Influencing factors of resource utilisation in haemodialysis patients-Based on socioecological pyramid model.

AIMS AND OBJECTIVES: To describe the current situation and analyse influencing factors of resource utilisation in maintenance haemodialysis patients. BACKGROUND: The self-management level of patients undergoing maintenance haemodialysis in China is low. The applicability of the Chronic Illness Resources Survey in Chinese maintenance haemodialysis patients has been validated, and this survey can be used to assess the utilisation of self-management support resources among haemodialysis patients. Determining the influencing factors of resource utilisation can help improve the self-management behaviour of haemodialysis patients and control the progression of the disease. DESIGN: A descriptive study design was chosen. METHODS: A convenience sample of 314 patients undergoing haemodialysis was recruited from dialysis centres in three hospitals in western Xinjiang from June 2018-April 2019. SPSS19.0 software was used to describe the current situation of resource utilisation. Moreover, t test, analysis of variance and multivariate linear regression were applied to explore the influencing factors of patients' resource utilisation. Standards for observational studies STROBE Statement checklist-v4 were chosen on reporting the study process. RESULTS: The average score of the total resource utilisation was 2.95 ± 0.51. The average item score of seven dimensions from high to low was 3.46 for medical staff, 3.32 for personal, 3.22 for family and friends, 3.16 for work-related, 3.12 for media policy, 2.55 for neighbourhood/community and 2.23 for organisation. Multiple linear regression showed that there have six main factors, which explained 65.4% of the variance of haemodialysis patients' resource utilisation. CONCLUSIONS: The personal, family and friends, work and media and policy subscales were rated the highest, with support from neighbourhood/community and organisation rated the lowest. In general, participants perceived moderate levels of support. Government and healthcare team should pay more attention on haemodialysis patients who had low level of education, poor economic conditions and poor mental condition. RELEVANCE TO CLINICAL PRACTICE: ESRD has caused a burden on healthcare expenditure and has become a critical public health problem worldwide. Self-management is particularly important for dialysis patients which have attracted extensive interest. In the future research, we can use this questionnaire to evaluate the related resources of disease management of dialysis patients, encourage patients to make full use of the resources around them and focus on those patients with low education and monthly income level and bad mental state.

Pmma-XO (X = C, Si, Ge) monolayer as promising anchoring materials for lithium-sulfur battery: a first-principles study.

Lithium-sulfur (Li-S) batteries hold great promise for the next-generation lithium-ion energy storage devices. A key issue in the Li-S batteries is, however, the dissolving and migrating of the soluble polysulfides during the charge and discharge processes and introducing anchoring materials (AM) in the batteries effectively prevent the problem and improve the cycling stability of the Li-S batteries. Herein, Pmma-XO (X = C, Si, Ge, Sn) monolayers are introduced as AM to confine the lithium polysulfides and their anchoring properties are studied with the density functional theory methods. Particularly, Pmma-SiO and GeO monolayers are studied for the first time, and our calculations show that these two materials are stable semiconductive monolayers with direct-band-gaps and moderate binding with lithium polysulfides Li2S n (n = 8, 6, 4, 2 and 1). The Pmma-SiO and GeO trap Li2S n species on their surfaces and keep them intact during the charge and discharge, and the adsorption of Li2S n species leads to the enhanced conductivity of Pmma-SiO and GeO monolayers. Our study suggests that the Pmma-SiO and GeO monolayers are the promising AM for highly efficient Li-S batteries.

Pedobacter chitinilyticus sp. nov., a chitin-degrading bacterium isolated from wheat leaf tissue.

