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Biomedical subjects

Ming Tang

Publications and source records attributed to Ming Tang.

At least 19 recordsLinked to original sources

A Study on Differential Proteomics in Differentiated Gastric Adenocarcinoma With Low-grade Atypia Based on Paraffin-embedded Tissues.

In this study, we analyzed and characterized differentially expressed proteins in differentiated gastric adenocarcinoma with low-grade atypia for screening potential protein markers. We collected gastric tissue specimens from 90 patients treated at the Pathology Department of the First People's Hospital of Yunnan Province, China, between January 2019 and December 2022. These specimens had been fixed in 10% neutral-buffered formalin and embedded in paraffin. We classified these samples into 3 groups: the control group (normal gastric mucosa), the low-grade atypia group (differentiated gastric adenocarcinoma with low-grade atypia), and the high-grade atypia group (differentiated gastric adenocarcinoma with high-grade atypia), consisting of 30 cases in each group. We analyzed differential proteomes with the data-independent acquisition-mass spectrometry (DIA-MS) methodology and selected 4 differentially expressed proteins that were subjected to immunohistochemistry (IHC) staining for validation. A total of 4406 proteins were identified, among which 598 and 357 proteins were statistically different in the low-grade atypia group as compared with the control group and the high-grade atypia group, respectively. IHC staining showed that the expression of FHL3, CSRP2, and FCGR3A was significantly higher in the low-grade atypia group than in the control group ( P <0.05) and significantly higher in the high-grade atypia group than in the low-grade atypia group ( P <0.05). FHL2 expression was negative to weakly positive in the control and low-grade atypia groups and not significantly different between the 2 groups, whereas FHL2 expression in the high-grade atypia group was significantly higher than in the control and low-grade atypia groups ( P <0.05). Proteomic analysis is helpful for discovering new protein markers. Using a combination of FHL3, CSRP2, and FCGR3A can increase the accuracy of the pathologic diagnosis of differentiated gastric adenocarcinoma with low-grade atypia.

Humans↗

WDFY2 promotes MRN complex formation required for homologous recombination-mediated DNA repair.

The MRE11-RAD50-NBS1 (MRN) complex is fundamental for detecting and repairing DNA double-strand breaks (DSBs), thereby safeguarding genome integrity. However, the precise mechanism governing MRN complex recruitment to DSBs remains largely unexplored. Here, we identify WD40- and FYVE domain-containing protein 2 (WDFY2) as an important regulator of MRN complex formation at DNA damage sites, facilitating homologous recombination (HR) repair. Mechanistically, WDFY2 is phosphorylated at serine 84 by the ATM-CHK2 axis, priming it for recruitment to DSBs. Through direct interactions with MRE11 and NBS1, WDFY2 bridges the MRE11-RAD50 subcomplex with NBS1, thereby promoting MRN complex formation at DSBs and DNA end resection. WDFY2 deficiency, as well as the non-phosphorylatable S84A mutant, results in impaired HR repair and reduced cell survival following DNA damage. Collectively, our findings establish WDFY2 as a key platform for MRN complex loading at DSBs and HR repair, highlighting it as a potential therapeutic target for cancer treatment.

Humans↗

Motilin activates neurons in the rat amygdala and increases gastric motility.

Motilin and motilin receptors have been found in most regions of the brain, including the amygdala, one of the most important parts of the limbic system. Our previous study found that administration of motilin in the hippocampus stimulates gastric motility. We now explore the effect of motilin in the amygdala on gastric motility. In conscious rats, gastric motility was recorded after microinjection of motilin, motilin receptor antagonist (GM-109) or a mixture of the two into the basomedial amygdala nucleus (BMA). In anesthetized rats the changes of spontaneous discharges of gastric distention sensitive neurons (GDSN) in the BMA were recorded after intracerebroventricular (i.c.v.) microinjection of motilin or GM-109. In conscious rats the amplitude of gastric contractions increased dose-dependently after microinjection of motilin in the BMA, and decreased after microinjection of GM-109. The excitatory or inhibitory effects induced by motilin or GM-109 alone, were weakened by microinjection of a mixture solution of both. The spontaneous discharge frequency of gastric distention excitatory neuron (GDEN) was mainly inhibited by i.c.v. microinjection of motilin but excited by GM-109. In contrast, the spontaneous discharge frequency of gastric distention inhibitory neuron (GDIN) was mainly excited by motilin, but inhibited by GM-109. Our findings suggest that motilin may regulate gastric motility by modulating neural pathways in the BMA.

