Vemurafenib combined with cladribine and cytarabine results in durable remission of pediatric BRAF V600E-positive LCH.

Langerhans cell histiocytosis (LCH) is a disorder with a variety of clinical signs. The most severe forms affect risk organs (RO). The established role of the BRAF V600E mutation in LCH led to a targeted approach. However, targeted therapy cannot cure the disease, and cessation leads to quick relapses. Here, we combined cytosine-arabinoside (Ara-C) and 2'-chlorodeoxyadenosine (2-CdA) with targeted therapy to achieve stable remission. Nineteen children were enrolled in the study: 13 were RO-positive (RO+) and 6 RO-negative (RO-). Five patients received the therapy upfront, whereas the other 14 received it as a second or third line. The protocol starts with 28 days of vemurafenib (20 mg/kg), which is followed by 3 courses of Ara-C and 2-CdA (100 mg/m2 every 12 h, 6 mg/m2 per day, days 1-5) with concomitant vemurafenib therapy. After that, vemurafenib therapy was stopped, and 3 courses of mono 2-CdA followed. All patients rapidly responded to vemurafenib: the median disease activity score decreased from 13 to 2 points in the RO+ group and from 4.5 to 0 points in the RO- group on day 28. All patients except 1 received complete protocol treatment, and 15 of them did not have disease progression. The 2-year reactivation/progression-free survival (RFS) for RO+ was 76.9% with a median follow-up of 21 months and 83.3% with a median follow-up of 29 months for RO-. Overall survival is 100%. Importantly, 1 patient experienced secondary myelodysplastic syndrome after 14 months from vemurafenib cessation. Our study demonstrates that combined vemurafenib plus 2-CdA and Ara-C is effective in a cohort of children with LCH, and the toxicity is manageable. This trial is registered at www.clinicaltrials.gov as NCT03585686.

Association of lifetime major depressive disorder with enhanced attentional sensitivity measured with P3 response in young adult twins.

Major depression is associated with alterations in the auditory P3 event-related potential (ERP). However, the persistence of these abnormalities after recovery from depressive episodes, especially in young adults, is not well known. Furthermore, the potential influence of substance use on this association is poorly understood. Young adult twin pairs (N = 177) from the longitudinal FinnTwin16 study were studied with a psychiatric interview, and P3a and P3b ERPs elicited by task-irrelevant novel sounds and targets, respectively. Dyadic linear mixed-effect models were used to distinguish the effects of lifetime major depressive disorder from familial factors and effects of alcohol problem drinking and tobacco smoking. P3a amplitude was significantly increased and P3b latency decreased, in individuals with a history of lifetime major depression, when controlling the fixed effects of alcohol abuse, tobacco, gender, twins' birth order, and zygosity. These results suggest that past lifetime major depressive disorder may be associated with enhanced attentional sensitivity.

Vemurafenib provides a rapid and robust clinical response in pediatric Langerhans cell histiocytosis with the BRAF V600E mutation but does not eliminate low-level minimal residual disease per ddPCR using cell-free circulating DNA.

BACKGROUND: Langerhans cell histiocytosis (LCH) is a disease that arises from myeloid cells that phenotypically resemble Langerhans cells (LC), which is typically driven by the BRAF V600E mutation. High-risk LCH has a poor prognosis. PROCEDURE: Fifteen children with BRAF V600E + LCH received vemurafenib between March 2016 and February 2020. The median age at LCH onset was 2 months and the median age at the start of vemurafenib treatment was 22 months. The median disease activity score (DAS) at the start of vemurafenib treatment was 12 points. RESULTS: The median duration of vemurafenib treatment was 29 months. All patients responded to treatment, with median DAS of 4 points at week 4 and 1 point at 6 months. Two patients died: 1 of hepatic failure after NSAID overdose and 1 of neutropenic sepsis. Cessation of vemurafenib resulted in relapse in 5 patients and was only possible for 1 patient. Serial measurements of BRAF V600E using cell-free circulating DNA revealed that 7 patients had persistently high mutant allele levels. CONCLUSION: Vemurafenib is effective in children with BRAF V600E + LCH. However, treatment with vemurafenib does not eradicate the disease and its long-term toxicity has not been established.

