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Oxygen, an essential molecule for aerobic life, can be the cause of oxidative stress, resulting from a breakdown of the equilibrium between pro-oxidant systems (mitochondrial respiratory chain, ionizing radiation, etc.) and antioxidant systems (superoxide dismutase, glutathione peroxidase, catalase, vitamins, trace elements, etc.). Reactive oxygen species, mediators of oxidative stress, are very unstable chemicals that seek to stabilize by reacting with different biological molecules, resulting in irreversible damage to lipids, carbohydrates, proteins and nucleic acids. Reactive oxygen species are thus involved in many pathologies that can be alleviated by nutritional supplementation with antioxidants. This synthesis summarizes the reactive oxygen species production mechanisms, their effects on biological targets and their involvement in autoimmune diseases, body-specific defense systems, assessment of the oxidative stress status and possible antioxidant therapies. [ABSTRACT FROM AUTHOR]

Copyright of Biologie Aujourd'hui is the property of EDP Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Résumé: CRISPR-Cas est décrit comme un système immunitaire adaptatif qui permet aux bactéries et aux archées de se défendre contre les agressions virales. La technologie dérivée de ces systèmes CRISPR-Cas, qui permet de cliver précisément une séquence génomique, est désormais la base de puissants outils de biologie moléculaire et d'édition des génomes. Les « ciseaux moléculaires » CRISPR-Cas utilisent des endonucléases Cas, programmées et activées avec un ARN guide, pour couper spécifiquement une séquence cible ARN ou ADN. Certaines de ces enzymes Cas, notamment Cas12a et Cas13a, présentent au-delà de cette activité de coupure dirigée par un guide ARN, une activité générique de clivage collatéral en trans de toutes séquences nucléiques rencontrées. Ces différentes activités des systèmes CRISPR-Cas ont pu être exploitées pour développer des outils prometteurs de diagnostic moléculaire. Si les applications sont très nombreuses dans différents domaines, nous proposons ici d'illustrer le potentiel de ces approches basées sur CRISPR-Cas dans le cadre du diagnostic en virologie. CRISPR-Cas is an adaptive immune system that prevents bacteria and archea from nucleic acids invasion such as viral genomes. The ability of the CRISPR-Cas technology to effectively and precisely cut a targeted genomic DNA region was exploited to develop powerful genome editing tools that were adapted for a wide range of applications, revolutionizing biological sciences. The CRISPR-Cas system consists of a Cas endonuclease triggered by a RNA guide for highly specific cleavage of targeted DNA or RNA sequences. In addition to the target specific cleavage, some Cas enzymes, including Cas12a and Cas13a, display a collateral trans-cleavage activity that allows the cleavage of all surrounding single-stranded nucleic acids. These biosensing activities of CRISPR-Cas systems, based on target specific binding and cleavage, are promising tools to develop accurate diagnostic methods to detect specific nucleic acids. CRISPRCas could therefore be used to diagnose a wide variety of diseases. In the current review we propose to describe the more significant advances for virus detection based on CRISPR-Cas systems. [ABSTRACT FROM AUTHOR]

Despite many advances in assisted reproductive technologies (ART), only 10-15% of the embryos replaced give birth to a child. Some of the failures are directly attributable to the embryo itself, but the main limiting factor is the implantation failure, often associated with desynchronizations of dialogue between embryonic and maternal tissue. Over the past decade, Omics techniques (high-throughput techniques) have been widely used in the fertility field. Notably, the study of circulating nucleic acids (microRNAs, free DNA) has been the subject of important scientific and medical advances. Indeed, they currently occupy a primordial place as biomarkers of interest in human pathology, especially in cancer. Easily accessible in biological fluids or in the embryonic culture medium, they represent tools of choice in ART for the development of new noninvasive diagnostic and prognostic tests. The use of these biomarkers both in the assessment of the ovary reserve, embryonic quality and in the prevention of implantation failures, corresponds to an innovative and extremely promising approach in the field. On the other hand, Omics techniques have enabled major advances in the identification of endometrial receptivity biomarkers, which have therefore allowed the establishment of an endometrial receptivity test, prompting practitioners to revisit their practices. [ABSTRACT FROM AUTHOR]

