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Therapeutic dosing with anti-interleukin-13 monoclonal antibody inhibits asthma progression in mice.

In vivo models have demonstrated that interleukin-13 (IL-13) plays an important role in asthma; however, few studies have evaluated the effect of inhibition of IL-13 on established and persistent disease. In the present study, we have investigated the effect of a therapeutic dosing regimen with an anti-IL-13 monoclonal antibody (mAb) in a chronic mouse model of persistent asthma. BALB/c mice were sensitized to allergen [ovalbumin (OVA); on days 1 and 8] and challenged with OVA weekly from day 22. Anti-IL-13 mAb or vehicle dosing was initiated following two OVA challenges when disease was established. At this time, mice exhibited airway hyperresponsiveness (AHR), increased mucus production, inflammation, and initiation of subepithelial fibrosis compared with saline-challenged mice. Mice received four additional OVA challenges. Treatment with anti-IL-13 mAb inhibited AHR and prevented the further development of subepithelial fibrosis and progression of inflammation. Furthermore, mAb treatment reversed the mucus hyperplasia to basal levels. These effects were associated with an inhibition of cytokines, chemokines, and matrix metalloproteinase-9. These data demonstrate that neutralization of IL-13 can inhibit the progression of established disease in the presence of repeated allergen exposures.

Animals↗

Colonization and infection of athymic and euthymic germfree mice by Campylobacter jejuni and Campylobacter fetus subsp. fetus.

Human clinical strains of Campylobacter jejuni and Campylobacter fetus subsp. fetus colonized the gastrointestinal tracts of both athymic (nu/nu) and euthymic (+/nu) germfree mice (BALB/c). Viable Campylobacter spp. (10(9) to 10(10) CFU/g [dry weight] of cecum and colon contents) were isolated on day 3 after oral challenge, and similar large numbers of viable cells were evident at several intervals during a 10-month experiment. The stomachs and upper small intestines of nu/nu and +/nu mice that were monoassociated for 224 days with C. jejuni 45100 contained 3 to 4 logs fewer viable bacteria than did their ceca or colons. Athymic mice that were monoassociated for 224 days with C. fetus subsp. fetus had 2 to 3 logs more viable Campylobacter spp. in their upper gastrointestinal tracts than did their +/nu littermates. Large viable populations (approximately 10(9)/g of contents) of C. fetus subsp. fetus were in the ceca and colons of both nu/nu and +/nu mice. All C. jejuni strains used in this study chronically infected the mesenteric lymph nodes of both nu/nu and +/nu mice. C. jejuni strains 24 and INN 73-83, which were cytotoxic for Chinese hamster ovary cells in vitro, were also more frequently isolated from the livers, spleens, and kidneys of nu/nu mice than was the weak cytotoxin-producing strain 45100. Additionally, heat-labile-enterotoxin-producing C. jejuni INN 73-83 was recovered more frequently from the internal organs of monoassociated +/nu mice than were any other Campylobacter spp. tested. Natural gastrointestinal colonization of neonatal nu/nu and +/nu mice (born to Campylobacter-colonized mothers) with Campylobacter spp. appeared to be delayed until approximately 1 to 2 weeks after birth. Conventionalization of C. jejuni 45100-monoassociated BALB/c mice with a complex mouse fecal microflora eliminated viable C. jejuni from the mesenteric lymph nodes by day 14 and from the cecum by day 78. These findings show that the gnotobiotic BALB/c mouse is a new model for studying acute and chronic host-Campylobacter sp. interactions.

Animals↗

Influence of immunization on Porphyromonas gingivalis colonization and invasion in the mouse chamber model.

