Characterization of intrinsically disordered regions in proteins informed by human genetic diversity.

All proteomes contain both proteins and polypeptide segments that don't form a defined three-dimensional structure yet are biologically active-called intrinsically disordered proteins and regions (IDPs and IDRs). Most of these IDPs/IDRs lack useful functional annotation limiting our understanding of their importance for organism fitness. Here we characterized IDRs using protein sequence annotations of functional sites and regions available in the UniProt knowledgebase ("UniProt features": active site, ligand-binding pocket, regions mediating protein-protein interactions, etc.). By measuring the statistical enrichment of twenty-five UniProt features in 981 IDRs of 561 human proteins, we identified eight features that are commonly located in IDRs. We then collected the genetic variant data from the general population and patient-based databases and evaluated the prevalence of population and pathogenic variations in IDPs/IDRs. We observed that some IDRs tolerate 2 to 12-times more single amino acid-substituting missense mutations than synonymous changes in the general population. However, we also found that 37% of all germline pathogenic mutations are located in disordered regions of 96 proteins. Based on the observed-to-expected frequency of mutations, we categorized 34 IDRs in 20 proteins (DDX3X, KIT, RB1, etc.) as intolerant to mutation. Finally, using statistical analysis and a machine learning approach, we demonstrate that mutation-intolerant IDRs carry a distinct signature of functional features. Our study presents a novel approach to assign functional importance to IDRs by leveraging the wealth of available genetic data, which will aid in a deeper understating of the role of IDRs in biological processes and disease mechanisms.

Comprehensive characterization of amino acid positions in protein structures reveals molecular effect of missense variants.

Interpretation of the colossal number of genetic variants identified from sequencing applications is one of the major bottlenecks in clinical genetics, with the inference of the effect of amino acid-substituting missense variations on protein structure and function being especially challenging. Here we characterize the three-dimensional (3D) amino acid positions affected in pathogenic and population variants from 1,330 disease-associated genes using over 14,000 experimentally solved human protein structures. By measuring the statistical burden of variations (i.e., point mutations) from all genes on 40 3D protein features, accounting for the structural, chemical, and functional context of the variations' positions, we identify features that are generally associated with pathogenic and population missense variants. We then perform the same amino acid-level analysis individually for 24 protein functional classes, which reveals unique characteristics of the positions of the altered amino acids: We observe up to 46% divergence of the class-specific features from the general characteristics obtained by the analysis on all genes, which is consistent with the structural diversity of essential regions across different protein classes. We demonstrate that the function-specific 3D features of the variants match the readouts of mutagenesis experiments for BRCA1 and PTEN, and positively correlate with an independent set of clinically interpreted pathogenic and benign missense variants. Finally, we make our results available through a web server to foster accessibility and downstream research. Our findings represent a crucial step toward translational genetics, from highlighting the impact of mutations on protein structure to rationalizing the variants' pathogenicity in terms of the perturbed molecular mechanisms.

MISCAST: MIssense variant to protein StruCture Analysis web SuiTe.

Human genome sequencing efforts have greatly expanded, and a plethora of missense variants identified both in patients and in the general population is now publicly accessible. Interpretation of the molecular-level effect of missense variants, however, remains challenging and requires a particular investigation of amino acid substitutions in the context of protein structure and function. Answers to questions like 'Is a variant perturbing a site involved in key macromolecular interactions and/or cellular signaling?', or 'Is a variant changing an amino acid located at the protein core or part of a cluster of known pathogenic mutations in 3D?' are crucial. Motivated by these needs, we developed MISCAST (missense variant to protein structure analysis web suite; http://miscast.broadinstitute.org/). MISCAST is an interactive and user-friendly web server to visualize and analyze missense variants in protein sequence and structure space. Additionally, a comprehensive set of protein structural and functional features have been aggregated in MISCAST from multiple databases, and displayed on structures alongside the variants to provide users with the biological context of the variant location in an integrated platform. We further made the annotated data and protein structures readily downloadable from MISCAST to foster advanced offline analysis of missense variants by a wide biological community.

