Microglial contribution to synaptic uptake in the prefrontal cortex in schizophrenia.

Microglia in human post-mortem tissue in schizophrenia patients' brains engulf synaptic material, but not differently to age-matched non-neurological control brains. Also, schizophrenia brains display similar levels of microgliosis to control brains.

Posterior wall acetabular fracture fixation: A mechanical analysis of fixation methods.

Stable, anatomical fixation of acetabular fractures gives the best chance of successful outcome, while penetration of the acetabular articular surface with screws is associated with poor outcomes. Spring plates are an alternative to interfragmentary lag screws when penetration is a concern. A mechanical study comparing fracture stability and construct stiffness of three fixation methods for posterior wall acetabular fractures with transverse comminutions was performed. The three fixation methods tested were a posterior wall rim plate, a posterior wall buttress plate with separate lag screws and a posterior wall plate with two spring plates. Nine samples were tested, three for each fixation method. Two-dimensional motion analysis was used to measure fracture fragment displacement and construct stiffness. After two 6000 cycle-loading protocols, to a maximum 1.5 kN, the mean fracture displacement was 0.154 mm for the rim plate model, 0.326 mm for the buttress plate and 0.254 mm for the spring plate model. Mean maximum displacement was significantly less for the rim plate fixation than the buttress plate (p = 0.015) and spring plate fixation (p = 0.02). The rim plate was the stiffest construct 10,962 N/mm, followed by the spring plate model 5637 N/mm and the buttress plate model 4882 N/mm. Based on data obtained in this study, where possible a rim plate with interfragmentary lag screws should be used for isolated posterior wall fractures as this is the stiffest and most stable construct. When this method is not possible, spring plate fixation is a safe and a superior alternative to a posterior buttress plate method.

The effect of type of afferent feedback timed with motor imagery on the induction of cortical plasticity.

A peripherally generated afferent volley that arrives at the peak negative (PN) phase during the movement related cortical potential (MRCP) induces significant plasticity at the cortical level in healthy individuals and chronic stroke patients. Transferring this type of associative brain-computer interface (BCI) intervention into the clinical setting requires that the proprioceptive input is comparable to the techniques implemented during the rehabilitation process. These consist mainly of functional electrical stimulation (FES) and passive movement induced by an actuated orthosis. In this study, we compared these two interventions (BCIFES and BCIpassive) where the afferent input was timed to arrive at the motor cortex during the PN of the MRCP. Twelve healthy participants attended two experimental sessions. They were asked to perform 30 dorsiflexion movements timed to a cue while continuous electroencephalographic (EEG) data were collected from FP1, Fz, FC1, FC2, C3, Cz, C4, CP1, CP2, and Pz, according to the standard international 10-20 system. MRCPs were extracted and the PN time calculated. Next, participants were asked to imagine the same movement 30 times while either FES (frequency: 20Hz, intensity: 8-35mAmp) or a passive ankle movement (amplitude and velocity matched to a normal gait cycle) was applied such that the first afferent inflow would coincide with the PN of the MRCP. The change in the output of the primary motor cortex (M1) was quantified by applying single transcranial magnetic stimuli to the area of M1 controlling the tibialis anterior (TA) muscle and measuring the motor evoked potential (MEP). Spinal changes were assessed pre and post by eliciting the TA stretch reflex. Both BCIFES and BCIpassive led to significant increases in the excitability of the cortical projections to TA (F(2,22)=4.44, p=0.024) without any concomitant changes at the spinal level. These effects were still present 30min after the cessation of both interventions. There was no significant main effect of intervention, F(1,11)=0.38, p=0.550, indicating that the changes in MEP occurred independently of the type of afferent inflow. An afferent volley generated from a passive movement or an electrical stimulus arrives at the somatosensory cortex at similar times. It is thus likely that the similar effects observed here are strictly due to the tight coupling in time between the afferent inflow and the PN of the MRCP. This provides further support to the associative nature of the proposed BCI system.

Convergence of ipsi- and contralateral muscle afferents on common interneurons mediating reciprocal inhibition of ankle plantarflexors in humans.

