[Involuntary Psychiatric Hospitalizations: From request to a call center to hospitalization]. / Admission en soins psychiatriques a la demande d'un tiers : de l'appel au SAMU a l'hospitalisation.

BACKGROUND: Involuntary psychiatric hospitalization (IPH) is a heavy and complex psychiatric exception measure. In the Seine-Saint-Denis department (low medical density), the evaluation of the patient in psychiatric decompensation is the responsibility of the out-of-hours general practitioners (GP) mandated by the call center. Their feeling is the non-achievement of the procedure once the patient arrives at the emergency room. We aimed to evaluate the outcome of patients following a request for IPH from these GP. METHODS: We conducted a retrospective study based on all requests for IPH received during 2016 at the Seine-Saint-Denis emergency medical call center. The characteristics of the call and the patient, as well as the decisions of the regulator and the GP were collected. The decision of hospitalization in the emergency room was sought for patients referred for IPH. RESULTS: Of the 7541 calls for decompensation, 539 were for an IPH. These calls occurred during non-working hours in 55 % of cases. A GP was involved in more than two-thirds of the cases and requested an IPH for 240/304 (79 %) patients. Patients were male in 56 % of cases with an average age of 40 (±16) years. IPH was confirmed for 132 (61 %) patients. This rate did not differ from the 65 % reported in the literature (Z-test, P=0.26). Voluntary hospitalization was performed for 37 (17 %) other patients. DISCUSSION: The IPH rate for patients referred by GP mandated by the call center was comparable to that following the requests of the attending physicians, validating their intervention in this critical context.

[COP21 - Organization and activity of a medical cover under "pressure"]. / COP21 ­ Organisation et bilan d'une médicalisation sous haute tension.

INTRODUCTION: The United Nations Climate Conference (COP21) gathered in France for delegations from all around the world, with 20,000 delegates from 195 countries every day, including 150 heads of states during the first 48hours. A specific medical cover was organized in a particular "post-attacks" context and with harsh constraints due to delimitation of an inner zone under the sole UN authority ("blue zone"). OBJECTIVE: To evaluate medical means involved and medical activity. METHODS: Medical cover was managed by SAMU 93 in collaboration with zonal SAMU and regional health agency for the entire site including the "blue zone". End-points: engaged workforce, number of visits, including transfers and medicalized transfers. RESULTS: In "France zone" (operational headquarters): an emergency physician dispatcher and an assistant for 20 days. In "blue zone": 20 rescuers, mobile intensive care unit H24 and two emergency physicians (consultations) 12/24hours for 16 days. A total of 47 doctors, 25 nurses, 25 paramedics and 20 assistants participated in the medical service. This corresponded to three emergency physician full medical time equivalents (FMTE) for 16 days. Consultations performed: 1238 or 97/day resulting in 34 (3%) transfers including seven medicalized. Patients were 706 (57%) men and 495 (43%) women, with mean age of 43±1 years. Trauma patients were most numerous (20%). CONCLUSION: Medical means involved were consistent for 16 days. The medical activity was sustained, but medicalized transfer rarely required.

Quantifying physician's bias to terminate resuscitation. The TERMINATOR study.

CONTEXT: Deciding on "termination of resuscitation" (TOR) is a dilemma for any physician facing cardiac arrest. Due to the lack of evidence-based criteria and scarcity of the existing guidelines, crucial arbitration to interrupt resuscitation remains at the practitioner's discretion. AIM: Evaluate with a quantitative method the existence of a physician internal bias to terminate resuscitation. METHOD: We extracted data concerning OHCAs managed between January 2013 and September 2021 from the RéAC registry. We conducted a statistical analysis using generalized linear mixed models to model the binary TOR decision. Utstein data were used as fixed effect terms and a random effect term to model physicians personal bias towards TOR. RESULTS: 5,144 OHCAs involving 173 physicians were included. The cohort's average age was 69 (SD 18) and was composed of 62% of women. Median no-flow and low-flow times were respectively 6 (IQR [0,12]) and 18 (IQR [10,26]) minutes. Our analysis showed a significant (p < 0.001) physician effect on TOR decision. Odds ratio for the "doctor effect" was 2.48 [2.13-2.94] for a doctor one SD above the mean, lower than that of dependency for activities of daily living (41.18 [24.69-65.50]), an age of more than 85 years (38.60 [28.67-51.08]), but higher than that of oncologic, cardiovascular, respiratory disease or no-flow duration between 10 to 20 minutes (1.60 [1.26-2.00]). CONCLUSIONS: We demonstrate the existence of individual physician biases in their decision about TOR. The impact of this bias is greater than that of a no-flow duration lasting ten to twenty minutes. Our results plead in favor developing tools and guidelines to guide physicians in their decision.

