The DNA damage response is developmentally regulated in the African trypanosome.

Genomes are affected by a wide range of damage, which has resulted in the evolution of a number of widely conserved DNA repair pathways. Most of these repair reactions have been described in the African trypanosome Trypanosoma brucei, which is a genetically tractable eukaryotic microbe and important human and animal parasite, but little work has considered how the DNA damage response operates throughout the T. brucei life cycle. Using quantitative PCR we have assessed damage induction and repair in both the nuclear and mitochondrial genomes of the parasite. We show differing kinetics of repair for three forms of DNA damage, and dramatic differences in repair between replicative life cycle forms found in the testse fly midgut and the mammal. We find that mammal-infective T. brucei cells repair oxidative and crosslink-induced DNA damage more efficiently than tsetse-infective cells and, moreover, very distinct patterns of induction and repair of DNA alkylating damage in the two life cycle forms. We also reveal robust repair of DNA lesions in the highly unusual T. brucei mitochondrial genome (the kinetoplast). By examining mutants we show that nuclear alkylation damage is repaired by the concerted action of two repair pathways, and that Rad51 acts in kinetoplast repair. Finally, we correlate repair with cell cycle arrest and cell growth, revealing that induced DNA damage has strikingly differing effects on the two life cycle stages, with distinct timing of alkylation-induced cell cycle arrest and higher levels of damage induced death in mammal-infective cells. Our data reveal that T. brucei regulates the DNA damage response during its life cycle, a capacity that may be shared by many microbial pathogens that exist in variant environments during growth and transmission.

Quantitative evaluation of intact peripheral nerve structures after utilization of CO2 laser, electrocautery, and scalpel.

OBJECTIVE: This study aimed to evaluate quantitatively the integrity of nerve structures near CO2 laser incisions. BACKGROUND DATA: There are some hypotheses that try to explain the analgesia reported after CO2 laser surgery. One of them is based upon the observation of the destruction of nerve endings after use of this technique. METHODS: A comparative study was carried out using 25 animals (Rattus norvegicus) divided into five groups of 5 animals each. Standard incisions were carried on the dorsum of the tongue of each animal using the cautery (group 2), scalpel (group 3), CW CO2 laser (group 4), and SPS CO2 (group 5); group I served as control. The animals were killed immediately after the experiment, and specimens were taken and routinely processed to wax. Three-micrometer sections were cut and stained using S-100 protein antibody. The stained sections were analyzed under light microscopy using a calibrated graticule, and the number of intact nerves was counted in five standard areas around the incision. RESULTS: The results of this study showed that there were no statistically significant differences in the numbers of intact peripheral nerve structures in both laser groups and other groups. No statistically significant difference was found between nonoperated and scalpel groups. The number of intact peripheral structures in cautery wounds was significantly smaller than in non-operated and scalpel wounds. CONCLUSIONS: Therefore, it is unlikely that immediate destruction of peripheral nerve structures is the cause of post-operative analgesia following CO2 laser surgery.

Fatores maternos e fetais associados ao nascimento de prematuros com 1.000 gramas ou menos. / Maternal and fetal factores associated with the birth of premature of 1,000g or less

O perfil das gestantes de baixo nivel socio-economico em nossa pesquisa, que deram a luz prematuros com 1.000 g ou menos, tem as seguintes caracteristicas: - nao eram primigestas; - tinham idade media de 26,6 anos; - nao fizeram seguimento pre-natal; - apresentaram alguma complicacao gestacional.Nao foi verificada nenhuma influencia da cor, estado civil e ocorrencia de abortos anteriores. O parto foi normal em 83,82% dos casos e a apresentacao cefalica em 77,94% das vezes. O bebe nasceu gravemente deprimido em 67,69% dos casos e com idade gestacional entre 22 e 30 semanas em 58,82% das vezes, sendo que 50,9% foram adequados para a idade gestacional e os demais; pequenos para a idade gestacional.As mortes neonatais ocorreram em 75% dos casos ate o 10o. dia de vida. Nos achados de necropsia predominaram: imaturidade cerebral e renal, atelectasia pulmonar congestao visceral generalizada e as sufusoes hemorragicas multiplas. Houve baixas-incidencias de persistencia do canal arterial e de membrana hialina