Biomedical subjects

R Zhu

Publications and source records attributed to R Zhu.

At least 19 recordsLinked to original sources

PubMed2001

Stochastic resonance in delayed two-coupled oscillators without common perturbations.

Stochastic resonance (SR) in a two-coupled oscillator system with time delay is investigated. The system shows multistability of a desynchronized state and two synchronized states with different collective frequencies, which may be interpreted as multistable perception of ambiguous or reversible figures. To model the situations where the two oscillators exist in different environments, periodic signals and noises at their inputs are not uniformly given. SR in an individual oscillator, characterized by the output signal-to-noise ratio, is examined based on numerical simulations. We find that phase shift between the signals at inputs of different oscillators weakens SR, the oscillator with only an input signal does not show SR, and the oscillator with input noise shows SR irrespective of it having an input signal or not. The results have implications in the area of information transmission in biological systems.

Journal Article↗

PubMed2001

Determination of scopolamine, atropine and anisodamine in Flos daturae by capillary electrophoresis.

A capillary electrophoresis method was developed for the separation and determination of tropane alkaloids in Flos daturae plants. Separation was performed on a fused silica capillary(42.1 cm x 50 microm i.d.) at an applied voltage of 20 kV. Scopolamine, atropine and anisodamine were well separated in the buffer of 50 mmol/L phosphate buffer (pH 5.0) containing 20% (v/v) tetrahydrofuran (THF). Beer's law was obeyed in the range of concentration of 2.4-21.8 microg/mL for scopolamine, 4.0-36.0 microg/mL for atropine and 2.6-23.7 microg/mL for anisodamine, respectively, and the correlation coefficients were over 0.999 (n = 6). The developed method was applied for the analysis of herb samples.

Atropine↗

PubMed2001

Clinical study of scrotum scintigraphy in 49 patients with acute scrotal pain: a comparison with ultrasonography.

The significance of scrotum scintigraphy in differentiating acute testicular torsion from acute orchiepididymitis was evaluated. In this report, 49 patients with acute scrotal pain were examined with radionuclide scrotum scintigraphy and ultrasonography in parallel for comparison. Of 37 patients with decreased radioactivity in the abnormal side scrotum, 35 were diagnosed with testicular torsion surgically and the other 2 were diagnosed with indirect inguinal hernia. Only 17 among the 35 patients were diagnosed by ultrasonography as having testicular torsion. The remaining 12 patients with increased radioactivity in the abnormal side of the scrotum were all diagnosed with orchiepididymitis through conservative treatment and clinical follow-up, but only 8 of the 12 were correctly and exactly diagnosed by ultrasonography. In the process of diagnosing acute scrotal pain, radionuclide scrotum scintigraphy has obvious advantage over ultrasonography. It also has the advantage of being simple, fast and accurate but without any detrimental effect on the human body.

Adolescent↗

PubMed2001

Activation of natural killer T cells by alpha-galactosylceramide treatment prevents the onset and recurrence of autoimmune Type 1 diabetes.

Type 1 diabetes (T1D) in non-obese diabetic (NOD) mice may be favored by immune dysregulation leading to the hyporesponsiveness of regulatory T cells and activation of effector T-helper type 1 (Th1) cells. The immunoregulatory activity of natural killer T (NKT) cells is well documented, and both interleukin (IL)-4 and IL-10 secreted by NKT cells have important roles in mediating this activity. NKT cells are less frequent and display deficient IL-4 responses in both NOD mice and individuals at risk for T1D (ref. 8), and this deficiency may lead to T1D (refs. 1,6-9). Thus, given that NKT cells respond to the alpha-galactosylceramide (alpha-GalCer) glycolipid in a CD1d-restricted manner by secretion of Th2 cytokines, we reasoned that activation of NKT cells by alpha-GalCer might prevent the onset and/or recurrence of T1D. Here we show that alpha-GalCer treatment, even when initiated after the onset of insulitis, protects female NOD mice from T1D and prolongs the survival of pancreatic islets transplanted into newly diabetic NOD mice. In addition, when administered after the onset of insulitis, alpha-GalCer and IL-7 displayed synergistic effects, possibly via the ability of IL-7 to render NKT cells fully responsive to alpha-GalCer. Protection from T1D by alpha-GalCer was associated with the suppression of both T- and B-cell autoimmunity to islet beta cells and with a polarized Th2-like response in spleen and pancreas of these mice. These findings raise the possibility that alpha-GalCer treatment might be used therapeutically to prevent the onset and recurrence of human T1D.

