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1.
Materials (Basel) ; 17(10)2024 May 11.
Article in English | MEDLINE | ID: mdl-38793342

ABSTRACT

This study presents a novel approach for improving the interfacial adhesion between Nd-Fe-B spherical magnetic powders and polyamide 12 (PA12) in polymer-bonded magnets using plasma treatments. By applying radio frequency plasma to the magnetic powder and low-pressure microwave plasma to PA12, we achieved a notable enhancement in the mechanical and environmental stability of fused deposition modeling (FDM)-printed Nd-Fe-B/PA12 magnets. The densities of the FDM-printed materials ranged from 92% to 94% of their theoretical values, with magnetic remanence (Br) ranging from 85% to 89% of the theoretical values across all batches. The dual plasma-treated batch demonstrated an optimal mechanical profile with an elastic modulus of 578 MPa and the highest ductility at 21%, along with a tensile strength range of 6 to 7 MPa across all batches. Flexural testing indicated that this batch also achieved the highest flexural strength of 15 MPa with a strain of 5%. Environmental stability assessments confirmed that applied plasma treatments did not compromise resistance to corrosion, evidenced by negligible flux loss in both hygrothermal and bulk corrosion tests. These results highlight plasma treatment's potential to enhance mechanical strength, magnetic performance, and environmental stability.

2.
Heliyon ; 10(4): e26024, 2024 Feb 29.
Article in English | MEDLINE | ID: mdl-38420464

ABSTRACT

This research focuses on the surface modification of Nd-Fe-B magnetic powder to enhance its thermal and oxidation resistance without compromising magnetic properties and to improve adhesion to the polymer binder for enhanced mechanical properties. A three-step surface modification process involving phosphatization treatment, tetraethyl orthosilicate (TEOS) application, and 3-aminopropyltriethoxysilane (APTES) grafting, was applied to the powder, which was then compounded with polyamide 12 and injection-moulded into cylinders and dog-bone-shaped tubes. The resulting magnets exhibited remanence (Br) of 487.6 mT, coercivity (Hci) of 727.7 kA/m, and energy product (BHmax) of 39.3 kJ/m3. The modified magnets demonstrated exceptional corrosion resistance and thermal stability, with less than 5% irreversible flux loss after exposure to hot water, temperature shock, and pressurised steam. Furthermore, the modified magnets displayed significantly higher tensile strength, elongation at break, and elastic modulus with improvements of 62%, 16.7%, and 19.9%, respectively, compared to the non-modified batch. Additionally, the modified batch showed a notable 52% increase in flexural stress during flexural testing. These findings underscore the potential of silane surface modifications in producing injection-moulded permanent magnets based on Nd-Fe-B alloy, extending their shelf life and enhancing their overall performance.

4.
Materials (Basel) ; 16(8)2023 Apr 10.
Article in English | MEDLINE | ID: mdl-37109829

ABSTRACT

In this research, the feasibility of additive manufacturing of permanent bonded magnets using fused deposition modelling (FDM) technology was investigated. The study employed polyamide 12 (PA12) as the polymer matrix and melt-spun and gas-atomized Nd-Fe-B powders as magnetic fillers. The effect of the magnetic particle shape and the filler fraction on the magnetic properties and environmental stability of polymer-bonded magnets (PBMs) was investigated. It was found that filaments for FDM made with gas-atomized magnetic particles were easier to print due to their superior flowability. As a result, the printed samples exhibited higher density and lower porosity when compared to those made with melt-spun powders. Magnets with gas-atomized powders and a filler loading of 93 wt.% showed a remanence (Br) of 426 mT, coercivity (Hci) of 721 kA/m, and energy product (BHmax) of 29 kJ/m3, while melt-spun magnets with the same filler loading had a remanence of 456 mT, coercivity of 713 kA/m, and energy product of 35 kJ/m3. The study further demonstrated the exceptional corrosion resistance and thermal stability of FDM-printed magnets, with less than 5% irreversible flux loss when exposed to hot water or air at 85 °C for over 1000 h. These findings highlight the potential of FDM printing for producing high-performance magnets and the versatility of this manufacturing method for various applications.

