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Biomedical subjects

P Xue

Publications and source records attributed to P Xue.

At least 19 recordsLinked to original sources
PubMed2006

Short-term administration of ACTH improves plasma lipid profile and renal function in kidney transplant patients.

The present study investigated effects of short-term administration of adrenocorticotrophic hormone (ACTH) on blood lipid profile and renal function in kidney transplant patients. Six patients who had kidney transplantations 2 to 10 years earlier received ACTH intramuscularly (1 mg/d) for 4 days. We analyzed serum levels of lipids, lipoproteins, apolipoproteins, blood creatinine, and other parameters. Short-term ACTH treatment significantly decreased serum apolipoprotein B and apolipoprotein AI, whereas it significantly increased plasma high-density lipoproteins (HDL). Interestingly, creatinine level moderately decreased and creatinine clearances moderately increased among five of six patients. Hepatic function and serum concentration of cyclosporine did not change. There were no serious side effects during ACTH treatment. It was concluded that ACTH treatment had beneficial effects on serum lipoprotein profile, potentially improving renal function in kidney transplant patients. Further observations are needed to confirm these effects.

Adrenocorticotropic Hormone↗
PubMed2004

Management of pediatric radiation dose using GE's Revolution digital radiography systems.

Digital flat-panel x-ray detectors offer excellent image quality and dose efficiency in addition to clinical productivity, connectivity, and adaptability to advanced clinical applications. GE's Revolution systems provide two modes of exposure control for setting the dose operating point, fixed time and automatic exposure control, the latter of which maintains high image signal-to-noise ratio for the given technique settings. In addition to enhancing detail contrast and compressing the dynamic range, postprocessing automatically determines the best window level and width for display, taking into account the dose at which the image was acquired. Several studies have examined the reduction in patient dose achievable with Revolution systems as compared to competing technologies, and results indicate significant dose savings with equivalent or superior image quality. For pediatric exams, pediatric default techniques provide for a lower patient dose as compared to adult techniques. Therefore, GE's Revolution systems can achieve a high image quality-to-dose ratio for pediatric imaging using the combined advantages of dose-efficient detection, advanced postprocessing, and independently adjustable pediatric techniques.

Child↗
PubMed2001

[Influence of a triplex superimposed treatment on HBV replication and mutation during treating chronic hepatitis B].

OBJECTIVE: To observe and evaluate the influence of a new antiviral treatment scheme on HBV replication and mutation during treating chronic hepatitis B. METHODS: In the test group, lamivudine, IFN alpha-2b, Astragalus membranaceus were chosen as a triplex superimposed treatment scheme for treating the patients who were on the state of HBV high replication and involved in the clinical condition of chronic hepatitis B. The control group was treated with lamivudine alone. The observed parameters percentage of patients in whom HBV DNA became undetectable (serum HBV DNA<1.6 ng/L), HBeAg/anti-HBe seroconversion rate; HBV DNA serum level; HBV YMDD mutation rate and pre-C region mutation rate. RESULTS: Compared with that of the control group, HBV DNA undetectable rate of the test group increased markedly at weeks 12, 36, 48(P <0.05), HBeAg negative rate of the group increased markedly at week 36, 48(P <0.05), while anti-HBe positive rate increased only at week 48 (31.58 vs.19.23%, P <0.05). After 4 weeks of treatment, HBV DNA serum level of both the test group and the control group reduced very remarkably (P <0.01), and at week 48, reduced more significantly (P <0.001). Compared with the control group, HBV DNA serum level of the test group reduced notably at week 12 (P <0.05) and very notable at week 36 and 48(P <0.01). At week 12, the pre-C region mutation occurred in the test group, and at week 24, 36,48, the pre-C region and YMDD mutations occurred in both the test group and the control group. CONCLUSIONS: As to anti-viral treatment of chronic hepatitis B, the triplex superimposed treatment had better efficacy than lamivudine alone.

Adolescent↗
PubMed2000

Study of the electrochemical behavior of mitoxantrone and its determination at a Co-C modified ultramicroelectrode.

