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Biomedical subjects

P Henriksen

Publications and source records attributed to P Henriksen.

At least 19 recordsLinked to original sources
PubMed1997

Seasonal variations in microcystin contents of Danish cyanobacteria.

One hundred ninety-eight of 296 phytoplankton net samples, collected from Danish fresh waters during 1993-1995, contained microcystins when analyzed by high-performance liquid chromatography (HPLC), and the seasonal variations in microcystin contents were examined. Three genera, Anabaena, Microcystis, and Planktothrix, with microcystin-production potential were found. The highest percentage of the samples dominated by Anabaena and Microcystis was found in June-July and July-November, respectively, and those by Planktothrix in May and October-November. The highest microcystin contents were found in samples collected in July and September. When pooling all samples by month of collection, no major differences in mean toxin contents were seen in samples collected from May through November, with the exception of slightly higher microcystin contents in September and October. The frequency of samples (all samples grouped by month of collection) with detected microcystins ranged from 62% in July (n = 116) to 86% in May (n = 7). Variations in toxin profiles were found between 5 lakes sampled several times during 1993-1995, and in addition, quantitative and qualitative seasonal changes in microcystin content accompanied species composition changes in 3 of these lakes. Consistent blooms dominated by single species were characterized by more or less constant toxin profiles but variable toxin concentrations. Analysis of 6 samples from Lake Bryrup Langsø 1995 by enzyme linked immunoabsorbent assay and HPLC revealed 1-70 and 0-737 micrograms microcystins/g dry wt, respectively. The discrepancy between the two detection methods may be attributed to the types of microcystin variants present, emphasizing the possible influence of seasonal variations in toxin profiles on the quantification of microcystins.

Carcinogens↗
PubMed1997

Detection of an anatoxin-a(s)-like anticholinesterase in natural blooms and cultures of cyanobacteria/blue-green algae from Danish lakes and in the stomach contents of poisoned birds.

Ten natural bloom samples of cyanobacteria from the Danish lakes Knud sø (5), Ravn sø (4), and Salten Langsø (1) collected during 1993-1995 were assayed for toxicity by mouse bioassay, for acetylcholinesterase inhibiting activity by a colorimetric method, and for microcystins by enzyme-linked immunosorbent assay. In the mouse bioassay, seven samples were neurotoxic, two were non-toxic and one gave a protracted toxic response. One of the non-toxic and the single protracted toxic sample both contained anticholinesterase activity equivalent to 4 micrograms anatoxin-a(s) g-1. The neurotoxic samples contained equivalents to 20-3300 micrograms anatoxin-a(s) g-1. The highest anticholinesterase activities (equivalent to 2300 and 3300 micrograms anatoxin-a(s) g-1, respectively) were found in samples collected from Lake Knud sø in connection with bird-kills in 1993 and 1994. Small amounts of microcystins (0.1-0.9 microgram g-1) were detected in all samples but one. All Lake Knud sø and Lake Ravn sø samples were dominated by Anabaena lemmermannii, and the Lake Salten Langsø sample by several species of Anabaena. Gel filtration profiles indicated similarity between the toxic component from the Lake Knud sø 1994 bloom with registered bird-kills and anatoxin-a(s) isolated from Anabaena flos-aquae NRC-525-17. Anticholinesterase-producing cultures of A. lemmermannii were isolated from the Lake Knud sø 1993 bloom. These laboratory cultures produced anatoxin-a(s) equivalents of 29-743 micrograms g-1. Other cultures of A. lemmermannii isolated from Lake Knud sø and Lake Ravn sø were hepatotoxic or non-toxic. Dead birds collected from Lake Knud sø during the neurotoxic 1993 Anabaena bloom possibly died from cyanobacterial toxicosis. The stomach contents contained colonies and single trichomes of Anabaena, and anticholinesterase activities equivalent to 2.1-89.7 micrograms anatoxin-a(s) kg-1 body weight and microcystins (53-95 ng kg-1) were also detected.

Acetylcholinesterase↗
PubMed1997

Confirmation of anatoxin-a(s), in the cyanobacterium Anabaena lemmermannii, as the cause of bird kills in Danish lakes.

Cyanobacterial blooms were implicated in bird kills at lakes in Denmark in July 1993 and June-July 1994. These blooms were dominated by Anabaena lemmermannii and were shown to contain a neurotoxin with anticholinesterase activity. In this study, the toxin was isolated by mouse lethality guided column chromatographies from the field sample collected at Lake Knud sø in 1993. Various spectroscopic data indicated that the toxin was anatoxin-a(s), an irreversible anticholinesterase, first reported in Anabaena flos-aquae. Chemical detection of the same toxin in cultured A. lemmermannii also confirmed this species as the cause of the deaths of the wild birds.

