Prevalence and factors associated with methicillin-resistant Staphylococcus aureus colonization on admission to geriatric care units: impact on screening practices

OBJECTIVES

Universal screening for methicillin-resistant Staphylococcus aureus (MRSA) entails additional costs, and there is no consensus for targeted screening for high-risk units. The aims of this study were to determine the prevalence of MRSA in geriatric care units, and to identify the factors associated with MRSA colonization on admission.

METHODS

This retrospective case-control study (1:1) in the geriatric care unit of six Belgian hospitals covered the period from 1st January 2021 to 31st December 2022. Cases were patients with a positive MRSA screening result within 48 h of admission to the geriatric care unit, and controls were patients with a negative screening result.

RESULTS

In total, 556 patients were included in this study (278 in each group). Prevalence per 100 admissions for the total sample was 2.3 [95% confidence interval (CI) 2.2-2.6]. Significant multi-variate factors associated with MRSA carriage on admission were: history of MRSA, nursing home origin, and chronic skin lesions. Applying these three factors would give an area under the receiver operating characteristic (ROC) curve of 0.73 (95% CI 0.71-0.77), and would allow screening to be carried out in only 55.4% of cases (95% CI 51.2-59.6%).

CONCLUSIONS

Using these factors as screening criteria in geriatric care units could significantly reduce the number of patients screened for MRSA, while maintaining satisfactory sensitivity and specificity.

Seizure recurrences in generalized convulsive status epilepticus under sedation: What are its predictors and its impact on outcome?

BACKGROUND

Management of status epilepticus (SE) is focused on the early seizure termination. Refractory SE is an indication for sedation in patients with SE, but up to 75% of patients may be ventilated due to a neurological or respiratory failure. In patients requiring sedation, the clinical assessment is not sufficient to assess seizure control. Identifying those at risk of recurrent seizures could be useful to adapt their management. On the other hand, patients with low risk could benefit from an early withdrawal of sedation to avoid the impact of inappropriate sedation on outcome.

OBJECTIVE

To determine the prevalence and the predictors of uncontrolled SE and its impact on outcome in patients with generalized convulsive SE (GCSE) requiring mechanical ventilation (MV).

METHODS

We retrospectively included patients admitted to the intensive care unit with GCSE requiring MV. Uncontrolled SE was defined as persistent or recurrent seizures during sedation or within 24hours following withdrawal. A multivariable logistic regression model was used to assess the associated factors.

RESULTS

Uncontrolled SE occurred in 37 out of 220 patients (17%). Persistent seizures at admission, higher SAPS II and central nervous system infection were associated with a higher risk of uncontrolled SE. Acute toxic or metabolic etiologies were associated with a decreased risk of uncontrolled SE. In a supplementary analysis, decrease of albumin blood levels was associated with uncontrolled SE. Uncontrolled SE was associated with a poor functional outcome and mortality at 90 days.

CONCLUSIONS

Seventeen percent of patients with a GCSE requiring MV suffered from uncontrolled SE. Etiology and persistent seizures at admission were the main predictors of uncontrolled SE. Patients with uncontrolled SE had a longer duration of sedation and MV, a poor functional outcome and a higher mortality. Further studies are required to determine the impact of continuous electroencephalogram monitoring on the clinical course.

Non-Animal Stabilized Hyaluronic Acid (NASHA) Gel Marker vs. Surgical Clips for Tumor Bed Delineation in Breast Cancer Using MR-Simulation

PURPOSE/OBJECTIVE(S)

Consistent delineation of the tumor bed (TB) after breast conserving surgery (BCS) is critical and remains a challenge with increasing prevalence of oncoplastic surgeries. Clips are generally used to help TB identification on CT-simulation but they are not well identified on MR-simulation. The aim of this study is to assess whether the use of NASHA gel with MR-simulation yields similar interobserver variability (inter-OV) compared to clips with CT-simulation.

MATERIALS/METHODS

This prospective single arm feasibility study included patients eligible for BCS. After lumpectomy, the surgeon placed both clips (>5) and NASHA gel drops as markers to define the TB. Patients underwent CT and MRI simulation scans. Five radiation oncologists and one radiologist delineated the TB aided by clips on CT, and gel on MRI. The observers also assessed the visibility and utility of the gel (scale from 1 to 10), as well as the cavity visualization score (CVS, scale from 1 to 5). The primary endpoint was the inter-OV of the delineated TB using the overlap difference of contours using clips and CT versus gel and MRI, with the conformity index measured according to the pair definition of the Dice Similarity Coefficient (DSC).

