RESUMEN

Antibodies that block the interaction between PD-1 expressing T-cells and cancer cells expressing PD-L1 play a central role in contemporary immunotherapy regimes [1-3]. We previously reported the isolation of a single chain variable fragment (scFv) of the monoclonal anti-PD-1 antibody Nivolumab, that binds to purified PD-1 and blocked its interaction with PD-L1 [4]. This anti-PD-1 scFv did not, however, function in a cell-based assay designed to detect the disruption of the PD-1/PD-L1 interaction, a result likely due to its poor solubility in tissue culture media. Herein we report that following a series of structure-based rational design analyses, including Aggreescan3D, we have isolated a variant of the anti-PD-1 scFv having significantly improved solubility in tissue culture medium. Moreover, this soluble anti-PD-1 scFv variant disrupted the interaction between PD-1 expressed on Jurkat Cells and PD-L1 expressed on CHO cells. These findings are discussed in terms of the related observation that the residues mutated to form the anti-PD-1 variant are conserved in many other scFvs; thus, the properties of a range of scFvs will likely be enhanced by similar mutations of the conserved residues.

Asunto(s)

Antígeno B7-H1 , Anticuerpos de Cadena Única , Cricetinae , Animales , Humanos , Antígeno B7-H1/genética , Anticuerpos de Cadena Única/genética , Anticuerpos de Cadena Única/farmacología , Anticuerpos de Cadena Única/química , Nivolumab/farmacología , Células CHO , Cricetulus , Anticuerpos Monoclonales/genética

RESUMEN

OBJECTIVES: To determine whether oral cryotherapy (OC) mitigates oral mucositis (OM) resulting from busulfan chemotherapy. SAMPLE & SETTING: Electronic health records of patients undergoing busulfan conditioning for blood and marrow transplantation were reviewed for this descriptive study. The post-OC group received OC with busulfan, but the pre-OC group did not. METHODS & VARIABLES: Demographic and disease characteristics for both groups were summarized using descriptive statistics. Wilcoxon rank-sum test was performed for continuous and ordinal measures, and chi-square tests were performed for categorical outcomes between the two groups. RESULTS: This study found a decrease in the severity of OM as assessed by the World Health Organization OM scale. This study also found a reduction of total parenteral nutrition and opioid pain medication use, as well as a decrease in length of stay and airway protection-related intensive care unit transfers. An increase in day 11 methotrexate administration for graft-versus-host disease prophylaxis was observed in the post-OC group. IMPLICATIONS FOR NURSING: OC is a safe and easily implemented intervention that can decrease OM in patients receiving busulfan chemotherapy.

Asunto(s)

Trasplante de Células Madre Hematopoyéticas , Estomatitis , Humanos , Busulfano/efectos adversos , Crioterapia/métodos , Trasplante de Células Madre Hematopoyéticas/efectos adversos , Estudios Prospectivos , Estudios Retrospectivos , Estomatitis/inducido químicamente , Estomatitis/tratamiento farmacológico , Acondicionamiento Pretrasplante/efectos adversos

RESUMEN

Activated T-cells express Programmed cell Death protein 1 (PD-1), a key immune checkpoint receptor. PD-1 functions primarily in peripheral tissues, where T cells may encounter tumor-derived immunosuppressive ligands. Monoclonal antibodies that disrupt the interaction between T-cell derived PD-1 and immunosuppressive ligands, such as PD-L1, have revolutionized approaches to cancer therapy. For instance, Nivolumab is a monoclonal Ab that targets human PD-1 and has played an important role in immune checkpoint therapy. Herein we report the purification and initial characterization of a ~27 kDa single chain variable fragment (scFv) of Nivolumab that targets human PD-1 and blocks binding by PD-L1. The possibility that the anti-PD-1 scFv can serve as both an anti-tumor agent and as an anti-viral agent is discussed. IMPORTANCE: The clinical significance of anti-PD-1 antibodies for treatment of a range of solid tumors is well documented (reviewed in [1-4]). In this report, we describe the results of studies that establish that an anti-PD-1 scFv purified from E. coli binds tightly to human PD-1. Furthermore, we demonstrate that upon binding, the anti-PD-1 scFv disrupts the interaction between PD-1 and PD-L1. Thus, the properties of this scFv, including its small size, stability and affinity for human PD-1, suggest that it has the potential to be a useful reagent in subsequent immunotherapeutic, diagnostic and anti-viral applications.

