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PubMed1991

Comparison of the pathogenicity of three species of coagulase-negative Staphylococcus in a mouse model with and without a foreign body.

Staphylococcus schleiferi, Staphylococcus lugdunensis, and Staphylococcus epidermidis produce a high incidence of abscesses in a mouse model with an implanted foreign body. We investigated the significance of the foreign body in this process. Fourteen strains of S. schleiferi, S. epidermidis, and S. lugdunensis were tested in our model. A preadhered foreign body was implanted into one mouse group, followed by injection of a test strain. Another group received injection without implant. Abscesses were assessed at 7 days; foreign bodies and infected tissues were cultured. The percent of samples that developed abscesses or were culture positive was compared for each strain. Nearly all mice infected with S. schleiferi developed abscesses and were culture positive. The foreign body made no difference in abscess formation for three of four S. schleiferi but increased the incidence of both organism recovery and abscess for three of five S. epidermidis. The foreign body enhanced abscess formation for four of five S. lugdunensis, with all five strains yielding significantly more culture recovery. Although the pathogenicity of nine strains was increased by the foreign body, five strains yielded high abscess and culture recovery rates that were not enhanced by its presence.

Abscess↗
PubMed1990

New mouse models for chronic Cryptosporidium infection in immunodeficient hosts.

Cryptosporidium sp. causes fulminant diarrhea and chronic infection in immunocompromised, particularly human immunodeficiency virus-infected, persons. The lack of in vitro cultivation and a suitable animal model has limited development of effective treatment. We describe two new mouse models of chronic symptomatic cryptosporidiosis in adult athymic mice and in T-cell subset-depleted mice. A progressive infection, fatal within 4 months, occurred in most adult athymic mice; a few developed stable infections. Symptoms included dehydration, weight loss, intermittent diarrhea, and jaundice. Pathologic abnormalities and organisms localized in the intestine in stable infections but involved the hepatobiliary tree and pancreas in others. Lymphoid cells from histocompatible, Cryptosporidium sp.-immune mice cured infected nude mice. Identical infections occurred in neonatally infected BALB/c mice treated with anti-CD4 monoclonal antibodies alone or also with anti-CD8 monoclonal antibodies; the mice were cured when the monoclonal antibody treatments were stopped. These models will be useful in definition of the immune defects that permit chronic cryptosporidiosis to develop and in assessment of treatment modalities.

Animals↗
PubMed1986

A 66-base pair insert bridges the deletion responsible for a mouse model of beta-thalassemia.

The breakpoints of the deletion responsible for the Hbb(th-1) mouse model of beta-thalassemia have been isolated. A 3709 (+/- 2)-base pair (bp) region, including the entire beta major globin gene and 2 kilobases of 5' flanking region, is deleted. A novel 66 (+/- 2)-bp sequence, ending in a stretch of 25 dA:dT base pairs, was found to bridge the deletion. A region of the normal murine genome, containing the first 43 bp of the deletion-associated insert (DAI), but lacking the 25-bp dA:dT sequence, was isolated. All normal mice tested contain this DAI-like element and several inbred strains contain an additional DAI-like element. The sequence spanning the Hbb(th-1) deletion may be a reverse transcript of this region.

Animals↗
PubMed1984

Gastric emptying and small intestinal transit in the piebald mouse model for Hirschsprung's disease.

Gastric emptying and small intestinal transit were investigated in the piebald mouse model for Hirschsprung's disease. These mice exhibited aganglionosis of the terminal segment of the large intestine. This condition was accompanied by fecal stasis and megacolon. Gastric emptying of saline or milk meals was slower in the mice with aganglionic or induced megacolon than in the normal mice, but the rate of emptying was faster than after administration of morphine (10 mg/kg). In the small intestine, the distribution of the radiolabeled marker and the advancing edge of the marker profile were abnormal in the mice with megacolon. There were small differences between the megacolonic and normal mice in the distance traversed by the advancing edge of the intraluminal profile of the marker. These results are evidence for disturbances of gastric and small intestinal motor function that occur in mice secondary to development of megacolon.

Animals↗
PubMed1982

A quantitative analysis of leptomeric fibrils in an adriamycin/carnitine chronic mouse model.