Morphology and morphometry of Paratanaisia bragai () Freitas, 1959 (Digenea, Eucotylidae) through light and scanning electron microscopy.

Paratanaisia bragai is a digenetic trematode that reaches sexual maturity in the kidney collecting ducts of domestic and wild birds, while the snails Subulina octona and Leptinaria unilamellata serve as its intermediate hosts in Brazil. The present study analyzed the morphology and morphometry of P. bragai. Adult specimens of the parasite were collected from naturally infected Columba livia kidneys, fixed and prepared for observation via bright field and differential interference contrast light microscopy and scanning electron microscopy. The parasite has an elongated and flattened body, with a subterminal oral sucker located at the anterior end of the body, as observed by all techniques used. Staining the parasite with hematoxylin-eosin enabled observation of the pharynx, located posteriorly to the oral sucker, the vitelline glands, which are extra-cecal and extend anteriorly to the pre-ovarian region and later to the median region of the body, and intestinal caeca parallel to the vitelline glands. The presence and functionality of the acetabulum are controversial points in the literature, but it was observed in all specimens analyzed by scanning electron microscopy, with a major diameter of 38.36 ± 6.96 (28.77 - 45.39) and minor diameter of 31.59 ± 7.04 (21.75 - 38.16). Close to the acetabulum, scales were observed in the integument of the parasite. Scales with (1 - 5) blade divisions were identified. In the genital pore, it was possible to see the everted cirrus with rosette shape. The excretory pore (first morphometric record) is dorsal and subterminal, with major diameter of 12.27 ± 9.16 (5.79 - 18.75) and minor diameter of 3.95 ± 1.49 (2.89 - 5.00).

Further description of Cruzia tentaculata (Rudolphi, 1819) Travassos, 1917 (Nematoda: Cruzidae) by light and scanning electron microscopy.

Species of Cruzia are parasites of the large intestine of marsupials, reptiles, amphibians, and mammalians. Cruzia tentaculata specimens were collected from the large intestine of Didelphis marsupialis (Mammalia: Didelphidae) from Colombia (new geographical record) and from Brazil and analyzed by light and scanning electron microscopy. The morphology of males and females by light microscopy corroborated most of the previous description and the ultrastructure by scanning electron microscopy evidence: the topography of the cuticle, deirids, amphids, phasmids in both sexes, a pair of papillae near the vulva opening, and the number and location of male caudal papillae, adding new features for species identification only observed by this technique.

Does endotracheal intubation increases chest compression fraction in out of hospital cardiac arrest: A substudy of the CAAM trial.

BACKGROUND: Optimal out of hospital cardiac arrest (OHCA) airway management strategies remain unclear. We compared chest compression fraction (CCF) between patients receiving endotracheal intubation (ETI) versus bag mask ventilation (BMV). METHODS: We studied adult OHCA enrolled from our center in the CAAM trial. Primary exposures were ETI or BMV. Primary outcome was whole intervention CCF, adjusted for Utstein confounders. Secondary outcomes were per cycle CCF, no flow time associated (NFT) with ventilation, rhythms checks and mechanical chest compression device placement. RESULTS: Of 2040 OHCA enrolled in the CAAM trial we analyzed 112 cases recruited by our center. Unadjusted CCF was 0.89 for ETI and 0.88 for BMV (p = 0.19). Compared with BMV, ETI achieved lower NFT associated with ventilations (32 vs 127 s; p < 0.001). ETI cases experienced higher NFT associated with rhythm checks (69.5 vs 42.5 s p = 0.02) and with mechanical chest compression placement (29 vs 20 s; p = 0.04). CCF was higher during the first cycle in BMV than in ETI patients (0.81 vs 0.74; p = 0.02). After correction for confounders we observed no difference in global intervention CCF between the ETI and BMV (ΔCCF [ETI-BMV] 0.301; [95%CI: -1.9 to 2.51]; p = 0.79). CONCLUSION: In our substudy whole intervention CCF among OHCA was not modified by ETI compared to BMV. In the ETI group we observed lower NFT associated with ventilations and higher NFT associated with mechanical chest compression devices placement. CCF was lower in the ETI group during the first cycle.