Asunto(s)

Antígeno B7-H1/química , Nivolumab/química , Receptor de Muerte Celular Programada 1/química , Anticuerpos de Cadena Única/química , Secuencia de Aminoácidos , Antígeno B7-H1/genética , Antígeno B7-H1/inmunología , Sitios de Unión , Clonación Molecular , Escherichia coli/genética , Escherichia coli/metabolismo , Expresión Génica , Vectores Genéticos/química , Vectores Genéticos/metabolismo , Humanos , Modelos Moleculares , Nivolumab/genética , Nivolumab/inmunología , Receptor de Muerte Celular Programada 1/antagonistas & inhibidores , Receptor de Muerte Celular Programada 1/genética , Receptor de Muerte Celular Programada 1/inmunología , Unión Proteica , Dominios y Motivos de Interacción de Proteínas , Estructura Secundaria de Proteína , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/inmunología , Alineación de Secuencia , Homología de Secuencia de Aminoácido , Anticuerpos de Cadena Única/genética , Anticuerpos de Cadena Única/inmunología , Linfocitos T/química , Linfocitos T/inmunología

RESUMEN

When purified from persistent infections, the genomes of most human polyomaviruses contain single enhancers. However, when isolated from productively infected cells from immunocompromised individuals, the genomes of several polyomaviruses contain duplicated enhancers that promote a number of polyoma-based diseases. The mechanism(s) that gives rise to the duplicated enhancers in the polyomaviruses is, however, not known. Herein we propose a model for the duplication of the enhancers that is based on recent advances in our understanding of; 1) the initiation of polyomavirus DNA replication, 2) the formation of long flaps via displacement synthesis and 3) the subsequent generation of duplicated enhancers via double stranded break repair. Finally, we discuss the possibility that the polyomavirus based replication dependent enhancer duplication model may be relevant to the enhancer-associated rearrangements detected in human genomes that are associated with various diseases, including cancers.

Asunto(s)

Reparación del ADN/genética , ADN Viral/biosíntesis , Poliomavirus/genética , Replicación Viral/genética , Animales , ADN/genética , Roturas del ADN de Doble Cadena , Elementos Transponibles de ADN , Elementos de Facilitación Genéticos , Humanos , Modelos Genéticos , Infecciones por Polyomavirus/virología

RESUMEN

Neurosurgical shunts occasionally act as a conduit for seeding of central nervous system tumours to the abdomen. Retrograde spread of extra-neural tumours to the central nervous system is exceedingly rare. We report the first case of an abdominal primary tumour spreading to the spinal cord via a lumbo-peritoneal shunt. This is also the first case report of a struma ovarii tumour metastasis to the central nervous system via any route.

Asunto(s)

Neoplasias Ováricas , Estruma Ovárico , Femenino , Humanos , Neoplasias Ováricas/diagnóstico , Neoplasias Ováricas/cirugía , Estruma Ovárico/diagnóstico , Estruma Ovárico/cirugía

RESUMEN

BACKGROUND: Anxiety and depression often co-exist. These disorders are under-diagnosed and under-treated, specifically among older people, and lead to increased use of health and social care services and raised mortality. Older people report a reluctance to present to their GP with depression or anxiety symptoms due to perceived stigma about mental health problems, lack of acceptable treatments and the prioritising of physical health problems. Third sector organisations, who work closely with older people in the community, are well-placed to provide additional support. We developed a brief intervention based on principles of Behavioural Activation, with encouragement to participate in a group activity, for delivery by Support Workers from AgeUK. The aim of the study was to examine whether this brief intervention could be delivered to older people with anxiety and/or depression, with sufficient fidelity, and whether this approach was acceptable to patients, GPs and AgeUK Support Workers. METHODS: Semi-structured interviews with older people with self-reported anxiety and/or depression (who received the intervention), Support Workers and GPs to assess acceptability of the intervention and impact on routine care. A constant comparative approach was used to analyse the data. Intervention sessions between Support Workers and older people were digitally recorded and reviewed by the research team to assess fidelity. RESULTS: The Support Workers delivered the intervention with fidelity; access to the training maual and ongoing supervision were important. Older people found the intervention acceptable and valued the one-to-one support they received; group activities suggested by Support Workers were not valued by all. GPs recognised the need for additional support for vulnerable older people, but acknowledged they could not provide this support. Participation in the study did not impact on GP routine care, other than responding to the calls from the study team about risk of self-harm. CONCLUSIONS: Support Workers within AgeUK, can be recruited and trained to deliver an intervention, based on the principles of Behavioural Activation, to older people with anxiety and/or depression. The training and supervision model used in the study was acceptable to Support Workers, and the intervention was acceptable to older people and GPs. This model has the potential to contribute to improving the support and care of older people in primary care with anxiety and depression. Further testing is required in a full trial. TRIAL REGISTRATION: Trial registration number ISRCTN16318986 . Registered 10/11/2016.

