Caveolin expression changes in the neurovascular unit after juvenile traumatic brain injury: signs of blood-brain barrier healing?

Traumatic brain injury (TBI) is one of the major causes of death and disability in pediatrics, and results in a complex cascade of events including the disruption of the blood-brain barrier (BBB). A controlled-cortical impact on post-natal 17 day-old rats induced BBB disruption by IgG extravasation from 1 to 3 days after injury and returned to normal at day 7. In parallel, we characterized the expression of three caveolin isoforms, cav-1, cav-2 and cav-3. While cav-1 and cav-2 are expressed on endothelial cells, both cav-1 and cav-3 were found to be present on reactive astrocytes, in vivo and in vitro. Following TBI, cav-1 expression was increased in blood vessels at 1 and 7 days in the perilesional cortex. An increase of vascular cav-2 expression was observed 7 days after TBI. In contrast, astrocytic cav-3 expression decreased 3 and 7 days after TBI. Activation of eNOS (via its phosphorylation) was detected 1 day after TBI and phospho-eNOS was detected both in association with blood vessels and with astrocytes. The molecular changes involving caveolins occurring in endothelial cells following juvenile-TBI might participate, independently of eNOS activation, to a mechanism of BBB repair while, they might subserve other undefined roles in astrocytes.

The release of antidiuretic hormone is appropriate in response to hypovolemia and/or sodium administration in children with severe head injury: a trial of lactated Ringer's solution versus hypertonic saline.

We conducted an open, randomized, and prospective study to determine the effect of hypertonic saline on the secretion of antidiuretic hormone (ADH) and aldosterone in children with severe head injury (Glasgow coma scale <8). Thirty-one consecutive patients at a level III pediatric intensive care unit at a children's hospital received either lactated Ringer's solution (Ringer's group, n = 16) or hypertonic saline (Hypertonic Saline group, n = 15) over a 3-day period. Serum ADH levels were significantly larger in the Hypertonic Saline group as compared with the Ringer's group (P = 0.001; analysis of variance) and were correlated to sodium intake (Ringer's group: r = 0.39, R(2) = 0.15, P = 0.02; Hypertonic Saline group: r = 0.42, R(2) = 0.18, P = 0.02) and volume of fluids given IV (Ringer's group: r = 0.38, R(2) = 0.15, P = 0.02; Hypertonic Saline group: r = 0.32, R(2) = 0.1, P = not significant). Correlation of ADH to plasma osmolality was significant if plasma osmolality was >280 mOsm/kg (r = 0.5, R(2) = 0.25, P = 0.06), indicating an osmotic threshold for ADH release. Serum aldosterone levels were larger on the first day than during Days 2 and 3 in both groups and inversely correlated to serum sodium levels only in the Ringer's group (r = -0.55, R(2) = 0.3, P < 0.001). This group received a significantly larger fluid volume on Day 1 (P = 0.05, Mann-Whitney U-test) than did patients in the Hypertonic Saline group, indicating hypovolemia during the first day. Head-injured children have appropriate levels of ADH. They may be hypovolemic during the first day of treatment, especially if they receive lactated Ringer's solution. IMPLICATIONS: In head-injured patients, we recommend fluid restriction to avoid inappropriate secretion of antidiuretic hormone. In a prospective, randomized, and controlled study in 31 children, we were able to show that the antidiuretic hormone levels are appropriate in response to hypovolemia, sodium load, or both.

Necrotrophic fungi associated with epidermal microcracking caused by chilling injury in pickling cucumber fruit

The objective of this work was to visualize the association between microcracking and other epidermal chilling injury symptoms, and to identify rots in cucumber fruit (Cucumis sativus L.) by scanning electron microscopy (SEM). Depressed epidermal areas and surface cracking due to damages of subepidermal cells characterized the onset of pitting in cucumber fruit. The germination of conidia of Alternaria alternata, with some of them evident on the fractures in the cultivar Trópico, occurred after damaging on the epidermis. Before, the chilling injury symptoms became visible, Stemphylium herbarum conidia germinated, and mycelium penetrated through the hypodermis using the microcracks as pathway. In the cultivar Perichán 121 the fungus was identified as Botrytis cinerea.

