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Biomedical subjects

J Andreassen

Publications and source records attributed to J Andreassen.

At least 37 records · Page 2Linked to original sources
PubMed1989

Repair of Hymenolepis diminuta after complement-mediated damage.

Seven and 56-day-old Hymenolepis diminuta were exposed to complement by incubation in 50% normal rat serum (NRS) in modified Hanks' saline. Ultrastructural studies revealed that the scolex/neck region remained relatively intact whilst in the strobila region microthrix denudation and loss of distal cytoplasm were observed. When complement-mediated damaged worms were incubated in vitro in 50% heat-inactivated normal rat serum (hiNRS) plus M199 or implanted into the duodenum of NMRI mice repair occurred, although destrobilated parasites were only found in vivo. The regions undergoing repair contained tegumental protrusions, vesicles, large electron-lucent areas and large quantities of lipid. Microtriches were formed parallel to the parasite surface and were raised into a perpendicular position. It is suggested that the regenerative process exhibited after complement-mediated damage does not mimic totally the embryological development of the surface layer.

Animals↗
PubMed1989

Stage-specific antigens of Hymenolepsis microstoma recognized in BALB/c mice.

Antigenicity of eggs (oncospheres), cysticercoids and adults (with immature segments only) of the bile duct tapeworm Hymenolepsis microstoma was analysed using immunoblotting techniques and indirect immunofluorescent antibody (IFA) techniques with immune sera of BALB/c mice (i) infected with different doses of cysticercoids, (ii) during patent or prepatent infection with the lumen phase of the parasite or (iii) sensitized with live or dead eggs. Antibody responses detected by IFA test and immunoblotting showed that antigenicity of eggs (oncospheres) differed from that of cysticercoids and adults. Single worm infections were sufficient to stimulate antibody responses. Mice which had patent infection showed strong antibody responses to all three (egg (oncosphere), cysticercoid, adult) antigens, while mice given two prepatent infections showed some antibody responses to cysticercoid and adult antigens only. Although the normal intermediate hosts of this parasite are arthropods, antibodies to some major egg (oncosphere) antigens were produced in mice given eggs of this parasite orally, either through inoculation of eggs or ingestion of faeces contaminated with eggs. Antibodies were not produced in mice dosed with non-viable eggs. The results are consistent with the hypothesis that cestode parasites express phase- (or stage-) specific antigens.

Animals↗
PubMed1986

Echinostoma revolutum: resistance to secondary and superimposed infections in mice.

A complete or almost complete resistance (94-100%) to a superimposed Echinostoma revolutum infection existed in mice harboring 20-, 30-, and 40-day-old infections in the range of 2-4 to 30-35 worms, but no resistance was found at challenge Day 10. A similar high level of resistance (85-100%) also existed in mice for at least 6 weeks after natural expulsion of a primary 6 metacercarial infection and for at least 5 weeks after anthelmintic termination of a 30-day-old 20 metacercarial infection. Thymus-deficient nude mice failed to develop resistance to a superimposed infection, and the resistance in normal mice was inhibited by corticosteroid treatment. These findings are all in favor of a host immune response being responsible for the resistance against both a secondary and a superimposed infection. Nearly all the worms of a superimposed infection were, in resistant mice, expelled prior to 24 hr following infection (rapid expulsion), and the few worms circumventing this early expulsion persisted for at least 8 days. Newly excysted juvenile worms implanted intraduodenally into resistant mice were rejected to the same degree as juvenile worms from an oral metacercarial infection indicating that the newly excysted juvenile worms are the target of the host immune response. However, 7-day-old worms implanted intraduodenally into resistant mice survived indicating that adaptation to the host immune response had occurred. In conclusion, this host-parasite model is an example of concomitant immunity because the immunological mechanism responsible for the expulsion of the superimposed infection had no effect on the number of primary worms present.

Adrenal Cortex Hormones↗
PubMed1985

Hymenolepis diminuta: a comparison between young developing, and small, destrobilated worms in the rat intestine.

