Retention of Virus Versus Surrogate, by Ultrafiltration in Seawater: Case Study of Norovirus Versus Tulane

In the field of chemical engineering and water treatment, the study of viruses, included surrogates, is well documented. Often, surrogates are used to study viruses and their behavior because they can be produced in larger quantities in safer conditions and are easier to handle. In fact, surrogates allow studying microorganisms which are non-infectious to humans but share some properties similar to pathogenic viruses: structure, composition, morphology, and size. Human noroviruses, recognized as the leading cause of epidemics and sporadic cases of gastroenteritis across all age groups, may be mimicked by the Tulane virus. The objectives of this work were to study (i) the ultrafiltration of Tulane virus and norovirus to validate that Tulane virus can be used as a surrogate for norovirus in water treatment process and (ii) the retention of norovirus and the surrogate as a function of water quality to better understand the use of the latter pathogenic viruses. Ultrafiltration tests showed significant logarithmic reduction values (LRV) in viral RNA: around 2.5 for global LRV (i.e., based on the initial and permeate average concentrations) and between 2 and 6 for average LRV (i.e., retention rate considering the increase of viral concentration in the retentate), both for norovirus and the surrogate Tulane virus. Higher reduction rates (from 2 to 6 log genome copies) are obtained for higher initial concentrations (from 101 to 107 genome copies per mL) due to virus aggregation in membrane lumen. Tulane virus appears to be a good surrogate for norovirus retention by membrane processes.

An European overview of genetic counselling supervision provision

Genetic testing is becoming more commonplace in general and specialist health care, and should always be accompanied by genetic counselling, according to legislation in many European countries and recommendations by professional bodies. Personal and professional competence is necessary to provide safe and effective genetic counselling. Clinical and counselling supervision of genetics healthcare practitioners plays a key role in quality assurance, providing a safe environment not only for patients but for professionals too. However, in many European countries, genetic counsellors are still an emerging professional group and counselling supervision is not routinely offered and there are no enough evidences on the impact of these insufficiencies. This study aimed to explore the current status of genetic counselling supervision provision across Europe and to ascertain factors that might be relevant for the successful implementation of counselling supervision. A total of 100 practitioners responded to an online survey; respondents were from 18 countries, with the majority working in France (27%) and Spain (17%). Only 34 participants reported having access to genetic counselling supervision. Country of origin, the existence of a regulation system and years of experience were factors identified as relevant, influencing access and characteristics of counselling supervision. Although there is a growing number of genetic counsellors trained at European level, just a few countries have implemented and required as mandatory the access to genetic counselling supervision. Nevertheless, this is essential to ensure a safe and effective genetic counselling and should be regulated at the European genetic healthcare services.

Characterization of Functional Materials Using Coherence Scanning Interferometry and Environmental Chambers

Functional materials are challenging to characterize because of the presence of small structures and inhomogeneous materials. If interference microscopy was initially developed for use for the optical profilometry of homogeneous, static surfaces, it has since been considerably improved in its capacity to measure a greater variety of samples and parameters. This review presents our own contributions to extending the usefulness of interference microscopy. For example, 4D microscopy allows real-time topographic measurement of moving or changing surfaces. High-resolution tomography can be used to characterize transparent layers; local spectroscopy allows the measurement of local optical properties; and glass microspheres improve the lateral resolution of measurements. Environmental chambers have been particularly useful in three specific applications. The first one controls the pressure, temperature, and humidity for measuring the mechanical properties of ultrathin polymer films; the second controls automatically the deposition of microdroplets for measuring the drying properties of polymers; and the third one employs an immersion system for studying changes in colloidal layers immersed in water in the presence of pollutants. The results of each system and technique demonstrate that interference microscopy can be used for more fully characterizing the small structures and inhomogeneous materials typically found in functional materials.

The "extreme phenotype approach" applied to male breast cancer allows the identification of rare variants of ATR as potential breast cancer susceptibility alleles

In oncogenetics, some patients could be considered as "extreme phenotypes", such as those with very early onset presentation or multiple primary malignancies, unusually high numbers of cancers of the same spectrum or rare cancer types in the same parental branch. For these cases, a genetic predisposition is very likely, but classical candidate gene panel analyses often and frustratingly remains negative. In the framework of the EX2TRICAN project, exploring unresolved extreme cancer phenotypes, we applied exome sequencing on rare familial cases with male breast cancer, identifying a novel pathogenic variant of ATR (p.Leu1808*). ATR has already been suspected as being a predisposing gene to breast cancer in women. We next identified 3 additional ATR variants in a cohort of both male and female with early onset and familial breast cancers (c.7762-2A>C; c.2078+1G>A; c.1A>G). Further molecular and cellular investigations showed impacts on transcripts for variants affecting splicing sites and reduction of ATR expression and phosphorylation of the ATR substrate CHEK1. This work further demonstrates the interest of an extended genetic analysis such as exome sequencing to identify very rare variants that can play a role in cancer predisposition in extreme phenotype cancer cases unexplained by classical cancer gene panels testing.

