The hepatoprotective effect of sitagliptin against hepatic ischemia reperfusion-induced injury in rats involves Nrf-2/HO-1 pathway

BackgroundOxidative stress and inflammation play a key role in the development of hepatic ischemia reperfusion (HIR)-induced injury. Nuclear factor-erythroid 2-related factor-2 (Nrf-2) is a main regulator of numerous genes, encoding cytoprotective molecules including heme oxygenase-1 (HO-1). Sitagliptin (Sit) is an incretin enhancer acting via inhibition of dipeptidyl peptidase-4 (DPP-4) enzyme. This study was undertaken to investigate the ability of Sit to prevent the hepatic pathological changes of HIR induced injury and to modify Nrf-2 and its target HO-1.MethodsPringle's maneuver was used to induce total HIR in adult male rats that were randomly assigned into 4 groups. Group1 (sham-operated control), Group 2 (sham-operated + Sit-control group), Group 3 (HIR non-treated), and Group 4 (HIR + Sit). Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities together with hepatic contents of malondialdhyde (MDA), nitric oxide (NO) and reduced glutathione (GSH) and superoxide dismutase (SOD) activity were evaluated. Hepatic tissue mRNA of Nrf-2 and protein content of HO-1 along with histopathological examination and scoring of hepatic injury were performed.ResultsSit caused a significant reduction in ALT and AST activities together with attenuation of HIR-induced histopathological liver injury. Effect of Sit was associated with decreased hepatic level of MDA and NO with increased GSH level and SOD activity. Non-treated rats with HIR showed an increase in Nrf-2 mRNA expression and HO-1 content in hepatic tissue which was further increased by Sit treatment.ConclusionsThese results indicate that hepatoprotective activity of Sit against HIR is attributed at least in part to modulation of Nrf-2/ HO-1 signaling pathway.     

Effect of pregnancy on cooling tone and rhythmic contractions of the rat urinary bladder

Objectives

Pregnancy is a physiological alteration that can affect urinary bladder. Cooling of urinary bladder smooth muscle is known as a potent stimulus to micturition due to an increase in muscle tone. The current study investigates the effects of pregnancy on cooling tone and on the rhythmic contractions of the urinary bladder.

Methods

Twenty-four rats were used in this study as control group (non-pregnant) and pregnant group (18–20-day pregnancy). Isolated rat urinary muscle strips were suspended in organ baths containing Krebs’ solution for isometric tension recording.

Results

Cooling from 37 to 5 °C induced a rapid and reproducible increase in basal tone, proportional to cooling temperature. Cooling also increased the rhythmic activity (amplitude and frequency) at 30 and 25 °C, then decreased at 20 °C, and abolished at 15–5 °C. These responses were more pronounced in pregnant group than in control group. Rhythmic contractions were abolished in calcium-free, EGTA (1 mM)-containing Krebs’ solution and in the presence of nifedipine, while they were not affected by CPA or TTX in both groups. Our investigation showed that the influx of extracellular calcium is important in inducing the rhythmic contractions.

Conclusions

Pregnancy increases cooling-induced contraction in pregnant rat urinary preparations and its rhythmic contractions including amplitude and frequency than non-pregnant rat. Rhythmic contractions are myogenic in nature and highly extracellular calcium dependent. They may play a crucial role in urinary bladder overactivity and incontinence during pregnancy.

     

The role of cardamom on the hazardous effects of depleted uranium in cerebellum and midbrain of albino rats

The present study aimed to investigate uranium hazardous effects, as well as the ameliorative effects of cardamom on the cerebellum and midbrain of adult male albino rats at different time intervals. The administration of 40 mg/Kg of uranyl acetate dehydrate (UAD) caused a significant decrease in Pi, K⁺ ions contents and GSH level while, a significant increase in Na⁺ and Ca²⁺ ions content and MDA level were observed, which may be due to the decrease in ATP synthesis and the inhibition of Na⁺/K⁺ ATPase activity. Also, UDA has the ability to increase lipid peroxidation and decrease GSH synthesis. On the other hand, the administration of 250 mg/kg of cardamom extract induced significant increase in Pi, K⁺ ions content and GSH level, while it caused a significant decrease in Na⁺, Ca²⁺ ions content and MDA level which may be due to the increase of ATP synthesis and its anticonvulsant and antioxidant effects. It could be concluded that the pre -and post-treatment with cardamom could ameliorate the hazardous effects of UAD intoxication.     

