Role of tissue-derived plasminogen activator (t-PA) in an excitotoxic mouse model of neonatal white matter lesions

White matter (WM) lesions in preterm newborns may lead to cerebral palsy. To study WM lesions in a mouse model, we used intrapallial stereotactic injections of ibotenic acid, an N-methyl-D-aspartate receptor agonist. Previous studies support a contribution of tissue-type plasminogen activator (t-PA) to the brain lesions seen in various adult excitotoxic models. Therefore, we studied both 5-day-old (P5) wild-type mice and t-PA knock-out (t-PA-/-) mice. The ibotenic acid doses required to induce WM cysts were lower in the wild-type mice (EC50 < 0.01 microg/animal) than in the t-PA-/- mice (EC50 = 2.5 microg/animal) (p < 0.01), indicating the existence of t-PA-dependent and t-PA-independent mechanisms. Dose-dependent prolonged cyst growth occurred in the wild-type mice only. Early microglial activation and astrogliosis were similar in the wild-type and t-PA-/- mice. In adult mice (P45), demyelination occurred at the injection site in both groups but the astroglial scar was denser in the wild-type than in the t-PA-/- mice. These data support involvement of t-PA at several stages of WM lesion formation. Inactivation of t-PA might confer protection by prolonged hemostasis. The role of t-PA in cyst expansion suggests a new approach to the development of neuroprotective strategies in infants with developing WM lesions.     

In vivo imaging of cardiovascular endothelin receptors using the novel radiolabelled antagonist [18F]-SB209670 and positron emission tomography (microPET)

The aim of this study was to develop an F-labelled analogue of SB209670 with subnanomolar affinity for the endothelin receptor and to test whether it would have the required pharmacokinetic properties to permit binding and imaging of endothelin receptors in rat heart in vivo using small animal positron emission tomography (PET) imaging. [18F]-SB209670 could be produced in a total radiochemical yield of 14.9 +/- 3.8% in 162 +/- 7 minutes (n = 6). The radiochemical purity of the isolated radioligand was 99% and the specific activity was 100-150 GBq/micromol. In vitro characterization using ligand-binding assays demonstrated that [18F]-SB209670 bound with a single subnanomolar affinity to human heart tissue (n = 3) with a KD = 0.67 +/- 0.14 nM and a Bmax = 168.3 +/- 29.3 fmol/mg protein. The binding was time-dependent with a half-time (t(1/2)) for association of 3.8 minutes and an association rate constant (kobs) of 0.182 +/- 0.032/min. In vivo distribution in the rat was studied using microPET. Dynamic imaging revealed a fast clearance of [F]-SB209670 from the circulation by the liver, indicative of a high degree of metabolism. However, visualization of uptake in the rat heart was achievable and dynamic PET data together with the in vitro results suggest that [F]-SB209670 binds rapidly and primarily to endothelin-A receptors in the heart.     

A chemically inert drug can stimulate T cells in vitro by their T cell receptor in non-sensitised individuals

Drugs can interact with T cell receptors (TCR) after binding to peptide-MHC structures. This binding may involve the formation of a stable, covalent bond between a chemically reactive drug and MHC or the peptide embedded within. Alternatively, if the drug is chemically inert, the binding may be non-covalent and readily reversible. Both types of drug presentation account for a substantial number of adverse side effects to drugs. Presently no tests are available to predict the ability of chemically inert drugs to stimulate an immune response. Here we present data on the successful induction of a primary T cell immune response in vitro against a chemically inert drug using blood from healthy individuals, previously not exposed to the drug. Blood lymphocytes were stimulated by the chemically inert drug sulfamethoxazole and the protein-reactive drug-metabolite sulfamethoxazole-nitroso in the presence of IL-2. 9/10 individuals reacted in response to sulfamethoxazole-nitroso, but only three reacted to the chemically inert compound sulfamethoxazole. Drug reactive T cells could be detected after 14-35 days of cell culture by drug-specific proliferation or cytotoxicity, which was MHC-restricted. These cells were CD4, CD8 positive or CD4/CD8 double positive and T cell clones generated secreted Th0 type cytokines. Drug interaction lead to down-regulation of specific TCR. These data confirm the ability of chemically inert drugs to stimulate certain T cells by their TCR and may provide the opportunity to screen new drugs for their ability to interact with TCRs.     

