The effects of inhalation of a novel nitric oxide donor, DETA/NO, in a patient with severe hypoxaemia due to acute respiratory distress syndrome

Development of Antimicrobial Nitric Oxide-Releasing Fibers

Nitric oxide (NO) is a highly reactive gas molecule, exhibiting antimicrobial properties. Because of its reactive nature, it is challenging to store and deliver NO efficiently as a therapeutic agent. The objective of this study was to develop NO-releasing polymeric fibers (NO-fibers), as an effective delivery platform for NO. NO-fibers were fabricated with biopolymer solutions of polyvinyl pyrrolidone (PVP) and ethylcellulose (EC), and derivatives of N-diazeniumdiolate (NONOate) as NO donor molecules, using an electrospinning system. We evaluated in vitro NO release kinetics, along with antimicrobial effects and cytotoxicity in microorganisms and human cell culture models. We also studied the long-term stability of NONOates in NO-fibers over 12 months. We demonstrated that the NO-fibers could release NO over 24 h, and showed inhibition of the growth of Pseudomonas aeruginosa (P. aeruginosa) and methicillin-resistant Staphylococcus aureus (MRSA), without causing cytotoxicity in human cells. NO-fibers were able to store NONOates for over 12 months at room temperature. This study presents the development of NO-fibers, and the feasibility of NO-fibers to efficiently store and deliver NO, which can be further developed as a bandage.

Polyamines - A New Metabolic Switch: Crosstalk With Networks Involving Senescence, Crop Improvement, and Mammalian Cancer Therapy

Polyamines (PAs) are low molecular weight organic cations comprising biogenic amines that play multiple roles in plant growth and senescence. PA metabolism was found to play a central role in metabolic and genetic reprogramming during dark-induced barley leaf senescence (DILS). Robust PA catabolism can impact the rate of senescence progression in plants. We opine that deciphering senescence-dependent polyamine-mediated multidirectional metabolic crosstalks is important to understand regulation and involvement of PAs in plant death and re-mobilization of nutrients during senescence. This will involve optimizing the use of PA biosynthesis inhibitors, robust transgenic approaches to modulate PA biosynthetic and catabolic genes, and developing novel germplasm enriched in pro- and anti-senescence traits to ensure sustained crop productivity. PA-mediated delay of senescence can extend the photosynthesis capacity, thereby increasing grain starch content in malting grains such as barley. On the other hand, accelerating the onset of senescence can lead to increases in mineral and nitrogen content in grains for animal feed. Unraveling the "polyamine metabolic switch" and delineating the roles of PAs in senescence should further our knowledge about autophagy mechanisms involved in plant senescence as well as mammalian systems. It is noteworthy that inhibitors of PA biosynthesis block cell viability in animal model systems (cell tumor lines) to control some cancers, in this instance, proliferative cancer cells were led toward cell death. Likewise, PA conjugates work as signal carriers for slow release of regulatory molecule nitric oxide in the targeted cells. Taken together, these and other outcomes provide examples for developing novel therapeutics for human health wellness as well as developing plant resistance/tolerance to stress stimuli.

Pharmacokinetics and pharmacodynamics of nitric oxide mimetic agents

Drug discovery focusing on NO mimetics has been hamstrung due to its unconventional nature. Central to these challenges is the fact that direct measurement of molecular NO in biological systems is exceedingly difficulty. Hence, drug development of NO mimetics must rely upon measurement of the NO donating specie (i.e., a prodrug) and a downstream marker of efficacy without directly measuring the molecule, NO, that is responsible for biological effect. The focus of this review is to catalog in vivo attempts to monitor the pharmacokinetics (PK) of the NO donating specie and the pharmacodynamic (PD) readout of NO bioactivity.

Fe-S Clusters Emerging as Targets of Therapeutic Drugs

Fe-S centers exhibit strong electronic plasticity, which is of importance for insuring fine redox tuning of protein biological properties. In accordance, Fe-S clusters are also highly sensitive to oxidation and can be very easily altered in vivo by different drugs, either directly or indirectly due to catabolic by-products, such as nitric oxide species (NOS) or reactive oxygen species (ROS). In case of metal ions, Fe-S cluster alteration might be the result of metal liganding to the coordinating sulfur atoms, as suggested for copper. Several drugs presented through this review are either capable of direct interaction with Fe-S clusters or of secondary Fe-S clusters alteration following ROS or NOS production. Reactions leading to Fe-S cluster disruption are also reported. Due to the recent interest and progress in Fe-S biology, it is very likely that an increasing number of drugs already used in clinics will emerge as molecules interfering with Fe-S centers in the near future. Targeting Fe-S centers could also become a promising strategy for drug development.

