Differential Joint-Specific Corticospinal Tract Projections within the Cervical Enlargement

The motor cortex represents muscle and joint control and projects to spinal cord interneurons and–in many primates, including humans–motoneurons, via the corticospinal tract (CST). To examine these spinal CST anatomical mechanisms, we determined if motor cortex sites controlling individual forelimb joints project differentially to distinct cervical spinal cord territories, defined regionally and by the locations of putative last-order interneurons that were transneuronally labeled by intramuscular injection of pseudorabies virus. Motor cortex joint-specific sites were identified using intracortical-microstimulation. CST segmental termination fields from joint-specific sites, determined using anterograde tracers, comprised a high density core of terminations that was consistent between animals and a surrounding lower density projection that was more variable. Core terminations from shoulder, elbow, and wrist control sites overlapped in the medial dorsal horn and intermediate zone at C5/C6 but were separated at C7/C8. Shoulder sites preferentially terminated dorsally, in the dorsal horn; wrist/digit sites, more ventrally in the intermediate zone; and elbow sites, medially in the dorsal horn and intermediate zone. Pseudorabies virus injected in shoulder, elbow, or wrist muscles labeled overlapping populations of predominantly muscle-specific putative premotor interneurons, at a survival time for disynaptic transfer from muscle. At C5/C6, CST core projections from all joint zones were located medial to regions of densely labeled last-order interneurons, irrespective of injected muscle. At C7/C8 wrist CST core projections overlapped the densest interneuron territory, which was located in the lateral intermediate zone. In contrast, elbow CST core projections were located medial to the densest interneuron territories, and shoulder CST core projections were located dorsally and only partially overlapped the densest interneuron territory. Our findings show a surprising fractionation of CST terminations in the caudal cervical enlargement that may be organized to engage different spinal premotor circuits for distal and proximal joint control

Formalin-induced behavioural hypersensitivity and neuronal hyperexcitability are mediated by rapid protein synthesis at the spinal level

Background: The mammalian target of rapamycin ( mTOR) is a key regulator of mRNA translation whose action can be inhibited by the drug rapamycin. Forms of long-term plasticity require protein synthesis and evidence indicates that mRNA in dendrites, axon terminals and cell bodies is essential for long-term synaptic plasticity. Specific to pain, shifts in pain thresholds and responsiveness are an expression of neuronal plasticity and this likely contributes to persistent pain. We investigated this by inhibiting the activity of mTOR with rapamycin at the spinal level, of rats that were subjected to the formalin test, using both behavioural and electrophysiological techniques.Results: For in vivo electrophysiology, Sprague Dawley rats were fully anaesthetised and single-unit extracellular recordings were obtained from lamina V wide dynamic range (WDR) dorsal horn spinal neurones at the region where input is received from the hind paw. Neuronal responses from naive rats showed that rapamycin-sensitive pathways were important in nociceptive-specific C-fibre mediated transmission onto WDR neurones as well mechanically-evoked responses since rapamycin was effective in attenuating these measures. Formalin solution was injected into the hind paw prior to which, rapamycin or vehicle was applied directly onto the exposed spinal cord. When rapamycin was applied to the spinal cord prior to hind paw formalin injection, there was a significant attenuation of the prolonged second phase of the formalin test, which comprises continuing afferent input to the spinal cord, neuronal hyperexcitability and an activated descending facilitatory drive from the brainstem acting on spinal neurones. In accordance with electrophysiological data, behavioural studies showed that rapamycin attenuated behavioural hypersensitivity elicited by formalin injection into the hind paw.Conclusion: We conclude that mTOR has a role in maintaining persistent pain states via mRNA translation and thus protein synthesis. We hypothesise that mTOR may be activated by excitatory neurotransmitter release acting on sensory afferent terminals as well as dorsal horn spinal neurones, which may be further amplified by descending facilitatory systems originating from higher centres in the brain

The troika host-pathogen-extrinsic factors in tuberculosis: modulating inflammation and clinical outcomes

