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Biomedical subjects

C V Nielsen

Publications and source records attributed to C V Nielsen.

17 recordsLinked to original sources
PubMed2003

Comparative susceptibility of two races of Salmo salar (Baltic Lule river and Atlantic Conon river strains) to infection with Gyrodactylus salaris.

The susceptibility of various races of salmonids towards infections with the skin parasitic monogenean Gyrodactylus salaris Malmberg, 1957, differs markedly. Norwegian and Scottish salmon strains are known as extremely susceptible to infection, whereas Baltic salmon races such as the Neva strain (Russian origin) and the Indals river (Swedish origin) salmon have been characterized as relatively resistant. However, the status of the many other Baltic strains has remained unknown. The present study reports on the susceptibility of the Baltic salmon from the Swedish river Lule. It was shown that this strain is susceptible to infection but to a lesser extent than the Scottish salmon. Further studies showed that injection of immuno-suppressants (dexamethasone) greatly increased population growth of G. salaris on Scottish salmon but not on the Baltic salmon. Mucous cell density on fins differed between strains, and a general trend to decreased cell density on infected fish 8 wk post-infection, compared to uninfected fish, was observed. The largest decrease in mucous cell density following infection was seen in the most resistant fish. After administration of immuno-suppressants, this decrease in mucous cell density was inhibited in the Scottish salmon but not in the Baltic salmon. Thus, there seems to be a relationship between the fishes' ability to discard mucous cells and the ability to resist infections with Gyrodactylus salaris. Although the Lule salmon seems more susceptible to infection compared to previous reports on the Neva salmon, the results support the notion that Baltic salmon strains are generally more resistant than East Atlantic salmon.

Animals↗
PubMed2003

Increased susceptibility of Atlantic salmon Salmo salar to infections with Gyrodactylus derjavini induced by dexamethasone bath treatment.

Dexamethasone, a known immunosuppressant, was administered by bath or injection to Atlantic salmon Salmo salar (Conon stock) to study if this treatment could affect the susceptibility of fish to infections with a Danish strain of Gyrodactylus derjavini (Monogenea). Three groups of S. salar (Conon stock) were immersion treated either with 10, 60 or 240 microg dexamethasone l-1 water, respectively. In addition, one group (positive control) was treated intraperitoneally with 200 microg dexamethasone per fish and one negative control group was kept untreated. A single G. derjavini parasite was placed on the anal fin of each fish and the infection was subsequently monitored weekly for 6 weeks. An increase in parasite populations on the salmon was positively correlated with the amount of immunosuppressant used. Infection levels in the group immersion treated with dexamethasone (240 microg l-1 water) and in the i.p. treated positive control group were significantly higher compared to the untreated control group.

Administration, Cutaneous↗
PubMed2001

Host responses against the fish parasitizing ciliate Ichthyophthirius multifiliis.

Recent studies have shown that fish are able to mount protective immune responses against various parasites. One of the best characterized parasite-host system in this context is the ciliate Ichthyophthirius multifiliis (Ich) parasitizing a range of freshwater fishes. Both specific and non-specific host defence mechanisms are responsible for the protection of fish against challenge infections with this ciliate. The specific humoral components comprise at least specific antibodies. The non-specific humoral elements included are the alternative complement pathway and probably lectins. Cellular factors involved in the specific response are B-cells and putative T-cells. The non-specific effector cells recognized are various leukocytes. In addition, goblet-cells and mast cells (EGC-cells) may have a function. The NCC-cell (suggested analogue to NK-cells in mammals) seems to play a role in the non-specific response. This well documented protective response in freshwater fishes against Ich has urged the development of anti-parasitic vaccines. Indeed, such products based on formalin killed parasites have been developed and found to offer the vaccinated host a satisfactory protection. However, the collection of parasites for vaccine production is extremely laborious. It involves keeping infected fish due to the fact that in vitro propagation of the parasite is still insufficiently developed. Gaining knowledge of amino acid sequences and its encoding DNA-sequences for the protective antigens (i-antigens) in the parasite was a major breakthrough. That achievement made it possible to produce a recombinant protein in E. coli and preliminary results indicated a certain protection of fish vaccinated with this product. Recent work has shown that the free-living and easily cultivated ciliate Tetrahymena can be transformed and express the i-antigen. This path seems to be promising for future development of vaccines against Ich. A novel approach in fish is the development of DNA-vaccines. Successful DNA-vaccination trials have been conducted in fish against viral infections and the technology also makes it possible to develop a DNA-vaccine against Ich. Other approaches to immuno-protection against Ich have been the use of heterologous vaccines. Thus, both bath and injection vaccination using live or killed (un-transformed) Tetrahymena has been reported to offer treated fish a certain level of protection. Such protection could be explained by non-specific reactions and the efficacy and duration of this vaccination type should be further evaluated.

