INTRODUCTION: We used a functional MRI paradigm involving conventional vs. unconventional views of objects to assess bottom-up vs. top-down visual processing in Parkinson's disease (PD) with normal cognition, PD with mild cognitive impairment (MCI), and MCI due to Alzheimer's disease (AD) as compared to healthy controls. We particularly aimed at determining whether the task discriminated between PD with and without MCI and between two MCI groups due to distinct pathologies (AD and PD). METHODS: 116 right-handed subjects (21 MCI due to AD; 16 PD with normal cognition; 24 PD with MCI; 55 healthy controls) performed a visual object-matching task in a T MR scanner. T statistic maps were computed to contrast task-based activation during unconventional vs. conventional view conditions. One-way ANOVAs and post hoc tests were performed to assess differences across and between groups. RESULTS: Both MCI groups performed worse than controls in the unconventional views condition and showed reduced activation of right anterior cingulate cortex and right superior parietal lobule (PD with MCI), and right middle and inferior frontal gyri (MCI due to AD). Neural responses in cortical areas within the ventral and dorsal visual pathway appeared to be preserved in both MCI groups. Receiver operating characteristic analysis of MRI contrast in the right superior parietal lobule distinguished PD with and without MCI with 87.50% sensitivity and 86.98% specificity. CONCLUSIONS: Impaired recognition of objects presented in unconventional orientations in MCI due to PD and AD was associated with decreased activation of frontoparietal regions, consistent with defective top-down regulation of visual processing. Aberrant activation of superior parietal cortex may serve as an early imaging biomarker of impending cognitive impairment in PD.

• MeSH
• Alzheimerova nemoc patofyziologie   psychologie   MeSH
• kognitivní dysfunkce patofyziologie   psychologie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• magnetická rezonanční tomografie MeSH
• mapování mozku MeSH
• mozek patofyziologie   MeSH
• Parkinsonova nemoc patofyziologie   psychologie   MeSH
• rozpoznávání (psychologie) MeSH
• rozpoznávání obrazu fyziologie   MeSH
• senioři MeSH
• světelná stimulace MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

The relative contribution of top-down and bottom-up processes regulating primary decomposers can influence the strength of the link between the soil animal community and ecosystem functioning. Although soil bacterial communities are regulated by bottom-up and top-down processes, the latter are considered to be less important in structuring the diversity and functioning of fungal-dominated ecosystems. Despite the huge diversity of mycophagous (fungal-feeding) soil fauna, and their potential to reverse the outcomes of competitive fungal interactions, top-down grazing effects have never been found to translate to community-level changes. We constructed soil mesocosms to investigate the potential of isopods grazing on cord-forming basidiomycete fungi to influence the community composition and functioning of a complex woodland soil microbial community. Using metagenomic sequencing we provide conclusive evidence of direct top-down control at the community scale in fungal-dominated woodland soil. By suppressing the dominant cord-forming basidiomycete fungi, isopods prevented the competitive exclusion of surrounding litter fungi, increasing diversity in a community containing several hundred fungal species. This isopod-induced modification of community composition drove a shift in the soil enzyme profile, and led to a restructuring of the wider mycophagous invertebrate community. We highlight characteristics of different soil ecosystems that will give rise to such top-down control. Given the ubiquity of isopods and basidiomycete fungi in temperate and boreal woodland ecosystems, such top-down community control could be of widespread significance for global carbon and nutrient cycling.

• MeSH
• fungální proteiny genetika   metabolismus   MeSH
• houby klasifikace   enzymologie   fyziologie   MeSH
• Isopoda fyziologie   MeSH
• půda chemie   MeSH
• půdní mikrobiologie * MeSH
• regulace genové exprese enzymů MeSH
• regulace genové exprese u hub MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The objective is to study the involvement of the posterior medial cortex (PMC) in encoding and retrieval by visual and auditory memory processing. Intracerebral recordings were studied in two epilepsy-surgery candidates with depth electrodes implanted in the retrosplenial cingulate, precuneus, cuneus, lingual gyrus and hippocampus. We recorded the event-related potentials (ERP) evoked by visual and auditory memory encoding-retrieval tasks. In the hippocampus, ERP were elicited in the encoding and retrieval phases in the two modalities. In the PMC, ERP were recorded in both the encoding and the retrieval visual tasks; in the auditory modality, they were recorded in the retrieval task, but not in the encoding task. In conclusion, the PMC is modality dependent in memory processing. ERP is elicited by memory retrieval, but it is not elicited by auditory encoding memory processing in the PMC. The PMC appears to be involved not only in higher-order top-down cognitive activities but also in more basic, rather than bottom-up activities.

