Genetic susceptibility of newborn daughters to oxidative stress

A central question in risk assessment is whether newborns' susceptibility to mutagens is different from that of adults. Therefore we investigated whether genotype and/or the DNA strand break repair phenotype in combination with the MN assay would allow estimation of the relative sensitivity of a newborn as compared to his mother for oxidative DNA damage. We compared the in vitro genetic susceptibility for H2O2 in PBMC of 17 mother-newborn daughter pairs taking into account genotypes for relevant DNA repair (hOGG1, XRCC1, XRCC3, XPD) and folate metabolism (MTHFR) polymorphisms. After in vitro challenge with H2O2 the repair capacity was assessed by the Comet assay and chromosome/genome mutations by the cytokinesis-block MN assay. No statistically significant differences were found between mothers and their newborn daughters either for initial DNA damage or for residual DNA damage. Mothers showed higher background frequencies of MN as compared to their newborn daughters, due to the age factor. This was confirmed by significantly higher frequencies of MN observed in mothers versus newborn daughters for several genotypes. No genotype with a significant effect on DNA repair capacity in newborns was identified. Concerning MN frequencies, however, newborns carrying the variant XRCC3(241) genotype might be at higher risk for the induction of MN by oxidative stress. Multivariate analysis revealed a significant protective effect of maternal antioxidant supplementation during pregnancy against oxidative DNA damage in newborns in terms of MN frequencies. However, these conclusions might not be extrapolable to other types of DNA damage and need confirmation in a study on a larger population.     

Genetic susceptibility to atherosclerosis

Genetic factors are implicated in atherogenesis by family and twin studies of coronary artery disease, interacting with the environment to produce the phenotypic disease. Restriction fragment length polymorphisms provide useful linkage markers with which to study the genetics of this disease, the effectiveness of marker loci being characterized in terms of their polymorphism information content. Other forms of nucleotide variation, including variable number of tandem repeats can also provide linkage markers for aetiological loci and can be detected by the use of polymerase chain amplification followed by sequencing, denaturing gel electrophoresis, base pair specific chemical cleavage or the use of oligonucleotide probes. Linkage markers may be used either in population association or familial studies. Candidate genes may be studied or complete genomic mapping attempted. A review of potential candidate genes for atherosclerosis is presented.     

Genetic damage caused by methyl-parathion in mouse spermatozoa is related to oxidative stress

Organophosphorous (OP) pesticides are considered genotoxic mainly to somatic cells, but results are not conclusive. Few studies have reported OP alterations on sperm chromatin and DNA, and oxidative stress has been related to their toxicity. Sperm cells are very sensitive to oxidative damage which has been associated with reproductive dysfunctions. We evaluated the effects of methyl-parathion (Me-Pa; a widely used OP) on sperm DNA, exploring the sensitive stage(s) of spermatogenesis and the relationship with oxidative stress. Male mice (10-12-weeks old) were administered Me-Pa (3-20 mg/kg bw/i.p.) and euthanized at 7- or 28-days post-treatment. Mature spermatozoa were obtained and evaluated for chromatin structure through SCSA (Sperm Chromatin Structure Assay; DNA Fragmentation Index parameters: Mean DFI and DFI%) and chromomycin-A(3) (CMA(3))-staining, for DNA damage through in situ-nick translation (NT-positive) and for oxidative stress through lipid peroxidation (LPO; malondialdehyde production). At 7-days post-treatment (mature spermatozoa when Me-Pa exposure), dose-dependent alterations in chromatin structure (Mean DFI and CMA(3)-staining) were observed, as well as increased DNA damage, from 2-5-fold in DFI% and NT-positive cells. Chromatin alterations and DNA damage were also observed at 28-days post-treatment (cells at meiosis at the time of exposure); suggesting that the damage induced in spermatocytes was not repaired. Positive correlations were observed between LPO and sperm DNA-related parameters. These data suggest that oxidative stress is related to Me-Pa alterations on sperm DNA integrity and cells at meiosis (28-days post-treatment) and epididymal maturation (7-days post-treatment) are Me-Pa targets. These findings suggest a potential risk of Me-Pa to the offspring after transmission.     

