DNA damage as a potential marker in the clinical follow-up of female patients with treated cancer / Daño del ADN como marcador potencial en el seguimiento clínico de pacientes femeninas con cáncer tratado

Abstract Objective: To identify individual differences in the basal damage (DB) of peripheral leukocyte DNA from women with cancer in remission. Methods: Cross-sectional analytical study in which 24 women with cancer in remission from different locations and 24 supposedly healthy women participated. The alkaline comet assay and the neutral variant were used to determine single-stranded breaks (DB-A), and double-stranded DNA breaks (DB-N), respectively. Results: Although there were no differences between the mean values of DNA damage in patients and controls (DB-N: p = 0.43 and DB-A: p = 0.13), 41.6% of the patients presented an increase of one type or another of DNA breaks, with respect to the corresponding cut-off points of the control women. DB-N was correlated with increasing age (r2 = 0.1833; r = 0.4281; p = 0.036) in the patients. DB-A was elevated in those who had received anticancer combination therapy (p = 0.024) and in those who were undergoing treatment with tamoxifen (p = 0.033); while it was decreased in those that consumed antioxidants (p = 0.006) and in those that combined tamoxifen and antioxidants (p = 0.020). Conclusions: Individual differences were identified in both types of DNA strand breaks that are of medical interest in the studied patients. Baseline DNA damage determined by comet assay is a potential tool in the clinical follow-up of cancer patients in remission.

Resumen Objetivo: Identificar diferencias individuales en el daño basal (DB) del ADN de leucocitos periféricos de mujeres con cáncer en remisión. Métodos: Estudio analítico de corte transversal en el que participaron 24 mujeres con cáncer en remisión de diferentes localizaciones y 24 mujeres supuestamente sanas. Se utilizó el ensayo cometa alcalino y la variante neutral para determinar roturas de simple hebra (DB-A), y roturas de doble hebra del ADN (DB-N), respectivamente. Resultados: Aunque no hubo diferencias entre los valores medios del daño del ADN de pacientes y controles (DB-N: p=0,43 y DB-A: p=0,13), el 41,6% de las pacientes presentó aumento de un tipo u otro de roturas del ADN, respecto a los correspondientes puntos de corte de las mujeres controles. El DB-N estuvo correlacionado con el incremento de la edad (r2 = 0,1833; r = 0,4281; p = 0,036) en las pacientes. El DB-A estuvo elevado en aquellas que habían recibido politerapia anticáncer (p = 0,024) y en las que estaban realizando tratamiento con tamoxifeno (p=0,033); mientras estuvo disminuido en las que consumieron antioxidantes (p=0,006) y en las que combinaron tamoxifeno y antioxidantes (p=0,020). Conclusiones: Se identificaron diferencias individuales en ambos tipos de roturas de hebra del ADN que resultan de interés médico en las pacientes estudiadas. El daño basal del ADN determinado por ensayo cometa es una herramienta potencial en el seguimiento clínico de pacientes con cáncer en remisión.

Mycobacterium tuberculosis promotes genomic instability in macrophages

BACKGROUND Mycobacterium tuberculosis is an intracellular pathogen, which may either block cellular defensive mechanisms and survive inside the host cell or induce cell death. Several studies are still exploring the mechanisms involved in these processes. OBJECTIVES To evaluate the genomic instability of M. tuberculosis-infected macrophages and compare it with that of uninfected macrophages. METHODS We analysed the possible variations in the genomic instability of Mycobacterium-infected macrophages using the DNA breakage detection fluorescence in situ hybridisation (DBD-FISH) technique with a whole human genome DNA probe. FINDINGS Quantitative image analyses showed a significant increase in DNA damage in infected macrophages as compared with uninfected cells. DNA breaks were localised in nuclear membrane blebs, as confirmed with DNA fragmentation assay. Furthermore, a significant increase in micronuclei and nuclear abnormalities were observed in infected macrophages versus uninfected cells. MAIN CONCLUSIONS Genomic instability occurs during mycobacterial infection and these data may be seminal for future research on host cell DNA damage in M. tuberculosis infection.

