Biomedical subjects

S Chinabut

Publications and source records attributed to S Chinabut.

5 recordsLinked to original sources

PubMed2006

Problems associated with shellfish farming.

Shellfish culture is a major sector of aquaculture production worldwide, and zoonoses and drug residues associated with shellfish farm practice are of concern to public health. This paper focuses on three of the most important shellfish species: molluscs, crabs and shrimp. Although many diseases can affect shellfish, they do not appear to be transmittable to humans. Rather, the main hazards are associated with the methods used to farm the different species. The risk to human health from shellfish most commonly relates to contamination by biotoxins produced by marine algae. Another well-recognised problem associated with shellfish culture is the contamination of shellfish with domestic sewage that contains human pathogenic bacteria and viruses, which causes diseases such as typhoid fever and hepatitis. In shrimp farming, the main potential food safety hazards are zoonoses, chemical contamination and veterinary drug residues. Untreated effluent from shrimp farms is a major concern to the environmental sector as it is known to promote plankton blooms if directly discharged into natural water sources.

Animals↗

PubMed2005

The choice of disease control strategies to secure international market access for aquaculture products.

Since production from capture fisheries cannot meet the demands of exports, aquaculture has subsequently played a major role in securing the raw materials for the world's food industries. Aquaculture has rapidly developed from extensive systems to semi-intensive, intensive and super-intensive systems. This has introduced the use of chemicals and drugs into the systems, which cause residual problems in the products. In the developed world, food safety has become a major issue of concern. The world market now demands healthy aquaculture products from farm to table. To achieve these requirements and to keep their markets, countries involved in aquaculture have implemented control measures such as farm licensing, code of conduct for sustainable aquaculture, hazard analysis and critical control point (HACCP) and good aquaculture practice. However, infectious diseases in aquaculture are of major concern to the industry and are typically controlled by eradication of the pathogen, treatment with antibiotic or chemotherapeutics, and/or by preventative measures such as the use of probiotics or vaccines. To limit the use of chemicals and antibiotics, good farm management is highly recommended. In terms of treatment, chemicals and antibiotics should be evaluated to establish recommended doses and withdrawal periods, otherwise alternative treatments should be developed. Environmentally-friendly probiotics have been introduced to aquaculture practice in the last decade to replace pathogenic bacteria with beneficial bacteria transient in the gut. Micro-organisms have also been prepared for the purpose of biocontrol and bioremediation. The application of probiotic, biocontrol and bioremediation seem promising; however considerable efforts of further research in terms of food and environmental safety are needed. Vaccination has proved highly effective in controlling diseases in the salmon industry mainly in Europe, America and Japan. In other Asian countries, this practice seem to be slower to develop due to differences in the aquaculture systems used and the economic value of the fish species farmed. Because shrimp farming is a large industry in this region, much effort has been put into developing a vaccine for viral diseases of shrimp. The efficacy of those vaccines remains inconclusive. Immunostimulants are another option developed for use in the shrimp industry in the region; however their efficacy also remains unclear.

Animals↗

PubMed2003

Molecular characterization of the fish-pathogenic fungus Aphanomyces invadans.

Aphanomyces invadans (Saprolegniaceae) is a peronosporomycete fungus associated with the serious fish disease, epizootic ulcerative syndrome (EUS), also known as mycotic granulomatosis. In this study, interspecific relationships were examined between A. invadans isolates and other aquatic animal pathogenic Saprolegniaceae, and saprophytic Saprolegniaceae from EUS-affected areas. Restriction fragment length polymorphisms and sequences of ribosomal DNA confirmed that A. invadans is distinct from all other species studied. A sequence from the internal transcribed spacer region ITS1, unique to A. invadans, was used to design primers for a PCR-based diagnostic test. Intraspecific relationships were also examined by random amplification of polymorphic DNA using 20 isolates of A. invadans from six countries. The isolates showed a high degree of genetic homogeneity using 14 random ten-mer primers. This provides evidence that the fungus has spread across Asia in one relatively rapid episode, which is consistent with reports of outbreaks of EUS. Physiological distinctions between A. invadans and other Aphanomyces species based on a data set of 16 growth parameters showed remarkable taxonomic congruence with the molecular phylogeny.

Animals↗

PubMed2001

Effect of macrophages and serum of fish susceptible or resistant to epizootic ulcerative syndrome (EUS) on the EUS pathogen, Aphanomyces invadans.

Epizootic ulcerative syndrome (EUS) is one of the most destructive diseases of fresh and brackish water farmed and wild fish in the Asia-Pacific region. The in vitro germination and growth of the propagules of the EUS pathogen, Aphanomyces invadans (= A. piscicida), were assessed in the presence of the head-kidney macrophages, serum, and serum heated to inactivate complement proteins, of three EUS-susceptible and one resistant fish species. The susceptible species were: striped snakehead (Channa striata), giant gourami (Osphronemus gouramy) and silver barb [Barbodes (= Puntius) gonionotus], and the resistant species was Nile tilapia (Oreochromis niloticus). Fish of all species were acclimatised to either low temperature (20 degrees C +/- 1.6) at which EUS is known to occur, or to high temperature (32 degrees C +/- 5.0) at which EUS does not occur, except for giant gouramis which were only studied at low temperature. The respiratory burst of the macrophages was assessed in the presence of A. invadans or the stimulant phorbol myristate acetate (PMA), and compared to that of controls. Anti-A. invadans antibody concentrations were assessed in all species except silver barbs. All assays were carried out at the same temperature, regardless of the temperature that the fish were kept at. Macrophages of all species other than snakeheads inhibited fungal germination at both temperatures, though only silver barb and gourami macrophages could inhibit germling growth. PMA increased the respiratory burst in nearly all cases. The respiratory burst in the presence of A. invadans was consistently lower than that of controls, though the difference was only significant in the case of snakeheads. The respiratory burst of all macrophage treatments was higher at a low temperature. Except in the case of PMA-stimulated macrophages, regressions between respiratory burst and inhibitory action were only found in susceptible species, suggesting that the respiratory burst is important in those species, but is unable to prevent the proliferation of A. invadans. Serum inhibited fungal germination in all cases other than low temperature tilapia, indicating that the EUS resistance of tilapia is not due to the serum. Inhibition of germling growth by serum only occurred in silver barbs and gourami. Heated serum did not inhibit germination in any case except that of high temperature snakehead, and in fact stimulated germination in the case of tilapia. Heating serum did not affect the growth inhibiting activity of silver barbs and gouramis, but it stimulated growth in some groups. At high temperatures snakeheads had high anti-A. invadans antibody concentrations, which may explain the inhibitory activity of their heated serum. A role for complement and antibodies in defence against A. invadans in susceptible species is suggested.

Animals↗

PubMed1995

Effects of the organophosphate insecticide, monocrotophos, on acetylcholinesterase activity in the nile tilapia fish (Oreochromis niloticus) brain.

The neurotoxic effects of monocrotophos on the brain of the nile tilapia fish (Oreochromis niloticus) were examined, using a static bioassay under laboratory conditions. By probit analysis the 96 h LC50 value of monocrotophos was 4.9 mg/l. After 96 h exposure to acute levels of monocrotophos, the brain acetylcholinesterase (AChE) activity decreased progressively as the concentration of monocrotophos increased. In addition, four weeks following transfer to toxicant-free water after exposure to 1 mg monocrotophos, nile tilapia fish brain regained 95% of control AChE activity. The results indicate that inhibition of AChE activity in fish exposed to monocrotophos may serve as an indicator of hazard due to application of this chemical in the natural environment.

Acetylcholinesterase↗