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Biomedical subjects

S Gallacher

Publications and source records attributed to S Gallacher.

13 recordsLinked to original sources
PubMed2001

The prevalence of familial hypocalciuric hypercalcemia.

Familial hypocalciuric hypercalcemia is said to be an extremely rare condition but is clinically important because it can be confused with primary hyperparathyroidism. The biochemical features of the two conditions are similar, but the former is benign while the latter can have serious clinical consequences with patients occasionally proceeding to parathyroidectomy. It is therefore important to differentiate accurately between the two. With this in mind it would be useful to know the prevalence of familial hypocalciuric hypercalcemia when considering the differential diagnosis of primary hyperparathyroidism. However, as far as we are aware, no estimate of the prevalence of this condition can be found in the literature. We describe how an estimate was made of the prevalence of familial hypocalciuric hypercalcemia in the west of Scotland. We estimate the prevalence to be 1 in 78,000 at least.

Calcium↗
PubMed2001

Comparison of paralytic shellfish toxin (PST) production by the dinoflagellates Alexandrium lusitanicum NEPCC 253 and Alexandrium tamarense NEPCC 407 in the presence and absence of bacteria.

The ability of two Alexandrium species to produce paralytic shellfish toxins (PST) in laboratory culture following the generation of bacteria-free cultures was investigated. The dinoflagellates Alexandrium lusitanicum NEPCC 253 and Alexandrium tamarense NEPCC 407 were cultured in the presence of antibiotics and tested for residual bacteria. After treatment with a cocktail of streptomycin, ciprofloxacin, gentamicin and penicillin G, bacteria could not be detected in either of the treated Alexandrium cultures using 17 different solid and broth bacterial growth media, by epifluorescence microscopy with the dye Sybr green 1, or polymerase chain reaction amplification using universal eubacterial primers designed to target the 16S rRNA gene. Subsequent analysis of A. lusitanicum for PST using high performance liquid chromatography demonstrated that the growth rate and toxin profile remained similar in both bacteria-free and control cultures, although the quantity of toxins produced differed with the bacteria-free culture producing generally more of each compound and also having a greater toxin content in terms of saxitoxin equivalents. A. tamarense also retained similarities between the bacteria-free and control cultures in terms of growth rates and toxin profile, although in this instance, depending on the growth stage and the toxin, the control culture produced more of some toxins than the bacteria-free culture. The control culture was also more toxic in terms of saxitoxin equivalents than the axenic culture. These results suggest that bacteria can influence toxin production in laboratory cultures of Alexandrium species although the mechanisms remain unknown.

Journal Article↗
PubMed2001

Biotransformations of paralytic shellfish toxins by bacteria isolated from bivalve molluscs.

Due to the possibility that bacteria could be involved in the clearance of paralytic shellfish toxins (PST) from bivalve molluscs, investigations into which, if any, bacteria were able to grow at the expense of PST focused on several common shellfish species. These species were blue mussels, oysters, razor fish, cockles, and queen and king scallops. Bacteria associated with these shellfish were isolated on marine agar 2216 and characterized by their carbon utilization profiles (BIOLOG). Selected isolates from groups demonstrating 90% similarity were screened for their ability to metabolize a range of PST (gonyautoxins 1 and 4 [GTX 1/4], GTX 2/3, GTX 5, saxitoxin, and neosaxitoxin) using a novel screening method and confirming its results by high-performance liquid chromatography. Results suggest that molluscan bacteria have different capacities to utilize and transform PST analogues. For example, isolates M12 and R65 were able to reductively transform GTX 1/4 with concomitant production of GTX 2/3, while isolate Q5 apparently degraded GTX 1/4 without the appearance of other GTXs. Other observed possible mechanisms of PST transformations include decarbamoylation by isolate M12 and sulfation of GTXs by isolates Q5, R65, M12, and C3. These findings raise questions as to the possible role of bacteria resident in the shellfish food transport system. Some researchers have suggested that the microflora play a role in supplying nutritional requirements of the host. This study demonstrates that bacteria may also be involved in PST transformation and elimination in molluscan species.

Animals↗
PubMed2000

Marine toxins.

Seafood products are important both nutritionally and economically. Within Europe, some 12 billion Pounds of fishery products are consumed annually and an enormous variety of species are available. Although seafood is rarely implicated in food poisoning, compared to other food sources, it does provide some specific human health hazards unique to this particular resource. Generally, these are toxins from toxic microscopic algae which accumulate through the food-chain. The toxins can cause various neurological and gastrointestinal illnesses and, potentially, consumers are exposed from seafood produced within Europe, from imported products, or from seafood eaten while travelling abroad. The symptoms of illness which may be encountered, the source and mode of action of the toxins, and some emerging problems are described. European legislation aims to ensure the quality and safety of seafood products by prohibiting sale of some toxic species, setting toxin limits, requiring monitoring and controlling imports.

Animals↗
PubMed1998

An interlaboratory study to find an alternative to the MPN technique for enumerating Escherichia coli in shellfish.