Animals↗

PubMed2001

[Characteristics of N2O emissions from vegetal soils on Fildes peninsula, Antarctica].

The N2O fluxes from the vegetal soils were first measured on the Fildes peninsula, Antarctica, and the total N2O emission was also estimated in the summer 2 months. The daily variations of N2O fluxes appeared single-peak trend under the sunshine or rainy weather conditions but they were irregular under the snow weather conditions and inconsistent with the atmospheric temperatures. The seasonal variations of the N2O fluxes were affected by the temperature and rainfall. The conditions during the transitions between dry and wet seasons improved the N2O emission. The total N2O emissions from moss and lichen soils were 3.7152 kg and 2.5344 kg, respectively. It follows that the vegetal soils are the sources for the atmospheric N2O on the Fildes peninsula, Antarctica.

Antarctic Regions↗

PubMed2001

[Measurement of CO2 concentration in the areas with vegetation cover on the Fildes peninsula, Antarctica].

The average CO2 concentration was above 473.5 mg.m-3 in the areas covered by moss or lichen, greatly higher than the global average CO2 concentration, implying that these areas may be one of the atmospheric CO2 sources. Abnormally high CO2 concentration was relative with vegetal physiological and ecological characters. In the areas covered by moss, the daily variation of the CO2 concentrations was affected by sunshine and temperature and it was also different under the conditions of the different weathers. Sunshine was the main factors influencing the CO2 concentration. The seasonal variation of the CO2 concentration was negatively correlated with atmospheric temperature and positively with rainfall and air relative humidity. This article first presents the variations of CO2 concentration and its influential factors under the Antarctic environmental conditions, which also presents new information for the further study to the Antarctic greenhouse gases.

Air↗

PubMed2001

[Current evolution of plasma sprayed hydroxyapatite coating].

The present attempt is to briefly review the processing and properties of plasma sprayed hydroxyapatite coatings in terms of characteristics of hydroxyapatite ceramics, plasma spraying technology, titanium-ceramic interfacial cracking and component designing of hydroxyapatite coating based composite. The coating is a weak part in implant system. The main purpose of research on plasma spraying technology and component designing is to improve coating integrality and coating-matrix adhesion strength. Functionally gradient materials can provide a new route to solve the above two problems.

Biomechanical Phenomena↗

PubMed2001

[Effects of anti-idiotypic antibody NP30 on modulation of egg granuloma formation and hepatic fibrosis of schistosomiasis].

OBJECTIVE: To study the effects of the monoclonal anti-idiotypic antibody NP30 active immunization on egg granuloma formation and hepatic fibrosis in Schistosoma japonicum infection. METHODS: ICR mice were actively immunized with NP30 100 micrograms x 3 i.p. every 10 days while the mice in control group were injected with SP2/0 ascites i.p. simultaneously. After cercariae challenging, the mice were killed at the 4th, 8th, 12th, 16th, 20th and 24th week, respectively. Mouse livers were removed and stained histochemically with VG and subjected to immunohistochemical assay of collagen type I, III and fibronectin(FN). The volume of egg granulomas and the content of collagen type I, III and FN were determined quantitatively by NYD-1000 Image Analysis System. RESULTS: The volume of egg granulomas in NP30 immunized group was much smaller than that of control group from the 12th week after cercariae challenge. The cellular components of egg granulomas in NP30 immunized group were significantly different from those of the control group, exhibiting two types of atypical egg granulomas were found. VG stain revealed that the average optical density of collagen in hepatic granulomas of experimental group was lower than that of control group. Immunohistochemical assay revealed that the contents of collagen type I, III and fibronectin in egg granulomas of experimental group were lower than those of control group. CONCLUSION: NP30 vaccination may induce both cellular and humoral protective immunity to modulate egg granulomas and suppress liver fibrosis of schistosomiasis japonica.

Animals↗

PubMed2001

[Analysis of the plasma radiation induced by laser ablating Al at low pressure].

