Study of optical absorption cross-section spectra and high-order harmonic generation of thymine, thymine glycol, and thymine dimer molecules.

The last two decades have witnessed advances in femtosecond and sub-femtosecond physics which have made accessible the study of phenomena with atomic and subatomic resolution. In particular, developments in laser physics and high-order harmonic generation have enabled tracking and investigating molecular reaction dynamics and the actual dynamics of electrons in chemical reactions, as well as investigating the structure of molecules. High-order harmonic generation has proved to be an ideal means for generating autosecond pulses. Time-dependent density functional theory provides an invaluable tool for the theoretical study of high-order harmonic generation. In this article, an exact study of the optical absorption cross-section spectra and high-order harmonic generation of thymine and its damage forms (thymine glycol and thymine dimer) has been performed using the time dependent density functional theory via the octopus code. The spectra have been characterized with the aim of distinguishing thymine from its damaged forms. The discrepancies in the optical absorption spectra of thymine and its damaged forms have been elucidated. The effects of laser pulse intensity and pulse profile on the high-order harmonic spectra of these molecules has been investigated, showing the possibility to distinguish between thymine and its damaged forms using high-order harmonic generation. In particular, it is demonstrated that high-order harmonic generation corresponding to a laser pulse with a cosinusoidal envelope and intensity [Formula: see text] clearly differentiates thymine from its damaged forms. This laser could potentially be applied to discern damage in more complex DNA material.

Toxic potential of botulinum toxin type A on senescence in a Drosophila melanogaster model.

Botulinum toxin type-A (BoNT/A) application, especially neurological disorders, has been spread nowadays while it may cause side effects. The current study aimed to assess the BoNT/A dose-dependent effect on induction of aging in the Drosophila melanogaster model. The third instar larvae of Drosophila melanogaster were exposed to » LC50, ½ LC50, and LC50 of BoNT/A in the Drosophila diet for 48 h while H2O2 1% was used as a positive control. After the exposure time, some larvae were collected for molecular study, including gene expression analysis, comet assay, oxidative stress markers, and the phenotype changes. BoNT/A induced dose-dependent cytotoxicity, elevated reactive oxygen species (ROS) levels, and superoxide dismutase (SOD) enzyme activity. In addition, it caused DNA damage and activated caspase-3 and -9, and reduced the body size of the fly, especially in high doses. In line with the purpose of the study, aging markers, including ß-galactosidase (ß-gal), p16, p21, p38, and p53, were up-regulated by BoNT/A low dose. BoNT/A activates the aging pathway in the low dose, and increasing the dose induces toxicity, including oxidative stress, DNA damage, and apoptosis.

α-Lipoic acid prevents senescence, cell cycle arrest, and inflammatory cues in fibroblasts by inhibiting oxidative stress.

Senescence is a process characterized by an irreversible growth arrest in cells and induced by oxidative stress. In the current study, anti-aging potential of a well-known antioxidant, α-lipoic acid (α-LA), in rat embryonic fibroblast (REF) cells was assessed. In this regard, oxidative stress, inflammation, and apoptosis pathways were investigated on REF cells exposed to H2O2 as a senescence inducer and α-LA as a protective compound. In cells treated with α-LA and H2O2, level of ß-galactosidase, as an aging marker, and oxidative stress biomarkers, were significantly lower than those exposed to H2O2 only. Furthermore, flow cytometry assay showed that α-LA caused a significant reduction in the number of apoptotic cells via the caspase-dependent pathway. In addition, it could neutralize the inflammatory effects of H2O2 and attenuated the concentration of inflammatory cytokines. In comparison to H2O2 group, a significant increase in G0/G1 arrest was observed during cell cycle analysis in cells exposed to H2O2 and α-LA. The results of this study show that α-LA has beneficial effects on H2O2-induced cellular senescence. α-LA works by attenuating the reactive oxygen species, subsiding inflammation, and affecting cell division.

Molecular and biochemical evidence on the protective role of ellagic acid and silybin against oxidative stress-induced cellular aging.