Animals↗
PubMed2001

Fraunhofer diffraction of atomic matter waves: electron transfer studies with a laser cooled target.

We have constructed an apparatus combining the experimental techniques of cold target recoil ion momentum spectroscopy and a laser cooled target. We measure angle differential cross sections in Li(+)+Na-->Li+Na(+) electron transfer collisions in the keV energy regime with a momentum resolution of 0.12 a.u. yielding an order of magnitude better angular resolution than previous measurements. We resolve Fraunhofer-type diffraction patterns in the differential cross sections. Good agreement with predictions of the semiclassical impact parameter method is obtained.

Journal Article↗
PubMed2001

Long-term sickness absence - risk indicators among occupationally active residents of a Danish county.

This study aims to identify risk factors and their prevalence in long-term sickness absence. The study is designed as a case-referent study which comprises 481 participants who have experienced a sickness absence lasting >10 weeks and a reference group of 1326 individuals in active employment. Multivariate analysis identified the following significant risk factors for men: (i) age >50 years [odds ratio (OR) = 2.4]; (ii) short period of education (OR = 2.3); (iii) unemployment within the last 3 years (OR = 1.7); (iv) heavy-duty work (OR = 2.1); (v) monotonous, repetitive work (OR = 1.7); (vi) lack of job satisfaction (OR = 2.1); and (vii) much back pain during the last 3 years (OR = 2.1). The following risk factors were identified for women: (i) leaving school without graduation (OR = 2.6); (ii) unemployment within the last 3 years (OR = 1.5); (iii) heavy-duty work (OR = 2.8); (iv) lack of influence on own job situation (OR = 2.1); and (v) much back pain within the last 3 years (OR = 1.8). It is concluded that the identification of working environment risk factors constitutes a case for improvement of the working environment which may be instrumental in reducing long-term sickness absence.

Absenteeism↗
PubMed2001

Effect of early vocational intervention in a rheumatological outpatient clinic--a randomized study.

This study aims to explore the effect of vocational intervention in a rheumatological outpatient clinic. The study is designed as a randomized study with intervention in 108 patients and with 93 patients serving as controls. The study population comprises patients referred for non-inflammatory diseases of the locomotor system who are all active members of the workforce and whose vocational status is threatened by their disease. Intervention consisted of sociomedical examination, multidisciplinary assessment and individual sociomedical rehabilitation plans. The study shows that intervention was an important instrument in the process of clarifying patients' future maintenance situation as assessed 1 year after intervention (relative risk (RR) = 1.2 (CI 1.0-1.5)). The effect was particularly prominent among well-educated women. A non-significant effect was established for vocational status in general (RR = 1.1 (CI 0.8-1.4)). This effect was significant and positive for well-educated patients with a short-term sick leave (maximum 6 months). The verified effect of early sociomedical intervention in the secondary healthcare sector warrants the permanency of routine intervention.

Adolescent↗
PubMed2000

Prolonged in vitro cultivation of Ichthyophthirius multifiliis using an EPC cell line as substrate.

The ciliate Ichthyophthirius multifiliis, which normally requires a fish host to develop from the theront stage to the trophont stage, was cultivated in vitro for part of its life cycle. Experiments were conducted using a laboratory strain of the parasite originally isolated from rainbow trout Oncorhynchus mykiss in a Danish trout farm. Theronts escaping from tomontocysts were kept in water, cell culture media (E-MEM or L-15), or cultures of EPC (Epithelioma Papulosum Cyprini) cells in plastic tissue culture dishes (Nunc multidish plates). In addition, a 2-compartment system, with water separated from tissue culture media by a monolayer of EPC cells on an Anopore Tissue Culture Insert (mimicking the fish epidermis) was tested as an experimental habitat for the parasite. Theronts transformed into trophonts in all treatments except in water alone. However, development was accelerated in wells containing EPC cells, and survival and growth of trophonts were significantly increased compared to water or tissue culture media alone. Further, the 2-compartment system allowed superior performance of the parasites (attachment of parasites to cells and growth from 36 to 46 microm). In all experiments it was found that the presence of host factors (mucus and serum) stimulated parasite development.