Effect of obesity on sinonasal disease in asthma.

OBJECTIVE: Sinonasal disease can contribute to poor asthma control. There are reports that link obesity with an increased prevalence of sinonasal disease, but no studies evaluating the severity of sinonasal disease in obese asthmatics, and how this impacts asthma control. The purpose of the current study was to determine if obesity is associated with increased severity of sinonasal disease, and/or affects response to nasal corticosteroid treatment in asthma. METHODS: This study included 236 adults participating in a 24-week randomized, double-masked, placebo-controlled study of nasal mometasone for the treatment of poorly controlled asthma. Sinonasal disease severity was assessed using validated questionnaires, and compared in participants of differing BMIs. Eosinophilic inflammation was assessed using markers in nasal lavage, serum and exhaled nitric oxide. Response to treatment was compared in different BMI groups. RESULTS: Obesity had no effect on the severity of sinonasal disease symptoms in asthmatics (Sino-Nasal Outcome Test 22 (SNOT 22) score [mean ± SD] 35.4 ± 18.5, 40.2 ± 22.8, and 39.1 ± 21.7, p = 0.43, in lean, overweight and obese participants), nor on nasal, bronchial or systemic markers of allergic inflammation. Nasal steroids had some limited effects on symptoms, lung function and inflammatory markers in lean participants, but no detectable effect was found in obese patients. CONCLUSIONS: Obesity does not affect severity of sinonasal disease in patients with asthma; the association of sinonasal disease symptoms with increased asthma severity and markers of Type 2 inflammation are consistent across all BMI groups. The response of obese patients to nasal corticosteroids requires further study.

Urinary Bladder Carcinosarcoma (Sarcomatoid Carcinoma) With Long Survival After Transurethral Resection: A Case Report.

Carcinosarcoma or sarcomatoid carcinoma of the urinary bladder is a rare but aggressive bladder cancer characterized by malignant epithelial and mesenchymal components, with only a few cases reported in the literature so far. In this report, we discuss a case of a 74-year-old female nonsmoker who presented with intermittent hematuria and passage of clots in the last four months. Radiographic images showed an irregular mass lesion (6.2 x 6 cm) in the left lateral wall of the urinary bladder near to left vesicoureteral junction. The mass was completely removed with transurethral resection of the bladder tumor (TUR-BT). Histopathological study revealed high-grade carcinosarcoma, and immunohistochemistry showed diffuse positivity for vimentin, pan-cytokeratin (CK) and CK7, epithelial membrane antigen (EMA), and CK5/6. The patient declined radical cystectomy and only agreed to receive intravesical chemotherapy (gemcitabine), and she remains alive after more than four years of follow-up. Carcinosarcoma of the urinary bladder is a rare tumor primarily affecting older people, and it is most commonly treated with radical cystectomy and different combination treatments such as chemotherapy and radiation. However, tumor resection followed by intravesical chemotherapy may be an alternative option in the early stages of bladder carcinosarcoma for some patients, thereby avoiding the need for aggressive treatments, especially for elderly patients who decline to undergo radical surgery.

In vivo tissue reaction within the outflow conduit in patients supported by HeartWare HVAD.