The role of the Genetic Counsellor in the multidisciplinary team: the perception of geneticists in Europe

Genetics has begun to be considered a key medical discipline which can have an impact on everyday clinical practice. Therefore, it is necessary to understand what the most effective way is of caring for people affected by or at risk of genetic disorders. In this context, the team dealing with such patients has evolved with the emergence of the Genetic Counsellor figure. The profession of Genetic Counsellor appeared in Europe in 1980, but it is still a much-debated profession and not yet recognized in all European countries. The aim of this research is to investigate both how a team should be composed in the care of patients affected by or at risk of genetic disorders and what the role of the Genetic Counsellor should be-the field of action and the competences. The research has been carried out at the European level, submitting an online questionnaire to geneticists who, having the ultimate responsibility for the diagnosis and being in the field for the longest time, expressing their opinion, can identify strengths and potential areas for improvement in genetic care. 200 responses were collected from all over Europe. This led to awareness of the importance of the role of the counsellor within the medical genetics multidisciplinary team, and, above all, what the counsellor's skills and qualifications should be-for geneticists. Although this new profession has difficulties in being recognized in some countries, it seems clear that these highly competent professionals are essential for in-patient care and in the multidisciplinary team.

The Role of the European Society of Human Genetics in Delivering Genomic Education

The European Society of Human Genetics (ESHG) was founded in 1967 as a professional organisation for members working in genetics in clinical practice, research and education. The Society seeks the integration of scientific research and its implementation into clinical practice and the education of specialists and the public in all areas of medical and human genetics. The Society works to do this through many approaches, including educational sessions at the annual conference; training courses in general and specialist areas of genetics; an online resource of educational materials (EuroGEMS); and a mentorship scheme. The ESHG Education Committee is implementing new approaches to expand the reach of its educational activities and portfolio. With changes in technology, appreciation of the utility of genomics in healthcare and the public's and patients' increased awareness of the role of genomics, this review will summarise how the ESHG is adapting to deliver innovative educational activity.

Web-based return of BRCA2 research results: one-year genetic counselling experience in Iceland

There is an increased pressure to return results from research studies. In Iceland, deCODE Genetics has emphasised the importance of returning results to research participants, particularly the founder pathogenic BRCA2 variant; NM_000059.3:c.771_775del. To do so, they opened the website www.arfgerd.is . Individuals who received positive results via the website were offered genetic counselling (GC) at Landspitali in Reykjavik. At the end of May 2019, over 46.000 (19% of adults of Icelandic origin) had registered at the website and 352 (0.77%) received text message informing them about their positive results. Of those, 195 (55%) contacted the GC unit. Additionally, 129 relatives asked for GC and confirmatory testing, a total of 324 individuals. Various information such as gender and age, prior knowledge of the variant and perceived emotional impact, was collected. Of the BRCA2 positive individuals from the website, 74 (38%) had prior knowledge of the pathogenic variant (PV) in the family. The majority initially stated worries, anxiety or other negative emotion but later in the process many communicated gratitude for the knowledge gained. Males represented 41% of counsellees as opposed to less than 30% in the regular hereditary breast and ovarian (HBOC) clinic. It appears that counselling in clinical settings was more reassuring for worried counsellees. In this article, we describe one-year experience of the GC service to those who received positive results via the website. This experience offers a unique opportunity to study the public response of a successful method of the return of genetic results from research.

Invasive pulmonary aspergillosis in an ICU patient with Legionnaires' disease: A diagnostic challenge

Aspergillus fumigatus can cause a wide range of diseases, from hypersensitivity to invasive infection. Invasive disease usually occurs in severely immunocompromised patients with deep and prolonged neutropenia. It is a less well-recognized complication in critically ill patients without traditional risk factors. We describe a case of early invasive pulmonary aspergillosis (IPA) secondary to Legionella pneumophila serogroup 1 pneumonia in a patient on an intensive care unit (ICU). In addition to commonly accepted risk factors for IPA in ICU patients, we hypothesis that L. pneumophilia pneumonia could enhance this type of infection. We also reviewed all published cases of coinfection with L. pneumophila and A. fumigatus to assess whether Legionnaires' disease could be a risk factor for IPA.