Fibrin-based Bioinks: New Tricks from an Old Dog.

For the past 10 years, the main efforts of most bioprinting research teams have focused on creating new bioink formulations, rather than inventing new printing set-up concepts. New tissue-specific bioinks with good printability, shape fidelity, and biocompatibility are based on "old" (well-known) biomaterials, particularly fibrin. While the interest in fibrin-based bioinks is constantly growing, it is essential to provide a framework of material's properties and trends. This review aims to describe the fibrin properties and application in three-dimensional bioprinting and provide a view on further development of fibrin-based bioinks.

Oscillatory activity of the human cerebellum: the intracranial electrocerebellogram revisited.

The functional electrophysiology of the human cerebellum remains poorly characterized. Existing knowledge originates primarily from lesion studies and increasingly from hemodynamic measures such as functional magnetic resonance imaging, along with some evidence in recent years from transcranial magnetic stimulation. In this context, we revisit the few existing records of intracranial recordings from the human cerebellum, and uncover additional little-known reports - three from the Soviet Union, published in Russian between 1949 and 1951, and one from Belgium, published in French in 1964. These studies together demonstrate electrical rhythms of the human cerebellar cortex at frequencies as high as 250 Hz, including task-related modulations. A reanalysis of their electrode traces with state-of-the-art spectral analysis techniques confirm the reported frequency bands, and showed that these modulations were sustained for 100-200 ms. These remarkable observations from the early ages of intracranial mapping of the human brain are in line with recent electrophysiological studies of oscillations in the rodent cerebellum as well as magnetoencephalographic findings in humans. Time-frequency analyses have provided valuable insight into the function of cerebral cortex, and may prove even more critical for the differing neurophysiology of the cerebellum. We contend that these insights will be invaluable to bridge the role of oscillatory networks in the cerebellum with those of cerebral cortex in mediating perception, action, and cognition and to investigate possible cerebellar involvement in neurological dysfunction.

Association between tryptophan hydroxylase-2 genotype and the antidepressant effect of citalopram and paroxetine on immobility time in the forced swim test in mice.

Tryptophan hydroxylase-2 (TPH2) is the rate limiting enzyme of serotonin synthesis in the brain. The 1473G allele of the C1473G polymorphism in mTPH2 gene is associated with reduced enzyme activity and serotonin synthesis rate in the mouse brain. Here, the influence of the 1473G allele on the antidepressant effect of selective serotonin reuptake inhibitors (SSRIs), citalopram (2.5 or 5.0mg/kg) and paroxetine (5.0 or 10.0mg/kg), in the forced swim test was studied using B6-1473G and B6-1473C congenic mouse lines with the 1473G (decreased TPH2 activity) or 1473C (normal TPH2 activity) alleles, respectively, transferred to the genome of C57BL/6 mouse strain. Paroxetine (5.0 or 10.0mg/kg) and citalopram (2.5 or 5.0mg/kg) decreased immobility time in B6-1473C mice, while both doses of paroxetine and 2.5mg/kg of citaloprame did not alter immobility time in B6-1473G mice. However, 5.0mg/kg of citalopram reduced immobility in B6-1473G mice. The results provided genetic evidence of moderate association between 1473G allele and reduced sensitivity to SSRIs in mice.

A longitudinal twin study of effects of adolescent alcohol abuse on the neurophysiology of attention and orienting.