The plasma was obtained with Nd:YAG laser ablating aluminum. The energy of a pulsed laser beam was set up to 145 mJ. Ar gas was used as protecting gas, its pressure was set up to 100 Pa. The information of the plasma radiation was acquired with time-resolved technique. The time-resolved spectra including continuum radiation, absorption of continuum radiation and Al atomic spectral lines radiation were obtained. The evolutions of all these radiations were analyzed, and the relationship between them was discussed briefly. We found that the evolutions of all these radiation at the low pressure were similar to that of at the pressure of one atmosphere.

English Abstract↗

PubMed2000

Suppression of endogenous bcl-2 expression by antisense treatment exacerbates ischemic neuronal death.

Previous studies have shown that overexpression of bcl-2 in transgenic mice or by viral vectors protects the brain against cerebral ischemia. However, it is not known whether bcl-2, which is endogenously expressed in response to ischemia, exerts a protective effect. To address this question, the authors blocked the endogenous expression of bcl-2 after ischemia using antisense oligodeoxynucleotides (ODN). Antisense, sense, scrambled ODN, or vehicles were infused in the lateral ventricle of the rat for 24 hours after 30 minutes of temporary middle cerebral artery occlusion. Twenty-four hours later the brains were removed and bcl-2 protein expression was assayed by Western blot. Antisense ODN, but not sense or scrambled ODN treatment, significantly inhibited bcl-2 protein expression after ischemia. Bcl-2 protein expression was also studied 24 hours after 60 minutes of temporary middle cerebral artery occlusion in vehicle and antisense ODN-treated rats. After 60 minutes of ischemia and vehicle treatment, bcl-2 was expressed in many neurons in the ventral cortical mantle and the medial striatum. After antisense ODN treatment there were few neurons in this region expressing bcl-2, instead most neurons TUNEL labeled. Treatment with the antisense ODN, but not sense ODN, increased infarction volume as determined by cresyl violet staining 72 hours after ischemia compared with vehicle controls. These results suggested that endogenously expressed bcl-2 promoted survival in ischemic neurons and was not simply an epiphenomenon in neurons already destined to live or die.

Animals↗

PubMed2000

[Effects of stress level on the biomechanical behavior of the temporomandibular joint disc in domestic pigs].

This study aimed to examine the responses of the temporomandibular joint (TMJ) disc against compression, to clarify the property of viscoelasticity and permeability of the disc, and to provide experimental data for further analyzing the mechanism of stress dissipation within the TMJ disc. With the use of confined compression mechanics and biphasic theory, creep experiments on eight TMJ discs of four domestic pigs were performed under three stress levels(0.07 MPa, 0.13 MPa and 0.30 MPa). The results showed that at 0.07 stress level, the compressive stiffness at 2 seconds of the anterior band(AB), intermediate zone(IZ) and posterior band(PB) of the disc was 4.48 MPa, 3.93 MPa and 6.31 MPa, respectively; the coefficient K of permeability was 0.272 x 10(-12) m4/NS, 0.30 x 10(-12) m4/NS, and 0.042 x 10(-12) m4/NS. At 0.30 Mpa level, the compressive stiffness increased to 14.07 MPa, 13.68 Mpa and 14.00 MPa; the coefficient K lowered to 0.017 x 10(-12) m4/NS, 0.012 x 10(-12) m4/NS and 0.005 x 10(-12) m4/NS. In conclusion, the TMJ disc has viscoelastic and biobiphasic properties against compression. The stiffness of the disc increases with the increment of stress level but the coefficient of permeability decreases. These findings demonstrate that the modulation of stress and of permeability may be two important factors influencing stress dissipation and shock absorption behavior of the disc during compressive and impact loads.

Animals↗

PubMed1999

[A study of HGV infection in liver tissue of hepatocellular carcinoma].

OBJECTIVE: To investigate the prevalence of hepatitis G virus (HGV) in hepatocellular carcinoma (HCC). METHODS: HGV NS5 antigen was detected in paraffin-embedded HCC tissues from 53 autopsy patients by using immunohistochemical method with antiHGV NS5 monoclonal antibody. RESULTS: Among the 53 subsjects, 20(37.7%) had been detected of HGV antigen (HGAg) in HCC tissues. When serological markers were used, the HGAg detection rate was 2/8(25%) in non-B and non-C, 16/41(39%) in HBV and 2/2 in HCV infection groups, respectively. CONCLUSION: The infection of HGV is often seen in patients with HCC. HGV infection does not appear to account for an important independent risk factor for development of HCC.