• MeSH
• akustická stimulace MeSH
• dospělí MeSH
• elektroencefalografie metody   MeSH
• epilepsie patofyziologie   MeSH
• implantované elektrody MeSH
• lidé MeSH
• mozek fyziologie   MeSH
• paměť fyziologie   MeSH
• počítačové zpracování signálu MeSH
• sluchové evokované potenciály fyziologie   MeSH
• světelná stimulace MeSH
• zrakové evokované potenciály fyziologie   MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mužské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

BACKGROUND: The default mode network (DMN) decreases its activity when switching from a resting state to a cognitive task condition, while activity of the network engaged in the given task increases. Visual processing is typically disturbed in Parkinson's disease dementia (PDD). OBJECTIVE: Using functional MRI, we studied the DMN effective connectivity patterns in PDD as compared with cognitively normal patients with Parkinson's disease (PD) and healthy controls (HC) when switching from baseline to a visual cognitive task condition. METHODS: In all, 14 PDD, 18 PD, and 18 age-matched healthy controls participated in this functional MRI study. We used a psychophysiological interaction analysis with the precuneus (PCu) as a seed. The threshold was set at p(FWE) <0.05. RESULTS: The healthy controls showed greater PCu connectivity with the bilateral middle temporal/middle occipital gyri at baseline than during the task condition. The correlation direction changed from positive to negative. Both PD and PDD showed disturbed DMN connectivity with the brain regions that are involved in bottom-up visual processing. In PD, we also found impaired integration of the areas engaged in the ventral attentional network, which might reflect specific attentional deficits observed during the early course of PD. In mild PDD, we detected increased engagement of areas involved in the dorsal attentional network, which corresponds to increased top-down control in this patient group as compared to the healthy controls. CONCLUSION: Our results show impaired dynamic interplay between large scale brain networks in PD that spread far beyond the motor system.

• MeSH
• atrofie etiologie   patologie   MeSH
• hyperkinetická porucha etiologie   MeSH
• kognitivní poruchy etiologie   patologie   MeSH
• kyslík krev   MeSH
• lidé středního věku MeSH
• lidé MeSH
• magnetická rezonanční tomografie MeSH
• mapování mozku MeSH
• modely neurologické MeSH
• nervové dráhy krevní zásobení   patologie   MeSH
• neuropsychologické testy MeSH
• Parkinsonova nemoc komplikace   patologie   MeSH
• počítačové zpracování obrazu MeSH
• poruchy zraku etiologie   patologie   MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• studie případů a kontrol MeSH
• světelná stimulace MeSH
• temenní lalok krevní zásobení   patologie   MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Nešpecifické zápalové ochorenia čreva, čiže Crohnova choroba a ulcerózna kolitída, patria medzi ochorenia, ktoré postihujú najmä osoby v produktívnom veku. Môžu mať komplikácie, ktorých riešenie je často chirurgické a svojím priebehom, symptómami, ako aj komplikáciami znižujú u postihnutých pacientov kvalitu života. V klasickom tzv. step up liečebnom postupe má svoje miesto biologická liečba až po zlyhaní ostatnej konvenčnej liečby. V poslednom období sa ukazuje, že jej skoršie zaradenie do liečebného procesu u niektorých pacientov môže pozitívne ovplyvniť priebeh ochorenia. Hovoríme o tzv. top down postupe.

Nonspecific inflammatory bowel disease, or Crohn's disease and ulcerative colitis, are among the diseases that mainly affect people in working age. Affected patients may have complications solving of which is often surgical and by its course, symptoms as well as by complications it deteriorates their quality of life. In the classical, so-called “step up” treatment procedure biological therapy comes just after failure of other conventional treatments. Recently it appears that earlier inclusion of biological therapy in the therapeutical process may positively influence the course of the disease in some patients. This approach is the so-called “top down” process.

• MeSH
• politika MeSH
• vytváření politiky MeSH
• Publikační typ
• monografie MeSH

• Konspekt
• Politologie
• NLK Obory
• politologie, politika, zdravotní politika

Combining a minimum food web model with Arctic microbial community dynamics, we have suggested that top-down control by copepods can affect the food web down to bacterial consumption of organic carbon. Pursuing this hypothesis further, we used the minimum model to design and analyse a mesocosm experiment, studying the effect of high (+Z) and low (-Z) copepod density on resource allocation, along an organic-C addition gradient. In the Arctic, both effects are plausible due to changes in advection patterns (affecting copepods) and meltwater inputs (affecting carbon). The model predicts a trophic cascade from copepods via ciliates to flagellates, which was confirmed experimentally. Auto- and heterotrophic flagellates affect bacterial growth rate and abundance via competition for mineral nutrients and predation, respectively. In +Z, the model predicts low bacterial abundance and activity, and little response to glucose; as opposed to clear glucose consumption effects in -Z. We observed a more resilient bacterial response to high copepods and demonstrate this was due to changes in bacterial community equitability. Species able to use glucose to improve their competitive and/or defensive properties, became predominant. The observed shift from a SAR11-to a Psychromonodaceae - dominated community suggests the latter was pivotal in this modification of ecosystem function. We argue that this group used glucose to improve its defensive or its competitive abilities (or both). Adding such flexibility in bacterial traits to the model, we show how it creates the observed resilience to top-down manipulations observed in our experiment.

