Fasciola gigantica: surface topography of the adult tegument

Adult Fasciola gigantica are leaf-shaped with tapered anterior and posterior ends and measure about 35 mm in length and 15 mm in width across the mid section. Under the scanning electron microscope its surface appears rough due to the presence of numerous spines and surface foldings. Both oral and ventral suckers have thick rims covered with transverse folds and appear spineless. On the anterior part of the ventral surface of the body, the spines are small and closely-spaced. Each spine has a serrated edge with 16 to 20 sharp points, and measures about 20 microm in width and 30 microm in height. In the mid-region the spines increase in size (up to 54 microm in width and 58 microm in height) and number, especially towards the lateral aspect of the body. Towards the posterior end the spines progressively decrease in both size and number. The tegumental surface between the spines appears highly corrugated with transverse folds alternating with grooves. At higher magnifications the surface of each fold is further increased with a meshwork of small ridges separated by variable-sized pits or slits. There are three types of sensory papillae on the surface. Types 1 and 2 are bulbous, measuring 4-6 microm in diameter at the base with nipple-like tips, and the type 2 also have short cilia. Type 3 papillae are also bulbous and of similar size but with a smooth surface. These sensory papillae usually occur in clusters, each having between 2 and 15 units depending on the region of the body. Clusters of papillae on the lateral aspect (usually types 1 and 2) and around the suckers (type 3) tend to be more numerous and larger in size. The dorsal side of the body exhibits similar surface features, but the spines and papillae appear less numerous and are smaller. Corrugation and invaginations of the surface are also less extensive than on the ventral side of the body.     

Hydrogen peroxide as a supplemental oxygen source for activated sludge: Microbiological investigations

Summary Parallel bench-scale activated sludge systems were operated using air or hydrogen peroxide as oxygen source. The use of H₂O₂ resulted in a temporary decrease of COD reduction, an increase of the catalase activity of the activated sludge, a depression of the nitrification, and a marked decrease of some filamentous organisms. Enumeration of some microbiologic groups indicated that the counts of enterobacteria, coliforms, staphylococci, and streptococci were lower in the H₂O₂ unit than in the parallel air unit. Also the use of H₂O₂ did not induce the selection of bacterial species that are more resistant to H₂O₂. The increase in catalase activity after H₂O₂ addition might be the result of a stimulation of catalase synthesis in catalase positive microorganisms.List of Abbreviation COD chemical oxygen demand, mg O₂/1 - COD_eff chemical oxygen demand of the effluent, mg O₂/1 - DO dissolved oxygen, mg O₂/1 - MLSS mixed liquor suspended solids, g dry weight/1 - SVI sludge volume index, ml settled sludge per liter/MLSS (ml/g) - F:M sludge loading factor or the Food to Microorganisms ratio, g COD/g MLSS.day     

The use of activated carbon for the removal of pharmaceuticals from aqueous solutions: a review

The presence of pharmaceutically active compounds in surface and ground water is of concern due to the adverse effects they may have on human health, aquatic life, and the environment, emphasizing the importance of their removal from the water compartment. Activated carbon adsorption has proven to be effective for the removal of several types of inorganic and organic contaminants either as a stand-alone polishing step or in combination with other conventional and advanced water and wastewater treatment systems. This paper discusses the current status of the removal of pharmaceuticals from water using activated carbon derived from numerous precursors, providing an in-depth review of the multitude of factors (adsorbent properties, adsorbate properties, operating conditions) affecting the adsorption process, from the preparation of the activated carbon to its regeneration. A critical assessment of the existing literature is presented, highlighting research and development needs that may ultimately lead to a more comprehensive and sustainable use of activated carbon for the removal of pharmaceuticals from the water environment.     

