Induction of Experimental Peri-Implantitis with Strains Selected from the Human Oral Microbiome.

Peri-implantitis (PI), the most widespread condition in the oral cavity, affects patients globally; thus, advanced research in both in vitro and in vivo studies is required. This study aimed to develop peri-implantitis in the rat model by oral contamination with bacteria responsible for PI in humans. The study was carried out in three stages: the extraction of the maxillary first molar to reproduce the human edentation, the mounting of the implant, and finally, the contamination of the device by gavage with Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum and Streptococcus oralis. The hematological examinations showed statistically significant increases for WBCs (white blood cells), Hb (hemoglobin), RBCs (red blood cells), MCH (mean corpuscular hemoglobin), MCHC (mean corpuscular hemoglobin concentration), and PLTs (platelets), but especially for the level of neutrophils and lymphocytes, and the systemic immunoinflammatory index completed the picture related to the inflammatory response triggered as a result of the activity of microorganisms pathogens on oral tissues. By examining the liver and kidney profile, we hypothesized that peri-implantitis is associated with systemic diseases, and the histopathological examination showed peri-implantitis lesions characterized by a marked inflammatory infiltrate with numerous neutrophils and lymphocytes. By corroborating all the results, we successfully developed a rat peri-implantitis model using a mixed bacterial infection through the oral gavage technique.

Induction of Periodontitis Using Bacterial Strains Isolated from the Human Oral Microbiome in an Experimental Rat Model.

Periodontal disease is that condition resulting in the destruction of periodontal tissues, bone resorption, and tooth loss, the etiology of which is linked to immunological and microbiological factors. The aim of this study was to evaluate the potential trigger of periodontal disease in a rat model using bacterial species incriminated in the pathology of human periodontitis and to establish their optimal concentrations capable of reproducing the disease, with the idea of subsequently developing innovative treatments for the condition. In this study, we included 15 male Wistar rats, aged 20 weeks, which we divided into three groups. In each group, we applied ligatures with gingival retraction wire on the maxillary incisors. The ligature and the gingival sac were contaminated by oral gavage with a mixture of fresh cultures of Aggregatibacter actinomycetemcomitans (A.a), Fusobacterium nucleatum (F.n) and Streptococcus oralis (S.o) in concentrations of 108, 109, and 1010 CFU/mL each for 5 days a week for 4 weeks. During the clinical monitoring period of 28 days, overlapped with the period of oral contamination, we followed the expression of clinical signs specific to periodontitis. We also monitored the evolution of body weight and took weekly samples from the oral cavity for the microbiological identification of the tested bacteria and blood samples for hematological examination. At the end of the study, the animals were euthanized, and the ligated incisors were taken for histopathological analysis. The characteristic symptomatology of periodontal disease was expressed from the first week of the study and was maintained until the end, and we were able to identify the bacteria during each examination. Hematologically, the number of neutrophils decreased dramatically (p < 0.0001) in the case of the 109 group, unlike the other groups, as did the number of lymphocytes. Histopathologically, we identified neutrophilic infiltrate in all groups, as well as the presence of coccobacilli, periodontal tissue hyperplasia, and periodontal lysis. In the 109 group, we also observed pulpal tissue with necrotic bone fragments and pyogranulomatous inflammatory reaction. By corroborating the data, we can conclude that for the development of periodontal disease using A.a, F.n, and S.o, a concentration of 109 or 1010 CFU/mL is required, which must necessarily contaminate a ligature thread applied to the level of the rat's dental pack.

Long-term treatment with chloroquine increases lifespan in middle-aged male mice possibly via autophagy modulation, proteasome inhibition and glycogen metabolism.