A bacterium, designated strain CM134L-2T, was isolated from a chitin-enriched wheat leaf microbiome in Chengdu, Sichuan province, China. It was Gram-stain-negative, strictly aerobic, non-spore-forming, motile, rod-shaped, and bright yellow in colour. Strain CM134L-2T grew at 4-35 °C, at pH 6.0-9.0 and could use chitin as the only carbon resource. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain CM134L-2T was most closely related to Pedobacter nanyangensis Q-4T (97.7 %) and Pedobacter zeaxanthinifaciens TDMA-5T (97.4 %). Digital DNA-DNA hybridization (dDDH) values between strain CM134L-2T with these two type strains were 26.8  and 20.8 %, respectively, and average nucleotide identity (ANI) values were 83.2 and 76.2 %; these values are lower than the proposed and generally accepted species boundaries of 70 % for dDDH and 95-96 % for ANI, which suggests strain CM134L-2T represents a novel species. The genomic DNA G+C content of strain CM134L-2T was 39.3 mol%, menaquinone-7 was the major respiratory quinone, phosphatidylethanolamine was the major polar lipid and the major components of the cellular fatty acids were iso-C15 : 0, and C16 : 1ω7c/C16 : 1ω6c (summed feature 3); these features supported the affiliation of strain CM134L-2T to the genus Pedobacter. Overall, strain CM134L-2T belongs to the genus Pedobacter, but can be classified as a novel species, for which the name Pedobacter chitinilyticus sp. nov. is proposed. The type strain is CM134L-2T (=CGMCC 1.16520T=KCTC 62643T).

Molecular characterization of a hepcidin homologue in starry flounder (Platichthys stellatus) and its synergistic interaction with antibiotics.

Hepcidins are small cysteine-rich antimicrobial peptides that play an important role in host immunity against pathogenic organisms. Most fish hepcidins exert bactericidal activities against a wide range of pathogens. In this study, we identified a cDNA sequence encoding a hepcidin homologue (PsHepcidin) in the starry flounder Platichthys stellatus. The predicted amino acid sequence of PsHepcidin comprises a signal peptide and a prodomain, which are followed by the mature peptide. Sequence analysis revealed that PsHepcidin belongs to the fish HAMP2 cluster and that it is closely related to mudskipper hepcidin-2. Expression of PsHepcidin mRNA was detected in all examined immune-related tissues, with the highest transcript levels being found in the liver. In response to lipopolysaccharide treatment, PsHepcidin was significantly up-regulated in the liver, kidney, and spleen in a time-dependent manner. Chemically synthesized mature peptides of PsHepcidin were found to exhibit broad antimicrobial activity in vitro. We also investigated the combined effect of PsHepcidin and conventional antibiotics and found that these combinations showed synergistic effects against most of the examined bacterial strains. Collectively, the results of this study indicate that PsHepcidin exhibits potent antibacterial activity both independently and when used in combination with conventional antibiotics.

Nanopolygons of Monolayer MS2: Best Morphology and Size for HER Catalysis.

With first-principles calculations, we find a new strategy for developing high-performance catalysts for hydrogen evolution reaction (HER) via controlling the morphology and size of nanopolygons of monolayer transition-metal dichalcogenides (npm-MS2, with M = Mo, W, or V). Particularly, through devising a quantitative method to measure HER-active sites per unit mass and using such HER site density to comparatively gauge npm-MS2 performance, we identify three keys in making npm-MS2 with optimal HER performance: (a) npm-MS2 should be triangular with each edge being M-terminated and each edge-M atom passivated by one S atom; (b) each edge of npm-MoS2 and WS2 should have 5-6 metal atoms as HER site density drops below/above these sizes optimal both for HER and practical npm growth; and (c) npm-VS2 is immune to this overly fastidious size dependence. Known experimental data on npm-MoS2 indeed support the plausibility of practicing these design rules. We expect that raising the nucleation density and controlling the growth time to favor the production of our proposed ultrasmall npm-MS2 are critical but practical. Research on npm-VS2 would bear the highest impact because of its size-forgiving HER performance and relatively high abundance and low cost.

First-principles investigations of transition-metal doped bilayer WS2.

