Newborn Hamsters Research Articles

Evaluating the sensitivity of newborn rats and newborn hamsters to oncogenic DNA

To evaluate the risk of residual cellular DNA in vaccines manufactured in tumorigenic cell lines, we have been establishing in vivo assays to quantify the oncogenic activity of DNA. We had generated three oncogene-expression plasmids: pMSV-T24-H-ras, which expresses activated H-ras; pMSV-c-myc, which expresses c-myc; and pMSV-T24-H-ras/MSV-c-myc, which expresses both oncogenes. Tumors were induced in mice by pMSV-T24-H-ras plus pMSV-c-myc or by pMSV-T24-H-ras/MSV-c-myc. Because newborn hamsters and newborn rats have been recommended for oncogenicity testing of the DNA from tumorigenic mammalian cell-substrates used for vaccine production, we evaluated their sensitivity. Newborn hamsters and rats were inoculated with different doses of pMSV-T24-H-ras/MSV-c-myc to determine their sensitivity to tumor induction and with the single-oncogene-expression plasmids to determine whether single oncogenes could induce tumors. Newborn rats were more sensitive than newborn hamsters, and activated H-ras but not c-myc induced tumors in newborns of both rodent species. DNA from four cell lines established from tumors induced by pMSV-T24-H-ras/MSV-c-myc was inoculated into newborn rats. Because no tumors were induced by this cellular DNA, which should be optimal as it contains both oncogenes linked and present in several copies, we conclude that available in vivo models are not sensitive enough to detect the oncogenicity of cellular DNA.

Studies of biological properties of continuous suspension ВНК-21/SUSP/ARRIAH cell line

The results of the studies of cytomorphological, karyological, cultural properties of continuous suspension ВНК-21/SUSP/ARRIAH subline of newborn Syrian hamster kidney cells intended for foot-and-mouth disease, rabies, bovine parainfluenza-3, Aujeszky’s disease virus reproduction, as well as for production of diagnostic veterinary biologicals are presented. When cultured in suspension, BHK-21/SUSP/ARRIAH cell subline undergoes selection towards hypoploidy: modal class is represented by cells with 41 chromosomes (32–40% of cells); the share of cells containing 40–42 chromosomes is 78–80%; the share of polyploids averages around 1%; the range of variation in the number of chromosomes is from 36 to 54. BHK-21/SUSP/ARRIAH cell subline cultured in suspension with cell seeding concentration of 0.6–0.8 million cells/cm3 demonstrates growth rate of 6.67–11.00 and 96–99% cell viability. After 48 hours, G1-phase (diploid-2n) cells prevail in the cell population of the new subline (30.0–75.0% of cells); cells that undergo preparation for mitosis (S-phase) and mitosis (G2+M-phase) account for 3.0 to 20.0% of the entire population; the number of meganucleated and multinucleated cells (>4n) at the beginning and at the end of the logarithmic phase increases to 2%. BHK-21/SUSP/ARRIAH cells recover rapidly after cryopreservation and demonstrate 95–99% viability and growth rate of 3.36–5.88 at passages 1 to 3 and 6.85–10.95 at passages 4 to 12. Continuous suspension BHK-21/SUSP/ARRIAH cell line ensures virus accumulation at the following titres: FMD virus – 7.30– 8.00 lg TCID50/cm3, rabies virus – 7.25–8.00 lg CCID50/cm3, bovine parainflunza-3 virus – at least 6.00 lg TCID50/cm3, Aujeszky’s disease virus – 7.50–7.80 lg TCID50/cm3.

Anticoronavirus Activity of Water-Soluble Pristine C60 Fullerenes: In Vitro and In Silico Screenings.