Previous studies have shown that the polyamine spermidine increased the maximum life span in C. elegans and the median life span in mice. Since spermidine increases autophagy, we asked if treatment with chloroquine, an inhibitor of autophagy, would shorten the lifespan of mice. Recently, chloroquine has intensively been discussed as a treatment option for COVID-19 patients. To rule out unfavorable long-term effects on longevity, we examined the effect of chronic treatment with chloroquine given in the drinking water on the lifespan and organ pathology of male middle-aged NMRI mice. We report that, surprisingly, daily treatment with chloroquine extended the median life span by 11.4% and the maximum life span of the middle-aged male NMRI mice by 11.8%. Subsequent experiments show that the chloroquine-induced lifespan elevation is associated with dose-dependent increase in LC3B-II, a marker of autophagosomes, in the liver and heart that was confirmed by transmission electron microscopy. Quite intriguingly, chloroquine treatment was also associated with a decrease in glycogenolysis in the liver suggesting a compensatory mechanism to provide energy to the cell. Accumulation of autophagosomes was paralleled by an inhibition of proteasome-dependent proteolysis in the liver and the heart as well as with decreased serum levels of insulin growth factor binding protein-3 (IGFBP3), a protein associated with longevity. We propose that inhibition of proteasome activity in conjunction with an increased number of autophagosomes and decreased levels of IGFBP3 might play a central role in lifespan extension by chloroquine in male NMRI mice.

Meropenem antibiotic therapy in acute secondary peritonitis, therapeutic effects superior to other therapies - experimental clinical and histopathological study in the laboratory animal.

AIM: A perforated peptic ulcer is the most common cause of peritonitis through the perforation of the digestive tube, which occurs in a percentage between 2% and 14% of patients diagnosed with peptic ulcer and being associated with a 10% to 30% mortality rate. MATERIALS AND METHODS: Considering the above, we imagined a study, using laboratory animals, in which we produced gastric perforations, then followed their evolution without antibiotic treatment and under antibiotic therapy with Cefuroxime 25 mg∕kg∕24 hours intravenously or Meropenem 40 mg∕kg∕24 hours intravenously, following the tissue changes both macroscopically and microscopically. RESULTS: The study revealed a mortality of 36.6%, most deaths (81.82%) occurred in the first 24 hours after the perforation, all subjects belonging to the group that did not receive antibiotic treatment and the group treated with Cefuroxime. From a clinical point of view (evaluation of the general condition), macroscopically and microscopically, a better evolution of the subjects who received antibiotic therapy can be observed, compared to those who did not receive antibiotic therapy, thus in the case of subjects who received antibiotic therapy, the absence or the presence of a small amount of intraperitoneal fluid, which has a serocitrine appearance, as well as the absence of macroscopic changes at the level of unaffected intraperitoneal organs, can be observed. Microscopically, it can be seen that in the subjects treated with Meropenem, changes in the parietal peritoneum were minimal. CONCLUSIONS: Antibiotic therapy with Meropenem in acute peritonitis has a survival rate comparable to peritoneal lavage and source control.

Histopathological elements analyzed in dynamics in mechanical bowel obstructions - experimental study on laboratory animals.

Bowel obstruction is a syndrome that produces important alterations to the digestive tract, both macroscopically and microscopically. We conducted an experimental study using rats, Wistar strain, as subjects, dividing them into three groups. The group A consisted of six rats and served as control group, in the first day of the experiment a surgical procedure being performed to resect a small bowel and a colic segment to be analyzed microscopically afterwards. The 10 subjects from group B underwent a surgical procedure, in which we induced a mechanical bowel obstruction in the sigmoid colon, while to the 10 subjects from group C we induced a mechanical bowel obstruction in the small bowel. The initial protocol implied to observe the macroscopic modifications from five subjects from each group B and C after two days and afterwards to resect the digestive tract segment adjacent to the obstruction site. After another two days, a similar procedure was planned for the remaining subjects alive from both groups. A few subjects from group C died prematurely and the initial protocol had to be partially modified. The results highlighted an important distension of the digestive tract proximal to the obstruction, with important microscopically reactions, including edema, thrombosis, ischemic lesions and accumulation of polymorphonuclear neutrophils (PMN) and macrophages.

