Protection by sildenafil and theophylline of lead acetate-induced oxidative stress in rat submandibular gland and saliva

Effects of lead exposure on salivary glands of rats: insights into the oxidative biochemistry and glandular morphology

This study aimed to investigate the effects of lead (Pb) exposure on parotid and submandibular glands through morphological aspects as well as the systemic and salivary gland redox state. Male Wistar rats were exposed to 50 mg/kg/day of Pb-acetate or distilled water by intragastric gavage for 55 days (n = 40). Blood samples were used for lipid peroxidation (LPO), glutathione (GSH), and trolox equivalent antioxidant capacity (TEAC) assays. Samples of salivary glands were analyzed by LPO, nitrites (NO), and antioxidant capacity against peroxyl radicals (ACAP) levels. Morphometric analyses (total stromal area [TSA], total parenchyma area [TPA], total ductal area [TDA], and total acinar area [TAA]) and immunohistochemistry for cytokeratin-19 (CK-19), metallothionein I/II (MT I/II), and anti-smooth muscle actin (α-SMA) were performed. The results revealed that exposure to Pb triggered systemic oxidative stress represented by lower GSH levels and increased TBARS/TEAC ratio in blood plasma. ACAP was reduced, while NO and LPO were increased in both parotid and submandibular. The morphological analyses showed increase on MT I/II expression, reduced CK-19 expression in both glands, and α-SMA reduced the immunostaining only in the parotid glands. The morphometric analyses revealed an increase in TPA in both glands, while TAA was reduced only in submandibular glands and TDA was increased only in parotid glands. Our findings are pioneer in showing that long-term exposure to Pb is able to promote blood and glandular oxidative stress associated with cellular, morphological, and biochemical damage in both parotid and submandibular glands.

Pharmacological activation of soluble guanylate cyclase improves vascular graft function

OBJECTIVES

Ischaemia-reperfusion injury impairs the nitric oxide/soluble guanylate cyclase/cyclic guanosine monophosphate (cGMP) signalling pathway and leads to vascular dysfunction. We assessed the hypothesis that the soluble guanylate cyclase activator cinaciguat would protect the vascular graft against ischaemia-reperfusion injury.

METHODS

In the treatment groups, rats (n = 8/group) were pretreated with either intravenous saline or intravenous cinaciguat (10 mg/kg) 2 h before an aortic transplant. Aortic grafts were stored for 2 h in saline and transplanted into the abdominal aorta of the recipients. Two hours after the transplant, the grafts were harvested and mounted in an organ bath. Vascular function of the grafts was investigated in the organ bath. Terminal deoxynucleotidyl transferase dUTP nick end labelling, cluster of differentiation 31, caspase-3, endothelial nitric oxide synthase, cGMP, nitrotyrosine and vascular cell adhesion molecule 1 immunochemical reactions were also investigated.

RESULTS

Pretreatment with cinaciguat significantly improved endothelium-dependent maximal relaxation 2 h after reperfusion compared with the saline group (maximal relaxation control: 96.5 ± 1%, saline: 40.4 ± 3% vs cinaciguat: 54.7 ± 2%; P < 0.05). Pretreatment with cinaciguat significantly reduced DNA fragmentation and nitro-oxidative stress; decreased the caspase-3 and vascular cell adhesion molecule 1 scores; and increased endothelial nitric oxide synthase, cGMP and cluster of differentiation 31 scores.

CONCLUSIONS

Our results demonstrated that enhancement of cGMP signalling by pharmacological activation of the soluble guanylate cyclase activator cinaciguat might represent a beneficial therapy for treating endothelial dysfunction of arterial bypass graft during cardiac surgery.

The Phosphodiesterase Type 5 Inhibitor Sildenafil Improves DNA Stability and Redox Homeostasis in Systemic Sclerosis Fibroblasts Exposed to Reactive Oxygen Species

Systemic sclerosis (SSc) is a multi-system connective tissue disease characterized by the increased deposition of extracellular matrix proteins such as collagen and fibronectin. Although the pathogenesis is not completely understood, a number of studies suggest that free radicals could be the major contributors to the disease. Indeed, different studies demonstrated how oxidative stress could contribute to the fibrotic process activation at the level of the skin and visceral organs. Emerging evidences highlight the beneficial effects of sildenafil, a phosphodiesterase type 5 inhibitor (PDE5i), which protects different cell lines from the cell damage induced by reactive oxygen species (ROS). These data make sildenafil a good candidate for therapeutic treatment aimed to protect biological macromolecules against oxidative damage, thus preserving cell viability. The purpose of this study was to evaluate the sensitivity of SSc dermal fibroblasts to an oxidative insult and the ability for sildenafil to prevent/reduce the DNA damage due to ROS action. Additionally, we evaluated the capacity for sildenafil to influence redox homeostasis and cytotoxicity, as well as cell proliferation and cell cycle progression. We demonstrated that SSc fibroblasts have an increased sensitivity to a pro-oxidant environment in comparison to healthy controls. The sildenafil treatment reduced ROS-induced DNA damage, counteracted the negative effects of ROS on cell viability and proliferation, and promoted the activity of specific enzymes involved in redox homeostasis maintenance. To our knowledge, in this report, we demonstrate, for the first time, that sildenafil administration prevents ROS-induced instability in human dermal fibroblasts isolated by SSc patients. These results expand the use of PDE5i as therapeutic agents in SSc by indicating a protective role in tissue damage induced by oxidative insult.

Hetero-Tricyclic Lead Scaffold as Novel PDE5A Inhibitor for Antihypertensive Activity: In Silico Docking Studies

Objective:

To screen the phytochemicals for phosphodiesterase 5A (PDE5A) inhibitory potential and identify lead scaffolds of antihypertensive phytochemicals using in silico docking studies.

Methods:

In this perspective, reported 269 antihypertensive phytochemicals were selected. Sildenafil, a PDE5A inhibitor was used as the standard. In silico docking study was carried out to screen and identify the inhibiting potential of the selected phytochemicals against PDE5A enzyme using vLife MDS 4.4 software.

Results:

Based on docking score, π-stacking, H-bond and ionic interactions, 237 out of 269 molecules were selected which have shown one or more interactions. Protein residue Gln817A was involved in H-boding whereas Val782A, Phe820A and Leu804A were involved in π-stacking interaction with ligand. The selected 237 phytochemicals were structurally diverse, therefore 82 out of 237 molecules with one or more tricycles were filtered out for further analysis. Amongst tricyclic molecules, 14 molecules containing nitrogen heteroatom were selected for lead scaffold identification which finally resulted in three different basic chemical backbones like pyridoindole, tetrahydro-pyridonaphthyridine and dihydro-pyridoquinazoline as lead scaffolds.

Conclusion:

In silico docking studies revealed that nitrogen-containing tetrahydro-pyridonaphthyridine and dihydro-pyridoquinazoline tricyclic lead scaffolds have emerged as novel PDE5A inhibitors for antihypertensive activity. The identified lead scaffolds may provide antihypertensive lead molecules after its optimization.