A quantitative ultrastructural analysis of leptomeres in cardiac muscle was performed using an adriamycin/carnitine chronic mouse model. Five animals from each of the following four groups were sacrificed for evaluation by electron microscopy: the control group received saline injections only; the carnitine group received carnitine orally; the adriamycin group received a chronic dose of adriamycin (10 mg/kg over 4 weeks); the adriamycin/carnitine group received both the adriamycin and carnitine dosage regimens. The leptomeres were quantitated using a double-blind method. The total number of leptomeres were scored for 20 random low-power electron micrographs from each of 5 animals within each group. The adriamycin group contained 3 of the 4 lowest leptomere scores. The relationships between myofibrillar disruption (MD) and the number of leptomeres found in an intramyofibrillar location(IML) were then determined for each of the four groups using linear regression analysis. In the control group, increased MD was associated with a decrease in the number of IML. In the carnitine group, increased MD was associated with an increase in IML. In the adriamycin group, no significant change in the number of IML occurred with increasing levels of MD. The adriamycin/carnitine group was similar to the control group. It was concluded from this study that 1) a relationship exists between MD and the number of IML in normal murine cardiac muscle; 2) carnitine produces an inverse effect on this normal relationship; 3) adriamycin disturbs the normal relationship between IML and MD; and 4) the administration of carnitine to adriamycin-treated animals restored the normal relationship. The physiological significance of the leptomere to the cardiac cell is then discussed.

Animals↗
PubMed1985

Glycemic modulation of tumor tolerance in a mouse model of breast cancer.

Marked sensitivity of tumor tolerance to blood glucose level is demonstrated in a mouse model of human breast cancer. A theory is cited that explains the high association of hyperglycemia with malignancy, especially breast cancer, via glycemic modulation of cellular immunity. Three groups of BALB/C mice were injected with an aggressive mammary tumor and placed on three dietary regimens designed to produce three different glycemic levels. Mortalities 70 days after injection were 16 of 24 hyperglycemic mice, 8 of 24 normoglycemic, and 1 of 20 hypoglycemic (chi-square p less than .005). Taken together with other experiments and human data discussed briefly, this result suggests that glycemic modulation of tumor tolerance should be evaluated in human trials.

Animals↗
PubMed1976

Hypophosphatemia: mouse model for human familial hypophosphatemic (vitamin D-resistant) rickets.

A new dominant mutation in the laboratory mouse, hypophosphatemia (gene symbol Hyp), has been identified. The Hyp gene is located on the X-chromosome and maps at the distal end. Mutant mice are characterized by hypophosphatemia, bone changes resembling rickets, diminished bone ash, dwarfism, and high fractional excretion of phosphate anion (low net tubular reabsorption). Phosphate supplementation of the diet from wearning prevents the appearance of severe skeletal abnormalities. The hypophosphatemic male mouse resembles human males with X-linked hypophosphatemia and the Hyp gene is presemably homologous with the X-linked human gene. The mouse model should facilitate study of the defect in transport of plasma inorganic phosphate anion.

Animals↗
PubMed1987

Antitumor activity of intraperitoneal immunotoxins in a nude mouse model of human malignant mesothelioma.

Immunotoxins directed against human transferrin receptor have been evaluated in a nude mouse model of human malignant mesothelioma. Immunotoxins were constructed by linking ricin A chain to murine monoclonal antibodies reactive with the human transferrin receptor. A chain was obtained either by isolation from the parent toxin or by recombinant DNA techniques. These immunotoxins acted as potent in vitro cytotoxins against human malignant mesothelioma cells (H-MESO-1) (ID50, 2 X 10(-9) M). Cytotoxic potency and kinetics of cell kill were potentiated in vitro by the carboxylic ionophore monensin. For in vivo trials, nude mice were injected i.p. with 6-9 X 10(6) human malignant mesothelioma cells 24 h prior to the start of i.p. immunotoxin treatments. The survival of tumor-bearing mice was extended by 149-404%, representing a probable cell kill of 2-4 logs. Specificity of this antitransferrin receptor immunotoxin response was confirmed by the ineffectiveness of irrelevant control immunotoxins and blockade of specific immunotoxin action by excess free antibody. Monensin showed limited in vivo potentiation of immunotoxin effect, but a derivative formed by esterification of monensin with linoleic acid gave improved survival times over treatment with immunotoxin alone. Immunotoxins constructed with ricin A chain have significant tumoricidal activity in this model of regional antitumor therapy. These results may have direct relevance for treatment of i.p. malignancy in clinical settings.

