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J B Liu

Publications and source records attributed to J B Liu.

At least 19 recordsLinked to original sources
PubMed2004

Observation of a threshold enhancement in the plambda invariant-mass spectrum.

An enhancement near the m(p)+M(Lambda) mass threshold is observed in the combined pLambda and pLambda invariant-mass spectrum from J/psi-->pK(-)Lambda;+c.c. decays. It can be fit with an S-wave Breit-Wigner resonance with a mass m=2075+/-12(stat)+/-5(syst) MeV and a width of Gamma=90+/-35(stat)+/-9(syst) MeV; it can also be fit with a P-wave Breit-Wigner resonance. Evidence for a similar enhancement is also observed in psi(')-->pK(-)Lambda;+c.c. decays. The analysis is based on samples of 5.8x10(7)J/psi and 1.4x10(7)psi(') decays accumulated in the BES II detector at the Beijing Electron-Positron Collider.

Journal Article↗
PubMed2004

Observation of the decay psi(2S)-->K0SK0L.

The decay psi(2S)-->K(0)(S)K(0)(L) is observed using psi(2S) data collected with the Beijing Spectrometer at the Beijing Electron-Positron Collider; the branching fraction is determined to be B(psi(2S)-->K(0)(S)K(0)(L))=(5.24+/-0.47+/-0.48)x10(-5). Compared with J/psi-->K(0)(S)K(0)(L), the psi(2S) branching fraction is enhanced relative to the prediction of the perturbative QCD "12%" rule. The result, together with the branching fractions of psi(2S) decays to other pseudoscalar meson pairs (pi(+)pi(-) and K+K-), is used to investigate the relative phase between the three-gluon and the one-photon annihilation amplitudes of psi(2S) decays.

Journal Article↗
PubMed2004

Assessment of angiogenesis: implications for ultrasound imaging.

In this paper, the fundamentals of tumor angiogenesis and the implications for ultrasound imaging will be described. Twenty-eight athymic nude mice were implanted with the human melanoma cell lines DB-1 or MW-9 (14 mice/group). Ultrasound contrast agents were injected in the tail veins. Power Doppler and pulse inversion harmonic imaging (PI-HI) was performed (in real time and intermittently). Ultrasound results were compared to immunohistochemical stains for endothelial cells (CD31), vascular endothelial growth factor (VEGF), and cyclooxygenase-2 (COX-2). Linear regression analysis indicated statistically significant correlations between percent area stained with COX-2 and with VEGF relative to power Doppler (p<0.05) and intermittent PI-HI (p<0.05) measures of tumor neovascularity in the MW-9 and the DB-1 mice, respectively. Preliminary results from a human trial of the anti-angiogenic drug Angiostatin (Entremed, Rockville, MD) showed tumor volumes increased in two patients, while the vascularity remained virtually unchanged. Conversely, in three patients with diminished tumor volumes vascularity increased by 38%. In conclusion, contrast enhanced ultrasound imaging of tumor neovascularity may provide noninvasive markers of angiogenesis and may become a useful tool for monitoring anti-angiogenic therapies in vivo.

Angiogenesis Inhibitors↗
PubMed2004

Acoustic microscopy system: design and preliminary results.

An acoustic microscopy system was designed to perform 2D imaging in the C-plane with a single-element transducer. The ultrasound transducer was fabricated by polishing bulk lithium niobate (LiNbO(3)) to the required thickness (approximately 60 or 45 micro) for the desired operating frequency (55 or 75 MHz). The polished LiNbO(3) was attached to acoustic backing and matching layers. Finally, an epoxy lens was applied and the transducer mounted in a housing. The transducer was mounted in a 3D motorized positioning stage and operated by a high-frequency pulser/receiver. Received echoes were sampled with a 2 GHz ADC card and displayed on a PC using software developed in the Matlab environment. Transducer frequency and bandwidth were measured off a steel plate positioned at the focal length. A penny was scanned initially to confirm expected performance before acquiring data from liver (n=3) and spleen (n=3) specimens. For the first probe, the peak frequency was 54.05 MHz with a -6 dB bandwidth of 6.76 MHz. The axial and lateral resolutions were estimated to be 114 and 188 microm, respectively. For the second probe, the peak frequency was measured to 82 MHz with a -6 dB bandwidth of approximately 23 MHz. The axial and lateral resolutions were estimated to be around 33 and 81 microm, respectively. C-scans of the penny clearly showed detailed structures on front and back, while the capsule and the trabecular structures of the splenic tissues could easily be separated in different layers. In conclusion, an acoustic microscopy system operating at 55-75 MHz has been constructed and the feasibility of obtaining high-resolution images of tissue specimens demonstrated.

