The life cycle and host specificity of Psychodiella sergenti n. sp. and Ps. tobbi n. sp. (Protozoa: Apicomplexa) in sand flies Phlebotomus sergenti and Ph. tobbi (Diptera: Psychodidae)

Two new gregarines in the recently erected genus Psychodiella (formerly Ascogregarina), Psychodiella sergenti n. sp. and Psychodiella tobbi n. sp., are described based on morphology and life cycle observations conducted on larvae and adults of their natural hosts, the sand flies Phlebotomus sergenti and Phlebotomus tobbi, respectively. The phylogenetic analyses inferred from small subunit ribosomal DNA (SSU rDNA) sequences indicate the monophyly of newly described species with Psychodiella chagasi. Ps. sergenti n. sp. and Ps. tobbi n. sp. significantly differ from each other in the life cycle and in the size of life stages. The sexual development of Ps. sergenti n. sp. (syzygy, formation of gametocysts and oocysts) takes place exclusively in blood-fed Ph. sergenti females, while the sexual development of Ps. tobbi n. sp. takes place also in males and unfed females of Ph. tobbi. The susceptibility of Phlebotomus perniciosus, Phlebotomus papatasi, Ph. sergenti, Ph. tobbi, and Phlebotomus arabicus to both gregarines was examined by exposing 1st instar larvae to parasite oocysts. High host specificity was observed, as both gregarines were able to fully develop and complete regularly the life cycle only in their natural hosts. Both gregarines are considered as serious pathogens in laboratory-reared colonies of Old World sand flies.     

Field growth characteristics of two aquatic carnivorous plants,Aldrovanda vesiculosa andUtricularia australis

Basic growth characteristics of two species of free-floating submerged carnivorous plants, the very rare and stenotopicAldrovanda vesiculosa and the very common and eurytopicUtricularia australis, were investigated in a 10/11-day field growth experiment within three nylon enclosures at two artificialAldrovanda sites in the T?eboň region, S Bohemia, Czech Republic, at the peak of a growing season. Growth ofAldrovanda was best at a meso-eutrophic site (biomass doubling time,T ₂, 8.4–10.7 days, mean growth of new leaf whorls 0.96 whorls days^?1, 1.6 developed branches per shoot) and slower at an oligo-mesotrophic site (T ₂ 17.2–21.5 days, growth of whorls 1.01 whorls days^?1, 0.1–0.5 branches per shoot). Growth ofUtricularia was similar at both sites (T ₂ 19.8–33.2 days or 9.1–16.8 days, growth of whorls 3.1 or 2.7 whorls days^?1, 1.5–2.1 or 0.8–1.4 developed branches per shoot at the former or latter site, respectively). Throughout the experiment, both species at the meso-eutrophic site allocated relatively more biomass to the production and growth of branches, than to that of new whorls. The results show thatAldrovanda, although usually considered as competitively weaker, can grow faster during the growing season peak thanUtricularia due to frequent branching and the subsequent rapid growth and separation of daughter shoots. Very rapid growth of rootless aquatic carnivorous plants in nutrient-poor habitats allows the consideration of ecophysiological adaptations that enable the plants to gain limiting mineral nutrients. These adaptations include carnivory, efficient nutrient reutilization from senescent shoots, and very high affinity for mineral nutrient uptake from water. Comparison of growth rates of rare and stenotopicA. vesiculosa and very common and eurytopicU. australis shows that differences in their rarity do not seem to be based on differences of growth rate.     

Experimental transmission of Leishmania tropica to hyraxes (Procavia capensis) by the bite of Phlebotomus arabicus

The ability of the sand fly Phlebotomus (Adlerius) arabicus to transmit Leishmania tropica was studied experimentally using hyraxes (Procavia capensis), natural reservoir hosts of the parasite. Sand flies became infected with L. tropica after feeding on a lesion of needle-inoculated hyrax. Moreover, P. arabicus fed with L. tropica promastigotes transmitted the parasite to hyraxes by bite during a second bloodmeal. Although the animals remained asymptomatic after infective sand fly bite, they were PCR positive and infectious for naive sand flies. We have thus demonstrated cyclical transmission of L. tropica by P. arabicus in hyraxes. This confirms experimentally the vectorial competence of P. (Adlerius) arabicus, and demonstrates that asymptomatic reservoir hosts are infectious to appropriate vectors.     