AIM: The frequency, extent, and nature of tissue ingrowth within the continuous-flow left ventricular assist device (cf-LVAD) outflow conduit has not been systematically assessed. We sought to characterize conduit histopathology at explantation in a cohort of patients with HeartWare ventricular assist device (HVAD) and assess the effect on pump performance. METHODS: Patients undergoing routine histopathological assessment of a HeartWare HVAD removed at transplantation or autopsy were assessed. Outflow conduits were examined macroscopically, and visible tissue was sectioned for microscopic evaluation. In patients who had undergone prior contrast-enhanced computerized tomography (CT) with HVAD in situ, the outflow conduit was measured at the aortic anastomosis and 5 cm proximal to the anastomosis, in the axial and sagittal planes. All patients had their pump flow, flow pulsatility, current, and speed determined from log files examined at 1, 3, 6, 9, and 12 months after LVAD implantation. RESULTS: Twenty-five consecutive patients were assessed (24 LVAD, 1 biventricular assist device (BiVAD)). Of the 26 outflow grafts assessed, there was evidence of tissue ingrowth reaction in 24 (92%) grafts. The most common site was the distal anastomosis (18/24, 75%), with the graft body involved in 14 of 24 (58%) grafts. Microscopic evaluation revealed acute inflammatory infiltrate in 4 of 24 grafts (17%), chronic inflammatory infiltrate in 14 of 24 (58%), neointima formation in 18 of 24 (75%) and fibrosis in 18 of 24 (75%) grafts. The median depth of tissue was 1 mm (range, 0-2 mm). The mean conduit diameter was 9.5 ± 0.6 mm at the aortic anastomosis compared with 11.1 ± 0.5 mm 5 cm proximal to the anastomosis (p < 0.0001). In patients with unchanged pump speed one month after implantation, analysis of log files revealed a significant (5.8 ± 8.6%) decrease in pump flow (4.65 ± 0.86 vs 4.38 ± 0.92 L/min, p = 0.01) and flow pulsatility (5.00 ± 1.10 vs 4.16 ± 1.05 L/min, p = 0.006). CONCLUSIONS: There is evidence of tissue formation within the HVAD outflow conduit in the vast majority of patients, most commonly located at the aortic anastomosis. This is associated with significantly decreased pump flow over time.

The dorsal midbrain anticonvulsant zone--II. Efferent connections revealed by the anterograde transport of wheatgerm agglutinin-horseradish peroxidase from injections centred on the intercollicular area in the rat.

Activation of the dorsal midbrain has a powerful anticonvulsant effect in the maximal electroshock model of epilepsy. The suppression of tonic seizures can be obtained most reliably from an area centred on the intercollicular nucleus overlapping into the deep layers of the superior colliculus and adjacent mesencephalic reticular formation. As part of a series of investigations to identify neural mechanisms responsible for mediating the anticonvulsant properties of the dorsal midbrain, the present study provides an anatomical description of the efferent projections of this region. Small amounts of wheatgerm agglutinin-horseradish peroxidase (10-30 nl of a 1% solution) were injected into the intercollicular nucleus and surrounding tissue. The resulting anterograde transport of the tracer was plotted on a set of standard atlas sections. Four major output pathways were identified: (i) an ipsilateral descending projection which had terminations in the microcellular tegmental nucleus, lateral and ventral pontine reticular nucleus pars oralis, ventrolateral tegmental nucleus, ventral and caudal pontine reticular nucleus pars caudalis, raphe magnus nucleus and the gigantocellular nucleus; (ii) a contralateral descending projection which for the most part targeted the same brainstem structures but with weaker terminal labelling; (iii) a projection to the contralateral dorsal midbrain with comparatively weak terminal label in the contralateral superior colliculus, intercollicular nucleus, periaqueductal gray, mesencephalic reticular formation and cuneiform area; (iv) ipsilateral ascending pathway with terminations in the red nucleus, zona incerta, peripeduncular area, parafascicular nucleus, lateral hypothalamus, parts of the pretectum and caudal thalamus. At a general level the dorsal midbrain anticonvulsant zone shares its major output projections and efferent targets with at least one of its near neighbours, including the superior colliculus, periaqueductal gray, the cuneiform nucleus and pedunculopontine nucleus. The possibility that anticonvulsant properties of the intercollicular area can simply be attributed to a unique set of efferent projections is therefore not supported by the anatomy.

The dorsal midbrain anticonvulsant zone--I. Effects of locally administered excitatory amino acids or bicuculline on maximal electroshock seizures.

