The C-Band All-Sky Survey (C-BASS): Simulated parametric fitting in single pixels in total intensity and polarization

The cosmic microwave background (CMB) B-mode signal is potentially weaker than the diffuse Galactic foregrounds over most of the sky at any frequency. A common method of separating the CMB from these foregrounds is via pixel-based parametric-model fitting. There are not currently enough all-sky maps to fit anything more than the most simple models of the sky. By simulating the emission in seven representative pixels, we demonstrate that the inclusion of a 5 GHz data point allows for more complex models of low-frequency foregrounds to be fitted than at present. It is shown that the inclusion of the C-BASS data will significantly reduce the uncertainties in a number of key parameters in the modelling of both the galactic foregrounds and the CMB. The extra data allow estimates of the synchrotron spectral index to be constrained much more strongly than is presently possible, with corresponding improvements in the accuracy of the recovery of the CMB amplitude. However, we show that to place good limits on models of the synchrotron spectral curvature will require additional low-frequency data.

On the redshift distribution and physical properties of ACT-selected DSFGs

We present multi-wavelength detections of nine candidate gravitationally-lensed dusty star-forming galaxies (DSFGs) selected at 218GHz (1.4mm) from the ACT equatorial survey. Among the brightest ACT sources, these represent the subset of the total ACT sample lying in Herschel SPIRE fields, and all nine of the 218GHz detections were found to have bright Herschel counterparts. By fitting their spectral energy distributions (SEDs) with a modified blackbody model with power-law temperature distribution, we find the sample has a median redshift of z = 4.1 - 1.0 + 1.1 (68 per cent confidence interval), as expected for 218GHz selection, and an apparent total infrared luminosity of log 10 ( μ L IR / L ⊙ ) = 13.86 - 0.30 + 0.33 , which suggests that they are either strongly lensed sources or unresolved collections of unlensed DSFGs. The effective apparent diameter of the sample is μ d = 4.2 - 1.0 + 1.7 kpc , further evidence of strong lensing or multiplicity, since the typical diameter of dusty star-forming galaxies is 1.0-2.5 kpc. We emphasize that the effective apparent diameter derives from SED modelling without the assumption of optically thin dust (as opposed to image morphology). We find that the sources have substantial optical depth. ( τ = 4.2 - 1.9 + 3.7 ) to dust around the peak in the modified blackbody spectrum (λ _obs ⩽ 500μm), a result that is robust to model choice.

Scientific codes developed and used at GRS – Nuclear simulation chain

Over 60 technical experts of the reactor safety research division of the Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) gGmbH are developing and validating reliable methods and computer codes – summarized under the term nuclear simulation chain – for the safety-related assessment for all types of nuclear power plants (NPP) and other nuclear facilities considering the current state of science and technology. This nuclear simulation chain has to be able to simulate and assess all relevant physical processes and phenomena for all operating states and (severe) accidents. In the present contribution, the nuclear simulation chain developed and applied by GRS as well as selected examples of its application are presented. The latter demonstrate impressively the width of its scope and its performance. The GRS codes can be passed on request to other (national as well as international) organizations. This contributes to a worldwide increase of the nuclear safety standards. The code transfer is especially important for developing and emerging countries lacking the financial means and/or the necessary know-how for this purpose. At the end of this contribution, the respective course of action is described.

Randomised crossover trial of four nasal respiratory support systems for apnoea of prematurity in very low birthweight infants

BACKGROUND

Apnoea of prematurity (AOP) is a common problem in preterm infants which can be treated with various modes of nasal continuous positive airway pressure (NCPAP) or nasal intermittent positive pressure ventilation (NIPPV). It is not known which mode of NCPAP or NIPPV is most effective for AOP.

OBJECTIVE

To assess the effect of four NCPAP/NIPPV systems on the rate of bradycardias and desaturation events in very low birthweight infants.

METHODS

Sixteen infants (mean gestational age at time of study 31 weeks, 10 males) with AOP were enrolled in a randomised controlled trial with a crossover design. The infants were allocated to receive nasal pressure support using four different modes for 6 h each: NIPPV via a conventional ventilator, NIPPV and NCPAP via a variable flow device, and NCPAP delivered via a constant flow underwater bubble system. The primary outcome was the cumulative event rate of bradycardias (< or =80 beats per minute) and desaturation events (< or =80% arterial oxygen saturation), which was obtained from cardio-respiratory recordings.

RESULTS

The median event rate was 6.7 per hour with the conventional ventilator in NIPPV mode, and 2.8 and 4.4 per hour with the variable flow device in NCPAP and NIPPV mode, respectively (p value<0.03 for both compared to NIPPV/conventional ventilator). There was no significant difference between the NIPPV/conventional ventilator and the underwater bubble system.

CONCLUSION

A variable flow NCPAP device may be more effective in treating AOP in preterm infants than a conventional ventilator in NIPPV mode. It remains unclear whether synchronised NIPPV would be even more effective.

Bicarbonate-buffered ultrafiltration during pediatric cardiac surgery prevents electrolyte and acid-base balance disturbances

Pediatric cardiopulmonary bypass is still a challenge because of electrolyte disturbances and inflammation. Many investigations deal with different types of hemofiltration to reduce these potentially harmful side effects. We tested the hypothesis of whether bicarbonate-buffered hemofiltration of the priming solution minimizes electrolyte and acid-base disturbances during the initiation of cardiopulmonary bypass and whether bicarbonate-buffered hemofiltration performed during cardiopulmonary bypass could reduce cytokine levels. Twenty children younger than 2 years of age (mean age 166 ± 191 days; mean weight 6.42 ± 3.22 kg) scheduled for pediatric cardiac surgery with cardiopulmonary bypass were enrolled in this prospective clinical study. Cardiopulmonary bypass circuits were primed with a bicarbonate-buffered hemofiltration solution, gelatin and 1 unit of packed red blood cells. The priming was hemofiltered using an ultrahemofilter until approximately 1000 mL of ultrafiltrate was restored with the buffered solution. Further hemofiltration was performed throughout the whole bypass time, especially during rewarming. Blood gas analyses and inflammatory mediators were monitored during the operation. Blood gas analysis results after initiation of cardiopulmonary bypass and throughout the entire study remained within the physiologic ranges. Even potassium decreased from 4.0 ± 0.3 to 3.4 ± 0.4 mmol.l−1 after initiation of cardiopulmonary bypass. Plasma levels of tumor necrosis factor alpha decreased significantly (47 ± 44 vs. 24 ± 21 pg.mL−1) whereas complement factor C3a (5.0 ± 2.9 vs. 16.8 ± 6.6 ng.mL−1) and interleukin-6 (7.3 ± 15.2 vs. 110 ± 173 pg.mL−1) increased despite hemofiltration. In conclusion, this study shows that bicarbonate-buffered ultrafiltration is an efficient, simple and safe method for performing hemofiltration, both of the priming solution and during the entire bypass time. The use of a physiological restitution solution prevents electrolyte and acid-base balance disturbances. The elimination of inflammatory mediators seems to be as effective as other ultrafiltration methods.