Animals↗
PubMed2000

Age-dependent occurrence of the intestinal ciliate Balantidium coli in pigs at a Danish research farm.

A cross sectional study of the prevalence and intensity of Balantidium coli in pigs was carried out on a Danish research farm. The prevalence of B. coli infection increased from 57% in suckling piglets to 100% in most pig groups > or = 4 weeks old. The mean number of cysts per gram faeces (CPG) of pigs aged 12 weeks and younger were < or = 206, whereas pigs aged 28 weeks and > 52 weeks had significantly higher counts of > or = 865 CPG. Although some lactating sows had very high CPG's, no significant differences in CPG could be detected between the intensities of pregnant sows, lactating sows and empty and dry sows. No human cases of B. coli infection have been published in Denmark though it is zoonotic.

Age Factors↗
PubMed2000

In vitro interactions between epithelial cells and Gyrodactylus derjavini.

Skin responses of fish to various parasites have been shown to involve various immunologically competent cells producing factors which guide the reactions of epithelial cells. However, the present study has demonstrated that a monoculture of epithelial cells has the ability to encapsulate and partially degrade ectoparasites without involvement of leukocytes. The ectoparasitic monogeneanGyrodactylus derjavini was kept on a monolayer of Epithelioma Papulosum Cyprini (EPC) cells in 24-well multidishes supplied with tissue culture medium. Gyrodactylus derjavini did not reproduce but survived an incubation period of up to139h in the system. Due to sterile conditions, dead gyrodactylids were not subjected to microbial degradation and remained intact for several weeks. However, at 40 days G. derjavini was overgrown by EPC-cells and became partly degraded during the following 15 days. Analysis of enzyme reactivity in EPC-cells showed reactions for ten enzymes including esterases, amidases, phosphatases and phosphohydrolases. No marked differences for the ten enzymes between cell cultures with and without the ectoparasites were found but it cannot be excluded that some of these enzymes took part in parasite degradation. The study showed the in vitro capability of epithelial cells to interact, encapsulate and degrade G. derjavini without the involvement of leukocytes. This response probably is non-specific and will not exclude that various immunocompetent cells and their products normally optimize and accelerate elimination of invading parasites in vivo.

Animals↗
PubMed1996

[Sick leave for pregnant women in the municipality of Fjend 1987-1990].

All of 417 pregnancies in 1987-1990 in a rural community were retrospectively evaluated with emphasis on age, parity, previous spontaneous or induced abortion, occupation during pregnancy and sick leave from work. No difference was found in prevalence of sick leave between the employed women and the unemployed. Thirty-five percent of the women experienced sick leave at some time during pregnancy. The greatest single diagnostic group was pelvic insufficiency, which accounted for 33.5% of all days of sick leave up to the 32nd week of gestation. The incidence of pelvic insufficiency was high: 76 in 1000 deliveries. This may in part be due to a change in diagnostic criteria. Logistic regression analysis revealed that being a multipara was associated with a significantly higher risk of sick leave in the present pregnancy. Furthermore, being employed as a nurse, a shop assistant, a seamstress or a factory worker was associated with a significantly higher risk of sick leave during pregnancy in comparison with employment as a secretary. When investigating relationships between occupational conditions and the outcome of pregnancy, sick leave during pregnancy because of the same conditions may interfere significantly.

Adult↗
PubMed1992

Job stress and adverse outcome of pregnancy: a causal link or recall bias?

A case-base study in a population of 214,108 commercial and clerical female workers in Denmark during the period 1983-1985 investigated whether increasing job stress, defined as increasing job demands and decreasing job control, increased the risk of an adverse outcome of pregnancy. Information on the cohort, the outcome of 24,362 pregnancies, was obtained by linkage with nationwide health registers. Six case groups were selected: 1) 2,248 spontaneous abortions, 2) 209 stillbirths or deaths within the first year of life, 3) 661 infants with congenital malformations, 3) 593 preterm deliveries, 4) 587 infants with term low birth weights, 5) 988 infants with light-for-date birth weights, and 6) a random sample of 2,252 pregnancies that constituted the reference group. Information on exposure was obtained by mailed questionnaire. When dichotomized scales on data concerning job demand and control were used, there was an increased relative risk of spontaneous abortion (odds ratio = 1.28, 95% confidence interval (CI) 1.05-1.57) and term low birth weight (odds ratio = 1.46, 95% CI 1.05-2.04) for women experiencing high job stress. For the other case groups, the odds ratios were as follows: congenital malformation, 1.23 (95% CI 0.93-1.63); preterm delivery, 1.03 (95% CI 0.77-1.39); light-for-date birth weight, 1.08 (95% CI 0.83-1.40); and stillbirth/death within the first year of life, 1.42 (95% CI 0.90-2.24). No substantial response bias was found. When occupational titles were used as an exposure matrix, no increased risk was found, except for term low birth weight. Recall bias is one possible explanation. Thus, the results must be interpreted with caution.

