as well as current and potential use of self-sampling kits among men who have sex with men (MSM) and to analyse their preferred biological sample and result communication method. METHODS: We analyse data of MSM of HIV negative or unknown serostatus from an online survey conducted in eight countries (Belgium, Denmark, Germany, Greece, Portugal, Romania, Slovenia and Spain) between April and December 2016. It was advertised mainly in gay dating websites. We conduct a descriptive analysis of the main characteristics of the participants, and present data on indicators of knowledge, use and potential use of HIV self-sampling as well as their preferences regarding blood or saliva sample and face or non-face-to-face result communication by country of residence. RESULTS: A total of 8.226 participants of HIV negative or unknown serostatus were included in the analysis. Overall, 25.5% of participants knew about self-sampling (range: 18.8-47.2%) and 1.1% had used it in the past (range: 0.3-8.9%). Potential use was high, with 66.6% of all participants reporting that they would have already used it if available in the past (range: 62.1-82.1%). Most (78.6%) reported that they would prefer using a blood-based kit, and receiving the result of the test through a non-face-to-face-method (70.8%), even in the case of receiving a reactive result. CONCLUSION: The high potential use reported by MSM recruited in eight different European countries suggests that self-sampling kits are a highly acceptable testing methodology that could contribute to the promotion of HIV testing in this population.

Effectiveness of rosuvastatin plus colchicine, emtricitabine/tenofovir and combinations thereof in hospitalized patients with COVID-19: a pragmatic, open-label randomized trial.

BACKGROUND: The use of rosuvastatin plus colchicine and emtricitabine/tenofovir in hospitalized patients with SARS-CoV-2 disease (COVID-19) has not been assessed. The objective of this study was to assess the effectiveness and safety of rosuvastatin plus colchicine, emtricitabine/tenofovir, and their combined use in these patients. METHODS: This was a randomized, controlled, open-label, multicentre, parallel, pragmatic study conducted in six referral hospitals in Bogotá, Colombia. The study enrolled hospitalized patients over 18 years of age with a confirmed diagnosis of COVID-19 complicated with pneumonia, not on chronic treatment with the study medications, and with no contraindications for their use. Patients were assigned 1:1:1:1. 1) emtricitabine with tenofovir disoproxil fumarate (FTC/TDF, 200/300 mg given orally for 10 days); 2) colchicine plus rosuvastatin (COLCH+ROSU, 0.5 mg and 40 mg given orally for 14 days); 3) emtricitabine with tenofovir disoproxil plus colchicine and rosuvastatin at the same doses and for the same period of time (FTC/TDF+COLCH+ROSU); or 4) the Colombian consensus standard of care, including a corticosteroid (SOC). The primary endpoint was 28-day all-cause mortality. A modified intention-to-treat analysis was used together with a usefulness analysis to determine which could be the best treatment. The trial was registered at ClinicalTrials.gov: NCT04359095. FINDINGS: Out of 994 candidates considered between August 2020 and March 2021, 649 (65.3%) patients agreed to participate and were enrolled in this study; among them, 633 (97.5%) were included in the analysis. The mean age was 55.4 years (SD ± 12.8 years), and 428 (68%) were men; 28-day mortality was significantly lower in the FTC/TDF+COLCH+ROSUV group than in the SOC group, 10.7% (17/159) vs. 17.4% (28/161) (hazard ratio [HR] 0.53; 95% CI 0.29 to 0.96). Mortality in the FTC/TDF group was 13.8% (22/160, HR 0.68, 95% CI 0.39 to 1.20) and 14.4% in the COLCH+ROSU group (22/153) (HR 0.78, 95% CI 0.44 to 1.36). A lower need for invasive mechanical ventilation was observed in the FTC/TDF+COLCH+ROSUV group than in the SOC group (risk difference [RD] - 0.08, 95% CI 0.11 to 0.04). Three patients presented severe adverse events, one severe diarrhoea in the COLCH+ROSU and one in the FTC/TDF+COLCH+ROSU group and one general exanthema in the FTC/TDF group. INTERPRETATION: The combined use of FTC/TDF+COLCH+ROSU reduces the risk of 28-day mortality and the need for invasive mechanical ventilation in hospitalized patients with pulmonary compromise from COVID-19. More randomized controlled trials are needed to compare the effectiveness and cost of treatment with this combination versus other drugs that have been shown to reduce mortality from SARS-CoV-2 infection and its usefulness in patients with chronic statin use.