Thyroid function in severely traumatized patients with or without head injury.

The pattern of thyroid function changes following severe trauma was assessed prospectively in 35 patients during the first 5 days after injury. Patients were divided into 2 groups to evaluate the effect of head injury: group I, patients with severe head injury; group II, patients with multiple injuries without head injury. The results demonstrate a low T3 and low T4 syndrome throughout the study, with decreases in both total and free levels of T3 and T4, normal or increased rT3 levels, and normal TSH levels. The presence of severe head injury was associated with lower levels of TSH and free T3. Mortality was 37%. Survival was associated with higher TSH and T3 levels, but not with higher T4 levels. TSH levels exceeding 1 mU/l on the first day were only observed in survivors. These findings show that a typical low T3 and low T4 syndrome is present after severe trauma in patients with multiple injury as well as with head injury. Primary hypothyroidism can be excluded, pituitary or hypothalamic hypothyroidism is likely in these patients.

UVB-Induced Skin Inflammation and Cutaneous Tissue Injury Is Dependent on the MHC Class I-Like Protein, CD1d.

CD1d is a major histocompatibility complex class 1-like molecule that regulates the function and development of natural killer T (NKT) cells. Previously, we identified a critical role for the CD1d-NKT cell arm of innate immunity in promoting the development of UVB-induced p53 mutations, immune suppression, and skin tumors. Sunburn, an acute inflammatory response to UVB-induced cutaneous tissue injury, represents a clinical marker for non-melanoma skin cancer (NMSC) risk. However, the innate immune mechanisms controlling sunburn development are not considered relevant in NMSC etiology, and remain poorly investigated. Here we found that CD1d knockout (CD1d(-/-)) mice resist UVB-induced cutaneous tissue injury and inflammation compared with wild-type (WT) mice. This resistance was coupled with a faster epithelial tissue healing response. In contrast, the skins of UVB-irradiated invariant NKT cell-knockout (Jα18(-/-)) and NKT cell-deficient (TCRα(-/-)) mice, which express CD1d but are deficient in CD1d-dependent NKT cells, exhibited as much cutaneous tissue injury and inflammation as WT mice. In the absence of NKT cells, CD1d-deficient keratinocytes, dendritic cells, and macrophages exhibited diminished basal and stress-induced levels of pro-inflammatory mediators. Thus, our findings identify an essential role for CD1d in promoting UVB-induced cutaneous tissue injury and inflammation. They also suggest sunburn and NMSC etiologies are immunologically linked.

ACID-SENSING ION CHANNELS: functional and molecular characterization in putative nociceptors, and modulation by nerve injury and serine protease