Inflammation in Parkinsons Diseases and Other Neurodegenerative Diseases: Cause and Therapeutic Implications

Agents suppressing microglial activation are attracting attention as candidate drugs for neuroprotection in Parkinson s disease (PD): While different mechanisms including environmental toxins and genetic factors initiate neuronal damage in the substantia nigra and striatum in PD, there is unequivocal evidence that activation of neuroinflammatory cells aggravates this neurodegenerative process. It was shown that following an acute exposure to the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and other toxins the degenerative process continues for years in absence of the toxin. Reactive microglia has been observed in the substantia nigra of patients with PD, indicating that this inflammatory process might aggravate neurodegeneration. By releasing various kinds of noxious factors such as cytokines or proinflammatory molecules microglia may damage CNS cells. The stimuli triggering microgliosis in Parkinsonian syndromes are unknown so far: However, analysis of neuronal loss in PD patients shows that it is not uniform but that neurons containing neuromelanin (NM) are predominantly involved. We hypothesized that extraneuronal melanin might trigger microgliosis, microglial chemotaxis and microglial activation in PD with subsequent release of neurotoxic mediators. The addition of human NM to microglial cell cultures induced positive chemotactic effects, activated the pro-inflammatory transcription factor nuclear factor kappa B (NF-kappaB) via phosphorylation and degradation of the inhibitor protein kappaB (IkappaB), and led to an upregulation of TNF-alpha, IL-6 and NO. These findings demonstrate a crucial role of NM in the pathogenesis of Parkinson's disease by augmentation of microglial activation, leading to a vicious cycle of neuronal death, exposure of additional neuromelanin and chronification of inflammation. Antiinflammatory drugs may be one of the new approaches in the treatment of PD.

Involvement of benzodiazepine receptors in neuroinflammatory and neurodegenerative diseases: evidence from activated microglial cells in vitro

Increased binding of a ligand for the peripheral benzodiazepine binding receptor is currently used in PET studies as an in vivo measurement of inflammation in diseases like multiple sclerosis and Alzheimer's disease. Although peripheral-type benzodiazepin receptors (PBRs) are abundant in many cell types and expressed in the CNS physiologically only at low levels, previous reports suggest that after experimental lesions in animal models and in human neurodegenerative/-inflammatory diseases upregulated PBR expression with increased binding of its ligand PK11195 is confined mainly to activated microglia in vivo/in situ. Because the functional role of the PBR is unknown, we confirm by immunohistochemistry and PCR (I) that this receptor is expressed on microglia in vitro and (II) that benzodiazepines modulate proliferation of microglial cells and the release of the inflammatory molecules nitric oxide (NO) and tumor necrosis factor-alpha (TNF-alpha) in cell culture supernatants of primary rat microglia. Compared to lipopolysaccharide-activated controls the release of NO was markedly decreased in cultures treated with benzodiazepines (clonazepam, midazolam, diazepam) and the PBR ligand PK11195. Moreover, release of TNF-alpha and proliferation was significantly inhibited in the benzodiazepine-treated groups. These findings link the in vivo data of elevated PBR levels in neurodegenerative/-inflammatory diseases to a functional role and opens up possible therapeutic intervention targeting the PBR in microglia.

Intrathecal synthesis of monocyte chemoattractant protein-1 (MCP-1) in amyotrophic lateral sclerosis: further evidence for microglial activation in neurodegeneration

Autopsy studies and animal experiments suggest that microglial inflammation contributes to the pathogenesis of amyotrophic lateral sclerosis (ALS). Monocyte-chemoattractant protein (MCP-1) might play an important role in microglial recruitment. We studied MCP-1 levels in sera and cerebrospinal fluid of 29 ALS patients and compared the results with 11 control patients with tension headache. The MCP-1 level was determined using enzyme-linked immunosorbent assays (ELISA). A significant increase in cerebrospinal fluid MCP-1 level but not serum level was seen in the patients with ALS compared to the control subjects. These results suggest that cerebrospinal fluid MCP-1 activity may be a sensitive marker for neuroinflammation in ALS useful for monitoring treatment trials in ALS.

[MRI in the diagnosis of non-compacted ventricular myocardium (NCVM) compared to echocardiography]

PURPOSE

To report the detection of non-compacted ventricular myocardium (NCVM) with MRI compared to echocardiography in 8 patients.

MATERIAL AND METHODS

Non-compaction of the ventricular myocardium is a congenital disorder characterized by an altered structure of the myocardial wall resulting from an intrauterine arrest in endomyocardial embryogenesis. The morphological findings consist of a prominent meshwork of multiple myocardial trabeculations and deep intertrabecular recesses, communicating with the left ventricular cavity. 8 consecutive patients (mean age 7.3 years) with clinical and echocardiographic signs of NCVM were examined by MRI (1.5 T, Vision, Siemens) in short axis and 2- and 4-chamber views, using T (1)-weighted TSE and Cine-GRE in 6 patients and true FISP sequences in 2 patients. MRI and echocardiography were evaluated for visibility, signs of NCVM and involvement of myocardial wall segments. Thickness was measured for non-compacted and compacted myocardium and the non-compacted to compacted (N/C) ratio calculated.

RESULTS

MRI diagnosed 6 of 8 patients of having NCVM. Myocardial thickness as measured by echocardiography and MRI showed a good correlation in compacted myocardium (r = 8.82) and no correlation in non-compacted myocardium (r = 0.4). In 2 cases, non-compacted myocardium was detected but echocardiography did not reach the N/C ratio > 2 as required to diagnose NCVM in accordance with the criteria found in the literature. Both patients were also misdiagnosed by MRI performed with Cine-GRE. MRI reached a N/C ratio > 2 in only three patients. Newer TruFisp sequences showed no definite advantages. Extent of non-compaction could be visualized correctly with MRI.

CONCLUSION

Echocardiography is the method of choice to detect NCVM. MRI can be an alternative in some cases. The diagnosis of NCVM should not be considered until N/C ratio is over 2.

