Photoinactivation of Escherichia coli using porphyrin derivatives with different number of cationic charges

The photodynamic effect of meso-substituted cationic porphyrins, 5-[4-(trimethylammonium)phenyl]-10,15,20-tris(2,4,6-trimethoxyphenyl)porphyrin iodide 1, 5,10-di(4-methylphenyl)-15,20-di(4-trimethylammoniumphenyl)porphyrin iodide 2 and 5-(4-trifluorophenyl)-10,15,20-tris(4-trimethylammoniumphenyl)porphyrin iodide 3, have been investigated in both homogeneous medium bearing photooxidizable substrates and in vitro on a typical gram-negative bacterium Escherichia coli. Absorption and fluorescence spectroscopic studies were compared in N,N-dimethylformamide. Fluorescence quantum yields (varphiF) of 0.10, 0.06 and 0.08 were calculated for porphyrins 1, 2 and 3, respectively. The singlet molecular oxygen, O2(1Deltag), production was evaluated using 9,10-dimethylanthracene yielding values of 0.66, 0.36 and 0.42 for porphyrins 1, 2 and 3, respectively. Guanosine 5'-monophosphate was used as biological substrate model. Similar decomposition of guanosine 5'-monophosphate was obtained using these cationic porphyrins as sensitizer. In biological medium, photosensitized inactivation of E. coli was analyzed using cells without and with one washing step. E. coli cultures were treated with sensitizer at 37 degrees C for 30 min in dark. In both procedures, a higher photoinactivation of cells (>99.999%) was found for cells treated with 10 microM of tricationic porphyrin 3 and irradiated for 5 min with visible light. Porphyrins 1 and 2 only show an important photodamage when the cells are irradiated without washing step. These results indicated that the tetracationic porphyrin 3 could be a promising sensitizer with potential applications in the photoinactivation of bacterial cells by photodynamic therapy.     

Protection against malaria induced by chirally modified Plasmodium falciparum's MSP-1 42 pseudopeptides

The C-terminal portion of the Plasmodium falciparum blood stage MSP-1 antigen plays a key role in invasion of human erythrocytes. The MSP-1(1282-1301) non-polymorphic 1585 peptide, from the processed MSP-1(42) fragment, is poorly immunogenic and highly alpha-helical [Angew. Chem. Int. Ed. 40 (2001) 4654]. Assessing the alpha-carbon asymmetry and its implication in the host immune response is proposed in this work to overcome the 1585 peptide's immunological properties. Accordingly, the effect of incorporating single D-amino acids and psi-[CH(2)-NH] isoster bonds into the 1585 peptide was examined both at the immunogenic and 3D-structure levels. Therefore, specific binding to RBCs is promoted by site-directed chiral modifications on the native peptide as well as by simultaneously combining specific D-substitutions with psi-[CH(2)-NH] isoster bonds transforming this molecule into a high specific HLAbeta1*1101 allele binder. D-analog pseudopeptide immunized animals induced antibodies selectively recognizing a recombinant as well as native MSP-1(42) and MSP-1(33) fragments. Protection and low parasitemia levels were induced in Aotus monkeys immunized with the EVLYL(dK)PLAGVYRSLKKQLE analog. Peptide alpha-carbon chiral transformation is therefore an important target for structural modulation and, consequently, represents a novel approach towards designing multi-component subunit-based malarial vaccines.     

Evidence that osteogenic progenitor cells in the human tunica albuginea may originate from stem cells: implications for peyronie disease