5.
Plants (Basel) ; 9(10)2020 Oct 06.
Article in English | MEDLINE | ID: mdl-33036218

ABSTRACT

(1) Background: Verticillium wilt (VW) of hop is a devastating disease caused by the soil-borne fungi Verticillium nonalfalfae and Verticillium dahliae. As suggested by quantitative trait locus (QTL) mapping and RNA-Seq analyses, the underlying molecular mechanisms of resistance in hop are complex, consisting of preformed and induced defense responses, including the synthesis of various phenolic compounds. (2) Methods: We determined the total polyphenolic content at two phenological stages in roots and stems of 14 hop varieties differing in VW resistance, examined the changes in the total polyphenols of VW resistant variety Wye Target (WT) and susceptible Celeia (CE) on infection with V. nonalfalfae, and assessed the antifungal activity of six commercial phenolic compounds and total polyphenolic extracts from roots and stems of VW resistant WT and susceptible CE on the growth of two different V. nonalfalfae hop pathotypes. (3) Results: Generally, total polyphenols were higher in roots than stems and increased with maturation of the hop. Before flowering, the majority of VW resistant varieties had a significantly higher content of total polyphenols in stems than susceptible varieties. At the symptomatic stage of VW disease, total polyphenols decreased in VW resistant WT and susceptible CE plants in both roots and stems. The antifungal activity of total polyphenolic extracts against V. nonalfalfae was higher in hop extracts from stems than those from roots. Among the tested phenolic compounds, only p-coumaric acid and tyrosol markedly restricted fungal growth. (4) Conclusions: Although the correlation between VW resistance and total polyphenols content is not straightforward, higher levels of total polyphenols in the stems of the majority of VW resistant hop varieties at early phenological stages probably contribute to fast and efficient activation of signaling pathways, leading to successful defense against V. nonalfalfae infection.

6.
Front Pharmacol ; 11: 357, 2020.
Article in English | MEDLINE | ID: mdl-32273845

ABSTRACT

INTRODUCTION: While medicine shortages are complex, their mitigation is more of a challenge. Prospective risk assessment as a means to mitigate possible shortages, has yet to be applied equally across healthcare settings. The aims of this study have been to: 1) gain insight into risk-prevention against possible medicine shortages among healthcare experts; 2) review existing strategies for minimizing patient-health risks through applied risk assessment; and 3) learn from experiences related to application in practice. METHODOLOGY: A semi-structured questionnaire focusing on medicine shortages was distributed electronically to members of the European Cooperation in Science and Technology (COST) Action 15105 (28 member countries) and to hospital pharmacists of the European Association of Hospital Pharmacists (EAHP) (including associated healthcare professionals). Their answers were subjected to both qualitative and quantitative analysis (Microsoft Office Excel 2010 and IBM SPSS Statistics®) with descriptive statistics based on the distribution of responses. Their proportional difference was tested by the chi-square test and Fisher's exact test for independence. Differences in the observed ordinal variables were tested by the Mann-Whitney or Kruskal-Wallis test. The qualitative data were tabulated and recombined with the quantitative data to observe, uncover and interpret meanings and patterns. RESULTS: The participants (61.7%) are aware of the use of risk assessment procedures as a coping strategy for medicine shortages, and named the particular risk assessment procedure they are familiar with failure mode and effect analysis (FMEA) (26.4%), root cause analysis (RCA) (23.5%), the healthcare FMEA (HFMEA) (14.7%), and the hazard analysis and critical control point (HACCP) (14.7%). Only 29.4% report risk assessment as integrated into mitigation strategy protocols. Risk assessment is typically conducted within multidisciplinary teams (35.3%). Whereas 14.7% participants were aware of legislation stipulating risk assessment implementation in shortages, 88.2% claimed not to have reported their findings to their respective official institutions. 85.3% consider risk assessment a useful mitigation strategy. CONCLUSION: The study indicates a lack of systematically organized tools used to prospectively analyze clinical as well as operationalized risk stemming from medicine shortages in healthcare. There is also a lack of legal instruments and sufficient data confirming the necessity and usefulness of risk assessment in mitigating medicine shortages in Europe.

