Biomedical subjects

Xiuqin Dong

Publications and source records attributed to Xiuqin Dong.

7 recordsLinked to original sources

PubMed2006

Maximum tolerable dose for avoidance of cataract after repeated exposure to ultraviolet radiation in rats.

The purpose of the present study was to determine the impact of inter-exposure interval between repeated equivalent exposures of ultraviolet radiation (UVR) on threshold accumulated dose for cataract development. Female Sprague-Dawley rats were randomly divided into 5 inter-exposure interval groups with 20 rats in each group. The inter-exposure intervals were 6 h, 1, 3, 9 and 30 days respectively. Each inter-exposure interval group was divided into 5 dose-subgroups. Only one eye of each rat was exposed to ultraviolet radiation (lambdamax=300 nm). The total dose incident on the cornea, in each subgroup varied between 0 approximately 10 kJ/m2. One week after the second exposure, the rats were sacrificed and both lenses were extracted. The intensity of forward light scattering was measured and macroscopic morphology was documented. Maximum tolerable dose (MTD) for each inter-exposure interval was estimated based on the experimentally determined dose-response function. The difference of intensity of light scattering between exposed and contralateral non-exposed lens decreased as a function of inter-exposure interval between the two equivalent exposures. The accumulated MTD2.3:16 was 5.3, 5.1, 5.4, 5.8, and 6.0 kJ/m2 UVR-B for the 6 h, 1, 3, 9 and 30 day inter-exposure interval between the two exposures, respectively. The shorter the inter-exposure interval between two subsequent exposures, the more damage. The time constant for repair of lens damage after in vivo exposure to close to threshold dose was estimated to be eight days and the fraction of repairable damage to be 20%. The accumulated threshold dose for damage after two repeated equivalent exposures to UVR-B increases as a function of inter-exposure interval up to at least 30 days inter-exposure interval.

Animals↗

PubMed2006

Biological response in various compartments of the rat lens after in vivo exposure to UVR-B analyzed by HR-MAS 1H NMR spectroscopy.

PURPOSE: The purpose of the present study was to investigate metabolic changes in different compartments of the rat lens (anterior, nuclear, posterior, and equatorial) after exposure to an acute double threshold dose of ultraviolet-B radiation (UVR-B) by using high-resolution magic angle spinning (HR-MAS) (1)H nuclear magnetic resonance (NMR) spectroscopy and pattern recognition (PR) METHODS: methods. One eye in each of 28 6-week-old female albino Sprague-Dawley rats was exposed to in vivo 7.5 kJ/m2 UVR-B for 15 minutes. The contralateral eye was left unexposed. One week after irradiation, all rats were killed, and both lenses were isolated. Each lens was cored by a trephine, and the cylinder was sliced into three portions (anterior, nuclear, and posterior). The lens material that remained after the coring process was analyzed as the equatorial region. Analysis of lens metabolism was performed by HR-MAS 1H NMR spectroscopy (14.1 T; Avance DRX600; Bruker BioSpin GmbH, Rheinstetten, Germany), and the metabolic profiles were statistically analyzed by the PR method of principal component analysis (PCA). RESULTS: Metabolic differences were detected among the compartments in the lens, both in samples from the contralateral nonexposed lenses and in samples from lenses exposed to in vivo UVR-B. In the rat lens, exposure to UVR-B caused changes in GSH, phosphocholine, myo-inositol, succinate, formate, and adenosine triphosphate (ATP)/adenosine diphosphate (ADP) and in levels of the amino acids phenylalanine, taurine, hypo-taurine, tyrosine, alanine, valine, isoleucine, and glutamate, that varied among lens compartments. CONCLUSIONS: HR-MAS 1H NMR spectroscopy, combined with PR methods (PCA), is effective for analysis of separate parts of the intact rat lens. To understand the biochemistry of the lens, it is important to divide the lens into sections, representing functionally and anatomically distinct compartments.

Adenosine Diphosphate↗

PubMed2005

The effect of exposure time on maximum acceptable dose for avoidance of ultraviolet radiation-induced cataract.

The effect of exposure time on maximum acceptable dose (MAD) for avoidance of ultraviolet radiation B (UVRB)-induced cataract was investigated. Sprague-Dawley rats were divided into 5 exposure time groups: 7.5, 15, 30, 60, and 120 min. Each exposure time group was divided into 5 dose subgroups: 0, 1, 2, 4, and 8 kJ/m2. The rats were unilaterally exposed to UVR around 300 nm. One week after the exposure, macroscopic structure was recorded and lens forward light scattering was measured. MAD for avoidance of UVRB-induced cataract was estimated based on the dose-response function. MAD for avoidance of UVRB-induced cataract for 7.5, 15, 30, 60, and 120 min exposures was estimated to be 2.0, 1.4, 1.9, 1.8 and 2.2 kJ/m2, respectively. In the exposure time domain 7.5-120 min, MAD for avoidance of UVRB-induced cataract depends on exposure time.

Animals↗

PubMed2005

Maximum tolerable dose for avoidance of cataract induced by ultraviolet radiation-B for 18 to 60 week old rats.