Cannabis use, sport practice and other leisure activities at the end of adolescence

PURPOSE: To study the relationship between cannabis use, sports practice and other leisure activities during adolescence, as a test for the sociological theory of deviant opportunities. METHODS: A sample of 12,512 French adolescents aged 18 responded to an anonymous self-reported questionnaire in March 2001. Three logistic models (for occasional, recent and regular cannabis use) were estimated for girls and boys separately. RESULTS: Outings and other peer-oriented activities were strongly correlated with cannabis use but this relationship depended on which levels of use were considered. Occasional use was more common among respondents who participated in many different outdoor activities. Regular use was associated with a more selective lifestyle, focusing on music-oriented outings and time spent at a friend's home in the evening. CONCLUSIONS: Our results provided empirical support for the theory of deviant opportunities. Changing patterns of lifestyle associated with transition from initiation to higher levels of use may reveal a shift from opportunities of cannabis use provided by a wide range of activities to specific activities chosen for their convenience to cannabis use. Further research will need to investigate how drug use is shaped by lifestyle, and conversely, how drug use reshapes lifestyle.     

Culture-proven herpetic keratitis after penetrating keratoplasty in patients with no previous history of herpes disease

OBJECTIVE: To report three cases of herpetic infection in recipients of organ-cultured donor corneas among 586 consecutive corneal transplantation procedures. METHODS: Three patients with no history of symptomatic herpes infection underwent corneal transplantation for keratoconus (2 patients) and Fuchs dystrophy (1 patient). Two patients developed keratouveitis and primary graft failure. The third patient developed dendritic keratitis in the graft. Culture of corneal scrapings and the patient's bandage contact lens were positive for herpes simplex virus type 1 (HSV-1). Donor and recipient sera were tested for HSV serology by EIA. Recipient corneal buttons were studied by means of transmission electron microscopy and immunohistochemistry. The three HSV-1 strains were genotyped by sequencing part of a variable antigenic domain of glycoprotein B (gB). RESULTS: None of the donor corneas showed endothelial cell necrosis after organ culture. All keratoplasties performed with the three mate donor corneas had an uncomplicated course. All three donor sera were positive for HSV. Preoperative recipient sera were positive for HSV. Analysis of the recipient corneal buttons showed no evidence of herpetic infection. Sequence analysis revealed three different gB genotypes. CONCLUSION: Ascertaining that a postoperative herpetic infection in a corneal transplant originates from the donor tissue is still difficult. Although some features of the reported cases suggest donor-to-host transmission of herpes simplex virus, the recipients could have been the source of the virus.     

Decreased alcohol self-administration and increased alcohol sensitivity and withdrawal in CB1 receptor knockout mice

Recent advances in the understanding of the neurobiological basis of alcohol dependence suggest that the endocannabinoid system may play a key role in the reinforcing effects of ethanol. In the present study, disruption of CB1 receptors in mice generated on a CD1 background decreased both ethanol consumption and preference. This decreased ethanol self-administration was associated with increased sensitivity to the acute intoxicating effects of ethanol. Mutant mice were more sensitive to the hypothermic and sedative/hypnotic effects of acute ethanol administration (1.5-4.0 g/kg), although plasma ethanol concentrations did not differ from those of controls. Moreover, wild-type mice exhibited normal locomotor activation caused by 1.0-2.5 g/kg injection of ethanol, whereas mutant mice displayed sedation in response to the injection of the same ethanol doses. The severity of alcohol withdrawal-induced convulsions was also increased in CB1(-/-) mice. Our results suggest that CB1 receptors participate in the regulation of ethanol drinking and demonstrate that their disruption lead to increased ethanol sensitivity and withdrawal severity.     