Targeting Phosphodiesterase-5 by Vardenafil Improves Vascular Graft Function

OBJECTIVES

Ischaemia reperfusion (IR) injury occurs during vascular graft harvesting and implantation during vascular/cardiac surgery. Elevated intracellular cyclic guanosine monophosphate (cGMP) levels contribute to an effective endothelial protection in different pathophysiological conditions. The hypothesis that the phosphodiesterase-5 inhibitor vardenafil would protect vascular grafts against IR injury by upregulating the nitric oxide-cGMP pathway in the vessel wall of the bypass graft was investigated.

METHODS

Lewis rats (n = 6-7/group) were divided into Group 1, control; Group 2, donor rats received intravenous saline; Group 3, received intravenous vardenafil (30 μg/kg) 2 h before explantation. Whereas aortic arches of Group 1 were immediately mounted in an organ bath, aortic segments of Groups 2 and 3 were stored for 2 h in saline and transplanted into the abdominal aorta of the recipient. Two hours after transplantation, the implanted grafts were harvested. Endothelium dependent and independent vasorelaxations were investigated. TUNEL, CD-31, ICAM-1, VCAM-1, α-SMA, nitrotyrosine, dihydroethidium and cGMP immunochemistry were also performed.

RESULTS

Compared with the control, the saline group showed significantly attenuated endothelium dependent maximal relaxation (R_max) 2 h after reperfusion, which was significantly improved by vardenafil supplementation (R_max control, 91 ± 2%; saline 22 ± 2% vs. vardenafil 39 ± 4%, p < .001). Vardenafil pre-treatment significantly reduced DNA fragmentation (control 9 ± 1%, saline 66 ± 8% vs. vardenafil 13 ± 1%, p < .001), nitro-oxidative stress (control 0.8 ± 0.3, saline 7.6 ± 1.3 vs. vardenafil 3.8 ± 1, p = .036), reactive oxygen species level (vardenafil 36 ± 4, control 34 ± 2 vs. saline 43 ± 2, p = .049), prevented vascular smooth muscle cell damage (control 8.5 ± 0.7, saline 4.3 ± 0.6 vs. vardenafil 6.7 ± 0.6, p = .013), decreased ICAM-1 (control 4.1 ± 0.5, saline 7.0 ± 0.9 vs. vardenafil 4.4 ± 0.6, p = .031), and VCAM-1 score (control 4.4 ± 0.4, saline 7.3 ± 1.0 vs. vardenafil 5.2 ± 0.4, p = .046) and increased cGMP score in the aortic wall (control 11.2 ± 0.8, saline 6.5 ± 0.8 vs. vardenafil 8.9 ± 0.6, p = .016). The marker for endothelial integrity (CD-31) was also higher in the vardenafil group (control 74 ± 4%, saline 22 ± 2% vs. vardenafil 40 ± 3%, p = .008).

CONCLUSIONS

The results support the view that impairment of intracellular cGMP signalling plays a role in the pathogenesis of the endothelial dysfunction of an arterial graft after bypass surgery, which can effectively be prevented by vardenafil. Its clinical use as preconditioning drug could be a novel approach in vascular/cardiac surgery.

Hydrogen peroxide inhibits Ca2+ efflux through plasma membrane Ca2+-ATPase in mouse parotid acinar cells

Intracellular Ca²⁺ mobilization is closely linked with the initiation of salivary secretion in parotid acinar cells. Reactive oxygen species (ROS) are known to be related to a variety of oxidative stress-induced cellular disorders and believed to be involved in salivary impairments. In this study, we investigated the underlying mechanism of hydrogen peroxide (H₂O₂) on cytosolic Ca²⁺ accumulation in mouse parotid acinar cells. Intracellular Ca²⁺ levels were slowly elevated when 1 mM H₂O₂ was perfused in the presence of normal extracellular Ca²⁺. In a Ca²⁺-free medium, 1 mM H₂O₂ still enhanced the intracellular Ca²⁺ level. Ca²⁺ entry tested using manganese quenching technique was not affected by perfusion of 1 mM H₂O₂. On the other hand, 10 mM H₂O₂ induced more rapid Ca²⁺ accumulation and facilitated Ca²⁺ entry from extracellular fluid. Ca²⁺ refill into intracellular Ca²⁺ store and inositol 1,4,5-trisphosphate (1 µM)-induced Ca²⁺ release from Ca²⁺ store was not affected by 1 mM H₂O₂ in permeabilized cells. Ca²⁺ efflux through plasma membrane Ca²⁺-ATPase (PMCA) was markedly blocked by 1 mM H₂O₂ in thapsigargin-treated intact acinar cells. Antioxidants, either catalase or dithiothreitol, completely protected H₂O₂-induced Ca²⁺ accumulation through PMCA inactivation. From the above results, we suggest that excessive production of H₂O₂ under pathological conditions may lead to cytosolic Ca²⁺ accumulation and that the primary mechanism of H₂O₂-induced Ca²⁺ accumulation is likely to inhibit Ca²⁺ efflux through PMCA rather than mobilize Ca²⁺ ions from extracellular medium or intracellular stores in mouse parotid acinar cells.

Clinical Aspects of Opium Adulterated with Lead in Iran: A Review

Adulteration of drugs with poisonous substances during production or consumption has caused numerous health problems. Among contaminants that have the potential of producing poisonous effects are the heavy metals lead, arsenic and thallium that make up an important group of toxic substances. The emergence of these new health problems related to opioid abuse has precipitated this MiniReview on the status of the most hazardous and common opioid adulterants. In fact, adulterated opium is a major public health problem and can threaten the health of users. In this study, we searched for information on opium, opiates, lead poisoning, toxicity, intoxication, Iran and heavy metals in the TUMS Digital Library, PubMed, Scopus, EMBASE and Google Scholar bibliographical databases. This MiniReview primarily included articles on lead poisoning, signs and symptoms, and management in opioid-dependent individuals. Exclusion criteria were articles dealing with animal studies, specific paediatric studies, adulterants other than heavy metals and substances other than opioids. Adulterated opium is one of the new sources of exposure to lead and has precipitated an increase in lead-poisoned cases owing to the widespread use of opium. The toxicology of lead and general guidelines on diagnosis and treatment of lead poisoning is briefly reviewed. The symptoms of lead toxicity mimic several diseases often leading to unnecessary diagnostic methods, misdiagnoses and even surgery. Finally, owing to the fact that lead toxicity shows non-specific signs and symptoms, screening for this disease, by taking blood samples and assessing blood lead levels in high-risk people, should be given an utmost priority. It is recommended that screening tests are adopted and applied for any drug-abusing patient with non-specific subacute signs and symptoms like abdominal pain, constipation and anaemia.

Monitoring the biochemical alterations in hypertension affected salivary gland tissues using Fourier transform infrared hyperspectral imaging

FTIR imaging shows biochemical differences between salivary glands from control and hypertensive rats.

High Performance Liquid Chromatography-mass Spectrometry Analysis of High Antioxidant Australian Fruits with Antiproliferative Activity Against Cancer Cells

BACKGROUND

High antioxidant capacities have been linked to the treatment and prevention of several cancers. Recent reports have identified several native Australian fruits with high antioxidant capacities. Despite this, several of these species are yet to be tested for anticancer activity.

