A gait-based paradigm to investigate central body representation in cervical dystonia patients.

BACKGROUND: Cervical dystonia (CD) is a common adult-onset idiopathic form of dystonia characterized by an abnormal head posture caused by an excessive activity of the neck muscles. The position of the head is important to direct viewpoint in the rounding environment, and the body orientation, during gait, must be coherent with the subjective straight ahead (SSA). An alteration of the SSA, as in the case of CD patients, could affect gait when visual input is not available. The aim of this study was to probe the behavior of patients with CD during blindfolded walking, investigating the ability to walk straight ahead based only on somatosensory and vestibular information. METHODS: In this observational cross-sectional study, patients with CD and healthy control subjects (HC) were compared. All participants were evaluated through a gait analysis during blindfolded walking on a GAITRite carpet, relying on their own sense of straightness. RESULTS: Patients with CD showed lower values of path length (p < 0.001), a lower number of steps on the carpet (p < 0.001). A higher number of CD patients deviated during the task, walking out of the carpet, (p < 0.005) compared to HS. No relation was found between the dystonic side and the gait trajectory deviation. A significant correlation was found between pain symptom and gait performance. CONCLUSIONS: CD patients showed dysfunctions in controlling dynamic body location during walking without visual afferences, while the dystonic side does not seem to be related to the lateral deviation of the trajectory. Our results would assume that a general proprioceptive impairment could lead to an improper body position awareness in patients with CD.

Complementemia in pregnancies with antiphospholipid syndrome.

Prognosis of pregnancies in women with antiphospholipid syndrome has dramatically improved over the past two decades using conventional treatment with low molecular weight heparin and low-dose aspirin. However, despite this regimen, 10-15% of antiphospholipid syndrome patients experience pregnancy losses. Several studies have been performed in order to identify risk factors predictive of complications. Thrombosis has been generally accepted as the key pathogenetic mechanism underlying pregnancy morbidity. However, the thrombogenic state alone is not able to explain all the different mechanisms leading to pregnancy failure. In fact, emerging evidence shows that complement pathway could play an important role in mediating clinical events in antiphospholipid syndrome. However, the exact mechanism through which complement mediates antiphospholipid syndrome complications remains unknown. Low complement levels (C3 and C4) are associated with poor pregnancy outcome in women with antiphospholipid syndrome in different studies. Hypocomplementemia could be indicated as an early predictor of adverse pregnancy outcome, available at the beginning of pregnancy for starting, if necessary, additional treatment to conventional therapy. However, future studies need to better understand the impact of low complement level on antiphospholipid syndrome pregnancy outcome.

AFM nano-mechanical study of the beating profile of hiPSC-derived cardiomyocytes beating bodies WT and DM1.

Myotonic Dystrophy type 1 (DM1) is the most common form of muscular dystrophy in adults, characterized by a variety of multisystemic features and associated with cardiac anomalies. Among cardiac phenomena, conduction defects, ventricular arrhythmias, and dilated cardiomyopathy represent the main cause of sudden death in DM1 patients. Patient-specific induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) represent a powerful in vitro model for molecular, biochemical, and physiological studies of disease in the target cells. Here, we used an Atomic Force Microscope (AFM) to measure the beating profiles of a large number of cells, organized in CM clusters (Beating Bodies, BBs), obtained from wild type (WT) and DM1 patients. We monitored the evolution over time of the frequency and intensity of the beating. We determined the variations between different BBs and over various areas of a single BB, caused by morphological and biomechanical variations. We exploited the AFM tip to apply a controlled force over the BBs, to carefully assess the biomechanical reaction of the different cell clusters over time, both in terms of beating frequency and intensity. Our measurements demonstrated differences between the WT and DM1 clusters highlighting, for the DM1 samples, an instability which was not observed in WT cells. We measured differences in the cellular response to the applied mechanical stimulus in terms of beating synchronicity over time and cell tenacity, which are in good agreement with the cellular behavior in vivo. Overall, the combination of hiPSC-CMs with AFM characterization can become a new tool to study the collective movements of cell clusters in different conditions and can be extended to the characterization of the BB response to chemical and pharmacological stimuli.

Association between false-positive TORCH and antiphospholipid antibodies in healthy pregnant women.

