Role of Oxysterols in Ocular Degeneration Mechanisms and Involvement of P2X7 Receptor

Ocular degeneration, including cataracts, glaucoma, macular degeneration, and diabetic retinopathy, is a major public health challenge, as it affects the quality of life of millions of people worldwide and, in its advanced stages, leads to blindness. Ocular degeneration, although it can affect different parts of the eye, shares common characteristics such as oxysterols and the P2X7 receptor. Indeed, oxysterols, which are cholesterol derivatives, are associated with ocular degeneration pathogenesis and trigger inflammation and cell death pathways. Activation of the P2X7 receptor is also linked to ocular degeneration and triggers the same pathways. In age-related macular degeneration, these two key players have been associated, but further studies are needed to extrapolate this interrelationship to other ocular degenerations.

P2X7-Receptor Pathway Involvement in the Anti-Inflammatory Activity of Medicinal Plants

Medicinal plants used in European folk medicine attached to Lamiales, Gentianales or Asterales orders are used to treat inflammatory disorders. Many targets have been identified but to date, implication of purinergic receptor P2X7 activation has not yet been investigated. We managed to evaluate the protective effect on P2X7 activation by plant extracts used as anti-inflammatory in European folk medicine by the YO-PRO-1 uptake dye in vitro bioassay. Results revealed that among our selected plants, species from Scrophularia and Plantago genus were able to decrease significantly P2X7 activation (>50 % at 0.1 and 1 μg/mL). UPLC/MS, dereplication and metabolomic analysis of Scrophularia extracts, allowed us to identify the cinnamoyl-iridoid harpagoside as putative inhibitor of P2X7 activation. These results open a new research field regarding the anti-inflammatory mechanism of cinnamoyl-iridoids bearing plants, which may involve the P2X7 receptor.

One-year mortality in lung cancer in France according to key time points of care pathways

Background

It is unclear whether delays in care affect prognosis of patients with lung cancer. The primary objective of this study was to describe the care pathway of patients diagnosed with lung cancer in a French region. Secondary objectives were to identify markers associated with 1) time from imaging to treatment, and 2) with one-year survival.

Methods

In a retrospective cohort study, clinical data from multidisciplinary team meetings (MTM) for all incident lung cancer cases discussed in 2018 in one French region were matched with medico-administrative data from the National Health Insurance Database. Care pathway time intervals were estimated for small cell lung cancer (SCLC), resected non-small cell lung cancer (NSCLC) and unresected NSCLC. Factors associated with delay in the care pathway were identified using linear regression; 1-year survival was analysed using Cox modelling.

Results

A total of 685 patients were included. Median time between imaging and treatment was 49 days (q1-q3: 33–73), and was lower in cases of metastatic disease, SCLC, and private care. At one year, 48% had died (resected NSCLC 12%). In unresected NSCLC, time from diagnostic imaging to first treatment <49 days was associated with a higher risk of death. Time intervals were similar in patients with squamous cell carcinomaversusadenocarcinoma or undifferentiated carcinoma.

Discussion

Time intervals in the care pathways of lung cancer were similar to previous reports, confirming the robustness of retrospective databases. In unresectable NSCLC, rapid care was not associated with better survival.

Cocktail Effect of Endocrine Disrupting Chemicals: Application to Chlorpyrifos in Lavender Essential Oils

Chlorpyrifos is a pesticide that is toxic to human health and has been banned for the past decade. Due to its persistent and bioaccumulative properties, chlorpyrifos is still present in soil. Pregnant women can be exposed to chlorpyrifos through drinking water and herbal products, such as essential oils (EOs), resulting in adverse effects to the mother and fetus. Our objective was to evaluate and compare the potential endocrine disrupting effects of chlorpyrifos "free" or in contaminated lavender EO. We studied the release of four hormones and the activation of the P2X7 cell death receptor in human placental JEG-Tox cells as key biomarkers of endocrine toxicity for pregnant women (hPlacentox assay). We observed that "free" chlorpyrifos disrupted placental hormones and activated the P2X7 receptor, whereas chlorpyrifos in lavender EO disrupted only the placental hormones. We confirm that chlorpyrifos can be classified as an endocrine disrupting chemical (EDC) for pregnant women and point out that its endocrine disrupting effect may not be apparent when present in lavender EOs. Our results reveal the existence of specific reverse cocktail effects that may have protective properties against EDCs.

Forskolin Induces Endocrine Disturbance in Human JEG-3 Placental Cells

Forskolin, used in folk medicine since ancient times, is now available as a dietary supplement, with an indication as a fat burner and appetite suppressant. However, the safety of forskolin is poorly documented especially for pregnant women. The question that we raised is what about the safety of forskolin in pregnant women? As the placenta, an endocrine organ, is the key organ of pregnancy, we evaluated the in vitro placental toxicity of forskolin. We focused first on the activation of a P2X7 degenerative receptor as a key biomarker for placental toxicity, and second on steroid and peptide hormonal secretion. We observed that forskolin activated P2X7 receptors and disturbed estradiol, progesterone, hPL and hyperglycosylated hCG secretion in human placental JEG-Tox cells. To the best of our knowledge, we highlighted, for the first time, that forskolin induced endocrine disturbance in placental cells. Forskolin does not appear to be a safe product for pregnant women and restrictions should be taken.