Adolescent↗
PubMed1992

Fetal growth, preterm birth and infant mortality in relation to work with video display terminals during pregnancy.

Through register linkage between a trade union file and public health registers 24,352 pregnancy outcomes were selected from a source population of 214,108 commercial and clerical employees. In a case-base study including all recorded cases and a randomly selected base sample, the potential effect of video display terminal (VDT) use in pregnancy on the risk of low birthweight, preterm birth, light weight for delivery date, stillborn, perinatal death, and infant death was investigated. Data on VDT use and potential confounders were collected from postal questionnaires sent to 6312 women and 426 employers. The rate ratio for women exposed to any degree of use was 0.88 for low birthweight [95% confidence interval (95% CI) 0.67-1.16], 1.11 for preterm birth (95% CI 0.87-1.47), 0.99 for light weight for delivery date (95% CI 0.80-1.21), 0.73 for stillborn (95% CI 0.36-1.48), 1.10 for perinatal death (95% CI 0.62-1.94), and 0.20 for infant death (95% CI 0.04-1.03). In conclusion, this investigation did not show an increased risk of the studied adverse pregnancy outcomes among women with VDT use.

Adolescent↗
PubMed1992

Fecundity and the use of video display terminals.

The association between prolonged waiting time to pregnancy and the use of a video display terminal (VDT) was investigated among commercial and clerical employees in Denmark. Information on 24,352 pregnancies was obtained through register linkage with two national registers. A random sample of 2252 pregnancies was drawn, and the women were asked for information on waiting time to pregnancy, occupational exposures, and life-style factors. The overall exposure to a VDT indicated a slightly increased association with prolonged waiting time to pregnancy. The relative risks for waiting more than one year were 1.23, 0.77, and 1.61 for the women who worked with a VDT for 1-10, 11-20, and > or = 21 h per week, respectively. Only the last relative risk was statistically significant. The results could be explained by methodological shortcomings such as recall bias or confounding by alternative factors that might affect time to pregnancy, or simply by the lack of statistical power.

Adolescent↗
PubMed1990

Congenital malformations among children of women working with video display terminals.

In a case-base study among 214,108 commercial and clerical employees in Denmark the potential effect of the use of video display terminals on the risk of congenital malformations in pregnancy was investigated. The study base was identified by means of register linkage of the Medical Birth Register and the National Register of In-Patients. In the source population 24,352 pregnancy outcomes were registered, 661 of which with congenital malformations entered the case group, and a base sample of 2252 pregnancies was drawn. Data concerning the use of video display terminals, job stress, ergonomic factors, exposure to organic solvents, and life-style factors were obtained from postal questionnaires. The results of this study did not support the hypothesis that the use of video display terminals during pregnancy is associated with an increased risk of congenital malformations.

Adolescent↗
PubMed1990

Spontaneous abortion among women using video display terminals.

This case-base study with a source population of 214 108 commercial and clerical workers investigated the risk of adverse pregnancy outcome among women working with a video display terminal (VDT) in Denmark. A subpopulation was obtained by register linkage between a trade union membership file, the Medical Birth Register, and the National Register of In-Patients. In two years 24,352 pregnancy outcomes were registered, 2248 spontaneous abortions were recorded, and a base sample of 2252 pregnancies was randomly selected. Data on VDT use, job stress, ergonomic factors, and life-style factors were collected with questionnaires sent to 6212 women and 426 employers. There was no increased risk of medically verified spontaneous abortion among women with VDT use. The relative risk for women exposed to any degree of use was 0.94 (95% confidence interval 0.77-1.14). Ergonomic work load and job stress were not confounders.

Abortion, Spontaneous↗