BACKGROUND: Long-term functional brain effects of adolescent alcohol abuse remain uncertain, partially because of difficulties in distinguishing inherited deficits from neuronal effects of ethanol and by confounds associated with alcohol abuse, especially nicotine exposure. We conducted a longitudinal twin study to determine neurocognitive effects of adolescent alcohol abuse, as measured with the auditory event-related potential (ERP) component P3, a putative marker of genetic vulnerability to alcoholism. METHODS: Twin pairs (N=177; 150 selected for intrapair concordance/discordance for alcohol-related problems at age 18½) were recruited from ongoing studies of twins born 1975-1979 in Finland. Alcohol and tobacco use were assessed with questionnaires at ages 16, 17, 18½, and ~25, and by a structured psychiatric interview concurrent with the ERP testing at mean age 25.8. During ERP recordings, subjects were instructed to detect target tones within a train of frequent "standards" and to ignore occasional "novel" sounds. To distinguish familial factors from ethanol effects, ERP and self-reported alcohol use measures were incorporated into hierarchical multiple regression (HMR) analysis, and intrapair differences in ERP were associated with intra-pair differences in alcohol variables. RESULTS: Novel-sound P3 amplitude correlated negatively with self-reported alcohol use in both between- and within-family analyses. No similar effect was observed for target-tone P3. HMR results suggest that twins' similarity for novel-sound P3 amplitude is modulated by their alcohol use, and this effect of alcohol use is influenced by genetic factors. CONCLUSIONS: Our results, from a large sample of twins selected from a population-based registry for pairwise concordance/discordance for alcohol problems at 18½, demonstrate that adolescent alcohol abuse is associated with subtle neurophysiological changes in attention and orienting. The changes are reflected in decreased novel-sound P3 amplitude and may be modified by genetic factors.

Somatosensory working memory performance in humans depends on both engagement and disengagement of regions in a distributed network.

Successful working memory (WM) requires the engagement of relevant brain areas but possibly also the disengagement of irrelevant areas. We used magnetoencephalography (MEG) to elucidate the temporal dynamics of areas involved in a somatosensory WM task. We found an increase in gamma band activity in the primary and secondary somatosensory areas during encoding and retention, respectively. This was accompanied by an increase of alpha band activity over task-irrelevant regions including posterior and ipsilateral somatosensory cortex. Importantly, the alpha band increase was strongest during successful WM performance. Furthermore, we found frontal gamma band activity that correlated both with behavioral performance and the alpha band increase. We suggest that somatosensory gamma band activity reflects maintenance and attention-related components of WM operations, whereas alpha band activity reflects frontally controlled disengagement of task-irrelevant regions. Our results demonstrate that resource allocation involving the engagement of task-relevant and disengagement of task-irrelevant regions is needed for optimal task execution.

C1473G polymorphism in mouse tph2 gene is linked to tryptophan hydroxylase-2 activity in the brain, intermale aggression, and depressive-like behavior in the forced swim test.

Tryptophan hydroxylase-2 (TPH2) is the rate-limiting enzyme of brain serotonin synthesis. The C1473G polymorphism in the mouse tryptophan hydroxylase-2 gene affects the enzyme's activity. In the present study, we investigated the linkage between the C1473G polymorphism, enzyme activity in the brain, and behavior in the forced swim, intermale aggression, and open field tests using mice of the C57BL/6 (C/C) and CC57BR/Mv (G/G) strains and the B6-1473C (C/C) and B6-1473G (G/G) lines created by three successive backcrossings on C57BL/6. Mice of the CC57BR/Mv strain had decreased brain enzyme activity, aggression intensity, and immobility in the forced swim test, but increased locomotor activity and time spent in the central part of the open field arena compared with animals of the C57BL/6 strain. Mice of the B6-1473G line homozygous for the 1473G allele had lower TPH2 activity in the brain, aggression intensity, and immobility time in the forced swim test compared with animals of the B6-1473C line homozygous for the 1473C allele. No differences were found between the B6-1473G and B6-1473C mice in locomotor activity and time spent in the central part of the arena in the open field test. Thus, the C1473G polymorphism is involved in the determination of TPH2 activity and is linked to aggression intensity and forced-swim immobility in mice. At the same time, the polymorphism does not affect locomotion and anxiety-related behavior in the open field test. The B6-1473C and B6-1473G mice represent a valuable experimental model for investigating molecular mechanisms of serotonin-related behavior.