The effects of immunization with invasive or noninvasive Porphyromonas (Bacteroides) gingivalis strains on the pathogenesis of infection in a mouse chamber model were examined. BALB/c mice were immunized by a single injection of heat-killed P. gingivalis invasive strain A7436 or W83 or noninvasive strain 33277, HG405, or 381 directly into subcutaneous chambers. P. gingivalis-specific antibody was detected in chamber fluid 21 days postimmunization, and mice were subsequently challenged by injection of exponential-phase P. gingivalis into chambers. Immunization with A7436 or W83 followed by challenge with A7436 protected mice against secondary abscess formation and death; however, P. gingivalis persisted in chambers for up to 14 days postchallenge. Immunization with noninvasive strain 33277, HG405, or 381 followed by challenge with invasive strain A7436 or W83 protected mice against secondary lesion formation and death. P. gingivalis was cultured from 33277- or HG405-immunized and nonimmunized animals to day 14. All P. gingivalis strains induced an immunoglobulin G response, as measured by an enzyme-linked immunosorbent assay and Western immunoblotting of P. gingivalis whole-cell and outer membrane protein preparations. Western blot analyses indicated that sera from mice immunized with different invasive and noninvasive strains recognized common P. gingivalis antigens. In summary, immunization with invasive P. gingivalis A7436 and W83 or noninvasive P. gingivalis 33277, HG405, and 381 protected mice from secondary lesion formation and death after challenge with invasive P. gingivalis A7436 or W83. P. gingivalis-specific antibody did not, however, inhibit the colonization of P. gingivalis within chambers.

Animals↗

Role of the Helicobacter pylori virulence factors vacuolating cytotoxin, CagA, and urease in a mouse model of disease.

The pathogenic role of Helicobacter pylori virulence factors has been studied with a mouse model of gastric disease. BALB/c mice were treated orally with different amounts of sonic extracts of cytotoxic H. pylori strains (NCTC 11637, 60190, 84-183, and 87A300 [CagA+/Tox+]). The pathological effects on histological sections of gastric mucosae were assessed and were compared with the effects of treatments with extracts from noncytotoxic strains (G21 and G50 [CagA-/Tox-]) and from strains that express either CagA alone (D931 [CagA+/Tox-]) or the cytotoxin alone (G104 [CagA-/Tox+]). The treatment with extracts from cytotoxic strains induced various epithelial lesions (vacuolation, erosions, and ulcerations), recruitment of inflammatory cells in the lamina propria, and a marked reduction of the mucin layer. Extracts of noncytotoxic strains induced mucin depletion but no other significant pathology. Crude extracts of strain D931, expressing CagA alone, caused only mild infiltration of inflammatory cells, whereas extracts of strain G104, expressing cytotoxin alone, induced extensive epithelial damage but little inflammatory reaction. Loss of the mucin layer was not associated with a cytotoxic phenotype, since this loss was observed in mice treated with crude extracts of all strains. The pathogenic roles of CagA, cytotoxin, and urease were further assessed by using extracts of mutant strains of H. pylori defective in the expression of each of these virulence factors. The results obtained suggest that (i) urease activity does not play a significant role in inducing the observed gastric damage, (ii) cytotoxin has an important role in the induction of gastric epithelial cell lesions but not in eliciting inflammation, and (iii) other components present in strains which carry the cagA gene, but distinct from CagA itself, are involved in eliciting the inflammatory response.

Animals↗

Inducible immunity to Trichomonas vaginalis in a mouse model of vaginal infection.

We studied the protective effect of subcutaneous immunization with Trichomonas vaginalis in a mouse model of vaginal infection. BALB/c mice were immunized with various doses of T. vaginalis (4.5 x 10(5), 9 x 10(6), and 1 x 10(8) organisms per ml) suspended in Freund's complete adjuvant 56 days prior to vaginal infection and were given booster injections of the same doses of T. vaginalis in Freund's incomplete adjuvant 4 weeks later. Control mice were immunized and given booster injections of phosphate-buffered saline suspended in Freund's complete and incomplete adjuvants. The mice were tail bled and vaginal washes were performed at weekly intervals for 4 weeks to determine the isolation of T. vaginalis and the serum and vaginal antibody reactivity. Mice which had been immunized and given booster immunizations had significantly fewer intravaginal infections and had increased serum and vaginal antibody responses compared with those of control mice (P < 0.01). Mice that were vaginally infected, treated with metronidazole, and then reinfected vaginally did not develop protective immunity. Subcutaneous immunization with whole T. vaginalis organisms appears to confer protection against intravaginal challenge with T. vaginalis, protection which is not achieved as a result of prior vaginal infection.

