Distribution and natural infection status of synantrophic triatomines (Hemiptera: Reduviidae), vectors of Trypanosoma cruzi,reveals new epidemiological scenarios for chagas disease in the Highlands of Colombia

IntroductionUpdating the distribution and natural infection status of triatomine bugs is critical for planning, prioritizing, and implementing strategies to control Chagas disease (CD), especially after vector reduction programs. After carrying out a control program, the Department of Boyaca contains the highest number of Colombian municipalities certified by PAHO to be free of intradomiciliary transmission of Trypanosoma cruzi by Rhodnius prolixus. The present work describes the spatial distribution, natural infection (NI), and molecular characterization of T. cruzi in synanthropic triatomines from the Department of Boyaca in 2017 and 2018.Materials and methodsAn entomological survey was conducted in 52 municipalities in Boyaca known to have had previous infestations of triatomine bugs. Insects were collected through active searches carried out by technical personnel from the Secretary of Health and community members using Triatomine Collection Stations (PITs-acronym in Spanish). For evaluation of natural infection, triatomines were identified morphologically and grouped in pools of one to five individuals of the same species collected in the same household. DNA derived from the feces of each pool of insects was analyzed by PCR for the presence of T. cruzi using primers flanking the satellite DNA of the parasite. SL-IR primers were used to differentiate TCI from the other DTUs and to identify different genotypes. The distribution of the collected triatomines was analyzed to determine any vector hotspots using spatial recreation.ResultsA total of 670 triatomine bugs was collected, belonging to five species: Triatoma dimidiata (73.2%), Triatoma venosa (16.7%), Panstrongylus geniculatus (5.7%), Rhodnius prolixus (4.4%), and Panstrongylus rufotuberculatus (0.4%), from 29 of the 52 municipalities. In total, 71.6% of the bugs were collected within houses (intradomiciliary) and the rest around the houses (peridomiciliary). Triatoma dimidiata was the most widely distributed species and had the highest natural infection index (37.8%), followed by T. venosa and P. geniculatus. TcI was the only DTU found, with the TcI Dom genotype identified in 80% of positive samples and TcI sylvatic in the other insects. Spatial analysis showed clusters of T. dimidiata and T. venosa in the northeast and southwest regions of Boyaca.ConclusionsAfter some municipalities were certified free of natural transmission within houses (intradomiciliary transmission) of T. cruzi by R. prolixus, T. dimidiata has become the most prevalent vector present, and represents a significant risk of resurgent CD transmission. However, T. venosa, P. geniculatus, and P. rufotuberculatus also contribute to the increased risk of transmission. The presence of residual R. prolixus may undo the successes achieved through vector elimination programs. The molecular and spatial analysis used here allows us to identify areas with an ongoing threat of parasite transmission and improve entomological surveillance strategies.     

Fetal cardiovascular responses to asphyxia induced by decreased uterine perfusion

Cardio-respiratory responses to asphyxia produced by decreased uterine perfusion were studied in 15 sheep fetuses. In chronic (spinal-anesthetized) and acute (inhalation-anesthetized) preparations, we measured fetal PO2, PCO2, pH, heart rate, arterial and umbilical venous pressures at rest and 5 min after controlled reductions of maternal aortic blood flow. Umbilical blood flow was determined by electromagnetic flow transducer on the fetal descending aorta with the iliac arteries ligated, in conjunction with radionuclide-labelled microspheres. In contrast to previous studies in which fetal hypoxaemia was produced by decreased maternally inspired O2 concentrations, decreasing degrees of uterine perfusion were associated with increasing degrees of hypercapnea and acidemia, as well as hypoxaemia. In chronic experiments, heart rate and umbilical blood flow fell significantly in response to decreased uterine perfusion with all degrees of hypoxaemia studied. In acute experiments, during the control period, PO2 values were similar to those of chronic experiments while values for pH and umbilical blood flow were lower and those for umbilical vascular resistance were higher. In the acute experiments, hypoxic stresses identical to those in the chronic studies failed to produce significant hemodynamic changes, except for bradycardia in response to severe hypoxaemia. These differences were apparently due to the pharmacologic effects of halothane and the operative stresses.     

Effect of Age-Stiffening Tissues and Intraocular Pressure on Optic Nerve Damages

Age-stiffening of ocular tissues is statistically linked to glaucoma in the elderly. In this study, the effects of age-stiffening on the lamina cribrosa, the primary site of glaucomatous nerve damages, were modeled using computational finite element analysis. We showed that glaucomatous nerve damages and peripheral vision loss behavior can be phenomenologically modeled by shear-based damage criterion. Using this damage criterion, the potential vision loss for 30 years old with mild hypertension of 25mmHg intraocular pressure (IOP) was estimated to be 4%. When the IOP was elevated to 35mmHg, the potential vision loss rose to 45%; and age-stiffening from 35 to 60 years old increased the potential vision loss to 52%. These results showed that while IOP plays a central role in glaucomatous damages, age-stiffening facilitates glaucomatous damages and may be the principal factor that resulted in a higher rate of glaucoma in the elderly than the general population.     