Adult↗

PubMed1999

Predictors of an acute antidepressant response to fluoxetine and sertraline.

Sertraline and fluoxetine have different pharmacologic and pharmacokinetic profiles which may be of clinical relevance in the determination of response in different subtypes of depression. A randomized, double-blind, 6-week study comparing sertraline (50-100 mg/day) with fluoxetine (20-40 mg/day) in 286 outpatients with major depression, who had demonstrated comparable efficacy and tolerability for the two drugs, was analysed by subgroups of patients at baseline with melancholia, severe depression, single depressive episode, multiple depressive episodes, high anxiety, low anxiety, psychomotor retardation and psychomotor agitation. Multiple logistic regression with regressors including treatment-by-subgroup variables revealed that, within certain subgroups, the efficacy might differ substantially from that of the whole treatment group. However, the only treatment-by-subgroup interaction term that was significant was anxiety (P < 0.05). There was no evidence of interaction in single or recurrent episode subgroups, and these were not included in subsequent analyses. Subsequent two-sample statistical comparison tests of response (i.e. Hamilton Depression Scale reduction > or = 50%) rates at study endpoint between treatment groups demonstrated that patients with melancholic depression and those with symptoms of psychomotor agitation yielded a significantly greater proportion of responders with sertraline compared to fluoxetine (P < 0.05). Response rates in sertraline- and fluoxetine-treated patients, respectively, were: overall study 59%, 51%; melancholia 59%, 44%; severe depression 59%, 41%; low anxiety 71%, 55%; high anxiety 47%, 48%; psychomotor retardation, 48%, 46%; and psychomotor agitation 62%, 39%. Multiple logistic regression adjusting for possible confounding factors, that included a treatment by anxiety interaction term, also led to similar findings. In particular, the analysis showed that significant differences existed in favour of sertraline in patients with low anxiety in the melancholia and severe depression subgroups (P < 0.05), indicating that these characteristics predicted a superior response to 6 weeks of treatment with sertraline relative to fluoxetine. Sertraline also demonstrated advantages over fluoxetine on parameters such as sleep and weight disturbance in severely depressed patients, and sleep disturbance, weight, cognitive disturbance and retardation in melancholic patients.

Adult↗

PubMed1999

[Mesothelioma in rats following-intrapleural-injection of crocidolite].

In order to investigate the potential of pleural mesothelioma induced by crocidolite, author collected samples from four county areas (Dayao, Yaoan, Muding and Yanyuan) in China. A suspension of 1 ml containing 20 mg crocidolite fiber was injected into the right pleural cavity of each rat in various test groups and UICC crocidolite group, totally 40 mg. The negative control was given saline. The results showed that the incidence of mesothelioma was 56.0%-68.8% (in which the rate of induction in Yanyuan group was the highest), and the survival time of the first case of mesothelioma was 273-347 days in the test groups, the Yanyuan group had shorter latency, and the mean survival days of the rats with mesothelioma for four groups were 560, 490, 593 and 498 days respectively; the shortest mean survival time was that for Yanyuan group. The major histological type of mesothelioma induced by crocidolite was the fibrous type. The degree of differentiation in all mesotheliomas was mainly intermediate and low. The results suggested that when rats were intrapleurally inoculated with samples of crocidolite and saline, an appreciable proportion of animals developed mesothelioma except those of the saline group. Compared with other groups, the Yanyuan group had stronger potential of crocidolite-induced mesothelioma.

Animals↗

PubMed1999

[Cloning and sequencing of cDNA from G protein gene of subgroup B respiratory syncytial virus strain isolated in China].

The nucleotide sequence of the G protein gene of respiratory syncytial virus (RSV) CC169 strain isolated from China that has been identified as subgroup B with monoclonal antibodies, was determined from cDNA that had been amplified by RT-PCR and cloned into pTZ18R plasmid vector. The homology of nucleotide was 94% as compared with G protein cDNA of a RSV prototype strain (CH18537). Deduced amino acid identity of G protein was 89.4%. The amino acid changes were only in the extracellular part of the protein where there were two extensive divergent domains with a highly conserved region in between; whereas the cytoplasmic and transmembrane domains were conserved. This study demonstrates the sequence diversity of the G protein of subgroup B RSV between a Chinese isolate and the prototype strain CH18537.

Amino Acid Sequence↗

PubMed1998

Post-column derivatization for fluorescence and chemiluminescence detection in capillary electrophoresis.

