Biomedical subjects

Liang Xu

Publications and source records attributed to Liang Xu.

At least 37 records · Page 2Linked to original sources

PubMed2006

Sonocatalytic degradation of methyl parathion in the presence of nanometer and ordinary anatase titanium dioxide catalysts and comparison of their sonocatalytic abilities.

The degradation of methyl parathion (O,O-dimethyl-O-(4-nitrophenyl)-phosphorothioate) using anatase titanium dioxide (TiO(2)) powder as heterogeneous sonocatalysts is reported. The influences of reaction parameters such as the species of TiO(2) sonocatalysts, methyl parathion concentrations, TiO(2) adding amount, pH, ultrasonic intensity, ultrasonic frequency and temperature have been investigated and the optimal conditions for eliminating methyl parathion have been identified. The efficiencies of sonocatalytic degradation in both nanometer and ordinary anatase systems are compared and the results indicate that the sonocatalytic activity of nanometer anatase TiO(2) powder is better than that of ordinary anatase TiO(2) powder. The primary degradation and the total mineralization of methyl parathion have been monitored by high performance liquid chromatography (HPLC) and UV-vis spectra, respectively. Methyl parathion got destroyed to some extent in both nanometer and ordinary anatase systems under ultrasonic irradiation. The kinetics for the degradation process of methyl parathion follows the first-order reaction. The degradation ratio of methyl parathion surpassed 90% within 50min in the optimal experiment conditions.

Catalysis↗

PubMed2006

Determination and pharmacokinetic study of syringin and chlorogenic acid in rat plasma after administration of Aidi lyophilizer.

A high-performance liquid chromatographic (HPLC) method was developed for the first time to simultaneously quantify syringin and chlorogenic acid in rat plasma using wavelength-transfer technology. The analysis was performed on a Diamonsil C(18) column (200 x 4.6 mm i.d., 5 microm particle size) with isocratic mobile phase consisting of acetonitrile-0.05% phosphoric acid (12:88, v/v). The linear ranges were 0.20-10 and 0.25-30 microg/mL, respectively. The lower limits of quantification were 0.20 and 0.25 microg/mL, respectively. The method was shown to be reproducible and reliable with intraday precision below 8.5 and 6.1%, interday precision below 7.1 and 5.5%, accuracy within +/-7.1 and +/-8.6%, and mean extraction recovery excess of 92.1 and 80.9%, respectively, which were all calculated from the blank plasma sample spiked with syringin and chlorogenic acid at three concentrations of 0.20, 1.0 and 6.0 microg/mL for syringin and 0.25, 2.0 and 20 microg/mL for chlorogenic acid. This method was validated for specificity, accuracy and precision and was successfully applied to the pharmacokinetic study of syringin and chlorogenic acid in rat plasma after intravenous administration of Aidi lyophilizer.

Animals↗

PubMed2006

Cytotoxic constituents from Solanum lyratum.

Activity-guided fractionation of the ethanol extract of the whole plant from Solanum lyratum resulted in the isolation of a new pregnane derivative glycoside, 16-dehydropregnenolone 3-O-alpha-L-rhamnopyranosyl-(1 --> 2)-beta-D-glucopyranosid uronic acid (2), as well as other six known compounds: 16-dehydropregnenolone (1), allopregenolone (3), protocatechuic acid (4), vanillic acid (5), caffeic acid (6), and scopoletin (7). The structures of the isolated compounds were elucidated on the basis of their spectral data and chemical evidences. Compounds 1, 3, 4 were isolated for the first time from this plant. Cytotoxic activities of the isolated compounds were evaluated. Compound 1 exhibited significant cytotoxic activity against A375-S2, HeLa, SGC-7901, and Bel-7402 with IC50 values of 13.1 +/- 0.9, 21.5 +/- 1.0, 40.2 +/- 0.7, and 49.8 +/- 1.2 microg/mL, respectively.

Animals↗

PubMed2006

Prevalence of visual impairment among adults in China: the Beijing Eye Study.

