A clinical and neurophysiological motor signature of Unverricht-Lundborg disease

OBJECTIVES

Unverricht-Lundborg disease (ULD) is the most common form of progressive myoclonus epilepsy. Cerebellar dysfunction may appear over time, contributing along with myoclonus to motor disability. The purpose of the present work was to clarify the motor and neurophysiological characteristics of ULD patients.

METHODS

Nine patients with genetically proven ULD were evaluated clinically (medical history collected from patient charts, the Scale for the Assessment and Rating of Ataxia and Unified Myoclonus Rating Scale). Neurophysiological investigations included EEG, surface polymyography, long-loop C-reflexes, somatosensory evoked potentials, EEG jerk-locked back-averaging (JLBA) and oculomotor recordings. All patients underwent brain MRI. Non-parametric Mann-Whitney tests were used to compare ULD patients' oculomotor parameters with those of a matched group of healthy volunteers (HV).

RESULTS

Myoclonus was activated by action but was virtually absent at rest and poorly induced by stimuli. Positive myoclonus was multifocal, often rhythmic and of brief duration, with top-down pyramidal temporospatial propagation. Cortical neurophysiology revealed a transient wave preceding myoclonus on EEG JLBA (n=8), enlarged somatosensory evoked potentials (n=7) and positive long-loop C-reflexes at rest (n=5). Compared with HV, ULD patients demonstrated decreased saccadic gain, increased gain dispersion and a higher frequency of hypermetric saccades associated with decreased peak velocity.

CONCLUSION

A homogeneous motor pattern was delineated that may represent a ULD clinical and neurophysiological signature. Clinical and neurophysiological findings confirmed the pure cortical origin of the permanent myoclonus. Also, oculomotor findings shed new light on ULD pathophysiology by evidencing combined midbrain and cerebellar dysfunction.

Impact of prenatal and postnatal exposure to the pesticide chlorpyrifos on the contraction of rat ileal muscle strips: involvement of an inducible nitric oxide synthase-dependent pathway

BACKGROUND

Prenatal/postnatal exposure to insecticides has been linked to developmental disorders in adulthood. Chlorpyrifos (CPF) is a widely used organophosphorus acetylcholinesterase (AChE)-inhibiting insecticide. The present study established whether prenatal and postnatal exposure to CPF is associated with intestinal motor dysfunction in adult rats.

METHODS

Three groups of pregnant rats were exposed to either CPF (1 or 5 mg/kg/day; the CPF1 and CPF5 groups) or vehicle (the control group) by gavage from gestational day 1 until weaning. At weaning, the pups were separated from their dams and individually gavaged (with the same dose) until postnatal day 60. We then measured in vivo intestinal transit and the in vitro contractile responses of ileal smooth muscle strips to electrical field stimulation. Expression of inducible nitric oxide synthase (iNOS) in the ileum was determined using qRT-PCR and immunoblots. Morphometry and AChE assays were also performed.

KEY RESULTS

At adulthood, the mean body mass was lower in the CPF1 and CPF5 groups than in controls. CPF5 exposure was associated with weaker in vitro contraction of ileal muscle strips, which was reversed by adding the NOS inhibitor (L-NAME). There was no significant intergroup difference in the mean in vivo transit time. Exposure to CPF was associated with greater iNOS expression, lower AChE activity and reduced circular and longitudinal smooth muscle thickness.

CONCLUSIONS & INFERENCES

Prenatal and postnatal exposure to CPF in the rat is associated with weaker contraction of ileal longitudinal smooth muscle via a nitrergic mechanism with increased iNOS expression.

Voedselallergie: een kwelling voor mens en dier

Voedselallergie is een veel voorkomend probleem, zowel bij huisdieren als bij de mens. Zo wordt in de diergeneeskunde vaak voedselallergie vastgesteld bij de hond. Verschillende allergenen, zoals vlees, eieren en melk, worden aangeduid als boosdoener bij de hond en soms wordt er kruisreactiviteit gezien tussen verschillende allergenen. Bij de mens zijn vooral pinda’s, noten en koemelk bekend als veelvoorkomende antigenen. De symptomen variëren zowel bij de hond als bij de mens van huidklachten tot gastro-intestinale symptomen. De diagnosestelling van voedselallergie bij de hond gebeurt het beste door middel van een testdieet, bestaande uit twee fasen: de eliminatie- en provocatiefase. Andere testen, zoals de intradermale huidtest, serologie, de basofieldegranulatietest en gastroscopische voedselovergevoeligheidstest zijn ook beschikbaar. Echter, deze testen geven vaak weinig betrouwbare resultaten. De behandeling van voedselallergie berust in de eerste plaats op de eliminatie van het allergeen in de voeding. Dit kan eventueel worden aangevuld met medicatie, zoals corticosteroïden en antihistaminica.