Animals↗

Quorum sensing: a transcriptional regulatory system involved in the pathogenicity of Burkholderia mallei.

Numerous gram-negative bacterial pathogens regulate virulence factor expression by using a cell density mechanism termed quorum sensing (QS). An in silico analysis of the Burkholderia mallei ATCC 23344 genome revealed that it encodes at least two luxI and four luxR homologues. Using mass spectrometry, we showed that wild-type B. mallei produces the signaling molecules N-octanoyl-homoserine lactone and N-decanoyl-homoserine lactone. To determine if QS is involved in the virulence of B. mallei, we generated mutations in each putative luxIR homologue and tested the pathogenicities of the derivative strains in aerosol BALB/c mouse and intraperitoneal hamster models. Disruption of the B. mallei QS alleles, especially in RJ16 (bmaII) and RJ17 (bmaI3), which are luxI mutants, significantly reduced virulence, as indicated by the survival of mice who were aerosolized with 10(4) CFU (10 50% lethal doses [LD50s]). For the B. mallei transcriptional regulator mutants (luxR homologues), mutation of the bmaR5 allele resulted in the most pronounced decrease in virulence, with 100% of the challenged animals surviving a dose of 10 LD50s. Using a Syrian hamster intraperitoneal model of infection, we determined the LD50s for wild-type B. mallei and each QS mutant. An increase in the relative LD50 was found for RJ16 (bmaI1) (>967 CFU), RJ17 (bmaI3) (115 CFU), and RJ20 (bmaR5) (151 CFU) compared to wild-type B. mallei (<13 CFU). These findings demonstrate that B. mallei carries multiple luxIR homologues that either directly or indirectly regulate the biosynthesis of an essential virulence factor(s) that contributes to the pathogenicity of B. mallei in vivo.

4-Butyrolactone↗

Type III secretion: a virulence factor delivery system essential for the pathogenicity of Burkholderia mallei.

By creating mutations in the Burkholderia mallei ATCC 23344 animal pathogen-like type III secretion system (TTSS), this study analyzes the correlation between type III secretion and the pathogenicity of ATCC 23344 in vivo. Mutagenesis demonstrated that a functional TTSS was required for the full pathogenicity of ATCC 23344 in the BALB/c mouse and Syrian hamster models of infection. However, vaccination with each mutant failed to elicit a protective immunity against challenge with wild-type ATCC 23344.

Animals↗

Growth factor upregulation during obliterative bronchiolitis in the mouse model.

Obliterative bronchiolitis (OB), or chronic allograft rejection, is a major cause of morbidity and mortality after lung transplantation. The goal of these experiments was to determine whether several important growth factors were upregulated during OB in the mouse heterotopic trachea model. Isografts (BALB/c into BALB/c) and allografts (BALB/c into C57BL/6) were implanted in three sets of cyclosporine-treated animals and were harvested from 2 to 10 weeks. Ribonucleic acid was isolated using the cesium chloride-guanidine method and was reverse transcribed and semiquantitated with the polymerase chain reaction using specific primers for platelet-derived growth factor (PDGF)-A and PDGF-B chains, fibroblast growth factor (FGF) isoforms 1 and 2, transforming growth factor-beta, tumor necrosis factor-alpha (TNF-alpha), edothelin-1, (prepro) epidermal growth factor, insulin-like growth factor-1, and beta-actin as a control. Transforming growth factor-beta, TNF-alpha, endothelin-1, and insulin-like growth factor-1 expression were increased 1.5-fold to 5.0-fold (p < or = 0.04 for each) in the allografts compared with the isografts at Weeks 2 through 6. Significantly increased expression of FGF-1, FGF-2, and PDGF-B was noted in the allografts at 4 weeks (p < 0.05 for each), which reversed at 6 and 10 weeks. No differences were found with the PDGF-A chain. The isografts expressed more epidermal growth factor than allografts (p < 0.001). Treatment with a TNF-alpha-soluble receptor (human TNFR:Fc) significantly reduced epithelial injury (p = 0.01) and lumenal obstruction (p = 0.037) in this model. We conclude that increased expression of a large number of growth factors occurs during OB in this model. Growth factor blockade (in particular with regard to TNF-alpha) may be useful in ameliorating OB in this model.