Effect of two different pre-anaesthetic omeprazole protocols on gastroesophageal reflux incidence and pH in dogs.

OBJECTIVES: Gastroesophageal reflux can occur during anaesthesia and may lead to esophagitis and occasionally oesophageal stricture formation. The aim of the study is to assess two omeprazole protocols on gastroesophageal reflux incidence and pH in anaesthetised dogs. MATERIALS AND METHODS: Fifty-five dogs undergoing elective ovariectomy were randomly assigned to: omeprazole single dose 1 mg/kg orally the evening before anaesthesia (20 dogs), omeprazole two doses 1 mg/kg orally the evening and 3 hours before anaesthesia (15 dogs), and control group that did not receive omeprazole (20 dogs). An oesophageal impedance/pH probe was used to measure gastroesophageal reflux incidence and pH during anaesthesia. RESULTS: Gastroesophageal reflux was observed in 55% (11/20) of control dogs, 55% (11/20) of dogs receiving omeprazole once and 47% (7/15) of dogs receiving omeprazole twice. The incidence was not statistically significant different between groups. Gastroesophageal reflux pH (mean ± sd) was higher in dogs receiving omeprazole twice (6.3 ± 1.5), when compared to either control dogs (3.8 ± 1.1) or dogs receiving omeprazole once (4.1 ± 1.5). Strongly acidic reflux (pH < 4) was observed in 7% (1/15) of dogs receiving omeprazole twice versus 55% (11/20) and 35% (7/20) of control dogs and dogs receiving omeprazole once, respectively. CLINICAL SIGNIFICANCE: Omeprazole administered the evening and 3 hours before anaesthesia increased gastroesophageal reflux pH and decreased the incidence of strongly acidic reflux in dogs. A single dose of omeprazole given the evening before anaesthesia had no effect on reflux pH.

Interaction of lipid peroxidation products with nuclear macromolecules.

The interaction of lipid peroxidation products with nuclear macromolecules was investigated in rat liver nuclei labelled with [3H]arachidonic acid. Lipid peroxidation reactions were driven both non-enzymatically and enzymatically by the addition of ascorbate-Fe2+ or NADPH-ADP-Fe3+, respectively, to the incubation mixtures. The extent of peroxidation was evaluated by the formation of thiobarbituric acid chromophore and of radioactive hydrophilic peroxidation products. The results obtained show that: (1) nuclear membrane lipid peroxidation products formed during incubation interact with DNA and total nuclear proteins; (2) non-enzymatic lipid peroxidation processes induced a 40% larger association of peroxidation products to DNA compared to processes driven enzymatically, whereas the corresponding interaction with total nuclear proteins was similar in both peroxidation systems; (3) the radioactivity associated with histones decreased during incubation in the presence of ascorbate-Fe2+ or NADPH-ADP-Fe3+, and increased in control samples (no additions); (4) inhibition of lipid peroxidation by the iron chelator Desferrioxamine B prevented the association of peroxidation products to nuclear macromolecules; (5) the levels of radioactivity found in DNA after 180 min of incubation would represent the formation of 0.6-1.0 adducts per 10(6) DNA bases. The results obtained provide evidence for an interaction between lipid peroxidation products and chromatin in the interior of the cell nucleus.

Studies on lipid peroxidation in rat liver nuclei and isolated nuclear membranes.

