-
European Neuropsychopharmacology : the... Jul 2024Clozapine is the only approved antipsychotic for treatment-resistant schizophrenia (TRS). Although a large body of evidence supports its efficacy and favorable... (Review)
Review
Overcoming the barriers to identifying and managing treatment-resistant schizophrenia and to improving access to clozapine: A narrative review and recommendation for clinical practice.
Clozapine is the only approved antipsychotic for treatment-resistant schizophrenia (TRS). Although a large body of evidence supports its efficacy and favorable risk-benefit ratio in individuals who have failed two or more antipsychotics, clozapine remains underused. However, variations in clozapine utilization across geographic and clinical settings suggest that it could be possible to improve its use. In this narrative review and expert opinion, we summarized information available in the literature on the mechanisms of action, effectiveness, and potential adverse events of clozapine. We identified barriers leading to discouragement in clozapine prescription internationally, and we proposed practical solutions to overcome each barrier. One of the main obstacles identified to the use of clozapine is the lack of appropriate training for physicians: we highlighted the need to develop specific professional programs to train clinicians, both practicing and in residency, on the relevance and efficacy of clozapine in TRS treatment, initiation, maintenance, and management of potential adverse events. This approach would facilitate physicians to identify eligible patients and offer clozapine as a treatment option in the early stage of the disease. We also noted that increasing awareness of the benefits of clozapine among healthcare professionals, people with TRS, and their caregivers can help promote the use of clozapine. Educational material, such as leaflets or videos, could be developed and distributed to achieve this goal. The information provided in this article may be useful to improve disease burden and support healthcare professionals, patients, and caregivers navigating the complex pathways to TRS management.
Topics: Humans; Clozapine; Antipsychotic Agents; Schizophrenia, Treatment-Resistant; Health Services Accessibility; Schizophrenia
PubMed: 38657339
DOI: 10.1016/j.euroneuro.2024.04.012 -
Genetics Apr 2024The accurate segregation of homologous chromosomes during the Meiosis I reductional division in most sexually reproducing eukaryotes requires crossing over between...
The accurate segregation of homologous chromosomes during the Meiosis I reductional division in most sexually reproducing eukaryotes requires crossing over between homologs. In baker's yeast approximately 80 percent of meiotic crossovers result from Mlh1-Mlh3 and Exo1 acting to resolve double-Holliday junction (dHJ) intermediates in a biased manner. Little is known about how Mlh1-Mlh3 is recruited to recombination intermediates to perform its role in crossover resolution. We performed a gene dosage screen in baker's yeast to identify novel genetic interactors with Mlh1-Mlh3. Specifically, we looked for genes whose lowered dosage reduced meiotic crossing over using sensitized mlh3 alleles that disrupt the stability of the Mlh1-Mlh3 complex and confer defects in mismatch repair but do not disrupt meiotic crossing over. To our surprise we identified genetic interactions between MLH3 and DMC1, the recombinase responsible for recombination between homologous chromosomes during meiosis. We then showed that Mlh3 physically interacts with Dmc1 in vitro and in vivo. Partial complementation of Mlh3 crossover functions was observed when MLH3 was expressed under the control of the CLB1 promoter (NDT80 regulon), suggesting that Mlh3 function can be provided late in meiotic prophase at some functional cost. A model for how Dmc1 could facilitate Mlh1-Mlh3's role in crossover resolution is presented.