Tissue ossification in Peyronie disease (commonly known as Peyronie's disease [PD]), a localized fibrotic lesion within the tunica albuginea (TA) of the penis, may result from osteogenic differentiation of fibroblasts, myofibroblasts, and/or adult stem cells in the TA, and may be triggered by chronic inflammation, oxidative stress, and profibrotic factors like transforming growth factor beta 1 (TGFB1). In this study, we have investigated whether cultures of cells from normal TA and PD plaques undergo osteogenesis, express markers for stem cells, and originate other cell lineages via processes modulated by TGFB1. We found that TA and PD cells in osteogenic medium (OM) expressed osteogenic markers, alkaline phosphatase, and osteopontin and underwent calcification. PD cells, but not TA cells, formed foci in soft agar that were positive for alkaline phosphatase and calcification and expressed the mRNAs for osteoblast-specific factors pleiotrophin and periostin and bone morphogenic protein 2. Both cultures expressed stem cell marker CD34 antigen but not protein tyrosine phosphatase, receptor type c. TA and PD cells expressed smooth-muscle cell markers smoothelin and transgelin. None of the cultures underwent adipogenesis in adipogenic medium. Incubation with TGFB1 increased osteogenesis and myofibroblast differentiation and reduced CD34 antigen expression in both cultures. TA and PD cells modulated the differentiation of the multipotent C3H 10T(1/2) cells in dual cultures, into osteoblasts and myofibroblasts. In conclusion, both TA and PD cultures contain cells, presumably stem cells, that undergo osteogenic and myofibroblast differentiation, and may induce these processes by paracrine interactions. This may explain progression of fibrosis in the PD plaque and its eventual calcification.     

A robust two-way semi-linear model for normalization of cDNA microarray data

Background  

Normalization is a basic step in microarray data analysis. A proper normalization procedure ensures that the intensity ratios provide meaningful measures of relative expression values.     

Cytologic features of pilocytic astrocytoma in cerebrospinal fluid specimens

OBJECTIVE: To illustrate the cytomorphologic features of pilocytic astrocytoma (PA) in cerebrospinal fluid (CSF) samples. STUDY DESIGN: A search of records from 1965 to 2001 was performed to identify all patients with a diagnosis of PA in whom CSF samples were examined. Slides from CSF samples originally reported as atypical, suspicious or positive were reviewed and the cytomorphologic features assessed. RESULTS: Two hundred ninety-three patients with a diagnosis of PA were identified. Of these, 44 had a total of 65 cytologic preparations of CSF. In 34 patients (77.2%) the CSF cytology was negative, in 5 (11.4%) either atypical or suspicious, and in 5 (11.4%) positive for neoplastic cells. The tumors in the 5 positive cases arose in the cerebellar hemispheres (2), cerebellar vermis (1), thalamus (1) and tectum with extension into the fourth ventricle (1). All positive samples were hypercellular, with an average of 5 cell clusters per case (range, 3-11). The clusters were composed of cohesive epithelioid cells with a mean of 8 cells per cluster. In addition, some cases had scattered, isolated, single cells. These single neoplastic cells had prominent, hairlike cytoplasmic processes. The cells in clusters appeared epithelioid, with oval nuclei, mild nuclear pleomorphism, finely or slightly coarsely granular chromatin and cobweblike cytoplasm. CONCLUSION: The cytomorphologic features of PAs recapitulate their histologic characteristics. The tumor cells are recognizable in CSF samples and readily distinguishable from histiocytes and ependymal cells.     

Genomic insights into acute inflammatory lung injury

Acute lung injury (ALI) is a devastating syndrome (usually associated with sepsis) that represents a major healthcare burden in the United States. We have focused our studies on unraveling the genetic underpinnings of this syndrome utilizing a candidate gene approach to identify novel genes for ALI susceptibility. Two novel genes identified by this approach include pre-B cell colony-enhancing factor (PBEF) and the gene for myosin light chain kinase (MLCK). PBEF protein levels were elevated in human bronchoalveolar lavage and serum samples from patients with ALI, and DNA sequencing identified two single nucleotide polymorphisms in the PBEF promoter (T-1001G, C-1543T) that were overrepresented in patients with sepsis-induced ALI. More recently, we found MLCK single polymorphisms and haplotypes to be associated with human ALI with unique variants observed in African-Americans with ALI. Thus genomic and genetic approaches represent powerful strategies in the identification of novel candidate genes and potential targets for ALI therapies.     

Features of crossing-over in virus-infected tomato

The evidence of increased crossing over rate in tomato hybrids infected with TAV (Tomato aspermy virus), PVX (Potato virus X), TMV (Tobacco mosaic virus), TMV+PVX indicates the recombinogenic effect of viral infection. Cytological studies of the early diakinesis in healthy and virus-infected tomato revealed significant changes in chiasma number and position. The most significant changes were established for bivalents with two interstitial chiasmata and with one terminal and one interstitial. The data obtained indicate redistribution of the chiasmata position and induction of additional exchanges. The virus-induced recombination is segment-specific and depends on the host plant genotype, virus infection and the interaction between them.     

