Analysis of the action mechanisms and targets of herbal anticonvulsants highlights opportunities for therapeutic engagement with refractory epilepsy

Epilepsy is a neurological disorder characterized by spontaneous and recurring seizures. It poses significant therapeutic challenges due to diverse etiology, pathobiology, and pharmacotherapy-resistant variants. The anticonvulsive effects of herbal leads with biocompatibility and toxicity considerations have attracted much interest, inspiring mechanistic analysis with the view of their use for engagement of new targets and combination with antiseizure pharmacotherapies. This article presents a comprehensive overview of the key molecular players and putative action mechanisms of the most common antiepileptic herbals demonstrated in tissue culture and preclinical models. From the review of the literature, it emerges that their effects are mediated via five distinct mechanisms: (1) reduction of membrane excitability through inhibition of cation channels, (2) improvement of mitochondrial functions with antioxidant effects, (3) enhancement in synaptic transmission mediated by GABAA receptors, (4) improvement of immune response with anti-inflammatory action, and (5) suppression of protein synthesis and metabolism. While some of the primary targets and action mechanisms of herbal anticonvulsants (1, 3) are shared with antiseizure pharmacotherapies, herbal leads also engage with distinct mechanisms (2, 4, and 5), suggesting new drug targets and opportunities for their integration with antiseizure medications. Addressing outstanding questions through research and in silico modeling should facilitate the future use of herbals as auxiliary therapy in epilepsy and guide the development of treatment of pharmacoresistant seizures through rigorous trials and regulatory approval.

Neurotoxin-Derived Optical Probes for Biological and Medical Imaging

The superb specificity and potency of biological toxins targeting various ion channels and receptors are of major interest for the delivery of therapeutics to distinct cell types and subcellular compartments. Fused with reporter proteins or labelled with fluorophores and nanocomposites, animal toxins and their detoxified variants also offer expanding opportunities for visualisation of a range of molecular processes and functions in preclinical models, as well as clinical studies. This article presents state-of-the-art optical probes derived from neurotoxins targeting ion channels, with discussions of their applications in basic and translational biomedical research. It describes the design and production of probes and reviews their applications with advantages and limitations, with prospects for future improvements. Given the advances in imaging tools and expanding research areas benefiting from the use of optical probes, described here resources should assist the discovery process and facilitate high-precision interrogation and therapeutic interventions.

Molecular Biomarkers of Neuronal Injury in Epilepsy Shared with Neurodegenerative Diseases

In neurodegenerative diseases, changes in neuronal proteins in the cerebrospinal fluid and blood are viewed as potential biomarkers of the primary pathology in the central nervous system (CNS). Recent reports suggest, however, that level of neuronal proteins in fluids also alters in several types of epilepsy in various age groups, including children. With increasing evidence supporting clinical and sub-clinical seizures in Alzheimer's disease, Lewy body dementia, Parkinson's disease, and in other less common neurodegenerative conditions, these findings call into question the specificity of neuronal protein response to neurodegenerative process and urge analysis of the effects of concomitant epilepsy and other comorbidities. In this article, we revisit the evidence for alterations in neuronal proteins in the blood and cerebrospinal fluid associated with epilepsy with and without neurodegenerative diseases. We discuss shared and distinctive characteristics of changes in neuronal markers, review their neurobiological mechanisms, and consider the emerging opportunities and challenges for their future research and diagnostic use.

Brain-derived neurotrophic factor (BDNF) in perinatal depression: Side show or pivotal factor?

Perinatal depression is the most common psychiatric complication of pregnancy, with its detrimental effects on maternal and infant health widely underrated. There is a pressing need for specific molecular biomarkers, with pregnancy-related decline in brain-derived neurotrophic factor (BDNF) in the blood and downregulation of TrkB receptor in the brain reported in clinical and preclinical studies. In this review, we explore the emerging role of BDNF in reproductive biology and discuss evidence suggesting its deficiency as a risk factor for perinatal depression. With the increasing evidence for restoration of serum BDNF levels by antidepressant therapy, the strengthening association of perinatal depression with deficiency of BDNF supports its potential as a surrogate endpoint for preclinical and clinical studies.