RESULTS

Of the 35 patients recruited, 30 were eligible for inter-OV analysis of TB delineation and 5 patients required further breast surgery for positive margins. One third of the eligible patients underwent an oncoplastic procedure. There were no significant differences between inter-OV of delineated TB using clips and CT versus gel and T2-weighted MRI with the mean DSC (0.60 vs 0.62, p = 0.364). The observers reported higher usefulness of gel in patients with an oncoplastic procedure than not (median US 8.2 vs 6.6, p = 0.024), and higher visibility of gel in patients who had their scans within 6 weeks than beyond post-op (median VS 8.1 vs 6.1, p = 0.013). When the CVS was higher (3-5), the median US of gel was lower (5.9 vs 7.8, p = 0.004), and the conformity index of clip and CT delineated TB was higher (median DSC 0.72 vs 0.53, p <0.001). Interestingly, a higher CVS did not lead to significantly higher conformity index of gel and T2-weighted MR delineated TB (mean DSC 0.67 vs 0.58, p = 0.073). NASHA gel injection added a median of 3 minutes to the operating theatre (OT) time and was rated as 'easy' in 89% of cases by surgeons. There were no immediate adverse events (AE) in OT, while 2 of 35 patients later experienced a grade 3 AE - hematoma which required evacuation in OT day 1 post-BCS, and infected seroma which required drainage and washout in OT 2 months post-BCS and axillary dissection. These reflect common risks with standard BCS and are not clearly attributed to gel injection alone.

CONCLUSION

Use of NASHA gel leads to similar inter-OV of BC TB delineation compared to >5 clips. NASHA gel is hence a reliable alternative to clips when MR-simulation is used.

Immune Checkpoint Inhibition and Single Fraction Stereotactic Radiosurgery in Non-Small Cell Lung Cancer Brain Metastases: An International Multicenter Study of 395 Patients

PURPOSE/OBJECTIVE(S)

Brain metastases most commonly arise from non-small cell lung cancer (NSCLC). In recent years, immune checkpoint inhibitors (ICI) have demonstrated improvements in overall survival (OS) in NSCLC. However, concerns remain about the risk of radiation necrosis (RN) when ICI are administered with stereotactic radiosurgery (SRS).

MATERIALS/METHODS

Logistic regression was used to evaluate prognostic factors associated with the development of any grade RN and symptomatic RN. Cumulative incidence of RN was evaluated using competing risks analysis and the Fine and Gray model, where the null hypothesis was rejected for p < 0.05.

RESULTS

There were 395 patients with 2,513 brain metastases treated across 11 international institutions included in the analysis. The median follow-up was 14.2 months. Median patient age was 67 years (Interquartile Range [IQR]: 61-73), 53.4% were male, the median Karnofsky Performance Status was 80 (IQR: 80-90), and 88.6% has active extracranial disease at the time of SRS. The median margin dose was 19 Gy (IQR: 18-20), 97.5% of patients were treated on the Gamma Knife ®, 3.8% underwent prior whole brain radiation therapy (WBRT). The median V12 Gy was 5.2 cm3 and 36.5% of patients had a V12 Gy ≥ 10 cm3, anti-PD-1 agents were administered in 91.6% of patients. A V12 Gy ³ 10 cm3 was associated with an increased risk of developing any grade RN; odds ratio (OR): 2.12, p = 0.04 and OR: 2.18; p = 0.03 on univariable and multivariable analysis, respectively. Similarly, a V12 Gy ≥ 10 cm3 was associated with an increased risk of developing symptomatic RN; OR: 3.80, p = 0.003 and OR: 3.95; p = 0.003 on univariable and multivariable analysis, respectively. Receipt of concurrent ICI and prior WBRT were not statistically significant. At 1-year, the cumulative incidence of any grade and symptomatic RN was 4.8% and 3.8%, respectively. The cumulative incidence of any grade RN was 3.8% vs. 5.3% for the concurrent and non-concurrent groups at 1-year, respectively (p = 0.35). The cumulative incidence of symptomatic RN was 3.8% vs. 3.6% for the concurrent and non-concurrent groups at 1-year, respectively (p = 0.95).

