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Biomedical subjects

J H Boon

Publications and source records attributed to J H Boon.

At least 19 recordsLinked to original sources
PubMed1995

[A study of the cause of massive mortality among marine-cultured rainbow trout (Oncorrhynchus mykiss, Walbaum) in a fish farm in the southwestern Netherlands].

The present study investigated the mass mortality of marine cultured young rainbow trout (Oncorhynchus mykiss, Walbaum) in the Netherlands. The course of the disease, the clinical symptoms, and bacteriological and virological investigations lead to the diagnosis: 'primary infectious pancreatic necrosis virus (IPNV) infection followed by secondary vibriosis'. Treatment with flumequine seemed to be effective. The trout were possible infected with IPNV at the trout hatchery and nursery from which they originated.

Animals↗
PubMed1995

Production, characterisation and applicability of monoclonal antibodies to European eel (Anguilla anguilla L., 1758) immunoglobulin.

Monoclonal antibodies (mAbs) to European eel (Anguilla anguilla L., 1758) immunoglobulin (Ig) were produced, characterised and tested for applicability in a number of immuno(cyto)chemical assays. The selected mAbs, WEI 1 and WEI 2, were specifically reactive with Ig heavy and light chain, respectively. WEI 1 appeared to react with all or nearly all Ig molecules, B cells and plasma cells. WEI 2 was reactive with a subpopulation of those cells, indicating that European eel possesses at least two antigenically different light chain types. Both mAbs could be used for detection of antigen-specific antibodies in plasma by means of an enzyme-linked immunosorbent assay (ELISA).

Anguilla↗
PubMed1995

Influence of flumequine on in vivo mitogen responses of European eel (Anguilla anguilla L., 1758) lymphoid cells.

The influence of flumequine on mitogen induced lymphoid cell proliferation in European eels (Anguilla anguilla L., 1758) was studied. For this purpose an in vivo test, using peroral drug administration followed by successive intraperitoneal injections with concanavalin A (ConA) or bacterial lipopolysaccharides (LPS) and 5-bromo-2'-deoxyuridine, was applied. Direct counting of proliferated cells in blood smears revealed that flumequine possesses mitogenic properties. A synergistic and an antagonistic effect of the drug was observed after LPS and ConA stimulation, respectively. Flow cytometric analysis of peripheral blood lymphoid cells showed a significant reduction of the mean proportion surface immunoglobulin positive cells in the flumequine-treated animals. It is concluded that flumequine enhances proliferation of lymphoid cells (probably surface immunoglobulin negative cells) in eel under the present experimental conditions.

Animals↗
PubMed1992

[Animal and veterinarian out of equilibrium?!].

Veterinarians can influence how animals are kept, and the way animals are kept can influence animal health and well-being. Veterinarians may come into conflict with themselves as this is also partly their responsibility. This conflict might have consequences for the aptitude of the individual to be a veterinarian.

Animal Husbandry↗
PubMed1990

Influence of gastro-intestinal nematodes on the productivity of dairy cattle in the wet highlands of Sri Lanka.

To study the response and economics of nematode control in cattle, trials with anthelmintics were carried out in the wet season at New Zealand farm in the highlands of Sri Lanka. Three age groups were used: stall fed yearlings, grazing heifers and lactating cows. Groups were treated with ivermectin or febantel and monitored along with control groups for faecal egg counts, growth and milk production. Treatment reduced the trichostrongylid faecal egg counts in yearlings, heifers and cows for six to 10 weeks, for more than 10 weeks and for 140 days respectively. The growth rate of treated yearlings did not increase significantly while treated heifers did grow significantly faster. Treated cows produced an average of 115 kg more milk over 133 days (P less than 0.05). The economic gains in reducing the age at first service and in terms of milk yield far outweighed the cost of anthelmintics used.

Animals↗
PubMed1989

The effects of Dictyocaulus viviparus infection on energy metabolism of calves.

To determine the effects of lungworm infection on energy metabolism and rate of weight gain, five 3-mo-old male Friesian calves were infected orally twice each week with 640, third-stage larvae of Dictyocaulus viviparus (D.v.) over an 8-wk period. Infected calves were matched with uninfected controls on the basis of similar rates of feed consumption and weight gain during the acclimation period before infection. Infected calves were fed 2 kg of concentrates daily (88% DM), about 8.5 Mcal/d. Controls each received approximately 250 g less, about 7.5 Mcal/d. Similar amounts of hay (5.6 to 5.8 Mcal/d) were provided to all calves. Clinical, serum chemical, hematological and parasitological criteria, weight gain and utilization of energy were monitored on a weekly basis. Serum chemical and hematological analyses and clinical examinations of infected animals revealed signs typical of lungworm infection. Fecal and sputum sample examinations for infected calves were positive for D.v. larvae and ova, respectively. Control animals gained approximately 80 g.animal-1.d-1 more than infected calves. Lungworm infection had no significant effect on digestibility of energy or protein. Metabolizability of energy ingested was somewhat higher in the infected calves due to a higher dietary concentrate to roughage ratio. Utilization of metabolizable energy and protein tended to be less efficient for infected animals. Results showed that D.v.-infected calves need more feed for gain than do uninfected animals. This extra requirement is due to an increased maintenance requirement and probably to a reduced protein retention from digested protein.

