Biochemistry and molecular biology techniques for person characterization.

Using the traditional serological tests and the most novel techniques for DNA fingerprinting, forensic scientists scan different traits that vary from person to person and use the data to include or exclude suspects based on matching with the evidence obtained in a criminal case. Although the forensic application of these methods is well known, the procedures and techniques used to obtain these results are not so well studied. Here, we report a laboratory exercise aimed to familiarize the students in several of the methods and markers employed for people individualization. With this exercise, students have to characterize themselves and an unknown sample according to the following characteristics: ABO blood group, presence or absence of Y chromosome, and their polymorphism for a variable number of tandem repeats (VNTR). This exercise has been originally developed for students of the course "Techniques in Criminology" within the Bachelor of Criminology. Although the schedule and procedures have been addressed to students who are faced for their first time with a laboratory of molecular biology, the exercise can also be adapted to students in more specialized courses and studies.

Prevalence of tinea capitis and tinea pedis in Barcelona schoolchildren.

BACKGROUND: Although dermatophytoses can appear at any age, some types are particularly prevalent in children. There are no prior data on the prevalence of tinea capitis and tinea pedis in Barcelona, Spain. To identify the prevalence of tinea in school children in the area with the highest immigrant population in this city, a cross-sectional study was performed. A second objective was to identify the etiologic agent to study the possibility of the introduction of foreign dermatophyte species and to evaluate the possibility of encountering healthy hosts. METHODS: From October 2002 until June 2003, we evaluated 1305 schoolchildren, ages 3-15 years, belonging to 21 schools located in the inner city of Barcelona to determine the prevalence of tinea capitis and pedis in school children. Cultures of scalp and feet were done in each child. RESULTS: 36(2.8%) children had tinea pedis and 3 (0.23%) had tinea capitis. One child had tinea capitis and tinea pedis, caused by different species (t. capitis caused by Trichophyton mentagrophytes and tinea pedis caused by Trichophyton rubrum). Of the 39 positive cases for dermatophytes, the etiologic agent in 18 (46.1%) was T. mentagrophytes, 17 (43.5%) T. rubrum, 2 (5.5%) Epidermophyton floccosum and 2 (5.5%) Trichophyton tonsurans. Of these 39 cases of tinea, 15 (38.5%) were Spanish natives and 22 (56.4%) were immigrants. CONCLUSION: The prevalence of tinea capitis was lower that we had expected, and it was noted that there was a greater prevalence of tinea pedis among schoolchildren 13-15 years of age (64.10%), the great majority of them male. The number of cases of tinea was significantly greater in immigrants.