Critical period plasticity of axonal arbors of layer 2/3 pyramidal neurons in rat somatosensory cortex: layer-specific reduction of projections into deprived cortical columns.

We examined the effect of whisker trimming during early postnatal development on the morphology of axonal arbors in rat somatosensory cortex. Axonal arbors from populations of layer 2/3 pyramidal neurons in the D2 column were labeled by lentivirus-mediated expression of green fluorescent protein. Axonal projection patterns were compared between untrimmed control animals and animals with all whiskers in A-, B-, and C-rows trimmed (D- and E-rows left intact) from postnatal days 7 to 15 (termed from here on DE-pairing). Control animals had approximately symmetrical horizontal projections toward C- and E-row columns in both supra- and infragranular layers. Following DE-pairing, the density of axons in supragranular layers projecting from the labeled neurons in the D2 column was higher in E- than in C-row columns. This asymmetry resulted primarily from a reduction in projection density toward the deprived C-row columns. In contrast, no change was observed in infragranular layers. The results indicate that DE-pairing during early postnatal development results in reduced axonal projection from nondeprived into deprived columns and that cortical neurons are capable of structural rearrangements at subsets of their axonal arbors.

Mutagenesis reveals a role for ABP/GRIP binding to GluR2 in synaptic surface accumulation of the AMPA receptor.

We studied the role of PDZ proteins GRIP, ABP, and PICK1 in GluR2 AMPA receptor trafficking. An epitope-tagged MycGluR2 subunit, when expressed in hippocampal cultured neurons, was specifically targeted to the synaptic surface. With the mutant MycGluR2delta1-10, which lacks the PDZ binding site, the overall dendritic intracellular transport and the synaptic surface targeting were not affected. However, over time, Myc-GluR2delta1-10 accumulated at synapses significantly less than MycGluR2. Notably, a single residue substitution, S880A, which blocks binding to ABP/GRIP but not to PICK1, reduced synaptic accumulation to the same extent as the PDZ site truncation. We conclude that the association of GluR2 with ABP and/or GRIP but not PICK1 is essential for maintaining the synaptic surface accumulation of the receptor, possibly by limiting its endocytotic rate.

Novel anchorage of GluR2/3 to the postsynaptic density by the AMPA receptor-binding protein ABP.

We report the cloning of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor-binding protein (ABP), a postsynaptic density (PSD) protein related to glutamate receptor-interacting protein (GRIP) with two sets of three PDZ domains, which binds the GluR2/3 AMPA receptor subunits. ABP exhibits widespread CNS expression and is found at the postsynaptic membrane. We show that the protein interactions of the ABP/GRIP family differ from the PSD-95 family, which binds N-methyl-D-aspartate (NMDA) receptors. ABP binds to the GluR2/3 C-terminal VKI-COOH motif via class II hydrophobic PDZ interactions, distinct from the class I PSD-95-NMDA receptor interaction. ABP and GRIP also form homo- and heteromultimers through PDZ-PDZ interactions but do not bind PSD-95. We suggest that the ABP/GRIP and PSD-95 families form distinct scaffolds that anchor, respectively, AMPA and NMDA receptors.

The AMPA receptor GluR2 C terminus can mediate a reversible, ATP-dependent interaction with NSF and alpha- and beta-SNAPs.

In this study, we demonstrate specific interaction of the GluR2 alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptor subunit C-terminal peptide with an ATPase N-ethylmaleimide-sensitive fusion protein (NSF) and alpha- and beta-soluble NSF attachment proteins (SNAPs), as well as dendritic colocalization of these proteins. The assembly of the GluR2-NSF-SNAP complex is ATP hydrolysis reversible and resembles the binding of NSF and SNAP with the SNAP receptor (SNARE) membrane fusion apparatus. We provide evidence that the molar ratio of NSF to SNAP in the GluR2-NSF-SNAP complex is similar to that of the t-SNARE syntaxin-NSF-SNAP complex. NSF is known to disassemble the SNARE protein complex in a chaperone-like interaction driven by ATP hydrolysis. We propose a model in which NSF functions as a chaperone in the molecular processing of the AMPA receptor.