Genetic polymorphisms in detoxification and DNA repair genes and susceptibility to glycidamide-induced DNA damage

Acrylamide (AA) is a probable human carcinogen formed in carbohydrate-rich foodstuffs upon heating. Glycidamide (GA), the AA metabolite formed by epoxidation, is considered the ultimate genotoxic agent. In this study, the in vitro genotoxic potential of AA and GA in human whole blood leukocytes was compared using the alkaline comet assay. Although AA did not induce significant DNA damage in the concentrations tested (up to 1000 μM), GA markedly increased the percentage of tail DNA at concentrations ≥250 μM. Further, this study addressed the role of genetic polymorphisms in key genes involved in metabolism and DNA repair pathways (BER, NER, HRR, and NHEJ) on GA-induced genotoxicity assessed by the alkaline comet assay. The results obtained suggested associations between DNA damage and polymorphisms of BER (MUTYH Gln335His and XRCC1 Gln399Arg) and NER (XPC Ala499Val) genes, either alone or in combination.     

Genetic susceptibility to iatrogenic malignancy

Iatrogenic malignancies represent a devastating and often fatal long-term effect of therapy administered for a prior condition, usually a primary cancer. Earlier diagnosis and the development of more effective cancer treatments over the last 30 years have considerably improved the long-term survival of patients. However, the burgeoning number of cancer survivors has led to a parallel increase in the number of cases of iatrogenic malignancy. Consequently, understanding host susceptibility factors, such that high-risk patients can be identified, has become a priority. However, this task is made difficult by the heterogeneity of iatrogenic malignancies. Nevertheless, the identification of polymorphic loci and pathways predicted to modify dose (e.g., glutathione S-transferases, nicotinamide adenine dinucleotide phosphate: quinone oxidoreductase, cytochrome P450, and thiopurine S-methyltransferase) or determine cellular outcome (e.g., nucleotide excision DNA repair, base excision DNA repair, DNA mismatch repair, and cell death signaling) after therapy has provided insight into how host genetics may impact on the risk of developing iatrogenic malignancy.     

Genetic susceptibility to infectious diseases

The clinical outcome of infectious disease (ID) is determined by a complex interaction between microorganism, host genetic factors and environment.

Epidemiological studies have revealed differences within and between populations exposed to the same infectious agent, and in the prevalence or severity of the disease, underlying the relevance of the genetic background. Population genetic studies have estimated the genetic component (susceptibility) in the ID determination and have identified some susceptibility gene(s)/polymorphism(s).

This paper describes the methods used in genetic epidemiology. Complex segregation analysis is used to define genetic models. Parametric linkage analysis and association studies are used to identify polymorphisms strongly linked to the disease. Genome-wide scan and microarray technology are used to map and identify major genes for ID. Future developments will identify subgroups of subjects at different risks of developing ID     

妊娠期女性外阴假丝酵母菌检测及抗真菌药物敏感性分析

目的 调查女性妊娠期外阴假丝酵母菌检出情况,对引起外阴假丝酵母菌病(WC)的真菌进行鉴定及药敏试验,为临床防治提供依据.方法 采集2009年3月至2010年6月我院产科门诊产前检查的500例妊娠女性阴道分泌物进行假丝酵母菌涂片、培养,分离鉴定及药敏试验;其中涂片采用显微镜观察,培养接种于沙保弱平板,菌株鉴定采用生物梅里埃VITEK-2全自动微生物鉴定仪及配套酵母菌鉴定卡,药敏试验采用ATB FUNGUS真菌药敏条.结果 137例涂片检出芽生孢子或假菌丝,检出率为27.4%;151例培养检出假丝酵母菌,检出率为30.2%;两法综合,共192例检出假丝酵母菌,检出率为38.4%;500例中出现感染症状的VVC患者111例,感染率为22.2%;111株菌株中包括5种假丝酵母菌,以白假丝酵母菌最多,占80.2%(89株),其次为光滑假丝酵母菌,占12.6%(14株);白假丝酵母菌对伏立康唑和两性霉素B的敏感率高,分别为100.0%和94.4%,对氟康唑的敏感率低,为73.0%.结论 妊娠期女性外阴假丝酵母菌感染率较高,菌种以白假丝酵母菌为主;假丝酵母菌对氟胞嘧啶、两性霉素B、伏立康唑敏感性高,对氟康唑敏感性低;临床应普及开展对妊娠期女性外阴假丝酵母菌检测.