Animal models of orthopaedic infections. A review of rabbit models used to induce long bone bacterial infections.

The development of infections is one of the main complications in orthopaedics, especially in the presence of implants for the osteosynthesis of compound fractures and joint prosthesis. Indeed, foreign materials and implants act as substrates for the adhesion and proliferation of bacterial strains able to produce biofilm, causing peri-implant osteomyelitis. The eradication of biofilm remains a great challenge for the host immune system, as well as for medical and surgical approaches, thus imposing the need for new prophylactic and/or therapeutic strategies in which animal models have an essential role. In vivo orthopaedic models have mainly been used to study the pathogenesis of infections, biofilm behaviour and the efficacy of antimicrobial strategies, to select diagnostic techniques and test the efficacy of novel materials or surface modifications to impede both the establishment of bone infections and the associated septic loosening of implants. Among several models of osteomyelitis and implant-related infections described in small rodents and large animals, the rabbit has been widely used as a reliable and reproducible model of orthopaedic infections. This review examines the relevance of rabbits for the development of clinically representative models by analysing the pros and cons of the different approaches published in the literature. This analysis will aid in increasing our knowledge concerning orthopaedic infections by using this species. This review will be a tool for researchers who need to approach pre-clinical studies in the field of bone infection and have to identify the most appropriate animal model to verify their scientific hypothesis.

Copper Bead Therapy in Severe Bone Infection: A Rabbit Tibial Model.

OBJECTIVE: We investigated the benefits of a local preventive therapy based on copper beads against severe bone infection using a rabbit open tibial fracture model. MATERIALS AND METHODS: Cotton mesh balls soaked in a very high concentration of Staphylococcus aureus ATCC 6538 culture were inoculated in drilled holes of the tibiae of treated and control groups. The treated group was also implanted with small copper beads simultaneously, as prevention therapy. RESULTS: Survival rate in the treated group was 67% compared with 25% in the control group (difference 40%, for a 95% confidence interval: 40%, 93.4%). The few remaining animals in the control group had bone lesions which developed into osteomyelitis, while the tibiae of treated group had clear signs of reparatory processes. Sixty days after inoculation, signs of local-only toxicity were observed in healthy tibia of a separate non-infected control group. Drawbacks of copper toxicity were weighed against the threat of septicaemia and also against prolonged use of powerful systemic antibiotic medications in severe bone contamination. CINICAL SIGNIFICANCE: It was found that the proposed therapy prevented septicaemia and the spread of infection, and it also induced reparatory processes. The findings of this study may be relevant in antisepsis of open fractures in less appropriate medical settings (such as military camps or remote locations), as well as in severe bone infections.

Nanocomposite particles with improved microstructure for 3D culture systems and bone regeneration.

Nano-apatite and gelatin-alginate hydrogel microparticles have been prepared by a one-step synthesis combined with electrostatic bead generation, for the reconstruction of bone defects. Based on the analysis of bone composition, architecture and embryonic intramembranous ossification, a bio-inspired fabrication has been developed. Accordingly, the mineral phase has been in situ synthesized, calcifying the hydrogel matrix while the latter was crosslinked, finally generating microparticles that can assemble into a bone defect to ensure interconnected pores. Although nano-apatite-biopolymer composites have been widely investigated, microstructural optimization to provide improved distribution and stability of the mineral is rarely achieved. The optimization of the developed method progressively resulted in two types of formulations (15P and 7.5P), with 15 and 7.5 (wt%) phosphate content in the initial precursor. The osteolytic potential was investigated using differentiated macrophages. A commercially available calcium phosphate bone graft substitute (Eurocer 400) was incorporated into the hydrogel, and the obtained composites were in vitro tested for comparison. The cytocompatibility of the microparticles was studied with mouse osteoblast-like cell line MC3T3-E1. Results indicated the best in vitro performance have been obtained for the sample loaded with 7.5P. Preliminary evaluation of biocompatibility into a critical size (3 mm) defect in rabbits showed that 7.5P nanocomposite is associated with newly formed bone in the proximity of the microparticles, after 28 days.