Structural complexity in mussel beds: the fractal geometry of surface topography

Seafloor topographic complexity is ecologically important because it provides habitat structure and alters boundary-layer flow over the bottom. Despite its importance, there is little agreement on how to define and measure surface complexity. The purpose of this investigation was to utilize fractal geometry of vertical cross-section profiles to characterize the surface topography of the soft-bottom mussel bed (Mytilus edulis L.) at Bob's Cove, ME, USA. Mussels there have been shown previously to have spatially ordered fractal characteristics in the horizontal plane. Two hypotheses were tested. The first was that the bed surface is fractal over the spatial scale of 1.44-200 mm, with fractal dimension less than or equal to 1.26, the value for the Koch curve, our model for bed profiles. The second was that bed surface topography (i.e., in vertical profile) is less complex than the mussel bed spatial pattern (i.e., aerial view in the horizontal plane). Both hypotheses were supported. Cross-sections of plaster casts of the bed produced 88 surface profiles, all of which were fractal over the entire spatial scale of more two orders of magnitude employed in the analysis. Fractal dimension values (D) for individual profiles ranged from 1.031 to 1.310. Fractal dimensions of entire casts ranged up to mean (1.242+/-0.046) and median (1.251) values similar to 1.26, the theoretical value of the Koch curve. The bed surface was less complex than the bed spatial pattern because every profile had D<1.36, the smallest value previously obtained from aerial views of the bed. The investigation demonstrated for the first time that surface topography of a soft-bottom mussel bed was fractal at a spatial scale relevant to hydrodynamic processes and habitat structure important for benthic organisms. The technique of using cross-section profiles from casts of the bed surface avoided possible underestimates of fractal dimension that can result from other profiling methods reported in the literature. The results demonstrate that fractal dimension can be useful in the analysis of habitat space and water flow over any irregular seafloor surface because it incorporates the size, shape, and scale of roughness elements into a simple, numerical metric.     

Comparative study of the phenylalanyl-tRNA synthetases from Escherichia coli and Thermus thermophlus by the tritium topography method

A comparative study of thermostability and aminoacid composition of the phenylalanyl-tRNA synthetases from E. coli and Thermus thermophilus HB8 has been carried out. Compared with the mesophilic enzyme, a considerable increase of Pro, Leu, Phe, Arg and decrease of Asx, Ile, Ser, Thr and Lys content have been revealed in the thermophilic protein. Using tritium topography, Pro, (Leu + Ile) and Gly were found to be the most accessible on the surfaces of both the enzymes. In the E. coli enzyme, Thr residues were also easy to access while on the surface of the thermophilic enzyme there were more Arg residues. The quantitative assay of the surface compositions revealed the increased exposure of the (Leu + Ile) residues on the thermophilic protein as well as of the charged Asx and Arg residues. A possible correlation of the observed effects with thermostability is discussed.     

The influence of cartilage surface topography on fluid flow in the intra-articular gap

Self-lubrication of a diarthrodial joint is largely attributed to interstitial fluid pressurisation. However, the retention of synovial fluid within the intra-articular gap may also contribute to lubrication. Fluid flow in the intra-articular gap between two micro-rough cartilage surfaces was simulated with a three-dimensional numerical model. Representative surface roughness parameters were incorporated and their relative influence on gap flow resistance was quantified. Resistance changes with decreasing gap height were explored. Cartilage surface micro-topography improves the retention of viscous synovial fluid in the gap, through increased resistance to tangential flow. Local asperity contact greatly increases resistance through tortuosity of the flow path.     

The reactivity of functional groups as a probe for investigating the topography of tobacco mosaic virus. The use of mutants with additional lysine residues in the coat protein

Several mutants of tobacco mosaic virus that contain additional lysine residues as a result of mutations in the coat protein were investigated. Mutant E66 has a lysine residue replacing asparagine at position 140 when compared with the wild-type vulgare and this lysine residue reacts readily in the intact virus with methyl picolinimidate. Mutant B13a has two new lysine residues in the coat protein, replacing a glutamine at position 9 and an asparagine at position 33, whereas mutant B13b has the single replacement of glutamine by lysine at position 9. The lysine residue at position 9 in mutants B13a and B13b also reacts readily with methyl picolinimidate in the intact virus but the lysine at position 33 in mutant B13a did not react under these conditions. However, when the isolated coat protein from mutant B13a was treated with methyl picolinimidate, the lysine residue at position 33 did become modified, showing that the loss in reactivity of this residue towards the imidoester in the intact virus is a result of the assembly of the protein subunit into the virus structure. These results are compatible with and extend previous studies on the sero-logical properties of mutants of tobacco mosaic virus and illustrate the value of methyl picolinimidate as a reagent for probing the accessibility of amino groups in proteins. When intact tobacco mosaic virus (vulgare) was treated with p-iodobenzenesulphonyl chloride, no reaction with the lysine residues at positions 33 or 68 in the virus subunit could be detected but complete modification of tyrosine-139 was achieved. This result also extends previous studies with other reagents. The usefulness of the differential reactivity of the lysine residues in tobacco mosaic virus and its mutants as a means of attaching heavy-atom labels at chemically defined positions for subsequent X-ray-diffraction analysis and the implications of these experiments for deciphering the folding of the peptide chain in the virus subunit are discussed.     

