Tumor incidence in Visna virus inoculated mice.

Mice (female Swiss albino) inoculated when newborn with Visna virus had tumors in 77% of cases when examined 8-12 months later. The tumors were mainly of the mammary carcinoma type. The tumor incidence in non-infected control animals was only 20%. In contrast, no increased incidence of tumors was observed among Visna virus-inoculated inbred mice (BALB/c, CBA and DBA) with low incidence of spontaneous mammary carcinoma.     

Tumor incidence in Visna virus inoculated mice

Summary Mice (female Swiss albino) inoculated when newborn with Visna virus had tumors in 77% of cases when examined 8–12 months later. The tumors were mainly of the mammary carcinoma type. The tumor incidence in noninfected control animals was only 20%. In contrast, no increased incidence of tumors was observed among Visna virus-inoculated inbred mice (BALB/c, CBA and DBA) with low incidence of spontaneous mammary carcinoma.This study was supported by grant No. B75-16X-4511-01 of the Swedish Medical Research Council.     

Chromosome aberrations in cattle raised on bracken fern pasture

Thirteen cows maintained on natural bracken fern (Pteridium aquilinum) were analyzed cytogenetically. The frequency of structural chromosome aberrations detected in peripheral blood cells was significantly higher when compared to that detected in animals raised on pasture containing no bracken fern. We discuss the clastogenic action of fern and its synergistic action with infection by type 2 and 4 papilloma virus in the same animals.     

Failure of SV40-transformed lizard cells to induce tumors in autogeneic or allogeneic hosts

Summary Lizard cells from the tails of geckos were readily morphologically and antigenically transformed in vitro by SV40 virus. Neither autografts of these cells nor allografts of SV40 transformed gecko embryo cells produced tumors in animals under observation from 1 to 3 years.     

Failure to SV40-transformed lizard cells to induce tumors in autogeneic or allogeneic hosts.

Lizard cells from the tails of geckos were readily morphologically and antigenically transformed in vitro by SV40 virus. Neither autografts of these cells nor allografts of SV40 transformed gecko embryo cells produced tumors in animals under observation for 1 to 3 years.     

Modifications by Nematoda of the sensitivity of mice to Salmonella abortus ovis administered orally or subcutaneously]

Mice inoculated 6 to 9 days previously with Heligmosomoides polygyrus (=Nematospiroides dubius) become more frequently infected than controls after an oral challenge with a constant dose of Salmonella abortus ovis. But parasitism increases the LD 50 when the subcutaneous route of infection is used, probably by stimulating the immune system of the host.     

Effect of vitamin A on tumor development in burned, unburned, and glucocorticoid-treated mice inoculated with an oncogenic virus.

High doses of vitamin A decreased the severity of tumor development in mice inoculated with a murine sarcoma virus; the same doses of vitamin A had no effect on the increased tumorigenesis seen in animals severely stressed with thermal injury or the increased tumorigenesis induced by exogenous glucocorticoid administration.     

Immunologic blood-brain barrier in the polyoma virus--Syrian hamster system]

The authors report premilinary results of an experiment on permeability of the blood-brain barrier (BBB) to anti-tumor virus-induced immunological factors in the polyoma virus/Syrian Hamster system. The animals were protected by subcutaneous or intracranial injections with virus before challenge with polyoma virus transformed cells by both routes. BBB seemed to be permeable to the efferent part of the subcutaneously induced immune reaction. On the contrary, antigenic information introduced in the central nervous system was trapped inside the BBB. Thus the BBB might offer a "one-way" permeability in this system.     

Tumor induction in mice treated with hydrocortisone and innoculated with polyoma transformed hamster cells]

Tumors have been induced in hydrocortisone treated Mice innoculated with wild-type polyoma transformed Hamster cells. The filtrate from these tumors infects Mouse embryo cells and induces the production of polyoma virus. The polyoma virus has been characterised in the infected cells with anti-polyoma capsid serum.     

Chromsome aberrations in cattle raised on bracken fern pasture

Summary Thirteen cows maintained on natural bracken fern (Pteridium aquilinum) were analyzed cytogenetically. The frequency of structural chromosome aberrations detected in peripheral blood cells was significantly higher when compared to that detected in animals raised on pasture containing no bracken fern. We discuss the clastogenic action of fern and its synergistic action with infection by type 2 and 4 papilloma virus in the same animals.Acknowledgments. We are grateful to Dr F. J. Benesi, Dr J. L. Guerra and Dr I. L. Sinhorini for performing some of the clinical and pathological analyses; O. P. Ferraz, L. A. Tadeu Dias, L. F. Feitosa and A. M. N. Paiva for technical assistance; and to Dr N. H. C. Castro and Dr C. de Araujo Peres for critical and statistics review, respectively. Research was supported by CNPq FAPESP and CAPES.     

Effect on non-steroidal anti-inflammatory drugs on Moloney sarcoma virus inoculated mice

Summary Chronic administration of phenylbutazone, flufenamic acid and a new, potent non-steroidal anti-inflammatory agent ITF (3-methyl-5-benzoyl-amino-isothiazole-4-carboxy-p-ethoxyphenylamine) to BALB/c mice inoculated with a Moloney sarcoma virus resulted in a stimulation of tumor growth and increased severity of disease. This treatment, however, had no effect on the spontaneous regression of tumors. Indomethacin in a dose of 5.0 or 2.5 mg per kg suppressed the MSV-induced tumor growth, but this effect was apparently connected with the high toxicity of this drug for mice.     