Acoustics↗
PubMed2004

The genetic epidemiology of alopecia areata in China.

BACKGROUND: Alopecia areata (AA) is hypothesized to be an organ-specific autoimmune disease with genetic predisposition and an environmental trigger. There are few clinical data in Asians. OBJECTIVES: To describe the genetic epidemiological features of AA patients in China and to determine the possible genetic model for AA. METHODS: Data for 1032 patients with AA were obtained by questionnaire in the Institute of Dermatology of Anhui Medical University in China from 2001 to 2003. Complex segregation analysis and heritability analysis were performed using Falconer's method, EPI INFO 6.0 and SAGE-REGTL programs. RESULTS: In total, 1032 AA patients (male/female ratio 1.1 : 1) were enrolled, representing 0.94% of the total number of cases seen in our outpatient clinic during that time. The mean +/- SD age of onset was 28.98 +/- 13.43 years. The difference between the mean age of onset in males and females was not significant. Most patients (82.6%) experienced their first episode of AA within the first four decades of life. A positive family history of AA was obtained in 87 patients (8.4%). The prevalence of AA in first-, second- and third-degree relatives of the proband with AA was 1.6%, 0.19% and 0.03%, respectively. These figures were higher than those in controls. A greater severity and longer duration of AA were seen in the early onset group than in the late-onset group. The early onset group also had more affected first- and second-degree relatives. The heritability of AA in first-, second- and third-degree relatives was 47.16%, 42.53% and 22.29%, respectively. Based on the REGTL results, the best model was a polygenic additive model for AA. CONCLUSIONS: The effect of genetic factors is strong in AA, but environmental factors such as infection and psychological stress may still play an important role. Our findings on the genetics of AA are consistent with a polygenic additive mode of inheritance.

Adolescent↗
PubMed2004

A novel mutation of the DSRAD gene in a Chinese family with dyschromatosis symmetrica hereditaria.

Dyschromatosis symmetrica hereditaria (DSH) is a pigmentary genodermatosis of autosomal dominant inheritance characterized by a mixture of hyperpigmented and hypopigmented macules distributed on the dorsal aspects of the hands and feet. It is caused by mutations of the RNA-specific adenosine deaminase gene. We report the identification of a Chinese family with a three-generation pedigree of DSH, in whom a novel tyrosine substitution mutation in DSRAD was demonstrated: a heterozygous nucleotide A-->G transition at position 2879 in exon 10 of the DSRAD gene was detected.

Adenosine Deaminase↗
PubMed2003

Observation of a near-threshold enhancement in the pp mass spectrum from radiative J/psi-->gammapp decays.

We observe a narrow enhancement near 2m(p) in the invariant mass spectrum of pp pairs from radiative J/psi-->gammapp decays. No similar structure is seen in J/psi-->pi(0)pp decays. The results are based on an analysis of a 58 x 10(6) event sample of J/psi decays accumulated with the BESII detector at the Beijing electron-positron collider. The enhancement can be fit with either an S- or P-wave Breit-Wigner resonance function. In the case of the S-wave fit, the peak mass is below 2m(p) at M=1859(+3)(-10) (stat)+5-25(syst) MeV/c(2) and the total width is Gamma<30 MeV/c(2) at the 90% confidence level. These mass and width values are not consistent with the properties of any known particle.

Journal Article↗
PubMed2002

Contrast enhanced vascular three-dimensional ultrasound imaging.

In other imaging modalities three-dimensional (3D) data displays are well established; not so in ultrasound. Due to the real-time requirements of ultrasound the time available to compute 3D displays is limited, particularly when flow data is acquired with Doppler techniques. Consequently, it is only recently that improvements in computer processing power have resulted in useful vascular 3D ultrasound scans. Many manufacturers have now implemented free-hand 3D power Doppler capabilities on their scanners. However, to obtain flow signals from smaller vessels associated e.g., with tumor neovascularity, may very well require the introduction of a microbubble based ultrasound contrast agent into the blood stream. Given the up to 30 dB enhancement of Doppler signals produced by the contrast microbubbles quite spectacular vascular 3D images are feasible. Moreover, new contrast imaging techniques, such as harmonic imaging, have now permitted 3D vascular information to be acquired and displayed in grayscale with the associated improvement in resolution. In this paper we will review different aspects of contrast enhanced vascular 3D ultrasound imaging including implementation, contrast specific techniques and in vivo imaging.