Microinjections of bicuculline methiodide into the dorsal midbrain anticonvulsant zone, a region which includes the caudal deep layers of the superior colliculus, the adjacent mesencephalic reticular formation and the intercollicular nucleus, suppress tonic hindlimb extension induced by maximal electroshock. The purpose of the present experiments was to establish the most effective and convenient method for eliciting anticonvulsant properties from the dorsal midbrain using the electroshock model of epilepsy. A comparison of different injections of excitatory amino acids and bicuculline into the dorsal midbrain of the rat showed: (i) injections of kainate suppressed hindlimb extension but only at substantially larger doses (i.e. 200-400 pmol) than 50 pmol of bicuculline, which produced generally superior effects; (ii) quisqualate provided only weak protection against tonic seizures at doses that produced neurotoxic effects (2-40 nmol); (iii) N-methyl-D-aspartate was ineffective at doses which produced mild clonic seizure in their own right (2-4 nmol) and also produced some evidence of neurotoxicity; (iv) the suppression of hindlimb extension by bicuculline was dose related, and the lowest bilateral dose for producing reliable suppression was 50 pmol/400 nl per side; and (v) a unilateral injection of 100 pmol/400 nl also reliably suppressed hindlimb extension. The latter finding had important implications for the design and interpretation of the following lesion study. Injections of bicuculline into the dorsal midbrain also produced defence-like behavioural responses that included running and biting; the intensity of these responses correlated with the suppression of hindlimb extension.(ABSTRACT TRUNCATED AT 250 WORDS)

The dorsal midbrain anticonvulsant zone--III. Effects of efferent pathway transections on suppression of electroshock seizures and defence-like reactions produced by local injections of bicuculline.

Having provided an anatomical description of the efferent projections of the dorsal midbrain anticonvulsant zone [Shehab S. et al. (1995) Neuroscience 65, 681-695], our purpose in the present study was to establish which outputs from this region are responsible for mediating the anticonvulsant and behavioural properties of dorsal midbrain activation. The ability of unilateral injections of bicuculline into the dorsal midbrain anticonvulsant zone to suppress tonic hindlimb extension in the electroshock model of epilepsy was tested before and after three different knife cuts: (i) a transection of ipsilateral descending projections on the same side as the injection of bicuculline; (ii) an identical cut except it was placed contralateral to the injection; (iii) a cut which transected rostral projecting fibres from the dorsal midbrain anticonvulsant zone including most ipsilateral ascending and crossed descending projections. A fourth group of operated control animals was included to establish a baseline for the schedule of repeated testing. Qualitative observations of behaviour were taken immediately prior to administration of the electroshocks. Unilateral transection of ipsilateral descending efferents prevented the suppression of electroshock-induced hindlimb extension by injections of bicuculline into the dorsal midbrain anticonvulsant zone on the same side of the brain. Both the control cuts on the opposite side of the brain and the rostral cuts were ineffective. Transection of the ipsilateral descending projection on the same side as the injection of bicuculline also reduced the incidence of defensive reactions induced by the GABA antagonist, including explosive motor behaviour, oral attack and vocalization. Damage to this projection on the opposite side had little effect on the expression of behavioural reactions, neither did transection of the ascending efferents. These data suggest that ipsilateral descending efferents are critical for the suppression of electroshock-induced extension of the hindlimbs and the expression of defensive reactions elicited by activation of the dorsal midbrain.

Some inhibitory neurons in the spinal cord develop c-fos-immunoreactivity after noxious stimulation.