Stromal cell-derived factor 1 is secreted by meningeal cells and acts as chemotactic factor on neuronal stem cells of the cerebellar external granular layer

The cerebellar external granular layer (EGL) is an unusually long-lasting neural proliferative zone positioned immediately beneath the pial surface. Its position and stability critically depend on meningeal cells, as their selective destruction leads to its rapid dispersal, creating massive cortical ectopia. Similar ectopias have recently been described as a side effect of deficiency for stromal cell-derived factor 1 (SDF-1), a chemoattractant for haematopoietic precursor cell migration. Here we show that SDF-1 is present in meningeal cells in vivo and in vitro, where it is secreted in functionally relevant concentrations into the medium. Correspondingly, the SDF-1 receptor (termed CXCR4) can be demonstrated on stem cells of the external granular layer, but is absent on postmitotic cells commencing their final inward migration. We show that SDF-1 is concentrated by heparan sulphate proteoglycans highly expressed in the EGL in a laminar fashion, which thus might act to locally restrict SDF-1 action to the EGL in a kind of step gradient. In vitro, SDF-1 chemotactically attracts neuronal cells isolated from the external, but not from the internal granular layer, in a Boyden chamber assay in concentrations found in meningeal cell-conditioned medium. Selective removal of SDF-1 from conditioned media by immunoprecipitation abolishes their chemoattractive action, which can be reconstituted again by the addition of recombinant SDF-1. Meningeal cells are thus an important source for the expression of SDF-1 during brain development, which--comparable to its role in haematopoiesis--appears to be a key factor attracting precursor cells to their proliferative compartment.

Cerebrospinal fluid from patients with neurodegenerative and neuroinflammatory diseases: no evidence for rat glial activation in vitro

To determine the possible contribution of glial cells via oxidative stress/cytokine secretion in the pathogenesis of Parkinson's disease (PD), Alzheimer disease (AD), amyotrophic lateral sclerosis (ALS) or multiple sclerosis (MS) the concentration of nitric oxide (NO) (by the Griess method) and Interleukin-6 (IL-6) (by enzyme-linked immunosorbent assay) were measured in resting rat microglial and astrocytic cell culture supernatants stimulated by cerebrospinal fluid (CSF) (dilution 1:4, 1:10) from patients with the aforementioned diseases. Neither the concentration of NO (optical density at 450 nm: control, 0.036+/-0.006; MS, 0.034+/-0.008; AD, 0.031+/-0.006; PD, 0.02+/-0.01; lipopolysaccharide (LPS), 0.26+/-0.018) nor the amount of IL-6 (ng/ml: control, 0.112+/-0.026; PD, 0.12+/-0.027; MS, 0.123+/-0.008; ALS, 0.137+/-0.01; LPS, 1.81+/-0.11) differed in any disease group from those of unaffected controls. These findings suggest that the stimuli for inflammatory activation of glia are quite localized and not present in sufficient concentrations in the CSF of affected patients.

From theory to therapy: implications from an in vitro model of ramified microglia

Microglia are the principal immune cells in the central nervous system (CNS), characterized by a highly specific morphology and unusual antigenic phenotype. An increasing number of studies have focused on the role of microglia in the pathogenesis of neurodegenerative diseases. To elucidate the function of microglial cells under several neuropathological conditions, we have studied and established a cell culture model that allows us to cultivate microglial cells in their inactive, resting (ramified) phenotype. In the first part of this work, we describe the interaction of microglia cells with their epithelial (astrocytic) microenvironment. The second part reviews experiments with microglia cell cultures to elucidate underlying signalling pathways and summarizes recent advances of our knowledge in microglial molecular pathways that may ultimately lead to neurodegeneration.

ATP and adenosine induce ramification of microglia in vitro

Microglial cells in the healthy adult brain possess a characteristic ramified morphology with multiple branched processes, small somata and down-regulated inflammatory properties. In contrast, microglial cells isolated from new-born rat brain inevitably show a non-ramified amoeboid phenotype, which is observed in vivo after pathologic activation or during development. To identify factors that control microglial morphology we investigated the effects of purines alone or in combination with astrocyte-conditioned medium (ACM). Under optimized culture conditions postnatal rat microglial cells developed an amoeboid to ovoid phenotype. Addition of 0.6-1 mM ATP or adenosine induced the outgrowth of numerous processes after 2-3 days that could be observed also in the presence of ACM as previously reported. Culture in ACM plus ATP or adenosine yielded an optimized ramified phenotype. ATP or adenosine, but not ACM alone, also prevented the formation of a flat, amoeboid morphology induced by lipopolysaccharide (LPS); however, at 0.6-1 mM they did not reduce the initial LPS-induced activation of the transcription factor NF-kappaB. By using specific agonists or antagonists the morphological transformations could not be confined to a distinct purinoreceptor subtype, but appeared to be mediated by long-term presence of adenosine in the medium to which phosphorylated purines were rapidly hydrolyzed by microglial cells. Since ACM did not contain sufficient concentrations of ATP or adenosine, purines are not the only ramification-inducing factors present in ACM; however, they are a valuable tool to induce microglial ramification in vitro.

Analysis of the essential cell division gene ftsL of Bacillus subtilis by mutagenesis and heterologous complementation

The ftsL gene is required for the initiation of cell division in a broad range of bacteria. Bacillus subtilis ftsL encodes a 13-kDa protein with a membrane-spanning domain near its N terminus. The external C-terminal domain has features of an alpha-helical leucine zipper, which is likely to be involved in the heterodimerization with another division protein, DivIC. To determine what residues are important for FtsL function, we used both random and site-directed mutagenesis. Unexpectedly, all chemically induced mutations fell into two clear classes, those either weakening the ribosome-binding site or producing a stop codon. It appears that the random mutagenesis was efficient, so many missense mutations must have been generated but with no phenotypic effect. Substitutions affecting hydrophobic residues in the putative coiled-coil domain, introduced by site-directed mutagenesis, also gave no observable phenotype except for insertion of a helix-breaking proline residue, which destroyed FtsL function. ftsL homologues cloned from three diverse Bacillus species, Bacillus licheniformis, Bacillus badius, and Bacillus circulans, could complement an ftsL null mutation in B. subtilis, even though up to 66% of the amino acid residues of the predicted proteins were different from B. subtilis FtsL. However, the ftsL gene from Staphylococcus aureus (whose product has 73% of its amino acids different from those of the B. subtilis ftsL product) was not functional. We conclude that FtsL is a highly malleable protein that can accommodate a large number of sequence changes without loss of function.

The Bacillus subtilis cell division protein FtsL localizes to sites of septation and interacts with DivIC

FtsL is a small bitopic membrane protein required for vegetative cell division and sporulation in Bacillus subtilis. We investigated its localization by fluorescence microscopy using a green fluorescent protein (GFP) fusion. GFP-FtsL was localized at mid-cell in vegetative cells and at the asymmetric septum in sporulating cells. We also show that FtsL forms a ring-like structure at the division site and that it remains localized at mid-cell during the whole septation process. By yeast two-hybrid analysis and non-denaturing polyacrylamide gel electrophoresis (PAGE) with purified proteins, FtsL was found to interact with another membrane-bound division protein, the FtsL-like DivIC protein.

