Detoxification Of Oxygen Radicals Research Articles

Transcriptome analysis of Epichloë strains in tall fescue in response to drought stress

ABSTRACT Epichloë coenophiala, a systemic fungal symbiont (endophyte) of tall fescue (Lolium arundinaceum), has been documented to confer to this grass better persistence than plants lacking the endophyte, especially under stress conditions such as drought. The response, if any, of the endophyte to imposition of stress on the host plant has not been characterized previously. Therefore, we investigated effects on gene expression by E. coenophiala and a related endophyte when plant-endophyte symbiota were subjected to acute water-deficit stress. Plants harboring different endophyte strains were grown in sand in the greenhouse, then half were deprived of water for 48 h and the other half were watered controls. RNA was isolated from different plant tissues, and mRNA sequencing (RNA-seq) was conducted to identify genes that were differentially expressed comparing stress treatment with control. We compared two different plants harboring the common toxic E. coenophiala strain (CTE) and two non–ergot-alkaloid-producing Epichloë strains in tall fescue pseudostems, and in a second experiment we compared responses of E. coenophiala CTE in plant pseudostem and crown tissues. The endophytes responded to the stress with increased expression of genes involved in oxidative stress response, oxygen radical detoxification, C-compound carbohydrate metabolism, heat shock, and cellular transport pathways. The magnitude of fungal gene responses during stress varied among plant-endophyte symbiota. Responses in pseudostems and crowns involved some common pathways as well as some tissue-specific pathways. The fungal response to water-deficit stress involved gene expression changes in similar pathways that have been documented for plant stress responses, indicating that Epichloë spp. and their host plants either coordinate stress responses or separately activate similar stress response mechanisms that work together for mutual protection.

Effect of sex on gene expression in equine blastocysts

Male mammalian embryos grow faster than female; but in equine, embryo size varies greatly and the relationship to sex and gene expression has not been reported. This study aimed to evaluate gene expression according to sex in equine blastocysts. Nonlactating, Saddlebred mares located on two experimental farms were inseminated with the semen of one stallion. At 8 days post ovulation, 17 and 11 embryos from each farm and each from a different dam, were recovered and bisected to obtain samples of pure trophoblast (TE) or inner cell mass enriched trophoblast (TE-ICM) . RNA expression was analyzed separately in the TE-ICM and the TE of 16 female and 12 male embryos using paired end, non-oriented RNA sequencing (Illumina, NextSeq500). To discriminate gene expression in the ICM from that in the TE, deconvolution (DeMixT) was used on the TE-ICM data. Differential expression was analyzed (DESeq2) with farm and embryo size as cofactors using a false discovery rate (FDR) <0.05 cutoff. Gene Set Enrichment Analysis was performed using the KEGG and GObp databases. Female and male embryo size was comparable (respectively, 968±574 and 1087±519µm). Of the 13,786 and 13,210 genes expressed in ICM and TE, respectively, only 184 (51% on X chromosome) in ICM and 415 (39% on X chromosome) in TE were differentially expressed,with 111 genes in common. Overall, 145 genes in ICM and 312 in TE were significantly upregulated in females including glucose-6-phosphate dehydrogenase (G6PD, log2 Fold Change = 0.96 in ICM and 0.83 in TE; FDR <0.001). G6PD is required for detoxification of oxygen radicals, with both cellular damage and growth-stimulant effects. Reduced levels of oxygen radicals have been hypothesized to be responsible for the growth delay in female bovine embryos. In ICM cells, 16 and 1 gene sets were enriched in male embryos in GObp and KEGG, respectively while 3 KEGG pathways were enriched in female ICM. In TE, 27 and 6 gene sets were enriched in male embryos in GObp and KEGG, respectively, while no pathway was enriched in female embryos. Enriched pathways in males were mostly common between ICM and TE and were involved in translation and spliceosome, ribosome biogenesis, mitochondrial function, cytoskeleton organization, and amino acid metabolism. Pathways that were only enriched in male ICM related to potassium ion homeostasis; while in TE, they were related to protein export. In females, ICM enriched pathways were related to Krebs cycle, glycosaminoglycan degradation and lysosome. Although no size difference was observed, sexual dimorphism exists and includes genes unrelated to the sex chromosomes.