Pyruvate Protects Giardia Trophozoites from Cysteine-Ascorbate Deprived Medium Induced Cytotoxicity

Giardia lamblia, an anaerobic, amitochondriate protozoan parasite causes parasitic infection giardiasis in children and young adults. It produces pyruvate, a major metabolic product for its fermentative metabolism. The current study was undertaken to explore the effects of pyruvate as a physiological antioxidant during oxidative stress in Giardia by cysteine-ascorbate deprivation and further investigation upon the hypothesis that oxidative stress due to metabolism was the reason behind the cytotoxicity. We have estimated intracellular reactive oxygen species generation due to cysteine-ascorbate deprivation in Giardia. In the present study, we have examined the effects of extracellular addition of pyruvate, during oxidative stress generated from cysteine-ascorbate deprivation in culture media on DNA damage in Giardia. The intracellular pyruvate concentrations at several time points were measured in the trophozoites during stress. Trophozoites viability under cysteine-ascorbate deprived (CAD) medium in presence and absence of extracellular pyruvate has also been measured. The exogenous addition of a physiologically relevant concentration of pyruvate to trophozoites suspension was shown to attenuate the rate of ROS generation. We have demonstrated that Giardia protects itself from destructive consequences of ROS by maintaining the intracellular pyruvate concentration. Pyruvate recovers Giardia trophozoites from oxidative stress by decreasing the number of DNA breaks that might favor DNA repair.

Baicalein Protects Human Skin Cells against Ultraviolet B-Induced Oxidative Stress

Baicalein (5,6,7-trihydroxy-2-phenyl-chromen-4-one) is a flavone, a type of flavonoid, originally isolated from the roots of Scutellaria baicalensis. This study evaluated the protective effects of baicalein against oxidative damage-mediated apoptosis induced by ultraviolet B (UVB) radiation in a human keratinocyte cell line (HaCaT). Baicalein absorbed light within the wavelength range of UVB. In addition, baicalein decreased the level of intracellular reactive oxygen species (ROS) in response to UVB radiation. Baicalein protected cells against UVB radiation-induced DNA breaks, 8-isoprostane generation and protein modification in HaCaT cells. Furthermore, baicalein suppressed the apoptotic cell death by UVB radiation. These findings suggest that baicalein protected HaCaT cells against UVB radiation-induced cell damage and apoptosis by absorbing UVB radiation and scavenging ROS.

Minimal endoscopic changes in non-erosive reflux disease / Alterações endoscópicas mínimas na doença do refluxo não erosiva

BACKGROUND: Gastroesophageal reflux disease is an increasingly common condition worldwide causing a considerable economic impact. More than half the patients with clinical symptoms of reflux disease display no mucosal erosions on esophagogastroduodenoscopy, making it impossible to confirm the diagnosis without further investigations. AIM: To evaluate the correlation between minimal endoscopic changes on white-light esophagogastroduodenoscopy (carditis, mucosal thickening and invisibility of vessels) and histologic changes observed in distal esophageal biopsies in a sample of patients with symptoms suggestive of reflux disease, and to verify the specificity of these symptoms for non-erosive reflux disease. METHODS: Retrospective, cross-sectional study based on information retrieved from a digital database at a Brazilian hospital for the period March-October, 2012. The sample consisted of previously untreated, non-smoking subjects aged >18 years with symptoms suggestive of reflux disease but no esophageal erosions, submitted to esophagogastroduodenoscopy and distal esophageal biopsy. RESULTS: The final sample included 23 subjects. The most frequently observed change was invisibility of vessels (n=21; 91.3%), followed by mucosal thickening (n=15; 65.2%) and carditis (n=5; 21.7%). The correlation coefficient between each variable and the anatomopathological diagnosis was 0.386 for body mass index, 0.479 for mucosal thickening, -0.116 for invisibility of vessels, 0.306 for carditis and 0.462 for hiatal hernia. CONCLUSION: All patients displayed minimal endoscopic changes on esophagogastroduodenoscopy, but only mucosal thickening revealed a moderately significant correlation with severity of esophagitis, although increased body mass index values and the presence of hiatal hernia were also associated. .

