PROMOTION OF IN VITRO GROWTH OF HUMAN MEDULLOBLASTOMA CELLS BY EXOGENEOUS IL－6

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The SAG2 antigen ofToxoplasma gondii and the 31-kDa surface antigen ofSarcocystis muris share similar sequence features

In the search for similar cysteine distribution patterns among surface antigens of members of the phylum of Apicomplexa, we found a resemblance between TgSAG2, a 22-kDa surface antigen ofToxoplasma gondii, and the C-terminal half of a 31-kDa surface antigen ofSarcocystis muris, SmSAG1. The overall degree of similarity is low, corresponding to 28% of identity in the 146 amino acids aligned. However, the conservative spacing between the cysteine residues suggest that this similarity might have functional implications. The described amino acid similarity provides a new clue to the molecular relationship between two closely related coccidian parasites.     

Electrical conductivity variation of native and denatured DNA in the solid state as a function of acidity and structure

D. c. electrical solid state conductivity of either native or heat-denatured calf thymus DNA sodium it has been studied as a function of the acidic state of the samples. Conductivity implies major ionic carriers and depends on the secondary structure of the DNA sample. Its variation is correlated to the ion exchange properties of DNA solid phase suspension in a solvent. Partial renaturation of heat denatured DNA samples, induced by salt addition, increases the DNA solid state d.c. conductivity.     

Adoptive transfer of immunity induced by semi-allogeneic hybrid cells,against a murine fibrosarcoma

Semi-allogeneic somatic hybrid cells derived from the fusion of a C57BL/6 fibrosarcoma (MCB6–1) and A9 cells (C3H origin) were used to immunize C57BL/6 mice against the parental tumor cells. These hybrid cells expressed H-2 histocompatibility antigens of both parental cells (H-2_b and H-2^k), and failed to produce tumors in normal C57BL/6 mice. A single i.p. injection of hybrid cells induced anti-tumor immunity which could be transferred to normal C57BL/6 recipient mice by immune spleen or peritoneal cells; the efficient cells were T cells, as this activity was completely abrogated by treatment with anti-Thy-1–2 antiserum and complement. Among immune splenic T cells, only the light-density T cells, obtained after fractionation on Percoll gradient, were effective in the transfer of immunity. Immunity induced by the hybrid cells was specific for MCB6-1 parental tumor cells. This immunity could be transferred during two brief periods, 7 to 12 days, and 40 to 50 days, after hybrid cell injection; there appeared to be an intermediate period, 12 to 40 days after immunization, during which no immunity could be transferred. These results suggest a suppressive mechanism implicated during hybrid cell immunization and interacting with the anti-tumor immune response.     

Epidemiology and prevention of cutaneous melanoma

Opinion statement Melanoma incidence has continued to increase in all white populations, and mortality from melanoma remains high in older men worldwide. In Australia, Europe, and the United States, a substantial number of thick melanomas in older men are of the nodular subtype, a subtype lacking asymmetry or color change. Educating the public and pro-fessionals about the significance of evolving pigmented lesions as emphasized in the revised ABCDE of pigmented lesions is relevant. Targeting screening efforts toward older men will be necessary to decrease worldwide melanoma mortality. Among preven-tion strategies, emphasizing multiple methods of sun protection in early childhood, adolescence, and adulthood is needed to decrease sunburn rates. Chemoprevention research in melanoma should become a research priority to complement ongoing prevention strategies.     

Antitrypanosomal compounds from the leaf essential oil of Strychnos spinosa

The composition of the essential oil obtained by hydrodistillation of the leaves of Strychnos spinosa (Loganiaceae) was analysed by GC-FID and GC-MS. Out of twenty-two compounds identified in the oil, the main constituents were palmitic acid (34.3%), linalool (16.0%), and (E)-phytol (6.7%). Since the leaves of this plant are used in African traditional medicine to treat African trypanosomiasis, we evaluated the in vitro activity of the essential oil as well as of 15 of its components on Trypanosoma brucei brucei bloodstream forms and on mammalian cells (J774 murine macrophages) to evaluate the selectivity of the antitrypanosomal effect. The essential oil was active on the parasites without a great selectivity [IC50 on T. b. brucei = 13.5 microg/mL with a selectivity index (SI) of 4.4]. (E)-Nerolidol, a minor component of the hydrodistillate, as well as linalool, were shown to have a more potent and selective effect on the trypanosomes [IC50 = 1.7 and 2.5 microg/mL (7.6 and 16.3 microM) with SI = 35.7 and > 40, respectively]. These two oxygenated terpenes have promising activity and it would be of interest to study their mechanism of action as well as their in vivo activity.     

