An Integrated Multilevel Approach Unveils Complex Seed-Nanoparticle Interactions and Their Implications for Seed Priming

Nanotechnology has the potential to revolutionize agriculture with the introduction of engineered nanomaterials. However, their use is hindered by high cost, marginal knowledge of their interactions with plants, and unpredictable effects related to massive use in crop cultivation. Nanopriming is an innovative seed priming technology able to match economic, agronomic, and environmental needs in agriculture. The present study was focused on unveiling, by a multilevel integrated approach, undisclosed aspects of seed priming mediated by iron oxide magnetic nanoparticles in pepper seeds (Capsicum annuum), one of the most economically important crops worldwide. Inductively coupled plasma atomic emission mass spectrometry and scanning electron microscopy were used to quantify the MNP uptake and assess seed surface changes. Magnetic resonance imaging mapped the distribution of MNPs prevalently in the seed coat. The application of MNPs significantly enhanced the root and vegetative growth of pepper plants, whereas seed priming with equivalent Fe concentrations supplied as FeCl3 did not yield these positive effects. Finally, global gene expression by RNA-sequencing identified more than 2,200 differentially expressed genes, most of them involved in plant developmental processes and defense mechanisms. Collectively, these data provide evidence on the link between structural seed changes and an extensive transcriptional reprogramming, which boosts the plant growth and primes the embryo to cope with environmental challenges that might occur during the subsequent developmental and growth stages.

Counteracting action of Bacillus stratosphericus and Staphylococcus succinus strains against deleterious salt effects on Zea mays L

The salinization of soil is the process of progressive accumulation of salts such as sulfates, sodium, or chlorides into the soil. The increased level of salt has significant effects on glycophyte plants, such as rice, maize, and wheat, which are staple foods for the world's population. Consequently, it is important to develop biotechnologies that improve crops and clean up the soil. Among other remediation methods, there is an environmentally friendly approach to ameliorate the cultivation of glycophyte plants in saline soil, namely, the use of microorganisms tolerant to salt with growth-promoting features. Plant growth-promoting rhizobacteria (PGPR) can improve plant growth by colonizing their roots and playing a vital role in helping plants to establish and grow in nutrient-deficient conditions. Our research aimed to test in vivo halotolerant PGPR, isolated and characterized in vitro in a previous study conducted in our laboratory, inoculating them on maize seedlings to improve their growth in the presence of sodium chloride. The bacterial inoculation was performed using the seed-coating method, and the produced effects were evaluated by morphometric analysis, quantization of ion contents (sodium, potassium), produced biomass, both for epigeal (shoot) and hypogeal (root) organs, and by measuring salt-induced oxidative damage. The results showed an increase in biomass and sodium tolerance and even a reduction of oxidative stress in seedlings pretreated with a PGPR bacterial consortium (Staphylococcus succinus + Bacillus stratosphericus) over the control. Moreover, we observed that salt reduces growth and alters root system traits of maize seedlings, while bacterial treatment improves plant growth and partially restores the root architecture system in saline stress conditions. Therefore, the PGPR seed-coating or seedling treatment could be an effective strategy to enhance sustainable agriculture in saline soils due to the protection of the plants from their inhibitory effect.

Unusual late-fall wildfire in a pre-Alpine Fagus sylvatica forest reduced fine roots in the shallower soil layer and shifted very fine-root growth to deeper soil depth

After an unusual, late-fall wildfire in a European beech (Fagus sylvatica L.) forest in the pre-Alps of northern Italy, the finest roots (0‒0.3 mm diameter) were generally the most responsive to fire, with the effect more pronounced at the shallowest soil depth. While roots 0.3‒1 mm in diameter had their length and biomass at the shallowest soil depth reduced by fire, fire stimulated more length and biomass at the deepest soil depth compared to the control. Fire elevated the total length of dead roots and their biomass immediately and this result persisted through the first spring, after which control and fire-impacted trees had similar fine root turnover. Our results unveiled the fine-root response to fire when subdivided by diameter size and soil depth, adding to the paucity of data concerning fire impacts on beech roots in a natural condition and providing the basis for understanding unusual fire occurrence on root traits. This study suggests that F. sylvatica trees can adapt to wildfire by plastically changing the distribution of fine-root growth, indicating a resilience mechanism to disturbance.

The perils of planning strategies to increase vitamin C content in plants: Beyond the hype

Ever since the identification of vitamin C (ascorbic acid, AsA) as an essential molecule that humans cannot synthesize on their own, finding adequate dietary sources of AsA became a priority in nutrition research. Plants are the main producers of AsA for humans and other non-synthesizing animals. It was immediately clear that some plant species have more AsA than others. Further studies evidenced that AsA content varies in different plant organs, in different developmental stages/environmental conditions and even within different cell compartments. With the progressive discovery of the genes of the main (Smirnoff-Wheeler) and alternative pathways coding for the enzymes involved in AsA biosynthesis in plants, the simple overexpression of those genes appeared a suitable strategy for boosting AsA content in any plant species or organ. Unfortunately, overexpression experiments mostly resulted in limited, if any, AsA increase, apparently due to a tight regulation of the biosynthetic machinery. Attempts to identify regulatory steps in the pathways that could be manipulated to obtain unlimited AsA production were also less successful than expected, confirming the difficulties in "unleashing" AsA synthesis. A different approach to increase AsA content has been the overexpression of genes coding for enzymes catalyzing the recycling of the oxidized forms of vitamin C, namely monodehydroascorbate and dehydroascorbate reductases. Such approach proved mostly effective in making the overexpressors apparently more resistant to some forms of environmental stress, but once more did not solve the issue of producing massive AsA amounts for human diet. However, it should also be considered that a hypothetical unlimited increase in AsA content is likely to interfere with plant development, which is in many ways regulated by AsA availability itself. The present review article aims at summarizing the many attempts made so far to improve AsA production/content in plants, evidencing the most promising ones, and at providing information about the possible unexpected consequences of a pure biotechnological approach not keeping into account the peculiar features of the AsA system in plants.

