Search

Purpose: Mechanistic target of rapamycin (mTOR) complex 1 (mTORC1) regulates cell growth in response to nutritional status. Central to the mTORC1 function is the Rag-GTPase heterodimer. One component of the Rag heterodimer is RagC (Ras-related GTP-binding protein C), which is encoded by the RRAGC gene., Methods: Genetic testing via trio exome sequencing was applied to identify the underlying disease cause in 3 infants with dilated cardiomyopathy, hepatopathy, and brain abnormalities, including pachygyria, polymicrogyria, and septo-optic dysplasia. Studies in patient-derived skin fibroblasts and in a HEK293 cell model were performed to investigate the cellular consequences., Results: We identified 3 de novo missense variants in RRAGC (NM_022157.4: c.269C>A, p.(Thr90Asn), c.353C>T, p.(Pro118Leu), and c.343T>C, p.(Trp115Arg)), which were previously reported as occurring somatically in follicular lymphoma. Studies of patient-derived fibroblasts carrying the p.(Thr90Asn) variant revealed increased cell size, as well as dysregulation of mTOR-related p70S6K (ribosomal protein S6 kinase 1) and transcription factor EB signaling. Moreover, subcellular localization of mTOR was decoupled from metabolic state. We confirmed the key findings for all RRAGC variants described in this study in a HEK293 cell model., Conclusion: The above results are in line with a constitutive overactivation of the mTORC1 pathway. Our study establishes de novo missense variants in RRAGC as cause of an early-onset mTORopathy with unfavorable prognosis., Competing Interests: Conflict of Interest The authors declare no conflicts of interest., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

The effects of lexical meaning and lexical familiarity on auditory deviance detection were investigated by presenting oddball sequences of words, while participants ignored the stimuli. Stimulus sequences were composed of words that were varied in word class (nouns vs. functions words) and frequency of language use (high vs. low frequency) in a factorial design with the roles of frequently presented stimuli (Standards) and infrequently presented ones (Deviants) were fully crossed. Deviants elicited the Mismatch Negativity component of the event-related brain potential. Modulating effects of lexical meaning were obtained, revealing processing advantages for denotationally meaningful items. However, no effect of word frequency was observed. These results demonstrate that an apparently low-level function, such as auditory deviance detection utilizes information from the mental lexicon even for task-irrelevant stimuli., (Copyright © 2021 Elsevier Inc. All rights reserved.)

The interactions of graphene oxide (GO), a 2-dimensional nanomaterial with hydrophilic edges, hydrophobic basal plane and large flat surfaces, with biological macromolecules, are of key importance for the development of novel nanomaterials for biomedical applications. To gain more insight into the interaction of GO flakes with human serum albumin (HSA), we examined GO binding to HSA in its isolated state and in blood plasma. Calorimetric data reveal that GO strongly stabilizes free isolated HSA against a thermal challenge at low ionic strength, indicating strong binding interactions, confirmed by the drop in ζ-potential of the HSA/GO assemblies compared to bare GO flakes. However, calorimetry also revealed that the HSA-GO molecular interaction is hampered in blood plasma, the ionic strength being particularly important for the interactions. Molecular modelling calculations are in full concert with these experimental findings, indicating a considerably higher binding affinity for HSA to GO in its partially unfolded state, characteristic to low-ionic-strength environment, than for the native protein conformation, observed under physiological conditions. Therefore, for the first time we demonstrate an impeded interaction between HSA and GO nanoflakes in blood plasma, and suggest that the protein is protected from the plausible toxic effects of GO under native conditions., Competing Interests: Declaration of competing interest All authors declare no competing interests., (Copyright © 2021 Elsevier B.V. All rights reserved.)

