Biomedical subjects

Guojun Zhang

Publications and source records attributed to Guojun Zhang.

10 recordsLinked to original sources

PubMed2026

CRISPR/Cas- and Argonaute-Based In Vivo Nucleic-Acid Imaging Technologies: Strategies, Challenges, and Perspectives.

Live-cell monitoring of sequence-specific nucleic acids is essential to understanding genome organization, RNA regulation, and disease progression. Clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein (Cas) and Argonaute (Ago) systems provide programmable, guide-directed recognition of DNA or RNA and are increasingly used as platforms for in vivo bioimaging. This review summarizes the structural and mechanistic features of representative CRISPR and Ago effectors and discusses design strategies for sensitive, specific, and multiplexed imaging of genomic loci, extrachromosomal DNA, and endogenous RNA in living cells. We compare the analytical performance and limitations of CRISPR- and Ago-based imaging, with particular emphasis on the major technical and biological challenges affecting their accuracy, applicability, and reliability. Finally, this review offers insights into developing high-resolution and user-friendly bioimaging platforms for fundamental biology and future translational applications.

CRISPR↗

PubMed2006

Enhancing GABA(A) receptor alpha 1 subunit levels in hippocampal dentate gyrus inhibits epilepsy development in an animal model of temporal lobe epilepsy.

Differential expression of GABA(A) receptor (GABR) subunits has been demonstrated in hippocampus from patients and animals with temporal lobe epilepsy (TLE), but whether these changes are important for epileptogenesis remains unknown. Previous studies in the adult rat pilocarpine model of TLE found reduced expression of GABR alpha1 subunits and increased expression of alpha4 subunits in dentate gyrus (DG) of epileptic rats compared with controls. To investigate whether this altered subunit expression is a critical determinant of spontaneous seizure development, we used adeno-associated virus type 2 containing the alpha4 subunit gene (GABRA4) promoter to drive transgene expression in DG after status epilepticus (SE). This novel use of a condition-dependent promoter upregulated after SE successfully increased expression of GABR alpha1 subunit mRNA and protein in DG at 1-2 weeks after SE. Enhanced alpha1 expression in DG resulted in a threefold increase in mean seizure-free time after SE and a 60% decrease in the number of rats developing epilepsy (recurrent spontaneous seizures) in the first 4 weeks after SE. These findings provide the first direct evidence that altering GABR subunit expression can affect the development of epilepsy and suggest that alpha1 subunit levels are important determinants of inhibitory function in hippocampus.

Animals↗

PubMed2006

Increased GABA(A)-receptor alpha1-subunit expression in hippocampal dentate gyrus after early-life status epilepticus.

PURPOSE: Previous studies in neonatal (postnatal day 10) and adult rats suggest that status epilepticus (SE) induces changes in the alpha1 subunit of the GABA(A) receptor (GABRA1) in dentate granule neurons (DGNs) that are age dependent and vary inversely with the likelihood of epilepsy development. In the present study, we examined GABRA1 expression after SE at postnatal day 20 (P20), an intermediate age when only a subset of SE-exposed animals develop epilepsy. METHODS: SE was induced with lithium-pilocarpine or kainate at P20. Animals were video-EEG monitored after SE to determine the presence or absence of spontaneous seizures. GABRA1 mRNA and protein levels were determined 7 days or 3 months later in SE-exposed and control animals by using a combination of aRNA amplification, Western blotting, and immunohistochemistry techniques. RESULTS: GABRA1 mRNA levels in DGNs of SE-exposed rats that did not become epileptic were higher than those in control rats, but were not different from DGNs in epileptic SE-exposed rats. GABRA1 protein levels in dentate gyrus were significantly increased in both epileptic and nonepileptic SE-exposed rats compared with controls. GABRA1 mRNA changes were region specific and did not occur in CA1 or CA3 areas of hippocampus. GABRA1 alterations were present by 1 week after P20 SE and were similar whether pilocarpine or kainate was used to induced SE. CONCLUSIONS: P20 SE results in persistent increases in GABRA1 levels selectively in dentate gyrus. These changes preceded the onset of epilepsy, were not model specific, and occurred in both epileptic and nonepileptic animals.

