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Biomedical subjects

J Poot

Publications and source records attributed to J Poot.

11 recordsLinked to original sources
PubMed2006

Vaccination with a preparation based on recombinant cysteine peptidases and canine IL-12 does not protect dogs from infection with Leishmania infantum.

Cysteine peptidases (CPs) have been implicated in various processes central to the pathogenicity of Leishmania parasites, and are thought to be key factors in the host-parasite interaction. In order to fully evaluate the potential of the CPs as vaccine candidates, studies in natural host species are required. In the study we report here, recombinant L. infantum CPs CPA and CPB were used to vaccinate dogs. In order to induce an appropriate response against the antigens, recombinant canine IL-12 was added as an adjuvant either by itself or in combination with Quil A. After vaccination, dogs were given an intravenous challenge with promastigotes of L. infantum JPC strain. In both vaccinated groups (CPs with IL-12 or CPs with IL-12 and Quil A) CP-specific antibodies were detected after vaccination, indicating that there was a reaction to the vaccine. However, all dogs were found parasite-positive and all developed some degree of clinical leishmaniosis. The observed lack of efficacy of the candidate vaccines could be due, completely or in part, to a number of factors associated with the vaccine antigen, the adjuvant or host-parasite interactions. When compared to results from other studies, it seems less likely that the molecular conformation of the rCPs or rIL-12 caused this lack of efficacy. More plausible explanations are the dose and timing of the IL-12 application and the potentially different effects IL-12 induces as an adjuvant in either the murine or the canine leishmaniosis model.

Adjuvants, Immunologic↗
PubMed1999

Population forecasting with endogenous migration: an application to trans-Tasman migration.

"This article focuses on forecasting migration between Australia and New Zealand (trans-Tasman migration), which is largely visa-free and therefore resembles internal migration. Net trans-Tasman migration is a major component of New Zealand population change and is embedded in this article in a Bayesian or unrestricted vector autoregression (VAR) model, which includes foreign and domestic economic variables. When time series of net migration are available, this approach provides a useful input into forecasting population growth in the short run in the absence of major policy changes. This conclusion applies equally to interregional migration and to unrestricted international migration between economically integrated nations."

Australia↗
PubMed1997

Variation in infection levels with gastrointestinal nematodes in first-year grazing calves in The Netherlands.

ELISAs with crude adult Ostertagia and crude adult Cooperia antigens were used in a survey to monitor the levels of gastrointestinal nematode infections of 21 dairy calf herds. This survey was performed at the end of the grazing season of 1994 in The Netherlands. The mean extinction value of antibody levels of each herd was compared with those of four groups of reference sera of animals that had experienced moderate infection levels (one group), low infection levels (two groups) or no infection (permanently housed group). This was based on faecal examination, pasture larval counts, serum pepsinogen values and worm counts in tracer and main trial calves. The results of the ELISAs indicated a wide variation in infection levels. Most herds (90%) had infection levels equal to, or even lower than, those of the low infection-reference groups. Herds that had been moved every 2 or 3 weeks had lower infections than set stocked herds. The length of the grazing season showed a positive correlation with Ostertagia, but not Cooperia, antibody titres. There was no evident correlation between infection levels and anthelmintic treatment. The implications of these observations in relation to management and nematode control are discussed.

Animal Feed↗
PubMed1997

Controlled dose confirmation study of a 2% moxidectin equine gel against equine internal parasites in The Netherlands.

The efficacy of a 2% moxidectin equine gel at a dosage rate of 0.4 mg kg-1 was evaluated in a controlled trial at Utrecht University. Twelve yearling castrated male Shetland ponies grazed a pasture of 2 ha from May 1994 until housing in November. Six ponies were treated with moxidectin, whereas the others served as non-treated controls. Necropsy was carried out 35 days after treatment. Greater than 99% efficacy of moxidectin was observed on faecal egg output. No effect of moxidectin was observed on mucosal inhibited early cyathostome L3 (EL3) or on the total numbers of mucosal developing stages. However, a 89.6% reduction was observed on large mucosal fourth stage larvae (L4). Moxidectin treatment probably triggered resumption of development of EL3. Moxidectin appeared to be highly effective (95-100%) on lumenal L4 cyathostomes, adult strongylids, Strongylus vulgaris larvae from the arteries, S. edentatus larvae from the abdominal wall and Trichostrongylus axei. Moxidectin had relatively poor efficacy against Gasterophilus intestinalis and had no effect on Anoplocephala perfoliata. No side-effects of moxidectin treatment were observed.

Animals↗
PubMed1997

Use of cloned excretory/secretory low-molecular-weight proteins of Cooperia oncophora in a serological assay.