Control of YAP/TAZ Activity by Metabolic and Nutrient-Sensing Pathways

Metabolism is a fundamental cellular function that can be reprogrammed by signaling pathways and oncogenes to meet cellular requirements. An emerging paradigm is that signaling and transcriptional networks can be in turn regulated by metabolism, allowing cells to coordinate their metabolism and behavior in an integrated manner. The activity of the YAP/TAZ transcriptional coactivators, downstream transducers of the Hippo cascade and powerful pro-oncogenic factors, was recently found to be regulated by metabolic pathways, such as aerobic glycolysis and mevalonate synthesis, and by the nutrient-sensing LKB1-AMPK and TSC-mTOR pathways. We discuss here current data linking YAP/TAZ to metabolism and suggest how this coupling might coordinate nutrient availability with genetic programs that sustain tissue growth, neoplastic cell proliferation, and tumor malignancy.

Lateralizing value of semiology in medial temporal lobe epilepsy

OBJECTIVES

Analysing the clinical characteristics of seizures constitutes a fundamental aspect of the presurgical evaluation of patients with medial temporal lobe epilepsy and unilateral hippocampal sclerosis (MTLE-HS), the most frequent form of focal epilepsy accessible to surgery. We sought to retrospectively determine whether objective manifestations could have a reliable lateralizing value in a large population of MTLE-HS patients and if their presence could help to identify those patients who would be seizure free after surgery.

MATERIAL AND METHODS

We analysed the frequency and predictive lateralizing value of objective ictal and postictal signs in 391 patients with MTLE-HS (183 left/208 right). Data were derived from chart review and not from blinded videoEEG analysis. Correlation between the presence of reliable lateralizing signs and postoperative outcome was performed in a subgroup of 302 patients who underwent surgery.

RESULTS

Contralateral dystonic posturing was the most frequent and reliable lateralizing sign that correctly lateralized the focus in 96% of patients. Unilateral head/eye deviation was noted in 42% of the patients and predicted unilateral focus in 67%. Ipsilateral postictal nose wiping, contralateral clonus and hypokinesia correctly lateralized the focus in 75%, 81%, respectively, and 100 of patients but were less frequently depicted. Postictal aphasia was a strong lateralizing sign for left MLE-HS. The presence of reliable lateralizing signs was not a predictor of seizure freedom.

CONCLUSION

Seizure semiology is a simple tool that may permit reliable lateralization of the seizure focus in MTLE-HS. The presence of reliable lateralizing signs is not associated with a better postoperative outcome.

Role of YAP/TAZ in cell-matrix adhesion-mediated signalling and mechanotransduction

Signalling from the extracellular matrix (ECM) is a fundamental cellular input that sustains proliferation, opposes cell death and regulates differentiation. Through integrins, cells perceive both the chemical composition and physical properties of the ECM. In particular, cell behaviour is profoundly influenced by the mechanical elasticity or stiffness of the ECM, which regulates the ability of cells to develop forces through their contractile actomyosin cytoskeleton and to mature focal adhesions. This mechanosensing ability affects fundamental cellular functions, such that alterations of ECM stiffness is nowadays considered not a simple consequence of pathology, but a causative input driving aberrant cell behaviours. We here discuss recent advances on how mechanical signals intersect nuclear transcription and in particular the activity of YAP/TAZ transcriptional coactivators, known downstream transducers of the Hippo pathway and important effectors of ECM mechanical cues.