PURPOSE: To estimate the prevalence and distribution of blindness and low vision in Northern China. DESIGN: Population-based cohort study. METHODS: The Beijing Eye Study included 4438 subjects with an age of 40+ years. Mean age was 56.2 +/- 10.6 years (range, 40 to 101 years). RESULTS: Forty-three (1.0%) individuals had low vision (<20/60 and >/=20/400 best-corrected vision), and 17 (0.4%) individuals were blind (best-corrected visual acuity in the better-seeing eye <20/400). Low vision/blindness were significantly associated with age (P < .001), myopic refractive error (P < .001), and level of educational background (P = .035). It was not associated with gender (P = .76) and rural vs urban area (P = .88). CONCLUSIONS: Blindness or low vision affects approximately one in 100 Chinese older than 40 years. An estimated 4.1 million Chinese older than 40 years have low vision, and an estimated 1.6 million Chinese older than 40 years are blind.

Adult↗

PubMed2006

Prevalence of full-thickness macular holes in urban and rural adult Chinese: the Beijing Eye Study.

PURPOSE: To determine the prevalence of full-thickness macular holes in the elderly Chinese population. DESIGN: Population-based, cross-sectional cohort study. METHODS: The Beijing Eye Study included 4439 subjects out of 5324 subjects invited to participate (response rate 83.4%) aged 40 years or older. The present investigation consisted of 8653 (97.9%) eyes of 4346 subjects for whom readable fundus photographs were available. RESULTS: Full-thickness macular holes were found in eight (0.092%) eyes of seven (0.16%) patients (six women). Prevalence was 0.09 +/- 3.04% [95% confidence interval (CI): 0.03, 0.16%]. CONCLUSIONS: Full-thickness macular holes may be present in approximately 1.6 out of 1000 elderly Chinese in Northern China. Calculated for the entire population in China, the figure would be approximately 750,000 patients with unilateral full-thickness macular holes [n = 650,000 (95% CI: 217,000 to 1,156,000)] or bilateral full-thickness macular holes [n = 100,000 (95% CI: 33,000 to 178,000)].

Adult↗

PubMed2006

Prevalence and causes of visual field loss as determined by frequency doubling perimetry in urban and rural adult Chinese.

PURPOSE: To determine prevalence and causes of visual field loss (VFL) as determined by frequency doubling perimetry in elderly Chinese individuals. DESIGN: Population-based, cross-sectional cohort study. METHODS: The Beijing Eye Study included 4439 of 5324 subjects (83.4%) who were invited to participate with an age of 40+ years. Visual field was assessed by frequency doubling threshold perimetry. Main outcome measure was an abnormal visual field defined as at least one test location of reduced sensitivity. RESULTS: Of the 4439 people who were examined, 4350 subjects (98.0%; 8617 eyes) provided measurement data by frequency doubling perimetry. In subjects aged 40 to 49 years, the most frequent cause for VFL was degenerative myopia followed by glaucoma, other optic nerve diseases, and cataract. In the subjects aged 60 to 69 years, the most frequent cause for VFL was cataract, followed by glaucoma and degenerative myopia. In the subjects aged 70+ years, the most frequent cause for VFL was glaucoma, followed by cataract and degenerative myopia. VFL was associated significantly with age (P < .001), myopic refractive error (P < .001), rural region (P = .001), low level of education (P = .01), degree of nuclear cataract (P < .001), and intraocular pressure (P < .001). CONCLUSION: In contrast to Western countries, age-related macular degeneration and diabetic retinopathy play a minor role as a cause for VFL in China.

Adult↗

PubMed2006

Optic disk size in chronic glaucoma: the Beijing eye study.

PURPOSE: To evaluate whether eyes with chronic glaucoma have a larger or smaller optic disk than normal eyes. DESIGN: Population-based, cross-sectional cohort study. METHODS: The study included 4439 subjects out of 5324 subjects invited to participate with an age of 40+ years. Color optic disk photographs (45 degrees ) were morphometrically examined. RESULTS: After exclusion of aphakic eyes, pseudophakic eyes, and highly myopic eyes, data of 3989 subjects entered the statistical analysis. The mean optic disk area did not vary significantly (P > .05) between the nonglaucomatous group (2.61 +/- 0.50 mm(2)), eyes with glaucomatous appearance of the optic disk (2.69 +/- 0.63 mm(2)), eyes with glaucomatous optic disks and visual field defects (2.66 +/- 0.70 mm(2)), and eyes with elevated intraocular pressure (2.63 +/- 0.49 mm(2)). CONCLUSIONS: In adult Chinese, optic disk size may not markedly differ between normal eyes and eyes with chronic glaucoma.