The purpose of the present study was to investigate the maximum tolerable dose for avoidance of UVR-B-induced cataract in rats in the age interval 18-60 weeks and establish the functional relationship between age and sensitivity to UVR-B. Four groups of 20 albino Sprague-Dawley rats each, aged 18, 26, 40 or 60 weeks, were included. Each age group was divided into five UVR dose sub-groups. The rats were unilaterally exposed to ultraviolet radiation (lambda(max)=302.6 nm, lambda0.5=4.5 nm). The incident dose on the cornea varied between 0 and 9.2 kJ m(-2). One week after exposure, the rats were sacrificed and both lenses were extracted. The intensity of forward light scattering was measured and photographs were taken. The functional relationship between age and sensitivity to UVR-B was estimated as the maximum tolerable dose based on rats age from 3 to 60 weeks. The maximum tolerable dose for 18, 26, 40, and 60 weeks, respectively, was estimated to 5.2, 4.9, 4.7, and 5.1 kJ m(-2). The sensitivity to UVR-B for Sprague-Dawley rats increases with increasing age during the first third of the rat life span, and then stabilizes to a constant level during the remaining two-thirds.

Aging↗

PubMed2005

UVR-B induced cataract development in C57 mice.

The evolution of the morphological appearance and intensity of light scattering in C57 mice lenses after exposure to ultraviolet radiation type B (UVR-B) was investigated. A total of 80, 6-week-old female C57BL/6 mice were divided into four groups (n=20). One eye in each animal was exposed in vivo to UVR-B in the 300 nm wavelength region (UVR-B-300 nm) to a dose of 5 kJm(-2) for 15 min. The radiation output had lambda(max) at 302 nm with 5 nm [FWHM]. The animals were consecutively sacrificed at 1, 2, 4 and 8 days after the exposure. Macroscopic lens changes were documented using grid- and dark field illumination photography. Light scattering in the exposed and contralateral not exposed lens was measured quantitatively. Morphological lens changes were documented using grid- and dark field illumination photography. In vivo exposure to UVR-B-300 nm induced subcapsular cataract in all exposed lenses and occasionally cortical and nuclear cataract at all investigated time points. Exposed lenses scattered light significantly higher on all investigated days compared to contralateral non-exposed lenses. A transient increase of light scattering peaking at day 2 in exposed as well as in contralateral not exposed lenses was identified. Light scattering of the lenses varies with latency time after exposure. A dose of 5 kJm(-2) UVR-B-300 nm induces light scattering in C57 mice lenses. The increase has a transient peak at 2 days after exposure. The variation of light scattering among days 1, 2, 4, and 8 indicates a dynamic change of scattering characteristics in the mouse lens following unilateral in vivo exposure to 5 kJm(-2) UVR-B-300 nm.

Animals↗

PubMed2003

Ultraviolet radiation-induced cataract: age and maximum acceptable dose.

PURPOSE: To investigate the effect of age on ultraviolet radiation-B (UVR-B)-induced cataract and to detect the maximum acceptable dose in rats of different age groups. METHODS: Four age groups of 20 rats each, aged 3, 6, 10, and 18 weeks, were included. Each age group was divided into five UVR-B dose subgroups. The rats were unilaterally exposed to UVR-B (lambda(max) = 302.6 nm, lambda(0.5) = 4.5 nm). The incident dose on the cornea varied between 0 and 8 kJ/m(2). One week after exposure, the rats were killed, both lenses were extracted, the intensity of forward light-scattering was measured, and photographs were taken. The sensitivity of the lens to UVR-B was estimated as the maximum acceptable dose. RESULTS: The maximum acceptable dose for 3-, 6-, 10-, and 18-week-old rats was estimated to be 1.4, 2.7, 4.3 and 5.2 kJ/m(2), respectively. CONCLUSIONS: Young rats were more sensitive to UVR-B than old ones. Age should be considered when estimating the risk for UVR-B-induced cataract.

Aging↗

PubMed2002

Forceps-guided nuclear cleavage cataract extraction.

We introduce a manual nuclear fragmentation technique, forceps-guided nuclear cleavage. A 5.5 to 7.0 mm superior scleral incision is started 1.5 mm posterior to the limbus. Two additional 1.0 mm paracenteses are made at 3 and 9 o'clock in clear cornea close to the limbus. A continuous curvilinear capsulorhexis (CCC) is created; in most cases, 4 to 5 radial relaxing incisions are made in the CCC. The anterior and equatorial cortex and epinucleus are removed with 2-handed irrigation/aspiration via the 2 paracenteses with the nucleus in the capsular bag. The nucleus is prolapsed into the anterior chamber. A nucleus hook is inserted via the 3 o'clock paracentesis and applied to the 6 o'clock nuclear equator to hold the nucleus. A nucleus cleaving forceps is inserted through the upper incision to the 12 o'clock equator of the nucleus and advanced to one-third depth of the nucleus. The forceps is relaxed while the nucleus is cleaved in half.

Aged↗