It has been hypothesized that age-related hearing loss is caused not only by peripheral but also central changes in the auditory system. Many studies used event-related potentials (ERPs) elicited by sound onsets to characterize the age-related differences in central auditory processing. Age-related ERP enhancements in such studies have often been interpreted in terms of elevated sensitivity to auditory stimulation. Such ERPs, however, comprise various components reflecting different aspects of auditory and task-related processing. The composition of the waveforms may considerably differ for ERPs elicited by other auditory events. In the present study, ERPs elicited by tone offsets were used to characterize processing differences between younger and older adults in a short-go, tone-duration discrimination paradigm. Whereas the onset-related auditory ERP was enhanced in the older adult group, no age-related differences were found in the offset-related auditory ERPs observable at temporal electrodes. In older adults, however, offset-related processing was dominated by an N2 that could reflect enhanced cognitive control activities. Because N2 was present regardless discrimination difficulty, younger adults may have framed the task as offset detection, whereas older adults represented the task as "genuine" discrimination., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Infrequent, salient stimuli often capture attention despite their task-irrelevancy, and disrupt on-going goal-directed behavior. A number of studies show that presenting cues signaling forthcoming deviants reduces distraction, which may be a "by-product" of cue-processing interference or the result of direct preparatory processes for the forthcoming distracter. In the present study, instead of "bursts" of cue information, information on the temporal structure of the stimulus sequence was provided. Young adults performed a spatial discrimination task where complex tones moving left or right were presented. In the predictable condition, every 7th tone was a pitch-deviant, while in the random condition the position of deviants was random with a probability of 1/7. Whereas the early event-related potential correlates of deviance-processing (N1 and MMN) were unaffected by predictability, P3a amplitude was significantly reduced in the predictable condition, indicating that prevention of distraction was based on the knowledge about the temporal structure of the stimulus sequence., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Hsp27 belongs to the small heat shock protein family, which are ATP-independent chaperones. The most important function of Hsp27 is based on its ability to bind non-native proteins and inhibit the aggregation of incorrectly folded proteins maintaining them in a refolding-competent state. Additionally, it has anti-apoptotic and antioxidant activities. To study the effect of Hsp27 on memory and synaptic functions, amyloid-β (Aβ) accumulation, and neurodegeneration, we generated transgenic mice overexpressing human Hsp27 protein and crossed with APPswe/PS1dE9 mouse strain, a mouse model of Alzheimer's disease (AD). Using different behavioral tests, we found that spatial learning was impaired in AD model mice and was rescued by Hsp27 overexpression. Electrophysiological recordings have revealed that excitability of neurons was significantly increased, and long-term potentiation (LTP) was impaired in AD model mice, whereas they were normalized in Hsp27 overexpressing AD model mice. Using anti-amyloid antibody, we counted significantly less amyloid plaques in the brain of APPswe/PS1dE9/Hsp27 animals compared to AD model mice. These results suggest that overexpression of Hsp27 protein might ameliorate certain symptoms of AD.

Stimulus-focused attention enhances the processing of auditory stimuli, which is indicated by enhanced neural activity. In situations where fast responses are required, attention may not only serve as a means to gain more information about the relevant stimulus, but it may provide a processing speed gain as well. In two experiments we investigated whether attentional focusing decreased the latency of the auditory N1 event related potential. In Experiment 1 slowly emerging, soft (20dB sensation level) sounds were presented in two conditions, in which participants performed a sound-detection task or watched a silent movie and ignored the sounds. N1 latency was shorter in the sound-detection task in comparison to the ignore condition. In Experiment 2 we investigated whether the attentional N1 latency-decrease was caused by a frequency-specific attentional preparation or not. To this end, tone sequences were presented with a single tone frequency or with four different frequencies. N1 latency was shorter in the sound-detection task in comparison to the ignore condition regardless the number of frequencies. These results suggest that stimulus-focused attention increases stimulus processing speed by generally increasing sensory gain., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Involuntary attention switches triggered by infrequent, unpredictably occurring sensory events (distraction) can be prevented when participants are made aware of the forthcoming distractor. Previous studies exploring this phenomenon presented visual cues before each stimulus in an auditory oddball sequence. In one condition, cues were completely reliable in predicting the forthcoming distractor or standard sound, in another, separate condition, they were completely unreliable. These studies found that in the condition with reliable cues, distraction was reduced compared to that with unreliable cues, as signaled by decreased reaction time delay as well as reduced P3a and reorienting negativity event-related potentials. Whereas these results are generally interpreted as the results of preparatory processes initiated by the cues, it could be argued that the preventive effect is a byproduct of increased information processing load in the condition with informative cues compared to that in the condition with uninformative ones. In the present study, using 80% reliable visual cues preceding tones in an oddball sequence, it was demonstrated that distraction can be prevented when the trials with valid and invalid cues were presented within a single experimental condition, as shown by reduced reaction time delay and P3a amplitude. These results are compatible with the notion that the distraction is prevented by means of preparatory processes initiated by the cues., (Copyright © 2011 Elsevier B.V. All rights reserved.)

