Prevalence Of Gastro-Intestinal Parasites In Relation To Availability Of Sanitary Facilities Among Schooling Children In Makurdi, Nigeria

The prevalence of gastro-intestinal parasites in school children in relation to availability of sanitaryfacilities was investigated. Stool samples from 580 pupils from nine schools in Makurdi were examined for intestinal parasites. Sanitary facilties available within the schools were also noted. The overall prevalence rate of parasitic infection was 5413%. Pupils in schools that had lower ratio of number of pupils per toilet had lower infection rates than those from schools with high ratio of number of pupils per toilet. This was however not statistically sgnificant (X 22.272, d = 2, P > 0.05). The following parasites were encountered, namely Ascaris lumbricoides (11.89%), Ancylostoma duodenale (18.62 %), Strongyloides steroralis (1.89%), Trichuris trichura (4.65%), Tapeworm (3.79 %), Entamoeba histolytica (7.06 %), Schistosoma mansoni (1.55 %) and Entemoeba coli (2.41 %). The implications of these results were discussed highlighting the need for provision of sanitary facilities: lke children friendly toiets portable water and fencing the school premises from trespassers as long-term intervention strategies. Occasional activities like mass school based chemotherapy and health education are recommended as immediate interventionstrategies to prevent and control intestinal parasite Keywords: Intestinal parasites, School children, Sanitary facilitiesAnimal Research International Vol. 3 (2) 2006 pp. 489-49

Salmonella enterica biofilm-mediated dispersal by nitric oxide donors in association with cellulose nanocrystal hydrogels

Protected by extracellular polymers, microbes within biofilms are significantly more resistant to disinfectants. Current research has been instrumental in identifying nitric oxide donors and hydrogels as potential disinfectant additives. Nitric oxide (NO) donors are considered a very promising molecule as biofilm dispersal agents and hydrogels have recently attracted a lot of interest due to their biocompatible properties and ability to form stable thin films. When the NO donor MAHMA NONOate was dissolved in phosphate saline buffer, it was able to reduce the biomass of well-established biofilms up to 15% for at least 24 h of contact time. Encapsulation of MAHMA NONOate and molsidomine within a hydrogel composed of cellulose nanocrystals (CNC) has shown a synergistic effect in dispersing well-established biofilms: after 2 h of exposure, moderate but significant dispersion was measured. After 6 h of exposure, the number of cells transitioning from the biofilm to the planktonic state was up to 0.6 log higher when compared with non-treated biofilms. To further explore the transport processes of NO donors within hydrogels, we measured the nitric oxide flux from gels, at 25°C for a composite of 0.1 µM MAHMA NONOate–CNC. Nitric oxide diffuses up to 500 µm from the hydrogel surface, with flux decreasing according to Fick’s law. 60% of NO was released from the hydrogel composite during the first 23 min. These data suggest that the combined treatments with nitric oxide donor and hydrogels may allow for new sustainable cleaning strategies

Evolutionary Patterning: A Novel Approach to the Identification of Potential Drug Target Sites in Plasmodium falciparum

Malaria continues to be the most lethal protozoan disease of humans. Drug development programs exhibit a high attrition rate and parasite resistance to chemotherapeutic drugs exacerbates the problem. Strategies that limit the development of resistance and minimize host side-effects are therefore of major importance. In this study, a novel approach, termed evolutionary patterning (EP), was used to identify suitable drug target sites that would minimize the emergence of parasite resistance. EP uses the ratio of non-synonymous to synonymous substitutions (ω) to assess the patterns of evolutionary change at individual codons in a gene and to identify codons under the most intense purifying selection (ω≤0.1). The extreme evolutionary pressure to maintain these residues implies that resistance mutations are highly unlikely to develop, which makes them attractive chemotherapeutic targets. Method validation included a demonstration that none of the residues providing pyrimethamine resistance in the Plasmodium falciparum dihydrofolate reductase enzyme were under extreme purifying selection. To illustrate the EP approach, the putative P. falciparum glycerol kinase (PfGK) was used as an example. The gene was cloned and the recombinant protein was active in vitro, verifying the database annotation. Parasite and human GK gene sequences were analyzed separately as part of protozoan and metazoan clades, respectively, and key differences in the evolutionary patterns of the two molecules were identified. Potential drug target sites containing residues under extreme evolutionary constraints were selected. Structural modeling was used to evaluate the functional importance and drug accessibility of these sites, which narrowed down the number of candidates. The strategy of evolutionary patterning and refinement with structural modeling addresses the problem of targeting sites to minimize the development of drug resistance. This represents a significant advance for drug discovery programs in malaria and other infectious diseases

Balance This! Case Histories From Difficult Balance Jobs.

Tutorialpg. 193-212There are many good references for classical balance problems; however, specific ways of handling non-ideal conditions are rarely presented. Therefore, this tutorial focuses on six case histories, which illustrate actual problems that were encountered while trying to field balance different types of rotating machinery. Coupling lockup, thermal bows, eccentricity, looseness, and structural resonances can prevent successful balancing if not properly identified and corrected. This tutorial shows how these real world pitfalls can complicate balance procedures and provides some ways of dealing with these issues such as: indexing coupling parts, using inference fits, adding structural bracing, and acquiring vibration measurements at additional locations. This tutorial also gives a brief description of the common types of unbalance

Glycerol kinase from Escherichia coli and an Ala65→Thr mutant: the crystal structures reveal conformational changes with implications for allosteric regulation

AbstractBackground: Glycerol kinase (GK) from Escherichia coli is a velocity-modulated (V system) enzyme that has three allosteric effectors with independent mechanisms: fructose-1,6-bisphosphate (FBP); the phosphocarrier protein IIAGlc; and adenosine nucleotides. The enzyme exists in solution as functional dimers that associate reversibly to form tetramers. GK is a member of a superfamily of ATPases that share a common ATPase domain and are thought to undergo a large conformational change as an intrinsic step in their catalytic cycle. Members of this family include actin, hexokinase and the heat shock protein hsc70.Results: We report here the crystal structures of GK and a mutant of GK (Ala65→Thr) in complex with glycerol and ADP. Crystals of both enzymes contain the same 222 symmetric tetramer. The functional dimer is identical to that described previously for the IIAGlc–GK complex structure. The tetramer interface is significantly different, however, with a relative 22.3° rotation and 6.34 å translation of one functional dimer. The overall monomer structure is unchanged except for two regions: the IIAGlc-binding site undergoes a structural rearrangement and residues 230–236 become ordered and bind orthophosphate at the tetramer interface. We also report the structure of a second mutant of GK (IIe474→Asp) in complex with IIAGlc; this complex crystallized isomorphously to the wild type IIAGlc–GK complex. Site-directed mutants of GK with substitutions at the IIAGlc-binding site show significantly altered kinetic and regulatory properties, suggesting that the conformation of the binding site is linked to the regulation of activity.Conclusions: We conclude that the new tetramer structure presented here is an inactive form of the physiologically relevant tetramer. The structure and location of the orthophosphate-binding site is consistent with it being part of the FBP-binding site. Mutational analysis and the structure of the IIAGlc–GK(IIe474→Asp) complex suggest the conformational transition of the IIAGlc-binding site to be an essential aspect of IIAGlc regulation