Neurobiological insight into hyperbaric hyperoxia

AIM

Hyperbaric hyperoxia (HBO) is known to modulate aerobic metabolism, vasoreactivity and blood flow in the brain. Nevertheless, mechanisms underlying its therapeutic effects, especially in traumatic brain injury (TBI) and stroke patients, are debated. The present study aimed at investigating regional cerebral blood flow (rCBF) distribution during acute HBO exposure.

METHODS

Regional cerebral blood flow response was investigated in seven healthy subjects exposed to either normobaric normoxia or HBO with ambient pressure/inspired oxygen pressure of 101/21 and 250/250 kPa respectively. After 40 min at the desired pressure, they were injected a perfusion tracer and subsequently underwent brain single photon emission computed tomography. rCBF distribution changes in the whole brain were assessed by Statistical Parametric Mapping.

RESULTS

During HBO, an increased relative rCBF distribution was found in sensory-motor, premotor, visual and posterior cingulate cortices as well as in superior frontal gyrus, middle/inferior temporal and angular gyrus and cerebellum, mainly in the dominant hemisphere. During normobaric normoxia, a higher (99m) Tc-HMPAO distribution in the right insula and subcortical structures as well as in bilateral hippocampi and anterior cingulated cortex was found.

CONCLUSIONS

The present study firstly confirmed the rCBF distribution increase during HBO in sensory-motor and visual cortices, and it showed for the first time a higher perfusion tracer distribution in areas encompassed in dorsal attention system and in default mode network. These findings unfold both the externally directed cognition performance improvement related to the HBO and the internally directed cognition states during resting-state conditions, suggesting possible beneficial effects in TBI and stroke patients.

Gray matter volume alterations related to trait dissociation in PTSD and traumatized controls

OBJECTIVE

This study used voxel-based morphometry (VBM) to investigate brain structural alterations related to trait dissociation and its relationship with post-traumatic stress disorder (PTSD).

METHOD

Thirty-two subjects either developing (N = 15) or non-developing (N = 17) PTSD underwent MRI scanning and were assessed with the Dissociative Experience Scale (DES), subscales for pathological (DES-T) and non-pathological trait (DES-A) dissociation, and other clinical measures. Gray matter volume (GMV) was analyzed using VBM as implemented in SPM. PTSD and non-PTSD subjects were compared to assess brain alterations related to PTSD pathology, whereas correlation analyses between dissociation measures and GMV were performed on the whole sample (N = 32), irrespective of PTSD diagnosis, to identify alterations related to trait dissociation.

RESULTS

As compared to traumatized controls, PTSD subjects showed reduced GMV in the prefrontal cortex, hippocampus and lingual gyrus. Correlations with dissociation measures (DES, DES-T, and DES-A) consistently showed increased GMV in the medial and lateral prefrontal, orbitofrontal, parahippocampal, temporal polar, and inferior parietal cortices.

CONCLUSION

PTSD and dissociation seem to be associated with opposite volumetric patterns in the prefrontal cortex. Trait dissociation appears to involve increased GMV in prefrontal, paralimbic, and parietal cortices, with negligible differences between pathological and non-pathological dissociation.

Skin test concentrations for systemically administered drugs -- an ENDA/EAACI Drug Allergy Interest Group position paper

Skin tests are of paramount importance for the evaluation of drug hypersensitivity reactions. Drug skin tests are often not carried out because of lack of concise information on specific test concentrations. The diagnosis of drug allergy is often based on history alone, which is an unreliable indicator of true hypersensitivity.To promote and standardize reproducible skin testing with safe and nonirritant drug concentrations in the clinical practice, the European Network and European Academy of Allergy and Clinical Immunology (EAACI) Interest Group on Drug Allergy has performed a literature search on skin test drug concentration in MEDLINE and EMBASE, reviewed and evaluated the literature in five languages using the GRADE system for quality of evidence and strength of recommendation. Where the literature is poor, we have taken into consideration the collective experience of the group.We recommend drug concentration for skin testing aiming to achieve a specificity of at least 95%. It has been possible to recommend specific drug concentration for betalactam antibiotics, perioperative drugs, heparins, platinum salts and radiocontrast media. For many other drugs, there is insufficient evidence to recommend appropriate drug concentration. There is urgent need for multicentre studies designed to establish and validate drug skin test concentration using standard protocols. For most drugs, sensitivity of skin testing is higher in immediate hypersensitivity compared to nonimmediate hypersensitivity.

Physical and mental health, anxiety and depressive symptoms in caregivers of patients in vegetative state and minimally conscious state

Caregivers of patients in vegetative state and minimally conscious state play a crucial role in the process of taking care and, as previous studies reported, they can suffer of high burden and negative health outcomes. The aim of this national cross-sectional study was to assess whether physical and mental health of caregivers, considering gender differences, is related to the presence of depressive symptoms, anxiety, age and patient's disease duration. Four-hundred and eighteen caregivers, 294 women and 124 men, completed the State Trait Anxiety Inventory-Y, Beck Depression Inventory, second version and Short Form-12. Hierarchical multiple regression analyses were performed to evaluate to which extent depressive and anxiety symptoms predict physical and mental health. Men reported higher levels of mental health state, whereas physical health was not different across gender. High levels of anxiety symptoms were associated to negative mental health outcomes in both genders, whereas depressive symptoms were found to impact on female's mental and physical health only. A comprehensive and cost-effective screening of anxiety and depressive symptoms may help to identify determinants of health worsening in order to plan, when necessary, caregivers' support.