Site-specific mutagenesis of the histidine precursor of diphthamide in the human elongation factor-2 gene confers resistance to diphtheria toxin

Protein synthesis elongation factor 2 (EF-2) from eukaryotes contains a conserved post-translationally modified histidine residue known as diphthamide. Diphthamide is a unique site of ADP-ribosylation by diphtheria toxin (DT), which is responsible for cell killing. In this report, we describe the construction of DT-resistant HeLa cell lines by engineering the toxin-resistant form of its specific substrate, protein elongation factor-2. Using site-specific mutagenesis of the histidine precursor of diphthamide, the histidine residue of codon 715 in human EF-2 cDNA was substituted with one of four amino acid residue codons: leucine, methionine, asparagine or glutamine. Mutant EF-2s were subcloned into a pCMVexSVneo expression vector, transfected into HeLa cells, and DT-resistant cell clones were isolated. The protective effect of mutant EF-2s against cell killing by DT, after exposing all four mutant strains derived from HeLa cells to different concentrations of the toxin (5-20 ng/mL) was demonstrated by: (1) the normal morphological appearance of the cells; (2) their unaffected or slightly slower growth rates; (3) their undisturbed electrophoretic DNA profiles whose integrity was virtually preserved. Mutant cell strains showed also considerable levels of resistance to very high concentrations of DT, in that they maintained slower but consistent rates of cell growth. It was hence concluded that despite its strict conservation and unique modification, the diphthamide histidine appears not to be essential to the function of human EF-2 in protein synthesis. In addition, DT-resistant HeLa cell clones should prove valuable hosts for various DT gene-containing vectors that express the toxin intracellularly.     

Complicaciones hospitalarias en una unidad geriátrica de agudos

Introduction:

In-hospital complications frequently occur in hospitalized people over 65 worsening their clinical outcomes. There are, however, few studies on the factors associated with in-hospital complications in elderly patient care.

Objective:

To evaluate factors associated with in-hospital complications in a geriatric acute care unit in Bogotá, Colombia

Materials and methods:

We conducted an analytical, observational, retrospective study in a cohort of 1,657 patients over 65 years of age who received care in the geriatric unit of a high complexity hospital in Bogotá, Colombia. The dependent variable was in-hospital complications and the independent variables, the degree of functional dependence on admission, dementia, nutritional status, social support, comorbidity, and polypharmacy. We used Poisson’s linear regression model to identify associated variables.

Results:

The bivariate analysis showed that functional dependence (PR=2.092, p≤0.001) and malnutrition (PR=2.850, p≤0.001) were associated with a higher rate of hospital-acquired infection. In the multivariate analysis, functional dependence (PR=1.931, p=0.003) and malnutrition (PR=2.502, p=0.002) remained independent factors for in-hospital complications.

Conclusion:

In acute care centers, integral assessment at admission to identify functional dependence and malnutrition predicts in-hospital complications.     

Effect of inhibition of phenylpropanoid biosynthesison peroxidase and IAA-oxidase activities and auxin contentin alfalfa suspension cultures

The inhibition of phenylpropanoid biosynthesis by 2-aminoindan-2-phosphonic acid (AIP) in alfalfa suspension cultures (Medicago sativa L.) was associated with a marked decline in the content of cinnamic acid derivatives during the whole subculture interval. The levels of all investigated forms of phenolic acids in AIP-treated cells were lower than those of control with the exception of free phenolic acids on days 1 and 2. The dynamics of free IAA content in AIP-treated cells was similar to that of the control but its peak was significantly lower. The auxin content in AIP-treated cells on days 9 and 11 represented only 35 and 40 % of control values, respectively. AIP-treatment stimulated soluble peroxidase (EC 1.11.1.7) activity in the first 2 d after cell inoculation. Time-course of soluble IAA-oxidase activities was similar to that of soluble peroxidases (with the exception of the drop in peroxidase activity on day 3) but beginning day 6, the enzyme activities in AIP-treated cells were significantly lower until the end of the subculture interval.     

Body mass index, waist circumference and waist-to-hip ratio: which anthropometric indicator is better predictor for the hypertension development in women population of the island Cres

The aim of this research was to investigate the prevalence of obesity and high blood pressure and to prove which of three anthropometric indicators of obesity - waist circumference, body mass index (BMI) waist-to-hip ratio - is better predictor for the development of hypertension in women population of the island of Cres. We approached separately groups of women with measured high blood pressure and with previously diagnosed. The research was preformed within the research project "Genetic and biomedical characteristics of the population of the island of Cres". This was the cross sectional study and data were obtained on the sample of 247 females over 18 years old that voluntarily participated in this study. In our study group the prevalence of overweight was 39.0%, obesity 27.5%, increased waist circumference was present in 69.4% while increased blood pressure was found in 53.0% examinees. Our results indicate that age, BMI, impaired glucose concentration and serum cholesterol could be considered as predictors for the development of arterial hypertension, whether measured or previously diagnosed.