105 Sexual dimorphism in equine D8 blastocysts

In mammals, male embryos grow faster. Equine embryo size is highly variable for same developmental stage, with no reported relation to embryo sex nor gene expression. Our objective was to evaluate gene expression sexual dimorphism on equine D8 blastocysts. Non-nursing, Saddlebred mares located on 2 experimental farms were inseminated with the semen of one unique stallion per farm. At 8 d post ovulation, 17 and 11 embryos from each farm, each from a different dam, were recovered by uterine flushing and bissected to obtain samples of pure (TE) or inner cell mass enriched (TE-ICM) trophoblast. RNA expression was analyzed separately in the TE-ICM and the TE of 16 female and 12 male embryos using paired end, non-oriented RNA sequencing (Illumina, NextSeq500). To discriminate gene expression in the ICM from that in the TE, deconvolution (DeMixT R package) was used on the TE-ICM data. Differential expression was analyzed (DESeq2) with farm and embryo size as cofactors using a false discovery rate (FDR) < 0.05 cutoff. Gene Set Enrichment Analysis was performed using the KEGG and GO BP databases. Out of the 13,786 and 13,210 genes expressed in ICM and TE, respectively, only 184 (51.1% on X chromosome) in ICM and 415 (39.0% on X chromosome) in TE were differentially expressed, with 111 genes in common. Overall, 145 in ICM and 312 in TE genes were significantly upregulated in female. As reported in bovine embryos, glucose-6-phosphate dehydrogenase (G6PD) was upregulated in female (log2 Fold Change = 0.96 in ICM and 0.83 in TE; both FDR <0.001). G6PD is required for detoxification of oxygen radicals that have both cellular damage and growth-stimulant effects. Reduced levels of oxygen radicals have been hypothesized to be responsible for the growth delay in female bovine embryos. In ICM cells, 16 and 1 gene sets were enriched in male embryos in GO BP and KEGG, respectively while 3 KEGG pathways were enriched in female ICM. In the TE part, 27 and 6 gene sets were enriched in male embryos in GO BP and KEGG, respectively, while no pathway was enriched in female embryos. Biological processes enriched in male embryos are mostly common between ICM and TE and are related to translation and spliceosome, ribosome biogenesis, mitochondrial function, cytoskeleton organization and amino acid metabolism. Pathways that were only enriched in male ICM relate to potassium ion homeostasis while in TE, they relate to protein export. In females, enriched pathways in ICM were related to Krebs cycle, glycosaminoglycan degradation and lysosome. Thus, although no growth retardation has been observed in equine female embryo, sexual dimorphism in gene expression of genes unrelated to the sex chromosomes is observed.

Antioxidative defence mechanisms in two grapevine (Vitis vinifera L.) cultivars grown under boron excess in the irrigation water

The aim of this study was to investigate the impact of B excess on the antioxidative defence system in two grapevine cultivars differently sensitive to B, in order to evaluate in which way the different sensitivity was correlated to the activation of defence mechanisms. Two-year-old Vitis vinifera L. plants (‘Merlot’ and ‘Sangiovese’), grafted on the same rootstock, were subjected to B treatment as potted vines, and biochemical determinations were employed to evaluate the antioxidative response. Compared to ‘Sangiovese’, ‘Merlot’ showed a much higher B accumulation and both leaf and peroxidative damages. In B-treated ‘Sangiovese’ the activity of superoxide dismutase did not change compared to control leaves, whereas in ‘Merlot’ a dramatic decrease in the enzyme activity was observed. B increased reduced ascorbate pools in both cultivars, but ascorbate peroxidase activity was enhanced only in ‘Merlot’. In this latter cv. an enhancement of total phenols was also observed. ‘Merlot’ showed a lower ability to contrast B accumulation in leaves than ‘Sangiovese’ evidencing a higher oxidative stress. Even if defence mechanisms were generally activated in ‘Merlot’, they did not counteract efficiently metabolic damages likely due to the dramatic decrease in superoxide dismutase, the first enzyme involved in the detoxification of oxygen radicals.