Animals↗
PubMed1988

Clinical signs following experimental lungworm infection and natural bovine respiratory syncytial virus infection in calves.

Similar clinical signs have been reported in calves infected either by Dictyocaulus viviparus or bovine respiratory syncytial virus. Three experiments were carried out to establish the clinical picture and the course of the disease in animals with these infections. The clinical signs of calves infected with lungworm included coughing, nasal discharge, tachypnoea, abdominal breathing and pyrexia, and auscultation of their lungs revealed increased bronchial sounds. Similar signs were also observed after infection with bovine respiratory syncytial virus, but the signs were more acute and resolved more rapidly than in animals infected with lungworm larvae. Calves infected with lungworm had more serious clinical signs after infection with bovine respiratory syncytial virus than calves, which were not infected with lungworm.

Animals↗
PubMed1987

Relationship between cytologic changes in bronchoalveolar lavage fluid and weight gain in calves with gastrointestinal nematodes and lungworms.

Two of three groups of 10 calves each were infected with either 100,000 infective larvae (L3) of Ostertagia spp. and 100,000 L3 of Cooperia spp. or with 4000 L3 of Dictyocaulus viviparus, respectively, at the age of 14 weeks. The third group was not infected. After treatment with an anthelminthic five calves from each group were challenged with either 100,000 L3 of Ostertagia spp. and 100,000 L3 of Cooperia spp. or 4000 L3 of Dictyocaulus at the age of 20 weeks. The calves were 25 weeks old when slaughtered. Total and differential cell counts were determined in bronchoalveolar lavage fluid and showed that neutrophils were the most frequent and eosinophils the least frequent cell present. There was a significant negative relationship between eosinophil levels and weight gain of the calves.

Analysis of Variance↗
PubMed1986

Sero-epidemiological survey of Dictyocaulus viviparus infections in first-season grazing calves in The Netherlands.

A sero-epidemiological survey of Dictyocaulus viviparus infections in calves was carried out using an enzyme-linked immunosorbent assay. Infection level with D viviparus was correlated with farm, herd and management characteristics. At least 75 per cent of the herds were infected with D viviparus. Calves on zero-grazing farms were infected at a lower level than calves grazing pasture. No regional differences in infection rate were observed. On 15 per cent of the farms calves had clinical husk while 51 per cent of farms had experienced husk in the past. A higher level of infection was seen when calves were housed later in the autumn. The number of calves grazing together and the stocking rate had a significant positive influence on the level of infection. No significant difference in the occurrence of clinical husk was observed between calves vaccinated against lung-worm disease and calves not vaccinated against the disease.

Animals↗
PubMed1986

Use of ELISA to assess lungworm infection in calves.

The enzyme-linked immunosorbent assay (ELISA) technique was applied to the detection of lungworm infections in calves. In experimentally infected animals different responses to larval and adult worm antigens were observed. The response to adult worm antigens was delayed in vaccinated animals when infection occurred by the gradual uptake of infective larvae from contaminated pasture. A serological survey in The Netherlands demonstrated a high incidence of lungworm infection in both vaccinated and unvaccinated herds. There was a good correlation between anti-adult worm and anti-larval ELISA-titres. ELISA appeared to be a useful technique for assessing the level of lungworm infection in a herd.

Animals↗
PubMed1986

Effect of infection with lungworms (Dictyocaulus viviparus) on energy and nitrogen metabolism in growing calves.

1. Ten Friesian male calves of about 100 kg and 3 months old were reared similarly and were worm-free. From 13 weeks of age five calves received a dose of 640 infective larvae (L3) of lungworms (Dictyocaulus viviparus) twice weekly for 8 weeks to simulate continuous infection. Animals not infected were fed to the same level as the infected animals (about 1.2-1.3 kg concentrates and 1.4-1.5 kg good-quality hay/d). 2. Heat production was measured twice weekly during 48 h (days 2 and 3, and days 5 and 6) in each group of experimental animals. 3. Infection caused considerable damage to the lungs, increased respiration frequency and clearly produced antibody titres against D. viviparus. 4. Animals infected with lungworms had on average a lower rate of weight gain, reduced by 70 g/d per animal. Digestibility was not affected. Nitrogen retention was much lower in infected animals (12.0 v. 14.6 g/d per animal in controls). 5. Metabolizability of energy was slightly reduced in infected animals. Heat production as found in infected animals may be associated with an increased maintenance energy requirement of 30 kJ/kg live weight 0.75 per d or reduced partial efficiency of feed conversion above maintenance in animals infected with lungworms (58.5 v. 64.1% in the control animals). 6. It was concluded that the depression in rate of gain was related to reduced intake of feed and to decreased N retention.

