Investigating the potential of statin medications as a nitric oxide (NO) release agent to decrease decompression sickness: A review article

Evolution of the plasma proteome of divers before and after a single SCUBA dive

PURPOSE

Decompression sickness (DCS) is a poorly understood and complex systemic disease caused by inadequate desaturation following a reduction of ambient pressure. A previous proteomic study of ours showed that DCS occurrence but not diving was associated with changes in the plasma proteome in rats, including a dramatic decrease of abundance of the tetrameric form of Transthyretin (TTR). The present study aims to assess the impact on the human blood proteome of a dive inducing significant decompression stress but without inducing DCS symptoms.

EXPERIMENTAL DESIGN

Twelve healthy male divers were subjected to a single dive at a depth of 18 m of sea water (msw) with a 47-min bottom time followed by a direct ascent to the surface at a rate of 9 msw/min. Venous blood was collected before the dive as well as 30 min and 2 h following the dive. The plasma proteomes from four individuals were then analyzed by using a two-dimensional electrophoresis-based proteomic strategy.

RESULTS

No protein spot showed a significantly changed abundance (fdr< 0.1) between the tested times.

CONCLUSION

These results strengthen the hypothesis according to which significant changes of the plasma proteome measurable with two-dimensional electrophoresis may only occur along with DCS symptoms.

Preventive effect of rosiglitazone on liver injury in a mouse model of decompression sickness

BACKGROUND AND AIMS

Severe decompression sickness (DCS) is a multi-organ injury. This study investigated the preventive effects of rosiglitazone on liver injury following rapid decompression in mice and examined the underlying mechanisms.

METHODS

Mice were randomly divided into four groups: a control group, vehicle group, and rosiglitazone (5 and 10 mg·kg⁻¹) groups, the latter three being exposed to a pressure of 911 kPa. Haematoxylin and eosin staining, plasma levels of alanine transaminase (ALT), aspartate transaminase (AST) and lactate dehydrogenase and blood cell counts were used to evaluate liver injury at 30 min after rapid decompression. The expression of endothelial and inducible nitric oxide synthase (iNOS) and its phosphorylation were measured to uncover the underlying molecular mechanisms.

RESULTS

A significant increase in plasma ALT, red blood cells and platelets, and a decrease in neutrophils were observed in the vehicle group. Furthermore, the expression of iNOS, E-selectin and the total level of NO in hepatic tissue, and soluble E-selectin in the plasma were significantly elevated in the vehicle group. Rosiglitazone pre-treatment prevented the increases in ALT (and AST), soluble E-selectin concentration, red blood cells and platelet counts. Moreover, rosiglitazone reduced over-expression of iNOS and the NO level, prevented the fall in neutrophil count and promoted the phosphorylation of iNOS in the liver.

CONCLUSIONS

Pre-treatment with rosiglitazone ameliorated liver injury from severe DCS. This preventive effect may be partly mediated by stimulating endothelial NO production, improving endothelial function and limiting inflammatory processes.

Surface tension in human pathophysiology and its application as a medical diagnostic tool

Introduction: Pathological features of disease appear to be quite different. Despite this diversity, the common feature of various disorders underlies physicochemical and biochemical factors such as surface tension. Human biological fluids comprise various proteins and phospholipids which are capable of adsorption at fluid interfaces and play a vital role in the physiological function of human organs. Surface tension of body fluids correlates directly to the development of pathological states.

Methods: In this review, the variety of human diseases mediated by the surface tension changes of biological phenomena and the failure of biological fluids to remain in their native state are discussed.

Results: Dynamic surface tension measurements of human biological fluids depend on various parameters such as sex, age and changes during pregnancy or certain disease. It is expected that studies of surface tension behavior of human biological fluids will provide additional information and might become useful in medical practice. Theoretical background on surface tension measurement and surface tension values of reference fluids obtained from healthy and sick patients are depicted.

Conclusion: It is well accepted that no single biomarker will be effective in clinical diagnosis. The surface tension measurement combined with routine lab tests may be a novel non-invasive method which can not only facilitate the discovery of diagnostic models for various diseases and its severity, but also be a useful tool for monitoring treatment efficacy. We therefore expect that studies of surface tension behavior of human biological fluids will provide additional useful information in medical practice.

Statins role in the prevention and treatment of sepsis

Sepsis is a complex disease with typically poor outcomes. While the onset of sepsis is typically infectious, the detrimental consequences follow pathogen toxin release that produces activation of numerous cytokines and a pro-inflammatory response. These same cytokines also stimulate activation of coagulation and inhibit natural fibrinolysis. Despite decades of research targeted against these pathways the development of sepsis and mortality in patients with sepsis remains high. While statins were developed for reducing cholesterol in patients with atherosclerotic disease, we now know they have a number of other properties which may be helpful in the prevention and treatment of sepsis. Statins have demonstrated the ability to reduce a number of pro-inflammatory cytokines known to be detrimental in the development and progression of sepsis. Statins have also demonstrated the ability to limit the coagulation response and promote fibrinolysis in the setting of sepsis. Based on these encouraging pharmacologic properties of statins a number of trials have been conducted evaluating the impact of statins on the prevention and treatment of sepsis. Most of the trials to date have been retrospective cohort trials, with very few prospective randomized trials. While some trials fail to demonstrate a benefit of statins, most trials suggest a reduction in the development of sepsis and/or other important sepsis related outcomes. While the laboratory and early clinical experience with statins are encouraging, randomized controlled trials will be need to fully define the role of statins in the prevention and treatment of sepsis.

Statins in sepsis

Sepsis is a common intensive care unit event occurring in approximately 750 000 patients annually, with a case mortality rate approaching 50%. Sepsis is characterized by a chaotic and excessive release of inflammatory cytokines and procoagulants including tumor necrosis factor, interleukin (IL)-1, IL-6, IL-8, platelet-activating factor, and tissue factor. Efforts to inhibit individual cytokines in order to modify poor outcomes have been generally disappointing, suggesting the need to target multiple inflammatory mediators to obtain clinical benefit. Statins lower lipids by inhibiting 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, which in turn inhibits the rate-limiting step in cholesterol biosynthesis. In addition to lowering total cholesterol, statins have pleiotropic effects on inflammation and immunity. Instead of impacting a single entity in the sepsis syndrome, statins may have positive effects on multiple inflammatory, immunomodulating, and coagulation targets involved in the development of infection and sepsis. There have been a number of institutional- and population-based studies that have evaluated the impact of statins in patients with infection and sepsis. Most of these studies, but not all, have demonstrated a number of positive outcomes in patients with statins, including reduction in mortality. Based on these data, statins are a promising therapy in the management of patients with sepsis and warrant larger and more rigorous clinical trials.

Preconditioning methods and mechanisms for preventing the risk of decompression sickness in scuba divers: a review

Scuba divers are at risk of decompression sickness due to the excessive formation of gas bubbles in blood and tissues following ascent, with potentially subsequent neurological injuries. Since nonprovocative dive profiles are no guarantor of protection against this disease, novel means are required for its prevention including predive procedures that could induce more resistance to decompression stress. In this article, we review the recent studies describing the promising preconditioning methods that might operate on the attenuation of bubble formation believed to reduce the occurrence of decompression sickness. The main practical applications are simple and feasible predive measures such as endurance exercise in a warm environment, oral hydration, and normobaric oxygen breathing. Rheological changes affecting tissue perfusion, endothelial adaptation with nitric oxide pathway, up-regulation of cytoprotective proteins, and reduction of preexisting gas nuclei from which bubbles grow could be involved in this protective effect.