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Biomedical subjects

A Adams

Publications and source records attributed to A Adams.

At least 19 recordsLinked to original sources
PubMed2007

Sacculogenesis and sporogony of Tetracapsuloides bryosalmonae (Myxozoa: Malacosporea) within the bryozoan host Fredericella sultana (Bryozoa: Phylactolaemata).

Tetracapsuloides bryosalmonae is the myxozoan parasite responsible for proliferative kidney disease (PKD) of salmonid fishes. This disease affects farmed species in North America and Western Europe where it results in significant economic losses for the rainbow trout industry. The parasite has two hosts in its life cycle, salmonid fish, and freshwater bryozoans. In this study, we describe the development of the parasite at the ultrastructural level within the bryozoan host Fredericella sultana. Single celled, presaccular stages form aggregates within the metacoel of this host which resolve into spore sacs. Within these sacs sporogenesis is initiated with the differentiation of presporogonic cells into sporogonic and valvogenic cells. These latter cells surround a sporogonic cell which subsequently divides to form a sporoplasmogenic cell and a capsulogenic cell. The capsulogenic cell divides further to form four cells each with a polar capsule, while the sporoplasmogenic cell divides resulting in four cells, two primary cells and two secondary cells. The secondary cells are engulfed by the primary cells resulting in a mature sporoplasm. It is hypothesized that autogamy occurs during the initial formation of the spore sac and that allogamy is also possible during this time.

Animals↗
PubMed2006

Transmission of Tetracapsuloides bryosalmonae (Myxozoa: Malacosporea), the causative organism of salmonid proliferative kidney disease, to the freshwater bryozoan Fredericella sultana.

Proliferative kidney disease (PKD), caused by the malacosporean parasite Tetracapsuloides bryosalmonae, causes significant losses among salmonids in Western Europe and North America. The role of salmonid fish in the life-cycle of this parasite has been conjectured upon for over a quarter of a century. To examine whether fish can transmit the infection to bryozoans, the known invertebrate host, water containing parasitized brown trout Salmo trutta was pumped into tanks containing colonies of Fredericella sultana collected from the wild. The specific parasite-free status of these colonies being first assessed, by PCR and prolonged laboratory culture. After 6 weeks exposure to the brown trout aquarium effluent, portions of these colonies displayed overt infections with T. bryosalmonae. This was in contrast to control bryozoans, derived from the experimental colonies prior to exposure, which remained T. bryosalmonae negative. In addition, spores obtained from the experimentally infected colonies were exposed to naïve rainbow trout, resulting in clinical PKD, thus completing a cycle of transmission. During the experiments, the infection was noted to inhibit statoblast formation within bryozoans and appeared to be pathogenic, finally killing the bryozoan host. These findings indicate that fish can transmit the parasite to bryozoans and are an integral part of this parasite's life-cycle.

Animals↗
PubMed2006

Immunostaining of spores and plasmodia of disparate myxozoan genera with comments on the properties of the sporular mucus envelope.

Species of the phylum Myxozoa are common parasites of fish and can cause severe losses in cultured species. Although a number of myxozoan life-cycles have now been elucidated, little is known about the biology of these organisms in the fish host. Monoclonal antibody B4 raised to the myxozoan Tetracapsuloides bryosalmonae has been previously noted to react with a number of species infecting fish kidney. We present the results of a survey of 55 myxosporean species that determined that this antibody detects an antigen on the spore surface of 33 of these species in the genera Myxobolus, Sphaerospora and Thelohanellus. However, there appears to be no clear relationship between those spores that contain the MAb B4 reactive antigen and the host or organ in which they are detected. The antigen appears to be synthesized in the plasmodial cytoplasm and is intimately associated with the surface of the spore capsules and, where present, the mucus envelope. The nature of this envelope is further discussed in relation to its formation and distinctive properties.

Animals↗
PubMed2006

Improved purification of Piscirickettsia salmonis using Percoll gradients.