The Global State of the Genetic Counseling Profession

The profession of genetic counseling (also called genetic counselling in many countries) began nearly 50 years ago in the United States, and has grown internationally in the past 30 years. While there have been many papers describing the profession of genetic counseling in individual countries or regions, data remains incomplete and has been published in diverse journals with limited access. As a result of the 2016 Transnational Alliance of Genetic Counseling (TAGC) conference in Barcelona, Spain, and the 2017 World Congress of Genetic Counselling in the UK, we endeavor to describe as fully as possible the global state of genetic counseling as a profession. We estimate that in 2018 there are nearly 7000 genetic counselors with the profession established or developing in no less than 28 countries.

Recontacting or not recontacting? A survey of current practices in clinical genetics centres in Europe

Advances in genomic medicine are improving diagnosis and treatment of some health conditions, and the question of whether former patients should be recontacted is therefore timely. The issue of recontacting is becoming more important with increased integration of genomics in 'mainstream' medicine. Empirical evidence is needed to advance the discussion over whether and how recontacting should be implemented. We administered a web-based survey to genetic services in European countries to collect information about existing infrastructures and practices relevant to recontacting patients. The majority of the centres stated they had recontacted patients to update them about new significant information; however, there were no standardised practices or systems in place. There was also a multiplicity of understandings of the term 'recontacting', which respondents conflated with routine follow-up programmes, or even with post-test counselling. Participants thought that recontacting systems should be implemented to provide the best service to the patients and families. Nevertheless, many barriers to implementation were mentioned. These included: lack of resources and infrastructure, concerns about potential negative psychological consequences of recontacting, unclear operational definitions of recontacting, policies that prevent healthcare professionals from recontacting, and difficulties in locating patients after their last contact. These barriers are also intensified by the highly variable development (and establishment) of the specialties of medical genetics and genetic counselling across different European countries. Future recommendations about recontacting need to consider these barriers. It is also important to reach an 'operational definition' that can be useful in different countries.

How practical experiences, educational routes and multidisciplinary teams influence genetic counselors' clinical practice in Europe

The main objective of our study was to explore whether, and to what extent, genetic counselors' characteristics impact on their tasks in practice. Specifically, we explored the complementariness between genetic counselors and medical geneticists and therefore looked at the most relevant tasks of genetic counselors, according to genetic counselors themselves and according to the medical geneticists they work with. A total of 104 genetic counselors and 29 medical geneticists from 15 countries completed a purposefully designed questionnaire. Results showed that most genetic counselors in Europe perform similar tasks, irrespective of their backgrounds. When looking at the factors influencing genetic counselors' roles data showed that the type of tasks performed by genetic counselors is associated with the years of experience in the field, not with their background or education. Of particular interest was the consensus between genetic counselors and medical geneticists regarding the genetic counselor's role. Not surprisingly, tasks with more psychosocial implications were seen as genetic counselors' eligibility while tasks with more medical implications were seen as medical geneticists' attribution. Our study shows that most genetic counselors work in tune with international recommendations and seem to be supportive of multidisciplinary teams. Corroborating our data with previous research, we discuss potential implications for practice and training in genetic counseling.

Complementarity between medical geneticists and genetic counsellors: its added value in genetic services in Europe

Clinical genetic services have progressed significantly the last few decades. This has led to the need for non-medical health-care professionals working as genetic counsellors in Europe and worldwide. However, there is no unified approach to genetic counsellors' role in health-care services in Europe, as in most countries the profession is still emerging and the educational backgrounds diverge noticeably, within and between countries. This qualitative study aims to describe the potential added value of genetic counsellors in clinical genetics teams and to explore their tasks and responsibilities in different European countries. A total of 143 participants providing genetic counselling in Europe at the time of the survey responded. The results show differences in activities of genetic counsellors, although there is a wide range of roles, which are similar. The ability to establish a quality relationship with consultands was frequently mentioned as one of the strengths of genetic counsellors, as well as a patient-centred approach. It is believed that genetic counsellors add a more holistic approach of psychosocial and familial dimensions of genetic concerns to the multidisciplinary teams. This study provides examples of successful integration of genetic counsellors in teams, as complementariness with medical geneticist became clear in several cases. Although the added value of genetic counsellors was manifested, professional recognition of genetic counsellors across Europe is still needed in order to support the quality of patients care and safety of practice.