Adult↗

PubMed2006

Frequency of optic disk hemorrhages in adult chinese in rural and urban china: the Beijing eye study.

PURPOSE: To determine the frequency of optic disk hemorrhages in the adult Chinese population. DESIGN: Population-based prevalence survey. METHODS: The study included 4439 subjects out of 5324 subjects invited to participate (response rate 83.4%) with an age of 40+ years. Mean age was 56.2 +/- 10.6 years. Color optic disk photographs (45 degrees) were morphometrically examined. RESULTS: Optic disk photographs were available for 8655 eyes of 4378/4439 (98.6%) subjects. Prevalence of disk hemorrhages was 107/8655 (1.24%; 95% confidence interval (CI): 1.00%, 1.47%) eyes. Occurrence of disk hemorrhages was significantly associated with glaucomatous optic nerve damage (P < .001; OR: 9.3; 95% CI: 5.6, 15.4) and age (P = .008; 95% CI: 1.01, 1.05). The occurrence of disk hemorrhages was not significantly associated with intraocular pressure (IOP) (P = .63; 95% CI: 0.97, 1.06), refractive error (P = .06; 5% CI: 0.87, 2.18), and visual field score (P = .81; 95% CI: 0.96, 1.03). Defining glaucoma as glaucomatous optic disk appearance, 20/107 (18.7%; 95% CI: 11.2%, 26.2%) disk hemorrhages were found in glaucomatous eyes. Out of 226 glaucomatous eyes, 20/226 (8.8%; 95%CI: 5.12%, 12.58%) eyes showed a disk hemorrhage. Hypertensive glaucoma eyes and normotensive glaucoma eyes did not vary considerably in frequency of disk hemorrhages (P = .44; OR: 1.82; 95% CI: 0.59, 5.68). CONCLUSIONS: Disk hemorrhages occur in a frequency of approximately 1.2% in adult Chinese. Major associated factors are glaucomatous optic neuropathy and age. Presence of a disk hemorrhage suggested glaucomatous optic nerve damage with a positive predictive value of approximately 20%. About 9% of glaucomatous eyes showed a disk hemorrhage at the time of examination.

Adult↗

PubMed2006

Retinal vascular abnormalities and prevalence of age-related macular degeneration in adult Chinese: the Beijing Eye Study.

PURPOSE: To evaluate whether retinal vessel abnormalities are associated with early or late age-related macular degeneration (AMD) in adult Chinese. DESIGN: Population-based prevalence study. METHODS: The Beijing Eye Study included 4439 (83.4%) subjects of 5324 living in a rural area or urban region of Greater Beijing, age older than 40+ years, and invited to participate. The participants underwent a detailed ophthalmic examination, including fundus photography. The photographs were graded using the Wisconsin Age-Related Maculopathy Grading system for evaluation of AMD, and using the Atherosclerosis Risk in Communities protocol for assessment of retinal vascular abnormalities. We examined focal and generalized arteriolar narrowing, arteriolar sheathing, and arteriovenous crossing abnormalities. RESULTS: Fundus photographs were available for 8655 eyes of 4376 (98.6%) subjects. Neither early nor late AMD was significantly (P > .15) associated with any of the retinal vascular abnormalities. CONCLUSIONS: Retinal vascular abnormalities are not markedly associated with the prevalence of early or late AMD.

Adult↗

PubMed2006

Prevalence and risk factors of lens opacities in urban and rural Chinese in Beijing.