The safety of an açai (Euterpe oleracea Mart.) pulp enriched fruit and berry juice, MonaVie Active®, fortified with the functional ingredient, glucosamine, was studied. The beverage was found not to be mutagenic, clastogenic, cytotoxic, or genotoxic, as determined by the bacterial reverse mutation assay, chromosomal aberration assay, mouse micronucleus assay, and mammalian cell gene mutation (L5178Y) assay. The single dose LD50 based on a 14-day acute oral toxicity study is greater than 20,000 mg/kg bw, the highest dose tested. In a repeat dose 90-day oral subchronic toxicity study by gavage, 220 animals were randomly assigned to a control group, an untreated group, or one of three experimental groups (10, 20 and 40 g/kg bw). No treatment-related significant changes in body weight, food and water consumption, ophthalmology, organ weights, urinanalysis, hematological and clinical chemistry, or gross pathology, were observed in surviving animals compared to the control groups. Three animals died midway through the observation period (male, 20 g/kg bw/day; male 40 g/kg bw/day; and, female, 10 g/kg bw/day). These animals died without preceding clinical symptoms, histopathological lesions, or evidence of injury to tissue or organs except for signs of suffocation/aspiration congestion, which was concluded to be due to problems with the gavage administration of the fluid test article, and not due to the test article itself. The NOEAL was determined to be 40 g/kg bw/day for male and female rats, which was the highest dose tested. Phylloquinone (vitamin K1) content averaged 21.7 μg/100 g, comparable to amounts found in iceberg lettuce. In conclusion, the results provide additional experimental evidence that MonaVie Active® juice is non-toxic., (Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.)

The dietary supplement, 112 Degrees, was formulated with the goal of supporting sexual functioning in men. Due to rampant problems with drug adulteration for this category of products, a comprehensive screening for active pharmaceutical agents, with an emphasis on drugs prescribed for erectile dysfunction such as type 5 phosphodiesterase (PDE-5) inhibitors, and known unapproved PDE-5 drug analogues, was performed along with preclinical toxicology studies prior to the introduction of this product into the marketplace. 112 Degrees was found to be free of all pharmaceutical adulterants tested, and was not mutagenic, clastogenic, or genotoxic as demonstrated by the Ames test, chromosomal aberration assay, and mouse micronucleus assay, respectively. The LD(50) in the 14-day acute oral toxicity study was greater than 5000 mg/kg, the highest dose tested., ((c) 2009 Elsevier Inc. All rights reserved.)

Behavioral and event-related potential measures of distraction and reorientation were obtained from children (6 years), young (19-24 years) and elderly adults (62-82 years) in an auditory distraction-paradigm. Participants performed a go/nogo duration discrimination task on a sequence of short and long (50-50%) tones. In children, reaction times were longer and discrimination (d') scores were lower than in adults. Occasionally (15%), the pitch of the presented tones was changed. The task-irrelevant feature variation resulted in longer reaction times and lower d' scores with no significant differences between the three groups. Task-irrelevant changes affected the N1 amplitude and elicited the mismatch negativity, N2b, P3 and reorienting negativity (RON) sequence of event-related brain potentials. In children, the P3 latency was the same as in young adults. However the RON component was delayed by about 100ms. In the elderly, P3 and RON were uniformly delayed by about 80ms compared to young adults. This pattern of results provides evidence that distraction influences different processing stages in the three groups. Restoration of the task-optimal attention set was delayed in children, whereas in the elderly, the triggering of involuntary attention-switching required longer time.

Integration of information across time is an essential part of auditory processing. Evidence from a variety of experiments support the notion of an approximately 200-ms long time window following the onset of a sound, during which a unitary sound representation is formed (the temporal window of integration, TWI). The temporal resolution in the auditory system is assumed to decrease with aging suggesting that the duration of the TWI may be longer in elderly than young adults. The TWI duration was assessed in young and elderly adults using the oddball paradigm in which a regular auditory event (standard) is occasionally exchanged for a different event (deviant). Previous studies showed that when the stimulus onset asynchrony (SOA) exceeds the duration of the TWI, two successive deviations occurring infrequently in a repetitive sound sequence elicit two separate mismatch negativity (MMN) event-related brain potentials. However, only one MMN is elicited when the SOA is shorter than the TWI. Experiment 1 tested MMN elicitation for the second of two successive deviant sounds as a function of the SOA. Experiment 2 used the sound omission paradigm, in which MMN is only elicited by omissions when the SOA is shorter than the TWI. Again, MMN elicitation was tested by infrequent tone omissions as a function of the SOA. Results showed no significant differences between elderly and younger participants as a function of SOA. This suggests that the duration of the TWI is approximately between 200 and 250 ms in both groups of subjects. On the other hand, the lower MMN amplitudes elicited by frequency deviation in the elderly compared with the younger participants suggest that the specificity of frequency representation deteriorates with aging.