[When the patient calls the SAMU because his pacemaker is making "beep-beep". Study on physicians' knowledge on pacemaker sound alarm]. / Quand le patient appelle le Samu car son pacemaker fait « tic-tac ¼. Enquête sur la connaissance de l'existence d'une alarme sonore dans les pacemakers.

INTRODUCTION: More than 60,000 pacemakers are inserted every year in France. This number has been steadily increasing for a decade. Miscellaneous incidents can lead patients with pacemakers or their relatives to contact emergency services. Following the call to the SAMU-Center 15 of a asymptomatic 90-year-old woman reported that her pacemaker was making "beep-beep", we assessed the knowledge of physicians of the SAMU-Center 15 (call center) dispatching center on the existence of pacemaker sound alarms. METHODS: Forty-two physicians, emergency physicians and general practitioners, regularly participating in the medical dispatching of the SAMU-Center 15 in Seine-Seine-Denis were interviewed. We asked them how a patient with a pacemaker could be informed of a malfunction of it without being symptomatic. RESULTS: No physician interviewed mentioned an audible alarm. All of them confirmed their ignorance of its existence. One physician had already been asked for a similar reason and had referred the patient to the emergency department without knowing it was an alarm. CONCLUSION: Patients and physicians seem insufficiently aware of the existence of the existence of pacemakers' sound alarm. An effort must be made regarding the information on the existence of such an alarm and the way to managed it.

Difficult intubation in thyroid surgery: myth or reality?

Thyroid surgery is considered to be a risk factor for difficult airway management. We prospectively studied 324 consecutive patients undergoing thyroid surgery to investigate the incidence of difficult intubation as evaluated by the intubation difficulty scale as well as other specific predictive factors. The overall incidence of difficult intubation was 11.1% (95% CI: 7.6-14.5). Median intubation difficulty scale was 0 (25th-75th percentile: 0; 2.7). In three predefined groups (no echographic goiter, clinically palpable goiter, and impalpable goiter), difficult intubation occurred in 10% (95% CI: 4.8-17.4), 13% (95% CI: 6.5-18.4), and 11% (95% CI: 4.7-16.8) of patients, respectively, with no statistical difference among the groups. Specific predictive criteria (palpable goiter, endothoracic goiter, airway deformation, airway compression, or thyroid malignancy) were not associated with an increased rate of difficult intubation. Classical predictive criteria (mouth opening <35 mm, Mallampati III or IV, short neck, neck mobility <80 degrees , thyromental distance <65 mm, and a retrognathic mandible) were significantly reliable in the univariate analysis as risk factors for difficult intubation.

[Evaluation of patients' knowledge regarding counsels provided in case of chest pain after an acute myocardial infarction]. / Evaluation des conseils assimilés par les patients sur l'attitude recommandée en cas de douleur thoracique au décours d'un infarctus aigu du myocarde. Conseils ou patient après un infarctus du myocarde.

INTRODUCTION: an early call to the department of urgent medical assistance--Center 15 (SAMU-centre 15) is associated to shortest delays of reperfusion in case of myocardial infarction. However, patients are not always aware of this. OBJECTIVE: to assess the assimilated counsels by patients after an acute myocardial infarction. METHODS: from January 1998 to June 2004, patients managed by SAMU 93 and having benefited from thrombolytic therapy prior to hospitalization and/or primary angioplasty for a ST+ acute coronary syndrome with a confirmation of acute myocardial infarction during their hospital stay were prospectively enrolled into this study. A questionnaire was administered by phone from december 2003 to july 2005, assessing the knowledge about the necessity to alert SAMU-center 15 in case of chest pain and availability of medical files data. RESULTS: among the 976 patients: 111 (11%) were lost during follow-up, 162 (19%) were deceased when phone contact and 119 (12%) could not be interrogated. Among the 584 (60%) remaining subjects interrogated with a median follow-up period of 985 days (413-1596), 290 (50%) patients answered they received counseling, including 156 (27%) for taking nitrates, 19 (29%) stated they know that they should call SAMU-center 15. Patients with a high level of education and those treated by thrombolytic therapy prior to hospitalization were better informed; 464 (79%) patients declared having a prescription, 392 (67%) a hospital report, 406 (69%) an electrocardiogram, 227 (39%) a CD with their coronary angiography, and 79(14%) their medical file. CONCLUSION: the level of knowledge regarding the recommended attitude in case of chest pain is poor. The availability of medical data was better. Arch Mal Cceur

Measurement of carbon monoxide in simulated expired breath.