Evaluation of Placental Toxicity of Five Essential Oils and Their Potential Endocrine-Disrupting Effects

Pregnant women may use EOs in case of morning sickness, nausea, stress management, etc. Little is known about the potential danger that EOs represent for the placenta and therefore for the pregnancy. Our aim was to explore and compare the placental toxicity and potential endocrine disrupting effects of niaouli, orange, tea tree, wintergreen and ylang-ylang EOs, and their key compounds: 4-terpineol, 1,8-cineol, limonene, methyl salicylate and benzyl salicylate. We studied the release of four hormones and the activation of P2X7 receptor in JEG-Tox human placental cells as key biomarkers for endocrine toxicity. We observed that niaouli, orange, tea tree, wintergreen and ylang-ylang EOs and their key components disrupted at least one of the studied hormones but none of them activated the P2X7 cell death receptor. The tested EOs appear then to be more hormonal modulators rather than EDCs in human placental cells. The hormonal effects observed with the key components were very different from those observed with the EOs. EOs are very complex mixtures, and it is essential to study whole EOs rather than their components individually in safety assessment.

JEG-3 placental cells in toxicology studies: a promising tool to reveal pregnancy disorders

Placental alterations are responsible for adverse pregnancy outcomes like preeclampsia and intrauterine growth restriction. And yet, placenta toxicology has not become a fully-fledged toxicology field. Because placenta is very often seen only as a barrier between the mother and the fetus, there is a lack and therefore a need for an experimental human model with technical recommendations to study placenta toxicology. In vitro approaches are recommended in experimental toxicology as they focus on a specific biological process and yield high-throughput screening methods. In the present study, we first established incubation conditions to preserve signatures of the human JEG-3 cell line identity while enabling toxicity detection. JEG-3 cells prepared in our incubation conditions were renamed JEG-Tox cells. As placental alterations are mainly triggered by uncontrolled apoptosis, we second used known apoptotic agents pregnant women are exposed to, to check that JEG-Tox cells can trigger apoptosis. Ethanol, bisphenol F, quinalphos, 4,4'-DDT, benzalkonium chloride, phenoxyethanol, propylparaben, and perfluorooctanic acid all induced chromatin condensation in JEG-Tox cells. Our incubation conditions allow JEG-Tox cells to keep placental cell identity and to respond to toxic chemicals. JEG-Tox cells are a pertinent model for placenta toxicology and could be used to better understand pregnancy alterations.

In Vitro Chemopreventive Potential of Phlorotannins-Rich Extract from Brown Algae by Inhibition of Benzo[a]pyrene-Induced P2X7 Activation and Toxic Effects

Phlorotannins are polyphenols occurring exclusively in some species of brown algae, known for numerous biological activities, e.g., antioxidant, antiproliferative, antidiabetic, and antiallergic properties. Their effects on the response of human lung cells to benzo[a]pyrene (B[a]P) has not been characterized. Our objective was to in vitro evaluate the effects of a phlorotannin-rich extract obtained from the brown algae Ascophyllum nodosum and Fucus vesiculosus on B[a]P cytotoxic effects. The A549 cell line was incubated with B[a]P for 48 and 72 h in the presence or absence of the brown algae extract. Cytochrome P450 activity, activation of P2X7 receptor, F-actin disorganization, and loss of E-cadherin expression were assessed using microplate cytometry and fluorescence microscopy. Relative to control, incubation with the brown algae extract was associated with lower B[a]P-induced CYP1 activity, lower P2X7 receptor activation, and lower reactive oxygen species production. The brown algae extract inhibited the alterations of F-actin arrangement and the downregulation of E-cadherin expression. We identified a phlorotannins-rich extract that could be deeper investigated as a cancer chemopreventive agent to block B[a]P-mediated carcinogenesis.

SARS-CoV-2 vs. SARS-CoV-1 management: antibiotics and inflammasome modulators potential

The coronavirus SARS-CoV-2 at the origin of COVID-19 shares more than 70% genetic similarity with SARS-CoV-1 that was at the origin of 2003 SARS. Infection-associated symptoms are very similar between SARS and COVID-19 diseases and are the same as community-acquired pneumonia symptoms. Antibiotics were empirically given to SARS patients in the early stages of the pathology whereas a different strategy has been decided in the management of COVID-19 pandemic with a worldwide shutdown. The cytokine storm, both identified in SARS and COVID-19 severe cases, is generated through inflammasome activation, which opens therapeutic perspectives to counteract the pathogenic inflammation. As corticoids have numerous side effects that limit their use, focusing on anti-inflammasome agents could represent a safer alternative for patients with severe COVID-19.

Lipidomic analysis of human corneal epithelial cells exposed to ocular irritants highlights the role of phospholipid and sphingolipid metabolisms in detergent toxicity mechanisms

Detergent chemicals, widely used in household products, in pharmaceutical, medical, cosmetic and industrial fields, have been linked to side effects and involved in several eye diseases. On the ocular surface, detergents can interfere with the corneal epithelium, the most superficial layer of the cornea, representing a line of defence against external aggression. Despite its major role in numerous biological functions, there is still little data regarding disruption of lipid homeostasis induced by ocular irritants. To this purpose, a lipidomic analysis using UPLC-HRMS/MS-ESI ± was performed on human corneal epithelial (HCE) cells incubated with three widely known ocular irritants: benzalkonium chloride (BAK), sodium lauryl sulfate (SLS) and Triton X-100 (TXT). We found that these ocular irritants lead to a profound modification of the HCE cell lipidome. Indeed, the cell content of ceramide species increased widely while plasmalogens containing polyunsaturated fatty acid species, especially docosahexaenoic acids, decreased. Furthermore, these irritants upregulated the activity of phospholipase A₂. The present study demonstrates that BAK, SLS and TXT induced disruption of the cell lipid homeostasis, highlighting that lipids mediate inflammatory and cell death processes induced by detergents in the cornea. Lipidomics may thus be regarded as a valuable tool to investigate new markers of corneal damage.

