Successful Vancomycin Dose Adjustment in a Sepsis patient with Bacterial Meningitis Using Cystatin C.

Cystatin C-guided vancomycin (VCM) dosing is useful in critically ill patients. Its usefulness in septic patients with bacterial meningitis remains unknown, as there are no published reports. In this study, we sought to clarify its benefit. Cystatin C was used to guide VCM dosing in a septic bacterial meningitis patient with normal kidney function, according to therapeutic drug monitoring (TDM). Using cystatin C, the Bayesian method-based TDM made optimal VCM dosing possible, and decreased the predicted error (4.85 mg/L) compared to serum creatinine (16.83 mg/L). We concluded TDM of VCM using cystatin C can be considered in sepsis patients with bacterial meningitis with normal kidney function.

Quantitative determination of polysulfide in albumins, plasma proteins and biological fluid samples using a novel combined assays approach.

Hydrogen sulfide (H2S) signaling involves polysulfide (RSSnSR') formation on various proteins. However, the current lack of sensitive polysulfide detection assays poses methodological challenges for understanding sulfane sulfur homeostasis and signaling. We developed a novel combined assay by modifying Sulfide Antioxidant Buffer (SAOB) to produce an "Elimination Method of Sulfide from Polysulfide" (EMSP) treatment solution that liberates sulfide, followed with methylene blue (MB) sulfide detection assay. The combined EMSP-MB sulfide detection assay performed on low molecular weight sulfur species showed that sulfide was produced from trisulfide compounds such as glutathione trisulfide and diallyl trisulfide, but not from the thiol compounds such as cysteine, cystine and glutathione. In the case of plasma proteins, this novel combined detection assay revealed that approximately 14.7, 1.7, 3.9, 3.7 sulfide mol/mol released from human serum albumin, α1-anti-trypsin, α1-acid glycoprotein and ovalbumin, respectively, suggesting that serum albumin is a major pool of polysulfide in human blood circulation. Taken together with the results of albumins of different species, the liberated sulfide has a good correlation with cysteine instead of methionine, indicating the site of incorporation of polysulfide is cysteine. With this novel sulfide detention assay, approximately 8,000, 120 and 1100 µM of polysulfide concentrations was quantitated in human healthy plasma, saliva and tear, respectively. Our promising polysulfide specific detection assay can be a very important tool because quantitative determination of polysulfide sheds light on the functional consequence of protein-bound cysteine polysulfide and expands the research area of reactive oxygen to reactive polysulfide species.

Human serum albumin hydropersulfide is a potent reactive oxygen species scavenger in oxidative stress conditions such as chronic kidney disease.

Recently, hydropersulfide (RSSH) was found to exist in mammalian tissues and fluids. Cysteine hydropersulfide can be found in free cysteine residues as well as in proteins, and it has potent antioxidative activity. Human serum albumin (HSA) is the most abundant protein in mammalian serum. HSA possesses a free thiol group in Cys-34 that could be a site for hydropersulfide formation. HSA hydropersulfide of high purity as a positive control was prepared by treatment of HSA with Na2S. The presence of HSA hydropersulfide was confirmed by spectroscopy and ESI-TOFMS analysis where molecular weights of HSA hydropersulfide by increments of approximately 32 Da (Sulfur atom) were detected. The fluorescent probe results showed that Alexa Fluor 680 conjugated maleimide (Red-Mal) was a suitable assay and bromotrimethylammoniumbimane bromide appeared to be a selective reagent for hydropersulfide. The effect of oxidative stress related disease on the existence of albumin hydropersulfides was examined in rat 5/6 nephrectomy model of chronic kidney disease (CKD). Interestingly, the level of hydropersulfides in rat 5/6 nephrectomy model serum was decreased by a uremic toxin that increases oxidative stress in rat 5/6 nephrectomy model. Furthermore, we demonstrated that the levels of HSA hydropersulfide in human subjects were reduced in CKD but restored by hemodialysis using Red-Mal assay. We conclude that HSA hydropersulfide could potentially play an important role in biological anti-oxidative defense, and it is a promising diagnostic and therapeutic marker of oxidative diseases.