Abstract：

Objective To investigate the infection incidence of Candida in pregnant women and to provide evidence for prevention. Methods Candida separation, cultivation, identification and antifungal susceptibility test were performed for vulvovaginal candidiasis ( VVC). Five hundrend samples of vaginal discharge in pregnant women were collected in the department of obstetrics of our hospital from March 2009 to June 2010. Samples were detected by microscopy examination and inoculated on sabnraud medium, identified by Biomerieux VITEK-2, and antifungal susceptibility tested by ATB FUNGUS. Results Among 500 samples, 137 were positive of blastospore and pseud-ohypha (27.4% ) by microscopy examination; 192 were positive of Candidas(38.4% ) by culture. The incidence of VVC was 22. 2% . C. albicans was most frequently( 80. 2% ) isolated, followed by C. glabrata( 12. 6% ) . C. albi-cans susceptibility for voriconazole and amphotericin B were 100. 0% and 94. 4%. Fluconzazole was the lowest ( 73.0% ) . Conclusions The infection rate of vulvovaginal Candida in pregnant women is higher than that in normal people. C. albicans is the major species. Susceptibility results show that Candida infections are susceptible to 5-flucytosine, amphotericin B and voriconazole. Clinical monitor of vulvovaginal Candida infection should be strengthened.     

Rofecoxib increases susceptibility of human LDL and membrane lipids to oxidative damage: a mechanism of cardiotoxicity

Clinical investigations have demonstrated a relationship between the extended use of rofecoxib and the increased risk for atherothrombotic events. This has led to the removal of rofecoxib from the market and concern over the cardiovascular safety of other cyclooxygenase (COX)-2 selective agents. Experimental findings from independent laboratories now indicate that the cardiotoxicity of rofecoxib may not be a class effect but because of its intrinsic chemical properties. Specifically, rofecoxib has been shown to increase the susceptibility of human low-density lipoprotein and cellular membrane lipids to oxidative modification, a contributing factor to plaque instability and thrombus formation. Independently of COX-2 inhibition, rofecoxib also promoted the nonenzymatic formation of isoprostanes and reactive aldehydes from biologic lipids. The basis for these observations is that rofecoxib alters lipid structure and readily forms a reactive maleic anhydride in the presence of oxygen. By contrast, other selective (celecoxib, valdecoxib) and nonselective (naproxen, diclofenac) inhibitors did not influence rates of low-density lipoprotein and membrane lipid oxidation. We have now further confirmed these findings by demonstrating that the prooxidant activity of rofecoxib can be blocked by the potent antioxidant astaxanthin in homochiral form (all-trans 3S, 3'S). These findings provide a mechanistic rationale for differences in cardiovascular risk among COX-selective inhibitors because of their intrinsic physicochemical properties.     

Genetic determinants of susceptibility to osteoporosis

Major advances in our knowledge about the genetic determinants of osteoporosis have been made in recent years. They include the discovery of genes responsible for monogenic bone diseases associated with abnormal bone mass; the identification of quantitative trait loci for bone mass in the general population and in mice; and the characterisation of several candidate genes for osteoporosis. Information from these studies is being used to design new drugs for osteoporosis and to develop genetic markers for fracture risk assessment.     

Genetic susceptibility to adverse drug reactions

Adverse drug reactions (ADRs) are a major clinical problem. Genetic factors can determine individual susceptibility to both dose-dependent and dose-independent ADRs. Determinants of susceptibility include kinetic factors, such as gene polymorphisms in cytochrome P450 enzymes, and dynamic factors, such as polymorphisms in drug targets. The relative importance of these factors will depend on the nature of the ADR; however, it is likely that more than one gene will be involved in most instances. In the future, whole genome single nucleotide polymorphism (SNP) profiling might allow an unbiased method of determining genetic predisposing factors for ADRs, but might be limited by the lack of adequate numbers of patient samples. The overall clinical utility of genotyping in preventing ADRs needs to be proven by the use of prospective randomized controlled clinical trials.     