The influence of cold or isolation stress on resistance of mice to West Nile virus encephalitis

The effect of cold or isolation stress on mortality rate and brain virus level were investigated in mice infected with West Nile virus (WNV). Exposure of mice for 5 min/day to cold water (1 +/- 0.5 degrees C) for 8-10 days resulted in 92% mortality as compared to 47% in control mice (p less than 0.001). Mice housed in individual cages (isolation stress) were also more susceptible to WN viral infection, as shown by increased mortality rate reaching 85% as compared to 50% in mice housed 6 per cage (p less than 0.01). Cold or isolation stress increased blood brain and spleen virus levels as early as 2 days after inoculation. After 8 days of isolation or cold stress, mice inoculated with WNV had 8.9 and 9.0 log10 plaque forming units in the brain, respectively, as compared to 6.9 in the control (p less than 0.01-0.001). Furthermore, lymphoid organs such as spleen and thymus showed severe mass loss. These data suggest that physical or non-physical stress situations enhance WNV encephalitis by accelerating virus proliferation and increase mortality in mice.     

Über die Entwicklung des Fremdkörpergranuloms in verschiedenen Organsystemen

Summary The weight has been measured of the granuloma produced after implantation of the same foreign body in the kidneys, the testes, the liver and the subcutaneous tissue of male rats. It was found that granulomae in the testes and liver are nearly twice as heavy as in the kidney or in the subcutaneous tissue. Enhancement or inhibition of this reaction by treating the animals with cortexone shows organ-dependent effects on granuloma formation.     

The influence of cold or isolation stress on resistance of mice to West Nile virus encephalitis

Summary The effect of cold or isolation stress on mortality rate and brain virus level were investigated in mice infected with West Nile virus (WNV). Exposure of mice for 5 min/day to cold water (1±0.5°C) for 8–10 days resulted in 92% mortality as compared to 47% in control mice (p<0.001). Mice housed in individual cages (isolation stress) were also more susceptible to WN viral infection, as shown by increased mortality rate reaching 85% as compared to 50% in mice housed 6 per cage (p<0.01). Cold or isolation stress increased blood brain and spleen virus levels as early as 2 days after inoculation. After 8 days of isolation or cold stress, mice inoculated with WNV had 8.9 and 9.0 log₁₀ plaque forming units in the brain, respectively, as compared to 6.9 in the control (p<0.01–0.001). Furthermore, lymphoid organs such as spleen and thymus showed severe mass loss. These data suggest that physical or non-physical stress situations enhance WNV encephalitis by accelerating virus proliferation and increase mortality in mice.     

Purification and study of equine infectious anemia virus antigens, produced in vivo or in cultured cells]

The G and C antigens of equine infectious anemia virus have been produced in vivo and in infected cell culture, then they have been purified. Their physico-chemical properties have been determined, particularly their molecular weight, their sedimentation coefficient, their density and the iso electric point.     

Paralysies révélatrices de la leucémie de Gross chez le rat

Summary Inoculation of Wistar CF rats with Gross virus induces in 86% of the animals a leukaemia which is associated, in nearly 50% of the cases, with a paralysis of the hind legs.This paralysis is due to the compression of the spinal cord by leukaemic cell infiltrates which develop in the lumbar area. No neurotropic virus has been found in these animals.     

Role of Friend-associated lymphatic leukemia virus in immunization against Friend leukemia complex

Summary Mice inoculated with Friend leukemia complex (FLC) pretreated with concanavalin A are resistant to FLC challenge only when they have become infected with the FLC-associated lymphatic leukemia virus (LLV). In interpreting states of resistance to FLC induced by various immunizing procedures, the possibility that immunity is sustained by an unrecognized LLV infection should always be considered.Supported by a grant from the Italian National Research Council.     

Pulmonary edema in mice infected with Plasmodium berghei. Involvement of catecholamines

Mice inoculated with Plasmodium berghei developed a drastic and significant pulmonary edema. Treatment of animals with phenoxybenzamine rendered mice hyporeactive to this physiopathological alteration.     

Ulteriori dati sull'attività dei derivati triazinici nelle infezioni da virus

Summary A number of 2-amino-4-morpholinyl-s-triazine derivatives has been synthetized by the authors, and the activity of these compounds has been tested against some viral infections in laboratory animals.Among these substances, the compounds having the NH₂ group free or monosubstituted, and the 6-CH group unsubstituted, revealed an interesting protective activity in Swiss albino mice infected with influenza virus type B.The compound 2-morpholinyl-4-acetylamino-s-triazine, able to protect the animals when administered by oral route and non-toxic, has been tried in viral diseases in human beings.     

The effect of actinomycin D on the production of viruses by the protoplasts of Chinese cabbage infected in vitro by the yellow mosaic virus of turnips]

Chinese Cabbage (Brassica sinensis L. var. Cantonner) protoplasts were infected by Turnip yellow mosaic virus (TYMV) and inoculated in the presence or absence of actinomycin D. Virus production was determined 40 hrs. after inoculation, the time required for the virus replication cycle to be terminated. While actinomycin D had no effect on TYMV production when present at a concentration of 1 microng/ml, a 50 to 80% inhibition of virus production was noticed at concentrations of the order of 5 to 10 microng/ml, and the inhibition reached 90% with 25 microng/ml.