In Situ Gelling Ophthalmic Drug Delivery System for the Optimization of Diagnostic and Preoperative Mydriasis: In Vitro Drug Release, Cytotoxicity and Mydriasis Pharmacodynamics

Mydriasis is required prior to many eye examinations and ophthalmic surgeries. Nowadays, phenylephrine hydrochloride (PHE) and tropicamide (TPC) are extensively used to induce mydriasis. Several pharmaceutic dosage forms of these two active ingredients have been described. However, no optimal therapeutic strategy has reached the market. The present work focuses on the formulation and evaluation of a mucoadhesive ion-activated in situ gelling delivery system based on gellan gum and hydroxyethylcellulose (HEC) for the delivery of phenylephrine and tropicamide. First, in vitro drug release was studied to assess appropriate sustained drug delivery on the ocular surface region. Drug release mechanisms were explored and explained using mathematical modeling. Then, in situ gelling delivery systems were visualized using scanning electron microscopy illustrating the drug release phenomena involved. Afterward, cytotoxicity of the developed formulations was studied and compared with those of commercially available eye drops. Human epithelial corneal cells were used. Finally, mydriasis intensity and kinetic was investigated in vivo. Mydriasis pharmacodynamics was studied by non-invasive optical imaging on vigilant rabbits, allowing eye blinking and nasolacrimal drainage to occur physiologically. In situ gelling delivery systems mydriasis profiles exhibited a significant increase of intensity and duration compared with those of conventional eye drops. Efficient mydriasis was achieved following the administration of a single drop of in situ gel reducing the required amount of administered active ingredients by four- to eight-fold compared with classic eye drop regimen.

Cytotoxic and Anti-Inflammatory Effects of Ent-Kaurane Derivatives Isolated from the Alpine Plant Sideritis hyssopifolia

This paper reports the isolation and structural characterization of four new ent-kaurane derivatives from the Lamiaceae plant Sideritis hyssopifolia. Planar structures and relative configurations were determined using both mass spectrometry and nuclear magnetic resonance (1D and 2D). Absolute configurations were determined by comparing experimental and theoretical electronic circular dichroism spectra. The cytotoxic and microbial activities of all new compounds were tested. Compounds that were non-cytotoxic were further evaluated for anti-inflammatory activity.

Boys' and girls' latent profiles of behavior and social adjustment in school: Longitudinal links with later student behavioral engagement and academic achievement?

Using a person-centered approach, this study identified profiles of students exhibiting behavior and social adjustment problems in school. We conducted Latent Profile Analysis to identify these subgroups in a sample of 582 fifth and sixth graders. We found four profiles among girls-well-adjusted girls (66.10%); girls displaying externalizing behaviors and student-teacher conflict (4.75%); girls exhibiting internalizing behaviors and isolation from peers (10.17%); and girls with student-teacher nonclose interactions and nonprosocial behaviors toward peers (18.98%). We found three profiles among boys-well-adjusted boys (78.05%); boys displaying externalizing behaviors and student-teacher conflict (10.10%); and boys with externalizing, internalizing, and social problems with peers and teachers (11.85%). Next, we investigated longitudinal associations between these profiles and student behavioral engagement and academic achievement. Path analysis revealed that, compared to students with a well-adjusted profile, having a non-adjusted profile was associated with negative changes in teacher-reported behavioral engagement. Girls with an Externalizing Problem/Student-teacher Conflict profile or an Internalizing Problems/Peer Isolation profile also showed negative changes throughout the school year in their self-reported behavioral engagement and in academic achievement. We discussed these results and their practical implications in light of existing literature.

Lipid deregulation in UV irradiated skin cells: Role of 25-hydroxycholesterol in keratinocyte differentiation during photoaging

Skin photoaging due to UV irradiation is a degenerative process that appears more and more as a growing concern. Lipids, including oxysterols, are involved in degenerative processes; as skin cells contain various lipids, the aim of our study was to evaluate first, changes in keratinocyte lipid levels induced by UV exposure and second, cellular effects of oxysterols in cell morphology and several hallmarks of keratinocyte differentiation. Our mass spectrometry results demonstrated that UV irradiation induces changes in lipid profile of cultured keratinocytes; in particular, ceramides and oxysterols, specifically 25-hydroxycholesterol (25-OH), were increased. Using holography and confocal microscopy analyses, we highlighted cell thickening and cytoskeletal disruption after incubation of keratinocytes with 25-OH. These alterations were associated with keratinocyte differentiation patterns: autophagy stimulation and intracellular calcium increase as measured by cytofluorometry, and increased involucrin level detected by immunocytochemistry. To conclude, oxysterol deregulation could be considered as a common marker of degenerative disorders. During photoaging, 25-OH seems to play a key role inducing morphological changes and keratinocyte differentiation.

A fast and reproducible cell- and 96-well plate-based method for the evaluation of P2X7 receptor activation using YO-PRO-1 fluorescent dye

The YO-PRO-1 assay provides a quantitative estimation of P2X7 receptor activation. P2X7 receptor is associated to pathological conditions including infectious, inflammatory, neurological, musculoskeletal disorders, pain and cancer. Most primary cells and cell lines from diverse origin may be used thanks to the ubiquitous distribution of P2X7 receptor. To study the activation of P2X7 receptor by chemicals or biological agents, we established a microplate-based cytometry protocol to accurately and rapidly quantify the activation of P2X7 receptor that leads to the formation of large pores in cell membranes. The YO-PRO-1 assay is based on the ability of cells to incorporate and bind YO-PRO-1 dye to DNA after activation of P2X7 receptor through pore formation. Cells are seeded in 96-well plates and incubated with the compound being tested for the appropriate time. The microplate is then incubated for 10 min with YO-PRO-1 staining solution. After the 10 min staining time, fluorescence signal is read using a microplate reader in 1 min. This procedure is easier and requires less handling steps than flow cytometry. 96-well plate based YO-PRO-1 assay is a reproducible and fast method to study both P2X7 receptor activation by toxic agents at subnecrotic concentrations and P2X7 receptor inhibition by antagonists.

