PubMed Health⌕ Search

Biomedical subjects

Y K Zhang

Publications and source records attributed to Y K Zhang.

At least 19 recordsLinked to original sources
PubMed2001

Structural alterations of sugar chains in urine fibronectin from bladder cancer patients and its enzymatic mechanism.

PURPOSE: To study the structural alterations of asparagine-linked sugar chains (N-glycans) on urine fibronectin (Fn) from bladder cancer (BCa) patients and its enzymatic mechanism. METHODS: Eight pairs of urine samples from eight BCa patients pre-operation and 3 months post-operation (which proved to be normal) were collected, and the Fn in the urine samples was purified with an anti-Fn antibody affinity column. Different lectins labeled with horseradish peroxidase (HRP) were used as probes to bind the glycans of purified Fn immobilized on membrane. Enhanced chemiluminescence (ECL) reagent was adopted to estimate the activity of the bound HRP as a measure of the binding affinity of the Fn glycans to lectins, and expressed as luminescent light units (LLU). The enzymatic mechanism of the structural alteration of N-glycans in BCa Fn was studied by determination of GnT activities using the HPLC method and fluorescent-labeled substrate. RESULTS: The mean LLU of BCa Fn was only 18.1% of the normal samples when Con A-HRP were used as probes, while the mean LLU of the BCa group was 3.34 times and 3.26 times higher than normal for the DSA-HRP and WGA-HRP probes, respectively. The individual data of the patients did not overlap between the BCa sample and normal counterparts, indicating that the positive rates were 100%, regardless of which lectin-HRP was used. These results reveal that the antennary number and bisecting GlcNAc structure are increased in the N-glycans of urine Fn from BCa assessed according to the binding specificity of ConA, DSA, and WGA. In addition, the binding affinities of urine Fn with DSA and WGA were correlated to pathological stage, and the affinity of Fn with WGA was also correlated with pathological grade. The results of GnT determination showed that GnT-III, IV, and V in BCa tissues increased by 34.0, 18.1, and 1.6 times, respectively, in normal bladder tissues which were at least 5 cm away from the BCa of the same bladder. These findings were compatible with the structural changes of N-glycans in BCa Fn, since GnT-III and GnT-IV/V are responsible for the synthesis of bisecting GlcNAc and the increase of antennary number in N-glycans, respectively. CONCLUSIONS: (1) The highest elevation of GnT-III and the close relationship between the WGA binding of BCa Fn with the pathological stage and grade of BCa indicate that the increase of bisecting GlcNAc in N-linked glycans contributes more to the malignant behavior of BCa than the increase of GnT-IV, GnT-V, and the antennary number. (2) The correlation of altered activities of bladder GnTs with the abnormal structures of urine Fn in BCa patients indicates that the urine Fn is synthesized in the bladder. (3) The lectin-HRP assay for analyzing the structure of N-glycans in urine Fn may be used as a simple and accurate diagnosis method for BCa in the future.

Adult↗
PubMed2001

Comparison of the radical trapping ability of PBN, S-PPBN and NXY-059.

The nitrones alpha-phenyl-N-tert-butyl nitrone (PBN), sodium 2-sulfophenyl-N-tert-butyl nitrone (S-PBN) and disodium 2,4-disulfophenyl-N-tert-butyl nitrone (NXY-059) are neuroprotective in a variety of rodent models. The objective of the current studies was to compare the ability of PBN, S-PBN, and NXY-059 to form radical adducts and to prevent salicylate oxidation in an aqueous system. For the electron spin resonance (ESR) studies, hydroxyl radicals were generated with ultraviolet (UV) light and hydrogen peroxide. Secondary radicals were then produced by the addition of methanol, ethanol, isopropanol, dimethylsulfoxide, tetrahydrofuran or 1,4-dioxane. In addition, competition spin trapping studies were performed using PBN-alpha-(13) C and either S-PBN or NXY-059. In the salicylate studies, PBN, S-PBN and NXY-059 were compared to a variety of other antioxidants and reference compounds (cysteine, glutathione, ascorbate, uric acid, Tempo, Trolox, and Tirilizad) for their ability to prevent 2,3- and 2,5-dihydroxybenzoic acid formation induced by hydroxyl radical generating systems. All 3 nitrones trapped carbon- and oxygen-centered radicals to produce ESR-detectable radical adducts. Each nitrone also prevented salicylate oxidation, with PBN being the most effective. The ability of these 3 nitrones to prevent salicylate oxidation resembled that of most of the other compounds tested.