MATERIALS AND METHODS

Solvent extracts prepared from high antioxidant native Australian fruits were analyzed for antioxidant capacity by the di (phenyl)-(2,4,6-trinitrophenyl) iminoazanium free radical scavenging assay. Antiproliferative activities against CaCo2 and HeLa cancer cells were determined by a multicellular tumor spheroid-based cell proliferation assay. Toxicity was determined by Artemia franciscana bioassay.

RESULTS

Methanolic extracts of all plant species displayed high antioxidant contents (equivalent to approximately 7-16 mg of vitamin C per gram of fruit extracted). Most aqueous extracts also contained relatively high antioxidant capacities. In contrast, the ethyl acetate, chloroform, and hexane extracts of most species (except lemon aspen and bush tomato) had lower antioxidant contents (below 1.5 mg of vitamin C equivalents per gram of plant material extracted). The antioxidant contents correlated with the ability of the extracts to inhibit proliferation of CaCo2 and HeLa cancer cell lines. The high antioxidant methanolic extracts of all species were potent inhibitors of cell proliferation. The methanolic lemon aspen extract was particularly effective, with IC50 values of 480 and 769 μg/mL against HeLa and CaCo2 cells, respectively. In contrast, the lower antioxidant ethyl acetate and hexane extracts (except the lemon aspen ethyl acetate extract) generally did not inhibit cancer cell proliferation or inhibited to only a minor degree. Indeed, most of the ethyl acetate and hexane extracts induced potent cell proliferation. The native tamarind ethyl acetate extract displayed low-moderate toxicity in the A. franciscana bioassay (LC50 values below 1000 μg/mL). All other extracts were nontoxic. A total of 145 unique mass signals were detected in the lemon aspen methanolic and aqueous extracts by nonbiased high-performance liquid chromatography-mass spectrometry analysis. Of these, 20 compounds were identified as being of particular interest due to their reported antioxidant and/or anticancer activities.

CONCLUSIONS

The lack of toxicity and antiproliferative activity of the high antioxidant plant extracts against HeLa and CaCo2 cancer cell lines indicates their potential in the treatment and prevention of some cancers.

SUMMARY

Australian fruit extracts with high antioxidant contents were potent inhibitors of CaCo2 and HeLa carcinoma cell proliferationMethanolic lemon aspen extract was particularly potent, with IC50 values of 480 μg/mL (HeLa) and 769 μg/mL (CaCo2)High-performance liquid chromatography-mass spectrometry-quadrupole time-of-flight analysis highlighted and putatively identified 20 compounds in the antiproliferative lemon aspen extractsIn contrast, lower antioxidant content extracts stimulated carcinoma cell proliferationAll extracts with antiproliferative activity were nontoxic in the Artemia nauplii assay. Abbreviations used: DPPH: di (phenyl)- (2,4,6-trinitrophenyl) iminoazanium, HPLC: High-performance liquid chromatography, IC50: The concentration required to inhibit by 50%, LC50: The concentration required to achieve 50% mortality, MS: Mass spectrometry.

A Review of the Benefits of Satureja Species on Metabolic Syndrome and Their Possible Mechanisms of Action

Metabolic syndrome, also known as insulin resistance disorder, is the simultaneous manifestation of multiple metabolic disorders in an individual. The present-day complementary and alternative therapies suggest several medicinal herbs that may have the potential to improve one or multiple complications of metabolic syndrome. All of them have their own limitations in efficacy and unwanted effects. Therefore, we reviewed species of Satureja as widespread medicinal herbs and potentially good remedies for metabolic syndrome. We reviewed literature found in PubMed and the ISI Web of Knowledge with the key word Satureja in the title. The influence of any species of Satureja on any disease or syndrome, enzymatic, metabolic, or physiological pathways, in human, animals, or in vitro conditions related to any characteristics of metabolic syndrome were considered. The main outcomes of treatment with Satureja species were categorized, and the possible mechanisms of action are discussed in this article.

Addition of vardenafil into storage solution protects the endothelium in a hypoxia-reoxygenation model

OBJECTIVE

Based upon the well known protective effect of intracellular cyclic guanosine monophosphate (cGMP) accumulation, we tested the hypothesis that storage solution enriched with optimal concentration of the phosphodiestherase-5 inhibitor vardenafil could provide better protection of vascular grafts against reperfusion injury after long-term cold ischaemic storage.

METHODS

Isolated thoracic aorta obtained from rats underwent 24-h cold ischaemic preservation in physiological saline or vardenafil (10(-11) M)-supplemented saline solution. Reperfusion injury was simulated by hypochlorite (200 μM) exposure for 30 minutes. Endothelium-dependent vasorelaxation was assessed, and histopathological and molecular-biological examination of the aortic tissue were performed.

RESULTS

Compared with the control group, the saline group showed significantly attenuated endothelium-dependent maximal relaxation (Rmax) to acetylcholine after hypoxia-reoxygenation, which was significantly improved by vardenafil supplementation (Rmax control: 98 ± 1%; saline: 48 ± 6%; vardenafil: 75 ± 4%; p < .05). Vardenafil treatment significantly reduced DNA strand breaks (control: 10.6 ± 6.2%; saline: 72.5 ± 4.0%; vardenafil: 14.2 ± 5.2%; p < .05) and increased cGMP score in the aortic wall (control: 8.2 ± 0.6; saline: 4.5 ± 0.3; vardenafil: 6.7 ± 0.6; p < .05).

CONCLUSIONS

Our results support the view that impairment of intracellular cGMP signalling plays a role in the pathogenesis of the endothelial dysfunction induced by cold storage warm reperfusion, which can be effectively reversed by pharmacological phosphodiesterase-5 inhibition.

Vascular dysfunction induced by hypochlorite is improved by the selective phosphodiesterase-5-inhibitor vardenafil

Reactive oxygen species, such as hypochlorite induce oxidative stress, which impairs nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) signalling and leads to vascular dysfunction. It has been proposed, that elevated cGMP-levels may contribute to an effective cytoprotection against oxidative stress. We investigated the effects of vardenafil, a selective inhibitor of the cGMP-degrading phosphodiesterase-5 enzyme on vascular dysfunction induced by hypochlorite. In organ bath experiments for isometric tension, we investigated the endothelium-dependent and endothelium-independent vasorelaxation of isolated rat aortic rings using cumulative concentrations of acetylcholine and sodium nitroprusside (SNP). Vascular dysfunction was induced by exposing rings to hypochlorite (100-400 µM). In the treatment groups, rats were pretreated with vardenafil (30 and 300 µg/kg i.v.). Immunohistochemical analysis was performed for the oxidative stress markers nitrotyrosine, poly(ADP-ribose) and for apoptosis inducing factor (AIF). Exposure to hypochlorite resulted in a marked impairment of acetylcholine-induced endothelium-dependent vasorelaxation of aortic rings. Pretreatment with vardenafil led to improved endothelial function as reflected by the higher maximal vasorelaxation (Rmax) to acetylcholine. Regarding endothelium-independent vasorelaxation, hypochlorite exposure led to a left-shift of SNP concentration-response curves in the vardenafil groups without any alterations of the Rmax. In the hypochlorite groups immunohistochemical analysis showed enhanced poly(ADP-ribose)-formation and nuclear translocation of AIF, which were prevented by vardenafil-pretreatment. Our results support the view that cytoprotective effects of PDE-5-inhibitors on the endothelium may underlie the improved endothelial function, however, a slight sensitisation of vascular smooth muscle to NO was also confirmed. PDE-5-inhibition may represent a potential therapy approach for treating vascular dysfunction induced by oxidative stress.