How increasing the effect of rTMS in the treatment of auditory hallucinations in schizophrenia?

Repetitive transcranial magnetic stimulation (rTMS) shows a high inter-subjects variability in the efficacy of treatment of auditory verbal hallucinations (AVH) in schizophrenia. The aim of this presentation is to demonstrate the involvement of several factors in the efficacy of rTMS such as the frequency of stimulation, the placebo effect and the brain morphology underlying the target of stimulation.

Methods

A meta-analysis was conducted to determine the effect sizes of placebo effect in 21 controlled studies on rTMS in the treatment of AVH in schizophrenia. MRI was also acquired in patients treated by rTMS to evaluate the scalp to cortex distances (SDCs) and the gray matter densities (GMDs) at the target of stimulation. Finally, we evaluated the efficacy of high (20 Hz) frequency stimulation in a controlled placebo study.

Results

Weak or no placebo effect in the control groups led to reveal a superiority of active rTMS over sham rTMS in the treatment of AVH. Clinical efficacy of rTMS was also correlated with the SCD or the GMD at the region of the target stimulation. Finally, we also demonstrated that more responders were observed after 2 weeks in the active group treated by 20 Hz than in the placebo group.

Conclusion

We clearly demonstrated that several factors such as high frequency, the placebo effect, anatomical cortical variations can impact on the efficacy of rTMS. These results fundamentally inform the design and the method of further controlled studies, particularly with respect to studies of rTMS in the treatment of AVH.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Poloxamer bioadhesive hydrogel for buccal drug delivery: Cytotoxicity and trans-epithelial permeability evaluations using TR146 human buccal epithelial cell line

A salbutamol sulfate (SS)-Poloxamer bioadhesive hydrogel specially developed for buccal administration was investigated by studying interactions with TR146 human buccal epithelium cells (i.e. cellular toxicity (i) and trans-epithelial SS diffusion (ii)). The assessment of cell viability (MTT, Alamar Blue), membrane integrity (Neutral Red), and apoptosis assay (Hoechst 33342), were performed and associated to Digital Holographic Microscopy analysis. After the treatment of 2h, SS solution induced drastic cellular alterations that were prevented by hydrogels in relation with the concentrations of poloxamer and xanthan gum. The formulation containing P407 19%/P188 1%/Satiaxane 0.1% showed the best tolerance after single and multiple administrations and significantly reduced the trans-epithelial permeability from 5.00±0.29 (×10(3)) (SS solution) to 1.83±0.22 cm/h. Digital Holographic Microscopy images in good agreement with the viability data confirmed the great interest of this direct technique. In conclusion, the proposed hydrogels represent a safe and efficient buccal drug delivery platform.

Distinct brain signatures of content and structure violation during action observation

Sentences, musical phrases and goal-directed actions are composed of elements that are linked by specific rules to form meaningful outcomes. In goal-directed actions including a non-canonical element or scrambling the order of the elements alters the action's content and structure, respectively. In the present study we investigated event-related potentials of the electroencephalographic (EEG) activity recorded during observation of both alterations of the action content (obtained by violating the semantic components of an action, e.g. making coffee with cola) and alterations of the action structure (obtained by inverting the order of two temporally adjacent pictures of sequences depicting daily life actions) interfering with the normal flow of the motor acts that compose an action. Action content alterations elicited a bilateral posterior distributed EEG negativity, peaking at around 400 ms after stimulus onset similar to the ERPs evoked by semantic violations in language studies. Alteration of the action structure elicited an early left anterior negativity followed by a late left anterior positivity, which closely resembles the ERP pattern found in language syntax violation studies. Our results suggest a functional dissociation between the processing of action content and structure, reminiscent of a similar dissociation found in the language or music domains. Importantly, this study provides further support to the hypothesis that some basic mechanisms, such as the rule-based structuring of sequential events, are shared between different cognitive domains.

Role of the medial part of the intraparietal sulcus in implementing movement direction

The contribution of the posterior parietal cortex (PPC) to visually guided movements has been originally inferred from observations made in patients suffering from optic ataxia. Subsequent electrophysiological studies in monkeys and functional imaging data in humans have corroborated the key role played by the PPC in sensorimotor transformations underlying goal-directed movements, although the exact contribution of this structure remains debated. Here, we used transcranial magnetic stimulation (TMS) to interfere transiently with the function of the left or right medial part of the intraparietal sulcus (mIPS) in healthy volunteers performing visually guided movements with the right hand. We found that a "virtual lesion" of either mIPS increased the scattering in initial movement direction (DIR), leading to longer trajectory and prolonged movement time, but only when TMS was delivered 100-160 ms before movement onset and for movements directed toward contralateral targets. Control experiments showed that deficits in DIR consequent to mIPS virtual lesions resulted from an inappropriate implementation of the motor command underlying the forthcoming movement and not from an inaccurate computation of the target localization. The present study indicates that mIPS plays a causal role in implementing specifically the direction vector of visually guided movements toward objects situated in the contralateral hemifield.

