Forkhead box A2-mediated lncRNA SOX2OT up-regulation alleviates oxidative stress and apoptosis of renal tubular epithelial cells by promoting SIRT1 expression in diabetic nephropathy

BACKGROUND

Renal tubular injury is the main feature of diabetic nephropathy (DN). We intend to investigate the function and related mechanisms of lncRNA SOX2 overlapping transcript (SOX2OT) in high glucose (HG)-induced oxidative stress and apoptosis of renal tubular epithelial cells (RTECs).

METHODS

To construct diabetes models, the human kidney-2 (HK-2) cells were treated with HG (30 mM), and mice were injected with streptozotocin. The levels of intracellular and mitochondrial reactive oxygen species (ROS) were assessed by dihydroethidium staining and MitoSox staining. The cell apoptosis was assessed by flow cytometry and TUNEL staining. Levels of serum creatinine, blood urea nitrogen (BUN), Urinary ACR, and oxidative stress marker 8-hydroxy-2'-deoxyguanosine (8-OHdG) were detected by relevant kits. In addition, fluorescence in situ hybridization staining, RNA-pull down, RNA immunoprecipitation (RIP), co-immunoprecipitation (co-IP), dual-luciferase reporter gene assay and chromatin immunoprecipitation (ChIP) were also executed.

RESULTS

Levels of SOX2OT and silent information regulator 1 (SIRT1) were down-regulated in HG-cultured HK-2 cells. Overexpressing SOX2OT reduced intracellular and mitochondrial ROS levels and cell apoptosis in vitro. Moreover, SOX2OT overexpression also reduced serum creatinine, BUN, urinary ACR, 8-OHdG, renal tubular injury markers KIM1 and NGAL, ROS levels, and cell apoptosis in vivo. In addition, SOX2OT promoted SIRT1 expression by suppressing its ubiquitination. Besides, interference with SIRT1 reversed the inhibitory effect of SOX2OT overexpression on HG-induced oxidative stress and apoptosis. Forkhead box A2 (Foxa2) levels were up-regulated in HG-cultured HK-2 cells. Foxa2 could bind to the SOX2OT promoter and suppress its expression. Furthermore, interfering with SOX2OT reversed the inhibitory effect of Foxa2 interference on HG-induced oxidative stress and apoptosis.

CONCLUSION

Foxa2-mediated SOX2OT up-regulation reduced oxidative stress and apoptosis of RTECs by promoting SIRT1 expression, thus alleviating the progression of DN.

[Treatment Effect of Corncob and Rice Straw Enhanced Subsurface Flow Constructed Wetland on Low C/N Ratio Wastewater]

The lack of carbon sources severely inhibits denitrification in wastewater with a low C/N ratio. Corncob and rice straw were chosen as supplementary carbon sources to bring into the wetland system to supplement the carbon sources needed for denitrification, and the enhancing effects of the two carbon sources on nitrogen removal from the wetland were studied. The cumulative release of carbon was in the order of rice straw[(145.17±9.44) mg·g^-1]>corncob[(57.41±5.04) mg·g^-1] based on the 11-day pure water extraction and release experiment, whereas the cumulative release of nitrogen was in the order of rice straw[(2.31±0.09) mg·g^-1]>corncob[(0.66±0.08) mg·g^-1]. The average carbon/nitrogen ratios released and accumulated by corncob and rice straw during the observation period were 94.78 and 63.64, respectively. Corncob was more suited as an additional carbon source than rice straw. COD concentrations in the effluent from the corncob and straw constructed wetlands were found to be below 50 mg·L^-1 for the 58-day pilot test of subsurface flow constructed wetlands, except on days 8 to 12. The NO₃^--N removal rates of the corncob-added built wetlands were 93%-99% over the observation period, with good denitrification performance. In comparison, the lowest NO₃^--N removal rate of the constructed wetland with the addition of rice straw was only 76.8% at the late stage of operation, and the denitrification rate dropped dramatically. The control group removal rates of NO₃^--N were only 76.2%-77.7%, indicating a clear lack of carbon sources. The accumulation of NO₂^--N was also induced by a lack of carbon supply. NO₂^--N effluent concentrations were 2.5-6 times and 6-26 times higher in the constructed wetlands with rice straw and the control groups, respectively, than those in the wetlands constructed with corncob. The addition of corncob resulted in a more substantial reduction in NO₂^--N content in the constructed wetland than the addition of rice straw (P<0.05). The TN removal rates of wetlands constructed with corncob and rice straw and the control group were 83.75%-93.49%, 76.59%-78.85%, and 67.85%-72.56%, respectively, with significant differences among the three (P<0.01). Finally, pretreatment with dilute alkali heating raised the cumulative carbon release of corncob to (93.73±17.49) mg·g^-1 and the carbon/nitrogen ratio to 175.8, significantly improving the carbon release performance of corncob and demonstrating that it is a suitable source of extra carbon.

A small molecule targeting ALOX12-ACC1 ameliorates nonalcoholic steatohepatitis in mice and macaques

[Figure: see text].

Multiple omics study identifies an interspecies conserved driver for nonalcoholic steatohepatitis

[Figure: see text].

[Viral pathogenic spectrum analysis of severe acute respiratory infection cases in Luohe City, Henan province from 2017 to 2019]

Objective: The purpose of this study was to investigate the characteristics of viral pathogen spectrum and the epidemiological characteristics of each viral pathogen in hospitalized cases associated with severe acute respiratory infection (SARI) in Luohe City, Henan Province from 2017 to 2019. Methods: Based the SARI Case Surveillance Platform, SARI cases were collected in Central Hospital of Luohe City, Henan Province from November 2017 to February 2019. In the end, 783 SARI cases were included, whose throat swabs were taken within 24 h of admission, as well as their demographic characteristics, onset time, clinical characteristics and other information recorded. At the same time, viral identification was performed, and the age and time distribution of each virus were analyzed. Results: The age of 783 SARI cases shown as M (P₂₅, P₇₅) was 3 (1, 5) years old, ranging from 1 month to 95 years old. Children under 5 years old were the majority (71.01%). The males (61.81%) were more than females (38.18%). Among the 783 SARI cases, a total of 9 kind of viruses were identified with 64.88% (508/783) of the throat swabs tested positive for at least one virus. The positive rate of influenza virus and human respiratory syncytial virus were both 20.18% (158 cases), which was the highest among all the detected respiratory virus. The co-infection rate was 15.84% (124/783), among which double infection was the most common, accounting for 85.48% (106/124) of the co-infected cases. And human respiratory syncytial virus, human rhinovirus and influenza virus were the most common pathogen in co-infection cases. Moreover, the viral positive rate was 68.71% in children aged 5 years and 63.27% in people aged 60-95 years. Influenza and human respiratory syncytial virus dominated in winter and spring, while human parainfluenza virus was the main infection in summer. Conclusion: Influenza virus and human respiratory syncytial virus were the main viruses in throat swabs of SARI cases from 2017 to 2019 in Luohe City, Henan Province. There were differences in the age and seasonal epidemiological characteristics of each virus.

TMBIM1 is an inhibitor of adipogenesis and its depletion promotes adipocyte hyperplasia and improves obesity-related metabolic disease

Obesity is characterized by the excessive accumulation of the white adipose tissue (WAT), but healthy expansion of WAT via adipocyte hyperplasia can offset the negative metabolic effects of obesity. Thus, identification of novel adipogenesis regulators that promote hyperplasia may lead to effective therapies for obesity-induced metabolic disorders. Using transcriptomic approaches, we identified transmembrane BAX inhibitor motif-containing 1 (TMBIM1) as an inhibitor of adipogenesis. Gain or loss of function of TMBIM1 in preadipocytes inhibited or promoted adipogenesis, respectively. In vivo, in response to caloric excess, adipocyte precursor (AP)-specific Tmbim1 knockout (KO) mice displayed WAT hyperplasia and improved systemic metabolic health, while overexpression of Tmbim1 in transgenic mice showed the opposite effects. Moreover, mature adipocyte-specific Tmbim1 KO did not affect WAT cellularity or nutrient homeostasis. Mechanistically, TMBIM1 binds to and promotes the autoubiquitination and degradation of NEDD4, which is an E3 ligase that stabilizes PPARγ. Our data show that TMBIM1 is a potent repressor of adipogenesis and a potential therapeutic target for obesity-related metabolic disease.

[Effect of Ferric-carbon Micro-electrolysis on Greenhouse Gas Emissions from Constructed Wetlands]

As the problem of global warming becomes increasingly serious, the greenhouse gas (GHG) emission reduction measures of constructed wetlands (CWs) have drawn significant attention. Ferric-carbon micro-electrolysis exhibits an excellent effect on wastewater purification as well as the potential to reduce GHG emissions. Therefore, to explore the impact of ferric-carbon micro-electrolysis on GHG emissions from intermittent aeration constructed wetlands, four kinds of different wetlands with different fillers were constructed. The four fillers were ferric-carbon micro-electrolysis filler+gravel (CW-Ⅰ), ferric-carbon micro-electrolysis filler+zeolite (CW-Ⅱ), zeolite (CW-Ⅲ), and gravel (CW-Ⅳ). Intermittent aeration technology was used to aerate the wetland systems. The results show that ferric-carbon micro-electrolysis significantly improved the nitrogen removal efficiency of the intermittent aeration constructed wetlands and reduced GHG emissions. Compared with CW-Ⅳ, the CH₄ fluxes of CW-Ⅰ, CW-Ⅱ, and CW-Ⅲ decreased by 32.81% (P<0.05), 52.66% (P<0.05), and 54.50% (P<0.05), respectively. Among them, zeolite exhibited a stronger reduction effect on CH₄ emissions in both the aeration and non-aeration sections. The ferric-carbon micro-electrolysis substantially reduced N₂O emissions. In comparison with CW-Ⅳ, CW-, and CW-Ⅱ achieved N₂O emission reduction by 30.29%-60.63% (P<0.05) and 43.10%-73.87% (P<0.05), respectively. During a typical hydraulic retention period, the comprehensive GWP caused by CH₄ and N₂O emitted by each group of wetland system are (85.21±6.48), (49.24±3.52), (127.97±11.44), and (137.13±11.45) g·m^-2, respectively. The combined use of ferric-carbon micro-electrolysis and zeolite effectively reduces GHG emissions in constructed wetlands. Overall, ferric-carbon micro-electrolysis combined with zeolite (CW-Ⅱ) can be regarded as one of the valuable filler combination methods for constructed wetlands, which can ensure high removal efficiency of pollutants and effective GHG emission reduction in constructed wetlands.

[Effect of Plastic Film Mulching on Methane and Nitrous Oxide Emissions from the Ridges and Furrows of a Vegetable Field]

Investigate the effects of plastic film mulching on CH₄ and N₂O emissions from a vegetable field, a one-year in situ field observation was conducted using a static opaque chamber in a pepper-radish cropping system at the Key Field Station for Monitoring of Eco-Environment of Purple Soil of the Ministry of Agriculture of China at Southwest University, Chongqing. Two treatments (conventional and film mulching) were used to study the influence of film mulching on CH₄ and N₂O emissions. The results showed that mulching significantly increased the annual average soil pH (P<0.01), annual surface and subsurface (5 cm) temperature (P<0.05), and soil moisture content during the radish-growing season (P<0.05). The mulching also significantly reduced CH₄ emissions in the field ridges (P<0.05); the average CH₄ flux from ridges during the pepper-growing season was 0.110 mg·(m²·h)^-1 and 0.028 mg·(m²·h)^-1, and 0.011 mg·(m²·h)^-1 and -0.019 mg·(m²·h)^-1 during the radish-growing season, under the conventional and film mulching treatments, respectively. However, across the entire experiment, CH₄ flux from field furrows was not significantly different between the two mulching treatments (P>0.05), with mean flux values during the pepper-growing season of 0.058 mg·(m²·h)^-1 and 0.057 mg·(m²·h)^-1, and 0.083 mg·(m²·h)^-1 and 0.092 mg·(m²·h)^-1 during the radish-growing season, for conventional and plastic film mulching, respectively. Except for the conventional treatment during the pepper-growing season, CH₄ emissions from ridges were significantly higher than from furrows, but for other treatments, including conventional and film mulching treatments during radish-growing season and film mulching treatment during the pepper-growing season, the CH₄ emissions from furrows were all significantly higher than those from ridges. This was related to the stable anoxic environment created in furrows under high rainfall conditions in Southwest China. The N₂O emission flux from the ridges during the pepper-growing season was 65.41 μg·(m²·h)^-1 and 68.39 μg·(m²·h)^-1 under the conventional and film mulching treatments, respectively, and the N₂O emission flux during the radish-growing season was 78.43 μg·(m²·h)^-1 and 66.19 μg·(m²·h)^-1, respectively. The N₂O flux between conventional treatment and film mulching treatment in ridges or furrows were not significantly different (P>0.05), while the N₂O emissions from the ridges were significantly higher than that from the furrows. CH₄ emission flux was significantly positively correlated with surface and subsurface temperature, while N₂O emission flux was only significantly positively correlated with alkaline nitrogen and ammonium nitrogen content.

Comparative population genomics reveals genetic divergence and selection in lotus, Nelumbo nucifera

Background

Lotus (Nelumbo nucifera) is an aquatic plant with important agronomic, horticulture, art and religion values. It was the basal eudicot species occupying a critical phylogenetic position in flowering plants. After the domestication for thousands of years, lotus has differentiated into three cultivated types -flower lotus, seed lotus and rhizome lotus. Although the phenotypic and genetic differentiations based on molecular markers have been reported, the variation on whole-genome level among the different lotus types is still ambiguous.

Results

In order to reveal the evolution and domestication characteristics of lotus, a total of 69 lotus accessions were selected, including 45 cultivated accessions, 22 wild sacred lotus accessions, and 2 wild American lotus accessions. With Illumina technology, the genomes of these lotus accessions were resequenced to > 13× raw data coverage. On the basis of these genomic data, 25 million single-nucleotide polymorphisms (SNPs) were identified in lotus. Population analysis showed that the rhizome and seed lotus were monophyletic and genetically homogeneous, whereas the flower lotus was biphyletic and genetically heterogeneous. Using population SNP data, we identified 1214 selected regions in seed lotus, 95 in rhizome lotus, and 37 in flower lotus. Some of the genes in these regions contributed to the essential domestication traits of lotus. The selected genes of seed lotus mainly affected lotus seed weight, size and nutritional quality. While the selected genes were responsible for insect resistance, antibacterial immunity and freezing and heat stress resistance in flower lotus, and improved the size of rhizome in rhizome lotus, respectively.

Conclusions

The genome differentiation and a set of domestication genes were identified from three types of cultivated lotus- flower lotus, seed lotus and rhizome lotus, respectively. Among cultivated lotus, flower lotus showed the greatest variation. The domestication genes may show agronomic importance via enhancing insect resistance, improving seed weight and size, or regulating lotus rhizome size. The domestication history of lotus enhances our knowledge of perennial aquatic crop evolution, and the obtained dataset provides a basis for future genomics-enabled breeding.

Vagal Nerve Stimulation Attenuates Ischemia-Reperfusion Induced Retina Dysfunction in Acute Ocular Hypertension

Purpose: The present study aimed to investigate whether cervical vagal nerve stimulation (VNS) could prevent retinal ganglion cell (RGC) loss and retinal dysfunction after ischemia/reperfusion (I/R) injury.

Methods: First, rats were randomly divided into sham group (n = 4) and VNS group (n = 12). Activation of the nodose ganglia (NOG), nucleus of the solitary tract (NTS), superior salivatory nucleus (SSN), and pterygopalatine ganglion (PPG) neural circuit were evaluated by c-fos expression at 0 h after sham VNS and at 0 h (n = 4), 6 h (n = 4), 72 h (n = 4) after VNS. Secondly, rats were randomly assigned to I/R group (pressure-induced retinal ischemia for 1 h and reperfusion for 1 h in the right eye, n = 16) and I/R+VNS group (right cervical VNS for 2 h during the I/R period, n = 16). The left eye of each rat served as a control. Electroretinogram (ERG), RGC numbers, tumor necrosis factor-α (TNF-α) and vasoactive intestinal polypeptide (VIP) levels in retina were determined. Additionally, the level of VIP in PPG was evaluated.

Results: In the first part of the study, compared with the sham group, the VNS group exhibited significantly increased expression of c-fos in NOG, NTS, SSN, and PPG tissues at 0, 6, and 72 h. In the second part of the study, compared with left eyes, retinal function in right eyes (as assessed by the a-wave, b-wave and the oscillatory potential amplitudes of ERG and RGC data) was significantly decreased by I/R. The decreased retinal function was attenuated by VNS. In addition, I/R induced an increase in inflammation, which was reflected by elevated TNF-α expression in the retina. VNS significantly attenuated the increase in I/R-induced inflammation. Moreover, VIP expression in the retina and PPG, which may contribute to the inhibition of the inflammatory response, was significantly increased after VNS.