Non-enzymatic and enzymatically-driven lipid peroxidation processes were studied in rat liver nuclei and isolated nuclear membranes, by evaluating the formation of thiobarbituric acid-chromophore, free malondialdehyde, lipofuscin-like pigments, and the degradation of polyunsaturated fatty acids of the nuclear membrane lipids. The results obtained show that: (1) both non-enzymatic and enzymatically driven lipid peroxidation processes are operative in cell nuclei and isolated nuclear membranes; (2) only for isolated nuclear membranes, a good qualitative and up to a great extent quantitative correlation between malondialdehyde and lipofuscin-like pigment formation was obtained; (3) there is a qualitative but not quantitative correlation between malondialdehyde formation and polyunsaturated fatty acid degradation; (4) lipid peroxidation processes in isolated nuclear membranes and intact nuclei have an essentially identical kinetic behaviour. No statistical differences in the relative increases in the concentrations of malondialdehyde and lipofuscin-like pigments or in the degradation of polyunsaturated fatty acids were obtained, when the two systems were compared, except in the presence of NADPH-ADP-Fe3+, which induced a significantly larger degradation of polyunsaturated fatty acids in isolated nuclear membranes than in intact nuclei, and (5) no malondialdehyde-DNA fluorescent adduct formation was observed in any of the experimental groups studied, as inferred from the characteristics of the fluorescent spectra of lipofuscin-like pigments extracted from incubated nuclear preparations.

High dietary omega-6 polyunsaturated fatty acids drastically increase the formation of etheno-DNA base adducts in white blood cells of female subjects.

Lipid peroxidation generates reactive aldehydes such as trans-4-hydroxy-2-nonenal and malonaldehyde, which form promutagenic exocyclic DNA adducts in human cells and may contribute to diet-related cancers. Using ultrasensitive detection methods, analysis of WBC DNA from volunteers in a dietary study revealed that high intake of omega-6 polyunsaturated fatty acids increased malonaldehyde-derived adducts in male and female subjects. In contrast, etheno adducts (1,N6-ethenodeoxyadenosine; 3,N4-ethenodeoxycytidine) were not elevated in males but were, on average, 40 times higher in females, displaying a huge intersubject variation in lipid peroxidation-derived DNA damage. Exocyclic DNA adducts are promising biomarkers for examining the hypothesis of possible links between increased intake of dietary omega-6 polyunsaturated fatty acids, DNA damage, and elevated cancer risk for breast, colon, and prostate.

Adrenal insufficiency occurring during septic shock: incidence, outcome, and relationship to peripheral cytokine levels.

PURPOSE: In patients with septic shock, to (1) determine the incidence of adrenal insufficiency (AI), (2) observe the effects of glucocorticoid therapy on outcome in those with impaired adrenal function, and (3) investigate a possible correlation between adrenal function and peripheral cytokine levels. PATIENTS AND METHODS: Twenty-one patients admitted to the medical and surgical intensive care unit with septic shock and 11 healthy volunteers were studied. Cortisol, tumor necrosis factor-alpha (TNF-alpha), and interleukin-6 (IL-6) levels were measured before and after infusion of low (1 microgram) and standard doses (250 micrograms) of adrenocorticotropic hormone (ACTH) within 24 hours of the diagnosis of septic shock. Patients with subnormal adrenal responses to ACTH were treated with stress doses of steroids. Hormone, cytokine, and survival data in patients with normal response were compared to those with subnormal adrenal function. RESULTS: Five patients (23.8%) exhibited AI by ACTH stimulation testing. Three of them received steroid supplementation with rapid improvement in hemodynamic parameters. Autopsies of 2 patients with AI revealed intact adrenal cortices. Sixteen patients had adequate adrenal responses (AAR) to the standard-dose ACTH infusion. TNF-alpha levels were inversely correlated with mean arterial pressure (MAP) (r = -.52, P = 0.038) in AAR but not AI. There was no difference in mean peripheral TNF-alpha levels between AAR and AI. There was no correlation between TNF-alpha levels and mortality or adrenal function in those with septic shock. A trend toward lower IL-6 levels in AI suggests a link between reduced IL-6 levels and understimulation of the pituitary-adrenal axis in this group. Mortality in patients with AI was 80% at 4 weeks as compared with 43.8% in the group with normal adrenal response. CONCLUSIONS: Adrenal hyporesponsiveness is a feature of septic shock in some patients. Its etiology is probably complex. Steroid supplementation appeared to improve short-term survival when AI occurred, although these patients' overall mortality was worse than that of patients with septic shock and AAR. The standard-dose (250 micrograms) rapid ACTH infusion test was adequate for detecting AI. Adrenal insufficiency should be suspected in patients with septic shock who do not respond to conventional treatment. Performing the ACTH infusion test and initiating a trial of stress doses of glucocorticoids pending the results is a reasonable strategy in this situation.