OBJECTIVE: To determine the prevalence of lens opacities in the elderly Chinese population in an urban and a rural region of Beijing. DESIGN: Population-based cross-sectional study. PARTICIPANTS: The study included 4439 subjects of 5324 subjects invited to participate (response rate, 83.4%). The subjects were divided into a rural part (1973 subjects [44.4%]) and an urban part (2466 subjects [55.6%]). The study was limited to participants age 40 and older, and the mean age was 56.2+/-10.6 years (range, 40-101 years). METHODS: Nuclear, cortical, and posterior subcapsular lens opacities were assessed based on standardized slit-lamp photographs of the lens using a modification of the grading score of the Age-related Eye Disease Study (AREDS). MAIN OUTCOME MEASURES: Grading score of the AREDS. RESULTS: Lens data were provided for 4378 subjects (98.6%) of 4439 persons examined, which consisted of 8724 eyes. Prevalence of any cataract surgery was 1.3% (95% confidence interval [CI]: 1.0-1.7), which was statistically independent of gender (P = 0.51; odds ratio [OR]: 0.86; 95% CI: 1.00-1.34), rural area versus urban region (P = 0.25), and level of education (P = 0.84). Prevalence of any nuclear lens opacity was 82.0% (95% CI: 80.8-83.2); prevalence of any cortical lens opacity was 10.3% (95% CI: 9.4-11.3); and prevalence of any posterior subcapsular opacity was 4.3% (95% CI: 3.7-4.9). If grade 2 of nuclear lens opacity was considered to be normal, prevalence of nuclear cataract was 50.3% (95% CI: 48.8-51.8), and the overall prevalence of any cataract was 53.1% (95% CI: 51.6-54.6), increasing from 6.5% (95% CI: 5.2-7.8) in those subjects 40 to 49 years of age to 52.3% (95% CI: 47.4-55.3) in those who were 50 to 59 years of age, and to 97.8% (95% CI: 96.4-99.2) in those 70 years and older (P<0.001). Frequencies of any cortical cataract and any subcapsular posterior cataract were 10.3% (95% CI: 9.4-11.3) and 4.3% (95% CI: 3.7-4.9), respectively. CONCLUSIONS: Cataracts are common among adult Chinese residents in Beijing, with age as the most important associated factor. In view of the relatively low rate of cataract surgery performed so far, one may expect a marked increase in the number of cataract surgeries to meet the visual needs of the growing elderly population in China.

Adult↗

PubMed2006

Sonocatalytic damage of bovine serum albumin (BSA) in the presence of nanometer anatase titanium dioxide (TiO2).

The nanometer anatase titanium dioxide (TiO2) (a kind of crystal type of TiO2) powder was adopted as the sonocatalyst for the damage of bovine serum albumin (BSA) used as a model protein by low-power ultrasound (US) (80 kHz, 80 W). The effects of several factors on the damage of BSA molecule were reviewed by means of ultraviolet destruction and circular dichroism spectra. It was found that the BSA molecule underwent destruction of the secondary structure and loss of the alpha-helical configuration to a certain extent under ultrasonic irradiation in the presence of nanometer anatase TiO2 powder and that the damage caused by US integrated with TiO2 was more serious than those by only US or only TiO2. Furthermore, the damage degree was aggravated with the increase of TiO2, added to saturation, and then it was slowly weakened with the excessive TiO2. When a suitable amount of acid or base was added into the BSA solution, the sonocatalytic damage was also aggravated. Because the functions of proteins are decided by their space configurations, the changes of the configurations might cause the forfeiture of their function, even the apoptosis or necrosis of cells. Perhaps, an effective method of killing cancer cells by sonocatalytic damage of protein molecules in the presence of nanometer anatase TiO2 could be obtained from these experimental results.

Animals↗

PubMed2006

Polymorphisms in the two helicases ERCC2/XPD and ERCC3/XPB of the transcription factor IIH complex and risk of lung cancer: a case-control analysis in a Chinese population.