The present study investigated: (a) the presence of antiphospholipid antibodies and (b) the obstetric outcome in healthy pregnant women showing false-positive TORCH-Toxoplasmosis, Other: syphilis, varicella-zoster, Rubella, Cytomegalovirus (CMV), and Herpes infections-results. Data from 23 singleton healthy pregnancies with false-positive TORCH results were collected. Each woman was systematically screened for TORCH IgG and IgM during the pre-conception assessment and/or at the beginning of pregnancy. In the presence of IgM positivity, when indicated (CMV, toxoplasmosis, rubella, herpes simplex virus), IgG avidity was evaluated and, if possible, polymerase chain reaction was performed on an amniotic fluid sample in order to distinguish between primary infection or false positivity. The antiphospholipid antibodies tests were: lupus anticoagulant, anticardiolipin antibodies IgG, IgM, and anti-ß2glicoprotein I IgG, IgM. The antiphospholipid antibodies tests, if positive, were repeated after 12 weeks to confirm the results. In pregnant women with false-positive TORCH, the overall prevalence of positive antiphospholipid antibodies for one or more tests was 52.2%. To clarify the correlation of false-positive TORCH results with clinical practice, obstetric outcome was analyzed in terms of live births, week of delivery, neonatal birth weight, and neonatal birth weight percentile. A statistically significant lower neonatal birth weight and neonatal birth weight percentile were observed in women with false-positive TORCH associated with antiphospholipid antibodies positivity (Group A) in comparison with those in women with false-positive TORCH without antiphospholipid antibodies positivity (Group B). No statistically significant difference was found for the week of delivery between the two groups. It is hoped that future studies will verify the life-long persistence of antiphospholipid antibodies positivity by follow-up of these women and identify who will develop a classical antiphospholipid syndrome or other autoimmune disorders.

Perception of dental students on risk factors of musculoskeletal disorders.

OBJECTIVE: To evaluate the validity and reliability of the Job Factors Questionnaire, and the influence of gender, academic level and pain/discomfort on dental students' perception regarding risk factors of musculoskeletal disorders. METHODS: One hundred forty-five dental students from Stony Brook School of Dental Medicine participated voluntarily in this study. The survey was organised in two sections: (i) Job Factors Questionnaire with 15 items that evaluated students' perceptions about job/study environmental risk factors and their potential contribution to musculoskeletal disorders. The tri-factorial structure (repetitiveness, work posture and external factors) was used; (ii) Part of the Nordic Questionnaire with questions referring to 9 body areas: Neck, shoulders, upper back, elbows, lower back, wrists/hands, hips, knees and ankles/feet. Students answered if they have had a job-related pain/discomfort in any of these body areas in the previous 12 months. The data were evaluated statistically by confirmatory factor analysis, convergent and discriminant validities, internal consistency and Z-test (α = .05). RESULTS: The tri-factorial structure was considered valid and reliable for the sample after excluding item 8 and inserting correlations between items 11 and 12, and between 14 and 15. The academic level presented a significant effect on the factors "Work Posture" (P = .02) and "External Factors" (P = .01). Most of the students reported pain in their neck (73.79%), lower back (62.06%) and shoulders (53.10%) in the previous 12 months. CONCLUSION: The Work Posture and External Factors were influenced only by academic level. The lower the students' academic level, the higher their perception for both factors of musculoskeletal disorders.

Myotonic dystrophy type 1: role of CCG, CTC and CGG interruptions within DMPK alleles in the pathogenesis and molecular diagnosis.

Myotonic dystrophy type 1 (DM1) is a multisystem neuromuscular disease caused by a CTG triplet expansion in the 3'-untranslated region (3'-UTR) of DMPK gene. This CTG array is usually uninterrupted in both healthy and DM1 patients, but recent studies identified pathological variant expansions containing unstable CCG, CTC and CGG interruptions with a prevalence of 3-5% of cases. In this review, we will describe the clinical, molecular and genetic issues related to the occurrence of variant expansions associated with DM1. Indeed, the identification of these complex DMPK alleles leads to practical consequences in DM1 genetic counseling and testing, because these exams can give false negative results. Moreover, DM1 patients carrying interrupted alleles can manifest either additional atypical neurological symptoms or, conversely, mild, late-onset forms. Therefore, the prognosis of the disease in these patients is difficult to determine because of the great uncertainty about the genotype-phenotype correlations. We will discuss the putative effects of the variant DM1 alleles on the pathogenic disease mechanisms, including mitotic and meiotic repeats instability and splicing alteration typical of DM1 tissues. Interruptions within the DMPK expanded alleles could also interfere with the chromatin structure, the transcriptional activity of the DM1 locus and the interaction with RNA CUG-binding proteins.