Newly in vitro excysted tapeworms of Hymenolepis diminuta (Cestoda, Cyclophyllidea), 1- to 3-day-old worms and destrobilated worms from rat intestines were investigated by means of light microscopy (LM) and scanning electron microscopy (SEM). It was found that the scolex of 1- and 2-day-old worms had shallow suckers with smooth brims, while 3-day-old and older worms, including destrobilated worms, had deep suckers with puckered brims. The posterior end of 1- and 2-day-old worms had a central cone-shaped structure not present in 3-day-old and older, or destrobilated worms. The repairing of the posterior end and the protonephridial system after excystation or destrobilation was much the same. Tissue remnants moved into the centre of the posterior end, resulting in an indentation with a pore to the exterior. The indentation and its pore became connected to the emptying canals of the protonephridial system, i.e. they developed into the excretory bladder and pore respectively.

Aging↗
PubMed1982

Immunological and histopathological reactions of the rat against the tapeworm Hymenolepis diminuta and the effects of anti-thymocyte serum.

Anti-thymocyte-serum (ATS) treated Wistar rats infected with 100 cysticercoids of the rat intestinal cestode Hymenolepis diminuta showed a delayed destrobilation and expulsion of the worms compared with saline-treated infected rats. This result strengthens previous evidence of an immunological nature of the destrobilation and expulsion in lumen-dwelling cestodes--even in their most susceptible hosts. The migration of the worms in the small intestine during the first 20 days of a primary 100-worm infection is described and the anterior migration of the destrobilated worms to the first 10% of the pylorus is emphasized and compared with similar migrations of the nematode Nippostrongylus brasiliensis in the rat. No serum antibodies were detected using passive cutaneous anaphylaxis and the indirect immunofluorescence test, although the thymus-independent areas of the mesenteric lymph nodes showed an increase in pyroninophilic cells. In the small intestine, no response to the tapeworm infection could be detected in pyroninophilic cells and globule leucocytes, but mast cell and eosinophilic cell numbers were increased in the saline-treated infected rats. Although the host responses to H. diminuta are shown to be thymus-dependent, the possibility of thymus-independent activity in the host reactions cannot be ruled out.

Animals↗
PubMed1980

Immunologically mediated rejection of Hymenolepis diminuta by its normal host, the rat.

The adult tapeworm, Hymenolepis diminuta, living in the lumen of the intestine of its normal rat host was shown to sensitize the intestine. The growth of worms in a secondary infection, given 8, 23, or 41 days after the primary infection had been removed by anthelmintic treatment, was 0.5, 3, and 25%, respectively, of that in the control worms. Thus, there is a strong initial resistance to a challenge infection, but this resistance weakens fifty-fold between days 8 and 41 postinfection. Even primary infections of five worms, which would have survived indefinitely if not expelled by anthelmintics, depressed the growth by over 80% of secondary infections given 8 days later. Rats given a light primary infection manifested their sensitivity only by depressing the growth of challenge worms, but in strongly sensitized rats, worm growth was stunted severely (or the worms destrobilated), partial worm expulsion occurred, and the remaining worms migrated to a more anterior position in the intestine. We suggest that the rapid waning of memory indicates that the protective mechanism evoked in the intestine has as its primary biological function the limitation of the number of worms that can accumulate in the intestine in concurrent infections, not the prevention of reinfection after the loss of worms from previous infections.

Animals↗
PubMed1975

Some influences of population density on Hymenolepis diminuta in rats.

When measured 56 days postinfection the length, wet weight and dry weight of Hymenolepis diminuta were all found to decrease with increasing number of cysticercoids given up to 20. The mean position of the worms in 10, 12 and 20 worm infections is significantly posterior to that of 1, 2 and 5 worm infections and the worms are attached over a wider area of the intestine. Egg production by the worms was followed up to day 56 postinfection; the number of eggs produced per worm and even per rat decreased with increasing population density. Thus the best way to get most eggs and to maintain the parasite in the laboratory is to have rats infected with only one tapeworm. Rats given 1-20 cysticercoids showed a mean recovery of 100-65%, while rats given 40-200 cysticercoids showed a mean recovery ranging from 13 to 2%. In addition to 'normal' worms, defined as worms greater than 10 mm, small, most probably destrobilated, worms were found. In the 50 and 100 cysticercoid infections, worm recoveries were, respectively, 8% 'normal', 16% small, and 2% 'normal', 5% small. From the significantly lower recovery from heavy infections it is concluded that a deleterious factor is operating during the 8 weeks after the infection.

Animals↗