Loss of the neural-specific BAF subunit ACTL6B relieves repression of early response genes and causes recessive autism.

Synaptic activity in neurons leads to the rapid activation of genes involved in mammalian behavior. ATP-dependent chromatin remodelers such as the BAF complex contribute to these responses and are generally thought to activate transcription. However, the mechanisms keeping such "early activation" genes silent have been a mystery. In the course of investigating Mendelian recessive autism, we identified six families with segregating loss-of-function mutations in the neuronal BAF (nBAF) subunit ACTL6B (originally named BAF53b). Accordingly, ACTL6B was the most significantly mutated gene in the Simons Recessive Autism Cohort. At least 14 subunits of the nBAF complex are mutated in autism, collectively making it a major contributor to autism spectrum disorder (ASD). Patient mutations destabilized ACTL6B protein in neurons and rerouted dendrites to the wrong glomerulus in the fly olfactory system. Humans and mice lacking ACTL6B showed corpus callosum hypoplasia, indicating a conserved role for ACTL6B in facilitating neural connectivity. Actl6b knockout mice on two genetic backgrounds exhibited ASD-related behaviors, including social and memory impairments, repetitive behaviors, and hyperactivity. Surprisingly, mutation of Actl6b relieved repression of early response genes including AP1 transcription factors (Fos, Fosl2, Fosb, and Junb), increased chromatin accessibility at AP1 binding sites, and transcriptional changes in late response genes associated with early response transcription factor activity. ACTL6B loss is thus an important cause of recessive ASD, with impaired neuron-specific chromatin repression indicated as a potential mechanism.

Gap junction adhesion is necessary for radial migration in the neocortex.

Radial glia, the neuronal stem cells of the embryonic cerebral cortex, reside deep within the developing brain and extend radial fibres to the pial surface, along which embryonic neurons migrate to reach the cortical plate. Here we show that the gap junction subunits connexin 26 (Cx26) and connexin 43 (Cx43) are expressed at the contact points between radial fibres and migrating neurons, and acute downregulation of Cx26 or Cx43 impairs the migration of neurons to the cortical plate. Unexpectedly, gap junctions do not mediate neuronal migration by acting in the classical manner to provide an aqueous channel for cell-cell communication. Instead, gap junctions provide dynamic adhesive contacts that interact with the internal cytoskeleton to enable leading process stabilization along radial fibres as well as the subsequent translocation of the nucleus. These results indicate that gap junction adhesions are necessary for glial-guided neuronal migration, raising the possibility that the adhesive properties of gap junctions may have an important role in other physiological processes and diseases associated with gap junction function.

The role of SAP97 in synaptic glutamate receptor dynamics.

Proteins of the PSD-95-like membrane-associated guanylate kinase (PSD-MAGUK) family are vital for trafficking AMPA receptors (AMPARs) to synapses, a process necessary for both basal synaptic transmission and forms of synaptic plasticity. Synapse-associated protein 97 (SAP97) exhibits protein interactions, such as direct interaction with the GluA1 AMPAR subunit, and subcellular localization (synaptic, perisynaptic, and dendritic) unique within this protein family. Due in part to the lethality of the germline knockout of SAP97, this protein's role in synaptic transmission and plasticity is poorly understood. We found that overexpression of SAP97 during early development traffics AMPARs and NMDA receptors (NMDARs) to synapses, and that SAP97 rescues the deficits in AMPAR currents normally seen in PSD-93/-95 double-knockout neurons. Mature neurons that have experienced the overexpression of SAP97 throughout development exhibit enhanced AMPAR and NMDAR currents, as well as faster NMDAR current decay kinetics. In loss-of-function experiments using conditional SAP97 gene deletion, we recorded no deficits in glutamatergic transmission or long-term potentiation. These results support the hypothesis that SAP97 is part of the machinery that traffics glutamate receptors and compensates for other PSD-MAGUKs in knockout mouse models. However, due to functional redundancy, other PSD-MAGUKs can presumably compensate when SAP97 is conditionally deleted during development.