The transcription factor IIH (TFIIH) helicases ERCC2/XPD and ERCC3/XPB are responsible for opening the DNA strand around the lesion site during nucleotide excision repair process. Genetic variants in these two genes may be markers for interindividual variability in DNA repair capacity and thus predisposition to cancer risk. In this case-control study of 1,010 incident lung cancer cases and 1,011 age and sex frequency-matched cancer-free controls in a Chinese population, we genotyped eight tagging polymorphisms of ERCC2 and ERCC3 using the high-throughput Taqman platform to determine their associations with risk of lung cancer. Although none of the eight polymorphisms was individually associated with lung cancer risk, we found that genetic variants in ERCC2 and ERCC3 jointly contributed to lung cancer risk in a dose-response manner. Compared with those with 0 to 1 "at-risk" locus, subjects carrying >1 at-risk loci were at increased risk for lung cancer [adjusted odds ratio (OR), 1.29; 95% confidence interval (95% CI), 0.98-1.70 for 2 at-risk loci; adjusted OR, 1.38; 95% CI, 1.02-1.85 for 3 at-risk loci; and adjusted OR, 1.51; 95% CI, 1.09-2.10 for > or =4 at-risk loci, respectively; P(trend) = 0.015]. This combined effect was slightly more evident in young subjects (<60 years), males, current smokers, and those with family history of cancer, particularly for histologic type of adenocarcinomas. No evidence for interaction was found. These findings indicate that these tagSNPs of the ERCC2 and ERCC3 along with their surrounding regions may serve as biomarkers of susceptibility to lung cancer, which warrant further validation by other population-based and phenotypic studies to determine the biological relevance of these tagSNPs.

Adenocarcinoma↗

PubMed2006

Visual response properties of retinal ganglion cells in the royal college of surgeons dystrophic rat.

PURPOSE: Alterations in retinal ganglion cell response patterns were profiled in dystrophic Royal College of Surgeons (hereafter RCS) rats over the first 100 postnatal days as a baseline for retinal rescue and vision restoration strategies. This method enabled the evaluation of the extent to which postreceptoral neuronal attributes in degenerating retinas mirror inferred declines in photoreceptor function. METHODS: Single-unit responses from large retinal ganglion cells were recorded from age-matched dystrophic RCS (RCS-rdy(-)) and congenic RCS-p(+) (hereafter wild-type or wt) rats were recorded in vitro under visual control. Cells were profiled with conventional spatial and flux stimulus modulations. RESULTS: Ganglion cell single unit and population attributes alter slowly over the course of photoreceptor degeneration in dystrophic RCS rats, with significant decreases in apparent receptive field size, contrast sensitivity, and threshold sensitivity detected by the first month of life. Spatial frequency tuning and contrast responses were extremely weak by postnatal day (P)76, paralleled by a progressive decline in signal-to-noise (S-N) ratio to roughly unity by postnatal day (P)107. This decline was only a simple loss of responsivity, as background firing rates increased substantially over time. Whereas wt retinas were dominated by ON-center cells (15/23 cells), dystrophic animals were dominated by OFF-center cells by P47 (24/27 cells). CONCLUSIONS: The first definitive signs of degeneration in dystrophic RCS rats are parallel decreases in ganglion cell threshold sensitivity and receptive field size, followed by deterioration in spatial summation. Arguably, these changes can be qualitatively explained as photoreceptor signaling losses. However, the apparent shift in population profile from ON- to OFF-center ganglion cells long before loss of the b-wave at P90 implies that a reactive mechanism such as bipolar cell rewiring and/or transformation of neuronal phenotypes occur during the early phase of photoreceptor stress, before rod and cone death.

Animals↗

PubMed2006

Simultaneous determination of protocatechuic acid, syringin, chlorogenic acid, caffeic acid, liriodendrin and isofraxidin in Acanthopanax senticosus Harms by HPLC-DAD.

A high performance liquid chromatography (HPLC) method was developed for the first time to quantify simultaneously the six major active ingredients in Acanthopanax senticosus (Rupr. et Maxim.) Harms, namely protocatechuic acid, syringin, chlorogenic acid, caffeic acid, liriodendrin and isofraxidin. The analysis was performed by a reverse phase gradient elution with an aqueous mobile phase (containing 0.05% phosphoric acid) modified by acetonitrile and diode-array multiple-wavelength UV detector (DAD). Six regression equations showed good linear relationships between the peak area of each marker and concentration. The recoveries of the markers listed above were 92.3%, 93.9%, 90.3%, 93.1%, 94.3% and 90.7%, respectively. The relative standard deviation of intra-day and inter-day were less than 2.7% and 3.1%, respectively. This method was validated for specificity, accuracy, precision and limits of quantification. Medicinal materials of ten commercial brands were analyzed and found to contain different amounts of the six bioactive markers. The method developed can be used for the quality control of Acanthopanax senticosus (Rupr. et Maxim.) Harms.

