The effects of typical ageing on cognitive control: recent advances and future directions

Cognitive control is one of the most fundamental aspects of human life. Its ageing is an important contemporary research area due to the needs of the growing ageing population, such as prolonged independence and quality of life. Traditional ageing research argued for a global decline in cognitive control with age, typically characterised by slowing processing speed and driven by changes in the frontal cortex. However, recent advances questioned this perspective by demonstrating high heterogeneity in the ageing data, domain-specific declines, activity changes in resting state networks, and increased functional connectivity. Moreover, improvements in neuroimaging techniques have enabled researchers to develop compensatory models of neural reorganisation that helps negate the effects of neural losses and promote cognitive control. In this article on typical ageing, we review recent behavioural and neural findings related to the decline in cognitive control among older adults. We begin by reviewing traditional perspectives and continue with how recent work challenged those perspectives. In the discussion section, we propose key areas of focus for future research in the field.

Monitoring of optic nerve function in Neurofibromatosis 2 children with optic nerve sheath meningiomas using multifocal visual evoked potentials

Monitoring optic nerve sheath meningiomas (ONSM) in Neurofibromatosis type 2 (NF2) patients remains difficult. Other ocular manifestations of NF2 may obscure ophthalmic assessment of optic nerve function in these patients. Serial magnetic resonance imaging (MRI) used to assess the optic nerve is not without limitations, being expensive and often requiring general anaesthetic in children, with associated risks. This study was undertaken to describe the use of multifocal visual evoked potentials (multifocal VEP, mfVEP) in the regular monitoring of NF2 patients with ONSM. This study involved three NF2 patients with ONSM who undertook mfVEP testing at an academic ophthalmic centre. Same day mfVEP and routine ophthalmic testing were undertaken. Topographical function of the optic nerve was assessed, utilising tools such as asymmetry deviation and accumap severity index. Results were assessed alongside MRI and visual acuity (VA). From the three patients, five eyes had ONSMs, of which two caused unilateral blindness. The remaining three affected eyes had initial VAs 6/6, 6/24, and 6/18. Over follow up, ranging from 5 to 12 years, all tumours progressed, and VA declined for all patients. Multifocal VEP detected optic nerve functional loss corresponding with visual decline. This case series suggests mfVEP is effective in the objective topographic monitoring of optic nerve function in NF2 patients with ONSM. Due also to its safety in a paediatric population, the test may be considered in the routine monitoring of these patients, to be used to assist regular ophthalmic review and MRI scans.

Controlling processing temperatures and self-limiting behaviour in intense pulsed sintering by tailoring nanomaterial shape distribution

Intense pulsed light sintering of Ag nanoparticle–nanowire films shows reduced peak temperatures and a self-limiting behavior controlled by NW content.

Epilepsy in patients with primary brain tumors: The impact on mood, cognition, and HRQOL

BACKGROUND

A primary brain tumor (PBT) is often a fatal disease of the nervous system and has a serious impact on health-related quality of life (HRQOL). Presence of epilepsy and adverse reactions from tumor and epilepsy treatments may cause additional decline in HRQOL.

OBJECTIVES

We aimed to study the impact of epileptic seizures on cognition, mood, and HRQOL in patients with brain tumor-related epilepsy.

MATERIALS AND METHOD

Patients were grouped on an ordinal scale according to epilepsy burden from none to severe based on the presence of epileptic seizures and seizure frequency: L1, no epilepsy; L2, with epilepsy, seizure-free in the last 6 months with antiepileptic drugs; and L3, with epilepsy, at least one seizure in the last 6 months with AEDs. Health-related quality of life was measured by Functional Assessment of Cancer Therapy-Brain (FACT-Br) and Quality of Life in Epilepsy-31 (QOLIE-31) tools, cognition by the Montreal Cognitive Assessment (MoCA) tool and Frontal Assessment Battery (FAB), mood by the Hospital Anxiety and Depression Scale (HADS), activities of daily living (ADLs) by the Barthel Index (BI), and performance status by the Karnofsky Performance Status (KPS) scale in patients with primary brain tumors at least one month following neurosurgery with or without radiotherapy and chemotherapy.

RESULTS

Eighty-one patients with a diagnosis of primary brain tumors were recruited. Sixty-eight percent of patients were diagnosed with primary brain tumor-related epilepsy, 50.61% patients had cognitive impairment, 33% had abnormal scores in the anxiety scale, and 34% had abnormal scores in the depression scale. There were no statistically significant differences in these scores among L1, L2, and L3 groups. There were statistically significant differences in duration of disease and KPS and BI scores between L1 and L3 groups. The L3 group has significantly longer duration of disease and scored low in both the BI and KPS scale when compared to the L1 group. All patients with primary brain tumors scored significantly low in FACT-Br 'physical well-being' (PWB) and 'emotional well-being' (EWB) and high in 'social well-being' (SWB) when compared to healthy controls. When scores of each group were individually compared to healthy controls, the L3 group showed the lowest scores in PWB, EWB, and 'functional well-being'. In SWB, L1 and L2 groups showed statistically significantly high scores when compared to normative data. The QOLIE-31 applied to groups with epilepsy showed statistically significantly lower scores in the L3 group when compared to the L2 group in 'cognitive' and 'social functioning' domains. On multivariate analysis, both poor performance status and frequency of seizures were found to be independent risk factors for poor HRQOL when FACT-Br mean scores were compared. Level of seizures was found to be an independent risk factor for poor HRQOL when QOLIE-31 scores were compared between L2 and L3 groups.

DISCUSSION

Presence of brain tumors could be attributed to cognitive impairment irrespective of the presence of epilepsy in our cohort. High seizure burden is an independent risk factor for poor HRQOL in patients with primary brain tumors. The QOLIE-31 is a more sensitive tool than the FACT-Br because of the presence of a seizure-related questionnaire.

Systemic lupus erythematosus due to C1q deficiency with progressive encephalopathy, intracranial calcification and acquired moyamoya cerebral vasculopathy

We report a female with infantile onset of systemic lupus erythematosus secondary to C1q deficiency, in whom we identified a novel homozygous mutation in C1qB. The patient developed a progressive encephalopathy associated with spasticity, and suffered several arterial ischaemic strokes. Cerebral imaging demonstrated acquired intracranial calcification and a cerebral vasculopathy reminiscent of moyamoya. This case demonstrates overlap with some features of Aicardi-Goutières syndrome which, like C1q deficiency, is a monogenic cause of inflammation involving dysregulation of the innate immune system and stimulation of a type I interferon response.

Acute Subdural Haematoma in the Presence of an Intrathecal Catheter Placed for the Prevention of Post-Dural Puncture Headache

A 31-year-old term primigravid woman had an intrathecal catheter placed following a dural puncture during attempted epidural analgesia during labour. After 23 hours she developed sudden loss of consciousness and an urgent brain computed tomography scan demonstrated a large left hyper-acute subdural haematoma. Craniotomy revealed active bleeding from a ruptured left temporal bridging vein. She was extubated 12 hours after surgery and was discharged home 11 days later without neurological deficit. Although subdural haematoma is a recognised complication of dural puncture, it has not been reported in the presence of an intrathecal catheter. An intrathecal catheter may not always prevent cerebrospinal fluid efflux, so subdural haematoma remains a potential complication of inadvertent dural puncture.

Growth factor-assisted chemotherapy--the Manchester experience

Stimulation of red cell production by erythropoietin and of granulocyte production by granulocyte colony-stimulating factor (G-CSF) and granulocyte macrophage-CSF (GM-CSF) has been demonstrated in several clinical studies. The first study to show that a human CSF could be used to shorten the period of neutropenia and reduce the risk of serious infection following intensive combination chemotherapy was carried out in Manchester using G-CSF. The period of neutropenia was significantly shortenened (by a median of 80%) and the neutrophil count levels were restored and above normal by 14 days after chemotherapy. In view of these results a further study was undertaken to examine the possibility of using intensive two weekly chemotherapy under cover of G-CSF. Treatment with Doxorubicin at doses of 75, 100, 125 and 150 mg/m2 was followed by infusion of G-CSF for 11 days. The neutrophil counts returned to normal within 12-14 days, allowing the delivery of up to three cycles of high dose chemotherapy at 14 day intervals. These studies demonstrated that intensive chemotherapy with dose-limiting myelodepression can be given with increased frequency under cover of G-CSF. Our studies using GM-CSF have also shown that administration by continuous i.v. infusion can reduce the period of life-threatening neutropenia following high dose Melphalan (120 mg/m2) without resort to autologous bone marrow transplantation (ABMT). In this study the period of granulocytopenia following Melphalan (less than 500 g x 10(9)/m2) was less than 15 days. This compares favourably with other series using high dose Melphalan followed by ABMT without CSF, where the duration of severe neutropenia was prolonged beyond three weeks. Although it appears that G-CSF and GM-CSF should be given either by continuous i.v. infusion or s.c. injection at doses between 3-10 micrograms/kg/day to obtain maximum biological effect, a great deal more work is required to determine optimum schedules and investigate the possibility of using more than one bioregulator.