Fertilization reduces root architecture plasticity in Ulmus pumila used for afforesting Mongolian semi-arid steppe

In this study, we assessed the functional and architectural traits in the coarse roots of Ulmus pumila trees, which are used for afforesting the semi-arid steppe of Mongolia. Tree growth was supported by different watering regimes (no watering, 2, 4, and 8 L h^-1) and by two types of soil fertilization (NPK and compost). In July, 2019, for each of these treatments six trees, outplanted in 2011 as 2-year-old seedlings from a container nursery, were randomly selected, excavated by hand, and digitized. The build-up of root length correlated positively with increasing levels of watering for both soil depths analyzed. The application of fertilizers led to root growth suppression resulting in a general reduction of root length in a lowered rooting depth. When root system characteristics were analyzed in relation to wind direction, unfertilized trees showed higher root diameter values in both soil layers of leeward quadrants, likely a response to mechanical forces to improve stability. On the contrary, fertilized trees did not show differences in root diameter among the different quadrants underscoring a strong reduction in root plasticity with a lack of morpho-architectural response to the mechanical forces generated by the two prevailing winds. Finally, the root branching density, another important trait for fast dissipation of mechanical forces, was significantly reduced by the fertilization, independently of the quadrants and watering regime. Our results suggest that knowledge of the root response to the afforestation techniques applied in the semi-arid steppe of Mongolia is a necessary step for revealing the susceptibility of this forest shelterbelt to the exacerbating environmental conditions caused by climate change and, thus, to the development of a sustainable and successful strategy to restore degraded lands.

Factors associated with treatment escalation among MS specialists and general neurologists: Results from an International cojoint study

BACKGROUND

Previous studies in multiple sclerosis (MS) showed that therapeutic inertia (TI) affects 60-90% of neurologists and up to 25% of daily treatment decisions. The objective of this study was to determine the most common factors and attribute levels associated with decisions to treatment escalation in an international study in MS care.

METHODS

300 neurologists with MS expertise from 20 countries were invited to participate. Participants were presented with 12 pairs of simulated MS patient profiles described by 13 clinically relevant factors. We used disaggregated discrete choice experiments to estimate the weight of factors and attributes affecting physicians' decisions when considering treatment selection. Participants were asked to select the ideal candidate for treatment escalation from modest to higher-efficacy therapies.

RESULTS

Overall, 229 neurologists completed the study (completion rate: 76.3%). The top 3 weighted factors associated with treatment escalation were: previous relapses (20%), baseline expanded disability status scale [EDSS] (18%), and MRI activity (13%). Patient demographics and desire for pregnancy had a modest influence (≤ 3%). We observed differences in the weight of factors associated with treatment escalation between MS specialists and non-MS specialists.

CONCLUSIONS

Our results provide critical information on factors influencing neurologists' treatment decisions and should be applied to continuing medical education strategies.

Morpho-Physiological Responses of Arabidopsis thaliana L. to the LED-Sourced CoeLux® System

The CoeLux^® lighting system reproduces the true effect of natural sunlight entering through an opening in the ceiling, with a realistic sun perceived at an infinite distance surrounded by a clear blue sky. It has already been demonstrated that this new lighting system generates long-term positive effects on human beings; however, there are no investigations so far concerning the plant responses to CoeLux^® lighting. To fill this gap, the model plant Arabidopsis thaliana L. was grown at four different distances from the light source, corresponding to four different light intensities (120, 70, 30, 20 μmol m⁻² s⁻¹). High-pressure sodium lamps were used as control light. Plant phenology and morpho-physiological traits were monitored to assess for the first time the ability of plants to grow and develop under the light spectrum and intensity of the CoeLux^® system. Plants grown at the lower light intensities showed a delayed life cycle and were significantly smaller than plants grown with more light. Furthermore, plants grown under the CoeLux^® light type showed an additional deficit when compared to control plants. Overall, our results show that both the light spectrum and intensity of the CoeLux^® system had a strong impact on A. thaliana growth performance.