2-hydroxyglutaryl-CoA dehydratase from Clostridium symbiosum

Component D (HgdAB) of 2-hydroxyglutaryl-CoA dehydratase from Clostridium symbiosum was purified to homogeneity. It is able to use component A from Acidaminococcus fermentans (HgdC) to initiate catalysis together with ATP, Mg2+ and a strong reducing agent such as Ti(III)citrate. Component D from C. symbiosum has a 6 x higher specific activity compared with that from A. fermentans and contains a second [4Fe-4S] cluster but the same amount of riboflavin 5'-phosphate (1.0 per heterodimeric enzyme, m = 100 kDa). Mössbauer spectroscopy revealed symmetric cube-type structures of the two [4Fe-4S]2+ clusters. EPR spectroscopy showed the resistance of the clusters to reducing agents, but detected a sharp signal at g = 2. 004 probably due to a stabilized flavin semiquinone. Three genes from C. symbiosum coding for components D (hgdA and hgdB) and A (hgdC) were cloned and sequenced. Primer extension experiments indicated that the genes are transcribed in the order hgdCAB from an operon only half the size of that from A. fermentans. Sequence comparisons detected a close relationship to the dehydratase system from A. fermentans and HgdA from Fusobacterium nucleatum, as well as to putative proteins of unknown function from Archaeoglobus fulgidus. Lower, but significant, identities were found with putative enzymes from several methanogenic Archaea and Escherichia coli, as well as with the mechanistically related benzoyl-CoA reductases from the Proteobacteria Rhodopseudomonas palustris and Thauera aromatica.

Optic nerve regeneration after intravitreal peripheral nerve implants: trajectories of axons regrowing through the optic chiasm into the optic tracts

We have studied axon regeneration through the optic chiasm of adult rats 30 days after prechiasmatic intracranial optic nerve crush and serial intravitreal sciatic nerve grafting on day 0 and 14 post-lesion. The experiments comprised three groups of treated rats and three groups of controls. All treated animals received intravitreal grafts either into the left eye after both left sided (unilateral) and bilateral optic nerve transection, or into both eyes after bilateral optic nerve transection. Control eyes were all sham grafted on day 0 and 14 post-lesion, and the optic nerves either unlesioned, or crushed unilaterally or bilaterally. No regeneration through the chiasm was seen in any of the lesioned control optic nerves. In all experimental groups, large numbers of axons regenerated across the optic nerve lesions ipsilateral to the grafted eyes, traversed the short distal segment of the optic nerve and invaded the chiasm without deflection. Regeneration was correlated with the absence of the mesodermal components in the scar. In all cases, axon regrowth through the chiasm appeared to establish a major crossed and a minor uncrossed projection into both optic tracts, with some aberrant growth into the contralateral optic nerve. Axons preferentially regenerated within the degenerating trajectories from their own eye, through fragmented myelin and axonal debris, and reactive astrocytes, oligodendrocytes, microglia and macrophages. In bilaterally lesioned animals, no regeneration was detected in the optic nerve of the unimplanted eye. Although astrocytes became reactive and their processes proliferated, the architecture of their intrafascicular processes was little perturbed after optic nerve transection within either the distal optic nerve segment or the chiasm. The re-establishment of a comparatively normal pattern of passage through the chiasm by regenerating axons in the adult might therefore be organised by this relatively immutable scaffold of astrocyte processes. Binocular interactions between regenerating axons from both nerves (after bilateral optic nerve transection and intravitreal grafting), and between regenerating axons and the intact transchiasmatic projections from the unlesioned eye (after unilateral optic nerve lesions and after ipsilateral grafting) may not be important in establishing the divergent trajectories, since regenerating axons behave similarly in the presence and absence of an intact projection from the other eye.

Validation of risk adjustment models for in-hospital percutaneous transluminal coronary angioplasty mortality on an independent data set

OBJECTIVES

We sought to validate recently proposed risk adjustment models for in-hospital percutaneous transluminal coronary angioplasty (PTCA) mortality on an independent data set of high risk patients undergoing PTCA.

BACKGROUND

Risk adjustment models for PTCA mortality have recently been reported, but external validation on independent data sets and on high risk patient groups is lacking.

METHODS

Between July 1, 1994 and June 1, 1996, 1,476 consecutive procedures were performed on a high risk patient group characterized by a high incidence of cardiogenic shock (3.3%) and acute myocardial infarction (14.3%). Predictors of in-hospital mortality were identified using multivariate logistic regression analysis. Two external models of in-hospital mortality, one developed by the Northern New England Cardiovascular Disease Study Group (model NNE) and the other by the Cleveland Clinic (model CC), were compared using receiver operating characteristic (ROC) curve analysis.

RESULTS

In this patient group, an overall in-hospital mortality rate of 3.4% was observed. Multivariate regression analysis identified risk factors for death in the hospital that were similar to the risk factors identified by the two external models. When fitted to the data set, both external models had an area under the ROC curve >0.85, indicating overall excellent model discrimination, and both models were accurate in predicting mortality in different patient subgroups. There was a trend toward a greater ability to predict mortality for model NNE as compared with model CC, but the difference was not significant.

CONCLUSIONS

Predictive models for PTCA mortality yield comparable results when applied to patient groups other than the one on which the original model was developed. The accuracy of the two models tested in adjusting for the relatively high mortality rate observed in this patient group supports their application in quality assessment or quality improvement efforts.

In vitro-staining specificity of the antibody 5-D-4 for microglia but not for monocytes and macrophages indicates that microglia are a unique subgroup of the myelomonocytic lineage

We have previously shown that (i) the ramified phenotype and (ii) the microglia-specific pattern of membrane currents are induced not only in microglia, but also in monocytes and macrophages if they are cultured in the presence of astrocytes. These findings indicated that microglia are not a separate type of cell of the myelomonocytic lineage, but are induced to take on their unique characteristics by astrocytes. Recently, it was discovered that the antibody 5-D-4 selectively stains ramified microglia in situ. We therefore studied the influence of astrocytes and other epithelial cells on the expression of the keratan sulfate epitope recognized by 5-D-4 in microglia and other myelomonocytic cells. Our findings show that this antigen is exclusively expressed in microglia only if they are induced to ramify by coculture with either astrocytes or epithelial cells. By contrast monocytes and macrophages, even if induced to take on the ramified phenotype do not stain positive with 5-D-4. These findings indicate (i) that 5-D-4 is a specific marker for ramified microglia in vitro, and (ii) that microglia are a separate class of myelomonocytic cells, distinct from monocytes and macrophages.