Cerebral sinovenous thrombosis in neonatal antiphospholipid syndrome: a new entity?

Neonatal antiphospholipid syndrome (neonatal APS) seems to be exceedingly rare, as the antiphospholipid antibodies (aPL) related thrombosis in the neonatal period. The pathogenesis of perinatal aPL related thrombosis may be explained both by the transplacental passage of the maternal antibodies and by the production of de novo antibodies by the neonate. However, few cases of neonatal APS are reported in the literature, especially regarding arterial thrombotic events. In particular, only two cases of neonatal aPL related isolated cerebral sinovenous thrombosis (CSVT) are described in the literature. Despite its frequency, CSVT results in significant mortality and morbidity, probably also due to the difficulty in early diagnosis and then in correct managing in the neonatal period. A diagnosis of neonatal APS should be considered in the evaluation of neonates with CSVT, as well as in any case of neonatal thrombosis, to correctly manage the affected neonates and counsel the mother for future pregnancies.

Plasma heavy metal levels correlate with deregulated gene expression of detoxifying enzymes in osteoporotic patients.

Heavy metal levels appear to be associated with low bone mineral density (BMD) and the consequent osteoporosis risk, but the relationship with the disease has not been clearly defined. The altered expression pattern of numerous genes, including detoxifying genes, seems to play a pivotal role in this context, leading to increased susceptibility to several diseases, including osteoporosis. The purpose of this study is to analyse circulating heavy metals levels and the expression of detoxifying genes in osteoporotic patients (OPs, n = 31), compared with healthy subjects (CTRs, n = 32). Heavy metals concentration in plasma samples was determined by Inductively Coupled Plasma Mass Spectrometry (ICP-MS), and the subsequent expression analysis of NAD(P)H quinone dehydrogenase 1 (NQO1), Catalase (CAT), and Metallothionein 1E (MT1E) genes in Peripheral Blood Mononuclear Cells (PBMCs) was assessed by real-time polymerase chain reaction (qRT-PCR). Copper (Cu), mercury (Hg), molybdenum (Mo) and lead (Pb) were found to be significantly higher in the plasma of OPs compared to CTRs. Analysis of the expression levels of detoxifying genes showed a significant decrease in CAT and MT1E in OP group. In addition, Cu correlated positively with the expression levels of both CAT and MT1E in CTRs group and MT1E in OPs. This study shows an increased circulating concentration of certain metals combined with an altered expression pattern of detoxifying genes in OPs, highlighting a novel aspect to be investigated in order to better characterize the role of metals in the pathogenesis of osteoporosis.

Aberrant splicing and expression of the non muscle myosin heavy-chain gene MYH14 in DM1 muscle tissues.

Myotonic dystrophy type 1 (DM1) is a complex multisystemic disorder caused by an expansion of a CTG repeat located at the 3' untranslated region (UTR) of DMPK on chromosome 19q13.3. Aberrant messenger RNA (mRNA) splicing of several genes has been reported to explain some of the symptoms of DM1 including insulin resistance, muscle wasting and myotonia. In this paper we analyzed the expression of the MYH14 mRNA and protein in the muscle of DM1 patients (n=12) with different expansion lengths and normal subjects (n=7). The MYH14 gene is located on chromosome 19q13.3 and encodes for one of the heavy chains of the so called class II "nonmuscle" myosins (NMHCII). MYH14 has two alternative spliced isoforms: the inserted isoform (NMHCII-C1) which includes 8 amino acids located in the globular head of the protein, not encoded by the non inserted isoform (NMHCII-C0). Results showed a splicing unbalance of the MYH14 gene in DM1 muscle, with a prevalent expression of the NMHCII-C0 isoform more marked in DM1 patients harboring large CTG expansions. Minigene assay indicated that levels of the MBNL1 protein positively regulates the inclusion of the MYH14 exon 6. Quantitative analysis of the MYH14 expression revealed a significant reduction in the DM1 muscle samples, both at mRNA and protein level. No differences were found between DM1 and controls in the skeletal muscle localization of MYH14, obtained through immunofluorescence analysis. In line with the thesis of an "RNA gain of function" hypothesis described for the CTG mutation, we conclude that the alterations of the MYH14 gene may contribute to the DM1 molecular pathogenesis.