Role of the Ipsilateral Primary Motor Cortex in Controlling the Timing of Hand Muscle Recruitment

The precise contribution of the ipsilateral primary motor cortex (iM1) to hand movements remains controversial. To address this issue, we elicited transient virtual lesions of iM1 by means of transcranial magnetic stimulation (TMS) in healthy subjects performing either a grip-lift task or a step-tracking task with their right dominant hand. We found that, irrespective of the task, a virtual lesion of iM1 altered the timing of the muscle recruitment. In the grip-lift task, this led to a less coordinated sequence of grip and lift movements and in the step-tracking task, to a perturbation of the movement trajectory. In the step-tracking task, we have demonstrated that disrupting iM1 activity may, depending on the TMS delay, either advance or delay the muscle recruitment. The present study suggests that iM1 plays a critical role in hand movements by contributing to the setting of the muscle recruitment timing, most likely through either inhibitory or facilitatory transcallosal influences onto the contralateral M1 (cM1). iM1 would therefore contribute to shape precisely the muscular command originating from cM1.

Anatomical study of the paraspinal approach to the lumbar spine

The original description of the paraspinal posterior approach to the lumbar spine was for spinal fusion, especially regarding lumbosacral spondylolisthesis treatment. In spite of the technical details described by Wiltse, exact location of the area where the sacrospinalis muscle has to be split remains somewhat unclear. The goal of this study was to provide topographic landmarks to facilitate this surgical approach. Thirty cadavers were dissected in order to precisely describe the anatomy of the trans-muscular paraspinal approach. The level of the natural cleavage plane between the multifidus and the longissimus part of the sacrospinalis muscle was noted and measurements were done between this level and the midline at the level of the spinous process of L4. A natural cleavage plane between the multifidus and the longissimus part of the sacrospinalis muscle was present in all cases. There was a fibrous separation between the two muscular parts in 55 out of 60 cases. The mean distance between the level of the cleavage plane and the midline was 4 cm (2.4-5.5 cm). In all cases, small arteries and veins were present, precisely at the level of the cleavage plane. We found it possible to easily localize the anatomical cleavage plane between the multifidus part and the longissimus part of the sacrospinalis muscle. First the superficial muscular fascia is opened near the midline, exposing the posterior aspect of the sacrospinalis muscle. Then, the location of the muscular cleft can be found by identifying the perforating vessels leaving the anatomical inter-muscular space.

Kinematically Specific Interhemispheric Inhibition Operating in the Process of Generation of a Voluntary Movement

Unilateral hand movements are accompanied by a transient decrease in corticospinal (CS) excitability of muscles in the opposite hand. However, the rules that govern this phenomenon are not completely understood. We measured the amplitude of motor evoked potentials (MEP) in the left first dorsal interosseus (FDI) elicited by transcranial magnetic stimulation (TMS) of the primary motor cortex in order to assess CS excitability changes that preceded eight possible combinations of unilateral and bilateral index finger movements with different right hand positions. Left FDI MEP amplitude (MEP(Left FDI)) increased when this muscle acted as an agonist and tended to decrease when it was an antagonist. Additionally, MEP(Left FDI) decreased substantially before right index finger abduction (a movement mediated by the right FDI) when both hands were lying flat (a movement mirroring left index finger abduction) but not when the right hand was turned at 90 degrees or flat with the palm up. Therefore, CS excitability of the resting FDI was differentially modulated depending on the direction of the opposite index finger movement, regardless of muscles engaged in the task. These results indicate that inhibitory interactions preceding unilateral finger movements are determined by movement kinematics possibly to counteract the default production of mirror motions.

The Influence of Hand Posture on Corticospinal Excitability during Motor Imagery: A Transcranial Magnetic Stimulation Study

In order to study the interaction between proprioceptive information and motor imagery, we herein investigate how compatible and incompatible postural signals influence corticospinal excitability during the mental simulation of hand movements. Subjects were asked to imagine themselves joining the tips of the thumb and the little finger while they maintained one of the two following hand postures: posture A (PA, compatible), little finger, index and thumb extended, the remaining fingers flexed; or posture B (PB, incompatible), index and thumb extended, other fingers flexed. All subjects rated the imagined finger opposition movements as easier to perform when the hand was kept in PA than in PB (P < 0.01) and the correlation between the duration of motor imagery and movement execution was also higher for PA than PB (P < 0.01). For each posture, motor evoked potentials (MEPs) elicited by focal transcranial magnetic stimulation (TMS) of the left motor cortex were recorded from the right opponens pollicis muscle during both motor imagery (MI) and rest (R) conditions. MEP area varied according to the hand posture: PA induced a higher increase in corticospinal excitability, when compared with PB. These results indicate that the actual limb posture affects the process of motor imagery. The source of this postural modulation effect is discussed.

Long-latency motor evoked potentials in congenital hemiplegia

OBJECTIVE

To investigate long-latency motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation in congenital hemiplegia (CH) and to seek for correlation with paretic hand movement deficits.

METHODS

MEPs were recorded from the first dorsal interosseous of both hands in 12 CH patients and 12 age-matched controls; dexterity and upper limb function were quantitatively assessed in both groups.

RESULTS

In CH patients, long-latency MEPs, occurring much later than the commonly reported MEPs, were frequently observed in the paretic and non-paretic hands. Four distinct groups of long-latency MEPs were found, each cluster being identified by its mean latency, namely 35, 85, 160 and 225 ms. The residual dexterity of the paretic hand was correlated with the presence of contralateral MEPs with a 20 and 225 ms latency and was negatively correlated with ipsilateral MEPs, irrespective of their latency. In controls, only few MEPs with a latency of 225 ms were found in 4 out of 12 subjects.

CONCLUSIONS

The pattern of MEPs found in CH patients differs dramatically from that reported in adult stroke patients, suggesting that long-latency MEPs are a rather distinctive consequence of early corticospinal lesions. The hypothesis that a given cluster of long-latency MEPs is mediated by a particular pathway appears very unlikely. Rather, we suggest that an exacerbation of cortical and/or spinal excitability is at the origin of these long-latency MEPs.