The influence of foreign body surface area on the outcome of chronic osteomyelitis.

Reproducible animal models of osteomyelitis close to the clinical scenario are difficult to obtain as the animals either die shortly after inoculation of bacteria or the bone cures itself of infection. Additional materials used as foreign bodies offer increased chances for localized infection due to bacterial attachment and are closer to clinical pathology. Through in vivo experimentation we investigated here the influence of surface area of a series of foreign bodies on the final outcome of the animal model, in terms of reproducibility, survival rate and time necessary for onset of chronic disease. Stainless steel Kirschner wire segments, stainless steel balls and cotton meshes were employed for this purpose. The clinical, microbiological, radiological and histological results obtained were compared with the simple case where no foreign body was used. The follow-up period was 57days. The cotton meshes, which had the highest surface area, were observed to provide the best outcome, with the lowest disease onset time interval (of 1week earlier than the others), the highest survival (of 90%) and disease reproduction rate (90%). The only clinical pattern of the mesh group rabbits was short lived inflammation while the other rabbits presented also some other clinical signs such as rhinorrheas, abscesses, rush and/or dyspnea. Moreover, this model is the most suitable for further treatment studies, as the cotton meshes could be easily removed after disease onset, without any intervention on the bone. This is important, as the treatment would address the bacteria present within the bone parts (marrow, cortex, periosteum etc.) not those forming the biofilm.

Technology transfer of oil-in-water emulsion adjuvant manufacturing for pandemic influenza vaccine production in Romania: Preclinical evaluation of split virion inactivated H5N1 vaccine with adjuvant.

Millions of seasonal and pandemic influenza vaccine doses containing oil-in-water emulsion adjuvant have been administered in order to enhance and broaden immune responses and to facilitate antigen sparing. Despite the enactment of a Global Action Plan for Influenza Vaccines and a multi-fold increase in production capabilities over the past 10 years, worldwide capacity for pandemic influenza vaccine production is still limited. In developing countries, where routine influenza vaccination is not fully established, additional measures are needed to ensure adequate supply of pandemic influenza vaccines without dependence on the shipment of aid from other, potentially impacted first-world countries. Adaptation of influenza vaccine and adjuvant technologies by developing country influenza vaccine manufacturers may enable antigen sparing and corresponding increases in global influenza vaccine coverage capacity. Following on previously described work involving the technology transfer of oil-in-water emulsion adjuvant manufacturing to a Romanian vaccine manufacturing institute, we herein describe the preclinical evaluation of inactivated split virion H5N1 influenza vaccine with emulsion adjuvant, including immunogenicity, protection from virus challenge, antigen sparing capacity, and safety. In parallel with the evaluation of the bioactivity of the tech-transferred adjuvant, we also describe the impact of concurrent antigen manufacturing optimization activities. Depending on the vaccine antigen source and manufacturing process, inclusion of adjuvant was shown to enhance and broaden functional antibody titers in mouse and rabbit models, promote protection from homologous virus challenge in ferrets, and facilitate antigen sparing. Besides scientific findings, the operational lessons learned are delineated in order to facilitate adaptation of adjuvant technologies by other developing country institutes to enhance global pandemic influenza preparedness.

Cerebral ischemia in the aged. Limited anti-inflammatory efficacy of the indomethacin treatment.