The effects of lexicality on auditory change detection based on auditory sensory memory representations were investigated by presenting oddball sequences of repeatedly presented stimuli, while participants ignored the auditory stimuli. In a cross-linguistic study of Hungarian and German participants, stimulus sequences were composed of words that were language-familiar, lexical, meaningful in Hungarian but language-unfamiliar, not lexical, meaningless in German, and words with the opposite characteristics. The roles of frequently presented stimuli (Standards) and infrequently presented one (Deviants) were fully crossed. Language-familiar and language-unfamiliar Deviants elicited the Mismatch Negativity component of the event-related brain potential. We found differences in processes of change detection depending on whether the Standard was language-familiar, or not. Whereas, the lexicality of the Deviant had no effect on the processes of change detection. Also, language-familiar Standards processed differently than language-unfamiliar ones. We suggest that pre-attentive (default) tuning to meaningful words sets up language-specific preparatory processes that affect change detection in speech sequences.

Teutsch G. and Bélanger A. treated 5alpha,10alpha epoxides with Grignard-reagents catalyzed by copper(I) ions. The reaction with steroidal epoxides proceeded with complete regio- and stereospecificity, leading exclusively to the 11beta-substituted compounds. According to our synthetic strategy, the 5,10 epoxide isomers were not separated; instead, the pure 11beta, and in some cases, 11alpha-substituted molecules were isolated after the conjugate addition of the Grignard-reagents, followed by deketalization and dehydration. Surprisingly, appearance of a third compound was generally observed beside the expected deprotected products, and this compound turned out to have a 3-keto-5(10),9(11) structural unit. Starting from pure 3-ethylenedioxy-5alpha,10alpha-epoxy-estr-9(11)-ene-17-one and 3-ethylenedioxy-5beta,10beta-epoxy-estr-9(11)-ene-17-one, four model compounds were synthesized (11alpha- and 11beta-[4-[1,1-(ethylenedioxy)-ethyl]phenyl]-estra-, as well as 11alpha- and 11beta-cyclohexyl-estra-derivatives) to study the process of deprotection and dehydration. 3-keto-5(10),9(11)-derivatives were found to form after deketalization and dehydration only from 11alpha-substituted derivatives, while 11beta-derivatives resulted in only the expected 3-keto-5,9-diene structure. After observing this remarkable difference between the behavior of 11alpha-, 11beta-substituted isomers we decided to take a closer look at the processes of deketalization and dehydration. In order to carry out the hydrolysis under mild conditions, pyridinium paratoluenesulfonate, a weakly acidic salt, was applied. All the intermediate products observed by TLC were isolated. The outcome of the deprotection and elimination reactions can be rationalized by two factors: conjugation of olefins (with the 3-oxo-group or the 11-phenyl group) and orientation of groups to be eliminated.

17-formyl-androst-16-ene and its analogues were synthesized from the corresponding 17-iodo-16-ene derivatives in palladium-catalyzed formylation reaction using tributyltin hydride as hydrogen source under mild reaction conditions. The formation of androst-16-ene and its isomerization products, as well as that of analogous steroidal olefins as side-products, was found to be dependent on the reaction conditions. The formylation reaction tolerates various functional groups on the A and B rings of the steroids., (Copyright 2002 Elsevier Science Inc.)

Steroidal dienes were synthesised by Stille-coupling of the corresponding alkenyl iodides with vinyltributyltin under microwave irradiation in a domestic microwave oven in drastically reduced reaction times. Rate acceleration was observed also in the one-pot Stille-coupling-Diels-Alder reaction of 17-iodo-5alpha-androst-16-ene. Stereoselectivity of cycloaddition was slightly improved with diethyl maleate as the dienophile, compared to that achieved with thermal heating.