[Spinal locations of pigmented villonodular synovitis: case report and review of the literature]

Pigmented villonodular synovitis is rarely observed in the spine: less than thirty cases have been reported. We report a new case observed in the cervical spine and review the pertinent literature. The clinical and radiological presentation of these forms of villonodular synovitis is non-specific and similar to that if primary or secondary spinal tumors. Histology is indispensable for certain diagnosis. Complete surgical resection is the treatment of choice but with a risk of recurrence to the order of 20%. Non-surgical treatments have not proven to be effective for spinal villonodular synovitis. Regular MRI surveillance is indicated. Spinal localizations may raise difficult technical problems in the event of recurrence.

[Plasticity of motor maps in primates: recent advances and therapeutical perspectives]

In the past decade, there have been considerable advances in understanding the neuronal bases of sensory and motor map reorganisation in adults and it is now clear that cortical representations are not invariant and stable, but rather, are dynamic and can continuously be modified. In human subjects, substantial advances in this field have been possible because of the spectacular development of non-invasive imaging and brain stimulation techniques. This review addresses specific questions about the capacity of motor maps in adult primates, including man, to change in response to behaviourally relevant experiences or as a result of central or peripheral lesion. The first part of this review deals with recent progress in understanding the role of the primary motor cortex (M1) in both motor control and cognition. The organisation and function of multiple "non-primary" motor areas located rostrally to the primary motor cortex and in the cingulate cortex are also discussed. This review then focuses on advances made in understanding motor cortex plasticity in different conditions. Firstly, since representations in M1 have been shown to change after motor learning, the contribution of M1 in motor learning has been insinuated; arguments against and in favour of this view are discussed. In addition, data suggesting that intracortical circuitry of M1 may play a role in map reorganisation following motor learning are also evaluated. Secondly, a large body of evidence from both animal and human observations is reviewed that confirms that M1 representations can also be altered as a result of changes in availability of effectors or following sensory deprivation. The mechanisms underlying such a plasticity of cortical maps following peripheral lesions are increasingly well understood. Thirdly, we discuss data showing that a corticospinal system lesion can lead to a complete reorganisation of the area allocated to the hand representation in the primary motor cortex or to a reorganization of the whole network of motor areas responsible for voluntary movements. As a conclusion, therapeutical perspectives that result from a better understanding of those various mechanisms responsible for motor map plasticity are briefly discussed.

Further evidence that a shared efferent collicular pathway drives separate circuits for smooth eye movements and saccades

The aim of the present study was to find out whether smooth eye movements (SEMs) evoked by superior colliculus (SC) stimulation are, as suggested by Breznen et al. (1996), artefactual eye movements resulting from a non-physiological response of the saccadic generator. This question was reinvestigated in head-restrained cats. Long-lasting SC stimulation was found to evoke, in a comparable proportion, either a single saccade followed by an uninterrupted SEM or a staircase of two or three saccades interleaved with SEMs. These two different patterns of eye movements could be elicited at a near-threshold current and at low stimulation frequencies. In most cases, SEM direction clearly differed from that of the preceding saccade. This difference between SEM and saccade directions varied in a systematic way as a function of the initial saccade direction. As demonstrated by computer simulation, this observation can be explained if the neural circuit controlling SEMs reaches a saturation level earlier than the saccadic burst-generator. Our results in cats were reminiscent of those reported by Breznen et al. (1996) in the monkey only in some instances, when high frequency stimulation (400-600 Hz) was applied. Indeed, in the case of near-threshold stimulation-elicited staircase saccades, increasing the stimulation frequency led to a progressive disappearance of the smaller subsequent saccades that were substituted by uninterrupted SEM-like movements. Altogether, the present results confirm the view that SEMs are genuine eye movements. These results rule out the hypothesis that SEMs result from a saturation of the saccadic generator and strengthen the hypothesis that SEMs and saccades are distinct movements. We suggest that the same collicular efferent cells carry out the motor command to saccadic and SEM circuits and that the position error originating from the SC may be distributed amongst separate downstream motor systems.

Comparison of direct and indirect measurements of the central motor conduction time in the monkey

OBJECTIVE

The goal of the present study was to compare the indirect estimate of the central motor conduction time (CMCT) with direct measurement of the corticospinal conduction time between the motor cortex and cervical enlargement in macaque monkeys.

METHODS

Responses to transcranial magnetic stimulation of the motor cortex were recorded from intrinsic hand muscles in adult macaque monkeys. The CMCT was calculated by subtracting the peripheral conduction time, measured with the F-wave method, from the latency of the motor evoked potentials (MEPs). In two monkeys, the actual conduction time between the motor cortex and cervical enlargement was measured directly by different invasive techniques.

RESULTS

We found that the indirect calculation of CMCT overestimates the corticospinal conduction time to a significant extent.

CONCLUSIONS

One possible source of error is an underestimate of the MEP peripheral conduction time. A collision test confirmed this hypothesis and showed that only a marginal proportion of the motoneurones that respond to a weak corticospinal input also participate in the F-wave. A more accurate estimate of the CMCT could be obtained by using the longest F-wave latency, rather than the shortest, to calculate the peripheral conduction time.