Nine laboratories in eight countries tested 16 batches of common mussels (Mytilus edulis) over a 32 week period in order to find an alternative to the Most Probable Number (MPN) technique to enumerate E. coli. The alternatives investigated included the 3M Petrifilm system, the Merck Chromocult agar method and a Malthus conductance technique. The Petrifilm was found to be unsuitable and was subsequently dropped from the trial. After 669 analyses, a correlation of 0.83 was observed for log E. coli counts between the MPN and Chromocult methods and there was no significant evidence that either method tended to give higher readings than the other. The MPN was slightly better than the Chromocult method for repeatability but the Chromocult was slightly better for reproducibility. However, the observed differences are probably too small to be of practical importance. On the basis of these data therefore, the two methods appear equally suitable for E. coli enumeration in shellfish. There were poor correlations between these methods and the Malthus technique. A small but significant number of samples tested positive on the Malthus instrument but were recorded negative on the MPN and Chromocult tests. Subsequent analysis positively identified E. coli from these Malthus assays. After statistical analysis, errors were noted in both the MPN and Chromocult methods but it was found that there would be no statistical differences if the Chromocult agar were used as an alternative to the MPN technique.

Colony Count, Microbial↗
PubMed1998

Development of a bioassay employing the desert locust (Schistocerca gregaria) for the detection of saxitoxin and related compounds in cyanobacteria and shellfish.

Monitoring paralytic shellfish toxins (PST) in shellfish and freshwater cyanobacteria is largely dependent on the mouse bioassay. An alternative assay was devised using the desert locust Schistocerca gregaria. The bioassay successfully identified the optimum extraction procedure for PST from cyanobacterial cells and was also suitable for screening acid extracts of shellfish flesh. These results demonstrate the potential of the locust bioassay for the routine screening of PST in a range of sample matrices.

Animals↗
PubMed1998

Modification of the standard method used in the United Kingdom for counting Escherichia coli in live bivalve molluscs.

The standard method for counting Escherichia coli in live bivalve molluscs is labour intensive and takes three days to obtain a result. Modifications to the standard method were investigated in a collaborative trial conducted in five centres. No significant difference was found between results based on the presence of acid at 24 hours (h) in first stage tests and those based on the presence of acid and gas after 48 h (standard method). The use of the chromogenic medium BCIG (5-bromo-4-chloro-3-indolyl-beta-D glucuronide) agar incubated at 44 degrees C to confirm first stage tests was also found to give equivalent results to conventional confirmation tests. The preferred, modified method removes the presence of gas as a criterion of detection, uses a chromogenic agar medium to confirm the presence of E. coli, and gives results within 48 h. A distribution of simulated samples and selected strains of E. coli to other laboratories using the PHLS external quality assurance scheme for shellfish found no significant difference between results obtained by the standard and modified methods.

Animals↗
PubMed1997

Evidence for production of paralytic shellfish toxins by bacteria associated with Alexandrium spp. (Dinophyta) in culture.

A substantial proportion of bacteria from five Alexandrium cultures originally isolated from various countries produced sodium channel blocking (SCB) toxins, as ascertained by mouse neuroblastoma assay. The quantities of SCB toxins produced by bacteria and dinoflagellates were noted, and the limitations in comparing the toxicities of these two organisms are discussed. The chemical nature of the SCB toxins in selected bacterial isolates was determined as paralytic shellfish toxins by pre- and postcolumn high-performance liquid chromatography, capillary electrophoresis-mass spectrometry, and enzyme immunoassay.

Animals↗
PubMed1992

A tissue culture assay for direct detection of sodium channel blocking toxins in bacterial culture supernates.

A quantitative assay for sodium channel blocking toxins such as tetrodotoxin and saxitoxin has been developed for use with a microtitre plate reader. Mouse neuroblastoma cells, which die rapidly in the presence of ouabain and veratridine, were protected by tetrodotoxin; surviving cells were detected by their uptake of the vital dye Neutral red which was quantified with a microtitre plate reader at 540 nm. A sigmoidal dose response curve was obtained and tetrodotoxin concentrations were readily measured over the range 10 nM to 500 nM (3.2-160 ng/ml). With this method, sodium channel blocking toxins were detected directly, without processing or concentration, in culture supernates of several marine bacteria, including Shewanella alga, Alteromonas tetraodonis, Listonella (Vibrio) pelagia, V. alginolyticus, V. anguillarum and V. tubiashi. Culture supernates of Shewanella alga contained up to 510 ng/ml of sodium channel blocking toxin (using tetrodotoxin as a standard).

Animals↗
PubMedDate not supplied

Paralytic shellfish poisoning toxins induce xenobiotic metabolising enzymes in Atlantic salmon (Salmo salar).

Paralytic shellfish poisoning (PSP) toxins have been implicated as the causative agent of a number of fish kills. Exposure experiments indicate that fish are susceptible to PSPs by intraperitoneal (i.p.) and oral administration, while sampling of fish affected by toxic blooms reveals that these toxins can be accumulated. In spite of the potential impact to marine fisheries, little research has been conducted on the potential metabolism and detoxification of PSPs in marine fishes. Previous work by this group has shown that the xenobiotic metabolising enzyme (XME) cytochrome P-450 (CYP1A) is induced in Atlantic salmon (Salmo salar) following i.p. exposure to saxitoxin (STX). Salmon injected i.p. with sub-lethal doses of STX show a four- to eight-fold induction of hepatic CYP1A (as shown by ethoxyresorufin-O-deethylase activity) over controls after 96 h. Results presented here show that the phase II XME glutathione S-transferase (GST) is also induced in salmon following PSP exposure. Post smolts were exposed to three injections of PSPs (2 micrograms STXeq/kg) over 21 days. Injection of both STX and PSPs extracted from a toxic strain of dinoflagellate (Alexandrium fundyense, CCMP 1719) resulted in induction of hepatic GST, as measured by activity for 1-chloro 2,4-dinitrobenzene. Such inductions indicate a potential role for XMEs in PSP metabolism. Possible roles for other enzymes are also discussed.

Animals↗