Lipid peroxide levels in a murine adenocarcinoma exposed to hyperthermia: the role of glutathione depletion.

Increased lipid peroxide levels were obtained 1 h after a 60-min 43 degrees C hyperthermia treatment of a solid murine C3H mammary adenocarcinoma, grown subcutaneously in the hind paws of mice. Previous work from our group revealed that this heat treatment depletes the intracellular glutathione (GSH) content in this tumor. To investigate GSH depletion as one tentative mechanism behind the increased lipid peroxide levels obtained, we also measured the formation of lipid peroxidation products after extensive DL-buthionine-S,R-sulfoximine (BSO)-induced GSH depletion. The lipid peroxide effect provoked by BSO was less than that of the 60-min hyperthermia treatment. We therefore propose that the increased lipid peroxide levels induced by heat treatment do not correlate primarily with the observed decrease in GSH levels. Furthermore, in thermotolerance-induced tumors, lipid peroxide levels after a second heat treatment were observed to increase concomitantly with the cessation of thermotolerance. Lipid peroxide levels were also studied in liver, lung, and heart. Following BSO treatments, and up to 2-fold increase was observed in these organs in non-tumor-bearing mice. It was also observed that the intrinsic lipid peroxide levels in these organs from tumor-bearing mice were approximately 1.5- to 4-fold higher in comparison with non-tumor-bearing mice, thus indicating a systemic effect of the tumor implant.

Methylglyoxal induces hprt mutation and DNA adducts in human T-lymphocytes in vitro.

Methylglyoxal (MG) is a mutagen present in several foodstuffs, including coffee. We have used the 32P-postlabelling method to measure MG-deoxyguanosine adduct levels, and the T-cell cloning technique, to study the frequency of hprt (hypoxanthine-guanine phosphoribosyl transferase) mutant cells after treatment of human lymphocytes with MG in vitro. The mutant induction by single (18 hr) high-dose (1.0-1.5 mM) treatment was comparable to that induced by repeated (3 x 48 hr) low-dose (0.1-0.4 mM) treatment. The latter also correlated with the adduct levels measured in the same experiment. The relative cell survival measured by direct cloning after the final treatment agreed well with the growth curves monitored during the expression phase. Our results show that MG is capable of inducing hprt mutations as well as DNA adducts in human lymphocytes at doses with low cytotoxicity. However, significant adduct formation (two- to threefold) could be obtained only after the first exposure in cells subjected to a repeated treatment protocol, and the induced mutant frequency was low (two- to fourfold over background). Thus, MG seems to be a comparatively weak mutagen in this system.

Incorporation of [3H]acetate into the membrane lipids of a murine tumour during the development of thermotolerance.