By performing first-principles calculations, we have studied the structural, electronic and magnetic properties of transition-metal (TM) (Mn, Fe, Co, Ni) doped bilayer WS2 in both the AA and AB configurations. We have examined three probable interlayer doping positions, and found that the doped TM atoms prefer to stay below the S atoms. The TM atoms are covalently bound to the upper layer and lower layer S atoms with binding energies ranging from -0.74 to -1.72 eV for the AA configuration and from -0.69 to -1.80 eV for the AB configuration. Our calculations indicate that all the studied configurations are still semiconductors although the corresponding band gaps reduce a lot, except for the Fe-doped AA configuration which changes to a semi-metal with one spin state cross over at the Fermi level. Additional, our calculations indicate that Mn, Fe and Co-doping induces magnetism in both the AA and AB configurations. More importantly, a high spin polarization of 100% at the Fermi level is achieved in the Co-doped AA configuration and the Mn and Fe-doped AB configurations, which implies the potential for application in spintronic devices.

[Clinical Characteristics of Wilson's Disease: a Retrospective Analysis of Admission Data among 126 Patients].

OBJECTIVE: To investigate the clinical features of Wilson's disease (WD) for the purpose of avoiding misdiagnosis and therefore improving the prognosis of this rare disease. METHODS: This study enrolled all the patients diagnosed as WD who were admitted to West China Hospital, Sichuan University from Jan 2008 to Dec 2014. Their clinical manifestations, head and abdominal images data were extracted and analyzed. RESULTS: There were a total of 126 patients of WD, male female ratio was 75 : 51, median age was 21-years old. 10.3% (13/126) of them had family history, 87.3% (109/126) patients presented with neuropsychiatric symptoms, 14.3% (18/126) patients manifested as chronic liver disease. All patients had decreased serum ceruloplasmin level < 200 mg/L, 121 (96.9%) patients had serum ceruloplasmin level < 100 mg/L. Magnetic resonance imaging and abdominal ultrasound detected structural abnormalities in 92.7% (102/110) and 88.9% (97/109) patients respectively. Kayser-Fleischer rings on slit-lamp ophthalmologic examination was found in 98.3% (115/117) patients. One patient underwent liver biopsy and the result of rhodanine stain was positive. The time from onset to diagnosis varied from 3 d to 19 years [(1.59 ± 2.66) years]. 20 (15.9%) patients were initially misdiagnosed. CONCLUSION: The patients presenting with neurological signs or unexplained liver disease should be assessed carefully for WD. Serum ceruloplasmin, 24-h urinary copper, Kayser-Fleischer rings and sometimes even liver biopsy could be helpful for the diagnosis.

Influence of intramuscular heat stimulation on modulation of nociception: complex role of central opioid receptors in descending facilitation and inhibition.

It has been reported that the threshold to activate 'silent' or inactive descending facilitation of nociception is lower than that of descending inhibition. Thus, the development of pain therapy to effectively drive descending inhibition alone, without the confounding influences of facilitation is a challenge. To address this issue we investigated the effects of intramuscular stimulation with a heating-needle on spinal nociception, assessed by measuring nociceptive paw withdrawal reflex in rats. Additionally, involvement of the thalamic 'nociceptive discriminators' (thalamic mediodorsal (MD) and ventromedial (VM) nuclei), and opioid-mediated mechanisms were further explored. Descending facilitation and inhibition were elicited by 46°C noxious heating-needle stimulation, and were regulated by thalamic MD and VM nuclei, respectively. In contrast, innocuous heating-needle stimulation at a temperature of 43°C elicited descending inhibition modulated by the thalamic VM nucleus alone. Microinjection of µ/δ/κ-opioid receptor antagonists ß-funaltrexamine hydrochloride/naltrindole/nor-binaltorphimine, into the VM nucleus attenuated the 46°C intramuscular heating-needle stimulation-evoked descending inhibition, whereas treatment of the MD nucleus with ß-funaltrexamine hydrochloride significantly decreased the descending facilitation. By contrast, descending inhibition evoked by 43°C heating-needle stimulation was only depressed by naltrindole, as opposed to µ- and κ-opioid receptor antagonists, which failed to influence descending inhibition. The present study reveals distinct roles of µ-opioid receptors in the function of thalamic MD and VM nuclei,which exert facilitatory and inhibitory actions on nociception. Furthermore, innocuous, but not noxious, intramuscular heating-needle stimulation targeting δ-opioid receptors is suggested to be a promising avenue for the effective inhibition of pain.

