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W ramach badań nad wydłużaniem trwałości soków drzewnych stosowano dotychczas chemiczne dodatki do żywności. W niniejszej pracy podjęto próbę przeprowadzenia mikrofiltracji soku brzozowego. Trzymiesięczny test przechowalniczy dwunastu próbek prowadzony był w temperaturze pokojowej, zaś badanym parametrem była tzw. gęstość optyczna. Sześć próbek nie było poddanych mikrofiltracji, zaś sześć kolejnych mikrofiltrowano za pomocą jałowych filtrów, w jałowych warunkach i do jałowych naczyń. Uzyskane wyniki wskazują, że mikrofiltrowany sok brzozowy pozostaje trwały przez okres co najmniej trzech miesięcy, bez oznak zmętnienia i przy utrzymującej się przez ten czas zerowej gęstości optycznej. Z kolei próbki niepoddane mikrofiltracji uległy zmętnieniu już po upływie jednego dnia od rozpoczęcia testu przechowalniczego, co jest charakterystyczne dla mikrobiologicznego rozkładu surowca. Zaprezentowane rozwiązanie może stać się podstawą wdrożenia w przemyśle spożywczym, dzięki któremu będzie można dostarczyć konsumentowi sok brzozowy o znacznie wydłużonej trwałości, jednak bez dodatku substancji chemicznych.
The effect of stimuli predicting danger (DS) and safety (SS) in Pavlovian aversive conditioning on hippocampal local field potentials (LFP) was studied in 25 partially restrained adult male rats (Long-Evans). DS lasting 5 s preceded tail-shock, while SS overlapping DS during DS last 3 s predicted omission of shock. The power spectra of LFPs during trials were analyzed in theta and delta frequency bands. In DS, theta frequency during the last 3 s was lower that in first 2 s. In danger and safety situation theta peak frequency was different for dorsal CA1 activity (5.99 Hz vs. 6.86 Hz, respectively), while delta peak frequency was different for ventral CA1 (1.56 Hz vs. 1.07 Hz) for the last 3 s of trial. Differences in theta frequency in danger and safety situation may reflect differences in sensory processing during induced emotional states and/ or related differences in motor behavior.
INTRODUCTION: Dysfunction of the brain glutamatergic system is supposed to be one of fundamental causes underlying the schizophrenia. Administration of NMDA receptor antagonist (eg. MK801) leads to occurrence of various symptoms of that disease, inter alia, disruption of cognitive functions. AIM(S): The main aim of our study was to verify whether emotional/cognitive processes disturbed by local administration of MK801 into the basolateral amygdala (BLA) were associated with changes in electrical activity of two limbic structures: BLA and nucleus accumbens (NAc). METHOD(S): Experiments were done according to a classical fear conditioning paradigm. During consecutive sessions we recorded Local Field Potentials (LFPs) and videotaped the behavior of animals. Three experiments were performed: A) control (no pharmacological intervention), B) with MK801 infusion into BLA and C) with MK801 infusion and clozapine injection (i.p.). In experiments B and C animals were divided into two groups: drugs were administered 1) before acquisition sessions or 2) before first three extinction sessions. Power spectra were calculated for frequency bands: delta, theta, beta 1, beta 2, low gamma and high gamma during freezing and non-freezing behaviour for two time segments: during and after conditioned stimulus presentation. RESULTS: Analysis of data revealed that in experiment (BII) MK801 infusion disrupted extinction process. In experiment (CII) clozapine did not influence the delayed extinction of conditioned response. Most differences between band powers were found for theta, beta 1 and 2 bands, with increase in power in consecutive sessions in both experiments (A, B). In experiment C the greatest power was observed in sessions with clozapine. CONCLUSIONS: The same behavior (freezing) was associated by various patterns of differences between power spectra. The increasing power of theta, beta 1 and 2 bands in experiments A and B may indicate increasing level of attention. FINANCIAL SUPPORT: Funding: the National Center of Science (Poland) DEC-2011/03/B/NZ4/03768.
BACKGROUND AND AIMS: The basolateral complex of amygdala (BLA) and nucleus accumbens (NAc) are involved in acquisition and extinction of the conditioned fear. The aim of our study was to verify if the electrical activity of these structures is correlated with the behavior of rats during fear conditioning after tetrodotoxin (TTX) blockade of BLA. The disturbances of cognitive function (learning) were estimated on the basis of the conditioned fear response. METHODS: Male Wistar rats were implanted with electrodes in right NAc and BLA, guides bilaterally in BLA and divided in 2 groups: A-TTX group (TTX infused before acquisition sessions), E-TTX group (TTX before the first 3 extinction sessions). As a CS we used a tone associated at the end with electric shock (acquisition) or a tone alone (extinction). During each session we recorded local field potentials (LFPs) in NAc and BLA. The number of boli and rat behavior (video) were also recorded. RESULTS: Infusion of TTX resulted in longest freezing duration both in A-TTX and E-TTX groups. In the A-TTX group the number of boli in acquisition sessions was smaller than in extinction sessions, while in the E-TTX group it was greater than in extinction sessions. The number of boli in all sessions was higher in the E-TTX group. Analysis of LFPs showed that in the A-TTX group there were practically no differences in frequency bands power between all sessions. The same analysis for the E-TTX group showed many differences between all sessions. CONCLUSIONS: Our results are in line with previous data that blockade of BLA during acquisition sessions prevents conditioning, and at LFP level the activity was not different between sessions. Results of the group E-TTX show that the activity in BLA and NAc is changing parallel to changes in behavior what may reflect neural processes involved in acquisition and extinction of conditioned response. Project funded by the National Center of Science DEC-2011/03/B/ NZ4/03768.
Single-stranded DNA-binding proteins (SSBs) play essential roles in DNA replication, recombination, and repair in bacteria, archaea and eukarya. The SSBs share a common core ssDNA-binding domain with a conserved OB (oligonucleotide/oligosaccharide binding) fold. This ssDNA-binding domain was presumably present in the common ancestor to all three major branches of life. In recent years, there has been an increasing interest in SSBs because they are useful for molecular biology methods and for analytical purposes. In this review, we concentrate on recent advances in the discovery of new sources of SSBs as well as certain aspects of their applications in analytical sciences.
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