Conclusion: VNS could protect against retinal I/R injury by downregulating TNF-α. Upregulation of VIP expression due to activation of the NOG-NTS-SSN-PPG neural circuit may underlie to the protective effects of VNS.

[Relationships between serum cystatin C, chemerin levels and subclinical atherosclerosis in type 2 diabetes mellitus patients]

Objective: To investigate the relationships between serum cystatin C (Cys C), chemerin levels and subclinical atherosclerosis in type 2 diabetes mellitus (T2DM) patients. Methods: A cross-sectional study was carried out between January 2016 and January 2018, and T2DM patients with carotid intima-media thickness (IMT) less than 1.1 mm were selected as subjects (100 males and 80 females, aged 40-60 years). The brachial-ankle pulse wave velocity (baPWV) ≥ 1 700 cm/s was set as the observation group (subclinical atherosclerosis) and baPWV<1 700 cm/s as the control group (non-subclinical atherosclerosis). Physical and blood examination were performed in both groups. Serum Cys C and chemerin levels were measured and their relationship with subclinical atherosclerosis was analyzed. Results: There was a statistically significant correlation between serum creatinine (r=0.167, P=0.011) and baPWV in the observation group, but not in the control group (r=0.105, P=0.070). Multiple linear regression analysis showed that age, duration of diabetes, serum creatinine, estimated glomerular filtration rate (eGFR), Cys C and chemerin were independently associated with baPWV, while high sensitive C reactive protein (hsCRP) and glycosylated hemoglobin (HbA1c) were not associated with baPWV. The elevation of serum Cys C (β'=0.393, P=0.003) and chemokine (β'=0.340, P=0.007) were correlative factors for atherosclerosis. Conclusion: The level of serum Cys C and chemerin is possibly related to the occurrence and development of subclinical atherosclerosis in T2DM patients.

Exploring the Mechanisms of Electroacupuncture-Induced Analgesia through RNA Sequencing of the Periaqueductal Gray

Electroacupuncture (EA) can relieve various pains. However, its mechanism in terms of the transcriptome is still not well-known. To explore the full profile of EA-induced molecular modification in the central nerve system, three twins of goats were selected for a match-paired experiment: EA stimulation (60 Hz, 30 min) and none-EA (control). Goats in the EA group showed an increased (p < 0.05) nociceptive threshold compared with the control goats. Experimental goats were sacrificed at 4 h of the experiment, and the periaqueductal grays were harvested for RNA sequencing. As a result, 2651 differentially expressed genes (1803 up-regulated and 848 down-regulated genes) were found and enriched in 30 Kyoto Encyclopedia of Genes and Genomes pathways and 149 gene ontology terms. EA-regulated five neuropeptide genes (proenkephalin, proopiomelanocortin, preprodynorphin, diazepam-binding inhibitor and proprotein convertase 1 inhibitor) were validated with quantitative PCR. Furthermore, up-regulated glutamate receptors, glutamate transporters, γ-aminobutyric acid (GABA) receptors, GABA transporters, synaptotagmins or mitogen-activated protein kinase (MAPK) genes might contribute to EA-induced analgesia through regulating the glutamatergic synapse, GABAergic synapse, MAPKs, ribosome or ubiquitin-proteasome pathways. Our findings reveal a full profile of molecular modification in response to EA and provide a solid experimental framework for exploring the mechanisms underlying EA-induced analgesia.

Activated natural killer cells accelerate liver damage in patients with chronic hepatitis B virus infection

Emerging evidence indicates that natural killer (NK) cells may contribute to liver injury in patients with hepatitis B virus (HBV) infection. Because HBV infection progresses through various disease phases, the cytolytic profiles of peripheral and intrahepatic NK cells in HBV-infected patients remain to be defined. In this study, we comprehensively characterized intrahepatic and peripheral NK cells in a cohort of HBV-infected individuals, and investigated their impact on liver pathogenesis during chronic HBV infection. The study population included 34 immune-clearance (IC) patients, 36 immune-tolerant (IT) carriers and 10 healthy subjects. We found that the activity of peripheral NK cells from IC patients was functionally elevated compared to IT carriers and controls, and NK cell activation was indicated by an increased expression of CD69, CD107a, interferon (IFN)-γ and tumour necrosis factor (TNF)-α. Further analysis showed that the increased activity of both peripheral and hepatic NK cells was correlated positively with liver injury, which was assessed by serum alanine aminotransferase levels (ALT) and the liver histological activity index (HAI). Interestingly, the frequency of peripheral NK cells was reduced in IC patients (especially those with higher HAI scores of 3-4), but there was a concomitant increase in hepatic NK cells. The functionally activated NK cells are enriched preferentially in the livers of IC patients and skew towards cytolytic activity that accelerates liver injury in chronic hepatitis B (CHB) patients.

Zoledronate inhibits phosphate and bone morphogenetic protein 2-induced extracellular calcification of vascular smooth muscle cells in vitro

The aim of this study was to explore the effects of the bisphosphonate zoledronate on calcification induced by inorganic phosphate (Pi) and/or bone morphogenetic protein 2 (BMP-2) and the underlying mechanisms. Primary vascular smooth muscle cells (VSMCs) from rats were treated with 3 mM Pi or 3 mM Pi/BMP-2, with and without addition of zoledronate; 1.4 mM Pi served as a control. Calcium deposits, expression of core binding factor α-1 (Cbfa-1), osteopontin (OPN), parathyroid pituitary-specific transcription factor (Pit)-1 and Pit-2, and Pi uptake of VSMCs was determined. The calcification of VSMCs induced by elevated Pi or Pi/BMP-2 was significantly inhibited by zoledronate. The expression of Cbfa-1, OPN and Pit-1 was increased significantly after treatment with an elevated level of Pi or Pi/BMP-2, and this expression was significantly suppressed by addition of zoledronate. Pi uptake of VSMCs increased following treatment with elevated Pi and significantly decreased by addition of zoledronate. These results indicated that zoledronate effectively inhibited calcification induced by Pi/BMP-2, and this may have been achieved by means of the downregulation of expression of calcification-related proteins and uptake of Pi.

Induction of oxidative DNA damage in human foreskin fibroblast Hs68 cells by oxidized beta-Carotene and lycopene

Two recent clinical trials suggest that beta-carotene may be harmful to smokers. In this study we examined the hypothesis that beta-carotene may become toxic when degradation occurs. beta-Carotene (BC) and lycopene (LP) with or without prior heat treatment (60 degrees C for 1 h in open air) were incubated at 20 and 40 microM with calf thymus DNA or human fibroblasts Hs68 cells. The heat treatment resulted in ca. 80% and 35% bleaching of BC and LP, respectively. When Hs68 cells were incubated with the oxidized beta-carotene (OBC) or oxidized lycopene (OLP) at 37 degrees C for 20 h, cell viability was significantly and dose-dependently decreased whereas cell viability was not affected by BC or LP. Cell death, which was already evident at 4 h after incubation with OBC or OLP, was possibly attributable to apoptosis, as shown by the increased histone-associated DNA fragmentation. However, cell lysis, measured as release of lactate dehydrogenase, also occurred at 4 h after incubation with OBC and OLP, although the extent was relatively small and was greater for OLP than for OBC. When calf thymus DNA was incubated with OBC or OLP at 37 degrees C for 20 h, the 8-hydroxy-2-deoxyguanosine (8-OH-dG) level was significantly and dose-dependently increased by OLP whereas the increase by OBC was only significant at 40 microM. When Hs68 cells were incubated with OBC and OLP for 20 h, both compounds increased the 8-OH-dG level, but the effect was only significant for 40 microM OLP. Comet (single-cell gel electrophoresis) assay of DNA damage in Hs68 cells was determined at 2 h after incubation with OBC or OLP because of its high sensitivity. Both OBC and OLP significantly and dose-dependently increased DNA breakage while BC and LP had no effect. Inclusion of BHT during incubation of cells with 40 microM OBC or OLP partially inhibited (ca. 40%, p < .05) the extent of comet formation. Intriguingly, OBC and OLP neither induce lipid peroxidation in Hs68 cells (measured as thiobarbituric acid-reactive substances released into the medium) nor increased the intracellular level of reactive oxygen species. Although it is presently unclear about what degradation products are formed, this study has demonstrated that, when oxidized, BC and LP lead to oxidative damage to both purified DNA and cellular DNA. The results suggest that such damage may contribute to the adverse effects of beta-carotene reported in recent clinical studies and caution that it is important to prevent oxidation of BC and LP for human uses such as in supplemental studies.