RACIONAL: Doença do refluxo gastroesofágico é condição cada vez mais comum em todo o mundo causando impacto econômico considerável. Mais da metade dos pacientes com sintomas clínicos da doença não apresentam erosões endoscópicas da mucosa, o que torna impossível confirmar o diagnóstico sem outras investigações. OBJETIVO: Avaliar a correlação entre mudanças mínimas endoscópicas em endoscopia digestiva alta de luz branca (cardite, espessamento da mucosa e invisibilidade de vasos) e as alterações histológicas observadas em biópsias distais de uma amostra de pacientes com sintomas sugestivos de doença do refluxo, e para verificar a especificidade desses sintomas para a doença não-erosiva. MÉTODOS: Estudo retrospectivo, transversal, com base em informações obtidas a partir de uma base de dados digital em um hospital brasileiro no período de março/outubro de 2012. A amostra foi composta por indivíduos não tratados previamente, não fumantes, >18 anos, com sintomas sugestivos de doença do refluxo, mas sem erosões esofágicas submetidos à endoscopia digestiva alta e biópsia de esôfago distal. RESULTADOS: A amostra final incluiu 23 indivíduos. A alteração mais frequente foi invisibilidade dos vasos (n=21; 91,3%), seguido por espessamento de mucosa (n=15; 65,2%) e cardite (n=5; 21,7%). O coeficiente de correlação entre cada variável e o diagnóstico anatomopatológico foi 0,386 para o índice de massa corporal, 0,479 para espessamento de mucosa, -0,116 para a invisibilidade de vasos, 0,306 para carditis e 0,462 para hérnia hiatal. CONCLUSÃO: Todos os pacientes apresentaram alterações endoscópicas mínimas, mas apenas espessamento da mucosa revelou correlação moderadamente significativa com a gravidade da esofagite, apesar do aumento dos valores no índice de massa corporal e da presença de hérnia hiatal também estarem associados. .

Temporal Pattern of DNA Breaks in Human Ovarian Cancer Cells after Exposure to Nanosecond Electric Pulses / 生物医学工程学杂志

This study aims to explore the temporal pattern of DNA breaks induced by nanosecond electric pulses (nsEP) in cisplatin-sensitive and cisplatin-resistant human ovarian cancer cells. Human ovarian cancer cells A2780 (cisplatin-sensitive subline) and C30 (cisplatin-resistant subline) were exposed to nsEP. Sham exposed groups were shame exposed to nsEP. Cell viability was determined using CCK-8 assay after 0 h, 4 h, 8 h, 12 h and 24 h, respectively, and the percentage of dead cells was calculated. The DNA break was detected with the alkaline single cell gel electrophoresis (comet assay), and the 75th percentiles of TL (tail length), TM (tail moment) and OTM (Olive tail moment) were measured. Cell viability displayed an early decrease and late increase, with the valley value seen at 8 h. Percentages of cell death and comet-formed in A2780 cells were higher than those in C30 cells (P < 0.05) at 8 h, respectively. TL, TM and OTM in C30 cells were less than those in A2780 cells (P < 0.05). The percentage of comet-formed correlated with that of cell death in either A2780 (r = 0.997, P < 0.05) or C30 (r = 0.998, P < 0.05) cells. DNA breaks induced by nsEP in cisplatin-sensitive cells differred from that in resistant cells, and DNA break resulted in fraction of cell death.

Effect of electromagnetic field exposure on the reproductive system / 대한생식의학회지

The safety of human exposure to an ever-increasing number and diversity of electromagnetic field (EMF) sources both at work and at home has become a public health issue. To date, many in vivo and in vitro studies have revealed that EMF exposure can alter cellular homeostasis, endocrine function, reproductive function, and fetal development in animal systems. Reproductive parameters reported to be altered by EMF exposure include male germ cell death, the estrous cycle, reproductive endocrine hormones, reproductive organ weights, sperm motility, early embryonic development, and pregnancy success. At the cellular level, an increase in free radicals and [Ca2+]i may mediate the effect of EMFs and lead to cell growth inhibition, protein misfolding, and DNA breaks. The effect of EMF exposure on reproductive function differs according to frequency and wave, strength (energy), and duration of exposure. In the present review, the effects of EMFs on reproductive function are summarized according to the types of EMF, wave type, strength, and duration of exposure at cellular and organism levels.

