Rat Model Of Infection Research Articles

A novel rat model of catheter-associated urinary tract infection.

The authors aimed to establish a rat model of catheter-associated UTIs using a complete urethral catheter. Bacterial growth in biofilms on urethral catheters was analyzed using standard culture methods to validate this model. A total of 15 rats were divided into the following three groups according to the duration of indwelling catheter placement: a 2-week group (n = 5, group 1), a 4-week group (n = 5, group 2), and a 6-week group (n = 5, group 3). A urethral catheter was inserted with the distal end buried just beneath the urethra, and it was fixed inside of the urethra with a single suture starting at the vagina so that the suture knot was hidden inside of the vagina, preventing the rats from biting it off. A standard culture method was used to analyze bacterial growth in the biofilms. All 15 urethral catheters were intact at the end of the experiment. Pseudomonas aeruginosa, Escherichia coli, Enterococcus spp., Enterococcus faecalis, and Corynebacterium spp. were identified in the biofilms on the urethral catheters. Our rat UTI model consisting of a complete urinary catheter is feasible. Our study may provide fundamental data for future biofilm studies incorporating molecular techniques, and even clinical studies.

An Essential Role for Coagulase in Staphylococcus aureus Biofilm Development Reveals New Therapeutic Possibilities for Device-Related Infections.

High-level resistance to antimicrobial drugs is a major factor in the pathogenesis of chronic Staphylococcus aureus biofilm-associated, medical device-related infections. Antimicrobial susceptibility analysis revealed that biofilms grown for ≤ 24 hours on biomaterials conditioned with human plasma under venous shear in iron-free cell culture medium were significantly more susceptible to antistaphylococcal antibiotics. Biofilms formed under these physiologically relevant conditions were regulated by SaeRS and dependent on coagulase-catalyzed conversion of fibrinogen into fibrin. In contrast, SarA-regulated biofilms formed on uncoated polystyrene in nutrient-rich bacteriological medium were mediated by the previously characterized biofilm factors poly-N-acetyl glucosamine, fibronectin-binding proteins, or autolytic activity and were antibiotic resistant. Coagulase-mediated biofilms exhibited increased antimicrobial resistance over time (>48 hours) but were always susceptible to dispersal by the fibrinolytic enzymes plasmin or nattokinase. Biofilms recovered from infected central venous catheters in a rat model of device-related infection were dispersed by nattokinase, supporting the important role of the biofilm phenotype and identifying a potentially new therapeutic approach with antimicrobials and fibrinolytic drugs, particularly during the early stages of device-related infection.

In vivo anti-salmonella activity of aqueous extract of Euphorbia prostrata Aiton (Euphorbiaceae) and its toxicological evaluation

ABSTRACT Objective To investigate the in vivo anti-salmonella activity and the safety of aqueous extract of Euphorbia prostratra ( E. prostratra ), a plant commonly used in Cameroon by traditional healers. Methods A Salmonella typhimurium -infected rat model was used for the study. The physiological, biochemical and histopathological markers of possible side effects of this extract were studied using standard methods. Results The extract had a significant effect on the number of viable Salmonella typhimurium recovered from faeces, and could stop salmonellosis after 8 and 10 days of treatment for male and female rats, respectively, with non-toxic doses. However, the biochemical and histopathological analyses revealed that at relatively high doses (≥ 73.48 mg/kg for female and ≥ 122.71 mg/kg for male) the extract could induce liver damage, as illustrated by a rise of serum transaminases’ levels and significant inflammation of the parenchyma and portal vein. Side effects were also observed on the kidneys, as shown by both serum and urinary creatinine, and urinary proteins. Conclusions The overall results indicate that the aqueous extract of E. prostrata has the potential to provide an effective treatment for salmonellosis, including typhoid fever. However, it is necessary to extrapolate these results in large animals, in further studies.

