Biomedical subjects

Weirong Chen

Publications and source records attributed to Weirong Chen.

6 recordsLinked to original sources

PubMed2005

Discovery of potent 3,5-diphenyl-1,2,4-oxadiazole sphingosine-1-phosphate-1 (S1P1) receptor agonists with exceptional selectivity against S1P2 and S1P3.

A class of 3,5-diphenyl-1,2,4-oxadiazole based compounds have been identified as potent sphingosine-1-phosphate-1 (S1P1) receptor agonists with minimal affinity for the S1P2 and S1P3 receptor subtypes. Analogue 26 (S1P1 IC50 = 0.6 nM) has an excellent pharmacokinetics profile in the rat and dog and is efficacious in a rat skin transplant model, indicating that S1P3 receptor agonism is not a component of immunosuppressive efficacy.

Animals↗

PubMed2005

Practical asymmetric synthesis of a potent PDE4 inhibitor via stereoselective enolate alkylation of a chiral aryl-heteroaryl secondary tosylate.

A practical, chromatography-free catalytic asymmetric synthesis of a potent and selective PDE4 inhibitor (L-869,298, 1) is described. Catalytic asymmetric hydrogenation of thiazole ketone 5a afforded the corresponding alcohol 3b in excellent enantioselectivity (up to 99.4% ee). Activation of alcohol 3b via formation of the corresponding p-toluenesulfonate followed by an unprecedented displacement with the lithium enolate of ethyl 3-pyridylacetate N-oxide 4a generated the required chiral trisubstituted methane. The displacement reaction proceeded with inversion of configuration and without loss of optical purity. Conversion of esters 2b to 1 was accomplished via a one-pot deprotection, saponification, and decarboxylation sequence in excellent overall yield.

3',5'-Cyclic-AMP Phosphodiesterases↗

PubMed2005

[A study of ultrasound biomicroscope in diagnoses of senile cataract].

PURPOSE: To investigate the imaging characteristics of ultrasound biomicroscope (UBM) in the different stages and evaluate preliminary application of UBM in diagnosis of senile cataract. METHODS: Using UBM to examine 80 eyes, which were diagnosed senile cataract by slit-lamp microscope (20 eyes, incipient stage; 20 eyes, intumescent stage; 20 eyes, mature stage; 20 eyes, hypermature stage). RESULTS: The UBM image of senile cataract is distinguished in the different stages. In incipient stage, it shows sporadic flake high echo areas in equator of the lens. In intumescent stage, it shows flake high echo areas and low echo areas interlace each other, and the thickness of equator increases. In mature stage, it shows symmetrical high echo areas in cortex of the lens and higher echo areas in nucleus of the lens sometimes. In hypermature stage, it shows irregular echo (heterogeneous high density glisten) areas of the lens, heterogeneous incrassation and strong echo areas of anterior capsule. Characteristic high echo granules were found in the anterior chamber. The granules may obstruct the anterior chamber angle. CONCLUSION: The UBM examination can be an assistant diagnostic method for senile cataract, especially for the patients whose refractive media of ocular anterior segment is opacity or the pupil is very small.

Aged↗

PubMed2005

[A study on axis length measurement of high myopia with cataract].

PURPOSE: To study the accuracy of axis length measurement on high myopia with cataract. METHODS: A/B scan ultrasonography and IOL-master were used to measure the ocular axial length in 168 high myopic eyes with cataract of 103 cases. B-scan ultrasonography was used to examine posterior scleral staphyloma. Refractive results were recorded during the follow-up after operation to evaluate the accuracy of measurement. RESULTS: The rate of posterior scleral staphyloma was 76.19%. The average postoperative error of refractive of all eyes was between -1.0 D and +1.0 D. CONCLUSION: Accurate data of axis length can be obtained by combining results of A-scan, B-scan ultrasonography and IOL-master for high myopia with cataract, especially for patients with posterior scleral staphyloma.

Aged↗

PubMed2002

[Tear film changes after phacoemulsification].

OBJECTIVE: To evaluate tear film changes after phacoemulsification. METHODS: This prospective randomized study involved 68 consecutive patients with age-related cataract (79 eyes) who underwent phacoemulsification. Tear break-up time, Schirmer I test (S I t) value, corneal fluorescein staining, tear film pattern by DR-1 tear interfermetry and the height of tear meniscus were measured preoperatively and 1 day and 2, 7, 14, 30, 180 days postoperatively. RESULTS: At 1 day and 2 days postoperatively, the mean tear break-up time reduced greatly, and the number of patients who showed III to V tear film pattern, the mean S I t value, the height of tear meniscus and fluorescein staining scores increased significantly (P < 0.001 for day 1, P < 0.005 for day 2). S I t value at 7 days postoperatively (P = 0.831) and the height of tear meniscus at 14 days returned to their preoperative values (P = 1.000). The tear break-up time, corneal fluorescein staining scores and the grades of tear film pattern all recovered at 30 days postoperatively (P > 0.05). At 30 days postoperatively, 19.3% of patients showed shorter tear break-up time and less S I t value than that of preoperative day. In addition, 1/9 of the patients with normal preoperative tear film experienced dry eye at 30 days postoperatively. The cases with tear break-up time < 10 seconds compared to patients with tear break-up time >/= 10 seconds were more easily to show tear instability postoperatively (relative risk 13.5, 8.25, 20.0, 39.0, 8.6, 3.9 at 1 day and 2, 7, 14, 30, 180 postoperative days, respectively). CONCLUSION: Phacoemulsification significantly alters the tear break-up time, S I t value, corneal fluorescein staining, tear film pattern and the height of tear meniscus. Some patients with normal tear film may experience dry eye after surgery. Patients with preexisting tear break-up time < 10 seconds are easily at risk of experiencing the tear film instability postoperatively.

Aged↗

PubMed2002

Late postoperative complication of the foldable lens implantation: opacification of the intraocular lenses.

OBJECTIVE: To analyze the cause of the late postoperative opacification of the lens optic of implanted intraocular lens (IOL). METHODS: Twenty-two foldable hydrophilic acrylic lenses with opacification of their optics in 19 patients were taken out of the eye by surgery and examined by gross examination and microscopy. The lenses were stained with alizarin red and von Kossa method (special stains for calcium). Some were submitted for energy dispersive X-ray spectroscopy and scanning electron microscopy. The same kind of transparent IOLs were examined as the control group. RESULTS: Granular deposits of variable sizes were revealed on the surface and within the lens optics. The deposits that were stained positive with alizarin red and von Kossa method showed the presence of calcium. Energy dispersive X-ray spectroscopy demonstrated the calcium and the phosphate present in the deposits. The distribution of the granules was dense in the central part of the optic and sparse at its periphery. There were negative findings in the haptics of the lenses taken out and the control lenses. CONCLUSION: The cause of the opacification of the foldable lens optics is the deposits that consist of calcium and phosphate occurring inside and on the surface of the optics.

Device Removal↗