Cecal Slurry as an Alternative Model to Cecal Ligation and Puncture for the study of Sepsis-induced Cardiovascular Dysfunction.

ABSTRACT: Sepsis is a life-threatening condition widely studied by animal models. Cecal ligation and perforation (CLP) is still regarded as the gold standard model for sepsis. However, CLP has limitations due to its invasiveness and variability. Cecal slurry injection (CS) model is a non-surgical and thus less invasive alternative. However, the lack of standardization of the CS model in the literature limits its practical application. Additionally, it is not well studied whether CS model reproduces septic cardiovascular dysfunction in rats, which is a crucial issue in septic patients. Thus, this study aimed to standardize the CS model in Wistar rats and evaluate sepsis-induced cardiovascular dysfunction compared to CLP. Our results showed that CS model induced important features of sepsis cardiovascular dysfunction 24 hours after its onset, such as hypotension, tachycardia, decreased contractile response to vasoconstrictors both in vivo and ex vivo as well changes in renal blood flow. Increases in blood lactate, AST, ALT, creatinine, and urea indicated organ dysfunction. CS model also induced increased production of nitric oxide metabolites and bacterial spread to tissues. CS model causes less animal suffering, it is a non-surgical model and more important, it replicates the cardiovascular dysfunction induced by sepsis with better homogeneity than CLP. Therefore, CS model serves as an alternative and possibly as a better model for sepsis research.

EARLY BLOOD LACTATE AS A BIOMARKER FOR CARDIOVASCULAR COLLAPSE IN EXPERIMENTAL SEPSIS.

ABSTRACT: Cecal ligation and puncture (CLP) is the gold standard model for studying septic shock, which is characterized by hypotension and hyporeactivity to vasoconstrictors. However, approximately 30% of CLP animals do not exhibit cardiovascular changes, requiring more replicates because of the high variability of the model. Therefore, biomarkers enabling the early prediction of cardiovascular collapse in sepsis would greatly benefit sepsis nonclinical studies, refining experimental models and improving clinical translation. Thus, this study aimed to test whether the early increase in lactate levels could predict hypotension and hyporesponsiveness to vasoconstrictors in a rat model of sepsis. Male and female Wistar rats were subjected to CLP or sham procedure. Tail blood lactate was measured 6, 12, and 24 h after surgery. Then, inflammatory, biochemical, and hemodynamic parameters were evaluated. Rats subjected to CLP developed hypotension, hyporesponsiveness to vasoconstrictors, an intense inflammatory process, and increased plasma markers of organ dysfunction. By using receiver operating characteristics curve analysis, we have established that a lactate value of 2.45 mmol/L can accurately discriminate between a rat exhibiting a normal vasoconstrictive response and a vasoplegic rat with 84% accuracy (area under the curve: 0.84; confidence interval [CI]: 0.67-1.00). The sensitivity, which is the ability to identify a diseased rat (true positive), was 75% (CI: 41-95), and the true negative rate was 81% (CI: 57-93). Therefore, early measurement of lactate levels in sepsis could serve as a valuable biomarker for distinguishing vasoplegic rats from those exhibiting normal vasoconstrictive responses.

Absence of medication-related jaw osteonecrosis after treatment with strontium ranelate in ovariectomized rats.

This study aimed to evaluate the potential of strontium ranelate (SR) in medication-related jaw osteonecrosis (MRONJ) after tooth extraction in ovariectomized rats. Thirty ovariectomized rats were divided into three groups (n = 10): bisphophonate (BP) group (zoledronic acid; 0.4 mg/kg/week), SR group (625 mg/kg/day), and control group (saline solution). The lower first molars were extracted after 60 days of drug therapy. Drug administration was continued for another 30 days after tooth extraction. The mandibles were subjected to clinical, histological, radiographic, and microtomographic evaluations. Only the BP group showed clinical changes, characterized by the presence of 70% (n = 7) and 20% (n = 2) of ulcers and extraoral fistulas. Radiographic evaluation demonstrated bone sequestration only in the BP group (n = 7, 70%). Microtomographic analysis revealed increased bone porosity after ovariectomy, particularly in the the control group (p < 0.05). The BP group showed a higher bone surface density, bone volume, and trabecular number than SR and control groups, but with less trabecular separation (p < 0.05). All the animals in the BP group demonstrated histological osteonecrosis. There was no evidence of osteonecrosis in the control and SR groups, which was characterized by the absence of empty osteocyte gaps and associated with the gradual healing of the extraction area. Also, an increased number of blood vessels and a reduced number of osteoclasts were observed in the SR group (p < 0.05). Therefore, SR treatment increased angiogenesis and osteoclastogenesis in the healing socket and was not associated with MRONJ development after tooth extraction in ovariectomized rats.