CONCLUSION

The risk of any grade and symptomatic RN following SRS and ICI administration for NSCLC brain metastases increases as the V12 Gy exceeds 10 cm3. Concurrent ICI and SRS does not appear to increase this risk. Radiosurgical planning techniques should aim to minimize the V12 Gy.

Selected-Lesion SRS as a Novel Strategy in Treatment of Patients with Multiple Brain Metastases

PURPOSE/OBJECTIVE(S)

With the increasing use of intracranial SRS (SRS) for treatment of patients with >10-15 brain metastases treatment; debate remains in the literature about how these patients should be treated. While many advocate for treatment of all lesions with either SRS or whole brain radiation therapy (WBRT), several groups are considering selected-lesion SRS (SL-SRS) where only a subset of intracranial lesions are treated. However, the current practice patterns of SL-SRS are not known.

MATERIALS/METHODS

A survey of 19 questions was created using open-ended and multiple-choice style questions on SL-SRS practices and indications. The survey was distributed to providers in the US and internationally who perform SRS frequently. Ten out of 50 institutions provided responses reflecting the practices of 16 providers. Descriptive statistics was used to compare answers to each question when applicable including percentages and ranges.

RESULTS

SL-SRS was performed at 8/10 institutions, (5 out of 6 US institutions and 3 out of 4 international institutions). Only 2 institutions had established clinical indications for SL-SRS (one in the US and one internationally) and one additional US institution reported clinical trials that require SL-SRS to study efficacy of CNS penetrating targeted therapies. One program reported research protocols for untreated brain metastases that would take priority over SL-SRS (program outside the US). Size of the lesion was cited as the most important factor (90%) when deciding to treat any single lesion. Next, lesion location and focal signs/symptoms were both considered moderately important. 80% ranked distance from prior SRS as the least important factor. Perilesional edema was also less important at most programs (90%). Lesion location and presence of symptoms were also considered important. There were several factors that would encourage providers to consider SL-SRS in a patient. Prior WBRT; progressing systemic disease and CNS-penetrating drug option available; and progressing systemic disease and immunotherapy option available were the most common responses. Most respondents cited "specific request by medical oncology" as well as "cooperative studies in this topic" as factors that might push them towards SL-SRS. Several institutions specified factors beyond the listed options. One institution reported that for patients with >20 lesions, they treated the largest lesions with SRS then follow with WBRT, termed the "pre-WBRT boost." Progression of untreated lesions was the most common reason why providers would bring back patients for additional treatment.

CONCLUSION

The responses to this survey demonstrate that patients with >15-20 intracranial lesions, prior WBRT, and worsening systemic disease with CNS penetrating systemic therapies available are being considered for SL-SRS.

Fréquence des acrosyndromes chez les patients avec infection sévère à SARS-CoV-2 en réanimation

Introduction

De nombreuses manifestations cliniques dermatologiques ont été rapportées durant la pandémie mondiale de la COVID-19. Parmi elles, des phénomènes d’acrosyndromes ont été décrits, principalement chez des patients suspects d’infection par SARS-Cov-2 mais asymptomatiques ou pauci-symptomatiques. Peu d’études se sont intéressées à ces manifestations chez les patients admis en réanimation. Notre objectif était donc d’évaluer la fréquence instantanée des manifestations acrales cutanées chez les patients sévères atteints de la COVID19 admis en réanimation.

Matériel et méthodes

Nous avons réalisé une étude observationnelle et prospective, réalisée du 5 au 6 mai 2020. Tout patient adulte hospitalisé en réanimation au CHU de Lille dans le cadre de la COVID19 était inclus et bénéficiait d’un examen systématique du tégument par un dermatologue sénior.