Gamma power is phase-locked to posterior alpha activity.

Neuronal oscillations in various frequency bands have been reported in numerous studies in both humans and animals. While it is obvious that these oscillations play an important role in cognitive processing, it remains unclear how oscillations in various frequency bands interact. In this study we have investigated phase to power locking in MEG activity of healthy human subjects at rest with their eyes closed. To examine cross-frequency coupling, we have computed coherence between the time course of the power in a given frequency band and the signal itself within every channel. The time-course of the power was calculated using a sliding tapered time window followed by a Fourier transform. Our findings show that high-frequency gamma power (30-70 Hz) is phase-locked to alpha oscillations (8-13 Hz) in the ongoing MEG signals. The topography of the coupling was similar to the topography of the alpha power and was strongest over occipital areas. Interestingly, gamma activity per se was not evident in the power spectra and only became detectable when studied in relation to the alpha phase. Intracranial data from an epileptic subject confirmed these findings albeit there was slowing in both the alpha and gamma band. A tentative explanation for this phenomenon is that the visual system is inhibited during most of the alpha cycle whereas a burst of gamma activity at a specific alpha phase (e.g. at troughs) reflects a window of excitability.

Utilization of a two-standard system in real-time PCR for quantification of gene expression in the brain.

In this study, we applied for real-time PCR the two-standard system that we had worked out previously for PCR with gel-detection of products. Genomic DNA of a known concentration was used as external standard and mRNA of the DNA-dependent RNA-polymerase II was used as internal standard. It was shown that PCR with gel-detection of products and real-time PCR provide similar results and demonstrate almost identical accuracy and repeatability when the two-standard system is used. With the help of the both methods and using the two-standard system we have confirmed the link between the genetically determined freezing reaction in mice and reduced 5-HT1A receptor mRNA level in the midbrain. We have also found that the genetically determined freezing reaction in mice is not connected with changes in Tph2 gene expression.

Delayed auditory processing underlying stimulus detection in Down syndrome.

Down syndrome (DS) is characterized by intellectual disability and development of dementia that are attributed to similar neuropathological features as observed in Alzheimer's disease (AD). The aim of this study was to investigate whether DS patients have similar impairment of preattentive auditory processing as observed in AD. Sinusoidal tones were presented to DS patients and healthy controls, and evoked auditory evoked fields (AEF) were measured with a whole-head magnetoencephalography (MEG) system. Patients with DS had significantly delayed and attenuated N100m, and delayed but not attenuated P50m responses over both hemispheres. Present results indicate that preattentive auditory processing underlying stimulus detection is impaired in DS. Given that anticholinergic drugs modulate AEFs, degeneration of cholinergic system in DS could contribute to the damaged auditory processing.

Inherited auditory-cortical dysfunction in twin pairs discordant for schizophrenia.

BACKGROUND: Information on the inheritance of neurophysiological abnormalities might help elucidate the molecular genetic basis of schizophrenia. We used magnetoencephalography (MEG) and electroencephalography (EEG) to investigate the inheritance of auditory-cortical deficiencies in twin pairs discordant for schizophrenia. METHODS: Auditory EEG/MEG responses to frequent standard and occasional deviant tones were measured in mono- and dizygotic (MZ and DZ) twin pairs discordant for schizophrenia and demographically matched healthy twin pairs, recruited from a total population cohort. The MEG/EEG results were regressed against the genetic resemblance to patients with schizophrenia across the patients' unaffected MZ/DZ co-twins and control subjects (with genetic correlations of 1, .5, and 0 to schizophrenia patients, respectively). RESULTS: The EEG responses P50, N100, and mismatch negativity (MMN), as well as the MEG response P50m, were reduced in the schizophrenic patients. P50 and N100 were significantly decreased also in their unaffected co-twins, as compared with the control subjects. Importantly, the P50 and N100 decrease correlated with the unaffected subjects' genetic resemblance to schizophrenia patients. CONCLUSIONS: Our results suggest inherited abnormalities in cortical auditory processing in schizophrenia, reflected by the decreased P50/P50m and N100 amplitudes, whereas the MMN abnormalities might reflect predominantly state-dependent neurodegeneration.

