Yun Zhu

Publications (8)17.82 Total impact

• Article: Joint Associations of 61 Genetic Variants in the Nicotinic Acetylcholine Receptor Genes with Subclinical Atherosclerosis in American Indians: A Gene-Family Analysis.

  Jingyun Yang, Yun Zhu, Elisa T Lee, Ying Zhang, Shelley A Cole, Karin Haack, Lyle G Best, Richard B Devereux, Mary J Roman, Barbara V Howard, Jinying Zhao
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  ABSTRACT: BACKGROUND: -Atherosclerosis is the underlying cause of cardiovascular disease, the leading cause of morbidity and mortality in all American populations including American Indians. Genetic factors play an important role in the etiology of atherosclerosis. While a single SNP may explain only a small portion of variability in disease, the joint effect of multiple variants in a pathway on disease susceptibility could be large. METHODS AND RESULTS: -Using a gene-family analysis, we investigated the joint associations of 61 tag SNPs in seven nicotinic acetylcholine receptors (nAChRs) genes with subclinical atherosclerosis, as measured by carotid intima-media thickness (IMT) and plaque score, in 3,665 American Indians from 94 families recruited by the Strong Heart Family Study (SHFS). Although multiple SNPs showed marginal association with IMT and/or plaque score individually, only a few survived adjustments for multiple testing. However, simultaneously modeling of the joint effect of all 61 SNPs in seven nAChRs genes revealed significant association of the nAChR gene family with both IMT and plaque score, independent of known coronary risk factors. CONCLUSIONS: -Genetic variants in the nicotinic acetylcholine receptors gene family jointly contribute to subclinical atherosclerosis in American Indians participated in the SHFS. These variants may influence the susceptibility of atherosclerosis through pathways other than cigarette smoking per se.
  Circulation Cardiovascular Genetics 12/2012; · 6.11 Impact Factor
• Article: A gene-family analysis of 61 genetic variants in the nicotinic acetylcholine receptor genes for insulin resistance and type 2 diabetes in American Indians.

  Jingyun Yang, Yun Zhu, Shelley A Cole, Karin Haack, Ying Zhang, Laura A Beebe, Barbara V Howard, Lyle G Best, Richard B Devereux, Jeffrey A Henderson, Patricia Henderson, Elisa T Lee, Jinying Zhao
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  ABSTRACT: Cigarette smoking is a risk factor for type 2 diabetes. Genetic variants in the nicotinic acetylcholine receptor (nAChR) genes have been associated with smoking phenotypes and are likely to influence diabetes. Although each single variant may have only a minor effect, the joint contribution of multiple single nucleotide polymorphisms (SNPs) to the occurrence of disease may be larger. In this study, we conducted a gene-family analysis to investigate the joint impact of 61 tag SNPs in 7 nAChRs genes on insulin resistance and type 2 diabetes in 3,665 American Indians recruited by the Strong Heart Family Study. Results show that although multiple SNPs showed marginal individual association with insulin resistance and type 2 diabetes, only a few can pass adjustment for multiple testing. However, a gene-family analysis considering the joint impact of all 61 SNPs reveals significant association of the nAChR gene family with both insulin resistance and type 2 diabetes (both P < 0.0001), suggesting that genetic variants in the nAChR genes jointly contribute to insulin resistance and type 2 diabetes among American Indians. The effects of these genetic variants on insulin resistance and diabetes are independent of cigarette smoking per se.
  Diabetes 05/2012; 61(7):1888-94. · 8.29 Impact Factor
• Article: Estrogenic activity of bio-degradation products of C-heavy oil revealed by gene-expression profiling using an oligo-DNA microarray system.

  Yun Zhu, Keiko Kitamura, Akihiko Maruyama, Takanori Higashihara, Ryoiti Kiyama
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  ABSTRACT: Degradation of heavy oil by bacteria to decompose organic compounds such as aliphatic and aromatic hydrocarbons has been used in bioremediation. However, the biological and environmental effects of the degradation products including intermediates are still not clear. Here, we monitored the degradation of C-heavy oil by analyzing the products formed in cultures with oil-degrading bacteria (complex microbes or a single bacterial strain). Furthermore, proliferation assays using breast cancer MCF-7 cells and gene-expression profiling of MCF-7 cells using oligonucleotide-DNA microarrays were performed to evaluate the estrogenic activity of the degradation products. While the products did not show any significant cell-proliferative activity, the oil samples cultured for longer periods (2-3 months), whether cultured with mixed microbes or a single bacterial strain, showed gene-expression profiles similar to that of 17β-estradiol (E2). These results suggest that oil-degradation products have estrogenic activity, and estrogen-like components could possibly be produced during the degradation process.
  Environmental pollution (Barking, Essex: 1987) 05/2012; 168:10-4. · 3.43 Impact Factor
• Article: Spontaneous firing properties of rat medial vestibular nucleus neurons in brain slices by infrared visual patch clamp technique

