Since the emergence of SARS-CoV-2 at the end of 2019, 64 candidate vaccines are in clinical development and 173 are in the pre-clinical phase. Five types of vaccines are currently approved for emergency use in many countries (Inactivated, Sinopharm; Viral-vector, Astrazeneca, and Gamaleya Research Institute; mRNA, Moderna, and BioNTech/Pfizer). The main challenge in this pandemic was the availability to produce an effective vaccine to be distributed to the world’s population in a short time. Herein, we developed a whole virus NRC-VACC-01 inactivated candidate SARS-CoV-2 vaccine and tested its safety and immunogenicity in laboratory animals. In the preclinical studies, we used four experimental animals (mice, rats, guinea pigs, and hamsters). Antibodies were detected as of week three post vaccination and continued up to week ten in the four experimental models. Safety evaluation of NRC-VACC-01 inactivated candidate vaccine in rats revealed that the vaccine was highly tolerable. By studying the effect of booster dose in the immunological profile of vaccinated mice, we observed an increase in neutralizing antibody titers after the booster shot, thus a booster dose was highly recommended after week three or four. Challenge infection of hamsters showed that the vaccinated group had lower morbidity and shedding than the control group. A phase I clinical trial will be performed to assess safety in human subjects.

Liver fibrosis is a health concern that leads to organ failure mediated via production of inflammatory cytokines and fibrotic biomarkers. This study aimed to explore the protective effect of tadalafil, a phosphodiesterase-5 inhibitor, against thioacetamide (TAA)-induced liver fibrosis. Fibrosis was induced by administration of TAA (200 mg/kg, i.p.) twice weekly for 6 weeks. Serum transaminases activities, liver inflammatory cytokines, fibrotic biomarkers, and liver histopathology were assessed. TAA induced marked histopathological changes in liver tissues coupled with elevations in serum transaminases activities. Furthermore, hepatic content of nitric oxide and tumor necrosis factor-alpha, interleukin-6, and interleukin-1 beta were elevated, together with a reduction of interleukin-10 in the liver. In addition, TAA increased hepatic contents of transforming growth factor-beta, hydroxyproline, alpha-smooth muscle actin, and gene expression of collagen-1. Pretreatment with tadalafil protected against TAA-induced liver fibrosis, in a dose-dependent manner, as proved by the alleviation of inflammatory and fibrotic biomarkers. The effects of tadalafil were comparable with that of silymarin, a natural antioxidant, and could be assigned to its anti-inflammatory and anti-fibrotic properties.

Objective This study evaluated hepatoprotective effect of aescin (AES) and diosmin (DIO), individually or in low-dose combination in chemically induced liver injury in rats. Rats were divided into 6 groups; Group 1, control, Group 2, injected with a single dose of a mixture of corn oil and carbon tetrachloride (CCl4) to induce hepatic toxicity. Before CCl4 injection, Groups 3–6 were treated daily for 14 days with silymarin (SIL) (200 mg/kg), aescin (AES; 3.6 & 1.75 mg/kg), Diosmin (DIO; 100 & 50 mg/kg). Serum samples were analyzed for different liver function, oxidative stress and antioxidant markers. Moreover, inflammation and tissue damage were confirmed by histological staining of liver tissue sections. Results Results indicated that CCl4 elevated serum levels of all assessed liver function markers and decreased levels of key antioxidants. Administration of AES and/or DIO significantly reversed all those CCl4-induced effects. Histopathological study showed disruption of the hepatic architecture, necrosis and inflammatory cells and depositions of glycogen and protein in the tissues of CCl4-treated group. Pretreatment with DIO and/or AES significantly improved histopathological structure of liver tissue. In conclusion, low-dose combination of AES and DIO exhibited significant and preferential hepatoprotective activity compared to individual treatment with AES or DIO.

In malathion intoxicated rats, the neuronal NOS inhibitor 7-NI and to much less extent l-NAME were able to protect the brain and liver tissue integrity along with improvement in oxidative stress parameters. The decrease in DNA damage of peripheral blood lymphocytes by NOS inhibitors also suggests the involvement of nitric oxide in this process.

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