Band gap engineering of FeS2 under biaxial strain: a first principles study.

The promising photovoltaic activity of pyrite (FeS2) is attributed to its excellent optical absorptivity and earth abundance, but its band gap, 0.95 eV, is slightly lower than the optimum value of 1.3 eV. Here we report the first investigation of strained FeS2, whose band gap can be increased by ∼0.3 eV. The influence of uniaxial and biaxial strains on the atomic structure as well as the electronic and optical properties of bulk FeS2 is systematically examined by the first principles calculations. We found that the biaxial strain can effectively increase the band gap with respect to uniaxial strain. Our results indicate that the band gap increases with increasing tensile strain to its maximum value at 6% strain, but under the increasing compressive strain, the band gap decreases almost linearly. Moreover, the low intensity states at the bottom of the conduction band disappear and a sharp increase in the intensity appears at the lower energy level under the tensile strain, which causes the red shift of the absorption edge and enhances the overall optical absorption. With the increase of the band gap and enhanced optical absorption, FeS2 will make a better photovoltaic material.

Self-assembled monolayers of CH3S from the adsorption of CH3SSCH3 on Au(111).

By performing density functional theory calculations, we have examined the adsorption of dimethyl disulfide (CH3SSCH3) on Au(111). In addition, we have also charted the reaction paths leading to dissociation of the S-S bond and the formation of thiolate-adatom species. Further, we have simulated the scanning tunneling microscopic (STM) images of the key adsorption intermediates and products and compared them with the experimental data available in the literature. In summary, our computations show that CH3SSCH3 adsorbs on Au(111) non-dissociatively with a moderate adsorption energy 0.42 eV for the trans-conformation which is 0.24 eV more stable than its cis-isomer. When the adsorbed trans-CH3SSCH3 dissociates at low temperature, the two CH3S fragments are retained by the closest neighboring sites and the trans-conformation of them prior to S-S dissociation can be preserved. The activation barrier to rotating the CH3S fragments on Au(111) is 0.17 eV so a moderate temperature rise can facilitate the transformation of the trans-conformation and generate a mixture of the trans- and cis-conformation. Our calculations also show that intrinsic defects such as gold adatoms (Auad) are active in CH3SSCH3 dissociation in two mechanisms: a direct mechanism in which CH3SSCH3 dissociation drives Auad formation and CH3S-Auad formation simultaneously, with leftover vacancies as by-products; a sequential mechanism in which Auad is present in advance and subsequently interacts with a nearby CH3S fragment to form CH3S-Auad. The respective activation barriers are 0.15 and 0.32 eV for the trans- and cis-CH3S-Auad-SCH3 complex along the direct mechanism, and 0.21 and 0.18 eV along the sequential mechanism.

Effects of intrinsic defects on methanthiol monolayers on Cu(111): a density functional theory study.

Density functional theory calculations were used to examine the effects of intrinsic surface defects of Cu(111) on the adsorption of methylthiol (CH3SH). The examination covers both the initial non-dissociative adsorption and the subsequent dissociation reaction pathways to form intermediate and final reaction products. By comparing the most probable adsorption structures likely formed after the adsorption of CH3SH on Cu(111) with and without the presence of adatoms (Cu(ad)) and vacancies, this computational work offers new insights about the geometry and thermodynamic stability of these structures. Particularly, it reveals a new type of surface complexes having two CH3S bonding to one Cu(ad) (referred therein as CH3S-Cu(ad)-CH3S). In addition, this work also yields new reaction dynamics results on transition states and activation barriers. The results reveal that the presence of Cu(ad) indeed significantly changes the kinetics of adsorption and dissociation of CH3SH on Cu(111). The most kinetically favorable reaction pathway turns out to be that involving the formation of a special surface complex formed by one Cu(ad) plus two CH3S fragments from the dissociation of CH3SH, with the two S atoms located at the bridge sites of Cu(111). Finally, this work also gives simulated scanning tunneling microscopic images for the most important adsorption species in the course of the transition from CH3SH∕Cu(111) to CH3S∕Cu(111), which may stimulate future experimental studies of self-assembled monolayers on practical metal substrates such as thiols on copper.