A quantitative analysis of the correlations between eye movements and neural activity in the pretectum

The study of the saccadic system has focused mainly on neurons active before the beginning of saccades, in order to determine their contribution in movement planning and execution. However, most oculomotor structures contain also neurons whose activity starts only after the onset of saccades, the maximum of their activity sometimes occurring near saccade end. Their characteristics are still largely unknown. We investigated pretectal neurons with saccade-related activity in the alert cat during eye movements towards a moving target. They emitted a high-frequency burst of action potentials after the onset of saccades, irrespective of their direction, and will be referred to as "pretectal saccade-related neurons". The delay between saccade onset and cell activity varied from 17 to 66 ms on average. We found that burst parameters were correlated with the parameters of saccades; the peak eye velocity was correlated with the peak of the spike density function, the saccade amplitude with the number of spikes in the burst, and burst duration increased with saccade duration. The activity of six pretectal saccade-related neurons was studied during smooth pursuit at different velocities. A correlation was found between smooth pursuit velocity and mean firing rate. A minority of these neurons (2/6) were also visually responsive. Their visual activity was proportional to the difference between eye and target velocity during smooth pursuit (retinal slip). These results indicate that the activity of pretectal saccade-related neurons is correlated with the characteristics of eye movements. This finding is in agreement with the known anatomical projections from premotor regions of the saccadic system to the pretectum.

Chromosomal assignments of mammalian genes with an acute inflammation-regulated expression in liver

A set of acute inflammation-regulated genes expressed in liver has been assigned to rat, mouse, and human chromosomes by detecting species-specific PCR amplicons in rat(x)mouse or mouse(x)hamster somatic cell hybrids or radiation hybrids or by in silico matches of corresponding rat cDNAs to various libraries of previously assigned rat, mouse, or human genes or expressed-sequence tags. This allowed us to assign 24, 22, and 21 inflammation-regulated genes to rat, mouse, and human chromosomes, respectively. From these assignments as well as those previously determined for a larger set of genes with an acute inflammation-regulated transcription in liver, we further investigated whether such genes are clustered onto given chromosomes. A cluster was found on rat Chromosome (Chr) 6q with a conserved synteny on mouse Chr 12 and human Chr 14q13-q32, and another cluster previously reported on human Chr 1q has been extended with five further genes. Our data suggest that during an acute inflammation, a higher-order regulation may control some liver-expressed genes that share a given chromosome area.

Investigation into non-monosynaptic corticospinal excitation of macaque upper limb single motor units

There has been considerable recent debate as to relative importance, in the primate, of propriospinal transmission of corticospinal excitation to upper limb motoneurons. Previous studies in the anesthetized macaque monkey suggested that, compared with the cat, the transmission of such excitation via a system of C3-C4 propriospinal neurons may be relatively weak. However, it is possible that in the anesthetized preparation, propriospinal transmission of cortical inputs to motoneurons may be depressed. To address this issue, the current study investigated the responses of single motor units (SMUs) to corticospinal inputs in either awake (n = 1) or lightly sedated (n = 3) macaque monkeys. Recordings in the awake state were made during performance of a precision grip task. The responses of spontaneously discharging SMUs to electrical stimulation of the pyramidal tract (PT) via chronically implanted electrodes were examined for evidence of non-monosynaptic, presumed propriospinal, effects. Single PT stimuli (up to 250 microA; duration, 0.2 ms, 2 Hz) were delivered during steady discharge of the SMU (10-30 imp/s). SMUs were recorded from muscles acting on the thumb (adductor pollicis and abductor pollicis brevis, n = 18), wrist (extensor carpi radialis, n = 29) and elbow (biceps, n = 9). In all SMUs, the poststimulus time histograms to PT stimulation consisted of a single peak at a fixed latency and with a brief duration [0.74 +/- 0.25 (SD) ms, n = 56], consistent with the responses being mediated by monosynaptic action of cortico-motoneuronal (CM) impulses. Later peaks, indicating non-monosynaptic action, were not present even when the probability of the initial peak response was low and when there was no evidence for suppression of ongoing SMU activity following this peak (n = 20 SMUs). Even when repetitive (double-pulse) PT stimuli were used to facilitate transmission through oligosynaptic linkages, no later peaks were observed (16 SMUs). In some thumb muscle SMUs (n = 8), responses to PT stimulation were compared with those evoked by transcranial magnetic stimulation, using a figure-eight coil held over the motor cortex. Responses varied according the orientation of the coil: in the latero-medial position, single peak responses similar to those from the PT were obtained; their latencies confirmed direct excitation of CM cells, and there were no later peaks. In the posterio-anterior orientation, responses had longer latencies and consisted of two to three subpeaks. At least under the conditions that we have tested, the results provide no positive evidence for transmission of cortical excitation to upper limb motoneurons by non-monosynaptic pathways in the macaque monkey.

Neck muscles in the rhesus monkey. II. Electromyographic patterns of activation underlying postures and movements

Electromyographic (EMG) activity was recorded in < or = 12 neck muscles in four alert monkeys whose heads were unrestrained to describe the spatial and temporal patterns of neck muscle activation accompanying a large range of head postures and movements. Some head postures and movements were elicited by training animals to generate gaze shifts to visual targets. Other spontaneous head movements were made during orienting, tracking, feeding, expressive, and head-shaking behaviors. These latter movements exhibited a wider range of kinematic patterns. Stable postures and small head movements of only a few degrees were associated with activation of a small number of muscles in a reproducible synergy. Additional muscles were recruited for more eccentric postures and larger movements. For head movements during trained gaze shifts, movement amplitude, velocity, and acceleration were correlated linearly and agonist muscles were recruited without antagonist muscles. Complex sequences of reciprocal bursts in agonist and antagonist muscles were observed during very brisk movements. Turning movements of similar amplitudes that began from different initial head positions were associated with systematic variations in the activities of different muscles and in the relative timings of these activities. Unique recruitment synergies were observed during feeding and head-shaking behaviors. Our results emphasize that the recruitment of a given muscle was generally ordered and consistent but that strategies for coordination among various neck muscles were often complex and appeared to depend on the specifics of musculoskeletal architecture, posture, and movement kinematics that differ substantially among species.