Despite their toxicity, DNA alkylating drugs remain a cornerstone of anticancer therapy. The classical thinking was that rapidly dividing tumour cells left more of its DNA in an exposed single-stranded state, making these rapidly dividing cells more susceptible to alkylating drugs. As our understanding of DNA repair pathways has matured it is becoming clear that compromised DNA repair – a hallmark of cancer – plays a role as well in defining the therapeutic window of these toxic drugs. Hence, although new alkylating motifs are unlikely to progress through the clinic, the legacy of these medicines is that we now understand the therapeutic potential of targeting DNA damage repair pathways. Here we look at the history of alkylating agents as anticancer drugs, while also summarizing the different mechanistic approaches to covalent DNA modification. We also provide several case studies on how insights into compromised DNA repair pathways are paving the way for potent and less toxic targeted medicines against the DNA damage response.

In the late 1860s, DNA was first identified by the Swiss physician and biochemist Friedrich Miescher. Since this time, we have solved its structure, learned how DNA divides in our cells, and elucidated molecular mechanisms for the transmission of our hereditary information. Fundamental to all these discoveries is the ability to extract our DNA in high purity. In laboratories today, DNA extraction is a routine practice performed from readily available commercial kits. However, in the late 1800s, DNA extraction was an emerging method that required tedious laboratory approaches.

A key aspect of antiviral immunity is the distinction between "self" and "non-self" components. This distinction can be established through the detection of double-stranded RNA (dsRNA), a common sign of viral infection, by cytosolic RNA helicases. Depending on the organism, two major antiviral pathways can be induced by dsRNA helicases: RNA interference (RNAi) and interferon (IFN) signaling. In the RNAi pathway, dsRNAs are recognized by a Dicer protein, and are then used for the sequence-dependent recognition and subsequent degradation of the complementary viral RNAs. In the IFN signaling pathway, dsRNAs are recognized by a RIG-like receptor (RLR), which induces a signaling cascade in order to induce the expression of IFNs, cytokines and chemokines. In this review, we discuss the RNA features that can be used by the cell to detect a viral infection, the two aforementioned types of helicase-mediated sensing, as well as some viral escape mechanisms developed to avoid recognition. [ABSTRACT FROM AUTHOR]

Résumé: Un élément clé de l'immunité antivirale est la distinction entre les éléments du « soi » et du « non-soi ». Cette distinction peut être effectuée à travers la détection d'ARN double-brin (ARNdb), un signe courant d'infection virale, notamment par des hélicases ARN cytosoliques. Selon l'organisme, deux voies antivirales majeures peuvent être induites par des hélicases agissant sur l'ARN : la voie de l'ARN interférence et celle des interférons (IFN). Dans la voie de l'ARN interférence, les ARNdb sont détectés par une protéine Dicer, puis guident la reconnaissance séquence-dépendante et la dégradation subséquente de l'ARN viral complémentaire. Dans la voie de signalisation IFN, les ARNdb sont reconnus par un récepteur RIG- like (RLR), conduisant à l'expression d'IFNs, de cytokines et de chimiokines. Dans cette revue, nous abordons les caractéristiques des ARN qui peuvent être utilisées par la cellule afin de détecter une infection virale, les deux types de reconnaissance par des hélicases mentionnées plus haut, ainsi que certains mécanismes d'échappement qui permettent aux virus d'éviter la détection. A key aspect of antiviral immunity is the distinction between "self" and "non-self" components. This distinction can be established through the detection of double-stranded RNA (dsRNA), a common sign of viral infection, by cytosolic RNA helicases. Depending on the organism, two major antiviral pathways can be induced by dsRNA helicases: RNA interference (RNAi) and interferon (IFN) signaling. In the RNAi pathway, dsRNAs are recognized by a Dicer protein, and are then used for the sequence-dependent recognition and subsequent degradation of the complementary viral RNAs. In the IFN signaling pathway, dsRNAs are recognized by a RIG-like receptor (RLR), which induces a signaling cascade in order to induce the expression of IFNs, cytokines and chemokines. In this review, we discuss the RNA features that can be used by the cell to detect a viral infection, the two aforementioned types of helicase-mediated sensing, as well as some viral escape mechanisms developed to avoid recognition. [ABSTRACT FROM AUTHOR]