[Severe pulmonary embolism revealed by status epilepticus]

INTRODUCTION

High-risk pulmonary embolism (PE) is associated with high mortality rate (>50%). In some cases, diagnosis of PE remains a challenge with atypical presentations like in this case report with a PE revealed by status epilepticus.

CASE REPORT

We report the case of a 40-year-old man without prior disease, hospitalized in ICU for status epilepticus. All paraclinical examinations at admission did not show any significant abnormalities (laboratory tests, cardiologic and neurological investigations). On day 1, he presented a sudden circulatory collapse and echocardiography showed right intra-auricular thrombus. He was treated by thrombolysis and arteriovenous extracorporeal membrane oxygenation. After stabilization, computed tomography showed severe bilateral PE. He developed multi-organ failure and died 4days after admission.

CONCLUSIONS

Pulmonary embolism revealed by status epilepticus has rarely been reported and is associated with poor prognosis. Physicians should be aware and think of the possibility of PE in patients with status epilepticus without any history or risk factors of seizure and normal neurological investigations.

Components of genetic counsellor education: A systematic review of the peer-reviewed literature

The need for appropriately trained genetic counsellors to support genetic healthcare is now acknowledged. However, while programmes for education of genetic counsellors exist in a number of countries, these do not conform to any specific international standards. As genetic techniques, educational standards and professional standards have been evolved, and with increasing mobility of genetic counsellors, it is of great importance to have some comparison of education and training between different countries. This systematic review was conducted to determine the components of educational programmes for genetic counsellors worldwide that have been published in peer-reviewed literature. Databases were searched for studies published in English from 2000 to 2014 related to the topic. We identified 406 potential papers, of these, 11 studies met the inclusion criteria. The findings indicate that, in most cases, the theoretical components of genetic counsellor programmes conform to the recommendations and requirements of relevant professional bodies. However, clinical preparation of genetic counsellors in real-life professional practice settings seems to be less well addressed as this is essential to ensure genetic counsellors are able to provide safe patient care after graduation. Further work to gain agreement internationally on genetic counsellor education is needed.

Prevalence and correlates of non-optimal secondary medical prevention in patients with stable coronary artery disease

BACKGROUND

In patients with coronary artery disease (CAD), non-optimal use of evidence-based medications is associated with an increased risk of adverse outcome.

AIMS

To assess the prevalence and correlates of non-optimal secondary medical prevention in patients with stable CAD.

METHODS

We included 4184 consecutive outpatients with stable CAD. Treatment at inclusion was classified as optimal/non-optimal regarding the four major classes of secondary prevention drugs: antithrombotics; statins; angiotensin-converting enzyme (ACE) inhibitors or angiotensin II receptor blockers (ARBs); and beta-blockers. For each treatment, the prescription was considered non-optimal if the drug was missing despite a class IA indication according to international guidelines. To assess the information globally, non-optimal secondary prevention was defined as at least one major treatment missing.

RESULTS

The proportions of patients with non-optimal treatment were 0.7%, 7.8%, 12.9% and 10.3% for antithrombotics, statins, ACE inhibitors/ARBs and beta-blockers, respectively. Non-optimal secondary medical prevention was observed in 16.8% of cases. By multivariable analysis, the correlates of non-optimal secondary medical prevention were long time interval since last coronary event (P<0.0001), older age (P<0.0001), diabetes mellitus (P<0.0001), hypertension (P<0.0001), no history of myocardial infarction (P=0.001), no history of coronary revascularization (P=0.013) and low glomerular filtration rate (P=0.042).

CONCLUSIONS

Although most patients with stable CAD are receiving evidence-based medications according to guidelines, there remain subgroups at higher risk of non-optimal treatment. In particular, it might be feasible to improve prevention by focusing on patients in whom a long time has elapsed since the last coronary event.

French professionals in genetic counselor careers

The profession of genetic counseling in France was recognized in 2004, based on the recommendations of a mandate commissioned by the Health Minister to explore the medical demographics of France. The report predicted a shortage of health professionals in the field of genetics, particularly in light of the rapid development of molecular testing. Development of the profession was supported by a legal framework, and today 107 genetic counselors have graduated from the specific educational program which awards the Professional Master's Degree of Human Pathology, entitled Master in Genetic Counseling and Predictive Medicine. Here we will trace the development of the profession in France and review the demographic characteristics of the students and genetic counselors practicing the profession today.