Aging is a natural process in living organisms that is defined by some molecular and cellular changes with time. Various causes such as mitochondrial DNA aberrations, aggregation of proteins, telomere shortening, and oxidative stress have an influential role in aging of the cells. Natural antioxidants are compounds that are potent to protect the body from detrimental effects of molecules such as free radicals. The aim of this study was to evaluate the anti-aging properties of ellagic acid (EA) and silybin (SIL), as natural antioxidant compounds on rat embryonic fibroblast (REF) cells. These cells were pre-incubated with EA and SIL, thereafter were exposed to hydrogen peroxide (H2O2). Then, the cell viability, SA-ß-GAL activity, distribution of cell cycle, NF-κB, and mitochondrial complex I, II/IV enzyme activity were measured. The results of this study revealed the protective effects of EA and SIL in H2O2-treated REF cells, which confirm the previous achieved data on antioxidant and anti-inflammatory characteristics of EA and SIL against H2O2 in the treated REF cells. However, more new in vivo experiments are required to discover the anti-aging effects and mechanism of action of such compounds.

Preclinical assessment of ß-d-mannuronic acid (M2000) as a non-steroidal anti-inflammatory drug.

CONTEXT: ß-d-Mannuronic acid (M2000) has shown its therapeutic effects with the greatest tolerability and efficacy in various experimental models such as experimental autoimmune encephalomyelitis (EAE), adjuvant induced arthritis (AIA), nephrotic syndrome, and acute glomerulonephritis. Despite pharmacological effects of ß-D-mannuronic acid, there have been no systematic toxicological studies on its safety so far. OBJECTIVE: The study was designed to determine the acute and subchronic toxicity of ß-D-mannuronic acid, an anti-inflammatory agent, in healthy male NMRI mice and Wistar rats, respectively. MATERIALS AND METHODS: For the acute toxicity study, the animals received orally five different single doses of ß-D-mannuronic acid and were kept under observation for 14 d. In the subchronic study, 24 Wistar male rats were divided into four groups and were treated orally (gavage) once daily with test substance preparation at dose levels of 0, 50, 250, and 1250 mg/kg body weight for at least 63 consecutive days (9 weeks). Mortality, clinical signs, body weight changes, hematological and biochemical parameters, gross findings, organ weights, and histopathological determinations were monitored during the study. RESULTS: The results of acute toxicity indicated that the LD50 of ß-D-mannuronic acid is 4.6 g/kg. We found no mortality and no abnormality in clinical signs, body weight, relative organ weights, or necropsy in any of the animals in the subchronic study. Additionally, the results showed no significant difference in hematological, biochemical, and histopathological parameters in rats. CONCLUSIONS: Our results suggest that ß-D-mannuronic acid is relatively safe when administered orally in animals.

In situ stabilization of As and Sb with naturally occurring Mn, Al and Fe oxides in a calcareous soil: bioaccessibility, bioavailability and speciation studies.

This study investigated the effectiveness of 6 different types of naturally occurring manganese, aluminum and iron oxides for stabilization of As and Sb in a calcareous soil spiked with 50mgkg(-1) of As or Sb and two dosages of treatments (2% and 5%). The resulting contaminated soils were subjected to a series of chemical extraction studies including sequential extraction, single step extraction with DTPA and Simplified Bioaccessibility Extraction Test (SBET) for estimation of bioaccessible fraction of As and Sb in soil and a greenhouse experiment using barley as the test crop. The results showed that Fe-associated and carbonate-bound fraction of As and Sb were predominant fractions. However, the amounts of labile fractions were higher in As contaminated soils, whereas the percentage of Sb associated with crystalline Fe-oxide and residual fractions were higher. The results revealed that application of natural metal oxides reduced DTPA and SBET extractable amounts and plant uptake of As and Sb. After application of amendments, the exchangeable fraction of As decreased dramatically by up to 82% while Sb exchangeable fraction decreased by up to 60% depending upon the additive. The results of chemical extractions and plant uptake confirmed that Sb had lower bioavailability, compared with As.

Imidazolylchromanone oxime ethers as potential anticonvulsant agents: Anticonvulsive evaluation in PTZ-kindling model of epilepsy and SAR study.

As a continuation of our efforts to develop the azolylchromanone derivatives as potential anticonvulsant agents, we explored (Z)- and (E)-oxime ether derivatives of imidazolylchromanones bearing different lipophilic O-benzyl groups and tested their anticonvulsant activities in PTZ-kindling model of epilepsy. O-(2,4-Dichlorobenzyl) oximes 8a, 16a and 20a were significantly effective in delaying the onset of the PTZ-evoked seizures at the dose of 30mg/kg in kindled animals. The most effective compounds in delaying seizures were 7-chlorochromanone-O-(2,4-dichlorobenzyl) oximes 8a and 20a. SAR studies showed that introduction of a chlorine atom to the 7-position and/or a methyl group to the 2-position of the chroman ring resulted in an improvement of anti-seizure efficacy in O-(2,4-dichlorobenzyl) oxime series.