Antioxidants↗
PubMed2001

[A new method for predicting retention time of solutes under linear gradient elution conditions in RP-HPLC].

A new method for predicting the retention time of solutes under linear gradient elution has been established. In this method, the migration distance of solutes in column and the mobile phase gradient were modified simultaneously according to the distribution of mobile phase in column. The prediction results of retention time of both weakly and strongly retentive solutes were accurate in different instrumental systems using this method. In order to test and verify this method, the retention time of fifteen amino acids and eight homologous compounds of benzene were predicted. The predicted results were compared with those predicted by the method in common use. The relative average errors between predicted and experimental values were 3.70% and 4.90% for the weakly retentive solutes, far smaller than those obtained by the reference method (23.61% and 31.16%). For the strongly retentive solutes, the relative average errors were 0.21% and 6.01% respectively, slightly smaller than those obtained by the reference method (0.81% and 6.69%). It is seen that this new method has many advantages.

Amino Acids↗
PubMed2001

[Advances in chromatography and related techniques in China--status report in 1998-1999].

This report covers developments in chromatography and related techniques in China during the period of 1998-1999. The papers published in 23 domestic and a few foreign periodicals which are closely related to chromatography, and presented at 1999 Beijing Conference and Exhibition on Instrumental Analysis and the 12th National Symposium of Chromatography are reviewed. Specific topic areas covered include gas chromatography (GC), high performance liquid chromatography (HPLC), capillary electrophoresis (CE) and capillary electrochromatography (CEC), solid phase extraction (SPE) and solid phase microextraction (SPME).

Animals↗
PubMed2000

[Advances in nonaqueous capillary electrophoresis].

Advances in nonaqueous capillary electrophoresis are reviewed with 71 references in this paper. Capillary electrophoresis is generally performed in aqueous buffer. In fact, it can provide some advantages to use organic solvent as a separation medium instead of water. The choice of organic solvent and electrolyte, the detection mode and solute-additive interactions are summarized. Furthermore, the separation of inorganic ions, neural compounds, organic acids, pharmaceuticals, metabolites and chiral substance is also described.

Electrophoresis, Capillary↗
PubMed1999

Changes and implications of blood flow velocity of the vertebral artery during rotation and extension of the head.

OBJECTIVE: To study the effects of extension and extension-rotation of the head on the blood flow velocity of the vertebral artery experimentally and clinically. DESIGN: Randomized experimental clinical study. SETTING: Institute of Clinical Anatomy and Biomechanics and the Department of Ultrasound, NanFang Hospital of the First Military Medical University, Guangzhou, China. SUBJECTS: The fresh spines from T1-2 to the occipital bone were obtained from persons who died of acute brain death (n = 10). For the transcranial Doppler measurement, 27 asymptomatic subjects with routine physical examination results and 23 students from the above-mentioned university took part in the test. INTERVENTIONS: The instillation experiment in the cadavers was made. Clinical measurements of blood flow velocity in the vertebral artery in the subjects and students were taken and recorded. MAIN OUTCOME MEASURES: Changes in the drop of the vertebral artery were measured by the instillation test in the experimental sample. The blood flow velocity was measured with transcranial Doppler sonography during extension and extension-rotation of the head. RESULTS: During one-sided rotation of the head with extension of the head, measurements in the contralateral vertebral artery and the bilateral vertebral arteries were both reduced in the instillation experiment. The blood flow velocity in the bilateral vertebral arteries decreased during extension and extension-rotation of the head in the subjects and the students. The pulsatility index in the right vertebral arteries increased more than that in the left in extreme extension and that in the bilateral vertebral arteries in neutral position. CONCLUSIONS: Extreme rotation and extension are dangerous to patients who have abnormal vertebral arteries when extreme rotatory and extension manipulations are applied. Doctors should be very careful when rotating the patient's head to the right side.