Pioneer and fibrous root seasonal dynamics of Vitis vinifera L. are affected by biochar application to a low fertility soil: A rhizobox approach

The present work analyzes the impact of biochar-induced modification of soil physico-chemical properties on intra-annual growth dynamics of pioneer and fibrous grapevine roots. A scanner inserted into a buried rhizobox with a transparent side facing the plant root system was used to acquire images of pioneer and fibrous roots of control and biochar-treated plants throughout the vegetative season. Images were analyzed with ImageJ software to measure root traits. Biochar treatment increased soil pH, nutrient concentration, and water content during the driest and warmest period, while bulk density was reduced. Analysis of both pioneer and fibrous root traits highlighted a single peak of growth during the vegetative season. Pioneer roots were thicker and grew faster than fibrous roots, which were longer and more numerous. Amelioration of physico-chemical properties of biochar-amended soil stimulated an earlier root lengthening, and a higher root number at the onset of the season, which resulted in a greater canopy development compared to control plants. Later, in summer, as a consequence of the higher water content of biochar-treated soil, plants modified their root architecture, lowering the number of fibrous roots probably because of the reduced need to exploit soil for water and nutrient uptake.

Root Biomass Distribution of Populus sibirica and Ulmus pumila Afforestation Stands Is Affected by Watering Regimes and Fertilization in the Mongolian Semi-arid Steppe

Desertification of the semi-arid steppe of Mongolia is advancing very rapidly, motivating afforestation efforts. The "Green Belt" joint project (Government of Mongolia and Republic of Korea), which aims to mitigate soil degradation and develop agroforestry activities through the planting of a forest shelterbelt, is one such response. In these plantations, tree growth has been supported by different watering regimes (no watering, 2, 4, and 8 L h^-1) and by two types of soil fertilization (NPK and Compost). The present paper analyses the effect of these techniques on soil chemistry and root biomass partitioning of Populus sibirica (Horth ex Tausch) and Ulmus pumila (L.) tree species. In July 2019, at the plantation site in Lun Soum, Tuv province (Mongolia), six trees were excavated by hand in each treatment, the root system was divided into taproot and five diameter classes (0-2; 2-5; 5-10; 10-20; > 20 mm), and the biomass was measured. Soil organic matter, macronutrients, and pH were also measured. The addition of fertilizers in the long-term did not enhance the soil chemical properties. The build-up of root biomass in both species correlated positively with increasing levels of the watering, while the application of fertilizers led to root growth suppression. For most of the root classes and both species, an irrigation level of 4 L h^-1 was sufficient to yield the highest biomass and could be recommended for afforesting the semi-arid steppe of Mongolia. The root biomass of P. sibirica was more dependent on the watering regimes and of U. pumila was more negatively influenced by the application of fertilizers, indicating that U. pumila, due to the its lower water need, could be suitable for afforesting semi-arid environments. Our experiments suggest that afforestation practices in the semi-arid steppe of Mongolia should be supported by a prior analysis of plants' needs, soil type, dose, and type of fertilizers to be applied. Knowledge of the root response to the supporting techniques is necessary for choosing the best one for the plantation and, thus, to develop a sustainable and successful strategy to restore these degraded lands.

Reaction Wood Anatomical Traits and Hormonal Profiles in Poplar Bent Stem and Root

Reaction wood (RW) formation is an innate physiological response of woody plants to counteract mechanical constraints in nature, reinforce structure and redirect growth toward the vertical direction. Differences and/or similarities between stem and root response to mechanical constraints remain almost unknown especially in relation to phytohormones distribution and RW characteristics. Thus, Populus nigra stem and root subjected to static non-destructive mid-term bending treatment were analyzed. The distribution of tension and compression forces was firstly modeled along the main bent stem and root axis; then, anatomical features, chemical composition, and a complete auxin and cytokinin metabolite profiles of the stretched convex and compressed concave side of three different bent stem and root sectors were analyzed. The results showed that in bent stems RW was produced on the upper stretched convex side whereas in bent roots it was produced on the lower compressed concave side. Anatomical features and chemical analysis showed that bent stem RW was characterized by a low number of vessel, poor lignification, and high carbohydrate, and thus gelatinous layer in fiber cell wall. Conversely, in bent root, RW was characterized by high vessel number and area, without any significant variation in carbohydrate and lignin content. An antagonistic interaction of auxins and different cytokinin forms/conjugates seems to regulate critical aspects of RW formation/development in stem and root to facilitate upward/downward organ bending. The observed differences between the response stem and root to bending highlight how hormonal signaling is highly organ-dependent.

Anodal transcranial direct current stimulation in chronic migraine and medication overuse headache: A pilot double-blind randomized sham-controlled trial

OBJECTIVES

Little evidence is available on the role of transcranial direct current stimulation (tDCS) in patients affected by chronic migraine (CM) and medication overuse headache (MOH). We aim to investigate the effects of tDCS in patients with CM and MOH as well as its role on brain activity.

METHODS

Twenty patients with CM and MOH were hospitalized for a 7-day detoxification treatment. Upon admission, patients were randomly assigned to anodal tDCS or sham stimulation delivered over the primary motor cortex contralateral to the prevalent migraine pain side every day for 5 days. Clinical data were recorded at baseline (T0), after 1 month (T2) and 6 months (T3). EEG recording was performed at T0, at the end of the tDCS/Sham treatment, and at T2.

RESULTS

At T2 and T3, we found a significant reduction in monthly migraine days (p = 0.001), which were more pronounced in the tDCS group when compared to the sham group (p = 0.016). At T2, we found a significant increase of alpha rhythm in occipital leads, which was significantly higher in tDCS group when compared to sham group.

CONCLUSIONS

tDCS showed adjuvant effects to detoxification in the management of patients with CM and MOH. The EEG recording showed a significant potentiation of alpha rhythm, which may represent a correlate of the underlying changes in cortico-thalamic connections.