Changes of febrile response and placental pathological inflammation in pregnant rats after intrauterine infection in late gestation

Objective To explore the febrile response and placental pathological inflammation of pregnant rats exposed to intrauterine infection in late gestation. Methods Pregnant Sprague–Dawley rats at gestational day 18 were randomly divided into control group and intrauterine–infected group with six rats in each. The intrauterine–infected group was intraperitoneally injected with 350 μg/kg lipopolysaccharide to establish a rat model of intrauterine infection, while the control group was injected with sterile saline of the same dose. Core temperature was measured every 1 h after intraperitoneal injection of lipopolysaccharide or saline for 8 h. At gestational day 19, after anesthesia, the placentas were taken and stained with HE. The expression levels of tumor necrosis factor–α, interleukin–6, and interleukin–1β in the placenta were determined by enzyme linked immunosorbent assay. Student t test was used for statistical analysis. Results (1) There was no temperature difference between the two groups before experimental treatment (P>0.05). Core temperature was increased 1 h after the lipopolysaccharide injection, reaching (37.67±0.08) ℃. The increase of temperature was significant compared with the control group [(37.13±0.08) ℃, t=10.178, P<0.01] . Fever was lowered 2 h later and the rats became hypothermic with body temperature below 37 ℃ in the intrauterine–infected group. The body temperature in the intrauterine–infected group after 2–6 h was (37.70±0.10), (37.23±0.05), (36.57±0.06), (36.60±0.10) and (36.57±0.08) ℃, respectively, compared with the control group [(36.83±0.12), (36.63±0.12), (36.71±0.07), (36.87±0.12), and (36.77±0.08) ℃, respectively], the differences being all statistically significant (t=11.402, 11.163, –4.025, –4.000 and –4.243, all P<0.01). (2) HE staining revealed large amounts of neutrophils infiltration, vascular enlargement and congestion in the placenta of the intrauterine–infected rats. No inflammatory cell infiltration was observed in the control placentas. (3) The expression levels of proinflammatory cytokine tumor necrosis factor–α [(0.62±0.02) ng/g], interleukin–6 [(66.12±5.11) ng/g], and interleukin–1β [(7.09±1.23) ng/g] in the intrauterine–infected group were higher than those in the control group [(0.27±0.01), (16.71±1.55) and (2.86±0.38) ng/g, respectively]. The differences were all statistically significant (t=–26.608, –18.749 and –5.714, all P<0.01). Conclusion After exposure to lipopolysaccharide in late gestation, pregnant rats show significant inflammatory response in the placenta, with suppression of febrile response and presence of hypothermia. Key words: Pregnancy complications, infectious; Fever; Hypothermia; Placenta; Cytokines; Pregnancy trimester, third; Lipopolysaccharides; Disease models, animal

Role of exopolysaccharide in Aggregatibacter actinomycetemcomitans-induced bone resorption in a rat model for periodontal disease.

Aggregatibacter actinomycetemcomitans a causative agent of periodontal disease in humans, forms biofilm on biotic and abiotic surfaces. A. actinomycetemcomitans biofilm is heterogeneous in nature and is composed of proteins, extracellular DNA and exopolysaccharide. To explore the role played by the exopolysaccharide in the colonization and disease progression, we employed genetic reduction approach using our rat model of A. actinomycetemcomitans-induced periodontitis. To this end, a genetically modified strain of A. actinomycetemcomitans lacking the pga operon was compared with the wild-type strain in the rat infection model. The parent and mutant strains were primarily evaluated for bone resorption and disease. Our study showed that colonization, bone resorption/disease and antibody response were all elevated in the wild-type fed rats. The bone resorption/disease caused by the pga mutant strain, lacking the exopolysaccharide, was significantly less (P < 0.05) than the bone resorption/disease caused by the wild-type strain. Further analysis of the expression levels of selected virulence genes through RT-PCR showed that the decrease in colonization, bone resorption and antibody titer in the absence of the exopolysaccharide might be due to attenuated levels of colonization genes, flp-1, apiA and aae in the mutant strain. This study demonstrates that the effect exerted by the exopolysaccharide in A. actinomycetemcomitans-induced bone resorption has hitherto not been recognized and underscores the role played by the exopolysaccharide in A. actinomycetemcomitans-induced disease.