• MeSH
• autotrofní procesy MeSH
• Bacteria růst a vývoj   izolace a purifikace   metabolismus   MeSH
• Ciliophora fyziologie   MeSH
• Copepoda fyziologie   MeSH
• fyziologie bakterií * MeSH
• glukosa metabolismus   MeSH
• heterotrofní procesy MeSH
• mikrobiota MeSH
• potravní řetězec * MeSH
• uhlík metabolismus   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Arktida MeSH

V tomto článku je zpracován přehled biologické terapie idiopatických střevních zánětů, a to včetně popsání jejich mechanismů působení a indikací. Shrnuty jsou aktuální výsledky klinického hodnocení účinnosti biologické terapie, současné znalosti o slizničním hojení, léčbě gravidních pacientek či o vlivu biologické léčby na fertilitu. Diskutovány jsou rovněž problematické situace v terapii idiopatických střevních zánětů biologiky – např. strategie step-up a top- down, cílené ukončení či optimalizace biologické léčby, rozvoj sekundární rezistence, výskyt nežádoucích účinků či komplikací, druhotná ztráta léčebné odpovědi, rozvoj protilátek nebo autoimunitních procesů.

An overview of the biological therapy of inflammatory bowel disease is presented, a description of their mechanisms of action and indications are included. Recent results of the clinical evaluation of the efficacy of biological therapy, current knowledge of mucosal healing, treatment of pregnant patients or the effect of biological therapy on fertility are summarized. Problematic situations during biological treatment of inflammatory bowel disease are also discussed – for example, step-up and top-down strategies, termination or optimization of biological therapy, development of secondary resistance, the occurrence of adverse events or complications, secondary loss of response, development of antibodies or autoimmune processes.

Posledné roky vniesli viacej svetla do poznania patogenézy Crohnovej choroby. Nové poznatky sú spoľahlivou základňou pre pochopenie súčasnej liečby, ale aj pre rozvoj nových liečebných stratégií. Cieľom nových biologických látok je primárna selektívna interakcia s kľúčovými procesmi črevného zápalu. V súčasnej dobe sa pre klinickú prax odporúča len protilátka proti TNF-alfa infliximab. Pozornosť je dnes zameriavaná na načasovanie použitia biologickej liečby (top-down alebo step-up). Zatiaľ sa jej včasné použitie deje v rámci klinických štúdií. Napriek tomu môže byť vhodná ako prvolíniová liečba u čerstvo diagnostikovaných pacientov s ťažkou formou Crohnovej choroby u dospelých aj detí.

Over the last few years, much light has been shed on the pathogenesis of Crohn´s disease. Further knowledge in this field has provided a firm basis not only for understanding of current treatment but also for development of new therapeutic strategies. The aim of these new agents is primary selective interaction with key processes of intestinal inflammation. At present, only anti-tumor necrosis factor-alfa antibodies namely infliximab, is licensed for clinical practice. The attention is focused on the early (top-down) or late (step-up) use of biological agents. As yet, early use of biological agents remains to be supported by convincing evidence, nevertheless it may be advocated as first-line therapy for newly diagnosed severe Crohn´s disease patients, both adults and children.

Cognitive control processes play an essential role not only in controlling actions but also in guiding attentional selection processes. Interestingly, these processes are strongly affected by organizational principles of the cerebral cortex and related functional asymmetries, but the neurobiological foundations are elusive. We ask whether neurobiological mechanisms that affect functional cerebral asymmetries will also modulate effects of top-down control processes on functional cerebral asymmetries. To this end, we examined potential effects of the imprinted gene leucine-rich repeat transmembrane neuronal 1 (LRRTM1) on attentional biasing processes in a forced attention dichotic listening task in 983 healthy adult participants of Caucasian descent using the "iDichotic smartphone app." The results show that functional cerebral asymmetries in the language domain are associated with the rs6733871 LRRTM1 polymorphism when cognitive control and top-down attentional mechanisms modulate processes in bottom-up attentional selection processes that are dependent on functional cerebral asymmetries. There is no evidence for an effect of LRRTM1 on functional cerebral asymmetries in the language domain unrelated to cognitive control processes. The results suggest that cognitive control processes are an important factor to consider when being interested in the molecular genetic basis of functional cerebral architecture.

• MeSH
• akustická stimulace metody   MeSH
• dospělí MeSH
• funkční lateralita fyziologie   MeSH
• jazyk (prostředek komunikace) MeSH
• kognice fyziologie   MeSH
• lidé MeSH
• membránové proteiny genetika   MeSH
• mladiství MeSH
• mladý dospělý MeSH
• mozková kůra fyziologie   MeSH
• pozornost fyziologie   MeSH
• proteiny nervové tkáně genetika   MeSH
• průzkumy a dotazníky MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH