Microencapsulated Bovine Chromaffin Cells In Vitro: Effect of Density and Coseeding with a NGF-Releasing Cell Line

Immobilization of discrete cell clusters within a partially crosslinked matrix prevents reaggregation of primary tissues and may provide a means for long-term maintenance of encapsulated cells. Dissociated bovine adrenal chromaffin (BAC) cells were suspended throughout crosslinked polyanionic microspheres previously shown to be selectively permeable. Microcapsules approximately 500 µm in diameter were seeded with: 1) three different densities of BAC cells; and 2) BAC cells suspended in Matrigel® or coseeded with a genetically modified nerve growth factor (NGF)- releasing fibroblast cell line. Each group was analyzed in vitro at 1, 4 and 8 weeks for spontaneous and potassium-evoked release of catecholamines, and maintained in vitro for up to 12 weeks for morphological observations. Over time, release of norepinephrine (NE) and epinephrine (EPI) diminished, while dopamine (DA) remained constant from the monoseeded capsules. In the coseeded group, an increase in potassium-evoked release of DA was observed from 1 to 4 weeks, and remained at that level up to 8 weeks. Encapsulated chromaffin cells retained a rounded morphology typical of undifferentiated cells. Intact chromaffin cells with well preserved and abundant secretory granules were observed ultrastructurally after 4 weeks in vitro. Small neurites from the chromaffin cells in the coseeded group were observed at 4 weeks with light microscopy, and up to 12 weeks with electron microscopy. Under static incubation conditions, 1 mM D-amphetamine resulted in a significant increase in the output of NE and DA from the coseeded capsules 8 weeks postimplantation, as compared to microcapsules loaded with chromaffin cells alone. Encapsulation within an immobilization matrix allows manipulation of the internal environment, thereby providing the ability to pre-treat cells with various factors in a non-invasive manner, which may enhance long-term cellular viability

Multiplexed, High Density Electrophysiology with Nanofabricated Neural Probes

Extracellular electrode arrays can reveal the neuronal network correlates of behavior with single-cell, single-spike, and sub-millisecond resolution. However, implantable electrodes are inherently invasive, and efforts to scale up the number and density of recording sites must compromise on device size in order to connect the electrodes. Here, we report on silicon-based neural probes employing nanofabricated, high-density electrical leads. Furthermore, we address the challenge of reading out multichannel data with an application-specific integrated circuit (ASIC) performing signal amplification, band-pass filtering, and multiplexing functions. We demonstrate high spatial resolution extracellular measurements with a fully integrated, low noise 64-channel system weighing just 330 mg. The on-chip multiplexers make possible recordings with substantially fewer external wires than the number of input channels. By combining nanofabricated probes with ASICs we have implemented a system for performing large-scale, high-density electrophysiology in small, freely behaving animals that is both minimally invasive and highly scalable

P. Aebischer Transplantation of Polymer Encapsulated Neurotransmitter Secreting Cells: Effect of the Encapsulation Technique

Deficits associated with neurological diseases may be improved by the transplantation Mammalian cells survive in an immunoincompatible host if they remain separated by a semipermeable membrane which allows transport of low molecular weight solutes, such as nutrients, but prevents the inward diffusion of both the humoral or cellular elements of the immune system. Transplantation of polymer-encapsulated endocrine tissue also allows the release of hormones which are regulated by humoral signals from the host environment. Immunoisolation using a permselective membrane has been studied with a variety of endocrine tissue

Central nervous system delivery of recombinant ciliary neurotrophic factor by polymer encapsulated differentiated C2C12 myoblasts.