Enhanced magnetic auditory steady-state response in early Alzheimer's disease.

OBJECTIVE: Previous studies have reported abnormalities in both spontaneous and evoked electromagnetic brain activity in Alzheimer's disease (AD). We studied the auditory steady-state response (SSR) which represents the net effect of entrained background activity and superimposed cortical evoked responses, in AD patients and healthy controls. METHODS: Whole-head magnetoencephalography (MEG) was used to measure SSR to monaural 40-Hz stimulation in AD patients and age-matched controls. Equivalent current dipoles (ECD) of the SSR were modeled in each hemisphere, and source amplitudes were compared between the two groups using time-varying ECD models. RESULTS: Our results indicate that the SSR is significantly increased in AD patients with mild to moderate cognitive deterioration in comparison with healthy elderly subjects. CONCLUSIONS: Goal-directed functioning requires optimization of inhibitory and excitatory inputs in the cortex, allowing the adaptation of responsiveness to repetitive stimulation with low relevance. The present results suggest that this balance is impaired in AD, manifesting itself in decreased inhibition in cortical auditory processing and impaired adaptation of the stimulus-locked activity, probably due to abnormalities in cholinergic modulation. SIGNIFICANCE: MEG appears to be a sensitive tool to detect abnormalities of auditory processing already in early stages of AD.

Source estimation of spontaneous MEG oscillations in mild cognitive impairment.

Mild cognitive impairment (MCI) is a memory disorder often preceding Alzheimer's disease (AD). AD has been shown to be associated with abnormal generation of spontaneous electromagnetic activity. We investigated whether the cortical generation of spontaneous brain oscillations in MCI shows changes resembling those observed in AD. A minimum current estimates algorithm was applied to identify cortical sources of magnetoencephalographic (MEG) spontaneous brain oscillations in male MCI patients with a clear memory disorder and in healthy elderly controls. This data was subsequently compared to a male subsample of AD patients from an earlier study. While there were clear oscillatory abnormalities in AD patients, there was no evidence of significant changes in the alpha source distribution in MCI patients as compared to healthy controls. Deficits in the distribution of oscillatory sources in the resting state are thus likely to occur at later stages of cognitive impairment than MCI.

Theta and gamma oscillations predict encoding and retrieval of declarative memory.

Although studies in animals and patients have demonstrated that brain oscillations play a role in declarative memory encoding and retrieval, little has been done to investigate the temporal dynamics and sources of brain activity in healthy human subjects performing such tasks. In a magnetoencephalography study using pictorial stimuli, we have now identified oscillatory activity in the gamma (60-90 Hz) and theta (4.5-8.5 Hz) band during declarative memory operations in healthy participants. Both theta and gamma activity was stronger for the later remembered compared with the later forgotten items (the "subsequent memory effect"). In the retrieval session, theta and gamma activity was stronger for recognized items compared with correctly rejected new items (the "old/new effect"). The gamma activity was also stronger for recognized compared with forgotten old items (the "recognition effect"). The effects in the theta band were observed over right parietotemporal areas, whereas the sources of the effects in the gamma band were identified in Brodmann area 18/19. We propose that the theta activity is directly engaged in mnemonic operations. The increase in neuronal synchronization in the gamma band in occipital areas may result in a stronger drive to subsequent areas, thus facilitating both memory encoding and retrieval. Alternatively, the gamma synchronization might reflect representations being reinforced by top-down activity from higher-level memory areas. Our results provide additional insight on human declarative memory operations and oscillatory brain activity that complements previous electrophysiological and brain imaging studies.