Autism-associated CHD8 keeps proliferation of human neural progenitors in check by lengthening the G1 phase of the cell cycle

De novo mutations (DNMs) in chromodomain helicase DNA binding protein 8 (CHD8) are associated with a specific subtype of autism characterized by enlarged heads and distinct cranial features. The vast majority of these DNMs are heterozygous loss-of-function mutations with high penetrance for autism. CHD8 is a chromatin remodeler that preferentially regulates expression of genes implicated in early development of the cerebral cortex. How CHD8 haploinsufficiency alters the normal developmental trajectory of the brain is poorly understood and debated. Using long-term single-cell imaging, we show that disruption of a single copy of CHD8 in human neural precursor cells (NPCs) markedly shortens the G1 phase of the cell cycle. Consistent with faster progression of CHD8+/− NPCs through G1 and the G1/S checkpoint, we observed increased expression of E cyclins and elevated phosphorylation of Erk in these mutant cells – two central signaling pathways involved in S phase entry. Thus, CHD8 keeps proliferation of NPCs in check by lengthening G1, and mono-allelic disruption of this gene alters cell-cycle timing in a way that favors self-renewing over neurogenic cell divisions. Our findings further predict enlargement of the neural progenitor pool in CHD8+/− developing brains, providing a mechanistic basis for macrocephaly in this autism subtype.

Bioprinting and Preliminary Testing of Highly Reproducible Novel Bioink for Potential Skin Regeneration

Three-dimensional (3D) bioprinting is considered as a novel approach in biofabricating cell-laden constructs that could potentially be used to promote skin regeneration following injury. In this study, a novel crosslinked chitosan (CH)–genipin (GE) bioink laden with keratinocyte and human dermal fibroblast cells was developed and printed successfully using an extruder-based bioprinter. By altering the composition and degree of CH–GE crosslinking, bioink printability was further assessed and compared with a commercial bioink. Rheological analysis showed that the viscosity of the optimised bioink was in a suitable range that facilitated reproducible and reliable printing by applying low pressures ranging from 20–40 kPa. The application of low printing pressures proved vital for viability of cells loaded within the bioinks. Further characterisation using MTT assay showed that cells were still viable within the printed construct at 93% despite the crosslinking, processing and after subjecting to physiological conditions for seven days. The morphological study of the printed cells showed that they were mobile within the bioink. Furthermore, the multi-layered 3D printed constructs demonstrated excellent self-supportive structures in a consistent manner.

Stripe rust and leaf rust resistance QTL mapping, epistatic interactions, and co-localization with stem rust resistance loci in spring wheat evaluated over three continents

In wheat, advantageous gene-rich or pleiotropic regions for stripe, leaf, and stem rust and epistatic interactions between rust resistance loci should be accounted for in plant breeding strategies. Leaf rust (Puccinia triticina Eriks.) and stripe rust (Puccinia striiformis f. tritici Eriks) contribute to major production losses in many regions worldwide. The objectives of this research were to identify and study epistatic interactions of quantitative trait loci (QTL) for stripe and leaf rust resistance in a doubled haploid (DH) population derived from the cross of Canadian wheat cultivars, AC Cadillac and Carberry. The relationship of leaf and stripe rust resistance QTL that co-located with stem rust resistance QTL previously mapped in this population was also investigated. The Carberry/AC Cadillac population was genotyped with DArT(®) and simple sequence repeat markers. The parents and population were phenotyped for stripe rust severity and infection response in field rust nurseries in Kenya (Njoro), Canada (Swift Current), and New Zealand (Lincoln); and for leaf rust severity and infection response in field nurseries in Canada (Swift Current) and New Zealand (Lincoln). AC Cadillac was a source of stripe rust resistance QTL on chromosomes 2A, 2B, 3A, 3B, 5B, and 7B; and Carberry was a source of resistance on chromosomes 2B, 4B, and 7A. AC Cadillac contributed QTL for resistance to leaf rust on chromosome 2A and Carberry contributed QTL on chromosomes 2B and 4B. Stripe rust resistance QTL co-localized with previously reported stem rust resistance QTL on 2B, 3B, and 7B, while leaf rust resistance QTL co-localized with 4B stem rust resistance QTL. Several epistatic interactions were identified both for stripe and leaf rust resistance QTL. We have identified useful combinations of genetic loci with main and epistatic effects. Multiple disease resistance regions identified on chromosomes 2A, 2B, 3B, 4B, 5B, and 7B are prime candidates for further investigation and validation of their broad resistance.

The Pontin series of recombinant alien translocations in bread wheat: single translocations integrating combinations of Bdv2, Lr19 and Sr25 disease-resistance genes from Thinopyrum intermedium and Th. ponticum

Two bread wheat lines each with a translocation on chromosome 7DL from either Thinopyrum intermedium (TC5 and TC14) or Thinopyrum ponticum (T4m), were hybridized in a ph1b mutant background to enhance recombination between the two translocated chromosomal segments. The frequency of recombinants was high in lines derived from the larger and similar-sized translocations (TC5/T4m), but much lower when derived from different-sized translocations (TC14/T4m). Recombinant translocations contained combinations of resistance genes Bdv2, Lr19 and Sr25 conferring resistance to Barley yellow dwarf virus (BYDV), leaf rust and stem rust, respectively. Their genetic composition was identified using bioassays and molecular markers specific for the two progenitor Thinopyrum species. This set of 7DL Th. ponticum/intermedium recombinant translocations was termed the Pontin series. In addition to Thinopyrum markers, the size of the translocation was estimated with the aid of wheat markers mapped on each of the 7DL deletion bins. Bioassays for BYDV, leaf rust and stem rust were performed under greenhouse and field conditions. Once separated from ph1b background, the Pontin recombinant translocations were stable and showed normal inheritance in successive backcrosses. The reported Pontin translocations integrate important resistance genes in a single linkage block which will allow simultaneous selection of disease resistance. Combinations of Bdv2 + Lr19 or Lr19 + Sr25 in both long and short translocations, are available to date. The smaller Pontins, comprising only 20 % of the distal portion of 7DL, will be most attractive to breeders.