[Relationship between simulated weightlessness-induced muscle spindle change and muscle atrophy].

One of the most important and urgent issues in the field of space medicine is to reveal the potential mechanism underlying the disused muscle atrophy during the weightlessness or microgravity environment. It will conduce to find out effective methods for the prevention and treatment of muscle atrophy during a long-term space flight. Increasing data show that muscle spindle discharges are significantly altered following the hindlimb unloading, suggesting a vital role in the progress of muscle atrophy. In the last decades, we have made a series of studies on changes in the morphological structure and function of muscle spindle following simulated weightlessness. This review will discuss our main results and related researches for understanding of muscle spindle activities during microgravity environment, which may provide a theoretic basis for effective prevention and treatment of muscle atrophy induced by weightlessness.

[Method of isolation of intrafusal fibres of muscle spindle in soleus of rats].

Capsule restricts the further study on muscle spindle function and the involved mechanism. The aim of this study was to establish the isolation method of intrafusal fibres from the isolated rat muscle spindle. Intrafusal fibres were harvested from muscle spindle of soleus muscle in rats using neutrase-collagenase digestion. A variety of incubation mediums have been tested to find out an appropriate medium of intrafusal fibers in vitro. Trypan blue staining was used to detect cell death, and patch clamp was used to record resting potential. The results showed that the intrafusal fibres incubated with amine acid-saline solution were almost all dead. DMEM could maintain good condition of the fibres, but excess CO2 ventilation would induce cellular swelling or even death. While Leiboviz's 15 (L-15) medium can guarantee 1-2 h of physiological condition of the intrafusal fibres. Coverslips treated with gelatin, polylysine and serum was the better interfaces for the intrafusal fibres to adhere easily, compared with regularly treated coverslip. The resting potential of intrafusal fibres was (-45.3 ± 5.1) mV, consistent with others obtained from in vivo muscle spindle from cats and frogs. These results suggest that the isolation method of the intrafusal fibres has been successfully established in the present study, providing a new approach in better understanding of muscle spindle activities and the involved mechanism.

[Relationship between mRNA expression of MnSOD and manganese neurotoxicity].

OBJECTIVE: To investigate the relationship between mRNA expression of manganese superoxide dismutase (MnSOD) and manganese neurotoxicity. METHODS: Thirty-one patients with occupational chronic manganese poisoning (case group), as well as 31 controls exposed to the same condition (control group), were included in the study. Whole blood RNA was extracted, and the mRNA expression of MnSOD was measured by RT-PCR; the two groups were compared in terms of the mRNA expression of MnSOD. PC12 cells were treated with 0, 100, 200, 400, 600, 800, and 1000 ümol/L MnCl2 for l, 2, 3, and 4 d; the cell viability was determined by MTT assay, and the mRNA expression of MnSOD was measured by RT-PCR. RESULTS: The case group had significantly lower mRNA expression of MnSOD than the control group (0.390 ± 0.080 vs 0.582 ± 0.219, P < 0.05). MnCl2 had a toxic effect on PC12 cells; the concentration of MnCl2 was positively correlated with the toxic effect but negatively correlated with the mRNA expression of MnSOD. CONCLUSION: MnSOD mRNA may be involved in the manganese-induced damage of nerve cells. It is hypothesized that high mRNA expression of MnSOD may play an inhibitory effect on manganese neurotoxicity.

Variation in microbiological heterogeneity in Chinese strong-flavor Baijiu fermentation for four representative varieties of sorghum.

