Search results for: Efstratios Psarianos

Authors: Christos Chatzissavvidis, Christina Topali, Chrysovalantou Antonopoulou, Vasileios Takavakoglou, Efstratios Psarianos, Eleanna Pana, Dimitrios Karpouzos, Pantazis Georgiou

Abstract:

Olive (Olea europaea L.) culture in the Mediterranean basin faces significant challenges due to climate change, soil degradation, and the decline in biodiversity as a result of using agrochemicals. The effects of climate change are particularly severe because of the intense competition among plants for natural resources such as land, water, and available nutrients. Climate change, manifested through extreme weather events, drought periods, and high temperatures, directly affects the biological cycle of olive trees. As a result, critical processes such as bud differentiation, flowering, fruit set, and alternate bearing are adversely impacted. Consequently, in combination with other factors, the phenomenon of fruitlessness is increasingly observed in olive orchards of several regions. Addressing these challenges necessitates innovative and sustainable agricultural practices, among which biostimulants have emerged as a promising solution. Biostimulants, comprising natural substances or microorganisms, enhance plant growth, resilience, and productivity. Moreover, they promote root development, increase soil water retention, and boost microbial activity, thereby improving nutrient availability for plants. Acting as signal messengers such as phytohormones, biostimulants strengthen plants’ tolerance to abiotic stresses. Furthermore, their application has been shown to improve the qualitative characteristics of olive oil, making them an appealing alternative for sustainable farming practices. This study investigates the effect of biostimulant formulations on the vegetative growth, flowering and fruit set of olive (cv. Kolovi) trees, on the island of Lesvos, Greece. Six categories of biostimulants (algae extracts, amino acids, humic acids, glycinebetaine, microorganisms, and plant growth regulators) were applied foliarly once in two olive orchards, one with pruned and the other with unpruned trees. The preliminary results of the first application period in May 2024 revealed that treatments with humic acids and algae extracts significantly improved vegetative growth in both orchards. Humic acid-treated trees presented the highest new shoot length, while algae extract-treated trees exhibited the greatest number of new leaves in the pruned orchard. Regarding reproductive development, the application of glycine-betaine led to the highest fruit setting in the unpruned orchard, while amino acid and microorganism treatments gave consistently the highest numbers of flowers in both orchards, compared to other treatments. All biostimulants treatments presented consistently highest values in all tested parameters, as compared to control, highlighting the positive impact of these products on olive tree performance. These initial research findings underscore the potential use of biostimulants, particularly humic acids, algae extracts, and glycine-betaine, as sustainable alternatives to conventional farming practices. Their ability to enhance vegetative growth, flowering, and fruit set offers a promising pathway to improving olive tree resilience and productivity amidst ongoing environmental challenges. This research is implemented by the Operational Group OLIVEUP (Μ16SΥΝ2-00066), and co-funded by European Union and Greece under the RDP 2014-2020

Keywords: climate change, plant physiology, resilience, stress, sustainable practices

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Authors: Efstratios Karavasilis, Foteini Christidi, Georgios Velonakis, Agapi Plousi, Kalliopi Platoni, Nikolaos Kelekis, Ioannis Evdokimidis, Efstathios Efstathopoulos

Abstract:

Introduction: Advanced structural and functional neuroimaging techniques contribute to the study of anatomical and functional brain connectivity and its role in the pathophysiology and symptoms’ heterogeneity in several neurodegenerative disorders, including multiple sclerosis (MS). Aim: In the present study, we applied multiparametric neuroimaging techniques to investigate the structural and functional cortico-cerebellar changes in MS patients. Material: We included 51 MS patients (28 with clinically isolated syndrome [CIS], 31 with relapsing-remitting MS [RRMS]) and 51 age- and gender-matched healthy controls (HC) who underwent MRI in a 3.0T MRI scanner. Methodology: The acquisition protocol included high-resolution 3D T1 weighted, diffusion-weighted imaging and echo planar imaging sequences for the analysis of volumetric, tractography and functional resting state data, respectively. We performed between-group comparisons (CIS, RRMS, HC) using CAT12 and CONN16 MATLAB toolboxes for the analysis of volumetric (cerebellar gray matter density) and functional (cortico-cerebellar resting-state functional connectivity) data, respectively. Brainance suite was used for the analysis of tractography data (cortico-cerebellar white matter integrity; fractional anisotropy [FA]; axial and radial diffusivity [AD; RD]) to reconstruct the cerebellum tracts. Results: Patients with CIS did not show significant gray matter (GM) density differences compared with HC. However, they showed decreased FA and increased diffusivity measures in cortico-cerebellar tracts, and increased cortico-cerebellar functional connectivity. Patients with RRMS showed decreased GM density in cerebellar regions, decreased FA and increased diffusivity measures in cortico-cerebellar WM tracts, as well as a pattern of increased and mostly decreased functional cortico-cerebellar connectivity compared to HC. The comparison between CIS and RRMS patients revealed significant GM density difference, reduced FA and increased diffusivity measures in WM cortico-cerebellar tracts and increased/decreased functional connectivity. The identification of decreased WM integrity and increased functional cortico-cerebellar connectivity without GM changes in CIS and the pattern of decreased GM density decreased WM integrity and mostly decreased functional connectivity in RRMS patients emphasizes the role of compensatory mechanisms in early disease stages and the disintegration of structural and functional networks with disease progression. Conclusions: In conclusion, our study highlights the added value of multimodal neuroimaging techniques for the in vivo investigation of cortico-cerebellar brain changes in neurodegenerative disorders. An extension and future opportunity to leverage multimodal neuroimaging data inevitably remain the integration of such data in the recently-applied mathematical approaches of machine learning algorithms to more accurately classify and predict patients’ disease course.

Keywords: advanced neuroimaging techniques, cerebellum, MRI, multiple sclerosis

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