In 0.005 mol dm-3 Tris-0.05 mol dm-3 NaCl buffer solution (pH 7.10), the electrochemical behavior of mitoxantrone was studied by linear-sweep voltammetry and cyclic voltammetry at a Co-carbon fiber ion implantation modified ultramicroelectrode. A sensitive reduction peak was obtained. The peak potential was -0.798 V (vs. SCE), the peak current was proportional to the concentration of mitoxantrone over the range of 2.0 x 10(-7)-6.0 x 10(6) mol dm-3 and the detection limit was 4.2 x 10(-8) mol dm-3. This method was applied to the direct determination of mitoxantrone in urine. Recoveries were in the range 95.4-105.8%. The reduction process was quasi-reversible with absorptive characteristics at a Co-C ultramicroelectrode. According to Laviron's theory, the electrode reaction rate constant ks and the electron transfer alpha of mitoxantrone were 4.4 s-1 and 0.48, respectively. The composition and depth distribution of elements on the surface of the Co-C ultramicroelectrode were determined by Auger electron spectroscopy. The experiments showed that Co was implanted into the surface of the carbon fiber, and the Co-C ultramicroelectrode had good stability and reproducibility.

Journal Article↗
PubMed2000

Dose efficiency and low-contrast detectability of an amorphous silicon x-ray detector for digital radiography.

The effect of dose reduction on low-contrast detectability is investigated theoretically and experimentally for a production grade amorphous silicon (a-Si) x-ray detector and compared with a standard thoracic screen-film combination. A non-prewhitening matched filter observer model modified to include a spatial response function and internal noise for the human visual system (HVS) is used to calculate a signal-to-noise ratio (SNR) related to object detectability. Other inputs to the SNR calculation are the detective quantum efficiency (DQE) and the modulation transfer function (MTF) of the imaging system. Besides threshold detectability, the model predicts the equivalent perception dose ratio (EPDR), which is the fraction of the screen film exposure for which the digital detector provides equal detectability. Images of a contrast-detail phantom are obtained with the digital detector at dose levels corresponding to 27%, 41%, 63% and 100% of the dose used for screen-film. The images are used in a four-alternative forced choice (4-AFC) observer perception study in order to measure threshold detectability. A statistically significant improvement in contrast detectability is measured with the digital detector at 100% and 63% of the screen-film dose. There is no statistical difference between screen-film and digital at 41% of the dose. On average, the experimental EPDR is 44%, which agrees well with the model prediction of 40%.

Equipment Design↗
PubMed1998

Effects of motion blurring in x-ray fluoroscopy.

In conventional fluoroscopy, continuous x-ray exposure blurs moving objects, while in pulsed fluoroscopy, short duration x-ray pulses acquire images without motion blur. Many perception experiments on noisy image sequences are consistent with low-pass temporal filtering by the human visual system, and this is anticipated to cause visual system "blurring" of moving objects. With moving cylinders in spatially white noise, we simulated 30 acq/s (acquisitions per second), continuous fluoroscopy having both x-ray and visual system motion blur. We also simulated pulsed fluoroscopy at 30 acq/s (pulsed-30) having visual system but not x-ray system motion blur. For both continuous and pulsed-30 acquisitions, with increasing velocity, detectability of small cylinders decreased by as much as approximately 50%, while detectability of large cylinders increased and then decreased. Detectability of pulsed-30 was only slightly higher than continuous, indicating that visual system motion blurring dominated x-ray system blurring. For the case of stationary objects, blurring greatly reduced detectability, indicating that last-image-hold of moving objects deteriorates with continuous acquisitions. With no free parameters, a human observer model with an independently measured spatio-temporal contrast sensitivity function accurately described all effects.

Contrast Sensitivity↗
PubMed1998

Detection of moving objects in pulsed-x-ray fluoroscopy.

We investigated the detectability of moving, low-contrast objects in white-noise image sequences. The computer-generated, cylindrical phantoms mimicked arteries, catheters, and guide wires in medical, x-ray fluoroscopy image sequences at 16 acquisitions/s (pulsed-16) or 32 acquisitions/s (pulsed-32). We measured detectability by using a reference-test, adaptive forced-choice method whereby reference and test presentations were alternated during an experimental session to minimize effects of subject attention and accuracy criteria. In the case of the largest cylinder (diameter 0.48 deg), the highest speed (5.86 deg/s) increased absolute detectability by approximately 42% compared with that in the stationary case. With the smallest cylinder (diameter 0.023 deg), this motion decreased detectability by approximately 51%. The dose savings of pulsed-16 was approximately 18% of that for pulsed-32, with relatively little effect of velocity or object size. In general, subjects took slightly longer to respond in the case of low-acquisition fluoroscopy. Detectability data were modeled with a nonprewhitening matched filter that included a physiological, spatiotemporal contrast sensitivity function and a suboptimal, spatiotemporal signal template with time-limited memory.