The emergence of a new member of the Coronaviridae family, which caused the 2020 pandemic, requires detailed research on the evolution of coronaviruses, their structure and properties, and interaction with cells. Modern nanobiotechnologies can address the many clinical challenges posed by the COVID-19 pandemic. In particular, they offer new therapeutic approaches using biocompatible nanostructures with "specific" antiviral activity. Therefore, the nanosized spherical-like molecule (0.72 nm in diameter) composed of 60 carbon atoms, C60 fullerene, is of interest in terms of fighting coronaviruses due to its high biological activity. In here, we aim to evaluate the effectiveness of anticoronavirus action of water-soluble pristine C60 fullerene in the model and in vitro systems. As a model, apathogenic for human coronavirus, we used transmissible gastroenteritis virus of swine (TGEV), which we adapted to the BHK-21 cell culture (kidney cells of a newborn Syrian hamster). The shape and size of the particles present in C60 fullerene aqueous colloidal solution (C60FAS) of given concentration, as well as C60FAS stability (value of zeta potential) were studied using microscopic (STM, scanning tunneling microscopy, and AFM, atomic force microscopy) and spectroscopic (DLS, dynamic light scattering) methods. The cytopathic effect of TGEV was determined with the help of a Leica DM 750 microscope and the degree of monolayer changes in cells was assessed. The microscopy of the viral suspension was performed using a high resolution transmission electron microscope (HRTEM; JEM-1230, Japan). Finally, the search for and design of optimal possible complexes between C60 fullerene and target proteins in the structure of SARS-CoV-2 coronavirus, evaluation of their stability in the simulated cellular environment were performed using molecular dynamics and docking methods. It was found that the maximum allowable cytotoxic concentration of C60 fullerene is 37.5±3.0μg/ml. The investigated C60FAS reduces the titer of coronavirus infectious activity by the value of 2.00±0.08TCID50/ml. It was shown that C60 fullerene interacts directly with SARS-CoV-2 proteins, such as RdRp (RNA-dependent RNA polymerase) and 3CLpro (3-chymotrypsin-like protease), which is critical for the life cycle of the coronavirus and, thus, inhibits its functional activity. In both cases, C60 fullerene fills the binding pocket and gets stuck there through stacking and steric interactions. Pioneer in vitro study to identify the anticoronavirus activity of water-soluble pristine C60 fullerenes indicates that they are highly promising for further preclinical studies, since a significant inhibition of the infectious activity of swine coronavirus of transmissible gastroenteritis in BHK-21 cell culture was found. According to molecular modeling results, it was shown that C60 fullerene can create the stable complexes with 3CLpro and RdRp proteins of SARS-CoV-2 coronavirus and, thus, suppress its functional activity.

Miramistin effect on BHK-21 and PSGK-30 cell line proliferation and FMD virus reproduction in these cells

At present, Miramistin drug (benzyldimethyl [3-(myristoylamino) propyl] ammonium chloride monohydrate), which has a broad bactericidal effect, is used in veterinary practice. This antiseptic is active against most viruses, mycoplasmas, bacteria, fungi and protozoa. According to toxicometric parameters, Miramistin is classified as a low-hazard substance. Use of cell structures as test systems for assessing the toxicity of pharmacological substances instead of conventional tests on experimental animals allows us to better clarify the possible mechanism of the effect of the investigated substance. Since many types of mycoplasmas affect the genitourinary system organs, to assess the cytotoxicity of Miramistin kidney mammalian cells of various mammals can be used as test systems, in particular, the newborn Syrian hamster (VNK-21), Siberian mountain ibex (PSGK-30), and others. The possibility of using BHK-21 and PSGK-30 cell monolayer as test systems for assessing the baseline cytotoxicity of Miramistin was shown. When studying toxicity of the drug, the effect of its various concentrations on the cell morphology was studied, the number of viable cells and the total protein content were determined as an indicator of the cell mass increase. The results of a cytomorphological study indicate that the Miramistin maximum permissible concentration of for BHK-21 and PSGK-30 cell monolayer is 25 μg/cm3. The use of this antibacterial drug in higher concentrations caused the appearance and increased signs of endogenous intoxication and degeneration. When evaluating the proliferative activity of cells under the influence of the Miramistin antibiotic in different concentrations, it was found that increasing the dose to 50, 75, 100, 125, 150 μg/cm3 leads to decrease in the rate of cell growth compared to the control. The Miramistin content in the growth medium in an amount of up to 25 μg/cm3 did not affect the intensity of protein synthesis. Presence of Miramistin in the culture medium at the maximum permissible concentration causes a slight decrease in the reproduction of foot and mouth disease virus in BHK-21 and PSGK-30 cell cultures by 4.5 and 4.0%, respectively, compared with the control without antibiotic. Since mycoplasmas are the most common contaminants of cell cultures, further studies will be aimed at exploring the possibility of using Miramistin for decontamination of BHK-21 and PSGK-30 cell monolayers.