KEY PRACTITIONER MESSAGES

Female caregivers of patients in vegetative state and minimally conscious state have poorer levels of mental health, whereas physical health is similar to men's. Anxiety symptoms are related to negative mental health outcomes in both male and female caregivers, whereas depressive symptoms are found to impact on female mental and physical health only. It is essential to consider and assess depressive and anxiety symptoms as they may contribute to caregivers' health worsening. This knowledge can lead to plan more comprehensive and tailored caregivers' supports and a better care for patients.

Burden of caregivers of patients in Vegetative state and minimally conscious state

OBJECTIVES

To assess differences in the burden of caregivers of patients in Vegetative state (VS) and minimally conscious state (MCS).

MATERIALS AND METHODS

The Family Strain Questionnaire, Coping Orientations to Problem Experiences, Caregiver Needs Assessment, Short Form-12, Beck Depression Inventory and State-Trait Anxiety Inventory were used. Differences in psychological condition between caregivers of VS and MCS patients, with different disease duration and hosting facility were assessed with Kruskall-Wallis test and factors associated with the overall levels of burden with UNIANOVA.

RESULTS

In total, 487 participants were enrolled. Daily hours of care-giving is significantly associated with the overall level of burden perceived by caregivers (F = 4.099; P = 0.018). Strain, needs and frequency of use of coping strategies are substantially similar regardless of the patient's condition and distance from the acute event. Caregivers of post-acute patients reported low scores in mental health (median = 33.8; IQR = 23.1-47.6) and higher state of anxiety (median = 54; IQR = 45-62), whereas caregivers of long-term patients expressed more needs in social involvement (median = 19; IQR = 15-22).

CONCLUSIONS

Burden and distress were high for all caregivers of VS and MCS patients. As care-giving is a long-term commitment process, support to the caregiver should be guaranteed throughout the duration of the relative's disease despite the patient's diagnosis or place where the patient is hosted.

Efficacy of venom immunotherapy given every 3 or 4 months: a prospective comparison with the conventional regimen

BACKGROUND

Standard venom immunotherapy involves the administration of the maintenance dose every 4 to 6 weeks. This regimen may have adherence problems, especially in the long term; thus, extended intervals have been proposed.

OBJECTIVE

We prospectively compared the efficacy of 3- or 4-month extended maintenance dose vs the conventional regimen.

METHODS

Patients receiving immunotherapy with a single venom were offered the extended maintenance dose (EMD) and were then followed up for field re-stings. Only the re-stings by the insect for which the patients received immunotherapy were considered. A comparable group of patients receiving the conventional maintenance dose (CMD) was used for comparison by logistic regression analysis.

RESULTS

Seventy-six patients (60 male; mean age, 48 years) receiving the EMD were re-stung on 247 occasions by the insect for which they were receiving immunotherapy. The group receiving CMD included 110 patients (82 male; mean age, 44 years) certainly re-stung on 167 occasions by the specific insect. The percentage of re-sting without reaction was 93.5% in the EMD group and 81.5% in the CMD group, with a significant difference in favor of the former (P=.001). At logistic regression analysis, only age, but not maintenance dose protocol, was predictive of subsequent systemic reactions.

CONCLUSION

The EMD is as effective and safe as the CMD. An increased maintenance seems to be the best option in term of convenience and economic savings.

Geobiological constraints on Earth system sensitivity to CO₂ during the Cretaceous and Cenozoic

Earth system climate sensitivity (ESS) is the long-term (>10³ year) response of global surface temperature to doubled CO₂ that integrates fast and slow climate feedbacks. ESS has energy policy implications because global temperatures are not expected to decline appreciably for at least 10³ year, even if anthropogenic greenhouse gas emissions drop to zero. We report provisional ESS estimates of 3 °C or higher for some of the Cretaceous and Cenozoic based on paleo-reconstructions of CO₂ and temperature. These estimates are generally higher than climate sensitivities simulated from global climate models for the same ancient periods (approximately 3 °C). Climate models probably do not capture the full suite of positive climate feedbacks that amplify global temperatures during some globally warm periods, as well as other characteristic features of warm climates such as low meridional temperature gradients. These absent feedbacks may be related to clouds, trace greenhouse gases (GHGs), seasonal snow cover, and/or vegetation, especially in polar regions. Better characterization and quantification of these feedbacks is a priority given the current accumulation of atmospheric GHGs.