Animals↗

PubMed2005

Process kinetics of inoculation composting of municipal solid waste.

A method was used to improve the composting efficiency by seeding with Inoculum A (a blend of Bacillus azotofixams, Bacillus megaterium and Bacillus mucilaginosus), Inoculum B (a blend of effective cellulolytic strains, i.e. Trichoderma koningii, Streptomyces cellulosae, and White-rot fungi), and Inoculum C (a mixture of Inoculum A and Inoculum B). There were four runs: the control run (not inoculated), Run A, Run B and Run C. During the runs, parameters such as temperature, O2, CO2 and H2S emissions, and microbial concentration were investigated to study the efficiencies of inoculation composting. The maximum oxygen uptake rates in the control run, Run A, Run B and Run C were calculated as 0.22, 0.32; 0.28 and 0.34 mol/hkg while the corresponding total O2 quantities accumulated were 511.18, 684.57, 659.74 and 778.47 g/hkg, respectively. In addition, odorous gases were highly reduced by inoculation. In order to understand the mechanisms of inoculation composting process, two stages kinetics equations were developed from the viewpoint of microbial kinetics. These equations showed that, in the first stage, microbial concentration was the main limiting factor of the degradation rate. The degradation rates in control, Run A, Run B and Run C were 10.5, 13.61, 13.08, and 15.671 g/kgh, respectively. In the second stage, the degradation rate was mainly affected by substrate concentration. Although the degradation rates were at almost the same level for both with and without inoculation, inoculation could reduce the half velocity coefficient K(m) and in turn stabilize the composting products efficiently. Therefore, inoculation could improve the efficiency of the composting process.

Bacillus↗

PubMed2005

An epileptic seizure prediction algorithm based on second-order complexity measure.

The quality of life of many epilepsy patients may be improved significantly if the occurrence of epileptic seizures can be successfully forecasted and clinical intervention, such as electrical stimulation or drug delivery, can then be used to suppress their emergence, or warn the patient of the forthcoming events. In this paper, a prediction algorithm based on the second-order complexity measure was proposed to predict the impending seizures. Through the analysis of long-term intracranial EEG recordings from two frontal lobe epilepsy patients, the results indicated that the sensitivity of prediction was 77.8% (14/18) and 66.7% (4/6) and the number of false warnings was 3 and 2 for the two patients, respectively. Because only the information of past seizures was utilized to predict the current seizure and the computation load was low, the prediction algorithm could possibly be applied to clinical practice.

Adolescent↗

PubMed2005

Heterogeneous GABAA receptor subunit expression in pediatric epilepsy patients.

The gamma-amino-butyric acid type A receptors (GABAAR) are a heteropentameric receptor complex, composed of 16 possible subunits in various combinations, forming a ligand-gated ion channel. Subunit composition is the primary determinant of GABAAR physiology and pharmacology. Here we have measured mRNA levels for 16 GABAAR subunits in isolated dentate granule neurons (DGN) from eight pediatric patients undergoing resective surgery for intractable epilepsy. We found tightly correlated expression of a subset of GABAAR subunit mRNAs within a single DGN (alpha1, gamma1, and gamma2; alpha4, alpha5, and beta2; alpha4 and beta3). Analysis of inter-patient variability (ANOVA) of eleven highly expressed GABAAR subunit mRNAs found seven of the subunits varied between patients, as did whole cell GABAAR currents. Due to inter-patient differences, there is heterogeneity in DGN GABAAR subunit mRNA and physiology within pediatric epilepsy patients. Patient-specific GABAAR expression might contribute to variability in anti-epileptic drug efficacy, side-effect profiles, and seizure susceptibility.

Adolescent↗

PubMed2004

Post-treatment of banknote printing works wastewater ultrafiltration concentrate.