  Jiao Xia, Weijia Kong, Yun Zhu, Yan Zhou, Yu Zhang, Changkai Guo
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  ABSTRACT: Domestic application of infrared patch clamp techniques on brain slices is limited. The key of the technique is to prepare high-quality brain slices. The present paper describes the preparation procedure of brainstem slices and the spontaneous firing properties of rat medial vestibular nucleus (MVN) neurons. By infrared differential interference contrast technique, neurons of rat MVN were visualized directly at the depth of 50–100 μm underneath the surface of slices. Firing activities of MVN neurons were recorded by the whole-cell patch clamp technique in artificial cerebrospinal fluid (ACSF) and low Ca2+-high Mg2+ fluid. The firing mode was more irregular and depressive in low Ca2+-high Mg2+ fluid than in ACSF. According to the averaged waveform of action potentials, cells were classified as the neurons with monophasic after-hyperpolarization potential (AHP), and the neurons with biphasic AHP. The resting membrane potential (RMP), input resistance (Rin) and membrane capacitance (Cm) of neurons were recorded and compared between groups. With infrared videomicroscopy, patch clamp recordings could be made under direct observation in freshly prepared brainstem slices. The discharge activities of MVN neurons were spontaneous and the firing mode was modulated by extracellular calcium concentration. The basic membrane properties of two types of neurons were not significantly different, while the differences in waveform might play a role in the segregation between tonic and kinetic cells.
  Frontiers of Medicine in China 04/2012; 2(3):264-268.
• Article: [Comparative morphology of the two type's hair cells from saccule and utricle under inverted phase contrast microscope].

  Xixun Kang, Weijia Kong, Song Zhang, Changkai Guo, Yanjun Wang, Yun Zhu, Jiao Xia
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  ABSTRACT: To explore more reliable standards for identifying vestibular hair cells of saccule and utricle prepared in studies with patch clamp technique under inverted phase contrast microscope. The length and width of two type's hair cell's were measured besides the length of cilia, and all datas were analyzed statistically. The width and length of cilia of two types hair cells in saccule and utricle from guinea pig were similar. The length of type I was longer than that of type II, so the ratio between length and width was larger and the ratio of the length between cilia and cell body was small. Two type's hair cells of saccule and utricle from guinea pig may be distinguished through the ratio of cell body's length and width even the ratio of the length between cilia and cell body, besides the standards before.
  Lin chuang er bi yan hou ke za zhi = Journal of clinical otorhinolaryngology 12/2009; 23(23):1082-5.
• Article: [Intrinsic membrane properties of rat medial vestibular nucleus neurons and their responses to simulated vestibular input signals].

  Jiao Xia, Wei-jia Kong, Yun Zhu, Yan Zhou, Yu Zhang, Chang-kai Guo
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  ABSTRACT: To study the membrane properties of rat medial vestibular nucleus (MVN) neurons and their firing responses to simulated input signals of peripheral vestibular system, and to discuss how the intrinsic membrane properties contribute to physiologic functions in central vestibular system. By using infrared differential interference contrast technique, whole-cell recordings were made from rat MVN neurons under direct observation. On the basis of their averaged action potential shapes, the MVN neurons were classified. Linear and non-linear currents were put into the neurons to simulate the input signals of peripheral vestibular system. The differences of intrinsic membrane properties and firing response dynamics were observed between two types. The discharge activities were recorded in MVN neurons, which remained in low Ca2+-high Mg2+ artificial cerebrospinal fluid (ACSF). Neurons are classified as type A (33%) characterized by a single deep after-hyperpolarization (AHP) and A-like rectification, or type B (63%) characterized by double AHP, and another two neurons with all or none of the characters. The passive membrane properties were not significantly different between type A and type B neurons, while part of active membrane properties was significantly different. Both type A and B neurons well responded to simulated current inputs, but disparities existed in response range and firing dynamics. The discharge activities of MVN neurons were initiated by their intrinsic membrane properties. Most MVN neurons were classified as type A and B, while several showed unrepresentative firing properties. Linear and nonlinear inputs evoked a heterogeneous range of firing responses. The differences of response range and firing dynamics between neurons may determine their different physiological functions.
  Zhonghua er bi yan hou tou jing wai ke za zhi = Chinese journal of otorhinolaryngology head and neck surgery 11/2008; 43(10):767-72.
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  Article: [Properties of cholinergic receptor-mediated ion channels on type I vestibular hair cells of guinea pigs].