Homogeneous catalytic hydrazinocarbonylation of some steroid derivatives possessing iodo-alkenyl moiety (17-iodo-androst-16-ene 1, 17-iodo-3-methoxy-estra-1,3,5(10),16-tetraene 2, 17-iodo-4-aza-4-methyl-androst-16-en-3-one 3 and 17-iodo-6beta-hydroxy-3alpha,5alpha-cycloandrost-16-ene 4) were carried out in the presence of a palladium catalyst, a base and acetic or benzoic hydrazide as the nucleophilic reagent. The corresponding N-acetamido-carbamoyl 1a-4a or N-benzamido-carbamoyl derivatives 1b-4b were obtained in high yields. Some of these derivatives served as starting materials for the synthesis of new steroidal 1,3,4-oxadiazole compounds.

Heck reactions of some steroid derivatives possessing iodo-alkenyl moiety (17-iodo-androst-16-ene, 1, 17-iodo-4-aza-4-methyl-androst-16-en-3-one, 2, 17-iodo-4-aza-androst-16-en-3-one, 3) were carried out in the presence of palladium catalysts using various olefins (methyl acrylate, ethyl methacrylate, allyl alcohol and allyl acetate) as coupling partners. With methyl acrylate, a side reaction was observed: the coupling product underwent a Diels-Alder reaction with the excess of methyl acrylate resulting in a six-membered carbocyclic E-ring. Reaction conditions of the synthesis of the Heck-product were optimized. Although the coupling with allyl alcohol led to the formation of 21-formyl-16-pregnene derivatives, the synthesis of the corresponding steroidal unsaturated alcohol could be achieved only via hydrolysis of the coupling product of the alkenyl iodide with allyl acetate.

17-Iodo-delta 16 steroids undergo selective dimerization and carbonylative dimerization in the presence of palladium catalysts in dimethylformamide which result in 16-17'-coupled dienes and 17-carboxylic anhydrides, respectively. Moderate to good yields have been obtained for both types of dimers.

Direct and carbonylative coupling reactions of various steroid derivatives possessing iodo- and bromo-alkenyl moiety (17-iodo-androst-16-ene, 1, 17-bromoandrost-2,16-diene, 2, 17-iodo-4-aza-4-methylandrost-16-en-3-one, 3, 17-iodo-4-azaandrost-16-en-3-one, 4) with vinyltributylstannane and ethynyltributylstannane were carried out in the presence of various palladium catalysts. While carbonylation took place only with vinyltributylstannane, 17-vinyl-, and 17-ethynyl-delta 16 steroids were produced via direct coupling with vinyltributylstannane and ethynyltributylstannane, respectively. Activities of some catalysts based on Pd(0) and Pd(II) precursors were compared, and Pd(PPh3)4 was found to be superior to other complexes in most cases. In the coupling of 17-iodoandrost-16-ene with organostannanes Pd2(dba)3 + 8 AsPh3 in situ catalyst was found to be even more effective.

The palladium-catalyzed coupling of various 17-iodo-delta 16 steroids (17-iodo-androst-16-ene, 17-iodo-4-methyl-4-aza-androst-16-en-3-one, and 17-iodo-4-aza-androst-16-en-3-one) with dialkyl phosphites (dimethyl phosphite, diethyl phosphite, and diisopropyl phosphite) was examined in detail. The only successful condition for homogeneous coupling involved carrying out the reaction in the absence of any solvents. A large excess of dialkyl phosphite was used, which means that the phosphite itself acted as a solvent. Eight new androst-16-ene derivatives with phosphonate groups at C-17 were synthesized and characterized. These steroids are of pharmacological interest as potential 5 alpha-reductase inhibitors. Under the same conditions, methylation of lactam NH was observed using dimethyl phosphite.

A series of new somatostatin analogs have been developed and tested for antitumor activity. Some analogs strongly inhibited tyrosine kinase activity of human colon tumor cells and this activity correlated well with their antiproliferative effect, but did not correlate with GH release inhibition. The best analogs strongly inhibited the metastasis formation in the Lewis lung metastasis model in mice. On the basis of these in vitro and in vivo data we were able to select one analog with strong tyrosine kinase inhibitory and antitumor activity, without inhibiting growth hormone release.