Amygdala↗

Trehalose-protected lipid membranes for determining membrane protein structure and insertion.

Trehalose preserves lipid bilayers during dehydration and rehydration by replacing water to form hydrogen bonds between its own OH groups and lipid headgroups. We compare the lipid conformation and dynamics between trehalose-protected lyophilized membranes and hydrated membranes, to assess the suitability of the trehalose-containing membrane as a matrix for membrane protein structure determination. (31)P spectra indicate that the lipid headgroup of trehalose-protected dry POPC membrane (TRE-POPC) have an effective phase transition temperature that is approximately 50K higher than that of the hydrated POPC membrane. In contrast, the acyl chains have similar transition temperatures in the two membranes. Intramolecular lipid (13)C'-(31)P distances are the same in TRE-POPC and crystalline POPC, indicating that the lipid headgroup and glycerol backbone conformation is unaffected by trehalose incorporation. Intermolecular (13)C-(31)P distances between a membrane peptide and the lipid headgroups are 10% longer in the hydrated membrane at 226 K than in the trehalose-protected dry membrane at 253 K. This is attributed to residual motions in the hydrated membrane, manifested by the reduced (31)P chemical shift anisotropy, even at the low temperature of 226 K. Thus, trehalose lyoprotection facilitates the study of membrane protein structure by allowing experiments to be conducted at higher temperatures than possible with the hydrated membranes.

1,2-Dipalmitoylphosphatidylcholine↗

Membrane-dependent oligomeric structure and pore formation of a beta-hairpin antimicrobial peptide in lipid bilayers from solid-state NMR.

We used solid-state NMR spectroscopy to investigate the oligomeric structure and insertion of protegrin-1 (PG-1), a beta-hairpin antimicrobial peptide, in lipid bilayers that mimic either the bacterial inner membrane [palmitoyloleoylphosphatidyl ethanolamine and palmitoyloleoylphosphatidylglycerol (POPE/POPG) bilayers] or the red blood cell membrane [neutral palmitoyloleoylphosphatidylcholine (POPC)/cholesterol bilayers]. (1)H spin diffusion from lipids to the peptide indicates that PG-1 contacts both the lipid acyl chains and the headgroups in the anionic membrane but resides far from the lipid chains in the POPC/cholesterol bilayer. (19)F spin diffusion data indicates that 75% of the beta-hairpins have homodimerized N strands and C strands in the anionic membrane. The resulting (NCCN)(n) multimer suggests a membrane-inserted beta-barrel enclosing a water pore. The lipids surrounding the beta-barrel have high orientational disorder and chain upturns, thus they may act as fillers for the pore. These results revise several features of the toroidal pore model, first proposed for magainin and subsequently applied to PG-1. In the POPC/cholesterol membrane, the N and C strands of PG-1 cluster into tetramers, suggesting the formation of beta-sheets on the membrane surface. Thus, the membrane composition plays a decisive role in defining the assembly and insertion of PG-1. The different oligomeric structures of PG-1 help to explain its greater toxicity for bacteria than for eukaryotic cells.

Anions↗

Immunoglobulin alpha heavy chain derived from human epithelial cancer cells promotes the access of S phase and growth of cancer cells.

It is generally believed that under normal conditions only B lymphocytes express immunoglobulin. Interestingly, our previous work demonstrated that epithelial cancer tissues and cancer cell lines also express Ig alpha heavy chain. So we further analyzed the potential function of cancer-derived Ig alpha heavy chain. Here we show that blockade of cancer-derived Ig alpha suppressed the growth and viability of cancer cells. And cancer-derived Ig alpha promotes the malignant proliferation ability of cancer cells. Furthermore, we demonstrated that Ig alpha protein increases the access percentage of S phase from the early mitosis of synchronized cancer cells. Our findings support the important role of cancer-derived Ig alpha as a growth promoter of cancer cells, and reveal a novel molecular mechanism for growth and proliferation of cancer cells.

Antibodies, Blocking↗

Condensation in a zero range process on weighted scale-free networks.