Animal models of tremor

Animal models of tremor have been widely used in experimental neurology, because they are an indispensable requirement for understanding the pathophysiology of human tremor disorders and the development of new therapeutic agents. This review focuses on three approaches to produce tremor in animals (application of tremorgenic drugs, experimental central nervous system lesions, study of genetic mutants) and their use in simulating tremor syndromes of humans. Whereas harmaline induces a postural/kinetic tremor in animals that shares some features with human essential tremor/enhanced physiological tremor, MPTP tremor is the best model available for rest tremor in people. The tremor following experimental lesion of the ventromedial tegmentum in primates closely resembles Holmes tremor in humans, whereas cerebellar intention tremor is mimicked by cooling of the lateral cerebellar nuclei. The "campus syndrome," discovered in a breed of Pietrain pigs, might be a useful model of human orthostatic tremor. However, no animal model has yet been generated that exactly recreates all features of any of the known tremor disorders in humans. Problems encountered when comparing tremor in animals and humans include differing tremor frequencies and the uncertainty, if specific transmitter abnormalities/central nervous system lesions seen in animal tremor models are characteristic for their human counterparts. The search for adequate tremor models continues.

Validation in a community hospital setting of a clinical rule to predict preserved left ventricular ejection fraction in patients after myocardial infarction

BACKGROUND

A previous study showed that patients with previous myocardial infarction (MI) who meet 4 simple clinical and/or electrocardiographic criteria have a left ventricular ejection fraction (LVEF) of 40% or greater, with a positive predictive value of 98%. The objective of this study was to validate this clinical rule in the community hospital setting.

METHODS

Retrospective chart review in a 330-bed community hospital. Two hundred thirteen consecutive patients with MI were identified between June 1, 1993, and March 31, 1995. Left ventricular ejection fraction was predicted in a blinded fashion by means of the clinical rule before the actual LVEF test was reviewed.

RESULTS

We identified 213 patients admitted with the primary discharge diagnosis of acute MI. All patients met standard clinical and enzymatic definitions for acute MI and had at least 1 measure of LVEF, such as echocardiography, ventricular angiography, or gated blood pool scan. The clinical rule predicted that 83 patients (39.0%) would have an LVEF of 40% or greater. Of these 83 patients, 71 had an ejection fraction of 40% or greater, for a positive predictive value of 86%. Of the 12 patients who were incorrectly predicted to have a preserved LVEF, 6 (50%) had an index non-Q-wave anterior MI (P<.001). Reanalyzing the patient population with a fifth variable (anterior non-Q-wave MI) added to the original 4 variables increased the positive predictive value to 91%.

CONCLUSION

This simple clinical prediction rule has a positive predictive value of 86% when applied in the community hospital setting. Patients with anterior non-Q-wave MI may be 1 group in whom the rule is inaccurate, and expanding the clinical rule to 5 variables may increase the positive predictive value. When a technology-based assessment of left ventricular function is considered in patients after an MI, this prediction rule may allow for a more cost-effective patient selection, and as many as 40% of patients who have had acute MIs may require no testing at all.

The angiotensin II type 2 (AT2) receptor promotes axonal regeneration in the optic nerve of adult rats

The renin-angiotensin system (RAS) has been traditionally linked to blood pressure and volume regulation mediated through the angiotensin II (ANG II) type 1 (AT1) receptor. Here we report that ANG II via its ANG II type 2 (AT2) receptor promotes the axonal elongation of postnatal rat retinal explants (postnatal day 11) and dorsal root ganglia neurons in vitro, and, moreover, axonal regeneration of retinal ganglion cells after optic nerve crush in vivo. In retinal explants, ANG II (10(-7)-10(-5) M) induced neurite elongation via its AT2 receptor, since the effects were mimicked by the AT2 receptor agonist CGP 42112 (10(-5) M) and were entirely abolished by costimulation with the AT2 receptor antagonist PD 123177 (10(-5) M), but not by the AT1 receptor antagonist losartan (10(-5) M). To investigate whether ANG II is able to promote axonal regeneration in vivo, we performed optic nerve crush experiments in the adult rats. After ANG II treatment (0.6 nmol), an increased number of growth-associated protein (GAP)-43-positive fibers was detected and the regenerating fibers regularly crossed the lesion site (1.6 mm). Cotreatment with the AT2 receptor antagonist PD 123177 (6 nmol), but not with the AT1 receptor antagonist losartan (6 nmol), completely abolished the ANG II-induced axonal regeneration, providing for the first time direct evidence for receptor-specific neurotrophic action of ANG II in the central nervous system of adult mammals and revealing a hitherto unknown function of the RAS.

Meningeal cells stimulate and direct the migration of cerebellar external granule cells in vitro

The external granular layer is a secondary proliferative zone that arises from the caudolateral margin of the cerebellar ventricular zone and then spreads beneath the pial surface, eventually covering the entire cerebellar anlage. Here, both a part of the Bergmann glia and granule cells are generated. Selective destruction of the leptomeningeal cell layer during development in vivo disrupts the subpial extension of the external granular layer and the laminar deposition of its descendant cells. The mechanisms by which meningeal fibroblasts exert their controlling influence on cortical development have remained unclear but could involve diffusible factors and/or interactions mediated by direct cellular contacts. In order to test these assumptions, we have co-cultivated cerebellar slice explants with meningeal cells with and without interposition of a microfilter barrier. In this setup, meningeal cells by a diffusible factor stimulated the emigration of immature neurons exclusively from the external granular layer. This effect could also be elicited by fibroblasts from other tissues but not by nonfibroblastic cells such as, e.g., astroglia. In the Boyden chamber assay, the migration of undifferentiated neurons isolated from the external granular layer was chemotactically oriented towards the source of meningeal cell conditioned media. In comparison, neurons from the internal granular layer did not respond to this stimulus. The attraction of immature neurons towards the pial surface could (1) represent a mechanism for the establishment of (subpial) secondary proliferative zones and (2) hypothetically also play a role in the outward-directed migration of postmitotic cells, e.g., in the isocortical anlage.

Meningeal cells stimulate neuronal migration and the formation of radial glial fascicles from the cerebellar external granular layer

The cerebellar granule cell layer and partly the Bergmann glial scaffold arise from a secondary subpial proliferative zone, the external granular layer. Their development can be disrupted by selective destruction of meningeal cells. In order to clarify the mechanisms of meningeal control of cortical development, we have investigated the development of early postnatal rat cerebellar slice explants in different coculture set-ups with meningeal cells and other fibroblasts. Fibroblasts of various sources (1) stimulate migration of undifferentiated neurons from the explants by a diffusible factor and (2) trigger the development of a radial phenotype in glial cells by contact-mediated mechanisms involving basal lamina constituents. These data provide further evidence for the involvement of mesenchymal-epithelial interactions in the development of the cerebellar cortex.