PubMed: 38657110
DOI: 10.1093/genetics/iyae066 -
Cellular and Molecular Life Sciences :... Apr 2024Sex chromosome aneuploidies are among the most common variations in human whole chromosome copy numbers, with an estimated prevalence in the general population of 1:400... (Review)
Review
Sex chromosome aneuploidies are among the most common variations in human whole chromosome copy numbers, with an estimated prevalence in the general population of 1:400 to 1:1400 live births. Unlike whole-chromosome aneuploidies of autosomes, those of sex chromosomes, such as the 47, XXY aneuploidy that causes Klinefelter Syndrome (KS), often originate from the paternal side, caused by a lack of crossover (CO) formation between the X and Y chromosomes. COs must form between all chromosome pairs to pass meiotic checkpoints and are the product of meiotic recombination that occurs between homologous sequences of parental chromosomes. Recombination between male sex chromosomes is more challenging compared to both autosomes and sex chromosomes in females, as it is restricted within a short region of homology between X and Y, called the pseudo-autosomal region (PAR). However, in normal individuals, CO formation occurs in PAR with a higher frequency than in any other region, indicating the presence of mechanisms that promote the initiation and processing of recombination in each meiotic division. In recent years, research has made great strides in identifying genes and mechanisms that facilitate CO formation in the PAR. Here, we outline the most recent and relevant findings in this field. XY chromosome aneuploidy in humans has broad-reaching effects, contributing significantly also to Turner syndrome, spontaneous abortions, oligospermia, and even infertility. Thus, in the years to come, the identification of genes and mechanisms beyond XY aneuploidy is expected to have an impact on the genetic counseling of a wide number of families and adults affected by these disorders.
Topics: Humans; Animals; Chromosome Pairing; Male; Meiosis; Mice; Chromosome Segregation; Female; Aneuploidy; Chromosomes, Human, X; Chromosomes, Human, Y; Sex Chromosomes; Crossing Over, Genetic
PubMed: 38653846
DOI: 10.1007/s00018-024-05216-0 -
BioRxiv : the Preprint Server For... Mar 2024A central basic feature of meiosis is pairing of homologous maternal and paternal chromosomes ("homologs") intimately along their lengths. Recognition between homologs...
A central basic feature of meiosis is pairing of homologous maternal and paternal chromosomes ("homologs") intimately along their lengths. Recognition between homologs and their juxtaposition in space are mediated by axis-associated DNA recombination complexes. Additional effects ensure that pairing occurs without ultimately giving entanglements among unrelated chromosomes. Here we examine the process of homolog juxtaposition in real time by 4D fluorescence imaging of tagged chromosomal loci at high spatio-temporal resolution in budding yeast. We discover that corresponding loci start coming together from a quite large distance (∼1.8 µm) and progress to completion of pairing in a very short time, usually less than six minutes (thus, "rapid homolog juxtaposition" or "RHJ"). Juxtaposition initiates by motion-mediated extension of a nascent interhomolog DNA linkage, raising the possibility of a tension-mediated trigger. In a first transition, homolog loci move rapidly together (in ∼30 sec, at speeds of up to ∼60 nm/sec) into a discrete intermediate state corresponding to canonical ∼400 nm axis distance coalignment. Then, after a short pause, crossover/noncrossover differentiation (crossover interference) mediates a second short, rapid transition that brings homologs even closer together. If synaptonemal complex (SC) component Zip1 is present, this transition concomitantly gives final close pairing by axis juxtaposition at ∼100 nm, the "SC distance". We also find that: (i) RHJ occurs after chromosomes acquire their prophase chromosome organization; (ii) is nearly synchronously over thirds (or more) of chromosome lengths; but (iii) is asynchronous throughout the genome. Furthermore, cytoskeleton-mediated movement is important for the timing and distance of RHJ onset and also for ensuring normal progression. Potential implications for local and global aspects of pairing are discussed.
PubMed: 38586034
DOI: 10.1101/2024.03.23.586418 -
Schizophrenia Research May 2024
Topics: Humans; Schizophrenia; Psychiatric Status Rating Scales; Data Accuracy; Data Interpretation, Statistical; Antipsychotic Agents
PubMed: 38581826
DOI: 10.1016/j.schres.2024.03.052 -
Nature Communications Apr 2024Programmed DNA double-strand break (DSB) formation is a crucial feature of meiosis in most organisms. DSBs initiate recombination-mediated linking of homologous...