The incorporation of [3H]acetate into the membrane lipids of a C3H mammary adenocarcinoma, grown s.c. in the hind paw of CBA mice, was followed to estimate the effects on the de novo synthesis of membrane lipids after hyperthermic treatments. Thermotolerance developed in response to a heat treatment at 43 degrees C for 20 min, as verified through growth rate studies of tumours exposed to fractionated heat treatments. Our results show that, during the development of thermotolerance, the relative rates of incorporation of [3H]acetate into the major lipid classes of the tumour cell membranes change significantly. The de novo synthesis of phospholipids decreased while that of cholesteryl esters plus triglycerides increased. The incorporation of [3H]acetate into cholesterol remained constant. Consequently, the ratio [3H]cholesterol/[3H]lecithin increased significantly during the development of thermotolerance. When the incorporation of [3H]acetate was followed 72-96 h after the heat treatment, i.e. at the interval at which heat resistance was observed to approach that of control tumours, the incorporation into cholesterol was significantly reduced while incorporation into phospholipids increased to control levels. Thus, the ratio [3H]cholesterol/[3H]lecithin was significantly lower, when compared to that of control tumours. The functional relationship between the heat-induced changes in the de novo synthesis of membrane lipids and the development of thermotolerance is discussed with regard to a mechanism based on homeoviscous adaptation of the membranes.

Studies of the reaction of acetaldehyde with deoxynucleosides.

The reaction of acetaldehyde with deoxynucleosides was studied in buffered solutions at room temperature (22-24 degrees C) and neutral pH. Reaction products were obtained with all deoxynucleosides with the exception of thymidine, as shown by reversed-phase HPLC analysis. The order of reactivity was dGuo > dAdo > dCyd, for which three, two and one reaction products, respectively, were obtained. We report here data on the kinetics of the reactions, the stability of the adducts at physiological pH, product yields, UV-spectroscopic data at different pH values, and describe the synthesis, isolation and structural characterization by FAB/MS and NMR of the stable adducts of acetaldehyde with dGuo. Furthermore, the formation of adducts with dGuo by the cooperative reaction of Aa with ethanol was studied.

Synthesis of fluorescent derivatives of 7-methylguanine through reaction with 2-aryl-substituted malondialdehydes: analysis by HPLC with fluorescence detection.

Fluorescent derivatives of 7-methylguanine were prepared through reaction with 2-aryl-substituted-malondialdehydes and analysed by reversed-phase HPLC with fluorescence detection. Reaction of carbons 1 and 3 of the malondialdehyde molecule at the N1 and N2 positions of 7-methylguanine yielded fluorescent tricyclic structures. Two novel fluorescent derivatives of 7-MeG were obtained, namely, 7-(3,4-dimethoxyphenyl)-10-oxo-1-methyl-9,10-dihydropyrimido[1,2- alpha]purine (yield 15-34%) and 7-(1-naphthyl)-10-oxo-1-methyl-9,10- dihydropyrimido[1,2-alpha]purine (yield 56-70%) after reaction with 3,4-dimethoxyphenylmalondialdehyde and 1-naphthylmalondialdehyde, respectively which were characterized by IR, NMR, MS and UV and fluorescence spectroscopy. The fluorescence intensity of the derivatives was found to be 10-20-fold higher than the intrinsic fluorescence of 7-methylguanine. Concentration versus fluorescence intensity curves exhibit linearity in the picomole to nanomole range. The 2-aryl-substituted malondialdehydes were used to analyse the concentration of 7-methylguanine in neutral hydrolysates obtained from calf thymus DNA samples alkylated with dimethyl sulfate. The results obtained indicate their potential as reagents for the analysis of alkylated guanines in biological samples. Molecular modeling calculations were carried out to generate lowest energy spatial configurations. The results obtained indicated that the aryl-substituents on the malondialdehyde moiety do not lie in the same plane as the tricyclic moiety of the fluorescent derivatives with implications for their fluorescence properties.

Formation of DNA adducts in human buccal epithelial cells exposed to acetaldehyde and methylglyoxal in vitro.