Ocean warming and acidification modulate energy budget and gill ion regulatory mechanisms in Atlantic cod (Gadus morhua)

Ocean warming and acidification are threatening marine ecosystems. In marine animals, acidification is thought to enhance ion regulatory costs and thereby baseline energy demand, while elevated temperature also increases baseline metabolic rate. Here we investigated standard metabolic rates (SMR) and plasma parameters of Atlantic cod (Gadus morhua) after 3–4 weeks of exposure to ambient and future PCO₂ levels (550, 1200 and 2200 µatm) and at two temperatures (10, 18 °C). In vivo branchial ion regulatory costs were studied in isolated, perfused gill preparations. Animals reared at 18 °C responded to increasing CO₂ by elevating SMR, in contrast to specimens at 10 °C. Isolated gills at 10 °C and elevated PCO₂ (≥1200 µatm) displayed increased soft tissue mass, in parallel to increased gill oxygen demand, indicating an increased fraction of gill in whole animal energy budget. Altered gill size was not found at 18 °C, where a shift in the use of ion regulation mechanisms occurred towards enhanced Na⁺/H⁺-exchange and HCO₃⁻ transport at high PCO₂ (2200 µatm), paralleled by higher Na⁺/K⁺-ATPase activities. This shift did not affect total gill energy consumption leaving whole animal energy budget unaffected. Higher Na⁺/K⁺-ATPase activities in the warmth might have compensated for enhanced branchial permeability and led to reduced plasma Na⁺ and/or Cl⁻ concentrations and slightly lowered osmolalities seen at 18 °C and 550 or 2200 µatm PCO₂ in vivo. Overall, the gill as a key ion regulation organ seems to be highly effective in supporting the resilience of cod to effects of ocean warming and acidification.

Aerobic glycolysis tunes YAP/TAZ transcriptional activity

Increased glucose metabolism and reprogramming toward aerobic glycolysis are a hallmark of cancer cells, meeting their metabolic needs for sustained cell proliferation. Metabolic reprogramming is usually considered as a downstream consequence of tumor development and oncogene activation; growing evidence indicates, however, that metabolism on its turn can support oncogenic signaling to foster tumor malignancy. Here, we explored how glucose metabolism regulates gene transcription and found an unexpected link with YAP/TAZ, key transcription factors regulating organ growth, tumor cell proliferation and aggressiveness. When cells actively incorporate glucose and route it through glycolysis, YAP/TAZ are fully active; when glucose metabolism is blocked, or glycolysis is reduced, YAP/TAZ transcriptional activity is decreased. Accordingly, glycolysis is required to sustain YAP/TAZ pro-tumorigenic functions, and YAP/TAZ are required for the full deployment of glucose growth-promoting activity. Mechanistically we found that phosphofructokinase (PFK1), the enzyme regulating the first committed step of glycolysis, binds the YAP/TAZ transcriptional cofactors TEADs and promotes their functional and biochemical cooperation with YAP/TAZ. Strikingly, this regulation is conserved in Drosophila, where phosphofructokinase is required for tissue overgrowth promoted by Yki, the fly homologue of YAP. Moreover, gene expression regulated by glucose metabolism in breast cancer cells is strongly associated in a large dataset of primary human mammary tumors with YAP/TAZ activation and with the progression toward more advanced and malignant stages. These findings suggest that aerobic glycolysis endows cancer cells with particular metabolic properties and at the same time sustains transcription factors with potent pro-tumorigenic activities such as YAP/TAZ.

Relationship between invasion success and colony breeding structure in a subterranean termite

Factors promoting the establishment and colonization success of introduced populations in new environments constitute an important issue in biological invasions. In this context, the respective role of pre-adaptation and evolutionary changes during the invasion process is a key question that requires particular attention. This study compared the colony breeding structure (i.e. number and relatedness among reproductives within colonies) in native and introduced populations of the subterranean pest termite, Reticulitermes flavipes. We generated and analysed a data set of both microsatellite and mtDNA loci on termite samples collected in three introduced populations, one in France and two in Chile, and in the putative source population of French and Chilean infestations that has recently been identified in New Orleans, LA. We also provided a synthesis combining our results with those of previous studies to obtain a global picture of the variation in breeding structure in this species. Whereas most native US populations are mainly composed of colonies headed by monogamous pairs of primary reproductives, all introduced populations exhibit a particular colony breeding structure that is characterized by hundreds of inbreeding reproductives (neotenics) and by a propensity of colonies to fuse, a pattern shared uniquely with the population of New Orleans. These characteristics are comparable to those of many invasive ants and are discussed to play an important role during the invasion process. Our finding that the New Orleans population exhibits the same breeding structure as its related introduced populations suggests that this native population is pre-adapted to invade new ranges.

