Recombinant canine distemper virus strain Snyder Hill expressing green or red fluorescent proteins causes meningoencephalitis in the ferret.

The propensity of canine distemper virus (CDV) to spread to the central nervous system is one of the primary features of distemper. Therefore, we developed a reverse genetics system based on the neurovirulent Snyder Hill (SH) strain of CDV (CDV(SH)) and show that this virus rapidly circumvents the blood-brain and blood-cerebrospinal fluid (CSF) barriers to spread into the subarachnoid space to induce dramatic viral meningoencephalitis. The use of recombinant CDV(SH) (rCDV(SH)) expressing enhanced green fluorescent protein (EGFP) or red fluorescent protein (dTomato) facilitated the sensitive pathological assessment of routes of virus spread in vivo. Infection of ferrets with these viruses led to the full spectrum of clinical signs typically associated with distemper in dogs during a rapid, fatal disease course of approximately 2 weeks. Comparison with the ferret-adapted CDV(5804P) and the prototypic wild-type CDV(R252) showed that hematogenous infection of the choroid plexus is not a significant route of virus spread into the CSF. Instead, viral spread into the subarachnoid space in rCDV(SH)-infected animals was triggered by infection of vascular endothelial cells and the hematogenous spread of virus-infected leukocytes from meningeal blood vessels into the subarachnoid space. This resulted in widespread infection of cells of the pia and arachnoid mater of the leptomeninges over large areas of the cerebral hemispheres. The ability to sensitively assess the in vivo spread of a neurovirulent strain of CDV provides a novel model system to study the mechanisms of virus spread into the CSF and the pathogenesis of acute viral meningitis.

Development of a challenge-protective vaccine concept by modification of the viral RNA-dependent RNA polymerase of canine distemper virus.

We demonstrate that insertion of the open reading frame of enhanced green fluorescent protein (EGFP) into the coding sequence for the second hinge region of the viral L (large) protein (RNA-dependent RNA polymerase) attenuates a wild-type canine distemper virus. Moreover, we show that single intranasal immunization with this recombinant virus provides significant protection against challenge with the virulent parental virus. Protection against wild-type challenge was gained either after recovery of cellular immunity postimmunization or after development of neutralizing antibodies. Insertion of EGFP seems to result in overattenuation of the virus, while our previous experiments demonstrated that the insertion of an epitope tag into a similar position did not affect L protein function. Thus, a desirable level of attenuation could be reached by manipulating the length of the insert (in the second hinge region of the L protein), providing additional tools for optimization of controlled attenuation. This strategy for controlled attenuation may be useful for a "quick response" in vaccine development against well-known and "new" viral infections and could be combined efficiently with other strategies of vaccine development and delivery systems.

Relative biological effectiveness of proton medical beam at Moscow synchrotron determined by the Chinese hamster cells assay.

PURPOSE: Assessment of relative biological effectiveness (RBE) of the proton medical beam at Moscow synchrotron. METHODS AND MATERIALS: The study was performed at Moscow proton medical facility (Institute for Theoretical and Experimental Physics). Relative biological effectiveness of the synchrotron proton beam was assessed at the entry of the unmodulated 179 MeV beam and in the center of spread out Bragg peak (SOBP), from measurements of the survival of Chinese hamster cells (clone 431). Gamma-radiation of 60Co was used as a reference source. RESULTS: According to the linear regression model, mean RBE values at 37% survival level were found to be 1.10 +/- 0.04 at the beam entry and 1.14 +/- 0.05 in the center of SOBP. Values of RBE obtained using the linear-quadratic model for 10% and 37% survival levels were 1.09 and 1.07, respectively, at the beam entry and 1.07 and 1.08, respectively, in the center of SOBP. CONCLUSIONS: The data obtained indicate that (a) the RBE values at the entry of the unmodulated beam and at the center of the SOBP are in close agreement, with an average of about 1.10; (b) protons are radiobiologically somewhat more effective than 60Co gamma rays; and, (c) high pulse dose rate of the medical beam does not significantly affect biological effects of the beam.

Neutron capture therapy with gadopentetate dimeglumine: experiments on tumor-bearing rats.