Удосконалення засобів діагностики та специфічної профілактики хвороби Тешена

The purpose. To update diagnostic means and methods of specific prophylaxis of Teshen disease according to recommendations of International epizootic bureau. Methods. Reference and production strains of Tesho-virus of pigs are used. Accumulation of viruses was carried out in re-vaccinating cultures of kidney cells of an embryo of pig and newborn Syrian hamster. In experiments they used virus neutralization reaction, immunofluorescence, immunoassay, enzyme-linked immunosorbent assay, polymerase chain reaction with reverse transcription. Results. Sets of diagnosticums of Teshen diseases and inactivated vaccine against it with the characteristics which considerably exceeding domestic and foreign analogues are created on the basis of new domestic strain Teschovirus A «Dneprovskii-34». Conclusions. Diagnostic means and methods of specific prophylaxis of Teshen disease are updated.

A Fortuitous Journey from a Model System to a Human Pathogen.

A Fortuitous Journey from a Model System to a Human Pathogen.

Structural and Functional Analysis of Murine Polyomavirus Capsid Proteins Establish the Determinants of Ligand Recognition and Pathogenicity.

Murine polyomavirus (MuPyV) causes tumors of various origins in newborn mice and hamsters. Infection is initiated by attachment of the virus to ganglioside receptors at the cell surface. Single amino acid exchanges in the receptor-binding pocket of the major capsid protein VP1 are known to drastically alter tumorigenicity and spread in closely related MuPyV strains. The virus represents a rare example of differential receptor recognition directly influencing viral pathogenicity, although the factors underlying these differences remain unclear. We performed structural and functional analyses of three MuPyV strains with strikingly different pathogenicities: the low-tumorigenicity strain RA, the high-pathogenicity strain PTA, and the rapidly growing, lethal laboratory isolate strain LID. Using ganglioside deficient mouse embryo fibroblasts, we show that addition of specific gangliosides restores infectability for all strains, and we uncover a complex relationship between virus attachment and infection. We identify a new infectious ganglioside receptor that carries an additional linear [α-2,8]-linked sialic acid. Crystal structures of all three strains complexed with representative oligosaccharides from the three main pathways of ganglioside biosynthesis provide the molecular basis of receptor recognition. All strains bind to a range of sialylated glycans featuring the central [α-2,3]-linked sialic acid present in the established receptors GD1a and GT1b, but the presence of additional sialic acids modulates binding. An extra [α-2,8]-linked sialic acid engages a protein pocket that is conserved among the three strains, while another, [α-2,6]-linked branching sialic acid lies near the strain-defining amino acids but can be accommodated by all strains. By comparing electron density of the oligosaccharides within the binding pockets at various concentrations, we show that the [α-2,8]-linked sialic acid increases the strength of binding. Moreover, the amino acid exchanges have subtle effects on their affinity for the validated receptor GD1a. Our results indicate that both receptor specificity and affinity influence MuPyV pathogenesis.