Implicit restart Lanczos as an eigensolver.

This paper investigates the efficiency of the implicit restart Lanczos and simple (without reorthogonalization) Lanczos algorithms, as eigensolvers for large scale computations in molecular and chemical physics. Using the cardioid billiard and the hydrogen cyanide/hydrogen isocyanide (HCN/HNC) molecule as model systems we demonstrate superior efficiency of implicit restart Lanczos compared to the simple Lanczos algorithm. A modified implementation of implicit restart Lanczos is also presented which works with a smaller Krylov space-with associated savings in memory-and can handle larger basis sets than the usual implicit restart Lanczos. It also enables getting all eigenpairs of a matrix, or all eigenvalues below a threshold (where the number of such is not known before hand), which is more difficult with the usual implicit restart algorithm.

Non-normal Lanczos methods for quantum scattering.

This article presents a new complex absorbing potential (CAP) block Lanczos method for computing scattering eigenfunctions and reaction probabilities. The method reduces the problem of computing energy eigenfunctions to solving two energy dependent systems of equations. An energy independent block Lanczos factorization casts the system into a block tridiagonal form, which can be solved very efficiently for all energies. We show that CAP-Lanczos methods exhibit instability due to the non-normality of CAP Hamiltonians and may break down for some systems. The instability is not due to loss of orthogonality but to non-normality of the Hamiltonian matrix. While use of a Woods-Saxon exponential CAP-as opposed to a polynomial CAP-reduced non-normality, it did not always ensure convergence. Our results indicate that the Arnoldi algorithm is more robust for non-normal systems and less prone to break down. An Arnoldi version of our method is applied to a nonadiabatic tunneling Hamiltonian with excellent results, while the Lanczos algorithm breaks down for this system.

Anticonvulsant and antiepileptogenic effects of azolylchromanones on lithium-pilocarpine induced seizures and pentylenetetrazole-kindling model of epilepsy.

Recently, we described the design and synthesis of azolylchroman derivatives as conformationally constrained analogs of (arylalkyl)azole anticonvulsants. In the present study, two distinct pharmacological models, lithium-pilocarpine induced seizure and PTZ-induced kindling were used to investigate both anticonvulsive and antiepileptogenic properties of the selected azolylchromanones including 7-chloro-3-(1H-imidazol-1-yl)chroman-4-one (I), 3-(1H-1,2,4-triazol-1-yl)chroman-4-one (II), trans-3-(1H-imidazol-1-yl)-2-methylchroman-4-one (III) and trans-7-chloro-3-(1H-imidazol-1-yl)-2-methylchroman-4-one (IV). Although compounds I and II were highly effective at the dose of 5 mg/kg against acute PTZ-induced convulsions as previously reported by us, these compounds exhibited limited effects in PTZ-induced kindling model. However, compound I was found to exert respectable action in delaying seizures and reducing seizure index at the dose of 10 mg/kg. In contrast, all tested compounds showed an anticonvulsant effect due to the considerably delayed onset of seizures in lithium-pilocarpine model. Compound I exhibited more effective action in delaying seizures as well as decreasing seizure duration in this model of epilepsy. In conclusion, the azolylchromanones I-IV, especially 7-chloro-3-(1H-imidazol-1-yl)chroman-4-one (I), were effective against lithium-pilocarpine induced status epilepticus, suggesting the potential application of the test compounds in the treatment of status epilepticus.

Rat Plasma Oxidation Status After Nigella Sativa L. Botanical Treatment in CCL(4)-Treated Rats.

ABSTRACT Nigella sativa Linn. (family Ranunculaceae), commonly known as black cumin, is native to the Mediterranean area and has been used for thousands of years as a health and beauty aid. The present study investigated the protective effects of Nigella sativa (NS) extract (NSE) and oil (NSO) on CCl(4)-induced nitrosative stress and protein oxidation in rat. CCl(4) (0.8 mg/kg) was used as an aid for induction of nitrosative stress. In vitro antioxidant potential was tested in the presence of 2,4-dinitrophenylhyrdazine (DPPH) as an organic nitrogen radical. Doses of 0.2, 0.3, and 1 mg/kg of the NS extract and oil were administered to CCL(4)-treated rats for 10 days. At the end of treatment, blood was taken from rats under anesthesia and plasma was separated. The concentration of nitric oxide (NO), total antioxidant power (TAP), carbonyl molecules (CM) as measure of protein oxidation (PO), tumor necrosis factor-alpha (TNF-alpha), and total thiol molecules (TTM) were measured in plasma. In vitro evaluation of antioxidant effects of NSE and NSO showed that the highest antioxidant activity (80%) was observed with the concentration of 10 and 20 mg/ml, respectively, that were equal to vitamin E (200 mg/ml). Administration of CCL(4) increased plasma PO, NO, TNF-alpha and decreased TAP and TTM. Both NSE and NSO showed significant protection against CCl(4)-induced changes in biochemical parameters, but not dose-dependently. Doses of 0.3 and 1 mg/kg were more effective than doses of 0.2 mg/kg for both NSE and NSO, but dose of 1 mg/kg was the most effective one. The results indicate the potential of NS in preventing CCL(4)-induced toxic nitrosative stress. It is concluded that NS has marked antioxidant potentials that may be beneficial in alleviating complications of many illnesses related to oxidative/nitrosative stress in humans, but preclinical safety measures should be completed before clinical trials.