Recent studies have shown that afferents arising from muscle receptors located on one side can affect the activity of muscles on the contralateral side. In animal preparations, evidence supports that afferent pathways originating from one limb converge onto interneurons mediating disynaptic reciprocal Ia inhibition of the opposite limb. This study was designed to investigate whether this pathway is similar in humans to that described in animals. Thirteen healthy volunteers participated in one of two experiments. In experiment 1, the effects of ipsilateral posterior tibial nerve (iPTN) stimulation were assessed on the reciprocal Ia inhibition of the contralateral soleus (cSOL) motoneuronal pool (n = 8). Across all participants, iPTN stimulation intensity was 1.69 ± 0.3 × Motor Threshold (MT) and contralateral common peroneal (cCPN) stimulation intensity was 0.86 ± 0.16 × MT. iPTN and cCPN stimulation were delivered separately or in combination and changes in the ongoing electromyography (EMG) quantified. In experiment 2, the amplitude of a test SOL H-reflex elicited by contralateral PTN (cPTN) stimulation was quantified following iPTN, cCPN or iPTN + cCPN nerve stimulation (n = 5). Intensities used during the H-reflex conditioning experiment were 1.79 ± 0.4 × MT for the iPTN stimulation and 0.88 ± 0.16 × MT for cCPN stimulation. Across all participants, the onset of the cSOL EMG suppression was 42 ± 4, 44 ± 3 and 44 ± 3 ms for iPTN, cCPN and iPTN + cCPN conditions, respectively. The inhibition from the combined iPTN and cCPN stimulation was significantly greater compared to the algebraic sum of their separate effects. When conditioning the cSOL H-reflex, the ISI between the test cPTN and the iPTN or cCPN stimulus was 5.4 ± 0.5 and 2.6 ± 0.5, respectively. The combined stimulation induced a significantly greater inhibition compared to their separate effects. These data provide evidence of convergence on common inhibitory interneurons by muscle afferents activated by iPTN and cCPN stimulation during sitting. Since the inhibition elicited by cCPN stimulation is known to be mediated by the disynaptic Ia inhibitory pathway, this suggests that the crossed inhibition of cSOL motoneurones elicited by muscle afferents from the ipsilateral plantarflexor muscles is at least partly mediated by Ia inhibitory interneurons in the contralateral human spinal cord. This is similar to what has been observed in the cat.

Percutaneous internal fixation of pelvic fractures.

BACKGROUND: Percutaneous internal fixation of pelvic fractures is increasing in popularity with multiple new techniques reported. OBJECTIVES: The purpose of this article is to outline the imaging, indication, planning, equipment, surgical technique and complications of these methods. METHODS: A review of the literature is provided and the techniques for anterior and posterior pelvic stabilisation are discussed. RESULTS: High-quality preoperative CT scans are essential in planning for this technique. The anterior internal fixator ("InFix") is an effective method for stabilising the anterior ring and should be usually used in conjunction with posterior fixation. Good technique avoids neurovascular injury, which can be a devastating complication. The retrograde anterior column screw (RACS) is a technique that can be used in most patients, although in smaller patients smaller screw diameters may be needed. The entry point for the screw is more lateral in women than men. Iliosacral screws (ISS) are an effective method of posterior stabilisation and can be placed using 2D or 3D fluoroscopy, computer navigation or CT navigation. CONCLUSION: Percutaneous fixation of pelvic fractures requires high-quality imaging and can be aided by computer navigation. Safe techniques are reproducible; however, not all patients and fracture patterns can be treated using these techniques.

[Percutaneous internal fixation of pelvic fractures. German version]. / Perkutane interne Fixation bei Beckenfrakturen.