English

The aim of this study was to determine the content of phenolic compounds and flavonoids, the antibacterial, antioxidant and cytotoxicity activities of hydroethanolic extracts of root, stem, leaf and fruit of Euphorbia cotinifolia. Phytochemical screening was performed using spectrophotometric methods (phenolic and flavonoid content) and liquid cromatography. The antibacterial activity was determined by agar diffusion and broth microdilution technique. Additionally, antioxidant activity was determined by diphenylpicrylhydrazyl (DPPH) radical scavenging method and cytotoxicity by the MTT method using BHK-21 (newborn hamster’s kidney) cells. All extracts presented notable content of phenolic compounds, flavonoids and tannins. The high-performance liquid chromatography with photodiode array detection (HPLC-DAD) analysis showed higher concentration of phenolic compounds in dried leaves than in fresh leaves and it indicated the presence of caffeic acid. The extracts of leaf, stem, root and fruit showed activity against five gram-positive bacteria, six gram-negative bacteria and two yeasts, but not for mycobacterial. The highest antioxidant activity was exhibited in the extract of dried leaf (EC50 = 7.32 μg/ml). Extracts showed no cytotoxicity at the concentrations tested. All extracts showed antibacterial, antifungal and antioxidant activities, phenolic compounds, tannins and flavonoids. The results provided evidence that the studied plant might indeed be potential sources of natural antioxidant and antimicrobial agents. Key words: Euphorbia cotinifolia, antimibacterial, antioxidant, phenolic compounds, flavonoids.

Altered distribution of inhibitory interneurons in polymicrogyria

There is a high incidence of epilepsy in patients with polymicrogyria; however, the epileptogenic mechanisms are largely unknown. The density of parvalbumin-immunoreactive interneurons was evaluated in an experimental model of polymicrogyria, in order to assess the potential changes in the development of one population of inhibitory interneurons. Newborn hamsters received an intracerebral injection of ibotenate, and all injected animals showed abnormal cortical layers characterized by one or two microgyrus in the fronto-parietal cortex. A quantitative analysis revealed that the ratios of parvalbumin-immunoreactive neurons in total neurons were significantly reduced in the medial paramicrogyral area, and in the medial and central parts of microgyrus in comparison to that in the lateral part of microgyrus (P<0.01). The lateral paramicrogyral area had the greatest number of parvalbumin-immunoreactive neurons, which was increased significantly in comparison to that in the control cortex (P<0.01). We suggest that the callosal, thalamic and intracortical afferents to the microgyrus and paramicrogyral area may induce a remarkable imbalance between the excitatory and inhibitory activities of the cortical structures, associated with the epileptogenic mechanism in polymicrogyria.

Developmental Changes in the ECG of a Hamster Model of Muscular Dystrophy and Heart Failure

Aberrant autonomic signaling is being increasingly recognized as an important symptom in neuromuscular disorders. The δ-sarcoglycan-deficient BIO TO-2 hamster is recognized as a good model for studying mechanistic pathways and sequelae in muscular dystrophy and heart failure, including autonomic nervous system (ANS) dysfunction. Recent studies using the TO-2 hamster model have provided promising preclinical results demonstrating the efficacy of gene therapy to treat skeletal muscle weakness and heart failure. Methods to accelerate preclinical testing of gene therapy and new drugs for neuromuscular diseases are urgently needed. The purpose of this investigation was to demonstrate a rapid non-invasive screen for characterizing the ANS imbalance in dystrophic TO-2 hamsters. Electrocardiograms were recorded non-invasively in conscious ∼9-month old TO-2 hamsters (n = 10) and non-myopathic F1B control hamsters (n = 10). Heart rate was higher in TO-2 hamsters than controls (453 ± 12 bpm vs. 311 ± 25 bpm, P < 0.01). Time domain heart rate variability, an index of parasympathetic tone, was lower in TO-2 hamsters (12.2 ± 3.7 bpm vs. 38.2 ± 6.8, P < 0.05), as was the coefficient of variance of the RR interval (2.8 ± 0.9% vs. 16.2 ± 3.4%, P < 0.05) compared to control hamsters. Power spectral analysis demonstrated reduced high frequency and low frequency contributions, indicating autonomic imbalance with increased sympathetic tone and decreased parasympathetic tone in dystrophic TO-2 hamsters. Similar observations in newborn hamsters indicate autonomic nervous dysfunction may occur quite early in life in neuromuscular diseases. Our findings of autonomic abnormalities in newborn hamsters with a mutation in the δ-sarcoglycan gene suggest approaches to correct modulation of the heart rate as prevention or therapy for muscular dystrophies.