Beneficial effect of phosphodiesterase-5 inhibitor in experimental inflammatory bowel disease; molecular evidence for involvement of oxidative stress

ABSTRACT Inflammatory bowel disease (IBD) is a common and chronic gastrointestinal disorder characterized by intestinal inflammation and mucosal tissue damage. Reactive oxygen metabolites (ROMs) play a pathogenic role in IBD. We aimed to examine the protective effect of sildenafil, a cGMP phosphodiesterase inhibitor, in the experimental mouse model of IBD. Intrarectal instillation of acetic acid was used to induce IBD. Prednisolone was used as the standard drug for comparison. Sildenafil was used at doses of 0.75, 1.5, and 3 mg/kg. Biochemicals and macroscopic and microscopic examinations of colonic tissue were performed. Results indicated that activity of myeloperoxidase (MPO) and lipid peroxidation product (TBARS) markers of oxidative stress are increased in acetic acid-treated groups and are recovered by sildenafil pretreatment and prednisolone. Sildenafil- (1.5 and 3 mg/kg) and prednisolone-treated groups showed significantly lower score values of macroscopic and microscopic characters when compared to the acetic acid-treated group. The beneficial effect of sildenafil (3 mg/kg) was comparable to that of prednisolone. It is concluded that sildenafil is helpful in the management of IBD, which is presumably related to its strong antioxidative stress potential mediated through enhanced cGMP. Results of proper clinical trials will determine the possible efficacy of phosphodiesterase-5 inhibitors in human IBD.

Biochemical and histopathological evidences for beneficial effects of satureja khuzestanica jamzad essential oil on the mouse model of inflammatory bowel diseases

The essential oil from Satureja Khuzestanica Jamzad (SKEO), an endemic plant from Iran, was evaluated for its activity against inflammatory bowel disease (IBD). SKEO was examined on the experimental mouse model of inflammatory bowel disease, which is acetic acid-induced colitis. Prednisolone was used as the standard drug for comparison. Biochemical, macroscopic, and microscopic examinations of colon were performed. Lipid peroxidation significantly increased in acetic acid-treated mice in comparison to the normal group (4.88 vs. 3.02 mumol/g) and was significantly restored by SKEO (500, 1000, 1500 ppm) and prednisolone treatment. The mean percentage of decreases of lipid peroxidation in SKEO (500, 1000, 1500 ppm)- and prednisolone-treated groups were 10.5, 28.5, 42.85, and 33.33 of control, respectively. The myeloperoxidase activity significantly increased in acetic acid-treated mice in comparison to the normal group (4.1 vs. 0.8 U/g) and significantly restored in SKEO (1000 and 1500 ppm)- and prednisolone-treated groups. The mean percentage of decreases of myeloperoxidase activity in SKEO (1000 and 1500 ppm)- and prednisolone-treated groups were 24.56, 50, and 52.63 of control, respectively. SKEO (1000 and 1500 ppm)- and prednisolone-treated groups showed significantly lower score values of macroscopic and microscopic characters when compared to the acetic acid-treated group. The beneficial effect of SKEO (1500 ppm) was comparable to that of prednisolone. Known antioxidant, antimicrobial, antiinflammatory, and antispasmodic potentials of Satureja Khuzestanica may be the mechanisms by which this plant protects animals against experimentally induced IBD. Proper clinical investigation should be carried out to confirm the activity in human disease.

Effects of protein kinase A and G inhibitors on hippocampal cholinergic markers expressions in rolipram- and sildenafil-induced spatial memory improvement

Although there are number of studies showing that phosphodiesterase (PDE) 4 and 5 inhibitors affect different kinds of memory, their effects on spatial memory consolidation in conjunction with the cholinergic activity in the hippocampus have not been studied before. In the present study firstly, rats were evaluated for the effects of different doses of the PDE4 inhibitor rolipram and the PDE5 inhibitor sildenafil on spatial memory consolidation in the water maze task. Rolipram or sildenafil was daily administered intraperitoneally 3 or 0 h after the last trial of training, respectively. Then in a separate related experiment the effect of the most efficient doses of rolipram or sildenafil accompanied by an intrahippocampally injected protein kinase A (PKA) or protein kinase G (PKG) inhibitor, respectively, was examined. Finally for determination of the hippocampal cholinergic activity the protein expression of hippocampal vesicular acetylcholine transporter (VAChT) and cholineacetyltransferase (ChAT) was measured. Rolipram at 0.03 mg/kg as well as sildenafil at 3 mg/kg increased spatial memory and their enhancing effect was completely blocked following inhibition of PKA and PKG, respectively. Furthermore, none of the treatments had a significant effect on the hippocampal ChAT and VAChT levels. Our data showed that rolipram and sildenafil enhanced spatial memory consolidation in an inverted U-shaped dose-response curve. This effect is dependent on the activity of cAMP/PKA- and cGMP/PKG-mediated pathways, respectively in the hippocampus. However, we did not find evidence for a chronic increase of cholinergic activity in the observed PDE inhibitor-induced memory improvement.

Update on the clinical utility of sildenafil in the treatment of pulmonary arterial hypertension

Sildenafil is an orally administered phosphodiesterase type 5 inhibitor that is approved for the treatment of pulmonary arterial hypertension (PAH). The hemodynamic effects of sildenafil are mitigated primarily via potentiating the effects of endogenous nitric oxide, leading to smooth muscle cell relaxation and reductions in pulmonary arterial pressures and pulmonary vascular resistance. When added to standard background therapy in patients with idiopathic or associated PAH from congenital heart disease, anorexigen use, or connective tissue disease, sildenafil treatment results in improved exercise capacity as measured by 6 minute walk distance, improved hemodynamics, and favorable changes in quality of life. Sildenafil use is contraindicated with concomitant nitrate administration, and caution should be exercised when used in combination with antihypertensive agents due to risks of precipitating hypotension. Side effects are generally mild, and include flushing, headaches, and epistaxis. The combination of sildenafil with intravenous epoprostenol is safe and well tolerated, and further improves exercise capacity. Sildenafil is approved only for treatment of PAH, and although emerging data suggest a potential role in treating other types of pulmonary hypertension, larger trials are required to confirm these findings.

Sildenafil decreased cardiac cell apoptosis in diabetic mice: reduction of oxidative stress as a possible mechanism

Oxidative stress plays a dominant role in the pathogenesis of cardiac cell apoptosis in diabetic patients. Sildenafil has been demonstrated to have antioxidant effects. In this study, the effects of sildenafil on diabetes-induced cardiac cell apoptosis and the antioxidant status of diabetic mouse hearts were investigated. Diabetic mice showed lower body weight gains and heart weights compared with control mice, and sildenafil treatment did not increase these parameters in diabetic mice. Although apoptotic rates, caspase-3 enzyme activity, and malondialdehyde levels were significantly higher in diabetic mouse hearts than in controls, they were reduced in diabetic mice after sildenafil treatment. At the end of the first week, we observed no significant differences in antioxidant enzyme activities (CAT, GSH-Px, and SOD) in diabetic and control groups, whereas at the end of the second week of sildenafil treatment, antioxidant enzyme activities were higher in the diabetic group. In conclusion, our study indicated that sildenafil was beneficial to hearts of diabetic mice by reducing cardiac cell apoptosis, partially because of its antioxidant effects in the heart.