BACKGROUND: Percutaneous internal fixation of pelvic fractures is increasing in popularity with multiple new techniques reported. OBJECTIVES: The purpose of this article is to outline the imaging, indication, planning, equipment, surgical technique and complications of these methods. METHODS: A review of the literature is provided and the techniques for anterior and posterior pelvic stabilization are discussed. RESULTS: High-quality preoperative CT scans are essential in planning for this technique. The anterior internal fixator ("InFix") is an effective method for stabilizing the anterior ring and should be usually used in conjunction with posterior fixation. Good technique avoids neurovascular injury, which can be a devastating complication. The retrograde anterior column screw (RACS) is a technique that can be used in most patients, although in smaller patients smaller screw diameters may be needed. The entry point for the screw is more lateral in women than men. Iliosacral screws (ISS) are an effective method of posterior stabilization and can be placed using 2D or 3D fluoroscopy, computer navigation or CT navigation. CONCLUSION: Percutaneous fixation of pelvic fractures requires high-quality imaging and can be aided by computer navigation. Safe techniques are reproducible; however, not all patients and fracture patterns can be treated using these techniques.

Cortical involvement in the StartReact effect.

The rapid release of prepared movements by a loud acoustic stimulus capable of eliciting a startle response has been termed the StartReact effect (Valls-Solé et al., 1999), and premotor reaction times (PMTs) of <70 ms are often observed. Two explanations have been given for these short latency responses. The subcortical storage and triggering hypothesis suggests movements that can be prepared in advance of a "go" signal are stored and triggered from subcortical areas by a startling acoustic stimulus (SAS) without cortical involvement. Alternatively, it has been hypothesized that the SAS can trigger movements from cortical areas through a faster pathway ascending from subcortical structures. Two experiments were designed to examine the possible role of the primary motor cortex in the StartReact effect. In Experiment 1, we used suprathreshold transcranial magnetic stimulation (TMS) during the reaction time (RT) interval to induce a cortical silent period in the contralateral primary motor cortex (M1). Thirteen participants performed 20° wrist extension movements as fast as possible in response to either a control stimulus (82 dB) or SAS (124 dB). PMTs for startle trials were faster than for control trials, while TMS significantly delayed movement onset compared to No TMS or Sham TMS conditions. In Experiment 2, we examined the StartReact effect in a highly cortically represented action involving speech of a consonant-vowel (CV) syllable. Similar to previous work examining limb movements, a robust StartReact effect was found. Collectively, these experiments provide evidence for cortical (M1) involvement in the StartReact effect.

Comparison of arthroscopic and MRI findings of osteochondral damage in knees.

Magnetic resonance imaging (MRI) scans are widely used in the assessment of knees, often prior to arthroscopic procedures. The reporting of osteochondral damage on MRI scans can be variable. The correlation between MRI reports of osteochondral damage and that found at arthroscopy is often inconsistent. A retrospective case-note review of a single-surgeon series of 175 arthroscopic procedures was performed. Eighty-three patients were included in the study. The remainder were excluded if an MRI scan had not been performed or had been performed more than 3-months before surgery. The condition of the articular cartilage demonstrated by MRI was compared to that found at arthroscopy. Data was analysed for presence and extent of osteochondral damage. Comparison between MRI and arthroscopy findings showed high specificity (90%) and negative predictive values (89%) for osteochondral damage but low sensitivity (46%). Cohen's kappa values < 0.2 revealed very poor correlation for the extent of damage. This study demonstrates MRI as a good identifier of osteochondral damage but an unreliable descriptor for such change.

Chronic haematogenous osteomyelitis in children: an unsolved problem.

From a global point of view, chronic haematogenous osteomyelitis in children remains a major cause of musculoskeletal morbidity. We have reviewed the literature with the aim of estimating the scale of the problem and summarising the existing research, including that from our institution. We have highlighted areas where well-conducted research might improve our understanding of this condition and its treatment.

Analysis of changes in optical fibers during arc-fusion splicing by use of quantitative phase imaging.

A non-interferometric imaging technique in conjunction with Abel inversion is used to directly and quantitatively examine the changes in optical fibers due to the heating produced during arc-fusion splicing as a function of fusion arc parameters. Phase images in the vicinity of a fusion splice are obtained using Quantitative Phase Microscopy, allowing the refractive-index change to be reconstructed with high spatial resolution. This simple, nondestructive method confirms that, for a fixed arc current, while the fusion time increases, the refractive-index of both fiber cores within the fusion region decreases in magnitude, the core region broadens, and the axial gradient decreases.