Melatonin inhibits glucocorticoid-dependent GR–TIF2 interaction in newborn hamster kidney (BHK) cells

The antagonism exerted by melatonin on the glucocorticoid response has been well established, being strongly dependent on the cellular context. Previously, we found that melatonin inhibits glucocorticoid receptor (GR) dissociation from the chaperone hetero-complex and nuclear translocation on mouse thymocytes. Here, by performing confocal fluorescence microscopy and the Number and Brightness assay we show that in newborn hamster kidney cells (BHK21) melatonin neither affects GR nuclear translocation nor GR homodimerization. Instead, co-immunoprecipitation studies suggest that physiological concentrations of melatonin impair GR interaction with the transcriptional intermediary factor 2 (TIF2). This melatonin effect was not blocked by the MT1/MT2 receptor antagonist luzindole. Curiously, luzindole behaved as an antiglucocorticoid per se by impairing the glucocorticoid-dependent MMTV-driven gene expression affecting neither GR translocation nor GR–TIF2 interaction.

Experimental Neuronal Migration Disorders Following the Administration of Ibotenate in Hamsters: The Role of the Subventricular Zone in the Development of Cortical Dysplasia

To examine the role of subventricular zone in cortical dysplasia, an experimental model was established using a neuronal tracing study. Ibotenate is a glutamate receptor agonist, and its intracerebral injection produces excitotoxic lesions mimicking microgyria and heterotopia. A total of 72 newborn hamsters were subjected. Biotinylated dextran amine was injected into the ganglionic eminence for the neuronal tracer. The cortical lesions and apoptotic cells were analyzed. In the microgyric cortex, terminal deoxynucleotidyl transferase-mediated 2' -deoxyuridine 5'-triphosphate-biotin end labeling-positive cells were increased and accumulated in the cortical folding. Biotinylated dextran amine-positive cells and fibers were derived from the dorsolateral subventricular zone and directed toward the cortical folding. In the heterotopic cortex, terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine 5'-triphosphate- biotin end labeling-positive cells were distributed around the heterotopia, but number of cells was not remarkable. Our findings suggest that the subventricular zone plays an important role in the formation of cortical dysplasia, especially in the microgyria, after excitatory neuronal injury.

A new cell line derived from newborn Chinese hamster lung tissue.

A new cell line derived from newborn Chinese hamster lung tissue.

Neuroendocrine Effects in Reproductive Aging Assessed by Newborn Hamster Testicular Xenografting into Aged Nude Mouse Hosts.

Neuroendocrine Effects in Reproductive Aging Assessed by Newborn Hamster Testicular Xenografting into Aged Nude Mouse Hosts.

Ectopic testicular xenografts from newborn hamsters (Phodopus sungorus) show better spermatogenic activity in aged compared with young recipients

The mechanisms behind testicular aging are poorly understood. Previous studies suggest that the testicular microenvironment is more affected by age than the male germ cell lineage. Here we analyze male reproductive aging using a unique xenografting approach. By exposing young and aged mice to newborn hamster testicular tissue, we can explore (a) whether the development and endocrine activity of hamster testicular grafts and the initiation of stem cell activity within them are affected by age of the recipients and (b) whether the endocrine response to the xenografted hamster tissue varies with recipient age. Newborn Djungarian hamster (Phodopus sungorus) testes were grafted into young (12 weeks) and aged (1 year) adult castrated nude mice. We also analyzed intact and castrated young and old control groups. After 13 weeks, 100 grafts were recovered from a total of 15 recipients and were histologically analyzed. Anatomical and endocrine parameters were recorded for each recipient as well as for the controls. Xenografted recipients responded with a normalization of their endocrine and anatomical parameters to an extent typical for their age. Although recipient age did not significantly affect graft survival and size, histopathological changes as well as spermatogenic damage within the grafts were more pronounced in the young recipients (56% Sertoli-cell-only tubules vs. 32% in the old recipients). We conclude from our data that the androgen-related changes associated with male reproductive aging are not primarily controlled by the testis. We speculate that the better development of testicular grafts in aged recipients may be owing to immunosenescence.

