The mechanistic aspects of Escherichia coli photodynamic inactivation (PDI) have been investigated in bacteria treated with 5,10,15-tris[4-(3-N,N,N-trimethylammoniumpropoxy)phenyl]-20-(4-trifluoromethylphenyl)porphyrin iodide (A3B3+) and visible light. The photosensitization activity of A3B3+ porphyrin was compared with that of 5,10,15,20-tetra(4-N,N,N-trimethylammonium phenyl)porphyrin p-tosylate (TMAP4+), which is an active tetracationic sensitizer to eradicate bacteria. The PDI damages on plasmid and genomic DNA were analyzed by electrophoresis. DNA photocleavage was observed after a long period of irradiation, when the bacterial cells are largely photoinactivated. Transmission electron microscopy (TEM) revealed structural changes with appearance of low density areas into the cells and irregularities in cell barriers, which could affect the normal cell membrane functionality. Also, damages on the cell-wall were not detected by scanning electron microscopy (SEM) and release of intracellular biopolymers was not found after PDI. These results indicate that the photodynamic activity of these cationic porphyrins produces DNA photodamage after a long period of irradiation. Therefore, an interference with membrane functions could be the main cause of E. coli photoinactivation upon short PDI treatments.

Tripeptidyl-peptidase 1 (TPP1) null or residual activity occurs in neuronal ceroid lipofuscinosis (NCL) with underlying TPP1/CLN2 mutations. A survey of 25 South American CLN2 affected individuals enabled the differentiation of two phenotypes: classical late-infantile and variant juvenile, each in approximately 50% of patients, with residual TPP1 activity occurring in approximately 32%. Each individual was assigned to one of three subgroups: (I) n=11, null TPP1 activity in leukocytes; (II) n=8, residual TPP1 activity of 0.60–15.85 nmol/h/mg (nr 110–476); (III) n=6, activity not measured in leukocytes. Curvilinear bodies (CB) appeared in almost all studied CLN2 subjects; the only exceptions occurred in cases of subgroup II: two individuals had combined CBs/fingerprints (FPs), and one case had pure FPs. There were 15 mutations (4 first published in this paper, 3 previously observed in South America by our group, and 8 previously observed by others). In subgroup I, mutations were either missense or nonsense; in subgroups II and III, mutations prevailed at the non-conserved intronic site, c.887-10A>G (intron 7), and to a lesser extent at c.89+5G>C (intron 2), in heterozygous combinations. Grouping phenotypically and genetically known individuals on the basis of TPP1 activity supported the concept that residual enzyme activity underlies a protracted disease course. The prevalence of intronic mutations at nonconserved sites in subgroup II individuals indicates that some alternative splicing might allow some residual TPP1 activity.

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1) The study confirmed NCL disease in 122 subjects. Phenotypic studies comprised epileptic seizures and movement disorders, ophthalmology, neurophysiology, image analysis, rating scales, enzyme testing, and electron microscopy, carried out under a consensus algorithm; 2) DNA screening and validation of mutations in genes PPT1 (CLN1), TPP1 (CLN2), CLN3, CLN5, CLN6, MFSD8 (CLN7), and CLN8: characterization of variant types, novel/known mutations and polymorphisms; 3) Progress of the epidemiological picture in Latin America; and 4) NCL-like pathology studies in progress. The Translational Research Program was highly efficient in addressing the misdiagnosis/underdiagnosis in the NCL disorders. The study of "orphan diseases" in a public administrated hospital should be adopted by the health systems, as it positively impacts upon the family's quality of life, the collection of epidemiological data, and triggers research advances. This article is part of a Special Issue entitled: "Current Research on the Neuronal Ceroid Lipofuscinoses (Batten Disease)".

We report the enhanced bactericidal activity of ofloxacin in drug‐containing Eudragit E100® dispersions (EuCl‐OFX) against Pseudomonas aeruginosa and the effect of the cationic polymer on bacterial membrane. Organisms treated with EuCl‐OFX showed changes in cell morphology, altered outer membrane (OM) and cytoplasm with low electrodensity areas. Zeta potential of bacterial surface was shifted to positive. Sensitization to lytic agents was also observed. A profound effect on bacterial size, granularity and membrane depolarization was found by flow cytometry. Cultures exposed to drug‐free polymer also showed some damaged bacterial membranes, but there was no significant cell death. Inhibition of P. aeruginosa by EuCl‐OFX may involve surface effect and, to some extent, permeation effect. The cationic polymer act to mitigate the electronegativity of cell surface in the process of disorganizing the OM, rendering it more permeable to antibiotic. In addition, cytoplasmic membrane depolarization turns bacterial cell more vulnerable. The effects on membranes combined with the mechanism of action of quinolone explain the improved bactericidal action exhibited by EuCl‐OFX. The behavior described for Eudragit E100® against P. aeruginosa may be a useful tool to broaden the spectrum of antibiotics whose clinical use is limited by the impermeability of the bacterial OM.