Acetaldehyde (AA) and methylglyoxal (MG) are reactive, ubiquitous aldehydes, present in the environment and endogenously formed in animals and humans. They have both been shown to readily form DNA adducts under simulated physiological conditions. We report here on the use of cultured normal and SV40T antigen-immortalized human buccal epithelial cells as model systems for aldehyde exposure of the oral epithelium, occurring through the ingestion of alcoholic beverages and brewed coffee, as well as by inhalation of tobacco smoke and automobile exhaust. By the application of recently developed 32P-postlabeling methods, the presence of both endogenous and induced AA and MG DNA adducts was demonstrated in cultured human epithelial cells. Furthermore, these DNA adducts were formed in a dose-dependent manner at aldehyde concentrations that were relatively nontoxic to the cells.

Lipid peroxidation in the rat-liver S9 fraction: influence of membrane lipid composition.

These studies describe the influence of membrane fatty acid composition on peroxidation processes in rat-liver S9 fractions. Lipid peroxidation may be expected to affect enzyme activity and cofactors of importance for the performance of the Salmonella Mutagenicity Test, as well as to contribute to the formation of chemically reactive degradation products that are mutagenic. Lipid peroxidation products were measured as derivatives of 2-thiobarbituric acid (TBA). The amount of TBA-reactive compounds (TBA-C), formed during incubation of S9 fractions from rats fed a diet containing sunflower-seed oil, was 8 times higher than that produced in S9 fractions prepared from rats fed diets containing coconut oil or hydrogenated lard as their only sources of fat. S9 fractions from livers of Aroclor 1254 treated rats showed a marked increase in peroxidation yields for all 3 dietary groups investigated as compared to S9 fractions from non-induced animals. The coconut oil and hydrogenated lard dietary groups showed a 13-fold increase in the yield of TBA-reactive material, while a 2-fold increase was found for the sunflower-seed oil group. The variations in the glutathione (GSH) levels and the degradation of unsaturated fatty acids were also studied in response to Aroclor 1254 treatment, fatty acid composition of the diets and incubation at 37 degrees C. Pronounced variations in the GSH levels were observed in response to Aroclor 1254 treatment and incubation conditions. A positive correlation between production of TBA-reactive material and degradation of unsaturated fatty acids was verified for S9 fractions from the coconut oil and hydrogenated lard dietary groups. Furthermore, the effect of Fe2+ on lipid peroxidation was studied in all 3 dietary groups. The rate of lipid peroxidation was increased in all groups but only the coconut oil and hydrogenated lard dietary groups showed increased total yields of TBA-C upon administration of Aroclor 1254 to rats. Lipid peroxidation processes cause chemical alterations in liver homogenates. Therefore, these effects ought to be considered both in the preparation and in the use of the S9 fraction in different test systems.

32P-postlabelling analysis of DNA adducts in humans: adduct distribution and method improvement.

32P-Postlabelling was applied to study the distribution of adducts in white blood cells of foundry workers exposed to polycylic aromatic hydrocarbons. The distribution of the adducts among 63 workers followed an apparently trimodal pattern, which could relate to polymorphism in PAH metabolism. A modified postlabelling method is described and some parameters were tested for optimal labelling. The total volume of the polynucleotide kinase reaction is 2 microliters, which decreases exposure to radioactivity and costs of isotopes.

Development of a 32P-postlabelling method for the analysis of adducts arising through the reaction of acetaldehyde with 2'-deoxyguanosine-3'-monophosphate and DNA.