Degree of concurrency among experts in data collection and diagnostic hypothesis generation during clinical encounters

BACKGROUND: Given that there are variations in clinicians' reasoning, methods to elaborate scoring checklists for standardised patient-based assessment need to be valid. The use of data elicited by experts solving problems independently has been advocated as a method of setting performance standards. AIMS: To determine the degree of concurrence and common characteristics among items independently elicited by doctors during patient encounters and to assess the number of experts needed to derive reliable performance standards. METHODS: Six experienced internists worked-up the same 7 chief complaints with standardised patients (SPs). A stimulated recall of the recorded encounter was then performed. The degree of concurrence of the collected history and physical examination information and the generated diagnostic hypotheses was computed. Reliability was derived from generalisability analyses. RESULTS: By case, experts elicited a mean of 114 information items (SD = 15) and generated 30 diagnostic hypotheses (SD = 6). A high concurrence (80-100%) was observed for a mean of 22 information items (20%; SD = 6) and 7 diagnostic hypotheses (24%; SD = 2). More than a third of the 153 highly concurrent information items were clarification questions. At least 3 doctors were needed to obtain a reliability of 0.80 or higher when deriving the scoring checklists. CONCLUSION: The limited concurrency in data elicited by clinicians during a patient encounter supports the use of high-fidelity methods to develop performance checklists used in SP-based assessment. It also suggests that relying only on information collected to assess clinical competence may not be sufficient. Additional criteria, such as structure and style of work-up, should be further explored.     

The effects of decanted sediments on embryogenesis in oysters (Crassostrea gigas)

Sediments act as sinks for contaminants of natural and anthropogenic origin, constituting a risk to the living organisms. In this study, sediments were collected from three sites on the coast of southwest France. The objective of this research was to determine the effects of sediments on embryonic development of bivalves and to identify precisely when the contaminants affect the embryos and induce them to develop in an abnormal way. The toxicity of decanted sediments and overlying waters were assessed using the oyster embryo bioassay. The physical characteristics and contaminant levels in the sediments were measured, including polycyclic aromatic hydrocarbon (PAH) and metal concentrations. Despite contaminant concentrations for PAH and metals only exceeding the effects range-low levels, all decanted sediments tested induced deleterious effects on the embryonic development of oysters, while no significant abnormalities were observed for overlying waters. The study results suggest that abnormal larvae mainly are caused by direct contact with contaminated sediments.     

Cutaneous malignant melanoma and neurofibromatosis type 1

Neurofibromatosis 1 (NF1) is a genetically transmitted disease occurring approximately once in 3000 live births and resulting from mutations of the NF1 gene that encodes a protein named neurofibromin, a negative regulator of the ras-dependent pathway. An excess of neoplasia especially tumours of neuroectodermal origin is classically observed. The occurrence of malignant melanoma in patients with NF1 has already been described in scattered clinical reports but little is known as to the characteristics of melanoma arising in NF1 patients. A multicentric retrospective study was conducted on a panel of French referring centres for a period of 13 years to identify patients with both melanoma and NF1. Patients with mucosal or ocular melanoma were excluded. The diagnosis of malignant melanoma was based on specific histology whereas NF1 was identified according to the criteria proposed by the NIH Consensus Conference. All patient fulfilling criteria for both melanoma and NF1 were investigated using a common procedure recording clinical and histological data along with prognostic factors for the two diseases. Eleven patients were identified with both diseases. The clinical pattern of NF1 was quite similar to the classical form of the disease, but some unusual features were present as regards to the melanoma: a sex-ratio of 10 women for one man and an average age lower than expected (median age=33 years) for melanoma occurrence. Among prognostic factors, median thickness was high compared to large series of melanoma in the literature (3.20 versus 1.5 mm). Another neoplasia occurred in three patients. An increase in melanoma incidence in patients with NF1 remains hypothetical but our small series of malignant melanoma arising in NF1 patients displays a large female preponderance, a higher thickness than expected and a frequent association with a second neoplasia. The peculiar female proneness for cancer whatever its localization and the risk of multiple neoplasias have already been reported in NF1 patients and could be true for malignant melanoma as well.