Continuous intrathecal baclofen infusion for children with cerebral palsy: a pilot study

OBJECTIVES

To determine whether continuous intrathecal baclofen infusion (CIBI) would decrease spasticity and improve function in children with spastic cerebral palsy.

DESIGN

Prospective study with measurement of changes from baseline assessed at regular intervals for 6 months following the intervention.

PATIENTS

Two subjects aged 8 and 9 years with cerebral palsy. Inclusion criteria included severe spasticity and age greater than 4 years. STUDY CENTRE: Department of Rehabilitation, The Children's Hospital at Westmead, Westmead, New South Wales, Australia.

RESULTS

Both subjects had clinically significant reductions in lower limb spasticity from a single intrathecal dose of baclofen (screening procedure), and had intrathecal pumps implanted. An intensive physical therapy programme was provided for both subjects in the 1-3-month period after commencing CIBI, in order to maximize functional gains. Modified Ashworth Scale scores remained reduced during the 6-month study period. There was a clinically significant increase in upper limb function for Subject 1. Gross Motor Function Measure scores decreased from 22% to 19% for Subject 1, and increased from 6% to 10% for Subject 2 over the study period. Paediatric Evaluation of Disability Inventory scores for Subject 1 showed a reduction in the level of caregiver assistance required, while Subject 2 showed significant improvement in the functional mobility domain. The major changes noted in the parent questionnaires were reduction in tone, increased range of motion and reduced time taken helping with activities of daily living such as toilet and dressing. No significant side-effect was seen after the screening procedure or after continuous intrathecal infusion. Both subjects' parents felt their child was improved following the intervention.

CONCLUSIONS

Children with spastic cerebral palsy can have their spasticity effectively reduced with CIBI. In this study of two children, the clinical improvements were encouraging, and it is proposed that CIBI may be of benefit to those patients whose level of spasticity severely interferes with function. Further studies using multidimensional assessment approaches, with larger numbers of children, are warranted.

A GATA-2/estrogen receptor chimera functions as a ligand-dependent negative regulator of self-renewal

The transcription factor GATA-2 is expressed in hematopoietic stem and progenitor cells and is functionally implicated in their survival and proliferation. We have used estrogen and tamoxifen-inducible forms of GATA-2 to modulate the levels of GATA-2 in the IL-3-dependent multipotential hematopoietic progenitor cell model FDCP mix. Ligand-dependent induction of exogenous GATA-2 activity did not rescue cells deprived of IL-3 from apoptosis. However, induction of GATA-2 activity in cells cultured in IL-3 blocked factor-dependent self-renewal but not factor-dependent survival: Cells undergo cell cycle arrest and cease proliferating but do not apoptose. This was accompanied by differentiation down the monocytic and granulocytic pathways. Differentiation occurred in the presence of IL-3 and did not require addition of exogenous differentiation growth factors such as G-CSF or GM-CSF normally required to induce granulomonocytic differentiation of FDCP-mix cells. Conversely, EPO-dependent erythroid differentiation was inhibited by GATA-2 activation. These biological effects were obtained with levels of exogenous GATA-2 representing less than twofold increases over endogenous GATA-2 levels and were not observed in cells overexpressing GATA-1/ER. Similar effects on proliferation and differentiation were also observed in primary progenitor cells, freshly isolated from murine bone marrow and transduced with a GATA-2/ER-containing retrovirus. Taken together, these data suggest that threshold activities of GATA-2 in hematopoietic progenitor cells are a critical determinant in influencing self-renewal versus differentiation outcomes.

Multilineage gene expression precedes commitment in the hemopoietic system

We have tested the hypothesis that multipotential hemopoietic stem and progenitor cells prime several different lineage-affiliated programs of gene activity prior to unilineage commitment and differentiation. Using single cell RT-PCR we show that erythroid (beta-globin) and myeloid (myeloperoxidase) gene expression programs can be initiated by the same cell prior to exclusive commitment to the erythroid or granulocytic lineages. Furthermore, the multipotential state is characterized by the coexpression of several lineage-affiliated cytokine receptors. These data support a model of hemopoietic lineage specification in which unilineage commitment is prefaced by a "promiscuous" phase of multilineage locus activation.