A novel process of vortex settling and stage-2 ultrafiltration (UF) with alternating feed direction was used to further concentrate the concentrate produced by a stage-1 UF employed for treatment of banknote printing works wastewater. In this post-treatment process, the final concentrate volume for incineration was reduced by 4-5 times while the permeate of the stage-2 UF could be further reused in the banknote printing operation. It was noted vortex settling facilitated settling of the printing ink and the strategy of regularly alternating feed direction in the UF resulted in a higher permeate flux compared to the corresponding flux for operation without alternating feed direction. The hydraulic retention time (HRT) of the vortex settling tank (VST) used in the pilot-scale experiment was 14 min while feed direction to the stage-2 UF was alternated once every hour. Based on the pilot-scale experimental results, a full-scale system was set up. An economic analysis showed that the novel system was a cost-effective option for post-treatment of stage-1 UF concentrate. The treatment system has been successfully implemented at several Chinese banknote printing companies.

Coloring Agents↗

PubMed2004

Long-term alterations in glutamate receptor and transporter expression following early-life seizures are associated with increased seizure susceptibility.

Prolonged seizures in early childhood are associated with an increased risk of development of epilepsy in later life. The mechanism(s) behind this susceptibility to later development of epilepsy is unclear. Increased synaptic activity during development has been shown to permanently alter excitatory neurotransmission and could be one of the mechanisms involved in this increased susceptibility to the development of epilepsy. In the present study we determine the effect of status-epilepticus induced by lithium/pilocarpine at postnatal day 10 (P10 SE) on the expression of glutamate receptor and transporter mRNAs in hippocampal dentate granule cells and protein levels in dentate gyrus of these animals in adulthood. The results revealed a decrease in glutamate receptor 2 (GluR2) mRNA expression and protein levels as well as an increase in protein levels for the excitatory amino acid carrier 1 (EAAC1) in P10 SE rats compared to controls. Expression of glutamate receptor 1 (GluR1) mRNA was decreased in both P10 SE rats and identically handled, lithium-injected littermate controls compared to naive animals, and GluR1 protein levels were significantly lower in lithium-controls than in naive rats, suggesting an effect of either the handling or the lithium on GluR1 expression. These changes in EAA receptors and transporters were accompanied by an increased susceptibility to kainic acid induced seizures in P10 SE rats compared to controls. The current data suggest that early-life status-epilepticus can result in permanent alterations in glutamate receptor and transporter gene expression, which may contribute to a lower seizure threshold.

Amino Acid Transport System X-AG↗

PubMed2003

[Study on assistant cleaning of ultrasound for the ultrafiltration membrane].

The effects of ultrasounds with different frequency on membrane performance were investigated in this paper. The experimental results show that there were nearly no effects of 20 W ultrasound on membrane retention coefficient, but it decreased seriously when the ultrasound power was above 30 W. On the basis of these results, low frequency ultrasound (20 W) was introduced to assist the chemical cleaning in the ultrafiltration process of wastewater from bank note printing works. The cleaning time could be shortened from 20-30 min to 5 min by the ultra-liberation and ultra-blend effects of ultrasound, therefore, the cleaning efficiency was highly improved. However, the fouling substances could not be cleaned entirely in the simple physical cleaning process by SEM analysis.

Industrial Waste↗

PubMed2002

[Relationship between the heterotopic neurons and intractable epilepsy].

OBJECTIVE: To discuss the relationship between heterotopic neurons and intractable epilepsy. METHODS: Epileptogenic zones were precisely located with MRI, video-EEG monitoring, intracranial electrical recording and electrocorticography monitoring and then resected in seven patients. The removed tissue was processed for conventional pathological examination with immunohistochemical staining. RESULTS: Heterotopic neurons were found in the white matter of the specimens. All the seven cases experienced a favorable outcome, with six seizure free. CONCLUSION: The heterotopic neurons scattered or clustered in the white matter contribute to the pathogenesis of intractable epilepsy.

Adolescent↗