Stable marker gene transfer into human bone marrow stromal cells and their progenitors using novel herpesvirus saimiri-based vectors.

We have evaluated the ability of new herpesvirus saimiri (HVS)-based vectors to deliver a marker gene green fluorescent protein (GFP) into human bone marrow (BM) stromal cells and their progenitors. Stromal cells expanded from adherent layers of long-term BM cultures (LTC) were susceptible to HVS-based infection in a dose-dependent manner, and the efficiency of 94.8 +/- 2.0% was achieved using single exposure with HVS/EGFP vector at multiplicity of infection (moi) of approximately 50. Colony-forming unit-fibroblast (CFU-F) assay established the ability of HVS-based vectors to infect progenitors for bone marrow stroma fibroblasts and transfer the marker gene over multiple cell divisions in the absence of selective pressure. HVS was not toxic for stromal cells and progenitors and no viral replication was detected upon growth of modified stroma. On the basis these data, we believe that HVS-based constructs can offer a new opportunity for selective gene delivery into bone marrow stromal cells and progenitors. The ability of HVS to infect nondividing cells can be considered advantageous in the development of both ex vivo and in vivo strategies.

A herpesvirus saimiri-based gene therapy vector with potential for use in cancer immunotherapy.

The herpesvirus saimiri (HVS) genome has the capacity to incorporate large amounts of heterologous DNA and can be maintained episomally in many different human cell types. To evaluate the efficacy of HVS-mediated gene transfer into human hemopoietic cells, we investigated the ability of an HVS-based construct, carrying the enhanced green fluorescent protein (EGFP) and neomycin resistance genes, to transduce a variety of human hemopoietic cell lines and primary CD34+ cells. As measured by flow cytometry, the numbers of EGFP+ cells at 2 days postinfection differed between various cell types ranging, from 1.3% for KG1 cells to 56.8% for THP-1 cells. In addition, the expression of EGFP in Jurkat cells was retained at >95% per round of cell division over a period of 6 weeks (comparable with Epstein-Barr virus-derived gene therapy systems). Although the virus was not specifically disabled, no lytic viral mRNAs could be detected in transduced Jurkat cells, and infectious virus could not be detected by sensitive virus recovery assay. We also describe a simple centrifugation method that increases the efficiency of transduction by >100% in some cases and may be generally applicable to other herpesvirus-based vectors for ex vivo gene delivery. Using this technique, we were able to demonstrate a tropism for CD34+/CD14+ cells, transducing 30% of the population. These cells are known to give rise to dendritic cells (the most potent of the antigen-presenting cells), suggesting that the vector could be used to deliver DNA sequences encoding tumor antigens for cancer immunotherapy.

Specific oncolytic activity of herpesvirus saimiri in pancreatic cancer cells.

The potential use of oncolytic viruses in the treatment of cancer has been investigated for some time. A variety of agents have been studied, including some which appear to be selectively replication-competent in cancer cell lines. In this study, we have investigated the ability of herpesvirus saimiri to specifically lyse selected human cancer cell lines. Upon infection with a replication-competent virus carrying the EGFP reporter gene and a neomycin resistance marker, the pancreatic cancer lines MIAPACA and PANC-1 exhibited definite cytopathic effects. In contrast, the colonic carcinoma cell lines SW480 and HCT116 were phenotypically unaltered. In addition, stable cell lines could not be generated from PANC-1 infected cultures, in marked contrast to cultures of cells from other human tissues. Virus recovery assays demonstrated that all of the cell lines produced a small amount of virus post-infection, but that virus replication was minimal after 1 week in culture. In addition, treatment with acyclovir inhibited virus replication but paradoxically increased cytopathic effect. These data suggest that herpesvirus saimiri may have potential as an oncolytic agent for the treatment of pancreatic cancer.

Analysis of gene expression in a human cell line stably transduced with herpesvirus saimiri.

