purines

Levels of DNA damage in groups of 10 patients with insulin-dependent diabetes mellitus and 10 matched controls were compared using the comet assay; DNA strand breaks, oxidized pyrimidines (endonuclease III-sensitive sites) and altered purines (sites sensitive to formamidopyrimidine glycosylase) were measured. Mean values of strand breaks and oxidized pyrimidines were significantly higher in diabetics. Strand breaks correlated with body mass index in the diabetic group. A strong correlation was seen between formamidopyrimidine glycosylase-sensitive sites and serum glucose concentrations. When three patients with normal glucose levels were excluded from the statistical analysis, the mean value of formamidopyrimidine glycosylase-sensitive sites was very significantly elevated compared with normal. DNA damage in lymphocytes is thus a useful marker of oxidative stress, and in particular formamidopyrimidine glycosylase-sensitive sites seem to represent changes specifically related to hyperglycemia.

Purpose: The cyclin-dependent kinase (CDK) 4/6 inhibitor, ribociclib (LEE011), displayed preclinical activity in neuroblastoma and malignant rhabdoid tumor (MRT) models. In this phase I study, the maximum tolerated dose (MTD) and recommended phase II dose (RP2D), safety, pharmacokinetics (PK), and preliminary activity of single-agent ribociclib were investigated in pediatric patients with neuroblastoma, MRT, or other cyclin D-CDK4/6-INK4-retinoblastoma pathway-altered tumors.Experimental Design: Patients (aged 1-21 years) received escalating once-daily oral doses of ribociclib (3-weeks-on/1-week-off). Dose escalation was guided by a Bayesian logistic regression model with overdose control and real--time PK.Results: Thirty-two patients (median age, 5.5 years) received ribociclib 280, 350, or 470 mg/m(2) Three patients had dose-limiting toxicities of grade 3 fatigue (280 mg/m(2); n = 1) or grade 4 thrombocytopenia (470 mg/m(2); n = 2). Most common treatment-related adverse events (AE)...

Arcobacter butzleri is an emerging pathogen that has been implicated as the causative agent of persistent watery diarrhea. We describe a case involving a patient with chronic lymphocytic leukemia who developed invasive A. butzleri bacteremia. This case illustrates the unique challenges involved in diagnosing infections caused by emerging gastrointestinal pathogens.

Aging in men is accompanied by a decrease in libido and sexual activity. Recently, it has been demonstrated that a significant proportion of men >60 yr of age has biochemical hypogonadism. Hypoandrogenism, which is associated with other conditions that negatively influence erectile activity, may be an important cofactor in the induction of erectile dysfunction and in the response to phosphodiesterase type 5 (PDE5) inhibitors in aging. In these patients, administration of 50 mg sildenafil or 3 mg apomorphine has no influence on erectile function. Recently we showed that, in hypogonadal subjects, testosterone treatment might stimulate endothelial and neuronal production of vasoactive substances like nitric oxide (NO). Furthermore it can improve endothelial repair mechanisms by increasing bone marrow-derived endothelial progenitor cell (EPC) number in the peripheral circulation. Finally, the normal response to pharmacological stimulation with apomorphine or sildenafil, observed in h...

We report a case of a 37-years-old man, affected by thalassemia major, hypogonadotropic hypogonadism, chronic HCV-hepatitis, diabetes mellitus, severe osteoporosis, prior septic pulmonary embolism and pulmonary artery hypertension was performed a long-term treatment with high-dose of sildenafil (120 mg/die) with reduction of pulmonary arterial systolic pressure and of the dyspnea.

Sildenafil, a selective inhibitor of phosphodiesterase type 5, produces relaxation of isolated epicardial coronary artery segments by causing accumulation of cGMP. Because shear-induced nitric oxide-dependent vasodilation is mediated by cGMP, this study was performed to determine whether sildenafil would augment the coronary resistance vessel dilation that occurs during the high-flow states of exercise or reactive hyperemia. In chronically instrumented dogs, sildenafil (2 mg/kg per os) augmented the vasodilator response to acetylcholine, with a leftward shift of the dose-response curve relating coronary flow to acetylcholine dose. Sildenafil caused a 6. 7 +/- 2.1 mmHg decrease of mean aortic pressure, which was similar at rest and during treadmill exercise (P < 0.05), with no change of heart rate, left ventricular (LV) systolic pressure, or LV maximal first time derivative of LV pressure. Sildenafil tended to increase myocardial blood flow at rest and during exercise (mean increa...