Nitric oxide generating/releasing materials

Harnessing the impressive therapeutic potential of nitric oxide (NO) remains an ongoing challenge. This paper describes several of the current strategies both with respect to the underlying chemistry and physics and to the applications where they have shown promise. Included in this overview are molecular systems such as NONOates that release NO through chemical reactions and delivery vehicles such as nanoparticles that can generate, store, transport and deliver NO and related bioactive forms of NO such as nitrosothiols. Although there has been much positive movement, it is clear that we are only at the early stages of knowing how to precisely produce, transport and deliver to targeted sites therapeutic levels of NO and related molecules.

Diazeniumdiolate reactivity in model membrane systems

The effect of small unilamellar phospholipid vesicles on the acid-catalyzed dissociation of nitric oxide from diazeniumdiolate ions, R(1)R(2)N[N(O)NO](-), [1: R(1)=H(2)N(CH(2))(3)-, R(2)=H(2)N(CH(2))(3)NH(CH(2))(4)-; 2: R(1)=R(2)=H(2)N(CH(2))(3)-; 3: R(1)=n-butyl-, R(2)=n-butyl-NH2+(CH(2))(6)-; 4: R(1)=R(2)=nPr-] has been examined at pH 7.4 and 37 degrees C. NO release was catalyzed by anionic liposomes (DPPG, DOPG, DMPS, POPS and DOPA) and by mixed phosphatidylglycerol/phosphatidylcholine (DPPG/DPPC and DOPG/DPPC) covesicles, while cationic liposomes derived from 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) and the zwitterionic liposome DMPC did not significantly affect the dissociation rates of the substrates examined. Enhancement of the dissociation rate constant in DPPG liposome media (0.010M phosphate buffer, pH 7.4, 37 degrees C) at 10mM phosphoglycerol levels, ranged from 37 for 1 to 1.2 for the anionic diazeniumdiolate 4, while DOPA effected the greatest rate enhancement, achieving 49-fold rate increases with 1 under similar conditions. The observed catalysis decreases with increase in the bulk concentration of electrolytes in the reaction media. Quantitative analysis of catalytic effects has been obtained through the application of pseudo-phase kinetic models and equilibrium binding constants at different liposome interfaces are compared. The stoichiometry of nitric oxide release from 1 and 2 in DPPG/DPPC liposome media has been obtained through oxyhemoglobin assay. DPPG=1,2-dipalmitoyl-sn-glycero-3-[phospho-rac-(1-glycerol)], DOPG=1,2-dioleoyl-sn-glycero-3-[phospho-rac-(1-glycerol)], DMPS=1,2-dimyristoyl-sn-glycero-3-[phospho-l-serine], POPS=1-palmitoyl-2-oleoyl-sn-glycero-3-[phospho-l-serine], DOPA=1,2-dioleoyl-sn-glycero-3-phosphate; DPPC=1,2-dipalmitoyl-sn-glycero-3-phosphocholine, DMPC=1,2-dimyristoyl-sn-glycero-3-phosphocholine, DOTAP=1,2-dioleoyl-3-trimethylammonium-propane.

Recent developments in nitric oxide donor drugs

During the 1980s, the free radical, nitric oxide (NO), was discovered to be a crucial signalling molecule, with wide-ranging functions in the cardiovascular, nervous and immune systems. Aside from providing a credible explanation for the actions of organic nitrates and sodium nitroprusside that have long been used in the treatment of angina and hypertensive crises respectively, the discovery generated great hopes for new NO-based treatments for a wide variety of ailments. Decades later, however, we are still awaiting novel licensed agents in this arena, despite an enormous research effort to this end. This review explores some of the most promising recent advances in NO donor drug development and addresses the challenges associated with NO as a therapeutic agent.

The nitric oxide/cGMP signaling pathway in pulmonary hypertension

This article briefly reviews the background of endothelium-dependent vasorelaxation, describes the nitric oxide/cGMP/protein kinase pathway and its role in modulating pulmonary vascular tone and remodeling, and describes three approaches that target the nitric oxide/cGMP pathway in the treatment of patients with pulmonary arterial hypertension.

The selective pulmonary vasodilatory effect of inhaled DETA/NO, a novel nitric oxide donor, in ARDS—a pilot human trial

OBJECTIVES

To examine the effects of inhaled NONOates in patients with acute respiratory distress syndrome (ARDS).

DESIGN

Case-series, phase I clinical trial.

SETTING

A multidisciplinary intensive care unit in a tertiary teaching hospital.

PATIENTS

Five consecutive patients with ARDS (men; age range, 47-76 years).