Ischemic stroke is a disease of aging and causes high mortality or long-term disability. Diminished neurological recovery after stroke in aged subjects is possibly associated with exaggerated non-specific inflammatory reaction. The focus of the present study was on neurobiological and behavioral differences between young and old rats modulated by indomethacin daily treatment starting at four hours after acute cerebral ischemia in animal model. Our results indicate age-independent positive consequences of non-specific inhibition of inflammation by indomethacin including increased NeuN-positive surviving neurons, reduced infarct volume and enhanced neuroprotective response of innate immune system evidenced by increased Iba1 and Anx3 immunoreactivities and moderately activated microglia in the peri-infarcted area. Quite relevantly, the efficacy of therapy with indomethacin was reduced. In the aged rats, specifically indomethacin is ineffective in inhibiting phagocytic activity, which is probably due failure of the aged brain to up-regulate the expression of several cytokines including TNFα and Cxcl4. At protein level, we observed no change of lysosomal ED1 immunoreactivity under treatment. Our study demonstrates the beneficial anti-inflammatory treatment with indomethacin. However, aging blunted the positive effect.

Sildenafil Reduces Inflammation and Prevents Pulmonary Arterial Remodeling of the Monocrotaline - induced Disease in the Wistar Rats.

OBJECTIVES: Pulmonary arterial hypertension (PAH) is a rare and severe disease with incompletely under stood pathogenesis. PAH is associated with pulmonary arterial remodeling and inflammation. We evaluated the effects of Sildenafil on the Monocrotaline (MCT) -induced disease in Wistar rats, for potential benefit in the early phases of inflammation and vascular remodeling. MATERIAL AND METHODS: MCT-injected rats, MCT-injected sildenafil-treated rats (starting day 1 with 2 x 0.2 mg/day; total of 2 mg/kgc/day) and saline-injected control rats were evaluated at day 14 and day 28 following MCT for pulmonary morphological changes - lesions, inflammation (inflammator y index), arterial morphometry (hypertrophy index), immunohistochemistry for smooth muscle cell marker. OUTCOMES: The administration of sildenafil following MCT significantly reduced the severity of inflammation in the acute stage of the disease (reduction of the inflammatory index by 6.038% (p <0.05)) and prevented pulmonary arterial remodeling (reduction of the hypertrophy index by 7.306% (p<0.001)). It also improved survival in the early phase with a mortality rate during the first 14 days of 4 in the MCT- exposed rats vs 1 in the MCT-exposed sildenafil-treated rate. CONCLUSIONS: Early administration of sildenafil in the MCT experimental PAH improves inflammation and survival, and prevents pulmonary vascular remodeling. Our study suggests that one of the mechanisms involved, besides vasodilatation and anti-proliferative effect, could be a direct anti-inflammatory effect of sildenafil.

Implant microparticles--a new concept for non-invasive cancer therapy.

Some progress in cancer research was possible in recent years mainly due to important advances in nanotechnology. However, clinical use of nanomaterials is still hindered by limitations. In search of better performance and control of inoculated materials, the efficiency and toxicity of SBBC implant particles was assessed. B16 tumoral cells (murine melanoma) were subjected to SBCC particles using in vitro and in vivo experimental models. In vitro experiments concerning the growth inhibition of tumoral cells using SBCC particles were performed by Flow Cytometry and by MTT Assay. In vivo experimental model (C57BL/6 mice) was used to complete this investigation: weight, viability and tumoral dimension were monitored. An anti-proliferative activity on B16 tumoral cells and an ability to produce apoptosis were observed. A reduction of tumoral volume and a 54% survival rate in the treated animals compared to the controls was obtained. Our preliminary results showed that the SBCC implants were effective against B16 melanoma cells, while there is no toxicity associated.

Evaluation of the efficacy of a specific hyperimmune serum in experimental influenza infection in mice.

Serotherapy still remains a way of treatment in some diseases, and it could be consider superior to any other mode of action because the protecting substances of the body are the products of the organism itself. The aim of the study was to establish an "in vivo" method for testing the efficacy of therapeutic serum. Hyperimmune serum for influenza A/PR8/34 viral strain, was prepared in sheep, and tested for inhibition of haemagglutination and microneutralisation. Seroprotection was evaluated in mice one day after being challenged with a lethal dose of the same virus. Our study shows that protection occurred in all mice treated with undiluted hyperimmune serum one day post infection (no clinical signs, faster recovery of the body weight after the first three days of the infection, all mice survived).