DHEA inhibits cell growth and induces apoptosis in BV-2 cells and the effects are inversely associated with glucose concentration in the medium

Dehydroepiandrosterone (DHEA), a major steroid secreted by the adrenal gland which decreases with age after adolescence, is available as a nutritional supplement. DHEA is known to have antiproliferative effects but the mechanism is unclear. In this study using BV-2 cells, a murine microglial cell line, we investigated the effect of DHEA on cell viability and the interaction between DHEA and glucose concentrations in the medium. We showed that DHEA inhibited cell viability and G6PD activity in a dose-dependent manner and that the effect of DHEA on cell viability was inversely associated with glucose concentrations in the medium, i.e. lowered glucose strongly enhanced the inhibition of cell viability by DHEA. DHEA inhibited cell growth by causing cell cycle arrest primarily in the G0--G1 phase, and the effect was more pronounced at zero glucose (no glucose added, G0) than high glucose (4.5 mg/ml of the medium, G4.5). Glucose deprivation also enhanced apoptosis induced by DHEA. At G4.5, DHEA did not induce formation of DNA ladder until it reached 200 microM. However, at G0, 100 microM DHEA was able to induce apoptosis, as evidenced by the formation of DNA ladder, elevation of histone-associated DNA fragmentation and increase in cells positively stained with annexin V-FITC and annexin V-FITC/propidium iodide. The interactions between DHEA and glucose support the contention that DHEA exerts its antiproliferative effects through alteration of glucose metabolism, possibly by inhibition of G6PD activity leading to decreased supply of ribose-5-phosphate for synthesis of DNA and RNA. Although DHEA is only antiproliferative at pharmacological levels, our results indicate that its antiproliferative effect can be enhanced by limiting the supply of glucose such as by energy restriction. In addition, the present study shows that glucose concentration is an important factor to consider when studying the antiproliferative and toxicological effects of DHEA.

Total plasma malondialdehyde levels in 16 Taiwanese college students determined by various thiobarbituric acid tests and an improved high-performance liquid chromatography-based method

OBJECTIVES

In determining the plasma malondialdehyde MDA levels in some Taiwanese college students, we found rather different results by using different thiobarbituric acid TBA tests, even by the high-performance liquid chromatography HPLC-based methods. Here, we re-evaluated four commonly used TBA tests and improved the HPLC-based test.

DESIGN AND METHODS

We used the blood plasma of 16 college volunteers to determine plasma MDA by using four methods: a spectrophotometric measurement of thiobarbituric acid-reactive substances (TBARS) in the TCA-supernatant of plasma (Method A); a fluorescence measurement of plasma lipid peroxides (Method B); and two different HPLC-based measurements of MDA with either 532-nm measurement (Method C, HPLC/532 nm) or fluorescence measurement (Method D, HPLC/fluor.).

RESULTS

The levels of MDA or TBA reactive substances obtained from the four methods differed substantially (0.39 +/- 0.15; 2.14 +/- 0.73; 0.75 +/- 0.22; and 0.38 +/- 0.15 microM for Methods A, B, C, and D, respectively). The results were positively correlated between Methods A and B (r = 0.740, p < 0.02) and between Methods C and D (r = 0.516, p < 0.05). However, results were negatively correlated between Methods B and D (r = -0.548, p < 0.05). Because most plasma MDA is bound to proteins, we modified the HPLC-based methods (C and D) by adding an alkaline hydrolysis step, and the plasma TBA-MDA adduct detected by HPLC/532 nm was referred to as total MDA. RESULTS show that alkaline hydrolysis was a critical step for measurement of total MDA in plasma because this treatment led to release of MDA from plasma proteins. We also adapted the potassium iodide (KI) treatment of plasma from Method D to reduce lipid hydroperoxides. Our modified method gave a total MDA level in the 16 volunteers of approximately 1.5 microM, which was equal to protein-bound MDA plus free MDA. This total MDA level was positively (p < 0.05) correlated with the level of TBA reactive substances obtained from Methods C (r = 0.63, p < 0.05) and D (r = 0.48, p < 0.07), but was not correlated with those from Methods A and B. The recovery (84 approximately 105%), precision (within-assay coefficient of variation: 2.4%, between-assay coefficient of variation: 4 approximately 8%) and sensitivity of the modified procedure were comparable to other HPLC-based methods.

CONCLUSION

By using a validated modification of HPLC-based TBA method, the total plasma MDA in 16 Taiwanese college students was found to be 1.54 microM, which was relatively high compared to those obtained by other HPLC-based method, primarily due to the release of protein-bound MDA by alkaline hydrolysis. This level equaled the sum of protein-bound MDA and free MDA in plasma, confirming that this level represents total plasma MDA.

Use of rat liver slices for the study of oxidative DNA damage in comparison with isolated rat liver nuclei and HepG2 human hepatoma cells

Tissue slices are a useful biological system for lipid peroxidation studies but their use for DNA damage studies is not well characterized. Hence, the present study investigates DNA damage in rat liver slices, in comparison with isolated rat liver nuclei and HepG2 human hepatoma cells, incubated with ferric nitrilotriacetate (Fe(III)-NTA), bromotrichloromethane (BrCCl(3)), bromobenzene (BrB) or 2-nitropropane (2-NP) at 37 degrees C for 2 hr. DNA damage was measured in slices, cells or nuclei after centrifugation as formation of as 8-hydroxy-2'-deoxyguanosine (8-OH-dGu) and loss of double-stranded (dsDNA) due to strand breakage using a fluorometric analysis of DNA unwinding (FADU). Lipid peroxidation was measured as thiobarbituric acid-reactive substances (TBARS) released into the medium. The results show that in liver slices and isolated nuclei, Fe/NTA (1 mM/4 mM) induced high levels of TBARS but low levels of 8-OH-dGu, whereas the oxidant induced low levels of TBARS and no formation of 8-OH-dGu in HepG2 cells. In all three systems, inclusion of ascorbate caused dose-dependent formation of 8-OH-dGu, and the levels were similar between liver slices and HepG2 cells but were far higher in isolated nuclei. In liver slices the FADU assay was not applicable due to limited solubilization of DNA from the slice, whereas the assay detected significant loss of dsDNA in HepG2 cells and slight loss in isolated nuclei induced by Fe/NTA with or without ascorbate. Liver slices incubated with 1 mm BrCCl(3), BrB or 2-NP had elevated TBARS but had little or no formation of 8-OH-dGu; none of these oxidants induced lipid peroxidation or DNA damage in HepG2 cells. When liver slices obtained from rats injected with diethylmaleate (to deplete GSH) were incubated with BrCCl(3), BrB or 2-NP, levels of TBARS and 8-OH-dGu increased markedly. Similarly, HepG2 cells with decreased GSH showed marked elevation of TBARS and loss of dsDNA induced by these oxidants, although no formation of 8-OH-dGu was detected. The present study demonstrates the usefulness and limitations of liver slices for DNA damage studies and the importance of cellular GSH in the protection of DNA against environmental toxicants.

Toxicological and antioxidant effects of short-term dehydroepiandrosterone injection in young rats fed diets deficient or adequate in vitamin E

This study examined the in vivo antioxidant and/or prooxidant effect of short-term dehydroepiandrosterone (DHEA) injection and the effect of dietary vitamin E. Male Sprague-Dawley rats (4 wk old) were fed vitamin E-deficient or vitamin E-adequate (30 mg DL-alpha-tocopheryl acetate/kg) diet for 4 weeks followed by intraperitoneal injection of DHEA for 1 week. The results showed that DHEA injection caused a dose-dependent decrease in body weight, and this effect was more pronounced in vitamin E-deficient rats. In contrast, DHEA injection significantly increased liver, kidney and adrenal weights. Hepatic vitamin E content was significantly lowered by vitamin E deficiency, which led to significantly increased ex vivo and iron-induced lipid peroxidation. DHEA injection did not affect hepatic vitamin E content but significantly decreased ex vivo and iron-induced lipid peroxidation in vitamin E-deficient rats. Hepatic total sulfhydryl (SH) groups and non-protein SH contents were not affected by vitamin E but were significantly increased by DHEA injection, which at 100 mg/kg was not more effective than at 50 mg/kg. Hepatic glutathione S-transferase (GST) activity was significantly decreased by DHEA, but vitamin E alleviated such a decrease. DHEA injection significantly increased hepatic glucose 6-phosphate dehydrogenase (G6PD) activity, and the effect was dose dependent in vitamin E-deficient rats. Thus, DHEA may compensate for vitamin E deficiency in vivo, and this effect is masked when dietary vitamin E is adequate. The antioxidant effect of DHEA is accompanied by decreased body weights, enlarged (fat-laden) tissues and altered activities of hepatic GST and G6PD.