Cloning of the murine homolog of the leukemia-associated PML gene

PML, a Ring-finger protein, participates in the disruption of normal myeloid differentiation when fused to the retinoic acid receptor alpha (RAR alpha) by the translocation between chromosomes (Chrs) 15 and 17 in acute promyelocytic leukemia (APL). As an initial step in the characterization of PML in species other than human, a murine cDNA clone of the PML gene was isolated and sequenced, and the intron/exon organization of the murine locus determined. The predicted amino acid sequence of the mouse PML protein shows 80% similarity to that of its human homolog. However, the mouse and human proteins show greater than 90% similarity in the proposed functional domains of the proteins. Despite its role in the etiology of APL, PML expression is not detectably altered during granulocytic differentiation in a murine in vitro system. Chromosomal localization of the Pml locus by somatic cell hybrids and by linkage analysis indicates that the gene maps to a region of mouse Chr 9 with known linkage homology to the region on human Chr 15q to which PML has been localized.

Targeted in vivo infection with a retroviral vector carrying the interleukin-3 (multi-CSF) gene leads to immortalization and leukemic transformation of primitive hematopoietic progenitor cells

To measure the effect of endogenous IL-3 (Multi-CSF) expression on hematopoietic cells in vivo, we have infected several kinds of hematopoietic cell populations with retroviral vectors carrying the IL-3 gene (M3MuV) in vitro and injected the virus-producing cells into mice to "target" the virus to sites of hematopoiesis. Mast cell lines (Elut cells) or multipotent cell lines (FDC-Pmix) were infected with MPSV-based replication defective retroviral vectors carrying either the neomycin resistance gene alone (M3neoV) or the neomycin gene plus the IL-3 gene (M3MuV). These cell lines produced infective retroviral particles consisting of the replication defective vectors and helper virus constitutively produced by the target cell populations. Irradiated and non-irradiated virus-producing Elut cells and the virus-producing FDC-Pmix cells were transplanted into syngeneic mice to "target" virus infection to the sites of hemopoiesis. Control mice injected with M3neoV-producing cells did not develop a disease up to 6 months following transplantation, whereas mice injected with M3MuV-producing cells developed a myeloproliferative disease within 3 months. Hematopoietic cell lines were rescued from diseased and control mice. In all cases these cell lines were of host origin. Cell lines derived from control mice were of basophil/mast cell morphology only, and required IL-3 for their continued proliferation (similar to cell lines derived from uninfected animals), whereas the cell lines generated from spleen and bone marrow cells of host mice with myeloproliferative disease carried the M3MuV vector, were G418 resistant and IL-3 independent. The biologic properties of M3MuV infected host derived cell lines varied considerably. Some were multipotential and could be induced to differentiate in response to stromal cells and serum factors, others were more restricted to the granulocyte/macrophage lineage but were also differentiation inducible, and some were blocked in differentiation at the myeloblast/promyelocyte stage. We conclude that the injected donor cells acted as "infectious centers" to facilitate the infection of host hematopoietic cells with the M3MuV vector. Our results indicate that the "targeted" in vivo infection of primitive hematopoietic cells with M3MuV can initiate the immortalization and leukaemogenesis of multipotential and lineage restricted progenitor cells.

Effects of the steel gene product on mouse primordial germ cells in culture

Mutations at the steel (sl) and dominant white spotting (W) loci in the mouse affect primordial germ cells (PGC), melanoblasts and haemopoietic stem cells. The W gene encodes a cell-surface receptor of the tyrosine kinase family, the proto-oncogene c-kit. In situ analysis has shown c-kit messenger RNA expression in PGC in the early genital ridges. The Sl gene encodes the ligand for this receptor, a peptide growth factor, called here stem cell factor (SCF). SCF mRNA is expressed in many regions of the early mouse embryo, including the areas of migration of these cell types. It is important now to identify the role of the Sl-W interaction in the development of these migratory embryonic stem cell populations. Using an in vitro assay system, we show that SCF increases both the overall numbers and colony sizes of migratory PGC isolated from wild-type mouse embryos, and cultured on irradiated feeder layers of STO cells (a mouse embryonic fibroblast line). In the absence of feeder cells, SCF causes a large increase in the initial survival and apparent motility of PGC in culture. But labelling with bromodeoxyuridine shows that SCF is not, by itself, a mitogen for PGC. SCF does not exert a chemotropic effect on PGC in in vitro assays. These results suggest that SCF in vivo is an essential requirement for PGC survival. This demonstrates the control of the early germ-line population by a specific trophic factor.