In order to determine which types of spinal neuron produce c-fos in response to noxious stimulation, we have combined pre-embedding detection of c-fos-like immunoreactivity with post-embedding immunocytochemistry using antibodies against GABA and glycine, 2 h after subcutaneous injection of formalin into a hindpaw of anaesthetized rats. Throughout the spinal cord, the majority of c-fos-immunoreactive neurons (72-81%) did not possess GABA- or glycine-like immunoreactivity, while the remaining cells contained one or both types of immunoreactivity. In the superficial dorsal horn (laminae I and II) and dorsal white matter, between 14 and 20% of c-fos-immunoreactive neurons were GABA-immunoreactive, and some of these were also glycine-immunoreactive. A single neuron in lamina I in one animal was glycine- but not GABA-immunoreactive. In the remainder of the spinal cord, between 21 and 35% of the c-fos-immunoreactive cells were GABA- or glycine-immunoreactive, and the majority of these neurons contained both types of immunoreactivity. These results suggest that some inhibitory neurons in both the superficial and deep parts of the dorsal horn are activated by noxious stimuli. It is known that some of the cells which produce c-fos in response to noxious stimulation are projection neurons, with axons ascending to the brainstem or thalamus, however, because of the large number of c-fos-immunoreactive cells in the dorsal horn, it is likely that many are interneurons, and some of these are probably excitatory cells which use glutamate as a transmitter. It therefore appears that after noxious stimulation c-fos is produced in several types of spinal neuron, including projection cells and both excitatory and inhibitory interneurons.

Neurokinin-1 receptors on lumbar spinothalamic neurons in the rat.

In order to determine whether spinothalamic neurons in the lumbar spinal cord of the rat process neurokinin-1 (substance P) receptors, we injected cholera toxin B subunit into the thalamus and carried out dual-labelling immunocytochemistry to search for neurons that were immunoreactive with antibodies to cholera toxin and neurokinin-1 receptor. We examined 356 spinothalamic neurons in transverse sections and found that 35% of these were neurokinin-1 receptor-immunoreactive. Double-labelled cells made up the majority of the spinothalamic population in lamina I and the lateral spinal nucleus, and were also present in laminae III-V and the area around the central canal. On the side contralateral to the injection site, 77% of spinothalamic neurons in lamina I also showed neurokinin-1 receptor immunoreactivity, while 33% of those in laminae III-V and 14% of the ventromedial group possessed the receptor. Several of the double-labelled neurons with cell bodies in laminae III and IV had dendrites which could be followed dorsally into the superficial dorsal horn. These results indicate that substance P released from nociceptive primary afferents into the superficial dorsal horn is likely to act on spinothalamic tract neurons in lamina I, and also on those with cells bodies in laminae III-IV and long dorsal dendrites.

The types of neuron in spinal dorsal horn which possess neurokinin-1 receptors.

In order to provide further information about the types of spinal neuron which possess neurokinin-1 receptors, we have carried out pre-embedding immunocytochemistry on sections of rat lumbar spinal cord with an antiserum raised against a synthetic peptide corresponding to part of the sequence of the receptor, and combined this with post-embedding immunocytochemistry to detect GABA and glycine. Numerous neuronal cell bodies showing neurokinin-1 receptor-immunoreactivity were seen in lamina I, laminae III-VI, the lateral spinal nucleus and the area around the central canal. Most of the cells observed in lamina III were small and had relatively restricted dendritic trees which could often not be followed into lamina II, however some larger cells in laminae III and IV had dendrites which extended through lamina II and into lamina I. Cells of the latter type are likely to represent a major target of substance P released from small-diameter primary afferents in the superficial dorsal horn. The great majority (255 out of 283) of spinal neurons which possessed neurokinin-1 receptor-immunoreactivity, including all of those in lamina I, were not GABA- or glycine-immunoreactive, however a few cells in the deep part of the dorsal horn and the lateral spinal nucleus and several cells near the central canal were GABA-immunoreactive, and some of these were also glycine-immunoreactive. These results suggest that substance P acts through neurokinin-1 receptors mainly on excitatory neurons within the spinal cord.

Laser-assisted anastomosis of large-diameter vessels with the carbon dioxide laser.

A low-powered carbon dioxide laser was used to accomplish large-vessel anastomosis in growing minipigs. Results showed excellent patency, near-normal growth rates, and minimal foreign body response.