Is evidence for late selection due to automatic or attentional processing of stimulus identities?

This study determined whether evidence for late selection is due to attention processing or to processing by an automatic system that is separate from attention (two systems framework; Eriksen, Webb, & Fournier, 1990). The task was a two-choice discrimination of a target that appeared in one of two sequentially cued locations in an eight-letter visual display. Attention was directed to the first cued location (cue 1), and whether identification processing occurred at a different location before the second cue (cue 2) directed attention there was determined. Cue validity varied across two experiments, and critical trials were those in which the target appeared at cue 2. For these trials, the target was preceded by a letter (either identical, neutral, or incompatible) that changed to the target at various time intervals following cue 2. Automatic identification was assumed if the incompatible letter interfered with response to the target when it appeared only before cue 2 onset and independent of cue validity. The incompatible letter appearing only before cue 2 onset interfered with the target when the target occurred equally often at cue 1 and cue 2, but not when the target occurred at cue 1 70% and at cue 2 30% of the time. This disconfirms the two systems framework and suggests that attention is required for spatial form processing and response competition.

The stereoscopic (cyclopean) motion aftereffect is dependent upon the temporal frequency of adapting motion

This study investigated whether the stereoscopic (cyclopean) motion aftereffect (induced by adaptation to moving binocular disparity information) is dependent upon the temporal frequency or speed of adapting motion. The stereoscopic stimuli were gratings created from disparity embedded in a dynamic random-dot stereogram. Across different combinations of stereoscopic spatial frequency, temporal frequency and speed of adapting motion, the duration of the aftereffect was dependent upon temporal frequency (maximal aftereffect=1-2 cyc s(-1)). These results support the idea that stereoscopic motion is processed by a cortical mechanism that computes cyclopean motion energy.

Exposure duration affects the perceived direction of cyclopean type II plaids

This study investigated the effect of exposure duration on the perceived direction of cyclopean Type I and Type II plaids moving in the X/Y plane. The cyclopean plaids were created from grating components defined by binocular disparity embedded in a dynamic random-dot stereogram. The results showed that the cyclopean Type I plaid appeared to move in the intersection-of-constraints (IOC) direction across the range of exposures tested. However, the cyclopean Type II plaids appeared to move in a direction different from the IOC with short exposures but near the IOC with long exposures. This perceived directional shift was also obtained with luminance-defined Type II plaids. A common pattern-motion mechanism that processes cyclopean and luminance motion signals appears responsible for the perceived directional shift of the Type II plaids.

Cross-domain adaptation reveals that a common mechanism computes stereoscopic (cyclopean) and luminance plaid motion

Across three experiments, this study investigated the visual processing of moving stereoscopic plaid patterns (plaids created with cyclopean components defined by moving binocular disparity embedded in a dynamic random-dot stereogram). Results showed that adaptation to a moving stereoscopic plaid or its components affected the perceived coherence of a luminance test plaid, and vice versa. Cross-domain adaptation suggests that stereoscopic and luminance motion signals feed into a common pattern-motion mechanism, consistent with the idea that stereoscopic motion signals are computed early in the motion processing stream.

The stereoscopic (cyclopean) motion aftereffect is selective for spatial frequency and orientation of disparity modulation

Across two experiments, this study investigated the spatial frequency tuning and orientation tuning (both in the disparity domain) of the stereoscopic (cyclopean) motion aftereffect. In Experiment 1, observers adapted to a moving stereoscopic grating of a given cyclopean spatial frequency and tested for the motion aftereffect with a static grating of the same or different spatial frequency. Robust motion aftereffects were induced only when the spatial frequency of the adapt and test stimuli was the same. In Experiment 2, observers adapted to a moving stereoscopic grating of a given cyclopean orientation and tested for the motion aftereffect with a static grating of the same or different orientation. Robust motion aftereffects were induced only when the orientation of the adapt and test stimuli was the same. Together, these results suggest that the stereoscopic motion aftereffect is tuned for cyclopean spatial frequency and orientation which, in turn, suggest that the stereoscopic motion aftereffect is mediated by low-level oriented spatial-frequency mechanisms.

