Antitumour activities of levans produced by Zymomonas mobilis strains

Levans produced by four Zymomonas mobilis strains showed antitumour activity against sarcoma 180 and Ehrlich carcinoma in Swiss albino mice. Levans from two strains (ZAP and CP4) had the highest effects. NMR analysis showed that the polymers were composed only of fructose units. The results suggested that the antineoplasic effect is associated to the polysaccharide molecular weight and that a particular molecular weight range may be responsible for this effect.     

Nonsteroidal anti-inflammatory drugs and the induction of apoptosis in colon cells: Evidence for PHS-dependent and PHS-independent mechanisms

NSAIDs are potent chemopreventive agents for colon cancer. Although their mechanism of action is unknown, it probably relates to their modulation of colon epithelial cell kinetics, i.e. apoptosis and/or cell proliferation. NSAIDs are pleiotropic in their biochemical activities; their best known effect is inhibition of prostaglandin H synthase (PHS), the enzyme catalyzing the biosynthesis of prostaglandins. Current data appear to lead to two conflicting conclusions. One body of data indicates that PHS is important in induction of apoptosis and colon carcinogenesis and that its inhibition by NSAIDs is required for induction of apoptosis and their overall chemopreventive effect. Another set of data indicates that NSAIDs may induce apoptosis and prevent colon cancer without inhibiting the activity of PHS. Both sides of this argument are presented and discussed. This apparent contradiction may be resolved if one accepts that both mechanisms are correct but that they act on different steps of this multistep process.     

Insulin resistance and its contribution to colon carcinogenesis

The insulin resistance-colon cancer hypothesis, stating that insulin resistance may be associated with the development of colorectal cancer, represents a significant advance in colon cancer, as it emphasizes the potential for this cancer to become a modifiable disease. The fact that the incidence of insulin resistance has been increasing in the United States and much of the rest of the Western world where colon cancer remains the second leading cause of cancer death makes the exploration of the interrelationship of these conditions a subject of high priority. Here, we review the salient features of insulin resistance, defined as impaired biological response to the action of insulin. Recent epidemiological studies, evaluating potential associations between colon cancer risk and diabetes mellitus, dietary intake and metabolic factors, and IGF levels in several clinical settings, provide strong support of the insulin resistance-colon cancer hypothesis (without establishing causality). Mechanistically, insulin resistance has been associated with hyperinsulinemia, increased levels of growth factors including IGF-1, and alterations in NF-kappaB and peroxisome proliferator-activated receptor signaling, which may promote colon cancer through their effects on colonocyte kinetics. It is a reasonable expectation that in the not too distant future, critical interventions to the already mapped molecular sequence of events, which link two apparently disparate entities, combined with lifestyle changes could abrogate the development of colon cancer.     

An overview of malaria transmission from the perspective of Amazon Anopheles vectors

In the Americas, areas with a high risk of malaria transmission are mainly located in the Amazon Forest, which extends across nine countries. One keystone step to understanding the Plasmodium life cycle in Anopheles species from the Amazon Region is to obtain experimentally infected mosquito vectors. Several attempts to colonise Ano- pheles species have been conducted, but with only short-lived success or no success at all. In this review, we review the literature on malaria transmission from the perspective of its Amazon vectors. Currently, it is possible to develop experimental Plasmodium vivax infection of the colonised and field-captured vectors in laboratories located close to Amazonian endemic areas. We are also reviewing studies related to the immune response to P. vivax infection of Anopheles aquasalis, a coastal mosquito species. Finally, we discuss the importance of the modulation of Plasmodium infection by the vector microbiota and also consider the anopheline genomes. The establishment of experimental mosquito infections with Plasmodium falciparum, Plasmodium yoelii and Plasmodium berghei parasites that could provide interesting models for studying malaria in the Amazonian scenario is important. Understanding the molecular mechanisms involved in the development of the parasites in New World vectors is crucial in order to better determine the interaction process and vectorial competence.     

Subtle proteome differences identified between post-dormant vegetative and floral peach buds

Proper development of deciduous tree species, including peach, is accomplished through an annual growth cycle. Freezing avoidance during winter is necessary for tree survival and is achieved by the enclosure of meristems in floral and vegetative buds. To elucidate the role of developmentally regulated protein networks in bud break, proteins of the two bud-types were extracted and analyzed by two-dimensional gel electrophoresis (2-DE). Of the 1107 protein spots that were picked, 475 were identified and annotated assembling the peach bud proteome reference map. The majority of these proteins are involved in stress-response, detoxification, defense, carbohydrate metabolism and energy production. The protein profiles of both bud-types bear high similarity, whereas only 11 proteins were differentially expressed. These proteins were mainly involved in carbon-nitrogen homeostasis/metabolism and certain developmental processes to sustain rapid growth of the newly emerging organs. Among these are enzymes that differentially regulate the levels of H(2)O(2) between floral and vegetative buds, potentially promoting sequential bud-break. Distinct Nucleoside Diphosphate Kinase (NDPK) variants in floral and vegetative buds were detected suggesting the potential role of NDPKs in H(2)O(2)-mediated signaling for post-dormant bud break. This study provides data towards a better understanding of dormancy release and bud break.     

Correlation between bacterial indicators and bacteriophages in sewage and sludge

The use of bacteriophages as potential indicators of faecal pollution has recently been studied. The correlation of the number of bacterial indicators and the presence of three groups of bacteriophages, namely somatic coliphages (SOMCPH), F-RNA-specific phages (FRNAPH) and phages of Bacteroides fragilis (BFRPH), in raw and treated wastewater and sludge is presented in this study. Raw and treated wastewater and sewage sludge samples from two wastewater treatment plants in Athens were collected on a monthly basis, over a 2-year period, and analysed for total coliforms, Escherichia coli, intestinal enterococci and the three groups of bacteriophages. A clear correlation between the number of bacterial indicators and the presence of bacteriophages was observed. SOMCPH may be used as additional indicators, because of their high densities and resistance to various treatment steps.     

Nitric-oxide-donating NSAIDs as agents for cancer prevention

Nitric-oxide-donating nonsteroidal anti-inflammatory drugs (NO-NSAIDs), which consist of an NSAID with an NO-donating moiety covalently attached to it, promise to contribute significantly towards the development of effective chemoprevention strategies against cancer. NO-NSAIDs inhibit the growth of cultured cancer cells 10-6000-fold more potently than their parent NSAIDs and prevent colon cancer in animal tumor models. Clinical data indicate that they are extremely safe. Mechanistically, NO-aspirin, the best-studied NO-NSAID, has pleiotropic effects on cell signaling (it inhibits Wnt signaling, induces nitric oxide synthase and NF-kappaB activation and induces cyclooxygenase-2 expression), and this mechanistic redundancy might be central to its mode of action against cancer. The apparent safety and superior efficacy of NO-NSAIDs makes them promising chemopreventive agents against cancer.