Toxoplasmosis in Sheep

The epidemiology of toxoplasmosis in sheep was studied during a period of 31/2 to 6 years in 4 flocks in which abortions from the infection previously had occurred. The epidemiological pattern indicated that a heavy contamination of the environment may persist for about 2 years. Even in flocks with an apparently normal reproductive performance, toxoplasmosis may cause barrenness, abortion or delivery of dead lambs in 1–2 % of the breeding ewes. The prevalence of infected sheep increased with the age. The incidence of infection was significantly lower in 6–12 months old lambs than in mature ewes. The incidence of infection was higher on lowland pastures than on mountain pastures in not populated areas. On lowland pastures the incidence of infection was lower during the summer than during the winter. kw|Keywords|k]toxoplasma infection; k]epidemiology; k]sheep {fn1|This work was supported by grants from the Norwegian Research Council for Science and for the Humanities.}     

Enhanced cancer cell invasion caused by fibroblasts when fluid flow is present

Biomechanics and Modeling in Mechanobiology - It has been demonstrated that interstitial fluid (IF) flow can play a crucial role in tumor cell progression. Swartz and collaborators (Cancer Cell 11:...     

Live and killed vaccines against toxoplasmosis in mice

Mice were immunized with live organisms of the different stages (i.e., tachyzoites, bradyzoites, or sporozoites) of Toxoplasma gondii, or with killed tachyzoites with or without adjuvants. The adjuvants used were liposomes, anhydrides of myristic or lauric acid, levamisole and Freund's complete or incomplete adjuvant. The following strains of T. gondii were used: RH, M-7741, the nonpersisting, temperature-sensitive mutants ts-1, ts-4, or ts-5, and the "back mutant" of ts-1 (Pfefferkorn and Pfefferkorn, 1976). The protection afforded was measured by challenge with the pathogenic M-7741 strain. Killed tachyzoites alone, or with adjuvants, offered only slight protection against challenge with M-7741 and no protection against challenge doses that were lethal to all control mice. Chronic infection and live nonpersisting vaccines conveyed a strong immunity to challenge, except strain ts-1. Because it was less pathogenic and did not require chemoprophylaxis, strain ts-4 best fulfilled the requirements for a good vaccine; its effect in hosts other than the mouse remains to be determined. The immunity induced by tachyzoites, bradyzoites, or sporozoites appeared equally strong when challenged with sporozoites.     

Toxoplasmosis in Sheep

The presence of Toxoplasma gondii in the diaphragm was correlated with the dye test titres in 174 sheep. In 94 of these the presence of the parasite was also correlated with the haemoglobin (Hb) type. T. gondii was recovered from 3 % of the sheep with titres < 1/16, compared with 30 % of those with titres 1/16 and 70 % of those with titres ≥ 1/32. The results indicate that the distinction between serologically positive and negative individuals at a final serum dilution of 1/16 is justified. Some evidence was found that the parasite is easier to recover from dye test positive mature sheep than from dye test positive lambs. Of the 174 sheep, 143 were examined at random among 186 sheep culled or cast for age during a 4-year period from 1 flock in which the prevalence of Toxoplasma antibodies was representative for flocks in the southern Norway, and T. gondii was recovered from 53 (37 %) of these. It was concluded that 10—15 % of the lamb carcases and 25—37 % of the carcases from mature sheep in this country have T. gondii in their muscles detectable by the peptic digestion technique. A possible genetical influence on the infection was indicated by the higher frequency of recoveries of T. gondii from sheep with Hb type B than from sheep with the Hb types A or AB, but the number of individuals with Hb type B was too small to demonstrate statistically significant differences. The epidemiological importance of infected sheep carcases is discussed.     

Foetal loss in dairy goats: function of the adrenal glands, corpus luteum and the foetal-placental unit.

To investigate the causes and mechanisms of foetal loss in Norwegian dairy goats, blood parameters in 40 goats that lost foetuses were compared with those in 40 goats that experienced a normal pregnancy. High mean levels of 15-ketodihydro-PGF2alpha, and low mean levels of oestrone sulphate throughout pregnancy were associated with foetal loss. The mean oestrone sulphate level was low before abortion, and the distinct peak that occurred at parturition in the control goats was not observed in connection with abortion. Association of other blood parameters with foetal loss was not detected. Infectious agents and toxins did not appear to be major causes of foetal loss in this study. The normal level of progesterone and cortisol in goats with foetal loss indicated that the function of the corpus luteum and adrenal glands, respectively, were not disturbed. The rapid decline in progesterone level associated with foetal loss may therefore be a result, rather than the cause, of foetal death. The lowered level of oestrone sulphate and elevated level of 15-ketodihydro-PGF2alpha in goats with foetal loss clearly indicated that the endocrine foetal-placental function was disturbed.