Long time wave packet dynamics from energy eigenfunctions: nonuniform energy resolution via adaptive bisection fast Fourier transformation.

This article presents a new approach to long time wave packet propagation. The methodology relies on energy domain calculations and an on-the-surface straightforward energy to time transformation to provide wave packet time evolution. The adaptive bisection fast Fourier transform method employs selective bisection to create a multiresolution energy grid, dense near resonances. To implement fast Fourier transforms on the nonuniform grid, the uniform grid corresponding to the finest resolution is reconstructed using an iterative interpolation process. By proper choice of the energy grid points, we are able to produce results equivalent to grids of the finest resolution, with far fewer grid points. We have seen savings 20-fold in the number of eigenfunction calculations. Since the method requires computation of energy eigenfunctions, it is best suited for situations where many wave packet propagations are of interest at a fixed small set of points--as in time dependent flux computations. The fast Fourier transform (FFT) algorithm used is an adaptation of the Danielson-Lanczos FFT algorithm to sparse input data. A specific advantage of the adaptive bisection FFT is the possibility of long time wave packet propagations showing slow resonant decay. A method is discussed for obtaining resonance parameters by least squares fitting of energy domain data. The key innovation presented is the means of separating out the smooth background from the sharp resonance structure.

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.

Protective Effects of alpha-Tocopherol and N-Acetyl-Cysteine on Diazinon-Induced Oxidative Stress and Acetylcholinesterase Inhibition in Rats.

ABSTRACT Diazinon, an organophosphate (OP) insecticide, is widely used in agriculture and domestically. Reactive oxygen species (ROS) caused by OPs are involved in the toxicity of various pesticides. The aim of the present study was to analyze the role of diazinon in inducing oxidative stress in adult male Wistar rats and to evaluate the possible protective effects of alpha-tocopherol (TPH) and the glutathione prodrug N-acetyl-cysteine (NAC) after 4 weeks of exposure to a sublethal dose of diazinon. TPH (10 mg/kg/day), NAC (160 mg/kg/day), diazinon (25 mg/kg/day), a combination of NAC (160 mg/kg/day) and diazinon (25 mg/kg/day), and a combination of TPH (10 mg/kg/day) and diazinon (25 mg/kg/day) were given to rats orally via gavage for 4 weeks. The thiobarbituric acid reactive substances (TBARS) marker of lipid peroxides levels, total thiol molecules, and total antioxidant capacity of plasma were all analyzed as biomarkers of oxidative stress. In addition, the acetylcholinesterase (AChE) activity was measured as a biomarker of toxicity. The results from this study well indicate diazinon-induced oxidative stress demonstrated by enhanced TBARS, decreased total thiol molecules, and total antioxidant capacity. In addition, AChE activity was inhibited as a marker of OP toxicity. Data show the protective roles of TPH and NAC in reducing the diazinon-induced oxidative stress. Interestingly, both TPH and NAC recovered diazinon-induced AChE inhibition. It is concluded that supplementation with TPH and NAC can reduce toxicity of OP in human exposure.

Effect of Satureja khuzestanica essential oil on male rat fertility.

This study was undertaken to study the effect of Satureja khuzestanica essential oil (SKEO) in male rat fertility. SKEO was administered orally at doses of 75, 150, and 225 mg/kg/day for 45 days through drinking water. Treated and control rats were mated with female on day 45 of treatment. SKEO significantly improved all the parameters evaluated such as potency, fecundity, fertility index, and litter size. Moreover, concentrations of FSH and testosterone were significantly increased in SKEO-treated groups. Also the weights of testes, seminal vesicles, and ventral prostate weights were increased by SKEO (225 mg/kg). Histopathological analysis showed that in male rats treated with SKEO (150, 225 mg/kg) the number of spermatogonium, spermatid cords, Leydig cells, and spermatozoids was increased. Also in these groups, the Sertoli cells were hypertrophic.

