Alicia Graciela Cid

Validation of kinetic modeling of progesterone release from polymeric membranes

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How long can culturable bacteria and total DNA persist in environmental waters? The role of sunlight and solid particles.

In this work, sunlight inactivation of two indicator bacteria in freshwater, with and without solid particles, was studied and the persistence of culturable cells and total DNA was compared. Environmental water was used to prepare two matrices, with and without solid particles, which were spiked with Escherichia coli and Enterococcus faecalis. These matrices were used to prepare microcosm bags that were placed in two containers: one exposed to sunlight and the other in the dark. During one month, samples were removed from each container and detection was done by membrane filter technique and real-time PCR. Kinetic parameters were calculated to assess sunlight effect. Indicator bacteria without solid particles exposed to sunlight suffered an immediate decay (<4h) compared with the ones which were shielded from them. In addition, the survival of both bacteria with solid particles varied depending on the situation analyzed (T99 from 3 up to 60days), being always culturable E. coli more persistent than E. faecalis. On the other side, E. faecalis DNA persisted much longer than culturable cells (T99>40h in the dark with particles). In this case active cells were more prone to sunlight than total DNA and the protective effect of solid particles was also observed. Results highlight that the effects caused by the parameters which describe the behavior of culturable microorganisms and total DNA in water are different and must be included in simulation models but without forgetting that these parameters will also depend on bacterial properties, sensitizers, composition, type, and uses of the aquatic environment under assessment.

New Teaching Strategies to Improve Student Performance in Fundamentals of Biotechnology

Fundamentals in Biotechnology is part of the Chemical Engineering curriculum at the National University at Salta, in northwest Argentina. This course, given for four months in the fourth year of a five-year program of study, includes concepts of general microbiology, biochemistry, and industrial microbiology and is the first contact by the students with biological issues. Probably due to the long content of the course and to the lack of previous knowledge of biological and microbiological concepts, students have a lot of difficulty passing this course. In order to reach a better understanding of the concepts, to encourage students to learn biotechnology, and to develop critical thinking skills with the ultimate aim of improving performance, two new strategies were adopted, which consisted of including “Complementary Activities” and an “Integration Seminar.”

Acanthamoeba in the eye, can the parasite hide even more? Latest developments on the disease

Acanthamoeba spp. is a free living protozoan in the environment, but can cause serious diseases. Acanthamoeba keratitis (AK), a severe and painful eye infection, must be treated as soon as possible to prevent ulceration of the cornea, loss of visual acuity, and eventually blindness or enucleation. Although the disease affects principally contact lens (CLs) wearers, it is recognized nowadays as a cause of keratitis also in non-CLs wearers. Although the number of infections caused by these amoebae is low, AK is an emerging disease presenting an extended number of cases each year worldwide mostly due to the increasing use of CLs, but also to better diagnostic methods and awareness. There are two principal causes that lead to severe outcomes: misdiagnosis or late diagnosis of the causal agent, and lack of a fully effective therapy due to the existence of a highly resistant cyst stage of Acanthamoeba. Recent studies have reported different genotypes that have not been previously associated with this disease. In addition, Acanthamoeba can act as a reservoir for phylogenetically diverse microorganisms. In this regard, recently giant viruses called Pandoravirus have been found within genotypes producing keratitis. What potential risk this poses is not yet known. This review focuses on an overview of the present status and future prospects of this re-emerging pathology, including features of the parasite, epidemiology, clinical aspects, diagnosis, and treatment.

Hydatid Disease: Current Status of Chemotherapy and Drug Delivery Systems

Fil: Elissondo, Maria Celina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Biologia. Laboratorio de Zoonosis Parasitarias; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas; Argentina