7.
Acta Pharm ; 70(2): 249-257, 2020 Jun 01.
Article in English | MEDLINE | ID: mdl-31955142

ABSTRACT

Self-medication of children by their parents (SMCP) is an important public health issue as the effects and potential risks may be unpredictable. The objective of this first national Montenegrin study was to assess the prevalence of and factors influencing SMCP among schoolchildren. Data were obtained from a national representative sample of 4496 schoolchildren aged 7-13 years (50.4 % boys). Parents/caregivers completed a questionnaire concerning their demographic characteristics, socio-economic and cultural status, as well as the self-medication (SM) of their children. The association between SMCP and parents' socio-economic, demographic or cultural status was assessed by logistic regression analyses. The prevalence rate of SMCP was 24.6 %. Univariate logistic regression showed that maternal socio-demographic characteristics (educational level, employment status, health care profession and smoking habits) were relevant for SMCP. In a multiple logistic regression the independent effect /adjusted odds ratio (AOR) (95 % CI)/of maternal factors on SMCP remained for: education /2.23 (1.18-4.24)/, university-level vs. no education; profession /1.50 (1.07-3.00)/, health profession vs. non-health profession; and smoking habit /1.22 (1.04-1.42)/smokers vs. non-smokers. SMCP may be expected for every fourth child in Montenegro. Specific maternal factors that independently raise the probability of SMCP are higher education, health profession and smoking.


Subject(s)
Cigarette Smoking/adverse effects , Health Occupations/statistics & numerical data , Self Medication/statistics & numerical data , Adolescent , Child , Cross-Sectional Studies , Female , Humans , Logistic Models , Male , Parents , Surveys and Questionnaires
8.
Rev. int. androl. (Internet) ; 17(1): 8-14, ene.-mar. 2019. tab
Article in English | IBECS | ID: ibc-182209

ABSTRACT

Objective: Extract of Pygeum africanum (PAE) is commonly used herbal medication in the treatment of benign prostatic hyperplasia. In Montenegro and neighboring countries, PAE is primarily advertised as dietary supplement in the treatment of erectile dysfunction. The purpose of this study was to broaden the current cognition concerning its safety profile. Material and methods: Twenty-four adult male Wistar rats were used. The first control group (O) received water and second control group (OO) received olive oil for 30 days. The third and fourth groups (PA5 and PA10) were treated with PAE dissolved in olive oil (50 and 100mg/kg p.o. daily). The behavior of animals was observed continuously, bodyweight gain (BWG) was calculated weekly and the weight of selected organs was measured at the end of experiment. Total protein and glutathione content of the liver were analyzed. Standard biochemical analyses were also performed. Results: BWG was higher in PA5 compared to both controls at all measuring intervals. Liver weight/body weight ratio was significantly higher in PA10 in comparison with O. Prostate weight/body weight ratio was lower in both PA5 and PA10 compared to OO, achieving statistical significance in PA5. The value of creatinine was higher in PA5 and PA10 compared to both control groups, but achieving statistical significance in PA10 only. LDH was also increased in PA5 and PA10 compared to both controls. Conclusions: Both dosage regimens of PAE, particularly PA10, caused some toxicological effects in Wistar rats after one month of application. Kidney, skeletal muscle and/or myocardium are suspected as target sites of PA toxicity most likely. In order to provide more reliable conclusion it is necessary to conduct an additional research on the basis of these findings


Objetivo: El extracto de Pygeum africanum (PAE) es un producto de origen vegetal que frecuentemente se utiliza en el tratamiento de la hiperplasia benigna de próstata. En Montenegro y en los países limítrofes, el PAE se anuncia principalmente como suplemento dietético en el tratamiento de la disfunción eréctil. El propósito de este estudio fue ampliar el conocimiento actual respecto a su perfil de seguridad. Material y métodos: Se utilizaron 24 ratas macho adultas de raza Wistar. El primer grupo de control (O) recibió agua y el segundo grupo de control (OO) recibió aceite de oliva durante 30 días. El tercer y cuarto grupos (PA5 y PA10) se trataron con PAE disuelto en aceite de oliva (50 y 100mg/kg vo diariamente). Se observó continuamente el comportamiento de los animales, semanalmente se calculó el incremento del peso corporal (IPC), y el peso de los órganos seleccionados se midió al final del experimento. Se analizaron el contenido total de proteína y glutatión del hígado. También se realizaron análisis bioquímicos habituales. Resultados: El IPC fue mayor en PA5 que en los 2 grupos control en todos los intervalos de medición. La relación entre peso del hígado y peso corporal fue considerablemente mayor en PA10 que en O. La relación entre peso de la próstata y peso corporal de la próstata fue menor tanto en PA5 como en PA10 en comparación con OO, por lo que se obtuvo significación estadística en PA5. El valor de la creatinina fue más elevado en PA5 y PA10 en comparación con ambos grupos de control, pero alcanzó significación estadística solo en PA10. La LDH también se incrementó en PA5 y PA10 en comparación con los 2 grupos control. Conclusiones: Las 2 pautas de dosificación de PAE, sobre todo en PA10, provocaron algunos efectos toxicológicos en ratas de raza Wistar después de un mes de aplicación. Se sospecha que muy probablemente el riñón, el musculoesquelético o el miocardio sean lugares diana de los efectos tóxicos de PAE. Para ofrecer una conclusión más fiable, es necesario llevar a cabo más investigación sobre la base de estos hallazgos


