Plasma and Tissue Levels of Trimethoprim in The Rainbow Trout,Salmo Gairdneri,After Absorption From Fresh and Salt Water

This is a comparative study of uptake of trimethoprim from 1) fresh water, 2) salt water after 7 days of adaption and 3) salt water without previous adaptation. The rate and extent of absorption were found to vary significantly. The salt water adapted group reached a plasma concentration of approx. 1 µg/ml after 10 h, the unadapted salt water group after 24 to 48 h and the fresh water group did not reach this concentration. The results are discussed in relation to the non-ionic diffusion theory and to the alterations taking place in euryhaline species of fish during adaptation to salt water.     

Direct high-resolution genotyping of Toxoplasma gondii in arctic foxes (Vulpes lagopus) in the remote arctic Svalbard archipelago reveals widespread clonal Type II lineage

Characterization of Toxoplasma gondii genotypes in hosts living in remote, isolated regions is important for elucidating the population structure and transmission mode of this parasite. Herein, we report the results of direct genotyping of T. gondii in brain tissue of arctic foxes (Vulpes lagopus) from the remote, virtually cat-free, high arctic islands of Svalbard. DNA extracts from brains of 167 seropositive arctic foxes (including four cases of fatal toxoplasmosis) and 11 seronegative arctic foxes were genotyped at 10 loci (SAG1, SAG2, SAG3, BTUB, GRA6, L358, c22-8, c29-2, PK1, and Apico) using the polymerase chain reaction-restriction fragment length polymorphism method. Of the 167 samples from seropositive foxes (including toxoplasmosis cases), 31 were genotyped at all 10 loci and 24 were genotyped at four to nine loci. To ensure confidence in T. gondii strain genotyping, samples for which less than four loci were genotyped were not considered positive. None of the 11 samples from seronegative foxes was positive for the 10 markers. Of the 55 samples that genotyped positively, 46 were of the Type II strain, 7 were of the Type III strain, and 2 were of atypical T. gondii strains. Five representative samples of the three genotypes were sequenced at loci SAG2, SAG3, GRA6, PK1, and UPRT-1. The DNA sequences confirmed the genotyping results. This study shows that the archetype Type II T. gondii strain, which is most widely distributed in North America and Europe, also predominates in arctic foxes on the Svalbard archipelago. This suggests that the T. gondii at this location originate from continental Europe and that transmission may be mediated by migrating birds. This study highlights the significance of long-distance transport of T. gondii and demonstrates that high-resolution genotyping protocols are useful for direct genetic studies of T. gondii when isolation of live parasites is infeasible.     

Absorption from water as an alternative method for the administration of sulphonamides to rainbow trout, salmo gairdneri. The significance of the pKa value of the sulphonamides and the pH and salt content of the water.

The effect of variations in pH and salt concentration on the absorption by rainbow trout of sulphonamides from water was investigated. Two trials were carried out: 1) Absorption from fresh water of sulphanilamide (pKa 10.4) and sulphadimidine (pKa 7.4) at pH 4, 6, 8 and 10 over a period of 96 hrs., and 2) Absorption from fresh water and sea water (salinity approx. 31 ‰) of the same two sulphonamides at pH 6 and 8 over a period of 24 hrs. The degree of acetylation of the two sulphonamides in rainbow trout was investigated.     

Temperature Related Absorption and Excretion of Sulphadimidine in Rainbow Trout,Salmo Gairdneri

The main purpose of the present study was to see if a kinetic model and a computer program for characterizing the rate of uptake and clearance of chemicals in aquatic organisms (Biofac, OECD’s Chemicals Testing Programme) was applicable to pharmacokinetic studies in fish. The program seems suitable for such studies.The effect of temperature upon rate of absorption of sulphadimidine from medicated water and elimination of the same drug was investigated in rainbow trout. A rise in the temperature from 7° C to 14° C more than doubled the calculated rate constants of absorption and elimination. The biological half life (t_½ β) and the time to reach 90 % of steady state (t_{90% ss}) at 14° C were approximately half the values at 7° C.     

Arctic rabies--a review

Rabies seems to persist throughout most arctic regions, and the northern parts of Norway, Sweden and Finland, is the only part of the Arctic where rabies has not been diagnosed in recent time. The arctic fox is the main host, and the same arctic virus variant seems to infect the arctic fox throughout the range of this species. The epidemiology of rabies seems to have certain common characteristics in arctic regions, but main questions such as the maintenance and spread of the disease remains largely unknown. The virus has spread and initiated new epidemics also in other species such as the red fox and the racoon dog. Large land areas and cold climate complicate the control of the disease, but experimental oral vaccination of arctic foxes has been successful. This article summarises the current knowledge and the typical characteristics of arctic rabies including its distribution and epidemiology.     