Asunto(s)

Ansiedad/terapia , Actitud del Personal de Salud , Depresión/terapia , Médicos Generales , Auxiliares de Salud a Domicilio , Aceptación de la Atención de Salud , Anciano , Anciano de 80 o más Años , Terapia Cognitivo-Conductual , Estudios de Factibilidad , Femenino , Humanos , Masculino , Persona de Mediana Edad , Proyectos Piloto , Investigación Cualitativa , Ensayos Clínicos Controlados Aleatorios como Asunto , Reino Unido

RESUMEN

BACKGROUND: Anxiety and depression are common among older people, with up to 20% reporting such symptoms, and the prevalence increases with co-morbid chronic physical health problems. Access to treatment for anxiety and depression in this population is poor due to a combination of factors at the level of patient, practitioner and healthcare system. There is evidence to suggest that older people with anxiety and/or depression may benefit both from one-to-one interventions and group social or educational activities, which reduce loneliness, are participatory and offer some activity. Non-traditional providers (support workers) working within third-sector (voluntary) organisations are a valuable source of expertise within the community but are under-utilised by primary care practitioners. Such a resource could increase access to care, and be less stigmatising and more acceptable for older people. METHODS: The study is in three phases and this paper describes the protocol for phase III, which will evaluate the feasibility of recruiting general practices and patients into the study, and determine whether support workers can deliver the intervention to older people with sufficient fidelity and whether this approach is acceptable to patients, general practitioners and the third-sector providers. Phase III of the NOTEPAD study is a randomised controlled trial (RCT) that is individually randomised. It recruited participants from approximately six general practices in the UK. In total, 100 participants aged 65 years and over who score 10 or more on PHQ9 or GAD7 for anxiety or depression will be recruited and randomised to the intervention or usual general practice care. A mixed methods approach will be used and follow-up will be conducted 12 weeks post-randomisation. DISCUSSION: This study will inform the design and methods of a future full-scale RCT. TRIAL REGISTRATION: ISRCTN, ID: ISRCTN16318986 . Registered 10 November 2016. The ISRCTN registration is in line with the World Health Organization Trial Registration Data Set. The present paper represents the original version of the protocol. Any changes to the protocol will be communicated to ISRCTN.

Asunto(s)

Envejecimiento/psicología , Ansiedad/terapia , Terapia Cognitivo-Conductual/métodos , Servicios Comunitarios de Salud Mental , Depresión/terapia , Servicios de Salud para Ancianos , Sistemas de Apoyo Psicosocial , Trabajadores Sociales , Afecto , Factores de Edad , Anciano , Ansiedad/diagnóstico , Ansiedad/psicología , Depresión/diagnóstico , Depresión/fisiopatología , Estudios de Factibilidad , Femenino , Humanos , Soledad , Masculino , Salud Mental , Estudios Multicéntricos como Asunto , Atención Primaria de Salud , Calidad de Vida , Ensayos Clínicos Controlados Aleatorios como Asunto , Factores de Tiempo , Resultado del Tratamiento , Reino Unido

