Direct anthelmintic and immunostimulatory effects of oral dosing semi-purified phytohaemagglutinin lectin in sheep infected with Teladorsagia circumcincta and Trichostrongylus colubriformis.

Lectins are plant secondary compounds that can have anthelmintic properties in vitro. In particular, the phytohaemagglutinin lectin extracted from Phaseolus vulgaris has been shown to inhibit the feeding of Trichostrongylus colubriformis and Teladorsagia circumcincta L1 larvae. However, little is known about the potential anthelmintic properties of this lectin in vivo and its suitability to control gastrointestinal parasite infections in lambs. In a 2 × 2 study, lambs were either orally dosed, or not, with 2.3mg semi-purified PHA lectin per kg live weight (LW) per day, whilst concurrently infected, or not, with 1000 T. circumcincta and 1000 T. colubriformis L3 infective larvae per day for 42 days. There were no adverse clinical effects observed with this dose of PHA lectin. Although worm burdens were similar, animals dosed with PHA lectin had reduced concentration of nematode eggs in the faeces compared with their non-lectin dosed counterparts (P=0.026), suggesting that there may be a direct effect of PHA lectin on parasite fecundity. Irrespective of infection, PHA lectin had immune-stimulatory properties with increased eosinophillia in both abomasal and small intestine tissue sections taken at slaughter on day 42 (P<0.02 for both) and a tendency for decreased ability of Teladorsagia larvae to penetrate abomasal tissue explants (P=0.06). Compared with infection alone, concurrent PHA lectin dosing and infection further increased the number of eosinophils (P<0.01), PAS-positive (mucin-producing cells) (P=0.03) and tended to increase the number of T helper cells (P=0.06). No interactions were observed for cell populations in small intestine tissue sections. These results suggest PHA lectin could have two possible modes of action against T. circumcincta and T. colubriformis, a direct anthelmintic effect on nematode fecundity and an indirect effect through enhancing local immune responses in the host.

In vitro screening of plant lectins and tropical plant extracts for anthelmintic properties.

Lectins are plant secondary metabolites (PSM) found in many forages and which may confer anthelmintic properties to gastrointestinal parasites through disrupting the development of parasitic larvae throughout its life cycle. In experiment 1, the ability of the plant lectins jacalin (JAC), concanavalin A (Con A), phytohemagglutinin E2L2 (PHA-E2L2), phytohemagglutinin L4 (PHA-L4), phytohemagglutinin E3L (PHA-E3L), kidney bean albumin (KBA), Robinia pseudoacacia agglutinin (RPA), Maackia amurensis lectin (MAA), Maclura pomifera agglutinin (MAA), Dolichos biflorus agglutinin (DBA), wheat germ agglutinin (WGA) and Galanthus nivalis agglutinin (GNA) to disrupt the feeding of the first stage larvae (L(1)) of the sheep gastro-intestinal nematodes (GIN) Teladorsagia circumcincta, Haemonchus contortus and Trichostrongylus colubriformis was investigated using a larval feeding inhibition test (LFIT). Only PHA-E3L, WGA and Con A had a potent effect on disrupting larval feeding of all of the three species of GIN investigated. The lectin concentration required to inhibit feeding in 50% of L(1) (IC50) was 7.3±1.2, 8.3±1.4 and 4.3±1.7 µg/ml for PHA-E3L; 59.1±32.4, 58.7±11.9 and 8.1±7.0 µg/ml for Con A and 78.9±11.2, 69.4±8.1 and 28.0±14.1 µg/ml for WGA for T. circumcincta, H. contortus and T. colubriformis larvae, respectively (P=0.006). The addition of the lectin inhibitors fetuin, glucose/mannose or N-acetylglucosamine for PHA-E3L, Con A and WGA, respectively, caused an increase in the proportion of larvae that had fed at all concentrations for PHA-E3L only. In experiment 2, the effect of extracts from the tropical plants Azadiractha indica, Trichanthera gigantea, Morus alba, Gliricidia sepium and Leucaena leucocephala on the feeding behaviour of H. contortus L(1,) was examined. A. indica, T. gigantea and M. alba failed to inhibit 50% of larvae from feeding at concentrations up to 10mg plant extract per ml. In contrast, both G. sepium and L. leucocephala demonstrated a dose-dependent effect on larval feeding with respective IC50 estimates (mean±s.e.) of 0.015 mg/ml ±0.001 and 3.465 mg/ml ±0.144, effects which were partly reversed by the inclusion of either the tannin inhibitor polyethylene glycol or the lectin inhibitor Fetuin. These studies demonstrate that plant lectins can have an inhibitory effect on the feeding behaviour of first stage larvae of ovine GIN in vitro. Moreover they also provide novel evidence that lectins may contribute to the anthelmintic properties of some tropical forage plant extracts, such as G. sepium and L. leucocephala.

Eastern Caribbean family psychology with conduct-disordered adolescents from the Virgin Islands.

Family psychology is a new and relatively undeveloped discipline in much of the English-speaking Caribbean, particularly in the U.S. Virgin Islands. Family structure and youth behavior in the region have changed dramatically over the past few decades. Given the family-oriented nature of the culture, it is posited that the use of family psychology as an approach to research and intervention may prove to be a rich method to address this cultural metamorphosis. This article examines the potential effectiveness of interventions at the family level when mental health providers are working with youth with conduct disorder in the Virgin Islands. This article is offered as a microcosm of the global changes in family structure and the youth culture that are occurring particularly in the developing world, in part due to the rapid development of telecommunications. Possible roles of the family psychologist in this global transformation are presented.

National survey of clinical and subclinical mastitis in Jamaican dairy herds, 1985-1986.

Between April 1985 and August 1986, 89 Jamaican dairy herds with 10 or more cows were visited, 1,645 lactating cows were examined using the CMT test and 254 composite milk samples collected for bacteriological examination. Widespread management faults were noted, especially of milking machine usage and maintenance and the abuse of antibiotics. Fifty-six per cent of all quarters were found to have CMT scores of one or higher, 0.8% showed clinical mastitis and 3.2% were blind. The most common bacterial pathogen Staphylococcus aureus, was recovered from 31% of sampled cows. The resultant milk loss from clinical and subclinical mastitis was estimated to be 20% of the potential national production.

Serological survey for leptospiral antibodies in goats in St Elizabeth Parish, Jamaica, 1985-1986.

A serological survey of goats in St Elizabeth Parish, Jamaica, comprising the breeding herd at the Agricultural Development Corporation (ADC) facility at Hounslow, five commercial herds and 21 family herds was carried out in 1985-1986. The Leptospira microscopic agglutination test indicated that one or more serovars in the Canicola serogroup were the most prevalent. Repeated samplings of goats at ADC, Hounslow demonstrated an increase in portlandvere and canicola seropositive animals following the onset of warmer weather and of icterohaemorrhagiae seropositive animals following the autumn rains and cooler weather. Apart from a cluster of family goats seropositive to pomona there was no geographical separation of reactors to the other serovars tested in the parish.