We study the condensation phenomenon in a zero range process on weighted scale-free networks in order to show how the weighted transport influences the particle condensation. Instead of the approach of grand canonical ensemble which is generally used in a zero range process, we introduce an alternate approach of the mean-field equations to study the dynamics of particle transport. We find that the condensation on the scale-free network is easier to occur in the case of weighted transport than in the case of weight-free networks. In the weighted transport, especially, a dynamical condensation is even possible for the case of no interaction among particles, which is impossible in the case of weight-free networks.

Journal Article↗

Molecular and cytogenetic characterization of an Oryza officinalis-O. sativa chromosome 4 addition line and its progenies.

The wild species Oryza officinalis Wall. ex Watt (2n = 24, CC) is a valuable genetic resource for rice (O. sativa L., 2n = 24, AA) breeding and genomics research. Genomic in situ hybridization (GISH) and molecular approaches were used to determine the nature and composition of the additional chromosome in a monosomic alien addition line (MAAL) of O. officinalis and its backcross progenies. The extra wild species chromosome in the MAAL (2n = 2x = 25) was a mosaic one, comprising of the long arm of chromosome 4 from O. officinalis and the short arm from O. sativa. Comparative analysis showed that O. sativa and O. officinalis shared high synteny of restriction fragment length polymorphism (RFLP) markers and low synteny of simple sequence repeat (SSR) markers. A DNA methylation alteration was revealed at C619 in the MAAL and progenies. Analysis of progenies of the MAAL indicated that introgression segments were small in size and introgression was not evenly distributed along the long arm. One recombination hot spot between C513 and RG177 was identified, which is in a gene-rich region.

Blotting, Southern↗

Grain boundary transitions in binary alloys.

A thermodynamic diffuse interface analysis predicts that grain boundary transitions in solute absorption are coupled to localized structural order-disorder transitions. An example calculation of a planar grain boundary using a symmetric binary alloy shows that first-order boundary transitions can be predicted as a function of the crystallographic grain boundary misorientation and empirical gradient coefficients. The predictions are compared to published experimental observations.

Journal Article↗

Action of beta-amyloid peptide₁₋₄₀ on I(HVA) and its modulation by ginkgolide B.

Whole-cell patch clamp recording was used to investigate the action of beta-amyloid peptide(1-40) (Abeta(1-40)) on high voltage-activated calcium channel current (I(HVA)) in acutely isolated hippocampal CA1 pyramidal neurons in rats and observe its modulation by ginkgolide B (GB). Drug was applied by extracellular bath or adding in the pipette solution, and its effect was determined by comparing the amplitude of I(HVA) before and after the drug application. Bath application of aggregated Abeta(1-40) at concentrations of 0.01~30 mumol/L increased the amplitude of I(HVA) in a dose-dependent manner by (5.43+/-3.01)% (n=8, P>0.05), (10.49+/-4.13) % (n=11, P>0.05), (40.69+/-8.01) % (n=16, P<0.01), (58.32+/-4.85) % (n=12, P<0.01), and (75.45+/-5.81) % (n=6, P<0.01), respectively, but had no effect on the I-V curve of I(HVA); fresh Abeta(1-40) almost had no effect on I(HVA) (n=5, P>0.05). L-type calcium channel antagonist nifedipine abolished the increase of I(HVA)by Abeta(1-40). The increase of I(HVA) by Abeta(1-40) (1.0 mumol/L) was enhanced to (66.19+/-5.74) % (P<0.05) by 8-Br-cAMP (membrane permeable analogue of cAMP) and to (73.21+/-6.90) % (P<0.05) by forskolin, an adenylyl cyclase (AC) agonist, and reduced to (20.08+/-2.18) % (P<0.05) by H-89, cyclic adenosine monophosphate (cAMP)-dependent protein kinase A (PKA) antagonist. GB effectively inhibited the increase of I(HVA) by Abeta(1-40). The results indicate that Abeta(1-40) leads to an intracellular calcium overload by increasing I(HVA) via AC-cAMP-PKA. This may be one of the mechanisms for its neurotoxicity. GB can prevent neurons from neurotoxicity by inhibiting abnormal calcium influx caused by Abeta(1-40).

Amyloid beta-Peptides↗

[Investigation on spontaneous electrical activity of murine embryonic heart using microelectrode arrays].