Children in vegetative state and minimally conscious state: patients' condition and caregivers' burden

Caring for children in vegetative state (VS) or minimally conscious state (MCS) challenges parents and impacts on their well-being. This study aims to evaluate caregivers' health condition, coping, anxiety and depression levels, and how these issues relate to children's disability. 35 children with VS and MCS were administered the disability rating scale (DRS) and 35 caregivers completed the Coping Orientations to Problem Experiences, Short Form-12, Beck Depression Inventory, and the Spielberger State-Trait Anxiety Inventory-Y. Children were mainly males (68.6%), hosted at domicile (77.1%), and diagnosed with VS (60%), with anoxic aetiology (45.7%). Caregivers were mainly mothers (85.7%), married (82.9%), and housewives (51.4%); 60% declared financial difficulties, and 82.9% provided full-time assistance. 57.2% reported depressive symptoms, poor mental health, and high level of state and trait anxiety. “Problem-oriented” (P < 0.001) and “emotional-oriented” (P < 0.001), were more adopted than “potentially dysfunctional” ones. DRS scores (mean = 22.0; SD = 1.9) did not significantly correlate to any psychological measure. Rehabilitative programs for children with SV and SMC should also provide interventions on surrounding systems: improving the network of psychological support and social assistance may decrease the burden of caregivers and, in turn, improve caring abilities and children quality of life.

Extraction and mass spectrometry identification of a major peach allergen Pru p 1

BACKGROUND

Peach allergy can be caused by the allergen Pru p 1. This occurs by cross-reactivity with the homologous birch pollen allergen Bet v 1. However, the direct identification of Pru p 1 as an immunoglobulin E (IgE)-binding protein extracted from peach fruit has never been reported.

RESULTS

Phosphate-buffered saline (PBS) and phenol extractions were applied to solubilise the proteins from peach peel and pulp, and IgE immunoblotting with sera of individual peach-allergic patients was used to detect the potential allergens. Most of the patients showed binding to an 18 kDa band in IgE immunoblotting performed with the phenolic extracts of peach peel and pulp, but not when the PBS extracts were used. Mass spectrometry of the 18 kDa spot excised from a two-dimensional electrophoretic gel showed this protein to correspond to the peach allergen Pru p 1.

CONCLUSION

Phenol extraction was necessary to detect by IgE immunoblotting a major peach allergen, which showed very low extractability with PBS, indicating the appropriateness of adopting different extraction procedures to identify plant allergens. The 18 kDa peach protein was definitively identified as the Bet v 1-homologous peach allergen Pru p 1.

Self-rating scales assessing subjective well-being and distress correlate with rCBF in PTSD-sensitive regions

BACKGROUND

The aim of this study was to investigate the distribution of the regional cerebral blood flow (rCBF) in occupational-related post-traumatic stress disorder (PTSD) subjects and to seek possible correlations between brain perfusion and self-rating scales (SRS) in order to cross-check their diagnostic value and to look for their neural correlates.

METHOD

A total of 13 traumatized underground and long-distance train drivers developing (S) and 17 not developing (NS) PTSD who had experienced a 'person under train' accident or who had been assaulted at work underwent clinical assessment and 99mTc-HMPAO SPECT imaging during autobiographical trauma scripts. Statistical parametric mapping was applied to analyse rCBF changes in S as compared with NS and to search for correlations between rCBF and the administered SRS scores, modelling age, months to SPECT and the ratio 'grey matter/intra-cranial volume' as nuisance variables.

RESULTS

Significantly higher activity was observed during trauma script in left posterior and anterior insula, posterior cingulate, inferior parietal lobule, precuneus, caudate and putamen in PTSD subjects as compared with the trauma-exposed control group. Impact of Event Scale and World Health Organisation (10) Well-Being Index scores highly correlated with tracer uptake to a great extent in the same regions in which rCBF differences between S and NS were found.

CONCLUSIONS

These findings support the involvement of insular, cingulate and parietal cortices (as well as the basal ganglia) in the pathogenesis of PTSD and in the processing of related subjective well-being and distress.

Impact of acute hypobaric hypoxia on blood flow distribution in brain

AIM

Acute hypobaric hypoxia is well known to alter brain circulation and to cause neuropsychological impairment. However, very few studies have examined the regional changes occurring in the brain during acute exposure to extreme hypoxic conditions.

METHODS

Regional cerebral blood flow (rCBF) response to hypoxia was investigated in six healthy subjects exposed to either normobaric normoxia or hypobaric hypoxia with ambient pressure/inspired oxygen pressure of 101/21 kPa and 50/11 kPa respectively. After 40 min at the desired pressure they were injected (99m)Tc-HMPAO and subsequently underwent single photon emission computed tomography. Regional cerebral blood flow distribution changes in the whole brain were assessed by Statistical Parametric Mapping, a well established voxel-based analysis method.

RESULTS

Hypobaric hypoxia increased rCBF distribution in sensorymotor and prefrontal cortices and in central structures. PCO(2) correlated positively and SatO(2) negatively with rCBF in several temporal, parahippocampal, parietal and central structures.

CONCLUSIONS

These findings underscore the specific sensitivity of the frontal lobe to acute hypobaric hypoxia and of limbic and central structures to blood gas changes emphasizing the involvement of these brain areas in acute hypoxia.