Effect of electromagnetic field exposure on the reproductive system / 대한생식의학회지

The safety of human exposure to an ever-increasing number and diversity of electromagnetic field (EMF) sources both at work and at home has become a public health issue. To date, many in vivo and in vitro studies have revealed that EMF exposure can alter cellular homeostasis, endocrine function, reproductive function, and fetal development in animal systems. Reproductive parameters reported to be altered by EMF exposure include male germ cell death, the estrous cycle, reproductive endocrine hormones, reproductive organ weights, sperm motility, early embryonic development, and pregnancy success. At the cellular level, an increase in free radicals and [Ca2+]i may mediate the effect of EMFs and lead to cell growth inhibition, protein misfolding, and DNA breaks. The effect of EMF exposure on reproductive function differs according to frequency and wave, strength (energy), and duration of exposure. In the present review, the effects of EMFs on reproductive function are summarized according to the types of EMF, wave type, strength, and duration of exposure at cellular and organism levels.

Variant fusion transcripts and genomic DNA breakpoint of sil-tal1 in T-ALL cells / 中国实验血液学杂志

The aim of this study was to investigate the nucleotide sequence of one distinct fusion transcript of sil-tal1 in childhood T-ALL. The PCR product was cloned into plasmid vector and then sequenced. Genomic DNA was analyzed with PCR using the designed primer pairs representing distinct sequences. The product was sequenced and analyzed with database. The results indicated that 4 different fusion transcripts were detected at cDNA level, in which a part of exons or introns of sil are reserved respectively, and some additions and deletions existed. After analyzing genomic DNA sequence of leukemic cells, the breakpoint in gene sil of this case was proved to be different at DNA level from references. Hence, the sil-tal1 rearrangement was defined to be a new type. It is concluded tal1 rearrangement of leukemic cells in this case is a new type, which expresses classical and at least 3 variant fusion transcripts, presumably caused by extraordinary mechanisms of splicing and transcription in leukemic stem cells.

DNA degradation by aqueous extract of Aloe vera in the presence of copper ions.

The plant Aloe vera has long been used in medicine, as dietary supplements and for cosmetic purposes. Aloe vera extracts are a rich source of polyphenols, such as aloin and aloe emodin and have shown a wide range of pharmacological properties, including anti-inflammatory and anti-cancer properties. The bioactive component aloe emodin has been reported to induce apoptosis in various cancer cell lines. Many of the biological activities of Aloe vera have been attributed to its antioxidant properties. However, most plant-derived polyphenols that are also present in Aloe vera may exhibit pro-oxidant properties either alone or in the presence of transition metals, such as copper. Previous reports from this laboratory have implicated the pro-oxidant action as one of the mechanisms for their anti-cancer properties. In the present paper, we show that aqueous extract of Aloe vera is also able to cause DNA degradation in the presence of copper ions. Further, the extract is also able to reduce Cu(II) to Cu(I) and generate reactive oxygen species, such as superoxide anion and hydroxyl radicals in a dose-dependent manner, which correlates with ability of the extract to cause DNA breakage. Thus, the study shows that in addition to antioxidant activity, Aloe vera extract also possess pro-oxidant properties, leading to oxidative DNA breakage.

Estimates of DNA strand breakage in bottlenose dolphin (Tursiops truncatus) leukocytes measured with the Comet and DNA diffusion assays

The analysis of DNA damage by mean of Comet or single cell gel electrophoresis (SCGE) assay has been commonly used to assess genotoxic impact in aquatic animals being able to detect exposure to low concentrations of contaminants in a wide range of species. The aims of this work were 1) to evaluate the usefulness of the Comet to detect DNA strand breakage in dolphin leukocytes, 2) to use the DNA diffusion assay to determine the amount of DNA strand breakage associated with apoptosis or necrosis, and 3) to determine the proportion of DNA strand breakage that was unrelated to apoptosis and necrosis. Significant intra-individual variation was observed in all of the estimates of DNA damage. DNA strand breakage was overestimated because a considerable amount (~29 percent) of the DNA damage was derived from apoptosis and necrosis. The remaining DNA damage in dolphin leukocytes was caused by factors unrelated to apoptosis and necrosis. These results indicate that the DNA diffusion assay is a complementary tool that can be used together with the Comet assay to assess DNA damage in bottlenose dolphins

Back to the Ends: Chromosomal DNA

Nucleic scids transfer the genetic information for serving a central biological purpose. The nucleic acids are polymers of nucleotides and they are mainly ribonucleic acid(RNA) and deoxyribonucleic acid(DNA). The nucleotides are stoichiometrically composed of five-carbon sugars, nitrogeneous bases, and phosphoric acids. The chemistry of nucleic acids and characteristics of different genomes are decribed for further study. Most of DNA genomes tend to be circular including bacterial genomes and eukaryotic mitochondrial DNA. Eukaryotic chromosomes in cells, in contrast, are generally linear. The ends of linear chromosomes are called telomeres. The genomes of different species, such as mammals, plants, invertebrates can be compared with the chromosome ends. The telomeric complex allows cells to distinguish the random DNA breaks and natural chromosomal ends. The very ends of chromosomes cannot be replicated by any ordinary mechanisms. The shortening of telomeric DNA templates in semiconservative replication is occurred with each cell division. The short telomere length is critically related to aging, tumors and dieases.