Animals↗
PubMed1989

[Investigations on the etiology of sepsis by using experimental mouse model with leukocytopenia. 1. Influence of antibiotics].

Investigation on the etiology of septicemia occurring among the immunocompromised patients was performed by using experimental model of the mouse with leukocytopenia. The ddY conventional mice of 4 weeks of age were inoculated with cyclophosphamide (CPM) intraperitoneally 3 to 5 times every other day with a dose of 3 mg/mouse once to make an agranulocytic status. Then, intraperitoneal administrations of various antibiotic regimens consisting of ampicillin (ABPC) alone, ABPC + ceftazidime (CAZ), ABPC + CAZ + cloxacillin (MCIPC), ABPC + CAZ + MCIPC + minocycline (MINO) and saline as a control to these immunosuppressed mice were begun once every day for 10 days after the second inoculation of CPM. The mortality rate of the mice given saline as a control was very high with a frequency of 43.3% and there were significant differences between the saline group and another antibiotic groups other than ABPC (p less than 0.01). On the other hand, the mortality rate of the group given APBC showed the highest rate of 70% and it was significantly higher than that of the saline control group (p less than 0.05). The main cause of most of the dead mice was septicemia due to P. aeruginosa and which were isolated from the feces of all these mice and serotype of the strains isolated from the heart blood and feces in the same host corresponded to each other. Moreover, intestinal bacterial flora in mice treated by saline and ABPC which highly showed Pseudomonas sepsis, was occupied dominantly by P. aeruginosa, although P. aeruginosa was not detectable from the experimental environments.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Echinococcus granulosus: use of an intermediate host mouse model to evaluate sources of protective antigens and a role for antibody in the immune response.

A Balb/cJ mouse model was used to determine which stage of the E. granulosus life cycle possessed the most potent protective antigens. Mice were immunized with crude extracts of protoscoleces, brood capsules, cyst fluid, adult worm tissue, eggs or oncospheres and then challenged intraperitoneally with 600 activated oncospheres. Sonically disrupted oncospheres induced the highest levels of protection (greater than 90%) at doses greater than or equal to 10(3) oncosphere equivalents per mouse. High levels of protection were maintained when these preparations were solubilized in SDS. Immunization with Taenia ovis or T. hydatigena oncosphere preparations induced a maximum of 62 and 40% cross-protection, respectively. In passive transfer experiments, serum from triple-infected immune donors that were completely resistant to subsequent challenge induced 69% protection in naive recipients (P less than 0.01). Serum from mice that had been immunized with oncosphere sonicates that were shown to be highly immune, failed to induce statistically significant protection in recipients. A sheep trial confirmed the protective ability of prior infections. Immunization of sheep with a SDS solubilized oncosphere preparation produced 91% protection (P less than 0.01).

Animals↗
PubMed1991

Tumor necrosis factor plays an essential role in determining hypersensitivity pneumonitis in a mouse model.