A study of the practice of individual genetic counsellors and genetic nurses in Europe

Advances in genetics have meant that the genetic services are now accessed by increasing numbers of patients. One way of dealing with the pressure on services without jeopardising patient care is the inclusion of nonmedical genetic counsellors and genetic nurses in the genetic services team. However, a cohesive approach to the profession has been lacking in Europe, and an educational programme and registration system for European practitioners is required. The aim of this study was to ascertain the type of work undertaken by genetic nurses and counsellors in Europe and the context in which they practised. We used a cross-sectional survey design to collect data from 213 practitioners, either genetic nurses or genetic counsellors, from 18 European countries. Respondents completed the survey online, and data were analysed using descriptive statistics and cross-tabulations. The majority were involved in undertaking the initial contact with the patient (89.9 %) and explaining the genetic test to the patient (91.5 %), while 74 % ordered tests and 91.4 % obtained informed consent for such tests. Psychological support before and after genetic testing was provided by 80.2 % of respondents, and 82.1 % reported regularly managing cases autonomously. While the genetic counselling profession is barely established in some countries, counsellors are able to contribute substantially to patient care as part of the multi-disciplinary team. Further efforts to establish the profession at the European level through a registration process will enhance the confidence in this new group of allied health professionals.

Transmission and characterization of bovine spongiform encephalopathy sources in two ovine transgenic mouse lines (TgOvPrP4 and TgOvPrP59)

Transgenic mice expressing the prion protein (PrP) of species affected by transmissible spongiform encephalopathies (TSEs) have recently been produced to facilitate experimental transmission of these diseases by comparison with wild-type mice. However, whilst wild-type mice have largely been described for the discrimination of different TSE strains, including differentiation of agents involved in bovine spongiform encephalopathy (BSE) and scrapie, this has been only poorly described in transgenic mice. Here, two ovine transgenic mouse lines (TgOvPrP4 and TgOvPrP59), expressing the ovine PrP (A136 R154 Q171) under control of the neuron-specific enolase promoter, were studied; they were challenged with brainstem or spinal cord from experimentally BSE-infected sheep (AA136 RR154 QQ171 and AA136 RR154 RR171 genotypes) or brainstem from cattle BSE and natural sheep scrapie. The disease was transmitted successfully from all of these sources, with a mean of approximately 300 days survival following challenge with material from two ARQ-homozygous BSE-infected sheep in TgOvPrP4 mice, whereas the survival period in mice challenged with material from the ARR-homozygous BSE-infected sheep was 423 days on average. It was shown that, in the two ovine transgenic mouse lines, the Western blot characteristics of protease-resistant PrP (PrPres) were similar, whatever the BSE source, with a low apparent molecular mass of the unglycosylated glycoform, a poor labelling by P4 monoclonal antibody and high proportions of the diglycosylated form. With all BSE sources, but not with scrapie, florid plaques were observed in the brains of mice from both transgenic lines. These data reinforce the potential of this recently developed experimental model for the discrimination of BSE from scrapie agents.

SERRS study of the DNA binding by Ru(II) tris-(Bipyridyl) complexes bearing one carboxylic group

Surface enhanced resonance Raman scattering (SERRS) is shown to be a satisfying method to study the interaction between DNA and ruthenium complexes [Ru(bpy)(2)(Hcmbpy)][PF(6)](2), where Hcmbpy = 4-carboxy-4'-methyl-2,2'-bipyridine. Such metallic complexes are known for their fluorescence properties. To validate this spectroscopic approach we have checked that i) at a given lambda(ex), silver colloidal SERRS spectra of Ru complexes closely resemble resonance Raman spectra in aqueous solutions, intensity excepted, and ii) the DNA fragments are not altered when they are adsorbed on the Ag nanoparticles surface. This investigation shows that the intensity of the Ru complexes SERRS spectra is reduced in the presence of DNA, in particular for the specific bands assigned to the Hcmbpy ligand. This collapse demonstrates that the Ru complexes bind DNA through the Hcmbpy moiety, and intercalation is suggested as the binding mode. The DNA binding by the enantiopure Ru complexes (Delta or Lambda) is more efficient than by the racemic complexes.

Fourier and wavelet transform analysis, a tool for visualizing regular patterns in DNA sequences

A correlation function that compares each base in a DNA sequence to its various neighbours and which is subsequently processed by Fourier and wavelet transforms has been developed. The procedure has been applied to sequences from the human chromosome 22, to nef genes from various HIV clones and to myosin heavy chain DNA. It permits to readily visualize regular features in DNA which are related to the stability of heteroduplexes formed upon strand slippage.