Animals↗

Lesions of experimental genital Tritrichomonas foetus infections in estrogenized BALB/c mice.

Ninety-seven BALB/c mice were inoculated intravaginally with 8.0 x 10(5) Tritrichomonas foetus organisms, using either isolate ATCC 30003 or field isolate MU Y22 2 days after estrogenization with 15 micrograms 17 beta-estradiol. Reproductive tracts were examined at several time points post-inoculation to determine gross and histologic responses to trichomonad infection as compared to estrogenized, uninfected control animals. The two isolates varied greatly in ability to maintain chronic infection; no ATCC 30003-inoculated animals remained culture-positive beyond 7 weeks post-inoculation, whereas MU Y22-inoculated animals were infected for greater than 26 weeks. Lesions were seen in 40-60% of animals prior to 10 weeks post-inoculation and included moderate uterine dilation and glandular atrophy, uterine gland abscesses, pyometra, intramural perivascular lymphoid infiltrates, and ovarian bursitis. The severity of lesions was independent of the T. foetus isolate. Lesions became more severe at 10 weeks post-inoculation, and at 10 and 26 weeks post-inoculation, lesions were seen in 60% and 75% of animals, respectively. In addition to lesions described above, epithelial changes were marked at these late necropsies, including ulceration, flattening, hypertrophy, and squamous metaplasia. The lesions seen in these mice closely resemble those described in natural bovine infection, suggesting that the estrogenized BALB/c mouse is an excellent model for study of bovine trichomoniasis.

Administration, Intravaginal↗

New bone formation induced by injection of native reindeer bone morphogenetic protein extract.

BACKGROUND AND AIMS: Bone morphogenetic proteins (BMPs) are usually administered with a solid framing material during open surgery. In some instances, percutaneous administration of injectable BMP would be preferable. We tested the new bone-forming activity of injectable native reindeer BMP extract in the Balb/C mouse thigh muscle pouch model. MATERIALS AND METHODS: The injectable implants contained 6 mg of native reindeer BMP extract and either physiological saline (NaCl/BMP) or collagen (Gel/BMP). Corresponding implants without BMP served as controls. New bone formation was evaluated based on incorporation of Ca45 and radiographically three weeks after the injection into the mouse thigh muscles. RESULTS: None of the injections without BMP were able to induce new bone visible in radiographs, whereas the injections with BMP induced new bone effectively. There were no significant differences in the area of new bone (p = 0.247) and its density (p = 0.739) between the NaCl/BMP and Gel/BMP groups. Ca-45 incorporation was multifold in the NaCl/BMP and Gel/BMP groups compared to the controls (p = 0.000). No significant differences in Ca-45 incorporation (p = 0.739) between the NaCl/BMP and Gel/BMP groups were observed. CONCLUSION: Our results suggest that BMP can be administered percutaneously, and that collagen and physiological saline are equally good carriers of injectable implants of native reindeer BMP.

Animals↗

Gamma irradiation and ethylene oxide in the sterilization of native reindeer bone morphogenetic protein extract.