Résultats

Au total, 39 patients ont été examinés (34 hommes, 5 femmes) avec un âge moyen de 60,6 ans. Aucun patient n’avait présenté de symptôme dermatologique au début de la maladie. La durée médiane d’hospitalisation en réanimation était de 35 jours [21-41] ; 35 patients (90 %) avaient reçu un support ventilatoire par intubation oro-trachéale et 21 (54 %) un support circulatoire par amines vasopressives. Nous avons observé des manifestations cutanées acrales chez 11 patients (28 %) : lésions nécrotiques (5/11, 45 %), bulles hémorragiques (3/11, 27 %), livedo (1/11, 9 %), érosions (1/11, 9 %), hémorragies sous unguéales (2/11, 18 %). Un patient présentant à la fois des lésions nécrotiques et des érosions cutanées. Aucun patient ne présentait de manifestations à type d’engelure ou pseudo-engelure. Il n’y avait pas de différence significative entre les patients avec et sans manifestation acrale concernant la durée d’hospitalisation et les complications thromboemboliques, les symptômes initiaux, et les caractéristiques de base des patients excepté l’IMC moyen plus bas chez les patients avec manifestations acrales. La durée moyenne de la maladie était significativement plus longue et davantage de médicaments vasoactifs ont été administrés aux patients présentant des manifestations cutanées acrales, suggérant une gravité plus élevée de la maladie dans ce groupe et pouvant être en lien avec les manifestations observées.

Discussion

Nous rapportons une série de manifestations cutanées acrales chez seulement 28 % des patients pris en charge en réanimation au moment de l’étude. Ces manifestations sont variées et peu spécifiques. Aucune manifestation à type d’engelure n’était observée contrairement aux patients suspects de formes pauci ou asymptomatiques et inconstamment confirmées sur le plan sérologique ou moléculaire. Sur le plan physiopathologique, plusieurs hypothèses sont avancées comme une réponse immune antivirale de type interféron. Des études sont nécessaires afin de mieux comprendre les mécanismes à l’origine de ces manifestations.

Factors influencing the outcome of stereotactic radiosurgery in patients with five or more brain metastases

Background Stereotactic radiosurgery (srs) for patients with 5 or more brain metastases (bmets) is a matter of debate. We report our results with that approach and the factors influencing outcome.Methods In the 103 patients who underwent srs for the treatment of 5 or more bmets, primary histology was nonsmall- cell lung cancer (57% of patients). All patients were grouped by Karnofsky performance status and recursive partitioning analysis (rpa) classification. In our cohort, 72% of patients had uncontrolled extracranial disease, and 28% had stable or responding systemic disease. Previous irradiation for 1–4 bmets had been given to 56 patients (54%). The mean number of treated bmets was 7 (range: 5–19), and the median cumulative bmets volume was 2 cm3 (range: 0.06–28 cm3).Results Multivariate analyses showed that stable extracranial disease (p < 0.001) and rpa (p = 0.022) were independent prognostic factors for overall survival (os). Moreover, a cumulative treated bmets volume of less than 6 cm3 (adjusted hazard ratio: 2.54; p = 0.006; 95% confidence interval: 1.30 to 4.99) was associated with better os. The total number of bmets had no effect on survival (p = 0.206). No variable was found to be predictive of local control. The rpa was significant (p = 0.027) in terms of distant recurrence.Conclusions Our study suggests that srs is a reasonable option for the management of patients with 5 or more bmets, especially with a cumulative treatment volume of less than 6 cm3.

Factors influencing the outcome of stereotactic radiosurgery in patients with five or more brain metastases

Background

Stereotactic radiosurgery (srs) for patients with 5 or more brain metastases (bmets) is a matter of debate. We report our results with that approach and the factors influencing outcome.

Methods

In the 103 patients who underwent srs for the treatment of 5 or more bmets, primary histology was non-small-cell lung cancer (57% of patients). All patients were grouped by Karnofsky performance status and recursive partitioning analysis (rpa) classification. In our cohort, 72% of patients had uncontrolled extracranial disease, and 28% had stable or responding systemic disease. Previous irradiation for 1-4 bmets had been given to 56 patients (54%). The mean number of treated bmets was 7 (range: 5-19), and the median cumulative bmets volume was 2 cm³ (range: 0.06-28 cm³).

Results

Multivariate analyses showed that stable extracranial disease (p < 0.001) and rpa (p = 0.022) were independent prognostic factors for overall survival (os). Moreover, a cumulative treated bmets volume of less than 6 cm³ (adjusted hazard ratio: 2.54; p = 0.006; 95% confidence interval: 1.30 to 4.99) was associated with better os. The total number of bmets had no effect on survival (p = 0.206). No variable was found to be predictive of local control. The rpa was significant (p = 0.027) in terms of distant recurrence.