DNA replication is an extremely complex process, involving thousands of replication forks progressing along chromosomes. These forks are frequently slowed down or stopped by various obstacles, such as secondary DNA structures, chromatin-acting proteins or a lack of nucleotides. This slowing down, known as replicative stress, plays a central role in tumour development. Complex processes, which are not yet fully understood, are set up to respond to this stress. Certain nucleases, such as MRE11 and DNA2, degrade the neo-replicated DNA at the level of blocked forks, allowing the replication to restart. The interferon pathway is a defense mechanism against pathogens that detects the presence of foreign nucleic acids in the cytoplasm and activates the innate immune response. DNA fragments resulting from genomic DNA metabolism (repair, retrotransposition) can diffuse into the cytoplasm and activate this pathway. A pathological manifestation of this process is the Aicardi-Goutières syndrome, a rare disease characterized by chronic inflammation leading to neurodegenerative and developmental problems. In this encephalopathy, it has been suggested that DNA replication may generate cytosolic DNA fragments, but the mechanisms involved have not been characterized. SAMHD1 is frequently mutated in the Aicardi-Goutières syndrome as well as in some cancers, but its role in the etiology of these diseases was largely unknown. We show that cytosolic DNA accumulates in SAMHD1-deficient cells, particularly in the presence of replicative stress, activating the interferon response. SAMHD1 is important for DNA replication under normal conditions and for the processing of stopped forks, independent of its dNTPase activity. In addition, SAMHD1 stimulates the exonuclease activity of MRE11 in vitro. When SAMHD1 is absent, degradation of neosynthesized DNA is inhibited, which prevents activation of the replication checkpoint and leads to failure to restart the replication forks. Resection of the replication forks is performed by an alternative mechanism which releases DNA fragments into the cytosol, activating the interferon response. The results obtained show, for the first time, a direct link between the response to replication stress and the production of interferons. These results have important implications for our understanding of the Aicardi-Goutières syndrome and cancers related to SAMHD1. For example, we have shown that MRE11 andRECQ1 are responsible for the production of DNA fragments that trigger the inflammatory response in cells deficient for SAMHD1. We can therefore imagine that blocking the activity of these enzymes could decrease the production of DNA fragments and, ultimately, the activation of innate immunity in these cells. In addition, the interferon pathway plays an essential role in the therapeutic efficacy of irradiation and certain chemotherapeutic agents such as oxaliplatin. Modulating this response could therefore be of much wider interest in anti-tumour therapy. [ABSTRACT FROM AUTHOR]

Exploring the spatiotemporal dynamics of biomolecules on a single-molecule level requires innovative ways to make them spectroscopically visible. Fluorescence resonance energy transfer (FRET) uses a pair of organic dyes as reporters to measure distances along a predefined biomolecular reaction coordinate. For this nanoscopic ruler to work, the fluorescent labels need to be coupled onto the molecule of interest in a bioorthogonal and site-selective manner. Tagging large non-coding RNAs with single-nucleotide precision is an open challenge. Here we summarize current strategies in labeling riboswitches and ribozymes for fluorescence spectroscopy and FRET in particular. A special focus lies on our recently developed, DNA-guided approach that inserts two fluorophores through a stepwise process of templated functionality transfer and click chemistry.

The search for effective drugs against cisplatin-resistant tumors resulted in a large number of organometallic compounds that are evaluated for their antiproliferative activity. Among the most promising candidates are bent metallocenes based on various transition metal ions and ligands. The elucidation of structural features and the characterization of the interaction of a drug candidate with its target require accurate and sensitive analytical tools. Tandem mass spectrometry is applied to the investigation of the adduct sites and binding patterns of metallodrugs bound to single-stranded oligonucleotides and higher-order nucleic acids. Results reveal the binding specificities of the different metallodrugs and demonstrate the influence they exert on the dissociation pathways of the adducts in the gas-phase.

Oligonucleotides are small nucleic acids capable of interacting with DNA or RNA to modulate gene expression. Widely used by researchers as research tools to modulate the expression of the genes they seek to decipher the function, oligonucleotides can also serve as therapeutic agents to regulate targets of interest. After the first marketing authorisation of an oligonucleotide therapeutics in 1998, the field met little clinical success until 2016 when Spinraza® became the first drug authorized for spinal muscular atrophy. This compound became in the following years the first "blockbuster" among this class of molecules, validating the commercial potential of oligonucleotide drugs. Since then, about ten other oligonucleotides hit the market and a broad pipeline is currently in late clinical development. Through our article, we describe therapeutic oligonucleotides, their modes of action and their patentability., (© 2023 médecine/sciences – Inserm.)

