Enzyme-linked immunosorbent assay for screening aflatoxin B1 in cottonseed products and mixed feed: collaborative study

A joint AOAC/IUPAC (International Union of Pure and Applied Chemistry) interlaboratory study of an enzyme-linked immunosorbent screening assay (ELISA) for aflatoxins was conducted in laboratories in Canada, France, Japan, South Africa, Switzerland, The Netherlands, Tunisia, and the United States. Twenty-eight samples of raw and roasted peanuts, corn, whole cottonseed, cottonseed meal, ammoniated cottonseed meal, and poultry feed containing various quantities of natural aflatoxins and supplemented when appropriate with aflatoxin B1 were distributed to participating laboratories for testing. The assay is based on conjugation of pure aflatoxin B1 to an enzyme and the competition between this conjugate and (free) aflatoxins in the product for aflatoxin-specific antibodies coated onto microtiter well walls. After a wash step to remove all unbound aflatoxins, a substrate, added to each well, is catalyzed from a colorless to a green solution by any bound enzyme-conjugated aflatoxin B1 present. The intensity of the color decreases as the amount of free aflatoxin B1 in the product increases. Overall correlation was good between ELISA and thin-layer chromatographic (TLC) results for cottonseed products and mixed feed. Variable results were reported for corn and peanut product samples. Although some positive samples (greater than 15 ng/g) of cottonseed products and mixed feed were reported to contain less than 15 ng/g by visual determination, a review of data for absorbance measurements showed that the contamination level was close to the greater than or equal to 15 ng/g standard and would not have been reported as negative under routine screening.(ABSTRACT TRUNCATED AT 250 WORDS)     

The correlation between in-situ,real-time aerosol photoemission intensity and particulate polycyclic aromatic hydrocarbon concentration in combustion aerosols

Aerosol photoemission (APE) has been found to be an excellent surrogate measure of particulate PAH concentration in combustion aerosols under a variety of laboratory and field conditions. Samples of oil stove, automobile exhaust, and urban air particulate matter were concurrently analyzed for aerosol photoemission intensity and particulate PAH concentration. In-situ, real-time analysis of the particulate matter was performed by UV-induced electron photoemission. Two photon energies, 4.9 and 6.7 eV, were chosen for irradiation. The latter energy was more sensitive and less selective. Particulate PAH concentrations were determined by collecting the particulate matter on a filter, solvent extracting the filter, and analyses of the extracts by gas chromatography / mass spectroscopy. Linear correlations (0.84≤r²≤1.00) were observed between aerosol photoemission intensities and the sum of particulate PAH concentrations for laboratory and field studies under a wide variety of conditions. The studies performed to date cover a dynamic range of three orders of magnitude (1 to 1000 ng / m³). The time resolution is in the order of a few seconds.     

The effect of photoperiod on growth, survival, colour and activity of juvenile southern rock lobster, Jasus edwardsii

Juvenile (1–10 g) southern rock lobsters, Jasus edwardsii, were subjected to five photoperiods [0L(light):24D(dark); 6L:18D; 12L:12D; 18L:6D; 24L:0D] during a 112‐day trial, and growth, survival, colour, food consumption and activity were examined. Lobsters grown under the 6L:18D and 24L:0D photoperiods had significantly lower (P < 0.05) final mean weight and specific growth rate than any other treatments. Photoperiod had no effect on survival or colour of lobsters. Food consumption differed significantly during the first week of the trial; after 5 weeks, food consumption was similar in all treatments. Major peaks in activity occurred during dark periods for lobsters exposed to photoperiods that had a light:dark regime. Activity of lobsters exposed to continuous light or dark regimes remained constant and at low levels during the 24‐h period. Food consumption or activity does not appear to determine the rate of growth of lobsters in the different photoregimes. One over‐riding outcome of this and other studies on photoperiod is that the growth and survival response of juvenile J. edwardsii was not significantly better than those of the standard 12L:12D cycle.     

Effect of gonadectomy on subsequent development of age-related cognitive impairment in dogs.