The relationship between TORCH complex false positivity and obstetric outcome in patients with antiphospholipid syndrome.

OBJECTIVE: The presence of TORCH IgM positivity is not a specific indicator of primary infection; the assessment of IgG avidity index has been shown to be useful in identifying or excluding primary infection in pregnant women with no pre-gestational TORCH serology. TORCH is an acronym for Toxoplasmosis, Others (HBV, syphilis, Varicella-Zoster virus, Epstein Barr virus, Coxsackie virus and Parvovirus), Rubella, Cytomegalovirus (CMV) and Herpes Simplex. PATIENTS AND METHODS: Data from 54 pregnancies in women with antiphospholipid syndrome (APS) were assessed in comparison with data from 222 healthy pregnant women as controls. Each woman in both groups was systematically screened for TORCH IgG and IgM during pre-conceptional evaluation and/or at the beginning of pregnancy. The assessment of IgG avidity was also evaluated in order to identify primary infection or false positivity. RESULTS: A significant increase of CMV IgM false positivity in APS in comparison with controls was detected. A worse pregnancy outcome was observed among APS patients having CMV IgM false positivity in comparison with APS patients without false positivity; in particular a statistically significant lower neonatal birth weight and a lower neonatal birth weight percentile were observed. CONCLUSION: Our data suggest that the presence of CMV IgM false positivity could represent a novel prognostic factor for poor pregnancy outcome in APS patients.

Complementemia and obstetric outcome in pregnancy with antiphospholipid syndrome.

OBJECTIVE: To investigate the predictive value of serum C3 and C4 complement component levels in relation to pregnancy outcome in patients with antiphospholipid syndrome (APS). MATERIALS AND METHODS: A prospective study of 47 pregnancies associated with APS was performed. Pregnancy outcome was analyzed in terms of: fetal loss, preterm delivery (≤34 gestational weeks), fetal intrauterine growth restriction (IUGR), birth weight <2500 g and preeclampsia. Week at delivery, neonatal birth weight and neonatal birth weight percentile were also investigated. Hypocomplementemia, positivity for anti-dsDNA and triple positivity for antiphospholipid antibodies (aPL) were related to pregnancy outcome. RESULTS: Forty-three pregnancies ended in live births with a fetal loss rate of 8.5%. Fetal death, preterm delivery and birth weight <2500 g were associated with hypocomplementemia (p = 0.019, p = 0.0002, p < 0.0001 respectively). Lower neonatal birth weight, lower neonatal birth weight percentile and lower week at delivery were associated with hypocomplementemia (p < 0.0001, p = 0.0003, p < 0.0001 respectively) and with triple aPL positivity (p = 0.008, p = 0.014, p = 0.03 respectively). A poor pregnancy outcome was confirmed among primary APS (PAPS) pregnancies with hypocomplementemia. Multivariate analysis confirmed that hypocomplementemia was an independent predictor of lower neonatal birth weight (p = 0.0001) and lower week at delivery (p = 0.002). CONCLUSION: Hypocomplementemia could be considered a novel prognostic factor for pregnancy outcome in APS patients.

Early subclinical cochlear dysfunction in myotonic dystrophy type 1.

BACKGROUND: Myotonic dystrophy type 1 (DM1) is an autosomal-dominant inherited disorder clinically characterized by variable systemic manifestations. Among clinical features of the disease, 'precocious presbyacusis' has been previously reported. The underlying mechanism of this auditory impairment remains still poorly understood. Hearing is an active process located in the cochlea, where the outer hair cells (OHCs) play an important role in sound perception through a 'contractile' like movement resembling skeletal muscle fibers dynamics. OHCs status has not yet been investigated in DM1 patients. OHCs integrity can be assessed by measuring transient-evoked otoacoustic emissions (TEOAE), a non-invasive, repeatable, and objective quantitative tool. METHODS: We recruited 25 patients with a genetically confirmed diagnosis of DM1, and 28 age-matched control subjects. All of them underwent a routine audiological evaluation and TEOAE recordings. RESULTS: We detected a high prevalence of sensorineural high-frequency hearing loss (HFHL) in DM1 patients, significantly different if compared to control subjects. Interestingly, the accurate analysis of DM1 recorded data showed a marked impairment of TEOAE both in HFHL+ and unexpectedly in HFHL- group. Cochlear dysfunction was restricted to frequencies above 2000 Hz in the HFHL- group, but it extended to 1000 Hz in HFHL+ DM1 patients. CONCLUSIONS: Our study indicates that cochlear impairment in DM1 is present, even in patients without evidence of hearing loss at a standard audiometric analysis. Hence, in the current clinical practice, an assessment of cochlear function by TEOAE recording may be useful in DM1 patients to identify precocious signs of cochlear dysfunction.