Despite a recent explosion of interest in G-quadruplex DNA, most fundamental questions regarding the possible presence and function of these intriguing structures in vivo remain unanswered. Cell-permeable G-quadruplex specific probes should provide researchers with new tools for studying these alternately folded DNA structures and their potential involvement in gene expression, chromosome stability, viral integration, and recombination. In this review, a survey of the binding affinity, specificity, and biological/pharmacological activities of some well-characterized G-quadruplex ligands is presented along with the potential importance of G-quadruplex DNA in vivo.

Our group is working on the development of reliable access to biologically relevant, long, and modified RNA sequences. Here, we briefly present the chemical synthesis of such sequences with 2?-O-triisopropylsilyloxymethyl (= 2?-O-tom) protected ribonucleoside phosphoramidites, their template-directed enzymatic ligation, and some examples of modified nucleotides, designed to promote structural and biological studies.

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Copyright of Revue Francophone des Laboratoires is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: Most of enterovirus infections are benign and the rate of mortality is low in countries with temperate climates. But since the late 1990s, Enterovirus 71 (EV-71) has become much more aggressive in Asian countries, with the outcome of a neurogenic pulmonary oedema syndrome and it is responsible for huge epidemics. The virological diagnosis rely upon viral isolation and identification by seroneutralisation, and upon the detection of specific IgM by ELISA and viral RNA by RT-PCR. There is no specific treatment to fight this virus, but innovative strategies, especially based on interfering RNA, are under investigation. [Copyright &y& Elsevier]

Abstract: Three new polyoma viruses have been recently identified; two of them, the KI et WU viruses are present in nasopharyngeal aspirates during the course of acute respiratory infections. The incidence of these viruses is low compared to other respiratory viruses and the disease has not shown a high severity of clinical signs. The physiopathology of the diseases and the mode of cultivation of these viruses remain unknown. The third virus was discovered from cutaneous biopsies of Merkel tumours with a higher incidence than in tissue from healthy patients. Its mode of transmission and its role in the cancerogenesis need more studies. However, as the virus can integrate into the cellular DNA, it signifies that the virus may have a role in various human tumors. [Copyright &y& Elsevier]

Abstract: The human bocavirus (HBoV) has been recently identified by means of molecular screening techniques in respiratory tract secretions from children with acute respiratory tract disease. This virus, which belongs to the Parvoviridae family, has been detected worldwide with a 5 to 10% prevalence among children with upper or lower respiratory tract infections, essentially during the winter period. A seroepidemiological study has shown that almost all the children have antibodies to HBoV by the age of five years, and HBoV infection seems to be rare in adults. HBoV is often detected in association with other respiratory viruses. This virus has also been detected in stools, but its role in gastroenteritis has not been yet established. Virological diagnostic of HBoV infection is based on the detection of viral DNA by PCR. Viral load determination by viral DNA quantitation in respiratory tract secretions could be a tool to differentiate between symptomatic HBoV infection and virus carriage. [Copyright &y& Elsevier]

Abstract: Coronaviruses are a large group of viruses and infect a lot of species of mammals and birds. Five coronaviruses currently infect humans: HCoVs 229E and OC43, identified in the 1960s, SARS-CoV identified in March 2003 during the SARS epidemic, and the HCoVs NL63 and HKU1, identified in 2004 and 2005 respectively. The genome of the coronaviruses is a linear, non-segmented, positive-sense single-stranded RNA molecule of approximately 30kb. The evolution of these viruses occurs through some features: the generation of multiple mutants during the replication resulting on a quasispecies structure of the viral population, the demonstrated ability of coronaviruses to establish persistent infections, the flexibility of the genome due to a high frequency of homologue or heterologue recombinations, the ability to jump barrier species and to adapt to the new environment. Two epidemiologic pictures of HCoV infections have to be distinguished: as suggested by recent studies, HCoVs except SARS-CoV, are distributed worldwide and cocirculate during seasonal outbreaks. The distribution of the different HCoV species varies according to the geographic area and season. In contrast, the SARS-CoV is responsible of the first emerging infectious disease of this millennium, infecting more than 8000 people between November 2002 and July 2003. Its circulation has been stopped by drastic public health policy. Human coronaviruses may be also involved in enteric and neurologic diseases. The detection of these viruses is difficult and mainly based on molecular assays (RT-PCR). There is no established specific therapy to date. [Copyright &y& Elsevier]

