A blunted sympathetic and accentuated parasympathetic response to postural change in subjects with depressive disorders.

BACKGROUND: In recent years, the bi-directional relationship between depression and ANS dysfunction has received considerable attention, but findings remain inconclusive. In this study, we aimed to examine the spectral HRV response to postural change in subjects with depressive disorders and in healthy controls, in order to gain insight into the characteristics of autonomic nervous system (ANS) response to postural change in subjects with depressive disorders. METHODS: We compared HRV response to postural change between subjects with depressive disorders and healthy controls aged 20-37 years. Depression severity was assessed by the self-reported Beck Depression Inventory-II (BDI-II). Spectral HRV was analyzed at two moments: 10 min seated rest and 10 min at standing position, with spontaneous breathing. RESULTS: No significant differences existed in the resting spectral HRV indices between subjects with depressive disorders and controls, however, following postural change, the increasing level of LF and LF/HF was lower and the decreasing level of HF power was higher, in the individuals with depression than that in healthy subjects. The differences in the LF power, HF power and the LF/HF ratio between seated rest before standing up and after postural change were found negatively correlated with depression severity. CONCLUSION: We found a blunted sympathetic and accentuated parasympathetic response to postural change in subjects with depressive disorder, suggesting that the autonomic impairment and early ANS dysfunction may exist among depressed individuals. These findings indicated that spectral analysis of HRV associated with postural change may be a more sensitive method than resting HRV analysis for detecting ANS dysfunction in depressive disorders. LIMITATIONS: Further studies are needed to expand the sample size and to clarify the mechanisms responsible for the autonomic dysfunction observed in individuals with depressive disorders.

Attenuated or absent HRV response to postural change in subjects with primary insomnia.

Previous studies have compared rest heart rate variability (HRV) between insomniacs and good sleepers, but the results have not been consistent. The altered HRV behavior in response to postural change was considered useful as another sensitive measure for evaluating the autonomic nervous function, however, to our knowledge, no study was found using HRV response to postural change in primary insomnia. Our study aimed to examine HRV response to postural change maneuver (PCM) in both primary insomniacs and controls between 22 and 39 years of age to gain insights into the characteristics of the autonomic nervous system (ANS) function in primary insomnia subjects. HRV was recorded for 5 min at seated rest, and then, the subjects quickly stood up from a seated position in up to 3s and remained standing for 15 min. HRV was recorded at the following times: seated rest and 0-5 min, 5-10 min and 10-15 min in the standing position. In primary insomnia subjects, attenuated or absent HRV response to postural change was identified, the increase in LF/HF ratio and the decrease in HF and SD1 from seated to standing were much slower than in the normal controls. In conclusion, this study provided evidence of the possible bi-directional relationship between insomnia and autonomic nervous system (ANS) function, which will move us closer to developing a new sensitive method for measuring autonomic impairment and early sympathetic damage in primary insomnia subjects.

[Macromolecular aromatic network characteristics of Chinese power coal analyzed by synchronous fluorescence and X-ray diffraction].

Coal structure, especially the macromolecular aromatic skeleton structure, has a strong influence on coke reactivity and coal gasification, so it is the key to grasp the macromolecular aromatic skeleton coal structure for getting the reasonable high efficiency utilization of coal. However, it is difficult to acquire their information due to the complex compositions and structure of coal. It has been found that the macromolecular aromatic network coal structure would be most isolated if small molecular of coal was first extracted. Then the macromolecular aromatic skeleton coal structure would be clearly analyzed by instruments, such as X-ray diffraction (XRD), fluorescence spectroscopy with synchronous mode (Syn-F), Gel permeation chromatography (GPC) etc. Based on the previous results, according to the stepwise fractional liquid extraction, two Chinese typical power coals, PS and HDG, were extracted by silica gel as stationary phase and acetonitrile, tetrahydrofuran (THF), pyridine and 1-methyl-2-pyrollidinone (NMP) as a solvent group for sequential elution. GPC, Syn-F and XRD were applied to investigate molecular mass distribution, condensed aromatic structure and crystal characteristics. The results showed that the size of aromatic layers (La) is small (3-3.95 nm) and the stacking heights (Lc) are 0.8-1.2 nm. The molecular mass distribution of the macromolecular aromatic network structure is between 400 and 1 130 amu, with condensed aromatic numbers of 3-7 in the structure units.