  Yun Zhu, Wei-Jia Kong, Jiao Xia, Yu Zhang, Hua-Mao Cheng, Chang-Kai Guo
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  ABSTRACT: To confirm the existence of cholinergic receptors on type I vestibular hair cells (VHCs I) of guinea pigs and to study the properties of the cholinergic receptor-mediated ion channels on VHCs I, electrophysiological responses of isolated VHCs I to external ACh were examined by means of whole-cell patch-clamp recordings. The results showed that 7.5% (21/279) VHCs I were found to be sensitive to ACh (10-1000 μmol/L). ACh generated an outward current in a steady, slow, dose-dependent [EC(50) was (63.78±2.31) μmol/L] and voltage-independent manner. In standard extracellular solution, ACh at the concentration of 100 μmol/L triggered a calcium-dependent current of (170±15) pA at holding potential of -50 mV, and the current amplitude could be depressed by extracellularly added calcium-dependent potassium channel antagonist TEA. The time interval for the next complete activation of ACh-sensitive current was no less than 1 min. The ion channels did not shut off even when they were exposed to ACh for an extended period of time (8 min). The results suggest that dose-dependent, calcium-dependent and voltage-independent cholinergic receptors were located on a few of the VHCs I investibular epithelium of guinea pigs. The cholinergic receptors did not show desensitization to ACh. This work reveals the existence of efferent neurotransmitter receptors on VHCs I and helps in understanding the function of vestibular efferent nervous system, and may provide some useful information on guiding the clinical rehabilitative treatment of vertigo.
  Sheng li xue bao: [Acta physiologica Sinica] 07/2008; 60(3):375-81.
• Article: [Electrophysiological characteristics of muscarinic cholinergic receptor in rat medial vestibular nucleus neurons by visual patch clamp technique].

  Yu Zhang, Wei-jia Kong, Bang-hua Liu, Chang-kai Guo, Da-wei Sun, Jiao Xia, Yun Zhu, Jian Zhang
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  ABSTRACT: To establish the visual patch clamp whole-cell recording technique and study the properties and functional significance of muscarinic receptor-mediated currents in rat medial vestibular nucleus neurons (MVNn). Brain slices containing the MVN were prepared from fifteen Wistar rats. By combining infrared differential interference contrast (IR-DIC) technique and CCD-Camera system with visual patch clamp whole-cell recording technique, twenty healthy neurons were located and muscarinic receptor-mediated currents in rat MVNn were observed and analyzed. Visual patch clamp technique can be used to make direct localization and to make sure of active neuron. In MVNn, a comparison of the current-voltage relationships before and during the application of muscarine, which revealed an increase in the slope of the I-V curve and the reversal potential for this response lay at (-88.4 +/- 4.9) mV (x +/- s), indicates that the activation of muscarinic cholinergic receptors leads to a decrease in potassium current. The test in the voltage sensitivity of the muscarine-induced response, which showed that the effect had a linear current-voltage relationship and reversed at (-86.7 +/- 3.5) mV, indicates that the potassium current blocked by muscarine corresponds to the voltage-insensitive leak potassium current. Visual patch clamp technique, which was considered better than blind patch clamp technique, can improve the success of sealing process. By the analysis of muscarinic receptor-mediated currents, the data provide support that muscarinic cholinergic mechanisms play a prominent role in the modulation of the excitability of MVNn and also offer a new idea for the efficacy of anticholinergic drugs.
  Zhonghua er bi yan hou tou jing wai ke za zhi = Chinese journal of otorhinolaryngology head and neck surgery 02/2007; 42(1):48-52.