Viral vectors: a wide range of choices and high levels of service.

Viruses are intracellular parasites with simple DNA or RNA genomes. Virus life revolves around three steps: infection of a host cell, replication of its genome within the host cell environment, and formation of new virions; this process is often but not always associated with pathogenic effects against the host organism. Since the mid-1980s, the main goal of viral vectorology has been to develop recombinant viral vectors for long-term gene delivery to mammalian cells, with minimal associated toxicity. Today, several viral vector systems are close to achieving this aim, providing stable transgenic expression in many different cell types and tissues. Here we review application characteristics of four vector systems, derived from adeno-associated viruses, adenoviruses, retroviruses and herpes simplex virus-1, for in vivo gene delivery. We discuss the transfer capacity of the expression vectors, the stability of their transgenic expression, the tropism of the recombinant viruses, the likelihood of induction of immunotoxicity, and the ease (or difficulty) of the virus production. In the end, we discuss applications of these vectors for delivery of three molecular systems for conditional mutagenesis, two for inducible transcriptional control of transgenic expression (the tet and the dimerizer systems), and the third one for inducible control of endogenous gene expression based on RNA interference.

PICK1 targets activated protein kinase Calpha to AMPA receptor clusters in spines of hippocampal neurons and reduces surface levels of the AMPA-type glutamate receptor subunit 2.

The PICK1 protein interacts in neurons with the AMPA-type glutamate receptor subunit 2 (GluR2) and with several other membrane receptors via its single PDZ domain. We show that PICK1 also binds in neurons and in heterologous cells to protein kinase Calpha (PKCalpha) and that the interaction is highly dependent on the activation of the kinase. The formation of PICK1-PKCalpha complexes is strongly induced by TPA, and PICK1-PKCalpha complexes are cotargeted with PICK1-GluR2 complexes to spines, where GluR2 is found to be phosphorylated by PKC on serine 880. PICK1 also reduces the plasma membrane levels of the GluR2 subunit, consistent with a targeting function of PICK1 and a PKC-facilitated release of GluR2 from the synaptic anchoring proteins ABP and GRIP. This work indicates that PICK1 functions as a targeting and transport protein that directs the activated form of PKCalpha to GluR2 in spines, leading to the activity-dependent release of GluR2 from synaptic anchor proteins and the PICK1-dependent transport of GluR2 from the synaptic membrane.

Differential downregulation of protein kinase C isoforms in spreading depression.

Spreading depression (SD) is a propagating depolarization of populations of neurons induced by intense electrical, chemical, or mechanical stimulation, which has been proposed to be an important mechanism in the aura of migraine. SD is characterized by a transient loss of synaptic transmission and thus may involve signal transduction mechanisms known to modulate synaptic strength. To examine the underlying pathophysiological molecular mechanisms of SD, we analyzed the regulation of eight protein kinase C (PKC) isoforms by immunoblot during SD induced by a high-intensity stimulus of synaptic afferents in the CA1 region of hippocampal slices. We observed a downregulation of the conventional (alpha, beta I, beta II, gamma) and the novel (delta, epsilon, eta) PKC isoforms in SD, but no change in the atypical isozyme (zeta). The coordinate downregulation of multiple PKC isoforms may be important in the functional depression of neuronal activity in SD. In contrast, the atypical zeta, and its constitutively active fragment PKM zeta, is a specific PKC isozyme that has been implicated in the maintenance of long-term potentiation (LTP) and long-term depression (LTD), widely studied models for the mechanism of memory. The stability of PKC zeta and PKM zeta in SD indicates that a molecular mechanism for the maintenance of LTP/ LTD is relatively resistant to alterations that occur during pathophysiologically large ionic fluxes. This result could help to explain the retention of information stored in the cortex despite the massive release of excitatory neurotransmitter and neuronal depolarization that may occur during the migrainous aura.

Evidence for a new, high-molecular weight isoform of protein kinase C in rat hippocampus.