Adult↗
PubMed1998

Antineutrophil cytoplasmic autoantibodies (ANCA) and their target antigens in Chinese patients with lupus nephritis.

BACKGROUND: ANCA have been found in patients with systemic lupus erythematosus (SLE); however, the prevalence of ANCA and their target antigens is still not certain. This study is to investigate the prevalence of ANCA and their target antigens in Chinese patients with lupus nephritis. METHODS: Ninety-five serum samples were collected from 95 renal-biopsy-proven lupus nephritis patients. Indirect immunofluorescence using ethanol-fixed leukocytes as substrate and ELISA using six highly purified known ANCA antigens as solid-phase ligands were performed. The specific ANCA antigens included proteinase 3, myeloperoxidase, bactericidal/permeability-increasing protein, human leukocyte elastase, cathepsin G, and lactoferrin. The prevalence of ANCA in patients with (n=65) and without (n=30) active renal pathological lesions was also compared to reveal whether ANCA correlates with disease activity. RESULTS: (i) None of the sera recognized proteinase 3, myeloperoxidase, and human leukocyte elastase, and only one serum recognized bactericidal/permeability-increasing protein. The striking finding was that 59/95 (62.1%) sera recognized cathepsin G and the titres of some sera reached 1/3200. Eight of 95 sera (8.4%) recognized lactoferrin. (ii) The percentage of anti-cathepsin G antibody positive samples in patients with active renal lesions was significantly higher than in patients without active lesions (73.4 vs 36.7%, P<0.0001), whereas, anti-lactoferrin antibodies had no correlation with active renal lesions. (iii) By indirect immunofluorescence, only 22% of the 95 sera were ANCA positive. CONCLUSIONS: Our results suggest that the majority of lupus nephritis patients have ANCA and that the major target antigens is cathepsin G. Anti-cathepsin G antibodies seem to be correlated with renal disease activity.

Adolescent↗
PubMed1997

Hypoxia, but not reoxygenation, induces interleukin 6 gene expression through NF-kappa B activation.

Interleukin (IL) 6 is one of major mediators of inflammation, and IL-6 gene activation during hypoxia/reoxygenation has been implicated in the pathogenesis of ischemia/reperfusion injury. However, molecular events involved in IL-6 gene expression during hypoxia/reoxygenation remain to be identified. We have previously shown that NF-kappa B plays an essential and indispensable role in the transcriptional activation of the IL-6 gene induced by various stimuli, including IL-1 and tumor necrosis factor-alpha. We show here that hypoxia, but not reoxygenation, induces the activation of NF-kappa B through the degradation of a major inhibitor of NF-kappa B, I kappa B alpha. This hypoxia-induced NF-kappa B activation resulted in the kappa B-dependent transcriptional activation of the IL-6 gene. Interestingly, the time course of hypoxia-induced NF-kappa B activation was rather slow as compared with those of NF-kappa B activation induced by other stimuli, such as IL-1: a significant NF-kappa B activation was not observed before 1 hr of hypoxia treatment and persisted for up to 7 hr of hypoxia treatment. However, hypoxia-induced NF-kappa B activation was not inhibited by cycloheximide, which indicates that hypoxia directly triggers NF-kappa B activation. Furthermore, while hypoxia is unlikely to generate reactive oxygen intermediates, pretreatment of cells with antioxidants such as N-acetyl cysteine and alpha-tocopherol inhibited NF-kappa B activation induced by hypoxia. Thus, we discuss possible implications of these results for a postulated role of reactive oxygen intermediates in NF-kappa B activation.

Animals↗
PubMed1997

Changes in N-acetylglucosaminyltransferase III, IV and V in renal cell carcinoma.

The activities of N-acetylglucosaminyltransferase (GnT) III, IV and V were determined in 10 cases of renal cell carcinoma (RCC) and compared with the normal kidney cortex (NKC) regions of the same kidney resected from RCC patients. It was found that the GnT III and GnT IV activities decreased consistently in all samples of RCC, while GnT V activity increased, decreased or did not change in different samples. The mean levels of GnT III and GnT IV activities in RCC were found to be very significantly lower than those of NKC on statistical analysis, but the mean value of GnT V activity was almost identical in RCC and NKC. The decrease in GnT activities in RCC were compatible with the decrease in bisecting N-acetylglucosamine (GlcNAc) and antennary number of complex-type N-glycans in gamma-glutamyltranspeptidase (gamma-GT) partially purified from RCCs as studied with concanavalin A (ConA) affinity column chromatography, which showed a decrease of unbound fraction and increase of bound fractions.

