Nematode antigens in protection, diagnosis and pathology

A thorough study of parasite antigens is a prerequisite for control programmes based on protection by vaccination, accurate serodiagnosis and perhaps immune modulation to diminish pathological sequelae. Stage specific surface secreted and somatic antigens may be of particular value in proceeding towards these goals. The design of vaccines is most appropriately focused on surface antigens. With respect to pathology, certain antigens must stimulate humoral and, or cellular immune responses which are responsible for the undesirable immunopathologic consequences of the disease. The ultimate objective, therefore, is identification of those particular antigens followed by appropriate down regulation of the immune system in order to delete such potentially harmful immunological reactions. The relevant illustration presented in this context is an interesting correlation between one particular clinical condition of onchocerciasis ("sowda") and the serological response, defined both in terms of the parasite antigen and an immunoglobulin class restricted antibody response. Current parasitological methods of diagnosis consistently underestimate parasite prevalence. Failure to detect low level patent infections incurs the risk of having a reservoir capable of perpetuating infections. There is, then, an urgent requirement for accurate serodiagnosis, to be used in association with, and for the evaluation of, drug treatment and vector elimination in parasite control programmes. Given the high sensitivity of current immunoassay technology, the only bar to establishing the necessary immunological tests is the choice of suitably specific antibody-antigen systems. Once these are identified, a combination of recombinant nucleic acid biochemistry and hybridoma technology should provide the necessary reagents for inexpensive, robust and specific diagnostic tests. In addition, it may not be many years before the ubiquitous RIA and ELISA technology gives way to the newly developing biosensor systems. Finally, given the sensitivity and specificity of today's nucleic acid hybridization techniques, we may soon expect to see specific identification of infective larvae in their vectors of this, a cloned DNA probe specific for Onchocerca volvulus, and with potential for the detection of infective larvae in blackflies is described.     

Involvement of glucagon-like peptide 1 in the glucose homeostasis regulation in obese and pituitary-dependent hyperadrenocorticism affected dogs

The incretin glucagon-like peptide 1 (GLP-1) enhances insulin secretion. The aim of this study was to assess GLP-1, glucose and insulin concentrations, Homeostatic Model Assessment (HOMA_{insulin sensitivity} and HOMA_{β-cell function}) in dogs with pituitary-dependent hyperadrenocorticism (PDH), and compare these values with those in normal and obese dogs. The Oral Glucose Tolerance Test was performed and the glucose, GLP-1 and insulin concentrations were evaluated at baseline, and after 15, 30, 60 and 120 minutes. Both basal concentration and those corresponding to the subsequent times, for glucose, GLP-1 and insulin, were statistically elevated in PDH dogs compared to the other groups. Insulin followed a similar behaviour together with variations of GLP-1. HOMA_{insulin sensitivity} was statistically decreased and HOMA_{β-cell function} increased in dogs with PDH. The higher concentrations of GLP-1 in PDH could play an important role in the impairment of pancreatic β-cells thus predisposing to diabetes mellitus.     

Use of Luprostiol and Cloprostenol for Induction of Parturition in Pregnant Goats

Pregnant goats were induced to parturition on day 145 of pregnancy, with three different protocols: group Cl (n = 19) was injected intramuscularly (IM) with 75 μg of the prostaglandin analogue R‐Cloprostenol; group L (n = 20) was treated IM with 7.5 mg of the prostaglandin analogue Luprostiol; group L₅₀ (n = 18) was injected IM with 3.75 mg of Luprostiol (IM); in addition, Group S (Control, n = 15) was injected IM with 1 ml of saline solution. Thereafter, goats were continuously observed to record the following parameters: parturition, dystocia incidence, placental delivery and kid and maternal survival. Moreover, blood sampling was performed around kidding and plasma progesterone concentrations were analyzed. The interval from injection to parturition (mean ± SEM) was not significantly different among the experimental groups: 35.1 ± 1.5 h, 33.3 ± 0.9 h and 34.1 ± 1.8 h (groups Cl, L and L₅₀, respectively). In the control group, time to parturition was 99.4 ± 12.1 h (range: 34–166 h). All the goats expelled the foetal membranes within the first 2 h after the induction. The incidence of dystocia due to foetal posture was not significantly different between induced and control goats (21.1%, 20.0%, 22.0% and 20%, for groups Cl, L, L₅₀ and S, respectively). The percentage of live kids was practically similar between induced goats (93.9%, 94.9% and 92.1%, for groups Cl, L and L₅₀, respectively); in addition, there was a case of maternal mortality in control group (6.7%; 1/15), whereas there was no mortality in induced goats (0%; 0/57). Plasma concentrations of progesterone showed an intense drop (<2 ng/ml) at 24 h after induction. This study confirms the effectiveness of the luprostiol to induce the parturition in goats, within a narrow range (30–40 h) in most of the induced females (80.0%, 7.5 mg; 77.8%, 3.75 mg).     