We describe a new form of protein kinase C (PKC) with a molecular weight of 97 kDa, higher than the known forms of vertebrate PKC. This putative new high-molecular weight isoform, which we are calling PKC (HMW), is increased in the membrane fraction either upon application of phorbol esters or with afferent synaptic stimulation of Schaffer collaterals in hippocampal slices. The protein cross-reacts on immunoblot with affinity-purified polyclonal antiserum raised against a peptide derived from the carboxy-terminus of PKC eta; it does not cross-react, however, with antiserum against the amino-terminal region of PKC eta. In the tissues examined, PKC(HMW) is localized primarily in brain, in contrast to PKC eta, which is found predominantly in lung and skin.

[Rehabilitation of patients with brain stem damage]. / Rehabilitering av pasienter med hjernestammeskade.

We describe seven patients with serious brain stem damage who were admitted to Sunnaas Rehabilitation Hospital over a period of two years (1989-91). Our patients had quadriplegia and anarthria with some or completely preserved cognitive function. They experienced varying degrees of restitution, but all remained severely impaired. Important areas for rehabilitation include communication, alimentation, mobility, emotional reactions, medical complications and daily living arrangements. Severely impaired patients can enhance their quality of life by use of technical devices. Minimal motor function is necessary to control a switch, but preserved cognitive function is essential.

[Urinary problems among patients with stroke. Are these problems underestimated?]. / Vannlatingsproblemer hos hjerneslagpasienter. Blir problemene viet nok oppmerksomhet?

The article, based on a survey and a study of the literature, focuses on the problems of urinary disorders in patients who have suffered a stroke. The incidence of incontinence and other urination disorders was studied upon admission and six weeks later in ten stroke patients admitted consecutively to a hospital for rehabilitation. The results of the present study agreed with those of other studies, indicating that urination disorders, especially motoric urge incontinence, are common among stroke patients. The literature indicates that urinary incontinence has a negative influence on the rehabilitation process. Therefore the rehabilitation team should be particularly aware of such problems, and carry out both diagnostic and therapeutic procedures.

[Rehabilitation after stroke. Programs at the Sunnaas hospital]. / Rehabilitering etter hjerneslag. Dagens tilbud ved Sunnaas sykehus.

The article describes the rehabilitation programmes for stroke patients at Sunnaas Hospital, a Norwegian university hospital for rehabilitation. Patients with complex and less frequent problems following a cerebrovascular accident can attend this third line hospital for primary or secondary rehabilitation. In addition, special short-term programmes are offered to assess the potentials for rehabilitation, competence for a driver's licence, vocational ability and swallowing problems, as well as to judge the need for technical aids for communication, mobility and management of the surroundings. The various programmes are described in detail. During 1996 a total of 306 stroke patients, median age 57 years, attended the hospital. The hospital aims to continue to be a highly specialized centre for stroke patients, also in the future, with different kinds of comprehensive and multidisciplinary rehabilitation programmes for these patients.

[Automobile driving after a brain injury]. / Bilkjøring etter hjerneskade.

BACKGROUND: Little is known about driving fitness after brain damage. MATERIAL AND METHODS: The present study describes 62 brain injured patients, 36 with cerebral vascular accidents, 15 with traumatic brain injuries, and 11 with other neurological diseases, mean age 50 years, who after thorough assessment had been found fit enough for driving a car. 15 months later they were sent a questionnaire about their driving behaviour and skills. RESULTS: A higher number of traffic incidents were found after brain injury, but the difference was not significant. Patients with traumatic brain injury had a significantly higher number of traffic incidents post-injury than patients with stroke. A majority of those involved in incidents were young males with traumatic brain injury, who had deficits in cognitive executive functions. INTERPRETATION: Patients with traumatic brain injuries seem to need special attention when assessed for driving. Time to follow-up is too short for the results to be conclusive for the whole material of brain-injured patients. Further studies should be conducted.

Protein synthesis-dependent formation of protein kinase Mzeta in long-term potentiation.

