Comparative Recoveries of Naegleria fowleri Amoebae from Seeded River Water by Filtration and Centrifugation

Detection of pathogenic Naegleria fowleri in environmental water samples, which is necessary for the prevention of primary amoebic meningoencephalitis, generally requires concentrating the samples. Two concentration techniques, filtration and centrifugation, were used to study the recovery of N. fowleri, in vegetative or cystic form, that had been mixed with the two other thermotolerant Naegleria species, N. lovaniensis and N. australiensis. Counting of amoebae was performed by the most probable number method on 10 water replicates of 100 ml and 10 ml each. With both concentration methods, recovery was better for cysts than for trophozoites (53% ± 21% versus 5% ± 5% by filtration and 57% ± 25% versus 22% ± 5% by centrifugation). The recovery of Naegleria trophozoites by filtration was very low, and centrifugation was significantly better than filtration in recovery of Naegleria trophozoites (22% ± 5% versus 5% ± 5%; P < 0.001). For cysts, however, filtration appeared as efficient as centrifugation, with equivalent values for recovery (53% ± 21% versus 57% ± 25%; P > 0.7). Although the recovery of cysts of N. fowleri obtained by filtration (51% ± 24%) appeared higher than that by centrifugation (36% ± 23%), the difference was not significant (P > 0.1). Both concentration methods have highly variable recovery rates, making accurate quantification of low concentrations (<100/liter) of N. fowleri in the environment difficult.     

Low levels of extraneous agents in vaccine starting materials

There are different ways to define the concept of ‘low levels’ of extraneous agents in vaccines and vaccine starting materials, based on the amount of extraneous agents as such, the sensitivity of the detection method and the probability approach linked to the sampling method. None of these approaches, however, is entirely satisfactory – a general definition of a ‘low level’ cannot be provided. Since the main point is the safety of medicinal products, the risk analysis approach to ‘low level’ contaminations can be considered as a way to overcome the abovementioned deadlock. But as too many variables impact the risk analysis, it cannot be properly performed either. In practice, seeds are tested to show freedom from extraneous agents, the other raw materials are inactivated through a validated method. However, there are technical and regulatory limits in both cases, and neither testing nor inactivation entirely guarantees freedom from extraneous agents. Despite this unsatisfactory situation, it should be acknowledged that no truly significant disease outbreak linked to an extraneous agent has been identified until today. Regulatory actions are mainly undertaken when a sanitary problem occurs. In the end, companies remain responsible for their products.     

Verbal cues modulate hedonic perception of odors in 5-year-old children as well as in adults

The judgment of pleasantness/unpleasantness is the prominent reaction to the olfactory world. In human adults, the hedonic valence of odor perception is affected by various factors, among which is an individual's lexical knowledge about smells. The present study examined whether such top-down effects of lexical knowledge on hedonic judgment of olfactory input are similar in children (5-6 years) and adults (20-25 years). In both groups, the lexical knowledge was found to influence the perception of the least emotional (or most neutral) odors: the pleasantness of the smells of banana and mint was enhanced when participants were given the corresponding odor label before olfactory sensation. These results lend support to the notion that, during childhood, smells are not only encoded perceptually but that verbal encoding also steers contextual effects that may be prominent factors in the early memorization and categorization of odors.     

Flexible parametric modeling of survival from age at death data: A mixed linear regression framework

Many long-lived vertebrate species are under threat in the Anthropocene, but their conservation is hampered by a lack of demographic information to assess population long-term viability. When longitudinal studies (e.g., Capture-Mark-Recapture design) are not feasible, the only available data may be cross-sectional, for example, stranding for marine mammals. Survival analysis deals with age at death (i.e., time to event) data and allows to estimate survivorship and hazard rates assuming that the cross-sectional sample is representative. Accommodating a bathtub-shaped hazard, as expected in wild populations, was historically difficult and required specific models. We identified a simple linear regression model with individual frailty that can fit a bathtub-shaped hazard, take into account covariates, allow goodness-of-fit assessments and give accurate estimates of survivorship in realistic settings. We first conducted a Monte Carlo study and simulated age at death data to assess the accuracy of estimates with respect to sample size. Secondly, we applied this framework on a handful of case studies from published studies on marine mammals, a group with many threatened and data-deficient species. We found that our framework is flexible and accurate to estimate survivorship with a sample size of 300 . This approach is promising for obtaining important demographic information on data-poor species.     