Missing scheduled visits in the outpatient clinic as a marker of short-term admissions and death.

INTRODUCTION: It is not uncommon for patients with HIV infection to miss scheduled visits in outpatient clinics without justifying the failure to appear or reschedule the appointment. Few studies have assessed the impact of inconsistent follow-ups on resource use and disease outcomes in this patient population. OBJECTIVE: To assess the effect of missing scheduled visits to the outpatient clinic on the health outcomes of HIV-infected patients. METHODS: Between January and June 2006, we conducted a prospective observational study monitoring assistance at an outpatient HIV/AIDS clinic of a tertiary hospital within a public health care system in a developed country. The short-term subsequent events (deaths and admissions) of the population were observed from January to December 2006. RESULTS: Of the 1,733 HIV patients who were scheduled in the outpatient clinic, 103 met the criteria of missing scheduled visit (5.9%). Hospital admissions and mortality rates were significantly higher in the missing scheduled visit group compared to non-missing scheduled visits (27.2% vs 8.9%; P < .001 and 5.8% vs 0.7%; P < .001, respectively). Patients with missing scheduled visits had a higher risk of hospital admissions (odds ratio [OR] 2.4; 95% CI, 1.4-4) and mortality (OR 6.7; 95% CI, 2.2-18.5) adjusted by age, CD4 cell count, HIV stage, and category of transmission. CONCLUSIONS: Missing scheduled visits was an independent predicting factor for hospital admission and mortality. It is warranted to monitor and implement resources to reduce missed appointments.

Vesicular monoamine and glutamate transporters select distinct synaptic vesicle recycling pathways.

Previous work has characterized the properties of neurotransmitter release at excitatory and inhibitory synapses, but we know remarkably little about the properties of monoamine release, because these neuromodulators do not generally produce a fast ionotropic response. Since dopamine and serotonin neurons can also release glutamate in vitro and in vivo, we have used the vesicular monoamine transporter VMAT2 and the vesicular glutamate transporter VGLUT1 to compare the localization and recycling of synaptic vesicles that store, respectively, monoamines and glutamate. First, VMAT2 segregates partially from VGLUT1 in the boutons of midbrain dopamine neurons, indicating the potential for distinct release sites. Second, endocytosis after stimulation is slower for VMAT2 than VGLUT1. During the stimulus, however, the endocytosis of VMAT2 (but not VGLUT1) accelerates dramatically in midbrain dopamine but not hippocampal neurons, indicating a novel, cell-specific mechanism to sustain high rates of release. On the other hand, we find that in both midbrain dopamine and hippocampal neurons, a substantially smaller proportion of VMAT2 than VGLUT1 is available for evoked release, and VMAT2 shows considerably more dispersion along the axon after exocytosis than VGLUT1. Even when expressed in the same neuron, the two vesicular transporters thus target to distinct populations of synaptic vesicles, presumably due to their selection of distinct recycling pathways.

Connexin 43 mediates the tangential to radial migratory switch in ventrally derived cortical interneurons.

The adult cerebral cortex is composed of excitatory and inhibitory neurons that arise from progenitor cells in disparate proliferative regions in the developing brain and follow different migratory paths. Excitatory pyramidal neurons originate near the ventricle and migrate radially to their position in the cortical plate along radial glial fibers. On the other hand, inhibitory interneurons arise in the ventral telencephalon and migrate tangentially to enter the developing cortex before migrating radially to reach their correct laminar position. Gap junction adhesion has been shown to play an important mechanistic role in the radial migration of excitatory neurons. We asked whether a similar mechanism governs the tangential or radial migration of inhibitory interneurons. Using short hairpin RNA knockdown of Connexin 43 (Cx43) and Cx26 together with rescue experiments, we found that gap junctions are dispensable for the tangential migration of interneurons, but that Cx43 plays a role in the switch from tangential to radial migration that allows interneurons to enter the cortical plate and find their correct laminar position. Moreover this action is dependent on the adhesive properties and the C terminus of Cx43 but not the Cx43 channel. Thus, the radial phase of interneuron migration resembles that of excitatory neuron migration in terms of dependence on Cx43 adhesion. Furthermore, gap junctions between migrating interneurons and radial processes were observed by electron microscopy. These findings provide mechanistic and structural support for a gap junction-mediated interaction between migrating interneurons and radial glia during the switch from tangential to radial migration.