The quality and composition of strong-flavor Baijiu (SFB), a type of Chinese liquor, depends on the variety of sorghum used in fermentation. However, comprehensive in situ studies measuring the effects sorghum varieties on the fermentation are lacking and the underlying microbial mechanisms remains poorly understood. We studied the in situ fermentation of SFB by using metagenomic, metaproteomic, and metabolomic techniques across four sorghum varieties. Sensory characteristics were best for SFB made from glutinous variety Luzhouhong, followed by glutinous hybrid Jinnuoliang and Jinuoliang, and those made with non-glutinous Dongzajiao. In agreement with sensory evaluations, the volatile composition of SFB samples differed between sorghum varieties (P < 0.05). Fermentation of different sorghum varieties varied in microbial diversity, structure, volatile compounds, and physicochemical properties (pH, temperature, starch, reducing sugar, and moisture) (P < 0.05), with most changes occurring within the first 21 days. Additionally, the microbial interactions and their relationship with volatiles, as well as the physicochemical factors that govern microbial succession, differed between varieties of sorghum. The number of physicochemical factors affecting bacterial communities outweighed those affecting fungal communities, suggesting that bacteria were less resilient to the brewing conditions. This correlates with the finding that bacteria play a major role in the differences in microbial communities and metabolic functions during fermentation with the different varieties of sorghum. Metagenomic function analysis revealed differences in amino acid and carbohydrate metabolism between sorghum varieties throughout most of the brewing process. Metaproteomics further indicated most differential proteins were found in these two pathways, related to differences in volatiles between sorghum varieties of Baijiu and originating from Lactobacillus. These results provide insight into the microbial principles underlying Baijiu production and can be used to improve the quality of Baijiu by selecting the appropriate raw materials and optimizing fermentation parameters.

Prolonged hindlimb unloading leads to changes in electrophysiological properties of L5 dorsal root ganglion neurons in rats after 14 days.

INTRODUCTION: The purpose of this study was to evaluate the electrophysiological changes observed in dorsal root ganglion (DRG) neurons in a simulated weightlessness rat model and to assess the mechanisms involved in these changes. METHODS: The simulated weightlessness model was created by hindlimb unloading (HU). Whole-cell patch-clamp recordings, conduction velocity measurement, and ultrastructural observation were performed. RESULTS: In the HU rats, the action potentials had a longer duration and slower falling rate, but there was no significant effect on amplitude or rate of rise. HU also induced lowering of rheobase and of the threshold potential, making the cells more excitable. The conduction velocities in the proximal branches of ganglion cells were also decreased, and some degenerative changes in the myelin sheath were noted. CONCLUSIONS: This study provides evidence of plasticity of DRG neurons induced by HU. The changes observed might contribute to impaired motor performance in rats submitted to HU.

Antimicrobial and immunomodulatory activity of beta-defensin from the Chinese spiny frog (Quasipaa spinosa).

The ß-defensins are important components of the vertebrate innate immune system. While mammalian ß-defensins have wide-ranging antibacterial and immunomodulatory activities, those of amphibians remain largely uncharacterised. In this study, ß-defensin cDNA was identified from the skin transcriptome of the Chinese spiny frog Quasipaa spinosa. This ß-defensin (QS-BD) consists of a signal and a mature peptide. Sequence alignments with other amphibian ß-defensins showed conservation of the functional mature peptide and that its closest relative is ß-defensin from Zhangixalus puerensis. Synthetic QS-BD showed antibacterial activity against Vibrio vulnificus, Vibrio harveyi, Streptococcus iniae, and Aeromonas hydrophila. QS-BD showed bactericidal activity by destroying the cell membrane integrity, but did not hydrolyse genomic DNA. QS-BD treatment promoted respiratory bursts and upregulated the expression of interleukin-1ß and tumour necrosis factor-α in the murine leukemic monocyte/macrophage cell line RAW264.7. This is the first demonstration of immunomodulatory activity by an amphibian ß-defensin.

