Gamma-dendrotoxin blocks large conductance Ca2+-activated K+ channels in neuroblastoma cells.

In N1E 115 neuroblastoma cells, gamma-dendrotoxin (DTX, 200 nM) blocked the outward K(+) current by 31.1 +/- 3.5% (n = 4) with approximately 500 nM Ca(2+) in the pipet solution, but had no effect on the outward K(+) current when internal Ca(2+) was reduced. Using a ramp protocol, iberiotoxin (IbTX, 100 nM) inhibited a component of the whole cell current, but in the presence of 200 nM gamma-DTX, no further inhibition by IbTX was observed. Two types of single channels were seen using outside-out patches when the pipette free Ca(2+) concentration was approximately 500 nM; a 63 pS and a 187 pS channel. The 63 pS channel was TEA-, IbTX- and gamma-DTX-insensitive, while the 187 pS channel was blocked by 1 mM TEA, 100 nM IbTX or 200 nM gamma-DTX. Both channels were activated by external application of ionomycin, when the pipet calcium concentration was reduced. gamma-DTX (200 nM) reduced the probability of openings of the 187 pS channel, with an IC(50) of 8.5 nM. In GH(3) cells gamma-DTX (200 nM) also blocked an IbTX-sensitive component of whole-cell K(+) currents. These results suggest that gamma-DTX blocks a large conductance Ca(2+) activated K(+) current in N1E 115 cells. This is the first indication that any of the dendrotoxins, which have classically been known to block voltage-gated (Kv) channels, can also block Ca(2+) activated K(+) channels.

Virulence properties of motile aeromonads isolated from farmed frogs Rana tigerina and R. rugulosa.

Virulence factors were compared in Aeromonas species isolated from clinically normal and septicaemic farmed frogs from Thailand. Haemolysin activities against frog erythrocytes were significantly different within the collection of aeromonads. Groups of high haemolytic activity (unspeciated Aeromonas, Au), moderate haemolytic activity (A. hydrophila), and low haemolytic activity (A. veronii biovar sobria, A. veronii biovar veronii, A. caviae, A. schubertii) were noted. DNA colony hybridisation studies revealed that Au isolates possessed a haemolysin gene (ASH1) which was not present in any of the other Thai aeromonads or type strains tested. Elastinolytic activity was demonstrated in 90% of the Au isolates, 60% of the A. hydrophila isolates and in none of the other motile aeromonads. The cytotoxic activity of the Aeromonas isolates varied according to the source of cells used in the assays. Cells from rainbow trout were extremely sensitive to Au toxins but less so to toxins produced by other species. In contrast mammalian cells showed very little sensitivity to Au toxins but were more sensitive to toxins produced by A. hydrophila. Selection of suitable assay substrates is therefore important.

The protective immune response of yellowtail Seriola quinqueradiata to the bacterial fish pathogen Lactococcus garvieae.

Yellowtail Seriola quinqueradiata were immunized with 2 different Lactococcus garvieae bacterin, formalin-killed KG- phenotype cells (capsulated phenotype) and formalin-killed KG+ phenotype cells (unencapsulated phenotype). These 2 injected vaccines conferred long-term protection to yellowtail against an artificial infection of an encapsulated Lactococcus garvieae strain with long-lasting agglutinating titres against KG+ phenotype cells. However, no agglutinating titres or low agglutinating titres against KG- phenotype cells were detected in fish given each of these bacterin. These results suggested that a capsule in KG- phenotype cells apparently affects their immunogenicity, but the antigens which conferred protection to fish against lactococcal infection may be located on the surface of KG+ phenotype cells, and are not cell capsules in KG- phenotype cells. The protection offered by a formalin-killed KG+ phenotype cell vaccine would not appear to be strain specific. Encapsulated L. garvieae cells were well phagocytosed, and fimbrie-like appendages were seen in KG- phenotype cells after treatment with yellowtail immune serum.

Amoxycillin in the control of furunculosis in Atlantic salmon parr.

The efficacy of amoxycillin in the control of laboratory induced Aeromonas salmonicida infection in Atlantic salmon parr was investigated. When given in the diet at a dose rate of 80 mg per kg bodyweight it was effective against both a moderate and severe challenge (with mortality rates in untreated groups of 75 per cent and 45 per cent). At 40 mg per kg it was effective against the moderate challenge only. The plasma levels in these regimens were 1.25 micrograms per ml and 0.3 to 0.6 micrograms per ml and the minimum inhibitory concentration of the challenge strain of A salmonicida was 0.6 micrograms per ml. The potential of the Charm radiobioassay system in detecting antibiotic residues in fish tissue was studied. The level of amoxycillin in muscle and bone from fish in mid-treatment at 80 mg per kg was 0.32 micrograms per ml. After a 12 day withdrawal period at 18 degrees C no residue was detected within the 0.005 micrograms per ml limit of this test.

Amoxicillin concentrations in the serum of Atlantic salmon (Salmo salar L) during furunculosis therapy.

The effectiveness of the delivery of amoxicillin to Atlantic salmon, undergoing chemotherapy in natural outbreaks of furunculosis in sea-cages, was investigated by measuring the concentration of the drug in serum samples. Five groups of 50 sera from three outbreaks were collected two hours after oral treatment with doses of 80 or 120 mg/kg bodyweight. Amoxicillin was detected in 82, 82, 92, 100 and 90 per cent of the sera in the five groups (limit of detection 0.16 microgram/ml). Many sera contained less than the minimum inhibitory concentration of amoxicillin for the causative agent Aeromonas salmonicida (0.3 microgram/ml), but a concentration more than double the minimum inhibitory concentration was achieved in 2, 2, 56, 32 and 44 per cent of the samples. There was wide variation in the serum concentrations between individuals in the same population and between populations receiving the same treatment; this variation was associated with population factors, the severity of infection and the accuracy of medicating the feed.