Programmed DNA double-strand break (DSB) formation is a crucial feature of meiosis in most organisms. DSBs initiate recombination-mediated linking of homologous chromosomes, which enables correct chromosome segregation in meiosis. DSBs are generated on chromosome axes by heterooligomeric focal clusters of DSB-factors. Whereas DNA-driven protein condensation is thought to assemble the DSB-machinery, its targeting to chromosome axes is poorly understood. We uncover in mice that efficient biogenesis of DSB-machinery clusters requires seeding by axial IHO1 platforms. Both IHO1 phosphorylation and formation of axial IHO1 platforms are diminished by chemical inhibition of DBF4-dependent kinase (DDK), suggesting that DDK contributes to the control of the axial DSB-machinery. Furthermore, we show that axial IHO1 platforms are based on an interaction between IHO1 and the chromosomal axis component HORMAD1. IHO1-HORMAD1-mediated seeding of the DSB-machinery on axes ensures sufficiency of DSBs for efficient pairing of homologous chromosomes. Without IHO1-HORMAD1 interaction, residual DSBs depend on ANKRD31, which enhances both the seeding and the growth of DSB-machinery clusters. Thus, recombination initiation is ensured by complementary pathways that differentially support seeding and growth of DSB-machinery clusters, thereby synergistically enabling DSB-machinery condensation on chromosomal axes.
Topics: Mice; Animals; Cell Cycle Proteins; DNA Breaks, Double-Stranded; DNA; Meiosis; Synaptonemal Complex; Recombination, Genetic; Homologous Recombination
PubMed: 38580643
DOI: 10.1038/s41467-024-47020-1 -
Neuropsychiatric Disease and Treatment 2024HP-3070, a once-daily asenapine transdermal system, is the first antipsychotic "patch" formulation FDA approved for adults with schizophrenia. Positive and Negative... (Clinical Trial)
Clinical Trial
INTRODUCTION
HP-3070, a once-daily asenapine transdermal system, is the first antipsychotic "patch" formulation FDA approved for adults with schizophrenia. Positive and Negative Syndrome Scale (PANSS) score items can be grouped into a five-factor structure to describe specific schizophrenia symptom domains. This post hoc analysis of data from a pivotal study evaluated HP-3070's efficacy by examining these factors.
METHODS
In a phase 3 study, adults with an acute exacerbation of schizophrenia were randomized to six weeks of treatment with HP-3070 3.8mg/24h, 7.6mg/24h, or placebo. An analysis was performed using the five PANSS factor domains (negative symptoms, positive symptoms, disorganized thought, uncontrolled hostility/excitement, anxiety/depression). Mixed-model repeated-measures (MMRM) analysis included change from baseline (CFB) in PANSS factor score as the repeated dependent variable, with country, treatment, visit, treatment by visit interaction, and baseline PANSS score as covariates.
RESULTS
The analysis included 607 patients. Treatment with HP-3070 3.8mg/24h resulted in a statistically significant LS mean CFB (improvement) vs placebo at Weeks 4-6 for all domains except for anxiety/depression, where a numerical difference was observed in favor of active treatments. Among the domains, the positive symptom factor demonstrated the numerically greatest LS mean (SE) difference from placebo in CFB, which for HP-3070 7.6mg/24h was -2.0 [0.57] and for HP-3070 3.8mg/24h was -2.3 [0.57]; <0.001 for both. Treatment effect size for the positive symptom factor using Cohen's (95% confidence intervals) was 0.39 (0.17, 0.61) for HP-3070 7.6mg/24h and 0.45 (0.20, 0.64) for HP-3070 3.8mg/24h.
DISCUSSION
Post hoc analysis using a PANSS five-factor model suggests that HP-3070 may address a broad range of symptoms in people with schizophrenia.