Brevinin-2PN, an antimicrobial peptide identified from dark-spotted frog (Pelophylax nigromaculatus), exhibits wound-healing activity.

Brevinins exhibit a wide range of structural features and strong biological activities. Brevinin-2, derived from several amphibians, has shown antimicrobial activities. However, little is known about the wound-healing activity of brevinin-2. In this study, brevinin-2 cDNA was identified from the skin transcriptome of the dark-spotted frog (Pelophylax nigromaculatus) and it comprises a signal peptide, a propeptide, and a mature peptide. Sequence alignment with brevinin-2 derived from other amphibians showed variability of the mature peptide, and the presence of a C-terminal cyclic heptapeptide domain (Cys-Lys-Xaa4-Cys) in the mature peptide. Dark-spotted frog brevinin-2 belonged to the brevinin-2 cluster and was closely related to brevinin-2HB1 from Pelophylax hubeiensis. Synthetic dark-spotted frog brevinin-2 mature peptide (brevinin-2PN) exhibited antibacterial activity against several pathogens by destroying cell membrane integrity and hydrolysis of genomic DNA. Brevinin-2PN exhibited significant wound-healing activity by accelerating the healing of human skin fibroblast cell scratches, influencing cell migration, and stimulating gene expression of growth factors.

[Decreased neurotrophin-3 expression of intrafusal muscle fibers in rat soleus muscles under simulated weightlessness].

The present study aimed to study the changes of neurotrophin-3 (NT-3) expression of intrafusal muscle fibers in rat soleus muscles under simulated weightlessness. The tail-suspension (SUS) rat model was used to simulate weightlessness. Forty mature female Sprague-Dawley rats were randomly assigned to ambulatory control (CON), 3-day SUS, 7-day SUS, 14-day SUS and 21-day SUS groups. Immunohistochemistry ABC staining method and enzyme linked immunosorbent assay (ELISA) were used to detect the NT-3 expression of intrafusal muscle fibers in rat soleus muscles. The results from the immunohistochemistry staining technique showed that the extrafusal muscle fibers did not exhibit the NT-3-like immunoreactivity, and NT-3-like immunoreactivity was mainly expressed in nuclear bag 1 and nuclear bag 2 fibers of the muscle spindles. The ELISA results showed that the expression quantity of NT-3 in rat soleus muscles in control, 3-day SUS, 7-day SUS, 14-day SUS and 21-day SUS groups were (14.23±1.65), (14.11±1.53), (13.09±1.47), (12.45±1.51) and (9.85±1.52) pg/mg of tissue respectively. Compared to the control group, the expression quantity of NT-3 was significantly decreased after 14 days of SUS (P<0.05). After 21 days of SUS, the NT-3 expression was further reduced (P<0.01). These results suggest that simulated weightlessness induces an obvious decrease in the NT-3 expression level of intrafusal fibers in rat soleus muscles. Accompanying the simulated weightlessness extension, NT-3 expression in rat soleus muscle spindles is progressively decreased. These changes may contribute to the proprioceptive adaptations to microgravity.

[Electrophysiological characteristics of the isolated muscle spindle in rats].

The aim of this study was to observe the electrophysiological characteristics of the isolated rat muscle spindle. The muscle spindle was isolated from rat soleus and the afferent discharge of the isolated muscle spindle was recorded by air-gap technique. In the basic physiological salt solution, the spontaneous impulses of muscle spindle were at a lower level with irregular intervals. The mean frequency of afferents was (51.78 ± 25.63) impulses/1 000 s (n = 13). The muscle spindle afferents were significantly increased and maintained over time by the addition of certain amino acids during the observation. The number of the action potential recorded per 1 000 s was 200-1 000 [mean: (687.62 ± 312.56) impulses/1 000 s, n = 17]. In addition to the typical propagated action potential, a large number of abortive spikes were observed. The results indicate that the activities of isolated muscle spindles in rats can be well maintained by the addition of certain amino acids. The results initially establish and provide the possibility for further research conducted in isolated rat muscle spindles.