Résumé Les canaux ioniques ASICs (acid-sensing ion channels) appartiennent à la famille des canaux ENaC/Degenerin. Pour l'instant, quatre gènes (1 à 4) ont été clonés dont certains présentent des variants d'épissage. Leur activation par une acidification rapide du milieu extracellulaire génère un courant entrant transitoire essentiellement sodique accompagné pour certains types d'ASICs d'une phase soutenue. Les ASICs sont exprimés dans le système nerveux, central (SNC) et périphérique (SNP). On leur attribue un rôle dans l'apprentissage, la mémoire et l'ischémie cérébrale au niveau central ainsi que dans la nociception (douleur aiguë et inflammatoire) et la méchanotransduction au niveau périphérique. Toutefois, les données sont parfois contradictoires. Certaines études suggèrent qu'ils sont des senseurs primordiaux impliqués dans la détection de l'acidification et la douleur. D'autres études suggèrent plutôt qu'ils ont un rôle modulateur inhibiteur dans la douleur. De plus, le fait que leur activation génère majoritairement un courant transitoire alors que les fibres nerveuses impliquées dans la douleur répondent à un stimulus nocif avec une adaptation lente suggère que leurs propriétés doivent être modulés par des molécules endogènes. Dans une première partie de ma thèse, nous avons abordé la question de l'expression fonctionnelle des ASICs dans les neurones sensoriels primaires afférents du rat adulte pour clarifier le rôle des ASICs dans les neurones sensoriels. Nous avons caractérisé leurs propriétés biophysiques et pharmacologiques par la technique du patch-clamp en configuration « whole-cell ». Nous avons pu démontrer que près de 60% des neurones sensoriels de petit diamètre expriment des courants ASICs. Nous avons mis en évidence trois types de courant ASIC dans ces neurones. Les types 1 et 3 ont des propriétés compatibles avec un rôle de senseur du pH alors que le type 2 est majoritairement activé par des pH inférieurs à pH6. Le type 1 est médié par des homomers de la sous-unité ASIC1 a qui sont perméables aux Ca2+. Nous avons étudié leur co-expression avec des marqueurs des nocicepteurs ainsi que la possibilité d'induire une activité neuronale suite à une acidification qui soit dépendante des ASICs. Le but était d'associer un type de courant ASIC avec une fonction potentielle dans les neurones sensoriels. Une majorité des neurones exprimant les courants ASIC co-expriment des marqueurs des nocicepteurs. Toutefois, une plus grande proportion des neurones exprimant le type 1 n'est pas associée à la nociception par rapport aux types 2 et 3. Nous avons montré qu'il est possible d'induire des potentiels d'actions suite à une acidification. La probabilité d'induction est proportionnelle à la densité des courants ASIC et à l'acidité de la stimulation. Puis, nous avons utilisé cette classification comme un outil pour appréhender les potentielles modulations fonctionnelles des ASICs dans un model de neuropathie (spared nerve injury). Cette approche fut complétée par des expériences de «quantitative RT-PCR ». En situation de neuropathie, les courants ASIC sont dramatiquement changés au niveau de leur expression fonctionnelle et transcriptionnelle dans les neurones lésés ainsi que non-lésés. Dans une deuxième partie de ma thèse, suite au test de différentes substances sécrétées lors de l'inflammation et l'ischémie sur les propriétés des ASICs, nous avons caractérisé en détail la modulation des propriétés des courants ASICs notamment ASIC1 par les sérines protéases dans des systèmes d'expression recombinants ainsi que dans des neurones d'hippocampe. Nous avons montré que l'exposition aux sérine-protéases décale la dépendance au pH de l'activation ainsi que la « steady-state inactivation »des ASICs -1a et -1b vers des valeurs plus acidiques. Ainsi, l'exposition aux serine protéases conduit à une diminution du courant quand l'acidification a lieu à partir d'un pH7.4 et conduit à une augmentation du courant quand l'acidification alleu à partir d'un pH7. Nous avons aussi montré que cette régulation a lieu des les neurones d'hippocampe. Nos résultats dans les neurones sensoriels suggèrent que certains courants ASICs sont impliqués dans la transduction de l'acidification et de la douleur ainsi que dans une des phases du processus conduisant à la neuropathie. Une partie des courants de type 1 perméables au Ca 2+ peuvent être impliqués dans la neurosécrétion. La modulation par les sérines protéases pourrait expliquer qu'en situation d'acidose les canaux ASICs soient toujours activables. Résumé grand publique Les neurones sont les principales cellules du système nerveux. Le système nerveux est formé par le système nerveux central - principalement le cerveau, le cervelet et la moelle épinière - et le système nerveux périphérique -principalement les nerfs et les neurones sensoriels. Grâce à leur nombreux "bras" (les neurites), les neurones sont connectés entre eux, formant un véritable réseau de communication qui s'étend dans tout le corps. L'information se propage sous forme d'un phénomène électrique, l'influx nerveux (ou potentiels d'actions). A la base des phénomènes électriques dans les neurones il y a ce que l'on appelle les canaux ioniques. Un canal ionique est une sorte de tunnel qui traverse l'enveloppe qui entoure les cellules (la membrane) et par lequel passent les ions. La plupart de ces canaux sont normalement fermés et nécessitent d'être activés pour s'ouvrire et générer un influx nerveux. Les canaux ASICs sont activés par