A comparative study of phenylalanyl-tRNA synthetases from Escherichia coli and Thermus thermophilus by the tritium topography method

A comparative study of thermostability and amino acid composition of phenylalanyl-tRNA synthetases from E. coli and Thermus thermophilus HB8 has been carried out. In the thermophilic protein the proline, leucine, phenylalanine, arginine content was considerably increased, whereas that of asparagine, isoleucine, serine, threonine and lysine was decreased as compared to the mesophilic protein. Using tritium topography, Pro, (Leu + Ile) and Gly were found to be the most accessible on the surfaces of the both enzymes. In the E. coli enzyme the threonine residues were also easy to access, while on the surface of the thermophilic enzyme arginine residues were more abundant. A quantitative assay of the surface compositions revealed the increased exposure of (Leu + Ile) residues in the thermophilic protein as well as of the charged asparagine and arginine residues. A possible relationship of the observed effects to thermostability is discussed.     

The use of the radial hemolysis reaction for demonstrating antibodies to the surface antigens of the influenza virus in assessing postvaccinal immunity

Two serological tests--single radial hemolysis (RSH) and hemagglutination inhibition (HI) were used to evaluate the different techniques (intranasal, intradermal and combined methods) of application of inactivated influenza vaccines. When seroconversion to hemagglutinin (HA) was determined sensitivity of SRH proved to be higher as compared with HI by 6.7-41.4%. This test has also shown that the frequency of the seroconversion to HA was 2.1-5.6 times higher than that to neuraminidase (NA). It is important to standardize both HA and NA components in the influenza vaccine. It is interesting to study the local and cell immunity after intranasal inoculation of influenza vaccine because of the low postvaccinal level of serum antibodies and in connection with some publications concerning the protective role of this immunization method.     

The effect of combined hypergravity and micro-grooved surface topography on the behaviour of fibroblasts

This study evaluated in vitro the differences in morphological behaviour between fibroblast cultured on smooth and micro-grooved substrata (groove depth: 1 mum, width: 1, 2, 5, 10 microm), which undergo artificial hypergravity by centrifugation (10, 24 and 50 g; or 1 g control). The aim of the study was to clarify which of these parameters was more important to determine cell behaviour. Morphological characteristics were investigated using scanning electron microscopy and fluorescence microscopy in order to obtain qualitative information on cell spreading and alignment. Confocal laser scanning microscopy visualised distribution of actin filaments and vinculin anchoring points through immunostaining. Finally, expression of collagen type I, fibronectin, and alpha(1)- and beta(1)-integrin were investigated by PCR. Microscopy and image analysis showed that the fibroblasts aligned along the groove direction on all textured surfaces. On the smooth substrata (control), cells spread out in a random fashion. The alignment of cells cultured on grooved surfaces increased with higher g-forces until a peak value at 25 g. An ANOVA was performed on the data, for all main parameters: topography, gravity force, and time. In this analysis, all parameters proved significant. In addition, most gene levels were reduced by hypergravity. Still, collagen type 1 and fibronectin are seemingly unaffected by time or force. From our data it is concluded that the fibroblasts primarily adjust their shape according to morphological environmental cues like substratum surface whilst a secondary, but significant, role is played by hypergravity forces.     

The use of activated charcoal for the removal of PCR inhibitors from oyster samples

Activated charcoal is a carbonaceous adsorbent with a high internal porosity, and hence a large internal surface area. Cells of a strain of Escherichia coli O157:H7 seeded into oyster tissue homogenates were completely bound to untreated charcoal after an incubation period of 15 min at room temperature. In contrast, activated charcoal particles coated with cells of Pseudomonas fluorescens resulted in 92.6%+/-3.7 recovery of E. coli O157:H7. This allowed the successful use of the coated activated charcoal for the absorption of PCR inhibitors from seeded tissue samples. With coated charcoal, real-time PCR was able to detect 1x10(3) CFU of E. coli 0157:H7/g of tissue which was equivalent to 50 genomic targets per real-time PCR. In contrast, without the use of treated charcoal, the real-time PCR failed to detect 10(7) CFU/g. This is a promising, and convenient technology that can be applied to increase the sensitivity of the PCR assay without selective enrichment, for the detection of low numbers of pathogenic microorganisms in complex matrices such as foods, clinical, and environmental samples, which frequently exhibit high levels of PCR inhibition.     