Subject(s)
Animals , Rats , Plant Extracts/pharmacokinetics , Prostatic Hyperplasia/drug therapy , Prunus africana/toxicity , Musculoskeletal System/drug effects , Heart/drug effects , Disease Models, Animal , Case-Control Studies
9.
Rev Int Androl ; 17(1): 8-14, 2019.
Article in English | MEDLINE | ID: mdl-30691591

ABSTRACT

OBJECTIVE: Extract of Pygeum africanum (PAE) is commonly used herbal medication in the treatment of benign prostatic hyperplasia. In Montenegro and neighboring countries, PAE is primarily advertised as dietary supplement in the treatment of erectile dysfunction. The purpose of this study was to broaden the current cognition concerning its safety profile. MATERIAL AND METHODS: Twenty-four adult male Wistar rats were used. The first control group (O) received water and second control group (OO) received olive oil for 30 days. The third and fourth groups (PA5 and PA10) were treated with PAE dissolved in olive oil (50 and 100mg/kg p.o. daily). The behavior of animals was observed continuously, bodyweight gain (BWG) was calculated weekly and the weight of selected organs was measured at the end of experiment. Total protein and glutathione content of the liver were analyzed. Standard biochemical analyses were also performed. RESULTS: BWG was higher in PA5 compared to both controls at all measuring intervals. Liver weight/body weight ratio was significantly higher in PA10 in comparison with O. Prostate weight/body weight ratio was lower in both PA5 and PA10 compared to OO, achieving statistical significance in PA5. The value of creatinine was higher in PA5 and PA10 compared to both control groups, but achieving statistical significance in PA10 only. LDH was also increased in PA5 and PA10 compared to both controls. CONCLUSIONS: Both dosage regimens of PAE, particularly PA10, caused some toxicological effects in Wistar rats after one month of application. Kidney, skeletal muscle and/or myocardium are suspected as target sites of PA toxicity most likely. In order to provide more reliable conclusion it is necessary to conduct an additional research on the basis of these findings.


Subject(s)
Plant Extracts/toxicity , Prunus africana/chemistry , Animals , Cardiotoxicity/etiology , Disease Models, Animal , Dose-Response Relationship, Drug , Kidney/drug effects , Kidney/pathology , Male , Muscle, Skeletal/drug effects , Muscle, Skeletal/pathology , Plant Extracts/administration & dosage , Rats , Rats, Wistar
10.
Sci Rep ; 7(1): 1244, 2017 04 28.
Article in English | MEDLINE | ID: mdl-28455517

ABSTRACT

Imitation and observation of actions and facial emotional expressions activates the human fronto-parietal mirror network. There is skepticism regarding the role of this low-level network in more complex high-level social behaviour. We sought to test whether neural activation during an observation/imitation task was related to both lower and higher level social cognition. We employed an established observe/imitate task of emotional faces during functional MRI in 28 healthy adults, with final analyses based on 20 individuals following extensive quality control. Partial least squares (PLS) identified patterns of relationships between spatial activation and a battery of objective out-of-scanner assessments that index lower and higher-level social cognitive performance, including the Penn emotion recognition task, reading the mind in the eyes, the awareness of social inference test (TASIT) parts 1, 2, and 3, and the relationships across domains (RAD) test. Strikingly, activity in limbic, right inferior frontal, and inferior parietal areas during imitation of emotional faces correlated with performance on emotion evaluation (TASIT1), social inference - minimal (TASIT2), social inference - enriched (TASIT3), and the RAD tests. These results show a role for this network in both lower-level and higher-level social cognitive processes which are collectively critical for social functioning in everyday life.