Riboflavin-mediated axonal degeneration of postnatal retinal ganglion cells in vitro is related to the formation of free radicals

It is well known that glial cells produce several neurotrophic factors. We detected a neurogedegenerative/neurite growth inhibiting activity in serum-free astrocyte-conditioned medium (ACM). After high performance liquid chromatography (HPLC)-purification, spectral analysis and test of biologic activity in tissue cultures of postnatal retinal explants we isolated a fraction containing a riboflavin-(vitamin B2)-like compound which caused the neuronal degeneration. We therefore investigated the influence of pure riboflavin on axonal regeneration in vitro. Riboflavin is a normal compound of Dulbecco's modified Eagle medium (DMEM) and other tissue culture media in various concentrations. The removal of riboflavin from ACM by reversed phase chromatography abolished the neurite growth inhibiting effect and enhanced the regenerative response of axonal outgrowth from postnatal rat retinal explants. However, doubling of the normal medium concentration (1 microM) of riboflavin lead to strong degenerative alteration of the outgrowing axons in a dose-dependent manner, even under maximal growth stimulation by cultivating the explants in astrocyte-conditioned medium. To check the possibility that riboflavin-mediated cytotoxicity is related to the production of free radicals through photoabsorption from daylight, we irradiated culture medium with UV light, and induced radical stress by incubating the explants with Fe2+/3+. In an other set of experiments, we proofed, if antioxidants/free radical scavengers like pyruvate or vitamin C and E are able to overcome the neurite growth inhibiting influence of riboflavin or the radical stress. Our findings suggest an involvement of riboflavin-mediated formation of free radicals/reactive oxygen species and subsequent neurite degeneration in in vitro-assays of neuronal regeneration or neuronal cell cultures. How far the riboflavin/free radical-induced axonal degeneration could be an explanation for neurological degenerative disorders has to be elucidated.

Surgical delay for acute type A dissection with malperfusion

BACKGROUND

An acute type A aortic dissection is considered a surgical emergency. Review of the risk factors for a type A dissection showed that preoperative malperfusion was associated with a 22% (2/9) intraoperative mortality and an 89% (8/9) hospital mortality. Intraoperative deaths were secondary to pulmonary failure resulting from capillary leak; the remaining patients died of multiorgan failure resulting from reperfusion injury.

METHODS

The surgical delay approach was adopted for malperfused patients, and treatment in these patients included percutaneous reperfusion, with aortic fenestration and branch stenting where appropriate. Twenty patients had a type A dissection and malperfusion shown by pulsed-wave Doppler echocardiography, transesophageal echocardiography, or spiral computed tomographic scanning. Malperfusion was documented by angiography. After reperfusion, all patients' conditions were stabilized in the intensive care unit; intravenous beta-blockers were administered to decrease the maximum rate of increase of left ventricular pressure. Once patients completely recovered from the consequences of malperfusion, surgical repair was performed. Statistical comparison of the non-delay and delay groups was performed using Fisher's exact test and Student's t test. Multiple logistic regression analysis was used to establish independent predictors for mortality.

RESULTS

The mean delay to repair was 20 days (2 to 67 days). Four (31%) patients were discharged home and readmitted for operation. Three patients (15%) died preoperatively, 1 of retrograde dissection and rupture and 2 of reperfusion injury. Seventeen underwent surgical repair, with two deaths (12%); 15 (75%) were discharged, with an average follow-up of 16.8 months (p < 0.003). Delay was the only independent predictor of outcome.

CONCLUSIONS

Patients with an acute type A dissection and malperfusion should undergo percutaneous reperfusion, and surgical repair should be delayed until the reperfusion injury resolves.

YVAD protect post-natal retinal ganglion cells against axotomy-induced but not free radical-induced axonal degeneration in vitro

In the developing central nervous system (CNS), the differentiation of neurons is accompanied by a large amount of cell loss in the form of programmed cell death (apoptosis). On the other hand, injury in the adult CNS often results in permanent neuronal degeneration leading to the failure of axonal regeneration. This could be related to an axotomy-induced activation of an apoptotic program. The interleukin-1beta-converting enzyme family of proteases has been implicated in playing a fundamental role in apoptotic processes in both invertebrates and vertebrates. In order to determine what role, if any, inhibitors of the interleukin-1beta-converting enzyme family might play in axonal regeneration after axotomy we employed an in vitro system using retinal explants from post-natal rats at the age between 9 and 12 days [R. Lucius, P. Young, S. Tidow and J. Sievers, Growth stimulation and chemotropic attraction of retinal ganglion cell axons in vitro by co-cultured optic nerves, astrocytes and astrocyte conditioned medium, Int. J. Dev. Neurosci., Vol. 14 (1996) 387-398]. The retinal ganglion cells in this model are comparable to adult animals in their regenerative response (D. Alcutt, M. Berry and J. Sievers, A qualitative comparison of the reaction of retinal ganglion cells to optic nerve crush in neonatal and adult mice, Dev. Brain Res., Vol. 16 (1984a) 231-240; D. Allcutt, M. Berry and J. Sievers, A quantitative comparison of the reaction of retinal ganglion cells to optic nerve crush in neonatal and adult mice, Dev. Brain Res., Vol. 16 (1984b) 219-230]. The addition of the synthetic peptide inhibitor YVAD (Ac-Tyr-Val-Ala-Asp-aldehyde), which reversible inhibits interleukin-1beta-converting enzyme and subsequent apoptosis, enhances the number and length of regenerating neurites of retinal ganglion cells. However, this manipulation was not able to overcome free radical-induced axonal degeneration/neuronal apoptosis, suggesting at least two different death pathways leading to neuronal degeneration/cell death. These results provide the first evidence that inhibitors of key enzymes of the apoptotic program could play a beneficial role to overcome neurite degeneration after axotomy in the adult mammalian CNS.