SIGNIFICANCE

This study suggests a possible role for tDCS in the treatment of CM and MOH. The observed clinical improvement is coupled with a potentiation of EEG alpha rhythm.

WOX genes expression during the formation of new lateral roots from secondary structures in Populus nigra (L.) taproot

Despite the large amounts of data available on lateral root formation, little is known about their initiation from secondary structures. In the present work, we applied a bending treatment to Populus nigra (L.) woody taproots to induce the formation of new lateral roots. The development of lateral roots was monitored by stereomicroscopic examination of cross-sections. Tissues were sampled from the bending zone in the proximity of the vascular cambium before (time 0) and after the application of bending at three different time points (24, 48, and 72 h) and analyzed for the expression of P. nigra WOX homologs. The initiation of new lateral roots was observed to originate from the vascular cambium zone and was followed by primordium formation and root emergence. PnWOX4a, PnWOX4b, PnWOX5a, PnWOX5b, PnWOX11/12a, and PnWOX11/12b were shown to be expressed during the formation of new lateral roots at different developmental stages. The mechanical stress simulated by bending treatment was shown to activate the molecular mechanism leading to the expression of WOX genes, which are hypothesized to control SLR formation in the cambium zone of poplar taproot.

Functional Traits of Pinus ponderosa Coarse Roots in Response to Slope Conditions

We excavated the root systems of Pinus ponderosa trees growing on a steeply sloped, volcanic ash-influenced soil in the northern Rocky Mountains of the United States to assess their functional coarse-root traits and root system architecture. Trees, outplanted as one-year-old seedlings from a container nursery, were in their 32nd growing season on the site. We found that the trees had deployed more roots, in terms of length and volume, in the downslope and windward quadrants than in their upslope and leeward quadrants, likely a response to mechanical forces toward improving stability. Moreover, we observed the development of three types of root cages (tight, enlarged, and diffused) that likely reflect micro-site characteristics. As the cage type transitioned from tight to enlarged to diffused we measured a decrease in the overall volume of the roots associated with the cage and the taproot becoming a more prominent contributor to the overall volume of the cage. Finally, we noted the development of specialty roots, namely those with I-beam and T-beam shapes in cross section, in the downslope quadrant; these types of roots are known to better counteract compression mechanical forces. These observations improve our understanding of root plasticity and tree rooting response to environmental stimuli, which is becoming an increasingly critical topic as changes in climate increase the frequency and intensity of storms.

Transcription factors PRE3 and WOX11 are involved in the formation of new lateral roots from secondary growth taproot in A. thaliana

The spatial deployment of lateral roots determines the ability of a plant to interact with the surrounding environment for nutrition and anchorage. This paper shows that besides the pericycle, the vascular cambium becomes active in Arabidopsis thaliana taproot at a later stage of development and is also able to form new lateral roots. To demonstrate the above, we implemented a two-step approach in which the first step leads to development of a secondary structure in A. thaliana taproot, and the second applies a mechanical stress on the vascular cambium to initiate formation of a new lateral root primordium. GUS staining showed PRE3, DR5 and WOX11 signals in the cambial zone of the root during new lateral root formation. An advanced level of wood formation, characterized by the presence of medullar rays, was achieved. Preliminary investigations suggest the involvement of auxin and two transcription factors (PRE3/ATBS1/bHLH135/TMO7 and WOX11) in the transition of some vascular cambium initials from a role as producers of xylem/phloem mother cells to founder cells of a new lateral root primordium.

Non-destructive Phenotypic Analysis of Early Stage Tree Seedling Growth Using an Automated Stereovision Imaging Method

A plant phenotyping approach was applied to evaluate growth rate of containerized tree seedlings during the precultivation phase following seed germination. A simple and affordable stereo optical system was used to collect stereoscopic red-green-blue (RGB) images of seedlings at regular intervals of time. Comparative analysis of these images by means of a newly developed software enabled us to calculate (a) the increments of seedlings height and (b) the percentage greenness of seedling leaves. Comparison of these parameters with destructive biomass measurements showed that the height traits can be used to estimate seedling growth for needle-leaved plant species whereas the greenness trait can be used for broad-leaved plant species. Despite the need to adjust for plant type, growth stage and light conditions this new, cheap, rapid, and sustainable phenotyping approach can be used to study large-scale phenome variations due to genome variability and interaction with environmental factors.

Poplar woody taproot under bending stress: the asymmetric response of the convex and concave sides

Background and Aims Progress has been made in understanding the physiological and molecular basis of root response to mechanical stress, especially in the model plant Arabidopsis thaliana, in which bending causes the initiation of lateral root primordia toward the convex side of the bent root. In the case of woody roots, it has been reported that mechanical stress induces an asymmetric distribution of lateral roots and reaction wood formation, but the mechanisms underlying these responses are largely unknown. In the present work, the hypothesis was tested that bending could determine an asymmetric response in the two sides of the main root axis as cells are stretched on the convex side and compressed on the concave side. Methods Woody taproots of 20 seedlings were bent to an angle of 90° using a steel net. Changes in the anatomy, lignin and phytohormone content and proteome expression in the two sides of the bent root were analysed; anatomical changes, including dissimilarities and similarities to those found in poplar bent woody stem, were also considered. Key Results Compression forces at the concave side of poplar root induced the formation of reaction wood which presented a high lignin content and was associated with the induction of cambium cell activity. Auxin seemed to be the main hormone triggering lignin deposition and cell wall strengthening in the concave sides. Abscisic acid appeared to function in the water stress response induced by xylem structures and/or osmotic alterations in the compression sides, whereas gibberellins may control cell elongation and gravitropisms. Conclusions Poplar root reaction wood showed characteristics different from those produced in bent stem. Besides providing biomechanical functions, a bent root ensures water uptake and transport in the deforming condition induced by tension and compression forces by two different strategies: an increase in xylem thickness in the compressed side, and lateral root formation in the tension side.