Subject(s)
Cognition , Emotions , Facial Expression , Social Behavior , Adult , Brain Mapping , Female , Frontal Lobe/physiology , Healthy Volunteers , Humans , Limbic Lobe/physiology , Magnetic Resonance Imaging , Male , Middle Aged , Parietal Lobe/physiology , Young Adult
11.
Front Pharmacol ; 8: 942, 2017.
Article in English | MEDLINE | ID: mdl-29403372

ABSTRACT

Drug shortages have been identified as a public health problem in an increasing number of countries. This can negatively impact on the quality and efficiency of patient care, as well as contribute to increases in the cost of treatment and the workload of health care providers. Shortages also raise ethical and political issues. The scientific evidence on drug shortages is still scarce, but many lessons can be drawn from cross-country analyses. The objective of this study was to characterize, compare, and evaluate the current systemic measures and legislative and organizational frameworks aimed at preventing or mitigating drug shortages within health care systems across a range of European and Western Asian countries. The study design was retrospective, cross-sectional, descriptive, and observational. Information was gathered through a survey distributed among senior personnel from ministries of health, state medicines agencies, local health authorities, other health or pharmaceutical pricing and reimbursement authorities, health insurance companies and academic institutions, with knowledge of the pharmaceutical markets in the 28 countries studied. Our study found that formal definitions of drug shortages currently exist in only a few countries. The characteristics of drug shortages, including their assortment, duration, frequency, and dynamics, were found to be variable and sometimes difficult to assess. Numerous information hubs were identified. Providing public access to information on drug shortages to the maximum possible extent is a prerequisite for performing more advanced studies on the problem and identifying solutions. Imposing public service obligations, providing the formal possibility to prescribe unlicensed medicines, and temporary bans on parallel exports are widespread measures. A positive finding of our study was the identification of numerous bottom-up initiatives and organizational frameworks aimed at preventing or mitigating drug shortages. The experiences and lessons drawn from these initiatives should be carefully evaluated, monitored, and presented to a wider international audience for careful appraisal. To be able to find solutions to the problem of drug shortages, there is an urgent need to develop a set of agreed definitions for drug shortages, as well as methodologies for their evaluation and monitoring. This is being progressed.

12.
Cereb Cortex ; 27(3): 1748-1757, 2017 03 01.
Article in English | MEDLINE | ID: mdl-26656723

ABSTRACT

Adaptation learning is crucial to maintain precise motor control in face of environmental perturbations. Although much progress has been made in understanding the psychophysics and neurophysiology of sensorimotor adaptation (SA), the time course of memory consolidation remains elusive. The lack of a reproducible gradient of memory resistance using protocols of retrograde interference has even led to the proposal that memories produced through SA do not consolidate. Here, we pursued an alternative approach using resting-state fMRI to track changes in functional connectivity (FC) induced by learning. Given that consolidation leads to long-term memory, we hypothesized that a change in FC that predicted long-term memory but not short-term memory would provide indirect evidence for memory stabilization. Six scans were acquired before, 15 min, 1, 3, 5.5, and 24 h after training on a center-out task under veridical or distorted visual feedback. The experimental group showed an increment in FC of a network including motor, premotor, posterior parietal cortex, cerebellum, and putamen that peaked at 5.5 h. Crucially, the strengthening of this network correlated positively with long-term retention but negatively with short-term retention. Our work provides evidence, suggesting that adaptation memories stabilize within a 6-h window, and points to different mechanisms subserving short- and long-term memory.


Subject(s)
Adaptation, Physiological/physiology , Brain/physiology , Feedback, Sensory/physiology , Memory/physiology , Motor Activity/physiology , Visual Perception/physiology , Brain/diagnostic imaging , Brain Mapping , Female , Humans , Learning/physiology , Magnetic Resonance Imaging , Male , Neural Pathways/diagnostic imaging , Neural Pathways/physiology , Neuropsychological Tests , Psychophysics , Random Allocation , Rest , Time Factors , Young Adult
13.
Cardiol Young ; 27(5): 929-935, 2017 Jul.
Article in English | MEDLINE | ID: mdl-27821197