The biology of YAP/TAZ: hippo signaling and beyond

The transcriptional regulators YAP and TAZ are the focus of intense interest given their remarkable biological properties in development, tissue homeostasis and cancer. YAP and TAZ activity is key for the growth of whole organs, for amplification of tissue-specific progenitor cells during tissue renewal and regeneration, and for cell proliferation. In tumors, YAP/TAZ can reprogram cancer cells into cancer stem cells and incite tumor initiation, progression and metastasis. As such, YAP/TAZ are appealing therapeutic targets in cancer and regenerative medicine. Just like the function of YAP/TAZ offers a molecular entry point into the mysteries of tissue biology, their regulation by upstream cues is equally captivating. YAP/TAZ are well known for being the effectors of the Hippo signaling cascade, and mouse mutants in Hippo pathway components display remarkable phenotypes of organ overgrowth, enhanced stem cell content and reduced cellular differentiation. YAP/TAZ are primary sensors of the cell's physical nature, as defined by cell structure, shape and polarity. YAP/TAZ activation also reflects the cell "social" behavior, including cell adhesion and the mechanical signals that the cell receives from tissue architecture and surrounding extracellular matrix (ECM). At the same time, YAP/TAZ entertain relationships with morphogenetic signals, such as Wnt growth factors, and are also regulated by Rho, GPCRs and mevalonate metabolism. YAP/TAZ thus appear at the centerpiece of a signaling nexus by which cells take control of their behavior according to their own shape, spatial location and growth factor context.

Inflammation and pancreatic cancer: molecular and functional interactions between S100A8, S100A9, NT-S100A8 and TGFβ1

BACKGROUND

In order to gain further insight on the crosstalk between pancreatic cancer (PDAC) and stromal cells, we investigated interactions occurring between TGFβ1 and the inflammatory proteins S100A8, S100A9 and NT-S100A8, a PDAC-associated S100A8 derived peptide, in cell signaling, intracellular calcium (Cai2+) and epithelial to mesenchymal transition (EMT). NF-κB, Akt and mTOR pathways, Cai2+ and EMT were studied in well (Capan1 and BxPC3) and poorly differentiated (Panc1 and MiaPaCa2) cell lines.

RESULTS

NT-S100A8, one of the low molecular weight N-terminal peptides from S100A8 to be released by PDAC-derived proteases, shared many effects on NF-κB, Akt and mTOR signaling with S100A8, but mainly with TGFβ1. The chief effects of S100A8, S100A9 and NT-S100A8 were to inhibit NF-κB and stimulate mTOR; the molecules inhibited Akt in Smad4-expressing, while stimulated Akt in Smad4 negative cells. By restoring Smad4 expression in BxPC3 and silencing it in MiaPaCa2, S100A8 and NT-S100A8 were shown to inhibit NF-κB and Akt in the presence of an intact TGFβ1 canonical signaling pathway. TGFβ1 counteracted S100A8, S100A9 and NT-S100A8 effects in Smad4 expressing, not in Smad4 negative cells, while it synergized with NT-S100A8 in altering Cai2+ and stimulating PDAC cell growth. The effects of TGFβ1 on both EMT (increased Twist and decreased N-Cadherin expression) and Cai2+ were antagonized by S100A9, which formed heterodimers with TGFβ1 (MALDI-TOF/MS and co-immuno-precipitation).

CONCLUSIONS

The effects of S100A8 and S100A9 on PDAC cell signaling appear to be cell-type and context dependent. NT-S100A8 mimics the effects of TGFβ1 on cell signaling, and the formation of complexes between TGFβ1 with S100A9 appears to be the molecular mechanism underlying the reciprocal antagonism of these molecules on cell signaling, Cai2+ and EMT.

Optomechanical interactions in two-dimensional Si and GaAs phoXonic cavities

We investigate theoretically the optomechanical interactions inside cavities created in two-dimensional infinite phoXonic crystals constituted by a square array of holes in silicon (Si) and gallium arsenide (GaAs) matrices. The cavity is simply obtained by removing one hole in the perfect crystal. Our calculations take into account two mechanisms that contribute to the optomechanical coupling, namely the bulk photoelastic effect and the deformations of the interfaces due to the acoustic strain. The coupling strength is estimated by two different methods, modulation of the photonic mode frequency during one period of the acoustic oscillations and calculation of the optomechanical coupling rate. We discuss the important roles of the symmetry and degeneracy of the modes to discriminate which ones are not able to interact efficiently. Calculations in Si and GaAs crystals at different optical wavelengths emphasize the dependence of the photoelastic contribution to the optomechanical interaction as a function of material and wavelength, especially owing to the significant variation of the photoelastic coefficients near the semiconductor band gap.