Study on clinical and biochemical toxicity biomarkers in a zinc-lead mine workers

The aim of this study was to determine oxidative stress status as well as blood lead (Pb) and zinc (Zn) levels and clinical markers in workers of a Zn-Pb mine. A comparative cross-sectional analysis was performed in 67 mine workers who have been in contact with Zn and Pb in comparison to a control group containing 67 healthy subjects with the same age and sex. Lipid peroxidation, superoxide dismutase, catalase, glutathione reductase, myleoperoxidase, DNA damage, total antioxidant capacity, Zn, and Pb levels were measured in blood of workers and controls. Clinical examination was accomplished to record any abnormal sign or symptoms. Comparing with controls, the workers showed higher blood levels of superoxide dismutase, myleoperoxidase, glutathione reductase, lipid peroxidation, Pb, and Zn. Workers showed lower DNA-damage as compared with controls. Workers showed clinical symptoms such as memory impairment, less of concentration, insomnia, headache, claudication, epigasteric, inappetence, agitation, tremor, decreasing of reflection of deep tendon, conduction deafness of ear, and fatigue. The workers had extra normal levels of Pb (0.9-3 microg/dL) and showed oxidative stress. Taken together, the results indicate that exposure to combination of Pb and Zn in mine elevates total antioxidant capacity of body in a reflex to overcome to oxidative stress. Especially, in the present case, it seems that toxic effect of Pb has been greater than positive effects of Zn, but the combination exposure has resulted in not such a critical toxicity situation.

On the benefit of Teucrium in murine colitis through improvement of toxic inflammatory mediators

Regarding the role of free radicals in pathogenesis of inflammatory bowel disease (IBD), we were interested to investigate the effects of Teucrium persicum with approved antioxidant and anti-inflammatory properties in an experimental model of colitis. Immunologic colitis was induced by rectal administration of a mixture of 2,4,6-trinitrobenzene sulphonic acid (TNBS) and ethanol through rubber cannula into rats. Three different doses of Teucrium (100, 200, and 400 mg/kg) were gavaged in a duration of 10 days to rats. Endpoint markers of colitis included macroscopic and microscopic examination of colon tissue and measuring colonic cells concentrations of tumor necrosis factor-alpha (TNF-alpha), interlukin-1beta (IL-1beta), total antioxidant power as ferric reducing antioxidant power (FRAP), myeloperoxidase (MPO), and lipid peroxidation as thiobarbitoric acid-reactive substance (TBARS). Teucrium at all doses improved both macroscopic and histological damages of rats with colitis. Teucrium reduced colonic MPO activity and concentrations of cellular lipid peroxides, TNF-alpha, and IL-1beta, with a concomitant increase in FRAP value in rats with colitis. It is concluded that beneficial effects of Teucrium in experimental colitis is mediated through its antioxidant and anti-inflammatory potentials. Examination of this herbal medicine in patients with IBD as a supplement would further reveal the potential of Teucrium.

A review of the herbal phosphodiesterase inhibitors; future perspective of new drugs

Phosphodiesterase inhibitors (PDEIs) are a class of drugs that are widely used because of their various pharmacological properties including cardiotonic, vasodilator, smooth muscle relaxant, antidepressant, antithrombotic, bronchodilator, antiinflammatory and enhancer of cognitive function. In the recent years, interest in drugs of plant origin has been progressively increased. Some pharmacologically active substances that come from plants demonstrate PDEI activity. They mainly belong to alkaloids, flavonoids, and saponins. In this review, studies on herbal PDEI were reviewed and their possible therapeutic applications were discussed. Screening plants for PDE inhibitory activity may help to develop standardized phytotherapeutic products or find new sources for new lead structures with PDEI pharmacological activity. The studies discussed in this paper are mainly in vitro and for more reasonable and conclusive results, it is required to conduct in vivo and finally human and clinical tests.

Inhibition of tumor necrosis factor and nitrosative/oxidative stresses by Ziziphora clinopoides (Kahlioti); a molecular mechanism of protection against dextran sodium sulfate-induced colitis in mice

Inflammatory bowel disease (IBD) is a chronic condition of the intestine with unknown etiology involving multiple immune genetic and environmental factors. The authors were interested in examining the protective effect of Ziziphora clinopoides methanolic extract, an Iranian folk herbal medicine, on inflammatory mediators in experimental colitis. Colitis in NMRI mice was induced by oral administration of dextran sodium sulfate (DSS, 3%). Z. clinopoides was administrated orally at doses of 75, 150, and 300 mg/kg/day for 7 days. The level of lipid peroxidation (LP), total antioxidant capacity (TAC), total thiol molecules (TTM), antioxidant enzymes including superoxide dismutase (SOD) and catalase (CAT), and nitric oxide (NO) as a marker of nitrosative stress, and tumor necrosis factor alpha (TNF-alpha) as a mediator of inflammation and apoptosis were measured in the colon homogenate. Treatment by DSS increased bowel LP, NO, and TNF-alpha while decreasing TAC, SOD, CAT, and TTM. All measured parameters were improved by Z. clinopoides treatment and reached close to normal levels. The present study further supports the role of oxidative/nitrosative stresses and TNF-alpha in the pathogenesis of colitis and protective effects of this herb. The data are promising for further preclinical studies directed towards understanding mechanism of action and cross-species and cross-model comparisons for potential protective effects.

Cumulative lead exposure and tooth loss in men: the normative aging study

BACKGROUND

Individuals previously exposed to lead remain at risk because of endogenous release of lead stored in their skeletal compartments. However, it is not known if long-term cumulative lead exposure is a risk factor for tooth loss.

OBJECTIVES

We examined the association of bone lead concentrations with loss of natural teeth.

METHODS

We examined 333 men enrolled in the Veterans Affairs Normative Aging Study. We used a validated K-shell X-ray fluorescence (KXRF) method to measure lead concentrations in the tibial midshaft and patella. A dentist recorded the number of teeth remaining, and tooth loss was categorized as 0, 1-8 or > or = 9 missing teeth. We used proportional odds models to estimate the association of bone lead biomarkers with tooth loss, adjusting for age, smoking, diabetes, and other putative confounders.

RESULTS

Participants with > or = 9 missing teeth had significantly higher bone lead concentrations than those who had not experienced tooth loss. In multivariable-adjusted analyses, men in the highest tertile of tibia lead (> 23 microg/g) and patella lead (> 36 microg/g) had approximately three times the odds of having experienced an elevated degree of tooth loss (> or = 9 vs. 0-8 missing teeth or > or = 1 vs. 0 missing teeth) as those in the lowest tertile [prevalence odds ratio (OR) = 3.03; 95% confidence interval (CI), 1.60-5.76 and OR = 2.41; 95% CI, 1.30-4.49, respectively]. Associations between bone lead biomarkers and tooth loss were similar in magnitude to the increased odds observed in participants who were current smokers.