Discovery of an Oral Respiratory Syncytial Virus (RSV) Fusion Inhibitor (GS-5806) and Clinical Proof of Concept in a Human RSV Challenge Study

GS-5806 is a novel, orally bioavailable RSV fusion inhibitor discovered following a lead optimization campaign on a screening hit. The oral absorption properties were optimized by converting to the pyrazolo[1,5-a]-pyrimidine heterocycle, while potency, metabolic, and physicochemical properties were optimized by introducing the para-chloro and aminopyrrolidine groups. A mean EC50 = 0.43 nM was found toward a panel of 75 RSV A and B clinical isolates and dose-dependent antiviral efficacy in the cotton rat model of RSV infection. Oral bioavailability in preclinical species ranged from 46 to 100%, with evidence of efficient penetration into lung tissue. In healthy human volunteers experimentally infected with RSV, a potent antiviral effect was observed with a mean 4.2 log10 reduction in peak viral load and a significant reduction in disease severity compared to placebo. In conclusion, a potent, once daily, oral RSV fusion inhibitor with the potential to treat RSV infection in infants and adults is reported.

Rift Valley fever virus infection in golden Syrian hamsters.

Rift Valley fever virus (RVFV) is a formidable pathogen that causes severe disease and abortion in a variety of livestock species and a range of disease in humans that includes hemorrhagic fever, fulminant hepatitis, encephalitis and blindness. The natural transmission cycle involves mosquito vectors, but exposure can also occur through contact with infected fluids and tissues. The lack of approved antiviral therapies and vaccines for human use underlies the importance of small animal models for proof-of-concept efficacy studies. Several mouse and rat models of RVFV infection have been well characterized and provide useful systems for the study of certain aspects of pathogenesis, as well as antiviral drug and vaccine development. However, certain host-directed therapeutics may not act on mouse or rat pathways. Here, we describe the natural history of disease in golden Syrian hamsters challenged subcutaneously with the pathogenic ZH501 strain of RVFV. Peracute disease resulted in rapid lethality within 2 to 3 days of RVFV challenge. High titer viremia and substantial viral loads were observed in most tissues examined; however, histopathology and immunostaining for RVFV antigen were largely restricted to the liver. Acute hepatocellular necrosis associated with a strong presence of viral antigen in the hepatocytes indicates that fulminant hepatitis is the likely cause of mortality. Further studies to assess the susceptibility and disease progression following respiratory route exposure are warranted. The use of the hamsters to model RVFV infection is suitable for early stage antiviral drug and vaccine development studies.

Impaired spatial learning and memory skill in Sprauge-Dawley rat model of congenital human cytomegalovirus infection

