Outbreak of gastroenteritis caused by the pandemic Vibrio parahaemolyticus O3:K6 in Mexico

During 2003 and during late September of 2004, more than 1230 cases of gastroenteritis were reported in the south of Sinaloa State, north-western Mexico. All cases were attributed to the consumption of raw or undercooked shrimp collected at the Huizache-Caimanero lagunary system. Vibrio parahaemolyticus was identified by standard biochemical methods, and many strains were positive for PCR amplifications of the tlh and tdh genes and negative for the trh gene. A representative strain belonged to the O3:K6 serogroup. This is the first outbreak of gastroenteritis caused by the pandemic strains of O3:K6 V. parahaemolyticus in México.     

Ecophysiology and distribution of the endemic leafless spurgeEuphorbia aphylla and the introducedE. tirucalli (Euphorbiaceae,Euphorbia sect.Tirucalli) in the Canary Islands

The leafless spurgeEuphorbia aphylla (Euphorbiaceae), an endemic species restricted to several of the Canary Islands where it inhabits coastal and arid localities, expresses Crassulacean Acid Metabolism (CAM) when it is subjected to summer drought. A flexible CAM is consistent with the general ecology of the species. It is the only member of sect.Tirucalli native to the Canary Islands and is at the north-western edge of the section's biogeographical range. The other members of the section have a paleotropic distribution and are found throughout Africa. Many of them are regarded as obligate CAM plants, includingE. tirucalli which was used as a comparison in ecophysiological experiments examining the response ofE. aphylla to drought and temperature.     

Tree killing by herbicide producing ants for the establishment of pureTococa occidentalis populations in the Peruvian Amazon

Populations ofTococa occidentalis (Melastomataceae) and the inhabiting ants (Myrmelachista sp.) were observed for more than eight months in the Peruvian Amazon (Sira mountains). They represent a complex coevolutionary system: the plants offer shelter (leaf domatia, hollow stems) and food (leaf glands), whereas the ants kill all surrounding plants, including large trees up to 10 m, by chemical weapons. Experiments with exposed plants revealed a highly specialized way to attack meristematic tissue and leaf nervature, which leads to a quick decay of the plant individuals. The clearing of the vegetation by the ants allows theTococa population to expand mostly by vegetative shoots to large monocultures (up to 30 m in diameter) free from any other plant species. Artificially introduced plant individuals, from differentT. occidentalis populations, are regarded as a foreign species by the ants.The succession of such aTococa-Myrmelachista system begins with one or a few founder plants on a light place in the midst of the vegetation.Myrmelachista soon inhabits their host plants which otherwise would not survive and begin to clear the place from all foreign plant species.Tococa expands quickly, forming circle shaped populations. Distantly situated canopy trees shade theTococa population after a number of years and cause their decay. The whole place appears contaminated for years and no other plant can establish itself. Some of the consequences of these open places are erosion and a severe influence on the regeneration of the forest.     

Brazilian green propolis on Helicobacter pylori infection. a pilot clinical study

Recent in vitro studies suggest that propolis and some of its phenolic components are able to inhibit Helicobacter pylori growth. To date, there are no clinical studies. AIMS: To evaluate the effect of Brazilian green propolis on H. pylori-infected individuals. PATIENTS AND METHODS: Eighteen (11 females, 7 males, mean age 47 years) participants were included. Before treatment, all participants were submitted to gastroscopy, and H. pylori infection was confirmed by histology, urease test, and (13)C-urea breath test (UBT). Participants with UBT showing a delta over baseline (DOB) value higher than 4 per thousand were considered positive for H. pylori infection. Twenty drops from an alcoholic preparation of Brazilian green propolis were administered three times a day for 7 days. Clinical evaluation and UBT were performed at 1-3 days and at 40 days after the end of therapy to evaluate H. pylori suppression or eradication, respectively. RESULTS: All participants took all medication and completed the study. Eighty-three percent of the subjects did not succeed in suppressing or eradicating H. pylori. Two participants reached partial suppression after treatment, but became positive again at UBT performed 40 days after treatment. Another participant presented negative at UBT 40 days after treatment, not confirmed by a second UBT performed 100 days after treatment. CONCLUSIONS: Brazilian green propolis used in popular dose showed minimal effect on H. pylori infection. Larger studies with longer duration, larger dose, and different frequency of administration of propolis extract should be undertaken to define its role on H. pylori therapy.     