The use of vaccinia virus for the construction of recombinant vaccines

Recombinant DNA technology has been used to engineer vaccinia virus genetically into a eukaryotic expression vector. An exciting outcome of these gene-splicing techniques is that after the insertion of one or more genes which encode the information for antigens responsible for conferring immunity toward an infectious disease, vaccinia can be adapted for the development of live recombinant vaccines. This review discusses recombinant vaccinia design and the feasibility of using these vaccines for disease protection.     

Kinesiological research: The use of surface electromyography for assessing the effects of spinal manipulation

Decreasing an elevated muscle tone is an often cited benefit of spinal manipulation. Spinal manipulation is theorized to disrupt an assumed pain-spasm-pain cycle that sufferers of low back pain may be experiencing. The current research has mostly investigated the short term influence of a single spinal manipulation on paraspinal muscle activity either at rest (e.g. standing or prone) or during simple movements (e.g. forward bend). The higher quality experiments to date have typically reported both reductions in muscle activity during lying prone or during the fully flexed position of forward bend. The only study measuring the long term influence of spinal manipulation has failed to document any change in muscle activity as measured with surface electromyography. Both manually delivered manipulations and manipulations delivered via a mechanical adjusting device have been associated with changes in muscle activation. Changes in muscle activity at muscles distant from the spinal joints manipulated (e.g. muscles in the upper limbs) have been documented following a single spinal manipulation however rather than the typical reduction in muscle activity an increase in resting activation has been reported. The state of muscle dysfunction (e.g. palpably tender or subjectively taut) may be a factor in achieving a myoelectric response to spinal manipulation. Currently, the clinical significance of short term changes in electromyographic amplitude following manipulation is unknown.     

Hemoglobin C modulates the surface topography of Plasmodium falciparum-infected erythrocytes

There is a well-established clinical association between hemoglobin genotype and innate protection against Plasmodium falciparum malaria. In contrast to normal hemoglobin A, mutant hemoglobin C is associated with substantial reductions in the risk of severe malaria in both heterozygous AC and homozygous CC individuals. Irrespective of hemoglobin genotype, parasites may induce knob-like projections on the erythrocyte surface. The knobs play a major role in the pathogenesis of severe malaria by serving as points of adherence for P. falciparum-infected erythrocytes to microvascular endothelia. To evaluate the influence of hemoglobin genotype on knob formation, we used a combination of atomic force and light microscopy for concomitant topographic and wide-field fluorescence imaging. Parasitized AA, AC, and CC erythrocytes showed a population of knobs with a mean width of approximately 70 nm. Parasitized AC and CC erythrocytes showed a second population of large knobs with a mean width of approximately 120 nm. Furthermore, spatial knob distribution analyses demonstrated that knobs on AC and CC erythrocytes were more aggregated than on AA erythrocytes. These data support a model in which large knobs and their aggregates are promoted by hemoglobin C, reducing the adherence of parasitized erythrocytes in the microvasculature and ameliorating the severity of a malaria infection.     

The effect of combined simulated microgravity and microgrooved surface topography on fibroblasts

This study evaluated in vitro the differences in morphological behaviour between fibroblast cultured on smooth and microgrooved substrata (groove depth: 0.5 microm, width: 1, 2, 5, and 10 microm), which were subjected to simulated microgravity. The aim of the study was to clarify which of these parameters was more dominant to determine cell behaviour. Morphological characteristics were investigated using scanning electron microscopy and fluorescence microscopy in order to obtain qualitative information on cell alignment and area. Confocal laser scanning microscopy visualised distribution of actin filaments and focal adhesion points. Finally, expression of collagen type I, fibronectin, and alpha1- and beta1-integrin were investigated by PCR. Microscopy and image analysis showed that the fibroblasts aligned along the groove direction on all textured surfaces. On the smooth substrata, cells had spread out in a random fashion. The alignment of cells cultured on grooved surfaces decreased under simulated microgravity, especially after 24 h of culturing. Cell surface area on grooved substrata were significantly smaller than on smooth substrata, but simulated microgravity on the grooved groups resulted in an enlargement of cell area. ANOVA was performed on all main parameters: topography, gravity force, and time. In this analysis, all parameters proved significant. In addition, gene levels were reduced by microgravity particularly those of beta1-integrin and fibronectin. From our data it is concluded that the fibroblasts primarily adjust their shape according to morphological environmental cues like substratum surface whilst a secondary, but significant, role is played by microgravity conditions.