The myotonic dystrophy type 2 (DM2) gene product zinc finger protein 9 (ZNF9) is associated with sarcomeres and normally localized in DM2 patients' muscles.

AIMS: Myotonic dystrophy type 2 (DM2) is caused by a [CCTG]n intronic expansion in the zinc finger protein 9 (ZNF9) gene. As for DM1, sharing with DM2 a similar phenotype, the pathogenic mutation involves a transcribed but untranslated genomic region, suggesting that RNA toxicity may have a role in the pathogenesis of these multisystem disorders by interfering with common cellular mechanisms. However, haploinsufficiency has been described in DM1 and DM2 animal models, and might contribute to pathogenesis. The aim of the present work was therefore to assess ZNF9 protein expression in rat tissues and in human muscle, and ZNF9 subcellular distribution in normal and DM2 human muscles. METHODS: Polyclonal anti-ZNF9 antibodies were obtained in rabbit, high pressure liquid chromatography-purified, and used for Western blot, standard and confocal immunofluorescence and immunogold labelling electron microscopy on a panel of normal rat tissues and on normal and DM2 human muscles. RESULTS: Western blot analysis showed that ZNF9 is ubiquitously expressed in mammalian tissues, and that its signal is not substantially modified in DM2 muscles. Immunofluorescence studies showed a myofibrillar distribution of ZNF9, and double staining with two non-repetitive epitopes of titin located it in the I bands. This finding was confirmed by the visualization of ZNF9 in close relation with sarcomeric thin filaments by immunogold labelling electron microscopy. ZNF9 distribution was unaltered in DM2 muscle fibres. CONCLUSIONS: ZNF9 is abundantly expressed in human myofibres, where it is located in the sarcomeric I bands, and no modification of this pattern is observed in DM2 muscles.

False-positive IgM for CMV in pregnant women with autoimmune disease: a novel prognostic factor for poor pregnancy outcome.

Our aims were to assess the frequency of false-positive IgM antibodies for cytomegalovirus in pregnant women with autoimmune diseases and in healthy women (controls) and to determine their relationship with pregnancy outcome. Data from 133 pregnancies in 118 patients with autoimmune diseases and from 222 pregnancies in 198 controls were assessed. When positive IgM for cytomegalovirus was detected, IgG avidity, cytomegalovirus isolation and polymerase chain reaction for CMV-DNA in maternal urine and amniotic fluid samples were performed in order to identify primary infection or false positivity. A statistically significantly higher rate of false-positive IgM was found in pregnancies with autoimmune diseases (16.5%) in comparison with controls (0.9%). A worse pregnancy outcome was observed among patients with autoimmune disease and false cytomegalovirus IgM in comparison with those without false positivity: earlier week of delivery (p = 0.017), lower neonatal birth weight (p = 0.0004) and neonatal birth weight percentile (p = 0.002), higher rate of intrauterine growth restriction (p = 0.02) and babies weighing less than 2000 g (p = 0.025) were encountered. The presence of false cytomegalovirus IgM in patients with autoimmune diseases could be used as a novel prognostic index of poor pregnancy outcome: it may reflect a non-specific activation of the immune system that could negatively affect pregnancy outcome. Lupus (2010) 19, 844-849.

A pilot study of lncRNAs expression profile in serum of progressive multiple sclerosis patients.