ABSTRACT

Most young patients with mild-to-moderate aortic stenosis show no symptoms, and sudden death appears only occasionally. We hypothesised that malignant ventricular arrhythmias could be responsible for the high incidence of sudden death in such patients. If multiple factors such as asymptomatic aortic stenosis in association with arrhythmia-provoking agents are involved, could it be sufficient to account for sudden unexpected death? In this study, eight cases of sudden death in young adults, with ages ranging from 22 to 36 years, who had never reported any symptoms that could be related to aortic stenosis, were investigated. Full autopsies were performed, and congenital aortic stenosis in all eight cases was confirmed. DNA testing for channelopathies was negative. Comprehensive toxicological analyses found an electrolyte imbalance, or non-toxic concentrations of amitriptyline, terfenadine, caffeine, and ethanol. Collectively, these results suggest that congenital asymptomatic aortic stenosis without cardiac hypertrophy in young adults is not sufficient to cause sudden death merely on its own; rather, an additional provoking factor is necessary. According to our findings, the provoking factor may be a state of physical or emotional stress, a state of electrolyte imbalance, or even taking a therapeutic dose of a particular drug.


Subject(s)
Aortic Valve Stenosis/complications , Death, Sudden, Cardiac/etiology , Heart Defects, Congenital/complications , Adult , Amitriptyline/blood , Aortic Valve Stenosis/genetics , Arrhythmias, Cardiac/etiology , Autopsy , Caffeine/blood , Ethanol/blood , Female , Heart Defects, Congenital/genetics , Humans , Incidence , Male , Montenegro/epidemiology , Risk Factors , Terfenadine/blood , Young Adult
14.
Acta Chim Slov ; 63(3): 544-59, 2016.
Article in English | MEDLINE | ID: mdl-27640381

ABSTRACT

We report on the combined experimental and computational study of imidazole- and benzimidazole-based corrosion inhibitors containing methyl and/or mercapto groups. Electrochemical measurements and long-term immersion tests were performed on iron in NaCl solution, whilst computational study explicitly addresses the molecular level details of the bonding on iron surface by means of density functional theory calculations (DFT). Experimental data were the basis for the determination of inhibition efficiency and mechanism. Methyl group combined with mercapto group has a beneficial effect on corrosion inhibition at all inhibitor concentrations. The beneficial effect of mercapto group combined with benzene group is not so pronounced as when combined with methyl group. The latter is in stark contrast with the behaviour found previously on copper, where the effect of methyl group was detrimental and that of mercapto and benzene beneficial. Explicit DFT calculations reveal that methyl-group has a small effect on the inhibitor-surface interaction. In contrast, the presence of mercapto group involves the strong S-surface bonding and consequently the adsorption of inhibitors with mercapto group is found to be more exothermic.

15.
J Cogn Neurosci ; 28(7): 971-84, 2016 Jul.
Article in English | MEDLINE | ID: mdl-26942319

ABSTRACT

Recent empirical work suggests that, during healthy aging, the variability of network dynamics changes during task performance. Such variability appears to reflect the spontaneous formation and dissolution of different functional networks. We sought to extend these observations into resting-state dynamics. We recorded EEG in young, middle-aged, and older adults during a "rest-task-rest" design and investigated if aging modifies the interaction between resting-state activity and external stimulus-induced activity. Using multiscale entropy as our measure of variability, we found that, with increasing age, resting-state dynamics shifts from distributed to more local neural processing, especially at posterior sources. In the young group, resting-state dynamics also changed from pre- to post-task, where fine-scale entropy increased in task-positive regions and coarse-scale entropy increased in the posterior cingulate, a key region associated with the default mode network. Lastly, pre- and post-task resting-state dynamics were linked to performance on the intervening task for all age groups, but this relationship became weaker with increasing age. Our results suggest that age-related changes in resting-state dynamics occur across different spatial and temporal scales and have consequences for information processing capacity.