Infection: Is it a cause of bladder cancer?

This article reviews the literature regarding the possible correlation between infection and occurrence of bladder cancer. The PubMed literature database was searched from inception to January 2008. Keywords of bladder, cancer, parasitic, bacterial, viral and infection, were used. Forty studies were included in the review. Several investigators support the idea that schistosomiasis is aetiologically related to the development of bladder cancer in individuals infected with Schistosoma haematobium. Approximately 70% of those with chronic schistosomiasis who have bladder cancer develop squamous cell rather than transitional cell carcinoma. Several investigators suggest that bacteria may play a role in inducing bladder cancer. Clinically, researchers have linked the development of infection, urinary stones and indwelling catheters with bladder cancer. Nevertheless, to date, no prospective study has examined the association between urinary tract infection and bladder cancer risk. The possibility that infection by human papilloma virus (HPV) is a risk factor contributing to bladder cancer has been investigated but no definite conclusions have been drawn. Thus, the debate remains open as to whether there is any direct link between chronic HPV infection and bladder cancer. Only 15 cases of vesical carcinoma have been reported, to date, in the setting of human immunodeficiency virus (HIV). The rare occurrence of bladder cancer during HIV infection and the lack of correlation with the laboratory markers of HIV disease progression may suggest a trivial association between two unrelated disorders. BK virus is oncogenic in newborn hamsters and can transfer to mammalian cells in vitro, but there is little consistent evidence of a link with human bladder cancer. Studies showed no correlation between herpes simplex virus (HSV) and bladder cancer, but bladder cancer becomes infected with HSV much more easily than non-neoplastic urothelium. In conclusion, with the exception of chronic infection with S. haematobium, the association between the occurrence of bladder cancer and chronic bacterial or viral infections could not be confirmed. Prospective studies with large numbers of patients and controls are required to confirm this issue.

Hepatobiliary effects of cholic and lithocholic acids: experimental study in hamsters

Etiopathogenesis of biliary atresia remains unknown. Among several theories, one proposes that the disorder may be caused by the toxic effect of monohydroxy bile acids on fetal and neonatal hepatobiliary system. In this paper we evaluated toxic effects produced by ingestion of cholic acid, a trihydroxy bile acid, and lithocholic acid, a monohydroxy bile acid in the hepatobiliary system of a hamster during gestational and perinatal periods. A diet composed by 0.5% cholic acid and 0.25% lithocholic acid was administrated to pregnant hamsters. Liver and bile ducts of the adult and newborn animals were analyzed to point out the changes induced by these acids after birth. Because hamsters and humans have a similar bile metabolism, these animals were eligible for the study. The ingestion of 0.5% lithocholic acid, during hamster's gestation, caused maternal intense ductal/ductular proliferation, inflammatory signs, hepatic cells degeneration and regeneration, hyperplasia of extra hepatic ducts epithelium, and abortion. Both 0.5% cholic acid and 0.25% lithocholic acid ingested by pregnant hamsters, caused ductal/ductular proliferation and hepatobiliary inflammatory damage in a different degree of intensity in adult animals and mild intensity in the young; and also the number of the young was reduced in the litter. We found that the ingestion of these bile acids by hamsters, during gestational period caused different degrees of toxicity on maternal and neonatal hepatobiliary systems. The histopathologic findings observed in biliary atresia patients could not be found in newborn hamsters. New experimental models are needed in the attempt to establish a correlation of these acids with neonatal cholestatic diseases.

Enteric adenoviruses.