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Copyright of Revue Francophone des Laboratoires is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As the year 2003 was not only the 50th anniversary of the discovery of the DNA structure but also the 100th birthday of Rudolf Signer, the Department of Chemistry and Biochemistry at the University of Bern organized a Symposium on November 28th, in order to honour the pioneering work of its former faculty colleague Rudolf Signer. The invited symposium speakers covered a number of aspects related to the person and work of Rudolf Signer as well as ongoing research on the structure, function and use of DNA and nucleic acids.

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Abstract: Gaucher disease is one of the most prevalent lysosomal disorders. In this present study, we report a diagnostic strategy of type 1 Gaucher disease. The application of combined methods in molecular biology allowed us to analyse the p.Asn 370 Ser mutation. The affected individual activity is very low. First, we have to used the enzymatic digestion method. Then, we have to identified the mutation by the refractory mutation system technique using specific primers for the p.Asn 370 Ser mutation. These analyses are supplemented by the direct sequencing in order to seek and confirm this mutation. Finally, the absence of the 55 pb deletion in exon 9 among corroborated the presence of the homozygous genotype of this p.Asn 370 Ser in the patient DNA. [Copyright &y& Elsevier]

Abstract: Herpes simplex virus resistant to acyclovir (ACV) is a major concern among immunocompromised patients. ACV resistance might be due to mutations located in one of the two genes involved in ACV mechanism of action, the thymidine kinase gene (TK, involved in 95% of the cases) and the DNA polymerase gene. TK gene mutations consist, in half of the cases, in nucleotide insertion or deletion, occuring most of the time in G or C homopolymers considered as hot spots. Half of the other cases involves nucleotide substitutions leading to amino acids substitutions. Studies of sensitive strains revealed a high degree of TK polymorphism, many mutations being not implied in ACV resistance. At the present time, resistance detection can be performed by phenotypic tests that require virus culture and results cannot be given to the physician before 7 to 10 days. Genotyping diagnosis performed directly from clinical samples would allow to detect resistance more rapidly, in order to switch quickly to an appropriate treatment by foscarnet or cidofovir. [Copyright &y& Elsevier]

Alkylating agents belong to one of the oldest classes of anticancer drugs. Their therapeutic use dates back to the 1940’s with the drug mechlorethamine. The activity of these compounds varies based on monofunctional or bifunctional properties that create either simple adducts, such as triazine derivatives and methylating agents, or intra-and interstrand cross-links in nucleic acids. Many alkylating agents induce progressive tumour resistance through numerous mechanisms; some new agents can overcome this resistance. Numerous alkylating agents are prodrugs requiring bioactivation to produce their alkylating species, suggesting potential molecular changes that could improve their therapeutic ratios. They demonstrate a wide spectrum of activity, increasing interest in their use in combination with other cytotoxic and targeted treatments and, consistent with various hypotheses, in metronomic chemotherapy. [ABSTRACT FROM AUTHOR]

Abstract: Molecular fingerprinting methods are currently used to study microbial communities by culture independent approaches. They are proposed as identification tool owing to the availability of rapid automated methods. The 16S rRNA gene (16S rDNA) is an efficient marker for bacterial identification and microbial communities analysis. However, the 16S rDNA polymorphism among strains of the same species is an underestimated pitfall of the fingerprinting approaches. Aim of the study: We studied the 16S rDNA variability among strains of three bacterial species of medical interest. Material and methods: Total DNA was extracted from clinical isolates of Pseudomonas aeruginosa (N =20), Clostridium difficile (N =20) and Enterobacter cloacae (N =14). The Polymerase Chain Reaction (PCR) products obtained with consensus primers flanking the 16S rDNA variable regions V3 and V6-V7-V8 were separated by Temporal Temperature Gradient gel Electrophoresis (TTGE). DNA extracted from TTGE bands were sequenced and analysed. Results: All the isolates of P. aeruginosa and of C. difficile displayed one single TTGE band with constant migration distances suggesting that there was no 16S rDNA polymorphism among strains in these two species. Oppositely, the isolates of E. cloacae gave complex TTGE patterns formed by multiple bands with variable migration distances. These patterns corresponded to 16S rRNA genes variable in a single genome as well as among strains of the species. Conclusion: Intra-species and/or intragenomic variability of 16S rDNA should be taken into account for pertinent interpretation of molecular fingerprint. For this purpose, a comprehensive description of the polymorphism of this marker is necessary. [Copyright &y& Elsevier]

