Optimal control strategies and cost-effectiveness analysis of a malaria model

The aim of this paper is to investigate the effectiveness and cost-effectiveness of three malaria preventive measures (use of treated bednets, spray of insecticides and a possible treatment of infective humans that blocks transmission to mosquitoes). For this, we consider a mathematical model for the transmission dynamics of the disease that includes these measures. We first consider the constant control parameters’ case, we calculate the basic reproduction number and investigate the existence and stability of equilibria; the model is found to exhibit backward bifurcation. We then assess the relative impact of each of the constant control parameters measures by calculating the sensitivity index of the basic reproductive number to the model's parameters. In the time-dependent constant control case, we use Pontryagin's Maximum Principle to derive necessary conditions for the optimal control of the disease. We also calculate the Infection Averted Ratio (IAR) and the Incremental Cost-Effectiveness Ratio (ICER) to investigate the cost-effectiveness of all possible combinations of the three control measures. One of our findings is that the most cost-effective strategy for malaria control, is the combination of the spray of insecticides and treatment of infective individuals. This strategy requires a 100% effort in both treatment (for 20 days) and spray of insecticides (for 57 days). In practice, this will be extremely difficult, if not impossible to achieve. The second most cost-effective strategy which consists of a 100% use of treated bednets and 87% treatment of infective individuals for 42 and 100 days, respectively, is sustainable and therefore preferable.     

Interpretation of FISH Results in the Case of Nonuniform Internal Radiation Exposure of Human Body with the Use of Model Approach

Russian Journal of Genetics - The fluorescence in situ hybridization (FISH) technique allows for the estimation of the number of stable chromosomal aberrations (translocations) in human blood...     

Isolation and Purification of Enzymes from Ligninolytic Complex of the Basidial Fungus <Emphasis Type="Italic">Trametes pubescens</Emphasis> (Schumach.) Pilat and Study of Their Properties

A method for purification of enzymes from the ligninolityc complex of the basidiomycete Trametes pubescens (Schumach.) Pilat has been elaborated. Two homogeneous isoforms of laccases (laccase 1 and laccase 2) as well as a homogeneous preparation of lignin peroxidase were isolated. Basic biochemical parameters of the enzymes were determined, such as the molecular weights (67, 67, and 45 kD, respectively), isoelectric points (5.3, 5.1, and 4.2, respectively), as well as content and composition of the carbohydrate moiety of the laccases (N-acetylglucosamine, mannose, and xylose). The pH dependences and thermal stabilities of the laccases were investigated. The kinetic parameters of the enzymatic reactions catalyzed by the laccases were determined using different substrates, such as catechol, hydroquinone, 2,2 -azinobis-(3-ethylbenzthiazoline-6-sulfonate), and K4Fe(CN)6. The structure of the active sites of both laccases and the lignin peroxidase were studied by EPR, CD, and UV-VIS spectroscopy, as well as using fluorescence analysis. Our studies showed similarity of the spectral characteristics of the two laccases, whereas their kinetic properties were found to be different.     

Stochastic modelling of axial dispersion in external-loop airlift bioreactors

The paper presents a model of the motion of a particle subjected to several transport processes in connection with mixing in two phase flow. A residence time distribution technique coupled with a one-dimensional dispersion model was used to obtain the axial dispersion coefficient in the liquid phase, D_ax. The proposed model of D_ax for an external-loop airlift bioreactor is based on the stochastic analysis of the two-phase flow in a cocurrent bubble column and modified for the specific flow in the airlift reactor. The model takes into account the riser gas superficial velocity, the riser liquid superficial velocity, the Sauter bubble diameter, the riser gas hold-up, the downcomer-to-riser cross sectional area ratio. The proposed model can be applied with an average error of ᆨ.     

