-(A new rapid and sensitive enzymatic method for extraction and quantification of starch in plant material). In this work we compare methods normally used for starch determination in plant materials. The comparison between chemical (McCready's method) and an enzymatic method proposed here showed that although McCready's method is appropriate for most plant materials, in certain cases where cell wall polysaccharides (pectins and hemicelluloses) are present, the results may be significantly altered. However, using the enzymatic method described here afforded accurate estimation of starch content in such tissues. The enzymatic method proposed in this work is an affordable option for precise determination of starch contents in several plant tissues. Key words: hydrolases, starch, storage carbohydrates RESUMO -(Novo método enzimático rápido e sensível de extração e dosagem de amido em materiais vegetais). Neste trabalho é feita uma comparação entre os métodos mais comumente utilizados para a dosagem de amido em materiais vegetais. A comparação entre um método químico (McCready) e o método enzimático proposto neste trabalho mostra que, embora o primeiro seja apropriado para a maioria dos materiais vegetais, nos casos em que polissacarídeos de parede celular (pectinas e hemiceluloses) estão presentes, os resultados podem ser bastante alterados. Entretanto, ao usar o método enzimático apresentado, foi possível obter estimativas acuradas dos conteúdos de amido de diversos tecidos vegetais. O método proposto neste trabalho é uma opção viável para determinação do conteúdo de amido em diversos tecidos de plantas. Palavras-chave: amido, carboidratos de reserva, hidrolases IntroduçãoO amido é um dos principais compostos de reserva em plantas. Ao longo da evolução tem sido usado não somente como reserva para a própria planta, mas também como uma das mais importantes fontes de energia para os níveis subseqüentes da cadeia alimentar nos ecossistemas (Zeeman et al. 2004). Por esta razão, vários organismos adquiriram a capacidade de produzir enzimas que degradam o amido com subseqüente liberação de glucose e uso no metabolismo energético.O amido é composto por unidades de glucose, organizadas em dois homopolissacarídeos, a amilose e a amilopectina. A amilose praticamente não apresenta ramificações, sendo que as unidades de glucose são conectadas por ligações glicosídicas do tipo α (1,4) e a porcentagem de ramificações α (1,6) é menor do que 1% (Ball et al. 1998). A amilopectina, uma das maiores biomoléculas conhecidas, é altamente ramificada e possui cadeias de resíduos de glucose ligados entre si por ligações glicosídicas do tipo α (1,4) com aproximadamente 5% de ramificações α (1,6) (Myers et al. 2000). Dependendo da origem, o amido possui diferentes proporções de amilose e de amilopectina. Normalmente as proporções variam em torno de 1:3 e 1:4, mas há extremos encontrados em mutantes, como nos mutantes "waxy" de milho, cujo amido não possui amilose (Nelson & Pan 1995).Em células vegetais, o amido é armazenado na forma ...

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Oxaliplatin is a platinum-derived antitumor drug that is active against cisplatin-resistant tumors and has lower overall toxicity than does cisplatin. DNA adduct formation is believed to mediate the cytotoxic activity of both compounds; however, the adducts may also be responsible for mutagenic and secondary tumorigenic activities. In this study, we have compared the mutagenicity of oxaliplatin and cisplatin in the Hprt gene of CHO-K1 cells. Both drugs produced dose-related increases in mutant frequency. For 1-hr treatments, oxaliplatin was less mutagenic than cisplatin at equimolar doses, while similar mutant frequencies were induced at equitoxic doses. Sequencing of mutant Hprt genes indicated that the mutation spectra of both oxaliplatin and cisplatin were significantly different from the spontaneous mutation spectrum (P = 0.014 and P = 0.008, respectively). A significant difference was also observed between the spectra of oxaliplatin- and cisplatin-induced mutations (P = 0.033). Although G:C-->T:A transversion was the most common mutation produced by both compounds, oxaliplatin produced higher frequencies of A:T-->T:A transversion than did cisplatin, most commonly at nucleotide 307, and higher frequencies of small deletions/insertions. Also, cisplatin induced tandem base-pair substitutions, mainly at positions 135/136, and a higher frequency of G:C-->A:T transition than did oxaliplatin. These results provide the first evidence that oxaliplatin is mutagenic and that the profiles of cisplatin- and oxaliplatin-induced mutations display not only similarities but also distinctive features relating to the type and sequence-context preference for mutation. Environ.

