Local administration of nitric oxide donor significantly impacts microvascular thrombosis

Leech Therapy Protects Free Flaps against Venous Congestion, Thrombus Formation, and Ischemia/Reperfusion Injury: Benefits, Complications, and Contradictions

The use of free cutaneous or myocutaneous flaps in some surgeries, especially in reconstructive surgeries, is routine and imperative; nevertheless, it is controversial because of fear of flap loss due to tissue congestion and partial or complete necrosis. Different mechanisms are discussed in this process, and based on the involved mechanisms, various agents and approaches are suggested for flap salvage. Among these agents and strategies, leech therapy (hirudotherapy) can be a valuable complementary treatment; however, in this way, full attention should be given to all beneficial and harmful aspects to reach the best results. This study included a literature review of the essential complications following free tissue transfer and explained the effects of leech therapy for the respective complications. Based on the review of the literature, the essential complications following free tissue transfer were (I) venous obstruction and congestion, (II) delay in blood flow reestablishment, (III) ischemia/reperfusion injuries, and (IV) thrombus formation. Leech therapy can protect free flaps against the mentioned complications as a complementary treatment. Leech therapy is an appropriate complement, however, not a definite approach for flap salvage. Therefore, in some patients, other alternative methods or even flap removal may be a better option.

Protein disulfide isomerase regulation by nitric oxide maintains vascular quiescence and controls thrombus formation

Essentials Nitric oxide synthesis controls protein disulfide isomerase (PDI) function. Nitric oxide (NO) modulation of PDI controls endothelial thrombogenicity. S-nitrosylated PDI inhibits platelet function and thrombosis. Nitric oxide maintains vascular quiescence in part through inhibition of PDI. SUMMARY: Background Protein disulfide isomerase (PDI) plays an essential role in thrombus formation, and PDI inhibition is being evaluated clinically as a novel anticoagulant strategy. However, little is known about the regulation of PDI in the vasculature. Thiols within the catalytic motif of PDI are essential for its role in thrombosis. These same thiols bind nitric oxide (NO), which is a potent regulator of vessel function. To determine whether regulation of PDI represents a mechanism by which NO controls vascular quiescence, we evaluated the effect of NO on PDI function in endothelial cells and platelets, and thrombus formation in vivo. Aim To assess the effect of S-nitrosylation on the regulation of PDI and other thiol isomerases in the vasculature. Methods and results The role of endogenous NO in PDI activity was evaluated by incubating endothelium with an NO scavenger, which resulted in exposure of free thiols, increased thiol isomerase activity, and enhanced thrombin generation on the cell membrane. Conversely, exposure of endothelium to NO+ carriers or elevation of endogenous NO levels by induction of NO synthesis resulted in S-nitrosylation of PDI and decreased surface thiol reductase activity. S-nitrosylation of platelet PDI inhibited its reductase activity, and S-nitrosylated PDI interfered with platelet aggregation, α-granule release, and thrombin generation on platelets. S-nitrosylated PDI also blocked laser-induced thrombus formation when infused into mice. S-nitrosylated ERp5 and ERp57 were found to have similar inhibitory activity. Conclusions These studies identify NO as a critical regulator of vascular PDI, and show that regulation of PDI function is an important mechanism by which NO maintains vascular quiescence.

Fungal heat-shock proteins in human disease

Heat-shock proteins (hsps) have been identified as molecular chaperones conserved between microbes and man and grouped by their molecular mass and high degree of amino acid homology. This article reviews the major hsps of Saccharomyces cerevisiae, their interactions with trehalose, the effect of fermentation and the role of the heat-shock factor. Information derived from this model, as well as from Neurospora crassa and Achlya ambisexualis, helps in understanding the importance of hsps in the pathogenic fungi, Candida albicans, Cryptococcus neoformans, Aspergillus spp., Histoplasma capsulatum, Paracoccidioides brasiliensis, Trichophyton rubrum, Phycomyces blakesleeanus, Fusarium oxysporum, Coccidioides immitis and Pneumocystis jiroveci. This has been matched with proteomic and genomic information examining hsp expression in response to noxious stimuli. Fungal hsp90 has been identified as a target for immunotherapy by a genetically recombinant antibody. The concept of combining this antibody fragment with an antifungal drug for treating life-threatening fungal infection and the potential interactions with human and microbial hsp90 and nitric oxide is discussed.

Nitric oxide modulation of early angiogenesis

Angiogenesis is the process of new vessel formation from an existing vasculature network. In all but a few circumstances it is tightly controlled and suppressed. Precise understanding of the factors involved in modulation of angiogenesis has significant potential clinical value. One agent believed to play a role in angiogenesis is nitric oxide. However, there remain substantial uncertainties concerning the specifics of this role. The present study was undertaken to better define the role nitric oxide plays in angiogenesis associated with acute wound healing. Muscle biopsies from the pectoralis major of C57B6 mice were embedded in 500 microl of type I collagen matrix, and incubated in the presence of growth medium for 14 days. Treatment wells received L-Arginine (2 mM), L-NAME (300 microM), or SNAP (10-20 microM). Angiogenic response was quantified as the measure of cell migration through the matrix and as the total cells recovered from the matrix. Whole lung specimens and aortic segments served as sources of endothelial and vascular smooth muscle cells respectively for proliferation studies under similar treatment conditions. Nitric oxide was found to exert either a stimulatory or inhibitory effect on angiogenesis and cell proliferation that was subject to the assay system and specific vascular cell types present. These results suggest that the role of nitric oxide in angiogenesis is context dependent.