Elevated lipid peroxidation and disturbed antioxidant enzyme activities in plasma and erythrocytes of patients with uterine cervicitis and myoma

OBJECTIVES

We investigated whether oxidative stress is associated with human uterine cervicitis and uterine myoma.

DESIGN AND METHODS

We measured lipid peroxidation and antioxidant enzymes in plasma and erythrocytes of cervicitis patients and myoma patients in comparison with matched controls. Thiobarbituric acid-reactive substances (TBARS), a measure of lipid peroxidation, were determined in plasma; glutathione peroxidase (GSHPx) and catalase in erythrocytes; and superoxide dismutase (SOD) in both plasma and erythrocytes.

RESULTS

We showed that plasma TBARS were significantly higher (p < 0.05) in both cervicitis patients and myoma patients than in controls. Plasma TBARS were significantly (and negatively) correlated with plasma and erythrocyte T-SOD activities in cervicitis patients only. Plasma T-SOD activity was significantly lower in both groups of patients than in controls whereas erythrocyte T-SOD activity was only significantly lower in myoma patients. The lowered plasma T-SOD activity in the cervicitis patients was attributed to decreased Mn-SOD activity whereas the lowered plasma T-SOD activity in myoma patients was attributed to decreased activities of both Cu,Zn-SOD and Mn-SOD. Erythrocyte GSHPx activity was 14% higher (p < 0.05) in cervicitis patients and 11% lower (p > 0.05) in myoma patients than in controls; catalase activity was 10% higher (p > 0.05) in cervicitis patients and 13% lower (p > 0.05) in myoma patients than in controls. Neither erythrocyte GSHPx nor catalase activity was significantly correlated with plasma TBARS.

CONCLUSIONS

The elevated lipid peroxidation and disturbed antioxidant enzyme activities demonstrate the potential of oxidative injury in patients with uterine cervicitis and myoma.

UVA-induced oxidative damage to rat liver nuclei: reduction of iron ions and the relationship between lipid peroxidation and DNA damage

Lipid peroxidation and DNA damage and the relationship between the two events were studied in rat liver nuclei irradiated with low dose UVA. Lipid peroxidation was measured as thiobarbituric acid-reactive substances (TBARS) by spectrophotometric method and as malondialdehyde-TBA adduct by HPLC, and DNA damage was measured as 8-hydroxy-deoxyguanosine (8-OH-dGu) and strand breakage (or loss of double-stranded DNA) by a fluorometric analysis of alkaline DNA unwinding method. The results show that UVA irradiation by itself increased nuclear lipid peroxidation but caused little or no DNA strand breakage or 8-OH-dGu. When 0.5 mM ferric (Fe+3) or ferrous (Fe+2) ions were added to the nuclei during UVA irradiation, lipid peroxidation and DNA damage, measured both as 8-OH-dGu and loss of double-stranded DNA, were strongly enhanced. Lipid peroxidation occurred concurrently with the appearance of 8-OH-dGu. Fe3+ ions were reduced to Fe2+ in this UVA/Fe2+/nuclei system. Lipid peroxidation and DNA damage were neither inhibited by scavengers of hydroxyl radical and singlet oxygen nor inhibited by superoxide dismutase and catalase. Inclusion of EDTA or chain-breaking antioxidants, butylated hydroxytoluene (BHT) and diphenylamine (an alkoxy radical scavenger), inhibited lipid peroxidation but not the level of 8-OH-dGu. BHT also did not inhibit the loss of double-stranded DNA in this system. This study demonstrates the reduction of exogenous Fe+3 by UVA when added to rat liver nuclei, and, as a result, oxidative damage is strongly enhanced. In addition, the results show that DNA damage is not a result of lipid peroxidation in this UVA/Fe2+/nuclei system.

Reaction of cyclohexylamine with hypochlorite and enhancement of oxidation of plasma sulfhydryl groups by hypochlorite in vitro

In this study we investigated the reaction of cyclamate and its major metabolite, cyclohexylamine (CyhNH2), with NaOCl. NaOCl at 100 microM was allowed to react with various concentrations of cyclamate and CyhNH2, and the reactivity was compared with those of reduced glutathione (GSH) and ascorbic acid. The results showed that CyhNH2 was less reactive with NaOCl than GSH but was slightly more reactive than ascorbic acid at concentrations below 50 microM. CyhNH2 at 75 and 100 microM did not further decrease NaOCl. Cyclamate was much less reactive than CyhNH2, with only 43% loss in NaOCl at 100 microM cyclamate. When human blood plasma was incubated with 0.75 microM NaOCl, inclusion of CyhNH2 enhanced oxidation of sulfhydryl groups in a concentration-dependent manner, with complete oxidation of SH groups at 7.5 mM CyhNH2. Cyclamate had no effect. This enhancement by CyhNH2 suggests the formation of reactive products from the reaction of CyhNH2 with NaOCl. Absorption spectra demonstrated that reaction of CyhNH2 with NaOCl at pH 7.4 produced N-monochloramine, as evidenced by the appearance of a new peak at 245 nm and by the disappearance of the 292-nm peak of NaOCl. Cyclamate, which contains a sulfamic acid instead of a primary amine, also reacted with NaOCl at pH 7.4, but the reaction was much less pronounced and the product was probably not monochloramine since the peak was at 270 nm rather than at 245 nm. Because cyclamate is an important sweetener in many countries for people with diabetes mellitus, the possibility exists that CyhNH2 may enhance oxidation of important proteins by HOCl/OCl-.

Plasma levels of antioxidant vitamins, selenium, total sulfhydryl groups and oxidative products in ischemic-stroke patients as compared to matched controls in Taiwan

The possible involvement of oxidative damage and antioxidant protection has been suggested in the pathogenesis of stroke which is the second-leading cause of death in Taiwan. In this study we investigated the relationship between ischemic stroke and plasma status of antioxidants and oxidative products. Plasma levels of vitamin A, alpha-tocopherol, carotenoids, selenium (Se), total SH groups (T-SH), thiobarbituric acid-reactive substances (TBARS) and protein carbonyl, a marker of protein damage, were determined in ischemic-stroke patients (n = 36, blood sampled within 24 hrs after the clinical event) in comparison with 21 matched controls. The cholesterol-adjusted carotenoids and vitamin E were significantly lower (P < 0.05) in the plasma of ischemic-stroke patients than those of the controls. TBARS were higher (P < 0.05) in the patients than in the controls but Se, T-SH and protein carbonyls were not significantly different between the two groups. Separation of the patients into small-artery ischemic stroke (SAIS, n = 17) and large-artery ischemic stroke (LAIS, n = 19) groups revealed that both carotenoids/cholesterol and vitamin E/cholesterol ratios were significantly lower in both LAIS and SAIS groups than the controls (n = 21) while vitamin A/cholesterol was not different among the three groups. TBARS were only significantly higher in the LAIS group. The results demonstrated that, within 24 hrs after the clinical event, the acute-ischemic stroke patients had lowered levels of cholesterol-adjusted carotenoids and alpha-tocopherol but elevated levels of TBARS in the plasma as compared to the matched controls. It remains to be resolved as to whether enhanced lipid peroxidation is a cause or a result of lowered antioxidants in ischemic stroke.

Hemolytic effects of dehydroepiandrosterone in vitro

Dehydroepiandrosterone (DHEA), a major steroid secreted by the adrenal gland which decreases with age after adolescence, is available as a over-the-counter product. This study demonstrates that DHEA induced lysis of human red blood cells (RBCs) in a concentration-dependent manner, with ca. 70% hemolysis at 2 mM DHEA at 37 degrees C for 1 hr. Hemolysis induced by 2 mM DHEA was rapid and involved neither hemoglobin oxidation nor lipid peroxidation. The hemolysis was also not inhibited by addition of EDTA, catalase, superoxide dismutase, glucose or a radical scavenger including mannitol, dimethylsulfoxide and alpha-tocopherol, indicating a non-oxidative mechanism. RBCs stored overnight before incubation with DHEA were hemolyzed to a lesser extent than the freshly prepared RBCs. Light microscopy of the fresh RBCs following 1-h incubation with 2 mM DHEA revealed thickened and cup-shaped deformity of the membranes, suggesting a change in the membrane structure possibly due to the intercalation of the steroid into the membranes.