BACKGROUND: Environmental carbon dioxide (CO) detectors used as an early warning method have been adapted to measure CO concentration in expired breath. This technique has been validated in smokers with relatively low CO concentrations, but its applicability to poisoning has not been demonstrated. OBJECTIVE: To compare the reliability of toxicologically significant CO measurements performed using a portable CO detector with those obtained using infrared spectrometry, the standard method for blood CO concentration determination. DESIGN: Experimental study with a CO detector and infrared spectrometer. A balloon simulated respiratory movements and an expired breath. Balloon gas mixtures contained CO, in one of 21 different concentrations from 100 to 600 parts per million (ppm) in air. CO concentration was measured directly with the portable CO detector and two gas samples obtained at the beginning and end of the simulated expired breath were diluted, with validation, for spectrometric measures. MAIN OUTCOME MEASURES: Portable CO detector concentrations were compared with the mean value of the reference method. Simple linear regression was performed using ANOVA to evaluate the parallel between the model with the reference method. RESULTS: Portable CO detector concentration measurements were perfectly linear (R2=0.989, P<10(-3)) over a concentration range of 46-645 ppm. The difference from the reference plot was significant (P<0.01). CONCLUSION: Given the linearity of the measurements, the underestimation by the portable CO detector at higher concentrations can be corrected mathematically. A portable CO detector should measure CO in expired breath efficiently and reliably.

[Intraspinal air, a rare complication of blunt chest trauma]. / Le pneumorachis, complication rare du traumatisme thoracique fermé.

Pneumorachis, defined as the presence of air within the spinal canal, has rarely been described, and is exceptionally due to thoracic trauma. We report the case of a 37-year-old patient who sustained a motor vehicle accident. The chest CT-scan showed a bilateral-hemothorax, a small right pneumothorax, rib fractures, and a fracture of the fourth thoracic vertebra associated with air in the spinal canal extending from T6 to L2. The fracture of T4 associated with the pleural lesion is probably responsible for the pneumorachis. Possible pathogenic mechanisms of this rare blunt chest complication are discussed.

[Interest of prehospital use of cardiac output monitoring with partial CO2 rebreathing technique: a case report]. / Intérêt du monitorage du débit cardiaque en situation préhospitalière par la technique de la réinhalation partielle du CO2: à propos d'une observation.

We report the case of a 68-year-old man with severe hypoxemic pneumopathy having cardiac output monitoring with the NICO system in prehospital medicine. This monitoring permitted the diagnosis of a compressive pneumothorax during the transfer to the intensive care unit. This ease of use technique based on partial carbon dioxide rebreathing, allows non-invasive, continuous and reliable cardiac output monitoring. We discuss the interest of this device in prehospital medicine.

[Emergency ambulance management of acute pain in children: a national survey]. / Douleur aiguë de l'enfant dans l'aide médicale d'urgence. Evaluation des pratiques.

OBJECTIVES: To assess the knowledge and skills of physicians staffing mobile intensive care units (emergency ambulances) in the management of severe acute pain in children. METHODS: Questionnaire-based telephone interviews with emergency physicians of all urban emergency ambulance services (n=360). This questionnaire covered knowledge of procedures for assessment of pain, definition of severe acute pain and its, treatment, availability of morphine and similar drugs, local guidelines and the physicians' opinion of the national guidelines. RESULTS: Physicians from all but one ambulance service responded. Forty-nine percent were unaware of the French Society of Anesthesiology and Intensive Care guidelines, and 63% had no local guidelines. Eight percent defined severe acute pain correctly and 10% defined the therapeutic objective correctly. Forty-seven percent used morphine (which was available for 93%), and 7% and 13% respectively followed guidelines about doses and waiting periods between administrations. CONCLUSION: This survey showed inadequate knowledge about the management (assessment and treatment) of severe acute pain in children in prehospital emergency settings. Training in this area is essential.