RESUMEN

Progressive multifocal leukoencephalopathy (PML) is an often-fatal demyelinating disease of the central nervous system. PML results when oligodendrocytes within immunocompromised individuals are infected with the human JC virus (JCV). We have identified an oligodendrocyte precursor cell line, termed G144, that supports robust levels of JCV DNA replication, a central part of the JCV life cycle. In addition, we have determined that JC virus readily infects G144 cells. Furthermore, we have determined that JCV DNA replication in G144 cells is stimulated by myristoylated (i.e., constitutively active) Akt and reduced by the Akt-specific inhibitor MK2206. Thus, this oligodendrocyte-based model system will be useful for a number of purposes, such as studies of JCV infection, establishing key pathways needed for the regulation of JCV DNA replication, and identifying inhibitors of this process.IMPORTANCE The disease progressive multifocal leukoencephalopathy (PML) is caused by the infection of particular brain cells, termed oligodendrocytes, by the JC virus. Studies of PML, however, have been hampered by the lack of an immortalized human cell line derived from oligodendrocytes. Here, we report that the G144 oligodendrocyte cell line supports both infection by JC virus and robust levels of JCV DNA replication. Moreover, we have established that the Akt pathway regulates JCV DNA replication and that JCV DNA replication can be inhibited by MK2206, a compound that is specific for Akt. These and related findings suggest that we have established a powerful oligodendrocyte-based model system for studies of JCV-dependent PML.

Asunto(s)

Virus JC/fisiología , Oligodendroglía/virología , Proteína Oncogénica v-akt/metabolismo , Replicación Viral , Línea Celular , Replicación del ADN , ADN Viral , Compuestos Heterocíclicos con 3 Anillos/farmacología , Humanos , Virus JC/genética , Leucoencefalopatía Multifocal Progresiva/virología , Oligodendroglía/efectos de los fármacos , Proteína Oncogénica v-akt/antagonistas & inhibidores , Proteína Oncogénica v-akt/química

RESUMEN

BACKGROUND: One-in-five people in the UK experience anxiety and/or depression in later life. However, anxiety and depression remain poorly detected in older people, particularly in those with chronic physical ill health. In the UK, a stepped care approach, to manage common mental health problems, is advocated which includes service provision from non-statutory organisations (including third/voluntary sector). However, evidence to support such provision, including the most effective interventions, is limited. The qualitative study reported here constitutes the first phase of a feasibility study which aims to assess whether third sector workers can deliver a psychosocial intervention to older people with anxiety and/or depression. The aim of this qualitative study is to explore the views of older people and third sector workers about anxiety and depression among older people in order to refine an intervention to be delivered by third sector workers. METHODS: Semi-structured interviews with participants recruited through purposive sampling from third sector groups in North Staffordshire. Interviews were digitally recorded with consent, transcribed and analysed using principles of constant comparison. RESULTS: Nineteen older people and 9 third sector workers were interviewed. Key themes included: multiple forms of loss, mental health as a personal burden to bear, having courage and providing/receiving encouragement, self-worth and the value of group activities, and tensions in existing service provision, including barriers and gaps. CONCLUSIONS: The experience of loss was seen as central to feelings of anxiety and depression among community-dwelling older people. This study contributes to the evidence pointing to the scale and severity of mental health needs for some older people which can arise from multiple forms of loss, and which present a significant challenge to health, social care and third sector services. The findings informed development of a psychosocial intervention and training for third sector workers to deliver the intervention.

Asunto(s)

Ansiedad/terapia , Servicios Comunitarios de Salud Mental/organización & administración , Depresión/terapia , Anciano , Femenino , Humanos , Masculino , Investigación Cualitativa , Reino Unido

RESUMEN

Within immunocompromised populations, the JC polyomavirus is the cause of the often-fatal disease Progressive Multifocal Leukoencephalopathy (PML). JC virus encodes a protein, termed T-antigen (T-ag), which is essential for its replication and pathogenicity. Previous studies of JCV T-ag have, in general, used antibodies raised against SV40 T-ag. Unfortunately, SV40 T-ag is also detected in humans and therefore there have been concerns about cross-reactivity. To address this issue, we have isolated a monoclonal antibody that binds to the JCV, but not the SV40, T-ag origin-binding domain (OBD). Furthermore, the region on the surface of the JCV T-ag OBD that is recognized by the "anti-JCV OBD mAb" has been mapped. We also demonstrate that the "anti-JCV OBD mAb" will be a useful reagent for standard techniques (e.g., Westerns blots and ELISAs). Finally, we note that additional monoclonal Abs that are specific for the T-ags encoded by the other human polyomaviruses could be generated by adopting the approach described herein.