Criterion validity of MMPI-3 scores in preemployment evaluations of public safety candidates.

The present study evaluated the criterion validity and practical utility of Minnesota Multiphasic Personality Inventory-3 (MMPI-3) scores in preemployment evaluations of police candidates (n = 377) and candidates for other public safety occupations (n = 276) in the Midwestern United States. Preemployment psychological reports were used to rate problems in the ten California Commission on Peace Officer Standards and Training screening dimensions (POST-10 dimensions). MMPI-3 T score means and standard deviations indicated that substantive scale scores were generally lower and less variable relative to the normative sample. MMPI-3 scores were meaningfully associated with problems in the POST-10 dimensions with similar patterns as past research but with generally larger effect sizes (likely due, in part, to criterion contamination). Relative risk ratio (RRR) findings supported the practical utility of interpretive guidelines described in the MMPI-3 Police Candidate Interpretive Report interpretive manual. Results are discussed in terms of the wider MMPI-2-RF literature in police officer preemployment evaluations. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Gap junctions: multifaceted regulators of embryonic cortical development.

The morphological development of the cerebral cortex from a primitive neuroepithelium into a complex laminar structure underlying higher cognition must rely on a network of intercellular signaling. Gap junctions are widely expressed during embryonic development and provide a means of cell-cell contact and communication. We review the roles of gap junctions in regulating the proliferation of neural progenitors as well as the migration and differentiation of young neurons in the embryonic cerebral cortex. There is substantial evidence that although gap junctions act in the classical manner coupling neural progenitors, they also act as hemichannels mediating the spread of calcium waves across progenitor cell populations and as adhesive molecules aiding neuronal migration. Gap junctions are thus emerging as multifaceted regulators of cortical development playing diverse roles in intercellular communication.

The impact of polymyxin B dosage on in-hospital mortality of patients treated with this antibiotic.

OBJECTIVE: To assess the impact of dosage on in-hospital mortality of patients receiving intravenous polymyxin B. METHODS: A retrospective cohort study was performed from January 2003 to December 2009. Patients ≥ 18 years receiving intravenous polymyxin B for ≥ 72 h were analysed. Clinical covariates were assessed and data were retrieved from medical records. Subgroup analyses were performed in patients with microbiologically confirmed infections and in patients with bacteraemia. Renal toxicity was also assessed. Logistic regression models (LRMs) were performed for the entire cohort and subgroups. RESULTS: A total of 276 patients were included. The overall in-hospital mortality was 60.5% (167 of 276). The final LRM showed that severe sepsis or septic shock [adjusted odds ratio (aOR) 4.07; 95% confidence interval (CI) 2.22-7.46], presence of mechanical ventilation (aOR 3.14; 95% CI 1.73-5.71), Charlson co-morbidity score (aOR 1.25; 95% CI 1.09-1.44) and age (aOR 1.02; 95% CI 1.01-1.04) were independently associated with increased in-hospital mortality, while ≥ 200 mg/day polymyxin B was associated with lower risk for this outcome (aOR 0.43; 95% CI 0.23-0.79). The effect of ≥ 200 mg/day polymyxin B on in-hospital mortality was higher in both subgroups (microbiologically documented infections and bacteraemia). Patients receiving ≥ 200 mg/day of polymyxin B had significantly higher risk of severe renal impairment. CONCLUSION: A dosage of ≥ 200 mg/day polymyxin B was associated with lower in-hospital mortality. The benefit of these higher doses outweighed the risk of severe renal dysfunction during therapy. Large prospective studies including pharmacokinetic/pharmacodynamic analysis are still required to define the best dosage regimens of polymyxin B.

Reduction in incidence of nosocomial methicillin-resistant Staphylococcus aureus (MRSA) infection in an intensive care unit: role of treatment with mupirocin ointment and chlorhexidine baths for nasal carriers of MRSA.