Neurotrophic factors hold promise for the treatment of neurodegenerative diseases. Intrathecal transplantation of polymer encapsulated cell lines genetically engineered to release neurotrophic factors provides a means to deliver them continuously behind the blood-brain barrier. Long-term delivery, however, may benefit from the use of conditionally mitotic cells to avoid the overgrowth observed with continuously dividing cell lines. Myoblast lines have all the advantages of dividing cell lines, i.e., unlimited availability, possibility for in vitro screening for the presence of pathogens, suitability for stable gene transfer and clonal selection. Furthermore they can be differentiated into a nonmitotic stage upon exposure to low-serum-containing medium. In this study, mouse C2C12 myoblasts were transfected with a pNUT expression vector containing the human ciliary neurotrophic factor (CNTF) gene. hCNTF expression and bioactivity were demonstrated by Northern blot, ELISA assay, and measurement of choline acetyltransferase (ChAT) activity in embryonic spinal cord motor neuron cultures. One C2C12 clone was found to secrete 200 ng of CNTF/10(6) cells per day. The rate of secretion of hCNTF was not altered upon differentiation of C2C12 myoblasts. A bromodeoxyuridine (BrdU) proliferation assay indicated that approximately 12% of the myoblasts continue to divide after 4 days in low-serum-containing medium. The presence of the herpes simplex thymidine kinase gene (HSV-tk) in the expression vector, however, provides a way to eliminate these dividing myoblasts upon exposure to ganciclovir, therefore increasing the safety of the encapsulation technology using established cell lines. Encapsulated hCNTF-C2C12 cells can partially rescue motor neurons from axotomy-induced cell death. In adult rats, intrathecal implantation of encapsulated hCNTF-C2C12 cells or control C2C12 confirmed the long-term survival of these cells and their potential use as a source of neurotophic factors for the treatment of neurodegenerative diseases

Clonidine for attention-deficit/hyperactivity disorder: II. ECG changes and adverse events analysis

OBJECTIVE: To examine the safety and tolerability of clonidine used alone or with methylphenidate in children with attention-deficit/hyperactivity disorder (ADHD). METHOD: In a 16-week multicenter, double-blind trial, 122 children with ADHD were randomly assigned to clonidine (n = 31), methylphenidate (n = 29), clonidine and methylphenidate (n = 32), or placebo (n = 30). Doses were flexibly titrated up to 0.6 mg/day for clonidine and 60 mg/day for methylphenidate (both with divided dosing). Groups were compared regarding adverse events and changes from baseline to week 16 in electrocardiograms and vital signs. RESULTS: There were more incidents of bradycardia in subjects treated with clonidine compared with those not treated with clonidine (17.5% versus 3.4%, p =.02), but no other significant group differences regarding electrocardiogram and other cardiovascular outcomes. There were no suggestions of interactions between clonidine and methylphenidate regarding cardiovascular outcomes. Moderate or severe adverse events were more common in subjects on clonidine (79.4% versus 49.2%, p =.0006) but not associated with higher rates of early study withdrawal. Drowsiness was common on clonidine, but generally resolved by 6 to 8 weeks. CONCLUSIONS: Clonidine, used alone or with methylphenidate, appears safe and well tolerated in childhood ADHD. Physicians prescribing clonidine should monitor for bradycardia and advise patients about the high likelihood of initial drowsiness. Copyright 2008 © American Academy of Child and Adolescent Psychiatry

Relationships among relational communication processes and consultation outcomes for students with attention deficit hyperactivity disorder

Consultation has been shown to be an effective means to deliver school-based psychological services. The purpose of this study was to link patterns of consultant and teacher verbal interactions to consultation outcomes. Relational communication (Rogers & Escudero, 2004) was the research perspective taken, and the source of the consultation interviews was a large-scale assessment and intervention study of students with attention deficit hyperactivity disorder. Participants were five consultants, 42 teachers, and 42 elementary school students who were diagnosed with attention deficit hyperactivity disorder. The initial consultation interview for each case was coded using the Rogers and Farace (1975) coding system. Variables reflecting the nature of interpersonal influence within consultation - domineeringness and dominance - were calculated for consultants and teachers. Teacher dominance (successful influence) was associated with (a) teacher ratings of intervention effectiveness (r =.48), (b) teacher ratings of student progress-to-target behavior (r = .33), and (c) consultant observations of teachers\u27 treatment integrity (t = -.32). Results suggest that greater attention be paid to how teachers contribute to the process and content of consultation. Copyright 2007 by the National Association of School Psychologists