Event-related TMS over the right posterior parietal cortex induces ipsilateral visuo-spatial interference

The right posterior parietal cortex (PPC) is implicated in visuo-spatial processing, as illustrated by patients with visuo-spatial neglect, but the precise time-course of its contribution is still an open question. In the present study we assessed whether single-pulse transcranial magnetic stimulation (TMS) can interfere with the performance of normal subjects in a standard visuo-spatial task. Participants had to perform a landmark task while TMS was applied over the right PPC, the homologue region in the left hemisphere or the right primary motor cortex. Stimulation was time-locked to the stimulus presentation with a stimulus onset asynchrony (SOA) varying between 50 and 200 ms. Our results indicate that TMS interfered mainly with the visuo-spatial task when applied over the right PPC at an early stage (50 ms post-stimulus). The interference effect of single-pulse TMS in the present visuo-spatial processing is revealed by a processing cost for ipsilateral targets. These results are in agreement with neuropsychological and brain imaging studies showing a right hemispheric dominance in visuo-spatial processing but add crucial information about the time-course of visuo-spatial processing within the right PPC.

Precise burst synchrony in the superior colliculus of the awake cat during moving stimulus presentation

This study aimed to characterize the synchrony that occurs between cell discharges in the superior colliculus of the awake cat. We trained cats to perform a visual fixation in the presence of a visual moving stimulus and then recorded 686 pairs of neighboring cells in the superior colliculus during task performance. A new method to assess the significance of precise discharge synchronization is described, which permits analysis of nonstationary data. Of 181 pairs with sufficient data for quantitative analysis, 125 showed a cross-correlation histogram (CCH) with features assessed as significant using this approach. CCHs frequently showed an isolated central peak (41 of 125) or a peak flanked by one or two troughs (68 of 125), and in a few cases an oscillatory pattern of approximately 65 Hz (16 of 125). This is in contrast to the oscillation frequency reported for the visual cortex and shows that oscillations in the superior colliculus probably arise from a cortex-independent mechanism. Our method also permits direct quantification of the correlation shift predictors, assessing precise time locking of spikes to the stimulus. Only 1 of 125 cross-correlation shift predictors had a significant central peak, meaning that most of the CCH features were not related to cell discharges time-locked to the stimulus presentation. Further investigation using a burst-jittering method showed that synchrony in the superior colliculus is attributable to precise synchronization of short bursts of spikes. Such synchrony could be related to the network dynamics and the common inhibitory feedback from local interneurons, which would act as temporal selectors of the cells with greatest or fastest response.

Quantitation of protein binding to the capillary wall in acidic, isoelectric buffers and means for minimizing the phenomenon

Notwithstanding the use of acidic, amphoteric, isoelectric buffers with isoelectric points (pI) in the pH 2-3 range, adsorption of proteins to the naked silica wall can be non-negligible. Two such buffers have been tested: iminodiacetic acid (IDA; pI 2.23, apparent pH 3.2 in 7 M urea) and aspartic acid (pI 2.77, apparent pH 3.7 in 7 M urea). Three potential quenchers of such interactions have been tested: hydroxyethylcellulose (HEC; number average molecular mass, Mr 27,000), TEPA (tetraethylenepentamine) and a novel, quatemarized piperazine [N(methyl-N-omega-iodobutyl)-N'-methylpiperazine] (Q-Pip), either alone or in binary and ternary mixtures. Human alpha- and beta-globin chains have been used as test proteins in capillary electrophoresis separations. It has been found that mixtures of these compounds are the worst possible remedy. E.g., a ternary mixture comprising 0.5% HEC, 0.5 mM TEPA and 1 mM Q-Pip still leaves behind 4.5% adsorbed protein onto the silica surface in runs in IDA buffer and 7 M urea (pH 3.2). Conversely, 0.5 mM TEPA or 1 mM Q-Pip, when used alone, minimize adsorption down to only 1.8% and 0.5%, respectively. When the same globin chain separations are performed in Asp and 7 M urea (pH 3.7), the situation is much worse: 44% protein is adsorbed in a ternary mixture of 0.5% HEC, 1 mM Q-Pip and 0.5 mM TEPA. However, when used alone, 0.5 mM TEPA and 1 mM Q-Pip reduce globin adsorption to levels of 8% and 5%, respectively. TEPA and Q-Pip are found to be in all cases the best quenchers of protein interaction to naked fused-silica; in addition they exhibit the unique property of smoothing the base-line and giving reproducible runs. The best method for desorbing bound protein was found to be an electrophoretic step consisting in driving sodium dodecylsulphate micelles from the cathodic reservoir.

Fetuin-B, a second member of the fetuin family in mammals

A set of orthologous plasma proteins found in human, sheep, pig, cow and rodents, now collectively designated fetuin-A, constitutes the fetuin family. Fetuin-A has been identified as a major protein during fetal life and is also involved in important functions such as inhibition of the insulin receptor tyrosine kinase activity, protease inhibitory activities and development-associated regulation of calcium metabolism and osteogenesis. Furthermore, fetuin-A is a key partner in the recovery phase of an acute inflammatory response. We now describe a second protein of the fetuin family, called fetuin-B, which is found at least in human and rodents. On grounds of domain homology, overall conservation of cysteine residues and chromosomal assignments of the corresponding genes in these species, fetuin-B is unambiguously a paralogue of fetuin-A. Yet, fetuin-A and fetuin-B exhibit significant differences at the amino acid sequence level, notably including variations with respect to the archetypal fetuin-specific signature. Differences and similarities in terms of gene regulation were also observed. Indeed, studies performed during development in rat and mouse showed for the first time high expression of a member of the fetuin family in adulthood, as shown with the fetuin-B mRNA in rat. However, like its fetuin-A counterpart, the fetuin-B mRNA level is down-regulated during the acute phase of experimentally induced inflammation in rat.