MEASUREMENTS

DETA/NO (150 micromol) was aerosolized into the lungs of patients on mechanical ventilation via the endotracheal tube over 20 minutes. Hemodynamic parameters were measured and blood samples were taken before, during, and after inhalation.

RESULTS

Compared to baseline values, pulmonary vascular resistance decreased until the end of the study period (180 minutes) while intrapulmonary shunting decreased significantly up to 45 min after DETA/NO aerosol administration. Inhaled DETA/NO had no effect on the systemic circulation (systemic blood pressure or cardiac output).

CONCLUSIONS

Inhaled DETA/NO is a selective pulmonary vasodilator in patients with ARDS. However, a larger number of patients is required to confirm the findings of this pilot study.

Intravenous and Intrapulmonary Administration of Honey Solution to Healthy Sheep: Effects on Blood Sugar, Renal and Liver Function Tests, Bone Marrow Function, Lipid Profile, and Carbon Tetrachloride-Induced Liver Injury

Safety of intravenous (i.v.) or intrapulmonary administration of different concentrations of honey and their effects on blood sugar, renal and liver function tests, bone marrow function, lipid profile, and carbon tetrachloride (CCl(4))-induced liver damage were studied. Healthy sheep of either sex, 6-8 months old, were assigned randomly into the following groups: sheep received i.v. infusion of 5% honey in normal saline at 10-day intervals for 50 days and were compared with sheep that received 5% dextrose; sheep received higher doses of honey (50 g of honey) by i.v. infusion daily for 10 days; sheep received four higher doses of honey (80 g each dose) for 2 weeks; sheep received subcutaneous injection of CCl(4) after four doses of i.v. infusion of 80 g of honey, and estimations of serum gamma-glutamyl transpeptidase (SGGT), serum glutamic oxaloacetic transaminase (SGOT), and serum glutamate pyruvate transaminase (SGPT) were performed daily for 10 days postinjection; sheep received i.v. infusion of 40 g of honey, and blood sugar estimation was performed for 3 h at 30-min intervals after infusion and compared with sheep that received 5% dextrose; sheep received rapid i.v. injection of 40% honey or 40% dextrose, and blood sugar was estimated before and after injection; sheep received various concentrations of honey in distilled water (0.5 mL/1.5 mL, 0.75 mL/1.75 mL and 1.2 mL/2.2 mL), and blood sugar estimation was performed before and after inhalation. Results showed that i.v. or intrapulmonary administration of honey did not cause any adverse effect. Intravenous delivery of honey by slow infusion caused improvement of renal and hepatic function, bone marrow function, and lipid profile. It reduced SGOT, SGPT, triglyceride, cholesterol, blood urea nitrogen, and blood sugar and elevated serum protein, serum albumin, hemoglobin, white blood cell, and neutrophil percentage. Similar results were obtained with the use of higher doses of honey. CCl(4) caused mild elevation of SGPT and SGGT and lowering of SGOT in sheep that received repeated i.v. administration of honey before administration of CCl(4), whereas in control sheep CCl(4) caused significant elevation of all the liver enzymes. Intravenous infusion of 40 g of honey caused elevation of blood sugar for 90 min postinfusion, whereas it decreased blood sugar at 2 and 3 h postinfusion as compared with fasting blood sugar. Dextrose caused significant elevation of blood sugar at all time intervals. Similar results were obtained with the use of 10% dextrose or 80 g of honey. Addition of honey to dextrose caused less hyperglycemia as compared with dextrose alone. Acute injection of 20 mL of 40% dextrose significantly elevated blood sugar for 3 h postinjection, whereas little elevation in blood sugar was obtained after injection of 40% honey; the difference between honey and dextrose was significant. Inhalation of honey caused significant lowering of blood sugar during and after inhalation as compared with fasting blood sugar and water inhalation. The effect was greater with a higher concentration of inhaled honey. It might be concluded that slow i.v. infusion or rapid i.v. injection of honey in different concentrations was safe and could lower blood sugar and improve renal, hepatic, and bone marrow functions and lipid profile. Intravenous honey had a hepatoprotective effect against CCl(4)-induced liver injury. Inhaled honey was safe and reduced blood sugar significantly.

Progress toward clinical application of the nitric oxide-releasing diazeniumdiolates

Diazeniumdiolates, compounds of structure R(1)R(2)NN(O)=NOR(3), which have also been called NONOates, have proven useful for treating an increasing diversity of medical disorders in relevant animal models. Here, I review the chemical features that make them such excellent starting points for designing materials capable of targeting reliable and controllable fluxes of bioactive NO for in vitro and in vivo applications. This is followed by a consideration of recent proof-of-concept studies that underscore what I believe to be the substantial clinical promise of such materials. Examples covered include progress toward inhibiting restenosis after angioplasty, preparing thromboresistant medical devices, reversing vasospasm, and relieving pulmonary hypertension. Together with a very recent report describing the beneficial effects of diazeniumdiolate therapy in a patient with acute respiratory distress syndrome, the results of the animal experiments support the prediction that a broad selection of problems in clinical medicine can be solved by judiciously mining the enormous variety of possible R(1)R(2)NN(O)=NOR(3) structures.