RATIONALE AND OBJECTIVES: The therapeutic effect of neutron capture therapy with the gadolinium (Gd) complex gadopentetate dimeglumine was studied in vivo in rats using a beam of thermal neutrons. METHODS: Rats with Jensen sarcomas 10-15 mm in diameter in their right thigh were irradiated with a thermal neutron beam that had fluences of 3.6 x 10(11) (20 min) or 5.4 x 10(11) n/cm2 (30 min) in the absence and presence of 5,500 or 13,750 ppm gadopentetate dimeglumine. Gadopentetate dimeglumine was administered directly into the tumor prior to neutron irradiation. Four groups of rats were studied: two groups of nonirradiated controls (Gd-n- and Gd+n-) and two irradiated groups (Gd-n+ and Gd+n+). In the follow-up period, we measured the subjects' clinical status and tumor size as a function of time postirradiation. RESULTS: In both control groups (Gd-n- and Gd+n-), the tumor progressively grew. Pure irradiation by thermal neutrons in the Gd-n+ group resulted in a transient inhibition of tumor growth with total regressions of 15%. Intratumoral administration of 13,750 ppm gadolinium per gram of tumor and subsequent neutron irradiation (the Gd+n+ group; fluence = 3.6.10(11) n/cm2) significantly increased the tumoricidal effects (i.e., decrease of tumor growth up to a complete regression of the tumors in about 80%). Treatment-specific differences between the groups were confirmed by histologic observations. CONCLUSION: The intratumoral administration of the hydrophilic magnetic resonance imaging contrast medium gadopentetate dimeglumine prior to irradiation with thermal neutrons leads to a therapeutic gain (i.e., reduction) on experimental Jensen sarcomas.

[Outbreaks of pseudotuberculosis and intestinal yersiniosis among Soviet specialists and members of their families in the Mongolian People's Republic]. / Vspyshki psevdotuberkuleza i kishechnogo iersinioza sredi sovetskikh spetsialistov i chlenov ikh semei v Mongol'skoi Narodnoi Respublike.

In summer and winter of 1986 two outbreaks of alimentary enteric diseases occurred among Soviet specialists and members of their families in Ulan Bator. These diseases were identified as Yersinia infections registered in Mongolia for the first time. In July 114 children in a kindergarten fell ill after being fed with salad prepared from vegetables and spring onions supplied from a nearby state farm. 20 Y. pseudotuberculosis cultures, serovar 1, were isolated, and in 25 persons antibodies to the isolated microorganisms were detected; altogether 32% of cases were confirmed by laboratory methods. During the December outbreak 187 persons were affected, among them 90% of children, through the consumption of imported oranges and tangerines, simultaneous infection with Y. enterocolitica, serovars 05.27 and 09, and hepatitis A virus being observed. The fact of associated infection was registered after the simultaneous detection of the markers of viral hepatitis A and Yersinia infection in 61 patients. In the kindergarten the disease produced a typical clinical picture of Far Eastern scarlatiniform fever, and in winter the abdominal forms of the disease prevailed. In cases of combined Yersinia and viral infection a specific variant of acute hepatitis developed; as regards this variant, the authors present heretofore unknown information on its epidemiology, clinical features and outcome.

[Total bioelectrical activity of the sensorimotor and visual cortices in rabbits during early neurological disorders from gamma irradiation at high doses]. / Summarnaia bioélektricheskaia aktivnost' sensomotornoi i zritel'noi kory golovnogo mozga krolikov v period rannikh nevrologicheskikh narushenii pri gamma-obluchenii v bol'shikh dozakh.

The overall bioelectrical activity of the sensorimotor and visual brain cortex of rabbits was estimated during early neurological impairment caused by 120 Gy gamma-irradiation. The characteristic changes were revealed in the amplitude, form, energy spectrum and spatial biopotential synchronization. The changes in the bioelectrical activity of the brain were associated with the clinically displayed stages of the neurological process development.

Shape Factor and Hydraulic Conductance in Noncircular Capillaries.