BACKGROUND AND AIMS: For human use, it is necessary to sterilize bone morphogenetic proteins (BMPs), in order to reduce the risk of infections and associated complications. We compared the effects of ethylene oxide and gamma irradiation in the sterilization of native reindeer BMP extract with regard to bone induction in the Balb/C mouse thigh muscle pouch model. MATERIALS AND METHODS: BMP extract, sterilized with ethylene oxide gas (Steri-Vac 4XL, temperature 29 degrees C, exposure time 4 h, ethylene oxide concentration 860 mg/l), or gamma irradiation at doses of 3.15 MRad was administered in implants containing 5 or 10 mg of BMP extract with collagen carrier. Non-sterilized collagen implants served as controls. New bone formation was evaluated based on the incorporation of Ca45 and radiographically three weeks after implantation. RESULTS: The collagen was not able to induce new bone visible in radiographs. The mean Ca45 incorporation in the gamma sterilized group containing 5 mg of BMP extract was 30% (p = 0.04) and that containing 10 mg of BMP extract was 60% (p = 0.02) higher than seen in the corresponding ethylene oxide sterilized groups. The mean new bone areas were 45% higher in the gamma sterilized groups than in the corresponding ethylene oxide sterilized groups, but the differences were not significant. The mean optical density of new bone in the gamma sterilized group containing 5 mg of BMP extract was 75% (p = 0.00) and in that containing 10 mg of BMP extract was 70% (p = 0.00) higher than seen in the corresponding ethylene oxide sterilized groups. CONCLUSION: Native reindeer BMP extract is more sensitive to the effects of ethylene oxide gas sterilization than gamma irradiation. These results suggest that gamma irradiation is recommendable for the sterilization of BMP extracts.

Animals↗

UVB exposure impairs immune responses after hepatitis B vaccination in two different mouse strains.

Ultraviolet light exposure can impair immune responses that are not restricted to the exposed skin but is also found at other sites, i.e. systemic immunosuppression. Therefore, we investigated the UV-induced modulating effects on vaccination against hepatitis B in a mouse model. Two different mouse strains, BALB/c and C57B1/ 6, were vaccinated intramuscularly against hepatitis B. Mice were exposed to different doses of ultraviolet B (UVB) for five consecutive days on shaved back skin before the vaccination. Vaccination against hepatitis B induced cellular (delayed-type hypersensitivity [DTH] and lymphocyte stimulation test) as well as humoral immune responses in both mouse strains. The DTH responses in C57BB1/6 mice were statistically significantly higher compared with BALB/c mice. UVB exposure induced a dose-dependent suppression of cellular immunity in both strains of mice. C57B1/6 mice seemed to be more susceptible to this suppression. Anti-hepatitis B surface antibodies (total-Ig) were only marginally suppressed after UVB exposure. IgG2a and interferon-gamma levels, both indicators for Th1 immune response, were suppressed in both mouse strains after UVB exposure. In summary, UVB exposure induced a dose-dependent suppression of both cellular and humoral immune responses after hepatitis B vaccination, although the suppressive effects on humoral immunity were limited to IgG2a production. Susceptibility to UVB-induced immunomodulation depended on the strain of mice and their predilection for developing different T cell responses.

Animals↗

Vinca alkaloid skin toxicity: antidote and drug disposition studies in the mouse.