Interspecific variation in functional traits of oak seedlings (Quercus ilex, Quercus trojana, Quercus virgiliana) grown under artificial drought and fire conditions

To face summer drought and wildfire in Mediterranean-type ecosystems, plants adopt different strategies that involve considerable rearrangements of biomass allocation and physiological activity. This paper analyses morphological and physiological traits in seedlings of three oak species (Quercus ilex, Quercus trojana and Quercus virgiliana) co-occurring under natural conditions. The aim of this study was to evaluate species-specific characteristics and the response of these oak seedlings to drought stress and fire treatment. Seedlings were kept in a growth chamber that mimicked natural environmental conditions. All three species showed a good degree of tolerance to drought and fire treatments. Differences in specific biomass allocation patterns and physiological traits resulted in phenotypic differences between species. In Q. ilex, drought tolerance depended upon adjustment of the allocation pattern. Q. trojana seedlings undergoing mild to severe drought presented a higher photosystem II (PSII) efficiency than control seedlings. Moreover, Q. trojana showed a very large root system, which corresponded to higher soil area exploitation, and bigger leaf midrib vascular bundles than the other two species. Morphological and physiological performances indicated Q. trojana as the most tolerant to drought and fire. These characteristics contribute to a high recruitment potential of Q. trojana seedlings, which might be the reason for the dominance of this species under natural conditions. Drought increase as a result of climate change is expected to favour Q. trojana, leading to an increase in its spatial distribution.

Fine-root carbon and nitrogen concentration of European beech (Fagus sylvatica L.) in Italy Prealps: possible implications of coppice conversion to high forest

Fine-root systems represent a very sensitive plant compartment to environmental changes. Gaining further knowledge about their dynamics would improve soil carbon input understanding. This paper investigates C and N concentrations in fine roots in relation to different stand characteristics resulting from conversion of coppiced forests to high forests. In order to evaluate possible interferences due to different vegetative stages of vegetation, fine-root sampling was repeated six times in each stand during the same 2008 growing season. Fine-root sampling was conducted within three different soil depths (0-10; 10-20; and 20-30 cm). Fine-root traits were measured by means of WinRHIZO software which enable us to separate them into three different diameter classes (0-0.5, 0.5-1.0 and 1.0-2.0 mm). The data collected indicate that N concentration was higher in converted stands than in the coppiced stand whereas C concentration was higher in the coppiced stand than in converted stands. Consequently the fine-root C:N ratio was significantly higher in coppiced than in converted stands and showed an inverse relationship with fine-root turnover rate, confirming a significant change of fine-root status after the conversion of a coppice to high forest.

Fine-root carbon and nitrogen concentration of European beech (Fagus sylvatica L.) in Italy Prealps: possible implications of coppice conversion to high forest

Fine-root systems represent a very sensitive plant compartment to environmental changes. Gaining further knowledge about their dynamics would improve soil carbon input understanding. This paper investigates C and N concentrations in fine roots in relation to different stand characteristics resulting from conversion of coppiced forests to high forests. In order to evaluate possible interferences due to different vegetative stages of vegetation, fine-root sampling was repeated six times in each stand during the same 2008 growing season. Fine-root sampling was conducted within three different soil depths (0-10; 10-20; and 20-30 cm). Fine-root traits were measured by means of WinRHIZO software which enable us to separate them into three different diameter classes (0-0.5, 0.5-1.0 and 1.0-2.0 mm). The data collected indicate that N concentration was higher in converted stands than in the coppiced stand whereas C concentration was higher in the coppiced stand than in converted stands. Consequently the fine-root C:N ratio was significantly higher in coppiced than in converted stands and showed an inverse relationship with fine-root turnover rate, confirming a significant change of fine-root status after the conversion of a coppice to high forest.

Environmental risk factors for REM sleep behavior disorder: a multicenter case-control study

OBJECTIVE

Idiopathic REM sleep behavior disorder is a parasomnia characterized by dream enactment and is commonly a prediagnostic sign of parkinsonism and dementia. Since risk factors have not been defined, we initiated a multicenter case-control study to assess environmental and lifestyle risk factors for REM sleep behavior disorder.

METHODS

Cases were patients with idiopathic REM sleep behavior disorder who were free of dementia and parkinsonism, recruited from 13 International REM Sleep Behavior Disorder Study Group centers. Controls were matched according to age and sex. Potential environmental and lifestyle risk factors were assessed via standardized questionnaire. Unconditional logistic regression adjusting for age, sex, and center was conducted to investigate the environmental factors.