OBJECTIVE: Multiple Sclerosis (MS) is an inflammatory and neurodegenerative disease that affect both white and gray matter. The relapsing and the eventually progressive course of MS is heterogeneous; thus, a confident long-term prediction of individual prognosis is not possible yet. Recent studies have demonstrated the role of long non-coding RNA (lncRNAs) as potential biomarkers that could provide information to predict disease activity and progression. PATIENTS AND METHODS: By qRT-PCR, we analysed the lncRNAs expression in the serum of 16 secondary progressive MS (SP-MS), 12 primary progressive (PP-MS) patients and 8 healthy controls. RESULTS: We found that TUG1 was upregulated in SP-MS, while the comparison of PP-MS vs. controls showed a downregulation of non-protein coding RNA 188 (LRRC75A-AS1) and a significant upregulation of two lncRNAs: long intergenic non-protein coding RNA 293 (LINC00293) and RP11-29G8.3. Moreover, we performed an in-silico analysis using DIANA-LncBase v2 and HMDD v3.0 software, in order to predict the possible interaction of these four lncRNAs with miRNAs. We identified 21 miRNAs prediction targets possibly involved in MS. CONCLUSIONS: Our data indicate a regulatory function of these lncRNAs in autoimmune and inflammatory processes related to MS suggesting their potential role in progressive MS pathogenesis.

The CTG repeat expansion size correlates with the splicing defects observed in muscles from myotonic dystrophy type 1 patients.

BACKGROUND: Myotonic dystrophy type 1 is caused by an unstable (CTG)n repetition located in the 3'UTR of the DM protein kinase gene (DMPK). Untranslated expanded DMPK transcripts are retained in ribonuclear foci which sequester CUG-binding proteins essential for the maturation of pre-mRNAs. AIM: To investigate the effects of CTG expansion length on three molecular parameters associated with the DM1 muscle pathology: (1) the expression level of the DMPK gene; (2) the degree of splicing misregulation; and (3) the number of ribonuclear foci. METHODS: Splicing analysis of the IR, MBNL1, c-TNT and CLCN1 genes, RNA-FISH experiments and determination of the DMPK expression on muscle samples from DM1 patients with an expansion below 500 repetitions (n = 6), DM1 patients carrying a mutation above 1000 CTGs (n = 6), and from controls (n = 6). RESULTS: The level of aberrant splicing of the IR, MBNL1, c-TNT and CLCN1 genes is different between the two groups of DM1 muscle samples and correlates with the CTG repeat length. RNA-FISH analysis revealed that the number of ribonuclear foci in DM1 muscle sections increases in patients with a higher (CTG)n number. No relationships were found between the expression level of the DMPK gene transcript and average expansion sizes. CONCLUSION: The CTG repeat length plays a key role in the extent of splicing misregulation and foci formation, thus providing a useful link between the genotype and the molecular cellular phenotype in DM1.

Micronuclei frequency in peripheral blood lymphocytes of cancer patients: a meta-analysis.

Micronuclei (MN) frequency is a biomarker of chromosomal damage, genome instability, and cancer risk that integrates acquired mutations and genetic susceptibility. To evaluate and summarize the evidence reporting association between cancer and MN formation, we performed a meta-analysis assessing the frequency of this biomarker in cancer patients. Findings from 37 publications were retrieved through an extensive search of the MedLine/PubMed database. Given the heterogeneity of the study design, all studies were re-classified into three groups: (i) baseline MN frequency of untreated cancer patients (25 studies), (ii) induced MN frequency in thyroid cancer patients undergoing radioiodine treatment (9 studies), and (iii) radiosensitivity of lymphocytes (12 studies) in untreated cancer patients. A meta-estimate of the frequency ratio (meta-FR) was computed in each group. A significant increase of MN frequency was found in untreated cancer patients (meta-FR=1.45; 95% Confidence Interval (95% CI): 1.28-1.64) and in thyroid cancer patients after radioiodine treatment (meta-FR=2.26; 95% CI: 1.90-2.68). The third meta-analysis showed a negative trend of meta-FR's when plotted vs. the dose used to study patients' radiosensitivity, possibly associated to a high rate of apoptosis. The results of this review substantiate the existing evidence about a role of MN in various steps of carcinogenesis. The relatively small numbers of papers suitable for the meta-analysis call for new and larger studies, possibly based on high-throughput techniques, to further understand the role of MN formation in the occurrence of genetic instability and cancer.

Genetic polymorphisms and micronucleus formation: a review of the literature.