A murine (BALB/c) skin toxicity model was used to evaluate various possible antagonists to vinca alkaloid-induced skin ulceration. Reproducible dose-response relationships were developed for vinblastine (VBL) and vindesine (VDS). With vincristine (VCR) only about 70% of mice developed dose-dependent ulceration. On an equal weight basis, VCR proved to be significantly more toxic than either VBL or VDS (P less than .05 by Student's t-test). Effective local intradermal antidotes to VBL, VDS, and VCR included hyaluronidase, normal saline, and calcium leucovorin (P less than .05 by the Student's Newman-Keuls multiple range test). Mild, topical skin heating significantly reduced VCR ulceration. In contrast, diphenhydramine and sodium bicarbonate were ineffective as local antidotes. Topical skin cooling, however, significantly increased vinca-induced skin ulcers for VBL, VDS, and VCR (P less than .05). Hydrocortisone, vitamin A topical cream, and isoproterenol increased skin toxicity. [3H]VBL was given intradermally to follow the drug's pharmacokinetic disposition from the skin and adherent panniculus carnosus muscle. [3H]VBL exhibited two phases of elimination: a rapid early phase [half-life (t 1/2) of approximately equal to 30 min] and a prolonged terminal phase (t 1/2 of approximately equal to 17 hr). The application of heat increased the distributive, early phase by 0.5-2.5 hours and did not enhance the terminal elimination of the drug from skin. Intradermal hyaluronidase significantly reduced the area under the ulceration multiplied by the time curve to one-seventh the control value, the peak [3H]VBL skin concentration to one-half the control value and the terminal [3H]VBL t 1/2 in skin to one-third the control level (P less than .05 by Student's t-test). These results show hyaluronidase to be an effective antidote for vinca-induced skin ulceration. Local glucocorticosteroids and topical cooling are definitely contraindicated in the management of inadvertent vinca alkaloid extravasations.

Administration, Topical↗

THNLA-1 as radio/chemosensitiser of EMT-6 tumours in mice.

THNLA-1 contains a 2-nitroimidazole tethered to 9-amino-1,2,3,4-tetrahydroacridine. Compared with its parent acridinic analogue, NLA-1, THNLA-1 is a weak DNA-affinic bioreductive compound with a greater mobility along the DNA backbone, decreased aerobic toxicity, greater hypoxic selectivity and a superior in vitro therapeutic index. Also, THNLA-1 behaves as a radio/chemosensitiser in vitro. In this report we have expanded our radio/chemosensitisation studies in vivo, using the EMT-6 mouse mammary tumour model in balb/c mice and the in vivo-in vitro assay. THNLA-1 was given i.p. ( < or = 0.5 ml in saline) at various time intervals before a single dose of 20 Gy whole-body irradiation. Tumours were excised immediately or 24 h after irradiation. Radiosensitisation studies with SR-2508 (i.v.) have been performed in a similar way for comparison purposes. THNLA-1 demonstrated the same radiosensitising effect as SR-2508 but with 19-fold less dose (mmol kg-1). The optimum effect was observed when THNLA-1 was given 1 h before irradiation and the tumours excised 24 h after irradiation. Chemosensitisation studies in the same tumour model and using cis DDP showed that the cytotoxic effect of cis-DDP (5 or 8 mg kg-1, i.p.) was significantly enhanced with 30 or 45 mg kg-1 THNLA-1 given approximately 3 h before cis-DDP. A similar potentiating effect was observed when NLA-1 (27 or 30 mg kg-1) was used, but toxicity was also observed at the higher dose. Limited toxicity studies showed that THNLA-1 is well tolerated up to at least 70 mg kg-1 as a single dose, for more than 40 days.

Animals↗

Oral efficacy of a respiratory syncytial virus inhibitor in rodent models of infection.