RESULTS

A total of 694 participants (347 patients, 347 controls) were recruited. Among cases, mean age was 67.7 ± 9.6 years and 81.0% were male. Cases were more likely to smoke (ever smokers = 64.0% vs 55.5%, adjusted odds ratio [OR] = 1.43, p = 0.028). Caffeine and alcohol use were not different between cases and controls. Cases were more likely to report previous head injury (19.3% vs 12.7%, OR = 1.59, p = 0.037). Cases had fewer years of formal schooling (11.1 ± 4.4 years vs 12.7 ± 4.3, p < 0.001), and were more likely to report having worked as farmers (19.7% vs 12.5% OR = 1.67, p = 0.022) with borderline increase in welding (17.8% vs 12.1%, OR = 1.53, p = 0.063). Previous occupational pesticide exposure was more prevalent in cases than controls (11.8% vs 6.1%, OR = 2.16, p = 0.008).

CONCLUSIONS

Smoking, head injury, pesticide exposure, and farming are potential risk factors for idiopathic REM sleep behavior disorder.

A sleep continuity scale in Alzheimer's disease: validation and relationship with cognitive and functional deterioration

Considering that disrupted sleep may be detrimental to daytime performance in people with dementia, we set out to construct a questionnaire able to identify sleep patterns potentially associated with clinical and functional disease variables in this population. Two subsets of items indicative of patterns of unstable sleep and of disordered rapid eye movement sleep (REM) were selected. The first included items investigating sleep continuity, with low sleep continuity markers considered indicative of high arousability; the second included items investigating the frequency and quality of dreams and the frequency of clinically identifiable REM sleep behaviour disorder episodes. The questionnaire was administered to 140 outpatients with a diagnosis of mild-to-moderate Alzheimer's disease. The Mini-Mental State Examination (MMSE), Activities of Daily Living (ADL), Instrumental Activities of Daily Living, Neuropsychiatric Inventory and Clinical Dementia Rating (CDR) were administered to quantify cognitive, functional and behavioural impairment. A subscale comprising items investigating sleep discontinuity/fragmentation and showing high internal consistency was constructed and found to correlate significantly with variables considered indexes of cognitive and functional deterioration in AD (MMSE, ADL and CDR). Conversely, it did not prove possible to obtain a subscale of dysfunctional REM phenomena. The use of a rapidly and easily administered sleep scale, like the one we constructed, appears to be suitable for early identification and longitudinal monitoring of sleep disturbances in AD.

Hallucinations and sleep-wake cycle in Alzheimer's disease: a questionnaire-based study in 218 patients

The aim was to evaluate the relationship between hallucinations and the sleep-wake cycle in a sample of Alzheimer's disease (AD) patients in the early-moderate stage. Two hundred and eighteen AD patients (66 males, 152 females, mean age 74.3+/-6.85) were administered a sleep questionnaire in the presence of a care-giver. Twenty-six out of 218 (12%) reported the occurrence of hallucinations, mainly visual. In 18/28 (69%) hallucinations occurred when the patient was awake and in 8 (31%) hallucinations were reported to occur close to a specific phase of the sleep-wake cycle. Vivid dreams were reported in 25/218 (11%) and violent sleep-related and dream-related behaviours (probable REM behaviour episodes) in 22/218 (10%). Both REM phenomena were more frequent in AD hallucinators than in AD non-hallucinators (26.9% vs. 9.3%, and 26.9% vs. 7.8%, p<0.007). Our data indicate a lower incidence of hallucinations and presumable REM behaviour disorder (RBD) in AD, at least in the early-moderate phase, than that observed in synucleinopathies. However, the higher occurrence of vivid dreams and RBD in AD patients with hallucinations compared to those without hallucinations indicates a potential role of disordered REM sleep in influencing the occurrence of hallucinations in AD, similar to what has been observed in synucleinopathies.

Sleep disorders in Parkinson's disease: facts and new perspectives

Awareness of the clinical and pathophysiological importance of sleep disorders in Parkinson's disease (PD) has been growing in recent years. Sleep disorders are now regarded as important among non-motor symptoms in PD and as a significant variable of PD-related quality of life. Furthermore, some sleep disorders, namely REM behaviour disorder (RBD), has been hypothesised to herald PD by years. Subjective reports of disrupted nocturnal sleep and daytime sleepiness appear to be supported by descriptions of several sleep alterations at nocturnal polysomnographic investigation and Multiple Sleep Latency Test findings. Sleep alterations in PD are to be viewed from the multifactorial perspective of a framework of reciprocally interacting factors: pathophysiology of the disease itself, sleep-related motor symptoms, dopaminergic treatments, ageing, depression, restless legs, periodic limb movements (PMLs) and sleep-disordered breathing. Ad hoc questionnaires and scales such as the Parkinson's Disease Sleep Scale and the Short and Practical (SCOPA) Sleep Scale are now available for the evaluation of disordered sleep in PD patients and have been proved to be useful for preliminary screening of sleep disorders in PD. However in a few cases a video-polysomnography (V-PSG) is needed in order to confirm a diagnosis of sleep disorder in PD, particularly in diagnosing RBD. As for treatment of sleep disorders, combined pharmacological and non-pharmacological protocols appear to be particularly suitable in their treatment in PD.