The maintenance of long-term potentiation (LTP) in the CA1 region of the hippocampus has been reported to require both a persistent increase in phosphorylation and the synthesis of new proteins. The increased activity of protein kinase C (PKC) during the maintenance phase of LTP may result from the formation of PKMzeta, the constitutively active fragment of a specific PKC isozyme. To define the relationship among PKMzeta, long-term EPSP responses, and the requirement for new protein synthesis, we examined the regulation of PKMzeta after sub-threshold stimulation that produced short-term potentiation (STP) and after suprathreshold stimulation by single and multiple tetanic trains that produced LTP. We found that, although no persistent increase in PKMzeta followed STP, the degree of long-term EPSP potentiation was linearly correlated with the increase of PKMzeta. The increase was first observed 10 min after a tetanus that induced LTP and lasted for at least 2 hr, in parallel with the persistence of EPSP enhancement. Both the maintenance of LTP and the long-term increase in PKMzeta++ were blocked by the protein synthesis inhibitors anisomycin and cycloheximide. These results suggest that PKMzeta is a component of a protein synthesis-dependent mechanism for persistent phosphorylation in LTP.

Dominance of the lurcher mutation in heteromeric kainate and AMPA receptor channels.

Homomeric glutamate receptor (GluR) channels become spontaneously active when the last alanine residue within the invariant SYTANLAAF-motif in the third membrane segment is substituted by threonine. The same mutation in the orphan GluRdelta2 channel is responsible for neurodegeneration in "Lurcher" (Lc) mice. Since most native GluRs are composed of different subunits, we investigated the effect of an Lc-mutated subunit in heteromeric kainate and AMPA receptors expressed in HEK293 cells. Kainate receptor KA2 subunits, either wild type or carrying the Lc mutation (KA2(Lc)), are retained inside the cell but are surface-expressed when assembled with GluR6 subunits. Importantly, KA2(Lc) dominates the gating of KA2(Lc)/GluR6(WT) channels, as revealed by spontaneous activation and by slowed desensitization and deactivation kinetics of ligand-activated whole-cell currents. Moreover, the AMPA receptor subunit GluR-B(Lc)(Q) which forms spontaneously active homomeric channels with rectifying current-voltage relationships, dominates the gating of heteromeric GluR-B(Lc)(Q)/GluR-A(R) channels. The spontaneous currents of these heteromeric AMPAR channels show linear current-voltage relationships, and the ligand-activated whole-cell currents display slower deactivation and desensitization kinetics than the respective wild-type channels. For heteromeric Lc-mutated kainate and AMPA receptors, the effects on kinetics were reduced relative to the homomeric Lc-mutated forms. Thus, an Lc-mutated subunit can potentially influence heteromeric channel function in vivo, and the severity of the phenotype will critically depend on the levels of homomeric GluR(Lc) and heteromeric GluR(Lc)/GluR(WT) channels.

[Acupuncture therapy in stroke during the subacute phase. A randomized controlled trial]. / Akupunkturbehandling ved hjerneslag i subakutt fase. En randomisert kontrollert studie.

The aim of this study was to investigate whether acupuncture treatment, if given to stroke patients in subacute phase in addition to rehabilitation would influence motor function, activity of daily living (ADL) and quality of life. After obtaining informed consent, 45 patients (median age 57 years) were randomised into a control group (n = 21) and an acupuncture group (n = 24). Median time from onset of stroke to inclusion in the study was 40 days. The inclusion criterion was hemiparesis following a first-ever stroke. When included and six weeks later all patients were evaluated by three measurement systems: the Motor Assessment Scale for stroke patients, Sunnaas Index of ADL and Nottingham Health Profile. All patients underwent individually adapted rehabilitation therapy. The patients in the treatment group were given classical acupuncture three to four times a week for six weeks, each session lasting 20-30 minutes. Both groups improved significantly in motor function and ADL. However, improvement was significantly greater among the acupuncture group than among the controls. Only the acupuncture group rated a significantly improved quality of life. Our results indicate that acupuncture gives an additive therapeutic benefit when given to stroke patients during their rehabilitation programme in the subacute phase.

A one year follow-up study on the effects of acupuncture in the treatment of stroke patients in the subacute stage: a randomized, controlled study.