Effects of high-frequency jet ventilation on arterial baroreflex regulation of heart rate

Fifteen anesthetized mechanically ventilated patients recovering from multiple trauma were studied to compare the effects of high-frequency jet ventilation (HFJV) and continuous positive-pressure ventilation (CPPV) on arterial baroreflex regulation of heart rate. Systolic arterial pressure and right atrial pressure were measured using indwelling catheters. Electrocardiogram (ECG) and mean airway pressure were continuously monitored. Lung volumes were measured using two linear differential transformers mounted on thoracic and abdominal belts. Baroreflex testing was performed by sequential intravenous bolus injections of phenylephrine (200 micrograms) and nitroglycerin (200 micrograms) to raise or lower systolic arterial pressure by 20-30 Torr. Baroreflex regulation of heart rate was expressed as the slope of the regression line between R-R interval of the ECG and systolic arterial pressure. In each mode of ventilation the ventilatory settings were chosen to control mean airway pressure and arterial PCO2 (PaCO2). In HFJV a tidal volume of 159 +/- 61 ml was administered at a frequency of 320 +/- 104 breaths/min, whereas in CPPV a tidal volume of 702 +/- 201 ml was administered at a frequency of 13 +/- 2 breaths/min. Control values of systolic arterial pressure, R-R interval, mean pulmonary volume above apneic functional residual capacity, end-expiratory pulmonary volume, right atrial pressure, mean airway pressure, PaCO2, pH, PaO2, and temperature before injection of phenylephrine or nitroglycerin were comparable in HFJV and CPPV. Baroreflex regulation of heart rate after nitroglycerin injection was significantly higher in HFJV (4.1 +/- 2.8 ms/Torr) than in CPPV (1.96 +/- 1.23 ms/Torr).(ABSTRACT TRUNCATED AT 250 WORDS)     

Semantic knowledge influences prewired hedonic responses to odors

Background

Odor hedonic perception relies on decoding the physicochemical properties of odorant molecules and can be influenced in humans by semantic knowledge. The effect of semantic knowledge on such prewired hedonic processing over the life span has remained unclear.

Methodology/Principal Findings

The present study measured hedonic response to odors in different age groups (children, teenagers, young adults, and seniors) and found that children and seniors, two age groups characterized by either low level of (children) or weak access to (seniors) odor semantic knowledge, processed odor hedonics more on the basis of their physicochemical properties. In contrast, in teenagers and young adults, who show better levels of semantic odor representation, the role of physicochemical properties was less marked.

Conclusions/Significance

These findings demonstrate for the first time that the biological determinants that make an odor pleasant or unpleasant are more powerful at either end of the life span.     

Cardiac Compression of Lung Lower Lobes after Coronary Artery Bypass Graft with Cardiopulmonary Bypass

Background

Atelectasis is a major cause of hypoxemia after coronary artery bypass grafting (CABG) and is commonly ascribed to general anesthesia, high inspiratory oxygen concentration and cardiopulmonary bypass (CPB). The objective of this study was to evaluate the role of heart-induced pulmonary compression after CABG with CPB.

Methods

Seventeen patients without pre-operative cardiac failure who were scheduled for coronary artery bypass graft underwent pre- and postoperative thoracic computed tomography. The cardiac mass, the pressure exerted on the lungs by the right and left heart and the fraction of collapsed lower lobe segments below and outside of the heart limits were evaluated on a computed tomography section 1 cm above the diaphragmatic cupola.

Results

In the postoperative period, cardiac mass increased by 32% (117±31 g versus 155±35 g, p<0.001), leading to an increase in the pressure that was exerted on the lungs by the right (2.2±0.6 g.cm⁻² versus 3.2±1.2 g.cm⁻², p<0.05) and left heart (2.4±0.7 g.cm⁻² versus 4.2±1.8 g.cm⁻², p<0.001). The proportion of collapsed lung segments beneath the heart markedly increased [from 6.7% to 32.9% on the right side (p<0.001) and from 6.2% to 29% on the left side (p<0.001)], whereas the proportion of collapsed lung segments outside of the heart limits slightly increased [from 0.7% to 10.8% on the right side (p<0.001) and from 1.5% to 12.6% on the left side (p<0.001)].

Conclusion

The pressure that is exerted by the heart on the lungs increased postoperatively and contributed to the collapse of subjacent pulmonary segments.     

Individual differences in odor imaging ability reflect differences in olfactory and emotional perception

We asked whether the large variability in odor imaging ability is underlain by interindividual differences in the processing of smells and emotion. Olfactory imaging ability, anhedonia level, and odor perception were measured in 40 subjects, using the Vividness of Olfactory Imagery Questionnaire (VOIQ), the Physical Anhedonia Scale, and the European Test of Olfactory Capabilities. "Good" olfactory imagers, defined primarily on the basis of the VOIQ, rated pleasant smells as more familiar and had lower anhedonia scores than "bad" olfactory imagers. Based on self-reported measures, these results suggest that, like olfactory perception, the mental imagery of smells is related to emotion and that, beyond their differences in vividness, good and bad olfactory imagers differ in their experience of emotion and long-term memory of smells.