l'acidification et sont exprimés dans tout le système nerveux. Cette acidification a lieu notamment lors d'une attaque cérébrale (ischémie cérébrale) ou lors de l'inflammation. Les expériences sur les animaux ont montré que les canaux ASICs avaient entre autre un rôle dans la mort des neurones lors d'une attaque cérébrale et dans la douleur inflammatoire. Lors de ma thèse je me suis intéressé au rôle des ASICs dans la douleur et à l'influence des substances produites pendant l'inflammation sur leur activation par l'acidification. J'ai ainsi pu montrer chez le rat que la majorité des neurones sensoriels impliqués dans la douleur ont des canaux ASICs et que l'activation de ces canaux induit des potentiels d'action. Nous avons opéré des rats pour qu'ils présentent les symptômes d'une maladie chronique appelée neuropathie. La neuropathie se caractérise par une plus grande sensibilité à la douleur. Les rats neuropathiques présentent des changements de leurs canaux ASICs suggérant que ces canaux ont une peut-être un rôle dans la genèse ou les symptômes de cette maladie. J'ai aussi montré in vitro qu'un type d'enryme produit lors de l'inflammation et l'ischémie change les propriétés des ASICs. Ces résultats confirment un rôle des ASICs dans la douleur suggérant notamment un rôle jusque là encore non étudié dans la douleur neuropathique. De plus, ces résultats mettent en évidence une régulation des ASICs qui pourrait être importante si elle se confirmait in vivo de part les différents rôles des ASICs. Abstract Acid-sensing ion channels (ASICs) are members of the ENaC/Degenerin superfamily of ion channels. Their activation by a rapid extracellular acidification generates a transient and for some ASIC types also a sustained current mainly mediated by Na+. ASICs are expressed in the central (CNS) and in the peripheral (PNS) nervous system. In the CNS, ASICs have a putative role in learning, memory and in neuronal death after cerebral ischemia. In the PNS, ASICs have a putative role in nociception (acute and inflammatory pain) and in mechanotransduction. However, studies on ASIC function are somewhat controversial. Some studies suggest a crucial role of ASICs in transduction of acidification and in pain whereas other studies suggest rather a modulatory inhibitory role of ASICs in pain. Moreover, the basic property of ASICs, that they are activated only transiently is irreconcilable with the well-known property of nociception that the firing of nociceptive fibers demonstrated very little adaptation. Endogenous molecules may exist that can modulate ASIC properties. In a first part of my thesis, we addressed the question of the functional expression of ASICs in adult rat dorsal root ganglion (DRG) neurons. Our goal was to elucidate ASIC roles in DRG neurons. We characterized biophysical and pharmacological properties of ASIC currents using the patch-clamp technique in the whole-cell configuration. We observed that around 60% of small-diameter sensory neurons express ASICs currents. We described in these neurons three ASIC current types. Types 1 and 3 have properties compatible with a role of pH-sensor whereas type 2 is mainly activated by pH lower than pH6. Type 1 is mediated by ASIC1a homomultimers which are permeable to Ca 2+. We studied ASIC co-expression with nociceptor markers. The goal was to associate an ASIC current type with a potential function in sensory neurons. Most neurons expressing ASIC currents co-expressed nociceptor markers. However, a higher proportion of the neurons expressing type 1 was not associated with nociception compared to type 2 and -3. We completed this approach with current-clamp measurements of acidification-induced action potentials (APs). We showed that activation of ASICs in small-diameter neurons can induce APs. The probability of AP induction is positively correlated with the ASIC current density and the acidity of stimulation. Then, we used this classification as a tool to characterize the potential functional modulation of ASICs in the spared nerve injury model of neuropathy. This approach was completed by quantitative RT-PCR experiments. ASICs current expression was dramatically changed at the functional and transcriptional level in injured and non-injured small-diameter DRG neurons. In a second part of my thesis, following an initial screening of the effect of various substances secreted during inflammation and ischemia on ASIC current properties, we characterized in detail the modulation of ASICs, in particular of ASIC1 by serine proteases in a recombinant expression system as well as in hippocampal neurons. We showed that protease exposure shifts the pH dependence of ASIC1 activation and steady-state inactivation to more acidic pH. As a consequence, protease exposure leads to a decrease in the current response if ASIC1 is activated by a pH drop from pH 7.4. If, however, acidification occurs from a basal pH of 7, protease-exposed ASIC1a shows higher activity than untreated ASIC1a. We provided evidence that this bi-directional regulation of ASIC1a function also occurs in hippocampal neurons. Our results in DRG neurons suggest that some ASIC currents are involved in the transduction of peripheral acidification and pain. Furthermore, ASICs may participate to the processes leading to neuropathy. Some Ca 2+-permeable type 1 currents may be involved in neurosecretion. ASIC modulation by serine proteases may be physiologically relevant, allowing ASIC activation under sustained slightly acidic conditions.

