Preliminary study of low-dose photodynamic therapy on the oxidative stress response of Cutibacterium acnes.

PURPOSE: The objective of this study was to investigate the influence of photodynamic therapy (PDT) employing different, lower 5-aminolevulinic acid (ALA) dosages on the proliferative activity of Cutibacterium acnes (C. acnes). METHODS: In this in vitro bacterial experiment, we examined the effects of PDT using different doses of ALA (0.05 mmol/L; 0.1 mmol/L; 0.5 mmol/L; 1.0 mmol/L; 2.5 mmol/L). To elucidate the underlying mechanisms, we assessed colony-forming units (CFUs), bacterial staining for live/dead, antioxidant enzyme activity, and gene expression of oxidative stress markers following treatment with different doses of ALA-PDT. RESULTS: Our findings demonstrate that CFU, bacterial staining for live/dead, as well as the activity and gene expression of superoxide dismutase (SOD) and catalase (CAT), all exhibited significant increases when the ALA concentration was 0.1/0.5 mmol/L. However, both CFU and cell growth of C. acnes decreased when the ALA concentration reached 1.0 mmol/L. CONCLUSION: Lower concentration of ALA-PDT (0.1/0.5 mmol/L) appears to promote the growth of C.acnes while higher doses (1.0 /2.5 mmol/L) are associated with eradication. The procedure is possibly mediated by the activation of antioxidant-related genes and enzyme expression in cells.

A Simple HPLC-MS/MS Method for Determination of Tryptophan, Kynurenine and Kynurenic Acid in Human Serum and its Potential for Monitoring Antidepressant Therapy.

The kynurenine pathway, in which tryptophan is metabolized to kynurenine and kynurenic acid, has been linked to depression. A rapid and highly reproducible liquid-chromatography-tandem mass spectrometry (LC-MS/MS) method were established for determining tryptophan, kynurenine and kynurenic acid in human serum. Biological samples were precipitated with methanol before separation on an Agilent Eclipse XDB-C18. The stable-isotope-labeled internal standards (kynurenine-13C415N and kynurenic acid-d5) were used for quantification. Detection was performed using multiple reaction monitoring in electrospray ionization mode at m/z 205.1→188.1 for tryptophan, m/z 209.1→146.1 for kynurenine, m/z 190.1→144.1 for kynurenic acid. Good linearity of analyte to internal standard peak area ratios was seen in the concentration range 1,000-50,000 ng/mL for tryptophan, 100-5,000 ng/mL for kynurenine and 1-60 ng/mL for kynurenic acid. Pooled drug-free human serum was purified using activated charcoal and the method was shown to be linear, with validation parameters within acceptable limits. The newly developed method was successfully used to determine concentrations of tryptophan, kynurenine and kynurenic acid in serum from 26 healthy volunteers and 54 patients with depression. Concentrations of tryptophan and kynurenine were lower in serum from depressed individuals than from healthy individuals.

Reduction of preanalytical errors in clinical laboratory through multiple aspects and whole course intervention measures.

OBJECTIVE: Errors in preanalytical phase decrease the accuracy of reports from clinical laboratory department. Considering the disqualified rate of preanalytical sample in our hospital, we performed several intervention measures to improve the situation. METHODS: The disqualified sample types and major causes of errors in the preanalytical phase were investigated in clinical laboratory department from September 2008 to August 2009. In the following year, we utilized multiple measures to properly intervene the key points of whole sample collection process, and the preanalytical errors were reanalyzed trimonthly, then the disqualification rate of total, major disqualified sample types and different test groups were calculated to evaluate the effects of the intervention measures. RESULTS: The total disqualification rate in the preanalytical phase obtained from September 2008 to August 2009 was 1.36%, and the major types of disqualified samples were coagulation of anticoagulant sample, sample inadequacy, sample container error, sample information error and sample type error. After one year intervention through key points of whole preanalytical sample collection process, the total disqualification rate dropped to 0.94%, and the disqualification rate of coagulation of anticoagulant sample, sample inadequacy, sample container error, sample information error, and sample type error decreased by 20.45%, 28.00%, 25.00%, 76.92%, and 66.66%, respectively. As for test groups, the decreasing amplitude of biochemical, routine, immunological, microbiological and emergency test group was 47.36%, 33.33%, 20.00%, 50.00%, and 21.43%, respectively. CONCLUSIONS: The overall effect of the interventions is very good, and the disqualification rate of the main causes decreases to various degrees.