An Isotopic Exchange Kinetic Model to Assess the Speciation of Metal Available Pool in Soil: The Case of Nickel

In this study an innovative approach is proposed to predict the relative contribution of each mineral phase to the total metal availability in soils, which, in other words, could be called the available metal fractionation. Through the use of isotopic exchange kinetics (IEK) performed on typical Ni bearing phases (i.e., two types of serpentines, chlorite, smectite, goethite, and hematite) the isotopic exchange and metal-solid interaction processes are connected, considering both the thermodynamic and kinetic aspects. Results of Ni IEK experiments on mineral phases are fitted with a pseudo-first order kinetic model. For each Ni bearing phase, this allows to (i) determine the number and size of exchangeable pools (E_Ni(i)), (ii) assess their corresponding kinetic constants (k_(i)), and (iii) discuss the mechanism of Ni isotopic exchange at mineral surfaces. It is shown that all the phases investigated, with the only exception of hematite, present at least two distinct reactive pools with significantly different k_(i) values. Results suggest also that metal involved in outer-sphere complexes would display isotopic exchange between 100 and 1000 times faster than metal involved in inner-sphere complexes, and that the presence of high and low affinity sites may influence the rate of isotopic exchange up to 1 order of magnitude. Moreover, the method developed represents a tool to predict and estimate Ni mobility and availability in natural soil samples on the basis of soil mineral composition, providing information barely obtained with other techniques.

Smoking cessation attempts: is it useful to treat hard core smokers?

Background

Hard core smokers have been studied in many countries but only a few trials have compared the effectiveness of smoking cessation with other smokers. The objective of this study was to compare the frequencies of success in smoking cessation between hard-core smokers and other smokers.

Methods

Data were collected in Clermont-Ferrand from the Emile Roux dispensary ‘Pneumology and Tobaccology Centre’ between 1999 and 2009. Assistance with smoking cessation was proposed to 1367 patients but only 1296 patients were included: 219 HCS and 1077 other smokers. Smoking cessation was considered a success when patients were abstinent 6 months after the beginning of cessation. The profiles of the two types of smokers were compared using Chi square test and Student’s t test. Multivariate logistic regression was used to investigate the association between the smoking cessation result and the type of smokers.

Results

HCS more frequently consumed other psychoactive substances (41.1 % vs 25.7 % for other smokers; p < 0.001). Current depression was more frequent in HCS (46.6 % vs 34.8 % for other smokers; p = 0.001). Smoking cessation was less frequent in HCS (45.2 % vs 56.5 % for other smokers ; p = 0.002). In multivariate analysis, after controlling for other factors, the frequency of smoking cessation was not significantly associated with the type of smokers (p = 0.47). After limiting to initial factors (present before the beginning of smoking cessation), the frequency of smoking cessation was still not significantly associated with the type of smokers (p = 0.78).

Conclusion

Smoking cessation is possible for hard core smokers, who should be treated as other types of smokers taking into account other factors:the problem is how to encourage them to try to stop smoking.

Intrauterine balloon tamponade for management of severe postpartum haemorrhage in a perinatal network: a prospective cohort study

OBJECTIVE

To evaluate the effectiveness of intrauterine balloon tamponade (IUBT) for management of severe postpartum haemorrhage (PPH). To identify the factors predicting IUBT failure.

DESIGN

Prospective cohort study.

SETTING

Ten maternity units in a perinatal network.

POPULATION

Women treated by IUBT from July 2010 to March 2013.

METHODS

The global IUBT success rate was expressed as the number of women with severe PPH who were successfully treated by IUBT divided by the total number treated by IUBT. IUBT failure was defined as the need for arterial embolisation or surgery. Logistic regression analysis was used to estimate factors predicting IUBT failure.

MAIN OUTCOME MEASURES

Global IUBT success rate. Factors associated with IUBT failure.