Caffeic Acids↗

PubMed2006

[Three essential elements of glaucomatous optic nerve damage and discrimination of optic nerve rim loss].

Three essential elements of glaucomatous optic nerve damages are optic nerve rim loss, retinal nerve fiber layer defects (RNFLD) and optic disc linear hemorrhages. It's suggested that if there are two positive signs detected among the three elements, the diagnosis of the glaucomatous optic nerve damages can be established. There is no definitely described how to identify optic nerve rim loss in the previous textbooks, therefore it is important to know about the morphological features of the physical optic nerve rim and influence factors before discrimination of optic nerve rim loss. Most of physical optic nerve rim are in accordance with ISNT rule, physical large optic cups are also accord with ISNT rule. Exceptional cases exist in two patterns, optic nerve rim loss or normal optic nerve rim morphological variances. The latter includes part of small discs, horizontally oval optic discs, the position of the central retinal vessel trunk and the titled optic discs which affect the morphological feature of optic nerve rim as well. In some small discs, the width of inferior rim is narrower than that of superior rim, therefore, the inferior or the superior rim loss can be evaluated by comparison with nasal rim width. Concerning horizontal oval optic discs, the width of inferior rim and superior rim should be compared to evaluate whether there is the optic nerve rim loss. If those patterns of normal optic nerve rim variances can be recognized, it is not difficult to find the presence of the optic nerve rim loss. However, not all of the optic nerve rim loss is due to glaucomatous optic nerve damages, non-glaucomatous optic nerve damage should be distinguished.

Diagnosis, Differential↗

PubMed2006

[Passive FTIR remote sensing of gaseous pollutant in heated plume].

The principle and techniques of passive remote sensing of gaseous pollutant in heated plume was illustrated and discussed in this paper. The algorithm of radiance spectra and transmittance spectra in measured region was proposed, and the method of retrieving gas concentrations with NLLS fitting algorithm was also proposed. The remote senseing of actual gaseous pollutant of smokestack was done, and the quantitative analysis of SO2 and CO2 was completed.

English Abstract↗

PubMed2006

[Error analysis and calibration method of complex spectrum of Fourier transform infrared spectrometer].

The phase shift in complex spectrum of Fourier transform infrared (FTIR) spectrometer was discussed. A rigorous derivation showed the relation between the phase shift and complex spectrum. The reason for the radiation offset in FTIR measurement was analysed. The present article presents a calibration method of FTIR complex spectrum, which can adjust the radiation offset. The comparison between experiment data and theoretical computation showed that the method is precise.

English Abstract↗

PubMed2006

[Identification study of Mongolian herbal medicine Rubus Sachalinesis Leveille and its forgeries by UV/fluorescence/IR spectroscopy].

Identification study of four species of Mongolian herbal medicine by UV/fluorescence/IR spectroscopy was carried out. Ultrasonic extracts of Mongolian herbal medicine Rubus Sachalinesis Leveille and its substitute materials Sambucus williamsii Hance and Uncaria rhynchophylla (Miq.) Jacks., and its false medicine Cinnamomum cassia Presl by methyl alcohol, petroleum ether and chloroform were obtained respectively, UV/fluorescence spectral scans for the above herbal medicines were taken and the spectra obtained were compared. Besides, the IR spectra obtained from the herbal medicines were compared. It was shown that the absorption peaks of UV spectra of the four species of Mongolian herbal medicine differ from each other when the methyl alcohol, petroleum ether and chloroform were used as extracting solvent, while there is a selectivity for the solvent when fluorescence spectrum was used to differentiate those medicines. Only when the methyl alcohol was used as extracting solvent, there are clear differences among the IR spectra of the four species of medicine. Therefore, three kinds of spectra are available in identifying the four species of herbal medicine. Among them, IR spectroscopy is noted for its more information about the fingerprints of herbal medicines, and being direct and simple, which is one of the methods worth recommending for identifying Mongolian herbal medicine.

China↗