Non-convulsive status epilepticus and generalised tonic–clonic seizures ersisting in old age in a patient with idiopathic generalised epilepsy: a long-term observation

Persisting non-convulsive status epilepticus in a man with idiopathic generalised epilepsy is reported. After a first generalised tonic/clonic seizure on awakening one day at the age of 20, the patient experienced rare non-convulsive status epilepticus until the age of 73, when the frequency of the episodes increased, in spite of the initiation of treatment with antiepileptic drugs. No significant cognitive decline was documented when the patient was 83. The existence of such conditions in the context of idiopathic generalised epilepsy shows the problems of syndromic diagnosis and of age dependency of some epileptic phenomena over the course of life with potential bidirectional influences between epileptic manifestations and senile processes.

Intracerebral recordings of minor motor events, paroxysmal arousals and major seizures in nocturnal frontal lobe epilepsy

The clinical features of nocturnal frontal lobe epilepsy (NFLE) consist of a spectrum of paroxysmal motor manifestations ranging from minor motor events (MMEs) to paroxysmal arousals (PAs) and major seizures. During MMEs and PAs scalp EEG generally does not show definite ictal abnormalities. We describe the clinical and electrophysiological features of three patients affected by drug-resistant NFLE studied with intracerebral electrodes during a presurgical evaluation. The stereo-EEG (SEEG) investigation revealed that MMEs can be fragments of the major seizure and occur during a brief epileptic discharge or on the following arousal. PAs, in the same subject, do not show a definite stereotypy despite the morphological and topographic similarity of the epileptic discharges, thus indicating that other variables may influence the clinical features of PAs.

Rhythmic movements during sleep: a physiological and pathological profile

Rhythmic movement disorder (RMD) consists of rhythmic movements (RMs) that occur on falling asleep or during sleep, can involve any part of the body and have a reported frequency ranging from 0.5 to 2 Hz. RMs have been reported to occur in a high proportion of normal children as a self-limiting phenomenon starting and remitting within early infancy. However, there have also been descriptions of forms of RMD occurring against a background of mental retardation or persisting beyond childhood, or having onset in adulthood. So, the occurrence of RMs can be regarded as both a physiological and a pathological phenomenon. The few polysomnographic studies conducted in this field have shown that, in some forms of RMD, RMs are highly linked to arousal fluctuations. However, the mechanisms that underlie the genesis of RMs and are capable of leading to both physiological and pathological patterns of RMs are not fully understood. Here we emphasise the possibility that the central motor pattern generator, recently hypothesised to play a role in the genesis of motor phenomena during sleep in the cases of parasomnia and epileptic seizures, might account for the occurrence of RMs in both physiological and pathological conditions.

Hypnic headache

Hypnic headache (HH) occurs exclusively during sleep. Six attacks were recorded during nocturnal polysomnographic (PSG) monitoring of 10 HH patients. The PSG data obtained indicate that the attacks arose directly from sleep: four from non-REM and two from REM sleep. In no patient were the HH attacks found to show any close temporal relationship with sleep-related breathing abnormalities.

Sleep attacks in Parkinson's disease: a clinical and polysomnographic study

The objective of the study was to evaluate daytime sleepiness, (the features of episodes of sudden sleep onset), i. e., so-called sleep attacks (SAs), in three male Parkinson's disease (PD) patients (mean age 66 years) on chronic therapy with ropirinole or pramipexole. A structured clinical interview, the Epworth Sleepiness Scale, and continuous 24-h ambulatory polysomnography were used to assess the features of SAs occurring in the patients in their normal home environments. The polysomnographic patterns characterizing SAs (sleep occurring against a background of wakefulness, and not preceded by a feeling of sleepiness or by other heralding symptoms) were analyzed. The results showed that SAs can be clearly documented through polysomnographic monitoring and really, but rarely, occur in PD. SAs seem to represent the extreme of the continuum of daytime sleepiness observed in PD patients.

Hallucinations and sleep-wake cycle in PD: a 24-hour continuous polysomnographic study

Twenty-four-hour ambulatory polysomnography was performed in 20 patients with PD who were having visual hallucinations (12 men and 8 women, mean age 70 +/- 6 years). Visual hallucinations were clearly related to daytime NREM sleep or nocturnal REM sleep in 33% of the instances. The data reinforce the hypothesis that neural mechanisms implicated in generating sleep and, in particular, in dream imagery play a role in the occurrence of visual hallucinations in PD.

Heterotopic tracheal transplants: techniques and applications

Heterotopic tracheal transplants, placed subcutaneously in syngeneic rats have been extensively used in our laboratory. The objective of these experiments was to study the toxic and/or carcinogenic effect of several compounds on the respiratory tract mucosa. This was attained by exposing the transplants to an intraluminal pettet containing the toxicant or carcinogen mixed with an adequate matrix (gelatin, beeswax, stearyl alcohol, silastic, etc.). By varying the concentration of the test chemicals, it is possible to study dose-response relationships, and by changing the pellet matrix, the effects of release rate (dose rate) can be analyzed. Several end points can be studied, such as histological changes in the mucociliary epithelium, changes in mucus secretion, tumor induction and changes in the in vitro behavior of the epithelial cells after in vivo exposure. In addition, by de-epithelializing the tracheal transplants and reseeding them with another cell population, e.g., from previously treated cell cultures or from human specimens and transplanting them subcutaneously in nude mice, completely new vistas on the effect of chemicals can be opened.