The Oxidative Stress Network of Mycobacterium tuberculosis Reveals Coordination between Radical Detoxification Systems.

M. tuberculosis (Mtb) survives a hostile environment within the host that is shaped in part by oxidative stress. The mechanisms used by Mtb to resist these stresses remain ill-defined because the complex combination of oxidants generated by host immunity is difficult to accurately recapitulate in vitro. We performed a genome-wide genetic interaction screen to comprehensively delineate oxidative stress resistance pathways necessary for Mtb to resist oxidation during infection. Our analysis predicted functional relationships between the superoxide-detoxifying enzyme (SodA), an integral membrane protein (DoxX), and a predicted thiol-oxidoreductase (SseA). Consistent with that, SodA, DoxX, and SseA form a membrane-associated oxidoreductase complex (MRC) that physically links radical detoxification with cytosolic thiol homeostasis. Loss of any MRC component correlated with defective recycling of mycothiol and accumulation of cellular oxidative damage. This previously uncharacterized coordination between oxygen radical detoxification and thiol homeostasis is required to overcome the oxidative environment Mtb encounters in the host.

Comparison of sulfur transferases in various tissue and mitochondria of rats with type 1 diabetes mellitus induced by streptozotocin

This study aims to investigate the relationship between sulfurtransferase (STS) activities [rhodanese (TST), mercaptopyruvate sulfurtransferase (MST)] involved in the catalysis of several biochemical reactions including detoxification of cyanide (CN−), restructuring of Fe-S cluster in proteins, and detoxification of oxygen radicals. Rats with type 1 diabetes mellitus induced by streptozotocin (STZ) were anesthetized at 14th day, and liver, lung, kidney, and heart tissues were extracted. All samples were homogenized, and mitochondrial parts were separated. Same processes were performed also in the control group, and TST and MST activities were measured in each part. The homogenate MST (MST Homo .) activities of the type 1 diabetes mellitus group were compared with the control group, and a decrease was observed in the lung, liver, and kidney, respectively; at the same time, an increase was seen in the heart tissue. The mitochondrial MST (MST Mito .) activities of rats with type 1 diabetes mellitus group were compared with the control group, and a decrease was found in all tissues. The highest decrease in the TST Mito . level of rats with type 1 diabetes mellitus was observed in kidney tissue. The TST activities of the type 1 diabetes mellitus group were compared with the control group, and a decrease was observed in the liver, lung, and kidney, respectively; at the same time, an increase was seen in the heart tissue. It is demonstrated in the present study that decreases occur both in enzyme levels of tissue homogenates and in mitochondria, of rats with induced type 1 diabetes mellitus. However, these results were not statistically significant. In the presence of these findings, we think that kidney, liver, lung, and heart tissue can be affected by type 1 diabetes in the long term.

