Effect of a viral infection on the cellular chromosome apparatus of mice in vitro and in vivo against a background of hydrocortisone action]

A cytogenetic investigation of murine bone marrow after hydrocortison injection has been made. High doses of hormone (50 mg/kg) provoke deteriorations in bone marrow both in the structure and in the chromosome number. A dose of 5 mg/kg has no such effect. The Koksak A13 virus does not induce cytogenetic deteriorations in mice, however, it is able to produce a big mutagenic effect on the hydrocortison background. The vaccine strain of measles virus -- Leningrad-16 -- also increases its mutagenic action on the bone marrow cell chromsome apparatus of mice affected with hydrocortison. At the same time, in the cell culture of murine kidney, hydrocortison does not induce chromosome deteriorations and even lowers the frequency of cells with deteriorations in the chromosome set during the initial days after injecting the virus culture with measles virus.     

The effect of cyclosporin A on the islet cells of mice]

The action of immunosuppressive agent ciclosporin A on the insular apparatus was studied with an original method of cytochemical zinc detection in experiments on mice. The drug was found to lower zinc levels in pancreatic beta-cells. In ciclosporin A pretreatment the sensitivity of mice to zinc-binding diabetogenic agent enhanced.     

The effect of an artificial magnetic field on Salmonella infection in mice]

Experimental Salmonella infection in mice, developing simultaneously with the prolonged action of an artificial constant magnetic field with induction equal to 3 x 10(-4) T, was found to induce a pronounced decrease in nonspecific resistance in the animals. The study of Salmonella population structure revealed that the cells selected the animals subjected to the action of the artificial magnetic field had mostly a lesser number of signs of antibiotic resistance. By the end of the experiment Salmonella cultures isolated from the mice subjected to the action of the artificial magnetic field were characterized by greater virulence and resistance to the bactericidal action of blood serum. The use of sodium nucleinate under the conditions of the action of the artificial magnetic field enhanced the level of anti-infectious protection in the animals, which changed the direction of cell selection in Salmonella population towards cells with a greater number of markers of antibiotic resistance.     

Enumeration of single IFN-gamma-producing cells in mice during viral and bacterial infection

A solid phase immunoenzymatic technique was employed for detecting single IFN-gamma-producing cells (IFN-gamma PC) in the mouse. After infection with lymphocytic choriomeningitis virus or Listeria monocytogenes, the numbers of IFN-gamma PC in spleens began to rise on day 4, attained maxima on days 7 and 8, and declined thereafter. Negative selection in vitro by use of mAb and C allowed phenotypic identification of the producer cells; most, if not all, carried Thy-1, and approximately one half expressed CD4, the other half, CD8. Depletion of cells in vivo by treatment of mice with mAb led to somewhat different results; again, anti-Thy-1 antibody eliminated essentially all IFN-gamma PC, but considerably more than 50% were either CD4+ or CD8+, suggesting regulatory interactions between these T lymphocyte subsets with regard to generation of the lymphokine.     

Intrathymic effect of acute pathogenic SHIV infection on T-lineage cells in newborn macaques

We intrarectally infected newborn macaques with a pathogenic simian/human immunodeficiency virus (SHIV) that induced rapid and profound CD4 (+) T cell depletion, and examined the early effects of this SHIV on the thymus. After intrarectal infection, viral loads were much higher in the thymus than in other lymphoid tissues in newborns. In contrast, no clear difference was seen in the viral loads of different tissues in adults. Histological and immunohistochemical observations showed severe thymic involution. Depletion of CD4 (+) thymocytes began in the medulla at 2 weeks post infection and spread over the whole thymus. After in vivo infection, the CD2 (+) subpopulation, which represents a relatively later stage of T cell progenitors, was selectively reduced and development of thymocytes from CD3 (-) CD4 (-) CD8 (-) cells to CD4 (+) CD8 (+) cells was impaired. These results suggest that profound and irreversible loss of CD4 (+) cells that are observed in the peripheral blood of SHIV-infected monkeys are due to destruction of the thymus and impaired thymopoiesis as a result of SHIV infection in the thymus.     