Objective To investigate the influence of congenital human cytomegalovirus (HCMV) infection on spatial learning and memory skill in rats and its mechanism. Methods Forty specific pathogen free Sprague-Dawley rats (12 weeks old, male and female mated by 1∶3) were selected and randomly divided into the experimental group and control group, fifteen in each group. Fertilized female rats in the experimental group were injected with 0.5 ml HCMV (1×10-6 of the 50% tissue culture infective dose/rat) by intraperitoneal inoculation on the third gestational day. At the same time, a 0.5 ml suspension of human embryonic lung fibroblast cells was inoculated intraperitoneally into fertilized female rats in the control group. HCMV-specific IgM and IgG in maternal peripheral blood of the two groups were detected on one week after inoculation. Both side of hippocampus of ten neonatal rats (five in each group), born by cesarean section, were collected for virus isolation. Spatial learning and memory skill in 4-6 week offspring in the two groups were assessed using the Morris Water Maze (MWM) test, and results were presented by Origin 8.0. Pathological damage in offspring was determined by microscopy and electron microscopy. Independent samples t-test, Chi-square and rank sum tests were used for statistical analysis. Results (1) Compared with the control group, litter size and mortality of neonatal rats within one week after birth in the experimental group were significantly higher [litter size: (8.7±3.1) vs (5.5±2.4), t=2.366, P=0.033; mortality of neonatal rats: 4.9% (6/122) vs 26.1% (18/69), χ2=191.020, P=0.000. In the MWM test, escape latency in 30-day old offspring in the experimental group was significantly increased compared with the control group during 4 days of training (F=499.473, P=0.000). The total distance in the experimental group was significantly increased compared with the control group (F=440.167, P=0.000). In addition, the numbers of platform crossing (4.21±1.44) and swimming time in the target quadrant [(26±4)%] in the congenital infection group were decreased compared with the control group [(7.50±1.72) and (47±5)%, t=7.182 and 15.487, P=0.003 and 0.000]. In the congenital infection group, liquefaction necrosis of the cerebral cortex (light microscopy) and myelin disintegration in the hippocampus (electron microscopy) were observed. Conclusions Injury of the cortex and hippocampus in offspring with congenital HCMV infection is involved in the pathological mechanism of decreased spatial learning and memory skill. Key words: Pregnancy complications, infectious; Cytomegalovirus infections; Hippocampus; Learning; Memory; Disease models, animal

Inhibition of Quorum Sensing-Controlled Virulence Factors and Biofilm Formation in Pseudomonas aeruginosa by Culture Extract from Novel Bacterial Species of Paenibacillus Using a Rat Model of Chronic Lung Infection.

Quorum sensing (QS) is a key regulator of virulence factors and biofilm formation in Gram-negative bacteria such as Pseudomonas aeruginosa. Microorganisms that inhabit soil are of strategic importance in the discovery of compounds with anti-QS properties. The objective of the study was to test the culture extract of a taxonomically novel species of Paenibacillus strain 139SI for its inhibitory effects on the QS-controlled virulence factors and biofilm formation of Pseudomonas aeruginosa both in vitro and in vivo. The Paenibacillus sp. culture extract was used to test its anti-QS effects on the LasA protease, LasB elastase, pyoverdin production, and biofilm formation of P. aeruginosa as well as evaluate its therapeutic effects on lung bacteriology, pathology, hematological profile, and serum antibody responses of experimental animals in a rat model of chronic lung infection. Results showed significant decrease in the activities of QS-controlled LasA protease, LasB elastase pyoverdin, and biofilm formation of P. aeruginosa caused by the culture extract. Moreover, the extract significantly prolonged the survival times of rats and facilitated the clearance of biofilm infections from infected lungs. In conclusion, the antiquorum sensing effects of culture extract from a novel species of Paenibacillus provide new insights to combat biofilm-associated infections.

Essential genes in the infection model of Pseudomonas aeruginosa-PCR-based signature-tagged mutagenesis.

PCR-based signature tagged mutagenesis is an "en masse" screening technique based upon unique oligonucleotide tags (molecular barcodes) for identification of genes that will diminish or enhance maintenance of an organism in a specific ecological niche or environment. PCR-based STM applied to Pseudomonas aeruginosa permitted the identification of genes essential for in vivo maintenance by transposon insertion and negative selection in a mixed population of bacterial mutants. The innovative adaptations and refinement of the technology presented here with P. aeruginosa STM mutants selected in the rat model of chronic lung infection have given critical information about genes essential for causing a chronic infection and a wealth of information about biological processes in vivo. The additional use of competitive index analysis for measurement of the level of virulence in vivo, microarray-based screening of selected prioritized STM mutants coupled to metabolomics analysis can now be attempted systematically on a genomic scale. PCR-based STM and combined whole-genome methods can also be applied to any organism having selectable phenotypes for screening.