Resistance of Bacillus subtilis Spore DNA to Lethal Ionizing Radiation Damage Relies Primarily on Spore Core Components and DNA Repair, with Minor Effects of Oxygen Radical Detoxification

The roles of various core components, including α/β/γ-type small acid-soluble spore proteins (SASP), dipicolinic acid (DPA), core water content, and DNA repair by apurinic/apyrimidinic (AP) endonucleases or nonhomologous end joining (NHEJ), in Bacillus subtilis spore resistance to different types of ionizing radiation including X rays, protons, and high-energy charged iron ions have been studied. Spores deficient in DNA repair by NHEJ or AP endonucleases, the oxidative stress response, or protection by major α/β-type SASP, DPA, and decreased core water content were significantly more sensitive to ionizing radiation than wild-type spores, with highest sensitivity to high-energy-charged iron ions. DNA repair via NHEJ and AP endonucleases appears to be the most important mechanism for spore resistance to ionizing radiation, whereas oxygen radical detoxification via the MrgA-mediated oxidative stress response or KatX catalase activity plays only a very minor role. Synergistic radioprotective effects of α/β-type but not γ-type SASP were also identified, indicating that α/β-type SASP's binding to spore DNA is important in preventing DNA damage due to reactive oxygen species generated by ionizing radiation.

Transcriptomic and proteomic analysis of a compatible tomato-aphid interaction reveals a predominant salicylic acid-dependent plant response

BackgroundAphids are among the most destructive pests in temperate climates, causing significant damage on several crops including tomato. We carried out a transcriptomic and proteomic study to get insights into the molecular mechanisms and dynamics of the tomato response to the Macrosyphum euphorbiae aphid.ResultsThe time course analysis of aphid infestation indicated a complex, dynamic pattern of gene expression. Several biological functions were affected and genes related to the stress and defence response were the most represented. The Gene Ontology categories of the differentially expressed genes (899) and identified proteins (57) indicated that the tomato response is characterized by an increased oxidative stress accompanied by the production of proteins involved in the detoxification of oxygen radicals. Aphids elicit a defense reaction based on the cross-communication of different hormone-related signaling pathways such as those related to the salicylic acid (SA), jasmonic acid (JA), ethylene and brassinosteroids. Among them, the SA-signaling pathway and stress-responsive SA-dependent genes play a dominant role. Furthermore, tomato response is characterized by a reduced accumulation of photosynthetic proteins and a modification of the expression of various cell wall related genes.ConclusionsOur work allowed a more comprehensive understanding of the signaling events and the defense dynamics of the tomato response to aphids in a compatible interaction and, based on experimental data, a model of the tomato–aphid molecular interaction was proposed. Considering the rapid advancement of tomato genomics, this information will be important for the development of new protection strategies.

New insights into Chlamydomonas reinhardtii hydrogen production processes by combined microarray/RNA‐seq transcriptomics

Hydrogen production with Chlamydomonas reinhardtii induced by sulphur starvation is a multiphase process while the cell internal metabolism is completely remodelled. The first cellular response is characterized by induction of genes with regulatory functions, followed by a total remodelling of the metabolism to provide reduction equivalents for cellular processes. We were able to characterize all major processes that provide energy and reduction equivalents during hydrogen production. Furthermore, C.reinhardtii showed a strong transcript increase for gene models responsible for stress response and detoxification of oxygen radicals. Finally, we were able to determine potential bottlenecks and target genes for manipulation to increase hydrogen production or to prolong the hydrogen production phase. The investigation of transcriptomic changes during the time course of hydrogen production in C.reinhardtii with microarrays and RNA-seq revealed new insights into the regulation and remodelling of the cell internal metabolism. Both methods showed a good correlation. The microarray platform can be used as a reliable standard tool for routine gene expression analysis. RNA-seq additionally allowed a detailed time-dependent study of gene expression and determination of new genes involved in the hydrogen production process.