We examined the importance of the cytokine tumor necrosis factor-alpha (TNF-alpha) in a mouse model of hypersensitivity pneumonitis (HP). Mice of the C57BL/6 strain were instilled intranasally 3 days/wk for 3 wk with 150 micrograms of the actinomycete Faenia rectivirgula (Micropolyspora faeni) to induce HP as a model of farmer's lung. This experimental model was associated with a progressive inflammation in the lungs of challenged mice, seen histologically as cellular infiltrates of large quantities of macrophages and lymphocytes and some neutrophils. The disease in challenged mice treated with a control rabbit serum was also associated with a substantial release of tumor TNF-alpha (up to 80 U/ml of TNF-alpha in the bronchoalveolar lavage [BAL] at 3 wk after beginning of treatment) and interleukin-1, which peaked at 1 wk (approximately 300 U/ml) and diminished thereafter. A very large increase in BAL cell number (11-fold increase versus saline controls) and an enhanced release potential for TNF-alpha by alveolar macrophages was also seen. Lung fibrosis was also evident in challenged animals, as demonstrated by a 2-fold increase in hydroxyproline levels. Infusion of challenged mice with a rabbit polyclonal antibody against TNF-alpha (2 mg/wk) completely abrogated the disease, as mice so treated had normal lung histology. Anti-TNF-alpha blocked cellular recruitment in the lungs (only a 2-fold increase at week 3); it also completely abolished TNF-alpha secretion in the BAL and drastically reduced interleukin-1 levels in this fluid. Anti-TNF-alpha also abolished lung index increases and lung fibrosis, with both parameters similar to that of saline-instilled mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Alveolitis, Extrinsic Allergic↗
PubMedDate not supplied

The effect of liposomal cefoperazone against Pseudomonas aeruginosa in a granulocytopenic mouse model of acute lung infection.

The therapeutic efficacy of liposomal cefoperazone against Pseudomonas aeruginosa was investigated in a granulocytopenic mouse model of acute lung infection. Granulocytopenia was induced in mice by intraperitoneal (i.p.) injection of 200 mg/kg cyclophosphamide. Mice were challenged by exposure to an aerosol containing P. aeruginosa and were treated i.p. with liposomal cefoperazone prepared by the dehydration-rehydration method. The half-life of free cefoperazone in the lungs following i.p. administration of the liposomal drug was significantly lengthened (13 min vs. 261 min), and the cefoperazone activity in the lungs remained above the MIC longer after administration of liposomal cefoperazone than after treatment with cefoperazone. Liposomal cefoperazone was more effective than cefoperazone alone in preventing death of granulocytopenic mice from lethal pulmonary challenge with P. aeruginosa (75% vs. 38% survival, p = 0.031). Finally, P. aeruginosa was cleared faster from the lungs of mice treated with liposomal cefoperazone when compared with those treated with cefoperazone. This study shows that incorporation of cefoperazone into liposomes enhances the activity of the antibiotic against P. aeruginosa in a granulocytopenic host.

Acute Disease↗
PubMed1983

A therapeutic trial of gangliosides and thymosin in the Wobbler mouse model of motor neuron disease.

Mixed bovine gangliosides have been reported to enhance neuronal regeneration and sprouting. The Wobbler mouse model of motor neuron disease was used to test the clinical effects of long-term ganglioside administration on the course of the disease. Mixed gangliosides were injected subcutaneously into a group of 5 Wobbler mice and compared to a control group of 5 Wobbler mice which received saline. Because of several reports implicating involvement of the immune system in ALS, a 3rd group of 5 Wobbler mice received thymosin. All mice were 4 weeks old at commencement of injections. The 3 groups were examined weekly and graded with respect to front leg power, ability to climb a vertical grating, and walking posture. After 4 months of treatment, no significant difference between either experimental group and the controls was found.

Animals↗
PubMed1979

Ultrastructural observations on giardiasis in a mouse model. II. Endosymbiosis and organelle distribution in Giardia muris and Giardia lamblia.

Ultrastructural observations of Giardia muris in a mouse model revealed endosymbiotic microbes not previously reported in Giardia. Endosymbionts 240--360 nm wide, 600--1,400 nm long, and with an internal structure similar to that of bacilli were not seen entering Giardia but were found and appeared to divide within Giardia. No evidence was found of digestion of the endosymbionts by the giardia host in either the trophozoite or the cyst form. Endosymbionts were concentrated centrally around the nuclear area and were uncommon in peripheral feeding regions. The same cellular organelles seen in G. muris were found in Giardia lamblia from human jejunal biopsy material, but no endosymbionts were identified in G. lamblia trophozoites from the seven patients examined. Endosymbionts within Giardia may be found to alter trophozoite pathogenicity, metabolism, range of infectivity, antigenic surface characteristics, and host specificity, as they do in other protozoa.

Animals↗
PubMed1992

Activity and local delivery of azithromycin in a mouse model of Haemophilus influenzae lung infection.