35S-β-glucuronidase gene blocks biological effects of cotransferred iaa genes

The iaaM and iaaH genes of Agrobacterium tumefaciens and Agrobacterium rhizogenes play an important role in crown gall and hairy root disease. The iaaM gene codes for tryptophan monooxygenase which converts tryptophan into indole-3-acetamide (IAM). IAM is converted into the auxin indole-3-acetic acid (IAA) by indoleacetamide hydrolase, encoded by the iaaH gene. In functional studies on the activity of the iaa genes of the TB region of the A. tumefaciens biotype III strain Tm4, the frequently used 35S--glucuronidase (35S-UidA or GUS) marker gene was found to inhibit IAA synthesis and root induction encoded by the TB iaa genes. To exert this inhibition, the 35S-UidA gene must be cotransferred with the iaaH gene. The 35S promoter alone is sufficient to cause the inhibitory effect.     

La cognition dans le trouble obsessionnel compulsif : à l’intersection de la clinique et de la neuro-imagerie

The investigation of neural activity in OCD (Obsessive Compulsive Disorder) has allowed to link obsessive compulsive symptoms and cortico-striatal dysfunction. In the present article, we try to show the significance of cognition in an integrative physiopathologic model of OCD. Clinically, patients are unable to inhibit irrelevant thoughts or actions. In a cognitive way, decision making, planification or organisation are impaired. Those impairments are related to an executive deficit, which depends on frontal structures. Finally, we present a current study which tries to identify executive deficit functions related to cerebral dysfunction in patients presenting different OCD features (washing, checking, hoarding).     

A methionine-choline-deficient diet elicits NASH in the immunodeficient mouse featuring a model for hepatic cell transplantation

Non-alcoholic staetohepatitis (NASH) is associated with fat deposition in the liver favoring inflammatory processes and development of fibrosis, cirrhosis and finally hepatocellular cancer. In Western lifestyle countries, NASH has reached a 20% prevalence in the obese population with escalating tendency in the future. Very often, liver transplantation is the only therapeutic option. Recently, transplantation of hepatocyte-like cells differentiated from mesenchymal stem cells was suggested a feasible alternative to whole organ transplantation to ameliorate donor organ shortage. Hence, in the present work an animal model of NASH was established in immunodeficient mice to investigate the feasibility of human stem cell-derived hepatocyte-like cell transplantation. NASH was induced by feeding a methionine/choline-deficient diet (MCD-diet) for up to 5 weeks. Animals developed a fatty liver featuring fibrosis and elevation of the proinflammatory markers serum amyloid A (SAA) and tumor necrosis factor alpha (TNFα). Hepatic triglycerides were significantly increased as well as alanine aminotransferase demonstrating inflammation-linked hepatocyte damage. Elevation of αSMA mRNA and collagen I as well as liver architecture deterioation indicated massive fibrosis. Both short- and long-term post-transplantation human hepatocyte-like cells resided in the mouse host liver indicating parenchymal penetration and most likely functional engraftment. Hence, the NASH model in the immunodeficient mouse is the first to allow for the assessment of the therapeutic impact of human stem cell-derived hepatocyte transplantation.     

Substrate-Induced Ubiquitylation and Endocytosis of Yeast Amino Acid Permeases

Many plasma membrane transporters are downregulated by ubiquitylation, endocytosis, and delivery to the lysosome in response to various stimuli. We report here that two amino acid transporters of Saccharomyces cerevisiae, the general amino acid permease (Gap1) and the arginine-specific permease (Can1), undergo ubiquitin-dependent downregulation in response to their substrates and that this downregulation is not due to intracellular accumulation of the transported amino acids but to transport catalysis itself. Following an approach based on permease structural modeling, mutagenesis, and kinetic parameter analysis, we obtained evidence that substrate-induced endocytosis requires transition of the permease to a conformational state preceding substrate release into the cell. Furthermore, this transient conformation must be stable enough, and thus sufficiently populated, for the permease to undergo efficient downregulation. Additional observations, including the constitutive downregulation of two active Gap1 mutants altered in cytosolic regions, support the model that the substrate-induced conformational transition inducing endocytosis involves remodeling of cytosolic regions of the permeases, thereby promoting their recognition by arrestin-like adaptors of the Rsp5 ubiquitin ligase. Similar mechanisms might control many other plasma membrane transporters according to the external concentrations of their substrates.