Lytic activity by temperate phages of Pseudomonas aeruginosa in long-term cystic fibrosis chronic lung infections.

Pseudomonas aeruginosa is the most common bacterial pathogen infecting the lungs of cystic fibrosis (CF) patients. The transmissible Liverpool epidemic strain (LES) harbours multiple inducible prophages (LESϕ2; LESϕ3; LESϕ4; LESϕ5; and LESϕ6), some of which are known to confer a competitive advantage in an in vivo rat model of chronic lung infection. We used quantitative PCR (Q-PCR) to measure the density and dynamics of all five LES phages in the sputa of 10 LES-infected CF patients over a period of 2 years. In all patients, the densities of free-LES phages were positively correlated with the densities of P. aeruginosa, and total free-phage densities consistently exceeded bacterial host densities 10–100-fold. Further, we observed a negative correlation between the phage-to-bacterium ratio and bacterial density, suggesting a role for lysis by temperate phages in regulation of the bacterial population densities. In 9/10 patients, LESϕ2 and LESϕ4 were the most abundant free phages, which reflects the differential in vitro induction properties of the phages. These data indicate that temperate phages of P. aeruginosa retain lytic activity after prolonged periods of chronic infection in the CF lung, and suggest that temperate phage lysis may contribute to regulation of P. aeruginosa density in vivo.

Autoimmunity Links Vinculin to the Pathophysiology of Chronic Functional Bowel Changes Following Campylobacter jejuni Infection in a Rat Model.

Acute gastroenteritis can precipitate irritable bowel syndrome (IBS) in humans. Cytolethal distending toxin is common to all pathogens causing gastroenteritis. Its active subunit, CdtB, is associated with post-infectious bowel changes in a rat model of Campylobacter jejuni infection, including small intestinal bacterial overgrowth (SIBO). To evaluate the role of host antibodies to CdtB in contributing to post-infectious functional sequelae in this rat model. Ileal tissues from non-IBS human subjects, C. jejuni-infected and control rats were immunostained with antibodies to CdtB, c-Kit, S-100, PGP 9.5 and vinculin. Cytosolic and membrane proteins from mouse enteric neuronal cell lysates were immunoprecipitated with anti-CdtB and analyzed by mass spectrometry. ELISAs were performed on rat cardiac serum using CdtB or vinculin as antigens. Anti-CdtB antibodies bound to a cytosolic protein in interstitial cells of Cajal (ICC) and myenteric ganglia in C. jejuni-infected and naïve rats and human subjects. Mass spectrometry identified vinculin, confirmed by co-localization and ELISAs. Anti-CdtB antibodies were higher in C. jejuni-infected rats (1.27 ± 0.15) than controls (1.76 ± 0.12) (P < 0.05), and rats that developed SIBO (2.01 ± 0.18) vs. rats that did not (1.44 ± 0.11) (P = 0.019). Vinculin expression levels were reduced in C. jejuni-infected rats (0.058 ± 0.053) versus controls (0.087 ± 0.023) (P = 0.0001), with greater reductions in rats with two C. jejuni infections (P = 0.0001) and rats that developed SIBO (P = 0.001). Host anti-CdtB antibodies cross-react with vinculin in ICC and myenteric ganglia, required for normal gut motility. Circulating antibody levels and loss of vinculin expression correlate with number of C. jejuni exposures and SIBO, suggesting that effects on vinculin are important in the effects of C. jejuni infection on the host gut.

A novel rat model of incisional surgical site infection model developed using absorbable multifilament thread inoculated with Escherichia coli.