Ramification of microglia, monocytes and macrophages in vitro: influences of various epithelial and mesenchymal cells and their conditioned media

Microglial cells are able to switch between an "active" amoeboid and a ramified "resting" morphology during development and after experiencing lesions. We have previously shown that in vitro microglial morphology is controlled by their cellular environment, i. e. cells become ramified in astrocyte coculture but amoeboid on monolayers of fibroblasts. In the present study we have extended the analysis of the control of macrophage morphology by maintaining macrophages of different origins in coculture with different epithelial or mesenchymal cells and their conditioned media. Microglia, monocytes and spleen macrophages seeded onto monolayers of astrocytes, kidney epithelia or hepatoma cells developed the ramified morphology but remained amoeboid in fibroblast coculture. Ramification was also induced by media conditioned by these cells as well as by phorbolic esters, i.e. activators of protein kinase C. In double coculture assays, even small numbers of fibroblasts were able to override the "epithelial" influence. Likewise, microglia remained amoeboid, when incubated on several constituents of the extracellular matrix. These results indicate that macrophage ramification is an active process initiated by diffusible factors secreted by various epithelial cells, possibly acting upon a protein-kinase-C-related receptor. We interprete the modification of macrophage morphology as a functional adaptation to the surrounding type of tissue that is enforced by its constituent cells. Thus, the specific morphologies of microglia, hepatic von Kupffer's cells or peritubular kidney macrophages could be explained by similar epithelium-macrophage interaction.

Postnatal retinal ganglion cells in vitro: protection against reactive oxygen species (ROS)-induced axonal degeneration by cocultured astrocytes

Reactive oxygen species (ROS) are supposed to be involved in neurodegenerative processes like Parkinson's or Alzheimer's disease. Beside this there are an increasing number of studies indicating an involvement of ROS in traumatic brain injury. We therefore studied the potential role of astrocytes against neurotoxic effects of ROS in cocultures of rat cortical astrocytes with regenerating postnatal retinal ganglion cells (RGC). The sydnonimine SIN-1, which spontaneously decomposes to yield nitric oxide (NO) and superoxide anion radicals, led to axonal degeneration at concentrations between 1 microM and 10 microM. Comparable effects were seen after addition of iron salts (Fe2+/Fe3+), which catalyze the generation of hydroxyl radicals. In contrast, in cocultures of RGC with astrocytes or after addition of free radical scavengers there was no neurotoxic/neurodegenerative effect of ROS as compared with control cultures. Vitamin E (1-10 microM) and vitamin C (10-100 microM) abolished the neurotoxic effect of both SIN-1 or iron ions. Beside this, there was an additional effect concerning the number and the length of neurites growing out from the retinal explant: in cocultures both parameters were greatly enhanced. These results suggest that (i) astrocytes are able to protect retinal ganglion cells against ROS-induced oxidative stress, (ii) astrocytes release soluble neurotrophic factors supporting RGC axonal regeneration, and (iii) free radical production after tissue injury may partly contribute to the failure of axonal regeneration in the adult mammalian central nervous system.

Growth stimulation and chemotropic attraction of rat retinal ganglion cell axons in vitro by co-cultured optic nerves, astrocytes and astrocyte conditioned medium

The effects of explants of optic nerves of different ontogenetic ages (P0 P14, adult), and of cultured astrocytes of various ages on the neurite regeneration of rat retinal ganglion cells (RGC) were assessed in vitro, using a three-dimensional culture system which allows the co-cultivation of various explants. Both co-cultured P0-P12 optic nerves and astrocyte cultures from P2 cerebral cortex stimulated the regeneration of neurites from the retinal explants after 3 days in culture. By contrast, P14 and older explants of the optic nerve, astrocytes from P17 optic nerve and astrocytes that had previously been grown in culture for more than 6 weeks had no effect on RGC neurite outgrowth. Moreover, both the P0-P12 optic nerve explants and the astrocytes from P2 cerebral cortex also seemed to have a chemotropic effect on the regenerating neurites, because the latter were longer on the side facing the co-explantat. The absence of a cellular bridge between retinal and optic nerve explants suggests that the effects are mediated by astroglia-derived diffusible neurite growth promoting factors. Accordingly, astrocyte-conditioned medium from P2 astrocytes also stimulated the outgrowth of neurites from the retinal explants. These findings show that immature astrocytes of a limited ontogenetic period release as yet unknown diffusible neurite growth-promoting factors which stimulate the regeneration of neurites from retinal explants.

Regeneration in the optic nerve of adult rats: influences of cultured astrocytes and optic nerve grafts of different ontogenetic stages

We have studied the effects of transplanted optic nerves of different ontogenetic stages (E19 to adult), and cultured astrocytes from P2 cerebral cortex on the regeneration of axons in the optic nerve of adult rats. Regeneration was visualized by anterograde tracing with rhodamine-iso-thiocyanate. Grafts were identified with Nuclear Yellow. Astroglia within both the cut optic nerve and the transplants were detected by anti-glial fibrillary acidic protein staining. In control animals (cut optic nerve, 2-3 mm behind the optic disc), only a few neurites were found 15 days after the operation which grew randomly for short distances into the surrounding meningeal sheaths. Perinatal (E19 to P2) optic nerves induced a massive outgrowth of RITC-filled axons from the host optic nerve. The regenerating fibres grew for up to 3 mm towards the graft, ahead of glial fibrillary acidic protein-positive astroglia emanating from the host optic nerve that seemed to follow them. Although the regenerating fibres reached the grafts, they did not penetrate them. Optic nerve grafts of increasing age elicited smaller growth responses; e.g. grafts from P8 promoted only a very limited (several 100 microns) growth response, grafts from P12 and later induced outgrowth comparable with that of control animals. Grafted astrocytes from P2 donors that had previously been grown in culture, were also capable of promoting outgrowth of rhodamine-iso-thiocyanate-filled axons from the host optic nerve. These findings suggest that only astrocytes at an immature stage of differentiation are capable of inducing axon growth from the adult optic nerve. Furthermore, the absence of an obvious cellular bridge between host and graft suggests that the graft effect is probably mediated by the release of astroglia-derived diffusible neurite growth promoting factors.

Enkephalin metabolism by microglial aminopeptidase N (CD13)

Rat microglia in culture showed a high capacity to degrade neuropeptides compared with other glial cells. Leu-enkephalin was readily hydrolyzed to free tyrosine and Gly-Gly-Phe-Leu. Inhibition experiments and immunostaining revealed that aminopeptidase N (CD13) on the surface of microglia was responsible for enkephalin cleavage. Endopeptidase-24.11 ("enkephalinase"), angiotensin-converting enzyme, or carboxypeptidases could not be detected on microglia. Aminopeptidase N activity in microglia was considerably higher than in rat peripheral monocytes and macrophages, which both also exhibited low endopeptidase 24.11 activities. Activity of aminopeptidase N was upregulated by culture of microglia on astrocytes and down-regulated by exposure of microglia to lipopolysaccharide. The occurrence of aminopeptidase N on microglia is in line with the view that they originate from the monocytic lineage.

