Studies on the pathogenicity of Acholeplasma axanthum in swine

Acholeplasma axanthum sp. was isolated from the lung of swine with catarrhal pneumonia. Clinical symptoms of respiratory disease, gross and histological lesions of pneumonia, as well as serological response were produced by intranasal inoculation of ;miniature pigs' with the supernatant of lung suspension containing Acholeplasma axanthum and by a 48 hr. broth culture of the strain.A similar picture of disease was observed in animals held in contact with the animals inoculated with untreated lung suspension. Acholeplasma axanthum was isolated from the nasal cavity, lung and peribronchial lymph nodes 7-41 days after inoculation. No lesions were observed after inoculation of pigs with the supernatant of lung suspension pretreated with oxytetracycline or chloroform, and no successful isolation of Acholeplasma axanthum could be achieved after this treatment.

The regulation of the limb circulation in lymph-oedema (development of an arteriovenous shunt circulation in experimental lymph-oedema of the leg)

The effect of lymph stasis on limb blood flow was studied in 38 dogs where lymph-oedema of one of the hindlimbs was induced by ligation of the lymphatics on the thigh and of the regional lymph-node. Haemodynamic examinations were conducted in 17 animals; total blood flow and the nutritive flow to the muscles and skin (⁸⁶Rb extraction) were determined in both hindlimbs. Microcirculation was studied in 16 dogs by means of the india ink-gelatin injection method, the benzidine reaction and by the polyvinylchloride injection technique. In all cases specimens were taken from muscle, skin and subcutaneous connective tissue of both hindlimbs for light microscopic analysis. The results presented indicate an increase in total blood flow without any change in the nutritive flow to the skin or muscle in the lymph-oedematous limb. Lymph stasis induced intimal swelling and plasma infiltration of the intima and media of small vessels (pre-capillaries and metarterioles) of skin, muscles and subcutaneous tissue, which led to a blocked transportation of proteins. Small vessels of the limb with lymph-oedema were spottily dilated, whereas at other areas compressed capillaries could be seen. Evidence is supplied for the appearance of arteriovenous shunt circulation in lymph-oedema of the lower limb. In a previous study we observed that, unlike venous congestion, lymph-oedema of the limbs in man was accompanied by increased blood flow and a conspicuously low arteriovenous oxygen difference in the limb. (1) This finding led us to assume that chronic lymph stasis may induce arteriovenous shunt circulation. The present experiments were designed to study relative changes of total and nutritive limb blood flow and to examine alterations of the microcirculation in experimental lymph-oedema of the limb.

The role and significance of vasodilatation in the development of small arterial lesions in the rat

Repeated treatment with large doses of vasodilators elicited small arterial changes in rats. Similar lesions developed on alternate dosage of vasodilator and vasoconstrictor preparations. The mechanical strain imposed on the vessel wall by both types of vasoactive substances is believed to play a role in the pathomechanism of the vascular changes which seem essentially to arise from the impairment of the smooth muscle cells overburdened by forced movements of the vessel wall.

Investigations of the permeability changes of the vascular wall in experimental malignant hypertension by means of a colloidal iron preparation

Changes in the permeability of small arteries in experimental malignant hypertension were investigated by means of colloidal tracers. Simultaneously with the development of hypertensive lesions of the vascular wall, an infiltration of plasma was observed. It was possible to facilitate the recognition of this infiltration by the injection of colloidal iron and of colloidal carbon particles; the particulate material escaped from the plasma and accumulated locally within the vessel wall.

The iron preparation appears to be better suited than carbon for the study of the initial stage of enhanced vascular permeability since iron can be easily detected with both the light and the electron microscope and is bound to a definite serum protein fraction. Furthermore, the presence of iron is recognisable earlier than that of carbon.

Possible explanation for the metabolic radioprotective effect of cysteine on Escherichia coli B

The growth of logarithmic-phase cultures of E. coli B cells on glucose-mineral medium was partially inhibited by 0.2 mM L-cysteine-HCl. Twenty other amino acids failed to show a similar inhibiting effect even at a concentration of 10 mM. After incubation of the log-phase culture in the presence of 2.0 mM cysteine for 30 minutes (inhibition about 70 %) the cells were centrifuged, resuspended, and diluted 200-fold in cysteine-free phosphate buffer. These cells exhibited increased resistance to the effect of X-rays as measured by the number of colony-forming units (DRF = 2.1). Both the growth-inhibiting and the radioprotective effects of cysteine could be diminished by the presence of 0.5 mg of casein hydrolyzate per milliliter during the 30-minute preirradiation culture period. This "anti-cysteine" effect was caused mainly by L-leucine, L-isoleucine, L-valine, and L-threonine from among the amino acids of casein hydrolyzate. It is suggested that cysteine inhibits the biosynthesis of some amino acids, thereby blocking protein synthesis, which may result in increased radioresistance.