In our studies, we have applied a novel tool, microelectrode arrays (MEA), to investigate the electrophysiological properties of murine embryonic hearts in vitro. The electrical signals were recorded from the areas of the heart adhering to the 60 MEA electrodes, being called field potentials (FPs). As an extracelluar recording, the waveform of the FP appeared similar to a reversed action potential obtained from single cell by whole cell current clamp and the FP duration was comparable with the action potential duration. To study propagation of spontaneous electrical activity, we have compared the occurrence time of FPs recorded from different electrodes. It is shown that there was already an apparent A-V delay [(50.21+/-9.7) ms] at day 9.5 post coitum (E9.5) when heart was still tubular-like and atrium and ventricle were not separated anatomically, while occurence of FP at different electrodes of ventricular area were almost synchronous. Further, we looked into the modulation of spontaneous electrical activity during cardiac development: at E9.5 of embryonic development, 1 mumol/L of isoproterenol (Iso) increased beating frequency by (34.04+/-7.31)%, shortened the A-V delay by (20.00+/-6.44) % and prolonged FP duration. In contrast, 1 mumol/L of carbachol (CCh) slowed down beating frequency by (42.32+/-5.36) %, A-V conduction by (26.00+/-4.81) % and shortened FP duration; however at late stage (E16.5), the regulatory effect of Iso and CCh was strengthened. Therefore we conclude that cardiac conduction system is already established at E9.5 when the four-chambered heart is not formed yet and the regulation of spontaneous activity by sympathetic and para-sympathetic system is gradually matured during cardiac development.

Action Potentials↗

Orientation of a beta-hairpin antimicrobial peptide in lipid bilayers from two-dimensional dipolar chemical-shift correlation NMR.

The orientation of a beta-sheet membrane peptide in lipid bilayers is determined, for the first time, using two-dimensional (2D) (15)N solid-state NMR. Retrocyclin-2 is a disulfide-stabilized cyclic beta-hairpin peptide with antibacterial and antiviral activities. We used 2D separated local field spectroscopy correlating (15)N-(1)H dipolar coupling with (15)N chemical shift to determine the orientation of multiply (15)N-labeled retrocyclin-2 in uniaxially aligned phosphocholine bilayers. Calculated 2D spectra exhibit characteristic resonance patterns that are sensitive to both the tilt of the beta-strand axis and the rotation of the beta-sheet plane from the bilayer normal and that yield resonance assignment without the need for singly labeled samples. Retrocyclin-2 adopts a transmembrane orientation in dilauroylphosphatidylcholine bilayers, with the strand axis tilted at 20 degrees +/- 10 degrees from the bilayer normal, but changes to a more in-plane orientation in thicker 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidyl-choline (POPC) bilayers with a tilt angle of 65 degrees +/- 15 degrees . These indicate that hydrophobic mismatch regulates the peptide orientation. The 2D spectra are sensitive not only to the peptide orientation but also to its backbone (phi, psi) angles. Neither a bent hairpin conformation, which is populated in solution, nor an ideal beta-hairpin with uniform (phi, psi) angles and coplanar strands, agrees with the experimental spectrum. Thus, membrane binding orders the retrocyclin conformation by reducing the beta-sheet curvature but does not make it ideal. (31)P NMR spectra of lipid bilayers with different compositions indicate that retrocyclin-2 selectively disrupts the orientational order of anionic membranes while leaving zwitteronic membranes intact. These structural results provide insights into the mechanism of action of this beta-hairpin antimicrobial peptide.

Antimicrobial Cationic Peptides↗

Effect of hypoxia on hyperpolarization-activated current in mouse dorsal root ganglion neurons.