The development of an effective rat model of incisional surgical site infection (SSI) has so far proven difficult. In this study, we created a novel incisional SSI model and validated it in terms of both macroscopic and microscopic aspects including its response to treatment using antimicrobial wound-dressing, Aquacel Ag(®). Wounds were created on the dorsum of rats. 3-0 Vicryl(®) threads inoculated with Escherichia coli were inserted in the wound beds in the infection group (n = 6). The wounds were closed for two days to induce infection and then opened and covered with polypropylene sheets during the study. Aquacel Ag was placed under the polypropylene sheet in the infected wounds of the Aquacel Ag group rats (n = 6). The wounds in the control group (n = 6) contained sterile Vicryl thread that had not been inoculated with E. coli. The macroscopic appearance, wound area, bacterial counts, and histology of each group were evaluated. The infection group demonstrated significantly lower wound healing (p < 0.001), greater bacterial counts (median [interquartile range] ratings, 2.15 × 10(7) [0.51 × 10(7)-53.40 × 10(7)] vs 2.07 × 10(4) [0.60 × 10(4)-4.45 × 10(4)] CFU/g, respectively; p < 0.01), and severer histological inflammation (p < 0.001) than the control group. The Aquacel Ag group was only able to show significantly better wound healing than the infection group (p < 0.001). The new incisional SSI model exhibited all clinical manifestations of incisional SSI. It could be utilized to assess the effectiveness of newly developed treatments for incisional SSI.

D-optimal experimental approach for designing topical microemulsion of itraconazole: Characterization and evaluation of antifungal efficacy against a standardized Tinea pedis infection model in Wistar rats

The study aims to statistically develop a microemulsion system of an antifungal agent, itraconazole for overcoming the shortcomings and adverse effects of currently used therapies. Following preformulation studies like solubility determination, component selection and pseudoternary phase diagram construction, a 3-factor D-optimal mixture design was used for optimizing a microemulsion having desirable formulation characteristics. The factors studied for sixteen experimental trials were percent contents (w/w) of water, oil and surfactant, whereas the responses investigated were globule size, transmittance, drug skin retention and drug skin permeation in 6h. Optimized microemulsion (OPT-ME) was incorporated in Carbopol based hydrogel to improve topical applicability. Physical characterization of the formulations was performed using particle size analysis, transmission electron microscopy, texture analysis and rheology behavior. Ex vivo studies carried out in Wistar rat skin depicted that the optimized formulation enhanced drug skin retention and permeation in 6h in comparison to conventional cream and Capmul 908P oil solution of itraconazole. The in vivo evaluation of optimized formulation was performed using a standardized Tinea pedis model in Wistar rats and the results of the pharmacodynamic study, obtained in terms of physical manifestations, fungal-burden score, histopathological profiles and oxidative stress. Rapid remission of Tinea pedis from rats treated with OPT-ME formulation was observed in comparison to commercially available therapies (ketoconazole cream and oral itraconazole solution), thereby indicating the superiority of microemulsion hydrogel formulation over conventional approaches for treating superficial fungal infections. The formulation was stable for a period of twelve months under refrigeration and ambient temperature conditions. All results, therefore, suggest that the OPT-ME can prove to be a promising and rapid alternative to conventional antifungal therapies against superficial fungal infections.

Pharmacokinetics and dose response of three different anti-TB drugs in rat (balb/c) infection model of tuberculosis

IntroductionRobust and physiologically relevant infection models are required to investigate pharmacokinetic–pharmacodynamic (PK/PD) correlations for anti-tuberculosis agents at preclinical discovery. Material and methodsThis study has validated an inhalation-based rat infection model of tuberculosis (TB) harboring mycobacteria in a replicating state that is suitable for investigating pharmacokinetics and drug action of anti-tubercular agents. A reproducible and actively replicating lung infection was established in Wistar rats by inhalation of a series of graded inocula of Mycobacterium tuberculosis (MTB). Following an initial instillation of ∼20(10)log10CFU/lung, MTB grew logarithmically for the first 3weeks, and then entered into a chronic phase with no net increase in pulmonary bacterial loads. Dose response of front-line anti-TB drugs was investigated following pharmacokinetic measurements in the plasma of infected rats. ResultsRifampicin, Isoniazid, and pyrazinamide dosed per orally exhibited bactericidality and good dose response with maximal effect of 6.77, 3.55, and 5.901.92log10CFU reductions in the lungs, respectively. In contrast, ethambutol was merely bacteriostatic with 5.90log10CFU/lung reduction and did not reduce the bacterial burden beyond the initial bacterial loads present at the beginning of treatment in spite of high blood ethambutol levels. Rat infection model with actively replicating bacilli provides a physiologically distinct and pharmacologically relevant model that can be exploited to distinguish investigational compounds into bacteriostatic or bactericidal scaffolds. ConclusionsThe present study proposes that this rat infection model – although it needs more drug substance – can be used in early discovery settings to investigate the pharmacology of novel anti-tubercular agents for the treatment of active pulmonary tuberculosis.