The Troika Host-Pathogen-Extrinsic Factors in Tuberculosis: Modulating Inflammation and Clinical OutcomesThe already enormous burden caused by tuberculosis (TB) will be further aggravated by the association of this disease with modern epidemics, as human immunodeficiency virus and diabetes. Furthermore, the increasingly aging population and the wider use of suppressive immune therapies hold the potential to enhance the incidence of TB. New preventive and therapeutic strategies based on recent advances on our understanding of TB are thus needed. In particular, understanding the intricate network of events modulating inflammation in TB will help to build more effective vaccines and host-directed therapies to stop TB. This review integrates the impact of host, pathogen, and extrinsic factors on inflammation and the almost scientifically unexplored complexity emerging from the interactions between these three factors. We highlight the exciting data showing a contribution of this troika for the clinical outcome of TB and the need of incorporating it when developing novel strategies to rewire the immune response in TB.HN-B acknowledges the receipt of research scholarships from Bolsa D. Manuel de Mello and the Portuguese Society for Pneumology. NO acknowledges FCT IF/00474/2014. SG is funded by the European Research Council (grant number 309540-EVODRTB); the Swiss National Science Foundation (grant number 310030_166687) SystemsX.ch. IC lab is financed by Ministerio de Economía y Competitividad (Spanish Government) research grant SAF2013-43521-R, SAF2016- 77346-R, and PROMETEO/2016/122 from Generalitat Valenciana and the European Research Council (ERC) (638553-TB-ACCELERATE). The MS lab is financed by FEDER—Fundo Europeu de Desenvolvimento Regional funds through the COMPETE 2020—Operacional Programme for Competitiveness and Internationalisation (POCI), Portugal 2020, and by Portuguese funds through FCT in the framework of the project “Institute for Research and Innovation in Health Sciences” (POCI-01-0145-FEDER-007274). MS is an FCT Principal Investigator. Some graphical elements in the figures were designed by kjpargeter/Freepik. The funding agencies had no role in the design of the manuscriptinfo:eu-repo/semantics/publishedVersio

Malaria prevention in north-eastern Tanzania: patterns of expenditure and determinants of demand at the household level

OBJECTIVE: This study aims to provide a better understanding of the amounts spent on different malaria prevention products and the determinants of these expenditures. METHODS: 1,601 households were interviewed about their expenditure on malaria mosquito nets in the past five years, net re-treatments in the past six months and other expenditures prevention in the past two weeks. Simple random sampling was used to select villages and streets while convenience sampling was used to select households. Expenditure was compared across bed nets, aerosols, coils, indoor spraying, using smoke, drinking herbs and cleaning outside environment. FINDINGS: 68% of households owned at least one bed net and 27% had treated their nets in the past six months. 29% were unable to afford a net. Every fortnight, households spent an average of US $0.18 on nets and their treatment, constituting about 47$0.21). Factors positively related to expenditure were household wealth, years of education of household head, household head being married and rainy season. Poor quality roads and living in a rural area had a negative impact on expenditure. CONCLUSION: Expenditure on bed nets and on alternative malaria prevention products was comparable. Poor households living in rural areas spend significantly less on all forms of malaria prevention compared to their richer counterparts. Breaking the cycle between malaria and poverty is one of the biggest challenges facing malaria control programmes in Africa

CST termination patterns from joint-specific motor cortex sites.

<p>Anterograde tracer injections were made into joint-specific sites in the motor cortex (A4; color code indicated in inset). Injection sites are shown overlaid on the joint probability map from Fig. 2G. Lightly shaded blue and green circles for wrist and shoulder respectively indicate injection sites where the dominant response and termination pattern were of the same group, yet was accompanied by a second smaller joint response at threshold. A1–3. Micrographs (inverted fluorescence images) of single sections showing CST labeling produced from injected (A1) shoulder, (A2) elbow, and (A3) wrist sites. B. Distribution of CST labeling at C5/C6. Average heatmaps for motor cortex shoulder elbow, and wrist sites (B1–B3). Black contours indicate the boundary of the high-density labeled region (≥60%) based on the averaged heatmap. Gray contours show high-density labeled region from each individual animal. B4 shows overlap of high-density (filled shapes) and low-density (10%; open shapes). Shading and line color according to the inset. C. Same as B, but for C7/C8. Color scale represents number of pixels per mm². Scale bar = 500 µm.</p

Segmental locations of last-order interneurons after PRV injections into individual muscle groups and CST-interneuron topographic relationship.

<p>(A1–A3) Overlaid C7–C8 section images processed in Neurolucida showing positions of individual last-order interneurons from PRV injected into the deltoids, biceps and the wrist extensor compartments in representative animals. B1–B3. Density heat map produced from all labeled sections at cervical levels C5–C6. C1–C3. Density heat map produced from all labeled sections at cervical levels C7–C8. Overlaid onto heat maps are shoulder, elbow and wrist high-density (black) and low-density (gray) CST termination contours. Color scale represents cells per mm². Size bar = 500 µm.</p