Abstract: The diagnosis of systemic Candidiasis is difficult to establish and biologic diagnosis raises problems. Blood culture which is the gold standard for the diagnosis of systemic Candidiasis lacks sensitivity and usually takes several days to become positive. Early diagnostic approach is imperative to avoid delays in the initiation for treatment. Therefore, nonculture methods like test for Candida antigen detection, metabolite detection or Candida DNA detection by PCR are being developed for the laboratory diagnosis. Candida derived metabolites and antigens detection lacks sensitivity. A new strategy consisting of the combined detection of mannanemia and an antibody response was developed. The combined detection has a high specificity and sensitivity in the diagnosis of invasive candidiasis. The results of tests for the detection of yeast DNA by PCR obtained recently are promising in terms of sensitivity, specificity and identification of species of Candida. [Copyright &y& Elsevier]

Abstract: In the past decades, blood donation screening contributed significantly to blood safety improvement, thanks to the increasing performances of serological and nucleic acid testing (NAT) assays, as well as the evolution of automated systems technology. The rapid pace of NAT development can be clearly seen to extend into the future. NAT for additional viruses as well as the use of new automated systems for individual donation or smaller mini-pool testing, with multiplex assays, is currently debated. However, few added benefit is expected for blood safety from such developments, while cost-effectiveness appears to be poor. The next step in laboratory automation will probably be the implementation of robotic pre- and post-analytical procedures. In this article we review the potential future evolutions of screening technologies in blood qualification platforms, particularly those derived from nanobiotechnologies. DNA microarrays, Lab-On-Chips, biosensors and nanoparticles (quantum dots) will probably play a major role in the coming decade. [Copyright &y& Elsevier]

Abstract: Nucleic acid testing is carried out in several steps: plasma pooling, nucleic acid extraction, amplification and detection. The target values of temperature, volume and incubation time are mentioned in the initial protocol without giving their limit values. The objective of this work was to determine the range of values in which the test remains positives. So we have tested: 1) the temperature and incubation time of plasma in lysis buffer (37 °C ± 3 et 30 min ± 10); 2) the influence of volume and incubation time of silica (50 μl ± 10 et 10 min ± 5); 3) the variation of the eluate volume after nucleic extraction. We have also studied the influence of the internal control volume variation. For each parameter the assays were performed at sensitivity limit of the technique and repeated several times. Our results showed that: 1) for all parameters evaluated the tests remain positive within a wide range of values; 2) It is not necessary to set up a sophisticated measurement process; 3) the technique is robust. [Copyright &y& Elsevier]

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Copyright of IBS, Immuno-analyse & Biologie Specialisee is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: Objective. – The aim of the study was to investigate two nosocomial outbreaks due to Salmonella Livingstone in a pediatric ward in Sfax hospital using molecular typing techniques. Materials and methods. – We included 84 strains of S. Livingstone isolated from patients hospitalized in a pediatric ward between November 1999 through August 2002 in addition to one environmental sample. Three epidemiological unrelated strains of S. Livingstone were also tested. The molecular typing techniques were: plasmid analysis, enterobacterial repetitive intergenic consensus (ERIC–PCR), random amplification of polymorphic DNA (RAPD–PCR) and pulsed field gel electrophoresis (PFGE). Results. – The plasmid analysis and the ERIC–PCR generated a similar profile for outbreak isolates including the environmental sample while the epidemiologically unrelated strains demonstrated distinct patterns. The RAPD–PCR applied on 20 strains showed three patterns but one profile was predominating. All the strains isolate of S. Livingstone, except the veterinary strain, could not be typed by PFGE. Conclusion. –> Using the molecular typing techniques, we showed that these two outbreaks in the pediatric ward were due to the clonal spread of a single strain of S. Livingstone. The identification of the source of contamination and the improvement of hygiene conditions are required. [Copyright &y& Elsevier]