RESULTS

Intrauterine balloon tamponade was attempted in 226 women: 171 after vaginal delivery (VD) (75.7%) and 55 during or after caesarean delivery (CD) (24.3%). The global success rate was 83.2% (188/226) and was significantly higher after VD (152/171, 88.9%) than CD (36/55, 65.5%, P < 0.01). The percentage of CD was significantly higher in the failure group (50.0 versus 19.1%, P < 0.01), as was mean (SD) estimated blood loss before IUBT: 1508 ± 675 ml versus 1064 ± 476, P < 0.01. Coagulopathy was significantly more frequent in the failure group (50.0% versus 17.2%, P < 0.01). CD [Odds ratio (OR) 3.5; 95% CI 1.6-7.6], estimated blood loss before IUBT (OR 3.2; 95% CI 1.5-6.8) and coagulopathy (OR 5.6; 95% CI 2.5-13.0) were predictive of IUBT failure.

CONCLUSION

Intrauterine balloon tamponade is an effective method for treating severe PPH. Early balloon deployment before the development of coagulopathy increases its success rate.

TWEETABLE ABSTRACT

Intrauterine balloon tamponade is effective for achieving haemostasis in intractable postpartum haemorrhages.

[Evaluation of the metrological quality of the medico-administrative data for perinatal indicators: A pilot study in 3 university hospitals]

BACKGROUND

In order to assess public health policies for the perinatal period, routinely produced indicators are needed for the whole population. In France, these indicators are used to compare the national public health policy with those of other European countries. French administrative and medical data (PMSI) are straightforward and reliable and may be a valuable source of information for research. This study aimed to measure the quality of PMSI data from three university health centers for core indicators in perinatal health.

METHOD

PMSI data were compared with medical files in 2012 from 300 live births after 22 weeks of amenorrhea, drawn at random from University Hospitals in Dijon, Paris and Nancy. The variables were chosen based on the Europeristat Project's core and recommended indicators, as well as those of the French National Perinatal survey conducted in 2010. The information gathered blindly from the medical files was compared with the PMSI data positive predictive value (PPV) and the sensitivity was used to assess data quality.

RESULTS

Data on maternal age, parity and mode of delivery as well as the rates of premature births were superimposable for the two sources. The PPV for epidural injection was 96.2% and 94.3% for perineal tears. Overall, maternal morbidity was underdocumented in the PMSI, so the PPV was 100.0% for pre-existing diabetes, 88.9% for gestational diabetes and 100.0% for high blood pressure with a rate of 9.0% in PMSI and 6.3% in the medical files. The PPV for bleeding during labor was 89.5%.

CONCLUSION

To conclude, PMSI data are apparently becoming more and more reliable for two reasons: on one hand, the importance of these data for budgetary promotion in hospitals; on the other, the increasing use of this information for statistical and epidemiological purposes.

[Comparison of British and French expatriate doctors' characteristics and motivations]

BACKGROUND

Migration of medical practitioners is rarely studied despite its importance in medical demography: the objective of this study was to analyze the characteristics and motivations of the French doctors settled in the United Kingdom and of the British doctors settled in France.

METHODS

This cross-sectional study was conducted using a self-completed questionnaire sent to all French doctors practicing in the United Kingdom (in 2005) and all British medicine doctors practicing in France (in 2009). The doctors were identified with official data from the National Medical Councils: 244 French doctors practicing in the United Kingdom and 86 British doctors practicing in France. The questionnaire was specifically developed to determine the reasons of moving to the other country, and the level of satisfaction after expatriation.

RESULTS

A total of 98 French doctors (out of 244) and 40 British doctors (out of 86) returned the questionnaire. Respondents were mainly general practitioners with a professional experience of 8 to 9 years. The sex ratio was near 1 for both groups with a majority of women among physicians under 50 years. The motivations were different between groups: French doctors were attracted by the conditions offered at the National Health Service, whereas British doctors were more interested in opportunities for career advancement, joining husband or wife, or favourable environmental conditions. Overall, the respondents considered expatriation as satisfactory: 84% of French doctors, compared with only 58% of British doctors, were satisfied with their new professional situation.

CONCLUSION

This study, the first in its kind, leads to a clearer understanding of the migration of doctors between France and the United Kingdom.