Protective effect of caffeine on chromosomal structures of mammalian cells irradiated with UV-rays]

The effect of caffeine (2mM) on the frequency of structural mutations induced by UV light (lambda = 265 nm at an incident dose of 40 erg/mm2) in the primary culture of mouse embryonic fibroblasts is studied. A half-hour treatment with caffeine of cells at the time of the first mitosis metaphase decreased approximately by 2 times the frequency of chromosome aberrations induced by UV light at the S stage and observed at the metaphase of this or the next C-mitosis. The frequency of both breaks and exchanges decreased as the result of caffeine treatment. The persistence of the protective effect of caffeine at the time of the second C-mitosis suggests that the observed decrease of the aberration rate is accompanied by the true reparation of pre-mutational lesions in chromosomes; the nature of the reparative process and the time when it takes place is as yet not clear. Caffeine did not decrease the frequency of spontaneous structural mutations.     

The effect of air ions on bacterial and viral pneumonia in mice

Ambient air untreated for removal of ordinary pollutants and ionized with tritium powered generators to contain 1–2 × 10⁵ small positive ions/cm³ accelerated the rate of death of mice challenged intranasally with measured doses of KLEBSIELLA PNEUMONIAE or of the PR8 strain of influenza virus. The differences between the cumulative mortality rates of controls and ion-treated animals were significant (p < 0.05 to p < 0.001) for several days of the period of observation. Exposure of infected mice to an electrical field of the same strength as that used for ion-treated mice showed no statistically significant field effect. Repetition of the influenza virus experiments using pollutant-free air and ion densities averaging 4.1 × 10⁵ small positive ions/cm³ produced essentially the same results. The observation that high concentrations of positive ions accelerate the rate of death in pulmonary infections with KLEBSIELLA PNEUMONIAE and with influenza virus conforms to the pattern of earlier work with COCCIDIOIDES IMMITIS.

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Zusammenfassung Ungereinigte Umgebungsluft mit 1–2 × 10⁵ kleinen positiven Ionen/cm³ nach Ionisation mit Tritiumbetriebenen Generatoren beschleunigte die Todesrate von Mäusen, die intranasal mit bekannten Mengen KLEBSIELLA PNEUMONIAE und PR8 Influenza Virus okuliert worden waren. Die Unterschiede zwischen den Kontrolltieren und den ionenbehandelten Tieren waren an mehreren Beobachtungstagen signifikant (p < 0,05 bis p < 0,001). Die Exponierung der infizierten Tiere in einem elektrischen Feld der gleichen Stärke, wie für die ionenbehandelten Tiere verwendet wurde, ergab keine statistischen Unterschiede. Die Wiederholung der Versuche mit Influenza Virus in reiner Luft mit 4,1 × 10⁵ kleinen positiven Ionen/cm³ ergab die gleichen Ergebnisse.

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Resume De l'air non purifié additionné de 1–2 × 10⁵ petits ions positifs/cm³ — ions provenant de générateurs au Trititium — a augmenté le taux de décès de souris qu'on avait au préalable infectées par le nez de quantités déterminées de KLEBSIELLA PNEUMONIAE et de virus d'influenza PR8. La différence du taux cumulatif de mortalité entre des animaux traités avec cet air ionisé et des témoins a été significative pour chacun des jours de la période d'essais (p < 0,05 à p < 0,001). L'exposition de souris infectées à un champ électrique de même intensité que celui utilisé pour les animaux traités n'a pas présenté d'effets significatifs. La répétition de l'essai avec le virus de l'influenza, mais en utilisant de l'air libre de tout polluant et une densité d'ions moyenne de 4,1 × 10⁵ petits ions positifs/cm³ a conduit à des résultats similaires. La constatation que de hautes concentrations en ions positifs augmente le taux de décès dûs à des infections pulmonaires avec KLEBSIELLA PNEUMONIAE et avec le virus de l'influenza vient confirmer le résultat d'un essai antérieur pratiqué avec COCCIDIOIDES IMMITIS.

     

Effects of viral infection on contraction of the diaphragm in mice

Isometric contractile properties of isolated phrenic nerve-diaphragm muscle preparations were used to study the effects of picornavirus infections on diaphragm muscle function. Properties of muscles from virus-inoculated and control mice were similar during brief contractions. However, when subjected to a series of fatiguing contractions by indirect or direct stimulation, muscles of mice inoculated with a paralytic variant of encephalomyocarditis (EMC) virus showed a greater rate of fatigue and a reduced capacity to recover from fatigue than did muscles from uninoculated control mice or muscles from mice inoculated with a nonparalytic coxsackievirus B3 (CVB3). Mice paralyzed by EMC virus infection had high titers of virus in the brain and similar titers of virus in diaphragm muscle as found in diaphragm muscles of CVB3-inoculated mice. The results indicate that EMC virus infection of mice leads to increased fatigability of the diaphragm muscle and that there are both neural and muscular components of this enhanced fatigue.