Ascorbic acid inhibits lipid peroxidation but enhances DNA damage in rat liver nuclei incubated with iron ions

In this report we studied DNA damage and lipid peroxidation in rat liver nuclei incubated with iron ions for up to 2 hrs in order to examine whether nuclear DNA damage was dependent on membrane lipid peroxidation. Lipid peroxidation was measured as thiobarbituric acid-reactive substances (TBARS) and DNA damage was measured as 8-OH-deoxyguanosine (8-OH-dG). We showed that Fe(II) induced nuclear lipid peroxidation dose-dependently but only the highest concentration (1.0 mM) used induced appreciable 8-OH-dG. Fe(III) up to 1 mM induced minimal lipid peroxidation and negligible amounts of 8-OH-dG. Ascorbic acid enhanced Fe(II)-induced lipid peroxidation at a ratio to Fe(II) of 1:1 but strongly inhibited peroxidation at ratios of 2.5:1 and 5:1. By contrast, ascorbate markedly enhanced DNA damage at all ratios tested and in a concentration-dependent manner. The nuclear DNA damage induced by 1 mM FeSO4/5 mM ascorbic acid was largely inhibited by iron chelators and by dimethylsulphoxide and mannitol, indicating the involvement of OH. Hydrogen peroxide and superoxide anions were also involved, as DNA damage was partially inhibited by catalase and, to a lesser extent, by superoxide dismutase. The chain-breaking antioxidants butylated hydroxytoluene and diphenylamine (an alkoxyl radical scavenger) did not inhibit DNA damage. Hence, this study demonstrated that ascorbic acid enhanced Fe(II)-induced DNA base modification which was not dependent on lipid peroxidation in rat liver nuclei.

Nutritional evaluation of women in urban areas in continental China

In 1993-1995, a nutritional survey was conducted in China, in which 50 women each in three cities of Beijing, Shanghai and Nanning (thus 150 in total) volunteered to offer 24-hr total food duplicates and peripheral blood samples. People daily took 1,776 kcal (7,431 kJ) energy, 57 g protein, 75 g lipid, 218 g carbohydrate, 439 mg calcium, 24 mg iron, 3,398 mg sodium and 1,521 mg potassium. When compared with the recommended dietary allowance for Chinese, intakes of energy, iron and possibly vitamin C were sufficient in a majority of the participants, but not so in cases of calcium, and several vitamins. The lipid energy ratio was 38% on an average and was higher than 30% in a majority (73%) of the people. BMI, but not the lipid energy ratio, correlated with the serum triglyceride level. In accordance with high iron intake, the prevalence of anemia was low. Inter-city differences were evident in nutrient sources. Thus, Beijing people took more amounts of protein and lipid from meats (including eggs and milk), whereas plant-based foods were important sources of lipid in Shanghai and that of protein in Nanning. Furthermore, consumption of rice was significantly lower in Beijing than in Shanghai and Nanning, whereas wheat consumption was higher in Beijing than in Shanghai and Nanning.

UVA-potentiated damage to calf thymus DNA by Fenton reaction system and protection by para-aminobenzoic acid

Calf thymus DNA was irradiated with low-intensity UVA (main output at 365 nm, 2 mW cm-2 or 36 kJ m-2 for 30 min), and the role of metal ions, hydrogen peroxide and reactive oxygen species (ROS) was examined. DNA damage was measured as thiobarbituric acid-reactive substances (possibly from degradation of deoxyribose) and as changes in ethidium bromide-DNA fluorescence due to unwinding from strand breaks. Under the present experimental conditions, UVA alone or in the presence of H2O2 had no effect on DNA but slightly enhanced the damage by iron/EDTA. Ultraviolet A strongly enhanced DNA damage (ca four- to five-fold) by the Fenton reaction system (50 microM Fe2+/100 microM EDTA + 0.5 mM H2O2). The results suggest that the Fenton reaction system was "photosensitized" to damage DNA by low-intensity UVA radiation. The enhanced damage by UVA was attributed in part to the reduction of Fe3+ to Fe2+. Ultraviolet A had no effect when iron (ferric or ferrous) ions were replaced by Cu2+, Zn2+, Mn2+ or Cd2+. The ROS involved in the UVA-enhanced damage to DNA by the Fenton reagents were OH and, to a lesser extent, superoxide anions. The UVA-potentiated DNA damage by the Fenton reaction system was then used to examine the protective effect of para-aminobenzoate (PABA), a UVB-absorbing sunscreen that protects against photocarcinogenesis in hairless mice. The results show that PABA and mannitol dose-dependently inhibited the damage with concentrations required for 50% inhibition at 0.1 mM and 3 mM, respectively. The protection by PABA was attributed to its radical-scavenging ability because PABA does not absorb light in the UVA region. These findings may be relevant to the biological damage by UVA and suggest that PABA is useful in protection against photocarcinogenesis by wide-range UV radiation.

The antioxidant and prooxidant activity of some B vitamins and vitamin-like compounds

The antioxidant and prooxidant properties of some B vitamins (BVIT) and vitamin-like compounds (VLC) that are commonly included in multivitamin preparations were investigated. Microsomal lipid peroxidation induced by FeCl3 and ascorbate was dose-dependently inhibited by pyridoxal and pantothenate but was stimulated by thiamin, pyridoxine and carnitine. Among the compounds tested, only pyridoxine and pyridoxal reacted, but rather poorly, with superoxide anions. All test compounds reacted with .OH with second-order rate constants comparable or higher than that for mannitol, as assayed using deoxyribose oxidation by a system containing EDTA-chelated Fe(III), H2O2 and ascorbate. When assayed in the absence of EDTA, pyridoxal showed increased inhibition of deoxyribose oxidation over that in the presence of EDTA, suggesting a potent ability of pyridoxal to bind and deactivate iron. Pantothenate, pyridoxine and myo-inositol appeared to equally inhibit deoxyribose oxidation both in the presence and absence of EDTA. The lack of inhibition on deoxyribose oxidation in the absence of EDTA by thiamin, carnitine and choline may suggest that the .OH-scavenging ability is equalled by the ability of the scavenger-iron complexes to form .OH or other redox active species. However, stimulation of lipid peroxidation by pyridoxine was unexplained and the effect was not attributed to reduction of Fe(III) to Fe(II). This study shows that the radical-scavenging ability of BVIT and VLC did not correlate with their effects on microsomal lipid peroxidation. Moreover, the stimulation of lipid peroxidation by thiamin, pyridoxine and carnitine suggests that supplementation of large amounts of these compounds may not be desirable.

Some similarities in vascular effects of oleic acid and oxidized low-density lipoproteins on rabbit aorta

In the present study oxidized low-density lipoproteins (ox-LDL) was prepared by a new simple method: oxidizing LDL by electrolysis-generated free radicals. In endothelium-intact norepinephrine(NE)-precontracted rabbit aortic rings, ox-LDL (2 mg protein/ml)-incubation for 30 min or 3 mM oleic acid for 10 min, significantly attenuated the acetylcholine (ACh)-induced endothelium-dependent relaxation (EDR) (both P < 0.01 v control). Such attenuated EDR were sustained after washout. The oleic acid-induced endothelial dysfunction was associated with concomitant reduction of cGMP level in aortic rings. Preincubation of aortic rings with 500 microM L-arginine or 100 u/ml superoxide dismutase for 10 min partly prevented the oleic acid-induced attenuation of EDR and reduction of cGMP, indicating that oleic acid may impair the L-arginine-nitric acid pathway and/or inactivate the nitric oxide. Both ox-LDL and oleic acid potentiated NE-induced aortic ring contraction (both P < 0.01 v control). Such potentiating effects were abolished by preincubation with 1 microM verapamil, indicating the possible involvement of calcium influx in vascular smooth muscle cells during the enhanced contraction. Gas-chromatographic analysis showed that oleic acid content is the highest among all free fatty acids in ox-LDL. In conclusion, we found that oleic acid possesses certain similar vascular effects as ox-LDL in inducing endothelial dysfunction and in enhancing NE-induced vasocontraction in rabbit aortic ring. We proposed that the vasoactive effects of ox-LDL may be resulted partly from the activation or release of active oleic acid molecule during oxidative modification of LDL.