[Peripheral venous placement: evaluation of guidelines respect in prehospital setting]. / Evaluation du respect des recommandations pour la mise en place des voies veineuses périphériques en médecine d'urgence préhospitalière.

INTRODUCTION: Respect of guidelines for peripheral venous placement has never been studied in prehospital setting. OBJECTIVE: Describe prehospital practice in peripheral venous placement and perform comparison with guidelines. MATERIAL AND METHODS: Prospective study, in mobile intensive care unit from a university hospital, October 2002 to January 2003. Study of prehospital practice for peripheral venous placement in prehospital setting and comparison with guidelines. Guideline from Anaes: wearing a cap and a mask, washing hands, washing insertion site with water and soap, wearing sterile gloves, using sterile gauze, applying iodine solution to the insertion site, using catheter with a protective system and applying occlusive dressing. RESULTS: Six hundred seventy-three reports were studied. A cap and a mask wearing and washing insertion site with water and soap were never respected. Washing hand with antiseptic was reported in 56% of the cases, washing insertion site with iodine solution in 4%, wearing sterile gloves in 21%, using catheter with a protective system in 89%, using sterile gauze in 1% and applying occlusive dressing in 99%. For each criterion, respect of guidelines was significantly more frequent in nurse practice than in physician practice. CONCLUSION: Guidelines for peripheral venous placement were not respected in prehospital setting. Education and formation are necessary to optimize infectious risk prevention in prehospital care.

Value of C-reactive protein in the detection of bacterial contamination at the time of presentation in drug-induced aspiration pneumonia.

STUDY OBJECTIVES: To compare the plasma concentration of C-reactive protein (CRP) with traditional markers for diagnosis of bacterial pneumonia in patients with suspected aspiration. DESIGN: Prospective, nonrandomized, controlled study of consecutive hospital admissions. SETTING: Toxicology ICU in a university hospital. PATIENTS OR PARTICIPANTS: Acutely poisoned comatose patients admitted to the hospital with suspicion of aspiration pneumonia. INTERVENTIONS: Distal protected catheter sampling per fiberoptic bronchoscopy and bacteriologic culture were employed as a standard to detect the bacterial component of suspected aspiration pneumonia. Plasma CRP concentrations, temperature, and WBC count were measured on hospital day 1. MEASUREMENTS AND RESULTS: Sixty-six patients were evaluated. Thirty-two had bacterial contamination by positive culture (> or =10(3) cfu/mL). Multiple receiver-operating characteristic (ROC) curves were used to compare each parameter for detection of infection secondary to aspiration. The ROC curve of CRP concentrations showed that a CRP >75 mg/L is associated with bacterial contamination with a sensitivity of 87%, specificity of 76%, positive predictive value of 78%, and negative predictive value of 87%. ROC curves of temperature and WBC count demonstrated poor diagnostic value of these markers in indicating the bacterial component of suspected aspiration pneumonia. CONCLUSIONS: Early measurement of CRP is useful for the diagnosis of aerobic bacterial content of aspiration pneumonia and perhaps in determining the need for invasive bacteriologic sampling. Temperature and WBC count are poor indicators of bacterial infection of aspiration pneumonia in poisoned patients.

Prolonged severe hypercapnia complicating near fatal asthma in a 35-year-old woman.

OBJECTIVE: We describe a patient with a prolonged and severe hypercapnia occurring during an episode of status asthmaticus induced by ophthalmic instillation of carteolol. SETTING: Prehospital Emergency Medical Service and Pulmonary Intensive Care Unit in a university hospital. PATIENT: A 35-year-old female developed an acute asthma attack while at home, which required advanced life support. INTERVENTION: On hospital admission, arterial blood gases revealed a PaCO2 of 208 mmHg. Hypercapnia persisted with a PaCO2 of more than 190 mmHg for 10 h, with pH always less than 7.00. The patient was finally discharged after 26 days without sequelae. CONCLUSION: This case illustrates the cerebral and cardiovascular tolerance of severe and prolonged hypercapnia associated with major acidosis.

Complication profiles of adult asthmatics requiring paralysis during mechanical ventilation.

