Community analysis of arbuscular mycorrhizal fungi and bacteria in the maize mycorrhizosphere in a long-term fertilization trial.

FEMS Microbiol Ecol. 2008 Jun 9;

Authors: Toljander JF, Santos-González JC, Tehler A, Finlay RD

In this study, we investigated the impact of organic and mineral fertilizers on the community composition of arbuscular mycorrhizal (AM) fungi and bacteria in the mycorrhizosphere of maize in a field experiment established in 1956, in south-east Sweden. Roots and root-associated soil aggregates were sampled four times during the growing season in 2005, in control plots and in plots amended with calcium nitrate, ammonium sulphate, green manure, farmyard manure or sewage sludge. Fungi in roots were identified by cloning and sequencing, and bacteria in soil aggregates were analysed by terminal-restriction fragment length polymorphism, cloning and sequencing. The community composition of AM fungi and bacteria was significantly influenced by the different fertilizers. Changes in microbial community composition were mainly correlated with changes in pH induced by the fertilization regime. However, other factors, including phosphate and soil carbon content, also contributed significantly to these changes. Changes in bacterial community composition and a reduction in bacterial taxon richness throughout the growing season were also manifest. The results of this study highlight the importance and significant effects of the long-term application of different fertilizers on edaphic factors and specific groups of fungi and bacteria playing a key role in arable soils. PMID: 18547325 [PubMed - as supplied by publisher]

Effect of drying and rewetting on bacterial growth rates in soil.

FEMS Microbiol Ecol. 2008 Jun 9;

Authors: Iovieno P, Bååth E

The effect of soil moisture on bacterial growth was investigated, and the effects of rewetting were compared with glucose addition because both treatments increase substrate availability. Bacterial growth was estimated as thymidine and leucine incorporation, and was compared with respiration. Low growth rates were found in air-dried soil, increasing rapidly to high stable values in moist soils. Respiration and bacterial growth at different soil moisture contents were correlated. Rewetting air-dried soil resulted in a linear increase in bacterial growth with time, reaching the levels in moist soil (10 times higher) after about 7 h. Respiration rates increased within 1 h to a level >10 times higher than that in moist soil. After the initial flush, there was a gradual decrease in respiration rate, while bacterial growth increased to levels twice that of moist soil 24 h after rewetting, and decreased to levels similar to those in moist soil after 2 days. Adding glucose resulted in no positive effect on bacterial growth during the first 9 h, despite resulting in more than five times higher respiration. This indicated that the initial increase in bacterial growth after rewetting was not due to increased substrate availability. PMID: 18547324 [PubMed - as supplied by publisher]

Neonatal diabetes mellitus because of pancreatic agenesis with dysmorphic features and recurrent bacterial infections.

Pediatr Diabetes. 2008 Jun;9(3 Pt 1):240-4

Authors: Taha D, Bardise J, Hegab A, Bonnefond A, Marchand M, Drunat S, Vaxillaire M, Polak M

Pancreatic agenesis is a rare cause of neonatal diabetes mellitus (NDM). It can be associated with malformations of the heart, the biliary tract, and the cerebellum. We report an infant with NDM because of pancreatic agenesis, intra-uterine growth retardation, dysmorphic features, and recurrent bacterial infections. He was born to healthy consanguineous parents. With adequate replacement of insulin and pancreatic enzymes, his blood glucose levels were controlled and his weight slowly increased. However, he continued to develop recurrent serious bacterial infections and died at the age of 11 months with sepsis and respiratory failure. Analysis of the PTF1A and PDX1 genes, which have been associated with congenital agenesis of the pancreas, did not reveal any mutation. Genetic abnormalities of chromosome 6 associated with transient neonatal diabetes as well as mutations in the KCNJ11 and ABCC8 genes encoding the pancreatic potassium channel were also excluded as a cause of the NDM in this patient. The association of permanent neonatal diabetes because of pancreatic agenesis, dysmorphism, and non-specific immunodeficiency is previously undescribed and may represent a new possibly autosomal recessive syndrome. PMID: 18547237 [PubMed - in process]

Anticancer Therapeutics: Targeting Macromolecules and Nanocarriers to Hyaluronan or CD44, a Hyaluronan Receptor.

Mol Pharm. 2008 Jun 12;

Authors: Platt VM, Szoka FC

The complex system involved in the synthesis, degradation and binding of the high molecular weight glycosaminoglycan hyaluronic acid (hyaluronan or HA) provides a variety of structures that can be exploited for targeted cancer therapy. In many cancers of epithelial origin there is an upregulation of CD44, a receptor that binds HA. In other cancers, HA in the tumor matrix is overexpressed. Both CD44 on cancer cells and HA in the matrix have been targets for anticancer therapy. Even though CD44 is expressed in normal epithelial cells and HA is part of the matrix of normal tissues, selective targeting to cancer is possible. This is because macromolecular carriers predominantly extravasate into the tumor and not normal tissue; thus CD44-HA targeted carriers administered intravenously localize preferentially into tumors. Anti-CD44 antibodies have been used in patients to deliver radioisotopes or mertansine for treatment of CD44 expressing tumors. In early phase clinical trials, patients with breast or head and neck tumors treated with anti-CD44 conjugates experienced stabilized disease. A dose-limiting toxicity was associated with distribution of the antibody-drug conjugate to the skin, a site in the body with a high level of CD44. HA has been used as a drug carrier and a ligand on liposomes or nanoparticles to target drugs to CD44 overexpressing cells. Drugs can be attached to HA via the carboxylate on the glucuronic acid residue, the hydroxyl on the N-acetylglucosamine or the reducing end which are located on a repeating disaccharide. Drugs delivered in HA-modified liposomes exhibited excellent antitumor activity both in vitro and in murine tumor models. The HA matrix is also a potential target for anticancer therapies. By manipulating the interaction of HA with cell surface receptors, either by degrading it with hyaluronidase or by interfering with CD44-HA interactions using soluble CD44 proteins, tumor progression was blocked. Finally, cytotoxic drugs or prodrug converting enzymes can be attached to the HA matrix to generate a cytotoxic fence around the tumor. This review describes how the complex interplay among cancer biology, the CD44-HA interaction, drug carriers and drug targeting has been used to improve anticancer therapies. As these approaches evolve, they hold forth the prospect of significantly improved targeted anticancer treatments. PMID: 18547053 [PubMed - as supplied by publisher]