Sildenafil is a phosphodiesterase-5 (PDE5) inhibitor and is predominantly used in the treatment of erectile dysfunction. While maintaining an excellent safety and tolerability profile in the management of erectile dysfunction, sildenafil also provides a prolonged benefit in various other diseases. Sildenafil has been shown to have a potential therapeutic efficacy for disorders related to the central nervous system and pulmonary system. In the central nervous system, it exerts its neuroprotective effects in multiple sclerosis and has a significant memory enhancing action. Sildenafil also significantly enhances neurogenesis. Several lines of evidence indicate that targeting PDE5 with sildenafil offers novel strategies in the treatment of age-related memory impairment. Guanylate cyclase/cGMP/protein kinase G pathway or glutamate/nitric oxide/cGMP pathway appears to mediate memory enhancing effects. Some of the positive cognitive features of sildenafil therapy are likely attributable to...

This study assessed the non-inferiority and safety of regadenoson administration during recovery from inadequate exercise compared with administration without exercise. Patients unable to achieve adequate exercise stress were randomized to regadenoson 0.4 mg either during recovery (Ex-Reg) or 1 hour after inadequate exercise (Regadenoson) (MPI1). All patients also underwent non-exercise regadenoson MPI 1-14 days later (MPI2). The number of segments with reversible perfusion defects (RPDs) detected using single photon emission computerized tomography imaging was categorized. The primary analysis evaluated the majority agreement rate between Ex-Reg and Regadenoson groups. 1,147 patients were randomized. The lower bound of the 95% confidence interval of the difference in agreement rates (-6%) was above the -7.5% non-inferiority margin, demonstrating non-inferiority of Ex-Reg to Regadenoson. Adverse events were numerically less with Ex-Reg (MPI1). In the Ex-Reg group, one patient develo...

Advances in cancer treatment have greatly improved survival rates of children with cancer. However, these same chemotherapeutic or radiologic treatments may result in long-term health consequences. Anthracyclines, chemotherapeutic drugs commonly used to treat children with cancer, are known to be cardiotoxic, but the mechanism by which they induce cardiac damage is still not fully understood. A higher cumulative anthracycline dose and a younger age of diagnosis are only a few of the many risk factors that identify the children at increased risk of developing cardiotoxicity. While cardiotoxicity can develop at anytime, starting from treatment initiation and well into adulthood, identifying the best cardioprotective measures to minimize the long-term damage caused by anthracyclines in children is imperative. Dexrazoxane is the only known agent to date, that is associated with less cardiac dysfunction, without reducing the oncologic efficacy of the anthracycline doxorubicin in children...

We demonstrate a novel dual strategy against inflammation and pain through body-wide desensitization of nociceptors via TRPA1. Attenuation of experimental colitis by capsazepine (CPZ) has long been attributed to its antagonistic action on TRPV1 and associated inhibition of neurogenic inflammation. In contrast, we found that CPZ exerts its anti-inflammatory effects via profound desensitization of TRPA1. Micromolar CPZ induced calcium influx in isolated dorsal root ganglion (DRG) neurons from wild-type (WT) but not TRPA1-deficient mice. CPZ-induced calcium transients in human TRPA1-expressing HEK293t cells were blocked by the selective TRPA1 antagonists HC 030031 and A967079 and involved three cysteine residues in the N-terminal domain. Intriguingly, both colonic enemas and drinking water with CPZ led to profound systemic hypoalgesia in WT and TRPV1(-/-) but not TRPA1(-/-) mice. These findings may guide the development of a novel class of disease-modifying drugs with anti-inflammatory...