Effect of pentoxifylline and α-tocopherol on medication-related osteonecrosis of the jaw in rats: Before and after dental extraction.

OBJECTIVE: Evaluate the effect of pentoxifylline and α-tocopherol administration in the prevention or treatment of medication-related jaw osteonecrosis (MRONJ). METHODOLOGY: Sixty Wistar rats were divided into three prevention (C-prev, BP-prev and BP/PT-prev) and three treatment groups (C-treat, BP-treat and BP/PT-treat), n = 10. The animals in the BP-prev, BP/PT-prev, BP-treat and BP/PT-treat groups received zoledronic acid (0.1 mg/kg) for 12 weeks, while the animals in the C-prev and C-treat groups received saline solution. At week 6, all animals underwent tooth extraction. Between week 5 and week 12, the BP/PT-prev group was treated with pentoxifylline (50 mg/kg/day) and α-tocopherol (80 mg/kg/day), with euthanasia at the end of week 12. The BP/PT-treat group received the same drug protocol, but it was performed between week 12 and week 16, with euthanasia at the end of week 16. Afterwards, the presence of osteonecrosis was evaluated by clinical analysis, radiographic and histological. RESULTS: BP/PT-treat group showed a reduction in the histological incidence of osteonecrosis by 50%, decrease the percentage of empty osteocyte gaps and the necrotic area, decrease the presence of bone sequestration and increase the number of osteocytes and alveolar blood flow (p < 0.05). However, BP/PT-prev group showed only a reduction in the necrotic area percentage when compared to BP-prev (p < 0.05). CONCLUSIONS: Pentoxifylline and α-tocopherol administration before tooth extraction was not effective in preventing MRONJ. However, this drug protocol was able to reduce MRONJ manifestation when administrate after discontinuation of bisphosphonate, thus it can be considered as a viable strategy for the treatment of this pathological condition.

Absence of medication-related jaw osteonecrosis after treatment with strontium ranelate in ovariectomized rats

Abstract This study aimed to evaluate the potential of strontium ranelate (SR) in medication-related jaw osteonecrosis (MRONJ) after tooth extraction in ovariectomized rats. Thirty ovariectomized rats were divided into three groups (n = 10): bisphophonate (BP) group (zoledronic acid; 0.4 mg/kg/week), SR group (625 mg/kg/day), and control group (saline solution). The lower first molars were extracted after 60 days of drug therapy. Drug administration was continued for another 30 days after tooth extraction. The mandibles were subjected to clinical, histological, radiographic, and microtomographic evaluations. Only the BP group showed clinical changes, characterized by the presence of 70% (n = 7) and 20% (n = 2) of ulcers and extraoral fistulas. Radiographic evaluation demonstrated bone sequestration only in the BP group (n = 7, 70%). Microtomographic analysis revealed increased bone porosity after ovariectomy, particularly in the the control group (p < 0.05). The BP group showed a higher bone surface density, bone volume, and trabecular number than SR and control groups, but with less trabecular separation (p < 0.05). All the animals in the BP group demonstrated histological osteonecrosis. There was no evidence of osteonecrosis in the control and SR groups, which was characterized by the absence of empty osteocyte gaps and associated with the gradual healing of the extraction area. Also, an increased number of blood vessels and a reduced number of osteoclasts were observed in the SR group (p < 0.05). Therefore, SR treatment increased angiogenesis and osteoclastogenesis in the healing socket and was not associated with MRONJ development after tooth extraction in ovariectomized rats.