Diethylenetriamine nitric oxide adduct relaxes precontracted mouse tracheal smooth muscle

1. Inhaled diethylenetriamine nitric oxide adduct (DETA/NO) has been shown to be a selective pulmonary vasodilator in animal and human studies. The aims of the present study were to investigate the effect of DETA/NO on mouse precontracted isolated tracheal smooth muscle preparations and to determine the active component of this compound. 2. Mouse isolated tracheal smooth muscle rings were precontracted with carbachol (10-7 mol/L). Changes in isometric tension were recorded after cumulative addition of DETA (30-300 micromol/L; n = 6), DETA/NO (30-300 micromol/L; n = 9) or diluent control (n = 3). In addition, some preparations (n = 5) were pretreated with the soluble guanylyl cyclase (sGC) inhibitor 1H-[1,2,4]-oxadiazolo[4,3,-a]quinoxalin-1-one (ODQ; 30 micromol/L) before precontraction and exposure to DETA/NO. 3. Addition of DETA/NO caused a concentration-dependent relaxation of tracheal smooth muscle at 100 and 300 micromol/L, with an EC25%R of 109 micromol/L (95% confidence interval 72.6-164 micromol/L). The nucleophile amine carrier DETA had no effect on isometric tension. However, the relaxant effect of DETA/NO was completely abolished by pretreatment with ODQ. 4. We conclude that DETA/NO induces a concentration-dependent relaxation of mouse carbachol-contracted isolated tracheal smooth muscle that is mediated by NO released from DETA/NO via the activation of sGC.

Recent advances in the treatment of pulmonary hypertension

PURPOSE OF REVIEW

Pulmonary hypertension is a debilitating life-threatening disease of all ages. The long-term prognosis can be dismal despite maximal medical therapy. There have been significant advances in our understanding of the pathobiology and genetics of this disease, and novel pharmacological approaches appear to offer promising alternatives to conventional therapy. Anesthesiologists have been instrumental in the development and widespread clinical introduction of inhaled nitric oxide. Unfortunately, despite early optimism, inhaled nitric oxide has several significant limitations related to its cost, toxicity, required complex technology, and occasional therapeutic failure. Therefore, there is a need for an effective alternative pulmonary vasodilator. The early diagnosis and treatment of pulmonary hypertension are crucial if improvements are to be realized. This review will present recent work in this field in an attempt to increase anesthesiologists' awareness of potential new treatment options.

RECENT FINDINGS

Emerging data concerning the genetics of certain pulmonary hypertension variants have provided insight into the pathobiology of this disease and may lead to advances in the early detection or new treatment options. New pharmacological approaches include drugs such as nitric oxide donors, phosphodiesterase inhibitors, endothelin antagonists, and prostacyclin analogues. Attention has also been focused on the use of combinations of drugs of different classes.

SUMMARY

The clinical outcome of pulmonary hypertension is dependent upon early detection and therapy. Increased awareness of current therapeutic options will facilitate earlier effective treatment.

Two aerosolized nitric oxide adducts as selective pulmonary vasodilators for acute pulmonary hypertension

STUDY OBJECTIVES

To determine the selective vasodilatory effects of two inhaled "NONOate" aerosols in a closed chest pig model of acute pulmonary hypertension (APH).

METHODS

APH was induced by IV infusion of the prostaglandin H(2)/thromboxane A(2) receptor agonist (U46619). Aerosolized diethylenetriamine nitric oxide (NO) adduct (DETA/NO, n = 4), dipropylenetriamine NO adduct (DPTA/NO, n = 4) [60 micro mol each], or placebo (n = 4) was delivered via the trachea. Hemodynamic parameters and blood samples were measured before and after inhalation therapy.

RESULTS

Compared to control animals, pulmonary vascular resistance and pulmonary arterial pressure were significantly reduced from 10 to 105 min after DETA/NO administration and from 10 to 45 min after DPTA/NO aerosol administration (p < 0.05). Both aerosols had no significant effect on systemic vascular resistance or systemic BP. Serum nitrite significantly increased after the inhalation of both NONOates (p < 0.01). There was a tendency for reduced intrapulmonary shunting, particularly after treatment with DETA/NO.

CONCLUSION

Both DETA/NO and DPTA/NO administered as aerosols selectively reduced pulmonary hypertension induced by U46619.