Herpesvirus saimiri (HVS) is the prototype gamma-2 herpesvirus; it has significant homology to the human gammaherpesviruses Kaposi's sarcoma-associated virus and Epstein-Barr virus and the murine gammaherpesvirus murine herpesvirus 68. HVS causes a persistent asymptomatic infection in its natural host, the squirrel monkey. Both subgroups A and C possess the ability to immortalize common marmoset T lymphocytes to interleukin-2-independent proliferation. However, only subgroup C is capable of transforming human, rabbit, and rhesus monkey lymphocytes in vitro. In addition, HVS can stably transduce a variety of human cell lines where the virus persists as a nonintegrating circular episome. In this study, we have developed a system in which the HVS DNA is stably maintained as a nonintegrated circular episome in the human lung carcinoma cell line A549. Virus production can be reactivated using chemical inducing agents, including tetradecanoyl phorbol acetate and n-butyrate, suggesting that the infection in human A549 cells is latent. To analyze virus gene expression in these stably transduced cells, Northern blot analysis was performed using a series of probes produced from restriction fragments spanning the entire coding region of the HVS genome. This demonstrated that an adjacent set of genes containing open reading frames (ORFs) 71 to 73 are expressed in this stably transduced cell line. Moreover, these genes are transcribed as a polycistronic mRNA species produced from a common promoter upstream of ORF 73. This model may serve as a useful tool in the further analysis of the role of ORFs 71 to 73 in gamma-2 herpesvirus latency.

Herpesvirus saimiri-based gene delivery vectors maintain heterologous expression throughout mouse embryonic stem cell differentiation in vitro.

In order to achieve a high efficiency of gene delivery into rare cell types like stem cells the use of viral vectors is presently without alternative. An ideal stem cell gene therapy vector would be able to infect primitive progenitor cells and sustain or activate gene expression in differentiated progeny. However, many viral vectors are inactivated when introduced in developing systems where cell differentiation occurs. To this end, we have developed a mouse in vitro model for testing herpesvirus saimiri (HVS)-based gene therapy vectors. We demonstrate here for the first time that HVS is able to infect totipotent mouse embryonic stem (ES) cells with high efficiency. We have transduced ES cells with a recombinant virus carrying the enhanced green fluorescent protein (EGFP) gene and the neomycin resistance gene (NeoR) driven by a CMV promoter and the SV40 promoter, respectively. ES cells maintain the viral episomal genome and can be terminally differentiated into mature haematopoietic cells. Moreover, heterologous gene expression is maintained throughout in vitro differentiation. Besides its obvious use in gene therapy, this unique expression system has wide ranging applications in studies aimed at understanding gene function and expression in cell differentiation and development.

Rates of spontaneous reactivation and aging of acetylcholinesterase in human erythrocytes after inhibition by organophosphorus pesticides.

The in vitro rates of spontaneous reactivation and aging in human erythrocyte acetylcholinesterase were studied after inhibition by a dimethoxy (R1R2) and diethoxy substituted (R1R2) organophosphate pesticide (OP) of general structure R1R2P(O)X. These have been compared with data for human plasma cholinesterase previously reported using a similar methodology. A significantly slower rate of aging for erythrocyte acetylcholinesterase was found compared to plasma cholinesterase, whether inhibited by dimethoxy or diethoxy substituted OPs. For diethoxy OPs the rate of spontaneous reactivation of the inhibited plasma enzyme was significantly slower than for the inhibited red cell enzyme. This acetylcholinesterase, and previously published plasma cholinesterase, data suggest that in practise a blood sample taken 30-40 h after significant acute OP exposure will still show inhibition in either plasma or erythrocyte cholinesterase when analysed, but that any inhibited plasma enzyme is more likely to be in the aged form. In contrast a substantial proportion of the erythrocyte acetylcholinesterase is found unaged and therefore sensitive to reactivation by oximes. Samples from an occupational exposure where depressions in plasma or erythrocyte cholinesterase activity from baseline measurements were reactivated ex vivo using the oxime 2-PAM support this hypothesis. These data also confirm that the plasma enzyme is a more sensitive than erythrocyte acetylcholinesterase as an indicator of OP exposure and thus the potential value of ex vivo oxime reactivation of erythrocyte acetylcholinesterase in a blood sample to indicate subclinical OP exposure may be limited. However, this study is too small to draw conclusions on the sensitivity of ex vivo oxime reactivation of acetylcholinesterase as a novel biomarker of excessive OP absorption. Given that there is a better relationship between anticholinergic symptoms and red cell acetylcholinesterase inhibition, and that the slower resynthesis rate of any aged or inhibited red cell enzyme may be interpretatively useful when venepuncture is delayed, it is suggested that red cell acetylcholinesterase activity does have a place in monitoring potential OP exposure.