Antioxidant potentials of Iranian Carica papaya juice in vitro and in vivo are comparable to alpha-tocopherol.

Carica papaya is widely cultivated throughout the world and is used as a food and also as a traditional medicine, particularly as an antiseptic and contraceptive. The present study was designed to explore the toxicological and antioxidant potential of dried C. papaya juice in vitro and in vivo. The oral LD(50) of the juice of C. papaya was determined, and the antioxidant potentials determined by DPPH and FRAP tests. In vivo examination was performed after oral administration of dried papaya juice to rats for 2 weeks at doses of 100, 200 and 400 mg/kg. Blood TBARS and FRAP assays were used to determine the potential of the juice to act against oxidative stress. The acute toxicity test (LD(50)) demonstrated that papaya juice is not lethal up to a dose of 1500 mg/kg after oral administration and thus is considered nontoxic. In treated groups, no sign of toxicity was observed. In vitro evaluation of the antioxidant effects of papaya showed that the highest antioxidant activity (80%) was observed with a concentration of 17.6 mg/mL. Blood lipid peroxidation levels decreased significantly after administration of all doses of papaya juice (100, 200, 400 mg/kg/day) to 35.5%, 39.5% and 40.86% of the control, respectively, compared with a value of 28.8% for vitamin E. The blood total antioxidant power was increased significantly by all doses of papaya juice (100, 200, 400 mg/kg/day) to 11.11%, 23.58% and 23.14% of the control, respectively. The value for vitamin E was 18.44%. This preliminary study indicates the safety and antioxidative stress potential of the juice of C. papaya, which was found to be comparable to the standard antioxidant compound alpha-tocopherol.

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.

Alteration of cyclic nucleotides levels and oxidative stress in saliva of human subjects with periodontitis.

Experimental findings suggest a protective role for cyclic nucleotides against induction of oxidative stress in saliva. Oxidative stress is a major contributor to the pathogenesis of inflammatory diseases. This study was conducted to evaluate salivary oxidative stress along with cGMP and cAMP levels in periodontitis subjects. cAMP and cGMP are second messengers that have important roles in salivary gland functions. Unstimulated whole saliva samples were obtained from periodontitis patients and age- and sex-matched healthy individuals. Saliva samples were analyzed for thiobarbituric reactive substances (TBARS) as a marker of lipid peroxidation, ferric reducing ability (total antioxidant power, TAP), and levels of cAMP and cGMP. Concentrations of cAMP and cGMP were reduced in the saliva of patients with moderate and severe periodontitis. Saliva of patients with severe periodontitis had higher TBARS and lower TAP than control subjects. The presence of oxidative stress and lower levels of salivary cGMP and cAMP in periodontitis are in association with disease severity.

Reduction of diabetes-induced oxidative stress by phosphodiesterase inhibitors in rats.

Increased oxidative stress has been suggested to be involved in the pathogenesis and progression of diabetic tissue damage. The aim of this study was to investigate the effect of different phosphodiesterase inhibitors on lipid peroxidation and total antioxidant capacity (TAC) of plasma in streptozotocin-induced diabetic rats (Rattus norvegicus). Rats became diabetic by a single administration of streptozotocin (STZ, 45 mg/kg). The effects of 15-days treatment by milrinone, sildenafil, and theophylline as cyclic-AMP and -GMP phosphodiesterase inhibitors (PDEIs) on diabetes-induced oxidative stress were studied. The levels of glucose, malonedialdehyde (MDA) the by product of lipid peroxides, and TAC (FRAP test) were estimated in plasma of control and experimental groups of rats. A significant increase in the levels of plasma glucose, and MDA and a concomitant decrease in the levels of TAC were observed in diabetic rats. These alterations were reverted back to near normal level after the treatment with PDEIs. Treatment of diabetic rats by PDEIs reduced MDA levels and increased TAC in the order of milrinone>sildenafil>theophylline. In conclusion, the present investigation show that PDIS possesses antioxidant activities, which may be attributed to their enhancing effect on cellular cyclic nucleotides contributing to the protection against oxidative stress in streptozotocin-induced diabetes. Exact mechanism of protective actions of cAMP- and cGMP-phosphodiesterase remains to be elucidated by further studies. This finding may suggest a place for PDEIs in maintaining health in diabetes.