After the introduction of routine treatment for every nasal carrier of methicillin-resistant Staphylococcus aureus, active follow-up surveillance for nosocomial methicillin-resistant S. aureus infection was conducted for 5 years in an intensive care unit of a tertiary-care teaching hospital. There was a significant decrease in the incidence of nosocomial methicillin-resistant S. aureus infection during the later years of follow-up. Decolonization of nasal carriers of methicillin-resistant S. aureus is probably associated with such findings.

Proteomic and bioinformatic analysis of mammalian SWI/SNF complexes identifies extensive roles in human malignancy.

Subunits of mammalian SWI/SNF (mSWI/SNF or BAF) complexes have recently been implicated as tumor suppressors in human malignancies. To understand the full extent of their involvement, we conducted a proteomic analysis of endogenous mSWI/SNF complexes, which identified several new dedicated, stable subunits not found in yeast SWI/SNF complexes, including BCL7A, BCL7B and BCL7C, BCL11A and BCL11B, BRD9 and SS18. Incorporating these new members, we determined mSWI/SNF subunit mutation frequency in exome and whole-genome sequencing studies of primary human tumors. Notably, mSWI/SNF subunits are mutated in 19.6% of all human tumors reported in 44 studies. Our analysis suggests that specific subunits protect against cancer in specific tissues. In addition, mutations affecting more than one subunit, defined here as compound heterozygosity, are prevalent in certain cancers. Our studies demonstrate that mSWI/SNF is the most frequently mutated chromatin-regulatory complex (CRC) in human cancer, exhibiting a broad mutation pattern, similar to that of TP53. Thus, proper functioning of polymorphic BAF complexes may constitute a major mechanism of tumor suppression.

Exome sequencing to identify de novo mutations in sporadic ALS trios.

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease whose causes are still poorly understood. To identify additional genetic risk factors, we assessed the role of de novo mutations in ALS by sequencing the exomes of 47 ALS patients and both of their unaffected parents (n = 141 exomes). We found that amino acid-altering de novo mutations were enriched in genes encoding chromatin regulators, including the neuronal chromatin remodeling complex (nBAF) component SS18L1 (also known as CREST). CREST mutations inhibited activity-dependent neurite outgrowth in primary neurons, and CREST associated with the ALS protein FUS. These findings expand our understanding of the ALS genetic landscape and provide a resource for future studies into the pathogenic mechanisms contributing to sporadic ALS.

Outbreak of carbapenem-resistant Providencia stuartii in an intensive care unit.

Outbreaks by carbapenem-resistant Providencia stuartii (CRPS) are rarely described. Clinical characteristics of patients with CRPS in an intensive care unit and resistance mechanisms were investigated. Carbapenemase production and/or outer membrane alterations were not detected; only CTX-M-2 and AmpC hyperproduction were noted. The outbreak was ultimately controlled in a 3-month period.

A time and a place for nkx2-1 in interneuron specification and migration.

The homeobox transcription factor, Nkx2-1, plays multiple roles during forebrain development. Using restricted genetic ablation of Nkx2-1, in this issue of Neuron, Butt et al. show that Nkx2-1 in telencephalic progenitors regulates interneuron subtype specification, while Nóbrega-Pereira et al. demonstrate that postmitotic Nkx2-1 regulates migration and sorting of interneurons to the striatum or cortex by controlling the expression of the guidance receptor, Neuropilin-2.

Organotypic slice culture of E18 rat brains.

Organotypic slice cultures from embryonic rodent brains are widely used to study brain development. While there are often advantages to an in-vivo system, organotypic slice cultures allow one to perform a number of manipulations that are not presently feasible in-vivo. To date, organtotypic embryonic brain slice cultures have been used to follow individual cells using time-lapse microscopy, manipulate the expression of genes in the ganglionic emanances (a region that is hard to target by in-utero electroporation), as well as for pharmacological studies. In this video protocol we demonstrate how to make organotypic slice cultures from rat embryonic day 18 embryos. The protocol involves dissecting the embryos, embedding them on ice in low melt agarose, slicing the embedded brains on the vibratome, and finally plating the slices onto filters in culture dishes. This protocol is also applicable in its present form to making organotypic slice cultures from different embryonic ages for both rats and mice.

