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Biomedical subjects

L Xu

Publications and source records attributed to L Xu.

853 records · Page 48Linked to original sources
PubMedDate not supplied

Prevalence of retinitis pigmentosa in urban and rural adult Chinese: The Beijing Eye Study.

PURPOSE: To determine the prevalence of retinitis pigmentosa in the elderly Chinese population. METHODS: The Beijing Eye Study is a population-based, cross-sectional cohort study and included 4439 subjects out of 5324 subjects invited to participate (response rate 83.4%) with an age of 40+ years. Readable fundus photographs were available for 4027 (90.7%) subjects. Diagnostic criteria for retinitis pigmentosa were visual field defects on frequency doubling perimetry, typical ophthalmoscopic abnormalities such as retinal pigment deposits, retinal arteriole attenuation, and pigment epithelial atrophy, and no other reason for perimetric defects and fundus abnormalities. RESULTS: Retinitis pigmentosa was diagnosed in four subjects (all men). Its prevalence was 0.099+/-3.15% (95% CI: 0.00, 0.2). CONCLUSIONS: Retinitis pigmentosa with typical fundus appearance and functional loss may be present in about 1 out of 1000 elderly Chinese in Northern China. Calculated for the whole population in China, the figure would be 1.3 million patients with retinitis pigmentosa.

Adult↗
PubMedDate not supplied

Repeatability of distortion product otoacoustic emissions in normally hearing humans.

Distortion product otoacoustic emissions (DPOAEs) at the frequency of 2f1-f2 were measured in one or both ears of 12 young adults during 4 test sessions over a 6-week period. The purpose was to determine the variability in DPOAE amplitudes and 'detection thresholds' over repeated measurements using a computer-based time-averaging system. DPOAEs were generated with f1 and f2 relative to (f1f2)1/2 in two basic paradigms: (a) fixed levels of L1 = L2 of 70 and 55 dB SPL over a stimulus range from 0.8 to 8 kHz in 0.2-octave intervals; (b) input-output functions in stimulus regions of 0.8, 1, 1.5, 2, 3, 4 and 6 kHz, L1 from 35 to 70 dB SPL changing in 5-dB steps and L2 at 6 dB below the amplitude of L1. The mean variability of DPOAE amplitudes with equilevel stimuli was 1.8 dB (SD = 1.8) for L1 = 70 dB SPL and 2.9 dB (SD = 2.7) for L1 = 55 dB SPL. It was 1.7 dB (SD = 1.7) and 2.4 dB (SD = 2.0) for comparable levels of L1 with L2 at 6 dB below L1. Variability in amplitude of the DPOAEs for the fixed-level condition was greatest overall above 6 kHz and below 1 kHz and in the 2-kHz region for one third of the subjects. Neither individual differences in emission amplitudes nor the presence of spontaneous otoacoustic emissions had a significant influence on the amount of amplitude variability within ears. Variability was not influenced by the length of time between measurements from 1 to 6 weeks.(ABSTRACT TRUNCATED AT 250 WORDS)

Acoustic Stimulation↗
PubMedDate not supplied

Treatment of acute promyelocytic leukemia with arsenic trioxide: clinical and basic studies.

Arsenic trioxide (As2O3) has recently been identified as an effective drug in the treatment of newly diagnosed and relapsed acute promyelocytic leukemia (APL) without cross-resistance to all-trans retinoic acid and achieved complete remission rates of 80-90% according to most reports. With intravenous infusion at a dose of 0.08-0.16 mg/kg daily, a course of 28-42 days is required to induce remission. As2O3 in combination with chemotherapy as postremission therapy results in longer survival than arsenic alone. In vitro, As2O3 exerts dose-dependent dual effect; triggering apoptosis at relatively high concentration (0.5-2.0 micromol/l), which is associated with the disruption of mitochondrial transmembrane potentials, while inducing partial differentiation at low concentration (0.1-0.5 micromol/l), which might be related to retinoic acid signaling pathway. Importantly, at both concentrations, As2O3 can degrade PML (promyelocytic leukemia) -RAR alpha (retinoic acid receptor), an oncoprotein that has a central role in leukemogenesis.

Apoptosis↗
PubMedDate not supplied

Sequence determination of low molecular weight salivary histidine-rich polypeptides from electroblots.

Saliva contains six major cationic antifungal histidine-rich polypeptides (HRP) which are degraded by salivary proteases to smaller minor peptides. The primary structures of the minor peptides from one of these major HRPs, HRP-5, were elucidated in this study. Digestion of the HRP-5 substrate by human parotid saliva was followed by cationic polyacrylamide gel electrophoresis, electroblotting onto Whatman GF/C paper and gas-phase sequencing of Coomassie blue stained blots. A total of eight minor peptides were structurally analyzed. The smallest molecule characterized contained seven amino acid residues, suggesting that the technique was applicable for sequence determination of cationic peptides in the low molecular weight range.

Amino Acid Sequence↗
PubMedDate not supplied

Analysis of a new PM motor design for a rotary dynamic blood Pump.

The permanent magnet (PM) motor for a rotary dynamic blood pump requires high power density to coordinate the motor size with the limited pump space and high efficiency to reduce the size and weight of the associated batteries. The motor also serves as a passive axial magnetic thrust bearing, a reacting hydraulic force, and provides a stabilizing force for the radial journal bearing. This article presents analysis of a new PM motor for the blood pump application. High power density is achieved by using the Halbach magnetic array, and high efficiency is accomplished by optimizing the rotor magnet assembly and the stator slots/windings. While both radial and axial forces are greatly enhanced, pulsating components of the torque and force are also significantly reduced.

Biomechanical Phenomena↗
PubMedDate not supplied

Design of a DSP controller for an innovative ventricular assist system.

The design and development of the digital signal processor controller for an innovative ventricular assist system is presented. A DSP56005 is used as the central processor, with other peripheral components. System hardware and software were developed through the advanced development system, and stand alone operation of the system was also accomplished. Two different control modes--current control mode and speed control mode--were developed and investigated. Performance of efficiency and dynamic response were examined through experimental testing.

Biomedical Engineering↗