Genome-Wide Transcriptional Analysis of Genes Associated with Acute Desiccation Stress in Anopheles gambiae

Malaria transmission in sub-Saharan Africa varies seasonally in intensity. Outbreaks of malaria occur after the beginning of the rainy season, whereas, during the dry season, reports of the disease are less frequent. Anopheles gambiae mosquitoes, the main malaria vector, are observed all year long but their densities are low during the dry season that generally lasts several months. Aestivation, seasonal migration, and local adaptation have been suggested as mechanisms that enable mosquito populations to persist through the dry season. Studies of chromosomal inversions have shown that inversions 2La, 2Rb, 2Rc, 2Rd, and 2Ru are associated with various physiological changes that confer aridity resistance. However, little is known about how phenotypic plasticity responds to seasonally dry conditions. This study examined the effects of desiccation stress on transcriptional regulation in An. gambiae. We exposed female An. gambiae G3 mosquitoes to acute desiccation and conducted a genome-wide analysis of their transcriptomes using the Affymetrix Plasmodium/Anopheles Genome Array. The transcription of 248 genes (1.7% of all transcripts) was significantly affected in all experimental conditions, including 96 with increased expression and 152 with decreased expression. In general, the data indicate a reduction in the metabolic rate of mosquitoes exposed to desiccation. Transcripts accumulated at higher levels during desiccation are associated with oxygen radical detoxification, DNA repair and stress responses. The proportion of transcripts within 2La and 2Rs (2Rb, 2Rc, 2Rd, and 2Ru) (67/248, or 27%) is similar to the percentage of transcripts located within these inversions (31%). These data may be useful in efforts to elucidate the role of chromosomal inversions in aridity tolerance. The scope of application of the anopheline genome demonstrates that examining transcriptional activity in relation to genotypic adaptations greatly expands the number of candidate regions involved in the desiccation response in this important malaria vector.

Gene variations in GSTM3 are a risk factor for Alzheimer's disease

Oxidative stress is a relevant pathomechanism in Alzheimer's disease (AD) and gene variations in the glutathione S-transferase M3 gene (GSTM3), involved in the detoxification of oxygen radicals, might influence the risk of AD. We investigated the effect of three polymorphisms in GSTM3: rs1332018 (C/A); rs1799735 (del/AGG); rs7483 (G/A), on the risk of AD in 363 AD patients and 358 healthy controls. Single marker association analyses revealed that the AGG/AGG genotype of the GSTM3 rs1799735 (del/AGG) polymorphism was associated with an increased risk of AD ( p = 0.05), especially in the group of APOE4-allele non-carriers ( p = 0.004; OR = 2.07). Examination of the haplotypes identified a two-marker haplotype (C/AGG) consisting of rs1332018 (C/A) and rs1799735 (del/AGG) to increase the risk of AD ( p = 0.029), this effect was also most prevalent in APOE4-allele non-carriers ( p = 0.009; OR = 1.95). The population attributable risk of this haplotype in APOE4-allele non-carriers was 32.2%. Our results suggest that there is a group of AD patients in which variations in metabolism of oxidative stress play an important role.

SOD2 protects neurons from injury in cell culture and animal models of diabetic neuropathy

Hyperglycemia-induced oxidative stress is an inciting event in the development of diabetic complications including diabetic neuropathy. Our observations of significant oxidative stress and morphological abnormalities in mitochondria led us to examine manganese superoxide dismutase (SOD2), the enzyme responsible for mitochondrial detoxification of oxygen radicals. We demonstrate that overexpression of SOD2 decreases superoxide (O 2 − ) in cultured primary dorsal root ganglion (DRG) neurons and subsequently blocks caspase-3 activation and cellular injury. Underexpression of SOD2 in dissociated DRG cultures from adult SOD2 +/− mice results in increased levels of O 2 − , activation of caspase-3 cleavage and decreased neurite outgrowth under basal conditions that are exacerbated by hyperglycemia. These profound changes in sensory neurons led us to explore the effects of decreased SOD2 on the development of diabetic neuropathy (DN) in mice. DN was assessed in SOD2 +/− C57BL/6J mice and their SOD2 +/+ littermates following streptozotocin (STZ) treatment. These animals, while hyperglycemic, do not display any signs of DN. DN was observed in the C57BL/6Jdb/db mouse, and decreased expression of SOD2 in these animals increased DN. Our data suggest that SOD2 activity is an important cellular modifier of neuronal oxidative defense against hyperglycemic injury.