Effects of chronic ethanol and vitamin C administration on production of tumor necrosis factor-alpha and interleukin-6 in rats

Chronic alcoholism complicated by alcoholic liver disease (ALD) is characterized by activation of inflammatory responses. Alcohol intake increases gut permeability allowing substances such as lipopolysaccharides (LPS) which are strong inducers of proinflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) to enter the circulation. Vitamin C is an antioxidant with many cellular activities seemed to protect cells against alcohol-induced peroxidation. In present study, serum levels of TNF-alpha and IL-6 were measured by ELISA method in four groups of albino rats, each group consists of 10 rats. Group (I) was untreated group (control), group (II) was treated with ethanol, group (III) was treated with ascorbic acid and group (IV) was treated with ethanol + ascorbic acid. Results revealed that both TNF-alpha and IL-6 serum levels were very highly significantly increased in group (II) and (IV) than control group (1) (P < 0.001). Group (III) showed significantly (P < 0.001) decreased TNF-alpha serum level than group (II) and (IV) while it showed significantly (P < 0.001) increased IL-6 serum level than control group (I) and also significantly decreased IL-6 serum level than group (IV). Serum IL-6 level was significantly (P < 0.01) decreased in group (III) than (II). These results indicate that serum levels of the proinflammatory cytokines TNF-alpha and IL-6 may serve as predictive biomarkers for progression of ALD. In addition, using TNF-alpha neutralizing agent (or its antagonist)/or IL-6 as an anti-apoptotic factor could be useful as a treatment strategy of ALD.     

Apparent diffusion coefficient measurements in the differentiation between benign and malignant neck masses

Aim

Evaluate the role of ADC value measurements in the differentiation between benign and malignant neck masses.

Methods

From April 2011 to February 2013, prospective study was conducted on 30 patients (17 male and 13 female), with the mean age 43.3 ± 6 years. Collected from wards and clinics of General Surgery and Otolaryngology Departments complaining from neck masses. MRI, Diffusion-Weighted Imaging (b value 0, 100, 500 and 1000 s/mm) and ADC value calculation were performed and the results were correlated with histopathological results and/or follow up.

Results

The present study include 30 patients (Lymphadenopathy {(n = 15) (11 as single entity), (4 associated with other entities)}, Focal thyroid swelling (n = 5), Salivary gland masses (n = 3) {Parotitis (1 case), Parotid carcinoma (2 cases)}, Nasopharyngeal masses (n = 5), Oropharyngeal masses (n = 2), Ludwig angina (n = 2) and Laryngeal masses (n = 2).The mean ADC of the malignant neck masses was (0.699 + 0.267 × 10^-3 mm²/s) while that of the benign masses was (1.879 + 0.751 × 10^-3 mm²/s).The results confirmed by biopsy in 23 cases and follow up (7 cases).The sensitivity, specificity, PPV, NPV and overall accuracy of quantitative diffusion WI in differentiating benign from malignant neck masses were 95.4%, 83.3%, 95.4%, 83%, and 92%.

Conclusion

ADC value calculation are promising noninvasive imaging approach that can be used in distinguishing between benign and malignant neck masses. Benign lesions have higher mean ADC values than malignant lesions, the cutoff value was 1.25 × 10^-3 mm²/s while 0.8 × 10^-3 mm²/s in thyroid lesions.     

Bone marrow stroma-derived PGE2 protects BCP-ALL cells from DNA damage-induced p53 accumulation and cell death

Background

B cell precursor acute lymphoblastic leukaemia (BCP-ALL) is the most common paediatric cancer. BCP-ALL blasts typically retain wild type p53, and are therefore assumed to rely on indirect measures to suppress transformation-induced p53 activity. We have recently demonstrated that the second messenger cyclic adenosine monophosphate (cAMP) through activation of protein kinase A (PKA) has the ability to inhibit DNA damage-induced p53 accumulation and thereby promote survival of the leukaemic blasts.Development of BCP-ALL in the bone marrow (BM) is supported by resident BM-derived mesenchymal stromal cells (MSCs). MSCs are known to produce prostaglandin E₂ (PGE₂) which upon binding to its receptors is able to elicit a cAMP response in target cells. We hypothesized that PGE₂ produced by stromal cells in the BM microenvironment could stimulate cAMP production and PKA activation in BCP-ALL cells, thereby suppressing p53 accumulation and promoting survival of the malignant cells.

Methods

Primary BCP-ALL cells isolated from BM aspirates at diagnosis were cocultivated with BM-derived MSCs, and effects on DNA damage-induced p53 accumulation and cell death were monitored by SDS-PAGE/immunoblotting and flow cytometry-based methods, respectively. Effects of intervention of signalling along the PGE₂-cAMP-PKA axis were assessed by inhibition of PGE₂ production or PKA activity. Statistical significance was tested by Wilcoxon signed-rank test or paired samples t test.

Results

We demonstrate that BM-derived MSCs produce PGE₂ and protect primary BCP-ALL cells from p53 accumulation and apoptotic cell death. The MSC-mediated protection of DNA damage-mediated cell death is reversible upon inhibition of PGE₂ synthesis or PKA activity. Furthermore our results indicate differences in the sensitivity to variations in p53 levels between common cytogenetic subgroups of BCP-ALL.

Conclusions

Our findings support our hypothesis that BM-derived PGE₂, through activation of cAMP-PKA signalling in BCP-ALL blasts, can inhibit the tumour suppressive activity of wild type p53, thereby promoting leukaemogenesis and protecting against therapy-induced leukaemic cell death. These novel findings identify the PGE₂-cAMP-PKA signalling pathway as a possible target for pharmacological intervention with potential relevance for treatment of BCP-ALL.