The attenuated virulence of a Burkholderia cenocepacia paaABCDE mutant is due to inhibition of quorum sensing by release of phenylacetic acid.

The phenylacetic acid degradation pathway of Burkholderia cenocepacia is active during cystic fibrosis-like conditions and is necessary for full pathogenicity of B. cenocepacia in nematode and rat infection models; however, the reasons for such requirements are unknown. Here, we show that the attenuated virulence of a phenylacetic acid catabolism mutant is due to quorum sensing inhibition. Unlike wild-type B. cenocepacia, a deletion mutant of the phenylacetyl-CoA monooxygenase complex (ΔpaaABCDE) released phenylacetic acid in the medium that favours infection in Caenorhabditis elegans. Addition of phenylacetic acid further decreased the pathogenicity of the ΔpaaABCDE, which cannot metabolize phenylacetic acid, but did not affect the wild-type, due to phenylacetic acid consumption. In line with reduced detection of acyl-homoserine lactones in spent medium, the ΔpaaABCDE exhibited transcriptional inhibition of the quorum sensing system cepIR. Phenotypes repressed in ΔpaaABCDE, protease activity and pathogenicity against C. elegans, increased with exogenous N-octanoyl-L-homoserine lactone. Thus, we demonstrate that the attenuated phenotype of B. cenocepacia ΔpaaABCDE is due to quorum sensing inhibition by release of phenylacetic acid, affecting N-octanoyl-L-homoserine lactone signalling. Further, we propose that active degradation of phenylacetic acid by B. cenocepacia during growth in cystic fibrosis-like conditions prevents accumulation of a quorum sensing inhibiting compound.

A rat model of pulmonary infection after cardiac transplant.

Cardiac allograft rejection and infection are leading causes of morbidity and mortality after transplant. The lack of an animal model has hindered related research. We have developed a rat model of pulmonary infection after cardiac transplant to address this issue. Lewis rats received Wistar rat heart allografts, cardiac rejection was induced by cessation of cyclosporine injection, and pulmonary infection was induced by Pseudomonas aeruginosa intrabronchial inoculation. Development of pulmonary infection and/or heart rejection was assessed by histopathology. Histopathologic findings showed that a dose of 2 × 108 colony forming units of Pseudomonas aeruginosa intrabronchial inoculation is sufficient to cause severe pneumonia without being lethal to transplanted animals. Daily administration of 10 mg/kg of cyclosporine reliably suppressed rejection, and withdrawal for 7 days can obtain a consistent International Society for Heart and Lung Transplantation 3R rejection. The current study represents a simple and effective rat model of pulmonary infection along, or in combination, with rejection after heart transplant, which can be used for research of infection-rejection in cardiac transplant settings.