Capturing candidate drought tolerance traits in two native Andean potato clones by transcription profiling of field grown plants under water stress

Candidate traits for drought tolerance were targeted by analyzing water stress responses in two moderately drought-tolerant native Andean potato clones, SA2563 and Sullu ( Solanum tuberosum L. subsp, andigena (Juz, Bukasov) Hawkes) under field conditions. SA2563 exhibited increased root growth under drought, while Sullu retained a higher relative leaf water content. Gene expression profiling using the TIGR 10 K microarray revealed 1713 significantly differentially expressed genes, 186 of these genes were up-regulated in both clones. In addition to these commonly up-regulated genes, each clone induced a specific gene set in response to drought. Gene expression and metabolite analysis pinpointed candidate traits for drought tolerance present either in one or both of the clones under investigation. These traits included osmotic adjustment, changes in carbohydrate metabolism, membrane modifications, strengthening of cuticle and cell rescue mechanisms, such as detoxification of oxygen radicals and protein stabilization. Many of the up-regulated genes have been identified previously in laboratory studies on model plants using shock treatments, and the present study confirms the importance of these factors under field conditions.

ORAL AND DENTAL FINDINGS IN FANCONI'S ANEMIA

Fanconi's anemia is an autosomal recessive disorder characterized by progressive pancytopenia and congenital malformation of the skeleton. This study investigated the oral health status of 15 children with Fanconi's anemia, including oral lesions, gingival and periodontal status, and dental abnormalities. All children in the group were found to have a tendency to develop tooth decay and were in need of dental treatment. Two had aggressive periodontitis. In one patient supernumerary teeth were found, while in another teeth were congenitally missing. The increased tendency toward periodontal disease in patients with Fanconi's anemia may be due not only to the anemia, leukopenia, and defective detoxification of oxygen radicals that are characteristic of the disease itself, but also to medications applied during intense immunosuppressive treatment, such as prednisolone.

The complex oxidative stress response of Bacteroides fragilis: the role of OxyR in control of gene expression

Gram-negative anaerobes in the genus Bacteroides are the predominant members of the GI-tract microflora where they play an important role in normal intestinal physiology. Bacteroides spp. also are significant opportunistic pathogens responsible for an array of intra-abdominal and other infections. Bacteroides fragilis is the most common anaerobic pathogen and it possesses virulence factors such as a capsule and neuraminidase that contribute to its success as a pathogen. Infection occurs when organisms escape from the anaerobic colon to aerobic sites such as the peritoneum where O 2 concentrations average 6%. Thus in addition to the classic virulence factors, resistance to oxidative stress is essential and may be involved in the initiation and persistence of infection. In fact, B. fragilis is highly O 2 tolerant, surviving extended periods (>24 h) of O 2 exposure without a significant affect on viability. For protection against this oxidative stress B. fragilis mounts a complex physiological response that includes induction of >28 proteins involved in detoxification of oxygen radicals, protection of macromolecules, and adaptive physiology. One experimental strategy used to characterize this oxidative stress response is the direct detection of genes and proteins induced during exposure to O 2 or H 2O 2. The methods employed have included RNA differential display to capture unique mRNA transcripts produced during oxidative stress, and native or 2D-gel electrophoresis to isolate and identify newly formed stress-induced proteins. Using these and other approaches a wide array of genes induced by oxidative stress have been discovered. These include genes for catalase, superoxide dismutase, thioredoxin-peroxidase, p20-peroxidase, cytochrome c peroxidase, Dps, alkyl hydroperoxidase, aerobic ribonucleotide reductase, ruberythrin, starch utilization, aspartate decarboxylase, and an RNA binding protein. The genes encoding these activities fall into three regulatory classes: (1) induced by O 2 only, (2) induced by H 2O 2 only, and (3) induced by either O 2 or H 2O 2. Such a complex regulatory response will likely involve multiple regulators. Thus far one regulator has been identified, OxyR, which controls a subset of the class 3 genes that are induced by either O 2 or H 2O 2. OxyR responds rapidly to oxidative stress and transcriptional analyses have shown that OxyR-controlled genes are activated by as little as 0.5% O 2 or 10 μM H 2O 2. Maximal expression of most OxyR regulon genes was reached at 50 μM H 2O 2 and 2% O 2. These oxidant concentrations are similar to environmental levels that would be experienced by the organisms in tissues outside of the colon suggesting that the OxyR regulon would be induced during the course of an infection.