Serosurvey for Toxoplasma gondii in arctic foxes and possible sources of infection in the high Arctic of Svalbard

Samples (blood or tissue fluid) from 594 arctic foxes (Alopex lagopus), 390 Svalbard reindeer (Rangifer tarandus platyrhynchus), 361 sibling voles (Microtus rossiaemeridionalis), 17 walruses (Odobenus rosmarus), 149 barnacle geese (Branta leucopsis), 58 kittiwakes (Rissa tridactyla), and 27 glaucous gulls (Larus hyperboreus) from Svalbard and nearby waters were assayed for antibodies against Toxoplasma gondii using a direct agglutination test. The proportion of seropositive animals was 43% in arctic foxes, 7% in barnacle geese, and 6% (1 of 17) in walruses. There were no seropositive Svalbard reindeer, sibling voles, glaucous gulls, or kittiwakes. The prevalence in the arctic fox was relatively high compared to previous reports from canid populations. There are no wild felids in Svalbard and domestic cats are prohibited, and the absence of antibodies against T. gondii among the herbivorous Svalbard reindeer and voles indicates that transmission of the parasite by oocysts is not likely to be an important mechanism in the Svalbard ecosystem. Our results suggest that migratory birds, such as the barnacle goose, may be the most important vectors bringing the parasite to Svalbard. In addition to transmission through infected prey and carrion, the age-seroprevalence profile in the fox population suggests that their infection levels are enhanced by vertical transmission.     

A Comparison of Serum Concentrations of Penicillin After Intramuscular Injection and Subcutaneous and Deep Injection into the Dewlap in Cattle

Using an aqueous solution of sodium benzyl penicillin as the model substance, a comparison was made in cattle between absorption after intramuscular injection, and after subcutaneous and deep injection into the dewlap.The duration of supposed therapeutically effective serum concentrations using the 2 dewlap routes was longer than for the intramuscular route, although maximum concentrations were lower. The applicability of injection into the dewlap, especially the subcutaneous route, is discussed in relation to intramuscular injection.     

Unique genetic features of canine adenovirus type 1 (CAdV-1) infecting red foxes (Vulpes vulpes) in northern Norway and arctic foxes (Vulpes lagopus) in Svalbard

Canine adenovirus type 1 (CAdV-1) is the aetiological agent of infectious canine hepatitis (ICH) in domestic dogs (Canis familiaris). In spite of the widespread use of vaccination, CAdV-1 continues to circulate in the dog population. Although a high number of serological screenings have indicated that CAdV-1 is widespread in fox species, little is known about the potential role of foxes as reservoirs of CAdV-1. Furthermore, very little data exist on the molecular features of this virus in foxes. To add to existing knowledge on CAdV-1 circulating in wild carnivores, tissue samples from CAdV-seropositive red foxes (Vulpes vulpes, n?=?10) from the northern mainland of Norway and arctic foxes (Vulpes lagopus, n?=?10) from the Svalbard archipelago, Norway, were investigated using a molecular approach to detect CAdV-1 DNA and important structural and non-structural genes of the detected viruses were sequenced and analysed. Amplicons characteristic for CAdV-1 were amplified from 14 out of 20 foxes (7 red foxes and 7 arctic foxes) and spleen and lymph node tissues resulted optimal targets for the viral DNA detection. The nucleotide sequences showed unique features that distinguished the viruses detected in this study from the CAdV-1 to date identified in wild carnivores and dogs. Greater attention should be given to genetically different CAdV-1 circulating in wild carnivores that may be transferred to dogs, potentially causing disease and reducing the effectiveness of available vaccines.

     

The distribution of 35S-sulfadiazine and 14C-trimethoprim in rainbow trout, Salmo gairdneri.

The distribution of ³⁵S-labelled sulfadiazine and ¹⁴G-labelled trimethoprim was studied in rainbow trout by use of whole body autoradiography and liquid scintillation. As compared to mammals, gastrointestinal absorption and elimination were slow. Accumulation in the skin and the uveal tract of the eye was observed for both drugs tested. The results also indicated that the bile was an important route of excretion. Considerable radioactivity was still present in the skin at 144 hr. survival time.