BMS-433771 is a potent inhibitor of respiratory syncytial virus (RSV) replication in vitro. Mechanism of action studies have demonstrated that BMS-433771 halts virus entry through inhibition of F protein-mediated membrane fusion. BMS-433771 also exhibited in vivo efficacy following oral administration in a mouse model of RSV infection (C. Cianci, K. Y. Yu, K. Combrink, N. Sin, B. Pearce, A. Wang, R. Civiello, S. Voss, G. Luo, K. Kadow, E. Genovesi, B. Venables, H. Gulgeze, A. Trehan, J. James, L. Lamb, I. Medina, J. Roach, Z. Yang, L. Zadjura, R. Colonno, J. Clark, N. Meanwell, and M. Krystal, Antimicrob. Agents Chemother. 48:413-422, 2004). In this report, the in vivo efficacy of BMS-433771 against RSV was further examined in the BALB/c mouse and cotton rat host models of infection. By using the Long strain of RSV, prophylactic efficacy via oral dosing was observed in both animal models. A single oral dose, administered 1 h prior to intranasal RSV inoculation, was as effective against infection as a 4-day b.i.d. dosing regimen in which the first oral dose was given 1 h prior to virus inoculation. Results of dose titration experiments suggested that RSV infection was more sensitive to inhibition by BMS-433771 treatment in the BALB/c mouse host than in the cotton rat. This was reflected by the pharmacokinetic and pharmacodynamic analysis of the efficacy data, where the area under the concentration-time curve required to achieve 50% of the maximum response was approximately 7.5-fold less for mice than for cotton rats. Inhibition of RSV by BMS-433771 in the mouse is the result of F1-mediated inhibition, as shown by the fact that a virus selected for resistance to BMS-433771 in vitro and containing a single amino acid change in the F1 region was also refractory to treatment in the mouse host. BMS-433771 efficacy against RSV infection was also demonstrated for mice that were chemically immunosuppressed by cyclophosphamide treatment, indicating that compound inhibition of the virus did not require an active host immune response.

Animals↗

A new model of busulphan-induced chronic bone marrow aplasia in the female BALB/c mouse.

Aplastic anaemia (AA) is characterized by hypocellular marrow, pancytopenia, and risk of severe anaemia, haemorrhage and infection. AA is often idiopathic, but frequently occurs after exposure to drugs/chemicals. However, the pathogenesis of AA is not clearly understood, and there are no convenient animal models of drug-induced AA. We have evaluated regimens of busulphan (BU) administration in the mouse to produce a model of chronic bone marrow aplasia showing features of human AA. Mice were given 8 doses of BU at 0, 5.25 and 10.50 mg/kg over 23 days; marrow and blood samples were examined at 1, 19, 49, 91 and 112 days after dosing. At day 1 post dosing, in mice treated at 10.50 mg/kg, nucleated marrow cells, CFU-GM and Erythroid-CFU were reduced. Similarly, peripheral blood erythrocytes, leucocytes, platelets and reticulocytes were reduced. At day 19 and 49 post dosing, there was a trend for parameters to return towards normal. However, at day 91 and 112 post dosing, values remained significantly depressed, with a stabilized chronic bone marrow aplasia. At day 91 and 112 post dosing, marrow cell counts, CFU-GM and Erythroid-CFU were decreased; marrow nucleated cell apoptosis and c-kit+ cell apoptosis were increased; peripheral blood erythrocyte, leucocyte, and platelet counts were reduced. We conclude that this is a model of chronic bone marrow aplasia which has many interesting features of AA. The model is convenient to use and has potential in several areas, particularly for investigations on mechanisms of AA pathogenesis in man.

Anemia, Aplastic↗

[Experimental studies on anti-tumor effects of BLC-modified tumor cell vaccine combined with cisplatin].