Iron-dependent transcription of the frpB gene of Helicobacter pylori is controlled by the Fur repressor protein.

We have overexpressed and purified the Helicobacter pylori Fur protein and analyzed its interaction with the intergenic regions of divergent genes involved in iron uptake (frpB and ceuE) and oxygen radical detoxification (katA and tsaA). DNase I footprint analysis showed that Fur binds specifically to a high-affinity site overlapping the P(frpB) promoter and to low-affinity sites located upstream from promoters within both the frpB-katA and ceuE-tsaA intergenic regions. Construction of an isogenic fur mutant indicated that Fur regulates transcription from the P(frpB) promoter in response to iron. In contrast, no effect by either Fur or iron was observed for the other promoters.

Developmental kinetics of in vitro produced bovine embryos: the effect of sex, glucose and exposure to time-lapse environment.

In this study, a simple time-lapse video recording system was used to compare developmental kinetics of female and male bovine embryos produced in vitro. Following embryo sex determination, the timing of each cleavage up to the 4-cell stage was compared between the sexes from the videotapes after culture in the presence and absence of glucose. In the second experiment, the consequences of exposure to a time-lapse video recording (TL) environment were studied by culturing embryos further until day 7 in an incubator, followed by collection and sex determination of morulae and blastocysts. In the absence of glucose, female embryos cleaved earlier than male ones. In the presence of glucose, however, male embryos cleaved earlier than female ones. There was no difference in the number of morulae/blastocysts in the absence of glucose, but in the presence of glucose more male than female embryos reached the morula and blastocyst stage. Exposure to the TL environment itself also had a sex-related effect, being more detrimental to male than female embryos. The difference in the number of functional X chromosomes between the sexes during early preimplantation development could explain these findings. In females, an increased capacity for oxygen radical detoxification through the pentose phosphate pathway could result in a reduced cleavage rate. Furthermore, glucose may influence the expression of enzymes located on the X chromosome. According to these results, a simple time-lapse video recording system is suitable for investigating embryo developmental kinetics and perhaps for the selection of embryos with the greatest developmental potential.

Rheumatoid arthritis and metal compounds--perspectives on the role of oxygen radical detoxification.

Rheumatoid arthritis (RA) is characterised by migration of activated phagocytes and other leukocytes into synovial and periarticular tissue. Activated oxygen species and other mediating substances from triggered phagocytes appear to exacerbate and perpetuate the rheumatoid condition. Iron excesses are capable of aggravating the arthritic inflammation, probably through their pro-oxidant potentials. In contrast, therapeutically given gold salts, through a lysosomal loading of the metal, inhibit the triggered cells, thereby reducing the toxic oxygen production. Pharmacological doses of zinc also may immobilise macrophages. Furthermore, the copper-zinc-containing enzyme SOD (superoxide dismutase) can act as a scavenger of toxic oxygen in the tissues. Therapeutic remission of RA has been obtained following intraarticular administration of SOD. Intramuscular administration of copper complexes has induced remission in about 60% of RA patients in open studies. Another drug, penicillamine, that protects cellular membranes against toxic oxygen in vitro, is presumed to act as an antirheumatic via the SOD mimetic activity of its copper complex. Thiomalate and other thiols may possess similar activities. Selenium compounds also may act as oxygen radical scavengers. A significant alleviation of articular pain and morning stiffness was obtained following selenium and vitamin E supplementation in a double-blind study on RA patients. The observations reviewed here indicate that metal compounds and other antioxidants can reduce the rheumatic inflammation by reducing the cellular production and/or concentration of toxic oxygen species.