The properties of hyperpolarization-activated current (I(h)) in mouse dorsal root ganglion (DRG) neurons and the effect of hypoxia on the current have been studied using whole-cell configuration of the patch clamp technique. Under voltage-clamp mode, I(h), blocked by 1 mM extracellular CsCl, was present in 75.5% of mouse DRG neurons. The distribution rate increased as the neurons become larger, 5.3%, 79.8% and 94.2% in small, medium and large neurons, respectively. Both I(h) density and the rate of I(h) activation increased in response to more hyperpolarized potential. The activation of I(h) current in larger neuron was faster than in smaller neuron, there was a significant correlation between the time constant of I(h) activation and neuron's size. However, I(h) density did not show any correlation with neuron's size. Under current-clamp mode, 'depolarizing sag' was observed in all neurons with I(h) current. The reversal potential (V(rev)) and the maximal conductance density of I(h) (G(h.max-density)) were -31.0 +/- 4.8 mV and 0.17 +/- 0.02 nS/pF, with a half-activated potential (V(0.5) = -99.4 +/- 1.1 mV) and a slope factor (kappa = -10.2 +/- 0.3 mV). There was a correlation between neuron's size and G(h.max-density) only. According to the effect of hypoxia on resting membrane potential, there were hypoxia-sensitive and hypoxia-insensitive neurons. In the hypoxia-sensitive neurons, I(h) was fully abolished by hypoxia, although the resting membrane potential was hyperpolarized. V(0.5) and V(rev) were shifted about 30 mV toward hyperpolarization, whereas G(h.max-density) and kappa were not affected by hypoxia. We suggest that the kinetics and voltage-dependent characteristics of I(h) are varied in mouse DRG neurons with different size. Hypoxia inhibits I(h) in the hypoxia-sensitive neurons by shifting its activation potential to a more hyperpolarized level.

Animals↗

Excitatory effects of gastric electrical stimulation on gastric distension responsive neurons in ventromedial hypothalamus (VMH) in rats.

INTRODUCTION: Gastric electrical stimulation (GES) has been used for the treatment of obesity with unclear central mechanisms. The purpose of this study was to investigate the effects of GES on the neuronal activity in the ventromedial hypothalamus (VMH). METHODS: Extracellular potentials of single neurons in VMH were recorded in 52 anesthetized rats. Neurons were classified as gastric distension-excitatory (GD-E) neurons or GD-inhibitory (GD-I) neurons. GES with four sets of parameters was applied for comparison. RESULTS: Eighty two neurons out of 96 (85.41%) in VMH responded to gastric distension (GD). 37.8% were GD-E neurons and 51(62.2%) were GD-I neurons. 55.0%, 17.6%, 77.8%, 14.3% of GD-E neurons were excited by four sets of parameters: GES1 (standard), GES2 (reduced pulse numbers), GES3 (increased pulse width) and GES4 (reduced frequency), respectively. More GD-E neurons were excited by GES3 (P < 0.05 versus GES2 or GES4) and by GES1 (P < 0.02 versus GES2 or GES4). Among the GD-I neurons, 63.6, 37.9, 73.3, and 51.9% neurons were excited by GES1-4, respectively. CONCLUSION: GES with parameters used for treating obesity excites GD-responsive neurons in VMH. The excitatory effect of GES is related to the strength of stimulation, including pulse frequency and width as well as pulse train on-time.

Action Potentials↗

Development of transformation system of rice based on binary bacterial artificial chromosome (BIBAC) vector.

An Agrobacterium-mediated transformation protocol using binary bacterial artificial chromosome (BIBAC) vector system in rice (Oryza sativa L.) was developed. Calli derived from mature embryos of japonica rice cv. H1493 were used as target tissues. Various aspects in transformation and regeneration processes including callus induction and culture, Agrobacterium concentration and duration of co-cultivation, bacterial elimination and transformant selection were examined in order to improve the transformation efficiency. An optimized transformation conditions was established including: using an Agrobacterium strain, LBA4404(HP4404), which carries a super-virulent helper plasmid pCH32, for the infection; a modified N6 medium system for callus induction and culture; pH 5.6 for media in pre-cultivation and co-cultivation; Agrobacterium concentration at OD600 = 1.0 for 3 days co-cultivation and 7 days for a resting period of the infected calli. Based on PCR and Southern blot analysis, it was demonstrated that insert DNA and marker genes carried by BIBAC2 were integrated into the rice genome.

Chromosomes, Artificial, Bacterial↗

Central mechanisms of gastric electrical stimulation involving neurons in the paraventricular nucleus of the hypothalamus in rats.

