Tolerance breaking by lymphocyte activating factor induced by Escherichia coli O138 lipopolysaccharide from homologous macrophages.

Following an antigenic dose of 10 microgram or a tolerogenic dose of 200 microgram of Escherichia coli O138 lipopolysaccharide (LPS), BALB/c mice were examined on day 14 for percentages of theta-bearing cells. A considerable increase in T cells was noticed in lymphocytes from tolerant draining lymph nodes, and furthermore these cells did not possess receptors for LPS when tested for rosette inhibition. However, when the supernatant from 1 X 10(7) macrophages, pretreated with 150 microgram LPS, was given to tolerant mice on day 7, by day 14 tolerance was found to be broken, anti-LPS IgG was present in circulation and the draining lymph node contained T cells specifically committed to LPS. The change from suppressor to helper T cell activity is discussed in relation to enhancement of the immune response.     

Arbovirus isolations from mosquitoes in South Slovakia.

In the years 1973 and 1975 mosquitoes and some other Diptera (Tabanidae, Simuliidae, Hippoboscidae) were tested for virus. 13,924 mosquitoes, 75 horseflies and 60 blackflies were processed in 1973. Five strains of Tahyna virus were isolated from mosquito species Aedes vexans. 3,378 mosquitoes and 12 sheep keds were tested for virus in 1975. Twelve strains of Calovo virus were isolated from Anopheles maculipennis and one strain of Tahyna virus was obtained from Aedes vexans mosquitoes.     

Nerine latent virus: some properties and serological detectability in Nerine bowdenii

Nerine latent virus (NeLV), first found inNerine bowdenii, may occur also in the otherNerine species investigated so far:N. sarniensis, N. flexuosa Alba, andN. Mansellii. Chenopodium amaranticolor, C. quinoa, andGomphrena globosa sometimes reacted with local lesions after mechanical inoculation with NeLV.Nicotiana clevelandii andHippeastrum were symptomless hosts. In this respect NeLV resembled the incompletely describedHippeastrum latent virus (HLV).Serologically NeLV was closely related to HLV and to carnation latent virus (CaLV), but differed from the latter in host plant reaction. A more distant relationship was observed with some other carlaviruses, wheareas NeLV also reacted with an antiserum to potato virus X.Depending on the lot, NeLV could be detected rather reliably with the micro-precipitin test inN. bowdenii Van Roon, but less well in 63. Better results were obtained with the microplate method of enzyme-linked immunosorbent assay (ELISA).The average particle length was 664 nm, the sedimentation coefficient 155 S and the buoyant density 1.298 g/cm³.NeLV can be considered as a member of the carlavirus group. On basis of priority HLV may be considered as NeLV.     

Inhibition of chitin synthesis by two 1-(2,6-disubstituted benzoyl)-3-phenylurea insecticides. II

The knowledge of the biochemical mode of action of 1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl)urea (diflubenzuron) is presented, explaining the insecticidal effect. Like its structural analog, 1-(2,6-dichlorobenzyl)-3-(3,4-dichlorophenyl)urea (Du 19111), it inhibits chitin synthesis in the cuticle of larvae. Virtually complete inhibition was demonstrable 15 min after the application of diflubenzuron. Neither diflubenzuron nor Du 19111 has any effect upon chitinase activity either in vivo or in vitro. The insecticidal effect upon the cuticle, therefore, must be explained as an inhibition of chitin synthesis and not as an activation of chitin degradation. In contrast to the action of Du 19111, no accumulation of N-acetylglucosamine occurs upon treatment of larvae with diflubenzuron. Similarities and differences in the mode of action of both compounds are discussed, together with other effects reported in the literature.     

Etiology of the stomatitis pneumoenteritis complex in Nigerian dwarf goats.