Peripheral axotomy of the rat mandibular trigeminal nerve leads to an increase in VIP and decrease of other primary afferent neuropeptides in the spinal trigeminal nucleus.

In the vasoactive intestinal polypeptide (VIP)-rich lumbosacral spinal cord, VIP increases at the expense of other neuropeptides after primary sensory nerve axotomy. This study was undertaken to ascertain whether similar changes occur in peripherally axotomised cranial sensory nerves. VIP immunoreactivity increased in the terminal region of the mandibular nerve in the trigeminal nucleus caudalis following unilateral section of the sensory root of the mandibular trigeminal nerve at the foramen orale. Other primary afferent neuropeptides (substance P, cholecystokinin and somatostatin) were depleted and fluoride-resistant acid phosphatase activity was abolished in the same circumscribed areas of the nucleus caudalis. The rise in VIP and depletion of other markers began 4 days postoperatively and was maximal by 10 days, these levels remaining unchanged up to 1 year postoperatively. VIP-immunoreactive cell bodies were absent from trigeminal ganglia from the unoperated side but small and medium cells stained intensely in the ganglia of the operated side after axotomy. These observations indicate that increase of VIP in sensory nerve terminals is a general phenomenon occurring in both cranial and spinal sensory terminal areas. The intense VIP immunoreactivity in axotomised trigeminal ganglia suggests that the increased levels of VIP in the nucleus caudalis are of peripheral origin, indicating a change in expression of neuropeptides within primary afferent neurons following peripheral axotomy.

A quantitative study of neuropeptide immunoreactive cell bodies of primary afferent sensory neurons following rat sciatic nerve peripheral axotomy.

Following peripheral axotomy, fluoride resistant acid phosphatase (FRAP) and most neuropeptides are depleted in the central terminals of axotomised nerves and reduced in their corresponding cell bodies (DRG) but vasoactive intestinal polypeptide (VIP) increases. The increase in VIP probably results from a change in gene expression in other ganglion cells which do not normally express VIP. A quantitative study was performed to investigate the proportion of DRG cells immunoreactive for different peptides at increasing times after sciatic nerve section. Retrograde fluorescent neuronal labelling of sciatic nerve cell bodies by injection of fast blue into the proximal stump was combined with unlabelled antibody immunohistochemistry for CGRP and VIP. The proportion of cells immunoreactive for these peptides was quantified between two and fourteen days post-axotomy. The number of VIP immunoreactive profiles increased significantly in the first 4 days post-axotomy, followed by a slight decrease before rising again. In contrast, the number of and CGRP-immunoreactive cell profiles declined to zero by 14 days post-axotomy. 4 days post-axotomy 50% of VIP positive cells were also immunoreactive for CGRP. There was neither colocalisation between VIP and FRAP nor between CGRP and FRAP. It is concluded that many peptidergic DRG cell bodies switch their expression of peptide to VIP after injury, whereas non-peptide-containing subpopulations do not.

Differential expression of fos-like immunoreactivity in the descending projections of superior colliculus after electrical stimulation in the rat.

In rodent, there is evidence that the orienting behaviour elicited by direct stimulation of the superior colliculus (SC) is partly mediated by contralateral descending projections, while avoidance-type behaviour is associated with ipsilateral descending projections. However, the identity of target structures in the brainstem which mediate these different behavioural responses is unknown. The c-fos immediate early gene is expressed polysynaptically in neurons in response to a wide range of extracellular stimuli, and hence has been proposed as a technique for mapping functional pathways. The purpose of this study was, therefore, to use the c-fos technique to investigate the functional specificity of brainstem regions which are innervated by the two main descending projections of the SC. Patterns of fos-like immunoreactivity (FLI) were observed throughout the brainstem following electrical stimulation of the SC in Urethane-anaesthetized rats. Previously, the electrical stimulation had been shown to elicit either approach-like or avoidance-like movement. The main results of this experiment were; (i) animals in which the stimulation elicited defensive behaviour had elevated levels of immunostaining in specific terminal areas of the ipsilateral descending projections, e.g. the ventrolateral midbrain/pontine reticular formation, the cuneiform area and rostral periaqueductal grey; (ii) there was no FLI expression in any of the terminal areas of the crossed descending projection, even in animals where the electrical stimulation elicited approach. Control experiments showed that the lack of expression in the crossed descending pathway was not due to the restricted range of stimulation parameters used in the main study, or to the effects of the anaesthetic. In conclusion, this experiment was able to identify likely substrates for the mediation of defensive reactions elicited by tectal stimulation. However, given the total lack of expression in a pathway which is known to be activated, it also provides further evidence that c-fos cannot simply be used as a high resolution neuronal activity marker for mapping functional pathways.