Potentiation of oxidative damage to rat red blood cells by the concurrent presence of t-butyl hydroperoxide and bromotrichloromethane

Recently potentiation of oxidative damage in rat red blood cells (rRBC) incubated with t-butylhydroperoxide (BHP) in combination with bromotrichloromethane (BrCCI3) was demonstrated. The mechanism by which this combination (BrCCI3/BHP) potentiates the oxidative damage to rRBC was investigated in this study. When rRBC were incubated with 0.1 mM BHP, 0.5 mM BrCCI3, or the two combined, BrCCI3/BHP-potentiated lipid peroxidation and hemolysis were further enhanced under anaerobic conditions. However, the potentiation of lipid peroxidation was abolished by heating or trypsin digestion of rRBC. Electron spin resonance (ESR) studies demonstrated an increase of alkoyl radical induced by BrCCI3/BHP in rRBC, and this increase was abolished by heating or predigestion of hemolysates with trypsin. The inhibition of lipid peroxidation by diphenylamine (which reacts with alkoxyl radicals but not peroxyl radicals) suggests an important role of alkoxyl radicals. Overall, the present findings demonstrate that the increase in radical-related oxidative damage, possibly mediated by proteinlike materials, may be at least partially responsible for the potentiation of damage to rRBC induced by BrCCI3/BHP, and perhaps by BrCCI3. Although the in vivo significance of these results remains to be investigated, it seems likely that halocarbon toxicity may be amplified by elevated levels of lipid peroxide in blood.

Interactions of human blood plasma with hydrogen peroxide and hypochlorous acid

Activated neutrophils produce both hydrogen peroxide (H2O2) and hypochlorous acid (HOCl). Previous work has shown that HOCl depletes antioxidants, modifies proteins, and forms fatty acid chlorohydrins but does not cause significant lipid peroxidation in human plasma. Because activated phagocytes have been claimed to stimulate lipid peroxidation in plasma, we examined the effects of H2O2 and HOCl alone and in combination on plasma constituents. Hydrogen peroxide at concentrations below 0.5 mmol/L had little effect, but 1 to 2 mmol/L H2O2 caused loss of ascorbic acid and protein thiol groups, an effect potentiated by preincubation of the plasma with sodium azide to inhibit catalase. H2O2 caused no detectable lipid peroxidation or loss of alpha-tocopherol in plasma, but some depletion of ubiquinol occurred. The combination of HOCl and H2O2 caused more lipid peroxidation than either agent alone. Peroxidation was not inhibited by the metal chelators ethylenediaminetetraacetic acid and deferoxamine or by the singlet O2/hydroxyl radical scavenger histidine. We hypothesize that the phagocyte-derived H2O2 and HOCl could interact in the microenvironment of the activated leukocyte to induce lipid peroxidation of plasma lipoproteins or cell membranes (or both).

Oxidation of biologic molecules by ozone: the effect of pH

Ozone (O3) is a powerfully oxidizing pollutant gas. Its toxic effects to animals appear to be worsened by coexposures to acid-generating compounds such as oxides of nitrogen and sulfur. Ozone (16 ppm) oxidizes ascorbic acid and uric acid (two important antioxidants in lung lining fluids) at equal rates at pH 5.0 or pH 7.4. Loss of intrinsic fluorescence and formation of carbonyls in albumin exposed to O3 are similar at both pH values. However, albumin-SH groups are lost much faster on exposure to O3 at pH 7.4 than at acidic pH values. A similar slower rate of -SH group disappearance at acidic pH is seen when cysteine or reduced glutathione are exposed to O3. We suggest that the ability of reduced glutathione, albumin, and other proteins containing -SH groups to scavenge O3 in the respiratory tract is impaired at low pH and that this effect could contribute to the aggravation of O3 toxicity.

Cigarette smoke oxidation of human plasma constituents

In vitro exposure of fresh human plasma to cigarette smoke (CS) was used as a model for reactions that could be occurring in CS-exposed respiratory tract lining fluids (RTLFs) and lung parenchyma. The central focus of this model was to characterize the consumption of endogenous plasma antioxidants in relationship to the appearance of oxidized proteins and lipids as a consequence of exposure to CS, or to aldehydes present in CS. The amelioration of CS-induced protein and lipid oxidation in plasma by the addition of selective exogenous antioxidants was also assessed. We found that: (i) exposure of human plasma to gas phase CS causes both lipid peroxidation and protein oxidation, and endogenous ascorbic acid protects against lipid, but not protein, oxidation; (ii) whole CS causes protein oxidation, but does not induce lipid peroxidation; (iii) addition to plasma of aldehydes known to be present in CS causes protein damage, but does not induce either lipid peroxidation or oxidation of ascorbic acid; and (iv) exogenously added dihydrolipoic acid (DHLA) preserves ascorbic acid levels in plasma exposed to the gas phase of CS, and protects, to some extent, against lipid peroxidation; DHLA also protects against protein oxidation, whereas added glutathione (GSH) only protects against protein, but not lipid, oxidation.

Cigarette smoke oxidation of human plasma constituents

In vitro exposure of fresh human plasma to cigarette smoke (CS) was used as a model for reactions that could be occurring in CS-exposed respiratory tract lining fluids (RTLFs) and lung parenchyma. The central focus of this model was to characterize the consumption of endogenous plasma antioxidants in relationship to the appearance of oxidized proteins and lipids as a consequence of exposure to CS, or to aldehydes present in CS. The amelioration of CS-induced protein and lipid oxidation in plasma by the addition of selective exogenous antioxidants was also assessed. We found that: (i) exposure of human plasma to gas phase CS causes both lipid peroxidation and protein oxidation, and endogenous ascorbic acid protects against lipid, but not protein, oxidation; (ii) whole CS causes protein oxidation, but does not induce lipid peroxidation; (iii) addition to plasma of aldehydes known to be present in CS causes protein damage, but does not induce either lipid peroxidation or oxidation of ascorbic acid; and (iv) exogenously added dihydrolipoic acid (DHLA) preserves ascorbic acid levels in plasma exposed to the gas phase of CS, and protects, to some extent, against lipid peroxidation; DHLA also protects against protein oxidation, whereas added glutathione (GSH) only protects against protein, but not lipid, oxidation.

Antioxidant protection against hypochlorous acid in human plasma

Hypochlorous acid (HOCI) is a powerful oxidizing and chlorinating agent produced by the neutrophil enzyme myeloperoxidase. The antioxidant defenses of freshly prepared human plasma against HOCI/OCI- were explored. Addition of HOCI/OCI- to plasma caused rapid oxidation of ascorbic acid and thiol (-SH) groups but not of uric acid. Plasma -SH groups (which are known to be largely located on albumin) were quantitatively the most important scavenger of HOCI/OCI-, but adding extra ascorbate to plasma caused this molecule to have a more important scavenging role against HOCI/OCI-. Added HOCI/OCI- produced no detectable lipid peroxidation in plasma or depletion of lipid-soluble antioxidants (alpha-tocopherol or ubiquinol-10). No evidence of oxidative damage to protein amino acid residues (other than -SH) was detected by the carbonyl assay. It seems that -SH groups are a major target of attack by HOCI/OCI- in vivo, and plasma albumin may be an important protective antioxidant. Ascorbic acid might also play a protective role, especially in individuals supplemented with this vitamin. Ascorbate might also be important in extracellular fluids with low albumin concentrations such as synovial, respiratory tract lining, and cerebrospinal fluids.

No detrimental effects in delaying initiation of gonadotropin administration after pituitary desensitization with gonadotropin-releasing hormone agonist

OBJECTIVE

To determine if delaying initiation of exogenous gonadotropin administration after pituitary desensitization with gonadotropin-releasing hormone agonist (GnRH-a) is a realistic option to avoid scheduling clinical and laboratory work on weekends/holidays.

DESIGN, PATIENTS

A review of 57 in vitro fertilization (IVF) cycles in which, after pituitary desensitization with GnRH-a, initiation of gonadotropin administration were delayed in an attempt to avoid off-hour work. Thirty-eight IVF cohort cycles served as control.

SETTING

Tertiary medical center.

RESULTS

There were no statistically significant differences in ovarian response, dose of gonadotropin required, oocytes and embryos obtained, pregnancy rates, and abortion rates between groups. Eighty-three percent of the delayed cycles had clinical and laboratory work that fell within weekdays.

CONCLUSION

Delaying initiation of exogenous gonadotropin administration after pituitary desensitization had no detrimental effects on IVF outcomes. It may be used to avoid scheduling work on weekends/holidays.

Interaction of nitrogen dioxide with human plasma. Antioxidant depletion and oxidative damage

Nitrogen dioxide (NO2.) is often present in inhaled air and may be generated in vivo from nitric oxide. Exposure of human blood plasma to NO2. caused rapid losses of ascorbic acid, uric acid and protein thiol groups, as well as lipid peroxidation and depletions of alpha-tocopherol, bilirubin and ubiquinol-10. No increase in protein carbonyls was detected. Supplementation of plasma with ascorbate decreased the rates of lipid peroxidation, alpha-tocopherol depletion and loss of uric acid. Uric acid supplementation decreased rates of lipid peroxidation but not the loss of alpha-tocopherol. We conclude that ascorbic acid, protein -SH groups, uric acid and alpha-tocopherol may be important agents protecting against NO2. in vivo. If these antioxidants are depleted, peroxidation of lipids occurs and might contribute to the toxicity of NO2..