CONCLUSION

Long-term cumulative lead exposure is associated with increased odds of tooth loss.

Improvement of inflammatory and toxic stress biomarkers by silymarin in a murine model of type one diabetes mellitus

Type 1 diabetes mellitus (T1DM) is characterized by an impairment of the insulin-secreting beta cells with an immunologic base. Inflammatory cytokines such as tumor necrosis factor (TNF)-α and interleukin (IL)-1β, and free radicals are believed to play key roles in destruction of pancreatic β cells. The present study was designed to investigate the effect of Silybum marianum seed extract (silymarin), a combination of several flavonolignans with immunomodulatory, anti-oxidant, and anti-inflammatory potential on streptozotocin (STZ)-induced T1DM in mouse. Experimental T1DM was induced in male albino mice by IV injection of multiplelow- doses of STZ for 5 days. Seventy-two male mice in separate groups received various doses of silymarin (20, 40, and 80 mg/kg) concomitant or after induction of diabetes for 21 days. Blood glucose and pancreatic biomarkers of inflammation and toxic stress (IL-1β, TNF-α, myeloperoxidase, lipid peroxidation, protein oxidation, thiol molecules, and total antioxidant capacity) were determined. Silymarin treatment reduced levels of inflammatory cytokines such as TNF-α and IL-1β and oxidative stress mediators like myeloperoxidase activity, lipid peroxidation, carbonyl and thiol content of pancreatic tissue in an almost dose dependent manner. No marked difference between the prevention of T1DM and the reversion of this disease by silymarin was found. Use of silymarin seems to be helpful in T1DM when used as pretreatment or treatment. Benefit of silymarin in human T1DM remains to be elucidated by clinical trials.

Benefit of Satureja khuzestanica in subchronically rat model of cyclophosphamide-induced hemorrhagic cystitis

Cyclophosphamide (CP) as a widely used antineoplastic drug causes hemorrhagic cystitis (HC) mainly via induction of oxidative stress. Regarding established antioxidant potential of Satureja khuzestanica (Lamiaceae) essential oil (SKEO), we aimed to investigate its protective effects in a subchronic rat model of CP-induced HC. CP (6mg/kg/day) and SKEO (225mg/kg/day) were administered alone or in combination by gavage for 28 days. Histopathological changes were investigated by light microscopy. Plasma samples were assayed for lipid peroxidation and total antioxidant power as biomarkers of toxic stress. In the CP-treated animals, irregular mucus layer, severe hemorrhage and edema, infiltration of inflammatory cells, and accumulation of mast cells were observed. In the CP+SKEO group, a relatively normal urothelial topography with decreased number of mucosal mast cells and inflammatory cells were observed. Increased lipid peroxidation along with decreased total antioxidant capacity resulting from CP treatment was significantly recovered by SKEO co-treatment. It is concluded that SKEO protects rats from CP-induced HC by reduction of free radical-induced toxic stress. It is strongly recommended to examine SKEO in the clinic to approve its benefit in patients undertaking CP.

Sildenafil citrate as a phosphodiesterase inhibitor has an antioxidant effect in the blood of men

BACKGROUND AND OBJECTIVE

Sildenafil citrate enhances the action of nitric oxide by preventing the hydrolysis of cGMP, and is widely used to treat erectile dysfunction. We investigated the effects of sildenafil citrate administration on lipid peroxidation and antioxidant redox enzymes in blood of healthy men.

METHOD

Thirty healthy male subjects were divided equally into two groups. The first group was used as the control. A single dose of sildenafil citrate was administrated orally to subjects constituting the second group. Blood samples were obtained at 0, 2, 6 and 24 h after intake of the single dose of 100 mg sildenafil citrate or placebo.

RESULTS AND DISCUSSION

The dose of sildenafil citrate resulted in significant increase in the erythrocyte superoxide dismutase and catalase activities at 6 and 24 h. Plasma lipid peroxidation levels decreased slightly. There was no statistical difference in erythrocyte glutathione peroxidase activity between the placebo and sildenafil citrate groups.

CONCLUSION

Treatment of blood with 100 mg sildenafil citrate has protective effects on oxidative stress by inhibiting free radical formation and by supporting antioxidant redox systems.

The phosphodiesterase-5 inhibitor vardenafil improves cardiovascular dysfunction in experimental diabetes mellitus

BACKGROUND AND PURPOSE

Patients with diabetes mellitus exhibit generalized endothelial and cardiac dysfunction with decreased nitric oxide production. Elevated intracellular cyclic guanosine monophosphate (cGMP) levels contribute to an effective cardioprotection in different pathophysiological conditions. In this study, we investigated whether chronic treatment with the phosphodiesterase-5 inhibitor vardenafil could improve diabetic cardiovascular dysfunction by up-regulating the nitric oxide-cGMP pathway in the vessel wall and myocardium.

EXPERIMENTAL APPROACH

Diabetes was induced in young rats by a single intraperitoneal injection of streptozotocin (60 mg x kg(-1)). In the treatment group, vardenafil (10 mg x kg(-1) x day(-1)) was given orally for 8 weeks. Diabetic control animals received vehicle for the same time. Left ventricular pressure-volume relations were measured by using a microtip Millar pressure-volume conductance catheter, and indexes of contractility, such as the slope of end-systolic pressure-volume relationship (E(max)) and preload recruitable stroke work (PRSW), were calculated. In organ bath experiments for isometric tension with rings of isolated aortae, endothelium-dependent and independent vasorelaxation was investigated by using acetylcholine and sodium nitroprusside.

KEY RESULTS

When compared with the non-diabetic controls, diabetic rats showed increased myocardial and vascular transforming growth factor-beta1 expression, impaired left ventricular contractility (impairment of E(max) by 53%, PRSW by 40%; P < 0.05) and vascular dysfunction. Treatment with vardenafil resulted in higher cGMP levels, reduced transforming growth factor-beta1 expression, significantly improved cardiac function (improvement of E(max) by 95%, PRSW by 69%; P < 0.05) and greater vasorelaxation to acetylcholine and sodium nitroprusside in aortae from diabetic animals.

CONCLUSIONS AND IMPLICATIONS

Our results demonstrate that impaired vascular cGMP signalling contributes to the development of diabetic vascular and cardiac dysfunction, which can be prevented by chronic phosphodiesterase-5 inhibition.