Abstract: Background. – Many laboratories use the DNA Hybrid Capture® 2 HPV-high risk assay (Digene) to detect and type oncogenic HPV. The aim of this work was to compare this assay with a new HPV genotyping assay: HPV Consensus kit® (Argène). Actually, this assay is not commercialy available. Materials and methods. – Ninety-four cervical samples were tested with both the routine assay Hybrid Capture® 2 and the HPV Consensus kit®. Discordants results were analysed by amplification with a nested PCR and sequencing of amplified products. Results. – Only 81 results could be analysed concerning the oncogenic risk. The overall concordance was 92,6%. But we find 13 "generic" results with the HPV Consensus kit®, the generic probe including high risk and low risk genotypes. Conclusion. – HPV Consensus kit® results showed a better detection sensitivity for this assay than Hybrid Capture® 2 assay. Nevertheless, "generic" results give no information about the oncogenic risk of the HPV detected in a sample. [Copyright &y& Elsevier]

Abstract: We have used the sperm chromatin structure assay (SCSA) test in order to determine if correlations can be found between sperm DNA fragmentation and spermogram parameters. Only necrospermia and DNA fragmentation index are strongly correlated (P <0.0001). Neither fertilization rates for ICSI and IVF, nor blastocyst formation rates are impaired by a high DFI. However when the critical DFI>30% is reached, the chances of having ongoing pregnancies after blastocyst transfer are reduced by three. Treatments with antioxidants are of limited efficacy even though we obtained 2 deliveries after DFI treatments with such treatments. New strategies in order to improve the pregnancy rates for these peculiar cases of reduced fertility are discussed. [Copyright &y& Elsevier]

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The rate of mother-to-infant transmission for hepatitis C virus is estimated to be around 5% of viraemic mothers and represents an important route of HCV infection among children. Transmission is possible in utero but the highest risk of infection is at or near the time of delivery because of an important blood transmission of hepatitis C virus. Mothers with high levels of HCV-RNA and co-infected for human immunodeficiency virus are documented to have risk factors for vertical transmission of HCV. Thus, for these, the mode of delivery must be discussed even if there are no precise recommendations. Among obstetrical risk factors, the results of literature fail to prove a benefit of elective caesarean delivery in the aim to reduce the vertical transmission of HCV. However, obstetrical situations with a high risk of blood contact between mother and foetus must be considered and if possible evicted. [Copyright &y& Elsevier]

Nucleic Acid Testing (NAT) for HIV-1 and HCV has been introduced in France and became mandatory for all homologous blood donations since July 1st 2001 in addition to serology screening. Previously, a feasibility study led to the selection of 2 technologies : a TMA based assay (Chiron) uses the Procleix HIV-/HCV assay on pools of 8 samples and a PCR based assay from BioMe´rieux-Roche which is a combination of an RNA extraction system (NucliSens, BioMe´rieux) with a fully automated system for nucleic acid amplification and detection (Cobas Amplicor, Roche). This system uses the Cobas Ampliscreen HCV test v.2.0 and the The Cobas Ampliscreen HIV test v1.5, on 24 sample pools. Pooling was required because single-donation testing is not yet feasible, as a result of the limitations in automation available for all current NAT technologies. The two technologies were easily implemented and showed nearly the same detection limit for HCV RNA and HIV-1 RNA. During a one-year period, from July 1st 2001 to June 30, 2002, out of the 2.5 million donations tested, the NAT yield resulted in one HIV-1 RNA positive-antibody negative donation and one HCV RNA positive-antibody negative donation. Two HIV NAT positive-antibody negative donations were missed by minipool NAT because a very low viral load. Moreover, the NAT implementation did not impact on blood component availability, including platelet concentrates. [Copyright &y& Elsevier]

Methods for the regioselective introduction of alkoxymethyl-groups into the 2?-O-position of 5?-O-dimethoxytritylated, nucleobase-protected ribonucleosides and for the N-alkyloxycarbonylation of adenine and guanine nucleosides were developed. These methods were used for the preparation of RNA-phosphoramidites carrying novel fluoride- and photolabile sugar and nucleobase protecting groups.

The quantitation of nucleic acids and protein are measurements common to many applications in basic science and clinical research. Several different assays for either total protein or nucleic acids that can be performed in microplates are described. In addition, the fundamental differences between conventional tube-based instrumentation and microplate readers and how these differences relate to the assays are discussed.