Genetic susceptibility to benzene toxicity in humans

Human metabolism of benzene involves pathways coded for by polymorphic genes. To determine whether the genotype at these loci might influence susceptibility to the adverse effects of benzene exposure, 208 Bulgarian petrochemical workers and controls, whose exposure to benzene was determined by active personal sampling, were studied. The frequency of DNA single-strand breaks (DNA-SSB) was determined by alkaline elution, and genotype analysis was performed for five metabolic loci. Individuals carrying the NAD(P)H:quinone oxidoreductase 1 (NQO1) variant had significantly twofold increased DNA-SSB levels compared to wild-type individuals. The same result was observed for subjects with microsomal epoxide hydrolase (EPHX) genotypes that predict the fast catalytic phenotype. Deletion of the glutathione S-transferase T1 (GSTT1) gene also showed a consistent quantitative 35-40% rise in DNA-SSB levels. Neither glutathione S-transferase M1 (GSTM1) nor myeloperoxidase (MPO) genetic variants exerted any effect on DNA-SSB levels. Combinations of two genetic polymorphisms showed the same effects on DNA-SSB as expected from the data on single genotypes. The three locus genotype predicted to produce the highest level of toxicity, based on metabolic pathways, produced a significant 5.5-fold higher level of DNA-SSB than did the genotype predicted to yield the least genotoxicity.     

Seizure susceptibility of the pregnant mouse

The effect of pregnancy on chemically-induced seizures in mice was studied. Latencies to myoclonic and clonic seizures induced by inhalation of flurothyl were significantly reduced at days 12 through 18 of gestation. Parturition resulted in a return of seizure susceptibility to control levels. The possibility that this effect might be mediated by decreased neurotransmitter levels subsequent to the decreased vitamin B₆ levels which are known to occur during pregnancy was suggested. A pregnancy-associated liver cytosolic aldehyde dehydrogenase (π-AlDH) utilized pyridoxal as a substrate, and the peak of π-AlDH activity was shown to coincide with the peak of seizure susceptibility. The activity of aldehyde oxidase, the major enzyme normally responsible for the metabolism of pyridoxal, was reduced in pregnant animals. The pyridoxal 5′-phosphate synthesizing enzymes, pyridoxal kinase and pyridoxamine phosphate oxidase, were marginally increased in activity during pregnancy. It was suggested that the increased activity of π-AlDH was indirectly responsible for the increased seizure susceptibility due to increased metabolism of pyridoxal.     

Genetic variability in susceptibility and response to toxicants

Xenobiotic metabolism is carried out by phase I and phase II enzymes which are to a large extent polymorphic. The majority of cytochrome P450 (CYP) enzymes involved in xenobiotic metabolism are polymorphic and inducible, resulting in abolished, quantitatively or qualitatively altered or enhanced drug metabolising activity. Stable duplication, multiduplication or amplification of active genes have been described. In mouse models it is apparent that inactivation of specific enzymes active in xenobiotic metabolism can affect the risk for cancer development in relation to specific xenobiotic exposure, whereas the situation in humans is far more complex. The polymorphism of CYP enzymes is expected to influence individual sensitivity and toxicity for different environmental agents, although there is as yet no real consensus in the literature about specific firm relationships in this regard. The incidence of serious and fatal adverse drug reactions (ADRs) has been found to be very high among hospitalised patients, the cost of ADRs to society is large and they are responsible for 5–10% of all hospital admissions. It is likely that predictive genotyping could avoid 10–20% of ADRs. In the present contribution an overview is presented regarding our present knowledge about the polymorphism of phase I enzymes, with emphasis on xenobiotic metabolising CYPs and the importance for metabolic activation of xenobiotics.     