Biomarkers of induced electromagnetic field and cancer.

The present article delineates the epidemiological and experimental studies of electromagnetic field which affects various tissues of human body. These affects lead to cell proliferation, which may lead to cancer formation. Certain biomarkers have been identified which are one way or the other responsible for tumor promotion or co-promotion. These are (i) melatonin, a hormone secreted by pineal gland, (ii) Ca2+, which is essential in the regulation of the resting membrane potential and in the sequence of events in synaptic excitation and neurotransmitter, release are affected by electromagnetic field, (iii) ornithine decarboxylase (ODC), a rate-limiting enzyme in the biosynthesis of polyamines, considered as a useful biological marker; over expression of ODC can cause cell transformation and enhancement of tumor promotion. (iv) protein kinase is an enzyme, which transfers phosphate groups from ATP to hydroxyl groups in the amino acid chains of acceptor proteins, and (v) Na+-K+ ATPase, which transports sodium and potassium ions across the membrane has a critical role in living cells. The various possible mechanisms depending upon non equilibrium thermodynamics, co-operativism, stochastic and resonance are discussed as possible models of signal transduction in cytosol, thereby controlling the transcription phenomena. Finally a mechanism comprising the extremely low frequency and radio frequency (RF)/microwave (MW) modulated field is compared.

Mechanism of the dysfunction of the bull spermatozoa treated with cadmium / 中华男科学杂志

<p><b>OBJECTIVE</b>Heavy metals such as cadmium (Cd) are widely distributed in the environment as industrial pollutants and characterized by their ability to affect the male reproductive system. The objective of the present study was to test the effect of Cd in the concentration range from 10 to 1000 micromol/L, in vitro, on the membrane and DNA integrity, motility, and ability of sperm to undergo acrosomal exocytosis in Holstein bull spermatozoa.</p><p><b>METHODS</b>Bull semen samples were processed for sperm analyses using semen-diluting fluid, PBS. Membrane integrity of the processed bull sperm was evaluated by lipoperoxidation (LPO) test. Gelatin digestion test was performed to determine the ability of bull spermatozoa to undergo acrosomal exocytosis. Single cell gel electrophoresis (SCGE) assay was performed to detect the DNA strand breaks and alkali labile damages in the individual cell.</p><p><b>RESULTS</b>We found a significant increase in the lipoperoxidation (LPO) indicating the deleterious effect of Cd on the sperm membrane integrity. This effect was prominent at the concentration of 1000 micromol/L Cd. There was a negative correlation between LPO rate and the percentage of motile spermatozoa (r = -0.94, P < 0.001). The gelatin digestion test indicated that Cd caused a decline in the percentage of acrosomal exocytosis of bull spermatozoa. A reverse correlation was also found between LPO rate and the percentage of halos (r = -0.97, P < 0.001). Data obtained from the comet assay revealed that Cd was capable of inducing DNA breaks in the sperm nuclei. Almost 93% of DNA damages were double-stranded breaks. The correlation between LPO rate and the percentage of DNA breaks was found to be 0.95 (P < 0.001).</p><p><b>CONCLUSION</b>Collectively, Cd induced membrane impairments, lowered motility, DNA breaks and a decreased rate in the acrosome reaction of bull spermatozoa, leading to sperm dysfunction. Entering Cd in the male gonads and seminal plasma may exert deleterious effects on the animal sperm cells.</p>