Retroviral vectors related to the myeloproliferative sarcoma virus allow efficient expression in hematopoietic stem and precursor cell lines, but retroviral infection is reduced in more primitive cells

Retroviral vectors are considered to be the most suited vehicles for somatic gene therapy with hematopoietic stem cells as targets. Retrovirus-mediated gene transfer into differentiation-restricted hematopoietic precursor (FDC-P1, FDC-P2) and multipotent progenitor (stem) cell lines (FDC-Pmix) is inefficient. Two cellular restrictions are involved. One is specific for stem but not precursor cells and is at the level of transcription. Due to a unique property of the transcriptional control region of the myeloproliferative sarcoma virus (MPSV), vectors derived from MPSV are not affected by this block. The second restriction occurs before proviral DNA synthesis and integration. This inhibition of effective viral infection depends on the state of differentiation, being more pronounced in multipotent clonogenic blast cells. This block to retroviral infection affects all retroviral vectors tested.

Lack of response of bone marrow, in vitro, to growth factors in congenital neutropenia

Severe congenital neutropenia has a poor outlook. In vitro clonogenic assays using recombinant growth factors may improve understanding of the underlying pathogenetic mechanisms and identify those in whom growth factors might be clinically useful. Marrow from a boy with congenital neutropenia was cultured with a variety of recombinant growth factors. The results show that the neutropenia did not result from a lack of myeloid progenitors but that these progenitors could not produce mature neutrophils. Bone marrow transplantation is being considered as the most likely approach to correct neutropenia.

Rates of mutation to growth factor autonomy and tumorigenicity differ in hematopoietic stem and precursor cells expressing the multilineage colony-stimulating factor gene

At least two separate but interdependent events are required to attain autonomous growth as a consequence of ectopic expression of the multilineage colony-stimulating factor gene in hematopoietic progenitor cells. The rate at which the second event occurs is more than 3 orders of magnitude higher in precursor cell lines (FDC-P1 or FDC-P2) than in stem cell lines (FDC-Pmix). Autonomous, but not density-dependent, growth is tightly coupled to tumorigenicity in precursor cells; however, neither growth-factor-independent nor autonomously growing stem cell lines are tumorigenic.

Aberrant expression of the multi-CSF gene in hematopoietic precursor and stem cell lines initiates leukemogenic progression

Tumorigenesis of hemopoietic cells and acquisition of factor independence as a consequence of aberrant growth factor release are closely correlated. In previous work we were able to dissect two stages leading to growth factor autonomy of cells: the first step requires the secretion of the constitutively expressed CSF gene product and extracellular interaction with its cognate receptor. This requirement for external stimulation is abrogated by a second step. We were interested in characterizing the parameters that influence the conversion from nonautonomous to autonomous growth properties of hematopoietic precursor cells. The frequency with which this alteration occurs varies and correlates with the level of growth factor production. However, a significant increase of CSF production accompanying the progression to autonomy could not be detected. We thus conclude that there is no direct link between level of CSF production and acquisition of true autonomy but an indirect influence enhancing the frequency of genetic alteration(s) that lead to growth autonomy. Lang et al. have suggested that the acquisition of autonomous growth occurs due to internal receptor-ligand interaction. Indeed, Keating and Williams have claimed that PDGF may react with an intracellular PDGF receptor resulting in autocrine stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Progress in T cell biology

We outline recent work in our laboratories on thymus progenitors, lineages within the thymus, interactions between regulatory and effector lymphocytes, splitting the CD4 (T4) T cell subset, and Ir and Is genes. We highlight the possibilities for future research opened up by the demonstration that certain marrow-derived cell lines can repopulate thymic lobes in culture, and also the deep insight into the logical structure of the lymph node provided by our ability to make an exact comparison between two-cell-type and three-cell-type immunoregulatory clusters.

Changes in minor transcripts from the alpha 1 and beta maj globin and glutathione peroxidase genes during erythropoiesis

We have analysed the transcriptional regulation of the murine alpha 1 and beta maj globin genes and the glutathione peroxidase (GSHPx) gene, which are all highly expressed during erythropoiesis. The levels of minor RNAs compared to the major message were monitored throughout differentiation within the erythroid lineage. For each gene, upstream transcripts arise from distinct clusters of sites which are regulated differently during differentiation: some occur only during early erythropoiesis, some occur early and persist to the terminal stages, while others accumulate later and roughly in parallel with the main RNA transcript. In addition, opposite strand transcripts from the GSHPx gene were found in increasing amounts during later stages of erythropoiesis. The initiation sites for specific subsets of these minor transcripts lie close to sequences known to be involved in globin gene regulation (i.e. the TATA, CAAT and the CACCCT boxes) or other conserved sequences; others lie close to developmentally regulated DNase I hypersensitive sites around the globin and GSHPx genes.