BACKGROUND & OBJECTIVE: Chemokines are small molecule proteins that are the main mediators of cell migration. Studies indicated that chemokines could induce antitumor immune response strongly and steadily. At present, there was not antitumor therapy about chemokine BLC combined with chemotherapy. This study was designed to explore the anti-tumor effects and mechanisms of BLC-modified tumor cell vaccine combined with cisplatin. METHODS: Firstly, we transfected pcDNA-BLC into murine tumor cell lines and established stable transfected tumor cell lines (Colon26 and LL/2) to express BLC. Null plasmid pcDNA3.1 (+) was also transfected into Colon 26 or LL/2 cells stably for comparison. We established mouse model with pcDNA-BLC stable transfected tumor cells (Tc), control mouse model with pcDNA3.1(+) stable transfected tumor cells (Pc), and mouse model with parental tumor cells (Nc). Then the 60 mice were inoculated subcutaneously (s.c.) in the right flanks with a total of 5x10(5) viable tumor cells (Tc to 20 mice, Pc to 20 mice, and Nc to 20 mice, respectively; 6-8 week BALB/c female mouse in colon 26 mouse model or 6-8 week C57BL/6 female mouse in LL/2 mouse model). The groups (Tc, Pc, and Nc) were randomly subdivided into Group A and Group B with 10 mice for each, resulting in Tc-A/Tc-B, Pc-A/Pc-B, and Nc-A/Nc-B, respectively. Group A (including Tc-A, Pc-A, and Nc-A) as chemotherapy group was injected (i.p.) with 0.1 ml cisplatin at the concentration of 2 mg/kg once a week for two weeks; Group B (including Tc-B, Pc-B, and Nc-B) as control with 0.1 normal saline. We further observed anti-tumor activity including the tumor growth, mice survival rate, side effects as well as tumor morphological analysis. Apoptotic cells were also determined in tumor tissues. RESULTS: The combination therapy group Tc-A showed significant anticancer activities. The tumor growth was inhibited efficiently with 3/10 mice showing complete regression in LL/2 mouse model and 1/10 mice showing complete regression in Colon 26 mouse model. The combination therapy group Tc-A showed that the survival rate of mice was 100% in the two mouse models, compared with 68% in group Tc-B in C57BL/6 mouse model and 65% in group Tc-B in Colon 26 mouse model and those in other groups. In addition, the combination therapy group Tc-A induced tumor cell apoptosis significantly. CONCLUSIONS: The therapy of BLC-modified tumor cell vaccine combined with cisplatin had significant synergistic effect against tumor. It might develop a new approach for specific immunotherapy of tumors.

Animals↗

Assessment of the role of antibiotics and enterococcal virulence factors in a mouse model of extraintestinal translocation.

OBJECTIVE: To study the relative contribution of antibiotics and bacterial virulence factors in the process of translocation of Enterococcus faecalis from the gut to extraintestinal organs. DESIGN: Prospective controlled animal study. SETTING: Animal experimental laboratory at a university medical center. SUBJECTS: Fifty-two female Balb/c mice. INTERVENTIONS: We developed a mouse model to study the translocation of Enterococcus faecalis from the intestinal tract. Balb/c mice received sterile drinking water or antibiotic combinations to deplete their indigenous intestinal microflora. The animals subsequently were fed genetically engineered enterococci expressing different combinations of the putative enterococcal virulence factors aggregation substance and binding substance. Animals were killed, and their livers, spleens, and mesenteric lymph nodes were aseptically removed and cultured along with fecal samples for enumeration of bacteria. MEASUREMENTS AND MAIN RESULTS: All animals were colonized with the test strains at 2-6 x 109 colony forming units/g of feces; in the antibiotic-treated animals, feces were free from anaerobes and Enterobacteriaceae. In animals fed the identical bacterial mutant, the colony counts in mesenteric lymph nodes were significantly lower in mice not treated with antibiotics than in those treated with antibiotics (p =.016). Multigroup analysis of variance revealed no significant differences of the translocation frequencies for the different mutant strains; however, the differences were statistically significant for all groups receiving antibiotics vs. the group not receiving antibiotics (p <.05-.01). There was a trend (although not statistically significant) for a higher proportion of positive cultures from either spleen or liver in mice that had enterococci recovered from their mesenteric lymph nodes (28%) relative to those that did not have enterococci isolated from the lymph nodes (12%; rate ratio 2.39, p =.30 by logistic regression analysis). CONCLUSIONS: Oral antibiotics can select for extraintestinal translocation of Enterococcus faecalis, and neither aggregation substance nor binding substance seems to be required for this process. The experiments encourage further exploration of host and microbial factors contributing to translocation and may provide a better understanding of the pathogenesis of enterococcal infections in patients in intensive care units.

Animals↗