Genbank accession #: AF 135190

Plant Molecular Biology -     

Antioxidative activity of new N-oxides of tertiary amines: membrane model and chromogen studies

Potential antioxidative activities of three series of newly synthesized N-oxides were studied. Individual components in each of the series differed in the lipophilicities and number of free radical scavenging groups. Various methods were used to determine their antioxidative efficiencies: Prevention of erythrocyte membrane lipid oxidation induced by UV irradiation and chromogen experiments in which antioxidative efficiencies of compounds were compared to that of the standard antioxidant Trolox (a water-soluble vitamin E analogue). Additionally, some hemolytic (pig erythrocytes) and differential scanning calorimetry (DSC) measurements were performed to determine a mechanism of the interaction between membranes and N-oxides. It was found that N-oxides, especially those of long alkyl chains (> C12H25), readily interacted with both, erythrocyte and liposomal membranes. No marked differences were found in their protection of erythrocytes against oxidation. In most cases inhibition of oxidation changed between 15% and 25%. Still, it was far better than in chromogen experiments where suppression of free radicals reached 20% in the best case. It may be concluded that antioxidative capabilities of N-oxides are moderate. Studies on the interaction mechanism showed that incorporation of particular compounds into model membranes varied. Hemolysing activities of compounds increased with the elongation of the alkyl chain but differed for corresponding compounds of particular series indicating that lipophilicity of compounds is not the only factor determing their interaction with erythrocyte membranes. DSC experiments showed that N-oxides, upon incorporation into 1,2-dipalmitoyl-3-sn-phosphatidylcholine liposomes, shifted the subtransition (Tp) and the main transition (Tm). The shifts observed depended on the alkyl chain length. The effects differed for each series. It seems that in the case of long alkyl chain compounds the domain formation may take place. Generally, the decrease of Tm was greatest for the same compounds that exhibited the best hemolytic efficacy. The same conclusion concerns the decrease of cooperativity of the main transition and the observed changes suggest an increase in membrane fluidity. Both, erythrocyte and DSC experiments seem to indicate that compounds of particular series incorporate in a somewhat different way into membranes.     

Redescription of the fish parasite Lernanthropus polynemi Richiardi, 1881 (Copepoda: Siphonostomatoida) and relegation of two congeners to synonymy

Lernanthropus polynemi Richiardi, 1881 is described, for the first time since its original discovery, based on the type-material found in the Museum für Naturkunde in Berlin, Germany. Morphological features of this parasite, which infects the commercially-caught fish Eleutheronema tetradactylum (Shaw), are described and illustrated, including those of the male, which is described for the first time. The types of another species from the same host, L. lappaceus Wilson, 1912, and deposited in the National Museum of Natural History in Washington DC, are also examined based on the type-specimens. The types of a third congener, L. trifoliatus Basset-Smith, 1898, also from the same host, are not available, but the original illustrations are studied. It is considered that the three nominal species described from E. tetradactylum represent a single taxon, and that L. lappaceus and L. trifoliatus be relegated to synonymy with L. polynemi.     

Amphiphilic amine-N-oxides with aliphatic alkyl chain act as efficient superoxide dismutase mimics, antioxidants and lipid peroxidation blockers in yeast

Amphiphilic 3-(alkanoylamino)propyldimethylamine-N-oxides with different length of the alkyl chain, i.e. different hydrophilic-lipophilic balance, act in micromolar concentrations as SOD mimics by lifting the inhibition of aerobic growth caused by SOD deletions in Saccharomyces cerevisiae. They also enhance the survival of sod mutants of S. cerevisiae exposed to the hydrophilic superoxide-generating prooxidant paraquat and the amphiphilic hydroperoxide-producing tert-butylhydroperoxide (TBHP), and largely prevent TBHP-induced peroxidation of isolated yeast plasma membrane lipids. Unlike the SOD-mimicking effect, the magnitude of these effects depends on the alkyl chain length of the amine-N-oxides, which incorporate into S. cerevisiae membranes, causing fluidity changes in both the hydrophilic surface part of the membrane and the membrane lipid matrix. Unlike wild-type strains, the membranes of sod mutants were found to contain polyunsaturated fatty acids; the sensitivity of the mutants to lipophilic pro-oxidants was found to increase with increasing content of these acids. sod mutants are useful in assessing pro- and antioxidant properties of different compounds.     

Plasma catecholamines in the hypoxaemic fetal rhesus monkey

To assess the response of the sympathoadrenal system of the primate fetus to oxygen deprivation, we measured plasma catecholamines in 8 chronically catheterized fetal rhesus monkeys. A range of fetal hypoxaemia was produced by having the mother inspire 15, 10, or 9% oxygen mixtures while tranquilized with ketamine. Catecholamines from fetal carotid and maternal femoral arteries were measured by radioenzymatic assay. Fetal plasma norepinephrine and epinephrine concentrations increased significantly at all levels of hypoxaemia, but dopamine increased only at very low fetal oxygen tensions. Norepinephrine levels exceeded those of epinephrine and dopamine under all conditions. Relatively more severe hypoxaemia was necessary to elevate concentrations of epinephrine above baseline as compared with norepinephrine. A negative exponential correlation (P less than 0.001) was found between both fetal arterial PO2 and oxygen content and plasma norepinephrine and epinephrine, which was qualitatively similar to that observed previously in the sheep fetus. Maternal catecholamines were found to increase during hypoxaemia as well, but to a lesser degree than in the fetus.