Oxidant-Antioxidant Balance in Granulocytes During ARDS: Effect of N-Acetylcysteine

The production of cytotoxic oxygen radicals by activated granulocytes is a proposed mechanism of lung injury in ARDS. Protective effects of N-acetylcysteine (NAC) have been described in experimental and clinical ARDS. NAC could act in part by replenishing the intracellular stores of glutathione (GSH) in activated granulocytes, leading to detoxification of oxygen radicals produced by these cells. To test this hypothesis, 16 patients in the early phase of ARDS were randomized to receive either NAC (n=8) or placebo (n=8); granulocyte GSH, granulocyte oxygen radical production, and plasma levels of granulocyte elastase were measured in blood samples drawn sequentially within 8 h after the onset of ARDS (day 0), and then 24 (day 1), 72 (day 3), and 120 h (day 5) after the first sample; treatment with NAC or placebo was started immediately after day 0 and stopped just after day 3. Granulocyte GSH was significantly higher on days 1 and 3 when NAC was received by the patient. Unstimulated oxygen radical production, as measured <i>ex vivo</i> by luminol- and lucigenin-amplified chemiluminescence (CL), was higher in granulocytes from ARDS patients than from healthy control subjects, but was not influenced by NAC. The plasma levels of granulocyte elastase were five to eight times above the upper normal limit on day 0, decreased steadily until day 5, and were uninfluenced by NAC. In summary, parenteral NAC treatment started within 8 h of diagnosis increases the intracellular GSH in the granulocytes of ARDS patients without decreasing spontaneous oxidant production by these cells. The mechanisms of the protective effects of this drug previously reported in experimental and clinical ARDS remain to be established.

Oxygen radical detoxification processes during aging: the functional importance of melatonin.

That free radical destruction of macromolecules is a basis of aging and age-related diseases has considerable experimental support. Melatonin, a hormone produced in organisms as diverse as algae and humans, is believed to have evolved coincident with aerobic metabolism. In all organisms melatonin is produced primarily during the daily period of darkness, with only small amounts being synthesized during the day. In mammals including man, melatonin is produced by and secreted from the pineal gland during the night; however, the night-time production of melatonin falls markedly with aging such that in senescent animals a night-time melatonin rise is barely measurable. This may be significant in terms of aging in the light of recent observations which show that melatonin is a highly efficient free radical scavenger and antioxidant both in vitro and in vivo. In vitro, melatonin has been shown to directly scavenge both the hydroxyl and peroxyl radical, and it does so more efficiently than other known antioxidants. Furthermore, melatonin greatly potentiates the efficiency of previously-discovered endogenous and exogenous antioxidants. In vivo, both physiological and pharmacological levels of melatonin reportedly counteract the devastatingly destructive actions of free radical generating chemicals. For example, melatonin effectively combats DNA damage in rats given massive doses of the chemical carcinogen safrole, and the indole overcomes much of the genomic damage inflicted by ionizing radiation. Also, lipid peroxidation induced by either paraquat, bacterial lipopolysaccharide or H2O2 is highly significantly reduced by concurrent melatonin administration. Finally, cataracts produced in newborn rats by the depletion of the endogenous antioxidant glutathione are prevented by melatonin. These findings provide evidence that melatonin is operative in the cell nucleus, in the aqueous cytosol and in lipid-rich cellular membranes as an antioxidant. Considering this, the loss of this potent antioxidant during aging may be consequential in terms of cellular and organismal aging as well as the onset of age-related diseases. These experimental results from a variety of sources suggest that a more determined approach to the study of melatonin as an anti-aging factor is warranted.