Viable preparations of intact Piscirickettsia salmonis, purified from host cell material, are necessary for studying characteristics associated with this bacterium. However, purification of the organism is difficult due to its obligate intracellular nature. A simple and effective method for isolating whole P. salmonis, which is quick and easy to perform, but still maintains the viability and antigenicity of the bacterium is described. P. salmonis was purified by differential pelleting and density gradient centrifugation using 30%, 40%, or 50% (v/v) Percoll gradients. Following fractionation, a band with a density of 1.056-1.080 was found to be composed entirely of rickettsiae, confirmed by fluorescent antibody technique (IFAT). Purity of the P. salmonis from different stages of the purification process was assessed by light and transmission electron microscopy, and the viability of yields determined from a plaque assay and a tissue culture infective dose (TCID(50) ml(-1)). P. salmonis recovered from the 30% Percoll gradient appeared to retain their intracellular structure better than P. salmonis obtained from the 40% and 50% Percoll gradients, and appeared to have a greater viability. Differences were seen between P. salmonis-infected CHSE-214 cells and purified P. salmonis when compared by SDS-PAGE and Western blotting, and less host cell contamination was present in preparations obtained from the 30% Percoll gradient. Finally ten different P. salmonis isolates obtained from three different geographical locations and four different fish species, were purified using the 30% Percoll gradient. When the morphology of these was compared by transmission electron microscopy (TEM), they appeared similar in size and appearance, although isolate R980769 was highly pleomorphic and isolate R-29 was larger than the other isolates examined.

Animals↗
PubMed2006

Development of a liquid chromatography/tandem mass spectrometry method for the simultaneous determination of 16 mycotoxins on cellulose filters and in fungal cultures.

The development of a liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for the simultaneous determination of 16 mycotoxins possibly related to the 'Sick Building Syndrome' on filters and in fungal cultures is described. Fungi-surface sampling as regards the 'Sick Building Syndrome' preferably happens by scraping off fungal material and vacuuming onto cellulose filters. Therefore, these two media were used as samples. They were spiked with nivalenol, deoxynivalenol, zearalenone, diacetoxyscirpenol, T-2 toxin, verrucarol, verrucarin A, neosolaniol, sterigmatocystin, roridin A, ochratoxin A, aflatoxin B1, aflatoxin B2, aflatoxin G1 and aflatoxin G2, which can be produced by isolates from fungi-damaged buildings. Deepoxy-deoxynivalenol was used as internal standard. Samples were extracted with organic solvents and the different mycotoxins were separated by high-performance liquid chromatography (HPLC) using a C18 reversed-phase SunFire analytical column and a mobile phase of variable mixtures of ammonium acetate (10 mM) and sodium acetate (20 microM) in water (solvent A) and in methanol (solvent B). The samples were run on-line with a Micromass Quattro Micro triple quadrupole mass spectrometer in positive electrospray ionisation mode using multiple reaction monitoring (MRM). The detection limits of the procedure varied from 50 to 0.009 pg/microL for filter samples and from 75 to 0.04 pg/microL for fungal culture samples. As the method includes few and non-labourious sample treatment steps, it should allow for a high throughput of samples.

Biomass↗
PubMed2006

A new look at blockade of T-cell costimulation: a therapeutic strategy for long-term maintenance immunosuppression.

Activated T cells orchestrate the immune response that results in graft rejection; therefore, a common goal among current immunosuppressive therapies is to block T-cell activation, proliferation and function. Current immunosuppressive regimens that inhibit T cells and immune cells have greatly reduced the incidence of acute rejection following solid-organ transplant. However, the expected improvements in long-term outcomes have not been realized. This may be related to the non-immune side effects of current maintenance immunosuppressants, which target ubiquitously expressed molecules. The focus in transplantation research is shifting in search of maintenance immunosuppressive regimens that might offer improved long-term outcomes by providing efficacy in prevention of acute rejection combined with reduced toxicities. An emerging therapeutic strategy involves an immunoselective maintenance immunosuppressant that inhibits full T-cell activation by blocking the interaction between costimulatory receptor-ligand pairs. This review describes costimulatory pathways and the development of molecules, which inhibit them in the context of transplantation research. Recent clinical data using the selective costimulation blocker, belatacept (LEA29Y), as a part of a CNI-free maintenance immunosuppressive regimen in renal transplantation is highlighted.

Abatacept↗
PubMed2005

Transmission of freshwater myxozoans during the asexual propagation of invertebrate hosts.

The phylum Myxozoa contains over 1350 species almost all of which are considered to be obligate parasites of aquatic animals. The phylum is composed of two classes, the Myxosporea and the Malacosporea, species of which are important pathogens responsible for severe economic losses in cultured fisheries. The life cycles of freshwater Myxozoa are believed to involve horizontal, indirect transmission, involving an invertebrate (oligochaetes or bryozoans) and a vertebrate host (fish or amphibians). Here, we describe myxozoan propagation through the fragmentation of invertebrate hosts to form new infected individuals. The two hosts examined are an oligochaete Lumbriculus variegatus infected with an unidentified myxosporean (Triactinomyxon sp.) and the bryozoan Fredericella sultana infected with the malacosporean Tetracapsuloides bryosalmonae which causes proliferative kidney disease, a major constraint of the European rainbow trout industry. Such intra-clonal propagation is a novel form of vertical transmission that is likely to be widespread within the Myxozoa and could form an important method by which some of these parasites maintain and proliferate within the aquatic environment.