OBJECTIVE: To assess the characteristics and the incidence of morbidity of intubated asthmatic patients who received long-term paralysis. DESIGN: Retrospective cohort study. SETTING: Five intensive care units (ICUs) in Paris and the surrounding suburbs. PATIENTS AND PARTICIPANTS: The NMB group consisted of patients who received neuromuscular blocking agents for more than 12 h (NMB group) versus sedation alone (SED). INTERVENTIONS: None. MEASUREMENTS AND RESULTS: The incidence of post-extubation muscle weakness and/or myopathy was 18% in the NMB group compared to 2% in the SED group ( p=0.01). The occurrence of ventilator-associated pneumonia was higher in the NMB group (42% versus 4%; p<0.0001). The duration of ICU stay and of mechanical ventilation were significantly greater in the NMB group. Multiple logistic regression analysis showed that inclusion in the NMB group was the only independent predictor of the presence of the overall morbidity [odds ratio 6.4 (2.09; 19.64)]. CONCLUSION: While greater initial severity of respiratory compromise in the NMB group may explain part of the difference, use of NMB agents appears to be strongly related to the presence of significant complications among mechanically-ventilated asthmatic patients.

Trends in opiate and opioid poisonings in addicts in north-east Paris and suburbs, 1995-99.

AIMS: (1). To assess the trends in the number, mortality and the nature of severe opiate/opioid poisonings from 1995 to 1999 in north-east Paris and adjacent suburbs and (2). to examine the effects of the introduction of high-dose buprenorphine on these parameters. DESIGN: Retrospective, 5-year study with review of pre-hospital, hospital and post-mortem data. SETTING AND PARTICIPANTS: Eighty patients from the toxicological intensive care unit (TICU) in north-east Paris, 421 patients from the pre-hospital emergency medical service in a north-east suburb of Paris (SAMU 93) and 40 deaths from the coroner's office in Paris. MEASUREMENTS AND RESULTS: We found that the number of pre-hospital opiate/opioid poisonings and deaths decreased over 5 years. During the same time frame, opiate/opioid poisoning admissions to our TICU remained steady, but the number of deaths declined. From 1995 to 1999, the detection of buprenorphine among opiate/opioid-poisoned TICU patients increased from two to eight occurrences per year while detection of opiates diminished from 17 to 10 occurrences per year. Increased buprenorphine detection correlated directly with increasing sales over this time period. In spite of the increased use of buprenorphine, the mortality associated with opiate/opioid poisonings has diminished in the pre-hospital environment from 9% in 1995 to 0% in 1999, and in the TICU from 12% in 1995 to 0% in 1997 and thereafter. We found a high frequency of multiple opiate/opioid use in severe poisonings, as well as the frequent association of other psychoactive drugs including ethanol. CONCLUSIONS: The number and the mortality of opiate/opioid poisonings appear to be stable or decreasing in our region. The association of multiple opiates/ opioids appears nearly as common as the association with other psychoactive drugs. The introduction of high-dose buprenorphine coincides with a decrease in opiate/opioid poisoning mortality. Further study will be necessary to clarify this observation.

FTIR study of specific binding interactions between DNA minor groove binding ligands and polynucleotides.

The use of FTIR spectroscopy is made to study the interactions between polynucleotides and two series of minor groove binding compounds. The latter were developed and described previously as part of an ongoing program of rational design of modified ligands based on naturally occurring pyrrole amidine antibiotic netropsin, and varying the structure of bisbenzimidazole chromosomal stain Hoechst 33258. Characteristic IR absorptions due to the vibrations of thymidine and cytosine keto groups in polynucleotides containing AT and GC base pairs respectively are used to monitor their interaction with the added ligands. Although the two thiazole based lexitropsins based on netropsin structure differ in the relative orientation of nitrogen and sulfur atoms with respect to the concave edge of the molecules, they interact exclusively with the thymidine C2 = O carbonyl groups in the minor groove of the alternating AT polymer as evidenced by specific changes in the IR spectra. In the second series of compounds based on Hoechst 33258, the structure obtained by replacing the two benzimidazoles in the parent compound by a combination of pyridoimidazole and benzoxazole, exhibits changes in the carbonyl frequency region of poly dG.poly dC which is attributed to the ligand interaction at the minor groove of GC base pairs. In contrast, Hoechst 33258 itself interacts only with poly dA.poly dT. Weak or no interaction exists between the ligands and any of the polynucleotides at the levels of the phosphate groups or the deoxyribose units.