Normal nurse shark and lemon shark sera contain ∼17S and 7S immunoglobulins with anti-dinitrophenyl activity. Specifically purified 17S “anti-DNP” precipitated in gels with DNP-BSA conjugates, bound to DNP-immunoadsorbents (∼60%) but did not give detectable binding by equilibrium dialysis. The 7S “anti-DNP” did not precipitate in gels, nor did it bind radiolabeled hapten and only about 25% bound to DNP-immunoadsorbents. Of special interest was the observation that specifically purified 17S “anti-DNP” also agglutinated sheep erythrocytes. However, the agglutination of sheep erythrocytes could not be inhibited with DNP-OH. Whole nurse shark serum contains agglutinins to both sheep and chicken erythrocytes. Experiments showed that this was not due to heteroligating antibodies. The possibility is raised that many of the shark immunoglobulin molecules have a dual function, that is, as antibody and as a carrier for certain hormones or other small molecules.

Sildenafil citrate (Viagra) is the most widely used pharmacological drug for treating erectile dysfunction in men. It has potent cardioprotective effects against ischemia-reperfusion injury via nitric oxide and opening of mitochondrial ATP-sensitive K+ channels. We further investigated the role of protein kinase C (PKC)-dependent signaling pathway in sildenafil-induced cardioprotection. Rabbits were treated (orally) with sildenafil citrate (1.4 mg/kg) 30 min before index ischemia for 30 min and reperfusion for 3 h. The PKC inhibitor chelerythrine (5 mg/kg iv) was given 5 min before sildenafil. Infarct size (% of risk area) reduced from 33.65 ± 2.17 in the vehicle (saline) group to 15.07 ± 0.63 in sildenafil-treated groups, a 45% reduction compared with vehicle (mean ± SE, P < 0.05). Chelerythrine abolished sildenafil-induced protection, as demonstrated by increase in infarct size to 31.14 ± 2.4 ( P < 0.05). Chelerythrine alone had an infarct size of 33.5 ± 2.5, which was not s...

Neutrophils are the most abundant leukocyte and play a central role in the immune defense against rapidly dividing bacteria. However, they are also the shortest lived cell in the blood with a lifespan in the circulation of 5.4 days. The mechanisms underlying their short lifespan and spontaneous entry into apoptosis are poorly understood. Recently, the broad range cyclin-dependent kinase (CDK) inhibitor R-roscovitine was shown to increase neutrophil apoptosis, implicating CDKs in the regulation of neutrophil lifespan. To determine which CDKs were involved in regulating neutrophil lifespan we first examined CDK expression in human neutrophils and found that only three CDKs: CDK5, CDK7 and CDK9 were expressed in these cells. The use of CDK inhibitors with differing selectivity towards the various CDKs suggested that CDK9 activity regulates neutrophil lifespan. Furthermore CDK9 activity and the expression of its activating partner cyclin T1 both declined as neutrophils aged and entered ...

We have produced a polyclonal antibody that specifically recognizes cGMP-binding cGMP-specific phosphodiesterase (PDE5). The antibody was raised in rabbit using as immunogen a fusion protein, in which glutathione S-transferase was coupled to a 171 amino acid polypeptide ...

Two isomeric series of new thieno-fused 7-deazapurine ribonucleosides (derived from 4-substituted thieno[2',3':4,5]pyrrolo[2,3-d]pyrimidines and thieno[3',2':4,5]pyrrolo[2,3-d]pyrimidines) were synthesized by a sequence involving Negishi coupling of 4,6-dichloropyrimidine with iodothiophenes, nucleophilic azidation, and cyclization of tetrazolopyrimidines, followed by glycosylation and cross-couplings or nucleophilic substitutions at position 4. Most nucleosides (from both isomeric series) exerted low micromolar or submicromolar in vitro cytostatic activities against a broad panel of cancer and leukemia cell lines and some antiviral activity against HCV. The most active were the 6-methoxy, 6-methylsulfanyl, and 6-methyl derivatives, which were highly active to cancer cells and less toxic or nontoxic to fibroblasts.