Subject(s)
Aging/physiology , Brain/physiology , Electroencephalography , Rest , Aged , Aging/psychology , Cognition/physiology , Entropy , Female , Humans , Least-Squares Analysis , Male , Middle Aged , Neuropsychological Tests , Reaction Time/physiology , Signal Processing, Computer-Assisted , Young Adult
16.
Neuroimage ; 124(Pt A): 181-193, 2016 Jan 01.
Article in English | MEDLINE | ID: mdl-26318525

ABSTRACT

The emphasis of modern neurobiological theories has recently shifted from the independent function of brain areas to their interactions in the context of whole-brain networks. As a result, neuroimaging methods and analyses have also increasingly focused on network discovery. Magnetoencephalography (MEG) is a neuroimaging modality that captures neural activity with a high degree of temporal specificity, providing detailed, time varying maps of neural activity. Partial least squares (PLS) analysis is a multivariate framework that can be used to isolate distributed spatiotemporal patterns of neural activity that differentiate groups or cognitive tasks, to relate neural activity to behavior, and to capture large-scale network interactions. Here we introduce [MEG]PLS, a MATLAB-based platform that streamlines MEG data preprocessing, source reconstruction and PLS analysis in a single unified framework. [MEG]PLS facilitates MRI preprocessing, including segmentation and coregistration, MEG preprocessing, including filtering, epoching, and artifact correction, MEG sensor analysis, in both time and frequency domains, MEG source analysis, including multiple head models and beamforming algorithms, and combines these with a suite of PLS analyses. The pipeline is open-source and modular, utilizing functions from FieldTrip (Donders, NL), AFNI (NIMH, USA), SPM8 (UCL, UK) and PLScmd (Baycrest, CAN), which are extensively supported and continually developed by their respective communities. [MEG]PLS is flexible, providing both a graphical user interface and command-line options, depending on the needs of the user. A visualization suite allows multiple types of data and analyses to be displayed and includes 4-D montage functionality. [MEG]PLS is freely available under the GNU public license (http://meg-pls.weebly.com).


Subject(s)
Cerebral Cortex/physiology , Image Processing, Computer-Assisted/methods , Magnetoencephalography/methods , Signal Processing, Computer-Assisted , Software , Humans , Least-Squares Analysis
17.
Cereb Cortex ; 26(9): 3851-65, 2016 09.
Article in English | MEDLINE | ID: mdl-26315689

ABSTRACT

Aging is associated with decreased resting-state functional connectivity (RSFC) within the default mode network (DMN), but most functional imaging studies have restricted the analysis to specific brain regions or networks, a strategy not appropriate to describe system-wide changes. Moreover, few investigations have employed operational psychiatric interviewing procedures to select participants; this is an important limitation since mental disorders are prevalent and underdiagnosed and can be associated with RSFC abnormalities. In this study, resting-state fMRI was acquired from 59 adults free of cognitive and psychiatric disorders according to standardized criteria and based on extensive neuropsychological and clinical assessments. We tested for associations between age and whole-brain RSFC using Partial Least Squares, a multivariate technique. We found that normal aging is not only characterized by decreased RSFC within the DMN but also by ubiquitous increases in internetwork positive correlations and focal internetwork losses of anticorrelations (involving mainly connections between the DMN and the attentional networks). Our results reinforce the notion that the aging brain undergoes a dedifferentiation processes with loss of functional diversity. These findings advance the characterization of healthy aging effects on RSFC and highlight the importance of adopting a broad, system-wide perspective to analyze brain connectivity.


Subject(s)
Aging/pathology , Aging/physiology , Brain/anatomy & histology , Brain/physiology , Connectome/methods , Adolescent , Adult , Aged , Cognition Disorders/pathology , Cognition Disorders/physiopathology , Female , Humans , Male , Mental Disorders/pathology , Mental Disorders/physiopathology , Middle Aged , Nerve Net/anatomy & histology , Nerve Net/physiology , Neural Pathways/anatomy & histology , Neural Pathways/physiology , Reference Values , Rest/physiology , Young Adult
18.
PLoS Genet ; 10(8): e1004523, 2014 Aug.
Article in English | MEDLINE | ID: mdl-25122193

ABSTRACT

Face expressions are a rich source of social signals. Here we estimated the proportion of phenotypic variance in the brain response to facial expressions explained by common genetic variance captured by ∼ 500,000 single nucleotide polymorphisms. Using genomic-relationship-matrix restricted maximum likelihood (GREML), we related this global genetic variance to that in the brain response to facial expressions, as assessed with functional magnetic resonance imaging (fMRI) in a community-based sample of adolescents (n = 1,620). Brain response to facial expressions was measured in 25 regions constituting a face network, as defined previously. In 9 out of these 25 regions, common genetic variance explained a significant proportion of phenotypic variance (40-50%) in their response to ambiguous facial expressions; this was not the case for angry facial expressions. Across the network, the strength of the genotype-phenotype relationship varied as a function of the inter-individual variability in the number of functional connections possessed by a given region (R(2) = 0.38, p<0.001). Furthermore, this variability showed an inverted U relationship with both the number of observed connections (R2 = 0.48, p<0.001) and the magnitude of brain response (R(2) = 0.32, p<0.001). Thus, a significant proportion of the brain response to facial expressions is predicted by common genetic variance in a subset of regions constituting the face network. These regions show the highest inter-individual variability in the number of connections with other network nodes, suggesting that the genetic model captures variations across the adolescent brains in co-opting these regions into the face network.