Adult↗
PubMed1997

Spatiotemporal characteristics of central otolith neurons.

PURPOSE: To review the spatiotemporal behaviours of central otolith neurons in decerebrate animals. DATA SOURCES: Laboratory of Neurophysiology, Department of Physiology, Faculty of Medicine, The University of Hong Kong. DATA EXTRACTION: Results of key research findings from 1992 to 1997. RESULTS: With constant velocity colckwise (CW) and counterclockwise (CCW) off-vertical axis rotations as stimuli to the otolith organs, neurons in the vestibular nuclei and medullary reticular formation showed characteristic spatiotemporal behavious. One-dimensional neurons showed symmetric and stable bidirectional response sensitivities (delta) to change in velocity while two-dimensional neurons showed asymmetric and variable delta to velocity. This CW-CCW asymmetry to bidirectional rotations may provide directional coding in the modulation of neural signals. Vestibular nuclear neurons also displayed distinct spontaneous discharge patterns at the stationary and earth-horizontal position, indicating that one- and two-dimensional neurons belong to physiologically distinct etities. These spatiotemporal behavious of the vestibular nuclear neurons were also shown to be precisely controlled by imputs from the vestibulocerebellum and/or bilateral otoliths. In both the vestibular nucleus and the reticular formation, the best response orientations of one-dimensional neurons and the orientations of the maximum response vector of two-dimensional neurons were found to point in all directions close to the horizontal plane, indicating that all head orientations on this plane are encoded across an ensemble of neurons. CONCLUSION: Otolith-evoked behaviours of the one-dimensional and two-dimensional neurons constitute an important element for the recognition of the direction and orientation of head motion in space.

Animals↗
PubMed1996

Computer-assisted peak recognition for polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) in environmental samples.

A software has been developed for the peak recognition of 136 polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) after high resolution gas chromatography coupled with mass spectrometry (HRGC/HRMS). Based on the retention times of (13)C labelled 2,3,7,8-substituted PCDD/F internal standards, the retention times of all PCDD and PCDF can be calibrated automatically and accurately. Therefore, it is very convenient to identify the peaks by comparing the retention of samples and the calibrated retention times of their chromatograms. Hence, this approach is very significant because it is impossible to obtain always a standard chromatogram and PCDD/F analysis are very expensive and time consuming. The calibration results can be transferred to Excel for calculation. The approach is a first step to store costly and environmentally relevant data for future application.

Journal Article↗
PubMed1995

Pharmacological action of a new spin trapping compound, 2-phenyl DMPO, in the adriamycin-induced cardiotoxicity.

Adriamycin (ADR)-induced cardiotoxicity was adopted in this investigation as a reliable model of radical-dependent myocardial pathology allowing both quantitative studies of drug activity in the isolated organ and in vivo comparison of the cardio-protection vs. general toxicity. Since commercially available lipophilic spin trapping compounds were shown to develop significant protective activity, in this investigation a newly synthesized spin trap (2-phenyl-DMPO) was studied. In Langendorff rat heart, 200 microM ADR induced a significant impairment of contractile performance, while 2-phenyl-DMPO was not cardiotoxic up to the 5 mM concentration. By this dose, 2-phenyl-DMPO induced a significant protection against the ADR-induced contractile impairment. In in vivo experiments, ADR (9 mg/kg i.v.) produced a significant impairment of ECG, coronary flow and contractility. The continuous administration of 2-phenyl-DMPO i.p. by osmotic pump delivering 0.3 mumol/hr was unable to protect the animals against the cardiotoxic signs. Seven days after ADR administration, severe general toxicity (arrest of body weight increase) and myelotoxicity were also observed. 2-phenyl-DMPO was unable to protect the animals from these toxic signs. The present results confirm that lipophilic spin traps can be a new class of antiradical drugs, as confirmed by the experiments performed in the isolated heart with the 2-phenyl-DMPO; however, this last compound is probably metabolized in vivo to inactivate derivatives.