Brain‐derived neurotrophic factor selectively regulates dendritogenesis of parvalbumin‐containing interneurons in the main olfactory bulb through the PLCγ pathway

Molecular mechanisms of neurotrophin signaling on dendrite development and dynamics are only partly understood. To address the role of brain‐derived neurotrophic factor (BDNF) in the morphogenesis of GABAergic neurons of the main olfactory bulb, we analyzed mice lacking BDNF, mice carrying neurotrophin‐3 (NT3) in the place of BDNF, and TrkB signaling mutant mice with a receptor that can activate phospholipase Cγ (PLCγ) but is unable to recruit the adaptors Shc/Frs2. BDNF deletion yielded a compressed olfactory bulb with a significant loss of parvalbumin (PV) immunoreactivity in GABAergic interneurons of the external plexiform layer. Dendrite development of PV‐positive interneurons was selectively attenuated by BDNF since other Ca²⁺‐binding protein‐containing neuron populations appeared unaffected. The deficit in PV‐positive neurons could be rescued by the NT3/NT3 alleles. The degree of PV immunoreactivity was dependent on BDNF and TrkB recruitment of the adaptor proteins Shc/Frs2. In contrast, PLCγ signaling from the TrkB receptor was sufficient for dendrite growth in vivo and consistently, blocking PLCγ prevented BDNF‐dependent dendrite development in vitro. Collectively, our results provide genetic evidence that BDNF and TrkB signaling selectively regulate PV expression and dendrite growth in a subset of neurochemically‐defined GABAergic interneurons via activation of the PLCγ pathway. © 2006 Wiley Periodicals, Inc. J Neurobiol, 2006     

Cadmium exposure modifies lactotrophs activity associated to genomic and morphological changes in rat pituitary anterior lobe

Cadmium (Cd) is widely used in industrial applications and is an important contaminant of agricultural products. As an endocrine disruptor, Cd modifies the hormone release of pituitary anterior lobe (PAL). This work was undertaken to evaluate a possible association between phospholipase D (PLD) and prolactin mRNA expressions and the activity of lactotrophs and folliculostellate cells (FSC) in PAL of Cd exposed adult male Wistar rats (Cd, 0.133 mM per liter for 2 months). The PALs were submitted to immunohistochemical and morphometric analysis to determine the percentage of lactotrophs (PRL-ir) and FSC (S-100-ir). Cultured PAL cells were stained with Hoechst 33258 to determine the presence of alterations in nuclear morphology consistent with apoptosis. The expressions of PLD and prolactin mRNA were assessed by RT-PCR. Cd treated rats showed a decrease of PLD mRNA levels that can be associated to both high number of apoptotic cells and increase of S-100 protein expression in FSC. Cd decreased prolactin mRNA expression, number of lactotrophs and percentage of PRL-ir suggesting a low availability of prolactin to be secreted from PAL. Cd modifies the lactotrophs activity of pituitary gland through biochemical, genomic and morphological changes and contributes directly or indirectly to the levels of serum prolactin.     

The relationship between fish assemblages and the helminth communities of a prey fish, in a group of small shallow lakes

Galaxias maculatus (small puyen) is an abundant native fish distributed in lakes and rivers of the Patagonia, and it is the frequent prey of other fishes, fish-eating birds, and mammals. Previous studies have shown that it is parasitized by 33 metazoan species and that the richness and composition of the parasite communities vary between lakes. The aim of the present work was to analyze the relationship between the composition of fish assemblages and the helminth component community structure of G. maculatus . Ten environmentally similar, small, shallow lakes, belonging to the Nahuel Huapi Lake basin, were chosen because of the differences in the native fish assemblages. Parasite community structure in G. maculatus varied according to the fish assemblage of each lake. The presence of the piscivorous fish Percichthys trucha regularly produced variations in the composition and richness at the component and infracommunity levels, as well as the percentage of autogenic parasite species in G. maculatus .