Socioeconomic variations in women's diets: what is the role of perceptions of the local food environment?

OBJECTIVES: To test the contribution of perceived environmental factors (food availability, accessibility and affordability) to mediating socioeconomic variations in women's fruit, vegetable and fast food consumption. METHODS: A community sample of 1580 women from 45 neighbourhoods provided survey data on their socioeconomic position (SEP) (education and income); diet (fruit, vegetable and fast food consumption); and the perceived availability of, access to and cost of healthy food in their local area. RESULTS: Once perceived environmental variables were considered, the associations between SEP and diet were weak and non-significant, suggesting that socioeconomic differences in diet were almost wholly explained by perceptions of food availability, accessibility and affordability. CONCLUSIONS: Strategies to decrease socioeconomic inequalities in diet could involve promoting inexpensive ways to increase fruit and vegetable consumption, and ensuring that people of low SEP are aware that many healthy foods are available at relatively low cost. Future research should also confirm if perceptions match objective measures of food availability, accessibility and affordability, in order to address the real and/or perceived lack of healthy options in low SEP neighbourhoods.

Why do women of low socioeconomic status have poorer dietary behaviours than women of higher socioeconomic status? A qualitative exploration.

In developed countries, persons of low socioeconomic status (SES) are generally less likely to consume diets consistent with dietary guidelines. Little is known about the mechanisms that underlie SES differences in eating behaviours. Since women are often responsible for dietary choices within households, this qualitative study investigated factors that may contribute to socioeconomic inequalities in dietary behaviour among women. Semi-structured interviews were conducted with 19 high-, 19 mid- and 18 low- SES women, recruited from Melbourne, Australia, using an area-level indicator of SES. An ecological framework, in which individual, social and environmental level influences on diet were considered, was used to guide the development of interview questions and interpretation of the data. Thematic analysis was undertaken to identify the main themes emerging from the data. Several key influences varied by SES. These included food-related values such as health consciousness, and a lack of time due to family commitments (more salient among higher SES women), as well as perceived high cost of healthy eating and lack of time due to work commitments (more important for low SES women). Reported availability of and access to good quality healthy foods did not differ strikingly across SES groups. Public health strategies aimed at reducing SES inequalities in diet might focus on promoting healthy diets that are low cost, as well as promoting time-efficient food preparation strategies for all women.

The interaction of trimethoprim and quinolones against gram-negative fish pathogens.

The effect of combination of trimethoprim with other non-sulphonamide antibacterial agents, in particular oxolinic acid and nalidixic acid, was evaluated against Gram-negative fish pathogens. The species included Aeromonas salmonicida, Yersinia ruckeri, some Vibrio spp. and Escherichia coli as a reference. The extent of synergy found by other workers with these substances against human Gram-negative bacteria was not apparent here. Some positive interaction between trimethoprim and oxolinic acid was found with Aer. salmonicida, Y. ruckeri and E. coli and between trimethoprim and nalidixic acid with Y. ruckeri in double disc diffusion tests but was not supported by fractional inhibitory concentration indices. The combinations were not effective in preventing emergence of resistance in passage on a drug gradient. Trimethoprim-resistant isolates of Aer. salmonicida were inhibited by low levels of oxolinic acid but the converse did not apply.

Dietary patterns of third-year secondary schoolgirls in Glasgow.

The dietary pattern of 270 third-year secondary schoolgirls in Glasgow was investigated by means of a 24-hour recall. Subjects were asked to indicate any food which they had bought themselves and to answer questions relating to fat, sugar and fibre. Most ate at normal mealtimes including breakfast but additional snacking was prevalent especially in the evening. There was a distinct lack of fruit and vegetables in the diet. The subjects could exercise reasonable influence over their own intake by virtue of their purchasing power. The roles of fat, sugar and fibre in the diet were variably understood and sources of fibre not well recognised.

A review on the use of microorganisms as probiotics.

A literature review on the use of live microorganisms as probiotics is presented. Topics discussed are the definition of probiotic; the normal microflora of the digestive system of mammals, including bacterial interactions in the gut, colonization, modification of metabolic processes, and immunostimulation. Probiotics studies in humans and in farmed animals, with special emphasis on the use of Lactobacillus spp. and Bifidobacterium spp. are also discussed.

RAPD analysis of Aeromonas salmonicida and Aeromonas hydrophila.

The randomly amplified polymorphic DNA (RAPD) technique was used to analyse the genetic differentiation of 13 strains of Aeromonas salmonicida subsp. salmonicida, and seven strains of Aer. hydrophila. Reproducible profiles of genomic DNA fingerprints were generated by polymerase chain reaction (PCR) using a single randomly designed primer. The RAPD profiles of all the non-motile aeromonads, Aer. salmonicida subsp. salmonicida were identical. However, profiles of the motile aeromonads, Aer. hydrophila differed between isolates. These findings reveal genomic homogeneity in Aer. salmonicida subsp. salmonicida and genetic variety in Aer. hydrophila strains.