Instrumental developments and applications of post-column derivatization for fluorescence and chemiluminescence detection in capillary electrophoresis (CE) are reviewed. Various systems to merge the reagent solution with the separation medium have been developed, including coaxial capillary reactors, gap reactors and free solution or end-column systems. For all reactor types the geometry of the system, as well as the method to propel the reaction mixture (by pressure or by voltage) appeared to be critical to preserve the separation efficiency. Plate numbers of over 100,000 could be realised with different reactors. The strict requirements on the rate of post-column derivatization reactions to be applied in CE limit the number of different reagents that have been used. For fluorescence detection, with laser or lamps as the excitation source, so far mainly o-phthalaldehyde and its naphthalene analogue have been used as reagent. Derivatization systems that are based on complexation reactions also showed good promise for application in CE. Detection limits could be obtained that were comparable to those obtained after pre-column derivatization. Various reagents for chemiluminescence detection (e.g. the luminol and peroxyoxalate systems) have been studied. The often complicated chemistry involved made application of these reagents in CE even more difficult. Results obtained so far, in terms of sensitivity, have not been up to expectation, with detection limits usually in the order of micromol l(-1).

Chemistry Techniques, Analytical↗

PubMed1998

A critical evaluation of the planning target volume for 3-D conformal radiotherapy of prostate cancer.

PURPOSE: To determine an adequate planning target volume (PTV) margin for three-dimensional conformal radiotherapy (3D CRT) of prostate cancer, the uncertainties in the internal positions of the prostate and seminal vesicles (SV) and in the treatment setups were measured. METHODS AND MATERIALS: Weekly computed tomography (CT) scans of the pelvis (n=51) and daily electronic portal images (n=1630) were reviewed for eight patients who received seven-field 3D CRT for prostate cancer. The CT scans were registered in three dimensions to the original planning CT scan using commercially available software to measure the center-of volume (COV) motion of the prostate and SV. The daily portal images were registered to the corresponding simulation films to measure the setup displacements. The standard deviation (SD) of the internal organ motions was added to the SD of the setups in quadrature to determine the total uncertainty. Positive directions were left, anterior, and superior. Rotations necessary to register the CT scans and portal images were minimal and not further analyzed. RESULTS: The mean motion for the COV of the prostate+/-the SD was 0+/-0.9 mm in the left-right (LR), 0.5+/-2.6 mm in the anterior-posterior (AP), and 1.5+/-3.9 mm in the superior-inferior (SI) directions. The mean motion for the COV of the SV+/-the SD was 0.3+/-1.7 mm in the LR, 0.7+/-3.8 mm in the AP, and 0.9+/-3.5 mm in the SI directions. For all patients the mean isocenter displacement+/-the SD was 0+/-3.1 mm in the LR, 1.4+/-3.0 mm in the AP, and -0.4+/-2.1 mm in the SI directions. The total uncertainty for the prostate was 3.2 mm, 4.0 mm, and 4.4 mm in the LR, AP, and SI directions, respectively. For the SV, the total uncertainty was 3.5, 4.8, and 4.1 mm in the LR, AP, and SI directions, respectively. CONCLUSIONS: PTV margins of 10 to 16 mm are required to encompass all (99%) possible positions of the prostate or SV during 3D CRT. PTV margins of 7 to 11 mm will encompass the measured uncertainties with a 95% probability. PTV margins of 5 mm may not adequately cover the intended volume.

Humans↗

PubMed1998

Postcolumn derivatization of peptides with fluorescamine in capillary electrophoresis.

Fluorescamine is used as a postcolumn derivatization reagent for fluorescence detection detection of peptides after separation by capillary electrophoresis. The problems resulting from the use of an organic solvent have been solved by introducing LiC1O4 and 5% water into the postcolumn derivatization reagent. The reaction rate and detection sensitivity of amino acids and small peptides observed with fluorescamine and OPA were compared. Fluorescamine gives much higher sensitivity than o-phthaldialdehyde (OPA) for small peptides, with detection limits for the selected peptides and amino acids below 0.1 mumol 1-1. Under optimized experimental conditions, the method has a good reproducibility and separation efficiency for peptides. The method was applied for the analysis of the protein tryptic digests. Only submicromolar concentrations of proteins were required.

Amino Acids↗