Anabaena↗
PubMed1997

Toxoplasmosis in a colony of New World monkeys.

In a colony of New World monkeys five tamarins (Saguinus oedipus, Saguinus labiatus and Leontopithecus rosal. rosal.), three marmosets (Callithrix jacchus and Callithrix pygmaea) and one saki (Pithecia pithecia) died suddenly. The colony comprised 16 marmosets, 10 tamarins and three sakis. The main pathological findings were necrotic lesions in the lung, the intestine, and the liver. Histopathologically T. gondii parasites were observed in organs from the tamarins and the marmosets but not in the saki. Some considerations on epidemiology are presented. Preventive measures were directed against the bottom layer of the cages, on cockroach extermination, and on freezing of raw meat.

Animal Feed↗
PubMed1996

Evaluation of an immunoradiometric assay for thyrotropin in serum and plasma samples of dogs with primary hypothyroidism.

A commercially available immunoradiometric assay was used to measure the thyrotropin (TSH; thyroid-stimulating hormone) concentration in the serum and plasma of 23 dogs. The basal concentration in five dogs with histologically confirmed primary hypothyroidism (median 0.18 microg/l, range 0.16-0.72 microg/l) was slightly, but not significantly, higher than that in 13 clinically healthy dogs (median 0.09 microg/l, range 0.06-0.34 microg/l). The TSH values in 11 euthyroid dogs with various dermatological diseases (median 0.09 microg/l, range 0.05-0.53 microg/l) were significantly lower than in the hypothyroid dogs, but there was considerable overlap. The assay alone was therefore not capable of giving a firm diagnosis.

Animals↗
PubMed1994

Seroprevalence of Toxoplasma gondii in Danish farmed mink (Mustela vison S.).

One hundred and ninety-five mink sera randomly selected from 17 Danish mink farms were evaluated for the presence of Toxoplasma gondii antibodies in the latex agglutination test. Six (3%) sera contained T. gondii antibodies in titres of 1:64 or more. The estimated 3% prevalence means that 300,000 mink out of a total mink population of ten million might be infected with Toxoplasma gondii. This large number of possible sero-positive mink in Denmark indicates that there exists a potential risk of acquiring toxoplasmosis by pelting mink.

Agricultural Workers' Diseases↗
PubMed1994

Fatal toxoplasmosis in five cats.

Fatal toxoplasmosis was diagnosed in five of 155 cats necropsied in Denmark during a 2 year period, thus representing 3.2% of the necropsied animals. Lesions were dominated by scattered necrotic foci in liver and spleen. Toxoplasma gondii was demonstrated primarily by an immunoperoxidase technique. The clinical signs were rhinitis, conjunctivitis, dyspnoea and neurological malfunction. The relatively high prevalence indicates that clinical and fatal toxoplasmosis, naturally acquired, seems more frequently occurring among cats than is generally assumed.

Animals↗
PubMed1994

Effect of protein and fat content in feed on plasma alanine-aminotransferase and hepatic fatty infiltration in mink.

The effect of the content of protein and fat in the feed on the development of fatty infiltration of the liver in the period from weaning until pelting was measured in two groups of male scanblack mink (Mustela vision) fed 20% and 45%, respectively, of metabolizable energy (ME) from protein. Furthermore, plasma activity of alanine-aminotransferase and the content of specifically chosen clinical-chemical variables in the blood were measured. At pelting time in December, the liver weights were absolutely and relatively heavier to body weight and had a considerably higher fat content at 20% of ME from protein than at 45% of ME from protein. From August to pelting time, the activity of alanine-aminotransferase in plasma was higher at a low protein level than at a higher protein level in the feed. It is concluded that the content of protein and fat in the feed affects the incidence of hepatic fatty infiltration in mink. In the growth period, it is possible, based on plasma activity of alanine-aminotransferase, to select animals with histological fatty infiltration of the liver.

Alanine Transaminase↗
PubMed1994

A study on the predilection sites of Trichinella spiralis muscle larvae in experimentally infected foxes (Alopex lagopus, Vulpes vulpes).

Studies were carried out on the predilection sites of Trichinella spiralis muscle larvae in experimentally infected arctic foxes (Alopex lagopus) and silver foxes (Vulpes vulpes) reared in cages. The highest number of larvae per gram tissue was found in the muscles of the legs, eyes, diaphragm, and tongue. The 2 fox species showed no significant differences with regard to predilection sites.

Animals↗
PubMed1993

The common frog (Rana temporaria) as a potential paratenic and intermediate host for Angiostrongylus vasorum.