Animals↗
PubMed2001

[Evaluation of clinical therapeutic efficacy by injecting adriamycin to the nerve in primary trigeminal neuralgia].

Sixty-eight cases suffering from primary trigeminal neuralgia were performed by injecting adriamycin to the nerve. The results show that the symptoms of trigeminal neuralgia completely disappeared in all the cases during two weeks after the operation in which 63.2% in 24 hours, 28.9% in one week and 7.9% in two weeks. the recurrence rate in three years was 10.3% and in three to five years was 15.4%. This technique has the features of low recurrence rate, steady therapeutic effect, safety and microtrauma.

Adult↗
PubMed2001

Contrast-enhanced power Doppler imaging of normal and decreased blood flow in canine prostates.

The purpose of this study was to investigate if Sonazoid, a new ultrasound (US) contrast agent, can improve the delineation of areas with normal and decreased blood flow in the prostate. Sonazoid was administered in the dose range of 0.00625-0.0375 microL microbubbles/kg into five anaesthetised mongrel adult male dogs. Transrectal power Doppler imaging of the prostate was performed in 2-D and 3-D with a C9-5 end-fire probe, using an HDI 3000 scanner. An area of decreased blood flow was created by inducing tissue ablation with a CL60 laser system, to mimic an avascular lesion. A subjective assessment of the intraprostatic vessels and the prostate vascular architecture was performed, with and without Sonazoid, before and after inducing the abnormal site. Visibility of the prostate blood flow improved following Sonazoid injection (p < 0.001). A symmetric, radial vascular pattern was identified in the normal prostate prior to tissue ablation, but only on the enhanced images. After tissue ablation, a disturbance of the normal vascular pattern and identification of areas with lack of blood flow was possible, following Sonazoid injection. Furthermore, the location and size of these areas were verified in all dogs by gross histology examination. Sonazoid enhances the visibility of the prostate vascular architecture and improves, thereby the delineation of areas with normal and decreased blood flow.

Animals↗
PubMed2001

Experience with endoluminal ultrasonography in the urinary tract.

Ultrasonography has been an invaluable tool in the field of urology for its noninvasiveness, safety, and relatively low cost. However, examination of the ureter with ultrasound is difficult because of the distance of the transducer from the ureter and because of intervening structures such as nonconductive bowel gas. As smaller probes have become available, attempts have been made to apply them to endoluminal use. Endoluminal ultrasonography has been employed in urology to examine the proper placement of injected collagen, diagnose urethral diverticula, diagnose and stage upper tract transitional-cell carcinoma, locate crossing vessels to guide endopyelotomy, diagnose submucosal calculi, and examine the severity and length of ureteral strictures.

Collagen↗
PubMed2001

Local longitudinal muscle shortening of the human esophagus from high-frequency ultrasonography.

We analyzed local longitudinal shortening by combining concurrent ultrasonography and manometry with basic principles of mechanics. We applied the law of mass conservation to quantify local axial shortening of the esophageal wall from ultrasonically measured cross-sectional area concurrently with measured intraluminal pressure, from which correlations between local contraction of longitudinal and circular muscle are inferred. Two clear phases of local longitudinal shortening were observed during bolus transport. During luminal filling by bolus fluid, the muscle layer distends and the muscle thickness decreases in the absence of circular or longitudinal muscle contraction. This is followed by local contraction, first in longitudinal muscle, then in circular muscle. Maximal longitudinal shortening occurs nearly coincidently with peak intraluminal pressure. Longitudinal muscle contraction begins before and ends after circular muscle contraction. Larger longitudinal shortening is correlated with higher pressure amplitude, suggesting that circumferential contractile forces are enhanced by longitudinal muscle shortening. We conclude that a peristaltic wave of longitudinal muscle contraction envelops the wave of circular muscle contraction as it passes through the middle esophagus, with peak longitudinal contraction aligned with peak circular muscular contraction. Our results suggest that the coordination of the two waves may be a physiological response to the mechanical influence of longitudinal shortening, which increases contractile force while reducing average muscle fiber tension by increasing circular muscle fiber density locally near the bolus tail.

Deglutition↗
PubMed2001

Blood flow estimation with harmonic Flash Echo Imaging.

Blood volume flow estimation remains an important task for the functional evaluation of internal organs. In vitro and in vivo flow estimation has been carried out using Flash Echo Imaging in harmonic mode after the administration of microbubble-based ultrasound contrast agents. The in vitro flow volume rate correlated with the constant replenishment level but less so with the video intensity decay rate. The in vivo volume flow rates obtained in four dogs agreed well with CVI-Q (time domain correlation) based flow measurement. Our experimental results indicate that the volume flow rate can be accurately estimated in vitro and in vivo using harmonic Flash Echo imaging.

