Dry-reagent gold nanoparticle-based lateral flow biosensor for the simultaneous detection of Vibrio cholerae serogroups O1 and O139

Cholera is a communicable disease caused by consumption of contaminated food and water. This potentially fatal intestinal infection is characterised by profuse secretion of rice watery stool that can rapidly lead to severe dehydration and shock, thus requiring treatment to be given immediately. Epidemic and pandemic cholera are exclusively associated with Vibrio cholerae serogroups O1 and O139. In light of the need for rapid diagnosis of cholera and to prevent spread of outbreaks, we have developed and evaluated a direct one-step lateral flow biosensor for the simultaneous detection of both V. cholerae O1 and O139 serogroups using alkaline peptone water culture. Serogroup specific monoclonal antibodies raised against lipopolysaccharides (LPS) were used to functionalize the colloidal gold nanoparticles for dual detection in the biosensor. The assay is based on immunochromatographic principle where antigen-antibody reaction would result in the accumulation of gold nanoparticles and thus, the appearance of a red line on the strip. The dry-reagent dipstick format of the biosensor ensure user-friendly application, rapid result that can be read with the naked eyes and cold-chain free storage that is well-suited to be performed at resource-limited settings.     

Chlorophyllase versus pheophytinase as candidates for chlorophyll dephytilation during senescence of broccoli

Degradation of chlorophylls during senescence is a highly regulated process which requires the concerted action of several enzymes. Traditionally, it has been stated that the dismantling process of the chlorophyll molecule begins with a dephytilation step, followed by Mg²⁺ removal and other breakdown reactions. Recently, new evidence suggests the possibility of a rearrangement in the first two steps of this process, occurring Mg²⁺ removal prior to the loss of the phytol side chain. With the purpose of approximating to the real sequential order of these reactions and to assess if dephytilation occurs on intact (catalyzed by chlorophyllase) or Mg-free (catalyzed by pheophytinase) chlorophyll, expression of both genes was analyzed in broccoli tissue during senescence. Samples of broccoli florets treated with plant hormones, such as cytokinin and ethylene were utilized, as to assess the effect of such compounds on the expression of these genes. Results showed that chlorophyllase expression did not correlate to typical expression patterns for genes related to senescence, since a decrease in expression during senescence was found for one of the two chlorophyllase genes analyzed, and the hormonal-treatment effects on gene expression did not match those observed on chlorophyll content for both chlorophyllase genes. Pheophytinase expression patterns, on the other hand, displayed an increase in the first 3 days of induced senescence, followed by lower expression values towards the end of the experiment. Samples subjected to postharvest treatments mostly showed an inhibition of pheophytinase expression, especially in samples in which degradation of chlorophylls had been delayed. These results suggest that pheophytinase expression correlates to the visual manifestation of postharvest treatments, supporting the possibility that this enzyme is responsible for the dephytilation step in chlorophyll breakdown.     

Paracoccidioidomycosis Induced by Immunosuppressive Drugs in a Patient with Rheumatoid Arthritis and Bone Sarcoma: Case Report and Review of the Literature

Paracoccidioidomycosis (PCM) is a systemic mycosis caused by Paracoccidioides brasiliensis, which is endemic in many regions of Latin America. We describe the case of a 60-year-old man from a region endemic for PCM who presented with a long history of left hip pain. He had been treated over the past 3 years with immunosuppressive drugs (methotrexate, leflunomide, and adalimumab) for rheumatoid arthritis (RA). A hip radiograph showed lytic bone lesions, and a chest radiograph showed an expansive excavated lesion in the left lung, suggestive of a lung cancer with bone metastases. A left hip joint biopsy was inconclusive, but histological analysis of a surgical lung biopsy specimen was consistent with P. brasiliensis infection. Treatment with intravenous amphotericin B (50 mg/day) and hydrocortisone (25 mg/day) was initiated. However, increasing hip pain resulted in the amputation of the left lower limb, and the analysis of the surgical specimen revealed a diagnosis of bone sarcoma. Postoperatively, the patient developed sepsis and died approximately 1 month later. To our knowledge, this is the first report of PCM in a patient with RA who had been treated with immunosuppressive drugs, in particular TNF-α blocking agents. The atypical presentation (left hip pain alone) emphasizes the importance of considering PCM in the differential diagnosis of patients with pulmonary lesions and osteolytic lesions who live in a region endemic for PCM. This case report also demonstrates that health professionals in these regions must pay close attention to patients receiving immunosuppressive drugs because of the possibility of reactivating quiescent P. brasiliensis lesions.     

Characterization of the immunogenic and antigenic potential of putative lipoproteins from Leptospira interrogans

The search for a vaccine capable of conferring heterologous protection, through the identification of conserved and cross-protective antigens, remains an ongoing priority in leptospirosis research. In the present study, an in silico analysis was used to identify potentially protective lipoproteins from Leptospira interrogans serovar Copenhageni. Eight putative lipoproteins were selected (LIC10009, LIC10054, LIC10091, LIC11058, LIC11567, LIC13059, LIC13305, and LIC20172), cloned and expressed in Escherichia coli and purified by affinity chromatography. The recombinant proteins were used to inoculate mice and the subsequent humoral immune response was evaluated by ELISA. Seven of the potential lipoproteins induced a significant IgG response. Furthermore, all of the recombinant proteins were recognized by antibodies present in the sera of severe leptospirosis patients. These putative lipoproteins exhibited potential for further evaluation as prospective vaccine candidates.     