Fluoroscopy↗
PubMed1998

[Changes in serum levels of total amino acids in young children with congenital heart diseases].

OBJECTIVE: To study the implication of early surgical operation on the improvement of protein malnutrition in young children with congenital heart diseases. METHODS: Sixteen kinds of serum free amino acids were determined with an automatic analyzer for 72 cases with congenital heart diseases before and after surgical operation and 51 healthy children. RESULTS: Serum total amount of essential amino acids reduced in children with congenital heart diseases, mainly of branch-chained amino acids, especially significant in young ones. Serum amino acids restored to normal level one month after surgical operation. CONCLUSION: There existed protein malnutrition in children with congenital heart diseases, especially in young ones. Surgical operation for them in a suitable time will improve their protein nutritional status.

Adolescent↗
PubMed1997

International clinical trials of HIV vaccines: II. phase I trial of an HIV-1 synthetic peptide vaccine evaluating an accelerated immunization schedule in Yunnan, China.

A Phase 1, double-blind, placebo controlled trial was conducted in Longchuan County, China, to evaluate the safety and immunogenicity of a prototype HIV-1 synthetic peptide vaccine in a target population at risk for HIV infection, and to establish the infrastructure for future large-scale HIV vaccine efficacy trials. Subjects were randomly assigned to receive 100 microg or 500 microg of vaccine or alum placebo, and were given three injections at an accelerated 0, 1, and 2 month schedule. The vaccine was well tolerated with no significant local or systemic reactions observed in any subjects. Fifty-five percent (100 microg dose) and 64% (500 microg dose) of subjects who received the vaccine produced binding antibody to the immunogen as determined by ELISA. However, HIV-1 (MN) neutralizing antibody was detected in only 23% (3/13) of subjects with detectable HIV-1 specific binding antibody. It was concluded that this prototype HIV-1 synthetic peptide vaccine was well tolerated, safe and immunogenic, and that a 0, 1, 2 month schedule was not as effective in stimulating HIV-1 specific neutralizing antibodies compared with previous trials utilizing a 0, 1, 6 month schedule. Finally, this trial demonstrated that well-designed HIV vaccine trials can be performed at this clinical trials site in Yunnan, China, and that this site should be considered for conducting larger safety, immunogenicity and efficacy trials of candidate HIV vaccines.

AIDS Vaccines↗
PubMed1996

Pathology of the motor-sensory axonal Guillain-Barré syndrome.

The concept of a severe motor-sensory neuropathy of acute onset caused by an immune attack on the axon ("axonal" Guillain-Barré syndrome) has been advanced primarily based on electrodiagnostic and limited pathological data, but remains controversial. At autopsy some cases demonstrate unusually severe inflammatory demyelinating neuropathy. There are conflicting data about whether antecedent Campylobacter jejuni infection is associated with "axonal" Guillain-Barré syndrome. We report 4 individuals from Hebei Province, China, who died 7, 7, 18, and 60 days after onset of a syndrome diagnosed clinically as Guillain-Barré syndrome. High titers of antibodies recognizing C. jejuni, consistent with recent infection, were found in the 2 patients tested. At autopsy the 3 with early disease had ongoing wallerian-like degeneration of fibers in the ventral and dorsal roots and in the peripheral nerves, with only minimal demyelination or lymphocytic infiltration. All 3 had numerous macrophages in the periaxonal space of myelinated internodes, and rare intraaxonal macrophages as well. Examination of the patient having the syndrome for 60 days confirmed the extensive loss of large fibers in the spinal roots and nerves, and the paucity of demyelination and remyelination. These observations confirm predictions that some patients with severe motor-sensory Guillain-Barré syndrome, as defined clinically, have predominantly axonal lesions of both motor and sensory fibers, even in the early stages of the disease, and that axonal Guillain-Barré syndrome can follow C. jejuni infection. The pathology supports the possibility that such cases of motor-sensory axonal Guillain-Barré syndrome represent the most severe end of a spectrum of immune attack directed toward epitopes on the axon.

Acute Disease↗
PubMed1996

Early nodal changes in the acute motor axonal neuropathy pattern of the Guillain-Barré syndrome.