Propagation of normal human epithelial cell populations using an in vivo culture system. Description and applications

A new model using xenotransplanted human epithelia was developed for the study of toxic and carcinogenic effects of chemicals. Epithelial cells from the respiratory tract of 4 male and 3 female premature and fullterm fetuses were enzymatically removed and inoculated into deepithelialized rat tracheas. These were sealed at both ends and transplanted subcutaneously into nude mice. After 3-4 weeks, a normal mucociliary epithelium covered the tracheal lumen. At this stage the epithelial cells could be isolated again and transplanted into new denuded rat tracheas. This passaging could be repeated up to six times, each permitting an amplification factor of approximately 3. Tracheal transplants containing cells of human origin (in vivo Passages 2-4) were treated with 7,12-dimethylbenz(a)anthracene. Hyperplasias, squamous metaplasias, and dysplasias were seen 1-8 weeks after initiation of treatment, indicating that the responses of human and rodent epithelial cells to polycyclic aromatic hydrocarbons are similar. Initial experiments with skin and esophageal epithelia suggest that other covering epithelia could also be used in this fashion for evaluation of toxicants and carcinogens that are likely to come into contact with these tissues.

Epithelial focus assay for early detection of carcinogen-altered cells in various organs of rats exposed in situ to N-nitrosoheptamethyleneimine

The purpose of these studies was to determine a) whether epithelial cells with altered in vitro growth capacity occur not only after topical application of 7-12-dimethylbenz [a]-anthracene but also after systemic administration of a carcinogenic nitrosamine, and b) whether such cells can be isolated from tissues other than tracheal mucosa. AT 3 and 20 weeks following intragastric administration of 150, 300, or 600 mg N-nitrosohepatamethyleneimine (NHMI)/kg, cells were harvested from tracheas, esophagi, and lungs (target tissues for NHMI) of inbred F344 rats and seeded into culture dishes. Normal cells from nonexposed organs produced no proliferative epithelial foci (EF). Of those tracheas sampled 3 weeks following exposure to 150 and 300 mg/kg 10 and 20%, respectively, contained one or more EF that could be subcultured. Of these tracheas harvested 3 weeks post exposure to 600 mg/kg or 20 weeks post exposure to 150-600 mg/kg, 80-100% contained EF that could be subcultured. Twenty weeks after 600 mg NHMI/kg, the incidence of tracheas harboring cell populations with neoplastic potential (agarose-positive EF) was 80%, whereas the tracheal tumor incidence determined at 24 months was only 29%. Epithelial focus-forming units with various abnormal in vitro growth potentials were also detected in esophagi and lungs of NHMI-exposed rats.

Studies of neoplastic development in respiratory tract epithelium

The dynamics of neoplastic development in conducting airways were studied in an animal model using morphologic and tissue culture techniques. Evidence for the regression of many metaplastic-dysplastic lesions, including advanced "preneoplastic" lesions, was provided. This regression of lesions is not synonymous with reversion of the neoplastic process. The number of "carcinogen-altered" cells and the number of cells with neoplastic potential continued to increase as a function of time after carcinogen exposure. With the cell culture methods developed for these studies, it is possible to analyze qualitatively and quantitatively the progression of the neoplastic process as it takes place in vivo and to detect and enumerate the progenitor cells of later-appearing cancers. The investigations also provide strong evidence suggesting that carcinogen-exposed organs contain many more cells with neoplastic potential. This expression may, however, be sharply enhanced when permissive or promoting conditions prevail. The investigations open up new avenues to develop means for detection of preneoplastic cell populations and for therapeutic intervention during early phases of the neoplastic disease process.

Differentiation of normal and cultured preneoplastic tracheal epithelial cells in rats: importance of epithelial mesenchymal interactions

Changes in the dependence on mesenchymal tissues for survival and differentiation in inbred F344 female rats were investigated in tracheal epithelial cells exposed to 7, 12-dimethylbenz[a]anthracene (DMBA) and 12-O-tetradecanoylphorbol 13-acetate (TPA). Fresh suspensions of normal tracheal epithelium or cultured preneoplastic cells were inoculated into isolated organ segments (trachea, esophagus, bladder, or small intestine) or into Dacron containers that were then implanted subdermally into isogenic recipients. At various times after cell inoculation and implantation, tissues were removed for histologic evaluation. Normal cells inoculated into frozen-thawed trachea, esophagus, bladder, and intestine yielded a regular mucociliary epithelium. Normal cell inocula did not, however, survive in tracheae previously heated (100 degrees C), fixed in ethanol, or digested with collagenase; nor did normal cells survive in Dacron containers unless tracheal fibroblasts plus epithelial cells were inoculated together. DMBA- and TPA-exposed cell populations with increased growth capacity in vitro survived and differentiated on all of the above substrates. Our observations were consistent with those of other investigators in that normal cell survival and differentiation depend to some extent on interaction with extracellular material(s) present in various organs. The essential elements were not supplied by subdermal fibroblasts alone. For survival and differentiation in vivo, preneoplastic cells appeared to have less stringent substrate requirements than did normal cells. Application of the described techniques to the study of changes occurring early in the development of neoplastic disease is discussed.