Occlusion contributes to temporal processing differences between crossed and uncrossed stereopsis in random-dot displays

Stereoscopic depth discrimination was investigated in crossed and uncrossed directions using stimuli defined by binocular disparity differences embedded in dynamic random-dot stereograms. Across three experiments, fixation was directed to a point on the display screen (which placed crossed stimuli in front of and uncrossed stimuli behind, the background dots of the stereogram), to a point in front of the display screen (which placed both crossed and uncrossed stimuli in front of the background dots), and to a point behind the display screen (which placed both crossed and uncrossed stimuli behind the background dots). Results showed that depth discrimination was always good when the stimuli appeared in front of the background dots of the stereogram, whereas discrimination was always poor when the stimuli appeared behind the background dots. These results suggest that differences between crossed and uncrossed stereopsis as reported in past research arose, in part, from effects related to occlusion.

HLA-G isoforms produced by placental cytotrophoblasts and found in amniotic fluid are due to unusual glycosylation

The human placenta expresses HLA-G, a nonclassical (class Ib) MHC molecule that could play a central role in maternal tolerance of the semiallogeneic fetus. In this work, we report the production of a new mAb, 4H84, that specifically reacts with HLA-G in two formats: immunocytochemistry and immunoblotting. Immunolocalization experiments with 4H84 confirmed our previous finding that cytotrophoblasts within the uterine wall are the only cells in tissue sections of placenta that express the HLA-G protein. Additional experiments showed that both amniocytes and cytotrophoblasts in the amnion-chorion express this protein. Since multiple HLA-G transcripts have been described, we used immunoblotting to study the HLA-G isoforms produced by cytotrophoblasts in vitro and by the amnion-chorion in vivo. Cytotrophoblasts, their conditioned medium, and amniotic fluid samples contained heterodisperse immunoreactive bands (Mr 35,000-50,000). N-deglycosylation by peptide-N-glycosidase F digestion resolved these isoforms into two distinct bands. Cell samples contained primarily an Mr 37,000-42,000 protein, most likely encoded by the full-length mRNA. Conditioned medium and amniotic fluid contained a slightly smaller protein, most likely the secreted form lacking the transmembrane and cytoplasmic regions. Removal of polylactosamine chains by endo-beta D-galactosidase digestion significantly reduced the electrophoretic mobility of the immunoreactive bands, suggesting that HLA-G, unlike class Ib molecules studied to date, carries N-acetyllactosamine units. These data show that Mr heterogeneity of HLA-G is due to its novel glycosylation, rather than to the translation of alternatively spliced mRNAs. We postulate that the unusual carbohydrate structures this molecule carries could interact with maternal immune cells and/or stabilize the molecule.

Localization of tumour necrosis factor production in cells at the materno/fetal interface in human pregnancy

Biologically active tumour necrosis factor (TNF) was detected in medium conditioned by incubation with explants of human pregnancy decidua or fetal chorionic villous tissue, taken in the first trimester and at term. Addition of endotoxin increased TNF release in most cases. ELISA assays gave similar results for TNF-alpha and also demonstrated low levels of TNF-beta. Using cell populations purified by flow cytometry, secretion of biologically active TNF was shown to be localized to the macrophages. Cytotrophoblast purified from term amniochorion produced no TNF. Both decidual and chorionic villous tissue at term contained mRNA for TNF-alpha and TNF-beta. TNF-alpha mRNA was confined to decidual macrophages in first trimester tissue, and was not present in chorionic cytotrophoblast. TNF-beta mRNA, in contrast, was detected in both macrophage and non-macrophage populations in term decidua.

First year of AIDS services delivery under Title I of the Ryan White CARE Act

This is a review of (a) the emergency assistance for ambulatory HIV medical and support services provided in the first year by eligible metropolitan areas (EMAs) funded under Title I of the Ryan White Comprehensive AIDS Resources Emergency (CARE) Act of 1990, (b) the varied responses and processes by which the 16 urban areas receiving Title I funds in 1991 met legislative mandates, (c) the central nature of planning councils under Title I and their formation and functioning, and (d) issues related to current implementation and future expansion of Title I to additional eligible metropolitan areas. Integral to the review is a brief discussion of the history of AIDS and HIV infection, particularly in cities receiving CARE Act funding, an overview of Title I requirements, and a description of the organizational structures cities are using to implement Title I. Information on Title I EMAs is based on analysis of their 1991 applications, bylaws of their HIV service planning councils, intergovernmental agreements between Title I cities and other political entities, and contracts executed by Title I grantees with providers for the delivery of services. Interviews with personnel in several Title I EMAs, including planning council members and grantee staff members, provided additional information. This is the first descriptive accounting of activities related to the 1991 applications for and uses of Title I funds, and the administrative and service issues related to this process.