We compared the activities of azithromycin and erythromycin against Haemophilus influenzae in a mouse model of nonparenchymatous lower respiratory tract infection. In vitro and in vivo efficacy data for both drugs were analyzed relative to their pharmacokinetics in lungs and in vivo uptake by phagocytes. Aged C57BL/6 mice (mean age, 15.1 +/- 1.9 months) were infected intratracheally with 10(8) CFU of H. influenzae serotype b. Oral drug administration was initiated 4 h after infection by various dosage regimens. In terms of bacterial killing in the lung, azithromycin was much more active than erythromycin (P less than 0.01). Its in vivo activity was also more durable after a single administration relative to the durability of three doses of erythromycin given at 6-h intervals. The MIC of azithromycin was eightfold lower than that of erythromycin, and better penetration and a longer half-life in lung tissue were achieved after a single oral administration. Phagocytes delivered increased amounts of both drugs to the infected lungs, particularly at the site of infection (bronchoalveolar airspaces), and detectable levels of azithromycin were maintained locally for long periods. The fact that the efficacy of azithromycin coincided with the arrival of large numbers of polymorphonuclear leukocytes within the airspaces suggests that active extracellular concentrations were provided by the release of azithromycin from these cells. This further supports the potential value of once-daily azithromycin regimens for the treatment of lower respiratory tract infections in humans, provided that inhibitory concentrations against common pathogens such as H. influenzae are maintained for adequate periods of time.

Administration, Oral↗
PubMed1983

Virulence of different Pseudomonas species in a burned mouse model: tissue colonization by Pseudomonas cepacia.

The virulence of Pseudomonas aeruginosa and other pseudomonads was examined in a burned mouse model. P. aeruginosa M-2 was highly virulent causing 100% mortality by 38 h with an injection of 10(2) CFU by either a subcutaneous or intraperitoneal route. Subcutaneous injection of 10(2) CFU revealed rapid multiplication of the bacteria at the burn wound with 10(8) CFU/g detectable in the burned skin by 28 h postinjection, 10(5) CFU/g of liver, and 10(3) CFU/ml of blood. Non-P. aeruginosa clinical isolates were markedly less virulent; an injection of greater than or equal to 10(7) CFU caused less than or equal to 60% lethality. P. cepacia SMH colonized the burned skin of thermally injured mice, persisting at levels of 10(7) to 10(8) CFU/g of burned skin after an initial injection of 10(5) CFU. P. cepacia persisted in the burn wound for at least 3 weeks. No organ invasion was detectable throughout this period. Studies with an additional clinical isolate of P. cepacia yielded similar results. An injection of a 10(2) CFU dose revealed that the level of persistence is dose dependent. Results suggest that the tenacious persistence of P. cepacia in the burn wound may provide a model for the study of persistent colonization and infection in a compromised host.

Animals↗
PubMed1991

Use of type 1/type 2 chimeric polioviruses to study determinants of poliovirus type 1 neurovirulence in a mouse model.

We previously described the characteristics of a type 1/type 2 (PV-1/PV-2) chimeric poliovirus, v510, which contains the six amino acids specific for PV-2 in the B-C loop of VP1. This virus was found to be mouse-adapted, as PV-2 and in contrast with PV-1. Determinants of host range were studied in detail and are reported here. PV-1/PV-2 chimeras containing partial PV-1----PV-2 substitutions in the B-C loop of VP1 were obtained by making use of a mutagenesis cartridge on PV-1 cDNA. Analysis of mouse neurovirulence of these chimeras, when correlated with the three-dimensional structure of the v510 capsid, revealed that PV-2 residues important for mouse tropism are those which determine the particular conformation of the B-C loop of VP1 in v510. The mutation of the adenine residue at position 480 of the 5' noncoding region into a guanine residue has been shown to be an important determinant of PV-1 attenuation in monkeys. We show that introduction of this mutation in the v510 genome results in a virus which is partially attenuated for mice. This suggests that analysis of genomic determinants important for PV-1 neurovirulence could be carried out in a mouse model by making use of a mouse-adapted PV-1/PV-2 chimera.

Amino Acid Sequence↗