Relationship between reduced nicotinamide adenine dinucleotide phosphate oxidase subunit p22phox gene polymorphism and obstructive sleep apnea-hypopnea syndrome in the Chinese Han population

Background Increased production of reactive oxygen species （ROS） is thought to play a major role in the pathogenesis of obstructive sleep apnea-hypopnea syndrome （OSAHS）. The reduced nicotinamide adenine dinucleotide phosphate （NADPH） oxidase complex is an important source of ROS. The p22phox subunit is polymorphic with a C242T variant that changes histidine-72 for a tyrosine in the potential heme binding site. This study aimed to investigate the relationship between NADPH oxidase subunit p22phox gene polymorphism and OSAHS. Methods The genotypes of p22phox polymorphism were determined by polymerase chain reaction-restriction fragment length polymorphisms （PCR-RFLP） assay in 176 unrelated subjects of the Han population in southern region of China （including 107 OSAHS subjects and 69 non-OSAHS subjects）, while the plasma concentration of superoxide dismutase （SOD） was detected in the two groups, and p22phox mRNA expression in peripheral blood mononuclear cell （PBMC） was determined with reverse transcription polymerase chain reaction （RT-PCR）. Results The phagocyte NADPH oxidase subunit p22phox mRNA expression was significantly increased in the OSAHS group than that in the non-OSAHS group （P 〈0.01）. Compared with the non-OSAHS control group （（85.31±9.23） U/ml）, the levels of SOD were lower in patients with OSAHS （（59.65±11.61） U/ml （P 〈0.01）. There were significant differences in genotypes distribution in p22phox polymorphism between the two groups （P=0.02）. Compared with the non-OSAHS control group, the OSAHS group had a significantly higher T allele frequency in p22phox polymorphism （P=0.03）. There were independent effects of p22phox polymorphism on body mass index （BMI）, neck circumference （NC）, waist-to-hip ratio （WHR） in the OSAHS group, and the carriers of the T allele of p22phox polymorphism had greater NC, WHR, systolic blood pressure （SBP）, diastolic blood pressure （DBP） and apnea-hypopnea index （AHI） （P 〈0.05）, but the carriers of the T allele had lower SOD （P 〈0.01） and lowest SaO2 （P=0.04）. There was no significant difference in p22phox mRNA expression between the OSAHS groups with or without T allele （P=0.45）. Conclusions The NADPH oxidase subunit p22phox gene polymorphism may be associated with susceptibility to OSAHS, and it may be an important candidate gene for OSAHS.

Dynamic Non-Invasive Detection of NADH Based on Blood Flow-Mediated Skin Fluorescence (FMSF) Method

Nicotinamide adenine dinucleotide (NADH/NAD+) is involved in important biochemical reactions in human metabolism, including participation in energy production by mitochondria. The changes in fluorescence intensity as a function of time in response to blocking and releasing of blood flow in a forearm are used as a measure of oxygen transport with blood to the tissue, which directly correlates with the skin microcirculation status. In this paper, a non-invasive dynamic monitoring system based on blood flow-mediated skin fluorescence (FMSF) technology is developed to monitor the NADH fluorescence intensity of skin tissue during the process of blocking reactive hyperemia. Simultaneously, laser speckle contrast imaging (LSCI) and laser Doppler flowmetry (LDF) were used to observe blood flow, blood oxygen saturation (SOt2) and relative amount of hemoglobin (rHb) during the measurement process, which helped to explore NADH dynamics relevant physiological changes. A variety of parameters have been derived to describe NADH fluorescence curve based on the FMSF device. The experimental results are conducive to understanding the NADH measurement and the physiological processes related to it, which help FMSF to be a great avenue for in vivo physiological, clinical and pharmacological research on mitochondrial metabolism.

MITOCHONDRIAL REDOX IMAGING FOR CANCER DIAGNOSTIC AND THERAPEUTIC STUDIES

Mitochondrial redox states provide important information about energy-linked biological processes and signaling events in tissues for various disease phenotypes including cancer.The redox scanning method developed at the Chance laboratory about 30 years ago has allowed 3D highresolution(∼50×50×10µm^(3))imaging of mitochondrial redox state in tissue on the basis of the fluorescence of NADH(reduced nicotinamide adenine dinucleotide)and Fp(oxidized flavoproteins including flavin adenine dinucleotide,i.e.,FAD).In this review,we illustrate its basic principles,recent technical developments,and biomedical applications to cancer diagnostic and therapeutic studies in small animal models.Recently developed calibration procedures for the redox imaging using reference standards allow quantification of nominal NADH and Fp concentrations,and the concentration-based redox ratios,e.g.,Fp/(Fp+NADH)and NADH/(Fp+NADH)in tissues.This calibration facilitates the comparison of redox imaging results acquired for different metabolic states at different times and/or with different instrumental settings.A redox imager using a CCD detector has been developed to acquire 3D images faster and with a higher in-plane resolution down to 10µm.Ex vivo imaging and in vivo imaging of tissue mitochondrial redox status have been demonstrated with the CCD imager.Applications of tissue redox imaging in small animal cancer models include metabolic imaging of glioma and myc-induced mouse mammary tumors,predicting the metastatic potentials of human melanoma and breast cancer mouse xenografts,differentiating precancerous and normal tissues,and monitoring the tumor treatment response to photodynamic therapy.Possible future directions for the development of redox imaging are also discussed.

Noninvasive in vivo study of NADH fluorescence and its real-time intrinsic dynamical changes: Experiments and seven-layered skin model Monte Carlo simulations

Reduced nicotinamide adenine dinucleotide(NADH)plays a crucial role in many biochemical reactions in human metabolism.In this work,a flow-mediated skin fluorescence(FMSF)-postocclusion reactive hyperaemia(PORH)system was developed for noninvasive and in vivo measurement of NADH fluorescence and its real-time dynamical changes in human skin tissue.The real-time dynamical changes of NADH fluorescence were analyzed with the changes of skin blood flow measured by laser speckle contrast imaging(LSCI)experiments simultaneously with FMSFPORH measurements,which suggests that the dynamical changes of NADH fluorescence would be mainly correlated with the intrinsic changes of NADH level in the skin tissue.In addition,Monte Carlo simulations were applied to understand the impact of optical property changes on the dynamical changes of NADH fluorescence during the PORH process,which further supports that the dynamical changes of NADH fluorescence measured in our system would be intrinsic changes of NADH level in the skin tissue.

FLIM as a Promising Tool for Cancer Diagnosis and Treatment Monitoring

Fluorescence lifetime imaging microscopy(FLIM)has been rapidly developed over the past 30 years and widely applied in biomedical engineering.Recent progress in fluorophore-dyed probe design has widened the application prospects of fluorescence.Because fluorescence lifetime is sensitive to microenvironments and molecule alterations,FLIM is promising for the detection of pathological conditions.Current cancer-related FLIM applications can be divided into three main categories:(i)FLIM with autofluorescence molecules in or out of a cell,especially with reduced form of nicotinamide adenine dinucleotide,and flavin adenine dinucleotide for cellular metabolism research;(ii)FLIM with Förster resonance energy transfer for monitoring protein interactions;and(iii)FLIM with fluorophore-dyed probes for specific aberration detection.Advancements in nanomaterial production and efficient calculation systems,as well as novel cancer biomarker discoveries,have promoted FLIM optimization,offering more opportunities for medical research and applications to cancer diagnosis and treatment monitoring.This review summarizes cutting-edge researches from 2015 to 2020 on cancer-related FLIM applications and the potential of FLIM for future cancer diagnosis methods and anti-cancer therapy development.We also highlight current challenges and provide perspectives for further investigation.