BACKGROUND: Gastric electrical stimulation (GES) has been shown to be effective in inducing satiety in patients with obesity, as well as in treating nausea and vomiting in patients with gastroparesis. It is conceivable that these effects are mediated via the central nervous system, although there is a lack of studies or evidences. The aims of this study were to investigate the effects of GES with different parameters on neurons in the paraventricular nucleus (PVN) of the hypothalamus and to study whether the neuronal response was related to stimulation parameters. METHODS: Extracellular potentials of single neurons in the PVN were recorded in anesthetized rats at baseline, during gastric distention (GD) and during GES with various sets of parameters. RESULTS: Of 115 PVN neurons tested by GD, 104 were GD-responsive neurons. Most of these GD-responsive neurons were responsive to GES of various parameters. 1) GES with parameters used in treating obesity, activated neurons both excited (GD-E) and inhibited (GD-I) by gastric distention; it excited 48.4% (16/33) of the GD-E neurons and 60.4% (29/48) of GD-I neurons. 2) GES with increased pulse width was of the highest efficacy in exciting the GD-responsive neurons, whereas a reduction in stimulation frequency resulted in a lower activation. 3) GES with parameters used in treating gastroparesis solicited neuronal responses opposite to those with parameters used for treating obesity. CONCLUSION: GES activates gastric-related neurons in the PVN, and the excitatory effect of GES seems related to stimulation strength. The GES used for treating gastroparesis and the GES used for treating obesity seem to solicit different neuronal responses in the PVN.

Animals↗

Implantable gastric stimulation alters expression of oxytocin- and orexin-containing neurons in the hypothalamus of rats.

BACKGROUND: Implantable gastric stimulation (IGS) has been proposed as a therapeutic option for treating obese patients. We studied the underlying central mechanism behind the reduction of food intake and body weight by gastric electrical stimulation (GES), by studying the expression of anorexigenic and orexigenic-peptide containing neurons in the hypothalamus. METHODS: Oxytocin antiserum, orexin antiserum and c-Fos protein-antiserum were used for immunostaining technique. Brain sections were obtained from the control rats and those with 2 hours of GES with parameters typically used in the treatment of obesity in humans. RESULTS: A) 2-hr IGS increased the expression of oxytocin-immunoreactive (IR) neurons in the paraventricular nucleus (PVN, 23.7+/-1.8 vs 31.1+/-2.2, P<0.05) and the supraoptic nucleus (SON, 29.0+/-2.2 vs 39.7+/-2.5, P<0.01). However, the expression of orexinIR neurons in the lateral hypothalamic area (LHA) was decreased (27.8+/-2.6 vs 20.6+/-1.7, P<0.01). B) The expression of c-Fos positive neurons was increased in the PVN and SON with IGS. A coexistence of oxytocin-IR positive neurons and c-Fos-IR ones in the PVN and SON from the adjacent brain sections was observed, confirming the activation of OT-containing neurons in the PVN and SON following IGS. CONCLUSION: IGS increases the expression of hypothalamic neurons containing the anorexigenic neuropeptide, oxytocin, and decreases the expression of neurons containing the orexigenic neuropeptide, orexin. This central anorexigenic effect of GES may contribute to the reduced appetite and increased satiety in obese patients with IGS therapy.

Animals↗

Intermolecular packing and alignment in an ordered beta-hairpin antimicrobial peptide aggregate from 2D solid-state NMR.

The aggregation and packing of a membrane-disruptive beta-hairpin antimicrobial peptide, protegrin-1 (PG-1), in the solid state are investigated to understand its oligomerization and hydrogen-bonding propensity. Incubation of PG-1 in phosphate buffer saline produced well-ordered nanometer-scale aggregates, as indicated by 13C and 15N NMR line widths, chemical shifts, and electron microscopy. Two-dimensional 13C and 1H spin diffusion experiments using C-terminus strand and N-terminus strand labeled peptides indicate that the beta-hairpin molecules in these ordered aggregates are oriented parallel to each other with like strands lining the intermolecular interface. In comparison, disordered and lyophilized peptide samples are randomly packed with both parallel and antiparallel alignments. The PG-1 aggregates show significant immobilization of the Phe ring near the beta-turn, further supporting the structural ordering. The intermolecular packing of PG-1 found in the solid state is consistent with its oligomerization in lipid bilayers. This solid-state aggregation approach may be useful for determining the quaternary structure of peptides in general and for gaining insights into the oligomerization of antimicrobial peptides in lipid bilayers in particular.

Algorithms↗