The axonal patterns of Guillain-Barré syndrome, associated in many cases with antecedent Campylobacter jejuni infection, are now recognized as frequent causes of acute flaccid paralysis in some regions of the world. This study examined ultrastructurally the PNS of seven cases of the acute motor axonal neuropathy form of Guillain-Barré syndrome. In this disorder previous studies of advanced cases have found Wallerian-like degeneration of motor fibres in the spinal roots and peripheral nerves, with little lymphocytic inflammation or demyelination. The present study was focused on identifying early changes and establishing the sequence of changes. By electron microscopy the earliest and mildest changes consisted of lengthening of the node of Ranvier with distortion of the paranodal myelin, and in some instances with breakdown of the outermost myelin terminal loops. At this stage many nodes had overlying macrophages which extended their processes through the Schwann cell basal lamina covering the node and apposed the axolemma. Macrophage processes then extended beneath the myelin terminal loops, and the whole macrophage entered the periaxonal space at the paranode. Macrophage processes dissected the axon from the adaxonal Schwann cell plasmalemma and the macrophages advanced into the internodal periaxonal space, where they typically surrounded a condensed-appearing axon. At this stage the adaxonal Schwann cell cytoplasm regularly degenerated and disappeared, so that the periaxonal space was bounded by the innermost myelin lamella, and the axolemma of many fibres could not be seen. The internodal myelin sheath and the abaxonal Schwann cell cytoplasm remained normal. This arrangement appeared to be stable for some time, but in many fibres the axon subsequently underwent Wallerian-like degeneration. By interfering with impulse conduction, these nodal and periaxonal changes may explain paralysis in some pathologically mild cases. In addition, at early stages, these changes may be reversible, thus explaining the rapid recovery of some patients who become paralysed with acute motor axonal neuropathy. These observations, taken together with previous studies, suggest that acute motor axonal neuropathy is an antibody- and complement-mediated disorder in which the relevant epitopes are present on the nodal and internodal axolemma.

Adolescent↗
PubMed1996

Pulsed fluoroscopy detectability from interspersed adaptive forced-choice measurements.

Using a new reference/test, adaptive forced-choice method, we investigated detectability of low contrast disks in simulated x-ray fluoroscopy image sequences. The method minimized effects of undesirable variables, such as changes in subject attention level by alternating conventional fluoroscopy (reference) and low acquisition rate fluoroscopy (test) presentations. To compare absolute target detectability and x-ray dose requirements of reference and test presentations, the contrast of the test presentation was set equal to that of the reference presentation, and the dose of the test presentation was adapted to give equivalent detectability of disk targets. Comparing pulsed fluoroscopy at 15 acq/s (pulsed-15) and 7.5 acq/s (pulsed-7.5) with conventional fluoroscopy at 30 acq/s (pulsed-30), dose savings were found in 22 of 24 experiments. When averaged over 3 disk sizes and 4 subjects, savings were 22% and 26% for pulsed-15 and pulsed-7.5, respectively. In most experiments, the subject was given an unlimited time to view presentations. With unlimited display times, subjects took slightly longer to respond for pulsed-15 or pulsed-7.5 than for pulsed-30. In other experiments, display times were limited. As the restricted display time increased, absolute target detectability increased while the x-ray dose for equivalent detectability was unchanged. The number of frames, N, in a repeating loop was also varied. Absolute detectability increased as N increased from 1 to 30 but changed little as more frames were added up to 150. The new experimental paradigm gives efficient, robust comparisons of image data and is applicable to a wide variety of medical image perception problems.

Adult↗
PubMed1996

Experimental Campylobacter jejuni infection in the chicken: an animal model of axonal Guillain-Barré syndrome.

OBJECTIVE: To develop and characterise an animal model of paralytic neuropathy after Campylobacter jejuni infection. Campylobacter infection precedes development of many cases of Guillain-Barré syndrome and is particularly associated with cases having prominent axonal degeneration. Understanding the pathogenesis of Guillain-Barré syndrome after C jejuni infection has been slowed by the lack of animal models. METHODS: A spontaneous paralytic neuropathy is described that developed in chickens from the farms of four patients with Guillain-Barré syndrome. The production of paralytic neuropathy in chickens experimentally fed Campylobacter jejuni isolated from one of these patients is reported. The sciatic nerves of the spontaneously paralysed chickens were examined pathologically in teased fibres, in plastic embedded sections, and by electron microscopy. Two large groups of chickens were then fed cultures of a C jejuni (Penner type O:19) isolated from one of these patients. RESULTS: The chickens with spontaneous paralysis had pathologically noninflammatory neuropathy. Pathology in the sciatic nerves ranged from no detectable changes to severe Wallerian-like degeneration. In the experimentally inoculated groups, an average of 33% of the chickens became paralysed. The median time after inoculation to paralysis was 12 days. The lesions found in the first few days of paralysis included nodal lengthening and paranodal demyelination. In those animals that survived for several days after onset of weakness, the pathology was dominated by extensive Wallerian-like degeneration. Animals that survived for weeks with no clinically apparent neuropathy had paranodal remyelination in some teased nerve fibres, reflecting earlier paranodal demyelination. CONCLUSION: Experimental inoculation with C jejuni may provide a new model for understanding some forms of Guillain-Barré syndrome.