Vasoactive intestinal polypeptide (VIP) increases in the spinal cord after peripheral axotomy of the sciatic nerve originate from primary afferent neurons.

Following sciatic nerve axotomy, vasoactive intestinal polypeptide (VIP) immunoreactivity increases dramatically in the central terminal areas of the nerve whereas other primary afferent neuropeptides are depleted. The contribution of the peripheral nerve to VIP increases in the spinal cord was investigated by performing sciatic nerve section alone, dorsal rhizotomy of the lumbar roots, axotomy and rhizotomy in combination or section of other peripheral nerves terminating in the same segments as the sciatic nerve. VIP, and for comparison, substance P (SP), cholecystokinin (CCK), somatostatin (SOM), were localized in the lumbar spinal cord and corresponding sensory ganglia using unlabeled antibody immunohistochemistry. After sciatic nerve section, SP, CCK and SOM were depleted in the lumbar dorsal horn whereas VIP increased. After rhizotomy alone all neuropeptide staining including VIP was depleted; axotomy followed by rhizotomy produced the same result. Axotomy of other peripheral nerves terminating in the lumbar cord increased the area of neuropeptide depletion but correspondingly increased the area of VIP staining. A large proportion of small and medium diameter dorsal root ganglion cells were stained for VIP after nerve section or axotomy but not after rhizotomy alone. A radical change in neuropeptide metabolism of dorsal root ganglion cells occurs after peripheral axotomy, in the form of a marked increase in VIP synthesis. An intact dorsal root is necessary for increases in VIP in the spinal cord indicating the primary afferent origin of the response.

Anticonvulsant and behavioural effects of bicuculline injected into the mesencephalic locomoter region of rats.

Previous microinjection mapping studies in the mesencephalon established a significant association between the induction of locomotor activation and the suppression of tonic seizures in the electroshock model of epilepsy. The purpose of the present study was to see if this relationship also applies in an area of the brainstem commonly known as the mesencephalic locomotor region (MLR). The principal findings were the following. (i) Activation of extensive areas of the dorsal midbrain and tegmentum, including the MLR, by unilateral injections of the GABA antagonist bicuculline induced leg movements and suppressed the tonic component of electroshock-induced seizures. (ii) A highly significant correlation was observed between these two variables. (iii) In some cases, however, the induction of phasic leg movements was neither sufficient nor necessary for tonic seizure suppression. It is possible, therefore, that injection-elicited changes in tonic aspects of limb control may be more directly related to the suppression of tonic motor seizures in the electroshock model of epilepsy.

The origins of the sciatic nerve and changes in neuropeptides after axotomy: a double labelling study using retrograde transport of true blue and vasoactive intestinal polypeptide immunohistochemistry.

One month after sciatic nerve section, only dorsal root ganglion cells which take up True blue applied to the cut end of the nerve show vasoactive intestinal polypeptide immunoreactivity. This indicates that VIP expression is only in cells with damaged axons. Motor axons with True blue-positive perikarya in the ventral horn originate from the fourth to sixth lumbar segments whereas unmyelinated and small myelinated sensory nerves terminate in the third to fifth lumbar segments of the spinal cord.