Diurnal ACTH and plasma cortisol variations in healthy dogs and in those with pituitary-dependent Cushing's syndrome before and after treatment with retinoic acid

Daytime variations in ACTH and plasma cortisol were studied in healthy dogs and in dogs with pituitary-dependent hypercortisolism (PDH), before and after treatment with retinoic acid. In control dogs ACTH showed a higher concentration at 8.00 AM and between 2.00 and 6.00 PM, with the lowest concentration registered at 10.00 AM (p < 0.05 vs. 8.00 AM and 2.00 PM and p < 0.01 vs. 4.00 PM). Cortisol did not show significant differences. In dogs with PDH, ACTH was lower at 8.00 AM (ACTH: p < 0.01 vs. 2.00 and 4.00 PM; and p < 0.05 vs. 6.00 PM). The lowest cortisol concentration was registered at 8.00 AM and 8.00 PM and the highest at 4.00 PM (p < 0.05 vs. 8.00 AM and p < 0.01 vs. 8.00 PM). After treatment, the lowest ACTH concentration was registered at 10.00 AM (p < 0.01 vs. 2.00 and 4.00 PM). To conclude, the adrenal is desensitized in PDH possibly showing negative in diagnostic tests.     

Ethylcellulose formulations for controlled release of the herbicide alachlor in a sandy soil

The development of controlled-release formulations of alachlor to diminish its leaching in sandy soils, avoiding groundwater contamination and maintaining its efficacy, was studied. For this purpose, ethylcellulose (EC) microencapsulated formulations (MEFs) of alachlor were prepared under different conditions and applied to soil columns to study their mobility. The results show that in all cases the release into water of alachlor from MEFs was retarded when compared with commercial formulation. Total leaching losses in soil columns were reduced to 59% from 98%. The mobility of alachlor from EC microspheres into soil columns has been greatly diminished in comparison with its current commercial formulation (CF), above all with increasing EC/herbicide ratios. Distribution of alachlor applied as MEFs at different depths in the soil was higher in the soil surface (66.3-81.3% of herbicide applied at the first 12 cm). In contrast, the residues from CF along the complete soil column were only 20.4%. From the results of bioassays, MEFs showed a higher efficacy than CF at 30 days after the treatment. The use of ME formulations could provide an advantage in minimizing the risk of groundwater contamination by alachlor and reducing the application rates, as a result of maintaining the desired concentration of the herbicide in the top soil layer, obtaining longer periods of weed control.     

Local Effect of the Corpus Luteum on Ovarian Follicular Functional and Morphological Features in the Goat

Ovaries of unilaterally ovulated goats (n=21) were used to study follicular morphological features (proportion and degree of atresia, oestradiol production in vitro and progesterone production of granulosa cells in culture). Follicles were dissected out and classified as small (1–2 mm), medium (2–4 mm) and large (>4 mm). Morphological and physiological features were compared in each size class between ovaries bearing and not bearing corpora lutea (CLO and NCLO, respectively). Within the same size class, there was no difference in proportion or in degree of atresia, between CLO and NCLO. A significant effect of follicular size on oestradiol production in vitro was detected, but no effect of the corpus luteum was found. Finally, progesterone production of granulosa cells in culture was significantly higher in CLO than in NCLO after 24 h (p < 0.05) and also after 90 h (p < 0.01) of culture. This higher progesterone production by CLO granulosa cells in culture could be explained by local influence of the corpus luteum stimulating the steroidogenic activity but not aromatase activity. Further studies are needed to clarify possible factors and pathways for this local effect of the corpus luteum upon follicular physiology.