Animals↗
PubMed2001

The role of contrast-enhanced sonography for radiofrequency ablation of liver tumors.

OBJECTIVE: To assess the feasibility and usefulness of contrast-enhanced sonography for tumor detection and guidance of liver VX2 tumor ablation and to evaluate post radiofrequency ablation effectiveness. METHODS: VX2 tumors were implanted into the livers of 6 rabbits. Both conventional and harmonic gray scale and power Doppler imaging were performed with a commercially available scanner to evaluate the liver tumors before and after intravenous injection of a sonographic contrast agent before and after radiofrequency ablation. Contrast-enhanced imaging was used to detect the tumors before ablation, to guide needle insertion, and to measure the ablation sites after radiofrequency ablation. Pathologic examination was performed for comparison. RESULTS: Three tumors were seen without contrast enhancement, whereas 10 tumors (<1 cm) were detected with contrast enhancement. Intentionally, 2 tumors were completely ablated and 5 tumors were partially ablated. In 3 cases, incompletely ablated tumors could only be identified on contrast-enhanced Doppler imaging by enhancing the detection of residual tumor vascularity. There was excellent concordance between sonographic imaging and gross pathologic findings. CONCLUSIONS: Contrast-enhanced sonographic imaging appears useful for detection of liver tumors and for guiding and monitoring tumor ablation therapies.

Animals↗
PubMed2001

[PACS-based endoscope image acquisition workstation].

A practical PACS-based Endoscope Image Acquisition Workstation is here introduced. By a Multimedia Video Card, the endoscope video is digitized and captured dynamically or statically into computer. This workstation realizes a variety of functions such as the endoscope video's acquisition and display, as well as the editing, processing, managing, storage, printing, communication of related information. Together with other medical image workstation, it can make up the image sources of PACS for hospitals. In addition, it can also act as an independent endoscopy diagnostic system.

Computer Communication Networks↗
PubMed2000

Comparison of fundamental and wideband harmonic contrast imaging of liver tumors.

Wideband harmonic imaging (with phase inversion for improved tissue suppression) was compared to fundamental imaging in vivo. Four woodchucks with naturally occurring liver tumors were injected with Imagent (Alliance Pharmaceutical Corp., San Diego, CA). Randomized combinations of dose (0.05, 0.2 and 0.4 ml/kg) and acoustic output power (AO; 5, 25 and 63% or MI < or = 0.9) were imaged in gray scale using a Sonoline Elegra scanner (Siemens Medical Systems, Issaquah, WA). Tumor vascularity, conspicuity and contrast enhancement were rated by three independent observers. Imagent produced marked tumor enhancement and improved depiction of neovascularity at all dosages and AO settings in both modes. Tumor vascularity and enhancement correlated with mode, dose and AO (P < 0.002). Fundamental imaging produced more enhancement (P < 0.05), but tumor vascularity and conspicuity were best appreciated in harmonic mode (P < 0.05). Under the conditions studied here, the best approach was wideband harmonic imaging with 0.2 ml/kg of Imagent at an AO of 25%.

Analysis of Variance↗
PubMed2000

Three-dimensional esophageal varix model quantification of variceal volume by high-resolution endoluminal US.

BACKGROUND: The purpose of this study was to evaluate the accuracy and reproducibility of three-dimensional volume measurements by high-resolution endoluminal ultrasound in an esophageal varix model. METHODS: An esophageal varix model was made by filling three esophageal dilatation catheters with various volumes of water. A 20 MHz ultrasonography transducer was then pulled along the length of the catheters at a constant rate (1.25 mm/sec) while videotaping the procedure. Cross-sectional surface area measurements of each catheter were taken every second and the cross-sectional surface area was multiplied by the length of each catheter, as determined by high-resolution endoluminal ultrasound, to determine the volume in each catheter. Interobserver variability was calculated, and three-dimensional reconstruction was performed. RESULTS: The measured volumes corresponded closely with the actual volumes with an error ranging from 0% to 15.4%. The correlation between actual and measured volumes was r = 0.988. The interobserver variability ranged from r = 0.951 to r = 0.994. Actual esophageal varices were then imaged in a similar fashion to determine the feasibility of this method in patients with esophageal varices. CONCLUSIONS: High-resolution endoluminal ultrasound is an accurate and reproducible method of measuring volumes in an esophageal varix model and can be used in a clinical setting to determine variceal volume. Volume studies are now underway in human subjects.

Endosonography↗