Real-time change detection of steady-state evoked potentials

Steady-state evoked potentials (SSEP) are the electrical activity recorded from the scalp in response to high-rate sensory stimulation. SSEP consist of a constituent frequency component matching the stimulation rate, whose amplitude and phase remain constant with time and are sensitive to functional changes in the stimulated sensory system. Monitoring SSEP during neurosurgical procedures allows identification of an emerging impairment early enough before the damage becomes permanent. In routine practice, SSEP are extracted by averaging of the EEG recordings, allowing detection of neurological changes within approximately a minute. As an alternative to the relatively slow-responding empirical averaging, we present an algorithm that detects changes in the SSEP within seconds. Our system alerts when changes in the SSEP are detected by applying a two-step Generalized Likelihood Ratio Test (GLRT) on the unaveraged EEG recordings. This approach outperforms conventional detection and provides the monitor with a statistical measure of the likelihood that a change occurred, thus enhancing its sensitivity and reliability. The system’s performance is analyzed using Monte Carlo simulations and tested on real EEG data recorded under coma.     

Extensive land cover change across Arctic–Boreal Northwestern North America from disturbance and climate forcing

A multitude of disturbance agents, such as wildfires, land use, and climate‐driven expansion of woody shrubs, is transforming the distribution of plant functional types across Arctic–Boreal ecosystems, which has significant implications for interactions and feedbacks between terrestrial ecosystems and climate in the northern high‐latitude. However, because the spatial resolution of existing land cover datasets is too coarse, large‐scale land cover changes in the Arctic–Boreal region (ABR) have been poorly characterized. Here, we use 31 years (1984–2014) of moderate spatial resolution (30 m) satellite imagery over a region spanning 4.7 × 10⁶ km² in Alaska and northwestern Canada to characterize regional‐scale ABR land cover changes. We find that 13.6 ± 1.3% of the domain has changed, primarily via two major modes of transformation: (a) simultaneous disturbance‐driven decreases in Evergreen Forest area (?14.7 ± 3.0% relative to 1984) and increases in Deciduous Forest area (+14.8 ± 5.2%) in the Boreal biome; and (b) climate‐driven expansion of Herbaceous and Shrub vegetation (+7.4 ± 2.0%) in the Arctic biome. By using time series of 30 m imagery, we characterize dynamics in forest and shrub cover occurring at relatively short spatial scales (hundreds of meters) due to fires, harvest, and climate‐induced growth that are not observable in coarse spatial resolution (e.g., 500 m or greater pixel size) imagery. Wildfires caused most of Evergreen Forest Loss and Evergreen Forest Gain and substantial areas of Deciduous Forest Gain. Extensive shifts in the distribution of plant functional types at multiple spatial scales are consistent with observations of increased atmospheric CO₂ seasonality and ecosystem productivity at northern high‐latitudes and signal continental‐scale shifts in the structure and function of northern high‐latitude ecosystems in response to climate change.     

Toxicity to crustacea due to polypeptide-phospholipase interaction in the venom of a chactoid scorpion

The toxic factors to isopods (crustacea) were isolated from the venom of the chactoid scorpion Scorpio maurus palmatus (Scorpionidae) by the aid of column chromatography, and their purity was assessed by disc electrophoresis, analytical ultracentrifugation, isoelectrofocusing, and amino acid analysis. The toxicity to isopods is attributed to two groups of components: (a) Low-molecular-weight basic polypeptides possessing about 3 and 8% of the crude venom lethality and paralytic potency to isopods, respectively. These components are characterized by very similar and unique amino acid compositions of 31 to 34 amino acids with molecular mass of about 3.5 kDa and a deficiency in methionine, leucine, phenylalanine, histidine, and tryptophan. (b) Toxic phospholipases are also toxic to insect but not to mammals. A lethal phospholipase which contained 37% of the total venom phospholipase activity and 11% of its toxicity to isopods was purified. This phospholipase consists of 125 amino acids (Mr 14,581) and is a hydrophobic, acidic protein composed of two isoenzymes (pI 4.7 and 4.9). This enzyme demonstrates an A2-type positional specificity (EC 3.1.1.4) with pH and temperature optima of 7.5-8.0 and 40-50 degrees C, respectively, and high calcium requirements. The lethal potency of the basic polypeptides is evidently increased by the addition of low, sublethal doses of the pure phospholipase. Such synergism was not observed with regards to their paralytic activity. The pharmacological significance of these data is discussed.     

Formulation of N-acetylputrescine and N1-acetylspermidine in cultured human lymphocytes.

N-Acetylputrescine and N1-acetylspermidine were synthesized from putrescine in cultured human lymphocytes. They were identified by paper chromatography and t.l.c. Acetylputrescine was also identified by mass spectrometry. N-Acetylputrescine and N1-acetylspermidine were formed in untreated cells and in lectin-transformed cells.     

Co-expression Profiling of Autism Genes in the Mouse Brain

Autism spectrum disorder (ASD) is one of the most prevalent and highly heritable neurodevelopmental disorders in humans. There is significant evidence that the onset and severity of ASD is governed in part by complex genetic mechanisms affecting the normal development of the brain. To date, a number of genes have been associated with ASD. However, the temporal and spatial co-expression of these genes in the brain remain unclear. To address this issue, we examined the co-expression network of 26 autism genes from AutDB (http://mindspec.org/autdb.html), in the framework of 3,041 genes whose expression energies have the highest correlation between the coronal and sagittal images from the Allen Mouse Brain Atlas database (http://mouse.brain-map.org). These data were derived from in situ hybridization experiments conducted on male, 56-day old C57BL/6J mice co-registered to the Allen Reference Atlas, and were used to generate a normalized co-expression matrix indicating the cosine similarity between expression vectors of genes in this database. The network formed by the autism-associated genes showed a higher degree of co-expression connectivity than seen for the other genes in this dataset (Kolmogorov–Smirnov P = 5×10⁻²⁸). Using Monte Carlo simulations, we identified two cliques of co-expressed genes that were significantly enriched with autism genes (A Bonferroni corrected P<0.05). Genes in both these cliques were significantly over-expressed in the cerebellar cortex (P = 1×10⁻⁵) suggesting possible implication of this brain region in autism. In conclusion, our study provides a detailed profiling of co-expression patterns of autism genes in the mouse brain, and suggests specific brain regions and new candidate genes that could be involved in autism etiology.     

Inception and Five-year Run of a Semen Cryobank. Clinical and Behavioral Aspects

Recent developments in infertility treatment, as well as medical and ethical concern to preserve the fertilizing ability of male subjects potentially at risk, led to the inception of a sperm cryobank in our medical center in 1996. Up to the end of the year 2000, 64 young men displaying higher semen values than generally required were accepted as donors, while 305 married (mean age 32.5, range 22–54) and 381 single women (mean age 41.2, range 27–50) were treated by artificial insemination donor (AID), resulting in 251 conceptions. Besides, 437 male subjects aged 15–61 requested sperm cryopreservation. Methodological considerations about sperm cryopreservation, and behavioral implications therefrom, are evaluated.