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A 3-year-old male was beaten by his stepfather, resulting in a lesion of the third portion of the duodenum that was treated with an occlusive suture of the pyloric mucosa for pyloric exclusion and a gastric-jejunal anastomosis with a double jejunostomy for alimentation with a good result, no serious complications, and relatively a short hospitalization. This procedure may be an alternative for other similar cases.

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The metal chelators 1,10-phenanthroline and 2,9-dimethyl-1,10-phenanthroline (neocuproine) showed distinct abilities to prevent hydroxyl radical formation from hydrogen peroxide and Cu+ or F2(2+) (Fenton reaction) as determined by electron spin resonance. o-Phenanthroline prevented both Fe- and Cu-mediated Fenton reactions whereas neocuproine only prevented the Cu-mediated Fenton reaction. Because only 1,10-phenanthroline but not neocuproine prevented DNA strand-break formation in hydrogen peroxide-treated mammalian fibroblasts it appears that the Fe-mediated, as compared to the Cu-mediated, intranuclear Fenton reaction is responsible for DNA damage.

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Chinese hamster cells (V79) resistant to high concentrations of Cd2+ in the medium were obtained by using the procedure of Beach & Palmiter [(1981) Proc. Natl. Acad. Sci. U.S.A. 78, 2110-2114], which in mouse led to amplification of metallothionein (MT) genes and to an enrichment in cellular MT. The Cd-resistant V79 clones isolated were significantly more resistant than parental cells to oxidative stress by extracellular H2O2 or a mixture of H2O2 and superoxide anion (O2-) generated by xanthine oxidase plus acetaldehyde. On a per-cell basis, there was no difference between the two cells in their total H2O2-decomposing or O2-(-)dismutating activity. The most likely explanation is that an enrichment in MT content in the Cd-resistant cells was responsible for this effect, because of the antioxidant properties already described for this protein.

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When Chinese hamster fibroblasts were exposed to hydrogen peroxide or to a system consisting of xanthine oxidase and hypoxanthine, which generates superoxide anion plus hydrogen peroxide, sister-chromatid exchanges (SCEs) were formed in a dose-dependent manner. When the iron-complexing agent o-phenanthroline was present in the medium, however, the production of these SCEs was completely inhibited. This fact indicates that the Fenton reaction: Fe2+ + H2O2----OH0 + OH- + Fe3+ is responsible for the production of SCEs. When O2- and H2O2 were generated inside the cell by incubation with menadione, the production of SCE was prevented by co-incubation with copper diisopropylsalicylate, a superoxide dismutase mimetic agent. The most likely role of O2- is as a reducing agent of Fe3+: O2- + Fe3+----Fe2+ + O2, so that the sum of this and the Fenton reaction, i.e., the iron-catalyzed Haber-Weiss reaction, provides an explanation for the active oxygen species-induced SCE: H2O2 + O2(-)----OH- + OH0 + O2. According to this view, the OH radical thus produced is the agent which ultimately causes SCE. These results are discussed in comparison with other mechanisms previously proposed for induction of SCE by active oxygen species.

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Active oxygen species are suspected as being a cause of the cellular damage that occurs at the site of inflammation. Phagocytic cells accumulate at these sites and produce superoxide ion, hydrogen peroxide and hydroxyl radical. The ultimate killing species, the cellular target and the mechanism whereby the lethal injury is produced are unknown. We exposed mouse fibroblasts to xanthine oxidase and acetaldehyde, a system which mimics the membrane of phagocytic cells in terms of production of oxygen species. We observed that the generation of these species produced DNA strand breaks and cellular death. The metal chelator o-phenanthroline completely abolished the former effect, and at the same time it effectively protected the cells from lethal injuries. Because complexing iron o-phenanthroline prevents the formation of hydroxyl radical by the Fendon reaction (Fe(II) + H2O2----Fe(III) + OH- + OH.), it is proposed that most of the cell death and DNA damage are brought about by OH radical, produced from other species by iron-mediated reactions.

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Pterygium inversum unguis (PIU) is a digital anomaly characterized by adherence of the subungueal tissue to the ventral surface of the distal nail plates. Universal medical literature in ten years reported 24 cases. The foresight that this anomaly could be more frequent, although unnoticed, led us to perform a survey through a systematic digital checking of all patients who were examined by us, in a 8 month period. In this period 2,000 clients were examined, 1,000 being of the female sex and 1,000 of the male sex. Eight cases of PIU of hands, with no familiar trait were diagnosed, 6 of them in females and 2 in males. From the cases in males, 1 was of the idiopathic congenital type and the other was of the secondary type (post-traumatic). From the cases identified in females, 5 were of the idiopathic type (4 acquired and 1 congenital) and 1 was of the secondary type (dermatomyositis). PIU was diagnosed in 8 of the 2,000 adult patients examined by us, reaching 0.4% in frequency. The final result was in accordance with our previous opinion that is not uncommon the incidence of the PIU allowing us to assemble in a short period of time a number of cases larger than any other survey found in medical literature.