The 41 serotypes of human adenoviruses are classified into six subgenera (A-F) with different tropisms. Enteric infections are caused in children by serotypes Ad40 and Ad41 of subgenus F. Serotypes Ad40 and Ad41 transform embryonic cells but cannot induce tumours in newborn hamsters. They differ from all other (established) human adenoviruses by being unable to replicate in conventional cell cultures. Ad40 and Ad41 grow in 293 cells (human embryonic kidney cells immortalized by transfection with the E1A, E1B regions of Ad5). In spite of the difficulty of isolating Ad40 and Ad41 they can be directly identified in stools by enzyme-linked immunosorbent assay (ELISA) and solid-phase immuno-electron microscopy. The amount of viral DNA in stool preparations is sufficient for identification by DNA restriction or dot-blot analysis. Adenoviruses have been associated with 7-17% of cases of diarrhoea in children. Ad40 and Ad41 cause diarrhoea throughout the year. Clinical features are watery stools, vomiting and moderately elevated temperature; respiratory symptoms are infrequent. The diarrhoea is protracted (mean 8.6 and 12.2 days for Ad40 and Ad41 respectively). Children with rotavirus diarrhoea vomited more frequently and had a higher temperature and diarrhoea of shorter duration. The impact of enteric adenoviruses in the aetiology of diarrhoea world-wide is not known but is accessible to investigation.

Cross-species infectivity and pathogenesis of the Friend murine leukemia virus complex in Syrian hamsters

To investigate cross-species infectivity and pathogenesis of Friend murine leukemia virus (MuLV) in hamsters, we infected newborn Syrian hamsters with ecotropic Friend MuLV that was passaged in BALB/c mice for approximately 30 years. During acute infection, 39.5% of newborn Syrian hamsters developed severe growth interruption and weight loss, spleen atrophy, severe lymphocyte depletion, and massive viral antigen loads in the spleen. The lymph nodes and thymuses were observed in all diseased hamsters. Ecotropic Friend MuLV was rescued from the sera and spleen and heart extracts of the diseased hamsters, and the same disease was confirmed by induction of erythroleukemia in BALB/c mice. Our results demonstrate that an ecotropic MuLV after extended passage in vivo to infect hamster cells that are resistant to infection by wild type MuLV, causing pathologic lesions and a wasting syndrome in newborn hamsters in vivo. This may occur with variants of Friend MuLV that have lower infectivity in hamster cells and are not cleared by the immune system of newborn hamsters. These findings suggest the potential danger of the interspecies transmission and pathogenesis of heterologous retroviruses in humans.

Cell-based fluorescence assay for evaluation of new-drugs potential for phospholipidosis in an early stage of drug development

To evaluate new-drugs potential for phospholipidosis (PL), we developed a cell-based fluorescence assay using a fluorescent-labeled phospholipid analogue (NBD-PE). CHL/IU cells derived from newborn hamster lung were exposed to positive reference compounds (amiodarone, imipramine, chloroquine, propranolol, chlorpromazine and amantadine) in the presence of NBD-PE, and the level of PL, as indicated by accumulation of fluorescent inclusions in the cytoplasm, was evaluated using fluorescence microscopy and fluorometry. All positive reference compounds induced accumulation of fluorescent inclusions in a concentration-dependent manner with an increase in fluorescence intensity. Fluorescence microscopically, the positive dose of test compound was determined as the concentration with a grade equivalent to or above that of 3.13 μM of amiodarone. Based on this criterion, 8 of 20 test compounds including PL-positive or -negative compounds were judged positive that were concurrent with the pathological results from rat toxicity studies. Furthermore, a positive criterion for fluorometry was decided as equivalent to or above 25% of maximum intensity induced by 1.56–25.0 μM amiodarone. In comparison of fluorometry methods with fluorescence microscopy method, 19 of 20 compounds were judged same. From these findings, we concluded that the assay developed in this study is a rapid and reliable method to predict new-drugs potential for PL at an early stage of drug development.