Conclusions

Our study suggests that srs is a reasonable option for the management of patients with 5 or more bmets, especially with a cumulative treatment volume of less than 6 cm³.

Real-time polymerase chain reaction detection of Lichtheimia species in bandages associated with cutaneous mucormycosis in burn patients

BACKGROUND

Cutaneous mucormycoses, mainly due to Lichtheimia (Absidia), have occurred on several occasions in the Burn Unit of the University Hospital of Lille, France.

AIM

To investigate the potential vector role of non-sterile bandages used to hold in place sterile gauze used for wound dressing.

METHODS

Mycological analysis by conventional culture, Mucorales real-time polymerase chain reaction (qPCR), and Lichtheimia species-specific qPCR were performed on eight crepe and six elasticized bandages that were sampled on two independent occasions in March 2014 and July 2016. Characteristics of the seven Lichtheimia mucormycoses which occurred in burn patients between November 2013 and July 2016 were also collected to assess the epidemiological relationship between potentially contaminated bandages and clinical infections.

FINDINGS

One Lichtheimia corymbifera strain was isolated from a crepe bandage by culture, and Lichtheimia spp. qPCR was positive in six out of eight crepe and four out of six elasticized bandages. Using species-specific qPCR, Lichtheimia ramosa, Lichtheimia ornata, and L. corymbifera were identified in six out of ten, five out of ten, and four out of ten bandages, respectively. In patients with mucormycosis, L. ramosa and L. ornata were present in five and two cases, respectively.

CONCLUSION

Our data support the utility of Mucorales qPCR for epidemiological investigations, the potential role of these bandages in cutaneous mucormycoses in burn patients in our centre, and, consequently, the need for sterile bandages for the dressing of extensive wounds.

Tumoural portal vein thrombosis

Purpose: Intrahepatic thrombus is usually associated with either cirrhosis or hepato-cellular carcinoma (HCC). Most HCCs enhance after the administration of MnDPDP (Teslascan). Our objective was to analyze the enhancement characteristics of tumour portal vein thrombi.

Material and Methods: Thrombi affecting the main or segmental portal veins (17 cases) and the suprahepatic inferior vena cava (1 case) were retrospectively selected from a series of 128 patients studied with MR imaging before and after the administration of MnDPDP. Enhancement was assessed qualitatively and quantitatively.

Results: All tumour thrombi enhanced after MnDPDP administration. The enhancement was more conspicuous in the GRE images. On the quantitative evaluation, the portal thrombus enhancement was greater for GRE images than SE images. Portal thrombi enhanced more than the liver and the HCCs. There was a significant difference between the enhancement of the HCCs and the thrombi with both MR imaging techniques.

Conclusion: The greater enhancement of the tumour thrombus associated with the liver and HCC may suggest that other mechanisms, apart from accumulation of the contrast medium within the hepatocytes inside the thrombi, are involved in thrombus enhancement.

Percutaneous Fine Needle Aspiration Cytology and Biopsy in the Diagnosis and Classification of Lymphoma: Clinical Evaluation

In some patients with suspected de novo or recurrent lymphoma, the absence of a palpable mass or peripheral lymph node enlargement can be a diagnostic challenge. We report our experience of fine needle aspiration (FNA) and biopsy in the management of 47 consecutive patients investigated in our institution over a period of 4 years. Lymphoma was suspected in 32 cases, and recurrent disease in 15 cases. Cytology was performed in all patients and biopsy in 16 patients, when a safe approach was possible. The specimens were obtained with computed tomography guidance and were diagnostic by cytology in 85% of cases: 28 patients had a newly diagnosed lymphoma and 3 had recurrent disease; residual fibrosis was diagnosed in 2 cases. Five patients with a previously diagnosed lymphoma had a new neoplasm: lung carcinoma: 3, renal adenocarcinoma: 1, metastatic lymph nodes: 1. One patient had non-neoplastic intercurrent disease (pulmonary nocardiosis). In 7 patients, no conclusive tissue was obtained (acellular: 1, blood: 3, necrosis: 3). In one case of suspected recurrent disease, a false-positive result was obtained. Cytology always allowed distinction between non-Hodgkin's lymphoma (NHL) and Hodgkin's disease (HD), with attempts to subclassify NHL according to the International Working Formulation. In 12 patients, immunochemical studies could be performed for immunologic subclassification of lymphoma on the basis of cytology (n = 6) and biopsy (n = 6). Our results show that percutaneous fine needle aspiration cytology is a reliable method for the diagnosis and classification of lymphoma, and immunologic studies can be performed on cytology alone if biopsy is unsafe.

