Efficacy of commonly used anthelmintics: first report of multiple drug resistance in gastrointestinal nematodes of sheep in Trinidad.

In Trinidad, small ruminant farms are semi-intensively managed under tropical conditions which support the development and survival of the infective stages of the helminths. Local farmers use anthelmintics to control gastrointestinal nematodes frequently. Frequent use of anthelmintics has the potential to select for populations of nematodes resistance to those chemicals. Hence, an attempt was made to study the efficacy of commonly used drugs on gastrointestinal nematodes of sheep. Three farms situated in different counties in Trinidad were selected. Sheep aged 6-15 months and not treated with anthelmintics for a minimum of six months previous and with faecal egg count (FEC)>150 eggs per gram were selected for study. They were allocated into 5 groups, each consisting 10 animals. The Group TA animals were treated once with albendazole (5mg/kg. b.wt.), group TF with fenbendazole (5mg/kg.b.wt.), group TI animals with ivermectin (200 µg/kg b.wt.), group TL with levamisol (7.5mg/kg b.wt.). The group NTC animals were not given any drug and served as control. The number of nematode eggs per gram of faeces from each animal was determined before treatment and at 14 days after treatment. The anthelmintic susceptibility to different drugs was detected by FECRT (in vivo) with EPG recorded at 14 day post-treatment. The data analysis using FECRT revealed that efficacy of albendazole (46-62%), fenbendazole (44-61%) and levamisol (53-81%) were reduced compared to ivermectin (95-97%). An attempt has also been made to find a suitable method for calculation of FECR (%).

Effect of water extract of carica papaya seed on the germinal epithelium of the seminiferous tubules of Sprague Dawley rats.

Extracts from different parts of the papaya have been reported to decrease the testicular weight of Wistar rats when administered orally for 8 weeks. It was however reported that suppression of spermatogenesis was observed in these rats following the administration of papaya seed extract. No histological abnormality was observed in these animals. In this experiment, water extract of papaya seeds, was administered orally to Sprague Dawley rats ad libitum for 8 weeks. Results showed that 3 weeks after commencement of this administration, the lumina of the seminiferous tubules were more prominent and empty in the experimental animals with no evidence of spermatids and spermatozoa. It also showed that the lateral walls of adjacent Sertolil cells lost contact with each other.

Antidiarrhoeal effects of Ocimum gratissimum leaf extract in experimental animals.

The aqueous extract of the leaves of Ocimum gratissimum was screened for antidiarrhoeal effects. The extract inhibited castor oil-induced diarrhoea in rats as judged by a decrease in the number of wet faeces in the extract-treated rats. In addition, the extract inhibited the propulsive movement of intestinal contents. On the isolated ileum of guinea-pig, the extract showed no direct action; however, it reduced the responses of the guinea-pig ileum to acetylcholine, nicotine and histamine. Phytochemical tests revealed the main constituents as tannins, steroids, triterpenoid and carbohydrates. These findings suggested that the aqueous extract of the leaves of O. gratissimum might elicit an antidiarrhoeal effect by inhibiting intestinal motility, partly via muscarinic receptor inhibition.

Effects of triiodothyronine treatment on pharmacokinetic properties and metabolite formation of antipyrine in dwarf goats.

The influence of triiodothyronine (5 micrograms/kg of body weight, sc, q 12 h for 7 days) on antipyrine (AP, 25 mg/kg, IV) plasma elimination and urinary metabolite excretion was studied in castrated male dwarf goats. After triiodothyronine treatment, a significant increase in AP elimination was found. However, the observed changes in clearances for production of AP metabolites (nor-AP, 3-hydroxymethyl-AP; 4-hydroxy-AP, and 4,4'-dihydroxy-AP) do not suggest a clear selectivity of triiodothyronine toward any of the metabolic pathways of AP.

Effects of Ehrlichia phagocytophila infection on serum thyroid hormone concentrations and on antipyrine clearance and metabolite formation in dwarf goats.

The influence of infection with Ehrlichia phagocytophila (EP) on serum thyroid hormone concentrations and on antipyrine (25 mg/kg of body weight, IV) plasma elimination and urinary metabolite excretion was studied in castrated male dwarf goats. Mean thyroid hormone concentrations moderately decreased in EP-infected goats, with maximal decrease in total and free triiodothyronine and thyroxine serum concentrations of 56, 64, 23, and 19%, respectively. The estimated pharmacokinetic values of antipyrine (AP) in EP-infected goats were similar to those in the goats when healthy. However, glucuronidation of the AP-metabolites 3-hydroxymethyl-AP, 4,4'-dihydroxy-AP, and 4-hydroxy-AP was reduced during the febrile episode of the acute-phase response to EP infection.