Animals↗
PubMed1995

Guillain-Barré syndrome in northern China. The spectrum of neuropathological changes in clinically defined cases.

The pathology of the Guillain-Barré syndrome remains controversial, and autopsied cases available for study by contemporary techniques are uncommon. Large numbers of cases clinically diagnosed as Guillain-Barré syndrome occur in northern China. In this study we examined the neuropathological changes in 12 autopsied cases from Hebei Province, China. Eleven died early in the course of their disease. In all cases tissue was specially handled and fixed for electron microscopy and for immunocytochemistry. Three of these 12 cases had typical acute inflammatory demyelinating polyneuropathy (AIDP) with lymphocytic infiltration and macrophage-mediated demyelination, reproducing the pathological picture most often reported in Guillain-Barré syndrome in North America, Europe, and Australia. Six cases had predominantly axonal involvement, characterized by Wallerian-like degeneration of nerve fibres, with only minimal demyelination and with minimal inflammation in five. Three cases, even though paralysed at the time of death, had only very mild changes in the spinal roots and sciatic nerves. Within the group of six predominantly axonal cases, there were important differences both in the severity of the abnormalities and in the classes of fibres involved. Three cases had extensive Wallerian-like degeneration of sensory as well as motor fibres [acute motor-sensory axonal neuropathy (AMSAN)], while in the other three cases the fibre degeneration affected the motor nerve fibres almost exclusively. These latter cases establish a structural basis for the clinical and electrophysiological picture termed the acute motor axonal neuropathy (AMAN) pattern. In both the AMAN and the AMSAN patterns, a prominent feature was the presence of macrophages within the periaxonal space, surrounding or displacing the axon, and surrounded by an intact myelin sheath. These studies show that the early pathological changes in cases clinically diagnosed as the Guillain-Barré syndrome are diverse and not restricted to the well-known pattern of AIDP, and that the predominant pathological patterns may differ in different parts of the world. The differences in pathological findings between acute inflammatory demyelinating polyneuropathy and the axonal patterns are likely to reflect differences in the pathogenetic mechanisms. The periaxonal macrophages in the axonal patterns suggest that an important epitope may be localized to the axolemma or periaxonal space. The mild cases indicate that severe paralysis can occur early in Guillain-Barré syndrome without prominent structural changes along the nerve, suggesting that physiological block or nerve terminal changes may be implicated.

Acute Disease↗
PubMed1995

[Studies on the deltamethrin-medicated bath of domestic dogs for interrupting visceral leishmaniasis transmission].

In a previous paper, it was reported that deltamethrin-medicated bath of domestic dogs had a strong killing effect against Ph. chinensis, and could also inhibit its blood sucking ability or cause its death shortly after blood sucking. The effect could last for 30 days to 114 days, and mostly for 2 months in the local area. Based on our previous study, three villages (Yongle, Yongfeng, Anle) and a town (Chengguan) were selected from the mountainous region with high incidence of visceral leishmaniasis in Nanping County, northern Sichuan for carrying out an extensive experiment of medicated bathing of domestic dogs, where there were 13 new infected cases in the year of 1991 before the experiment. During the sandfly season in 1992, two rounds of medicated bathing of dogs were conducted, the drug concentration used was 50 ppm. From September 1992 to August 1993, the number of new infected cases was 11 in the above mentioned three villages and a town. Another two rounds of medicated bathing of dogs had been conducted during the sandfly season in 1993. The results show that there was no new infection from September 1993 to October 1994 in the three villages and a town, indicating that through two years' consecutive extensive medicated bathing of dogs in the endemic areas, canine visceral leishmaniasis transmission had been significantly interrupted. The authors consider that in the mountainous region of southern Gansu and northern Sichuan where it has been difficult to treat dogs, it might be more practical to use deltamethrin bathing of dogs for interrupting the transmission of canine visceral leishmaniasis.

Animals↗