Asunto(s)

Anticuerpos Monoclonales/química , Anticuerpos Monoclonales/inmunología , Antígenos Virales de Tumores/química , Antígenos Virales de Tumores/inmunología , Virus JC/inmunología , Dominios y Motivos de Interacción de Proteínas , Secuencias de Aminoácidos , Secuencia de Aminoácidos , Animales , Anticuerpos Monoclonales/aislamiento & purificación , Especificidad de Anticuerpos/inmunología , Antígenos Virales de Tumores/metabolismo , Sitios de Unión , Reacciones Cruzadas/inmunología , Mapeo Epitopo , Ratones , Modelos Moleculares , Unión Proteica , Conformación Proteica

RESUMEN

The replication of human polyomavirus JCV, which causes Progressive Multifocal Leukoencephalopathy, is initiated by the virally encoded T-antigen (T-ag). The structure of the JC virus T-ag origin-binding domain (OBD) was recently solved by X-ray crystallography. This structure revealed that the OBD contains a C-terminal pocket, and that residues from the multifunctional A1 and B2 motifs situated on a neighboring OBD molecule dock into the pocket. Related studies established that a mutation in a pocket residue (F258L) rendered JCV T-ag unable to support JCV DNA replication. To establish why this mutation inactivated JCV T-ag, we have solved the structure of the F258L JCV T-ag OBD mutant. Based on this structure, it is concluded that the structural consequences of the F258L mutation are limited to the pocket region. Further analyses, utilizing the available polyomavirus OBD structures, indicate that the F258 region is highly dynamic and that the relative positions of F258 are governed by DNA binding. The possible functional consequences of the DNA dependent rearrangements, including promotion of OBD cycling at the replication fork, are discussed.

Asunto(s)

Antígenos Virales de Tumores/metabolismo , Replicación del ADN/fisiología , ADN Viral/metabolismo , Virus JC/fisiología , Replicación Viral/fisiología , Secuencia de Aminoácidos , Antígenos Virales de Tumores/química , Sitios de Unión , Rastreo Diferencial de Calorimetría , Cristalografía por Rayos X , ADN Viral/química , Técnica del Anticuerpo Fluorescente , Humanos , Datos de Secuencia Molecular , Conformación Proteica

RESUMEN

Progressive Multifocal Leukoencephalopathy (PML) is caused by lytic replication of JC virus (JCV) in specific cells of the central nervous system. Like other polyomaviruses, JCV encodes a large T-antigen helicase needed for replication of the viral DNA. Here, we report the development of a luciferase-based, quantitative and high-throughput assay of JCV DNA replication in C33A cells, which, unlike the glial cell lines Hs 683 and U87, accumulate high levels of nuclear T-ag needed for robust replication. Using this assay, we investigated the requirement for different domains of T-ag, and for specific sequences within and flanking the viral origin, in JCV DNA replication. Beyond providing validation of the assay, these studies revealed an important stimulatory role of the transcription factor NF1 in JCV DNA replication. Finally, we show that the assay can be used for inhibitor testing, highlighting its value for the identification of antiviral drugs targeting JCV DNA replication.

Asunto(s)

Replicación del ADN/fisiología , ADN Viral/fisiología , Virus JC/fisiología , Línea Celular Tumoral , Elementos de Facilitación Genéticos , Regulación Viral de la Expresión Génica/fisiología , Humanos , Virus JC/genética , Modelos Moleculares , Regiones Promotoras Genéticas , Conformación Proteica , Proteínas Virales/genética , Proteínas Virales/metabolismo , Replicación Viral

RESUMEN

JC virus is a member of the Polyomavirus family of DNA tumor viruses and the causative agent of progressive multifocal leukoencephalopathy (PML). PML is a disease that occurs primarily in people who are immunocompromised and is usually fatal. As with other Polyomavirus family members, the replication of JC virus (JCV) DNA is dependent upon the virally encoded protein T-antigen. To further our understanding of JCV replication, we have determined the crystal structure of the origin-binding domain (OBD) of JCV T-antigen. This structure provides the first molecular understanding of JCV T-ag replication functions; for example, it suggests how the JCV T-ag OBD site-specifically binds to the major groove of GAGGC sequences in the origin. Furthermore, these studies suggest how the JCV OBDs interact during subsequent oligomerization events. We also report that the OBD contains a novel "pocket"; which sequesters the A1 & B2 loops of neighboring molecules. Mutagenesis of a residue in the pocket associated with the JCV T-ag OBD interfered with viral replication. Finally, we report that relative to the SV40 OBD, the surface of the JCV OBD contains one hemisphere that is highly conserved and one that is highly variable.