The formation of micronuclei (MN) is extensively used in molecular epidemiology as a biomarker of chromosomal damage, genome instability, and eventually of cancer risk. The occurrence of MN represents an integrated response to chromosome-instability phenotypes and altered cellular viabilities caused by genetic defects and/or exogenous exposures to genotoxic agents. The present article reviews human population studies addressing the relationship between genetic polymorphisms and MN formation, and provides insight into how genetic variants could modulate the effect of environmental exposures to genotoxic agents, host factors (gender, age), lifestyle characteristics (smoking, alcohol, folate), and diseases (coronary artery disease, cancer). Seventy-two studies measuring MN frequency either in peripheral blood lymphocytes or exfoliated cells were retrieved after an extensive search of the MedLine/PubMed database. The effect of genetic polymorphisms on MN formation is complex, influenced to a different extent by several polymorphisms of proteins or enzymes involved in xenobiotic metabolism, DNA repair proteins, and folate-metabolism enzymes. This heterogeneity reflects the presence of multiple external and internal exposures, and the large number of chromosomal alterations eventually resulting in MN formation. Polymorphisms of EPHX, GSTT1, and GSTM1 are of special importance in modulating the frequency of chromosomal damage in individuals exposed to genotoxic agents and in unexposed populations. Variants of ALDH2 genes are consistently associated with MN formation induced by alcohol drinking. Carriers of BRCA1 and BRCA2 mutations (with or without breast cancer) show enhanced sensitivity to clastogens. Some evidence further suggests that DNA repair (XRCC1 and XRCC3) and folate-metabolism genes (MTHFR) also influence MN formation. As some of the findings are based on relatively small numbers of subjects, larger scale studies are required that include scoring of additional endpoints (e.g., MN in combination with fluorescent in situ hybridization, analysis of nucleoplasmic bridges and nuclear buds), and address gene-gene interactions.

Analysis of Single Nucleotide Polymorphisms (SNPs) of the small-conductance calcium activated potassium channel (SK3) gene as genetic modifier of the cardiac phenotype in myotonic dystrophy type 1 patients.

Myotonic dystrophy type 1 (DM1) is the most frequently inherited neuromuscular disease in adults. It is a multisystemic disorder with major cardiac involvement most commonly represented by first-degree atrioventricular heart block (AVB), followed by different degrees of bundle-branch and intraventricular blocks In search for candidate genes, modifiers of the AVB phenotype in DM1, the expression of the small-conductance calcium activated potassium channel (SK3) gene was analysed in muscle biopsies from DM1 patients. The association between SK3 polymorphisms and the AVB phenotype was then studied analyzing 40 DM1 patients with AVB and 40 age-matched DM1 affected individuals with no ECG abnormalities. [CTG]n repeat length and cardiac clinical picture were also assessed for correlation. QRT-PCR experiments showed an over-expression of the SK3 transcript in DM1 muscle biopsies compared to healthy controls. However, no statistical association between the AVB phenotype and either the [CTG]n expansion length or the presence of specific SNPs in the SK3 gene were detected. These findings suggest that modifier genes, other than SK3, should be identified in order to explain the cardiac phenotypic variability among DM1 patients.

[Urinary 8-hydroxy-2'-deoxyguanosine: a biomarker of environmental oxidative stress?]. / Dosage de la 8-hydroxy-2'-deoxyguanosine dans les urines: un biomarqueur du stress oxydatif d'origine environnementale?

The oxidative stress plays an important role in certain pathologies, notably in carcinogenesis. Indeed, reactive oxygen species (ROS) can induce a variety of damage to DNA, including oxidized bases which will then be repaired and eliminated in urine. The 8-hydroxy-2'-deoxyguanosine (8-OHdG), the most frequent member of these oxidized bases, can be measured in DNA or in urine by various methods. The urinary measurement was used in several studies among subjects with occupational or environmental exposure. Diverse chemical or physical agents can indeed contribute to the increase of oxidative stress, although the latter has several origins. Our objective is to analyze through these studies the interest, the limits and the implementation of this biomarker. The majority of the studies reveal an increase of the concentration of 8-OHdG in urine in exposed subjects (polycyclic aromatic hydrocarbons, metals, ionizing radiation and other agents) compared with controls or according to exposure levels. The urinary concentration of 8-OHdG is subject to important inter and intra-individual variations. The biomonitoring studies have to take into account diverse confounding factors, which may have conflicting effects. Moreover the results strongly depend on the analytical method used. Thus other investigations are necessary to validate this biomarker and better know its sources of variability, its biological significance, its dose-response relationship and its kinetics after exposure to oxidative stress agents.