A novel rat model of intra-uterine infection using lipopolysaccharide: evaluation of placental and neonatal complications

A novel rat model of intra-uterine infection using lipopolysaccharide: evaluation of placental and neonatal complications

Analysis of components of mesenteric lymph in rats with severe intraperitoneal infection

To investigate the components of mesenteric lymph of the rats with severe intraperitoneal infection, and inquire into the effect of intestinal lymphatic pathway in severe intraperitoneal infection. Twenty-four male Wistar rats were randomly divided into two groups according to random number table method, namely model group and sham group with 12 rats in each group. The rat model of severe intraperitoneal infection was reproduced by injecting artificial gastric juice and E.coli intraperitoneally. Mesenteric lymph in both groups was collected 4 hours after the reproduction of the model, and white blood cells were counted and classified. The levels of endotoxin, alkaline phosphatase (AKP), lactate dehydrogenase (LDH), creatine kinase (CK), glutamine transferase (GST), protein and cytokines of mesenteric lymph were determined. Compared with the sham group, there was an increase in the neutrophil ratio in mesenteric lymph (0.167±0.004 vs. 0.610±0.006, t=33.520, P<0.001), however the percentage of both macrophages (0.009±0.001 vs. 0.020±0.004, t=-6.677, P<0.001) and lymphocytes (0.824±0.005 vs. 0.921±0.004, t=-31.471, P<0.001) was decreased in model group. Compared with sham group, the levels of endotoxin (0.346±0.022 kEU/L vs. 0.186±0.001 kEU/L, t=18.103, P<0.001), AKP [U (king unit): 13.97±5.55 vs. 3.76±0.18, t=4.503, P=0.006], LDH (2 827.45±1 940.32 U/L vs. 712.68±14.09 U/L, t=2.670, P=0.044), CK (2.19±1.21 kU/L vs. 0.70±0.01 kU/L, t=3.035, P=0.029), GST (12.33±6.53 kU/L vs. 1.36±0.39 kU/L, t=4.105, P=0.009) were all significantly elevated. The concentration of protein (4.40±0.48 g/L vs. 2.84±0.16 g/L, t=6.882, P=0.001), tumor necrosis factor-α (TNF-α: 499.39±76.36 ng/L vs. 180.90±70.98 ng/L, t=7.483, P<0.001), interleukin-6 (IL-6: 13.74±0.78 μg/L vs. -0.07±0.07 μg/L, t=52.972, P<0.001), intercellular adhesion molecule-1 (ICAM-1: 2 754.19±221.48 ng/L vs. 1 362.85±393.43 ng/L, t=6.891, P<0.001) and monocyte chemo-attractant protein-1 (MCP-1: 28.23±1.77 μg/L vs. 24.87±1.15 μg/L, t=3.561, P=0.007) and high mobility group protein-1 (HMGB-1: 1 392.78±572.42 ng/L vs. 564.17±21.32 ng/L, t=3.543, P=0.016) in mesenteric lymph in model group were significantly higher than those in sham group. Intestinal lymphatic pathway maybe the early pathway for the production of remote organ injury caused by severe intraperitoneal infection.

Evaluation of ceftiofur&amp;ndash;PHBV microparticles in rats

Despite the high number of antibiotics used for the treatment of infectious disease in animals, the development of slow release formulations presents a significant challenge, particularly in using novel biomaterials with low cost. In this report, we studied the pharmacokinetics, toxicity, and therapeutic activity of ceftiofur–PHBV (ceftiofur–poly(3-hydroxybutyrate-co-3-hydroxyvalerate)) in rats. The pharmacokinetic study demonstrated a sustained release of ceftiofur into the bloodstream, with detectable levels over the minimum inhibitory concentration for at least 17 days after a single intramuscular injection of ceftiofur–PHBV (10 mg/kg weight). In addition, the toxicological evaluation of biochemical, hematological, and coagulation blood parameters at the therapeutic dose demonstrated the safety of ceftiofur–PHBV, with no adverse effects. In addition, ceftiofur–PHBV exhibited a therapeutic effect for a longer time period than the nonencapsulated ceftiofur in rats challenged with Salmonella Typhimurium. The slow release of ceftiofur from the ceftiofur–PHBV, its low toxicity in the blood parameters evaluated, and the efficacy in the rats infected with Salmonella Typhimurium make ceftiofur–PHBV a strong candidate for biotechnological applications in the veterinary industry.