On the taxonomic status of some Glyptodontidae (Mammalia,Xenarthra, Cingulata) from the Pleistocene of South America

The anatomical and taxonomic knowledge of some groups of Glyptodontidae (Mammalia, Cingulata) is still very poor. In addition, a strict typological/morphological taxonomic criterion was used in recognizing many taxa, especially during the second half of the 19th century and the first of the 20th century. This particular situation resulted in a clear overestimation diversity, mainly with respect to the South American glyptodonts. In this scenario, this paper analyzes the taxonomic status of some Glyptodontinae through a precise comparative study with well characterized taxa. The main results show that the genera Pseudothoracophorus Castellanos (P. depressus) and Chlamydotherium Lund, one species of the genus “Boreostracon” Simpson (B. corondanus), and one species of the genus Glyptodon Owen (G. falkneri), actually represents juvenile specimens referable to Glyptodon Owen; the genus Neothoracophorus Ameghino (N. elevatus) could be related either to Glyptodon Owen or Glyptotherium Osborn. Another species, Heteroglyptodon genuarioi, presents an almost identical morphology compared with the recognized species of Glyptodon (e.g. G. munizi and G. reticulatus). In this sense, the diagnostic characters described for Glyptodon perforatus Ameghino, a taxon with biostratigraphic relevance since it is characteristic of the Lujanian Age/Stage (late Pleistocene-early Holocene), are also present in other species of Glyptodon, especially G. reticulatus and G. clavipes, very frequent taxa in southern South America.     

Removal of methyl parathion and tetrachlorvinphos by a bacterial consortium immobilized on tezontle-packed up-flow reactor

A tezontle-packed up-flow reactor (TPUFR) with an immobilized bacterial consortium for biological treatment of methyl-parathion and tetrachlorvinphos was evaluated. These organophosphate pesticides are widely used in Mexico for insect and mite control, respectively. With the aim of developing a tool for pesticide biodegradation, four flow rates (0.936, 1.41, 2.19, and 3.51 l/h) and four hydraulic residence times (0.313, 0.206, 0.133, and 0.083 h) were evaluated in a TPUFR. In the bioreactor, with an operating time of 8 h and a flow of 0.936 l/h, we obtained 75% efficiency in the removal of methyl-parathion and tetrachlorvinphos. Their adsorptions in the volcanic rock were 9% and 6%, respectively. It was demonstrated that the removal of pesticides was due to the biological activity of the immobilized bacterial consortium. We confirmed the decrease in toxicity in the treated effluent from the bioreactor through the application of acute toxicity tests on Eisenia foetida. Immobilization of a bacterial consortium using tezontle as a support is innovative and an economical tool for the treatment of mixtures of organophosphorus pesticide residues.     

Trypanosoma evansi: Activities of adenine nucleotide degradation enzymes in cerebral cortex of infected rats

This study aimed to evaluate the activities of the ectoenzymes NTPDase and 5′-nucleotidase in synaptosomes from cerebral cortex of rats experimentally infected with Trypanosoma evansi. The animals were divided in four groups (n = 10) according to the time and degree of parasitemia (groups A, B, C and D). The animals from group A were euthanized on day 3 (low parasitemia), group B on day 5 (high parasitemia) and group C on day 15 (low parasitemia). Group D consisted of healthy rats (not-infected, n = 15) and were divided in three periods (n = 5) in order to compare with the infected groups. After euthanasia, cerebral cortex was removed for the preparation of synaptosomes and enzymatic assays. Group A showed no changes in enzymatic activities compared with control. The hydrolysis of ATP, ADP and AMP by the enzymes NTPDase and 5′-nucleotidase were increased (P < 0.05) in group B (38%, 140% and 61%, respectively) when compared with control. In the group C it was observed a decreased (22%) hydrolysis of ATP when compared with control group. The activities of NTPDase and 5′-nucleotidase in synaptosomes alters the acute phase of the disease when the number of circulating parasites is high, thus the change observed is probably due to the parasitemia.     

Tenascin-C in the extracellular matrix promotes the selection of highly proliferative and tubulogenesis-defective endothelial cells

The extracellular matrix (ECM) contains important cues for tissue homeostasis and morphogenesis. The matricellular protein tenascin-C (TN-C) is overexpressed in remodeling tissues and cancer. In the present work, we studied the effect of different ECM—which exhibited a significant diversity in their TN-C content—in endothelial survival, proliferation and tubulogenic differentiation: autologous (endothelial) ECM devoid of TN-C, but bearing large amounts of FN; fibroblast ECM, bearing both high TN-C and FN contents; and finally, glioma-derived matrices, usually poor in FN, but very rich in TN-C. HUVECs initially adhered to the immobilized matrix produced by U373 MG glioma cells, but significantly detached and died by anoikis (50 to 80%) after 24 h, as compared with cells incubated with endothelial and fibroblast matrices. Surviving endothelial cells (20 to 50%) became up to 6-fold more proliferative and formed 74–97% less tube-like structures in vitro than cells grown on non-tumoral matrices. An antibody against the EGF-like repeats of tenascin-C (TN-C) partially rescued cells from the tubulogenic defect, indicating that this molecule is responsible for the selection of highly proliferative and tubulogenic defective endothelial cells. Interestingly, by using defined substrata, in conditions that mimic glioma and normal cell ECM composition, we observed that fibronectin (FN) modulates the TN-C-induced selection of endothelial cells. Our data show that TN-C is able to modulate endothelial branching morphogenesis in vitro and, since it is prevalent in matrices of injured and tumor tissues, also suggest a role for this protein in vascular morphogenesis, in these physiological contexts.