Animals↗
PubMed2005

Severe, chronic proliferative kidney disease (PKD) induced in rainbow trout Oncorhynchus mykiss held at a constant 18 degrees C.

Proliferative kidney disease (PKD), caused by the myxozoan parasite Tetracapsuloides bryosalmonae, is well documented as a seasonal disease of rainbow trout Oncorhynchus mykiss. Water temperatures influence the course of the infection both within the fish and the invertebrate host, the recovery of fish from the disease being accelerated with decreasing water temperatures. During this study, groups of rainbow trout were held at a constant temperature (18 degrees C) for a sustained period of time following initial exposure to T. bryosalmonae. While the majority of these fish had recovered from the clinical disease after 9 mo, 10% remained infected, showing clinical signs of disease. A histological study revealed that the majority exhibited very high parasite loads and unusually severe symptoms of PKD. This demonstrates that while most rainbow trout can recover from PKD independent of water temperature, there exists a sub-population that cannot.

Animals↗
PubMed2005

Confirmation of Piscirickettsia salmonis as a pathogen in European sea bass Dicentrarchus labrax and phylogenetic comparison with salmonid strains.

European sea bass Dicentrarchus labrax from the Mediterranean were diagnosed with a severe encephalitis. Rickettsia-like organisms (RLOs) were associated with brain lesions in routine paraffin sections. These were found to share common antigens with the Piscirickettsia salmonis type-strain, LF-89, by indirect fluorescent antibody test (IFAT) and by immunohistochemistry (IHC). In addition, we compared the DNA sequences of the 16S rDNA and 16S-23S internal transcribed spacer region (ITS) with those published for P. salmonis strains and found that the sea bass piscirickettsia-like organism (SBPLO) was another strain of P. salmonis, closely related to the salmonid pathogens. Furthermore, we showed that the SBPLO possessed at least 2 ITS regions, 1 of which contained tRNA genes.

Animals↗
PubMed2005

Ultrastructural and molecular characterization of Bacillidium vesiculoformis n. sp. (Microspora: Mrazekiidae) in the freshwater oligochaete Nais simplex (Oligochaeta: Naididae).

The development of a new species, Bacillidium vesiculoformis n. sp. (Microspora, Mrazekiidae), is described from the freshwater oligochaete Nais simplex (Oligochaeta, Naididae). Initial stages of parasite development consist of a monokaryotic merogony within a haemocyte of the intestinal blood sinus. The resulting hypertrophied haemocyte is attached to the chloragocytes of the sinus by fine cytoplasmic extensions with the sinus around the cell becoming greatly enlarged. The meronts within the haemocyte form diplokaryotic sporonts that undergo sporogenesis directly within the cytoplasm of the host cell. The infected cell becomes packed with spores and developmental stages, causing it dramatically to increase in size, eventually rupturing the oligochaete and cell. Sporogony appears to be disporoblastic. Released spores were observed to have an adhesive quality. Transmission studies conducted with mature spores failed to transmit the parasite horizontally although vertical transmission was observed. Phylogenetic analysis of the parasite demonstrated that B. vesiculoformis clustered with microsporidian parasites of bryozoa and two other microsporidians, Janacekia debaiseuxi and an unidentified Bacillidium sp.

Animals↗
PubMed2005

What gets missed when deploying new technologies in A&E?

This paper presents a longitudinal study (over 4 months) of an A&E department where the existing whiteboards were replaced with PC-based computer systems. The study was conducted in two parts - an observation of the physical whiteboard usage and in-depth interviews with all users of both the traditional whiteboard usage and the replacement technology. The research was conducted with the systems manager and all whiteboard users (i.e. nursing management, nurses, doctors, porters, and agency staff) across a spread of time frames. Although the technology supported simple information requirements, complex co-ordination, collaboration, and awareness issues were left unsupported. The important role of a pen-holder (information co-ordinator) was poorly supported by the replacement technology as was the task of annotating information with changing situations and needs. Specific deployment issues are derived from these findings that should guide designers when implementing technology replacements for current physical information formats (e.g. whiteboards, notice boards, shared paper notes).

