[Advances in research on impaired ventilatory efficiency in cardiopulmonary exercise testing and chronic obstructive pulmonary disease].

The investigation of the pathophysiological mechanisms and potential applications of impaired ventilatory efficiency in cardiopulmonary exercise testing has received considerable attention in the field of chronic obstructive pulmonary disease (COPD) research worldwide. A growing body of evidence supports the notion that impaired ventilatory efficiency is an important indicator of exertional dyspnea, reduced exercise capacity, and mortality in patients with COPD. As a result, ventilatory efficiency is emerging as a promising therapeutic target for alleviating dyspnea in COPD patients. This review aims to provide a comprehensive summary of the research progress into impaired ventilatory efficiency in patients with COPD. The primary objective of this review is to improve the understanding of COPD patients with impaired ventilatory efficiency, with the ultimate goal of facilitating the comprehensive assessment and management of COPD.

[Progress in pre-chronic obstructive pulmonary disease].

Pre-chronic obstructive pulmonary disease (Pre-COPD) refers to individuals with chronic respiratory symptoms, structural abnormalities, and/or functional abnormalities, in the absence of airflow limitation, who may develop persistent airflow limitation over time. COPD is characterized by high prevalence and great heterogeneity and complexity. Early multidimensional identification and promotion of early prevention, management and treatment of Pre-COPD can help delay or halt the development of COPD, which has significant public health implications. This review aimed to summarize the definition, relevant cohorts, clinical trials, and other research progress in pre-COPD in order to improve the understanding of individuals with pre-COPD and improve early prevention and management of COPD.

Parametric studies on the phase shift method to measure the blood perfusion of biological bodies.

To better understand the phase shift method to non-invasively measure the blood perfusion of living tissues in vivo, the dual reciprocity boundary element method (DRBEM) was applied to numerically solve the transient and non-linear two-dimensional bio-heat transfer in biological bodies subject to a sinusoidal heat flux at the skin surface. The influences of the heating flux, the heating oscillation magnitude, the heating frequency, the blood vessel underneath the skin, and the space or temperature dependent blood perfusion to the temperature response and the phase shift between the heat flux and the temperature response at the skin surface were comprehensively examined. The effects of the heating area to the temperature response were also investigated. And a better understanding on the heat transfer behavior of biological bodies under sinusoidal heating was thus obtained. These results are expected to be valuable for constructing the practical instrumentation to non-invasively measure the blood perfusion of biological bodies.

[Protective effect of ischemic preconditioning on ischemia-reperfusion injury].

OBJECTIVE: To study the protective effect of ischemic preconditioning(IP) on ischemia-reperfusion injury of limb. METHODS: One to three times of short-term ischemia was applicated before prolonged ischemia, a series of biological examinations, including creatine phosphate kinase(CPK), glutamic-oxalacetic transaminase(GOT), lactic dehydrogenase(LDH), malondiadehyde(MDA) and superoxide dismutase(SOD) were carried out in each group. RESULTS: Compared with the control, release of skeletal muscle intracellular enzyme(CPK, GOT and LDH) decreased in experiment groups after preconditioning had been performed. The serum concentration of MDA was lower, activity of SOD was higher, and pathological lesion was less in preconditioning groups than that in non-preconditioning group. Different frequency of preconditioning led to different results. CONCLUSIONS: Preconditioning has protective effect on ischemia-reperfusion injury of limbs, and the effect of IP is correlated with the number of preconditioning cycles.

Biochemical and physicochemical characterization of normal and variant forms of human MTH1 protein with antimutagenic activity.

8-Oxo-7,8-dihydro-2'-deoxyguanosine 5'-triphosphate (8-oxo-dGTP) is produced during cellular metabolism, and its misincorporation into DNA causes mutation. Human cells possess an enzyme that hydrolyzes 8-oxo-dGTP to the corresponding nucleoside monophosphate, thereby preventing misincorporation of 8-oxo-7,8-dihydroguanine into DNA. Sequence analyses of the MTH1 gene, encoding the 8-oxo-7,8-dihydro-2'-deoxyguanosine 5'-triphosphatase (8-oxo-dGTPase) protein in human cell lines revealed that a G to A base substitution frequently occurs at codon 83, which causes a change of valine to methionine in the MTH1 protein [Wu, C. et al., Biochem. Biophys. Res. Commun. 214 (1995) 1239-1245]. Here we isolated cDNAs for the two types of MTH1 protein and expressed them in Escherichia coli mutT-. cells, devoid of their own 8-oxo-dGTPase activity. The two forms of proteins were purified to physical homogeneity, and amino acid analyses confirmed that the variant protein, Met83-MTH1, indeed carries the corresponding amino acid substitution. Met83-MTH1, but not normal type Val83-MTH1, was separated into two peaks in hydrophobic interacting chromatography. 8-Oxo-dGTPase activity of Met83-MTH1 is more thermolabile than that of Val83-MTH1. Circular dichroism (CD) and fluorescence spectroscopic analyses confirmed this conclusion. CD further indicated that Met83-MTH1 has a higher alpha-helix content.