PubMed: 38566884
DOI: 10.2147/NDT.S439712 -
European Neuropsychopharmacology : the... Jun 2024
Topics: Diagnostic and Statistical Manual of Mental Disorders; History, 20th Century; Humans; History, 21st Century
PubMed: 38547544
DOI: 10.1016/j.euroneuro.2024.03.001 -
The Plant Journal : For Cell and... Jun 2024The sugarcane (Saccharum spp.) genome is one of the most complex of all. Modern varieties are highly polyploid and aneuploid as a result of hybridization between...
The sugarcane (Saccharum spp.) genome is one of the most complex of all. Modern varieties are highly polyploid and aneuploid as a result of hybridization between Saccharum officinarum and S. spontaneum. Little research has been done on meiotic control in polyploid species, with the exception of the wheat Ph1 locus harboring the ZIP4 gene (TaZIP4-B2) which promotes pairing between homologous chromosomes while suppressing crossover between homeologs. In sugarcane, despite its interspecific origin, bivalent association is favored, and multivalents, if any, are resolved at the end of prophase I. Thus, our aim herein was to investigate the purported genetic control of meiosis in the parental species and in sugarcane itself. We investigated the ZIP4 gene and immunolocalized meiotic proteins, namely synaptonemal complex proteins Zyp1 and Asy1. The sugarcane ZIP4 gene is located on chromosome 2 and expressed more abundantly in flowers, a similar profile to that found for TaZIP4-B2. ZIP4 expression is higher in S. spontaneum a neoautopolyploid, with lower expression in S. officinarum, a stable octoploid species. The sugarcane Zip4 protein contains a TPR domain, essential for scaffolding. Its 3D structure was also predicted, and it was found to be very similar to that of TaZIP4-B2, reflecting their functional relatedness. Immunolocalization of the Asy1 and Zyp1 proteins revealed that S. officinarum completes synapsis. However, in S. spontaneum and SP80-3280 (a modern variety), no nuclei with complete synapsis were observed. Importantly, our results have implications for sugarcane cytogenetics, genetic mapping, and genomics.
Topics: Saccharum; Meiosis; Plant Proteins; Chromosomes, Plant; Polyploidy; Gene Expression Regulation, Plant; Synaptonemal Complex
PubMed: 38523577
DOI: 10.1111/tpj.16731 -
Nucleic Acids Research Jun 2024N-terminal arginine (NTR) methylation is a conserved feature of PIWI proteins, which are central components of the PIWI-interacting RNA (piRNA) pathway. The significance...
N-terminal arginine (NTR) methylation is a conserved feature of PIWI proteins, which are central components of the PIWI-interacting RNA (piRNA) pathway. The significance and precise function of PIWI NTR methylation in mammals remains unknown. In mice, PIWI NTRs bind Tudor domain containing proteins (TDRDs) that have essential roles in piRNA biogenesis and the formation of the chromatoid body. Using mouse MIWI (PIWIL1) as paradigm, we demonstrate that the NTRs are essential for spermatogenesis through the regulation of transposons and gene expression. The loss of TDRD5 and TDRKH interaction with MIWI results in attenuation of piRNA amplification. We find that piRNA amplification is necessary for transposon control and for sustaining piRNA levels including select, nonconserved, pachytene piRNAs that target specific mRNAs required for spermatogenesis. Our findings support the notion that the vast majority of pachytene piRNAs are dispensable, acting as self-serving genetic elements that rely for propagation on MIWI piRNA amplification. MIWI-NTRs also mediate interactions with TDRD6 that are necessary for chromatoid body compaction. Furthermore, MIWI-NTRs promote stabilization of spermiogenic transcripts that drive nuclear compaction, which is essential for sperm formation. In summary, the NTRs underpin the diversification of MIWI protein function.
Topics: Animals; Male; Mice; Arginine; Argonaute Proteins; DNA Transposable Elements; Pachytene Stage; Piwi-Interacting RNA; RNA, Small Interfering; RNA-Binding Proteins; Spermatogenesis; Tudor Domain
PubMed: 38520410
DOI: 10.1093/nar/gkae193