Kinetics and pattern of viral excretion in biological specimens of two MERS-CoV cases

•

Lower respiratory tract excretion of MERS-CoV can be observed for more than one month.

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Viral excretion in multiple organs is possible, including viraemia.

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Prolonged infection prevention and control measures are necessary.

•

Prolonged monitoring of respiratory excretion seems necessary.

Background

Middle East respiratory syndrome coronavirus (MERS-CoV) is an emerging coronavirus involved in severe acute respiratory distress syndrome (ARDS) and rapid renal failure. Hospital outbreak and nosocomial transmission were reported, however, several issues remain on the viral excretion course.

Objectives

Describe the kinetics and pattern of viral excretion in two infected patients.

Study design

After the initial diagnosis, blood, urine, rectal and respiratory samples were collected regularly, aliquoted and stored at −80 °C. Real-time reverse transcriptase polymerase chain reaction assay targeted the UpE and Orf1a regions of the MERS-CoV genome.

Results

In patient 1, who died of refractory ARDS and renal failure, MERS-CoV RNA was detected in pharyngeal and tracheal swabs, as well blood samples and urine samples until the 30th day. Rectal swabs were negative. Patient 2 also developed multiple-organ failure, but survived, with persisting renal insufficiency (creatinine clearance at 30 mL/min) and persistent interstitial syndrome albeit weaned off mechanical ventilation and no longer requiring oxygen. Tracheal aspirations were positive until the 33rd day, while nasopharyngeal swabs were negative. All other biological samples were negative.

Discussion

Lower respiratory tract excretion of MERS-CoV could be observed for more than one month. The most severely ill patient presented an expression of the virus in blood and urine, consistent with a type-1 interferon mediated immunological response impaired in patient 1, but developed by patient 2. These results suggest that infection control precautions must be adequately evaluated in clinical wards and laboratories exposed to MERS-CoV.

Accuracy of leptin serum level in diagnosing ventilator-associated pneumonia: a case-control study

BACKGROUND

Undernutrition causes a reduction of body-fat mass and a decrease in the circulating concentration of leptin which impairs the production of proinflammatory cytokines and increases the incidence of infectious diseases. The main objective of this study was to determine whether leptin deficiency is a risk factor for ventilator-associated pneumonia (VAP).

METHODS

This prospective observational case-control study was conducted in a university ICU during a 2-year period. Patients with VAP (cases) were matched (1:1) to patients without VAP (controls) according to all the following criteria: age, gender, SAPS II, and duration of ICU stay before VAP occurrence. In all patients leptin, C-reactive protein (CRP) and procalcitonin (PCT) were measured at ICU admission, and twice a week. In addition, in cases, leptin, CRP and PCT were also measured on the day of VAP diagnosis.

RESULTS

Eighty-six cases were matched with 86 controls. No significant difference was found in leptin and PCT levels between cases and controls. CRP level was significantly higher on the day of VAP in cases compared with controls (99 vs. 48 mg/L, P=0.001). Combination of CRP-leptin (CRP ≥78 mg/L and leptin ≥6.2 ng/mL on the day of VAP) was significantly (P=0.009) associated with VAP in univariate analysis. Multivariate analysis identified the combination of CRP-leptin (OR [95% CI] 3.08 [1.18-8.04], P=0.003), LOD score (1.27 [1.08-1.48], P=0.003), neuromuscular-blockers use (6.6 [2.03-21.7], P=0.002), and reintubation (3.3 [1.14-9.6], P=0.027) as independent risk factors for VAP.

CONCLUSION

In our study, leptin level was not associated with VAP occurrence. Further studies are needed to confirm our results, and to define the exact inflammatory role of leptin, and its interest as a biomarker in ICU patients.