Diffusion of Innovation↗
PubMed2004

Localization of carbohydrate terminals on Tetracapsuloides bryosalmonae using lectin histochemistry and immunogold electron microscopy.

Tetracapsuloides bryosalmonae is the myxozoan parasite that causes the commercially important proliferative kidney disease (PKD) in salmonid aquaculture. Previous studies on the binding of lectins to T. bryosalmonae identified Griffonia simplificola agglutinin I (GS I) as useful for parasite identification. This lectin was also implicated as recognizing antigenic structures on the parasite. Here, we examine the histochemical staining and ultrastructural localization of a panel of 21 lectins on the extrasporogonic stage of T. bryosalmonae. The histochemical staining studies indicated that the majority of lectins bound to the renal stages of T. bryosalmonae, however not all of these lectins could be successfully localized using immunogold electron microscopy. Of the lectins that were localized many, including GS I, bound to membranes associated with the lysosomal pathway within the extrasporogonic primary cell of the parasite, indicating that these organelles are rich in glycoconjugates. The histochemical staining of Erythrina cristagalli ECL was unique and highlighted a different distribution of glycoconjugates in the periphery of some extrasporogonic parasites within the renal sinuses when compared with stages in the interstitium, suggesting the presence of distinct blood forms of T. bryosalmonae.

Animals↗
PubMed2004

The effect of in vivo growth on the cellular and extracellular components of the marine bacterial pathogen Photobacterium damsela subsp. piscicida.

Photobacterium damsela subsp. piscicida, the causative agent of fish pasteurellosis, was grown in vivo. Bacterial cells and extracellular products (ECPs) were analysed via electrophoresis and immunoblot analysis, using specific sea bass antisera. Growth in vivo induced the synthesis of unique bacterial cell proteins at > 206, 206, 21.3, 18, 7.6 and < 7.6 kDa. Sea bass serum raised against live bacterial cells of the pathogen and especially a sea bass serum raised against formalin-inactivated bacterial cells grown in a specific novel medium recognized the novel antigens at > 206 (associated with iron sequestration), 21.3, 7.6 and < 7.6 kDa, suggesting that the latter medium conserves the synthesis of natural bacterial cell proteins in vitro. In vivo growth of the pathogen induced the synthesis of more toxic ECPs in comparison with in vitro growth and an inverse correlation between total protein concentration in the ECPs and toxicity per unit of protein was observed. Substrate-polyacrylamide electrophoresis revealed the presence of in vivo synthesized ECPs of the pathogen (proteases) at 175, 132, < 79 and 48.3 kDa. Histological examination of tissues isolated from fish injected with these ECPs revealed inflammatory and necrotic lesions in the spleen, liver, head kidney, intestine and heart as soon as 48 h post-introduction of the ECPs.

Animals↗
PubMed2003

Comparison of chemical treatments on the chain dynamics and thermal stability of bovine pericardium collagen.

A new approach for the replacement of heart valves consists of obtaining an acellular matrix from animal aortic valves that performs mechanically, is nonantigenic, and is free from calcification and fibroblast proliferation. Novel biochemical treatments must be developed for this purpose. In this work, we focus on the characterization of collagen in acellular bovine cardiovascular tissues, fresh or glutaraldehyde treated, and stored in different solutions [phosphate-buffered saline (PBS), ethanol, octanol, and glutaraldehyde], to determine whether the resulting fibrous material is structurally preserved. The preservation of the triple helical structure of collagen is checked by differential scanning calorimetry (DSC), which is a well suited technique to analyze thermal transitions in proteins, such as denaturation. To get insight into the molecular dynamics of collagen in the nanometric range, we used thermally stimulated currents, a dielectric technique running at low frequency, that measure the dipolar reorientations in proteins submitted to a static electrical field. The combined use of these two techniques allowed us to evaluate the physical structure and conformation of collagen after the different chemical treatments. We have found that the glutaraldehyde treatment followed by octanol storage preserves the triple helical conformation of the polypeptidic chains of collagen, contrary to the ethanol and PBS storage that induce drastic changes in the thermal and dielectric behavior of the protein. Moreover, this particular chemical treatment stabilizes the collagen structure (shift toward high temperature of the collagen denaturation and stiffening of the chains by a cross-linking action) when compared to the control sample, and so could provide interesting fibrous material for the conception of bioprosthetic heart valve.

Animals↗