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Microdeletions in AZFa, AZFb and AZFc regions lead to different patterns of male infertility, from severe oligozoospermia to non-obstructive azoospermia. Intrachromosomal homologous recombination mechanisms were already identified in patients with simultaneous microdeletions in the AZFb and AZFc regions. Ten patients with atypical AZFb and AZFc deletion patterns were studied. The definition of those microdeletions and the fine characterization of the respective breakpoints were performed using sequence tagged sites/single nucleotide variants-PCR and DNA sequencing. Y-chromosome haplogroups were determined to establish a putative association with the patterns obtained. Seven deletion patterns were identified, P5/terminal (30%; 3/10), P5/P1 distal (20%; 2/10), IR4/distal-P2, IR2/proximal-P1, IR4/distal-P1, P4/terminal and complete AZFb/c deletion (10%; 1/10). Breakpoint sequence analysis suggests that only in one patient the P5/P1 distal deletion pattern was due to a homologous recombination mechanism. Sequence alignment of the other deletion patterns suggest that they have resulted from non-homologous recombination mechanisms.

Hybrid nanomaterials based on the covalent grafting of silylated naphthopyrans (NPTs) onto silica nanoparticles (SiO2 NPs) were successfully prepared and studied as new photochromic materials. They were prepared by a two-step protocol consisting of (i) NPTs (derivatives from 2H-naphtho[1,2-b]pyran (2H-NPT) and 3H-naphtho[2,1-b]pyran (3H-NPT)) silylation by a microwave-assisted reaction between hydroxyl-substituted NPTs and 3-(triethoxysilyl)propyl isocyanate, followed by (ii) covalent post-grafting onto SiO2 NPs. In order to study the role of the silylation step, the analogous non-silylated nanomaterials were also prepared by direct adsorption of NPTs. The characterization techniques confirmed the successful NPTs silylation and subsequent grafting to SiO2 NPs. All SiO2-based nanomaterials revealed photoswitching behavior, following a biexponential decay. The SiO2 NPs functionalized with silylated 3H-NPTs (SiO2@S3 and SiO2@S4) presented the most promising photochromic properties, showing fast coloration/decoloration kinetics (coloring in 1 min under UV irradiation and fading in only 2 min) and high values of total color difference (ΔE*ab = 30-50). Also, the 2H-NPTs-based SiO2 NPs (SiO2@S1 and SiO2@S2) presented fast coloration and good color contrasts (ΔE*ab = 54), but slower fading kinetic rates, taking more than 2 h to return to their initial color. In contrast, the SiO2 NPs functionalized with non-silylated NPTs (SiO2@1 and SiO2@3) showed weaker color contrasts (ΔE*ab = 6-10) and slower fading kinetics, proving that the NPT silylation step was crucial to enhance the photochromic behavior of SiO2 NPs based on NPTs. Furthermore, the silylated-based nanomaterials showed good photostability upon prolonged UV light exposure, keeping their photochromic performance unchanged for at least 12 successive UV/dark cycles, anticipating interesting technological applications in several areas.

Peritoneal encapsulation (PE) is a rare congenital malformation, characterized by a thin accessory peritoneal membrane which covers all or part of the small bowel, forming an accessory peritoneal sac. Most cases are asymptomatic and diagnosed incidentally during surgery and/or autopsy. Clinical presentation with intestinal obstruction is extremely rare and we report a case. A 25-year-old male, referred to emergency department with diffuse abdominal pain, crampy, with 8 h evolution, associated with nausea, vomiting and constipation in the last 48 h. The abdominal examination revealed an asymmetric and fixed distension, with hard consistency on palpation of lower abdominal quadrants. The abdominal radiography reveals a small bowel distension and fluid levels. Submitted to laparoscopic surgery that recourse to conversion because there is a total peritoneal encapsulation of the small bowel. After opening the peritoneal sac, we find a rotation of mesentery, at its root, conditioning twisting of small bowel and consequently occlusion. Uneventful postoperative with discharged at the 6(th) day. The PE is a very rare congenital anomaly characterized by abnormal bowel back into the abdominal cavity in the early stages of development. Your knowledge becomes important because, although rare, it might be diagnosis in patients with intestinal obstruction, in the absence of other etiologic factors.