[Ten practical issues concerning acute poisoning with carbon monoxide in pregnant women]

BACKGROUND

The poisoning of carbon monoxide (CO) is the leading cause of death by poisoning in France. Its consequences are potentially serious to the fetus. Literature is ancient and little known.

PURPOSE AND METHOD

Make an inventory of knowledge about carbon monoxide poisoning during pregnancy.

RESULT

The CO causes maternal then fetal tissue hypoxia primarily by binding to hemoglobin with which it has a high affinity. Its transplacental passage may cause fetal harm, predominantly in the brain. Severity seems correlated with maternal symptoms during exposure. In the absence of maternal symptoms, however, the available data are reassuring. Hyperbaric oxygen therapy may reduce the risk to the fetus.

DISCUSSION

Oxygen therapy should be offered in all cases of CO poisoning, especially if there are maternal symptoms during exposure. In addition, a fetal echography directed on the cephalic pole - even a fetal magnetic resonance imaging three weeks after exposure - should also be proposed.

Theoretical shock sensitivity index for explosives

On the basis of simple physical arguments, the ratio of the weakest bond dissociation energy of nitro compounds to their decomposition enthalpy per covalent bond is put forward as a practical shock sensitivity index. Without any empirical fitting, it correlates remarkably well (R ≥ 0.95) with shock sensitivity data reported for 16 molecules spanning the most significant families of explosive compounds. This result supports the underlying assumption that this property depends on the ability of decomposition events to propagate into the material. It demonstrates that sensitivity-structure relationships should take the energy content of the material into account. A linear regression against the present sensitivity index yields a predictive method with better performance than previous ones. Its sounder physical bases provide new insight into the molecular determinants of sensitivity and a compelling explanation for the sensitivity values reported for TATB and FOX-7.

Inductive modeling of physico-chemical properties: flash point of alkanes

The problem of predicting flash points (T(*)) of alkanes from their molecular formula is revisited. Starting from an examination of the dependence of T(*) on the length of the carbon chain for n-alkanes, a new model is proposed. Despite its extreme simplicity, it performs better than published alternatives based on advanced regression techniques. This illustrates the interest of an inductive approach to quantitative structure-property relationships, whereby a model is first developed for restricted series of simple compounds before being generalized.

Transmission of chloroplast genes in triploid and tetraploid zygospores of Chlamydomonas reinhardtii: Roles of mating-type gene dosage and gametic chloroplast DNA content

Diploid clones homozygous (mt(+)/mt(+) or mt(-)/mt(-)) or heterozygous (mt(+)/mt(-); phenotypically mt(-)) for the mating-type locus and homoplasmic for a chloroplast marker conferring resistance to an antibiotic were isolated by artificially induced cell fusion or sexual mating. These diploids were crossed with haploid or diploid strains of opposite mating type and carrying another chloroplast marker. The transmission of the chloroplast genes was analyzed in the triploid and tetraploid zygospores in comparison with diploid zygospores used as controls. The transmission was almost exclusively maternal (mt(+)) (>94%) in the crosses mt(+) x mt(-), mt(+)/mt(+) x mt(-), and mt(+)/mt(+) x mt(-)/mt(-). The transmission was preferentially maternal (>76%) in the crosses mt(+) x mt(-)/mt(-) whereas in the crosses mt(+) x mt(+)/mt(-), <50% of the zygospores transmitted the chloroplast allele of maternal (mt(+)) origin. The zygospores produced in crosses mt(+)/mt(+) x mt(+)/mt(-) transmitted the alleles from both parents in >60% of cases. The results show that (i) the presence of one mt(+) allele in the mt(+)/mt(-) (phenotypically mt(-)) diploid gametes and (ii) the higher amount of chloroplast DNA molecules (input) present in the diploid gametes versus the haploid ones favor the transmission of the chloroplast allele contributed by these gametes. Moreover, because the zygospores issued from crosses mt(+)/mt(+) x mt(-) and mt(+) x mt(+)/mt(-) were genotypically identical mt(+)/mt(+)/mt(-)) but behaved very differently in their chloroplast gene transmission, it was concluded that the molecular events leading to preferential elimination of paternal DNA copies must occur before the fusion of nuclei or chloroplasts in the newly formed zygotes.