Tetrahydrolipstatin (orlistat), an inhibitor of lipases and fatty acid synthase, is used orally for long-term treatment of obesity. Although the drug possesses striking antitumor activities in vitro against human cancer cells and in vitro and in vivo against animal tumors, it also induces precancerous lesions in rat colon. Therefore, we tested the in vitro effect of orlistat on the expression of O6-methylguanine-DNA methyltransferase (MGMT), a DNA repair enzyme that plays an essential role in the control of mutagenesis and carcinogenesis. Western blot analysis demonstrated that 2-day continuous exposure to 40 µM orlistat did not affect MGMT levels in a human melanoma cell line, but downregulated the repair protein by 30-70% in human peripheral blood mononuclear cells, in two leukemia and two colon cancer cell lines. On the other hand, orlistat did not alter noticeably MGMT mRNA expression. Differently from lomeguatrib (a false substrate, strong inhibitor of MGMT) orlistat did not re...

To determine the occurrence of clinically significant decreases in blood pressure (BP) with sildenafil use in normotensive and hypertensive men by means of ambulatory BP monitoring. On 2 nights, 49 men (22 hypertensive, 27 normotensive) had their ambulatory systolic BP (SBP), diastolic BP (DBP), and heart rate monitored during the first 3 hours (waking period) and every 30 minutes after midnight for 3 additional hours (sleeping period). No medication was taken on one night; sildenafil 100 mg was taken on the other. Sildenafil decreased SBP (-6.0 mm Hg; P = 0.0003), DBP (-4.5 mm Hg; P = 0.001), and mean arterial pressure (-5.3 mm Hg; P = 0.00008). The BP-lowering effects of sildenafil did not differ significantly in the normotensive and hypertensive men. Age significantly affected the BP reductions; decreases in SBP, DBP, and mean arterial pressure were greater in men 49 years old and older than in those younger than 49 years old. According to readings averaged over the entire contro...

Purinergic inhibition of Na-K-Cl cotransport has been noted in various renal epithelial cells derived from the collecting tubule, including Madin-Darby canine kidney (MDCK) cells. In recent studies, we have observed purinergic inhibition of Na-K-Cl cotransport in C11-MDCK subclones (α-intercalated-like cells). Interestingly, Na-K-Cl cotransport activity was also detected in C7-MDCK subclones (principal-like cells) but was not affected by ATP. In this investigation, we have transfected the human Na-K-Cl cotransporter (huNKCC1) in both C11 and C7 cells to determine whether these differences in NKCC regulation by ATP were due to cell-specific purinoceptor signaling pathways or to cell-specific isoforms/splice variants of the transporter. In both cell lines, we found that endogenous as well as huNKCC1-derived cotransport activity was restricted to the basolateral side. In addition, we were able to show that extracellular application of 100 μM ATP or 100 μM UTP abolished NKCC activity in...

Eight dual-flow continuous-culture fermenters were used in four replicated periods to compare the effects of diet and microbial marker on estimates of N metabolism in continuous culture of ruminal microorganisms. A basal diet was supplemented with urea and tryptone, soybean meal (SBM), lignosulfonate-treated SBM, corn gluten meal, blood meal (BM), hydrolyzed feather meal, fish meal (FM), or meat and bone meal (MBM). Microbial protein flow and protein degradation in fermenters were estimated using purines, purine N, and 15N in bacteria obtained from fermenter flasks or from the effluent. The ratio of purine N to total N in bacteria averaged .083 and was not affected (P > .05) by treatment. Dietary purine content (percentage of DM) ranged from .033 in BM to .084 in FM. Escape of feed purine N (percentage of total purine N flow) averaged 1.7% (SE = 2.9) and was not different (P > .05) among treatments. Bacterial N flows obtained using purines were more variable than estimates obt...

Over a decade ago, sildenafil, the first phosphodiesterase type 5 (PDE5) inhibitor, became available and revolutionized the treatment of erectile dysfunction (ED). Ever since, several other agents, such as vardenafil and tadalafil, have enriched the spectrum of therapy offering therapeutic flexibility. The fascinating background of PDE5 inhibitors is that they were initially developed for cardiovascular treatment, and this aspect has