Publications by authors named "Tai Zheng"

7 Publications

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[Quantitative assess the efficacy of congenital idiopathic nystagmus surgery by digital eye tracker].

Zhonghua Yan Ke Za Zhi 2015 Jun;51(6):439-44

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Objective: To evaluate the feasibility of independently developed digital eye tracker in determining the efficacy of congenital idiopathic nystagmus (CIN) surgery.

Methods: Aprospective selfpairing study. The surgical efficacy was evaluated by independently developed eye tracker in 16 CIN patients. The null zone and the frequency, amplitude, intensity of nystagmus in various gazing position were recorded with eye tracker pre and post operatively. The consistency of null zone determined by digital eye tracker and clinical investigation were evaluated. The preoperative and postoperative rectification of horizontal and vertical nystagmus in the horizontal direction of individual patient were compared by paired samples t-test. The improvement or aggravation quantity were recorded by comparing preoperative and postoperative intensity of nystagmus every 5° within 25°.

Result: The null zone got from digital eye tracker and clinical investigation were highly consistent (r = 0.952, P < 0.01). The horizontal and vertical intensity improved in 9 patients (t = 2.335-6.609, P < 0.05) and 5 patients (t = 2.176-5.471, P < 0.05) respectively after surgery. There were 67.63% (117/173) horizontal intensity and 69.94% (121/173) vertical intensity improvement.

Conclusion: The independently developed digital eye tracker can quantitatively evaluate the pre and post-operative nystagmus and analyze the surgical efficacy for CIN patients.
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June 2015

Effect of artificial scotomas on open-loop disparity vergence eye movements.

Optom Vis Sci 2015 Jan;92(1):107-14

*MD, PhD †MD ‡PhD Department of Ophthalmology, Shanghai Children's Hospital, Jiaotong University, Shanghai, China (DY, ZT); Vision Center, Department of Ophthalmology, The Children's Hospital of Akron, Northeast Ohio Medical University, Akron, Ohio (DY, RWH, MK); Optometry Centre, School of Chemical and Life Sciences, Singapore Polytechnic, Singapore, Singapore (MZ); and Department of Biomedical Engineering, University of Minnesota, Twin Cities, Minneapolis, Minnesota (EH).

Purpose: To investigate the effect of an artificial scotoma on open-loop disparity vergence responses (DVRs) and vergence control mechanisms, we examined open-loop DVRs to disparity stimuli using monocular artificial scotomas in normal subjects.

Methods: Using a mirror haploscope with two computer monitors, we delivered disparity stimuli on a pair of random dot patterns subtending 40 by 30 degrees at 47 cm from each eye. The scotomas were black circles located in the center of a random dot pattern for the left eye. Eye movements of both eyes were recorded with a magnetic search coil system.

Results: We first found that the amplitudes of DVRs were gradually decreased and the latency of DVRs was moderately increased as the size of the scotomas was increased. Second, monocular responses from each eye were symmetrical although the stimuli to each eye were asymmetrical.

Conclusions: The results suggest that the monocular eye movements in disparity vergence are controlled by a binocular central mechanism, not driven separately by monocular inputs in the open-loop window.
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http://dx.doi.org/10.1097/OPX.0000000000000441DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4286429PMC
January 2015

Direct observation of dynamic mechanical regulation of DNA condensation by environmental stimuli.

Angew Chem Int Ed Engl 2014 Sep 21;53(40):10631-5. Epub 2014 Aug 21.

Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742 (USA).

Gene delivery is a promising way to treat hereditary diseases and cancer; however, there is little understanding of DNA:carrier complex mechanical properties, which may be critical for the protection and release of nucleic acids. We applied optical tweezers to directly measure single-molecule mechanical properties of DNA condensed using 19-mer poly-L-lysine (PLL) or branched histidine-lysine (HK) peptides. Force-extension profiles indicate that both carriers condense DNA actively, showing force plateaus during stretching and relaxation cycles. As the environment such as carrier concentration, pH, and the presence of zinc ions changes, DNA:HK complexes showed dynamically regulated mechanical properties at multiple force levels. The fundamental knowledge from this study can be applied to design a mechanically tailored complex which may enhance transfection efficiency by controlling the stability of the complex temporally and spatially.
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http://dx.doi.org/10.1002/anie.201403499DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5517097PMC
September 2014

A new measure of nystagmus acuity.

Int J Ophthalmol 2014 18;7(1):95-9. Epub 2014 Feb 18.

Department of Ophthalmology, Southwest Hospital, Third Military Medical University, Chongqing 400038, China ; Chongqing Key Lab of Visual Damage and Regeneration & Restoration, Chongqing 400038, China.

Aim: To construct a new visual acuity measuring function for congenital nystagmus (CN) patients by studying the relationships between acuity, velocities and positions of the eye.

Methods: After assessing the relationship between acuity, movement velocities and positions of the eye separately, a new function, which we call the automated nystagmus acuity function (ANAF), was constructed to measure the visual acuity of CN patients. Using a high-speed digital video system working at 500 frames per second, each eye was calibrated during monocular fixation. Twenty-six recorded nystagmus data were selected randomly. Using nystagmus waveforms, the best vision position (foveation period) and visual acuity were analyzed in three groups of subjects, and then all outputs were compared with the well-known expanded nystagmus acuity function (NAFX) and ANAF. Standard descriptive statistics were used to summarize the outputs of the two programs.