A natural anatoxin, Amm VIII, induces neutralizing antibodies against the potent scorpion alpha-toxins

In this study, we have used Amm VIII, a natural anatoxin from the scorpion Androctonus mauretanicus mauretanicus, to elicit specific polyclonal antibodies in rabbit. Using liquid-phase radioimmunoassay, we have studied its selectivity and its neutralizing activity both in vitro and in vivo for the most lethal scorpion alpha-toxins described, in particular the alpha-toxin of reference AaH II. We have shown that the anti-Amm VIII serum prevents the association of 125I-AaH II with its receptor and is able to remove 125I-AaH II already bound to its site (the half-life of the complex 125I-AaH II-receptor site was 12 min in the absence of anti-Amm VIII serum but decreased to only 2 min in the presence of anti-Amm VIII serum). In vivo, the serum also has a protective effect in mice: 42 LD50 of AaH II by millilitre are neutralized, measured by subcutaneous injection.     

Regular Extra Curricular Sports Practice Does Not Prevent Moderate Or Severe Variations in Self-Esteem Or Trait Anxiety in Early Adolescents

Physical activity is often presented as an effective tool to improve self-esteem and/or to reduce anxiety. The aim of this study was to measure the influence of a regular extra curricular sports practice on self-esteem and anxiety. We conducted a prospective cohort study, which has included all of the pupils entering the first year of secondary school (sixth grade) in the Vosges Department (east France) during the school year 2001-2002 and followed during three years. Data were collected every six months by self-reported questionnaires. 1791 pupils were present at each of the six data collection sessions and completed all the questionnaires, representing 10,746 documents: 835 boys (46.6 %) and 956 girls (53.4 %), in November 2001, the average age was 11.1 ± 0.5 years (mean ± standard deviation). 722 pupils (40.3 %) reported that they had practiced an extra-school physical activity in a sporting association from November 2001 to May 2004 (ECS group), whereas, 195 (10.9 %) pupils had not practiced any extra-school physical activity at all (NECS group). The average global scores of self-esteem (Rosenberg’s Scale) and trait anxiety (Spielberger’s Scale) of the ECS pupils were, respectively, higher and lower than those of the NECS group. However, the incidence density (number of new cases during a given period / total person-time of observation) of moderate or severe decrease of self-esteem (less than “mean - one standard deviation ”or less than “mean - two standard deviations”) was not significantly different between the two groups, a finding that was also evident also in the case of trait anxiety. Finally, among ECS pupils, the incidence density of severe decrease of self-esteem was lower at the girls’. Practitioners and physical education teachers, as well as parents, should be encouraged to seek out ways to involve pupils in extra-school physical activities.

Key Points

• A regular extra-curricular sports practice is associated to better levels of self-esteem and trait anxiety among young adolescent.
• This activity seems to protect girls from severe variations of self-esteem.
• Boys do not seem to be protected from moderate or severe variations, neither of self-esteem, nor of trait anxiety, by a regular extracurricular sport practice.

key words: Adolescents, self-esteem, trait anxiety, extra-curricular sport practice     

Er:YAG laser cavity preparation and composite resin bonding with a single-component adhesive system: relationship between shear bond strength and microleakage

BACKGROUND AND OBJECTIVES: The purpose of this study was to assess the performances of a single-component adhesive system when an Er:YAG laser was used to prepare cavities. STUDY DESIGN/MATERIALS AND METHODS: Shear bond strength tests were performed on composite rods bonded with a single-component adhesive system to dentin surfaces prepared using either bur+acid, Er:YAG laser (fluence = 44 J/cm2), or Er:YAG laser+acid. Class V cavities were prepared differently according to the molar surface: buccal surfaces were prepared using a diamond bur, and lingual surfaces using the Er:YAG laser. In group 1, cavity walls were not acid treated after Er:YAG laser preparation. In group 2, only the enamel walls were acid treated. In group 3, all the enamel and dentin walls were acid treated. Microleakage was assessed using a methylene blue dye penetration method. RESULTS: Bond strength values did not differ significantly between the three groups (P = 0.162). Better marginal adaptation was obtained between the composite resin and cavity walls when Er:YAG laser preparation was followed by a total acid etching (P = 0.008). CONCLUSIONS: Our results supported the use of single-component adhesive systems in cavities prepared using Er:YAG laser. The step of acid etching must be maintained for the whole cavity walls in regard of the microleakage values.