Animal Feed↗
PubMed1985

Physiological effects of experimental verminous bronchitis in Friesian calves.

Pulmonary function values were measured in five Friesian calves of five months of age during the patent phase of an experimental moderate lungworm infection and were compared with the pulmonary function values recorded in four control animals. All the nine calves were free of any previous challenge with Dictyocaulus viviparus and were submitted to the same standardized conditions of body conformation, housing, feeding and procedures for pulmonary function testing. A significant increase of respiratory rate, minute ventilation, total pulmonary resistance and power of breathing and a significant decrease of tidal volume, dynamic lung compliance and PaO2 were observed in the infested animals. The absolute intrapleural pressure values were also significantly more negative. The conclusions of the statistical analysis were almost identical when predicted instead of measured pulmonary function values were used in the control group. The clinical, functional and pathological findings in the infested animals were all consistent with the picture of a lower airway obstructive disease.

Animals↗
PubMed1984

Parasitological, serological and clinical effects of continuous graded levels of Dictyocaulus viviparus inoculations in calves.

To investigate the parasitological, serological, clinical and growth effects of continuous graded levels of Dictyocaulus viviparus inoculations in calves an experiment was carried out with 10 groups of 5 calves each. Calves were inoculated twice a week during a period of ten weeks. The range of the doses was 10-2560 infective larvae (L3) per inoculation. The results were analysed by linear and curvilinear regression of various traits on infection level. It is concluded that: A continuous exposure of calves to L3 of D. viviparus was followed by a continuous larval excretion at all levels; Results of the ELISA technique gave a very good reflection of the level of infection; Clinical signs and weight loss were evident before the parasitological and serological results were positive; The serological parameter and the parasitological parameters were mainly linearly related to the level of infection. The clinical parameters were mainly cubically related to the level of infection.

Animals↗
PubMed1984

The incidence of Dictyocaulus viviparus infections in cattle in the Netherlands. II. Survey of sera collected in the field.

Examination of nearly 2000 sera indicated that approximately 90 per cent of cattle had acquired Dictyocaulus viviparus infections during the previous grazing season. No differences were found between provinces. Large differences were seen between herds. Antibody titres of milk cows on zerograzing farms were significantly lower than on comparable farms where animals were pastured. The need for further epidemiological work is stressed. In such work serology can be helpful.

Animals↗
PubMed1983

[Lungworm disease in cattle, a persistent problem?].

From the results of a number of studies it is concluded that: (1) Cattle of a large proportion (approximately 80 per cent) of the dairy farms in the Netherlands were infected with L3 larvae of Dictyocaulus viviparus during the grazing season in 1981. (2) Experiments showed a significant negative cubic effect on the level of infection with L3 larvae of D. viviparus on the growth of calves. (3) Sporangia of Pilobolus kleinii harbouring L3 larvae were shot significantly further away than sporangia not harbouring L3 larvae.

Animals↗
PubMed1982

The incidence of Dictyocaulus viviparus infections in cattle in The Netherlands. I. The Enzyme Linked Immunosorbent Assay as a diagnostic tool.

The Enzyme Linked Immunosorbent Assay (ELISA) provides a very efficient technique for detecting antibodies against Dictyocaulus vivparus in calves. Although low level cross reactions were found in animals with gastrointestinal nematodes, the specificity and sensitivity of the technique are sufficient for herd diagnosis of lungworm infections and for survey work. This conclusion is reached on the basis of artificially and naturally infected calves. ELISA titres correlate well with Indirect Haemagglutination titres, parasitological findings, and clinical observations.

Analysis of Variance↗
PubMed1980

[Studies on the possible causes of cough in calves at pasture (author's transl)].

Respiratory disease occupies a prominent position in the series of common diseases in calves. Efforts were made to take an inventory of possible causes of cough in calves at pasture. For this purpose, a number of calves on twenty-three, ten and eight mixed farms respectively were clinically studied during the period from 1975 up to and including 1977. Faecal, sputum and serum samples were collected to examine them for the presence of husk worm larvae, husk worm eggs, antibodies to specific viruses and lung worms. In 1978, titres of antibodies to lung worms were determined in the serum samples of a large number of calves from forty-five farms. From the findings obtained, conclusions were drawn regarding the prevention of virus and lung worm infections in calves at pasture and regarding the diagnosis and prevention of verminous bronchitis in these animals.

Animals↗