Expression of recombination-activating genes and T cell receptor gene recombination in the human T cell leukemia cell line / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Recent studies have suggested that mature T cells can change their specificity through reexpression of recombination-activating genes (RAG) and RAG-mediated V(D)J recombination. This process is named receptor revision and has been observed in mature peripheral T cells from transgenic mice and human donors. However, whether thebreceptor revision in mature T cells is a random or orientated process remains poorly understood. Here we used the Jurkathuman T cell line, which represents a mature stage of T cell development, as a model to investigate the regulation of Tcell receptor (TCR) gene recombination.</p><p><b>METHODS</b>TCR Dbeta-Jbeta signal joint T cell receptor excision DNA circles (sjTRECs) were determined by nested and seminested PCR. Double-strand DNA breaks at recombination signal sequences (RSSs) in the TCRVbeta chain locus were detected by ligation-mediated-PCR. Further analysis of the complementarity-determining region 3 (CDR3) size of the TCRVbeta chain was examined by the TCR GeneScan technique.</p><p><b>RESULTS</b>RAG1, RAG2, and three crucial components of the nonhomologous DNA end-joining (NHEJ) pathway were readily detected in Jurkat. Characteristics of junctional diversity of Dbeta2-Jbeta2 signal joints and ds RSS breaks associated with the Dbeta2 5' and Dbeta 2 3' sites were detected in DNA from Jurkat cells. CDR3 size and the gene sequences of the TCRVbeta chain did not change during cell proliferation.</p><p><b>CONCLUSIONS</b>RAG1 and RAG2 and ongoing TCR gene recombination are coexpressed in Jurkat cells, but the ongoing recombination process may not play a role in modification of the TCR repertoire.However, the results suggest that Jurkat could be used as a model for studying the regulation of RAGs and V(D)J recombination and as a "special" model of the coexistence of TCR gene rearrangements and "negative" receptor revision.</p>

In vitro cytotoxic and non-genotoxic effects of gutta-percha solvents on mouse lymphoma cells by single cell gel (comet) assay

Chloroform and eucalyptol are widely used in clinical dentistry as gutta-percha solvents. However, these compounds may represent a hazard to human health, especially by causing injury to genetic apparatus and/or inducing cellular death. In this study, the genotoxic and cytotoxic potentials associated with exposure to chloroform and eucalyptol were assessed on mouse lymphoma cells in vitro by the single cell gel (comet) assay and trypan blue exclusion test, respectively. Both gutta-percha solvents proved to be cytotoxic at the same levels in concentrations of 2.5, 5 and 10 muL/mL (p<0.05). On the other hand, neither of the solvents induced DNA breakage. Taken together, these results suggest that although both tested compounds (chloroform and eucalyptol) are strong cytotoxicants, it seems that they are not likely to increase the level of DNA damage on mammalian cells.

Clorofórmio e eucaliptol são amplamente utilizados na clínica odontológica como solventes de guta-percha. Entretanto, estes compostos podem representar um perigo à saúde humana, especialmente por causar danos ao aparelho genético e/ou induzir morte celular. Neste estudo, o potencial genotóxico e citotóxico associado à exposição ao clorofórmio e eucaliptol foram avaliados em células de linfoma murino in vitro pelo teste de células individualizadas (teste do cometa) e pelo teste do azul de tripan, respectivamente. Ambos os solventes de guta-percha provaram ser citotóxicos nos mesmos níveis em concentrações de 2,5, 5 e 10 miL/mL (p<0.05). Por outro lado, nenhum dos dois solventes induziu danos ao DNA. Em conclusão, esses resultados sugerem que ambos os compostos testados (clorofórmio e eucaliptol) são potentes citotoxinas, mas não representam um fator que aumenta o nível de danos no DNA em células de mamíferos.

Inhibitory effect of agarohexaose on antimycin A induced generation of reactive oxygen species / 药学学报

<p><b>AIM</b>To evaluate the hepatocyte protective effect of agarohexaose against indirect oxidative stress injury induced by antimycin A.</p><p><b>METHODS</b>Antimycin A was used to induce oxidative injury of human hepatocyte L-02. The oxidative degree in cells was detected by dichlorofluorescin diacetate (DCFH-DA) and the fluorescence generation was recorded by flow cytometer and fluorescent microscope. The apoptosis of L-02 cells induced by oxidation was identified by TUNEL test, and the morphologic features of cells were also observed.</p><p><b>RESULTS</b>Agarohexaose at concentration of 1 mg x mL(-1) inhibited the oxidation of DCFH into DCF significantly. The fluorescence intensity and oxidized cell number decreased after the incubation with agarohexaose. The photomicrographs of antimycin A and agarohexaose treated cells revealed that agarohexaose could reduce the apoptotic morphologic features. The TUNEL results also indicated that the number of apoptotic cells decreased significantly after the treatment of agarohexaose.</p><p><b>CONCLUSION</b>Agarohexaose could inhibit the sudden increase reactive oxygen species (ROS) in cells significantly, and it also protected cells against oxidative stress injury in vitro.</p>