[Angioplasty or surgery in the patient with multivessel disease]

The aims of myocardial revascularisation are to treat angina, reduce ischaemia and improve life expectancy. Patients with multivessel disease have a poor prognosis, especially when the lesions are proximal, when the preseptal left anterior descending artery is involved and when left ventricular dysfunction is present. In this particular group of patients, coronary bypass surgery has been shown to improve 10 year survival. Coronary angioplasty has been compared with surgical treatment in many clinical trials. The medium-term survival is the same in both groups, but with a higher number of repeat procedures except in diabetic patients in whom mortality is higher after angioplasty. The use of coronary stents should reduce the number of post-angioplasty procedures. Constant technical improvements, the introduction of surgery without cardiopulmonary bypass, combined revascularisation procedures, new antiplatelet drugs, the absence of long-term comparative results, all this results in a personalized choice of revascularisation procedure based on the overall clinical and angiography features of each particular case.

Impact of C5-cytosine methylation on the solution structure of d(GAAAACGTTTTC)2. An NMR and molecular modelling investigation

The solution structures of d(GAAAACGTTTTC)2 and of its methylated derivative d(GAAAAMe5CGTTTTC)2 have been determined by NMR and molecular modelling in order to examine the impact of cytosine methylation on the central CpG conformation. Detailed 1H NMR and 31P NMR investigation of the two oligomers includes quantitative NOESY, 2D homonuclear Hartmann-Hahn spectroscopy, double-quantum-filtered COSY and heteronuclear 1H-31P correlation. Back-calculations of NOESY spectra and simulations of double-quantum-filtered COSY patterns were performed to gain accurate information on interproton distances and sugar phase angles. Molecular models under experimental constraints were generated by energy minimization by means of the molecular mechanics program JUMNA. The MORASS software was used to iteratively refine the structures obtained. After methylation, the oligomer still has a B-DNA conformation. However, there are differences in the structural parameters and the thermal stability as compared to the unmethylated molecule. Careful structural analysis shows that after methylation CpG departs from the usual conformation observed in other ACGT tetramers with different surroundings. Subtle displacements of bases, sugars and backbone imposed by the steric interaction of the two methyl groups inside the major groove are accompanied by severe pinching of the minor groove at the C-G residues.

Conformational variation of the central CG site in d(ATGACGTCAT)2 and d(GAAAACGTTTTC)2. An NMR, molecular modelling and 3D-homology investigation

The determination of the solution structure of two self-complementary oligomers d(ATGACGTCAT)2 (CG10) and d(GAAAACGTTTTC)2 (CG12), both containing the 5'-pur-ACGT-pyr-3' sequence, is reported. The impact of the base context on the conformation of the central CpG site has been examined by a combined approach of: (a) 2D 1H-NMR and 31P-NMR; (b) molecular mechanics under experimental constraints; (c) back-calculations of NOESY spectra and iterative refinements of distances; and (d) 3D-homology search of the central tetrad ACGT within the complete oligonucleotides. A full NMR study of each fragment is achieved by means of standard 2D experiments: NOESY, 2D homonuclear Hartmann-Hahn spectroscopy, double-quantum-filtered COSY and heteronuclear 1H-31P correlation. Sugar phase angle, epsilon-zeta difference angle and NOE-derived distances are input as experimental constraints to generate molecular models by energy minimization with the help of jumna. The morass program is used to iteratively refine the structures obtained. The similarity of the two ACGTs within the whole oligonucleotides is investigated. Both the decamer and the dodecamer adopt a B-like DNA conformation. However, the helical parameters within this conformational type are significantly different in CG12 and CG10. The central CpG step conformation is not locked by its nearest environment (5'A and 3'T) as seen from the structural analysis of ACGT in the two molecules. In CG12, despite the presence of runs of A-T pairs, CpG presents a high twist of 43 degrees and a sugar phase at the guanine of about 180 degrees, previously observed in other ACGT-containing-oligomers. Conversely, ACGT in CG10 exhibits strong inclinations, positive rolls, a flat profile of sugar phase, twist and glycosidic angles, as a result of the nucleotide sequence extending beyond the tetrad. The structural specificity of CG10 and its flexibility (as reflected by its energy) are tentatively related to the process of recognition of the cyclic AMP response element by its cognate protein.