The potential of Cooperia oncophora excretory/secretory (ES) proteins as antigens in a serological assay which aims to establish exposure levels in cattle was assessed. ES proteins were analyzed by one- and two-dimensional polyacrylamide gel electrophoresis and immunoblotting. The N-terminal domains of two ES proteins were sequenced, and the corresponding cDNAs were cloned. Two cDNAs, designated CoES14.0 and CoES14.2, were expressed in Escherichia coli. The recombinant proteins were tested in an indirect enzyme-linked immunosorbent assay (ELISA) in which crude worm antigen (CWA) was used as a reference standard. In total, 67 reference serum samples were used: 27 negative serum samples, 29 C. oncophora-specific serum samples, 7 Dictyocaulus viviparus-specific serum samples, and 4 Ostertagia ostertagi-specific serum samples. This showed respective sensitivities and specificities of 17 and 84%, 0 and 100%, and 100 and 100% by the ELISAs with the three different types of proteins (CWA, CoES14.0, and CoES14.2, respectively). Since the CoES14.2 ELISA had the best sensitivity and specificity with reference sera, its specificity was further validated in an antigen inhibition ELISA. In this assay CoES14.2 and CWA preparations of C. oncophora, Cooperia curticei, O. ostertagi, Nematodirus helvetianus, Fasciola hepatica, D. viviparus, Haemonchus placei, and Trichostrongylus colubriformus were used as competitor antigens. This experiment showed that only the homologous antigens C. oncophora CWA and CoEs14.2 resulted in 100% inhibition. The CWA preparations of all other nematodes did not affect the ELISA, even if concentrations of 250 times the 50% inhibitory concentration of C. oncophora CWA were used. These results indicate that CoES14.2 does not share cross-reactive epitopes with heterologous CWAs. Finally, we tested the CoES14.2 ELISA with sequential serum samples from naturally infected groups of animals. The optical density values that were obtained correlated well with exposure levels based on cumulative egg excretion. Thus, the CoES14.2 ELISA seems to be a very sensitive tool for estimating exposure levels in cattle.

Amino Acid Sequence↗
PubMed1996

Comparison between fenbendazole and moxidectin applied in a dose and move system for the control of Dictyocaulus viviparus infections in calves.

A grazing study was performed with the main objective to compare the effect of moxidectin (MDT) and fenbendazole (FBZ) in a 'dose and move' system on nematode infections in calves with special emphasis on Dictyocaulus viviparus. Three groups of six calves were grazed from May to October 1994. All groups grazed together until 9 weeks after turnout when they were moved to separate mowed pastures. One group (MM) was then treated with 0.5 mg kg-1 MDT pour-on, the second group (FM) was treated with 7.5 mg kg-1 FBZ drench and the third group served as untreated pasture control group (PC). Two calves from MM and two from FM were experimentally infected with 20 lungworm larvae at turnout in order to initiate low infections in the herd. Pairs of tracer calves grazing during the first 7, 8 or 9 weeks after turnout acquired mean burdens of 218, 255 and 1156 lungworms, respectively. MDT and FBZ treatment removed adult lungworms from MM and FM. In PC faecal larval counts increased until the end of July, when most animals were suffering from lungworm disease. No lungworm disease occurred in both dose and move groups. In FM larvae reappeared in the faeces of some of the calves from 1 month after treatment and low patent infections remained to be present in FM in some calves until the end of the experiment. No reappearance of larvae after treatment was observed in MM. The mean Optical Density (OD) values of the three groups on pasture closely followed the infection patterns. After housing in October all calves, and also a group of five permanently housed non-infected control calves (HC), were infected experimentally with 5000 D. viviparus larvae to evaluate development of immunity. The worm counts at necropsy showed that groups on pasture had developed immunity. However, the degree of immunity was lower in MM than in FM and PC.

Animal Husbandry↗
PubMed1996

Information, communication and networks in international migration systems.

"This paper focuses on the role of information and communication in international migration by means of a survey which covers economic and broader perspectives, both at the micro and macro levels. The human capital model of migration is reviewed and the likely impact of recent and anticipated developments in telecommunications technology is noted. The job search model is reformulated in the context of international migration but extensive modification is required to describe the potential sampling of job offers and other informational needs of international migrants. It is argued that spatial selectivity is to a large extent influenced by migration networks in which information flows play a critical role. This is further elucidated by offering an analytical framework based on the systems approach to migration."

Communication↗
PubMed1993

The role of trans-Tasman migration in forecasting the New Zealand population.

"This article argues that, for the short to medium term, [New Zealand population] projections can be improved upon by adopting econometric methodologies which take explicitly into account the demographic-economic two-way interaction in certain components of international migration. Specifically, the article summarizes research on the causes and consequences of trans-Tasman migration, which is the dominant component of the volatility in New Zealand's net migration. It is shown how these findings can aid population forecasting."

Demography↗
PubMed1993

Adaptation of migrants in the New Zealand labor market.

"This article addresses economic aspects of New Zealand immigration during the 1980s. General features are overall net emigration coinciding with high levels of immigration from Asia and Pacific Island countries. Earnings by years in New Zealand profiles for immigrants with selected occupations are steeper for Pacific Island-born males than for other immigrant groups. Although there are few data, there is some evidence that profiles differ between cohorts."

Culture↗
PubMed1987

Modelling the determinants of trans-Tasman migration after World War II.

"This paper identifies the economic and demographic factors responsible for migration flows between Australia and New Zealand by means of a probabilistic model of emigration in both directions. The largely uncontrolled flows between the two countries have the same determinants as those commonly found in studies of internal migration. The cost of migration (proxied by the real cost of air travel), labour market conditions and the potential earnings differential play a role, although the results are modified by the incidence of return migration and age composition."

Age Factors↗