Common frogs (Rana temporaria) were exposed either to third-stage larvae (L3) or to first-stage larvae (L1) of Angiostrongylus vasorum. Following exposure to L3, viable larvae could be detected in the frogs for at least 2 weeks. Following exposure to L1, the frogs developed viable L3 in their tissues within 30 days. In a test of the infectivity of these larvae, one fox was fed frogs previously infected with L3 and another fox was fed frogs previously infected with L1. On autopsy it was found that adult A. vasorum populations had been established in both foxes. Thus, it could be concluded that frogs can act not only as paratenic hosts but also as intermediate hosts for A. vasorum.

Angiostrongylus↗
PubMed1993

Experimental infection with Toxoplasma gondii in farmed mink (Mustela vison S.).

Live Toxoplasma gondii tissue cysts (Strain 119) were administered orally to five mink (Mustela vison S.) and five mink were inoculated with a suspension of ultrasonicated Toxoplasma gondii trophozoites (RH-strain). Seroconversion was observed in all animals administered live T. gondii cysts indicating that infection was established. Likewise seroconversion was observed in three out of four animals administered ultrasonicated T. gondii trophozoites. Faecal shedding of oocysts of T. gondii was not demonstrated in any of the infected animals. Histologically chronic meningitis with calcification was seen in all animals. Cerebral T. gondii tissue cysts were detected in four animals administered live tissue cysts. The study demonstrates that mink can be experimentally infected with T. gondii, thus representing a potential infection source for man, when considering the pelting procedure.

Animals↗
PubMed1993

Studies on manifestations of canine distemper virus infection in an urban dog population.

An upsurge of canine distemper was recognized at the beginning of 1991 in the urban dog population of the Copenhagen area. The outbreak had the characteristics of a virulent morbillivirus introduction in a partly immune population, where the disease primarily was manifested in young individuals. Testing of single serum samples for the presence of canine distemper virus (CDV) IgM antibodies using an IgM ELISA confirmed current and recent CDV infections in an urban dog population, where the use of attenuated CDV vaccines was widespread. In 49 out of 66 sera from clinical cases suspected of canine distemper we detected CDV IgM antibodies, as compared to the detection of viral antigen by indirect immunofluorescence in 27 of 65 specimens of conjunctival cells. The antigenic make-up of isolates from acute and subacute clinical cases was investigated with a panel of 51 monoclonal antibodies directed against CDV and the related phocine distemper virus. The isolates exhibited an homogeneous reaction pattern and shared overall antigenic characteristics of the CDV prototype. The majority of cases were diagnosed among unvaccinated dogs and individuals with unknown or obscure vaccination record. However, severe clinical cases were also diagnosed in vaccinated individuals.

Animals↗
PubMed1992

Disseminated histoplasmosis in a badger (Meles meles) in Denmark.

We report the first case of disseminated histoplasmosis in an animal in Scandinavia. Yeast cells compatible with those of Histoplasma capsulatum var. capsulatum were found in the skin, liver, spleen, a kidney, and a lymph node of a wild badger (Meles meles). The diagnosis was confirmed by electron microscopy and immunofluorescence staining of the yeast cells in tissue sections.

Animals↗
PubMed1992

The fox (Vulpes vulpes) as a reservoir for canine angiostrongylosis in Denmark. Field survey and experimental infections.

Until recently, Angiostrongylus vasorum was not considered to be an endogenous Danish parasite, since demonstration of this worm had been confined to necropsy findings in 2 dogs, both of which had visited France. During the last 2 years, however, clinical cases have been diagnosed among a considerable number of Danish dogs, none of which had ever been outside Denmark. All these cases have occurred north of Copenhagen, where an endemic focus seems to exist. In this field survey A. vasorum was found for the first time in wild Danish red foxes. Furthermore, experimental infections showed that the parasite can be transferred between foxes and dogs. Consequently, the wild fox population must be considered a potential reservoir for transfer of A. vasorum to domestic dogs.

Angiostrongylus↗
PubMed1991

The seal death in Danish waters 1988. 1. Pathological and bacteriological studies.

During the seal epizootic in Danish waters in 1988 a total of 81 adult seals were necropsied. The cause of death was suppurative bronchopneumonia complicated by pleurisy. Histologically, an interstitial pneumonia with cytoplasmatic inclusion bodies typical of canine distemper was identified in many of the seals. The condition was in many cases complicated with a secondary infection with Bordetella bronchiseptica.

Animals↗
PubMed1988

Polycystic disease of the kidney in related mink.

Polycystic kidneys in young related mink kits were seen on a mink farm in 1983 (4 kits) and 1984 (6 kits). The kits showed retarded growth and locomotor abnormalities leading to death in the 1983 kits at the age of 4 months. The renal cysts involved the collecting tubules; there was vacuolization and focal hyperplasia of the epithelium. Other organs were normal. The data available for the condition in mink are insufficient as yet to explain the mode of inheritance.

Animals↗