Modification of plasma proteins by cigarette smoke as measured by protein carbonyl formation

Exposure of human plasma to gas-phase (but not to whole) cigarette smoke (CS) produces oxidative damage to lipids [Frei, Forte, Ames & Cross (1991) Biochem. J. 277, 133-138], which is prevented by ascorbic acid. The ability of CS to induce protein damage was measured by the carbonyl assay and by loss of enzyme activity and protein -SH groups. Both whole and gas-phase CS caused formation of carbonyls in human plasma, which was partially inhibited by GSH but not by ascorbic acid or metal-ion-chelating agents. Isolated albumin exposed to CS showed much faster carbonyl formation (per unit protein) than did whole plasma; damage to isolated albumin was partially prevented by chelating agents. Isolated creatine kinase (CK) lost activity upon exposure to CS much faster than did CK in plasma. Direct addition to plasma of mixtures of some or all of the aldehydes reported to be present in CS caused protein carbonyl formation and inactivation of CK, but neither occurred to the extent produced by CS exposure.

Potentiation of oxidative damage to proteins by ultraviolet-A and protection by antioxidants

We have studied the damage of alcohol dehydrogenase (ADH) and glyceraldehyde 3-phosphate dehydrogenase (GAPD) induced by Fe++/EDTA + H2O2 in combination with UV-A (main output at 365 nm). Enzyme inactivation, formation of hydroxyl radicals (measured in the absence of enzymes), increase in protein carbonyls, oxidation of sulfhydryl (SH) groups, loss of native protein fluorescence, and enhanced protease degradation were used to determine protein damage. Hydroxyl radical production was greatly enhanced by the combination of UV-A with Fe++/EDTA + H2O2. The combined treatment increased protein carbonyls but decreased native protein fluorescence and SH groups. The combined treatment caused turbidity in GAPD but not in ADH, whereas trypsin susceptibility was increased more in ADH than in GAPD. These measurements of protein oxidation correlated well with enzyme activities. Glyceraldehyde 3-phosphate dehydrogenase and dithiothreitol were most protective against such damage, while hydroxyl radical and singlet oxygen scavengers were partially effective. Superoxide dismutase had no effect. Thus, UV-A potentiation of protein damage induced by FE++/EDTA + H2O2 appeared to involve hydroxyl radicals and perhaps singlet oxygen but not superoxide radicals. The damage to proteins induced by combination of UV-A with physiological oxidants, iron ions and H2O2 may be relevant to UV-A-induced skin and tissue damage.

Glutathione and antioxidants protect microsomes against lipid peroxidation and enzyme inactivation

The study investigated the relationship between lipid peroxidation and enzyme inactivation in rat hepatic microsomes and whether prior inactivation of aldehyde dehydrogenase (ALDH) exacerbated inactivation of other enzymes. In microsomes incubated with 2.5 microM iron as ferric sulfate and 50 microM ascorbate, ALDH, glucose-6-phosphatase (G6Pase) and cytochrome P450 (Cyt-P450) levels decreased rapidly and concurrently with increased levels of thiobarbituric acid-reactive substances. Microsomal glutathione S-transferase and nicotinamide adenine dinucleotide phosphate-cytochrome c reductase were little affected during 1 hr of incubation. Addition of reduced glutathione partially protected and N,N'-diphenyl-p-phenylenediamine and butylated hydroxytoluene completely protected microsomes against inactivation of ALDH, G6Pase and Cyt-P450, as well as lipid peroxidation induced by iron and ascorbate. ALDH was more susceptible than G6Pase to inactivation by iron and ascorbate, and was thus an excellent marker for oxidative stress. Inhibition of ALDH by cyanamide injection of rats exacerbated the inactivation of G6Pase in microsomes incubated with 0.1 mM, but not 25 microM 4-hydroxynonenal (4-HN). 4-HN did not stimulate lipid peroxidation. Thus, 4-HN may play a minor role in microsomal enzyme inactivation. In contrast, lipid peroxyl radicals play an important role in microsomal enzyme inactivation, as evidenced by the prevention of both lipid peroxidation and enzyme inactivation by chain-breaking antioxidants.

Vitamin E, diethylmaleate and bromotrichloromethane interactions in oxidative damage in vivo

In vivo interactions of vitamin E with diethylmaleate (DEM) and bromotrichloromethane (CBrCl3) were examined in rats fed a diet either without vitamin E or supplemented with 30 IU dl-alpha-tocopheryl acetate/kg. Groups of rats within each dietary group were given two injections 30 min apart. One group received two injections of the mineral oil carrier. The other groups were injected with either DEM and mineral oil, mineral oil and CBrCl3, or DEM and CBrCl3. The rats were killed 10 min after the second injection. Measurements were made of hepatic GSH, thiobarbituric acid-reactive substances (TBARS) as a lipid peroxidation index, and 11 enzymes as potential markers of oxidant damage. Special focus was placed on reactive cysteine-containing aldehyde dehydrogenase (ALDH). Although dietary vitamin E protected ALDH, the enzyme was highly susceptible to oxidant damage. ALDH activity was correlated with GSH (r = 0.83, p less than 0.001) and there was an inverse relationship between the logarithmic values of ALDH activity and TBARS (r = 0.78, p less than 0.001). Similar results were observed for a number of other enzymes when GSH depletion preceded oxidant treatment. Two-way analysis of variance revealed significant effects of vitamin E and of injection treatments on hepatic GSH. There was a significant interaction between vitamin E and the injection treatments on the activities of five enzymes. The results suggested that vitamin E and GSH functioned together to protect sensitive enzymes against oxidant stress. The sensitive enzymes may be useful markers of hepatic damage in vivo.

Effect of dietary menhaden oil and vitamin E on in vivo lipid peroxidation induced by iron

Weanling rats were fed diets containing 10% menhaden oil (MO) or 10% corn oil-lard (1:1, COL) with low (less than or equal to 5 IU/kg) or supplementary (35 IU/kg) vitamin E for six weeks. The rats were killed 30 min after injection with 24 mg iron/kg as ferrous chloride because thiobarbituric acid-reactive substances (TBARS) in liver homogenates were highest at 30 min after injection of iron into rats fed a standard diet. Tissue homogenates were used either without incubation (zero-time) or after incubation at 37 degrees C for 1 hr. In addition to TBARS and conjugated dienes, headspace hexanal and total volatiles (TOV) determined by capillary gas chromatography were useful indices of lipid peroxidation since they were decreased by vitamin E supplementation and were increased with increasing iron dose. Regardless of the dietary lipid used, vitamin E supplementation decreased headspace hexanal, TOV, TBARS and conjugated dienes in both zero-time and incubated homogenates of liver and kidney. Dietary MO increased TBARS in both zero-time and incubated homogenates of tissue from rats injected with iron. In contrast, dietary MO decreased hexanal and TOV in incubated tissue homogenates. The study demonstrated the usefulness and limitations of using hexanal and TOV as indices of lipid peroxidation.

Lipid peroxidation in rat tissue slices: effect of dietary vitamin E, corn oil-lard and menhaden oil

Rats were fed for 5 weeks either 10% (w/w) menhaden oil (MO) or a 10% corn oil-lard (COL) mixture (1:1) in diets with less than or equal to 5 IU or less than or equal to 2 IU/kg vitamin E, respectively, or the same diets supplemented with d-alpha-tocopheryl succinate to a total of 35 and 180 IU vitamin E/kg, respectively. Slices of liver and heart from these rats were used to study lipid peroxidation in vitro. Thiobarbituric acid-reactive substances (TBARS) were measured in the medium after incubation of the slices at 37 degrees C for 1 hr in the absence (uninduced) and presence of 0.5 mM tert-butyl hydroperoxide (induced). The release of TBARS from slices of heart and liver from rats fed either lipid decreased with increasing levels of dietary vitamin E. At the same level of dietary vitamin E, TBARS release was greater for slices of liver and heart from the MO-fed rats than from the COL-fed rats. Application of the TBARS data to a model simulating the experimental conditions showed a good correlation (r = 0.95, p less than 0.001) between experimental and simulated values. Of the 16:0-22:6 fatty acids measured in liver from MO-fed rats, 15.4% was n-6 fatty acids and 29.9% was n-3 fatty acids; in liver from COL-fed rats, the respective values were 37.4% and 3.7%. Liver and kidney vitamin E levels were unaffected by the dietary lipid.(ABSTRACT TRUNCATED AT 250 WORDS)