Nitric Oxide in Fungi: Production and Function

Nitric oxide (NO) is synthesized in all kingdoms of life, where it plays a role in the regulation of various physiological and developmental processes. In terms of endogenous NO biology, fungi have been less well researched than mammals, plants, and bacteria. In this review, we summarize and discuss the studies to date on intracellular NO biosynthesis and function in fungi. Two mechanisms for NO biosynthesis, NO synthase (NOS)-mediated arginine oxidation and nitrate- and nitrite-reductase-mediated nitrite reduction, are the most frequently reported. Furthermore, we summarize the multifaceted functions of NO in fungi as well as its role as a signaling molecule in fungal growth regulation, development, abiotic stress, virulence regulation, and metabolism. Finally, we present potential directions for future research on fungal NO biology.

Comparative Economic Analysis Between Endogenous and Recombinant Production of Hyaluronic Acid

Hyaluronic acid (HA) is a biopolymer with a wide range of applications, mainly in the cosmetic and pharmaceutical sectors. Typical industrial-scale production utilizes organisms that generate HA during their developmental cycle, such as Streptococcus equi sub. zooepidemicus. However, a significant disadvantage of using Streptococcus equi sub. zooepidemicus is that it is a zoonotic pathogen, which use at industrial scale can create several risks. This creates opportunities for heterologous, or recombinant, production of HA. At an industrial scale, the recovery and purification of HA follow a series of precipitation and filtration steps. Current recombinant approaches are developing promising alternatives, although their industrial implementation has yet to be adequately assessed. The present study aims to create a theoretical framework to forecast the advantages and disadvantages of endogenous and recombinant strains in production with the same downstream strategy. The analyses included a selection of the best cost-related recombinant and endogenous production strategies, followed by a sensitivity analysis of different production variables in order to identify the three most critical parameters. Then, all variables were analyzed by varying them simultaneously and employing multiple linear regression. Results indicate that, regardless of HA source, production titer, recovery yield and bioreactor scale are the parameters that affect production costs the most. Current results indicate that recombinant production needs to improve current titer at least 2-fold in order to compete with costs of endogenous production. This study serves as a platform to inform decision-making for future developments and improvements in the recombinant production of HA.

Interaction between hydrogen sulfide, nitric oxide, and carbon monoxide pathways in the bovine isolated retina

Purpose

Nitric oxide (NO), carbon monoxide (CO) and hydrogen sulfide (H₂S) are physiologically relevant gaseous neurotransmitters that are endogenously produced in mammalian tissues. In the present study, we investigated the possibility that NO and CO can regulate the endogenous levels of H₂S in bovine isolated neural retina.

Methods

Isolated bovine neural retina were homogenized and tissue homogenates were treated with a NO synthase inhibitor, NO donor, heme oxygenase-1 inhibitor, and/donor. H₂S concentrations in bovine retinal homogenates were measured using a well-established colorimetric assay.

Results

L-NAME (300 nM–500 µM) caused a concentration-dependent decrease in basal endogenous levels of H₂S by 86.2%. On the other hand, SNP (10–300 µM) elicited a concentration-related increase in H₂S levels from 18.3 nM/mg of protein to 65.7 nM/mg of protein. ZnPP-IX (300 nM–10 µM) caused a concentration-dependent increase in the endogenous production of H₂S whereas hemin (300 nM–20 µM) attenuated the basal levels of H₂S.

Conclusion

We conclude that changes in the biosynthesis and availability of both NO and CO can interfere with the pathway/s involved in the production of H₂S in the retina. The demonstrated ability of NO, CO and H₂S to interact in the mammalian retina affirms a physiological/pharmacological role for these gaseous mediators in the eye.

Measurements of the optical coefficients of the protoporphyrin IX endogenously producing yeast-based model in the visible and NIR

Models mimicking the endogenous production of protoporphyrin IX (PpIX), as well as its fluorescence, are of high interest for applied and fundamental studies in the fields of cancer detection by fluorescence imaging, photodynamic therapy (PDT), and photobiomodulation (PBM). Here, we present and describe optical properties of the yeast-based models able to produce PpIX endogenously after the administration of 5-aminolevulinic acid (ALA) and/or 2,2'-bipyridyl. As their optical properties have an important impact on the spatial distribution of the fluence rate in these liquid models, their absorption and reduced scattering coefficients were determined to be between 400 and 808 nm for two yeast solutions previously described by our group. These coefficients were derived from measurements of the total reflectance and light penetration depth using a dedicated Monte Carlo simulation. We observed that absorption and scattering coefficients were smaller than those of soft tissues at all wavelengths. This work will enable the production of a low-cost optical phantom loaded with appropriate amounts of light-absorbing and -scattering particles to mimic tumors containing PpIX, offering a useful tool to optimize the spectral and radiometric design of certain cancer photodetection setups.

1α,25-dihydroxyvitamin D3-eluting nanofibrous dressings induce endogenous antimicrobial peptide expression

AIM

The aim of this study was to develop a nanofiber-based dressing capable of local sustained delivery of 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3) and augmenting human CAMP induction.

MATERIALS & METHODS

Nanofibrous wound dressings containing 1,25(OH)2D3 were successfully prepared by electrospinning, which were examined in vitro, in vivo and ex vivo.

RESULTS

1,25(OH)2D3 was successfully loaded into nanofibers with encapsulation efficiency larger than 90%. 1,25(OH)2D3 showed a sustained release from nanofibers over 4 weeks. Treatment of U937 and HaCaT cells with 1,25(OH)2D3-loaded poly(ϵ-caprolactone) nanofibers significantly induced hCAP18/LL37 expression in monocytes and keratinocytes, skin wounds of humanized transgenic mice and artificial wounds of human skin explants.

CONCLUSION

1,25(OH)2D3 containing nanofibrous dressings could enhance innate immunity by inducing antimicrobial peptide production.

Pharmacokinetic analysis of subcutaneous erythropoietin administration with nonlinear mixed effect model including endogenous production

AIMS

Erythropoietin, a glycoprotein hormone is produced by the kidney and targeted to erythrocyte precursors. Recombinant human erythropoietin (Epoetin beta) has been utilized for therapeutic purposes in renal anaemia or anaemia occurring after auto blood donation or chemotherapy. The administration routes for erythropoietin are normally subcutaneous or intravenous. No population pharmacokinetic analysis, however, has been performed following subcutaneous administration with consideration given for endogenous production.

METHODS

In the present study, we have attempted to analyze the pharmacokinetics of erythropoietin after subcutaneous administration in healthy adult male volunteers by using the Nonlinear Mixed Effect Model program (NONMEM) with a model including endogenous erythropoietin production.

RESULTS

It has been established that the final estimation of the population mean values of the absorption rate constant (ka), the elimination rate constant (ke), the distribution volume (V) and the endogenous production are 0.0430 h(-1), 0.206 h(-1), 3.141 and 15.7IU h(-1), respectively. For the circadian rhythm of endogenous production, the amplitude was calculated as 9.86% and the peak appeared around 24.00 h.

CONCLUSIONS

The values for ke and V are very similar to those previously reported for intravenous administration. The circadian rhythm of endogenous production are also able to be substantiated. The factors influencing ke were found to be serum creatinine and age.