Fractures du calcanéum: du traumatisme aux séquelles [Fractures of the calcaneus: the injury and its sequelae]

The calcaneus gives shape to the heel. Its special position places it in direct contact with the floor, upon which rests the weight of the body. It assures the transition between the vertical skeleton and horizontal surface of the foot, thus permitting ambulation. The calcaneus is subjected to high physical stress, yet at the same time its complex articulating surfaces permit fine adaptation to the ground. Fractures of the calcaneus result from a high energy injury, usually a fall from a height. The treatment of such fractures poses difficult problems. The functional sequelae of the injury may be severe, prolonged, and frequently results in a permanent disability. This is due not only to the type of fracture, but the orthopaedic management as well. Careful evaluation of the patient, fracture pattern, soft tissue condition, and treatment modalities is obligatory to achieve the optimal result.

Spiral CT aortography: an efficient technique for the diagnosis of traumatic aortic injury.

The objective of this study was to assess the efficiency of spiral CT (SCT) aortography for diagnosing acute aortic lesions in blunt thoracic trauma patients. Between October 1992 and June 1997, 487 SCT scans of the chest were performed on blunt thoracic trauma patients. To assess aortic injury, the following SCT criteria were considered: hemomediastinum, peri-aortic hematoma, irregular aspect of the aortic wall, aortic pseudodiverticulum, intimal flap and traumatic dissection. Aortic injury was diagnosed on 14 SCT examinations (2.9 %), five of the patients having had an additional digital aortography that confirmed the aortic trauma. Twelve subjects underwent surgical repair of the thoracic aorta, which in all but one case confirmed the aortic injury. Two patients died before surgery from severe brain lesions. The aortic blunt lesions were confirmed at autopsy. According to the follow-up of the other 473 patients, we are aware of no false-negative SCT examination. Our limited series shows a sensitivity of 100 % and specificity of 99.8 % of SCT aortography in the diagnosis of aortic injury. It is concluded that SCT aortagraphy is an accurate diagnostic method for the assessment of aortic injury in blunt thoracic trauma patients.

Cannabidiol protects against hepatic ischemia/reperfusion injury by attenuating inflammatory signaling and response, oxidative/nitrative stress, and cell death.