Asunto(s)

Antígenos Virales de Tumores/química , Replicación del ADN/genética , Virus JC/química , Virus JC/genética , Replicación Viral/genética , Secuencia de Aminoácidos , Sitios de Unión/fisiología , Cristalización , Cristalografía por Rayos X , Virus JC/fisiología , Datos de Secuencia Molecular , Estructura Cuaternaria de Proteína

RESUMEN

NMR is ideal for characterizing non-enzymatic protein glycation, including AGEs (advanced glycation endproducts) underlying tissue pathologies in diabetes and ageing. Ribose, R5P (ribose-5-phosphate) and ADPR (ADP-ribose), could be significant and underinvestigated biological glycating agents especially in chronic inflammation. Using [U-13C]ribose we have identified a novel glycoxidation adduct, 5-deoxy-5-desmethylpronyl-lysine, 'norpronyl-lysine', as well as numerous free ketones, acids and amino group reaction products. Glycation by R5P and ADPR proceeds rapidly with R5P generating a brown precipitate with PLL (poly-L-lysine) within hours. ssNMR (solid-state NMR) 13C-13C COSY identifies several crosslinking adducts such as the newly identified norpronyl-lysine, in situ, from the glycating reaction of 13C5-ribose with collagen. The same adducts are also identifiable after reaction of collagen with R5P. We also demonstrate for the first time bio-amine (spermidine, N-acetyl lysine, PLL) catalysed ribose 2-epimerization to arabinose at physiological pH. This work raises the prospect of advancing understanding of the mechanisms and consequences of glycation in actual tissues, in vitro or even ex vivo, using NMR isotope-labelled glycating agents, without analyses requiring chemical or enzymatic degradations, or prior assumptions about glycation products.

Asunto(s)

Adenosina Difosfato Ribosa/química , Colágeno/química , Modelos Químicos , Resonancia Magnética Nuclear Biomolecular , Ribosamonofosfatos/química , Animales , Glicosilación

RESUMEN

Polyomavirus origins of replication contain multiple occurrences of G(A/G)GGC, the high-affinity binding element for the viral initiator T-antigen (T-ag). The site I regulatory region of simian virus 40, involved in the repression of transcription and the enhancement of DNA replication initiation, contains two GAGGC sequences arranged head to tail and separated by a 7-bp AT-rich sequence. We have solved a 3.2-Å costructure of the SV40 origin-binding domain (OBD) bound to site I. We have also established that T-ag assembly on site I is limited to the formation of a single hexamer. These observations have enabled an analysis of the role(s) of the OBDs bound to the site I pentanucleotides in hexamer formation. Of interest, they reveal a correlation between the OBDs bound to site I and a pair of OBD subunits in the previously described hexameric spiral structure. Based on these findings, we propose that spiral assembly is promoted by pentanucleotide pairs arranged in a head-to-tail manner. Finally, the possibility that spiral assembly by OBD subunits accounts for the heterogeneous distribution of pentanucleotides found in the origins of replication of polyomaviruses is discussed.

Asunto(s)

Antígenos Transformadores de Poliomavirus/química , ADN Viral/metabolismo , Virus 40 de los Simios/genética , Antígenos Transformadores de Poliomavirus/genética , Antígenos Transformadores de Poliomavirus/metabolismo , Secuencia de Bases , Sitios de Unión , Cristalografía por Rayos X , Replicación del ADN , ADN Viral/química , Proteínas de Unión al ADN/química , Proteínas de Unión al ADN/genética , Modelos Moleculares , Unión Proteica , Multimerización de Proteína , Origen de Réplica/genética , Transcripción Genética