Altered generation of spontaneous oscillations in Alzheimer's disease.

Slowing of spontaneous alpha oscillations and an anterior shift of a source of alpha activity (8-13 Hz) have been consistently reported in the EEG studies of Alzheimer's disease (AD). It is unknown whether these changes are associated with a gradual shift in location and frequency of existing sources or rather with the involvement of a new set of oscillators. We addressed this question by applying source modeling (minimum current estimates, MCE) to spontaneous alpha activity recorded with a 306-channel MEG system from eleven non-medicated AD patients with mild to moderate cognitive impairment and twelve age-matched controls during the eyes-closed session. AD patients had predominant lower alpha band sources in the temporal regions, whereas in the controls, robust alpha sources were found near the parieto-occipital sulcus. Activation within the parieto-occipital region was significantly weaker, and activation in the right temporal area was significantly enhanced in the AD patients. These results suggest an increased temporal-lobe contribution coinciding with parieto-occipital deficits. We propose that MCE, which provides simultaneous mapping of several oscillatory sources, might be useful for detecting neurophysiological abnormalities associated with AD in combination with other neuropsychological and neurological measures.

Magnetoencephalographic evidence of abnormal auditory processing in amyotrophic lateral sclerosis with bulbar signs.

OBJECTIVE: Amyotrophic lateral sclerosis (ALS) is characterized by progressive motor neuron damage that gives rise to muscle denervation. Besides motor neuron damage, conscious auditory processing appears to be impaired in ALS, whereas it has remained ambiguous whether preceding automatic auditory processing is abnormal in ALS and specifically in ALS with bulbar signs. METHODS: Auditory evoked fields (AEFs) to monaurally presented frequent and infrequent tones with stimulus intervals of 500 and 2500 ms were recorded with magnetoencephalography (MEG) from 10 ALS patients having bulbar signs and from 10 age-matched healthy subjects. RESULTS: The amplitudes of the P50m and N100m responses, which index automatic auditory processing underlying stimulus detection, were significantly increased and P50m latency was shortened in ALS patients. MMNm, which reflects memory-based auditory comparison process, was increased in amplitude in the patient group, whereas the MMNm latency was similar in both groups. AEF latency and amplitude values failed to correlate with the severity of ALS as measured by ALS Functional Rating Scale (ALSFRS). CONCLUSIONS: The present results suggest that auditory processing underlying stimulus detection, and subsequent memory-based comparison processes are abnormal in ALS patients with severe bulbar signs. This might be due to cortical overactivity of excitatory neurotransmitter glutamate observed in ALS.

Effects of scopolamine on MEG spectral power and coherence in elderly subjects.

OBJECTIVE: Scopolamine, a muscarinic receptor antagonist, can produce temporary cognitive impairments as well as electroencephalographic changes that partially resemble those observed in Alzheimer's disease. In order to test the sensitivity of spectral power and hemispheric coherence to changes in cholinergic transmission, we evaluated quantitative magnetoencephalogram (MEG) after intravenous injection of scopolamine. METHODS: MEG of 8 elderly healthy subjects (59-80 years) were measured with a whole-head magnetometer after intravenous injection of scopolamine. An injection of glycopyrrolate, a peripheral muscarinic antagonist, was used as the placebo in a double-blind, randomized, cross-over design. Spectral power and coherence were computed over 7 brain regions in 3 frequency bands. RESULTS: Scopolamine administration increased theta activity (4-8 Hz) and resulted in the abnormal pattern of MEG desynchronization in eyes-open vs. eyes-closed conditions in the alpha band (8-13 Hz). These effects were most prominent over the posterior regions. Interhemispheric and left intrahemispheric coherence was significantly decreased in the theta band (4-8 Hz). CONCLUSIONS: Spontaneous cortical activity at the theta and alpha range and functional coupling in the theta band are modulated by the cholinergic system. MEG may provide a tool for monitoring brain dynamics in neurological disorders associated with cholinergic abnormalities.