Analysis of Variance↗
PubMed1994

[Changes in the extracellular matrix in human mesangial proliferative glomerulonephritis].

A quantitative analysis of the components of glomerular extracellular matrix (ECM) was performed with the immunoperoxidase method (ABC method) and the computer imaging analysis system. The results demonstrate that with the development of mesangial proliferative glomerulonephritis (MsPGN), normal components of glomerular ECM (type IV collagen, laminin, fibronectin) increased markedly. In addition, interstitial collagen (type III collagen) appeared in the expanded mesangial matrix of moderate MsPGN and increased in severe MsPGN, suggesting that MsPGN is linked to the accumulation of ECM, not only the normal components, but also the interstitial collagen.

Collagen↗
PubMed1993

MRI study of the inhibitory effect of new spin traps on in vivo CCl4-induced hepatotoxicity in rats.

Acute CCl4 hepatotoxicity is thought to occur as a result of free radicals generated from the metabolism of CCl4 in the liver. With the use of MRI it is possible to detect in vivo a CCl4-induced localized edematous region surrounding the major branch of the hepatic portal vein in the right lobe. Inhibition of the CCl4-induced response has been obtained by pretreatment with the spin trap, PBN, 30 min prior to CCl4 exposure. The inhibitory effect of two new spin traps, M3PO or methyl-DMPO, and PhM2PO or phenyl-DMPO, on in vivo CCl4-induced acute hepatotoxicity was investigated. Both PhM2PO and M3PO were found to inhibit the CCl4-induced response at lower concentrations (0.35 M/kg body weight) than PBN (0.70 M/kg body weight). However, both M3PO and PhM2PO were also found to induce an edematous response at the same concentrations used for the PBN studies (0.70 M/kg body weight). PhM2PO, at a concentration of 0.35 M/kg body weight, was 93% as efficient as PBN, at a concentration of 0.70 M/kg body weight; whereas M3PO, at a concentration of 0.35 M/kg, was 89% as efficient as PBN at 0.70 M/kg body weight. Electron micrographs were obtained from small liver sections taken in proximity to the major branch of the hepatic portal veins of all treatment groups. The electron microscopy investigations support the MRI findings.

Animals↗
PubMed1993

[The renal involvement of primary vasculitis: clinical and pathological analysis of 5 cases].

Primary vasculitis, include microscopic polyarteritis (MPA) and Wegener's granulomatosis (WG), is one of the causes of Glomerulonephritis and renal failure. Recently antineutrophil cytoplasmic autoantibodies (ANCA) is considered to be a very important tool for the diagnosis of MPA and WG. The management of ANCA was performed in 42 patients with variant primary glomerulonephritis with crescents formation or sclerotic glomerulonephritis, 5 of them show positive, appeared as a pattern of P-ANCA. Most of the patients were old male, with fever, malaise, weight loss, anemia, muscle and joint pain, some of them have chronic cough, even hemoptysis, opacities in middle-lower fields of both lungs, which didn't response to antibiotics therapy. This is the first report about renal involvement of primary vasculitis from China. Our result suggest that primary vasculitis is not a rare course of renal failure in China.

Adolescent↗
PubMed1992

[Thin membrane nephropathy (TMN). Analysis of 8 cases].

This present study first reported 8 cases of Thin membrane nephropathy (TMN) in China. Most patients had persistent microscopic hematuria, who could be accompanied with mild proteinuria or macroscopic hematuria. The contrast microscopy showed glomerular hematuria in the majority of the cases. Some patients (25%, 2 cases) had familial hematuric histories, suggesting this disease may be associated with heredity. All the patients had normal renal function at following-up period (average 2.9 years), this result showed this disease was benign glomerular disease. LM showed pathological change is mild, IF was negative, diffuse thin GBM was outstanding change by EM. The thickness of TMN was 265 +/- 39 nm, the thickness of IgA GN and normal control were separately 383 +/- 32 nm and 398 +/- 34 nm, the thickness of TMN was significantly thinner than IgA GN and normal control (P less than 0.01). This study showed ultrastructural observation of glomeruli by EM was necessary to diagnose this disease.

Basement Membrane↗