Ischemia/reperfusion (I/R) is a pivotal mechanism of liver damage after liver transplantation or hepatic surgery. We have investigated the effects of cannabidiol (CBD), the nonpsychotropic constituent of marijuana, in a mouse model of hepatic I/R injury. I/R triggered time-dependent increases/changes in markers of liver injury (serum transaminases), hepatic oxidative/nitrative stress (4-hydroxy-2-nonenal, nitrotyrosine content/staining, and gp91phox and inducible nitric oxide synthase mRNA), mitochondrial dysfunction (decreased complex I activity), inflammation (tumor necrosis factor α (TNF-α), cyclooxygenase 2, macrophage inflammatory protein-1α/2, intercellular adhesion molecule 1 mRNA levels; tissue neutrophil infiltration; nuclear factor κB (NF-κB) activation), stress signaling (p38MAPK and JNK), and cell death (DNA fragmentation, PARP activity, and TUNEL). CBD significantly reduced the extent of liver inflammation, oxidative/nitrative stress, and cell death and also attenuated the bacterial endotoxin-triggered NF-κB activation and TNF-α production in isolated Kupffer cells, likewise the adhesion molecule expression in primary human liver sinusoidal endothelial cells stimulated with TNF-α and attachment of human neutrophils to the activated endothelium. These protective effects were preserved in CB(2) knockout mice and were not prevented by CB(1/2) antagonists in vitro. Thus, CBD may represent a novel, protective strategy against I/R injury by attenuating key inflammatory pathways and oxidative/nitrative tissue injury, independent of classical CB(1/2) receptors.

Myocardial tolerance to ischemia-reperfusion injury, training intensity and cessation.

Training has been shown to induce cardioprotection. The mechanisms involved remain still poorly understood. Aims of the study were to examine the relevance of training intensity on myocardial protection against ischemia/reperfusion (I/R) injury, and to which extent the beneficial effects persist after training cessation in rats. Sprague-Dawley rats trained at either low (60% [Formula: see text]) or high (80% [Formula: see text]) intensity for 10 weeks. An additional group of highly trained rats was detrained for 4 weeks. Untrained rats served as controls. At the end of treatment, rats of all groups were split into two subgroups. In the former, rats underwent left anterior descending artery (LAD) ligature for 30 min, followed by 90-min reperfusion, with subsequent measurement of the infarct size. In the latter, biopsies were taken to measure heat-shock proteins (HSP) 70/72, vascular endothelial growth factor (VEGF) protein levels, and superoxide dismutase (SOD) activity. Training reduced infarct size proportionally to training intensity. With detraining, infarct size increased compared to highly trained rats, maintaining some cardioprotection with respect to controls. Cardioprotection was proportional to training intensity and related to HSP70/72 upregulation and Mn-SOD activity. The relationship with Mn-SOD was lost with detraining. VEGF protein expression was not affected by either training or detraining. Stress proteins and antioxidant defenses might be involved in the beneficial effects of long-term training as a function of training intensity, while HSP70 may be one of the factors accounting for the partial persistence of myocardial protection against I/R injury in detrained rats.

Alcohol and cannabis use as risk factors for injury--a case-crossover analysis in a Swiss hospital emergency department.

BACKGROUND: There is sufficient and consistent evidence that alcohol use is a causal risk factor for injury. For cannabis use, however, there is conflicting evidence; a detrimental dose-response effect of cannabis use on psychomotor and other relevant skills has been found in experimental laboratory studies, while a protective effect of cannabis use has also been found in epidemiological studies. METHODS: Implementation of a case-crossover design study, with a representative sample of injured patients (N = 486; 332 men; 154 women) from the Emergency Department (ED) of the Lausanne University Hospital, which received treatment for different categories of injuries of varying aetiology. RESULTS: Alcohol use in the six hours prior to injury was associated with a relative risk of 3.00 (C.I.: 1.78, 5.04) compared with no alcohol use, a dose-response relationship also was found. Cannabis use was inversely related to risk of injury (RR: 0.33; C.I.: 0.12, 0.92), also in a dose-response like manner. However, the sample size for people who had used cannabis was small. Simultaneous use of alcohol and cannabis did not show significantly elevated risk. CONCLUSION: The most surprising result of our study was the inverse relationship between cannabis use and injury. Possible explanations and underlying mechanisms, such as use in safer environments or more compensatory behavior among cannabis users, were discussed.