A 32P-postlabelling assay was developed for the analysis of adducts arising from the reaction of 2'-deoxyguanosine-3'-monophosphate with acetaldehyde, the primary oxidative metabolite of ethanol. The 32P-postlabelling reaction was optimized by testing various parameters such as the kinetics of phosphorylation by T4 polynucleotide kinase, substrate-concentration-dependent labelling efficiency and the concentration of the various ingredients of the phosphorylation reaction. The sensitivity to 3'-monophosphate dephosphorylation activity of nuclease P1 was also studied. Three stable adducts were separated by reversed-phase HPLC. The major stable adduct was structurally characterized and identified as N2-ethyl-2'-deoxyguanosine and could be detected, after reduction with NaBH4 or a mixture of ascorbic acid and GSH, in calf thymus DNA samples that had been reacted in vitro with acetaldehyde. DNA adducts were isolated after enzymatic digestion to mononucleotides followed by nuclease P1 digestion of normal nucleotides. The average levels of acetaldehyde-DNA adducts detected in these samples were 12.1 +/- 2.3 (n = 17) and 4.9 +/- 0.9 (n = 9) adducts/10(7) nucleotides after reduction with NaBH4, or ascorbic acid and GSH respectively. The 32P-postlabelling method was further validated by the detection of acetaldehyde adducts in liver DNA from mice treated with ethanol. The average concentration of the adducts detected in these animals was 1.5 +/- 0.8 (n = 7) adducts/10(8) nucleotides, as analyzed by reversed-phase HPLC with online detection of radioactivity.

Detection of DNA adducts of acetaldehyde in peripheral white blood cells of alcohol abusers.

The effect of alcohol drinking on the formation of DNA adducts of acetaldehyde, the primary oxidative metabolite of ethanol, was investigated in humans. DNA was isolated from granulocytes and lymphocytes from 24 alcoholic patients and 12 control subjects. DNA adduct levels were measured by 32P-postlabelling using reversed-phase HPLC with on-line detection of radioactivity. A large interindividual variation in adduct levels was observed. The average adduct levels in granulocyte and lymphocyte DNA from alcoholic patients were 3.4 +/- 3.8 and 2.1 +/- 0.8 adducts/10(7) nucleotides (n = 24), respectively. These levels were 13- and 7-fold higher than the corresponding levels in control subjects (P<0.001). The average adduct level in granulocyte DNA from alcoholic patients was 60% higher than in lymphocyte DNA (P<0.01). Our results, in conjunction with the genotoxicity of acetaldehyde, thus suggest the formation of DNA adducts of acetaldehyde as a plausible mechanism explaining the involvement of alcohol drinking in carcinogenesis.

Nuclear membrane lipid peroxidation products bind to nuclear macromolecules.

Ascorbate-Fe2+-driven lipid peroxidation processes in isolated rat liver nuclei give rise to products that bind to DNA and total nuclear proteins. This has been demonstrated by integrating [3H]arachidonic acid into the nuclear membranes. Lipid peroxidation was estimated from the formation of 2-thiobarbituric acid chromophore, and from the relative distribution of 3H-peroxidation products between the lipidic fraction and the nonlipidic fraction of the nuclear suspensions during incubation. The amount of 3H-peroxidation products associated with DNA and total nuclear proteins increased about threefold, when compared to control experiments (no ascorbate-Fe2+), after 180 min of incubation. In contrast, the radioactivity associated with the histone fraction was observed to decrease during incubation. The positive correlation obtained between the formation of thiobarbituric acid chromophore and the association of radioactivity with DNA and nuclear proteins indicates that the binding processes were dependent on peroxidation of the nuclear membrane lipids.

Studies on the relationship between hemoglobin and DNA adducts of malonaldehyde and their stability in vivo.

The stability of the adducts of malonaldehyde (MA) to N-terminal valine in hemoglobin (Hb) and to guanine at N1,N2 in liver DNA was determined in vivo. Mice were injected with radiolabeled or unlabeled MA and the decay of the levels of Hb and DNA adducts was determined using the N-alkyl Edman method and the 32P-postlabeling assay respectively. The rate of adduct formation was much higher towards valine in Hb than towards guanine in DNA. The highest level of adducts to valine was observed 4 h after the treatment, whereas the corresponding level for guanine was after approximately 120 h. The adduct to guanine in DNA was significantly more stable. The estimated half-lives of the adduct to N-terminal valine in Hb and for the adduct to guanine in DNA were approximately 6 and approximately 12.5 days respectively. The persistence of DNA adducts from MA in liver indicates that this type of adduct is poorly recognized by DNA repair enzymes and thus may accumulate during chronic exposure.