Effects of selective phosphodiesterase-5-inhibition on myocardial contractility and reperfusion injury after heart transplantation

Recently, the infarct reducing and cardioprotective effects of phosphodiesterase-5-inhibitors were described. In this study, we investigated these effects on ischemia/reperfusion injury in a rat model of heart transplantation. Three groups were assigned for our study: a vardenafil preconditioning group, an ischemic control, and a nonischemic control. Hemodynamic parameters were significantly increased in the vardenafil group (Pmax: 82+/-4 vs. 110+/-12 vs. 127+/-13 mm Hg; dP/dtmax: 1740+/-116 vs. 3197+/-599 vs. 4397+/-602 mm Hg/sec; ischemic control vs. vardenafil vs. nonischemic control; P<0.05 vs. ischemic control). Furthermore, we recorded increased ATP levels and significantly less apoptosis in the treatment group after terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (apoptosis index: 27.23%+/-1.54% vs. 16.77%+/-1.42% vs. 18.86%+/-1.07%; ischemic control vs. vardenafil vs. nonischemic control; P<0.05 vs. ischemic control). Our current results support the concept that the cGMP-PKG-pathway plays an important role in ischemia/reperfusion injury. We could show that up-regulating this pathway has a preconditioning-like effect and can effectively reduce ischemia/reperfusion injury.

Benefits of Zataria multiflora Boiss in Experimental Model of Mouse Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a chronic condition of the intestine with unknown etiology involving multiple immune, genetic and environmental factors. We were interested to examine the effect of total extract from Zataria multiflora Boiss, a folk medicinal plant on prevention and treatment of experimental IBD. Z. multiflora was administered (400, 600, 900 p.p.m.) through drinking water to IBD mice induced by intrarectal administration of acetic acid. Prednisolone was used as the standard drug for comparison. Biochemical, macroscopic and microscopic examinations of colon were performed. Biochemical evaluation of inflamed colon was done using assay of myeloperoxidase (MPO) activity and thiobarbituric acid reactive substances (TBARS) concentration as indicators of free radical activity and cell lipid peroxidation. The activity of MPO and lipid peroxidation products (TBARS) increased in acetic acid-treated groups while recovered by pretreatment of animals with Z. multiflora (400–900 p.p.m.) and prednisolone. Z. multiflora (600 and 900 p.p.m.) and prednisolone-treated groups showed significantly lower score values of macroscopic and microscopic characters when compared with the acetic acid-treated group. The beneficial effect of Z. multiflora (900 p.p.m.) was comparable with that of prednisolone. The antioxidant, antimicrobial and anti-inflammatory potentials of Z. multiflora might be the mechanisms by which this herbal extract protects animals against experimentally induced IBD. Proper clinical investigation should be carried out to confirm the activity in human.

Protection by Ziziphora clinopoides of acetic acid-induced toxic bowel inflammation through reduction of cellular lipid peroxidation and myeloperoxidase activity

Inflammatory bowel disease (IBD) is a chronic condition of the intestine with unknown etiology involving multiple immune, genetic and environmental factors. We were interested in examining the effect of a total extract from Ziziphora clinopoides, an Iranian folk herbal medicine, in the prevention and control of experimental mouse IBD. Z. clinopoides was administered (75, 150, 300 mg/kg) through drinking water to mice, which dispensed a toxic dose of acetic acid intrarectally. Prednisolone was used as the standard drug for comparison. Biochemical, macroscopic and microscopic examinations of the colon were performed. Biochemical evaluation of the inflamed colon was carried out using assays of myeloperoxidase (MPO) activity and thiobarbituric acid reacting substances (TBARS) as indicators of free radical activity and cellular lipid peroxidation. Results indicated that the activity of MPO and lipid peroxidation products (TBARS) increased in acetic acid-treated groups, while recovered by pretreatment of animals with Z. clinopoides (75-300 mg/kg) and prednisolone. All doses of Z. clinopoides and prednisolone-treated groups showed significant lower score values of macroscopic and microscopic characters when compared to the acetic acid-treated group. The beneficial effect of Z. clinopoides (300 mg/kg) was comparable to that of prednisolone. It is concluded that Z. clinopoides inhibits acetic acid toxic reactions in the mouse bowel through inhibition of cellular oxidative stress. Proper clinical investigation should be carried out to confirm the same activity in human.

Lipids, lipid peroxidation and 7-ketocholesterol in workers exposed to lead

The study population included healthy men and hypertensive employees of zinc and lead steelworks in the south of Poland. Workers exposed to lead (n=137) were divided into two groups: the first included employees with low exposure to lead (LL) with mean blood lead (PbB) 25-40 microg/dL and the second one with PbB over 40 microg/dL (HL group). The administration workers (n=35) were the control group. Evaluation of lipids and oxidative changes of cholesterol and lipids were estimated in blood samples. No significant changes in concentration of 7-ketocholesterol and blood lipids (cholesterol, HDL, LDL, triglycerides) were found. Lipid peroxidation (LP) was significantly higher in both exposed groups in plasma and in the HL group in erythrocytes when compared with control. There can be two independent sources of LP increase: the first is connected with the direct effect of lead's ions on erythrocytes, the second is the prooxidative effect of delta-aminolevulinic acid. Hypertension in the HL group when compared with people with PbB below 40 microg/dL (OR 4.4, 95%CI 1.4-14.5) was found more often. LP significantly increased by about 71% and concentration of 7-ketocholesterol by about 122% in hypertensives when compared with normotensives in the HL group.

Comparison of the effects of melatonin and pentoxifylline on carbon tetrachloride-induced liver toxicity in mice

The purpose of the study was to determine whether along and in combination melatonin (MLT) and pentoxifylline (PTX) exerted beneficial effects on histopathological changes and changes in oxidant and antioxidant systems in liver caused by CCl4-induced liver toxicity in mice. Mice were randomly divided into six groups: control, olive oil, toxicity, MLT, PTX, PTX+MLT. MLT 10 mg/kg/day, PTX 50 mg/kg/day, and the same individual doses in MLT+PTX combination were given intraperitoneally to mice for 7 day. CCl4 0.8 mg/kg/day was administered on the 4th, 5th, and 6th days of therapy in all groups except the control and olive oil groups. In the toxicity group, increased concentrations of malondialdehyde (MDA) and lipid hydroperoxides (LOOH) and decreased glutathione peroxidase (GSH-Px) and catalase (CAT) activities were found compared to the control and olive oil groups (p < 0.05). Compared to the toxicity group, both the PTX group and the PTX+MLT group had decreased MDA and LOOH levels, whereas MLT reduced only LOOH levels (p < 0.01). MLT, PTX and MLT+PTX increased the GSH-Px and CAT activities compared to the toxicity group (p < 0.05). MLT increased CAT activity compared to PTX and MLT+PTX (p < 0.05). Superoxide dismutase enzyme activity did not change in any group (p < 0.05). Histopathologically, ballooning, degeneration, apoptosis, and bridging necrosis were seen in the toxicity group. MLT, PTX and MLT+PTX decreased the apoptosis and bridging necrosis (p < 0.01), and PTX and MLT+PTX decreased balloon degeneration compared to the toxicity group (p < 0.01). These results indicate that administration of PTX and MLT alone and in combination before onset of liver toxicity might prevent the oxidative damage by reducing oxidative stress and increasing antioxidant enzyme levels.