OBJECTIVE: We recently reported that acupuncture treatment of stroke patients in the subacute stage gave additive therapeutic benefit. The purpose of the present study was to determine, approximately one year after discharge from the rehabilitation hospital, whether the group differences still remained. DESIGN: The patients were randomized into two groups: one acupuncture group and one control group, considering gender and side of hemispheral localization of lesion. With regard to the main parameters the groups were comparable at baseline. SETTING: Initially, 45 stroke patients admitted to Sunnaas Rehabilitation Hospital were included in the study: median 40 days post stroke. SUBJECTS: Forty-one of the patients were available one year after the treatment period: 21 patients in the acupuncture group and 20 controls. INTERVENTION: All subjects received an individually adapted, multidisciplinary rehabilitation programme. The acupuncture group received additional treatment with classical acupuncture for 30 min three to four times weekly for six weeks. MAIN OUTCOME MEASURES: The patients were evaluated at inclusion, after six weeks and approximately 12 months after discharge from the rehabilitation hospital. The Motor Assessment Scale (MAS) for stroke patients, Sunnaas Index of Activity of Daily Living (ADL) and Nottingham Health Profile (NHP) were used. In addition, the social situations of the patients were recorded at one year follow-up. RESULTS: The results show that the acupuncture group improved significantly more than the controls, both during the treatment period of six weeks, and even more during the following year, both according to MAS, ADL, NHP and the social situation. CONCLUSION: Although the mechanism of the effects is debatable, there seems to be a positive long-term effect of acupuncture given in the subacute stage post stroke.

Persistent activation of the zeta isoform of protein kinase C in the maintenance of long-term potentiation.

Long-term potentiation in the CA1 region of the hippocampus, a model for memory formation in the brain, is divided into two phases. A transient process (induction) is initiated, which then generates a persistent mechanism (maintenance) for enhancing synaptic strength. Protein kinase C (PKC), a gene family of multiple isozymes, may play a role in both induction and maintenance. In region CA1 from rat hippocampal slices, most of the isozymes of PKC translocated to the particulate fraction 15 sec after a tetanus. The increase of PKC in the particulate fraction did not persist into the maintenance phase of long-term potentiation. In contrast, a constitutively active kinase, PKM, a form specific to a single isozyme (zeta), increased in the cytosol during the maintenance phase. The transition from translocation of PKC to formation of PKM may help to explain the molecular mechanisms of induction and maintenance of long-term potentiation.

[Videofluoroscopy in the examination of swallowing disorders. A useful method for evaluation of rehabilitation]. / Videofluoroskopi for undersøkelse av svelgevansker. En nyttig undersøkelsesmetode innen rehabilitering.

This article presents a protocol for videofluoroscopy based upon the literature and on four years of practical experience in a rehabilitation hospital from evaluation and treatment of dysphagia in patients with cerebral vascular and/or traumatic head injury. The protocol includes a description of clinical evaluation, necessary equipment and personnel. It also describes the types of food and liquids used, the positioning of the patient, the compensatory and therapeutic techniques which may be tested during the study, and the evaluation and reporting of results. During rehabilitation, patients with swallowing disorders can receive specific and practical advice on food intake, based on the results of videofluoroscopy.

[Acupuncture in stroke]. / Akupunktur ved hjerneslag.

In 1995 we reported that acupuncture treatment of stroke patients in the subacute stage resulted in added therapeutic benefit. The purpose of the present study was to determine, one year after discharge from the rehabilitation centre, whether the treatment continued to have effect. Initially, 45 stroke patients were included in the study; median 40 days post stroke. The patients were randomized into two groups; one acupuncture group and one control group, taking into considering the patients' sex and the actual site of the lesion. All subjects received an individually adapted, multidisciplinary rehabilitation programme. The acupuncture group received additional treatment with classical acupuncture for six weeks. The patients were thereafter given individual treatment at the rehabilitation centre and then under the primary health care service. 41 of the patients were available for further study one year after treatment ended; 21 patients from the acupuncture group and 20 from the control group. The results show that there was a significantly greater improvement in the acupuncture group than in the control group, both during the six-week treatment period, and even more so during the following year. These assessments were based on the Motor Assessment Scale, the Sunnaas Index of Daily Living (ADL), the Nottingham Health Profile and the patients' social circumstances.