Results: Foveation periods were brief intervals in the CN waveform when the image was on or near the fovea and eye velocity was relatively slow. Results showed good visual acuity happened during the period when velocity was low and the eye position was near the zero position, which fitted the foveation periods. The data analyzed with NAFX and ANAF had a correlation coefficient of 0.934276, with an average error of -0.00973.

Conclusion: The results from ANAF and NAFX analyses showed no significant difference. The NAFX manually identifies foveation eye positions and produces accurate measurements. The ANAF, however, can be calculated simply using the factors eye position and velocity, and it automatically calculates the ANAF without the need to manually identify foveation eye positions.
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http://dx.doi.org/10.3980/j.issn.2222-3959.2014.01.17DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3949466PMC
March 2014

Identification of small molecule activators of the janus kinase/signal transducer and activator of transcription pathway using a cell-based screen.

Biol Pharm Bull 2012 ;35(1):65-71

Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, PR China.

Type I interferons (IFN-α/β) have been widely used in the treatment of many viral and malignant diseases by activation of the Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway, but the side effects of protein-based IFN therapy severely limit their clinical use. Discovering small molecules to activate the JAK/STAT pathway will greatly facilitate the development of new drugs which have similar pharmacological function to IFNs but with fewer side effects. To screen a natural products-based library, we established a cell-based screening assay using human hepatoma HepG2 cells stably transfected with a plasmid where the luciferase reporter activity is driven by interferon α-stimulated response element (ISRE), the motif specifically recognized by type I IFN-induced activation of JAK/STAT pathway. Among 1,431 natural product compounds screened, four compounds (emodin, quercetin, apigenin and luteolin) were identified as activators of the JAK/STAT pathway. Further studies demonstrated that these four compounds could increase the endogenous antiviral gene expression regulated by the IFN-activated JAK/STAT pathway. The identified small molecule activators are valuable for structural modification and warrant further investigation for use in new antiviral drugs as IFN mimics or adjuvants.
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http://dx.doi.org/10.1248/bpb.35.65DOI Listing
June 2012

A new algorithm for automated nystagmus acuity function analysis.

Br J Ophthalmol 2011 Jun 7;95(6):832-6. Epub 2010 Nov 7.

The Laboratory of Visual and Ocular Motor Neurophysiology, The UPMC and Children’s Eye Center, Department of Ophthalmology, Pediatric Ophthalmology, The Children’s Hospital of Pittsburgh, University of Pittsburgh, USA.

Aims: We developed a new data analysis algorithm called the automated nystagmus acuity function (ANAF) to automatically assess nystagmus acuity function. We compared results from the ANAF with those of the well-known expanded nystagmus acuity function (NAFX).

Methods: Using the ANAF and NAFX, we analysed 60 segments of nystagmus data collected with a video-based eye tracking system (EyeLink 1000) from 30 patients with infantile or mal-development fusional nystagmus. The ANAF algorithm used the best-foveation positions (not true foveation positions) and all data points in each nystagmus cycle to calculate a nystagmus acuity function.

Results: The ANAF automatically produced a nystagmus acuity function in a few seconds because manual identification of foveation eye positions is not required. A structural equation model was used to compare the ANAF and NAFX. Both ANAF and NAFX have similar measurement imprecision and relatively little bias. The estimated bias was not statistically significant for either methods or replicates.

Conclusions: We conclude that the ANAF is a valid and efficient algorithm for determining a nystagmus acuity function.
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http://dx.doi.org/10.1136/bjo.2010.184432DOI Listing
June 2011

A systematic approach to eye muscle surgery for infantile nystagmus syndrome: results in 100 patients.

Binocul Vis Strabismus Q 2010 ;25(2):72-93

The UPMC and Children Hospital of Pittsburgh Eye Centers and The Laboratory of Visual and Ocular Motor Physiology Pittsburgh, PA 15101, USA.

Purpose: To report a systematic approach to, and the visual and electrophysiological effect of, eye muscle surgery in 100 patients with infantile nyustagmus syndrome (INS).

Methods: Prospective, interventional case cohort analysis of clinical and eye movement data in 100 patients with INS who had virgin extraocular eye muscles operated on for nystagmus with or without combinations of strabismus and an anomalous head posture. All patients were followed at least 9 months after surgery. Outcome measures, part of an IRB approved study, included binocular visual acuity, head position, strabismic deviation, and eye movement recordings, from which waveform types and an Automated Nystagmus Acuityn Function (ANAF) was calculated. Computerized parametric and non-parametric statistical analysis of data were performed using standard software on both individual and group data.

Results: There were 9 consistent surgical procedures used with the most common being that for a horizontal head posture alone (22%). Age at surgery averaged 14 years with 11 months followup. Sixty-eight percent had associated eye disease (optic nerve, retinal, amblyopia, cataracts). Group means in binocular acuity, strabismic deviation, head posture, abd ANAF measures from eye improved for all procedures. There were 12 (12%) reoperations without any serious surgical complications. Individual analysis revealed only age and head posture differences in outcome measures between the 9 procedures.

Conclusions: Using this approach, surgery on the extraocular muscles in patients with INS results in improvements in multiple aspects of ocular motor and visual function.
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April 2011
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