The causative agent of stomatitis pneumoenteritis complex was isolated in domesticated goats and Vero cell culture. It was identified immunologically and morphologically as identical with the "Peste des Petits Ruminants" virus. There were cross reactions between stomatitis pneumoenteritis complex virus isolate and rinderpest virus by immunodiffusion and complement fixation tests but no cross neutralization. Goats recovered from stomatitis pneumoenteritis complex were protected against a challenge with rinderpest virus that was lethal to control goats. Ultrastructural morphology revealed intracytoplasmic and intranuclear inclusions made up of random arrays of fibrillar strands. Pleomorphic particles budded from the plasma membrane of infected cells and enveloped virions were seen extracellularly. Specific ferritin tagging was demonstrated in the stomatitis pneumoenteritis complex virus infected cells treated with homologous and peste des petits ruminants viral antibody systems but little, if any, tagging in the heterologous rinderpest system.     

Phagocytic acitivity of bovine leukocytes during pregnancy.

The phagocytic competence, measured as the total number of polymorphonuclear leukocytes per mm3 which phagocytosed Staphylococcus aureus, strain 321, in vitro, was determined in eight cows during complete pregnancies. Such leukocytes are referred to as "Active PMN'S". There was a gradual decline in the number of these cells from conception to a minimum between the 16th and 20th weeks of pregnancy, followed by a steady increase to the cessation of lactation when a marked drop occurred, after which there was an increase to a maximun during the second week prepartum. From this maximum there was a rapid decrease to an absolute minimum during the first week after parturition. From the second week postpartum there was a gradual increase to conception. The correlation coefficient (r) of number of active PMN'S with time before conception was -0.474 )p-0.01). There were significant differences (p=0.01) in numbers of active PMNS Among the eight cows. It was found that the cows fell into two groups, one whose members had, overall, significantly more active PMNs (p=0.001) than those in the second group. The between cow differences may have been due to 1) age, since the cows with the highest numbers of circulating active PMNs were younger than those in the other group of 2) the combined stress of pregnancy and lactation, as those cows which were both pregnant and milking had the lowest numbers of active PMNs.     

Endocrine and sperminogenic testicular function. 8. Relationships between testicular and plasma testosterone concentrations as well as between the number of Leydig cells in testicular tissue and their cell nucleus volume in boars of different ages]

Testicular tissue and blood samples (V. spermatica interna) were taken from 32 boars during castration. The animals were different age groups. Against this background, studies were conducted into the correlations between testicular and plasma testosterone, on the one hand, and the amount of interstitial cells of Leydig in testicular tissue as well as the latters' cell nuclei volumes, on the other. The results seemed to support the conclusion that any age-dependent increase of testicular and plasma testosterone concentrations was caused unambigously by an absolute increase in volume of androgenic testicular tissue, in concomitance with testicular growth, in other words, by rise in the total number of interstitial cells of Leydig.     

Structure-activity relationships of 1,2,3-benzothiadiazoles as synergists for carbaryl against the house fly (Musca domestica)

Fifty six 1,2,3-benzothiadiazoles and related compounds were evaluated as carbaryl synergists against the house fly (Musca domestica). Many of these were excellent synergists, the most active being those containing various combinations of halogen, alkyl, or alkoxy substituents in the 5- and/or 6-positions of the ring.Regression analysis on the data from 14 compounds for which substituents constants were available established that synergistic activity can be satisfactorily described by equations in terms of the hydrophobic bonding constant (π) and the homolytic free radical constant (σ ·).The results with compounds related to the 1,2,3-benzothiadiazoles suggest that synergistic activity is associated primarily with the diazosulfide moiety.     

First record of bacillary rickettsia-like organisms in European tick Dermacentor marginatus (Sulzer).

Bacillary rickettsia-like organisms (BRLO) were found in the tick Dermacentor marginatus. They are gram-negative and differ from common bacteria and reckettsiae both in the cultivation conditions and morphology. BRLO are non-pathogenic for ticks and guinea pigs. In our studies they were isolated on half-engorged females of D. marginatus, on which they are still maintained.     

Cestodes of ruminants in Afghanistan.

Five cestode species parasitizing ruminants were found for the first time in Afghanistan: Moniezia benedeni, M. expansa, Avitellina centripunctata, Stilesia globipunctata, and Thysaniezia giardi.