Blood monocytes and spleen macrophages differentiate into microglia-like cells on monolayers of astrocytes: morphology

Several morphological and functional properties of microglial cells, the resident immunoeffector cells of the central nervous system (CNS), differ from those of monocytes/macrophages in other tissues. Microglia are assumed to derive from myelonocytic lineage, possibly as a distinct subpopulation that diverges from a common cell line early in ontogeny, invades the CNS, proliferates, and differentiates into ameboid and then ramified microglia. We tested the hypothesis that some morphological and functional properties of microglia are induced in myelomonocytic cells by nervous tissue, specifically astrocytes. In the present in vitro studies we compared the differentiation of microglia, blood monocytes, and spleen macrophages on acellular substrates and on monolayers of astrocytes and fibroblasts. On acellular substrates, microglial cells at first acquire an ameboid morphology; later they show a few short, unbranched processes. On monolayers of pure astrocytes, microglial cells at first also differentiate into ameboid cells, but after 5 to 7 days they start to develop processes with large lamellopodial tips. These lengthen and branch continuously during the next 2 weeks in vitro, demarcating a round to oval territory around the small ellipsoid cell body. By contrast, on monolayers of fibroblasts the microglial cells develop an ameboid morphology, but do not grow the typical long branched processes of the ramified form. Blood monocytes and spleen macrophages behave indistinguishably from microglia both on acellular and cellular substrates, i.e., on astroglia they develop the ramified form, while on fibroblasts they retain the ameboid shape. When microglia, macrophages, or monocytes are cultured on coverslips on top of astrocytic monolayers, i.e., physically separated from the astroglia, but exposed to the medium conditioned by astrocytes, a significant proportion of them also develop the ramified shape. These findings indicate that the ramified shape of microglia is induced by astrocytes. Since this morphology can also be induced in blood monocytes and macrophages, we take this to be further evidence for the proposition that microglial cells are derived from the myelomonocytic lineage, and, moreover, that properties of resident macrophages are largely determined by tissue components of their host organ.

Blood monocytes and spleen macrophages differentiate into microglia-like cells on monolayers of astrocytes: membrane currents

Microglia, the resident macrophages of the central nervous system (CNS), can be distinguished from most other cells of the myelomonocytic lineage by a distinct pattern of membrane currents. In the accompanying paper we have shown that the characteristic morphological feature of microglia, ramification, develops both in microglia and other myelomonocytic cells when they are cocultured with astrocytes. We therefore propose that the electrophysiological properties of microglia also develop under the influence of astrocytes, and, moreover, that these properties can also be induced in other cells of the myelomonocytic lineage. Microglia cultured on poly-d-lysine or on a monolayer of fibroblasts possess an inwardly rectifying K(+)-current only, which is of composite nature. In single-channel recordings two types of K(+)-channels are found: i) a noninactivating channel with a conductance of 43pS, and ii) an inactivating channel with 32pS. Microglia cultured on a monolayer of astrocytes additionally develop an outward K(+)-current and a Na(+)-current. The electric parameters of activation and inactivation of the microglial Na(+)-current are identical to those of the neuronal Na(+)-current. Monocytes from peripheral blood and macrophages from spleen exhibit no inward currents. However, when these cells are cocultured with astrocytes they develop microglia-like membrane currents, including the inward and outward K(+)-rectifyer and the Na(+)-current. By contrast, on fibroblasts they retain their macrophage current profile. The expression of the microglia-like membrane currents in the mononuclear phagocytes is induced by a diffusible factor released from the astrocytes into the culture medium, since monocytes and microglia develop the mature microglial current profile, when cultured in astrocyte conditioned medium.(ABSTRACT TRUNCATED AT 250 WORDS)

Signal transduction pathway of the muscarinic receptors mediating gallbladder contraction

In gallbladder smooth muscle, carbachol interacts with M3 receptors to mediate contraction. To examine components of the intracellular second messenger system that is coupled to these receptors we have tested whether carbachol stimulates the formation of inositol phosphates (IP) to cause contraction. Guinea pig gallbladder muscle strips were prelabeled with [3H]inositol and were incubated with 0.1 mmol/l carbachol, a concentration causing maximal contraction. [3H]inositol monophosphates, [3H]inositol bisphosphates and [3H]inositol trisphosphates and contraction were measured at various times (0-90 s). To examine whether a pertussis toxin-sensitive guanine nucleotide binding protein is coupled to the muscarinic receptors, guinea pigs were pretreated with pertussis toxin (180 micrograms/kg i.v./24 h). The effectiveness of pertussis toxin treatment was determined by measuring [32P]ADP-ribosylation of a approximately 40/41 kDa protein from gallbladder homogenates. Carbachol caused a significant time-dependent increase in the formation of [3H]inositol monophosphates, [3H]inositol bisphosphates and [3H]inositol trisphosphates. The time course of [3H]inositol trisphosphate turnover caused by carbachol was biphasic, and was detectable at 15 s and maximal at 60 s; at 75 s and 90 s formation of [3H]inositol trisphosphates decreased, whereas the time course of carbachol-induced contraction of the gallbladder smooth muscle strips reached a plateau after 90 s. The effects of carbachol on [3H]inositol trisphosphates and on contraction were abolished by atropine.(ABSTRACT TRUNCATED AT 250 WORDS)

Regeneration of axons into the trochlear rootlet after anterior medullary lesions in the rat is specific for ipsilateral IVth nerve motoneurones

The fibre projection from the IVth nerve nucleus to the superior oblique muscle was determined quantitatively in the normal rat by defining fibre numbers in transverse sections of the IVth nerve, and neurone numbers after retrograde labelling by horseradish peroxidase (HRP) injection into the muscle. There were 183 +/- 27 (S.E.) labelled neurones in the nucleus contralateral to the injected muscle and only 2 +/- 1 ipsilateral. The ipsilateral fibre number was 234 +/- 7 and the cell/axon ratio 0.8 +/- 0.1. Extensive analysis of all HRP retrogradely labelled material revealed no central fibre contribution to the IVth nerve other than from neurones resident in the trochlear nucleus. The central portion of the trochlear nerve tract was severed at its point of decussation in the anterior medullary velum. Ninety days after lesion, 10 +/- 4 (6% of control) neurones were labelled in the ipsilateral trochlear nucleus; none were labelled in the contralateral nucleus or in any other part of the midbrain, pons, medulla, or cerebellum. The number of myelinated fibres in the IVth nerve had decreased to 21 +/- 5 (9% of control) so that the cell/axon ratio was 0.4 +/- 0.2, thus suggesting that a single motoneurone has more fibres after lesion. In electron micrographs of the IVth nerve, larger than normal numbers of unmyelinated fibres were seen. Many myelinated fibres displayed signs of abnormal myelination. After regeneration, the projection was exclusively ipsilateral and not crossed as in the normal. These findings establish that there is a high degree of specificity after regeneration since no myelinated central nervous system axons other than trochlear fibres select the IVth nerve root as a trajectory over which to regenerate.