Spirochetes in periodontal disease in the dog: a review.

The importance and the role of spirochetes in periodontal disease is controversial since the means to study these particular bacteria are limited. Because of specific requirements for growth, spirochetes are difficult to culture. Spirochetes could have profound effects on the perpetuation of periodontal disease. A review of the literature related to spirochetes is described.     

Distribution and form of uranium-containing deposits in chickens treated with uranyl nitrate

The kidneys of chicks treated with uranyl nitrate were examined by electron microscopy. Most deposits of electron-dense material containing uranium were found in the lumina of distal tubules and collecting ducts of kidneys collected 12-24 hours post-treatment. Some deposits were present in extracellular spaces between adjacent cells. Only occasionally were deposits found intracellularly where they were associated with localized cellular degeneration. A generalized cellular degeneration over the whole kidney was seen 72-96 hours post-treatment, but this was not directly associated with the deposits of electron-dense material.     

Serologic diagnosis of infectious cyclic thrombocytopenia in dogs using an indirect fluorescent antibody test

An indirect fluorescent antibody test was used for detection of serum antibodies to the platelet-specific rickettsial organism that is the causative agent of infectious cyclic thrombocytopenia (ICT) in dogs. The test converted from negative to positive in 7 of 7 experimentally inoculated dogs. One of 2 attempts to recover the rickettsial agent of ICT from naturally occurring seropositive dogs, by blood inoculation of experimental dogs, was successful. Seemingly, the test did not detect antibodies to Ehrlichia canis, nor did a similar test, using E canis antigen slides, detect antibodies to the rickettsial agent of ICT. The rickettsial agent of ICT has been classified tentatively as E platys. When applied to sera from a group of healthy random-source dogs, the test revealed a relatively low (5%) occurrence of positive reactions. A higher occurrence of positive reactions (35%) was noticed in sera from a group of thrombocytopenic dogs from the University of Florida. A majority of these positive sera were also positive for antibodies to E canis. The highest occurrence of positive reactions was found (greater than 50%) in E canis-positive sera from dogs at the University of Florida, as well as from dogs from 9 other states.     

Hormonal and histological studies in a 61XXY bull.

A Friesian bull with bilateral testicular hypoplasia was diagnosed as having a pure 61XXY karyotype. The bull displayed normal sexual behaviour but was azoospermic. At 17 months, the animal's peripheral plasma androgen levels appeared to be lower than normal, and one testicle removed one month later showed small seminiferous tubules totally lacking in germ cells. The Leydig cell volume of this testis was well within the normal range but the tubule length was rather short. At 33 months of age an increase in peripheral plasma androgen levels was noted. In the remaining testis there had been both a considerable rise in Leydig cell volume and a fall in tubule length. These findings may be explained by the interaction of three factors; the effects of the abnormal karyotype, the increased maturity of the animal at 33 months and the reaction of the remaining testis to unilateral castration.     

Yersinia enterocolitica. Experimental pathogenicity for chinchilla.

An intragastric inoculation of approx. 2 × 10¹⁰ Yersinia enterocolitica cells killed chinchillas in three days in the case of four strains out of six tested. Because of the sensitivity of chinchillas to this bacterium, the test is useful for the evaluation of the virulence and invasiveness of Y. enterocolitica isolates. This animal model could also be used for studies on the mechanism of the infection.     

Plant growth substance action on lecithin and lecithin/cholesterol vesicles

The adsorption of some plant growth regulating compounds onto lecithin and equimolar lecithin/cholesterol vesicles and the effect of these substances on the rate of chloride/nitrate and sodium/potassium ion exchange across the vesicular membranes have been examined. On comparing the binding of 2,4-D, 2,6-D, 2,4,5-T and IAA to lecithin vesicles in solution at various pH values it is found that the unionised form of these acids is bound very much more strongly than the ionised form. Compounds having relatively low oil/water partition coefficients such as 2,4-D, 2,6-D and 2,4,5-T are adsorbed onto vesicles, from solutions containing equimolar equilibrium concentrations of the unionised molecules, to markedly different extents (depending on the structure of the lipophilic portion of these molecules). Where the oil/water partition coefficient is higher, as for 2,4-dichlorophenol and 2-(2,4-dichlorophenoxy)ethanol, binding to vesicles may also arise due to non-specific solution within the hydrocarbon region of the lipid bilayers. The affinity of these compounds for lecithin has also been assessed by noting the extent to which the inclusion of lecithin in the oil phase increases the oil/water partition coefficient. This has shown that affinity for lecithin depends on the structure of both the lipophilic and hydrophilic portions of the molecule. Only the unionised form of the compounds examined had any large effect on ion flux across the vesicle membranes. Significant increases in the rate of chloride/nitrate exchange were obtained on introducing quite high concentrations (0.015 to 1.5 mM) of the compounds 2,4-D, 2,6-D, 2,4,5-T, IAA, and 2,4-dichlorophenol, but not 2,4-dichlorophenoxyethanol, to suspensions of lecithin vesicles. Similar flux increases were observed with lecithin/cholesterol vesicles except that more pronounced effects on flux were obtained on adding 2,4-dichlorophenol and 2,4-dichlorophenoxyethanol. In contrast 2,4-D, 2,6-D, 2,4-dichlorophenol and IAA had no significant effect on the rate of Na⁺/K⁺ ion exchange across lecithin vesicles although increases were observed with equimolar lecithin/cholesterol vesicles. Interpretations of these phenomena are suggested and their relevance to plant growth substance effects at the plasmalemma membrane discussed.