The activation domain of herpesvirus saimiri R protein interacts with the TATA-binding protein.

The herpesvirus saimiri open reading frame (ORF) 50 produces two transcripts. The first is spliced, contains a single intron, and is detected at early times during the productive cycle, whereas the second is expressed later and is produced from a promoter within the second exon. Analysis of their gene products has shown that they function as sequence specific transactivators. In this report, we demonstrate that the carboxy terminus of ORF 50b contains an activation domain which is essential for transactivation. This domain contains positionally conserved hydrophobic residues found in a number of activation domains, including the herpes simplex virus VP16 and the Epstein-Barr virus R proteins. Mutational analysis of this domain demonstrates that these conserved hydrophobic residues are essential for ORF 50 transactivation capability. Furthermore, this domain is required for the interaction between the ORF 50 proteins and the basal transcription factor TATA-binding protein.

The open reading frame 57 gene product of herpesvirus saimiri shuttles between the nucleus and cytoplasm and is involved in viral RNA nuclear export.

The herpesvirus saimiri open reading frame (ORF) 57 is homologous to genes identified in all classes of herpesviruses. It has previously been shown to regulate gene expression through a posttranscriptional mechanism. We demonstrate in this report that the expression of the ORF 57 protein leads to the cytoplasmic accumulation of glycoprotein B and capsid mRNAs. We also demonstrate that ORF 57 has the ability to specifically bind viral RNA transcripts. Utilizing an interspecies heterokaryon assay, we show that ORF 57 has the ability to shuttle between the nucleus and the cytoplasm. Furthermore, we show that ORF 57 contains a relatively leucine-rich sequence which shares some homology with nuclear export signals (NES) found in a number of proteins with the ability to shuttle between the nucleus and the cytoplasm. Moreover, we demonstrate that the ORF 57 NES enables the nuclear export of a heterologous protein and that mutation of the conserved leucine residues contained within the ORF 57 NES signal abrogates the ability of the ORF 57 protein to shuttle between the nucleus and cytoplasm. These results suggest that ORF 57 is involved in mediating the nuclear export of viral transcripts.

Biomarkers in occupational volatile organic chemical exposure.

Evidence exists that in certain groups of workers exposed to volatile organic chemicals, there is subclinical renal damage and dysfunction. Also, there is activation of biological mechanisms that are suggested links between volatile organic chemical exposure and renal disease. Notably, the workers studied are employed in factories where exposures are considered controlled, with on-site professional health and safety management. Recent studies continue to indicate an increased risk of renal disease in those exposed to volatile organic chemicals.

The gene product encoded by ORF 57 of herpesvirus saimiri regulates the redistribution of the splicing factor SC-35.

The herpesvirus saimiri (HVS) gene product encoded by ORF 57 shares limited C-terminal similarity with herpes simplex virus 1 ICP27, a protein that has been demonstrated to be involved in the inhibition of host-cell splicing and is responsible for the redistribution of components of the spliceosome. It has previously been shown that ORF 57 can either activate or repress viral gene expression by a post-transcriptional mechanism. Furthermore, repression of gene expression by ORF 57 is dependent on the presence of an intron within the target gene coding region. In this report, it is shown that HVS infection results in the redistribution of the SC-35 splicing factor in the infected cell nucleus. Furthermore, the redistributed SC-35 colocalized with the ORF 57 protein product and expression of the protein alone was sufficient to cause the redistribution of the spliceosome components. These results suggest that the mechanism by which ORF 57 down-regulates expression of intron-containing genes involves the redistribution of the spliceosome complex.