Hyperthermia-induced Apoptosis is Independent upon DNA Strand Breaks in Human Lymphoid Cells

Heat shock (43oC for 60 minutes) is sufficient to induce apoptosis in a wide number of cell lines. In this study, we asked whether DNA strand breaks are responsible for this phenomenon. Using the highly sensitive comet assay for DNA damage detection, we were unable to demonstrate DNA breaks immediately after heat shock in Raji human lymphoid cells. It showed that DNA breaks were not necessary for hyperthermic apoptosis, since its activity is indicative of DNA lesions. Here, we present a suggestion that a protein (s) is the major target for heat shock apoptosis. We firstly found glycerol, which reportedly stabilizes protein structure, showed a protective effect in Raji cells against hyperthermic apoptosis. In addition, quercetin, which modulates transcription of the heat shock protein family members, enhanced apoptotic death induced by hyperthermia. Furthermore, Raji cells are protected by a pre-mild heat treatment prior to the killing dose of heat shock.

Study of DNA damage with neuronal ischemia/reperfusion in vitro / 中国应用生理学杂志

<p><b>AIM AND METHODS</b>To investigate DNA strand damage in a model of cerebral ischemia/reperfusion injury in vitro, model of ischemia/reperfusion was produced by incubating the primary neuronal cultures to various durations of hypoxia and glucose deprivation (HGD). DNA single and double strand breaks were detected using PANT and TUNEL staining respectively.</p><p><b>RESULTS</b>A few cell death occurred after 2 h of HGD. Less than 30 percent of cell died after 4 h of HGD, whereas 6-8 h of HGD resulted in cell death in 80 percent of neurons. Neuronal cell death reached the peak 10-18 h after 6 h of HGD, while it took as early as 2 h after 8 h of HGD. Following HGD, PANT positive cells were remarkably increased, which was proportional to the duration of HGD. At 5 minutes after 2, 4, 6 or 8 h of HGD, PANT positive cells were 30%, 50%, 80%, 90% respectively. Meanwhile, no determined in another cultures, DNA double strain breaks were not significantly increased.</p><p><b>CONCLUSION</b>DNA strain breaks is a very early event of DNA damage following in vitro ischemia/reperfusion, especially DNA single strain breaks.</p>

Study on hereditary toxicity of bass wood dust / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To explore the genotoxicity of bass wood dust.</p><p><b>METHODS</b>Micronucleus frequency in peripheral lymphocytes of workers exposed to bass wood dust in a match factory were examined, solution of bass wood dust emmersion was prepared and the effect on micronucleus frequency in poly-dyeing red blood cell of mice's sternum marrow was also detected. Single cell gel electrophoresis assay was used to detect DNA damage in liver cell, the level of oxygen free radical, lipid peroxidation(MDA) in the liver and the activity of superoxide dismutase(SOD) in red blood cells were also studied.</p><p><b>RESULTS</b>The positive frequency of micronucleus in bass wood-exposed workers with different length of service (0-, 5-, > or = 10 a) were 50.0%, 51.9%, 50.0% respectively, significantly higher (P < 0.01) than that of the control group(4.5%). A dose-effect relationship could also be found in the mice's micronucleus frequency study(r = 0.78, P < 0.01). The activities of SOD[(10.98 +/- 5.74), (15.70 +/- 7.54), (29.63 +/- 14.97) microgram/g Hb] were significantly lower than that of control group[(35.80 +/- 12.92) microgram/g Hb], and the level of MDA[(4.93 +/- 0.90), (4.61 +/- 1.06), (4.33 +/- 0.69) mmol/g liver] were significantly higher than that of the control group[(2.51 +/- 0.34) mmol/g liver]. Single cell gel electrophoresis study showed DNA strand breaks increased with the dose increase and the level of oxygen free radical also increased with the dose increase.</p><p><b>CONCLUSION</b>Bass wood dust may have certain degree of genotoxicity.</p>