In utero intraventricular injection and electroporation of E16 rat embryos.

In-utero in-vivo injection and electroporation of the embryonic rat neocortex provides a powerful tool for the manipulation of individual progenitors lining the walls of the lateral ventricle. This technique is now widely used to study the processes involved in corticogenesis by over-expressing or knocking down genes and observing the effects on cellular proliferation, migration, and differentiation. In comparison to traditional knockout strategies, in-utero electroporation provides a rapid means to manipulate a population of cells during a specific temporal window. In this video protocol we outline the experimental methodology for preparing rats for surgery, exposing the uterine horns through laporatomy, injecting DNA into the lateral ventricles of the developing embryo, electroporating DNA into the progenitors lining the lateral wall, and caring for animals post-surgery. Our laboratory uses this protocol for surgeries on E15-E21 rats, however it is most commonly performed at E16 as shown in this video.

In utero intraventricular injection and electroporation of E15 mouse embryos.

In-utero in-vivo injection and electroporation of the embryonic mouse neocortex provides a powerful tool for the manipulation of individual progenitors lining the walls of the lateral ventricle. This technique is now widely used to study the processes involved in corticogenesis by over-expressing or knocking down genes and observing the effects on cellular proliferation, migration, and differentiation. In comparison to traditional knockout strategies, in-utero electroporation provides a rapid means to manipulate a population of cells during a specific temporal window. In this video protocol we outline the experimental methodology for preparing mice for surgery, exposing the uterine horns through laporatomy, injecting DNA into the lateral ventricles of the developing embryo, electroporating DNA into the progenitors lining the lateral wall, and caring for animals post-surgery. Our laboratory uses this protocol for surgeries on E13-E16 mice, however it is most commonly performed at E15 as shown in this video.

Morbimortalidad por leucemias en Villa Clara, 1981-1995 / Morbidity-mortality due to leukemias in Villa Clara, 1981-1995

Se estudiaron 458 pacientes con leucemia diagnosticados y 351 fallecidos en un período de 15 años, comprendidos entre 1981 y 1995. Las leucemias agudas tuvieron una incidencia mayor (60,3 porciento) y predominó la leucemia aguda no linfoblástica. Las leucemias crónicas se comportaron de forma similar según las variedades mieloide y linfoide. En el sexo femenino predominaron las leucemias agudas, a razón de 2,3:1 y las leucemias crónicas en el sexo masculino con una proporción de 2:1. En la séptima y octava décadas de la vida se comunicó un mayor número de casos de leucemias: 173 pacientes (37,7 porciento) y en edades inferiores a 41 años predominaron las leucemias agudas (p < 0,05). El mayor número de fallecidos correspondió a las leucemias agudas con 208 casos. La causa más frecuente de muerte fueron las infecciones: 166 pacientes (47 porciento). La incidencia más alta de leucemia ocurrió en los años 1989 y 1993. La letalidad global por esta enfermedad fue del 76 porciento y constituyó el 2,2 porciento del total de enfermedades malignas en nuestra provincia

Valor del carbonato de litio en el tratamiento de la agranulocitosis / Value of lithium carbonate in agranulocytosis treatment

Se presenta un caso de agranulocitosis, en el cual se emplean las medidas del tratamiento convencional (aislamiento, antibiótico de amplio espectro, transfusiones de masa leucocitaria), sin obtenerse resultado favorable alguno, por lo que al décimo día de su ingreso se decide administrar carbonato de litio en dosis de 1 500 mg diarios, con lo que se obtuvo una evidente mejoría clínica y hematológica. El paciente es egresado posteriormente asintomático, con cifras de leucocitos, granulocitos y medulograma normales. Se hace una revisión bibliográfica del uso terapéutico del carbonato de litio