A review on the role of antioxidants in the management of diabetes and its complications

Diabetes is a prevalent systemic disease affecting a significant proportion of the population worldwide. The effects of diabetes are devastating and well documented. There is increasing evidence that in certain pathologic states, especially chronic diseases, the increased production and/or ineffective scavenging of reactive oxygen species (ROS) may play a critical role. High reactivity of ROS determines chemical changes in virtually all cellular components, leading to lipid peroxidation. Production of ROS and disturbed capacity of antioxidant defense in diabetic subjects have been reported. It has been suggested that enhanced production of free radicals and oxidative stress is central event to the development of diabetic complications. This suggestion has been supported by demonstration of increased levels of indicators of oxidative stress in diabetic individuals suffering from complications. Therefore, it seems reasonable that antioxidants can play an important role in the improvement of diabetes. There are many reports on effects of antioxidants in the management of diabetes. In this paper, after complete bibliography and criticizing all relevant articles, the relationships between diabetes and oxidative stress and use of antioxidants in the management of diabetes and its complications have been well reviewed. This review well indicates that oxidative stress is involved in the pathogenesis of diabetes and its complications. Use of antioxidants reduces oxidative stress and alleviates diabetic complications.

Hemodynamic effects of combined sildenafil and L-arginine during acute pulmonary embolism-induced pulmonary hypertension

Sildenafil attenuates acute pulmonary embolism-induced pulmonary hypertension. However, the hemodynamic effects of sildenafil in combination with other vasodilators during acute pulmonary embolism have not been examined yet. In the present study, we examined the hemodynamic effects of combined sildenafil (0.25 mg/kg, i.v.) and L-arginine (100, 200, 500, and 1000 mg/kg/h, i.v.) in an anesthetized dog model of acute pulmonary embolism. Plasma nitrite/nitrate (NO(x)) and cGMP concentrations were determined using an ozone-based chemiluminescence assay and a commercial enzyme immunoassay, respectively. We found that L-arginine alone did not attenuate acute pulmonary embolism-induced pulmonary hypertension. However, significant decreases in mean pulmonary artery pressure were observed 30, 45, 60, and 75 min after the administration of sildenafil alone or after the combined administration of sildenafil and L-arginine (all P < 0.05). No significant differences among groups were observed in the respiratory parameters. While L-arginine significantly increased NO(x) concentrations, cGMP concentrations increased only when sildenafil was administered (all P < 0.05). These results suggest that while sildenafil attenuates acute pulmonary embolism-induced pulmonary hypertension, L-arginine does not enhance the beneficial hemodynamic effects of sildenafil. In addition, these findings suggest that stimulation of NO synthesis with L-arginine during acute pulmonary embolism does not produce beneficial effects.

Total antioxidant capacity and levels of epidermal growth factor and nitric oxide in blood and saliva of insulin-dependent diabetic patients

BACKGROUND

The aim of this study was to examine how type 1 diabetic patients have altered levels of lipid peroxidation, antioxidant defense, NO and EGF in their plasma and saliva. We tested the differences in lipid peroxidation level, antioxidant power, and concentrations of epidermal growth factor (EGF) and nitric oxide (NO) in saliva and blood of type 1 diabetic subjects in comparison to healthy control subjects.

METHODS

Nineteen subjects with type 1 diabetes mellitus and 19 healthy age- and sex-matched control subjects were included in the study. Blood and saliva samples were obtained and analyzed for thiobarbituric reactive substances (TBARS) as a marker of lipid peroxidation, ferric reducing ability (total antioxidant power), EGF and NO levels.

RESULTS

TBARS levels did not show a significant difference between the two groups. Analysis of antioxidant power revealed that saliva and plasma of diabetic patients had more antioxidant power (p <0.01) than the healthy control population (107 +/- 10.35 vs. 11.14 +/- 4.66 and 192 +/- 12.3 vs. 142 +/- 15.2 mmol/L, respectively). Concentration of EGF was increased (p <0.01) in saliva whereas it was reduced (p <0.01) in plasma of diabetic patients in comparison to those of healthy subjects (2423 +/- 322 vs. 1513 +/- 341 and 125 +/- 14 vs. 346 +/- 60 pg/mL, respectively). NO level increased in both saliva and plasma of diabetic patients in comparison to those of healthy subjects (46.61 +/- 7 vs. 72.89 +/- 13 and 62.11 +/- 4.6 vs. 76.25 +/- 5 micromol/L, respectively). Blood HbA1c (%) of patients was significantly higher than that of controls (8.3 +/- 0.32 vs. 5.4 +/- 0.24, p <0.01).

CONCLUSIONS

Existence of increased total antioxidant power in the presence of normal lipid peroxidation in plasma and saliva of type 1 diabetic patients indicates the existence of oxidative stress. Increased salivary EGF and NO levels in association with elevated TAOP is interesting and should be further studied.

Effects of pentoxifylline on oxidative stress and levels of EGF and NO in blood of diabetic type-2 patients; a randomized, double-blind placebo-controlled clinical trial

BACKGROUND

As oxidative stress contributes to both progression and pathologic complications of diabetes and effective therapeutic strategies to prevent or delay the damage remain limited, the aim of the present study was to assess the efficacy of pentoxifylline in reducing of oxidative stress. Since there is a relationship between nitric oxide (NO), epidermal growth factor (EGF) and oxidative stress, we measured the effect of this drug on these parameters in comparison to placebo.

METHODS

Thirty-nine patients with type-2 diabetes mellitus were randomized in a double blind, placebo-controlled clinical trial to receive either pentoxifylline 400 mg four times a day or placebo for 14 days. Blood samples were obtained at baseline and at the end of the study. Samples were analyzed for thiobarbituric reactive substances (TBARS) as a marker of lipid peroxidation, ferric reducing ability (total antioxidant power, TAP), EGF and NO levels.

RESULTS

Pentoxifylline in comparison to placebo was effective (P < 0.05) in reduction of lipid peroxidation in plasma of the patients without significant effects on TAP, levels of EGF and NO in plasma.

CONCLUSION

Adding of pentoxifylline to drug regimen of diabetic type-2 patients can be helpful. Exact mechanism of action of pentoxifylline in reduction of blood lipid peroxidation remains to be elucidated.

The Effect of Sildenafil on Pulmonary Embolism-Induced Oxidative Stress and Pulmonary Hypertension

Acute pulmonary embolism (APE) is a major cause of pulmonary hypertension and death. We examined the effects of sildenafil on the hemodynamic changes caused by APE in anesthetized dogs. Sham-operated dogs (n = 3) received only saline. APE was induced by stepwise IV injections of 300 mum microspheres in amounts adjusted to increase mean pulmonary artery pressures by 20 mm Hg. Hemodynamic evaluation was performed at baseline, after APE was induced, and then after sildenafil 0.25 mg/kg (n = 8), or sildenafil 1 mg/kg + 0.3 mg . kg(-1) . h(-1) (n = 8) or saline (n = 9) infusions were started. Similar experiments were conducted to examine the effects of sildenafil in rat isolated perfused lung preparation. Plasma thiobarbituric acid reactive species were also determined in both studies to measure oxidative stress. Both doses of sildenafil reduced mean pulmonary artery pressures in dogs by approximately 8 to 16 mm Hg (both P < 0.05) and attenuated the increase in oxidative stress after APE. Mean arterial blood pressure remained unaltered after both doses of sildenafil. Sildenafil produced similar effects after APE in rat isolated perfused lung preparation. These findings indicate that IV sildenafil can selectively attenuate the increases in mean pulmonary artery pressures after APE, possibly through antioxidant mechanisms.