Genetic susceptibility to carbamazepine-induced cutaneous adverse drug reactions

The anticonvulsant carbamazepine (CBZ) frequently causes cutaneous adverse drug reactions (cADRs), including maculopapular eruption (MPE), hypersensitivity syndrome (HSS), Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). We reported that SJS/TEN caused by CBZ is strongly associated with the HLA-B*1502 gene in Han Chinese. Here, we extended our genetic study to different types of CBZ-cADRs (91 patients, including 60 patients with SJS/TEN, 13 patients with hypersensitivity syndrome and 18 with maculopapular exanthema versus 144 tolerant controls). We used MALDI-TOF mass spectrometry to screen the genetic association of 278 single nucleotide polymorphisms (SNPs), which cover the major histocompatibility complex (MHC) region, tumor necrosis factor-alpha, heat shock protein and CBZ-metabolic enzymes, including CYP3A4, 2B6, 2C8, 2C9, 1A2 and epoxide hydrolase 1. In addition, we genotyped 20 microsatellites in the MHC region and performed HLA-typing to construct the recombinant map. We narrowed the susceptibility locus for CBZ-SJS/TEN to within 86 kb flanking the HLA-B gene on the extended B*1502 haplotype, and confirmed the association of B*1502 with SJS/TEN [Pc=1.6x10, odds ratio (OR)=1357; 95% confidence interval (CI)=193.4-8838.3]. By contrast to CBZ-SJS/TEN, HLA-B*1502 association was not observed in the MPE or HSS groups: MPE was associated with SNPs in the HLA-E region and a nearby allele, HLA-A*3101 (Pc=2.2x10, OR=17.5; 95% CI=4.6-66.5), and HSS with SNPs in the motilin gene (Pc=0.0064, OR=7.11; 95% CI=3.1-16.5) located terminal to the MHC class II genes. No SNPs in genes involved in CBZ metabolism were associated with CBZ-induced cADRs. Our data suggest that HLA-B*1502 could contribute to the pathogenesis of CBZ-SJS/TEN, and that genetic susceptibility to CBZ-induced cADRs is phenotype-specific.     

Genetic susceptibility to teratogens: state of the art

There is evidence that the susceptibility to the teratogenic effect of drugs within human populations varies extremely from one individual to another, even after identical exposures. One of the factors that may explain these interindividual differences is the genetic makeup in the pharmacokinetics and pharmacodynamics of the respective drugs. In fact, both maternal and embryonic/fetal genotypes can affect placental transport, absorption, metabolism, distribution and receptor binding of an agent, influencing its teratogenicity. We have reviewed the literature and commented on the reported correlations between genetic factors and drug-induced birth defects. There is still a clear lack of knowledge regarding this issue and the available data are often conflicting. However, the identification of specific polymorphisms associated with predisposition to teratogenesis may allow in the future the development of personalized non-teratogenic therapies for pregnant women.     

Safety considerations when prescribing immunosuppression medication to pregnant women

Introduction: In the past two decades, the number of women with autoimmune and inflammatory diseases experiencing a pregnancy has significantly increased in parallel with the enormous advances in the diagnosis and management of these disorders. However, information regarding the safety of immunosuppressive agents comes from case reports and case series and no controlled trials are available.

Areas covered: We performed a review of the literature using MEDLINE. The term ‘pregnancy’ was searched in combination with all the principal immunomodulant/immunosuppressive drugs used in rheumatic diseases.

Expert opinion: A large number of reports suggest that azathioprine, cyclosporine, hydroxychloroquine and steroids are relatively safe during pregnancy, whereas methotrexate, cyclophosphamide, mycophenolate mofetil and leflunomide are contraindicated. Data about the safety of biological agents are scant, but a growing number of publications suggest that at least TNF inhibitors could be prescribed when benefits outweigh the potential risks. Nevertheless, we cannot draw definite conclusions, as this information has not been confirmed in controlled trials. Prospective registries, some of which are already in place, are invaluable resources to answer many questions, especially on the incidence of fetal malformations. Finally, outcome studies on the offspring especially in regard to immune system and psychomotor development will shed light on long-term safety.