Subject(s)
Brain/physiology , Facial Expression , Genetic Variation , Polymorphism, Single Nucleotide/genetics , Adolescent , Brain/metabolism , Brain Mapping , Female , Humans , Magnetic Resonance Imaging , Male
19.
Eur J Public Health ; 24(3): 385-9, 2014 Jun.
Article in English | MEDLINE | ID: mdl-24287032

ABSTRACT

BACKGROUND: Health inequalities may begin during childhood. The aim of this study was to investigate the main effect of poverty and its interactive effect with gender on children's blood pressure. METHODS: The study was performed in two elementary schools from a rural region near Podgorica, the capital of Montenegro. A questionnaire including questions on family monthly income, children's physical activity and the consumption of junk food was self-administered by parents of 434 children (223 boys and 211 girls) aged 6-13 years. Children's poverty level was assessed using the recommendations from the National Study on Poverty in Montenegro. Children's body weight and height were measured and body mass index-for-gender-and-age percentile was calculated. An oscillometric monitor was used for measurement of children's resting blood pressure in school. RESULTS: A two-factorial analysis of variance with body mass index percentile, physical activity and junk food as covariates showed an interaction of gender and poverty on children's blood pressure, pointing to synergy between poverty and female gender, with statistical significance for raised diastolic pressure (F = 5.462; P = 0.021). Neither physical activity nor the consumption of junk food explained the interactive effect of poverty and gender on blood pressure. CONCLUSION: We show that poverty is linked to elevated blood pressure for girls but not boys, and this effect is statistically significant for diastolic pressure. The results are discussed in the light of gender differences in stress and coping that are endemic to poverty.


Subject(s)
Blood Pressure Determination/methods , Blood Pressure , Hypertension/epidemiology , Poverty , Rural Population , Adolescent , Anthropometry , Blood Pressure Determination/instrumentation , Child , Factor Analysis, Statistical , Female , Humans , Hypertension/etiology , Male , Montenegro/epidemiology , Sex Factors , Surveys and Questionnaires
20.
Neuroimage Clin ; 2: 534-541, 2013 Apr 10.
Article in English | MEDLINE | ID: mdl-24049744

ABSTRACT

In patients with chronic-phase traumatic brain injury (TBI), structural MRI is readily attainable and provides rich anatomical information, yet the relationship between whole-brain structural MRI measures and neurocognitive outcome is relatively unexplored and can be complicated by the presence of combined focal and diffuse injury. In this study, sixty-three patients spanning the full range of TBI severity received high-resolution structural MRI concurrent with neuropsychological testing. Multivariate statistical analysis assessed covariance patterns between volumes of grey matter, white matter, and sulcal/subdural and ventricular CSF across 38 brain regions and neuropsychological test performance. Patients with diffuse and diffuse + focal injury were analyzed both separately and together. Tests of speeded attention, working memory, and verbal learning and memory robustly covaried with a distributed pattern of volume loss over temporal, ventromedial prefrontal, right parietal regions, and cingulate regions. This pattern was modulated by the presence of large focal lesions, but held even when analyses were restricted to those with diffuse injury. Effects were most consistently observed within grey matter. Relative to regional brain volumetric data, clinically defined injury severity (depth of coma at time of injury) showed only weak relation to neuropsychological outcome. The results showed that neuropsychological test performance in patients with TBI is related to a distributed pattern of volume loss in regions mediating mnemonic and attentional processing. This relationship holds for patients with and without focal lesions, indicating that diffuse injury alone is sufficient to cause significant neuropsychological disability in relation to regional volume loss. Quantified structural brain imaging data provides a highly sensitive index of brain integrity that is related to cognitive functioning in chronic phase TBI.

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