OBJECTIVE: To determine whether gonadectomy predisposes dogs to development of age-related behavioral changes linked to cognitive impairment. DESIGN: Cohort study. ANIMALS: 29 sexually intact male dogs, 63 spayed female dogs, and 47 castrated male dogs 11 to 14 years old. PROCEDURE: Information on possible impairments in 4 behavioral categories linked to cognitive impairment (orientation in the home and yard, social interactions, house training, and sleep-wake cycle) was obtained from owners of the dogs by use of a structured telephone interview format. A second interview was performed 12 to 18 months after the initial interview, and differences in responses were evaluated. RESULTS: Sexually intact male dogs were significantly less likely than neutered dogs to progress from mild impairment (i.e., impairment in 1 category) to severe impairment (i.e., impairment in > or = 2 categories) during the time between the first and second interviews. This difference was not attributable to differences in ages of the dogs, duration of follow-up, or the owners' perceptions of the dogs' overall health. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that the presence of circulating testosterone in aging sexually intact male dogs may slow the progression of cognitive impairment, at least among dogs that already have signs of mild impairment. Estrogens would be expected to have a similar protective role in sexually intact female dogs; unfortunately, too few sexually intact female dogs were available for inclusion in the study to test this hypothesis. There may be a need to evaluate possible methods for counteracting the effects of loss of sex hormones in gonadectomized dogs.     

A novel approach to growth promotion using auto-immunisation against somatostatin. I. Effects on growth and hormone levels in lambs

Nine three-week-old lambs were immunised against somatostatin linked to human serum globulin. Significant antibody titres were obtained in all these lambs. The rate of weight gain was greater in those animals immunised against somatostatin (treated) than in the control animals which were immunised against globulin alone (P < 0.001). The final height of the treated lambs was also significantly greater (P < 0.05) as a result of increased height velocity during the period of treatment (P < 0.01).Evaluation of the animals both before and after slaughter indicated that there was no effect of treatment upon body composition, but rather that there had been proportional growth. The carcass assessments revealed that the treated lambs had a longer leg-length (P < 0.01) and had a greater warm carcass weight (P < 0.05) than the control animals, but had similar scores for fat and muscle covering. There was no difference in wool weight between the two groups.No significant difference was found between the groups in the basal levels of either insulin or growth hormone. However, growth hormone release following arginine infusion was greater in the treated animals. There was also a small, but significant, difference (P < 0.05) in the levels of bioassayable somatomedin activity between the treated and control lambs, the treated lambs having higher somatomedin activity.Histological examination of the pancreas from control and treated lambs revealed an increased incidence of abnormalities (mainly acinar necrosis and loss of beta-cell staining) in the islets of Langerhans in the treated lambs, but it could not be concluded that auto-immunisation against somatostatin produced any specific morphological change in the betacells of the pancreatic islets.The results of this study suggest that somatostatin plays an important physiological role in regulating growth stimulation. Removal of the inhibitory effect of somatostatin (in this case by neutralisation of the effect with antibodies) can result in increased growth. The hormonal changes induced by this treatment have yet to be fully elucidated. Further investigations are required to assess the usefulness of this treatment as an alternative to the more conventional synthetic steroid treatments for growth promotion.     

The presence and distribution of beta-galactosidases in the small intestinal mucosa of the neonatal dog.

The beta-galactosidase activity of the small intestinal mucosa of the neonatal dog has been studied over the pH range 3-0 - 5-8 using different substrates and in the presence and absence of p-chloromercuribenzoate. Partial separation of two beta-galactosidases has been achieved by gel filtration. The results suggest that three beta-galactosidases, comparable with those in other mammals, exist in canine small intestinal mucosa.     

Ultrastructural features of Cowdria ruminantium in midgut epithelial cells and salivary glands of nymphal Amblyomma hebraeum

Colonies of Cowdria ruminantium were studied in midgut epithelial cells and salivary gland acini of nymphal Amblyomma hebraeum that were infected experimentally as larvae. Colonies were found in both tissues and studied with light and electron microscopy. Colonies observed within gut cells frequently contained 2 types of the organism: electron-dense and reticulated forms. The morphology of colonies from salivary glands, as seen with light microscopy, varied from compact, densely-staining, small colonies to larger ones in which individual organisms were apparent. With electron microscopy, most organisms in salivary glands were reticulated and appeared to be dividing by binary fission. In both types of host cells, colonies often contained a dense inclusion to which reticulated organisms were adhered.