We use the Mason-Morrow shape factor, i.e., a dimensionless hydraulic radius, and corner half-angles to capture the geometry of noncircular capillaries pertinent to a physically adequate pore network description of porous media. We give analytic expressions for random corner half-angles that satisfy a given shape factor calculated from the microscopic images of pore space. We demonstrate that use of the shape factor leads to particularly simple expressions for the hydraulic conductance in single-phase flow through noncircular capillaries. In particular, we obtain the hydraulic conductances of arbitrary triangular ducts semianalytically, using conformal mapping. The conductances of equilateral triangular, rectangular, and elliptic ducts are calculated analytically. Copyright 2001 Academic Press.

Overcoming immune tolerance during oral vaccination against Actinobacillus pleuropneumoniae.

In the preliminary study mice were vaccinated orally with Actinobacillus pleuropneumoniae microsphere oral vaccine. The lung and eye mucous membranes of these mice did not contain increased immunoglobulin A (IgA) following the initial oral vaccination, possibly through antibody persistence and the phenomenon of immune exclusion. A similar tendency was found for serum IgG. However, after the second vaccination, IgA still did not increase significantly, which could be attributed to immune suppression due to the possibility of the intestine inducing immune tolerance. Only the third vaccination overcame this effect and increased the level of IgA. In order to achieve a high systemic and local immune response this study attempted to overcome the initial tolerance to oral vaccination by using temporary immunosuppression, increasing antigen dose, and prolonging vaccine influence. Triamcinolone, used in the later productive phase of the immune response after the first and second vaccinations, but restricted in the inductive phase of the second and third vaccinations, could disable immune tolerance. Suppression of antibody production before the next induction of the immune response by an oral vaccine combined with suppression of cell-suppressor activity led to the creation of systemic immunity with the possibility of high levels of A. pleuropneumoniae growth inhibition. Increased antigen doses or durable consumption of antigen could overcome immune exclusion of antigen by primary antibodies. Even very low doses of vaccine (4.5 mg) could induce a primary immune response, and a dose increased by 10-fold for the second vaccination could overcome tolerance and maintain high systemic immunity. Chronic consumption of oral vaccine led to benefits in the quantity of local (not systemic) antibodies. The outcomes of the study can be adapted for practical oral immunization of pigs.

[Correlation between the complex of body reactions to exposure to acute hypoxia and individual radiosensitivity in irradiation at a dose of 200 Gr]. / Sootnoshenie mezhdu kompleksom reaktsii organizma na vozdeistvie ostroi gipoksii i individual'noi radiochuvstvitel'nost'iu pri obluchenii v doze 200 Gr.

A study was made of a correlation between the response of basal metabolism to acute hypoxia and the life span of rats after irradiation resulting in the development of a cerebral form of radiation sickness. The more radiosensitive animals consumed a larger amount of oxygen, exhaled a lesser amount of carbon dioxide, and showed an increased normal expiratory exchange per minute. After the effect of acute hypoxia all the indices under study exhibited an opposite picture.

[The electrical activity of the monkey brain in the period of early transient incapacity during gamma-irradiation at high dose rates]. / Elektricheskaia aktivnost' golovnogo mozga obez'ian v period rannei predkhodiashchei nedeesposobnosti pri gamma-obluchenii s vysokoi moshchnost'iu dozy.

Changes in the electroencephalogram (EEG) of Macaca fascicularis during early transient incapacitation (ETI) were shown to correlate with the dynamics of clinical manifestations of the damage. Irradiation caused desynchronization of EEG followed by a generalized retardation of its fluctuations reaching the maximum at the height of ETI. EEG disturbances in animals during the comatose phase of ETI indicated a severe inhibition of the brain cortex functional activity.

[Early transient incapacitation of monkeys exposed to high-energy electrons and gamma-irradiation in supralethal doses]. / Ranniaia prekhodiashchaia nedeesposobnost' u obez'ian pri vozdeistvii élektronov vysokikh énergii i gamma-izlucheniia v supraletal'nykh dozakh.

Irradiation of Macaca fascicularis with electrons (24 MeV, 46 and 104 Gy) and gamma-quanta (60Co, 77 and 138 Gy) caused early transient incapacitation (ETI) and severe symptoms of neurological disturbances. Two types of the ETI clinical patterns were distinguished: a dyskinetic type marked by ataxia; and a severer, comatose type manifested by disappearance of voluntary movements, areactivity, and temporary loss of reflexes.