RESUMEN

The morphological study of extinct taxa allows for analysis of a diverse set of macroevolutionary hypotheses, including testing for change in the magnitude of morphological divergence, extinction selectivity on form, and the ecological context of radiations. Late Ordovician graptoloids experienced a phylogenetic bottleneck at the Hirnantian mass extinction (∼445 Ma), when a major clade of graptoloids was driven to extinction while another clade simultaneously radiated. In this study, we developed a dataset of 49 ecologically relevant characters for 183 species with which we tested two main hypotheses: (i) could the biased survival of one graptoloid clade over another have resulted from morphological selectivity alone and (ii) are the temporal patterns of morphological disparity and innovation during the recovery consistent with an interpretation as an adaptive radiation resulting from ecological release? We find that a general model of morphological selectivity has a low probability of producing the observed pattern of taxonomic selectivity. Contrary to predictions from theory on adaptive radiations and ecological speciation, changes in disparity and species richness are uncoupled. We also find that the early recovery is unexpectedly characterized by relatively low morphological disparity and innovation, despite also being an interval of elevated speciation. Because it is necessary to invoke factors other than ecology to explain the graptoloid recovery, more complex models may be needed to explain recovery dynamics after mass extinctions.

Asunto(s)

Biodiversidad , Cordados no Vertebrados/fisiología , Extinción Biológica , Fósiles , Zooplancton/fisiología , Animales , Cordados no Vertebrados/anatomía & histología , Cordados no Vertebrados/clasificación , Ecosistema , Especiación Genética , Sedimentos Geológicos , Modelos Biológicos , Filogenia , Especificidad de la Especie , Zooplancton/clasificación

RESUMEN

The 'beads task' is used to measure the cognitive basis of delusions, namely the 'Jumping to Conclusions' (JTC) reasoning bias. However, it is not clear whether the task merely taps executive dysfunction - known to be impaired in patients with schizophrenia - such as planning and resistance to impulse. To study this, 19 individuals with neurosurgical excisions to the prefrontal cortex, 21 unmedicated adults with Attention Deficit Hyperactivity Disorder (ADHD), and 25 healthy controls completed two conditions of the beads task, in addition to tests of memory and executive function as well as control tests of probabilistic reasoning ability. The results indicated that the prefrontal lobe group (in particular, those with left-sided lesions) demonstrated a JTC bias relative to the ADHD and control groups. Further exploratory analyses indicated that JTC on the beads task was associated with poorer performance in certain executive domains. The results are discussed in terms of the executive demands of the beads task and possible implications for the model of psychotic delusions based on the JTC bias.

Asunto(s)

Trastorno por Déficit de Atención con Hiperactividad/psicología , Deluciones/fisiopatología , Deluciones/psicología , Corteza Prefrontal/fisiología , Desempeño Psicomotor/fisiología , Adolescente , Adulto , Anciano , Trastorno por Déficit de Atención con Hiperactividad/fisiopatología , Toma de Decisiones/fisiología , Función Ejecutiva/fisiología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Pruebas Neuropsicológicas/estadística & datos numéricos , Corteza Prefrontal/cirugía

RESUMEN

The modular multifunctional protein large T antigen (T-ag) from simian virus 40 orchestrates many of the events needed for replication of the viral double-stranded DNA genome. This protein assembles into single and double hexamers on specific DNA sequences located at the origin of replication. This complicated process begins when the origin-binding domain of large T antigen (T-ag ODB) binds the GAGGC sequences in the central region (site II) of the viral origin of replication. While many of the functions of purified T-ag OBD can be studied in isolation, it is primarily monomeric in solution and cannot assemble into hexamers. To overcome this limitation, the possibility of engineering intermolecular disulfide bonds in the origin-binding domain which could oligomerize in solution was investigated. A recent crystal structure of the wild-type T-ag OBD showed that this domain forms a left-handed spiral in the crystal with six subunits per turn. Therefore, we analyzed the protein interface of this structure and identified two residues that could potentially support an intermolecular disulfide bond if changed to cysteines. SDS-PAGE analysis established that the mutant T-ag OBD formed higher oligomeric products in a redox-dependent manner. In addition, the 1.7 Å resolution crystal structure of the engineered disulfide-linked T-ag OBD is reported, which establishes that oligomerization took place in the expected manner.

Asunto(s)

Antígenos Virales de Tumores/química , ADN/química , Disulfuros/química , Virus 40 de los Simios/química , Antígenos Virales de Tumores/genética , Antígenos Virales de Tumores/metabolismo , Biocatálisis , ADN/metabolismo , Replicación del ADN , Modelos Moleculares , Mutación , Estructura Cuaternaria de Proteína , Virus 40 de los Simios/genética , Virus 40 de los Simios/metabolismo