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The rate of loss of reproductive capacity produced by hydrogen peroxide was shown to be 6-times faster for human fibroblasts than for Chinese hamster fibroblasts. Mouse fibroblasts exhibited an intermediate response. The explanation for that does not lie in the different capacities of these cells to destroy H2O2. The kinetics of repair of single-strand breaks although slightly different for the three cell lines also does not provide a full explanation for the different sensitivity. What was shown to correlate well with the killing effect was the yield of strand breaks produced by H2O2 in the DNA of cells from the three species. A similar H2O2 concentration produced 5-10-times more strand breaks in human DNA than in hamster DNA and 2-4-times more than in mouse DNA. This ratio holds for different cell lines from human and hamster and thus seems to be species-specific. Based on our previous findings we propose that this difference may lie in the amount of chromatin-bound iron and the level of superoxide ion in these cells.

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Phenanthroline, a strong iron chelator, prevents both the formation of DNA single-strand breaks and the killing of mouse cells produced by H2O2. These results, taken together with our previous findings, indicate that the DNA damage is produced by hydroxyl radicals formed when H2O2 reacts with chromatin-bound Fe2+ and that this damage is responsible for the killing effect.

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Phenanthroline and bipyridine, strong chelators of iron, protect DNA from single-strand break formation by H2O2 in human fibroblasts. This fact strongly supports the concept that these DNA single-strand breaks are produced by hydroxyl radicals generated by a Fenton-like reaction between intracellular Fe2+ and H2O2: H2O2 + Fe2+----Fe3+ + OH- + OH: Corroborating this idea is the fact that thiourea, an effective OH radical scavenger, prevents the formation of DNA single-strand breaks by H2O2 in nuclei from human fibroblasts. The copper chelator diethyldithiocarbamate, a strong inhibitor of superoxide dismutase, greatly enhances the in vivo production of DNA single-strand breaks by H2O in fibroblasts. This supports the idea that Fe3+ is reduced to Fe2+ by superoxide ion: O divided by 2 + Fe3+----O2 + Fe2+; and therefore that the sum of this reaction and the Fenton reaction, namely the so-called Haber-Weiss reaction, H2O2 + O divided by 2----O2 + OH- + OH; represents the mode whereby OH radical is produced from H2O2 in the cell. EDTA completely protects DNA from single-strand break formation in nuclei. The chelator therefore removes iron from the chromatin, and although the Fe-EDTA complex formed is capable of reacting with H2O2, the OH radical generated under these conditions is not close enough to hit DNA. Therefore iron complexed to chromatin functions as catalyst for the Haber-Weiss reaction in vivo, similarly to the role played by Fe-chelates in vitro.

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A model is proposed to describe the rate of DNA synthesis observed under certain conditions in UV irradiated mammalian cells. It is assumed that shortly after irradiation the rate of DNA synthesis drops mainly as a consequence of the drop in the rate of movement of the replication fork. This in turn, is due to a pause at the dimer for a limited length of time. Later on, a recovery in the rate of DNA synthesis occurs, and it is proposed that one of the parameters contributing to that is an increase in the number of active replicons. This simple model enables one to predict variations in the rate of DNA synthesis as a function both of UV dose and of time after irradiation.

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Trachyonychia e termo que designa a opacificacao e enrugamento com aspereza de superficie das unhas, originados pela formacao de cerradas estriacoes longitudinais e tendo varias causas. Para firmar o diagnostico, e imprescindivel que varias unhas sejam simultaneamente atingidas. Como manifestacao, nao e mais especifica do que a onicolise. A alteracao ungueal conhecida como "distrofia das 20 unhas na infancia" e uma forma idiopatica de trachyonychia reversivel com o decorrer dos anos.O diagnostico diferencial deve ser feito com o liquen plano, a alopecia areata e a psoriase, entre outros. No caso de "distrofia das 20 unhas" que descrevemos, as manifestacoes da trachyonychia estavam presentes.A forma idiopatica da alteracao ungueal ficou constatada pelos exames realizados inclusive pela histopatologia

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Um caso de pili annulati do couro cabeludo e relatado. O pai da paciente tambem apresenta a anomalia. O estudo microscopico permitiu a confirmacao do diagnostico, bem como a diferenciacao com o pseudopili annulati

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Os autores propoem tecnica para hemostasia, em transplante de cabelo, empregando protese cilindrica introduzida nos orificios feitos pelo "punch". Esse procedimento alem de produzir a hemostasia dilata temporariamente os orificios das areas receptoras facilitando a colocacao dos enxertos

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Os autores reavaliam um caso de micetoma actinomicetico nocardiosico, 12 anos apos a cura clinica. Nao obstante a multiplicidade das lesoes existentes, com acometimento osseo extenso, enfatizam que foi obtida uma resposta rapida com o emprego da associacao corticosteroide-sulfamidico.A cura se mantem decorridos 12 anos.A reavaliacao clinica mostrou apenas lesoes cicatriciais. O estudo radiologico mostrou que no femur as alteracoes se mantinham, e ainda mais, que houve recuperacao completa das alteracoes radiologicas inicialmente observadas em fibula e tibia

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