The protein disulfide isomerase-like RB60 is partitioned between stroma and thylakoids in Chlamydomonas reinhardtii chloroplasts

Translation of psbA mRNA in Chlamydomonas reinhardtii chloroplasts is regulated by a redox signal(s). RB60 is a member of a protein complex that binds with high affinity to the 5'-untranslated region of psbA mRNA. RB60 has been suggested to act as a redox-sensor subunit of the protein complex regulating translation of chloroplast psbA mRNA. Surprisingly, cloning of RB60 identified high homology to the endoplasmic reticulum-localized protein disulfide isomerase, including an endoplasmic reticulum-retention signal at its carboxyl terminus. Here we show, by in vitro import studies, that the recombinant RB60 is imported into isolated chloroplasts of C. reinhardtii and pea in a transit peptide-dependent manner. Subfractionation of C. reinhardtii chloroplasts revealed that the native RB60 is partitioned between the stroma and the thylakoids. The nature of association of native RB60, and imported recombinant RB60, with thylakoids is similar and suggests that RB60 is tightly bound to thylakoids. The targeting characteristics of RB60 and the potential implications of the association of RB60 with thylakoids are discussed.     

Characteristics of Sleep–Wakefulness Cycle and Circadian Activity in the Lesser Mouse-Deer (Tragulus kanchil)

Doklady Biological Sciences - The pattern of sleep and circadian activity of the lesser mouse-deer (Tragulus kanchil) that is the smallest (body mass between 1.5 and 2.2 kg) representative of the...     

Approaches to site-directed DNA integration based on transposases and retroviral integrases

The ability of retroviruses and transposons to insert their genome into the host cell makes them attractive objects for constructing gene therapy vectors. However, enzymes that insert genetic material do not possess any selectivity relative to target nucleotide sequences, which results in almost random DNA insertion into the recipient cell genome. This leads to mutations that in turn may cause certain undesirable consequences and sometimes neoplastic cell transformation. For successful functioning, it is a primary necessity to modify a retrovirus and transposon based genetic therapy systems in such a way that the directed vector integration into a target sequence in the human genome can be achieved. In this review, the approaches to date that have been developed for highly specific modification of the genome using fusion protein construction based on retroviral integrases and transposases are discussed, as well as cellular factors interacting with these enzymes.     

In vitro dissociation-recombination of malate dehydrogenase subunits in Corydalis solida

Summary Two allelic forms of NAD specific malate dehydrogenase were found in samples of a wild population of Corydalis solida. The dimeric nature and the origin of the heterodimeric form has been demonstrated by in vitro dissociation and recombination of the subunits detected by subsequent electrophoresis. The method is applicable for polyacrylamide gel electrophoresis of crude leaf extracts of individual MDH isozyme forms.     

Nuclear DNA content of Vitis vinifera cultivars and ploidy level analyses of somatic embryo-derived plants obtained from anther culture

Flow cytometry was employed to determine the ploidy level of Vitis vinifera L. somatic embryo-derived plants obtained from anther culture. Only one among the 41 analysed plants (2.4%) presented somaclonal variation (tetraploidy); the other plants were diploid. No significant differences (P≤0.05) were detected between diploid and parental field plants. No haploid or aneuploid plants were observed. The nuclear DNA content of nine V. vinifera cultivars was also estimated using flow cytometry. A non-significant variation was found among the cultivars, with DNA content ranging from 1.17 pg/2C (cv. ‘Tinta Barroca’ and ‘Viosinho’) to 1.26 pg/2C (cv. ‘Cabernet Sauvignon’). These results and previous studies on other Vitis species suggest that Vitis genome is stable with regard to nuclear DNA content.     

Regulation of nitrogen fixation (nif) genes of Azospirillum brasilense by nifA and ntr (gln) type gene products

Abstract Eight Nif⁻ mutants of Azospirillum brasilense were obtained by N -nitrosoguanidine mutagenesis and isolated by growth on glutamate medium. Three of these mutants had no nitrogenase activity, possessed no nitrogenase structural proteins and were complemented by Klebsiella pneumoniae nifA . Evidence will be presented that one of these mutants is defective in a nifA type regulatory gene but the other two were also complemented by K. pneumoniae ntrC and may be ntrC⁻ -type mutants. A fourth mutant was defective in the MoFe component protein of nitrogenase.